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Sample records for adaptive sliding observer

  1. Robust observer-based adaptive fuzzy sliding mode controller

    NASA Astrophysics Data System (ADS)

    Oveisi, Atta; Nestorović, Tamara

    2016-08-01

    In this paper, a new observer-based adaptive fuzzy integral sliding mode controller is proposed based on the Lyapunov stability theorem. The plant is subjected to a square-integrable disturbance and is assumed to have mismatch uncertainties both in state- and input-matrices. Based on the classical sliding mode controller, the equivalent control effort is obtained to satisfy the sufficient requirement of sliding mode controller and then the control law is modified to guarantee the reachability of the system trajectory to the sliding manifold. In order to relax the norm-bounded constrains on the control law and solve the chattering problem of sliding mode controller, a fuzzy logic inference mechanism is combined with the controller. An adaptive law is then introduced to tune the parameters of the fuzzy system on-line. Finally, for evaluating the controller and the robust performance of the closed-loop system, the proposed regulator is implemented on a real-time mechanical vibrating system.

  2. Adaptive sliding mode controller based on super-twist observer for tethered satellite system

    NASA Astrophysics Data System (ADS)

    Keshtkar, Sajjad; Poznyak, Alexander

    2016-09-01

    In this work, the sliding mode control based on the super-twist observer is presented. The parameters of the controller as well as the observer are admitted to be time-varying and depending on available current measurements. In view of that, the considered controller is referred to as an adaptive one. It is shown that the deviations of the generated state estimates from real state values together with a distance of the closed-loop system trajectories to a desired sliding surface reach a μ-zone around the origin in finite time. The application of the suggested controller is illustrated for the orientation of a tethered satellite system in a required position.

  3. Interpolating sliding mode observer for a ball and beam system

    NASA Astrophysics Data System (ADS)

    Luai Hammadih, Mohammad; Hosani, Khalifa Al; Boiko, Igor

    2016-09-01

    A principle of interpolating sliding mode observer is introduced in this paper. The observer incorporates multiple linear observers through interpolation of multiple estimates, which is treated as a type of adaptation. The principle is then applied to the ball and beam system for observation of the slope of the beam from the measurement of the ball position. The linearised model of the ball and beam system using multiple linearisation points is developed. The observer dynamics implemented in Matlab/Simulink Real Time Workshop environment. Experiments conducted on the ball and beam experimental setup demonstrate excellent performance of the designed novel interpolating (adaptive) observer.

  4. Sliding mode control of wind-induced vibrations using fuzzy sliding surface and gain adaptation

    NASA Astrophysics Data System (ADS)

    Thenozhi, Suresh; Yu, Wen

    2016-04-01

    Although fuzzy/adaptive sliding mode control can reduce the chattering problem in structural vibration control applications, they require the equivalent control and the upper bounds of the system uncertainties. In this paper, we used fuzzy logic to approximate the standard sliding surface and designed a dead-zone adaptive law for tuning the switching gain of the sliding mode control. The stability of the proposed controller is established using Lyapunov stability theory. A six-storey building prototype equipped with an active mass damper has been used to demonstrate the effectiveness of the proposed controller towards the wind-induced vibrations.

  5. Adaptive sliding mode control for a class of chaotic systems

    SciTech Connect

    Farid, R.; Ibrahim, A.; Zalam, B.

    2015-03-30

    Chaos control here means to design a controller that is able to mitigating or eliminating the chaos behavior of nonlinear systems that experiencing such phenomenon. In this paper, an Adaptive Sliding Mode Controller (ASMC) is presented based on Lyapunov stability theory. The well known Chua's circuit is chosen to be our case study in this paper. The study shows the effectiveness of the proposed adaptive sliding mode controller.

  6. Adaptive robust controller based on integral sliding mode concept

    NASA Astrophysics Data System (ADS)

    Taleb, M.; Plestan, F.

    2016-09-01

    This paper proposes, for a class of uncertain nonlinear systems, an adaptive controller based on adaptive second-order sliding mode control and integral sliding mode control concepts. The adaptation strategy solves the problem of gain tuning and has the advantage of chattering reduction. Moreover, limited information about perturbation and uncertainties has to be known. The control is composed of two parts: an adaptive one whose objective is to reject the perturbation and system uncertainties, whereas the second one is chosen such as the nominal part of the system is stabilised in zero. To illustrate the effectiveness of the proposed approach, an application on an academic example is shown with simulation results.

  7. Sliding mode observers for automotive alternator

    NASA Astrophysics Data System (ADS)

    Chen, De-Shiou

    Estimator development for synchronous rectification of the automotive alternator is a desirable approach for estimating alternator's back electromotive forces (EMFs) without a direct mechanical sensor of the rotor position. Recent theoretical studies show that estimation of the back EMF may be observed based on system's phase current model by sensing electrical variables (AC phase currents and DC bus voltage) of the synchronous rectifier. Observer design of the back EMF estimation has been developed for constant engine speed. In this work, we are interested in nonlinear observer design of the back EMF estimation for the real case of variable engine speed. Initial back EMF estimate can be obtained from a first-order sliding mode observer (SMO) based on the phase current model. A fourth-order nonlinear asymptotic observer (NAO), complemented by the dynamics of the back EMF with time-varying frequency and amplitude, is then incorporated into the observer design for chattering reduction. Since the cost of required phase current sensors may be prohibitive, the most applicable approach in real implementation by measuring DC current of the synchronous rectifier is carried out in the dissertation. It is shown that the DC link current consists of sequential "windows" with partial information of the phase currents, hence, the cascaded NAO is responsible not only for the purpose of chattering reduction but also for necessarily accomplishing the process of estimation. Stability analyses of the proposed estimators are considered for most linear and time-varying cases. The stability of the NAO without speed information is substantiated by both numerical and experimental results. Prospective estimation algorithms for the case of battery current measurements are investigated. Theoretical study indicates that the convergence of the proposed LAO may be provided by high gain inputs. Since the order of the LAO/NAO for the battery current case is one order higher than that of the link

  8. Adaptive sliding mode control - convergence and gain boundedness revisited

    NASA Astrophysics Data System (ADS)

    Zhu, Jiang; Khayati, Karim

    2016-04-01

    This paper reviews the main adaptive sliding mode controller (ASMC) designs for nonlinear systems with finite uncertainties of unknown bounds. Different statements of convergence referring to uniformly ultimate boundedness (UUB), asymptotic convergence (AC) and finite-time convergence (FTC) for ASMC shown in recent papers are analysed. Weaknesses and incomplete proofs apropos FTC are pointed out. Thereafter, a new approach is proposed to successfully demonstrate FTC of the so-called sliding variable. We identify a compensating phase and a reaching phase during the ASMC process. A new explicit form for estimating the upper-bound reaching time is provided for any bounded perturbation. An amended form of the real ASMC is recalled showing improved accuracy and chattering reduction. Finally, numerical and experimental applications are performed to convey the discussed results.

  9. Adaptive backstepping slide mode control of pneumatic position servo system

    NASA Astrophysics Data System (ADS)

    Ren, Haipeng; Fan, Juntao

    2016-06-01

    With the price decreasing of the pneumatic proportional valve and the high performance micro controller, the simple structure and high tracking performance pneumatic servo system demonstrates more application potential in many fields. However, most existing control methods with high tracking performance need to know the model information and to use pressure sensor. This limits the application of the pneumatic servo system. An adaptive backstepping slide mode control method is proposed for pneumatic position servo system. The proposed method designs adaptive slide mode controller using backstepping design technique. The controller parameter adaptive law is derived from Lyapunov analysis to guarantee the stability of the system. A theorem is testified to show that the state of closed-loop system is uniformly bounded, and the closed-loop system is stable. The advantages of the proposed method include that system dynamic model parameters are not required for the controller design, uncertain parameters bounds are not need, and the bulk and expensive pressure sensor is not needed as well. Experimental results show that the designed controller can achieve better tracking performance, as compared with some existing methods.

  10. A novel adaptive sliding mode control with application to MEMS gyroscope.

    PubMed

    Fei, Juntao; Batur, Celal

    2009-01-01

    This paper presents a new adaptive sliding mode controller for MEMS gyroscope; an adaptive tracking controller with a proportional and integral sliding surface is proposed. The adaptive sliding mode control algorithm can estimate the angular velocity and the damping and stiffness coefficients in real time. A proportional and integral sliding surface, instead of a conventional sliding surface is adopted. An adaptive sliding mode controller that incorporates both matched and unmatched uncertainties and disturbances is derived and the stability of the closed-loop system is established. The numerical simulation is presented to verify the effectiveness of the proposed control scheme. It is shown that the proposed adaptive sliding mode control scheme offers several advantages such as the consistent estimation of gyroscope parameters including angular velocity and large robustness to parameter variations and external disturbances.

  11. Adaptive second-order sliding mode control with uncertainty compensation

    NASA Astrophysics Data System (ADS)

    Bartolini, G.; Levant, A.; Pisano, A.; Usai, E.

    2016-09-01

    This paper endows the second-order sliding mode control (2-SMC) approach with additional capabilities of learning and control adaptation. We present a 2-SMC scheme that estimates and compensates for the uncertainties affecting the system dynamics. It also adjusts the discontinuous control effort online, so that it can be reduced to arbitrarily small values. The proposed scheme is particularly useful when the available information regarding the uncertainties is conservative, and the classical `fixed-gain' SMC would inevitably lead to largely oversized discontinuous control effort. Benefits from the viewpoint of chattering reduction are obtained, as confirmed by computer simulations.

  12. Darkfield adapter for whole slide imaging: adapting a darkfield internal reflection illumination system to extend WSI applications.

    PubMed

    Kawano, Yoshihiro; Higgins, Christopher; Yamamoto, Yasuhito; Nyhus, Julie; Bernard, Amy; Dong, Hong-Wei; Karten, Harvey J; Schilling, Tobias

    2013-01-01

    We present a new method for whole slide darkfield imaging. Whole Slide Imaging (WSI), also sometimes called virtual slide or virtual microscopy technology, produces images that simultaneously provide high resolution and a wide field of observation that can encompass the entire section, extending far beyond any single field of view. For example, a brain slice can be imaged so that both overall morphology and individual neuronal detail can be seen. We extended the capabilities of traditional whole slide systems and developed a prototype system for darkfield internal reflection illumination (DIRI). Our darkfield system uses an ultra-thin light-emitting diode (LED) light source to illuminate slide specimens from the edge of the slide. We used a new type of side illumination, a variation on the internal reflection method, to illuminate the specimen and create a darkfield image. This system has four main advantages over traditional darkfield: (1) no oil condenser is required for high resolution imaging (2) there is less scatter from dust and dirt on the slide specimen (3) there is less halo, providing a more natural darkfield contrast image, and (4) the motorized system produces darkfield, brightfield and fluorescence images. The WSI method sometimes allows us to image using fewer stains. For instance, diaminobenzidine (DAB) and fluorescent staining are helpful tools for observing protein localization and volume in tissues. However, these methods usually require counter-staining in order to visualize tissue structure, limiting the accuracy of localization of labeled cells within the complex multiple regions of typical neurohistological preparations. Darkfield imaging works on the basis of light scattering from refractive index mismatches in the sample. It is a label-free method of producing contrast in a sample. We propose that adapting darkfield imaging to WSI is very useful, particularly when researchers require additional structural information without the use of

  13. Adaptive suboptimal second-order sliding mode control for microgrids

    NASA Astrophysics Data System (ADS)

    Incremona, Gian Paolo; Cucuzzella, Michele; Ferrara, Antonella

    2016-09-01

    This paper deals with the design of adaptive suboptimal second-order sliding mode (ASSOSM) control laws for grid-connected microgrids. Due to the presence of the inverter, of unpredicted load changes, of switching among different renewable energy sources, and of electrical parameters variations, the microgrid model is usually affected by uncertain terms which are bounded, but with unknown upper bounds. To theoretically frame the control problem, the class of second-order systems in Brunovsky canonical form, characterised by the presence of matched uncertain terms with unknown bounds, is first considered. Four adaptive strategies are designed, analysed and compared to select the most effective ones to be applied to the microgrid case study. In the first two strategies, the control amplitude is continuously adjusted, so as to arrive at dominating the effect of the uncertainty on the controlled system. When a suitable control amplitude is attained, the origin of the state space of the auxiliary system becomes attractive. In the other two strategies, a suitable blend between two components, one mainly working during the reaching phase, the other being the predominant one in a vicinity of the sliding manifold, is generated, so as to reduce the control amplitude in steady state. The microgrid system in a grid-connected operation mode, controlled via the selected ASSOSM control strategies, exhibits appreciable stability properties, as proved theoretically and shown in simulation.

  14. Adaptive terminal sliding-mode control strategy for DC-DC buck converters.

    PubMed

    Komurcugil, Hasan

    2012-11-01

    This paper presents an adaptive terminal sliding mode control (ATSMC) strategy for DC-DC buck converters. The idea behind this strategy is to use the terminal sliding mode control (TSMC) approach to assure finite time convergence of the output voltage error to the equilibrium point and integrate an adaptive law to the TSMC strategy so as to achieve a dynamic sliding line during the load variations. In addition, the influence of the controller parameters on the performance of closed-loop system is investigated. It is observed that the start up response of the output voltage becomes faster with increasing value of the fractional power used in the sliding function. On the other hand, the transient response of the output voltage, caused by the step change in the load, becomes faster with decreasing the value of the fractional power. Therefore, the value of fractional power is to be chosen to make a compromise between start up and transient responses of the converter. Performance of the proposed ATSMC strategy has been tested through computer simulations and experiments. The simulation results of the proposed ATSMC strategy are compared with the conventional SMC and TSMC strategies. It is shown that the ATSMC exhibits a considerable improvement in terms of a faster output voltage response during load changes.

  15. Adaptive fuzzy sliding mode control scheme for uncertain systems

    NASA Astrophysics Data System (ADS)

    Noroozi, Navid; Roopaei, Mehdi; Jahromi, M. Zolghadri

    2009-11-01

    Most physical systems inherently contain nonlinearities which are commonly unknown to the system designer. Therefore, in modeling and analysis of such dynamic systems, one needs to handle unknown nonlinearities and/or uncertain parameters. This paper proposes a new adaptive tracking fuzzy sliding mode controller for a class of nonlinear systems in the presence of uncertainties and external disturbances. The main contribution of the proposed method is that the structure of the controlled system is partially unknown and does not require the bounds of uncertainty and disturbance of the system to be known; meanwhile, the chattering phenomenon that frequently appears in the conventional variable structure systems is also eliminated without deteriorating the system robustness. The performance of the proposed approach is evaluated for two well-known benchmark problems. The simulation results illustrate the effectiveness of our proposed controller.

  16. Adaptive Actor-Critic Design-Based Integral Sliding-Mode Control for Partially Unknown Nonlinear Systems With Input Disturbances.

    PubMed

    Fan, Quan-Yong; Yang, Guang-Hong

    2016-01-01

    This paper is concerned with the problem of integral sliding-mode control for a class of nonlinear systems with input disturbances and unknown nonlinear terms through the adaptive actor-critic (AC) control method. The main objective is to design a sliding-mode control methodology based on the adaptive dynamic programming (ADP) method, so that the closed-loop system with time-varying disturbances is stable and the nearly optimal performance of the sliding-mode dynamics can be guaranteed. In the first step, a neural network (NN)-based observer and a disturbance observer are designed to approximate the unknown nonlinear terms and estimate the input disturbances, respectively. Based on the NN approximations and disturbance estimations, the discontinuous part of the sliding-mode control is constructed to eliminate the effect of the disturbances and attain the expected equivalent sliding-mode dynamics. Then, the ADP method with AC structure is presented to learn the optimal control for the sliding-mode dynamics online. Reconstructed tuning laws are developed to guarantee the stability of the sliding-mode dynamics and the convergence of the weights of critic and actor NNs. Finally, the simulation results are presented to illustrate the effectiveness of the proposed method.

  17. Adaptive Actor-Critic Design-Based Integral Sliding-Mode Control for Partially Unknown Nonlinear Systems With Input Disturbances.

    PubMed

    Fan, Quan-Yong; Yang, Guang-Hong

    2016-01-01

    This paper is concerned with the problem of integral sliding-mode control for a class of nonlinear systems with input disturbances and unknown nonlinear terms through the adaptive actor-critic (AC) control method. The main objective is to design a sliding-mode control methodology based on the adaptive dynamic programming (ADP) method, so that the closed-loop system with time-varying disturbances is stable and the nearly optimal performance of the sliding-mode dynamics can be guaranteed. In the first step, a neural network (NN)-based observer and a disturbance observer are designed to approximate the unknown nonlinear terms and estimate the input disturbances, respectively. Based on the NN approximations and disturbance estimations, the discontinuous part of the sliding-mode control is constructed to eliminate the effect of the disturbances and attain the expected equivalent sliding-mode dynamics. Then, the ADP method with AC structure is presented to learn the optimal control for the sliding-mode dynamics online. Reconstructed tuning laws are developed to guarantee the stability of the sliding-mode dynamics and the convergence of the weights of critic and actor NNs. Finally, the simulation results are presented to illustrate the effectiveness of the proposed method. PMID:26357411

  18. Cytopathology whole slide images and adaptive tutorials for postgraduate pathology trainees: a randomized crossover trial.

    PubMed

    Van Es, Simone L; Kumar, Rakesh K; Pryor, Wendy M; Salisbury, Elizabeth L; Velan, Gary M

    2015-09-01

    To determine whether cytopathology whole slide images and virtual microscopy adaptive tutorials aid learning by postgraduate trainees, we designed a randomized crossover trial to evaluate the quantitative and qualitative impact of whole slide images and virtual microscopy adaptive tutorials compared with traditional glass slide and textbook methods of learning cytopathology. Forty-three anatomical pathology registrars were recruited from Australia, New Zealand, and Malaysia. Online assessments were used to determine efficacy, whereas user experience and perceptions of efficiency were evaluated using online Likert scales and open-ended questions. Outcomes of online assessments indicated that, with respect to performance, learning with whole slide images and virtual microscopy adaptive tutorials was equivalent to using traditional methods. High-impact learning, efficiency, and equity of learning from virtual microscopy adaptive tutorials were strong themes identified in open-ended responses. Participants raised concern about the lack of z-axis capability in the cytopathology whole slide images, suggesting that delivery of z-stacked whole slide images online may be important for future educational development. In this trial, learning cytopathology with whole slide images and virtual microscopy adaptive tutorials was found to be as effective as and perceived as more efficient than learning from glass slides and textbooks. The use of whole slide images and virtual microscopy adaptive tutorials has the potential to provide equitable access to effective learning from teaching material of consistently high quality. It also has broader implications for continuing professional development and maintenance of competence and quality assurance in specialist practice.

  19. Anomaly Detection in Test Equipment via Sliding Mode Observers

    NASA Technical Reports Server (NTRS)

    Solano, Wanda M.; Drakunov, Sergey V.

    2012-01-01

    Nonlinear observers were originally developed based on the ideas of variable structure control, and for the purpose of detecting disturbances in complex systems. In this anomaly detection application, these observers were designed for estimating the distributed state of fluid flow in a pipe described by a class of advection equations. The observer algorithm uses collected data in a piping system to estimate the distributed system state (pressure and velocity along a pipe containing liquid gas propellant flow) using only boundary measurements. These estimates are then used to further estimate and localize possible anomalies such as leaks or foreign objects, and instrumentation metering problems such as incorrect flow meter orifice plate size. The observer algorithm has the following parts: a mathematical model of the fluid flow, observer control algorithm, and an anomaly identification algorithm. The main functional operation of the algorithm is in creating the sliding mode in the observer system implemented as software. Once the sliding mode starts in the system, the equivalent value of the discontinuous function in sliding mode can be obtained by filtering out the high-frequency chattering component. In control theory, "observers" are dynamic algorithms for the online estimation of the current state of a dynamic system by measurements of an output of the system. Classical linear observers can provide optimal estimates of a system state in case of uncertainty modeled by white noise. For nonlinear cases, the theory of nonlinear observers has been developed and its success is mainly due to the sliding mode approach. Using the mathematical theory of variable structure systems with sliding modes, the observer algorithm is designed in such a way that it steers the output of the model to the output of the system obtained via a variety of sensors, in spite of possible mismatches between the assumed model and actual system. The unique properties of sliding mode control

  20. Tensor Product Model Transformation Based Adaptive Integral-Sliding Mode Controller: Equivalent Control Method

    PubMed Central

    Zhao, Guoliang; Li, Hongxing

    2013-01-01

    This paper proposes new methodologies for the design of adaptive integral-sliding mode control. A tensor product model transformation based adaptive integral-sliding mode control law with respect to uncertainties and perturbations is studied, while upper bounds on the perturbations and uncertainties are assumed to be unknown. The advantage of proposed controllers consists in having a dynamical adaptive control gain to establish a sliding mode right at the beginning of the process. Gain dynamics ensure a reasonable adaptive gain with respect to the uncertainties. Finally, efficacy of the proposed controller is verified by simulations on an uncertain nonlinear system model. PMID:24453897

  1. Tensor product model transformation based adaptive integral-sliding mode controller: equivalent control method.

    PubMed

    Zhao, Guoliang; Sun, Kaibiao; Li, Hongxing

    2013-01-01

    This paper proposes new methodologies for the design of adaptive integral-sliding mode control. A tensor product model transformation based adaptive integral-sliding mode control law with respect to uncertainties and perturbations is studied, while upper bounds on the perturbations and uncertainties are assumed to be unknown. The advantage of proposed controllers consists in having a dynamical adaptive control gain to establish a sliding mode right at the beginning of the process. Gain dynamics ensure a reasonable adaptive gain with respect to the uncertainties. Finally, efficacy of the proposed controller is verified by simulations on an uncertain nonlinear system model.

  2. Real-time misfire detection via sliding mode observer

    NASA Astrophysics Data System (ADS)

    Wang, Yunsong; Chu, Fulei

    2005-07-01

    A new method to detect misfire in internal combustion engines is presented. It is based on the estimation of the cylinder deviation torque by using sliding mode observer. The input estimation problem is transformed into the control tracking problem. The sliding controller is utilised to continuously track the measured varying crank speed by changing the estimated deviation torque. During the process of tracking, the speed estimation errors decrease and the gradual stability of the dynamics is assured. The mean deviation torque during the power stroke derived from the estimated deviation torque can be employed to detect easily engine misfires. Experimental results for a four-cylinder engine indicate that the method is a suitable tool for real-time misfire detection on board vehicle under various working conditions.

  3. A fast converging robust controller using adaptive second order sliding mode.

    PubMed

    Mondal, Sanjoy; Mahanta, Chitralekha

    2012-11-01

    This paper proposes an adaptive second order sliding mode (SOSM) controller with a nonlinear sliding surface. The nonlinear sliding surface consists of a gain matrix having a variable damping ratio. Initially the sliding surface uses a low value of damping ratio to get a quick system response. As the closed loop system approaches the desired reference, the value of the damping ratio gets increased with an aim to reducing the overshoot and the settling time. The time derivative of the control signal is used to design the controller. The actual control input obtained by integrating the derivative control signal is smooth and chattering free. The adaptive tuning law used by the proposed controller eliminates the need of prior knowledge about the upper bound of system uncertainties. Simulation results demonstrate the effectiveness of the proposed control strategy.

  4. Adaptive uniform finite-/fixed-time convergent second-order sliding-mode control

    NASA Astrophysics Data System (ADS)

    Basin, Michael; Bharath Panathula, Chandrasekhara; Shtessel, Yuri

    2016-09-01

    This paper presents an adaptive gain algorithm for second-order sliding-mode control (2-SMC), specifically a super-twisting (STW)-like controller, with uniform finite/fixed convergence time, that is robust to perturbations with unknown bounds. It is shown that a second-order sliding mode is established as exact finite-time convergence to the origin if the adaptive gain does not have the ability to get reduced and converge to a small vicinity of the origin if the adaptation algorithm does not overestimate the control gain. The estimate of fixed convergence time of the studied adaptive STW-like controller is derived based on the Lyapunov analysis. The efficacy of the proposed adaptive algorithm is illustrated in a tutorial example, where the adaptive STW-like controller with uniform finite/fixed convergence time is compared to the adaptive STW controller with non-uniform finite convergence time.

  5. Adaptive sliding mode control of tethered satellite deployment with input limitation

    NASA Astrophysics Data System (ADS)

    Ma, Zhiqiang; Sun, Guanghui

    2016-10-01

    This paper proposes a novel adaptive sliding mode tension control method for the deployment of tethered satellite, where the input tension limitation is taken into account. The underactuated governing equations of the tethered satellites system are firstly derived based on Lagrangian mechanics theory. Considering the fact that the tether can only resist axial stretching, the tension input is modelled as input limitation. New adaptive sliding mode laws are addressed to guarantee the stability of the tethered satellite deployment with input disturbance, meanwhile to eliminate the effect of the limitation features of the tension input. Compared with the classic control strategy, the newly proposed adaptive sliding mode control law can deploy the satellite with smaller overshoot of the in-plane angle and implement the tension control reasonably and effectively in engineering practice. The numerical results validate the effectiveness of the proposed methods.

  6. Adaptive backstepping sliding mode control with fuzzy monitoring strategy for a kind of mechanical system.

    PubMed

    Song, Zhankui; Sun, Kaibiao

    2014-01-01

    A novel adaptive backstepping sliding mode control (ABSMC) law with fuzzy monitoring strategy is proposed for the tracking-control of a kind of nonlinear mechanical system. The proposed ABSMC scheme combining the sliding mode control and backstepping technique ensure that the occurrence of the sliding motion in finite-time and the trajectory of tracking-error converge to equilibrium point. To obtain a better perturbation rejection property, an adaptive control law is employed to compensate the lumped perturbation. Furthermore, we introduce fuzzy monitoring strategy to improve adaptive capacity and soften the control signal. The convergence and stability of the proposed control scheme are proved by using Lyaponov's method. Finally, numerical simulations demonstrate the effectiveness of the proposed control scheme.

  7. Bifurcations, chaos and adaptive backstepping sliding mode control of a power system with excitation limitation

    NASA Astrophysics Data System (ADS)

    Min, Fuhong; Wang, Yaoda; Peng, Guangya; Wang, Enrong; Auth, Jane A.

    2016-08-01

    The bifurcation and Lyapunov exponent for a single-machine-infinite bus system with excitation model are carried out by varying the mechanical power, generator damping factor and the exciter gain, from which periodic motions, chaos and the divergence of system are observed respectively. From given parameters and different initial conditions, the coexisting motions are developed in power system. The dynamic behaviors in power system may switch freely between the coexisting motions, which will bring huge security menace to protection operation. Especially, the angle divergences due to the break of stable chaotic oscillation are found which causes the instability of power system. Finally, a new adaptive backstepping sliding mode controller is designed which aims to eliminate the angle divergences and make the power system run in stable orbits. Numerical simulations are illustrated to verify the effectivity of the proposed method.

  8. Certainty equivalence adaptation combined with super-twisting sliding-mode control

    NASA Astrophysics Data System (ADS)

    Barth, A.; Reichhartinger, M.; Wulff, K.; Horn, M.; Reger, J.

    2016-09-01

    In this paper, a Lyapunov-based control concept is presented that combines variable structure and adaptive control. The considered system class consists of nonlinear single input systems which are affected by matched structured and unstructured uncertainties. Resorting to the certainty equivalence principle, the controller exploits advantages of both the sliding-mode and the adaptive control methodology. It is demonstrated that the gains of the discontinuous control action may be reduced remarkably when compared with pure sliding-mode-based approaches. The efficiency of the presented concept is demonstrated in detail, using results of numerical simulations.

  9. Observation and sliding mode observer for nonlinear fractional-order system with unknown input.

    PubMed

    Djeghali, Nadia; Djennoune, Said; Bettayeb, Maamar; Ghanes, Malek; Barbot, Jean-Pierre

    2016-07-01

    The main purpose of this paper is twofold. First, the observability and the left invertibility properties and the observable canonical form for nonlinear fractional-order systems are introduced. By using a transformation, we show that these properties can be deduced from an equivalent nonlinear integer-order system. Second, a step by step sliding mode observer for fault detection and estimation in nonlinear fractional-order systems is proposed. Starting with a chained fractional-order integrators form, a step by step first-order sliding mode observer is designed. The finite time convergence of the observer is established by using Lyapunov stability theory. A numerical example is given to illustrate the performance of the proposed approach.

  10. Sliding mode observer based incipient sensor fault detection with application to high-speed railway traction device.

    PubMed

    Zhang, Kangkang; Jiang, Bin; Yan, Xing-Gang; Mao, Zehui

    2016-07-01

    This paper considers incipient sensor fault detection issue for a class of nonlinear systems with "observer unmatched" uncertainties. A particular fault detection sliding mode observer is designed for the augmented system formed by the original system and incipient sensor faults. The designed parameters are obtained using LMI and line filter techniques to guarantee that the generated residuals are robust to uncertainties and that sliding motion is not destroyed by faults. Then, three levels of novel adaptive thresholds are proposed based on the reduced order sliding mode dynamics, which effectively improve incipient sensor faults detectability. Case study of on the traction system in China Railway High-speed is presented to demonstrate the effectiveness of the proposed incipient senor faults detection schemes. PMID:27156675

  11. Sliding mode observer based incipient sensor fault detection with application to high-speed railway traction device.

    PubMed

    Zhang, Kangkang; Jiang, Bin; Yan, Xing-Gang; Mao, Zehui

    2016-07-01

    This paper considers incipient sensor fault detection issue for a class of nonlinear systems with "observer unmatched" uncertainties. A particular fault detection sliding mode observer is designed for the augmented system formed by the original system and incipient sensor faults. The designed parameters are obtained using LMI and line filter techniques to guarantee that the generated residuals are robust to uncertainties and that sliding motion is not destroyed by faults. Then, three levels of novel adaptive thresholds are proposed based on the reduced order sliding mode dynamics, which effectively improve incipient sensor faults detectability. Case study of on the traction system in China Railway High-speed is presented to demonstrate the effectiveness of the proposed incipient senor faults detection schemes.

  12. Non-linear adaptive sliding mode switching control with average dwell-time

    NASA Astrophysics Data System (ADS)

    Yu, Lei; Zhang, Maoqing; Fei, Shumin

    2013-03-01

    In this article, an adaptive integral sliding mode control scheme is addressed for switched non-linear systems in the presence of model uncertainties and external disturbances. The control law includes two parts: a slide mode controller for the reduced model of the plant and a compensation controller to deal with the non-linear systems with parameter uncertainties. The adaptive updated laws have been derived from the switched multiple Lyapunov function method, also an admissible switching signal with average dwell-time technique is given. The simplicity of the proposed control scheme facilitates its implementation and the overall control scheme guarantees the global asymptotic stability in the Lyapunov sense such that the sliding surface of the control system is well reached. Simulation results are presented to demonstrate the effectiveness and the feasibility of the proposed approach.

  13. Adaptive fuzzy switched swing-up and sliding control for the double-pendulum-and-cart system.

    PubMed

    Tao, Chin Wang; Taur, Jinshiuh; Chang, J H; Su, Shun-Feng

    2010-02-01

    In this paper, an adaptive fuzzy switched swing-up and sliding controller (AFSSSC) is proposed for the swing-up and position controls of a double-pendulum-and-cart system. The proposed AFSSSC consists of a fuzzy switching controller (FSC), an adaptive fuzzy swing-up controller (FSUC), and an adaptive hybrid fuzzy sliding controller (HFSC). To simplify the design of the adaptive HFSC, the double-pendulum-and-cart system is reformulated as a double-pendulum and a cart subsystem with matched time-varying uncertainties. In addition, an adaptive mechanism is provided to learn the parameters of the output fuzzy sets for the adaptive HFSC. The FSC is designed to smoothly switch between the adaptive FSUC and the adaptive HFSC. Moreover, the sliding mode and the stability of the fuzzy sliding control systems are guaranteed. Simulation results are included to illustrate the effectiveness of the proposed AFSSSC. PMID:19661002

  14. An adaptive supervisory sliding fuzzy cerebellar model articulation controller for sensorless vector-controlled induction motor drive systems.

    PubMed

    Wang, Shun-Yuan; Tseng, Chwan-Lu; Lin, Shou-Chuang; Chiu, Chun-Jung; Chou, Jen-Hsiang

    2015-01-01

    This paper presents the implementation of an adaptive supervisory sliding fuzzy cerebellar model articulation controller (FCMAC) in the speed sensorless vector control of an induction motor (IM) drive system. The proposed adaptive supervisory sliding FCMAC comprised a supervisory controller, integral sliding surface, and an adaptive FCMAC. The integral sliding surface was employed to eliminate steady-state errors and enhance the responsiveness of the system. The adaptive FCMAC incorporated an FCMAC with a compensating controller to perform a desired control action. The proposed controller was derived using the Lyapunov approach, which guarantees learning-error convergence. The implementation of three intelligent control schemes--the adaptive supervisory sliding FCMAC, adaptive sliding FCMAC, and adaptive sliding CMAC--were experimentally investigated under various conditions in a realistic sensorless vector-controlled IM drive system. The root mean square error (RMSE) was used as a performance index to evaluate the experimental results of each control scheme. The analysis results indicated that the proposed adaptive supervisory sliding FCMAC substantially improved the system performance compared with the other control schemes. PMID:25815450

  15. An Adaptive Supervisory Sliding Fuzzy Cerebellar Model Articulation Controller for Sensorless Vector-Controlled Induction Motor Drive Systems

    PubMed Central

    Wang, Shun-Yuan; Tseng, Chwan-Lu; Lin, Shou-Chuang; Chiu, Chun-Jung; Chou, Jen-Hsiang

    2015-01-01

    This paper presents the implementation of an adaptive supervisory sliding fuzzy cerebellar model articulation controller (FCMAC) in the speed sensorless vector control of an induction motor (IM) drive system. The proposed adaptive supervisory sliding FCMAC comprised a supervisory controller, integral sliding surface, and an adaptive FCMAC. The integral sliding surface was employed to eliminate steady-state errors and enhance the responsiveness of the system. The adaptive FCMAC incorporated an FCMAC with a compensating controller to perform a desired control action. The proposed controller was derived using the Lyapunov approach, which guarantees learning-error convergence. The implementation of three intelligent control schemes—the adaptive supervisory sliding FCMAC, adaptive sliding FCMAC, and adaptive sliding CMAC—were experimentally investigated under various conditions in a realistic sensorless vector-controlled IM drive system. The root mean square error (RMSE) was used as a performance index to evaluate the experimental results of each control scheme. The analysis results indicated that the proposed adaptive supervisory sliding FCMAC substantially improved the system performance compared with the other control schemes. PMID:25815450

  16. Sliding mode output feedback control based on tracking error observer with disturbance estimator.

    PubMed

    Xiao, Lingfei; Zhu, Yue

    2014-07-01

    For a class of systems who suffers from disturbances, an original output feedback sliding mode control method is presented based on a novel tracking error observer with disturbance estimator. The mathematical models of the systems are not required to be with high accuracy, and the disturbances can be vanishing or nonvanishing, while the bounds of disturbances are unknown. By constructing a differential sliding surface and employing reaching law approach, a sliding mode controller is obtained. On the basis of an extended disturbance estimator, a creative tracking error observer is produced. By using the observation of tracking error and the estimation of disturbance, the sliding mode controller is implementable. It is proved that the disturbance estimation error and tracking observation error are bounded, the sliding surface is reachable and the closed-loop system is robustly stable. The simulations on a servomotor positioning system and a five-degree-of-freedom active magnetic bearings system verify the effect of the proposed method.

  17. Robust Second Order Sliding mode Observer for the Estimation of the Vehicle States

    NASA Astrophysics Data System (ADS)

    Chaibet, A.; Nouveliere, L.; Hima, S.; Mammar, S.

    2008-06-01

    This paper is dedicated to the observation of non measurable variables for automotive systems. A non linear observer, based on a sliding mode approach, is presented for the estimation of the dynamic states of the vehicle. The considered technique is applied to the estimation problem for an automated vehicle following. Both the simulation and the experimental results are addressed to demonstrate the effectiveness of the sliding mode observer for different maneuvers, in terms of performances and robustness.

  18. Adaptive discrete-time sliding-mode control of nonlinear systems described by Wiener models

    NASA Astrophysics Data System (ADS)

    Salhi, Houda; Kamoun, Samira; Essounbouli, Najib; Hamzaoui, Abdelaziz

    2016-03-01

    In this paper, we propose an adaptive control scheme that can be applied to nonlinear systems with unknown parameters. The considered class of nonlinear systems is described by the block-oriented models, specifically, the Wiener models. These models consist of dynamic linear blocks in series with static nonlinear blocks. The proposed adaptive control method is based on the inverse of the nonlinear function block and on the discrete-time sliding-mode controller. The parameters adaptation are performed using a new recursive parametric estimation algorithm. This algorithm is developed using the adjustable model method and the least squares technique. A recursive least squares (RLS) algorithm is used to estimate the inverse nonlinear function. A time-varying gain is proposed, in the discrete-time sliding mode controller, to reduce the chattering problem. The stability of the closed-loop nonlinear system, with the proposed adaptive control scheme, has been proved. An application to a pH neutralisation process has been carried out and the simulation results clearly show the effectiveness of the proposed adaptive control scheme.

  19. Design of adaptive fuzzy wavelet neural sliding mode controller for uncertain nonlinear systems.

    PubMed

    Shahriari kahkeshi, Maryam; Sheikholeslam, Farid; Zekri, Maryam

    2013-05-01

    This paper proposes novel adaptive fuzzy wavelet neural sliding mode controller (AFWN-SMC) for a class of uncertain nonlinear systems. The main contribution of this paper is to design smooth sliding mode control (SMC) for a class of high-order nonlinear systems while the structure of the system is unknown and no prior knowledge about uncertainty is available. The proposed scheme composed of an Adaptive Fuzzy Wavelet Neural Controller (AFWNC) to construct equivalent control term and an Adaptive Proportional-Integral (A-PI) controller for implementing switching term to provide smooth control input. Asymptotical stability of the closed loop system is guaranteed, using the Lyapunov direct method. To show the efficiency of the proposed scheme, some numerical examples are provided. To validate the results obtained by proposed approach, some other methods are adopted from the literature and applied for comparison. Simulation results show superiority and capability of the proposed controller to improve the steady state performance and transient response specifications by using less numbers of fuzzy rules and on-line adaptive parameters in comparison to other methods. Furthermore, control effort has considerably decreased and chattering phenomenon has been completely removed.

  20. Functional Based Adaptive and Fuzzy Sliding Controller for Non-Autonomous Active Suspension System

    NASA Astrophysics Data System (ADS)

    Huang, Shiuh-Jer; Chen, Hung-Yi

    In this paper, an adaptive sliding controller is developed for controlling a vehicle active suspension system. The functional approximation technique is employed to substitute the unknown non-autonomous functions of the suspension system and release the model-based requirement of sliding mode control algorithm. In order to improve the control performance and reduce the implementation problem, a fuzzy strategy with online learning ability is added to compensate the functional approximation error. The update laws of the functional approximation coefficients and the fuzzy tuning parameters are derived from the Lyapunov theorem to guarantee the system stability. The proposed controller is implemented on a quarter-car hydraulic actuating active suspension system test-rig. The experimental results show that the proposed controller suppresses the oscillation amplitude of the suspension system effectively.

  1. Surface bound or cytoplasmic immunoglobulins: interpretation of the immunofluorescence observed in cytocentrifuge slides of human lymphocytes.

    PubMed Central

    Schuit, H R; Hijmans, W; Jansen, J

    1984-01-01

    Results of immunofluorescence observations in the study of normal and malignant blood lymphocytes are described. Data which support the proposition that most membrane bound immunoglobulin molecules are stable enough to remain intact during cytocentrifuge slide preparation are presented. Therefore not all positive cells in a fixed cytocentrifuge slide should be considered as containing cytoplasmic immunoglobulins. A correct interpretation is essential because of its bearing on our concepts of B lymphocyte differentiation. Images Fig. 3 PMID:6378456

  2. Fault-tolerant nonlinear adaptive flight control using sliding mode online learning.

    PubMed

    Krüger, Thomas; Schnetter, Philipp; Placzek, Robin; Vörsmann, Peter

    2012-08-01

    An expanded nonlinear model inversion flight control strategy using sliding mode online learning for neural networks is presented. The proposed control strategy is implemented for a small unmanned aircraft system (UAS). This class of aircraft is very susceptible towards nonlinearities like atmospheric turbulence, model uncertainties and of course system failures. Therefore, these systems mark a sensible testbed to evaluate fault-tolerant, adaptive flight control strategies. Within this work the concept of feedback linearization is combined with feed forward neural networks to compensate for inversion errors and other nonlinear effects. Backpropagation-based adaption laws of the network weights are used for online training. Within these adaption laws the standard gradient descent backpropagation algorithm is augmented with the concept of sliding mode control (SMC). Implemented as a learning algorithm, this nonlinear control strategy treats the neural network as a controlled system and allows a stable, dynamic calculation of the learning rates. While considering the system's stability, this robust online learning method therefore offers a higher speed of convergence, especially in the presence of external disturbances. The SMC-based flight controller is tested and compared with the standard gradient descent backpropagation algorithm in the presence of system failures.

  3. A vehicle ABS adaptive sliding-mode control algorithm based on the vehicle velocity estimation and tyre/road friction coefficient estimations

    NASA Astrophysics Data System (ADS)

    Zhang, Xiangwen; Xu, Yong; Pan, Ming; Ren, Fenghua

    2014-04-01

    A sliding-mode observer is designed to estimate the vehicle velocity with the measured vehicle acceleration, the wheel speeds and the braking torques. Based on the Burckhardt tyre model, the extended Kalman filter is designed to estimate the parameters of the Burckhardt model with the estimated vehicle velocity, the measured wheel speeds and the vehicle acceleration. According to the estimated parameters of the Burckhardt tyre model, the tyre/road friction coefficients and the optimal slip ratios are calculated. A vehicle adaptive sliding-mode control (SMC) algorithm is presented with the estimated vehicle velocity, the tyre/road friction coefficients and the optimal slip ratios. And the adjustment method of the sliding-mode gain factors is discussed. Based on the adaptive SMC algorithm, a vehicle's antilock braking system (ABS) control system model is built with the Simulink Toolbox. Under the single-road condition as well as the different road conditions, the performance of the vehicle ABS system is simulated with the vehicle velocity observer, the tyre/road friction coefficient estimator and the adaptive SMC algorithm. The results indicate that the estimated errors of the vehicle velocity and the tyre/road friction coefficients are acceptable and the vehicle ABS adaptive SMC algorithm is effective. So the proposed adaptive SMC algorithm can be used to control the vehicle ABS without the information of the vehicle velocity and the road conditions.

  4. Reducing False Negative Reads in RFID Data Streams Using an Adaptive Sliding-Window Approach

    PubMed Central

    Massawe, Libe Valentine; Kinyua, Johnson D. M.; Vermaak, Herman

    2012-01-01

    Unreliability of the data streams generated by RFID readers is among the primary factors which limit the widespread adoption of the RFID technology. RFID data cleaning is, therefore, an essential task in the RFID middleware systems in order to reduce reading errors, and to allow these data streams to be used to make a correct interpretation and analysis of the physical world they are representing. In this paper we propose an adaptive sliding-window based approach called WSTD which is capable of efficiently coping with both environmental variation and tag dynamics. Our experimental results demonstrate the efficacy of the proposed approach. PMID:22666027

  5. Robust dynamic sliding-mode control using adaptive RENN for magnetic levitation system.

    PubMed

    Lin, Faa-Jeng; Chen, Syuan-Yi; Shyu, Kuo-Kai

    2009-06-01

    In this paper, a robust dynamic sliding mode control system (RDSMC) using a recurrent Elman neural network (RENN) is proposed to control the position of a levitated object of a magnetic levitation system considering the uncertainties. First, a dynamic model of the magnetic levitation system is derived. Then, a proportional-integral-derivative (PID)-type sliding-mode control system (SMC) is adopted for tracking of the reference trajectories. Moreover, a new PID-type dynamic sliding-mode control system (DSMC) is proposed to reduce the chattering phenomenon. However, due to the hardware being limited and the uncertainty bound being unknown of the switching function for the DSMC, an RDSMC is proposed to improve the control performance and further increase the robustness of the magnetic levitation system. In the RDSMC, an RENN estimator is used to estimate an unknown nonlinear function of lumped uncertainty online and replace the switching function in the hitting control of the DSMC directly. The adaptive learning algorithms that trained the parameters of the RENN online are derived using Lyapunov stability theorem. Furthermore, a robust compensator is proposed to confront the uncertainties including approximation error, optimal parameter vectors, and higher order terms in Taylor series. Finally, some experimental results of tracking the various periodic trajectories demonstrate the validity of the proposed RDSMC for practical applications. PMID:19423437

  6. Unknown Input and Sensor Fault Estimation Using Sliding-Mode Observers

    SciTech Connect

    Kalsi, Karanjit; Hui, Stefen; Zak, Stanislaw

    2011-06-29

    Sliding-mode observers are used to construct unknown input estimators. Then, these unknown input estimators are combined with sensor fault estimation schemes into one architecture that employs two sliding-mode observers for simultaneously estimating the plant’s actuator faults (part of the unknown input) and detecting sensor faults. Closed form expressions are presented for the estimates of unknown inputs and sensor faults. A benchmark example of a controlled inverted pendulum system from the literature is utilized in the simulation study. The study shows that the observers analyzed in this paper generate good estimates of the unknown input and sensor faults signals in noisy environments for nonlinear plants.

  7. Speed tracking and synchronization of multiple motors using ring coupling control and adaptive sliding mode control.

    PubMed

    Li, Le-Bao; Sun, Ling-Ling; Zhang, Sheng-Zhou; Yang, Qing-Quan

    2015-09-01

    A new control approach for speed tracking and synchronization of multiple motors is developed, by incorporating an adaptive sliding mode control (ASMC) technique into a ring coupling synchronization control structure. This control approach can stabilize speed tracking of each motor and synchronize its motion with other motors' motion so that speed tracking errors and synchronization errors converge to zero. Moreover, an adaptive law is exploited to estimate the unknown bound of uncertainty, which is obtained in the sense of Lyapunov stability theorem to minimize the control effort and attenuate chattering. Performance comparisons with parallel control, relative coupling control and conventional PI control are investigated on a four-motor synchronization control system. Extensive simulation results show the effectiveness of the proposed control scheme.

  8. Cytopathology whole slide images and virtual microscopy adaptive tutorials: A software pilot

    PubMed Central

    Van Es, Simone L.; Pryor, Wendy M.; Belinson, Zack; Salisbury, Elizabeth L.; Velan, Gary M.

    2015-01-01

    Background: The constant growth in the body of knowledge in medicine requires pathologists and pathology trainees to engage in continuing education. Providing them with equitable access to efficient and effective forms of education in pathology (especially in remote and rural settings) is important, but challenging. Methods: We developed three pilot cytopathology virtual microscopy adaptive tutorials (VMATs) to explore a novel adaptive E-learning platform (AeLP) which can incorporate whole slide images for pathology education. We collected user feedback to further develop this educational material and to subsequently deploy randomized trials in both pathology specialist trainee and also medical student cohorts. Cytopathology whole slide images were first acquired then novel VMATs teaching cytopathology were created using the AeLP, an intelligent tutoring system developed by Smart Sparrow. The pilot was run for Australian pathologists and trainees through the education section of Royal College of Pathologists of Australasia website over a period of 9 months. Feedback on the usability, impact on learning and any technical issues was obtained using 5-point Likert scale items and open-ended feedback in online questionnaires. Results: A total of 181 pathologists and pathology trainees anonymously attempted the three adaptive tutorials, a smaller proportion of whom went on to provide feedback at the end of each tutorial. VMATs were perceived as effective and efficient E-learning tools for pathology education. User feedback was positive. There were no significant technical issues. Conclusion: During this pilot, the user feedback on the educational content and interface and the lack of technical issues were helpful. Large scale trials of similar online cytopathology adaptive tutorials were planned for the future. PMID:26605119

  9. A New Controller for PMSM Servo Drive Based on the Sliding Mode Approach with Parameter Adaptation

    NASA Astrophysics Data System (ADS)

    Gjini, Orges; Kaneko, Takayuki; Ohsawa, Hiroshi

    A novel controller based on the Sliding Mode (SM) approach is designed for controlling a permanent magnet synchronous motor (PMSM) in a servo drive. After analyzing the classical SM controller, changes are made in the controller design such that its performance is substantially improved. To improve the controller performance in steady state (zero error positioning) an integral block is added to the controller resulting in a new controller configuration, which we call Sliding Mode Integral (SMI) controller. The new controller is tuned based on the results from parameter identification of the motor and the working machine. To cope with model parameter variations, especially unpredictable friction changes, gain scheduling and fuzzy based adaptive techniques are used in the control algorithm. Experiments and simulations are carried out and their results show a high performance control. The new controller offers very good tracking; it is highly robust, reaches the final position very fast and has a large stall torque. Furthermore the application of the SM ensures reduction of the system order by one. For comparison, the new controller's performance is compared with that of a PI controller. From the experimental results it is obvious the superiority of the new proposed controller.

  10. Decentralized adaptive sliding mode control for beam synchronization of tethered InSAR system

    NASA Astrophysics Data System (ADS)

    Zhang, Jinxiu; Zhang, Zhigang; Wu, Baolin

    2016-10-01

    Beam synchronization problem of tethered interferometric synthetic aperture radar (InSAR) is addressed in this paper. Two antennas of the system are carried by separate satellites connected through a tether to obtain a preferable baseline. A Total Zero Doppler Steering (TZDS) is implemented to mother-satellite to cancel the residual Doppler. Subsequently attitude reference trajectories for the two satellites are generated to achieve the beam synchronization and TZDS. Thereafter, a decentralized adaptive sliding mode control law is proposed to track these reference trajectories in the presence of model uncertainties and external disturbances. Finally, the stability of closed-loop system is proved by the corollary of Barbalat's Lemma. Simulation results show the proposed control law is effective to achieve beam synchronization of the system.

  11. Adaptive sliding control of non-autonomous active suspension systems with time-varying loadings

    NASA Astrophysics Data System (ADS)

    Chen, Po-Chang; Huang, An-Chyau

    2005-04-01

    An adaptive sliding controller is proposed in this paper for controlling a non-autonomous quarter-car suspension system with time-varying loadings. The bound of the car-body loading is assumed to be available. Then, the reference coordinate is placed at the static position under the nominal loading so that the system dynamic equation is derived. Due to spring nonlinearities, the system property becomes asymmetric after coordinate transformation. Besides, in practical cases, system parameters are not easy to be obtained precisely for controller design. Therefore, in this paper, system uncertainties are lumped into two unknown time-varying functions. Since the variation bound of one of the unknown functions is not available, conventional adaptive schemes and robust designs are not applicable. To deal with this problem, the function approximation technique is employed to represent the unknown function as a finite combination of basis functions. The Lyapunov direct method can thus be used to find adaptive laws for updating coefficients in the approximating series and to prove stability of the closed-loop system. Since the position and velocity measurements of the unsprung mass are lumped into the unknown function, there is no need to install sensors on the axle and wheel assembly in the actual implementation. Simulation results are presented to show the performance of the proposed strategy.

  12. Adaptation of Vocational Education Programs for Special Needs: A Slide/Tape Presentation. Final Report. Research Series Number 62.

    ERIC Educational Resources Information Center

    North Dakota Univ., Grand Forks. Dept. of Home Economics and Nutrition.

    A slide/tape series entitled "Vocational Education and the Special Needs Student" was developed in North Dakota to illustrate adaptations that vocational education teachers have made for special needs students (mentally handicapped, physically handicapped, and disadvantaged) and to serve as a basis for discussion at inservice and preservice levels…

  13. Mean deviation coupling synchronous control for multiple motors via second-order adaptive sliding mode control.

    PubMed

    Li, Lebao; Sun, Lingling; Zhang, Shengzhou

    2016-05-01

    A new mean deviation coupling synchronization control strategy is developed for multiple motor control systems, which can guarantee the synchronization performance of multiple motor control systems and reduce complexity of the control structure with the increasing number of motors. The mean deviation coupling synchronization control architecture combining second-order adaptive sliding mode control (SOASMC) approach is proposed, which can improve synchronization control precision of multiple motor control systems and make speed tracking errors, mean speed errors of each motor and speed synchronization errors converge to zero rapidly. The proposed control scheme is robustness to parameter variations and random external disturbances and can alleviate the chattering phenomena. Moreover, an adaptive law is employed to estimate the unknown bound of uncertainty, which is obtained in the sense of Lyapunov stability theorem to minimize the control effort. Performance comparisons with master-slave control, relative coupling control, ring coupling control, conventional PI control and SMC are investigated on a four-motor synchronization control system. Extensive comparative results are given to shown the good performance of the proposed control scheme. PMID:26899554

  14. 6-DOF robust adaptive terminal sliding mode control for spacecraft formation flying

    NASA Astrophysics Data System (ADS)

    Wang, Jianying; Sun, Zhaowei

    2012-04-01

    This paper addresses the tracking control problem of the leader-follower spacecraft formation, by which we mean that the relative motion between the leader and the follower is required to track a desired time-varying trajectory given in advance. Using dual number, the six-degree-of-freedom motion of the follower spacecraft relative to the leader spacecraft is modeled, where the coupling effect between the translational motion and the rotational one is accounted. A robust adaptive terminal sliding mode control law, including the adaptive algorithms, is proposed to ensure the finite time convergence of the relative motion tracking errors despite the presence of model uncertainties and external disturbances, based on which a modified controller is furthermore developed to solve the dual-equilibrium problem caused by dual quaternion representation. In addition, to alleviate the chattering, hyperbolic tangent function is adopted to substitute for the sign function. And by theoretical analysis, it is proved that the tracking error in such case will converge to a neighborhood of the origin in finite time. Finally, numerical simulations are performed to demonstrate the validity of the proposed approaches.

  15. Mean deviation coupling synchronous control for multiple motors via second-order adaptive sliding mode control.

    PubMed

    Li, Lebao; Sun, Lingling; Zhang, Shengzhou

    2016-05-01

    A new mean deviation coupling synchronization control strategy is developed for multiple motor control systems, which can guarantee the synchronization performance of multiple motor control systems and reduce complexity of the control structure with the increasing number of motors. The mean deviation coupling synchronization control architecture combining second-order adaptive sliding mode control (SOASMC) approach is proposed, which can improve synchronization control precision of multiple motor control systems and make speed tracking errors, mean speed errors of each motor and speed synchronization errors converge to zero rapidly. The proposed control scheme is robustness to parameter variations and random external disturbances and can alleviate the chattering phenomena. Moreover, an adaptive law is employed to estimate the unknown bound of uncertainty, which is obtained in the sense of Lyapunov stability theorem to minimize the control effort. Performance comparisons with master-slave control, relative coupling control, ring coupling control, conventional PI control and SMC are investigated on a four-motor synchronization control system. Extensive comparative results are given to shown the good performance of the proposed control scheme.

  16. Current Sensor Fault Diagnosis Based on a Sliding Mode Observer for PMSM Driven Systems

    PubMed Central

    Huang, Gang; Luo, Yi-Ping; Zhang, Chang-Fan; Huang, Yi-Shan; Zhao, Kai-Hui

    2015-01-01

    This paper proposes a current sensor fault detection method based on a sliding mode observer for the torque closed-loop control system of interior permanent magnet synchronous motors. First, a sliding mode observer based on the extended flux linkage is built to simplify the motor model, which effectively eliminates the phenomenon of salient poles and the dependence on the direct axis inductance parameter, and can also be used for real-time calculation of feedback torque. Then a sliding mode current observer is constructed in αβ coordinates to generate the fault residuals of the phase current sensors. The method can accurately identify abrupt gain faults and slow-variation offset faults in real time in faulty sensors, and the generated residuals of the designed fault detection system are not affected by the unknown input, the structure of the observer, and the theoretical derivation and the stability proof process are concise and simple. The RT-LAB real-time simulation is used to build a simulation model of the hardware in the loop. The simulation and experimental results demonstrate the feasibility and effectiveness of the proposed method. PMID:25970258

  17. Current Sensor Fault Diagnosis Based on a Sliding Mode Observer for PMSM Driven Systems.

    PubMed

    Huang, Gang; Luo, Yi-Ping; Zhang, Chang-Fan; Huang, Yi-Shan; Zhao, Kai-Hui

    2015-01-01

    This paper proposes a current sensor fault detection method based on a sliding mode observer for the torque closed-loop control system of interior permanent magnet synchronous motors. First, a sliding mode observer based on the extended flux linkage is built to simplify the motor model, which effectively eliminates the phenomenon of salient poles and the dependence on the direct axis inductance parameter, and can also be used for real-time calculation of feedback torque. Then a sliding mode current observer is constructed in αβ coordinates to generate the fault residuals of the phase current sensors. The method can accurately identify abrupt gain faults and slow-variation offset faults in real time in faulty sensors, and the generated residuals of the designed fault detection system are not affected by the unknown input, the structure of the observer, and the theoretical derivation and the stability proof process are concise and simple. The RT-LAB real-time simulation is used to build a simulation model of the hardware in the loop. The simulation and experimental results demonstrate the feasibility and effectiveness of the proposed method. PMID:25970258

  18. Current Sensor Fault Diagnosis Based on a Sliding Mode Observer for PMSM Driven Systems.

    PubMed

    Huang, Gang; Luo, Yi-Ping; Zhang, Chang-Fan; Huang, Yi-Shan; Zhao, Kai-Hui

    2015-05-11

    This paper proposes a current sensor fault detection method based on a sliding mode observer for the torque closed-loop control system of interior permanent magnet synchronous motors. First, a sliding mode observer based on the extended flux linkage is built to simplify the motor model, which effectively eliminates the phenomenon of salient poles and the dependence on the direct axis inductance parameter, and can also be used for real-time calculation of feedback torque. Then a sliding mode current observer is constructed in αβ coordinates to generate the fault residuals of the phase current sensors. The method can accurately identify abrupt gain faults and slow-variation offset faults in real time in faulty sensors, and the generated residuals of the designed fault detection system are not affected by the unknown input, the structure of the observer, and the theoretical derivation and the stability proof process are concise and simple. The RT-LAB real-time simulation is used to build a simulation model of the hardware in the loop. The simulation and experimental results demonstrate the feasibility and effectiveness of the proposed method.

  19. Sensorless sliding mode observer for a five-phase permanent magnet synchronous motor drive.

    PubMed

    Hosseyni, Anissa; Trabelsi, Ramzi; Mimouni, Med Faouzi; Iqbal, Atif; Alammari, Rashid

    2015-09-01

    This paper deals with the sensorless vector controlled five-phase permanent magnet synchronous motor (PMSM) drive based on a sliding mode observer (SMO). The observer is designed considering the back electromotive force (EMF) of five-phase permanent magnet synchronous motor. The SMO structure and design are illustrated. Stability of the proposed observer is demonstrated using Lyapunov stability criteria. The proposed strategy is asymptotically stable in the context of Lyapunov theory. Simulated results on a five-phase PMSM drive are displayed to validate the feasibility and the effectiveness of the proposed control strategy.

  20. Sensorless control of ship propulsion interior permanent magnet synchronous motor based on a new sliding mode observer.

    PubMed

    Ren, Jun-Jie; Liu, Yan-Cheng; Wang, Ning; Liu, Si-Yuan

    2015-01-01

    This paper proposes a sensorless speed control strategy for ship propulsion interior permanent magnet synchronous motor (IPMSM) based on a new sliding-mode observer (SMO). In the SMO the low-pass filter and the method of arc-tangent calculation of extended electromotive force (EMF) or phase-locked loop (PLL) technique are not used. The calculation of the rotor speed is deduced from the Lyapunov function stability analysis. In order to reduce system chattering, sigmoid functions with switching gains being adaptively updated by fuzzy logic systems are innovatively incorporated into the SMO. Finally, simulation results for a 4.088 MW ship propulsion IPMSM and experimental results from a 7.5 kW IPMSM drive are provided to verify the effectiveness of the proposed SMO method.

  1. Adaptive dual-layer super-twisting control and observation

    NASA Astrophysics Data System (ADS)

    Edwards, Christopher; Shtessel, Yuri

    2016-09-01

    In this paper, a super-twisting-like structure with adaptive gains is proposed. The structure is parameterised by two scalar gains, both of which adapt, and by an additional time-varying term. The magnitudes of the adaptive terms are allowed to both increase and decrease as appropriate so that they are as small as possible, in the sense that they do not unnecessarily over-bound the uncertainty, and yet are large enough to sustain a sliding motion. In the paper, a new time varying gain is incorporated into the traditional super-twisting architecture. The proposed adaption law has a dual-layer structure which is formally analyzed using Lyapunov techniques. The additional term has the effect of simplifying the stability analysis whilst guaranteeing the second-order sliding mode properties of the traditional super-twisting scheme.

  2. In situ observation of a hydrogel-glass interface during sliding friction.

    PubMed

    Yamamoto, Tetsurou; Kurokawa, Takayuki; Ahmed, Jamil; Kamita, Gen; Yashima, Shintaro; Furukawa, Yuichiro; Ota, Yuko; Furukawa, Hidemitsu; Gong, Jian Ping

    2014-08-14

    Direct observation of hydrogel contact with a solid surface in water is indispensable for understanding the friction, lubrication, and adhesion of hydrogels under water. However, this is a difficult task since the refractive index of hydrogels is very close to that of water. In this paper, we present a novel method to in situ observe the macroscopic contact of hydrogels with a solid surface based on the principle of critical refraction. This method was applied to investigate the sliding friction of a polyacrylamide (PAAm) hydrogel with glass by using a strain-controlled parallel-plate rheometer. The study revealed that when the compressive pressure is not very high, the hydrogel forms a heterogeneous contact with the glass, and a macro-scale water drop is trapped at the soft interface. The pre-trapped water spreads over the interface to decrease the contact area with the increase in sliding velocity, which dramatically reduces the friction of the hydrogel. The study also revealed that this heterogeneous contact is the reason for the poor reproducibility of hydrogel friction that has been often observed in previous studies. Under the condition of homogeneous full contact, the molecular origin of hydrogel friction in water is discussed. This study highlights the importance of direct interfacial observation to reveal the friction mechanism of hydrogels.

  3. Sliding mode based trajectory linearization control for hypersonic reentry vehicle via extended disturbance observer.

    PubMed

    Xingling, Shao; Honglun, Wang

    2014-11-01

    This paper proposes a novel hybrid control framework by combing observer-based sliding mode control (SMC) with trajectory linearization control (TLC) for hypersonic reentry vehicle (HRV) attitude tracking problem. First, fewer control consumption is achieved using nonlinear tracking differentiator (TD) in the attitude loop. Second, a novel SMC that employs extended disturbance observer (EDO) to counteract the effect of uncertainties using a new sliding surface which includes the estimation error is integrated to address the tracking error stabilization issues in the attitude and angular rate loop, respectively. In addition, new results associated with EDO are examined in terms of dynamic response and noise-tolerant performance, as well as estimation accuracy. The key feature of the proposed compound control approach is that chattering free tracking performance with high accuracy can be ensured for HRV in the presence of multiple uncertainties under control constraints. Based on finite time convergence stability theory, the stability of the resulting closed-loop system is well established. Also, comparisons and extensive simulation results are presented to demonstrate the effectiveness of the control strategy.

  4. A reduced-order nonlinear sliding mode observer for vehicle slip angle and tyre forces

    NASA Astrophysics Data System (ADS)

    Chen, Yuhang; Ji, Yunfeng; Guo, Konghui

    2014-12-01

    In this paper, a reduced-order sliding mode observer (RO-SMO) is developed for vehicle state estimation. Several improvements are achieved in this paper. First, the reference model accuracy is improved by considering vehicle load transfers and using a precise nonlinear tyre model 'UniTire'. Second, without the reference model accuracy degraded, the computing burden of the state observer is decreased by a reduced-order approach. Third, nonlinear system damping is integrated into the SMO to speed convergence and reduce chattering. The proposed RO-SMO is evaluated through simulation and experiments based on an in-wheel motor electric vehicle. The results show that the proposed observer accurately predicts the vehicle states.

  5. A novel adaptive switching function on fault tolerable sliding mode control for uncertain stochastic systems.

    PubMed

    Zahiripour, Seyed Ali; Jalali, Ali Akbar

    2014-09-01

    A novel switching function based on an optimization strategy for the sliding mode control (SMC) method has been provided for uncertain stochastic systems subject to actuator degradation such that the closed-loop system is globally asymptotically stable with probability one. In the previous researches the focus on sliding surface has been on proportional or proportional-integral function of states. In this research, from a degree of freedom that depends on designer choice is used to meet certain objectives. In the design of the switching function, there is a parameter which the designer can regulate for specified objectives. A sliding-mode controller is synthesized to ensure the reachability of the specified switching surface, despite actuator degradation and uncertainties. Finally, the simulation results demonstrate the effectiveness of the proposed method.

  6. Estimation of the shear force in transverse dynamic force microscopy using a sliding mode observer

    NASA Astrophysics Data System (ADS)

    Nguyen, Thang; Hatano, Toshiaki; Khan, Said G.; Zhang, Kaiqiang; Edwards, Christopher; Harniman, Robert; Burgess, Stuart C.; Antognozzi, Massimo; Miles, Mervyn; Herrmann, Guido

    2015-09-01

    In this paper, the problem of estimating the shear force affecting the tip of the cantilever in a Transverse Dynamic Force Microscope (TDFM) using a real-time implementable sliding mode observer is addressed. The behaviour of a vertically oriented oscillated cantilever, in close proximity to a specimen surface, facilitates the imaging of the specimen at nano-metre scale. Distance changes between the cantilever tip and the specimen can be inferred from the oscillation amplitudes, but also from the shear force acting at the tip. Thus, the problem of accurately estimating the shear force is of significance when specimen images and mechanical properties need to be obtained at submolecular precision. A low order dynamic model of the cantilever is derived using the method of lines, for the purpose of estimating the shear force. Based on this model, an estimator using sliding mode techniques is presented to reconstruct the unknown shear force, from only tip position measurements and knowledge of the excitation signal applied to the top of the cantilever. Comparisons to methods assuming a quasi-static harmonic balance are made.

  7. Fault-Tolerant Control of Wind Turbines using a Takagi-Sugeno Sliding Mode Observer

    NASA Astrophysics Data System (ADS)

    Georg, Sören; Schulte, Horst

    2014-06-01

    In this paper, observer-based fault-tolerant control schemes for actuator and sensor faults are implemented within dynamic wind turbine simulations. The faults are directly reconstructed by means of a Takagi-Sugeno sliding mode observer. As simulation models, both a reduced-order model with 4 degrees of freedom and the aero-elastic code FAST by NREL are used. A fault-tolerant control scheme is set up by subtracting the reconstructed fault from the faulty control signal respectively sensor value. With these fault compensation schemes, the corrected controller behaviour is close to the fault-free case. The global stability of the controller in the full-load region in the presence of faults and with active fault compensation is shown by analysing the derivative of an appropriate Lyapunov function.

  8. A novel discrete adaptive sliding-mode-like control method for ionic polymer-metal composite manipulators

    NASA Astrophysics Data System (ADS)

    Sun, Zhiyong; Hao, Lina; Chen, Wenlin; Li, Zhi; Liu, Liqun

    2013-09-01

    Ionic polymer-metal composite (IPMC), also called artificial muscle, is an EAP material which can generate a relatively large deformation with a low driving voltage (generally less than 5 V). Like other EAP materials, IPMC possesses strong nonlinear properties, which can be described as a hybrid of back-relaxation (BR) and hysteresis characteristics, which also vary with water content, environmental temperature and even the usage consumption. Nowadays, many control approaches have been developed to tune the IPMC actuators, among which adaptive methods show a particular striking performance. To deal with IPMCs’ nonlinear problem, this paper represents a robust discrete adaptive inverse (AI) control approach, which employs an on-line identification technique based on the BR operator and Prandtl-Ishlinskii (PI) hysteresis operator hybrid model estimation method. Here the newly formed control approach is called discrete adaptive sliding-mode-like control (DASMLC) due to the similarity of its design method to that of a sliding mode controller. The weighted least mean squares (WLMS) identification method was employed to estimate the hybrid IPMC model because of its advantage of insensitivity to environmental noise. Experiments with the DASMLC approach and a conventional PID controller were carried out to compare and demonstrate the proposed controller’s better performance.

  9. Ensemble transform sensitivity method for adaptive observations

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Xie, Yuanfu; Wang, Hongli; Chen, Dehui; Toth, Zoltan

    2016-01-01

    The Ensemble Transform (ET) method has been shown to be useful in providing guidance for adaptive observation deployment. It predicts forecast error variance reduction for each possible deployment using its corresponding transformation matrix in an ensemble subspace. In this paper, a new ET-based sensitivity (ETS) method, which calculates the gradient of forecast error variance reduction in terms of analysis error variance reduction, is proposed to specify regions for possible adaptive observations. ETS is a first order approximation of the ET; it requires just one calculation of a transformation matrix, increasing computational efficiency (60%-80% reduction in computational cost). An explicit mathematical formulation of the ETS gradient is derived and described. Both the ET and ETS methods are applied to the Hurricane Irene (2011) case and a heavy rainfall case for comparison. The numerical results imply that the sensitive areas estimated by the ETS and ET are similar. However, ETS is much more efficient, particularly when the resolution is higher and the number of ensemble members is larger.

  10. Flexible Modes Control Using Sliding Mode Observers: Application to Ares I

    NASA Technical Reports Server (NTRS)

    Shtessel, Yuri B.; Hall, Charles E.; Baev, Simon; Orr, Jeb S.

    2010-01-01

    The launch vehicle dynamics affected by bending and sloshing modes are considered. Attitude measurement data that are corrupted by flexible modes could yield instability of the vehicle dynamics. Flexible body and sloshing modes are reconstructed by sliding mode observers. The resultant estimates are used to remove the undesirable dynamics from the measurements, and the direct effects of sloshing and bending modes on the launch vehicle are compensated by means of a controller that is designed without taking the bending and sloshing modes into account. A linearized mathematical model of Ares I launch vehicle was derived based on FRACTAL, a linear model developed by NASA/MSFC. The compensated vehicle dynamics with a simple PID controller were studied for the launch vehicle model that included two bending modes, two slosh modes and actuator dynamics. A simulation study demonstrated stable and accurate performance of the flight control system with the augmented simple PID controller without the use of traditional linear bending filters.

  11. Adaptive backstepping sliding mode control of flexible ball screw drives with time-varying parametric uncertainties and disturbances.

    PubMed

    Dong, Liang; Tang, Wen Cheng

    2014-01-01

    This paper presents a method to model and design servo controllers for flexible ball screw drives with dynamic variations. A mathematical model describing the structural flexibility of the ball screw drive containing time-varying uncertainties and disturbances with unknown bounds is proposed. A mode-compensating adaptive backstepping sliding mode controller is designed to suppress the vibration. The time-varying uncertainties and disturbances represented in finite-term Fourier series can be estimated by updating the Fourier coefficients through function approximation technique. Adaptive laws are obtained from Lyapunov approach to guarantee the convergence and stability of the closed loop system. The simulation results indicate that the tracking accuracy is improved considerably with the proposed scheme when the time-varying parametric uncertainties and disturbances exist.

  12. Design and Experimental Evaluation of a Robust Position Controller for an Electrohydrostatic Actuator Using Adaptive Antiwindup Sliding Mode Scheme

    PubMed Central

    Lee, Ji Min; Park, Sung Hwan; Kim, Jong Shik

    2013-01-01

    A robust control scheme is proposed for the position control of the electrohydrostatic actuator (EHA) when considering hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities. To reduce overshoot due to a saturation of electric motor and to realize robustness against load disturbance and lumped system uncertainties such as varying parameters and modeling error, this paper proposes an adaptive antiwindup PID sliding mode scheme as a robust position controller for the EHA system. An optimal PID controller and an optimal anti-windup PID controller are also designed to compare control performance. An EHA prototype is developed, carrying out system modeling and parameter identification in designing the position controller. The simply identified linear model serves as the basis for the design of the position controllers, while the robustness of the control systems is compared by experiments. The adaptive anti-windup PID sliding mode controller has been found to have the desired performance and become robust against hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities. PMID:23983640

  13. Design and experimental evaluation of a robust position controller for an electrohydrostatic actuator using adaptive antiwindup sliding mode scheme.

    PubMed

    Lee, Ji Min; Park, Sung Hwan; Kim, Jong Shik

    2013-01-01

    A robust control scheme is proposed for the position control of the electrohydrostatic actuator (EHA) when considering hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities. To reduce overshoot due to a saturation of electric motor and to realize robustness against load disturbance and lumped system uncertainties such as varying parameters and modeling error, this paper proposes an adaptive antiwindup PID sliding mode scheme as a robust position controller for the EHA system. An optimal PID controller and an optimal anti-windup PID controller are also designed to compare control performance. An EHA prototype is developed, carrying out system modeling and parameter identification in designing the position controller. The simply identified linear model serves as the basis for the design of the position controllers, while the robustness of the control systems is compared by experiments. The adaptive anti-windup PID sliding mode controller has been found to have the desired performance and become robust against hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities.

  14. Adhesion and sliding response of a biologically inspired fibrillar surface: experimental observations.

    PubMed

    Yao, H; Rocca, G Della; Guduru, P R; Gao, H

    2008-07-01

    Inspired by the adhesion mechanisms of several animal species such as geckos, beetles and flies, several efforts in designing and fabricating surface engineering strategies have been made recently to mimic the adhesive and frictional behaviour of biological foot pads. An important feature of such biological adhesion systems is the ability to switch between strong attachment and easy detachment, which is crucial for animal locomotion. Recent investigations have suggested that such a 'switching' mechanism can be achieved by the elastic anisotropy of the attachment pad, which renders the magnitude of the detachment force to be direction dependent. This suggestion is supported by the observations that the fibres of the foot pads in geckos and insects are oriented at an angle to the base and that geckos curl their toes backwards (digital hyperextension) while detaching from a surface. One of the promising bio-inspired architectures developed recently is a film-terminated fibrillar PDMS surface; this structure was demonstrated to result in superior detachment force and energy dissipation compared with a bulk PDMS surface. In this investigation, the film-terminated fibrillar architecture is modified by tilting the fibres to make the surface vertically more compliant and elastically anisotropic. The directional detachment and the sliding resistance between the tilted fibrillar surfaces and a spherical glass lens are measured: both show significant directional anisotropy. It is argued that the anisotropy introduced by the tilted fibres and the deformation-induced change in the compliance of the fibre layer are responsible for the observed anisotropy in the detachment force.

  15. Cold start dynamics and temperature sliding observer design of an automotive SOFC APU

    NASA Astrophysics Data System (ADS)

    Lin, Po-Hsu; Hong, Che-Wun

    This paper presents a dynamic model for studying the cold start dynamics and observer design of an auxiliary power unit (APU) for automotive applications. The APU is embedded with a solid oxide fuel cell (SOFC) stack which is a quiet and pollutant-free electric generator; however, it suffers from slow start problem from ambient conditions. The SOFC APU system equips with an after-burner to accelerate the start-up transient in this research. The combustion chamber burns the residual fuel (and air) left from the SOFC to raise the exhaust temperature to preheat the SOFC stack through an energy recovery unit. Since thermal effect is the dominant factor that influences the SOFC transient and steady performance, a nonlinear real-time sliding observer for stack temperature was implemented into the system dynamics to monitor the temperature variation for future controller design. The simulation results show that a 100 W APU system in this research takes about 2 min (in theory) for start-up without considering the thermal limitation of the cell fracture.

  16. State observer-based sliding mode control for semi-active hydro-pneumatic suspension

    NASA Astrophysics Data System (ADS)

    Ren, Hongbin; Chen, Sizhong; Zhao, Yuzhuang; Liu, Gang; Yang, Lin

    2016-02-01

    This paper proposes an improved virtual reference model for semi-active suspension to coordinate the vehicle ride comfort and handling stability. The reference model combines the virtues of sky-hook with ground-hook control logic, and the hybrid coefficient is tuned according to the longitudinal and lateral acceleration so as to improve the vehicle stability especially in high-speed condition. Suspension state observer based on unscented Kalman filter is designed. A sliding mode controller (SMC) is developed to track the states of the reference model. The stability of the SMC strategy is proven by means of Lyapunov function taking into account the nonlinear damper characteristics and sprung mass variation of the vehicle. Finally, the performance of the controller is demonstrated under three typical working conditions: the random road excitation, speed bump road and sharp acceleration and braking. The simulation results indicated that, compared with the traditional passive suspension, the proposed control algorithm can offer a better coordination between vehicle ride comfort and handling stability. This approach provides a viable alternative to costlier active suspension control systems for commercial vehicles.

  17. A sliding-mode-based observer to identify faults in FBG sensors embedded in composite structures

    NASA Astrophysics Data System (ADS)

    Cazzulani, Gabriele; Cinquemani, Simone; Ronchi, Marco

    2016-04-01

    Optical strain gauges, such as Fiber Bragg Gratings (FBG), have a great potential for smart structures, thanks to their small transversal size and the possibility to make an array of many sensors. They can be embedded in composite structures and their effect on the structure is nearly negligible. These advantages make them very interesting in the field of active vibration suppression. Unfortunately their low reliability is an obstacle to their use in such applications. For this reason, this paper introduces a fault identification algorithm to identify online those sensors which are not working correctly. The algorithm is based on the use of a sliding mode observer to estimate the coherence of measurements, and then to highlight possible faults. Once identified, the corresponding sensors can be excluded from the feedback loop of the control algorithm to avoid unwanted behaviors or instabilities. Numerical and experimental tests have been carried out on a carbon fiber structure considering different fault conditions. Results show it is possible to identify the faulty sensors and thus improve the signals used in the feedback loop.

  18. Active Pneumatic Vibration Control by Using Pressure and Velocity Measurements and Adaptive Fuzzy Sliding-Mode Controller

    PubMed Central

    Chen, Hung-Yi; Liang, Jin-Wei; Wu, Jia-Wei

    2013-01-01

    This paper presents an intelligent control strategy to overcome nonlinear and time-varying characteristics of a diaphragm-type pneumatic vibration isolator (PVI) system. By combining an adaptive rule with fuzzy and sliding-mode control, the method has online learning ability when it faces the system's nonlinear and time-varying behaviors during an active vibration control process. Since the proposed scheme has a simple structure, it is easy to implement. To validate the proposed scheme, a composite control which adopts both chamber pressure and payload velocity as feedback signal is implemented. During experimental investigations, sinusoidal excitation at resonance and random-like signal are input on a floor base to simulate ground vibration. Performances obtained from the proposed scheme are compared with those obtained from passive system and PID scheme to illustrate the effectiveness of the proposed intelligent control. PMID:23820746

  19. Designing adaptive integral sliding mode control for heart rate regulation during cycle-ergometer exercise using bio-feedback.

    PubMed

    Argha, Ahmadreza; Su, Steven W; Nguyen, Hung; Celler, Branko G

    2015-01-01

    This paper considers our developed control system which aims to regulate the exercising subjects' heart rate (HR) to a predefined profile. The controller would be an adaptive integral sliding mode controller. Here it is assumed that the controller commands are interpreted as biofeedback auditory commands. These commands can be heard and implemented by the exercising subject as a part of the control-loop. However, transmitting a feedback signal while the pedals are not in the appropriate position to efficiently exert force may lead to a cognitive disengagement of the user from the feedback controller. To address this problem this paper will employ a different form of control system regarding as "actuator-based event-driven control system". This paper will claim that the developed event-driven controller makes it possible to effectively regulate HR to a predetermined HR profile.

  20. An experimental comparison of proportional-integral, sliding mode, and robust adaptive control for piezo-actuated nanopositioning stages.

    PubMed

    Gu, Guo-Ying; Zhu, Li-Min

    2014-05-01

    This paper presents a comparative study of the proportional-integral (PI) control, sliding mode control (SMC), and robust adaptive control (RAC) for applications to piezo-actuated nanopositioning stages without the inverse hysteresis construction. For a fair comparison, the control parameters of the SMC and RAC are selected on the basis of the well-tuned parameters of the PI controller under same desired trajectories and sampling frequencies. The comparative results show that the RAC improves the tracking performance by 17 and 37 times than the PI controller in terms of the maximum tracking error e(m) and the root mean tracking error e(rms), respectively, while the RAC improves the tracking performance by 7 and 9 times than the SMC in terms of e(m) and e(rms), respectively.

  1. Adhesion and sliding response of a biologically inspired fibrillar surface: experimental observations.

    PubMed

    Yao, H; Rocca, G Della; Guduru, P R; Gao, H

    2008-07-01

    Inspired by the adhesion mechanisms of several animal species such as geckos, beetles and flies, several efforts in designing and fabricating surface engineering strategies have been made recently to mimic the adhesive and frictional behaviour of biological foot pads. An important feature of such biological adhesion systems is the ability to switch between strong attachment and easy detachment, which is crucial for animal locomotion. Recent investigations have suggested that such a 'switching' mechanism can be achieved by the elastic anisotropy of the attachment pad, which renders the magnitude of the detachment force to be direction dependent. This suggestion is supported by the observations that the fibres of the foot pads in geckos and insects are oriented at an angle to the base and that geckos curl their toes backwards (digital hyperextension) while detaching from a surface. One of the promising bio-inspired architectures developed recently is a film-terminated fibrillar PDMS surface; this structure was demonstrated to result in superior detachment force and energy dissipation compared with a bulk PDMS surface. In this investigation, the film-terminated fibrillar architecture is modified by tilting the fibres to make the surface vertically more compliant and elastically anisotropic. The directional detachment and the sliding resistance between the tilted fibrillar surfaces and a spherical glass lens are measured: both show significant directional anisotropy. It is argued that the anisotropy introduced by the tilted fibres and the deformation-induced change in the compliance of the fibre layer are responsible for the observed anisotropy in the detachment force. PMID:17971321

  2. Design of an adaptive fuzzy sliding mode control for uncertain discrete-time nonlinear systems based on noisy measurements

    NASA Astrophysics Data System (ADS)

    Yoshimura, Toshio

    2016-02-01

    This paper presents the design of an adaptive fuzzy sliding mode control (AFSMC) for uncertain discrete-time nonlinear dynamic systems. The dynamic systems are described by a discrete-time state equation with nonlinear uncertainties, and the uncertainties include the modelling errors and the external disturbances to be unknown but nonlinear with the bounded properties. The states are measured by the restriction of measurement sensors and the contamination with independent measurement noises. The nonlinear uncertainties are approximated by using the fuzzy IF-THEN rules based on the universal approximation theorem, and the approximation error is compensated by adding an adaptive complementary term to the proposed AFSMC. The fuzzy inference approach based on the extended single input rule modules is proposed to reduce the number of the fuzzy IF-THEN rules. The estimates for the un-measurable states and the adjustable parameters are obtained by using the weighted least squares estimator and its simplified one. It is proved that under some conditions the estimation errors will remain in the vicinity of zero as time increases, and the states are ultimately bounded subject to the proposed AFSMC. The effectiveness of the proposed method is indicated through the simulation experiment of a simple numerical system.

  3. The adaptive observer. [liapunov synthesis, single-input single-output, and reduced observers

    NASA Technical Reports Server (NTRS)

    Carroll, R. L.

    1973-01-01

    The simple generation of state from available measurements, for use in systems for which the criteria defining the acceptable state behavior mandates a control that is dependent upon unavailable measurement is described as an adaptive means for determining the state of a linear time invariant differential system having unknown parameters. A single input output adaptive observer and the reduced adaptive observer is developed. The basic ideas for both the adaptive observer and the nonadaptive observer are examined. A survey of the Liapunov synthesis technique is taken, and the technique is applied to adaptive algorithm for the adaptive observer.

  4. A new fractional-order sliding mode controller via a nonlinear disturbance observer for a class of dynamical systems with mismatched disturbances.

    PubMed

    Pashaei, Shabnam; Badamchizadeh, Mohammadali

    2016-07-01

    This paper investigates the stabilization and disturbance rejection for a class of fractional-order nonlinear dynamical systems with mismatched disturbances. To fulfill this purpose a new fractional-order sliding mode control (FOSMC) based on a nonlinear disturbance observer is proposed. In order to design the suitable fractional-order sliding mode controller, a proper switching surface is introduced. Afterward, by using the sliding mode theory and Lyapunov stability theory, a robust fractional-order control law via a nonlinear disturbance observer is proposed to assure the existence of the sliding motion in finite time. The proposed fractional-order sliding mode controller exposes better control performance, ensures fast and robust stability of the closed-loop system, eliminates the disturbances and diminishes the chattering problem. Finally, the effectiveness of the proposed fractional-order controller is depicted via numerical simulation results of practical example and is compared with some other controllers.

  5. Synchronization analysis and control of three eccentric rotors in a vibrating system using adaptive sliding mode control algorithm

    NASA Astrophysics Data System (ADS)

    Kong, Xiangxi; Zhang, Xueliang; Chen, Xiaozhe; Wen, Bangchun; Wang, Bo

    2016-05-01

    In this paper, self- and controlled synchronizations of three eccentric rotors (ERs) in line driven by induction motors rotating in the same direction in a vibrating system are investigated. The vibrating system is a typical underactuated mechanical-electromagnetic coupling system. The analysis and control of the vibrating system convert to the synchronization motion problem of three ERs. Firstly, the self-synchronization motion of three ERs is analyzed according to self-synchronization theory. The criterions of synchronization and stability of self-synchronous state are obtained by using a modified average perturbation method. The significant synchronization motion of three ERs with zero phase differences cannot be implemented according to self-synchronization theory through analysis and simulations. To implement the synchronization motion of three ERs with zero phase differences, an adaptive sliding mode control (ASMC) algorithm based on a modified master-slave control strategy is employed to design the controllers. The stability of the controllers is verified by using Lyapunov theorem. The performances of the controlled synchronization system are presented by simulations to demonstrate the effectiveness of controllers. Finally, the effects of reference speed and non-zero phase differences on the controlled system are discussed to show the strong robustness of the proposed controllers. Additionally, the dynamic responses of the vibrating system in different synchronous states are analyzed.

  6. Tendon glycosaminoglycan proteoglycan sidechains promote collagen fibril sliding-AFM observations at the nanoscale.

    PubMed

    Rigozzi, S; Müller, R; Stemmer, A; Snedeker, J G

    2013-02-22

    The extracellular matrix of tendon is mainly composed of discontinuous Type-I collagen fibrils and small leucine rich proteoglycans (PG). Macroscopic tendon behaviors like stiffness and strength are determined by the ultrastructural arrangement of these components. When a tendon is submitted to load, the collagen fibrils both elongate and slide relative to their neighboring fibrils. The role of PG glycosaminoglycan (GAG) sidechains in mediating inter-fibril load sharing remains controversial, with competing structure-function theories suggesting that PGs may mechanically couple neighboring collagen fibrils (cross-linking them to facilitate fibril stretch) or alternatively isolating them (promoting fibril gliding). In this study, we sought to clarify the functional role of GAGs in tensile tendon mechanics by directly investigating the mechanical response of individual collagen fibrils within their collagen network in both native and GAG depleted tendons. A control group of Achilles tendons from adult mice was compared with tendons in which GAGs were enzymatically depleted using chondroitinase ABC. Tendons were loaded to specific target strains, chemically fixed under constant load, and later sectioned for morphological analysis by an atomic force microscope (AFM). Increases in periodic banding of the collagen fibrils (D-period) or decreases in fibril diameter was considered to be representative of collagen fibril elongation and the mechanical contribution of GAGs at the ultrascale was quantified on this basis. At high levels of applied tendon strain (10%), GAG depleted tendons showed increased collagen stretch (less fibril sliding). We conclude that the hydrophilic GAGs seem thus not to act as mechanical crosslinks but rather act to promote collagen fibril sliding under tension.

  7. Observations of grain-boundary sliding and surface topography in an 8090 Al alloy after uniaxial and biaxial superplastic deformation

    SciTech Connect

    Chen, T.R.; Huang, J.C.

    1999-01-01

    The surface topography of an 8090 aluminum alloy was studied after uniaxial or biaxial superplastic deformation, with particular reference to grain-boundary sliding (GBS) offsets, grain rotation angles, formation of striated bands (SBs) or fibers, cavity distribution, and cavity formation mechanisms. Additionally, the contribution of GBS or grain separation to the overall strain was evaluated. Striated bands were observed and are thought to be the newly exposed faces of the grains inclined to the specimen`s surface. They were formed by sliding of grains upward and downward relative to the specimen surface. Grooves and crests inside SBs were formed from the relative motion of grain-boundary defects. Fibers were observed and are thought to be the further development of the SBs resulting from the formation of elongated cavities and grain separation. More cavitation was found in equibiaxially strained regions than in other regions subjected to approximately equivalent levels of strain. About 50 pct of the total strain was contributed to GBS in the uniaxial tensile-loaded specimens, as compared to about 30 pct in the biaxial-strained specimens. The effects of grain separation, grain rotation, and secondary GBS may be the reasons for the reduction of the observed strain contribution from GBS in biaxially strained specimens.

  8. Comparability of naturalistic and controlled observation assessment of adaptive behavior.

    PubMed

    Millham, J; Chilcutt, J; Atkinson, B L

    1978-07-01

    The comparability of retrospective naturalistic and controlled observation assessment of adaptive behavior was evaluated. The number, degree, and direction of discrepancies were evaluated with respect to level of retardation of the client, rater differences, behavior domain sampled, and prior observational base for the ratings. Generally poor comparability between the procedures was found and questions were raised concerning the types of generalizability that can be made from adaptive behavior assessment obtained under the two procedures.

  9. Emplacement mechanisms of the South Kona slide complex, Hawaii Island: Sampling and observations by remotely operated vehicle Kaiko

    USGS Publications Warehouse

    Yokose, H.; Lipman, P.W.

    2004-01-01

    Emplacement of a giant submarine slide complex, offshore of South Kona, Hawaii Island, was investigated in 2001 by visual observation and in-situ sampling on the bench scarp and a megablock, during two dives utilizing the Remotely Operated Vehicle (ROV) Kaiko and its mother ship R/V Kairei. Topography of the bench scarp and megablocks were defined in 3-D perspective, using high-resolution digital bathymetric data acquired during the cruise. Compositions of 34 rock samples provide constraints on the landslide source regions and emplacement mechanisms. The bench scarp consists mainly of highly fractured, vesiculated, and oxidized a-a lavas that slumped from the subaerial flank of ancestral Mauna Loa. The megablock contains three units: block facies, matrix facies, and draped sediment. The block facies contains hyaloclastite interbedded with massive lava, which slid from the shallow submarine flank of ancestral Mauna Loa, as indicated by glassy groundmass of the hyaloclastite, low oxidation state, and low sulfur content. The matrix facies, which directly overlies the block facies and is similar to a lahar deposit, is thought to have been deposited from the water column immediately after the South Kona slide event. The draped sediment is a thin high-density turbidite layer that may be a distal facies of the Alika-2 debris-avalanche deposit; its composition overlaps with rocks from subaerial Mauna Loa. The deposits generated by the South Kona slide vary from debris avalanche deposit to turbidite. Spatial distribution of the deposits is consistent with deposits related to large landslides adjacent to other Hawaiian volcanoes and the Canary Islands. ?? Springer-Verlag 2004.

  10. Tracking with asymptotic sliding mode and adaptive input delay effect compensation of nonlinearly perturbed delayed systems applied to traffic feedback control

    NASA Astrophysics Data System (ADS)

    Mirkin, Boris; Haddad, Jack; Shtessel, Yuri

    2016-09-01

    Asymptotical sliding mode-model reference adaptive control design for a class of systems with parametric uncertainty, unknown nonlinear perturbation and external disturbance, and with known input and state delays is proposed. To overcome the difficulty to directly predict the plant state under uncertainties, a control design is based on a developed decomposition procedure, where a 'generalised error' in conjunction with auxiliary linear dynamic blocks with adjustable gains is introduced and the sliding variable is formed on the basis of this error. The effect of such a decomposition is to pull the input delay out of first step of the design procedure. As a result, similarly to the classical Smith predictor, the adaptive control architecture based only on the lumped-delays, i.e. without conventional in such cases difficult-implemented distributed-delay blocks. Two new adaptive control schemes are proposed. A linearisation-based control design is constructed for feedback control of an urban traffic region model with uncertain dynamics. Simulation results demonstrate the effectiveness of the developed adaptive control method.

  11. Observation and output adaptive tracking for a class of nonlinear non-minimum phase systems

    NASA Astrophysics Data System (ADS)

    Bartolini, G.; Estrada, A.; Punta, E.

    2016-09-01

    In this paper, the output tracking problem for a class of systems with unstable zero dynamics is addressed. The state is assumed not measurable. The output of the dynamical system to be controlled has to track a signal, which is the sum of a known number of sinusoids with unknown frequencies, amplitudes and phases. The non-minimum phase nature of the considered systems prevents the direct tracking by standard sliding mode methods, which are known to generate unstable behaviours of the internal dynamics. The proposed method relies on the availability of a flat output and its time derivatives which are functions of the unavailable state; therefore, a nonlinear observer is needed. Due to the uncertainty in the frequencies and in the parameters defining the relationship between the output of the system and the flat states, adaptive indirect methods are applied.

  12. Observer-based robust finite time H∞ sliding mode control for Markovian switching systems with mode-dependent time-varying delay and incomplete transition rate.

    PubMed

    Gao, Lijun; Jiang, Xiaoxiao; Wang, Dandan

    2016-03-01

    This paper investigates the problem of robust finite time H∞ sliding mode control for a class of Markovian switching systems. The system is subjected to the mode-dependent time-varying delay, partly unknown transition rate and unmeasurable state. The main difficulty is that, a sliding mode surface cannot be designed based on the unknown transition rate and unmeasurable state directly. To overcome this obstacle, the set of modes is firstly divided into two subsets standing for known transition rate subset and unknown one, based on which a state observer is established. A component robust finite-time sliding mode controller is also designed to cope with the effect of partially unknown transition rate. It is illustrated that the reachability, finite-time stability, finite-time boundedness, finite-time H∞ state feedback stabilization of sliding mode dynamics can be ensured despite the unknown transition rate. Finally, the simulation results verify the effectiveness of robust finite time control problem.

  13. Online Fault Detection of Permanent Magnet Demagnetization for IPMSMs by Nonsingular Fast Terminal-Sliding-Mode Observer

    PubMed Central

    Zhao, Kai-Hui; Chen, Te-Fang; Zhang, Chang-Fan; He, Jing; Huang, Gang

    2014-01-01

    To prevent irreversible demagnetization of a permanent magnet (PM) for interior permanent magnet synchronous motors (IPMSMs) by flux-weakening control, a robust PM flux-linkage nonsingular fast terminal-sliding-mode observer (NFTSMO) is proposed to detect demagnetization faults. First, the IPMSM mathematical model of demagnetization is presented. Second, the construction of the NFTSMO to estimate PM demagnetization faults in IPMSM is described, and a proof of observer stability is given. The fault decision criteria and fault-processing method are also presented. Finally, the proposed scheme was simulated using MATLAB/Simulink and implemented on the RT-LAB platform. A number of robustness tests have been carried out. The scheme shows good performance in spite of speed fluctuations, torque ripples and the uncertainties of stator resistance. PMID:25490582

  14. Robust Sensor Faults Reconstruction for a Class of Uncertain Linear Systems Using a Sliding Mode Observer: An LMI Approach

    NASA Astrophysics Data System (ADS)

    Iskander, Boulaabi; Anis, Sellami; Fayçal, Ben Hmida; Moncef, Gossa

    2009-03-01

    This paper presents a design method of a Sliding Mode Observer (SMO) for robust sensor faults reconstruction of systems with matched uncertainty. This class of uncertainty requires a known upper bound. The basic idea is to use the H∞ concept to design the observer, which minimizes the effect of the uncertainty on the reconstruction of the sensor faults. Specifically, we applied the equivalent output error injection concept from previous work in Fault Detection and Isolation (FDI) scheme. Then, these two problems of design and reconstruction can be expressed and numerically formulate via Linear Matrix Inequalities (LMIs) optimization. Finally, a numerical example is given to illustrate the validity and the applicability of the proposed approach.

  15. Robust Sensor Faults Reconstruction for a Class of Uncertain Linear Systems Using a Sliding Mode Observer: An LMI Approach

    SciTech Connect

    Iskander, Boulaabi; Faycal, Ben Hmida; Moncef, Gossa; Anis, Sellami

    2009-03-05

    This paper presents a design method of a Sliding Mode Observer (SMO) for robust sensor faults reconstruction of systems with matched uncertainty. This class of uncertainty requires a known upper bound. The basic idea is to use the H{sub {infinity}} concept to design the observer, which minimizes the effect of the uncertainty on the reconstruction of the sensor faults. Specifically, we applied the equivalent output error injection concept from previous work in Fault Detection and Isolation (FDI) scheme. Then, these two problems of design and reconstruction can be expressed and numerically formulate via Linear Matrix Inequalities (LMIs) optimization. Finally, a numerical example is given to illustrate the validity and the applicability of the proposed approach.

  16. Online fault detection of permanent magnet demagnetization for IPMSMs by nonsingular fast terminal-sliding-mode observer.

    PubMed

    Zhao, Kai-Hui; Chen, Te-Fang; Zhang, Chang-Fan; He, Jing; Huang, Gang

    2014-12-05

    To prevent irreversible demagnetization of a permanent magnet (PM) for interior permanent magnet synchronous motors (IPMSMs) by flux-weakening control, a robust PM flux-linkage nonsingular fast terminal-sliding-mode observer (NFTSMO) is proposed to detect demagnetization faults. First, the IPMSM mathematical model of demagnetization is presented. Second, the construction of the NFTSMO to estimate PM demagnetization faults in IPMSM is described, and a proof of observer stability is given. The fault decision criteria and fault-processing method are also presented. Finally, the proposed scheme was simulated using MATLAB/Simulink and implemented on the RT-LAB platform. A number of robustness tests have been carried out. The scheme shows good performance in spite of speed fluctuations, torque ripples and the uncertainties of stator resistance.

  17. Repeated observation of an uncertain signal. [sensory adaptation

    NASA Technical Reports Server (NTRS)

    Swets, J. A.; Birdsall, T. G.

    1978-01-01

    The focus here is on sensory adaptation, or progressively more appropriate attention, as repeated observations yield more information about a signal with an uncertain parameter. The signal was a brief sinusoid; its uncertain parameter was frequency. Detection performance is predicted from data on a signal of known and constant frequency, as a function of the number of frequencies the uncertain signal could assume. A comparison condition presented a signal that varied in a manner not permitting adaptation. Models derived from signal detection theory describe the ideal observation processes for the three signal conditions, and supply quantitative predictions of relative performances. The models are generally supported by the data.

  18. Decentralized Sliding Mode Observer Based Dual Closed-Loop Fault Tolerant Control for Reconfigurable Manipulator against Actuator Failure

    PubMed Central

    Zhao, Bo; Li, Yuanchun

    2015-01-01

    This paper considers a decentralized fault tolerant control (DFTC) scheme for reconfigurable manipulators. With the appearance of norm-bounded failure, a dual closed-loop trajectory tracking control algorithm is proposed on the basis of the Lyapunov stability theory. Characterized by the modularization property, the actuator failure is estimated by the proposed decentralized sliding mode observer (DSMO). Moreover, the actuator failure can be treated in view of the local joint information, so its control performance degradation is independent of other normal joints. In addition, the presented DFTC scheme is significantly simplified in terms of the structure of the controller due to its dual closed-loop architecture, and its feasibility is highly reflected in the control of reconfigurable manipulators. Finally, the effectiveness of the proposed DFTC scheme is demonstrated using simulations. PMID:26181826

  19. Decentralized Sliding Mode Observer Based Dual Closed-Loop Fault Tolerant Control for Reconfigurable Manipulator against Actuator Failure.

    PubMed

    Zhao, Bo; Li, Chenghao; Liu, Derong; Li, Yuanchun

    2015-01-01

    This paper considers a decentralized fault tolerant control (DFTC) scheme for reconfigurable manipulators. With the appearance of norm-bounded failure, a dual closed-loop trajectory tracking control algorithm is proposed on the basis of the Lyapunov stability theory. Characterized by the modularization property, the actuator failure is estimated by the proposed decentralized sliding mode observer (DSMO). Moreover, the actuator failure can be treated in view of the local joint information, so its control performance degradation is independent of other normal joints. In addition, the presented DFTC scheme is significantly simplified in terms of the structure of the controller due to its dual closed-loop architecture, and its feasibility is highly reflected in the control of reconfigurable manipulators. Finally, the effectiveness of the proposed DFTC scheme is demonstrated using simulations. PMID:26181826

  20. Decentralized Sliding Mode Observer Based Dual Closed-Loop Fault Tolerant Control for Reconfigurable Manipulator against Actuator Failure.

    PubMed

    Zhao, Bo; Li, Chenghao; Liu, Derong; Li, Yuanchun

    2015-01-01

    This paper considers a decentralized fault tolerant control (DFTC) scheme for reconfigurable manipulators. With the appearance of norm-bounded failure, a dual closed-loop trajectory tracking control algorithm is proposed on the basis of the Lyapunov stability theory. Characterized by the modularization property, the actuator failure is estimated by the proposed decentralized sliding mode observer (DSMO). Moreover, the actuator failure can be treated in view of the local joint information, so its control performance degradation is independent of other normal joints. In addition, the presented DFTC scheme is significantly simplified in terms of the structure of the controller due to its dual closed-loop architecture, and its feasibility is highly reflected in the control of reconfigurable manipulators. Finally, the effectiveness of the proposed DFTC scheme is demonstrated using simulations.

  1. 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

  2. An Adaptive Buddy Check for Observational Quality Control

    NASA Technical Reports Server (NTRS)

    Dee, Dick P.; Rukhovets, Leonid; Todling, Ricardo; DaSilva, Arlindo M.; Larson, Jay W.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    An adaptive buddy check algorithm is presented that adjusts tolerances for outlier observations based on the variability of surrounding data. The algorithm derives from a statistical hypothesis test combined with maximum-likelihood covariance estimation. Its stability is shown to depend on the initial identification of outliers by a simple background check. The adaptive feature ensures that the final quality control decisions are not very sensitive to prescribed statistics of first-guess and observation errors, nor on other approximations introduced into the algorithm. The implementation of the algorithm in a global atmospheric data assimilation is described. Its performance is contrasted with that of a non-adaptive buddy check, for the surface analysis of an extreme storm that took place in Europe on 27 December 1999. The adaptive algorithm allowed the inclusion of many important observations that differed greatly from the first guess and that would have been excluded on the basis of prescribed statistics. The analysis of the storm development was much improved as a result of these additional observations.

  3. Physics in water slides

    NASA Astrophysics Data System (ADS)

    Thomazo, Jean-Baptiste; Reyssat, Etienne; Fermigier, Marc

    2015-11-01

    Water slides are body-size inclined pipes fed with water to improve sliding. Water is allowed to freely flow down the slide. It forms a lubrication film that reduces friction between the slide and the body, allowing sliders to travel down at high speeds. We present the results of an experimental study on a model water slide at the scale of the laboratory. We analyze the sliding velocities of cylindrical objects of various masses and sizes sliding down an inclined gutter fed with a controlled flux of water. In the range of parameters that we have studied, we show that the speed of the model sliders is faster than the flow of the environing water. We propose a minimal model to account for the observed sliding velocities measured in our experiments. The sliding velocity is set by a balance of the apparent weight with inertial drag or viscous friction in the lubrication film under the slider. Other resisting mechanisms will also be discussed.

  4. Neptune and Titan Observed with Keck Telescope Adaptive Optics

    SciTech Connect

    Max, C.E.; Macintosh, B.A.; Gibbard, S.; Gavel, D.T.; Roe, H.; De Pater, I.; Ghez, A.M.; Acton, S.; Wizinowich, P.L.; Lai, O.

    2000-05-05

    The authors report on observations taken during engineering science validation time using the new adaptive optics system at the 10-m Keck II Telescope. They observe Neptune and Titan at near-infrared wavelengths. These objects are ideal for adaptive optics imaging because they are bright and small, yet have many diffraction-limited resolution elements across their disks. In addition Neptune and Titan have prominent physical features, some of which change markedly with time. They have observed infrared-bright storms on Neptune, and very low-albedo surface regions on Titan, Saturn's largest moon, Spatial resolution on Neptune and Titan was 0.05-0.06 and 0.04-0.05 arc sec, respectively.

  5. Sliding rocks on Racetrack Playa, Death Valley National Park: first observation of rocks in motion.

    PubMed

    Norris, Richard D; Norris, James M; Lorenz, Ralph D; Ray, Jib; Jackson, Brian

    2014-01-01

    The engraved trails of rocks on the nearly flat, dry mud surface of Racetrack Playa, Death Valley National Park, have excited speculation about the movement mechanism since the 1940s. Rock movement has been variously attributed to high winds, liquid water, ice, or ice flotation, but has not been previously observed in action. We recorded the first direct scientific observation of rock movements using GPS-instrumented rocks and photography, in conjunction with a weather station and time-lapse cameras. The largest observed rock movement involved > 60 rocks on December 20, 2013 and some instrumented rocks moved up to 224 m between December 2013 and January 2014 in multiple move events. In contrast with previous hypotheses of powerful winds or thick ice floating rocks off the playa surface, the process of rock movement that we have observed occurs when the thin, 3 to 6 mm, "windowpane" ice sheet covering the playa pool begins to melt in late morning sun and breaks up under light winds of -4-5 m/s. Floating ice panels 10 s of meters in size push multiple rocks at low speeds of 2-5 m/min. along trajectories determined by the direction and velocity of the wind as well as that of the water flowing under the ice. PMID:25162535

  6. Sliding Rocks on Racetrack Playa, Death Valley National Park: First Observation of Rocks in Motion

    PubMed Central

    Lorenz, Ralph D.; Ray, Jib; Jackson, Brian

    2014-01-01

    The engraved trails of rocks on the nearly flat, dry mud surface of Racetrack Playa, Death Valley National Park, have excited speculation about the movement mechanism since the 1940s. Rock movement has been variously attributed to high winds, liquid water, ice, or ice flotation, but has not been previously observed in action. We recorded the first direct scientific observation of rock movements using GPS-instrumented rocks and photography, in conjunction with a weather station and time-lapse cameras. The largest observed rock movement involved >60 rocks on December 20, 2013 and some instrumented rocks moved up to 224 m between December 2013 and January 2014 in multiple move events. In contrast with previous hypotheses of powerful winds or thick ice floating rocks off the playa surface, the process of rock movement that we have observed occurs when the thin, 3 to 6 mm, “windowpane” ice sheet covering the playa pool begins to melt in late morning sun and breaks up under light winds of ∼4–5 m/s. Floating ice panels 10 s of meters in size push multiple rocks at low speeds of 2–5 m/min. along trajectories determined by the direction and velocity of the wind as well as that of the water flowing under the ice. PMID:25162535

  7. Observations to support adaptation: Principles, scales and decision-making

    NASA Astrophysics Data System (ADS)

    Pulwarty, R. S.

    2012-12-01

    As has been long noted, a comprehensive, coordinated observing system is the backbone of any Earth information system. Demands are increasingly placed on earth observation and prediction systems and attendant services to address the needs of economically and environmentally vulnerable sectors and investments, including energy, water, human health, transportation, agriculture, fisheries, tourism, biodiversity, and national security. Climate services include building capacity to interpret information and recognize standards and limitations of data in the promotion of social and economic development in a changing climate. This includes improving the understanding of climate in the context of a variety of temporal and spatial scales (including the influence of decadal scale forcings and land surface feedbacks on seasonal forecast reliability). Climate data and information are central for developing decision options that are sensitive to climate-related uncertainties and the design of flexible adaptation pathways. Ideally monitoring should be action oriented to support climate risk assessment and adaptation including informing robust decision making to multiple risks over the long term. Based on the experience of global observations programs and empirical research we outline- Challenges in developing effective monitoring and climate information systems to support adaptation. The types of observations of critical importance needed for sector planning to enhance food, water and energy security, and to improve early warning for disaster risk reduction Observations needed for ecosystem-based adaptation including the identification of thresholds, maintenance of biological diversity and land degradation The benefits and limits of linking regional model output to local observations including analogs and verification for adaptation planning To support these goals a robust systems of integrated observations are needed to characterize the uncertainty surrounding emergent risks

  8. The influence of normal stress and sliding velocity on the frictional behaviour of calcite at room temperature: insights from laboratory experiments and microstructural observations

    NASA Astrophysics Data System (ADS)

    Carpenter, B. M.; Collettini, C.; Viti, C.; Cavallo, A.

    2016-04-01

    The presence of calcite in and near faults, as the dominant material, cement, or vein fill, indicates that the mechanical behaviour of carbonate-dominated material likely plays an important role in shallow- and mid-crustal faulting. To better understand the behaviour of calcite, under loading conditions relevant to earthquake nucleation, we sheared powdered gouge of Carrara Marble, >98 per cent CaCO3, at constant normal stresses between 1 and 100 MPa under water-saturated conditions at room temperature. We performed slide-hold-slide tests, 1-3000 s, to measure the amount of static frictional strengthening and creep relaxation, and velocity-stepping tests, 0.1-1000 μm s-1, to evaluate frictional stability. We observe that the rates of frictional strengthening and creep relaxation decrease with increasing normal stress and diverge as shear velocity is increased from 1 to 3000 μm s-1 during slide-hold-slide experiments. We also observe complex frictional stability behaviour that depends on both normal stress and shearing velocity. At normal stresses less than 20 MPa, we observe predominantly velocity-neutral friction behaviour. Above 20 MPa, we observe strong velocity-strengthening frictional behaviour at low velocities, which then evolves towards velocity-weakening friction behaviour at high velocities. Microstructural analyses of recovered samples highlight a variety of deformation mechanisms including grain size reduction and localization, folding of calcite grains and fluid-assisted diffusion mass transfer processes promoting the development of calcite nanograins in the highly deformed portions of the experimental fault. Our combined analyses indicate that calcite fault gouge transitions from brittle to semi-brittle behaviour at high normal stress and slow sliding velocities. This transition has important implications for earthquake nucleation and propagation on faults in carbonate-dominated lithologies.

  9. Adaptive sliding mode back-stepping pitch angle control of a variable-displacement pump controlled pitch system for wind turbines.

    PubMed

    Yin, Xiu-xing; Lin, Yong-gang; Li, Wei; Liu, Hong-wei; Gu, Ya-jing

    2015-09-01

    A variable-displacement pump controlled pitch system is proposed to mitigate generator power and flap-wise load fluctuations for wind turbines. The pitch system mainly consists of a variable-displacement hydraulic pump, a fixed-displacement hydraulic motor and a gear set. The hydraulic motor can be accurately regulated by controlling the pump displacement and fluid flows to change the pitch angle through the gear set. The detailed mathematical representation and dynamic characteristics of the proposed pitch system are thoroughly analyzed. An adaptive sliding mode pump displacement controller and a back-stepping stroke piston controller are designed for the proposed pitch system such that the resulting pitch angle tracks its desired value regardless of external disturbances and uncertainties. The effectiveness and control efficiency of the proposed pitch system and controllers have been verified by using realistic dataset of a 750 kW research wind turbine.

  10. Adaptive sliding mode back-stepping pitch angle control of a variable-displacement pump controlled pitch system for wind turbines.

    PubMed

    Yin, Xiu-xing; Lin, Yong-gang; Li, Wei; Liu, Hong-wei; Gu, Ya-jing

    2015-09-01

    A variable-displacement pump controlled pitch system is proposed to mitigate generator power and flap-wise load fluctuations for wind turbines. The pitch system mainly consists of a variable-displacement hydraulic pump, a fixed-displacement hydraulic motor and a gear set. The hydraulic motor can be accurately regulated by controlling the pump displacement and fluid flows to change the pitch angle through the gear set. The detailed mathematical representation and dynamic characteristics of the proposed pitch system are thoroughly analyzed. An adaptive sliding mode pump displacement controller and a back-stepping stroke piston controller are designed for the proposed pitch system such that the resulting pitch angle tracks its desired value regardless of external disturbances and uncertainties. The effectiveness and control efficiency of the proposed pitch system and controllers have been verified by using realistic dataset of a 750 kW research wind turbine. PMID:26303957

  11. In-Situ TEM Observations of Interface Sliding and Migration in a Refined Lamellar TiAl Alloy

    SciTech Connect

    Schwartz, A J; Nieh, T G; Hsiung, L M

    2004-02-18

    The stability of lamellar interfaces in lamellar TiAl by straining at ambient temperatures has been investigated using in-situ straining techniques performed in a transmission electron microscope in order to obtain direct evidence to support the previously proposed creep mechanisms in refined lamellar TiAl based upon the interface sliding in association with the cooperative motion of interfacial dislocations. The results have revealed that both sliding and migration of lamellar interfaces can take place as a result of the cooperative motion of interfacial dislocations.

  12. Natural frequency identification of smart washer by using adaptive observer

    NASA Astrophysics Data System (ADS)

    Ito, Hitoshi; Okugawa, Masayuki

    2014-04-01

    Bolted joints are used in many machines/structures and some of them have been loosened during long time use, and unluckily these bolt loosening may cause a great accident of machines/structures system. These bolted joint, especially in important places, are main object of maintenance inspection. Maintenance inspection with human- involvement is desired to be improved owing to time-consuming, labor-intensive and high-cost. By remote and full automation monitoring of the bolt loosening, constantly monitoring of bolted joint is achieved. In order to detect loosening of bolted joints without human-involvement, applying a structural health monitoring technique and smart structures/materials concept is the key objective. In this study, a new method of bolt loosening detection by adopting a smart washer has been proposed, and the basic detection principle was discussed with numerical analysis about frequency equation of the system, was confirmed experimentally. The smart washer used in this study is in cantilever type with piezoelectric material, which adds the washer the self-sensing and actuation function. The principle used to detect the loosening of the bolts is a method of a bolt loosening detection noted that the natural frequency of a smart washer system is decreasing by the change of the bolt tightening axial tension. The feature of this proposed method is achieving to identify the natural frequency at current condition on demand by adopting the self-sensing and actuation function and system identification algorithm for varying the natural frequency depending the bolt tightening axial tension. A novel bolt loosening detection method by adopting adaptive observer is proposed in this paper. The numerical simulations are performed to verify the possibility of the adaptive observer-based loosening detection. Improvement of the detection accuracy for a bolt loosening is confirmed by adopting initial parameter and variable adaptive gain by numerical simulation.

  13. Sensor Web Dynamic Measurement Techniques and Adaptive Observing Strategies

    NASA Technical Reports Server (NTRS)

    Talabac, Stephen J.

    2004-01-01

    Sensor Web observing systems may have the potential to significantly improve our ability to monitor, understand, and predict the evolution of rapidly evolving, transient, or variable environmental features and events. This improvement will come about by integrating novel data collection techniques, new or improved instruments, emerging communications technologies and protocols, sensor mark-up languages, and interoperable planning and scheduling systems. In contrast to today's observing systems, "event-driven" sensor webs will synthesize real- or near-real time measurements and information from other platforms and then react by reconfiguring the platforms and instruments to invoke new measurement modes and adaptive observation strategies. Similarly, "model-driven" sensor webs will utilize environmental prediction models to initiate targeted sensor measurements or to use a new observing strategy. The sensor web concept contrasts with today's data collection techniques and observing system operations concepts where independent measurements are made by remote sensing and in situ platforms that do not share, and therefore cannot act upon, potentially useful complementary sensor measurement data and platform state information. This presentation describes NASA's view of event-driven and model-driven Sensor Webs and highlights several research and development activities at the Goddard Space Flight Center.

  14. Adaptive fuzzy sliding mode control for uncertain multi-input multi-output discrete-time systems using a set of noisy measurements

    NASA Astrophysics Data System (ADS)

    Yoshimura, Toshio

    2015-01-01

    This paper is concerned with the design of an adaptive fuzzy sliding mode control (AFSMC) for uncertain nonlinear multi-input multi-output (MIMO) dynamic systems using a set of noisy measurements. The dynamic systems to be considered here are described by a discrete-time nonlinear state equation with mismatched uncertainties, and the states are measured by the restriction of measurement sensors and the contamination of independent random noises. The estimates for the unmeasurable states and the uncertainties are obtained by using the weighted extended Kalman filter. In the design of the proposed AFSMC, the adaptive switching factor characterising the switching control is designed using the fuzzy inference approach where the unknown gain of the switching control is assumed to be a positive definite matrix. It is proved that under some conditions the estimation errors will converge to zero as the time tends to infinity, and the states are ultimately bounded under the action of the proposed AFSMC. The effectiveness of the proposed method is indicated through the simulation experiment of an active suspension system for a half-car model.

  15. Supersonic flutter suppression of electrorheological fluid-based adaptive panels resting on elastic foundations using sliding mode control

    NASA Astrophysics Data System (ADS)

    Hasheminejad, Seyyed M.; Nezami, M.; Aryaee Panah, M. E.

    2012-04-01

    Brief reviews on suppressing panel flutter vibrations by various active control strategies as well as utilization tunable electrorheological fluids (ERFs) for vibration control of structural systems are presented. Active suppression of the supersonic flutter motion of a simply supported sandwich panel with a tunable ERF interlayer, and coupled to an elastic foundation, is subsequently investigated. The structural formulation is based on the classical beam theory along with the Winkler-Pasternak foundation model, the ER fluid core is modeled as a first-order Kelvin-Voigt material, and the quasi-steady first-order supersonic piston theory is employed to describe the aerodynamic loading. Hamilton’s principle is used to derive a set of fully coupled dynamic equations of motion. The generalized Fourier expansions in conjunction with the Galerkin method are then employed to formulate the governing equations in the state space domain. The critical dynamic pressures at which unstable panel oscillations (coalescence of eigenvalues) occur are obtained via the p-method for selected applied electric field strengths (E = 0,2,4 kV mm-1). The classical Runge-Kutta time integration algorithm is subsequently used to calculate the open-loop aeroelastic response of the system in various basic loading configurations (i.e. uniformly distributed blast, gust, sonic boom, and step loads), with or without an interacting soft/stiff elastic foundation. Finally, a sliding mode control synthesis (SMC) involving the first six natural modes of the structural system is set up to actively suppress the closed-loop system response in supersonic flight conditions and under the imposed excitations. Simulation results demonstrate performance, effectiveness, and insensitivity with respect to the spillover of the proposed SMC-based control system. Limiting cases are considered and good agreements with the data available in the literature as well as with the computations made by using the Rayleigh

  16. Observer-based higher order sliding mode control of power factor in three-phase AC/DC converter for hybrid electric vehicle applications

    NASA Astrophysics Data System (ADS)

    Liu, Jianxing; Laghrouche, Salah; Wack, Maxime

    2014-06-01

    In this paper, a full-bridge boost power converter topology is studied for power factor control, using output higher order sliding mode control. The AC/DC converters are used for charging the battery and super-capacitor in hybrid electric vehicles from the utility. The proposed control forces the input currents to track the desired values, which can control the output voltage while keeping the power factor close to one. Super-twisting sliding mode observer is employed to estimate the input currents and load resistance only from the measurement of output voltage. Lyapunov analysis shows the asymptotic convergence of the closed-loop system to zero. Multi-rate simulation illustrates the effectiveness and robustness of the proposed controller in the presence of measurement noise.

  17. Adaptive tuning functions arise from visual observation of past movement

    PubMed Central

    Howard, Ian S.; Franklin, David W.

    2016-01-01

    Visual observation of movement plays a key role in action. For example, tennis players have little time to react to the ball, but still need to prepare the appropriate stroke. Therefore, it might be useful to use visual information about the ball trajectory to recall a specific motor memory. Past visual observation of movement (as well as passive and active arm movement) affects the learning and recall of motor memories. Moreover, when passive or active, these past contextual movements exhibit generalization (or tuning) across movement directions. Here we extend this work, examining whether visual motion also exhibits similar generalization across movement directions and whether such generalization functions can explain patterns of interference. Both the adaptation movement and contextual movement exhibited generalization beyond the training direction, with the visual contextual motion exhibiting much broader tuning. A second experiment demonstrated that this pattern was consistent with the results of an interference experiment where opposing force fields were associated with two separate visual movements. Overall, our study shows that visual contextual motion exhibits much broader (and shallower) tuning functions than previously seen for either passive or active movements, demonstrating that the tuning characteristics of past motion are highly dependent on their sensory modality. PMID:27341163

  18. SOAR Adaptive Optics Observations of the Globular Cluster NGC 6496

    NASA Astrophysics Data System (ADS)

    Fraga, Luciano; Kunder, Andrea; Tokovinin, Andrei

    2013-06-01

    We present high-quality BVRI photometric data in the field of globular cluster NGC 6496 obtained with the SOAR Telescope Adaptive Module (SAM). Our observations were collected as part of the ongoing SAM commissioning. The distance modulus and cluster color excess as found from the red clump are (m - M) V = 15.71 ± 0.02 mag and E(V - I) = 0.28 ± 0.02 mag. An age of 10.5 ± 0.5 Gyr is determined from the difference in magnitude between the red clump and the subgiant branch. These parameters are in excellent agreement with the values derived from isochrone fitting. From the color-magnitude diagram we find a metallicity of [Fe/H] = -0.65 dex and hence support a disk classification for NGC 6496. The complete BVRI data set for NGC 6469 is made available in the electronic edition of the Journal. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovação (MCTI) da República Federativa do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).

  19. Adaptive tuning functions arise from visual observation of past movement.

    PubMed

    Howard, Ian S; Franklin, David W

    2016-01-01

    Visual observation of movement plays a key role in action. For example, tennis players have little time to react to the ball, but still need to prepare the appropriate stroke. Therefore, it might be useful to use visual information about the ball trajectory to recall a specific motor memory. Past visual observation of movement (as well as passive and active arm movement) affects the learning and recall of motor memories. Moreover, when passive or active, these past contextual movements exhibit generalization (or tuning) across movement directions. Here we extend this work, examining whether visual motion also exhibits similar generalization across movement directions and whether such generalization functions can explain patterns of interference. Both the adaptation movement and contextual movement exhibited generalization beyond the training direction, with the visual contextual motion exhibiting much broader tuning. A second experiment demonstrated that this pattern was consistent with the results of an interference experiment where opposing force fields were associated with two separate visual movements. Overall, our study shows that visual contextual motion exhibits much broader (and shallower) tuning functions than previously seen for either passive or active movements, demonstrating that the tuning characteristics of past motion are highly dependent on their sensory modality. PMID:27341163

  20. Guideline adaptation and implementation planning: a prospective observational study

    PubMed Central

    2013-01-01

    Background Adaptation of high-quality practice guidelines for local use has been advanced as an efficient means to improve acceptability and applicability of evidence-informed care. In a pan-Canadian study, we examined how cancer care groups adapted pre-existing guidelines to their unique context and began implementation planning. Methods Using a mixed-methods, case-study design, five cases were purposefully sampled from self-identified groups and followed as they used a structured method and resources for guideline adaptation. Cases received the ADAPTE Collaboration toolkit, facilitation, methodological and logistical support, resources and assistance as required. Documentary and primary data collection methods captured individual case experience, including monthly summaries of meeting and field notes, email/telephone correspondence, and project records. Site visits, process audits, interviews, and a final evaluation forum with all cases contributed to a comprehensive account of participant experience. Results Study cases took 12 to >24 months to complete guideline adaptation. Although participants appreciated the structure, most found the ADAPTE method complex and lacking practical aspects. They needed assistance establishing individual guideline mandate and infrastructure, articulating health questions, executing search strategies, appraising evidence, and achieving consensus. Facilitation was described as a multi-faceted process, a team effort, and an essential ingredient for guideline adaptation. While front-line care providers implicitly identified implementation issues during adaptation, they identified a need to add an explicit implementation planning component. Conclusions Guideline adaptation is a positive initial step toward evidence-informed care, but adaptation (vs. ‘de novo’ development) did not meet expectations for reducing time or resource commitments. Undertaking adaptation is as much about the process (engagement and capacity building) as it

  1. Adaptation of lift forces in object manipulation through action observation.

    PubMed

    Reichelt, Andreas F; Ash, Alyssa M; Baugh, Lee A; Johansson, Roland S; Flanagan, J Randall

    2013-07-01

    The ability to predict accurately the weights of objects is essential for skilled and dexterous manipulation. A potentially important source of information about object weight is through the observation of other people lifting objects. Here, we tested the hypothesis that when watching an actor lift an object, people naturally learn the object's weight and use this information to scale forces when they subsequently lift the object themselves. Participants repeatedly lifted an object in turn with an actor. Object weight unpredictably changed between 2 and 7 N every 5th to 9th of the actor's lifts, and the weight lifted by the participant always matched that previously lifted by the actor. Even though the participants were uninformed about the structure of the experiment, they appropriately adapted their lifting force in the first trial after a weight change. Thus, participants updated their internal representation about the object's weight, for use in action, when watching a single lift performed by the actor. This ability presumably involves the comparison of predicted and actual sensory information related to actor's actions, a comparison process that is also fundamental in action.

  2. Photoevaporating stellar envelopes observed with Rayleigh beacon adaptive optics

    NASA Technical Reports Server (NTRS)

    Mccullough, P. R.; Fugate, R. Q.; Christou, J. C.; Ellerbroek, B. L.; Higgins, C. H.; Spinhirne, J. M.; Cleis, R. A.; Moroney, J. F.

    1995-01-01

    We present H-alpha and I-band images of a approximately 1 min diameter field centered on theta(sup 1) C Ori made with a unique adaptive optics system that uses either starlight or Rayleigh-backscattered laser light to correct for atmospheric wavefront distortion. Approximately one-half of the stars in this region are positionally associated with knots of ionized gas, which are interpreted as photoevaporating envelopes of low-mass stars. The acronyms 'partially ionized globule' (PIGs), external ionized (accretion) disks in the environs of radiation sources (EIDERs), or protoplanetary disks (ProPlyDs) all refer to these same knots. The H-alpha fluxes of the PIGs are proportional to their 2 cm radio continumm flux densities, and for nearly all the ionized knots, the 2 cm brightness temperatures are consistent with theta(sup 1) C Ori as the primary source of ionization. The comet-like morphology of the bright nebulosities is modeled as the result of an equilibrium between photoionization, recombination, and shadowing. The radii of the ionized 'head' of the cometary PIGs grow with distance from theta(sup 1) C Ori; the radii range from approximately less than or equal to 0.05 sec to approximately 0.25 sec. We interpret the size-distance relationship as evidence that the envelopes all have the same density profile and mass-loss rate within a factor of 2. Faint, arcuate wisps are observed 1 sec to 2 sec distance from some of the cometary nebulosities; these are modeled as bow shocks caused by the wind from theta(sup 1) C Ori. The positions of the stars associated with the PIGs in the observational H-R diagram indicate they are pre-main-sequence stars with masses less than approximately 3 solar mass, with approximately 1 solar mass being typical. Their medium I-K color is 2.9.

  3. Full-order sliding mode control of uncertain chaos in a permanent magnet synchronous motor based on a fuzzy extended state observer

    NASA Astrophysics Data System (ADS)

    Chen, Qiang; Nan, Yu-Rong; Zheng, Heng-Huo; Ren, Xue-Mei

    2015-11-01

    A full-order sliding mode control based on a fuzzy extended state observer is proposed to control the uncertain chaos in the permanent magnet synchronous motor. Through a simple coordinate transformation, the chaotic PMSM model is transformed into the Brunovsky canonical form, which is more suitable for the controller design. Based on the fuzzy control theory, a fuzzy extended state observer is developed to estimate the unknown states and uncertainties, and the restriction that all the system states should be completely measurable is avoided. Thereafter, a full-order sliding mode controller is designed to ensure the convergence of all system states without any chattering problem. Comparative simulations show the effectiveness and superior performance of the proposed control method. Project supported by the National Natural Science Foundation of China (Grant Nos. 61403343 and 61433003), the Scientific Research Foundation of Education Department of Zhejiang Province, China (Grant No. Y201329260), and the Natural Science Foundation of Zhejiang University of Technology, China (Grant No. 1301103053408).

  4. Output-feedback sliding-mode control via cascade observers for global stabilisation of a class of nonlinear systems with output time delay

    NASA Astrophysics Data System (ADS)

    Lobo Coutinho, Camila; Roux Oliveira, Tiago; Cunha, José Paulo V. S.

    2014-11-01

    This article proposes a sliding-mode control scheme for a class of triangular nonlinear systems with arbitrarily long and known time delay in the output signal. The proposed control strategy guarantees global asymptotic stability of the closed-loop system using only output feedback, without using any kind of approximations. The state of the system is estimated by asymptotic observers connected in cascade. The analysis of such observers in closed-loop feedback is also a contribution of the present manuscript as well as the theoretical demonstration of the chattering elimination even in the presence of delays. Simulation results and a physically motivated example with a full-bridge power converter illustrate the effectiveness of the proposed approach.

  5. Multivariable robust adaptive sliding mode control of an industrial boiler-turbine in the presence of modeling imprecisions and external disturbances: A comparison with type-I servo controller.

    PubMed

    Ghabraei, Soheil; Moradi, Hamed; Vossoughi, Gholamreza

    2015-09-01

    To guarantee the safety and efficient performance of the power plant, a robust controller for the boiler-turbine unit is needed. In this paper, a robust adaptive sliding mode controller (RASMC) is proposed to control a nonlinear multi-input multi-output (MIMO) model of industrial boiler-turbine unit, in the presence of unknown bounded uncertainties and external disturbances. To overcome the coupled nonlinearities and investigate the zero dynamics, input-output linearization is performed, and then the new decoupled inputs are derived. To tackle the uncertainties and external disturbances, appropriate adaption laws are introduced. For constructing the RASMC, suitable sliding surface is considered. To guarantee the sliding motion occurrence, appropriate control laws are constructed. Then the robustness and stability of the proposed RASMC is proved via Lyapunov stability theory. To compare the performance of the purposed RASMC with traditional control schemes, a type-I servo controller is designed. To evaluate the performance of the proposed control schemes, simulation studies on nonlinear MIMO dynamic system in the presence of high frequency bounded uncertainties and external disturbances are conducted and compared. Comparison of the results reveals the superiority of proposed RASMC over the traditional control schemes. RAMSC acts efficiently in disturbance rejection and keeping the system behavior in desirable tracking objectives, without the existence of unstable quasi-periodic solutions. PMID:25983065

  6. Multivariable robust adaptive sliding mode control of an industrial boiler-turbine in the presence of modeling imprecisions and external disturbances: A comparison with type-I servo controller.

    PubMed

    Ghabraei, Soheil; Moradi, Hamed; Vossoughi, Gholamreza

    2015-09-01

    To guarantee the safety and efficient performance of the power plant, a robust controller for the boiler-turbine unit is needed. In this paper, a robust adaptive sliding mode controller (RASMC) is proposed to control a nonlinear multi-input multi-output (MIMO) model of industrial boiler-turbine unit, in the presence of unknown bounded uncertainties and external disturbances. To overcome the coupled nonlinearities and investigate the zero dynamics, input-output linearization is performed, and then the new decoupled inputs are derived. To tackle the uncertainties and external disturbances, appropriate adaption laws are introduced. For constructing the RASMC, suitable sliding surface is considered. To guarantee the sliding motion occurrence, appropriate control laws are constructed. Then the robustness and stability of the proposed RASMC is proved via Lyapunov stability theory. To compare the performance of the purposed RASMC with traditional control schemes, a type-I servo controller is designed. To evaluate the performance of the proposed control schemes, simulation studies on nonlinear MIMO dynamic system in the presence of high frequency bounded uncertainties and external disturbances are conducted and compared. Comparison of the results reveals the superiority of proposed RASMC over the traditional control schemes. RAMSC acts efficiently in disturbance rejection and keeping the system behavior in desirable tracking objectives, without the existence of unstable quasi-periodic solutions.

  7. Probing the functions of contextual modulation by adapting images rather than observers

    PubMed Central

    Webster, Michael A.

    2014-01-01

    Countless visual aftereffects have illustrated how visual sensitivity and perception can be biased by adaptation to the recent temporal context. This contextual modulation has been proposed to serve a variety of functions, but the actual benefits of adaptation remain uncertain. We describe an approach we have recently developed for exploring these benefits by adapting images instead of observers, to simulate how images should appear under theoretically optimal states of adaptation. This allows the long-term consequences of adaptation to be evaluated in ways that are difficult to probe by adapting observers, and provides a common framework for understanding how visual coding changes when the environment or the observer changes, or for evaluating how the effects of temporal context depend on different models of visual coding or the adaptation processes. The approach is illustrated for the specific case of adaptation to color, for which the initial neural coding and adaptation processes are relatively well understood, but can in principle be applied to examine the consequences of adaptation for any stimulus dimension. A simple calibration that adjusts each neuron’s sensitivity according to the stimulus level it is exposed to is sufficient to normalize visual coding and generate a host of benefits, from increased efficiency to perceptual constancy to enhanced discrimination. This temporal normalization may also provide an important precursor for the effective operation of contextual mechanisms operating across space or feature dimensions. To the extent that the effects of adaptation can be predicted, images from new environments could be “pre-adapted” to match them to the observer, eliminating the need for observers to adapt. PMID:25281412

  8. "High Angular Resolution Observations of Protoplanetary Disks with Adaptive Optics"

    NASA Technical Reports Server (NTRS)

    Roddier, Francois

    1999-01-01

    Significant results were obtained and published in the literature. The first optical detection of a circumbinary disk was reported in the ApJ at millimetric wavelengths. The size and inclination of this disk were found to be consistent with millimetric observations. Evidence was found for a cavity inside the disk as theory predicts from dust clearing by the stellar companion.

  9. The combined effects of action observation and passive proprioceptive training on adaptive motor learning.

    PubMed

    Lei, Yuming; Bao, Shancheng; Wang, Jinsung

    2016-09-01

    Sensorimotor adaptation can be induced by action observation, and also by passive training. Here, we investigated the effect of a protocol that combined action observation and passive training on visuomotor adaptation, by comparing it with the effect of action observation or passive training alone. Subjects were divided into five conditions during the training session: (1) action observation, in which the subjects watched a video of a model who adapted to a novel visuomotor rotation; (2) proprioceptive training, in which the subject's arm was moved passively to target locations that were associated with desired trajectories; (3) combined training, in which the subjects watched the video of a model during a half of the session and experienced passive movements during the other half; (4) active training, in which the subjects adapted actively to the rotation; and (5) a control condition, in which the subjects did not perform any task. Following that session, all subjects adapted to the same visuomotor rotation. Results showed that the subjects in the combined training condition adapted to the rotation significantly better than those in the observation or proprioceptive training condition, although their performance was not as good as that of those who adapted actively. These findings suggest that although a protocol that combines action observation and passive training consists of all the processes involved in active training (error detection and correction, effector-specific and proprioceptively based reaching movements), these processes in that protocol may work differently as compared to a protocol in which the same processes are engaged actively.

  10. ADAPTIVE MATCHING IN RANDOMIZED TRIALS AND OBSERVATIONAL STUDIES

    PubMed Central

    van der Laan, Mark J.; Balzer, Laura B.; Petersen, Maya L.

    2014-01-01

    SUMMARY In many randomized and observational studies the allocation of treatment among a sample of n independent and identically distributed units is a function of the covariates of all sampled units. As a result, the treatment labels among the units are possibly dependent, complicating estimation and posing challenges for statistical inference. For example, cluster randomized trials frequently sample communities from some target population, construct matched pairs of communities from those included in the sample based on some metric of similarity in baseline community characteristics, and then randomly allocate a treatment and a control intervention within each matched pair. In this case, the observed data can neither be represented as the realization of n independent random variables, nor, contrary to current practice, as the realization of n/2 independent random variables (treating the matched pair as the independent sampling unit). In this paper we study estimation of the average causal effect of a treatment under experimental designs in which treatment allocation potentially depends on the pre-intervention covariates of all units included in the sample. We define efficient targeted minimum loss based estimators for this general design, present a theorem that establishes the desired asymptotic normality of these estimators and allows for asymptotically valid statistical inference, and discuss implementation of these estimators. We further investigate the relative asymptotic efficiency of this design compared with a design in which unit-specific treatment assignment depends only on the units’ covariates. Our findings have practical implications for the optimal design and analysis of pair matched cluster randomized trials, as well as for observational studies in which treatment decisions may depend on characteristics of the entire sample. PMID:25097298

  11. Dust Slides

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03677 Linear Clouds

    Dust slides are common in the dust covered region called Lycus Sulci. A large fracture is also visible in this image.

    Image information: VIS instrument. Latitude 28.1N, Longitude 226.3E. 18 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  12. Partial Adaptation of Obtained and Observed Value Signals Preserves Information about Gains and Losses

    PubMed Central

    Baddeley, Michelle; Tobler, Philippe N.; Schultz, Wolfram

    2016-01-01

    Given that the range of rewarding and punishing outcomes of actions is large but neural coding capacity is limited, efficient processing of outcomes by the brain is necessary. One mechanism to increase efficiency is to rescale neural output to the range of outcomes expected in the current context, and process only experienced deviations from this expectation. However, this mechanism comes at the cost of not being able to discriminate between unexpectedly low losses when times are bad versus unexpectedly high gains when times are good. Thus, too much adaptation would result in disregarding information about the nature and absolute magnitude of outcomes, preventing learning about the longer-term value structure of the environment. Here we investigate the degree of adaptation in outcome coding brain regions in humans, for directly experienced outcomes and observed outcomes. We scanned participants while they performed a social learning task in gain and loss blocks. Multivariate pattern analysis showed two distinct networks of brain regions adapt to the most likely outcomes within a block. Frontostriatal areas adapted to directly experienced outcomes, whereas lateral frontal and temporoparietal regions adapted to observed social outcomes. Critically, in both cases, adaptation was incomplete and information about whether the outcomes arose in a gain block or a loss block was retained. Univariate analysis confirmed incomplete adaptive coding in these regions but also detected nonadapting outcome signals. Thus, although neural areas rescale their responses to outcomes for efficient coding, they adapt incompletely and keep track of the longer-term incentives available in the environment. SIGNIFICANCE STATEMENT Optimal value-based choice requires that the brain precisely and efficiently represents positive and negative outcomes. One way to increase efficiency is to adapt responding to the most likely outcomes in a given context. However, too strong adaptation would result

  13. Filter accuracy for the Lorenz 96 model: Fixed versus adaptive observation operators

    NASA Astrophysics Data System (ADS)

    Law, K. J. H.; Sanz-Alonso, D.; Shukla, A.; Stuart, A. M.

    2016-06-01

    In the context of filtering chaotic dynamical systems it is well-known that partial observations, if sufficiently informative, can be used to control the inherent uncertainty due to chaos. The purpose of this paper is to investigate, both theoretically and numerically, conditions on the observations of chaotic systems under which they can be accurately filtered. In particular, we highlight the advantage of adaptive observation operators over fixed ones. The Lorenz '96 model is used to exemplify our findings. We consider discrete-time and continuous-time observations in our theoretical developments. We prove that, for fixed observation operator, the 3DVAR filter can recover the system state within a neighbourhood determined by the size of the observational noise. It is required that a sufficiently large proportion of the state vector is observed, and an explicit form for such sufficient fixed observation operator is given. Numerical experiments, where the data is incorporated by use of the 3DVAR and extended Kalman filters, suggest that less informative fixed operators than given by our theory can still lead to accurate signal reconstruction. Adaptive observation operators are then studied numerically; we show that, for carefully chosen adaptive observation operators, the proportion of the state vector that needs to be observed is drastically smaller than with a fixed observation operator. Indeed, we show that the number of state coordinates that need to be observed may even be significantly smaller than the total number of positive Lyapunov exponents of the underlying system.

  14. Comparing and contrasting observed adaptations in three deltas: the Ganges-Meghna-Brahmaputra, Mahanadi and Volta

    NASA Astrophysics Data System (ADS)

    Nicholls, R. J.; Suckall, N.; Mensah, A.; Mondal, S.; Dey, S.; Hazra, S.

    2015-12-01

    In low and middle-income countries, many deltaic communities directly depend on the natural environment for income and well-being. Current environmental concerns that threaten deltaic communities, such as increasing salinity, sedimentation, erosion and subsidence are likely to be exacerbated by climate change and variability, for example sea-level rise, increased storminess and rising temperatures. Such changes, along with other social and environmental stressors, mean that communities must adapt. This paper outlines findings of a systematic review of the peer-reviewed and grey literature that examines observed adaptations in three deltas of differing sizes in various geographical contexts: the Ganges-Meghna-Brahmaputra in India and Bangladesh, the Mahanadi in India, and the Volta in Ghana. It compares and contrasts various elements of observed adaptations, including who is driving the adaptation, the beneficiaries, barriers to participation and evidence for maladaptation. The predominant drivers of adaptation vary from government (at state level in India and national level in Bangladesh) and NGOs (in Ghana). Autonomous adaptations are not widely reported in the literature from any of the deltas. In all three deltas there is a focus on supporting adaptation in farming rather than fishing; despite the fact that fisheries contribute to local food security as well as national economies. Lack of access to financial, natural, physical and human capital are common barriers to adaptation in all three deltas. Additionally the Indian literature in particular highlights the lack of coordination between different government departments, coupled with an excessively top-down (state-driven) approach to adaptation. Maladaptation is most commonly reported in the literature from Bangladesh, for example, loss of employment of inland fishermen in embanked areas. The paper concludes by highlighting some of the implications of these findings for adaptation policy in deltas.

  15. Apparatus Would Stain Microscope Slides

    NASA Technical Reports Server (NTRS)

    Breeding, James D.

    1993-01-01

    Proposed apparatus meters specific amounts of fluid out of containers at specific times to stain microscope slides. Intended specifically for semiautomated staining of microbiological and hematological samples in microgravity, leakproof apparatus used in other environments in which technicians have little time to allocate to staining procedures and/or exposure to toxic staining agents or to micro-organisms to be stained hazardous. Apparatus adapted to perform almost any staining procedure and accommodates multiple staining reagents, useful for small or remote clinical laboratories.

  16. Phase and speed synchronization control of four eccentric rotors driven by induction motors in a linear vibratory feeder with unknown time-varying load torques using adaptive sliding mode control algorithm

    NASA Astrophysics Data System (ADS)

    Kong, Xiangxi; Zhang, Xueliang; Chen, Xiaozhe; Wen, Bangchun; Wang, Bo

    2016-05-01

    In this paper, phase and speed synchronization control of four eccentric rotors (ERs) driven by induction motors in a linear vibratory feeder with unknown time-varying load torques is studied. Firstly, the electromechanical coupling model of the linear vibratory feeder is established by associating induction motor's model with the dynamic model of the system, which is a typical under actuated model. According to the characteristics of the linear vibratory feeder, the complex control problem of the under actuated electromechanical coupling model converts to phase and speed synchronization control of four ERs. In order to keep the four ERs operating synchronously with zero phase differences, phase and speed synchronization controllers are designed by employing adaptive sliding mode control (ASMC) algorithm via a modified master-slave structure. The stability of the controllers is proved by Lyapunov stability theorem. The proposed controllers are verified by simulation via Matlab/Simulink program and compared with the conventional sliding mode control (SMC) algorithm. The results show the proposed controllers can reject the time-varying load torques effectively and four ERs can operate synchronously with zero phase differences. Moreover, the control performance is better than the conventional SMC algorithm and the chattering phenomenon is attenuated. Furthermore, the effects of reference speed and parametric perturbations are discussed to show the strong robustness of the proposed controllers. Finally, experiments on a simple vibratory test bench are operated by using the proposed controllers and without control, respectively, to validate the effectiveness of the proposed controllers further.

  17. Designing a Stochastic Adaptive Impulsive Observer for Stochastic Linear and Nonlinear Impulsive Systems

    SciTech Connect

    Ayati, Moosa; Alwan, Mohamad; Liu Xinzhi; Khaloozadeh, Hamid

    2011-11-30

    State observation (estimation) is a very important issue in system analysis and control. This paper develops a new observer called Stochastic Adaptive Impulsive Observer (SAIO) for the state estimation of impulsive systems. The proposed observer is applicable to linear and nonlinear stochastic impulsive systems. In addition, the effect of parametric uncertainty is considered and unknown parameters of the system are estimated by suitable adaptation laws. Impulsive system theory, particularly stochastic Lyapunov-like function, is used to analyze the stability and convergence of the state estimations. The main advantages of the proposed observer are: 1) it gives continuous estimation from discrete time measurements of the system output, and 2) it is useful for state estimation when continuous measurements are impossible or expensive. Simulation results show the effectiveness of the proposed observer and we believe that it has many applications in control and estimation theories.

  18. Sliding vane geometry turbines

    DOEpatents

    Sun, Harold Huimin; Zhang, Jizhong; Hu, Liangjun; Hanna, Dave R

    2014-12-30

    Various systems and methods are described for a variable geometry turbine. In one example, a turbine nozzle comprises a central axis and a nozzle vane. The nozzle vane includes a stationary vane and a sliding vane. The sliding vane is positioned to slide in a direction substantially tangent to an inner circumference of the turbine nozzle and in contact with the stationary vane.

  19. Teach Classification with Slides.

    ERIC Educational Resources Information Center

    Franks, Deborah

    1980-01-01

    Described is a creative approach to the use of contact slides as a means of student participation in a learning unit on animal classification. The finished product is a slide presentation in which students themselves have made the slides and taped the narration. (CS)

  20. Filter accuracy for the Lorenz 96 model: Fixed versus adaptive observation operators

    DOE PAGES

    Stuart, Andrew M.; Shukla, Abhishek; Sanz-Alonso, Daniel; Law, K. J. H.

    2016-02-23

    In the context of filtering chaotic dynamical systems it is well-known that partial observations, if sufficiently informative, can be used to control the inherent uncertainty due to chaos. The purpose of this paper is to investigate, both theoretically and numerically, conditions on the observations of chaotic systems under which they can be accurately filtered. In particular, we highlight the advantage of adaptive observation operators over fixed ones. The Lorenz ’96 model is used to exemplify our findings. Here, we consider discrete-time and continuous-time observations in our theoretical developments. We prove that, for fixed observation operator, the 3DVAR filter can recovermore » the system state within a neighbourhood determined by the size of the observational noise. It is required that a sufficiently large proportion of the state vector is observed, and an explicit form for such sufficient fixed observation operator is given. Numerical experiments, where the data is incorporated by use of the 3DVAR and extended Kalman filters, suggest that less informative fixed operators than given by our theory can still lead to accurate signal reconstruction. Adaptive observation operators are then studied numerically; we show that, for carefully chosen adaptive observation operators, the proportion of the state vector that needs to be observed is drastically smaller than with a fixed observation operator. Indeed, we show that the number of state coordinates that need to be observed may even be significantly smaller than the total number of positive Lyapunov exponents of the underlying system.« less

  1. Application of Sliding Mode Methods to the Design of Reconfigurable Flight Control Systems

    NASA Technical Reports Server (NTRS)

    Wells, Scott R.

    2002-01-01

    Observer-based sliding mode control is investigated for application to aircraft reconfigurable flight control. A comprehensive overview of reconfigurable flight control is given, including, a review of the current state-of-the-art within the subdisciplines of fault detection, parameter identification, adaptive control schemes, and dynamic control allocation. Of the adaptive control methods reviewed, sliding mode control (SMC) appears very promising due its property of invariance to matched uncertainty. An overview of sliding mode control is given and its remarkable properties are demonstrated by example. Sliding mode methods, however, are difficult to implement because unmodeled parasitic dynamics cause immediate and severe instability. This presents a challenge for all practical applications with limited bandwidth actuators. One method to deal with parasitic dynamics is the use of an asymptotic observer in the feedback path. Observer-based SMC is investigated, and a method for selecting observer gains is offered. An additional method for shaping the feedback loop using a filter is also developed. It is shown that this SMC prefilter is equivalent to a form of model reference hedging. A complete design procedure is given which takes advantage of the sliding mode boundary layer to recast the SMC as a linear control law. Frequency domain loop shaping is then used to design the sliding manifold. Finally, three aircraft applications are demonstrated. An F-18/HARV is used to demonstrate a SISO pitch rate tracking controller. It is also used to demonstrate a MIMO lateral-directional roll rate tracking controller. The last application is a full linear six degree-of-freedom advanced tailless fighter model. The observer-based SMC is seen to provide excellent tracking with superior robustness to parameter changes and actuator failures.

  2. Five Methods to Score the Teacher Observation of Classroom Adaptation Checklist and to Examine Group Differences

    ERIC Educational Resources Information Center

    Wang, Ze; Rohrer, David; Chuang, Chi-ching; Fujiki, Mayo; Herman, Keith; Reinke, Wendy

    2015-01-01

    This study compared 5 scoring methods in terms of their statistical assumptions. They were then used to score the Teacher Observation of Classroom Adaptation Checklist, a measure consisting of 3 subscales and 21 Likert-type items. The 5 methods used were (a) sum/average scores of items, (b) latent factor scores with continuous indicators, (c)…

  3. Observed-Based Adaptive Fuzzy Tracking Control for Switched Nonlinear Systems With Dead-Zone.

    PubMed

    Tong, Shaocheng; Sui, Shuai; Li, Yongming

    2015-12-01

    In this paper, the problem of adaptive fuzzy output-feedback control is investigated for a class of uncertain switched nonlinear systems in strict-feedback form. The considered switched systems contain unknown nonlinearities, dead-zone, and immeasurable states. Fuzzy logic systems are utilized to approximate the unknown nonlinear functions, a switched fuzzy state observer is designed and thus the immeasurable states are obtained by it. By applying the adaptive backstepping design principle and the average dwell time method, an adaptive fuzzy output-feedback tracking control approach is developed. It is proved that the proposed control approach can guarantee that all the variables in the closed-loop system are bounded under a class of switching signals with average dwell time, and also that the system output can track a given reference signal as closely as possible. The simulation results are given to check the effectiveness of the proposed approach.

  4. Neural-network-observer-based optimal control for unknown nonlinear systems using adaptive dynamic programming

    NASA Astrophysics Data System (ADS)

    Liu, Derong; Huang, Yuzhu; Wang, Ding; Wei, Qinglai

    2013-09-01

    In this paper, an observer-based optimal control scheme is developed for unknown nonlinear systems using adaptive dynamic programming (ADP) algorithm. First, a neural-network (NN) observer is designed to estimate system states. Then, based on the observed states, a neuro-controller is constructed via ADP method to obtain the optimal control. In this design, two NN structures are used: a three-layer NN is used to construct the observer which can be applied to systems with higher degrees of nonlinearity and without a priori knowledge of system dynamics, and a critic NN is employed to approximate the value function. The optimal control law is computed using the critic NN and the observer NN. Uniform ultimate boundedness of the closed-loop system is guaranteed. The actor, critic, and observer structures are all implemented in real-time, continuously and simultaneously. Finally, simulation results are presented to demonstrate the effectiveness of the proposed control scheme.

  5. The 2004 Opposition of Ceres Observed with Adaptive Optics on the VLT

    NASA Technical Reports Server (NTRS)

    Erard, S.; Frorni, O.; Ollivier, M.; Dotto, E.; Roush, T.; Poulet, F.; Mueller, T.

    2005-01-01

    The close opposition of Ceres in January 2004 has been observed with the NACO adaptive optics system on the VLT. Both imaging and spectroscopy were performed in the 1.1-4.1 m range. Extensive longitudinal coverage was acquired during a three days run, with spatial resolution up to 50 km in imaging mode. The scientific objectives are 1) to provide the first IR map of Ceres; 2) to map possible compositional variations at the surface. Only imaging results are presented here.

  6. Texturing in metals as a result of sliding

    NASA Technical Reports Server (NTRS)

    Wheeler, D. R.; Buckley, D. H.

    1973-01-01

    Sliding friction experiments were conducted with copper, nickel, iron, and cobalt sliding on themselves in air and argon. The resulting wear surfaces were examined with X-ray analysis to determine if surface texturing had occurred as a result of sliding. Results of the investigation indicate that, for the face-centered-cubic metals copper and nickel, a (111) texture develops with the (111) planes tilted 10 deg in the direction of sliding. The body-centered-cubic metal iron exhibited a (110) texture with the (100) direction oriented in the direction of sliding. It also exhibited a 10 deg tilt in the direction of sliding. The environment influenced the results in that the degree of texture observed in argon was less than that seen in air for iron. No texturing was observed for the close-packed-hexagonal metal cobalt. Recrystallization was observed with copper as a result of sliding.

  7. 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.

  8. Adaptive super-twisting observer for estimation of random road excitation profile in automotive suspension systems.

    PubMed

    Rath, J J; Veluvolu, K C; Defoort, M

    2014-01-01

    The estimation of road excitation profile is important for evaluation of vehicle stability and vehicle suspension performance for autonomous vehicle control systems. In this work, the nonlinear dynamics of the active automotive system that is excited by the unknown road excitation profile are considered for modeling. To address the issue of estimation of road profile, we develop an adaptive supertwisting observer for state and unknown road profile estimation. Under Lipschitz conditions for the nonlinear functions, the convergence of the estimation error is proven. Simulation results with Ford Fiesta MK2 demonstrate the effectiveness of the proposed observer for state and unknown input estimation for nonlinear active suspension system. PMID:24683321

  9. Adaptive super-twisting observer for estimation of random road excitation profile in automotive suspension systems.

    PubMed

    Rath, J J; Veluvolu, K C; Defoort, M

    2014-01-01

    The estimation of road excitation profile is important for evaluation of vehicle stability and vehicle suspension performance for autonomous vehicle control systems. In this work, the nonlinear dynamics of the active automotive system that is excited by the unknown road excitation profile are considered for modeling. To address the issue of estimation of road profile, we develop an adaptive supertwisting observer for state and unknown road profile estimation. Under Lipschitz conditions for the nonlinear functions, the convergence of the estimation error is proven. Simulation results with Ford Fiesta MK2 demonstrate the effectiveness of the proposed observer for state and unknown input estimation for nonlinear active suspension system.

  10. Adaptive Super-Twisting Observer for Estimation of Random Road Excitation Profile in Automotive Suspension Systems

    PubMed Central

    Rath, J. J.; Veluvolu, K. C.; Defoort, M.

    2014-01-01

    The estimation of road excitation profile is important for evaluation of vehicle stability and vehicle suspension performance for autonomous vehicle control systems. In this work, the nonlinear dynamics of the active automotive system that is excited by the unknown road excitation profile are considered for modeling. To address the issue of estimation of road profile, we develop an adaptive supertwisting observer for state and unknown road profile estimation. Under Lipschitz conditions for the nonlinear functions, the convergence of the estimation error is proven. Simulation results with Ford Fiesta MK2 demonstrate the effectiveness of the proposed observer for state and unknown input estimation for nonlinear active suspension system. PMID:24683321

  11. Mailing microscope slides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many insects feed agriculturally important crops, trees, and ornamental plants and cause millions of dollars of damage annually. Identification for some of these require the preparation of a microscope slide for examination. There are times when a microscope slide may need to be sent away to a speci...

  12. Improve earthquake hypocenter using adaptive simulated annealing inversion in regional tectonic, volcano tectonic, and geothermal observation

    SciTech Connect

    Ry, Rexha Verdhora; Nugraha, Andri Dian

    2015-04-24

    Observation of earthquakes is routinely used widely in tectonic activity observation, and also in local scale such as volcano tectonic and geothermal activity observation. It is necessary for determining the location of precise hypocenter which the process involves finding a hypocenter location that has minimum error between the observed and the calculated travel times. When solving this nonlinear inverse problem, simulated annealing inversion method can be applied to such global optimization problems, which the convergence of its solution is independent of the initial model. In this study, we developed own program codeby applying adaptive simulated annealing inversion in Matlab environment. We applied this method to determine earthquake hypocenter using several data cases which are regional tectonic, volcano tectonic, and geothermal field. The travel times were calculated using ray tracing shooting method. We then compared its results with the results using Geiger’s method to analyze its reliability. Our results show hypocenter location has smaller RMS error compared to the Geiger’s result that can be statistically associated with better solution. The hypocenter of earthquakes also well correlated with geological structure in the study area. Werecommend using adaptive simulated annealing inversion to relocate hypocenter location in purpose to get precise and accurate earthquake location.

  13. 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

  14. Binary stars observed with adaptive optics at the starfire optical range

    SciTech Connect

    Drummond, Jack D.

    2014-03-01

    In reviewing observations taken of binary stars used as calibration objects for non-astronomical purposes with adaptive optics on the 3.5 m Starfire Optical Range telescope over the past 2 years, one-fifth of them were found to be off-orbit. In order to understand such a high number of discrepant position angles and separations, all previous observations in the Washington Double Star Catalog for these rogue binaries were obtained from the Naval Observatory. Adding our observations to these yields new orbits for all, resolving the discrepancies. We have detected both components of γ Gem for the first time, and we have shown that 7 Cam is an optical pair, not physically bound.

  15. A Combined Simple Adaptive Control with Disturbance Observer for a Class of Time-Delay Systems

    NASA Astrophysics Data System (ADS)

    Son, Young Ik; Jeong, Goo-Jong; Kim, In Hyuk

    Disturbance attenuation for a class of time-delay systems is performed by a combined simple adaptive control (SAC) with a new configuration of disturbance observer (DOB). The nominal system results from the Pade approximation, which is in the form of a non-minimum phase LTI system. For the implementation of SAC and DOB, two parallel feedforward compensators (PFC) are designed with the inverses of PD- and PID-controller, respectively. Simulation results show the effectiveness of the proposed controller to compensate the disturbance response and uncertain delay time.

  16. Adaptive neuro-fuzzy inference system for temperature and humidity profile retrieval from microwave radiometer observations

    NASA Astrophysics Data System (ADS)

    Ramesh, K.; Kesarkar, A. P.; Bhate, J.; Venkat Ratnam, M.; Jayaraman, A.

    2015-01-01

    The retrieval of accurate profiles of temperature and water vapour is important for the study of atmospheric convection. Recent development in computational techniques motivated us to use adaptive techniques in the retrieval algorithms. In this work, we have used an adaptive neuro-fuzzy inference system (ANFIS) to retrieve profiles of temperature and humidity up to 10 km over the tropical station Gadanki (13.5° N, 79.2° E), India. ANFIS is trained by using observations of temperature and humidity measurements by co-located Meisei GPS radiosonde (henceforth referred to as radiosonde) and microwave brightness temperatures observed by radiometrics multichannel microwave radiometer MP3000 (MWR). ANFIS is trained by considering these observations during rainy and non-rainy days (ANFIS(RD + NRD)) and during non-rainy days only (ANFIS(NRD)). The comparison of ANFIS(RD + NRD) and ANFIS(NRD) profiles with independent radiosonde observations and profiles retrieved using multivariate linear regression (MVLR: RD + NRD and NRD) and artificial neural network (ANN) indicated that the errors in the ANFIS(RD + NRD) are less compared to other retrieval methods. The Pearson product movement correlation coefficient (r) between retrieved and observed profiles is more than 92% for temperature profiles for all techniques and more than 99% for the ANFIS(RD + NRD) technique Therefore this new techniques is relatively better for the retrieval of temperature profiles. The comparison of bias, mean absolute error (MAE), RMSE and symmetric mean absolute percentage error (SMAPE) of retrieved temperature and relative humidity (RH) profiles using ANN and ANFIS also indicated that profiles retrieved using ANFIS(RD + NRD) are significantly better compared to the ANN technique. The analysis of profiles concludes that retrieved profiles using ANFIS techniques have improved the temperature retrievals substantially; however, the retrieval of RH by all techniques considered in this paper (ANN, MVLR and

  17. Flexible Description and Adaptive Processing of Earth Observation Data through the BigEarth Platform

    NASA Astrophysics Data System (ADS)

    Gorgan, Dorian; Bacu, Victor; Stefanut, Teodor; Nandra, Cosmin; Mihon, Danut

    2016-04-01

    The Earth Observation data repositories extending periodically by several terabytes become a critical issue for organizations. The management of the storage capacity of such big datasets, accessing policy, data protection, searching, and complex processing require high costs that impose efficient solutions to balance the cost and value of data. Data can create value only when it is used, and the data protection has to be oriented toward allowing innovation that sometimes depends on creative people, which achieve unexpected valuable results through a flexible and adaptive manner. The users need to describe and experiment themselves different complex algorithms through analytics in order to valorize data. The analytics uses descriptive and predictive models to gain valuable knowledge and information from data analysis. Possible solutions for advanced processing of big Earth Observation data are given by the HPC platforms such as cloud. With platforms becoming more complex and heterogeneous, the developing of applications is even harder and the efficient mapping of these applications to a suitable and optimum platform, working on huge distributed data repositories, is challenging and complex as well, even by using specialized software services. From the user point of view, an optimum environment gives acceptable execution times, offers a high level of usability by hiding the complexity of computing infrastructure, and supports an open accessibility and control to application entities and functionality. The BigEarth platform [1] supports the entire flow of flexible description of processing by basic operators and adaptive execution over cloud infrastructure [2]. The basic modules of the pipeline such as the KEOPS [3] set of basic operators, the WorDeL language [4], the Planner for sequential and parallel processing, and the Executor through virtual machines, are detailed as the main components of the BigEarth platform [5]. The presentation exemplifies the development

  18. Slides, Swings and Science.

    ERIC Educational Resources Information Center

    Dreyer, Kay Jardon; Bryte, Janelle

    1990-01-01

    Described are eight science activities that may take place on a school playground using a parachute, balls, swings, slides, and a balance beam. Procedures and questions for each activity are included. (CW)

  19. Water-slide alopecia.

    PubMed

    Adams, B B

    2001-05-01

    A 29-year-old male presented with large, symmetric, alopecic patches on the posterolateral aspects of both calves. A detailed history revealed that the individual had recently attended a water-slide amusement park. Repeated frictional trauma between the legs and the slide resulted in these alopecic patches. Friction, especially when encountered during sports-related and recreational activities, should be included in the differential diagnosis of well-defined alopecic patches.

  20. Prototype Slide Stainer

    NASA Technical Reports Server (NTRS)

    1971-01-01

    The prototype slide staining system capable of performing both one-component Wright's staining of blood smears and eight-step Gram staining of heat fixed slides of microorganisms is described. Attention was given to liquid containment, waste handling, absence of contamination from previous staining, and stability of the staining reagents. The unit is self-contained, capable of independent operation under one- or zero-g conditions, and compatible with Skylab A.

  1. Fundamentals of the Slide Library.

    ERIC Educational Resources Information Center

    Boerner, Susan Zee

    This paper is an introduction to the fundamentals of the art (including architecture) slide library, with some emphasis on basic procedures of the science slide library. Information in this paper is particularly relevant to the college, university, and museum slide library. Topics addressed include: (1) history of the slide library; (2) duties of…

  2. Selected Landscape Plants. Slide Script.

    ERIC Educational Resources Information Center

    McCann, Kevin

    This slide script, part of a series of slide scripts designed for use in vocational agriculture classes, deals with commercially important woody ornamental landscape plants. Included in the script are narrations for use with a total of 253 slides illustrating 92 different plants. Several slides are used to illustrate each plant: besides a view of…

  3. Ornamental Landscape Grasses. Slide Script.

    ERIC Educational Resources Information Center

    Still, Steven M.; Adams, Denise W.

    This slide script to accompany the slide series, Ornamental Landscape Grasses, contains photographs of the 167 slides and accompanying narrative text intended for use in the study and identification of commercially important ornamental grasses and grasslike plants. Narrative text is provided for slides of 62 different perennial and annual species…

  4. An Airship Slide Rule

    NASA Technical Reports Server (NTRS)

    Weaver, E R; Pickering, S F

    1924-01-01

    This report prepared for the National Advisory Committee for Aeronautics, describes an airship slide rule developed by the Gas-Chemistry Section of the Bureau of Standards, at the request of the Bureau of Engineering of the Navy Department. It is intended primarily to give rapid solutions of a few problems of frequent occurrence in airship navigation, but it can be used to advantage in solving a great variety of problems, involving volumes, lifting powers, temperatures, pressures, altitudes and the purity of the balloon gas. The rule is graduated to read directly in the units actually used in making observations, constants and conversion factors being taken care of by the length and location of the scales. It is thought that with this rule practically any problem likely to arise in this class of work can be readily solved after the user has become familiar with the operation of the rule; and that the solution will, in most cases, be as accurate as the data warrant.

  5. Hybrid neural network fraction integral terminal sliding mode control of an Inchworm robot manipulator

    NASA Astrophysics Data System (ADS)

    Rahmani, Mehran; Ghanbari, Ahmad; Ettefagh, Mir Mohammad

    2016-12-01

    This paper proposes a control scheme based on the fraction integral terminal sliding mode control and adaptive neural network. It deals with the system model uncertainties and the disturbances to improve the control performance of the Inchworm robot manipulator. A fraction integral terminal sliding mode control applies to the Inchworm robot manipulator to obtain the initial stability. Also, an adaptive neural network is designed to approximate the system uncertainties and unknown disturbances to reduce chattering phenomena. The weight matrix of the proposed adaptive neural network can be updated online, according to the current state error information. The stability of the proposed control method is proved by Lyapunov theory. The performance of the adaptive neural network fraction integral terminal sliding mode control is compared with three other conventional controllers such as sliding mode control, integral terminal sliding mode control and fraction integral terminal sliding mode control. Simulation results show the effectiveness of the proposed control method.

  6. New analytical expressions of the Rossiter-McLaughlin effect adapted to different observation techniques

    NASA Astrophysics Data System (ADS)

    Boué, G.; Montalto, M.; Boisse, I.; Oshagh, M.; Santos, N. C.

    2013-02-01

    The Rossiter-McLaughlin (hereafter RM) effect is a key tool for measuring the projected spin-orbit angle between stellar spin axes and orbits of transiting planets. However, the measured radial velocity (RV) anomalies produced by this effect are not intrinsic and depend on both instrumental resolution and data reduction routines. Using inappropriate formulas to model the RM effect introduces biases, at least in the projected velocity Vsini⋆ compared to the spectroscopic value. Currently, only the iodine cell technique has been modeled, which corresponds to observations done by, e.g., the HIRES spectrograph of the Keck telescope. In this paper, we provide a simple expression of the RM effect specially designed to model observations done by the Gaussian fit of a cross-correlation function (CCF) as in the routines performed by the HARPS team. We derived a new analytical formulation of the RV anomaly associated to the iodine cell technique. For both formulas, we modeled the subplanet mean velocity vp and dispersion βp accurately taking the rotational broadening on the subplanet profile into account. We compare our formulas adapted to the CCF technique with simulated data generated with the numerical software SOAP-T and find good agreement up to Vsini⋆ ≲ 20 km s-1. In contrast, the analytical models simulating the two different observation techniques can disagree by about 10σ in Vsini⋆ for large spin-orbit misalignments. It is thus important to apply the adapted model when fitting data. A public code implementing the expressions derived in this paper is available at http://www.astro.up.pt/resources/arome. A copy of the code is also available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/550/A53

  7. High-resolution lidar observations of mesospheric sodium and implications for adaptive optics.

    PubMed

    Pfrommer, Thomas; Hickson, Paul

    2010-11-01

    Observations of sodium density variability in the upper mesosphere/lower thermosphere, obtained using a high-resolution lidar system, show rapid fluctuations in the sodium centroid altitude. The temporal power spectrum extends above 1 Hz and is well-fit by a power law having a slope that is -1.95±0.12. These fluctuations produce focus errors in adaptive optics systems employing continuous-wave sodium laser guide stars, which can be significant for large-aperture telescopes. For a 30 m aperture diameter, the associated rms wavefront error is approximately 4 nm per meter of altitude change and increases as the square of the aperture diameter. The vertical velocity of the sodium centroid altitude is found to be ~23 ms(-1) on a 1 s time scale. If these high-frequency fluctuations arise primarily from advection of horizontal structure by the mesospheric wind, our data imply that variations in the sodium centroid altitude on the order of tens of meters occur over the horizontal scales spanned by proposed laser guide star asterisms. This leads to substantial differential focus errors (~107 nm over a 1 arc min separation with a 30 m aperture diameter) that may impact the performance of wide-field adaptive optics systems. Short-lasting and narrow sodium density enhancements, more than 1 order of magnitude above the local sodium density, occur due to advection of meteor trails. These have the ability to change the sodium centroid altitude by as much as 1 km in less than 1 s, which could result in temporary disruption of adaptive optics systems.

  8. Analysis of slide exploration strategy of cytologists when reading digital slides

    NASA Astrophysics Data System (ADS)

    Pantanowitz, Liron; Parwani, Anil; Tseytlin, Eugene; Mello-Thoms, Claudia

    2012-02-01

    Cytology is the sub-domain of Pathology that deals mainly with the diagnosis of cellular changes caused by disease. Current clinical practice involves a cytotechnologist that manually screens glass slides containing fixed cytology material using a light microscope. Screened slides are then forwarded to a specialized pathologist, a cytopathologist, for microscopic review and final diagnostic interpretation. If no abnormalities are detected, the specimen is interpreted as "normal", otherwise the abnormalities are marked with a pen on the glass slide by the cytotechnologist and then are used to render a diagnosis. As Pathology is migrating towards a digital environment it is important to determine whether these crucial screening and diagnostic tasks can be performed as well using digital slides as the current practice with glass slides. The purpose of this work is to make this assessment, by using a set of digital slides depicting cytological materials of different disease processes in several organs, and then to analyze how different cytologists including cytotechnologists, cytopathologists and cytotechnology-trainees explored the digital slides. We will (1) collect visual search data from the cytologists as they navigate the digital slides, as well as record any electronic marks (annotations) made by the cytologists; (2) convert the dynamic visual search data into a static representation of the observers' exploration strategy using 'search maps'; and (3) determine slide coverage, per viewing magnification range, for each group. We have developed a virtual microscope to collect this data, and this interface allows for interactive navigation of the virtual slide (including panning and zooming), as well as annotation of reportable findings. Furthermore, all interactions with the interface are time stamped, which allows us to recreate the cytologists' search strategy.

  9. Adaptive intermittent control: A computational model explaining motor intermittency observed in human behavior.

    PubMed

    Sakaguchi, Yutaka; Tanaka, Masato; Inoue, Yasuyuki

    2015-07-01

    It is a fundamental question how our brain performs a given motor task in a real-time fashion with the slow sensorimotor system. Computational theory proposed an influential idea of feed-forward control, but it has mainly treated the case that the movement is ballistic (such as reaching) because the motor commands should be calculated in advance of movement execution. As a possible mechanism for operating feed-forward control in continuous motor tasks (such as target tracking), we propose a control model called "adaptive intermittent control" or "segmented control," that brain adaptively divides the continuous time axis into discrete segments and executes feed-forward control in each segment. The idea of intermittent control has been proposed in the fields of control theory, biological modeling and nonlinear dynamical system. Compared with these previous models, the key of the proposed model is that the system speculatively determines the segmentation based on the future prediction and its uncertainty. The result of computer simulation showed that the proposed model realized faithful visuo-manual tracking with realistic sensorimotor delays and with less computational costs (i.e., with fewer number of segments). Furthermore, it replicated "motor intermittency", that is, intermittent discontinuities commonly observed in human movement trajectories. We discuss that the temporally segmented control is an inevitable strategy for brain which has to achieve a given task with small computational (or cognitive) cost, using a slow control system in an uncertain variable environment, and the motor intermittency is the side-effect of this strategy.

  10. Optimization and vibration suppression of adaptive composite panels using genetic algorithm and disturbance observer technique

    NASA Astrophysics Data System (ADS)

    Yan, Su; Ghasemi-Nejhad, Mehrdad N.

    2003-07-01

    In this paper, a model of the adaptive composite panel surfaces with piezoelectric patches is built using the Rayleigh-Ritz method based on the laminate theory. The interia and stiffness of the actuators are considered in the developed model. An optimal actuator location has been proved to be desirable since the piezoelectric actuators often have limitations of delivering large power oiutputs. Due to its effectiveness in seraching optimal design parameters and obtaining globally optimal solutions, the genetic algorithm has been applied to find optimal locations of piezoelectric actuators for the vibration control of a smart composite beam. In addition, the effects of population size, the crossover probability, and the mutation probability on the convergence of the genetic algorithm are investigated. Meanwhile, linear quadric regulator (LQR) and disturbance observer (DOB) are employed for the vibration suppression of the optimized adaptive composite beam (ACB). The experimental results show the robustness of the DOB, which can successfully suppress the vibrations of the cantilevered ACB according to the optimization results in an uncertain system.

  11. Baseball and softball sliding injuries. Incidence, and the effect of technique in collegiate baseball and softball players.

    PubMed

    Hosey, R G; Puffer, J C

    2000-01-01

    We prospectively observed seven softball and three baseball Division I collegiate teams to study the incidence of sliding injuries, the types of injuries resulting from the sliding technique, and the amount of time lost from participation. Slides were categorized as either feet- or head-first on the basis of the leading part of the body during the slide. Slides were further stratified depending on whether a diveback technique was performed. We recorded 37 injuries in 3889 slides in 637 games and 7596 athlete game exposures. The overall incidence of sliding injuries was 9.51 per 1000 slides and 4.87 per 1000 game exposures. Softball players had a significantly higher incidence of sliding injuries (12.13 per 1000 slides) than did baseball players (6.01 per 1000 slides). In baseball, the injury rate was higher for feet-first slides (7.31 per 1000 slides) than for headfirst slides (3.53 per 1000 slides) or divebacks (5.75 per 1000 divebacks). In softball, injury rates were higher for head-first slides (19.46 per 1000 slides) than for feet-first slides (10.04 per 1000 slides) or divebacks (7.49 per 1000 divebacks). The majority of injuries sustained were minor, with only four (11%) injuries causing the athlete to miss more than 7 days of participation.

  12. Numerical Modelling of Tsunami Generated by Deformable Submarine Slides: Parameterisation of Slide Dynamics for Coupling to Tsunami Propagation Model

    NASA Astrophysics Data System (ADS)

    Smith, R. C.; Collins, G. S.; Hill, J.; Piggott, M. D.; Mouradian, S. L.

    2015-12-01

    Numerical modelling informs risk assessment of tsunami generated by submarine slides; however, for large-scale slides modelling can be complex and computationally challenging. Many previous numerical studies have approximated slides as rigid blocks that moved according to prescribed motion. However, wave characteristics are strongly dependent on the motion of the slide and previous work has recommended that more accurate representation of slide dynamics is needed. We have used the finite-element, adaptive-mesh CFD model Fluidity, to perform multi-material simulations of deformable submarine slide-generated waves at real world scales for a 2D scenario in the Gulf of Mexico. Our high-resolution approach represents slide dynamics with good accuracy, compared to other numerical simulations of this scenario, but precludes tracking of wave propagation over large distances. To enable efficient modelling of further propagation of the waves, we investigate an approach to extract information about the slide evolution from our multi-material simulations in order to drive a single-layer wave propagation model, also using Fluidity, which is much less computationally expensive. The extracted submarine slide geometry and position as a function of time are parameterised using simple polynomial functions. The polynomial functions are used to inform a prescribed velocity boundary condition in a single-layer simulation, mimicking the effect the submarine slide motion has on the water column. The approach is verified by successful comparison of wave generation in the single-layer model with that recorded in the multi-material, multi-layer simulations. We then extend this approach to 3D for further validation of this methodology (using the Gulf of Mexico scenario proposed by Horrillo et al., 2013) and to consider the effect of lateral spreading. This methodology is then used to simulate a series of hypothetical submarine slide events in the Arctic Ocean (based on evidence of historic

  13. Ecological Change, Sliding Baselines and the Importance of Historical Data: Lessons from Combing Observational and Quantitative Data on a Temperate Reef Over 70 Years

    PubMed Central

    Gatti, Giulia; Bianchi, Carlo Nike; Parravicini, Valeriano; Rovere, Alessio; Peirano, Andrea; Montefalcone, Monica; Massa, Francesco; Morri, Carla

    2015-01-01

    Understanding the effects of environmental change on ecosystems requires the identification of baselines that may act as reference conditions. However, the continuous change of these references challenges our ability to define the true natural status of ecosystems. The so-called sliding baseline syndrome can be overcome through the analysis of quantitative time series, which are, however, extremely rare. Here we show how combining historical quantitative data with descriptive ‘naturalistic’ information arranged in a chronological chain allows highlighting long-term trends and can be used to inform present conservation schemes. We analysed the long-term change of a coralligenous reef, a marine habitat endemic to the Mediterranean Sea. The coralligenous assemblages of Mesco Reef (Ligurian Sea, NW Mediterranean) have been studied, although discontinuously, since 1937 thus making available both detailed descriptive information and scanty quantitative data: while the former was useful to understand the natural history of the ecosystem, the analysis of the latter was of paramount importance to provide a formal measure of change over time. Epibenthic assemblages remained comparatively stable until the 1990s, when species replacement, invasion by alien algae, and biotic homogenisation occurred within few years, leading to a new and completely different ecosystem state. The shift experienced by the coralligenous assemblages of Mesco Reef was probably induced by a combination of seawater warming and local human pressures, the latter mainly resulting in increased water turbidity; in turn, cumulative stress may have favoured the establishment of alien species. This study showed that the combined analysis of quantitative and descriptive historical data represent a precious knowledge to understand ecosystem trends over time and provide help to identify baselines for ecological management. PMID:25714413

  14. Ecological change, sliding baselines and the importance of historical data: lessons from Combining [corrected] observational and quantitative data on a temperate reef over 70 years.

    PubMed

    Gatti, Giulia; Bianchi, Carlo Nike; Parravicini, Valeriano; Rovere, Alessio; Peirano, Andrea; Montefalcone, Monica; Massa, Francesco; Morri, Carla

    2015-01-01

    Understanding the effects of environmental change on ecosystems requires the identification of baselines that may act as reference conditions. However, the continuous change of these references challenges our ability to define the true natural status of ecosystems. The so-called sliding baseline syndrome can be overcome through the analysis of quantitative time series, which are, however, extremely rare. Here we show how combining historical quantitative data with descriptive 'naturalistic' information arranged in a chronological chain allows highlighting long-term trends and can be used to inform present conservation schemes. We analysed the long-term change of a coralligenous reef, a marine habitat endemic to the Mediterranean Sea. The coralligenous assemblages of Mesco Reef (Ligurian Sea, NW Mediterranean) have been studied, although discontinuously, since 1937 thus making available both detailed descriptive information and scanty quantitative data: while the former was useful to understand the natural history of the ecosystem, the analysis of the latter was of paramount importance to provide a formal measure of change over time. Epibenthic assemblages remained comparatively stable until the 1990s, when species replacement, invasion by alien algae, and biotic homogenisation occurred within few years, leading to a new and completely different ecosystem state. The shift experienced by the coralligenous assemblages of Mesco Reef was probably induced by a combination of seawater warming and local human pressures, the latter mainly resulting in increased water turbidity; in turn, cumulative stress may have favoured the establishment of alien species. This study showed that the combined analysis of quantitative and descriptive historical data represent a precious knowledge to understand ecosystem trends over time and provide help to identify baselines for ecological management. PMID:25714413

  15. Observations of Rosetta Target (21) Lutetia with Keck and Gemini Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Conrad, A. R.; Merline, W. J.; Drummond, J.; Carry, B.; Tamblyn, P. M.; Chapman, C. R.; Dumas, C.; Weaver, H. A.

    2009-12-01

    In support of the NASA/ESA Rosetta mission’s plans to observe asteroid (21) Lutetia during a 2010 July flyby, and in conjunction with a larger ground-based plus HST campaign to support this mission, we observed Lutetia from Keck and Gemini-North during several nights spanning 2008 Oct through 2009 Jan. Observations were made using adaptive optics in the near-IR, primarily at K-band (2.1 micron), and were timed to coincide with the asteroid's most recent opposition at a distance of about 1.4 AU. From these data, we determined Lutetia’s triaxial size and shape to be 132 x 101 x 76 km, with maximum expected uncertainties of 4 x 3 x 31 km. The spin pole is found to be at (RA, Dec) = (48, +9) deg or ecliptic (long, lat) = (49,-8) deg, with a formal uncertainty radius (not including systematics) of 3 deg. We have calibrated our technique of deriving dimensions of asteroids from AO images against Pluto and 4 satellites of Saturn with accurate diameters, and we expect that our systematics (included in the size uncertainties above) are no more than 3%. We also searched for satellites and our preliminary results indicate no detection of a satellite larger than about 1 km over a significant fraction of the Hill sphere (10-240 asteroid radii). Improved limits are expected from a more refined analysis. We are grateful for telescope time made available to us by S. Kulkarni and M. Busch (Cal Tech) for a portion of this dataset. We also thank our collaborators on Team Keck, the Keck science staff, for making possible some of these observations and for observing time granted at Gemini under NOAO time allocation. Plane-of-sky short and long axes of (21) Lutetia taken from Keck AO images on 2008 Dec 2.

  16. Adaptive intermittent control: A computational model explaining motor intermittency observed in human behavior.

    PubMed

    Sakaguchi, Yutaka; Tanaka, Masato; Inoue, Yasuyuki

    2015-07-01

    It is a fundamental question how our brain performs a given motor task in a real-time fashion with the slow sensorimotor system. Computational theory proposed an influential idea of feed-forward control, but it has mainly treated the case that the movement is ballistic (such as reaching) because the motor commands should be calculated in advance of movement execution. As a possible mechanism for operating feed-forward control in continuous motor tasks (such as target tracking), we propose a control model called "adaptive intermittent control" or "segmented control," that brain adaptively divides the continuous time axis into discrete segments and executes feed-forward control in each segment. The idea of intermittent control has been proposed in the fields of control theory, biological modeling and nonlinear dynamical system. Compared with these previous models, the key of the proposed model is that the system speculatively determines the segmentation based on the future prediction and its uncertainty. The result of computer simulation showed that the proposed model realized faithful visuo-manual tracking with realistic sensorimotor delays and with less computational costs (i.e., with fewer number of segments). Furthermore, it replicated "motor intermittency", that is, intermittent discontinuities commonly observed in human movement trajectories. We discuss that the temporally segmented control is an inevitable strategy for brain which has to achieve a given task with small computational (or cognitive) cost, using a slow control system in an uncertain variable environment, and the motor intermittency is the side-effect of this strategy. PMID:25897510

  17. The Core of NGC 6240 from Keck Adaptive Optics and HST NICMOS Observations

    SciTech Connect

    Max, C E; Canalizo, G; Macintosh, B A; Raschke, L; Whysong, D; Antonucci, R; Schneider, G

    2004-11-19

    We present results of near infrared imaging of the disk-galaxy-merger NGC 6240 using adaptive optics on the Keck II Telescope and reprocessed archival data from NICMOS on the Hubble Space Telescope. Both the North and South nuclei of NGC 6240 are clearly elongated, with considerable sub-structure within each nucleus. In K' band there are at least two point-sources within the North nucleus; we tentatively identify the south-western point-source within the North nucleus as the position of one of the two AGNs. Within the South nucleus, the northern subnucleus is more highly reddened. Based upon the nuclear separation measured at 5 GHz, we suggest that the AGN in the South nucleus is still enshrouded in dust at K' band, and is located slightly to the north of the brightest point in K' band. Within the South nucleus there is strong H{sub 2} 1-0 S(1) line emission from the northern sub-nucleus, contrary to the conclusions of previous seeing-limited observations. Narrowband H{sub 2} emission-line images show that a streamer or ribbon of excited molecular hydrogen connects the North and South nuclei. We suggest that this linear feature corresponds to a bridge of gas connecting the two nuclei, as seen in computer simulations of mergers. Many any point-like regions are seen around the two nuclei. These are most prominent at 1.1 microns with NICMOS, and in K'-band with Keck adaptive optics. We suggest that these point-sources represent young star clusters formed in the course of the merger.

  18. The Core of NGC 6240 from Keck Adaptive Optics and HST NICMOS Observations

    SciTech Connect

    Max, C E; Canalizo, G; Macintosh, B A; Raschke, L; Whysong, D; Antonucci, R; Schneider, G

    2004-06-28

    We present results of near infrared imaging of the disk-galaxy-merger NGC 6240 using adaptive optics on the Keck II Telescope and reprocessed archival data from NICMOS on the Hubble Space Telescope. Both the North and South nuclei of NGC 6240 are clearly elongated, with considerable sub-structure within each nucleus. In K' band there are at least two point-sources within the North nucleus; we tentatively identify the south-western point-source within the North nucleus as the position of one of the two AGNs. Within the South nucleus, the northern subnucleus is more highly reddened. Based upon the nuclear separation measured at 5 GHz, we suggest that the AGN in the South nucleus is still enshrouded in dust at K' band, and is located slightly to the north of the brightest point in K' band. Within the South nucleus there is strong H{sub 2} 1-0 S(1) line emission from the northern sub-nucleus, contrary to the conclusions of previous seeing-limited observations. Narrowband H{sub 2} emission-line images show that a streamer or ribbon of excited molecular hydrogen connects the North and South nuclei. We suggest that this linear feature corresponds to a bridge of gas connecting the two nuclei, as seen in computer simulations of mergers. Many point-like regions are seen around the two nuclei. These are most prominent at 1.1 microns with NICMOS, and in K'-band with Keck adaptive optics. We suggest that these point-sources represent star clusters formed in the course of the merger.

  19. Influence of normal loads and sliding velocities on friction properties of engineering plastics sliding against rough counterfaces

    NASA Astrophysics Data System (ADS)

    Nuruzzaman, D. M.; Chowdhury, M. A.; Rahaman, M. L.; Oumer, A. N.

    2016-02-01

    Friction properties of plastic materials are very important under dry sliding contact conditions for bearing applications. In the present research, friction properties of engineering plastics such as polytetrafluoroethylene (PTFE) and nylon are investigated under dry sliding contact conditions. In the experiments, PTFE and nylon slide against different rough counterfaces such as mild steel and stainless steel 316 (SS 316). Frictional tests are carried out at low loads 5, 7.5 and 10 N, low sliding velocities 0.5, 0.75 and 1 m/s and relative humidity 70%. The obtained results reveal that friction coefficient of PTFE increases with the increase in normal loads and sliding velocities within the observed range. On the other hand, frictional values of nylon decrease with the increase in normal loads and sliding velocities. It is observed that in general, these polymers show higher frictional values when sliding against SS 316 rather than mild steel. During running-in process, friction coefficient of PTFE and nylon steadily increases with the increase in rubbing time and after certain duration of rubbing, it remains at steady level. At identical operating conditions, the frictional values are significantly different depending on normal load, sliding velocity and material pair. It is also observed that in general, the influence of normal load on the friction properties of PTFE and nylon is greater than that of sliding velocity.

  20. Translation, cultural adaptation and content re-validation of the observational teamwork assessment for surgery tool.

    PubMed

    Amaya Arias, Ana Carolina; Barajas, Rocío; Eslava-Schmalbach, Javier H; Wheelock, Ana; Gaitán Duarte, Hernando; Hull, Louise; Sevdalis, Nick

    2014-12-01

    Background. Poor teamwork and nontechnical skill performance are increasingly recognized as important contributing factors to errors and adverse events in the operating room. Assessment of these safety critical skills is important to facilitate improvement, however there are no tools available to assess these safety skills in Latin America. This study aimed to translate, culturally adapt and content validate the Observational Teamwork Assessment for Surgery (OTAS) tool for use in Latin America. Methods. A multi-phase, multi-method study was conducted: Phase 1: translation and back-translation; Phase 2: content validity assessed via expert consensus; Phase 3: inter-rater reliability assessed via real-time observation in 98 general surgical procedures using OTAS-S. Results. The first change in OTAS-S, was to distinguish between the surgical nurses and scrub technicians (both OR team members are captured in the nursing sub-team in the original OTAS). OTAS-S consists of 168 exemplar behaviors: 60/114 identical to the exemplars listed in the original OTAS tool, 48/114 original exemplars underwent minor modifications, 13 were duplicated (to account for the additional sub-team distinguished in OTAS-S), 6 original exemplars were removed, and 47 new exemplar behaviors were added. Inter-observer agreement was substantial (KW = 0.602; IC: 0.581-0.620). The calculated KW by phase, behaviors and teams were between 0.534 and 0.678. Conclusions. The study provides a content validated teamwork assessment tool for use within Colombian operating rooms and potentially Latin-American. OTAS-S can be used to assess the quality of teamwork in ORs, facilitate structured debriefing and thus improve patient safety and reduce team-related errors.

  1. Slowing the Summer Slide

    ERIC Educational Resources Information Center

    Smith, Lorna

    2012-01-01

    Research shows that summer slide--the loss of learning over the summer break--is a huge contributor to the achievement gap between low-income students and their higher-income peers. In fact, some researchers have concluded that two-thirds of the 9th-grade reading achievement gap can be explained by unequal access to summer learning opportunities…

  2. Reversing the Slide

    ERIC Educational Resources Information Center

    Gallagher, Michael

    2005-01-01

    The Government is embarking on a grand market-based vision for the sector just at the moment when university enrolments will begin a long and perhaps inexorable slide. And according to Michael Gallagher, higher education is becoming a less attractive investment for the private sector even as the Government is pushing the sector towards ever higher…

  3. Amplitude-modulated sinusoidal microchannels for observing adaptability in C. elegans locomotion

    PubMed Central

    Parashar, Archana; Lycke, Roy; Carr, John A.; Pandey, Santosh

    2011-01-01

    In this paper, we present a movement-based assay to observe adaptability in Caenorhabditis elegans locomotion behavior. The assay comprises a series of sinusoidal microchannels with a fixed wavelength and modulating (increasing or decreasing) amplitude. The channel width is comparable to the body diameter of the organism. Worms are allowed to enter the channel from the input port and migrate toward the output port. Within channel sections that closely match the worm’s natural undulations, the worm movement is relatively quick and steady. As the channel amplitude increases or decreases along the device, the worm faces difficulty in generating the propulsive thrust, begins to slow down and eventually fails to move forward. A set of locomotion parameters (i.e., average forward velocity, number and duration of stops, range of contact angle, and cut-off region) is defined for worm locomotion in modulated sinusoidal channels and extracted from the recorded videos. The device is tested on wild-type C. elegans (N2) and two mutants (lev-8 and unc-38). We anticipate this passive, movement-based assay can be used to screen nematodes showing difference in locomotion phenotype. PMID:21772935

  4. Using Copernicus earth observation services to monitor climate change impacts and adaptations

    NASA Astrophysics Data System (ADS)

    Becker, Daniel; Zebisch, Marc; Sonnenschein, Ruth; Schönthaler, Konstanze; von Andrian-Werburg, Stefan

    2016-04-01

    In the last years, earth observation made a big leap towards an operational monitoring of the state of environment. Remote sensing provides for instance information on the dynamics, trends and anomalies of snow and glaciers, vegetation, soil moisture or water temperature. In particular, the European Copernicus initiative offers new opportunities through new satellites with a higher temporal and spatial resolution, operational services for environmental monitoring and an open data access policy. With the Copernicus climate change service and the ESA climate change initiative, specific earth observation programs are in place to address the impacts of climate change. However, such products and services are until now rarely picked up in the field of policy or decision making oriented climate impact or climate risk assessments. In this talk, we will present results of a study, which focus on the question, if and how remote sensing approaches could be integrated into operational monitoring activities of climate impacts and response measures on a national and subnational scale. We assessed all existing and planned Copernicus services regarding their relevance for climate impact monitoring by comparing them against the indication fields from an indicator system for climate impact and response monitoring in Germany, which has lately been developed in the framework of the German national adaptation strategy. For several climate impact or response indicators, an immediate integration of remote sensing data could be identified and been recommended. For these cases, we will show practical examples on the benefit of remote sensing data. For other indication fields, promising approaches were found, which need further development. We argue that remote sensing is a very valuable complement to the existing indicator schemes by contributing with spatial explicit, timely information but not always easy to integrate with classical approaches, which are oriented towards consistent long

  5. Estimation of Ability Level by Using Only Observable Quantities in Adaptive Testing.

    ERIC Educational Resources Information Center

    Kirisci, Levent; Hsu, Tse-Chi

    A predictive adaptive testing (PAT) strategy was developed based on statistical predictive analysis, and its feasibility was studied by comparing PAT performance to those of the Flexilevel, Bayesian modal, and expected a posteriori (EAP) strategies in a simulated environment. The proposed adaptive test is based on the idea of using item difficulty…

  6. Optimizing weather radar observations using an adaptive multiquadric surface fitting algorithm

    NASA Astrophysics Data System (ADS)

    Martens, Brecht; Cabus, Pieter; De Jongh, Inge; Verhoest, Niko

    2013-04-01

    .e. the observed scaling factors C(xα)) on a distance aαK by introducing an offset parameter K, which results in slightly different equations to calculate a and a0. The described technique is currently being used by the Flemish Environmental Agency in an online forecasting system of river discharges within Flanders (Belgium). However, rescaling the radar data using the described algorithm is not always giving rise to an improved weather radar product. Probably one of the main reasons is the parameters K and ? which are implemented as constants. It can be expected that, among others, depending on the characteristics of the rainfall, different values for the parameters should be used. Adaptation of the parameter values is achieved by an online calibration of K and ? at each time step (every 15 minutes), using validated rain gauge measurements as ground truth. Results demonstrate that rescaling radar images using optimized values for K and ? at each time step lead to a significant improvement of the rainfall estimation, which in turn will result in higher quality discharge predictions. Moreover, it is shown that calibrated values for K and ? can be obtained in near-real time. References Cole, S. J., and Moore, R. J. (2008). Hydrological modelling using raingauge- and radar-based estimators of areal rainfall. Journal of Hydrology, 358(3-4), 159-181. Hardy, R.L., (1971) Multiquadric equations of topography and other irregular surfaces, Journal of Geophysical Research, 76(8): 1905-1915. Moore, R. J., Watson, B. C., Jones, D. A. and Black, K. B. (1989). London weather radar local calibration study. Technical report, Institute of Hydrology.

  7. Slide system for machine tools

    DOEpatents

    Douglass, Spivey S.; Green, Walter L.

    1982-01-01

    The present invention relates to a machine tool which permits the machining of nonaxisymmetric surfaces on a workpiece while rotating the workpiece about a central axis of rotation. The machine tool comprises a conventional two-slide system (X-Y) with one of these slides being provided with a relatively short travel high-speed auxiliary slide which carries the material-removing tool. The auxiliary slide is synchronized with the spindle speed and the position of the other two slides and provides a high-speed reciprocating motion required for the displacement of the cutting tool for generating a nonaxisymmetric surface at a selected location on the workpiece.

  8. Slide system for machine tools

    DOEpatents

    Douglass, S.S.; Green, W.L.

    1980-06-12

    The present invention relates to a machine tool which permits the machining of nonaxisymmetric surfaces on a workpiece while rotating the workpiece about a central axis of rotation. The machine tool comprises a conventional two-slide system (X-Y) with one of these slides being provided with a relatively short travel high-speed auxiliary slide which carries the material-removing tool. The auxiliary slide is synchronized with the spindle speed and the position of the other two slides and provides a high-speed reciprocating motion required for the displacement of the cutting tool for generating a nonaxisymmetric surface at a selected location on the workpiece.

  9. Reconstitution of flagellar sliding.

    PubMed

    Alper, Joshua; Geyer, Veikko; Mukundan, Vikram; Howard, Jonathon

    2013-01-01

    The motile structure within eukaryotic cilia and flagella is the axoneme. This structure typically consists of nine doublet microtubules arranged around a pair of singlet microtubules. The axoneme contains more than 650 different proteins that have structural, force-generating, and regulatory functions. Early studies on sea urchin sperm identified the force-generating components, the dynein motors. It was shown that dynein can slide adjacent doublet microtubules in the presence of ATP. How this sliding gives rise to the beating of the axoneme is still unknown. Reconstitution assays provide a clean system, free from cellular effects, to elucidate the underlying beating mechanisms. These assays can be used to identify the components that are both necessary and sufficient for the generation of flagellar beating. PMID:23498749

  10. Reconstitution of flagellar sliding.

    PubMed

    Alper, Joshua; Geyer, Veikko; Mukundan, Vikram; Howard, Jonathon

    2013-01-01

    The motile structure within eukaryotic cilia and flagella is the axoneme. This structure typically consists of nine doublet microtubules arranged around a pair of singlet microtubules. The axoneme contains more than 650 different proteins that have structural, force-generating, and regulatory functions. Early studies on sea urchin sperm identified the force-generating components, the dynein motors. It was shown that dynein can slide adjacent doublet microtubules in the presence of ATP. How this sliding gives rise to the beating of the axoneme is still unknown. Reconstitution assays provide a clean system, free from cellular effects, to elucidate the underlying beating mechanisms. These assays can be used to identify the components that are both necessary and sufficient for the generation of flagellar beating.

  11. Modification, translation and adaptation of questionnaires: should copyright laws be observed?

    PubMed

    Juniper, Elizabeth F

    2009-06-01

    This commentary is intended to start a discussion about whether people should be allowed to modify, translate, adapt or sell copyrighted questionnaires without the permission of the developer (copyright-holder).

  12. Analysis and Synthesis of Memory-Based Fuzzy Sliding Mode Controllers.

    PubMed

    Zhang, Jinhui; Lin, Yujuan; Feng, Gang

    2015-12-01

    This paper addresses the sliding mode control problem for a class of Takagi-Sugeno fuzzy systems with matched uncertainties. Different from the conventional memoryless sliding surface, a memory-based sliding surface is proposed which consists of not only the current state but also the delayed state. Both robust and adaptive fuzzy sliding mode controllers are designed based on the proposed memory-based sliding surface. It is shown that the sliding surface can be reached and the closed-loop control system is asymptotically stable. Furthermore, to reduce the chattering, some continuous sliding mode controllers are also presented. Finally, the ball and beam system is used to illustrate the advantages and effectiveness of the proposed approaches. It can be seen that, with the proposed control approaches, not only can the stability be guaranteed, but also its transient performance can be improved significantly.

  13. Adaptive Optics and planned HST follow-up observations of the strongly lensed SNIa iPTF16geu

    NASA Astrophysics Data System (ADS)

    Goobar, Ariel; Amanullah, Rahman; Kulkarni, Shri; Steidel, Charles; Law, David

    2016-10-01

    Adaptive optics (AO) observations of iPTF16geu (ATel #9603) were carried out on October 11 with NACO in Natural Guide Star (NGS) mode on VLT. A bright star 30" SE of the SN position provided for the AO corrections.

  14. Observation-driven adaptive differential evolution and its application to accurate and smooth bronchoscope three-dimensional motion tracking.

    PubMed

    Luo, Xiongbiao; Wan, Ying; He, Xiangjian; Mori, Kensaku

    2015-08-01

    This paper proposes an observation-driven adaptive differential evolution algorithm that fuses bronchoscopic video sequences, electromagnetic sensor measurements, and computed tomography images for accurate and smooth bronchoscope three-dimensional motion tracking. Currently an electromagnetic tracker with a position sensor fixed at the bronchoscope tip is commonly used to estimate bronchoscope movements. The large tracking error from directly using sensor measurements, which may be deteriorated heavily by patient respiratory motion and the magnetic field distortion of the tracker, limits clinical applications. How to effectively use sensor measurements for precise and stable bronchoscope electromagnetic tracking remains challenging. We here exploit an observation-driven adaptive differential evolution framework to address such a challenge and boost the tracking accuracy and smoothness. In our framework, two advantageous points are distinguished from other adaptive differential evolution methods: (1) the current observation including sensor measurements and bronchoscopic video images is used in the mutation equation and the fitness computation, respectively and (2) the mutation factor and the crossover rate are determined adaptively on the basis of the current image observation. The experimental results demonstrate that our framework provides much more accurate and smooth bronchoscope tracking than the state-of-the-art methods. Our approach reduces the tracking error from 3.96 to 2.89 mm, improves the tracking smoothness from 4.08 to 1.62 mm, and increases the visual quality from 0.707 to 0.741. PMID:25660001

  15. Microtubule sliding in reactivated flagella.

    PubMed

    Takahashi, K; Shingyoji, C; Kamimura, S

    1982-01-01

    Recent experimental studies of microtubule sliding in demembranated sea urchin sperm flagella are described. A local iontophoretic application of ATP to a Triton-extracted flagellum elicits a local bending response whose form is in exact conformity with the predictions of the sliding microtubule model. Cinematographic analysis of the microtubule sliding initiated by treating fragments of demembranated flagella with trypsin in the presence of ATP reveals that the speed of sliding is almost constant. This implies that the speed does not depend on the number of dynein arms participating in the generation of sliding force. The distribution of apparent sliding velocities indicates that there is no difference in sliding velocity among the doublets. The sliding velocity depends on MgATP concentration in a manner consistent with Michaelis-Menten kinetics. The sliding velocity of doublets in trypsin-treated axonemes is close to the maximum velocity of relative sliding taking place between adjacent doublets in beating flagella reactivated at the same MgATP concentration.

  16. Comparing approaches for numerical modelling of tsunami generation by deformable submarine slides

    NASA Astrophysics Data System (ADS)

    Smith, Rebecca C.; Hill, Jon; Collins, Gareth S.; Piggott, Matthew D.; Kramer, Stephan C.; Parkinson, Samuel D.; Wilson, Cian

    2016-04-01

    Tsunami generated by submarine slides are arguably an under-considered risk in comparison to earthquake-generated tsunami. Numerical simulations of submarine slide-generated waves can be used to identify the important factors in determining wave characteristics. Here we use Fluidity, an open source finite element code, to simulate waves generated by deformable submarine slides. Fluidity uses flexible unstructured meshes combined with adaptivity which alters the mesh topology and resolution based on the simulation state, focussing or reducing resolution, when and where it is required. Fluidity also allows a number of different numerical approaches to be taken to simulate submarine slide deformation, free-surface representation, and wave generation within the same numerical framework. In this work we use a multi-material approach, considering either two materials (slide and water with a free surface) or three materials (slide, water and air), as well as a sediment model (sediment, water and free surface) approach. In all cases the slide is treated as a viscous fluid. Our results are shown to be consistent with laboratory experiments using a deformable submarine slide, and demonstrate good agreement when compared with other numerical models. The three different approaches for simulating submarine slide dynamics and tsunami wave generation produce similar waveforms and slide deformation geometries. However, each has its own merits depending on the application. Mesh adaptivity is shown to be able to reduce the computational cost without compromising the accuracy of results.

  17. Roles of hardness in the sliding behavior of materials

    NASA Astrophysics Data System (ADS)

    Rigney, D. A.

    1994-06-01

    It is generally recognized that hardness is one of the key factors which influence the sliding behavior of different materials combinations. However, in many discussions the only hardness value considered is that of the softer of the two materials in a tribological pair. This is usually the case when a simple linear wear equation (Holm, Archard, Khruschov) is cited. Observations on many materials combinations demonstrate that the effects of hardness are much more complex. Hardness varies with position and time. It can depend on temperature, sliding speed and the chemical environment. The sign of hardness gradients adjacent to the sliding surface affects sliding behavior. Transfer and subsequent mechanical mixing strongly influence local hardness. Changes in hardness can affect transitions in friction and wear. Relative hardness values can help to explain differences in debris and in smooth and rough sliding. They can also help us to understand geometric effects such as those noted when materials are interchanged in a test system. Examples are described.

  18. Appearance Normalization of Histology Slides

    NASA Astrophysics Data System (ADS)

    Niethammer, Marc; Borland, David; Marron, J. S.; Woosley, John; Thomas, Nancy E.

    This paper presents a method for automatic color and intensity normalization of digitized histology slides stained with two different agents. In comparison to previous approaches, prior information on the stain vectors is used in the estimation process, resulting in improved stability of the estimates. Due to the prevalence of hematoxylin and eosin staining for histology slides, the proposed method has significant practical utility. In particular, it can be used as a first step to standardize appearances across slides, that is very effective at countering effects due to differing stain amounts and protocols, and to slide fading. The approach is validated using synthetic experiments and 13 real datasets.

  19. Ceramic wear in indentation and sliding

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1984-01-01

    The various wear mechanisms involved with single-crystal ceramic materials in indentation and in sliding contacts. Experiments simulating interfacial events have been conducted with hemispherical, conical and pyramidal indenters (riders). With spherical riders, under either abrasive or adhesive conditions, two types of fracture pits have been observed. First, spherical-shaped fracture pits and wear particles are found as a result of either indenting or sliding. These are shown to be due to a spherical-shaped fracture along the circular or spherical stress trajectories. Second, polyhedral fracture pits and debris, produced by anisotropic fracture, and also found both during indenting and sliding. These are primarily controlled by surface and subsurface cracking along cleavage planes. Several quantitative results have also been obtained from this work. For example, using a pyramidal diamond, crack length of Mn-Zn ferrite in the indentation process grows linearly with increasing normal load. Moreover, the critical load to fracture both in indentation and sliding is essentially isotropic and is found to be directly proportional to the indenter radius.

  20. Programmed Instruction with Microfiche: Intoduction to the Slide Rule.

    ERIC Educational Resources Information Center

    Wachtel, L. W.

    The use of microfiche as a means of programed self-instruction was examined in this study. Lessons adapted from a one-hour lecture on the slide rule were typed in large print in order to allow easy reading at distances normally used with microfiche readers. The 58 pages of the course were reproduced on microfilm, strips of which were then inserted…

  1. Using Scrap Slides for Art.

    ERIC Educational Resources Information Center

    Hanlon, Heather

    1979-01-01

    Using scrap slides for an art lesson can be an exciting, creative experience for people of all ages, and many techniques are applicable in both primary and secondary grades. Scrap slides are an inexpensive means to unique, original, and stimulating discoveries about film as an art form. (Author)

  2. Finite-time control of DC-DC buck converters via integral terminal sliding modes

    NASA Astrophysics Data System (ADS)

    Chiu, Chian-Song; Shen, Chih-Teng

    2012-05-01

    This article presents novel terminal sliding modes for finite-time output tracking control of DC-DC buck converters. Instead of using traditional singular terminal sliding mode, two integral terminal sliding modes are introduced for robust output voltage tracking of uncertain buck converters. Different from traditional sliding mode control (SMC), the proposed controller assures finite convergence time for the tracking error and integral tracking error. Furthermore, the singular problem in traditional terminal SMC is removed from this article. When considering worse modelling, adaptive integral terminal SMC is derived to guarantee finite-time convergence under more relaxed stability conditions. In addition, several experiments show better start-up performance and robustness.

  3. Appearance normalization of histology slides.

    PubMed

    Vicory, Jared; Couture, Heather D; Thomas, Nancy E; Borland, David; Marron, J S; Woosley, John; Niethammer, Marc

    2015-07-01

    This paper presents a method for automatic color and intensity normalization of digitized histology slides stained with two different agents. In comparison to previous approaches, prior information on the stain vectors is used in the plane estimation process, resulting in improved stability of the estimates. Due to the prevalence of hematoxylin and eosin staining for histology slides, the proposed method has significant practical utility. In particular, it can be used as a first step to standardize appearance across slides and is effective at countering effects due to differing stain amounts and protocols and counteracting slide fading. The approach is validated against non-prior plane-fitting using synthetic experiments and 13 real datasets. Results of application of the method to adjustment of faded slides are given, and the effectiveness of the method in aiding statistical classification is shown.

  4. Experimentally observe the effect of spherical aberration on diffractive intraocular lens using adaptive optics

    NASA Astrophysics Data System (ADS)

    Guo, Huanqing; DeLestrange, Elie

    2015-03-01

    We first investigated the similarity in optical quality of a batch of diffractive intraocular lenses (DIOLs), providing experimental evidence for one DIOL as representative of a batch. Using adaptive optics, we then evaluated one DIOL under different levels of Zernike spherical aberration (SA) by applying both a point spread function test and a psychophysical visual acuity test. We found that for small aperture size SA has the effect of shifting the through-focus curve of DIOL. Also, for a relatively large aperture size, it has different effects on the distant and near foci.

  5. Sliding-Ring Catenanes.

    PubMed

    Fernando, Isurika R; Frasconi, Marco; Wu, Yilei; Liu, Wei-Guang; Wasielewski, Michael R; Goddard, William A; Stoddart, J Fraser

    2016-08-17

    Template-directed protocols provide a routine approach to the synthesis of mechanically interlocked molecules (MIMs), in which the mechanical bonds are stabilized by a wide variety of weak interactions. In this Article, we describe a strategy for the preparation of neutral [2]catenanes with sliding interlocked electron-rich rings, starting from two degenerate donor-acceptor [2]catenanes, consisting of a tetracationic cyclobis(paraquat-p-phenylene) cyclophane (CBPQT(4+)) and crown ethers containing either (i) hydroquinone (HQ) or (ii) 1,5-dioxynaphthalene (DNP) recognition units and carrying out four-electron reductions of the cyclophane components to their neutral forms. The donor-acceptor interactions between the CBPQT(4+) ring and both HQ and DNP units present in the crown ethers that stabilize the [2]catenanes are weakened upon reduction of the cyclophane components to their radical cationic states and are all but absent in their fully reduced states. Characterization in solution performed by UV-vis, EPR, and NMR spectroscopic probes reveals that changes in the redox properties of the [2]catenanes result in a substantial decrease of the energy barriers for the circumrotation and pirouetting motions of the interlocked rings, which glide freely through one another in the neutral states. The solid-state structures of the fully reduced catenanes reveal profound changes in the relative dispositions of the interlocked rings, with the glycol chains of the crown ethers residing in the cavities of the neutral CBPQT(0) rings. Quantum mechanical investigations of the energy levels associated with the four different oxidation states of the catenanes support this interpretation. Catenanes and rotaxanes with sliding rings are expected to display unique properties. PMID:27398609

  6. Plastic deformation at surface during unlubricated sliding

    NASA Technical Reports Server (NTRS)

    Yamamoto, T.; Buckley, D. H.

    1982-01-01

    The plastic deformation and wear of 304 stainless-steel surface slid against an aluminum oxide rider were observed by using a scanning electron microscope and an optical microscope. Experiments were conducted in a vacuum of 0.000001 Pa and in an environment of 0.0005 Pa chlorine gas at 25 C. The load was 500 grams and the sliding velocity was 0.5 centimeter per second. The deformed surface layer which accumulates and develops successively is left behind the rider, and step-shaped protuberances are developed even after single pass sliding under both environmental conditions. A fully developed surface layer is gradually torn off leaving a characteristic pattern. These observations result from both adhesion and an adhesive wear mechanism.

  7. Chaos control of the micro-electro-mechanical resonator by using adaptive dynamic surface technology with extended state observer

    NASA Astrophysics Data System (ADS)

    Luo, Shaohua; Sun, Quanping; Cheng, Wei

    2016-04-01

    This paper addresses chaos control of the micro-electro- mechanical resonator by using adaptive dynamic surface technology with extended state observer. To reveal the mechanism of the micro- electro-mechanical resonator, the phase diagrams and corresponding time histories are given to research the nonlinear dynamics and chaotic behavior, and Homoclinic and heteroclinic chaos which relate closely with the appearance of chaos are presented based on the potential function. To eliminate the effect of chaos, an adaptive dynamic surface control scheme with extended state observer is designed to convert random motion into regular motion without precise system model parameters and measured variables. Putting tracking differentiator into chaos controller solves the `explosion of complexity' of backstepping and poor precision of the first-order filters. Meanwhile, to obtain high performance, a neural network with adaptive law is employed to approximate unknown nonlinear function in the process of controller design. The boundedness of all the signals of the closed-loop system is proved in theoretical analysis. Finally, numerical simulations are executed and extensive results illustrate effectiveness and robustness of the proposed scheme.

  8. T-Slide Linear Actuators

    NASA Technical Reports Server (NTRS)

    Vranish, John

    2009-01-01

    T-slide linear actuators use gear bearing differential epicyclical transmissions (GBDETs) to directly drive a linear rack, which, in turn, performs the actuation. Conventional systems use a rotary power source in conjunction with a nut and screw to provide linear motion. Non-back-drive properties of GBDETs make the new actuator more direct and simpler. Versions of this approach will serve as a long-stroke, ultra-precision, position actuator for NASA science instruments, and as a rugged, linear actuator for NASA deployment duties. The T slide can operate effectively in the presence of side forces and torques. Versions of the actuator can perform ultra-precision positioning. A basic T-slide actuator is a long-stroke, rack-and-pinion linear actuator that, typically, consists of a T-slide, several idlers, a transmission to drive the slide (powered by an electric motor) and a housing that holds the entire assembly. The actuator is driven by gear action on its top surface, and is guided and constrained by gear-bearing idlers on its other two parallel surfaces. The geometry, implemented with gear-bearing technology, is particularly effective. An electronic motor operating through a GBDET can directly drive the T slide against large loads, as a rack and pinion linear actuator, with no break and no danger of back driving. The actuator drives the slide into position and stops. The slide holes position with power off and no brake, regardless of load. With the T slide configuration, this GBDET has an entire T-gear surface on which to operate. The GB idlers coupling the other two T slide parallel surfaces to their housing counterpart surfaces provide constraints in five degrees-of-freedom and rolling friction in the direction of actuation. Multiple GB idlers provide roller bearing strength sufficient to support efficient, rolling friction movement, even in the presence of large, resisting forces. T-slide actuators can be controlled using the combination of an off

  9. Translation, adaptation, and validation of the behavioral pain scale and the critical-care pain observational tools in Taiwan

    PubMed Central

    Hsiung, Nai-Huan; Yang, Yen; Lee, Ming Shinn; Dalal, Koustuv; Smith, Graeme D

    2016-01-01

    This study describes the cultural adaptation and testing of the behavioral pain scale (BPS) and the critical-care pain observation tools (CPOT) for pain assessment in Taiwan. The cross-cultural adaptation followed the steps of translation, including forward translation, back-translation, evaluation of the translations by a committee of experts, adjustments, and then piloting of the prefinal versions of the BPS and the CPOT. A content validity index was used to assess content validities of the BPS and the CPOT, with 0.80 preset as the level that would be regarded as acceptable. The principal investigator then made adjustments when the content validity index was <0.80. The pilot test was performed with a sample of ten purposively selected patients by 2 medical staff from a medical care center in Taiwan. The BPS and the CPOT are adequate instruments for the assessment of pain levels in patients who cannot communicate due to sedation and ventilation treatments.

  10. Translation, adaptation, and validation of the behavioral pain scale and the critical-care pain observational tools in Taiwan

    PubMed Central

    Hsiung, Nai-Huan; Yang, Yen; Lee, Ming Shinn; Dalal, Koustuv; Smith, Graeme D

    2016-01-01

    This study describes the cultural adaptation and testing of the behavioral pain scale (BPS) and the critical-care pain observation tools (CPOT) for pain assessment in Taiwan. The cross-cultural adaptation followed the steps of translation, including forward translation, back-translation, evaluation of the translations by a committee of experts, adjustments, and then piloting of the prefinal versions of the BPS and the CPOT. A content validity index was used to assess content validities of the BPS and the CPOT, with 0.80 preset as the level that would be regarded as acceptable. The principal investigator then made adjustments when the content validity index was <0.80. The pilot test was performed with a sample of ten purposively selected patients by 2 medical staff from a medical care center in Taiwan. The BPS and the CPOT are adequate instruments for the assessment of pain levels in patients who cannot communicate due to sedation and ventilation treatments. PMID:27695360

  11. Automated detection of diagnostically relevant regions in H&E stained digital pathology slides

    NASA Astrophysics Data System (ADS)

    Bahlmann, Claus; Patel, Amar; Johnson, Jeffrey; Ni, Jie; Chekkoury, Andrei; Khurd, Parmeshwar; Kamen, Ali; Grady, Leo; Krupinski, Elizabeth; Graham, Anna; Weinstein, Ronald

    2012-03-01

    We present a computationally efficient method for analyzing H&E stained digital pathology slides with the objective of discriminating diagnostically relevant vs. irrelevant regions. Such technology is useful for several applications: (1) It can speed up computer aided diagnosis (CAD) for histopathology based cancer detection and grading by an order of magnitude through a triage-like preprocessing and pruning. (2) It can improve the response time for an interactive digital pathology workstation (which is usually dealing with several GByte digital pathology slides), e.g., through controlling adaptive compression or prioritization algorithms. (3) It can support the detection and grading workflow for expert pathologists in a semi-automated diagnosis, hereby increasing throughput and accuracy. At the core of the presented method is the statistical characterization of tissue components that are indicative for the pathologist's decision about malignancy vs. benignity, such as, nuclei, tubules, cytoplasm, etc. In order to allow for effective yet computationally efficient processing, we propose visual descriptors that capture the distribution of color intensities observed for nuclei and cytoplasm. Discrimination between statistics of relevant vs. irrelevant regions is learned from annotated data, and inference is performed via linear classification. We validate the proposed method both qualitatively and quantitatively. Experiments show a cross validation error rate of 1.4%. We further show that the proposed method can prune ~90% of the area of pathological slides while maintaining 100% of all relevant information, which allows for a speedup of a factor of 10 for CAD systems.

  12. Adapting to an Uncertain World: Cognitive Capacity and Causal Reasoning with Ambiguous Observations

    PubMed Central

    Shou, Yiyun; Smithson, Michael

    2015-01-01

    Ambiguous causal evidence in which the covariance of the cause and effect is partially known is pervasive in real life situations. Little is known about how people reason about causal associations with ambiguous information and the underlying cognitive mechanisms. This paper presents three experiments exploring the cognitive mechanisms of causal reasoning with ambiguous observations. Results revealed that the influence of ambiguous observations manifested by missing information on causal reasoning depended on the availability of cognitive resources, suggesting that processing ambiguous information may involve deliberative cognitive processes. Experiment 1 demonstrated that subjects did not ignore the ambiguous observations in causal reasoning. They also had a general tendency to treat the ambiguous observations as negative evidence against the causal association. Experiment 2 and Experiment 3 included a causal learning task requiring a high cognitive demand in which paired stimuli were presented to subjects sequentially. Both experiments revealed that processing ambiguous or missing observations can depend on the availability of cognitive resources. Experiment 2 suggested that the contribution of working memory capacity to the comprehensiveness of evidence retention was reduced when there were ambiguous or missing observations. Experiment 3 demonstrated that an increase in cognitive demand due to a change in the task format reduced subjects’ tendency to treat ambiguous-missing observations as negative cues. PMID:26468653

  13. Rise of the Machines: Automated Laser Guide Star Adaptive Optics Observations of Thousands of Objects with Robo-AO

    NASA Astrophysics Data System (ADS)

    Riddle, Reed L.; Baranec, C.; Law, N. M.; Tendulkar, S. P.; Ramaprakash, A. N.; Kulkarni, S. R.; Dekany, R.; Bui, K.; Burse, M.; Das, H.; Punnadi, S.; Chordia, P.

    2013-01-01

    Robo-AO is the first fully automated laser guide star adaptive optics instrument. Robo-AO has completed thousands of automated AO observations at the visible diffraction limit for several scientific programs during its first semester of science observations. These programs include: the Ultimate Binarity Survey to examine stellar binarity properties across the main sequence and beyond; a survey of 1,000 Kepler objects of interest; the multiplicity of solar type stars; and several programs for high precision astrometric observations. A new infrared camera is under development for Robo-AO, and a clone of the system is in the planning stages. This presentation will discuss the Robo-AO instrument capabilities, summarize the science programs undertaken, and discuss the future of Robo-AO.

  14. Sliding Motility in Mycobacteria

    PubMed Central

    Martínez, Asunción; Torello, Sandra; Kolter, Roberto

    1999-01-01

    Mycobacteria are nonflagellated gram-positive microorganisms. Previously thought to be nonmotile, we show here that Mycobacterium smegmatis can spread on the surface of growth medium by a sliding mechanism. M. smegmatis spreads as a monolayer of cells which are arranged in pseudofilaments by close cell-to-cell contacts, predominantly along their longitudinal axis. The monolayer moves away from the inoculation point as a unit with only minor rearrangements. No extracellular structures such as pili or fimbriae appear to be involved in this process. The ability to translocate over the surface correlates with the presence of glycopeptidolipids, a mycobacterium-specific class of amphiphilic molecules located in the outermost layer of the cell envelope. We present evidence that surface motility is not restricted to M. smegmatis but is also a property of the slow-growing opportunistic pathogen M. avium. This form of motility could play an important role in surface colonization by mycobacteria in the environment as well as in the host. PMID:10572138

  15. Sliding friction on wet and dry sand.

    PubMed

    Fall, A; Weber, B; Pakpour, M; Lenoir, N; Shahidzadeh, N; Fiscina, J; Wagner, C; Bonn, D

    2014-05-01

    We show experimentally that the sliding friction on sand is greatly reduced by the addition of some-but not too much-water. The formation of capillary water bridges increases the shear modulus of the sand, which facilitates the sliding. Too much water, on the other hand, makes the capillary bridges coalesce, resulting in a decrease of the modulus; in this case, we observe that the friction coefficient increases again. Our results, therefore, show that the friction coefficient is directly related to the shear modulus; this has important repercussions for the transport of granular materials. In addition, the polydispersity of the sand is shown to also have a large effect on the friction coefficient. PMID:24836256

  16. Results of Instrument Observations and Adaptive Prediction of Thermoabrasion of Banks of the Vilyui Reservoir

    SciTech Connect

    Velikin, S. A.; Sobol', I. S.; Sobol', S. V.; Khokhlov, D. N.

    2013-11-15

    Quantitative data derived from observations of reformation of the thermoabrasive banks of the Viliyui Reservoir in Yakutia during the service period from 1972 through 2011, and results of analytical prediction of bank formations over the next 20 years for purposes of monitoring the ecological safety of this water body are presented.

  17. Circumnuclear Star Clusters in the Galaxy Merger NGC 6240, Observed with Keck Adaptive Optics and HST

    SciTech Connect

    Pollack, L K; Max, C E; Schneider, G

    2007-02-12

    We discuss images of the central {approx} 10 kpc (in projection) of the galaxy merger NGC 6240 at H and K{prime} bands, taken with the NIRC2 narrow camera on Keck II using natural guide star adaptive optics. We detect 28 star clusters in the NIRC2 images, of which only 7 can be seen in the similar-spatial-resolution, archival WFPC2 Planetary Camera data at either B or I bands. Combining the NIRC2 narrow camera pointings with wider NICMOS NIC2 images taken with the F110W, F160W, and F222M filters, we identify a total of 32 clusters that are detected in at least one of these 5 infrared ({lambda}{sub c} > 1 {micro}m) bandpasses. By comparing to instantaneous burst, stellar population synthesis models (Bruzual & Charlot 2003), we estimate that most of the clusters are consistent with being {approx} 15 Myr old and have photometric masses ranging from 7 x 10{sup 5} M{sub {circle_dot}} to 4 x 10{sup 7}M{sub {circle_dot}}. The total contribution to the star formation rate (SFR) from these clusters is approximately 10M{sub {circle_dot}} yr{sup -1}, or {approx} 10% of the total SFR in the nuclear region. We use these newly discovered clusters to estimate the extinction toward NGC 6240's double nuclei, and find values of A{sub v} as high as 14 magnitudes along some sightlines, with an average extinction of A{sub v} {approx} 7 mag toward sightlines within {approx} 3-inches of the double nuclei.

  18. Adaptive Optics at Optical Wavelengths: Test Observations of Kyoto 3DII Connected to Subaru Telescope AO188

    NASA Astrophysics Data System (ADS)

    Matsubayashi, K.; Sugai, H.; Shimono, A.; Akita, A.; Hattori, T.; Hayano, Y.; Minowa, Y.; Takeyama, N.

    2016-09-01

    Adaptive optics (AO) enables us to observe objects with high spatial resolution, which is important in most astrophysical observations. Most AO systems are operational at near-infrared wavelengths but not in the optical range, because optical observations require a much higher performance to obtain the same Strehl ratio as near-infrared observations. Therefore, to enable AO-assisted observations at optical wavelengths, we connected the Kyoto Tridimensional Spectrograph II (Kyoto 3DII), which can perform integral field spectroscopy, to the second generation AO system of the Subaru Telescope (AO188). We developed a new beam-splitter that reflects light below 594 nm for the wavefront sensors of AO188 and transmits above 644 nm for Kyoto 3DII. We also developed a Kyoto 3DII mount at the Nasmyth focus of the Subaru Telescope. In test observations, the spatial resolution of the combined AO188-Kyoto 3DII was higher than that in natural seeing conditions, even at 6500 Å. The full width at half maximum of an undersampled (1.5 spaxels) bright guide star (7.0 mag in the V-band) was 0.″12.

  19. Adaptive Optics at Optical Wavelengths: Test Observations of Kyoto 3DII Connected to Subaru Telescope AO188

    NASA Astrophysics Data System (ADS)

    Matsubayashi, K.; Sugai, H.; Shimono, A.; Akita, A.; Hattori, T.; Hayano, Y.; Minowa, Y.; Takeyama, N.

    2016-09-01

    Adaptive optics (AO) enables us to observe objects with high spatial resolution, which is important in most astrophysical observations. Most AO systems are operational at near-infrared wavelengths but not in the optical range, because optical observations require a much higher performance to obtain the same Strehl ratio as near-infrared observations. Therefore, to enable AO-assisted observations at optical wavelengths, we connected the Kyoto Tridimensional Spectrograph II (Kyoto 3DII), which can perform integral field spectroscopy, to the second generation AO system of the Subaru Telescope (AO188). We developed a new beam-splitter that reflects light below 594 nm for the wavefront sensors of AO188 and transmits above 644 nm for Kyoto 3DII. We also developed a Kyoto 3DII mount at the Nasmyth focus of the Subaru Telescope. In test observations, the spatial resolution of the combined AO188–Kyoto 3DII was higher than that in natural seeing conditions, even at 6500 Å. The full width at half maximum of an undersampled (1.5 spaxels) bright guide star (7.0 mag in the V-band) was 0.″12.

  20. Development of the Client Observation Checklist: Reliability, Validity, and Differences between Facilities Chosen To Receive Project ADAPT. Progress Report No. 32.

    ERIC Educational Resources Information Center

    Fitz, Don

    The Client Observation Checklist (COC) was developed to evaluate Project ADAPT's intervention in three behavioral areas: bathing; dressing; and socialization. Project ADAPT is designed to provide services to meet the needs of chronically mentally ill residents of nursing homes. Specifically, the project provides staff trained to work with the…

  1. Jupiter System Observer

    NASA Technical Reports Server (NTRS)

    Senske, Dave; Kwok, Johnny

    2008-01-01

    This slide presentation reviews the proposed mission for the Jupiter System Observer. The presentation also includes overviews of the mission timeline, science goals, and spacecraftspecifications for the satellite.

  2. Reinforcement learning for partially observable dynamic processes: adaptive dynamic programming using measured output data.

    PubMed

    Lewis, F L; Vamvoudakis, Kyriakos G

    2011-02-01

    Approximate dynamic programming (ADP) is a class of reinforcement learning methods that have shown their importance in a variety of applications, including feedback control of dynamical systems. ADP generally requires full information about the system internal states, which is usually not available in practical situations. In this paper, we show how to implement ADP methods using only measured input/output data from the system. Linear dynamical systems with deterministic behavior are considered herein, which are systems of great interest in the control system community. In control system theory, these types of methods are referred to as output feedback (OPFB). The stochastic equivalent of the systems dealt with in this paper is a class of partially observable Markov decision processes. We develop both policy iteration and value iteration algorithms that converge to an optimal controller that requires only OPFB. It is shown that, similar to Q -learning, the new methods have the important advantage that knowledge of the system dynamics is not needed for the implementation of these learning algorithms or for the OPFB control. Only the order of the system, as well as an upper bound on its "observability index," must be known. The learned OPFB controller is in the form of a polynomial autoregressive moving-average controller that has equivalent performance with the optimal state variable feedback gain.

  3. Designing for Damage: Robust Flight Control Design using Sliding Mode Techniques

    NASA Technical Reports Server (NTRS)

    Vetter, T. K.; Wells, S. R.; Hess, Ronald A.; Bacon, Barton (Technical Monitor); Davidson, John (Technical Monitor)

    2002-01-01

    A brief review of sliding model control is undertaken, with particular emphasis upon the effects of neglected parasitic dynamics. Sliding model control design is interpreted in the frequency domain. The inclusion of asymptotic observers and control 'hedging' is shown to reduce the effects of neglected parasitic dynamics. An investigation into the application of observer-based sliding mode control to the robust longitudinal control of a highly unstable is described. The sliding mode controller is shown to exhibit stability and performance robustness superior to that of a classical loop-shaped design when significant changes in vehicle and actuator dynamics are employed to model airframe damage.

  4. Mirror neurons in monkey area F5 do not adapt to the observation of repeated actions.

    PubMed

    Caggiano, Vittorio; Pomper, Joern K; Fleischer, Falk; Fogassi, Leonardo; Giese, Martin; Thier, Peter

    2013-01-01

    Repetitive presentation of the same visual stimulus entails a response decrease in the action potential discharge of neurons in various areas of the monkey visual cortex. It is still unclear whether this repetition suppression effect is also present in single neurons in cortical premotor areas responding to visual stimuli, as suggested by the human functional magnetic resonance imaging literature. Here we report the responses of 'mirror neurons' in monkey area F5 to the repeated presentation of action movies. We find that most single neurons and the population at large do not show a significant decrease of the firing rate. On the other hand, simultaneously recorded local field potentials exhibit repetition suppression. As local field potentials are believed to be better linked to the blood-oxygen-level-dependent (BOLD) signal exploited by functional magnetic resonance imaging, these findings suggest caution when trying to derive conclusions on the spiking activity of neurons in a given area based on the observation of BOLD repetition suppression.

  5. Soliton dynamics in a solid lubricant during sliding friction

    NASA Astrophysics Data System (ADS)

    Vigentini, Anna; Van Hattem, Barbara; Diato, Elena; Ponzellini, Paolo; Meledina, Tommaso; Vanossi, Andrea; Santoro, Giuseppe; Tosatti, Erio; Manini, Nicola

    2014-03-01

    Recent highly idealized model studies of lubricated nanofriction for two crystalline sliding surfaces with an interposed thin solid crystalline lubricant layer showed that the overall relative velocity of the lubricant vlub/vslider depends only on the ratio of the lattice spacings, and retains a strictly constant value even when system parameters are varied within a wide range. This peculiar "quantized" dynamical locking was understood as due to the sliding-induced motion of misfit dislocations, or soliton structures. So far the practical relevance of this concept to realistic sliding three-dimensional crystals has not been demonstrated. In this work, by means of classical molecular dynamics simulations and theoretical considerations, we realize a realistic three-dimensional crystal-lubricant-crystal geometry. Results show that the flux of lubricant particles associated with the advancing soliton lines gives rise here too to a quantized-velocity ratio. Moreover, depending on the interface lattice spacing mismatch, both forward and backward quantized motion of the lubricant is predicted. The persistence under realistic conditions of the dynamically pinned state and quantized sliding is further investigated by varying sliding speed, temperature, load, and lubricant film thickness. The possibilities of experimental observation of quantized sliding are also discussed.

  6. A proposed adaptive step size perturbation and observation maximum power point tracking algorithm based on photovoltaic system modeling

    NASA Astrophysics Data System (ADS)

    Huang, Yu

    Solar energy becomes one of the major alternative renewable energy options for its huge abundance and accessibility. Due to the intermittent nature, the high demand of Maximum Power Point Tracking (MPPT) techniques exists when a Photovoltaic (PV) system is used to extract energy from the sunlight. This thesis proposed an advanced Perturbation and Observation (P&O) algorithm aiming for relatively practical circumstances. Firstly, a practical PV system model is studied with determining the series and shunt resistances which are neglected in some research. Moreover, in this proposed algorithm, the duty ratio of a boost DC-DC converter is the object of the perturbation deploying input impedance conversion to achieve working voltage adjustment. Based on the control strategy, the adaptive duty ratio step size P&O algorithm is proposed with major modifications made for sharp insolation change as well as low insolation scenarios. Matlab/Simulink simulation for PV model, boost converter control strategy and various MPPT process is conducted step by step. The proposed adaptive P&O algorithm is validated by the simulation results and detail analysis of sharp insolation changes, low insolation condition and continuous insolation variation.

  7. Frequency-Shaped Sliding Mode Control for Rudder Roll Damping System of Robotic Boat

    NASA Astrophysics Data System (ADS)

    Bao, Xinping; Yu, Zhenyu; Nonami, Kenzo

    In this paper, a robotic boat model of combined yaw and roll rate is obtained by a system identification approach. The identified system is designed with frequency-shaped sliding mode control. The control scheme is composed of a sliding mode observer and a sliding mode controller. The stability and reachability of the switching function are proved by Lyapunov theory. Computer simulations and experiment carried out at INAGE offshore show that successful course keeping and roll reduction results are achieved.

  8. Design and adaptation of ocean observing systems at coastal scales, the role of data assimilation in the optimization of measures.

    NASA Astrophysics Data System (ADS)

    Brandini, Carlo; Taddei, Stefano; Fattorini, Maria; Doronzo, Bartolomeo; Lapucci, Chiara; Ortolani, Alberto; Poulain, Pierre Marie

    2015-04-01

    The design and the implementation of observation systems, in the current view, are not limited to the capability to observe some phenomena of particular interest in a given sea area, but must ensure maximum benefits to the analysis/prediction systems that are based on numerical models. The design of these experimental systems takes great advantage from the use of synthetic data, whose characteristics are as close as possible to the observed data (e.g. in-situ), in terms of spatial and temporal variability, particularly when the power spectrum of the observed signal is close to that reproduced by a numerical model. This method, usually referred to as OSSE (Observing System Simulation Experiment), is a preferred way to test numerical data for assimilation into models as if they were real data, with the advantage of defining different datasets for data assimilation at almost no cost. This applies both to the design of fixed networks (such as buoys or coastal radars), and to the improvement of the performance of mobile platforms, such as autonomous marine vehicles, floats or mobile radars, through the optimization of parameters for vehicle guidance, coverage, trajectories or localization of sampling points, according to the adaptive observation concept. In this work we present the results of some experimental activities recently undertaken in the coastal area between the Ligurian and Northern Tyrrhenian seas, that have shown a great vulnerability in recent years, due to a number of marine accidents and environmental issues. In this cross-border area an observation and forecasting system is being installed as part of the SICOMAR project (PO maritime Italy-France), in order to provide real time data at high spatial and time resolution, and to design interoperable, expandable and flexible observing platforms, that can be quickly adapted to the needs of local problems (e.g. accidents at sea). The starting SICOMAR network includes HF coastal radars, FerryBoxes onboard ships

  9. New methods for state estimation and adaptive observation of environmental flow systems leveraging coordinated swarms of sensor vehicles

    NASA Astrophysics Data System (ADS)

    Bewley, Thomas

    2015-11-01

    Accurate long-term forecasts of the path and intensity of hurricanes are imperative to protect property and save lives. Accurate estimations and forecasts of the spread of large-scale contaminant plumes, such as those from Deepwater Horizon, Fukushima, and recent volcanic eruptions in Iceland, are essential for assessing environment impact, coordinating remediation efforts, and in certain cases moving folks out of harm's way. The challenges in estimating and forecasting such systems include: (a) environmental flow modeling, (b) high-performance real-time computing, (c) assimilating measured data into numerical simulations, and (d) acquiring in-situ data, beyond what can be measured from satellites, that is maximally relevant for reducing forecast uncertainty. This talk will focus on new techniques for addressing (c) and (d), namely, data assimilation and adaptive observation, in both hurricanes and large-scale environmental plumes. In particular, we will present a new technique for the energy-efficient coordination of swarms of sensor-laden balloons for persistent, in-situ, distributed, real-time measurement of developing hurricanes, leveraging buoyancy control only (coupled with the predictable and strongly stratified flowfield within the hurricane). Animations of these results are available at http://flowcontrol.ucsd.edu/3dhurricane.mp4 and http://flowcontrol.ucsd.edu/katrina.mp4. We also will survey our unique hybridization of the venerable Ensemble Kalman and Variational approaches to large-scale data assimilation in environmental flow systems, and how essentially the dual of this hybrid approach may be used to solve the adaptive observation problem in a uniquely effective and rigorous fashion.

  10. Rate-weakening friction characterizes both slow sliding and catastrophic failure of landslides.

    PubMed

    Handwerger, Alexander L; Rempel, Alan W; Skarbek, Rob M; Roering, Joshua J; Hilley, George E

    2016-09-13

    Catastrophic landslides cause billions of dollars in damages and claim thousands of lives annually, whereas slow-moving landslides with negligible inertia dominate sediment transport on many weathered hillslopes. Surprisingly, both failure modes are displayed by nearby landslides (and individual landslides in different years) subjected to almost identical environmental conditions. Such observations have motivated the search for mechanisms that can cause slow-moving landslides to transition via runaway acceleration to catastrophic failure. A similarly diverse range of sliding behavior, including earthquakes and slow-slip events, occurs along tectonic faults. Our understanding of these phenomena has benefitted from mechanical treatments that rely upon key ingredients that are notably absent from previous landslide descriptions. Here, we describe landslide motion using a rate- and state-dependent frictional model that incorporates a nonlocal stress balance to account for the elastic response to gradients in slip. Our idealized, one-dimensional model reproduces both the displacement patterns observed in slow-moving landslides and the acceleration toward failure exhibited by catastrophic events. Catastrophic failure occurs only when the slip surface is characterized by rate-weakening friction and its lateral dimensions exceed a critical nucleation length [Formula: see text] that is shorter for higher effective stresses. However, landslides that are extensive enough to fall within this regime can nevertheless slide slowly for months or years before catastrophic failure. Our results suggest that the diversity of slip behavior observed during landslides can be described with a single model adapted from standard fault mechanics treatments.

  11. Rate-weakening friction characterizes both slow sliding and catastrophic failure of landslides.

    PubMed

    Handwerger, Alexander L; Rempel, Alan W; Skarbek, Rob M; Roering, Joshua J; Hilley, George E

    2016-09-13

    Catastrophic landslides cause billions of dollars in damages and claim thousands of lives annually, whereas slow-moving landslides with negligible inertia dominate sediment transport on many weathered hillslopes. Surprisingly, both failure modes are displayed by nearby landslides (and individual landslides in different years) subjected to almost identical environmental conditions. Such observations have motivated the search for mechanisms that can cause slow-moving landslides to transition via runaway acceleration to catastrophic failure. A similarly diverse range of sliding behavior, including earthquakes and slow-slip events, occurs along tectonic faults. Our understanding of these phenomena has benefitted from mechanical treatments that rely upon key ingredients that are notably absent from previous landslide descriptions. Here, we describe landslide motion using a rate- and state-dependent frictional model that incorporates a nonlocal stress balance to account for the elastic response to gradients in slip. Our idealized, one-dimensional model reproduces both the displacement patterns observed in slow-moving landslides and the acceleration toward failure exhibited by catastrophic events. Catastrophic failure occurs only when the slip surface is characterized by rate-weakening friction and its lateral dimensions exceed a critical nucleation length [Formula: see text] that is shorter for higher effective stresses. However, landslides that are extensive enough to fall within this regime can nevertheless slide slowly for months or years before catastrophic failure. Our results suggest that the diversity of slip behavior observed during landslides can be described with a single model adapted from standard fault mechanics treatments. PMID:27573836

  12. A novel glass slide filing system for pathology slides.

    PubMed

    Tsai, Steve; Kartono, Francisca; Shitabata, Paul K

    2007-07-01

    The availability of a collection of microscope glass slides for review is essential in the study and practice of pathology. A common problem facing many pathologists is the lack of a well-organized filing system. We present a novel system that would be easily accessible, informative, protective, and portable.

  13. RTTOV-gb - adapting the fast radiative transfer model RTTOV for the assimilation of ground-based microwave radiometer observations

    NASA Astrophysics Data System (ADS)

    De Angelis, Francesco; Cimini, Domenico; Hocking, James; Martinet, Pauline; Kneifel, Stefan

    2016-08-01

    Ground-based microwave radiometers (MWRs) offer a new capability to provide continuous observations of the atmospheric thermodynamic state in the planetary boundary layer. Thus, they are potential candidates to supplement radiosonde network and satellite data to improve numerical weather prediction (NWP) models through a variational assimilation of their data. However in order to assimilate MWR observations, a fast radiative transfer model is required and such a model is not currently available. This is necessary for going from the model state vector space to the observation space at every observation point. The fast radiative transfer model RTTOV is well accepted in the NWP community, though it was developed to simulate satellite observations only. In this work, the RTTOV code has been modified to allow for simulations of ground-based upward-looking microwave sensors. In addition, the tangent linear, adjoint, and K-modules of RTTOV have been adapted to provide Jacobians (i.e., the sensitivity of observations to the atmospheric thermodynamical state) for ground-based geometry. These modules are necessary for the fast minimization of the cost function in a variational assimilation scheme. The proposed ground-based version of RTTOV, called RTTOV-gb, has been validated against accurate and less time-efficient line-by-line radiative transfer models. In the frequency range commonly used for temperature and humidity profiling (22-60 GHz), root-mean-square brightness temperature differences are smaller than typical MWR uncertainties (˜ 0.5 K) at all channels used in this analysis. Brightness temperatures (TBs) computed with RTTOV-gb from radiosonde profiles have been compared with nearly simultaneous and co-located ground-based MWR observations. Differences between simulated and measured TBs are below 0.5 K for all channels except for the water vapor band, where most of the uncertainty comes from instrumental errors. The Jacobians calculated with the K-module of RTTOV

  14. Grain boundary sliding behaviour of copper and alpha brass at intermediate temperatures

    NASA Technical Reports Server (NTRS)

    Raj, S. V.

    1991-01-01

    The role of grain boundary sliding in copper and Cu-30 pct Zn in the temperature range 0.50-0.72 Tm, where Tm is the absolute melting point of the material, is examined. First, sliding data obtained on these materials are presented. The results indicate that the stress exponent for sliding is similar to that for lattice deformation, while the activation energy for sliding varies between 0.5 and 1.6 of the activation energy for creep. Several models proposed for grain boundary sliding are discussed, and it is shown that they do not account for the observed results on copper and alpha brass. A phenomenological model is proposed, where it is assumed that grain boundary sliding results from the glide of dislocations on secondary slip planes.

  15. Influence of fluid pore pressure on chaotic sliding of tectonic faults

    NASA Astrophysics Data System (ADS)

    Turuntaev, Sergey; Riga, Vasily

    2016-04-01

    The problem of permeable rock pore pressure variation influence on tectonic fault sliding and generation of seismic events was studied in the scope of rate-and-state friction model with two-parametric friction law. The coupled problem of pore-elasticity and fault sliding governed by two-parametric rate-and-state equation was studied numerically. The main modes of the fault sliding were found, and transitions from one mode to another due to the fluid pore pressure change were observed. The conditions for transition from stable to chaotic sliding (considered as an analog of seismic event generations) were found. It was shown, that chaotic sliding has features of Poincare stability and can be characterized by finite values of correlation integral and embedding dimension, which depend on critical shear stresses. Change of the effective critical stresses by the pore pressure variation will result in change of the tectonic fault sliding mode and consequently change of the seismic regime.

  16. Effect of sliding velocity on the tribological behavior of copper and associated nanostructure development

    NASA Astrophysics Data System (ADS)

    Emge, Andrew

    the friction was found to increase with sliding velocity and was strongly influenced by material transfer from the copper to the steel pin. An increase in the coefficient of friction with sliding velocity was observed for the sliding of OFHC copper against Nitronic 40 steel in RBGG tests. The increase in the coefficient of friction was correlated to an increase in subsurface plastic deformation and grain refinement. The growth of the nanocrystalline tribolayer in copper after sliding against 440C stainless steel at varying times was studied at sliding velocities of 0.05 and 1.0 m/s. A sliding velocity of 0.05 m/s produced a consistent nanocrystalline layer in as little as 10 s. The thickness of the nanocrystalline layer grew to an average thickness of 3 microm after 10 ks of sliding, but large variations in thickness were observed. A sliding velocity of 1.0 m/s produced a continuous nanocrystalline layer after 10 s of sliding. Ledges developed on the wear tracks at longer sliding times which greatly influenced the tribolayer thickness making it difficult to quantify. Dynamic recrystallization of the tribolayer also led to difficulties in measuring its thickness.

  17. An LPV Adaptive Observer for Updating a Map Applied to an MAF Sensor in a Diesel Engine.

    PubMed

    Liu, Zhiyuan; Wang, Changhui

    2015-01-01

    In this paper, a new method for mass air flow (MAF) sensor error compensation and an online updating error map (or lookup table) due to installation and aging in a diesel engine is developed. Since the MAF sensor error is dependent on the engine operating point, the error model is represented as a two-dimensional (2D) map with two inputs, fuel mass injection quantity and engine speed. Meanwhile, the 2D map representing the MAF sensor error is described as a piecewise bilinear interpolation model, which can be written as a dot product between the regression vector and parameter vector using a membership function. With the combination of the 2D map regression model and the diesel engine air path system, an LPV adaptive observer with low computational load is designed to estimate states and parameters jointly. The convergence of the proposed algorithm is proven under the conditions of persistent excitation and given inequalities. The observer is validated against the simulation data from engine software enDYNA provided by Tesis. The results demonstrate that the operating point-dependent error of the MAF sensor can be approximated acceptably by the 2D map from the proposed method. PMID:26512675

  18. An LPV Adaptive Observer for Updating a Map Applied to an MAF Sensor in a Diesel Engine.

    PubMed

    Liu, Zhiyuan; Wang, Changhui

    2015-10-23

    In this paper, a new method for mass air flow (MAF) sensor error compensation and an online updating error map (or lookup table) due to installation and aging in a diesel engine is developed. Since the MAF sensor error is dependent on the engine operating point, the error model is represented as a two-dimensional (2D) map with two inputs, fuel mass injection quantity and engine speed. Meanwhile, the 2D map representing the MAF sensor error is described as a piecewise bilinear interpolation model, which can be written as a dot product between the regression vector and parameter vector using a membership function. With the combination of the 2D map regression model and the diesel engine air path system, an LPV adaptive observer with low computational load is designed to estimate states and parameters jointly. The convergence of the proposed algorithm is proven under the conditions of persistent excitation and given inequalities. The observer is validated against the simulation data from engine software enDYNA provided by Tesis. The results demonstrate that the operating point-dependent error of the MAF sensor can be approximated acceptably by the 2D map from the proposed method.

  19. An LPV Adaptive Observer for Updating a Map Applied to an MAF Sensor in a Diesel Engine

    PubMed Central

    Liu, Zhiyuan; Wang, Changhui

    2015-01-01

    In this paper, a new method for mass air flow (MAF) sensor error compensation and an online updating error map (or lookup table) due to installation and aging in a diesel engine is developed. Since the MAF sensor error is dependent on the engine operating point, the error model is represented as a two-dimensional (2D) map with two inputs, fuel mass injection quantity and engine speed. Meanwhile, the 2D map representing the MAF sensor error is described as a piecewise bilinear interpolation model, which can be written as a dot product between the regression vector and parameter vector using a membership function. With the combination of the 2D map regression model and the diesel engine air path system, an LPV adaptive observer with low computational load is designed to estimate states and parameters jointly. The convergence of the proposed algorithm is proven under the conditions of persistent excitation and given inequalities. The observer is validated against the simulation data from engine software enDYNA provided by Tesis. The results demonstrate that the operating point-dependent error of the MAF sensor can be approximated acceptably by the 2D map from the proposed method. PMID:26512675

  20. Herbaceous Ornamental Plants. Slide Script.

    ERIC Educational Resources Information Center

    Still, Steven

    This document, which is one in a series of curriculum materials that has been developed for use in Ohio agricultural education programs, contains 338 black-and-white photographs of a set of color slides and an accompanying script that, together, are intended as an aid in the study and identification of 150 different commercially important…

  1. Automatic 35 mm slide duplicator

    NASA Technical Reports Server (NTRS)

    Seidel, H. F.; Texler, R. E.

    1980-01-01

    Automatic duplicator is readily assembled from conventional, inexpensive equipment and parts. Series of slides can be exposed without operator attention, eliminating considerable manual handling and processing ordinarily required. At end of programmed exposure sequence, unit shuts off and audible alarm signals completion of process.

  2. Resultant knee joint moments for lateral movement tasks on sliding and non-sliding sport surfaces.

    PubMed

    Nigg, Benno M; Stefanyshyn, Darren J; Rozitis, Antra I; Mundermann, Annegret

    2009-03-01

    The aim of this study was to compare ankle and knee joint moments observed when playing on sport surfaces that slide slightly relative to the ground with the moments observed when playing on conventional sport surfaces. Three-dimensional resultant internal joint moments and kinematic characteristics of the lower extremity were quantified for 21 university basketball players when performing v-cut and side-shuffle tasks on three types of sliding surface (interlocking tiles) and on two types of conventional surface (maple wood and rolled vinyl). Translational and rotational friction between the five test surfaces and a test shoe were also quantified. The five sport surfaces moved horizontally between 0.2 and 1.6 mm during the landing phase of the two tasks. The medio-lateral ground reaction forces were lowest for the surfaces with the highest horizontal movement. Resultant ankle joint moments were lower and resultant knee moments were higher on the sliding surfaces than the conventional surfaces. Sport surfaces that allow a few millimetres of horizontal movement during ground contact may reduce joint loading at the ankle joint, but increase joint loading at the knee joint, when compared with conventional sport surfaces, and thus may influence the prevalence of knee injuries.

  3. Sliding Mode Control (SMC) of Robot Manipulator via Intelligent Controllers

    NASA Astrophysics Data System (ADS)

    Kapoor, Neha; Ohri, Jyoti

    2016-06-01

    Inspite of so much research, key technical problem, naming chattering of conventional, simple and robust SMC is still a challenge to the researchers and hence limits its practical application. However, newly developed soft computing based techniques can provide solution. In order to have advantages of conventional and heuristic soft computing based control techniques, in this paper various commonly used intelligent techniques, neural network, fuzzy logic and adaptive neuro fuzzy inference system (ANFIS) have been combined with sliding mode controller (SMC). For validation, proposed hybrid control schemes have been implemented for tracking a predefined trajectory by robotic manipulator, incorporating structured and unstructured uncertainties in the system. After reviewing numerous papers, all the commonly occurring uncertainties like continuous disturbance, uniform random white noise, static friction like coulomb friction and viscous friction, dynamic friction like Dhal friction and LuGre friction have been inserted in the system. Various performance indices like norm of tracking error, chattering in control input, norm of input torque, disturbance rejection, chattering rejection have been used. Comparative results show that with almost eliminated chattering the intelligent SMC controllers are found to be more efficient over simple SMC. It has also been observed from results that ANFIS based controller has the best tracking performance with the reduced burden on the system. No paper in the literature has found to have all these structured and unstructured uncertainties together for motion control of robotic manipulator.

  4. Surface layer structure of AISI 1020 steel at different stages of dry sliding under electric current of high density

    NASA Astrophysics Data System (ADS)

    Aleutdinov, K. A.; Rubtsov, V. Ye; Fadin, V. V.; Aleutdinova, M. I.

    2016-02-01

    Wear intensity of the sliding electric contact steel 1020/steel 1045 depending on sliding time is presented at the contact current density higher than 100 A/cm2 without lubricant. It is shown that wear intensity of 1020 steel decreases at increasing of sliding time. Wear intensity is stabilized after some sliding time. This time (burn-in time) decreases at reduction of current density. Structural changes are realized in surface layer. Signs of liquid phase are observed on sliding surface. This liquid isn't a result of melting. It is established using Auger spectrometry that the contact layer contains up to 50 at.% of oxygen.

  5. Diseases of Landscape Ornamentals. Slide Script.

    ERIC Educational Resources Information Center

    Powell, Charles C.; Sydnor, T. Davis

    This slide script, part of a series of slide scripts designed for use in vocational agriculture classes, deals with recognizing and controlling diseases found on ornamental landscape plants. Included in the script are narrations for use with a total of 80 slides illustrating various foliar diseases (anthracnose, black spot, hawthorn leaf blight,…

  6. Linear Classification of Dairy Cattle. Slide Script.

    ERIC Educational Resources Information Center

    Sipiorski, James; Spike, Peter

    This slide script, part of a series of slide scripts designed for use in vocational agriculture classes, deals with principles of the linear classification of dairy cattle. Included in the guide are narrations for use with 63 slides, which illustrate the following areas that are considered in the linear classification system: stature, strength,…

  7. Approved Practices in Dairy Reproduction. Slide Script.

    ERIC Educational Resources Information Center

    Roediger, Roger D.; Barr, Harry L.

    This slide script, part of a series of slide scripts designed for use in vocational agriculture classes, deals with approved practices in dairy reproduction. Included in the guide are narrations for use with 200 slides dealing with the following topics: the importance of good reproduction, the male and female roles in reproduction, selection of…

  8. Slide crown lengthening procedure using wide surface incisions and cyanoacrylate.

    PubMed

    Szymaitis, Dennis W

    2011-01-01

    This article introduces the slide crown lengthening procedure (SCLP), which incorporates surgical design features to overcome present crown lengthening procedure (CLP) shortcomings. The result is a 75% decrease in required surgery on adjacent teeth and a corresponding 75% reduction in surgical time. Other advantages include a reduction in surgical morbidity, improvement in terminal esthetics, and fewer teeth subject to papillae removal and apically repositioned gingiva. The 20 to 30 degree incision forming the slide is the pivotal feature; it allows effortless flap positioning. This incision angle enables wide surface incisions to adhere flaps together by producing stronger fibrin clots, decreasing tissue retraction angles, and reforming disrupted fibrin clots as incision sides slide while maintaining contact. This enhanced fibrin clot eliminates the need for sutures. The slide produced by the 20 to 30 degree incision functions for crown lengthening on all sites (facial, lingual, or palatal). This versatile surgical design introduces a new healing dimension that adapts to and provides benefits for other dental surgeries, such as gingival grafts, endodontic surgery, implants, and extractions.

  9. Pressure vessel sliding support unit and system using the sliding support unit

    DOEpatents

    Breach, Michael R.; Keck, David J.; Deaver, Gerald A.

    2013-01-15

    Provided is a sliding support and a system using the sliding support unit. The sliding support unit may include a fulcrum capture configured to attach to a support flange, a fulcrum support configured to attach to the fulcrum capture, and a baseplate block configured to support the fulcrum support. The system using the sliding support unit may include a pressure vessel, a pedestal bracket, and a plurality of sliding support units.

  10. Adaptive Square-Root Cubature-Quadrature Kalman Particle Filter for satellite attitude determination using vector observations

    NASA Astrophysics Data System (ADS)

    Kiani, Maryam; Pourtakdoust, Seid H.

    2014-12-01

    A novel algorithm is presented in this study for estimation of spacecraft's attitudes and angular rates from vector observations. In this regard, a new cubature-quadrature particle filter (CQPF) is initially developed that uses the Square-Root Cubature-Quadrature Kalman Filter (SR-CQKF) to generate the importance proposal distribution. The developed CQPF scheme avoids the basic limitation of particle filter (PF) with regards to counting the new measurements. Subsequently, CQPF is enhanced to adjust the sample size at every time step utilizing the idea of confidence intervals, thus improving the efficiency and accuracy of the newly proposed adaptive CQPF (ACQPF). In addition, application of the q-method for filter initialization has intensified the computation burden as well. The current study also applies ACQPF to the problem of attitude estimation of a low Earth orbit (LEO) satellite. For this purpose, the undertaken satellite is equipped with a three-axis magnetometer (TAM) as well as a sun sensor pack that provide noisy geomagnetic field data and Sun direction measurements, respectively. The results and performance of the proposed filter are investigated and compared with those of the extended Kalman filter (EKF) and the standard particle filter (PF) utilizing a Monte Carlo simulation. The comparison demonstrates the viability and the accuracy of the proposed nonlinear estimator.

  11. Automated single-slide staining device

    NASA Technical Reports Server (NTRS)

    Wilkins, J. R.; Mills, S. M. (Inventor)

    1977-01-01

    A simple apparatus and method is disclosed for making individual single Gram stains on bacteria inoculated slides to assist in classifying bacteria in the laboratory as Gram-positive or Gram-negative. The apparatus involves positioning a single inoculated slide in a stationary position and thereafter automatically and sequentially flooding the slide with increments of a primary stain, a mordant, a decolorizer, a counterstain and a wash solution in a sequential manner without the individual lab technician touching the slide and with minimum danger of contamination thereof from other slides.

  12. Near-infrared polarimetric adaptive optics observations of NGC 1068: a torus created by a hydromagnetic outflow wind

    NASA Astrophysics Data System (ADS)

    Lopez-Rodriguez, E.; Packham, C.; Jones, T. J.; Nikutta, R.; McMaster, L.; Mason, R. E.; Elvis, M.; Shenoy, D.; Alonso-Herrero, A.; Ramírez, E.; González Martín, O.; Hönig, S. F.; Levenson, N. A.; Ramos Almeida, C.; Perlman, E.

    2015-09-01

    We present J' and K' imaging linear polarimetric adaptive optics observations of NGC 1068 using MMT-Pol on the 6.5-m MMT. These observations allow us to study the torus from a magnetohydrodynamical (MHD) framework. In a 0.5 arcsec (30 pc) aperture at K', we find that polarization arising from the passage of radiation from the inner edge of the torus through magnetically aligned dust grains in the clumps is the dominant polarization mechanism, with an intrinsic polarization of 7.0 ± 2.2 per cent. This result yields a torus magnetic field strength in the range of 4-82 mG through paramagnetic alignment, and 139^{+11}_{-20} mG through the Chandrasekhar-Fermi method. The measured position angle (P.A.) of polarization at K' is found to be similar to the P.A. of the obscuring dusty component at few parsec scales using infrared interferometric techniques. We show that the constant component of the magnetic field is responsible for the alignment of the dust grains, and aligned with the torus axis on to the plane of the sky. Adopting this magnetic field configuration and the physical conditions of the clumps in the MHD outflow wind model, we estimate a mass outflow rate ≤0.17 M⊙ yr-1 at 0.4 pc from the central engine for those clumps showing near-infrared dichroism. The models used were able to create the torus in a time-scale of ≥105 yr with a rotational velocity of ≤1228 km s-1 at 0.4 pc. We conclude that the evolution, morphology and kinematics of the torus in NGC 1068 can be explained within a MHD framework.

  13. Time variability of Io's volcanic activity from near-IR adaptive optics observations on 100 nights in 2013-2015

    NASA Astrophysics Data System (ADS)

    de Kleer, Katherine; de Pater, Imke

    2016-12-01

    Jupiter's moon Io is a dynamic target, exhibiting extreme and time-variable volcanic activity powered by tidal forcing from Jupiter. We have conducted a campaign of high-cadence observations of Io with the goal of characterizing its volcanic activity. Between Aug 2013 and the end of 2015, we imaged Io on 100 nights in the near-infrared with adaptive optics on the Keck and Gemini N telescopes, which resolve emission from individual volcanic hot spots. During our program, we made over 400 detections of 48 distinct hot spots, some of which were detected 30+ times. We use these observations to derive a timeline of global volcanic activity on Io, which exhibits wide variability from month to month. The timelines of thermal activity at individual volcanic centers have geophysical implications, and will permit future characterization by others. We evaluate hot spot detection limits and give a simple parameterization of the minimum detectable intensity as a function of emission angle, which can be applied to other analyses. We detected three outburst eruptions in August 2013, but no other outburst-scale events were observed in the subsequent ∼90 observations. Either the cluster of events in August 2013 was a rare occurrence, or there is a mechanism causing large events to occur closely-spaced in time. We also detected large eruptions (though not of outburst scale) within days of one another at Kurdalagon Patera and Sethlaus/Gabija Paterae in 2015. As was also seen in the Galileo dataset, the hot spots we detected can be separated into two categories based on their thermal emission: those that are persistently active for 1 year or more at moderate intensity, and those that are only briefly active, are time-variable, and often reach large intensities. A small number of hot spots in the latter category appear and subside in a matter of days, reaching particularly high intensities; although these are not bright enough to qualify as outbursts, their thermal signatures follow

  14. Atomic-Scale Sliding Friction on Graphene in Water.

    PubMed

    Vilhena, J G; Pimentel, Carlos; Pedraz, Patricia; Luo, Feng; Serena, Pedro A; Pina, Carlos M; Gnecco, Enrico; Pérez, Rubén

    2016-04-26

    The sliding of a sharp nanotip on graphene completely immersed in water is investigated by molecular dynamics (MD) and atomic force microscopy. MD simulations predict that the atomic-scale stick-slip is almost identical to that found in ultrahigh vacuum. Furthermore, they show that water plays a purely stochastic role in sliding (solid-to-solid) friction. These observations are substantiated by friction measurements on graphene grown on Cu and Ni, where, oppositely of the operation in air, lattice resolution is readily achieved. Our results promote friction force microscopy in water as a robust alternative to ultra-high-vacuum measurements. PMID:26982997

  15. Atomic-Scale Sliding Friction on Graphene in Water.

    PubMed

    Vilhena, J G; Pimentel, Carlos; Pedraz, Patricia; Luo, Feng; Serena, Pedro A; Pina, Carlos M; Gnecco, Enrico; Pérez, Rubén

    2016-04-26

    The sliding of a sharp nanotip on graphene completely immersed in water is investigated by molecular dynamics (MD) and atomic force microscopy. MD simulations predict that the atomic-scale stick-slip is almost identical to that found in ultrahigh vacuum. Furthermore, they show that water plays a purely stochastic role in sliding (solid-to-solid) friction. These observations are substantiated by friction measurements on graphene grown on Cu and Ni, where, oppositely of the operation in air, lattice resolution is readily achieved. Our results promote friction force microscopy in water as a robust alternative to ultra-high-vacuum measurements.

  16. Tribological Behaviour of PTFE Under Variable Loading Dry Sliding Condition

    NASA Astrophysics Data System (ADS)

    Patil, S. M.; Ahuja, B. B.

    2014-04-01

    To study the tribological behaviour of materials subjected to variable and constant loading the pin-on-disk tribometer has been modified. This paper discusses the wear and friction behaviour of Poly Tetra Fluoro Ethylene (PTFE) operating under variable loading dry unidirectional sliding condition using the modified tribometer. The results under variable loading are compared with corresponding maximum, minimum and mean constant load situations. Wear and specific wear rate of PTFE subjected to variable loading under dry unidirectional sliding condition lies above those of corresponding mean constant load but no such comparative behaviour was observed for coefficient of friction.

  17. Occurrence of spherical ceramic debris in indentation and sliding contact

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1982-01-01

    Indenting experiments were conducted with the silicon carbide (0001) surface in contact with a spherical diamond indenter in air. Sliding friction experiments were also conducted with silicon carbide in contact with iron and iron-based binary alloys at room temperature and 800 C. Fracture pits with a spherical particle and spherical wear debris were observed as a result of indenting and sliding. Spherical debris may be produced by a mechanism that involves a spherical-shaped fracture along the circular or spherical stress trajectories under the inelastic deformation zone.

  18. Tribological study of selected ceramics versus metal sliding couples

    SciTech Connect

    Matsuhiro, K.; Sakai, H.; Soma, T.; Oda, I.

    1987-01-01

    A tribological study has been done with dry and lubricated conditions on the several selected sliding couples of ceramics vs. ceramics, ceramics vs. metal and ceramics vs. plasma sprayed metal. Sliding velocity was 2.6m/s (8.5ft/s), load was 22N and temperature was room temperature to 540/sup 0/C (1000/sup 0/F). No significant wear was observed on any sliding couples when they were lubricated. A considerably better tribological character was found in the ceramics vs. metal couple with dry condition. Especially sintered silicon nitride (SSN) vs. LiF+Cu plasma sprayed M2 steel at room temperature to 540/sup 0/C and SSN vs. M2 steel couple at 540/sup 0/C were remarkable. It is considered that the tribological character between ceramics and metal contact may be controlled by adhesion of metal to ceramics.

  19. An Evaluation of a Biological Slide-Tutorial Program.

    ERIC Educational Resources Information Center

    Chan, Gordon L.

    Described is an auto-tutorial slide program for zoology students. A self-paced system was devised for observing the subject matter covered in the twelve study units of a zoology course. The post-testing evaluation revealed that students with lower grade point averages achieved scores comparable with students of higher grade point averages.…

  20. Understanding Learning Style by Eye Tracking in Slide Video Learning

    ERIC Educational Resources Information Center

    Cao, Jianxia; Nishihara, Akinori

    2012-01-01

    More and more videos are now being used in e-learning context. For improving learning effect, to understand how students view the online video is important. In this research, we investigate how students deploy their attention when they learn through interactive slide video in the aim of better understanding observers' learning style. Felder and…

  1. Prediction of a landslide and analysis of slide motion with reference to the 2004 Ohto slide in Nara, Japan

    NASA Astrophysics Data System (ADS)

    Suwa, Hiroshi; Mizuno, Takashi; Ishii, Takayuki

    2010-12-01

    A slope 120 m wide and 100 m high collapsed including the roadbed of a national highway of Route 168 at Ohto, Nara, Japan on August 10, 2004. The precursory phenomena of abnormal features were found as cracks growing on the road-side slope 7 months before the catastrophe. The movements of the slope were monitored by extensometers. The data of the extensometers showed that creep mode turned from the secondary into the tertiary due to the heavy rainstorm of Typhoon Namtheun. The slide claimed no victims because the highway was closed 43 h before the catastrophe, anticipating a possible hazard when the creep velocity reached 4 mm/2 h. Comparison of rupture time predictions suggested that precision of the prediction using the reciprocal of creep velocity is higher than that by tertiary creep analysis, although leaving a problem that the prediction of the time zone of failure erred on the dangerous side. The slide generated ground vibration which was observed by seismometers deployed around the slide. Duration of the seismic signals corresponded well with the slide motion deciphered from video records. We found the fact that the seismic energy radiation from a landslide consisted of four stages. This had not been reported in any previous study, and may be important in understanding the dynamics of a rock-slide avalanche.

  2. Improving the Forecast Accuracy of an Ocean Observation and Prediction System by Adaptive Control of the Sensor Network

    NASA Astrophysics Data System (ADS)

    Talukder, A.; Panangadan, A. V.; Blumberg, A. F.; Herrington, T.; Georgas, N.

    2008-12-01

    The New York Harbor Observation and Prediction System (NYHOPS) is a real-time, estuarine and coastal ocean observing and modeling system for the New York Harbor and surrounding waters. Real-time measurements from in-situ mobile and stationary sensors in the NYHOPS networks are assimilated into marine forecasts in order to reduce the discrepancy with ground truth. The forecasts are obtained from the ECOMSED hydrodynamic model, a shallow water derivative of the Princeton Ocean Model. Currently, all sensors in the NYHOPS system are operated in a fixed mode with uniform sampling rates. This technology infusion effort demonstrates the use of Model Predictive Control (MPC) to autonomously adapt the operation of both mobile and stationary sensors in response to changing events that are -automatically detected from the ECOMSED forecasts. The controller focuses sensing resources on those regions that are expected to be impacted by the detected events. The MPC approach involves formulating the problem of calculating the optimal sensor parameters as a constrained multi-objective optimization problem. We have developed an objective function that takes into account the spatiotemporal relationship of the in-situ sensor locations and the locations of events detected by the model. Experiments in simulation were carried out using data collected during a freshwater flooding event. The location of the resulting freshwater plume was calculated from the corresponding model forecasts and was used by the MPC controller to derive control parameters for the sensing assets. The operational parameters that are controlled include the sampling rates of stationary sensors, paths of unmanned underwater vehicles (UUVs), and data transfer routes between sensors and the central modeling computer. The simulation experiments show that MPC-based sensor control reduces the RMS error in the forecast by a factor of 380% as compared to uniform sampling. The paths of multiple UUVs were simultaneously

  3. Sliding viscoelastic drops on slippery surfaces

    NASA Astrophysics Data System (ADS)

    Xu, H.; Clarke, A.; Rothstein, J. P.; Poole, R. J.

    2016-06-01

    We study the sliding of drops of constant-viscosity dilute elastic liquids (Boger fluids) on various surfaces caused by sudden surface inclination. For smooth or roughened hydrophilic surfaces, such as glass or acrylic, there is essentially no difference between these elastic liquids and a Newtonian comparator fluid (with identical shear viscosity, surface tension, and static contact angle). In contrast for embossed polytetrafluoroethylene superhydrophobic surfaces, profound differences are observed: the elastic drops slide at a significantly reduced rate and complex branch-like patterns are left on the surface by the drop's wake including, on various scales, beads-on-a-string like phenomena. Microscopy images indicate that the strong viscoelastic effect is caused by stretching filaments of fluid from isolated islands, residing at pinning sites on the surface pillars, of the order ˜30 μm in size. On this scale, the local strain rates are sufficient to extend the polymer chains, locally increasing the extensional viscosity of the solution, retarding the drop and leaving behind striking branch-like structures on much larger scales.

  4. Physiological Observations and Omics to Develop Personalized Sensormotor Adaptability Countermeasures Using Bed Rest and Space Flight Data

    NASA Technical Reports Server (NTRS)

    Mulavara, A. P.; Seidler, R. D.; Feiveson, A.; Oddsson, L.; Zanello, S.; Oman, C. M.; Ploutz-Snyder, L.; Peters, B.; Cohen, H. S.; Reschke, M.; Wood, S.; Bloomberg, J. J.

    2014-01-01

    Astronauts experience sensorimotor disturbances during the initial exposure to microgravity and during the re-adapation phase following a return to an earth-gravitational environment. These alterations may disrupt the ability to perform mission critical functional tasks requiring ambulation, manual control and gaze stability. Interestingly, astronauts who return from space flight show substantial differences in their abilities to readapt to a gravitational environment. The ability to predict the manner and degree to which individual astronauts would be affected would improve the effectiveness of countermeasure training programs designed to enhance sensorimotor adaptability. For such an approach to succeed, we must develop predictive measures of sensorimotor adaptability that will allow us to foresee, before actual space flight, which crewmembers are likely to experience the greatest challenges to their adaptive capacities. The goals of this project are to identify and characterize this set of predictive measures that include: 1) behavioral tests to assess sensory bias and adaptability quantified using both strategic and plastic-adaptive responses; 2) imaging to determine individual brain morphological and functional features using structural magnetic resonance imaging (MRI), diffusion tensor imaging, resting state functional connectivity MRI, and sensorimotor adaptation task-related functional brain activation; 3) genotype markers for genetic polymorphisms in Catechol-O-Methyl Transferase, Dopamine Receptor D2, Brain-derived neurotrophic factor and genetic polymorphism of alpha2-adrenergic receptor that play a role in the neural pathways underlying sensorimotor adaptation. We anticipate these predictive measures will be significantly correlated with individual differences in sensorimotor adaptability after long-duration space flight and an analog bed rest environment. We will be conducting a retrospective study leveraging data already collected from relevant

  5. 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

  6. Earth Observation in Support of the Development of the Adaptation Plans for Climate Change in Cities: An Application for the Thermal Environment in Athens, Greece

    NASA Astrophysics Data System (ADS)

    Cartalis, C.; Polydoros, A.; Mavrakou, Th.; Asimakopoulos, D. N.

    2014-11-01

    The development of adaptation plans for climate change in cities need to reflect how urban mechanisms are influenced by the transfer of heat and the reflection/emission of electromagnetic radiation. For doing so, a thorough knowledge of a number of urban parameters is needed, namely of the land surface albedo, the land surface emissivity and the land surface temperature. Furthermore, information on land use and land cover as well as a Digital Elevation Model of the area concerned are needed. In this paper, the potential of Earth Observation to support the extraction and spatial/temporal representation of the above parameters, in support of adaptation plans for climate change is examined.

  7. Self-Sustained Oscillatory Sliding Movement of Doublet Microtubules and Flagellar Bend Formation.

    PubMed

    Ishijima, Sumio

    2016-01-01

    It is well established that the basis for flagellar and ciliary movements is ATP-dependent sliding between adjacent doublet microtubules. However, the mechanism for converting microtubule sliding into flagellar and ciliary movements has long remained unresolved. The author has developed new sperm models that use bull spermatozoa divested of their plasma membrane and midpiece mitochondrial sheath by Triton X-100 and dithiothreitol. These models enable the observation of both the oscillatory sliding movement of activated doublet microtubules and flagellar bend formation in the presence of ATP. A long fiber of doublet microtubules extruded by synchronous sliding of the sperm flagella and a short fiber of doublet microtubules extruded by metachronal sliding exhibited spontaneous oscillatory movements and constructed a one beat cycle of flagellar bending by alternately actuating. The small sliding displacement generated by metachronal sliding formed helical bends, whereas the large displacement by synchronous sliding formed planar bends. Therefore, the resultant waveform is a half-funnel shape, which is similar to ciliary movements. PMID:26863204

  8. A mechanism of stick-slip fault sliding without friction rate dependence and supersonic wave propagation

    NASA Astrophysics Data System (ADS)

    Karachevtseva, Iuliia; Dyskin, Arcady; Pasternak, Elena

    2015-04-01

    Stick-slip sliding is often observed at various scales and in particular in fault sliding and the accompanied seismic events. Stick-slip is conventionally associated with rate-dependent friction, in particular the intermittent change between static and kinetic friction. However the accumulation of elastic energy in the sliding plates on both sides of the fault can produce oscillations in the velocity of sliding even if the friction coefficient is constant. This manifests itself in terms of oscillations in the sliding velocity somewhat resembling the stick-slip movement. Furthermore, over long faults the sliding exhibits wave-like propagation. We present a model that shows that the zones of non-zero sliding velocities propagate along the fault with the velocity of p-wave. The mechanism of such fast wave propagation is the normal (tensile/compressive) stresses in the neighbouring elements (normal stresses on the planes normal to the fault surface). The strains associated with these stresses are controlled by the Young's modulus rather than shear modulus resulting in the p-wave velocity of propagation of the sliding zone. This manifests itself as a supersonic (with respect to the s-waves) propagation of an apparent shear rupture.

  9. Self-Sustained Oscillatory Sliding Movement of Doublet Microtubules and Flagellar Bend Formation

    PubMed Central

    Ishijima, Sumio

    2016-01-01

    It is well established that the basis for flagellar and ciliary movements is ATP-dependent sliding between adjacent doublet microtubules. However, the mechanism for converting microtubule sliding into flagellar and ciliary movements has long remained unresolved. The author has developed new sperm models that use bull spermatozoa divested of their plasma membrane and midpiece mitochondrial sheath by Triton X-100 and dithiothreitol. These models enable the observation of both the oscillatory sliding movement of activated doublet microtubules and flagellar bend formation in the presence of ATP. A long fiber of doublet microtubules extruded by synchronous sliding of the sperm flagella and a short fiber of doublet microtubules extruded by metachronal sliding exhibited spontaneous oscillatory movements and constructed a one beat cycle of flagellar bending by alternately actuating. The small sliding displacement generated by metachronal sliding formed helical bends, whereas the large displacement by synchronous sliding formed planar bends. Therefore, the resultant waveform is a half-funnel shape, which is similar to ciliary movements. PMID:26863204

  10. Dynamical chiral symmetry breaking in sliding nanotubes.

    PubMed

    Zhang, X H; Santoro, G E; Tartaglino, U; Tosatti, E

    2009-03-27

    We discover in simulations of sliding coaxial nanotubes an unanticipated example of dynamical symmetry breaking taking place at the nanoscale. While both nanotubes are perfectly left-right symmetric and nonchiral, a nonzero angular momentum of phonon origin appears spontaneously at a series of critical sliding velocities, in correspondence with large peaks of the sliding friction. The nonlinear equations governing this phenomenon resemble the rotational instability of a forced string. However, several new elements, exquisitely "nano" appear here, with the crucial involvement of umklapp and of sliding nanofriction.

  11. Tape-recorded Lectures With Slide Synchronization

    ERIC Educational Resources Information Center

    Goodhue, D.

    1969-01-01

    Describes "Taped Explanation Slide Synchronization" programs used for individual study or group showing in college zoology. Discusses preparation of programs, class organization, equipment, and costs. (EB)

  12. Instant slides of radiographs for lectures.

    PubMed

    Rothstein, S G; Stewart, P L

    1989-10-01

    High quality slides of radiographs may be made with a simple, fast, and inexpensive technique using Kodak Rapid Process Copy film. Lecture presentations may include a slide of a pertinent plain radiograph, computed tomography (CT) scan, or magnetic resonance imaging (MRI). Although these slides may be made with a 35 mm SLR camera and flash or with a 35 mm SLR camera and a lighted viewbox, an alternative method is available that is easy to perform, inexpensive, and can produce quality slides in as little as 30 minutes. PMID:2477785

  13. "Slide less pathology": Fairy tale or reality?

    PubMed

    Indu, M; Rathy, R; Binu, M P

    2016-01-01

    Pathology practice is significantly advanced in various frontiers. Therefore, "slide less digital" pathology will not be a mere imagination in near future. Digitalization of histopathological slides (whole slide imaging [WSI]) is possible with the help of whole slide scanner. The WSI has a positive impact not only in routine practice but also in research field, medical education and bioindustry. Even if digital pathology has definitive advantages, its widespread use is not yet possible. As it is an upcoming technology in our field, this article is aimed to discussessential aspects of WSI. PMID:27601824

  14. Depth Estimation Using a Sliding Camera.

    PubMed

    Ge, Kailin; Hu, Han; Feng, Jianjiang; Zhou, Jie

    2016-02-01

    Image-based 3D reconstruction technology is widely used in different fields. The conventional algorithms are mainly based on stereo matching between two or more fixed cameras, and high accuracy can only be achieved using a large camera array, which is very expensive and inconvenient in many applications. Another popular choice is utilizing structure-from-motion methods for arbitrarily placed camera(s). However, due to too many degrees of freedom, its computational cost is heavy and its accuracy is rather limited. In this paper, we propose a novel depth estimation algorithm using a sliding camera system. By analyzing the geometric properties of the camera system, we design a camera pose initialization algorithm that can work satisfyingly with only a small number of feature points and is robust to noise. For pixels corresponding to different depths, an adaptive iterative algorithm is proposed to choose optimal frames for stereo matching, which can take advantage of continuously pose-changing imaging and save the time consumption amazingly too. The proposed algorithm can also be easily extended to handle less constrained situations (such as using a camera mounted on a moving robot or vehicle). Experimental results on both synthetic and real-world data have illustrated the effectiveness of the proposed algorithm. PMID:26685238

  15. Depth Estimation Using a Sliding Camera.

    PubMed

    Ge, Kailin; Hu, Han; Feng, Jianjiang; Zhou, Jie

    2016-02-01

    Image-based 3D reconstruction technology is widely used in different fields. The conventional algorithms are mainly based on stereo matching between two or more fixed cameras, and high accuracy can only be achieved using a large camera array, which is very expensive and inconvenient in many applications. Another popular choice is utilizing structure-from-motion methods for arbitrarily placed camera(s). However, due to too many degrees of freedom, its computational cost is heavy and its accuracy is rather limited. In this paper, we propose a novel depth estimation algorithm using a sliding camera system. By analyzing the geometric properties of the camera system, we design a camera pose initialization algorithm that can work satisfyingly with only a small number of feature points and is robust to noise. For pixels corresponding to different depths, an adaptive iterative algorithm is proposed to choose optimal frames for stereo matching, which can take advantage of continuously pose-changing imaging and save the time consumption amazingly too. The proposed algorithm can also be easily extended to handle less constrained situations (such as using a camera mounted on a moving robot or vehicle). Experimental results on both synthetic and real-world data have illustrated the effectiveness of the proposed algorithm.

  16. Slide Tape. A Guide to the Production of Slide-Tape Programmes.

    ERIC Educational Resources Information Center

    Rowatt, Robert W.

    Step by step instructions are provided for planning and executing a slide tape program, as well as diagrams of equipment for presenting such programs. Guidelines are given for ways to: (1) define a program's purpose and objectives, (2) complete a storyboard, (3) produce slides from transparencies and photographed artwork, (4) write on slides, (5)…

  17. Rate-weakening friction characterizes both slow sliding and catastrophic failure of landslides

    NASA Astrophysics Data System (ADS)

    Handwerger, Alexander L.; Rempel, Alan W.; Skarbek, Rob M.; Roering, Joshua J.; Hilley, George E.

    2016-09-01

    Catastrophic landslides cause billions of dollars in damages and claim thousands of lives annually, whereas slow-moving landslides with negligible inertia dominate sediment transport on many weathered hillslopes. Surprisingly, both failure modes are displayed by nearby landslides (and individual landslides in different years) subjected to almost identical environmental conditions. Such observations have motivated the search for mechanisms that can cause slow-moving landslides to transition via runaway acceleration to catastrophic failure. A similarly diverse range of sliding behavior, including earthquakes and slow-slip events, occurs along tectonic faults. Our understanding of these phenomena has benefitted from mechanical treatments that rely upon key ingredients that are notably absent from previous landslide descriptions. Here, we describe landslide motion using a rate- and state-dependent frictional model that incorporates a nonlocal stress balance to account for the elastic response to gradients in slip. Our idealized, one-dimensional model reproduces both the displacement patterns observed in slow-moving landslides and the acceleration toward failure exhibited by catastrophic events. Catastrophic failure occurs only when the slip surface is characterized by rate-weakening friction and its lateral dimensions exceed a critical nucleation length h*h* that is shorter for higher effective stresses. However, landslides that are extensive enough to fall within this regime can nevertheless slide slowly for months or years before catastrophic failure. Our results suggest that the diversity of slip behavior observed during landslides can be described with a single model adapted from standard fault mechanics treatments.

  18. [Heritage Education Lesson Plans and Slide Presentations].

    ERIC Educational Resources Information Center

    Van Buren, Maurie

    Field tested in 27 schools and in grades four through twelve, this teaching unit stresses heritage education through the study of southern U.S. architectural styles for homes from the pioneer log structures to the 1950s ranch home. Each of the four lessons in this unit focuses around a slide presentation of 20 slides designed to fit into one…

  19. Getting Clever with the Sliding Ladder

    ERIC Educational Resources Information Center

    De, Subhranil

    2014-01-01

    The familiar system involving a uniform ladder sliding against a vertical wall and a horizontal floor is considered again. The floor is taken to be smooth and the wall to be possibly rough--a situation where no matter how large the static friction coefficient between the ladder and the wall, the ladder cannot lean at rest and must slide down.…

  20. The Cancer Digital Slide Archive - TCGA

    Cancer.gov

    Dr. David Gutman and Dr. Lee Cooper developed The Cancer Digital Slide Archive (CDSA), a web platform for accessing pathology slide images of TCGA samples. Find out how they did it and how to use the CDSA website in this Case Study.

  1. Thermal and thermomechanical effects in dry sliding

    NASA Technical Reports Server (NTRS)

    Kennedy, F. E., Jr.

    1984-01-01

    Developments in the study of interrelated thermal and mechanical phenomena in sliding systems are reviewed. The topics reviewed include mechanisms of frictional heating and the distribution of heat during sliding friction, the experimental measurement and analysis of surface and near-surface temperatures resulting from frictional heating, thermal deformation around sliding contacts and the changes in contact geometry caused by thermal deformation and thermoelastic instability, and the thermomechanical stress distribution around the frictionally heated and thermally deformed contact spots. The influence of the thermal and thermomechanical contact phenomena on friction and wear, surface melting, softening, chemical deterioration, and thermocracking are discussed. The phenomena have important implications in the design and application of sliding or sliding-rolling mechanical components such as dynamic seals, brakes, clutches, plastic bearings, solid or boundary-lubricated bearings, and gears.

  2. A Sliding Mode Control with Optimized Sliding Surface for Aircraft Pitch Axis Control System

    NASA Astrophysics Data System (ADS)

    Lee, Sangchul; Kim, Kwangjin; Kim, Youdan

    A sliding mode controller with an optimized sliding surface is proposed for an aircraft control system. The quadratic type of performance index for minimizing the angle of attack and the angular rate of the aircraft in the longitudinal motion is used to design the sliding surface. For optimization of the sliding surface, a Hamilton-Jacobi-Bellman (HJB) equation is formulated and it is solved through a numerical algorithm using a Generalized HJB (GHJB) equation and the Galerkin spectral method. The solution of this equation denotes a nonlinear sliding surface, on which the trajectory of the system approximately satisfies the optimality condition. Numerical simulation is performed for a nonlinear aircraft model with an optimized sliding surface and a simple linear sliding surface. The simulation result demonstrates that the proposed controller can be effectively applied to the longitudinal maneuver of an aircraft.

  3. Sliding mode control with PID sliding surface and experimental application to an electromechanical plant.

    PubMed

    Eker, Ilyas

    2006-01-01

    In this study, a sliding mode control system with a proportional+integral+derivative (PID) sliding surface is adopted to control the speed of an electromechanical plant. A robust sliding mode controller is derived so that the actual trajectory tracks the desired trajectory despite uncertainty, nonlinear dynamics, and external disturbances. The proposed sliding mode controller is chosen to ensure the stability of overall dynamics during the reaching phase and sliding phase. The stability of the system is guaranteed in the sense of the Lyapunov stability theorem. The chattering problem is overcome using a hyperbolic function for the sliding surface. Experimental results that are compared with the results of conventional PID verify that the proposed sliding mode controller can achieve favorable tracking performance, and it is robust with regard to uncertainties and disturbances.

  4. Sliding Over a Phase Transition

    NASA Astrophysics Data System (ADS)

    Tosatti, Erio; Benassi, Andrea; Vanossi, Andrea; Santoro, Giuseppe E.

    2011-03-01

    The frictional response experienced by a stick-slip slider when a phase transition occurs in the underlying solid substrate is a potentially exciting, poorly explored problem. We show, based on 2-dimensional simulations modeling the sliding of a nanotip, that indeed friction may be heavily affected by a continuous structural transition. First, friction turns nonmonotonic as temperature crosses the transition, peaking at the critical temperature Tc where fluctuations are strongest. Second, below Tc friction depends upon order parameter directions, and is much larger for those where the frictional slip can cause a local flip. This may open a route towards control of atomic scale friction by switching the order parameter direction by an external field or strain, with possible application to e.g., displacive ferroelectrics such as BaTi O3 , as well as ferro- and antiferro-distortive materials. Supported by project ESF FANAS/AFRI sponsored by the Italian Research Council (CNR).

  5. The jet of the BL Lacertae object PKS 2201+044: MAD near-IR adaptive optics observations and comparison with optical, radio and X-ray data

    NASA Astrophysics Data System (ADS)

    Liuzzo, E.; Falomo, R.; Treves, A.; Donato, D.; Sambruna, M.; Arcidiacono, C.; Giovannini, G.; Farinato, J.; Moretti, A.; Ragazzoni, R.; Diolaiti, E.; Lombini, M.; Brast, R.; Donaldson, R.; Kolb, J.; Marchetti, E.; Tordo, S.

    2011-04-01

    Context. Relativistic jets are a common feature of radio loud active galactic nuclei. Multifrequency observations are a unique tool to constrain their physics. Aims: We report on a detailed study of the properties of the jet of the nearby BL Lac object PKS 2201+044, one of the rare cases where the jet is detected from radio to X-rays. Methods: We use new adaptive optics near-IR observations of the source, obtained with the ESO multi-conjugated adaptive optics demonstrator (MAD) at the Very Large Telescope. These observations acquired in Ground-Layer Adaptive Optics mode are combined with images previously achieved by HST, VLA and Chandra to perform a morphological and photometric study of the jet. Results: We find a noticeable similarity in the morphology of the jet at radio, near-IR and optical wavelengths. We construct the spectral shape of the main knot of jet that appears dominated by synchrotron radiation. Conclusions: On the basis of the jet morphology and the weak lines spectrum we suggest that PKS 2201+044 belongs to the class of radio sources intermediate between FRIs and FRIIs.

  6. Terminal sliding mode tracking control for a class of SISO uncertain nonlinear systems.

    PubMed

    Chen, Mou; Wu, Qing-Xian; Cui, Rong-Xin

    2013-03-01

    In this paper, the terminal sliding mode tracking control is proposed for the uncertain single-input and single-output (SISO) nonlinear system with unknown external disturbance. For the unmeasured disturbance of nonlinear systems, terminal sliding mode disturbance observer is presented. The developed disturbance observer can guarantee the disturbance approximation error to converge to zero in the finite time. Based on the output of designed disturbance observer, the terminal sliding mode tracking control is presented for uncertain SISO nonlinear systems. Subsequently, terminal sliding mode tracking control is developed using disturbance observer technique for the uncertain SISO nonlinear system with control singularity and unknown non-symmetric input saturation. The effects of the control singularity and unknown input saturation are combined with the external disturbance which is approximated using the disturbance observer. Under the proposed terminal sliding mode tracking control techniques, the finite time convergence of all closed-loop signals are guaranteed via Lyapunov analysis. Numerical simulation results are given to illustrate the effectiveness of the proposed terminal sliding mode tracking control.

  7. Regulation of Blood Glucose Concentration in Type 1 Diabetics Using Single Order Sliding Mode Control Combined with Fuzzy On-line Tunable Gain, a Simulation Study.

    PubMed

    Dinani, Soudabeh Taghian; Zekri, Maryam; Kamali, Marzieh

    2015-01-01

    Diabetes is considered as a global affecting disease with an increasing contribution to both mortality rate and cost damage in the society. Therefore, tight control of blood glucose levels has gained significant attention over the decades. This paper proposes a method for blood glucose level regulation in type 1 diabetics. The control strategy is based on combining the fuzzy logic theory and single order sliding mode control (SOSMC) to improve the properties of sliding mode control method and to alleviate its drawbacks. The aim of the proposed controller that is called SOSMC combined with fuzzy on-line tunable gain is to tune the gain of the controller adaptively. This merit causes a less amount of control effort, which is the rate of insulin delivered to the patient body. As a result, this method can decline the risk of hypoglycemia, a lethal phenomenon in regulating blood glucose level in diabetics caused by a low blood glucose level. Moreover, it attenuates the chattering observed in SOSMC significantly. It is worth noting that in this approach, a mathematical model called minimal model is applied instead of the intravenously infused insulin-blood glucose dynamics. The simulation results demonstrate a good performance of the proposed controller in meal disturbance rejection and robustness against parameter changes. In addition, this method is compared to fuzzy high-order sliding mode control (FHOSMC) and the superiority of the new method compared to FHOSMC is shown in the results.

  8. Decoupling control based on terminal sliding mode and wavelet network for the speed and tension system of reversible cold strip rolling mill

    NASA Astrophysics Data System (ADS)

    Fang, Yiming; Liu, Le; Li, Jianxiong; Xu, Yanze

    2015-08-01

    To weaken the nonlinear coupling influences among the variables in the speed and tension system of reversible cold strip rolling mill, a novel dynamic decoupling control strategy is proposed based on nonsingular fast terminal sliding mode (NFTSM) and wavelet neural network (WNN). First, nonlinear disturbance observers are developed to counteract the mismatched uncertainties, and then input/output dynamic decoupling and linearisation for the speed and tension nonlinear coupling system are realised by utilising the inverse system theory. Second, nonsingular fast terminal sliding mode controller (NFTSMC) for each pseudo linear subsystem is presented based on backstepping and two-power reaching law, so as to improve the global convergence speed and robust stability of the system. Third, adaptive WNNs are used to approximate the uncertain items of the system, so as to improve the control precision of the speed and tension of reversible cold strip rolling mill. Theoretical analyses show that the NFTSMs satisfy reachability condition, the system error variables can converge to equilibrium point in finite time, and the resulting closed-loop system is globally asymptotically stable. Finally, simulation research is carried out on the speed and tension system of a 1422 mm reversible cold strip rolling mill by using the actual data, and results show the superiority of the proposed control strategy in comparison with the strategies of cascade PI, linear sliding mode control and internal model control.

  9. Regulation of Blood Glucose Concentration in Type 1 Diabetics Using Single Order Sliding Mode Control Combined with Fuzzy On-line Tunable Gain, a Simulation Study

    PubMed Central

    Dinani, Soudabeh Taghian; Zekri, Maryam; Kamali, Marzieh

    2015-01-01

    Diabetes is considered as a global affecting disease with an increasing contribution to both mortality rate and cost damage in the society. Therefore, tight control of blood glucose levels has gained significant attention over the decades. This paper proposes a method for blood glucose level regulation in type 1 diabetics. The control strategy is based on combining the fuzzy logic theory and single order sliding mode control (SOSMC) to improve the properties of sliding mode control method and to alleviate its drawbacks. The aim of the proposed controller that is called SOSMC combined with fuzzy on-line tunable gain is to tune the gain of the controller adaptively. This merit causes a less amount of control effort, which is the rate of insulin delivered to the patient body. As a result, this method can decline the risk of hypoglycemia, a lethal phenomenon in regulating blood glucose level in diabetics caused by a low blood glucose level. Moreover, it attenuates the chattering observed in SOSMC significantly. It is worth noting that in this approach, a mathematical model called minimal model is applied instead of the intravenously infused insulin–blood glucose dynamics. The simulation results demonstrate a good performance of the proposed controller in meal disturbance rejection and robustness against parameter changes. In addition, this method is compared to fuzzy high-order sliding mode control (FHOSMC) and the superiority of the new method compared to FHOSMC is shown in the results. PMID:26284169

  10. Whole slide imaging for educational purposes

    PubMed Central

    Pantanowitz, Liron; Szymas, Janusz; Yagi, Yukako; Wilbur, David

    2012-01-01

    Digitized slides produced by whole slide image scanners can be easily shared over a network or by transferring image files to optical or other data storage devices. Navigation of digitized slides is interactive and intended to simulate viewing glass slides with a microscope (virtual microscopy). Image viewing software permits users to edit, annotate, analyze, and easily share whole slide images (WSI). As a result, WSI have begun to replace the traditional light microscope, offering a myriad of opportunities for education. This article focuses on current applications of WSI in education and proficiency testing. WSI has been successfully explored for graduate education (medical, dental, and veterinary schools), training of pathology residents, as an educational tool in allied pathology schools (e.g., cytotechnology), for virtual tracking and tutoring, tele-education (tele-conferencing), e-learning, virtual workshops, at tumor boards, with interactive publications, and on examinations. WSI supports flexible and cost-effective distant learning and augments problem-oriented teaching, competency evaluation, and proficiency testing. WSI viewed on touchscreen displays and with tablet technology are especially beneficial for education. Further investigation is necessary to develop superior WSI applications that better support education and to design viewing stations with ergonomic tools that improve the WSI-human interface and navigation of virtual slides. Studies to determine the impact of training pathologists without exposure to actual glass slides are also needed. PMID:23372987

  11. SSP: Sketching Slide Presentations, a Syntactic Approach

    NASA Astrophysics Data System (ADS)

    Mas, Joan; Sanchez, Gemma; Lladós, Josep

    The design of a slide presentation is a creative process. In this process first, humans visualize in their minds what they want to explain. Then, they have to be able to represent this knowledge in an understandable way. There exists a lot of commercial software that allows to create our own slide presentations but the creativity of the user is rather limited. In this article we present an application that allows the user to create and visualize a slide presentation from a sketch. A slide may be seen as a graphical document or a diagram where its elements are placed in a particular spatial arrangement. To describe and recognize slides a syntactic approach is proposed. This approach is based on an Adjacency Grammar and a parsing methodology to cope with this kind of grammars. The experimental evaluation shows the performance of our methodology from a qualitative and a quantitative point of view. Six different slides containing different number of symbols, from 4 to 7, have been given to the users and they have drawn them without restrictions in the order of the elements. The quantitative results give an idea on how suitable is our methodology to describe and recognize the different elements in a slide.

  12. Pre-Linguistic Autism Diagnostic Observation Schedule Adapted for Older Individuals with Severe to Profound Mental Retardation: A Pilot Study

    ERIC Educational Resources Information Center

    Berument, Sibel Kazak; Starr, Elizabeth; Pickles, Andrew; Tomlins, Megan; Papanikolauou, Katerina; Lord, Catherine; Rutter, Michael

    2005-01-01

    The Autism Diagnostic Observational Schedule (ADOS) is a semi-structured observational scale developed to assess social interaction, communication and play in individuals who are suspected to have autism. Since the ADOS is not suitable to be used with severely or profoundly mentally retarded adolescents and adults with very limited language…

  13. The Earth surface slide movement at Soledad

    NASA Astrophysics Data System (ADS)

    Moreno, A.

    1986-11-01

    The Earth surface slide movement at Soledad is a mountain-slide type of movement. Estimations of the thickness of the layer which is moving range between 10 and 100 m. There is no proof that the movement is water induced, but it could be influenced by the water household. The slope of the slide area is H: D = 1: 2. The height difference in the moving area studied, according to this paper, is 1 km. The actual rate of movement is about 12 cm/yr.

  14. Rheological behavior of Slide Ring Gels.

    NASA Astrophysics Data System (ADS)

    Sharma, Vivek; Park, Jong Seung; Park, Jung O.; Srinivasarao, Mohan

    2006-03-01

    Slide ring gels were synthesized by chemically crosslinking, sparsely populated α-cyclodextrin (α-CD) present on the polyrotaxanes consisting of α-CD and polyethylene glycol (PEG). [1] Unlike physically or chemically crosslinked gels, slide ring gels are topological gels where crosslinks can slide along the chain. [2] We investigate the rheological behavior of these gels swollen in water and compare their viscoelastic properties to those of physical and chemical gels. We also study the equilibrium swelling behavior of these gels. [1] Okumura and Ito, Adv. Mater. 2001, 13, 485 [2] C. Zhao et al, J. Phys. Cond. Mat. 2005, 17, S2841

  15. Increase in friction force with sliding speed

    NASA Astrophysics Data System (ADS)

    Cross, Rod

    2005-09-01

    A block sliding down an inclined plane normally accelerates. However, if the friction force increases with speed, then the block can slide at a constant terminal speed in a manner similar to the fall of an object through a fluid. Measurements of the increase in the coefficient of friction for tennis ball cloth sliding on a smooth surface are described over speeds varying by a factor of 9000. For the low speed measurements, the ball cloth was attached to the bottom of a weighted box and pulled along a horizontal surface by a constant horizontal force. Results at higher speeds were obtained by bouncing a tennis ball off the surface.

  16. Evolution of the CRISPR-Cas adaptive immunity systems in prokaryotes: models and observations on virus-host coevolution.

    PubMed

    Koonin, Eugene V; Wolf, Yuri I

    2015-01-01

    CRISPR-Cas is an adaptive immunity system in prokaryotes that functions via a unique mechanism which involves incorporation of foreign DNA fragments into CRISPR arrays and subsequent utilization of transcripts of these inserts (known as spacers) as guide RNAs to cleave the cognate selfish element genome. Multiple attempts have been undertaken to explore the coevolution of viruses and microbial hosts carrying CRISPR-Cas using mathematical models that employ either systems of differential equations or an agent-based approach, or combinations thereof. Analysis of these models reveals highly complex co-evolutionary dynamics that ensues from the combination of the heritability of the CRISPR-mediated adaptive immunity with the existence of different degrees of immunity depending on the number of cognate spacers and the cost of carrying a CRISPR-Cas locus. Depending on the details of the models, a variety of testable, sometimes conflicting predictions have been made on the dependence of the degree of immunity and the benefit of maintaining CRISPR-Cas on the abundance and diversity of hosts and viruses. Some of these predictions have already been directly validated experimentally. In particular, both the reality of the virus-host arms race, with viruses escaping resistance and hosts reacquiring it through the capture of new spacers, and the fitness cost of CRISPR-Cas due to the curtailment of beneficial HGT have been reproduced in the laboratory. However, to test the predictions of the models more specifically, detailed studies of coevolving populations of microbes and viruses both in nature and in the laboratory are essential. Such analyses are expected to yield disagreements with the predictions of the current, oversimplified models and to trigger a new round of theoretical developments.

  17. Identification of mycobacterium tuberculosis in sputum smear slide using automatic scanning microscope

    NASA Astrophysics Data System (ADS)

    Rulaningtyas, Riries; Suksmono, Andriyan B.; Mengko, Tati L. R.; Saptawati, Putri

    2015-04-01

    Sputum smear observation has an important role in tuberculosis (TB) disease diagnosis, because it needs accurate identification to avoid high errors diagnosis. In development countries, sputum smear slide observation is commonly done with conventional light microscope from Ziehl-Neelsen stained tissue and it doesn't need high cost to maintain the microscope. The clinicians do manual screening process for sputum smear slide which is time consuming and needs highly training to detect the presence of TB bacilli (mycobacterium tuberculosis) accurately, especially for negative slide and slide with less number of TB bacilli. For helping the clinicians, we propose automatic scanning microscope with automatic identification of TB bacilli. The designed system modified the field movement of light microscope with stepper motor which was controlled by microcontroller. Every sputum smear field was captured by camera. After that some image processing techniques were done for the sputum smear images. The color threshold was used for background subtraction with hue canal in HSV color space. Sobel edge detection algorithm was used for TB bacilli image segmentation. We used feature extraction based on shape for bacilli analyzing and then neural network classified TB bacilli or not. The results indicated identification of TB bacilli that we have done worked well and detected TB bacilli accurately in sputum smear slide with normal staining, but not worked well in over staining and less staining tissue slide. However, overall the designed system can help the clinicians in sputum smear observation becomes more easily.

  18. Sliding bubble dynamics and the effects on surface heat transfer

    NASA Astrophysics Data System (ADS)

    Donnelly, B.; Robinson, A. J.; Delauré, Y. M. C.; Murray, D. B.

    2012-11-01

    An investigation into the effects of a single sliding air bubble on heat transfer from a submerged, inclined surface has been undertaken. Existing literature has shown that both vapour and gas bubbles can increase heat transfer rates from adjacent heated surfaces. However, the mechanisms involved are complex and dynamic and in some cases poorly understood. The present study utilises high speed, high resolution, infrared thermography and video photography to measure two dimensional surface heat transfer and three dimensional bubble position and shape. This provides a unique insight into the complex interactions at the heated surface. Bubbles of volume 0.05, 0.1, 0.2 and 0.4 ml were released onto a surface inclined at 30 degrees to horizontal. Results confirmed that sliding bubbles can enhance heat transfer rates up to a factor of 9 and further insight was gained about the mechanisms behind this phenomenon. The enhancement effects were observed over large areas and persisted for a long duration with the bubble exhibiting complex shape and path oscillations. It is believed that the periodic wake structure present behind the sliding bubble affects the bubble motion and is responsible for the heat transfer effects observed. The nature of this wake is proposed to be that of a chain of horseshoe vortices.

  19. Plastic strain arrangement in copper single crystals in sliding

    SciTech Connect

    Chumaevskii, Andrey V. Lychagin, Dmitry V.; Tarasov, Sergei Yu.

    2014-11-14

    Deformation of tribologically loaded contact zone is one of the wear mechanisms in spite of the fact that no mass loss may occur during this process. Generation of optimal crystallographic orientations of the grains in a polycrystalline materials (texturing) may cause hardening and reducing the deformation wear. To reveal the orientation dependence of an individual gain and simplify the task we use copper single crystals with the orientations of the compression axis along [111] and [110]. The plastic deformation was investigated by means of optical, scanning electron microscopy and EBSD techniques. It was established that at least four different zones were generated in the course of sliding test, such as non-deformed base metal, plastic deformation layer sliding, crystalline lattice reorientation layer and subsurface grain structure layer. The maximum plastic strain penetration depth was observed on [110]-single crystals. The minimum stability of [111]-crystals with respect to rotation deformation mode as well as activation of shear in the sliding contact plane provide for rotation deformation localization below the worn surface. The high-rate accumulation of misorientations and less strain penetration depth was observed on [111]-crystals as compared to those of [110]-oriented ones.

  20. Foam-filled cushions for sliding trays

    NASA Technical Reports Server (NTRS)

    Nahin, S. B.; Robb, P. H.

    1980-01-01

    Polytetrafluoroethylene tube filled with polyurethane foam forms low friction sliding surface that cushions vibrations and absorbs manufacturing tolerances and misalignment. Possible uses include packaging of components for shipping and seals for doors in lockers, cars, and refrigerators.

  1. Sliding scale insulin use: myth or insanity?

    PubMed

    Umpierrez, Guillermo E; Palacio, Andres; Smiley, Dawn

    2007-07-01

    Inpatient hyperglycemia in people with or without diabetes is associated with an increased risk of complications and mortality, a longer hospital stay, a higher admission rate to the intensive care unit, and higher hospitalization costs. Despite increasing evidence that supports intensive glycemic control in hospitalized patients, blood glucose control continues to be challenging, and sliding scale insulin coverage, a practice associated with limited therapeutic success, continues to be the most frequent insulin regimen in hospitalized patients. Sliding scale insulin has been in use for more than 80 years without much evidence to support its use as the standard of care. Several studies have revealed evidence of poor glycemic control and deleterious effects in sliding scale insulin use. To understand its wide use and acceptance, we reviewed the origin, advantages, and disadvantages of sliding scale insulin in the inpatient setting.

  2. Automated single-slide staining system

    NASA Technical Reports Server (NTRS)

    Mills, S. M.; Wilkins, J. R.

    1974-01-01

    Apparatus developed to Gram-stain single slides automatically is flexible enough to accommodate other types of staining procedures. Method frees operator and eliminates necessity for subjective evaluations as to length of staining or decolorizing time.

  3. Variations of the Sliding Ladder Problem

    ERIC Educational Resources Information Center

    Kapranidis, Stelios; Koo, Reginald

    2008-01-01

    This article takes another look at the sliding ladder problem that students meet in the study of related rates in calculus. Physically realistic situations with both constrained and understrained ladders are explored.

  4. The Foley Acoustic Wave Front Slides

    NASA Astrophysics Data System (ADS)

    Greenslade, Thomas B.

    2004-04-01

    In 1912 Arthur L. Foley of Indiana University published an article in Physical Review about his technique for photographing acoustic wave fronts. Subsequently, the Central Scientific Company published a series of glass lantern slides of his illustrations. These have been unavailable for about 60 years. Here I discuss how Foley made his slides and give examples of use to the present-day physics teacher.

  5. WTP Pretreatment Facility Potential Design Deficiencies--Sliding Bed and Sliding Bed Erosion Assessment

    SciTech Connect

    Hansen, E. K.

    2015-05-06

    This assessment is based on readily available literature and discusses both Newtonian and non-Newtonian slurries with respect to sliding beds and erosion due to sliding beds. This report does not quantify the size of the sliding beds or erosion rates due to sliding beds, but only assesses if they could be present. This assessment addresses process pipelines in the Pretreatment (PT) facility and the high level waste (HLW) transfer lines leaving the PT facility to the HLW vitrification facility concentrate receipt vessel.

  6. Observer-based adaptive fuzzy-neural control for a class of uncertain nonlinear systems with unknown dead-zone input.

    PubMed

    Liu, Yan-Jun; Zhou, Ning

    2010-10-01

    Based on the universal approximation property of the fuzzy-neural networks, an adaptive fuzzy-neural observer design algorithm is studied for a class of nonlinear SISO systems with both a completely unknown function and an unknown dead-zone input. The fuzzy-neural networks are used to approximate the unknown nonlinear function. Because it is assumed that the system states are unmeasured, an observer needs to be designed to estimate those unmeasured states. In the previous works with the observer design based on the universal approximator, when the dead-zone input appears it is ignored and the stability of the closed-loop system will be affected. In this paper, the proposed algorithm overcomes the affections of dead-zone input for the stability of the systems. Moreover, the dead-zone parameters are assumed to be unknown and will be adjusted adaptively as well as the sign function being introduced to compensate the dead-zone. With the aid of the Lyapunov analysis method, the stability of the closed-loop system is proven. A simulation example is provided to illustrate the feasibility of the control algorithm presented in this paper.

  7. The Louisiana Slide Library; A Humanities Program. Bulletin 1755.

    ERIC Educational Resources Information Center

    Louisiana Council for Music and Performing Arts, New Orleans.

    The Louisiana Slide Library is an extensive collection of slides, lectures, and tapes designed for use in the arts, the humanities, social and ethnic studies, languages, home economics, careers, crafts, and special education. This bibliography lists these slide sets and indicates the grade level intended for each set and the number of slides in…

  8. Ornamental Annual Plants and Their Uses. Slide Script.

    ERIC Educational Resources Information Center

    Still, Steven

    This slide script, part of a series of slide scripts designed for use in vocational agriculture classes, deals with ornamental annual plants and their uses. Included in the script are narrations for use with a total of 254 slides illustrating 97 different plants. At least two slides are provided for each plant: one shows the growth habits of the…

  9. fMRI Adaptation between Action Observation and Action Execution Reveals Cortical Areas with Mirror Neuron Properties in Human BA 44/45

    PubMed Central

    de la Rosa, Stephan; Schillinger, Frieder L.; Bülthoff, Heinrich H.; Schultz, Johannes; Uludag, Kamil

    2016-01-01

    Mirror neurons (MNs) are considered to be the supporting neural mechanism for action understanding. MNs have been identified in monkey’s area F5. The identification of MNs in the human homolog of monkeys’ area F5 Broadmann Area 44/45 (BA 44/45) has been proven methodologically difficult. Cross-modal functional MRI (fMRI) adaptation studies supporting the existence of MNs restricted their analysis to a priori candidate regions, whereas studies that failed to find evidence used non-object-directed (NDA) actions. We tackled these limitations by using object-directed actions (ODAs) differing only in terms of their object directedness in combination with a cross-modal adaptation paradigm and a whole-brain analysis. Additionally, we tested voxels’ blood oxygenation level-dependent (BOLD) response patterns for several properties previously reported as typical MN response properties. Our results revealed 52 voxels in left inferior frontal gyrus (IFG; particularly BA 44/45), which respond to both motor and visual stimulation and exhibit cross-modal adaptation between the execution and observation of the same action. These results demonstrate that part of human IFG, specifically BA 44/45, has BOLD response characteristics very similar to monkey’s area F5. PMID:26973496

  10. On damping characteristics of frictional hysteresis in pre-sliding range

    NASA Astrophysics Data System (ADS)

    Ruderman, Michael; Iwasaki, Makoto

    2016-06-01

    Frictional hysteresis at relative motion in the pre-sliding range is considered. This effect is characterized by an elasto-plastic interaction, and that on the micro-scale, between two rubbing surfaces in contact that gives rise to nonlinear friction force. The pre-sliding friction force yields hysteresis in displacement. In this study, the damping characteristics of frictional hysteresis are analyzed. It is worth noting that we exclude the viscous damping mechanisms and focus on the pure hysteresis damping to be accounted in the friction modeling. The general properties of pre-sliding friction hysteresis are demonstrated and then compared with the limit case of discontinuous Coulomb friction. Further we consider two advanced dynamic friction models, LuGre and Maxwell-slip, so as demonstrate their damping properties and convergence of the motion system to equilibrium state. Experimental observations of the free motion in pre-sliding range are also shown and discussed.

  11. Plastic deformation and wear process at a surface during unlubricated sliding

    NASA Technical Reports Server (NTRS)

    Yamamoto, T.; Buckley, D. H.

    1982-01-01

    The plastic deformation and wear of a 304 stainless steel surface sliding against an aluminum oxide rider with a spherical surface (the radius of curvature: 1.3 cm) were observed by using scanning electron and optical microscopes. Experiments were conducted in a vacuum of one million Pa and in an environment of fifty thousandth Pa of chlorine gas at 25 C. The load was 500 grams and the sliding velocity was 0.5 centimeter per second. The deformed surface layer which accumulates and develops successively is left behind the rider, and step shaped proturbances are developed even after single pass sliding under both environmental conditions. A fully developed surface layer is gradually torn off leaving a characteristic pattern. The mechanism for tearing away of the surface layer from the contact area and sliding track contour is explained assuming the simplified process of material removal based on the adhesion theory for the wear of materials.

  12. Compact, Automated Centrifugal Slide-Staining System

    NASA Technical Reports Server (NTRS)

    Feeback, Daniel L.; Clarke, Mark S. F.

    2004-01-01

    The Directional Acceleration Vector-Driven Displacement of Fluids (DAVD-DOF) system, under development at the time of reporting the information for this article, would be a relatively compact, automated, centrifugally actuated system for staining blood smears and other microbiological samples on glass microscope slides in either a microgravitational or a normal Earth gravitational environment. The DAVD-DOF concept is a successor to the centrifuge-operated slide stainer (COSS) concept, which was reported in Slide-Staining System for Microgravity or Gravity (MSC-22949), NASA Tech Briefs, Vol. 25, No. 1 (January, 2001), page 64. The COSS includes reservoirs and a staining chamber that contains a microscope slide to which a biological sample is affixed. The staining chamber is sequentially filled with and drained of staining and related liquids from the reservoirs by use of a weighted plunger to force liquid from one reservoir to another at a constant level of hypergravity maintained in a standard swing-bucket centrifuge. In the DAVD-DOF system, a staining chamber containing a sample would also be sequentially filled and emptied, but with important differences. Instead of a simple microscope slide, one would use a special microscope slide on which would be fabricated a network of very small reservoirs and narrow channels connected to a staining chamber (see figure). Unlike in the COSS, displacement of liquid would be effected by use of the weight of the liquid itself, rather than the weight of a plunger.

  13. Characterization of tissue and slide artifacts from automated embedding systems.

    PubMed

    Goldberg, Matthew S; Wetherington, Sarah J; Susa, Joseph S; Wickless, Scott C; Cockerell, Clay J

    2015-11-01

    With recent technological advances and cost reductions, automated embedding systems are rapidly becoming routine in the processing of skin biopsy specimens. The efficiency advantages of this technique are due in part to the use of patented sectionable cassettes that hold formalin-fixed tissue from the time of grossing through tissue sectioning. In this process, the final paraffin block contains both the tissue and the cassette, which are sectioned and stained in unison. Here, we report the multiple tissue and slide artifacts commonly seen with automated embedding systems that are unique to this method of tissue processing. The most frequently observed tissue changes are patterned molding of the biopsy specimen around the cassette material. The most common slide artifacts are due to the presence of geometrically shaped polarizable cassette material adjacent to or overlying the stained tissue. As many of these artifacts strongly resemble the shapes seen in the classic 1980s video game, Tetris, we propose the term of Tetris-like artifacts for these findings. Although we remain confident that use of an automated embedding system does not decrease diagnostic reliability, increased familiarity with the standard appearance of slides processed using this technique will help avoid confusion when evaluating these cases.

  14. Sliding Mode Control Applied to Reconfigurable Flight Control Design

    NASA Technical Reports Server (NTRS)

    Hess, R. A.; Wells, S. R.; Bacon, Barton (Technical Monitor)

    2002-01-01

    Sliding mode control is applied to the design of a flight control system capable of operating with limited bandwidth actuators and in the presence of significant damage to the airframe and/or control effector actuators. Although inherently robust, sliding mode control algorithms have been hampered by their sensitivity to the effects of parasitic unmodeled dynamics, such as those associated with actuators and structural modes. It is known that asymptotic observers can alleviate this sensitivity while still allowing the system to exhibit significant robustness. This approach is demonstrated. The selection of the sliding manifold as well as the interpretation of the linear design that results after introduction of a boundary layer is accomplished in the frequency domain. The design technique is exercised on a pitch-axis controller for a simple short-period model of the High Angle of Attack F-18 vehicle via computer simulation. Stability and performance is compared to that of a system incorporating a controller designed by classical loop-shaping techniques.

  15. Sliding drops across alternating hydrophobic and hydrophilic stripes.

    PubMed

    Sbragaglia, M; Biferale, L; Amati, G; Varagnolo, S; Ferraro, D; Mistura, G; Pierno, M

    2014-01-01

    We perform a joint numerical and experimental study to systematically characterize the motion of 30 μl drops of pure water and of ethanol in water solutions, sliding over a periodic array of alternating hydrophobic and hydrophilic stripes with a large wettability contrast and a typical width of hundreds of microns. The fraction of the hydrophobic areas has been varied from about 20% to 80%. The effects of the heterogeneous patterning can be described by a renormalized value of the critical Bond number, i.e., the critical dimensionless force needed to depin the drop before it starts to move. Close to the critical Bond number we observe a jerky motion characterized by an evident stick-slip dynamics. As a result, dissipation is strongly localized in time, and the mean velocity of the drops can easily decrease by an order of magnitude compared to the sliding on the homogeneous surface. Lattice Boltzmann numerical simulations are crucial for disclosing to what extent the sliding dynamics can be deduced from the computed balance of capillary, viscous, and body forces by varying the Bond number, the surface composition, and the liquid viscosity. Beyond the critical Bond number, we characterize both experimentally and numerically the dissipation inside the droplet by studying the relation between the average velocity and the applied volume forces.

  16. RTTOV-gb - Adapting the fast radiative transfer model RTTOV for the assimilation of ground-based microwave radiometer observations

    NASA Astrophysics Data System (ADS)

    De Angelis, Francesco; Cimini, Domenico; Hocking, James; Martinet, Pauline; Kneifel, Stefan

    2016-04-01

    The Planetary Boundary Layer (PBL) is the single most important under-sampled part of the atmosphere. According to the WMO Statement Of Guidance For Global Numerical Weather Prediction (NWP), temperature and humidity profiles (in cloudy areas) are among the four critical atmospheric variables not adequately measured in the PBL. Ground-based microwave radiometers (MWR) provide temperature and humidity profiles in both clear- and cloudy-sky conditions with high temporal resolution and low-to-moderate vertical resolution, with information mostly residing in the PBL. Ground-based MWR offer to bridge this observational gap by providing continuous temperature and humidity information in the PBL. The MWR data assimilation into NWP models may be particularly important in nowcasting and severe weather initiation. The assimilation of thermodynamic profiles retrieved from MWR data has been recently experimented, but a way to possibly increase the impact is to directly assimilate measured radiances instead of retrieved profiles. The assimilation of observed radiances in a variational scheme requires the following tools: (i) a fast radiative transfer (RT) model to compute the simulated radiances at MWR channels from the NWP model fields (ii) the partial derivatives (Jacobians) of the fast radiative transfer model with respect to control variables to optimize the distances of the atmospheric state from both the first guess and the observations. Such a RT model is available from the EUMETSAT NWPSAF (Numerical Weather Prediction Satellite Application Facility) and well accepted in the NWP community: RTTOV. This model was developed for nadir-viewing passive visible, infrared, and microwave satellite radiometers, spectrometers and interferometers. It has been modified to handle ground-based microwave radiometer observations. This version of RTTOV, called RTTOV-gb, provides the tools needed to exploit ground-based upward looking MWR brightness temperatures into NWP variational data

  17. Frictional sliding of biotite gouge under hydrothermal conditions

    NASA Astrophysics Data System (ADS)

    Lu, Z.; He, C.

    2012-12-01

    -brittle viscous flow. The evolution from strong viscous flow to frictional behavior is clearly exhibited by the experiments at 500°C and 600°C, and it seems that the sliding behavior at 400°C is also on the same trend though frictional behavior did not occur in the limited displacement in our experiment. It is worth noting that the strong viscous flow here is found to be related only to supercritical water conditions. Microstructural observations show that extensively developed basal slips and kinking bands in the deformed samples are the major deformation mechanism for the short-lived viscous flow at temperatures of 400-600°C. With the results of our experiments as a possible constraint on mechanical behavior of deep portion of fault zones, it seems that occurrence of biotite may reduce strengths of shear zones to levels far below those of the stronger framework minerals. Moreover, the trend of transition from semi-brittle viscous flow to frictional sliding for temperature over 400°C and the stick-slip behavior at 500 and 600°C suggest that unstable slip nucleation may be possible in the deep portion of biotite-rich fault zones provided frictional sliding is made possible by super-hydrostatic pore pressure.

  18. The influence of imposed normal vibrations on the frictional sliding along the fault

    NASA Astrophysics Data System (ADS)

    Karachevtseva, Iuliia; Dyskin, Arcady; Pasternak, Elena

    2016-04-01

    Sliding over discontinuities (faults, fractures) in the stable state is prevented by friction. However, the faults are continuously subjected to variations in normal stress and can produce sliding over initially stable fractures/interfaces. In the Earth's crust the normal oscillations can be produced by tidal stresses or by the seismic waves generated by other seismic events. This is associated with the earthquake triggering and leading to a stick-slip sliding. It is conventionally assumed that the mechanism of stick-slip over geomaterials lies in intermittent change between static and kinetic friction and the rate dependence of the friction coefficient. The formulation of the friction law on geological faults is the key element in the modelling of earthquakes. We investigate the effects of imposed normal vibrations on steady sliding and stick-slip regimes and analyse the dynamics of system with different friction modelling. For this purpose we consider a simple spring-block model introduced by Burridge and Knopoff. The results show that a model exhibits different behaviour in the frictional sliding with constant and nonlinear friction. It is important to note, that a block-spring model can produce oscillations in the velocity of sliding that is the stick-slip like behaviour even when the friction coefficient is constant. The effect of force reduction is observed under the influence of harmonic vertical vibrations. The rate-dependent friction creates more complex pattern of oscillations.

  19. Internal models in sensorimotor integration: perspectives from adaptive control theory.

    PubMed

    Tin, Chung; Poon, Chi-Sang

    2005-09-01

    Internal models and adaptive controls are empirical and mathematical paradigms that have evolved separately to describe learning control processes in brain systems and engineering systems, respectively. This paper presents a comprehensive appraisal of the correlation between these paradigms with a view to forging a unified theoretical framework that may benefit both disciplines. It is suggested that the classic equilibrium-point theory of impedance control of arm movement is analogous to continuous gain-scheduling or high-gain adaptive control within or across movement trials, respectively, and that the recently proposed inverse internal model is akin to adaptive sliding control originally for robotic manipulator applications. Modular internal models' architecture for multiple motor tasks is a form of multi-model adaptive control. Stochastic methods, such as generalized predictive control, reinforcement learning, Bayesian learning and Hebbian feedback covariance learning, are reviewed and their possible relevance to motor control is discussed. Possible applicability of a Luenberger observer and an extended Kalman filter to state estimation problems-such as sensorimotor prediction or the resolution of vestibular sensory ambiguity-is also discussed. The important role played by vestibular system identification in postural control suggests an indirect adaptive control scheme whereby system states or parameters are explicitly estimated prior to the implementation of control. This interdisciplinary framework should facilitate the experimental elucidation of the mechanisms of internal models in sensorimotor systems and the reverse engineering of such neural mechanisms into novel brain-inspired adaptive control paradigms in future.

  20. Compensation of significant parametric uncertainties using sliding mode online learning

    NASA Astrophysics Data System (ADS)

    Schnetter, Philipp; Kruger, Thomas

    An augmented nonlinear inverse dynamics (NID) flight control strategy using sliding mode online learning for a small unmanned aircraft system (UAS) is presented. Because parameter identification for this class of aircraft often is not valid throughout the complete flight envelope, aerodynamic parameters used for model based control strategies may show significant deviations. For the concept of feedback linearization this leads to inversion errors that in combination with the distinctive susceptibility of small UAS towards atmospheric turbulence pose a demanding control task for these systems. In this work an adaptive flight control strategy using feedforward neural networks for counteracting such nonlinear effects is augmented with the concept of sliding mode control (SMC). SMC-learning is derived from variable structure theory. It considers a neural network and its training as a control problem. It is shown that by the dynamic calculation of the learning rates, stability can be guaranteed and thus increase the robustness against external disturbances and system failures. With the resulting higher speed of convergence a wide range of simultaneously occurring disturbances can be compensated. The SMC-based flight controller is tested and compared to the standard gradient descent (GD) backpropagation algorithm under the influence of significant model uncertainties and system failures.

  1. On a model of frictional sliding

    NASA Astrophysics Data System (ADS)

    Estrin, Y.; Bréchet, Y.

    1996-10-01

    A model of frictional sliding with an N-shaped curve for the sliding velocity dependence of the coefficient of friction is considered. This type of friction law is shown to be related to dynamic i.e., velocity dependent ‘ageing’ of asperity junctions. Mechanisms of ‘ageing’ for ductile (Bowden-Tabor) and brittle (Byerlee) materials, though different in nature, lead to qualitatively similar N-shaped velocity dependencies of the coefficient of friction. Estimates for the velocities limiting the range of negative velocity sensitivity of the coefficient of friction are obtained for the ductile case and—albeit with a lesser degree of reliability—for the brittle one. It is shown by linear stability analysis that discontinuous sliding (stick-slip) is associated with the descending portion of the N-shaped curve. An instability criterion is obtained. An expression for the period of the attendant relaxation oscillations of the sliding velocity is given in terms of the calculated velocity dependence of the coefficient of friction. It is suggested that the micromechanically motivated friction law proposed should be used in models of earthquakes due to discontinuous frictional sliding on a crustal fault.

  2. Resistance to Sliding on Atomic Scales

    NASA Technical Reports Server (NTRS)

    Dominik, C.; Tielens, A.; Cuzzi, Jeffrey (Technical Monitor)

    1995-01-01

    The structure and stability of agglomerates of micron-sized particles is determined by the mechanical properties of the individual contacts between the constituent particles. In this paper we study the possibility of aggregate rearrangements by sliding. Since the contacts between (sub)micron particles are only a few hundred atoms in diameter, processes on atomic levels will play the dominating roll. We study a theoretical model of sliding friction for surfaces that are either flat or contain steps in their grids. The results show that sliding over flat surfaces may produce a large range of friction coefficients, including zero if the adhesive forces are small compared to the binding forces inside a body. However, both grid alignment and steps in the surface will lead to high values for friction. These processes combined virtually eliminate the possibility of sliding in a collision of two (sub)micron sized particles at velocities low enough for sticking to occur. On the other hand we show that in collisions between aggregates sliding may be an important factor for energy dissipation and compaction.

  3. Theory of sliding-mode triboelectric nanogenerators.

    PubMed

    Niu, Simiao; Liu, Ying; Wang, Sihong; Lin, Long; Zhou, Yu Sheng; Hu, Youfan; Wang, Zhong Lin

    2013-11-20

    The triboelectric nanogenerator (TENG) is a powerful approach toward new energy technology, especially for portable electronics. A theoretical model for the sliding-mode TENG is presented in this work. The finite element method was utilized to characterize the distributions of electric potential, electric field, and charges on the metal electrodes of the TENG. Based on the FEM calculation, the semi-analytical results from the interpolation method and the analytical V-Q-x relationship are built to study the sliding-mode TENG. The analytical V-Q-x equation is validated through comparison with the semi-analytical results. Furthermore, based on the analytical V-Q-x equation, dynamic output performance of sliding-mode TENG is calculated with arbitrary load resistance, and good agreement with experimental data is achieved. The theory presented here is a milestone work for in-depth understanding of the working mechanism of the sliding-mode TENG, and provides a theoretical basis for further enhancement of the sliding-mode TENG for both energy scavenging and self-powered sensor applications.

  4. Geometrical and hydrogeological impact on the behaviour of deep-seated rock slides during reservoir impoundment

    NASA Astrophysics Data System (ADS)

    Lechner, Heidrun; Zangerl, Christian

    2015-04-01

    Given that there are still uncertainties regarding the deformation and failure mechanisms of deep-seated rock slides this study concentrates on key factors that influence the behaviour of rock slides in the surrounding of reservoirs. The focus is placed on the slope geometry, hydrogeology and kinematics. Based on numerous generic rock slide models the impacts of the (i) rock slide geometry, (ii) reservoir impoundment and level fluctuations, (iii) seepage and buoyancy forces and (iv) hydraulic conductivity of the rock slide mass and the basal shear zone are examined using limit equilibrium approaches. The geometry of many deep-seated rock slides in metamorphic rocks is often influenced by geological structures, e.g. fault zones, joints, foliation, bedding planes and others. With downslope displacement the rock slide undergoes a change in shape. Several observed rock slides in an advanced stage show a convex, bulge-like topography at the foot of the slope and a concave topography in the middle to upper part. Especially, the situation of the slope toe plays an important role for stability. A potentially critical situation can result from a partially submerged flat slope toe because the uplift due to water pressure destabilizes the rock slide. Furthermore, it is essential if the basal shear zone daylights at the foot of the slope or encounters alluvial or glacial deposits at the bottom of the valley, the latter having a buttressing effect. In this study generic rock slide models with a shear zone outcropping at the slope toe are established and systematically analysed using limit equilibrium calculations. Two different kinematic types are modelled: (i) a translational or planar and (ii) a rotational movement behaviour. Questions concerning the impact of buoyancy and pore pressure forces that develop during first time impoundment are of key interest. Given that an adverse effect on the rock slide stability is expected due to reservoir impoundment the extent of

  5. Better slides needed at AGU Meetings

    NASA Astrophysics Data System (ADS)

    Jacobson, Randall S.

    Recent AGU meetings show a dangerous trend in the quality of presentations. A fair percentage of slides used during oral presentations consisted of a black background and colored lines and/or words for data. Such slides are illegible and serve to undercut the speaker's points by not demonstrating the data clearly.A typical example consisted of dark red, dark blue, and green data on a black background. Even the author had difficulty in pointing out the data using his light arrow. Line drawings, in particular, should not use colors, but instead use high-contrast white-on-black for the following reasons: dark colors on black backgrounds provide little contrast, making it difficult to discern patterns; people who are colorblind are at a disadvantage; and the same information can be obtained using a variety of line weights (dotdash, solid, dotted, etc.) with single color slides.

  6. NEMD simulations for ductile metal sliding

    SciTech Connect

    Hammerberg, James E; Germann, Timothy C; Ravelo, Ramon J; Holian, Brad L

    2011-01-31

    We have studied the sliding behavior for a 19 M Al(110)/Al(110) defective crystal at 15 GPa as a function of relative sliding velocity. The general features are qualitatively similar to smaller scale (1.4 M) atom simulations for Al(111)/Al(110) nondefective single crystal sliding. The critical velocity, v{sub c}, is approximately the same for the defective crystal as the size scaled v{sub c}. The lower velocity tangential force is depressed relative to the perfect crystal. The critical temperature, T*, is depressed relative to the perfect crystal. These conclusions are consistent with a lower value for f{sub c} for the defective crystal. The detailed features of structural transformation and the high velocity regime remain to be mapped.

  7. Newly recognized submarine slide complexes in the southern California Bight

    NASA Astrophysics Data System (ADS)

    Conrad, J. E.; Lee, H. J.; Edwards, B. D.; McGann, M.; Sliter, R. W.

    2012-12-01

    New high-resolution bathymetric and seismic-reflection surveys have imaged large (<0.5 km3) submarine landslides offshore southern California that have not been previously recognized in the Borderland. The new data show several large slides or slide complexes that include: 1) a slide complex consisting of numerous (>7) individual overlapping slides along the western margin of Santa Cruz Basin (SCB slide); 2) a series of slumps and slide scars on the slope south of San Pedro shelf (SPS slide); and 3) a slope failure along the shelf edge in northern San Diego County, termed the Del Mar slide. The SCB slide complex extends for 30 km along the western slope of Santa Cruz Basin, with debris lobes extending 5-8 km into the basin. Head scarps of some of these slides are 50-75 m high. The SPS slide complex also appears to consist of multiple slides, which roughly parallel the Palos Verdes Fault and the San Gabriel Canyon submarine channel on the shelf edge and slope south of San Pedro shelf. Slide deposits associated with this complex are only partially mapped due to limited high-resolution bathymetric coverage, but extend to the south in the area SW of Lasuen Knoll. Seismic-reflection profiles show that some of these deposits are up to 20 m thick. The Del Mar slide is located about 10 km north of La Jolla Canyon and extends about 6 km along the shelf edge. The head scarp lies along the trend of a branch of the Rose Canyon Fault Zone. Radiocarbon ages of sediment overlying this slide indicate the Del Mar slide is approximately 12-16 ka. These large slide complexes have several characteristics in common. Nearly all occur in areas of tectonic uplift. All of the complexes show evidence of recurrent slide activity, exhibiting multiple headwall scarps and debris lobes, and where available, high-resolution seismic-reflection profiles of these slide areas provide evidence of older, buried mass transport deposits. Assuming typical sedimentation rates, the recurrence interval of

  8. Optimal second order sliding mode control for nonlinear uncertain systems.

    PubMed

    Das, Madhulika; Mahanta, Chitralekha

    2014-07-01

    In this paper, a chattering free optimal second order sliding mode control (OSOSMC) method is proposed to stabilize nonlinear systems affected by uncertainties. The nonlinear optimal control strategy is based on the control Lyapunov function (CLF). For ensuring robustness of the optimal controller in the presence of parametric uncertainty and external disturbances, a sliding mode control scheme is realized by combining an integral and a terminal sliding surface. The resulting second order sliding mode can effectively reduce chattering in the control input. Simulation results confirm the supremacy of the proposed optimal second order sliding mode control over some existing sliding mode controllers in controlling nonlinear systems affected by uncertainty.

  9. Develop and Manufacture an airlock sliding tray

    SciTech Connect

    Lawton, Cindy M.

    2014-02-26

    Objective: The goal of this project is to continue to develop an airlock sliding tray and then partner with an industrial manufacturing company for production. The sliding tray will be easily installed into and removed from most glovebox airlocks in a few minutes. Technical Approach: A prototype of a sliding tray has been developed and tested in the LANL cold lab and 35 trays are presently being built for the plutonium facility (PF-4). The current, recently approved design works for a 14-inch diameter round airlock and has a tray length of approximately 20 inches. The grant will take the already tested and approved round technology and design for the square airlock. These two designs will be suitable for the majority of the existing airlocks in the multitude of DOE facilities. Partnering with an external manufacturer will allow for production of the airlock trays at a much lower cost and increase the availability of the product for all DOE sites. Project duration is estimated to be 12-13 months. Benefits: The purpose of the airlock sliding trays is fourfold: 1) Mitigate risk of rotator cuff injuries, 2) Improve ALARA, 3) Reduce risk of glovebox glove breaches and glove punctures, and 4) Improve worker comfort. I have had the opportunity to visit many other DOE facilities including Savannah, Y-12, ORNL, Sandia, and Livermore for assistance with ergonomic problems and/or injuries. All of these sites would benefit from the airlock sliding tray and I can assume all other DOE facilities with gloveboxes built prior to 1985 could also use the sliding trays.

  10. Railgun rail gouging by hypervelocity sliding contact

    SciTech Connect

    Barker, L.M.; Trucano, T.G. ); Susoeff, A.R. )

    1989-01-01

    A description is given of a recently resolved mechanisms of gouging which occurs during hypervelocity sliding contact between two materials. A parameter study based on computer modeling of the gouging mechanism is presented in which gouging velocity thresholds are determined for several combinations of sliding materials. Materials which can gouge each other are found to do so only within a certain range of velocities. Related calculations of gaseous material ahead of railgun projectiles are also presented. Gun bore gouging experience with the Lawrence Livermore National Laboratory railgun project is reviewed.

  11. Railgun rail gouging by hypervelocity sliding contact

    SciTech Connect

    Barker, L.M.; Trucano, T.G.; Susoeff, A.R.

    1988-01-01

    A description is given of a recently resolved mechanism of gouging which occurs during hypervelocity sliding contact between two materials. A parameter study based on computer modelling of the gouging mechanism is presented in which gouging velocity thresholds are determined for several combinations of sliding materials. Materials which can gouge each other are found to do so only within a certain range of velocities. Related calculations of gaseous material ahead of railgun projectiles are also presented. Gun bore gouging experience with the Lawrence Livermore National Laboratory railgun project is reviewed.

  12. Sliding Window Generalized Kernel Affine Projection Algorithm Using Projection Mappings

    NASA Astrophysics Data System (ADS)

    Slavakis, Konstantinos; Theodoridis, Sergios

    2008-12-01

    Very recently, a solution to the kernel-based online classification problem has been given by the adaptive projected subgradient method (APSM). The developed algorithm can be considered as a generalization of a kernel affine projection algorithm (APA) and the kernel normalized least mean squares (NLMS). Furthermore, sparsification of the resulting kernel series expansion was achieved by imposing a closed ball (convex set) constraint on the norm of the classifiers. This paper presents another sparsification method for the APSM approach to the online classification task by generating a sequence of linear subspaces in a reproducing kernel Hilbert space (RKHS). To cope with the inherent memory limitations of online systems and to embed tracking capabilities to the design, an upper bound on the dimension of the linear subspaces is imposed. The underlying principle of the design is the notion of projection mappings. Classification is performed by metric projection mappings, sparsification is achieved by orthogonal projections, while the online system's memory requirements and tracking are attained by oblique projections. The resulting sparsification scheme shows strong similarities with the classical sliding window adaptive schemes. The proposed design is validated by the adaptive equalization problem of a nonlinear communication channel, and is compared with classical and recent stochastic gradient descent techniques, as well as with the APSM's solution where sparsification is performed by a closed ball constraint on the norm of the classifiers.

  13. Percolation, sliding, localization and relaxation in topologically closed circuits

    PubMed Central

    Hurowitz, Daniel; Cohen, Doron

    2016-01-01

    Considering a random walk in a random environment in a topologically closed circuit, we explore the implications of the percolation and sliding transitions for its relaxation modes. A complementary question regarding the “delocalization” of eigenstates of non-hermitian Hamiltonians has been addressed by Hatano, Nelson, and followers. But we show that for a conservative stochastic process the implied spectral properties are dramatically different. In particular we determine the threshold for under-damped relaxation, and observe “complexity saturation” as the bias is increased. PMID:26961586

  14. A study of grain boundary sliding in copper with and without an addition of phosphorus

    NASA Astrophysics Data System (ADS)

    Pettersson, Kjell

    2010-10-01

    Copper will be used as a corrosion barrier in the storage of high level nuclear waste. In order to improve the creep fracture properties of the material it will contain 30-50 ppm of phosphorus, OFP copper as opposed to OF copper without P. It has been suggested that the phosphorus impedes grain boundary sliding in copper and recently a quantitative theory based on this idea has shown that there is no risk for creep-brittle fracture of OFP copper under waste storage conditions. In order to verify the basis of this theory grain boundary sliding has been investigated in copper with and without a P addition. The method has been to examine intentionally scratched surfaces of tensile specimens tension tested to plastic strains of 1%, 2% and 4% at 150 and 200 °C. After testing specimen surfaces have been examined in SEM and sliding distances have been measured as in-surface displacement of scratches. The results have been plotted as distribution functions where the fraction of slides smaller than a given value is plotted versus sliding distance. The result is that in most cases the distribution functions for OF and OFP copper overlap. In a small number of cases there is a tendency that less sliding has occurred in OFP copper. The overall conclusion is however that although there may be a slight difference between the materials with regard to grain boundary sliding it is not large enough to explain the observed difference in creep brittleness. Tension tests to fracture in the temperature range 100-200 °C show that the tensile properties of the two copper qualities are more or less identical until intergranular cracking starts in the OF copper. Then the flow stress decreases in comparison with OFP. It is suggested that at least part of the observed differences in creep strength between the two coppers may be due to the effect of intergranular cracking.

  15. Controlling chaos based on a novel intelligent integral terminal sliding mode control in a rod-type plasma torch

    NASA Astrophysics Data System (ADS)

    Safa, Khari; Zahra, Rahmani; Behrooz, Rezaie

    2016-05-01

    An integral terminal sliding mode controller is proposed in order to control chaos in a rod-type plasma torch system. In this method, a new sliding surface is defined based on a combination of the conventional sliding surface in terminal sliding mode control and a nonlinear function of the integral of the system states. It is assumed that the dynamics of a chaotic system are unknown and also the system is exposed to disturbance and unstructured uncertainty. To achieve a chattering-free and high-speed response for such an unknown system, an adaptive neuro-fuzzy inference system is utilized in the next step to approximate the unknown part of the nonlinear dynamics. Then, the proposed integral terminal sliding mode controller stabilizes the approximated system based on Lyapunov’s stability theory. In addition, a Bee algorithm is used to select the coefficients of integral terminal sliding mode controller to improve the performance of the proposed method. Simulation results demonstrate the improvement in the response speed, chattering rejection, transient response, and robustness against uncertainties.

  16. How to Prepare Clay-Lift and Sandwich Slides.

    ERIC Educational Resources Information Center

    Barman, Charles R.

    1984-01-01

    Describes two techniques for making 35 millimeter slides without using photographic film. One method uses clear adhesive contact paper and the other uses transparency film. Both techniques are inexpensive and require only a few minutes of preparation per slide. (JM)

  17. 45. March 26, 1935 View of the big slide of ...

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

    45. March 26, 1935 View of the big slide of several hundred cubic yards of rock, spring of 1934. Another slide occurred at this same location on May 26, 1935. - Scotts Bluff Summit Road, Gering, Scotts Bluff County, NE

  18. Applications of electroporation of adherent cells in situ, on a partly conductive slide.

    PubMed

    Raptis, L H; Brownell, H L; Liu, S K; Firth, K L; MacKenzie, L W; Stiles, C D; Alberta, J A

    1995-10-01

    Nontraumatic, simple, and reproducible procedures for the introduction of nonpermeant molecules into adherent mammalian cells by in situ electroporation are described. Cells are grown on a glass slide, half of which is coated with electrically conductive, optically transparent, indium-tin oxide. An electric pulse is applied in the presence of the molecules to be introduced, and their effect on the cellular phenotype can be observed. The cells growing on the nonconductive side of the slide do not receive any pulse and serve as controls. Careful adjustment of electric field strength can achieve the introduction of the molecules into essentially 100% of the cells, and this treatment causes no detectable disruption to cellular metabolism. This is applied in the presence of the fluorescent dye, Lucifer yellow, causing its penetration into the cells growing on the conductive half of the slide. The migration of the dye to the nonelectroporated cells growing on the nonconductive area is microscopically observed under fluorescence illumination. PMID:8556428

  19. Enhancing Creative Thinking through Designing Electronic Slides

    ERIC Educational Resources Information Center

    Mokaram, Al-Ali Khaled; Al-Shabatat, Ahmad Mohammad; Fong, Fook Soon; Abdallah, Andaleeb Ahmad

    2011-01-01

    During the shifting of teaching and learning methods using computer technologies, much emphasis was paid on the knowledge content more than the thinking skills. Thus, this study investigated the effects of a computer application, namely, designing electronic slides on the development of creative thinking skills of a sample of undergraduate…

  20. Metatarsal-slide lengthening without bone grafting.

    PubMed

    Tabak, B; Lefkowitz, H; Steiner, I

    1986-01-01

    Brachymetatarsia is a condition of premature closure of the epiphyseal plate of a metatarsal. The authors present a case of brachymetatarsia of the second metatarsal. Utilizing a review of the literature, various surgical procedures are discussed. Treatment in this case consisted of a metatarsal-slide lengthening osteotomy, a modification of the Giannestras step-down procedure. PMID:3950333

  1. Simulation of sliding of liquid droplets

    NASA Astrophysics Data System (ADS)

    Alen, Saif Khan; Farhat, Nazia; Rahman, Md. Ashiqur

    2016-07-01

    Numerical simulations of sliding behavior of liquid droplets on flat and periodic microgrooved surfaces with a range of groove geometry are conducted. A numerical model is developed which is capable of predicting the critical sliding angle of the drop by comparing the advancing and the receding angles obtained from numerical and experimental findings. The effect of microgroove topography, droplet size and inclination angle on the droplet sliding characteristics is analysed. Using an open-source platform (Surface Evolver), a 3D drop-shape model is developed to numerically determine the drop stability and contact angle hysteresis on tilted surfaces. In this numerical model, the three phase contact line of the drop is obtained by numerically calculating the vertex force and local contact angle at each vertex of the base contour. Several numerical models are developed based on various assumptions of base contour shape (circular or elliptical) and implementation of gravitational force to the droplet. Droplet shapes and critical sliding angles, obtained from these numerical models, are compared with those of experimental results and are found to be in very good agreement.

  2. Particle Sliding on a Rough Incline

    ERIC Educational Resources Information Center

    Zurcher, Ulrich

    2007-01-01

    We study a particle sliding on a rough inclined plane as an example of a mechanical problem with nonholonomic constraint. The particle is launched in an arbitrary direction so that its motion has both a horizontal and a "vertical" (i.e., up- and downhill) direction. The friction force acts along the instantaneous velocity, so that the horizontal…

  3. Color Microfiche as a Replacement for Slides.

    ERIC Educational Resources Information Center

    Schwarz, Philip

    This is the summary of a larger paper describing the evolution of a mediated elementary accounting course at the University of Wisconsin-Stout. The course was initially developed as a 25 slide-tape lesson course which included 950 visuals and approximately 25 hours of instruction. One hundred students per semester took the course in the following…

  4. Sliding/rolling phobic droplets along a fiber: measurement of interfacial forces.

    PubMed

    Mead-Hunter, Ryan; Bergen, Tanja; Becker, Thomas; O'Leary, Rebecca A; Kasper, Gerhard; Mullins, Benjamin J

    2012-02-21

    Phobic droplet-fiber systems possess complex geometries, which have made full characterization of such systems difficult. This work has used atomic force microscopy (AFM) to measure droplet-fiber forces for oil droplets on oleophobic fibers over a range of fiber diameters. The work adapted a previous method and a theoretical model developed by the authors for philic droplet-fiber systems. A Bayesian statistical model was also used to account for the influence of surface roughness on the droplet-fiber force. In general, it has been found that the force required to move a liquid droplet along an oleophobic filter fiber will be less than that required to move a droplet along an oleophilic fiber. However, because of the effects of pinning and/or wetting behavior, this difference may be less than would otherwise be expected. Droplets with a greater contact angle (~110°) were observed to roll along the fiber, whereas droplets with a lesser contact angle (<90°) would slide. PMID:22260243

  5. Structure of the rat subcutaneous connective tissue in relation to its sliding mechanism.

    PubMed

    Kawamata, Seiichi; Ozawa, Junya; Hashimoto, Masakazu; Kurose, Tomoyuki; Shinohara, Harumichi

    2003-08-01

    Mammalian skin can extensively slide over most parts of the body. To study the mechanism of this mobility of the skin, the structure of the subcutaneous connective tissue was examined by light microscopy. The subcutaneous connective tissue was observed to be composed of multiple layers of thin collagen sheets containing elastic fibers. These piled-up collagen sheets were loosely interconnected with each other, while the outer and inner sheets were respectively anchored to the dermis and epimysium by elastic fibers. Collagen fibers in each sheet were variable in diameter and oriented in different directions to form a thin, loose meshwork under conditions without mechanical stretching. When a weak shear force was loaded between the skin and the underlying abdominal muscles, each collagen sheet slid considerably, resulting in a stretching of the elastic fibers which anchor these sheets. When a further shear force was loaded, collagen fibers in each sheet seemed to align in a more parallel manner to the direction of the tension. With the reduction or removal of the force, the arrangement of collagen fibers in each sheet was reversed and the collagen sheets returned to their original shapes and positions, probably with the stabilizing effect of elastic fibers. Blood vessels and nerves in the subcutaneous connective tissue ran in tortuous routes in planes parallel to the unloaded skin, which seemed very adaptable for the movement of collagen sheets. These findings indicate that the subcutaneous connective tissue is extensively mobile due to the presence of multilayered collagen sheets which are maintained by elastic fibers.

  6. Sliding/rolling phobic droplets along a fiber: measurement of interfacial forces.

    PubMed

    Mead-Hunter, Ryan; Bergen, Tanja; Becker, Thomas; O'Leary, Rebecca A; Kasper, Gerhard; Mullins, Benjamin J

    2012-02-21

    Phobic droplet-fiber systems possess complex geometries, which have made full characterization of such systems difficult. This work has used atomic force microscopy (AFM) to measure droplet-fiber forces for oil droplets on oleophobic fibers over a range of fiber diameters. The work adapted a previous method and a theoretical model developed by the authors for philic droplet-fiber systems. A Bayesian statistical model was also used to account for the influence of surface roughness on the droplet-fiber force. In general, it has been found that the force required to move a liquid droplet along an oleophobic filter fiber will be less than that required to move a droplet along an oleophilic fiber. However, because of the effects of pinning and/or wetting behavior, this difference may be less than would otherwise be expected. Droplets with a greater contact angle (~110°) were observed to roll along the fiber, whereas droplets with a lesser contact angle (<90°) would slide.

  7. Search for associations containing young stars (SACY). VI. Is multiplicity universal? Stellar multiplicity in the range 3-1000 au from adaptive-optics observations

    NASA Astrophysics Data System (ADS)

    Elliott, P.; Huélamo, N.; Bouy, H.; Bayo, A.; Melo, C. H. F.; Torres, C. A. O.; Sterzik, M. F.; Quast, G. R.; Chauvin, G.; Barrado, D.

    2015-08-01

    Context. Young loose nearby associations are unique samples of close (<150 pc), young (≈5-100 Myr) pre-main-sequence (PMS) stars. A significant number of members of these associations have been identified in the SACY (search for associations containing young stars) collaboration. We can use the proximity and youth of these members to investigate key ingredients in star formation processes, such as multiplicity. Aims: With the final goal of better understanding multiplicity properties at different evolutionary stages of PMS stars, we present the statistics of identified multiple systems from 113 confirmed SACY members. We derive multiplicity frequencies, mass-ratio, and physical separation distributions in a consistent parameter space, and compare our results to other PMS populations and the field. Methods: We have obtained adaptive-optics assisted near-infrared observations with the Nasmyth Adaptive Optics System and Near-Infrared Imager and Spectrograph (NACO), ESO/VLT, and the Infrared Camera for Adaptive optics at Lick observatory (IRCAL), Lick Observatory, for at least one epoch of all 113 SACY members. We have identified multiple systems using co-moving proper-motion analysis for targets with multi-epoch data, and using contamination estimates in terms of mass-ratio and physical separation for targets with single-epoch data. We have explored ranges in projected separation and mass-ratio of a [3-1000 au], and q [0.1-1], respectively. Results: We have identified 31 multiple systems (28 binaries and 3 triples). We derive a multiplicity frequency (MF) of MF3-1000 au=28.4+4.7_{-3.9}% and a triple frequency (TF) of TF3-1000 au =2.8 +2.5-0.8% in the separation range of 3-1000 au. We do not find any evidence for an increase in the MF with primary mass. The estimated mass-ratio of our statistical sample (with power-law index γ = -0.04 ± 0.14) is consistent with a flat distribution (γ = 0). Conclusions: Analysis from previous work using tight binaries indicated

  8. Determination of the Earth's pole tide Love number k2 from observations of polar motion using an adaptive Kalman filter approach

    NASA Astrophysics Data System (ADS)

    Seitz, F.; Kirschner, S.; Neubersch, D.

    2012-09-01

    The geophysical interpretation of observed time series of Earth rotation parameters (ERP) is commonly based on numerical models that describe and balance variations of angular momentum in various subsystems of the Earth. Naturally, models are dependent on geometrical, rheological and physical parameters. Many of these are weakly determined from other models or observations. In our study we present an adaptive Kalman filter approach for the improvement of parameters of the dynamic Earth system model DyMEG which acts as a simulator of ERP. In particular we focus on the improvement of the pole tide Love number k2. In the frame of a sensitivity analysis k2 has been identified as one of the most crucial parameters of DyMEG since it directly influences the modeled Chandler oscillation. At the same time k2 is one of the most uncertain parameters in the model. Our simulations with DyMEG cover a period of 60 years after which a steady state of k2 is reached. The estimate for k2, accounting for the anelastic response of the Earth's mantle and the ocean, is 0.3531 + 0.0030i. We demonstrate that the application of the improved parameter k2 in DyMEG leads to significantly better results for polar motion than the original value taken from the Conventions of the International Earth Rotation and Reference Systems Service (IERS).

  9. ADAPTIVE OPTICS OBSERVATIONS OF 3 {mu}m WATER ICE IN SILHOUETTE DISKS IN THE ORION NEBULA CLUSTER AND M43

    SciTech Connect

    Terada, Hiroshi; Pyo, Tae-Soo; Minowa, Yosuke; Hayano, Yutaka; Oya, Shin; Hattori, Masayuki; Takami, Hideki; Tokunaga, Alan T.; Watanabe, Makoto; Saito, Yoshihiko; Ito, Meguru; Iye, Masanori

    2012-12-01

    We present the near-infrared images and spectra of four silhouette disks in the Orion Nebula Cluster (M42) and M43 using the Subaru Adaptive Optics system. While d053-717 and d141-1952 show no water ice feature at 3.1 {mu}m, a moderately deep ({tau}{sub ice} {approx} 0.7) water ice absorption is detected toward d132-1832 and d216-0939. Taking into account the water ice so far detected in the silhouette disks, the critical inclination angle to produce a water ice absorption feature is confirmed to be 65 Degree-Sign -75 Degree-Sign . As for d216-0939, the crystallized water ice profile is exactly the same as in the previous observations taken 3.63 years ago. If the water ice material is located at 30 AU, then the observations suggest it is uniform at a scale of about 3.5 AU.

  10. Mechanism of sand slide - cold lahar induced by extreme rainfall

    NASA Astrophysics Data System (ADS)

    Fukuoka, Hiroshi; Yamada, Masumi; Dok, Atitkagna

    2014-05-01

    Along with the increasing frequencies of extreme rainfall events in almost every where on the earth, shallow slide - debris flow, i.e. cold lahars running long distance often occurs and claims downslope residents lives. In the midnight of 15 October 2013, Typhoon Wilpha attacked the Izu-Oshima, a active volcanic Island and the extreme rainfall of more than 800 mm / 24 hours was recorded. This downpour of more than 80 mm/hr lasted 4 hours at its peak and caused a number of cold lahars. The initial stage of those lahars was shallow slides of surface black volcanic ash deposits, containing mostly fine sands. The thickness was only 50 cm - 1 m. In the reconnaissance investigation, author found that the sliding surface was the boundary of two separate volcanic ash layers between the black and yellow colored and apparently showing contrast of permeability and hardness. Permeability contrast may have contributed to generation of excess pore pressure on the border and trigger the slide. Then, the unconsolidated, unpacked mass was easily fluidized and transformed into mud flows, that which volcanologists call cold lahars. Seismometers installed for monitoring the active volcano's activities, succeeded to detect many tremors events. Many are spikes but 5 larger and longer events were extracted. They lasted 2 -3 minutes and if we assume that this tremors reflects the runout movement, then we can calculate the mean velocity of the lahars. Estimated velocity was 45 - 60 km/h, which is much higher than the average speed 30 - 40 km/h of debris flows observed in Japan. Flume tests of volcanic ash flows by the Forestry and Forest Products Research Institute showed the wet volcanic ash can run at higher speed than other materials. The two tremor records were compare d with the local residents witnessed and confirmed by newspaper reported that the reach of the lahar was observed at the exact time when tremor ends. We took the black volcanic ash and conducted ring shear tests to

  11. Probing Hypergiant Mass Loss with Adaptive Optics Imaging and Polarimetry in the Infrared: MMT-Pol and LMIRCam Observations of IRC +10420 and VY Canis Majoris

    NASA Astrophysics Data System (ADS)

    Shenoy, Dinesh P.; Jones, Terry J.; Packham, Chris; Lopez-Rodriguez, Enrique

    2015-07-01

    We present 2-5 μm adaptive optics (AO) imaging and polarimetry of the famous hypergiant stars IRC +10420 and VY Canis Majoris. The imaging polarimetry of IRC +10420 with MMT-Pol at 2.2 μ {m} resolves nebular emission with intrinsic polarization of 30%, with a high surface brightness indicating optically thick scattering. The relatively uniform distribution of this polarized emission both radially and azimuthally around the star confirms previous studies that place the scattering dust largely in the plane of the sky. Using constraints on scattered light consistent with the polarimetry at 2.2 μ {m}, extrapolation to wavelengths in the 3-5 μm band predicts a scattered light component significantly below the nebular flux that is observed in our Large Binocular Telescope/LMIRCam 3-5 μm AO imaging. Under the assumption this excess emission is thermal, we find a color temperature of ˜500 K is required, well in excess of the emissivity-modified equilibrium temperature for typical astrophysical dust. The nebular features of VY CMa are found to be highly polarized (up to 60%) at 1.3 μm, again with optically thick scattering required to reproduce the observed surface brightness. This star’s peculiar nebular feature dubbed the “Southwest Clump” is clearly detected in the 3.1 μm polarimetry as well, which, unlike IRC +10420, is consistent with scattered light alone. The high intrinsic polarizations of both hypergiants’ nebulae are compatible with optically thick scattering for typical dust around evolved dusty stars, where the depolarizing effect of multiple scatters is mitigated by the grains’ low albedos. Observations reported here were obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona.

  12. Probing Hypergiant Mass Loss with Adaptive Optics Imaging and Polarimetry in the Infrared: MMT-Pol and LMIRCam Observations of IRC +10420 and VY Canis Majoris

    NASA Astrophysics Data System (ADS)

    Shenoy, Dinesh P.; Jones, Terry J.; Packham, Chris; Lopez-Rodriguez, Enrique

    2015-07-01

    We present 2–5 μm adaptive optics (AO) imaging and polarimetry of the famous hypergiant stars IRC +10420 and VY Canis Majoris. The imaging polarimetry of IRC +10420 with MMT-Pol at 2.2 μ {m} resolves nebular emission with intrinsic polarization of 30%, with a high surface brightness indicating optically thick scattering. The relatively uniform distribution of this polarized emission both radially and azimuthally around the star confirms previous studies that place the scattering dust largely in the plane of the sky. Using constraints on scattered light consistent with the polarimetry at 2.2 μ {m}, extrapolation to wavelengths in the 3–5 μm band predicts a scattered light component significantly below the nebular flux that is observed in our Large Binocular Telescope/LMIRCam 3–5 μm AO imaging. Under the assumption this excess emission is thermal, we find a color temperature of ∼500 K is required, well in excess of the emissivity-modified equilibrium temperature for typical astrophysical dust. The nebular features of VY CMa are found to be highly polarized (up to 60%) at 1.3 μm, again with optically thick scattering required to reproduce the observed surface brightness. This star’s peculiar nebular feature dubbed the “Southwest Clump” is clearly detected in the 3.1 μm polarimetry as well, which, unlike IRC +10420, is consistent with scattered light alone. The high intrinsic polarizations of both hypergiants’ nebulae are compatible with optically thick scattering for typical dust around evolved dusty stars, where the depolarizing effect of multiple scatters is mitigated by the grains’ low albedos. Observations reported here were obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona.

  13. A survey of Io's vocanism by adaptive optics observations in the 3.8-μm thermal band (1996-1999)

    NASA Astrophysics Data System (ADS)

    Marchis, Franck; Prangé, Renée; Fusco, Thierry

    2001-12-01

    In this study, we analyze a series of images of Io obtained with the European Southern Observatory adaptive optics system (Adaptive Optics Near Infrared System, ADONIS) at 3.8 μm from 1996 to 1999, with particular emphasis on the observations carried out in late 1999 in support of the Galileo flybys of Io. Use of a new myopic deconvolution method, Myopic Iterative Step Preserving Algorithm (MISTRAL), especially designed for planetary objects, significantly improves the quality and the reliability of the reconstructed images. Using a simulation of artificial images of Io, we estimate the extent to which this algorithm is able to prevent noise amplification, to better restore sharp edges, and to preserve the initial photometry. Once this algorithm has been applied to our data and the solar-reflected background has been subtracted, we have 89 images of Io available for search and temporal survey of the hot spots over 4 years. In most cases, the data, acquired during two consecutive nights, provide an almost global view of the surface of Io. We identify 20 hot spots for which we determine the coordinates and the brightness at 3.8 μm (as a function of time). More than half of the hot spots were detected on all the images and were considered as persistent. Particular emphasis has been put on the brightest two hot spots, Loki and Pele, for which we obtain a center-to-limb variation curve (a cosine curve for Loki and a curve decreasing slightly faster than a cosine law for Pele with possible physical interpretations). The temporal variations of their activity have been derived over these 4 years and, for Loki, compared with the results of other ground-based surveys. The variability of the other, fainter, sources has also been derived but with less accuracy. We have also identified a few new hot spots, some of which are transient, such as a diffuse emission seen in September and November 1999 at the location of the upcoming Tvashtar outburst. The data are based on

  14. Fluid pressure responses for a Devil's Slide-like system: problem formulation and simulation

    USGS Publications Warehouse

    Thomas, Matthew A.; Loague, Keith; Voss, Clifford I.

    2015-01-01

    This study employs a hydrogeologic simulation approach to investigate subsurface fluid pressures for a landslide-prone section of the central California, USA, coast known as Devil's Slide. Understanding the relative changes in subsurface fluid pressures is important for systems, such as Devil's Slide, where slope creep can be interrupted by episodic slip events. Surface mapping, exploratory core, tunnel excavation records, and dip meter data were leveraged to conceptualize the parameter space for three-dimensional (3D) Devil's Slide-like simulations. Field observations (i.e. seepage meter, water retention, and infiltration experiments; well records; and piezometric data) and groundwater flow simulation (i.e. one-dimensional vertical, transient, and variably saturated) were used to design the boundary conditions for 3D Devil's Slide-like problems. Twenty-four simulations of steady-state saturated subsurface flow were conducted in a concept-development mode. Recharge, heterogeneity, and anisotropy are shown to increase fluid pressures for failure-prone locations by up to 18.1, 4.5, and 1.8% respectively. Previous estimates of slope stability, driven by simple water balances, are significantly improved upon with the fluid pressures reported here. The results, for a Devil's Slide-like system, provide a foundation for future investigations

  15. Sliding and Abrasive Wear Behavior of WC-CoCr Coatings with Different Carbide Sizes

    NASA Astrophysics Data System (ADS)

    Thakur, Lalit; Arora, Navneet

    2013-02-01

    This study examines the sliding and abrasive wear behaviors of high-velocity oxy-fuel (HVOF)-sprayed WC-CoCr coatings with different WC grain sizes. The HVOF coating deposition was assisted by in-flight particle temperature and velocity measurement system. The powder feedstocks and their corresponding coatings were characterized by means of XRD and Field Emission Scanning Electron Microscope analysis. Hardness, porosity, and indentation fracture toughness of these coatings were calculated and compared with each other. Sliding wear resistance of these coatings was calculated using pin-on-disk tribometer (ASTM G99-90). The two-body abrasion was quantified by sliding the samples over silicon carbide (SiC) abrasive paper bonded to a rotating flat disk of auto-polisher. The mechanism of materials' removal in both the sliding and abrasive wears was studied and discussed on microstructural investigations. It was observed that fine grain WC-CoCr cermet coating exhibits higher sliding and abrasive wear resistances as compared with conventional cermet coating.

  16. The Influence of Interfacial Roughness on Fiber Sliding in Oxide Composites with La-Monazite Interphases

    NASA Technical Reports Server (NTRS)

    Davis, J. B.; Hay, R. S.; Marshall, D. B.; Morgan, P. E. D.; Sayir, A.; Gray, Hugh R. (Technical Monitor); Farmer, Serene C. (Technical Monitor)

    2002-01-01

    Room temperature debonding and sliding of La-Monazite coated fibers is assessed using a composite with a polycrystalline alumina matrix and fibers of several different single crystal (mullite, sapphire) and directionally solidified eutectic (Al2O3/Y3Al5O12 and Al2O3/Y-ZrO2) compositions. These fibers provide a range of residual stresses and interfacial roughnesses. Sliding occurred over a debond crack at the fiber-coating interface when the sliding displacement and surface roughness were relatively small. At large sliding displacements with relatively rough interfaces, the monazite coatings were deformed extensively by fracture, dislocations and occasional twinning, whereas the fibers were undamaged. Dense, fine-grained (10 nm) microstructures suggestive of dynamic recrystallization were also observed in the coatings. Frictional heating during sliding is assessed. The possibility of low temperature recrystallization is discussed in the light of the known resistance of monazite to radiation damage. The ability of La-Monazite to undergo plastic deformation relatively easily at low temperatures may be enabling for its use as a composite interface.

  17. Onset of frictional sliding of rubber–glass contact under dry and lubricated conditions

    PubMed Central

    Tuononen, Ari J.

    2016-01-01

    Rubber friction is critical in many applications ranging from automotive tyres to cylinder seals. The process where a static rubber sample transitions to frictional sliding is particularly poorly understood. The experimental and simulation results in this paper show a completely different detachment process from the static situation to sliding motion under dry and lubricated conditions. The results underline the contribution of the rubber bulk properties to the static friction force. In fact, simple Amontons’ law is sufficient as a local friction law to produce the correct detachment pattern when the rubber material and loading conditions are modelled properly. Simulations show that micro-sliding due to vertical loading can release initial shear stresses and lead to a high static/dynamic friction coefficient ratio, as observed in the measurements. PMID:27291939

  18. Onset of frictional sliding of rubber–glass contact under dry and lubricated conditions

    NASA Astrophysics Data System (ADS)

    Tuononen, Ari J.

    2016-06-01

    Rubber friction is critical in many applications ranging from automotive tyres to cylinder seals. The process where a static rubber sample transitions to frictional sliding is particularly poorly understood. The experimental and simulation results in this paper show a completely different detachment process from the static situation to sliding motion under dry and lubricated conditions. The results underline the contribution of the rubber bulk properties to the static friction force. In fact, simple Amontons’ law is sufficient as a local friction law to produce the correct detachment pattern when the rubber material and loading conditions are modelled properly. Simulations show that micro-sliding due to vertical loading can release initial shear stresses and lead to a high static/dynamic friction coefficient ratio, as observed in the measurements.

  19. Onset of frictional sliding of rubber-glass contact under dry and lubricated conditions.

    PubMed

    Tuononen, Ari J

    2016-01-01

    Rubber friction is critical in many applications ranging from automotive tyres to cylinder seals. The process where a static rubber sample transitions to frictional sliding is particularly poorly understood. The experimental and simulation results in this paper show a completely different detachment process from the static situation to sliding motion under dry and lubricated conditions. The results underline the contribution of the rubber bulk properties to the static friction force. In fact, simple Amontons' law is sufficient as a local friction law to produce the correct detachment pattern when the rubber material and loading conditions are modelled properly. Simulations show that micro-sliding due to vertical loading can release initial shear stresses and lead to a high static/dynamic friction coefficient ratio, as observed in the measurements. PMID:27291939

  20. Mechanism of gene-regulating protein's diffusion along DNA: hopping vs. sliding

    NASA Astrophysics Data System (ADS)

    Wang, Yan Mei; Cox, Edward; Austin, Robert

    2006-03-01

    It has been a long controversy as whether non-energy-driven proteins diffuse along DNA in the form of hopping or sliding. In the hopping model, the protein jumps on and off DNA frequently while diffusing, switching between 1D and 3D diffusions, and in the sliding model the protein diffuses along DNA basepair by basepair, staying in continuous contact with the DNA. We have investigated the diffusion mechanisms of LacI repressor protein along nonspecific sequences of DNA using single molecule imaging measurements. By studying the standard deviation (SD) of the diffusing LacI’s point spread functions, we observed that the SD values in both the longitudinal and transverse directions to DNA elongation to be significantly higher than what can be accounted for by the sliding model. We will show that the large SD values agree with the hopping model.

  1. Onset of frictional sliding of rubber-glass contact under dry and lubricated conditions

    NASA Astrophysics Data System (ADS)

    Tuononen, Ari J.

    2016-06-01

    Rubber friction is critical in many applications ranging from automotive tyres to cylinder seals. The process where a static rubber sample transitions to frictional sliding is particularly poorly understood. The experimental and simulation results in this paper show a completely different detachment process from the static situation to sliding motion under dry and lubricated conditions. The results underline the contribution of the rubber bulk properties to the static friction force. In fact, simple Amontons’ law is sufficient as a local friction law to produce the correct detachment pattern when the rubber material and loading conditions are modelled properly. Simulations show that micro-sliding due to vertical loading can release initial shear stresses and lead to a high static/dynamic friction coefficient ratio, as observed in the measurements.

  2. Operational seismic network estimates rock slide properties

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2012-02-01

    During the spring of 1991, two subsequent landslides near Randa, Switzerland, dropped 30,000,000 cubic meters of debris on the town below. The rocks dammed the Vispa River, a temporary reservoir that would have failed catastrophically had the army not carved a channel through it. Many rock slides occur in remote alpine locations, so it can sometimes take days or weeks before they are detected, a delay that could have cost the town of Randa. Rock slides can range from deadly, to disruptive, to simple scientific curiosities.Dammeier et al. have developed a method to remotely estimate their volume, location, and runout distances that could potentially be used in real time.

  3. Vesicocutaneous fistula after sliding hernia repair

    PubMed Central

    Mittal, Varun; Kapoor, Rakesh; Sureka, Sanjoy

    2016-01-01

    Sliding inguinal hernias are usually direct inguinal hernias containing various abdominal viscera. The incidence of bladder forming a part of an inguinal hernia, called as “scrotal cystocele,” is 1–4%. The risk of bladder injury is as high as 12% when repairing this type of hernia. This case report emphasizes this aspect in a 65-year-old man who presented with urinary leak through the scrotal wound following right inguinal hernia repair. PMID:26941501

  4. Fast Convolution Using Generalized Sliding Fermat Number Transform with Application to Digital Filtering

    NASA Astrophysics Data System (ADS)

    Alaeddine, Hamzé Haidar; Bazzi, Oussama; Alaeddine, Ali Haidar; Mohanna, Yasser; Burel, Gilles

    This paper is about a new efficient method for the implementation of a Block Proportionate Normalized Least Mean Square (BPNLMS++) adaptive filter using the Fermat Number Transform (FNT) and its inverse (IFNT). These transforms present advantages compared to Fast Fourier Transform (FFT) and the inverse (IFFT). An efficient state space method for implementing the FNT over rectangular windows is used in the cases where there is a large overlap between the consecutive input signals. This is called Generalized Sliding Fermat Number Transform (GSFNT) and is useful for reducing the computational complexity of finite ring convolvers and correlators. In this contribution, we propose, as a first objective, an efficient state algorithm with the purpose of reducing the complexity of IFNT. This algorithm, called Inverse Generalized Sliding Fermat Number Transform (IGSFNT), uses the technique of Generalized Sliding associated to matricial calculation in the Galois Field. The second objective is to realize an implementation of the BPNLMS++ adaptive filter using GSFNT and IGSFNT, which can significantly reduce the computation complexity of the filter implantation on digital signal processors.

  5. A comparative study of input devices for digital slide navigation

    PubMed Central

    Molin, Jesper; Lundström, Claes; Fjeld, Morten

    2015-01-01

    This paper describes work presented at the Nordic Symposium on Digital Pathology 2014, Linköping, Sweden. Quick and seamless integration between input devices and the navigation of digital slides remains a key barrier for many pathologists to “go digital.” To better understand this integration, three different input device implementations were compared in terms of time to diagnose, perceived workload and users’ preferences. Six pathologists reviewed in total nine cases with a computer mouse, a 6 degrees-of-freedom (6DOF) navigator and a touchpad. The participants perceived significantly less workload (P < 0.05) with the computer mouse and the 6DOF navigator, than with the touchpad, while no effect of the input device used on the time to diagnose was observed. Five out of six pathologists preferred the 6DOF navigator, while the touchpad was the least preferred device. While digital slide navigation is often designed to mimic microscope interaction, the results of this study demonstrate that in order to minimize workload there is reason to let the digital interaction move beyond the familiar microscope tradition. PMID:25774318

  6. A comparative study of input devices for digital slide navigation.

    PubMed

    Molin, Jesper; Lundström, Claes; Fjeld, Morten

    2015-01-01

    This paper describes work presented at the Nordic Symposium on Digital Pathology 2014, Linköping, Sweden. Quick and seamless integration between input devices and the navigation of digital slides remains a key barrier for many pathologists to "go digital." To better understand this integration, three different input device implementations were compared in terms of time to diagnose, perceived workload and users' preferences. Six pathologists reviewed in total nine cases with a computer mouse, a 6 degrees-of-freedom (6DOF) navigator and a touchpad. The participants perceived significantly less workload (P < 0.05) with the computer mouse and the 6DOF navigator, than with the touchpad, while no effect of the input device used on the time to diagnose was observed. Five out of six pathologists preferred the 6DOF navigator, while the touchpad was the least preferred device. While digital slide navigation is often designed to mimic microscope interaction, the results of this study demonstrate that in order to minimize workload there is reason to let the digital interaction move beyond the familiar microscope tradition.

  7. Slide-specific models for segmentation of differently stained digital histopathology whole slide images

    NASA Astrophysics Data System (ADS)

    Brieu, Nicolas; Pauly, Olivier; Zimmermann, Johannes; Binnig, Gerd; Schmidt, Günter

    2016-03-01

    The automatic analysis of whole slide images (WSIs) of stained histopathology tissue sections plays a crucial role in the discovery of predictive biomarkers in the field on immuno-oncology by enabling the quantification of the phenotypic information contained in the tissue sections. The automatic detection of cells and nuclei, while being one of the major steps of such analysis, remains a difficult problem because of the low visual differentiation of high pleomorphic and densely cluttered objects and of the diversity of tissue appearance between slides. The key idea of this work is to take advantage of well-differentiated objects in each slide to learn about the appearance of the tissue and in particular about the appearance of low-differentiated objects. We detect well-differentiated objects on a automatically selected set of representative regions, learn slide-specific visual context models, and finally use the resulting posterior maps to perform the final detection steps on the whole slide. The accuracy of the method is demonstrated against manual annotations on a set of differently stained images.

  8. Influence of carbon nanotube addition on sliding wear behaviour of pulse electrodeposited cobalt (Co)-phosphorus (P) coatings

    NASA Astrophysics Data System (ADS)

    Edward Anand, E.; Natarajan, S.

    2015-09-01

    This work examines the sliding wear behaviour of nanostructured cobalt-phosphorus (Co-P) alloy electrodeposits reinforced with multiwalled carbon nanotubes (MWCNTs). Nanocrystalline cobalt-phosphorus alloy coatings reinforced with carbon nanotubes were produced by pulse electrodeposition from an aqueous bath. Tribological properties of the coatings with and without MWCNT addition were characterized. Anisotropic tribological behaviour was observed for the coatings reinforced with MWCNTs when slided against hard steel counterparts. The nanocrystalline Co-P-CNT coatings display better wear resistance and friction reduction compared with the nanocrystalline Co-P coating. The friction coefficients and wear rates of the nanocrystalline Co-P-CNT coating are influenced by the test conditions including the applied load, sliding speed and more importantly the alignment of MWCNTs in the deposits. The wear mechanisms of the nanocrystalline Co-P and Co-P-CNT alloy coatings involved in different sliding conditions are explained related to their friction and wear properties.

  9. Neuro-sliding mode control with its applications to seesaw systems.

    PubMed

    Tsai, Chun-Hsien; Chung, Hung-Yuan; Yu, Fang-Ming

    2004-01-01

    This paper proposes an approach of cooperative control that is based on the concept of combining neural networks and the methodology of sliding mode control (SMC). The main purpose is to eliminate the chattering phenomenon. Next, the system performance can be improved by using the method of SMC. In the present approach, two parallel Neural Networks are utilized to realize a neuro-sliding mode control (NSMC), where the equivalent control and the corrective control are the outputs of neural network 1 and neural network 2, respectively. Based on expressions of the SMC, the weight adaptations of neural network can be determined. Furthermore, the gradient descent method is used to minimize the control force so that the chattering phenomenon can be eliminated. Finally, experimental results are given to show the effectiveness and feasibility of the approach.

  10. "The living picture": on the circulation of microscope-slide knowledge in 1903.

    PubMed

    Gaycken, Oliver

    2013-01-01

    Microscope slides allowed preparations to circulate among scientific and educational contexts. An extension of the circulation of microscope slides was how they became part of lantern exhibition culture. This article considers an early example of the adoption of microscope lantern show conventions by another medium, the cinema. E Martin Duncan, who was employed by Charles Urban to produce a series of popular-science films beginning in 1903, brought his experience with microphotography to bear on the challenge of adapting cinema to the purpose of public instruction. Duncan's first series of films, entitled "The Unseen World," demonstrated both profound links to the display tradition of the lantern lecture as well as the transformation of that tradition by the cinema's representational possibilities. PMID:24779105

  11. A simple method to evaluate the reliability of OWAS observations.

    PubMed

    de Bruijn, I; Engels, J A; van der Gulden, J W

    1998-08-01

    Slides showing nurses in different working postures were used to determine the reliability of OWAS observations. Each slide could be looked at for 3 seconds, while a new slide was shown every 30 seconds to resemble the normal practice of observation. Two observers twice scored a series of slides, some of them being identical at both viewings. To reduce effects of recall there was a time interval of 4 weeks or more between the two viewings and the slides were in a different order the second time. Different series were used to evaluate inter- and intra-observer reliability. The OWAS scores of corresponding slides were compared. In almost all comparisons percentages of agreement over 85% and kappa's over 0.6 were found, which is considered as good agreement. The procedure described seems to be a useful and simple technique to determine such reliability.

  12. Two dimensional nanoscale reciprocating sliding contacts of textured surfaces

    NASA Astrophysics Data System (ADS)

    Tong, Ruiting; Liu, Geng; Liu, Tianxiang

    2016-05-01

    Detailed behaviors of nanoscale textured surfaces during the reciprocating sliding contacts are still unknown although they are widely used in mechanical components to improve tribological characteristics. The current research of sliding contacts of textured surfaces mainly focuses on the experimental studies, while the cost is too high. Molecular dynamics(MD) simulation is widely used in the studies of nanoscale single-pass sliding contacts, but the CPU cost of MD simulation is also too high to simulate the reciprocating sliding contacts. In this paper, employing multiscale method which couples molecular dynamics simulation and finite element method, two dimensional nanoscale reciprocating sliding contacts of textured surfaces are investigated. Four textured surfaces with different texture shapes are designed, and a rigid cylindrical tip is used to slide on these textured surfaces. For different textured surfaces, average potential energies and average friction forces of the corresponding sliding processes are analyzed. The analyzing results show that "running-in" stages are different for each texture, and steady friction processes are discovered for textured surfaces II, III and IV. Texture shape and sliding direction play important roles in reciprocating sliding contacts, which influence average friction forces greatly. This research can help to design textured surfaces to improve tribological behaviors in nanoscale reciprocating sliding contacts.

  13. The binarity of Herbig Ae/Be stars observed with Adaptive Optics and spectroscopy. A study of the triple system TY CrA

    NASA Astrophysics Data System (ADS)

    Corporon, Patrice

    1998-03-01

    Multiplicity is a major issue in stellar astrophysics. Firstly, any stellar formation theory must explain the large abundance of multiple systems among Main Sequence and young low-mass T Tauri stars. Secondly, binary studies allow the direct determination of physical parameters. In the case of Herbig Ae/Be (HAeBe) stars, the binarity status is not well known; furthermore, direct mass determination are required to test stellar evolution models for these young intermediate mass objects. The first part of the thesis presents the results of a systematic search for HAeBe binaries in both hemispheres. Two complementary techniques were used to cover a large range of orbital period P: high angular resolution imaging with Adaptive Optics (AO) (binary separation ρ between 0.12'' and few arcseconds, i.e. P ≅ many years), and high resolution visible spectroscopy to study short orbital period (P ≅few hours to few months). Among the 68 HAeBe stars observed with ADONIS--ESO and PUEO--CFH AO instruments, 30 binaries (18 discovered) have been detected. 42 HAeBe stars have been surveyed with the CES--ESO and 'ELODIE, AURéLIE--OHP spectrographs. Radial velocity variations were found in 7 targets (4 are new spectroscopic binaries, 3 d. < P < 166 d.). In addition, the 7Li 6 708 Å absorption line (absent feature in simple HAeBe stars spectra) indicates the presence of a cooler companion in 6 HAeBe spectrum binaries, 4 of which are new detections. The observed visual binary frequency for HAeBe stars is of the order of 50%. For short period spectroscopic binaries (P < 100 days), the observed frequency is about 10%. Considering observational bias effects, these estimates are regarded as lower limits for the true HAeBe binary frequency. Based on our multi-color AO images, spectral types of twenty-two visual companions have been determined. A trend is found such that companions of Ae stars are low-mass T Tauri stars (spectral type K--M), while companions of Be stars are intermediate

  14. Adapting the McMaster-Ottawa scale and developing behavioral anchors for assessing performance in an interprofessional Team Observed Structured Clinical Encounter

    PubMed Central

    Lie, Désirée; May, Win; Richter-Lagha, Regina; Forest, Christopher; Banzali, Yvonne; Lohenry, Kevin

    2015-01-01

    Background Current scales for interprofessional team performance do not provide adequate behavioral anchors for performance evaluation. The Team Observed Structured Clinical Encounter (TOSCE) provides an opportunity to adapt and develop an existing scale for this purpose. We aimed to test the feasibility of using a retooled scale to rate performance in a standardized patient encounter and to assess faculty ability to accurately rate both individual students and teams. Methods The 9-point McMaster-Ottawa Scale developed for a TOSCE was converted to a 3-point scale with behavioral anchors. Students from four professions were trained a priori to perform in teams of four at three different levels as individuals and teams. Blinded faculty raters were trained to use the scale to evaluate individual and team performances. G-theory was used to analyze ability of faculty to accurately rate individual students and teams using the retooled scale. Results Sixteen faculty, in groups of four, rated four student teams, each participating in the same TOSCE station. Faculty expressed comfort rating up to four students in a team within a 35-min timeframe. Accuracy of faculty raters varied (38–81% individuals, 50–100% teams), with errors in the direction of over-rating individual, but not team performance. There was no consistent pattern of error for raters. Conclusion The TOSCE can be administered as an evaluation method for interprofessional teams. However, faculty demonstrate a ‘leniency error’ in rating students, even with prior training using behavioral anchors. To improve consistency, we recommend two trained faculty raters per station. PMID:26004993

  15. Needs assessment for adapting TB directly observed treatment intervention programme in Limpopo Province, South Africa: A community-based participatory research approach

    PubMed Central

    Khoza, Lunic B.; Van den Borne, Hubertus B.; Lebese, Rachel T.

    2016-01-01

    Background Limpopo Province is one of the hardest hit by tuberculosis and human immune virus infections in the country. The province has been implementing a directly observed treatment strategy since 1996. However, the cure rate was 64% in 2015 and remains far from the set target by the World Health Organization of 85%. Poor health-care seeking and adherence behaviours were identified as major risk behaviours. Aim To apply a Community-Based Participatory Research (CBPR) approach in identifying barriers and facilitators to health-care seeking and adherence to treatment, and to determine strategies and messages in order to inform the design of an adapted intervention programme. Setting This study was conducted in three districts in the Limpopo Province, Capricorn, Mopani and Sekhukhune districts. Methods The community participatory research approach was applied. Purposive sampling was used to sample participants. Focus group discussions were used to collect data. Participatory analysis was used comparing findings within and across all the participants. Results A total of 161 participated in the study. Participants included coordinators, professional nurses, supporters and patients. Major modifiable behavioural-related barriers were lack of knowledge about tuberculosis, misinformation and misperceptions cultural beliefs, stigma and refusal of treatment support. Environment-related barriers were attitudes of health workers, lack of support by family and community, lack of food and use of alcohol and drugs. Strategies and messages included persuasive and motivational messages to promote healthy behaviour. Conclusion Joint programmatic collaboration between the community and academic researchers is really needed for interventions to address the needs of the community. PMID:27542290

  16. Adaptive servo-ventilation therapy using an innovative ventilator for patients with chronic heart failure: a real-world, multicenter, retrospective, observational study (SAVIOR-R).

    PubMed

    Momomura, Shin-Ichi; Seino, Yoshihiko; Kihara, Yasuki; Adachi, Hitoshi; Yasumura, Yoshio; Yokoyama, Hiroyuki

    2015-11-01

    Adaptive servo-ventilation (ASV) therapy using an innovative ventilator-originally developed to treat sleep-disordered breathing (SDB)-is a novel modality of noninvasive positive pressure ventilation and is gaining acceptance among Japanese cardiologists in expectation of its applicability to treat patients with chronic heart failure (CHF) based on its acute beneficial hemodynamic effects. We conducted a multicenter, retrospective, real-world observational study in 115 Japanese patients with CHF, who had undergone home ASV therapy for the first time from January through December 2009, to examine their profile and the effects on their symptoms and hemodynamics. Medical records were used to investigate New York Heart Association (NYHA) class, echocardiographic parameters including left ventricular ejection fraction (LVEF), cardiothoracic ratio (CTR), brain natriuretic peptide (BNP), and other variables. Most of the patients were categorized to NYHA classes II (44.4 %) and III (40.7 %). SDB severity was not determined in 44 patients, and SDB was not detected or was mild in 27 patients. In at least 71 patients (61.7 %), therefore, ASV therapy was not applied for the treatment of SDB. CHF was more severe, i.e., greater NYHA class, lower LVEF, and higher CTR, in 87 ASV-continued patients (75.7 %) than in 28 ASV-discontinued patients (24.3 %). However, SDB severity was not related to continuity of ASV. The combined proportion of NYHA classes III and IV (P = 0.012) and LVEF (P = 0.009) improved significantly after ASV therapy. CTR and BNP did not improve significantly after ASV therapy but showed significant beneficial changes in their time-course analysis (P < 0.05, respectively). Improvements in LVEF and NYHA class after ASV therapy were not influenced by SDB severity at onset. The present study suggests that ASV therapy would improve the symptoms and hemodynamics of CHF patients, regardless of SDB severity. A randomized clinical study to verify these effects is

  17. Zooming in: high resolution 3D reconstruction of differently stained histological whole slide images

    NASA Astrophysics Data System (ADS)

    Lotz, Johannes; Berger, Judith; Müller, Benedikt; Breuhahn, Kai; Grabe, Niels; Heldmann, Stefan; Homeyer, André; Lahrmann, Bernd; Laue, Hendrik; Olesch, Janine; Schwier, Michael; Sedlaczek, Oliver; Warth, Arne

    2014-03-01

    Much insight into metabolic interactions, tissue growth, and tissue organization can be gained by analyzing differently stained histological serial sections. One opportunity unavailable to classic histology is three-dimensional (3D) examination and computer aided analysis of tissue samples. In this case, registration is needed to reestablish spatial correspondence between adjacent slides that is lost during the sectioning process. Furthermore, the sectioning introduces various distortions like cuts, folding, tearing, and local deformations to the tissue, which need to be corrected in order to exploit the additional information arising from the analysis of neighboring slide images. In this paper we present a novel image registration based method for reconstructing a 3D tissue block implementing a zooming strategy around a user-defined point of interest. We efficiently align consecutive slides at increasingly fine resolution up to cell level. We use a two-step approach, where after a macroscopic, coarse alignment of the slides as preprocessing, a nonlinear, elastic registration is performed to correct local, non-uniform deformations. Being driven by the optimization of the normalized gradient field (NGF) distance measure, our method is suitable for differently stained and thus multi-modal slides. We applied our method to ultra thin serial sections (2 μm) of a human lung tumor. In total 170 slides, stained alternately with four different stains, have been registered. Thorough visual inspection of virtual cuts through the reconstructed block perpendicular to the cutting plane shows accurate alignment of vessels and other tissue structures. This observation is confirmed by a quantitative analysis. Using nonlinear image registration, our method is able to correct locally varying deformations in tissue structures and exceeds the limitations of globally linear transformations.

  18. Optimal second order sliding mode control for linear uncertain systems.

    PubMed

    Das, Madhulika; Mahanta, Chitralekha

    2014-11-01

    In this paper an optimal second order sliding mode controller (OSOSMC) is proposed to track a linear uncertain system. The optimal controller based on the linear quadratic regulator method is designed for the nominal system. An integral sliding mode controller is combined with the optimal controller to ensure robustness of the linear system which is affected by parametric uncertainties and external disturbances. To achieve finite time convergence of the sliding mode, a nonsingular terminal sliding surface is added with the integral sliding surface giving rise to a second order sliding mode controller. The main advantage of the proposed OSOSMC is that the control input is substantially reduced and it becomes chattering free. Simulation results confirm superiority of the proposed OSOSMC over some existing.

  19. Sliding wear and friction behaviour of zircaloy-4 in water

    NASA Astrophysics Data System (ADS)

    Sharma, Garima; Limaye, P. K.; Jadhav, D. T.

    2009-11-01

    In water cooled nuclear reactors, the sliding of fuel bundles in fuel channel handling system can lead to severe wear and it is an important topic to study. In the present study, sliding wear behaviour of zircaloy-4 was investigated in water (pH ˜ 10.5) using ball-on-plate sliding wear tester. Sliding wear resistance zircaloy-4 against SS 316 was examined at room temperature. Sliding wear tests were carried out at different load and sliding frequencies. The coefficient of friction of zircaloy-4 was also measured during each tests and it was found to decrease slightly with the increase in applied load. The micro-mechanisms responsible for wear in zircaloy-4 were identified to be microcutting, micropitting and microcracking of deformed subsurface zones in water.

  20. Maximum limit to the number of myosin II motors participating in processive sliding of actin.

    PubMed

    Rastogi, Khushboo; Puliyakodan, Mohammed Shabeel; Pandey, Vikas; Nath, Sunil; Elangovan, Ravikrishnan

    2016-01-01

    In this work, we analysed processive sliding and breakage of actin filaments at various heavy meromyosin (HMM) densities and ATP concentrations in IVMA. We observed that with addition of ATP solution, the actin filaments fragmented stochastically; we then determined mean length and velocity of surviving actin filaments post breakage. Average filament length decreased with increase in HMM density at constant ATP, and increased with increase in ATP concentration at constant HMM density. Using density of HMM molecules and length of actin, we estimated the number of HMM molecules per actin filament (N) that participate in processive sliding of actin. N is solely a function of ATP concentration: 88 ± 24 and 54 ± 22 HMM molecules (mean ± S.D.) at 2 mM and 0.1 mM ATP respectively. Processive sliding of actin filament was observed only when N lay within a minimum lower limit (Nmin) and a maximum upper limit (Nmax) to the number of HMM molecules. When N < Nmin the actin filament diffused away from the surface and processivity was lost and when N > Nmax the filament underwent breakage eventually and could not sustain processive sliding. We postulate this maximum upper limit arises due to increased number of strongly bound myosin heads. PMID:27554800

  1. Maximum limit to the number of myosin II motors participating in processive sliding of actin

    PubMed Central

    Rastogi, Khushboo; Puliyakodan, Mohammed Shabeel; Pandey, Vikas; Nath, Sunil; Elangovan, Ravikrishnan

    2016-01-01

    In this work, we analysed processive sliding and breakage of actin filaments at various heavy meromyosin (HMM) densities and ATP concentrations in IVMA. We observed that with addition of ATP solution, the actin filaments fragmented stochastically; we then determined mean length and velocity of surviving actin filaments post breakage. Average filament length decreased with increase in HMM density at constant ATP, and increased with increase in ATP concentration at constant HMM density. Using density of HMM molecules and length of actin, we estimated the number of HMM molecules per actin filament (N) that participate in processive sliding of actin. N is solely a function of ATP concentration: 88 ± 24 and 54 ± 22 HMM molecules (mean ± S.D.) at 2 mM and 0.1 mM ATP respectively. Processive sliding of actin filament was observed only when N lay within a minimum lower limit (Nmin) and a maximum upper limit (Nmax) to the number of HMM molecules. When N < Nmin the actin filament diffused away from the surface and processivity was lost and when N > Nmax the filament underwent breakage eventually and could not sustain processive sliding. We postulate this maximum upper limit arises due to increased number of strongly bound myosin heads. PMID:27554800

  2. Historical roots of centrosome research: discovery of Boveri's microscope slides in Würzburg.

    PubMed

    Scheer, Ulrich

    2014-09-01

    Boveri's visionary monograph 'Ueber die Natur der Centrosomen' (On the nature of centrosomes) in 1900 was founded primarily on microscopic observations of cleaving eggs of sea urchins and the roundworm parasite Ascaris. As Boveri wrote in the introductory paragraph, his interests were less about morphological aspects of centrosomes, but rather aimed at an understanding of their physiological role during cell division. The remarkable transition from observations of tiny dot-like structures in fixed and sectioned material to a unified theory of centrosome function (which in essence still holds true today) cannot be fully appreciated without examining Boveri's starting material, the histological specimens. It was generally assumed that the microscope slides were lost during the bombing of the Zoological Institute in Würzburg at the end of WWII. Here, I describe the discovery of a number of Boveri's original microscope slides with serial sections of early sea urchin and Ascaris embryos, stained by Heidenhain's iron haematoxylin method. Some slides bear handwritten notes and sketches by Boveri. Evidence is presented that the newly discovered slides are part of the original material used by Boveri for his seminal centrosome monograph. PMID:25047623

  3. Unwinding forward and sliding back: an intermittent unwinding mode of the BLM helicase.

    PubMed

    Wang, Shuang; Qin, Wei; Li, Jing-Hua; Lu, Ying; Lu, Ke-Yu; Nong, Da-Guan; Dou, Shuo-Xing; Xu, Chun-Hua; Xi, Xu-Guang; Li, Ming

    2015-04-20

    There are lines of evidence that the Bloom syndrome helicase, BLM, catalyzes regression of stalled replication forks and disrupts displacement loops (D-loops) formed during homologous recombination (HR). Here we constructed a forked DNA with a 3' single-stranded gap and a 5' double-stranded handle to partly mimic a stalled DNA fork and used magnetic tweezers to study BLM-catalyzed unwinding of the forked DNA. We have directly observed that the BLM helicase may slide on the opposite strand for some distance after duplex unwinding at different forces. For DNA construct with a long hairpin, progressive unwinding of the hairpin is frequently interrupted by strand switching and backward sliding of the enzyme. Quantitative study of the uninterrupted unwinding length (time) has revealed a two-state-transition mechanism for strand-switching during the unwinding process. Mutational studies revealed that the RQC domain plays an important role in stabilizing the helicase/DNA interaction during both DNA unwinding and backward sliding of BLM. Especially, Lys1125 in the RQC domain, a highly conserved amino acid among RecQ helicases, may be involved in the backward sliding activity. We have also directly observed the in vitro pathway that BLM disrupts the mimic stalled replication fork. These results may shed new light on the mechanisms for BLM in DNA repair and homologous recombination.

  4. Planning Robotic Manipulation Strategies for Sliding Objects

    NASA Astrophysics Data System (ADS)

    Peshkin, Michael A.

    Automated planning of grasping or manipulation requires an understanding of both the physics and the geometry of manipulation, and a representation of that knowledge which facilitates the search for successful strategies. We consider manipulation on a level conveyor belt or tabletop, on which a part may slide when touched by a robot. Manipulation plans for a given part must succeed in the face of two types of uncertainty: that of the details of surfaces in contact, and that of the initial configuration of the part. In general the points of contact between the part and the surface it slides on will be unknown, so the motion of the part in response to a push cannot be predicted exactly. Using a simple variational principle (which is derived), we find the set of possible motions of a part for a given push, for all collections of points of contact. The answer emerges as a locus of centers of rotation (CORs). Manipulation plans made using this locus will succeed despite unknown details of contact. Results of experimental tests of the COR loci are presented. Uncertainty in the initial configuration of a part is usually also present. To plan in the presence of uncertainty, configuration maps are defined, which map all configurations of a part before an elementary operation to all possible outcomes, thus encapsulating the physics and geometry of the operation. The configuration map for an operation sequence is a product of configuration maps of elementary operations. Using COR loci we compute configuration maps for elementary sliding operations. Appropriate search techniques are applied to find operation sequences which succeed in the presence of uncertainty in the initial configuration and unknown details of contact. Such operation sequences may be used as parts feeder designs or as manipulation or grasping strategies for robots. As an example we demonstrate the automated design of a class of passive parts feeders consisting of multiple sequential fences across a conveyor

  5. Bi-directional planar slide mechanism

    SciTech Connect

    Bieg, Lothar F.

    2003-11-04

    A bi-directional slide mechanism. A pair of master and slave disks engages opposite sides of the platform. Rotational drivers are connected to master disks so the disks rotate eccentrically about their respective axes of rotation. Opposing slave disks are connected to master disks on opposite sides of the platform by a circuitous mechanical linkage, or are electronically synchronized together using stepper motors, to effect coordinated motion. The synchronized eccentric motion of the pairs of master/slave disks compels smooth linear motion of the platform forwards and backwards without backlash. The apparatus can be incorporated in a MEMS device.

  6. Jupiter System Observer

    NASA Technical Reports Server (NTRS)

    Senske, Dave; Prockter, Louise

    2008-01-01

    This slide presentation reviews the scientific philosophy that is guiding the planning behind the Jupiter System Observer (JSO). The JSO would be a long-term platform for studying Jupiter and the complete Jovian system. The goal is to advance the understanding of the fundamental processes of planetary systems, their formation and evolution.

  7. Towards slide enhancement with the titanium-molybdenum wire?

    PubMed

    Thiry, Pol; Barthélémi, Stéphane

    2010-12-01

    This study aims to improve the tribological properties of titanium-molybdenum wire. Following an analysis of the wire/bracket/ligation friction parameters and an overview of the technological research into means of reducing such friction,we set up several types of surface treatment in the laboratory by physical deposition in the vapor phase and using cold plasma technology. The specimens obtained underwent two types of tribological tests and were then subjected to traction and bending tests in order to determine the variations in their mechanical properties induced by the different types of treatment. For purposes of comparison, all the tests were conducted on untreated wire, TMA® Low-friction® wire and stainless steel wire and with two types of elastomeric ties. We were able to demonstrate some remarkable slide performances obtained using cold plasma nitriding while preserving the mechanical properties. A significant difference was observed relative to the other surface treatments.

  8. Fault stability inferred from granite sliding experiments at hydrothermal conditions

    USGS Publications Warehouse

    Blanpied, M.L.; Lockner, D.A.; Byerlee, J.D.

    1991-01-01

    Seismicity on crustal faults is concentrated in the depth interval 1-3 to 12-15 km. Tse and Rice (1986) suggested that the lower bound on seismicity is due to a switch with increasing temperature from velocity weakening (destabilizing) to velocity strengthening (stabilizing) friction. New data is presented from sliding experiments on granite at elevated T (23?? to 600??C) plus elevated PH2O(100 MPa). Results show velocity strengthening at room temperature, but velocity weakening from 100?? to 350??C (except at 250??). From 350?? to 600?? there are systematic trends from velocity weakening to strong velocity strengthening, and from high to low friction; neither trend was seen in tests on dry granite. The velocity dependence data imply the potential for unstable slip in the interval 100?? to 350??. Using a geotherm to map temperature to depth, this interval closely matches the observed earthquake distribution. -from Authors

  9. Sliding adhesion confers coherent motion to hair cell stereocilia and parallel gating to transduction channels

    PubMed Central

    Karavitaki, K. Domenica; Corey, David P.

    2010-01-01

    When the tip of a hair bundle is deflected by a sensory stimulus, the stereocilia pivot as a unit, producing a shearing displacement between adjacent tips. It is not clear how stereocilia can stick together laterally but still shear. We used dissociated hair cells from the bullfrog saccule and high-speed video imaging to characterize this sliding adhesion. Movement of individual stereocilia was proportional to height, indicating that stereocilia pivot at their basal insertion points. All stereocilia moved by approximately the same angular deflection, and the same motion was observed at 1, 20 and 700 Hz stimulus frequency. Motions were consistent with a geometric model that assumes the stiffness of lateral links holding stereocilia together is >1000 times the pivot stiffness of stereocilia and that these links can slide in the plane of the membrane—in essence, that stereocilia shear without separation. The same motion was observed when bundles were moved perpendicular to the tip links, or when tip links, ankle links and shaft connectors were cut, ruling out these links as the basis for sliding adhesion. Stereocilia rootlets are angled towards the center of the bundle, tending to push stereocilia tips together for small deflections. However, stereocilia remained cohesive for deflections of up to ±35°, ruling out rootlet prestressing as the basis for sliding adhesion. These observations suggest that horizontal top connectors mediate a sliding adhesion. They also indicate that all transduction channels of a hair cell are mechanically in parallel, an arrangement that may enhance amplification in the inner ear. PMID:20610739

  10. 21 CFR 864.3800 - Automated slide stainer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Pathology Instrumentation and Accessories § 864.3800..., cytology, and hematology slides for diagnosis. (b) Classification. Class I (general controls). This...

  11. 21 CFR 864.3800 - Automated slide stainer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Pathology Instrumentation and Accessories § 864.3800..., cytology, and hematology slides for diagnosis. (b) Classification. Class I (general controls). This...

  12. 21 CFR 864.3800 - Automated slide stainer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Pathology Instrumentation and Accessories § 864.3800..., cytology, and hematology slides for diagnosis. (b) Classification. Class I (general controls). This...

  13. 21 CFR 864.3800 - Automated slide stainer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Pathology Instrumentation and Accessories § 864.3800..., cytology, and hematology slides for diagnosis. (b) Classification. Class I (general controls). This...

  14. 21 CFR 864.3800 - Automated slide stainer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Pathology Instrumentation and Accessories § 864.3800..., cytology, and hematology slides for diagnosis. (b) Classification. Class I (general controls). This...

  15. Underwater Sliding Properties: Effect of Slider Shape and Surface Wettability

    NASA Astrophysics Data System (ADS)

    Kirveslahti, A.; Mielonen, K.; Ikonen, K.; Cui, W.; Suvanto, M.; Pakkanen, T. A.

    2016-04-01

    A dynamic test method for the measurement of the underwater sliding properties of model boats has been developed. Surface-modified model boats were examined to assess how the surface wettability properties affect sliding. Along with the surface properties, the influence of the boat shape was considered. We studied various coatings in the contact angle range of 3-162∘ with two model boat shapes. The hydrophobicity of the surfaces influenced the sliding speed of the model boat depending on the boat shape. The method is applicable to study sliding properties of model boats with different surfaces in variable flow conditions.

  16. Second order sliding mode control for a quadrotor UAV.

    PubMed

    Zheng, En-Hui; Xiong, Jing-Jing; Luo, Ji-Liang

    2014-07-01

    A method based on second order sliding mode control (2-SMC) is proposed to design controllers for a small quadrotor UAV. For the switching sliding manifold design, the selection of the coefficients of the switching sliding manifold is in general a sophisticated issue because the coefficients are nonlinear. In this work, in order to perform the position and attitude tracking control of the quadrotor perfectly, the dynamical model of the quadrotor is divided into two subsystems, i.e., a fully actuated subsystem and an underactuated subsystem. For the former, a sliding manifold is defined by combining the position and velocity tracking errors of one state variable, i.e., the sliding manifold has two coefficients. For the latter, a sliding manifold is constructed via a linear combination of position and velocity tracking errors of two state variables, i.e., the sliding manifold has four coefficients. In order to further obtain the nonlinear coefficients of the sliding manifold, Hurwitz stability analysis is used to the solving process. In addition, the flight controllers are derived by using Lyapunov theory, which guarantees that all system state trajectories reach and stay on the sliding surfaces. Extensive simulation results are given to illustrate the effectiveness of the proposed control method.

  17. Slide less pathology”: Fairy tale or reality?

    PubMed Central

    Indu, M; Rathy, R; Binu, MP

    2016-01-01

    Pathology practice is significantly advanced in various frontiers. Therefore, “slide less digital” pathology will not be a mere imagination in near future. Digitalization of histopathological slides (whole slide imaging [WSI]) is possible with the help of whole slide scanner. The WSI has a positive impact not only in routine practice but also in research field, medical education and bioindustry. Even if digital pathology has definitive advantages, its widespread use is not yet possible. As it is an upcoming technology in our field, this article is aimed to discussessential aspects of WSI.

  18. Slide less pathology”: Fairy tale or reality?

    PubMed Central

    Indu, M; Rathy, R; Binu, MP

    2016-01-01

    Pathology practice is significantly advanced in various frontiers. Therefore, “slide less digital” pathology will not be a mere imagination in near future. Digitalization of histopathological slides (whole slide imaging [WSI]) is possible with the help of whole slide scanner. The WSI has a positive impact not only in routine practice but also in research field, medical education and bioindustry. Even if digital pathology has definitive advantages, its widespread use is not yet possible. As it is an upcoming technology in our field, this article is aimed to discussessential aspects of WSI. PMID:27601824

  19. Application of partial sliding mode in guidance problem.

    PubMed

    Shafiei, M H; Binazadeh, T

    2013-03-01

    In this paper, the problem of 3-dimensional guidance law design is considered and a new guidance law based on partial sliding mode technique is presented. The approach is based on the classification of the state variables within the guidance system dynamics with respect to their required stabilization properties. In the proposed law by using a partial sliding mode technique, only trajectories of a part of states variables are forced to reach the partial sliding surfaces and slide on them. The resulting guidance law enables the missile to intercept highly maneuvering targets within a finite interception time. Effectiveness of the proposed guidance law is demonstrated through analysis and simulations.

  20. Vehicle Hybrid Braking Control Using Sliding Mode Control

    NASA Astrophysics Data System (ADS)

    Kasahara, Misawa; Kanai, Yuki; Shiraki, Ryoko; Mori, Yasuchika

    Anti-lock brake system and brake-by-wire are proposed in the vehicle control using a brake, and the braking power is expected to be improved more than ever. The researches such as an application to the ABS of Siliding mode control which considered a actuator dynamics and a hybrid control of the brake using model reference adaptive control are done so far. However, in the former case, speed following that becomes a target exists physically impossible situation by saturation of tire frictional force because only speed following is done. In the latter, the model error is caused because the simulation model and the controller design model are different. Therefore, there is a problem that an accurate follow cannot be done. In this paper, the braking control is performed using the sliding mode control which has high robustness for disturbance that fulfils matching conditions. In so doing, it aims at the achievement of optimal braking control to switch wheel speed following to slip ratio following.

  1. A frictional sliding algorithm for liquid droplets

    NASA Astrophysics Data System (ADS)

    Sauer, Roger A.

    2016-08-01

    This work presents a new frictional sliding algorithm for liquid menisci in contact with solid substrates. In contrast to solid-solid contact, the liquid-solid contact behavior is governed by the contact line, where a contact angle forms and undergoes hysteresis. The new algorithm admits arbitrary meniscus shapes and arbitrary substrate roughness, heterogeneity and compliance. It is discussed and analyzed in the context of droplet contact, but it also applies to liquid films and solids with surface tension. The droplet is modeled as a stabilized membrane enclosing an incompressible medium. The contact formulation is considered rate-independent such that hydrostatic conditions apply. Three distinct contact algorithms are needed to describe the cases of frictionless surface contact, frictionless line contact and frictional line contact. For the latter, a predictor-corrector algorithm is proposed in order to enforce the contact conditions at the contact line and thus distinguish between the cases of advancing, pinning and receding. The algorithms are discretized within a monolithic finite element formulation. Several numerical examples are presented to illustrate the numerical and physical behavior of sliding droplets.

  2. Adaptive Instability Suppression Controls in a Liquid-fueled Combustor

    NASA Technical Reports Server (NTRS)

    Kopasakis, George; DeLaat, John C.

    2002-01-01

    An adaptive control algorithm has been developed for the suppression of combustion thermo-acoustic instabilities. This technique involves modulating the fuel flow in the combustor with a control phase that continuously slides within the stable phase region, in a back and forth motion. The control method is referred to as Adaptive Sliding Phasor Averaged Control (ASPAC). The control method is evaluated against a simplified simulation of the combustion instability. Plans are to validate the control approach against a more physics-based model and an actual experimental combustor rig.

  3. REVIEW: Internal models in sensorimotor integration: perspectives from adaptive control theory

    NASA Astrophysics Data System (ADS)

    Tin, Chung; Poon, Chi-Sang

    2005-09-01

    Internal models and adaptive controls are empirical and mathematical paradigms that have evolved separately to describe learning control processes in brain systems and engineering systems, respectively. This paper presents a comprehensive appraisal of the correlation between these paradigms with a view to forging a unified theoretical framework that may benefit both disciplines. It is suggested that the classic equilibrium-point theory of impedance control of arm movement is analogous to continuous gain-scheduling or high-gain adaptive control within or across movement trials, respectively, and that the recently proposed inverse internal model is akin to adaptive sliding control originally for robotic manipulator applications. Modular internal models' architecture for multiple motor tasks is a form of multi-model adaptive control. Stochastic methods, such as generalized predictive control, reinforcement learning, Bayesian learning and Hebbian feedback covariance learning, are reviewed and their possible relevance to motor control is discussed. Possible applicability of a Luenberger observer and an extended Kalman filter to state estimation problems—such as sensorimotor prediction or the resolution of vestibular sensory ambiguity—is also discussed. The important role played by vestibular system identification in postural control suggests an indirect adaptive control scheme whereby system states or parameters are explicitly estimated prior to the implementation of control. This interdisciplinary framework should facilitate the experimental elucidation of the mechanisms of internal models in sensorimotor systems and the reverse engineering of such neural mechanisms into novel brain-inspired adaptive control paradigms in future.

  4. Significance of grain sliding mechanisms for ductile deformation of rocks

    NASA Astrophysics Data System (ADS)

    Dimanov, A.; Bourcier, M.; Gaye, A.; Héripré, E.; Bornert, M.; Raphanel, J.; Ludwig, W.

    2013-12-01

    Ductile shear zones at depth present polyphase and heterogeneous rocks and multi-scale strain localization patterns. Most strain concentrates in ultramylonitic layers, which exhibit microstructural signatures of several concomitant deformation mechanisms. The latter are either active in volume (dislocation creep), or in the vicinity and along interfaces (grain sliding and solution mass transfer). Because their chronology of appearance and interactions are unclear, inference of the overall rheology seems illusory. We have therefore characterized over a decade the rheology of synthetic lower crustal materials with different compositions and fluid contents, and for various microstructures. Non-Newtonian flow clearly related to dominant dislocation creep. Conversely, Newtonian behavior involved grain sliding mechanisms, but crystal plasticity could be identified as well. In order to clarify the respective roles of these mechanisms we underwent a multi-scale investigation of the ductile deformation of rock analog synthetic halite with controlled microstructures. The mechanical tests were combined with in-situ optical microscopy, scanning electron microscopy and X ray computed tomography, allowing for digital image correlation (DIC) techniques and retrieval of full strain field. Crystal plasticity dominated, as evidenced by physical slip lines and DIC computed slip bands. Crystal orientation mapping allowed to identify strongly active easy glide {110} <110> systems. But, all other slip systems were observed as well, and especially near interfaces, where their activity is necessary to accommodate for the plastic strain incompatibilities between neighboring grains. We also evidenced grain boundary sliding (GBS), which clearly occurred as a secondary, but necessary, accommodation mechanism. The DIC technique allowed the quantification of the relative contribution of each mechanism. The amount of GBS clearly increased with decreasing grain size. Finite element (FE) modeling

  5. Traditional elastic ligatures versus slide ligation system. A morphological evaluation

    PubMed Central

    CONDÒ, R.; CASAGLIA, A.; ARMELLIN, E.; CONDÒ, S.G.; CERRONI, L.

    2013-01-01

    SUMMARY Objective Elastomeric materials play an important role in the orthodontic practice, including the retraction force to move teeth into extraction sites, closing diastemas, selective shifting of the midline and generalized space closure. Frictional resistance and ligating strength of archwire-bracket-ligature complex occurs during utilization of elastomeric and metallic ligatures when orthodontic forces are applicated. The aim of this study was to analyze elastic deformation of three types of elastomeric ligatures, after clinical use. Material and Methods Elastomeric ligatures: ring-shape, transparent, latex ligatures (Leone® S.p.A.), ring-shape, grey, polyurethane ligatures (Micerium® S.p.A.) and grey, polyurethane, Slide low-friction ligatures (Leone® S.p.A.). A total of 9 orthodontic patients undergoing fixed orthodontic therapy were selected. Three specimens were applied, one for each types of ligature, inside the oral cavity of each subject. Samples were kept in the oral cavity for 28 days, ligating 0.16 X 0.22 inches stainless steel archwires to stainless steel premolars brackets (Leone® S.p.A., Sesto Fiorentino, FI, Italy) for Bidimensional technique. After the pre-established time, the systems of ligature were removed and washed. Control group consisted of 9 unused specimens of each ligation type. Each elastomeric ligature was observed under the scanning electron microscope (SEM) to determine variations in size. The archwire-bracket-ligature complex was also analyzed. Results Transparent O-ring ligatures showed significant volumetric and structural changes. The external rounded shape was rather maintained, while the internal shape tended to appear square. Both external and internal diameter significantly increased (p<0.005 and p<0.0001 respectively) while the thickness decreased ( p<0,005) when analyzed with t-test. Polyurethane ring-shape ligatures retained the initial ring design. Both external and internal diameter increased (p<0.0001), while

  6. Depinning-Induced Capillary Wave during the Sliding of a Droplet on a Textured Surface.

    PubMed

    Nguyen, Thanh-Vinh; Tsukagoshi, Takuya; Takahashi, Hidetoshi; Matsumoto, Kiyoshi; Shimoyama, Isao

    2016-09-20

    Surfaces covered with hydrophobic micro-/nanoscale textures can allow water droplets to slide easily because of low contact angle hysteresis. In contrast to the case of a droplet sliding on a smooth surface, when a droplet slides on a textured surface, it must recede from the textures at its rear edge and the resultant depinning events induce a capillary wave on the surface of the droplet. Although this depinning-induced capillary wave can be observed to some extent through high-speed imaging, important parameters of the wave, such as the wavelength and frequency, and the factors that determine these parameters are not fully understood. We report direct measurements of this depinning-induced capillary wave using microelectromechanical systems (MEMS)-based force sensors fabricated on a textured surface. Such sensor measurements reveal the frequency of the vibration occurring on the surface of the droplet, from which it is possible to calculate the wavelength of the capillary wave. We show that the frequency and wavelength of the depinning-induced capillary wave during the sliding of a water droplet on a micropillar array depend upon neither the size of the droplet nor its sliding velocity. However, the frequency (wavelength) decreases (increases) as the pitch of the micropillar array increases. We argue that the wavelength of the depinning-induced capillary wave is equal to the maximum length of the liquid bridges that develop at the micropillars before depinning. This hypothesis is confirmed by comparing the wavelengths obtained from the sensor measurements to the maximum liquid-bridge lengths calculated from observations using a high-speed camera. PMID:27603591

  7. An industry perspective: An update on the adoption of whole slide imaging

    PubMed Central

    Montalto, Michael C.

    2016-01-01

    This manuscript is an adaptation of the closing keynote presentation of the Digital Pathology Association Pathology Visions Conference 2015 in Boston, MA, USA. In this presentation, analogies are drawn between the adoption of whole slide imaging (WSI) and other mainstream digital technologies, including digital music and books. In doing so, it is revealed that the adoption of seemingly similar digital technologies does not follow the same adoption profiles and that understanding the unique aspects of value for each customer segment is critical. Finally, a call to action is given to academia and industry to study the value that WSI brings to the global healthcare community. PMID:27141323

  8. Chromosomal Replication Dynamics and Interaction with the β Sliding Clamp Determine Orientation of Bacterial Transposable Elements

    PubMed Central

    Gómez, Manuel J.; Díaz-Maldonado, Héctor; González-Tortuero, Enrique; López de Saro, Francisco J.

    2014-01-01

    Insertion sequences (ISs) are small transposable elements widespread in bacterial genomes, where they play an essential role in chromosome evolution by stimulating recombination and genetic flow. Despite their ubiquity, it is unclear how ISs interact with the host. Here, we report a survey of the orientation patterns of ISs in bacterial chromosomes with the objective of gaining insight into the interplay between ISs and host chromosomal functions. We find that a significant fraction of IS families present a consistent and family-specific orientation bias with respect to chromosomal DNA replication, especially in Firmicutes. Additionally, we find that the transposases of up to nine different IS families with different transposition pathways interact with the β sliding clamp, an essential replication factor, suggesting that this is a widespread mechanism of interaction with the host. Although we find evidence that the interaction with the β sliding clamp is common to all bacterial phyla, it also could explain the observed strong orientation bias found in Firmicutes, because in this group β is asymmetrically distributed during synthesis of the leading or lagging strands. Besides the interaction with the β sliding clamp, other asymmetries also play a role in the biased orientation of some IS families. The utilization of the highly conserved replication sliding clamps suggests a mechanism for host regulation of IS proliferation and also a universal platform for IS dispersal and transmission within bacterial populations and among phylogenetically distant species. PMID:24614824

  9. Impact of Atomic Corrugation on Sliding Friction as Probed by QCM

    NASA Astrophysics Data System (ADS)

    Coffey, Tonya; Lee, Sang; Krim, Jacqueline

    2004-03-01

    At the atomic scale, friction is believed to originate primarily via sliding induced excitation of phonons. [1] Theoretical predictions of the magnitude of phononic dissipation have been related to the atomic corrugation of the adsorbate/substrate potential. [2] Braun and colleagues [3] measured a corrugation of 1.9 meV for xenon on a copper(111) surface using helium atom scattering. Using the Quartz Crystal Microbalance (QCM), we have measured the sliding friction of Xe/Cu(111) adsorbed at 77 K. The QCM probe of sliding friction is the sliptime, which measures the slippage of the adsorbate atop the oscillating surface of the QCM. For monolayer coverages, we observed a sliptime of 10 ns for Xe/Cu(111). We also discuss theoretical predictions for the impact of atomic corrugation on sliding friction. [1] Fundamentals of Friction; Macroscopic and Microscopic Processes, ed. I.L. Singer and H.M. Pollock, Kluwer, Dordrecht (1992). [2] M. Cieplak, E.D. Smith, and M.O. Robbins, Science 265 (1994) 1209. [3] J. Braun et al., PRL 80 (1998) 125.

  10. Sliding mechanics of coated composite wires and the development of an engineering model for binding.

    PubMed

    Zufall, S W; Kusy, R P

    2000-02-01

    A tribological (friction and wear) study, which was designed to simulate clinical sliding mechanics, was conducted as part of an effort to determine the suitability of poly(chloro-p-xylylene) coatings for composite orthodontic archwires. Prototype composite wires, having stiffnesses similar to those of current initial and intermediate alignment wires, were tested against stainless steel and ceramic brackets in the passive and active configurations (with and without angulation). Kinetic coefficient of friction values, which were determined to quantify sliding resistances as functions of the normal forces of ligation, had a mean that was 72% greater than uncoated wire couples at 0.43. To improve analysis of the active configuration, a mathematical model was developed that related bracket angulation, bracket width, interbracket distance, wire geometry, and wire elastic modulus to sliding resistance. From this model, kinetic coefficients of binding were determined to quantify sliding resistances as functions of the normal forces of binding. The mean binding coefficient was the same as that of uncoated wire couples at 0.42. Although penetrations through the coating were observed on many specimens, the glass-fiber reinforcement within the composite wires was undamaged for all conditions tested. This finding implies that the risk of glass fiber release during clinical use would be eliminated by the coating. In addition, the frictional and binding coefficients were still within the limits outlined by conventional orthodontic wire-bracket couples. Consequently, the coatings were regarded as an improvement to the clinical acceptability of composite orthodontic archwires.

  11. Computer simulations of particle-bubble interactions and particle sliding using Discrete Element Method.

    PubMed

    Maxwell, R; Ata, S; Wanless, E J; Moreno-Atanasio, R

    2012-09-01

    Three dimensional Discrete Element Method (DEM) computer simulations have been carried out to analyse the kinetics of collision of multiple particles against a stationary bubble and the sliding of the particles over the bubble surface. This is the first time that a computational analysis of the sliding time and particle packing arrangements of multiple particles on the surface of a bubble has been carried out. The collision kinetics of monodisperse (33 μm in radius) and polydisperse (12-33 μm in radius) particle systems have been analysed in terms of the time taken by 10%, 50% and 100% of the particles to collide against the bubble. The dependencies of these collision times on the strength of hydrophobic interactions follow relationships close to power laws. However, minimal sensitivity of the collision times to particle size was found when linear and square relationships of the hydrophobic force with particles radius were considered. The sliding time for single particles has corroborated published theoretical expressions. Finally, a good qualitative comparison with experiments has been observed with respect to the particle packing at the bottom of the bubble after sliding demonstrating the usefulness of computer simulations in the studies of particle-bubble systems.

  12. Sliding-Mode Control Applied for Robust Control of a Highly Unstable Aircraft

    NASA Technical Reports Server (NTRS)

    Vetter, Travis Kenneth

    2002-01-01

    An investigation into the application of an observer based sliding mode controller for robust control of a highly unstable aircraft and methods of compensating for actuator dynamics is performed. After a brief overview of some reconfigurable controllers, sliding mode control (SMC) is selected because of its invariance properties and lack of need for parameter identification. SMC is reviewed and issues with parasitic dynamics, which cause system instability, are addressed. Utilizing sliding manifold boundary layers, the nonlinear control is converted to a linear control and sliding manifold design is performed in the frequency domain. An additional feedback form of model reference hedging is employed which is similar to a prefilter and has large benefits to system performance. The effects of inclusion of actuator dynamics into the designed plant is heavily investigated. Multiple Simulink models of the full longitudinal dynamics and wing deflection modes of the forward swept aero elastic vehicle (FSAV) are constructed. Additionally a linear state space models to analyze effects from various system parameters. The FSAV has a pole at +7 rad/sec and is non-minimum phase. The use of 'model actuators' in the feedback path, and varying there design, is heavily investigated for the resulting effects on plant robustness and tolerance to actuator failure. The use of redundant actuators is also explored and improved robustness is shown. All models are simulated with severe failure and excellent tracking, and task dependent handling qualities, and low pilot induced oscillation tendency is shown.

  13. Plastic deformation and wear process at a surface during unlubricated sliding

    NASA Technical Reports Server (NTRS)

    Yamamoto, T.; Buckley, D. H.

    1983-01-01

    The plastic deformation and wear of a 304 stainless steel surface sliding against an aluminum oxide rider with a spherical surface (the radius of curvature: 1.3 cm) were observed by using scanning electron and optical microscopes. Experiments were conducted in a vacuum of one million Pa and in an environment of fifty thousandth Pa of chlorine gas at 25 C. The load was 500 grams and the sliding velocity was 0.5 centimeter per second. The deformed surface layer which accumulates and develops successively is left behind the rider, and step shaped proturbances are developed even after single pass sliding under both environmental conditions. A fully developed surface layer is gradually torn off leaving a characteristic pattern. The mechanism for tearing away of the surface layer from the contact area and sliding track contour is explained assuming the simplified process of material removal based on the adhesion theory for the wear of materials. Previously announced in STAR as N82-32735

  14. The empirical evaluation and examination of breechface markings on ten consecutively manufactured pistol slides

    NASA Astrophysics Data System (ADS)

    Huang, Sascha

    Previously published research and case studies exist pertaining to consecutively manufactured tool marks and the individuality of those markings on tools. This study seeked to assess the Association of Firearm and Tool Mark Examiners (AFTE) Theory of Identification and provide additional research into the investigation of characteristics potentially viewed on the breechfaces of pistol slides. The researcher obtained ten consecutively manufactured Ruger LCP .380 Auto slides for examination. The tool marks exhibited on the breechfaces were macroscopically examined, evaluated in terms of potential for the transfer of subclass characteristics, and examined for the presence of individual characteristics. This research indicated whether breechface markings were accorded to their respective slide or if misidentification by examiners was possible. The first phase of this study was in further validating the AFTE Theory of Identification through generation of a test for AFTE members. This test required examiners to distinguish between subclass and individual characteristics, identify cartridge cases to their respective slide, and determine whether there was potential for misidentification of breechface markings due to subclass carryover. The second phase observed the differences and similarities of examiner ability and IBISRTM BRASSTRAX-3D(TM) ability to identify cartridge cases. This study might also function as a test for firearm and tool mark examiners to utilize in their laboratories as a training exercise related to consecutively manufactured breechfaces. The research findings might also facilitate the development of error rates pertaining to this study.

  15. Experimental adaptive Bayesian tomography

    NASA Astrophysics Data System (ADS)

    Kravtsov, K. S.; Straupe, S. S.; Radchenko, I. V.; Houlsby, N. M. T.; Huszár, F.; Kulik, S. P.

    2013-06-01

    We report an experimental realization of an adaptive quantum state tomography protocol. Our method takes advantage of a Bayesian approach to statistical inference and is naturally tailored for adaptive strategies. For pure states, we observe close to N-1 scaling of infidelity with overall number of registered events, while the best nonadaptive protocols allow for N-1/2 scaling only. Experiments are performed for polarization qubits, but the approach is readily adapted to any dimension.

  16. Robust fault tolerant control based on sliding mode method for uncertain linear systems with quantization.

    PubMed

    Hao, Li-Ying; Yang, Guang-Hong

    2013-09-01

    This paper is concerned with the problem of robust fault-tolerant compensation control problem for uncertain linear systems subject to both state and input signal quantization. By incorporating novel matrix full-rank factorization technique with sliding surface design successfully, the total failure of certain actuators can be coped with, under a special actuator redundancy assumption. In order to compensate for quantization errors, an adjustment range of quantization sensitivity for a dynamic uniform quantizer is given through the flexible choices of design parameters. Comparing with the existing results, the derived inequality condition leads to the fault tolerance ability stronger and much wider scope of applicability. With a static adjustment policy of quantization sensitivity, an adaptive sliding mode controller is then designed to maintain the sliding mode, where the gain of the nonlinear unit vector term is updated automatically to compensate for the effects of actuator faults, quantization errors, exogenous disturbances and parameter uncertainties without the need for a fault detection and isolation (FDI) mechanism. Finally, the effectiveness of the proposed design method is illustrated via a model of a rocket fairing structural-acoustic.

  17. Metastability, Adaptability and Memory in Charge Density Waves. I. Resetting Property

    NASA Astrophysics Data System (ADS)

    Ito, Hiroyuki

    1989-06-01

    We give a possible interpretation of the adaptation of the charge density waves (CDW) to the pulse fields, which is observed to be accompanied with the memory of the width of the applied pulses (Ido step memory effect). When the identical pulse fields are repeatedly applied, successive state transitions are induced among metastable states. By the numerical simulations with the use of the Fukuyama-Lee-Rice model, we have found that only the state can be a fixed point in the transitions where the sliding motion under the pulse field satisfies a certain condition. Selecting the adequate state for a fixed point, the system adapts itself to the applied pulse width so that the current response has a common regularity regardless of the pulse width.

  18. Cancer Digital Slide Archive: an informatics resource to support integrated in silico analysis of TCGA pathology data

    PubMed Central

    Gutman, David A; Cobb, Jake; Somanna, Dhananjaya; Park, Yuna; Wang, Fusheng; Kurc, Tahsin; Saltz, Joel H; Brat, Daniel J; Cooper, Lee A D

    2013-01-01

    Background The integration and visualization of multimodal datasets is a common challenge in biomedical informatics. Several recent studies of The Cancer Genome Atlas (TCGA) data have illustrated important relationships between morphology observed in whole-slide images, outcome, and genetic events. The pairing of genomics and rich clinical descriptions with whole-slide imaging provided by TCGA presents a unique opportunity to perform these correlative studies. However, better tools are needed to integrate the vast and disparate data types. Objective To build an integrated web-based platform supporting whole-slide pathology image visualization and data integration. Materials and methods All images and genomic data were directly obtained from the TCGA and National Cancer Institute (NCI) websites. Results The Cancer Digital Slide Archive (CDSA) produced is accessible to the public (http://cancer.digitalslidearchive.net) and currently hosts more than 20 000 whole-slide images from 22 cancer types. Discussion The capabilities of CDSA are demonstrated using TCGA datasets to integrate pathology imaging with associated clinical, genomic and MRI measurements in glioblastomas and can be extended to other tumor types. CDSA also allows URL-based sharing of whole-slide images, and has preliminary support for directly sharing regions of interest and other annotations. Images can also be selected on the basis of other metadata, such as mutational profile, patient age, and other relevant characteristics. Conclusions With the increasing availability of whole-slide scanners, analysis of digitized pathology images will become increasingly important in linking morphologic observations with genomic and clinical endpoints. PMID:23893318

  19. Recurrent Pleistocene sub-marine slide events on the south Vøring Plateau, mid-Norwegian continental margin

    NASA Astrophysics Data System (ADS)

    Hjelstuen, B.; Skaug, M.; Haflidason, H.

    2009-12-01

    Throughout the Pleistocene the sediment input and depositional environments on the continental slope off Norway have been strongly controlled by variability in the ocean circulation, glaciations and sea-level changes. Repeated occurrence of shelf edge glaciations along the whole NW European margin, from Ireland to Svalbard, started at Marine Isotope Stage 12 (c. 0.5 Ma). During these periods, fast moving ice streams crossed the continental shelf on a number of locations, and large submarine fans and prograding wedges accumulated on the continental slope. During glacial maximums and in the early phases of the deglaciations high sedimentation rates, >2000 cm/ka, characterised the Norwegian continental margin. Within these depositional environments more than 30 large-scale mass failures have been identified. Here, we report on three slide events on the south Vøring Plateau, on the mid-Norwegian margin. These slides have affected an area between 2900 and 12000 km2 and involved 580-2400 km3 of sediments, noting that the slide debrites left by the failure events reach a maximum thickness of c. 150 m. For comparison the Holocene Storegga Slide, considered the largest exposed sub-marine slide in the world today, mobilized c. 2500-3500 km3 of masses and affected an area of c. 95 000 km2. The Vøring Plateau sub-marine slides are most likely younger than 0.5 Ma, thus occurring in a time period of repeated ice sheet growth to the shelf edge and high accumulation rates. The failures have occurred within an area dominated by gradients less than 1 degree, and observation of long run-out distances indicate that hydroplaning was important during slide development. Our multichannel seismic profiles further show that gas hydrate bearing sediments are observed on the mid-Norwegian continental margin. Thus, dissociation of gas hydrates and high sedimentation rates may have promoted conditions for failures to occur.

  20. In situ TEM characterization of shear-stress-induced interlayer sliding in the cross section view of molybdenum disulfide.

    PubMed

    Oviedo, Juan Pablo; KC, Santosh; Lu, Ning; Wang, Jinguo; Cho, Kyeongjae; Wallace, Robert M; Kim, Moon J

    2015-02-24

    The experimental study of interlayer sliding at the nanoscale in layered solids has been limited thus far by the incapability of mechanical and imaging probes to simultaneously access sliding interfaces and overcome through mechanical stimulus the van der Waals and Coulombic interactions holding the layers in place. For this purpose, straightforward methods were developed to achieve interlayer sliding in molybdenum disulfide (MoS2) while under observation within a transmission electron microscope. A method to manipulate, tear, and slide free-standing atomic layers of MoS2 is demonstrated by electrostatically coupling it to an oxidized tungsten probe attached to a micromanipulator at a bias above ±7 V. A first-principles model of a MoS2 bilayer polarized by a normal electric field of 5 V/nm, emanating from the tip, demonstrates the appearance of a periodic negative sliding potential energy barrier when the layers slide into the out-of-registry stacking configuration, hinting at electrostatic gating as a means of modifying the interlayer tribology to facilitate shear exfoliation. A method to shear focused ion beam prepared MoS2 cross section samples using a nanoindenter force sensor is also demonstrated, allowing both the observation and force measurement of its interlayer dynamics during shear-induced sliding. From this experiment, the zero normal load shear strength of MoS2 can be directly obtained: 25.3 ± 0.6 MPa. These capabilities enable the site-specific mechanical testing of dry lubricant-based nanoelectromechanical devices and can lead to a better understanding of the atomic mechanisms from which the interlayer tribology of layered materials originates. PMID:25494557

  1. PPP Sliding Window Algorithm and Its Application in Deformation Monitoring.

    PubMed

    Song, Weiwei; Zhang, Rui; Yao, Yibin; Liu, Yanyan; Hu, Yuming

    2016-01-01

    Compared with the double-difference relative positioning method, the precise point positioning (PPP) algorithm can avoid the selection of a static reference station and directly measure the three-dimensional position changes at the observation site and exhibit superiority in a variety of deformation monitoring applications. However, because of the influence of various observing errors, the accuracy of PPP is generally at the cm-dm level, which cannot meet the requirements needed for high precision deformation monitoring. For most of the monitoring applications, the observation stations maintain stationary, which can be provided as a priori constraint information. In this paper, a new PPP algorithm based on a sliding window was proposed to improve the positioning accuracy. Firstly, data from IGS tracking station was processed using both traditional and new PPP algorithm; the results showed that the new algorithm can effectively improve positioning accuracy, especially for the elevation direction. Then, an earthquake simulation platform was used to simulate an earthquake event; the results illustrated that the new algorithm can effectively detect the vibrations change of a reference station during an earthquake. At last, the observed Wenchuan earthquake experimental results showed that the new algorithm was feasible to monitor the real earthquakes and provide early-warning alerts. PMID:27241172

  2. PPP Sliding Window Algorithm and Its Application in Deformation Monitoring

    PubMed Central

    Song, Weiwei; Zhang, Rui; Yao, Yibin; Liu, Yanyan; Hu, Yuming

    2016-01-01

    Compared with the double-difference relative positioning method, the precise point positioning (PPP) algorithm can avoid the selection of a static reference station and directly measure the three-dimensional position changes at the observation site and exhibit superiority in a variety of deformation monitoring applications. However, because of the influence of various observing errors, the accuracy of PPP is generally at the cm-dm level, which cannot meet the requirements needed for high precision deformation monitoring. For most of the monitoring applications, the observation stations maintain stationary, which can be provided as a priori constraint information. In this paper, a new PPP algorithm based on a sliding window was proposed to improve the positioning accuracy. Firstly, data from IGS tracking station was processed using both traditional and new PPP algorithm; the results showed that the new algorithm can effectively improve positioning accuracy, especially for the elevation direction. Then, an earthquake simulation platform was used to simulate an earthquake event; the results illustrated that the new algorithm can effectively detect the vibrations change of a reference station during an earthquake. At last, the observed Wenchuan earthquake experimental results showed that the new algorithm was feasible to monitor the real earthquakes and provide early-warning alerts. PMID:27241172

  3. PPP Sliding Window Algorithm and Its Application in Deformation Monitoring

    NASA Astrophysics Data System (ADS)

    Song, Weiwei; Zhang, Rui; Yao, Yibin; Liu, Yanyan; Hu, Yuming

    2016-05-01

    Compared with the double-difference relative positioning method, the precise point positioning (PPP) algorithm can avoid the selection of a static reference station and directly measure the three-dimensional position changes at the observation site and exhibit superiority in a variety of deformation monitoring applications. However, because of the influence of various observing errors, the accuracy of PPP is generally at the cm-dm level, which cannot meet the requirements needed for high precision deformation monitoring. For most of the monitoring applications, the observation stations maintain stationary, which can be provided as a priori constraint information. In this paper, a new PPP algorithm based on a sliding window was proposed to improve the positioning accuracy. Firstly, data from IGS tracking station was processed using both traditional and new PPP algorithm; the results showed that the new algorithm can effectively improve positioning accuracy, especially for the elevation direction. Then, an earthquake simulation platform was used to simulate an earthquake event; the results illustrated that the new algorithm can effectively detect the vibrations change of a reference station during an earthquake. At last, the observed Wenchuan earthquake experimental results showed that the new algorithm was feasible to monitor the real earthquakes and provide early-warning alerts.

  4. Lecture Handouts of Projected Slides in a Medical Course.

    ERIC Educational Resources Information Center

    Amato, Dominick; Quirt, Ian

    1991-01-01

    In a third-year medical school hematology course, handouts reproducing all or most of the 35mm slides used during the lecture are given at the beginning of class. The slides are reproduced on the left, with room for note-taking on the right. Despite some disadvantages, the method is seen as helpful. (Author/MSE)

  5. 45 CFR 98.42 - Sliding fee scales.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Welfare Department of Health and Human Services GENERAL ADMINISTRATION CHILD CARE AND DEVELOPMENT FUND Program Operations (Child Care Services)-Lead Agency and Provider Requirements § 98.42 Sliding fee scales... provides for cost sharing by families that receive CCDF child care services. (b) A sliding fee...

  6. 45 CFR 98.42 - Sliding fee scales.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION CHILD CARE AND DEVELOPMENT FUND Program Operations (Child Care Services)-Lead Agency and Provider Requirements § 98.42 Sliding fee scales... provides for cost sharing by families that receive CCDF child care services. (b) A sliding fee...

  7. 45 CFR 98.42 - Sliding fee scales.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION CHILD CARE AND DEVELOPMENT FUND Program Operations (Child Care Services)-Lead Agency and Provider Requirements § 98.42 Sliding fee scales... provides for cost sharing by families that receive CCDF child care services. (b) A sliding fee...

  8. 45 CFR 98.42 - Sliding fee scales.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION CHILD CARE AND DEVELOPMENT FUND Program Operations (Child Care Services)-Lead Agency and Provider Requirements § 98.42 Sliding fee scales... provides for cost sharing by families that receive CCDF child care services. (b) A sliding fee...

  9. 45 CFR 98.42 - Sliding fee scales.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION CHILD CARE AND DEVELOPMENT FUND Program Operations (Child Care Services)-Lead Agency and Provider Requirements § 98.42 Sliding fee scales... provides for cost sharing by families that receive CCDF child care services. (b) A sliding fee...

  10. Determining the Ecosystem Services Important for Urban Landscapes-Slides

    EPA Science Inventory

    This presentation consists of introductory slides on ecosystem services in urban landscapes and then a discussion of two case studies concerning the provision of water quality in urban landscapes. The introductory slides will explore the range of ecosystem services provided by u...

  11. Optimizing Student Learning: Examining the Use of Presentation Slides

    ERIC Educational Resources Information Center

    Strauss, Judy; Corrigan, Hope; Hofacker, Charles F.

    2011-01-01

    Sensory overload and split attention result in reduced learning when instructors read slides with bullet points and complex graphs during a lecture. Conversely, slides containing relevant visual elements, when accompanied by instructor narration, use both the visual and verbal channels of a student's working memory, thus improving the chances of…

  12. The Easy Way to Create Computer Slide Shows.

    ERIC Educational Resources Information Center

    Anderson, Mary Alice

    1995-01-01

    Discusses techniques for creating computer slide shows. Topics include memory; format; color use; HyperCard and CD-ROM; font styles and sizes; graphs and graphics; the slide show option; special effects; and tips for effective presentation. (Author/AEF)

  13. A Simple Measurement of the Sliding Friction Coefficient

    ERIC Educational Resources Information Center

    Gratton, Luigi M.; Defrancesco, Silvia

    2006-01-01

    We present a simple computer-aided experiment for investigating Coulomb's law of sliding friction in a classroom. It provides a way of testing the possible dependence of the friction coefficient on various parameters, such as types of materials, normal force, apparent area of contact and sliding velocity.

  14. 49 CFR 229.115 - Slip/slide alarms.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... sliding wheels on powered axles under power. When two or more locomotives are coupled in multiple or remote control, the wheel slip/slide alarm of each locomotive shall be shown in the cab of the... road service, or continue in road service following a daily inspection, unless the wheel...

  15. 49 CFR 229.115 - Slip/slide alarms.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... sliding wheels on powered axles under power. When two or more locomotives are coupled in multiple or remote control, the wheel slip/slide alarm of each locomotive shall be shown in the cab of the... road service, or continue in road service following a daily inspection, unless the wheel...

  16. 49 CFR 229.115 - Slip/slide alarms.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... sliding wheels on powered axles under power. When two or more locomotives are coupled in multiple or remote control, the wheel slip/slide alarm of each locomotive shall be shown in the cab of the... road service, or continue in road service following a daily inspection, unless the wheel...

  17. Qualification test unit slide stainer (Beckman P/N 673753)

    NASA Technical Reports Server (NTRS)

    Bernier, P. S.

    1972-01-01

    Specifications for a slide stainer unit for the Skylab program are presented. The qualification test slide stainer was designed to be a self-contained system capable of performing an eight-step Gram stain of microorganisms and a Wright's stain of blood smears.

  18. A Transformational Approach to Slip-Slide Factoring

    ERIC Educational Resources Information Center

    Steckroth, Jeffrey

    2015-01-01

    In this "Delving Deeper" article, the author introduces the slip-slide method for solving Algebra 1 mathematics problems. This article compares the traditional method approach of trial and error to the slip-slide method of factoring. Tools that used to be taken for granted now make it possible to investigate relationships visually,…

  19. 8. Photocopy of original USRS glass plate slide (from original ...

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

    8. Photocopy of original USRS glass plate slide (from original slide on file at National Archives, Rocky Mountain Region, Denver, Colorado) Photographer unknown, ca. 1908 The diversion weir of the Okanogan National Irrigation Project - Salmon Creek Diversion Dam, Salmon Creek, Okanogan, Okanogan County, WA

  20. AFRD WAREHOUSE, WEST SIDE DETAIL OF ALTERED SLIDING DOORS, FACING ...

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

    AFRD WAREHOUSE, WEST SIDE DETAIL OF ALTERED SLIDING DOORS, FACING EAST. WEATHER COVER OVER RAIL IS ORIGINAL. SHEET METAL SIDING HAS BEEN INSERTED BETWEEN TWO HALVES OF SLIDING DOORS. - Minidoka Relocation Center Warehouse, 111 South Fir Street, Shoshone, Lincoln County, ID

  1. Detection of felt tip markers on microscope slides

    NASA Astrophysics Data System (ADS)

    Friedrich, David; Meyer-Ebrecht, Dietrich; Böcking, Alfred; Merhof, Dorit

    2014-03-01

    Sensitivity and specificity of conventional cytological methods for cancer diagnosis can be raised significantly by applying further adjuvant cytological methods. To this end, the pathologist marks regions of interest (ROI) with a felt tip pen on the microscope slide for further analysis. This paper presents algorithms for the automated detection of these ROIs, which enables further automated processing of these regions by digital pathology solutions and image analysis. For this purpose, an overview scan is obtained at low magnification. Slides from different manufacturers need to be treated, as they might contain certain regions which need to be excluded from the analysis. Therefore the slide type is identified first. Subsequently, the felt tip marks are detected automatically, and gaps appearing in the case of ROIs which have been drawn incompletely are closed. Based on the marker detection, the ROIs are obtained. The algorithms have been optimized on a training set of 82 manually annotated images. On the test set, the slide types of all but one out of 81 slides were identified correctly. A sensitivity of 98.31% and a positive predictive value of 97.48% were reached for the detection of ROIs. In combination with a slide loader or a whole slide imaging scanner as well as automated image analysis, this enables fully automated batch processing of slides.

  2. A Computer System for Making Quick and Economical Color Slides.

    ERIC Educational Resources Information Center

    Pryor, Harold George

    1986-01-01

    A computer-based method for producing 35mm color slides has been used in Ohio State University's College of Dentistry. The method can produce both text and slides in less than two hours, providing substantial flexibility in planning and revising visual presentations. (Author/MLW)

  3. [Whole slide imaging technology: from digitization to online applications].

    PubMed

    Ameisen, David; Le Naour, Gilles; Daniel, Christel

    2012-11-01

    As e-health becomes essential to modern care, whole slide images (virtual slides) are now an important clinical, teaching and research tool in pathology. Virtual microscopy consists of digitizing a glass slide by acquiring hundreds of tiles of regions of interest at different zoom levels and assembling them into a structured file. This gigapixel image can then be remotely viewed over a terminal, exactly the way pathologists use a microscope. In this article, we will first describe the key elements of this technology, from the acquisition, using a scanner or a motorized microscope, to the broadcasting of virtual slides through a local or distant viewer over an intranet or Internet connection. As virtual slides are now commonly used in virtual classrooms, clinical data and research databases, we will highlight the main issues regarding its uses in modern pathology. Emphasis will be made on quality assurance policies, standardization and scaling.

  4. Teaching Veterinary Histopathology: A Comparison of Microscopy and Digital Slides.

    PubMed

    Brown, Peter J; Fews, Debra; Bell, Nick J

    2016-01-01

    Virtual microscopy using digitized slides has become more widespread in teaching in recent years. There have been no direct comparisons of the use of virtual microscopy and the use of microscopes and glass slides. Third-year veterinary students from two different schools completed a simple objective test, covering aspects of histology and histopathology, before and after a practical class covering relevant material presented as either glass slides viewed with a microscope or as digital slides. There was an overall improvement in performance by students at both veterinary schools using both practical formats. Neither format was consistently better than the other, and neither school consistently outperformed the other. In a comparison of student appraisal of use of digital slides and microscopes, the digital technology was identified as having many advantages.

  5. Sliding wear studies using acoustic emission

    NASA Astrophysics Data System (ADS)

    Lingard, S.; Yu, C. W.; Yau, C. F.

    1993-04-01

    Deformation processes in solids, such as dislocation movements under plastic flow, crack propagation and void crushing, produce stress waves at ultrasonic frequencies, usually described as acoustic emission (AE), which can be detected by sensitive instruments and which are related to the severity and nature of the deformations. The paper discusses the characteristics of the stress waves and their variation with wear rates, wear regimes, and friction forces, as determined during laboratory experiments on metallic specimens in relative sliding motion, both unlubricated and with elastohydrodynamic lubrication. It is shown that there are systematic relationships between the acoustic emissions, the wear rates, the frictional work inputs and established tribological contact variables. The predominant frequencies of the emissions are also evaluated and considered in relation to the materials and wear conditions.

  6. Sliding Mode Control of Steerable Needles

    PubMed Central

    Rucker, D. Caleb; Das, Jadav; Gilbert, Hunter B.; Swaney, Philip J.; Miga, Michael I.; Sarkar, Nilanjan; Webster, Robert J.

    2014-01-01

    Steerable needles can potentially increase the accuracy of needle-based diagnosis and therapy delivery, provided they can be adequately controlled based on medical image information. We propose a novel sliding mode control law that can be used to deliver the tip of a flexible asymmetric-tipped needle to a desired point, or to track a desired trajectory within tissue. The proposed control strategy requires no a priori knowledge of model parameters, has bounded input speeds, and requires little computational resources. We show that if the standard nonholonomic model for tip-steered needles holds, then the control law will converge to desired targets in a reachable workspace, within a tolerance that can be defined by the control parameters. Experimental results validate the control law for target points and trajectory following in phantom tissue and ex vivo liver. Experiments with targets that move during insertion illustrate robustness to disturbances caused by tissue deformation. PMID:25400527

  7. Sliding seal materials for adiabatic engines

    NASA Technical Reports Server (NTRS)

    Lankford, J.

    1985-01-01

    The sliding friction coefficients and wear rates of promising carbide, oxide, and nitride materials were measured under temperature, environmental, velocity, loading conditions that are representative of the adiabatic engine environment. In order to provide guidance needed to improve materials for this application, the program stressed fundamental understanding of the mechanisms involved in friction and wear. Microhardness tests were performed on the candidate materials at elevated temperatures, and in atmospheres relevant to the piston seal application, and optical and electron microscopy were used to elucidate the micromechanisms of wear following wear testing. X-ray spectroscopy was used to evaluate interface/environment interactions which seemed to be important in the friction and wear process. Electrical effects in the friction and wear processes were explored in order to evaluate the potential usefulness of such effects in modifying the friction and wear rates in service. However, this factor was found to be of negligible significance in controlling friction and wear.

  8. Sliding Mode Control of Steerable Needles.

    PubMed

    Rucker, D Caleb; Das, Jadav; Gilbert, Hunter B; Swaney, Philip J; Miga, Michael I; Sarkar, Nilanjan; Webster, Robert J

    2013-10-01

    Steerable needles can potentially increase the accuracy of needle-based diagnosis and therapy delivery, provided they can be adequately controlled based on medical image information. We propose a novel sliding mode control law that can be used to deliver the tip of a flexible asymmetric-tipped needle to a desired point, or to track a desired trajectory within tissue. The proposed control strategy requires no a priori knowledge of model parameters, has bounded input speeds, and requires little computational resources. We show that if the standard nonholonomic model for tip-steered needles holds, then the control law will converge to desired targets in a reachable workspace, within a tolerance that can be defined by the control parameters. Experimental results validate the control law for target points and trajectory following in phantom tissue and ex vivo liver. Experiments with targets that move during insertion illustrate robustness to disturbances caused by tissue deformation.

  9. DPS Discovery Slide Sets for the Introductory Astronomy Instructor

    NASA Astrophysics Data System (ADS)

    Meinke, Bonnie K.; Jackson, Brian; Buxner, Sanlyn; Horst, Sarah; Brain, David; Schneider, Nicholas M.

    2016-10-01

    The DPS actively supports the E/PO needs of the society's membership, including those at the front of the college classroom. The DPS Discovery Slide Sets are an opportunity for instructors to put the latest planetary science into their lectures and for scientists to get their exciting results to college students.In an effort to keep the astronomy classroom apprised of the fast moving field of planetary science, the Division for Planetary Sciences (DPS) has developed "DPS Discoveries", which are 3-slide presentations that can be incorporated into college lectures. The slide sets are targeted at the Introductory Astronomy undergraduate level. Each slide set consists of three slides which cover a description of the discovery, a discussion of the underlying science, and a presentation of the big picture implications of the discovery, with a fourth slide that includes links to associated press releases, images, and primary sources. Topics span all subdisciplines of planetary science, and 26 sets are available in Farsi and Spanish. We intend for these slide sets to help Astronomy 101 instructors include new developments (not yet in their textbooks) into the broader context of the course. If you need supplemental material for your classroom, please checkout the archived collection: http://dps.aas.org/education/dpsdiscMore slide sets are now in development and will be available soon! In the meantime, we seek input, feedback, and help from the DPS membership to add fresh slide sets to the series and to connect the college classroom to YOUR science. It's easy to get involved – we'll provide a content template, tips and tricks for a great slide set, and pedagogy reviews. Talk to a coauthor to find out how you can disseminate your science or get involved in E/PO with your contributions.

  10. Energy Partitioning during Frictional Sliding at Coseismic Slip Rates

    NASA Astrophysics Data System (ADS)

    Hirose, T.; Mizoguchi, K.

    2008-12-01

    Determination of the energy partitioning during an earthquake is key to understanding the physics of earthquakes (e.g., Kanamori and Rivera, 2006). Observations made on natural faults that have experienced earthquakes suggest that part of the energy dissipates into a volume of rock surrounding the fault though grain crushing processes, forming fault gouge (e.g., Wilson et al., 2005). Thus we performed high-velocity wear experiments using a rotary-shear apparatus, in order to estimate the partitioning of the frictional work into heat and surface energy during frictional sliding at nearly coseismic slip rates. In particular, we attempted to test whether the ratio of the energy partitioning varies as a function of slip rate. The ratio of dissipated energy as heat to the total frictional work was estimated from the difference between measured temperature around the sliding surfaces and calculated temperature by 2D-FEM on the assumption that all frictional work converts into heat. The surface energy was estimated based on the particle size distribution of the wear materials, which was determined by FE-SEM image analysis. The particles size ranged between 0.03 and 10 μm in average diameter. In the experiments, hollow cylindrical specimens of gabbro were slid at slip rates of 0.004 to 0.3 m/s and normal stresses of 0.2 to 5.6 MPa under unconfined and dry conditions. Rock powder (gouge) was continuously produced by abrasive wear of initially bare fault surfaces during sliding. Because the sliding surfaces were not confined in the experiments, the gouge was extruded from the fault surfaces, resulting in shortening of axial length of specimen. In this study, we defined the dimensionless wear rate, given by that an axial shortening rate of the specimen was divided by slip rate. Then, we examined how the wear rate and temperature changed as a function of the rate of frictional work per a unit fault area, Ef, determined by shear stress multiplied by slip rate. Hereafter, Q and

  11. Validation of whole slide imaging for frozen section diagnosis in surgical pathology

    PubMed Central

    Bauer, Thomas W.; Slaw, Renee J.; McKenney, Jesse K.; Patil, Deepa T.

    2015-01-01

    Background: Whole slide imaging (WSI) using high-resolution scanners is gaining acceptance as a platform for consultation as well as for frozen section (FS) evaluation in surgical pathology. We report results of an intra-observer concordance study comparing evaluation of WSI of scanned FS microscope slides with the original interpretation of the same microscope slides after an average lag time of approximately 1-year. Methods: A total of 70 FS cases (148 microscope slides) originally interpreted by 2 pathologists were scanned at ×20 using Aperio CS2 scanner (Leica Biosystems, San Diego, CA, USA). Reports were redacted such that the study pathologists reviewed images using eSlide Manager Healthcare Network application (Leica Biosystems) accompanied by the same clinical information available at the time of original FS evaluation. Discrepancies between the original FS diagnosis and WSI diagnosis were categorized as major (impacted patient care) or minor (no impact on patient care). Results: Lymph nodes, margins for head and neck cancer resections, and arthroplasty specimens to exclude infection, were the most common FS specimens. The average wash-out interval was 380 days (range: 303–466 days). There was one major discrepancy (1.4% of 70 cases) where the original FS was interpreted as severe squamous dysplasia, and the WSI FS diagnosis was mild dysplasia. There were two minor discrepancies; one where the original FS was called focal moderate squamous dysplasia and WSI FS diagnosis was negative for dysplasia. The second case was an endometrial adenocarcinoma that was originally interpreted as Federation of Gynecology and Obstetrics (FIGO) Grade I, while the WSI FS diagnosis was FIGO Grade II. Conclusions: These findings validate and support the use of WSI to provide interpretation of FS in our network of affiliated hospitals and ambulatory surgery centers. PMID:26430537

  12. Terrain analysis of the racetrack basin and the sliding rocks of Death Valley

    USGS Publications Warehouse

    Messina, P.; Stoffer, P.

    2000-01-01

    The Racetrack Playa's unusual surface features known as sliding rocks have been the subject of an ongoing debate and several mapping projects for half a century, although the causative mechanism remains unresolved. Clasts ranging in volume from large pebbles to medium boulders have, unwitnessed, maneuvered around the nearly flat dry lake over considerable distances. The controversy has persisted partly because eyewitness accounts of the phenomenon continue to be lacking, and the earlier mapping missions were limited in method and geographic range. In July 1996, we generated the first complete map of all observed sliding rock trails by submeter differential Global Positioning System (DGPS) mapping technology. The resulting map shows 162 sliding rocks and associated trails to an accuracy of approximately 30 cm. Although anemometer data are not available in the Racetrack wilderness, wind is clearly a catalyst for sliding rock activity; an inferred wind rose was constructed from DGPS trail segment data. When the entire trail network is examined in plan, some patterns emerge, although other (perhaps expected relations) remain elusive: terrain analysis of the surrounding topography demonstrates that the length and morphology of trails are more closely related to where rocks rested at the onset of motion than to any physical attribute of the rocks themselves. Follow-up surveys in May 1998, May 1999, August 1999, and November 1999 revealed little modification of the July, 1996 sliding rock configuration. Only four rocks were repositioned during the El Nino winter of 1997-1998, suggesting that activity may not be restricted to winter storms. (C) 2000 Elsevier Science B.V. All rights reserved.

  13. Grain boundary sliding in aluminum nano-bi-crystals deformed at room temperature.

    PubMed

    Aitken, Zachary H; Jang, Dongchan; Weinberger, Christopher R; Greer, Julia R

    2014-01-15

    Room-temperature uniaxial compressions of 900-nm-diameter aluminum bi-crystals, each containing a high-angle grain boundary with a plane normal inclined at 24° to the loading direction, revealed frictional sliding along the boundary plane to be the dominant deformation mechanism. The top crystallite sheared off as a single unit in the course of compression instead of crystallographic slip and extensive dislocation activity, as would be expected. Compressive stress strain data of deforming nano bicrystals was continuous, in contrast to single crystalline nano structures that show a stochastic stress strain signature, and displayed a peak in stress at the elastic limit of ~ 176 MPa followed by gradual softening and a plateau centered around ~ 125 MPa. An energetics-based physical model, which may explain observed room-temperature grain boundary sliding, in presented, and observations are discussed within the framework of crystalline nano-plasticity and defect microstructure evolution.

  14. MIMO Sliding Mode Control for a Tailless Fighter Aircraft, An Alternative to Reconfigurable Architectures

    NASA Technical Reports Server (NTRS)

    Wells, S. R.; Hess, R. A.

    2002-01-01

    A frequency-domain procedure for the design of sliding mode controllers for multi-input, multi-output (MIMO) systems is presented. The methodology accommodates the effects of parasitic dynamics such as those introduced by unmodeled actuators through the introduction of multiple asymptotic observers and model reference hedging. The design procedure includes a frequency domain approach to specify the sliding manifold, the observer eigenvalues, and the hedge model. The procedure is applied to the development of a flight control system for a linear model of the Innovative Control Effector (ICE) fighter aircraft. The stability and performance robustness of the resulting design is demonstrated through the introduction of significant degradation in the control effector actuators and variation in vehicle dynamics.

  15. Dry sliding wear system response of ferritic and tempered martensitic ductile iron

    NASA Astrophysics Data System (ADS)

    Jha, V. K.; Mozumder, Y. H.; Shama, S.; Behera, R. K.; Pattaniak, A.; P, Sindhoora L.; Mishra, S. C.; Sen, S.

    2015-02-01

    Spheroidal graphite cast iron (SG iron) is the most preferable member of cast iron family due to its strength and toughness along with good tribological properties. SG iron specimens with annealed and martensitic matrix were subjected to dry sliding wear condition and the system response was correlated to matrix microstructure. Respective microstructure was obtained by annealing and quench and tempering heat treatment process for an austenitizing temperature of 1000°C. Specimens were subjected to Ball on plate wear tester under 40N, 50N, 60N load for a sliding distance of 7.54m. Except for quench and tempered specimen at 50N, weight loss was observed in every condition. The wear surface under optical microscope reveals adhesive mechanism for as-cast and annealed specimen whereas delaminated wear track feature was observed for quench and tempered specimen.

  16. Grain boundary sliding in aluminum nano-bi-crystals deformed at room temperature.

    PubMed

    Aitken, Zachary H; Jang, Dongchan; Weinberger, Christopher R; Greer, Julia R

    2014-01-15

    Room-temperature uniaxial compressions of 900-nm-diameter aluminum bi-crystals, each containing a high-angle grain boundary with a plane normal inclined at 24° to the loading direction, revealed frictional sliding along the boundary plane to be the dominant deformation mechanism. The top crystallite sheared off as a single unit in the course of compression instead of crystallographic slip and extensive dislocation activity, as would be expected. Compressive stress strain data of deforming nano bicrystals was continuous, in contrast to single crystalline nano structures that show a stochastic stress strain signature, and displayed a peak in stress at the elastic limit of ~ 176 MPa followed by gradual softening and a plateau centered around ~ 125 MPa. An energetics-based physical model, which may explain observed room-temperature grain boundary sliding, in presented, and observations are discussed within the framework of crystalline nano-plasticity and defect microstructure evolution. PMID:23873787

  17. A Numerical Dynamic Contact Angle Model Applied to Droplets Sliding Down An Incline

    NASA Astrophysics Data System (ADS)

    Afkhami, Shahriar; Bussmann, Markus

    2007-11-01

    A numerical dynamic contact angle model based on a well-known hydrodynamic theory is developed for the imposition of a boundary condition at the contact line. The efficacy of this new model is demonstrated via 3D examples of a viscous droplet sliding down a partially wetting incline. As experimentally observed (Phys. Rev. Lett. 87 (2001), 036102), when the inclination angle increases, the rear of the drop becomes elongated until it develops a ``corner'' which eventually breaks up into smaller droplets, while the leading edge of the drop remains rounded. Using the open source code ``Gerris'' (http://gfs.sf.net), we present the results of droplets sliding on an inclined plane. A similar behaviour (asymmetry between advancing and receding contact lines) is demonstrated. Results are in qualitative agreement with experimental observations. The role of surface inclination on the distribution of the dynamic contact angle along the droplet perimeter is also presented.

  18. Initial rotor position estimation and sliding preventing for elevators with surface-mounted PMSMs

    NASA Astrophysics Data System (ADS)

    Liu, Feng; Shen, Anwen; Tang, Qipeng; Xu, Jinbang

    2016-03-01

    Improved methods of initial rotor position estimation and sliding prevention are presented in this paper for elevators with surface-mounted permanent magnet synchronous machines (SPMSMs). In contrast to most of the existing literature, in this paper, estimation errors caused by stator resistance and dead time are analysed in detail. The improved estimation method can reduce the errors greatly without dead-time compensations and knowledge of motor parameters. Besides, an observer-based feedforward compensation of load torque is introduced to elevator applications to prevent sliding during the starting process. Since the torque observer is widely used in other motor applications, we focus on the impact caused by the change in inertia. Finally, a series of experiments are performed on a testing system with two 13.4 kW SPMSMs and drivers to illustrate the effectiveness and improvement of the method.

  19. A novel guidance law using fast terminal sliding mode control with impact angle constraints.

    PubMed

    Sun, Lianghua; Wang, Weihong; Yi, Ran; Xiong, Shaofeng

    2016-09-01

    This paper is concerned with the question of, for a missile interception with impact angle constraints, how to design a guidance law. Firstly, missile interception with impact angle constraints is modeled; secondly, a novel guidance law using fast terminal sliding mode control based on extended state observer is proposed to optimize the trajectory and time of interception; finally, for stationary targets, constant velocity targets and maneuvering targets, the guidance law and the stability of the closed loop system is analyzed and the stability of the closed loop system is analyzed, respectively. Simulation results show that when missile and target are on a collision course, the novel guidance law using fast terminal sliding mode control with extended state observer has more optimized trajectory and effectively reduces the time of interception which has a great significance in modern warfare. PMID:27238736

  20. A novel guidance law using fast terminal sliding mode control with impact angle constraints.

    PubMed

    Sun, Lianghua; Wang, Weihong; Yi, Ran; Xiong, Shaofeng

    2016-09-01

    This paper is concerned with the question of, for a missile interception with impact angle constraints, how to design a guidance law. Firstly, missile interception with impact angle constraints is modeled; secondly, a novel guidance law using fast terminal sliding mode control based on extended state observer is proposed to optimize the trajectory and time of interception; finally, for stationary targets, constant velocity targets and maneuvering targets, the guidance law and the stability of the closed loop system is analyzed and the stability of the closed loop system is analyzed, respectively. Simulation results show that when missile and target are on a collision course, the novel guidance law using fast terminal sliding mode control with extended state observer has more optimized trajectory and effectively reduces the time of interception which has a great significance in modern warfare.

  1. Development and Validation of a Histological Method to Measure Microvessel Density in Whole-Slide Images of Cancer Tissue.

    PubMed

    Marien, Koen M; Croons, Valerie; Waumans, Yannick; Sluydts, Ellen; De Schepper, Stefanie; Andries, Luc; Waelput, Wim; Fransen, Erik; Vermeulen, Peter B; Kockx, Mark M; De Meyer, Guido R Y

    2016-01-01

    Despite all efforts made to develop predictive biomarkers for antiangiogenic therapies, no unambiguous markers have been identified so far. This is due to among others the lack of standardized tests. This study presents an improved microvessel density quantification method in tumor tissue based on stereological principles and using whole-slide images. Vessels in tissue sections of different cancer types were stained for CD31 by an automated and validated immunohistochemical staining method. The stained slides were digitized with a digital slide scanner. Systematic, uniform, random sampling of the regions of interest on the whole-slide images was performed semi-automatically with the previously published applications AutoTag and AutoSnap. Subsequently, an unbiased counting grid was combined with the images generated with these scripts. Up to six independent observers counted microvessels in up to four cancer types: colorectal carcinoma, glioblastoma multiforme, ovarian carcinoma and renal cell carcinoma. At first, inter-observer variability was found to be unacceptable. However, after a series of consensus training sessions and interim statistical analysis, counting rules were modified and inter-observer concordance improved considerably. Every CD31-positive object was counted, with exclusion of suspected CD31-positive monocytes, macrophages and tumor cells. Furthermore, if interconnected, stained objects were considered a single vessel. Ten regions of interest were sufficient for accurate microvessel density measurements. Intra-observer and inter-observer variability were low (intraclass correlation coefficient > 0.7) if the observers were adequately trained. PMID:27583442

  2. Development and Validation of a Histological Method to Measure Microvessel Density in Whole-Slide Images of Cancer Tissue

    PubMed Central

    Croons, Valerie; Waumans, Yannick; Sluydts, Ellen; De Schepper, Stefanie; Andries, Luc; Waelput, Wim; Fransen, Erik; Vermeulen, Peter B.; Kockx, Mark M.; De Meyer, Guido R. Y.

    2016-01-01

    Despite all efforts made to develop predictive biomarkers for antiangiogenic therapies, no unambiguous markers have been identified so far. This is due to among others the lack of standardized tests. This study presents an improved microvessel density quantification method in tumor tissue based on stereological principles and using whole-slide images. Vessels in tissue sections of different cancer types were stained for CD31 by an automated and validated immunohistochemical staining method. The stained slides were digitized with a digital slide scanner. Systematic, uniform, random sampling of the regions of interest on the whole-slide images was performed semi-automatically with the previously published applications AutoTag and AutoSnap. Subsequently, an unbiased counting grid was combined with the images generated with these scripts. Up to six independent observers counted microvessels in up to four cancer types: colorectal carcinoma, glioblastoma multiforme, ovarian carcinoma and renal cell carcinoma. At first, inter-observer variability was found to be unacceptable. However, after a series of consensus training sessions and interim statistical analysis, counting rules were modified and inter-observer concordance improved considerably. Every CD31-positive object was counted, with exclusion of suspected CD31-positive monocytes, macrophages and tumor cells. Furthermore, if interconnected, stained objects were considered a single vessel. Ten regions of interest were sufficient for accurate microvessel density measurements. Intra-observer and inter-observer variability were low (intraclass correlation coefficient > 0.7) if the observers were adequately trained. PMID:27583442

  3. Nontrivial scaling laws for a block sliding down a rough plane

    NASA Astrophysics Data System (ADS)

    Brito, V. P.; Gomes, M. A. F.

    1996-04-01

    The measured length distributions of slidings of solid cylinders of aluminum, brass, teflon, and polyvinyl chloride on an incline obey nontrivial scaling laws. No significant dependence of the scaling exponent on material is observed and the data obtained are in agreement with the Gutenberg-Richter law for the distribution of earthquakes and with numerical simulations exhibiting self-organized criticality made by Chen, Bak, and Obukhov [Phys. Rev. A 43, 625-630 (1991)].

  4. 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...

  5. Simultaneous Modeling of Transient Creep and Grain Boundary Sliding

    NASA Astrophysics Data System (ADS)

    Cooper, R. F.; Sundberg, M.

    2009-12-01

    Grain boundary sliding (GBS) has been identified as an important contributor to the plastic deformation of polycrystalline solids. This phenomenon, whether accommodated by grain boundary diffusion or dislocation slip, has implications for rheological behavior and microstructural evolution during creep. Because GBS is not an independent deformation mechanism, but rather acts in kinetic series with some other (typically) rate-limiting process, direct investigation of the precise sliding mechanism(s) is difficult during conventional large-strain creep testing. Direct observations of grain boundary sliding can be obtained, however, by: (1) observing the mechanical response of a polycrystalline solid to an oscillating load as a function of frequency using the internal friction technique, and (2) studying the short duration transient response of a polycrystalline solid to a step-function change in stress. To this end, we have conducted an experimental study of low-frequency (10-2.2510-0.5 Hz), the attenuation spectra reveal the onset of an apparent Debye peak in the attenuation spectra, likely due to elastically-accommodated GBS (GBS being rate-limiting). Previous experimental studies have demonstrated that the Andrade viscoelastic model can accurately predict both the transient creep response and

  6. Muscle Synergies of Untrained Subjects during 6 min Maximal Rowing on Slides and Fixed Ergometer.

    PubMed

    Shaharudin, Shazlin; Zanotto, Damiano; Agrawal, Sunil

    2014-12-01

    The slides ergometer (SE) was an improvisation from fixed ergometer (FE) to bridge the gap of mechanics between ergometer rowing and on-water rowing. The specific mechanical constraints of these two types of ergometers may affect the pattern of muscle recruitment, coordination and adaptation. The main purpose of this study was to evaluate the muscle synergy during 6 minutes maximal rowing on slides (SE) and fixed ergometers (FE). The laterality of muscle synergy was also examined. Surface electromyography activity, power output, heart rate, stroke length and stroke rate were analyzed from nine physically active subjects to assess the rowing performance. Physically active subjects, who were not specifically trained in rowing, were chosen to exclude the training effect on muscle synergy. Principal component analysis (PCA) with varimax rotation was applied to extract muscle synergy. Three muscle synergies were sufficient to explain the majority of variance in SE (94.4 ± 2.2 %) and FE (92.8 ± 1.7 %). Subjects covered more rowing distance, exerted greater power output and attained higher maximal heart rate during rowing on SE than on FE. The results proved the flexibility of muscle synergy to adapt to the mechanical constraints. Rowing on SE emphasized on bi-articular muscles contrary to rowing on FE which relied on cumulative effect of trunk and upper limb muscles during propulsive phase. Key pointsThree muscle synergies were extracted during maximal rowing on both fixed and slides ergometerUntrained subjects emphasized leg muscles while rowing on SEUntrained subjects focused on back muscles during FE rowing. PMID:25435771

  7. Adaptive capacity of the Adjusted Clinical Groups Case-Mix System to the cost of primary healthcare in Catalonia (Spain): a observational study

    PubMed Central

    Velasco-Velasco, Soledad; Navarro-Artieda, Ruth; Prados-Torres, Alexandra; Bolibar-Ribas, Buenaventura; Violan-Fors, Concepción

    2012-01-01

    Objectives To describe the adaptive capacity of the Adjusted Clinical Groups (ACG) system to the cost of care in primary healthcare centres in Catalonia (Spain). Design Retrospective study (multicentres) conducted using computerised medical records. Setting 13 primary care teams in 2008 were included. Participants All patients registered in the study centres who required care between 1 January and 31 December 2008 were finally studied. Patients not registered in the study centres during the study period were excluded. Outcome measures Demographic (age and sex), dependent (cost of care) and case-mix variables were studied. The cost model for each patient was established by differentiating the fixed and variable costs. To evaluate the adaptive capacity of the ACG system, Pearson's coefficient of variation and the percentage of outliers were calculated. To evaluate the explanatory power of the ACG system, the authors used the coefficient of determination (R2). Results The number of patients studied was 227 235 (frequency: 5.9 visits per person per year), with a mean of 4.5 (3.2) episodes and 8.1 (8.2) visits per patient per year. The mean total cost was €654.2. The explanatory power of the ACG system was 36.9% for costs (56.5% without outliers). 10 ACG categories accounted for 60.1% of all cases and 19 for 80.9%. 5 categories represented 71% of poor performance (N=78 887, 34.7%), particularly category 0300-Acute Minor, Age 6+ (N=26 909, 11.8%), which had a coefficient of variation =139% and 6.6% of outliers. Conclusions The ACG system is an appropriate manner of classifying patients in routine clinical practice in primary healthcare centres in Catalonia, although improvements to the adaptive capacity through disaggregation of some categories according to age groups and, especially, the number of acute episodes in paediatric patients would be necessary to reduce intra-group variation. PMID:22734115

  8. Sliding Wear Behavior of TiC-Reinforced Cu-4 wt.% Ni Matrix Composites

    NASA Astrophysics Data System (ADS)

    Jha, Pushkar; Gautam, R. K.; Tyagi, Rajnesh; Kumar, Devendra

    2016-08-01

    The present investigation explores the effect of TiC content on the sliding wear properties of Cu-4 wt.% Ni matrix composites. Cu-4 wt.% Ni - x wt.% TiC (x = 0, 2, 4 and 8 wt.%) metal matrix composites were developed by powder metallurgy route. Their friction and wear was studied under dry sliding at different loads of 5, 7.5 and 10 N and constant sliding speed of 2 m/s using a pin-on-disk machine. The metallographic observations showed an almost uniform distribution of TiC particles in the matrix. Hardness of the composites increased with increasing TiC content (up to 4 wt.%). Friction and wear results of TiC-reinforced composites show better wear resistance than unreinforced matrix alloy. However, the optimum wear resistance was observed for 4 wt.% TiC-reinforced composites. Worn surfaces of specimens indicated the abrasion as the primary mechanism of wear in all the materials investigated in the study. The observed behavior has been explained on the basis of (1) the hardness which results in a decrease in real area of contact in composites containing TiC particles and (2) the formation of a transfer layer of wear debris on the surface of the composites which protects underlying substrate by inhibiting metal-metal contact.

  9. Sliding Wear Behavior of TiC-Reinforced Cu-4 wt.% Ni Matrix Composites

    NASA Astrophysics Data System (ADS)

    Jha, Pushkar; Gautam, R. K.; Tyagi, Rajnesh; Kumar, Devendra

    2016-10-01

    The present investigation explores the effect of TiC content on the sliding wear properties of Cu-4 wt.% Ni matrix composites. Cu-4 wt.% Ni - x wt.% TiC ( x = 0, 2, 4 and 8 wt.%) metal matrix composites were developed by powder metallurgy route. Their friction and wear was studied under dry sliding at different loads of 5, 7.5 and 10 N and constant sliding speed of 2 m/s using a pin-on-disk machine. The metallographic observations showed an almost uniform distribution of TiC particles in the matrix. Hardness of the composites increased with increasing TiC content (up to 4 wt.%). Friction and wear results of TiC-reinforced composites show better wear resistance than unreinforced matrix alloy. However, the optimum wear resistance was observed for 4 wt.% TiC-reinforced composites. Worn surfaces of specimens indicated the abrasion as the primary mechanism of wear in all the materials investigated in the study. The observed behavior has been explained on the basis of (1) the hardness which results in a decrease in real area of contact in composites containing TiC particles and (2) the formation of a transfer layer of wear debris on the surface of the composites which protects underlying substrate by inhibiting metal-metal contact.

  10. The Evolution of Interfacial Sliding Stresses During Cyclic Push-in Testing of C- and BN-Coated Hi-Nicalon Fiber-Reinforced CMCs

    NASA Technical Reports Server (NTRS)

    Eldridge, J. I.; Bansal, N. P.; Bhatt, R. T.

    1998-01-01

    Interfacial debond cracks and fiber/matrix sliding stresses in ceramic matrix composites (CMCs) can evolve under cyclic fatigue conditions as well as with changes in the environment, strongly affecting the crack growth behavior, and therefore, the useful service lifetime of the composite. In this study, room temperature cyclic fiber push-in testing was applied to monitor the evolution of frictional sliding stresses and fiber sliding distances with continued cycling in both C- and BN-coated Hi-Nicalon SiC fiber-reinforced CMCs. A SiC matrix composite reinforced with C-coated Hi-Nical on fibers as well as barium strontium aluminosilicate (BSAS) matrix composites reinforced with BN-coated (four different deposition processes compared) Hi-Nicalon fibers were examined. For failure at a C interface, test results indicated progressive increases in fiber sliding distances during cycling in room air but not in nitrogen. These results suggest the presence of moisture will promote crack growth when interfacial failure occurs at a C interface. While short-term testing environmental effects were not apparent for failure at the BN interfaces, long-term exposure of partially debonded BN-coated fibers to humid air resulted in large increases in fiber sliding distances and decreases in interfacial sliding stresses for all the BN coatings, presumably due to moisture attack. A wide variation was observed in debond and frictional sliding stresses among the different BN coatings.

  11. Single molecule study of a processivity clamp sliding on DNA

    SciTech Connect

    Laurence, T A; Kwon, Y; Johnson, A; Hollars, C; O?Donnell, M; Camarero, J A; Barsky, D

    2007-07-05

    Using solution based single molecule spectroscopy, we study the motion of the polIII {beta}-subunit DNA sliding clamp ('{beta}-clamp') on DNA. Present in all cellular (and some viral) forms of life, DNA sliding clamps attach to polymerases and allow rapid, processive replication of DNA. In the absence of other proteins, the DNA sliding clamps are thought to 'freely slide' along the DNA; however, the abundance of positively charged residues along the inner surface may create favorable electrostatic contact with the highly negatively charged DNA. We have performed single-molecule measurements on a fluorescently labeled {beta}-clamp loaded onto freely diffusing plasmids annealed with fluorescently labeled primers of up to 90 bases. We find that the diffusion constant for 1D diffusion of the {beta}-clamp on DNA satisfies D {le} 10{sup -14} cm{sup 2}/s, much slower than the frictionless limit of D = 10{sup -10} cm{sup 2}/s. We find that the {beta} clamp remains at the 3-foot end in the presence of E. coli single-stranded binding protein (SSB), which would allow for a sliding clamp to wait for binding of the DNA polymerase. Replacement of SSB with Human RP-A eliminates this interaction; free movement of sliding clamp and poor binding of clamp loader to the junction allows sliding clamp to accumulate on DNA. This result implies that the clamp not only acts as a tether, but also a placeholder.

  12. Humboldt slide - A large shear-dominated retrogressive slope failure

    USGS Publications Warehouse

    Gardner, J.V.; Prior, D.B.; Field, M.E.

    1999-01-01

    Humboldt Slide is a large, complex slide zone located on the northern California continental margin. Its three-dimensional architecture has been imaged by a combination of multibeam bathymetry, Huntec Deep-Tow seismic profiling, and sidescan sonar. The slide is interpreted to be Late Pleistocene to early Holocene in age and was caused by a combination of factors. The area of the slide is a local depocenter with high accumulation rates of organic-rich sediment; there has been local steepening of slopes by tectonic uplifts; and the entire area is one of high seismicity. Overall, the failure occurred by retrogressive, shear-dominated, minimum movement apparently as a sequence of events. Failure initially occurred by subsidence extension at the middle of the feature, followed by upslope retrogressive failure and downslope compression, and finally by translational sliding at the top of the slide. Degassing, as evidenced by abundant pockmarks, may have inhibited downslope translation. The slide may still be active, as suggested by offsets in Holocene hemipelagic sediment draped over some of the shear surfaces. Crown cracks occur above the present head of the failure and may represent the next generation of failure.

  13. Estimation of lung lobar sliding using image registration

    NASA Astrophysics Data System (ADS)

    Amelon, Ryan; Cao, Kunlin; Reinhardt, Joseph M.; Christensen, Gary E.; Raghavan, Madhavan

    2012-03-01

    MOTIVATION: The lobes of the lungs slide relative to each other during breathing. Quantifying lobar sliding can aid in better understanding lung function, better modeling of lung dynamics, and a better understanding of the limits of image registration performance near fissures. We have developed a method to estimate lobar sliding in the lung from image registration of CT scans. METHODS: Six human lungs were analyzed using CT scans spanning functional residual capacity (FRC) to total lung capacity (TLC). The lung lobes were segmented and registered on a lobe-by-lobe basis. The displacement fields from the independent lobe registrations were then combined into a single image. This technique allows for displacement discontinuity at lobar boundaries. The displacement field was then analyzed as a continuum by forming finite elements from the voxel grid of the FRC image. Elements at a discontinuity will appear to have undergone significantly elevated 'shear stretch' compared to those within the parenchyma. Shear stretch is shown to be a good measure of sliding magnitude in this context. RESULTS: The sliding map clearly delineated the fissures of the lung. The fissure between the right upper and right lower lobes showed the greatest sliding in all subjects while the fissure between the right upper and right middle lobe showed the least sliding.

  14. Second-order sliding mode control with experimental application.

    PubMed

    Eker, Ilyas

    2010-07-01

    In this article, a second-order sliding mode control (2-SMC) is proposed for second-order uncertain plants using equivalent control approach to improve the performance of control systems. A Proportional + Integral + Derivative (PID) sliding surface is used for the sliding mode. The sliding mode control law is derived using direct Lyapunov stability approach and asymptotic stability is proved theoretically. The performance of the closed-loop system is analysed through an experimental application to an electromechanical plant to show the feasibility and effectiveness of the proposed second-order sliding mode control and factors involved in the design. The second-order plant parameters are experimentally determined using input-output measured data. The results of the experimental application are presented to make a quantitative comparison with the traditional (first-order) sliding mode control (SMC) and PID control. It is demonstrated that the proposed 2-SMC system improves the performance of the closed-loop system with better tracking specifications in the case of external disturbances, better behavior of the output and faster convergence of the sliding surface while maintaining the stability.

  15. Comparing whole slide digital images versus traditional glass slides in the detection of common microscopic features seen in dermatitis

    PubMed Central

    Vyas, Nikki S.; Markow, Michael; Prieto-Granada, Carlos; Gaudi, Sudeep; Turner, Leslie; Rodriguez-Waitkus, Paul; Messina, Jane L.; Jukic, Drazen M.

    2016-01-01

    Background: The quality and limitations of digital slides are not fully known. We aimed to estimate intrapathologist discrepancy in detecting specific microscopic features on glass slides and digital slides created by scanning at ×20. Methods: Hematoxylin and eosin and periodic acid–Schiff glass slides were digitized using the Mirax Scan (Carl Zeiss Inc., Germany). Six pathologists assessed 50–71 digital slides. We recorded objective magnification, total time, and detection of the following: Mast cells; eosinophils; plasma cells; pigmented macrophages; melanin in the epidermis; fungal bodies; neutrophils; civatte bodies; parakeratosis; and sebocytes. This process was repeated using the corresponding glass slides after 3 weeks. The diagnosis was not required. Results: The mean time to assess digital slides was 176.77 s and 137.61 s for glass slides (P < 0.001, 99% confidence interval [CI]). The mean objective magnification used to detect features using digital slides was 18.28 and 14.07 for glass slides (P < 0.001, 99.99% CI). Parakeratosis, civatte bodies, pigmented macrophages, melanin in the epidermis, mast cells, eosinophils, plasma cells, and neutrophils, were identified at lower objectives on glass slides (P = 0.023–0.001, 95% CI). Average intraobserver concordance ranged from κ = 0.30 to κ = 0.78. Features with poor to fair average concordance were: Melanin in the epidermis (κ = 0.15–0.58); plasma cells (κ = 0.15–0.49); and neutrophils (κ = 0.12–0.48). Features with moderate average intrapathologist concordance were: parakeratosis (κ = 0.21–0.61); civatte bodies (κ = 0.21–0.71); pigment-laden macrophages (κ = 0.34–0.66); mast cells (κ = 0.29–0.78); and eosinophils (κ = 0.31–0.79). The average intrapathologist concordance was good for sebocytes (κ = 0.51–1.00) and fungal bodies (κ = 0.47–0.76). Conclusions: Telepathology using digital slides scanned at ×20 is sufficient for detection of histopathologic features routinely

  16. SurfaceSlide: A Multitouch Digital Pathology Platform

    PubMed Central

    Wang, Yinhai; Williamson, Kate E.; Kelly, Paul J.; James, Jacqueline A.; Hamilton, Peter W.

    2012-01-01

    Background Digital pathology provides a digital environment for the management and interpretation of pathological images and associated data. It is becoming increasing popular to use modern computer based tools and applications in pathological education, tissue based research and clinical diagnosis. Uptake of this new technology is stymied by its single user orientation and its prerequisite and cumbersome combination of mouse and keyboard for navigation and annotation. Methodology In this study we developed SurfaceSlide, a dedicated viewing platform which enables the navigation and annotation of gigapixel digitised pathological images using fingertip touch. SurfaceSlide was developed using the Microsoft Surface, a 30 inch multitouch tabletop computing platform. SurfaceSlide users can perform direct panning and zooming operations on digitised slide images. These images are downloaded onto the Microsoft Surface platform from a remote server on-demand. Users can also draw annotations and key in texts using an on-screen virtual keyboard. We also developed a smart caching protocol which caches the surrounding regions of a field of view in multi-resolutions thus providing a smooth and vivid user experience and reducing the delay for image downloading from the internet. We compared the usability of SurfaceSlide against Aperio ImageScope and PathXL online viewer. Conclusion SurfaceSlide is intuitive, fast and easy to use. SurfaceSlide represents the most direct, effective and intimate human–digital slide interaction experience. It is expected that SurfaceSlide will significantly enhance digital pathology tools and applications in education and clinical practice. PMID:22292040

  17. Geomorphology, stability and mobility of the Currituck slide

    USGS Publications Warehouse

    Locat, J.; Lee, H.; ten Brink, U.S.; Twichell, D.; Geist, E.; Sansoucy, M.

    2009-01-01

    Over the last 100,000??years, the U.S. Atlantic continental margin has experienced various types of mass movements some of which are believed to have taken place at times of low sea level. At one of these times of low sea level a significant trigger caused a major submarine mass movement off the coast of Virginia: the Currituck slide which is believed to have taken place between 24 and 50??ka ago. This slide removed a total volume of about 165??km3 from this section of the continental slope. The departure zone still shows a very clean surface that dips at 4?? and is only covered by a thin veneer of postglacial sediment. Multibeam bathymetric and seismic survey data suggest that this slide took place along three failures surfaces. The morphology of the source area suggests that the sediments were already at least normally consolidated at the time of failure. The slide debris covers an area as much as 55??km wide that extends 180??km from the estimated toe of the original slope. The back analysis of slide initiation indicates that very high pore pressure, a strong earthquake, or both had to be generated to trigger slides on such a low failure plane angle. The shape of the failure plane, the fact that the surface is almost clear of any debris, and the mobility analysis, all support the argument that the slides took place nearly simultaneously. Potential causes for the generation of high pore pressures could be seepage forces from coastal aquifers, delta construction and related pore pressure generation due to the local sediment loading, gas hydrates, and earthquakes. This slide, and its origin, is a spectacular example of the potential threat that submarine mass movements can pose to the US Atlantic coast and underline the need to further assess the potential for the generation of such large slides, like the Grand Banks 1927 landslide of similar volume. ?? 2008 Elsevier B.V.

  18. Introducing Slide Sets for the Introductory Astronomy Instructor

    NASA Astrophysics Data System (ADS)

    Meinke, Bonnie K.; Schneider, Nicholas; Brain, David; Schultz, Gregory; Buxner, Sanlyn; Smith, Denise

    2014-11-01

    The NASA Science Mission Directorate (SMD) Science Education and Public Outreach (E/PO) community and Forums work together to bring the cutting-edge discoveries of NASA Astrophysics and Planetary Science missions to the introductory astronomy college classroom. These mission- and grant-based E/PO programs are uniquely poised to foster collaboration between scientists with content expertise and educators with pedagogy expertise. We present two new opportunities for college instructors to bring the latest NASA discoveries in Space Science into their classrooms.In an effort to keep the astronomy classroom apprised of the fast moving field of planetary science, the Division of Planetary Sciences (DPS) has developed “DPS Discoveries”, which are short, topical presentations that can be incorporated into college lectures. The slide sets are targeted at the Introductory Astronomy undergraduate level. Each slide set consists of three slides that cover a description of the discovery, a discussion of the underlying science, and a presentation of the big picture implications of the discovery, with a fourth slide that includes links to associated press releases, images, and primary sources. Topics span all subdisciplines of planetary science, and sets are available in Farsi and Spanish. The NASA SMD Planetary Science Forum has recently partnered with the DPS to continue producing the Discovery slides and connect them to NASA mission science. http://dps.aas.org/education/dpsdisc Similarly, the NASA SMD Astrophysics Forum is coordinating the development of a series of slide sets to help Astronomy 101 instructors incorporate new discoveries in their classrooms. The “Astro 101 slide sets” are presentations 5-7 slides in length on a new development or discovery from a NASA Astrophysics mission relevant to topics in introductory astronomy courses. We intend for these slide sets to help Astronomy 101 instructors include new developments (not yet in their textbooks) into the

  19. Robust sliding mode control applied to double Inverted pendulum system

    SciTech Connect

    Mahjoub, Sonia; Derbel, Nabil; Mnif, Faical

    2009-03-05

    A three hierarchical sliding mode control is presented for a class of an underactuated system which can overcome the mismatched perturbations. The considered underactuated system is a double inverted pendulum (DIP), can be modeled by three subsystems. Such structure allows the construction of several designs of hierarchies for the controller. For all hierarchical designs, the asymptotic stability of every layer sliding mode surface and the sliding mode surface of subsystems are proved theoretically by Barbalat's lemma. Simulation results show the validity of these methods.

  20. Robust sliding mode control applied to double Inverted pendulum system

    NASA Astrophysics Data System (ADS)

    Mahjoub, Sonia; Mnif, Faiçal; Derbel, Nabil

    2009-03-01

    A three hierarchical sliding mode control is presented for a class of an underactuated system which can overcome the mismatched perturbations. The considered underactuated system is a double inverted pendulum (DIP), can be modeled by three subsystems. Such structure allows the construction of several designs of hierarchies for the controller. For all hierarchical designs, the asymptotic stability of every layer sliding mode surface and the sliding mode surface of subsystems are proved theoretically by Barbalat's lemma. Simulation results show the validity of these methods.

  1. Fireplace adapters

    SciTech Connect

    Hunt, R.L.

    1983-12-27

    An adapter is disclosed for use with a fireplace. The stove pipe of a stove standing in a room to be heated may be connected to the flue of the chimney so that products of combustion from the stove may be safely exhausted through the flue and outwardly of the chimney. The adapter may be easily installed within the fireplace by removing the damper plate and fitting the adapter to the damper frame. Each of a pair of bolts has a portion which hooks over a portion of the damper frame and a threaded end depending from the hook portion and extending through a hole in the adapter. Nuts are threaded on the bolts and are adapted to force the adapter into a tight fit with the adapter frame.

  2. Evidence for cohesin sliding along budding yeast chromosomes

    PubMed Central

    Ocampo-Hafalla, Maria; Muñoz, Sofía; Samora, Catarina P.; Uhlmann, Frank

    2016-01-01

    The ring-shaped cohesin complex is thought to topologically hold sister chromatids together from their synthesis in S phase until chromosome segregation in mitosis. How cohesin stably binds to chromosomes for extended periods, without impeding other chromosomal processes that also require access to the DNA, is poorly understood. Budding yeast cohesin is loaded onto DNA by the Scc2–Scc4 cohesin loader at centromeres and promoters of active genes, from where cohesin translocates to more permanent places of residence at transcription termination sites. Here we show that, at the GAL2 and MET17 loci, pre-existing cohesin is pushed downstream along the DNA in response to transcriptional gene activation, apparently without need for intermittent dissociation or reloading. We observe translocation intermediates and find that the distribution of most chromosomal cohesin is shaped by transcription. Our observations support a model in which cohesin is able to slide laterally along chromosomes while maintaining topological contact with DNA. In this way, stable cohesin binding to DNA and enduring sister chromatid cohesion become compatible with simultaneous underlying chromosomal activities, including but maybe not limited to transcription. PMID:27278645

  3. Basal sliding in ice streams as seen through the lens of rock mechanics: an experimental study of ice-on-rock friction

    NASA Astrophysics Data System (ADS)

    McCarthy, C.; Savage, H. M.; Nettles, M.

    2015-12-01

    An understanding of the controls on ice stream flow is critical for improved predictions of sea level rise and glacier response to climate change. Basal sliding is one aspect of ice stream motion that has received relatively little attention. Although it is difficult and costly to measure direct motion at the base of a glacier, laboratory experiments can be used to recreate the physics of ice sliding over bedrock. Using a new, custom-built, servo-controlled biaxial loading apparatus, we are measuring the friction of polycrystalline ice samples sliding on rock in a double direct shear configuration. Temperature is maintained with an insulated cryostat that uses liquid cooling blocks and a programmable circulating bath. We will share results from a series of velocity stepping and slide-hold-slide experiments designed to measure key properties of rate- and state-dependent frictional behavior. The experimental conditions for the study are as follows: temperatures ranging from -20ºC to the pressure melting point; normal stresses of 20 - 200 kPa, velocities from 10-6 to 10-3 m s-1; and ambient pressure. Ice sample microstructure (grain size, porosity, purity) and surface roughness are carefully controlled and characterized before and after experiments to identify microstructural sources for macroscopic behavior. Careful monitoring of temperature at the sliding interface will elucidate the role of frictional heating/melting on both sliding behavior and microstructure evolution. By measuring rate-state friction parameters, we will explore the transition between stable sliding and stick-slip motion of glaciers and ice streams. These results can be directly compared to the differing sliding styles observed for ice streams feeding into the Ross Ice Shelf to infer characteristics of the bed interface and the bulk glacier. The values obtained from this study will provide better constraints for next generation modeling of glacier and ice-stream response to external forcing.

  4. Soft hydrated sliding interfaces as complex fluids.

    PubMed

    Kim, Jiho; Dunn, Alison C

    2016-08-21

    Hydrogel surfaces are biomimics for sensing and mobility systems in the body such as the eyes and large joints due to their important characteristics of flexibility, permeability, and integrated aqueous component. Recent studies have shown polymer concentration gradients resulting in a less dense region in the top micrometers of the surface. Under shear, this gradient is hypothesized to drive lubrication behavior due to its rheological similarity to a semi-dilute polymer solution. In this work we map 3 distinct lubricating regimes between a polyacrylamide surface and an aluminum annulus using stepped-velocity tribo-rheometry over 5 decades of sliding speed in increasing and decreasing steps. These regimes, characterized by weakly or strongly time-dependent response and thixotropy-like hysteresis, provide the skeleton of a lubrication curve for hydrogel-against-hard material interfaces and support hypotheses of polymer mechanics-driven lubrication. Tribo-rheometry is particularly suited to uncover the lubrication mechanisms of complex interfaces such as are formed with hydrated hydrogel surfaces and biological surfaces. PMID:27425448

  5. Sliding Motility, Biofilm Formation, and Glycopeptidolipid Production in Mycobacterium colombiense Strains

    PubMed Central

    Maya-Hoyos, Milena; Leguizamón, John; Mariño-Ramírez, Leonardo; Soto, Carlos Y.

    2015-01-01

    Mycobacterium colombiense is a novel member of the Mycobacterium avium complex, which produces respiratory and disseminated infections in immunosuppressed patients. Currently, the morphological and genetic bases underlying the phenotypic features of M. colombiense strains remain unknown. In the present study, we demonstrated that M. colombiense strains displaying smooth morphology show increased biofilm formation on hydrophobic surfaces and sliding on motility plates. Thin-layer chromatography experiments showed that M. colombiense strains displaying smooth colonies produce large amounts of glycolipids with a chromatographic behaviour similar to that of the glycopeptidolipids (GPLs) of M. avium. Conversely, we observed a natural rough variant of M. colombiense (57B strain) lacking pigmentation and exhibiting impaired sliding, biofilm formation, and GPL production. Bioinformatics analyses revealed a gene cluster that is likely involved in GPL biosynthesis in M. colombiense CECT 3035. RT-qPCR experiments showed that motile culture conditions activate the transcription of genes possibly involved in key enzymatic activities of GPL biosynthesis. PMID:26180799

  6. Mechanisms of antiwear tribofilm growth revealed in situ by single-asperity sliding contacts

    NASA Astrophysics Data System (ADS)

    Gosvami, N. N.; Bares, J. A.; Mangolini, F.; Konicek, A. R.; Yablon, D. G.; Carpick, R. W.

    2015-04-01

    Zinc dialkyldithiophosphates (ZDDPs) form antiwear tribofilms at sliding interfaces and are widely used as additives in automotive lubricants. The mechanisms governing the tribofilm growth are not well understood, which limits the development of replacements that offer better performance and are less likely to degrade automobile catalytic converters over time. Using atomic force microscopy in ZDDP-containing lubricant base stock at elevated temperatures, we monitored the growth and properties of the tribofilms in situ in well-defined single-asperity sliding nanocontacts. Surface-based nucleation, growth, and thickness saturation of patchy tribofilms were observed. The growth rate increased exponentially with either applied compressive stress or temperature, consistent with a thermally activated, stress-assisted reaction rate model. Although some models rely on the presence of iron to catalyze tribofilm growth, the films grew regardless of the presence of iron on either the tip or substrate, highlighting the critical role of stress and thermal activation.

  7. Purified Kinesin Promotes Vesicle Motility and Induces Active Sliding Between Microtubules In vitro

    NASA Astrophysics Data System (ADS)

    Urrutia, Raul; McNiven, Mark A.; Albanesi, Joseph P.; Murphy, Douglas B.; Kachar, Bechara

    1991-08-01

    We examined the ability of kinesin to support the movement of adrenal medullary chromaffin granules on microtubules in a defined in vitro system. We found that kinesin and ATP are all that is required to support efficient (33% vesicle motility) and rapid (0.4-0.6 μ m/s) translocation of secretory granule membranes on microtubules in the presence of a low-salt motility buffer. Kinesin also induced the formation of microtubule asters in this buffer, with the plus ends of microtubules located at the center of each aster. This observation indicates that kinesin is capable of promoting active sliding between microtubules toward their respective plus ends, a movement analogous to that of anaphase b in the mitotic spindle. The fact that vesicle translocation, microtubule sliding, and microtubule-dependent kinesin ATPase activities are all enhanced in low-salt buffer establishes a functional parallel between this translocator and other motility ATPases, myosin, and dynein.

  8. Tribology. Mechanisms of antiwear tribofilm growth revealed in situ by single-asperity sliding contacts.

    PubMed

    Gosvami, N N; Bares, J A; Mangolini, F; Konicek, A R; Yablon, D G; Carpick, R W

    2015-04-01

    Zinc dialkyldithiophosphates (ZDDPs) form antiwear tribofilms at sliding interfaces and are widely used as additives in automotive lubricants. The mechanisms governing the tribofilm growth are not well understood, which limits the development of replacements that offer better performance and are less likely to degrade automobile catalytic converters over time. Using atomic force microscopy in ZDDP-containing lubricant base stock at elevated temperatures, we monitored the growth and properties of the tribofilms in situ in well-defined single-asperity sliding nanocontacts. Surface-based nucleation, growth, and thickness saturation of patchy tribofilms were observed. The growth rate increased exponentially with either applied compressive stress or temperature, consistent with a thermally activated, stress-assisted reaction rate model. Although some models rely on the presence of iron to catalyze tribofilm growth, the films grew regardless of the presence of iron on either the tip or substrate, highlighting the critical role of stress and thermal activation.

  9. Space-based line-of-sight tracking control of GEO target using nonsingular terminal sliding mode

    NASA Astrophysics Data System (ADS)

    Zhu, Zhenglong; Yan, Ye

    2014-09-01

    This paper addresses the issue of high-precision line-of-sight (LOS) tracking of geosynchronous earth orbit target in highly dynamic conditions via spacecraft attitude maneuver. First, characteristics of the LOS motion are analyzed by a simplified linear relative motion model. Second, after transforming the quaternion-based attitude model into a double integrator system, a new nonsingular terminal sliding mode controller is proposed for spacecraft attitude tracking in a nominal case without parametric uncertainties and external disturbances. Third, an adaptive new nonsingular terminal mode controller is proposed for spacecraft attitude tracking in an uncertain case, which is done via constructing a pair of adaptive laws to estimate the parametric uncertainties and external disturbances online. The robust stability and finite time convergence property of the closed-loop system are demonstrated by Lyapunov theorem. Under control of the proposed controller, zero steady state error tracking of LOS with a smooth transition phase can be achieved in scheduled time, regardless of parametric uncertainties and external disturbances online. Finally, detailed numerical simulation results are presented to illustrate the effectiveness and performance of the proposed controllers. Contrasting simulation results shows that proposed controllers can track the desired trajectories effectively and have better performance against the controllers based on linear sliding mode and the existing fast nonsingular terminal sliding mode.

  10. QUALITY ASSESSMENT OF CONFOCAL MICROSCOPY SLIDE-BASED SYSTEMS: INSTABLITY

    EPA Science Inventory

    Background: All slide-based fluorescence cytometry detections systems basically include an excitation light source, intermediate optics, and a detection device (CCD or PMT). Occasionally, this equipment becomes unstable, generating unreliable and inferior data. Methods: A num...

  11. DETAIL OF WEST END SLIDING DOOR AND EAVE VENTS ON ...

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

    DETAIL OF WEST END SLIDING DOOR AND EAVE VENTS ON THE SOUTH SIDE - Hickam Field, Practice Bomb Loading Shed, Bomb Storage Road near the intersection of Moffet and Kamakahi Streets, Honolulu, Honolulu County, HI

  12. BASEMENT, A view looking southwest toward the three panel, sliding ...

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

    BASEMENT, A view looking southwest toward the three panel, sliding glass door of walk-in hood and dial guage - Department of Energy, Mound Facility, Hydrolysis House Building (HH Building), One Mound Road, Miamisburg, Montgomery County, OH

  13. 2. WEST ELEVATION, SHOWING TAILRACE AND SLIDING DOOR UNDER SHED ...

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

    2. WEST ELEVATION, SHOWING TAILRACE AND SLIDING DOOR UNDER SHED ROOF. ADMINISTRATIVE OFFICE IS IN BACKGROUND AT RIGHT. VIEW TO EAST-NORTHEAST. - Santa Ana River Hydroelectric System, SAR-3 Powerhouse, San Bernardino National Forest, Redlands, San Bernardino County, CA

  14. 19. INTERIOR OF NORTHEAST REAR BEDROOM SHOWING ALUMINUMFRAME SLIDING GLASS ...

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

    19. INTERIOR OF NORTHEAST REAR BEDROOM SHOWING ALUMINUM-FRAME SLIDING GLASS WINDOWS. VIEW TO NORTHEAST. - Bishop Creek Hydroelectric System, Plant 4, Worker Cottage, Bishop Creek, Bishop, Inyo County, CA

  15. 21. INTERIOR OF SOUTHEAST REAR BEDROOM SHOWING ALUMINUMFRAME SLIDING GLASS ...

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

    21. INTERIOR OF SOUTHEAST REAR BEDROOM SHOWING ALUMINUM-FRAME SLIDING GLASS WINDOWS. VIEW TO SOUTHEAST. - Bishop Creek Hydroelectric System, Plant 4, Worker Cottage, Bishop Creek, Bishop, Inyo County, CA

  16. 30 CFR 816.99 - Slides and other damage.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... § 816.99 Slides and other damage. (a) An undisturbed natural barrier shall be provided beginning at the... determined by the regulatory authority as is needed to assure stability. The barrier shall be retained...

  17. 32. DETAIL OF CONCRETE TOWER AND SLIDE GATE LIFTING GEARS ...

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

    32. DETAIL OF CONCRETE TOWER AND SLIDE GATE LIFTING GEARS ON HEADWORKS OF DEER FLAT LOW LINE CANAL ON LOWER EMBANKMENT. VIEW TO SOUTHEAST. - Boise Project, Deer Flat Embankments, Lake Lowell, Nampa, Canyon County, ID

  18. 13. DETAIL OF CONCRETE TOWER AND SLIDE GATE LIFTING GEARS ...

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

    13. DETAIL OF CONCRETE TOWER AND SLIDE GATE LIFTING GEARS ON HEADWORKS OF DEER FLAT NAMPA CANAL ON UPPER EMBANKMENT. VIEW TO SOUTHWEST. - Boise Project, Deer Flat Embankments, Lake Lowell, Nampa, Canyon County, ID

  19. 17. Sliding access doors typical of those covering opening to ...

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

    17. Sliding access doors typical of those covering opening to filtration bed. - Lake Whitney Water Filtration Plant, Filtration Plant, South side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

  20. Detail of the exterior "selfclosing" sliding door with vent above. ...

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

    Detail of the exterior "self-closing" sliding door with vent above. View facing northeast - U.S. Naval Base, Pearl Harbor, Paint & Oil Storehouse, Avenue D near Seventh Street intersection, Pearl City, Honolulu County, HI