Science.gov

Sample records for actuator sliding rod

  1. 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

  2. Temperature actuated automatic safety rod release

    DOEpatents

    Hutter, Ernest; Pardini, John A.; Walker, David E.

    1987-01-01

    A temperature-actuated apparatus is disclosed for releasably supporting a safety rod in a nuclear reactor, comprising a safety rod upper adapter having a retention means, a drive shaft which houses the upper adapter, and a bimetallic means supported within the drive shaft and having at least one ledge which engages a retention means of the safety rod upper adapter. A pre-determined increase in temperature causes the bimetallic means to deform so that the ledge disengages from the retention means, whereby the bimetallic means releases the safety rod into the core of the reactor.

  3. Temperature actuated automatic safety rod release

    DOEpatents

    Hutter, E.; Pardini, J.A.; Walker, D.E.

    1984-03-13

    A temperature-actuated apparatus is disclosed for releasably supporting a safety rod in a nuclear reactor, comprising a safety rod upper adapter having a retention means, a drive shaft which houses the upper adapter, and a bimetallic means supported within the drive shaft and having at least one ledge which engages a retention means of the safety rod upper adapter. A pre-determined increase in temperature causes the bimetallic means to deform so that the ledge disengages from the retention means, whereby the bimetallic means releases the safety rod into the core of the reactor.

  4. Application of polyimide actuator rod seals

    NASA Technical Reports Server (NTRS)

    Watermann, A. W.; Gay, B. F.; Robinson, E. D.; Srinath, S. K.; Nelson, W. G.

    1972-01-01

    Development of polyimide two-stage hydraulic actuator rod seals for application in high-performance aircraft was accomplished. The significant portion of the effort was concentrated on optimization of the chevron and K-section second-stage seal geometries to satisfy the requirements for operation at 450 K (350 F) with dynamic pressure loads varying between 200 psig steady-state and 1500 psig impulse cycling. Particular significance was placed on reducing seal gland dimension by efficiently utilizing the fatigue allowables of polyimide materials. Other objectives included investigation of pressure balancing techniques for first-stage polyimide rod seals for 4000 psig 450 K(350 F) environment and fabrication of a modular retainer for the two-stage combination. Seals were fabricated in 0.0254 m (1.0in.) and 0.0635 m (2.5in.) sizes and tested for structural integrity, frictional resistance, and endurance life. Test results showed that carefully designed second stages using polyimides could be made to satisfy the dynamic return pressure requirements of applications in high-performance aircraft. High wear under full system pressure indicated that further research is necessary to obtain an acceptable first-stage design. The modular retainer was successfully tested and showed potential for new actuator applications.

  5. Adaptive sliding mode control of tri-layer conjugated polymer actuators

    NASA Astrophysics Data System (ADS)

    Wang, Xiangjiang; Alici, Gursel; Nguyen, Chuc Huu

    2013-02-01

    This paper proposes an adaptive sliding mode control methodology to enhance the positioning ability of conducting polymer actuators typified by tri-layer conjugated polymer actuators. This is motivated by the search for an effective control strategy to command such actuators to a desired configuration in the presence of parametric uncertainties and unmodeled disturbances. After analyzing the stability of the adaptive sliding mode control system, experiments were conducted to demonstrate its satisfactory tracking ability, based on a series of experimental results. Implementation of the control law requires a valid model of the conducting polymer actuator and boundaries of the uncertainties and disturbances. Based on the theoretical and experimental results presented, the adaptive sliding mode control methodology is very attractive in the field of smart actuators which contain significant uncertainties and disturbances.

  6. Robustness and Actuator Bandwidth of MRP-Based Sliding Mode Control for Spacecraft Attitude Control Problems

    NASA Astrophysics Data System (ADS)

    Keum, Jung-Hoon; Ra, Sung-Woong

    2009-12-01

    Nonlinear sliding surface design in variable structure systems for spacecraft attitude control problems is studied. A robustness analysis is performed for regular form of system, and calculation of actuator bandwidth is presented by reviewing sliding surface dynamics. To achieve non-singular attitude description and minimal parameterization, spacecraft attitude control problems are considered based on modified Rodrigues parameters (MRP). It is shown that the derived controller ensures the sliding motion in pre-determined region irrespective of unmodeled effects and disturbances.

  7. Design and finite element analysis of a novel sliding rod microscrew implantation device for mandibular prognathism

    PubMed Central

    Li, Yanfeng; Lv, Yuan; Lu, Yongjin; Zeng, Pan; Zeng, Xianglong; Guo, Xiaoqian; Han, Weili

    2015-01-01

    Tooth distalization is an effective approach for mandibular prognathism. Current distalization devices are bulky and clinically complicated. Here, we designed a novel molar distalization device by using a sliding rod and a microscrew and performed a mechanical analysis and finite element model (FEM) analysis of force distribution and displacement of the upper canine, first and second premolar and first molar. A 2D FEM was constructed using the Beam3 element and a 3D FEM was constructed of the mandibular teeth, the periodontal membrane, and the alveolar bones using the UG software. The upper first molar was divided into 12 points on the dental surface to facilitate stress analysis. Force analysis using the ANSYS WORKBECNH revealed that, both horizontally and vertically, the traction force causing distalization of the first molar decreased when the spring coil moved down the L shaped sliding rod. The 3D FEM force analysis revealed distomedial displacement of the upper first molar when the sliding rod microscrew implantation device caused distalization of the molar. These findings support further exploration for the use of the sliding rod microscrew implants as an anchorage for group distal movement of the teeth of patients with mandibular prognathism. PMID:26379860

  8. High-temperature, long-life polyimide seals for hydraulic actuator rods

    NASA Technical Reports Server (NTRS)

    Johnson, R. L.; Lee, J.; Loomis, W. R.

    1971-01-01

    Two types of polyimide seals are developed for hydraulic actuator rod in low pressure second stage of two-stage configuration. Each seal melts test objectives of twenty million cycles of operation at 534 K. Analytical and experimental study results are discussed. Potential applications are given.

  9. Decentralized sliding-mode control for spacecraft attitude synchronization under actuator failures

    NASA Astrophysics Data System (ADS)

    Wu, Baolin; Wang, Danwei; Poh, Eng Kee

    2014-12-01

    This paper examines attitude synchronization and tracking problems with model uncertainties, external disturbances, actuator failures and control torque saturation. Two decentralized sliding mode control laws are proposed and analyzed based on algebraic graph theory. Using Barbalat's Lemma, it is shown that the control laws guarantee each spacecraft approaches the desired time-varying attitude and angular velocity while maintaining attitude synchronization among the other spacecraft in the formation. The first controller is designed in the presence of model uncertainties, external disturbances, and actuator failures. The results are extended to the case with control input saturation in the second controller. Both control laws do not require online identification of failures. Numerical simulations are presented to show the effectiveness of the proposed attitude synchronization and tracking approaches.

  10. Rigid-rod anion-pi slides for multiion hopping across lipid bilayers.

    PubMed

    Gorteau, Virginie; Bollot, Guillaume; Mareda, Jiri; Matile, Stefan

    2007-09-21

    Shape-persistent oligo-p-phenylene-N,N-naphthalenediimide (O-NDI) rods are introduced as anion-pi slides for chloride-selective multiion hopping across lipid bilayers. Results from end-group engineering and covalent capture as O-NDI hairpins suggested that self-assembly into transmembrane O-NDI bundles is essential for activity. A halide topology VI (Cl > F > Br approximately I, Cl/Br approximately Cl/I > 7) implied strong anion binding along the anion-pi slides with relatively weak contributions from size exclusion (F >or= OAc). Anomalous mole fraction effects (AMFE) supported the occurrence of multiion hopping along the pi-acidic O-NDI rods. The existence of anion-pi interactions was corroborated by high-level ab initio and DFT calculations. The latter revealed positive NDI quadrupole moments far beyond the hexafluorobenzene standard. Computational studies further suggested that anion binding occurs at the confined, pi-acidic edges of the sticky NDI surface and is influenced by the nature of the phenyl spacer between two NDIs. With regard to methods development, a detailed analysis of the detection of ion selectivity with the HPTS assay including AMFE in vesicles is provided. PMID:17728867

  11. Tracking Control of a Magnetic Shape Memory Actuator Using an Inverse Preisach Model with Modified Fuzzy Sliding Mode Control.

    PubMed

    Lin, Jhih-Hong; Chiang, Mao-Hsiung

    2016-01-01

    Magnetic shape memory (MSM) alloys are a new class of smart materials with extraordinary strains up to 12% and frequencies in the range of 1 to 2 kHz. The MSM actuator is a potential device which can achieve high performance electromagnetic actuation by using the properties of MSM alloys. However, significant non-linear hysteresis behavior is a significant barrier to control the MSM actuator. In this paper, the Preisach model was used, by capturing experiments from different input signals and output responses, to model the hysteresis of MSM actuator, and the inverse Preisach model, as a feedforward control, provided compensational signals to the MSM actuator to linearize the hysteresis non-linearity. The control strategy for path tracking combined the hysteresis compensator and the modified fuzzy sliding mode control (MFSMC) which served as a path controller. Based on the experimental results, it was verified that a tracking error in the order of micrometers was achieved. PMID:27571081

  12. Fuzzy-neural-network inherited sliding-mode control for robot manipulator including actuator dynamics.

    PubMed

    Wai, Rong-Jong; Muthusamy, Rajkumar

    2013-02-01

    This paper presents the design and analysis of an intelligent control system that inherits the robust properties of sliding-mode control (SMC) for an n-link robot manipulator, including actuator dynamics in order to achieve a high-precision position tracking with a firm robustness. First, the coupled higher order dynamic model of an n-link robot manipulator is briefy introduced. Then, a conventional SMC scheme is developed for the joint position tracking of robot manipulators. Moreover, a fuzzy-neural-network inherited SMC (FNNISMC) scheme is proposed to relax the requirement of detailed system information and deal with chattering control efforts in the SMC system. In the FNNISMC strategy, the FNN framework is designed to mimic the SMC law, and adaptive tuning algorithms for network parameters are derived in the sense of projection algorithm and Lyapunov stability theorem to ensure the network convergence as well as stable control performance. Numerical simulations and experimental results of a two-link robot manipulator actuated by DC servo motors are provided to justify the claims of the proposed FNNISMC system, and the superiority of the proposed FNNISMC scheme is also evaluated by quantitative comparison with previous intelligent control schemes. PMID:24808281

  13. Two modified discrete PID-based sliding mode controllers for piezoelectric actuators

    NASA Astrophysics Data System (ADS)

    Cao, Y.; Chen, X. B.

    2014-01-01

    Hysteresis is a nonlinear effect that can result in the degraded performance of piezoelectric actuators (PEAs). To counteract the effect, several control methods have been developed and reported in the literature. One promising method for compensation is the use of a proportional-integral-derivative (PID)-based sliding mode control (SMC), in which the PEA hysteresis is treated as an unknown disturbance to the PEA input. If the hysteresis can be modelled or partially modelled, the integration of the hysteresis models into the control schemes may lead to further improved performance. On this philosophy, this paper presents the development of two modified discrete PID-based sliding mode controllers (PID-SMCs) for the PEAs, namely an inversion-based PID-SMC and a disturbance-observer (DOB)-based PID-SMC, in which the PEA hysteresis is predicted or partially predicted through the use of existing models for the PEA hysteresis. Experiments were performed to verify the effectiveness of the proposed control schemes. The results were compared to those of the nominal PID-SMC. By employing the inversion hysteresis and the DOB, the PEA performance was greatly improved.

  14. Development of a HTSMA-Actuated Surge Control Rod for High-Temperature Turbomachinery Applications

    NASA Technical Reports Server (NTRS)

    Padula, Santo, II; Noebe, Ronald; Bigelow, Glen; Culley, Dennis; Stevens, Mark; Penney, Nicholas; Gaydosh, Darrell; Quackenbush, Todd; Carpenter, Bernie

    2007-01-01

    In recent years, a demand for compact, lightweight, solid-state actuation systems has emerged, driven in part by the needs of the aeronautics industry. However, most actuation systems used in turbomachinery require not only elevated temperature but high-force capability. As a result, shape memory alloy (SMA) based systems have worked their way to the forefront of a short list of viable options to meet such a technological challenge. Most of the effort centered on shape memory systems to date has involved binary NiTi alloys but the working temperatures required in many aeronautics applications dictate significantly higher transformation temperatures than the binary systems can provide. Hence, a high temperature shape memory alloy (HTSMA) based on NiTiPdPt, having a transformation temperature near 300 C, was developed. Various thermo-mechanical processing schemes were utilized to further improve the dimensional stability of the alloy and it was later extruded/drawn into wire form to be more compatible with envisioned applications. Mechanical testing on the finished wire form showed reasonable work output capability with excellent dimensional stability. Subsequently, the wire form of the alloy was incorporated into a benchtop system, which was shown to provide the necessary stroke requirements of approx.0.125 inches for the targeted surge-control application. Cycle times for the actuator were limited to 4 seconds due to control and cooling constraints but this cycle time was determined to be adequate for the surge control application targeted as the primary requirement was initial actuation of a surge control rod, which could be completed in approximately one second.

  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. Fault-tolerant control of electric vehicles with in-wheel motors using actuator-grouping sliding mode controllers

    NASA Astrophysics Data System (ADS)

    Li, Boyuan; Du, Haiping; Li, Weihua

    2016-05-01

    Although electric vehicles with in-wheel motors have been regarded as one of the promising vehicle architectures in recent years, the probability of in-wheel motor fault is still a crucial issue due to the system complexity and large number of control actuators. In this study, a modified sliding mode control (SMC) is applied to achieve fault-tolerant control of electric vehicles with four-wheel-independent-steering (4WIS) and four-wheel-independent-driving (4WID). Unlike in traditional SMC, in this approach the steering geometry is re-arranged according to the location of faulty wheels in the modified SMC. Three SMC control laws for longitudinal velocity control, lateral velocity control and yaw rate control are designed based on specific vehicle motion scenarios. In addition the actuator-grouping SMC method is proposed so that driving actuators are grouped and each group of actuators can be used to achieve the specific control target, which avoids the strong coupling effect between each control target. Simulation results prove that the proposed modified SMC can achieve good vehicle dynamics control performance in normal driving and large steering angle turning scenarios. In addition, the proposed actuator-grouping SMC can solve the coupling effect of different control targets and the control performance is improved.

  17. 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

  18. 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

  19. INDIRECT INTELLIGENT SLIDING MODE CONTROL OF A SHAPE MEMORY ALLOY ACTUATED FLEXIBLE BEAM USING HYSTERETIC RECURRENT NEURAL NETWORKS

    PubMed Central

    Hannen, Jennifer C.; Crews, John H.; Buckner, Gregory D.

    2012-01-01

    This paper introduces an indirect intelligent sliding mode controller (IISMC) for shape memory alloy (SMA) actuators, specifically a flexible beam deflected by a single offset SMA tendon. The controller manipulates applied voltage, which alters SMA tendon temperature to track reference bending angles. A hysteretic recurrent neural network (HRNN) captures the nonlinear, hysteretic relationship between SMA temperature and bending angle. The variable structure control strategy provides robustness to model uncertainties and parameter variations, while effectively compensating for system nonlinearities, achieving superior tracking compared to an optimized PI controller. PMID:22962538

  20. 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

  1. Sliding mode attitude control with L 2-gain performance and vibration reduction of flexible spacecraft with actuator dynamics

    NASA Astrophysics Data System (ADS)

    Hu, Qinglei

    2010-09-01

    This paper presents a dual-stage control system design method for the rotational maneuver control and vibration stabilization of a flexible spacecraft. In this design approach, the sub-systems of attitude control and vibration suppression are designed separately using the low order model. Based on the sliding mode control (SMC) theory, a discontinuous attitude control law in the form of the input voltage of the reaction wheel is derived to control the orientation of the spacecraft, incorporating the L 2-gain performance criterion constraint. The resulting closed-loop system is proven to be uniformly ultimately bounded stability and the effect of the external disturbance on both attitude quaternion and angular velocity can be attenuated to the prescribed level as well. In addition, an adaptive version of the control law is designed for adapting the unknown upper bounds of the lumped disturbance such that the limitation of knowing the bound of the disturbance in advance is released. For actively suppressing the induced vibration, strain rate feedback control method is also investigated by using piezoelectric materials as additional sensors and actuators bonded on the surface of the flexible appendages. Numerical simulations are performed to show that rotational maneuver and vibration suppression are accomplished in spite of the presence of disturbance and uncertainty.

  2. A new type of a direct-drive valve system driven by a piezostack actuator and sliding spool

    NASA Astrophysics Data System (ADS)

    Jeon, Juncheol; Han, Chulhee; Han, Young-Min; Choi, Seung-Bok

    2014-07-01

    A direct-drive valve (DDV) system is a kind of electrohydraulic servo valve system, in which the actuator directly drives the spool of the valve. In conventional DDV systems, the spool is generally driven by an electromagnetic actuator. Performance characteristics such as frequency bandwidth of DDV systems driven by the electromagnetic actuator are limited due to the actuator response property. In order to improve the performance characteristics of conventional DDV systems, in this work a new configuration for a direct-drive valve system actuated by a piezostack actuator with a flexible beam mechanism is proposed (in short, a piezo-driven DDV system). Its benefits are demonstrated through both simulation and experiment. After describing the geometric configuration and operational principle of the proposed valve system, a governing equation of the whole system is obtained by combining the dynamic equations of the fluid part and the structural parts: the piezostack, the flexible beam, and the spool. In the structural parts of the piezostack and flexible beam, a lumped parameter modeling method is used, while the conventional rule of the fluid momentum is used for the fluid part. In order to evaluate valve performances of the proposed system, an experimental apparatus consisting of a hydraulic circuit and the piezo-driven DDV system is established. The performance characteristics are evaluated in terms of maximum spool displacement, flow rate, frequency characteristics, and step response. In addition, in order to advocate the feasibility of the proposed dynamic model, a comparison between simulation and experiment is undertaken.

  3. Development and testing of improved polyimide actuator rod seals at higher temperatures for use in advanced aircraft hydraulic systems

    NASA Technical Reports Server (NTRS)

    Robinson, E. D.; Waterman, A. W.; Nelson, W. G.

    1972-01-01

    Polyimide second stage rod seals were evaluated to determine their suitability for application in advanced aircraft systems. The configurations of the seals are described. The conditions of the life cycle tests are provided. It was determined that external rod seal leakage was within prescribed limits and that the seals showed no signs of structural degradation.

  4. Testing of improved polyimide actuator rod seals at high temperature and under vacuum conditions for use in advanced aircraft hydraulic systems

    NASA Technical Reports Server (NTRS)

    Sellereite, B. K.; Waterman, A. W.; Nelson, W. G.

    1974-01-01

    Polyimide second-stage rod seals were evaluated to determine their suitability for applications in space station environments. The 6.35-cm (2.5-in.)K-section seal was verified for thermal cycling operation between room temperature and 478 K (400 F) and for operation in a 133 micron PA(0.000001 mm Hg) vacuum environment. The test seal completed the scheduled 96 thermal cycles and 1438 hr in vacuum with external rod seal leakage well within the maximum allowable of two drops per 25 actuation cycles. At program completion, the seals showed no signs of structural degradation. Posttest inspection showed the seals retained a snug fit against the shaft and housing walls, indicating additional wear life capability. Evaluation of a molecular flow section during vacuum testing, to inhibit fluid loss through vaporization, showed it to be beneficial with MIL-H-5606, a petroleum-base fluid, in comparison with MIL-H-83282, a synthetic hydrocarbon-base fluid.

  5. Pneumatic actuator with hydraulic control

    NASA Astrophysics Data System (ADS)

    Everett, Hobart R., Jr.

    1992-11-01

    The present invention provides a pneumatically powered actuator having hydraulic control for both locking and controlling the velocity of an output rod without any sponginess. The invention includes a double-acting pneumatic actuator having a bore, a piston slidably engaged within the bore, and a control rod connected to the piston. The double-acting pneumatic actuator is mounted to a frame. A first double-acting hydraulic actuator having a bore, a piston slidably engaged within the bore, and a follower rod mounted to the piston is mounted to the frame such that the follower rod is fixedly connected to the control rod. The maximum translation of the piston within the bore of the first double-acting hydraulic actuator provides a volumetric displacement V1. The present invention also includes a second double-acting hydraulic actuator having a bore, a piston slidably engaged within the bore, and an output rod mounted to the piston. The maximum translation of the piston within the bore of the second double-acting hydraulic actuator provides a volumetric displacement V2, where V2=V1. A pair of fluid ports in each of the first and second double-acting hydraulic cylinders are operably connected by fluid conduits, one of which includes a valve circuit which may be used to control the velocity of the output rod or to lock the output rod in a static position by regulating the flow of hydraulic fluid between the double-acting cylinders.

  6. Control rod drive

    SciTech Connect

    Hawke, Basil C.

    1986-01-01

    A control rod drive uses gravitational forces to insert one or more control rods upwardly into a reactor core from beneath the reactor core under emergency conditions. The preferred control rod drive includes a vertically movable weight and a mechanism operatively associating the weight with the control rod so that downward movement of the weight is translated into upward movement of the control rod. The preferred control rod drive further includes an electric motor for driving the control rods under normal conditions, an electrically actuated clutch which automatically disengages the motor during a power failure and a decelerator for bringing the control rod to a controlled stop when it is inserted under emergency conditions into a reactor core.

  7. Improved Electrohydraulic Linear Actuators

    NASA Technical Reports Server (NTRS)

    Hamtil, James

    2004-01-01

    A product line of improved electrohydraulic linear actuators has been developed. These actuators are designed especially for use in actuating valves in rocket-engine test facilities. They are also adaptable to many industrial uses, such as steam turbines, process control valves, dampers, motion control, etc. The advantageous features of the improved electrohydraulic linear actuators are best described with respect to shortcomings of prior electrohydraulic linear actuators that the improved ones are intended to supplant. The flow of hydraulic fluid to the two ports of the actuator cylinder is controlled by a servo valve that is controlled by a signal from a servo amplifier that, in turn, receives an analog position-command signal (a current having a value between 4 and 20 mA) from a supervisory control system of the facility. As the position command changes, the servo valve shifts, causing a greater flow of hydraulic fluid to one side of the cylinder and thereby causing the actuator piston to move to extend or retract a piston rod from the actuator body. A linear variable differential transformer (LVDT) directly linked to the piston provides a position-feedback signal, which is compared with the position-command signal in the servo amplifier. When the position-feedback and position-command signals match, the servo valve moves to its null position, in which it holds the actuator piston at a steady position.

  8. Biomimetic actuator

    NASA Astrophysics Data System (ADS)

    Bouda, Vaclav; Boudova, Lea; Haluzikova, Denisa

    2005-05-01

    The aim of the presentation is to propose an alternative model of mammalian skeletal muscle function, which reflects the simplicity of nature and can be applied in engineering. Van der Waals attractive and repulsive electrostatic forces are assumed to control the design of internal structures and functions of contractile units of the muscles - sarcomere. The role of myosin heads is crucial for the higher order formation. The model of the myosin head lattice is the working model for the sarcomere contraction interpretation. The contraction is interpreted as a calcium induced phase transition of the lattice, which results in relative actin-myosin sliding and/or force generation. The model should provide the engineering science with a simple analogy to technical actuators of high performance.

  9. Hydraulically actuated well shifting tool

    SciTech Connect

    Roth, B.A.

    1992-10-20

    This patent describes a hydraulically actuated shifting tool for actuating a sliding member in a well tool. It comprises: a housing having a hydraulic fluid bore therein; shifting dog means positioned on the housing for movement away and toward the housing; locking dog means positioned on the housing for movement away and toward the body; shifting dog hydraulic actuating means in fluid communication with the bore for causing engagement of the shifting dogs with the sliding member; locking dog hydraulic actuating means in communication with the bore for causing engagement of the locking dogs with the locking means; and hydraulic shifting means in communication with the bore for causing relative movement between the shifting dog means and the locking dog means for shifting the sliding sleeve.

  10. Protein-Protein Interactions Leading to Recruitment of the Host DNA Sliding Clamp by the Hyperthermophilic Sulfolobus islandicus Rod-Shaped Virus 2

    PubMed Central

    Gardner, Andrew F.; Bell, Stephen D.; White, Malcolm F.

    2014-01-01

    Viruses infecting hyperthermophilic archaea typically do not encode DNA polymerases, raising questions regarding their genome replication. Here, using a yeast two-hybrid approach, we have assessed interactions between proteins of Sulfolobus islandicus rod-shaped virus 2 (SIRV2) and the host-encoded proliferating cell nuclear antigen (PCNA), a key DNA replication protein in archaea. Five SIRV2 proteins were found to interact with PCNA, providing insights into the recruitment of host replisome for viral DNA replication. PMID:24696494

  11. Automatic safety rod for reactors

    DOEpatents

    Germer, John H.

    1988-01-01

    An automatic safety rod for a nuclear reactor containing neutron absorbing material and designed to be inserted into a reactor core after a loss-of-core flow. Actuation is based upon either a sudden decrease in core pressure drop or the pressure drop decreases below a predetermined minimum value. The automatic control rod includes a pressure regulating device whereby a controlled decrease in operating pressure due to reduced coolant flow does not cause the rod to drop into the core.

  12. Rodding Surgery

    MedlinePlus

    ... Rods can be made of stainless steel or titanium. Regular rods do not expand. They have many ... v regular), the rod materials (stainless steel v titanium) and the age for a first rodding surgery. ...

  13. Lead screw linear actuator

    NASA Technical Reports Server (NTRS)

    Perkins, Gerald S. (Inventor)

    1980-01-01

    A linear actuator which can apply high forces is described, which includes a reciprocating rod having a threaded portion engaged by a nut that is directly coupled to the rotor of an electric motor. The nut is connected to the rotor in a manner that minimizes loading on the rotor, by the use of a coupling that transmits torque to the nut but permits it to shift axially and radially with respect to the rotor. The nut has a threaded hydrostatic bearing for engaging the threaded rod portion, with an oilcarrying groove in the nut being interrupted.

  14. Handbuilt Slides.

    ERIC Educational Resources Information Center

    Gatto, Joseph

    1979-01-01

    The author suggests handbuilt slides as an art project for elementary or secondary students. Instructions are given for making slides with found objects, smoke, and magazine lifts. The article is illustrated with several examples of this technique. (SJL)

  15. Method and apparatus for actuating vehicle transmission

    SciTech Connect

    Ishida, H.; Ishihara, M.; Uriuhara, M.

    1988-11-15

    This patent describes a method of actuating a vehicle parallel-gear transmission having gears and an internal lever for moving shift blocks connected with shift rods and shift forks for changing gear ratios of the transmission, a hydraulically controlled select actuator operatively connected to the internal lever for moving the internal lever in a select direction, a hydraulically controlled shift actuator operatively connected to the internal lever for moving the internal lever in a shift direction substantially normal to the select direction, a hydraulically controlled clutch actuator for connecting and disconnecting a clutch of the transmission, and a common fluid discharge passage connected to fluid discharge ports of the select and shift actuators and a fluid discharge port of the clutch actuator, the select and shift actuators being alternately actuatable to effect a gear changing operation.

  16. Automatic safety rod for reactors. [LMFBR

    DOEpatents

    Germer, J.H.

    1982-03-23

    An automatic safety rod for a nuclear reactor containing neutron absorbing material and designed to be inserted into a reactor core after a loss-of-flow. Actuation is based upon either a sudden decrease in core pressure drop or the pressure drop decreases below a predetermined minimum value. The automatic control rod includes a pressure regulating device whereby a controlled decrease in operating pressure due to reduced coolant flow does not cause the rod to drop into the core.

  17. Low-Temperature Seal for Actuator Rod

    NASA Technical Reports Server (NTRS)

    Lindfors, R. J.

    1985-01-01

    Combination bearing and seal used on Space Shuttle functions reliably at temperatures as low as - 160 degrees F and as high as + 130 degrees F. Corrosion-resistant stainless-steel spacer separates secondary and primary seals in both old and new versions of seal assembly. In new version, combination of flexible sealing lip and bridge is less susceptible to cracking at low temperatures.

  18. Nuclear radiation actuated valve

    DOEpatents

    Christiansen, David W.; Schively, Dixon P.

    1985-01-01

    A nuclear radiation actuated valve for a nuclear reactor. The valve has a valve first part (such as a valve rod with piston) and a valve second part (such as a valve tube surrounding the valve rod, with the valve tube having side slots surrounding the piston). Both valve parts have known nuclear radiation swelling characteristics. The valve's first part is positioned to receive nuclear radiation from the nuclear reactor's fuel region. The valve's second part is positioned so that its nuclear radiation induced swelling is different from that of the valve's first part. The valve's second part also is positioned so that the valve's first and second parts create a valve orifice which changes in size due to the different nuclear radiation caused swelling of the valve's first part compared to the valve's second part. The valve may be used in a nuclear reactor's core coolant system.

  19. Thermally Actuated Hydraulic Pumps

    NASA Technical Reports Server (NTRS)

    Jones, Jack; Ross, Ronald; Chao, Yi

    2008-01-01

    Thermally actuated hydraulic pumps have been proposed for diverse applications in which direct electrical or mechanical actuation is undesirable and the relative slowness of thermal actuation can be tolerated. The proposed pumps would not contain any sliding (wearing) parts in their compressors and, hence, could have long operational lifetimes. The basic principle of a pump according to the proposal is to utilize the thermal expansion and contraction of a wax or other phase-change material in contact with a hydraulic fluid in a rigid chamber. Heating the chamber and its contents from below to above the melting temperature of the phase-change material would cause the material to expand significantly, thus causing a substantial increase in hydraulic pressure and/or a substantial displacement of hydraulic fluid out of the chamber. Similarly, cooling the chamber and its contents from above to below the melting temperature of the phase-change material would cause the material to contract significantly, thus causing a substantial decrease in hydraulic pressure and/or a substantial displacement of hydraulic fluid into the chamber. The displacement of the hydraulic fluid could be used to drive a piston. The figure illustrates a simple example of a hydraulic jack driven by a thermally actuated hydraulic pump. The pump chamber would be a cylinder containing encapsulated wax pellets and containing radial fins to facilitate transfer of heat to and from the wax. The plastic encapsulation would serve as an oil/wax barrier and the remaining interior space could be filled with hydraulic oil. A filter would retain the encapsulated wax particles in the pump chamber while allowing the hydraulic oil to flow into and out of the chamber. In one important class of potential applications, thermally actuated hydraulic pumps, exploiting vertical ocean temperature gradients for heating and cooling as needed, would be used to vary hydraulic pressures to control buoyancy in undersea research

  20. Piezoelectric step-motion actuator

    DOEpatents

    Mentesana; Charles P.

    2006-10-10

    A step-motion actuator using piezoelectric material to launch a flight mass which, in turn, actuates a drive pawl to progressively engage and drive a toothed wheel or rod to accomplish stepped motion. Thus, the piezoelectric material converts electrical energy into kinetic energy of the mass, and the drive pawl and toothed wheel or rod convert the kinetic energy of the mass into the desired rotary or linear stepped motion. A compression frame may be secured about the piezoelectric element and adapted to pre-compress the piezoelectric material so as to reduce tensile loads thereon. A return spring may be used to return the mass to its resting position against the compression frame or piezoelectric material following launch. Alternative embodiment are possible, including an alternative first embodiment wherein two masses are launched in substantially different directions, and an alternative second embodiment wherein the mass is eliminated in favor of the piezoelectric material launching itself.

  1. Remotely operated gripper provides vertical control rod movement

    NASA Technical Reports Server (NTRS)

    Hutter, E.; Koch, L. J.

    1968-01-01

    Remote actuation of a gripper shaft affects vertical engagement between a drive shaft and control rod. A secondary function of the gripper is to provide remote indication of positive completion of the gripping or ungripping operation.

  2. Releasable High-Mechanical-Advantage Linear Actuator

    NASA Technical Reports Server (NTRS)

    Young, Gordon H.

    1994-01-01

    Proposed linear actuator includes ball-screw mechanism made to engage or disengage piston as needed. Requires low power to maintain release and no power to maintain engagement. Pins sliding radially in solenoids in yoke engage or disengage slot in piston. With help of optoelectronic feedback, yoke made to follow free piston during disengagement so always in position to "grab" piston.

  3. Actuated atomizer

    NASA Technical Reports Server (NTRS)

    Tilton, Charles (Inventor); Weiler, Jeff (Inventor); Palmer, Randall (Inventor); Appel, Philip (Inventor)

    2008-01-01

    An actuated atomizer is adapted for spray cooling or other applications wherein a well-developed, homogeneous and generally conical spray mist is required. The actuated atomizer includes an outer shell formed by an inner ring; an outer ring; an actuator insert and a cap. A nozzle framework is positioned within the actuator insert. A base of the nozzle framework defines swirl inlets, a swirl chamber and a swirl chamber. A nozzle insert defines a center inlet and feed ports. A spool is positioned within the coil housing, and carries the coil windings having a number of turns calculated to result in a magnetic field of sufficient strength to overcome the bias of the spring. A plunger moves in response to the magnetic field of the windings. A stop prevents the pintle from being withdrawn excessively. A pintle, positioned by the plunger, moves between first and second positions. In the first position, the head of the pintle blocks the discharge passage of the nozzle framework, thereby preventing the atomizer from discharging fluid. In the second position, the pintle is withdrawn from the swirl chamber, allowing the atomizer to release atomized fluid. A spring biases the pintle to block the discharge passage. The strength of the spring is overcome, however, by the magnetic field created by the windings positioned on the spool, which withdraws the plunger into the spool and further compresses the spring.

  4. Actuator-valve interface optimization. [Explosive actuators

    SciTech Connect

    Burchett, O.L.; Jones, R.L.

    1987-02-01

    The interface of explosive actuator driven valves can be optimized to maximize the velocity of the valve plunger by using the computer code Actuator-Valve Response. Details of the AVR model of the actuator driven valve plunger and the results of optimizing an actuator-valve interface with AVR are presented. 5 refs., 5 figs., 3 tabs.

  5. Rotary actuator

    NASA Technical Reports Server (NTRS)

    Brudnicki, Myron (Inventor)

    1995-01-01

    Rotary actuators and other mechanical devices incorporating shape memory alloys are provided herein. Shape memory alloys are a group of metals which when deformed at temperatures below their martensite temperatures, resume the shapes which they had prior to the deformation if they are heated to temperatures above their austensite temperatures. Actuators in which shape memory alloys are employed include bias spring types, in which springs deform the shape memory alloy (SMA), and differential actuators, which use two SMA members mechanically connected in series. Another type uses concentric cylindrical members. One member is in the form of a sleeve surrounding a cylinder, both being constructed of shape memory alloys. Herein two capstans are mounted on a shaft which is supported in a framework. Each capstan is capable of rotating the shaft. Shape memory wire, as two separate lengths of wire, is wrapped around each capstan to form a winding around that capstan. The winding on one capstan is so wrapped that the wire is in a prestretched state. The winding on the other capstan is so wrapped that the wire is in a taut, but not a prestretched, state. Heating one performs work in one direction, thus deforming the other one. When the other SMA is heated the action is reversed.

  6. Modular droplet actuator drive

    NASA Technical Reports Server (NTRS)

    Pollack, Michael G. (Inventor); Paik, Philip (Inventor)

    2011-01-01

    A droplet actuator drive including a detection apparatus for sensing a property of a droplet on a droplet actuator; circuitry for controlling the detection apparatus electronically coupled to the detection apparatus; a droplet actuator cartridge connector arranged so that when a droplet actuator cartridge electronically is coupled thereto: the droplet actuator cartridge is aligned with the detection apparatus; and the detection apparatus can sense the property of the droplet on a droplet actuator; circuitry for controlling a droplet actuator coupled to the droplet actuator connector; and the droplet actuator circuitry may be coupled to a processor.

  7. CONTROL ROD

    DOEpatents

    Zinn, W.H.; Ross, H.V.

    1958-11-18

    A control rod is described for a nuclear reactor. In certaln reactor designs it becomes desirable to use a control rod having great width but relatively llttle thickness. This patent is addressed to such a need. The neutron absorbing material is inserted in a triangular tube, leaving volds between the circular insert and the corners of the triangular tube. The material is positioned within the tube by the use of dummy spacers to achleve the desired absorption pattern, then the ends of the tubes are sealed with suitable plugs. The tubes may be welded or soldered together to form two flat surfaces of any desired width, and covered with sheetmetal to protect the tubes from damage. This design provides a control member that will not distort under the action of outside forces or be ruptured by gases generated within the jacketed control member.

  8. 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.

  9. Chattering-Free Sliding Mode Control with Unmodeled Dynamics

    NASA Technical Reports Server (NTRS)

    Krupp, Don; Shtessel, Yuri B.

    1999-01-01

    Sliding mode control systems are valued for their robust accommodation of uncertainties and their ability to reject disturbances. In this paper, a design methodology is proposed to eliminate the chattering phenomenon affecting sliding mode controlled plants with input unmodeled actuator dynamics of second order or greater. The proposed controller design is based on the relative degrees of the plant and the unmodeled actuator dynamics and the ranges of the uncertainties of the plant and actuator. The controller utilizes the pass filter characteristics of the physical actuating device to provide a smoothing effect on the discontinuous control signal rather than introducing any artificial dynamics into the controller design thus eliminating chattering in the system's output response.

  10. Memory metal actuator

    NASA Technical Reports Server (NTRS)

    Ruoff, C. F. (Inventor)

    1985-01-01

    A mechanical actuator can be constructed by employing a plurality of memory metal actuator elements in parallel to control the amount of actuating force. In order to facilitate direct control by digital control signals provided by a computer or the like, the actuating elements may vary in stiffness according to a binary relationship. The cooling or reset time of the actuator elements can be reduced by employing Peltier junction cooling assemblies in the actuator.

  11. Thermostatic Valves Containing Silicone-Oil Actuators

    NASA Technical Reports Server (NTRS)

    Bhandari, Pradeep; Birur, Gajanana C.; Bame, David P.; Karlmann, Paul B.; Prina, Mauro; Young, William; Fisher, Richard

    2009-01-01

    Flow-splitting and flow-mixing thermally actuated spool valves have been developed for controlling flows of a heat-transfer fluid in a temperature-regulation system aboard the Mars Science Laboratory (MSL) rover. Valves like these could also be useful in terrestrial temperature-regulation systems, including automobile air-conditioning systems and general refrigeration systems. These valves are required to provide smoother actuation over a wider temperature range than the flow-splitting, thermally actuated spool valves used in the Mars Explorer Rover (MER). Also, whereas the MER valves are unstable (tending to oscillate) in certain transition temperature ranges, these valves are required not to oscillate. The MER valves are actuated by thermal expansion of a wax against spring-loaded piston rods (as in common automotive thermostats). The MSL valves contain similar actuators that utilize thermal expansion of a silicone oil, because silicone-oil actuators were found to afford greater and more nearly linear displacements, needed for smoother actuation, over the required wider temperature range. The MSL valves also feature improved spool designs that reflect greater understanding of fluid dynamics, consideration of pressure drops in valves, and a requirement for balancing of pressures in different flow branches.

  12. Elastomeric actuator devices for magnetic resonance imaging

    NASA Technical Reports Server (NTRS)

    Dubowsky, Steven (Inventor); Hafez, Moustapha (Inventor); Jolesz, Ferenc A. (Inventor); Kacher, Daniel F. (Inventor); Lichter, Matthew (Inventor); Weiss, Peter (Inventor); Wingert, Andreas (Inventor)

    2008-01-01

    The present invention is directed to devices and systems used in magnetic imaging environments that include an actuator device having an elastomeric dielectric film with at least two electrodes, and a frame attached to the actuator device. The frame can have a plurality of configurations including, such as, for example, at least two members that can be, but not limited to, curved beams, rods, plates, or parallel beams. These rigid members can be coupled to flexible members such as, for example, links wherein the frame provides an elastic restoring force. The frame preferably provides a linear actuation force characteristic over a displacement range. The linear actuation force characteristic is defined as .+-.20% and preferably 10% over a displacement range. The actuator further includes a passive element disposed between the flexible members to tune a stiffness characteristic of the actuator. The passive element can be a bi-stable element. The preferred embodiment actuator includes one or more layers of the elastomeric film integrated into the frame. The elastomeric film can be made of many elastomeric materials such as, for example, but not limited to, acrylic, silicone and latex.

  13. Control rod for a nuclear reactor

    DOEpatents

    Roman, Walter G.; Sutton, Jr., Harry G.

    1979-01-01

    A control rod assembly for a nuclear reactor is disclosed having a remotely disengageable coupling between the control rod and the control rod drive shaft. The coupling is actuated by first lowering then raising the drive shaft. The described motion causes axial repositioning of a pin in a grooved rotatable cylinder, each being attached to different parts of the drive shaft which are axially movable relative to each other. In one embodiment, the relative axial motion of the parts of the drive shaft is used either to couple or to uncouple the connection by forcing resilient members attached to the drive shaft into or out of shouldered engagement, respectively, with an indentation formed in the control rod.

  14. A magnetorheological actuation system: test and model

    NASA Astrophysics Data System (ADS)

    John, Shaju; Chaudhuri, Anirban; Wereley, Norman M.

    2008-04-01

    Self-contained actuation systems, based on frequency rectification of the high frequency motion of an active material, can produce high force and stroke output. Magnetorheological (MR) fluids are active fluids whose rheological properties can be altered by the application of a magnetic field. By using MR fluids as the energy transmission medium in such hybrid devices, a valving system with no moving parts can be implemented and used to control the motion of an output cylinder shaft. The MR fluid based valves are configured in the form of an H-bridge to produce bi-directional motion in an output cylinder by alternately applying magnetic fields in the two opposite arms of the bridge. The rheological properties of the MR fluid are modeled using both Bingham plastic and bi-viscous models. In this study, the primary actuation is performed using a compact terfenol-D rod driven pump and frequency rectification of the rod motion is done using passive reed valves. The pump and reed valve configuration along with MR fluidic valves form a compact hydraulic actuation system. Actuator design, analysis and experimental results are presented in this paper. A time domain model of the actuator is developed and validated using experimental data.

  15. 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.

  16. Nuclear Storage Overpack Door Actuator and Alignment Apparatus

    DOEpatents

    Andreyko, Gregory M.

    2005-05-11

    The invention is a door actuator and alignment apparatus for opening and closing the 15,000-pound horizontally sliding door of a storage overpack. The door actuator includes a ball screw mounted horizontally on a rigid frame including a pair of door panel support rails. An electrically powered ball nut moves along the ball screw. The ball nut rotating device is attached to a carriage. The carriage attachment to the sliding door is horizontally pivoting. Additional alignment features include precision cam followers attached to the rails and rail guides attached to the carriage.

  17. Nuclear storage overpack door actuator and alignment apparatus

    SciTech Connect

    Andreyko, Gregory M.

    2005-05-10

    The invention is a door actuator and alignment apparatus for opening and closing the 15,000-pound horizontally sliding door of a storage overpack. The door actuator includes a ball screw mounted horizontally on a rigid frame including a pair of door panel support rails. An electrically powered ball nut moves along the ball screw. The ball nut rotating device is attached to a carriage. The carriage attachment to the sliding door is horizontally pivoting. Additional alignment features include precision cam followers attached to the rails and rail guides attached to the carriage.

  18. Powerful Electromechanical Linear Actuator

    NASA Technical Reports Server (NTRS)

    Cowan, John R.; Myers, William N.

    1994-01-01

    Powerful electromechanical linear actuator designed to replace hydraulic actuator that provides incremental linear movements to large object and holds its position against heavy loads. Electromechanical actuator cleaner and simpler, and needs less maintenance. Two principal innovative features that distinguish new actuator are use of shaft-angle resolver as source of position feedback to electronic control subsystem and antibacklash gearing arrangement.

  19. Bistable (latching) solenoid actuated propellant isolation valve

    NASA Technical Reports Server (NTRS)

    Wichmann, H.; Deboi, H. H.

    1979-01-01

    The design, fabrication, assembly and test of a development configuration bistable (latching) solenoid actuated propellant isolation valve suitable for the control hydrazine and liquid fluorine to an 800 pound thrust rocket engine is described. The valve features a balanced poppet, utilizing metal bellows, a hard poppet/seat interface and a flexure support system for the internal moving components. This support system eliminates sliding surfaces, thereby rendering the valve free of self generated particles.

  20. Flight control actuation system

    NASA Technical Reports Server (NTRS)

    Wingett, Paul T. (Inventor); Gaines, Louie T. (Inventor); Evans, Paul S. (Inventor); Kern, James I. (Inventor)

    2004-01-01

    A flight control actuation system comprises a controller, electromechanical actuator and a pneumatic actuator. During normal operation, only the electromechanical actuator is needed to operate a flight control surface. When the electromechanical actuator load level exceeds 40 amps positive, the controller activates the pneumatic actuator to offset electromechanical actuator loads to assist the manipulation of flight control surfaces. The assistance from the pneumatic load assist actuator enables the use of an electromechanical actuator that is smaller in size and mass, requires less power, needs less cooling processes, achieves high output forces and adapts to electrical current variations. The flight control actuation system is adapted for aircraft, spacecraft, missiles, and other flight vehicles, especially flight vehicles that are large in size and travel at high velocities.

  1. Nanotube Nano-actuators

    NASA Astrophysics Data System (ADS)

    Jennifer, Sippel; Arnason, Steve; Baughman, Ray; Rinzler, Andrew

    2002-03-01

    In 1999 it was found that a thin sheet of single wall carbon nanotubes (buckypaper) can act as an electromechanical transducer (an actuator), converting an applied voltage into a dimensional change, with the potential to do work.[1] The mechanism proposed for the effect is quite fundamental, relying on modification of the nearest neighbor carbon-carbon distance due to charge injected into the nanotube pi-orbital system. Because the experiment relied on buckypaper, which possesses nanoscale pores (where gas generation might also account for dimensional changes), as well as creep (where ropes sliding against one another make it difficult to determine the magnitude of the effect in the fundamental unit), the demonstration was less than ideal. Using an atomic force microscope for detection, we have now performed corresponding measurements on individual ropes of nanotubes tethered across micromachined trenches in silicon substrates. The experiment and results will be described. 1. R. H. Baughman, C. X. Cui, A. A. Zakhidov, Z. Iqbal, J. N. Barisci, G. M. Spinks, G. G. Wallace, A. Mazzoldi, D DeRossi, A. G. Rinzler, O. Jaschinski, S. Roth, M. Kertesz, Science, 284, 1340 (1999).

  2. Dielectric Elastomer Actuated Systems and Methods

    NASA Technical Reports Server (NTRS)

    Dubowsky, Steven (Inventor); Hafez, Moustapha (Inventor); Lichter, Matthew (Inventor); Weiss, Peter (Inventor); Wingert, Andreas (Inventor)

    2008-01-01

    The system of the present invention includes an actuator having at least two electrodes, an elastomeric dielectric film disposed between the two electrodes, and a frame attached to the elastomeric dielectric film. The frame provides a linear actuation force characteristic over a displacement range. The displacement range is preferably the stroke of the actuator. The displacement range can be about 5 mm and greater. Further, the frame can include a plurality of configurations, for example, at least a rigid members coupled to a flexible member wherein the frame provides an elastic restoring force. In preferred embodiments, the rigid member can be, but is not limited to, curved beams, parallel beams, rods and plates. In a preferred embodiment the actuator can further include a passive element disposed between two flexible members such as, for example, links to tune a stiffness characteristic of the actuator. The passive element can be a bi-stable element. Further, the actuator can include a plurality of layers of the elastomeric dielectric film integrated into the frame. The elastomeric film can be made of different materials such as, for example, acrylic, silicone and latex.

  3. 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.

  4. Superconducting linear actuator

    NASA Technical Reports Server (NTRS)

    Johnson, Bruce; Hockney, Richard

    1993-01-01

    Special actuators are needed to control the orientation of large structures in space-based precision pointing systems. Electromagnetic actuators that presently exist are too large in size and their bandwidth is too low. Hydraulic fluid actuation also presents problems for many space-based applications. Hydraulic oil can escape in space and contaminate the environment around the spacecraft. A research study was performed that selected an electrically-powered linear actuator that can be used to control the orientation of a large pointed structure. This research surveyed available products, analyzed the capabilities of conventional linear actuators, and designed a first-cut candidate superconducting linear actuator. The study first examined theoretical capabilities of electrical actuators and determined their problems with respect to the application and then determined if any presently available actuators or any modifications to available actuator designs would meet the required performance. The best actuator was then selected based on available design, modified design, or new design for this application. The last task was to proceed with a conceptual design. No commercially-available linear actuator or modification capable of meeting the specifications was found. A conventional moving-coil dc linear actuator would meet the specification, but the back-iron for this actuator would weigh approximately 12,000 lbs. A superconducting field coil, however, eliminates the need for back iron, resulting in an actuator weight of approximately 1000 lbs.

  5. 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. PMID:24751475

  6. Rod examination gauge

    SciTech Connect

    Bacvinskas, W.S.; Bayer, J.E.; Davis, W.W.; Fodor, G.; Kikta, T.J.; Matchett, R.L.; Nilsen, R.J.; Wilczynski, R.

    1991-12-31

    The present invention is directed to a semi-automatic rod examination gauge for performing a large number of exacting measurements on radioactive fuel rods. The rod examination gauge performs various measurements underwater with remote controlled machinery of high reliability. The rod examination gauge includes instruments and a closed circuit television camera for measuring fuel rod length, free hanging bow measurement, diameter measurement, oxide thickness measurement, cladding defect examination, rod ovality measurement, wear mark depth and volume measurement, as well as visual examination. A control system is provided including a programmable logic controller and a computer for providing a programmed sequence of operations for the rod examination and collection of data.

  7. FUEL ROD ASSEMBLY

    DOEpatents

    Hutter, E.

    1959-09-01

    A cluster of nuclear fuel rods aod a tubular casing through which a coolant flows in heat-change contact with the ruel rods are described. The casting is of trefoil section and carries the fuel rods, each of which has two fin engaging the serrated fins of the other two fuel rods, whereby the fuel rods are held in the casing and are interlocked against relative longitudinal movement.

  8. Micromachined electrostatic vertical actuator

    DOEpatents

    Lee, Abraham P.; Sommargren, Gary E.; McConaghy, Charles F.; Krulevitch, Peter A.

    1999-10-19

    A micromachined vertical actuator utilizing a levitational force, such as in electrostatic comb drives, provides vertical actuation that is relatively linear in actuation for control, and can be readily combined with parallel plate capacitive position sensing for position control. The micromachined electrostatic vertical actuator provides accurate movement in the sub-micron to micron ranges which is desirable in the phase modulation instrument, such as optical phase shifting. For example, compact, inexpensive, and position controllable micromirrors utilizing an electrostatic vertical actuator can replace the large, expensive, and difficult-to-maintain piezoelectric actuators. A thirty pound piezoelectric actuator with corner cube reflectors, as utilized in a phase shifting diffraction interferometer can be replaced with a micromirror and a lens. For any very precise and small amplitudes of motion` micromachined electrostatic actuation may be used because it is the most compact in size, with low power consumption and has more straightforward sensing and control options.

  9. Electromagnetic rotational actuation.

    SciTech Connect

    Hogan, Alexander Lee

    2010-08-01

    There are many applications that need a meso-scale rotational actuator. These applications have been left by the wayside because of the lack of actuation at this scale. Sandia National Laboratories has many unique fabrication technologies that could be used to create an electromagnetic actuator at this scale. There are also many designs to be explored. In this internship exploration of the designs and fabrications technologies to find an inexpensive design that can be used for prototyping the electromagnetic rotational actuator.

  10. AMSD Cryo Actuator Testing

    NASA Technical Reports Server (NTRS)

    Mullette, Mark; Matthews, Gary; Russell, Kevin (Technical Monitor)

    2002-01-01

    The actuator technology required for AMSD and subsequently NGST are critical in the successful development for future cryogenic systems. Kodak has undertaken an extensive test plan to determine the performance of the force actuators developed under the AMSD program. These actuators are currently in testing at MSFC and are expected to finish this test cycle in early June 2002.

  11. Subminiature hydraulic actuator

    NASA Technical Reports Server (NTRS)

    Sevart, F. D.

    1978-01-01

    Subminiature, single-vane rotary actuator for wind-tunnel test-model control-surface actuation systems presents severe torque and system band-pass requirements with stringent space and weight limitations. Actuator has very low leakage of fluid from one side to other, permitting use in precision position servo-systems.

  12. Dual drive actuators

    NASA Technical Reports Server (NTRS)

    Packard, D. T.

    1982-01-01

    A new class of electromechanical actuators is described. These dual drive actuators were developed for the NASA-JPL Galileo Spacecraft. The dual drive actuators are fully redundant and therefore have high inherent reliability. They can be used for a variety of tasks, and they can be fabricated quickly and economically.

  13. Omnidirectional Actuator Handle

    NASA Technical Reports Server (NTRS)

    Moetteli, John B.

    1995-01-01

    Proposed actuator handle comprises two normally concentric rings, cables, and pulleys arranged such that relative displacement of rings from concentricity results in pulling of cable and consequent actuation of associated mechanism. Unlike conventional actuator handles like levers on farm implements, actuated from one or two directions only, proposed handle reached from almost any direction and actuated by pulling or pushing inner ring in any direction with respect to outer ring. Flanges installed on inner ring to cover gap between inner ring and housing to prevent clothing from being caught.

  14. Bimorphic polymeric photomechanical actuator

    NASA Technical Reports Server (NTRS)

    Sarkisov, Sergey S. (Inventor); Curley, Michael J. (Inventor); Adamovsky, Grigory (Inventor); Sarkisov, Jr., Sergey S. (Inventor); Fields, Aisha B. (Inventor)

    2006-01-01

    A bimorphic polymeric photomechanical actuator, in one embodiment using polyvinylidene fluoride (PVDF) as a photosensitive body, transmitting light over fiber optic cables, and controlling the shape and pulse duration of the light pulse to control movement of the actuator. Multiple light beams are utilized to generate different ranges of motion for the actuator from a single photomechanical body and alternative designs use multiple light beams and multiple photomechanical bodies to provide controlled movement. Actuator movement using one or more ranges of motion is utilized to control motion to position an actuating element in three dimensional space.

  15. Flexible sliding seal

    NASA Technical Reports Server (NTRS)

    Wallenhorst, E. L.

    1980-01-01

    Circular seal both slides and flexes to accomodate relative motion between two sealed members. Originally developed for Space Shuttle orbiter, it contains sliding seal to accommodate engine gimbaling and flexible seal that absorbs forward motion at high thrust of engine heat shield relative to airframe. Other possible applications are in support structures of heavy machinery and vehicle engines. Flexible sliding seal is ring about 7 feet in diameter and can withstand temperatures up to 1,600 F.

  16. Smart missile fins with active spoiler using a piezoelectric actuator

    NASA Astrophysics Data System (ADS)

    Kim, Seung J.; Yun, Chul Y.; Moon, Seong H.; Hwang, Sung; Jung, Sung-Nam

    2002-07-01

    In this work, smart missile fins with trailing-edge-mounted retractable wedge are investigated. The wedge stretches back or forth in the chordwise direction in a means to reduce the applied pitching moment acting on the missile fins. An actuator system, which is composed of a one-way clutch bearing, driving shaft with thread and sliding nut and a piezo-bimorph beam, has been built and tested to verify the concept of the actuator. This actuator is designed to translate the rotational motion of the shaft into the linear motion of the sliding nut to generate a desired stroke. When a voltage signal is applied at a given frequency to the piezo-element, it will bend up and down. This bending action induces an angular input to the shaft, which is then rectified with the clutch bearing to the rotational output of the shaft. Preliminary tests showed that the proposed actuator system can be very effective in generating large stroke output with relatively small voltage inputs: Nearly 19mm of actuator displacement was obtained under an input voltage of 75 Vrms at a frequency level of 700 Hz. A series of experimental tests as well as CFD calculations for missile aerodynamics have been performed to investigate the effectiveness of the actuator.

  17. 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.

  18. 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.

  19. Herbaceous Ornamental Plants. 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 commercially important herbaceous ornamental plants. Included in the script are narrations for use with a total of 338 slides illustrating 150 different plants. Generally, two slides are used to illustrate each plant: one slide shows…

  20. Electropneumatic actuator, phase 1

    NASA Astrophysics Data System (ADS)

    Bloomfield, D. P.

    1989-10-01

    The program demonstrated the feasibility of an electropneumatic actuator which can be used in manufacturing applications. The electropneumatic actuator, an alternative to the electric, hydraulic, and pneumatic actuators used in industry, consists of an electrochemical compressor, a power supply, and an actuator. The electrochemical compressor working fluid is hydrogen and a solvent such as water or ammonia. The compressor has no moving parts and runs on low voltage DC. The actuator is a conventional, commercially available unit. Researchers designed, constructed, and tested the electrochemical compressor in conjunction with the actuator, power supply, and computerized control. The one inch actuator can lift a fifty pound weight a distance of ten inches in about 1.5 minutes. The electrochemically powered system is capable of driving its loaded actuator to a prescribed location at a controlled rate. A defined set of design changes will combine the compressor and actuator in the same housing, and will develop two orders of magnitude increased actuator speed at the same or higher force levels.

  1. Piston rod seal

    DOEpatents

    Lindskoug, Stefan

    1984-01-01

    In a piston rod seal of the type comprising a gland through which the piston rod is passed the piston is provided with a sleeve surrounding the piston rod and extending axially so as to axially partly overlap the gland when the piston is in its bottom dead center position.

  2. 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...

  3. Slide Classification and Cataloging.

    ERIC Educational Resources Information Center

    Clawson, Catherine R.; Ronkowski, Charles A.

    1981-01-01

    Follows up an August 1978 article on the cataloging of slides using color photocopying, and presents unsolicited reactions to that article from librarians who were interested in the slide system developed for use in the C-E Refractories Research and Development Library. Twelve references are listed. (FM)

  4. UNDERSTANDING THE SLIDE RULE.

    ERIC Educational Resources Information Center

    JOHNSON, RONALD E.; AND OTHERS

    A BOOKLET DESIGNED FOR ELEMENTARY SCHOOL STUDENTS TO BE USED INDEPENDENTLY FROM AND IN ADDITION TO THE REGULAR CLASSROOM CURRICULUM IN MATHEMATICS IS GIVEN. THE FIFTH- OR SIXTH-GRADE STUDENT IS PRESENTED WITH A DISCUSSION OF THE APPLICATIONS OF THE SLIDE RULE AND WITH A BACKGROUND REVIEW OF NECESSARY CONCEPTS. THE CONCEPTS OF THE SLIDE RULE ARE…

  5. Actuation of shape-memory colloidal fibres of Janus ellipsoids

    NASA Astrophysics Data System (ADS)

    Shah, Aayush A.; Schultz, Benjamin; Zhang, Wenjia; Glotzer, Sharon C.; Solomon, Michael J.

    2015-01-01

    Many natural micrometre-scale assemblies can be actuated to control their optical, transport and mechanical properties, yet such functionality is lacking in colloidal structures synthesized thus far. Here, we show with experiments and computer simulations that Janus ellipsoids can self-assemble into self-limiting one-dimensional fibres with shape-memory properties, and that the fibrillar assemblies can be actuated on application of an external alternating-current electric field. Actuation of the fibres occurs through a sliding mechanism that permits the rapid and reversible elongation and contraction of the Janus-ellipsoid chains by ~36% and that on long timescales leads to the generation of long, uniform self-assembled fibres. Colloidal-scale actuation might be useful in microrobotics and in applications of shape-memory materials.

  6. MEMS fluidic actuator

    DOEpatents

    Kholwadwala, Deepesh K.; Johnston, Gabriel A.; Rohrer, Brandon R.; Galambos, Paul C.; Okandan, Murat

    2007-07-24

    The present invention comprises a novel, lightweight, massively parallel device comprising microelectromechanical (MEMS) fluidic actuators, to reconfigure the profile, of a surface. Each microfluidic actuator comprises an independent bladder that can act as both a sensor and an actuator. A MEMS sensor, and a MEMS valve within each microfluidic actuator, operate cooperatively to monitor the fluid within each bladder, and regulate the flow of the fluid entering and exiting each bladder. When adjacently spaced in a array, microfluidic actuators can create arbitrary surface profiles in response to a change in the operating environment of the surface. In an embodiment of the invention, the profile of an airfoil is controlled by independent extension and contraction of a plurality of actuators, that operate to displace a compliant cover.

  7. CONTROL ROD DRIVE

    DOEpatents

    Chapellier, R.A.; Rogers, I.

    1961-06-27

    Accurate and controlled drive for the control rod is from an electric motor. A hydraulic arrangement is provided to balance a piston against which a control rod is urged by the application of fluid pressure. The electric motor drive of the control rod for normal operation is made through the aforementioned piston. In the event scramming is required, the fluid pressure urging the control rod against the piston is relieved and an opposite fluid pressure is applied. The lack of mechanical connection between the electric motor and control rod facilitates the scramming operation.

  8. CRUCIFORM CONTROL ROD JOINT

    DOEpatents

    Thorp, A.G. II

    1962-08-01

    An invention is described which relates to nuclear reactor control rod components and more particularly to a joint between cruciform control rod members and cruciform control rod follower members. In one embodiment this invention provides interfitting crossed arms at adjacent ends of a control rod and its follower in abutting relation. This holds the members against relative opposite longitudinal movement while a compression member keys the arms against relative opposite rotation around a common axis. Means are also provided for centering the control rod and its follower on a common axis and for selectively releasing the control rod from its follower for the insertion of a replacement of the control rod and reuse of the follower. (AEC)

  9. Comprehensive piezoceramic actuator review

    NASA Astrophysics Data System (ADS)

    Taylor, Chris J.; Washington, Gregory N.

    2002-07-01

    Piezoceramic actuation has become an area of increased interest in the past ten years. Having been used for many years as sensors in such applications as pressure transducers and smoke detectors, piezoceramics are now being used as prime movers in fuel injectors and valve lifters. In an effort to aid the engineering community, this paper will conduct a comprehensive review of several piezoceramic actuators. Classical design parameters will be derived for each actuator such as blocked force and free stroke. In addition, more esoteric entities such as mechanical efficiency and energy density will also be derived. The result will be design metrics of popular piezoceramic actuators containing vital design equations, validated with empirical data. Of the many different configurations of piezoceramic actuators, this paper will investigate the bimorph and unimorph bender. These actuator types are finding increased use in semi-active structural damping, energy harvesting and vibration control. The work in this paper will show experimental verification of various actuator types as well as theoretical derivations. In addition to unimorphs, bimorphs and stack actuators a novel type of unimorph bender, the THUNDER actuator (developed and licensed by NASA) will be included in the review.

  10. Nuclear reactor shutdown control rod assembly

    DOEpatents

    Bilibin, Konstantin

    1988-01-01

    A temperature responsive, self-actuated nuclear reactor shutdown control rod assembly 10. The upper end 18 of a lower drive line 17 fits within the lower end of an upper drive line 12. The lower end (not shown) of the lower drive line 17 is connected to a neutron absorber. During normal temperature conditions the lower drive line 17 is supported by detent means 22,26. When an overtemperature condition occurs thermal actuation means 34 urges ring 26 upwardly sufficiently to allow balls 22 to move radially outwardly thereby allowing lower drive line 17 to move downwardly toward the core of the nuclear reactor resulting in automatic reduction of the reactor powder.

  11. Design for slides.

    PubMed

    Johns, M

    1995-09-01

    The basic principles of design for projection slides are discussed, with particular reference to the impact of the personal computer and commercial presentation software on the material that is destined to end up on the screen at meetings and in seminar rooms. While modern software can be a boon to the presenter, allowing simple creation of slides, it can also encourage some of the worst excesses. The keynote of the design of slides for educational purposes should be simplicity, and ways of achieving simple but effective results are described. PMID:8550965

  12. Remote control thermal actuator

    NASA Technical Reports Server (NTRS)

    Englund, D. R.; Harrigill, W. T.; Krsek, A.

    1969-01-01

    Thermal actuator makes precise changes in the position of one object with respect to another. Expansion of metal tubes located in the actuator changes the position of the mounting block. Capacitance probe measures the change in position of the block relative to the fixed target plate.

  13. Self-actuated device

    DOEpatents

    Hecht, Samuel L.

    1984-01-01

    A self-actuated device, of particular use as a valve or an orifice for nuclear reactor fuel and blanket assemblies, in which a gas produced by a neutron induced nuclear reaction gradually accumulates as a function of neutron fluence. The gas pressure increase occasioned by such accumulation of gas is used to actuate the device.

  14. Control surface actuator

    NASA Technical Reports Server (NTRS)

    Seidel, Gerhard E. (Inventor)

    1988-01-01

    A device which actuates aircraft control surfaces is disclosed. The actuator is disposed entirely within the control surface structure. This allows the gap between the wing structural box and the control surface to be reduced. Reducing the size of the gap is especially desirable for wings with high aspect ratio, wherein the volume of the structural box is at a premium.

  15. 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)

  16. Fast electrochemical actuator

    NASA Astrophysics Data System (ADS)

    Uvarov, I. V.; Postnikov, A. V.; Svetovoy, V. B.

    2016-03-01

    Lack of fast and strong microactuators is a well-recognized problem in MEMS community. Electrochemical actuators can develop high pressure but they are notoriously slow. Water electrolysis produced by short voltage pulses of alternating polarity can overcome the problem of slow gas termination. Here we demonstrate an actuation regime, for which the gas pressure is relaxed just for 10 μs or so. The actuator consists of a microchamber filled with the electrolyte and covered with a flexible membrane. The membrane bends outward when the pressure in the chamber increases. Fast termination of gas and high pressure developed in the chamber are related to a high density of nanobubbles in the chamber. The physical processes happening in the chamber are discussed so as problems that have to be resolved for practical applications of this actuation regime. The actuator can be used as a driving engine for microfluidics.

  17. 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.

  18. 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. PMID:11381856

  19. 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…

  20. 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…

  1. 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…

  2. 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.

  3. CONTROL ROD DRIVE

    DOEpatents

    Chapellier, R.A.

    1960-05-24

    BS>A drive mechanism was invented for the control rod of a nuclear reactor. Power is provided by an electric motor and an outside source of fluid pressure is utilized in conjunction with the fluid pressure within the reactor to balance the loadings on the motor. The force exerted on the drive mechanism in the direction of scramming the rod is derived from the reactor fluid pressure so that failure of the outside pressure source will cause prompt scramming of the rod.

  4. Pull rod assembly

    DOEpatents

    Cioletti, O.C.

    1988-04-21

    A pull rod assembly comprising a pull rod having three peripheral grooves, a piston device including an adaptor ring and a seal ring, said piston device being mounted on the pull rod by a split ring retainer situated in one groove and extending into an interior groove in the adaptor and a resilient split ring retained in another groove and positioned to engage the piston device and to retain the seal on its adaptor.

  5. 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.

  6. Design and analysis of a new AUV's sliding control system based on dynamic boundary layer

    NASA Astrophysics Data System (ADS)

    Gao, Fudong; Pan, Cunyun; Han, Yanyan

    2013-01-01

    The new AUV driven by multi-vectored thrusters not only has unique kinematic characteristics during the actual cruise but also exists uncertain factors such as hydrodynamic coefficients perturbation and unknown interference of tail fluid, which bring difficult to the stability of the AUV's control system. In order to solve the nonlinear term and unmodeled dynamics existing in the new AUV's attitude control and the disturbances caused by the external marine environment, a second-order sliding mode controller with double-loop structure that considering the dynamic characteristics of the rudder actuators is designed, which improves the robustness of the system and avoids the control failure caused by the problem that the design theory of the sliding mode controller does not match with the actual application conditions. In order to avoid the loss of the sliding mode caused by the amplitude and rate constraints of the rudder actuator in the new AUV's attitude control, the dynamic boundary layer method is used to adjust the sliding boundary layer thickness so as to obtain the best anti-chattering effects. Then the impacts of system parameters, rudder actuator's constraints and boundary layer on the sliding mode controller are computed and analyzed to verify the effectiveness and robustness of the sliding mode controller based on dynamic boundary layer. The computational results show that the original divergent second-order sliding mode controller can still effectively implement the AUV's attitude control through dynamically adjusting the sliding boundary layer thickness. The dynamic boundary layer method ensures the stability of the system and does not exceed the amplitude constraint of the rudder actuator, which provides a theoretical guidance and technical support for the control system design of the new AUV in real complex sea conditions.

  7. Bioinspired Smart Actuator Based on Graphene Oxide-Polymer Hybrid Hydrogels.

    PubMed

    Wang, Tao; Huang, Jiahe; Yang, Yiqing; Zhang, Enzhong; Sun, Weixiang; Tong, Zhen

    2015-10-28

    Rapid response and strong mechanical properties are desired for smart materials used in soft actuators. A bioinspired hybrid hydrogel actuator was designed and prepared by series combination of three trunks of tough polymer-clay hydrogels to accomplish the comprehensive actuation of "extension-grasp-retraction" like a fishing rod. The hydrogels with thermo-creep and thermo-shrinking features were successively irradiated by near-infrared (NIR) to execute extension and retraction, respectively. The GO in the hydrogels absorbed the NIR energy and transformed it into thermo-energy rapidly and effectively. The hydrogel with adhesion or magnetic force was adopted as the "hook" of the hybrid hydrogel actuator for grasping object. The hook of the hybrid hydrogel actuator was replaceable according to applications, even with functional materials other than hydrogels. This study provides an innovative concept to explore new soft actuators through combining response hydrogels and programming the same stimulus. PMID:26448049

  8. Electro-Mechanical Actuators

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The electro-mechanical actuator, a new electronics technology, is an electronic system that provides the force needed to move valves that control the flow of propellant to the engine. It is proving to be advantageous for the main propulsion system plarned for a second generation reusable launch vehicle. Hydraulic actuators have been used successfully in rocket propulsion systems. However, they can leak when high pressure is exerted on such a fluid-filled hydraulic system. Also, hydraulic systems require significant maintenance and support equipment. The electro-mechanical actuator is proving to be low maintenance and the system weighs less than a hydraulic system. The electronic controller is a separate unit powering the actuator. Each actuator has its own control box. If a problem is detected, it can be replaced by simply removing one defective unit. The hydraulic systems must sustain significant hydraulic pressures in a rocket engine regardless of demand. The electro-mechanical actuator utilizes power only when needed. A goal of the Second Generation Reusable Launch Vehicle Program is to substantially improve safety and reliability while reducing the high cost of space travel. The electro-mechanical actuator was developed by the Propulsion Projects Office of the Second Generation Reusable Launch Vehicle Program at the Marshall Space Flight Center.

  9. Cryogenic Piezoelectric Actuator

    NASA Technical Reports Server (NTRS)

    Jiang, Xiaoning; Cook, William B.; Hackenberger, Wesley S.

    2009-01-01

    In this paper, PMN-PT single crystal piezoelectric stack actuators and flextensional actuators were designed, prototyped and characterized for space optics applications. Single crystal stack actuators with footprint of 10 mm x10 mm and the height of 50 mm were assembled using 10 mm x10mm x0.15mm PMN-PT plates. These actuators showed stroke > 65 - 85 microns at 150 V at room temperature, and > 30 microns stroke at 77 K. Flextensional actuators with dimension of 10mm x 5 mm x 7.6 mm showed stroke of >50 microns at room temperature at driving voltage of 150 V. A flextensional stack actuator with dimension of 10 mm x 5 mm x 47 mm showed stroke of approx. 285 microns at 150 V at room temperature and > 100 microns at 77K under driving of 150 V should be expected. The large cryogenic stroke and high precision of these actuators are promising for cryogenic optics applications.

  10. MEMS Actuated Deformable Mirror

    SciTech Connect

    Papavasiliou, A; Olivier, S; Barbee, T; Walton, C; Cohn, M

    2005-11-10

    This ongoing work concerns the creation of a deformable mirror by the integration of MEMS actuators with Nanolaminate foils through metal compression boning. These mirrors will use the advantages of these disparate technologies to achieve dense actuation of a high-quality, continuous mirror surface. They will enable advanced adaptive optics systems in large terrestrial telescopes. While MEMS actuators provide very dense actuation with high precision they can not provide large forces typically necessary to deform conventional mirror surfaces. Nanolaminate foils can be fabricated with very high surface quality while their extraordinary mechanical properties enable very thin, flexible foils to survive the rigors of fabrication. Precise metal compression bonding allows the attachment of the fragile MEMS actuators to the thin nanolaminate foils without creating distortions at the bond sites. This paper will describe work in four major areas: (1) modeling and design, (2) bonding development, (3) nanolaminate foil development, (4) producing a prototype. A first-principles analytical model was created and used to determine the design parameters. A method of bonding was determined that is both strong, and minimizes the localized deformation or print through. Work has also been done to produce nanolaminate foils that are sufficiently thin, flexible and flat to be deformed by the MEMS actuators. Finally a prototype was produced by bonding thin, flexible nanolaminate foils to commercially available MEMS actuators.

  11. Aeroelastic control of flutter using trailing edge control surfaces powered by piezoelectric actuators

    NASA Astrophysics Data System (ADS)

    Ardelean, Emil Valentin

    Flutter is a rather spectacular phenomenon of aeroelastic instability that affects lifting and control surfaces, yet can also lead to catastrophic consequences for the aircraft. The idea of controlling flutter by using the same energy that causes it, namely airflow energy, through changing the aerodynamics in a controlled manner is not new. In the case of fixed wings, the use of trailing edge control surfaces (flaps) is an extremely effective method to alter the aerodynamics. This research presents the development of an actuation system for trailing edge control surfaces (flaps) used for aeroelastic flutter control of a typical section wing model. In order to be effective for aeroelastic control of flutter, flap deflection of +/-5-6° with adequate bandwidth (up to 25--30 Hz) is required. Classical solutions for flap actuation do not have the capabilities required for this task. Therefore actuation systems using active materials became the focus of this investigation. A new piezoelectric actuator (V-Stack Piezoelectric Actuator) was developed. This actuator meets the requirements for trailing edge flap actuation in both stroke and force over the bandwidth of interest. It is compact, simple, sturdy, and leverages stroke geometrically with minimum force penalties, while displaying linearity over a wide range of stroke. Integration of the actuator inside an existing structure requires minimal modifications of the structure. The shape of the actuator makes it very suitable for trailing edge flap actuation, eliminating the need for a push rod. The actuation solution presented here stands out because of its simplicity, compactness, small mass (compared to that of the actuated structure) and high reliability. Although the actuator was designed for flap actuation, other applications can also benefit from its capabilities. In order to demonstrate the actuation concept, a typical section prototype was constructed and tested experimentally in the wind tunnel at Duke

  12. Tensor product model transformation based decoupled terminal sliding mode control

    NASA Astrophysics Data System (ADS)

    Zhao, Guoliang; Li, Hongxing; Song, Zhankui

    2016-06-01

    The main objective of this paper is to propose a tensor product model transformation based decoupled terminal sliding mode controller design methodology. The methodology is divided into two steps. In the first step, tensor product model transformation is applied to the single-input-multi-output system and a parameter-varying weighted linear time-invariant system is obtained. Then, decoupled terminal sliding mode controller is designed based on the linear time-invariant systems. The main novelty of this paper is that the nonsingular terminal sliding mode control design is based on a numerical model rather than an analytical one. Finally, simulations are tested on cart-pole system and translational oscillations with a rotational actuator system.

  13. FUEL ROD CLUSTERS

    DOEpatents

    Schultz, A.B.

    1959-08-01

    A cluster of nuclear fuel rods and a tubular casing therefor through which a coolant flows in heat-exchange contact with the fuel rods is described. The fuel rcds are held in the casing by virtue of the compressive force exerted between longitudinal ribs of the fuel rcds and internal ribs of the casing or the internal surfaces thereof.

  14. Rod Photoreceptors Detect Rapid Flicker

    ERIC Educational Resources Information Center

    Conner, J. D.; MacLeod, Donald I. A.

    1977-01-01

    Rod-isolation techniques show that light-adapted human rods detect flicker frequencies as high as 28 hertz, and that the function relating rod critical flicker frequency to stimulus intensity contains two distinct branches. (MLH)

  15. Magnetically Actuated Seal

    NASA Technical Reports Server (NTRS)

    Pinera, Alex

    2013-01-01

    This invention is a magnetically actuated seal in which either a single electromagnet, or multiple electromagnets, are used to control the seal's position. This system can either be an open/ close type of system or an actively controlled system.

  16. Rotary Series Elastic Actuator

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Mehling, Joshua S. (Inventor); Parsons, Adam H. (Inventor); Griffith, Bryan Kristian (Inventor); Radford, Nicolaus A. (Inventor); Permenter, Frank Noble (Inventor); Davis, Donald R. (Inventor); Ambrose, Robert O. (Inventor); Junkin, Lucien Q. (Inventor)

    2013-01-01

    A rotary actuator assembly is provided for actuation of an upper arm assembly for a dexterous humanoid robot. The upper arm assembly for the humanoid robot includes a plurality of arm support frames each defining an axis. A plurality of rotary actuator assemblies are each mounted to one of the plurality of arm support frames about the respective axes. Each rotary actuator assembly includes a motor mounted about the respective axis, a gear drive rotatably connected to the motor, and a torsion spring. The torsion spring has a spring input that is rotatably connected to an output of the gear drive and a spring output that is connected to an output for the joint.

  17. Rotary series elastic actuator

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Mehling, Joshua S. (Inventor); Parsons, Adam H. (Inventor); Griffith, Bryan Kristian (Inventor); Radford, Nicolaus A. (Inventor); Permenter, Frank Noble (Inventor); Davis, Donald R. (Inventor); Ambrose, Robert O. (Inventor); Junkin, Lucien Q. (Inventor)

    2012-01-01

    A rotary actuator assembly is provided for actuation of an upper arm assembly for a dexterous humanoid robot. The upper arm assembly for the humanoid robot includes a plurality of arm support frames each defining an axis. A plurality of rotary actuator assemblies are each mounted to one of the plurality of arm support frames about the respective axes. Each rotary actuator assembly includes a motor mounted about the respective axis, a gear drive rotatably connected to the motor, and a torsion spring. The torsion spring has a spring input that is rotatably connected to an output of the gear drive and a spring output that is connected to an output for the joint.

  18. Muscle Motion Solenoid Actuator

    NASA Astrophysics Data System (ADS)

    Obata, Shuji

    It is one of our dreams to mechanically recover the lost body for damaged humans. Realistic humanoid robots composed of such machines require muscle motion actuators controlled by all pulling actions. Particularly, antagonistic pairs of bi-articular muscles are very important in animal's motions. A system of actuators is proposed using the electromagnetic force of the solenoids with the abilities of the stroke length over 10 cm and the strength about 20 N, which are needed to move the real human arm. The devised actuators are based on developments of recent modern electro-magnetic materials, where old time materials can not give such possibility. Composite actuators are controlled by a high ability computer and software making genuine motions.

  19. Linear Proof Mass Actuator

    NASA Technical Reports Server (NTRS)

    Holloway, Sidney E., III

    1994-01-01

    This paper describes the mechanical design, analysis, fabrication, testing, and lessons learned by developing a uniquely designed spaceflight-like actuator. The linear proof mass actuator (LPMA) was designed to attach to both a large space structure and a ground test model without modification. Previous designs lacked the power to perform in a terrestrial environment while other designs failed to produce the desired accelerations or frequency range for spaceflight applications. Thus, the design for a unique actuator was conceived and developed at NASA Langley Research Center. The basic design consists of four large mechanical parts (mass, upper housing, lower housing, and center support) and numerous smaller supporting components including an accelerometer, encoder, and four drive motors. Fabrication personnel were included early in the design phase of the LPMA as part of an integrated manufacturing process to alleviate potential difficulties in machining an already challenging design. Operating testing of the LPMA demonstrated that the actuator is capable of various types of load functions.

  20. Linear Proof Mass Actuator

    NASA Technical Reports Server (NTRS)

    Holloway, S. E., III

    1995-01-01

    This paper describes the mechanical design, analysis, fabrication, testing, and lessons learned by developing a uniquely designed spaceflight-like actuator. The Linear Proof Mass Actuator (LPMA) was designed to attach to both a large space structure and a ground test model without modification. Previous designs lacked the power to perform in a terrestrial environment while other designs failed to produce the desired accelerations or frequency range for spaceflight applications. Thus, the design for a unique actuator was conceived and developed at NASA Langley Research Center. The basic design consists of four large mechanical parts (Mass, Upper Housing, Lower Housing, and Center Support) and numerous smaller supporting components including an accelerometer, encoder, and four drive motors. Fabrication personnel were included early in the design phase of the LPMA as part of an integrated manufacturing process to alleviate potential difficulties in machining an already challenging design. Operational testing of the LPMA demonstrated that the actuator is capable of various types of load functions.

  1. Laser Initiated Actuator study

    SciTech Connect

    Watson, B.

    1991-06-27

    The program task was to design and study a laser initiated actuator. The design of the actuator is described, it being comprised of the fiber and body subassemblies. The energy source for all experiments was a Spectra Diode 2200-H2 laser diode. The diode is directly coupled to a 100 micron core, 0.3 numerical aperture fiber optic terminated with an SMA connector. The successful testing results are described and recommendations are made.

  2. Inertial Linear Actuators

    NASA Technical Reports Server (NTRS)

    Laughlin, Darren

    1995-01-01

    Inertial linear actuators developed to suppress residual accelerations of nominally stationary or steadily moving platforms. Function like long-stroke version of voice coil in conventional loudspeaker, with superimposed linear variable-differential transformer. Basic concept also applicable to suppression of vibrations of terrestrial platforms. For example, laboratory table equipped with such actuators plus suitable vibration sensors and control circuits made to vibrate much less in presence of seismic, vehicular, and other environmental vibrational disturbances.

  3. Combustion powered linear actuator

    DOEpatents

    Fischer, Gary J.

    2007-09-04

    The present invention provides robotic vehicles having wheeled and hopping mobilities that are capable of traversing (e.g. by hopping over) obstacles that are large in size relative to the robot and, are capable of operation in unpredictable terrain over long range. The present invention further provides combustion powered linear actuators, which can include latching mechanisms to facilitate pressurized fueling of the actuators, as can be used to provide wheeled vehicles with a hopping mobility.

  4. Tendon Driven Finger Actuation System

    NASA Technical Reports Server (NTRS)

    Ihrke, Chris A. (Inventor); Reich, David M. (Inventor); Bridgwater, Lyndon (Inventor); Linn, Douglas Martin (Inventor); Askew, Scott R. (Inventor); Diftler, Myron A. (Inventor); Platt, Robert (Inventor); Hargrave, Brian (Inventor); Valvo, Michael C. (Inventor); Abdallah, Muhammad E. (Inventor); Permenter, Frank Noble (Inventor); Mehling, Joshua S. (Inventor)

    2013-01-01

    A humanoid robot includes a robotic hand having at least one finger. An actuation system for the robotic finger includes an actuator assembly which is supported by the robot and is spaced apart from the finger. A tendon extends from the actuator assembly to the at least one finger and ends in a tendon terminator. The actuator assembly is operable to actuate the tendon to move the tendon terminator and, thus, the finger.

  5. Compact electrostatic comb actuator

    DOEpatents

    Rodgers, M. Steven; Burg, Michael S.; Jensen, Brian D.; Miller, Samuel L.; Barnes, Stephen M.

    2000-01-01

    A compact electrostatic comb actuator is disclosed for microelectromechanical (MEM) applications. The actuator is based upon a plurality of meshed electrostatic combs, some of which are stationary and others of which are moveable. One or more restoring springs are fabricated within an outline of the electrostatic combs (i.e. superposed with the moveable electrostatic combs) to considerably reduce the space required for the actuator. Additionally, a truss structure is provided to support the moveable electrostatic combs and prevent bending or distortion of these combs due to unbalanced electrostatic forces or external loading. The truss structure formed about the moveable electrostatic combs allows the spacing between the interdigitated fingers of the combs to be reduced to about one micron or less, thereby substantially increasing the number of active fingers which can be provided in a given area. Finally, electrostatic shields can be used in the actuator to substantially reduce unwanted electrostatic fields to further improve performance of the device. As a result, the compact electrostatic comb actuator of the present invention occupies only a fraction of the space required for conventional electrostatic comb actuators, while providing a substantial increase in the available drive force (up to one-hundred times).

  6. Hybrid electromechanical actuator and actuation system

    NASA Technical Reports Server (NTRS)

    Su, Ji (Inventor); Xu, Tian-Bing (Inventor)

    2008-01-01

    A hybrid electromechanical actuator has two different types of electromechanical elements, one that expands in a transverse direction when electric power is applied thereto and one that contracts in a transverse direction when electric power is applied thereto. The two electromechanical elements are (i) disposed in relation to one another such that the transverse directions thereof are parallel to one another, and (ii) mechanically coupled to one another at least at two opposing edges thereof. Electric power is applied simultaneously to the elements.

  7. A planar nano-positioner driven by shear piezoelectric actuators

    NASA Astrophysics Data System (ADS)

    Dong, W.; Li, H.; Du, Z.

    2016-08-01

    A planar nano-positioner driven by the shear piezoelectric actuators is proposed in this paper based on inertial sliding theory. The performance of the nano-positioner actuated by different driving signals is analyzed and discussed, e.g. the resolution and the average velocity which depend on the frequency, the amplitude and the wave form of the driving curves. Based on the proposed design, a prototype system of the nano-positioner is developed by using a capacitive sensor as the measurement device. The experiment results show that the proposed nano-positioner is capable of outputting two-dimensional motions within an area of 10 mm × 10 mm at a maximum speed of 0.25 mm/s. The corresponding resolution can be as small as 21 nm. The methodology outlined in this paper can be employed and extended to shear piezoelectric actuators involved in high precision positioning systems.

  8. Flexible low-mass robotic arm actuated by electroactive polymers

    NASA Astrophysics Data System (ADS)

    Bar-Cohen, Yoseph; Xue, T.; Shahinpoor, Mohsen; Harrison, Joycelyn S.; Smith, Joseph G.

    1998-07-01

    Miniature, lightweight, low-cost actuators that consume low- power can be used to develop unmatched robotic devices to make an impact on many technology areas. Electroactive polymers (EAP) actuators offer the potential to produce such devices and they induce relatively large bending and longitudinal actuation strains. This reported study is concentrating on the development of effective EAPs and the resultant enabling mechanisms employing their unique characteristics. Several EAP driven mechanisms, which emulate human hand, were developed including a gripper, manipulator arm and surface wiper. The manipulator arm was made of a composite rod with a lifting actuator consisting of a scrolled rope that is activated longitudinally by an electrostatic field. A gripper was made to serve as an end effector and it consisted of multiple bending EAP fingers for grabbing and holding such objects as rocks. An EAP surface wiper was developed to operate like a human finger and to demonstrate the potential to remove dust from optical and IR windows as well as solar cells. These EAP driven devices are taking advantage of the large actuation displacement of these materials for applications that have limited requirement for actuation force capability.

  9. A hybrid attitude controller consisting of electromagnetic torque rods and an active fluid ring

    NASA Astrophysics Data System (ADS)

    Nobari, Nona A.; Misra, Arun K.

    2014-01-01

    In this paper, a novel hybrid actuation system for satellite attitude stabilization is proposed along with its feasibility analysis. The system considered consists of two magnetic torque rods and one fluid ring to produce the control torque required in the direction in which magnetic torque rods cannot produce torque. A mathematical model of the system dynamics is derived first. Then a controller is developed to stabilize the attitude angles of a satellite equipped with the abovementioned set of actuators. The effect of failure of the fluid ring or a magnetic torque rod is examined as well. It is noted that the case of failure of the magnetic torque rod whose torque is along the pitch axis is the most critical, since the coupling between the roll or yaw motion and the pitch motion is quite weak. The simulation results show that the control system proposed is quite fault tolerant.

  10. Sliding mode control of magnetic suspensions for precision pointing and tracking applications

    NASA Technical Reports Server (NTRS)

    Misovec, Kathleen M.; Flynn, Frederick J.; Johnson, Bruce G.; Hedrick, J. Karl

    1991-01-01

    A recently developed nonlinear control method, sliding mode control, is examined as a means of advancing the achievable performance of space-based precision pointing and tracking systems that use nonlinear magnetic actuators. Analytic results indicate that sliding mode control improves performance compared to linear control approaches. In order to realize these performance improvements, precise knowledge of the plant is required. Additionally, the interaction of an estimating scheme and the sliding mode controller has not been fully examined in the literature. Estimation schemes were designed for use with this sliding mode controller that do not seriously degrade system performance. The authors designed and built a laboratory testbed to determine the feasibility of utilizing sliding mode control in these types of applications. Using this testbed, experimental verification of the authors' analyses is ongoing.

  11. 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…

  12. 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…

  13. Control rod driveline and grapple

    DOEpatents

    Germer, John H.

    1987-01-01

    A control rod driveline and grapple is disclosed for placement between a control rod drive and a nuclear reactor control rod containing poison for parasitic neutron absorption required for reactor shutdown. The control rod is provided with an enlarged cylindrical handle which terminates in an upwardly extending rod to provide a grapple point for the driveline. The grapple mechanism includes a tension rod which receives the upwardly extending handle and is provided with a lower annular flange. A plurality of preferably six grapple segments surround and grip the control rod handle. Each grapple rod segment grips the flange on the tension rod at an interior upper annular indentation, bears against the enlarged cylindrical handle at an intermediate annulus and captures the upwardly flaring frustum shaped handle at a lower and complementary female segment. The tension rods and grapple segments are surrounded by and encased within a cylinder. The cylinder terminates immediately and outward extending annulus at the lower portion of the grapple segments. Excursion of the tension rod relative to the encasing cylinder causes rod release at the handle by permitting the grapple segments to pivot outwardly and about the annulus on the tension rod so as to open the lower defined frustum shaped annulus and drop the rod. Relative movement between the tension rod and cylinder can occur either due to electromagnetic release of the tension rod within defined limits of travel or differential thermal expansion as between the tension rod and cylinder as where the reactor exceeds design thermal limits.

  14. Non-collinear valve actuator

    NASA Technical Reports Server (NTRS)

    Richard, James A. (Inventor)

    2012-01-01

    A non-collinear valve actuator includes a primary actuating system and a return spring system with each applying forces to a linkage system in order to regulate the flow of a quarter-turn valve. The primary actuating system and return spring system are positioned non-collinearly, which simply means the primary actuating system and return spring system are not in line with each other. By positioning the primary actuating system and return spring system in this manner, the primary actuating system can undergo a larger stroke while the return spring system experiences significantly less displacement. This allows the length of the return spring to be reduced due to the minimization of displacement thereby reducing the weight of the return spring system. By allowing the primary actuating system to undergo longer strokes, the weight of the primary actuating system may also be reduced. Accordingly, the weight of the non-collinear valve actuator is reduced.

  15. Azobenzene compound-based photomechanical actuator devices

    NASA Astrophysics Data System (ADS)

    Ye, Xianjun; Kuzyk, Mark G.

    2012-10-01

    It has been shown that the chromophore disperse red 1 azobenzene (DR1) when doped into poly(methyl methacrylate) (PMMA) optical fiber can be used to make an optical cantilever in which an asymmetrically propagating beam at 633nm causes the fiber to bend. The fast response process is purported to be due to elongation of the material as molecules change between cis and trans isomers. In our work, UV light of 350nm will be used to investigate trans to cis somerization, which should induce contraction. Short fiber segments in a three-contactpoint geometry will be used to control the position and tilt of silver- or aluminum-coated coverslips that together with microscope glass slides as the substrate make optically-actuated beam-controlling mounts and Fabry-Perot interferometers. A Michelson interferometer is used to measure the length change of the fiber actuator. Azodye doped liquid crystal (LC) elastomers have been demonstrated to have a photomechanical effect that is at least ten times bigger than thermoplastic-based polymer fiber. However, the optical quality of thermoplastics are much better, enabling the cascading of devices in series. We will report on visible and UV laser-actuation of LC elastomer and polymer device structures using a quadrant photodetector to record the beam deflection caused by the shape change of the material, which will allow for dynamical measurements of the mechanisms. All measurements will be calibrated against a piezoelectric crystal actuator. Photomechanical devices provide an inexpensive but versatile, small-form factor, vibration free and high precision solution to optomechanics, sensing, positioning and other space applications.

  16. Digital Actuator Technology

    SciTech Connect

    Ken Thomas; Ted Quinn; Jerry Mauck; Richard Bockhorst

    2014-09-01

    There are significant developments underway in new types of actuators for power plant active components. Many of these make use of digital technology to provide a wide array of benefits in performance of the actuators and in reduced burden to maintain them. These new product offerings have gained considerable acceptance in use in process plants. In addition, they have been used in conventional power generation very successfully. This technology has been proven to deliver the benefits promised and substantiate the claims of improved performance. The nuclear industry has been reluctant to incorporate digital actuator technology into nuclear plant designs due to concerns due to a number of concerns. These could be summarized as cost, regulatory uncertainty, and a certain comfort factor with legacy analog technology. The replacement opportunity for these types of components represents a decision point for whether to invest in more modern technology that would provide superior operational and maintenance benefits. Yet, the application of digital technology has been problematic for the nuclear industry, due to qualification and regulatory issues. With some notable exceptions, the result has been a continuing reluctance to undertake the risks and uncertainties of implementing digital actuator technology when replacement opportunities present themselves. Rather, utilities would typically prefer to accept the performance limitations of the legacy analog actuator technologies to avoid impacts to project costs and schedules. The purpose of this report is to demonstrate that the benefits of digital actuator technology can be significant in terms of plant performance and that it is worthwhile to address the barriers currently holding back the widespread development and use of this technology. It addresses two important objectives in pursuit of the beneficial use of digital actuator technology for nuclear power plants: 1. To demonstrate the benefits of digital actuator

  17. Thermally actuated mechanical systems

    NASA Astrophysics Data System (ADS)

    Sul, Onejae

    This thesis will discuss the generation of controlled sub-micron motions using novel micro actuators. Our research focuses on the development of an arm-type actuator and a free-motion locomotive walking device. Nano-science and nano-technology focuses on the creation of novel functional materials and also at the development of new fabrication techniques incorporating them. In the fields of novel fabrication techniques, manipulations of micron or sub-micron objects by micro actuators have been suggested in the science and engineering societies for mainly two reasons. From a scientific standpoint, new tools enable new prospective sciences, as is evident from the development of the atomic force microscope. From an engineering standpoint, the miniaturization of manipulation tools will require less material and less energy during a material's production. In spite of such importance, progress in the actuator miniaturization is in a primitive state, especially for the micro mobile devices. The thesis will be a key step in pursuit of this goal with an emphasis on generating motions. Our static actuator uses the excellent elastic properties of multiwall carbon nanotubes as a template for a bimorph system. Deflections in response to temperature variations are demonstrated. The mobile device itself is a bimorph system consisting of thin metal films. Control mechanisms for its velocity and steering are discussed. Finally, fundamental limits on the capabilities of the two devices in a more general sense are discussed under via laws of physics.

  18. Torsional Ratcheting Actuating System

    SciTech Connect

    BARNES,STEPHEN MATTHEW; MILLER,SAMUEL L.; RODGERS,M. STEVEN; BITSIE,FERNANDO

    2000-01-24

    A new type of surface micromachined ratcheting actuation system has been developed at the Microelectronics Development Laboratory at Sandia National Laboratories. The actuator uses a torsional electrostatic comb drive that is coupled to an external ring gear through a ratcheting scheme. The actuator can be operated with a single square wave, has minimal rubbing surfaces, maximizes comb finger density, and can be used for open-loop position control. The prototypes function as intended with a minimum demonstrated operating voltage of 18V. The equations of motion are developed for the torsional electrostatic comb drive. The resonant frequency, voltage vs. displacement and force delivery characteristics are predicted and compared with the fabricated device's performance.

  19. 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. PMID:24954808

  20. An Easy Method for Preparing Presentation Slides.

    ERIC Educational Resources Information Center

    Wright, Norman A.; Blevins, Dennis D.

    1984-01-01

    Describes a simplified method of preparing 35mm projection slides with a minimum of equipment and expertise. The quality of these slides compares favorably to professionally produced diazo slides. Twenty-five slides can easily be prepared in less than three hours. Material cost per slide is comparable to professional color slide processing. (JN)

  1. 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.

  2. 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.

  3. Tetherless thermobiochemically actuated microgrippers

    PubMed Central

    Leong, Timothy G.; Randall, Christina L.; Benson, Bryan R.; Bassik, Noy; Stern, George M.; Gracias, David H.

    2009-01-01

    We demonstrate mass-producible, tetherless microgrippers that can be remotely triggered by temperature and chemicals under biologically relevant conditions. The microgrippers use a self-contained actuation response, obviating the need for external tethers in operation. The grippers can be actuated en masse, even while spatially separated. We used the microgrippers to perform diverse functions, such as picking up a bead on a substrate and the removal of cells from tissue embedded at the end of a capillary (an in vitro biopsy). PMID:19139411

  4. Fault tolerant linear actuator

    DOEpatents

    Tesar, Delbert

    2004-09-14

    In varying embodiments, the fault tolerant linear actuator of the present invention is a new and improved linear actuator with fault tolerance and positional control that may incorporate velocity summing, force summing, or a combination of the two. In one embodiment, the invention offers a velocity summing arrangement with a differential gear between two prime movers driving a cage, which then drives a linear spindle screw transmission. Other embodiments feature two prime movers driving separate linear spindle screw transmissions, one internal and one external, in a totally concentric and compact integrated module.

  5. Hydraulic involute cam actuator

    DOEpatents

    Love, Lonnie J.; Lind, Randall F.

    2011-11-01

    Mechanical joints are provided in which the angle between a first coupled member and a second coupled member may be varied by mechanical actuators. In some embodiments the angle may be varied around a pivot axis in one plane and in some embodiments the angle may be varied around two pivot axes in two orthogonal planes. The joints typically utilize a cam assembly having two lobes with an involute surface. Actuators are configured to push against the lobes to vary the rotation angle between the first and second coupled member.

  6. 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

  7. Conceptual hermetically sealed elbow actuator

    NASA Technical Reports Server (NTRS)

    Wuenscher, H. F.

    1968-01-01

    Electrically or hydraulically powered, hermetically sealed angular or rotary actuator deflects mechanical members over a range of plus or minus 180 degrees. The actuator design provides incremental flexures which keep the local deflection rate within elastic limits.

  8. Low-Shock Pyrotechnic Actuator

    NASA Technical Reports Server (NTRS)

    Lucy, M. H.

    1984-01-01

    Miniature 1-ampere, 1-watt pyrotechnic actuator enclosed in flexible metal bellows. Bellows confines outgassing products, and pyrotechnic shock reduction achieved by action of bellows, gas cushion within device, and minimum use of pyrotechnic material. Actuator inexpensive, compact, and lightweight.

  9. Applications of dielectric elastomer actuators

    NASA Astrophysics Data System (ADS)

    Pelrine, Ron; Sommer-Larsen, Peter; Kornbluh, Roy D.; Heydt, Richard; Kofod, Guggi; Pei, Qibing; Gravesen, Peter

    2001-07-01

    Dielectric elastomer actuators, based on the field-induced deformation of elastomeric polymers with compliant electrodes, can produce a large strain response, combined with a fast response time and high electromechanical efficiency. This unique performance, combined with other factors such as low cost, suggests many potential applications, a wide range of which are under investigation. Applications that effectively exploit the properties of dielectric elastomers include artificial muscle actuators for robots; low-cost, lightweight linear actuators; solid- state optical devices; diaphragm actuators for pumps and smart skins; acoustic actuators; and rotary motors. Issues that may ultimately determine the success or failure of the actuation technology for specific applications include the durability of the actuator, the performance of the actuator under load, operating voltage and power requirements, and electronic driving circuitry, to name a few.

  10. Understanding flame rods

    SciTech Connect

    McAuley, J.A. Jr.

    1995-11-01

    The flame rod is probably the least understood method of flame detection. Although it is not recommended for oilfired equipment, it is very common on atmospheric, or {open_quotes}in-shot,{close_quotes} gas burners. It is also possible, although not common, to have an application with a constant gas pilot, monitored by a flame rod, and maintaining an oil main flame. Regardless of the application, chances are that flame rods will be encountered during the course of servicing. The technician today must be versatile and able to work on many different types of equipment. One must understand the basic principles of flame rods, and how to correct potential problems. The purpose of a flame detection system is two-fold: (1) to prove there is no flame when there shouldn`t be one, and (2) to prove there is a flame when there should be one. Flame failure response time is very important. This is the amount of time it takes to realize there is a loss of flame, two to four seconds is typical today. Prior to flame rods, either bi-metal or thermocouple type flame detectors were common. The response time for these detectors was up to three minutes, seldom less than one minute.

  11. Angular-Momentum-Compensating Actuator

    NASA Technical Reports Server (NTRS)

    Wiktor, Peter J.

    1988-01-01

    Reactionless actuator developed for instrument-pointing platforms on flexible spacecraft; by eliminating reactions, actuator changes aiming angle of platform without inducing vibrations in spacecraft, eliminateing vibrations in point angle of instrument platform. Actuator used on Earth in such systems as helicopter platforms for television cameras in law enforcement and news telecasts.

  12. Electromechanical flight control actuator

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The feasibility of using an electromechanical actuator (EMA) as the primary flight control equipment in aerospace flight is examined. The EMA motor design is presented utilizing improved permanent magnet materials. The necessary equipment to complete a single channel EMA using the single channel power electronics breadboard is reported. The design and development of an improved rotor position sensor/tachometer is investigated.

  13. Bistable microelectromechanical actuator

    DOEpatents

    Fleming, J.G.

    1999-02-02

    A bistable microelectromechanical (MEM) actuator is formed on a substrate and includes a stressed membrane of generally rectangular shape that upon release assumes a curvilinear cross-sectional shape due to attachment at a midpoint to a resilient member and at opposing edges to a pair of elongate supports. The stressed membrane can be electrostatically switched between a pair of mechanical states having mirror-image symmetry, with the MEM actuator remaining in a quiescent state after a programming voltage is removed. The bistable MEM actuator according to various embodiments of the present invention can be used to form a nonvolatile memory element, an optical modulator (with a pair of mirrors supported above the membrane and moving in synchronism as the membrane is switched), a switchable mirror (with a single mirror supported above the membrane at the midpoint thereof) and a latching relay (with a pair of contacts that open and close as the membrane is switched). Arrays of bistable MEM actuators can be formed for applications including nonvolatile memories, optical displays and optical computing. 49 figs.

  14. Bistable microelectromechanical actuator

    DOEpatents

    Fleming, James G.

    1999-01-01

    A bistable microelectromechanical (MEM) actuator is formed on a substrate and includes a stressed membrane of generally rectangular shape that upon release assumes a curvilinear cross-sectional shape due to attachment at a midpoint to a resilient member and at opposing edges to a pair of elongate supports. The stressed membrane can be electrostatically switched between a pair of mechanical states having mirror-image symmetry, with the MEM actuator remaining in a quiescent state after a programming voltage is removed. The bistable MEM actuator according to various embodiments of the present invention can be used to form a nonvolatile memory element, an optical modulator (with a pair of mirrors supported above the membrane and moving in synchronism as the membrane is switched), a switchable mirror (with a single mirror supported above the membrane at the midpoint thereof) and a latching relay (with a pair of contacts that open and close as the membrane is switched). Arrays of bistable MEM actuators can be formed for applications including nonvolatile memories, optical displays and optical computing.

  15. Actuators Acting without Actin.

    PubMed

    Geitmann, Anja

    2016-06-30

    Plant actuators move organs, allowing the plant to respond to environmental cues or perform other mechanical tasks. In Cardamine hursuta the dispersal of seeds is accomplished by explosive opening of the fruit. The biomechanical mechanism relies on a complex interplay between turgor regulation and cell wall mechanical properties. PMID:27368097

  16. "Mighty Worm" Piezoelectric Actuator

    NASA Technical Reports Server (NTRS)

    Bamford, Robert M.; Wada, Ben K.; Moore, Donald M.

    1994-01-01

    "Mighty Worm" piezoelectric actuator used as adjustable-length structural member, active vibrator or vibration suppressor, and acts as simple (fixed-length) structural member when inactive. Load force not applied to piezoelectric element in simple-structural-member mode. Piezoelectric element removed from load path when not in use.

  17. Intramedullary rodding in osteogenesis imperfecta.

    PubMed

    Mulpuri, K; Joseph, B

    2000-01-01

    The results of intramedullary rodding of long bones of 16 children with osteogenesis imperfecta, over a 10-year period, were analyzed. Sheffield elongating rods or non-elongating rods were used. The frequency of fractures was dramatically reduced after implantation of either type of rod, and the ambulatory status improved in all instances. The results were significantly better after Sheffield rodding with regard to the frequency of complications requiring reoperations and the longevity of the rods. Migration of the rods, encountered frequently, appears to be related to improper placement of the rods in the bone. It seems likely that if care is taken to ensure precise placement of a rod of appropriate size, several of these complications may be avoided. PMID:10739296

  18. Magnetic circuit design for miniaturized magnetic shape memory alloy actuators

    NASA Astrophysics Data System (ADS)

    Bolzmacher, C.

    2013-05-01

    Magnetic shape memory alloy (MSMA) is a relatively new kind of smart material. Upon application of a large magnetic field, it exhibits actuation strains up to 10% similar to thermal shape memory alloy (SMA) but shows significantly reduced response time in the millisecond range. Currently, application is restricted by the brittleness of the single crystal material, its nonlinear behaviour and the difficulty to generate and apply a magnetic field around 0.6T in order to exploit the full actuation potential. The focus of this work is on the design of miniaturized magnetic circuits for bulk MSMAs. Various circuit designs are compared such as toroidal and series-parallel shapes. Equivalent circuit as well as finite element simulation is used to increase the magnetic field in a characteristic air gap where the smart material is placed. A symmetrical toroid coil layout with the MSMA element at the center that allows easy integration of the actuator in various applications is described. Static characterization results of this actuator are provided. Using the described magnetic circuit and 5M - MSMA rods with dimensions of 20x2.5x1mm3, a peak displacement of 0.8mm and a blocked force of 4.5N was obtained. Further design guidelines for such miniaturized actuators are given.

  19. Magnetic Actuation of Self-Assembled DNA Hinges

    NASA Astrophysics Data System (ADS)

    Lauback, S.; Mattioli, K.; Armstrong, M.; Miller, C.; Pease, C.; Castro, C.; Sooryakumar, R.

    DNA nanotechnology offers a broad range of applications spanning from the creation of nanoscale devices, motors and nanoparticle templates to the development of precise drug delivery systems. Central to advancing this technology is the ability to actuate or reconfigure structures in real time, which is currently achieved primarily by DNA strand displacement yielding slow actuation times (about 1-10min). Here we exploit superparamagnetic beads to magnetically actuate DNA structures which also provides a system to measure forces associated with molecular interactions. DNA nanodevices are folded using DNA origami, whereby a long single-stranded DNA is folded into a precise compact geometry using hundreds of short oligonucleotides. Our DNA nanodevice is a nanohinge from which rod shaped DNA nanostructures are polymerized into micron-scale filaments forming handles for actuation. By functionalizing one arm of the hinge and the filament ends, the hinge can be attached to a surface while still allowing an arm to rotate and the filaments can be labeled with magnetic beads enabling the hinge to be actuated almost instantaneously by external magnetic fields. These results lay the groundwork to establish real-time manipulation and direct force application of DNA constructs.

  20. Pneumatic artificial muscle actuators for compliant robotic manipulators

    NASA Astrophysics Data System (ADS)

    Robinson, Ryan Michael

    Robotic systems are increasingly being utilized in applications that require interaction with humans. In order to enable safe physical human-robot interaction, light weight and compliant manipulation are desirable. These requirements are problematic for many conventional actuation systems, which are often heavy, and typically use high stiffness to achieve high performance, leading to large impact forces upon collision. However, pneumatic artificial muscles (PAMs) are actuators that can satisfy these safety requirements while offering power-to-weight ratios comparable to those of conventional actuators. PAMs are extremely lightweight actuators that produce force in response to pressurization. These muscles demonstrate natural compliance, but have a nonlinear force-contraction profile that complicates modeling and control. This body of research presents solutions to the challenges associated with the implementation of PAMs as actuators in robotic manipulators, particularly with regard to modeling, design, and control. An existing PAM force balance model was modified to incorporate elliptic end geometry and a hyper-elastic constitutive relationship, dramatically improving predictions of PAM behavior at high contraction. Utilizing this improved model, two proof-of-concept PAM-driven manipulators were designed and constructed; design features included parallel placement of actuators and a tendon-link joint design. Genetic algorithm search heuristics were employed to determine an optimal joint geometry; allowing a manipulator to achieve a desired torque profile while minimizing the required PAM pressure. Performance of the manipulators was evaluated in both simulation and experiment employing various linear and nonlinear control strategies. These included output feedback techniques, such as proportional-integral-derivative (PID) and fuzzy logic, a model-based control for computed torque, and more advanced controllers, such as sliding mode, adaptive sliding mode, and

  1. COMPOSITE CONTROL ROD

    DOEpatents

    Rock, H.R.

    1963-12-24

    A composite control rod for use in controlling a nuclear reactor is described. The control rod is of sandwich construction in which finned dowel pins are utilized to hold together sheets of the neutron absorbing material and nonabsorbing structural material thereby eliminating the need for being dependent on the absorbing material for structural support. The dowel pins perform the function of absorbing the forces due to differential thermal expansion, seating further with the fins into the sheets of material and crushing before damage is done either to the absorbing or non-absorbing material. (AEC)

  2. 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

  3. 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

  4. Fault tolerant small satellite attitude control using adaptive non-singular terminal sliding mode

    NASA Astrophysics Data System (ADS)

    Cao, Lu; Chen, XiaoQian; Sheng, Tao

    2013-06-01

    The Attitude Control System (ACS) plays a pivotal role in the whole performance of the spacecraft on the orbit; therefore, it is vitally important to design the control system with the performance of rapid response, high control precision and insensitive to external perturbations. In the first place, this paper proposes two adaptive nonlinear control algorithms based on the sliding mode control (SMC), which are designed for small satellite attitude control system. The nonlinear dynamics describing the attitude of small satellite is considered in a circle reference orbit, and the stability of the closed-loop system in the presence of external perturbations is investigated. Then, in order to account for accidental or degradation fault in satellite actuators, the fault-tolerant control schemes are presented. Hence, two adaptive fault-tolerant control laws (continuous sliding mode control and non-singular terminal sliding mode control) are developed by adopting the nonlinear analytical model to describe the system, which can guarantee global asymptotic convergence of the attitude control error with the existence of unknown external perturbations. The nonlinear hyperplane based Terminal sliding mode is introduced into the control law design; therefore, the system convergence performance improves and the control error is convergent in "finite time". As a result, the study on the non-singular terminal sliding mode control is the emphasis and the continuous sliding mode control is used to compare with the non-singular terminal sliding mode control. Meanwhile, an adaptive fuzzy algorithm has been proposed to suppress the chattering phenomenon. Moreover, several numerical examples are presented to demonstrate the efficacy of the proposed controllers by correcting for the external perturbations. Simulation results confirm that the suggested methodologies yield high control precision in control. In addition, actuator degradation, actuator stuck and actuator failure for a

  5. Dielectric Actuation of Polymers

    NASA Astrophysics Data System (ADS)

    Niu, Xiaofan

    Dielectric polymers are widely used in a plurality of applications, such as electrical insulation, dielectric capacitors, and electromechanical actuators. Dielectric polymers with large strain deformations under an electric field are named dielectric elastomers (DE), because of their relative low modulus, high elongation at break, and outstanding resilience. Dielectric elastomer actuators (DEA) are superior to traditional transducers as a muscle-like technology: large strains, high energy densities, high coupling efficiency, quiet operation, and light weight. One focus of this dissertation is on the design of DE materials with high performance and easy processing. UV radiation curing of reactive species is studied as a generic synthesis methodology to provide a platform for material scientists to customize their own DE materials. Oligomers/monomers, crosslinkers, and other additives are mixed and cured at appropriate ratios to control the stress-strain response, suppress electromechanical instability of the resulting polymers, and provide stable actuation strains larger than 100% and energy densities higher than 1 J/g. The processing is largely simplified in the new material system by removal of the prestretching step. Multilayer stack actuators with 11% linear strain are demonstrated in a procedure fully compatible with industrial production. A multifunctional DE derivative material, bistable electroactive polymer (BSEP), is invented enabling repeatable rigid-to-rigid deformation without bulky external structures. Bistable actuation allows the polymer actuator to have two distinct states that can support external load without device failure. Plasticizers are used to lower the glass transition temperature to 45 °C. Interpenetrating polymer network structure is established inside the BSEP to suppress electromechanical instability, providing a breakdown field of 194 MV/m and a stable bistable strain as large as 228% with a 97% strain fixity. The application of BSEP

  6. Design, test and model of a hybrid magnetostrictive hydraulic actuator

    NASA Astrophysics Data System (ADS)

    Chaudhuri, Anirban; Yoo, Jin-Hyeong; Wereley, Norman M.

    2009-08-01

    The basic operation of hybrid hydraulic actuators involves high frequency bi-directional operation of an active material that is converted to uni-directional motion of hydraulic fluid using valves. A hybrid actuator was developed using magnetostrictive material Terfenol-D as the driving element and hydraulic oil as the working fluid. Two different lengths of Terfenol-D rod, 51 and 102 mm, with the same diameter, 12.7 mm, were used. Tests with no load and with load were carried out to measure the performance for uni-directional motion of the output piston at different pumping frequencies. The maximum no-load flow rates were 24.8 cm3 s-1 and 22.7 cm3 s-1 with the 51 mm and 102 mm long rods respectively, and the peaks were noted around 325 Hz pumping frequency. The blocked force of the actuator was close to 89 N in both cases. A key observation was that, at these high pumping frequencies, the inertial effects of the fluid mass dominate over the viscous effects and the problem becomes unsteady in nature. In this study, we also develop a mathematical model of the hydraulic hybrid actuator in the time domain to show the basic operational principle under varying conditions and to capture phenomena affecting system performance. Governing equations for the pumping piston and output shaft were obtained from force equilibrium considerations, while compressibility of the working fluid was taken into account by incorporating the bulk modulus. Fluid inertia was represented by a lumped parameter approach to the transmission line model, giving rise to strongly coupled ordinary differential equations. The model was then used to calculate the no-load velocities of the actuator at different pumping frequencies and simulation results were compared with experimental data for model validation.

  7. Automated single-slide staining device. [in clinical bacteriology

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    An automatic single-slide Gram staining device is described. A timer-actuated solenoid controls the dispensing of gentian violet, Gram iodine solution, decolorizer, and 1% aqueous safranin in proper sequence and for the time required for optimum staining. The amount of stain or reagent delivered is controlled by means of stopcocks below each solenoid. Used stains and reagents can be flushed automatically or manually. Smears Gram stained automatically are equal in quality to those prepared manually. The time to complete one Gram cycle is 4.80 min.

  8. Axial Thermal Rotation of Slender Rods

    NASA Astrophysics Data System (ADS)

    Li, Dichuan; Fakhri, Nikta; Pasquali, Matteo; Biswal, Sibani Lisa

    2011-05-01

    Axial rotational diffusion of rodlike polymers is important in processes such as microtubule filament sliding and flagella beating. By imaging the motion of small kinks along the backbone of chains of DNA-linked colloids, we produce a direct and systematic measurement of axial rotational diffusivity of rods both in bulk solution and near a wall. The measured diffusivities decrease linearly with the chain length, irrespective of the distance from a wall, in agreement with slender-body hydrodynamics theory. Moreover, the presence of small kinks does not affect the chain’s axial diffusivity. Our system and measurements provide insights into fundamental axial diffusion processes of slender objects, which encompass a wide range of entities including biological filaments and linear polymer chains.

  9. Appearance Normalization of Histology Slides

    PubMed Central

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

    2011-01-01

    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 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. PMID:25360444

  10. Reusable Launch Vehicle Control In Multiple Time Scale Sliding Modes

    NASA Technical Reports Server (NTRS)

    Shtessel, Yuri; Hall, Charles; Jackson, Mark

    2000-01-01

    A reusable launch vehicle control problem during ascent is addressed via multiple-time scaled continuous sliding mode control. The proposed sliding mode controller utilizes a two-loop structure and provides robust, de-coupled tracking of both orientation angle command profiles and angular rate command profiles in the presence of bounded external disturbances and plant uncertainties. Sliding mode control causes the angular rate and orientation angle tracking error dynamics to be constrained to linear, de-coupled, homogeneous, and vector valued differential equations with desired eigenvalues placement. Overall stability of a two-loop control system is addressed. An optimal control allocation algorithm is designed that allocates torque commands into end-effector deflection commands, which are executed by the actuators. The dual-time scale sliding mode controller was designed for the X-33 technology demonstration sub-orbital launch vehicle in the launch mode. Simulation results show that the designed controller provides robust, accurate, de-coupled tracking of the orientation angle command profiles in presence of external disturbances and vehicle inertia uncertainties. This is a significant advancement in performance over that achieved with linear, gain scheduled control systems currently being used for launch vehicles.

  11. Design and control of a proof-of-concept variable-area exhaust nozzle using shape memory alloy actuators

    NASA Astrophysics Data System (ADS)

    Song, Gangbing; Ma, Ning; Lee, Hou-Jun; Arnold, Steven

    2004-07-01

    There is no reported research of using shape memory alloy (SMA) actuators for variable area exhaust nozzle for a jet engine in the literature, to the authors' best knowledge. SMA actuators have the advantages of high power-to-weight ratio and can result in dramatic weight reduction as compared to hydraulic systems. However, the difficulty of using SMA actuators for controlling variable area exhaust nozzle lies in the fact that the temperature near exhaust nozzle is far higher than the transformation temperature of an SMA actuator. Due to the flexibility and small volume of SMA wire actuators, they can be remotely replaced in a region where temperature is lower than that of its transformation temperature. By exploiting this fact, this paper presents a novel design of a proof-of-concept variable area exhaust nozzle using shape memory alloy wire actuators. The SMA actuators are remotely placed away from the exhaust nozzle area so that the environmental temperature is below their transformation temperature. By electrically heating the SMA actuators, the exhaust nozzle will experience an area reduction of up to 40%. Bias springs will apply forces to return the fan nozzle to the open-up configuration. A feedback controller based sliding mode method is used to regulate the SMA actuators' position. Experimental results demonstrate that the proposed design meets the desired area variation specifications and show the promise of a lightweight and simple exhaust nozzle design by using shape memory alloy actuators.

  12. Microfabricated therapeutic actuators

    SciTech Connect

    Lee, Abraham P.; Northrup, M. Allen; Ciarlo, Dino R.; Krulevitch, Peter A.; Benett, William J.

    1999-01-01

    Microfabricated therapeutic actuators are fabricated using a shape memory polymer (SMP), a polyurethane-based material that undergoes a phase transformation at a specified temperature (Tg). At a temperature above temperature Tg material is soft and can be easily reshaped into another configuration. As the temperature is lowered below temperature Tg the new shape is fixed and locked in as long as the material stays below temperature Tg. Upon reheating the material to a temperature above Tg, the material will return to its original shape. By the use of such SMP material, SMP microtubing can be used as a release actuator for the delivery of embolic coils through catheters into aneurysms, for example. The microtubing can be manufactured in various sizes and the phase change temperature Tg is determinate for an intended temperature target and intended use.

  13. Microfabricated therapeutic actuators

    DOEpatents

    Lee, A.P.; Northrup, M.A.; Ciarlo, D.R.; Krulevitch, P.A.; Benett, W.J.

    1999-06-15

    Microfabricated therapeutic actuators are fabricated using a shape memory polymer (SMP), a polyurethane-based material that undergoes a phase transformation at a specified temperature (Tg). At a temperature above temperature Tg material is soft and can be easily reshaped into another configuration. As the temperature is lowered below temperature Tg the new shape is fixed and locked in as long as the material stays below temperature Tg. Upon reheating the material to a temperature above Tg, the material will return to its original shape. By the use of such SMP material, SMP microtubing can be used as a release actuator for the delivery of embolic coils through catheters into aneurysms, for example. The microtubing can be manufactured in various sizes and the phase change temperature Tg is determinate for an intended temperature target and intended use. 8 figs.

  14. Electrical Actuation Technology Bridging

    NASA Technical Reports Server (NTRS)

    Hammond, Monica (Compiler); Sharkey, John (Compiler)

    1993-01-01

    This document contains the proceedings of the NASA Electrical Actuation Technology Bridging (ELA-TB) Workshop held in Huntsville, Alabama, September 29-October 1, 1992. The workshop was sponsored by the NASA Office of Space Systems Development and Marshall Space Flight Center (MSFC). The workshop addressed key technologies bridging the entire field of electrical actuation including systems methodology, control electronics, power source systems, reliability, maintainability, and vehicle health management with special emphasis on thrust vector control (TVC) applications on NASA launch vehicles. Speakers were drawn primarily from industry with participation from universities and government. In addition, prototype hardware demonstrations were held at the MSFC Propulsion Laboratory each afternoon. Splinter sessions held on the final day afforded the opportunity to discuss key issues and to provide overall recommendations. Presentations are included in this document.

  15. Microfabricated therapeutic actuator mechanisms

    DOEpatents

    Northrup, Milton A.; Ciarlo, Dino R.; Lee, Abraham P.; Krulevitch, Peter A.

    1997-01-01

    Electromechanical microstructures (microgrippers), either integrated circuit (IC) silicon-based or precision machined, to extend and improve the application of catheter-based interventional therapies for the repair of aneurysms in the brain or other interventional clinical therapies. These micromechanisms can be specifically applied to release platinum coils or other materials into bulging portions of the blood vessels also known as aneurysms. The "micro" size of the release mechanism is necessary since the brain vessels are the smallest in the body. Through a catheter more than one meter long, the micromechanism located at one end of the catheter can be manipulated from the other end thereof. The microgripper (micromechanism) of the invention will also find applications in non-medical areas where a remotely actuated microgripper or similar actuator would be useful or where micro-assembling is needed.

  16. Microfabricated therapeutic actuator mechanisms

    DOEpatents

    Northrup, M.A.; Ciarlo, D.R.; Lee, A.P.; Krulevitch, P.A.

    1997-07-08

    Electromechanical microstructures (microgrippers), either integrated circuit (IC) silicon-based or precision machined, to extend and improve the application of catheter-based interventional therapies for the repair of aneurysms in the brain or other interventional clinical therapies. These micromechanisms can be specifically applied to release platinum coils or other materials into bulging portions of the blood vessels also known as aneurysms. The ``micro`` size of the release mechanism is necessary since the brain vessels are the smallest in the body. Through a catheter more than one meter long, the micromechanism located at one end of the catheter can be manipulated from the other end thereof. The microgripper (micromechanism) of the invention will also find applications in non-medical areas where a remotely actuated microgripper or similar actuator would be useful or where micro-assembling is needed. 22 figs.

  17. Scissor thrust valve actuator

    DOEpatents

    DeWall, Kevin G.; Watkins, John C; Nitzel, Michael E.

    2006-08-29

    Apparatus for actuating a valve includes a support frame and at least one valve driving linkage arm, one end of which is rotatably connected to a valve stem of the valve and the other end of which is rotatably connected to a screw block. A motor connected to the frame is operatively connected to a motor driven shaft which is in threaded screw driving relationship with the screw block. The motor rotates the motor driven shaft which drives translational movement of the screw block which drives rotatable movement of the valve driving linkage arm which drives translational movement of the valve stem. The valve actuator may further include a sensory control element disposed in operative relationship with the valve stem, the sensory control element being adapted to provide control over the position of the valve stem by at least sensing the travel and/or position of the valve stem.

  18. Microgravity Isolation Control System Design Via High-Order Sliding Mode Control

    NASA Technical Reports Server (NTRS)

    Shkolnikov, Ilya; Shtessel, Yuri; Whorton, Mark S.; Jackson, Mark

    2000-01-01

    Vibration isolation control system design for a microgravity experiment mount is considered. The controller design based on dynamic sliding manifold (DSM) technique is proposed to attenuate the accelerations transmitted to an isolated experiment mount either from a vibrating base or directly generated by the experiment, as well as to stabilize the internal dynamics of this nonminimum phase plant. An auxiliary DSM is employed to maintain the high-order sliding mode on the primary sliding manifold in the presence of uncertain actuator dynamics of second order. The primary DSM is designed for the closed-loop system in sliding mode to be a filter with given characteristics with respect to the input external disturbances.

  19. Experimental and analytical tools for evaluation of Stirling engine rod seal behavior

    NASA Technical Reports Server (NTRS)

    Krauter, A. I.; Cheng, H. S.

    1979-01-01

    The first year of a two year experimental and analytical program is reported. The program is directed at the elastohydrodynamic behavior of sliding elastomeric rod seals for the Stirling engine. During the year, experimental and analytical tools were developed for evaluating seal leakage, seal friction, and the fluid film thickness at the seal/cylinder interface.

  20. Anchor for Fiberglas Guy Rod

    NASA Technical Reports Server (NTRS)

    Wilson, A. H.

    1982-01-01

    Solution to problem of anchoring fiberglas guy rods to install nut with threads on outer circumference, followed by aluminum sleeve. Sleeve has opening oval at upper and round at bottom end. End of rod is split so fiberglas wedge can be inserted to form V-shaped end. Spread end of rod fits into tapered hole in sleeve and threaded aluminum coupling is put over rod and sleeve.

  1. Thermally actuated thermionic switch

    DOEpatents

    Barrus, D.M.; Shires, C.D.

    1982-09-30

    A thermally actuated thermionic switch which responds to an increase of temperature by changing from a high impedance to a low impedance at a predictable temperature set point. The switch has a bistable operation mode switching only on temperature increases. The thermionic material may be a metal which is liquid at the desired operation temperature and held in matrix in a graphite block reservoir, and which changes state (ionizes, for example) so as to be electrically conductive at a desired temperature.

  2. Thermally actuated thermionic switch

    DOEpatents

    Barrus, Donald M.; Shires, Charles D.

    1988-01-01

    A thermally actuated thermionic switch which responds to an increase of temperature by changing from a high impedance to a low impedance at a predictable temperature set point. The switch has a bistable operation mode switching only on temperature increases. The thermionic material may be a metal which is liquid at the desired operation temperature and held in matrix in a graphite block reservoir, and which changes state (ionizes, for example) so as to be electrically conductive at a desired temperature.

  3. Passively actuated valve

    SciTech Connect

    Modro, S. Michael; Ougouag, Abderrafi M.

    2005-09-20

    A passively actuated valve for isolating a high pressure zone from a low pressure zone and discontinuing the isolation when the pressure in the high pressure zone drops below a preset threshold. If the pressure in the high pressure zone drops below the preset threshold, the valve opens and allows flow from the high pressure zone to the low pressure zone. The valve remains open allowing pressure equalization and back-flow should a pressure inversion between the two pressure zone occur.

  4. Shape memory alloy actuator

    DOEpatents

    Varma, Venugopal K.

    2001-01-01

    An actuator for cycling between first and second positions includes a first shaped memory alloy (SMA) leg, a second SMA leg. At least one heating/cooling device is thermally connected to at least one of the legs, each heating/cooling device capable of simultaneously heating one leg while cooling the other leg. The heating/cooling devices can include thermoelectric and/or thermoionic elements.

  5. Dissolution actuated sample container

    DOEpatents

    Nance, Thomas A.; McCoy, Frank T.

    2013-03-26

    A sample collection vial and process of using a vial is provided. The sample collection vial has an opening secured by a dissolvable plug. When dissolved, liquids may enter into the interior of the collection vial passing along one or more edges of a dissolvable blocking member. As the blocking member is dissolved, a spring actuated closure is directed towards the opening of the vial which, when engaged, secures the vial contents against loss or contamination.

  6. Microelectromechanical (MEM) thermal actuator

    DOEpatents

    Garcia, Ernest J.; Fulcher, Clay W. G.

    2012-07-31

    Microelectromechanical (MEM) buckling beam thermal actuators are disclosed wherein the buckling direction of a beam is constrained to a desired direction of actuation, which can be in-plane or out-of-plane with respect to a support substrate. The actuators comprise as-fabricated, linear beams of uniform cross section supported above the substrate by supports which rigidly attach a beam to the substrate. The beams can be heated by methods including the passage of an electrical current through them. The buckling direction of an initially straight beam upon heating and expansion is controlled by incorporating one or more directional constraints attached to the substrate and proximal to the mid-point of the beam. In the event that the beam initially buckles in an undesired direction, deformation of the beam induced by contact with a directional constraint generates an opposing force to re-direct the buckling beam into the desired direction. The displacement and force generated by the movement of the buckling beam can be harnessed to perform useful work, such as closing contacts in an electrical switch.

  7. Cylindrical Piezoelectric Fiber Composite Actuators

    NASA Technical Reports Server (NTRS)

    Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.

    2008-01-01

    The use of piezoelectric devices has become widespread since Pierre and Jacques Curie discovered the piezoelectric effect in 1880. Examples of current applications of piezoelectric devices include ultrasonic transducers, micro-positioning devices, buzzers, strain sensors, and clocks. The invention of such lightweight, relatively inexpensive piezoceramic-fiber-composite actuators as macro fiber composite (MFC) actuators has made it possible to obtain strains and displacements greater than those that could be generated by prior actuators based on monolithic piezoceramic sheet materials. MFC actuators are flat, flexible actuators designed for bonding to structures to apply or detect strains. Bonding multiple layers of MFC actuators together could increase force capability, but not strain or displacement capability. Cylindrical piezoelectric fiber composite (CPFC) actuators have been invented as alternatives to MFC actuators for applications in which greater forces and/or strains or displacements may be required. In essence, a CPFC actuator is an MFC or other piezoceramic fiber composite actuator fabricated in a cylindrical instead of its conventional flat shape. Cylindrical is used here in the general sense, encompassing shapes that can have circular, elliptical, rectangular or other cross-sectional shapes in the planes perpendicular to their longitudinal axes.

  8. REACTOR CONTROL ROD OPERATING SYSTEM

    DOEpatents

    Miller, G.

    1961-12-12

    A nuclear reactor control rod mechanism is designed which mechanically moves the control rods into and out of the core under normal conditions but rapidly forces the control rods into the core by catapultic action in the event of an emergency. (AEC)

  9. Hafnium stainless steel absorber rod for control rod

    SciTech Connect

    Charnley, J.E.; Cearley, J.E.; Dixon, R.C.; Izzo, K.R.; Aiello, L.L.

    1989-08-01

    This patent describes an improvement in a control rod having a stainless steel body for enclosing a neutron absorbing poison, the control rod having movement along an axial direction for insertion into and out of a nuclear reactor for controlling a nuclear reaction. The improvement comprising: a piece of hafnium; a piece of stainless steel joined to the hafnium by a thin diffusion interface created by friction welding. The hafnium and the stainless steel oriented serially in the axial direction with the thin diffusion interface disposed normal to the axial direction of the control rod movement; means for confining the hafnium to movement along the axial direction with the control rod; and means for attaching the piece of stainless steel to the remaining portion of the control rod to load the weld therebetween under compression or tension during the control rod movement. Whereby the thin diffusion interface is loaded in tension or compression only upon dynamic movement of the control rod.

  10. Thermionic switched self-actuating reactor shutdown system

    DOEpatents

    Barrus, Donald M.; Shires, Charles D.; Brummond, William A.

    1989-01-01

    A self-actuating reactor shutdown system incorporating a thermionic switched electromagnetic latch arrangement which is responsive to reactor neutron flux changes and to reactor coolant temperature changes. The system is self-actuating in that the sensing thermionic device acts directly to release (scram) the control rod (absorber) without reference or signal from the main reactor plant protective and control systems. To be responsive to both temperature and neutron flux effects, two detectors are used, one responsive to reactor coolant temperatures, and the other responsive to reactor neutron flux increase. The detectors are incorporated into a thermionic diode connected electrically with an electromagnetic mechanism which under normal reactor operating conditions holds the the control rod in its ready position (exterior of the reactor core). Upon reaching either a specified temperature or neutron flux, the thermionic diode functions to short-circuit the electromagnetic mechanism causing same to lose its holding power and release the control rod, which drops into the reactor core region under gravitational force.

  11. Solar-Cell Slide Rule

    NASA Technical Reports Server (NTRS)

    Yamakawa, K. A.

    1983-01-01

    Slide rule relates efficiency, impurity types, impurity concentrations, and process types. Solar cell slide rule calculations are determination of allowable impurity concentration for nonredistributive process, determination of impurity buildup factor for redistributive process and determination of allowable impurity concentration for redistributive process.

  12. X-Frame-actuator servo-flap acuation system for rotor control

    NASA Astrophysics Data System (ADS)

    Prechtl, Eric F.; Hall, Steven R.

    1998-07-01

    A design is presented of a 1/6 Mach scaled CH-47D rotor blade incorporating a X-Frame discrete actuator for control of a trailing edge servo-flap. The second generation design of the X-Frame actuator is described focusing on the design changes made from the actuator prototype. The function of the components that restrain the actuator to the rotor blade and connect it to the servo-flap are described. The major challenge in placing a discrete actuator into a rotor blade is in allowing the required functionality in the aggressive acceleration environment of the blade. In particular, a new centrifugal flexure is used to restrain the actuator in the spanwise direction and special fittings are incorporated into the blades to allow the required actuator degrees of freedom while reacting the out of plane vibrational accelerations of the blade. Concentric steel rods are used to transfer actuator motion to the servo-flap and to eliminate the compliant blade fairing from the actuation load path. A slotted flap design was used to reduce the required hinge moments. The aerodynamic implications of using such a flap design are described. Furthermore, retention of the flap and the pre-stress of the actuator were accomplished by a steel wire centered on the flap rotational axis. The design of this part and its influence on choosing an optimum flap length is discussed. The manufacture of the composite rotor blades is described. The diversion of composite unidirectional plies to allow access to the actuator bay within the blade spar is described.

  13. SAFETY SYSTEM FOR CONTROL ROD

    DOEpatents

    Paget, J.A.

    1963-05-14

    A structure for monitoring the structural continuity of a control rod foi a neutron reactor is presented. A electric conductor readily breakable under mechanical stress is fastened along the length of the control rod at a plurality of positions and forms a closed circuit with remote electrical components responsive to an open circuit. A portion of the conductor between the control rod and said components is helically wound to allow free and normally unrestricted movement of the segment of conductor secured to the control rod relative to the remote components. Any break in the circuit is indicative of control rod breakage. (AEC)

  14. Locked-wrap fuel rod

    DOEpatents

    Kaplan, Samuel; Chertock, Alan J.; Punches, James R.

    1977-01-01

    A method for spacing fast reactor fuel rods using a wire wrapper improved by orienting the wire-wrapped fuel rods in a unique manner which introduces desirable performance characteristics not attainable by previous wire-wrapped designs. Use of this method in a liquid metal fast breeder reactor results in: (a) improved mechanical performance, (b) improved rod-to-rod contact, (c) reduced steel volume, and (d) improved thermal-hydraulic performance. The method produces a "locked wrap" design which tends to lock the rods together at each of the wire cluster locations.

  15. Telescoping cylindrical piezoelectric fiber composite actuator assemblies

    NASA Technical Reports Server (NTRS)

    Allison, Sidney G. (Inventor); Shams, Qamar A. (Inventor); Fox, Robert L. (Inventor); Fox, legal representative, Christopher L. (Inventor); Fox Chattin, legal representative, Melanie L. (Inventor)

    2010-01-01

    A telescoping actuator assembly includes a plurality of cylindrical actuators in a concentric arrangement. Each cylindrical actuator is at least one piezoelectric fiber composite actuator having a plurality of piezoelectric fibers extending parallel to one another and to the concentric arrangement's longitudinal axis. Each cylindrical actuator is coupled to concentrically-adjacent ones of the cylindrical actuators such that the plurality of cylindrical actuators can experience telescopic movement. An electrical energy source coupled to the cylindrical actuators applies actuation energy thereto to generate the telescopic movement.

  16. 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. PMID:25863518

  17. 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

  18. APPARATUS FOR SHEATHING RODS

    DOEpatents

    Ford, W.K.; Wyatt, M.; Plail, S.

    1961-08-01

    An arrangement is described for sealing a solid body of nuclear fuel, such as a uranium metal rod, into a closelyfitting thin metallic sheath with an internal atmosphere of inert gas. The sheathing process consists of subjecting the sheath, loaded with the nuclear fuel body, to the sequential operations of evacuation, gas-filling, drawing (to entrap inert gas and secure close contact between sheath and body), and sealing. (AEC)

  19. The application of variable explosive chamber testing to actuator testing

    SciTech Connect

    Munger, A.C.

    1987-01-01

    The Variable Explosive Chamber (VEC) test setup has been used for research, design, and quality control of pyrotechnic actuators. The test was devised by Sandia National Laboratories, Livermore. The results obtained during component development are covered in this report, along with fault analysis of the test device. The data from components at various powder densities and pyrotehnic masses are shown. The effects of test hardware design, such as press fits or sliding fits, are shown. The effects of test hardware design, such as press fits or sliding fits, are shown. The hardware used by Mound was fabricated by a specialty vendor and is no longer available. Therefore, a new test design is presented, along with preliminary data that correlate the two test designs. 3 refs., 15 figs.

  20. Cellular Pressure-Actuated Joint

    NASA Technical Reports Server (NTRS)

    McGuire, John R.

    2003-01-01

    A modification of a pressure-actuated joint has been proposed to improve its pressure actuation in such a manner as to reduce the potential for leakage of the pressurizing fluid. The specific joint for which the modification is proposed is a field joint in a reusable solid-fuel rocket motor (RSRM), in which the pressurizing fluid is a mixture of hot combustion gases. The proposed modification could also be applicable to other pressure-actuated joints of similar configuration.

  1. Direct drive field actuator motors

    DOEpatents

    Grahn, A.R.

    1998-03-10

    A positive-drive field actuator motor is described which includes a stator carrying at least one field actuator which changes in dimension responsive to application of an energy field, and at least one drive shoe movable by the dimensional changes of the field actuator to contact and move a rotor element with respect to the stator. Various embodiments of the motor are disclosed, and the rotor element may be moved linearly or arcuately. 62 figs.

  2. Fault-tolerant rotary actuator

    DOEpatents

    Tesar, Delbert

    2006-10-17

    A fault-tolerant actuator module, in a single containment shell, containing two actuator subsystems that are either asymmetrically or symmetrically laid out is provided. Fault tolerance in the actuators of the present invention is achieved by the employment of dual sets of equal resources. Dual resources are integrated into single modules, with each having the external appearance and functionality of a single set of resources.

  3. Direct drive field actuator motors

    DOEpatents

    Grahn, Allen R.

    1998-01-01

    A positive-drive field actuator motor including a stator carrying at least one field actuator which changes in dimension responsive to application of an energy field, and at least one drive shoe movable by the dimensional changes of the field actuator to contact and move a rotor element with respect to the stator. Various embodiments of the motor are disclosed, and the rotor element may be moved linearly or arcuately.

  4. Vortices in vibrated granular rods

    NASA Astrophysics Data System (ADS)

    Neicu, Toni; Kudrolli, Arshad

    2002-03-01

    We report the first experimental observation of vortex patterns in granular rods inside a container that is vibrated vertically . The experiments were carried out with an anodized aluminum circular container which is rigidly attached to an electromagnetic shaker and the patterns are imaged using a high-frame rate digital camera. At low rod numbers and driving amplitudes, the rods are observed to lie horizontally. Above a critical number or packing fraction of rods, moving domains of vertical rods are spontaneously observed to form which coexist with horizontal rods. These small domains of vertical rods coarsen over time to form a few large vortices. The size of the vortices increases with the number of rods. We are able to track the ends of the vertical rods and obtain the velocity fields of the vortices. The mean azimuthal velocity as a function of distance from the center of the vortex is obtained as a function of the packing fraction. We will report the phase diagram of the various patterns observed as function of number of rods and driving amplitude. The mechanism for the formation and motion of the domains of vertical rods will be also discussed.

  5. Safety rod latch inspection

    SciTech Connect

    Leader, D.R.

    1992-02-01

    During an attempt to raise control rods from the 100 K reactor in December, one rod could not be withdrawn. Subsequent investigation revealed that a small button'' in the latch mechanism had broken off of the lock plunger'' and was wedged in a position that prevented rod withdrawal. Concern that this failure may have resulted from corrosion or some other metallurgical problem resulted in a request that SRL examine six typical latch mechanisms from the 100 L reactor by use of radiography and metallography. During the examination of the L-Area latches, a failed latch mechanism from the 100 K reactor was added to the investigation. Fourteen latches that had a history of problems were removed from K-Area and sent to SRL for inclusion in this study the week after the original seven assemblies were examined, bringing the total of latch assemblies discussed in this report to twenty one. Results of the examination of the K-Area latch that initiated this study is not included in this report.

  6. Safety rod latch inspection

    SciTech Connect

    Leader, D.R.

    1992-02-01

    During an attempt to raise control rods from the 100 K reactor in December, one rod could not be withdrawn. Subsequent investigation revealed that a small ``button`` in the latch mechanism had broken off of the ``lock plunger`` and was wedged in a position that prevented rod withdrawal. Concern that this failure may have resulted from corrosion or some other metallurgical problem resulted in a request that SRL examine six typical latch mechanisms from the 100 L reactor by use of radiography and metallography. During the examination of the L-Area latches, a failed latch mechanism from the 100 K reactor was added to the investigation. Fourteen latches that had a history of problems were removed from K-Area and sent to SRL for inclusion in this study the week after the original seven assemblies were examined, bringing the total of latch assemblies discussed in this report to twenty one. Results of the examination of the K-Area latch that initiated this study is not included in this report.

  7. CI Slide: calibration slide for quantitative microscopy imaging in absorbance

    NASA Astrophysics Data System (ADS)

    Sheikhzadeh, Fahime; Ye, Qian; Zulkafly, Nasir; Carraro, Anita; Korbelic, Jagoda; Chen, Zhaoyang; Harrison, Alan; Follen, Michele; MacAulay, Calum; Ward, Rabab K.; Guillaud, Martial

    2014-03-01

    New imaging technologies are changing the field of digital pathology. This field faces numerous challenges and there is a pressing need for standardization, calibration protocols, quality control and quantitative assessment. We have designed a new calibration imaging slide (Cancer Imaging Slide), specifically to measure the characteristics of old or new imaging systems or scanners. The layout of the slide consists of 138 boxes with the side length of 1.6 mm, containing objects of known morphologic and photometric characteristics. Among them, 112 boxes contain different permutations of circles, ovals, and squares. The circles have different radii, radius/pitch ratios and step transmissions. The ovals have different sizes and orientations. The squares are consistent in size and orientation but have different step transmission values. Also, 16 boxes contain three resolution test targets: crosses, USAF target and Siemens star. The last 10 boxes are blank boxes with different transmission values. Four slides were scanned and imaged on one commercial whole-slide scanner and one high resolution imaging system. After segmenting the images, about 200 features (photometric, morphologic and architectural) were measured with our in-house image processing software. The objective of the project is to develop a statistical process control using this new slide. In this paper, we describe the characteristics of the slide and present our preliminary results.

  8. Miniature High-Force, Long-Stroke SMA Linear Actuators

    NASA Technical Reports Server (NTRS)

    Cummin, Mark A.; Donakowski, William; Cohen, Howard

    2008-01-01

    at greater cycle speeds, and have stronger housings that can withstand greater externally applied forces and impacts. The main novel features of the improved SMA actuators are the following: 1) The ends of the wires are anchored in compact crimps made from short steel tubes. Each wire end is inserted in a tube, the tube is flattened between planar jaws to make the tube grip the wire, the tube is compressed to a slight U-cross-section deformation to strengthen the grip, then the crimp is welded onto one of the actuator stages. The pull strength of a typical crimp is about 125 N -- comparable to the strength of the SMA wire and greater than the typical pull strengths of wire-end anchors in prior SMA actuators. Greater pull strength is one of the keys to achievement of higher actuation force; 2) For greater strength and resistance to impacts, housings are milled from aluminum instead of being made from polymers. Each housing is made from two pieces in a clamshell configuration. The pieces are anodized to reduce sliding friction; 3) Stages are made stronger (to bear greater compression loads without excessive flexing) by making them from steel sheets thicker than those used in prior SMA actuators. The stages contain recessed pockets to accommodate the crimps. Recessing the pockets helps to keep overall dimensions as small as possible; and, 4) UHT SMA wires are used to satisfy the higher-speed/higher-temperature requirement.

  9. 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.

  10. Designing light responsive bistable arches for rapid, remotely triggered actuation

    NASA Astrophysics Data System (ADS)

    Smith, Matthew L.; Shankar, M. Ravi; Backman, Ryan; Tondiglia, Vincent P.; Lee, Kyung Min; McConney, Michael E.; Wang, David H.; Tan, Loon-Seng; White, Timothy J.

    2014-03-01

    Light responsive azobenzene functionalized polymer networks enjoy several advantages as actuator candidates including the ability to be remotely triggered and the capacity for highly tunable control via light intensity, polarization, wavelength and material alignments. One signi cant challenge hindering these materials from being employed in applications is their often relatively slow actuation rates and low power densities, especially in the absence of photo-thermal e ects. One well known strategy employed in nature for increasing actuation rate and power output is the storage and quick release of elastic energy (e.g., the Venus ytrap). Using nature as inspiration we have conducted a series of experiments and developed an equilibrium mechanics model for investigating remotely triggered snap-through of bistable light responsive arches made from glassy azobenzene functionalized polymers. After brie y discussing experimental observations we consider in detail a geometrically exact, planar rod model of photomechanical snap-through. Theoretical energy release characteristics and unique strain eld pro les provide insight toward design strategies for improved actuator performance. The bistable light responsive arches presented here are potentially a powerful option for remotely triggered, rapid motion from apparently passive structures in applications such as binary optical switches and positioners, surfaces with morphing topologies, and impulse locomotion in micro or millimeter scale robotics.

  11. Strain actuated aeroelastic control

    NASA Technical Reports Server (NTRS)

    Lazarus, Kenneth B.

    1992-01-01

    Viewgraphs on strain actuated aeroelastic control are presented. Topics covered include: structural and aerodynamic modeling; control law design methodology; system block diagram; adaptive wing test article; bench-top experiments; bench-top disturbance rejection: open and closed loop response; bench-top disturbance rejection: state cost versus control cost; wind tunnel experiments; wind tunnel gust alleviation: open and closed loop response at 60 mph; wind tunnel gust alleviation: state cost versus control cost at 60 mph; wind tunnel command following: open and closed loop error at 60 mph; wind tunnel flutter suppression: open loop flutter speed; and wind tunnel flutter suppression: closed loop state cost curves.

  12. Compact valve actuation mechanism

    NASA Technical Reports Server (NTRS)

    Brogdon, James William (Inventor); Gill, David Keith (Inventor)

    2000-01-01

    A valve actuation device. The device may include a free floating valve bridge movably supported within a cavity in the engine housing. The bridge may be provided with a cavity and an orifice arrangement for pumping gases entrained with lubricating fluid toward the piston stems as the bridge reciprocates back and forth. The device may also include a rocker arm that has a U-shaped cross-sectional shape for receiving at least a portion of the valve bridge, valve stem valve spring and spring retainer therein. The rocker arm may be provided with lubrication passages for directing lubrication to the point wherein it is pivotally affixed to the engine housing.

  13. Piezoelectric actuated gimbal

    DOEpatents

    Tschaggeny, Charles W.; Jones, Warren F.; Bamberg, Eberhard

    2011-09-13

    A gimbal is described and which includes a fixed base member defining an axis of rotation; a second member concentrically oriented relative to the axis of rotation; a linear actuator oriented in immediate, adjoining force transmitting relation relative to the base member or to the second member, and which applies force along a linear axis which is tangential to the axis of rotation so as to cause the second member to rotate coaxially relative to the fixed base member; and an object of interest mounted to the second member such that the object of interest is selectively moved relative to the base member about the axis of rotation.

  14. Nature-inspired polymer actuators for micro-fluidic mixing.

    NASA Astrophysics Data System (ADS)

    den Toonder, Jaap M. J.; Bos, Femke; de Goede, Judith; Anderson, Patrick

    2007-11-01

    One particular micro-fluidics manipulation mechanism ``designed'' by nature is that due to a covering of beating cilia over the external surface of micro-organisms (e.g. Paramecium). A cilium can be viewed as a small hair or flexible rod (in protozoa: typical length 10 microns and diameter 0.1 microns) which is attached to the surface. We have developed polymer micro-actuators, made with standard micro-technology processing, which respond to an applied electrical or magnetic field by changing their shape. The shape and size of the polymer actuators mimics that of cilia occurring in nature. Flow visualization experiments show that the cilia can generate substantial fluid velocities, in the order of 1 mm/s. In addition, using specially designed geometrical configurations of the cilia, very efficient mixing is obtained. Since the artificial cilia can be actively controlled using electrical signals, they have exciting applications in micro-fluidic devices.

  15. Sliding mode control of electromagnetic tethered satellite formation

    NASA Astrophysics Data System (ADS)

    Hallaj, Mohammad Amin Alandi; Assadian, Nima

    2016-08-01

    This paper investigates the control of tethered satellite formation actuated by electromagnetic dipoles and reaction wheels using the robust sliding mode control technique. Generating electromagnetic forces and moments by electric current coils provides an attractive control actuation alternative for tethered satellite system due to the advantages of no propellant consumption and no obligatory rotational motion. Based on a dumbbell model of tethered satellite in which the flexibility and mass of the tether is neglected, the equations of motion in Cartesian coordinate are derived. In this model, the J2 perturbation is taken into account. The far-field and mid-field models of electromagnetic forces and moments of two satellites on each other and the effect of the Earth's magnetic field are presented. A robust sliding mode controller is designed for precise trajectory tracking purposes and to deal with the electromagnetic force and moment uncertainties and external disturbances due to the Earth's gravitational and magnetic fields inaccuracy. Numerical simulation results are presented to validate the effectiveness of the developed controller and its superiority over the linear controller.

  16. Robotic Arm Actuated by Electroactie Polymers

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Y.; Xue, T.; Shaninpoor, M.; Simpson, J. O.; Smith, J.

    1998-01-01

    Actuators are used for many planetary and space applications. To meet the NASA goal to reduce the actuators size, mass, cost and power consumption, electroactie polymers (EAP) are being developed to induce large bending and longitudinal actuation strains.

  17. Actuator operated microvalves

    NASA Technical Reports Server (NTRS)

    Okojie, Robert S. (Inventor)

    2008-01-01

    An actuator operated microvalve and the method of making same is disclosed and claimed. The microvalve comprises a SiC housing which includes a first lower portion and a second upper portion. The lower portion of the SiC housing includes a passageway therethrough, a microvalve seat, and a moveable SiC diaphragm. The SiC diaphragm includes a centrally located boss and radially extending corrugations which may be sinusoidally shaped. The boss of the SiC diaphragm moves and modulates in a range of positions between a closed position wherein the boss interengages said microvalve seat prohibiting communication of fluid through the passageway and a fully open position when the boss is spaced apart from the seat at its maximum permitting communication of fluid through said passageway. The actuator includes a SiC top plate affixed to the boss of the diaphragm and a first electrode and the second upper portion of the SiC housing further includes a second electrode.

  18. Adaptive sliding mode dynamic controller with integrator in the loop for nonholonomic wheeled mobile robot trajectory tracking

    NASA Astrophysics Data System (ADS)

    Asif, Muhammad; Junaid Khan, Muhammad; Cai, Ning

    2014-05-01

    In this paper, novel adaptive sliding mode dynamic controller with integrator in the loop is proposed for nonholonomic wheeled mobile robot (WMR). The modified kinematics controller is used to generate kinematics velocities of WMR which are subsequently used as the input to adaptive dynamic controller. Actuator dynamics are also derived to generate actuator voltage of WMR through torque and velocity vectors. Stability of both kinematics and dynamic controller is presented using Lyapunov stability analysis. The proposed scheme is verified and validated using computer simulations for tracking the desired trajectory of WMR. The performance of proposed scheme is compared with standard backstepping kinematics controller and classical sliding mode control. In addition, the performance is further compared with standard backstepping kinematics controller with adaptive sliding mode controller without integrator. It is shown that the proposed scheme exhibits zero steady state error, fast error convergence and robustness in the presence of continuous disturbances and uncertainties.

  19. Actuated Hybrid Mirror Telescope

    NASA Technical Reports Server (NTRS)

    Hickey, Gregory; Redding, David; Lowman, Andrew; Cohen, David; Ohara, Catherine

    2005-01-01

    The figure depicts the planned Actuated Hybrid Mirror Telescope (AHMT), which is intended to demonstrate a new approach to the design and construction of wide-aperture spaceborne telescopes for astronomy and Earth science. This technology is also appropriate for Earth-based telescopes. The new approach can be broadly summarized as using advanced lightweight mirrors that can be manufactured rapidly at relatively low cost. More specifically, it is planned to use precise replicated metallic nanolaminate mirrors to obtain the required high-quality optical finishes. Lightweight, dimensionally stable silicon carbide (SiC) structures will support the nanolaminate mirrors in the required surface figures. To enable diffraction- limited telescope performance, errors in surface figures will be corrected by use of mirror-shape-control actuators that will be energized, as needed, by a wave-front-sensing and control system. The concepts of nanolaminate materials and mirrors made from nanolaminate materials were discussed in several previous NASA Tech Briefs articles. Nanolaminates constitute a relatively new class of materials that can approach theoretical limits of stiffness and strength. Nanolaminate mirrors are synthesized by magnetron sputter deposition of metallic alloys and/or compounds on optically precise master surfaces to obtain optical-quality reflector surfaces backed by thin shell structures. As an integral part of the deposition process, a layer of gold that will constitute the reflective surface layer is deposited first, eliminating the need for a subsequent and separate reflective-coating process. The crystallographic textures of the nanolaminate will be controlled to optimize the performance of the mirror. The entire deposition process for making a nanolaminate mirror takes less than 100 hours, regardless of the mirror diameter. Each nanolaminate mirror will be bonded to its lightweight SiC supporting structure. The lightweight nanolaminate mirrors and Si

  20. Bi-stable optical actuator

    DOEpatents

    Holdener, Fred R.; Boyd, Robert D.

    2000-01-01

    The present invention is a bi-stable optical actuator device that is depowered in both stable positions. A bearing is used to transfer motion and smoothly transition from one state to another. The optical actuator device may be maintained in a stable position either by gravity or a restraining device.

  1. 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.

  2. 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.

  3. Fiber optic laser rod

    DOEpatents

    Erickson, G.F.

    1988-04-13

    A laser rod is formed from a plurality of optical fibers, each forming an individual laser. Synchronization of the individual fiber lasers is obtained by evanescent wave coupling between adjacent optical fiber cores. The fiber cores are dye-doped and spaced at a distance appropriate for evanescent wave coupling at the wavelength of the selected dye. An interstitial material having an index of refraction lower than that of the fiber core provides the optical isolation for effective lasing action while maintaining the cores at the appropriate coupling distance. 2 figs.

  4. Actuator-valve interface optimization

    SciTech Connect

    Burchett, O.L.; Jones, R.L.

    1986-01-01

    A computer code, Actuator Valve Response (AVR), has been developed to optimize the explosive actuator-valve interface parameters so that the valve plunger velocity is at a maximum when the plunger reaches the valve tubes. The code considers three forces to act on the valve plunger before the plunger reaches the valve tubes. These are the pressure force produced by the actuator, the shear force necessary to shear the seal disks on the actuator and the valve plunger, and the friction force caused by friction between the plunger and the plunger bore. The three forces are modeled by expressions that are explicitly functions of the plunger displacement. A particular actuator-valve combination was analyzed with the computer code AVR with four different combinations of valve plunger seal disk shear strength and initial friction force. (LEW)

  5. Reactor control rod timing system

    DOEpatents

    Wu, Peter T. K.

    1982-01-01

    A fluid driven jet-edge whistle timing system for control rods of a nuclear reactor for producing real-time detection of the timing of each control rod in its scram operation. An important parameter in reactor safety, particularly for liquid metal fast breeder reactors (LMFBR), is the time deviation between the time the control rod is released and the time the rod actually reaches the down position. The whistle has a nearly pure tone signal with center frequency (above 100 kHz) far above the frequency band in which the energy of the background noise is concentrated. Each control rod can be fitted with a whistle with a different frequency so that there is no ambiguity in differentiating the signal from each control rod.

  6. Restoration of Vision with Ectopic Expression of Human Rod Opsin.

    PubMed

    Cehajic-Kapetanovic, Jasmina; Eleftheriou, Cyril; Allen, Annette E; Milosavljevic, Nina; Pienaar, Abigail; Bedford, Robert; Davis, Katherine E; Bishop, Paul N; Lucas, Robert J

    2015-08-17

    Many retinal dystrophies result in photoreceptor loss, but the inner retinal neurons can survive, making them potentially amenable to emerging optogenetic therapies. Here, we show that ectopically expressed human rod opsin, driven by either a non-selective or ON-bipolar cell-specific promoter, can function outside native photoreceptors and restore visual function in a mouse model of advanced retinal degeneration. Electrophysiological recordings from retinal explants and the visual thalamus revealed changes in firing (increases and decreases) induced by simple light pulses, luminance increases, and naturalistic movies in treated mice. These responses could be elicited at light intensities within the physiological range and substantially below those required by other optogenetic strategies. Mice with rod opsin expression driven by the ON-bipolar specific promoter displayed behavioral responses to increases in luminance, flicker, coarse spatial patterns, and elements of a natural movie at levels of contrast and illuminance (≈50-100 lux) typical of natural indoor environments. These data reveal that virally mediated ectopic expression of human rod opsin can restore vision under natural viewing conditions and at moderate light intensities. Given the inherent advantages in employing a human protein, the simplicity of this intervention, and the quality of vision restored, we suggest that rod opsin merits consideration as an optogenetic actuator for treating patients with advanced retinal degeneration. PMID:26234216

  7. Restoration of Vision with Ectopic Expression of Human Rod Opsin

    PubMed Central

    Cehajic-Kapetanovic, Jasmina; Eleftheriou, Cyril; Allen, Annette E.; Milosavljevic, Nina; Pienaar, Abigail; Bedford, Robert; Davis, Katherine E.; Bishop, Paul N.; Lucas, Robert J.

    2015-01-01

    Summary Many retinal dystrophies result in photoreceptor loss, but the inner retinal neurons can survive, making them potentially amenable to emerging optogenetic therapies. Here, we show that ectopically expressed human rod opsin, driven by either a non-selective or ON-bipolar cell-specific promoter, can function outside native photoreceptors and restore visual function in a mouse model of advanced retinal degeneration. Electrophysiological recordings from retinal explants and the visual thalamus revealed changes in firing (increases and decreases) induced by simple light pulses, luminance increases, and naturalistic movies in treated mice. These responses could be elicited at light intensities within the physiological range and substantially below those required by other optogenetic strategies. Mice with rod opsin expression driven by the ON-bipolar specific promoter displayed behavioral responses to increases in luminance, flicker, coarse spatial patterns, and elements of a natural movie at levels of contrast and illuminance (≈50–100 lux) typical of natural indoor environments. These data reveal that virally mediated ectopic expression of human rod opsin can restore vision under natural viewing conditions and at moderate light intensities. Given the inherent advantages in employing a human protein, the simplicity of this intervention, and the quality of vision restored, we suggest that rod opsin merits consideration as an optogenetic actuator for treating patients with advanced retinal degeneration. PMID:26234216

  8. Making Highly Pure Glass Rods

    NASA Technical Reports Server (NTRS)

    Naumann, R. J.

    1986-01-01

    Proposed quasi-containerless method for making glass rods or fibers minimizes contact between processing equipment and product. Method allows greater range of product sizes and shapes than achieved in experiments on containerless processing. Molten zone established in polycrystalline rod. Furnace sections separated, and glass rod solidifies between them. Clamp supports solid glass as it grows in length. Pulling clamp rapidly away from melt draws glass fiber. Fiber diameter controlled by adjustment of pulling rate.

  9. TECHNICAL NOTE: Characteristic analysis of an ultrasonic micromotor using a 3 mm diameter piezoelectric rod

    NASA Astrophysics Data System (ADS)

    Chu, Xiangcheng; Yan, Li; Li, Longtu

    2004-04-01

    Smart systems and devices generally use certain microstructures, e.g. rod- and strip-shaped structures. In this paper, a miniaturized piezoelectric rod is analysed using the finite element method (FEM) and a laser scanning vibrometer (LSV). The effects of some factors, including the detailed structure, material parameters and input voltage, on the resonant frequencies and vibration behaviors of a piezoelectric rod are studied. On the basis of experimental results, the vibration modes of the piezoelectric rod can be made available for use in fabricating an ultrasonic micromotor or piezoelectric actuators of other types. The prototype motor fabricated here has a maximum output torque of 410 µN m for a stainless steel stator and 360 µN m for a copper stator. This article was originally published in 2003 by the Israel Academy of Sciences and Humanities in the framework of its Albert Einstein Memorial Lectures series. Reprinted by permission of the Israel Academy of Sciences and Humanities.

  10. Piston and connecting rod assembly

    NASA Technical Reports Server (NTRS)

    Brogdon, James William (Inventor); Gill, David Keith (Inventor); Chatten, John K. (Inventor)

    2001-01-01

    A piston and connecting rod assembly includes a piston crown, a piston skirt, a connecting rod, and a bearing insert. The piston skirt is a component separate from the piston crown and is connected to the piston crown to provide a piston body. The bearing insert is a component separate from the piston crown and the piston skirt and is fixedly disposed within the piston body. A bearing surface of a connecting rod contacts the bearing insert to thereby movably associate the connecting rod and the piston body.

  11. Sliding-gate valve

    DOEpatents

    Usnick, George B.; Ward, Gene T.; Blair, Henry O.; Roberts, James W.; Warner, Terry N.

    1979-01-01

    This invention is a novel valve of the slidable-gate type. The valve is designed especially for long-term use with highly abrasive slurries. The sealing surfaces of the gate are shielded by the valve seats when the valve is fully open or closed, and the gate-to-seat clearance is swept with an inflowing purge gas while the gate is in transit. A preferred form of the valve includes an annular valve body containing an annular seat assembly defining a flow channel. The seat assembly comprises a first seat ring which is slidably and sealably mounted in the body, and a second seat ring which is tightly fitted in the body. These rings cooperatively define an annular gap which, together with passages in the valve body, forms a guideway extending normal to the channel. A plate-type gate is mounted for reciprocation in the guideway between positions where a portion of the plate closes the channel and where a circular aperture in the gate is in register with the channel. The valve casing includes opposed chambers which extend outwardly from the body along the axis of the guideway to accommodate the end portions of the gate. The chambers are sealed from atmosphere; when the gate is in transit, purge gas is admitted to the chambers and flows inwardly through the gate-to-seat-ring, clearance, minimizing buildup of process solids therein. A shaft reciprocated by an external actuator extends into one of the sealed chambers through a shaft seal and is coupled to an end of the gate. Means are provided for adjusting the clearance between the first seat ring and the gate while the valve is in service.

  12. Electromagnetic variable degrees of freedom actuator systems and methods

    DOEpatents

    Montesanti, Richard C.; Trumper, David L.; Kirtley, Jr., James L.

    2009-02-17

    The present invention provides a variable reluctance actuator system and method that can be adapted for simultaneous rotation and translation of a moving element by applying a normal-direction magnetic flux on the moving element. In a beneficial example arrangement, the moving element includes a swing arm that carries a cutting tool at a set radius from an axis of rotation so as to produce a rotary fast tool servo that provides a tool motion in a direction substantially parallel to the surface-normal of a workpiece at the point of contact between the cutting tool and workpiece. An actuator rotates a swing arm such that a cutting tool moves toward and away from a mounted rotating workpiece in a controlled manner in order to machine the workpiece. Position sensors provide rotation and displacement information for a swing arm to a control system. A control system commands and coordinates motion of the fast tool servo with the motion of a spindle, rotating table, cross-feed slide, and in feed slide of a precision lathe.

  13. Electrically controlled polymeric gel actuators

    DOEpatents

    Adolf, Douglas B.; Shahinpoor, Mohsen; Segalman, Daniel J.; Witkowski, Walter R.

    1993-01-01

    Electrically controlled polymeric gel actuators or synthetic muscles capable of undergoing substantial expansion and contraction when subjected to changing pH environments, temperature, or solvent. The actuators employ compliant containers for the gels and their solvents. The gels employed may be cylindrical electromechanical gel fibers such as polyacrylamide fibers or a mixture of poly vinyl alcohol-polyacrylic acid arranged in a parallel aggregate and contained in an electrolytic solvent bath such as salt water. The invention includes smart, electrically activated devices exploiting this phenomenon. These devices are capable of being manipulated via active computer control as large displacement actuators for use in adaptive structure such as robots.

  14. Electrically controlled polymeric gel actuators

    DOEpatents

    Adolf, D.B.; Shahinpoor, M.; Segalman, D.J.; Witkowski, W.R.

    1993-10-05

    Electrically controlled polymeric gel actuators or synthetic muscles are described capable of undergoing substantial expansion and contraction when subjected to changing pH environments, temperature, or solvent. The actuators employ compliant containers for the gels and their solvents. The gels employed may be cylindrical electromechanical gel fibers such as polyacrylamide fibers or a mixture of poly vinyl alcohol-polyacrylic acid arranged in a parallel aggregate and contained in an electrolytic solvent bath such as salt water. The invention includes smart, electrically activated devices exploiting this phenomenon. These devices are capable of being manipulated via active computer control as large displacement actuators for use in adaptive structure such as robots. 11 figures.

  15. Gear-Driven Turnbuckle Actuator

    NASA Technical Reports Server (NTRS)

    Rivera, Ricky N.

    2010-01-01

    This actuator design allows the extension and contraction of turnbuckle assemblies. It can be operated manually or remotely, and is extremely compact. It is ideal for turnbuckles that are hard to reach by conventional tools. The tool assembly design solves the problem of making accurate adjustments to the variable geometry guide vanes without having to remove and reinstall the actuator system back on the engine. The actuator does this easily by adjusting the length of the turnbuckles while they are still attached to the engine.

  16. Composite Lightning Rods for Aircraft

    NASA Technical Reports Server (NTRS)

    Bryan, Charles F., Jr.

    1986-01-01

    Composite, lightweight sacrificial tip with graphite designed reduces lightning-strike damage to composite parts of aircraft and dissipates harmful electrical energy. Device consists of slender composite rod fabricated from highly-conductive unidirectional reinforcing fibers in matrix material. Rods strategically installed in trailing edges of aircraft wings, tails, winglets, control surfaces, and rearward-most portion of aft fuselage.

  17. Rod Climbing of Suspensions

    NASA Astrophysics Data System (ADS)

    Guo, Youjing; Wang, Xiaorong

    We wish to report an unexpected effect observed for particle suspensions sucked to pass through a vertical pipe. Above a critical concentration, the suspension on the outside of the pipe may climb along the outside wall of the pipe and then display a surprising rod-climbing effect. Our study shows that the phenomenon is influenced mainly by the suspension composition, the pipe dimension and the suction speed. The effects of the pipe materials of different kinds are negligible. Increasing the suction force and the concentration increases the climbing height. Increasing the pipe diameter and wall thickness reduces the climbing effect. This behavior may be relevant to that the suspensions of the type described are all displaying markedly shear-thickening.

  18. Enzyme actuated bioresponsive hydrogels

    NASA Astrophysics Data System (ADS)

    Wilson, Andrew Nolan

    Bioresponsive hydrogels are emerging with technological significance in targeted drug delivery, biosensors and regenerative medicine. Conferred with the ability to respond to specific biologically derived stimuli, the design challenge is in effectively linking the conferred biospecificity with an engineered response tailored to the needs of a particular application. Moreover, the fundamental phenomena governing the response must support an appropriate dynamic range and limit of detection. The design of these systems is inherently complicated due to the high interdependency of the governing phenomena that guide the sensing, transduction, and the actuation response of hydrogels. To investigate the dynamics of these materials, model systems may be used which seek to interrogate the system dynamics by uni-variable experimentation and limit confounding phenomena such as: polymer-solute interactions, polymer swelling dynamics and biomolecular reaction-diffusion concerns. To this end, a model system, alpha-chymotrypsin (Cht) (a protease) and a cleavable peptide-chromogen (pro-drug) covalently incorporated into a hydrogel, was investigated to understand the mechanisms of covalent loading and release by enzymatic cleavage in bio-responsive delivery systems. Using EDC and Sulfo-NHS, terminal carboxyl groups of N-succinyl-Ala-Ala-Pro-Phe p-nitroanilide, a cleavable chromogen, were conjugated to primary amines of a hydrated poly(HEMA)-based hydrogel. Hydrogel discs were incubated in buffered Cht causing enzyme-mediated cleavage of the peptide and concomitant release of the chromophore for monitoring. To investigate substrate loading and the effects of hydrogel morphology on the system, the concentration of the amino groups (5, 10, 20, and 30 mol%) and the cross-linked density (1, 5, 7, 9 and 12 mol%) were independently varied. Loading-Release Efficiency of the chromogen was shown to exhibit a positive relation to increasing amino groups (AEMA). The release rates demonstrated a

  19. Variable Valve Actuation

    SciTech Connect

    Jeffrey Gutterman; A. J. Lasley

    2008-08-31

    Many approaches exist to enable advanced mode, low temperature combustion systems for diesel engines - such as premixed charge compression ignition (PCCI), Homogeneous Charge Compression Ignition (HCCI) or other HCCI-like combustion modes. The fuel properties and the quantity, distribution and temperature profile of air, fuel and residual fraction in the cylinder can have a marked effect on the heat release rate and combustion phasing. Figure 1 shows that a systems approach is required for HCCI-like combustion. While the exact requirements remain unclear (and will vary depending on fuel, engine size and application), some form of substantially variable valve actuation is a likely element in such a system. Variable valve actuation, for both intake and exhaust valve events, is a potent tool for controlling the parameters that are critical to HCCI-like combustion and expanding its operational range. Additionally, VVA can be used to optimize the combustion process as well as exhaust temperatures and impact the after treatment system requirements and its associated cost. Delphi Corporation has major manufacturing and product development and applied R&D expertise in the valve train area. Historical R&D experience includes the development of fully variable electro-hydraulic valve train on research engines as well as several generations of mechanical VVA for gasoline systems. This experience has enabled us to evaluate various implementations and determine the strengths and weaknesses of each. While a fully variable electro-hydraulic valve train system might be the 'ideal' solution technically for maximum flexibility in the timing and control of the valve events, its complexity, associated costs, and high power consumption make its implementation on low cost high volume applications unlikely. Conversely, a simple mechanical system might be a low cost solution but not deliver the flexibility required for HCCI operation. After modeling more than 200 variations of the

  20. Firewater system inadvertent actuation frequencies

    SciTech Connect

    Schroeder, J.A.; Eide, S.A.

    1993-04-01

    This paper presents some recommended generic values for fire protection system inadvertent actuation frequencies. The frequencies are based on actual data from Department of Energy and commercial reactor plant facilities.

  1. Firewater system inadvertent actuation frequencies

    SciTech Connect

    Schroeder, J.A. ); Eide, S.A. )

    1993-01-01

    This paper presents some recommended generic values for fire protection system inadvertent actuation frequencies. The frequencies are based on actual data from Department of Energy and commercial reactor plant facilities.

  2. 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.

  3. Sensors, actuators, and smart materials

    NASA Astrophysics Data System (ADS)

    Troiler-McKinstry, S.; Newnham, R. E.

    1993-04-01

    Electroceramic materials are presently noted to have a wide array of sensing and actuating functions which can be incorporated into smart-material designs. The sensor types extend to temperature, piezoelectricity and piezoresistivity, and the presence of oxygen. Attention is given to the prospects for developing composite smart materials that encompass various sensing and actuating functions; these may ultimately reach a level of complexity and sophistication that may be termed 'biomimetric' in its approximation to the functions of the living tissues of organisms.

  4. Fail-safe electric actuator

    SciTech Connect

    Wright, J.J.

    1988-07-19

    In combination with a control mechanism characterized by the ability to be moved from inoperative to operative position and back, a fail-safe actuator device for automatically returning the control mechanism to inoperative position when interruption of electric power occurs is described which comprises: a fluid-driven vaned torque actuator: electric-motor-driven fluid power means for operating the torque actuator; electrically operated valve means for controlling the power fluid flow between the torque actuator and the fluid power generating means; at least one shaft projecting from the torque actuator; coupling means for operatively connecting the shaft to the control mechanism to be operated by the failsafe actuator device; reversible means for storing energy, the reversible means being operatively connected to the shaft; a limit-switch operating cam mounted on and rotable with the shaft; a limit switch positioned for activation by the limit-switch operating cam; and electric circuitry means for interconnecting the motordriven fluid power generating means, the valve means, and the limit switch.

  5. Thermally actuated piston micromirror arrays

    NASA Astrophysics Data System (ADS)

    Cowan, William D.; Bright, Victor M.

    1997-07-01

    This paper reports design and characterization testing of thermally actuated piston micromirror arrays. The micromirrors were fabricated in the DARPA-sponsored MUMPs polysilicon surface micromachining process. The power averaging characteristic of thermal actuation is exploited in a novel line addressing scheme which reduces wiring for an n2 array to 2n wires. Mirror deflections were measured with a microscope laser interferometer system equipped with a vacuum chamber. Data presented includes device uniformity, frequency response, and deflection versus drive power for varied ambient pressure. Initial test results confirm that thermally actuated piston micromirrors offer several advantages over more common electrostatic designs. Thermally actuated micromirrors offer greater deflections at drive voltages compatible with CMOS circuitry. Measured thermal piston micromirror deflection versus drive voltage is nonlinear, but does not exhibit the 'snap through instability' characteristic of electrostatic devices. Operation of thermally actuated devices in rarefied ambient significantly decreases power dissipation. For a given deflection range, the power reduction facilitated by vacuum operation makes large arrays feasible. Frequency response of thermally actuated devices is limited by the ability of the device to dissipate heat, but operation at 1 kHz rates is feasible.

  6. Explosive actuated valve

    DOEpatents

    Byrne, Kenneth G.

    1983-01-01

    1. A device of the character described comprising the combination of a housing having an elongate bore and including a shoulder extending inwardly into said bore, a single elongate movable plunger disposed in said bore including an outwardly extending flange adjacent one end thereof overlying said shoulder, normally open conduit means having an inlet and an outlet perpendicularly piercing said housing intermediate said shoulder and said flange and including an intermediate portion intersecting and normally openly communicating with said bore at said shoulder, normally closed conduit means piercing said housing and intersecting said bore at a location spaced from said normally open conduit means, said elongate plunger including a shearing edge adjacent the other end thereof normally disposed intermediate both of said conduit means and overlying a portion of said normally closed conduit means, a deformable member carried by said plunger intermediate said flange and said shoulder and normally spaced from and overlying the intermediate portion of said normally open conduit means, and means on the housing communicating with the bore to retain an explosive actuator for moving said plunger to force the deformable member against the shoulder and extrude a portion of the deformable member out of said bore into portions of the normally open conduit means for plugging the same and to effect the opening of said normally closed conduit means by the plunger shearing edge substantially concomitantly with the plugging of the normally open conduit means.

  7. Quick actuating closure

    NASA Technical Reports Server (NTRS)

    White, III, Dorsey E. (Inventor); Updike, deceased, Benjamin T. (Inventor); Allred, Johnny W. (Inventor)

    1989-01-01

    A quick actuating closure for a pressure vessel 80 in which a wedge ring 30 with a conical outer surface 31 is moved forward to force shear blocks 40, with conical inner surfaces 41, radially outward to lock an end closure plug 70 within an opening 81 in the pressure vessel 80. A seal ring 60 and a preload ramp 50 sit between the shear blocks 40 and the end closure plug 70 to provide a backup sealing capability. Conical surfaces 44 and 55 of the preload ramp 50 and the shear blocks 40 interact to force the seal ring 60 into shoulders 73 and 85 in the end closure plug 70 and opening 81 to form a tight seal. The end closure plug 70 is unlocked by moving the wedge ring 30 rearward, which causes T-bars 32 of the wedge ring 30 riding within T -slots 42 of the shear blocks 40 to force them radially inward. The end closure plug 70 is then removed, allowing access to the interior of the pressure vessel 80.

  8. Carbon nanotube array actuators

    NASA Astrophysics Data System (ADS)

    Geier, S.; Mahrholz, T.; Wierach, P.; Sinapius, M.

    2013-09-01

    Experimental investigations of highly vertically aligned carbon nanotubes (CNTs), also known as CNT-arrays, are the main focus of this paper. The free strain as result of an active material behavior is analyzed via a novel experimental setup. Previous test experiences of papers made of randomly oriented CNTs, also called Bucky-papers, reveal comparably low free strain. The anisotropy of aligned CNTs promises better performance. Via synthesis techniques like chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD), highly aligned arrays of multi-walled carbon nanotubes (MWCNTs) are synthesized. Two different types of CNT-arrays are analyzed, morphologically first, and optically tested for their active characteristics afterwards. One type of the analyzed arrays features tube lengths of 750-2000 μm with a large variety of diameters between 20 and 50 nm and a wave-like CNT-shape. The second type features a maximum, almost uniform, length of 12 μm and a constant diameter of 50 nm. Different CNT-lengths and array types are tested due to their active behavior. As result of the presented tests, it is reported that the quality of orientation is the most decisive property for excellent active behavior. Due to their alignment, CNT-arrays feature the opportunity to clarify the actuation mechanism of architectures made of CNTs.

  9. Multiple switch actuator

    DOEpatents

    Beyer, Edward T.

    1976-01-06

    The present invention relates to switches and switch actuating devices to be operated for purposes of arming a bomb or other missile as it is dropped or released from an aircraft. The particular bomb or missile in which this invention is applied is one in which there is a plurality of circuits which are to be armed by the closing of switches upon dropping or releasing of the bomb. The operation of the switches to closed position is normally accomplished by means of a pull-out wire; that is, a wire which is withdrawn from the bomb or missile at the time of release of the bomb, one end of the wire being attached to the aircraft. The conditions to be met are that the arming switches must be positively and surely maintained in open position until the bomb is released and the arming action is effected. The action of the pull-out wire in achieving the arming action must be sure and positive with minimum danger of malfunctioning, jamming or binding.

  10. Regenerative hyperpolarization in rods.

    PubMed Central

    Werblin, F S

    1975-01-01

    1. The electrical properties of the rods in Necturus maculosus were studied at the cell body and the outer segments in dark and light under current and voltage clamp with a pair of intracellular electrodes separated by about 1 mum. 2. The membrane resistance in the dark was voltage- and time-dependent both for the cell body and the outer segment. Slight depolarizations in the cell body reduced the slope resistance from 60 to 10 M omega with a time constant of about 1 sec. Polarization in either direction, at the outer segment, when greater than about 20 mV, reduced the slope resistance from 60 to 30 M omega. The dark potential in the cell body was typically -30 to -35 m V; at the outer segment it was typically only -10 to -15 mV. 3. The light-elicited voltage response in both the cell body and the outer segment was largest with the membrane near the dark potential level. In both regions, the response was reduced when the membrane was polarized in either direction. 4. Under voltage-clamp conditions, a reversal potential for the light response near + 10 mV was measured at the outer segment. At the cell body no reversal potential for the light response was measured; there the clamping current required during the light response was almost of the same magnitude at all potential levels. 5. When the membrane at the cell body was hyperpolarized in the dark under voltage clamp, a transient outward current, typically about one-half the magnitude of the initial inward clamping current was required to maintain the membrane at the clamped potential level. This outward current transient was associated with a decrease in membrane resistance with similar time course. The transient outward current reversed and became inward when the membrane was clamped to potentials more negative than -80 mV. Thus, the transient outward current appears to involve a transient activation initiated by hyperpolarization. I is regenerative in that it is initiated by hyperpolarization and tends to

  11. Status of rod consolidation, 1988

    SciTech Connect

    Bailey, W.J.

    1989-01-01

    It is estimated that the spent fuel storage pools at some domestic light-water reactors will run out of space before 2003, the year that the US Department of Energy currently predicts it will have a repository available. Of the methods being studied to alleviate the problem, rod consolidation is one of the leading candidates for achieving more efficient use of existing space in spent fuel storage pools. Rod consolidation involves mechanically removing all the fuel rods from the fuel assembly hardware (i.e., the structural components) and placing the fuel rods in a close-packed array in a canister without space grids. A typical goal of rod consolidation systems is to insert the fuel rods from two fuel assemblies into a canister that has the same exterior dimensions as one standard fuel assembly (i.e., to achieve a consolidation or compaction ratio of 2:1) and to compact the nonfuel-bearing structural components from those two fuel assemblies by a factor of 10 to 20. This report provides an overview of the current status of rod consolidation in the United States and a small amount of information on related activities in other countries. 85 refs., 36 figs., 5 tabs.

  12. Fast-Response-Time Shape-Memory-Effect Foam Actuators

    NASA Technical Reports Server (NTRS)

    Jardine, Peter

    2010-01-01

    the need for welding, adhesives, or mechanical crimping. Inexpensive net-shape processing was used, which reduces the cost of the actuator by over a factor of 10 over nonporous TiNi made by hot drawing of tube or electrical discharge machining. By forming the alloy as an open-celled foam, the surface area for heat transfer is dramatically increased, allowing for much faster response times. The technology also allows for netshape fabrication of the actuator, which allows for structural connections to be integrated into the actuator material, making these actuators significantly less expensive. Commercial applications include actuators for concepts such as the variable area chevron and nozzle in jet aircraft. Lightweight tube or rod components can be supplied to interested parties.

  13. Self-contained hybrid electro-hydraulic actuators using magnetostrictive and electrostrictive materials

    NASA Astrophysics Data System (ADS)

    Chaudhuri, Anirban

    Hybrid electro-hydraulic actuators using smart materials along with flow rectification have been widely reported in recent years. The basic operation of these actuators involves high frequency bidirectional operation of an active material that is converted into unidirectional fluid motion by a set of valves. While theoretically attractive, practical constraints limit the efficacy of the solid-fluid hybrid actuation approach. In particular, inertial loads, fluid viscosity and compressibility combine with loss mechanisms inherent in the active material to limit the effective bandwidth of the driving actuator and the total output power. A hybrid actuator was developed by using magnetostrictive TerFeNOL-D as the active driving element and hydraulic oil as the working fluid. Tests, both with and without an external load, were carried out to measure the unidirectional performance of the actuator at different pumping frequencies and operating conditions. The maximum no-load output velocity was 84 mm/s with a 51 mm long rod and 88 mm/s with a 102 mm long rod, both noted around 325 Hz pumping frequency, while the blocked force was close to 89 N. Dynamic tests were performed to analyze the axial vibration characteristics of the Terfenol-D rods and frequency responses of the magnetic circuits. A second prototype actuator employing the same actuation principle was then designed by using the electrostrictive material PMN-32%PT as the driving element. Tests were conducted to measure the actuator performance for varying electrical input conditions and fluid bias pressures. The peak output velocity obtained was 330 mm/s while the blocked force was 63 N. The maximum volume flow rate obtained with the PMN-based actuator was more than double that obtained from the Terfenol-D--based actuator. Theoretical modeling of the dynamics of the coupled structural-hydraulic system is extremely complex and several models have been proposed earlier. At high pumping frequencies, the fluid inertia

  14. Stable electroosmotically driven actuators

    NASA Astrophysics Data System (ADS)

    Sritharan, Deepa; Motsebo, Mylene; Tumbic, Julia; Smela, Elisabeth

    2013-04-01

    We have previously presented "nastic" actuators based on electroosmotic (EO) pumping of fluid in microchannels using high electric fields for potential application in soft robotics. In this work we address two challenges facing this technology: applying EO to meso-scale devices and the stability of the pumping fluid. The hydraulic pressure achieved by EO increases with as 1/d2, where d is the depth of the microchannel, but the flow rate (which determines the stroke and the speed) is proportional to nd, where n is the number of channels. Therefore to get high force and high stroke the device requires a large number of narrow channels, which is not readily achievable using standard microfabrication techniques. Furthermore, for soft robotics the structure must be soft. In this work we present a method of fabricating a three-dimensional porous elastomer to serve as the array of channels based on a sacrificial sugar scaffold. We demonstrate the concept by fabricating small pumps. The flexible devices were made from polydimethylsiloxane (PDMS) and comprise the 3D porous elastomer flanked on either side by reservoirs containing electrodes. The second issue addressed here involves the pumping fluid. Typically, water is used for EO, but water undergoes electrolysis even at low voltages. Since EO takes place at kV, these systems must be open to release the gases. We have recently reported that propylene carbonate (PC) is pumped at a comparable rate as water and is also stable for over 30 min at 8 kV. Here we show that PC is, however, degraded by moisture, so future EO systems must prevent water from reaching the PC.

  15. Preliminary study of lever-based optical driven micro-actuator

    NASA Astrophysics Data System (ADS)

    Lin, Chih-Lang; Li, Yi-Hsiung; Lin, Chin-Te; Chiang, Chia-Chin; Liu, Yi-Jui; Chung, Tien-Tung; Baldeck, Patrice L.

    2012-04-01

    This study presents a novel type of optically driven lever-based micro-actuator fabricated using two-photon polymerization 3D-microfabrication technique. The lever is composed of a beam, an arch, and a sphere. First, optical tweezers is applied on the spheres to demonstrate the actuation of the lever. A spring is jointed at the lever for verifying the induced forces. Under the dragging by laser focusing, the lever simultaneously turns and results a torque like a mechanical arm. Then, the demonstration of a photo-driven micro-transducer with a mechanical arm and a gear is preformed. The experimental result indicates that our design enables precise manipulation of the mirco-actuator by optical tweezers at micron scale. This study provides a possibility for driving micron-sized structured mechanisms, such as connecting rods, valves. It is expected to contribute on the investigation of "Lab-on-a-chip".

  16. Kinematics Analysis of the Parallel Mechanism with Vertically Fixed Linear Actuators

    NASA Astrophysics Data System (ADS)

    Masuda, Takanori; Fujiwara, Motoyoshi; Arai, Tatsuo

    A 6 degrees of freedom parallel mechanism actuated by vertically fixed linear actuators was developed for heavy material handling and machining. The mechanism allows easy trajectory generation, since the vertical arrangement of the linear actuators simplifies the caluculation of its inverse kinematics. This paper presents inverse kinematics and Jacobian matirix solutions. Way to avoid component interference, which is divided into three types, is proposed. The combination of design parameters is decided by comparing the characteristics of area of movement, resolution and velocity. The working space is then shown. The singularity is analyzed by evaluating determinants of the Jacobian matrix. Lengthening the connecting rods and limiting the range of the end effector rotational angles are effective in avoiding the singular configurations as well as interference. Finally, the developed prototype mechanism is introduced, and its application to tool positioning and machining is described.

  17. Preliminary study of lever-based optical driven micro-actuator

    NASA Astrophysics Data System (ADS)

    Lin, Chih-Lang; Li, Yi-Hsiung; Lin, Chin-Te; Chiang, Chia-Chin; Liu, Yi-Jui; Chung, Tien-Tung; Baldeck, Patrice L.

    2011-11-01

    This study presents a novel type of optically driven lever-based micro-actuator fabricated using two-photon polymerization 3D-microfabrication technique. The lever is composed of a beam, an arch, and a sphere. First, optical tweezers is applied on the spheres to demonstrate the actuation of the lever. A spring is jointed at the lever for verifying the induced forces. Under the dragging by laser focusing, the lever simultaneously turns and results a torque like a mechanical arm. Then, the demonstration of a photo-driven micro-transducer with a mechanical arm and a gear is preformed. The experimental result indicates that our design enables precise manipulation of the mirco-actuator by optical tweezers at micron scale. This study provides a possibility for driving micron-sized structured mechanisms, such as connecting rods, valves. It is expected to contribute on the investigation of "Lab-on-a-chip".

  18. Transparent acrylic enamel slide holograms

    NASA Astrophysics Data System (ADS)

    Ponce-Lee, E. L.; Olivares Pérez, A.; Ruiz-Limón, B.; Hernández-Garay, M. P.; Toxqui-López, S.

    2006-02-01

    We present holograms generated in a computer to an acrylic enamel slide (Comex (R)), getting phase holograms. The information in the mask is transferred to the material by temperature gradients generated by rubbing. The refraction index is transformed at each material point by the temperature changes, thus the film is recorded and developed by itself. this material can be used for soft lithography.

  19. Creating Slide Show Book Reports.

    ERIC Educational Resources Information Center

    Taylor, Harriet G.; Stuhlmann, Janice M.

    1995-01-01

    Describes the use of "Kid Pix 2" software by fourth grade students to develop slide-show book reports. Highlights include collaboration with education majors from Louisiana State University, changes in attitudes of the education major students and elementary students, and problems with navigation and disk space. (LRW)

  20. 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.

  1. 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…

  2. Hopf solitons and elastic rods

    SciTech Connect

    Harland, Derek; Sutcliffe, Paul; Speight, Martin

    2011-03-15

    Hopf solitons in the Skyrme-Faddeev model are stringlike topological solitons classified by the integer-valued Hopf charge. In this paper we introduce an approximate description of Hopf solitons in terms of elastic rods. The general form of the elastic rod energy is derived from the field theory energy and is found to be an extension of the classical Kirchhoff rod energy. Using a minimal extension of the Kirchhoff energy, it is shown that a simple elastic rod model can reproduce many of the qualitative features of Hopf solitons in the Skyrme-Faddeev model. Features that are captured by the model include the buckling of the charge three solution, the formation of links at charges five and six, and the minimal energy trefoil knot at charge seven.

  3. Cryogenic actuator for subnanometer positioning

    NASA Astrophysics Data System (ADS)

    Bree, B. v.; Janssen, H.; Paalvast, S.; Albers, R.

    2012-09-01

    This paper discusses the development, realization, and qualification of a positioning actuator concept specifically for cryogenic environments. Originally developed for quantum physics research, the actuator also has many applications in astronomic cryogenic instruments to position optical elements with nanometer level accuracy and stability. Typical applications include the correction of thermally induced position errors of optical components after cooling down from ambient to cryogenic temperatures or sample positioning in microscopes. The actuator is nicknamed the ‘PiezoKnob’ because it is piezo based and it is compatible with the typical manipulator knob often found in standard systems for optical benches, such as linear stages or tip/tilt lens holders. Actuation with high stiffness piezo elements enables the Piezoknob to deliver forces up to 50 Newton which allows relatively stiff guiding mechanisms or large pre-loads. The PiezoKnob has been qualified at 77 Kelvin and was shown to work down to 2 Kelvin. As part of the qualification program, the custom developed driving electronics and set point profile have been fine-tuned, by combing measurements with predictions from a dynamic model, thus maximizing efficiency and minimizing power dissipation. Furthermore, the actuator holds its position without power and thanks to its mechanical layout it is absolutely insensitive to drift of the piezo elements or the driving electronics.

  4. Temperature-memory polymer actuators

    PubMed Central

    Behl, Marc; Kratz, Karl; Noechel, Ulrich; Sauter, Tilman; Lendlein, Andreas

    2013-01-01

    Reading out the temperature-memory of polymers, which is their ability to remember the temperature where they were deformed recently, is thus far unavoidably linked to erasing this memory effect. Here temperature-memory polymer actuators (TMPAs) based on cross-linked copolymer networks exhibiting a broad melting temperature range (ΔTm) are presented, which are capable of a long-term temperature-memory enabling more than 250 cyclic thermally controlled actuations with almost constant performance. The characteristic actuation temperatures Tacts of TMPAs can be adjusted by a purely physical process, guiding a directed crystallization in a temperature range of up to 40 °C by variation of the parameter Tsep in a nearly linear correlation. The temperature Tsep divides ΔTm into an upper Tm range (T > Tsep) forming a reshapeable actuation geometry that determines the skeleton and a lower Tm range (T < Tsep) that enables the temperature-controlled bidirectional actuation by crystallization-induced elongation and melting-induced contraction. The macroscopic bidirectional shape changes in TMPAs could be correlated with changes in the nanostructure of the crystallizable domains as a result of in situ X-ray investigations. Potential applications of TMPAs include heat engines with adjustable rotation rate and active building facades with self-regulating sun protectors. PMID:23836673

  5. The LDCM actuator for vibration suppression

    NASA Technical Reports Server (NTRS)

    Ide, Eric N.; Lindner, Douglas K.

    1988-01-01

    A linear dc motor (LDCM) has been proposed as an actuator for the COFS I mast and the COFS program ground test Mini-Mast. The basic principles of operation of the LDCM as an actuator for vibration suppression in large flexible structures are reviewed. Because of force and stroke limitations, control loops are required to stabilize the actuator, which results in a non-standard actuator-plant configuration. A simulation model that includes LDCM actuator control loops and a finite element model of the Mast is described, with simulation results showing the excitation capability of the actuator.

  6. Nuclear design of Helical Cruciform Fuel rods

    SciTech Connect

    Shirvan, K.; Kazimi, M. S.

    2012-07-01

    In order to increase the power density of current and new light water reactor designs, the Helical Cruciform Fuel (HCF) rods are proposed. The HCF rods are equivalent to a cylindrical rod, with the fuel in a cruciform shaped, twisted axially. The HCF rods increase the surface area to volume ratio and inter-subchannel mixing behavior due to their cruciform and helical shapes, respectively. In a previous study, the HCF rods have shown the potential to up-rate existing PWRs by 50% and BWRs by 25%. However, HCF rods do display different neutronics modeling and performance. The cruciform cross section of HCF rods creates radially asymmetric heat generation and temperature distribution. The nominal HCF rod's beginning of life reactivity is reduced, compared to a cylindrical rod with the same fuel volume, by 500 pcm, due to increase in absorption in cladding. The rotation of these rods accounts for reactivity changes, which depends on the H/HM ratio of the pin cell. The HCF geometry shows large sensitivities to U{sup 235} or gadolinium enrichments compared to a cylindrical geometry. In addition, the gadolinium-containing HCF rods show a stronger effect on neighboring HCF rods than in case of cylindrical rods, depending on the orientation of the HCF rods. The helical geometry of the rods introduces axial shadowing of about 600 pcm, not seen in typical cylindrical rods. (authors)

  7. 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,…

  8. On-Line Retrieval of Clinical Slides.

    ERIC Educational Resources Information Center

    Milgrom, Linda

    The Physical Diagnosis Slide Bank, a collaborative project of the Universities of Washington, California at San Diego, and Arizona, utilizes an online interactive computer program to access a collection of over 2000 teaching clinical slides. Searchable data elements for each slide in the bank include subject descriptors (MeSH); accession number;…

  9. 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…

  10. 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,…

  11. Electromechanical propellant control system actuator

    NASA Technical Reports Server (NTRS)

    Myers, W. Neill; Weir, Rae Ann

    1990-01-01

    New control mechanism technologies are currently being sought to provide alternatives to hydraulic actuation systems. The Propulsion Laboratory at Marshall Space Flight Center (MSFC) is involved in the development of electromechanical actuators (EMA's) for this purpose. Through this effort, an in-house designed electromechanical propellant valve actuator has been assembled and is presently being evaluated. This evaluation will allow performance comparisons between EMA and hydraulics systems. The in-house design consists of the following hardware: a three-phase brushless motor, a harmonic drive, and an output spline which will mate with current Space Shuttle Main Engine (SSME) propellant control valves. A resolver and associated electronics supply position feedback for the EMA. System control is provided by a solid-state electronic controller and power supply. Frequency response testing has been performed with further testing planned as hardware and test facilities become available.

  12. A Parylene Bellows Electrochemical Actuator

    PubMed Central

    Li, Po-Ying; Sheybani, Roya; Gutierrez, Christian A.; Kuo, Jonathan T. W.; Meng, Ellis

    2011-01-01

    We present the first electrochemical actuator with Parylene bellows for large-deflection operation. The bellows diaphragm was fabricated using a polyethylene-glycol-based sacrificial molding technique followed by coating in Parylene C. Bellows were mechanically characterized and integrated with a pair of interdigitated electrodes to form an electrochemical actuator that is suitable for low-power pumping of fluids. Pump performance (gas generation rate and pump efficiency) was optimized through a careful examination of geometrical factors. Overall, a maximum pump efficiency of 90% was achieved in the case of electroplated electrodes, and a deflection of over 1.5 mm was demonstrated. Real-time wireless operation was achieved. The complete fabrication process and the materials used in this actuator are bio-compatible, which makes it suitable for biological and medical applications. PMID:21318081

  13. NEUTRONIC REACTOR CONTROL ROD DRIVE APPARATUS

    DOEpatents

    Oakes, L.C.; Walker, C.S.

    1959-12-15

    ABS>A suspension mechanism between a vertically movable nuclear reactor control rod and a rod extension, which also provides information for the operator or an automatic control signal, is described. A spring connects the rod extension to a drive shift. The extension of the spring indicates whether (1) the rod is at rest on the reactor, (2) the rod and extension are suspended, or (3) the extension alone is suspended, the spring controlling a 3-position electrical switch.

  14. Classical and higher-order sliding mode attitude control for launch vehicle systems

    NASA Astrophysics Data System (ADS)

    Stott, James Edward, Jr.

    In determining flight controls for launch vehicle systems, several things must be taken into account. Launch vehicle systems can be expendable or reusable, carry crew or cargo, etc. Each of these launch vehicles maneuvers through a wide range of flight conditions and different mission profiles. Crewed vehicles must adhere to human rating requirements which limit the angular rates. Reusable launch vehicle systems must take into account actuator saturation during entry. Wind disturbances and plant uncertainties are major perturbations to the nominal state of any launch vehicle. An ideal controller is one that is robust enough to handle these uncertainties and external disturbances with limited control authority. One major challenge that exists in the design of these vehicles is the updating of old autopilot technology to new robust designs while also taking into account the different type of launch vehicle system employed. Sliding mode control algorithms that are inherently robust to external disturbances and plant uncertainties are very good candidates for improving the robustness and accuracy of the flight control systems. This dissertation focuses on systematically studying and developing a 'toolbox' of classical and higher-order sliding mode attitude control algorithms for different types of launch vehicle systems operating in uncertain conditions, including model uncertainties, actuator malfunctions, and external perturbations such as wind gusts. The developed toolbox comprises of time-varying sliding variables, classical and higher-order sliding mode attitude control algorithms, and observer techniques that yield novel sliding mode attitude control architectures. The proposed control toolbox allows achieving even higher standards of performance, reliability, safety, operability, and cost for launch vehicles over the current state of the art. Case studies include controlling the X-33 and SLV-X Launch Vehicles studied under NASA's Space Launch Initiative (SLI

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

    SciTech Connect

    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.

  16. Fast-acting valve actuator

    DOEpatents

    Cho, Nakwon

    1980-01-01

    A fast-acting valve actuator utilizes a spring driven pneumatically loaded piston to drive a valve gate. Rapid exhaust of pressurized gas from the pneumatically loaded side of the piston facilitates an extremely rapid piston stroke. A flexible selector diaphragm opens and closes an exhaust port in response to pressure differentials created by energizing and de-energizing a solenoid which controls the pneumatic input to the actuator as well as selectively providing a venting action to one side of the selector diaphragm.

  17. Electrostatically actuatable light modulating device

    DOEpatents

    Koehler, Dale R.

    1991-01-01

    The electrostatically actuatable light modulator utilizes an opaque substrate plate patterned with an array of aperture cells, the cells comprised of physically positionable dielectric shutters and electrostatic actuators. With incorporation of a light source and a viewing screen, a projection display system is effected. Inclusion of a color filter array aligned with the aperture cells accomplishes a color display. The system is realized in terms of a silicon based manufacturing technology allowing fabrication of a high resolution capability in a physically small device which with the utilization of included magnification optics allows both large and small projection displays.

  18. 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.

  19. Miniature linear-to-rotary motion actuator

    NASA Technical Reports Server (NTRS)

    Sorokach, Michael R., Jr.

    1993-01-01

    A miniature hydraulic actuation system capable of converting linear actuator motion to control surface rotary motion has been designed for application to active controls on dynamic wind tunnel models. Due to space constraints and the torque requirements of an oscillating control surface at frequencies up to 50 Hertz, a new actuation system was developed to meet research objectives. This new actuation system was designed and developed to overcome the output torque limitations and fluid loss/sealing difficulties associated with an existing vane type actuator. Static control surface deflections and dynamic control surface oscillations through a given angle are provided by the actuation system. The actuator design has been incorporated into a transonic flutter model with an active trailing edge flap and two active spoilers. The model is scheduled for testing in the LaRC 16 Foot Transonic Dynamics Tunnel during Summer 1993. This paper will discuss the actuation system, its design, development difficulties, test results, and application to aerospace vehicles.

  20. New electrode materials for dielectric elastomer actuators

    NASA Astrophysics Data System (ADS)

    Yuan, Wei; Lam, Tuling; Biggs, James; Hu, Liangbing; Yu, Zhibin; Ha, Soonmok; Xi, Dongjuan; Senesky, Matthew K.; Grüner, George; Pei, Qibing

    2007-04-01

    Dielectric elastomer actuators exert strain due to an applied electric field. With advantageous properties such as high efficiency and their light weight, these actuators are attractive for a variety of applications ranging from biomimetic robots, medical prosthetics to conventional pumps and valves. The performance and reliability however, are limited by dielectric breakdown which occurs primarily from localized defects inherently present in the polymer film during actuation. These defects lead to electric arcing, causing a short circuit that shuts down the entire actuator and can lead to actuator failure at fields significantly lower than the intrinsic strength of the material. This limitation is particularly a problem in actuators using large-area films. Our recent studies have shown that the gap between the strength of the intrinsic material and the strength of large-area actuators can be reduced by electrically isolating defects in the dielectric film. As a result, the performance and reliability of dielectric elastomers actuators can be substantially improved.

  1. Electrodynamic actuators for rocket engine valves

    NASA Technical Reports Server (NTRS)

    Fiet, O.; Doshi, D.

    1972-01-01

    Actuators, employed in acoustic loudspeakers, operate liquid rocket engine valves by replacing light paper cones with flexible metal diaphragms. Comparative analysis indicates better response time than solenoid actuators, and improved service life and reliability.

  2. Self-encapsulation, or the ‘dripping’ of an elastic rod

    PubMed Central

    Bosi, F.; Misseroni, D.; Dal Corso, F.; Bigoni, D.

    2015-01-01

    A rod covering a fixed span is loaded at the middle with a transverse force, such that with increasing load a progressive deflection occurs. After a certain initial deflection, a phenomenon is observed where two points of the rod come in contact with each other. This is defined as the ‘dripping point’ and is when ‘self-encapsulation’ of the elastic rod occurs. Dripping seems at a first glance to be impossible and definitely cannot occur in the presence of ‘ordinary’ constraints (such as simple supports or clamps) at the ends of the span. However, the elastica governs oscillating pendulums, buckling rods and pendant drops, so that a possibility for self-encapsulation might be imagined. This phenomenon is indeed demonstrated (both theoretically and experimentally) to occur when at least one of the constraints at the ends of the rod is a sliding sleeve. This mechanical device generates a configurational force, causing the dripping of the rod, in a fully elastic set-up. PMID:26346447

  3. Distributed structural control using multilayered piezoelectric actuators

    NASA Technical Reports Server (NTRS)

    Cudney, Harley H.; Inman, Daniel J.; Oshman, Yaakov

    1990-01-01

    A method of segmenting piezoelectric sensors and actuators is proposed which can preclude the currently experienced cancelation of sensor signals, or the reduction of actuator effectiveness, due to the integration of the property undergoing measurement or control. The segmentation method is demonstrated by a model developed for beam structures, to which multiple layers of piezoelectric materials are attached. A numerical study is undertaken of increasing active and passive damping of a beam using the segmented sensors and actuators over unsegmented sensors and actuators.

  4. Piezoelectric Actuators On A Cold Finger

    NASA Technical Reports Server (NTRS)

    Kuo, Chin-Po; Garba, John A.; Glaser, Robert J.

    1995-01-01

    Developmental system for active suppression of vibrations of cold finger includes three piezoelectric actuators bonded to outer surface. Actuators used to suppress longitudinal and lateral vibrations of upper end of cold finger by applying opposing vibrations. Cold finger in question is part of a cryogenic system associated with an infrared imaging detector. When fully developed, system would be feedback sensor/control/actuator system automatically adapting to changing vibrational environment and suppresses pressure-induced vibrations by imposing compensatory vibrations via actuators.

  5. 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.

  6. Inflated Soft Actuators with Reversible Stable Deformations.

    PubMed

    Hines, Lindsey; Petersen, Kirstin; Sitti, Metin

    2016-05-01

    Most soft robotic systems are currently dependent on bulky compressors or pumps. A soft actuation method is presented combining hyperelastic membranes and dielectric elastomer actuators to switch between stable deformations of sealed chambers. This method is capable of large repeatable deformations, and has a number of stable states proportional to the number of actuatable membranes in the chamber. PMID:27008455

  7. Carbon nanotube-polymer composite actuators

    DOEpatents

    Gennett, Thomas; Raffaelle, Ryne P.; Landi, Brian J.; Heben, Michael J.

    2008-04-22

    The present invention discloses a carbon nanotube (SWNT)-polymer composite actuator and method to make such actuator. A series of uniform composites was prepared by dispersing purified single wall nanotubes with varying weight percents into a polymer matrix, followed by solution casting. The resulting nanotube-polymer composite was then successfully used to form a nanotube polymer actuator.

  8. Shape memory actuated release devices

    NASA Astrophysics Data System (ADS)

    Carpenter, Bernie F.; Clark, Cary R.; Weems, Weyman

    1996-05-01

    Spacecraft require a variety of separation and release devices to accomplish mission related functions. Current off-the-shelf devices such as pyrotechnics, gas-discharge systems, paraffin wax actuators, and other electro-mechanical devices may not be able to meet future design needs. The use of pyrotechnics on advanced lightweight spacecraft, for example, will expose fragile sensors and electronics to high shock levels and sensitive optics might be subject to contamination. Other areas of consideration include reliability, safety, and cost reduction. Shape memory alloys (SMA) are one class of actuator material that provides a solution to these design problems. SMA's utilize a thermally activated reversible phase transformation to recover their original heat treated shape (up to 8% strain) or to generate high recovery stresses (> 700 Mpa) when heated above a critical transition temperature. NiTiCu alloy actuators have been fabricated to provide synchronized, shockless separation within release mechanisms. In addition, a shape memory damper has been incorporated to absorb the elastic energy of the preload bolt and to electrically reset the device during ground testing. Direct resistive heating of the SMA actuators was accomplished using a programmable electric control system. Release times less than 40 msec have been determined using 90 watt-sec of power. Accelerometer data indicate less than 500 g's of shock were generated using a bolt preload of 1350 kgs.

  9. Electro-active paper actuators

    NASA Astrophysics Data System (ADS)

    Kim, Jaehwan; Seo, Yung B.

    2002-06-01

    In this paper, the actuation mechanism of electro-active paper (EAPap) actuators is addressed and the potential of the actuators is demonstrated. EAPap is a paper that produces large displacement with small force under an electrical excitation. EAPap is made with a chemically treated paper by constructing thin electrodes on both sides of the paper. When electrical voltage is applied on the electrodes the EAPap produces bending displacement. However, the displacement output has been unstable and degraded with timescale. To improve the bending performance of EAPap, different paper fibers - softwood, hardwood, bacteria cellulose, cellophane, carbon mixture paper, electrolyte containing paper and Korean traditional paper, in conjunction with additive chemicals, were tested. Two attempts were made to construct the electrodes: the direct use of aluminum foil and the gold sputtering technique. It was found that a cellophane paper exhibits a remarkable bending performance. When 2 MV m-1 excitation voltage was applied to the paper actuator, more than 3 mm tip displacement was observed from the 30 mm long paper beam. This is quite a low excitation voltage compared with that of other EAPs. Details of the experiments and results are addressed.

  10. Multilayer Piezoelectric Stack Actuator Characterization

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Jones, Christopher M.; Aldrich, Jack B.; Blodget, Chad; Bao, Xioaqi; Badescu, Mircea; Bar-Cohen, Yoseph

    2008-01-01

    Future NASA missions are increasingly seeking to use actuators for precision positioning to accuracies of the order of fractions of a nanometer. For this purpose, multilayer piezoelectric stacks are being considered as actuators for driving these precision mechanisms. In this study, sets of commercial PZT stacks were tested in various AC and DC conditions at both nominal and extreme temperatures and voltages. AC signal testing included impedance, capacitance and dielectric loss factor of each actuator as a function of the small-signal driving sinusoidal frequency, and the ambient temperature. DC signal testing includes leakage current and displacement as a function of the applied DC voltage. The applied DC voltage was increased to over eight times the manufacturers' specifications to investigate the correlation between leakage current and breakdown voltage. Resonance characterization as a function of temperature was done over a temperature range of -180C to +200C which generally exceeded the manufacturers' specifications. In order to study the lifetime performance of these stacks, five actuators from one manufacturer were driven by a 60volt, 2 kHz sine-wave for ten billion cycles. The tests were performed using a Lab-View controlled automated data acquisition system that monitored the waveform of the stack electrical current and voltage. The measurements included the displacement, impedance, capacitance and leakage current and the analysis of the experimental results will be presented.

  11. Status of Electrical Actuator Applications

    NASA Technical Reports Server (NTRS)

    Roth, Mary Ellen; Taylor, Linda M.; Hansen, Irving G.

    1996-01-01

    An ever increasing number of actuation functions historically performed by hydraulics or pneumatics are being accomplished by electric actuation. If 'end to end' systems are considered, electric actuators (EA's) are potentially lighter and more efficient. In general, system redundancies may be more easily implemented and operationally monitored. Typically, electrical components exhibit longer mean times to failure and projected lifetime costs of EA's are potentially much lower than those of other options. EA's have certain characteristics which must be considered in their application. The actual mechanical loadings must be established, for the more easily controlled EA may be operated much closer to its full capabilities. At higher rates of motion, EA's are operating as constant power devices. Therefore, it may be possible to start a movement that can not be stopped. The incorporation of high power electronics into remote locations introduces new concerns of EMI and thermal control. It is the management of these and other characteristics that forms the engineering design challenges. Work is currently in progress on EA's for aircraft and expendable launch vehicles. These applications span from ten to 40+ horsepower. The systematics and status of these actuators will be reported along with current technical trends in this area.

  12. Smart patch piezoceramic actuator issues

    NASA Technical Reports Server (NTRS)

    Griffin, Steven F.; Denoyer, Keith K.; Yost, Brad

    1993-01-01

    The Phillips Laboratory is undertaking the challenge of finding new and innovative ways to integrate sensing, actuation, and the supporting control and power electronics into a compact self-contained unit to provide vibration suppression for a host structure. This self-contained unit is commonly referred to as a smart patch. The interfaces to the smart patch will be limited to standard spacecraft power and possibly a communications line. The effort to develop a smart patch involves both contractual and inhouse programs which are currently focused on miniaturization of the electronics associated with vibrational control using piezoceramic sensors and actuators. This paper is comprised of two distinct parts. The first part examines issues associated with bonding piezoceramic actuators to a host structure. Experimental data from several specimens with varying flexural stiffness are compared to predictions from two piezoelectric/substructure coupling models, the Blocked Force Model and the Uniform Strain Model with Perfect Bonding. The second part of the paper highlights a demonstration article smart patch created using the insights gained from inhouse efforts at the Phillips Laboratory. This demonstration article has self contained electronics on the same order of size as the actuator powered by a voltage differential of approximately 32 volts. This voltage is provided by four rechargeable 8 volt batteries.

  13. Ball Aerospace Actuator Cryogenic Testing

    NASA Technical Reports Server (NTRS)

    Kingsbury, Lana; Lightsey, Paul; Quigley, Phil; Rutkowski, Joel; Russell, J. Kevin (Technical Monitor)

    2002-01-01

    The ambient testing characterizing step size and repeatability for the Ball Aerospace Cryogenic Nano-Positioner actuators for the AMSD (Advanced Mirror System Demonstrator) program has been completed and are presented. Current cryogenic testing is underway. Earlier cryogenic test results for a pre-cursor engineering model are presented.

  14. Smart patch piezoceramic actuator issues

    NASA Astrophysics Data System (ADS)

    Griffin, Steven F.; Denoyer, Keith K.; Yost, Brad

    1993-02-01

    The Phillips Laboratory is undertaking the challenge of finding new and innovative ways to integrate sensing, actuation, and the supporting control and power electronics into a compact self-contained unit to provide vibration suppression for a host structure. This self-contained unit is commonly referred to as a smart patch. The interfaces to the smart patch will be limited to standard spacecraft power and possibly a communications line. The effort to develop a smart patch involves both contractual and inhouse programs which are currently focused on miniaturization of the electronics associated with vibrational control using piezoceramic sensors and actuators. This paper is comprised of two distinct parts. The first part examines issues associated with bonding piezoceramic actuators to a host structure. Experimental data from several specimens with varying flexural stiffness are compared to predictions from two piezoelectric/substructure coupling models, the Blocked Force Model and the Uniform Strain Model with Perfect Bonding. The second part of the paper highlights a demonstration article smart patch created using the insights gained from inhouse efforts at the Phillips Laboratory. This demonstration article has self contained electronics on the same order of size as the actuator powered by a voltage differential of approximately 32 volts. This voltage is provided by four rechargeable 8 volt batteries.

  15. Piezoelectric multilayer actuator life test.

    PubMed

    Sherrit, Stewart; Bao, Xiaoqi; Jones, Christopher M; Aldrich, Jack B; Blodget, Chad J; Moore, James D; Carson, John W; Goullioud, Renaud

    2011-04-01

    Potential NASA optical missions such as the Space Interferometer Mission require actuators for precision positioning to accuracies of the order of nanometers. Commercially available multilayer piezoelectric stack actuators are being considered for driving these precision mirror positioning mechanisms. These mechanisms have potential mission operational requirements that exceed 5 years for one mission life. To test the feasibility of using these commercial actuators for these applications and to determine their reliability and the redundancy requirements, a life test study was undertaken. The nominal actuator requirements for the most critical actuators on the Space Interferometry Mission (SIM) in terms of number of cycles was estimated from the Modulation Optics Mechanism (MOM) and Pathlength control Optics Mechanism (POM) and these requirements were used to define the study. At a nominal drive frequency of 250 Hz, one mission life is calculated to be 40 billion cycles. In this study, a set of commercial PZT stacks configured in a potential flight actuator configuration (pre-stressed to 18 MPa and bonded in flexures) were tested for up to 100 billion cycles. Each test flexure allowed for two sets of primary and redundant stacks to be mechanically connected in series. The tests were controlled using an automated software control and data acquisition system that set up the test parameters and monitored the waveform of the stack electrical current and voltage. The samples were driven between 0 and 20 V at 2000 Hz to accelerate the life test and mimic the voltage amplitude that is expected to be applied to the stacks during operation. During the life test, 10 primary stacks were driven and 10 redundant stacks, mechanically in series with the driven stacks, were open-circuited. The stroke determined from a strain gauge, the temperature and humidity in the chamber, and the temperature of each individual stack were recorded. Other properties of the stacks, including the

  16. Flexible Low-Mass Devices and Mechanisms Actuated by Electroactive Polymers

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Y; Leary, S.; Shahinpoor, M.; Harrison, J. O.; Smith, J.

    1999-01-01

    Miniature, lightweight, miser actuators that operate similar to biological muscles can be used to develop robotic devices with unmatched capabilities to impact many technology areas. Electroactive polymers (EAP) offer the potential to producing such actuators and their main attractive feature is their ability to induce relatively large bending or longitudinal strain. Generally, these materials produce a relatively low force and the applications that can be considered at the current state of the art are relatively limited. This reported study is concentrating on the development of effective EAPs and the resultant enabling mechanisms employing their unique characteristics. Several EAP driven mechanisms, which emulate human hand, were developed including a gripper, manipulator arm and surface wiper. The manipulator arm was made of a composite rod with an EAP actuator consisting of a scrolled rope that is activated longitudinally by an electrostatic field. A gripper was made to serve as an end effector and it consisted of multiple bending EAP fingers for grabbing and holding such objects as rocks. An EAP surface wiper was developed to operate like a human finger and to demonstrate the potential to remove dust from optical and IR windows as well as solar cells. These EAP driven devices are taking advantage of the large actuation displacement of these materials but there is need for a significantly greater actuation force capability.

  17. Stuck fuel rod capping sleeve

    DOEpatents

    Gorscak, Donald A.; Maringo, John J.; Nilsen, Roy J.

    1988-01-01

    A stuck fuel rod capping sleeve to be used during derodding of spent fuel assemblies if a fuel rod becomes stuck in a partially withdrawn position and, thus, has to be severed. The capping sleeve has an inner sleeve made of a lower work hardening highly ductile material (e.g., Inconel 600) and an outer sleeve made of a moderately ductile material (e.g., 304 stainless steel). The inner sleeve may be made of an epoxy filler. The capping sleeve is placed on a fuel rod which is then severed by using a bolt cutter device. Upon cutting, the capping sleeve deforms in such a manner as to prevent the gross release of radioactive fuel material

  18. Advanced gray rod control assembly

    DOEpatents

    Drudy, Keith J; Carlson, William R; Conner, Michael E; Goldenfield, Mark; Hone, Michael J; Long, Jr., Carroll J; Parkinson, Jerod; Pomirleanu, Radu O

    2013-09-17

    An advanced gray rod control assembly (GRCA) for a nuclear reactor. The GRCA provides controlled insertion of gray rod assemblies into the reactor, thereby controlling the rate of power produced by the reactor and providing reactivity control at full power. Each gray rod assembly includes an elongated tubular member, a primary neutron-absorber disposed within the tubular member said neutron-absorber comprising an absorber material, preferably tungsten, having a 2200 m/s neutron absorption microscopic capture cross-section of from 10 to 30 barns. An internal support tube can be positioned between the primary absorber and the tubular member as a secondary absorber to enhance neutron absorption, absorber depletion, assembly weight, and assembly heat transfer characteristics.

  19. Development of shape memory alloy (SMA) torsional actuators for variable twist tilt rotor (VTTR) blades

    NASA Astrophysics Data System (ADS)

    Prahlad, Harsha

    This dissertation presents the development of a torsional actuator to alter the twist distributions of a tiltrotor blade between hover and forward flight. The actuator uses a Shape Memory Alloy (SMA) tube as its active element. The historical development of the tiltrotor aircraft is discussed, with emphasis on advanced tiltrotor concepts. The central theme in these concepts is to reduce the compromises for tiltrotor blade design, thereby improving performance of the aircraft in both hover and forward flight modes. A survey of research conducted in the application of smart structures to performance enhancement of aircraft is conducted. A review of other torsional actuators that are based on SMAs is presented. An assessment of the state-of-the-art in SMA modeling and characterization, both in mechanical tensile and torsional loading, is also discussed. Shape Memory Alloys are "smart" actuation materials that are capable of providing high stroke and high force of actuation at relatively low bandwidth. However, their behavior is complex, and influenced by material non-linearities, thermo-mechanical conditions and history of loading. In addition, the behavior of torsional SMA actuators has not been investigated in detail. In order to address these issues, the current research carries out a comprehensive characterization of SMAs. Experimental characteristics of SMA wires under extensional loading, and SMA rods and tubes in both extensional and torsional loading under a variety of thermo-mechanical conditions are presented in this dissertation. It is demonstrated that the uniaxial quasistatic SMA models show good overall agreement with the experimental behavior of an SMA wire under extensional loading. In addition, an approach that incorporates these models with radial non-uniformity due to torsional deflections is shown to provide good predictions of torsional characteristics of SMA rods and tubes. Several differences of the material response under non

  20. Composite flight-control actuator development

    NASA Technical Reports Server (NTRS)

    Bott, Richard; Ching, Fred

    1992-01-01

    The composite actuator is 'jam resistant', satisfying a survivability requirement for the Navy. Typically, the push-pull force needed to drive through the wound area of the composite actuator is 73 percent less than that of an all-metal actuator. In addition to improving the aircraft's combat survivability, significant weight savings were realized. The current design of the survivable, composite actuator cylinder is 36 percent lighter than that of the production steel cylinder, which equates to a 15 percent overall actuator weight savings.

  1. Dual load path ball screw with rod end swivel

    NASA Technical Reports Server (NTRS)

    Wngett, Paul (Inventor)

    2002-01-01

    A dual drive ball has a ball screw shaft coupled at one end to a gear train and coupled at the other end to a ball screw nut. The ball screw shaft and ball screw nut are connected through complementary helical grooves filled with ball bearing balls. The outer surface of the ball screw nut is plined and can be driven by a second gear train. An output tube is coupled at one end to the ball screw nut and at its opposite end has a connector portion with a groove on its inner surface. A rod end has a coupling member for coupling to a surface to be actuated and a shaft portion with a groobe on its outer surface. This shaft portion is received with in the outputtube portion and the corresponding grooves are coupled through the use of a plurality of ball bearing balls.

  2. Mars Science Laboratory Rover Actuator Thermal Design

    NASA Technical Reports Server (NTRS)

    Novak, Keith S.; Liu, Yuanming; Lee, Chern-Jiin; Hendricks, Steven

    2010-01-01

    NASA will launch a 900 kg rover, part of the Mars Science Laboratory (MSL) mission, to Mars in October of 2011. The MSL rover is scheduled to land on Mars in August of 2012. The rover employs 31, electric-motor driven actuators to perform a variety of engineering and science functions including: mobility, camera pointing, telecommunications antenna steering, soil and rock sample acquisition and sample processing. This paper describes the MSL rover actuator thermal design. The actuators have stainless steel housings and planetary gearboxes that are lubricated with a "wet" lubricant. The lubricant viscosity increases with decreasing temperature. Warm-up heaters are required to bring the actuators up to temperature (above -55 C) prior to use in the cold wintertime environment of Mars (when ambient atmosphere temperatures are as cold as -113 C). Analytical thermal models of all 31 MSL actuators have been developed. The actuators have been analyzed and warm-up heaters have been designed to improve actuator performance in cold environments. Thermal hardware for the actuators has been specified, procured and installed. This paper presents actuator thermal analysis predicts, and describes the actuator thermal hardware and its operation. In addition, warm-up heater testing and thermal model correlation efforts for the Remote Sensing Mast (RSM) elevation actuator are discussed.

  3. Development of micro inchworm robot actuated by electrostrictive polymer actuator

    NASA Astrophysics Data System (ADS)

    Cho, Sunghwi; Ryew, Sungmoo; Jeon, Jaewook; Kim, Hunmo; Nam, Jaedo; Choi, Hyoukryeol

    2001-07-01

    In previous works, the possibility of the electrostrictive polymer as the actuator use has been proved. In this paper we address an actual design of an actuator and an inchworm type robotic mechanism using the electrostrictive polymer. The robot will be developed to move horizontally, vertically with steering capability, aiming for navigation in small tubular structures such as flexible pipes but now in this stage a simple bellows type robot capable of accomplishing the linear movement like that of an inchworm is introduced. The issues about the mechanism design of the prototype, which has already been developed and under the consideration of reduction in size, are discussed and preliminary results of experiments are given.

  4. Novel applications of plasma actuators

    NASA Astrophysics Data System (ADS)

    Ozturk, Arzu Ceren

    The current study investigates the effectiveness of two different dielectric barrier discharge plasma actuator configurations, a 3-D annular geometry for use in micro thrusters and internal duct aerodynamics and a jet vectoring actuator that acts as a vortex generator and flow control device. The first configuration consists of a closed circumferential arrangement which yields a body force when a voltage difference is applied across the inner and outer electrodes separated by a dielectric. The primary flow is driven by this zero-net mass flux jet at the wall that then entrains fluid in the core of the duct. PIV experiments in both quiescent flow and freestream are conducted on tubes of different diameters while varying parameters such as the modulation frequency, duty cycle and tunnel speed. The values of the induced velocities increase with the forcing frequency and duty cycle although there is a peak value for the forcing frequency after which the velocity and thrust decrease for each thruster. The velocities and thrust increase as the inner diameter of the tubes are increased while the velocity profiles show a great difference with the (l/di) ratio; recirculation occurs after going below a critical value. Experiments in the wind tunnel illustrate that the jet exit characteristics significantly change upon actuation in freestream flow but the effect tends to diminish with increasing inner diameters and tunnel speeds. Using staged arrays of these thrusters result in higher velocities while operating at both in phase and out of phase. The jet vectoring configuration consists of a single embedded electrode separated from two exposed electrodes on either side by the dielectric. The embedded electrode is grounded while the exposed electrodes are driven with a high frequency high voltage input signal. PIV measurements of the actuator in a freestream show that vectoring the jet yields stronger vortices than a linear configuration and increasing the difference between

  5. Efficient Hybrid Actuation Using Solid-State Actuators

    NASA Technical Reports Server (NTRS)

    Leo, Donald J.; Cudney, Harley H.; Horner, Garnett (Technical Monitor)

    2001-01-01

    Piezohydraulic actuation is the use of fluid to rectify the motion of a piezoelectric actuator for the purpose of overcoming the small stroke limitations of the material. In this work we study a closed piezohydraulic circuit that utilizes active valves to rectify the motion of a hydraulic end affector. A linear, lumped parameter model of the system is developed and correlated with experiments. Results demonstrate that the model accurately predicts the filtering of the piezoelectric motion caused by hydraulic compliance. Accurate results are also obtained for predicting the unidirectional motion of the cylinder when the active valves are phased with respect to the piezoelectric actuator. A time delay associated with the mechanical response of the valves is incorporated into the model to reflect the finite time required to open or close the valves. This time delay is found to be the primary limiting factor in achieving higher speed and greater power from the piezohydraulic unit. Experiments on the piezohydraulic unit demonstrate that blocked forces on the order of 100 N and unloaded velocities of 180 micrometers/sec are achieved.

  6. Light-Driven Polymeric Bimorph Actuators

    NASA Technical Reports Server (NTRS)

    Adamovsky, Gregory; Sarkisov, Sergey S.; Curley, Michael J.

    2009-01-01

    Light-driven polymeric bimorph actuators are being developed as alternatives to prior electrically and optically driven actuators in advanced, highly miniaturized devices and systems exemplified by microelectromechanical systems (MEMS), micro-electro-optical-mechanical systems (MEOMS), and sensor and actuator arrays in smart structures. These light-driven polymeric bimorph actuators are intended to satisfy a need for actuators that (1) in comparison with the prior actuators, are simpler and less power-hungry; (2) can be driven by low-power visible or mid-infrared light delivered through conventional optic fibers; and (3) are suitable for integration with optical sensors and multiple actuators of the same or different type. The immediate predecessors of the present light-driven polymeric bimorph actuators are bimorph actuators that exploit a photorestrictive effect in lead lanthanum zirconate titanate (PLZT) ceramics. The disadvantages of the PLZT-based actuators are that (1) it is difficult to shape the PLZT ceramics, which are hard and brittle; (2) for actuation, it is necessary to use ultraviolet light (wavelengths < 380 nm), which must be generated by use of high-power, high-pressure arc lamps or lasers; (3) it is difficult to deliver sufficient ultraviolet light through conventional optical fibers because of significant losses in the fibers; (4) the response times of the PLZT actuators are of the order of several seconds unacceptably long for typical applications; and (5) the maximum mechanical displacements of the PLZT-based actuators are limited to those characterized by low strains beyond which PLZT ceramics disintegrate because of their brittleness. The basic element of a light-driven bimorph actuator of the present developmental type is a cantilever beam comprising two layers, at least one of which is a polymer that exhibits a photomechanical effect (see figure). The dominant mechanism of the photomechanical effect is a photothermal one: absorption of

  7. The sliding mode control for different shapes and dimensions of IPMC on resisting its creep characteristics

    NASA Astrophysics Data System (ADS)

    Hao, Lina; Chen, Yang; Sun, Zhiyong

    2015-04-01

    Ionic polymer metal composite (IPMC) is a novel smart material which has been widely implemented in MEMS, biomimetic mechanical and electrical integrated system and micro operation system. While the IPMC with different shapes and dimensions has been implemented in many different types of biomechanical integrated systems, one of its inherent properties called creep characteristic is difficult to be handled, which limits the further application of different IPMCs in integrated systems. A promising control method called sliding mode control (SMC) is proposed to resist the creep characteristics in this paper. The SMC controller can regulate IPMC actuators with different shapes and dimensions effectively to resist the creep characteristics without changing parameters of the control system. Experiments of four different types of IPMC actuators were conducted on the semi-physical SMC experimental platform. All the experimental results confirm the feasibility of the SMC control approach on regulating the multi-IPMCs with different shapes and dimensions based integrated system.

  8. Pleistocene Suvero slide, Paola basin, southern Italy

    USGS Publications Warehouse

    Trincardi, F.; Normark, W.R.

    1989-01-01

    The Suvero slide covers an area of about 225 km2 in the Paola slope basin on the Eastern Tyrrhenian margin. The shape and lateral extent of the deposit reflect topographic confinement of the slide between the continental slope and a morphologic barrier formed by a margin-parallel slope ridge. No headwall or slide plane comparable in scale with the slide deposit were found, suggesting that quasi in situ deformation of semi-consolidated sediments took place when the failed materials reached the floor of the slope basin. The failure occurred downslope from a basement high originating from local uplift. Continued uplift, after the Suvero slide occurred, is documented by the presence of steep upper-slope gradients within the study area and by the presence of small-scale creep and failure events that postdate the Suvero slide. ?? 1989.

  9. 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.

  10. Turbulent Motion of Liquids in Hydraulic Resistances with a Linear Cylindrical Slide-Valve

    PubMed Central

    Velescu, C.; Popa, N. C.

    2015-01-01

    We analyze the motion of viscous and incompressible liquids in the annular space of controllable hydraulic resistances with a cylindrical linear slide-valve. This theoretical study focuses on the turbulent and steady-state motion regimes. The hydraulic resistances mentioned above are the most frequent type of hydraulic resistances used in hydraulic actuators and automation systems. To study the liquids' motion in the controllable hydraulic resistances with a linear cylindrical slide-valve, the report proposes an original analytic method. This study can similarly be applied to any other type of hydraulic resistance. Another purpose of this study is to determine certain mathematical relationships useful to approach the theoretical functionality of hydraulic resistances with magnetic controllable fluids as incompressible fluids in the presence of a controllable magnetic field. In this report, we established general analytic equations to calculate (i) velocity and pressure distributions, (ii) average velocity, (iii) volume flow rate of the liquid, (iv) pressures difference, and (v) radial clearance. PMID:26167532

  11. Three-Rod Linear Ion Traps

    NASA Technical Reports Server (NTRS)

    Janik, Gary R.; Prestage, John D.; Maleki, Lutfollah

    1993-01-01

    Three-parallel-rod electrode structures proposed for use in linear ion traps and possibly for electrostatic levitation of macroscopic particles. Provides wider viewing angle because they confine ions in regions outside rod-electrode structures.

  12. Control rods in LMFBRs: a physics assessment

    SciTech Connect

    McFarlane, H.F.; Collins, P.J.

    1982-08-01

    This physics assessment is based on roughly 300 control rod worth measurements in ZPPR from 1972 to 1981. All ZPPR assemblies simulated mixed-oxide LMFBRs, representing sizes of 350, 700, and 900 MWe. Control rod worth measurements included single rods, various combinations of rods, and Ta and Eu rods. Additional measurements studied variations in B/sub 4/C enrichment, rod interaction effects, variations in rod geometry, neutron streaming in sodium-filled channels, and axial worth profiles. Analyses were done with design-equivalent methods, using ENDF/B Version IV data. Some computations for the sensitivities to approximations in the methods have been included. Comparisons of these analyses with the experiments have allowed the status of control rod physics in the US to be clearly defined.

  13. Development of High Efficiency Ventilation Bag Actuated Dry Powder Inhalers

    PubMed Central

    Behara, Srinivas R.B.; Longest, P. Worth; Farkas, Dale R.; Hindle, Michael

    2014-01-01

    New active dry powder inhaler systems were developed and tested to efficiently aerosolize a carrier-free formulation. To assess inhaler performance, a challenging case study of aerosol lung delivery during high-flow nasal cannula (HFNC) therapy was selected. The active delivery system consisted of a ventilation bag for actuating the device, the DPI containing a flow control orifice and 3D rod array, and streamlined nasal cannula with separate inlets for the aerosol and HFNC therapy gas. In vitro experiments were conducted to assess deposition in the device, emitted dose (ED) from the nasal cannula, and powder deaggregation. The best performing systems achieved EDs of 70–80% with fine particle fractions <5 μm of 65–85% and mass median aerodynamic diameters of 1.5 μm, which were target conditions for controlled condensational growth aerosol delivery. Decreasing the size of the flow control orifice from 3.6 to 2.3 mm reduced the flow rate through the system with manual bag actuations from an average of 35 to 15 LPM, while improving ED and aerosolization performance. The new devices can be applied to improve aerosol delivery during mechanical ventilation, nose-to-lung aerosol administration, and to assist patients that cannot reproducibly use passive DPIs. PMID:24508552

  14. Sliding Mode Control Technique: Application to a Four Rotors Mini-Flying Robot

    NASA Astrophysics Data System (ADS)

    Zemalache, K. M.; Tahar, M.; Omari, A.; Maaref, H.

    2009-03-01

    This paper presents the study of stabilization with motion planning of the four rotors mini-flying robot (helicopter with four rotors). The dynamic model involves four control inputs which are computed to stabilize the engine with predefined trajectories path. The tracking feedback controller is based on receding horizon point to point steering. It is clear that our device belongs to families of under-actuated systems. Our aim is to obtain control algorithms using the cascade sliding mode approach in order to stabilize the engine and to generate its trajectory.

  15. Piezoelectric aluminum nitride nanoelectromechanical actuators

    NASA Astrophysics Data System (ADS)

    Sinha, Nipun; Wabiszewski, Graham E.; Mahameed, Rashed; Felmetsger, Valery V.; Tanner, Shawn M.; Carpick, Robert W.; Piazza, Gianluca

    2009-08-01

    This letter reports the implementation of ultrathin (100 nm) aluminum nitride (AlN) piezoelectric layers for the fabrication of vertically deflecting nanoactuators. The films exhibit an average piezoelectric coefficient (d31˜-1.9 pC/N), which is comparable to its microscale counterpart. This allows vertical deflections as large as 40 nm from 18 μm long and 350 nm thick multilayer cantilever bimorph beams with 2 V actuation. Furthermore, in-plane stress and stress gradients have been simultaneously controlled. The films exhibit leakage currents lower than 2 nA/cm2 at 1 V, and have an average relative dielectric constant of approximately 9.2 (as in thicker films). These material characteristics and actuation results make the AlN nanofilms ideal candidates for the realization of nanoelectromechanical switches for low power logic applications.

  16. Hydraulically amplified PZT mems actuator

    DOEpatents

    Miles, Robin R.

    2004-11-02

    A hydraulically amplified microelectromechanical systems actuator. A piece of piezoelectric material or stacked piezo bimorph is bonded or deposited as a thin film. The piece is operatively connected to a primary membrane. A reservoir is operatively connected to the primary membrane. The reservoir contains a fluid. A membrane is operatively connected to the reservoir. In operation, energizing the piezoelectric material causing the piezoelectric material to bow. Bowing of the piezoelectric material causes movement of the primary membrane. Movement of the primary membrane results in a force in being transmitted to the liquid in the reservoir. The force in the liquid causes movement of the membrane. Movement of the membrane results in an operating actuator.

  17. Impact micro-positioning actuator

    NASA Technical Reports Server (NTRS)

    Cuerden, Brian (Inventor); Angel, J. Roger P. (Inventor); Burge, James H. (Inventor); DeRigne, Scott T. (Inventor)

    2006-01-01

    An impact micro-positioning actuator. In one aspect of the invention, a threaded shaft is threadably received in a nut and the nut is impacted by an impacting device, causing the nut first to rotate relative to the shaft by slipping as a result of shaft inertia and subsequently to stick to the shaft as a result of the frictional force therebetween. The nut is returned to its initial position by a return force provided by a return mechanism after impact. The micro-positioning actuator is further improved by controlling at least one and preferably all of the following: the friction, the impact provided by the impacting device, the return force provided by the return mechanism, and the inertia of the shaft. In another aspect of the invention, a threaded shaft is threadably received in a nut and the shaft is impacted by an impacting device, causing the shaft to rotate relative to the nut.

  18. Secondary Reverse Slide Tracheoplasty for Airway Rescue.

    PubMed

    Kopelovich, Jonathan C; Wine, Todd M; Rutter, Michael J; Mitchell, Max B; Prager, Jeremy D

    2016-03-01

    Slide tracheoplasty is used in cases of tracheal stenosis or injury. With expanding indications for its use at tertiary centers, salvage techniques for dehiscence or restenosis after slide tracheoplasty are increasingly relevant. We present a case in which slide tracheoplasty was augmented with an anterior costochondral graft that stenosed again and ultimately failed. We salvaged this airway emergency by performing a secondary reverse slide tracheoplasty. Using this technique, we were able to establish a safe and durable airway using only native airway tissue. PMID:26897214

  19. 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)

  20. "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

  1. Solid-state-laser-rod holder

    DOEpatents

    Gettemy, D.J.; Barnes, N.P.; Griggs, J.E.

    1981-08-11

    The disclosure relates to a solid state laser rod holder comprising Invar, copper tubing, and epoxy joints. Materials and coefficients of expansion of the components of the holder combine with the rod to produce a joint which will give before the rod itself will. The rod may be lased at about 70 to 80/sup 0/K and returned from such a temperature to room temperature repeatedly without its or the holder's destruction.

  2. Actuator device for artificial leg

    NASA Technical Reports Server (NTRS)

    Burch, J. L. (Inventor)

    1976-01-01

    An actuator device is described for moving an artificial leg of a person having a prosthesis replacing an entire leg and hip joint. The device includes a first articulated hip joint assembly carried by the natural leg and a second articulated hip joint assembly carried by the prosthesis whereby energy from the movement of the natural leg is transferred by a compressible fluid from the first hip joint assembly to the second hip joint assembly for moving the artificial leg.

  3. Enhancing the force capability of permanent magnet latching actuators for electromechanical valve actuation systems

    NASA Astrophysics Data System (ADS)

    Rens, J.; Clark, R. E.; Jewell, G. W.; Howe, D.

    2005-05-01

    This article introduces a topology of parallel-polarized permanent magnet latching actuator for use in electromagnetic valve actuation systems for internal combustion engines. The actuator has a number of advantages over reluctance actuators, commonly employed in such systems, in terms of reduced starting currents and fail-safe capability. The influence of a number of design features on actuator performance, such as tooth tapering, additional magnets to improve the main magnet flux path and prevent the onset of saturation, and mechanical clearances required to protect the permanent magnet from shock loads are investigated. The design study findings are verified by measurements on a prototype actuator.

  4. Actuators for a space manipulator

    NASA Technical Reports Server (NTRS)

    Chun, W.; Brunson, P.

    1987-01-01

    The robotic manipulator can be decomposed into distinct subsytems. One particular area of interest of mechanical subsystems is electromechanical actuators (or drives). A drive is defined as a motor with an appropriate transmission. An overview is given of existing, as well as state-of-the-art drive systems. The scope is limited to space applications. A design philosophy and adequate requirements are the initial steps in designing a space-qualified actuator. The focus is on the d-c motor in conjunction with several types of transmissions (harmonic, tendon, traction, and gear systems). The various transmissions will be evaluated and key performance parameters will be addressed in detail. Included in the assessment is a shuttle RMS joint and a MSFC drive of the Prototype Manipulator Arm. Compound joints are also investigated. Space imposes a set of requirements for designing a high-performance drive assembly. Its inaccessibility and cryogenic conditions warrant special considerations. Some guidelines concerning these conditions are present. The goal is to gain a better understanding in designing a space actuator.

  5. 21 CFR 876.4270 - Colostomy rod.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Colostomy rod. 876.4270 Section 876.4270 Food and... GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4270 Colostomy rod. (a) Identification. A colostomy rod is a device used during the loop colostomy procedure. A loop of colon is surgically brought out...

  6. 21 CFR 876.4270 - Colostomy rod.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Colostomy rod. 876.4270 Section 876.4270 Food and... GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4270 Colostomy rod. (a) Identification. A colostomy rod is a device used during the loop colostomy procedure. A loop of colon is surgically brought out...

  7. 21 CFR 876.4270 - Colostomy rod.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Colostomy rod. 876.4270 Section 876.4270 Food and... GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4270 Colostomy rod. (a) Identification. A colostomy rod is a device used during the loop colostomy procedure. A loop of colon is surgically brought out...

  8. 21 CFR 876.4270 - Colostomy rod.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Colostomy rod. 876.4270 Section 876.4270 Food and... GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4270 Colostomy rod. (a) Identification. A colostomy rod is a device used during the loop colostomy procedure. A loop of colon is surgically brought out...

  9. Inverted Control Rod Lock-In Device

    DOEpatents

    Brussalis, W. G.; Bost, G. E.

    1962-12-01

    A mechanism which prevents control rods from dropping out of the reactor core in the event the vessel in which the reactor is mounted should capsize is described. The mechanism includes a pivoted toothed armature which engages the threaded control rod lead screw and prevents removal of the rod whenever the armature is not attracted by the provided electromagnetic means. (AEC)

  10. 21 CFR 876.4270 - Colostomy rod.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Colostomy rod. 876.4270 Section 876.4270 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4270 Colostomy rod. (a) Identification. A colostomy rod...

  11. Fuel followed control rod installation at AFRRI

    SciTech Connect

    Moore, Mark; Owens, Chris; Forsbacka, Matt

    1992-07-01

    Fuel Followed Control Rods (FFCRs) were installed at the Armed Forces Radiobiology Research Institute's 1 MW TRIGA Reactor. The procedures for obtaining, shipping, and installing the FFCRs is described. As part of the FFCR installation, the transient rod drive was relocated. Core performance due to the addition of the fuel followed control rods is discussed. (author)

  12. Design of high performance piezo composites actuators

    NASA Astrophysics Data System (ADS)

    Almajid, Abdulhakim A.

    Design of high performance piezo composites actuators are developed. Functionally Graded Microstructure (FGM) piezoelectric actuators are designed to reduce the stress concentration at the middle interface existed in the standard bimorph actuators while maintaining high actuation performance. The FGM piezoelectric laminates are composite materials with electroelastic properties varied through the laminate thickness. The elastic behavior of piezo-laminates actuators is developed using a 2D-elasticity model and a modified classical lamination theory (CLT). The stresses and out-of-plane displacements are obtained for standard and FGM piezoelectric bimorph plates under cylindrical bending generated by an electric field throughout the thickness of the laminate. The analytical model is developed for two different actuator geometries, a rectangular plate actuator and a disk shape actuator. The limitations of CLT are investigated against the 2D-elasticity model for the rectangular plate geometry. The analytical models based on CLT (rectangular and circular) and 2D-elasticity are compared with a model based on Finite Element Method (FEM). The experimental study consists of two FGM actuator systems, the PZT/PZT FGM system and the porous FGM system. The electroelastic properties of each layer in the FGM systems were measured and input in the analytical models to predict the FGM actuator performance. The performance of the FGM actuator is optimized by manipulating the thickness of each layer in the FGM system. The thickness of each layer in the FGM system is made to vary in a linear or non-linear manner to achieve the best performance of the FGM piezoelectric actuator. The analytical and FEM results are found to agree well with the experimental measurements for both rectangular and disk actuators. CLT solutions are found to coincide well with the elasticity solutions for high aspect ratios while the CLT solutions gave poor results compared to the 2D elasticity solutions for

  13. Synaptic transmission from rods to rod-dominated bipolar cells in the tiger salamander retina.

    PubMed

    Yang, X L; Wu, S M

    1993-06-11

    Synaptic transmission between photoreceptors and bipolar cells was studied in dark-adapted tiger salamander retinas. Based on the relative light sensitivity, bipolar cells, either depolarizing (DBC) or hyperpolarizing (HBC), fell into two groups: one receives inputs primarily from rods (rod-dominated bipolar cells, DBCR and HBCR) and the other receives inputs primarily from cones (cone-dominated bipolar cells, DBCC and HBCC). The input-output relations of the rod-DBCR and rod-HBCR synapses were determined by plotting the voltage responses of the rod and DBCR (or HBCR) to dim 500-nm light steps, which polarizes only the rods but not the cones. The slope gains of both synapses were the highest near the dark rod voltage (-2.5 for the rod-DBCR synapse and 4.0 for the rod-HBCR synapse), and they (the absolute values) became progressively smaller at more hyperpolarized rod voltages. PMID:8186975

  14. ELECTROMAGNETIC APPARATUS FOR MOVING A ROD

    DOEpatents

    Young, J.N.

    1958-04-22

    An electromagnetic apparatus for moving a rod-like member in small steps in either direction is described. The invention has particular application in the reactor field where the reactor control rods must be moved only a small distance and where the use of mechanical couplings is impractical due to the high- pressure seals required. A neutron-absorbing rod is mounted in a housing with gripping uaits that engage the rod, and coils for magnetizing the gripping units to make them grip, shift, and release the rod are located outside the housing.

  15. Rod cluster having improved vane configuration

    SciTech Connect

    Shockling, L.A.; Francis, T.A.

    1989-09-05

    This patent describes a pressurized water reactor vessel, the vessel defining a predetermined axial direction of the flow of coolant therewithin and having plural spider assemblies supporting, for vertical movement within the vessel, respective clusters of rods in spaced, parallel axial relationship, parallel to the predetermined axial direction of coolant flow, and a rod guide for each spider assembly and respective cluster of rods. The rod guide having horizontally oriented support plates therewithin, each plate having an interior opening for accommodating axial movement therethrough of the spider assembly and respective cluster of rods. The opening defining plural radially extending channels and corresponding parallel interior wall surfaces of the support plate.

  16. Microwave Power for Smart Membrane Actuators

    NASA Technical Reports Server (NTRS)

    Choi, Sang H.; Song, Kyo D.; Golembiewski, Walter T.; Chu, Sang-Hyon; King, Glen C.

    2002-01-01

    The concept of microwave-driven smart membrane actuators is envisioned as the best option to alleviate the complexity associated with hard-wired control circuitry. A large, ultra-light space structure, such as solar sails and Gossamer spacecrafts, requires a distribution of power into individual membrane actuators to control them in an effective way. A patch rectenna array with a high voltage output was developed to drive smart membrane actuators. Networked patch rectenna array receives and converts microwave power into a DC power for an array of smart actuators. To use microwave power effectively, the concept of a power allocation and distribution (PAD) circuit is developed and tested for networking a rectenna/actuator patch array. For the future development, the PAD circuit could be imbedded into a single embodiment of rectenna and actuator array with the thin-film microcircuit embodiment. Preliminary design and fabrication of PAD circuitry that consists of a sixteen nodal elements were made for laboratory testing.

  17. Plasma actuators for bluff body flow control

    NASA Astrophysics Data System (ADS)

    Kozlov, Alexey V.

    The aerodynamic plasma actuators have shown to be efficient flow control devices in various applications. In this study the results of flow control experiments utilizing single dielectric barrier discharge plasma actuators to control flow separation and unsteady vortex shedding from a circular cylinder in cross-flow are reported. This work is motivated by the need to reduce landing gear noise for commercial transport aircraft via an effective streamlining created by the actuators. The experiments are performed at Re D = 20,000...164,000. Circular cylinders in cross-flow are chosen for study since they represent a generic flow geometry that is similar in all essential aspects to a landing gear oleo or strut. The minimization of the unsteady flow separation from the models and associated large-scale wake vorticity by using actuators reduces the radiated aerodynamic noise. Using either steady or unsteady actuation at ReD = 25,000, Karman shedding is totally eliminated, turbulence levels in the wake decrease significantly and near-field sound pressure levels are reduced by 13.3 dB. Unsteady actuation at an excitation frequency of St D = 1 is found to be most effective. The unsteady actuation also has the advantage that total suppression of shedding is achieved for a duty cycle of only 25%. However, since unsteady actuation is associated with an unsteady body force and produces a tone at the actuation frequency, steady actuation is more suitable for noise control applications. Two actuation strategies are used at ReD = 82,000: spanwise and streamwise oriented actuators. Near field microphone measurements in an anechoic wind tunnel and detailed study of the near wake using LDA are presented in the study. Both spanwise and streamwise actuators give nearly the same noise reduction level of 11.2 dB and 14.2 dB, respectively, and similar changes in the wake velocity profiles. The contribution of the actuator induced noise is found to be small compared to the natural shedding

  18. Silkworm protein: its possibility as an actuator

    NASA Astrophysics Data System (ADS)

    Jin, Hyoung-Joon; Myung, Seung Jun; Kim, Heung Soo; Jung, Woochul; Kim, Jaehwan

    2006-03-01

    The possibility of silkworm (Bombyx mori) protein as a base material of biomimetic actuator was investigated in this paper. Silkworm films were prepared from high concentrations of regenerated fibroin in aqueous solution. Films with thickness of about 100 μm were prepared for coating electrodes. The cast silk films were coated by very thin gold electrode on both sides of the film. Tensile test of cast film showed bi-modal trend, which is typical stress-strain relation of polymeric film. As the test of a possible biomimetic actuator, silkworm film actuator provides bending deformations according to the magnitude and frequency of the applied electric filed. Although the present bending deformation of silkworm film actuator is smaller than that of Electro-Active Paper actuator, it provides the possibility of biomimetic actuator.

  19. Exploiting rod technology. Final report

    SciTech Connect

    1990-06-01

    ROD development was proceeding apace until recent budgetary decisions caused funding support for ROD development to be drastically reduced. The funding which was originally provided by DARPA and the Balanced Technology Initiative (BTI) Office has been cut back to zero from $800K. To determine the aeroballistic coefficients of a candidate dart, ARDEC is currently supporting development out of its own 6.2 funds at about $100K. ARDEC has made slow progress toward achieving this end because of failures in the original dart during testing. It appears that the next dart design to be tested will diverge from the original concept visualized by DARPA and Science and Technology Associates (STA). STA, the design engineer, takes exception to these changes on the basis of inappropriate test conditions and insufficient testing. At this time, the full resolution of this issue will be difficult because of the current management structure, which separates the developer (ARDEC) from the designer (STA).

  20. Actuation fluid adapter for hydraulically-actuated electronically-controlled fuel injector and engine using same

    DOEpatents

    Keyster, Eric S.; Merchant, Jack A.

    2002-01-01

    A fuel injector adapter consists of a block defining a pressure communication passage therethrough and an actuation fluid passage. The actuation fluid passage includes three separate branches that open through an outer surface of the block at three separate locations.

  1. Tribe kills fuel rod proposal

    SciTech Connect

    1995-02-13

    This article is a review of nuclear utilities` efforts to find a repository of spent fuel rods. The rejection by the Mescalero Apaches of plans to build a waste repository on tribal lands has left a number of utilities scrambling to find interim solutions. Prairie Island will have to close before the end of the year unless a solution is found, and the Hope Creek/Salem units, exhausting there storage capacity within ten years, are considering dry-cask storage.

  2. 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.

  3. 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.…

  4. MRI-powered Actuators for Robotic Interventions

    PubMed Central

    Vartholomeos, Panagiotis; Qin, Lei; Dupont, Pierre E.

    2012-01-01

    This paper presents a novel actuation technology for robotically assisted MRI-guided interventional procedures. Compact and wireless, the actuators are both powered and controlled by the MRI scanner. The design concept and performance limits are described and derived analytically. Simulation and experiments in a clinical MR scanner are used to validate the analysis and to demonstrate the capability of the approach for needle biopsies. The concepts of actuator locking mechanisms and multi-axis control are also introduced. PMID:22287082

  5. Fluidic self-actuating control assembly

    DOEpatents

    Grantz, Alan L.

    1979-01-01

    A fluidic self-actuating control assembly for use in a reactor wherein no external control inputs are required to actuate (scram) the system. The assembly is constructed to scram upon sensing either a sudden depressurization of reactor inlet flow or a sudden increase in core neutron flux. A fluidic control system senses abnormal flow or neutron flux transients and actuates the system, whereupon assembly coolant flow reverses, forcing absorber balls into the reactor core region.

  6. Direct-drive field actuator motors

    DOEpatents

    Grahn, Allen R.

    1995-01-01

    A high-torque, low speed, positive-drive field actuator motor including a stator carrying at least one field actuator which changes in dimension responsive to application of an energy field, and at least one drive shoe movable by the dimensional changes of the field actuator to contact and move a rotor element with respect to the stator. Various embodiments of the motor are disclosed, and the rotor element may be moved linearly or arcuately.

  7. Direct-drive field actuator motors

    DOEpatents

    Grahn, A.R.

    1995-07-11

    A high-torque, low speed, positive-drive field actuator motor is disclosed including a stator carrying at least one field actuator which changes in dimension responsive to application of an energy field, and at least one drive shoe movable by the dimensional changes of the field actuator to contact and move a rotor element with respect to the stator. Various embodiments of the motor are disclosed, and the rotor element may be moved linearly or arcuately. 37 figs.

  8. Fuel rod assembly to manifold attachment

    DOEpatents

    Donck, Harry A.; Veca, Anthony R.; Snyder, Jr., Harold J.

    1980-01-01

    A fuel element is formed with a plurality of fuel rod assemblies detachably connected to an overhead support with each of the fuel rod assemblies having a gas tight seal with the support to allow internal fission gaseous products to flow without leakage from the fuel rod assemblies into a vent manifold passageway system on the support. The upper ends of the fuel rod assemblies are located at vertically extending openings in the support and upper threaded members are threaded to the fuel rod assemblies to connect the latter to the support. The preferred threaded members are cap nuts having a dome wall encircling an upper threaded end on the fuel rod assembly and having an upper sealing surface for sealing contact with the support. Another and lower seal is achieved by abutting a sealing surface on each fuel rod assembly with the support. A deformable portion on the cap nut locks the latter against inadvertent turning off the fuel rod assembly. Orienting means on the fuel rod and support primarily locates the fuel rods azimuthally for reception of a deforming tool for the cap nut. A cross port in the fuel rod end plug discharges into a sealed annulus within the support, which serves as a circumferential chamber, connecting the manifold gas passageways in the support.

  9. Sliding induced crystallization of metallic glass

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1983-01-01

    Sliding friction and wear experiments, electron microscopy, and diffraction studies were conducted with an Fe67Co18B14Si1 ferrous-base metallic glass in sliding contact with aluminum oxide at room temperature in air. The results indicate that the amorphous alloy can be crystallized during the sliding process. Crystallization of the wear surface causes high friction. Plastic flow occurred on the amorphous alloy with sliding, and the flow film of the alloy transferred to the aluminum oxide surface. Two distinct types of wear debris were observed as a result of sliding: an alloy wear debris, and powdery and whiskery oxide debris. Generation of oxide wear debris particles on an alloy can cause transitions in friction behavior.

  10. Peeling, sliding, pulling and bending

    NASA Astrophysics Data System (ADS)

    Lister, John; Peng, Gunnar

    2015-11-01

    The peeling of an elastic sheet away from thin layer of viscous fluid is a simply-stated and generic problem, that involves complex interactions between the flow and elastic deformation on a range of length scales. Consider an analogue of capillary spreading, where a blister of injected viscous fluid spreads due to tension in the overlying elastic sheet. Here the tension is coupled to the deformation of the sheet, and thus varies in time and space. A key question is whether or not viscous shear stresses ahead of the blister are sufficient to prevent the sheet sliding inwards and relieving the tension. Our asymptotic analysis reveals a dichotomy between fast and slow spreading, and between two-dimensional and axisymmetric spreading. In combination with bending stresses and gravity, which may dominate parts of the flow but not others, there is a plethora of dynamical regimes.

  11. Actuator selection for variable camber foils

    NASA Astrophysics Data System (ADS)

    Madden, John D.

    2004-07-01

    A number of polymer based actuator technologies have emerged over the past decade. How do these compare with traditional actuators and are there applications for which they are appropriate? Some of the answers to these questions are provided by outlining the rationale for employing an electroactive polymer to control hydrodynamic surfaces. The surfaces are sections of propeller blades whose trailing edges are deflected in order to change camber. The objective is to insert the actuators into the blades. High work per unit volume is required of the actuators. The ideal actuator technologies also feature relatively large strains in order to deflect the trailing edges with minimal mechanical amplification. It is argued that the high work densities, flexibility in shaping and the ability to hold a force without expending energy (catch state) provide electroactive polymers with advantages over electromagnetic actuators, which also lack the torque to directly drive the blade deflection. Candidate actuators are compared, including electroactive polymers, shape memory alloys, magnetostrictives and traditional piezoceramics. Selections are made on the bases of work density, strain, existence of a catch state, drive voltage and cost. It is suggested that conducting polymer actuators are best suited for the variable camber application. It is also argued that in general electroactive polymers are well-suited for applications in which actuator volume or mass are very limited, catch states are desired, cycle life is moderate to low, or noise cannot be tolerated. Some electroactive polymers also feature low voltage operation, and may be biocompatible.

  12. Bucky gel actuators optimization towards haptic applications

    NASA Astrophysics Data System (ADS)

    Bubak, Grzegorz; Ansaldo, Alberto; Ceseracciu, Luca; Hata, Kenji; Ricci, Davide

    2014-03-01

    An ideal plastic actuator for haptic applications should generate a relatively large displacement (minimum 0.2-0.6 mm, force (~50 mN/cm2) and a fast actuation response to the applied voltage. Although many different types of flexible, plastic actuators based on electroactive polymers (EAP) are currently under investigation, the ionic EAPs are the only ones that can be operated at low voltage. This property makes them suitable for applications that require inherently safe actuators. Among the ionic EAPs, bucky gel based actuators are very promising. Bucky gel is a physical gel made by grounding imidazolium ionic liquids with carbon nanotubes, which can then be incorporated in a polymeric composite matrix to prepare the active electrode layers of linear and bending actuators. Anyhow, many conflicting factors have to be balanced to obtain required performance. In order to produce high force a large stiffness is preferable but this limits the displacement. Moreover, the bigger the active electrode the larger the force. However the thicker an actuator is, the slower the charging process becomes (it is diffusion limited). In order to increase the charging speed a thin electrolyte would be desirable, but this increases the probability of pinholes and device failure. In this paper we will present how different approaches in electrolyte and electrode preparation influence actuator performance and properties taking particularly into account the device ionic conductivity (which influences the charging speed) and the electrode surface resistance (which influences both the recruitment of the whole actuator length and its speed).

  13. The Mariner Mars 1971 gimbal actuator

    NASA Technical Reports Server (NTRS)

    Perkins, G. S.

    1971-01-01

    The actuator that will point the gimbaled engine, thus performing the autopilot actuation function for the Mariner Mars 1971 spacecraft, is described. The gimbaled engine has two axes of freedom, providing two-axis control to the spacecraft. Motion for the two axes is provided by identical and interchangeable actuators-gearless electromechanical linear servomechanisms. Each actuator is designed to have a long service life in the space environment and to be able to function at speeds ranging from hours per cycle to cycles per second.

  14. Two position optical element actuator device

    DOEpatents

    Holdener, Fred R.; Boyd, Robert D.

    2002-01-01

    The present invention is a two position optical element actuator device utilizing a powered means to hold an actuation arm, to which an optical element is attached, in a first position. A non-powered means drives the actuation arm to a second position, when the powered means ceases to receive power. The optical element may be a electromagnetic (EM) radiation or particle source, an instrument, or EM radiation or particle transmissive, reflective or absorptive elements. A bearing is used to transfer motion and smoothly transition the actuation arm from the first to second position.

  15. Bi-stable optical element actuator device

    DOEpatents

    Holdener, Fred R.; Boyd, Robert D.

    2002-01-01

    The present invention is a bistable optical element actuator device utilizing a powered means to move an actuation arm, to which an optical element is attached, between two stable positions. A non-powered means holds the actuation arm in either of the two stable positions. The optical element may be a electromagnetic (EM) radiation or particle source, an instrument, or EM radiation or particle transmissive reflective or absorptive elements. A bearing is used to transfer motion and smoothly transition the actuation arm between the two stable positions.

  16. Surface micromachined sensors and actuators

    SciTech Connect

    Sniegowski, J.J.

    1995-08-01

    A description of a three-level mechanical polysilicon surface-micromachining technology including a discussion of the advantages of this level of process complexity is presented. This technology is capable of forming mechanical elements ranging from simple cantilevered beams to complex, interconnected, interactive, microactuated micromechanisms. The inclusion of a third deposited layer of mechanical polysilicon greatly extends the degree of complexity available for micromechanism design. Additional features of the Sandia three-level process include the use of Chemical-Mechanical Polishing (CMP) for planarization, and the integration of micromechanics with the Sandia CMOS circuit process. The latter effort includes a CMOS-first, tungsten metallization process to allow the CMOS electronics to withstand high-temperature micromechanical processing. Alternatively, a novel micromechanics-first approach wherein the micromechanical devices are processed first in a well below the surface of the CMOS starting material followed by the standard, aluminum metallization CMOS process is also being pursued. Following the description of the polysilicon surface micromachining are examples of the major sensor and actuator projects based on this technology at the Microelectronics Development Laboratory (MDL) at Sandia National Laboratories. Efforts at the MDL are concentrated in the technology of surface micromachining due to the availability of and compatibility with standard CMOS processes. The primary sensors discussed are a silicon nitride membrane pressure sensor, hot polysilicon filaments for calorimetric gas sensing, and a smart hydrogen sensor. Examples of actuation mechanisms coupled to external devices are also presented. These actuators utilize the three-level process (plus an additional passive level) and employ either surface tension or electrostatic forces.

  17. Nonlinear dynamic modeling for smart material electro-hydraulic actuator development

    NASA Astrophysics Data System (ADS)

    Larson, John P.; Dapino, Marcelo J.

    2013-03-01

    Smart material electro-hydraulic actuators use hydraulic rectification by one-way check valves to amplify the motion of smart materials, such as magnetostrictives and piezoelectrics, in order to create compact, lightweight actuators. A piston pump driven by a smart material is combined with a hydraulic cylinder to form a self-contained, power-by-wire actuator that can be used in place of a conventional hydraulic system without the need for hydraulic lines and a centralized pump. The performance of an experimental actuator driven by a 12.7 mm diameter, 114 mm length Terfenol-D rod is evaluated over a range of applied input frequencies, loads, and currents. The peak performance achieved is 37 W, moving a 220 N load at a rate of 17 cm/s and producing a blocked pressure of 12.5 MPa. Additional tests are conducted to quantify the dynamic behavior of the one-way reed valves using a scanning laser vibrometer to identify the frequency response of the reeds and the effect of the valve seat and fluid mass loading. A lumped-parameter model is developed for the system that includes valve inertia and fluid response nonlinearities, and the model results are compared with the experimental data.

  18. Experimental Study on the Influence of the Supporting Condition and Rod Motion on the Fuel Fretting Damage

    SciTech Connect

    Kim, Hyung-Kyu; Lee, Young-Ho

    2007-07-01

    Present study focuses on the influence of a supporting condition and a rod motion on a fuel fretting wear through experiments using a self-developed wear simulator, which was presented at the Water Reactor Fuel Performance Meeting, Kyoto Japan in 2005. In the experiment, a fuel rod specimen of two span lengths is vibrated by two perpendicularly aligned electromagnetic actuators. Both ends of the rod specimen are supported with a positive contact force and a variation of the supporting condition is simulated by moving each of the four grid strap specimens constituting a center grid cell. As for the supporting condition, 0.1 mm gap and 10 N force are used; a circular and a diagonal traces are applied for the rod motion. The contact shape of the spring/dimple is concave, to try and increase the contact area. Both the spring/dimple and fuel rod specimens were fabricated from the as-received materials (zirconium alloy) for a commercial fuel assembly. Experiments are carried out under a room temperature and distilled water condition. Experiment of each condition is carried out for 72 hours. Wear volume, area and depth on the cladding tubes are examined. As a result, the present concave shaped spring/dimple causes less wear when the rod moves in a circular manner than a diagonal one if there is a positive contact force (10 N). However, a diagonal motion causes more wear when a gap (0.1 mm) exists. Wear amount at the spring and dimple is influenced by the location of them and the rod motion. It is found that the wear is concentrated at the contact edges between the spring/dimple and rods due to the contact shape. The influence of the rod motion on the worn area and its shape is also discussed. (authors)

  19. Dielectric elastomer actuators for adaptive photonic microsystems

    NASA Astrophysics Data System (ADS)

    Heimann, Marcus; Schröder, Henning; Marx, Sebastian; Lang, Klaus-Dieter

    2013-03-01

    Various applications in the field of photonic microsystems for Dielectric Elastomer Actuators (DEA) were shown with this research. DEA belong to the class of Electro Active Polymers (EAP) and have the potential to substitute common technologies like piezoelectric actuators. DEAs offers several advantages like compact and variable shapes, large actuation ranges and cost efficient production processes that have to be emphasized. For the market of adaptive photonic microsystems especially area actuators are very suitable. They can be used e.g. as tuneable lens, mirror or grating component and tool for optical fiber alignment. These area actuators have a similar structure like a capacitor. They consist of three layers, two electrode layers on top and bottom and one dielectric layer in the center. The dielectric layer is made of a deformable and prestretched elastomer film. When applying a voltage between both electrode layers the thickness of the dielectric film is compressed and the actuator is displaced in the plane. The use of material compositions like a polymer matrix with graphite, carbon nano particles or carbon nano tubes as well as thin metal films for the electrodes were studied. The paper presents results on suitable dielectric and electrode materials, actuator geometries and respective adaptive photonic components. The manufacturing process of area actuators is described in detail. As a basic size of the area actuators (20 × 20) mm2 were chosen. Onto the produced area actuators polymer lenses or mirrors were assembled. The deflection of the optical beam path is calculated with optical simulations and measured at the prepared adaptive optical components. Static actuations of about +/-15 μm are achieved when applying a voltage of 200 V. Also the function of a tuneable beam splitter is demonstrated to show further applications.

  20. 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

  1. An updated nuclear criticality slide rule

    SciTech Connect

    Hopper, C.M.; Broadhead, B.L.

    1998-04-01

    This Volume 2 contains the functional version of the updated nuclear criticality slide rule (more accurately, sliding graphs) that is referenced in An Updated Nuclear Criticality Slide Rule: Technical Basis, NUREG/CR-6504, Vol. 1 (ORNL/TM-13322/V1). This functional slide rule provides a readily usable {open_quotes}in-hand{close_quotes} method for estimating pertinent nuclear criticality accident information from sliding graphs, thereby permitting (1) the rapid estimation of pertinent criticality accident information without laborious or sophisticated calculations in a nuclear criticality emergency situation, (2) the appraisal of potential fission yields and external personnel radiation exposures for facility safety analyses, and (3) a technical basis for emergency preparedness and training programs at nonreactor nuclear facilities. The slide rule permits the estimation of neutron and gamma dose rates and integrated doses based upon estimated fission yields, distance from the fission source, and time-after criticality accidents for five different critical systems. Another sliding graph permits the estimation of critical solution fission yields based upon fissile material concentration, critical vessel geometry, and solution addition rate. Another graph provides neutron and gamma dose-reduction factors for water, steel, and concrete. Graphs from historic documents are provided as references for estimating critical parameters of various fissile material systems. Conversion factors for various English and metric units are provided for quick reference.

  2. NASA pyrotechnically actuated systems program

    NASA Technical Reports Server (NTRS)

    Schulze, Norman R.

    1993-01-01

    The Office of Safety and Mission Quality initiated a Pyrotechnically Actuated Systems (PAS) Program in FY-92 to address problems experienced with pyrotechnically actuated systems and devices used both on the ground and in flight. The PAS Program will provide the technical basis for NASA's projects to incorporate new technological developments in operational systems. The program will accomplish that objective by developing/testing current and new hardware designs for flight applications and by providing a pyrotechnic data base. This marks the first applied pyrotechnic technology program funded by NASA to address pyrotechnic issues. The PAS Program has been structured to address the results of a survey of pyrotechnic device and system problems with the goal of alleviating or minimizing their risks. Major program initiatives include the development of a Laser Initiated Ordnance System, a pyrotechnic systems data base, NASA Standard Initiator model, a NASA Standard Linear Separation System and a NASA Standard Gas Generator. The PAS Program sponsors annual aerospace pyrotechnic systems workshops.

  3. A thermopneumatically actuated bistable microvalve

    NASA Astrophysics Data System (ADS)

    Yang, Bocong; Wang, Boxiong; Schomburg, Werner Karl

    2010-09-01

    A bistable polymer microvalve with a thermopneumatic actuator has been developed. The microvalve was fabricated by micro milling of a polymer combined with sputtering and photolithography. The valve comprises two 2/2-way valves which are alternately switched such that they can be connected to serve as a 3/2-way valve. Two permanent magnets work with a movable soft magnet to keep the valve in its current state, resulting in bistable switching with a minimum energy of 320 mJ. An air flow rate of 1.36 L min-1 is achieved at 20 °C with a pressure difference of 200 kPa. No leakage is observed up to a differential pressure of 350 kPa. Flowing and switching performances were also tested at different temperatures. Sealing the flow channels from the actuator chamber makes the valve less sensitive to the temperature and other properties of the fluid to be switched. An initial gap between the valve seat and the silicone sealing membrane at least reduces the sticking problem. Switching time is found to be significantly influenced by the thickness of the heating membrane. With an 8 µm thick heating membrane, a response time of 10 ms can be achieved.

  4. Optimization of Actuating Origami Networks

    NASA Astrophysics Data System (ADS)

    Buskohl, Philip; Fuchi, Kazuko; Bazzan, Giorgio; Joo, James; Gregory, Reich; Vaia, Richard

    2015-03-01

    Origami structures morph between 2D and 3D conformations along predetermined fold lines that efficiently program the form, function and mobility of the structure. By leveraging design concepts from action origami, a subset of origami art focused on kinematic mechanisms, reversible folding patterns for applications such as solar array packaging, tunable antennae, and deployable sensing platforms may be designed. However, the enormity of the design space and the need to identify the requisite actuation forces within the structure places a severe limitation on design strategies based on intuition and geometry alone. The present work proposes a topology optimization method, using truss and frame element analysis, to distribute foldline mechanical properties within a reference crease pattern. Known actuating patterns are placed within a reference grid and the optimizer adjusts the fold stiffness of the network to optimally connect them. Design objectives may include a target motion, stress level, or mechanical energy distribution. Results include the validation of known action origami structures and their optimal connectivity within a larger network. This design suite offers an important step toward systematic incorporation of origami design concepts into new, novel and reconfigurable engineering devices. This research is supported under the Air Force Office of Scientific Research (AFOSR) funding, LRIR 13RQ02COR.

  5. Experiments and models of low Reynolds number flows generated by a precessing rod over a plane

    NASA Astrophysics Data System (ADS)

    Martindale, James; Camassa, Roberto; McLaughlin, Richard M.; Vicci, Leandra; Zhao, Longhua; UNC NSF RTG Fluids Team Collaboration

    2012-11-01

    Slender body asymptotics and experiments are developed to emulate dynamics biological interest such as primary cilia in developing embryos. Experiments are performed using high viscosity silicon oil with magnetically actuated precessing rod in a table-top setup. Stereoscopic Lagrangian tracking show quantified long-time agreement with an appropriately imaged slender body theory to enforce the no-slip boundary condition of the floor. In contrast, breaking symmetry by a bent rod creates additional flow components which destroy quantitative short time agreement with the theory while maintaining its qualitative features including the creation of large scale Lagrangian tori. Higher order asymptotic corrections are implemented and compared in an attempt to restore quantitative predictability. Direct comparison with 3D stereoscopic PIV measurements will be presented. NSF RTG DMS-0502266, NSF RTG DMS-0943851, and NSF DMS-1009750.

  6. An Analytical Study of Fuzzy Control of a Flexible Rod Mechanism

    NASA Astrophysics Data System (ADS)

    Beale, D.; Lee, S. W.; Boghiu, D.

    1998-02-01

    The non-linear nature of very high speed, flexible rod mechanisms has been previously confirmed, both experimentally and analytically in reference [1]. Therefore, effective control system design for flexible mechanisms operating at very high speeds must consider the non-linearities when designing a controller for very high speeds. Active control via fuzzy logic is assessed as means to suppress the elastic transverse bending vibration of a flexible rod of a slider crank mechanism. Several pairs of piezoelectric elements are used to provide the control action. Sensor output of deflection is fed to the fuzzy controller, which determines the voltage input to the actuators. A three mode approximation is used in the simulation study. Computer simulation shows that fuzzy control can be used to suppress bending vibrations at high speeds, and even at speeds where the uncontrolled response would be unstable.

  7. SlideToolkit: An Assistive Toolset for the Histological Quantification of Whole Slide Images

    PubMed Central

    Nelissen, Bastiaan G. L.; van Herwaarden, Joost A.; Moll, Frans L.; van Diest, Paul J.; Pasterkamp, Gerard

    2014-01-01

    The demand for accurate and reproducible phenotyping of a disease trait increases with the rising number of biobanks and genome wide association studies. Detailed analysis of histology is a powerful way of phenotyping human tissues. Nonetheless, purely visual assessment of histological slides is time-consuming and liable to sampling variation and optical illusions and thereby observer variation, and external validation may be cumbersome. Therefore, within our own biobank, computerized quantification of digitized histological slides is often preferred as a more precise and reproducible, and sometimes more sensitive approach. Relatively few free toolkits are, however, available for fully digitized microscopic slides, usually known as whole slides images. In order to comply with this need, we developed the slideToolkit as a fast method to handle large quantities of low contrast whole slides images using advanced cell detecting algorithms. The slideToolkit has been developed for modern personal computers and high-performance clusters (HPCs) and is available as an open-source project on github.com. We here illustrate the power of slideToolkit by a repeated measurement of 303 digital slides containing CD3 stained (DAB) abdominal aortic aneurysm tissue from a tissue biobank. Our workflow consists of four consecutive steps. In the first step (acquisition), whole slide images are collected and converted to TIFF files. In the second step (preparation), files are organized. The third step (tiles), creates multiple manageable tiles to count. In the fourth step (analysis), tissue is analyzed and results are stored in a data set. Using this method, two consecutive measurements of 303 slides showed an intraclass correlation of 0.99. In conclusion, slideToolkit provides a free, powerful and versatile collection of tools for automated feature analysis of whole slide images to create reproducible and meaningful phenotypic data sets. PMID:25372389

  8. Silicon Membrane Mirrors with Electrostatic Shape Actuators

    NASA Technical Reports Server (NTRS)

    Yang, Eui-Hyeok

    2003-01-01

    Efforts are under way to develop deformable mirrors equipped with microscopic electrostatic actuators that would be used to maintain their reflective surfaces in precise shapes required for their intended applications. Unlike actuators that depend on properties of materials (e.g., piezoelectric and electrostrictive actuators), electrostatic actuators are effective over a wide temperature range. A mirror of the present type would be denoted a MEMSDM (for microelectromechanical system deformable mirror). The reflective surface of such a mirror would be formed on a single-crystal silicon membrane that would be attached by posts to a silicon actuator membrane that would, in turn, be attached by posts to a rigid silicon base (see figure). The actuator membrane would serve as the upper electrode of a capacitor. Multiple lower electrodes, each occupying a conveniently small fraction of the total area, would be formed on an electrically insulating oxide layer on the base, thereby defining a multiplicity of actuator pixels. The actuator membrane would be corrugated in a pattern that would impart mechanical compliance needed for relaxation of operational and fabrication-induced stresses and to minimize the degree of nonlinearity of deformations. The compliance afforded by the corrugations would also help to minimize the undesired coupling of deformations between adjacent pixels (a practical goal being to keep the influence coefficient between adjacent pixels below 10 percent).

  9. Improvements In Ball-Screw Linear Actuators

    NASA Technical Reports Server (NTRS)

    Iskenderian, Theodore; Joffe, Benjamin; Summers, Robert

    1996-01-01

    Report describes modifications of design of type of ball-screw linear actuator driven by dc motor, with linear-displacement feedback via linear variable-differential transformer (LVDT). Actuators used to position spacecraft engines to direct thrust. Modifications directed toward ensuring reliable and predictable operation during planned 12-year cruise and interval of hard use at end of cruise.

  10. Integrated piezoelectric actuators in deep drawing tools

    NASA Astrophysics Data System (ADS)

    Neugebauer, R.; Mainda, P.; Drossel, W.-G.; Kerschner, M.; Wolf, K.

    2011-04-01

    The production of car body panels are defective in succession of process fluctuations. Thus the produced car body panel can be precise or damaged. To reduce the error rate, an intelligent deep drawing tool was developed at the Fraunhofer Institute for Machine Tools and Forming Technology IWU in cooperation with Audi and Volkswagen. Mechatronic components in a closed-loop control is the main differentiating factor between an intelligent and a conventional deep drawing tool. In correlation with sensors for process monitoring, the intelligent tool consists of piezoelectric actuators to actuate the deep drawing process. By enabling the usage of sensors and actuators at the die, the forming tool transform to a smart structure. The interface between sensors and actuators will be realized with a closed-loop control. The content of this research will present the experimental results with the piezoelectric actuator. For the analysis a production-oriented forming tool with all automotive requirements were used. The disposed actuators are monolithic multilayer actuators of the piezo injector system. In order to achieve required force, the actuators are combined in a cluster. The cluster is redundant and economical. In addition to the detailed assembly structures, this research will highlight intensive analysis with the intelligent deep drawing tool.

  11. High temperature control rod assembly

    DOEpatents

    Vollman, Russell E.

    1991-01-01

    A high temperature nuclear control rod assembly comprises a plurality of substantially cylindrical segments flexibly joined together in succession by ball joints. The segments are made of a high temperature graphite or carbon-carbon composite. The segment includes a hollow cylindrical sleeve which has an opening for receiving neutron-absorbing material in the form of pellets or compacted rings. The sleeve has a threaded sleeve bore and outer threaded surface. A cylindrical support post has a threaded shaft at one end which is threadably engaged with the sleeve bore to rigidly couple the support post to the sleeve. The other end of the post is formed with a ball portion. A hollow cylindrical collar has an inner threaded surface engageable with the outer threaded surface of the sleeve to rigidly couple the collar to the sleeve. the collar also has a socket portion which cooperates with the ball portion to flexibly connect segments together to form a ball and socket-type joint. In another embodiment, the segment comprises a support member which has a threaded shaft portion and a ball surface portion. The threaded shaft portion is engageable with an inner threaded surface of a ring for rigidly coupling the support member to the ring. The ring in turn has an outer surface at one end which is threadably engageably with a hollow cylindrical sleeve. The other end of the sleeve is formed with a socket portion for engagement with a ball portion of the support member. In yet another embodiment, a secondary rod is slidably inserted in a hollow channel through the center of the segment to provide additional strength. A method for controlling a nuclear reactor utilizing the control rod assembly is also included.

  12. Actuator lifetime predictions for Ni60Ti40 shape memory alloy plate actuators

    NASA Astrophysics Data System (ADS)

    Wheeler, Robert; Ottmers, Cade; Hewling, Brett; Lagoudas, Dimitris

    2016-04-01

    Shape memory alloys (SMAs), due to their ability to repeatedly recover substantial deformations under applied mechanical loading, have the potential to impact the aerospace, automotive, biomedical, and energy industries as weight and volume saving replacements for conventional actuators. While numerous applications of SMA actuators have been flight tested and can be found in industrial applications, these actuators are generally limited to non-critical components, are not widely implemented and frequently one-off designs, and are generally overdesigned due to a lack of understanding of the effect of the loading path on the fatigue life and the lack of an accurate method of predicting actuator lifetimes. Previous efforts have been effective at predicting actuator lifetimes for isobaric dogbone test specimens. This study builds on previous work and investigates the actuation fatigue response of plate actuators with various stress concentrations through the use of digital image correlation and finite element simulations.

  13. 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

  14. 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.

  15. Electroactive Polymer (EAP) Actuation of Mechanisms and Robotic Devices

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Y.; Leary, S.; Harrison, J.; Smith, J.

    1999-01-01

    Actuators are responsible to the operative capability of manipulation systems and robots. In recent years, electroactive polymers (EAP) have emerged as potential alternative to conventional actuators.

  16. Design and Control of a Proof-of-Concept Active Jet Engine Intake Using Shape Memory Alloy Actuators

    NASA Technical Reports Server (NTRS)

    Song, Gangbing; Ma, Ning; Penney, Nicholas; Barr, Todd; Lee, Ho-Jun; Arnold, Steven M.

    2004-01-01

    The design and control of a novel proof-of-concept active jet engine intake using Nickel-Titanium (Ni-Ti or Nitinol) shape memory alloy (SMA) wire actuators is used to demonstrate the potential of an adaptive intake to improve the fuel efficiency of a jet engine. The Nitinol SMA material is selected for this research due to the material's ability to generate large strains of up to 5 percent for repeated operations, a high power-to-weight ratio, electrical resistive actuation, and easy fabrication into a variety of shapes. The proof-of-concept engine intake employs an overlapping leaf design arranged in a concentric configuration. Each leaf is mounted on a supporting bar that rotates upon actuation by SMA wires electrical resistive heating. Feedback control is enabled through the use of a laser range sensor to detect the movement of a leaf and determine the radius of the intake area. Due to the hysteresis behavior inherent in SMAs, a nonlinear robust controller is used to direct the SMA wire actuation. The controller design utilizes the sliding-mode approach to compensate for the nonlinearities associated with the SMA actuator. Feedback control experiments conducted on a fabricated proof-of-concept model have demonstrated the capability to precisely control the intake area and achieve up to a 25 percent reduction in intake area. The experiments demonstrate the feasibility of engine intake area control using the proposed design.

  17. Self-assembly of rod-coil-rod ABA-type triblock copolymers.

    PubMed

    Chen, Ji-Zhong; Sun, Zhao-Yan; Zhang, Cheng-Xiang; An, Li-Jia; Tong, Zhen

    2008-02-21

    Self-assembled behavior of symmetric ABA rod-coil-rod triblock copolymer melts is studied by applying self-consistent-field lattice techniques in three-dimensional space. The phase diagram is constructed to understand the effects of the chain architecture on the self-assembled behavior. Four stable structures are observed for the ABA rod-coil-rod triblock, i.e., spherelike, lamellar, gyroidlike, and cylindrical structures. Different from AB rod-coil diblock and BAB coil-rod-coil triblock copolymers, the lamellar structure observed in ABA rod-coil-rod triblock copolymer melts is not stable for high volume fraction of the rod component (f(rod)=0.8), which is attributed to the intramolecular interactions between the two rod blocks of the polymer chain. When 0.3rod)<0.7, the intramolecular interactions between the two rigid blocks of the polymer chain are decrease, which results in the occurrence of some interesting metastable mixed structures. These structures have not been observed in polymers containing only one rod block, such as a lamellar-alt-lamellar structure. The results are expected to provide guidance for the design of microstructures in experiments. PMID:18298171

  18. Conducting IPN actuators for biomimetic vision system

    NASA Astrophysics Data System (ADS)

    Festin, Nicolas; Plesse, Cedric; Chevrot, Claude; Teyssié, Dominique; Pirim, Patrick; Vidal, Frederic

    2011-04-01

    In recent years, many studies on electroactive polymer (EAP) actuators have been reported. One promising technology is the elaboration of electronic conducting polymers based actuators with Interpenetrating Polymer Networks (IPNs) architecture. Their many advantageous properties as low working voltage, light weight and high lifetime (several million cycles) make them very attractive for various applications including robotics. Our laboratory recently synthesized new conducting IPN actuators based on high molecular Nitrile Butadiene Rubber, poly(ethylene oxide) derivative and poly(3,4-ethylenedioxithiophene). The presence of the elastomer greatly improves the actuator performances such as mechanical resistance and output force. In this article we present the IPN and actuator synthesis, characterizations and design allowing their integration in a biomimetic vision system.

  19. Lead magnesium niobate actuator for micropositioning

    DOEpatents

    Swift, C.D.; Bergum, J.W.

    1994-10-25

    An improved lead magnesium niobate actuator is disclosed comprising a cylindrical lead magnesium niobate crystal stack mounted in a cylindrical casing wherein a bias means, such as one or more belleville washers, is located between one end of the crystal stack and a partially closed end of the casing; and adjustment means are provided which bear against the opposite end of the crystal stack, whereby an adjustable compressive force is constantly applied against the crystal stack, whether the crystal stack is actuated in an extended position, or is in an unactuated contracted position. In a preferred embodiment, cooling ports are provided for the circulation of coolant in the actuator to cool the crystal stack, and provision is made for removal and replacement of the crystal stack without disconnecting the actuator from the external device being actuated. 3 figs.

  20. Lead magnesium niobate actuator for micropositioning

    DOEpatents

    Swift, Charles D.; Bergum, John W.

    1994-01-01

    An improved lead magnesium niobate actuator is disclosed comprising a cylindrical lead magnesium niobate crystal stack mounted in a cylindrical casing wherein a bias means, such as one or more belleville washers, is located between one end of the crystal stack and a partially closed end of the casing; and adjustment means are provided which bear against the opposite end of the crystal stack, whereby an adjustable compressive force is constantly applied against the crystal stack, whether the crystal stack is actuated in an extended position, or is in an unactuated contracted position. In a preferred embodiment, cooling ports are provided for the circulation of coolant in the actuator to cool the crystal stack, and provision is made for removal and replacement of the crystal stack without disconnecting the actuator from the external device being actuated.

  1. Piezoelectric Actuator/Sensor Technology at Rockwell

    NASA Technical Reports Server (NTRS)

    Neurgaonkar, Ratnakar R.

    1996-01-01

    We describe the state-of-the art of piezoelectric materials based on perovskite and tungsten bronze families for sensor, actuator and smart structure applications. The microstructural defects in these materials have been eliminated to a large extent and the resulting materials exhibit exceedingly high performance for various applications. The performance of Rockwell actuators/sensors is at least 3 times better than commercially available products. These high performance actuators are being incorporated into various applications including, DOD, NASA and commercial. The multilayer actuator stacks fabricated from our piezoceramics are advantageous for sensing and high capacitance applications. In this presentation, we will describe the use of our high performance piezo-ceramics for actuators and sensors, including multilayer stacks and composite structures.

  2. Electrostatic micromembrane actuator arrays as motion generator

    NASA Astrophysics Data System (ADS)

    Wu, X. T.; Hui, J.; Young, M.; Kayatta, P.; Wong, J.; Kennith, D.; Zhe, J.; Warde, C.

    2004-05-01

    A rigid-body motion generator based on an array of micromembrane actuators is described. Unlike previous microelectromechanical systems (MEMS) techniques, the architecture employs a large number (typically greater than 1000) of micron-sized (10-200 μm) membrane actuators to simultaneously generate the displacement of a large rigid body, such as a conventional optical mirror. For optical applications, the approach provides optical design freedom of MEMS mirrors by enabling large-aperture mirrors to be driven electrostatically by MEMS actuators. The micromembrane actuator arrays have been built using a stacked architecture similar to that employed in the Multiuser MEMS Process (MUMPS), and the motion transfer from the arrayed micron-sized actuators to macro-sized components was demonstrated.

  3. MEMS Electrostatic Actuation in Conducting Biological Media

    PubMed Central

    Mukundan, Vikram; Pruitt, Beth L.

    2009-01-01

    We present design and experimental implementation of electrostatic comb-drive actuators in solutions of high conductivity relevant for biological cells. The actuators are operated in the frequency range 1–10 MHz in ionic and biological cell culture media, with ionic strengths up to 150 mMoles/L. Typical displacement is 3.5 μm at an applied peak-to-peak signal of 5V. Two different actuation schemes are presented and tested for performance at high frequency. A differential drive design is demonstrated to overcome the attenuation due to losses in parasitic impedances. The frequency dependence of the electrostatic force has been characterized in media of different ionic strengths. Circuit models for the electric double layer phenomena are used to understand and predict the actuator behavior. The actuator is integrated into a planar force sensing system to measure the stiffness of cells cultured on suspended structures. PMID:20161046

  4. Genetic Algorithm Approaches for Actuator Placement

    NASA Technical Reports Server (NTRS)

    Crossley, William A.

    2000-01-01

    This research investigated genetic algorithm approaches for smart actuator placement to provide aircraft maneuverability without requiring hinged flaps or other control surfaces. The effort supported goals of the Multidisciplinary Design Optimization focus efforts in NASA's Aircraft au program. This work helped to properly identify various aspects of the genetic algorithm operators and parameters that allow for placement of discrete control actuators/effectors. An improved problem definition, including better definition of the objective function and constraints, resulted from this research effort. The work conducted for this research used a geometrically simple wing model; however, an increasing number of potential actuator placement locations were incorporated to illustrate the ability of the GA to determine promising actuator placement arrangements. This effort's major result is a useful genetic algorithm-based approach to assist in the discrete actuator/effector placement problem.

  5. Reactor control rod timing system. [LMFBR

    DOEpatents

    Wu, P.T.K.

    1980-03-18

    A fluid driven jet-edge whistle timing system is described for control rods of a nuclear reactor for producing real-time detection of the timing of each control rod in its scram operation. An important parameter in reactor safety, particularly for liquid metal fast breeder reactors (LMFBR), is the time deviation between the time the control rod is released and the time the rod actually reaches the down position. The whistle has a nearly pure tone signal with center frequency (above 100 kHz) far above the frequency band in which the energy of the background noise is concentrated. Each control rod can be fitted with a whistle with a different frequency so that there is no ambiguity in differentiating the signal from each control rod.

  6. Measurement of oil film thickness for application to elastomeric Stirling engine rod seals

    NASA Technical Reports Server (NTRS)

    Krauter, A. I.

    1981-01-01

    The rod seal in the Stirling engine has the function of separating high pressure gas from low or ambient pressure oil. An experimental apparatus was designed to measure the oil film thickness distribution for an elastomeric seal in a reciprocating application. Tests were conducted on commercial elastomeric seals having a 76 mm rod and a 3.8 mm axial width. Test conditions included 70 and 90 seal durometers, a sliding velocity of 0.8 m/sec, and a zero pressure gradient across the seal. An acrylic cylinder and a typical synthetic base automotive lubricant were used. The experimental results showed that the effect of seal hardness on the oil film thickness is considerable. A comparison between analytical and experimental oil film profiles for an elastomeric seal during relatively high speed reciprocating motion showed an overall qualitative agreement.

  7. Color standardization in whole slide imaging using a color calibration slide

    PubMed Central

    Bautista, Pinky A.; Hashimoto, Noriaki; Yagi, Yukako

    2014-01-01

    Background: Color consistency in histology images is still an issue in digital pathology. Different imaging systems reproduced the colors of a histological slide differently. Materials and Methods: Color correction was implemented using the color information of the nine color patches of a color calibration slide. The inherent spectral colors of these patches along with their scanned colors were used to derive a color correction matrix whose coefficients were used to convert the pixels’ colors to their target colors. Results: There was a significant reduction in the CIELAB color difference, between images of the same H & E histological slide produced by two different whole slide scanners by 3.42 units, P < 0.001 at 95% confidence level. Conclusion: Color variations in histological images brought about by whole slide scanning can be effectively normalized with the use of the color calibration slide. PMID:24672739

  8. Growth and Morphology of Rod Eutectics

    SciTech Connect

    Jing Teng; Shan Liu; R. Trivedi

    2008-03-17

    The formation of rod eutectic microstructure is investigated systematically in a succinonitrile-camphor alloy of eutectic composition by using the directional solidification technique. A new rod eutectic configuration is observed in which the rods form with elliptical cylindrical shape. Two different orientations of the ellipse are observed that differ by a 90{sup o} rotation such that the major and the minor axes are interchanged. Critical experiments in thin samples, where a single layer of rods forms, show that the spacing and orientation of the elliptic rods are governed by the growth rate and the sample thickness. In thicker samples, multi layers of rods form with circular cross-section and the scaling law between the spacing and velocity predicted by the Jackson and Hunt model is validated. A theoretical model is developed for a two-dimensional array of elliptical rods that are arranged in a hexagonal or a square array, and the results are shown to be consistent with the experimental observations. The model of elliptic rods is also shown to reduce to that for the circular rod eutectic when the lengths of the two axes are equal, and to the lamellar eutectic model when one of the axes is much larger than the other one.

  9. The directional sensitivity of retinal rods.

    PubMed Central

    Alpern, M; Ching, C C; Kitahara, K

    1983-01-01

    Rod field sensitivity, 10-S(r) (i.e. the reciprocal of the radiance of a background required for 10-fold elevation of rod threshold) was measured for monochromatic backgrounds traversing the pupil at various points (r) on three subjects. The wave-length dependency of the directional sensitivities of the three foveal cone mechanisms of the principal subject have been reported previously (Alpern & Kitahara, 1983). Rods, as cones, are less sensitive to obliquely incident, than to normally incident backgrounds. At the pupil margin (4 mm) the effect is between 0.368 and 0.976 log10 units smaller for rods. After correction for losses by corneal reflexion and by absorption in the lens, S(r) for rods is reasonably described by the parabolic equation used by Stiles (1937) to quantify the directional sensitivity of cones. The small effect for rods precludes a description as consistently precise as this equation provides for cones. The steepness of the parabolic curve best fitting the directional sensitivity data of the rods of the principal subject was independent of background wave number. For a second subject, whose rods are supposed to be smaller, it was directly proportional to the square of that wave number. The latter is the expectation if the directional sensitivity of this subject's rods were determined by principles outlined in the diffraction theory of Simon (1970). PMID:6644624

  10. Evaporation of sessile drops containing colloidal rods: coffee-ring and order-disorder transition.

    PubMed

    Dugyala, Venkateshwar Rao; Basavaraj, Madivala G

    2015-03-01

    Liquid drops containing insoluble solutes when dried on solid substrates leave distinct ring-like deposits at the periphery or along the three-phase contact line-a phenomena popularly known as the coffee-ring or the coffee stain effect. The formation of such rings as well as their suppression is shown to have applications in particle separation and disease diagnostics. We present an experimental study of the evaporation of sessile drops containing silica rods to elucidate the structural arrangement of particles in the ring, an effect of the addition of surfactant and salt. To this end, the evaporation of aqueous sessile drops containing model rod-like silica particles of aspect ratio ranging from ∼4 to 15 on a glass slide is studied. We first show that when the conditions such as (1) solvent evaporation, (2) nonzero contact angle, (3) contact line pinning, (4) no surface tension gradient driven flow, and (5) repulsive particle-particle/particle-substrate interactions, that are necessary for the formation of the coffee-ring are met, the suspension drops containing silica rods upon evaporation leave a ring-like deposit. A closer examination of the ring deposits reveals that several layers of silica rods close to the edge of the drop are ordered such that the major axis of the rods are oriented parallel to the contact line. After the first few layers of ordered arrangement of particles, a random arrangement of particles in the drop interior is observed indicating an order-disorder transition in the ring. We monitor the evolution of the ring width and particle velocity during evaporation to elucidate the mechanism of the order-disorder transition. Moreover, when the evaporation rate is lowered, the ordering of silica rods is observed to extend over large areas. We demonstrate that the nature of the deposit can be tuned by the addition of a small quantity of surfactant or salt. PMID:25521279

  11. Slide Rule For Calculating Curing Schedules

    NASA Technical Reports Server (NTRS)

    Heater, Don

    1995-01-01

    Special-purpose slide rule devised for calculating schedules for storing and curing adhesives, sealants, and other materials characterized by known curing times and shelf lives. Prevents mistakes commonly made in determining storage and curing schedules.

  12. Water Slides: Look Before You Leap.

    ERIC Educational Resources Information Center

    Barks, Dan

    1986-01-01

    The Campbell County Parks and Recreation Department discovered that higher costs, more details, insurance difficulties, and longer construction periods were the rule when a water slide was planned and constructed. The project is described. (MT)

  13. 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.

  14. 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.

  15. Stereoscopic Projection of 35mm Slides.

    ERIC Educational Resources Information Center

    Carey, Edward F.

    1978-01-01

    Describes ways of projecting stereoscopic images of geologic environments for students with difficulty reasoning in three-dimensions. The photographic procedures needed to produce stereo slides are included. (MA)

  16. Spooled packaging of shape memory alloy actuators

    NASA Astrophysics Data System (ADS)

    Redmond, John A.

    A vast cross-section of transportation, manufacturing, consumer product, and medical technologies rely heavily on actuation. Accordingly, progress in these industries is often strongly coupled to the advancement of actuation technologies. As the field of actuation continues to evolve, smart materials show significant promise for satisfying the growing needs of industry. In particular, shape memory alloy (SMA) wire actuators present an opportunity for low-cost, high performance actuation, but until now, they have been limited or restricted from use in many otherwise suitable applications by the difficulty in packaging the SMA wires within tight or unusually shaped form constraints. To address this packaging problem, SMA wires can be spool-packaged by wrapping around mandrels to make the actuator more compact or by redirecting around multiple mandrels to customize SMA wire pathways to unusual form factors. The goal of this dissertation is to develop the scientific knowledge base for spooled packaging of low-cost SMA wire actuators that enables high, predictable performance within compact, customizable form factors. In developing the scientific knowledge base, this dissertation defines a systematic general representation of single and multiple mandrel spool-packaged SMA actuators and provides tools for their analysis, understanding, and synthesis. A quasi-static analytical model distills the underlying mechanics down to the three effects of friction, bending, and binding, which enables prediction of the behavior of generic spool-packaged SMA actuators with specifiable geometric, loading, frictional, and SMA material parameters. An extensive experimental and simulation-based parameter study establishes the necessary understanding of how primary design tradeoffs between performance, packaging, and cost are governed by the underlying mechanics of spooled actuators. A design methodology outlines a systematic approach to synthesizing high performance SMA wire actuators

  17. Lost-motion valve actuator

    SciTech Connect

    Burris, W.J. III; Ringgenberg, P.D.

    1987-04-07

    A lost-motion valve actuator is described for a bore closure valve employed in a well bore, comprising: operating connector means adapted to move the bore closure valve between open and closed positions through longitudinal movement of the operating connector means. The operating connector means comprises an operating connector and a connector insert defining a recess therebetween; locking dog means comprising at least one locking dog received in the recess and spring biasing means adapted to urge at least one locking dog radially inwardly; and mandrel means slidably received within the operating connector means and including dog slot means associated therewith. The dog slot means comprises an annular slot on the exterior of the mandrel means adapted to lockingly receive at least one inwardly biased locking dog when proximate thereto, whereby longitudinal movement of the mandrel means is transmitted to the operating connector means.

  18. Magnetic actuation of hair cells

    PubMed Central

    Rowland, David; Roongthumskul, Yuttana; Lee, Jae-Hyun; Cheon, Jinwoo; Bozovic, Dolores

    2011-01-01

    The bullfrog sacculus contains mechanically sensitive hair cells whose stereociliary bundles oscillate spontaneously when decoupled from the overlying membrane. Steady-state offsets on the resting position of a hair bundle can suppress or modulate this native motility. To probe the dynamics of spontaneous oscillation in the proximity of the critical point, we describe here a method for mechanical actuation that avoids loading the bundles or contributing to the viscous drag. Magnetite beads were attached to the tips of the stereocilia, and a magnetic probe was used to impose deflections. This technique allowed us to observe the transition from multi-mode to single-mode state in freely oscillating bundles, as well as the crossover from the oscillatory to the quiescent state. PMID:22163368

  19. Magnetic actuation of hair cells.

    PubMed

    Rowland, David; Roongthumskul, Yuttana; Lee, Jae-Hyun; Cheon, Jinwoo; Bozovic, Dolores

    2011-11-01

    The bullfrog sacculus contains mechanically sensitive hair cells whose stereociliary bundles oscillate spontaneously when decoupled from the overlying membrane. Steady-state offsets on the resting position of a hair bundle can suppress or modulate this native motility. To probe the dynamics of spontaneous oscillation in the proximity of the critical point, we describe here a method for mechanical actuation that avoids loading the bundles or contributing to the viscous drag. Magnetite beads were attached to the tips of the stereocilia, and a magnetic probe was used to impose deflections. This technique allowed us to observe the transition from multi-mode to single-mode state in freely oscillating bundles, as well as the crossover from the oscillatory to the quiescent state. PMID:22163368

  20. Droplet actuator analyzer with cartridge

    NASA Technical Reports Server (NTRS)

    Smith, Gregory F. (Inventor); Sturmer, Ryan A. (Inventor); Paik, Philip Y. (Inventor); Srinivasan, Vijay (Inventor); Pollack, Michael G. (Inventor); Pamula, Vamsee K. (Inventor); Brafford, Keith R. (Inventor); West, Richard M. (Inventor)

    2011-01-01

    A droplet actuator with cartridge is provided. According to one embodiment, a sample analyzer is provided and includes an analyzer unit comprising electronic or optical receiving means, a cartridge comprising self-contained droplet handling capabilities, and a wherein the cartridge is coupled to the analyzer unit by a means which aligns electronic and/or optical outputs from the cartridge with electronic or optical receiving means on the analyzer unit. According to another embodiment, a sample analyzer is provided and includes a sample analyzer comprising a cartridge coupled thereto and a means of electrical interface and/or optical interface between the cartridge and the analyzer, whereby electrical signals and/or optical signals may be transmitted from the cartridge to the analyzer.

  1. Pressure-actuated joint system

    NASA Technical Reports Server (NTRS)

    McGuire, John R. (Inventor)

    2004-01-01

    A pressure vessel is provided that includes first and second case segments mated with one another. First and second annular rubber layers are disposed inboard of the first and second case segments, respectively. The second annular rubber layer has a slot extending from the radial inner surface across a portion of its thickness to define a main body portion and a flexible portion. The flexible portion has an interfacing surface portion abutting against an interfacing surface portion of the first annular rubber layer to follow movement of the first annular rubber layer during operation of the pressure vessel. The slot receives pressurized gas and establishes a pressure-actuated joint between the interfacing surface portions. At least one of the interfacing surface portions has a plurality of enclosed and sealed recesses formed therein.

  2. 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.

  3. Compensator-based 6-DOF control for probe asteroid-orbital-frame hovering with actuator limitations

    NASA Astrophysics Data System (ADS)

    Liu, Xiaosong; Zhang, Peng; Liu, Keping; Li, Yuanchun

    2016-05-01

    This paper is concerned with 6-DOF control of a probe hovering in the orbital frame of an asteroid. Considering the requirements of the scientific instruments pointing direction and orbital position in practical missions, the coordinate control of relative attitude and orbit between the probe and target asteroid is imperative. A 6-DOF dynamic equation describing the relative translational and rotational motion of a probe in the asteroid's orbital frame is derived, taking the irregular gravitation, model and parameter uncertainties and external disturbances into account. An adaptive sliding mode controller is employed to guarantee the convergence of the state error, where the adaptation law is used to estimate the unknown upper bound of system uncertainty. Then the controller is improved to deal with the practical problem of actuator limitations by introducing a RBF neural network compensator, which is used to approximate the difference between the actual control with magnitude constraint and the designed nominal control law. The closed-loop system is proved to be asymptotically stable through the Lyapunov stability analysis. Numerical simulations are performed to compare the performances of the preceding designed control laws. Simulation results demonstrate the validity of the control scheme using the compensator-based adaptive sliding mode control law in the presence of actuator limitations, system uncertainty and external disturbance.

  4. 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…

  5. 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…

  6. Connexin 36 and rod bipolar cell independent rod pathways drive retinal ganglion cells and optokinetic reflexes.

    PubMed

    Cowan, Cameron S; Abd-El-Barr, Muhammad; van der Heijden, Meike; Lo, Eric M; Paul, David; Bramblett, Debra E; Lem, Janis; Simons, David L; Wu, Samuel M

    2016-02-01

    Rod pathways are a parallel set of synaptic connections which enable night vision by relaying and processing rod photoreceptor light responses. We use dim light stimuli to isolate rod pathway contributions to downstream light responses then characterize these contributions in knockout mice lacking rod transducin-α (Trα), or certain pathway components associated with subsets of rod pathways. These comparisons reveal that rod pathway driven light sensitivity in retinal ganglion cells (RGCs) is entirely dependent on Trα, but partially independent of connexin 36 (Cx36) and rod bipolar cells. Pharmacological experiments show that rod pathway-driven and Cx36-independent RGC ON responses are also metabotropic glutamate receptor 6-dependent. To validate the RGC findings in awake, behaving animals we measured optokinetic reflexes (OKRs), which are sensitive to changes in ON pathways. Scotopic OKR contrast sensitivity was lost in Trα(-/-) mice, but indistinguishable from controls in Cx36(-/-) and rod bipolar cell knockout mice. Mesopic OKRs were also altered in mutant mice: Trα(-/-) mice had decreased spatial acuity, rod BC knockouts had decreased sensitivity, and Cx36(-/-) mice had increased sensitivity. These results provide compelling evidence against the complete Cx36 or rod BC dependence of night vision's ON component. Further, the findings suggest the parallel nature of rod pathways provides considerable redundancy to scotopic light sensitivity but distinct contributions to mesopic responses through complicated interactions with cone pathways. PMID:26718442

  7. Preparing Scientific Papers, Posters, and Slides.

    PubMed

    Lefor, Alan Kawarai; Maeno, Misato

    2016-01-01

    Publications and presentations are important in academic medicine. The ability to present information in a standard fashion is critically important. Papers, posters, and slides must be prepared appropriately to maximize their chance of being accepted. The first step is to use word processing software correctly. English language usage must conform to standard scientific English usage. Abbreviations should be avoided as much as possible. Numerical data must be presented with the appropriate number of significant figures. The first step in preparing a paper is to decide the target journal. Papers should always be written in 12 point Times New Roman font, while slides and posters should be in Arial or Helvetica. The Results section must contain actual data with appropriate statistical analysis. Take great care to prepare figures and tables according to the journal's instructions. Posters must be prepared to allow easy reading at a distance of 2m. Use a white background and dark letters. The majority of the area of your poster should be Results, and there is no need to include the abstract or references on a poster. Slide presentations should be limited to about one slide for each minute of the talk. Avoid the use of animations and excessive use of color. Do not use abbreviations on slides. Following these simple guidelines will meet the requirements of most journals and allow your audience to appreciate the data on your posters and slides. PMID:26572095

  8. Speckle tracking technology for quantifying lung sliding.

    PubMed

    Dori, Guy; Jakobson, Daniel J

    2016-06-01

    Ultrasound (US) is gaining recognition as a useful tool for assessing lung physiology and pathology. Yet, currently the skill of performing lung US is taught by experienced operators to novice ones, mainly by recognizing expected patterns. Recognizing the latter may be difficult and subjective. In this hypothesis we propose to apply a well-known and used image processing technology in echocardiography, speckle tracking (ST), to lung sliding - the marker of normal lung function. If implementing ST to lung sliding is technically feasible, several outcomes are expected: (1) Lung sliding will become an objective, operator-independent marker of normal lung function. (2) Subsequently, ST will provide normal values for lung sliding. (3) Lastly, the effects of pulmonary pathologies on lung sliding may be assessed. It is stressed, however, that the preliminary idea suggested here is limited to a single physiological phenomenon (lung sliding). Only when technical feasibility is demonstrated then ST technology may potentially be applied and investigated in other clinical settings of lung diseases. PMID:27142150

  9. Out-of-Plane Translational PZT Bimorph Actuator with Archimedes’ Spiral Actuating Tethers

    NASA Astrophysics Data System (ADS)

    Yang, Chenye; Liu, Sanwei; Livermore, Carol

    2015-12-01

    The design, finite element analysis (FEA), and experimental characterization of a MEMS out-of-plane (vertical) translational lead-zirconate-titanate (PZT) bimorph actuator supported on Archimedes’ spiral tethers are presented. Two types of bimorph actuators with different electrode patterns (with spiral tethers half actuated or fully actuated) are designed and fabricated. Both designs are fabricated by commercial processes and are compatible with integration into more complex MEMS systems. Finite element analysis (FEA) was used to analyze and predict the displacements of both types of actuators. The deflections of both fully- actuated and half-actuated devices were measured experimentally to validate the design. At an applied voltage of 110V, the out-of-plane deflections of the actuators with half-actuated and fully-actuated tethers were measured at about 17 μm and 29 μm respectively, in good agreement with FEA predictions of 17.1 μm and 25.8 μm. The corresponding blocking forces are predicted as 10 mN and 17 mN by FEA.

  10. Enhanced Actuation Performance and Reduced Heat Generation in Shear-Bending Mode Actuator at High Temperature.

    PubMed

    Chen, Jianguo; Liu, Guoxi; Cheng, Jinrong; Dong, Shuxiang

    2016-08-01

    The actuation performance, strain hysteresis, and heat generation of the shear-bending mode actuators based on soft and hard BiScO3-PbTiO3 (BS-PT) ceramics were investigated under different thermal (from room temperature to 300 °C) and electrical loadings (from 2 to 10 kV/cm and from 1 to 1000 Hz). The actuator based on both soft and hard BS-PT ceramics worked stably at the temperature as high as 300 °C. The maximum working temperature of this shear-bending actuators is 150 °C higher than those of the traditional piezoelectric actuators based on commercial Pb(Zr, Ti)O3 materials. Furthermore, although the piezoelectric properties of soft-type ceramics based on BS-PT ceramics were superior to those of hard ceramics, the maximum displacement of the actuator based on hard ceramics was larger than that fabricated by soft ceramics at high temperature. The maximum displacement of the actuator based on hard ceramics was [Formula: see text] under an applied electric field of 10 kV/cm at 300 °C. The strain hysteresis and heat generation of the actuator based on hard ceramics was smaller than those of the actuator based on soft ceramics in the wide temperature range. These results indicated that the shear-bending actuator based on hard piezoelectric ceramics was more suitable for high-temperature piezoelectric applications. PMID:27214895

  11. Flight Control Design for an Autonomous Rotorcraft Using Pseudo-Sliding Mode Control and Waypoint Navigation

    NASA Astrophysics Data System (ADS)

    Mallory, Nicolas Joseph

    The design of robust automated flight control systems for aircraft of varying size and complexity is a topic of continuing interest for both military and civilian industries. By merging the benefits of robustness from sliding mode control (SMC) with the familiarity and transparency of design tradeoff offered by frequency domain approaches, this thesis presents pseudo-sliding mode control as a viable option for designing automated flight control systems for complex six degree-of-freedom aircraft. The infinite frequency control switching of SMC is replaced, by necessity, with control inputs that are continuous in nature. An introduction to SMC theory is presented, followed by a detailed design of a pseudo-sliding mode control and automated flight control system for a six degree-of-freedom model of a Hughes OH6 helicopter. This model is then controlled through three different waypoint missions that demonstrate the stability of the system and the aircraft's ability to follow certain maneuvers despite time delays, large changes in model parameters and vehicle dynamics, actuator dynamics, sensor noise, and atmospheric disturbances.

  12. Bi-directional series-parallel elastic actuator and overlap of the actuation layers.

    PubMed

    Furnémont, Raphaël; Mathijssen, Glenn; Verstraten, Tom; Lefeber, Dirk; Vanderborght, Bram

    2016-02-01

    Several robotics applications require high torque-to-weight ratio and energy efficient actuators. Progress in that direction was made by introducing compliant elements into the actuation. A large variety of actuators were developed such as series elastic actuators (SEAs), variable stiffness actuators and parallel elastic actuators (PEAs). SEAs can reduce the peak power while PEAs can reduce the torque requirement on the motor. Nonetheless, these actuators still cannot meet performances close to humans. To combine both advantages, the series parallel elastic actuator (SPEA) was developed. The principle is inspired from biological muscles. Muscles are composed of motor units, placed in parallel, which are variably recruited as the required effort increases. This biological principle is exploited in the SPEA, where springs (layers), placed in parallel, can be recruited one by one. This recruitment is performed by an intermittent mechanism. This paper presents the development of a SPEA using the MACCEPA principle with a self-closing mechanism. This actuator can deliver a bi-directional output torque, variable stiffness and reduced friction. The load on the motor can also be reduced, leading to a lower power consumption. The variable recruitment of the parallel springs can also be tuned in order to further decrease the consumption of the actuator for a given task. First, an explanation of the concept and a brief description of the prior work done will be given. Next, the design and the model of one of the layers will be presented. The working principle of the full actuator will then be given. At the end of this paper, experiments showing the electric consumption of the actuator will display the advantage of the SPEA over an equivalent stiff actuator. PMID:26813145

  13. Magnetic suspension characteristics of electromagnetic actuators

    NASA Technical Reports Server (NTRS)

    Rao, Dantam K.; Dill, J.; Zorzi, E.

    1993-01-01

    Electromagnetic actuators that use a current-carrying coil (which is placed in a magnetic field) to generate mechanical force are conceptually attractive components for active control of rotating shafts. In one concept that is being tested in the laboratory, the control forces from such actuators are applied on the flexibly supported bearing housings of the rotor. Development of this concept into a practical reality requires a clear and thorough understanding of the role of electromechanical parameters of these actuators in delivering the right amount of control force at the right phase into the rotor. The electromechanical parameters of the actuators investigated are the mass of the armature, stiffness of its suspension, electrical resistance, and inductance of the coils. Improper selection of these parameters can result in degradation in their performance, leading to mistuning between the actuator and the rotor. Through a simple analysis, it is shown that use of such mistuned actuators could result in sharp fluctuations in the phase of the control force delivered into the rotor around the critical speeds. These sharp fluctuations in phase, called 'Phase Glitches', are undesirable. Hence, future designs of controllers should take into account the undesirable mistuning effects between the actuator and the rotor caused by the phase glitches.

  14. Dielectric elastomer actuators with hydrostatic coupling

    NASA Astrophysics Data System (ADS)

    Carpi, Federico; Frediani, Gabriele; De Rossi, Danilo

    2009-03-01

    The rapidly growing adoption of dielectric elastomer (DE) actuators as a high performance EAP technology for many kinds of new applications continuously opens new technical challenges, in order to take always the most from each adopted device and actuating configuration. This paper presents a new type of DE actuators, which show attractive potentialities for specific application needs. The concept here proposed adopts an incompressible fluid to mechanically couple active and passive parts. The active parts work according to the DE actuation principle, while the passive parts represent the end effector, in contact with the load. The fluid is used to transfer actuation hydrostatically from an active to a passive part and, then, to the load. This can provide specific advantages, including improved safety and less stringent design constraints for the architecture of the actuator, especially for soft end effectors. Such a simple concept can be readily implemented according to different shapes and intended functionalities of the resulting actuators. The paper describes the structure and the performance of the first prototype devices developed so far.

  15. Active Damping Using Distributed Anisotropic Actuators

    NASA Technical Reports Server (NTRS)

    Schiller, Noah H.; Cabell, Randolph H.; Quinones, Juan D.; Wier, Nathan C.

    2010-01-01

    A helicopter structure experiences substantial high-frequency mechanical excitation from powertrain components such as gearboxes and drive shafts. The resulting structure-borne vibration excites the windows which then radiate sound into the passenger cabin. In many cases the radiated sound power can be reduced by adding damping. This can be accomplished using passive or active approaches. Passive treatments such as constrained layer damping tend to reduce window transparency. Therefore this paper focuses on an active approach utilizing compact decentralized control units distributed around the perimeter of the window. Each control unit consists of a triangularly shaped piezoelectric actuator, a miniature accelerometer, and analog electronics. Earlier work has shown that this type of system can increase damping up to approximately 1 kHz. However at higher frequencies the mismatch between the distributed actuator and the point sensor caused control spillover. This paper describes new anisotropic actuators that can be used to improve the bandwidth of the control system. The anisotropic actuators are composed of piezoelectric material sandwiched between interdigitated electrodes, which enables the application of the electric field in a preferred in-plane direction. When shaped correctly the anisotropic actuators outperform traditional isotropic actuators by reducing the mismatch between the distributed actuator and point sensor at high frequencies. Testing performed on a Plexiglas panel, representative of a helicopter window, shows that the control units can increase damping at low frequencies. However high frequency performance was still limited due to the flexible boundary conditions present on the test structure.

  16. Characterization of piezoelectric macrofiber composite actuated winglets

    NASA Astrophysics Data System (ADS)

    Guha, T. K.; Oates, W. S.; Kumar, R.

    2015-06-01

    The present study primarily focuses on the design, development, and structural characterization of an oscillating winglet actuated using a piezoelectric macrofiber composite (MFC). The primary objective is to study the effect of controlled wingtip oscillations on the evolution of wingtip vortices, with a goal of weakening these potentially harmful tip vortices by introducing controlled instabilities through both spatial and temporal perturbations producible through winglet oscillations. MFC-actuated winglets have been characterized under different input excitation and pressure-loading conditions. The winglet oscillations show bimodal behavior for both structural and actuation modes of resonance. The oscillatory amplitude at these actuation modes increases linearly with the magnitude of excitation. During wind-tunnel tests, fluid-structure interactions led to structural vibrations of the wing. The effect of these vibrations on the overall winglet oscillations decreased when the strength of actuation increased. At high input excitation, the actuated winglet was capable of generating controlled oscillations. As a proof of concept, the current study has demonstrated that microfiber composite-actuated winglets produce sufficient displacements to alter the development of the wingtip vortex.

  17. V2O5 nanofibre sheet actuators

    NASA Astrophysics Data System (ADS)

    Gu, Gang; Schmid, Michael; Chiu, Po-Wen; Minett, Andrew; Fraysse, Jerôme; Kim, Gyu-Tae; Roth, Siegmar; Kozlov, Mikhail; Muñoz, Edgar; Baughman, Ray H.

    2003-05-01

    Vanadium oxides, such as V2O5, are promising for lithium-ion batteries, catalysis, electrochromic devices and sensors. Vanadium oxides were proposed more than a decade ago for another redox-dependent application: the direct conversion of electrical energy to mechanical energy in actuators (artificial muscles). Although related conducting polymer and carbon nanotube actuators have been demonstrated, electromechanical actuators based on vanadium oxides have not be realized. V2O5 nanofibres and nanotubes provide the potential advantages of low-cost synthesis by sol-gel routes and high charging capacity and long cycle life. Here, we demonstrate electromechanical actuation for obtained high modulus V2O5 sheets comprising entangled V2O5 nanofibres. The high surface area of these V2O5 sheets facilitates electrochemical charge injection and intercalation that causes the electromechanical actuation. We show that the V2O5 sheets provide high Young's modulus, high actuator-generated stress, and high actuator stroke at low applied voltage.

  18. Advanced piezoelectric single crystal based actuators

    NASA Astrophysics Data System (ADS)

    Jiang, Xiaoning; Rehrig, Paul W.; Hackenberger, Wesley S.; Smith, Edward; Dong, Shuxiang; Viehland, Dwight; Moore, Jim, Jr.; Patrick, Brian

    2005-05-01

    TRS is developing new actuators based on single crystal piezoelectric materials such as Pb(Zn1/3Nb2/3)1-xTixO3 (PZN-PT) and Pb(Mg1/3Nb2/3)x-1TixO3 (PMN-PT) which exhibit very high piezoelectric coefficients (d33 = 1800-2200 pC/N) and electromechanical coupling factors (k33 > 0.9), respectively, for a variety of applications, including active vibration damping, active flow control, high precision positioning, ultrasonic motors, deformable mirrors, and adaptive optics. The d32 cut crystal plate actuators showed d32 ~ -1600 pC/N, inter-digital electroded (IDE) plate actuators showed effective d33 ~ 1100 pC/N. Single crystal stack actuators with stroke of 10 μm-100 μm were developed and tested at both room temperature and cryogenic temperatures. Flextensional single crystal piezoelectric actuators with either stack driver or plate driver were developed with stroke 70 μm - > 250 μm. For large stroke cryogenic actuation (> 1mm), a single crystal piezomotor was developed and tested at temperature of 77 K-300K and stroke of > 10mm and step resolution of 20 nm were achieved. In order to demonstrate the significance of developed single crystal actuators, modeling on single crystal piezoelectric deformable mirrors and helicopter flap control using single crystal actuators were conducted and the modeling results show that more than 20 wavelength wavefront error could be corrected by using the single crystal deformable mirrors and +/- 5.8 ° flap deflection will be obtained for a 36" flap using single crystal stack actuators.

  19. Actuator Exerts Tensile Or Compressive Axial Load

    NASA Technical Reports Server (NTRS)

    Nozzi, John; Richards, Cuyler H.

    1994-01-01

    Compact, manually operated mechanical actuator applies controlled, limited tensile or compressive axial force. Designed to apply loads to bearings during wear tests in clean room. Intended to replace hydraulic actuator. Actuator rests on stand and imparts axial force to part attached to clevis inside or below stand. Technician turns control screw at one end of lever. Depending on direction of rotation of control screw, its end of lever driven downward (for compression) or upward (for tension). Lever pivots about clevis pin at end opposite of control screw; motion drives downward or upward link attached via shearpin at middle of lever. Link drives coupling and, through it, clevis attached to part loaded.

  20. Membrane Mirrors With Bimorph Shape Actuators

    NASA Technical Reports Server (NTRS)

    Yang, Eui-Hyeok

    2003-01-01

    Deformable mirrors of a proposed type would be equipped with relatively-large-stroke microscopic piezoelectric actuators that would be used to maintain their reflective surfaces in precise shapes. These mirrors would be members of the class of MEMS-DM (for microelectromechanical system deformable mirror) devices, which offer potential for a precise optical control in adaptive-optics applications in such diverse fields as astronomy and vision science. The proposed mirror would be fabricated, in part, by use of a membrane-transfer technique. The actuator design would contain bimorph-type piezoelectric actuators.

  1. Diagnostics for characterisation of plasma actuators

    NASA Astrophysics Data System (ADS)

    Kotsonis, Marios

    2015-09-01

    The popularity of plasma actuators as flow control devices has sparked a flurry of diagnostic efforts towards their characterisation. This review article presents an overview of experimental investigations employing diagnostic techniques specifically aimed at AC dielectric barrier discharge, DC corona and nanosecond pulse plasma actuators. Mechanical, thermal and electrical characterisation techniques are treated. Various techniques for the measurement of induced velocity, body force, heating effects, voltage, current, power and discharge morphology are presented and common issues and challenges are described. The final part of this report addresses the effect of ambient conditions on the performance of plasma actuators.

  2. Optimization Strategies for Sensor and Actuator Placement

    NASA Technical Reports Server (NTRS)

    Padula, Sharon L.; Kincaid, Rex K.

    1999-01-01

    This paper provides a survey of actuator and sensor placement problems from a wide range of engineering disciplines and a variety of applications. Combinatorial optimization methods are recommended as a means for identifying sets of actuators and sensors that maximize performance. Several sample applications from NASA Langley Research Center, such as active structural acoustic control, are covered in detail. Laboratory and flight tests of these applications indicate that actuator and sensor placement methods are effective and important. Lessons learned in solving these optimization problems can guide future research.

  3. Microcantilever actuation via periodic internal heating

    SciTech Connect

    Lee, Jungchul; King, William P.

    2007-12-15

    This paper reports electrothermal actuation of silicon microcantilevers having integrated resistive heaters. Periodic electrical excitation induced periodic resistive heating in the cantilever, while the cantilever deflection was monitored with a photodetector. Excitation was either at the cantilever resonant frequency, f{sub 0}, f{sub 0}/2, or f{sub 0}/3. When the time averaged maximum cantilever temperature was 174 deg. C, the cantilever out-of-plane actuation amplitude was 484 nm near the cantilever resonance frequency of 24.9 kHz. This actuation was sufficiently large to operate the cantilever in intermittent contact mode and scan a calibration grating of height of 20 nm.

  4. Refreshable Braille Displays Using EAP Actuators

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph

    2010-01-01

    Refreshable Braille can help visually impaired persons benefit from the growing advances in computer technology. The development of such displays in a full screen form is a great challenge due to the need to pack many actuators in small area without interferences. In recent years, various displays using actuators such as piezoelectric stacks have become available in commercial form but most of them are limited to one line Braille code. Researchers in the field of electroactive polymers (EAP) investigated methods of using these materials to form full screen displays. This manuscript reviews the state of the art of producing refreshable Braille displays using EAP-based actuators..

  5. Misfire tolerant combustion-powered actuation

    DOEpatents

    Spletzer, Barry L.; Fischer, Gary J.; Marron, Lisa C.; Kuehl, Michael A.

    2001-01-01

    The present invention provides a combustion-powered actuator that is suitable for intermittent actuation, that is suitable for use with atmospheric pressure carburetion, and that requires little electrical energy input. The present invention uses energy from expansion of pressurized fuel to effectively purge a combustion chamber, and to achieve atmospheric pressure carburetion. Each purge-fill-power cycle can be independent, allowing the actuator to readily tolerate misfires. The present invention is suitable for use with linear and rotary operation combustion chambers, and is suitable for use in a wide variety of applications.

  6. A Model of the THUNDER Actuator

    NASA Technical Reports Server (NTRS)

    Curtis, Alan R. D.

    1997-01-01

    A THUNDER actuator is a composite of three thin layers, a metal base, a piezoelectric wafer and a metal top cover, bonded together under pressure and at high temperature with the LaRC SI polyimid adhesive. When a voltage is applied between the metal layers across the PZT the actuator will bend and can generate a force. This document develops and describes an analytical model the transduction properties of THUNDER actuators. The model development is divided into three sections. First, a static model is described that relates internal stresses and strains and external displacements to the thermal pre-stress and applied voltage. Second, a dynamic energy based model is described that allows calculation of the resonance frequencies, developed force and electrical input impedance. Finally, a fully coupled electro-mechanical transducer model is described. The model development proceeds by assuming that both the thermal pre-stress and the piezoelectric actuation cause the actuator to deform in a pure bend in a single plane. It is useful to think of this as a two step process, the actuator is held flat, differential stresses induce a bending moment, the actuator is released and it bends. The thermal pre-stress is caused by the different amounts that the constituent layers shrink due to their different coefficients of thermal expansion. The adhesive between layers sets at a high temperature and as the actuator cools, the metal layers shrink more than the PZT. The PZT layer is put into compression while the metal layers are in tension. The piezoelectric actuation has a similar effect. An applied voltage causes the PZT layer to strain, which in turn strains the two metal layers. If the PZT layer expands it will put the metal layers into tension and PZT layer into compression. In both cases, if shear force effects are neglected, the actuator assembly will experience a uniform in-plane strain. As the materials each have a different elastic modulus, different stresses will

  7. Peristaltic pump made of dielectric elastomer actuators

    NASA Astrophysics Data System (ADS)

    Lotz, Peter; Matysek, Marc; Schlaak, Helmut F.

    2009-03-01

    The functional principle of peristaltic motion is inspired by the pattern in which hollow organs move. The technology of dielectric elastomer actuators provides the possibility to design a very compact peristaltic pump. The geometries of the whole pump and the actuator elements have been determined by numerical simulations of the mechanical behaviour and the fluid dynamics. With eight independent actuators the pumping channel is self-sealing and there is no need for any valves. The first generation of this pump is able to generate flow rates up to 0.36 μl/min.

  8. Bluff Body Flow Control Using Plasma Actuators

    NASA Astrophysics Data System (ADS)

    Thomas, Flint

    2005-11-01

    In this study, the use of single dielectric barrier discharge plasma actuators for the control of bluff body flow separation is investigated. In particular, surface mounted plasma actuators are used to reduce both drag and unsteady vortex shedding from circular cylinders in cross-flow. It is demonstrated that the plasma-induced surface blowing gives rise to a local Coanda effect that promotes the maintenance of flow attachment. Large reductions in vortex shedding and drag are demonstrated for Reynolds numbers ˜ 10^410^5. Both steady and unsteady plasma-induced surface blowing is explored. Results are presented from experiments involving both two and four surface mounted actuators.

  9. Recent Developments in NASA Piezocomposite Actuator Technology

    NASA Technical Reports Server (NTRS)

    Wilkie, William K.; Inman, Daniel J.; High, James W.; Williams, R. Brett

    2004-01-01

    In this paper, we present an overview of recent progress in the development of the NASA Macro-Fiber Composite (MFC) piezocomposite actuator device. This will include a brief history of the development of the MFC, a description of the standard manufacturing process used to fabricate MFC actuators, and a summary of ongoing MFC electromechanical characterization testing. In addition, we describe the development of a prototype single-crystal piezoelectric MFC device, and compare its performance with MFC actuator specimens utilizing conventional piezoceramic materials.

  10. Hydraulic Actuator System for Rotor Control

    NASA Technical Reports Server (NTRS)

    Ulbrich, Heinz; Althaus, Josef

    1991-01-01

    In the last ten years, several different types of actuators were developed and fabricated for active control of rotors. A special hydraulic actuator system capable of generating high forces to rotating shafts via conventional bearings is addressed. The actively controlled hydraulic force actuator features an electrohydraulic servo valve which can produce amplitudes and forces at high frequencies necessary for influencing rotor vibrations. The mathematical description will be given in detail. The experimental results verify the theoretical model. Simulations already indicate the usefulness of this compact device for application to a real rotor system.

  11. Semantic Focusing Allows Fully Automated Single-Layer Slide Scanning of Cervical Cytology Slides

    PubMed Central

    Lahrmann, Bernd; Valous, Nektarios A.; Eisenmann, Urs; Wentzensen, Nicolas; Grabe, Niels

    2013-01-01

    Liquid-based cytology (LBC) in conjunction with Whole-Slide Imaging (WSI) enables the objective and sensitive and quantitative evaluation of biomarkers in cytology. However, the complex three-dimensional distribution of cells on LBC slides requires manual focusing, long scanning-times, and multi-layer scanning. Here, we present a solution that overcomes these limitations in two steps: first, we make sure that focus points are only set on cells. Secondly, we check the total slide focus quality. From a first analysis we detected that superficial dust can be separated from the cell layer (thin layer of cells on the glass slide) itself. Then we analyzed 2,295 individual focus points from 51 LBC slides stained for p16 and Ki67. Using the number of edges in a focus point image, specific color values and size-inclusion filters, focus points detecting cells could be distinguished from focus points on artifacts (accuracy 98.6%). Sharpness as total focus quality of a virtual LBC slide is computed from 5 sharpness features. We trained a multi-parameter SVM classifier on 1,600 images. On an independent validation set of 3,232 cell images we achieved an accuracy of 94.8% for classifying images as focused. Our results show that single-layer scanning of LBC slides is possible and how it can be achieved. We assembled focus point analysis and sharpness classification into a fully automatic, iterative workflow, free of user intervention, which performs repetitive slide scanning as necessary. On 400 LBC slides we achieved a scanning-time of 13.9±10.1 min with 29.1±15.5 focus points. In summary, the integration of semantic focus information into whole-slide imaging allows automatic high-quality imaging of LBC slides and subsequent biomarker analysis. PMID:23585899

  12. Sahara Slide: Age, initiation, and processes of a giant submarine slide

    NASA Astrophysics Data System (ADS)

    Georgiopoulou, Aggeliki; Masson, Douglas G.; Wynn, Russell B.; Krastel, Sebastian

    2010-07-01

    The Sahara Slide is a giant submarine landslide on the northwest African continental margin. The landslide is located on the open continental slope offshore arid Western Sahara, with a headwall at a water depth of ˜2000 m. High primary productivity in surface waters drives accumulation of thick fine-grained pelagic/hemipelagic sediment sequences in the slide source area. Rare but large-scale slope failures, such as the Sahara Slide that remobilized approximately 600 km3 of sediment, are characteristic of this sedimentological setting. Seismic profiles collected from the slide scar reveal a stepped profile with two 100 m high headwalls, suggesting that the slide occurred retrogressively as a slab-type failure. Sediment cores recovered from the slide deposit provide new insights into the process by which the slide eroded and entrained a volcaniclastic sand layer. When this layer was entrained at the base of the slide it became fluidized and resulted in low apparent friction, facilitating the exceptionally long runout of ˜900 km. The slide location appears to be controlled by the buried headwall of an older slope failure, and we suggest that the cause of the slide relates to differential sedimentation rates and compaction across these scarps, leading to local increases of pore pressure. Sediment cores yield a date of 50-60 ka for the main slide event, a period of global sea level rise which may have contributed to pore pressure buildup. The link with sea level rising is consistent with other submarine landslides on this margin, drawing attention to this potential hazard during global warming.

  13. Computing Temperatures In Optically Pumped Laser Rods

    NASA Technical Reports Server (NTRS)

    Farrukh, Usamah O.

    1991-01-01

    Computer program presents new model solving temperature-distribution problem for laser rods of finite length and calculates both radial and axial components of temperature distributions in these rods. Contains several self-checking schemes to prevent over-writing of memory blocks and to provide simple tracing of information in case of trouble. Written in Microsoft FORTRAN 77.

  14. Tipping Time of a Quantum Rod

    ERIC Educational Resources Information Center

    Parrikar, Onkar

    2010-01-01

    The behaviour of a quantum rod, pivoted at its lower end on an impenetrable floor and restricted to moving in the vertical plane under the gravitational potential, is studied analytically under the approximation that the rod is initially localized to a "small-enough" neighbourhood around the point of classical unstable equilibrium. It is shown…

  15. Choosing Actuators for Automatic Control Systems of Thermal Power Plants

    SciTech Connect

    Gorbunov, A. I.; Serdyukov, O. V.

    2015-03-15

    Two types of actuators for automatic control systems of thermal power plants are analyzed: (i) pulse-controlled actuator and (ii) analog-controlled actuator with positioning function. The actuators are compared in terms of control circuit, control accuracy, reliability, and cost.

  16. Vortex Noise from Rotating Cylindrical Rods

    NASA Technical Reports Server (NTRS)

    Stowell, E Z; Deming, A F

    1935-01-01

    A series of round rods of the some diameter were rotated individually about the mid-point of each rod. Vortices are shed from the rods when in motion, giving rise to the emission of sound. With the rotating system placed in the open air, the distribution of sound in space, the acoustical power output, and the spectral distribution have been studied. The frequency of emission of vortices from any point on the rod is given by the formula von Karman. From the spectrum estimates are made of the distribution of acoustical power along the rod, the amount of air concerned in sound production, the "equivalent size" of the vortices, and the acoustical energy content for each vortex.

  17. Rod-Coil Block Polyimide Copolymers

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B. (Inventor); Kinder, James D. (Inventor)

    2005-01-01

    This invention is a series of rod-coil block polyimide copolymers that are easy to fabricate into mechanically resilient films with acceptable ionic or protonic conductivity at a variety of temperatures. The copolymers consist of short-rigid polyimide rod segments alternating with polyether coil segments. The rods and coil segments can be linear, branched or mixtures of linear and branched segments. The highly incompatible rods and coil segments phase separate, providing nanoscale channels for ion conduction. The polyimide segments provide dimensional and mechanical stability and can be functionalized in a number of ways to provide specialized functions for a given application. These rod-coil black polyimide copolymers are particularly useful in the preparation of ion conductive membranes for use in the manufacture of fuel cells and lithium based polymer batteries.

  18. Design and Control of a 1-DOF MRI Compatible Pneumatically Actuated Robot with Long Transmission Lines.

    PubMed

    Yang, Bo; Tan, U-Xuan; McMillan, Alan; Gullapalli, Rao; Desai, Jaydev P

    2011-12-01

    This paper presents the design and control of an MRI-compatible 1-DOF needle driver robot and its precise position control using pneumatic actuation with long transmission lines. MRI provides superior image quality compared to other imaging modalities such as CT or ultrasound, but imposes severe limitations on the material and actuator choice (to prevent image distortion) due to its strong magnetic field. We are primarily interested in developing a pneumatically actuated breast biopsy robot with a large force bandwidth and precise targeting capability during radio-frequency ablation (RFA) of breast tumor, and exploring the possibility of using long pneumatic transmission lines from outside the MRI room to the device in the magnet to prevent any image distortion whatsoever. This paper presents a model of the entire pneumatic system. The pneumatic lines are approximated by a first order system with time delay, because its dynamics are governed by the telegraph equation with varying coefficients and boundary conditions, which cannot be solved precisely. The slow response of long pneumatic lines and valve subsystems make position control challenging. This is further compounded by the presence of non-uniform friction in the device. Sliding mode control (SMC) was adopted, where friction was treated as an uncertainty term to drive the system onto the sliding surface. Three different controllers were designed, developed, and evaluated to achieve precise position control of the RFA probe. Experimental results revealed that all SMCs gave satisfactory performance with long transmission lines. We also performed several experiments with a 3-DOF fiber-optic force sensor attached to the needle driver to evaluate the performance of the device in the MRI under continuous imaging. PMID:22058649

  19. Design and Control of a 1-DOF MRI Compatible Pneumatically Actuated Robot with Long Transmission Lines

    PubMed Central

    Yang, Bo; Tan, U-Xuan; McMillan, Alan; Gullapalli, Rao; Desai, Jaydev P.

    2011-01-01

    This paper presents the design and control of an MRI-compatible 1-DOF needle driver robot and its precise position control using pneumatic actuation with long transmission lines. MRI provides superior image quality compared to other imaging modalities such as CT or ultrasound, but imposes severe limitations on the material and actuator choice (to prevent image distortion) due to its strong magnetic field. We are primarily interested in developing a pneumatically actuated breast biopsy robot with a large force bandwidth and precise targeting capability during radio-frequency ablation (RFA) of breast tumor, and exploring the possibility of using long pneumatic transmission lines from outside the MRI room to the device in the magnet to prevent any image distortion whatsoever. This paper presents a model of the entire pneumatic system. The pneumatic lines are approximated by a first order system with time delay, because its dynamics are governed by the telegraph equation with varying coefficients and boundary conditions, which cannot be solved precisely. The slow response of long pneumatic lines and valve subsystems make position control challenging. This is further compounded by the presence of non-uniform friction in the device. Sliding mode control (SMC) was adopted, where friction was treated as an uncertainty term to drive the system onto the sliding surface. Three different controllers were designed, developed, and evaluated to achieve precise position control of the RFA probe. Experimental results revealed that all SMCs gave satisfactory performance with long transmission lines. We also performed several experiments with a 3-DOF fiber-optic force sensor attached to the needle driver to evaluate the performance of the device in the MRI under continuous imaging. PMID:22058649

  20. Torsional actuation with extension-torsion composite coupling and a magnetostrictive actuator

    NASA Astrophysics Data System (ADS)

    Bothwell, Christopher M.; Chandra, Ramesh; Chopra, Inderjit

    1995-04-01

    An analytical-experimental study of using magnetostrictive actuators in conjunction with an extension-torsion coupled composite tube to actuate a rotor blade trailing-edge flap to actively control helicopter vibration is presented. Thin walled beam analysis based on Vlasov theory was used to predict the induced twist and extension in a composite tube with magnetostrictive actuation. The study achieved good correlation between theory and experiment. The Kevlar-epoxy systems showed good correlation between measured and predicted twist values.

  1. Optimal satellite formation reconfiguration actuated by inter-satellite electromagnetic forces

    NASA Astrophysics Data System (ADS)

    Cai, Wei-wei; Yang, Le-ping; Zhu, Yan-wei; Zhang, Yuan-wen

    2013-08-01

    The inter-satellite electromagnetic forces generated by the magnetic dipoles on neighboring satellites provide an attractive control actuation alternative for satellite formation flight due to the prominent advantages of no propellant consumption or plume contamination. However, the internal force nature as well as the inherent high nonlinearity and coupling of electromagnetic forces bring unique dynamic characteristics and challenges. This paper investigates the nonlinear translational dynamics, trajectory planning and control of formation reconfiguration actuated by inter-satellite electromagnetic forces. The nonlinear translational dynamic model is derived by utilizing analytical mechanics theory; and analysis on the dynamic characteristics is put forward. Optimal reconfiguration trajectories of electromagnetic force actuated formation are studied by applying optimal control theory and the Gauss pseudospectral method. Considering the high nonlinearity and uncertainty in the dynamic model, an inner-and-outer loop combined control strategy based on feedback linearization theory and adaptive terminal sliding mode control is proposed with finite-time convergence capability and good robust performance. Theoretical analysis and numerical simulation results are presented to validate the feasibility of the proposed translational model, reconfiguration trajectory optimization approach and control strategy.

  2. Electromechanical characteristic analysis of a dielectric electroactive polymer (DEAP) actuator

    NASA Astrophysics Data System (ADS)

    Zhu, Yinlong; Zhou, Hongpin; Wang, Huaming

    2015-10-01

    To assist in the design and optimization of dielectric electroactive polymer (DEAP) actuators, an analytical model for the electromechanical response of cone DEAP actuators is developed. Using the Yeoh form strain energy potential and the Maxwell stress tensor, the constitutive relationship of the DEAP that accounts for the electromechanical coupling behavior is deduced. The equilibrium equations of DEAP actuators with a cone configuration are derived and an analytical model is then proposed. With this model, the actuation characteristics of the DEAP actuator, including actuation displacement, force output and efficiency can be calculated. Additionally, the principal stresses and principal stretch ratio of the membrane under different actuation voltages can be determined, along with the wrinkling failure mode of DEAP actuators. The experimental results for the DEAP actuator matched the numerical results determined using the proposed model. As such, the proposed work is beneficial as a guide for the design optimization of DEAP actuators.

  3. Radial brake assembly for a control rod drive

    SciTech Connect

    Hekmati, A.; Gibo, E.Y.

    1992-04-07

    This patent describes a brake assembly for a control rod drive for selectively preventing travel of a control rod in a nuclear reactor vessel. It comprises a shaft having a longitudinal centerline axis; means for selectively rotating the shaft in a first direction and in a second direction, opposite to the first direction; a stationary housing having a central aperture receiving the shaft; a frame fixedly joined to the housing and having a guide hole; a rotor disc fixedly connected to the shaft for rotation therewith and having at least one rotor tooth extending radially outwardly from a perimeter thereof, the rotor tooth having a locking surface and an inclined surface extending therefrom in a circumferential direction; a brake member disposed adjacent to the rotor disc perimeter and including a base, at least one braking tooth having a locking surface extending therefrom in a circumferential direction, and a plunger extending radially outwardly from the base and slidably joined to the frame through the guide hole; the rotor tooth and the braking tooth being complementary to each other; and means for selectively positioning the brake member in a deployed position abutting the rotor disc perimeter for allowing the braking tooth locking surface to contact the rotor tooth locking surface for preventing rotation of the shaft in the first direction, and in a retracted position spaced radially away from the rotor disc for allowing the rotor disc and the shaft to rotate without restraint from the brake member, the positioning means including a tubular solenoid fixedly joined to the frame and having a central bore disposed around the brake member plunger and effective for sliding the brake member plunger relative to the frame for positioning the brake member in the deployed and retracted positions.

  4. Study of Unsteady Flow Actuation Produced by Surface Plasma Actuator on 2-D Airfoil

    NASA Astrophysics Data System (ADS)

    Phan, Minh Khang; Shin, Jichul

    2014-10-01

    Effect of flow actuation driven by low current continuous or pulsed DC surface glow discharge plasma actuator is studied. Schlieren image of induced flow on flat plate taken at a high repetition rate reveals that the actuation is mostly initiated near the cathode. Assuming that the actuation is mostly achieved by ions in the cathode sheath region, numerical model for the source of flow actuation is obtained by analytical estimation of ion pressure force created in DC plasma sheath near the cathode and added in momentum equation as a body force term. Modeled plasma flow actuator is simulated with NACA0012 airfoil oscillating over a certain range of angle of attack (AoA) at specific reduced frequencies of airfoil. By changing actuation authority according to the change in AoA, stabilization of unsteady flow field is improved and hence steady aerodynamic performance can be maintained. Computational result shows that plasma actuation is only effective in modifying aerodynamic characteristics of separated flow. It turns out that plasma pulse frequency should be tuned for optimal performance depending on phase angle and rotating speed. The actuation authority can be parameterized by a ratio between plasma pulse frequency and reduced frequency.

  5. Serpentine Robot Arm Contains Electromagnetic Actuators

    NASA Technical Reports Server (NTRS)

    Moya, Israel A.; Studer, Philip A.

    1994-01-01

    Identical modules assembled into flexible robot arm configured in serpentlike fashion to manipulate objects while avoiding obstacles. Each module includes integral electromagnetic actuators energized selectively to produce variety of motions, stationary configurations, and combinations thereof.

  6. Surface chemistry driven actuation in nanoporous gold

    SciTech Connect

    Biener, J; Wittstock, A; Zepeda-Ruiz, L; Biener, M M; Zielasek, V; Kramer, D; Viswanath, R N; Weissmuller, J; Baumer, M; Hamza, A V

    2008-04-14

    Although actuation in biological systems is exclusively powered by chemical energy, this concept has not been realized in man-made actuator technologies, as these rely on generating heat or electricity first. Here, we demonstrate that surface-chemistry driven actuation can be realized in high surface area materials such as nanoporous gold. For example, we achieve reversible strain amplitudes in the order of a few tenths of a percent by alternating exposure of nanoporous Au to ozone and carbon monoxide. The effect can be explained by adsorbate-induced changes of the surface stress, and can be used to convert chemical energy directly into a mechanical response thus opening the door to surface-chemistry driven actuator and sensor technologies.

  7. Electromechanically active polymer blends for actuation

    NASA Astrophysics Data System (ADS)

    Su, Ji; Ounaies, Zoubeida; Harrison, Joycelyn S.; Bar-Cohen, Yoseph; Leary, Sean P.

    2000-06-01

    Actuator mechanisms that are lightweight, durable, and efficient are needed to support telerobotic requirements, for future NASA missions. In this work, we present a series of electromechanically active polymer blends that can potentially be used as actuators for a variety of applications. This polymer blend combines an electrostrictive graft-elastomer with a ferroelectric poly (vinylidene fluoride-trifluoroethylene) polymer. Mechanical and piezoelectric properties of the blends as a function of temperature, frequency and relative composition of the two constituents in the blends have been studied. Electric field induced strain response of the blend films has also been studied as a function of the relative composition. A bending actuator device was developed incorporating the use of the polymer blend materials. The results and the possible effects of the combination of piezoelectricity and electrostriction in a material system are presented and discussed. This type of analysis may enable the design of blend compositions with optimal strain, mechanical, and dielectric properties for specific actuator applications.

  8. Considerations for Contractile Electroactive Materials and Actuators

    SciTech Connect

    Lenore Rasmussen, David Schramm, Paul Rasmussen, Kevin Mullaly, Ras Labs, LLC, Intelligent Materials for Prosthetics & Automation, Lewis D. Meixler, Daniel Pearlman and Alice Kirk

    2011-05-23

    Ras Labs produces contractile electroactive polymer (EAP) based materials and actuators that bend, swell, ripple, and contract (new development) with low electric input. In addition, Ras Labs produces EAP materials that quickly contract and expand, repeatedly, by reversing the polarity of the electric input, which can be cycled. This phenomenon was explored using molecular modeling, followed by experimentation. Applied voltage step functions were also investigated. High voltage steps followed by low voltage steps produced a larger contraction followed by a smaller contraction. Actuator control by simply adjusting the electric input is extremely useful for biomimetic applications. Muscles are able to partially contract. If muscles could only completely contract, nobody could hold an egg, for example, without breaking it. A combination of high and low voltage step functions could produce gross motor function and fine manipulation within the same actuator unit. Plasma treated electrodes with various geometries were investigated as a means of providing for more durable actuation.

  9. Research on Plasma Synthetic Jet Actuator

    NASA Astrophysics Data System (ADS)

    Che, X. K.; Nie, W. S.; Hou, Z. Y.

    2011-09-01

    Circular dielectric barrier surface discharge (DBDs) actuator is a new concept of zero mass synthetic jet actuator. The characteristic of discharge and flow control effect of annular-circular plasma synthetic jet actuator has been studied by means of of numerical simulation and experiment. The discharge current density, electron density, electrostatic body force density and flowfield have been obtained. The results show annular-circular actuator can produce normal jet whose velocity will be greater than 2.0 m/s. The jet will excite circumfluence. In order to insure the discharge is generated in the exposed electrode annular and produce centripetal and normal electrostatic body force, the width and annular diameter of exposed electrode must be big enough, or an opposite phase drove voltage potential should be applied between the two electrodes.

  10. Considerations for contractile electroactive materials and actuators

    NASA Astrophysics Data System (ADS)

    Rasmussen, Lenore; Schramm, David; Rasmussen, Paul; Mullally, Kevin; Meixler, Lewis D.; Pearlman, Daniel; Kirk, Alice

    2011-04-01

    Ras Labs produces contractile electroactive polymer (EAP) based materials and actuators that bend, swell, ripple, and contract (new development) with low electric input. In addition, Ras Labs produces EAP materials that quickly contract and expand, repeatedly, by reversing the polarity of the electric input, which can be cycled. This phenomenon was explored using molecular modeling, followed by experimentation. Applied voltage step functions were also investigated. High voltage steps followed by low voltage steps produced a larger contraction followed by a smaller contraction. Actuator control by simply adjusting the electric input is extremely useful for biomimetic applications. Muscles are able to partially contract. If muscles could only completely contract, nobody could hold an egg, for example, without breaking it. A combination of high and low voltage step functions could produce gross motor function and fine manipulation within the same actuator unit. Plasma treated electrodes with various geometries were investigated as a means of providing for more durable actuation.

  11. Tension Stiffened and Tendon Actuated Manipulator

    NASA Technical Reports Server (NTRS)

    Doggett, William R. (Inventor); Dorsey, John T. (Inventor); Ganoe, George G. (Inventor); King, Bruce D. (Inventor); Jones, Thomas C. (Inventor); Mercer, Charles D. (Inventor); Corbin, Cole K. (Inventor)

    2015-01-01

    A tension stiffened and tendon actuated manipulator is provided performing robotic-like movements when acquiring a payload. The manipulator design can be adapted for use in-space, lunar or other planetary installations as it is readily configurable for acquiring and precisely manipulating a payload in both a zero-g environment and in an environment with a gravity field. The manipulator includes a plurality of link arms, a hinge connecting adjacent link arms together to allow the adjacent link arms to rotate relative to each other and a cable actuation and tensioning system provided between adjacent link arms. The cable actuation and tensioning system includes a spreader arm and a plurality of driven and non-driven elements attached to the link arms and the spreader arm. At least one cable is routed around the driven and non-driven elements for actuating the hinge.

  12. Sensors and actuators inherent in biological species

    NASA Astrophysics Data System (ADS)

    Taya, Minoru; Stahlberg, Rainer; Li, Fanghong; Zhao, Ying Joyce

    2007-04-01

    This paper addresses examples of sensing and active mechanisms inherent in some biological species where both plants and animals cases are discussed: mechanosensors and actuators in Venus Fly Trap and cucumber tendrils, chemosensors in insects, two cases of interactions between different kingdoms, (i) cotton plant smart defense system and (ii) bird-of-paradise flower and hamming bird interaction. All these cases lead us to recognize how energy-efficient and flexible the biological sensors and actuators are. This review reveals the importance of integration of sensing and actuation functions into an autonomous system if we make biomimetic design of a set of new autonomous systems which can sense and actuate under a number of different stimuli and threats.

  13. Actuators Based on Liquid Crystalline Elastomer Materials

    PubMed Central

    Jiang, Hongrui; Li, Chensha; Huang, Xuezhen

    2013-01-01

    Liquid crystalline elastomers (LCEs) exhibit a number of remarkable physical effects, including the unique, high-stroke reversible mechanical actuation when triggered by external stimuli. This article reviews some recent exciting developments in the field of LCEs materials with an emphasis on their utilization in actuator applications. Such applications include artificial muscles, industrial manufacturing, health and microelectromechanical systems (MEMS). With suitable synthetic and preparation pathways and well-controlled actuation stimuli, such as heat, light, electric and magnetic field, excellent physical properties of LCE materials can be realized. By comparing the actuating properties of different systems, general relationships between the structure and the property of LCEs are discussed. How these materials can be turned into usable devices using interdisciplinary techniques is also described. PMID:23648966

  14. Nylon-muscle-actuated robotic finger

    NASA Astrophysics Data System (ADS)

    Wu, Lianjun; Jung de Andrade, Monica; Rome, Richard S.; Haines, Carter; Lima, Marcio D.; Baughman, Ray H.; Tadesse, Yonas

    2015-04-01

    This paper describes the design and experimental analysis of novel artificial muscles, made of twisted and coiled nylon fibers, for powering a biomimetic robotic hand. The design is based on circulating hot and cold water to actuate the artificial muscles and obtain fast finger movements. The actuation system consists of a spring and a coiled muscle within a compliant silicone tube. The silicone tube provides a watertight, expansible compartment within which the coiled muscle contracts when heated and expands when cooled. The fabrication and characterization of the actuating system are discussed in detail. The performance of the coiled muscle fiber in embedded conditions and the related characteristics of the actuated robotic finger are described.

  15. Self-actuating reactor shutdown system

    DOEpatents

    Barrus, Donald M.; Brummond, Willian A; Peterson, Leslie F.

    1988-01-01

    A control system for the automatic or self-actuated shutdown or "scram" of a nuclear reactor. The system is capable of initiating scram insertion by a signal from the plant protection system or by independent action directly sensing reactor conditions of low-flow or over-power. Self-actuation due to a loss of reactor coolant flow results from a decrease of pressure differential between the upper and lower ends of an absorber element. When the force due to this differential falls below the weight of the element, the element will fall by gravitational force to scram the reactor. Self-actuation due to high neutron flux is accomplished via a valve controlled by an electromagnet and a thermionic diode. In a reactor over-power, the diode will be heated to a change of state causing the electromagnet to be shorted thereby actuating the valve which provides the changed flow and pressure conditions required for scramming the absorber element.

  16. Mirrors Containing Biomimetic Shape-Control Actuators

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph; Mouroulis, Pantazis; Bao, Xiaoqi; Sherrit, Stewart

    2003-01-01

    Curved mirrors of a proposed type would comprise lightweight sheets or films containing integral, biologically inspired actuators for controlling their surface figures. These mirrors could be useful in such applications as collection of solar energy, focusing of radio beams, and (provided sufficient precision could be achieved) imaging. These mirrors were originally intended for use in outer space, but it should also be possible to develop terrestrial versions. Several prior NASA Tech Briefs articles have described a variety of approaches to the design of curved, lightweight mirrors containing integral shape-control actuators. The primary distinction between the present approach and the prior approaches lies in the actuator design concept, which involves shapes and movements reminiscent of those of a variety of small, multi-armed animals. The shape and movement of an actuator of this type can also be characterized as reminiscent of that of an umbrella. This concept can be further characterized as a derivative of that of multifinger grippers, the fingers of which are bimorph bending actuators (see Figure 1). The fingers of such actuators can be strips containing any of a variety of materials that have been investigated for use as actuators, including such electroactive polymers as ionomeric polymer/metal composites (IPMCs), ferroelectric polymers, and grafted elastomers. A mirror according to this proposal would be made from a sheet of one of the actuator composites mentioned above. The design would involve many variables, including the pre-curvature and stiffness of the mirror sheet, the required precision of figure control, the required range of variation in focal length (see Figure 2), the required precision of figure control for imaging or non-imaging use, the bending and twisting moments needed to effect the required deformations, and voltage-tomoment coefficients of the actuators, and the voltages accordingly required for actuation. A typical design would call

  17. Eulerian Formulation of Spatially Constrained Elastic Rods

    NASA Astrophysics Data System (ADS)

    Huynen, Alexandre

    Slender elastic rods are ubiquitous in nature and technology. For a vast majority of applications, the rod deflection is restricted by an external constraint and a significant part of the elastic body is in contact with a stiff constraining surface. The research work presented in this doctoral dissertation formulates a computational model for the solution of elastic rods constrained inside or around frictionless tube-like surfaces. The segmentation strategy adopted to cope with this complex class of problems consists in sequencing the global problem into, comparatively simpler, elementary problems either in continuous contact with the constraint or contact-free between their extremities. Within the conventional Lagrangian formulation of elastic rods, this approach is however associated with two major drawbacks. First, the boundary conditions specifying the locations of the rod centerline at both extremities of each elementary problem lead to the establishment of isoperimetric constraints, i.e., integral constraints on the unknown length of the rod. Second, the assessment of the unilateral contact condition requires, in principle, the comparison of two curves parametrized by distinct curvilinear coordinates, viz. the rod centerline and the constraint axis. Both conspire to burden the computations associated with the method. To streamline the solution along the elementary problems and rationalize the assessment of the unilateral contact condition, the rod governing equations are reformulated within the Eulerian framework of the constraint. The methodical exploration of both types of elementary problems leads to specific formulations of the rod governing equations that stress the profound connection between the mechanics of the rod and the geometry of the constraint surface. The proposed Eulerian reformulation, which restates the rod local equilibrium in terms of the curvilinear coordinate associated with the constraint axis, describes the rod deformed configuration

  18. Handbook of actuators and edge alignment sensors

    SciTech Connect

    Krulewich, D A

    1992-11-01

    This actuator and sensor handbook was developed during a cooperative project between the NASA-Marshall Space Flight Center, the SDI-Directed Energy Program and LLNL. The common purpose of the joint effort was to develop precision actuators and sensors for the NASA initiated SpacE Laser ENE-rgy Program (SELENE). The purpose of the SELENE Program is to develop a highly cost effective segmented adaptive optics system for beaming laser power directly to spacecraft in earth orbit.

  19. Redundancy of hydraulic flight control actuators

    NASA Technical Reports Server (NTRS)

    Chenoweth, C. C.; Ryder, D. R.

    1976-01-01

    The constraint of requiring airplanes to have inherent aerodynamic stability can be removed by using active control systems. The resulting airplane requires control system reliability approaching that of the basic airframe. Redundant control actuators can be used to achieve the required reliability, but create mechanization and operational problems. Of numerous candidate systems, two different approaches to solving the problems associated with redundant actuators which appear the most likely to be used in advanced airplane control systems are described.

  20. Unusual and Superfast Temperature-Triggered Actuators.

    PubMed

    Jiang, Shaohua; Liu, Fangyao; Lerch, Arne; Ionov, Leonid; Agarwal, Seema

    2015-09-01

    A superfast actuator based on a bilayer fibrous mat shows folding/unfolding and the formation of 3D structures in a fraction of a second. The actuation is reversible for many cycles without losing its form and size, with unfolding at room temperature and folding above 35 °C. The system is promising for making 3D bioscaffolds, electrodes, and micro-/macroactuators. PMID:26186175

  1. Electromechanical flight control actuator, volume 1

    NASA Technical Reports Server (NTRS)

    1978-01-01

    An electromechanical actuator was developed that will follow a proportional control command with minimum wasted energy to demonstrate the feasibility of meeting space vehicle actuator requirements using advanced electromechanical concepts. The approach was restricted to a four-channel redundant configuration. Each channel has independent drive and control electronics, a brushless electric motor with brake, and velocity and position feedback transducers. A differential gearbox sums the output velocities of the motors. Normally, two motors are active and the other two are braked.

  2. Digital flight control actuation system study

    NASA Technical Reports Server (NTRS)

    Rossing, R.; Hupp, R.

    1974-01-01

    Flight control actuators and feedback sensors suitable for use in a redundant digital flight control system were examined. The most appropriate design approach for an advanced digital flight control actuation system for development and use in a fly-by-wire system was selected. The concept which was selected consisted of a PM torque motor direct drive. The selected system is compatible with concurrent and independent development efforts on the computer system and the control law mechanizations.

  3. Design and application of shape memory actuators

    NASA Astrophysics Data System (ADS)

    Mertmann, M.; Vergani, G.

    2008-05-01

    The use of shape memory alloys in actuators allows the development of robust, simple and lightweight elements for application in a multitude of different industries. Over the years, the intermetallic compound Nickel-Titanium (NiTi or Nitinol) together with its ternary and quaternary derivates has gained general acceptance as a standard alloy. Even though as many as 99% of all shape memory actuator applications make use of Nitinol there are certain properties of this alloy system which require further research in order to find improvements and new markets: • Lack of higher transformation temperatures in the available alloys in order to open the field of automotive applications (Mf temperature > 80 °C) • Non-linearity in the electrical resistivity in order to improve the controllability of the actuator, • Wide hysteresis in the temperature-vs.-strain behaviour, which has a signi-ficant effect on both, the dynamics of the actuator and its controllability. Hence, there is a constant strive in the field towards an improvement of the related properties. However, these improvements are not always just alloy composition related. There is also a tremendous potential in the thermomechanical treatment of the material and in the design of the actuator. Significant improvement steps are already possible if the usage of the existent materials is optimized for the projected application and if the actuator system is designed in the most efficient way. This paper provides an overview about existent designs, applications and alloys for use in actuators, as well as examples of new shape memory actuator application with improved performance. It also gives an overview about general design rules and reflects about the strengths of the material and the related opportunities for its application.

  4. Microelectromechanical Systems Actuator Based Reconfigurable Printed Antenna

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N. (Inventor)

    2005-01-01

    A polarization reconfigurable patch antenna is disclosed. The antenna includes a feed element, a patch antenna element electrically connected to the feed element, and at least one microelectromechanical systems (MEMS) actuator, with a partial connection to the patch antenna element along an edge of the patch antenna element. The polarization of the antenna can be switched between circular polarization and linear polarization through action of the at least one MEMS actuator.

  5. Application of discrete time sliding mode control to a spacecraft in 6DoF with parameter identification

    NASA Astrophysics Data System (ADS)

    Lincoln, N. K.; Veres, S. M.

    2010-11-01

    This article presents the application of two discrete-time sliding mode controllers, developed in conjunction with a potential function guidance method, to provide control in both position and attitude for a rigid, holonomic spacecraft body using thrusters only. Identification of mass and inertial matrix parameters is also included. Both controllers are demonstrated for their effectiveness under realistic actuator constraints. One of the controllers is also implemented on hardware in a representative 5 degrees of freedom (5DoF) testbed environment to show the practical performance of the methods.

  6. 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.

  7. 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.

  8. 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.

  9. Large stroke actuators for adaptive optics

    NASA Astrophysics Data System (ADS)

    Fernández, B.; Kubby, J. A.

    2006-01-01

    In this paper we review the use of a 3-dimensional MEMS fabrication process to prototype long stroke (>10 μm) actuators as are required for use in future adaptive optics systems in astronomy and vision science. The Electrochemical Fabrication (EFAB TM) process that was used creates metal micro-structures by electroplating multiple, independently patterned layers. The process has the design freedom of rapid prototyping where multiple patterned layers are stacked to build structures with virtually any desired geometry, but in contrast has much greater precision, the capability for batch fabrication and provides parts in engineering materials such as nickel. The design freedom enabled by this process has been used to make both parallel plate and comb drive actuator deformable mirror designs that can have large vertical heights of up to 1 mm. As the thickness of the sacrificial layers used to release the actuator is specified by the designer, rather than by constraints of the fabrication process, the design of large-stroke actuators is straightforward and does not require any new process development. Since the number of material layers in the EFAB TM process is also specified by the designer it has been possible to gang multiple parallel plate actuators together to decrease the voltage required for long-stroke actuators.

  10. Actuators For A Segmented Mirror Control System

    NASA Astrophysics Data System (ADS)

    Gabor, George

    1983-11-01

    The active control of segmented mirrors requires actuators to move the segments in response to perturbations. Each segment of the University of California Ten Meter Telescope has three of its six rigid-body degrees of freedom actively controlled; piston and tilt about two axes. The system design requires the actuator to carry a load that varies as the telescope moves from zenith to horizon. The maximum load is one third of the segment mass, about 150kg. The system design also needs actuator adjustment resolution less than 20nm over a range of 3mm with a 2µm/sec response rate. Actuators which satisfy these requirements have been designed, built, and tested. A torque motor turns a screw shaft whose axial load is taken by a roller thrust bearing. Simultaneously the screw drives a roller nut to position the mirror segment. The roller screw converts rotary to linear motion with nanometer smoothness over a large dynamic range. A stick-slip behavior in the thrust bearing makes the mechanical system non-linear for small motions. Each actuator has a microprocessor-controlled servo loop and the servo loop algorithm compensates for this non-linear behavior. The actuator design and servo loop algorithm are described and the results of servo loop performance tests are given.

  11. Actuators for a segmented mirror control system.

    NASA Astrophysics Data System (ADS)

    Gabor, George

    1984-01-01

    The active control of segmented mirrors requires actuators to move the segments in response to perturbations. Each segment of the University of California Ten Meter Telescope has three of its six rigid-body degrees of freedom actively controlled; piston and tilt about two axes. The system design requires the actuator to carry a load that varies as the telescope moves from zenith to horizon. The maximum load is one third of the segment mass, about 150kg. The system design also needs actuator adjustment resolution less than 20nm over a range of 3mm with a 2 m/sec response rate. Actuators which satisfy these requirements have been designed, built, and tested. A torque motor turns a screw shaft whose axial load is taken by a roller thrust bearing. Simultaneously the screw drives a roller nut to position the mirror segment. The roller screw converts rotary to linear motion with nanometer smoothness over a large dynamic range. A stick-slip behavior in the thrust bearing makes the mechanical system non-linear for small motions. Each actuator has a microprocessor-controlled servo loop and the servo loop algorithm compensates for this non-linear behavior. The actuator design and servo loop algorithm are described and the results of servo loop performance tests are given.

  12. Networked Rectenna Array for Smart Material Actuators

    NASA Technical Reports Server (NTRS)

    Choi, Sang H.; Golembiewski, Walter T.; Song, Kyo D.

    2000-01-01

    The concept of microwave-driven smart material actuators is envisioned as the best option to alleviate the complexity associated with hard-wired control circuitry. Networked rectenna patch array receives and converts microwave power into a DC power for an array of smart actuators. To use microwave power effectively, the concept of a power allocation and distribution (PAD) circuit is adopted for networking a rectenna/actuator patch array. The PAD circuit is imbedded into a single embodiment of rectenna and actuator array. The thin-film microcircuit embodiment of PAD circuit adds insignificant amount of rigidity to membrane flexibility. Preliminary design and fabrication of PAD circuitry that consists of a few nodal elements were made for laboratory testing. The networked actuators were tested to correlate the network coupling effect, power allocation and distribution, and response time. The features of preliminary design are 16-channel computer control of actuators by a PCI board and the compensator for a power failure or leakage of one or more rectennas.

  13. Sweeping Jet Actuator in a Quiescent Environment

    NASA Technical Reports Server (NTRS)

    Koklu, Mehti; Melton, Latunia P.

    2013-01-01

    This study presents a detailed analysis of a sweeping jet (fluidic oscillator) actuator. The sweeping jet actuator promises to be a viable flow control actuator candidate due to its simple, no moving part structure and its high momentum, spatially oscillating flow output. Hot-wire anemometer and particle image velocimetry measurements were carried out with an emphasis on understanding the actuator flow field in a quiescent environment. The time averaged, fluctuating, and instantaneous velocity measurements are provided. A modified actuator concept that incorporates high-speed solenoid valves to control the frequency of oscillation enabled phase averaged measurements of the oscillating jet. These measurements reveal that in a given oscillation cycle, the oscillating jet spends more time on each of the Coanda surfaces. In addition, the modified actuator generates four different types of flow fields, namely: a non oscillating downward jet, a non oscillating upward jet, a non oscillating straight jet, and an oscillating jet. The switching from an upward jet to a downward jet is accomplished by providing a single pulse from the solenoid valve. Once the flow is switched, the flow stays there until another pulse is received. The oscillating jet is compared with a non oscillating straight jet, which is a typical planar turbulent jet. The results indicate that the oscillating jet has a higher (5 times) spreading rate, more flow entrainment, and higher velocity fluctuations (equal to the mean velocity).

  14. Assessment of Heat Up of Shut-Off Rods of 540 MWe IPHWRs Using CFD Technique

    SciTech Connect

    Yadav, D.H.; Pathak, N.K.; Datta, D.; Dharne, S.P.

    2006-07-01

    There are two independent, fast acting and diverse reactor shutdown systems in 540 MWe Indian PHWR viz. Shut down System no.1 (SDS no.1) and Shut down System no.2. Either of them is fully capable of reactor shut down with adequate shutdown margin. SDS no.1 consists of 28 shut-off rods (SRs) which are Stainless Steel (SS)-Cadmium- Stainless Steel sandwiched rods. The SRs remain in parked out condition during reactor operation. When any of the reactor operating conditions call for a reactor trip or the operator manually actuate the system the shut-off rods are dropped into the reactor core. The SRs take about 2.5 Sec. to drop into the core. The system adds about 72 mk negative reactivity into the core, thus bringing the reactor to a safe sub-critical condition. During reactor power operation, the Calandria is full of moderator and bottom tip of SR is partly immersed in the moderator. When a SR enters the core as a part of on-line testing or inadvertently during reactor operation, due to neutron flux heat is generated in the SR, which is carried away by the moderator. The present study is done to predict the maximum temperature of Cadmium inside the Cadmium sandwiched SS elements of SR, when the rod partly enters inside the Calandria and the reactor continues to operate at or close to full power i.e. when the heat generation rate in SRs is the maximum. 3-Dimensional temperature distribution in the shut-off rod is predicted using CFD (Computational Fluid Dynamics) techniques. (authors)

  15. Electrically actuated multiple store launcher

    NASA Astrophysics Data System (ADS)

    Marshall, Frank P.; Travor, Bruce W.

    1991-12-01

    This invention comprises a multi-store, electrical pulse initiated launcher that fits into, and is electrically connected with a transporting vehicle and that contains sequentially stacked assemblies. An electrical pulse from the transporting vehicle causes a resistor with the least value to transfer the electric sufficient gas pressure to force the store out of the launcher. The present invention discloses an electrically-actuated, multi-store dispenser wherein an initial electrical charge ignites gas cartridges causing sequential launching of stores from their tandem position inside a launch container. In some environments, it is desirable to dispense multiple stores from a launch vehicle, for instance sonobuoys, in dense patterns. Due to physical limitations of space in the dispensing vehicle, an effort was made to miniaturize the active components inside the store and therefore reduce the overall outer dimensions thereof. Once the size of the store was reduced, in order to meet the demands of the denser patterns, the inside of the individual launch containers were modified to allow each to hold and dispense more than one store. This new type of launch container, in addition to maintaining the size requirement dictated by the transporting vehicle, is operated by the vehicle's electrical system.

  16. High-pressure microhydraulic actuator

    DOEpatents

    Mosier, Bruce P [San Francisco, CA; Crocker, Robert W [Fremont, CA; Patel, Kamlesh D [Dublin, CA

    2008-06-10

    Electrokinetic ("EK") pumps convert electric to mechanical work when an electric field exerts a body force on ions in the Debye layer of a fluid in a packed bed, which then viscously drags the fluid. Porous silica and polymer monoliths (2.5-mm O.D., and 6-mm to 10-mm length) having a narrow pore size distribution have been developed that are capable of large pressure gradients (250-500 psi/mm) when large electric fields (1000-1500 V/cm) are applied. Flowrates up to 200 .mu.L/min and delivery pressures up to 1200 psi have been demonstrated. Forces up to 5 lb-force at 0.5 mm/s (12 mW) have been demonstrated with a battery-powered DC-DC converter. Hydraulic power of 17 mW (900 psi@ 180 uL/min) has been demonstrated with wall-powered high voltage supplies. The force and stroke delivered by an actuator utilizing an EK pump are shown to exceed the output of solenoids, stepper motors, and DC motors of similar size, despite the low thermodynamic efficiency.

  17. Low backlash direct drive actuator

    DOEpatents

    Kuklo, T.C.

    1994-10-25

    A low backlash direct drive actuator is described which comprises a motor such as a stepper motor having at least 200 steps per revolution; a two part hub assembly comprising a drive hub coaxially attached to the shaft of the motor and having a plurality of drive pins; a driven hub having a plurality of bores in one end thereof in alignment with the drive pins in the drive hub and a threaded shaft coaxially mounted in an opposite end of the driven hub; and a housing having a central bore therein into which are fitted the drive hub and driven hub, the housing having a motor mount on one end thereof to which is mounted the stepper motor, and a closed end portion with a threaded opening therein coaxial with the central bore in the housing and receiving therein the threaded shaft attached to the driven hub. Limit switches mounted to the housing cooperate with an enlarged lip on the driven hub to limit the lateral travel of the driven hub in the housing, which also acts to limit the lateral travel of the threaded shaft which functions as a lead screw. 10 figs.

  18. Low backlash direct drive actuator

    DOEpatents

    Kuklo, Thomas C.

    1994-01-01

    A low backlash direct drive actuator is described which comprises a motor such as a stepper motor having at least 200 steps per revolution; a two part hub assembly comprising a drive hub coaxially attached to the shaft of the motor and having a plurality of drive pins; a driven hub having a plurality of bores in one end thereof in alignment with the drive pins in the drive hub and a threaded shaft coaxially mounted in an opposite end of the driven hub; and a housing having a central bore therein into which are fitted the drive hub and driven hub, the housing having a motor mount on one end thereof to which is mounted the stepper motor, and a closed end portion with a threaded opening therein coaxial with the central bore in the housing and receiving therein the threaded shaft attached to the driven hub. Limit switches mounted to the housing cooperate with an enlarged lip on the driven hub to limit the lateral travel of the driven hub in the housing, which also acts to limit the lateral travel of the threaded shaft which functions as a lead screw.

  19. Fully redundant mechanical release actuator

    NASA Technical Reports Server (NTRS)

    Lucy, Melvin H. (Inventor)

    1987-01-01

    A system is described for performing a mechanical release function exhibiting low shock. This system includes two pyrotechnic detents fixed mounted in opposing axial alignment within a cylindrical housing having two mechanical bellows. Two mechanical bellow assemblies, each having one end hermetically bonded to the housing and the other to the respective actuator pin extending from either end of the housing, ensure that all outgassing and contamination from the operation of the pyrotechnic devices will be contained within the housing and bellows. The pin on one end of the assembly is fixed mounted and supported, via a bolt or ball-and-socket joint so that when the charge corresponding to that pin ignites, the entire assembly will exhibit rectilinear movement, including the opposing pin providing the unlatching motion. The release detent pin is supported by a linear bearing and when its corresponding pyrotechnic charge ignites the pin is retracted within the housing producing the same unlatching motion without movement of the entire assembly, thus providing complete mechanical, electrical and pyrotechnic redundancy for the unlatching pin.

  20. Lightweight Exoskeletons with Controllable Actuators

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph; Mavrodis, Constantinos; Melli-Huber, Juan; Fisch, Avi (Alan)

    2004-01-01

    A proposed class of lightweight exoskeletal electromechanical systems would include electrically controllable actuators that would generate torques and forces that, depending on specific applications, would resist and/or assist wearers movements. The proposed systems would be successors to relatively heavy, bulky, and less capable human-strength-amplifying exoskeletal electromechanical systems that have been subjects of research during the past four decades. The proposed systems could be useful in diverse applications in which there are needs for systems that could be donned or doffed easily, that would exert little effect when idle, and that could be activated on demand: examples of such applications include (1) providing controlled movement and/or resistance to movement for physical exercise and (2) augmenting wearers strengths in the performance of military, law-enforcement, and industrial tasks. An exoskeleton according to the proposal would include adjustable lightweight graphite/epoxy struts and would be attached to the wearer's body by belts made of hook-and-pile material. At selected rotary and linear joints, the exoskeleton would be fitted, variously, with lightweight, low-power-consumption rotary and linear brakes, clutches, and motors. The exoskeleton would also be equipped with electronic circuitry for monitoring, control, and possibly communication with external electronic circuits that would perform additional monitoring and control functions.

  1. Larger-Stroke Piezoelectrically Actuated Microvalve

    NASA Technical Reports Server (NTRS)

    Yang, Eui-Hyeok

    2003-01-01

    A proposed normally-closed microvalve would contain a piezoelectric bending actuator instead of a piezoelectric linear actuator like that of the microvalve described in the preceding article. Whereas the stroke of the linear actuator of the preceding article would be limited to approximately equal to 6 micrometers, the stroke of the proposed bending actuator would lie in the approximate range of 10 to 15 micrometers-large enough to enable the microvalve to handle a variety of liquids containing suspended particles having sizes up to 10 m. Such particulate-laden liquids occur in a variety of microfluidic systems, one example being a system that sorts cells or large biomolecules for analysis. In comparison with the linear actuator of the preceding article, the bending actuator would be smaller and less massive. The combination of increased stroke, smaller mass, and smaller volume would be obtained at the cost of decreased actuation force: The proposed actuator would generate a force in the approximate range of 1 to 4 N, the exact amount depending on operating conditions and details of design. This level of actuation force would be too low to enable the valve to handle a fluid at the high pressure level mentioned in the preceding article. The proposal encompasses two alternative designs one featuring a miniature piezoelectric bimorph actuator and one featuring a thick-film unimorph piezoelectric actuator (see figure). In either version, the valve would consume a power of only 0.01 W when actuated at a frequency of 100 Hz. Also, in either version, it would be necessary to attach a soft elastomeric sealing ring to the valve seat so that any particles that settle on the seat would be pushed deep into the elastomeric material to prevent or reduce leakage. The overall dimensions of the bimorph version would be 7 by 7 by 1 mm. The actuator in this version would generate a force of 1 N and a stroke of 10 m at an applied potential of 150 V. The actuation force would be

  2. Control Rod Malfunction at the NRAD Reactor

    SciTech Connect

    Thomas L. Maddock

    2010-05-01

    The neutron Radiography Reactor (NRAD) is a training, research, and isotope (TRIGA) reactor located at the INL. The reactor is normally shut down by the insertion of three control rods that drop into the core when power is removed from electromagnets. During a routine shutdown, indicator lights on the console showed that one of the control rods was not inserted. It was initially thought that the indicator lights were in error because of a limit switch that was out of adjustment. Through further testing, it was determined that the control rod did not drop when the scram switch was initially pressed. The control rod anomaly led to a six month shutdown of the reactor and an in depth investigation of the reactor protective system. The investigation looked into: scram switch operation, console modifications, and control rod drive mechanisms. A number of latent issues were discovered and corrected during the investigation. The cause of the control rod malfunction was found to be a buildup of corrosion in the control rod drive mechanism. The investigation resulted in modifications to equipment, changes to both operation and maintenance procedures, and additional training. No reoccurrences of the problem have been observed since corrective actions were implemented.

  3. DEVICE FOR CONTROLLING INSERTION OF ROD

    DOEpatents

    Beaty, B.J.

    1958-10-14

    A device for rapidly inserting a safety rod into a nuclear reactor upon a given signal or in the event of a power failure in order to prevent the possibility of extensive damage caused by a power excursion is described. A piston is slidably mounted within a vertical cylinder with provision for an electromagnetic latch at the top of the cylinder. This assembly, with a safety rod attached to the piston, is mounted over an access port to the core region of the reactor. The piston is normally latched at the top of the cylinder with the safety rod clear of the core area, however, when the latch is released, the piston and rod drop by their own weight to insert the rod. Vents along the side of the cylinder permit the escape of the air entrapped under the piston over the greater part of the distance, however, at the end of the fall the entrapped air is compressed thereby bringing the safety rod gently to rest, thus providing for a rapid automatic insertion of the rod with a minimum of structural shock.

  4. Granular materials interacting with thin flexible rods

    NASA Astrophysics Data System (ADS)

    Neto, Alfredo Gay; Campello, Eduardo M. B.

    2016-01-01

    In this work, we develop a computational model for the simulation of problems wherein granular materials interact with thin flexible rods. We treat granular materials as a collection of spherical particles following a discrete element method (DEM) approach, while flexible rods are described by a large deformation finite element (FEM) rod formulation. Grain-to-grain, grain-to-rod, and rod-to-rod contacts are fully permitted and resolved. A simple and efficient strategy is proposed for coupling the motion of the two types (discrete and continuum) of materials within an iterative time-stepping solution scheme. Implementation details are shown and discussed. Validity and applicability of the model are assessed by means of a few numerical examples. We believe that robust, efficiently coupled DEM-FEM schemes can be a useful tool to the simulation of problems wherein granular materials interact with thin flexible rods, such as (but not limited to) bombardment of grains on beam structures, flow of granular materials over surfaces covered by threads of hair in many biological processes, flow of grains through filters and strainers in various industrial segregation processes, and many others.

  5. Gelation and mechanical response of patchy rods.

    PubMed

    Kazem, Navid; Majidi, Carmel; Maloney, Craig E

    2015-10-28

    We perform Brownian dynamics simulations to study the gelation of suspensions of attractive, rod-like particles. We show that in detail the rod-rod surface interactions can dramatically affect the dynamics of gelation and the structure and mechanics of the networks that form. If the attraction between the rods is perfectly smooth along their length, they will collapse into compact bundles. If the attraction is sufficiently corrugated or patchy, over time, a rigid space-spanning network will form. We study the structure and mechanical properties of the networks that form as a function of the fraction of the surface, f, that is allowed to bind. Surprisingly, the structural and mechanical properties are non-monotonic in f. At low f, there are not a sufficient number of cross-linking sites to form networks. At high f, rods bundle and form disconnected clusters. At intermediate f, robust networks form. The elastic modulus and yield stress are both non-monotonic in the surface coverage. The stiffest and strongest networks show an essentially homogeneous deformation under strain with rods re-orienting along the extensional axis. Weaker, more clumpy networks at high f re-orient relatively little with strong non-affine deformation. These results suggest design strategies for tailoring surface interactions between rods to yield rigid networks with optimal mechanical properties. PMID:26381995

  6. More on the penetration of yawed rods

    NASA Astrophysics Data System (ADS)

    Rosenberg, Z.; Dekel, E.; Ashuach, Y.

    2006-08-01

    One of the most complex processes, in the field of terminal ballistics, is that of yawed impact of long rods. In spite of many experimental observations, and some analytical modeling, a clear picture of this issue is still lacking. In order to gain some insight into the operating mechanisms, we developed a simple engineering model which considers the yawed rod as a series of small disks. We then define the effective length and diameter of the rod by considering those disks which are going to hit the initial crater which is opened by the impact. We also performed a series of 3D numerical simulations with various L/D tungsten alloy rods impacting a steel target, at yaws in the full range of 0-90^circ. We analyzed the results of these simulations in terms of the normalized penetration (P/D), where D is the rod diameter, and looked for systematic trends in the results for the various rods. The agreement between our model predictions and both experimental data and simulation results is quite good. Based on this agreement we can highlight some new features of the penetration process of yawed rods.

  7. A linear-actuated torsional device to replicate clinically relevant spiral fractures in long bones.

    PubMed

    Edwards, W Brent; Troy, Karen L

    2012-09-01

    To better understand the mechanisms underlying spiral fracture we would like to carry out biomechanical tests of long bones loaded in torsion to failure. A device was fabricated to perform torsional tests of long bones using a single-axis linear actuator. The principal operation of the device was to transform the vertical displacement of a material testing machine's linear actuator into rotational movement using a spur gear and rack system. Accuracy and precision of the device were quantified using cast-acrylic rods with known torque-rotation behavior. Cadaveric experimentation was used to replicate a clinically relevant spiral fracture in eleven human proximal tibiae; strain-gage data were recorded for a single specimen. The device had an experimental error of less than 0.2 Nm and was repeatable to within 0.3%. Strain gage data were in line with those expected from pure torsion and the cadaveric tibiae illustrated spiral fractures at ultimate torque and rotation values of 130.6 +/- 53.2 Nm and 8.3 +/- 1.5 degrees, respectively. Ultimate torque was highly correlated with DXA assessed bone mineral density (r = 0.87; p < 0.00 1). The device presented is applicable to any torsional testing of long bone when only a single-axis linear actuator is available. PMID:23025174

  8. Do grain boundaries in nanophase metals slide?

    SciTech Connect

    Bringa, E M; Leveugle, E; Caro, A

    2006-10-27

    Nanophase metallic materials show a maximum in strength as grain size decreases to the nano scale, indicating a break down of the Hall-Petch relation. Grain boundary sliding, as a possible accommodation mechanisms, is often the picture that explain computer simulations results and real experiments. In a recent paper, Bringa et al. Science 309, 1838 (2005), we report on the observation of an ultra-hard behavior in nanophase Cu under shock loading, explained in terms of a reduction of grain boundary sliding under the influence of the shock pressure. In this work we perform a detailed study of the effects of hydrostatic pressure on nanophase Cu plasticity and find that it can be understood in terms of pressure dependent grain boundary sliding controlled by a Mohr-Coulomb law.

  9. 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.

  10. Experimental Testing of Glacier Sliding Laws

    NASA Astrophysics Data System (ADS)

    Zoet, L.; Iverson, N. R.

    2013-12-01

    Glacier sliding laws exist in various forms and are applied in modeling of glacier dynamics. Sliding laws have been, in most cases, theoretically derived but not experimentally tested. Under certain conditions ice sliding over a rigid bed will generate cavities in the lees of bedrock bumps. These cavities will redistribute shear stress to regions of the bed that are in contact with ice. Sliding laws that incorporate cavity formation relate drag to the maximum adverse slope of the region of ice-bed contact. Sinusoidal and stepped-bed geometries are, therefore, predicted to affect basal drag differently. A sinusoidal bed is predicted to have a double-valued drag response as a function of sliding velocity, whereas the steady-state drag on a stepped bed with linear adverse slopes is expected to be independent of sliding velocity. We have conducted an experimental study of sliding laws using a ring shear apparatus that slides ice over a rigid bed. The device rotates a ring of ice that is 20 cm wide, 20 cm tall, with outer diameter of 90 cm. The sliding speed at the ice ring's centerline was incrementally stepped between 7.25--324 m/yr, and a vertical stress of 500 kPa was applied to the ice ring. The ice consisted initially of randomly oriented crystals that with sliding quickly developed a fabric like those observed in ice near glacier beds. The temperature of the ice is held at the pressure melting point and is regulated to ~0.01oC by a bath of circulating fluid that surrounds the sample chamber. Experiments have been conducted on a stepped bed with a constant slope of 8.3 and a sinusoidal bed with a wavelength of 183.3 mm and an amplitude of 15.3 mm. Water was allowed to drain from cavities, so effective stress at the bed was equal to the total vertical stress. Our experimental results differ from theoretical predictions. For the stepped bed, a decrease in shear stress of ~50% over a 12-fold increase in velocity is observed, in contrast to theoretical predictions of

  11. 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.

  12. Phototransduction in mouse rods and cones

    PubMed Central

    Fu, Yingbin; Yau, King-Wai

    2010-01-01

    Phototransduction is the process by which light triggers an electrical signal in a photoreceptor cell. Image-forming vision in vertebrates is mediated by two types of photoreceptors: the rods and the cones. In this review, we provide a summary of the success in which the mouse has served as a vertebrate model for studying rod phototransduction, with respect to both the activation and termination steps. Cones are still not as well-understood as rods partly because it is difficult to work with mouse cones due to their scarcity and fragility. The situation may change, however. PMID:17226052

  13. 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

  14. 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.

  15. 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.

  16. Control rod drive hydraulic system

    DOEpatents

    Ose, Richard A.

    1992-01-01

    A hydraulic system for a control rod drive (CRD) includes a variable output-pressure CR pump operable in a charging mode for providing pressurized fluid at a charging pressure, and in a normal mode for providing the pressurized fluid at a purge pressure, less than the charging pressure. Charging and purge lines are disposed in parallel flow between the CRD pump and the CRD. A hydraulic control unit is disposed in flow communication in the charging line and includes a scram accumulator. An isolation valve is provided in the charging line between the CRD pump and the scram accumulator. A controller is operatively connected to the CRD pump and the isolation valve and is effective for opening the isolation valve and operating the CRD pump in a charging mode for charging the scram accumulator, and closing the isolation valve and operating the CRD pump in a normal mode for providing to the CRD through the purge line the pressurized fluid at a purge pressure lower than the charging pressure.

  17. Position and torque tracking: series elastic actuation versus model-based-controlled hydraulic actuation.

    PubMed

    Otten, Alexander; van Vuuren, Wieke; Stienen, Arno; van Asseldonk, Edwin; Schouten, Alfred; van der Kooij, Herman

    2011-01-01

    Robotics used for diagnostic measurements on, e.g. stroke survivors, require actuators that are both stiff and compliant. Stiffness is required for identification purposes, and compliance to compensate for the robots dynamics, so that the subject can move freely while using the robot. A hydraulic actuator can act as a position (stiff) or a torque (compliant) actuator. The drawback of a hydraulic actuator is that it behaves nonlinear. This article examines two methods for controlling a nonlinear hydraulic actuator. The first method that is often applied uses an elastic element (i.e. spring) connected in series with the hydraulic actuator so that the torque can be measured as the deflection of the spring. This torque measurement is used for proportional integral control. The second method of control uses the inverse of the model of the actuator as a linearizing controller. Both methods are compared using simulation results. The controller designed for the series elastic hydraulic actuator is faster to implement, but only shows good performance for the working range for which the controller is designed due to the systems nonlinear behavior. The elastic element is a limiting factor when designing a position controller due to its low torsional stiffness. The model-based controller linearizes the nonlinear system and shows good performance when used for torque and position control. Implementing the model-based controller does require building and validating of the detailed model. PMID:22275654

  18. Optoelectrowetting for continuous microdroplet actuation

    NASA Astrophysics Data System (ADS)

    Collier, Christopher M.; Hill, Kyle A.; DeWachter, Mark A.; Huizing, Alex M.; Holzman, Jonathan F.

    2014-05-01

    Microfluidics technologies have received great attention and appear in many bioanalyses applications. A recent microfluidics subset has appeared as droplet-based digital microfluidics (DMF). Here, microdroplets are manipulated in a two-dimensional on-chip plane using electric fields, contrasting the one-dimensional pressure-based channel flow of continuous flow microfluidics. These DMF systems fundamentally offer reconfigurability, whereby one device performs many bioanalysis tasks. A subset of DMF systems called optoelectrowetting is also of recent interest due to its ability for intricate microdroplet routing processes in the on-chip plane. For an optoelectrowetting chip, the DMF structure is modified with optically triggered electrodes with arrayed photoconductive switches. The arrayed photoconductive switches are optically-activated so microdroplets in the vicinity are routed to the illuminated switch. Unfortunately, such systems still require intricate electrode arrays, limiting microdroplet actuation resolution by the electrode size. This work proposes an on-chip optofluidic device with a continuous and planar semiconductor layer as the photoconductive mechanism. An illuminated section of the semiconductor layer acts as a localized electrode, with the photogenerated charge-carriers attracting nearby microdroplets. Given this planar topology, the illuminating beam is used to move the microdroplets continuously over the on-chip plane with precise optical control. The resolution for such a process is ultimately limited by charge-carrier diffusion, so an alternative material, a nanocomposite, is introduced to the on-chip device design. The nanocomposite consists of 20 nm semiconductor nanoparticles embedded in an insulative polymer host. This gives restricted diffusion length, being on the nanometer-scale of the nanoparticle diameter. Experimental device operation is demonstrated.

  19. Design of an innovative magnetostrictive patch actuator

    NASA Astrophysics Data System (ADS)

    Cinquemani, S.; Giberti, H.

    2015-04-01

    Magnetostrictive actuators can be profitably used to reduce vibration in structures. However, this technology has been exploited only to develop inertial actuators, while patches actuators have not been ever used in practice. Patches actuators consist on a layer of magnetostrictive material, which has to be stuck to the surface of the vibrating structure, and on a coil surrounding the layer itself. However, the presence of the winding severely limits the use of such devices. As a matter of fact, the scientific literature reports only theoretical uses of such actuators, but, in practice it does not seem they were ever used. This paper presents an innovative solution to improve the structure of the actuator patches, allowing their use in several practical applications. The principle of operation of these devices is rather simple. The actuator patch is able to generate a local deformation of the surface of the vibrating structure so as to introduce an equivalent damping that dissipates the kinetic energy associated to the vibration. This deformation is related to the behavior of the magnetostrictive material immersed in a variable magnetic field generated by the a variable current flowing in the winding. Contrary to what suggested in the theoretical literature, the designed device has the advantage of generating the variable magnetic field no longer in close proximity of the material, but in a different area, thus allowing a better coupling. The magnetic field is then conveyed through a suitable ferromagnetic structure to the magnetostrictive material. The device has been designed and simulated through FEA. Results confirm that the new configuration can easily overcome all the limits of traditional devices.

  20. Position Sensor Integral with a Linear Actuator

    NASA Technical Reports Server (NTRS)

    Howard, David E.; Alhorn, Dean C.

    2004-01-01

    A noncontact position sensor has been designed for use with a specific two-dimensional linear electromagnetic actuator. To minimize the bulk and weight added by the sensor, the sensor has been made an integral part of the actuator: that is to say, parts of the actuator structure and circuitry are used for sensing as well as for varying position. The actuator (see Figure 1) includes a C-shaped permanent magnet and an armature that is approximately centered in the magnet gap. The intended function of the actuator is to cause the permanent magnet to translate to, and/or remain at, commanded x and y coordinates, relative to the armature. In addition, some incidental relative motion along the z axis is tolerated but not controlled. The sensor is required to measure the x and y displacements from a nominal central position and to be relatively insensitive to z displacement. The armature contains two sets of electromagnet windings oriented perpendicularly to each other and electrically excited in such a manner as to generate forces in the x,y plane to produce the required motion. Small sensor excitation coils are mounted on the pole tips of the permanent magnet. These coils are excited with a sine wave at a frequency of 20 kHz. This excitation is transformer-coupled to the armature windings. The geometric arrangement of the excitation coils and armature windings is such that the amplitudes of the 20-kHz voltages induced in the armature windings vary nearly linearly with x and y displacements and do not vary significantly with small z displacements. Because the frequency of 20 kHz is much greater than the maximum frequency characteristic of the actuation signals applied to the armature windings, there is no appreciable interference between actuator and sensor functions of the armature windings.