Design and development of a bio-inspired, under-actuated soft gripper.

PubMed

Hassan, Taimoor; Manti, Mariangela; Passetti, Giovanni; d'Elia, Nicolò; Cianchetti, Matteo; Laschi, Cecilia

2015-08-01

The development of robotic devices able to perform manipulation tasks mimicking the human hand has been assessed on large scale. This work stands in the challenging scenario where soft materials are combined with bio-inspired design in order to develop soft grippers with improved grasping and holding capabilities. We are going to show a low-cost, under-actuated and adaptable soft gripper, highlighting the design and the manufacturing process. In particular, a critical analysis is made among three versions of the gripper with same design and actuation mechanism, but based on different materials. A novel actuation principle has been implemented in both cases, in order to reduce the encumbrance of the entire system and improve its aesthetics. Grasping and holding capabilities have been tested for each device, with target objects varying in shape, size and material. Results highlight synergy between the geometry and the intrinsic properties of the soft material, showing the way to novel design principles for soft grippers.

A novel anti-windup framework for cascade control systems: an application to underactuated mechanical systems.

PubMed

Mehdi, Niaz; Rehan, Muhammad; Malik, Fahad Mumtaz; Bhatti, Aamer Iqbal; Tufail, Muhammad

2014-05-01

This paper describes the anti-windup compensator (AWC) design methodologies for stable and unstable cascade plants with cascade controllers facing actuator saturation. Two novel full-order decoupling AWC architectures, based on equivalence of the overall closed-loop system, are developed to deal with windup effects. The decoupled architectures have been developed, to formulate the AWC synthesis problem, by assuring equivalence of the coupled and the decoupled architectures, instead of using an analogy, for cascade control systems. A comparison of both AWC architectures from application point of view is provided to consolidate their utilities. Mainly, one of the architecture is better in terms of computational complexity for implementation, while the other is suitable for unstable cascade systems. On the basis of the architectures for cascade systems facing stability and performance degradation problems in the event of actuator saturation, the global AWC design methodologies utilizing linear matrix inequalities (LMIs) are developed. These LMIs are synthesized by application of the Lyapunov theory, the global sector condition and the ℒ2 gain reduction of the uncertain decoupled nonlinear component of the decoupled architecture. Further, an LMI-based local AWC design methodology is derived by utilizing a local sector condition by means of a quadratic Lyapunov function to resolve the windup problem for unstable cascade plants under saturation. To demonstrate effectiveness of the proposed AWC schemes, an underactuated mechanical system, the ball-and-beam system, is considered, and details of the simulation and practical implementation results are described. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Hydrodynamics of an Under-actuated Plesiosaur-inspired robot

NASA Astrophysics Data System (ADS)

Weymouth, Gabriel; Devereux, Kate; Copsey, Nick; Muscutt, Luke; Downes, Jon; Ganapathisubramani, Bharath

2017-11-01

Underwater vehicles are increasingly important tools for use in science and engineering, but maneuverability and mission life seem to be mutually exclusive goals. Inspired by the unique swimming method of the plesiosaur, which used four flippers of essentially equal size and musculature, we analyzed designed and built an underwater vehicle with the potential for both gliding and active maneuvering modes. Using 2D simulations and strip theory approximation to account for the changing arc length along the flipper span, we studied the wake and forces on the foils and determined the optimum flipper geometry, spacing and kinematics. To reduce mechanical and control complexity and cost, we next studied the impact of under-actuated kinematics. Even after optimizing pivot location and range of motion, leaving the foils free to pitch was found to reduce efficiency by approximately 50%. Based on these specifications, the vehicle was built and tested over a range of free swimming and maneuvering cases using motion tracking equipment. The excellent maneuverability of the under-actuated vehicle validates the concept, and the new platform should enable further detailed experimental measurements in the future.

Development of an Underactuated 2-DOF Wrist Joint using McKibben PAMs

NASA Astrophysics Data System (ADS)

Rajagopal, S. P.; Jain, S.; Ramasubramanian, S. N.; Johnson, B. V.; Dwivedy, S. K.

2014-10-01

In this work, model of an underactuated 2-DOF wrist joint with pneumatically actuated muscles is proposed. For the joint, McKibben-type artificial muscles are used in parallel configuration for the actuation. For each Degree of Freedom (DOF) one agonist-antagonist pair arrangement is usually used with a pulley mechanism. A mathematical model of wrist joint is derived using conventional forward kinematic analysis. The static model relating pressure in the muscle with the orientation of the wrist joint is obtained by combining the experimental data and mathematical model. Regulation of pressure can be achieved by pulse width modulation control of on/off solenoid valves. A set of free vibration experiments are done for the dynamic identification of the muscle characteristics.

Partial feedback linearization control for 3-D underactuated overhead crane systems.

PubMed

Wu, Xianqing; He, Xiongxiong

2016-11-01

In this paper, a novel anti-swing control method is proposed for 3-dimensional (3-D) underactuated overhead crane systems, which guarantees fast transportation and efficient swing suppression. Specifically, to increase the performance of the payload swing suppression, a swing-suppressing element is introduced, based on which a novel positioning error signal is constructed. Then, a new control method is developed, and the overall system is divided into two subsystems. The stability analysis of the two subsystems and the overall system is given. In addition, the convergence of the system states is proved. Simulation results are provided to demonstrate the superior performance of the proposed controller over the existing controllers. Meanwhile, the practical performance of the proposed controller is experimentally validated on a portable overhead crane test-bed. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

The motion and control of a complex three-body space tethered system

NASA Astrophysics Data System (ADS)

Shi, Gefei; Zhu, Zhanxia; Chen, Shiyu; Yuan, Jianping; Tang, Biwei

2017-11-01

This paper is mainly devoted to investigating the dynamics and stability control of a three body-tethered satellite system which contains a main satellite and two subsatellites connected by two straight, massless and inextensible tethers. Firstly, a detailed mathematical model is established in the central gravitational field. Then, the dynamic characteristics of the established system are investigated and analyzed. Based on the dynamic analysis, a novel sliding mode prediction model (SMPM) control strategy is proposed to suppress the motion of the built tethered system. The numerical results show that the proposed underactuated control law is highly effective in suppressing the attitude/libration motion of the underactuated three-body tethered system. Furthermore, cases of different target angles are also examined and analyzed. The simulation results reveal that even if the final equilibrium states differ from different selections of the target angles, the whole system can still be maintained in acceptable areas.

Integral backstepping sliding mode control for underactuated systems: swing-up and stabilization of the Cart-Pendulum System.

PubMed

Adhikary, Nabanita; Mahanta, Chitralekha

2013-11-01

In this paper an integral backstepping sliding mode controller is proposed for controlling underactuated systems. A feedback control law is designed based on backstepping algorithm and a sliding surface is introduced in the final stage of the algorithm. The backstepping algorithm makes the controller immune to matched and mismatched uncertainties and the sliding mode control provides robustness. The proposed controller ensures asymptotic stability. The effectiveness of the proposed controller is compared against a coupled sliding mode controller for swing-up and stabilization of the Cart-Pendulum System. Simulation results show that the proposed integral backstepping sliding mode controller is able to reject both matched and mismatched uncertainties with a chattering free control law, while utilizing less control effort than the sliding mode controller. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

Robust adaptive antiswing control of underactuated crane systems with two parallel payloads and rail length constraint.

PubMed

Zhang, Zhongcai; Wu, Yuqiang; Huang, Jinming

2016-11-01

The antiswing control and accurate positioning are simultaneously investigated for underactuated crane systems in the presence of two parallel payloads on the trolley and rail length limitation. The equations of motion for the crane system in question are established via the Euler-Lagrange equation. An adaptive control strategy is proposed with the help of system energy function and energy shaping technique. Stability analysis shows that under the designed adaptive controller, the payload swings can be suppressed ultimately and the trolley can be regulated to the destination while not exceeding the pre-specified boundaries. Simulation results are provided to show the satisfactory control performances of the presented control method in terms of working efficiency as well as robustness with respect to external disturbances. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Trajectory tracking control for underactuated stratospheric airship

NASA Astrophysics Data System (ADS)

Zheng, Zewei; Huo, Wei; Wu, Zhe

2012-10-01

Stratospheric airship is a new kind of aerospace system which has attracted worldwide developing interests for its broad application prospects. Based on the trajectory linearization control (TLC) theory, a novel trajectory tracking control method for an underactuated stratospheric airship is presented in this paper. Firstly, the TLC theory is described sketchily, and the dynamic model of the stratospheric airship is introduced with kinematics and dynamics equations. Then, the trajectory tracking control strategy is deduced in detail. The designed control system possesses a cascaded structure which consists of desired attitude calculation, position control loop and attitude control loop. Two sub-loops are designed for the position and attitude control loops, respectively, including the kinematics control loop and dynamics control loop. Stability analysis shows that the controlled closed-loop system is exponentially stable. Finally, simulation results for the stratospheric airship to track typical trajectories are illustrated to verify effectiveness of the proposed approach.

Underactuated Spacecraft Control with Disturbance Compensation

DTIC Science & Technology

2015-08-31

fuel, which shortens the spacecraft’s life. Hence with RW failures, the spacecraft becomes underactuated. Recent missions, such as Kepler and...R. Cowen, "The wheels come off Kepler ," URL: http://www.nature.com/news/ the-wheels- come-off- kepler -1.13032 [cited 18 October 2013]. [2] Moos

Compact and low-cost humanoid hand powered by nylon artificial muscles.

PubMed

Wu, Lianjun; Jung de Andrade, Monica; Saharan, Lokesh Kumar; Rome, Richard Steven; Baughman, Ray H; Tadesse, Yonas

2017-02-03

This paper focuses on design, fabrication and characterization of a biomimetic, compact, low-cost and lightweight 3D printed humanoid hand (TCP Hand) that is actuated by twisted and coiled polymeric (TCP) artificial muscles. The TCP muscles were recently introduced and provided unprecedented strain, mechanical work, and lifecycle (Haines et al 2014 Science 343 868-72). The five-fingered humanoid hand is under-actuated and has 16 degrees of freedom (DOF) in total (15 for fingers and 1 at the palm). In the under-actuated hand designs, a single actuator provides coupled motions at the phalanges of each finger. Two different designs are presented along with the essential elements consisting of actuators, springs, tendons and guide systems. Experiments were conducted to investigate the performance of the TCP muscles in response to the power input (power magnitude, type of wave form such as pulsed or square wave, and pulse duration) and the resulting actuation stroke and force generation. A kinematic model of the flexor tendons was developed to simulate the flexion motion and compare with experimental results. For fast finger movements, short high-power pulses were employed. Finally, we demonstrated the grasping of various objects using the humanoid TCP hand showing an array of functions similar to a natural hand.

Hybrid switched time-optimal control of underactuated spacecraft

NASA Astrophysics Data System (ADS)

Olivares, Alberto; Staffetti, Ernesto

2018-04-01

This paper studies the time-optimal control problem for an underactuated rigid spacecraft equipped with both reaction wheels and gas jet thrusters that generate control torques about two of the principal axes of the spacecraft. Since a spacecraft equipped with two reaction wheels is not controllable, whereas a spacecraft equipped with two gas jet thrusters is controllable, this mixed actuation ensures controllability in the case in which one of the control axes is unactuated. A novel control logic is proposed for this hybrid actuation in which the reaction wheels are the main actuators and the gas jet thrusters act only after saturation or anticipating future saturation of the reaction wheels. The presence of both reaction wheels and gas jet thrusters gives rise to two operating modes for each actuated axis and therefore the spacecraft can be regarded as a switched dynamical system. The time-optimal control problem for this system is reformulated using the so-called embedding technique and the resulting problem is a classical optimal control problem. The main advantages of this technique are that integer or binary variables do not have to be introduced to model switching decisions between modes and that assumptions about the number of switches are not necessary. It is shown in this paper that this general method for the solution of optimal control problems for switched dynamical systems can efficiently deal with time-optimal control of an underactuated rigid spacecraft in which bound constraints on the torque of the actuators and on the angular momentum of the reaction wheels are taken into account.

Orthotic Body-Weight Support Through Underactuated Potential Energy Shaping with Contact Constraints

PubMed Central

Lv, Ge; Gregg, Robert D.

2015-01-01

Body-weight support is an effective clinical tool for gait rehabilitation after neurological impairment. Body-weight supported training systems have been developed to help patients regain mobility and confidence during walking, but conventional systems constrain the patient's treatment in clinical environments. We propose that this challenge could be addressed by virtually providing patients with body-weight support through the actuators of a powered orthosis (or exoskeleton) utilizing potential energy shaping control. However, the changing contact conditions and degrees of underactuation encountered during human walking present significant challenges to consistently matching a desired potential energy for the human in closed loop. We therefore introduce a generalized matching condition for shaping Lagrangian systems with holonomic contact constraints. By satisfying this matching condition for four phases of gait, we derive control laws to achieve virtual body-weight support through a powered knee-ankle orthosis. We demonstrate beneficial effects of virtual body-weight support in simulations of a human-like biped model, indicating the potential clinical value of this proposed control approach. PMID:26900254

Torque Control of Underactuated Tendon-driven Robotic Fingers

NASA Technical Reports Server (NTRS)

Ihrke, Chris A. (Inventor); Wampler, Charles W. (Inventor); Abdallah, Muhammad E. (Inventor); Reiland, Matthew J. (Inventor); Diftler, Myron A. (Inventor); Bridgwater, Lyndon (Inventor); Platt, Robert (Inventor)

2013-01-01

A robotic system includes a robot having a total number of degrees of freedom (DOF) equal to at least n, an underactuated tendon-driven finger driven by n tendons and n DOF, the finger having at least two joints, being characterized by an asymmetrical joint radius in one embodiment. A controller is in communication with the robot, and controls actuation of the tendon-driven finger using force control. Operating the finger with force control on the tendons, rather than position control, eliminates the unconstrained slack-space that would have otherwise existed. The controller may utilize the asymmetrical joint radii to independently command joint torques. A method of controlling the finger includes commanding either independent or parameterized joint torques to the controller to actuate the fingers via force control on the tendons.

Position and attitude tracking control for a quadrotor UAV.

PubMed

Xiong, Jing-Jing; Zheng, En-Hui

2014-05-01

A synthesis control method is proposed to perform the position and attitude tracking control of the dynamical model of a small quadrotor unmanned aerial vehicle (UAV), where the dynamical model is underactuated, highly-coupled and nonlinear. Firstly, the dynamical model is divided into a fully actuated subsystem and an underactuated subsystem. Secondly, a controller of the fully actuated subsystem is designed through a novel robust terminal sliding mode control (TSMC) algorithm, which is utilized to guarantee all state variables converge to their desired values in short time, the convergence time is so small that the state variables are acted as time invariants in the underactuated subsystem, and, a controller of the underactuated subsystem is designed via sliding mode control (SMC), in addition, the stabilities of the subsystems are demonstrated by Lyapunov theory, respectively. Lastly, in order to demonstrate the robustness of the proposed control method, the aerodynamic forces and moments and air drag taken as external disturbances are taken into account, the obtained simulation results show that the synthesis control method has good performance in terms of position and attitude tracking when faced with external disturbances. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

A new formation control of multiple underactuated surface vessels

NASA Astrophysics Data System (ADS)

Xie, Wenjing; Ma, Baoli; Fernando, Tyrone; Iu, Herbert Ho-Ching

2018-05-01

This work investigates a new formation control problem of multiple underactuated surface vessels. The controller design is based on input-output linearisation technique, graph theory, consensus idea and some nonlinear tools. The proposed smooth time-varying distributed control law guarantees that the multiple underactuated surface vessels globally exponentially converge to some desired geometric shape, which is especially centred at the initial average position of vessels. Furthermore, the stability analysis of zero dynamics proves that the orientations of vessels tend to some constants that are dependent on the initial values of vessels, and the velocities and control inputs of the vessels decay to zero. All the results are obtained under the communication scenarios of static directed balanced graph with a spanning tree. Effectiveness of the proposed distributed control scheme is demonstrated using a simulation example.

Leader-follower formation control of underactuated surface vehicles based on sliding mode control and parameter estimation.

PubMed

Sun, Zhijian; Zhang, Guoqing; Lu, Yu; Zhang, Weidong

2018-01-01

This paper studies the leader-follower formation control of underactuated surface vehicles with model uncertainties and environmental disturbances. A parameter estimation and upper bound estimation based sliding mode control scheme is proposed to solve the problem of the unknown plant parameters and environmental disturbances. For each of these leader-follower formation systems, the dynamic equations of position and attitude are analyzed using coordinate transformation with the aid of the backstepping technique. All the variables are guaranteed to be uniformly ultimately bounded stable in the closed-loop system, which is proven by the distribution design Lyapunov function synthesis. The main advantages of this approach are that: first, parameter estimation based sliding mode control can enhance the robustness of the closed-loop system in presence of model uncertainties and environmental disturbances; second, a continuous function is developed to replace the signum function in the design of sliding mode scheme, which devotes to reduce the chattering of the control system. Finally, numerical simulations are given to demonstrate the effectiveness of the proposed method. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

An under-actuated origami gripper with adjustable stiffness joints for multiple grasp modes

NASA Astrophysics Data System (ADS)

Firouzeh, Amir; Paik, Jamie

2017-05-01

Under-actuated robots offer multiple degrees of freedom without much added complexity to the actuation and control. Utilizing adjustable stiffness joints in these robots allows us to control their stable configurations and their mode of interaction with the environment. In this paper, we present the design of tendon-driven robotic origami (robogami) joints with adjustable stiffness. The proposed designs allow us to place joints along any direction in the plane of the robot and in the normal direction to the plane. The layer-by-layer manufacturing of robogamis facilitates the design and manufacturing of robots with different arrangement of joints for different applications. We use thermally activated shape memory polymer to control the joint stiffness. The manufacturing of the polymer layer is compatible with the layer-by-layer manufacturing process of the robogamis which results in scalable and customizable robots. To demonstrate, we prototyped an under-actuated gripper with three fingers and only one input actuation. The grasp mode of the gripper is set by adjusting the configuration of the locked joints and modulating the stiffness of the active joints. We present a model to estimate the configuration and the contact forces of the gripper at different settings that will assist us in design and control of future generation of under-actuated robogamis.

Frequency-tuning input-shaped manifold-based switching control for underactuated space robot equipped with flexible appendages

NASA Astrophysics Data System (ADS)

Kojima, Hirohisa; Ieda, Shoko; Kasai, Shinya

2014-08-01

Underactuated control problems, such as the control of a space robot without actuators on the main body, have been widely investigated. However, few studies have examined attitude control problems of underactuated space robots equipped with a flexible appendage, such as solar panels. In order to suppress vibration in flexible appendages, a zero-vibration input-shaping technique was applied to the link motion of an underactuated planar space robot. However, because the vibrational frequency depends on the link angles, simple input-shaping control methods cannot sufficiently suppress the vibration. In this paper, the dependency of the vibrational frequency on the link angles is measured experimentally, and the time-delay interval of the input shaper is then tuned based on the frequency estimated from the link angles. The proposed control method is referred to as frequency-tuning input-shaped manifold-based switching control (frequency-tuning IS-MBSC). The experimental results reveal that frequency-tuning IS-MBSC is capable of controlling the link angles and the main body attitude to maintain the target angles and that the vibration suppression performance of the proposed frequency-tuning IS-MBSC is better than that of a non-tuning IS-MBSC, which does not take the frequency variation into consideration.

Modeling of R/C Servo Motor and Application to Underactuated Mechanical Systems

NASA Astrophysics Data System (ADS)

Ishikawa, Masato; Kitayoshi, Ryohei; Wada, Takashi; Maruta, Ichiro; Sugie, Toshiharu

An R/C servo motor is a compact package of a DC geard-motor associated with a position servo controller. They are widely used in small-sized robotics and mechatronics by virtue of their compactness, easiness-to-use and high/weight ratio. However, it is crucial to clarify their internal model (including the embedded position servo) in order to improve control performance of mechatronic systems using R/C servo motors, such as biped robots or underactuted sysyems. In this paper, we propose a simple and realistic internal model of the R/C servo motors including the embedded servo controller, and estimate their physical parameters using continuous-time system identification method. We also provide a model of reference-to-torque transfer function so that we can estimate the internal torque acting on the load.

Analysis and Experimentation of Control Strategies for Underactuated Spacecraft

DTIC Science & Technology

2009-09-01

control techniques that provide time -invariant global asymptotic stability of the fully actuated spacecraft system of equations. Although these control ...momentum wheel actuators in finite time under the restriction that the total angular momentum vector of the system is zero. This control methodology...can be stabilizable to an arbitrarily small region about the equilibrium of the system via time -invariant smooth state feedback control

Stabilization and synchronization for a mechanical system via adaptive sliding mode control.

PubMed

Song, Zhankui; Sun, Kaibiao; Ling, Shuai

2017-05-01

In this paper, we investigate the synchronization problem of chaotic centrifugal flywheel governor with parameters uncertainty and lumped disturbances. A slave centrifugal flywheel governor system is considered as an underactuated following-system which a control input is designed to follow a master centrifugal flywheel governor system. To tackle lumped disturbances and uncertainty parameters, a novel synchronization control law is developed by employing sliding mode control strategy and Nussbaum gain technique. Adaptation updating algorithms are derived in the sense of Lyapunov stability analysis such that the lumped disturbances can be suppressed and the adverse effect caused by uncertainty parameters can be compensated. In addition, the synchronization tracking-errors are proven to converge to a small neighborhood of the origin. Finally, simulation results demonstrate the effectiveness of the proposed control scheme. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

A close examination of under-actuated attitude control subsystem design for future satellite missions' life extension

NASA Astrophysics Data System (ADS)

Lam, Quang M.; Barkana, Itzhak

2014-12-01

Satellite mission life, maintained and prolonged beyond its typical norm of their expectancy, are primarily dictated by the state of health of its Reaction Wheel Assembly (RWA), especially for commercial GEO satellites since torquer bars are no longer applicable while thruster assistant is unacceptable due to pointing accuracy impact during jet firing. The RWA is the primary set of actuators (as compared to thrusters for orbit maintenance and maneuvering) mainly responsible for the satellite mission for accurately and precisely pointing its payloads to the right targets to conduct its mission operations. The RWA consisting of either a set of four in pyramid or three in orthogonal is the primary set of actuators to allow the satellite to achieve accurate and precise pointing of the satellite payloads towards the desired targets. Future space missions will be required to achieve much longer lives and are currently perceived by the GEO satellite community as an "expected norm" of 20 years or longer. Driven by customers' demands/goals and competitive market have challenged Attitude Control Subsystems (ACS) engineers to develop better ACS algorithms to address such an emerging need. There are two main directions to design satellite's under-actuated control subsystem: (1) Attitude Feedback with Zero Momentum Principle and (2) Attitude Control by Angular Velocity Tracking via Small Time Local Controllability concept. Successful applications of these control laws have been largely demonstrated via simulation for the rest to rest case. Limited accuracy and oscillatory behaviors are observed in three axes for non-zero wheel momentum while realistic loss of a wheel scenario (i.e., fully actuated to under-actuated) has not been closely examined! This study revisits the under-actuated control design with detailed set ups of multiple scenarios reflecting real life operating conditions which have put current under-actuated control laws mentioned earlier into a re-evaluation mode since rest to rest case is not adequate to truly represent an on orbit failure of a single wheel. The study is intended to facilitate the ACS community to further develop a more practical under-actuated control law and present a path to extend these current thinking to address a more realistic reconfigurable ACS subject to a dynamic transition from a 3 RWs mode to 2 RWs mode.

Neural network-based optimal adaptive output feedback control of a helicopter UAV.

PubMed

Nodland, David; Zargarzadeh, Hassan; Jagannathan, Sarangapani

2013-07-01

Helicopter unmanned aerial vehicles (UAVs) are widely used for both military and civilian operations. Because the helicopter UAVs are underactuated nonlinear mechanical systems, high-performance controller design for them presents a challenge. This paper introduces an optimal controller design via an output feedback for trajectory tracking of a helicopter UAV, using a neural network (NN). The output-feedback control system utilizes the backstepping methodology, employing kinematic and dynamic controllers and an NN observer. The online approximator-based dynamic controller learns the infinite-horizon Hamilton-Jacobi-Bellman equation in continuous time and calculates the corresponding optimal control input by minimizing a cost function, forward-in-time, without using the value and policy iterations. Optimal tracking is accomplished by using a single NN utilized for the cost function approximation. The overall closed-loop system stability is demonstrated using Lyapunov analysis. Finally, simulation results are provided to demonstrate the effectiveness of the proposed control design for trajectory tracking.

Active-passive vibration absorber of beam-cart-seesaw system with piezoelectric transducers

NASA Astrophysics Data System (ADS)

Lin, J.; Huang, C. J.; Chang, Julian; Wang, S.-W.

2010-09-01

In contrast with fully controllable systems, a super articulated mechanical system (SAMS) is a controlled underactuated mechanical system in which the dimensions of the configuration space exceed the dimensions of the control input space. The objectives of the research are to develop a novel SAMS model which is called beam-cart-seesaw system, and renovate a novel approach for achieving a high performance active-passive piezoelectric vibration absorber for such system. The system consists of two mobile carts, which are coupled via rack and pinion mechanics to two parallel tracks mounted on pneumatic rodless cylinders. One cart carries an elastic beam, and the other cart acts as a counterbalance. One adjustable counterweight mass is also installed underneath the seesaw to serve as a passive damping mechanism to absorb impact and shock energy. The motion and control of a Bernoulli-Euler beam subjected to the modified cart/seesaw system are analyzed first. Moreover, gray relational grade is utilized to investigate the sensitivity of tuning the active proportional-integral-derivative (PID) controller to achieve desired vibration suppression performance. Consequently, it is shown that the active-passive vibration absorber can not only provide passive damping, but can also enhance the active action authority. The proposed software/hardware platform can also be profitable for the standardization of laboratory equipment, as well as for the development of entertainment tools.

Wake topology of under-actuated rajiform batoid robots

NASA Astrophysics Data System (ADS)

Valdivia Y Alvarado, Pablo; Weymouth, Gabriel; Thekoodan, Dilip; Patrikalakis, Nicholas

2011-11-01

Under-actuated continuous soft robots are designed to have modes of vibration that match desired body motions using minimal actuation. The desired modes of vibration are enabled by flexible continuous bodies with heterogenous material distributions. Errors or intentional approximations in the manufactured material distributions alter the achieved body motions and influence the resulting locomotion performance. An under-actuated continuous soft robot designed to mimic rajiform batoids such as stingrays is used to investigate the influence that fin kinematics variations have on wake topology, and the trade-offs that simplifying the body material structure has on achievable swimming performance. Pectoral fin kinematics in rajiform batoids are defined by traveling waves along the fin cord with particular amplitude envelopes along both the fin cord and span. Digital particle image velocimetry (DPIV) analysis of a prototype's wake structure and immersed-boundary numerical simulations are used to clarify the role of traveling wave wavelength, fin flapping frequency, and amplitude envelope characteristics on the resulting wake topology and swimming performance.

Optimal reorientation of asymmetric underactuated spacecraft using differential flatness and receding horizon control

NASA Astrophysics Data System (ADS)

Cai, Wei-wei; Yang, Le-ping; Zhu, Yan-wei

2015-01-01

This paper presents a novel method integrating nominal trajectory optimization and tracking for the reorientation control of an underactuated spacecraft with only two available control torque inputs. By employing a pseudo input along the uncontrolled axis, the flatness property of a general underactuated spacecraft is extended explicitly, by which the reorientation trajectory optimization problem is formulated into the flat output space with all the differential constraints eliminated. Ultimately, the flat output optimization problem is transformed into a nonlinear programming problem via the Chebyshev pseudospectral method, which is improved by the conformal map and barycentric rational interpolation techniques to overcome the side effects of the differential matrix's ill-conditions on numerical accuracy. Treating the trajectory tracking control as a state regulation problem, we develop a robust closed-loop tracking control law using the receding-horizon control method, and compute the feedback control at each control cycle rapidly via the differential transformation method. Numerical simulation results show that the proposed control scheme is feasible and effective for the reorientation maneuver.

An energy-optimal solution for transportation control of cranes with double pendulum dynamics: Design and experiments

NASA Astrophysics Data System (ADS)

Sun, Ning; Wu, Yiming; Chen, He; Fang, Yongchun

2018-03-01

Underactuated cranes play an important role in modern industry. Specifically, in most situations of practical applications, crane systems exhibit significant double pendulum characteristics, which makes the control problem quite challenging. Moreover, most existing planners/controllers obtained with standard methods/techniques for double pendulum cranes cannot minimize the energy consumption when fulfilling the transportation tasks. Therefore, from a practical perspective, this paper proposes an energy-optimal solution for transportation control of double pendulum cranes. By applying the presented approach, the transportation objective, including fast trolley positioning and swing elimination, is achieved with minimized energy consumption, and the residual oscillations are suppressed effectively with all the state constrains being satisfied during the entire transportation process. As far as we know, this is the first energy-optimal solution for transportation control of underactuated double pendulum cranes with various state and control constraints. Hardware experimental results are included to verify the effectiveness of the proposed approach, whose superior performance is reflected by being experimentally compared with some comparative controllers.

Principal components analysis based control of a multi-DoF underactuated prosthetic hand.

PubMed

Matrone, Giulia C; Cipriani, Christian; Secco, Emanuele L; Magenes, Giovanni; Carrozza, Maria Chiara

2010-04-23

Functionality, controllability and cosmetics are the key issues to be addressed in order to accomplish a successful functional substitution of the human hand by means of a prosthesis. Not only the prosthesis should duplicate the human hand in shape, functionality, sensorization, perception and sense of body-belonging, but it should also be controlled as the natural one, in the most intuitive and undemanding way. At present, prosthetic hands are controlled by means of non-invasive interfaces based on electromyography (EMG). Driving a multi degrees of freedom (DoF) hand for achieving hand dexterity implies to selectively modulate many different EMG signals in order to make each joint move independently, and this could require significant cognitive effort to the user. A Principal Components Analysis (PCA) based algorithm is used to drive a 16 DoFs underactuated prosthetic hand prototype (called CyberHand) with a two dimensional control input, in order to perform the three prehensile forms mostly used in Activities of Daily Living (ADLs). Such Principal Components set has been derived directly from the artificial hand by collecting its sensory data while performing 50 different grasps, and subsequently used for control. Trials have shown that two independent input signals can be successfully used to control the posture of a real robotic hand and that correct grasps (in terms of involved fingers, stability and posture) may be achieved. This work demonstrates the effectiveness of a bio-inspired system successfully conjugating the advantages of an underactuated, anthropomorphic hand with a PCA-based control strategy, and opens up promising possibilities for the development of an intuitively controllable hand prosthesis.

Intrinsic dynamics and total energy-shaping control of the ballbot system

NASA Astrophysics Data System (ADS)

Satici, A. C.; Donaire, A.; Siciliano, B.

2017-12-01

Research on bipedal locomotion has shown that a dynamic walking gait is energetically more efficient than a statically stable one. Analogously, even though statically stable multi-wheeled robots are easier to control, they are energetically less efficient and have low accelerations to avoid tipping over. In contrast, the ballbot is an underactuated, nonholonomically constrained mobile robot, whose upward equilibrium point has to be stabilised by active control. In this work, we derive coordinate-invariant, reduced, Euler-Poincaré equations of motion for the ballbot. By means of partial feedback linearisation, we obtain two independent passive outputs with corresponding storage functions and utilise these to come up with energy-shaping control laws which move the system along the trajectories of a new Lagrangian system whose desired equilibrium point is asymptotically stable by construction. The basin of attraction of this controller is shown to be almost global under certain conditions on the design of the mechanism which are reflected directly in the mass matrix of the unforced equations of motion.

An Analytical Dynamics Approach to the Control of Mechanical Systems

NASA Astrophysics Data System (ADS)

Mylapilli, Harshavardhan

A new and novel approach to the control of nonlinear mechanical systems is presented in this study. The approach is inspired by recent results in analytical dynamics that deal with the theory of constrained motion. The control requirements on the dynamical system are viewed from an analytical dynamics perspective and the theory of constrained motion is used to recast these control requirements as constraints on the dynamical system. Explicit closed form expressions for the generalized nonlinear control forces are obtained by using the fundamental equation of mechanics. The control so obtained is optimal at each instant of time and causes the constraints to be exactly satisfied. No linearizations and/or approximations of the nonlinear dynamical system are made, and no a priori structure is imposed on the nature of nonlinear controller. Three examples dealing with highly nonlinear complex dynamical systems that are chosen from diverse areas of discrete and continuum mechanics are presented to demonstrate the control approach. The first example deals with the energy control of underactuated inhomogeneous nonlinear lattices (or chains), the second example deals with the synchronization of the motion of multiple coupled slave gyros with that of a master gyro, and the final example deals with the control of incompressible hyperelastic rubber-like thin cantilever beams. Numerical simulations accompanying these examples show the ease, simplicity and the efficacy with which the control methodology can be applied and the accuracy with which the desired control objectives can be met.

Hardware Design and Testing of SUPERball, A Modular Tensegrity Robot

NASA Technical Reports Server (NTRS)

Sabelhaus, Andrew P.; Bruce, Jonathan; Caluwaerts, Ken; Chen, Yangxin; Lu, Dizhou; Liu, Yuejia; Agogino, Adrian K.; SunSpiral, Vytas; Agogino, Alice M.

2014-01-01

We are developing a system of modular, autonomous "tensegrity end-caps" to enable the rapid exploration of untethered tensegrity robot morphologies and functions. By adopting a self-contained modular approach, different end-caps with various capabilities (such as peak torques, or motor speeds), can be easily combined into new tensegrity robots composed of rods, cables, and actuators of different scale (such as in length, mass, peak loads, etc). As a first step in developing this concept, we are in the process of designing and testing the end-caps for SUPERball (Spherical Underactuated Planetary Exploration Robot), a project at the Dynamic Tensegrity Robotics Lab (DTRL) within NASA Ames's Intelligent Robotics Group. This work discusses the evolving design concepts and test results that have gone into the structural, mechanical, and sensing aspects of SUPERball. This representative tensegrity end-cap design supports robust and repeatable untethered mobility tests of the SUPERball, while providing high force, high displacement actuation, with a low-friction, compliant cabling system.

Robust leader-follower formation tracking control of multiple underactuated surface vessels

NASA Astrophysics Data System (ADS)

Peng, Zhou-hua; Wang, Dan; Lan, Wei-yao; Sun, Gang

2012-09-01

This paper is concerned with the formation control problem of multiple underactuated surface vessels moving in a leader-follower formation. The formation is achieved by the follower to track a virtual target defined relative to the leader. A robust adaptive target tracking law is proposed by using neural network and backstepping techniques. The advantage of the proposed control scheme is that the uncertain nonlinear dynamics caused by Coriolis/centripetal forces, nonlinear damping, unmodeled hydrodynamics and disturbances from the environment can be compensated by on line learning. Based on Lyapunov analysis, the proposed controller guarantees the tracking errors converge to a small neighborhood of the origin. Simulation results demonstrate the effectiveness of the control strategy.

Planning and Control for Microassembly of Structures Composed of Stress-Engineered MEMS Microrobots

PubMed Central

Donald, Bruce R.; Levey, Christopher G.; Paprotny, Igor; Rus, Daniela

2013-01-01

We present control strategies that implement planar microassembly using groups of stress-engineered MEMS microrobots (MicroStressBots) controlled through a single global control signal. The global control signal couples the motion of the devices, causing the system to be highly underactuated. In order for the robots to assemble into arbitrary planar shapes despite the high degree of underactuation, it is desirable that each robot be independently maneuverable (independently controllable). To achieve independent control, we fabricated robots that behave (move) differently from one another in response to the same global control signal. We harnessed this differentiation to develop assembly control strategies, where the assembly goal is a desired geometric shape that can be obtained by connecting the chassis of individual robots. We derived and experimentally tested assembly plans that command some of the robots to make progress toward the goal, while other robots are constrained to remain in small circular trajectories (closed-loop orbits) until it is their turn to move into the goal shape. Our control strategies were tested on systems of fabricated MicroStressBots. The robots are 240–280 μm × 60 μm × 7–20 μm in size and move simultaneously within a single operating environment. We demonstrated the feasibility of our control scheme by accurately assembling five different types of planar microstructures. PMID:23580796

Backstepping-based cooperative and adaptive tracking control design for a group of underactuated AUVs in horizontal plan

NASA Astrophysics Data System (ADS)

Ghommam, Jawhar; Saad, Maarouf

2014-05-01

In this paper, we investigate new implementable cooperative adaptive backstepping controllers for a group of underactuated autonomous vehicles that are communicating with their local neighbours to track a time-varying virtual leader of which the relative position may only be available to a portion of the team members. At the kinematic cooperative control level of the autonomous underwater vehicle, the virtual cooperative controller is basically designed on a proportional and derivative consensus algorithm presented in Ren (2010), which involves velocity information from local neighbours. In this paper, we propose a new design algorithm based on singular perturbation theory that precludes the use of the neighbours' velocity information in the cooperative design. At the dynamic cooperative control level, calculation of the partial derivatives of some stabilising functions which in turn will contain velocity information from the local neighbours is required. To facilitate the implementation of the cooperative controllers, we propose a command filter approach technique to avoid analytic differentiation of the virtual cooperative control laws. We show how Lyapunov-based techniques and graph theory can be combined together to yield a robust cooperative controller where the uncertain dynamics of the cooperating vehicles and the constraints on the communication topology which contains a directed spanning tree are explicitly taken into account. Simulation results with a dynamic model of underactuated autonomous underwater vehicles moving on the horizontal plane are presented and discussed.

Coordinated path following of multiple underacutated marine surface vehicles along one curve.

PubMed

Liu, Lu; Wang, Dan; Peng, Zhouhua

2016-09-01

This paper investigates the coordinated path following problem for a fleet of underactuated marine surface vehicles (MSVs) along one curve. The dedicated control design is divided into two tasks. One is to steer individual underactuated MSV to track the given spatial path, and the other is to force the vehicles dispersed on a parameterized path subject to the constraints of a communication network. Specifically, a robust individual path following controller is developed based on a line-of-sight (LOS) guidance law and a reduced-order extended state observer (ESO). The vehicle sideslip angle due to environmental disturbances can be exactly identified. Then, the vehicle coordination is achieved by a path variable containment approach, under which the path variables are evenly dispersed between two virtual leaders. Another reduced-order ESO is developed to identify the composite disturbance related to the speed of virtual leaders and neighboring vehicles. The proposed coordination design is distributed since the reference speed does not need to be known by all vehicles as a priori. The input-to-state stability of the closed-loop network system is established via cascade theory. Simulation results demonstrate the effectiveness of the proposed design method. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Design and control of five fingered under-actuated robotic hand

NASA Astrophysics Data System (ADS)

Sahoo, Biswojit; Parida, Pramod Kumar

2018-04-01

Now a day's research regarding humanoid robots and its application in different fields (industry, household, rehabilitation and exploratory) is going on entire the globe. Among which a challenging topic is to design a dexterous robotic hand which not only can perform as a hand of a robot but also can be used in re habilitation. The basic key concern is a dexterous robot hand which can be able to mimic the function of biological hand to perform different operations. This thesis work is regarding design and control of a under-actuated robotic hand consisting of four under actuated fingers (index finger, middle finger, little finger and ring finger ) , a thumb and a dexterous palm which can copy the motions and grasp type of human hand which having 21degrees of freedom instead of 25Degree Of Freedom.

Current-Sensitive Path Planning for an Underactuated Free-Floating Ocean Sensorweb

NASA Technical Reports Server (NTRS)

Dahl, Kristen P.; Thompson, David R.; McLaren, David; Chao, Yi; Chien, Steve

2011-01-01

This work investigates multi-agent path planning in strong, dynamic currents using thousands of highly under-actuated vehicles. We address the specific task of path planning for a global network of ocean-observing floats. These submersibles are typified by the Argo global network consisting of over 3000 sensor platforms. They can control their buoyancy to float at depth for data collection or rise to the surface for satellite communications. Currently, floats drift at a constant depth regardless of the local currents. However, accurate current forecasts have become available which present the possibility of intentionally controlling floats' motion by dynamically commanding them to linger at different depths. This project explores the use of these current predictions to direct float networks to some desired final formation or position. It presents multiple algorithms for such path optimization and demonstrates their advantage over the standard approach of constant-depth drifting.

Evolved to fail: Bacteria induce flagellar buckling to reorient

NASA Astrophysics Data System (ADS)

Son, Kwangmin; Guasto, Jeffrey S.; Stocker, Roman

2012-11-01

Many marine bacteria swim with a single helical flagellum connected to a rotary motor via a 100 nm long universal joint called the ``hook.'' While these bacteria have seemingly just one degree of freedom, allowing them to swim only back and forth, they in fact exhibit large angular reorientations mediated by off-axis ``flicks'' of their flagellum. High-speed video microscopy revealed the mechanism underpinning this turning behavior: the buckling of the hook during the exceedingly brief (10 ms) forward run that follows a reversal. Direct measurements of the hook's mechanical properties corroborated this result, as the hook's structural stability is governed by the Sperm number, which compares the compressive load from propulsion to the elastic restoring force of the hook. Upon decreasing the Sperm number below a critical value by reducing the swimming speed, the frequency of flicks diminishes sharply, consistent with the criticality of buckling. This elegant, under-actuated turning mechanism appears widespread among marine bacteria and may provide a novel design concept in micro-robotics.

Formation Control for Water-Jet USV Based on Bio-Inspired Method

NASA Astrophysics Data System (ADS)

Fu, Ming-yu; Wang, Duan-song; Wang, Cheng-long

2018-03-01

The formation control problem for underactuated unmanned surface vehicles (USVs) is addressed by a distributed strategy based on virtual leader strategy. The control system takes account of disturbance induced by external environment. With the coordinate transformation, the advantage of the proposed scheme is that the control point can be any point of the ship instead of the center of gravity. By introducing bio-inspired model, the formation control problem is addressed with backstepping method. This avoids complicated computation, simplifies the control law, and smoothes the input signals. The system uniform ultimate boundness is proven by Lyapunov stability theory with Young inequality. Simulation results are presented to verify the effectiveness and robust of the proposed controller.

Neural network-based motion control of an underactuated wheeled inverted pendulum model.

PubMed

Yang, Chenguang; Li, Zhijun; Cui, Rongxin; Xu, Bugong

2014-11-01

In this paper, automatic motion control is investigated for one of wheeled inverted pendulum (WIP) models, which have been widely applied for modeling of a large range of two wheeled modern vehicles. First, the underactuated WIP model is decomposed into a fully actuated second order subsystem Σa consisting of planar movement of vehicle forward and yaw angular motions, and a nonactuated first order subsystem Σb of pendulum motion. Due to the unknown dynamics of subsystem Σa and the universal approximation ability of neural network (NN), an adaptive NN scheme has been employed for motion control of subsystem Σa . The model reference approach has been used whereas the reference model is optimized by the finite time linear quadratic regulation technique. The pendulum motion in the passive subsystem Σb is indirectly controlled using the dynamic coupling with planar forward motion of subsystem Σa , such that satisfactory tracking of a set pendulum tilt angle can be guaranteed. Rigours theoretic analysis has been established, and simulation studies have been performed to demonstrate the developed method.

A novel algorithm for fast grasping of unknown objects using C-shape configuration

NASA Astrophysics Data System (ADS)

Lei, Qujiang; Chen, Guangming; Meijer, Jonathan; Wisse, Martijn

2018-02-01

Increasing grasping efficiency is very important for the robots to grasp unknown objects especially subjected to unfamiliar environments. To achieve this, a new algorithm is proposed based on the C-shape configuration. Specifically, the geometric model of the used under-actuated gripper is approximated as a C-shape. To obtain an appropriate graspable position, this C-shape configuration is applied to fit geometric model of an unknown object. The geometric model of unknown object is constructed by using a single-view partial point cloud. To examine the algorithm using simulations, a comparison of the commonly used motion planners is made. The motion planner with the highest number of solved runs, lowest computing time and the shortest path length is chosen to execute grasps found by this grasping algorithm. The simulation results demonstrate that excellent grasping efficiency is achieved by adopting our algorithm. To validate this algorithm, experiment tests are carried out using a UR5 robot arm and an under-actuated gripper. The experimental results show that steady grasping actions are obtained. Hence, this research provides a novel algorithm for fast grasping of unknown objects.

Time-optimal trajectory planning for underactuated spacecraft using a hybrid particle swarm optimization algorithm

NASA Astrophysics Data System (ADS)

Zhuang, Yufei; Huang, Haibin

2014-02-01

A hybrid algorithm combining particle swarm optimization (PSO) algorithm with the Legendre pseudospectral method (LPM) is proposed for solving time-optimal trajectory planning problem of underactuated spacecrafts. At the beginning phase of the searching process, an initialization generator is constructed by the PSO algorithm due to its strong global searching ability and robustness to random initial values, however, PSO algorithm has a disadvantage that its convergence rate around the global optimum is slow. Then, when the change in fitness function is smaller than a predefined value, the searching algorithm is switched to the LPM to accelerate the searching process. Thus, with the obtained solutions by the PSO algorithm as a set of proper initial guesses, the hybrid algorithm can find a global optimum more quickly and accurately. 200 Monte Carlo simulations results demonstrate that the proposed hybrid PSO-LPM algorithm has greater advantages in terms of global searching capability and convergence rate than both single PSO algorithm and LPM algorithm. Moreover, the PSO-LPM algorithm is also robust to random initial values.

A novel single thruster control strategy for spacecraft attitude stabilization

NASA Astrophysics Data System (ADS)

Godard; Kumar, Krishna Dev; Zou, An-Min

2013-05-01

Feasibility of achieving three axis attitude stabilization using a single thruster is explored in this paper. Torques are generated using a thruster orientation mechanism with which the thrust vector can be tilted on a two axis gimbal. A robust nonlinear control scheme is developed based on the nonlinear kinematic and dynamic equations of motion of a rigid body spacecraft in the presence of gravity gradient torque and external disturbances. The spacecraft, controlled using the proposed concept, constitutes an underactuated system (a system with fewer independent control inputs than degrees of freedom) with nonlinear dynamics. Moreover, using thruster gimbal angles as control inputs make the system non-affine (control terms appear nonlinearly in the state equation). This necessitates the control algorithms to be developed based on nonlinear control theory since linear control methods are not directly applicable. The stability conditions for the spacecraft attitude motion for robustness against uncertainties and disturbances are derived to establish the regions of asymptotic 3-axis attitude stabilization. Several numerical simulations are presented to demonstrate the efficacy of the proposed controller and validate the theoretical results. The control algorithm is shown to compensate for time-varying external disturbances including solar radiation pressure, aerodynamic forces, and magnetic disturbances; and uncertainties in the spacecraft inertia parameters. The numerical results also establish the robustness of the proposed control scheme to negate disturbances caused by orbit eccentricity.

Spatial curvilinear path following control of underactuated AUV with multiple uncertainties.

PubMed

Miao, Jianming; Wang, Shaoping; Zhao, Zhiping; Li, Yuan; Tomovic, Mileta M

2017-03-01

This paper investigates the problem of spatial curvilinear path following control of underactuated autonomous underwater vehicles (AUVs) with multiple uncertainties. Firstly, in order to design the appropriate controller, path following error dynamics model is constructed in a moving Serret-Frenet frame, and the five degrees of freedom (DOFs) dynamic model with multiple uncertainties is established. Secondly, the proposed control law is separated into kinematic controller and dynamic controller via back-stepping technique. In the case of kinematic controller, to overcome the drawback of dependence on the accurate vehicle model that are present in a number of path following control strategies described in the literature, the unknown side-slip angular velocity and attack angular velocity are treated as uncertainties. Whereas in the case of dynamic controller, the model parameters perturbations, unknown external environmental disturbances and the nonlinear hydrodynamic damping terms are treated as lumped uncertainties. Both kinematic and dynamic uncertainties are estimated and compensated by designed reduced-order linear extended state observes (LESOs). Thirdly, feedback linearization (FL) based control law is implemented for the control model using the estimates generated by reduced-order LESOs. For handling the problem of computational complexity inherent in the conventional back-stepping method, nonlinear tracking differentiators (NTDs) are applied to construct derivatives of the virtual control commands. Finally, the closed loop stability for the overall system is established. Simulation and comparative analysis demonstrate that the proposed controller exhibits enhanced performance in the presence of internal parameter variations, external unknown disturbances, unmodeled nonlinear damping terms, and measurement noises. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

System Design and Locomotion of Superball, an Untethered Tensegrity Robot

NASA Technical Reports Server (NTRS)

Sabelhaus, Andrew P.; Bruce, Jonathan; Caluwaerts, Ken; Manovi, Pavlo; Firoozi, Roya Fallah; Dobi, Sarah; Agogino, Alice M.; Sunspiral, Vytas

2015-01-01

The Spherical Underactuated Planetary Exploration Robot ball (SUPERball) is an ongoing project within NASA Ames Research Center's Intelligent Robotics Group and the Dynamic Tensegrity Robotics Lab (DTRL). The current SUPERball is the first full prototype of this tensegrity robot platform, eventually destined for space exploration missions. This work, building on prior published discussions of individual components, presents the fully-constructed robot. Various design improvements are discussed, as well as testing results of the sensors and actuators that illustrate system performance. Basic low-level motor position controls are implemented and validated against sensor data, which show SUPERball to be uniquely suited for highly dynamic state trajectory tracking. Finally, SUPERball is shown in a simple example of locomotion. This implementation of a basic motion primitive shows SUPERball in untethered control.

[Study on the center-driven multiple degrees of freedom upper limb rehabilitation training robot].

PubMed

Huang, Xiaohai; Yu, Hongliu; Wang, Jinchao; Dong, Qi; Zhang, Linling; Meng, Qiaoling; Li, Sujiao; Wang, Duojin

2018-03-01

With the aging of the society, the number of stroke patients has been increasing year by year. Compared with the traditional rehabilitation therapy, the application of upper limb rehabilitation robot has higher efficiency and better rehabilitation effect, and has become an important development direction in the field of rehabilitation. In view of the current development status and the deficiency of upper limb rehabilitation robot system, combined with the development trend of all kinds of products of the upper limb rehabilitation robot, this paper designed a center-driven upper limb rehabilitation training robot for cable transmission which can help the patients complete 6 degrees of freedom (3 are driven, 3 are underactuated) training. Combined the structure of robot with more joints rehabilitation training, the paper choosed a cubic polynomial trajectory planning method in the joint space planning to design two trajectories of eating and lifting arm. According to the trajectory equation, the movement trajectory of each joint of the robot was drawn in MATLAB. It laid a foundation for scientific and effective rehabilitation training. Finally, the experimental prototype is built, and the mechanical structure and design trajectories are verified.

Neural Network-Based Self-Tuning PID Control for Underwater Vehicles

PubMed Central

Hernández-Alvarado, Rodrigo; García-Valdovinos, Luis Govinda; Salgado-Jiménez, Tomás; Gómez-Espinosa, Alfonso; Fonseca-Navarro, Fernando

2016-01-01

For decades, PID (Proportional + Integral + Derivative)-like controllers have been successfully used in academia and industry for many kinds of plants. This is thanks to its simplicity and suitable performance in linear or linearized plants, and under certain conditions, in nonlinear ones. A number of PID controller gains tuning approaches have been proposed in the literature in the last decades; most of them off-line techniques. However, in those cases wherein plants are subject to continuous parametric changes or external disturbances, online gains tuning is a desirable choice. This is the case of modular underwater ROVs (Remotely Operated Vehicles) where parameters (weight, buoyancy, added mass, among others) change according to the tool it is fitted with. In practice, some amount of time is dedicated to tune the PID gains of a ROV. Once the best set of gains has been achieved the ROV is ready to work. However, when the vehicle changes its tool or it is subject to ocean currents, its performance deteriorates since the fixed set of gains is no longer valid for the new conditions. Thus, an online PID gains tuning algorithm should be implemented to overcome this problem. In this paper, an auto-tune PID-like controller based on Neural Networks (NN) is proposed. The NN plays the role of automatically estimating the suitable set of PID gains that achieves stability of the system. The NN adjusts online the controller gains that attain the smaller position tracking error. Simulation results are given considering an underactuated 6 DOF (degrees of freedom) underwater ROV. Real time experiments on an underactuated mini ROV are conducted to show the effectiveness of the proposed scheme. PMID:27608018

Neural Network-Based Self-Tuning PID Control for Underwater Vehicles.

PubMed

Hernández-Alvarado, Rodrigo; García-Valdovinos, Luis Govinda; Salgado-Jiménez, Tomás; Gómez-Espinosa, Alfonso; Fonseca-Navarro, Fernando

2016-09-05

For decades, PID (Proportional + Integral + Derivative)-like controllers have been successfully used in academia and industry for many kinds of plants. This is thanks to its simplicity and suitable performance in linear or linearized plants, and under certain conditions, in nonlinear ones. A number of PID controller gains tuning approaches have been proposed in the literature in the last decades; most of them off-line techniques. However, in those cases wherein plants are subject to continuous parametric changes or external disturbances, online gains tuning is a desirable choice. This is the case of modular underwater ROVs (Remotely Operated Vehicles) where parameters (weight, buoyancy, added mass, among others) change according to the tool it is fitted with. In practice, some amount of time is dedicated to tune the PID gains of a ROV. Once the best set of gains has been achieved the ROV is ready to work. However, when the vehicle changes its tool or it is subject to ocean currents, its performance deteriorates since the fixed set of gains is no longer valid for the new conditions. Thus, an online PID gains tuning algorithm should be implemented to overcome this problem. In this paper, an auto-tune PID-like controller based on Neural Networks (NN) is proposed. The NN plays the role of automatically estimating the suitable set of PID gains that achieves stability of the system. The NN adjusts online the controller gains that attain the smaller position tracking error. Simulation results are given considering an underactuated 6 DOF (degrees of freedom) underwater ROV. Real time experiments on an underactuated mini ROV are conducted to show the effectiveness of the proposed scheme.

Demonstrations of bio-inspired perching landing gear for UAVs

NASA Astrophysics Data System (ADS)

Tieu, Mindy; Michael, Duncan M.; Pflueger, Jeffery B.; Sethi, Manik S.; Shimazu, Kelli N.; Anthony, Tatiana M.; Lee, Christopher L.

2016-04-01

Results are presented which demonstrate the feasibility and performance of two concepts of biologically-inspired landing-gear systems that enable bird-sized, unmanned aerial vehicles (UAV's) to land, perch, and take-off from branchlike structures and/or ledges. The first concept follows the anatomy of birds that can grasp ahold of a branch and perch as tendons in their legs are tensioned. This design involves a gravity-activated, cable-driven, underactuated, graspingfoot mechanism. As the UAV lands, its weight collapses a four-bar linkage pulling a cable which curls two opposing, multi-segmented feet to grasp the landing target. Each foot is a single, compliant mechanism fabricated by simultaneouly 3D-printing a flexible thermo-plastic and a stiffer ABS plastic. The design is optimized to grasp structures over a range of shapes and sizes. Quasi-static and flight tests of this landing gear affixed to RC rotorcraft (24 cm to 550 cm in diameter) demonstrate that the aircraft can land, perch, and take-off from a tree branch, rectangular wood board, PVC pipe, metal hand rail, chair armrest, and in addition, a stone wall ledge. Stability tests show that perching is maintained under base and wind disturbances. The second design concept, inspired by roosting bats, is a two-material, 3D-printed hooking mechanism that enables the UAV to stably suspend itself from a wire or small-diameter branch. The design balances structural stiffness for support and flexibility for the perching process. A flight-test demonstrates the attaching and dis-engaging of a small, RC quadcopter from a suspended line.

The Hamiltonian and Lagrangian approaches to the dynamics of nonholonomic systems

NASA Astrophysics Data System (ADS)

Koon, Wang Sang; Marsden, Jerrold E.

1997-08-01

This paper compares the Hamiltonian approach to systems with nonholonomic constraints (see [31, 2, 4, 29] and references therein) with the Lagrangian approach (see [16, 27, 9]). There are many differences in the approaches and each has its own advantages; some structures have been discovered on one side and their analogues on the other side are interesting to clarify. For example, the momentum equation and the reconstruction equation were first found on the Lagrangian side and are useful for the control theory of these systems, while the failure of the reduced two-form to be closed (i.e., the failure of the Poisson bracket to satisfy the Jacobi identity) was first noticed on the Hamiltonian side. Clarifying the relation between these approaches is important for the future development of the control theory and stability and bifurcation theory for such systems. In addition to this work, we treat, in this unified framework, a simplified model of the bicycle (see [12, 13]), which is an important underactuated (nonminimum phase) control system.

Exploiting short-term memory in soft body dynamics as a computational resource

PubMed Central

Nakajima, K.; Li, T.; Hauser, H.; Pfeifer, R.

2014-01-01

Soft materials are not only highly deformable, but they also possess rich and diverse body dynamics. Soft body dynamics exhibit a variety of properties, including nonlinearity, elasticity and potentially infinitely many degrees of freedom. Here, we demonstrate that such soft body dynamics can be employed to conduct certain types of computation. Using body dynamics generated from a soft silicone arm, we show that they can be exploited to emulate functions that require memory and to embed robust closed-loop control into the arm. Our results suggest that soft body dynamics have a short-term memory and can serve as a computational resource. This finding paves the way towards exploiting passive body dynamics for control of a large class of underactuated systems. PMID:25185579

Decentralized Feedback Controllers for Robust Stabilization of Periodic Orbits of Hybrid Systems: Application to Bipedal Walking.

PubMed

Hamed, Kaveh Akbari; Gregg, Robert D

2017-07-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially and robustly stabilize periodic orbits for hybrid dynamical systems against possible uncertainties in discrete-time phases. The algorithm assumes a family of parameterized and decentralized nonlinear controllers to coordinate interconnected hybrid subsystems based on a common phasing variable. The exponential and [Formula: see text] robust stabilization problems of periodic orbits are translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities. By investigating the properties of the Poincaré map, some sufficient conditions for the convergence of the iterative algorithm are presented. The power of the algorithm is finally demonstrated through designing a set of robust stabilizing local nonlinear controllers for walking of an underactuated 3D autonomous bipedal robot with 9 degrees of freedom, impact model uncertainties, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg.

Decentralized Feedback Controllers for Robust Stabilization of Periodic Orbits of Hybrid Systems: Application to Bipedal Walking

PubMed Central

Hamed, Kaveh Akbari; Gregg, Robert D.

2016-01-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially and robustly stabilize periodic orbits for hybrid dynamical systems against possible uncertainties in discrete-time phases. The algorithm assumes a family of parameterized and decentralized nonlinear controllers to coordinate interconnected hybrid subsystems based on a common phasing variable. The exponential and H2 robust stabilization problems of periodic orbits are translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities. By investigating the properties of the Poincaré map, some sufficient conditions for the convergence of the iterative algorithm are presented. The power of the algorithm is finally demonstrated through designing a set of robust stabilizing local nonlinear controllers for walking of an underactuated 3D autonomous bipedal robot with 9 degrees of freedom, impact model uncertainties, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg. PMID:28959117

Arbitrary Symmetric Running Gait Generation for an Underactuated Biped Model.

PubMed

Dadashzadeh, Behnam; Esmaeili, Mohammad; Macnab, Chris

2017-01-01

This paper investigates generating symmetric trajectories for an underactuated biped during the stance phase of running. We use a point mass biped (PMB) model for gait analysis that consists of a prismatic force actuator on a massless leg. The significance of this model is its ability to generate more general and versatile running gaits than the spring-loaded inverted pendulum (SLIP) model, making it more suitable as a template for real robots. The algorithm plans the necessary leg actuator force to cause the robot center of mass to undergo arbitrary trajectories in stance with any arbitrary attack angle and velocity angle. The necessary actuator forces follow from the inverse kinematics and dynamics. Then these calculated forces become the control input to the dynamic model. We compare various center-of-mass trajectories, including a circular arc and polynomials of the degrees 2, 4 and 6. The cost of transport and maximum leg force are calculated for various attack angles and velocity angles. The results show that choosing the velocity angle as small as possible is beneficial, but the angle of attack has an optimum value. We also find a new result: there exist biped running gaits with double-hump ground reaction force profiles which result in less maximum leg force than single-hump profiles.

Arbitrary Symmetric Running Gait Generation for an Underactuated Biped Model

PubMed Central

Esmaeili, Mohammad; Macnab, Chris

2017-01-01

This paper investigates generating symmetric trajectories for an underactuated biped during the stance phase of running. We use a point mass biped (PMB) model for gait analysis that consists of a prismatic force actuator on a massless leg. The significance of this model is its ability to generate more general and versatile running gaits than the spring-loaded inverted pendulum (SLIP) model, making it more suitable as a template for real robots. The algorithm plans the necessary leg actuator force to cause the robot center of mass to undergo arbitrary trajectories in stance with any arbitrary attack angle and velocity angle. The necessary actuator forces follow from the inverse kinematics and dynamics. Then these calculated forces become the control input to the dynamic model. We compare various center-of-mass trajectories, including a circular arc and polynomials of the degrees 2, 4 and 6. The cost of transport and maximum leg force are calculated for various attack angles and velocity angles. The results show that choosing the velocity angle as small as possible is beneficial, but the angle of attack has an optimum value. We also find a new result: there exist biped running gaits with double-hump ground reaction force profiles which result in less maximum leg force than single-hump profiles. PMID:28118401

Controlling under-actuated robot arms using a high speed dynamics process

NASA Technical Reports Server (NTRS)

Jain, Abhinandan (Inventor); Rodriguez, Guillermo (Inventor)

1994-01-01

The invention controls an under-actuated manipulator by first obtaining predetermined active joint accelerations of the active joints and the passive joint friction forces of the passive joints, then computing articulated body qualities for each of the joints from the current positions of the links, and finally computing from the articulated body qualities and from the active joint accelerations and the passive joint forces, active joint forces of the active joints. Ultimately, the invention transmits servo commands to the active joint forces thus computed to the respective ones of the joint servos. The computation of the active joint forces is accomplished using a recursive dynamics algorithm. In this computation, an inward recursion is first carried out for each link, beginning with the outermost link in order to compute the residual link force of each link from the active joint acceleration if the corresponding joint is active, or from the known passive joint force if the corresponding joint is passive. Then, an outward recursion is carried out for each link in which the active joint force is computed from the residual link force if the corresponding joint is active or the passive joint acceleration is computed from the residual link force if the corresponding joint is passive.

Adaptive Neural Network Control for the Trajectory Tracking of the Furuta Pendulum.

PubMed

Moreno-Valenzuela, Javier; Aguilar-Avelar, Carlos; Puga-Guzman, Sergio A; Santibanez, Victor

2016-12-01

The purpose of this paper is to introduce a novel adaptive neural network-based control scheme for the Furuta pendulum, which is a two degree-of-freedom underactuated system. Adaptation laws for the input and output weights are also provided. The proposed controller is able to guarantee tracking of a reference signal for the arm while the pendulum remains in the upright position. The key aspect of the derivation of the controller is the definition of an output function that depends on the position and velocity errors. The internal and external dynamics are rigorously analyzed, thereby proving the uniform ultimate boundedness of the error trajectories. By using real-time experiments, the new scheme is compared with other control methodologies, therein demonstrating the improved performance of the proposed adaptive algorithm.

Adaptive control of a quadrotor aerial vehicle with input constraints and uncertain parameters

NASA Astrophysics Data System (ADS)

Tran, Trong-Toan; Ge, Shuzhi Sam; He, Wei

2018-05-01

In this paper, we address the problem of adaptive bounded control for the trajectory tracking of a Quadrotor Aerial Vehicle (QAV) while the input saturations and uncertain parameters with the known bounds are simultaneously taken into account. First, to deal with the underactuated property of the QAV model, we decouple and construct the QAV model as a cascaded structure which consists of two fully actuated subsystems. Second, to handle the input constraints and uncertain parameters, we use a combination of the smooth saturation function and smooth projection operator in the control design. Third, to ensure the stability of the overall system of the QAV, we develop the technique for the cascaded system in the presence of both the input constraints and uncertain parameters. Finally, the region of stability of the closed-loop system is constructed explicitly, and our design ensures the asymptotic convergence of the tracking errors to the origin. The simulation results are provided to illustrate the effectiveness of the proposed method.

Learning in robotic manipulation: The role of dimensionality reduction in policy search methods. Comment on "Hand synergies: Integration of robotics and neuroscience for understanding the control of biological and artificial hands" by Marco Santello et al.

NASA Astrophysics Data System (ADS)

Ficuciello, Fanny; Siciliano, Bruno

2016-07-01

A question that often arises, among researchers working on artificial hands and robotic manipulation, concerns the real meaning of synergies. Namely, are they a realistic representation of the central nervous system control of manipulation activities at different levels and of the sensory-motor manipulation apparatus of the human being, or do they constitute just a theoretical framework exploiting analytical methods to simplify the representation of grasping and manipulation activities? Apparently, this is not a simple question to answer and, in this regard, many minds from the field of neuroscience and robotics are addressing the issue [1]. The interest of robotics is definitely oriented towards the adoption of synergies to tackle the control problem of devices with high number of degrees of freedom (DoFs) which are required to achieve motor and learning skills comparable to those of humans. The synergy concept is useful for innovative underactuated design of anthropomorphic hands [2], while the resulting dimensionality reduction simplifies the control of biomedical devices such as myoelectric hand prostheses [3]. Synergies might also be useful in conjunction with the learning process [4]. This aspect is less explored since few works on synergy-based learning have been realized in robotics. In learning new tasks through trial-and-error, physical interaction is important. On the other hand, advanced mechanical designs such as tendon-driven actuation, underactuated compliant mechanisms and hyper-redundant/continuum robots might exhibit enhanced capabilities of adapting to changing environments and learning from exploration. In particular, high DoFs and compliance increase the complexity of modelling and control of these devices. An analytical approach to manipulation planning requires a precise model of the object, an accurate description of the task, and an evaluation of the object affordance, which all make the process rather time consuming. The integration of learning into control naturally leads to relaxing the above requirements through the adoption of coordinated motion patterns and sensory-motor synergies as useful tools leading to a problem of reduced dimension. To this purpose, model-based control strategies relying on synergistic models of manipulation activities learned from human experience can be integrated with real-time learning from actions strategies [5]. In [6] a classification of learning strategies for robotics is provided, while the difference between imitation learning and reinforcement learning (RL) is highlighted in [7]. From recent research in the field [8,9], it seems that RL represents the future toward autonomous and intelligent robots since it provides learning capabilities as those of humans, i.e. based on exploration and trial-and-error policies. In this context, suitable policy search methods to be implemented in a synergy-based framework are to be sought in order to reduce the search space dimension while guaranteeing the convergence and efficiency of the learning algorithm.

Exploiting short-term memory in soft body dynamics as a computational resource.

PubMed

Nakajima, K; Li, T; Hauser, H; Pfeifer, R

2014-11-06

Soft materials are not only highly deformable, but they also possess rich and diverse body dynamics. Soft body dynamics exhibit a variety of properties, including nonlinearity, elasticity and potentially infinitely many degrees of freedom. Here, we demonstrate that such soft body dynamics can be employed to conduct certain types of computation. Using body dynamics generated from a soft silicone arm, we show that they can be exploited to emulate functions that require memory and to embed robust closed-loop control into the arm. Our results suggest that soft body dynamics have a short-term memory and can serve as a computational resource. This finding paves the way towards exploiting passive body dynamics for control of a large class of underactuated systems. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Linear active disturbance rejection control of underactuated systems: the case of the Furuta pendulum.

PubMed

Ramírez-Neria, M; Sira-Ramírez, H; Garrido-Moctezuma, R; Luviano-Juárez, A

2014-07-01

An Active Disturbance Rejection Control (ADRC) scheme is proposed for a trajectory tracking problem defined on a nonfeedback linearizable Furuta Pendulum example. A desired rest to rest angular position reference trajectory is to be tracked by the horizontal arm while the unactuated vertical pendulum arm stays around its unstable vertical position without falling down during the entire maneuver and long after it concludes. A linear observer-based linear controller of the ADRC type is designed on the basis of the flat tangent linearization of the system around an arbitrary equilibrium. The advantageous combination of flatness and the ADRC method makes it possible to on-line estimate and cancels the undesirable effects of the higher order nonlinearities disregarded by the linearization. These effects are triggered by fast horizontal arm tracking maneuvers driving the pendulum substantially away from the initial equilibrium point. Convincing experimental results, including a comparative test with a sliding mode controller, are presented. © 2013 ISA. Published by ISA. All rights reserved.

Mobile Manipulation and Mobility as Manipulation: Design and Algorithms of RoboSimian

DTIC Science & Technology

2014-05-01

feature was left out for the competition hands. The hand has three under-actuated fingers, each with a braided Dyneema R© tendon wrapped around pulleys at...models of objects (e.g. valves, ladders, hoses , etc.) into the world manually so that RoboSimian could interact with objects for manipulation. The remote...with a single button press (e.g. “rotate-valve”, “insert- hose ”, “push-open-door”), depending on the task. Note that since the plan module was run on

Error tracking control for underactuated overhead cranes against arbitrary initial payload swing angles

NASA Astrophysics Data System (ADS)

Zhang, Menghua; Ma, Xin; Rong, Xuewen; Tian, Xincheng; Li, Yibin

2017-02-01

This paper exploits an error tracking control method for overhead crane systems for which the error trajectories for the trolley and the payload swing can be pre-specified. The proposed method does not require that the initial payload swing angle remains zero, whereas this requirement is usually assumed in conventional methods. The significant feature of the proposed method is its superior control performance as well as its strong robustness over different or uncertain rope lengths, payload masses, desired positions, initial payload swing angles, and external disturbances. Owing to the same attenuation behavior, the desired error trajectory for the trolley for each traveling distance is not needed to be reset, which is easy to implement in practical applications. By converting the error tracking overhead crane dynamics to the objective system, we obtain the error tracking control law for arbitrary initial payload swing angles. Lyapunov techniques and LaSalle's invariance theorem are utilized to prove the convergence and stability of the closed-loop system. Simulation and experimental results are illustrated to validate the superior performance of the proposed error tracking control method.

A new look at the robust control of discrete-time Markov jump linear systems

NASA Astrophysics Data System (ADS)

Todorov, M. G.; Fragoso, M. D.

2016-03-01

In this paper, we make a foray in the role played by a set of four operators on the study of robust H2 and mixed H2/H∞ control problems for discrete-time Markov jump linear systems. These operators appear in the study of mean square stability for this class of systems. By means of new linear matrix inequality (LMI) characterisations of controllers, which include slack variables that, to some extent, separate the robustness and performance objectives, we introduce four alternative approaches to the design of controllers which are robustly stabilising and at the same time provide a guaranteed level of H2 performance. Since each operator provides a different degree of conservatism, the results are unified in the form of an iterative LMI technique for designing robust H2 controllers, whose convergence is attained in a finite number of steps. The method yields a new way of computing mixed H2/H∞ controllers, whose conservatism decreases with iteration. Two numerical examples illustrate the applicability of the proposed results for the control of a small unmanned aerial vehicle, and for an underactuated robotic arm.

Trajectory tracking in quadrotor platform by using PD controller and LQR control approach

NASA Astrophysics Data System (ADS)

Islam, Maidul; Okasha, Mohamed; Idres, Moumen Mohammad

2017-11-01

The purpose of the paper is to discuss a comparative evaluation of performance of two different controllers i.e. Proportional-Derivative Controller (PD) and Linear Quadratic Regulation (LQR) in Quadrotor dynamic system that is under-actuated with high nonlinearity. As only four states can be controlled at the same time in the Quadrotor, the trajectories are designed on the basis of the four states whereas three dimensional position and rotation along an axis, known as yaw movement are considered. In this work, both the PD controller and LQR control approach are used for Quadrotor nonlinear model to track the trajectories. LQR control approach for nonlinear model is designed on the basis of a linear model of the Quadrotor because the performance of linear model and nonlinear model around certain nominal point is almost similar. Simulink and MATLAB software is used to design the controllers and to evaluate the performance of both the controllers.

Decentralized Feedback Controllers for Exponential Stabilization of Hybrid Periodic Orbits: Application to Robotic Walking.

PubMed

Hamed, Kaveh Akbari; Gregg, Robert D

2016-07-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially stabilize periodic orbits for a class of hybrid dynamical systems arising from bipedal walking. The algorithm assumes a class of parameterized and nonlinear decentralized feedback controllers which coordinate lower-dimensional hybrid subsystems based on a common phasing variable. The exponential stabilization problem is translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities, which can be easily solved with available software packages. A set of sufficient conditions for the convergence of the iterative algorithm to a stabilizing decentralized feedback control solution is presented. The power of the algorithm is demonstrated by designing a set of local nonlinear controllers that cooperatively produce stable walking for a 3D autonomous biped with 9 degrees of freedom, 3 degrees of underactuation, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg.

Decentralized Feedback Controllers for Exponential Stabilization of Hybrid Periodic Orbits: Application to Robotic Walking*

PubMed Central

Hamed, Kaveh Akbari; Gregg, Robert D.

2016-01-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially stabilize periodic orbits for a class of hybrid dynamical systems arising from bipedal walking. The algorithm assumes a class of parameterized and nonlinear decentralized feedback controllers which coordinate lower-dimensional hybrid subsystems based on a common phasing variable. The exponential stabilization problem is translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities, which can be easily solved with available software packages. A set of sufficient conditions for the convergence of the iterative algorithm to a stabilizing decentralized feedback control solution is presented. The power of the algorithm is demonstrated by designing a set of local nonlinear controllers that cooperatively produce stable walking for a 3D autonomous biped with 9 degrees of freedom, 3 degrees of underactuation, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg. PMID:27990059

Experimental verification of a GPC-LPV method with RLS and P1-TS fuzzy-based estimation for limiting the transient and residual vibration of a crane system

NASA Astrophysics Data System (ADS)

Smoczek, Jaroslaw

2015-10-01

The paper deals with the problem of reducing the residual vibration and limiting the transient oscillations of a flexible and underactuated system with respect to the variation of operating conditions. The comparative study of generalized predictive control (GPC) and fuzzy scheduling scheme developed based on the P1-TS fuzzy theory, local pole placement method and interval analysis of closed-loop system polynomial coefficients is addressed to the problem of flexible crane control. The two alternatives of a GPC-based method are proposed that enable to realize this technique either with or without a sensor of payload deflection. The first control technique is based on the recursive least squares (RLS) method applied to on-line estimate the parameters of a linear parameter varying (LPV) model of a crane dynamic system. The second GPC-based approach is based on a payload deflection feedback estimated using a pendulum model with the parameters interpolated using the P1-TS fuzzy system. Feasibility and applicability of the developed methods were confirmed through experimental verification performed on a laboratory scaled overhead crane.

Robust Decentralized Nonlinear Control for a Twin Rotor MIMO System

PubMed Central

Belmonte, Lidia María; Morales, Rafael; Fernández-Caballero, Antonio; Somolinos, José Andrés

2016-01-01

This article presents the design of a novel decentralized nonlinear multivariate control scheme for an underactuated, nonlinear and multivariate laboratory helicopter denominated the twin rotor MIMO system (TRMS). The TRMS is characterized by a coupling effect between rotor dynamics and the body of the model, which is due to the action-reaction principle originated in the acceleration and deceleration of the motor-propeller groups. The proposed controller is composed of two nested loops that are utilized to achieve stabilization and precise trajectory tracking tasks for the controlled position of the generalized coordinates of the TRMS. The nonlinear internal loop is used to control the electrical dynamics of the platform, and the nonlinear external loop allows the platform to be perfectly stabilized and positioned in space. Finally, we illustrate the theoretical control developments with a set of experiments in order to verify the effectiveness of the proposed nonlinear decentralized feedback controller, in which a comparative study with other controllers is performed, illustrating the excellent performance of the proposed robust decentralized control scheme in both stabilization and trajectory tracking tasks. PMID:27472338

Robust Decentralized Nonlinear Control for a Twin Rotor MIMO System.

PubMed

Belmonte, Lidia María; Morales, Rafael; Fernández-Caballero, Antonio; Somolinos, José Andrés

2016-07-27

This article presents the design of a novel decentralized nonlinear multivariate control scheme for an underactuated, nonlinear and multivariate laboratory helicopter denominated the twin rotor MIMO system (TRMS). The TRMS is characterized by a coupling effect between rotor dynamics and the body of the model, which is due to the action-reaction principle originated in the acceleration and deceleration of the motor-propeller groups. The proposed controller is composed of two nested loops that are utilized to achieve stabilization and precise trajectory tracking tasks for the controlled position of the generalized coordinates of the TRMS. The nonlinear internal loop is used to control the electrical dynamics of the platform, and the nonlinear external loop allows the platform to be perfectly stabilized and positioned in space. Finally, we illustrate the theoretical control developments with a set of experiments in order to verify the effectiveness of the proposed nonlinear decentralized feedback controller, in which a comparative study with other controllers is performed, illustrating the excellent performance of the proposed robust decentralized control scheme in both stabilization and trajectory tracking tasks.

Quadcopter Path Following Control Design Using Output Feedback with Command Generator Tracker LOS Based At Square Path

NASA Astrophysics Data System (ADS)

Nugraha, A. T.; Agustinah, T.

2018-01-01

Quadcopter an unstable system, underactuated and nonlinear in quadcopter control research developments become an important focus of attention. In this study, following the path control method for position on the X and Y axis, used structure-Generator Tracker Command (CGT) is tested. Attitude control and position feedback quadcopter is compared using the optimal output. The addition of the H∞ performance optimal output feedback control is used to maintain the stability and robustness of quadcopter. Iterative numerical techniques Linear Matrix Inequality (LMI) is used to find the gain controller. The following path control problems is solved using the method of LQ regulators with output feedback. Simulations show that the control system can follow the paths that have been defined in the form of a reference signal square shape. The result of the simulation suggest that the method which used can bring the yaw angle at the expected value algorithm. Quadcopter can do automatically following path with cross track error mean X=0.5 m and Y=0.2 m.

Learning tactile skills through curious exploration

PubMed Central

Pape, Leo; Oddo, Calogero M.; Controzzi, Marco; Cipriani, Christian; Förster, Alexander; Carrozza, Maria C.; Schmidhuber, Jürgen

2012-01-01

We present curiosity-driven, autonomous acquisition of tactile exploratory skills on a biomimetic robot finger equipped with an array of microelectromechanical touch sensors. Instead of building tailored algorithms for solving a specific tactile task, we employ a more general curiosity-driven reinforcement learning approach that autonomously learns a set of motor skills in absence of an explicit teacher signal. In this approach, the acquisition of skills is driven by the information content of the sensory input signals relative to a learner that aims at representing sensory inputs using fewer and fewer computational resources. We show that, from initially random exploration of its environment, the robotic system autonomously develops a small set of basic motor skills that lead to different kinds of tactile input. Next, the system learns how to exploit the learned motor skills to solve supervised texture classification tasks. Our approach demonstrates the feasibility of autonomous acquisition of tactile skills on physical robotic platforms through curiosity-driven reinforcement learning, overcomes typical difficulties of engineered solutions for active tactile exploration and underactuated control, and provides a basis for studying developmental learning through intrinsic motivation in robots. PMID:22837748

Reducing Actuator Requirements in Continuum Robots Through Optimized Cable Routing.

PubMed

Case, Jennifer C; White, Edward L; SunSpiral, Vytas; Kramer-Bottiglio, Rebecca

2018-02-01

Continuum manipulators offer many advantages compared to their rigid-linked counterparts, such as increased degrees of freedom and workspace volume. Inspired by biological systems, such as elephant trunks and octopus tentacles, many continuum manipulators are made of multiple segments that allow large-scale deformations to be distributed throughout the body. Most continuum manipulators currently control each segment individually. For example, a planar cable-driven system is typically controlled by a pair of cables for each segment, which implies two actuators per segment. In this article, we demonstrate how highly coupled crossing cable configurations can reduce both actuator count and actuator torque requirements in a planar continuum manipulator, while maintaining workspace reachability and manipulability. We achieve highly coupled actuation by allowing cables to cross through the manipulator to create new cable configurations. We further derive an analytical model to predict the underactuated manipulator workspace and experimentally verify the model accuracy with a physical system. We use this model to compare crossing cable configurations to the traditional cable configuration using workspace performance metrics. Our work here focuses on a simplified planar robot, both in simulation and in hardware, with the goal of extending this to spiraling-cable configurations on full 3D continuum robots in future work.

Global fast dynamic terminal sliding mode control for a quadrotor UAV.

PubMed

Xiong, Jing-Jing; Zhang, Guo-Bao

2017-01-01

A control method based on global fast dynamic terminal sliding mode control (TSMC) technique is proposed to design the flight controller for performing the finite-time position and attitude tracking control of a small quadrotor UAV. Firstly, the dynamic model of the quadrotor is divided into two subsystems, i.e., a fully actuated subsystem and an underactuated subsystem. Secondly, the dynamic flight controllers of the quadrotor are formulated based on global fast dynamic TSMC, which is able to guarantee that the position and velocity tracking errors of all system state variables converge to zero in finite-time. Moreover, the global fast dynamic TSMC is also able to eliminate the chattering phenomenon caused by the switching control action and realize the high precision performance. In addition, the stabilities of two subsystems are demonstrated by Lyapunov theory, respectively. Lastly, the simulation results are given to illustrate the effectiveness and robustness of the proposed control method in the presence of external disturbances. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Subsea Cable Tracking by Autonomous Underwater Vehicle with Magnetic Sensing Guidance.

PubMed

Xiang, Xianbo; Yu, Caoyang; Niu, Zemin; Zhang, Qin

2016-08-20

The changes of the seabed environment caused by a natural disaster or human activities dramatically affect the life span of the subsea buried cable. It is essential to track the cable route in order to inspect the condition of the buried cable and protect its surviving seabed environment. The magnetic sensor is instrumental in guiding the remotely-operated vehicle (ROV) to track and inspect the buried cable underseas. In this paper, a novel framework integrating the underwater cable localization method with the magnetic guidance and control algorithm is proposed, in order to enable the automatic cable tracking by a three-degrees-of-freedom (3-DOF) under-actuated autonomous underwater vehicle (AUV) without human beings in the loop. The work relies on the passive magnetic sensing method to localize the subsea cable by using two tri-axial magnetometers, and a new analytic formulation is presented to compute the heading deviation, horizontal offset and buried depth of the cable. With the magnetic localization, the cable tracking and inspection mission is elaborately constructed as a straight-line path following control problem in the horizontal plane. A dedicated magnetic line-of-sight (LOS) guidance is built based on the relative geometric relationship between the vehicle and the cable, and the feedback linearizing technique is adopted to design a simplified cable tracking controller considering the side-slip effects, such that the under-actuated vehicle is able to move towards the subsea cable and then inspect its buried environment, which further guides the environmental protection of the cable by setting prohibited fishing/anchoring zones and increasing the buried depth. Finally, numerical simulation results show the effectiveness of the proposed magnetic guidance and control algorithm on the envisioned subsea cable tracking and the potential protection of the seabed environment along the cable route.

Subsea Cable Tracking by Autonomous Underwater Vehicle with Magnetic Sensing Guidance

PubMed Central

Xiang, Xianbo; Yu, Caoyang; Niu, Zemin; Zhang, Qin

2016-01-01

The changes of the seabed environment caused by a natural disaster or human activities dramatically affect the life span of the subsea buried cable. It is essential to track the cable route in order to inspect the condition of the buried cable and protect its surviving seabed environment. The magnetic sensor is instrumental in guiding the remotely-operated vehicle (ROV) to track and inspect the buried cable underseas. In this paper, a novel framework integrating the underwater cable localization method with the magnetic guidance and control algorithm is proposed, in order to enable the automatic cable tracking by a three-degrees-of-freedom (3-DOF) under-actuated autonomous underwater vehicle (AUV) without human beings in the loop. The work relies on the passive magnetic sensing method to localize the subsea cable by using two tri-axial magnetometers, and a new analytic formulation is presented to compute the heading deviation, horizontal offset and buried depth of the cable. With the magnetic localization, the cable tracking and inspection mission is elaborately constructed as a straight-line path following control problem in the horizontal plane. A dedicated magnetic line-of-sight (LOS) guidance is built based on the relative geometric relationship between the vehicle and the cable, and the feedback linearizing technique is adopted to design a simplified cable tracking controller considering the side-slip effects, such that the under-actuated vehicle is able to move towards the subsea cable and then inspect its buried environment, which further guides the environmental protection of the cable by setting prohibited fishing/anchoring zones and increasing the buried depth. Finally, numerical simulation results show the effectiveness of the proposed magnetic guidance and control algorithm on the envisioned subsea cable tracking and the potential protection of the seabed environment along the cable route. PMID:27556465

The SmartHand transradial prosthesis

PubMed Central

2011-01-01

Background Prosthetic components and control interfaces for upper limb amputees have barely changed in the past 40 years. Many transradial prostheses have been developed in the past, nonetheless most of them would be inappropriate if/when a large bandwidth human-machine interface for control and perception would be available, due to either their limited (or inexistent) sensorization or limited dexterity. SmartHand tackles this issue as is meant to be clinically experimented in amputees employing different neuro-interfaces, in order to investigate their effectiveness. This paper presents the design and on bench evaluation of the SmartHand. Methods SmartHand design was bio-inspired in terms of its physical appearance, kinematics, sensorization, and its multilevel control system. Underactuated fingers and differential mechanisms were designed and exploited in order to fit all mechatronic components in the size and weight of a natural human hand. Its sensory system was designed with the aim of delivering significant afferent information to the user through adequate interfaces. Results SmartHand is a five fingered self-contained robotic hand, with 16 degrees of freedom, actuated by 4 motors. It integrates a bio-inspired sensory system composed of 40 proprioceptive and exteroceptive sensors and a customized embedded controller both employed for implementing automatic grasp control and for potentially delivering sensory feedback to the amputee. It is able to perform everyday grasps, count and independently point the index. The weight (530 g) and speed (closing time: 1.5 seconds) are comparable to actual commercial prostheses. It is able to lift a 10 kg suitcase; slippage tests showed that within particular friction and geometric conditions the hand is able to stably grasp up to 3.6 kg cylindrical objects. Conclusions Due to its unique embedded features and human-size, the SmartHand holds the promise to be experimentally fitted on transradial amputees and employed as a bi-directional instrument for investigating -during realistic experiments- different interfaces, control and feedback strategies in neuro-engineering studies. PMID:21600048

Observer-based consensus of networked thrust-propelled vehicles with directed graphs.

PubMed

Cang, Weiye; Li, Zhongkui; Wang, Hanlei

2017-11-01

In this paper, we investigate the consensus problem for networked underactuated thrust-propelled vehicles (TPVs) interacting on directed graphs. We propose distributed observer-based consensus protocols, which avoid the reliance on the measurements of translational velocities and accelerations. Using the input-output analysis, we present necessary and sufficient conditions to ensure that the observer-based protocols can achieve consensus for both the cases without and with constant communication delays, provided that the communication graph contains a directed spanning tree. Simulation examples are finally provided to illustrate the effectiveness of the control schemes. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Dynamics and offset control of tethered space-tug system

NASA Astrophysics Data System (ADS)

Zhang, Jingrui; Yang, Keying; Qi, Rui

2018-01-01

Tethered space-tug system is regarded as one of the most promising active debris removal technologies to effectively decrease the steep increasing population of space debris. In order to suppress the spin of space debris, single-tethered space-tug system is employed by regulating the tether. Unfortunately, this system is underactuated as tether length is the only input, and there are two control objectives: the spinning debris and the vibration of tether. Thus, it may suffer great oscillations and result in failure in space debris removal. This paper presents the study of attitude stabilization of the single-tethered space-tug system using not only tether length but also the offset of tether attachment point to suppress the spin of debris, so as to accomplish the space debris removal mission. Firstly, a precise 3D mathematical model in which the debris and tug are both treated as rigid bodies is developed to study the dynamical evolution of the tethered space-tug system. The relative motion equation of the system is described using Lagrange method. Secondly, the dynamic characteristic of the system is analyzed and an offset control law is designed to stabilize the spin of debris by exploiting the variation of tether offset and the regulation of tether length. Besides, an estimation formula is proposed to evaluate the capability of tether for suppressing spinning debris. Finally, the effectiveness of attitude stabilization by the utilization of the proposed scheme is demonstrated via numerical case studies.

Single-Grasp Object Classification and Feature Extraction with Simple Robot Hands and Tactile Sensors.

PubMed

Spiers, Adam J; Liarokapis, Minas V; Calli, Berk; Dollar, Aaron M

2016-01-01

Classical robotic approaches to tactile object identification often involve rigid mechanical grippers, dense sensor arrays, and exploratory procedures (EPs). Though EPs are a natural method for humans to acquire object information, evidence also exists for meaningful tactile property inference from brief, non-exploratory motions (a 'haptic glance'). In this work, we implement tactile object identification and feature extraction techniques on data acquired during a single, unplanned grasp with a simple, underactuated robot hand equipped with inexpensive barometric pressure sensors. Our methodology utilizes two cooperating schemes based on an advanced machine learning technique (random forests) and parametric methods that estimate object properties. The available data is limited to actuator positions (one per two link finger) and force sensors values (eight per finger). The schemes are able to work both independently and collaboratively, depending on the task scenario. When collaborating, the results of each method contribute to the other, improving the overall result in a synergistic fashion. Unlike prior work, the proposed approach does not require object exploration, re-grasping, grasp-release, or force modulation and works for arbitrary object start positions and orientations. Due to these factors, the technique may be integrated into practical robotic grasping scenarios without adding time or manipulation overheads.

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. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Predictability, Force and (Anti-)Resonance in Complex Object Control.

PubMed

Maurice, Pauline; Hogan, Neville; Sternad, Dagmar

2018-04-18

Manipulation of complex objects as in tool use is ubiquitous and has given humans an evolutionary advantage. This study examined the strategies humans choose when manipulating an object with underactuated internal dynamics, such as a cup of coffee. The object's dynamics renders the temporal evolution complex, possibly even chaotic, and difficult to predict. A cart-and-pendulum model, loosely mimicking coffee sloshing in a cup, was implemented in a virtual environment with a haptic interface. Participants rhythmically manipulated the virtual cup containing a rolling ball; they could choose the oscillation frequency, while the amplitude was prescribed. Three hypotheses were tested: 1) humans decrease interaction forces between hand and object; 2) humans increase the predictability of the object dynamics; 3) humans exploit the resonances of the coupled object-hand system. Analysis revealed that humans chose either a high-frequency strategy with anti-phase cup-and-ball movements or a low-frequency strategy with in-phase cup-and-ball movements. Counter Hypothesis 1, they did not decrease interaction force; instead, they increased the predictability of the interaction dynamics, quantified by mutual information, supporting Hypothesis 2. To address Hypothesis 3, frequency analysis of the coupled hand-object system revealed two resonance frequencies separated by an anti-resonance frequency. The low-frequency strategy exploited one resonance, while the high-frequency strategy afforded more choice, consistent with the frequency response of the coupled system; both strategies avoided the anti-resonance. Hence, humans did not prioritize interaction force, but rather strategies that rendered interactions predictable. These findings highlight that physical interactions with complex objects pose control challenges not present in unconstrained movements.

Dynamics modelling and Hybrid Suppression Control of space robots performing cooperative object manipulation

NASA Astrophysics Data System (ADS)

Zarafshan, P.; Moosavian, S. Ali A.

2013-10-01

Dynamics modelling and control of multi-body space robotic systems composed of rigid and flexible elements is elaborated here. Control of such systems is highly complicated due to severe under-actuated condition caused by flexible elements, and an inherent uneven nonlinear dynamics. Therefore, developing a compact dynamics model with the requirement of limited computations is extremely useful for controller design, also to develop simulation studies in support of design improvement, and finally for practical implementations. In this paper, the Rigid-Flexible Interactive dynamics Modelling (RFIM) approach is introduced as a combination of Lagrange and Newton-Euler methods, in which the motion equations of rigid and flexible members are separately developed in an explicit closed form. These equations are then assembled and solved simultaneously at each time step by considering the mutual interaction and constraint forces. The proposed approach yields a compact model rather than common accumulation approach that leads to a massive set of equations in which the dynamics of flexible elements is united with the dynamics equations of rigid members. To reveal such merits of this new approach, a Hybrid Suppression Control (HSC) for a cooperative object manipulation task will be proposed, and applied to usual space systems. A Wheeled Mobile Robotic (WMR) system with flexible appendages as a typical space rover is considered which contains a rigid main body equipped with two manipulating arms and two flexible solar panels, and next a Space Free Flying Robotic system (SFFR) with flexible members is studied. Modelling verification of these complicated systems is vigorously performed using ANSYS and ADAMS programs, while the limited computations of RFIM approach provides an efficient tool for the proposed controller design. Furthermore, it will be shown that the vibrations of the flexible solar panels results in disturbing forces on the base which may produce undesirable errors and perturb the object manipulation task. So, it is shown that these effects can be significantly eliminated by the proposed Hybrid Suppression Control algorithm.

Predictability and Robustness in the Manipulation of Dynamically Complex Objects

PubMed Central

Hasson, Christopher J.

2017-01-01

Manipulation of complex objects and tools is a hallmark of many activities of daily living, but how the human neuromotor control system interacts with such objects is not well understood. Even the seemingly simple task of transporting a cup of coffee without spilling creates complex interaction forces that humans need to compensate for. Predicting the behavior of an underactuated object with nonlinear fluid dynamics based on an internal model appears daunting. Hence, this research tests the hypothesis that humans learn strategies that make interactions predictable and robust to inaccuracies in neural representations of object dynamics. The task of moving a cup of coffee is modeled with a cart-and-pendulum system that is rendered in a virtual environment, where subjects interact with a virtual cup with a rolling ball inside using a robotic manipulandum. To gain insight into human control strategies, we operationalize predictability and robustness to permit quantitative theory-based assessment. Predictability is quantified by the mutual information between the applied force and the object dynamics; robustness is quantified by the energy margin away from failure. Three studies are reviewed that show how with practice subjects develop movement strategies that are predictable and robust. Alternative criteria, common for free movement, such as maximization of smoothness and minimization of force, do not account for the observed data. As manual dexterity is compromised in many individuals with neurological disorders, the experimental paradigm and its analyses are a promising platform to gain insights into neurological diseases, such as dystonia and multiple sclerosis, as well as healthy aging. PMID:28035560

Integrated guidance and control for microsatellite real-time automated proximity operations

NASA Astrophysics Data System (ADS)

Chen, Ying; He, Zhen; Zhou, Ding; Yu, Zhenhua; Li, Shunli

2018-07-01

This paper investigates the trajectory planning and control of autonomous spacecraft proximity operations with impulsive dynamics. A new integrated guidance and control scheme is developed to perform automated close-range rendezvous for underactuated microsatellites. To efficiently prevent collision, a modified RRT* trajectory planning algorithm is proposed under this context. Several engineering constraints such as collision avoidance, plume impingement, field of view and control feasibility are considered simultaneously. Then, the feedback controller that employs a turn-burn-turn strategy with a combined impulsive orbital control and finite-time attitude control is designed to ensure the implementation of planned trajectory. Finally, the performance of trajectory planner and controller are evaluated through numerical tests. Simulation results indicate the real-time implementability of the proposed integrated guidance and control scheme with position control error less than 0.5 m and velocity control error less than 0.05 m/s. Consequently, the proposed scheme offers the potential for wide applications, such as on-orbit maintenance, space surveillance and debris removal.

Kernel-based least squares policy iteration for reinforcement learning.

PubMed

Xu, Xin; Hu, Dewen; Lu, Xicheng

2007-07-01

In this paper, we present a kernel-based least squares policy iteration (KLSPI) algorithm for reinforcement learning (RL) in large or continuous state spaces, which can be used to realize adaptive feedback control of uncertain dynamic systems. By using KLSPI, near-optimal control policies can be obtained without much a priori knowledge on dynamic models of control plants. In KLSPI, Mercer kernels are used in the policy evaluation of a policy iteration process, where a new kernel-based least squares temporal-difference algorithm called KLSTD-Q is proposed for efficient policy evaluation. To keep the sparsity and improve the generalization ability of KLSTD-Q solutions, a kernel sparsification procedure based on approximate linear dependency (ALD) is performed. Compared to the previous works on approximate RL methods, KLSPI makes two progresses to eliminate the main difficulties of existing results. One is the better convergence and (near) optimality guarantee by using the KLSTD-Q algorithm for policy evaluation with high precision. The other is the automatic feature selection using the ALD-based kernel sparsification. Therefore, the KLSPI algorithm provides a general RL method with generalization performance and convergence guarantee for large-scale Markov decision problems (MDPs). Experimental results on a typical RL task for a stochastic chain problem demonstrate that KLSPI can consistently achieve better learning efficiency and policy quality than the previous least squares policy iteration (LSPI) algorithm. Furthermore, the KLSPI method was also evaluated on two nonlinear feedback control problems, including a ship heading control problem and the swing up control of a double-link underactuated pendulum called acrobot. Simulation results illustrate that the proposed method can optimize controller performance using little a priori information of uncertain dynamic systems. It is also demonstrated that KLSPI can be applied to online learning control by incorporating an initial controller to ensure online performance.

Fast grasping of unknown objects using cylinder searching on a single point cloud

NASA Astrophysics Data System (ADS)

Lei, Qujiang; Wisse, Martijn

2017-03-01

Grasping of unknown objects with neither appearance data nor object models given in advance is very important for robots that work in an unfamiliar environment. The goal of this paper is to quickly synthesize an executable grasp for one unknown object by using cylinder searching on a single point cloud. Specifically, a 3D camera is first used to obtain a partial point cloud of the target unknown object. An original method is then employed to do post treatment on the partial point cloud to minimize the uncertainty which may lead to grasp failure. In order to accelerate the grasp searching, surface normal of the target object is then used to constrain the synthetization of the cylinder grasp candidates. Operability analysis is then used to select out all executable grasp candidates followed by force balance optimization to choose the most reliable grasp as the final grasp execution. In order to verify the effectiveness of our algorithm, Simulations on a Universal Robot arm UR5 and an under-actuated Lacquey Fetch gripper are used to examine the performance of this algorithm, and successful results are obtained.

Developing a 3-DOF Compliant Perching Arm for a Free-Flying Robot on the International Space Station

NASA Technical Reports Server (NTRS)

Park, In-Won; Smith, Marion F.; Sanchez, Hugo S.; Wong, Sze Wun; Piacenza, Pedro; Ciocarlie, Matei

2017-01-01

This paper presents the design and control of the 3-DOF compliant perching arm for the free-flying Astrobee robots that will operate inside the International Space Station (ISS). The robots are intended to serve as a flexible platform for future guest scientists to use for zero-gravity robotics research - thus, the arm is designed to support manipulation research. It provides a 1-DOF underactuated tendon-driven gripper capable of enveloping a range of objects of different shapes and sizes. Co-located RGB camera and LIDAR sensors provide perception. The Astrobee robots will be capable of grasping each other in flight, to simulate orbital capture scenarios. The arm's end-effector module is swappable on-orbit, allowing guest scientists to add upgraded grippers, or even additional arm degrees of freedom. The design of the arm balances research capabilities with Astrobee's operational need to perch on ISS handrails to reduce power consumption. Basic arm functioning and grip strength were evaluated using an integrated Astrobee prototype riding on a low-friction air bearing.

Control of human gait stability through foot placement.

PubMed

Bruijn, Sjoerd M; van Dieën, Jaap H

2018-06-01

During human walking, the centre of mass (CoM) is outside the base of support for most of the time, which poses a challenge to stabilizing the gait pattern. Nevertheless, most of us are able to walk without substantial problems. In this review, we aim to provide an integrative overview of how humans cope with an underactuated gait pattern. A central idea that emerges from the literature is that foot placement is crucial in maintaining a stable gait pattern. In this review, we explore this idea; we first describe mechanical models and concepts that have been used to predict how foot placement can be used to control gait stability. These concepts, such as for instance the extrapolated CoM concept, the foot placement estimator concept and the capture point concept, provide explicit predictions on where to place the foot relative to the body at each step, such that gait is stabilized. Next, we describe empirical findings on foot placement during human gait in unperturbed and perturbed conditions. We conclude that humans show behaviour that is largely in accordance with the aforementioned concepts, with foot placement being actively coordinated to body CoM kinematics during the preceding step. In this section, we also address the requirements for such control in terms of the sensory information and the motor strategies that can implement such control, as well as the parts of the central nervous system that may be involved. We show that visual, vestibular and proprioceptive information contribute to estimation of the state of the CoM. Foot placement is adjusted to variations in CoM state mainly by modulation of hip abductor muscle activity during the swing phase of gait, and this process appears to be under spinal and supraspinal, including cortical, control. We conclude with a description of how control of foot placement can be impaired in humans, using ageing as a primary example and with some reference to pathology, and we address alternative strategies available to stabilize gait, which include modulation of ankle moments in the stance leg and changes in body angular momentum, such as rapid trunk tilts. Finally, for future research, we believe that especially the integration of consideration of environmental constraints on foot placement with balance control deserves attention. © 2018 The Authors.

A role of abdomen in butterfly's flapping flight

NASA Astrophysics Data System (ADS)

Jayakumar, Jeeva; Senda, Kei; Yokoyama, Naoto

2017-11-01

Butterfly's forward flight with periodic flapping motion is longitudinally unstable, and control of the thoracic pitching angle is essential to stabilize the flight. This study aims to comprehend roles which the abdominal motion play in the pitching stability of butterfly's flapping flight by using a two-dimensional model. The control of the thoracic pitching angle by the abdominal motion is an underactuated problem because of the limit on the abdominal angle. The control input of the thorax-abdomen joint torque is obtained by the hierarchical sliding mode control in this study. Numerical simulations reveal that the control by the abdominal motion provides short-term pitching stabilization in the butterfly's flight. Moreover, the control input due to a large thorax-abdomen joint torque can counteract a quite large perturbation, and can return the pitching attitude to the periodic trajectory with a short recovery time. These observations are consistent with biologists' view that living butterflies use their abdomens as rudders. On the other hand, the abdominal control mostly fails in long-term pitching stabilization, because it cannot directly alter the aerodynamic forces. The control for the long-term pitching stabilization will also be discussed.

Design and Evolution of a Modular Tensegrity Robot Platform

NASA Technical Reports Server (NTRS)

Bruce, Jonathan; Caluwaerts, Ken; Iscen, Atil; Sabelhaus, Andrew P.; SunSpiral, Vytas

2014-01-01

NASA Ames Research Center is developing a compliant modular tensegrity robotic platform for planetary exploration. In this paper we present the design and evolution of the platform's main hardware component, an untethered, robust tensegrity strut, with rich sensor feedback and cable actuation. Each strut is a complete robot, and multiple struts can be combined together to form a wide range of complex tensegrity robots. Our current goal for the tensegrity robotic platform is the development of SUPERball, a 6-strut icosahedron underactuated tensegrity robot aimed at dynamic locomotion for planetary exploration rovers and landers, but the aim is for the modular strut to enable a wide range of tensegrity morphologies. SUPERball is a second generation prototype, evolving from the tensegrity robot ReCTeR, which is also a modular, lightweight, highly compliant 6-strut tensegrity robot that was used to validate our physics based NASA Tensegrity Robot Toolkit (NTRT) simulator. Many hardware design parameters of the SUPERball were driven by locomotion results obtained in our validated simulator. These evolutionary explorations helped constrain motor torque and speed parameters, along with strut and string stress. As construction of the hardware has finalized, we have also used the same evolutionary framework to evolve controllers that respect the built hardware parameters.

Output feedback control of a quadrotor UAV using neural networks.

PubMed

Dierks, Travis; Jagannathan, Sarangapani

2010-01-01

In this paper, a new nonlinear controller for a quadrotor unmanned aerial vehicle (UAV) is proposed using neural networks (NNs) and output feedback. The assumption on the availability of UAV dynamics is not always practical, especially in an outdoor environment. Therefore, in this work, an NN is introduced to learn the complete dynamics of the UAV online, including uncertain nonlinear terms like aerodynamic friction and blade flapping. Although a quadrotor UAV is underactuated, a novel NN virtual control input scheme is proposed which allows all six degrees of freedom (DOF) of the UAV to be controlled using only four control inputs. Furthermore, an NN observer is introduced to estimate the translational and angular velocities of the UAV, and an output feedback control law is developed in which only the position and the attitude of the UAV are considered measurable. It is shown using Lyapunov theory that the position, orientation, and velocity tracking errors, the virtual control and observer estimation errors, and the NN weight estimation errors for each NN are all semiglobally uniformly ultimately bounded (SGUUB) in the presence of bounded disturbances and NN functional reconstruction errors while simultaneously relaxing the separation principle. The effectiveness of proposed output feedback control scheme is then demonstrated in the presence of unknown nonlinear dynamics and disturbances, and simulation results are included to demonstrate the theoretical conjecture.

Position, Attitude, and Fault-Tolerant Control of Tilting-Rotor Quadcopter

NASA Astrophysics Data System (ADS)

Kumar, Rumit

The aim of this thesis is to present algorithms for autonomous control of tilt-rotor quadcopter UAV. In particular, this research work describes position, attitude and fault tolerant control in tilt-rotor quadcopter. Quadcopters are one of the most popular and reliable unmanned aerial systems because of the design simplicity, hovering capabilities and minimal operational cost. Numerous applications for quadcopters have been explored all over the world but very little work has been done to explore design enhancements and address the fault-tolerant capabilities of the quadcopters. The tilting rotor quadcopter is a structural advancement of traditional quadcopter and it provides additional actuated controls as the propeller motors are actuated for tilt which can be utilized to improve efficiency of the aerial vehicle during flight. The tilting rotor quadcopter design is accomplished by using an additional servo motor for each rotor that enables the rotor to tilt about the axis of the quadcopter arm. Tilting rotor quadcopter is a more agile version of conventional quadcopter and it is a fully actuated system. The tilt-rotor quadcopter is capable of following complex trajectories with ease. The control strategy in this work is to use the propeller tilts for position and orientation control during autonomous flight of the quadcopter. In conventional quadcopters, two propellers rotate in clockwise direction and other two propellers rotate in counter clockwise direction to cancel out the effective yawing moment of the system. The variation in rotational speeds of these four propellers is utilized for maneuvering. On the other hand, this work incorporates use of varying propeller rotational speeds along with tilting of the propellers for maneuvering during flight. The rotational motion of propellers work in sync with propeller tilts to control the position and orientation of the UAV during the flight. A PD flight controller is developed to achieve various modes of the flight. Further, the performance of the controller and the tilt-rotor design has been compared with respect to the conventional quadcopter in the presence of wind disturbances and sensor uncertainties. In this work, another novel feed-forward control design approach is presented for complex trajectory tracking during autonomous flight. Differential flatness based feed-forward position control is employed to enhance the performance of the UAV during complex trajectory tracking. By accounting for differential flatness based feed-forward control input parameters, a new PD controller is designed to achieve the desired performance in autonomous flight. The results for tracking complex trajectories have been presented by performing numerical simulations with and without environmental uncertainties to demonstrate robustness of the controller during flight. The conventional quadcopters are under-actuated systems and, upon failure of one propeller, the conventional quadcopter would have a tendency of spinning about the primary axis fixed to the vehicle as an outcome of the asymmetry in resultant yawing moment in the system. In this work, control of tilt-rotor quadcopter is presented upon failure of one propeller during flight. The tilt-rotor quadcopter is capable of handling a propeller failure and hence is a fault-tolerant system. The dynamic model of tilting-rotor quadcopter with one propeller failure is derived and a controller has been designed to achieve hovering and navigation capability. The simulation results of way point navigation, complex trajectory tracking and fault-tolerance are presented.

46 CFR 154.1200 - Mechanical ventilation system: General.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Mechanical ventilation system: General. 154.1200 Section... Equipment Cargo Area: Mechanical Ventilation System § 154.1200 Mechanical ventilation system: General. (a... cargo handling equipment must have a fixed, exhaust-type mechanical ventilation system. (b) The...

Passive stability and actuation of micro aerial vehicles

NASA Astrophysics Data System (ADS)

Piccoli, Matthew

Micro Aerial Vehicles (MAVs) have increased in popularity in recent years. The most common platform, the quadrotor, has surpassed other MAVs like traditional helicopters and ornithopters in popularity mainly due to their simplicity. Yet the quadrotor design is a century old and was intended to carry people. We set out to design a MAV that is designed specifically to be a MAV, i.e. a vehicle not intended to carry humans as a payload. With this constraint lifted the vehicle can continuously rotate, which would dizzy a human, can sustain larger forces, which would damage a human, or can take advantage of scaling properties, where it may not work at human scale. Furthermore, we aim for simplicity by removing vehicle controllers and reducing the number of actuators, such that the vehicle can be made cost effective, if not disposable. We begin by studying general equations of motion for hovering MAVs. We search for vehicle configurations that exhibit passive stability, allowing the MAV to operate without a controller or actuators to apply control, ideally a single actuator. The analysis suggests two distinct types of passively stabilized MAVs and we create test vehicles for both. With simple hovering achieved, we concentrate on controlled motion with an emphasis on doing so without adding actuators. We find we can attain three degree of freedom control using separation of time scales with our actuator via low frequency for control in the vertical direction and high frequency for control in the horizontal plane. We explore techniques for achieving high frequency actuator control, which also allow the compensation of motor defects, specifically cogging torque. We combine passive stability with the motion control into two vehicles, UNO and Piccolissimo. UNO, the Underactuated-propeller Naturally-stabilized One-motor vehicle, demonstrates the capabilities of simple vehicles by performing maneuvers like conventional quadrotors. Piccolissimo, Italian for very little, demonstrates the merits of passive stability and single actuator control by being the smallest, self-powered, controllable MAV.

Assessment of Myoelectric Controller Performance and Kinematic Behavior of a Novel Soft Synergy-Inspired Robotic Hand for Prosthetic Applications

PubMed Central

Fani, Simone; Bianchi, Matteo; Jain, Sonal; Pimenta Neto, José Simões; Boege, Scott; Grioli, Giorgio; Bicchi, Antonio; Santello, Marco

2016-01-01

Myoelectric artificial limbs can significantly advance the state of the art in prosthetics, since they can be used to control mechatronic devices through muscular activity in a way that mimics how the subjects used to activate their muscles before limb loss. However, surveys indicate that dissatisfaction with the functionality of terminal devices underlies the widespread abandonment of prostheses. We believe that one key factor to improve acceptability of prosthetic devices is to attain human likeness of prosthesis movements, a goal which is being pursued by research on social and human–robot interactions. Therefore, to reduce early abandonment of terminal devices, we propose that controllers should be designed so as to ensure effective task accomplishment in a natural fashion. In this work, we have analyzed and compared the performance of three types of myoelectric controller algorithms based on surface electromyography to control an underactuated and multi-degrees of freedom prosthetic hand, the SoftHand Pro. The goal of the present study was to identify the myoelectric algorithm that best mimics the native hand movements. As a preliminary step, we first quantified the repeatability of the SoftHand Pro finger movements and identified the electromyographic recording sites for able-bodied individuals with the highest signal-to-noise ratio from two pairs of muscles, i.e., flexor digitorum superficialis/extensor digitorum communis, and flexor carpi radialis/extensor carpi ulnaris. Able-bodied volunteers were then asked to execute reach-to-grasp movements, while electromyography signals were recorded from flexor digitorum superficialis/extensor digitorum communis as this was identified as the muscle pair characterized by high signal-to-noise ratio and intuitive control. Subsequently, we tested three myoelectric controllers that mapped electromyography signals to position of the SoftHand Pro. We found that a differential electromyography-to-position mapping ensured the highest coherence with hand movements. Our results represent a first step toward a more effective and intuitive control of myoelectric hand prostheses. PMID:27799908

46 CFR 154.1205 - Mechanical ventilation system: Standards.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Mechanical ventilation system: Standards. 154.1205... Equipment Cargo Area: Mechanical Ventilation System § 154.1205 Mechanical ventilation system: Standards. (a) Each exhaust type mechanical ventilation system required under § 154.1200 (a) must have ducts for...

Mechanical systems: A compilation

NASA Technical Reports Server (NTRS)

1975-01-01

A compilation of several mechanized systems is presented. The articles are contained in three sections: robotics, industrial mechanical systems, including several on linear and rotary systems and lastly mechanical control systems, such as brakes and clutches.

Numerical simulation of volume-controlled mechanical ventilated respiratory system with 2 different lungs.

PubMed

Shi, Yan; Zhang, Bolun; Cai, Maolin; Zhang, Xiaohua Douglas

2017-09-01

Mechanical ventilation is a key therapy for patients who cannot breathe adequately by themselves, and dynamics of mechanical ventilation system is of great significance for life support of patients. Recently, models of mechanical ventilated respiratory system with 1 lung are used to simulate the respiratory system of patients. However, humans have 2 lungs. When the respiratory characteristics of 2 lungs are different, a single-lung model cannot reflect real respiratory system. In this paper, to illustrate dynamic characteristics of mechanical ventilated respiratory system with 2 different lungs, we propose a mathematical model of mechanical ventilated respiratory system with 2 different lungs and conduct experiments to verify the model. Furthermore, we study the dynamics of mechanical ventilated respiratory system with 2 different lungs. This research study can be used for improving the efficiency and safety of volume-controlled mechanical ventilation system. Copyright © 2016 John Wiley & Sons, Ltd.

46 CFR 113.35-9 - Mechanical engine order telegraph systems.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Mechanical engine order telegraph systems. 113.35-9... COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-9 Mechanical engine order telegraph systems. (a) Each mechanical engine order telegraph system must consist of transmitters and...

46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Mechanical engine order telegraph systems; application...-15 Mechanical engine order telegraph systems; application. If a mechanical engine order telegraph... cables or other mechanical limitations must not prevent the efficient operation of the system. ...

The Architect's Guide to Mechanical Systems.

ERIC Educational Resources Information Center

Andrews, F. T.

The principles and problems of designing new building mechanical systems are discussed in this reference source in the light of data on the functions and operation of mechanical systems. As a practical guide to understanding mechanical systems it describes system types, functions, space requirements, weights, installation, maintenance and…

46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Mechanical engine order telegraph systems; application...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-15 Mechanical engine order telegraph systems; application. If a mechanical engine order telegraph...

46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Mechanical engine order telegraph systems; application...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-15 Mechanical engine order telegraph systems; application. If a mechanical engine order telegraph...

46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Mechanical engine order telegraph systems; application...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-15 Mechanical engine order telegraph systems; application. If a mechanical engine order telegraph...

46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Mechanical engine order telegraph systems; application...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-15 Mechanical engine order telegraph systems; application. If a mechanical engine order telegraph...

Mechanical system reliability for long life space systems

NASA Technical Reports Server (NTRS)

Kowal, Michael T.

1994-01-01

The creation of a compendium of mechanical limit states was undertaken in order to provide a reference base for the application of first-order reliability methods to mechanical systems in the context of the development of a system level design methodology. The compendium was conceived as a reference source specific to the problem of developing the noted design methodology, and not an exhaustive or exclusive compilation of mechanical limit states. The compendium is not intended to be a handbook of mechanical limit states for general use. The compendium provides a diverse set of limit-state relationships for use in demonstrating the application of probabilistic reliability methods to mechanical systems. The compendium is to be used in the reliability analysis of moderately complex mechanical systems.

46 CFR 154.506 - Mechanical expansion joint: Limits in a piping system.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 5 2013-10-01 2013-10-01 false Mechanical expansion joint: Limits in a piping system..., Construction and Equipment Cargo and Process Piping Systems § 154.506 Mechanical expansion joint: Limits in a piping system. Mechanical expansion joints in a piping system outside of a cargo tank: (a) May be...

46 CFR 154.506 - Mechanical expansion joint: Limits in a piping system.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 5 2014-10-01 2014-10-01 false Mechanical expansion joint: Limits in a piping system..., Construction and Equipment Cargo and Process Piping Systems § 154.506 Mechanical expansion joint: Limits in a piping system. Mechanical expansion joints in a piping system outside of a cargo tank: (a) May be...

46 CFR 154.506 - Mechanical expansion joint: Limits in a piping system.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false Mechanical expansion joint: Limits in a piping system..., Construction and Equipment Cargo and Process Piping Systems § 154.506 Mechanical expansion joint: Limits in a piping system. Mechanical expansion joints in a piping system outside of a cargo tank: (a) May be...

46 CFR 154.506 - Mechanical expansion joint: Limits in a piping system.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 5 2012-10-01 2012-10-01 false Mechanical expansion joint: Limits in a piping system..., Construction and Equipment Cargo and Process Piping Systems § 154.506 Mechanical expansion joint: Limits in a piping system. Mechanical expansion joints in a piping system outside of a cargo tank: (a) May be...

46 CFR 154.506 - Mechanical expansion joint: Limits in a piping system.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Mechanical expansion joint: Limits in a piping system..., Construction and Equipment Cargo and Process Piping Systems § 154.506 Mechanical expansion joint: Limits in a piping system. Mechanical expansion joints in a piping system outside of a cargo tank: (a) May be...

Mechanical Systems

NASA Technical Reports Server (NTRS)

Davis, Robert E.

2002-01-01

The presentation provides an overview of requirement and interpretation letters, mechanical systems safety interpretation letter, design and verification provisions, and mechanical systems verification plan.

Flash memory management system and method utilizing multiple block list windows

NASA Technical Reports Server (NTRS)

Chow, James (Inventor); Gender, Thomas K. (Inventor)

2005-01-01

The present invention provides a flash memory management system and method with increased performance. The flash memory management system provides the ability to efficiently manage and allocate flash memory use in a way that improves reliability and longevity, while maintaining good performance levels. The flash memory management system includes a free block mechanism, a disk maintenance mechanism, and a bad block detection mechanism. The free block mechanism provides efficient sorting of free blocks to facilitate selecting low use blocks for writing. The disk maintenance mechanism provides for the ability to efficiently clean flash memory blocks during processor idle times. The bad block detection mechanism provides the ability to better detect when a block of flash memory is likely to go bad. The flash status mechanism stores information in fast access memory that describes the content and status of the data in the flash disk. The new bank detection mechanism provides the ability to automatically detect when new banks of flash memory are added to the system. Together, these mechanisms provide a flash memory management system that can improve the operational efficiency of systems that utilize flash memory.

14 CFR 27.923 - Rotor drive system and control mechanism tests.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Rotor drive system and control mechanism....923 Rotor drive system and control mechanism tests. (a) Each part tested as prescribed in this section... affect test results may be conducted. (b) Each rotor drive system and control mechanism must be tested...

14 CFR 27.923 - Rotor drive system and control mechanism tests.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Rotor drive system and control mechanism....923 Rotor drive system and control mechanism tests. (a) Each part tested as prescribed in this section... affect test results may be conducted. (b) Each rotor drive system and control mechanism must be tested...

Pressure Dynamic Characteristics of Pressure Controlled Ventilation System of a Lung Simulator

PubMed Central

Shi, Yan; Ren, Shuai; Cai, Maolin; Xu, Weiqing; Deng, Qiyou

2014-01-01

Mechanical ventilation is an important life support treatment of critically ill patients, and air pressure dynamics of human lung affect ventilation treatment effects. In this paper, in order to obtain the influences of seven key parameters of mechanical ventilation system on the pressure dynamics of human lung, firstly, mechanical ventilation system was considered as a pure pneumatic system, and then its mathematical model was set up. Furthermore, to verify the mathematical model, a prototype mechanical ventilation system of a lung simulator was proposed for experimental study. Last, simulation and experimental studies on the air flow dynamic of the mechanical ventilation system were done, and then the pressure dynamic characteristics of the mechanical system were obtained. The study can be referred to in the pulmonary diagnostics, treatment, and design of various medical devices or diagnostic systems. PMID:25197318

An opto-electro-mechanical system based on evanescently-coupled optical microbottle and electromechanical resonator

NASA Astrophysics Data System (ADS)

Asano, Motoki; Ohta, Ryuichi; Yamamoto, Takashi; Okamoto, Hajime; Yamaguchi, Hiroshi

2018-05-01

Evanescent coupling between a high-Q silica optical microbottle and a GaAs electromechanical resonator is demonstrated. This coupling offers an opto-electro-mechanical system which possesses both cavity-enhanced optical sensitivity and electrical controllability of the mechanical motion. Cooling and heating of the mechanical mode are demonstrated based on optomechanical detection via the radiation pressure and electromechanical feedback via the piezoelectric effect. This evanescent approach allows for individual design of optical, mechanical, and electrical systems, which could lead to highly sensitive and functionalized opto-electro-mechanical systems.

Process for predicting structural performance of mechanical systems

DOEpatents

Gardner, David R.; Hendrickson, Bruce A.; Plimpton, Steven J.; Attaway, Stephen W.; Heinstein, Martin W.; Vaughan, Courtenay T.

1998-01-01

A process for predicting the structural performance of a mechanical system represents the mechanical system by a plurality of surface elements. The surface elements are grouped according to their location in the volume occupied by the mechanical system so that contacts between surface elements can be efficiently located. The process is well suited for efficient practice on multiprocessor computers.

Integration mechanisms and hospital efficiency in integrated health care delivery systems.

PubMed

Wan, Thomas T H; Lin, Blossom Yen-Ju; Ma, Allen

2002-04-01

This study analyzes integration mechanisms that affect system performances measured by indicators of efficiency in integrated delivery systems (IDSs) in the United States. The research question is, do integration mechanisms improve IDSs' efficiency in hospital care? American Hospital Association's Annual Survey (1998) and Dorenfest's Survey on Information Systems in Integrated Healthcare Delivery Systems (1998) were used to conduct the study, using IDS as the unit of analysis. A covariance structure equation model of the effects of system integration mechanisms on IDS performance was formulated and validated by an empirical examination of IDSs. The study sample includes 973 hospital-based integrated health care delivery systems operating in the United States, carried in the list of Dorenfests Survey on Information Systems in Integrated Health care Delivery Systems. The measurement indicators of system integration mechanisms are categorized into six related domains: informatic integration, case management, hybrid physician-hospital integration, forward integration, backward integration, and high tech medical services. The multivariate analysis reveals that integration mechanisms in system operation are positively correlated and positively affect IDSs' efficiency. The six domains of integration mechanisms account for 58.9% of the total variance in hospital performance. The service differentiation strategy such as having more high tech medical services have much stronger influences on efficiency than other integration mechanisms do. The beneficial effects of integration mechanisms have been realized in IDS performance. High efficiency in hospital care can be achieved by employing proper integration strategies in operations.

Ovenized microelectromechanical system (MEMS) resonator

DOEpatents

Olsson, Roy H; Wojciechowski, Kenneth; Kim, Bongsang

2014-03-11

An ovenized micro-electro-mechanical system (MEMS) resonator including: a substantially thermally isolated mechanical resonator cavity; a mechanical oscillator coupled to the mechanical resonator cavity; and a heating element formed on the mechanical resonator cavity.

Identification of Bearing Failure Using Signal Vibrations

NASA Astrophysics Data System (ADS)

Yani, Irsyadi; Resti, Yulia; Burlian, Firmansyah

2018-04-01

Vibration analysis can be used to identify damage to mechanical systems such as journal bearings. Identification of failure can be done by observing the resulting vibration spectrum by measuring the vibration signal occurring in a mechanical system Bearing is one of the engine elements commonly used in mechanical systems. The main purpose of this research is to monitor the bearing condition and to identify bearing failure on a mechanical system by observing the resulting vibration. Data collection techniques based on recordings of sound caused by the vibration of the mechanical system were used in this study, then created a database system based bearing failure due to vibration signal recording sounds on a mechanical system The next step is to group the bearing damage by type based on the databases obtained. The results show the percentage of success in identifying bearing damage is 98 %.

Respiratory system dynamical mechanical properties: modeling in time and frequency domain.

PubMed

Carvalho, Alysson Roncally; Zin, Walter Araujo

2011-06-01

The mechanical properties of the respiratory system are important determinants of its function and can be severely compromised in disease. The assessment of respiratory system mechanical properties is thus essential in the management of some disorders as well as in the evaluation of respiratory system adaptations in response to an acute or chronic process. Most often, lungs and chest wall are treated as a linear dynamic system that can be expressed with differential equations, allowing determination of the system's parameters, which will reflect the mechanical properties. However, different models that encompass nonlinear characteristics and also multicompartments have been used in several approaches and most specifically in mechanically ventilated patients with acute lung injury. Additionally, the input impedance over a range of frequencies can be assessed with a convenient excitation method allowing the identification of the mechanical characteristics of the central and peripheral airways as well as lung periphery impedance. With the evolution of computational power, the airway pressure and flow can be recorded and stored for hours, and hence continuous monitoring of the respiratory system mechanical properties is already available in some mechanical ventilators. This review aims to describe some of the most frequently used models for the assessment of the respiratory system mechanical properties in both time and frequency domain.

Levers and linkages: mechanical trade-offs in a power-amplified system.

PubMed

Anderson, Philip S L; Claverie, Thomas; Patek, S N

2014-07-01

Mechanical redundancy within a biomechanical system (e.g., many-to-one mapping) allows morphologically divergent organisms to maintain equivalent mechanical outputs. However, most organisms depend on the integration of more than one biomechanical system. Here, we test whether coupled mechanical systems follow a pattern of amplification (mechanical changes are congruent and evolve toward the same functional extreme) or independence (mechanisms evolve independently). We examined the correlated evolution and evolutionary pathways of the coupled four-bar linkage and lever systems in mantis shrimp (Stomatopoda) ultrafast raptorial appendages. We examined models of character evolution in the framework of two divergent groups of stomatopods-"smashers" (hammer-shaped appendages) and "spearers" (bladed appendages). Smashers tended to evolve toward force amplification, whereas spearers evolved toward displacement amplification. These findings show that coupled biomechanical systems can evolve synergistically, thereby resulting in functional amplification rather than mechanical redundancy. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

Process for predicting structural performance of mechanical systems

DOEpatents

Gardner, D.R.; Hendrickson, B.A.; Plimpton, S.J.; Attaway, S.W.; Heinstein, M.W.; Vaughan, C.T.

1998-05-19

A process for predicting the structural performance of a mechanical system represents the mechanical system by a plurality of surface elements. The surface elements are grouped according to their location in the volume occupied by the mechanical system so that contacts between surface elements can be efficiently located. The process is well suited for efficient practice on multiprocessor computers. 12 figs.

46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Mechanical engine order telegraph systems; operation...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates a...

46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Mechanical engine order telegraph systems; operation...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates a...

46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Mechanical engine order telegraph systems; operation...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates a...

46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Mechanical engine order telegraph systems; operation...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates a...

Reintrepreting the cardiovascular system as a mechanical model

NASA Astrophysics Data System (ADS)

Lemos, Diogo; Machado, José; Minas, Graça; Soares, Filomena; Barros, Carla; Leão, Celina Pinto

2013-10-01

The simulation of the different physiological systems is very useful as a pedagogical tool, allowing a better understanding of the mechanisms and the functions of the processes. The observation of the physiological phenomena through mechanical simulators represents a great asset. Furthermore, the development of these simulators allows reinterpreting physiological systems, with the advantage of using the same transducers and sensors that are commonly used in diagnostic and therapeutic cardiovascular procedures for the monitoring of system' parameters. The cardiovascular system is one of the most important systems of the human body and has been the target of several biomedical studies. The present work describes a mechanical simulation of the cardiovascular system, in particularly, the systemic circulation, which can be described in terms of its hemodynamic variables. From the mechanical process and parameters, physiological system's behavior was reproduced, as accurately as possible.

Correlation of AO and Lauge-Hansen classification systems for ankle fractures to the mechanism of injury.

PubMed

Rodriguez, Edward K; Kwon, John Y; Herder, Lindsay M; Appleton, Paul T

2013-11-01

Our aim was to assess whether the Lauge-Hansen (LH) and the Muller AO classification systems for ankle fractures radiographically correlate with in vivo injuries based on observed mechanism of injury. Videos of potential study candidates were reviewed on YouTube.com. Individuals were recruited for participation if the video could be classified by injury mechanism with a high likelihood of sustaining an ankle fracture. Corresponding injury radiographs were obtained. Injury mechanism was classified using the LH system as supination/external rotation (SER), supination/adduction (SAD), pronation/external rotation (PER), or pronation/abduction (PAB). Corresponding radiographs were classified by the LH system and the AO system. Thirty injury videos with their corresponding radiographs were collected. Of the video clips reviewed, 16 had SAD mechanisms and 14 had PER mechanisms. There were 26 ankle fractures, 3 nonfractures, and 1 subtalar dislocation. Twelve fractures with SAD mechanisms had corresponding SAD fracture patterns. Five PER mechanisms had PER fracture patterns. Eight PER mechanisms had SER fracture patterns and 1 had SAD fracture pattern. When the AO classification was used, all 12 SAD type injuries had a 44A type fracture, whereas the 14 PER injuries resulted in nine 44B fractures, two 44C fractures, and three 43A fractures. When injury video clips of ankle fractures were matched to their corresponding radiographs, the LH system was 65% (17/26) consistent in predicting fracture patterns from the deforming injury mechanism. When the AO classification system was used, consistency was 81% (21/26). The AO classification, despite its development as a purely radiographic system, correlated with in vivo injuries, as based on observed mechanism of injury, more closely than did the LH system. Level IV, case series.

The Clementine mechanisms

NASA Technical Reports Server (NTRS)

Purdy, William; Hurley, Michael

1995-01-01

The Clementine spacecraft was developed under the 'faster, better, cheaper' theme. The constraints of a low budget coupled with an unusually tight schedule forced many departures from the normal spacecraft development methods. This paper discusses technical lessons learned about several of the mechanisms on the Clementine spacecraft as well as managerial lessons learned for the entire mechanisms subsystem. A quick overview of the Clementine mission is included; the mission schedule and environment during the mechanisms releases and deployment are highlighted. This paper then describes the entire mechanisms subsystem. The design and test approach and key philosophies for a fast-track program are discussed during the description of the mechanisms subsystem. The mechanism subsystem included a marman clamp separation system, a separation nut separation system, a solar panel deployment and pointing system, a high gain antenna feed deployment system, and two separate sensor cover systems. Each mechanism is briefly discussed. Additional technical discussion is given on the marman clamp design, the sensor cover designs, and the design and testing practices for systems driven by heated actuators (specifically paraffin actuators and frangibolts). All of the other mechanisms were of conventional designs and will receive less emphasis. Lessons learned are discussed throughout the paper as they applied to the systems being discussed. Since there is information on many different systems, this paper is organized so that information on a particular topic can be quickly referenced.

Aero-Mechanical Design Methodology for Subsonic Civil Transport High-Lift Systems

NASA Technical Reports Server (NTRS)

vanDam, C. P.; Shaw, S. G.; VanderKam, J. C.; Brodeur, R. R.; Rudolph, P. K. C.; Kinney, D.

2000-01-01

In today's highly competitive and economically driven commercial aviation market, the trend is to make aircraft systems simpler and to shorten their design cycle which reduces recurring, non-recurring and operating costs. One such system is the high-lift system. A methodology has been developed which merges aerodynamic data with kinematic analysis of the trailing-edge flap mechanism with minimum mechanism definition required. This methodology provides quick and accurate aerodynamic performance prediction for a given flap deployment mechanism early on in the high-lift system preliminary design stage. Sample analysis results for four different deployment mechanisms are presented as well as descriptions of the aerodynamic and mechanism data required for evaluation. Extensions to interactive design capabilities are also discussed.

Mechanisms for Robust Cognition.

PubMed

Walsh, Matthew M; Gluck, Kevin A

2015-08-01

To function well in an unpredictable environment using unreliable components, a system must have a high degree of robustness. Robustness is fundamental to biological systems and is an objective in the design of engineered systems such as airplane engines and buildings. Cognitive systems, like biological and engineered systems, exist within variable environments. This raises the question, how do cognitive systems achieve similarly high degrees of robustness? The aim of this study was to identify a set of mechanisms that enhance robustness in cognitive systems. We identify three mechanisms that enhance robustness in biological and engineered systems: system control, redundancy, and adaptability. After surveying the psychological literature for evidence of these mechanisms, we provide simulations illustrating how each contributes to robust cognition in a different psychological domain: psychomotor vigilance, semantic memory, and strategy selection. These simulations highlight features of a mathematical approach for quantifying robustness, and they provide concrete examples of mechanisms for robust cognition. © 2014 Cognitive Science Society, Inc.

Spline-Screw Multiple-Rotation Mechanism

NASA Technical Reports Server (NTRS)

Vranish, John M.

1994-01-01

Mechanism functions like combined robotic gripper and nut runner. Spline-screw multiple-rotation mechanism related to spline-screw payload-fastening system described in (GSC-13454). Incorporated as subsystem in alternative version of system. Mechanism functions like combination of robotic gripper and nut runner; provides both secure grip and rotary actuation of other parts of system. Used in system in which no need to make or break electrical connections to payload during robotic installation or removal of payload. More complicated version needed to make and break electrical connections. Mechanism mounted in payload.

Optimization of the Switch Mechanism in a Circuit Breaker Using MBD Based Simulation

PubMed Central

Jang, Jin-Seok; Yoon, Chang-Gyu; Ryu, Chi-Young; Kim, Hyun-Woo; Bae, Byung-Tae; Yoo, Wan-Suk

2015-01-01

A circuit breaker is widely used to protect electric power system from fault currents or system errors; in particular, the opening mechanism in a circuit breaker is important to protect current overflow in the electric system. In this paper, multibody dynamic model of a circuit breaker including switch mechanism was developed including the electromagnetic actuator system. Since the opening mechanism operates sequentially, optimization of the switch mechanism was carried out to improve the current breaking time. In the optimization process, design parameters were selected from length and shape of each latch, which changes pivot points of bearings to shorten the breaking time. To validate optimization results, computational results were compared to physical tests with a high speed camera. Opening time of the optimized mechanism was decreased by 2.3 ms, which was proved by experiments. Switch mechanism design process can be improved including contact-latch system by using this process. PMID:25918740

42 CFR 433.116 - FFP for operation of mechanized claims processing and information retrieval systems.

Code of Federal Regulations, 2011 CFR

2011-10-01

... and information retrieval systems. 433.116 Section 433.116 Public Health CENTERS FOR MEDICARE... FISCAL ADMINISTRATION Mechanized Claims Processing and Information Retrieval Systems § 433.116 FFP for operation of mechanized claims processing and information retrieval systems. (a) Subject to paragraph (j) of...

42 CFR 433.116 - FFP for operation of mechanized claims processing and information retrieval systems.

Code of Federal Regulations, 2013 CFR

2013-10-01

... and information retrieval systems. 433.116 Section 433.116 Public Health CENTERS FOR MEDICARE... FISCAL ADMINISTRATION Mechanized Claims Processing and Information Retrieval Systems § 433.116 FFP for operation of mechanized claims processing and information retrieval systems. (a) Subject to paragraph (j) of...

42 CFR 433.116 - FFP for operation of mechanized claims processing and information retrieval systems.

Code of Federal Regulations, 2014 CFR

2014-10-01

... and information retrieval systems. 433.116 Section 433.116 Public Health CENTERS FOR MEDICARE... FISCAL ADMINISTRATION Mechanized Claims Processing and Information Retrieval Systems § 433.116 FFP for operation of mechanized claims processing and information retrieval systems. (a) Subject to paragraph (j) of...

42 CFR 433.116 - FFP for operation of mechanized claims processing and information retrieval systems.

Code of Federal Regulations, 2012 CFR

2012-10-01

... and information retrieval systems. 433.116 Section 433.116 Public Health CENTERS FOR MEDICARE... FISCAL ADMINISTRATION Mechanized Claims Processing and Information Retrieval Systems § 433.116 FFP for operation of mechanized claims processing and information retrieval systems. (a) Subject to paragraph (j) of...

46 CFR 113.35-9 - Mechanical engine order telegraph systems.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Mechanical engine order telegraph systems. 113.35-9 Section 113.35-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-9 Mechanical engine order...

46 CFR 113.35-9 - Mechanical engine order telegraph systems.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Mechanical engine order telegraph systems. 113.35-9 Section 113.35-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-9 Mechanical engine order...

46 CFR 113.35-9 - Mechanical engine order telegraph systems.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Mechanical engine order telegraph systems. 113.35-9 Section 113.35-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-9 Mechanical engine order...

46 CFR 113.35-9 - Mechanical engine order telegraph systems.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Mechanical engine order telegraph systems. 113.35-9 Section 113.35-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-9 Mechanical engine order...

Spacecraft Maneuvering at the Sun/Earth-Moon L2 Libration Point

NASA Astrophysics Data System (ADS)

Shahid, Kamran

Spacecraft formation flying in the vicinity of the Sun/Earth-Moon libration points offers many promising possibilities for space exploration. The concept of formation flying involves the distribution of the functionality of a single spacecraft among several smaller, cooperative spacecraft. The libration points are locations relative to two large orbiting bodies where a third body with relatively small mass can remain stationary relative to the two larger bodies. The most significant perturbation experienced by a spacecraft at the libration point is effect of solar radiation pressure. This thesis presents the development of nonlinear control techniques for maneuvering control at the Sun-Earth/Moon L2 libration point. A new thruster based formation control technique is presented. We also consider a leader/follower formation architecture, and examine the station keeping control of the leader spacecraft and the formation control of the follower spacecraft using solar radiation pressure. Reference trajectories of the leader spacecraft, halo and Lissajous orbits, are determined using a numerical technique in order to take into account all major gravitational perturbations. The nonlinear controllers are developed based on Lyapunov analysis, including non-adaptive and adaptive designs. Thruster based and solar radiation pressure based control laws for spacecraft maneuvering at the Sun-Earth/Moon libration point are developed. Higher order sliding mode control is utilized to address the non-affine structure of the solar sail control inputs. The reduced input solar radiation pressure problem is properly addressed as an underactuated control problem. The development of adaptive control for solar sail equipped spacecraft is an innovation and represents and advancement in solar sailing control technology. Controller performance is evaluated in a high fidelity ephemeris model to reflect a realistic simulated space environment. The numerical results demonstrate the effectiveness of the proposed control techniques for spacecraft maneuvering using solar radiation pressure at the L2 libration point. Stationkeeping accuracies of 50m and formation maintenance accuracies of less than 1m are possible using solar radiation pressure at a sub-L2 libration point. The benefits of these control techniques include increasing libration point mission lifetimes and doubling payload mass fractions as compared to conventional propulsion methods.

Skinner-Rusk unified formalism for higher-order systems

NASA Astrophysics Data System (ADS)

Prieto-Martínez, Pedro Daniel; Román-Roy, Narciso

2012-07-01

The Lagrangian-Hamiltonian unified formalism of R. Skinner and R. Rusk was originally stated for autonomous dynamical systems in classical mechanics. It has been generalized for non-autonomous first-order mechanical systems, first-order and higher-order field theories, and higher-order autonomous systems. In this work we present a generalization of this formalism for higher-order non-autonomous mechanical systems.

42 CFR 433.116 - FFP for operation of mechanized claims processing and information retrieval systems.

Code of Federal Regulations, 2010 CFR

2010-10-01

... and information retrieval systems. 433.116 Section 433.116 Public Health CENTERS FOR MEDICARE... FISCAL ADMINISTRATION Mechanized Claims Processing and Information Retrieval Systems § 433.116 FFP for operation of mechanized claims processing and information retrieval systems. (a) Subject to 42 CFR 433.113(c...

The Conceptual Mechanism for Viable Organizational Learning Based on Complex System Theory and the Viable System Model

ERIC Educational Resources Information Center

Sung, Dia; You, Yeongmahn; Song, Ji Hoon

2008-01-01

The purpose of this research is to explore the possibility of viable learning organizations based on identifying viable organizational learning mechanisms. Two theoretical foundations, complex system theory and viable system theory, have been integrated to provide the rationale for building the sustainable organizational learning mechanism. The…

Collaboration Mechanism for Equipment Instruction of Multiple Energy Systems

NASA Astrophysics Data System (ADS)

Wang, Dong; Wang, Tuo; Wang, Qi; Zhang, Zhao; Zhao, Mingyu; Wang, Yinghui

2018-01-01

When multiple energy systems execute optimization instructions simultaneously, and the same equipment is Shared, the instruction conflict may occur. Aiming at the above problems, taking into account the control objectives of each system, the characteristics of different systems, such as comprehensive clean energy, energy efficiency, and peak filling, etc., designed the instruction coordination mechanism for the daemon. This mechanism mainly acts on the main station of the system, and form a final optimization instruction. For some specific scenarios, the collaboration mechanism of unlocking the terminal is supplemented. The mechanism determines the specific execution instructions based on the arrival time of the instruction. Finally, the experiment in Tianjin eco-city shows that this algorithm can meet the instruction and collaboration requirements of multi-energy systems, and ensure the safe operation of the equipment.

Lessons Learned From the Development, Operation, and Review of Mechanical Systems on the Space Shuttle, International Space Station, and Payloads

NASA Technical Reports Server (NTRS)

Dinsel, Alison; Jermstad, Wayne; Robertson, Brandan

2006-01-01

The Mechanical Design and Analysis Branch at the Johnson Space Center (JSC) is responsible for the technical oversight of over 30 mechanical systems flying on the Space Shuttle Orbiter and the International Space Station (ISS). The branch also has the responsibility for reviewing all mechanical systems on all Space Shuttle and International Space Station payloads, as part of the payload safety review process, through the Mechanical Systems Working Group (MSWG). These responsibilities give the branch unique insight into a large number of mechanical systems, and problems encountered during their design, testing, and operation. This paper contains narrative descriptions of lessons learned from some of the major problems worked on by the branch during the last two years. The problems are grouped into common categories and lessons learned are stated.

SMAP Instrument Mechanical System Engineering

NASA Technical Reports Server (NTRS)

Slimko, Eric; French, Richard; Riggs, Benjamin

2013-01-01

The Soil Moisture Active Passive (SMAP) mission, scheduled for launch by the end of 2014, is being developed to measure the soil moisture and soil freeze/thaw state on a global scale over a three-year period. The accuracy, resolution, and global coverage of SMAP measurements are invaluable across many science and applications disciplines including hydrology, climate, carbon cycle, and the meteorological, environment, and ecology applications communities. The SMAP observatory is composed of a despun bus and a spinning instrument platform that includes both a deployable 6 meter aperture low structural frequency Astromesh reflector and a spin control system. The instrument section has engendered challenging mechanical system issues associated with the antenna deployment, flexible antenna pointing in the context of a multitude of disturbances, spun section mass properties, spin control system development, and overall integration with the flight system on both mechanical and control system levels. Moreover, the multitude of organizations involved, including two major vendors providing the spin subsystem and reflector boom assembly plus the flight system mechanical and guidance, navigation, and control teams, has led to several unique system engineering challenges. Capturing the key physics associated with the function of the flight system has been challenging due to the many different domains that are applicable. Key interfaces and operational concepts have led to complex negotiations because of the large number of organizations that integrate with the instrument mechanical system. Additionally, the verification and validation concerns associated with the mechanical system have had required far-reaching involvement from both the flight system and other subsystems. The SMAP instrument mechanical systems engineering issues and their solutions are described in this paper.

Mechanical Systems Versus Smoking Bans for Secondhand Smoke Control

PubMed Central

Barrientos-Gutierrez, Tonatiuh; Amick, Benjamin C.; Gimeno, David; Reynales-Shigematsu, Luz M.; Delclos, George L.; Harrist, Ronald B.; Kelder, Steven H.; Lazcano-Ponce, Eduardo; Hernandez-Ávila, Mauricio

2012-01-01

Introduction: Despite international efforts to implement smoking bans, several national legislations still allow smoking and recommend mechanical systems, such as ventilation and air extraction, to eliminate secondhand smoke (SHS) health-related risks. We aimed to quantify the relative contribution of mechanical systems and smoking bans to SHS elimination. Methods: A cross-sectional study was conducted in randomly selected establishments from 4 Mexican cities (3 with no ban). SHS exposure was assessed using nicotine passive monitors. Establishment characteristics, presence of mechanical systems, and enforcement of smoking policies were obtained through direct observation and self-report. Multilevel models were used to assess relative contributions to SHS reduction. Results: Compared with Mexico City, nicotine concentrations were 3.8 times higher in Colima, 5.4 in Cuernavaca, and 6.4 in Toluca. Mechanical systems were not associated with reduced nicotine concentrations. Concentration differences between cities were largely explained by the presence of smoking bans (69.1% difference reduction) but not by mechanical systems (−5.7% difference reduction). Conclusions: Smoking bans represent the only effective approach to reduce SHS. Tobacco control regulations should stop considering mechanical systems as advisable means for SHS reduction and opt for complete smoking bans in public places. PMID:21994338

Lagrangian-Hamiltonian unified formalism for autonomous higher order dynamical systems

NASA Astrophysics Data System (ADS)

Prieto-Martínez, Pedro Daniel; Román-Roy, Narciso

2011-09-01

The Lagrangian-Hamiltonian unified formalism of Skinner and Rusk was originally stated for autonomous dynamical systems in classical mechanics. It has been generalized for non-autonomous first-order mechanical systems, as well as for first-order and higher order field theories. However, a complete generalization to higher order mechanical systems is yet to be described. In this work, after reviewing the natural geometrical setting and the Lagrangian and Hamiltonian formalisms for higher order autonomous mechanical systems, we develop a complete generalization of the Lagrangian-Hamiltonian unified formalism for these kinds of systems, and we use it to analyze some physical models from this new point of view.

Firmware Development Improves System Efficiency

NASA Technical Reports Server (NTRS)

Chern, E. James; Butler, David W.

1993-01-01

Most manufacturing processes require physical pointwise positioning of the components or tools from one location to another. Typical mechanical systems utilize either stop-and-go or fixed feed-rate procession to accomplish the task. The first approach achieves positional accuracy but prolongs overall time and increases wear on the mechanical system. The second approach sustains the throughput but compromises positional accuracy. A computer firmware approach has been developed to optimize this point wise mechanism by utilizing programmable interrupt controls to synchronize engineering processes 'on the fly'. This principle has been implemented in an eddy current imaging system to demonstrate the improvement. Software programs were developed that enable a mechanical controller card to transmit interrupts to a system controller as a trigger signal to initiate an eddy current data acquisition routine. The advantages are: (1) optimized manufacturing processes, (2) increased throughput of the system, (3) improved positional accuracy, and (4) reduced wear and tear on the mechanical system.

Common evolutionary trends underlie the four-bar linkage systems of sunfish and mantis shrimp.

PubMed

Hu, Yinan; Nelson-Maney, Nathan; Anderson, Philip S L

2017-05-01

Comparative biomechanics offers an opportunity to explore the evolution of disparate biological systems that share common underlying mechanics. Four-bar linkage modeling has been applied to various biological systems such as fish jaws and crustacean appendages to explore the relationship between biomechanics and evolutionary diversification. Mechanical sensitivity states that the functional output of a mechanical system will show differential sensitivity to changes in specific morphological components. We document similar patterns of mechanical sensitivity in two disparate four-bar systems from different phyla: the opercular four-bar system in centrarchid fishes and the raptorial appendage of stomatopods. We built dynamic linkage models of 19 centrarchid and 36 stomatopod species and used phylogenetic generalized least squares regression (PGLS) to compare evolutionary shifts in linkage morphology and mechanical outputs derived from the models. In both systems, the kinematics of the four-bar mechanism show significant evolutionary correlation with the output link, while travel distance of the output arm is correlated with the coupler link. This common evolutionary pattern seen in both fish and crustacean taxa is a potential consequence of the mechanical principles underlying four-bar systems. Our results illustrate the potential influence of physical principles on morphological evolution across biological systems with different structures, behaviors, and ecologies. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Lather (Interior Systems Mechanic). Occupational Analyses Series.

ERIC Educational Resources Information Center

Chapman, Mike; Chapman, Carol; MacLean, Margaret

This analysis covers tasks performed by a lather, an occupational title some provinces and territories of Canada have also identified as drywall and acoustical mechanic; interior systems installer; and interior systems mechanic. A guide to analysis discusses development, structure, and validation method; scope of the occupation; trends; and…

Mechanical Stimulation of Adipose-Derived Stem Cells for Functional Tissue Engineering of the Musculoskeletal System via Cyclic Hydrostatic Pressure, Simulated Microgravity, and Cyclic Tensile Strain.

PubMed

Nordberg, Rachel C; Bodle, Josie C; Loboa, Elizabeth G

2018-01-01

It is critical that human adipose stem cell (hASC) tissue-engineering therapies possess appropriate mechanical properties in order to restore function of the load bearing tissues of the musculoskeletal system. In an effort to elucidate the hASC response to mechanical stimulation and develop mechanically robust tissue engineered constructs, recent research has utilized a variety of mechanical loading paradigms including cyclic tensile strain, cyclic hydrostatic pressure, and mechanical unloading in simulated microgravity. This chapter describes methods for applying these mechanical stimuli to hASC to direct differentiation for functional tissue engineering of the musculoskeletal system.

Investigation of efficiency of electric drive control system of excavator traction mechanism based on feedback on load

NASA Astrophysics Data System (ADS)

Kuznetsov, N. K.; Iov, I. A.; Iov, A. A.

2018-05-01

The article presents the results of a study of the efficiency of the electric drive control system of the traction mechanism of a dragline based on the use of feedback on load in the traction cable. The investigations were carried out using a refined electromechanical model of the traction mechanism, which took into account not only the elastic elements of the gearbox, the backlashes in it and the changes in the kinematic parameters of the mechanism during operation, but also the mechanical characteristics of the electric drive and the features of its control system. By mathematical modeling of the transient processes of the electromechanical system, it is shown that the introduction of feedback on the load in the elastic element allows one to reduce the dynamic loads in the traction mechanism and to limit the elastic oscillations of the actuating mechanism in comparison with the standard control system. Fixed as a general decrease in the dynamic load of the nodes of traction mechanism in the modes of loading and latching of the bucket, and a decrease the operating time of the mechanism at maximum load. At the same time, undesirable phenomena in the operation of the electric drive were also associated with the increase in the recovery time of the steady-state value of the speed of the actuating mechanism under certain operating conditions, which can lead to a decrease in the reliability of the mechanical part and the productivity of the traction mechanism.

A Computer Code for Dynamic Stress Analysis of Media-Structure Problems with Nonlinearities (SAMSON). Volume III. User’s Manual.

DTIC Science & Technology

NONLINEAR SYSTEMS, LINEAR SYSTEMS, SUBROUTINES , SOIL MECHANICS, INTERFACES, DYNAMICS, LOADS(FORCES), FORCE(MECHANICS), DAMPING, ACCELERATION, ELASTIC...PROPERTIES, PLASTIC PROPERTIES, CRACKS , REINFORCING MATERIALS , COMPOSITE MATERIALS , FAILURE(MECHANICS), MECHANICAL PROPERTIES, INSTRUCTION MANUALS, DIGITAL COMPUTERS...STRESSES, *COMPUTER PROGRAMS), (*STRUCTURES, STRESSES), (*DATA PROCESSING, STRUCTURAL PROPERTIES), SOILS , STRAIN(MECHANICS), MATHEMATICAL MODELS

Give Better Feedback on Engineering Drawings

ERIC Educational Resources Information Center

Cobb, Robert, Jr.; Graham, Tony; Kapur, Arjun; Rhodes, Craig; Blackwell, Ellinor

2005-01-01

Most, if not all, systems have a mechanism that collects information to facilitate monitoring performance. This information is primarily used to modify the system to make it more efficient in performing desired tasks and, thus, attaining desired results. Similar to electrical, mechanical, or hydraulic systems, the feedback mechanism in an…

46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Mechanical engine order telegraph systems; operation. 113.35-13 Section 113.35-13 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED...-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates a...

A versatile nondestructive evaluation imaging workstation

NASA Technical Reports Server (NTRS)

Chern, E. James; Butler, David W.

1994-01-01

Ultrasonic C-scan and eddy current imaging systems are of the pointwise type evaluation systems that rely on a mechanical scanner to physically maneuver a probe relative to the specimen point by point in order to acquire data and generate images. Since the ultrasonic C-scan and eddy current imaging systems are based on the same mechanical scanning mechanisms, the two systems can be combined using the same PC platform with a common mechanical manipulation subsystem and integrated data acquisition software. Based on this concept, we have developed an IBM PC-based combined ultrasonic C-scan and eddy current imaging system. The system is modularized and provides capacity for future hardware and software expansions. Advantages associated with the combined system are: (1) eliminated duplication of the computer and mechanical hardware, (2) unified data acquisition, processing and storage software, (3) reduced setup time for repetitious ultrasonic and eddy current scans, and (4) improved system efficiency. The concept can be adapted to many engineering systems by integrating related PC-based instruments into one multipurpose workstation such as dispensing, machining, packaging, sorting, and other industrial applications.

Coupled dynamics of a viscoelastically supported infinite string and a number of discrete mechanical systems moving with uniform speed

NASA Astrophysics Data System (ADS)

Roy, Soumyajit; Chakraborty, G.; DasGupta, Anirvan

2018-02-01

The mutual interaction between a number of multi degrees of freedom mechanical systems moving with uniform speed along an infinite taut string supported by a viscoelastic layer has been studied using the substructure synthesis method when base excitations of a common frequency are given to the mechanical systems. The mobility or impedance matrices of the string have been calculated analytically by Fourier transform method as well as wave propagation technique. The above matrices are used to calculate the response of the discrete mechanical systems. Special attention is paid to the contact forces between the discrete and the continuous systems which are estimated by numerical simulation. The effects of phase difference, the distance between the systems and different base excitation amplitudes on the collective behaviour of the mechanical systems are also studied. The present study has relevance to the coupled dynamic problem of more than one railway pantographs and an overhead catenary system where the pantographs are modelled as discrete systems and the catenary is modelled as a taut string supported by continuous viscoelastic layer.

A versatile nondestructive evaluation imaging workstation

NASA Astrophysics Data System (ADS)

Chern, E. James; Butler, David W.

1994-02-01

Ultrasonic C-scan and eddy current imaging systems are of the pointwise type evaluation systems that rely on a mechanical scanner to physically maneuver a probe relative to the specimen point by point in order to acquire data and generate images. Since the ultrasonic C-scan and eddy current imaging systems are based on the same mechanical scanning mechanisms, the two systems can be combined using the same PC platform with a common mechanical manipulation subsystem and integrated data acquisition software. Based on this concept, we have developed an IBM PC-based combined ultrasonic C-scan and eddy current imaging system. The system is modularized and provides capacity for future hardware and software expansions. Advantages associated with the combined system are: (1) eliminated duplication of the computer and mechanical hardware, (2) unified data acquisition, processing and storage software, (3) reduced setup time for repetitious ultrasonic and eddy current scans, and (4) improved system efficiency. The concept can be adapted to many engineering systems by integrating related PC-based instruments into one multipurpose workstation such as dispensing, machining, packaging, sorting, and other industrial applications.

UNIX security in a supercomputing environment

NASA Technical Reports Server (NTRS)

Bishop, Matt

1989-01-01

The author critiques some security mechanisms in most versions of the Unix operating system and suggests more effective tools that either have working prototypes or have been implemented, for example in secure Unix systems. Although no computer (not even a secure one) is impenetrable, breaking into systems with these alternate mechanisms will cost more, require more skill, and be more easily detected than penetrations of systems without these mechanisms. The mechanisms described fall into four classes (with considerable overlap). User authentication at the local host affirms the identity of the person using the computer. The principle of least privilege dictates that properly authenticated users should have rights precisely sufficient to perform their tasks, and system administration functions should be compartmentalized; to this end, access control lists or capabilities should either replace or augment the default Unix protection system, and mandatory access controls implementing multilevel security models and integrity mechanisms should be available. Since most users access supercomputing environments using networks, the third class of mechanisms augments authentication (where feasible). As no security is perfect, the fourth class of mechanism logs events that may indicate possible security violations; this will allow the reconstruction of a successful penetration (if discovered), or possibly the detection of an attempted penetration.

Optical spring effect in nanoelectromechanical systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Feng; Zhou, Guangya, E-mail: mpezgy@nus.edu.sg; Du, Yu

2014-08-11

In this Letter, we report a hybrid system consisting of nano-optical and nano-mechanical springs, in which the optical spring effect works to adjust the mechanical frequency of a nanoelectromechanical systems resonator. Nano-scale folded beams are fabricated as the mechanical springs and double-coupled one-dimensional photonic crystal cavities are used to pump the “optical spring.” The dynamic characteristics of this hybrid system are measured and analyzed at both low and high input optical powers. This study leads the physical phenomenon of optomechanics in complex nano-opto-electro-mechanical systems (NOEMS) and could benefit the future applications of NOEMS in chip-level communication and sensing.

Acoustic relaxation of the hydro-mechanical system under critical expiration of swirl flow

NASA Astrophysics Data System (ADS)

Pozdeeva, I. G.; Mitrofanova, O. V.

2018-03-01

The mechanism of generation of acoustic oscillations associated with the formation of stable vortex structures in the moving fluid was considered for the impact swirl flow. Experimental studies were carried out to determine the relationship between large-scale vortex motion and acoustic effects in hydro-mechanical systems. It was shown that a sharp change of the amplitude-frequency characteristic of the acoustic oscillations of hydro-mechanical system corresponds to the maximal flow rate of the swirl flow. The established connection between the generation of sound waves and geometrical and regime parameters of the hydro-mechanical system formed the basis for the developed method of diagnostics of the processes of vortex formation.

Steady-state mechanical squeezing and ground-state cooling of a Duffing anharmonic oscillator in an optomechanical cavity assisted by a nonlinear medium

NASA Astrophysics Data System (ADS)

Momeni, F.; Naderi, M. H.

2018-05-01

In this paper, we study theoretically a hybrid optomechanical system consisting of a degenerate optical parametric amplifier inside a driven optical cavity with a moving end mirror which is modeled as a stiffening Duffing-like anharmonic quantum mechanical oscillator. By providing analytical expressions for the critical values of the system parameters corresponding to the emergence of the multistability behavior in the steady-state response of the system, we show that the stiffening mechanical Duffing anharmonicity reduces the width of the multistability region while the optical parametric nonlinearity can be exploited to drive the system toward the multistability region. We also show that for appropriate values of the mechanical anharmonicity strength the steady-state mechanical squeezing and the ground-state cooling of the mechanical resonator can be achieved. Moreover, we find that the presence of the nonlinear gain medium can lead to the improvement of the mechanical anharmonicity-induced cooling of the mechanical motion, as well as to the mechanical squeezing beyond the standard quantum limit of 3 dB.

Evidence-based selection of training compounds for use in the mechanism-based integrated prediction of drug-induced liver injury in man.

PubMed

Dragovic, Sanja; Vermeulen, Nico P E; Gerets, Helga H; Hewitt, Philip G; Ingelman-Sundberg, Magnus; Park, B Kevin; Juhila, Satu; Snoeys, Jan; Weaver, Richard J

2016-12-01

The current test systems employed by pharmaceutical industry are poorly predictive for drug-induced liver injury (DILI). The 'MIP-DILI' project addresses this situation by the development of innovative preclinical test systems which are both mechanism-based and of physiological, pharmacological and pathological relevance to DILI in humans. An iterative, tiered approach with respect to test compounds, test systems, bioanalysis and systems analysis is adopted to evaluate existing models and develop new models that can provide validated test systems with respect to the prediction of specific forms of DILI and further elucidation of mechanisms. An essential component of this effort is the choice of compound training set that will be used to inform refinement and/or development of new model systems that allow prediction based on knowledge of mechanisms, in a tiered fashion. In this review, we focus on the selection of MIP-DILI training compounds for mechanism-based evaluation of non-clinical prediction of DILI. The selected compounds address both hepatocellular and cholestatic DILI patterns in man, covering a broad range of pharmacologies and chemistries, and taking into account available data on potential DILI mechanisms (e.g. mitochondrial injury, reactive metabolites, biliary transport inhibition, and immune responses). Known mechanisms by which these compounds are believed to cause liver injury have been described, where many if not all drugs in this review appear to exhibit multiple toxicological mechanisms. Thus, the training compounds selection offered a valuable tool to profile DILI mechanisms and to interrogate existing and novel in vitro systems for the prediction of human DILI.

Feasibility of Using Neural Network Models to Accelerate the Testing of Mechanical Systems

NASA Technical Reports Server (NTRS)

Fusaro, Robert L.

1998-01-01

Verification testing is an important aspect of the design process for mechanical mechanisms, and full-scale, full-length life testing is typically used to qualify any new component for use in space. However, as the required life specification is increased, full-length life tests become more costly and lengthen the development time. At the NASA Lewis Research Center, we theorized that neural network systems may be able to model the operation of a mechanical device. If so, the resulting neural network models could simulate long-term mechanical testing with data from a short-term test. This combination of computer modeling and short-term mechanical testing could then be used to verify the reliability of mechanical systems, thereby eliminating the costs associated with long-term testing. Neural network models could also enable designers to predict the performance of mechanisms at the conceptual design stage by entering the critical parameters as input and running the model to predict performance. The purpose of this study was to assess the potential of using neural networks to predict the performance and life of mechanical systems. To do this, we generated a neural network system to model wear obtained from three accelerated testing devices: 1) A pin-on-disk tribometer; 2) A line-contact rub-shoe tribometer; 3) A four-ball tribometer.

Design of mechanical arm for an automatic sorting system of recyclable cans

NASA Astrophysics Data System (ADS)

Resti, Y.; Mohruni, A. S.; Burlian, F.; Yani, I.; Amran, A.

2018-04-01

The use of a mechanical arm for an automatic sorting system of used cans should be designed carefully. The right design will result in a high precision sorting rate and a short sorting time. The design includes first; design manipulator,second; determine link and joint specifications, and third; build mechanical systems and control systems. This study aims to design the mechanical arm as a hardware system for automatic cans sorting system. The material used for the manipulator is the aluminum plate. The manipulator is designed using 6 links and 6 join where the 6th link is the end effectorand the 6th join is the gripper. As a driving motor used servo motor, while as a microcontroller used Arduino Uno which is connected with Matlab programming language. Based on testing, a mechanical arm designed for this recyclable canned recycling system has a precision sorting rate at 93%, where the average total time required for sorting is 10.82 seconds.

[The respiratory system--its self-cleaning system. General mechanisms of clearance].

PubMed

Mustajbegović, J; Zuskin, E

1998-01-01

The behaviour of particles and deposition in different parts of respiratory system are described. Listed are factors which contribute to the deposition of particles in the lungs and upper areas of the respiratory system. The general mechanisms of lung clearance and their action such as cough, mucociliary transport, alveolar clearance and immunological system are reported. Particularly is stressed the necessity of coordination of all defense mechanisms in order to maintain normal respiratory function.

Lather-Interior Systems Mechanic: Apprenticeship Course Outline. Apprenticeship and Industry Training. 1709

ERIC Educational Resources Information Center

Alberta Advanced Education and Technology, 2009

2009-01-01

The graduate of the Lather-Interior Systems Mechanic apprenticeship program is a certified journeyperson who will be able to: (1) know the characteristics and understand the actions and interactions of Lathing and Interior Systems Mechanic materials; (2) interpret plans and specifications and layout and develop projects accordingly; (3) calculate…

14 CFR 27.923 - Rotor drive system and control mechanism tests.

Code of Federal Regulations, 2010 CFR

2010-01-01

... the position that will give maximum longitudinal cyclic pitch change to simulate forward flight. The... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Rotor drive system and control mechanism....923 Rotor drive system and control mechanism tests. (a) Each part tested as prescribed in this section...

The Roles of Mental Animations and External Animations in Understanding Mechanical Systems

ERIC Educational Resources Information Center

Hegarty, Mary; Kriz, Sarah; Cate, Christina

2003-01-01

The effects of computer animations and mental animation on people's mental models of a mechanical system are examined. In 3 experiments, students learned how a mechanical system works from various instructional treatments including viewing a static diagram of the machine, predicting motion from static diagrams, viewing computer animations, and…

Multimedia-assisted breathwalk-aware system.

PubMed

Yu, Meng-Chieh; Wu, Huan; Lee, Ming-Sui; Hung, Yi-Ping

2012-12-01

Breathwalk is a science of combining specific patterns of footsteps synchronized with the breathing. In this study, we developed a multimedia-assisted Breathwalk-aware system which detects user's walking and breathing conditions and provides appropriate multimedia guidance on the smartphone. Through the mobile device, the system enhances user's awareness of walking and breathing behaviors. As an example application in slow technology, the system could help meditator beginners learn "walking meditation," a type of meditation which aims to be as slow as possible in taking pace, to synchronize footstep with breathing, and to land every footstep with toes first. In the pilot study, we developed a walking-aware system and evaluated whether multimedia-assisted mechanism is capable of enhancing beginner's walking awareness while walking meditation. Experimental results show that it could effectively assist beginners in slowing down the walking speed and decreasing incorrect footsteps. In the second experiment, we evaluated the Breathwalk-aware system to find a better feedback mechanism for learning the techniques of Breathwalk while walking meditation. The experimental results show that the visual-auditory mechanism is a better multimedia-assisted mechanism while walking meditation than visual mechanism and auditory mechanism.

49 CFR 236.102 - Semaphore or searchlight signal mechanism.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Semaphore or searchlight signal mechanism. 236.102... Instructions: All Systems Inspections and Tests; All Systems § 236.102 Semaphore or searchlight signal mechanism. (a) Semaphore signal mechanism shall be inspected at least once every six months, and tests of...

Performance evaluation of the machine learning algorithms used in inference mechanism of a medical decision support system.

PubMed

Bal, Mert; Amasyali, M Fatih; Sever, Hayri; Kose, Guven; Demirhan, Ayse

2014-01-01

The importance of the decision support systems is increasingly supporting the decision making process in cases of uncertainty and the lack of information and they are widely used in various fields like engineering, finance, medicine, and so forth, Medical decision support systems help the healthcare personnel to select optimal method during the treatment of the patients. Decision support systems are intelligent software systems that support decision makers on their decisions. The design of decision support systems consists of four main subjects called inference mechanism, knowledge-base, explanation module, and active memory. Inference mechanism constitutes the basis of decision support systems. There are various methods that can be used in these mechanisms approaches. Some of these methods are decision trees, artificial neural networks, statistical methods, rule-based methods, and so forth. In decision support systems, those methods can be used separately or a hybrid system, and also combination of those methods. In this study, synthetic data with 10, 100, 1000, and 2000 records have been produced to reflect the probabilities on the ALARM network. The accuracy of 11 machine learning methods for the inference mechanism of medical decision support system is compared on various data sets.

45 CFR 205.35 - Mechanized claims processing and information retrieval systems; definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... claims processing and information retrieval systems; definitions. Section 205.35 through 205.38 contain...: (a) A mechanized claims processing and information retrieval system, hereafter referred to as an automated application processing and information retrieval system (APIRS), or the system, means a system of...

45 CFR 205.35 - Mechanized claims processing and information retrieval systems; definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... claims processing and information retrieval systems; definitions. Section 205.35 through 205.38 contain...: (a) A mechanized claims processing and information retrieval system, hereafter referred to as an automated application processing and information retrieval system (APIRS), or the system, means a system of...

45 CFR 205.35 - Mechanized claims processing and information retrieval systems; definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... claims processing and information retrieval systems; definitions. Section 205.35 through 205.38 contain...: (a) A mechanized claims processing and information retrieval system, hereafter referred to as an automated application processing and information retrieval system (APIRS), or the system, means a system of...

Research on the content framework of information disclosure mechanism in Shanxi power market

NASA Astrophysics Data System (ADS)

Sun, Yanzhang; Li, Tao; Hou, Zhehui; Cao, Xiaozhong

2018-06-01

With the further development of the power reform, establishing a sound power system with rich content and efficient operation has become an urgent need. Faced with the current circumstance of power market information disclosure in Shanxi province, this paper fully incorporates the actual situation and introduces the index into the power market information disclosure mechanism, and sets up the general information disclosure framework in Shanxi province power market on the basis of which A direct information disclosure mechanism and an indirect information disclosure mechanism were designed. Then we formulate comprehensive power index system, generation index system, transmission and distribution index system, and power utilization index system. In conclusion, the outcomes above will enrich power information disclosure mechanism in Shanxi province and will provide a platform for various market members as a guidance on setting right business decisions.

Macroscopic Entangled State Generation with Optomechanical Coupling of Two Mechanical Modes

NASA Astrophysics Data System (ADS)

Weaver, Matthew; Luna, Fernando; Buters, Frank; Heeck, Kier; de Man, Sven; Bouwmeester, Dirk

Mechanical resonators with a large quantum position uncertainty are an excellent test system for proposed decoherence mechanisms in massive systems. We present a scheme to optomechanically entangle two mechanical resonators with large frequency separation via two tone driving and single photon projection measurements. The quantum position uncertainty can be tuned with a variable optical pulse displacement operation, and independent single photon readout of the two resonators provides robust verification of the quantum states of the system. This scheme is currently experimentally feasible in a number of high mass opto- and electro-mechanical systems. We demonstrate one such system with two spatially and frequency separated Si3N4 trampoline resonators. We also show how the resonators can be coupled with two tone driving and the single photon optomechanical coupling rates can be tuned.

A system-level mathematical model for evaluation of power train performance of load-leveled electric-vehicles

NASA Technical Reports Server (NTRS)

Purohit, G. P.; Leising, C. J.

1984-01-01

The power train performance of load leveled electric vehicles can be compared with that of nonload leveled systems by use of a simple mathematical model. This method of measurement involves a number of parameters including the degree of load leveling and regeneration, the flywheel mechanical to electrical energy fraction, and efficiencies of the motor, generator, flywheel, and transmission. Basic efficiency terms are defined and representative comparisons of a variety of systems are presented. Results of the study indicate that mechanical transfer of energy into and out of the flywheel is more advantageous than electrical transfer. An optimum degree of load leveling may be achieved in terms of the driving cycle, battery characteristics, mode of mechanization, and the efficiency of the components. For state of the art mechanically coupled flyheel systems, load leveling losses can be held to a reasonable 10%; electrically coupled systems can have losses that are up to six times larger. Propulsion system efficiencies for mechanically coupled flywheel systems are predicted to be approximately the 60% achieved on conventional nonload leveled systems.

Neural Network Models of Simple Mechanical Systems Illustrating the Feasibility of Accelerated Life Testing

NASA Technical Reports Server (NTRS)

Fusaro, Robert L.; Jones, Steven P.; Jansen, Ralph

1996-01-01

A complete evaluation of the tribological characteristics of a given material/mechanical system is a time-consuming operation since the friction and wear process is extremely systems sensitive. As a result, experimental designs (i.e., Latin Square, Taguchi) have been implemented in an attempt to not only reduce the total number of experimental combinations needed to fully characterize a material/mechanical system, but also to acquire life data for a system without having to perform an actual life test. Unfortunately, these experimental designs still require a great deal of experimental testing and the output does not always produce meaningful information. In order to further reduce the amount of experimental testing required, this study employs a computer neural network model to investigate different material/mechanical systems. The work focuses on the modeling of the wear behavior, while showing the feasibility of using neural networks to predict life data. The model is capable of defining which input variables will influence the tribological behavior of the particular material/mechanical system being studied based on the specifications of the overall system.

Steady-State Solutions Originating from an Enhanced Nonlinear Feedback in a Hybrid Opto-mechanical System

NASA Astrophysics Data System (ADS)

Fan, Qiu-Bo; Wang, Yi-Ru; Chen, Jin; Pan, Yue-Wu; Han, Bai-Ping; Fu, Chang-Bao; Sun, Yan

2017-06-01

The steady-state properties of a hybrid system are investigated in this paper. Many cold atoms in the four-level tripod configuration are confined in an optical cavity with a movable end mirror. The confined cold atoms are driven with two external classical fields and an internal cavity field. The internal cavity field is excited by an external driving field and shows a radiation pressure upon the movable end mirror. The coupling of atom-light and opto-mechanical interactions is enhanced by embedding a four-level atomic system in a typical opto-mechanical cavity. And an enhanced nonlinear feedback mechanism is offered by the enhanced coupling, which permits the observation of five and three steady-state solutions for relevant variables near two-photon resonance. The enhanced nonlinear feedback mechanism also allows us to observe the obvious difference in the double-EIT phenomenon between the atom-assisted opto-mechanical system and usual atom-field system.

Aligned Carbon Nanotube Carpets on Carbon Substrates for High Power Electronic Applications

DTIC Science & Technology

2016-06-01

SiOx by a vapor-solid-solid mechanism ,” J. Am. Chem. Soc., vol. 133, pp. 197–199, 2011. [146] B. Liu, W. Ren, C. Liu, C.-H. Sun , L. Gao, S. Li, C... Mechanical and Thermal Systems Branch Power and Control Division JUNE 2016 Interim Report DISTRIBUTION STATEMENT A: Approved for public release...Advisor Program Engineer Mechanical and Thermal Systems Branch Mechanical and Thermal Systems Branch Power and Control Division Power and Control

Microgravity experiments of nano-satellite docking mechanism for final rendezvous approach and docking phase

NASA Astrophysics Data System (ADS)

Ui, Kyoichi; Matunaga, Saburo; Satori, Shin; Ishikawa, Tomohiro

2005-09-01

Laboratory for Space Systems (LSS), Tokyo Institute of Technology (Tokyo Tech) conducted three-dimensional microgravity environment experiments about a docking mechanism for mothership-daughtership (MS-DS) nano-satellite using the facility of Japan Micro Gravity Center (JAMIC) with Hokkaido Institute of Technology (HIT). LSS has studied and developed a docking mechanism for MS-DS nano-satellite system in final rendezvous approach and docking phase since 2000. Consideration of the docking mechanism is to mate a nano-satellite stably while remaining control error of relative velocity and attitude because it is difficult for nano-satellite to have complicated attitude control and mating systems. Objective of the experiments is to verify fundamental grasping function based on our proposed docking methodology. The proposed docking sequence is divided between approach/grasping phase and guiding phase. In the approach/grasping phase, the docking mechanism grasps the nano-satellite even though the nano-satellite has relative position and attitude control errors as well as relative velocity in a docking space. In the guiding function, the docking mechanism guides the nano-satellite to a docking port while adjusting its attitude in order to transfer electrical power and fuel to the nano-satellite. In the paper, we describe the experimental system including the docking mechanism, control system, the daughtership system and the release mechanism, and describe results of microgravity experiments in JAMIC.

Unified formalism for higher order non-autonomous dynamical systems

NASA Astrophysics Data System (ADS)

Prieto-Martínez, Pedro Daniel; Román-Roy, Narciso

2012-03-01

This work is devoted to giving a geometric framework for describing higher order non-autonomous mechanical systems. The starting point is to extend the Lagrangian-Hamiltonian unified formalism of Skinner and Rusk for these kinds of systems, generalizing previous developments for higher order autonomous mechanical systems and first-order non-autonomous mechanical systems. Then, we use this unified formulation to derive the standard Lagrangian and Hamiltonian formalisms, including the Legendre-Ostrogradsky map and the Euler-Lagrange and the Hamilton equations, both for regular and singular systems. As applications of our model, two examples of regular and singular physical systems are studied.

Analysis of hydraulic steering system of tracked all-terrain vehicles' articulated mechanism

NASA Astrophysics Data System (ADS)

Meng, Zhongliang; Zang, Hao

2018-04-01

As for the researches on the dynamic characteristics of tracked all-terrain vehicles' articulated mechanism, the hydraulic feature of their steering system needs researching more, apart from the study on mechanical models. According to the maximum pressure required by the steering system of tracked all-terrain vehicle and the principle of the steering system, this paper conducts an analysis of the hydraulic steering system of the articulated mechanism. Based on the structure principle of the steering gear, a simulation model of the tracked all-terrain vehicle turning left is built. When building the simulation model of the steering gear, it makes a simulation analysis, taking the tracked all-terrain vehicle turning left as an example.

Energetic composite and system with enhanced mechanical sensitivity to initiation of self-sustained reaction

DOEpatents

Gash, Alexander E [Brentwood, CA; Barbee, Jr., Troy W.

2012-05-29

An energetic composition and system using amassed energetic multilayer pieces which are formed from the division, such as for example by cutting, scoring, breaking, crushing, shearing, etc., of a mechanically activatable monolithic energetic multilayer(s) (e.g. macro-scale sheets of multilayer films), for enhancing the sensitivity of the energetic composite and system to mechanical initiation of self-sustained reaction. In particular, mechanical initiation of the energetic composition may be achieved with significantly lower mechanical energy inputs than that typically required for initiating the monolithic energetic multilayers from which it is derived.

Compendium of Mechanical Limit-States

NASA Technical Reports Server (NTRS)

Kowal, Michael

1996-01-01

A compendium was compiled and is described to provide a diverse set of limit-state relationships for use in demonstrating the application of probabilistic reliability methods to mechanical systems. The different limit-state relationships can be used to analyze the reliability of a candidate mechanical system. In determining the limit-states to be included in the compendium, a comprehensive listing of the possible failure modes that could affect mechanical systems reliability was generated. Previous literature defining mechanical modes of failure was studied, and cited failure modes were included. From this, classifications for failure modes were derived and are described in some detail.

Mechanical code comparator

DOEpatents

Peter, Frank J.; Dalton, Larry J.; Plummer, David W.

2002-01-01

A new class of mechanical code comparators is described which have broad potential for application in safety, surety, and security applications. These devices can be implemented as micro-scale electromechanical systems that isolate a secure or otherwise controlled device until an access code is entered. This access code is converted into a series of mechanical inputs to the mechanical code comparator, which compares the access code to a pre-input combination, entered previously into the mechanical code comparator by an operator at the system security control point. These devices provide extremely high levels of robust security. Being totally mechanical in operation, an access control system properly based on such devices cannot be circumvented by software attack alone.

Stray light suppression of optical and mechanical system for telescope detection

NASA Astrophysics Data System (ADS)

Wang, Lei; Ma, Wenli

2013-09-01

During telescope detection, there is atmosphere overflow and other stray light affecting the system which leads to background disturbance. Thus reduce the detection capability of the system. So it is very necessary to design mechanical structure to suppress the stray light for the telescope detection system. It can both improve the signal-to-noise and contrast of the object. This paper designs the optical and mechanical structure of the 400mm telescope. And then the main baffle, baffle vane, field stop and coating technology are used to eliminate the effect of stray light on the optical and mechanical system. Finally, software is used to analyze and simulate stray light on the whole optical and mechanical system. Using PST as the evaluating standard, separate and integrated analysis of the suppressing effect of main baffle, baffle vane and field aperture is completed. And also get the results of PST before and after eliminating the stray light. Meanwhile, the results of stray light analysis can be used to guide the design of the optical and mechanical structure. The analysis results demonstrate that reasonable optical and mechanical structure and stray light suppression measure can highly reduce the PST and also improve the detection capability of the telescope system, and the designed outside baffle, inside baffle, vanes and coating technique etc. can decrease the PST approximately 1 to 3 level.

The role of mechanics in biological and bio-inspired systems.

PubMed

Egan, Paul; Sinko, Robert; LeDuc, Philip R; Keten, Sinan

2015-07-06

Natural systems frequently exploit intricate multiscale and multiphasic structures to achieve functionalities beyond those of man-made systems. Although understanding the chemical make-up of these systems is essential, the passive and active mechanics within biological systems are crucial when considering the many natural systems that achieve advanced properties, such as high strength-to-weight ratios and stimuli-responsive adaptability. Discovering how and why biological systems attain these desirable mechanical functionalities often reveals principles that inform new synthetic designs based on biological systems. Such approaches have traditionally found success in medical applications, and are now informing breakthroughs in diverse frontiers of science and engineering.

42 CFR 433.112 - FFP for design, development, installation or enhancement of mechanized claims processing and...

Code of Federal Regulations, 2014 CFR

2014-10-01

... enhancement of mechanized claims processing and information retrieval systems. 433.112 Section 433.112 Public... processing and information retrieval systems. (a) Subject to paragraph (c) of this section, FFP is available... enhancement of a mechanized claims processing and information retrieval system only if the APD is approved by...

42 CFR 433.112 - FFP for design, development, installation or enhancement of mechanized claims processing and...

Code of Federal Regulations, 2012 CFR

2012-10-01

... enhancement of mechanized claims processing and information retrieval systems. 433.112 Section 433.112 Public... processing and information retrieval systems. (a) Subject to paragraph (c) of this section, FFP is available... enhancement of a mechanized claims processing and information retrieval system only if the APD is approved by...

42 CFR 433.112 - FFP for design, development, installation or enhancement of mechanized claims processing and...

Code of Federal Regulations, 2011 CFR

2011-10-01

... enhancement of mechanized claims processing and information retrieval systems. 433.112 Section 433.112 Public... processing and information retrieval systems. (a) Subject to paragraph (c) of this section, FFP is available... enhancement of a mechanized claims processing and information retrieval system only if the APD is approved by...

42 CFR 433.112 - FFP for design, development, installation or enhancement of mechanized claims processing and...

Code of Federal Regulations, 2013 CFR

2013-10-01

... enhancement of mechanized claims processing and information retrieval systems. 433.112 Section 433.112 Public... processing and information retrieval systems. (a) Subject to paragraph (c) of this section, FFP is available... enhancement of a mechanized claims processing and information retrieval system only if the APD is approved by...

Application of the luciferin-luciferase enzyme system for determination of adenosine triphosphate (ATP) to studies on the mechanisms of herbicide action

NASA Technical Reports Server (NTRS)

St.john, J. B.

1975-01-01

The luciferin-luciferase enzyme system for determination of ATP is valuable for studies on the mechanisms of herbicide action. Investigations using this system have shown that certain herbicides may act by interfering with ATP production or by blocking ATP use, or by both mechanisms.

Bacterial Translocation Ratchets: Shared Physical Principles with Different Molecular Implementations: How bacterial secretion systems bias Brownian motion for efficient translocation of macromolecules.

PubMed

Hepp, Christof; Maier, Berenike

2017-10-01

Secretion systems enable bacteria to import and secrete large macromolecules including DNA and proteins. While most components of these systems have been identified, the molecular mechanisms of macromolecular transport remain poorly understood. Recent findings suggest that various bacterial secretion systems make use of the translocation ratchet mechanism for transporting polymers across the cell envelope. Translocation ratchets are powered by chemical potential differences generated by concentration gradients of ions or molecules that are specific to the respective secretion systems. Bacteria employ these potential differences for biasing Brownian motion of the macromolecules within the conduits of the secretion systems. Candidates for this mechanism include DNA import by the type II secretion/type IV pilus system, DNA export by the type IV secretion system, and protein export by the type I secretion system. Here, we propose that these three secretion systems employ different molecular implementations of the translocation ratchet mechanism. © 2017 The Authors. BioEssays Published by WILEY Periodicals, Inc.

The 18th Aerospace Mechanisms Symposium

NASA Technical Reports Server (NTRS)

1984-01-01

Topics concerning aerospace mechanisms, their functional performance, and design specifications are presented. Discussed subjects include the design and development of release mechanisms, actuators, linear driver/rate controllers, antenna and appendage deployment systems, position control systems, and tracking mechanisms for antennas and solar arrays. Engine design, spaceborne experiments, and large space structure technology are also examined.

The Construction of an Online Competitive Game-Based Learning System for Junior High School Students

ERIC Educational Resources Information Center

Cheng, Yuh-Ming; Kuo, Sheng-Huang; Lou, Shi-Jer; Shih, Ru-Chu

2012-01-01

The purpose of this study aimed to construct an online competitive game-based learning system by using freeware for junior high school students and to assess its effectiveness. From the learning standpoints, game mechanisms including learning points, competition mechanism, training room mechanism, questioning & answering mechanism, tips, and…

Hydraulic elements in reduction of vibrations in mechanical systems

NASA Astrophysics Data System (ADS)

Białas, K.; Buchacz, A.

2017-08-01

This work presents non-classical method of design of mechanic systems with subsystem reducing vibrations. The purpose of this paper is also introduces synthesis of mechanic system with reducing vibrations understand as design of this type of systems. The synthesis may be applied to modify the already existing systems in order to achieve a desired result. Elements which reduce vibrations can be constructed with passive, semi-active or active components. These considerations systems have selected active items. A hallmark of active elements it is possible to change the parameters on time of these elements and their power from an external source. The implementation of active elements is very broad. These elements can be implemented through the use of components of electrical, pneumatic, hydraulic, etc. The system was consisted from mechanical and hydraulic elements. Hydraulic elements were used as subsystem reducing unwanted vibration of mechanical system. Hydraulic elements can be realized in the form of hydraulic cylinder. In the case of an active vibration reduction in the form of hydraulic cylinder it is very important to find the corresponding values of hydraulic components. The values of these elements affect the frequency of vibrations of this sub-system which is related to the effective vibration reduction [7,11].

Development of a 3D parallel mechanism robot arm with three vertical-axial pneumatic actuators combined with a stereo vision system.

PubMed

Chiang, Mao-Hsiung; Lin, Hao-Ting

2011-01-01

This study aimed to develop a novel 3D parallel mechanism robot driven by three vertical-axial pneumatic actuators with a stereo vision system for path tracking control. The mechanical system and the control system are the primary novel parts for developing a 3D parallel mechanism robot. In the mechanical system, a 3D parallel mechanism robot contains three serial chains, a fixed base, a movable platform and a pneumatic servo system. The parallel mechanism are designed and analyzed first for realizing a 3D motion in the X-Y-Z coordinate system of the robot's end-effector. The inverse kinematics and the forward kinematics of the parallel mechanism robot are investigated by using the Denavit-Hartenberg notation (D-H notation) coordinate system. The pneumatic actuators in the three vertical motion axes are modeled. In the control system, the Fourier series-based adaptive sliding-mode controller with H(∞) tracking performance is used to design the path tracking controllers of the three vertical servo pneumatic actuators for realizing 3D path tracking control of the end-effector. Three optical linear scales are used to measure the position of the three pneumatic actuators. The 3D position of the end-effector is then calculated from the measuring position of the three pneumatic actuators by means of the kinematics. However, the calculated 3D position of the end-effector cannot consider the manufacturing and assembly tolerance of the joints and the parallel mechanism so that errors between the actual position and the calculated 3D position of the end-effector exist. In order to improve this situation, sensor collaboration is developed in this paper. A stereo vision system is used to collaborate with the three position sensors of the pneumatic actuators. The stereo vision system combining two CCD serves to measure the actual 3D position of the end-effector and calibrate the error between the actual and the calculated 3D position of the end-effector. Furthermore, to verify the feasibility of the proposed parallel mechanism robot driven by three vertical pneumatic servo actuators, a full-scale test rig of the proposed parallel mechanism pneumatic robot is set up. Thus, simulations and experiments for different complex 3D motion profiles of the robot end-effector can be successfully achieved. The desired, the actual and the calculated 3D position of the end-effector can be compared in the complex 3D motion control.

Development of a 3D Parallel Mechanism Robot Arm with Three Vertical-Axial Pneumatic Actuators Combined with a Stereo Vision System

PubMed Central

Chiang, Mao-Hsiung; Lin, Hao-Ting

2011-01-01

This study aimed to develop a novel 3D parallel mechanism robot driven by three vertical-axial pneumatic actuators with a stereo vision system for path tracking control. The mechanical system and the control system are the primary novel parts for developing a 3D parallel mechanism robot. In the mechanical system, a 3D parallel mechanism robot contains three serial chains, a fixed base, a movable platform and a pneumatic servo system. The parallel mechanism are designed and analyzed first for realizing a 3D motion in the X-Y-Z coordinate system of the robot’s end-effector. The inverse kinematics and the forward kinematics of the parallel mechanism robot are investigated by using the Denavit-Hartenberg notation (D-H notation) coordinate system. The pneumatic actuators in the three vertical motion axes are modeled. In the control system, the Fourier series-based adaptive sliding-mode controller with H∞ tracking performance is used to design the path tracking controllers of the three vertical servo pneumatic actuators for realizing 3D path tracking control of the end-effector. Three optical linear scales are used to measure the position of the three pneumatic actuators. The 3D position of the end-effector is then calculated from the measuring position of the three pneumatic actuators by means of the kinematics. However, the calculated 3D position of the end-effector cannot consider the manufacturing and assembly tolerance of the joints and the parallel mechanism so that errors between the actual position and the calculated 3D position of the end-effector exist. In order to improve this situation, sensor collaboration is developed in this paper. A stereo vision system is used to collaborate with the three position sensors of the pneumatic actuators. The stereo vision system combining two CCD serves to measure the actual 3D position of the end-effector and calibrate the error between the actual and the calculated 3D position of the end-effector. Furthermore, to verify the feasibility of the proposed parallel mechanism robot driven by three vertical pneumatic servo actuators, a full-scale test rig of the proposed parallel mechanism pneumatic robot is set up. Thus, simulations and experiments for different complex 3D motion profiles of the robot end-effector can be successfully achieved. The desired, the actual and the calculated 3D position of the end-effector can be compared in the complex 3D motion control. PMID:22247676

Holostrain system: a powerful tool for experimental mechanics

NASA Astrophysics Data System (ADS)

Sciammarella, Cesar A.; Bhat, Gopalakrishna K.

1992-09-01

A portable holographic interferometer that can be used to measure displacements and strains in all kinds of mechanical components and structures is described. The holostrain system captures images on a TV camera that detects interference patterns produced by laser illumination. The video signals are digitized. The digitized interferograms are processed by a fast processing system. The output of the system are the strains or the stresses of the observed mechanical component or structure.

Focal Plane Array Shutter Mechanism of the JWST NIRSpec Detector System

NASA Technical Reports Server (NTRS)

Hale, Kathleen; Sharma, Rajeev

2006-01-01

This viewgraph presentation reviews the requirements, chamber location, shutter system design, stepper motor specifications, dry lubrication, control system, the environmental cryogenic function testing and the test results of the Focal Plane Array Shutter mechanism for the James Webb Space Telescope Near Infrared Spectrum Detector system. Included are design views of the location for the Shutter Mechanism, lubricant (lubricated with Molybdenum Di Sulfide) thickness, and information gained from the cryogenic testing.

Subscription merging in filter-based publish/subscribe systems

NASA Astrophysics Data System (ADS)

Zhang, Shengdong; Shen, Rui

2013-03-01

Filter-based publish/subscribe systems suffer from high subscription maintenance cost for each broker in the system stores a large number of subscriptions. Advertisement and covering are not sufficient to conquer such problem. Thus, subscription merging is proposed. However, current researches lack of an efficient and practical merging mechanism. In this paper, we propose a novel subscription merging mechanism. The mechanism is both time and space efficient, and can flexibly control the merging granularity. The merging mechanism has been verified through both theoretical and simulation-based evaluation.

Outcomes management of mechanically ventilated patients: utilizing informatics technology.

PubMed

Smith, K R

1998-11-01

This article examines an informatics system developed for outcomes management of the mechanically ventilated adult population, focusing on weaning the patient from mechanical ventilation. The link between medical informatics and outcomes management is discussed, along with the development of methods, tools, and data sets for outcomes management of the mechanically ventilated adult population at an acute care academic institution. Pros and cons of this system are identified, and specific areas for improvement of future health care outcomes medical informatics systems are discussed.

Relatchable launch restraint mechanism for deployable booms

NASA Technical Reports Server (NTRS)

Warden, Robert M.

1990-01-01

A new Relatchable Launch Mechanism was developed which enables a deployable system to be restrained and released repeatedly rather than the normal one shot release systems of the past. The deployable systems are of the self extending type which rely on a lanyard attached to a drive motor to control the deployment and retraction. The Relatch Mechanism uses the existing drive motor to also actuate the latch. The design and kinematics of the Relatch Mechanism as used on two flight programs are described.

Structural Bus and Release Mechanisms on the ST5 Satellites: Summary and Status

NASA Technical Reports Server (NTRS)

Rossoni, Peter

2007-01-01

The Space Technology 5 Mechanical System met the challenge of packaging a fully functional science and technology satellite system with its Deployer mechanism into a compact 0.07cu m volume. Three 25 kg satellites were orbited in constellation in March, 2006. The ST5 mechanical system is composed of 1) The Structural Bus; 2) Magnetometer Instrument Boom 3) Spacecraft Deployer Release Mechanism This system includes a highly integrated electronics enclosure as a multifunctional structure; a lightweight, magnetically clean Magnetometer Boom; the first use of Nitinol Shape-Memory Alloy trigger devices for deploying multiple spacecraft; an innovative compliant mount for the umbilical connector and a Deployer mechanism that imparts both separation velocity and mission spin rate to three constellation flying satellites These elements employed cutting-edge design and analysis tools, state-of-the-art testing facilities and proven engineering techniques to meet stringent performance criteria, enabling the mission s success.

Generating giant and tunable nonlinearity in a macroscopic mechanical resonator from a single chemical bond

NASA Astrophysics Data System (ADS)

Huang, Pu; Zhou, Jingwei; Zhang, Liang; Hou, Dong; Lin, Shaochun; Deng, Wen; Meng, Chao; Duan, Changkui; Ju, Chenyong; Zheng, Xiao; Xue, Fei; Du, Jiangfeng

2016-05-01

Nonlinearity in macroscopic mechanical systems may lead to abundant phenomena for fundamental studies and potential applications. However, it is difficult to generate nonlinearity due to the fact that macroscopic mechanical systems follow Hooke's law and respond linearly to external force, unless strong drive is used. Here we propose and experimentally realize high cubic nonlinear response in a macroscopic mechanical system by exploring the anharmonicity in chemical bonding interactions. We demonstrate the high tunability of nonlinear response by precisely controlling the chemical bonding interaction, and realize, at the single-bond limit, a cubic elastic constant of 1 × 1020 N m-3. This enables us to observe the resonator's vibrational bi-states transitions driven by the weak Brownian thermal noise at 6 K. This method can be flexibly applied to a variety of mechanical systems to improve nonlinear responses, and can be used, with further improvements, to explore macroscopic quantum mechanics.

Motorcycle Repair.

ERIC Educational Resources Information Center

Hein, Jim; Bundy, Mike

This motorcycle repair curriculum guide contains the following ten areas of study: brake systems, clutches, constant mesh transmissions, final drives, suspension, mechanical starting mechanisms, electrical systems, fuel systems, lubrication systems, and overhead camshafts. Each area consists of one or more units of instruction. Each instructional…

Multiple Coaxial Catheter System for Reliable Access in Interventional Stroke Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kulcsar, Zsolt, E-mail: kulcsarzsolt22@gmail.com; Yilmaz, Hasan; Bonvin, Christophe

2010-12-15

In some patients with acute cerebral vessel occlusion, navigating mechanical thrombectomy systems is difficult due to tortuous anatomy of the aortic arch, carotid arteries, or vertebral arteries. Our purpose was to describe a multiple coaxial catheter system used for mechanical revascularization that helps navigation and manipulations in tortuous vessels. A triple or quadruple coaxial catheter system was built in 28 consecutive cases presenting with acute ischemic stroke. All cases were treated by mechanical thrombectomy with the Penumbra System. In cases of unsuccessful thrombo-aspiration, additional thrombolysis or angioplasty with stent placement was used for improving recanalization. The catheter system consisted ofmore » an outermost 8-Fr and an intermediate 6-Fr guiding catheter, containing the inner Penumbra reperfusion catheters. The largest, 4.1-Fr, reperfusion catheter was navigated over a Prowler Select Plus microcatheter. The catheter system provided access to reach the cerebral lesions and provided stability for the mechanically demanding manipulations of thromboaspiration and stent navigation in all cases. Apart from their mechanical role, the specific parts of the system could also provide access to different types of interventions, like carotid stenting through the 8-Fr guiding catheter and intracranial stenting and thrombolysis through the Prowler Select Plus microcatheter. In this series, there were no complications related to the catheter system. In conclusion, building up a triple or quadruple coaxial system proved to be safe and efficient in our experience for the mechanical thrombectomy treatment of acute ischemic stroke.« less

Overhead Crane Computer Model

NASA Astrophysics Data System (ADS)

Enin, S. S.; Omelchenko, E. Y.; Fomin, N. V.; Beliy, A. V.

2018-03-01

The paper has a description of a computer model of an overhead crane system. The designed overhead crane system consists of hoisting, trolley and crane mechanisms as well as a payload two-axis system. With the help of the differential equation of specified mechanisms movement derived through Lagrange equation of the II kind, it is possible to build an overhead crane computer model. The computer model was obtained using Matlab software. Transients of coordinate, linear speed and motor torque of trolley and crane mechanism systems were simulated. In addition, transients of payload swaying were obtained with respect to the vertical axis. A trajectory of the trolley mechanism with simultaneous operation with the crane mechanism is represented in the paper as well as a two-axis trajectory of payload. The designed computer model of an overhead crane is a great means for studying positioning control and anti-sway control systems.

Cavity opto-mechanics using an optically levitated nanosphere

PubMed Central

Chang, D. E.; Regal, C. A.; Papp, S. B.; Wilson, D. J.; Ye, J.; Painter, O.; Kimble, H. J.; Zoller, P.

2010-01-01

Recently, remarkable advances have been made in coupling a number of high-Q modes of nano-mechanical systems to high-finesse optical cavities, with the goal of reaching regimes in which quantum behavior can be observed and leveraged toward new applications. To reach this regime, the coupling between these systems and their thermal environments must be minimized. Here we propose a novel approach to this problem, in which optically levitating a nano-mechanical system can greatly reduce its thermal contact, while simultaneously eliminating dissipation arising from clamping. Through the long coherence times allowed, this approach potentially opens the door to ground-state cooling and coherent manipulation of a single mesoscopic mechanical system or entanglement generation between spatially separate systems, even in room-temperature environments. As an example, we show that these goals should be achievable when the mechanical mode consists of the center-of-mass motion of a levitated nanosphere. PMID:20080573

Equation Discovery for Model Identification in Respiratory Mechanics of the Mechanically Ventilated Human Lung

NASA Astrophysics Data System (ADS)

Ganzert, Steven; Guttmann, Josef; Steinmann, Daniel; Kramer, Stefan

Lung protective ventilation strategies reduce the risk of ventilator associated lung injury. To develop such strategies, knowledge about mechanical properties of the mechanically ventilated human lung is essential. This study was designed to develop an equation discovery system to identify mathematical models of the respiratory system in time-series data obtained from mechanically ventilated patients. Two techniques were combined: (i) the usage of declarative bias to reduce search space complexity and inherently providing the processing of background knowledge. (ii) A newly developed heuristic for traversing the hypothesis space with a greedy, randomized strategy analogical to the GSAT algorithm. In 96.8% of all runs the applied equation discovery system was capable to detect the well-established equation of motion model of the respiratory system in the provided data. We see the potential of this semi-automatic approach to detect more complex mathematical descriptions of the respiratory system from respiratory data.

Aromatherapy and the central nerve system (CNS): therapeutic mechanism and its associated genes.

PubMed

Lv, Xiao Nan; Liu, Zhu Jun; Zhang, Huan Jing; Tzeng, Chi Meng

2013-07-01

Molecular medical research on aromatherapy has been steadily increasing for use as an adjuvant therapy in managing psychiatric disorders and to examine its therapeutic mechanisms. Most studies, as well as clinically applied experience, have indicated that various essential oils, such as lavender, lemon and bergamot can help to relieve stress, anxiety, depression and other mood disorders. Most notably, inhalation of essential oils can communicate signals to the olfactory system and stimulate the brain to exert neurotransmitters (e.g. serotonin and dopamine) thereby further regulating mood. However, little research has been done on the molecular mechanisms underlying these effects, thus their mechanism of action remains ambiguous. Several hypotheses have been proposed regarding the therapeutic mechanism of depression. These have mainly centered on possible deficiencies in monoamines, neurotrophins, the neuroendocrine system, c-AMP, cation channels as well as neuroimmune interactions and epigenetics, however the precise mechanism or mechanisms related to depression have yet to be elucidated. In the current study, the effectiveness of aromatherapy for alleviating psychiatric disorders was examined using data collected from previously published studies and our unpublished data. A possible signaling pathway from olfactory system to the central nerve system and the associated key molecular elements of aromatherapy are also proposed.

Decentralized Modular Systems Versus Centralized Systems.

ERIC Educational Resources Information Center

Crossey, R. E.

Building design, planning, and construction programing for modular decentralized mechanical building systems are outlined in terms of costs, performance, expansion and flexibility. Design strategy, approach, and guidelines for implementing such systems for buildings are suggested, with emphasis on mechanical equipment and building element…

Biofluid mechanics of special organs and the issue of system control. Sixth International Bio-Fluid Mechanics Symposium and Workshop, March 28-30, 2008 Pasadena, California.

PubMed

Zamir, Mair; Moore, James E; Fujioka, Hideki; Gaver, Donald P

2010-03-01

In the field of fluid flow within the human body, focus has been placed on the transportation of blood in the systemic circulation since the discovery of that system; but, other fluids and fluid flow phenomena pervade the body. Some of the most fascinating fluid flow phenomena within the human body involve fluids other than blood and a service other than transport--the lymphatic and pulmonary systems are two striking examples. While transport is still involved in both cases, this is not the only service which they provide and blood is not the only fluid involved. In both systems, filtration, extraction, enrichment, and in general some "treatment" of the fluid itself is the primary function. The study of the systemic circulation has also been conventionally limited to treating the system as if it were an open-loop system governed by the laws of fluid mechanics alone, independent of physiological controls and regulations. This implies that system failures can be explained fully in terms of the laws of fluid mechanics, which of course is not the case. In this paper we examine the clinical implications of these issues and of the special biofluid mechanics issues involved in the lymphatic and pulmonary systems.

Characterising the development of the understanding of human body systems in high-school biology students - a longitudinal study

NASA Astrophysics Data System (ADS)

Snapir, Zohar; Eberbach, Catherine; Ben-Zvi-Assaraf, Orit; Hmelo-Silver, Cindy; Tripto, Jaklin

2017-10-01

Science education today has become increasingly focused on research into complex natural, social and technological systems. In this study, we examined the development of high-school biology students' systems understanding of the human body, in a three-year longitudinal study. The development of the students' system understanding was evaluated using the Components Mechanisms Phenomena (CMP) framework for conceptual representation. We coded and analysed the repertory grid personal constructs of 67 high-school biology students at 4 points throughout the study. Our data analysis builds on the assumption that systems understanding entails a perception of all the system categories, including structures within the system (its Components), specific processes and interactions at the macro and micro levels (Mechanisms), and the Phenomena that present the macro scale of processes and patterns within a system. Our findings suggest that as the learning process progressed, the systems understanding of our students became more advanced, moving forward within each of the major CMP categories. Moreover, there was an increase in the mechanism complexity presented by the students, manifested by more students describing mechanisms at the molecular level. Thus, the 'mechanism' category and the micro level are critical components that enable students to understand system-level phenomena such as homeostasis.

Infusion of Emerging Technologies and New Teaching Methods into the Mechanical Engineering Curriculum at the City College of New York

ERIC Educational Resources Information Center

Delale, Feridun; Liaw, Benjamin M.; Jiji, Latif M.; Voiculescu, Ioana; Yu, Honghui

2011-01-01

From October 2003 to April 2008 a systemic reform of the Mechanical Engineering program at The City College of New York was undertaken with the goal of incorporating emerging technologies (such as nanotechnology, biotechnology, Micro-Electro-Mechanical Systems (MEMS), intelligent systems) and new teaching methodologies (such as project based…

The dynamical behaviour of our planetary system. Proceedings. 4th Alexander von Humboldt Colloquium on Celestial Mechanics, Ramsau (Austria), 17 - 23 Mar 1996.

NASA Astrophysics Data System (ADS)

Dvorak, R.; Henrard, J.

1996-03-01

The following topics were dealt with: celestial mechanics, dynamical astronomy, planetary systems, resonance scattering, Hamiltonian mechanics non-integrability, irregular periodic orbits, escape, dynamical system mapping, fast Fourier method, precession-nutation, Nekhoroshev theorem, asteroid dynamics, the Trojan problem, planet-crossing orbits, Kirkwood gaps, future research, human comprehension limitations.

White House Communications Agency (WHCA) Presidential Voice Communications Rack Mount System Mechanical Drawing Package

DTIC Science & Technology

2015-12-01

Rack Mount System Mechanical Drawing Package by Steven P Callaway Approved for public release; distribution unlimited...Laboratory White House Communications Agency (WHCA) Presidential Voice Communications Rack Mount System Mechanical Drawing Package by Steven P...Note 3. DATES COVERED (From - To) 04/2013 4. TITLE AND SUBTITLE White House Communications Agency (WHCA) Presidential Voice Communications Rack

The orbiter mate/demate device

NASA Technical Reports Server (NTRS)

Miller, A. J.; Binkley, W. H.

1985-01-01

The numerous components and systems of the space shuttle orbiter mate/demate device (MDD) are discussed. Special emphasis is given, mechanisms and mechanical systems to discuss in general their requirements, functions, and design; and, where applicable, to relate any unusual problems encountered during the initial concept studies, final design, and construction are discussed. The MDD and its electrical, machinery, and mechanical systems, including the main hoisting system, power operated access service platform, wind restrain and adjustment mechanism, etc., were successfully designed and constructed. The MDD was used routinely during the initial orbiter-747 approach and landing test and the more recent orbiter flight tests recovery and mate operations.

A piezoelectric transformer

NASA Technical Reports Server (NTRS)

Won, C. C.

1993-01-01

This work describes a modeling and design method whereby a piezoelectric system is formulated by two sets of second-order equations, one for the mechanical system, and the other for the electrical system, coupled through the piezoelectric effect. The solution to this electromechanical coupled system gives a physical interpretation of the piezoelectric effect as a piezoelectric transformer that is a part of the piezoelectric system, which transfers the applied mechanical force into a force-controlled current source, and short circuit mechanical compliance into capacitance. It also transfers the voltage source into a voltage-controlled relative velocity input, and free motional capacitance into mechanical compliance. The formulation and interpretation simplify the modeling of smart structures and lead to physical insight that aids the designer. Due to its physical realization, the smart structural system can be unconditional stable and effectively control responses. This new concept has been demonstrated in three numerical examples for a simple piezoelectric system.

Active noise canceling system for mechanically cooled germanium radiation detectors

DOEpatents

Nelson, Karl Einar; Burks, Morgan T

2014-04-22

A microphonics noise cancellation system and method for improving the energy resolution for mechanically cooled high-purity Germanium (HPGe) detector systems. A classical adaptive noise canceling digital processing system using an adaptive predictor is used in an MCA to attenuate the microphonics noise source making the system more deployable.

Study on the position accuracy of a mechanical alignment system

NASA Astrophysics Data System (ADS)

Cai, Yimin

In this thesis, we investigated the precision level and established the baseline achieved by a mechanical alignment system using datums and reference surfaces. The factors which affect the accuracy of mechanical alignment system were studied and methodology was developed to suppress these factors so as to reach its full potential precision. In order to characterize the mechanical alignment system quantitatively, a new optical position monitoring system by using quadrant detectors has been developed in this thesis, it can monitor multi-dimensional degrees of mechanical workpieces in real time with high precision. We studied the noise factors inside the system and optimized the optical system. Based on the fact that one of the major limiting noise factors is the shifting of the laser beam, a noise cancellation technique has been developed successfully to suppress this noise, the feasibility of an ultra high resolution (<20 A) for displacement monitoring has been demonstrated. Using the optical position monitoring system, repeatability experiment of the mechanical alignment system has been conducted on different kinds of samples including steel, aluminum, glass and plastics with the same size 100mm x 130mm. The alignment accuracy was studied quantitatively rather than qualitatively before. In a controlled environment, the alignment precision can be improved 5 folds by securing the datum without other means of help. The alignment accuracy of an aluminum workpiece having reference surface by milling is about 3 times better than by shearing. Also we have found that sample material can have fairly significant effect on the alignment precision of the system. Contamination trapped between the datum and reference surfaces in mechanical alignment system can cause errors of registration or reduce the level of manufacturing precision. In the thesis, artificial and natural dust particles were used to simulate the real situations and their effects on system precision have been investigated. In this experiment, we discovered two effective cleaning processes.

Single-source mechanical loading system produces biaxial stresses in cylinders

NASA Technical Reports Server (NTRS)

Flower, J. F.; Stafford, R. L.

1967-01-01

Single-source mechanical loading system proportions axial-to-hoop tension loads applied to cylindrical specimens. The system consists of hydraulic, pneumatic, and lever arrangements which produce biaxial loading ratios.

Effect of chemical and mechanical weed control on cassava yield, soil quality and erosion under cassava cropping system

NASA Astrophysics Data System (ADS)

Islami, Titiek; Wisnubroto, Erwin; Utomo, Wani

2016-04-01

Three years field experiments were conducted to study the effect of chemical and mechanical weed control on soil quality and erosion under cassava cropping system. The experiment were conducted at University Brawijaya field experimental station, Jatikerto, Malang, Indonesia. The experiments were carried out from 2011 - 2014. The treatments consist of three cropping system (cassava mono culture; cassava + maize intercropping and cassava + peanut intercropping), and two weed control method (chemical and mechanical methods). The experimental result showed that the yield of cassava first year and second year did not influenced by weed control method and cropping system. However, the third year yield of cassava was influence by weed control method and cropping system. The cassava yield planted in cassava + maize intercropping system with chemical weed control methods was only 24 t/ha, which lower compared to other treatments, even with that of the same cropping system used mechanical weed control. The highest cassava yield in third year was obtained by cassava + peanuts cropping system with mechanical weed control method. After three years experiment, the soil of cassava monoculture system with chemical weed control method possessed the lowest soil organic matter, and soil aggregate stability. During three years of cropping soil erosion in chemical weed control method, especially on cassava monoculture, was higher compared to mechanical weed control method. The soil loss from chemical control method were 40 t/ha, 44 t/ha and 54 t/ha for the first, second and third year crop. The soil loss from mechanical weed control method for the same years was: 36 t/ha, 36 t/ha and 38 t/ha. Key words: herbicide, intercropping, soil organic matter, aggregate stability.

A model of mechanical interactions between heart and lungs.

PubMed

Fontecave Jallon, Julie; Abdulhay, Enas; Calabrese, Pascale; Baconnier, Pierre; Gumery, Pierre-Yves

2009-12-13

To study the mechanical interactions between heart, lungs and thorax, we propose a mathematical model combining a ventilatory neuromuscular model and a model of the cardiovascular system, as described by Smith et al. (Smith, Chase, Nokes, Shaw & Wake 2004 Med. Eng. Phys.26, 131-139. (doi:10.1016/j.medengphy.2003.10.001)). The respiratory model has been adapted from Thibault et al. (Thibault, Heyer, Benchetrit & Baconnier 2002 Acta Biotheor. 50, 269-279. (doi:10.1023/A:1022616701863)); using a Liénard oscillator, it allows the activity of the respiratory centres, the respiratory muscles and rib cage internal mechanics to be simulated. The minimal haemodynamic system model of Smith includes the heart, as well as the pulmonary and systemic circulation systems. These two modules interact mechanically by means of the pleural pressure, calculated in the mechanical respiratory system, and the intrathoracic blood volume, calculated in the cardiovascular model. The simulation by the proposed model provides results, first, close to experimental data, second, in agreement with the literature results and, finally, highlighting the presence of mechanical cardiorespiratory interactions.

Mechanical model for simulating the conditioning of air in the respiratory tract.

PubMed

Bergonse Neto, Nelson; Von Bahten, Luiz Carlos; Moura, Luís Mauro; Coelho, Marlos de Souza; Stori Junior, Wilson de Souza; Bergonse, Gilberto da Fontoura Rey

2007-01-01

To create a mechanical model that could be regulated to simulate the conditioning of inspired and expired air with the same normal values of temperature, pressure, and relative humidity as those of the respiratory system of a healthy young man on mechanical ventilation. Using several types of materials, a mechanical device was built and regulated using normal values of vital capacity, tidal volume, maximal inspiratory pressure, positive end-expiratory pressure, and gas temperature in the system. The device was submitted to mechanical ventilation for a period of 29.8 min. The changes in the temperature of the air circulating in the system were recorded every two seconds. The statistical analysis of the data collected revealed that the device was approximately as efficient in the conditioning of air as is the respiratory system of a human being. By the study endpoint, we had developed a mechanical device capable of simulating the conditioning of air in the respiratory tract. The device mimics the conditions of temperature, pressure, and relative humidity seen in the respiratory system of healthy individuals.

Soft bio-integrated systems for continuous health monitoring

NASA Astrophysics Data System (ADS)

Raj, M.; Wei, P. H.; Morey, B.; Wang, X.; Keen, B.; DePetrillo, P.; Hsu, Y. Y.; Ghaffari, R.

2014-06-01

Electronically-enabled wearable systems that monitor physiological activity and electrophysiological activity hold the key to truly personalized medical care outside of the hospital setting. However, fundamental technical challenges exist in achieving medical systems that are comfortable, unobtrusive and fully integrated without external connections to bench top instruments. In particular, there is a fundamental mismatch in mechanical coupling between existing classes of rigid electronics and soft biological substrates, like the skin. Here we describe new mechanical and electrical design strategies for wearable devices with mechanical properties that approach that of biological tissue. These systems exploit stretchable networks of conformal sensors (i.e. electrodes, temperature sensors, and accelerometers) and associated circuitry (i.e. microcontroller, memory, voltage regulators, rechargeable battery, wireless communication modules) embedded in ultrathin, elastomeric substrates. Quantitative analyses of sensor performance and mechanics under tensile and torsional stresses illustrate the ability to mechanically couple with soft tissues in a way that is mechanically invisible to the user. Representative examples of these soft biointegrated systems can be applied for continuous sensing of muscle and movement activity in the home and ambulatory settings.

Man-vehicle systems research facility advanced aircraft flight simulator throttle mechanism

NASA Technical Reports Server (NTRS)

Kurasaki, S. S.; Vallotton, W. C.

1985-01-01

The Advanced Aircraft Flight Simulator is equipped with a motorized mechanism that simulates a two engine throttle control system that can be operated via a computer driven performance management system or manually by the pilots. The throttle control system incorporates features to simulate normal engine operations and thrust reverse and vary the force feel to meet a variety of research needs. While additional testing to integrate the work required is principally now in software design, since the mechanical aspects function correctly. The mechanism is an important part of the flight control system and provides the capability to conduct human factors research of flight crews with advanced aircraft systems under various flight conditions such as go arounds, coupled instrument flight rule approaches, normal and ground operations and emergencies that would or would not normally be experienced in actual flight.

Kinematics Analysis of End Effector for Carrier Robot of Feeding Broiler Chicken System

NASA Astrophysics Data System (ADS)

Syam, Rafiuddin; Arsyad, Hairul; Bauna, Ruslan; Renreng, Ilyas; Bakhri, Syaiful

2018-02-01

The demand for commodities, especially Broiler chicken farms are increasing, the volume of feed requirements Broiler chickens increased with age up to the age of 30-57 days required feed 3,829 grams/day/head, so if the chicken population is 3,000 needed transporting feed 11 487 kg/day, This research aims to produce a robot capable of transporting feed in the top of the cage by using a control system so as to make efficient use of manpower. Design robot performed using software design three-dimensional Solidworks2010, process of making the robot is started with the design manufacture three (3) units of mechanical systems (mechanical system for holder feed, mechanical systems for lifter feed and mechanical systems for transporting feed), then do the design process framework as a component buffer so that the mechanical system will work properly and safely when the robot operates. Furthermore, the manufacture of electronic circuits and control are using Arduino Mega microcontroller. After assembling all components mechanical systems and installation of electronic systems and control, then experiments to evaluate the performance of the robot have been made. The results of experiments showed that all components work well according to plan, in particular the speed and acceleration of end effector motion so it can hold and release the feed well. This strongly supports the robots perform tasks in accordance with the intent, i.e., holding, lifting and moving feed.

High Gain Antenna System Deployment Mechanism Integration, Characterization, and Lessons Learned

NASA Technical Reports Server (NTRS)

Parong, Fil; Russell, Blair; Garcen, Walter; Rose, Chris; Johnson, Chris; Huber, Craig

2014-01-01

The integration and deployment testing of the High Gain Antenna System (HGAS) for the Global Precipitation Measurement mission is summarized. The HGAS deployment mechanism is described. The gravity negation system configuration and its influence on vertical, ground-based deployment tests are presented with test data and model predictions. A focus is made on the late discovery and resolution of a potentially mission-degrading deployment interference condition. The interaction of the flight deployment mechanism, gravity-negation mechanism, and use of dynamic modeling is described and lessons learned presented

High Gain Antenna System Deployment Mechanism Integration, Characterization, and Lessons Learned

NASA Technical Reports Server (NTRS)

Parong, Fil; Russell, Blair; Garcen, Walter; Rose, Chris; Johnson, Chris; Huber, Craig

2014-01-01

The integration and deployment testing of the High Gain Antenna System for the Global Precipitation Measurement mission is summarized. The HGAS deployment mechanism is described. The gravity negation system configuration and its influence on vertical, ground-based, deployment tests are presented with test data and model predictions. A focus is made on the late discovery and resolution of a potentially mission degrading deployment interference condition. The interaction of the flight deployment mechanism, gravity negation mechanism, and use of dynamic modeling is described and lessons learned presented.

A Taxonomy of Coordination Mechanisms Used in Real-Time Software Based on Domain Analysis

DTIC Science & Technology

1993-12-01

real - time operating system . CMU/SEI-93-TR-34 3 1.3 Related Work Several taxonomies...coordination methods supported by a real - time operating system is presented by Ripps. The classification of the coordination methods rests upon a set...mechanisms avail- able today. The classification proposed by Ripps [Ripps 89] includes the mechanisms supported by a real - time operating system .

Evaluation of Mechanical Ventilator Use with Liquid Oxygen Systems

DTIC Science & Technology

2017-02-22

patients using long-term liquid oxygen differ from those on traditional treatment with oxygen concentrators and/or compressed gas cylinders? A...AFRL-SA-WP-SR-2017-0006 Evaluation of Mechanical Ventilator Use with Liquid Oxygen Systems Thomas Blakeman, MSc, RRT; Dario...To) August 2014 – September 2016 4. TITLE AND SUBTITLE Evaluation of Mechanical Ventilator Use with Liquid Oxygen Systems 5a. CONTRACT NUMBER

Research on the energy and ecological efficiency of mechanical equipment remanufacturing systems

NASA Astrophysics Data System (ADS)

Shi, Junli; Cheng, Jinshi; Ma, Qinyi; Wang, Yajun

2017-08-01

According to the characteristics of mechanical equipment remanufacturing system, the dynamic performance of energy consumption and emission is explored, the equipment energy efficiency and emission analysis model is established firstly, and then energy and ecological efficiency analysis method of the remanufacturing system is put forward, at last, the energy and ecological efficiency of WD615.87 automotive diesel engine remanufacturing system as an example is analyzed, the way of energy efficiency improvementnt and environmental friendly mechanism of remanufacturing process is put forward.

Supernovae in Binary Systems: An Application of Classical Mechanics.

ERIC Educational Resources Information Center

Mitalas, R.

1980-01-01

Presents the supernova explosion in a binary system as an application of classical mechanics. This presentation is intended to illustrate the power of the equivalent one-body problem and provide undergraduate students with a variety of insights into elementary classical mechanics. (HM)

[Vascular dental anaesthesias and their mechanism].

PubMed

Petrikas, A Zh; Iakupova, L A; Medvedev, A V; Borodina, O E; Egorova, V A; Diuba

2010-01-01

By their mechanism of action local anaesthesia methods were divided into diffused and vascular. Intraosseous, intraseptal and intraligamental anesthaesias are vascular ones at capillary-venous system level. Circulatory mechanism besides effectiveness increased more than 2-fold and also promotes enhancement of cardiovascular system responses.

Methods for multi-material stereolithography

DOEpatents

Wicker, Ryan [El Paso, TX; Medina, Francisco [El Paso, TX; Elkins, Christopher [Redwood City, CA

2011-06-14

Methods and systems of stereolithography for building cost-efficient and time-saving multi-material, multi-functional and multi-colored prototypes, models and devices configured for intermediate washing and curing/drying is disclosed including: laser(s), liquid and/or platform level sensing system(s), controllable optical system(s), moveable platform(s), elevator platform(s), recoating system(s) and at least one polymer retaining receptacle. Multiple polymer retaining receptacles may be arranged in a moveable apparatus, wherein each receptacle is adapted to actively/passively maintain a uniform, desired level of polymer by including a recoating device and a material fill/remove system. The platform is movably accessible to the polymer retaining receptacle(s), elevator mechanism(s) and washing and curing/drying area(s) which may be housed in a shielded enclosure(s). The elevator mechanism is configured to vertically traverse and rotate the platform, thus providing angled building, washing and curing/drying capabilities. A horizontal traversing mechanism may be included to facilitate manufacturing between components of SL cabinet(s) and/or alternative manufacturing technologies.

A vibroacoustic diagnostic system as an element improving road transport safety.

PubMed

Komorska, Iwona

2013-01-01

Mechanical defects of a vehicle driving system can be dangerous on the road. Diagnostic systems, which monitor operations of electric and electronic elements and devices of vehicles, are continuously developed and improved, while defects of mechanical systems are still not managed properly. This article proposes supplementing existing on-board diagnostics with a system of diagnosing selected defects to minimize their impact. It presents a method of diagnosing mechanical defects of the engine, gearbox and other elements of the driving system on the basis of a model of the vibration signal obtained adaptively. This method is suitable for engine valves, engine head gasket, main gearbox, joints, etc.

The Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX) yo-yo despin and solar array deployment mechanism

NASA Technical Reports Server (NTRS)

Kellogg, James W.

1993-01-01

The SAMPEX spacecraft, successfully launched in July 1992, carried a yo-yo despin system and deployable solar arrays. The despin and solar array mechanisms formed an integral system as the yo-yo cables held the solar array release mechanism in place. The SAMPEX design philosophy was to minimize size and weight through the use of a predominantly single string system. The design challenge was to build a system in a limited space, which was reliable with minimal redundancy. This paper covers the design and development of the SAMPEX yo-yo despin and solar array deployment mechanisms. The problems encountered during development and testing will also be discussed.

Qubit Coupled Mechanical Resonator in an Electromechanical System

NASA Astrophysics Data System (ADS)

Hao, Yu

This thesis describes the development of a hybrid quantum electromechanical system. In this system the mechanical resonator is capacitively coupled to a superconducting transmon which is embedded in a superconducting coplanar waveguide (CPW) cavity. The difficulty of achieving high quality of superconducting qubit in a high-quality voltage-biased cavity is overcome by integrating a superconducting reflective T-filter to the cavity. Further spectroscopic and pulsed measurements of the hybrid system demonstrate interactions between the ultra-high frequency mechanical resonator and transmon qubit. The noise of mechanical resonator close to ground state is measured by looking at the spectroscopy of the transmon. At last, fabrication and tests of membrane resonators are discussed.

Standardized Curriculum for Automotive Mechanics.

ERIC Educational Resources Information Center

Mississippi State Dept. of Education, Jackson. Office of Vocational, Technical and Adult Education.

Standardized curricula are provided for two courses for the secondary vocational education program in Mississippi: automotive mechanics I and II. The six units in automotive mechanics I are as follows: orientation and safety; tools, equipment, and manuals; measurement; automotive engines; basic electrical systems; and fuel systems. Automotive…

Cooperation, conflict, and the evolution of queen pheromones.

PubMed

Kocher, Sarah D; Grozinger, Christina M

2011-11-01

While chemical communication regulates individual behavior in a wide variety of species, these communication systems are most elaborated in insect societies. In these complex systems, pheromones produced by the reproductive individuals (queens) are critical in establishing and maintaining dominant reproductive status over hundreds to thousands of workers. The proximate and ultimate mechanisms by which these intricate pheromone communication systems evolved are largely unknown, though there has been much debate over whether queen pheromones function as a control mechanism or as an honest signal facilitating cooperation. Here, we summarize results from recent studies in honey bees, bumble bees, wasps, ants and termites. We further discuss evolutionary mechanisms by which queen pheromone communication systems may have evolved. Overall, these studies suggest that queen-worker pheromone communication is a multi-component, labile dialog between the castes, rather than a simple, fixed signal-response system. We also discuss future approaches that can shed light on the proximate and ultimate mechanisms that underlie these complex systems by focusing on the development of increasingly sophisticated genomic tools and their potential applications to examine the molecular mechanisms that regulate pheromone production and perception.

Many-Body Localization and Thermalization in Quantum Statistical Mechanics

NASA Astrophysics Data System (ADS)

Nandkishore, Rahul; Huse, David A.

2015-03-01

We review some recent developments in the statistical mechanics of isolated quantum systems. We provide a brief introduction to quantum thermalization, paying particular attention to the eigenstate thermalization hypothesis (ETH) and the resulting single-eigenstate statistical mechanics. We then focus on a class of systems that fail to quantum thermalize and whose eigenstates violate the ETH: These are the many-body Anderson-localized systems; their long-time properties are not captured by the conventional ensembles of quantum statistical mechanics. These systems can forever locally remember information about their local initial conditions and are thus of interest for possibilities of storing quantum information. We discuss key features of many-body localization (MBL) and review a phenomenology of the MBL phase. Single-eigenstate statistical mechanics within the MBL phase reveal dynamically stable ordered phases, and phase transitions among them, that are invisible to equilibrium statistical mechanics and can occur at high energy and low spatial dimensionality, where equilibrium ordering is forbidden.

Optomechanical transistor with mechanical gain

NASA Astrophysics Data System (ADS)

Zhang, X. Z.; Tian, Lin; Li, Yong

2018-04-01

We study an optomechanical transistor, where an input field can be transferred and amplified unidirectionally in a cyclic three-mode optomechanical system. In this system, the mechanical resonator is coupled simultaneously to two cavity modes. We show that it only requires a finite mechanical gain to achieve the nonreciprocal amplification. Here the nonreciprocity is caused by the phase difference between the linearized optomechanical couplings that breaks the time-reversal symmetry of this system. The amplification arises from the mechanical gain, which provides an effective phonon bath that pumps the mechanical mode coherently. This effect is analogous to the stimulated emission of atoms, where the probe field can be amplified when its frequency is in resonance with that of the anti-Stokes transition. We show that by choosing optimal parameters, this optomechanical transistor can reach perfect unidirectionality accompanied with strong amplification. In addition, the presence of the mechanical gain can result in ultralong delay in the phase of the probe field, which provides an alternative to controlling light transport in optomechanical systems.

Overview of Glenn Mechanical Components Branch Research

NASA Astrophysics Data System (ADS)

Zakrajsek, James

2002-09-01

Mr. James Zakrajsek, chief of the Mechanical Components Branch, gave an overview of research conducted by the branch. Branch members perform basic research on mechanical components and systems, including gears and bearings, turbine seals, structural and thermal barrier seals, and space mechanisms. The research is focused on propulsion systems for present and advanced aerospace vehicles. For rotorcraft and conventional aircraft, we conduct research to develop technology needed to enable the design of low noise, ultra safe geared drive systems. We develop and validate analytical models for gear crack propagation, gear dynamics and noise, gear diagnostics, bearing dynamics, and thermal analyses of gear systems using experimental data from various component test rigs. In seal research we develop and test advanced turbine seal concepts to increase efficiency and durability of turbine engines. We perform experimental and analytical research to develop advanced thermal barrier seals and structural seals for current and next generation space vehicles. Our space mechanisms research involves fundamental investigation of lubricants, materials, components and mechanisms for deep space and planetary environments.

Generating giant and tunable nonlinearity in a macroscopic mechanical resonator from a single chemical bond.

PubMed

Huang, Pu; Zhou, Jingwei; Zhang, Liang; Hou, Dong; Lin, Shaochun; Deng, Wen; Meng, Chao; Duan, Changkui; Ju, Chenyong; Zheng, Xiao; Xue, Fei; Du, Jiangfeng

2016-05-26

Nonlinearity in macroscopic mechanical systems may lead to abundant phenomena for fundamental studies and potential applications. However, it is difficult to generate nonlinearity due to the fact that macroscopic mechanical systems follow Hooke's law and respond linearly to external force, unless strong drive is used. Here we propose and experimentally realize high cubic nonlinear response in a macroscopic mechanical system by exploring the anharmonicity in chemical bonding interactions. We demonstrate the high tunability of nonlinear response by precisely controlling the chemical bonding interaction, and realize, at the single-bond limit, a cubic elastic constant of 1 × 10(20) N m(-3). This enables us to observe the resonator's vibrational bi-states transitions driven by the weak Brownian thermal noise at 6 K. This method can be flexibly applied to a variety of mechanical systems to improve nonlinear responses, and can be used, with further improvements, to explore macroscopic quantum mechanics.

Generating giant and tunable nonlinearity in a macroscopic mechanical resonator from a single chemical bond

PubMed Central

Huang, Pu; Zhou, Jingwei; Zhang, Liang; Hou, Dong; Lin, Shaochun; Deng, Wen; Meng, Chao; Duan, Changkui; Ju, Chenyong; Zheng, Xiao; Xue, Fei; Du, Jiangfeng

2016-01-01

Nonlinearity in macroscopic mechanical systems may lead to abundant phenomena for fundamental studies and potential applications. However, it is difficult to generate nonlinearity due to the fact that macroscopic mechanical systems follow Hooke's law and respond linearly to external force, unless strong drive is used. Here we propose and experimentally realize high cubic nonlinear response in a macroscopic mechanical system by exploring the anharmonicity in chemical bonding interactions. We demonstrate the high tunability of nonlinear response by precisely controlling the chemical bonding interaction, and realize, at the single-bond limit, a cubic elastic constant of 1 × 1020 N m−3. This enables us to observe the resonator's vibrational bi-states transitions driven by the weak Brownian thermal noise at 6 K. This method can be flexibly applied to a variety of mechanical systems to improve nonlinear responses, and can be used, with further improvements, to explore macroscopic quantum mechanics. PMID:27225287

Objects Architecture: A Comprehensive Design Approach for Real-Time, Distributed, Fault-Tolerant, Reactive Operating Systems.

DTIC Science & Technology

1987-09-01

real - time operating system should be efficient from the real-time point...5,8]) system naming scheme. 3.2 Protecting Objects Real-time embedded systems usually neglect protection mechanisms. However, a real - time operating system cannot...allocation mechanism should adhere to application constraints. This strong relationship between a real - time operating system and the application

Advanced electro-mechanical micro-shutters for thermal infrared night vision imaging and targeting systems

NASA Astrophysics Data System (ADS)

Durfee, David; Johnson, Walter; McLeod, Scott

2007-04-01

Un-cooled microbolometer sensors used in modern infrared night vision systems such as driver vehicle enhancement (DVE) or thermal weapons sights (TWS) require a mechanical shutter. Although much consideration is given to the performance requirements of the sensor, supporting electronic components and imaging optics, the shutter technology required to survive in combat is typically the last consideration in the system design. Electro-mechanical shutters used in military IR applications must be reliable in temperature extremes from a low temperature of -40°C to a high temperature of +70°C. They must be extremely light weight while having the ability to withstand the high vibration and shock forces associated with systems mounted in military combat vehicles, weapon telescopic sights, or downed unmanned aerial vehicles (UAV). Electro-mechanical shutters must have minimal power consumption and contain circuitry integrated into the shutter to manage battery power while simultaneously adapting to changes in electrical component operating parameters caused by extreme temperature variations. The technology required to produce a miniature electro-mechanical shutter capable of fitting into a rifle scope with these capabilities requires innovations in mechanical design, material science, and electronics. This paper describes a new, miniature electro-mechanical shutter technology with integrated power management electronics designed for extreme service infra-red night vision systems.

Mechanical discrete simulator of the electro-mechanical lift with n:1 roping

NASA Astrophysics Data System (ADS)

Alonso, F. J.; Herrera, I.

2016-05-01

The design process of new products in lift engineering is a difficult task due to, mainly, the complexity and slenderness of the lift system, demanding a predictive tool for the lift mechanics. A mechanical ad-hoc discrete simulator, as an alternative to ‘general purpose’ mechanical simulators is proposed. Firstly, the synthesis and experimentation process that has led to establish a suitable model capable of simulating accurately the response of the electromechanical lift is discussed. Then, the equations of motion are derived. The model comprises a discrete system of 5 vertically displaceable masses (car, counterweight, car frame, passengers/loads and lift drive), an inertial mass of the assembly tension pulley-rotor shaft which can rotate about the machine axis and 6 mechanical connectors with 1:1 suspension layout. The model is extended to any n:1 roping lift by setting 6 equivalent mechanical components (suspension systems for car and counterweight, lift drive silent blocks, tension pulley-lift drive stator and passengers/load equivalent spring-damper) by inductive inference from 1:1 and generalized 2:1 roping system. The application to simulate real elevator systems is proposed by numeric time integration of the governing equations using the Kutta-Meden algorithm and implemented in a computer program for ad-hoc elevator simulation called ElevaCAD.

Dirac structures in vakonomic mechanics

NASA Astrophysics Data System (ADS)

Jiménez, Fernando; Yoshimura, Hiroaki

2015-08-01

In this paper, we explore dynamics of the nonholonomic system called vakonomic mechanics in the context of Lagrange-Dirac dynamical systems using a Dirac structure and its associated Hamilton-Pontryagin variational principle. We first show the link between vakonomic mechanics and nonholonomic mechanics from the viewpoints of Dirac structures as well as Lagrangian submanifolds. Namely, we clarify that Lagrangian submanifold theory cannot represent nonholonomic mechanics properly, but vakonomic mechanics instead. Second, in order to represent vakonomic mechanics, we employ the space TQ ×V∗, where a vakonomic Lagrangian is defined from a given Lagrangian (possibly degenerate) subject to nonholonomic constraints. Then, we show how implicit vakonomic Euler-Lagrange equations can be formulated by the Hamilton-Pontryagin variational principle for the vakonomic Lagrangian on the extended Pontryagin bundle (TQ ⊕T∗ Q) ×V∗. Associated with this variational principle, we establish a Dirac structure on (TQ ⊕T∗ Q) ×V∗ in order to define an intrinsic vakonomic Lagrange-Dirac system. Furthermore, we also establish another construction for the vakonomic Lagrange-Dirac system using a Dirac structure on T∗ Q ×V∗, where we introduce a vakonomic Dirac differential. Finally, we illustrate our theory of vakonomic Lagrange-Dirac systems by some examples such as the vakonomic skate and the vertical rolling coin.

Robustness mechanisms in primate societies: a perturbation study

PubMed Central

Flack, Jessica C; Krakauer, David C; de Waal, Frans B. M

2005-01-01

Conflict management mechanisms have a direct, critical effect on system robustness because they mitigate conflict intensity and help repair damaged relationships. However, robustness mechanisms can also have indirect effects on system integrity by facilitating interactions among components. We explore the indirect role that conflict management mechanisms play in the maintenance of social system robustness, using a perturbation technique to ‘knockout’ components responsible for effective conflict management. We explore the effects of knockout on pigtailed macaque (Macaca nemestrina) social organization, using a captive group of 84 individuals. This system is ideal in addressing this question because there is heterogeneity in performance of conflict management. Consequently, conflict managers can be easily removed without disrupting other control structures. We find that powerful conflict managers are essential in maintaining social order for the benefit of all members of society. We show that knockout of components responsible for conflict management results in system destabilization by significantly increasing mean levels of conflict and aggression, decreasing socio-positive interaction and decreasing the operation of repair mechanisms. PMID:16024369

Verification of fault-tolerant clock synchronization systems. M.S. Thesis - College of William and Mary, 1992

NASA Technical Reports Server (NTRS)

Miner, Paul S.

1993-01-01

A critical function in a fault-tolerant computer architecture is the synchronization of the redundant computing elements. The synchronization algorithm must include safeguards to ensure that failed components do not corrupt the behavior of good clocks. Reasoning about fault-tolerant clock synchronization is difficult because of the possibility of subtle interactions involving failed components. Therefore, mechanical proof systems are used to ensure that the verification of the synchronization system is correct. In 1987, Schneider presented a general proof of correctness for several fault-tolerant clock synchronization algorithms. Subsequently, Shankar verified Schneider's proof by using the mechanical proof system EHDM. This proof ensures that any system satisfying its underlying assumptions will provide Byzantine fault-tolerant clock synchronization. The utility of Shankar's mechanization of Schneider's theory for the verification of clock synchronization systems is explored. Some limitations of Shankar's mechanically verified theory were encountered. With minor modifications to the theory, a mechanically checked proof is provided that removes these limitations. The revised theory also allows for proven recovery from transient faults. Use of the revised theory is illustrated with the verification of an abstract design of a clock synchronization system.

Direct Visualization of Mechanical Beats by Means of an Oscillating Smartphone

NASA Astrophysics Data System (ADS)

Giménez, Marcos H.; Salinas, Isabel; Monsoriu, Juan A.; Castro-Palacio, Juan C.

2017-10-01

The resonance phenomenon is widely known in physics courses. Qualitatively speaking, resonance takes place in a driven oscillating system whenever the frequency approaches the natural frequency, resulting in maximal oscillatory amplitude. Very closely related to resonance is the phenomenon of mechanical beating, which occurs when the driving and natural frequencies of the system are slightly different. The frequency of the beat is just the difference of the natural and driving frequencies. Beats are very familiar in acoustic systems. There are several works in this journal on visualizing the beats in acoustic systems. For instance, the microphone and the speaker of two mobile devices were used in previous work to analyze the acoustic beats produced by two signals of close frequencies. The formation of beats can also be visualized in mechanical systems, such as a mass-spring system or a double-driven string. Here, the mechanical beats in a smartphone-spring system are directly visualized in a simple way. The frequency of the beats is measured by means of the acceleration sensor of a smartphone, which hangs from a spring attached to a mechanical driver. This laboratory experiment is suitable for both high school and first-year university physics courses.

Modelling Systemic Iron Regulation during Dietary Iron Overload and Acute Inflammation: Role of Hepcidin-Independent Mechanisms.

PubMed

Enculescu, Mihaela; Metzendorf, Christoph; Sparla, Richard; Hahnel, Maximilian; Bode, Johannes; Muckenthaler, Martina U; Legewie, Stefan

2017-01-01

Systemic iron levels must be maintained in physiological concentrations to prevent diseases associated with iron deficiency or iron overload. A key role in this process plays ferroportin, the only known mammalian transmembrane iron exporter, which releases iron from duodenal enterocytes, hepatocytes, or iron-recycling macrophages into the blood stream. Ferroportin expression is tightly controlled by transcriptional and post-transcriptional mechanisms in response to hypoxia, iron deficiency, heme iron and inflammatory cues by cell-autonomous and systemic mechanisms. At the systemic level, the iron-regulatory hormone hepcidin is released from the liver in response to these cues, binds to ferroportin and triggers its degradation. The relative importance of individual ferroportin control mechanisms and their interplay at the systemic level is incompletely understood. Here, we built a mathematical model of systemic iron regulation. It incorporates the dynamics of organ iron pools as well as regulation by the hepcidin/ferroportin system. We calibrated and validated the model with time-resolved measurements of iron responses in mice challenged with dietary iron overload and/or inflammation. The model demonstrates that inflammation mainly reduces the amount of iron in the blood stream by reducing intracellular ferroportin transcription, and not by hepcidin-dependent ferroportin protein destabilization. In contrast, ferroportin regulation by hepcidin is the predominant mechanism of iron homeostasis in response to changing iron diets for a big range of dietary iron contents. The model further reveals that additional homeostasis mechanisms must be taken into account at very high dietary iron levels, including the saturation of intestinal uptake of nutritional iron and the uptake of circulating, non-transferrin-bound iron, into liver. Taken together, our model quantitatively describes systemic iron metabolism and generated experimentally testable predictions for additional ferroportin-independent homeostasis mechanisms.

Modelling Systemic Iron Regulation during Dietary Iron Overload and Acute Inflammation: Role of Hepcidin-Independent Mechanisms

PubMed Central

Sparla, Richard; Hahnel, Maximilian; Bode, Johannes; Muckenthaler, Martina U.; Legewie, Stefan

2017-01-01

Systemic iron levels must be maintained in physiological concentrations to prevent diseases associated with iron deficiency or iron overload. A key role in this process plays ferroportin, the only known mammalian transmembrane iron exporter, which releases iron from duodenal enterocytes, hepatocytes, or iron-recycling macrophages into the blood stream. Ferroportin expression is tightly controlled by transcriptional and post-transcriptional mechanisms in response to hypoxia, iron deficiency, heme iron and inflammatory cues by cell-autonomous and systemic mechanisms. At the systemic level, the iron-regulatory hormone hepcidin is released from the liver in response to these cues, binds to ferroportin and triggers its degradation. The relative importance of individual ferroportin control mechanisms and their interplay at the systemic level is incompletely understood. Here, we built a mathematical model of systemic iron regulation. It incorporates the dynamics of organ iron pools as well as regulation by the hepcidin/ferroportin system. We calibrated and validated the model with time-resolved measurements of iron responses in mice challenged with dietary iron overload and/or inflammation. The model demonstrates that inflammation mainly reduces the amount of iron in the blood stream by reducing intracellular ferroportin transcription, and not by hepcidin-dependent ferroportin protein destabilization. In contrast, ferroportin regulation by hepcidin is the predominant mechanism of iron homeostasis in response to changing iron diets for a big range of dietary iron contents. The model further reveals that additional homeostasis mechanisms must be taken into account at very high dietary iron levels, including the saturation of intestinal uptake of nutritional iron and the uptake of circulating, non-transferrin-bound iron, into liver. Taken together, our model quantitatively describes systemic iron metabolism and generated experimentally testable predictions for additional ferroportin-independent homeostasis mechanisms. PMID:28068331

ATS-6 engineering performance report. Volume:Program and systems summaries: Mechanical and thermal details

NASA Technical Reports Server (NTRS)

Wales, R. O. (Editor)

1981-01-01

The overall mission and spacecraft systems, testing, and operations are summarized. The mechanical subsystems are reviewed, encompassing mechanical design requirements; separation and deployment mechanisms; design and performance evaluation; and the television camera reflector monitor. Thermal control and contamination are discussed in terms of thermal control subsystems, design validation, subsystems performance, the advanced flight experiment, and the quartz-crystal microbalance contamination monitor.

Berthing mechanism final test report and program assessment

NASA Technical Reports Server (NTRS)

1988-01-01

The purpose is to document the testing performed on both hardware and software developed under the Space Station Berthing Mechanisms Program. Testing of the mechanism occurred at three locations. Several system components, e.g., actuators and computer systems, were functionally tested before assembly. A series of post assembly tests were performed. The post assembly tests, as well as the dynamic testing of the mechanism, are presented.

Valuation of Transactive Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hammerstrom, Donald J.; Corbin, Charles D.; Fernandez, Nicholas

2016-05-12

This is a final report from a project funded by the U.S. Department of Energy to formulate and test a methodology for valuation of systems where transaction-based mechanisms coordinate the exchange of value between the system’s actors. Today, the principal commodity being exchanged is electrical energy, and such mechanisms are called transactive energy systems. The authors strove to lay a foundation for meaningful valuations of transactive systems in general, and transactive energy systems as a special case. The word valuation is used in many different ways. This report proposes a valuation methodology that is inclusive of many types of valuations.more » Many will be familiar with cost-benefit valuations, in which both costs and benefits are assessed to determine whether the assets are worth their cost. Another set of valuation methods attempt to optimize an outcome using available resources, as is the case with integrated resource planning. In the end, this report’s methodology was most influenced by and most resembles the integrated-resource-planning approach. Regardless, we wish to enforce the premise that all valuations are comparative and should clearly specify a baseline scenario. A long, annotated list of prior valuation studies and valuation methodologies that influenced this report has been appended to this report. Much research is being conducted today concerning transactive systems, but only a handful of transactive system mechanisms have been formulated and field tested. They are found to be quite diverse, and the documentation of the various mechanisms is uneven in breadth and quality. It is therefore not adequate to simply assert that a valuation scenario includes a transactive system; certain characteristics and qualities of the chosen transactive system mechanism must be defined and stated. The report lists and discusses most of the known transactive system mechanisms. It offers a set of questions that may be used to help specify important characteristics of the transactive system mechanisms, which should be conveyed along with other valuation results. A valuation methodology is proposed. Some abstraction is necessarily retained so that the methodology may be applied for the many purposes of today’s valuations and across grid, building, societal, and other domains. The report’s methodology advocates separation of operational timescales from long-term growth timescales. Operational models are defined as the models that inform impacts within the relatively short, often yearlong, operational time periods. Growth models define how the scenarios evolve from one operational period to the next (e.g., from year to year). We believe the recommended methodology is a critical step toward collaborative community platforms, where analysts and decision makers alike could contribute and borrow content within their expertise. The report then asks, what is unique about valuations when systems become coordinated by transactive systems? In answer, accurate valuations of transactive systems require careful adherence to the dynamic interaction between a system’s responsive elements and the system’s operational objectives. In every transactive system mechanism, elements respond to incentives that become revealed to them, and certain operational objectives become explicitly incentivized by the transactive system mechanism. The transactive system mechanisms define the important coupling between the responsive elements and the system’s objectives.« less

Experimental and analytical investigation of inertial propulsion mechanisms and motion simulation of rigid multi-body mechanical systems

NASA Astrophysics Data System (ADS)

Almesallmy, Mohammed

Methodologies are developed for dynamic analysis of mechanical systems with emphasis on inertial propulsion systems. This work adopted the Lagrangian methodology. Lagrangian methodology is the most efficient classical computational technique, which we call Equations of Motion Code (EOMC). The EOMC is applied to several simple dynamic mechanical systems for easier understanding of the method and to aid other investigators in developing equations of motion of any dynamic system. In addition, it is applied to a rigid multibody system, such as Thomson IPS [Thomson 1986]. Furthermore, a simple symbolic algorithm is developed using Maple software, which can be used to convert any nonlinear n-order ordinary differential equation (ODE) systems into 1st-order ODE system in ready format to be used in Matlab software. A side issue, but equally important, we have started corresponding with the U.S. Patent office to persuade them that patent applications, claiming gross linear motion based on inertial propulsion systems should be automatically rejected. The precedent is rejection of patent applications involving perpetual motion machines.

V-TECS Guide for Tractor Mechanic.

ERIC Educational Resources Information Center

Benson, Robert T.

This guide contains a course outline for a tractor mechanic course. The outline is organized by 15 duties: performing general skills and maintaining and servicing storage battery, ignition circuit, the cooling system, the charging circuit, the starting circuit, gasoline fuel system, diesel fuel system, basic engine, lubrication system, clutches,…

Proceedings of the NATO-Advanced Study Institute on Computer Aided Analysis of Rigid and Flexible Mechanical Systems. Volume 1: Main lectures

NASA Astrophysics Data System (ADS)

Pereira, Manuel S.; Ambrosio, Jorge A. C.

1993-07-01

During the last few years, major scientific progress has been achieved in fields related to computer aided analysis of multibody systems. In view of this progress and recent developments of computer hardware and general purpose software, there is a need to access the current state of art and results from different schools of thought, with the objective of focussing trends in future research. Going back to 1983 when an important NATO-NSF-ARO Advanced Study Institute on Computer Aided Analysis and Optimization of Mechanical Systems was held at the University of Iowa, one may notice that less then 10 years ago the state of art was mainly dwelling on rigid body dynamics. The interest in the dynamic simulation of mechanical systems has steadily increased in recent years coming mainly from the aerospace and automative industries. The development of multibody system analysis formulations have been more recently motivated with the need to include several features such as: real-time simulation capabilities, highly non-linear control devices, work space path planing, active control of machine flexibilities and reliability and accuracy in the analysis results. The need for accurate and efficient analysis tools for design of large and lightweight mechanical systems has driven many research groups in the challenging problem of flexible systems with an increasing interaction with finite element methodologies. Basic approaches to mechanical systems dynamic analysis have recently been presented in several new text books. These publications demonstrate that both recursive and absolute methods still have their proponents to resolve the redundancy encountered in most mechanical systems.

Arrows in Comprehending and Producing Mechanical Diagrams

ERIC Educational Resources Information Center

Heiser, Julie; Tversky, Barbara

2006-01-01

Mechanical systems have structural organizations--parts, and their relations--and functional organizations--temporal, dynamic, and causal processes--which can be explained using text or diagrams. Two experiments illustrate the role of arrows in diagrams of mechanical systems. In Experiment 1, people described diagrams with or without arrows,…

Improved Reliability Models for Mechanical and Electrical Components at Navigation Lock and Dam and Flood Risk Management Facilities

DTIC Science & Technology

2013-04-01

official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT...56 A2 Mechanical system - shafts ...80 A23 Mechanical system – strut spindle pin

Anatomy and Physiology of the Speech Mechanism.

ERIC Educational Resources Information Center

Sheets, Boyd V.

This monograph on the anatomical and physiological aspects of the speech mechanism stresses the importance of a general understanding of the process of verbal communication. Contents include "Positions of the Body,""Basic Concepts Linked with the Speech Mechanism,""The Nervous System,""The Respiratory System--Sound-Power Source,""The…

Deployment Mechanism for Thermal Pointing System

NASA Technical Reports Server (NTRS)

Koski, Kraig

2014-01-01

The Deployment Mechanism for the Total and Spectral Solar Irradiance Sensor (TSIS) is responsible for bringing the Thermal Pointing System (TPS) from its stowed, launch locked position to the on-orbit deployed, operational position. The Deployment Mechanism also provides structural support for the TSIS optical bench and two-axis gimbal. An engineering model of the Deployment Mechanism has been environmentally qualified and life tested. This paper will give an overview of the TSIS mission and then describe the development, design, and testing of the Deployment Mechanism.

System precisely controls oscillation of vibrating mass

NASA Technical Reports Server (NTRS)

Hancock, D. J.

1967-01-01

System precisely controls the sinusoidal amplitude of a vibrating mechanical mass. Using two sets of coils, the system regulates the drive signal amplitude at the precise level to maintain the mechanical mass when it reaches the desired vibration amplitude.

The design of a mechanical referencing system for the rear drum of the Longwall Shearer Coal Miner

NASA Technical Reports Server (NTRS)

Jones, E. W.; Yang, T. C. H.

1981-01-01

The design of two systems which reference the position of a longwall shearer coal miner to the mine roof of the present cut and of the last cut are presented. This system is part of an automation system that will guide the rear cutting drum in such a manner that the total depth of cut remains constant even though the front drum may be following an undulating roof profile. The rear drum referencing mechanism continually monitors the distance from the mine roof to the floor for the present cut. This system provides a signal to control a constant depth of cut. The last cut follower mechanism continually monitors the distance from the mine roof of the prior cut to the cutting drum. This latter system provides a signal to minimize the step height in the roof between cuts. The dynamic response of this hydraulic-pneumatic and mechanical system is analyzed to determine accumulator size and precharge pressure.

System identification of closed-loop cardiovascular control: effects of posture and autonomic blockade

NASA Technical Reports Server (NTRS)

Mullen, T. J.; Appel, M. L.; Mukkamala, R.; Mathias, J. M.; Cohen, R. J.

1997-01-01

We applied system identification to the analysis of fluctuations in heart rate (HR), arterial blood pressure (ABP), and instantaneous lung volume (ILV) to characterize quantitatively the physiological mechanisms responsible for the couplings between these variables. We characterized two autonomically mediated coupling mechanisms [the heart rate baroreflex (HR baroreflex) and respiratory sinus arrhythmia (ILV-HR)] and two mechanically mediated coupling mechanisms [the blood pressure wavelet generated with each cardiac contraction (circulatory mechanics) and the direct mechanical effects of respiration on blood pressure (ILV-->ABP)]. We evaluated the method in humans studied in the supine and standing postures under control conditions and under conditions of beta-sympathetic and parasympathetic pharmacological blockades. Combined beta-sympathetic and parasympathetic blockade abolished the autonomically mediated couplings while preserving the mechanically mediated coupling. Selective autonomic blockade and postural changes also altered the couplings in a manner consistent with known physiological mechanisms. System identification is an "inverse-modeling" technique that provides a means for creating a closed-loop model of cardiovascular regulation for an individual subject without altering the underlying physiological control mechanisms.

Research on offense and defense technology for iOS kernel security mechanism

NASA Astrophysics Data System (ADS)

Chu, Sijun; Wu, Hao

2018-04-01

iOS is a strong and widely used mobile device system. It's annual profits make up about 90% of the total profits of all mobile phone brands. Though it is famous for its security, there have been many attacks on the iOS operating system, such as the Trident apt attack in 2016. So it is important to research the iOS security mechanism and understand its weaknesses and put forward targeted protection and security check framework. By studying these attacks and previous jailbreak tools, we can see that an attacker could only run a ROP code and gain kernel read and write permissions based on the ROP after exploiting kernel and user layer vulnerabilities. However, the iOS operating system is still protected by the code signing mechanism, the sandbox mechanism, and the not-writable mechanism of the system's disk area. This is far from the steady, long-lasting control that attackers expect. Before iOS 9, breaking these security mechanisms was usually done by modifying the kernel's important data structures and security mechanism code logic. However, after iOS 9, the kernel integrity protection mechanism was added to the 64-bit operating system and none of the previous methods were adapted to the new versions of iOS [1]. But this does not mean that attackers can not break through. Therefore, based on the analysis of the vulnerability of KPP security mechanism, this paper implements two possible breakthrough methods for kernel security mechanism for iOS9 and iOS10. Meanwhile, we propose a defense method based on kernel integrity detection and sensitive API call detection to defense breakthrough method mentioned above. And we make experiments to prove that this method can prevent and detect attack attempts or invaders effectively and timely.

Fritz London and the scale of quantum mechanisms

NASA Astrophysics Data System (ADS)

Monaldi, Daniela

2017-11-01

Fritz London's seminal idea of ;quantum mechanisms of macroscopic scale;, first articulated in 1946, was the unanticipated result of two decades of research, during which London pursued quantum-mechanical explanations of various kinds of systems of particles at different scales. He started at the microphysical scale with the hydrogen molecule, generalized his approach to chemical bonds and intermolecular forces, then turned to macrophysical systems like superconductors and superfluid helium. Along this path, he formulated a set of concepts-the quantum mechanism of exchange, the rigidity of the wave function, the role of quantum statistics in multi-particle systems, the possibility of order in momentum space-that eventually coalesced into a new conception of systems of equal particles. In particular, it was London's clarification of Bose-Einstein condensation that enabled him to formulate the notion of superfluids, and led him to the recognition that quantum mechanics was not, as it was commonly assumed, relevant exclusively as a micromechanics.

Two Mechanisms to Avoid Control Conflicts Resulting from Uncoordinated Intent

NASA Technical Reports Server (NTRS)

Mishkin, Andrew H.; Dvorak, Daniel L.; Wagner, David A.; Bennett, Matthew B.

2013-01-01

This software implements a real-time access control protocol that is intended to make all connected users aware of the presence of other connected users, and which of them is currently in control of the system. Here, "in control" means that a single user is authorized and enabled to issue instructions to the system. The software The software also implements a goal scheduling mechanism that can detect situations where plans for the operation of a target system proposed by different users overlap and interact in conflicting ways. In such situations, the system can either simply report the conflict (rejecting one goal or the entire plan), or reschedule the goals in a way that does not conflict. The access control mechanism (and associated control protocol) is unique. Other access control mechanisms are generally intended to authenticate users, or exclude unauthorized access. This software does neither, and would likely depend on having some other mechanism to support those requirements.

[Principles of organization and evolution of systems of regulation of functions].

PubMed

Veselkin, N P; Natochin, Iu V

2010-01-01

Evolution of living organisms is closely connected with evolution of structure of the system of regulations and its mechanisms. The functional ground of regulations is chemical signalization. As early as in unicellular organisms there is a set of signal mechanisms providing their life activity and orientation in space and time. Subsequent evolution of ways of chemical signalization followed the way of development of ways of delivery of chemical signal and development of mechanisms of its regulation. The mechanisms of chemical regulation of the signal interaction is discussed by the example of the specialized system of transduction of signal from neuron to neuron, of effect of hormone on the epithelial cell and modulation of this effect. These mechanisms are considered as the most important ways of the fine and precise adaptation of chemical signalization underlying functioning of physiological systems and organs of the living organism.

Quorum sensing and microbial drug resistance.

PubMed

Chen, Yu-fan; Liu, Shi-yin; Liang, Zhi-bin; Lv, Ming-fa; Zhou, Jia-nuan; Zhang, Lian-hui

2016-10-20

Microbial drug resistance has become a serious problem of global concern, and the evolution and regulatory mechanisms of microbial drug resistance has become a hotspot of research in recent years. Recent studies showed that certain microbial resistance mechanisms are regulated by quorum sensing system. Quorum sensing is a ubiquitous cell-cell communication system in the microbial world, which associates with cell density. High-density microbial cells produce sufficient amount of small signal molecules, activating a range of downstream cellular processes including virulence and drug resistance mechanisms, which increases bacterial drug tolerance and causes infections on host organisms. In this review, the general mechanisms of microbial drug resistance and quorum-sensing systems are summarized with a focus on the association of quorum sensing and chemical signaling systems with microbial drug resistance mechanisms, including biofilm formation and drug efflux pump. The potential use of quorum quenching as a new strategy to control microbial resistance is also discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yuuichi Tooya; Tadahiro Washiya; Kenji Koizumi

Japan Atomic Energy Agency (JAEA) has been leading feasibility study on commercialized fast reactor cycle systems in Japan. In this study, we have proposed a new disassembly technology by mechanical disassembly system that consists of a mechanical cutting step and a wrapper tube pulling step. In the mechanical disassembly system, high durability mechanical tool grinds the wrapper tube (Slit-cut (S/C) operation in circle direction), and then the wrapper tube is pulled out and removed from the fuel assembly. Then the fuel pins are cut (Crop-cut (C/C) operation at entrance nozzle side) and the entrance nozzle is removed. The fuel pinsmore » are transported to the shearing device in next process. The Fundamental tests were carried out with simulated FBR fuel pins and wrapper tube, and cutting performance and wrapper tube pulling performance has been confirmed by engineering scale. As results, we established an efficient disassembly procedure and the fundamental design of mechanical disassembly system. (authors)« less

Evaluation of the upconversion mechanisms in Ho3+-doped crystals: Experiment and theoretical modeling

NASA Astrophysics Data System (ADS)

Osiac, E.; Sokólska, I.; Kück, S.

2002-06-01

The paper compares the mechanisms that enable the upconverted green emission (5S2-->5I8) of the Ho3+ ion under infrared excitation (700-920 nm) in several crystalline hosts (YAlO3, YLiF4, Y3Sc2Ga3O12, and BaY2F8). Parameters involved in the upconversion such as excited-state absorption and cross-relaxation rates were determined from spectroscopic measurements. A system of differential equation (rate equations) was used to describe the upconversion mechanism and was numerically solved. The results were compared with experimental data. A reduction of this system to a three-level ``simplified system'' is presented, which includes only the ground level, the emitting level, and the intermediate level. The differences between the photon-avalanche mechanism and the looping mechanism are discussed and analyzed according to this simplified system.

A Mechanical Coil Insertion System for Endovascular Coil Embolization of Intracranial Aneurysms

PubMed Central

Haraguchi, K.; Miyachi, S.; Matsubara, N.; Nagano, Y.; Yamada, H.; Marui, N.; Sano, A.; Fujimoto, H.; Izumi, T.; Yamanouchi, T.; Asai, T.; Wakabayashi, T.

2013-01-01

Summary Like other fields of medicine, robotics and mechanization might be introduced into endovascular coil embolization of intracranial aneurysms for effective treatment. We have already reported that coil insertion force could be smaller and more stable when the coil delivery wire is driven mechanically at a constant speed. Another background is the difficulty in synchronizing operators' minds and hands when two operators control the microcatheter and the coil respectively. We have therefore developed a mechanical coil insertion system enabling a single operator to insert coils at a fixed speed while controlling the microcatheter. Using our new system, the operator manipulated the microcatheter with both hands and drove the coil using foot switches simultaneously. A delivery wire force sensor previously reported was used concurrently, allowing the operator to detect excessive stress on the wire. In vitro coil embolization was performed using three methods: simple mechanical advance of the coil; simple mechanical advance of the coil with microcatheter control; and driving (forward and backward) of the coil using foot switches in addition to microcatheter control. The system worked without any problems, and did not interfere with any procedures. In experimental coil embolization, delivery wire control using the foot switches as well as microcatheter manipulation helped to achieve successful insertion of coils. This system could offer the possibility of developing safer and more efficient coil embolization. Although we aim at total mechanization and automation of procedures in the future, microcatheter manipulation and synchronized delivery wire control are still indispensable using this system. PMID:23693038

Mechanical Control of Myotendinous Junction Formation and Tendon Differentiation during Development.

PubMed

Valdivia, Mauricio; Vega-Macaya, Franco; Olguín, Patricio

2017-01-01

The development of the musculoskeletal system is a great model to study the interplay between chemical and mechanical inter-tissue signaling in cell adhesion, tissue morphogenesis and differentiation. In both vertebrates and invertebrates (e.g., Drosophila melanogaster ) the formation of muscle-tendon interaction generates mechanical forces which are required for myotendinous junction maturation and tissue differentiation. In addition, these forces must be withstood by muscles and tendons in order to prevent detachment from each other, deformation or even losing their integrity. Extracellular matrix remodeling at the myotendinous junction is key to resist mechanical load generated by muscle contraction. Recent evidences in vertebrates indicate that mechanical forces generated during junction formation regulate chemical signaling leading to extracellular matrix remodeling, however, the mechanotransduction mechanisms associated to this response remains elusive. In addition to extracellular matrix remodeling, the ability of Drosophila tendon-cells to bear mechanical load depends on rearrangement of tendon cell cytoskeleton, thus studying the molecular mechanisms involved in this process is critical to understand the contribution of mechanical forces to the development of the musculoskeletal system. Here, we review recent findings regarding the role of chemical and mechanical signaling in myotendinous junction formation and tendon differentiation, and discuss molecular mechanisms of mechanotransduction that may allow tendon cells to withstand mechanical load during development of the musculoskeletal system.

Finite Element Model Characterization Of Nano-Composite Thermal And Environmental Barrier Coatings

NASA Technical Reports Server (NTRS)

Yamada, Yoshiki; Zhu, Dongming

2011-01-01

Thermal and environmental barrier coatings have been applied for protecting Si based ceramic matrix composite components from high temperature environment in advanced gas turbine engines. It has been found that the delamination and lifetime of T/EBC systems generally depend on the initiation and propagation of surface cracks induced by the axial mechanical load in addition to severe thermal loads. In order to prevent T/EBC systems from surface cracking and subsequent delamination due to mechanical and thermal stresses, T/EBC systems reinforced with nano-composite architectures have showed promise to improve mechanical properties and provide a potential crack shielding mechanism such as crack bridging. In this study, a finite element model (FEM) was established to understand the potential beneficial effects of nano-composites systems such as SiC nanotube-reinforced oxide T/EBC systems.

Electro-mechanical probe positioning system for large volume plasma device

NASA Astrophysics Data System (ADS)

Sanyasi, A. K.; Sugandhi, R.; Srivastava, P. K.; Srivastav, Prabhakar; Awasthi, L. M.

2018-05-01

An automated electro-mechanical system for the positioning of plasma diagnostics has been designed and implemented in a Large Volume Plasma Device (LVPD). The system consists of 12 electro-mechanical assemblies, which are orchestrated using the Modbus communication protocol on 4-wire RS485 communications to meet the experimental requirements. Each assembly has a lead screw-based mechanical structure, Wilson feed-through-based vacuum interface, bipolar stepper motor, micro-controller-based stepper drive, and optical encoder for online positioning correction of probes. The novelty of the system lies in the orchestration of multiple drives on a single interface, fabrication and installation of the system for a large experimental device like the LVPD, in-house developed software, and adopted architectural practices. The paper discusses the design, description of hardware and software interfaces, and performance results in LVPD.

Finite-temperature mechanical instability in disordered lattices.

PubMed

Zhang, Leyou; Mao, Xiaoming

2016-02-01

Mechanical instability takes different forms in various ordered and disordered systems and little is known about how thermal fluctuations affect different classes of mechanical instabilities. We develop an analytic theory involving renormalization of rigidity and coherent potential approximation that can be used to understand finite-temperature mechanical stabilities in various disordered systems. We use this theory to study two disordered lattices: a randomly diluted triangular lattice and a randomly braced square lattice. These two lattices belong to two different universality classes as they approach mechanical instability at T=0. We show that thermal fluctuations stabilize both lattices. In particular, the triangular lattice displays a critical regime in which the shear modulus scales as G∼T(1/2), whereas the square lattice shows G∼T(2/3). We discuss generic scaling laws for finite-T mechanical instabilities and relate them to experimental systems.

IMPACT OF AN UPDATED CARBON BOND MECHANISM ON PREDICTIONS FROM THE CMAQ MODELING SYSTEM: PRELIMINARY ASSESSMENT

EPA Science Inventory

An updated and expanded Carbon Bond mechanism (CB05) has been incorporated into the Community Multiscale Air Quality modeling system to more accurately simulate wintertime, pristine, and high altitude situations. The CB05 mechanism has nearly twice the number of reactions compare...

Plasticity of Intermediate Mechanics Students' Coordinate System Choice

ERIC Educational Resources Information Center

Sayre, Eleanor C.; Wittman, Michael C.

2008-01-01

We investigate the interplay between mathematics and physics resources in intermediate mechanics students. In the mechanics course, the selection and application of coordinate systems is a consistent thread. At the University of Maine, students often start the course with a strong preference to use Cartesian coordinates, in accordance with their…

75 FR 879 - National Semiconductor Corporation Arlington Manufacturing Site Including On-Site Leased Workers...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-06

... Foods, Allied Barton Security, ASIL, ASML and Construction Mechanical Systems Arlington, TX; Amended... leased workers from ASML and Construction Mechanical Systems were employed on-site at the Arlington... Department is amending the certification to include workers leased from ASML and Construction Mechanical...

A Qualitative Analogy for Respiratory Mechanics

ERIC Educational Resources Information Center

Baptista, Vander

2010-01-01

The geometric configuration and mechanical properties of the integral elements of the respiratory system, as well as the modus operandi of the interacting parts in the ventilation process, comprise a hard-to-visualize system, making the mechanics of pulmonary ventilation a confusing topic for students and a difficult task for the teacher. To…

A computerized test system for thermal-mechanical fatigue crack growth

NASA Technical Reports Server (NTRS)

Marchand, N.; Pelloux, R. M.

1986-01-01

A computerized testing system to measure fatigue crack growth under thermal-mechanical fatigue conditions is described. Built around a servohydraulic machine, the system is capable of a push-pull test under stress-controlled or strain-controlled conditions in the temperature range of 25 to 1050 C. Temperature and mechanical strain are independently controlled by the closed-loop system to simulate the complex inservice strain-temperature relationship. A d-c electrical potential method is used to measure crack growth rates. The correction procedure of the potential signal to take into account powerline and RF-induced noises and thermal changes is described. It is shown that the potential drop technique can be used for physical mechanism studies and for modelling crack tip processes.

Mechanical devices: A compilation

NASA Technical Reports Server (NTRS)

1976-01-01

A collection of new technology items that should be of interest to mechanical engineers, machinists, and others who design or work with mechanical devices was described. Section 1 contains articles on several new or modified tools, Section 2 describes a number of specialized mechanical systems, and the last section is devoted to valves, bearings, and other parts that might be used with larger systems. The last patent information available is also given.

Wiring Olfaction: The Cellular and Molecular Mechanisms that Guide the Development of Synaptic Connections from the Nose to the Cortex

PubMed Central

de Castro, Fernando

2009-01-01

Within the central nervous system, the olfactory system fascinates by its developmental and physiological particularities, and is one of the most studied models to understand the mechanisms underlying the guidance of growing axons to their appropriate targets. A constellation of contact-mediated (laminins, CAMs, ephrins, etc.) and secreted mechanisms (semaphorins, slits, growth factors, etc.) are known to play different roles in the establishment of synaptic interactions between the olfactory epithelium, olfactory bulb (OB) and olfactory cortex. Specific mechanisms of this system (including the amazing family of about 1000 different olfactory receptors) have been also proposed. In the last years, different reviews have focused in partial sights, specially in the mechanisms involved in the formation of the olfactory nerve, but a detailed review of the mechanisms implicated in the development of the connections among the different olfactory structures (olfactory epithelium, OB, olfactory cortex) remains to be written. In the present work, we afford this systematic review: the different cellular and molecular mechanisms which rule the formation of the olfactory nerve, the lateral olfactory tract and the intracortical connections, as well as the few data available regarding the accessory olfactory system. These mechanisms are compared, and the implications of the differences and similarities discussed in this fundamental scenario of ontogeny. PMID:20582279

Mechanical dynamics in live cells and fluorescence-based force/tension sensors

PubMed Central

Yang, Chao; Zhang, Xiaohan; Guo, Yichen; Meng, Fanjie; Sachs, Frederick; Guo, Jun

2016-01-01

Three signaling systems play the fundamental roles in modulating cell activities: chemical, electrical, and mechanical. While the former two are well studied, the mechanical signaling system is still elusive because of the lack of methods to measure structural forces in real time at cellular and subcellular levels. Indeed, almost all biological processes are responsive to modulation by mechanical forces that trigger dispersive downstream electrical and biochemical pathways. Communication among the three systems is essential to make cells and tissues receptive to environmental changes. Cells have evolved many sophisticated mechanisms for the generation, perception and transduction of mechanical forces, including motor proteins and mechanosensors. In this review, we introduce some background information about mechanical dynamics in live cells, including the ubiquitous mechanical activity, various types of mechanical stimuli exerted on cells and the different mechanosensors. We also summarize recent results obtained using genetically encoded FRET (fluorescence resonance energy transfer)-based force/tension sensors; a new technique used to measure mechanical forces in structural proteins. The sensors have been incorporated into many specific structural proteins and have measured the force gradients in real time within live cells, tissues, and animals. PMID:25958335

14 CFR 27.923 - Rotor drive system and control mechanism tests.

Code of Federal Regulations, 2011 CFR

2011-01-01

... purpose of this paragraph, an affected power input includes all parts of the rotor drive system which can... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Rotor drive system and control mechanism... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Rotor Drive System § 27...

14 CFR 27.923 - Rotor drive system and control mechanism tests.

Code of Federal Regulations, 2013 CFR

2013-01-01

... purpose of this paragraph, an affected power input includes all parts of the rotor drive system which can... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Rotor drive system and control mechanism... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Rotor Drive System § 27...

Auto Mechanics I. Learning Activity Packets (LAPs). Section C--Engine.

ERIC Educational Resources Information Center

Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

This document contains five learning activity packets (LAPs) that outline the study activities for the "engine" instructional area for an Auto Mechanics I course. The five LAPs cover the following topics: basic engine principles, cooling system, engine lubrication system, exhaust system, and fuel system. Each LAP contains a cover sheet…

Using magnetic resonance elastography to assess the dynamic mechanical properties of cartilage

NASA Astrophysics Data System (ADS)

Lopez, Orlando; Amrami, Kimberly; Rossman, Phillip; Ehman, Richard L.

2004-04-01

This work explored the feasibility of using Magnetic Resonance Elastography (MRE) technology to enable in vitro quantification of dynamic mechanical behavior of cartilage through its thickness. A customized system for MRE of cartilage was designed to include components for adequate generation and detection of high frequency mechanical shear waves within small and stiff materials. The system included components for mechanical excitation, motion encoding, and imaging of small samples. Limitations in sensitivity to motion encoding of high frequency propagating mechanical waves using a whole body coil (i.e. Gmax = 2.2 G/cm) required the design of a local gradient coil system to achieve a gain in gradient strength of at least 5 times. The performance of the new system was tested using various cartilage-mimicking phantom materials. MRE of a stiff 5% agar gelatin phantom demonstrated gains in sensitivity to motion encoding of high frequency mechanical waves in cartilage like materials. MRE of fetal bovine cartilage samples yielded a distribution of shear stiffness within the thickness of the cartilage similar to values found in the literature, hence, suggesting the feasibility of using MRE to non-invasively and directly assess the dynamic mechanical properties of cartilage.

Understanding aneuploidy in cancer through the lens of system inheritance, fuzzy inheritance and emergence of new genome systems.

PubMed

Ye, Christine J; Regan, Sarah; Liu, Guo; Alemara, Sarah; Heng, Henry H

2018-01-01

In the past 15 years, impressive progress has been made to understand the molecular mechanism behind aneuploidy, largely due to the effort of using various -omics approaches to study model systems (e.g. yeast and mouse models) and patient samples, as well as the new realization that chromosome alteration-mediated genome instability plays the key role in cancer. As the molecular characterization of the causes and effects of aneuploidy progresses, the search for the general mechanism of how aneuploidy contributes to cancer becomes increasingly challenging: since aneuploidy can be linked to diverse molecular pathways (in regards to both cause and effect), the chances of it being cancerous is highly context-dependent, making it more difficult to study than individual molecular mechanisms. When so many genomic and environmental factors can be linked to aneuploidy, and most of them not commonly shared among patients, the practical value of characterizing additional genetic/epigenetic factors contributing to aneuploidy decreases. Based on the fact that cancer typically represents a complex adaptive system, where there is no linear relationship between lower-level agents (such as each individual gene mutation) and emergent properties (such as cancer phenotypes), we call for a new strategy based on the evolutionary mechanism of aneuploidy in cancer, rather than continuous analysis of various individual molecular mechanisms. To illustrate our viewpoint, we have briefly reviewed both the progress and challenges in this field, suggesting the incorporation of an evolutionary-based mechanism to unify diverse molecular mechanisms. To further clarify this rationale, we will discuss some key concepts of the genome theory of cancer evolution, including system inheritance, fuzzy inheritance, and cancer as a newly emergent cellular system. Illustrating how aneuploidy impacts system inheritance, fuzzy inheritance and the emergence of new systems is of great importance. Such synthesis encourages efforts to apply the principles/approaches of complex adaptive systems to ultimately understand aneuploidy in cancer.

ISS Interface Mechanisms and their Heritage

NASA Technical Reports Server (NTRS)

Cook, John G.; Aksamentov, Valery; Hoffman, Thomas; Bruner, Wes

2011-01-01

The International Space Station, by nurturing technological development of a variety of pressurized and unpressurized interface mechanisms fosters "competition at the technology level". Such redundancy and diversity allows for the development and testing of mechanisms that might be used for future exploration efforts. The International Space Station, as a test-bed for exploration, has 4 types of pressurized interfaces between elements and 6 unpressurized attachment mechanisms. Lessons learned from the design, test and operations of these mechanisms will help inform the design for a new international standard pressurized docking mechanism for the NASA Docking System. This paper will examine the attachment mechanisms on the ISS and their attributes. It will also look ahead at the new NASA docking system and trace its lineage to heritage mechanisms.

Mechanically assisted liquid lens zoom system for mobile phone cameras

NASA Astrophysics Data System (ADS)

Wippermann, F. C.; Schreiber, P.; Bräuer, A.; Berge, B.

2006-08-01

Camera systems with small form factor are an integral part of today's mobile phones which recently feature auto focus functionality. Ready to market solutions without moving parts have been developed by using the electrowetting technology. Besides virtually no deterioration, easy control electronics and simple and therefore cost-effective fabrication, this type of liquid lenses enables extremely fast settling times compared to mechanical approaches. As a next evolutionary step mobile phone cameras will be equipped with zoom functionality. We present first order considerations for the optical design of a miniaturized zoom system based on liquid-lenses and compare it to its mechanical counterpart. We propose a design of a zoom lens with a zoom factor of 2.5 considering state-of-the-art commercially available liquid lens products. The lens possesses auto focus capability and is based on liquid lenses and one additional mechanical actuator. The combination of liquid lenses and a single mechanical actuator enables extremely short settling times of about 20ms for the auto focus and a simplified mechanical system design leading to lower production cost and longer life time. The camera system has a mechanical outline of 24mm in length and 8mm in diameter. The lens with f/# 3.5 provides market relevant optical performance and is designed for an image circle of 6.25mm (1/2.8" format sensor).

Medicaid Program; Mechanized Claims Processing and Information Retrieval Systems (90/10). Final rule.

PubMed

2015-12-04

This final rule will extend enhanced funding for Medicaid eligibility systems as part of a state's mechanized claims processing system, and will update conditions and standards for such systems, including adding to and updating current Medicaid Management Information Systems (MMIS) conditions and standards. These changes will allow states to improve customer service and support the dynamic nature of Medicaid eligibility, enrollment, and delivery systems.

Transport of BMAA into Neurons and Astrocytes by System xc.

PubMed

Albano, Rebecca; Lobner, Doug

2018-01-01

The study of the mechanism of β-N-methylamino-L-alanine (BMAA) neurotoxicity originally focused on its effects at the N-methyl-D-aspartate (NMDA) receptor. In recent years, it has become clear that its mechanism of action is more complicated. First, there are certain cell types, such as motor neurons and cholinergic neurons, where the dominate mechanism of toxicity is through action at AMPA receptors. Second, even in cortical neurons where the primary mechanism of toxicity appears to be activation of NMDA receptors, there are other mechanisms involved. We found that along with NMDA receptors, activation of mGLuR5 receptors and effects on the cystine/glutamate antiporter (system x c -) were involved in the toxicity. The effects on system x c - are of particular interest. System x c - mediates the transport of cystine into the cell in exchange for releasing glutamate into the extracellular fluid. By releasing glutamate, system x c - can potentially cause excitotoxicity. However, through providing cystine to the cell, it regulates the levels of cellular glutathione (GSH), the main endogenous intracellular antioxidant, and in this way may protect cells against oxidative stress. We have previously published that BMAA inhibits cystine uptake leading to GSH depletion and had indirect evidence that BMAA is transported into the cells by system x c -. We now present direct evidence that BMAA is transported into both astrocytes and neurons through system x c -. The fact that BMAA is transported by system x c - also provides a mechanism for BMAA to enter brain cells potentially leading to misincorporation into proteins and protein misfolding.

Mechatronics by Analogy and Application to Legged Locomotion

NASA Astrophysics Data System (ADS)

Ragusila, Victor

A new design methodology for mechatronic systems, dubbed as Mechatronics by Analogy (MbA), is introduced and applied to designing a leg mechanism. The new methodology argues that by establishing a similarity relation between a complex system and a number of simpler models it is possible to design the former using the analysis and synthesis means developed for the latter. The methodology provides a framework for concurrent engineering of complex systems while maintaining the transparency of the system behaviour through making formal analogies between the system and those with more tractable dynamics. The application of the MbA methodology to the design of a monopod robot leg, called the Linkage Leg, is also studied. A series of simulations show that the dynamic behaviour of the Linkage Leg is similar to that of a combination of a double pendulum and a spring-loaded inverted pendulum, based on which the system kinematic, dynamic, and control parameters can be designed concurrently. The first stage of Mechatronics by Analogy is a method of extracting significant features of system dynamics through simpler models. The goal is to determine a set of simpler mechanisms with similar dynamic behaviour to that of the original system in various phases of its motion. A modular bond-graph representation of the system is determined, and subsequently simplified using two simplification algorithms. The first algorithm determines the relevant dynamic elements of the system for each phase of motion, and the second algorithm finds the simple mechanism described by the remaining dynamic elements. In addition to greatly simplifying the controller for the system, using simpler mechanisms with similar behaviour provides a greater insight into the dynamics of the system. This is seen in the second stage of the new methodology, which concurrently optimizes the simpler mechanisms together with a control system based on their dynamics. Once the optimal configuration of the simpler system is determined, the original mechanism is optimized such that its dynamic behaviour is analogous. It is shown that, if this analogy is achieved, the control system designed based on the simpler mechanisms can be directly implemented to the more complex system, and their dynamic behaviours are close enough for the system performance to be effectively the same. Finally it is shown that, for the employed objective of fast legged locomotion, the proposed methodology achieves a better design than Reduction-by-Feedback, a competing methodology that uses control layers to simplify the dynamics of the system.

Design and Integration for High Performance Robotic Systems Based on Decomposition and Hybridization Approaches

PubMed Central

Zhang, Dan; Wei, Bin

2017-01-01

Currently, the uses of robotics are limited with respect to performance capabilities. Improving the performance of robotic mechanisms is and still will be the main research topic in the next decade. In this paper, design and integration for improving performance of robotic systems are achieved through three different approaches, i.e., structure synthesis design approach, dynamic balancing approach, and adaptive control approach. The purpose of robotic mechanism structure synthesis design is to propose certain mechanism that has better kinematic and dynamic performance as compared to the old ones. For the dynamic balancing design approach, it is normally accomplished based on employing counterweights or counter-rotations. The potential issue is that more weight and inertia will be included in the system. Here, reactionless based on the reconfiguration concept is put forward, which can address the mentioned problem. With the mechanism reconfiguration, the control system needs to be adapted thereafter. One way to address control system adaptation is by applying the “divide and conquer” methodology. It entails modularizing the functionalities: breaking up the control functions into small functional modules, and from those modules assembling the control system according to the changing needs of the mechanism. PMID:28075360

Modification of the azimuth control system in the LLMC

NASA Astrophysics Data System (ADS)

Li, Binhua; Yang, Lei; Chen, Linfei; Mao, Wei

2000-10-01

A new control system of the azimuth transmission mechanism used in the Lower Latitude Meridian Circle (LLMC) is described in this paper. Because the original azimuth transmission mechanism causes too much vibration during the transposition of the horizontal axis of the instrument, we decided to modify the original system by two ways. One is to modify the lift mechanism and the azimuth transmission mechanism. The other is to replace the original stepper motors with a new type of stepper motor. According to the requirement of the new motor and its sine subdivided microstep driver, the original control system has been modified. The new system has an expansion output board and a new control program compared with the original one. The hardware architecture of the new system is described. The program in the single chip microcontroller is written in ASM, which is composed of 10 subroutines. The program in a host PC is written in C++. The methods using in controlling motors and skills in designing these programs are discussed. Two sketch flow charts of the control program are presented in the paper. Modification of the lift mechanism is also introduced. All this works make the vibration very slight.

System Design of a Natural Gas PEM Fuel Cell Power Plant for Buildings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joe Ferrall, Tim Rehg, Vesna Stanic

2000-09-30

The following conclusions are made based on this analysis effort: (1) High-temperature PEM data are not available; (2) Stack development effort for Phase II is required; (3) System results are by definition preliminary, mostly due to the immaturity of the high-temperature stack; other components of the system are relatively well defined; (4) The Grotthuss conduction mechanism yields the preferred system characteristics; the Grotthuss conduction mechanism is also much less technically mature than the vehicle mechanism; (5) Fuel processor technology is available today and can be procured for Phase II (steam or ATR); (6) The immaturity of high-temperature membrane technology requiresmore » that a robust system design be developed in Phase II that is capable of operating over a wide temperature and pressure range - (a) Unpressurized or Pressurized PEM (Grotthuss mechanism) at 140 C, Highest temperature most favorable, Lowest water requirement most favorable, Pressurized recommended for base loaded operation, Unpressurized may be preferred for load following; (b) Pressurized PEM (vehicle mechanism) at about 100 C, Pressure required for saturation, Fuel cell technology currently available, stack development required. The system analysis and screening evaluation resulted in the identification of the following components for the most promising system: (1) Steam reforming fuel processor; (2) Grotthuss mechanism fuel cell stack operating at 140 C; (3) Means to deliver system waste heat to a cogeneration unit; (4) Pressurized system utilizing a turbocompressor for a base-load power application. If duty cycling is anticipated, the benefits of compression may be offset due to complexity of control. In this case (and even in the base loaded case), the turbocompressor can be replaced with a blower for low-pressure operation.« less

Resources, attitudes and culture: an understanding of the factors that influence the functioning of accountability mechanisms in primary health care settings.

PubMed

Cleary, Susan M; Molyneux, Sassy; Gilson, Lucy

2013-08-16

District level health system governance is recognised as an important but challenging element of health system development in low and middle-income countries. Accountability is a more recent focus in health system debates. Accountability mechanisms are governance tools that seek to regulate answerability between the health system and the community (external accountability) and/or between different levels of the health system (bureaucratic accountability). External accountability has attracted significant attention in recent years, but bureaucratic accountability mechanisms, and the interactions between the two forms of accountability, have been relatively neglected. This is an important gap given that webs of accountability relationships exist within every health system. There is a need to strike a balance between achieving accountability upwards within the health system (for example through information reporting arrangements) while at the same time allowing for the local level innovation that could improve quality of care and patient responsiveness. Using a descriptive literature review, this paper examines the factors that influence the functioning of accountability mechanisms and relationships within the district health system, and draws out the implications for responsiveness to patients and communities. We also seek to understand the practices that might strengthen accountability in ways that improve responsiveness--of the health system to citizens' needs and rights, and of providers to patients. The review highlights the ways in which bureaucratic accountability mechanisms often constrain the functioning of external accountability mechanisms. For example, meeting the expectations of relatively powerful managers further up the system may crowd out efforts to respond to citizens and patients. Organisational cultures characterized by supervision and management systems focused on compliance to centrally defined outputs and targets can constrain front line managers and providers from responding to patient and population priorities. Findings suggest that it is important to limit the potential negative impacts on responsiveness of new bureaucratic accountability mechanisms, and identify how these or other interventions might leverage the shifts in organizational culture necessary to encourage innovation and patient-centered care.

Validation of a robotic balance system for investigations in the control of human standing balance.

PubMed

Luu, Billy L; Huryn, Thomas P; Van der Loos, H F Machiel; Croft, Elizabeth A; Blouin, Jean-Sébastien

2011-08-01

Previous studies have shown that human body sway during standing approximates the mechanics of an inverted pendulum pivoted at the ankle joints. In this study, a robotic balance system incorporating a Stewart platform base was developed to provide a new technique to investigate the neural mechanisms involved in standing balance. The robotic system, programmed with the mechanics of an inverted pendulum, controlled the motion of the body in response to a change in applied ankle torque. The ability of the robotic system to replicate the load properties of standing was validated by comparing the load stiffness generated when subjects balanced their own body to the robot's mechanical load programmed with a low (concentrated-mass model) or high (distributed-mass model) inertia. The results show that static load stiffness was not significantly (p > 0.05) different for standing and the robotic system. Dynamic load stiffness for the robotic system increased with the frequency of sway, as predicted by the mechanics of an inverted pendulum, with the higher inertia being accurately matched to the load properties of the human body. This robotic balance system accurately replicated the physical model of standing and represents a useful tool to simulate the dynamics of a standing person. © 2011 IEEE

Acquisition of Mechanically Assisted Spark Plasma Sintering System for Advanced Research and Education on Functionally Graded Hybrid Materials

DTIC Science & Technology

2012-03-14

Institute. The proposed effort offers a multidisciplinary research program to achieve the topic goals by coupling thermal- acoustic - mechanical flight...optional optical pyrometer .  Single port for standard (mechanical vacuum pump) and high vacuum system. POWER SUPPLY  10,000 amp, 10 VDC pulsed...Amperage TEMPERATURE CONTROL SYSTEM  Ten (10) Type K and five (5) Type C thermocouples with protective flexible sheaths.  Optical Pyrometer

Mechanisms & Other Systems. Stuff That Works! A Technology Curriculum for the Elementary Grades.

ERIC Educational Resources Information Center

Benenson, Gary

This book focuses on devices and systems that transform motion or convert energy. Contents are divided into six chapters: (1) "Appetizers" includes activities that can be done individually to become familiar with the topic of machines and mechanisms; (2) "Concepts" provides a basis for machine and mechanism development; (3)…

4. PULLEY SYSTEM AND CABLE FOR GATELIFTING MECHANISM, MOUNTED ABOVE ...

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

4. PULLEY SYSTEM AND CABLE FOR GATE-LIFTING MECHANISM, MOUNTED ABOVE THE THREE GATE OPENINGS, LOOKING SOUTH/SOUTHEAST. - Washington Water Power Spokane River Upper Falls Hydroelectric Development, Gates & Gate-Lifting Mechanisms, Spokane River, approximately 0.5 mile northeast of intersection of Spokane Falls Boulevard & Post Street, Spokane, Spokane County, WA

Specific features of the control systems of new-modification 310-330-MW steam turbines manufactured by PAO turboatom

NASA Astrophysics Data System (ADS)

Shvetsov, V. L.; Babaev, I. N.

2017-07-01

Principal engineering solutions taken by PAO Turboatom when developing the control systems of the 310-325-MW turbines for thermal power stations are set forth. A schematic diagram of the control system is presented and the designs of the retrofitted basic mechanisms, viz., high-pressure steam-distribution unit and the cutoff valve, are described. It is noted that the accepted principles of designing the control systems allow retaining the following advantages of the latter: use of the condensate as a cheap nonflammable working fluid, valveless switches to control the locking servomotors, a mechanical ring-type turbine trip mechanism (TTM) in combination with an actuator fitted with two double-seated actuator valves to control the pressure in the pulse security lines, and a rotary valve to block the triggering of the actuator valves during successive testing of the TTM rings by filling the oil during the operation of the turbine and the subsequent raising of the above valves. The control systems of the new-modification turbines are based on microprocessor hardware using electromechanical converters to drive every cutoff valve as a universal solution that is not oriented towards a particular manufacturer of the control system electronics. Application of a mechanical turbine trip mechanism is acknowledged as indispensable for unconditional guarantee of the safe operation of the turbines irrespective of the presence of the electronic turbine trip mechanism.

The phenoptosis problem: what is causing the death of an organism? Lessons from acute kidney injury.

PubMed

Zorov, D B; Plotnikov, E Y; Jankauskas, S S; Isaev, N K; Silachev, D N; Zorova, L D; Pevzner, I B; Pulkova, N V; Zorov, S D; Morosanova, M A

2012-07-01

Programmed execution of various cells and intracellular structures is hypothesized to be not the only example of elimination of biological systems - the general mechanism can also involve programmed execution of organs and organisms. Modern rating of programmed cell death mechanisms includes 13 mechanistic types. As for some types, the mechanism of actuation and manifestation of cell execution has been basically elucidated, while the causes and intermediate steps of the process of fatal failure of organs and organisms remain unknown. The analysis of deaths resulting from a sudden heart arrest or multiple organ failure and other acute and chronic pathologies leads to the conclusion of a special role of mitochondria and oxidative stress activating the immune system. Possible mechanisms of mitochondria-mediated induction of the signaling cascades involved in organ failure and death of the organism are discussed. These mechanisms include generation of reactive oxygen species and damage-associated molecular patterns in mitochondria. Some examples of renal failure-induced deaths are presented with mechanisms and settings determined by some hypothetical super system rather than by the kidneys themselves. This system plays the key role in the process of physiological senescence and termination of an organism. The facts presented suggest that it is the immune system involved in mitochondrial signaling that can act as the system responsible for the organism's death.

Mechanisms for Differential Protein Production in Toxin–Antitoxin Systems

PubMed Central

Deter, Heather S.; Jensen, Roderick V.; Mather, William H.; Butzin, Nicholas C.

2017-01-01

Toxin–antitoxin (TA) systems are key regulators of bacterial persistence, a multidrug-tolerant state found in bacterial species that is a major contributing factor to the growing human health crisis of antibiotic resistance. Type II TA systems consist of two proteins, a toxin and an antitoxin; the toxin is neutralized when they form a complex. The ratio of antitoxin to toxin is significantly greater than 1.0 in the susceptible population (non-persister state), but this ratio is expected to become smaller during persistence. Analysis of multiple datasets (RNA-seq, ribosome profiling) and results from translation initiation rate calculators reveal multiple mechanisms that ensure a high antitoxin-to-toxin ratio in the non-persister state. The regulation mechanisms include both translational and transcriptional regulation. We classified E. coli type II TA systems into four distinct classes based on the mechanism of differential protein production between toxin and antitoxin. We find that the most common regulation mechanism is translational regulation. This classification scheme further refines our understanding of one of the fundamental mechanisms underlying bacterial persistence, especially regarding maintenance of the antitoxin-to-toxin ratio. PMID:28677629

Elastic Multi-scale Mechanisms: Computation and Biological Evolution.

PubMed

Diaz Ochoa, Juan G

2018-01-01

Explanations based on low-level interacting elements are valuable and powerful since they contribute to identify the key mechanisms of biological functions. However, many dynamic systems based on low-level interacting elements with unambiguous, finite, and complete information of initial states generate future states that cannot be predicted, implying an increase of complexity and open-ended evolution. Such systems are like Turing machines, that overlap with dynamical systems that cannot halt. We argue that organisms find halting conditions by distorting these mechanisms, creating conditions for a constant creativity that drives evolution. We introduce a modulus of elasticity to measure the changes in these mechanisms in response to changes in the computed environment. We test this concept in a population of predators and predated cells with chemotactic mechanisms and demonstrate how the selection of a given mechanism depends on the entire population. We finally explore this concept in different frameworks and postulate that the identification of predictive mechanisms is only successful with small elasticity modulus.

Engineering of arteries in vitro

PubMed Central

Huang, Angela H.; Niklason, Laura E.

2014-01-01

This review will focus on two elements that are essential for functional arterial regeneration in vitro: the mechanical environment and the bioreactors used for tissue growth. The importance of the mechanical environment to embryological development, vascular functionality, and vascular graft regeneration will be discussed. Bioreactors generate mechanical stimuli to simulate the biomechanical environment of the arterial system. This system has been used to reconstruct arterial grafts with appropriate mechanical strength for implantation by controlling the chemical and mechanical environments in which the grafts are grown. Bioreactors are powerful tools to study the effect of mechanical stimuli on extracellular matrix (ECM) architecture and the mechanical properties of engineered vessels. Hence biomimetic systems enable us to optimize chemo-biomechanical culture conditions to regenerate engineered vessels with physiological properties similar to those of native arterial vessels. In addition, this review will introduce and examine various approaches and techniques that have been used to engineer biologically-based vascular grafts, including collagen-based grafts, fibrin-gel grafts, cell sheet engineering, biodegradable polymers, and decellularization of native vessels. PMID:24399290

Power generation systems and methods

NASA Technical Reports Server (NTRS)

Jones, Jack A. (Inventor); Chao, Yi (Inventor)

2011-01-01

A power generation system includes a plurality of submerged mechanical devices. Each device includes a pump that can be powered, in operation, by mechanical energy to output a pressurized output liquid flow in a conduit. Main output conduits are connected with the device conduits to combine pressurized output flows output from the submerged mechanical devices into a lower number of pressurized flows. These flows are delivered to a location remote of the submerged mechanical devices for power generation.

Computational structural mechanics for engine structures

NASA Technical Reports Server (NTRS)

Chamis, Christos C.

1988-01-01

The computational structural mechanics (CSM) program at Lewis encompasses the formulation and solution of structural mechanics problems and the development of integrated software systems to computationally simulate the performance, durability, and life of engine structures. It is structured to supplement, complement, and, whenever possible, replace costly experimental efforts. Specific objectives are to investigate unique advantages of parallel and multiprocessing for reformulating and solving structural mechanics and formulating and solving multidisciplinary mechanics and to develop integrated structural system computational simulators for predicting structural performance, evaluating newly developed methods, and identifying and prioritizing improved or missing methods.

Computational structural mechanics for engine structures

NASA Technical Reports Server (NTRS)

Chamis, Christos C.

1989-01-01

The computational structural mechanics (CSM) program at Lewis encompasses the formulation and solution of structural mechanics problems and the development of integrated software systems to computationally simulate the performance, durability, and life of engine structures. It is structured to supplement, complement, and, whenever possible, replace costly experimental efforts. Specific objectives are to investigate unique advantages of parallel and multiprocessing for reformulating and solving structural mechanics and formulating and solving multidisciplinary mechanics and to develop integrated structural system computational simulators for predicting structural performance, evaluating newly developed methods, and identifying and prioritizing improved or missing methods.

Research and Improvement on Characteristics of Emergency Diesel Generating Set Mechanical Support System in Nuclear Power Plant

NASA Astrophysics Data System (ADS)

Zhe, Yang

2017-06-01

There are often mechanical problems of emergency power generation units in nuclear power plant, which bring a great threat to nuclear safety. Through analyzing the influence factors caused by mechanical failure, the existing defects of the design of mechanical support system are determined, and the design idea has caused the direction misleading in the field of maintenance and transformation. In this paper, research analysis is made on basic support design of diesel generator set, main pipe support design and important components of supercharger support design. And this paper points out the specific design flaws and shortcomings, and proposes targeted improvement program. Through the implementation of improvement programs, vibration level of unit and mechanical failure rate are reduced effectively. At the same time, it also provides guidance for design, maintenance and renovation of diesel generator mechanical support system of nuclear power plants in the future.

Mechanical Designs for Inorganic Stretchable Circuits in Soft Electronics.

PubMed

Wang, Shuodao; Huang, Yonggang; Rogers, John A

2015-09-01

Mechanical concepts and designs in inorganic circuits for different levels of stretchability are reviewed in this paper, through discussions of the underlying mechanics and material theories, fabrication procedures for the constituent microscale/nanoscale devices, and experimental characterization. All of the designs reported here adopt heterogeneous structures of rigid and brittle inorganic materials on soft and elastic elastomeric substrates, with mechanical design layouts that isolate large deformations to the elastomer, thereby avoiding potentially destructive plastic strains in the brittle materials. The overall stiffnesses of the electronics, their stretchability, and curvilinear shapes can be designed to match the mechanical properties of biological tissues. The result is a class of soft stretchable electronic systems that are compatible with traditional high-performance inorganic semiconductor technologies. These systems afford promising options for applications in portable biomedical and health-monitoring devices. Mechanics theories and modeling play a key role in understanding the underlining physics and optimization of these systems.

Mechanical Designs for Inorganic Stretchable Circuits in Soft Electronics

PubMed Central

Wang, Shuodao; Huang, Yonggang; Rogers, John A.

2016-01-01

Mechanical concepts and designs in inorganic circuits for different levels of stretchability are reviewed in this paper, through discussions of the underlying mechanics and material theories, fabrication procedures for the constituent microscale/nanoscale devices, and experimental characterization. All of the designs reported here adopt heterogeneous structures of rigid and brittle inorganic materials on soft and elastic elastomeric substrates, with mechanical design layouts that isolate large deformations to the elastomer, thereby avoiding potentially destructive plastic strains in the brittle materials. The overall stiffnesses of the electronics, their stretchability, and curvilinear shapes can be designed to match the mechanical properties of biological tissues. The result is a class of soft stretchable electronic systems that are compatible with traditional high-performance inorganic semiconductor technologies. These systems afford promising options for applications in portable biomedical and health-monitoring devices. Mechanics theories and modeling play a key role in understanding the underlining physics and optimization of these systems. PMID:27668126

Operational Management of Area Environment.

ERIC Educational Resources Information Center

Sprague, George W.

Three phases leading to the automation of the mechanical building systems on the Harvard campus are described. The systems allow a single operator to monitor and control all the mechanical systems, plus fire, flood, and security alarms, for all buildings in a large area of the campus. (JT)

Lather-Interior Systems Mechanic Program. Apprenticeship Training.

ERIC Educational Resources Information Center

Alberta Learning, Edmonton. Apprenticeship and Industry Training.

This document presents information about the apprenticeship training program of Alberta, Canada, in general and the lather-interior systems mechanic program in particular. The first part of the document discusses the following items: Alberta's apprenticeship and industry training system; the apprenticeship and industry training committee…

A Mechanism for Anonymous Credit Card Systems

NASA Astrophysics Data System (ADS)

Tamura, Shinsuke; Yanase, Tatsuro

This paper proposes a mechanism for anonymous credit card systems, in which each credit card holder can conceal individual transactions from the credit card company, while enabling the credit card company to calculate the total expenditures of transactions of individual card holders during specified periods, and to identify card holders who executed dishonest transactions. Based on three existing mechanisms, i.e. anonymous authentication, blind signature and secure statistical data gathering, together with implicit transaction links proposed here, the proposed mechanism enables development of anonymous credit card systems without assuming any absolutely trustworthy entity like tamper resistant devices or organizations faithful both to the credit card company and card holders.

Strain Coupling of a Nitrogen-Vacancy Center Spin to a Diamond Mechanical Oscillator

NASA Astrophysics Data System (ADS)

Teissier, J.; Barfuss, A.; Appel, P.; Neu, E.; Maletinsky, P.

2014-07-01

We report on single electronic spins coupled to the motion of mechanical resonators by a novel mechanism based on crystal strain. Our device consists of single-crystal diamond cantilevers with embedded nitrogen-vacancy center spins. Using optically detected electron spin resonance, we determine the unknown spin-strain coupling constants and demonstrate that our system resides well within the resolved sideband regime. We realize coupling strengths exceeding 10 MHz under mechanical driving and show that our system has the potential to reach strong coupling. Our novel hybrid system forms a resource for future experiments on spin-based cantilever cooling and coherent spin-oscillator coupling.

System and method for bidirectional flow and controlling fluid flow in a conduit

DOEpatents

Ortiz, Marcos German

1999-01-01

A system for measuring bidirectional flow, including backflow, of fluid in a conduit. The system utilizes a structural mechanism to create a pressure differential in the conduit. Pressure sensors are positioned upstream from the mechanism, at the mechanism, and downstream from the mechanism. Data from the pressure sensors are transmitted to a microprocessor or computer, and pressure differential detected between the pressure sensors is then used to calculate the backflow. Control signals may then be generated by the microprocessor or computer to shut off valves located in the conduit, upon the occurrence of backflow, or to control flow, total material dispersed, etc. in the conduit.

A-posteriori error estimation for second order mechanical systems

NASA Astrophysics Data System (ADS)

Ruiner, Thomas; Fehr, Jörg; Haasdonk, Bernard; Eberhard, Peter

2012-06-01

One important issue for the simulation of flexible multibody systems is the reduction of the flexible bodies degrees of freedom. As far as safety questions are concerned knowledge about the error introduced by the reduction of the flexible degrees of freedom is helpful and very important. In this work, an a-posteriori error estimator for linear first order systems is extended for error estimation of mechanical second order systems. Due to the special second order structure of mechanical systems, an improvement of the a-posteriori error estimator is achieved. A major advantage of the a-posteriori error estimator is that the estimator is independent of the used reduction technique. Therefore, it can be used for moment-matching based, Gramian matrices based or modal based model reduction techniques. The capability of the proposed technique is demonstrated by the a-posteriori error estimation of a mechanical system, and a sensitivity analysis of the parameters involved in the error estimation process is conducted.

Animation of multi-flexible body systems and its use in control system design

NASA Technical Reports Server (NTRS)

Juengst, Carl; Stahlberg, Ron

1993-01-01

Animation can greatly assist the structural dynamicist and control system analyst with better understanding of how multi-flexible body systems behave. For multi-flexible body systems, the structural characteristics (mode frequencies, mode shapes, and damping) change, sometimes dramatically with large angles of rotation between bodies. With computer animation, the analyst can visualize these changes and how the system responds to active control forces and torques. A characterization of the type of system we wish to animate is presented. The lack of clear understanding of the above effects was a key element leading to the development of a multi-flexible body animation software package. The resulting animation software is described in some detail here, followed by its application to the control system analyst. Other applications of this software can be determined on an individual need basis. A number of software products are currently available that make the high-speed rendering of rigid body mechanical system simulation possible. However, such options are not available for use in rendering flexible body mechanical system simulations. The desire for a high-speed flexible body visualization tool led to the development of the Flexible Or Rigid Mechanical System (FORMS) software. This software was developed at the Center for Simulation and Design Optimization of Mechanical Systems at the University of Iowa. FORMS provides interactive high-speed rendering of flexible and/or rigid body mechanical system simulations, and combines geometry and motion information to produce animated output. FORMS is designed to be both portable and flexible, and supports a number of different user interfaces and graphical display devices. Additional features have been added to FORMS that allow special visualization results related to the nature of the flexible body geometric representations.

Spacecraft automatic umbilical system

NASA Technical Reports Server (NTRS)

Goldin, R. W.; Jacquemin, G. G.; Johnson, W. H.

1981-01-01

An umbilical system design is described that incorporates all the features specified for a power system to payload interconnect capability. A proof-of-concept prototype of the umbilical system was built to determine experimentally the suitability of the threading characteristics of the ram mechanism and to verify freedom from cross threading. It is concluded that Berthing systems that utilize remote manipulator systems (RMS) can be simplified by using RMS targets, closed circuit TV cameras, tie into the RMS control system, and grapple-fixture and end-effector-like capture and secure mechanisms. To effect a remotely controlled umbilical interconnect in proximity with a manned spacecraft and to provide for extravehicular activity backup and maintenance capabilities, 18 different mechanisms are found to be necessary. The weight impact of proving for maintenance capability in a large multiple connector umbilical system was found to be in the order of +60 percent.

Control design based on dead-zone and leakage adaptive laws for artificial swarm mechanical systems

NASA Astrophysics Data System (ADS)

Zhao, Xiaomin; Chen, Y. H.; Zhao, Han

2017-05-01

We consider the control design of artificial swarm systems with emphasis on four characteristics. First, the agent is made of mechanical components. As a result, the motion of each agent is subject to physical laws that govern mechanical systems. Second, both nonlinearity and uncertainty of the mechanical system are taken into consideration. Third, the ideal agent kinematic performance is treated as a desired d'Alembert constraint. This in turn suggests a creative way of embedding the constraint into the control design. Fourth, two types of adaptive robust control schemes are designed. They both contain leakage and dead-zone. However, one design suggests a trade-off between the amount of leakage and the size of dead-zone, in exchange for a simplified dead-zone structure.

Modelling of long-term and short-term mechanisms of arterial pressure control in the cardiovascular system: an object-oriented approach.

PubMed

Fernandez de Canete, J; Luque, J; Barbancho, J; Munoz, V

2014-04-01

A mathematical model that provides an overall description of both the short- and long-term mechanisms of arterial pressure regulation is presented. Short-term control is exerted through the baroreceptor reflex while renal elimination plays a role in long-term control. Both mechanisms operate in an integrated way over the compartmental model of the cardiovascular system. The whole system was modelled in MODELICA, which uses a hierarchical object-oriented modelling strategy, under the DYMOLA simulation environment. The performance of the controlled system was analysed by simulation in light of the existing hypothesis and validation tests previously performed with physiological data, demonstrating the effectiveness of both regulation mechanisms under physiological and pathological conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Using LEGO Kits to Teach Higher Level Problem Solving Skills in System Dynamics: A Case Study

ERIC Educational Resources Information Center

Wu, Yi; de Vries, Charlotte; Dunsworth, Qi

2018-01-01

System Dynamics is a required course offered to junior Mechanical Engineering students at Penn State Erie, the Behrend College. It addresses the intercoupling dynamics of a wide range of dynamic systems: including mechanical, electrical, fluid, hydraulic, electromechanical, and biomedical systems. This course is challenging for students due to the…

Space Shuttle Orbiter Structures and Mechanisms

NASA Technical Reports Server (NTRS)

Gilmore, Adam L.; Estes, Lynda R.; Eilers, James A.; Logan, Jeffrey S.; Evernden, Brent A.; Decker, William S.; Hagen, Jeffrey D.; Davis, Robert E.; Broughton, James K.; Campbell, Carlisle C.;

HYDRAULIC SERVO CONTROL MECHANISM

DOEpatents

Hussey, R.B.; Gottsche, M.J. Jr.

1963-09-17

A hydraulic servo control mechanism of compact construction and low fluid requirements is described. The mechanism consists of a main hydraulic piston, comprising the drive output, which is connected mechanically for feedback purposes to a servo control piston. A control sleeve having control slots for the system encloses the servo piston, which acts to cover or uncover the slots as a means of controlling the operation of the system. This operation permits only a small amount of fluid to regulate the operation of the mechanism, which, as a result, is compact and relatively light. This mechanism is particuiarly adaptable to the drive and control of control rods in nuclear reactors. (auth)

Synchronization of an optomechanical system to an external drive

NASA Astrophysics Data System (ADS)

Amitai, Ehud; Lörch, Niels; Nunnenkamp, Andreas; Walter, Stefan; Bruder, Christoph

2017-05-01

Optomechanical systems driven by an effective blue-detuned laser can exhibit self-sustained oscillations of the mechanical oscillator. These self-oscillations are a prerequisite for the observation of synchronization. Here, we study the synchronization of the mechanical oscillations to an external reference drive. We study two cases of reference drives: (1) an additional laser applied to the optical cavity; (2) a mechanical drive applied directly to the mechanical oscillator. Starting from a master equation description, we derive a microscopic Adler equation for both cases, valid in the classical regime in which the quantum shot noise of the mechanical self-oscillator does not play a role. Furthermore, we numerically show that, in both cases, synchronization arises also in the quantum regime. The optomechanical system is therefore a good candidate for the study of quantum synchronization.

[Construction of research system for processing mechanism of traditional Chinese medicine based on chemical composition transformation combined with intestinal absorption barrier].

PubMed

Sun, E; Xu, Feng-Juan; Zhang, Zhen-Hai; Wei, Ying-Jie; Tan, Xiao-Bin; Cheng, Xu-Dong; Jia, Xiao-Bin

2014-02-01

Based on practice of Epimedium processing mechanism for many years and integrated multidisciplinary theory and technology, this paper initially constructs the research system for processing mechanism of traditional Chinese medicine based on chemical composition transformation combined with intestinal absorption barrier, which to form an innovative research mode of the " chemical composition changes-biological transformation-metabolism in vitro and in vivo-intestinal absorption-pharmacokinetic combined pharmacodynamic-pharmacodynamic mechanism". Combined with specific examples of Epimedium and other Chinese herbal medicine processing mechanism, this paper also discusses the academic thoughts, research methods and key technologies of this research system, which will be conducive to systematically reveal the modem scientific connotation of traditional Chinese medicine processing, and enrich the theory of Chinese herbal medicine processing.

Development and Preliminary Testing of a High Precision Long Stroke Slit Change Mechanism for the SPICE Instrument

NASA Technical Reports Server (NTRS)

Paciotti, Gabriel; Humphries, Martin; Rottmeier, Fabrice; Blecha, Luc

2014-01-01

In the frame of ESA's Solar Orbiter scientific mission, Almatech has been selected to design, develop and test the Slit Change Mechanism of the SPICE (SPectral Imaging of the Coronal Environment) instrument. In order to guaranty optical cleanliness level while fulfilling stringent positioning accuracies and repeatability requirements for slit positioning in the optical path of the instrument, a linear guiding system based on a double flexible blade arrangement has been selected. The four different slits to be used for the SPICE instrument resulted in a total stroke of 16.5 mm in this linear slit changer arrangement. The combination of long stroke and high precision positioning requirements has been identified as the main design challenge to be validated through breadboard models testing. This paper presents the development of SPICE's Slit Change Mechanism (SCM) and the two-step validation tests successfully performed on breadboard models of its flexible blade support system. The validation test results have demonstrated the full adequacy of the flexible blade guiding system implemented in SPICE's Slit Change Mechanism in a stand-alone configuration. Further breadboard test results, studying the influence of the compliant connection to the SCM linear actuator on an enhanced flexible guiding system design have shown significant enhancements in the positioning accuracy and repeatability of the selected flexible guiding system. Preliminary evaluation of the linear actuator design, including a detailed tolerance analyses, has shown the suitability of this satellite roller screw based mechanism for the actuation of the tested flexible guiding system and compliant connection. The presented development and preliminary testing of the high-precision long-stroke Slit Change Mechanism for the SPICE Instrument are considered fully successful such that future tests considering the full Slit Change Mechanism can be performed, with the gained confidence, directly on a Qualification Model. The selected linear Slit Change Mechanism design concept, consisting of a flexible guiding system driven by a hermetically sealed linear drive mechanism, is considered validated for the specific application of the SPICE instrument, with great potential for other special applications where contamination and high precision positioning are dominant design drivers.

77 FR 16432 - Airworthiness Directives; Cessna Aircraft Company Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-21

... CONTACT: David Fairback, Aerospace Engineer, Mechanical Systems and Propulsion Branch, ACE-116W, FAA... Fairback, Aerospace Engineer, Mechanical Systems and Propulsion Branch, ACE- 116W, FAA, Wichita Aircraft...

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

Twenty six papers are presented from the four sessions of the meeting, dealing with the following subject fields: light mechanical systems and equipment; heavy dynamic mechanical systems and equipment; sturctures; and, relevant experience from various fields. (auth)

Simple display system of mechanical properties of cells and their dispersion.

PubMed

Shimizu, Yuji; Kihara, Takanori; Haghparast, Seyed Mohammad Ali; Yuba, Shunsuke; Miyake, Jun

2012-01-01

The mechanical properties of cells are unique indicators of their states and functions. Though, it is difficult to recognize the degrees of mechanical properties, due to small size of the cell and broad distribution of the mechanical properties. Here, we developed a simple virtual reality system for presenting the mechanical properties of cells and their dispersion using a haptic device and a PC. This system simulates atomic force microscopy (AFM) nanoindentation experiments for floating cells in virtual environments. An operator can virtually position the AFM spherical probe over a round cell with the haptic handle on the PC monitor and feel the force interaction. The Young's modulus of mesenchymal stem cells and HEK293 cells in the floating state was measured by AFM. The distribution of the Young's modulus of these cells was broad, and the distribution complied with a log-normal pattern. To represent the mechanical properties together with the cell variance, we used log-normal distribution-dependent random number determined by the mode and variance values of the Young's modulus of these cells. The represented Young's modulus was determined for each touching event of the probe surface and the cell object, and the haptic device-generating force was calculated using a Hertz model corresponding to the indentation depth and the fixed Young's modulus value. Using this system, we can feel the mechanical properties and their dispersion in each cell type in real time. This system will help us not only recognize the degrees of mechanical properties of diverse cells but also share them with others.

Simple Display System of Mechanical Properties of Cells and Their Dispersion

PubMed Central

Shimizu, Yuji; Kihara, Takanori; Haghparast, Seyed Mohammad Ali; Yuba, Shunsuke; Miyake, Jun

2012-01-01

The mechanical properties of cells are unique indicators of their states and functions. Though, it is difficult to recognize the degrees of mechanical properties, due to small size of the cell and broad distribution of the mechanical properties. Here, we developed a simple virtual reality system for presenting the mechanical properties of cells and their dispersion using a haptic device and a PC. This system simulates atomic force microscopy (AFM) nanoindentation experiments for floating cells in virtual environments. An operator can virtually position the AFM spherical probe over a round cell with the haptic handle on the PC monitor and feel the force interaction. The Young's modulus of mesenchymal stem cells and HEK293 cells in the floating state was measured by AFM. The distribution of the Young's modulus of these cells was broad, and the distribution complied with a log-normal pattern. To represent the mechanical properties together with the cell variance, we used log-normal distribution-dependent random number determined by the mode and variance values of the Young's modulus of these cells. The represented Young's modulus was determined for each touching event of the probe surface and the cell object, and the haptic device-generating force was calculated using a Hertz model corresponding to the indentation depth and the fixed Young's modulus value. Using this system, we can feel the mechanical properties and their dispersion in each cell type in real time. This system will help us not only recognize the degrees of mechanical properties of diverse cells but also share them with others. PMID:22479595

Failure Analysis in Platelet Molded Composite Systems

NASA Astrophysics Data System (ADS)

Kravchenko, Sergii G.

Long-fiber discontinuous composite systems in the form of chopped prepreg tapes provide an advanced, structural grade, molding compound allowing for fabrication of complex three-dimensional components. Understanding of process-structure-property relationship is essential for application of prerpeg platelet molded components, especially because of their possible irregular disordered heterogeneous morphology. Herein, a structure-property relationship was analyzed in the composite systems of many platelets. Regular and irregular morphologies were considered. Platelet-based systems with more ordered morphology possess superior mechanical performance. While regular morphologies allow for a careful inspection of failure mechanisms derived from the morphological characteristics, irregular morphologies are representative of the composite architectures resulting from uncontrolled deposition and molding with chopped prerpegs. Progressive failure analysis (PFA) was used to study the damaged deformation up to ultimate failure in a platelet-based composite system. Computational damage mechanics approaches were utilized to conduct the PFA. The developed computational models granted understanding of how the composite structure details, meaning the platelet geometry and system morphology (geometrical arrangement and orientation distribution of platelets), define the effective mechanical properties of a platelet-molded composite system, its stiffness, strength and variability in properties.

MECHANISMS INVOLVED IN THE ASSOCIATION BETWEEN PERIDONTAL DISEASES AND CARDIOVASCULAR DISEASE

PubMed Central

Teles, Ricardo; Wang, Cun-Yu

2012-01-01

It is now well accepted that besides the cholesterol associated mechanisms of atherogenesis, inflammation plays a crucial role in all stages of the development of the atherosclerotic lesion. This “inflammation hypothesis” raises the possibility that, through systemic elevations of pro-inflammatory cytokines, periodontal diseases might also contribute to systemic inflammation and, therefore, to atherogenesis. In fact, there is evidence that periodontal diseases are associated with higher systemic levels of high-sensitivity C-reactive protein and a low grade systemic inflammation. This phenomenon has been explained based on mechanisms associated with either the infectious or the inflammatory nature of periodontal diseases. The purposes of this article are to review (1) the evidence suggesting a role for oral bacterial species, particularly periodontal pathogens, in atherogenesis; (2) the potential mechanisms explaining an etiological role for oral bacteria in atherosclerosis; (3) the evidence suggesting that periodontal infections are accompanied by a heightened state of systemic inflammation; (4) the potential sources of systemic inflammatory biomarkers associated with periodontal diseases; and (5) the effects of periodontal therapy on systemic inflammatory biomarkers and cardiovascular risk. PMID:21223455

42 CFR 433.138 - Identifying liable third parties.

Code of Federal Regulations, 2013 CFR

2013-10-01

... processing and information retrieval system. Basic requirement—Development of an action plan. (1) If a State has a mechanized claims processing and information retrieval system approved by CMS under subpart C of... plan must be integrated with the mechanized claims processing and information retrieval system. (2) The...

42 CFR 433.138 - Identifying liable third parties.

Code of Federal Regulations, 2014 CFR

2014-10-01

... processing and information retrieval system. Basic requirement—Development of an action plan. (1) If a State has a mechanized claims processing and information retrieval system approved by CMS under subpart C of... plan must be integrated with the mechanized claims processing and information retrieval system. (2) The...

42 CFR 433.138 - Identifying liable third parties.

Code of Federal Regulations, 2012 CFR

2012-10-01

... processing and information retrieval system. Basic requirement—Development of an action plan. (1) If a State has a mechanized claims processing and information retrieval system approved by CMS under subpart C of... plan must be integrated with the mechanized claims processing and information retrieval system. (2) The...

ENVIRONMENTAL POLLUTION AND THE IMMUNE SYSTEM: MECHANISMS OF IMMUNOTOXICITY ACROSS PHYLA

EPA Science Inventory

Environmental pollution and the immune system: Mechanisms of immunotoxicity across phyla. Bob Luebke and Dori Germolec, US EPA, RTP, NC and NIEHS, RTP, NC

Our current understanding of immunotoxicology comes largely from studies done in rodents or using in vitro systems, a...

Aircraft Pneudraulic Systems Mechanic (AFSC 42354).

ERIC Educational Resources Information Center

Air Univ., Gunter AFS, Ala. Extension Course Inst.

This four-volume student text is designed for use by Air Force personnel enrolled in a self-study extension course for aircraft pneudraulic systems mechanics. Covered in the individual volumes are shop administration; fundamentals, materials, and equipment of pneudraulics; pneudraulic components; and pneudraulic systems. Each volume in the set…

System and method of forming nanostructured ferritic alloy

DOEpatents

Dial, Laura Cerully; DiDomizio, Richard; Alinger, Matthew Joseph; Huang, Shenyan

2016-07-26

A system for mechanical milling and a method of mechanical milling are disclosed. The system includes a container, a feedstock, and milling media. The container encloses a processing volume. The feedstock and the milling media are disposed in the processing volume of the container. The feedstock includes metal or alloy powder and a ceramic compound. The feedstock is mechanically milled in the processing volume using metallic milling media that includes a surface portion that has a carbon content less than about 0.4 weight percent.

Hybrid vehicle powertrain system with power take-off driven vehicle accessory

DOEpatents

Beaty, Kevin D.; Bockelmann, Thomas R.; Zou, Zhanijang; Hope, Mark E.; Kang, Xiaosong; Carpenter, Jeffrey L.

2006-09-12

A hybrid vehicle powertrain system includes a first prime mover, a first prime mover driven power transmission mechanism having a power take-off adapted to drive a vehicle accessory, and a second prime mover. The second prime mover is operable to drive the power transmission mechanism alone or in combination with the first prime mover to provide power to the power take-off through the power transmission mechanism. The invention further includes methods for operating a hybrid vehicle powertrain system.

Rule-based mechanisms of learning for intelligent adaptive flight control

NASA Technical Reports Server (NTRS)

Handelman, David A.; Stengel, Robert F.

1990-01-01

How certain aspects of human learning can be used to characterize learning in intelligent adaptive control systems is investigated. Reflexive and declarative memory and learning are described. It is shown that model-based systems-theoretic adaptive control methods exhibit attributes of reflexive learning, whereas the problem-solving capabilities of knowledge-based systems of artificial intelligence are naturally suited for implementing declarative learning. Issues related to learning in knowledge-based control systems are addressed, with particular attention given to rule-based systems. A mechanism for real-time rule-based knowledge acquisition is suggested, and utilization of this mechanism within the context of failure diagnosis for fault-tolerant flight control is demonstrated.

Potential regenerative rehabilitation technology: implications of mechanical stimuli to tissue health

PubMed Central

2014-01-01

Background Mechanical loads induced through muscle contraction, vibration, or compressive forces are thought to modulate tissue plasticity. With the emergence of regenerative medicine, there is a need to understand the optimal mechanical environment (vibration, load, or muscle force) that promotes cellular health. To our knowledge no mechanical system has been proposed to deliver these isolated mechanical stimuli in human tissue. We present the design, performance, and utilization of a new technology that may be used to study localized mechanical stimuli on human tissues. A servo-controlled vibration and limb loading system were developed and integrated into a single instrument to deliver vibration, compression, or muscle contractile loads to a single limb (tibia) in humans. The accuracy, repeatability, transmissibility, and safety of the mechanical delivery system were evaluated on eight individuals with spinal cord injury (SCI). Findings The limb loading system was linear, repeatable, and accurate to less than 5, 1, and 1 percent of full scale, respectively, and transmissibility was excellent. The between session tests on individuals with spinal cord injury (SCI) showed high intra-class correlations (>0.9). Conclusions All tests supported that therapeutic loads can be delivered to a lower limb (tibia) in a safe, accurate, and measureable manner. Future collaborations between engineers and cellular physiologists will be important as research programs strive to determine the optimal mechanical environment for developing cells and tissues in humans. PMID:24894666

Dynamic Federalism and Wind Farm Siting

DTIC Science & Technology

2014-05-18

drawbacks, however. Among these, the mechanical and electromagnetic properties of wind turbines pose significant hazards and complications to U.S...have drawbacks, however. Among these, the mechanical and electromagnetic properties of wind turbines pose significant hazards and complications to...benefits. Wind energy conversion systems are no exception. Wind power systems use elevated turbines to capture mechanical energy from the wind

Valves and other mechanical components and equipment: A compilation

NASA Technical Reports Server (NTRS)

1976-01-01

The articles in this Compilation will be of interest to mechanical engineers, users and designers of machinery, and to those engineers and manufacturers specializing in fluid handling systems. Section 1 describes a number of valves and valve systems. Section 2 contains articles on machinery and mechanical devices that may have applications in a number of different areas.

Engineering Graphene Mechanical Systems

DTIC Science & Technology

2012-07-05

strength material. On the basis of chemical /defect manipulation and recrystallization this technique allows wide-range engineering of mechanical... Engineering Graphene Mechanical Systems Maxim K. Zalalutdinov,† Jeremy T. Robinson,*,† Chad E. Junkermeier,‡ James C. Culbertson, Thomas L. Reinecke...Information ABSTRACT: We report a method to introduce direct bonding between graphene platelets that enables the transformation of a multilayer chemically

State Articulated Instructional Objectives Guide for Occupational Education Programs. State Pilot Model for Automotive Mechanics (DCC V-003) and Automotive Mechanics (High School).

ERIC Educational Resources Information Center

North Carolina State Dept. of Community Colleges, Raleigh.

This articulation instructional objective guide for automotive mechanics contains summary information on fifteen blocks (courses) of instruction. They are introduction to automotive technology; lubrication and vehicle operating maintenance; cooling system maintenance and repair; automobile heater maintenance and repair; braking system maintenance…

Evolution of time-keeping mechanisms: early emergence and adaptation to photoperiod

PubMed Central

Hut, R. A.; Beersma, D. G. M.

2011-01-01

Virtually all species have developed cellular oscillations and mechanisms that synchronize these cellular oscillations to environmental cycles. Such environmental cycles in biotic (e.g. food availability and predation risk) or abiotic (e.g. temperature and light) factors may occur on a daily, annual or tidal time scale. Internal timing mechanisms may facilitate behavioural or physiological adaptation to such changes in environmental conditions. These timing mechanisms commonly involve an internal molecular oscillator (a ‘clock’) that is synchronized (‘entrained’) to the environmental cycle by receptor mechanisms responding to relevant environmental signals (‘Zeitgeber’, i.e. German for time-giver). To understand the evolution of such timing mechanisms, we have to understand the mechanisms leading to selective advantage. Although major advances have been made in our understanding of the physiological and molecular mechanisms driving internal cycles (proximate questions), studies identifying mechanisms of natural selection on clock systems (ultimate questions) are rather limited. Here, we discuss the selective advantage of a circadian system and how its adaptation to day length variation may have a functional role in optimizing seasonal timing. We discuss various cases where selective advantages of circadian timing mechanisms have been shown and cases where temporarily loss of circadian timing may cause selective advantage. We suggest an explanation for why a circadian timing system has emerged in primitive life forms like cyanobacteria and we evaluate a possible molecular mechanism that enabled these bacteria to adapt to seasonal variation in day length. We further discuss how the role of the circadian system in photoperiodic time measurement may explain differential selection pressures on circadian period when species are exposed to changing climatic conditions (e.g. global warming) or when they expand their geographical range to different latitudes or altitudes. PMID:21690131

The Effect of a Mechanical Arm System on Portable Grinder Vibration Emissions.

PubMed

McDowell, Thomas W; Welcome, Daniel E; Warren, Christopher; Xu, Xueyan S; Dong, Ren G

2016-04-01

Mechanical arm systems are commonly used to support powered hand tools to alleviate ergonomic stressors related to the development of workplace musculoskeletal disorders. However, the use of these systems can increase exposure times to other potentially harmful agents such as hand-transmitted vibration. To examine how these tool support systems affect tool vibration, the primary objectives of this study were to characterize the vibration emissions of typical portable pneumatic grinders used for surface grinding with and without a mechanical arm support system at a workplace and to estimate the potential risk of the increased vibration exposure time afforded by the use of these mechanical arm systems. This study also developed a laboratory-based simulated grinding task based on the ISO 28927-1 (2009) standard for assessing grinder vibrations; the simulated grinding vibrations were compared with those measured during actual workplace grinder operations. The results of this study demonstrate that use of the mechanical arm may provide a health benefit by reducing the forces required to lift and maneuver the tools and by decreasing hand-transmitted vibration exposure. However, the arm does not substantially change the basic characteristics of grinder vibration spectra. The mechanical arm reduced the average frequency-weighted acceleration by about 24% in the workplace and by about 7% in the laboratory. Because use of the mechanical arm system can increase daily time-on-task by 50% or more, the use of such systems may actually increase daily time-weighted hand-transmitted vibration exposures in some cases. The laboratory acceleration measurements were substantially lower than the workplace measurements, and the laboratory tool rankings based on acceleration were considerably different than those from the workplace. Thus, it is doubtful that ISO 28927-1 is useful for estimating workplace grinder vibration exposures or for predicting workplace grinder acceleration rank orders. Published by Oxford University Press on behalf of the British Occupational Hygiene Society 2015.

The Effect of a Mechanical Arm System on Portable Grinder Vibration Emissions

PubMed Central

McDowell, Thomas W.; Welcome, Daniel E.; Warren, Christopher; Xu, Xueyan S.; Dong, Ren G.

2016-01-01

Mechanical arm systems are commonly used to support powered hand tools to alleviate ergonomic stressors related to the development of workplace musculoskeletal disorders. However, the use of these systems can increase exposure times to other potentially harmful agents such as hand-transmitted vibration. To examine how these tool support systems affect tool vibration, the primary objectives of this study were to characterize the vibration emissions of typical portable pneumatic grinders used for surface grinding with and without a mechanical arm support system at a workplace and to estimate the potential risk of the increased vibration exposure time afforded by the use of these mechanical arm systems. This study also developed a laboratory-based simulated grinding task based on the ISO 28927-1 (2009) standard for assessing grinder vibrations; the simulated grinding vibrations were compared with those measured during actual workplace grinder operations. The results of this study demonstrate that use of the mechanical arm may provide a health benefit by reducing the forces required to lift and maneuver the tools and by decreasing hand-transmitted vibration exposure. However, the arm does not substantially change the basic characteristics of grinder vibration spectra. The mechanical arm reduced the average frequency-weighted acceleration by about 24% in the workplace and by about 7% in the laboratory. Because use of the mechanical arm system can increase daily time-on-task by 50% or more, the use of such systems may actually increase daily time-weighted hand-transmitted vibration exposures in some cases. The laboratory acceleration measurements were substantially lower than the workplace measurements, and the laboratory tool rankings based on acceleration were considerably different than those from the workplace. Thus, it is doubtful that ISO 28927-1 is useful for estimating workplace grinder vibration exposures or for predicting workplace grinder acceleration rank orders. PMID:26628522

Design of a new type synchronous focusing mechanism

NASA Astrophysics Data System (ADS)

Zhang, Jintao; Tan, Ruijun; Chen, Zhou; Zhang, Yongqi; Fu, Panlong; Qu, Yachen

2018-05-01

Aiming at the dual channel telescopic imaging system composed of infrared imaging system, low-light-level imaging system and image fusion module, In the fusion of low-light-level images and infrared images, it is obvious that using clear source images is easier to obtain high definition fused images. When the target is imaged at 15m to infinity, focusing is needed to ensure the imaging quality of the dual channel imaging system; therefore, a new type of synchronous focusing mechanism is designed. The synchronous focusing mechanism realizes the focusing function through the synchronous translational imaging devices, mainly including the structure of the screw rod nut, the shaft hole coordination structure and the spring steel ball eliminating clearance structure, etc. Starting from the synchronous focusing function of two imaging devices, the structure characteristics of the synchronous focusing mechanism are introduced in detail, and the focusing range is analyzed. The experimental results show that the synchronous focusing mechanism has the advantages of ingenious design, high focusing accuracy and stable and reliable operation.

Modeling of electronic power steering system for IKCO SAMAND vehicle and investigating on its performance via CARSIM software

NASA Astrophysics Data System (ADS)

Haghgoo, Esmail; Zamani, Mohammad; Sharbati, Ali

2017-02-01

The point of this article is introducing the usage of electronic power steering (ESP) system in IKCO SAMAND vehicle and investigating on it's benefit's. Also the operation of electronic steering system and it's performance in IKCO SAMAND vehicle have been described. The optimization of IC engine efficiency and it's fuel consumption have been simulated via ADVISOR software used in MATLAB software. Usually, mechanical steering systems and hydraulic steering systems are producing inside IRAN that the mechanical types have not accepted because of it's too many disadvantages. The hydraulic steering systems, that have been replaced with mechanical types, indeed have the same features with mechanical types but with a difference which they have a hydraulic booster to facilitate the rotation of steering wheel. Beside advantages in hydraulic systems, they are some disadvantages in this system that one of the most important of them is reducing the output power of engine. To restore this power dissipated, we use ESP systems. In this article output diagrams given by software, are showing that IKCO SAMAND vehicle which equipped with ESP system, exerts less torque and power on steering wheel. This improves the safety of driver and also performance of the vehicle at high speeds and reduces fuel consumption beside increasing the efficiency of IC engine.

Bone and Muscle: Interactions beyond Mechanical

PubMed Central

Brotto, Marco

2015-01-01

The musculoskeletal system is significantly more complex than portrayed by traditional reductionist approaches that have focused on and studied the components of this system separately. While bone and skeletal muscle are the two largest tissues within this system, this system also includes tendons, ligaments, cartilage, joints and other connective tissue along with vascular and nervous tissue. Because the main function of this system is locomotion, the mechanical interaction among the major players of this system is essential for the many shapes and forms observed in vertebrates and even in invertebrates. Thus, it is logical that the mechanical coupling theories of musculoskeletal development exert a dominant influence on our understanding of the biology of the musculoskeletal system, because these relationships are relatively easy to observe, measure, and perturb. Certainly much less recognized is the molecular and biochemical interaction among the individual players of the musculoskeletal system. In this brief review article, we first introduce some of the key reasons why the mechanical coupling theory has dominated our view of bone-muscle interactions followed by summarizing evidence for the secretory nature of bones and muscles. Finally, a number of highly physiological questions that cannot be answered by the mechanical theories alone will be raised along with different lines of evidence that support both a genetic and a biochemical communication between bones and muscles. It is hoped that these discussions will stimulate new insights into this fertile and promising new way of defining the relationships between these closely related tissues. Understanding the cellular and molecular mechanisms responsible for biochemical communication between bone and muscle is important not only from a basic research perspective but also as a means to identify potential new therapies for bone and muscle diseases, especially for when they co-exist. PMID:26453500

Safety and Efficacy of Transvenous Lead Extraction Utilizing the Evolution Mechanical Lead Extraction System: A Single-Center Experience.

PubMed

Sharma, Saumya; Ekeruo, Ijeoma A; Nand, Nikita P; Sundara Raman, Ajay; Zhang, Xu; Reddy, Sunil K; Hariharan, Ramesh

2018-02-01

The goal of this study is to assess the safety and efficacy of mechanical lead extraction utilizing the Evolution system. Compared with other techniques commonly used for lead extraction, data regarding the safety and efficacy of mechanical lead extraction using the Evolution system is limited and needs further evaluation. Between June 1, 2009 and September 30, 2016, we retrospectively analyzed 400 consecutive patients who exclusively underwent mechanical lead extraction utilizing the Evolution system. A total of 400 patients underwent mechanical lead extraction of 683 leads. Mean age of extracted leads was 6.77 ± 4.42 years (range 1 to 31 years). The extracted device system was an implantable cardioverter-defibrillator in 274 patients (68.5%) and a pacemaker system in 126 patients (31.5%). Complete lead removal rate was 97% with a clinical success rate of 99.75%. Incomplete lead removal with <4-cm remnant was associated with older leads (lead age >8 years). Failure to achieve clinical success was noted in 1 patient (0.25%). Cardiac papillary avulsion, system-related infection, and cardiac tamponade were the major complications noted in 6 patients (1.5%). Minor complications were encountered in 24 patients (6%), of which hematoma requiring evacuation was the most common minor complication. There were no patient deaths. In our single-center study, lead extractions utilizing the Evolution mechanical lead extraction system were safe and effective and resulted in high clinical and procedural success, with low complication rates and no fatalities. Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Quantum mechanical fragment methods based on partitioning atoms or partitioning coordinates.

PubMed

Wang, Bo; Yang, Ke R; Xu, Xuefei; Isegawa, Miho; Leverentz, Hannah R; Truhlar, Donald G

2014-09-16

Conspectus The development of more efficient and more accurate ways to represent reactive potential energy surfaces is a requirement for extending the simulation of large systems to more complex systems, longer-time dynamical processes, and more complete statistical mechanical sampling. One way to treat large systems is by direct dynamics fragment methods. Another way is by fitting system-specific analytic potential energy functions with methods adapted to large systems. Here we consider both approaches. First we consider three fragment methods that allow a given monomer to appear in more than one fragment. The first two approaches are the electrostatically embedded many-body (EE-MB) expansion and the electrostatically embedded many-body expansion of the correlation energy (EE-MB-CE), which we have shown to yield quite accurate results even when one restricts the calculations to include only electrostatically embedded dimers. The third fragment method is the electrostatically embedded molecular tailoring approach (EE-MTA), which is more flexible than EE-MB and EE-MB-CE. We show that electrostatic embedding greatly improves the accuracy of these approaches compared with the original unembedded approaches. Quantum mechanical fragment methods share with combined quantum mechanical/molecular mechanical (QM/MM) methods the need to treat a quantum mechanical fragment in the presence of the rest of the system, which is especially challenging for those parts of the rest of the system that are close to the boundary of the quantum mechanical fragment. This is a delicate matter even for fragments that are not covalently bonded to the rest of the system, but it becomes even more difficult when the boundary of the quantum mechanical fragment cuts a bond. We have developed a suite of methods for more realistically treating interactions across such boundaries. These methods include redistributing and balancing the external partial atomic charges and the use of tuned fluorine atoms for capping dangling bonds, and we have shown that they can greatly improve the accuracy. Finally we present a new approach that goes beyond QM/MM by combining the convenience of molecular mechanics with the accuracy of fitting a potential function to electronic structure calculations on a specific system. To make the latter practical for systems with a large number of degrees of freedom, we developed a method to interpolate between local internal-coordinate fits to the potential energy. A key issue for the application to large systems is that rather than assigning the atoms or monomers to fragments, we assign the internal coordinates to reaction, secondary, and tertiary sets. Thus, we make a partition in coordinate space rather than atom space. Fits to the local dependence of the potential energy on tertiary coordinates are arrayed along a preselected reaction coordinate at a sequence of geometries called anchor points; the potential energy function is called an anchor points reactive potential. Electrostatically embedded fragment methods and the anchor points reactive potential, because they are based on treating an entire system by quantum mechanical electronic structure methods but are affordable for large and complex systems, have the potential to open new areas for accurate simulations where combined QM/MM methods are inadequate.

Deployment/retraction mechanism for solar maximum mission high gain antenna system

NASA Technical Reports Server (NTRS)

Bennett, N.; Preiswerk, P.

1979-01-01

A mechanism called a deployment/retraction assembly (DRA) which provides not only a stable, but a deployable platform for the high gain antenna system (HGAS) aboard the Solar Maximum Mission (SMM) spacecraft is described. The DRA also has the capability to retract the system upon command.

Development and evaluation of mechanized equipment for installation of the recessed reflective marker (RRM) delineation system. Task A, Design & feasibility analysis

DOT National Transportation Integrated Search

1978-06-01

A plow-resistant recessed reflective marker (RRM) delineation system having a linear tapered profile and which uses a reflector base/reflector unit is proposed. A single-operator mechanized vehicle to install the RRM delineation system is described. ...

Mechatronics as a Technological Basis for an Innovative Learning Environment in Engineering

ERIC Educational Resources Information Center

Garner, Gavin Thomas

2009-01-01

Mechatronic systems that couple mechanical and electrical systems with the help of computer control are forcing a paradigm shift in the design, manufacture, and implementation of mechanical devices. The inherently interdisciplinary nature of these systems generates exciting new opportunities for developing a hands-on, inventive, and…

Error Detection in Mechanized Classification Systems

ERIC Educational Resources Information Center

Hoyle, W. G.

1976-01-01

When documentary material is indexed by a mechanized classification system, and the results judged by trained professionals, the number of documents in disagreement, after suitable adjustment, defines the error rate of the system. In a test case disagreement was 22 percent and, of this 22 percent, the computer correctly identified two-thirds of…

Analysis of Access Control Policies in Operating Systems

ERIC Educational Resources Information Center

Chen, Hong

2009-01-01

Operating systems rely heavily on access control mechanisms to achieve security goals and defend against remote and local attacks. The complexities of modern access control mechanisms and the scale of policy configurations are often overwhelming to system administrators and software developers. Therefore, mis-configurations are common, and the…

Mathematical circulatory system model

NASA Technical Reports Server (NTRS)

Lakin, William D. (Inventor); Stevens, Scott A. (Inventor)

2010-01-01

A system and method of modeling a circulatory system including a regulatory mechanism parameter. In one embodiment, a regulatory mechanism parameter in a lumped parameter model is represented as a logistic function. In another embodiment, the circulatory system model includes a compliant vessel, the model having a parameter representing a change in pressure due to contraction of smooth muscles of a wall of the vessel.

Applications and assessment of QM:QM electronic embedding using generalized asymmetric Mulliken atomic charges.

PubMed

Parandekar, Priya V; Hratchian, Hrant P; Raghavachari, Krishnan

2008-10-14

Hybrid QM:QM (quantum mechanics:quantum mechanics) and QM:MM (quantum mechanics:molecular mechanics) methods are widely used to calculate the electronic structure of large systems where a full quantum mechanical treatment at a desired high level of theory is computationally prohibitive. The ONIOM (our own N-layer integrated molecular orbital molecular mechanics) approximation is one of the more popular hybrid methods, where the total molecular system is divided into multiple layers, each treated at a different level of theory. In a previous publication, we developed a novel QM:QM electronic embedding scheme within the ONIOM framework, where the model system is embedded in the external Mulliken point charges of the surrounding low-level region to account for the polarization of the model system wave function. Therein, we derived and implemented a rigorous expression for the embedding energy as well as analytic gradients that depend on the derivatives of the external Mulliken point charges. In this work, we demonstrate the applicability of our QM:QM method with point charge embedding and assess its accuracy. We study two challenging systems--zinc metalloenzymes and silicon oxide cages--and demonstrate that electronic embedding shows significant improvement over mechanical embedding. We also develop a modified technique for the energy and analytic gradients using a generalized asymmetric Mulliken embedding method involving an unequal splitting of the Mulliken overlap populations to offer improvement in situations where the Mulliken charges may be deficient.

Redox sensing: Orthogonal control in cell cycle and apoptosis signaling

PubMed Central

Jones, Dean P.

2010-01-01

Living systems have three major types of cell signaling systems that are dependent upon high-energy chemicals, redox environment and transmembranal ion gating mechanisms. Development of integrated systems biology descriptions of cell signaling require conceptual models incorporating all three. Recent advances in redox biology show that thiol/disulfide redox systems are regulated under dynamic, non-equilibrium conditions, progressively oxidized with the life cycle of cells and distinct in terms of redox potentials among subcellular compartments. The present article uses these observations as a basis to distinguish “redox-sensing” mechanisms, which are more global biologic redox control mechanisms, from “redox signaling”, which involves conveyance of discrete activating or inactivating signals. Both redox sensing and redox signaling use sulfur switches, especially cysteine (Cys) residues in proteins which are sensitive to reversible oxidation, nitrosylation, glutathionylation, acylation, sulfhydration or metal binding. Unlike specific signaling mechanisms, the redox-sensing mechanisms provide means to globally affect the rates and activities of the high-energy, ion gating and redox-signaling systems by controlling sensitivity, distribution, macromolecular interactions and mobility of signaling proteins. Effects mediated through Cys residues not directly involved in signaling means redox-sensing control can be orthogonal to the signaling mechanisms. This provides a capability to integrate signals according to cell cycle and physiologic state without fundamentally altering the signaling mechanisms. Recent findings that thiol/disulfide pools in humans are oxidized with age, environmental exposures and disease risk suggest that redox-sensing thiols could provide a central mechanistic link in disease development and progression. PMID:20964735

Research Technology

NASA Image and Video Library

2001-08-01

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.

Alstom Francis Turbine Ring Gates: from Retrofitting to Commissioning

NASA Astrophysics Data System (ADS)

A, Nguyen P.; G, Labrecque; M-O, Thibault; M, Bergeron; A, Steinhilber; D, Havard

2014-03-01

The Ring Gate synchronisation system developed by Alstom is new and patented. It uses hydraulic cylinders connected in pairs by a serial connection. The new hydraulic synchronisation system, when compared to the previous mechanical synchronisation system, has several advantages. It is a compact design; it reduces the number of mechanical components as well as maintenance costs. The new system maintains the Ring Gates robustness. The new approach is an evolution from mechanical to hydraulic synchronization assisted by electronic control. The new synchronization system eliminates several mechanical components that used to add wear and friction and which are usually difficult to adjust during maintenance. Tension chains and sprockets and associated controls are eliminated. Through the position sensors, the redundancy of the ring gate synchronization system makes it predictable and reliable. The electronic control compensates for any variation in operation, for example a leak in the hydraulic system. An emergency closing is possible without the electronic control system due to the stiffness of hydraulic serial connection in the hydraulic cylinder pairs. The Ring Gate can work safely against uneven loads and frictions. The development will be reviewed and its application discussed through commissioning results.

Integrated Micro-Power System (IMPS) Development at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Wilt, David; Hepp, Aloysius; Moran, Matt; Jenkins, Phillip; Scheiman, David; Raffaelle, Ryne

2003-01-01

Glenn Research Center (GRC) has a long history of energy related technology developments for large space related power systems, including photovoltaics, thermo-mechanical energy conversion, electrochemical energy storage. mechanical energy storage, power management and distribution and power system design. Recently, many of these technologies have begun to be adapted for small, distributed power system applications or Integrated Micro-Power Systems (IMPS). This paper will describe the IMPS component and system demonstration efforts to date.

Damage assessment of long-range rocket system by electromagnetic pulse weapon

NASA Astrophysics Data System (ADS)

Cao, Lingyu; Liu, Guoqing; Li, Jinming

2017-08-01

This paper analyzes the damage mechanism and characteristics of electromagnetic pulse weapon, establishes the index system of survivability of long-range rocket launcher system, and uses AHP method to establish the combat effectiveness model of long-range rocket missile system. According to the damage mechanism and characteristics of electromagnetic pulse weapon, the damage effect of the remote rocket system is established by using the exponential method to realize the damage efficiency of the remote rocket system.

Microwave power transmission system studies. Volume 3, section 8: Mechanical systems and flight operations

NASA Technical Reports Server (NTRS)

Maynard, O. E.; Brown, W. C.; Edwards, A.; Haley, J. T.; Meltz, G.; Howell, J. M.; Nathan, A.

1975-01-01

The efforts and recommendations associated with preliminary design and concept definition for mechanical systems and flight operations are presented. Technical discussion in the areas of mission analysis, antenna structural concept, configuration analysis, assembly and packaging with associated costs are presented. Technology issues for the control system, structural system, thermal system and assembly including cost and man's role in assembly and maintenance are identified. Background and desired outputs for future efforts are discussed.

Multi-layer plastic/glass microfluidic systems containing electrical and mechanical functionality.

PubMed

Han, Arum; Wang, Olivia; Graff, Mason; Mohanty, Swomitra K; Edwards, Thayne L; Han, Ki-Ho; Bruno Frazier, A

2003-08-01

This paper describes an approach for fabricating multi-layer microfluidic systems from a combination of glass and plastic materials. Methods and characterization results for the microfabrication technologies underlying the process flow are presented. The approach is used to fabricate and characterize multi-layer plastic/glass microfluidic systems containing electrical and mechanical functionality. Hot embossing, heat staking of plastics, injection molding, microstenciling of electrodes, and stereolithography were combined with conventional MEMS fabrication techniques to realize the multi-layer systems. The approach enabled the integration of multiple plastic/glass materials into a single monolithic system, provided a solution for the integration of electrical functionality throughout the system, provided a mechanism for the inclusion of microactuators such as micropumps/valves, and provided an interconnect technology for interfacing fluids and electrical components between the micro system and the macro world.

Development of a body motion interactive system with a weight voting mechanism and computer vision technology

NASA Astrophysics Data System (ADS)

Lin, Chern-Sheng; Chen, Chia-Tse; Shei, Hung-Jung; Lay, Yun-Long; Chiu, Chuang-Chien

2012-09-01

This study develops a body motion interactive system with computer vision technology. This application combines interactive games, art performing, and exercise training system. Multiple image processing and computer vision technologies are used in this study. The system can calculate the characteristics of an object color, and then perform color segmentation. When there is a wrong action judgment, the system will avoid the error with a weight voting mechanism, which can set the condition score and weight value for the action judgment, and choose the best action judgment from the weight voting mechanism. Finally, this study estimated the reliability of the system in order to make improvements. The results showed that, this method has good effect on accuracy and stability during operations of the human-machine interface of the sports training system.

Endocannabinoid mechanism in amphetamine-type stimulant use disorders: A short review.

PubMed

Su, Hang; Zhao, Min

2017-12-01

Recent evidence shows that the endocannabinoid system is involved in amphetamine-type stimulants (ATS) use disorders. To elucidate the role of the endocannabinoid system in ATS addiction, we reviewed results of studies using cannabinoid receptor agonists, antagonists as well as knockout model. The endocannabinoid system seems to play a role in reinstatement and relapse of ATS addiction and ATS-induced psychiatric symptoms. The molecular mechanisms of this system remains unclear, the association with dopamine system in nucleus accumbens is most likely involved. However, the function of the endocannabinoid system in anxiety and anti-anxiety effects induced by ATS is more complicated. These findings suggest that the endocannabinoid system may play an important role in the mechanism of ATS addiction and provide new idea for treating ATS addiction. Copyright © 2017 Elsevier Ltd. All rights reserved.

Deicing and Anti-Icing Unite

NASA Technical Reports Server (NTRS)

2002-01-01

With funding from Glenn's Small Business Innovation Research (SBIR) program, Cox & Company, Inc., built an ice protection system that combines thermal anti-icing and mechanical deicing to keep airfoils (wings and other lifting surfaces) clear of ice. Cox's concept was to combine an anti-icing system with NASA's Electro-Mechanical Expulsion Deicing System, a mechanical deicer. The anti-icing element of this hybrid would reduce the aerodynamic losses associated with deicing systems. The Cox Low Power Ice Protection System is the first new aircraft ice protection system that has been approved by the Federal Aviation Administration for use on a business jet in 40 years. While the system is currently sized for Premier class aircraft, there are no apparent constraints prohibiting its use on aircraft of any size. The company is investigating further applications, such as adapting the system for unmanned aerial vehicles and other military aircraft.

The Intersystem - Internetworking for space systems

NASA Astrophysics Data System (ADS)

Landauer, C.

This paper is a description of the Intersystem, which is a mechanism for internetworking among existing and planned military satellite communication systems. The communication systems interconnected with this mechanism are called member systems, and the interconnected set of communication systems is called the Intersystem. The Intersystem is implemented with higher layer protocols that impose a common organization on the different signaling conventions, so that end users of different systems can communicate with each other. The Intersystem provides its coordination of member system access and resource requests with Intersystem Resource Controllers (IRCs), which are processors that implement the Intersystem protocols and have interfaces to the member systems' own access and resource control mechanisms. The IRCs are connected to each other to form the IRC Subnetwork. Terminals request services from the IRC Subnetwork using the Intersystem Access Control Protocols, and the IRC Subnetwork responses to the requests are coordinated using the RCRC (Resource Controller to Resource Controller) Protocols.

Connections Matter: Social Networks and Lifespan Health in Primate Translational Models

PubMed Central

McCowan, Brenda; Beisner, Brianne; Bliss-Moreau, Eliza; Vandeleest, Jessica; Jin, Jian; Hannibal, Darcy; Hsieh, Fushing

2016-01-01

Humans live in societies full of rich and complex relationships that influence health. The ability to improve human health requires a detailed understanding of the complex interplay of biological systems that contribute to disease processes, including the mechanisms underlying the influence of social contexts on these biological systems. A longitudinal computational systems science approach provides methods uniquely suited to elucidate the mechanisms by which social systems influence health and well-being by investigating how they modulate the interplay among biological systems across the lifespan. In the present report, we argue that nonhuman primate social systems are sufficiently complex to serve as model systems allowing for the development and refinement of both analytical and theoretical frameworks linking social life to health. Ultimately, developing systems science frameworks in nonhuman primate models will speed discovery of the mechanisms that subserve the relationship between social life and human health. PMID:27148103

X-ray pushing of a mechanical microswing.

PubMed

Siria, A; Rodrigues, M S; Dhez, O; Schwartz, W; Torricelli, G; Ledenmat, S; Rochat, N; Auvert, G; Bikondoa, O; Metzger, T H; Wermeille, D; Felici, R; Comin, F; Chevrier, J

2008-11-05

We report here for the first time the combination of x-ray synchrotron light and a micro-electro-mechanical system (MEMS). We show how it is possible to modulate in real time a MEMS mass distribution to induce a nanometric and tunable mechanical oscillation. The quantitative experimental demonstration we present here uses periodic thermal dilatation of a Ge microcrystal attached to a Si microlever, induced by controlled absorption of an intensity modulated x-ray microbeam. The mechanism proposed can be envisaged either for the detection of small heat flux or for the actuation of a mechanical system.

Quid pro quo: a mechanism for fair collaboration in networked systems.

PubMed

Santos, Agustín; Fernández Anta, Antonio; López Fernández, Luis

2013-01-01

Collaboration may be understood as the execution of coordinated tasks (in the most general sense) by groups of users, who cooperate for achieving a common goal. Collaboration is a fundamental assumption and requirement for the correct operation of many communication systems. The main challenge when creating collaborative systems in a decentralized manner is dealing with the fact that users may behave in selfish ways, trying to obtain the benefits of the tasks but without participating in their execution. In this context, Game Theory has been instrumental to model collaborative systems and the task allocation problem, and to design mechanisms for optimal allocation of tasks. In this paper, we revise the classical assumptions of these models and propose a new approach to this problem. First, we establish a system model based on heterogenous nodes (users, players), and propose a basic distributed mechanism so that, when a new task appears, it is assigned to the most suitable node. The classical technique for compensating a node that executes a task is the use of payments (which in most networks are hard or impossible to implement). Instead, we propose a distributed mechanism for the optimal allocation of tasks without payments. We prove this mechanism to be robust evenevent in the presence of independent selfish or rationally limited players. Additionally, our model is based on very weak assumptions, which makes the proposed mechanisms susceptible to be implemented in networked systems (e.g., the Internet).

Wave Phase-Sensitive Transformation of 3d-Straining of Mechanical Fields

NASA Astrophysics Data System (ADS)

Smirnov, I. N.; Speranskiy, A. A.

2015-11-01

It is the area of research of oscillatory processes in elastic mechanical systems. Technical result of innovation is creation of spectral set of multidimensional images which reflect time-correlated three-dimensional vector parameters of metrological, and\\or estimated, and\\or design parameters of oscillations in mechanical systems. Reconstructed images of different dimensionality integrated in various combinations depending on their objective function can be used as homeostatic profile or cybernetic image of oscillatory processes in mechanical systems for an objective estimation of current operational conditions in real time. The innovation can be widely used to enhance the efficiency of monitoring and research of oscillation processes in mechanical systems (objects) in construction, mechanical engineering, acoustics, etc. Concept method of vector vibrometry based on application of vector 3D phase- sensitive vibro-transducers permits unique evaluation of real stressed-strained states of power aggregates and loaded constructions and opens fundamental innovation opportunities: conduct of continuous (on-line regime) reliable monitoring of turboagregates of electrical machines, compressor installations, bases, supports, pipe-lines and other objects subjected to damaging effect of vibrations; control of operational safety of technical systems at all the stages of life cycle including design, test production, tuning, testing, operational use, repairs and resource enlargement; creation of vibro-diagnostic systems of authentic non-destructive control of anisotropic characteristics of materials resistance of power aggregates and loaded constructions under outer effects and operational flaws. The described technology is revolutionary, universal and common for all branches of engineering industry and construction building objects.

System and method for bidirectional flow and controlling fluid flow in a conduit

DOEpatents

Ortiz, M.G.

1999-03-23

A system for measuring bidirectional flow, including backflow, of fluid in a conduit is disclosed. The system utilizes a structural mechanism to create a pressure differential in the conduit. Pressure sensors are positioned upstream from the mechanism, at the mechanism, and downstream from the mechanism. Data from the pressure sensors are transmitted to a microprocessor or computer, and pressure differential detected between the pressure sensors is then used to calculate the backflow. Control signals may then be generated by the microprocessor or computer to shut off valves located in the conduit, upon the occurrence of backflow, or to control flow, total material dispersed, etc. in the conduit. 3 figs.

Anharmonic quantum mechanical systems do not feature phase space trajectories

NASA Astrophysics Data System (ADS)

Oliva, Maxime; Kakofengitis, Dimitris; Steuernagel, Ole

2018-07-01

Phase space dynamics in classical mechanics is described by transport along trajectories. Anharmonic quantum mechanical systems do not allow for a trajectory-based description of their phase space dynamics. This invalidates some approaches to quantum phase space studies. We first demonstrate the absence of trajectories in general terms. We then give an explicit proof for all quantum phase space distributions with negative values: we show that the generation of coherences in anharmonic quantum mechanical systems is responsible for the occurrence of singularities in their phase space velocity fields, and vice versa. This explains numerical problems repeatedly reported in the literature, and provides deeper insight into the nature of quantum phase space dynamics.

Computation and Communication Evaluation of an Authentication Mechanism for Time-Triggered Networked Control Systems

PubMed Central

Martins, Goncalo; Moondra, Arul; Dubey, Abhishek; Bhattacharjee, Anirban; Koutsoukos, Xenofon D.

2016-01-01

In modern networked control applications, confidentiality and integrity are important features to address in order to prevent against attacks. Moreover, network control systems are a fundamental part of the communication components of current cyber-physical systems (e.g., automotive communications). Many networked control systems employ Time-Triggered (TT) architectures that provide mechanisms enabling the exchange of precise and synchronous messages. TT systems have computation and communication constraints, and with the aim to enable secure communications in the network, it is important to evaluate the computational and communication overhead of implementing secure communication mechanisms. This paper presents a comprehensive analysis and evaluation of the effects of adding a Hash-based Message Authentication (HMAC) to TT networked control systems. The contributions of the paper include (1) the analysis and experimental validation of the communication overhead, as well as a scalability analysis that utilizes the experimental result for both wired and wireless platforms and (2) an experimental evaluation of the computational overhead of HMAC based on a kernel-level Linux implementation. An automotive application is used as an example, and the results show that it is feasible to implement a secure communication mechanism without interfering with the existing automotive controller execution times. The methods and results of the paper can be used for evaluating the performance impact of security mechanisms and, thus, for the design of secure wired and wireless TT networked control systems. PMID:27463718

Computation and Communication Evaluation of an Authentication Mechanism for Time-Triggered Networked Control Systems.

PubMed

Martins, Goncalo; Moondra, Arul; Dubey, Abhishek; Bhattacharjee, Anirban; Koutsoukos, Xenofon D

2016-07-25

In modern networked control applications, confidentiality and integrity are important features to address in order to prevent against attacks. Moreover, network control systems are a fundamental part of the communication components of current cyber-physical systems (e.g., automotive communications). Many networked control systems employ Time-Triggered (TT) architectures that provide mechanisms enabling the exchange of precise and synchronous messages. TT systems have computation and communication constraints, and with the aim to enable secure communications in the network, it is important to evaluate the computational and communication overhead of implementing secure communication mechanisms. This paper presents a comprehensive analysis and evaluation of the effects of adding a Hash-based Message Authentication (HMAC) to TT networked control systems. The contributions of the paper include (1) the analysis and experimental validation of the communication overhead, as well as a scalability analysis that utilizes the experimental result for both wired and wireless platforms and (2) an experimental evaluation of the computational overhead of HMAC based on a kernel-level Linux implementation. An automotive application is used as an example, and the results show that it is feasible to implement a secure communication mechanism without interfering with the existing automotive controller execution times. The methods and results of the paper can be used for evaluating the performance impact of security mechanisms and, thus, for the design of secure wired and wireless TT networked control systems.

Immune regulation of systemic hypertension, pulmonary arterial hypertension, and preeclampsia: shared disease mechanisms and translational opportunities.

PubMed

Jafri, Salema; Ormiston, Mark L

2017-12-01

Systemic hypertension, preeclampsia, and pulmonary arterial hypertension (PAH) are diseases of high blood pressure in the systemic or pulmonary circulation. Beyond the well-defined contribution of more traditional pathophysiological mechanisms, such as changes in the renin-angiotensin-aldosterone system, to the development of these hypertensive disorders, there is substantial clinical evidence supporting an important role for inflammation and immunity in the pathogenesis of each of these three conditions. Over the last decade, work in small animal models, bearing targeted deficiencies in specific cytokines or immune cell subsets, has begun to clarify the immune-mediated mechanisms that drive changes in vascular structure and tone in hypertensive disease. By summarizing the clinical and experimental evidence supporting a contribution of the immune system to systemic hypertension, preeclampsia, and PAH, the current review highlights the cellular and molecular pathways that are common to all three hypertensive disorders. These mechanisms are centered on an imbalance in CD4 + helper T cell populations, defined by excessive Th17 responses and impaired T reg activity, as well as the excessive activation or impairment of additional immune cell types, including macrophages, dendritic cells, CD8 + T cells, B cells, and natural killer cells. The identification of common immune mechanisms in systemic hypertension, preeclampsia, and PAH raises the possibility of new therapeutic strategies that target the immune component of hypertension across multiple disorders. Copyright © 2017 the American Physiological Society.

A methodology for identification and control of electro-mechanical actuators

PubMed Central

Tutunji, Tarek A.; Saleem, Ashraf

2015-01-01

Mechatronic systems are fully-integrated engineering systems that are composed of mechanical, electronic, and computer control sub-systems. These integrated systems use electro-mechanical actuators to cause the required motion. Therefore, the design of appropriate controllers for these actuators are an essential step in mechatronic system design. In this paper, a three-stage methodology for real-time identification and control of electro-mechanical actuator plants is presented, tested, and validated. First, identification models are constructed from experimental data to approximate the plants’ response. Second, the identified model is used in a simulation environment for the purpose of designing a suitable controller. Finally, the designed controller is applied and tested on the real plant through Hardware-in-the-Loop (HIL) environment. The described three-stage methodology provides the following practical contributions: • Establishes an easy-to-follow methodology for controller design of electro-mechanical actuators. • Combines off-line and on-line controller design for practical performance. • Modifies the HIL concept by using physical plants with computer control (rather than virtual plants with physical controllers). Simulated and experimental results for two case studies, induction motor and vehicle drive system, are presented in order to validate the proposed methodology. These results showed that electromechanical actuators can be identified and controlled using an easy-to-duplicate and flexible procedure. PMID:26150992

A methodology for identification and control of electro-mechanical actuators.

PubMed

Tutunji, Tarek A; Saleem, Ashraf

2015-01-01

Mechatronic systems are fully-integrated engineering systems that are composed of mechanical, electronic, and computer control sub-systems. These integrated systems use electro-mechanical actuators to cause the required motion. Therefore, the design of appropriate controllers for these actuators are an essential step in mechatronic system design. In this paper, a three-stage methodology for real-time identification and control of electro-mechanical actuator plants is presented, tested, and validated. First, identification models are constructed from experimental data to approximate the plants' response. Second, the identified model is used in a simulation environment for the purpose of designing a suitable controller. Finally, the designed controller is applied and tested on the real plant through Hardware-in-the-Loop (HIL) environment. The described three-stage methodology provides the following practical contributions: •Establishes an easy-to-follow methodology for controller design of electro-mechanical actuators.•Combines off-line and on-line controller design for practical performance.•Modifies the HIL concept by using physical plants with computer control (rather than virtual plants with physical controllers). Simulated and experimental results for two case studies, induction motor and vehicle drive system, are presented in order to validate the proposed methodology. These results showed that electromechanical actuators can be identified and controlled using an easy-to-duplicate and flexible procedure.

Compact scheme for systems of equations applied to fundamental problems of mechanics of continua

NASA Technical Reports Server (NTRS)

Klimkowski, Jerzy Z.

1990-01-01

Compact scheme formulation was used in the treatment of boundary conditions for a system of coupled diffusion and Poisson equations. Models and practical solutions of specific engineering problems arising in solid mechanics, chemical engineering, heat transfer and fuid mechanics are described and analyzed for efficiency and accuracy. Only 2-D cases are discussed and a new method of numerical treatment of boundary conditions common in the fundamental problems of mechanics of continua is presented.

NASA Space Mechanisms Handbook and Reference Guide Expanded Into CD-ROM Set

NASA Technical Reports Server (NTRS)

Fusaro, Robert L.

2002-01-01

Several NASA missions suffered failures and anomalies due to problems in applying space mechanisms technology to specific projects. Research shows that engineers often lack either adequate knowledge of mechanism design or sufficient understanding of how mechanisms affect sensitive systems. The Space Mechanisms Project conducted a Lessons Learned study and published a Space Mechanisms Handbook to help space industry engineers avoid recurring design, qualification, and application problems. The Space Mechanisms Handbook written at the NASA Glenn Research Center details the state-of-the-art in space mechanisms design as of 1998. NASA's objective in developing this Space Mechanisms Handbook was to provide readily accessible information on such areas as space mechanisms design, mechanical component availability and use, testing and qualification of mechanical systems, and a listing of worldwide space mechanisms experts and testing facilities in the United States. This handbook has been expanded into a two-volume CD-ROM set in an Adobe Acrobat format. In addition to the handbook, the CD's include (1) the two volume Space Mechanisms Lessons Learned Study, (2) proceedings from all the NASA hosted Aerospace Mechanisms Symposia held through the year 2000, (3) the Space Materials Handbook, (4) the Lubrication Handbook for the Space Industry, (5) the Structural & Mechanical Systems Long-Life Assurance Design Guidelines, (6) the Space Environments and Effects Source-Book, (7) the Spacecraft Deployable Appendages manual, (8) the Fastener Design Manual, (9) A Manual for Pyrotechnic Design, Development and Qualification, (10) the Report on Alternative Devices to Pyrotechnics on Spacecraft, and (11) Gearing (a manual). In addition, numerous other papers on tribology and lubrication are included.This technical summary of the project provides information on how to obtain the handbook and related information.

Selection of active elements in system reduction of vibration

NASA Astrophysics Data System (ADS)

Bialas, K.

2016-11-01

This work presents non-classical method of design of mechatronic systems. The purpose of this paper is also introduces synthesis of mechatronic system understand as design of mechatronic systems. The synthesis may be applied to modify the already existing systems in order to achieve a desired result. The system was consisted from mechanical and electrical elements. Electrical elements were used as subsystem reducing unwanted vibration of mechanical system. Electrical elements can be realized in the form of coils with movable core. The system was modelled in Matlab Simulink.

Mechanical design and driving mechanism of an isokinetic functional electrical stimulation-based leg stepping trainer.

PubMed

Hamzaid, N A; Fornusek, C; Ruys, A; Davis, G M

2007-12-01

The mechanical design of a constant velocity (isokinetic) leg stepping trainer driven by functional electrical stimulation-evoked muscle contractions was the focus of this paper. The system was conceived for training the leg muscles of neurologically-impaired patients. A commercially available slider crank mechanism for elliptical stepping exercise was adapted to a motorized isokinetic driving mechanism. The exercise system permits constant-velocity pedalling at cadences of 1-60 rev x min(-1). The variable-velocity feature allows low pedalling forces for individuals with very weak leg muscles, yet provides resistance to higher pedalling effort in stronger patients. In the future, the system will be integrated with a computer-controlled neuromuscular stimulator and a feedback control unit to monitor training responses of spinal cord-injured, stroke and head injury patients.

The 10 MWe Solar Thermal Central Receiver Pilot Plant: Solar facilities design integration. Pilot-plant station manual (RADL Item 2-1). Volume 1: System description

NASA Astrophysics Data System (ADS)

1982-09-01

The complete Barstow Solar Pilot Plant is described. The plant requirements and general description are presented, the mechanical, electric power, and control and instrumentation systems as well as civil engineering and structural aspects and the station buildings are described. Included in the mechanical systems are the heliostats, receiver, thermal storage system, beam characterization system, steam, water, nitrogen, and compressed air systems, chemical feed system, fire protection system, drains, sumps and the waste disposal systems, and heating, ventilating, and air conditioning systems.

A dual closed-loop control system for mechanical ventilation.

PubMed

Tehrani, Fleur; Rogers, Mark; Lo, Takkin; Malinowski, Thomas; Afuwape, Samuel; Lum, Michael; Grundl, Brett; Terry, Michael

2004-04-01

Closed-loop mechanical ventilation has the potential to provide more effective ventilatory support to patients with less complexity than conventional ventilation. The purpose of this study was to investigate the effectiveness of an automatic technique for mechanical ventilation. Two closed-loop control systems for mechanical ventilation are combined in this study. In one of the control systems several physiological data are used to automatically adjust the frequency and tidal volume of breaths of a patient. This method, which is patented under US Patent number 4986268, uses the criterion of minimal respiratory work rate to provide the patient with a natural pattern of breathing. The inputs to the system include data representing CO2 and O2 levels of the patient as well as respiratory compliance and airway resistance. The I:E ratio is adjusted on the basis of the respiratory time constant to allow for effective emptying of the lungs in expiration and to avoid intrinsic positive end expiratory pressure (PEEP). This system is combined with another closed-loop control system for automatic adjustment of the inspired fraction of oxygen of the patient. This controller uses the feedback of arterial oxygen saturation of the patient and combines a rapid stepwise control procedure with a proportional-integral-derivative (PID) control algorithm to automatically adjust the oxygen concentration in the patient's inspired gas. The dual closed-loop control system has been examined by using mechanical lung studies, computer simulations and animal experiments. In the mechanical lung studies, the ventilation controller adjusted the breathing frequency and tidal volume in a clinically appropriate manner in response to changes in respiratory mechanics. The results of computer simulations and animal studies under induced disturbances showed that blood gases were returned to the normal physiologic range in less than 25 s by the control system. In the animal experiments understeady-state conditions, the maximum standard deviations of arterial oxygen saturation and the end-tidal partial pressure of CO2 were +/- 1.76% and +/- 1.78 mmHg, respectively. The controller maintained the arterial blood gases within normal limits under steady-state conditions and the transient response of the system was robust under various disturbances. The results of the study have showed that the proposed dual closed-loop technique has effectively controlled mechanical ventilation under different test conditions.

Test Rig for Evaluating Active Turbine Blade Tip Clearance Control Concepts

NASA Technical Reports Server (NTRS)

Lattime, Scott B.; Steinetz, Bruce M.; Robbie, Malcolm G.; Erker, Arthur H.

2004-01-01

The objectives of the research presented in this viewgraph presentation are to 1) Design a mechanical ACC system for HPT tip seal clearance management; 2) Design a test rig to evaluate ACC system concepts. We have focused our efforts on designing mechanical ACC systems that articulate the seal shroud via mechanical linkages connected to actuators that reside outside the extreme environment of the HPT. We opted for this style of design due to a lack of high temperature/low profile actuators that are presently available. We have also selected multiple hydraulic actuators for this first generation ACC system. Fuel-draulic actuators are already a well established technology.

Mechanisms of developmental neurite pruning.

PubMed

Schuldiner, Oren; Yaron, Avraham

2015-01-01

The precise wiring of the nervous system is a combined outcome of progressive and regressive events during development. Axon guidance and synapse formation intertwined with cell death and neurite pruning sculpt the mature circuitry. It is now well recognized that pruning of dendrites and axons as means to refine neuronal networks, is a wide spread phenomena required for the normal development of vertebrate and invertebrate nervous systems. Here we will review the arising principles of cellular and molecular mechanisms of neurite pruning. We will discuss these principles in light of studies in multiple neuronal systems, and speculate on potential explanations for the emergence of neurite pruning as a mechanism to sculpt the nervous system.

2. Photographic copy of engineering drawing showing mechanical systems in ...

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

2. Photographic copy of engineering drawing showing mechanical systems in plan and sections of Test Stand 'E,' including tunnel entrance. California Institute of Technology, Jet Propulsion Laboratory, Plant Engineering 'Bldg. E-60 Mechanical, Solid Propellant Test Stand,' sheet E60/13-4, June 20, 1961. - Jet Propulsion Laboratory Edwards Facility, Test Stand E, Edwards Air Force Base, Boron, Kern County, CA

Net energy output from harvesting small-diameter trees using a mechanized system

Treesearch

Fei Pan; Han-Sup Han; Leonard R. Johnson; William J. Elliot

2008-01-01

What amount of extra energy can be generated after subtracting the total energy consumed to produce the biomass energy? Knowing the ratio between energy output and input is a valid question when highly mechanized systems that consume fossil fuels are used to harvest and transport forest biomass for energy. We estimated the net energy generated from mechanical fuel...

Two speed drive system. [mechanical device for changing speed on rotating vehicle wheel

NASA Technical Reports Server (NTRS)

Burch, J. L. (Inventor)

1972-01-01

A two speed drive system for a wheel of a vehicle by which shifting from one speed to the other is accomplished by the inherent mechanism of the wheel is described. A description of the speed shifting operation is provided and diagrams of the mechanism are included. Possible application to lunar roving vehicles is proposed.

Computational modeling of single-cell mechanics and cytoskeletal mechanobiology.

PubMed

Rajagopal, Vijay; Holmes, William R; Lee, Peter Vee Sin

2018-03-01

Cellular cytoskeletal mechanics plays a major role in many aspects of human health from organ development to wound healing, tissue homeostasis and cancer metastasis. We summarize the state-of-the-art techniques for mathematically modeling cellular stiffness and mechanics and the cytoskeletal components and factors that regulate them. We highlight key experiments that have assisted model parameterization and compare the advantages of different models that have been used to recapitulate these experiments. An overview of feed-forward mechanisms from signaling to cytoskeleton remodeling is provided, followed by a discussion of the rapidly growing niche of encapsulating feedback mechanisms from cytoskeletal and cell mechanics to signaling. We discuss broad areas of advancement that could accelerate research and understanding of cellular mechanobiology. A precise understanding of the molecular mechanisms that affect cell and tissue mechanics and function will underpin innovations in medical device technologies of the future. WIREs Syst Biol Med 2018, 10:e1407. doi: 10.1002/wsbm.1407 This article is categorized under: Models of Systems Properties and Processes > Mechanistic Models Physiology > Mammalian Physiology in Health and Disease Models of Systems Properties and Processes > Cellular Models. © 2017 The Authors. WIREs Systems Biology and Medicine published by Wiley Periodicals, Inc.

Laser illuminator and optical system for disk patterning

DOEpatents

Hackel, Lloyd A.; Dane, C. Brent; Dixit, Shamasundar N.; Everett, Mathew; Honig, John

2000-01-01

Magnetic recording media are textured over areas designated for contact in order to minimize friction with data transducing heads. In fabricating a hard disk, an aluminum nickel-phosphorous substrate is polished to a specular finish. A mechanical means is then used to roughen an annular area intended to be the head contact band. An optical and mechanical system allows thousands of spots to be generated with each laser pulse, allowing the textured pattern to be rapidly generated with a low repetition rate laser and an uncomplicated mechanical system. The system uses a low power laser, a beam expander, a specially designed phase plate, a prism to deflect the beam, a lens to transmit the diffraction pattern to the far field, a mechanical means to rotate the pattern and a trigger system to fire the laser when sections of the pattern are precisely aligned. The system generates an annular segment of the desired pattern with which the total pattern is generated by rotating the optical system about its optic axis, sensing the rotational position and firing the laser as the annular segment rotates into the next appropriate position. This marking system can be integrated into a disk sputtering system for manufacturing magnetic disks, allowing for a very streamlined manufacturing process.

The effect of ultrasound on enzymatic degumming process of rapeseed oil by the use of phospholipase A(1).

PubMed

Jiang, Xiaofei; Chang, Ming; Wang, Xiaosan; Jin, Qingzhe; Wang, Xingguo

2014-01-01

Comparative studies of enzymatic degumming process of rapeseed oil were carried out in mechanical-stirring and ultrasonic-assisted mechanical-stirring systems. The influences of enzyme dosage (10-50 mg/kg), pH (4.5-6), temperature (45-65 °C), water amount (1-3%), ultrasonic power (0.06-0.09 W/cm(3)) and reaction time were investigated subsequently. A suitable ultrasonic power of 0.07 W/cm(3) was determined to guarantee satisfactory degumming efficiency and enzyme activity. Compared to the mechanical-stirring system, optimum temperature of phospholipase A (PLA) in the ultrasonic-assisted mechanical-stirring system was about 5 °C higher, while the effects of pH on both of the two systems were quite similar. Less time and water were used in the ultrasonic-assisted mechanical-stirring system for enzymatic degumming. The study on the quality changes of degummed oils showed that ultrasound could accelerate the oxidation of edible oils due to the effect of cavitation, thus more attention should be paid on the oxidative stability in the further application. Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

Comparison of the iAssist Handheld Guidance System to Conventional Instruments for Mechanical Axis Restoration in Total Knee Arthroplasty.

PubMed

Kinney, Matthew C; Cidambi, Krishna R; Severns, Dustyn L; Gonzales, Francis B

2018-01-01

Recent advances in total knee arthroplasty (TKA) include an intelligent instrument system designed to provide intraoperative guidance to reduce mechanical alignment errors. Internal position-sensing technology is integrated into microelectronic pods that attach to cutting blocks. The purpose of this prospective, randomized study was to determine whether this iAssist system enables the surgeon to make more accurate bone resections and better restore the mechanical axis compared to conventional instruments in TKA. We randomized patients undergoing TKA into 2 groups. Group I (n = 25) underwent TKA assisted by the iAssist guidance system, group II (n = 25) underwent TKA using conventional instruments. Preoperative and postoperative mechanical axes were measured from full-length lower extremity radiographs to evaluate alignment. Additional surgical parameters were also assessed, including tourniquet time and blood loss. Patient demographics and preoperative mechanical axis alignments were similar between the groups. Postoperatively, 4.0% of patients had greater than 3° of tibial or femoral component mal-alignment in the guidance-assisted cohort, compared with 36.0% in the conventional group (P < .05). Additionally, group I showed significant improvement in variance seen in both the femoral mechanical axis (1.65° ± 0.17° vs 2.23° ± 0.33°, P < .005) and tibial mechanical axis (1.28° ± 0.13° vs 1.71° ± 0.24°, P < .005) compared to group II. There were no significant differences in tourniquet time (P = .86) or blood loss (P = .39) between groups. Use of the iAssist system in TKA results in an improved postoperative mechanical axis and decreased alignment variability compared to conventional instruments, without significantly increasing operative time. Copyright © 2017 Elsevier Inc. All rights reserved.

Evaluation of the propulsion control system of a planetary rover and design of a mast for an elevation scanning laser/multi-detector system

NASA Technical Reports Server (NTRS)

Knaub, D.; Yerazunis, S. W.

1978-01-01

Vertical wheel loads, wheel speeds, and torque relationships are considered in the design of a propulsion system capable of responding to steering, slope climbing, and irregular local terrains. The system developed is applied to the RPI Mars roving vehicle. The mechanical system required to implement the elevation laser scanning/multidetector principle was the design and construction of a mechanical system for implementing the elevation scanning/multidetector principle is also discussed.

Thermal management and mechanical structures for silicon detector systems

NASA Astrophysics Data System (ADS)

Viehhauser, G.

2015-09-01

Due to the size of current silicon tracking systems system aspects have become a major design driver. This article discusses requirements for the engineering of the mechanical structures and thermal management of such systems and reviews solutions developed to satisfy them. Modern materials and fabrication techniques have been instrumental in constructing these devices and will be discussed here. Finally, this paper will describe current and potential future developments in the engineering of silicon tracking systems which will shape the silicon tracking systems of the future.

[The immune system and the eye].

PubMed

Faber, Carsten; Nissen, Mogens Holst

2008-09-15

The special relationship between the eye and the immune system rests on a number of anatomical, physiological and immunological mechanisms. These mechanisms prevent the delicate structures of the eye from potentially damaging immunogenic inflammation while protecting against pathogens. Rather than inflammation, antigen induces a form of systemic and antigen-specific immunological tolerance. Owing to its systemic nature, this tolerance may be utilised to achieve successful treatment of immunological disorders.

LOX/GOX mechanical impact tester assessment

NASA Technical Reports Server (NTRS)

Bransford, J. W.; Bryan, C. J.; Frye, G. W.; Stohler, S. L.

1980-01-01

The performances of three existing high pressure oxygen mechanical impact test systems were tested at two different test sites. The systems from one test site were fabricated from the same design drawing, whereas the system tested at the other site was of different design. Energy delivered to the test sample for each test system was evaluated and compared. Results were compared to the reaction rates obtained.

Precision displacement reference system

DOEpatents

Bieg, Lothar F.; Dubois, Robert R.; Strother, Jerry D.

2000-02-22

A precision displacement reference system is described, which enables real time accountability over the applied displacement feedback system to precision machine tools, positioning mechanisms, motion devices, and related operations. As independent measurements of tool location is taken by a displacement feedback system, a rotating reference disk compares feedback counts with performed motion. These measurements are compared to characterize and analyze real time mechanical and control performance during operation.

Micro-Electro-Mechanical Systems (MEMS) Fabrication Course Projects Review for FY15

DTIC Science & Technology

2015-09-01

TECHNICAL DOCUMENT 3298 September 2015 Micro-Electro-Mechanical Systems (MEMS) Fabrication Course Projects Review for FY15 Paul D. Swanson...Naval Warfare Systems Center Pacific (SSC Pacific), San Diego, CA. SSC Pacific’s Naval Innovative Science and Engineering (NISE) Program provided...for Miniaturized Flow Cytometer o Howard Dyckman: 71730 Infrared Waveguides o Teresa Emery: 55360 Bistable MEMS systems for Energy

Development of a Wearable Assist Robot for Walk Rehabilitation After Knee Arthroplasty Surgery

NASA Astrophysics Data System (ADS)

Terada, H.; Zhu, Y.; Horiguchi, K.; Nakamura, M.; Takahashi, R.

In Japan, it is popular that the disease knee joints will be replaced to artificial joints by surgery. And we have to assist so many patients for walk rehabilitation. So, the wearable assist robot has been developed. This robot includes the knee motion assist mechanism and the hip joint support mechanism. Especially, the knee motion assist mechanism consists of a non-circular gear and grooved cams. This mechanism rotates and slides simultaneously, which has two degree-of-freedom. Also, the hip joint support mechanism consists of a hip brace and a ball-joint. This mechanism can avoid motion constraints which are the internal or external rotation and the adduction or abduction. Then, the control algorithm, which considers an assisting timing for the walk rehabilitation, has been proposed. A sensing system of a walk state for this control system uses a heel contacts sensor and knee and hip joint rotation angle sensors. Also, the prototype robot has been tested. And it is confirmed that the assisting system is useful.

Three-Dimensional Optical Coherence Tomography

NASA Technical Reports Server (NTRS)

Gutin, Mikhail; Wang, Xu-Ming; Gutin, Olga

2009-01-01

Three-dimensional (3D) optical coherence tomography (OCT) is an advanced method of noninvasive infrared imaging of tissues in depth. Heretofore, commercial OCT systems for 3D imaging have been designed principally for external ophthalmological examination. As explained below, such systems have been based on a one-dimensional OCT principle, and in the operation of such a system, 3D imaging is accomplished partly by means of a combination of electronic scanning along the optical (Z) axis and mechanical scanning along the two axes (X and Y) orthogonal to the optical axis. In 3D OCT, 3D imaging involves a form of electronic scanning (without mechanical scanning) along all three axes. Consequently, the need for mechanical adjustment is minimal and the mechanism used to position the OCT probe can be correspondingly more compact. A 3D OCT system also includes a probe of improved design and utilizes advanced signal- processing techniques. Improvements in performance over prior OCT systems include finer resolution, greater speed, and greater depth of field.

Thermalization and its mechanism for generic quantum isolated systems

NASA Astrophysics Data System (ADS)

Olshanii, Maxim; Dunjko, Vanja; Rigol, Marcos

2008-05-01

Time dynamics of isolated many-body quantum systems has long been an elusive subject, perhaps most urgently needed in the foundations of quantum statistical mechanics. In generic systems, one expects the nonequilibrium dynamics to lead to thermalization: a relaxation to states where the values of macroscopic quantities are stationary, universal with respect to widely differing initial conditions, and predictable through the time-tested recipe of statistical mechanics. The relaxation mechanism is not obvious, however; dynamical chaos cannot play the key role as it does in classical systems since quantum evolution is linear. Here we demonstrateootnotetextM. Rigol, V. Dunjko, and M. Olshanii, to appear in Nature (2008), using the results of an ab initio numerical experiment with 5 hard-core bosons moving in a 5x5 lattice, that in quantum systems thermalization happens not in course of time evolution but instead at the level of individual eigenstates, as first proposed by DeutschootnotetextJ. M. Deutsch, Phys.Rev. A 43, 2046 (1991) and SrednickiootnotetextM. Srednicki, Phys. Rev. E 50, 888 (1994).

Summary of the Orbiter mechanical systems

NASA Technical Reports Server (NTRS)

Kiker, J.; Hinson, K.

1979-01-01

Major mechanical systems of the Orbiter space vehicle are summarized with respect to general design details, manner of operation, expected performance, and, where applicable, unique features. A synopsis of data obtained during the five atmospheric flight tests of spacecraft OV-101 and status of the systems for the first orbital spacecraft STS-1 are presented.

Engine Performance (Section B: Fuel and Exhaust Systems). Auto Mechanics Curriculum Guide. Module 3. Instructor's Guide.

ERIC Educational Resources Information Center

Rains, Larry

This module is the third of nine modules in the competency-based Missouri Auto Mechanics Curriculum Guide. Six units cover: fuel supply systems; carburetion; carburetor service; gasoline engine electronic fuel injection; diesel fuel injection; and exhaust systems and turbochargers. Introductory materials include a competency profile and…

40 CFR 63.1363 - Standards for equipment leaks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... mechanical seal system that includes a barrier fluid system and meets the requirements specified in... dual mechanical seal system is: (A) Operated with the barrier fluid at a pressure that is at all times... paragraph (a)(2) of this section. (5) Lines and equipment not containing process fluids are not subject to...

Significance of a Recurring Function in Energy Transfer

ERIC Educational Resources Information Center

Mishra, Subodha

2017-01-01

The appearance of a unique function in the energy transfer from one system to the other in different physical situations such as electrical, mechanical, optical, and quantum mechanical processes is established in this work. Though the laws governing the energy transformation and its transfer from system to system are well known, here we notice a…

Brakes. Auto Mechanics Curriculum Guide. Module 6. Instructor's Guide.

ERIC Educational Resources Information Center

Allain, Robert

This module is the sixth of nine modules in the competency-based Missouri Auto Mechanics Curriculum Guide. Eight units cover: introduction to automotive brake systems; disc and drum brake system components and how they operate; properties of brake fluid and procedures for bleeding the brake system; diagnosing and determining needed repairs on…

Steering and Suspension Systems. Auto Mechanics Curriculum Guide. Module 5. Instructor's Guide.

ERIC Educational Resources Information Center

Rains, Larry

This module is the fifth of nine modules in the competency-based Missouri Auto Mechanics Curriculum Guide. Seventeen units cover: steering system design; diagnosing steering systems problems; inspecting and replacing steering linkage components; manual and power steering gear service; manual and power rack and pinion steering gear service; power…

Personal health record systems and their security protection.

PubMed

Win, Khin Than; Susilo, Willy; Mu, Yi

2006-08-01

The objective of this study is to analyze the security protection of personal health record systems. To achieve this we have investigated different personal health record systems, their security functions, and security issues. We have noted that current security mechanisms are not adequate and we have proposed some security mechanisms to tackle these problems.

Application of Small-Scale Systems: Evaluation of Alternatives

Treesearch

John Wilhoit; Robert Rummer

1999-01-01

Large-scale mechanized systems are not well-suited for harvesting smaller tracts of privately owned forest land. New alternative small-scale harvesting systems are needed which utilize mechanized felling, have a low capital investment requirement, are small in physical size, and are based primarily on adaptations of current harvesting technology. This paper presents...

Learning Activity Packets for Auto Mechanics II. Section B--Electrical Systems.

ERIC Educational Resources Information Center

Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

Six learning activity packets (LAPs) are provided for the instructional area of electrical systems in the auto mechanics II program. They accompany an instructor's guide available separately. The LAPs outline the study activities and performance tasks for these six units: (1) basic electrical theory, (2) battery service, (3) starting system, (4)…

Detection of mechanical injury on pickling cucumbers using near-infrared hyperspectral imaging

NASA Astrophysics Data System (ADS)

Ariana, D.; Lu, R.; Guyer, D.

2005-11-01

Automated detection of defects on freshly harvested pickling cucumbers will help the pickle industry provide higher quality pickle products and reduce potential economic losses. Research was conducted on using a hyperspectral imaging system for detecting defects on pickling cucumbers caused by mechanical stress. A near-infrared hyperspectral imaging system was used to capture both spatial and spectral information from cucumbers in the spectral region of 900 - 1700 nm. The system consisted of an imaging spectrograph attached to an InGaAs camera with line-light fiber bundles as an illumination source. Cucumber samples were subjected to two forms of mechanical loading, dropping and rolling, to simulate stress caused by mechanical harvesting. Hyperspectral images were acquired from the cucumbers over time periods of 0, 1, 2, 3, and 6 days after mechanical stress. Hyperspectral image processing methods, including principal component analysis and wavelength selection, were developed to separate normal and mechanically injured cucumbers. Results showed that reflectance from normal or non-bruised cucumbers was consistently higher than that from bruised cucumbers. The spectral region between 950 and 1350 nm was found to be most effective for bruise detection. The hyperspectral imaging system detected all mechanically injured cucumbers immediately after they were bruised. The overall detection accuracy was 97% within two hours of bruising and it was lower as time progressed. Lower detection accuracies for the prolonged times after bruising were attributed to the self- healing of the bruised tissue after mechanical injury. This research demonstrated that hyperspectral imaging is useful for detecting mechanical injury on pickling cucumbers.

EBSD characterization of twinning in cold-rolled CP-Ti

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, X., E-mail: csulixu@hotmail.com; Duan, Y.L., E-mail: 876270744@qq.com; Xu, G.F., E-mail: csuxgf66@csu.edu.cn

2013-10-15

This work presents the use of a mechanical testing system and the electron backscatter diffraction technique to study the mechanical properties and twinning systems of cold-rolled commercial purity titanium, respectively. The dependence of twinning on the matrix orientation is analyzed by the distribution map of Schmid factor. The results showed that the commercial purity titanium experienced strong strain hardening and had excellent formability during rolling. Both the (112{sup ¯}2)<112{sup ¯}3{sup ¯}> compressive twins and (101{sup ¯}2)<101{sup ¯}1{sup ¯}> tensile twins were dependent on the matrix orientation. The Schmid factor of a grain influenced the activation of a particular twinning system.more » The specific rolling deformation of commercial purity titanium controlled the number and species of twinning systems and further changed the mechanical properties. - Highlights: • CP-Ti experienced strain hardening and had excellent formability. • Twins were dependent on the matrix orientation. • Schmid factor of a grain influenced the activation of a twinning system. • Rolling deformation controlled twinning systems and mechanical properties.« less

An overview of neural function and feedback control in human communication.

PubMed

Hood, L J

1998-01-01

The speech and hearing mechanisms depend on accurate sensory information and intact feedback mechanisms to facilitate communication. This article provides a brief overview of some components of the nervous system important for human communication and some electrophysiological methods used to measure cortical function in humans. An overview of automatic control and feedback mechanisms in general and as they pertain to the speech motor system and control of the hearing periphery is also presented, along with a discussion of how the speech and auditory systems interact.

Nanoelectromechanical systems: Nanodevice motion at microwave frequencies

NASA Astrophysics Data System (ADS)

Henry Huang, Xue Ming; Zorman, Christian A.; Mehregany, Mehran; Roukes, Michael L.

2003-01-01

It has been almost forgotten that the first computers envisaged by Charles Babbage in the early 1800s were mechanical and not electronic, but the development of high-frequency nanoelectromechanical systems is now promising a range of new applications, including sensitive mechanical charge detectors and mechanical devices for high-frequency signal processing, biological imaging and quantum measurement. Here we describe the construction of nanodevices that will operate with fundamental frequencies in the previously inaccessible microwave range (greater than 1 gigahertz). This achievement represents a significant advance in the quest for extremely high-frequency nanoelectromechanical systems.

Dynamic processes in regulation and some implications for biofeedback and biobehavioral interventions.

PubMed

Lehrer, Paul; Eddie, David

2013-06-01

Systems theory has long been used in psychology, biology, and sociology. This paper applies newer methods of control systems modeling for assessing system stability in health and disease. Control systems can be characterized as open or closed systems with feedback loops. Feedback produces oscillatory activity, and the complexity of naturally occurring oscillatory patterns reflects the multiplicity of feedback mechanisms, such that many mechanisms operate simultaneously to control the system. Unstable systems, often associated with poor health, are characterized by absence of oscillation, random noise, or a very simple pattern of oscillation. This modeling approach can be applied to a diverse range of phenomena, including cardiovascular and brain activity, mood and thermal regulation, and social system stability. External system stressors such as disease, psychological stress, injury, or interpersonal conflict may perturb a system, yet simultaneously stimulate oscillatory processes and exercise control mechanisms. Resonance can occur in systems with negative feedback loops, causing high-amplitude oscillations at a single frequency. Resonance effects can be used to strengthen modulatory oscillations, but may obscure other information and control mechanisms, and weaken system stability. Positive as well as negative feedback loops are important for system function and stability. Examples are presented of oscillatory processes in heart rate variability, and regulation of autonomic, thermal, pancreatic and central nervous system processes, as well as in social/organizational systems such as marriages and business organizations. Resonance in negative feedback loops can help stimulate oscillations and exercise control reflexes, but also can deprive the system of important information. Empirical hypotheses derived from this approach are presented, including that moderate stress may enhance health and functioning.

[The system theory of aging: methodological principles, basic tenets and applications].

PubMed

Krut'ko, V N; Dontsov, V I; Zakhar'iashcheva, O V

2009-01-01

The paper deals with the system theory of aging constructed on the basis of present-day scientific methodology--the system approach. The fundamental cause for aging is discrete existence of individual life forms, i.e. living organisms which, from the thermodynamic point of view, are not completely open systems. The primary aging process (build-up of chaos and system disintegration of aging organism) obeys the second law of thermodynamics or the law of entropy increase in individual partly open systems. In living organisms the law is exhibited as synergy of four main aging mechanisms: system "pollution" of organism, loss of non-regenerative elements, accumulation of damages and deformations, generation of variability on all levels, and negative changes in regulation processes and consequent degradation of the organism systematic character. These are the general aging mechanisms; however, the regulatory mechanisms may be important equally for organism aging and search for ways to prolong active life.

Towards an Automated Development Methodology for Dependable Systems with Application to Sensor Networks

NASA Technical Reports Server (NTRS)

Hinchey, Michael G.; Rash, James L.; Rouff, Christopher A.

2005-01-01

A general-purpose method to mechanically transform system requirements into a probably equivalent model has yet to appeal: Such a method represents a necessary step toward high-dependability system engineering for numerous possible application domains, including sensor networks and autonomous systems. Currently available tools and methods that start with a formal model of a system and mechanically produce a probably equivalent implementation are valuable but not su8cient. The "gap" unfilled by such tools and methods is that their. formal models cannot be proven to be equivalent to the system requirements as originated by the customel: For the classes of systems whose behavior can be described as a finite (but significant) set of scenarios, we offer a method for mechanically transforming requirements (expressed in restricted natural language, or in other appropriate graphical notations) into a probably equivalent formal model that can be used as the basis for code generation and other transformations.

Control of mechanical systems with rolling constraints: Application to dynamic control of mobile robots

NASA Technical Reports Server (NTRS)

Sarkar, Nilanjan; Yun, Xiaoping; Kumar, Vijay

1994-01-01

There are many examples of mechanical systems that require rolling contacts between two or more rigid bodies. Rolling contacts engender nonholonomic constraints in an otherwise holonomic system. In this article, we develop a unified approach to the control of mechanical systems subject to both holonomic and nonholonomic constraints. We first present a state space realization of a constrained system. We then discuss the input-output linearization and zero dynamics of the system. This approach is applied to the dynamic control of mobile robots. Two types of control algorithms for mobile robots are investigated: trajectory tracking and path following. In each case, a smooth nonlinear feedback is obtained to achieve asymptotic input-output stability and Lagrange stability of the overall system. Simulation results are presented to demonstrate the effectiveness of the control algorithms and to compare the performane of trajectory-tracking and path-following algorithms.

Quality of protection evaluation of security mechanisms.

PubMed

Ksiezopolski, Bogdan; Zurek, Tomasz; Mokkas, Michail

2014-01-01

Recent research indicates that during the design of teleinformatic system the tradeoff between the systems performance and the system protection should be made. The traditional approach assumes that the best way is to apply the strongest possible security measures. Unfortunately, the overestimation of security measures can lead to the unreasonable increase of system load. This is especially important in multimedia systems where the performance has critical character. In many cases determination of the required level of protection and adjustment of some security measures to these requirements increase system efficiency. Such an approach is achieved by means of the quality of protection models where the security measures are evaluated according to their influence on the system security. In the paper, we propose a model for QoP evaluation of security mechanisms. Owing to this model, one can quantify the influence of particular security mechanisms on ensuring security attributes. The methodology of our model preparation is described and based on it the case study analysis is presented. We support our method by the tool where the models can be defined and QoP evaluation can be performed. Finally, we have modelled TLS cryptographic protocol and presented the QoP security mechanisms evaluation for the selected versions of this protocol.

Fool-proofing design and crisis management for customized intelligent physical fitness and healthcare system.

PubMed

Huang, Chung-Chi; Huang, Chung-Lin; Liu, Hsiao-Man

2015-01-01

In recent years, it is quite important to develop a customized system which can enhance physical fitness and health for people. And the system reliability is more important. In the paper, a fool-proofing design and crisis management for customized physical fitness and healthcare system is proposed. It is designed to prevent the failure of the various mechanisms of customized physical fitness and healthcare system, including records, surveillance, assessments, predictions, diagnosis, prescription, and scheduling. It is separated into (1) fool-proofing design module (2) crisis management module. The fool-proofing indexes are set to prevent the failure of the various mechanisms. The states of the various mechanisms are managed by the auto-checked fool-proofing indexes. If mistakes prevention was fail, we have to execute the crisis management for stopping harmful results. The crisis management will find the error level and response the solution by using fuzzy method. By the experiments, we can find the advantages of the fool-proofing design and crisis management for customized physical fitness and healthcare system. And it is effective to prevent the failure of the various mechanisms of intelligent customized physical fitness and healthcare system.

The mechanisms of neurotoxicity and the selective vulnerability of nervous system sites.

PubMed

Maurer, Laura L; Philbert, Martin A

2015-01-01

The spatial heterogeneity of the structure, function, and cellular composition of the nervous system confers extraordinary complexity and a multiplicity of mechanisms of chemical neurotoxicity. Because of its relatively high metabolic demands and functional dependence on postmitotic neurons, the nervous system is vulnerable to a variety of xenobiotics that affect essential homeostatic mechanisms that support function. Despite protection from the neuroglia and blood-brain barrier, the central nervous system is prone to attack from lipophilic toxicants and those that hijack endogenous transport, receptor, metabolic, and other biochemical systems. The inherent predilection of chemicals for highly conserved biochemical systems confers selective vulnerability of the nervous system to neurotoxicants. This chapter discusses selective vulnerability of the nervous system in the context of neuron-specific decrements (axonopathy, myelinopathy, disruption of neurotransmission), and the degree to which neuronal damage is facilitated or ameliorated by surrounding nonneural cells in both the central and peripheral nervous systems. © 2015 Elsevier B.V. All rights reserved.

Researcher Biographies

Science.gov Websites

interest: mechanical system design sensitivity analysis and optimization of linear and nonlinear structural systems, reliability analysis and reliability-based design optimization, computational methods in committee member, ISSMO; Associate Editor, Mechanics Based Design of Structures and Machines; Associate

Concept for Highly Mechanized Data Processing, Project 111.

DTIC Science & Technology

A concept is developed for a highly mechanized maintenance data processing system capable of deriving factors, influences, and correlations to raise...the level of logistics knowledge and lead to the design of a management-control system. (Author)

Unified hatch system

NASA Technical Reports Server (NTRS)

Hart, R. J.; Walkover, L. J.; Zosky, E. W.

1971-01-01

Special hatch sealing mechanism design increases safety, reliability, and convenience. Adaptations are possible for oceanographic and high-speed aircraft design, or for any system where quick-opening pressure hatch is required. In normal mode, hatching mechanism is manually operated from either side.

Methods And Systms For Analyzing The Degradation And Failure Of Mechanical Systems

DOEpatents

Jarrell, Donald B.; Sisk, Daniel R.; Hatley, Darrel D.; Kirihara, Leslie J.; Peters, Timothy J.

2005-02-08

Methods and systems for identifying, understanding, and predicting the degradation and failure of mechanical systems are disclosed. The methods include measuring and quantifying stressors that are responsible for the activation of degradation mechanisms in the machine component of interest. The intensity of the stressor may be correlated with the rate of physical degradation according to some determinable function such that a derivative relationship exists between the machine performance, degradation, and the underlying stressor. The derivative relationship may be used to make diagnostic and prognostic calculations concerning the performance and projected life of the machine. These calculations may be performed in real time to allow the machine operator to quickly adjust the operational parameters of the machinery in order to help minimize or eliminate the effects of the degradation mechanism, thereby prolonging the life of the machine. Various systems implementing the methods are also disclosed.

A space release/deployment system actuated by shape memory wires

NASA Astrophysics Data System (ADS)

Fragnito, Marino; Vetrella and, Sergio

2002-11-01

In this paper, the design of an innovative hold down/release and deployment device actuated by shape memory wires, to be used for the first time for the S MA RT microsatellite solar wings is shown. The release and deployment mechanisms are actuated by a Shape Memory wire (Nitinol), which allows a complete symmetrical and synchronous release, in a very short time, of the four wings in pairs. The hold down kinematic mechanism is preloaded to avoid vibration nonlinearities and unwanted deployment at launch. The deployment mechanism is a simple pulley system. The stiffness of the deployed panel-hinge system needs to be dimensioned in order to meet the on-orbit requirement for attitude control. One-way roller clutches are used to keep the panel at the desired angle during the mission. An ad hoc software has been developed to simulate both the release and deployment operations, coupling the SMA wire behavior with the system mechanics.

Model systems for life processes on Mars

NASA Technical Reports Server (NTRS)

Mitz, M. A.

1974-01-01

In the evolution of life forms nonphotosynthetic mechanisms are developed. The question remains whether a total life system could evolve which is not dependent upon photosynthesis. In trying to visualize life on other planets, the photosynthetic process has problems. On Mars, the high intensity of light at the surface is a concern and alternative mechanisms need to be defined and analyzed. In the UV search for alternate mechanisms, several different areas may be identified. These involve activated inorganic compounds in the atmosphere, such as the products of photodissociation of carbon dioxide and the organic material which may be created by natural phenomena. In addition, a life system based on the pressure of the atmospheric constituents, such as carbon dioxide, is a possibility. These considerations may be important for the understanding of evolutionary processes of life on another planet. Model systems which depend on these alternative mechanisms are defined and related to presently planned and future planetary missions.

A characteristic length scale causes anomalous size effects and boundary programmability in mechanical metamaterials

NASA Astrophysics Data System (ADS)

Coulais, Corentin; Kettenis, Chris; van Hecke, Martin

2018-01-01

The architecture of mechanical metamaterials is designed to harness geometry, nonlinearity and topology to obtain advanced functionalities such as shape morphing, programmability and one-way propagation. Although a purely geometric framework successfully captures the physics of small systems under idealized conditions, large systems or heterogeneous driving conditions remain essentially unexplored. Here we uncover strong anomalies in the mechanics of a broad class of metamaterials, such as auxetics, shape changers or topological insulators; a non-monotonic variation of their stiffness with system size, and the ability of textured boundaries to completely alter their properties. These striking features stem from the competition between rotation-based deformations--relevant for small systems--and ordinary elasticity, and are controlled by a characteristic length scale which is entirely tunable by the architectural details. Our study provides new vistas for designing, controlling and programming the mechanics of metamaterials.

Analysis and design of a mechanical system to use with the Ronchi and Fizeau tests

NASA Astrophysics Data System (ADS)

Galán-Martínez, Arturo D.; Santiago-Alvarado, Agustín.; González-García, Jorge; Cruz-Martínez, Víctor M.; Cordero-Dávila, Alberto; Granados-Agustin, Fermin S.; Robledo-Sánchez, Calos

2013-11-01

Nowadays, there is a demand for more efficient opto-mechanical mounts which allow for the implementation of robust optical arrays in a quick and simple fashion. That is to say, mounts are needed which facilitate alignment of the optical components in order to perform the desired movements of each component. Optical testing systems available in the market today are costly, heavy and sometimes require multiple kits depending on the dimensions of the optical components. In this paper, we present the design and analysis of a mechanical system with some interchangeable basic mounts which allow for the application of both Ronchi and Fizeau tests for the evaluation of concave reflective surfaces with a diameter of 2 to 10 cm. The mechanical system design is done using the methodology of product design process, while the analysis is performed using the commercial software SolidWorks.

Considerations of Alloy 617 Application in the Gen IV Nuclear Reactor Systems - Part I: Mechanical Property Challenges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Weiju

2010-01-01

Alloy 617 is currently considered as a leading candidate material for high temperature components in the Gen IV Nuclear Reactor Systems. Because of the unprecedented severe working conditions beyond its commercial service experience required by the Gen IV systems, the alloy faces various challenges in both mechanical and metallurgical properties. This paper, as Part I of the discussion, is focused on the challenges and issues in the mechanical properties of Alloy 617 for the intended nuclear application. Considerations are given in details in its mechanical property data scatter, low creep strength in the desired high temperature range, lack of longtermmore » creep curves, high loading rate dependency, and preponderant tertiary creep. Some research and development activities are suggested with discussions on their viability to satisfy the Gen IV Nuclear Reactor System needs in near future and in the long run.« less

Neuron-Glia Interactions and Nervous System Homeostasis

DTIC Science & Technology

1988-06-01

active neuron states, the mechanisms which glial cells and neurons use to modulate each others metabolic state and the chemical, electrical and... mechanisms by which axons/neurons and their glial cell investments communicate to actively regulate the ionic microenvironment of the nervous system and...of the glial cell in maintenance of the ionic homeostasis of the perineural environment during resting and active neuron states, the mechanisms which

Shape Memory Actuation and Release Devices.

DTIC Science & Technology

1996-10-01

shelf devices such as pyrotechnics, gas-discharge systems, paraffin wax actuators, and other electro-mechanical devices may not be able to meet...shelf devices such as pyrotechnics, gas-discharge systems, paraffin wax actuators, and other electro-mechanical devices may not be able to meet future...shard mounts. They do have wide utility as pin-pullers and single point release devices for a variety of spacecraft appendages. Parrafin based mechanisms

Research in nonlinear structural and solid mechanics

NASA Technical Reports Server (NTRS)

Mccomb, H. G., Jr. (Compiler); Noor, A. K. (Compiler)

1981-01-01

Recent and projected advances in applied mechanics, numerical analysis, computer hardware and engineering software, and their impact on modeling and solution techniques in nonlinear structural and solid mechanics are discussed. The fields covered are rapidly changing and are strongly impacted by current and projected advances in computer hardware. To foster effective development of the technology perceptions on computing systems and nonlinear analysis software systems are presented.

Cauldrons: An Abstraction for Concurrent Problems Solving. Revision.

DTIC Science & Technology

1986-09-01

iaCtio1ns are the cauldron, a mechanism for organizing inference into distinct reasoning contexts: the flmse. a way of mnodularly describing the components...reasoning systems. 1 . Main Points This paper develops three mechanisms for organizing large distributed reasoning systems: Cauldrons -- A chunk of...introduction.s ’Thc goal-node/frame mechanism supports a useful abstraction over the hare cauldrons implementation, providing a protocol for organizing

Experimental and computational investigation of Morse taper conometric system reliability for the definition of fixed connections between dental implants and prostheses.

PubMed

Bressan, Eriberto; Lops, Diego; Tomasi, Cristiano; Ricci, Sara; Stocchero, Michele; Carniel, Emanuele Luigi

2014-07-01

Nowadays, dental implantology is a reliable technique for treatment of partially and completely edentulous patients. The achievement of stable dentition is ensured by implant-supported fixed dental prostheses. Morse taper conometric system may provide fixed retention between implants and dental prostheses. The aim of this study was to investigate retentive performance and mechanical strength of a Morse taper conometric system used as implant-supported fixed dental prostheses retention. Experimental and finite element investigations were performed. Experimental tests were achieved on a specific abutment-coping system, accounting for both cemented and non-cemented situations. The results from the experimental activities were processed to identify the mechanical behavior of the coping-abutment interface. Finally, the achieved information was applied to develop reliable finite element models of different abutment-coping systems. The analyses were developed accounting for different geometrical conformations of the abutment-coping system, such as different taper angle. The results showed that activation process, occurred through a suitable insertion force, could provide retentive performances equal to a cemented system without compromising the mechanical functionality of the system. These findings suggest that Morse taper conometrical system can provide a fixed connection between implants and dental prostheses if proper insertion force is applied. Activation process does not compromise the mechanical functionality of the system. © IMechE 2014.

Study on the performance of the articulated mechanism of tracked all-terrain vehicle

NASA Astrophysics Data System (ADS)

Meng, Zhongliang; Zang, Hao

2018-04-01

Tracked all-terrain vehicle consists of two vehicle bodies featured by superior performance, the running system which can meet the all-terrain requirement, the unique steering system, power system and the vehicle body protection system. This paper focuses on the study of the five freely articulated steering system of crawler-type all-terrain engineering vehicle. The study on the dynamic characteristics of the articulated steering system can't do without the dynamic analysis of the whole vehicle. Therefore, it first studies the overall model of the tracked all-terrain vehicle, and then based on the critical states where the overall model is situated under different road conditions, mathematical models of the articulated mechanism are built under different operating conditions and also the load bearing condition of the articulated mechanism is deduced.

Practical homeostasis lighting control system using sensor agent robots for office space

NASA Astrophysics Data System (ADS)

Tokiwa, Momoko; Mita, Akira

2014-03-01

The comfortable space can be changed by season, age, physical condition and the like. However, the current systems are not able to resolve them absolutely. This research proposes the Homeostasis lighting control system based on the mechanism of biotic homeostasis for making the algorithms of apparatus control. Homeostasis are kept by the interaction of the three systems, endocrine system, immune system, and nervous system[1]. By the gradual reaction in the endocrine system, body's protective response in the immune system, and the electrical reaction in the nerve system, we can keep the environments against variable changes. The new lighting control system utilizes this mechanism. Firstly, we focused on legibility and comfort in the office space to construct the control model learning from the endocrine and immune systems. The mechanism of the endocrine system is used for ambient lights in the space is used considering circadian rhythm for comfort. For the legibility, the immune system is used to control considering devices near the human depending on the distance between the human. Simulations and the demonstration were conducted to show the feasibility. Finally, the nerve system was intruded to enhance the system.

[Construction of automatic elucidation platform for mechanism of traditional Chinese medicine].

PubMed

Zhang, Bai-xia; Luo, Si-jun; Yan, Jing; Gu, Hao; Luo, Ji; Zhang, Yan-ling; Tao, Ou; Wang, Yun

2015-10-01

Aim at the two problems in the field of traditional Chinese medicine (TCM) mechanism elucidation, one is the lack of detailed biological processes information, next is the low efficient in constructing network models, we constructed an auxiliary elucidation system for the TCM mechanism and realize the automatic establishment of biological network model. This study used the Entity Grammar Systems (EGS) as the theoretical framework, integrated the data of formulae, herbs, chemical components, targets of component, biological reactions, signaling pathways and disease related proteins, established the formal models, wrote the reasoning engine, constructed the auxiliary elucidation system for the TCM mechanism elucidation. The platform provides an automatic modeling method for biological network model of TCM mechanism. It would be benefit to perform the in-depth research on TCM theory of natures and combination and provides the scientific references for R&D of TCM.

Microfluidic strategies for understanding the mechanics of cells and cell-mimetic systems

PubMed Central

Dahl, Joanna B.; Lin, Jung-Ming G.; Muller, Susan J.; Kumar, Sanjay

2016-01-01

Microfluidic systems are attracting increasing interest for the high-throughput measurement of cellular biophysical properties and for the creation of engineered cellular microenvironments. Here we review recent applications of microfluidic technologies to the mechanics of living cells and synthetic cell-mimetic systems. We begin by discussing the use of microfluidic devices to dissect the mechanics of cellular mimics such as capsules and vesicles. We then explore applications to circulating cells, including erythrocytes and other normal blood cells, and rare populations with potential disease diagnostic value, such as circulating tumor cells. We conclude by discussing how microfluidic devices have been used to investigate the mechanics, chemotaxis, and invasive migration of adherent cells. In these ways, microfluidic technologies represent an increasingly important toolbox for investigating cellular mechanics and motility at high throughput and in a format that lends itself to clinical translation. PMID:26134738

Hydrogen generation systems and methods utilizing sodium silicide and sodium silica gel materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

Systems, devices, and methods combine thermally stable reactant materials and aqueous solutions to generate hydrogen and a non-toxic liquid by-product. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Springs and other pressurization mechanisms pressurize and deliver an aqueous solution to the reaction. A check valve and other pressure regulation mechanisms regulate the pressure of the aqueous solution delivered to the reactantmore » fuel material in the reactor based upon characteristics of the pressurization mechanisms and can regulate the pressure of the delivered aqueous solution as a steady decay associated with the pressurization force. The pressure regulation mechanism can also prevent hydrogen gas from deflecting the pressure regulation mechanism.« less

Hydrogen generation systems and methods utilizing sodium silicide and sodium silica gel materials

DOEpatents

Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael

2015-08-11

Systems, devices, and methods combine thermally stable reactant materials and aqueous solutions to generate hydrogen and a non-toxic liquid by-product. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Springs and other pressurization mechanisms pressurize and deliver an aqueous solution to the reaction. A check valve and other pressure regulation mechanisms regulate the pressure of the aqueous solution delivered to the reactant fuel material in the reactor based upon characteristics of the pressurization mechanisms and can regulate the pressure of the delivered aqueous solution as a steady decay associated with the pressurization force. The pressure regulation mechanism can also prevent hydrogen gas from deflecting the pressure regulation mechanism.

Osmotic regulation of gene action.

PubMed

Douzou, P

1994-03-01

Most reactions involved in gene translation systems are ionic-dependent and may be explained in electrostatic terms. However, a number of observations of equilibria and rate processes making up the overall reactions clearly indicate that there is still an enormous gap between the rough picture of the mechanism of ionic regulation and the detailed behavior of reactions at the molecular level that hold the key to specific mechanisms. The present paper deals with possible osmotic contributions arising from the gel state of gene systems that are complementary to, and interdependent of, electrostatic contributions. This treatment, although still oversimplified, explains many previous observations by relating them to a general osmotic mechanism and suggests experimental approaches to studying the mechanisms of gene regulation in organelle-free and intact systems.

Optimization and benchmarking of a perturbative Metropolis Monte Carlo quantum mechanics/molecular mechanics program

NASA Astrophysics Data System (ADS)

Feldt, Jonas; Miranda, Sebastião; Pratas, Frederico; Roma, Nuno; Tomás, Pedro; Mata, Ricardo A.

2017-12-01

In this work, we present an optimized perturbative quantum mechanics/molecular mechanics (QM/MM) method for use in Metropolis Monte Carlo simulations. The model adopted is particularly tailored for the simulation of molecular systems in solution but can be readily extended to other applications, such as catalysis in enzymatic environments. The electrostatic coupling between the QM and MM systems is simplified by applying perturbation theory to estimate the energy changes caused by a movement in the MM system. This approximation, together with the effective use of GPU acceleration, leads to a negligible added computational cost for the sampling of the environment. Benchmark calculations are carried out to evaluate the impact of the approximations applied and the overall computational performance.

A practical iterative PID tuning method for mechanical systems using parameter chart

NASA Astrophysics Data System (ADS)

Kang, M.; Cheong, J.; Do, H. M.; Son, Y.; Niculescu, S.-I.

2017-10-01

In this paper, we propose a method of iterative proportional-integral-derivative parameter tuning for mechanical systems that possibly possess hidden mechanical resonances, using a parameter chart which visualises the closed-loop characteristics in a 2D parameter space. We employ a hypothetical assumption that the considered mechanical systems have their upper limit of the derivative feedback gain, from which the feasible region in the parameter chart becomes fairly reduced and thus the gain selection can be extremely simplified. Then, a two-directional parameter search is carried out within the feasible region in order to find the best set of parameters. Experimental results show the validity of the assumption used and the proposed parameter tuning method.

An Educational Program of Mechatronics for Multidisciplinary Knowledge Acquisition

NASA Astrophysics Data System (ADS)

Watanuki, Keiichi; Kojima, Kazuyuki

Recently, as the technologies surrounding mechanical engineering have improved remarkably, the expectations for students who graduate from departments of mechanical engineering have increased. For example, in order to develop a mechatronics system, a student needs to integrate a wide variety of technologies, such as mechanical engineering, electrical and electronics engineering, and information technology. Therefore, from the perspective of educators, the current education system, which stresses expertizing each technology, should be replaced by an education system that stresses integrating multidisciplinary knowledge. In this paper, a trial education program for students of the department of mechanical engineering in our university, in which students are required to integrate multidisciplinary knowledge in order to develop a biologically-based robot, is described. Finally, the efficacy of the program is analyzed.

Optimization and benchmarking of a perturbative Metropolis Monte Carlo quantum mechanics/molecular mechanics program.

PubMed

Feldt, Jonas; Miranda, Sebastião; Pratas, Frederico; Roma, Nuno; Tomás, Pedro; Mata, Ricardo A

2017-12-28

In this work, we present an optimized perturbative quantum mechanics/molecular mechanics (QM/MM) method for use in Metropolis Monte Carlo simulations. The model adopted is particularly tailored for the simulation of molecular systems in solution but can be readily extended to other applications, such as catalysis in enzymatic environments. The electrostatic coupling between the QM and MM systems is simplified by applying perturbation theory to estimate the energy changes caused by a movement in the MM system. This approximation, together with the effective use of GPU acceleration, leads to a negligible added computational cost for the sampling of the environment. Benchmark calculations are carried out to evaluate the impact of the approximations applied and the overall computational performance.

Mechanical regulation of musculoskeletal system development.

PubMed

Felsenthal, Neta; Zelzer, Elazar

2017-12-01

During embryogenesis, the musculoskeletal system develops while containing within itself a force generator in the form of the musculature. This generator becomes functional relatively early in development, exerting an increasing mechanical load on neighboring tissues as development proceeds. A growing body of evidence indicates that such mechanical forces can be translated into signals that combine with the genetic program of organogenesis. This unique situation presents both a major challenge and an opportunity to the other tissues of the musculoskeletal system, namely bones, joints, tendons, ligaments and the tissues connecting them. Here, we summarize the involvement of muscle-induced mechanical forces in the development of various vertebrate musculoskeletal components and their integration into one functional unit. © 2017. Published by The Company of Biologists Ltd.

Mount mechanisms for the Saturn 5/Apollo mobile launcher at John F. Kennedy Space Center

NASA Technical Reports Server (NTRS)

Balke, H. A.

1975-01-01

A support system was designed to resist hurricane wind loads at the launch pad and to allow the supported structural frame to expand and contract freely under wide ranges of temperature. This system consists of six mount mechanisms devised to meet the previously stated requirements plus a load-carrying capacity for each of 3.2-million kilograms (7-million pounds) downward and 1.6-million kilograms (3.5-million pounds) upward. A similar but lighter system of six mount mechanisms was designed for use in the sheltered environment of the vehicle assembly building. Each requirement and design result is discussed, and each mount mechanism is defined by location and type with references to visual presentations.

Interfacing planar superconducting qubits with high overtone bulk acoustic phonons

NASA Astrophysics Data System (ADS)

Kervinen, Mikael; Rissanen, Ilkka; Sillanpää, Mika

2018-05-01

Mechanical resonators are a promising way for interfacing qubits in order to realize hybrid quantum systems that offer great possibilities for applications. Mechanical systems can have very long energy lifetimes, and they can be further interfaced to other systems. Moreover, integration of a mechanical oscillator with qubits creates a potential platform for the exploration of quantum physics in macroscopic mechanical degrees of freedom. The utilization of high overtone bulk acoustic resonators coupled to superconducting qubits is an intriguing platform towards these goals. These resonators exhibit a combination of high-frequency and high-quality factors. They can reach their quantum ground state at dilution refrigeration temperatures and they can be strongly coupled to superconducting qubits via their piezoelectric effect. In this paper, we demonstrate our system where bulk acoustic phonons of a high overtone resonator are coupled to a transmon qubit in a planar circuit architecture. We show that the bulk acoustic phonons are interacting with the qubit in a simple design architecture at the quantum level, representing further progress towards the quantum control of mechanical motion.

Making Sense of Bell's Theorem and Quantum Nonlocality

NASA Astrophysics Data System (ADS)

Boughn, Stephen

2017-05-01

Bell's theorem has fascinated physicists and philosophers since his 1964 paper, which was written in response to the 1935 paper of Einstein, Podolsky, and Rosen. Bell's theorem and its many extensions have led to the claim that quantum mechanics and by inference nature herself are nonlocal in the sense that a measurement on a system by an observer at one location has an immediate effect on a distant entangled system (one with which the original system has previously interacted). Einstein was repulsed by such "spooky action at a distance" and was led to question whether quantum mechanics could provide a complete description of physical reality. In this paper I argue that quantum mechanics does not require spooky action at a distance of any kind and yet it is entirely reasonable to question the assumption that quantum mechanics can provide a complete description of physical reality. The magic of entangled quantum states has little to do with entanglement and everything to do with superposition, a property of all quantum systems and a foundational tenet of quantum mechanics.

Cargo-Positioning System for Next-Generation Spacecraft

NASA Technical Reports Server (NTRS)

Holladay, Jon; Colton, Jonathan

2006-01-01

A report discusses a proposed system for mounting loaded pallets in the cargo bay of a next-generation space-shuttle-like spacecraft, such that the center of mass of the cargo would lie within a 1-in. (2.54-cm) cube that would also contain the center of mass of the spacecraft. The system would include (1) an algorithm for planning the locations of the pallets, given the geometric and weight properties of the pallets, and the geometric restrictions of the cargo bay; (2) quick-connect/quick-disconnect mounting mechanisms similar to those now used on air hoses; (3) other mounting mechanisms, comprising mostly spring-loaded pins, in a locking subsystem that would prevent shifting of the pallets under load; and (4) mechanisms for performing fine position adjustments to satisfy the center-of-mass requirement. The position- adjusting mechanisms would be motor-driven lead-screw mechanisms in groups of three - one for positioning each pin of the locking subsystem along each of three mutually perpendicular coordinate axes. The system also would include a triple-threaded screw that would provide compensation for thermal expansion or contraction of the spacecraft.

Inhaled nano- and microparticles for drug delivery

PubMed Central

El-Sherbiny, Ibrahim M.; El-Baz, Nancy M.; Yacoub, Magdi H.

2015-01-01

The 21st century has seen a paradigm shift to inhaled therapy, for both systemic and local drug delivery, due to the lung's favourable properties of a large surface area and high permeability. Pulmonary drug delivery possesses many advantages, including non-invasive route of administration, low metabolic activity, control environment for systemic absorption and avoids first bypass metabolism. However, because the lung is one of the major ports of entry, it has multiple clearance mechanisms, which prevent foreign particles from entering the body. Although these clearance mechanisms maintain the sterility of the lung, clearance mechanisms can also act as barriers to the therapeutic effectiveness of inhaled drugs. This effectiveness is also influenced by the deposition site and delivered dose. Particulate-based drug delivery systems have emerged as an innovative and promising alternative to conventional inhaled drugs to circumvent pulmonary clearance mechanisms and provide enhanced therapeutic efficiency and controlled drug release. The principle of multiple pulmonary clearance mechanisms is reviewed, including mucociliary, alveolar macrophages, absorptive, and metabolic degradation. This review also discusses the current approaches and formulations developed to achieve optimal pulmonary drug delivery systems. PMID:26779496

Bench-to-bedside review: Angiopoietin signalling in critical illness – a future target?

PubMed Central

van Meurs, Matijs; Kümpers, Philipp; Ligtenberg, Jack JM; Meertens, John HJM; Molema, Grietje; Zijlstra, Jan G

2009-01-01

Multiple organ dysfunction syndrome (MODS) occurs in response to major insults such as sepsis, severe haemorrhage, trauma, major surgery and pancreatitis. The mortality rate is high despite intensive supportive care. The pathophysiological mechanism underlying MODS are not entirely clear, although several have been proposed. Overwhelming inflammation, immunoparesis, occult oxygen debt and other mechanisms have been investigated, and – despite many unanswered questions – therapies targeting these mechanisms have been developed. Unfortunately, only a few interventions, usually those targeting multiple mechanisms at the same time, have appeared to be beneficial. We clearly need to understand better the mechanisms that underlie MODS. The endothelium certainly plays an active role in MODS. It functions at the intersection of several systems, including inflammation, coagulation, haemodynamics, fluid and electrolyte balance, and cell migration. An important regulator of these systems is the angiopoietin/Tie2 signalling system. In this review we describe this signalling system, giving special attention to what is known about it in critically ill patients and its potential as a target for therapy. PMID:19435476

Dynamic behavior of the mechanical systems from the structure of a hybrid automobile

NASA Astrophysics Data System (ADS)

Dinel, Popa; Irina, Tudor; Nicolae-Doru, Stănescu

2017-10-01

In introduction are presented solutions of planetary mechanisms that can be used in the construction of the hybrid automobiles where the thermal and electrical sources must be coupled. The systems have in their composition a planetary mechanism with two degrees of mobility at which are coupled a thermal engine, two revertible electrical machines, a gear transmission with four gears and a differential mechanism which transmits the motion at the driving wheels. For the study of the dynamical behavior, with numerical results, one designs such mechanisms, models the elements with solids in AutoCAD, and obtains the mechanical properties of the elements. Further on, we present and solve the equations of motion of a hybrid automotive for which one knows the dynamical parameters.

Development Status of Low-Shock Payload Separation Mechanism for H-IIA Launch Vehicle

NASA Astrophysics Data System (ADS)

Terashima, Keita; Kamita, Toru; Horie, Youichi; Kobayashi, Masakazu; Onikura, Hiroki

2013-09-01

This paper presents the design, analysis and test results of the low-shock payload separation mechanism for the H-IIA launch vehicle. The mechanism is based on a simple and reliable four-bar linkage, which makes the release speed of the marman clamp band tension lower than the current system.The adequacy of the principle for low-shock mechanism was evaluated by some simulations and results of fundamental tests. Then, we established the reliability design model of this mechanism, and the adequacy of this model was evaluated by elemental tests.Finally, we conducted the system separation tests using the payload adapter to which the mechanism was assembled, to confirm that the actual separation shock level satisfied our target.

A Recovery System for Unmanned Underwater Vehicles

DTIC Science & Technology

2017-09-28

300170 1 of 10 A RECOVERY SYSTEM FOR UNMANNED UNDERWATER VEHICLES STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may...6 of 10 forces cannot be easily predicted and can be strong enough to require a significantly larger handling system and significantly more...the sea state, the ship handling system , the capture mechanism and the design of the capture mechanism 400. [0024] The water jets 100 will increase

A fluid–structure interaction model to characterize bone cell stimulation in parallel-plate flow chamber systems

PubMed Central

Vaughan, T. J.; Haugh, M. G.; McNamara, L. M.

2013-01-01

Bone continuously adapts its internal structure to accommodate the functional demands of its mechanical environment and strain-induced flow of interstitial fluid is believed to be the primary mediator of mechanical stimuli to bone cells in vivo. In vitro investigations have shown that bone cells produce important biochemical signals in response to fluid flow applied using parallel-plate flow chamber (PPFC) systems. However, the exact mechanical stimulus experienced by the cells within these systems remains unclear. To fully understand this behaviour represents a most challenging multi-physics problem involving the interaction between deformable cellular structures and adjacent fluid flows. In this study, we use a fluid–structure interaction computational approach to investigate the nature of the mechanical stimulus being applied to a single osteoblast cell under fluid flow within a PPFC system. The analysis decouples the contribution of pressure and shear stress on cellular deformation and for the first time highlights that cell strain under flow is dominated by the pressure in the PPFC system rather than the applied shear stress. Furthermore, it was found that strains imparted on the cell membrane were relatively low whereas significant strain amplification occurred at the cell–substrate interface. These results suggest that strain transfer through focal attachments at the base of the cell are the primary mediators of mechanical signals to the cell under flow in a PPFC system. Such information is vital in order to correctly interpret biological responses of bone cells under in vitro stimulation and elucidate the mechanisms associated with mechanotransduction in vivo. PMID:23365189

Development and Validation of a Bioreactor System for Dynamic Loading and Mechanical Characterization of Whole Human Intervertebral Discs in Organ Culture

PubMed Central

Walter, BA; Illien-Junger, S; Nasser, P; Hecht, AC; Iatridis, JC

2014-01-01

Intervertebral disc (IVD) degeneration is a common cause of back pain, and attempts to develop therapies are frustrated by lack of model systems that mimic the human condition. Human IVD organ culture models can address this gap, yet current models are limited since vertebral endplates are removed to maintain cell viability, physiological loading is not applied, and mechanical behaviors are not measured. This study aimed to (i) establish a method for isolating human IVDs from autopsy with intact vertebral endplates, and (ii) develop and validate an organ culture loading system for human or bovine IVDs. Human IVDs with intact endplates were isolated from cadavers within 48 hours of death and cultured for up to 21 days. IVDs remained viable with ~80% cell viability in nucleus and annulus regions. A dynamic loading system was designed and built with the capacity to culture 9 bovine or 6 human IVDs simultaneously while applying simulated physiologic loads (maximum force: 4kN) and measuring IVD mechanical behaviors. The loading system accurately applied dynamic loading regimes (RMS error <2.5N and total harmonic distortion <2.45%), and precisely evaluated mechanical behavior of rubber and bovine IVDs. Bovine IVDs maintained their mechanical behavior and retained >85% viable cells throughout the 3 week culture period. This organ culture loading system can closely mimic physiological conditions and be used to investigate response of living human and bovine IVDs to mechanical and chemical challenges and to screen therapeutic repair techniques. PMID:24725441

Mechanical topological insulator in zero dimensions

NASA Astrophysics Data System (ADS)

Lera, Natalia; Alvarez, J. V.

2018-04-01

We study linear vibrational modes in finite isostatic Maxwell lattices, mechanical systems where the number of degrees of freedom matches the number of constraints. Recent progress in topological mechanics exploits the nontrivial topology of BDI class Hamiltonians in one dimenson and arising topological floppy modes at the edges. A finite frame, or zero-dimensional system, also exhibits a nonzero topological index according to the classification table. We construct mechanical insulating models in zero dimensions that complete the BDI classification in the available real space dimensions. We compute and interpret its nontrivial invariant Z2.