Revealing bending and force in a soft body through a plant root inspired approach

PubMed Central

Lucarotti, Chiara; Totaro, Massimo; Sadeghi, Ali; Mazzolai, Barbara; Beccai, Lucia

2015-01-01

An emerging challenge in soft robotics research is to reveal mechanical solicitations in a soft body. Nature provides amazing clues to develop unconventional components that are capable of compliant interactions with the environment and living beings, avoiding mechanical and algorithmic complexity of robotic design. We inspire from plant-root mechanoperception and develop a strategy able to reveal bending and applied force in a soft body with only two sensing elements of the same kind, and a null computational effort. The stretching processes that lead to opposite tissue deformations on the two sides of the root wall are emulated with two tactile sensing elements, made of soft and stretchable materials, which conform to reversible changes in the shape of the body they are built in and follow its deformations. Comparing the two sensory responses, we can discriminate the concave and the convex side of the bent body. Hence, we propose a new strategy to reveal in a soft body the maximum bending angle (or the maximum deflection) and the externally applied force according to the body's mechanical configuration. PMID:25739743

Historical Analysis of Population Reactions to Stimuli - Case Studies of Papua and Papua New Guinea

DTIC Science & Technology

2005-07-01

reduced by the modernisation and urbanisation of some elements of the population. However, there are still very traditional tribal and “untouched...colonialisation and introduction of Europeans to the island. Urbanisation (sense of nationalism) The movement of people from traditional village locations and...forces on the island during WWII and incorporates the colonisation and introduction of Europeans to the island. Urbanisation (sense of nationalism

Indirect Blood Pressure Measuring Device

NASA Technical Reports Server (NTRS)

Hum, L.; Cole, C. E.

1973-01-01

Design and performance of a blood pressure recording device for pediatric use are reported. A strain gage transducer with a copper-beryllium strip as force sensing element is used to monitor skin movements and to convert them into electrical signals proportional to those displacements. Experimental tests with this device in recording of force developed above the left femoral artery of a dog accurately produced a blood pressure curve.

Tri-axial tactile sensing element

NASA Astrophysics Data System (ADS)

Castellanos-Ramos, Julián.; Navas-González, Rafael; Vidal-Verdú, F.

2013-05-01

A 13 x 13 square millimetre tri-axial taxel is presented which is suitable for some medical applications, for instance in assistive robotics that involves contact with humans or in prosthetics. Finite Element Analysis is carried out to determine what structure is the best to obtain a uniform distribution of pressure on the sensing areas underneath the structure. This structure has been fabricated in plastic with a 3D printer and a commercial tactile sensor has been used to implement the sensing areas. A three axis linear motorized translation stage with a tri-axial precision force sensor is used to find the parameters of the linear regression model and characterize the proposed taxel. The results are analysed to see to what extent the goal has been reached in this specific implementation.

Miniaturized force/torque sensor for in vivo measurements of tissue characteristics.

PubMed

Hessinger, M; Pilic, T; Werthschutzky, R; Pott, P P

2016-08-01

This paper presents the development of a surgical instrument to measure interaction forces/torques with organic tissue during operation. The focus is on the design progress of the sensor element, consisting of a spoke wheel deformation element with a diameter of 12 mm and eight inhomogeneous doped piezoresistive silicon strain gauges on an integrated full-bridge assembly with an edge length of 500 μm. The silicon chips are contacted to flex-circuits via flip chip and bonded on the substrate with a single component adhesive. A signal processing board with an 18 bit serial A/D converter is integrated into the sensor. The design concept of the handheld surgical sensor device consists of an instrument coupling, the six-axis sensor, a wireless communication interface and battery. The nominal force of the sensing element is 10 N and the nominal torque is 1 N-m in all spatial directions. A first characterization of the force sensor results in a maximal systematic error of 4.92 % and random error of 1.13 %.

Magnetic field sensor based on the Ampere's force using dual-polarization DBR fiber laser

NASA Astrophysics Data System (ADS)

Yao, Shuang; Zhang, Yang; Guan, Baiou

2015-08-01

A novel magnetic field sensor using distributed Bragg reflector (DBR) fiber laser by Ampere's force effect is proposed and experimentally demonstrated. The key sensing element, that is the dual-polarization DBR fiber laser, is fixed on the middle part of two copper plates which carry the current. Ampere's force is applied onto the coppers due to an external magnetic field generated by a DC solenoid. Thus, the lateral force from the coppers is converted to a corresponding beat frequency signal shift produced by the DBR laser. The electric current sensing is also realized by the same configuration and same principle simultaneously in an intuitive manner. Good agreement between the theory calculation and the experimental results is obtained, which shows a good linearity. This sensor's sensitivity to the magnetic field and to the electric current finally reaches ~258.92 kHz/mT and ~1.08727 MHz/A, respectively.

Novel techniques for optical sensor using single core multi-layer structures for electric field detection

NASA Astrophysics Data System (ADS)

Ali, Amir R.; Kamel, Mohamed A.

2017-05-01

This paper studies the effect of the electrostriction force on the single optical dielectric core coated with multi-layers based on whispering gallery mode (WGM). The sensing element is a dielectric core made of polymeric material coated with multi-layers having different dielectric and mechanical properties. The external electric field deforming the sensing element causing shifts in its WGM spectrum. The multi-layer structures will enhance the body and the pressure forces acting on the core of the sensing element. Due to the gradient on the dielectric permittivity; pressure forces at the interface between every two layers will be created. Also, the gradient on Young's modulus will affect the overall stiffness of the optical sensor. In turn the sensitivity of the optical sensor to the electric field will be increased when the materials of each layer selected properly. A mathematical model is used to test the effect for that multi-layer structures. Two layering techniques are considered to increase the sensor's sensitivity; (i) Pressure force enhancement technique; and (ii) Young's modulus reduction technique. In the first technique, Young's modulus is kept constant for all layers, while the dielectric permittivity is varying. In this technique the results will be affected by the value dielectric permittivity of the outer medium surrounding the cavity. If the medium's dielectric permittivity is greater than that of the cavity, then the ascending ordered layers of the cavity will yield the highest sensitivity (the core will have the smallest dielectric permittivity) to the applied electric field and vice versa. In the second technique, Young's modulus is varying along the layers, while the dielectric permittivity has a certain constant value per layer. On the other hand, the descending order will enhance the sensitivity in the second technique. Overall, results show the multi-layer cavity based on these techniques will enhance the sensitivity compared to the typical polymeric optical sensor.

Design of a novel telerehabilitation system with a force-sensing mechanism.

PubMed

Zhang, Songyuan; Guo, Shuxiang; Gao, Baofeng; Hirata, Hideyuki; Ishihara, Hidenori

2015-05-19

Many stroke patients are expected to rehabilitate at home, which limits their access to proper rehabilitation equipment, treatment, or assessment by therapists. We have developed a novel telerehabilitation system that incorporates a human-upper-limb-like device and an exoskeleton device. The system is designed to provide the feeling of real therapist-patient contact via telerehabilitation. We applied the principle of a series elastic actuator to both the master and slave devices. On the master side, the therapist can operate the device in a rehabilitation center. When performing passive training, the master device can detect the therapist's motion while controlling the deflection of elastic elements to near-zero, and the patient can receive the motion via the exoskeleton device. When performing active training, the design of the force-sensing mechanism in the master device can detect the assisting force added by the therapist. The force-sensing mechanism also allows force detection with an angle sensor. Patients' safety is guaranteed by monitoring the motor's current from the exoskeleton device. To compensate for any possible time delay or data loss, a torque-limiter mechanism was also designed in the exoskeleton device for patients' safety. Finally, we successfully performed a system performance test for passive training with transmission control protocol/internet protocol communication.

Design of a Novel Telerehabilitation System with a Force-Sensing Mechanism

PubMed Central

Zhang, Songyuan; Guo, Shuxiang; Gao, Baofeng; Hirata, Hideyuki; Ishihara, Hidenori

2015-01-01

Many stroke patients are expected to rehabilitate at home, which limits their access to proper rehabilitation equipment, treatment, or assessment by therapists. We have developed a novel telerehabilitation system that incorporates a human-upper-limb-like device and an exoskeleton device. The system is designed to provide the feeling of real therapist–patient contact via telerehabilitation. We applied the principle of a series elastic actuator to both the master and slave devices. On the master side, the therapist can operate the device in a rehabilitation center. When performing passive training, the master device can detect the therapist’s motion while controlling the deflection of elastic elements to near-zero, and the patient can receive the motion via the exoskeleton device. When performing active training, the design of the force-sensing mechanism in the master device can detect the assisting force added by the therapist. The force-sensing mechanism also allows force detection with an angle sensor. Patients’ safety is guaranteed by monitoring the motor’s current from the exoskeleton device. To compensate for any possible time delay or data loss, a torque-limiter mechanism was also designed in the exoskeleton device for patients’ safety. Finally, we successfully performed a system performance test for passive training with transmission control protocol/internet protocol communication. PMID:25996511

Self-actuating reactor shutdown system

DOEpatents

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

1988-01-01

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

High speed magneto-resistive random access memory

NASA Technical Reports Server (NTRS)

Wu, Jiin-Chuan (Inventor); Stadler, Henry L. (Inventor); Katti, Romney R. (Inventor)

1992-01-01

A high speed read MRAM memory element is configured from a sandwich of magnetizable, ferromagnetic film surrounding a magneto-resistive film which may be ferromagnetic or not. One outer ferromagnetic film has a higher coercive force than the other and therefore remains magnetized in one sense while the other may be switched in sense by a switching magnetic field. The magneto-resistive film is therefore sensitive to the amplitude of the resultant field between the outer ferromagnetic films and may be constructed of a high resistivity, high magneto-resistive material capable of higher sensing currents. This permits higher read voltages and therefore faster read operations. Alternate embodiments with perpendicular anisotropy, and in-plane anisotropy are shown, including an embodiment which uses high permeability guides to direct the closing flux path through the magneto-resistive material. High density, high speed, radiation hard, memory matrices may be constructed from these memory elements.

Ultralow-Noise SiN Trampoline Resonators for Sensing and Optomechanics

NASA Astrophysics Data System (ADS)

Reinhardt, Christoph; Müller, Tina; Bourassa, Alexandre; Sankey, Jack C.

2016-04-01

In force sensing, optomechanics, and quantum motion experiments, it is typically advantageous to create lightweight, compliant mechanical elements with the lowest possible force noise. Here, we report the fabrication and characterization of high-aspect-ratio, nanogram-scale Si3 N4 "trampolines" having quality factors above 4 ×107 and ringdown times exceeding 5 min (mHz linewidth). These devices exhibit thermally limited force noise sensitivities below 20 aN /Hz1 /2 at room temperature, which is the lowest among solid-state mechanical sensors. We also characterize the suitability of these devices for high-finesse cavity readout and optomechanics applications, finding no evidence of surface or bulk optical losses from the processed nitride in a cavity achieving finesse 40,000. These parameters provide access to a single-photon cooperativity C0˜8 in the resolved-sideband limit, wherein a variety of outstanding optomechanics goals become feasible.

Sensing Performance Analysis on Quartz Tuning Fork-Probe at the High Order Vibration Mode for Multi-Frequency Scanning Probe Microscopy

PubMed Central

Gao, Fengli; Li, Xide

2018-01-01

Multi-frequency scanning near-field optical microscopy, based on a quartz tuning fork-probe (QTF-p) sensor using the first two orders of in-plane bending symmetrical vibration modes, has recently been developed. This method can simultaneously achieve positional feedback (based on the 1st in-plane mode called the low mode) and detect near-field optically induced forces (based on the 2nd in-plane mode called the high mode). Particularly, the high mode sensing performance of the QTF-p is an important issue for characterizing the tip-sample interactions and achieving higher resolution microscopic imaging but the related researches are insufficient. Here, we investigate the vibration performance of QTF-p at high mode based on the experiment and finite element method. The frequency spectrum characteristics are obtained by our homemade laser Doppler vibrometer system. The effects of the properties of the connecting glue layer and the probe features on the dynamic response of the QTF-p sensor at the high mode are investigated for optimization design. Finally, compared with the low mode, an obvious improvement of quality factor, of almost 50%, is obtained at the high mode. Meanwhile, the QTF-p sensor has a high force sensing sensitivity and a large sensing range at the high mode, indicating a broad application prospect for force sensing. PMID:29364847

Dual-loop model of the human controller

NASA Technical Reports Server (NTRS)

Hess, R. A.

1978-01-01

A dual-loop model of the human controller in single-axis compensatory tracking tasks is introduced. This model possesses an inner-loop closure that involves feeding back that portion of controlled element output rate that is due to control activity. A novel feature of the model is the explicit appearance of the human's internal representation of the manipulator-controlled element dynamics in the inner loop. The sensor inputs to the human controller are assumed to be system error and control force. The former can be sensed via visual, aural, or tactile displays, whereas the latter is assumed to be sensed in kinesthetic fashion. A set of general adaptive characteristics for the model is hypothesized, including a method for selecting simplified internal models of the manipulator-controlled element dynamics. It is demonstrated that the model can produce controller describing functions that closely approximate those measured in four laboratory tracking tasks in which the controlled element dynamics vary considerably in terms of ease of control. An empirically derived expression for the normalized injected error remnant spectrum is introduced.

Developing an Acoustic Sensing Yarn for Health Surveillance in a Military Setting.

PubMed

Hughes-Riley, Theodore; Dias, Tilak

2018-05-17

Overexposure to high levels of noise can cause permanent hearing disorders, which have a significant adverse effect on the quality of life of those affected. Injury due to noise can affect people in a variety of careers including construction workers, factory workers, and members of the armed forces. By monitoring the noise exposure of workers, overexposure can be avoided and suitable protective equipment can be provided. This work focused on the creation of a noise dosimeter suitable for use by members of the armed forces, where a discrete dosimeter was integrated into a textile helmet cover. In this way the sensing elements could be incorporated very close to the ears, providing a highly representative indication of the sound level entering the body, and also creating a device that would not interfere with military activities. This was achieved by utilising commercial microelectromechanical system microphones integrated within the fibres of yarn to create an acoustic sensing yarn. The acoustic sensing yarns were fully characterised over a range of relevant sound levels and frequencies at each stage in the yarn production process. The yarns were ultimately integrated into a knitted helmet cover to create a functional acoustic sensing helmet cover prototype.

Developing an Acoustic Sensing Yarn for Health Surveillance in a Military Setting

PubMed Central

Dias, Tilak

2018-01-01

Overexposure to high levels of noise can cause permanent hearing disorders, which have a significant adverse effect on the quality of life of those affected. Injury due to noise can affect people in a variety of careers including construction workers, factory workers, and members of the armed forces. By monitoring the noise exposure of workers, overexposure can be avoided and suitable protective equipment can be provided. This work focused on the creation of a noise dosimeter suitable for use by members of the armed forces, where a discrete dosimeter was integrated into a textile helmet cover. In this way the sensing elements could be incorporated very close to the ears, providing a highly representative indication of the sound level entering the body, and also creating a device that would not interfere with military activities. This was achieved by utilising commercial microelectromechanical system microphones integrated within the fibres of yarn to create an acoustic sensing yarn. The acoustic sensing yarns were fully characterised over a range of relevant sound levels and frequencies at each stage in the yarn production process. The yarns were ultimately integrated into a knitted helmet cover to create a functional acoustic sensing helmet cover prototype. PMID:29772756

Self-adjusting magnetic bearing systems

DOEpatents

Post, Richard F.

1998-01-01

A self-adjusting magnetic bearing automatically adjusts the parameters of an axially unstable magnetic bearing such that its force balance is maintained near the point of metastable equilibrium. Complete stabilization can be obtained with the application of weak restoring forces either from a mechanical bearing (running at near-zero load, thus with reduced wear) or from the action of residual eddy currents in a snubber bearing. In one embodiment, a torque is generated by the approach of a slotted pole to a conducting plate. The torque actuates an assembly which varies the position of a magnetic shunt to change the force exerted by the bearing. Another embodiment achieves axial stabilization by sensing vertical displacements in a suspended bearing element, and using this information in an electrical servo system. In a third embodiment, as a rotating eddy current exciter approaches a stationary bearing, it heats a thermostat which actuates an assembly to weaken the attractive force between the two bearing elements. An improved version of an electromechanical battery utilizing the designs of the various embodiments is described.

Self-adjusting magnetic bearing systems

DOEpatents

Post, R.F.

1998-07-21

A self-adjusting magnetic bearing automatically adjusts the parameters of an axially unstable magnetic bearing such that its force balance is maintained near the point of metastable equilibrium. Complete stabilization can be obtained with the application of weak restoring forces either from a mechanical bearing (running at near-zero load, thus with reduced wear) or from the action of residual eddy currents in a snubber bearing. In one embodiment, a torque is generated by the approach of a slotted pole to a conducting plate. The torque actuates an assembly which varies the position of a magnetic shunt to change the force exerted by the bearing. Another embodiment achieves axial stabilization by sensing vertical displacements in a suspended bearing element, and using this information in an electrical servo system. In a third embodiment, as a rotating eddy current exciter approaches a stationary bearing, it heats a thermostat which actuates an assembly to weaken the attractive force between the two bearing elements. An improved version of an electromechanical battery utilizing the designs of the various embodiments is described. 7 figs.

3D capacitive tactile sensor using DRIE micromachining

NASA Astrophysics Data System (ADS)

Chuang, Chiehtang; Chen, Rongshun

2005-07-01

This paper presents a three dimensional micro capacitive tactile sensor that can detect normal and shear forces which is fabricated using deep reactive ion etching (DRIE) bulk silicon micromachining. The tactile sensor consists of a force transmission plate, a symmetric suspension system, and comb electrodes. The sensing character is based on the changes of capacitance between coplanar sense electrodes. High sensitivity is achieved by using the high aspect ratio interdigital electrodes with narrow comb gaps and large overlap areas. The symmetric suspension mechanism of this sensor can easily solve the coupling problem of measurement and increase the stability of the structure. In this paper, the sensor structure is designed, the capacitance variation of the proposed device is theoretically analyzed, and the finite element analysis of mechanical behavior of the structures is performed.

A Global Framework for Monitoring Phenological Responses to Climate Change

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

White, Michael A; Hoffman, Forrest M; Hargrove, William Walter

2005-01-01

Remote sensing of vegetation phenology is an important method with which to monitor terrestrial responses to climate change, but most approaches include signals from multiple forcings, such as mixed phenological signals from multiple biomes, urbanization, political changes, shifts in agricultural practices, and disturbances. Consequently, it is difficult to extract a clear signal from the usually assumed forcing: climate change. Here, using global 8 km 1982 to 1999 Normalized Difference Vegetation Index (NDVI) data and an eight-element monthly climatology, we identified pixels whose wavelet power spectrum was consistently dominated by annual cycles and then created phenologically and climatically self-similar clusters, whichmore » we term phenoregions. We then ranked and screened each phenoregion as a function of landcover homogeneity and consistency, evidence of human impacts, and political diversity. Remaining phenoregions represented areas with a minimized probability of non-climatic forcings and form elemental units for long-term phenological monitoring.« less

Bioinspired active whisker sensor for robotic vibrissal tactile sensing

NASA Astrophysics Data System (ADS)

Ju, Feng; Ling, Shih-Fu

2014-12-01

A whisker transducer (WT) inspired by rat’s vibrissal tactile perception is proposed based on a transduction matrix model characterizing the electro-mechanical transduction process in both forward and backward directions. It is capable of acting as an actuator to sweep the whisker and simultaneously as a sensor to sense the force, motion, and mechanical impedance at whisker tip. Its validity is confirmed by numerical simulation using a finite element model. A prototype is then fabricated and its transduction matrix is determined by parameter identification. The calibrated WT can accurately sense mechanical impedance which is directly related to stiffness, mass and damping. Subsequent vibrissal tactile sensing of sandpaper texture reveals that the real part of mechanical impedance sensed by WT is correlated with sandpaper roughness. Texture discrimination is successfully achieved by inputting the real part to a k-means clustering algorithm. The mechanical impedance sensing ability as well as other features of the WT such as simultaneous-actuation-and-sensing makes it a good solution to robotic tactile sensing.

A Fabry-Perot Interferometry Based MRI-Compatible Miniature Uniaxial Force Sensor for Percutaneous Needle Placement

PubMed Central

Shang, Weijian; Su, Hao; Li, Gang; Furlong, Cosme; Fischer, Gregory S.

2014-01-01

Robot-assisted surgical procedures, taking advantage of the high soft tissue contrast and real-time imaging of magnetic resonance imaging (MRI), are developing rapidly. However, it is crucial to maintain tactile force feedback in MRI-guided needle-based procedures. This paper presents a Fabry-Perot interference (FPI) based system of an MRI-compatible fiber optic sensor which has been integrated into a piezoelectrically actuated robot for prostate cancer biopsy and brachytherapy in 3T MRI scanner. The opto-electronic sensing system design was minimized to fit inside an MRI-compatible robot controller enclosure. A flexure mechanism was designed that integrates the FPI sensor fiber for measuring needle insertion force, and finite element analysis was performed for optimizing the correct force-deformation relationship. The compact, low-cost FPI sensing system was integrated into the robot and calibration was conducted. The root mean square (RMS) error of the calibration among the range of 0–10 Newton was 0.318 Newton comparing to the theoretical model which has been proven sufficient for robot control and teleoperation. PMID:25126153

Mechano-adaptation of the stem cell nucleus.

PubMed

Heo, Su-Jin; Cosgrove, Brian D; Dai, Eric N; Mauck, Robert L

2018-01-01

Exogenous mechanical forces are transmitted through the cell and to the nucleus, initiating mechanotransductive signaling cascades with profound effects on cellular function and stem cell fate. A growing body of evidence has shown that the force sensing and force-responsive elements of the nucleus adapt to these mechanotransductive events, tuning their response to future mechanical input. The mechanisms underlying this "mechano-adaptation" are only just beginning to be elucidated, and it remains poorly understood how these components act and adapt in tandem to drive stem cell differentiation. Here, we review the evidence on how the stem cell nucleus responds and adapts to physical forces, and provide a perspective on how this mechano-adaptation may function to drive and enforce stem cell differentiation.

Mechano-adaptation of the stem cell nucleus

PubMed Central

Heo, Su-Jin; Cosgrove, Brian D.; Dai, Eric N.; Mauck, Robert L.

2018-01-01

ABSTRACT Exogenous mechanical forces are transmitted through the cell and to the nucleus, initiating mechanotransductive signaling cascades with profound effects on cellular function and stem cell fate. A growing body of evidence has shown that the force sensing and force-responsive elements of the nucleus adapt to these mechanotransductive events, tuning their response to future mechanical input. The mechanisms underlying this “mechano-adaptation” are only just beginning to be elucidated, and it remains poorly understood how these components act and adapt in tandem to drive stem cell differentiation. Here, we review the evidence on how the stem cell nucleus responds and adapts to physical forces, and provide a perspective on how this mechano-adaptation may function to drive and enforce stem cell differentiation. PMID:29099288

Tooth eruption results from bone remodelling driven by bite forces sensed by soft tissue dental follicles: a finite element analysis.

PubMed

Sarrafpour, Babak; Swain, Michael; Li, Qing; Zoellner, Hans

2013-01-01

Intermittent tongue, lip and cheek forces influence precise tooth position, so we here examine the possibility that tissue remodelling driven by functional bite-force-induced jaw-strain accounts for tooth eruption. Notably, although a separate true 'eruptive force' is widely assumed, there is little direct evidence for such a force. We constructed a three dimensional finite element model from axial computerized tomography of an 8 year old child mandible containing 12 erupted and 8 unerupted teeth. Tissues modelled included: cortical bone, cancellous bone, soft tissue dental follicle, periodontal ligament, enamel, dentine, pulp and articular cartilage. Strain and hydrostatic stress during incisive and unilateral molar bite force were modelled, with force applied via medial and lateral pterygoid, temporalis, masseter and digastric muscles. Strain was maximal in the soft tissue follicle as opposed to surrounding bone, consistent with follicle as an effective mechanosensor. Initial numerical analysis of dental follicle soft tissue overlying crowns and beneath the roots of unerupted teeth was of volume and hydrostatic stress. To numerically evaluate biological significance of differing hydrostatic stress levels normalized for variable finite element volume, 'biological response units' in Nmm were defined and calculated by multiplication of hydrostatic stress and volume for each finite element. Graphical representations revealed similar overall responses for individual teeth regardless if incisive or right molar bite force was studied. There was general compression in the soft tissues over crowns of most unerupted teeth, and general tension in the soft tissues beneath roots. Not conforming to this pattern were the unerupted second molars, which do not erupt at this developmental stage. Data support a new hypothesis for tooth eruption, in which the follicular soft tissues detect bite-force-induced bone-strain, and direct bone remodelling at the inner surface of the surrounding bony crypt, with the effect of enabling tooth eruption into the mouth.

Modeling of Lithium Niobate (LiNbO3) and Aluminum Nitride (AlN) Nanowires Using Comsol Multiphysics Software: The Case of Pressure Sensor

NASA Astrophysics Data System (ADS)

Ahmad, A. A.; Alsaad, A.; Al-Bataineh, Q. M.; Al-Naafa, M. A.

2018-02-01

In this study, Lithium niobate (LiNbO3) and Aluminum nitride (AlN) nanostructures were designed and investigated using the COMSOL Multiphysics software for pressure sensing applications. The Finite Element Method (FEM) was used for solving the differential equations with various parameters such as size, length, force, etc. The variation of the total maximum displacement as a function of applied force for various NWs lengths and the variation of the voltage as a function of applied force were plotted and discussed. AlN nanowires exhibit a better piezoelectric response than LiNbO3 nanowires do.

Tooth Eruption Results from Bone Remodelling Driven by Bite Forces Sensed by Soft Tissue Dental Follicles: A Finite Element Analysis

PubMed Central

Sarrafpour, Babak; Swain, Michael; Li, Qing; Zoellner, Hans

2013-01-01

Intermittent tongue, lip and cheek forces influence precise tooth position, so we here examine the possibility that tissue remodelling driven by functional bite-force-induced jaw-strain accounts for tooth eruption. Notably, although a separate true ‘eruptive force’ is widely assumed, there is little direct evidence for such a force. We constructed a three dimensional finite element model from axial computerized tomography of an 8 year old child mandible containing 12 erupted and 8 unerupted teeth. Tissues modelled included: cortical bone, cancellous bone, soft tissue dental follicle, periodontal ligament, enamel, dentine, pulp and articular cartilage. Strain and hydrostatic stress during incisive and unilateral molar bite force were modelled, with force applied via medial and lateral pterygoid, temporalis, masseter and digastric muscles. Strain was maximal in the soft tissue follicle as opposed to surrounding bone, consistent with follicle as an effective mechanosensor. Initial numerical analysis of dental follicle soft tissue overlying crowns and beneath the roots of unerupted teeth was of volume and hydrostatic stress. To numerically evaluate biological significance of differing hydrostatic stress levels normalized for variable finite element volume, ‘biological response units’ in Nmm were defined and calculated by multiplication of hydrostatic stress and volume for each finite element. Graphical representations revealed similar overall responses for individual teeth regardless if incisive or right molar bite force was studied. There was general compression in the soft tissues over crowns of most unerupted teeth, and general tension in the soft tissues beneath roots. Not conforming to this pattern were the unerupted second molars, which do not erupt at this developmental stage. Data support a new hypothesis for tooth eruption, in which the follicular soft tissues detect bite-force-induced bone-strain, and direct bone remodelling at the inner surface of the surrounding bony crypt, with the effect of enabling tooth eruption into the mouth. PMID:23554928

A Magnetically Suspended Wheel for a Miniature Gyro Made Using Planar Fabrication Technologies

NASA Technical Reports Server (NTRS)

Dauwalter, Charles R.

1996-01-01

The technical feasibility of a magnetically suspended rotating wheel for miniature gyro applications was investigated under a NASA SBIR contract. A concept for a configuration for a system of compact, lightweight magnetic actuators capable of generating the necessary suspension forces and fabrication using millimachining planar fabrication technologies was developed. Both capacitive and electromagnetic position sensing concepts were developed for implementing a closed loop control system for supporting the wheel. A finite difference technique, implemented in a spreadsheet environment, for analyzing the force characteristics of the actuator was used and the results verified with Finite Element Analysis.

Research on new dynamic force calibration system

NASA Astrophysics Data System (ADS)

Zhang, Li

2008-06-01

Sinusoidal force calibration method based on electrodynamic shaker and interferometric system was studied several years before at Physikalisch-Technische Bundesanstalt (PTB). In that system a load mass are screwed on the top of force transducer, the sinusoidal forces realized by accelerated load masses are traceable to acceleration and mass according to the force definition F(t) = ma(t), where m is the total mass acting on the sensing element of the force transducer and a is the time and spatial-dependent acceleration of the mass, which is directly measured by a laser interferometer. This paper will introduce a new dynamic force calibration system developed at Changcheng Institute of Metrology and Measurement (CIMM). It uses electrodynamic shakers to generate dynamic force in the range from 1N to 20kN, and heterodyne laser interferometers are used for acceleration measurement. A new air bearing system is developed to increase the performance of shakers and an active vibration isolator is used to reduce enviromental disturbance to the interferometric system.

Tactile sensor of hardness recognition based on magnetic anomaly detection

NASA Astrophysics Data System (ADS)

Xue, Lingyun; Zhang, Dongfang; Chen, Qingguang; Rao, Huanle; Xu, Ping

2018-03-01

Hardness, as one kind of tactile sensing, plays an important role in the field of intelligent robot application such as gripping, agricultural harvesting, prosthetic hand and so on. Recently, with the rapid development of magnetic field sensing technology with high performance, a number of magnetic sensors have been developed for intelligent application. The tunnel Magnetoresistance(TMR) based on magnetoresistance principal works as the sensitive element to detect the magnetic field and it has proven its excellent ability of weak magnetic detection. In the paper, a new method based on magnetic anomaly detection was proposed to detect the hardness in the tactile way. The sensor is composed of elastic body, ferrous probe, TMR element, permanent magnet. When the elastic body embedded with ferrous probe touches the object under the certain size of force, deformation of elastic body will produce. Correspondingly, the ferrous probe will be forced to displace and the background magnetic field will be distorted. The distorted magnetic field was detected by TMR elements and the output signal at different time can be sampled. The slope of magnetic signal with the sampling time is different for object with different hardness. The result indicated that the magnetic anomaly sensor can recognize the hardness rapidly within 150ms after the tactile moment. The hardness sensor based on magnetic anomaly detection principal proposed in the paper has the advantages of simple structure, low cost, rapid response and it has shown great application potential in the field of intelligent robot.

Optical sensing elements for nitrogen dioxide (NO.sub.2) gas detection, a sol-gel method for making the sensing elements and fiber optic sensors incorporating nitrogen dioxide gas optical sensing elements

DOEpatents

Mechery, Shelly John [Mississippi State, MS; Singh, Jagdish P [Starkville, MS

2007-07-03

A sensing element, a method of making a sensing element, and a fiber optic sensor incorporating the sensing element are described. The sensor can be used for the quantitative detection of NO.sub.2 in a mixture of gases. The sensing element can be made by incorporating a diazotizing reagent which reacts with nitrous ions to produce a diazo compound and a coupling reagent which couples with the diazo compound to produce an azo dye into a sol and allowing the sol to form an optically transparent gel. The sensing element changes color in the presence of NO.sub.2 gas. The temporal response of the absorption spectrum at various NO.sub.2 concentrations has also been recorded and analyzed. Sensors having different design configurations are described. The sensing element can detect NO.sub.2 gas at levels of parts per billion.

Force sensing of multiple-DOF cable-driven instruments for minimally invasive robotic surgery.

PubMed

He, Chao; Wang, Shuxin; Sang, Hongqiang; Li, Jinhua; Zhang, Linan

2014-09-01

Force sensing for robotic surgery is limited by the size of the instrument, friction and sterilization requirements. This paper presents a force-sensing instrument to avoid these restrictions. Operating forces were calculated according to cable tension. Mathematical models of the force-sensing system were established. A force-sensing instrument was designed and fabricated. A signal collection and processing system was constructed. The presented approach can avoid the constraints of space limits, sterilization requirements and friction introduced by the transmission parts behind the instrument wrist. Test results showed that the developed instrument has a 0.03 N signal noise, a 0.05 N drift, a 0.04 N resolution and a maximum error of 0.4 N. The validation experiment indicated that the operating and grasping forces can be effectively sensed. The developed force-sensing system can be used in minimally invasive robotic surgery to construct a force-feedback system. Copyright © 2013 John Wiley & Sons, Ltd.

Concurrent use of magnetic bearings for rotor support and force sensing for the nondestructive evaluation of manufacturing processes

NASA Astrophysics Data System (ADS)

Kasarda, Mary; Imlach, Joseph; Balaji, P. A.; Marshall, Jeremy T.

2000-06-01

Active magnetic bearings are a proven technology in turbomachinery applications and they offer considerable promise for improving the performance of manufacturing processes. The Active Magnetic Bearing (AMB) is a feedback mechanism that supports a spinning shaft by levitating it in a magnetic field. AMBs have significantly higher surface speed capability than rolling element bearings and they eliminate the potential for product contamination by eliminating the requirement for bearing lubrication. In addition, one of the most promising capabilities for manufacturing applications is the ability of the AMB to act concurrently as both a support bearing and non-invasive force sensor. The feedback nature of the AMB allows for its use as a load cell to continuously measure shaft forces necessary for levitation based on information about the magnetic flux density in the air gaps. This measurement capability may be exploited to improve the process control of such products as textile fibers and photographic films where changes in shaft loads may indicate changes in product quality. This paper discusses the operation of AMBs and their potential benefits in manufacturing equipment along with results from research addressing accurate AMB force sensing performance in field applications. Specifically, results from the development of enhanced AMB measurement algorithms to better account for magnetic fringing and leakage effects to improve the accuracy of this technique are presented. Results from the development of a new on-line calibration procedure for robust in-situ calibration of AMBs in a field application such as a manufacturing plant scenario are also presented including results of Magnetic Finite Element Analysis (MFEA) verification of the procedure.

Bolt Shear Force Sensor

DTIC Science & Technology

2015-03-12

submarine and ship systems required to survive the effects of mechanical shock must consider not only the system and foundation to which the system...See FIG. 1). In the figure, a Bragg grating sensor 1 is inserted and held by epoxy 2 in a mechanical fastener 10. Optical fiber 3 connects the...circumferential) strains. The sensing elements 120 are fixedly bonded to the vertical section 103 using conventional adhesives such as epoxies or

Smart structure with elastomeric contact surface for prosthetic fingertip sensitivity development

NASA Astrophysics Data System (ADS)

Gu, Chunxin; Liu, Weiting; Yu, Ping; Cheng, Xiaoying; Fu, Xin

2017-09-01

Current flexible/compliant tactile sensors suffer from low sensitivity and high hysteresis introduced by the essential viscosity characteristic of soft material, either used as compliant sensing element or as flexible coverage. To overcome these disadvantages, this paper focuses on developing a tactile sensor with a smart hybrid structure to obtain comprehensive properties in terms of size, compliance, robustness and pressure sensing ability so as to meet the requirements of limited space applications such as prosthetic fingertips. Employing micro-fabricated tiny silicon-based pressure die as the sensing element, it is easy to have both small size and good mechanical performance. To protect it from potential damage and maintain the compliant surface, a rigid base and a soft layer form a sealed chamber and encapsulate the fixed die together with fluid. The fluid serves as highly efficient pressure propagation media of mechanical stimulus from the compliant skin to the pressure die without any hazard impacting the vulnerable connecting wires. To understand the pressure transmission mechanism, a simplified and concise analytic model of a spring system is proposed. Using easy fabrication technologies, a prototype of a 3 × 3 sensor array with total dimensions of 14 mm × 14 mm × 6.5 mm was developed. Based on the quasi-linear relationship between fluid volume and pressure, finite element modeling was developed to analyze the chamber deformation and pressure output of the sensor cell. Experimental tests of the sensor prototype were implemented. The results showed that the sensor cell had good sensing performance with sensitivity of 19.9 mV N-1, linearity of 0.998, repeatability error of 3.41%, and hysteresis error of 3.34%. The force sensing range was from 5 mN to 1.6 N.

System implications of large radiometric array antennas

NASA Technical Reports Server (NTRS)

Levis, C. A.; Lin, H. C.

1976-01-01

Current radiometric earth and atmospheric sensing systems in the centimeter wavelength range generally employ a directive antenna connected through a single terminal pair to a Dicke receiver. It is shown that this approach does not lend itself to systems with greatly increased spatial resolution. Signal to noise considerations relating to antenna efficiency force the introduction of active elements at the subarray level; thus, if Dicke switching is to be used, it must be distributed throughout the system. Some possible approaches are suggested. The introduction of active elements at the subarray level is found to ease the design constraints on time delay elements, necessary for bandwidth, and on multiple beam generation, required in order to achieve sufficient integration time with high resolution.

Near-wall similarity in a pressure-driven three-dimensional turbulent boundary layer

NASA Technical Reports Server (NTRS)

Pierce, F. J.; Mcallister, J. E.

1980-01-01

Mean velocity, measured wall pressure and wall shear stress fields were made in a three dimensional pressure-driven turbulent boundary layer created by a cylinder with trailing edge placed normal to a flat plate floor. The direct force wall shear stress measurements were made with floating element direct force sensing shear meter that responded to both the magnitude and direction of the local wall shear stress. The ability of 10 near wall similarity models to describe the near wall velocity field for the measured flow under a wide range of skewing conditions and a variety of pressure gradient and wall shear vector orientations was used.

A Sub-Millimetric 3-DOF Force Sensing Instrument with Integrated Fiber Bragg Grating for Retinal Microsurgery

PubMed Central

He, Xingchi; Handa, James; Gehlbach, Peter; Taylor, Russell; Iordachita, Iulian

2013-01-01

Vitreoretinal surgery requires very fine motor control to perform precise manipulation of the delicate tissue in the interior of the eye. Besides physiological hand tremor, fatigue, poor kinesthetic feedback, and patient movement, the absence of force sensing is one of the main technical challenges. Previous two degrees of freedom (DOF) force sensing instruments have demonstrated robust force measuring performance. The main design challenge is to incorporate high sensitivity axial force sensing. This paper reports the development of a sub-millimetric 3-DOF force sensing pick instrument based on fiber Bragg grating (FBG) sensors. The configuration of the four FBG sensors is arranged to maximize the decoupling between axial and transverse force sensing. A super-elastic nitinol flexure is designed to achieve high axial force sensitivity. An automated calibration system was developed for repeatability testing, calibration, and validation. Experimental results demonstrate a FBG sensor repeatability of 1.3 pm. The linear model for calculating the transverse forces provides an accurate global estimate. While the linear model for axial force is only locally accurate within a conical region with a 30° vertex angle, a second-order polynomial model can provide a useful global estimate for axial force. Combining the linear model for transverse forces and nonlinear model for axial force, the 3-DOF force sensing instrument can provide sub-millinewton resolution for axial force and a quarter millinewton for transverse forces. Validation with random samples show the force sensor can provide consistent and accurate measurement of three dimensional forces. PMID:24108455

Development of a Piezoelectric Vacuum Sensing Component for a Wide Pressure Range

PubMed Central

Wang, Bing-Yu; Hsieh, Fan-Chun; Lin, Che-Yu; Chen, Shao-En; Chen, Fong-Zhi; Wu, Chia-Che

2014-01-01

In this study, we develop a clamped–clamped beam-type piezoelectric vacuum pressure sensing element. The clamped–clamped piezoelectric beam is composed of a PZT layer and a copper substrate. A pair of electrodes is set near each end. An input voltage is applied to a pair of electrodes to vibrate the piezoelectric beam, and the output voltage is measured at the other pair. Because the viscous forces on the piezoelectric beam vary at different air pressures, the vibration of the beam depends on the vacuum pressure. The developed pressure sensor can sense a wide range of pressure, from 6.5 × 10−6 to 760 Torr. The experimental results showed that the output voltage is inversely proportional to the gas damping ratio, and thus, the vacuum pressure was estimated from the output voltage. PMID:25421736

Metal foil method for noncontact measurement of lateral vibrations of a nonmetallic cylinder by a solenoid

NASA Astrophysics Data System (ADS)

Han, Soon Woo; Bang, Young Bong; Kim, Yoon Young

2006-10-01

This investigation shows that if a solenoid encircles a metal foil loop wound around a nonmetallic cylinder vibrating laterally, an electromotive force is induced in the solenoid. The induction is possible only when the foil loop is complete and an antisymmetric magnetic field is applied to the foil. In this work, stationary permanent magnets were used. Because the solenoid is the sensing element, no physical contact between the element and a test specimen is required. The effects of the metal foil thickness and width on the measurement sensitivity were studied and vibration modal testing of an acryl cylinder was performed.

Remote Sensing and Mass Migration Policy Development

DTIC Science & Technology

2012-10-01

ELEMENT NUMBER 6. AUTHOR (S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Air War...solely those of the author and do not necessarily represent the views of Air University, the United States Air Force, the Department of Defense, or...date, more than 100 African water basin authorities , universities and other organizations have become involved in TIGER projects across the

The Robonaut 2 Hand - Designed to do Work with Tools

NASA Technical Reports Server (NTRS)

Bridgwater, L. B.; Ihrke, C. A.; Diftler, M. A.; Abdallah, M. E.; Radford, N. A.; Rogers, J. M.; Yayathi, S.; Askew, R. S.; Linn, D. M.

2011-01-01

The second generation Robonaut hand has many advantages over its predecessor. This mechatronic device is more dexterous and has improved force control and sensing giving it the capability to grasp and actuate a wider range of tools. It can achieve higher peak forces at higher speeds than the original. Developed as part of a partnership between General Motors and NASA, the hand is designed to more closely approximate a human hand. Having a more anthropomorphic design allows the hand to attain a larger set of useful grasps for working with human interfaces. Key to the hand s improved performance is the use of lower friction drive elements and a redistribution of components from the hand to the forearm, permitting more sensing in the fingers and palm where it is most important. The following describes the design, mechanical/electrical integration, and control features of the hand. Lessons learned during the development and initial operations along with planned refinements to make it more effective are presented.

A Force-Sensing System on Legs for Biomimetic Hexapod Robots Interacting with Unstructured Terrain

PubMed Central

Wu, Rui; Li, Changle; Zang, Xizhe; Zhang, Xuehe; Jin, Hongzhe; Zhao, Jie

2017-01-01

The tiger beetle can maintain its stability by controlling the interaction force between its legs and an unstructured terrain while it runs. The biomimetic hexapod robot mimics a tiger beetle, and a comprehensive force sensing system combined with certain algorithms can provide force information that can help the robot understand the unstructured terrain that it interacts with. This study introduces a complicated leg force sensing system for a hexapod robot that is the same for all six legs. First, the layout and configuration of sensing system are designed according to the structure and sizes of legs. Second, the joint toque sensors, 3-DOF foot-end force sensor and force information processing module are designed, and the force sensor performance parameters are tested by simulations and experiments. Moreover, a force sensing system is implemented within the robot control architecture. Finally, the experimental evaluation of the leg force sensor system on the hexapod robot is discussed and the performance of the leg force sensor system is verified. PMID:28654003

A dual-loop model of the human controller in single-axis tracking tasks

NASA Technical Reports Server (NTRS)

Hess, R. A.

1977-01-01

A dual loop model of the human controller in single axis compensatory tracking tasks is introduced. This model possesses an inner-loop closure which involves feeding back that portion of the controlled element output rate which is due to control activity. The sensory inputs to the human controller are assumed to be system error and control force. The former is assumed to be sensed via visual, aural, or tactile displays while the latter is assumed to be sensed in kinesthetic fashion. A nonlinear form of the model is briefly discussed. This model is then linearized and parameterized. A set of general adaptive characteristics for the parameterized model is hypothesized. These characteristics describe the manner in which the parameters in the linearized model will vary with such things as display quality. It is demonstrated that the parameterized model can produce controller describing functions which closely approximate those measured in laboratory tracking tasks for a wide variety of controlled elements.

Remote Sensing and Mass Migration Policy Development

DTIC Science & Technology

2011-02-16

PROGRAM ELEMENT NUMBER 6. AUTHOR (S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Air War... author and do not reflect the official policy or position of the US government or the Department of Defense. In accordance with Air Force Instruction... authorities , universities and other organizations have become involved in TIGER projects across the continent.”42 The Horn of Africa, an arid to semi-arid

Au sensitized ZnO nanorods for enhanced liquefied petroleum gas sensing properties

NASA Astrophysics Data System (ADS)

Nakate, U. T.; Bulakhe, R. N.; Lokhande, C. D.; Kale, S. N.

2016-05-01

The zinc oxide (ZnO) nanorods have grown on glass substrate by spray pyrolysis deposition (SPD) method using zinc acetate solution. The phase formation, surface morphology and elemental composition of ZnO films have been investigated using X-ray diffraction, field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and energy dispersive X-ray (EDX) techniques. The liquefied petroleum gas (LPG) sensing response was remarkably improved by sensitization of gold (Au) surface noble metal on ZnO nanorods film. Maximum LPG response of 21% was observed for 1040 ppm of LPG, for pure ZnO nanorods sample. After Au sensitization on ZnO nanorods film sample, the LPG response greatly improved up to 48% at operating temperature 623 K. The improved LPG response is attributed Au sensitization with spill-over mechanism. Proposed model for LPG sensing mechanism discussed.

Generation of mechanical oscillation applicable to vibratory rate gyroscopes

NASA Technical Reports Server (NTRS)

Lemkin, Mark A. (Inventor); Juneau, Thor N. (Inventor); Clark, William A. (Inventor); Roessig, Allen W. (Inventor)

2001-01-01

To achieve a drive-axis oscillation with improved frequency and amplitude stability, additional feedback loops are used to adjust force-feedback loop parameters. An amplitude-control loop measures oscillation amplitude, compares this value to the desired level, and adjusts damping of the mechanical sense-element to grow or shrink oscillation amplitude as appropriate. A frequency-tuning loop measures the oscillation frequency, compares this value with a highly stable reference, and adjusts the gain in the force-feedback loop to keep the drive-axis oscillation frequency at the reference value. The combined topology simultaneously controls both amplitude and frequency. Advantages of the combined topology include improved stability, fast oscillation start-up, low power consumption, and excellent shock rejection.

Rigid two-axis MEMS force plate for measuring cellular traction force

NASA Astrophysics Data System (ADS)

Takahashi, Hidetoshi; Jung, Uijin G.; Kan, Tetsuo; Tsukagoshi, Takuya; Matsumoto, Kiyoshi; Shimoyama, Isao

2016-10-01

Cellular traction force is one of the important factors for understanding cell behaviors, such as spreading, migration and differentiation. Cells are known to change their behavior according to the mechanical stiffness of the environment. However, the measurement of cell traction forces on a rigid environment has remained difficult. This paper reports a micro-electromechanical systems (MEMS) force plate that provides a cellular traction force measurement on a rigid substrate. Both the high force sensitivity and high stiffness of the substrate were obtained using piezoresistive sensing elements. The proposed force plate consists of a 70 µm  ×  15 µm  ×  5 µm base as the substrate for cultivating a bovine aortic smooth muscle cell, and the supporting beams with piezoresistors on the sidewall and the surface were used to measure the forces in both the horizontal and vertical directions. The spring constant and force resolution of the fabricated force plate in the horizontal direction were 0.2 N m-1 and less than 0.05 µN, respectively. The cell traction force was measured, and the traction force increased by approximately 1 µN over 30 min. These results demonstrate that the proposed force plate is applicable as an effective traction force measurement.

Design, analysis, and fabrication of a piezoelectric force plate

NASA Astrophysics Data System (ADS)

Hoummadi, Elias; Safaei, Mohsen; Anton, Steven R.

2017-04-01

Force plates are used to detect static and dynamic reaction forces due to presence of stationary or moving objects as well as the location of applied forces. The application of force plates in various biomechanical fields, such as gait analysis, has been widely suggested and investigated in the past. Several sensor technologies like piezoelectrics, capacitance gauges, and piezoresistive sensors are utilized to develop force plates with special characteristics. Among the technologies employed in force plate designs, piezoelectrics present the ability of providing a self-powered sensory system. Recently, it has been suggested to implement piezoelectric transducers as sensors in the tibial bearing of total knee replacement (TKR) implants in order to transform the knee bearing into a force plate with the ability to detect force and contact point location for in vivo knee load analysis. Considering this application, a simplified design of a force plate instrumented with six piezoelectric transducers is presented in this study. The force plate is modeled using a finite element (FE) model to investigate the sensing performance of the system. In order to validate the simulation, a prototype force plate is fabricated and tested under the same loading condition applied on the FE model. The results are presented in terms of measured location and amplitude of applied force measured by the piezoelectric transducers. For the FE simulation, the deviation of the measured location of the applied force from the actual location is obtained as 0.62 mm in the x-direction and 0.13 mm in the y-direction, and the error in the amplitude of the measured force is 0.03% of the applied force. On the other hand, the deviation in the measured location of the force from the experimental test is 0.53 mm in the x-direction and 0.1 mm in the y-direction, while the error in force is 3.6% of the applied force. The small quantities of error in both sensed location and amplitude of applied force obtained from the FE simulation and experimental test results demonstrates the potential of the proposed design to be utilized as the sensor in the knee bearing of TKR implants.

Method for fabricating a microscale anemometer

NASA Technical Reports Server (NTRS)

Liu, Chang (Inventor); Chen, Jack (Inventor)

2008-01-01

Method for fabricating a microscale anemometer on a substrate. A sacrificial layer is formed on the substrate, and a metal thin film is patterned to form a sensing element. At least one support for the sensing element is patterned. The sacrificial layer is removed, and the sensing element is lifted away from the substrate by raising the supports, thus creating a clearance between the sensing element and the substrate to allow fluid flow between the sensing element and the substrate. The supports are raised preferably by use of a magnetic field applied to magnetic material patterned on the supports.

Fibre Bragg grating sensing and finite element analysis of the biomechanics of the mandible

NASA Astrophysics Data System (ADS)

Silva, J. C. C.; Ramos, A.; Carvalho, L.; Nogueira, R. N.; Ballu, A.; Mesnard, M.; Pinto, J. L.; Kalinowski, Hypolito J.; Simoes, J. A.

2005-05-01

This paper describes the application of fibre Bragg grating (FBG) sensors to measure strains at the outer surface of a mandible. The strains were correlated to identical ones obtained with a numerical finite element model. For this purpose, a synthetic mandible was used and 4 Bragg sensors were glued to the mandible. Strain patterns were assessed for different load configurations which included the forces of the masseter and temporal muscles and occlusion loads on different tooth (incisor, canine and molar). Overall the strains obtained using different measuring methods were identical, namely for the case of symmetric loading. When loading was non-symmetric, strain differences were observed at one sensor.

Principle, design and validation of a power-generated magnetorheological energy absorber with velocity self-sensing capability

NASA Astrophysics Data System (ADS)

Bai, Xian-Xu; Zhong, Wei-Min; Zou, Qi; Zhu, An-Ding; Sun, Jun

2018-07-01

Based on the structural design concept of ‘functional integration’, this paper proposes the principle of a power-generated magnetorheological energy absorber with velocity self-sensing capability (PGMREA), which realizes the integration of controllable damping mechanism and mechanical energy-electrical energy conversion mechanism in structure profile and multiple functions in function profile, including controllable damping, power generation and velocity self-sensing. The controllable damping mechanism consists of an annular gap and a ball screw. The annular gap fulfilled with MR fluid that operates in pure shear mode under controllable electromagnetic field. The rotational damping torque generated from the controllable damping mechanism is translated to a linear damping force via the ball screw. The mechanical energy-electrical energy conversion mechanism is realized by the ball screw and a generator composed of a permanent magnet rotor and a generator stator. The ball screw based mechanical energy-electrical energy conversion mechanism converts the mechanical energy of excitations to electrical energy for storage or directly to power the controllable damping mechanism of the PGMREA. The velocity self-sensing capability of the PGMREA is achieved via signal processing using the mechanical energy-electrical energy conversion information. Based on the principle of the proposed PGMREA, the mathematical model of the PGMREA is established, including the damping force, generated power and self-sensing velocity. The electromagnetic circuit of the PGMREA is simulated and verified via a finite element analysis software ANSYS. The developed PGMREA prototype is experimentally tested on a servo-hydraulic testing system. The model-based predicted results and the experimental results are compared and analyzed.

Research on the Sensing Performance of the Tuning Fork-Probe as a Micro Interaction Sensor

PubMed Central

Gao, Fengli; Li, Xide

2015-01-01

The shear force position system has been widely used in scanning near-field optical microscopy (SNOM) and recently extended into the force sensing area. The dynamic properties of a tuning fork (TF), the core component of this system, directly determine the sensing performance of the shear positioning system. Here, we combine experimental results and finite element method (FEM) analysis to investigate the dynamic behavior of the TF probe assembled structure (TF-probe). Results from experiments under varying atmospheric pressures illustrate that the oscillation amplitude of the TF-probe is linearly related to the quality factor, suggesting that decreasing the pressure will dramatically increase the quality factor. The results from FEM analysis reveal the influences of various parameters on the resonant performance of the TF-probe. We compared numerical results of the frequency spectrum with the experimental data collected by our recently developed laser Doppler vibrometer system. Then, we investigated the parameters affecting spatial resolution of the SNOM and the dynamic response of the TF-probe under longitudinal and transverse interactions. It is found that the interactions in transverse direction is much more sensitive than that in the longitudinal direction. Finally, the TF-probe was used to measure the friction coefficient of a silica–silica interface. PMID:26404310

A comparison of FE beam and continuum elements for typical nitinol stent geometries

NASA Astrophysics Data System (ADS)

Ballew, Wesley; Seelecke, Stefan

2009-03-01

With interest in improved efficiency and a more complete description of the SMA material, this paper compares finite element (FE) simulations of typical stent geometries using two different constitutive models and two different element types. Typically, continuum elements are used for the simulation of stents, for example the commercial FE software ANSYS offers a continuum element based on Auricchio's SMA model. Almost every stent geometry, however, is made up of long and slender components and can be modeled more efficiently, in the computational sense, with beam elements. Using the ANSYS user programmable material feature, we implement the free energy based SMA model developed by Mueller and Seelecke into the ANSYS beam element 188. Convergence behavior for both, beam and continuum formulations, is studied in terms of element and layer number, respectively. This is systematically illustrated first for the case of a straight cantilever beam under end loading, and subsequently for a section of a z-bend wire, a typical stent sub-geometry. It is shown that the computation times for the beam element are reduced to only one third of those of the continuum element, while both formulations display a comparable force/displacement response.

Construction of 2,4,6-Trinitrotoluene Biosensors with Novel Sensing Elements from Escherichia coli K-12 MG1655.

PubMed

Tan, Junjie; Kan, Naipeng; Wang, Wei; Ling, Jingyi; Qu, Guolong; Jin, Jing; Shao, Yu; Liu, Gang; Chen, Huipeng

2015-06-01

Detection of 2,4,6-trinitrotoluene (TNT) has been extensively studied since it is a common explosive filling for landmines, posing significant threats to the environment and human safety. The rapid advances in synthetic biology give new hope to detect such toxic and hazardous compounds in a more sensitive and safe way. Biosensor construction anticipates finding sensing elements able to detect TNT. As TNT can induce some physiological responses in E. coli, it may be useful to define the sensing elements from E. coli to detect TNT. An E. coli MG1655 genomic promoter library containing nearly 5,400 elements was constructed. Five elements, yadG, yqgC, aspC, recE, and topA, displayed high sensing specificity to TNT and its indicator compounds 1,3-DNB and 2,4-DNT. Based on this, a whole cell biosensor was constructed using E. coli, in which green fluorescent protein was positioned downstream of the five sensing elements via genetic fusion. The threshold value, detection time, EC200 value, and other aspects of five sensing elements were determined and the minimum responding concentration to TNT was 4.75 mg/L. According to the synthetic biology, the five sensing elements enriched the reservoir of TNT-sensing elements, and provided a more applicable toolkit to be applied in genetic routes and live systems of biosensors in future.

Apparatus for providing vibrotactile sensory substitution of force feedback

NASA Technical Reports Server (NTRS)

Massimino, Michael J. (Inventor); Sheridan, Thomas B. (Inventor); Patrick, Nicholas J. M. (Inventor)

1997-01-01

A feedback apparatus for an operator to control an effector that is remote from the operator to interact with a remote environment has a local input device to be manipulated by the operator. Sensors in the effector's environment are capable of sensing the amplitude of forces arising between the effector and its environment, the direction of application of such forces, or both amplitude and direction. A feedback signal corresponding to such a component of the force, is generated and transmitted to the environment of the operator. The signal is transduced into a vibrotactile sensory substitution signal to which the operator is sensitive. Vibration producing apparatus present the vibrotactile signal to the operator. The full range of the force amplitude may be represented by a single, mechanical vibrator. Vibrotactile display elements can be located on the operator's limbs, such as on the hand, fingers, arms, legs, feet, etc. The location of the application of the force may also be specified by the location of a vibrotactile display on the operator's body. Alternatively, the location may be specified by the frequency of a vibrotactile signal.

Scalable, MEMS-enabled, vibrational tactile actuators for high resolution tactile displays

NASA Astrophysics Data System (ADS)

Xie, Xin; Zaitsev, Yuri; Velásquez-García, Luis Fernando; Teller, Seth J.; Livermore, Carol

2014-12-01

The design, fabrication, and characterization of a new type of tactile display for people with blindness or low vision is reported. Each tactile element comprises a piezoelectric extensional actuator that vibrates in plane, with a microfabricated scissor mechanism to convert the in-plane actuations into robust, higher-amplitude, out-of-plane (vertical) vibrations that are sensed with the finger pads. When the tactile elements are formed into a 2D array, information can be conveyed to the user by varying the pattern of vibrations in space and time. Analytical models and finite element analysis were used to design individual tactile elements, which were implemented with PZT actuators and both SU-8 and 3D-printed scissor amplifiers. The measured displacements of these 3 mm × 10 mm, MEMS-enabled tactile elements exceed 10 µm, in agreement with models, with measured forces exceeding 45 mN. The performance of the MEMS-enabled tactile elements is compared with the performance of larger, fully-macroscale tactile elements to demonstrate the scale dependence of the devices. The creation of a 28-element prototype is also reported, and the qualitative user experience with the individual tactile elements and displays is described.

Infrared remote sensing of hazardous vapours: surveillance of public areas during the FIFA Football World Cup 2006

NASA Astrophysics Data System (ADS)

Harig, Roland; Matz, Gerhard; Rusch, Peter; Gerhard, Hans-Hennig; Gerhard, Jörn-Hinnrich; Schlabs, Volker

2007-04-01

The German ministry of the interior, represented by the civil defence agency BBK, established analytical task forces for the analysis of released chemicals in the case of fires, chemical accidents, terrorist attacks, or war. One of the first assignments of the task forces was the provision of analytical services during the football world cup 2006. One part of the equipment of these emergency response forces is a remote sensing system that allows identification and visualisation of hazardous clouds from long distances, the scanning infrared gas imaging system SIGIS 2. The system is based on an interferometer with a single detector element in combination with a telescope and a synchronised scanning mirror. The system allows 360° surveillance. The system is equipped with a video camera and the results of the analyses of the spectra are displayed by an overlay of a false colour image on the video image. This allows a simple evaluation of the position and the size of a cloud. The system was deployed for surveillance of stadiums and public viewing areas, where large crowds watched the games. Although no intentional or accidental releases of hazardous gases occurred in the stadiums and in the public viewing areas, the systems identified and located various foreign gases in the air.

Thermal effects on nonlinear vibration of a carbon nanotube-based mass sensor using finite element analysis

NASA Astrophysics Data System (ADS)

Kang, Dong-Keun; Kim, Chang-Wan; Yang, Hyun-Ik

2017-01-01

In the present study we carried out a dynamic analysis of a CNT-based mass sensor by using a finite element method (FEM)-based nonlinear analysis model of the CNT resonator to elucidate the combined effects of thermal effects and nonlinear oscillation behavior upon the overall mass detection sensitivity. Mass sensors using carbon nanotube (CNT) resonators provide very high sensing performance. Because CNT-based resonators can have high aspect ratios, they can easily exhibit nonlinear oscillation behavior due to large displacements. Also, CNT-based devices may experience high temperatures during their manufacture and operation. These geometrical nonlinearities and temperature changes affect the sensing performance of CNT-based mass sensors. However, it is very hard to find previous literature addressing the detection sensitivity of CNT-based mass sensors including considerations of both these nonlinear behaviors and thermal effects. We modeled the nonlinear equation of motion by using the von Karman nonlinear strain-displacement relation, taking into account the additional axial force associated with the thermal effect. The FEM was employed to solve the nonlinear equation of motion because it can effortlessly handle the more complex geometries and boundary conditions. A doubly clamped CNT resonator actuated by distributed electrostatic force was the configuration subjected to the numerical experiments. Thermal effects upon the fundamental resonance behavior and the shift of resonance frequency due to attached mass, i.e., the mass detection sensitivity, were examined in environments of both high and low (or room) temperature. The fundamental resonance frequency increased with decreasing temperature in the high temperature environment, and increased with increasing temperature in the low temperature environment. The magnitude of the shift in resonance frequency caused by an attached mass represents the sensing performance of a mass sensor, i.e., its mass detection sensitivity, and it can be seen that this shift is affected by the temperature change and the amount of electrostatic force. The thermal effects on the mass detection sensitivity are intensified in the linear oscillation regime and increase with increasing CNT length; this intensification can either improve or worsen the detection sensitivity.

A novel microbial fuel cell sensor with biocathode sensing element.

PubMed

Jiang, Yong; Liang, Peng; Liu, Panpan; Wang, Donglin; Miao, Bo; Huang, Xia

2017-08-15

The traditional microbial fuel cell (MFC) sensor with bioanode as sensing element delivers limited sensitivity to toxicity monitoring, restricted application to only anaerobic and organic rich water body, and increased potential fault warning to the combined shock of organic matter/toxicity. In this study, the biocathode for oxygen reduction reaction was employed for the first time as the sensing element in MFC sensor for toxicity monitoring. The results shown that the sensitivity of MFC sensor with biocathode sensing element (7.4±2.0 to 67.5±4.0mA% -1 cm -2 ) was much greater than that showed by bioanode sensing element (3.4±1.5 to 5.5±0.7mA% -1 cm -2 ). The biocathode sensing element achieved the lowest detection limit reported to date using MFC sensor for formaldehyde detection (0.0005%), while the bioanode was more applicable for higher concentration (>0.0025%). There was a quicker response of biocathode sensing element with the increase of conductivity and dissolved oxygen (DO). The biocathode sensing element made the MFC sensor directly applied to clean water body monitoring, e.g., drinking water and reclaimed water, without the amending of background organic matter, and it also decreased the warning failure when challenged by a combined shock of organic matter/toxicity. Copyright © 2017 Elsevier B.V. All rights reserved.

Linnehan on EVA 2 - during Expedition 16 / STS-123 Joint Operations

NASA Image and Video Library

2008-03-16

S123-E-006790 (15/16 March 2008) --- Astronauts Mike Foreman and Rick Linnehan (partially out of frame), both STS-123 mission specialists, participate in the mission's second scheduled session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the 7-hour, 8-minute spacewalk, Linnehan and Foreman, assembled the stick-figure-shaped Dextre, also known as the Special Purpose Dextrous Manipulator (SPDM), a task that included attaching its two arms. Designed for station maintenance and service, Dextre is capable of sensing forces and movement of objects it is manipulating. It can automatically compensate for those forces and movements to ensure an object is moved smoothly. Dextre is the final element of the station's Mobile Servicing System.

Linnehan and Foreman on EVA 2 - during Expedition 16 / STS-123 Joint Operations

NASA Image and Video Library

2008-03-16

S123-E-006788 (15/16 March 2008) --- Astronauts Mike Foreman (left) and Rick Linnehan, both STS-123 mission specialists, participate in the mission's second scheduled session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the 7-hour, 8-minute spacewalk, Linnehan and Foreman, assembled the stick-figure-shaped Dextre, also known as the Special Purpose Dextrous Manipulator (SPDM), a task that included attaching its two arms. Designed for station maintenance and service, Dextre is capable of sensing forces and movement of objects it is manipulating. It can automatically compensate for those forces and movements to ensure an object is moved smoothly. Dextre is the final element of the station's Mobile Servicing System.

Linnehan and Foreman on EVA 2 - during Expedition 16 / STS-123 Joint Operations

NASA Image and Video Library

2008-03-16

S123-E-006781 (15/16 March 2008) --- Astronauts Rick Linnehan (right) and Mike Foreman, both STS-123 mission specialists, participate in the mission's second scheduled session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the 7-hour, 8-minute spacewalk, Linnehan and Foreman, assembled the stick-figure-shaped Dextre, also known as the Special Purpose Dextrous Manipulator (SPDM), a task that included attaching its two arms. Designed for station maintenance and service, Dextre is capable of sensing forces and movement of objects it is manipulating. It can automatically compensate for those forces and movements to ensure an object is moved smoothly. Dextre is the final element of the station's Mobile Servicing System.

Force sensing micro-forceps with integrated fiber Bragg grating for vitreoretinal surgery

NASA Astrophysics Data System (ADS)

He, Xingchi; Balicki, Marcin A.; Kang, Jin U.; Gehlbach, Peter L.; Handa, James T.; Taylor, Russell H.; Iordachita, Iulian I.

2012-01-01

Vitreoretinal surgery is a technically demanding ophthalmologic discipline. One of the main technical challenges in vitreoretinal surgery is the lack of force sensing since the surgical maneuvers fall below the human sensory threshold. Previously, a 2-degree-of-freedom (DOF) force sensing instrument with a surgical pick was developed and tested. However, a more commonly used instrument for vitreoretinal surgery is the forceps, with which a surgeon can easily grasp and delaminate the scar tissue. We have designed, fabricated and calibrated a novel 20-gauge (Ga) microsurgical instrument with a 2-DOF force sensing forceps. Three fiber Bragg grating (FBG) sensors are integrated into the customized AlconTM forceps tip. The redundant sensor configuration provides good compensation for temperature-related drift. The calibration data show that the tool can provide a force resolution of 0.25 mN. In order to test the functionality and performance, the forceps was evaluated in inner shell membrane peeling experiments with chicken embryos as well as in in-vivo rabbit experiments. The instrument has demonstrated the capability of being applied in the clinical environment, with consistent force measurements. The force exerted in inner shell membrane peeling is from 6.07 to 34.65 mN. The development of the 2-DOF force sensing micro-forceps has shown that the fabrication process is feasible and reliable, and it can be used to develop a future 3-DOF force sensing tool.

Distributed sensing signal analysis of deformable plate/membrane mirrors

NASA Astrophysics Data System (ADS)

Lu, Yifan; Yue, Honghao; Deng, Zongquan; Tzou, Hornsen

2017-11-01

Deformable optical mirrors usually play key roles in aerospace and optical structural systems applied to space telescopes, radars, solar collectors, communication antennas, etc. Limited by the payload capacity of current launch vehicles, the deformable mirrors should be lightweight and are generally made of ultra-thin plates or even membranes. These plate/membrane mirrors are susceptible to external excitations and this may lead to surface inaccuracy and jeopardize relevant working performance. In order to investigate the modal vibration characteristics of the mirror, a piezoelectric layer is fully laminated on its non-reflective side to serve as sensors. The piezoelectric layer is segmented into infinitesimal elements so that microscopic distributed sensing signals can be explored. In this paper, the deformable mirror is modeled as a pre-tensioned plate and membrane respectively and sensing signal distributions of the two models are compared. Different pre-tensioning forces are also applied to reveal the tension effects on the mode shape and sensing signals of the mirror. Analytical results in this study could be used as guideline of optimal sensor/actuator placement for deformable space mirrors.

Design Optimisation of a Magnetic Field Based Soft Tactile Sensor

PubMed Central

Raske, Nicholas; Kow, Junwai; Alazmani, Ali; Ghajari, Mazdak; Culmer, Peter; Hewson, Robert

2017-01-01

This paper investigates the design optimisation of a magnetic field based soft tactile sensor, comprised of a magnet and Hall effect module separated by an elastomer. The aim was to minimise sensitivity of the output force with respect to the input magnetic field; this was achieved by varying the geometry and material properties. Finite element simulations determined the magnetic field and structural behaviour under load. Genetic programming produced phenomenological expressions describing these responses. Optimisation studies constrained by a measurable force and stable loading conditions were conducted; these produced Pareto sets of designs from which the optimal sensor characteristics were selected. The optimisation demonstrated a compromise between sensitivity and the measurable force, a fabricated version of the optimised sensor validated the improvements made using this methodology. The approach presented can be applied in general for optimising soft tactile sensor designs over a range of applications and sensing modes. PMID:29099787

Design and calibration of a six-axis MEMS sensor array for use in scoliosis correction surgery

NASA Astrophysics Data System (ADS)

Benfield, David; Yue, Shichao; Lou, Edmond; Moussa, Walied A.

2014-08-01

A six-axis sensor array has been developed to quantify the 3D force and moment loads applied in scoliosis correction surgery. Initially this device was developed to be applied during scoliosis correction surgery and augmented onto existing surgical instrumentation, however, use as a general load sensor is also feasible. The development has included the design, microfabrication, deployment and calibration of a sensor array. The sensor array consists of four membrane devices, each containing piezoresistive sensing elements, generating a total of 16 differential voltage outputs. The calibration procedure has made use of a custom built load application frame, which allows quantified forces and moments to be applied and compared to the outputs from the sensor array. Linear or non-linear calibration equations are generated to convert the voltage outputs from the sensor array back into 3D force and moment information for display or analysis.

Simulation of a sensor array for multiparameter measurements at the prosthetic limb interface

NASA Astrophysics Data System (ADS)

Rowe, Gabriel I.; Mamishev, Alexander V.

2004-07-01

Sensitive skin is a highly desired device for biomechanical devices, wearable computing, human-computer interfaces, exoskeletons, and, most pertinent to this paper, for lower limb prosthetics. The measurement of shear stress is very important because shear effects are key factors in developing surface abrasions and pressure sores in paraplegics and users of prosthetic/orthotic devices. A single element of a sensitive skin is simulated and characterized in this paper. Conventional tactile sensors are designed for measurement of the normal stress only, which is inadequate for comprehensive assessment of surface contact conditions. The sensitive skin discussed here is a flexible array capable of sensing shear and normal forces, as well as humidity and temperature on each element.

Noise-Enhanced Eversion Force Sense in Ankles With or Without Functional Instability.

PubMed

Ross, Scott E; Linens, Shelley W; Wright, Cynthia J; Arnold, Brent L

2015-08-01

Force sense impairments are associated with functional ankle instability. Stochastic resonance stimulation (SRS) may have implications for correcting these force sense deficits. To determine if SRS improved force sense. Case-control study. Research laboratory. Twelve people with functional ankle instability (age = 23 ± 3 years, height = 174 ± 8 cm, mass = 69 ± 10 kg) and 12 people with stable ankles (age = 22 ± 2 years, height = 170 ± 7 cm, mass = 64 ± 10 kg). The eversion force sense protocol required participants to reproduce a targeted muscle tension (10% of maximum voluntary isometric contraction). This protocol was assessed under SRSon and SRSoff (control) conditions. During SRSon, random subsensory mechanical noise was applied to the lower leg at a customized optimal intensity for each participant. Constant error, absolute error, and variable error measures quantified accuracy, overall performance, and consistency of force reproduction, respectively. With SRS, we observed main effects for force sense absolute error (SRSoff = 1.01 ± 0.67 N, SRSon = 0.69 ± 0.42 N) and variable error (SRSoff = 1.11 ± 0.64 N, SRSon = 0.78 ± 0.56 N) (P < .05). No other main effects or treatment-by-group interactions were found (P > .05). Although SRS reduced the overall magnitude (absolute error) and variability (variable error) of force sense errors, it had no effect on the directionality (constant error). Clinically, SRS may enhance muscle tension ability, which could have treatment implications for ankle stability.

Galerkin finite element scheme for magnetostrictive structures and composites

NASA Astrophysics Data System (ADS)

Kannan, Kidambi Srinivasan

The ever increasing-role of magnetostrictives in actuation and sensing applications is an indication of their importance in the emerging field of smart structures technology. As newer, and more complex, applications are developed, there is a growing need for a reliable computational tool that can effectively address the magneto-mechanical interactions and other nonlinearities in these materials and in structures incorporating them. This thesis presents a continuum level quasi-static, three-dimensional finite element computational scheme for modeling the nonlinear behavior of bulk magnetostrictive materials and particulate magnetostrictive composites. Models for magnetostriction must deal with two sources of nonlinearities-nonlinear body forces/moments in equilibrium equations governing magneto-mechanical interactions in deformable and magnetized bodies; and nonlinear coupled magneto-mechanical constitutive models for the material of interest. In the present work, classical differential formulations for nonlinear magneto-mechanical interactions are recast in integral form using the weighted-residual method. A discretized finite element form is obtained by applying the Galerkin technique. The finite element formulation is based upon three dimensional eight-noded (isoparametric) brick element interpolation functions and magnetostatic infinite elements at the boundary. Two alternative possibilities are explored for establishing the nonlinear incremental constitutive model-characterization in terms of magnetic field or in terms of magnetization. The former methodology is the one most commonly used in the literature. In this work, a detailed comparative study of both methodologies is carried out. The computational scheme is validated, qualitatively and quantitatively, against experimental measurements published in the literature on structures incorporating the magnetostrictive material Terfenol-D. The influence of nonlinear body forces and body moments of magnetic origin, on the response of magnetostrictive structures to complex mechanical and magnetic loading conditions, is carefully examined. While monolithic magnetostrictive materials have been commercially-available since the late eighties, attention in the smart structures research community has recently focussed upon building and using magnetostrictive particulate composite structures for conventional actuation applications and novel sensing methodologies in structural health monitoring. A particulate magnetostrictive composite element has been developed in the present work to model such structures. This composite element incorporates interactions between magnetostrictive particles by combining a numerical micromechanical analysis based on magneto-mechanical Green's functions, with a homogenization scheme based upon the Mori-Tanaka approach. This element has been applied to the simulation of particulate actuators and sensors reported in the literature. Simulation results are compared to experimental data for validation purposes. The computational schemes developed, for bulk materials and for composites, are expected to be of great value to researchers and designers of novel applications based on magnetostrictives.

Development of a Drilling Simulator for Dental Implant Surgery.

PubMed

Kinoshita, Hideaki; Nagahata, Masahiro; Takano, Naoki; Takemoto, Shinji; Matsunaga, Satoru; Abe, Shinichi; Yoshinari, Masao; Kawada, Eiji

2016-01-01

The aim of this study was to develop and evaluate a dental implant surgery simulator that allows learners to experience the drilling forces necessary to perform an osteotomy in the posterior mandibular bone. The simulator contains a force-sensing device that receives input and counteracts this force, which is felt as resistance by the user. The device consists of an actuator, a load cell, and a control unit. A mandibular bone model was fabricated in which the predicted forces necessary to drill the cortical and trabecular bone were determined via micro CT image-based 3D finite element analysis. The simulator was evaluated by five dentists from the Department of Implantology at Tokyo Dental College. The ability of the evaluators to distinguish the drilling resistance through different regions of the mandibular bone was investigated. Of the five dentists, four sensed the change in resistance when the drill perforated the upper cortical bone. All five dentists were able to detect when the drill made contact with lingual cortical bone and when the lingual bone was perforated. This project successfully developed a dental implant surgery simulator that allows users to experience the forces necessary to drill through types of bone encountered during osteotomy. Furthermore, the researchers were able to build a device by which excessive drilling simulates a situation in which the lingual cortical bone is perforated--a situation that could lead to negative repercussions in a clinical setting. The simulator was found to be useful to train users to recognize the differences in resistance when drilling through the mandibular bone.

Apparatus for providing sensory substitution of force feedback

NASA Technical Reports Server (NTRS)

Massimino, Michael J. (Inventor); Sheridan, Thomas B. (Inventor)

1995-01-01

A feedback apparatus for an operator to control an effector that is remote from the operator to interact with a remote environment has a local input device to be manipulated by the operator. Sensors in the effector's environment are capable of sensing the amplitude of forces arising between the effector and its environment, the direction of application of such forces, or both amplitude and direction. A feedback signal corresponding to such a component of the force, is generated and transmitted to the environment of the operator. The signal is transduced into an auditory sensory substitution signal to which the operator is sensitive. Sound production apparatus present the auditory signal to the operator. The full range of the force amplitude may be represented by a single, audio speaker. Auditory display elements may be stereo headphones or free standing audio speakers, numbering from one to many more than two. The location of the application of the force may also be specified by the location of audio speakers that generate signals corresponding to specific forces. Alternatively, the location may be specified by the frequency of an audio signal, or by the apparent location of an audio signal, as simulated by a combination of signals originating at different locations.

Six-axis orthodontic force and moment sensing system for dentist technique training.

PubMed

Midorikawa, Yoshiyuki; Takemura, Hiroshi; Mizoguchi, Hiroshi; Soga, Kohei; Kamimura, Masao; Suga, Kazuhiro; Wei-Jen Lai; Kanno, Zuisei; Uo, Motohiro

2016-08-01

The purpose of this study is to develop a sensing system device that measures three-axis orthodontic forces and three-axis orthodontic moments for dentist training. The developed sensing system is composed of six-axis force sensors, action sticks, sliders, and tooth models. The developed system also simulates various types of tooth row shape patterns in orthodontic operations, and measures a 14 × 6 axis orthodontic force and moment from tooth models simultaneously. The average force and moment error per loaded axis were 2.06 % and 2.00 %, respectively.

Design and Optimization of Nanomaterials for Sensing Applications

NASA Astrophysics Data System (ADS)

Sanderson, Robert Noboru

Nanomaterials, materials with one or more of their dimensions on the nanoscale, have emerged as an important field in the development of next-generation sensing systems. Their high surface-to-volume ratio makes them useful for sensing, but also makes them sensitive to processing defects and inherent material defects. To develop and optimize these systems, it is thus necessary to characterize these defects to understand their origin and how to work around them. Scanning probe microscopy (SPM) techniques like atomic force microscopy (AFM) and scanning tunneling microscopy (STM) are important characterization methods which can measure nanoscale topography and electronic structure. These methods are appealing in nanomaterial systems because they are non-damaging and provide local, high-resolution data, and so are capable of detecting nanoscale features such as single defect sites. There are difficulties, however, in the interpretation of SPM data. For instance, AFM-based methods are prone to experimental artifacts due to long-range interactions, such as capacitive crosstalk in Kelvin probe force microscopy (KPFM), and artifacts due to the finite size of the probe tip, such as incorrect surface tracking at steep topographical features. Mechanical characterization (via force spectroscopy) of nanomaterials with significant nanoscale variations, such as tethered lipid bilayer membranes (tLBMs), is also difficult since variations in the bulk system's mechanical behavior must be distinguished from local fluctuations. Additionally, interpretation of STM data is non-trivial due to local variations in electron density in addition to topographical variations. In this thesis we overcome some limitations of SPM methods by supplementing them with additional surface analytical methods as well as computational methods, and we characterize several nanomaterial systems. Current-carrying vapor-liquid-solid Si nanowires (useful for interdigitated-electrode-based sensors) are characterized using finite-element-method (FEM)-supplemented KPFM to retrieve useful information about processing defects, contact resistance, and the primary charge carriers. Next, a tLBM system's stiffness and the stiffness' dependence on tethering molecule concentration is measured using statistical analysis of thousands of AFM force spectra, demonstrating a biosensor-compatible system with a controllable bulk rigidity. Finally, we utilize surface analytical techniques to inform the development of a novel three-dimensional graphene system for sensing applications.

Enhanced radiation detectors using luminescent materials

DOEpatents

Vardeny, Zeev V.; Jeglinski, Stefan A.; Lane, Paul A.

2001-01-01

A radiation detecting device comprising a radiation sensing element, and a layer of luminescent material to expand the range of wavelengths over which the sensing element can efficiently detect radiation. The luminescent material being selected to absorb radiation at selected wavelengths, causing the luminescent material to luminesce, and the luminescent radiation being detected by the sensing element. Radiation sensing elements include photodiodes (singly and in arrays), CCD arrays, IR detectors and photomultiplier tubes. Luminescent materials include polymers, oligomers, copolymers and porphyrines, Luminescent layers include thin films, thicker layers, and liquid polymers.

Magnetic Actuator Modelling for Rotating Machinery Analysis

NASA Astrophysics Data System (ADS)

Mendes, Ricardo Ugliara; de Castro, Hélio Fiori; Cavalca, Kátia Lucchesi; Ferreira, Luiz Otávio Saraiva

Rotating machines have a wide range of application such as airplanes, factories, laboratories and power plants. Lately, with computer aid design, shafts finite element models including bearings, discs, seals and couplings have been developed, allowing the prediction of the machine behavior. In order to keep confidence during operation, it is necessary to monitor these systems, trying to predict future failures. One of the most applied technique for this purpose is the modal analysis. It consists of applying a perturbation force into the system and then to measure its response. However, there is a difficulty that brings limitations to the excitation of systems with rotating shafts when using impact hammers or shakers, once due to friction, undesired tangential forces and noise can be present in the measurements. Therefore, the study of a non-contact technique of external excitation becomes of high interest. In this sense, the present work deals with the study and development of a finite element model for rotating machines using a magnetic actuator as an external excitation source. This work also brings numerical simulations where the magnetic actuator was used to obtain the frequency response function of the rotating system.

Cooperative unfolding of distinctive mechanoreceptor domains transduces force into signals

PubMed Central

Ju, Lining; Chen, Yunfeng; Xue, Lingzhou; Du, Xiaoping; Zhu, Cheng

2016-01-01

How cells sense their mechanical environment and transduce forces into biochemical signals is a crucial yet unresolved question in mechanobiology. Platelets use receptor glycoprotein Ib (GPIb), specifically its α subunit (GPIbα), to signal as they tether and translocate on von Willebrand factor (VWF) of injured arterial surfaces against blood flow. Force elicits catch bonds to slow VWF–GPIbα dissociation and unfolds the GPIbα leucine-rich repeat domain (LRRD) and juxtamembrane mechanosensitive domain (MSD). How these mechanical processes trigger biochemical signals remains unknown. Here we analyze these extracellular events and the resulting intracellular Ca2+ on a single platelet in real time, revealing that LRRD unfolding intensifies Ca2+ signal whereas MSD unfolding affects the type of Ca2+ signal. Therefore, LRRD and MSD are analog and digital force transducers, respectively. The >30 nm macroglycopeptide separating the two domains transmits force on the VWF–GPIbα bond (whose lifetime is prolonged by LRRD unfolding) to the MSD to enhance its unfolding, resulting in unfolding cooperativity at an optimal force. These elements may provide design principles for a generic mechanosensory protein machine. DOI: http://dx.doi.org/10.7554/eLife.15447.001 PMID:27434669

Granular Contact Forces: Proof of "Self-Ergodicity" by Generalizing Boltzmann's Stosszahlansatz and H Theorem

NASA Technical Reports Server (NTRS)

Metzger, Philip T.

2006-01-01

Ergodicity is proved for granular contact forces. To obtain this proof from first principles, this paper generalizes Boltzmann's stosszahlansatz (molecular chaos) so that it maintains the necessary correlations and symmetries of granular packing ensembles. Then it formally counts granular contact force states and thereby defines the proper analog of Boltzmann's H functional. This functional is used to prove that (essentially) all static granular packings must exist at maximum entropy with respect to their contact forces. Therefore, the propagation of granular contact forces through a packing is a truly ergodic process in the Boltzmannian sense, or better, it is self-ergodic. Self-ergodicity refers to the non-dynamic, internal relationships that exist between the layer-by-layer and column-by-column subspaces contained within the phase space locus of any particular granular packing microstate. The generalized H Theorem also produces a recursion equation that may be solved numerically to obtain the density of single particle states and hence the distribution of granular contact forces corresponding to the condition of self-ergodicity. The predictions of the theory are overwhelmingly validated by comparison to empirical data from discrete element modeling.

Linnehan and Foreman on EVA 2 - during Expedition 16 / STS-123 Joint Operations

NASA Image and Video Library

2008-03-16

S123-E-006787 (15/16 March 2008) --- Astronauts Mike Foreman and Rick Linnehan (partially out of frame), both STS-123 mission specialists, participate in the mission's second scheduled session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the 7-hour, 8-minute spacewalk, Linnehan and Foreman, assembled the stick-figure-shaped Dextre, also known as the Special Purpose Dextrous Manipulator (SPDM), a task that included attaching its two arms. Designed for station maintenance and service, Dextre is capable of sensing forces and movement of objects it is manipulating. It can automatically compensate for those forces and movements to ensure an object is moved smoothly. Dextre is the final element of the station's Mobile Servicing System.

The Cytoskeleton and Force Response Mechanisms

NASA Technical Reports Server (NTRS)

Allen, Philip Goodwin

2003-01-01

The long term aim of this project was to define the mechanisms by which cells sense and respond to the physical forces experienced at 1g and missing in microgravity. Identification and characterization of the elements of the cells force response mechanism could provide pathways and molecules to serve as targets for pharmacological intervention to mitigate the pathologic effects of microgravity. Mechanical forces experienced by the organism can be transmitted to cells through molecules that allow cells to bind to the extracellular matrix and through other types of molecules which bind cells to each other. These molecules are coupled in large complexes of proteins to structural elements such as the actin cytoskeleton that give the cell the ability to sense, resist and respond to force. Application of small forces to tissue culture cells causes local elevation of intracellular calcium through stretch activated ion channels, increased tyrosine phosphorylation and a restructuring of the actin cytoskeleton. Using collagen coated iron oxide beads and strong magnets, we can apply different levels of force to cells in culture. We have found that force application causes the cells to polymerize actin at the site of mechanical deformation and unexpectedly, to depolymerize actin across the rest of the cell. Observations of GFP- actin expressing cells demonstrate that actin accumulates at the site of deformation within the first five minutes of force application and is maintained for many tens of minutes after force is removed. Consistent with the reinforcement of the cytoskeletal structures underlying the integrin-bead interaction, force also alters the motion of bound magnetic beads. This effect is seen following the removal of the magnetic field, and is only partially ablated by actin disruption with cytochalsin B. While actin is polymerizing locally at the site of force application, force also stimulates a global reduction in actin filament content within the cells. We have examined the roles of several actin filament disassembly factors in the global reduction of cellular actin filaments. The calcium regulated actin filament severing protein gelsolin is not necessary for the increased actin turnover, as cells derived from gelsolin null and wildtype mice still show a reduction in total actin filament content. Instead, our work suggests that the actin binding protein cofilin may be important for these changes in actin dynamics. Cofilin binds to and enhances the disassembly of actin filaments. Using immunological methods, we observe transient changes in the phosphorylation state of cofilin upon force application that suggests that cofilin may mediate actin filament turnover. Early after force application, cofilin is transiently dephosphorylated, activating its actin disassembly activity. Subsequently, we find a hyper-phosphorylation of cofilin, rendering it inactive. This reduction in cofilin activity may explain the stability of the force induced actin structuttes. In testing this hypothesis, we aimed to generate cells that express the constituitively active kinase (LIM-kinase) that phosphorylates cofilin. lnidial attempts in the cell lines used for the our previous studies proved unsuccessful. While we prepare this work for pubication, we are continuing to study other cell lines and tissue sources to determine whether they show a reduction in F-actin content after force application.

Direct current force sensing device based on compressive spring, permanent magnet, and coil-wound magnetostrictive/piezoelectric laminate.

PubMed

Leung, Chung Ming; Or, Siu Wing; Ho, S L

2013-12-01

A force sensing device capable of sensing dc (or static) compressive forces is developed based on a NAS106N stainless steel compressive spring, a sintered NdFeB permanent magnet, and a coil-wound Tb(0.3)Dy(0.7)Fe(1.92)/Pb(Zr, Ti)O3 magnetostrictive∕piezoelectric laminate. The dc compressive force sensing in the device is evaluated theoretically and experimentally and is found to originate from a unique force-induced, position-dependent, current-driven dc magnetoelectric effect. The sensitivity of the device can be increased by increasing the spring constant of the compressive spring, the size of the permanent magnet, and/or the driving current for the coil-wound laminate. Devices of low-force (20 N) and high-force (200 N) types, showing high output voltages of 262 and 128 mV peak, respectively, are demonstrated at a low driving current of 100 mA peak by using different combinations of compressive spring and permanent magnet.

A Quad-Cantilevered Plate micro-sensor for intracranial pressure measurement.

PubMed

Lalkov, Vasko; Qasaimeh, Mohammad A

2017-07-01

This paper proposes a new design for pressure-sensing micro-plate platform to bring higher sensitivity to a pressure sensor based on piezoresistive MEMS sensing mechanism. The proposed design is composed of a suspended plate having four stepped cantilever beams connected to its corners, and thus defined as Quad-Cantilevered Plate (QCP). Finite element analysis was performed to determine the optimal design for sensitivity and structural stability under a range of applied forces. Furthermore, a piezoresistive analysis was performed to calculate sensor sensitivity. Both the maximum stress and the change in resistance of the piezoresistor associated with the QCP were found to be higher compared to previously published designs, and linearly related to the applied pressure as desired. Therefore, the QCP demonstrates greater sensitivity, and could be potentially used as an efficient pressure sensor for intracranial pressure measurement.

Selective forces and mutational biases drive stop codon usage in the human genome: a comparison with sense codon usage.

PubMed

Trotta, Edoardo

2016-05-17

The three stop codons UAA, UAG, and UGA signal the termination of mRNA translation. As a result of a mechanism that is not adequately understood, they are normally used with unequal frequencies. In this work, we showed that selective forces and mutational biases drive stop codon usage in the human genome. We found that, in respect to sense codons, stop codon usage was affected by stronger selective forces but was less influenced by neutral mutational biases. UGA is the most frequent termination codon in human genome. However, UAA was the preferred stop codon in genes with high breadth of expression, high level of expression, AT-rich coding sequences, housekeeping functions, and in gene ontology categories with the largest deviation from expected stop codon usage. Selective forces associated with the breadth and the level of expression favoured AT-rich sequences in the mRNA region including the stop site and its proximal 3'-UTR, but acted with scarce effects on sense codons, generating two regions, upstream and downstream of the stop codon, with strongly different base composition. By favouring low levels of GC-content, selection promoted labile local secondary structures at the stop site and its proximal 3'-UTR. The compositional and structural context favoured by selection was surprisingly emphasized in the class of ribosomal proteins and was consistent with sequence elements that increase the efficiency of translational termination. Stop codons were also heterogeneously distributed among chromosomes by a mechanism that was strongly correlated with the GC-content of coding sequences. In human genome, the nucleotide composition and the thermodynamic stability of stop codon site and its proximal 3'-UTR are correlated with the GC-content of coding sequences and with the breadth and the level of gene expression. In highly expressed genes stop codon usage is compositionally and structurally consistent with highly efficient translation termination signals.

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

Verbiest, G. J., E-mail: Verbiest@physik.rwth-aachen.de; Zalm, D. J. van der; Oosterkamp, T. H.

The application of ultrasound in an Atomic Force Microscope (AFM) gives access to subsurface information. However, no commercially AFM exists that is equipped with this technique. The main problems are the electronic crosstalk in the AFM setup and the insufficiently strong excitation of the cantilever at ultrasonic (MHz) frequencies. In this paper, we describe the development of an add-on that provides a solution to these problems by using a special piezo element with a lowest resonance frequency of 2.5 MHz and by separating the electronic connection for this high frequency piezo element from all other connections. In this sense, wemore » support researches with the possibility to perform subsurface measurements with their existing AFMs and hopefully pave also the way for the development of a commercial AFM that is capable of imaging subsurface features with nanometer resolution.« less

Non-contact tamper sensing by electronic means

DOEpatents

Gritton, Dale G.

1993-01-01

A tamper-sensing system for an electronic tag 10 which is to be fixed to a surface 11 of an article 12, the tamper-sensing system comprising a capacitor having two non-contacting, capacitively-coupled elements 16, 19. Fixing of the body to the article will establish a precise location of the capacitor elements 16 and 19 relative to each other. When interrogated, the tag will generate a tamper-sensing signal having a value which is a function of the amount of capacity of the capacitor elements. The precise relative location of the capacitor elements cannot be duplicated if the tag is removed and affixed to a surrogate article having a fiducial capacitor element 19 fixed thereto. A very small displacement, in the order of 2-10 microns, of the capacitor elements relative to each other if the tag body is removed and fixed to a surrogate article will result in the tamper-sensing signal having a different, and detectable, value when the tag is interrogated.

A Two-Axis Direct Fluid Shear Stress Sensor

NASA Technical Reports Server (NTRS)

Adcock, Edward E.; Scott, Michael A.; Bajikar, Sateesh S.

2010-01-01

This innovation is a miniature or micro sized semiconductor sensor design that provides two axis direct non-intrusive measurement of skin friction or wall shear stress in fluid flow. The sensor is fabricated by micro-electro-mechanical system (MEMS) technology, enabling small size and low cost reproductions. The sensors have been fabricated by utilizing MEMS fabrication processes to bond a sensing element wafer to a fluid coupling wafer. This layering technique provides for an out of plane dimension that is on the same order of length as the inplane dimensions. The sensor design has the following characteristics: a shear force collecting plate with dimensions that can be tailored to various application specific requirements such as spatial resolution, temporal resolution and shear force range and resolution. This plate is located coplanar to both the sensor body and flow boundary, and is connected to a dual axis gimbal structure by a connecting column or lever arm. The dual axis gimbal structure has torsional hinges with embedded piezoresistive torsional strain gauges which provide a voltage output that is correlated to the applied shear stress (and excitation current) on force collection plate that is located on the flow boundary surface (hence the transduction method). This combination of design elements create a force concentration and resolution structure that enables the generation of a large stress on the strain gauge from the small shear stress on the flow boundary wall. This design as well as the use of back side electrical contacts establishes a non-intrusive method to quantitatively measure the shear force vector on aerodynamic bodies.

Strain field reconstruction on composite spars based on the identification of equivalent load conditions

NASA Astrophysics Data System (ADS)

Airoldi, A.; Marelli, L.; Bettini, P.; Sala, G.; Apicella, A.

2017-04-01

Technologies based on optical fibers provide the possibility of installing relatively dense networks of sensors that can perform effective strain sensing functions during the operational life of structures. A contemporary trend is the increasing adoption of composite materials in aerospace constructions, which leads to structural architectures made of large monolithic elements. The paper is aimed at showing the feasibility of a detailed reconstruction of the strain field in a composite spar, which is based on the development of reference finite element models and the identification of load modes, consisting of a parameterized set of forces. The procedure is described and assessed in ideal conditions. Thereafter, a surrogate model is used to obtain realistic representation of the data acquired by the strain sensing system, so that the developed procedure is evaluated considering local effects due to the introduction of loads, significant modelling discrepancy in the development of the reference model and the presence of measurement noise. Results show that the method can obtain a robust and quite detailed reconstruction of strain fields, even at the level of local distributions, of the internal forces in the spars and of the displacements, by identifying an equivalent set of load parameters. Finally, the trade-off between the number of sensor and the accuracy, and the optimal position of the sensors for a given maximum number of sensors is evaluated by performing a multi-objective optimization, thus showing that even a relative dense network of externally applied sensors can be used to achieve good quality results.

Development of haptic based piezoresistive artificial fingertip: Toward efficient tactile sensing systems for humanoids.

PubMed

TermehYousefi, Amin; Azhari, Saman; Khajeh, Amin; Hamidon, Mohd Nizar; Tanaka, Hirofumi

2017-08-01

Haptic sensors are essential devices that facilitate human-like sensing systems such as implantable medical devices and humanoid robots. The availability of conducting thin films with haptic properties could lead to the development of tactile sensing systems that stretch reversibly, sense pressure (not just touch), and integrate with collapsible. In this study, a nanocomposite based hemispherical artificial fingertip fabricated to enhance the tactile sensing systems of humanoid robots. To validate the hypothesis, proposed method was used in the robot-like finger system to classify the ripe and unripe tomato by recording the metabolic growth of the tomato as a function of resistivity change during a controlled indention force. Prior to fabrication, a finite element modeling (FEM) was investigated for tomato to obtain the stress distribution and failure point of tomato by applying different external loads. Then, the extracted computational analysis information was utilized to design and fabricate nanocomposite based artificial fingertip to examine the maturity analysis of tomato. The obtained results demonstrate that the fabricated conformable and scalable artificial fingertip shows different electrical property for ripe and unripe tomato. The artificial fingertip is compatible with the development of brain-like systems for artificial skin by obtaining periodic response during an applied load. Copyright © 2017. Published by Elsevier B.V.

(Re)creating community: Experiences of Older Women Forcibly Relocated During Apartheid

PubMed Central

Roos, Vera; Kolobe, Patricia Stockie; Keating, Norah

2014-01-01

This article explores sense of community with a group of older African women, who were forcibly relocated during apartheid. The situation of a marginalised group, with a history of disconnection from younger generations and from place, provides an opportunity to consider the relevance of community in later life. The research was conducted at a day centre for older people in the North West Province of South Africa, more than 50 years after forced relocations took place. Eleven older women (70 years and older) participated. Qualitative data were obtained through visual research methods and group discussions and were thematically analysed. Findings were that place and sense of belonging as well as elements of community were relevant. Participants reported limited connections to place in either childhood or current communities. Post relocation, a sense of belonging was expressed only in relation to a shared-interest community of peers that addressed their needs for safety, emotional support and instrumental care. Also, generational relations were strained, giving rise to a sense of loss of a community where both young and old were responsible for each other. Constrained resource communities have a profound impact on opportunities to create a sense of belonging. © 2013 The Authors. Journal of Community & Applied Social Psychology published by John Wiley & Sons Ltd. PMID:25253984

(Re)creating community: Experiences of Older Women Forcibly Relocated During Apartheid.

PubMed

Roos, Vera; Kolobe, Patricia Stockie; Keating, Norah

2014-01-01

This article explores sense of community with a group of older African women, who were forcibly relocated during apartheid. The situation of a marginalised group, with a history of disconnection from younger generations and from place, provides an opportunity to consider the relevance of community in later life. The research was conducted at a day centre for older people in the North West Province of South Africa, more than 50 years after forced relocations took place. Eleven older women (70 years and older) participated. Qualitative data were obtained through visual research methods and group discussions and were thematically analysed. Findings were that place and sense of belonging as well as elements of community were relevant. Participants reported limited connections to place in either childhood or current communities. Post relocation, a sense of belonging was expressed only in relation to a shared-interest community of peers that addressed their needs for safety, emotional support and instrumental care. Also, generational relations were strained, giving rise to a sense of loss of a community where both young and old were responsible for each other. Constrained resource communities have a profound impact on opportunities to create a sense of belonging. © 2013 The Authors. Journal of Community & Applied Social Psychology published by John Wiley & Sons Ltd.

Pressure sensing element based on the BN-graphene-BN heterostructure

NASA Astrophysics Data System (ADS)

Li, Mengwei; Wu, Chenggen; Zhao, Shiliang; Deng, Tao; Wang, Junqiang; Liu, Zewen; Wang, Li; Wang, Gao

2018-04-01

In this letter, we report a pressure sensing element based on the graphene-boron nitride (BN) heterostructure. The heterostructure consists of monolayer graphene sandwiched between two layers of vertically stacked dielectric BN nanofilms. The BN layers were used to protect the graphene layer from oxidation and pollution. Pressure tests were performed to investigate the characteristics of the BN-graphene-BN pressure sensing element. A sensitivity of 24.85 μV/V/mmHg is achieved in the pressure range of 130-180 kPa. After exposing the BN-graphene-BN pressure sensing element to the ambient environment for 7 days, the relative resistance change in the pressure sensing element is only 3.1%, while that of the reference open-faced graphene device without the BN protection layers is 15.7%. Thus, this strategy is promising for fabricating practical graphene pressure sensors with improved performance and stability.

Sensing Device with Whisker Elements

NASA Technical Reports Server (NTRS)

Hartmann, Mitra J. (Inventor); Solomon, Joseph H. (Inventor)

2013-01-01

A sensing device includes an elongated whisker element having a flexible cantilever region and a base region where a change in moment or curvature is generated by bending of the cantilever region when it contacts an object. One or more sensor elements cooperatively associated with the whisker element provide one or more output signals that is/are representative of two orthogonal components of change in moment or curvature at the whisker base region to permit determination of object distance, fluid velocity profile, or object contour (shape) with accounting for lateral slip of the whisker element and frictional characteristics of the object. Multiple sensing devices can be arranged in arrays in a manner to sense object contour without or with adjustment for lateral slip.

Sensing device with whisker elements

NASA Technical Reports Server (NTRS)

Hartmann, Mitra J. (Inventor); Solomon, Joseph H. (Inventor)

2010-01-01

A sensing device includes an elongated whisker element having a flexible cantilever region and a base region where a change in moment or curvature is generated by bending of the cantilever region when it contacts an object. One or more sensor elements cooperatively associated with the whisker element provide one or more output signals that is/are representative of two orthogonal components of change in moment or curvature at the whisker base region to permit determination of object distance, fluid velocity profile, or object contour (shape) with accounting for lateral slip of the whisker element and frictional characteristics of the object. Multiple sensing devices can be arranged in arrays in a manner to sense object contour without or with adjustment for lateral slip.

Development of instrumentation for measurements of two components of velocity with a single sensing element

NASA Astrophysics Data System (ADS)

Byers, C. P.; Fu, M. K.; Fan, Y.; Hultmark, M.

2018-02-01

A novel method of obtaining two orthogonal velocity components with high spatial and temporal resolution is investigated. Both components are obtained utilizing a single sensing nanoribbon by combining the two independent operating modes of classic hot wire anemometry and the newly discovered elastic filament velocimetry (EFV). In contrast to hot wire anemometry, EFV measures fluid velocity through correlating the fluid forcing with the internal strain of the wire. In order to utilize both modes of operation, a system that switches between the two operating modes is built and characterized, and the theoretically predicted sensing response time in water is compared to experimental results. The sensing system is capable of switching between the two modes of operation at a frequency of 100 kHz with minimal attenuation with an uncompensated repetition rate up to 3 kHz or up to 10 kHz utilizing modest signal compensation. While further characterization of the sensor performance in air is needed, this methodology enables a technique for obtaining well-resolved yet cost-efficient directional measurements of flow velocities which, for example, can be used for distributed measurements of velocity or measurements of turbulent stresses with excellent spatial resolution.

Methods and Research for Multi-Component Cutting Force Sensing Devices and Approaches in Machining

PubMed Central

Liang, Qiaokang; Zhang, Dan; Wu, Wanneng; Zou, Kunlin

2016-01-01

Multi-component cutting force sensing systems in manufacturing processes applied to cutting tools are gradually becoming the most significant monitoring indicator. Their signals have been extensively applied to evaluate the machinability of workpiece materials, predict cutter breakage, estimate cutting tool wear, control machine tool chatter, determine stable machining parameters, and improve surface finish. Robust and effective sensing systems with capability of monitoring the cutting force in machine operations in real time are crucial for realizing the full potential of cutting capabilities of computer numerically controlled (CNC) tools. The main objective of this paper is to present a brief review of the existing achievements in the field of multi-component cutting force sensing systems in modern manufacturing. PMID:27854322

Methods and Research for Multi-Component Cutting Force Sensing Devices and Approaches in Machining.

PubMed

Liang, Qiaokang; Zhang, Dan; Wu, Wanneng; Zou, Kunlin

2016-11-16

Multi-component cutting force sensing systems in manufacturing processes applied to cutting tools are gradually becoming the most significant monitoring indicator. Their signals have been extensively applied to evaluate the machinability of workpiece materials, predict cutter breakage, estimate cutting tool wear, control machine tool chatter, determine stable machining parameters, and improve surface finish. Robust and effective sensing systems with capability of monitoring the cutting force in machine operations in real time are crucial for realizing the full potential of cutting capabilities of computer numerically controlled (CNC) tools. The main objective of this paper is to present a brief review of the existing achievements in the field of multi-component cutting force sensing systems in modern manufacturing.

Force-dependent isomerization kinetics of a highly conserved proline switch modulates the mechanosensing region of filamin

PubMed Central

Rognoni, Lorenz; Möst, Tobias; Žoldák, Gabriel; Rief, Matthias

2014-01-01

Proline switches, controlled by cis–trans isomerization, have emerged as a particularly effective regulatory mechanism in a wide range of biological processes. In this study, we use single-molecule mechanical measurements to develop a full kinetic and energetic description of a highly conserved proline switch in the force-sensing domain 20 of human filamin and how prolyl isomerization modulates the force-sensing mechanism. Proline isomerization toggles domain 20 between two conformations. A stable cis conformation with slow unfolding, favoring the autoinhibited closed conformation of filamin’s force-sensing domain pair 20–21, and a less stable, uninhibited conformation promoted by the trans form. The data provide detailed insight into the folding mechanisms that underpin the functionality of this binary switch and elucidate its remarkable efficiency in modulating force-sensing, thus combining two previously unconnected regulatory mechanisms, proline switches and mechanosensing. PMID:24706888

A nano cold-wire for velocity measurements

NASA Astrophysics Data System (ADS)

Huang, Yi-Chun; Fu, Matthew; Fan, Yuyang; Byers, Clayton; Hultmark, Marcus

2016-11-01

We introduce a novel, strain-based sensor for both gaseous and liquid flows. The sensor consists of a free-standing, electrically conductive, nanoscale ribbon suspended between silicon supports. Due to its size, the nanoribbon deflects in flow under viscously dominated fluid forcing, which induces axial strain and a resistance change in the sensing element. The change in resistance can then be measured by a Wheatstone bridge, resulting in straightforward design and operation of the sensor. Since its operating principle is based on viscous fluid forcing, the sensor has high sensitivity especially in liquid or other highly viscous flows. A simple analytical model to understand the relation between forcing and strain is derived from the geometric and material constraints, and preliminary analysis using a low order model of the dynamic systems suggests that the sensor has a high frequency response. Lastly, a cylindrical structure to house the sensor with an axial and ventral channel to generate a pressure differential is being considered for typical velocimetry applications.

Multiplexed Force and Deflection Sensing Shell Membranes for Robotic Manipulators

NASA Technical Reports Server (NTRS)

Park, Yong-Lae; Black, Richard; Moslehi, Behzad; Cutkosky, Mark; Chau, Kelvin

2012-01-01

Force sensing is an essential requirement for dexterous robot manipulation, e.g., for extravehicular robots making vehicle repairs. Although strain gauges have been widely used, a new sensing approach is desirable for applications that require greater robustness, design flexibility including a high degree of multiplexibility, and immunity to electromagnetic noise. This invention is a force and deflection sensor a flexible shell formed with an elastomer having passageways formed by apertures in the shell, with an optical fiber having one or more Bragg gratings positioned in the passageways for the measurement of force and deflection.

A novel 4-DOF surgical instrument with modular joints and 6-Axis Force sensing capability.

PubMed

Li, Kun; Pan, Bo; Zhang, Fuhai; Gao, Wenpeng; Fu, Yili; Wang, Shuguo

2017-03-01

It is difficult for surgeons to exert appropriate forces during delicate operations due to lack of force feedback in robot-assisted minimally invasive surgery (RMIS). A 4-DOF surgical grasper with a modular wrist and 6-axis force sensing capability is developed. A grasper integrated with a miniature force and torque sensor based on the Stewart platform is designed, and a cable tension decomposition mechanism is designed to alleviate influence of the cable tension to the sensor. A modularized wrist consisting of four joint units is designed to facilitate integration of the sensor and eliminate coupled motion of the wrist. Sensing ranges of this instrument are ±10 N and ±160 N mm, and resolutions are 1.2% in radial directions, 5% in axial direction, and 4.2% in rotational directions. An ex vivo experiment shows that this instrument prototype successfully measures the interaction forces. A 4-DOF surgical instrument with modular joints and 6-axis force sensing capability is developed. This instrument can be used for force feedback in RMIS. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Linnehan and Foreman on EVA 2 - during Expedition 16 / STS-123 Joint Operations

NASA Image and Video Library

2008-03-16

S123-E-006786 (15/16 March 2008) --- Astronaut Rick Linnehan, STS-123 mission specialist, participates in the mission's second scheduled session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the 7-hour, 8-minute spacewalk, Linnehan and astronaut Mike Foreman (out of frame), mission specialist, assembled the stick-figure-shaped Dextre, also known as the Special Purpose Dextrous Manipulator (SPDM), a task that included attaching its two arms. Designed for station maintenance and service, Dextre is capable of sensing forces and movement of objects it is manipulating. It can automatically compensate for those forces and movements to ensure an object is moved smoothly. Dextre is the final element of the station's Mobile Servicing System. The blackness of space and Earth's horizon provide the backdrop for the scene.

Linnehan and Foreman on EVA 2 during STS-123 / Expedition 16 Joint Operations

NASA Image and Video Library

2008-03-16

S123-E-006400 (15/16 March 2008) --- Astronauts Rick Linnehan and Mike Foreman, both STS-123 mission specialists, participate in the mission's second scheduled session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the 7-hour, 8-minute spacewalk, Linnehan and Foreman, assembled the stick-figure-shaped Dextre, also known as the Special Purpose Dextrous Manipulator (SPDM), a task that included attaching its two arms. Designed for station maintenance and service, Dextre is capable of sensing forces and movement of objects it is manipulating. It can automatically compensate for those forces and movements to ensure an object is moved smoothly. Dextre is the final element of the station's Mobile Servicing System. The blackness of space and Earth's horizon provide the backdrop for the scene.

Linnehan and Foreman on EVA 2 during STS-123 / Expedition 16 Joint Operations

NASA Image and Video Library

2008-03-16

S123-E-006403 (15/16 March 2008) --- Astronauts Rick Linnehan and Mike Foreman, both STS-123 mission specialists, participate in the mission's second scheduled session of extravehicular activity (EVA) as construction and maintenance continue on the International Space Station. During the 7-hour, 8-minute spacewalk, Linnehan and Foreman, assembled the stick-figure-shaped Dextre, also known as the Special Purpose Dextrous Manipulator (SPDM), a task that included attaching its two arms. Designed for station maintenance and service, Dextre is capable of sensing forces and movement of objects it is manipulating. It can automatically compensate for those forces and movements to ensure an object is moved smoothly. Dextre is the final element of the station's Mobile Servicing System. The blackness of space and Earth's horizon provide the backdrop for the scene.

Mathematics and complex systems.

PubMed

Foote, Richard

2007-10-19

Contemporary researchers strive to understand complex physical phenomena that involve many constituents, may be influenced by numerous forces, and may exhibit unexpected or emergent behavior. Often such "complex systems" are macroscopic manifestations of other systems that exhibit their own complex behavior and obey more elemental laws. This article proposes that areas of mathematics, even ones based on simple axiomatic foundations, have discernible layers, entirely unexpected "macroscopic" outcomes, and both mathematical and physical ramifications profoundly beyond their historical beginnings. In a larger sense, the study of mathematics itself, which is increasingly surpassing the capacity of researchers to verify "by hand," may be the ultimate complex system.

The free and forced vibrations of structures using the finite dynamic element method. Ph.D. Thesis, Aug. 1991 Final Report

NASA Technical Reports Server (NTRS)

Fergusson, Neil J.

1992-01-01

In addition to an extensive review of the literature on exact and corrective displacement based methods of vibration analysis, a few theorems are proven concerning the various structural matrices involved in such analyses. In particular, the consistent mass matrix and the quasi-static mass matrix are shown to be equivalent, in the sense that the terms in their respective Taylor expansions are proportional to one another, and that they both lead to the same dynamic stiffness matrix when used with the appropriate stiffness matrix.

Method and apparatus for sensing a desired component of an incident magnetic field using magneto resistive elements biased in different directions

NASA Technical Reports Server (NTRS)

Pant, Bharat B. (Inventor); Wan, Hong (Inventor)

1999-01-01

A method and apparatus for sensing a desired component of a magnetic field using an isotropic magnetoresistive material. This is preferably accomplished by providing a bias field that is parallel to the desired component of the applied magnetic field. The bias field is applied in a first direction relative to a first set of magnetoresistive sensor elements, and in an opposite direction relative to a second set of magnetoresistive sensor elements. In this configuration, the desired component of the incident magnetic field adds to the bias field incident on the first set of magnetoresistive sensor elements, and subtracts from the bias field incident on the second set of magnetoresistive sensor elements. The magnetic field sensor may then sense the desired component of the incident magnetic field by simply sensing the difference in resistance of the first set of magnetoresistive sensor elements and the second set of magnetoresistive sensor elements.

Optimization study on the primary mirror lightweighting of a remote sensing instrument

NASA Astrophysics Data System (ADS)

Chan, Chia-Yen; Huang, Bo-Kai; You, Zhen-Ting; Chen, Yi-Cheng; Huang, Ting-Ming

2015-07-01

Remote sensing instrument (RSI) is used to take images for ground surface observation, which will be exposed to high vacuum, high temperature difference, gravity, 15 g-force and random vibration conditions and other harsh environments during operation. While designing a RSI optical system, not only the optical quality but also the strength of mechanical structure we should be considered. As a result, an optimization method is adopted to solve this engineering problem. In the study, a ZERODUR® mirror with a diameter of 466 mm has been chosen as the model and the optimization has been executed by combining the computer-aided design, finite element analysis, and parameter optimization software. The optimization is aimed to obtain the most lightweight mirror with maintaining structural rigidity and good optical quality. Finally, the optimum optical mirror with a lightweight ratio of 0.55 is attained successfully.

A comparison of force sensing techniques for planetary manipulation

NASA Technical Reports Server (NTRS)

Helmick, Daniel; Okon, Avi; DiCicco, Matt

2006-01-01

Five techniques for sensing forces with a manipulator are compared analytically and experimentally. The techniques compared are: a six-axis wrist force/torque sensor, joint torque sensors, link strain gauges, motor current sensors, and flexibility modeling. The accuracy and repeatability fo each technique is quantified and compared.

Lipid rafts sense and direct electric field-induced migration

PubMed Central

Lin, Bo-jian; Tsao, Shun-hao; Chen, Alex; Hu, Shu-Kai; Chao, Ling

2017-01-01

Endogenous electric fields (EFs) are involved in developmental regulation and wound healing. Although the phenomenon is known for more than a century, it is not clear how cells perceive the external EF. Membrane proteins, responding to electrophoretic and electroosmotic forces, have long been proposed as the sensing molecules. However, specific charge modification of surface proteins did not change cell migration motility nor directionality in EFs. Moreover, symmetric alternating current (AC) EF directs cell migration in a frequency-dependent manner. Due to their charge and ability to coalesce, glycolipids are therefore the likely primary EF sensor driving polarization of membrane proteins and intracellular signaling. We demonstrate that detergent-resistant membrane nanodomains, also known as lipid rafts, are the primary response element in EF sensing. The clustering and activation of caveolin and signaling proteins further stabilize raft structure and feed-forward downstream signaling events, such as rho and PI3K activation. Theoretical modeling supports the experimental results and predicts AC frequency-dependent cell and raft migration. Our results establish a fundamental mechanism for cell electrosensing and provide a role in lipid raft mechanotransduction. PMID:28739955

Lipid rafts sense and direct electric field-induced migration.

PubMed

Lin, Bo-Jian; Tsao, Shun-Hao; Chen, Alex; Hu, Shu-Kai; Chao, Ling; Chao, Pen-Hsiu Grace

2017-08-08

Endogenous electric fields (EFs) are involved in developmental regulation and wound healing. Although the phenomenon is known for more than a century, it is not clear how cells perceive the external EF. Membrane proteins, responding to electrophoretic and electroosmotic forces, have long been proposed as the sensing molecules. However, specific charge modification of surface proteins did not change cell migration motility nor directionality in EFs. Moreover, symmetric alternating current (AC) EF directs cell migration in a frequency-dependent manner. Due to their charge and ability to coalesce, glycolipids are therefore the likely primary EF sensor driving polarization of membrane proteins and intracellular signaling. We demonstrate that detergent-resistant membrane nanodomains, also known as lipid rafts, are the primary response element in EF sensing. The clustering and activation of caveolin and signaling proteins further stabilize raft structure and feed-forward downstream signaling events, such as rho and PI3K activation. Theoretical modeling supports the experimental results and predicts AC frequency-dependent cell and raft migration. Our results establish a fundamental mechanism for cell electrosensing and provide a role in lipid raft mechanotransduction.

The feasibility of utilizing remotely sensed data to assess and monitor oceanic gamefish

NASA Technical Reports Server (NTRS)

Savastano, K. J.; Leming, T. D.

1975-01-01

An investigation was conducted to establish the feasibility of utilizing remotely sensed data acquired from aircraft and satellite platforms to provide information concerning the distribution and abundance of oceanic gamefish. The data from the test area was jointly acquired by NASA, the Navy, the Air Force and NOAA/NMFS elements and private and professional fishermen in the northeastern Gulf of Mexico. The data collected has made it possible to identify fisheries significant environmental parameters for white marlin. Prediction models, based on catch data and surface truth information, were developed and demonstrated a potential for significantly reducing search by identifying areas that have a high probability of productivity. Three of the parameters utilized by the models, chlorophyll-a, sea surface temperature, and turbidity were inferred from aircraft sensor data and were tested. Effective use of Skylab data was inhibited by cloud cover and delayed delivery. Initial efforts toward establishing the feasibility of utilizing remotely sensed data to assess and monitor the distribution of oceanic gamefish has successfully identified fisheries significant oceanographic parameters and demonstrated the capability of remotely measuring most of the parameters.

Compact Hip-Force Sensor for a Gait-Assistance Exoskeleton System.

PubMed

Choi, Hyundo; Seo, Keehong; Hyung, Seungyong; Shim, Youngbo; Lim, Soo-Chul

2018-02-13

In this paper, we propose a compact force sensor system for a hip-mounted exoskeleton for seniors with difficulties in walking due to muscle weakness. It senses and monitors the delivered force and power of the exoskeleton for motion control and taking urgent safety action. Two FSR (force-sensitive resistors) sensors are used to measure the assistance force when the user is walking. The sensor system directly measures the interaction force between the exoskeleton and the lower limb of the user instead of a previously reported force-sensing method, which estimated the hip assistance force from the current of the motor and lookup tables. Furthermore, the sensor system has the advantage of generating torque in the walking-assistant actuator based on directly measuring the hip-assistance force. Thus, the gait-assistance exoskeleton system can control the delivered power and torque to the user. The force sensing structure is designed to decouple the force caused by hip motion from other directional forces to the sensor so as to only measure that force. We confirmed that the hip-assistance force could be measured with the proposed prototype compact force sensor attached to a thigh frame through an experiment with a real system.

Compact Hip-Force Sensor for a Gait-Assistance Exoskeleton System

PubMed Central

Choi, Hyundo; Seo, Keehong; Hyung, Seungyong; Shim, Youngbo; Lim, Soo-Chul

2018-01-01

In this paper, we propose a compact force sensor system for a hip-mounted exoskeleton for seniors with difficulties in walking due to muscle weakness. It senses and monitors the delivered force and power of the exoskeleton for motion control and taking urgent safety action. Two FSR (force-sensitive resistors) sensors are used to measure the assistance force when the user is walking. The sensor system directly measures the interaction force between the exoskeleton and the lower limb of the user instead of a previously reported force-sensing method, which estimated the hip assistance force from the current of the motor and lookup tables. Furthermore, the sensor system has the advantage of generating torque in the walking-assistant actuator based on directly measuring the hip-assistance force. Thus, the gait-assistance exoskeleton system can control the delivered power and torque to the user. The force sensing structure is designed to decouple the force caused by hip motion from other directional forces to the sensor so as to only measure that force. We confirmed that the hip-assistance force could be measured with the proposed prototype compact force sensor attached to a thigh frame through an experiment with a real system. PMID:29438300

Safe Tissue Manipulation in Retinal Microsurgery via Motorized Instruments with Force Sensing.

PubMed

Gonenc, Berk; Gehlbach, Peter; Taylor, Russell H; Iordachita, Iulian

2017-01-01

Retinal microsurgery involves careful manipulation of delicate tissues by applying very small amount of forces most of which lie below the tactile sensory threshold of the surgeons. Membrane peeling is a common task in this domain, where application of excessive peeling forces can easily lead to serious complications, hence needs to be avoided. To quantify tool-tissue interaction forces during retinal microsurgery, various force-sensing tools were developed based on fiber Bragg grating sensors, yet the most beneficial way of using the acquired force information is currently unknown. In this study, using a motorized force-sensing micro-forceps tool, we develop an assistive method that enhances safety during membrane peeling by automatically opening the forceps and releasing the tissue based on the detected peeling forces. Through peeling experiments using bandages, we demonstrate that our method can effectively maintain the peeling force at a safe level even in case of non-homogeneous adhesion properties of the membrane.

Evaluation of a Micro-Force Sensing Handheld Robot for Vitreoretinal Surgery.

PubMed

Gonenc, Berk; Balicki, Marcin A; Handa, James; Gehlbach, Peter; Riviere, Cameron N; Taylor, Russell H; Iordachita, Iulian

2012-12-20

Highly accurate positioning is fundamental to the performance of vitreoretinal microsurgery. Of vitreoretinal procedures, membrane peeling is among the most prone to complications since extremely delicate manipulation of retinal tissue is required. Associated tool-to-tissue interaction forces are usually below the threshold of human perception, and the surgical tools are moved very slowly, within the 0.1-0.5 mm/s range. During the procedure, unintentional tool motion and excessive forces can easily give rise to vision loss or irreversible damage to the retina. A successful surgery includes two key features: controlled tremor-free tool motion and control of applied force. In this study, we present the potential benefits of a micro-force sensing robot in vitreoretinal surgery. Our main contribution is implementing fiber Bragg grating based force sensing in an active tremor canceling handheld micromanipulator, known as Micron, to measure tool-to-tissue interaction forces in real time. Implemented auditory sensory substitution assists in reducing and limiting forces. In order to test the functionality and performance, the force sensing Micron was evaluated in peeling experiments with adhesive bandages and with the inner shell membrane from chicken eggs. Our findings show that the combination of active tremor canceling together with auditory sensory substitution is the most promising aid that keeps peeling forces below 7 mN with a significant reduction in 2-20 Hz oscillations.

Acetylcholine released by endothelial cells facilitates flow‐mediated dilatation

PubMed Central

Wilson, Calum; Lee, Matthew D.

2016-01-01

Key points The endothelium plays a pivotal role in the vascular response to chemical and mechanical stimuli.The endothelium is exquisitely sensitive to ACh, although the physiological significance of ACh‐induced activation of the endothelium is unknown.In the present study, we investigated the mechanisms of flow‐mediated endothelial calcium signalling.Our data establish that flow‐mediated endothelial calcium responses arise from the autocrine action of non‐neuronal ACh released by the endothelium. Abstract Circulating blood generates frictional forces (shear stress) on the walls of blood vessels. These frictional forces critically regulate vascular function. The endothelium senses these frictional forces and, in response, releases various vasodilators that relax smooth muscle cells in a process termed flow‐mediated dilatation. Although some elements of the signalling mechanisms have been identified, precisely how flow is sensed and transduced to cause the release of relaxing factors is poorly understood. By imaging signalling in large areas of the endothelium of intact arteries, we show that the endothelium responds to flow by releasing ACh. Once liberated, ACh acts to trigger calcium release from the internal store in endothelial cells, nitric oxide production and artery relaxation. Flow‐activated release of ACh from the endothelium is non‐vesicular and occurs via organic cation transporters. ACh is generated following mitochondrial production of acetylCoA. Thus, we show ACh is an autocrine signalling molecule released from endothelial cells, and identify a new role for the classical neurotransmitter in endothelial mechanotransduction. PMID:27730645

Design of a Tool Integrating Force Sensing With Automated Insertion in Cochlear Implantation

PubMed Central

Schurzig, Daniel; Labadie, Robert F.; Hussong, Andreas; Rau, Thomas S.; Webster, Robert J.

2012-01-01

The quality of hearing restored to a deaf patient by a cochlear implant in hearing preservation cochlear implant surgery (and possibly also in routine cochlear implant surgery) is believed to depend on preserving delicate cochlear membranes while accurately inserting an electrode array deep into the spiral cochlea. Membrane rupture forces, and possibly, other indicators of suboptimal placement, are below the threshold detectable by human hands, motivating a force sensing insertion tool. Furthermore, recent studies have shown significant variability in manual insertion forces and velocities that may explain some instances of imperfect placement. Toward addressing this, an automated insertion tool was recently developed by Hussong et al. By following the same insertion tool concept, in this paper, we present mechanical enhancements that improve the surgeon’s interface with the device and make it smaller and lighter. We also present electomechanical design of new components enabling integrated force sensing. The tool is designed to be sufficiently compact and light that it can be mounted to a microstereotactic frame for accurate image-guided preinsertion positioning. The new integrated force sensing system is capable of resolving forces as small as 0.005 N, and we provide experimental illustration of using forces to detect errors in electrode insertion. PMID:23482414

Quartz crystal microbalance as a sensing active element for rupture scanning within frequency band.

PubMed

Dultsev, F N; Kolosovsky, E A

2011-02-14

A new method based on the use of quartz crystal microbalance (QCM) as an active sensing element is developed, optimized and tested in a model system to measure the rupture force and deduce size distribution of nanoparticles. As suggested by model predictions, the QCM is shaped as a strip. The ratio of rupture signals at the second and the third harmonics versus the geometric position of a body on QCM surface is investigated theoretically. Recommendations concerning the use of the method for measuring the nanoparticle size distribution are presented. It is shown experimentally for an ensemble of test particles with a characteristic size within 20-30 nm that the proposed method allows one to determine particle size distribution. On the basis of the position and value of the measured rupture signal, a histogram of particle size distribution and percentage of each size fraction were determined. The main merits of the bond-rupture method are its rapid response, simplicity and the ability to discriminate between specific and non-specific interactions. The method is highly sensitive with respect to mass (the sensitivity is generally dependent on the chemical nature of receptor and analyte and may reach 8×10(-14) g mm(-2)) and applicable to measuring rupture forces either for weak bonds, for example hydrogen bonds, or for strong covalent bonds (10(-11)-10(-9) N). This procedure may become a good alternative for the existing methods, such as AFM or optical methods of determining biological objects, and win a broad range of applications both in laboratory research and in biosensing for various purposes. Possible applications include medicine, diagnostics, environmental or agricultural monitoring. Copyright © 2010 Elsevier B.V. All rights reserved.

The Enhanced Formaldehyde-Sensing Properties of P3HT-ZnO Hybrid Thin Film OTFT Sensor and Further Insight into Its Stability

PubMed Central

Tai, Huiling; Li, Xian; Jiang, Yadong; Xie, Guangzhong; Du, Xiaosong

2015-01-01

A thin-film transistor (TFT) having an organic–inorganic hybrid thin film combines the advantage of TFT sensors and the enhanced sensing performance of hybrid materials. In this work, poly(3-hexylthiophene) (P3HT)-zinc oxide (ZnO) nanoparticles' hybrid thin film was fabricated by a spraying process as the active layer of TFT for the employment of a room temperature operated formaldehyde (HCHO) gas sensor. The effects of ZnO nanoparticles on morphological and compositional features, electronic and HCHO-sensing properties of P3HT-ZnO thin film were systematically investigated. The results showed that P3HT-ZnO hybrid thin film sensor exhibited considerable improvement of sensing response (more than two times) and reversibility compared to the pristine P3HT film sensor. An accumulation p-n heterojunction mechanism model was developed to understand the mechanism of enhanced sensing properties by incorporation of ZnO nanoparticles. X-ray photoelectron spectroscope (XPS) and atomic force microscopy (AFM) characterizations were used to investigate the stability of the sensor in-depth, which reveals the performance deterioration was due to the changes of element composition and the chemical state of hybrid thin film surface induced by light and oxygen. Our study demonstrated that P3HT-ZnO hybrid thin film TFT sensor is beneficial in the advancement of novel room temperature HCHO sensing technology. PMID:25608214

The enhanced formaldehyde-sensing properties of P3HT-ZnO hybrid thin film OTFT sensor and further insight into its stability.

PubMed

Tai, Huiling; Li, Xian; Jiang, Yadong; Xie, Guangzhong; Du, Xiaosong

2015-01-19

A thin-film transistor (TFT) having an organic-inorganic hybrid thin film combines the advantage of TFT sensors and the enhanced sensing performance of hybrid materials. In this work, poly(3-hexylthiophene) (P3HT)-zinc oxide (ZnO) nanoparticles' hybrid thin film was fabricated by a spraying process as the active layer of TFT for the employment of a room temperature operated formaldehyde (HCHO) gas sensor. The effects of ZnO nanoparticles on morphological and compositional features, electronic and HCHO-sensing properties of P3HT-ZnO thin film were systematically investigated. The results showed that P3HT-ZnO hybrid thin film sensor exhibited considerable improvement of sensing response (more than two times) and reversibility compared to the pristine P3HT film sensor. An accumulation p-n heterojunction mechanism model was developed to understand the mechanism of enhanced sensing properties by incorporation of ZnO nanoparticles. X-ray photoelectron spectroscope (XPS) and atomic force microscopy (AFM) characterizations were used to investigate the stability of the sensor in-depth, which reveals the performance deterioration was due to the changes of element composition and the chemical state of hybrid thin film surface induced by light and oxygen. Our study demonstrated that P3HT-ZnO hybrid thin film TFT sensor is beneficial in the advancement of novel room temperature HCHO sensing technology.

Force Sensing Applications of DNA Origami Nanodevices

NASA Astrophysics Data System (ADS)

Hudoba, Michael William

Mechanical forces in biological systems vary in both length and magnitude by orders of magnitude making them difficult to probe and characterize with existing experimental methodologies. From molecules to cells, forces can act across length scales of nanometers to microns at magnitudes ranging from picoNewtons to nanoNewtons. Although single-molecule techniques such as optical traps, magnetic tweezers, and atomic force microscopy have improved the resolution and sensitivity of such measurements, inherent drawbacks exist in their capabilities due to the nature of the tools themselves. Specifically, these techniques have limitations in their ability to measure forces in realistic cellular environments and are not amenable to in vivo applications or measurements in mimicked physiological environments. In this thesis, we present a method to develop DNA force-sensing nanodevices with sub-picoNewton resolution capable of measuring forces in realistic cellular environments, with future applications in vivo. We use a design technique known as DNA origami to assemble devices with nanoscale geometric precision through molecular self-assembly via Watson-Crick base pairing. The devices have multiple conformational states, monitored by observing a Forster Resonance Energy Transfer signal that can change under the application of force. We expanded this study by demonstrating the design of responsive structural dynamics in DNA-based nanodevices. While prior studies have relied on external inputs to drive relatively slow dynamics in DNA nanostructures, here we developed DNA nanodevices with thermally driven dynamic function. The device was designed with an ensemble of conformations, and we establish methods to tune the equilibrium distribution of conformations and the rate of switching between states. We also show this nanodynamic behavior is responsive to physical interactions with the environment by measuring molecular crowding forces in the sub-picoNewton range, which are known to play a critical role in regulating molecular interactions and processes. Broadly, this work establishes a foundation for nanodevices with thermally driven dynamics that enable new measurement and control functions. We also examine the effect that forces have on the mechanical properties of DNA origami devices by developing a method to automate mesh generation for Finite Element Analysis. With this approach we are able to determine how defects that arise during assembly affect mechanical strain within structures during force application that can ultimately lead to device failure.

Force-Sensing Enhanced Simulation Environment (ForSense) for laparoscopic surgery training and assessment.

PubMed

Cundy, Thomas P; Thangaraj, Evelyn; Rafii-Tari, Hedyeh; Payne, Christopher J; Azzie, Georges; Sodergren, Mikael H; Yang, Guang-Zhong; Darzi, Ara

2015-04-01

Excessive or inappropriate tissue interaction force during laparoscopic surgery is a recognized contributor to surgical error, especially for robotic surgery. Measurement of force at the tool-tissue interface is, therefore, a clinically relevant skill assessment variable that may improve effectiveness of surgical simulation. Popular box trainer simulators lack the necessary technology to measure force. The aim of this study was to develop a force sensing unit that may be integrated easily with existing box trainer simulators and to (1) validate multiple force variables as objective measurements of laparoscopic skill, and (2) determine concurrent validity of a revised scoring metric. A base plate unit sensitized to a force transducer was retrofitted to a box trainer. Participants of 3 different levels of operative experience performed 5 repetitions of a peg transfer and suture task. Multiple outcome variables of force were assessed as well as a revised scoring metric that incorporated a penalty for force error. Mean, maximum, and overall magnitudes of force were significantly different among the 3 levels of experience, as well as force error. Experts were found to exert the least force and fastest task completion times, and vice versa for novices. Overall magnitude of force was the variable most correlated with experience level and task completion time. The revised scoring metric had similar predictive strength for experience level compared with the standard scoring metric. Current box trainer simulators can be adapted for enhanced objective measurements of skill involving force sensing. These outcomes are significantly influenced by level of expertise and are relevant to operative safety in laparoscopic surgery. Conventional proficiency standards that focus predominantly on task completion time may be integrated with force-based outcomes to be more accurately reflective of skill quality. Copyright © 2015 Elsevier Inc. All rights reserved.

The Use of Remote Sensing to Resolve the Aerosol Radiative Forcing

NASA Technical Reports Server (NTRS)

Kaufman, Y. J.; Tanre, D.; Remer, Lorraine

1999-01-01

Satellites are used for remote sensing of aerosol optical thickness and optical properties in order to derive the aerosol direct and indirect radiative forcing of climate. Accuracy of the derived aerosol optical thickness is used as a measure of the accuracy in deriving the aerosol radiative forcing. Several questions can be asked to challenge this concept. Is the accuracy of the satellite-derived aerosol direct forcing limited to the accuracy of the measured optical thickness? What are the spectral bands needed to derive the total aerosol forcing? Does most of the direct or indirect aerosol forcing of climate originate from regions with aerosol concentrations that are high enough to be detected from space? What should be the synergism ground-based and space-borne remote sensing to solve the problem? We shall try to answer some of these questions, using AVIRIS airborne measurements and simulations.

Silicon force sensor

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

Galambos, Paul C.; Crenshaw, Thomas B.; Nishida, Erik E.

The various technologies presented herein relate to a sensor for measurement of high forces and/or high load shock rate(s), whereby the sensor utilizes silicon as the sensing element. A plate of Si can have a thinned region formed therein on which can be formed a number of traces operating as a Wheatstone bridge. The brittle Si can be incorporated into a layered structure comprising ductile and/or compliant materials. The sensor can have a washer-like configuration which can be incorporated into a nut and bolt configuration, whereby tightening of the nut and bolt can facilitate application of a compressive preload uponmore » the sensor. Upon application of an impact load on the bolt, the compressive load on the sensor can be reduced (e.g., moves towards zero-load), however the magnitude of the preload can be such that the load on the sensor does not translate to tensile stress being applied to the sensor.« less

Force sensing by the vascular protein von Willebrand factor is tuned by a strong intermonomer interaction

PubMed Central

Müller, Jochen P.; Mielke, Salomé; Löf, Achim; Obser, Tobias; Beer, Christof; Bruetzel, Linda K.; Pippig, Diana A.; Vanderlinden, Willem; Lipfert, Jan; Schneppenheim, Reinhard; Benoit, Martin

2016-01-01

The large plasma glycoprotein von Willebrand factor (VWF) senses hydrodynamic forces in the bloodstream and responds to elevated forces with abrupt elongation, thereby increasing its adhesiveness to platelets and collagen. Remarkably, forces on VWF are elevated at sites of vascular injury, where VWF’s hemostatic potential is important to mediate platelet aggregation and to recruit platelets to the subendothelial layer. Adversely, elevated forces in stenosed vessels lead to an increased risk of VWF-mediated thrombosis. To dissect the remarkable force-sensing ability of VWF, we have performed atomic force microscopy (AFM)-based single-molecule force measurements on dimers, the smallest repeating subunits of VWF multimers. We have identified a strong intermonomer interaction that involves the D4 domain and critically depends on the presence of divalent ions, consistent with results from small-angle X-ray scattering (SAXS). Dissociation of this strong interaction occurred at forces above ∼50 pN and provided ∼80 nm of additional length to the elongation of dimers. Corroborated by the static conformation of VWF, visualized by AFM imaging, we estimate that in VWF multimers approximately one-half of the constituent dimers are firmly closed via the strong intermonomer interaction. As firmly closed dimers markedly shorten VWF’s effective length contributing to force sensing, they can be expected to tune VWF’s sensitivity to hydrodynamic flow in the blood and to thereby significantly affect VWF’s function in hemostasis and thrombosis. PMID:26787887

Accuracy of gastrocnemius muscles forces in walking and running goats predicted by one-element and two-element Hill-type models.

PubMed

Lee, Sabrina S M; Arnold, Allison S; Miara, Maria de Boef; Biewener, Andrew A; Wakeling, James M

2013-09-03

Hill-type models are commonly used to estimate muscle forces during human and animal movement-yet the accuracy of the forces estimated during walking, running, and other tasks remains largely unknown. Further, most Hill-type models assume a single contractile element, despite evidence that faster and slower motor units, which have different activation-deactivation dynamics, may be independently or collectively excited. This study evaluated a novel, two-element Hill-type model with "differential" activation of fast and slow contractile elements. Model performance was assessed using a comprehensive data set (including measures of EMG intensity, fascicle length, and tendon force) collected from the gastrocnemius muscles of goats during locomotor experiments. Muscle forces predicted by the new two-element model were compared to the forces estimated using traditional one-element models and to the forces measured in vivo using tendon buckle transducers. Overall, the two-element model resulted in the best predictions of in vivo gastrocnemius force. The coefficient of determination, r(2), was up to 26.9% higher and the root mean square error, RMSE, was up to 37.4% lower for the two-element model than for the one-element models tested. All models captured salient features of the measured muscle force during walking, trotting, and galloping (r(2)=0.26-0.51), and all exhibited some errors (RMSE=9.63-32.2% of the maximum in vivo force). These comparisons provide important insight into the accuracy of Hill-type models. The results also show that incorporation of fast and slow contractile elements within muscle models can improve estimates of time-varying, whole muscle force during locomotor tasks. Copyright © 2013 Elsevier Ltd. All rights reserved.

Accuracy of gastrocnemius muscles forces in walking and running goats predicted by one-element and two-element Hill-type models

PubMed Central

Lee, Sabrina S.M.; Arnold, Allison S.; Miara, Maria de Boef; Biewener, Andrew A.; Wakeling, James M.

2013-01-01

Hill-type models are commonly used to estimate muscle forces during human and animal movement —yet the accuracy of the forces estimated during walking, running, and other tasks remains largely unknown. Further, most Hill-type models assume a single contractile element, despite evidence that faster and slower motor units, which have different activation-deactivation dynamics, may be independently or collectively excited. This study evaluated a novel, two-element Hill-type model with “differential” activation of fast and slow contractile elements. Model performance was assessed using a comprehensive data set (including measures of EMG intensity, fascicle length, and tendon force) collected from the gastrocnemius muscles of goats during locomotor experiments. Muscle forces predicted by the new two-element model were compared to the forces estimated using traditional one-element models and to the forces measured in vivo using tendon buckle transducers. Overall, the two-element model resulted in the best predictions of in vivo gastrocnemius force. The coefficient of determination, r2, was up to 26.9% higher and the root mean square error, RMSE, was up to 37.4% lower for the two-element model than for the one-element models tested. All models captured salient features of the measured muscle force during walking, trotting, and galloping (r2 = 0.26 to 0.51), and all exhibited some errors (RMSE = 9.63 to 32.2% of the maximum in vivo force). These comparisons provide important insight into the accuracy of Hill-type models. The results also show that incorporation of fast and slow contractile elements within muscle models can improve estimates of time-varying, whole muscle force during locomotor tasks. PMID:23871235

Towards ultrasound enhanced mid-IR spectroscopy for sensing bacteria in aqueous solutions

NASA Astrophysics Data System (ADS)

Freitag, Stephan; Schwaighofer, Andreas; Radel, Stefan; Lendl, Bernhard

2018-02-01

We employ attenuated total reflection (ATR) mid-IR technology for sensing of bacteria present in aqueous solution. In ATR spectroscopy, the penetration depth of the evanescent field extends to approx. 1-2 micrometers into the aqueous solution depending on the refractive index of the employed materials (Si, ZnS, Ge) used as attenuated total reflection (ATR) element and the geometry of the optical set-up. Due to the flow profile in the microfluidic cell, an additional force is required to bring particles into the evanescent field for measurement. For that purpose, we employ standing ultrasound waves produced between a sound source vibrating at approx. 2 MHz and the ATR crystal acting as a reflector. This ultrasonic trap is integrated into the microfluidic channel. As aqueous solution is passing through that acoustofluidic cell, particles are concentrated in the nodal plane of the standing ultrasound wave, forming particle conglomerates. By selecting appropriate experimental conditions, it is then possible to press bacteria against the crystal surface for interaction with the evanescent wave (as well as to keep them away from the ATR element). Our current work aims at establishing a custommade US-ATR-IR setup for signal enhancement of bacteria (e.g. E. coli, P. aeruginosa as well as Salmonella) in drinking water.

Fabrication and optical characterization of imaging fiber-based nanoarrays.

PubMed

Tam, Jenny M; Song, Linan; Walt, David R

2005-09-15

In this paper, we present a technique for fabricating arrays containing a density at least 90 times higher than previously published. Specifically, we discuss the fabrication of two imaging fiber-based nanoarrays, one with 700nm features, another with 300nm features. With arrays containing up to 4.5x10(6) array elements/mm(2), these nanoarrays have an ultra-high packing density. A straightforward etching protocol is used to create nanowells into which beads can be deposited. These beads comprise the sensing elements of the nanoarray. Deposition of the nanobeads into the nanowells using two techniques is described. The surface characteristics of the etched arrays are examined with atomic force microscopy and scanning electron microscopy. Fluorescence microscopy was used to observe the arrays. The 300nm array features and the 500nm center-to-center distance approach the minimum feature sizes viewable using conventional light microscopy.

Periodical Microstructures Based on Novel Piezoelectric Material for Biomedical Applications.

PubMed

Janusas, Giedrius; Ponelyte, Sigita; Brunius, Alfredas; Guobiene, Asta; Prosycevas, Igoris; Vilkauskas, Andrius; Palevicius, Arvydas

2015-12-15

A novel cantilever type piezoelectric sensing element was developed. Cost-effective and simple fabrication design allows the use of this element for various applications in the areas of biomedicine, pharmacy, environmental analysis and biosensing. This paper proposes a novel piezoelectric composite material whose basic element is PZT and a sensing platform where this material was integrated. Results showed that a designed novel cantilever-type element is able to generate a voltage of up to 80 µV at 50 Hz frequency. To use this element for sensing purposes, a four micron periodical microstructure was imprinted. Silver nanoparticles were precipitated on the grating to increase the sensitivity of the designed element, i.e., Surface Plasmon Resonance (SPR) effect appears in the element. To tackle some issues (a lack of sensitivity, signal delays) the element must have certain electronic and optical properties. One possible solution, proposed in this paper, is a combination of piezoelectricity and SPR in a single element.

Role of Contact Force Sensing in Catheter Ablation of Cardiac Arrhythmias: Evolution or History Repeating Itself?

PubMed

Ariyarathna, Nilshan; Kumar, Saurabh; Thomas, Stuart P; Stevenson, William G; Michaud, Gregory F

2018-06-01

Adequate catheter-tissue contact facilitates efficient heat energy transfer to target tissue. Tissue contact is thus critical to achieving lesion transmurality and success of radiofrequency (RF) ablation procedures, a fact recognized more than 2 decades ago. The availability of real-time contact force (CF)-sensing catheters has reinvigorated the field of ablation biophysics and optimized lesion formation. The ability to measure and display CF came with the promise of dramatic improvement in safety and efficacy; however, CF quality was noted to have just as important an influence on lesion formation as absolute CF quantity. Multiple other factors have emerged as key elements influencing effective lesion formation, including catheter stability, lesion contiguity and continuity, lesion density, contact homogeneity across a line of ablation, spatiotemporal dynamics of contact governed by cardiac and respiratory motion, contact directionality, and anatomic wall thickness, in addition to traditional ablation indices of power and RF duration. There is greater appreciation of surrogate markers as a guide to lesion formation, such as impedance fall, loss of pace capture, and change in unipolar electrogram morphology. In contrast, other surrogates such as tactile feedback, catheter motion, and electrogram amplitude are notably poor predictors of actual contact and lesion formation. This review aims to contextualize the role of CF sensing in lesion formation with respect of the fundamental principles of biophysics of RF ablation and summarize the state-of-the-art evidence behind the role of CF in optimizing lesion formation. Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

New measuring system for the distribution of a magnetic force by using an optical fiber

NASA Astrophysics Data System (ADS)

Ishigaki, H.; Oya, T.; Itoh, M.; Hida, A.; Iwata, K.

1993-01-01

A new measuring system using an optical fiber and a position sensing photodetector was developed to measure a three-dimensional distribution of a magnetic force. A steel ball attached to a cantilever made of an optical fiber generated force in a magnetic field. The displacement of the ball due to the force was detected by a position-sensing photodetector with the capability of detecting two-directional coordinates of the position. By scanning the sensing system in a magnetic field, we obtained distributions of two-directional component of the magnetic force vector. The component represents the gradient of a squared magnetic field. The usefulness of the system for measuring the magnetic field distribution in a narrow clearance and for evaluating superconducting machine components such as magnetic bearings was verified experimentally.

A clamping force measurement system for monitoring the condition of bolted joints on railway track joints and points

NASA Astrophysics Data System (ADS)

Tesfa, B.; Horler, G.; Thobiani, F. Al; Gu, F.; Ball, A. D.

2012-05-01

Many industrial structures associated with railway infrastructures rely on a large number of bolted joint connections to ensure safe and reliable operation of the track and trackside furniture. Significant sums of money are spent annually to repair the damage caused by bolt failures and to maintain the integrity of bolted structures. In the UK, Network Rail (the organization responsible for rail network maintenance and safety) conducts corrective and preventive maintenance manually on 26,000 sets of points (each having approximately 30 bolted joints per set), in order to ensure operational success and safety for the travelling public. Such manual maintenance is costly, disruptive, unreliable and prone to human error. The aim of this work is to provide a means of automatically measuring the clamping force of each individual bolted joint, by means of an instrumented washer. This paper describes the development of a sensor means to be used in the washer, which satisfies the following criteria. Sense changes in the clamping force of the joint and report this fact. Provide compatibility with the large dynamic range of clamping force. Satisfy the limitations in terms of physical size. Provide the means to electronically interface with the washer. Provide a means of powering the washer in situ. Provide a solution at an acceptable cost. Specifically the paper focuses on requirements 1, 2 and 3 and presents the results that support further development of the proposed design and the realization of a pre-prototype system. In the paper, various options for the force sensing element (strain gage, capacitor, piezo-resistive) have been compared, using design optimization techniques. As a result of the evaluation, piezo-resistive sensors in concert with a proprietary force attenuation method, have been found to offer the best performance and cost trade-off The performance of the novel clamping force sensor has been evaluated experimentally and the results show that a smart washer can be developed to monitor the condition of bolted joints as found on railway track and points.

Flexible Framework for Capacitive Sensing

NASA Technical Reports Server (NTRS)

Woodard, Stanley E. (Inventor); Taylor, Bryant D. (Inventor)

2006-01-01

A flexible framework supports electrically-conductive elements in a capacitive sensing arrangement. Identical frames are arranged end-to-end with adjacent frames being capable of rotational movement there between. Each frame has first and second passages extending therethrough and parallel to one another. Each of the first and second passages is adapted to receive an electrically-conductive element therethrough. Each frame further has a hollowed-out portion for the passage of a fluent material therethrough. The hollowed-out portion is sized and shaped to provide for capacitive sensing along a defined region between the electrically-conductive element in the first passage and the electrically-conductive element in the second passage.

Displacement sensor containing magnetic field sensing element between a pair of biased magnets movable as a unit

NASA Technical Reports Server (NTRS)

Bahr, Joseph K. (Inventor); Johnson, Mont A. (Inventor)

2003-01-01

A displacement sensor for providing an indication of the position of a first body relative to a second body, the first body being displaceable relative to the second body in a displacement direction. The sensor is composed of: two magnets that are spaced from one another in the displacement direction to define therebetween a region containing a magnetic field; a magnetic field sensing element mounted in the region; and components for coupling at least one of the magnets to one of the bodies and the magnetic field sensing element to the other of the bodies to produce a relative displacement between the at least one magnet and the magnetic field sensing element in the displacement direction in response to displacement of the first body relative to the second body.

An approach to improve the spatial resolution of a force mapping sensing system

NASA Astrophysics Data System (ADS)

Negri, Lucas Hermann; Manfron Schiefer, Elberth; Sade Paterno, Aleksander; Muller, Marcia; Luís Fabris, José

2016-02-01

This paper proposes a smart sensor system capable of detecting sparse forces applied to different positions of a metal plate. The sensing is performed with strain transducers based on fiber Bragg gratings (FBG) distributed under the plate. Forces actuating in nine squared regions of the plate, resulting from up to three different loads applied simultaneously to the plate, were monitored with seven transducers. The system determines the magnitude of the force/pressure applied on each specific area, even in the absence of a dedicated transducer for that area. The set of strain transducers with coupled responses and a compressive sensing algorithm are employed to solve the underdetermined inverse problem which emerges from mapping the force. In this configuration, experimental results have shown that the system is capable of recovering the value of the load distributed on the plate with a signal-to-noise ratio better than 12 dB, when the plate is submitted to three simultaneous test loads. The proposed method is a practical illustration of compressive sensing algorithms for the reduction of the number of FBG-based transducers used in a quasi-distributed configuration.

Hypersonic force measurements using internal balance based on optical micromachined Fabry-Perot interferometry.

PubMed

Qiu, Huacheng; Min, Fu; Zhong, Shaolong; Song, Xin; Yang, Yanguang

2018-03-01

Force measurements using wind tunnel balance are necessary for determining a variety of aerodynamic performance parameters, while the harsh environment in hypersonic flows requires that the measurement instrument should be reliable and robust, in against strong electromagnetic interference, high vacuum, or metal (oxide) dusts. In this paper, we demonstrated a three-component internal balance for hypersonic aerodynamic force measurements, using novel optical micromachined Fabry-Perot interferometric (FPI) strain gauges as sensing elements. The FPI gauges were fabricated using Micro-Opto-Electro-Mechanical Systems (MOEMS) surface and bulk fabrication techniques. High-reflectivity coatings are used to form a high-finesse Fabry-Perot cavity, which benefits a high resolution. Antireflective and passivation coatings are used to reduce unwanted interferences. The FPI strain gauge based balance has been calibrated and evaluated in a Mach 5 hypersonic flow. The results are compared with the traditional technique using the foil resistive strain gauge balance, indicating that the proposed balance based on the MOEMS FPI strain gauge is reliable and robust and is potentially suitable for the hypersonic wind tunnel harsh environment.

Hypersonic force measurements using internal balance based on optical micromachined Fabry-Perot interferometry

NASA Astrophysics Data System (ADS)

Qiu, Huacheng; Min, Fu; Zhong, Shaolong; Song, Xin; Yang, Yanguang

2018-03-01

Force measurements using wind tunnel balance are necessary for determining a variety of aerodynamic performance parameters, while the harsh environment in hypersonic flows requires that the measurement instrument should be reliable and robust, in against strong electromagnetic interference, high vacuum, or metal (oxide) dusts. In this paper, we demonstrated a three-component internal balance for hypersonic aerodynamic force measurements, using novel optical micromachined Fabry-Perot interferometric (FPI) strain gauges as sensing elements. The FPI gauges were fabricated using Micro-Opto-Electro-Mechanical Systems (MOEMS) surface and bulk fabrication techniques. High-reflectivity coatings are used to form a high-finesse Fabry-Perot cavity, which benefits a high resolution. Antireflective and passivation coatings are used to reduce unwanted interferences. The FPI strain gauge based balance has been calibrated and evaluated in a Mach 5 hypersonic flow. The results are compared with the traditional technique using the foil resistive strain gauge balance, indicating that the proposed balance based on the MOEMS FPI strain gauge is reliable and robust and is potentially suitable for the hypersonic wind tunnel harsh environment.

Three tenets for secure cyber-physical system design and assessment

NASA Astrophysics Data System (ADS)

Hughes, Jeff; Cybenko, George

2014-06-01

This paper presents a threat-driven quantitative mathematical framework for secure cyber-physical system design and assessment. Called The Three Tenets, this originally empirical approach has been used by the US Air Force Research Laboratory (AFRL) for secure system research and development. The Tenets were first documented in 2005 as a teachable methodology. The Tenets are motivated by a system threat model that itself consists of three elements which must exist for successful attacks to occur: - system susceptibility; - threat accessibility and; - threat capability. The Three Tenets arise naturally by countering each threat element individually. Specifically, the tenets are: Tenet 1: Focus on What's Critical - systems should include only essential functions (to reduce susceptibility); Tenet 2: Move Key Assets Out-of-Band - make mission essential elements and security controls difficult for attackers to reach logically and physically (to reduce accessibility); Tenet 3: Detect, React, Adapt - confound the attacker by implementing sensing system elements with dynamic response technologies (to counteract the attackers' capabilities). As a design methodology, the Tenets mitigate reverse engineering and subsequent attacks on complex systems. Quantified by a Bayesian analysis and further justified by analytic properties of attack graph models, the Tenets suggest concrete cyber security metrics for system assessment.

Integration of a sensor based multiple robot environment for space applications: The Johnson Space Center Teleoperator Branch Robotics Laboratory

NASA Technical Reports Server (NTRS)

Hwang, James; Campbell, Perry; Ross, Mike; Price, Charles R.; Barron, Don

1989-01-01

An integrated operating environment was designed to incorporate three general purpose robots, sensors, and end effectors, including Force/Torque Sensors, Tactile Array sensors, Tactile force sensors, and Force-sensing grippers. The design and implementation of: (1) the teleoperation of a general purpose PUMA robot; (2) an integrated sensor hardware/software system; (3) the force-sensing gripper control; (4) the host computer system for dual Robotic Research arms; and (5) the Ethernet integration are described.

Sensing And Force-Reflecting Exoskeleton

NASA Technical Reports Server (NTRS)

Eberman, Brian; Fontana, Richard; Marcus, Beth

1993-01-01

Sensing and force-reflecting exoskeleton (SAFiRE) provides control signals to robot hand and force feedback from robot hand to human operator. Operator makes robot hand touch objects gently and manipulates them finely without exerting excessive forces. Device attaches to operator's hand; comfortable and lightweight. Includes finger exoskeleton, cable mechanical transmission, two dc servomotors, partial thumb exoskeleton, harness, amplifier box, two computer circuit boards, and software. Transduces motion of index finger and thumb. Video monitor of associated computer displays image corresponding to motion.

The Large Area Crop Inventory Experiment (LACIE). Part 3: A systematic approach to the practical application of remote-sensing technology

NASA Technical Reports Server (NTRS)

Murphy, J. D.; Dideriksen, R. I.

1975-01-01

The application of remote sensing technology by the U.S. Department of Agriculture (USDA) is examined. The activities of the USDA Remote-Sensing User Requirement Task Force which include cataloging USDA requirements for earth resources data, determining those requirements that would return maximum benefits by using remote sensing technology and developing a plan for acquiring, processing, analyzing, and distributing data to satisfy those requirements are described. Emphasis is placed on the large area crop inventory experiment and its relationship to the task force.

Mechanisms of Local Stress Sensing in Multifunctional Polymer Films Using Fluorescent Tetrapod Nanocrystals

DOE PAGES

Raja, Shilpa N.; Zherebetskyy, Danylo; Wu, Siva; ...

2016-07-13

Nanoscale stress-sensing can be used across fields ranging from detection of incipient cracks in structural mechanics to monitoring forces in biological tissues. We demonstrate how tetrapod quantum dots (tQDs) embedded in block copolymers act as sensors of tensile/compressive stress. Remarkably, tQDs can detect their own composite dispersion and mechanical properties with a switch in optomechanical response when tQDs are in direct contact. Using experimental characterizations, atomistic simulations and finite-element analyses, we show that under tensile stress, densely packed tQDs exhibit a photoluminescence peak shifted to higher energies ("blue-shift") due to volumetric compressive stress in their core; loosely packed tQDs exhibitmore » a peak shifted to lower energies ("red-shift") from tensile stress in the core. The stress shifts result from the tQD's unique branched morphology in which the CdS arms act as antennas that amplify the stress in the CdSe core. Our nanocomposites exhibit excellent cyclability and scalability with no degraded properties of the host polymer. Colloidal tQDs allow sensing in many materials to potentially enable autoresponsive, smart structural nanocomposites that self-predict upcoming fracture.« less

Three-axis force sensor with fiber Bragg grating.

PubMed

Hyundo Choi; Yoan Lim; Junhyung Kim

2017-07-01

Haptic feedback is critical for many surgical tasks, and it replicates force reflections at the surgical site. To meet the force reflection requirements, we propose a force sensor with an optical fiber Bragg grating (FBG) for robotic surgery. The force sensor can calculate three directional forces of an instrument from the strain of three FBGs, even under electromagnetic interference. A flexible ring-shape structure connects an instrument tip and fiber strain gages to sense three directional force. And a stopper mechanism is added in the structure to avoid plastic deformation under unexpected large force on the instrument tip. The proposed sensor is experimentally verified to have a sensing range from -12 N to 12 N, and its sensitivity was less than 0.06 N.

Force modeling for incision surgery into tissue with haptic application

NASA Astrophysics Data System (ADS)

Kim, Pyunghwa; Kim, Soomin; Choi, Seung-Hyun; Oh, Jong-Seok; Choi, Seung-Bok

2015-04-01

This paper presents a novel force modeling for an incision surgery into tissue and its haptic application for a surgeon. During the robot-assisted incision surgery, it is highly urgent to develop the haptic system for realizing sense of touch in the surgical area because surgeons cannot sense sensations. To achieve this goal, the force modeling related to reaction force of biological tissue is proposed in the perspective on energy. The force model describes reaction force focused on the elastic feature of tissue during the incision surgery. Furthermore, the force is realized using calculated information from the model by haptic device using magnetorheological fluid (MRF). The performance of realized force that is controlled by PID controller with open loop control is evaluated.

Active noise control using noise source having adaptive resonant frequency tuning through stiffness variation

NASA Technical Reports Server (NTRS)

Rajiyah, Harindra (Inventor); Hedeen, Robert A. (Inventor); Pla, Frederic G. (Inventor); Renshaw, Anthony A. (Inventor)

1995-01-01

A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of a noise radiating element is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating element is tuned by a plurality of force transmitting mechanisms which contact the noise radiating element. Each one of the force transmitting mechanisms includes an expandable element and a spring in contact with the noise radiating element so that excitation of the element varies the spring force applied to the noise radiating element. The elements are actuated by a controller which receives input of a signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the elements and causes the spring force applied to the noise radiating element to be varied. The force transmitting mechanisms can be arranged to either produce bending or linear stiffness variations in the noise radiating element.

Force loading explains spatial sensing of ligands by cells

NASA Astrophysics Data System (ADS)

Oria, Roger; Wiegand, Tina; Escribano, Jorge; Elosegui-Artola, Alberto; Uriarte, Juan Jose; Moreno-Pulido, Cristian; Platzman, Ilia; Delcanale, Pietro; Albertazzi, Lorenzo; Navajas, Daniel; Trepat, Xavier; García-Aznar, José Manuel; Cavalcanti-Adam, Elisabetta Ada; Roca-Cusachs, Pere

2017-12-01

Cells can sense the density and distribution of extracellular matrix (ECM) molecules by means of individual integrin proteins and larger, integrin-containing adhesion complexes within the cell membrane. This spatial sensing drives cellular activity in a variety of normal and pathological contexts. Previous studies of cells on rigid glass surfaces have shown that spatial sensing of ECM ligands takes place at the nanometre scale, with integrin clustering and subsequent formation of focal adhesions impaired when single integrin-ligand bonds are separated by more than a few tens of nanometres. It has thus been suggested that a crosslinking ‘adaptor’ protein of this size might connect integrins to the actin cytoskeleton, acting as a molecular ruler that senses ligand spacing directly. Here, we develop gels whose rigidity and nanometre-scale distribution of ECM ligands can be controlled and altered. We find that increasing the spacing between ligands promotes the growth of focal adhesions on low-rigidity substrates, but leads to adhesion collapse on more-rigid substrates. Furthermore, disordering the ligand distribution drastically increases adhesion growth, but reduces the rigidity threshold for adhesion collapse. The growth and collapse of focal adhesions are mirrored by, respectively, the nuclear or cytosolic localization of the transcriptional regulator protein YAP. We explain these findings not through direct sensing of ligand spacing, but by using an expanded computational molecular-clutch model, in which individual integrin-ECM bonds—the molecular clutches—respond to force loading by recruiting extra integrins, up to a maximum value. This generates more clutches, redistributing the overall force among them, and reducing the force loading per clutch. At high rigidity and high ligand spacing, maximum recruitment is reached, preventing further force redistribution and leading to adhesion collapse. Measurements of cellular traction forces and actin flow speeds support our model. Our results provide a general framework for how cells sense spatial and physical information at the nanoscale, precisely tuning the range of conditions at which they form adhesions and activate transcriptional regulation.

The Acute Effect of Cryotherapy on Muscle Strength and Shoulder Proprioception.

PubMed

Torres, Rui; Silva, Filipa; Pedrosa, Vera; Ferreira, João; Lopes, Alexandre

2017-11-01

Cryotherapy, a common intervention used by clinicians, poses several benefits in managing acute injuries. However, cooling muscle tissue can interfere with muscular properties and the sensory-motor system. The aim of this study was to analyze the influence of cryotherapy with a crushed-ice pack on shoulder proprioception concerning joint position sense, force sense, the threshold for detecting passive movement, and maximal force production. A randomized, double-blind controlled trial. 48 healthy women aged 22.6 ± 0.4 y with a mean body mass index of 22.8 ±0.37 kg/m2 and a percentage of body fat of 15.4 ± 1.5%. In the experimental group, a crushed-ice pack was applied to the shoulder for 15 min, whereas participants in the control group applied a sandbag at skin temperature, also for 15 min. An isokinetic dynamometer was used to assess maximal voluntary contraction, force sense, joint position sense, and the threshold for detecting passive movement. Paired sample t tests revealed that maximal voluntary isometric contraction decreased significantly after cryotherapy (P ≤ .001), or approximately 10% of the reduction found in both muscular groups assessed. Shoulder position sense (P < .001) and the threshold for detecting passive movement (P = .01 and P = .01 for lateral and medial shoulder rotator muscles, respectively) also suffered significant impairment. Nevertheless, no significant differences emerged in force sense at 20% and 50% of maximal force reproduction (P = .41 and P = .10 for lateral rotator muscles at 20% and 50%, respectively; and P = .20 and P = .09 for medial rotator muscles at 20% and 50%, respectively). Applying a crushed-ice pack to the shoulder for 15 min negatively affected muscle strength and impaired shoulder proprioception by decreasing joint position sense and the threshold for detecting passive movement.

A New MEMS Gyroscope Used for Single-Channel Damping

PubMed Central

Zhang, Zengping; Zhang, Wei; Zhang, Fuxue; Wang, Biao

2015-01-01

The silicon micromechanical gyroscope, which will be introduced in this paper, represents a novel MEMS gyroscope concept. It is used for the damping of a single-channel control system of rotating aircraft. It differs from common MEMS gyroscopes in that does not have a drive structure, itself, and only has a sense structure. It is installed on a rotating aircraft, and utilizes the aircraft spin to make its sensing element obtain angular momentum. When the aircraft is subjected to an angular rotation, a periodic Coriolis force is induced in the direction orthogonal to both the angular momentum and the angular velocity input axis. This novel MEMS gyroscope can thus sense angular velocity inputs. The output sensing signal is exactly an amplitude-modulation signal. Its envelope is proportional to the input angular velocity, and the carrier frequency corresponds to the spin frequency of the rotating aircraft, so the MEMS gyroscope can not only sense the transverse angular rotation of an aircraft, but also automatically change the carrier frequency over the change of spin frequency, making it very suitable for the damping of a single-channel control system of a rotating aircraft. In this paper, the motion equation of the MEMS gyroscope has been derived. Then, an analysis has been carried to solve the motion equation and dynamic parameters. Finally, an experimental validation has been done based on a precision three axis rate table. The correlation coefficients between the tested data and the theoretical values are 0.9969, 0.9872 and 0.9842, respectively. These results demonstrate that both the design and sensing mechanism are correct. PMID:25942638

A Shape Memory Alloy Based Cryogenic Thermal Conduction Switch

NASA Technical Reports Server (NTRS)

Notardonato, W. U.; Krishnan, V. B.; Singh, J. D.; Woodruff, T. R.; Vaidyanathan, R.

2005-01-01

Shape memory alloys (SMAs) can produce large strains when deformed (e.g., up to 8%). Heating results in a phase transformation and associated recovery of all the accumulated strain. This strain recovery can occur against large forces, resulting in their use as actuators. Thus an SMA element can integrate both sensory and actuation functions, by inherently sensing a change in temperature and actuating by undergoing a shape change as a result of a temperature-induced phase transformation. Two aspects of our work on cryogenic SMAs are addressed here. First - a shape memory alloy based cryogenic thermal conduction switch for operation between dewars of liquid methane and liquid oxygen in a common bulkhead arrangement is discussed. Such a switch integrates the sensor element and the actuator element and can be used to create a variable thermal sink to other cryogenic tanks for liquefaction, densification, and zero boil-off systems for advanced spaceport applications. Second - fabrication via arc-melting and subsequent materials testing of SMAs with cryogenic transformation temperatures for use in the aforementioned switch is discussed.

Wavefront sensing and control aspects in a high energy laser optical train

NASA Astrophysics Data System (ADS)

Bartosewcz, M.; Bareket, N.

1981-01-01

In this paper we review the major elements of a HEL (high energy laser) wavefront sensing and control system with particular emphasis on experimental demonstrations and hardware components developed at Lockheed Missiles & Space Company, Inc. The review concentrates on three important elements of wavefront control: wavefront sampling, wavefront sensing and active mirrors. Methods of wavefront sampling by diffraction gratings are described. Some new developments in wavefront sensing are explored. Hardware development efforts of fast steering mirrors and edge controlled deformable mirrors are described.

Integrated dynamic and static tactile sensor: focus on static force sensing

NASA Astrophysics Data System (ADS)

Wettels, Nicholas; Pletner, Baruch

2012-04-01

Object grasping by robotic hands in unstructured environments demands a sensor that is durable, compliant, and responsive to static and dynamic force conditions. In order for a tactile sensor to be useful for grasp control in these, it should have the following properties: tri-axial force sensing (two shear plus normal component), dynamic event sensing across slip frequencies, compliant surface for grip, wide dynamic range (depending on application), insensitivity to environmental conditions, ability to withstand abuse and good sensing behavior (e.g. low hysteresis, high repeatability). These features can be combined in a novel multimodal tactile sensor. This sensor combines commercial-off-the-shelf MEMS technology with two proprietary force sensors: a high bandwidth device based on PZT technology and low bandwidth device based on elastomers and optics. In this study, we focus on the latter transduction mechanism and the proposed architecture of the completed device. In this study, an embedded LED was utilized to produce a constant light source throughout a layer of silicon rubber which covered a plastic mandrel containing a set of sensitive phototransistors. Features about the contacted object such as center of pressure and force vectors can be extracted from the information in the changing patterns of light. The voltage versus force relationship obtained with this molded humanlike finger had a wide dynamic range that coincided with forces relevant for most human grip tasks.

Fiber Bragg Grating based bite force measurement.

PubMed

Umesh, Sharath; Padma, Srivani; Asokan, Sundarrajan; Srinivas, Talabattula

2016-09-06

The present study reports an in vivo, novel methodology for the dynamic measurement of the bite force generated by individual tooth using a Fiber Bragg Grating Bite Force Recorder (FBGBFR). Bite force is considered as one of the major indicators of the functional state of the masticatory system, which is dependent on the craniomandibular structure comprising functional components such as muscles of mastication, joints and teeth. The proposed FBGBFR is an intra-oral device, developed for the transduction of the bite force exerted at the occlusal surface, into strain variations on a base plate, which in turn is sensed by the FBG sensor bonded over it. The FBGBFR is calibrated against a Micro Universal Testing Machine (UTM) for 0-900N range and the resolution of the developed FBGBFR is found to be 0.54N. 36 volunteers (20 males and 16 females) performed the bite force measurement test at molar, premolar and incisor tooth on either side of the dental arch and the obtained results show clinically relevant bite forces varying from 176N to 635N. The bite forces obtained from the current study for a substantial sample size, show that the bite forces increases along the dental arch from the incisors towards the molars and are found to be higher in male than in female. The FBG sensor element utilized in FBGBFR is electrically passive, which makes it a safe in vivo intra-oral device. Hence the FBGBFR is viable to be employed in clinical studies on biomechanics of oral function. Copyright © 2016 Elsevier Ltd. All rights reserved.

Conserved versatile master regulators in signalling pathways in response to stress in plants

PubMed Central

Balderas-Hernández, Victor E.; Alvarado-Rodríguez, Miguel; Fraire-Velázquez, Saúl

2013-01-01

From the first land plants to the complex gymnosperms and angiosperms of today, environmental conditions have forced plants to develop molecular strategies to surpass natural obstacles to growth and proliferation, and these genetic gains have been transmitted to the following generations. In this long natural process, novel and elaborate mechanisms have evolved to enable plants to cope with environmental limitations. Elements in many signalling cascades enable plants to sense different, multiple and simultaneous ambient cues. A group of versatile master regulators of gene expression control plant responses to stressing conditions. For crop breeding purposes, the task is to determine how to activate these key regulators to enable accurate and optimal reactions to common stresses. In this review, we discuss how plants sense biotic and abiotic stresses, how and which master regulators are implied in the responses to these stresses, their evolution in the life kingdoms, and the domains in these proteins that interact with other factors to lead to a proper and efficient plant response. PMID:24147216

Smart fabric sensors and e-textile technologies: a review

NASA Astrophysics Data System (ADS)

Castano, Lina M.; Flatau, Alison B.

2014-05-01

This paper provides a review of recent developments in the rapidly changing and advancing field of smart fabric sensor and electronic textile technologies. It summarizes the basic principles and approaches employed when building fabric sensors as well as the most commonly used materials and techniques used in electronic textiles. This paper shows that sensing functionality can be created by intrinsic and extrinsic modifications to textile substrates depending on the level of integration into the fabric platform. The current work demonstrates that fabric sensors can be tailored to measure force, pressure, chemicals, humidity and temperature variations. Materials, connectors, fabric circuits, interconnects, encapsulation and fabrication methods associated with fabric technologies prove to be customizable and versatile but less robust than their conventional electronics counterparts. The findings of this survey suggest that a complete smart fabric system is possible through the integration of the different types of textile based functional elements. This work intends to be a starting point for standardization of smart fabric sensing techniques and e-textile fabrication methods.

Contact sensing from force measurements

NASA Technical Reports Server (NTRS)

Bicchi, Antonio; Salisbury, J. K.; Brock, David L.

1993-01-01

This article addresses contact sensing (i.e., the problem of resolving the location of a contact, the force at the interface, and the moment about the contact normals). Called 'intrinsic' contact sensing for the use of internal force and torque measurements, this method allows for practical devices that provide simple, relevant contact information in practical robotic applications. Such sensors have been used in conjunction with robot hands to identify objects, determine surface friction, detect slip, augment grasp stability, measure object mass, probe surfaces, and control collision and for a variety of other useful tasks. This article describes the theoretical basis for their operation and provides a framework for future device design.

Evolution of Force Sensing Technologies.

PubMed

Shah, Dipen

2017-06-01

In order to Improve the procedural success and long-term outcomes of catheter ablation techniques for atrial fibrillation (AF), an Important unfulfilled requirement is to create durable electrophysiologically complete lesions. Measurement of contact force (CF) between the catheter tip and the target tissue can guide physicians to optimise both mapping and ablation procedures. Contact force can affect lesion size and clinical outcomes following catheter ablation of AF. Force sensing technologies have matured since their advent several years ago, and now allow the direct measurement of CF between the catheter tip and the target myocardium in real time. In order to obtain complete durable lesions, catheter tip spatial stability and stable contact force are important. Suboptimal energy delivery, lesion density/contiguity and/or excessive wall thickness of the pulmonary vein-left atrial (PV-LA) junction may result in conduction recovery at these sites. Lesion assessment tools may help predict and localise electrical weak points resulting in conduction recovery during and after ablation. There is increasing clinical evidence to show that optimal use of CF sensing during ablation can reduce acute PV re-conduction, although prospective randomised studies are desirable to confirm long-term favourable clinical outcomes. In combination with optimised lesion assessment tools, contact force sensing technology has the potential to become the standard of care for all patients undergoing AF catheter ablation.

Sensorization of a surgical robotic instrument for force sensing

NASA Astrophysics Data System (ADS)

Shahzada, Kaspar S.; Yurkewich, Aaron; Xu, Ran; Patel, Rajni V.

2016-03-01

This paper presents the development and application of an approach for sensorizing a surgical robotic instrument for two degree-of-freedom (DOF) lateral force sensing. The sensorized instrument is compatible with the da Vinci® Surgical System and can be used for skills assessment and force control in specific surgical tasks. The sensing technology utilizes a novel layout of four fiber Bragg grating (FBG) sensors attached to the shaft of a da Vinci® surgical instrument. The two cross-section layout is insensitive to error caused by combined force and torque loads, and the orientation of the sensors minimizes the condition number of the instrument's compliance matrix. To evaluate the instrument's sensing capabilities, its performance was tested using a commercially available force-torque sensor, and showed a resolution of 0.05N at 1 kHz sampling rate. The performance of the sensorized instrument was evaluated by performing three surgical tasks on phantom tissue using the da Vinci® system with the da Vinci Research Kit (dVRK): tissue palpation, knot tightening during suturing and Hem-O-Lok® tightening during knotless suturing. The tasks were designed to demonstrate the robustness of the sensorized force measurement approach. The paper reports the results of further evaluation by a group of expert and novice surgeons performing the three tasks mentioned above.

A Large Area Tactile Sensor Patch Based on Commercial Force Sensors

PubMed Central

Vidal-Verdú, Fernando; Barquero, Maria Jose; Castellanos-Ramos, Julián; Navas-González, Rafael; Sánchez, Jose Antonio; Serón, Javier; García-Cerezo, Alfonso

2011-01-01

This paper reports the design of a tactile sensor patch to cover large areas of robots and machines that interact with human beings. Many devices have been proposed to meet such a demand. These realizations are mostly custom-built or developed in the lab. The sensor of this paper is implemented with commercial force sensors. This has the benefit of a more foreseeable response of the sensor if its behavior is understood as the aggregation of readings from all the individual force sensors in the array. A few reported large area tactile sensors are also based on commercial sensors. However, the one in this paper is the first of this kind based on the use of polymeric commercial force sensing resistors (FSR) as unit elements of the array or tactels, which results in a robust sensor. The paper discusses design issues related to some necessary modifications of the force sensor, its assembly in an array, and the signal conditioning. The patch has 16 × 9 force sensors mounted on a flexible printed circuit board with a spatial resolution of 18.5 mm. The force range of a tactel is 6 N and its sensitivity is 0.6 V/N. The array is read at a rate of 78 frames per second. Finally, two simple application examples are also carried out with the sensor mounted on the forearm of a rescue robot that communicates with the sensor through a CAN bus. PMID:22163910

Development of CMOS MEMS inductive type tactile sensor with the integration of chrome steel ball force interface

NASA Astrophysics Data System (ADS)

Yeh, Sheng-Kai; Chang, Heng-Chung; Fang, Weileun

2018-04-01

This study presents an inductive tactile sensor with a chrome steel ball sensing interface based on the commercially available standard complementary metal-oxide-semiconductor (CMOS) process (the TSMC 0.18 µm 1P6M CMOS process). The tactile senor has a deformable polymer layer as the spring of the device and no fragile suspended thin film structures are required. As a tactile force is applied on the chrome steel ball, the polymer would deform. The distance between the chrome steel ball and the sensing coil would changed. Thus, the tactile force can be detected by the inductance change of the sensing coil. In short, the chrome steel ball acts as a tactile bump as well as the sensing interface. Experimental results show that the proposed inductive tactile sensor has a sensing range of 0-1.4 N with a sensitivity of 9.22(%/N) and nonlinearity of 2%. Preliminary wireless sensing test is also demonstrated. Moreover, the influence of the process and material issues on the sensor performances have also been investigated.

The Biomechanics of Cranial Forces During Figure Skating Spinning Elements.

PubMed

Wang, David H; Kostyun, Regina O; Solomito, Matthew J

2015-03-01

Several facets of figure skating, such as the forces associated with jumping and landing, have been evaluated, but a comprehensive biomechanical understanding of the cranial forces associated with spinning has yet to be explored. The purpose of this case study was to quantify the cranial rotational acceleration forces generated during spinning elements. This case report was an observational, biomechanical analysis of a healthy, senior-level, female figure skating athlete who is part of an on-going study. A triaxial accelerometer recorded the gravitational forces (G) during seven different spinning elements. Our results found that the layback spin generated significant cranial force and these forces were greater than any of the other spin elements recorded. These forces led to physical findings of ruptured capillaries, dizziness, and headaches in our participant.

High-Performance Flexible Force and Temperature Sensing Array with a Robust Structure

NASA Astrophysics Data System (ADS)

Kim, Min-Seok; Song, Han-Wook; Park, Yon-Kyu

We have developed a flexible tactile sensor array capable of sensing physical quantities, e.g. force and temperature with high-performances and high spatial resolution. The fabricated tactile sensor consists of 8 × 8 force measuring array with 1 mm spacing and a thin metal (copper) temperature sensor. The flexible force sensing array consists of sub-millimetre-size bar-shaped semi-conductor strain gage array attached to a thin and flexible printed circuit board covered by stretchable elastomeric material on both sides. This design incorporates benefits of both materials; the semi-conductor's high performance and the polymer's mechanical flexibility and robustness, while overcoming their drawbacks of those two materials. Special fabrication processes, so called “dry-transfer technique” have been used to fabricate the tactile sensor along with standard micro-fabrication processes.

A Novel Device for Total Acoustic Output Measurement of High Power Transducers

NASA Astrophysics Data System (ADS)

Howard, S.; Twomey, R.; Morris, H.; Zanelli, C. I.

2010-03-01

The objective of this work was to develop a device for ultrasound power measurement applicable over a broad range of medical transducer types, orientations and powers, and which supports automatic measurements to simplify use and minimize errors. Considering all the recommendations from standards such as IEC 61161, an accurate electromagnetic null-balance has been designed for ultrasound power measurements. The sensing element is placed in the water to eliminate errors due to surface tension and water evaporation, and the motion and detection of force is constrained to one axis, to increase immunity to vibration from the floor, water sloshing and water surface waves. A transparent tank was designed so it could easily be submerged in a larger tank to accommodate large transducers or side-firing geometries, and can also be turned upside-down for upward-firing transducers. A vacuum lid allows degassing the water and target in situ. An external control module was designed to operate the sensing/driving loop and to communicate to a local computer for data logging. The sensing algorithm, which incorporates temperature compensation, compares the feedback force needed to cancel the motion for sources in the "on" and "off" states. These two states can be controlled by the control unit or manually by the user, under guidance by a graphical user interface (the system presents measured power live during collection). Software allows calibration to standard weights, or to independently calibrated acoustic sources. The design accommodates a variety of targets, including cone, rubber, brush targets and an oil-filled target for power measurement via buoyancy changes. Measurement examples are presented, including HIFU sources operating at powers from 1 to 100.

Development of pulse-echo ultrasonic propagation imaging system and its delivery to Korea Air Force

NASA Astrophysics Data System (ADS)

Ahmed, Hasan; Hong, Seung-Chan; Lee, Jung-Ryul; Park, Jongwoon; Ihn, Jeong-Beom

2017-04-01

This paper proposes a full-field pulse-echo ultrasonic propagation imaging (FF-PE-UPI) system for non-destructive evaluation of structural defects. The system works by detection of bulk waves that travel through the thickness of a specimen. This is achieved by joining the laser beams for the ultrasonic wave generation and sensing. This enables accurate and clear damage assessment and defect localization in the thickness with minimum signal processing since bulk waves are less susceptible to dispersion during short propagation through the thickness. The system consists of a Qswitched laser for generating the aforementioned waves, a laser Doppler vibrometer (LDV) for sensing, optical elements to combine the generating and sensing laser beams, a dual-axis automated translation stage for raster scanning of the specimen and a digitizer to record the signals. A graphical user interface (GUI) is developed to control all the individual blocks of the system. Additionally, the software also manages signal acquisition, processing, and display. The GUI is created in C++ using the QT framework. In view of the requirements posed by the Korean Air Force(KAF), the system is designed to be compact and portable to allow for in situ inspection of a selected area of a larger structure such as radome or rudder of an aircraft. The GUI is designed with a minimalistic approach to promote usability and adaptability while masking the intricacies of actual system operation. Through the use of multithreading the software is able to show the results while a specimen is still being scanned. This is achieved by real-time and concurrent acquisition, processing, and display of ultrasonic signal of the latest scan point in the scan area.

A systematic evaluation of expression of HERV-W elements; influence of genomic context, viral structure and orientation

PubMed Central

2011-01-01

Background One member of the W family of human endogenous retroviruses (HERV) appears to have been functionally adopted by the human host. Nevertheless, a highly diversified and regulated transcription from a range of HERV-W elements has been observed in human tissues and cells. Aberrant expression of members of this family has also been associated with human disease such as multiple sclerosis (MS) and schizophrenia. It is not known whether this broad expression of HERV-W elements represents transcriptional leakage or specific transcription initiated from the retroviral promoter in the long terminal repeat (LTR) region. Therefore, potential influences of genomic context, structure and orientation on the expression levels of individual HERV-W elements in normal human tissues were systematically investigated. Results Whereas intronic HERV-W elements with a pseudogene structure exhibited a strong anti-sense orientation bias, intronic elements with a proviral structure and solo LTRs did not. Although a highly variable expression across tissues and elements was observed, systematic effects of context, structure and orientation were also observed. Elements located in intronic regions appeared to be expressed at higher levels than elements located in intergenic regions. Intronic elements with proviral structures were expressed at higher levels than those elements bearing hallmarks of processed pseudogenes or solo LTRs. Relative to their corresponding genes, intronic elements integrated on the sense strand appeared to be transcribed at higher levels than those integrated on the anti-sense strand. Moreover, the expression of proviral elements appeared to be independent from that of their corresponding genes. Conclusions Intronic HERV-W provirus integrations on the sense strand appear to have elicited a weaker negative selection than pseudogene integrations of transcripts from such elements. Our current findings suggest that the previously observed diversified and tissue-specific expression of elements in the HERV-W family is the result of both directed transcription (involving both the LTR and internal sequence) and leaky transcription of HERV-W elements in normal human tissues. PMID:21226900

Design of a 7-DOF slave robot integrated with a magneto-rheological haptic master

NASA Astrophysics Data System (ADS)

Hwang, Yong-Hoon; Cha, Seung-Woo; Kang, Seok-Rae; Choi, Seung-Bok

2017-04-01

In this study, a 7-DOF slave robot integrated with the haptic master is designed and its dynamic motion is controlled. The haptic master is made using a controllable magneto-rheological (MR) clutch and brake and it provides the surgeon with a sense of touch by using both kinetic and kinesthetic information. Due to the size constraint of the slave robot, a wire actuating is adopted to make the desired motion of the end-effector which has 3-DOF instead of a conventional direct-driven motor. Another motions of the link parts that have 4-DOF use direct-driven motor. In total system, for working as a haptic device, the haptic master need to receive the information of repulsive forces applied on the slave robot. Therefore, repulsive forces on the end-effector are sensed by using three uniaxial torque transducer inserted in the wire actuating system and another repulsive forces applied on link part are sensed by using 6-axis transducer that is able to sense forces and torques. Using another 6-axis transducer, verify the reliability of force information on final end of slave robot. Lastly, integrated with a MR haptic master, psycho-physical test is conducted by different operators who can feel the different repulsive force or torque generated from the haptic master which is equivalent to the force or torque occurred on the end-effector to demonstrate the effectiveness of the proposed system.

A Two-Dimensional Flow Sensor with Integrated Micro Thermal Sensing Elements and a Back Propagation Neural Network

PubMed Central

Que, Ruiyi; Zhu, Rong

2014-01-01

This paper demonstrates a novel flow sensor with two-dimensional 360° direction sensitivity achieved with a simple structure and a novel data fusion algorithm. Four sensing elements with roundabout wires distributed in four quadrants of a circle compose the sensor probe, and work in constant temperature difference (CTD) mode as both Joule heaters and temperature detectors. The magnitude and direction of a fluid flow are measured by detecting flow-induced temperature differences among the four elements. The probe is made of Ti/Au thin-film with a diameter of 2 mm, and is fabricated using micromachining techniques. When a flow goes through the sensor, the flow-induced temperature differences are detected by the sensing elements that also serve as the heaters of the sensor. By measuring the temperature differences among the four sensing elements symmetrically distributed in the sensing area, a full 360° direction sensitivity can be obtained. By using a BP neural network to model the relationship between the readouts of the four sensor elements and flow parameters and execute data fusion, the magnitude and direction of the flow can be deduced. Validity of the sensor design was proven through both simulations and experiments. Wind tunnel experimental results show that the measurement accuracy of the airflow speed reaches 0.72 m/s in the range of 3 m/s–30 m/s and the measurement accuracy of flow direction angle reaches 1.9° in the range of 360°. PMID:24385032

A two-dimensional flow sensor with integrated micro thermal sensing elements and a back propagation neural network.

PubMed

Que, Ruiyi; Zhu, Rong

2013-12-31

This paper demonstrates a novel flow sensor with two-dimensional 360° direction sensitivity achieved with a simple structure and a novel data fusion algorithm. Four sensing elements with roundabout wires distributed in four quadrants of a circle compose the sensor probe, and work in constant temperature difference (CTD) mode as both Joule heaters and temperature detectors. The magnitude and direction of a fluid flow are measured by detecting flow-induced temperature differences among the four elements. The probe is made of Ti/Au thin-film with a diameter of 2 mm, and is fabricated using micromachining techniques. When a flow goes through the sensor, the flow-induced temperature differences are detected by the sensing elements that also serve as the heaters of the sensor. By measuring the temperature differences among the four sensing elements symmetrically distributed in the sensing area, a full 360° direction sensitivity can be obtained. By using a BP neural network to model the relationship between the readouts of the four sensor elements and flow parameters and execute data fusion, the magnitude and direction of the flow can be deduced. Validity of the sensor design was proven through both simulations and experiments. Wind tunnel experimental results show that the measurement accuracy of the airflow speed reaches 0.72 m/s in the range of 3 m/s-30 m/s and the measurement accuracy of flow direction angle reaches 1.9° in the range of 360°.

Analysis of Stress Distributions Under Lightweight Wheeled Vehicles

DTIC Science & Technology

2013-10-09

For a balanced analysis it is important at examine the full scale error ε f . Sinkage error, although large in a relative sense is typically on the...director of the Edgerton Center at MIT, to Thuan Doan, and to Meccanotecnica Riesi SRL for collaborating on manufacturing the custom sensing array...a pulling/braking force at the vehicle axle. Fx = T −Rc (33) The importance of drawbar force is obvious, since a positive drawbar force implies that

Continuum Reconfigurable Parallel Robots for Surgery: Shape Sensing and State Estimation with Uncertainty.

PubMed

Anderson, Patrick L; Mahoney, Arthur W; Webster, Robert J

2017-07-01

This paper examines shape sensing for a new class of surgical robot that consists of parallel flexible structures that can be reconfigured inside the human body. Known as CRISP robots, these devices provide access to the human body through needle-sized entry points, yet can be configured into truss-like structures capable of dexterous movement and large force application. They can also be reconfigured as needed during a surgical procedure. Since CRISP robots are elastic, they will deform when subjected to external forces or other perturbations. In this paper, we explore how to combine sensor information with mechanics-based models for CRISP robots to estimate their shapes under applied loads. The end result is a shape sensing framework for CRISP robots that will enable future research on control under applied loads, autonomous motion, force sensing, and other robot behaviors.

Simulating the Activation of Voltage Sensing Domain for a Voltage-Gated Sodium Channel Using Polarizable Force Field.

PubMed

Sun, Rui-Ning; Gong, Haipeng

2017-03-02

Voltage-gated sodium (Na V ) channels play vital roles in the signal transduction of excitable cells. Upon activation of a Na V channel, the change of transmembrane voltage triggers conformational change of the voltage sensing domain, which then elicits opening of the pore domain and thus allows an influx of Na + ions. Description of this process with atomistic details is in urgent demand. In this work, we simulated the partial activation process of the voltage sensing domain of a prokaryotic Na V channel using a polarizable force field. We not only observed the conformational change of the voltage sensing domain from resting to preactive state, but also rigorously estimated the free energy profile along the identified reaction pathway. Comparison with the control simulation using an additive force field indicates that voltage-gating thermodynamics of Na V channels may be inaccurately described without considering the electrostatic polarization effect.

System and method for determination of the reflection wavelength of multiple low-reflectivity bragg gratings in a sensing optical fiber

NASA Technical Reports Server (NTRS)

Moore, Jason P. (Inventor)

2009-01-01

A system and method for determining a reflection wavelength of multiple Bragg gratings in a sensing optical fiber comprise: (1) a source laser; (2) an optical detector configured to detect a reflected signal from the sensing optical fiber; (3) a plurality of frequency generators configured to generate a signal having a frequency corresponding to an interferometer frequency of a different one of the plurality of Bragg gratings; (4) a plurality of demodulation elements, each demodulation element configured to combine the signal produced by a different one of the plurality of frequency generators with the detected signal from the sensing optical fiber; (5) a plurality of peak detectors, each peak detector configured to detect a peak of the combined signal from a different one of the demodulation elements; and (6) a laser wavenumber detection element configured to determine a wavenumber of the laser when any of the peak detectors detects a peak.

Dynamics modeling for parallel haptic interfaces with force sensing and control.

PubMed

Bernstein, Nicholas; Lawrence, Dale; Pao, Lucy

2013-01-01

Closed-loop force control can be used on haptic interfaces (HIs) to mitigate the effects of mechanism dynamics. A single multidimensional force-torque sensor is often employed to measure the interaction force between the haptic device and the user's hand. The parallel haptic interface at the University of Colorado (CU) instead employs smaller 1D force sensors oriented along each of the five actuating rods to build up a 5D force vector. This paper shows that a particular manipulandum/hand partition in the system dynamics is induced by the placement and type of force sensing, and discusses the implications on force and impedance control for parallel haptic interfaces. The details of a "squaring down" process are also discussed, showing how to obtain reduced degree-of-freedom models from the general six degree-of-freedom dynamics formulation.

Alien liquid detector and control

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

Potter, B.M.

An alien liquid detector employs a monitoring element and an energizing circuit for maintaining the temperature of the monitoring element substantially above ambient temperature. For this purpose an electronic circit controls a flow of heating current to the monitoring element. The presence of an alien liquid is detected by sensing a predetermined change in heating current flow to the monitoring element, e.g., to distinguish between water and oil. In preferred embodiments the monitoring element is a thermistor whose resistance is compared with a reference resistance and heating current through the thermistor is controlled in accordance with the difference. In onemore » embodiment a bridge circuit senses the resistance difference; the difference may be sensed by an operational amplifier arrangement. Features of the invention include positioning the monitoring element at the surface of water, slightly immersed, so that the power required to maintain the thermistor temperature substantially above ambient temperature serves to detect presence of oil pollution at the surface.« less

A self-calibrating multicomponent force/torque measuring system

NASA Astrophysics Data System (ADS)

Marangoni, Rafael R.; Schleichert, Jan; Rahneberg, Ilko; Hilbrunner, Falko; Fröhlich, Thomas

2018-07-01

A multicomponent self-calibrating force and torque sensor is presented. In this system, the principle of a Kibble balance is adapted for the traceable force and torque measurement in three orthogonal directions. The system has two operating modes: the velocity mode and the force/torque sensing mode. In the velocity mode, the calibration of the sensor is performed, while in the force/torque sensing mode, forces and torques are measured by using the principle of the electromagnetic force compensation. Details about the system are provided, with the main components of the sensor and a description of the operational procedure. A prototype of the system is currently being implemented for measuring forces and torques in a range of  ±2 N and  ±0.1 N · m respectively. A maximal relative expanded measurement uncertainty (k  =  2) of 1 · 10‑4 is expected for the force and torque measurements.

Gradiometer Using Middle Loops as Sensing Elements in a Low-Field SQUID MRI System

NASA Technical Reports Server (NTRS)

Penanen, Konstantin; Hahn, Inseob; Ho Eom, Byeong

2009-01-01

A new gradiometer scheme uses middle loops as sensing elements in lowfield superconducting quantum interference device (SQUID) magnetic resonance imaging (MRI). This design of a second order gradiometer increases its sensitivity and makes it more uniform, compared to the conventional side loop sensing scheme with a comparable matching SQUID. The space between the two middle loops becomes the imaging volume with the enclosing cryostat built accordingly.

Silicon force sensor and method of using the same

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

Galambos, Paul C.; Crenshaw, Thomas B.; Nishida, Erik E.

The various technologies presented herein relate to a sensor for measurement of high forces and/or high load shock rate(s), whereby the sensor utilizes silicon as the sensing element. A plate of Si can have a thinned region formed therein on which can be formed a number of traces operating as a Wheatstone bridge. The brittle Si can be incorporated into a layered structure comprising ductile and/or compliant materials. The sensor can have a washer-like configuration which can be incorporated into a nut and bolt configuration, whereby tightening of the nut and bolt can facilitate application of a compressive preload uponmore » the sensor. Upon application of an impact load on the bolt, the compressive load on the sensor can be reduced (e.g., moves towards zero-load), however the magnitude of the preload can be such that the load on the sensor does not translate to tensile stress being applied to the sensor.« less

A Tactile Sensor Using Piezoresistive Beams for Detection of the Coefficient of Static Friction

PubMed Central

Okatani, Taiyu; Takahashi, Hidetoshi; Noda, Kentaro; Takahata, Tomoyuki; Matsumoto, Kiyoshi; Shimoyama, Isao

2016-01-01

This paper reports on a tactile sensor using piezoresistive beams for detection of the coefficient of static friction merely by pressing the sensor against an object. The sensor chip is composed of three pairs of piezoresistive beams arranged in parallel and embedded in an elastomer; this sensor is able to measure the vertical and lateral strains of the elastomer. The coefficient of static friction is estimated from the ratio of the fractional resistance changes corresponding to the sensing elements of vertical and lateral strains when the sensor is in contact with an object surface. We applied a normal force on the sensor surface through objects with coefficients of static friction ranging from 0.2 to 1.1. The fractional resistance changes corresponding to vertical and lateral strains were proportional to the applied force. Furthermore, the relationship between these responses changed according to the coefficients of static friction. The experimental result indicated the proposed sensor could determine the coefficient of static friction before a global slip occurs. PMID:27213374

Gas sensor protection device and method

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

Boyd, David; Magera, Craig

A gas sensor includes a sensor housing and a sensing element located within the sensor housing. The sensing element has a distal end and defines an axis. The gas sensor also includes a sensor protection device coupled to the sensor housing and at least partially surrounding the distal end of the sensing element. The sensor protection device includes a first member coupled to the housing, the first member having a generally rectangular cross-sectional shape in a plane perpendicular to the axis. The first member includes a gas inlet and a gas outlet. The sensor protection device also includes a secondmore » member coupled to the housing.« less

Specific coil design for SENSE: a six-element cardiac array.

PubMed

Weiger, M; Pruessmann, K P; Leussler, C; Röschmann, P; Boesiger, P

2001-03-01

In sensitivity encoding (SENSE), the effects of inhomogeneous spatial sensitivity of surface coils are utilized for signal localization in addition to common Fourier encoding using magnetic field gradients. Unlike standard Fourier MRI, SENSE images exhibit an inhomogeneous noise distribution, which crucially depends on the geometrical sensitivity relations of the coils used. Thus, for optimum signal-to-noise-ratio (SNR) and noise homogeneity, specialized coil configurations are called for. In this article we study the implications of SENSE imaging for coil layout by means of simulations and imaging experiments in a phantom and in vivo. New, specific design principles are identified. For SENSE imaging, the elements of a coil array should be smaller than for common phased-array imaging. Furthermore, adjacent coil elements should not overlap. Based on the findings of initial investigations, a configuration of six coils was designed and built specifically for cardiac applications. The in vivo evaluation of this array showed a considerable SNR increase in SENSE images, as compared with a conventional array. Magn Reson Med 45:495-504, 2001. Copyright 2001 Wiley-Liss, Inc.

Development of a film sensor for static and dynamic force measurement

NASA Astrophysics Data System (ADS)

Castellini, P.; Montanini, R.; Revel, G. M.

2002-09-01

In this work an innovative double-layer film sensor for the measurement of forces is presented. The sensor is a thin film (thickness below 1 mm) based on a "sandwich" structure composed of two sensing elements glued together: one layer is a capacitive film and the other is a piezoelectric film. Both the layers are sensitive to compression loads, but they are suitable for working in different frequency ranges. In fact, while the capacitive element is capable of measuring from dc up to about 400 Hz, on the contrary the piezoelectric film works in the high frequency range. The output signals of both the sensors are acquired and then filtered and processed in order to achieve a single output signal. The piezocapacitive sensor has been developed in order to synthesize, in a small and cheap device, the capability to measure compression forces in a wide range of frequencies. The sensor is very small and has many potential applications, such as in the field of modal analysis. In particular, the very small thickness allows to insert it into a composite material to measure actual loads and excitations, as well as on the surface or between different components of a more complex system in order to obtain a smart structure. This article describes the realization of the sensor and the adopted signal processing strategies. The metrological characterization procedure is discussed and results are shown for both static and dynamic calibration of the film sensor. Finally, a simple application, that highlights the benefits of the sensor, is presented.

Neutron detector

DOEpatents

Stephan, Andrew C [Knoxville, TN; Jardret,; Vincent, D [Powell, TN

2011-04-05

A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

Force sensing using 3D displacement measurements in linear elastic bodies

NASA Astrophysics Data System (ADS)

Feng, Xinzeng; Hui, Chung-Yuen

2016-07-01

In cell traction microscopy, the mechanical forces exerted by a cell on its environment is usually determined from experimentally measured displacement by solving an inverse problem in elasticity. In this paper, an innovative numerical method is proposed which finds the "optimal" traction to the inverse problem. When sufficient regularization is applied, we demonstrate that the proposed method significantly improves the widely used approach using Green's functions. Motivated by real cell experiments, the equilibrium condition of a slowly migrating cell is imposed as a set of equality constraints on the unknown traction. Our validation benchmarks demonstrate that the numeric solution to the constrained inverse problem well recovers the actual traction when the optimal regularization parameter is used. The proposed method can thus be applied to study general force sensing problems, which utilize displacement measurements to sense inaccessible forces in linear elastic bodies with a priori constraints.

Modeling and predictions of biphasic mechanosensitive cell migration altered by cell-intrinsic properties and matrix confinement.

PubMed

Pathak, Amit

2018-04-12

Motile cells sense the stiffness of their extracellular matrix (ECM) through adhesions and respond by modulating the generated forces, which in turn lead to varying mechanosensitive migration phenotypes. Through modeling and experiments, cell migration speed is known to vary with matrix stiffness in a biphasic manner, with optimal motility at an intermediate stiffness. Here, we present a two-dimensional cell model defined by nodes and elements, integrated with subcellular modeling components corresponding to mechanotransductive adhesion formation, force generation, protrusions and node displacement. On 2D matrices, our calculations reproduce the classic biphasic dependence of migration speed on matrix stiffness and predict that cell types with higher force-generating ability do not slow down on very stiff matrices, thus disabling the biphasic response. We also predict that cell types defined by lower number of total receptors require stiffer matrices for optimal motility, which also limits the biphasic response. For a cell type with robust biphasic migration on 2D surface, simulations in channel-like confined environments of varying width and height predict faster migration in more confined matrices. Simulations performed in shallower channels predict that the biphasic mechanosensitive cell migration response is more robust on 2D micro-patterns as compared to the channel-like 3D confinement. Thus, variations in the dimensionality of matrix confinement alters the way migratory cells sense and respond to the matrix stiffness. Our calculations reveal new phenotypes of stiffness- and topography-sensitive cell migration that critically depend on both cell-intrinsic and matrix properties. These predictions may inform our understanding of various mechanosensitive modes of cell motility that could enable tumor invasion through topographically heterogeneous microenvironments. © 2018 IOP Publishing Ltd.

Spaceborne Studies Of Ocean Circulation

NASA Astrophysics Data System (ADS)

Patzert, William C.

1984-08-01

The global view of the oceans seen by Seasat during its 1978 flight demonstrated the feasibility of ocean remote sensing. These first-ever global data sets of sea surface topography (altimeter) and marine winds (scatterometer) laid the foundation for two satellite missions planned for the late 1980's. The future missions are the next generation of altimeter and scatterometer to be flown aboard TOPEX (Topography Experiment) and NROSS (Navy Remote Ocean Sensing System), respectively. The data from these satellites will be coordinated with measurements made at sea to determine the driving forces of ocean circulation and to study the oceans role in climate variability. Sea surface winds (calculated from scatterometer measurements) are the fundamental driving force for ocean waves and currents (estimated from altimeter measurements). On a global scale, the winds and currents are approximately equal partners in redistributing the excess heat gained in the tropics from solar radiation to the cooler polar regions. Small perturbations in this system can dramatically alter global weather, such as the El Niho event of 1982-83. During an El Ni?io event, global wind patterns and ocean currents are perturbed causing unusual ocean warming in the tropical Pacfic Ocean. These ocean events are coupled to complex fluctuations in global weather. Only with satellites will we be able to collect the global data sets needed to study events such as El Ni?o. When TOPEX and NROSS fly, oceanographers will have the equivalent of meteorological high and low pressure charts of ocean topography as well as the surface winds to study ocean "weather." This ability to measure ocean circulation and its driving forces is a critical element in understanding the influence of oceans on society. Climatic changes, fisheries, commerce, waste disposal, and national defense are all involved.

Coherent Two-Mode Dynamics of a Nanowire Force Sensor

NASA Astrophysics Data System (ADS)

Braakman, Floris R.; Rossi, Nicola; Tütüncüoglu, Gözde; Morral, Anna Fontcuberta i.; Poggio, Martino

2018-05-01

Classically coherent dynamics analogous to those of quantum two-level systems are studied in the setting of force sensing. We demonstrate quantitative control over the coupling between two orthogonal mechanical modes of a nanowire cantilever through measurement of avoided crossings as we deterministically position the nanowire inside an electric field. Furthermore, we demonstrate Rabi oscillations between the two mechanical modes in the strong-coupling regime. These results give prospects of implementing coherent two-mode control techniques for force-sensing signal enhancement.

Let physics substantiate music and music enhance physics- give principle to the other disciplines.

NASA Astrophysics Data System (ADS)

Chang, Hui-Yiing

2006-03-01

A conventional practice in K-12 education is to synchronize the arts and the sciences. Physics, traditionally been considered the mother of the sciences, and music, the mother of the arts, are interdependent and help to establishing a complete understanding of the other disciplines. Intense musical expression is attained when progression aims towards infinity. Motions are made in curves across time, imitating physical phenomena. The meaning of each element is enhanced according to the relative duration and dynamics of its context. Complete musical expression considers the three dimensions of space- length, breadth and height- and the three dimensions of time- past, present and future when balancing the instrumental parts and developing the structural elements. Overall, equilibrium is sought for like gravitational forces as expressed in equations. In learning processes, sensing precedes reasoning. Music attunes one to sensitive reactions towards the environment while physics substantiates the concepts by imposing a hierarchical order, the highest form of which is elegantly beautiful and most effectively expressed in music.

Cross-shaped torsional spring

DOEpatents

Williamson, Matthew M.; Pratt, Gill A.

1999-06-08

The invention provides an elastic actuator consisting of a motor and a motor drive transmission connected at an output of the motor. An elastic element is connected in series with the motor drive transmission, and this elastic element is positioned to alone support the full weight of any load connected at an output of the actuator. A single force transducer is positioned at a point between a mount for the motor and an output of the actuator. This force transducer generates a force signal, based on deflection of the elastic element, that indicates force applied by the elastic element to an output of the actuator. An active feedback force control loop is connected between the force transducer and the motor for controlling the motor. This motor control is based on the force signal to deflect the elastic element an amount that produces a desired actuator output force. The produced output force is substantially independent of load motion. The invention also provides a torsional spring consisting of a flexible structure having at least three flat sections each connected integrally with and extending radially from a central section. Each flat section extends axially along the central section from a distal end of the central section to a proximal end of the central section.

Nitrogen dioxide detection

DOEpatents

Sinha, Dipen N.; Agnew, Stephen F.; Christensen, William H.

1993-01-01

Method and apparatus for detecting the presence of gaseous nitrogen dioxide and determining the amount of gas which is present. Though polystyrene is normally an insulator, it becomes electrically conductive in the presence of nitrogen dioxide. Conductance or resistance of a polystyrene sensing element is related to the concentration of nitrogen dioxide at the sensing element.

Impaired force control in writer's cramp showing a bilateral deficit in sensorimotor integration.

PubMed

Bleton, Jean-Pierre; Teremetz, Maxime; Vidailhet, Marie; Mesure, Serge; Maier, Marc A; Lindberg, Påvel G

2014-01-01

Abnormal cortical processing of sensory inputs has been found bilaterally in writer's cramp (WC). This study tested the hypothesis that patients with WC have an impaired ability to adjust grip forces according to visual and somatosensory cues in both hands. A unimanual visuomotor force-tracking task and a bimanual sense of effort force-matching task were performed by WC patients and healthy controls. In visuomotor tracking, WC patients showed increased error, greater variability, and longer release duration than controls. In the force-matching task, patients underestimated, whereas controls overestimated, the force applied in the other hand. Visuomotor tracking and force matching were equally impaired in both the symptomatic and nonsymptomatic hand in WC patients. This study provides evidence of bilaterally impaired grip-force control in WC, when using visual or sense of effort cues. This suggests a generalized subclinical deficit in sensorimotor integration in WC. Copyright © 2013 Movement Disorder Society.

Multi-range force sensors utilizing shape memory alloys

DOEpatents

Varma, Venugopal K.

2003-04-15

The present invention provides a multi-range force sensor comprising a load cell made of a shape memory alloy, a strain sensing system, a temperature modulating system, and a temperature monitoring system. The ability of the force sensor to measure contact forces in multiple ranges is effected by the change in temperature of the shape memory alloy. The heating and cooling system functions to place the shape memory alloy of the load cell in either a low temperature, low strength phase for measuring small contact forces, or a high temperature, high strength phase for measuring large contact forces. Once the load cell is in the desired phase, the strain sensing system is utilized to obtain the applied contact force. The temperature monitoring system is utilized to ensure that the shape memory alloy is in one phase or the other.

Biologically inspired multi-layered synthetic skin for tactile feedback in prosthetic limbs.

PubMed

Osborn, Luke; Nguyen, Harrison; Betthauser, Joseph; Kaliki, Rahul; Thakor, Nitish

2016-08-01

The human body offers a template for many state-of-the-art prosthetic devices and sensors. In this work, we present a novel, sensorized synthetic skin that mimics the natural multi-layered nature of mechanoreceptors found in healthy glabrous skin to provide tactile information. The multi-layered sensor is made up of flexible piezoresistive textiles that act as force sensitive resistors (FSRs) to convey tactile information, which are embedded within a silicone rubber to resemble the compliant nature of human skin. The top layer of the synthetic skin is capable of detecting small loads less than 5 N whereas the bottom sensing layer responds reliably to loads over 7 N. Finite element analysis (FEA) of a simplified human fingertip and the synthetic skin was performed. Results suggest similarities in behavior during loading. A natural tactile event is simulated by loading the synthetic skin on a prosthetic limb. Results show the sensors' ability to detect applied loads as well as the ability to simulate neural spiking activity based on the derivative and temporal differences of the sensor response. During the tactile loading, the top sensing layer responded 0.24 s faster than the bottom sensing layer. A synthetic biologically-inspired skin such as this will be useful for enhancing the functionality of prosthetic limbs through tactile feedback.

Development and characterization of silicone embedded distributed piezoelectric sensors for contact detection

NASA Astrophysics Data System (ADS)

Acer, Merve; Salerno, Marco; Agbeviade, Kossi; Paik, Jamie

2015-07-01

Tactile sensing transfers complex interactive information in a most intuitive sense. Such a populated set of data from the environment and human interactions necessitates various degrees of information from both modular and distributed areas. A sensor design that could provide such types of feedback becomes challenging when the target component has a nonuniform, agile, high resolution, and soft surface. This paper presents an innovative methodology for the manufacture of novel soft sensors that have a high resolution sensing array due to the sensitivity of ceramic piezoelectric (PZT) elements, while uncommonly matched with the high stretchability of the soft substrate and electrode design. Further, they have a low profile and their transfer function is easy to tune by changing the material and thickness of the soft substrate in which the PZTs are embedded. In this manuscript, we present experimental results of the soft sensor prototypes: PZTs arranged in a four by two array form, measuring 1.5-2.3 mm in thickness, with the sensitivity in the range of 0.07-0.12 of the normalized signal change per unit force. We have conducted extensive tests under dynamic loading conditions that include impact, step and cyclic. The presented prototype's mechanical and functional capacities are promising for applications in biomedical systems where soft, wearable and high precision sensors are needed.

Elastic actuator for precise force control

DOEpatents

Pratt, G.A.; Williamson, M.M.

1997-07-22

The invention provides an elastic actuator consisting of a motor and a motor drive transmission connected at an output of the motor. An elastic element is connected in series with the motor drive transmission, and this elastic element is positioned to alone support the full weight of any load connected at an output of the actuator. A single force transducer is positioned at a point between a mount for the motor and an output of the actuator. This force transducer generates a force signal, based on deflection of the elastic element, that indicates force applied by the elastic element to an output of the actuator. An active feedback force control loop is connected between the force transducer and the motor for controlling the motor. This motor control is based on the force signal to deflect the elastic element an amount that produces a desired actuator output force. The produced output force is substantially independent of load motion. The invention also provides a torsional spring consisting of a flexible structure having at least three flat sections each connected integrally with and extending radially from a central section. Each flat section extends axially along the central section from a distal end of the central section to a proximal end of the central section. 30 figs.

Elastic actuator for precise force control

DOEpatents

Pratt, Gill A.; Williamson, Matthew M.

1997-07-22

The invention provides an elastic actuator consisting of a motor and a motor drive transmission connected at an output of the motor. An elastic element is connected in series with the motor drive transmission, and this elastic element is positioned to alone support the full weight of any load connected at an output of the actuator. A single force transducer is positioned at a point between a mount for the motor and an output of the actuator. This force transducer generates a force signal, based on deflection of the elastic element, that indicates force applied by the elastic element to an output of the actuator. An active feedback force control loop is connected between the force transducer and the motor for controlling the motor. This motor control is based on the force signal to deflect the elastic element an amount that produces a desired actuator output force. The produced output force is substantially independent of load motion. The invention also provides a torsional spring consisting of a flexible structure having at least three flat sections each connected integrally with and extending radially from a central section. Each flat section extends axially along the central section from a distal end of the central section to a proximal end of the central section.

A Study in HRT Resolution: Seeking Maximum Sensitivity Among Variations in Sensing Element Material

NASA Technical Reports Server (NTRS)

Morales, Jeremy M.

2005-01-01

The EXACT (Experiments Along Coexistence near Tricriticality) project endeavors to perform the most rigorous test to date of Renormalization Group theory. In most cases, the theory gives only approximate solutions, but it offers exact predictions in the case of the He-3-He-4 tricritical point. Currently, the project is focused on maximizing the performance of the low-temperature system's HRT (high resolution thermometer) near the tricritical point. The HRT uses a PdMn sensing element, the qualities of which change based on its Mn concentration and whether or not it is annealed. All sensing element combinations will be catalogued, and through the data, the optimum configuration will be reported.

Number and density discrimination rely on a common metric: Similar psychophysical effects of size, contrast, and divided attention.

PubMed

Tibber, Marc S; Greenwood, John A; Dakin, Steven C

2012-06-04

While observers are adept at judging the density of elements (e.g., in a random-dot image), it has recently been proposed that they also have an independent visual sense of number. To test the independence of number and density discrimination, we examined the effects of manipulating stimulus structure (patch size, element size, contrast, and contrast-polarity) and available attentional resources on both judgments. Five observers made a series of two-alternative, forced-choice discriminations based on the relative numerosity/density of two simultaneously presented patches containing 16-1,024 Gaussian blobs. Mismatches of patch size and element size (across reference and test) led to bias and reduced sensitivity in both tasks, whereas manipulations of contrast and contrast-polarity had varied effects on observers, implying differing strategies. Nonetheless, the effects reported were consistent across density and number judgments, the only exception being when luminance cues were made available. Finally, density and number judgment were similarly impaired by attentional load in a dual-task experiment. These results are consistent with a common underlying metric to density and number judgments, with the caveat that additional cues may be exploited when they are available.

Structural and Machine Design Using Piezoceramic Materials: A Guide for Structural Design Engineers

NASA Technical Reports Server (NTRS)

Inman, Daniel J.; Cudney, Harley H.

2000-01-01

Using piezoceramic materials is one way the design engineer can create structures which have an ability to both sense and respond to their environment. Piezoceramic materials can be used to create structural sensors and structural actuators. Because piezoceramic materials have transduction as a material property, their sensing or actuation functions are a result of what happens to the material. This is different than discrete devices we might attach to the structure. For example, attaching an accelerometer to a structure will yield an electrical signal proportional to the acceleration at the attachment point on the structure. Using a electromagnetic shaker as an actuator will create an applied force at the attachment point. Active material elements in a structural design are not easily modeled as providing transduction at a point, but rather they change the physics of the structure in the areas where they are used. Hence, a designer must not think of adding discrete devices to a structure to obtain an effect, but rather must design a structural system which accounts for the physical principles of all the elements in the structure. The purpose of this manual is to provide practicing engineers the information necessary to incorporate piezoelectric materials in structural design and machine design. First, we will review the solid-state physics of piezoelectric materials. Then we will discuss the physical characteristics of the electrical-active material-structural system. We will present the elements of this system which must be considered as part of the design task for a structural engineer. We will cover simple modeling techniques and review the features and capabilities of commercial design tools that are available. We will then cover practical how-to elements of working with piezoceramic materials. We will review sources of piezoceramic materials and built-up devices, and their characteristics. Finally, we will provide two design examples using piezoceramic materials, first as discrete actuators for vibration isolation, and second as structurally-distributed sensor/actuators for active acoustic control.

DIFFERENTIAL FAULT SENSING CIRCUIT

DOEpatents

Roberts, J.H.

1961-09-01

A differential fault sensing circuit is designed for detecting arcing in high-voltage vacuum tubes arranged in parallel. A circuit is provided which senses differences in voltages appearing between corresponding elements likely to fault. Sensitivity of the circuit is adjusted to some level above which arcing will cause detectable differences in voltage. For particular corresponding elements, a group of pulse transformers are connected in parallel with diodes connected across the secondaries thereof so that only voltage excursions are transmitted to a thyratron which is biased to the sensitivity level mentioned.

Probing the surface profile and friction behavior of heterogeneous polymers: a molecular dynamics study

NASA Astrophysics Data System (ADS)

Dai, L.; Sorkin, V.; Zhang, Y. W.

2017-04-01

We perform molecular dynamics simulations to investigate molecular structure alternation and friction behavior of heterogeneous polymer (perfluoropolyether) surfaces using a nanoscale probing tip (tetrahedral amorphous carbon). It is found that depending on the magnitude of the applied normal force, three regimes exist: the shallow depth-sensing (SDS), deep depth-sensing (DDS), and transitional depth-sensing (TDS) regimes; TDS is between SDS and DDS. In SDS, the tip is floating on the polymer surface and there is insignificant permanent alternation in the polymer structure due to largely recoverable atomic deformations, and the surface roughness profile can be accurately measured. In DDS, the tip is plowing through the polymer surface and there is significant permanent alternation in the molecular structure. In this regime, the lateral friction force rises sharply and fluctuates violently when overcoming surface pile-ups. In SDS, the friction can be described by a modified Amonton’s law including the adhesion effect; meanwhile, in DDS, the adhesion effect is negligible but the friction coefficient is significantly higher. The underlying reason for the difference in these regimes rests upon different contributions by the repulsion and attraction forces between the tip and polymer surfaces to the friction force. Our findings here reveal important insights into lateral depth-sensing on heterogeneous polymer surfaces and may help improve the precision of depth-sensing devices.

Bilateral Proprioceptive Evaluation in Individuals With Unilateral Chronic Ankle Instability

PubMed Central

Sousa, Andreia S. P.; Leite, João; Costa, Bianca; Santos, Rubim

2017-01-01

Context: Despite extensive research on chronic ankle instability, the findings regarding proprioception have been conflicting and focused only on the injured limb. Also, the different components of proprioception have been evaluated in isolation. Objective: To evaluate bilateral ankle proprioception in individuals with unilateral ankle instability. Design: Cohort study. Setting: Research laboratory center in a university. Patients or Other Participants: Twenty-four individuals with a history of unilateral ankle sprain and chronic ankle instability (mechanical ankle instability group, n = 10; functional ankle instability [FAI] group, n = 14) and 20 controls. Main Outcome Measure(s): Ankle active and passive joint position sense, kinesthesia, and force sense. Results: We observed a significant interaction between the effects of limb and group for kinesthesia (F = 3.27, P = .049). Increased error values were observed in the injured limb of the FAI group compared with the control group (P = .031, Cohen d = 0.47). Differences were also evident for force sense (F = 9.31, P < .001): the FAI group demonstrated increased error versus the control group (injured limb: P < .001, Cohen d = 1.28; uninjured limb: P = .009, Cohen d = 0.89) and the mechanical ankle instability group (uninjured limb: P = .023, Cohen d = 0.76). Conclusions: Individuals with unilateral FAI had increased error ipsilaterally (injured limb) for inversion movement detection (kinesthesia) and evertor force sense and increased error contralaterally (uninjured limb) for evertor force sense. PMID:28318316

Remote sensing and image interpretation

NASA Technical Reports Server (NTRS)

Lillesand, T. M.; Kiefer, R. W. (Principal Investigator)

1979-01-01

A textbook prepared primarily for use in introductory courses in remote sensing is presented. Topics covered include concepts and foundations of remote sensing; elements of photographic systems; introduction to airphoto interpretation; airphoto interpretation for terrain evaluation; photogrammetry; radiometric characteristics of aerial photographs; aerial thermography; multispectral scanning and spectral pattern recognition; microwave sensing; and remote sensing from space.

Investigation of the applicability of using the triple redundant hydrogen sensor for methane sensing

NASA Technical Reports Server (NTRS)

Lantz, J. B.; Wynveen, R. A.

1983-01-01

Application specifications for the methane sensor were assembled and design guidelines, development goals and evaluation criteria were formulated. This was done to provide a framework to evaluate sensor performance and any design adjustments to the preprototype sensor that could be required to provide methane sensitivity. Good response to hydrogen was experimentally established for four hydrogen sensor elements to be later evaluated for methane response. Prior results were assembled and analyzed for other prototype hydrogen sensor performance parameters to form a comparison base. The four sensor elements previously shown to have good hydrogen response were experimentally evaluated for methane response in 2.5% methane-in-air. No response was obtained for any of the elements, despite the high methane concentration used (50% of the Lower Flammability Limit). It was concluded that the preprototype sensing elements were insensitive to methane and were hydrogen specific. Alternative sensor operating conditions and hardware design changes were considered to provide methane sensitivity to the preprototype sensor, including a variety of different methane sensing techniques. Minor changes to the existing sensor elements, sensor geometry and operating conditions will not make the preprototype hydrogen sensor respond to methane. New sensor elements that will provide methane and hydrogen sensitivity require replacement of the existing thermistor type elements. Some hydrogen sensing characteristics of the modified sensor will be compromised (larger in situ calibration gas volume and H2 nonspecificity). The preprototype hydrogen sensor should be retained for hydrogen monitoring and a separate methane sensor should be developed.

Fabrication of a self-sensing electroactive polymer bimorph actuator based on polyvinylidene fluoride and its electrostrictive terpolymer

NASA Astrophysics Data System (ADS)

Engel, Leeya; Van Volkinburg, Kyle R.; Ben-David, Moti; Washington, Gregory N.; Krylov, Slava; Shacham-Diamand, Yosi

2016-04-01

In this paper, we report on the fabrication of a self-sensing electroactive polymer cantilevered bimorph beam actuator and its frequency response. Tip deflections of the beam, induced by applying an AC signal across ferroelectric relaxor polyvinylidene fluoride-trifluoroethylene chlorotrifluoroethylene (P(VDF-TrFE-CTFE)), reached a magnitude of 350μm under a field of ~55MV/m and were recorded externally using a laser Doppler vibrometer (LDV). Deflections were determined simultaneously by applying a sensing model to the voltage measured across the bimorph's integrated layer of piezoelectric polymer polyvinylidene fluoride (PVDF). The sensing model treats the structure as a simple Euler- Bernoulli cantilevered beam with two distributed active elements represented through the use of generalized functions and offers a method through which real time tip deflection can be measured without the need for external visualization. When not being used as a sensing element, the PVDF layer can provide an additional means for actuation of the beam via the converse piezoelectric effect, resulting in bidirectional control of the beam's deflections. Integration of flexible sensing elements together with modeling of the electroactive polymer beam can benefit the developing field of polymer microactuators which have applications in soft robotics as "smart" prosthetics/implants, haptic displays, tools for less invasive surgery, and sensing.

Accuracy improvement in the TDR-based localization of water leaks

NASA Astrophysics Data System (ADS)

Cataldo, Andrea; De Benedetto, Egidio; Cannazza, Giuseppe; Monti, Giuseppina; Demitri, Christian

A time domain reflectometry (TDR)-based system for the localization of water leaks has been recently developed by the authors. This system, which employs wire-like sensing elements to be installed along the underground pipes, has proven immune to the limitations that affect the traditional, acoustic leak-detection systems. Starting from the positive results obtained thus far, in this work, an improvement of this TDR-based system is proposed. More specifically, the possibility of employing a low-cost, water-absorbing sponge to be placed around the sensing element for enhancing the accuracy in the localization of the leak is addressed. To this purpose, laboratory experiments were carried out mimicking a water leakage condition, and two sensing elements (one embedded in a sponge and one without sponge) were comparatively used to identify the position of the leak through TDR measurements. Results showed that, thanks to the water retention capability of the sponge (which maintains the leaked water more localized), the sensing element embedded in the sponge leads to a higher accuracy in the evaluation of the position of the leak.

Hybrid SnO2/TiO2 Nanocomposites for Selective Detection of Ultra-Low Hydrogen Sulfide Concentrations in Complex Backgrounds

PubMed Central

Larin, Alexander; Womble, Phillip C.; Dobrokhotov, Vladimir

2016-01-01

In this paper, we present a chemiresistive metal oxide (MOX) sensor for detection of hydrogen sulfide. Compared to the previous reports, the overall sensor performance was improved in multiple characteristics, including: sensitivity, selectivity, stability, activation time, response time, recovery time, and activation temperature. The superior sensor performance was attributed to the utilization of hybrid SnO2/TiO2 oxides as interactive catalytic layers deposited using a magnetron radio frequency (RF) sputtering technique. The unique advantage of the RF sputtering for sensor fabrication is the ability to create ultra-thin films with precise control of geometry, morphology and chemical composition of the product of synthesis. Chemiresistive films down to several nanometers can be fabricated as sensing elements. The RF sputtering technique was found to be very robust for bilayer and multilayer oxide structure fabrication. The geometry, morphology, chemical composition and electronic structure of interactive layers were evaluated in relation to their gas sensing performance, using scanning electron microscopy (SEM), X-ray diffraction technique (XRD), atomic force microscopy (AFM), Energy Dispersive X-ray Spectroscopy (EDAX), UV visible spectroscopy, and Kelvin probe measurements. A sensor based on multilayer SnO2/TiO2 catalytic layer with 10% vol. content of TiO2 demonstrated the best gas sensing performance in all characteristics. Based on the pattern relating material’s characteristics to gas sensing performance, the optimization strategy for hydrogen sulfide sensor fabrication was suggested. PMID:27618900

EXOS research on force-reflecting controllers

NASA Astrophysics Data System (ADS)

Eberman, Brian S.; An, Bin

1993-03-01

EXOS has developed two state of the art prototype master controllers for controlling robot hands and manipulators under the Small Business Innovation Research (SBIR) program with NASA. One such device is a two degree-of-freedom Sensing and Force Reflecting Exoskeleton (SAFiRE) worn on the operator's hand. The device measures the movement of the index finger and reflects the interaction forces between the slave robot and the environment to the human finger. The second device is a position sensing Exoskeleton ArmMaster (EAM) worn by a human operator. The device simultaneously tracks the motions of the operator's three DOF shoulder and two DOF elbow. Both of these devices are currently used to control robots at NASA. We are currently developing a full fingered SAFiRE and a position sensing and force reflecting EAM under two second phase SBIR grants with NASA. This paper will include discussions of: (1) the design of the current prototypes, (2) kinematics of the EAM and force control of the SAFiRE, (3) design issues that must be addressed in developing more advanced versions, and (4) our progress to date in addressing these issues.

Program Calculates Forces in Bolted Structural Joints

NASA Technical Reports Server (NTRS)

Buder, Daniel A.

2005-01-01

FORTRAN 77 computer program calculates forces in bolts in the joints of structures. This program is used in conjunction with the NASTRAN finite-element structural-analysis program. A mathematical model of a structure is first created by approximating its load-bearing members with representative finite elements, then NASTRAN calculates the forces and moments that each finite element contributes to grid points located throughout the structure. The user selects the finite elements that correspond to structural members that contribute loads to the joints of interest, and identifies the grid point nearest to each such joint. This program reads the pertinent NASTRAN output, combines the forces and moments from the contributing elements to determine the resultant force and moment acting at each proximate grid point, then transforms the forces and moments from these grid points to the centroids of the affected joints. Then the program uses these joint loads to obtain the axial and shear forces in the individual bolts. The program identifies which bolts bear the greatest axial and/or shear loads. The program also performs a fail-safe analysis in which the foregoing calculations are repeated for a sequence of cases in which each fastener, in turn, is assumed not to transmit an axial force.

Improved accuracy for finite element structural analysis via an integrated force method

NASA Technical Reports Server (NTRS)

Patnaik, S. N.; Hopkins, D. A.; Aiello, R. A.; Berke, L.

1992-01-01

A comparative study was carried out to determine the accuracy of finite element analyses based on the stiffness method, a mixed method, and the new integrated force and dual integrated force methods. The numerical results were obtained with the following software: MSC/NASTRAN and ASKA for the stiffness method; an MHOST implementation method for the mixed method; and GIFT for the integrated force methods. The results indicate that on an overall basis, the stiffness and mixed methods present some limitations. The stiffness method generally requires a large number of elements in the model to achieve acceptable accuracy. The MHOST method tends to achieve a higher degree of accuracy for course models than does the stiffness method implemented by MSC/NASTRAN and ASKA. The two integrated force methods, which bestow simultaneous emphasis on stress equilibrium and strain compatibility, yield accurate solutions with fewer elements in a model. The full potential of these new integrated force methods remains largely unexploited, and they hold the promise of spawning new finite element structural analysis tools.

Liquid level sensing device

DOEpatents

Tokarz, Richard D.

1983-01-01

A liquid level sensing device comprising a load cell supporting a column or stack of segments freely resting on one another. The density of each element is substantially identical to that of the surrounding liquid. The elements are freely guided within a surrounding tube. As each element is exposed above the liquid level, its weight will be impressed through the column to the load cell, thereby providing a signal at the load cell directly proportional to the liquid level elevation.

Combined passive magnetic bearing element and vibration damper

DOEpatents

Post, Richard F.

2001-01-01

A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium and dampen transversely directed vibrations. Mechanical stabilizers are provided to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. In a improvement over U.S. Pat. No. 5,495,221, a magnetic bearing element is combined with a vibration damping element to provide a single upper stationary dual-function element. The magnetic forces exerted by such an element, enhances levitation of the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations, and suppresses the effects of unbalance or inhibits the onset of whirl-type rotor-dynamic instabilities. Concurrently, this equilibrium is made stable against displacement-dependent drag forces of the rotating object from its equilibrium position.

Precision force sensing with optically-levitated nanospheres

NASA Astrophysics Data System (ADS)

Geraci, Andrew

2017-04-01

In high vacuum, optically-trapped dielectric nanospheres achieve excellent decoupling from their environment and experience minimal friction, making them ideal for precision force sensing. We have shown that 300 nm silica spheres can be used for calibrated zeptonewton force measurements in a standing-wave optical trap. In this optical potential, the known spacing of the standing wave anti-nodes can serve as an independent calibration tool for the displacement spectrum of the trapped particle. I will describe our progress towards using these sensors for tests of the Newtonian gravitational inverse square law at micron length scales. Optically levitated dielectric objects also show promise for a variety of other precision sensing applications, including searches for gravitational waves and other experiments in quantum optomechanics. National Science Foundation PHY-1205994, PHY-1506431, PHY-1509176.

Cross-shaped torsional spring

DOEpatents

Williamson, M.M.; Pratt, G.A.

1999-06-08

The invention provides an elastic actuator consisting of a motor and a motor drive transmission connected at an output of the motor. An elastic element is connected in series with the motor drive transmission, and this elastic element is positioned to alone support the full weight of any load connected at an output of the actuator. A single force transducer is positioned at a point between a mount for the motor and an output of the actuator. This force transducer generates a force signal, based on deflection of the elastic element, that indicates force applied by the elastic element to an output of the actuator. An active feedback force control loop is connected between the force transducer and the motor for controlling the motor. This motor control is based on the force signal to deflect the elastic element an amount that produces a desired actuator output force. The produced output force is substantially independent of load motion. The invention also provides a torsional spring consisting of a flexible structure having at least three flat sections each connected integrally with and extending radially from a central section. Each flat section extends axially along the central section from a distal end of the central section to a proximal end of the central section. 30 figs.

A temperature-compensated optical fiber force sensor for minimally invasive surgeries

NASA Astrophysics Data System (ADS)

Mo, Z.; Xu, W.; Broderick, N.; Chen, H.

2015-12-01

Force sensing in minimally invasive surgery (MIS) is a chronic problem since it has an intensive magnetic resonance (MR) operation environment, which causes a high influence to traditional electronic force sensors. Optical sensor is a promising choice in this area because it is immune to MR influence. However, the changing temperature introduces a lot of noise signals to them, which is the main obstacle for optical sensing applications in MIS. This paper proposes a miniature temperature-compensated optical force sensor by using Fabry-Perot interference (FPI) principle. It can be integrated into medical tools' tips and the temperature noise is decreased by using a reference FPI temperature sensor. An injection needle with embedded temperature-compensated FPI force sensor has been fabricated and tested. And the comparison between temperature-force simulation results and the temperature-force experiment results has been carried out.

Recording forces exerted on the bowel wall during colonoscopy: in vitro evaluation.

PubMed

Dogramadzi, S; Virk, G S; Bell, G D; Rowland, R S; Hancock, J

2005-12-01

A novel system for distributed force measurement between the bowel wall and the shaft of a colonoscope is presented. The system, based on the piezoresistive method, involves the integration of soft miniature transducers to a colonoscope to enable a wide range of forces to be sensed. The attached sensing sheath does not restrict the propulsion of the colonoscope nor notably alter its flexibility. The addition of the sensor sheath increases the colonoscope diameter by 15-20% depending on the type of the colonoscope (adult or paediatric). The transducer's accuracy is +/-20 grammes if it is not subjected to extensive static forces. Under large static force conditions the errors may increase to +/-50 grammes. The tactile force measuring sensors have provided preliminary results from experiments on a model of the large bowel. The force measurements confirm the predictions on the location and magnitude of the forces and that most of the forces are exerted whilst the instrument is looping. Copyright 2005 John Wiley & Sons, Ltd.

A droplet-based passive force sensor for remote tactile sensing applications

NASA Astrophysics Data System (ADS)

Nie, Baoqing; Yao, Ting; Zhang, Yiqiu; Liu, Jian; Chen, Xinjian

2018-01-01

A droplet-based flexible wireless force sensor has been developed for remote tactile-sensing applications. By integration of a droplet-based capacitive sensing unit and two circular planar coils, this inductor-capacitor (LC) passive sensor offers a platform for the mechanical force detection in a wireless transmitting mode. Under external loads, the membrane surface of the sensor deforms the underlying elastic droplet uniformly, introducing a capacitance response in tens of picofarads. The LC circuit transduces the applied force into corresponding variations of its resonance frequency, which is detected by an external electromagnetic coupling coil. Specifically, the liquid droplet features a mechanosensitive plasticity, which results in an increased device sensitivity as high as 2.72 MHz N-1. The high dielectric property of the droplet endows our sensor with high tolerance for noise and large capacitance values (20-40 pF), the highest value in the literature for the LC passive devices in comparable dimensions. It achieves excellent reproducibility under periodical loads ranging from 0 to 1.56 N and temperature fluctuations ranging from 10 °C to 55 °C. As an interesting conceptual demonstration, the flexible device has been configured into a fingertip-amounted setting in a highly compact package (of 11 mm × 11 mm × 0.25 mm) for remote contact force sensing in the table tennis game.

Human Eye Phantom for Developing Computer and Robot-Assisted Epiretinal Membrane Peeling*

PubMed Central

Gupta, Amrita; Gonenc, Berk; Balicki, Marcin; Olds, Kevin; Handa, James; Gehlbach, Peter; Taylor, Russell H.; Iordachita, Iulian

2014-01-01

A number of technologies are being developed to facilitate key intraoperative actions in vitreoretinal microsurgery. There is a need for cost-effective, reusable benchtop eye phantoms to enable frequent evaluation of these developments. In this study, we describe an artificial eye phantom for developing intraocular imaging and force-sensing tools. We test four candidate materials for simulating epiretinal membranes using a handheld tremor-canceling micromanipulator with force-sensing micro-forceps tip and demonstrate peeling forces comparable to those encountered in clinical practice. PMID:25571573

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

Raja, Shilpa N.; Zherebetskyy, Danylo; Wu, Siva

Nanoscale stress-sensing can be used across fields ranging from detection of incipient cracks in structural mechanics to monitoring forces in biological tissues. We demonstrate how tetrapod quantum dots (tQDs) embedded in block copolymers act as sensors of tensile/compressive stress. Remarkably, tQDs can detect their own composite dispersion and mechanical properties with a switch in optomechanical response when tQDs are in direct contact. Using experimental characterizations, atomistic simulations and finite-element analyses, we show that under tensile stress, densely packed tQDs exhibit a photoluminescence peak shifted to higher energies ("blue-shift") due to volumetric compressive stress in their core; loosely packed tQDs exhibitmore » a peak shifted to lower energies ("red-shift") from tensile stress in the core. The stress shifts result from the tQD's unique branched morphology in which the CdS arms act as antennas that amplify the stress in the CdSe core. Our nanocomposites exhibit excellent cyclability and scalability with no degraded properties of the host polymer. Colloidal tQDs allow sensing in many materials to potentially enable autoresponsive, smart structural nanocomposites that self-predict upcoming fracture.« less

Experimental and numerical investigation of the nonlinear dynamics of compliant mechanisms for deployable structures

NASA Astrophysics Data System (ADS)

Dewalque, Florence; Schwartz, Cédric; Denoël, Vincent; Croisier, Jean-Louis; Forthomme, Bénédicte; Brüls, Olivier

2018-02-01

This paper studies the dynamics of tape springs which are characterised by a highly geometrical nonlinear behaviour including buckling, the formation of folds and hysteresis. An experimental set-up is designed to capture these complex nonlinear phenomena. The experimental data are acquired by the means of a 3D motion analysis system combined with a synchronised force plate. Deployment tests show that the motion can be divided into three phases characterised by different types of folds, frequencies of oscillation and damping behaviours. Furthermore, the reproducibility quality of the dynamic and quasi-static results is validated by performing a large number of tests. In parallel, a nonlinear finite element model is developed. The required model parameters are identified based on simple experimental tests such as static deformed configurations and small amplitude vibration tests. In the end, the model proves to be well correlated with the experimental results in opposite sense bending, while in equal sense, both the experimental set-up and the numerical model are particularly sensitive to the initial conditions.

Internal viscoelastic loading in cat papillary muscle.

PubMed Central

Chiu, Y L; Ballou, E W; Ford, L E

1982-01-01

The passive mechanical properties of myocardium were defined by measuring force responses to rapid length ramps applied to unstimulated cat papillary muscles. The immediate force changes following these ramps recovered partially to their initial value, suggesting a series combination of viscous element and spring. Because the stretched muscle can bear force at rest, the viscous element must be in parallel with an additional spring. The instantaneous extension-force curves measured at different lengths were nonlinear, and could be made to superimpose by a simple horizontal shift. This finding suggests that the same spring was being measured at each length, and that this spring was in series with both the viscous element and its parallel spring (Voigt configuration), so that the parallel spring is held nearly rigid by the viscous element during rapid steps. The series spring in the passive muscle could account for most of the series elastic recoil in the active muscle, suggesting that the same spring is in series with both the contractile elements and the viscous element. It is postulated that the viscous element might be coupled to the contractile elements by a compliance, so that the load imposed on the contractile elements by the passive structures is viscoelastic rather than purely viscous. Such a viscoelastic load would give the muscle a length-independent, early diastolic restoring force. The possibility is discussed that the length-independent restoring force would allow some of the energy liberated during active shortening to be stored and released during relaxation. Images FIGURE 7 FIGURE 8 PMID:7171707

Unsteady Aerodynamic Force Sensing from Measured Strain

NASA Technical Reports Server (NTRS)

Pak, Chan-Gi

2016-01-01

A simple approach for computing unsteady aerodynamic forces from simulated measured strain data is proposed in this study. First, the deflection and slope of the structure are computed from the unsteady strain using the two-step approach. Velocities and accelerations of the structure are computed using the autoregressive moving average model, on-line parameter estimator, low-pass filter, and a least-squares curve fitting method together with analytical derivatives with respect to time. Finally, aerodynamic forces over the wing are computed using modal aerodynamic influence coefficient matrices, a rational function approximation, and a time-marching algorithm. A cantilevered rectangular wing built and tested at the NASA Langley Research Center (Hampton, Virginia, USA) in 1959 is used to validate the simple approach. Unsteady aerodynamic forces as well as wing deflections, velocities, accelerations, and strains are computed using the CFL3D computational fluid dynamics (CFD) code and an MSC/NASTRAN code (MSC Software Corporation, Newport Beach, California, USA), and these CFL3D-based results are assumed as measured quantities. Based on the measured strains, wing deflections, velocities, accelerations, and aerodynamic forces are computed using the proposed approach. These computed deflections, velocities, accelerations, and unsteady aerodynamic forces are compared with the CFL3D/NASTRAN-based results. In general, computed aerodynamic forces based on the lifting surface theory in subsonic speeds are in good agreement with the target aerodynamic forces generated using CFL3D code with the Euler equation. Excellent aeroelastic responses are obtained even with unsteady strain data under the signal to noise ratio of -9.8dB. The deflections, velocities, and accelerations at each sensor location are independent of structural and aerodynamic models. Therefore, the distributed strain data together with the current proposed approaches can be used as distributed deflection, velocity, and acceleration sensors. This research demonstrates the feasibility of obtaining induced drag and lift forces through the use of distributed sensor technology with measured strain data. An active induced drag control system thus can be designed using the two computed aerodynamic forces, induced drag and lift, to improve the fuel efficiency of an aircraft. Interpolation elements between structural finite element grids and the CFD grids and centroids are successfully incorporated with the unsteady aeroelastic computation scheme. The most critical technology for the success of the proposed approach is the robust on-line parameter estimator, since the least-squares curve fitting method depends heavily on aeroelastic system frequencies and damping factors.

Estimates of the dissipative heat and axial torque generated by ocean tides on icy satellites in the outer solar system.

NASA Astrophysics Data System (ADS)

Tyler, R.

2012-09-01

The tidal flow response generated in a satellite ocean depends strongly on the ocean configuration parameters as these parameters control the form and frequencies of the ocean's natural modes of oscillation; if there is a near match between the form and frequency of one of these natural modes and that of one of the available tidal forcing constituents, the ocean can be resonantly excited, producing a strong tidal response. The fundamental elements of the response are described by the tidal flow and surface fluctuations. Derivative elements of the response include the associated dissipative heat, stress, and forces/torques. The dissipative heat has received much previous attention as it may be important in explaining the heat budget on several of the satellites in the Outer Solar System. While these estimates will be reviewed and compared with the tidal dissipation estimates compiled in Hussman et al. (2010), the primary goal in this presentation is to extend the analysis to consider the tidally generated axial torque on the satellites and the potential consquences for rotation. Interestingly, even a synchronously rotating satellite will, if a global fluid layer is included, experience a complex set of opportunities for torques in both the prograde and retrograde sense. The amplitude and sense of the torque sensitively depends on the ocean parameters controlling the tidal response. This sensitivity, combined with expected feedbacks whereby the tides affect the orbital parameters, suggests that the evolution of the satellite system will experience phases of both prograde and retrograde tidal torques during its evolution. A related point is that parameters of the ocean might be inferred from inferences or observations of torque or rotational deviations. In the panels to the right we show the nondimensional tidal torques associated with obliquity (top) and eccentricity (bottom). The parameters described in the labeling are the fluid density ρ, surface gravity g, ocean surface area A, tidal equilibrium height ηF, dissipation quality factor Q,and c=(gh)1/2, cr=Ωa, with ocean thickness h, rotation rate Ω, and radius a. Torque due to tides forced by obliquity as a function of the parameters c/cr and Q. Retrograde ("Westward") and prograde ("Eastward") components shown in left and right panels, respectively. Log10 scale shown in colorbar.

A linear stepping endovascular intervention robot with variable stiffness and force sensing.

PubMed

He, Chengbin; Wang, Shuxin; Zuo, Siyang

2018-05-01

Robotic-assisted endovascular intervention surgery has attracted significant attention and interest in recent years. However, limited designs have focused on the variable stiffness mechanism of the catheter shaft. Flexible catheter needs to be partially switched to a rigid state that can hold its shape against external force to achieve a stable and effective insertion procedure. Furthermore, driving catheter in a similar way with manual procedures has the potential to make full use of the extensive experience from conventional catheter navigation. Besides driving method, force sensing is another significant factor for endovascular intervention. This paper presents a variable stiffness catheterization system that can provide stable and accurate endovascular intervention procedure with a linear stepping mechanism that has a similar operation mode to the conventional catheter navigation. A specially designed shape-memory polymer tube with water cooling structure is used to achieve variable stiffness of the catheter. Hence, four FBG sensors are attached to the catheter tip in order to monitor the tip contact force situation with temperature compensation. Experimental results show that the actuation unit is able to deliver linear and rotational motions. We have shown the feasibility of FBG force sensing to reduce the effect of temperature and detect the tip contact force. The designed catheter can change its stiffness partially, and the stiffness of the catheter can be remarkably increased in rigid state. Hence, in the rigid state, the catheter can hold its shape against a [Formula: see text] load. The prototype has also been validated with a vascular phantom, demonstrating the potential clinical value of the system. The proposed system provides important insights into the design of compact robotic-assisted catheter incorporating effective variable stiffness mechanism and real-time force sensing for intraoperative endovascular intervention.

Shape and Stress Sensing of Multilayered Composite and Sandwich Structures Using an Inverse Finite Element Method

NASA Technical Reports Server (NTRS)

Cerracchio, Priscilla; Gherlone, Marco; Di Sciuva, Marco; Tessler, Alexander

2013-01-01

The marked increase in the use of composite and sandwich material systems in aerospace, civil, and marine structures leads to the need for integrated Structural Health Management systems. A key capability to enable such systems is the real-time reconstruction of structural deformations, stresses, and failure criteria that are inferred from in-situ, discrete-location strain measurements. This technology is commonly referred to as shape- and stress-sensing. Presented herein is a computationally efficient shape- and stress-sensing methodology that is ideally suited for applications to laminated composite and sandwich structures. The new approach employs the inverse Finite Element Method (iFEM) as a general framework and the Refined Zigzag Theory (RZT) as the underlying plate theory. A three-node inverse plate finite element is formulated. The element formulation enables robust and efficient modeling of plate structures instrumented with strain sensors that have arbitrary positions. The methodology leads to a set of linear algebraic equations that are solved efficiently for the unknown nodal displacements. These displacements are then used at the finite element level to compute full-field strains, stresses, and failure criteria that are in turn used to assess structural integrity. Numerical results for multilayered, highly heterogeneous laminates demonstrate the unique capability of this new formulation for shape- and stress-sensing.

Force-sensed interface for control and training space robot

NASA Astrophysics Data System (ADS)

Moiseev, O. S.; Sarsadskikh, A. S.; Povalyaev, N. D.; Gorbunov, V. I.; Kulakov, F. M.; Vasilev, V. V.

2018-05-01

A method of positional and force-torque control of robots is proposed. Prototypes of the system and the master handle have been created. Algorithm of bias estimation and gravity compensation for force-torque sensor and force-torque trajectory correction are described.

32 CFR 806.29 - Administrative processing of Air Force FOIA requests.

Code of Federal Regulations, 2012 CFR

2012-07-01

... section. (c) Contacts with FOIA requesters and non-Air Force submitters of data. (1) Contacts with Air... memoranda documenting requester contacts with Air Force elements regarding a pending FOIA request in the requester's FOIA file. If the requester contacts Air Force elements telephonically about a pending FOIA...

32 CFR 806.29 - Administrative processing of Air Force FOIA requests.

Code of Federal Regulations, 2011 CFR

2011-07-01

... section. (c) Contacts with FOIA requesters and non-Air Force submitters of data. (1) Contacts with Air... memoranda documenting requester contacts with Air Force elements regarding a pending FOIA request in the requester's FOIA file. If the requester contacts Air Force elements telephonically about a pending FOIA...

32 CFR 806.29 - Administrative processing of Air Force FOIA requests.

Code of Federal Regulations, 2014 CFR

2014-07-01

... section. (c) Contacts with FOIA requesters and non-Air Force submitters of data. (1) Contacts with Air... memoranda documenting requester contacts with Air Force elements regarding a pending FOIA request in the requester's FOIA file. If the requester contacts Air Force elements telephonically about a pending FOIA...

Microstructure actuation and gas sensing by the Knudsen thermal force

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

Strongrich, Andrew; Alexeenko, Alina, E-mail: alexeenk@purdue.edu

2015-11-09

The generation of forces and moments on structures immersed in rarefied non-isothermal gas flows has received limited practical implementation since first being discovered over a century ago. The formation of significant thermal stresses requires both large thermal gradients and characteristic dimensions which are comparable to the gas molecular mean free path. For macroscopic geometries, this necessitates impractically high temperatures and very low pressures. At the microscale, however, these conditions are easily achieved, allowing the effects to be exploited, namely, for gas-property sensing and microstructure actuation. In this letter, we introduce and experimentally evaluate performance of a microelectromechanical in-plane Knudsen radiometricmore » actuator, a self-contained device having Knudsen thermal force generation, sensing, and tuning mechanisms integrated onto the same platform. Sensitivity to ambient pressure, temperature gradient, as well as gas composition is demonstrated. Results are presented in terms of a non-dimensional force coefficient, allowing measurements to be directly compared to the previous experimental and computational data on out-of-plane cantilevered configurations.« less

Multi-Axis Force Sensor for Human-Robot Interaction Sensing in a Rehabilitation Robotic Device.

PubMed

Grosu, Victor; Grosu, Svetlana; Vanderborght, Bram; Lefeber, Dirk; Rodriguez-Guerrero, Carlos

2017-06-05

Human-robot interaction sensing is a compulsory feature in modern robotic systems where direct contact or close collaboration is desired. Rehabilitation and assistive robotics are fields where interaction forces are required for both safety and increased control performance of the device with a more comfortable experience for the user. In order to provide an efficient interaction feedback between the user and rehabilitation device, high performance sensing units are demanded. This work introduces a novel design of a multi-axis force sensor dedicated for measuring pelvis interaction forces in a rehabilitation exoskeleton device. The sensor is conceived such that it has different sensitivity characteristics for the three axes of interest having also movable parts in order to allow free rotations and limit crosstalk errors. Integrated sensor electronics make it easy to acquire and process data for a real-time distributed system architecture. Two of the developed sensors are integrated and tested in a complex gait rehabilitation device for safe and compliant control.

Oscillatory motion based measurement method and sensor for measuring wall shear stress due to fluid flow

DOEpatents

Armstrong, William D [Laramie, WY; Naughton, Jonathan [Laramie, WY; Lindberg, William R [Laramie, WY

2008-09-02

A shear stress sensor for measuring fluid wall shear stress on a test surface is provided. The wall shear stress sensor is comprised of an active sensing surface and a sensor body. An elastic mechanism mounted between the active sensing surface and the sensor body allows movement between the active sensing surface and the sensor body. A driving mechanism forces the shear stress sensor to oscillate. A measuring mechanism measures displacement of the active sensing surface relative to the sensor body. The sensor may be operated under periodic excitation where changes in the nature of the fluid properties or the fluid flow over the sensor measurably changes the amplitude or phase of the motion of the active sensing surface, or changes the force and power required from a control system in order to maintain constant motion. The device may be operated under non-periodic excitation where changes in the nature of the fluid properties or the fluid flow over the sensor change the transient motion of the active sensor surface or change the force and power required from a control system to maintain a specified transient motion of the active sensor surface.

Functional Relationship between Skull Form and Feeding Mechanics in Sphenodon, and Implications for Diapsid Skull Development

PubMed Central

Curtis, Neil; Jones, Marc E. H.; Shi, Junfen; O'Higgins, Paul; Evans, Susan E.; Fagan, Michael J.

2011-01-01

The vertebrate skull evolved to protect the brain and sense organs, but with the appearance of jaws and associated forces there was a remarkable structural diversification. This suggests that the evolution of skull form may be linked to these forces, but an important area of debate is whether bone in the skull is minimised with respect to these forces, or whether skulls are mechanically “over-designed” and constrained by phylogeny and development. Mechanical analysis of diapsid reptile skulls could shed light on this longstanding debate. Compared to those of mammals, the skulls of many extant and extinct diapsids comprise an open framework of fenestrae (window-like openings) separated by bony struts (e.g., lizards, tuatara, dinosaurs and crocodiles), a cranial form thought to be strongly linked to feeding forces. We investigated this link by utilising the powerful engineering approach of multibody dynamics analysis to predict the physiological forces acting on the skull of the diapsid reptile Sphenodon. We then ran a series of structural finite element analyses to assess the correlation between bone strain and skull form. With comprehensive loading we found that the distribution of peak von Mises strains was particularly uniform throughout the skull, although specific regions were dominated by tensile strains while others were dominated by compressive strains. Our analyses suggest that the frame-like skulls of diapsid reptiles are probably optimally formed (mechanically ideal: sufficient strength with the minimal amount of bone) with respect to functional forces; they are efficient in terms of having minimal bone volume, minimal weight, and also minimal energy demands in maintenance. PMID:22216358

An actuated force feedback-enabled laparoscopic instrument for robotic-assisted surgery.

PubMed

Moradi Dalvand, Mohsen; Shirinzadeh, Bijan; Shamdani, Amir Hossein; Smith, Julian; Zhong, Yongmin

2014-03-01

Robotic-assisted minimally invasive surgery systems not only have the advantages of traditional laparoscopic instruments but also have other important advantages, including restoring the surgeon's hand-eye coordination and improving the surgeon's precision by filtering hand tremors. Unfortunately, these benefits have come at the expense of the surgeon's ability to feel. Various solutions for restoring this feature have been proposed. An actuated modular force feedback-enabled laparoscopic instrument was proposed that is able to measure tip-tissue lateral interaction forces as well as normal grasping forces. The instrument has also the capability to adjust the grasping direction inside the patient body. In order to measure the interaction forces, strain gauges were employed. A series of finite element analyses were performed to gain an understanding of the actual magnitude of surface strains where gauges are applied. The strain gauge bridge configurations were calibrated. A series of experiments was conducted and the results were analysed. The modularity feature of the proposed instrument makes it interchangeable between various tip types of different functionalities (e.g. cutter, grasper, dissector). Calibration results of the strain gauges incorporated into the tube and at the base of the instrument presented the monotonic responses for these strain gauge configurations. Experimental results from tissue probing and tissue characterization experiments verified the capability of the proposed instrument in measuring lateral probing forces and characterizing artificial tissue samples of varying stiffness. The proposed instrument can improve the quality of palpation and characterization of soft tissues of varying stiffness by restoring sense of touch in robotic assisted minimally invasive surgery operations. Copyright © 2013 John Wiley & Sons, Ltd.

Design of a haptic device with grasp and push-pull force feedback for a master-slave surgical robot.

PubMed

Hu, Zhenkai; Yoon, Chae-Hyun; Park, Samuel Byeongjun; Jo, Yung-Ho

2016-07-01

We propose a portable haptic device providing grasp (kinesthetic) and push-pull (cutaneous) sensations for optical-motion-capture master interfaces. Although optical-motion-capture master interfaces for surgical robot systems can overcome the stiffness, friction, and coupling problems of mechanical master interfaces, it is difficult to add haptic feedback to an optical-motion-capture master interface without constraining the free motion of the operator's hands. Therefore, we utilized a Bowden cable-driven mechanism to provide the grasp and push-pull sensation while retaining the free hand motion of the optical-motion capture master interface. To evaluate the haptic device, we construct a 2-DOF force sensing/force feedback system. We compare the sensed force and the reproduced force of the haptic device. Finally, a needle insertion test was done to evaluate the performance of the haptic interface in the master-slave system. The results demonstrate that both the grasp force feedback and the push-pull force feedback provided by the haptic interface closely matched with the sensed forces of the slave robot. We successfully apply our haptic interface in the optical-motion-capture master-slave system. The results of the needle insertion test showed that our haptic feedback can provide more safety than merely visual observation. We develop a suitable haptic device to produce both kinesthetic grasp force feedback and cutaneous push-pull force feedback. Our future research will include further objective performance evaluations of the optical-motion-capture master-slave robot system with our haptic interface in surgical scenarios.

Remote sensing monitoring and driving force analysis to forest and greenbelt in Zhuhai

NASA Astrophysics Data System (ADS)

Yuliang Qiao, Pro.

As an important city in the southern part of Chu Chiang Delta, Zhuhai is one of the four special economic zones which are opening up to the outside at the earliest in China. With pure and fresh air and trees shading the street, Zhuhai is a famous beach port city which is near the mountain and by the sea. On the basis of Garden City, the government of Zhuhai decides to build National Forest City in 2011, which firstly should understand the situation of greenbelt in Zhuhai in short term. Traditional methods of greenbelt investigation adopt the combination of field surveying and statistics, whose efficiency is low and results are not much objective because of artificial influence. With the adventure of the information technology such as remote sensing to earth observation, especially the launch of many remote sensing satellites with high resolution for the past few years, kinds of urban greenbelt information extraction can be carried out by using remote sensing technology; and dynamic monitoring to spatial pattern evolvement of forest and greenbelt in Zhuhai can be achieved by the combination of remote sensing and GIS technology. Taking Landsat5 TM data in 1995, Landsat7 ETM+ data in 2002, CCD and HR data of CBERS-02B in 2009 as main information source, this research firstly makes remote sensing monitoring to dynamic change of forest and greenbelt in Zhuhai by using the combination of vegetation coverage index and three different information extraction methods, then does a driving force analysis to the dynamic change results in 3 months. The results show: the forest area in Zhuhai shows decreasing tendency from 1995 to 2002, increasing tendency from 2002 to 2009; overall, the forest area show a small diminution tendency from 1995 to 2009. Through the comparison to natural and artificial driving force, the artificial driving force is the leading factor to the change of forest and greenbelt in Zhuhai. The research results provide a timely and reliable scientific basis for the Zhuhai Government in building National Forest City. Keywords: forest and greenbelt; remote sensing; dynamic monitoring; driving force; vegetation coverage

Global versus local mechanisms of temperature sensing in ion channels.

PubMed

Arrigoni, Cristina; Minor, Daniel L

2018-05-01

Ion channels turn diverse types of inputs, ranging from neurotransmitters to physical forces, into electrical signals. Channel responses to ligands generally rely on binding to discrete sensor domains that are coupled to the portion of the channel responsible for ion permeation. By contrast, sensing physical cues such as voltage, pressure, and temperature arises from more varied mechanisms. Voltage is commonly sensed by a local, domain-based strategy, whereas the predominant paradigm for pressure sensing employs a global response in channel structure to membrane tension changes. Temperature sensing has been the most challenging response to understand and whether discrete sensor domains exist for pressure and temperature has been the subject of much investigation and debate. Recent exciting advances have uncovered discrete sensor modules for pressure and temperature in force-sensitive and thermal-sensitive ion channels, respectively. In particular, characterization of bacterial voltage-gated sodium channel (BacNa V ) thermal responses has identified a coiled-coil thermosensor that controls channel function through a temperature-dependent unfolding event. This coiled-coil thermosensor blueprint recurs in other temperature sensitive ion channels and thermosensitive proteins. Together with the identification of ion channel pressure sensing domains, these examples demonstrate that "local" domain-based solutions for sensing force and temperature exist and highlight the diversity of both global and local strategies that channels use to sense physical inputs. The modular nature of these newly discovered physical signal sensors provides opportunities to engineer novel pressure-sensitive and thermosensitive proteins and raises new questions about how such modular sensors may have evolved and empowered ion channel pores with new sensibilities.

Remote Sensing as a Landscape Epidemiologic Tool to Identify Villages at High Risk for Malaria Transmission

NASA Technical Reports Server (NTRS)

Beck, Louisa R.; Rodriquez, Mario H.; Dister, Sheri W.; Rodriquez, Americo D.; Rejmankova, Eliska; Ulloa, Armando; Meza, Rosa A.; Roberts, Donald R.; Paris, Jack F.; Spanner, Michael A.;

Packing a pinch: functional implications of chela shapes in scorpions using finite element analysis

PubMed Central

van der Meijden, Arie; Kleinteich, Thomas; Coelho, Pedro

2012-01-01

Scorpions depend on their pedipalps for prey capture, defense, mating and sensing their environment. Some species additionally use their pedipalps for burrowing or climbing. Because the pincers or chelae at the end of the pedipalps vary widely in shape, they have been used as part of a suite of characters to delimit ecomorphotypes. We here evaluate the influence of the different chela cuticular shapes on their performance under natural loading conditions. Chelae of 20 species, representing seven families and spanning most of the range of chela morphologies, were assigned to clusters based on chela shape parameters using hierarchical cluster analysis. Several clusters were identified corresponding approximately to described scorpion ecomorphotypes. Finite element models of the chela cuticulae were constructed from CT scans and loaded with estimated pinch forces based on in vivo force measurements. Chela shape clusters differed significantly in mean Von Mises stress and strain energy. Normalized FEA showed that chela shape significantly influenced Von Mises stress and strain energy in the chela cuticula, with Von Mises stress varying up to an order of magnitude and strain energy up to two orders of magnitude. More elongate, high-aspect ratio chela forms showed significantly higher mean stress compared with more robust low-aspect ratio forms. This suggests that elongate chelae are at a higher risk of failure when operating near the maximum pinch force. Phylogenetic independent contrasts (PIC) were calculated based on a partly resolved phylogram with branch lengths based on an alignment of the 12S, 16S and CO1 mitochondrial genes. PIC showed that cuticular stress and strain in the chela were correlated with several shape parameters, such as aspect ratio, movable finger length, and chela height, independently of phylogenetic history. Our results indicate that slender chela morphologies may be less suitable for high-force functions such as burrowing and defense. Further implications of these findings for the ecology and evolution of the different chela morphologies are discussed. PMID:22360433

On the forces that drive and resist deformation of the south-central Mediterranean: a mechanical model study

NASA Astrophysics Data System (ADS)

Nijholt, Nicolai; Govers, Rob; Wortel, Rinus

2018-04-01

The geodynamics of the Mediterranean comprises a transitional setting in which slab rollback and plate convergence compete to shape the region. In the central Mediterranean, where the balance of driving and resisting forces changes continuously and rapidly since the Miocene, both kinematic and seismo-tectonic observations display a strong variation in deformation style and, therefore possibly, lithospheric forces. We aim to understand the current kinematics in southern Italy and Sicily in terms of lithospheric forces that cause them. The strong regional variation of geodetic velocities appears to prohibit such simple explanation. We use mechanical models to quantify the deformation resulting from large-scale Africa-Eurasia convergence, ESE retreat of the Calabrian subduction zone, pull by the Aegean slab, and regional variations in gravitational potential energy (topography). A key model element is the resistance to slip on major regional fault zones. We show that geodetic velocities, seismicity and sense of slip on regional faults can be understood to result from lithospheric forces. Our most important new finding is that regional variations in resistive tractions are required to fit the observations, with notably very low tractions on the Calabrian subduction contact, and a buildup towards a significant earthquake in the Calabrian fore-arc. We also find that the Calabrian net slab pull force is strongly reduced (compared to the value possible in view of the slab's dimensions) and that trench suction tractions are negligible. Such very small contributions to the present-day force balance in the south-central Mediterranean suggest that the Calabrian arc is now further transitioning towards a setting dominated by Africa-Eurasia plate convergence, whereas during the past 30 Myrs slab retreat continually was the dominant factor.

Improved accuracy for finite element structural analysis via a new integrated force method

NASA Technical Reports Server (NTRS)

Patnaik, Surya N.; Hopkins, Dale A.; Aiello, Robert A.; Berke, Laszlo

1992-01-01

A comparative study was carried out to determine the accuracy of finite element analyses based on the stiffness method, a mixed method, and the new integrated force and dual integrated force methods. The numerical results were obtained with the following software: MSC/NASTRAN and ASKA for the stiffness method; an MHOST implementation method for the mixed method; and GIFT for the integrated force methods. The results indicate that on an overall basis, the stiffness and mixed methods present some limitations. The stiffness method generally requires a large number of elements in the model to achieve acceptable accuracy. The MHOST method tends to achieve a higher degree of accuracy for course models than does the stiffness method implemented by MSC/NASTRAN and ASKA. The two integrated force methods, which bestow simultaneous emphasis on stress equilibrium and strain compatibility, yield accurate solutions with fewer elements in a model. The full potential of these new integrated force methods remains largely unexploited, and they hold the promise of spawning new finite element structural analysis tools.

Electromagnetic Contact-Force Sensing Electrophysiological Catheters: How Accurate is the Technology?

PubMed

Bourier, Felix; Hessling, Gabriele; Ammar-Busch, Sonia; Kottmaier, Marc; Buiatti, Alessandra; Grebmer, Christian; Telishevska, Marta; Semmler, Verena; Lennerz, Carsten; Schneider, Christine; Kolb, Christof; Deisenhofer, Isabel; Reents, Tilko

2016-03-01

Contact-force (CF) sensing catheters are increasingly used in clinical electrophysiological practice due to their efficacy and safety profile. As data about the accuracy of this technology are scarce, we sought to quantify accuracy based on in vitro experiments. A custom-made force sensor was constructed that allowed exact force reference measurements registered via a flexible membrane. A Smarttouch Surround Flow (ST SF) ablation catheter (Biosense Webster, Diamond Bar, CA, USA) was brought in contact with the membrane of the force sensor in order to compare the ST SF force measurements to force sensor reference measurements. ST SF force sensing technology is based on deflection registration between the distal and proximal catheter tip. The experiment was repeated for n = 10 ST SF catheters, which showed no significant difference in accuracy levels. A series of measurements (n = 1200) was carried out for different angles of force acting to the catheter tip (0°/perpendicular contact, 30°, 60°, 90°/parallel contact). The mean absolute differences between reference and ST SF measurements were 1.7 ± 1.8 g (0°), 1.6 ± 1.2 g (30°), 1.4 ± 1.3 g (60°), and 6.6 ± 5.9 g (90°). Measurement accuracy was significantly higher in non-parallel contact when compared with parallel contact (P < 0.01). Catheter force measurements using the ST SF catheters show a high level of accuracy regarding differences to reference measurements and reproducibility. The reduced accuracy in measurements of 90° acting forces (parallel contact) might be clinically important when creating, for example, linear lesions. © 2015 Wiley Periodicals, Inc.

Force Structure: Better Information Needed to Support Air Force A-10 and Other Future Divestment Decisions

DTIC Science & Technology

2016-08-01

estimate should have a standardized structure that breaks costs into discrete elements with sufficient detail to ensure that cost elements are...FORCE STRUCTURE Better Information Needed to Support Air Force A-10 and Other Future Divestment Decisions Report...Accountability Office Highlights of GAO-16-816, a report to congressional committees August 2016 FORCE STRUCTURE Better Information Needed to Support

The inverse problem of sensing the mass and force induced by an adsorbate on a beam nanomechanical resonator

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

Liu, Yun; Zhang, Yin

2016-06-08

The mass sensing superiority of a micro/nanomechanical resonator sensor over conventional mass spectrometry has been, or at least, is being firmly established. Because the sensing mechanism of a mechanical resonator sensor is the shifts of resonant frequencies, how to link the shifts of resonant frequencies with the material properties of an analyte formulates an inverse problem. Besides the analyte/adsorbate mass, many other factors such as position and axial force can also cause the shifts of resonant frequencies. The in-situ measurement of the adsorbate position and axial force is extremely difficult if not impossible, especially when an adsorbate is as smallmore » as a molecule or an atom. Extra instruments are also required. In this study, an inverse problem of using three resonant frequencies to determine the mass, position and axial force is formulated and solved. The accuracy of the inverse problem solving method is demonstrated and how the method can be used in the real application of a nanomechanical resonator is also discussed. Solving the inverse problem is helpful to the development and application of mechanical resonator sensor on two things: reducing extra experimental equipments and achieving better mass sensing by considering more factors.« less

WaterSense Specification for Showerheads Supporting Statement

EPA Pesticide Factsheets

WaterSense collaborated with the American Society of Mechanical Engineers (ASME)/Canadian Standards Association (CSA) Joint Harmonization Task Force to develop the specification criteria for high-efficiency showerheads.

Design and Validation of a 150 MHz HFFQCM Sensor for Bio-Sensing Applications

PubMed Central

Fernández, Román; García, Pablo; García, María; Jiménez, Yolanda; Arnau, Antonio

2017-01-01

Acoustic wave resonators have become suitable devices for a broad range of sensing applications due to their sensitivity, low cost, and integration capability, which are all factors that meet the requirements for the resonators to be used as sensing elements for portable point of care (PoC) platforms. In this work, the design, characterization, and validation of a 150 MHz high fundamental frequency quartz crystal microbalance (HFF-QCM) sensor for bio-sensing applications are introduced. Finite element method (FEM) simulations of the proposed design are in good agreement with the electrical characterization of the manufactured resonators. The sensor is also validated for bio-sensing applications. For this purpose, a specific sensor cell was designed and manufactured that addresses the critical requirements associated with this type of sensor and application. Due to the small sensing area and the sensor’s fragility, these requirements include a low-volume flow chamber in the nanoliter range, and a system approach that provides the appropriate pressure control for assuring liquid confinement while maintaining the integrity of the sensor with a good base line stability and easy sensor replacement. The sensor characteristics make it suitable for consideration as the elemental part of a sensor matrix in a multichannel platform for point of care applications. PMID:28885551

Novel Door-opening Method for Six-legged Robots Based on Only Force Sensing

NASA Astrophysics Data System (ADS)

Chen, Zhi-Jun; Gao, Feng; Pan, Yang

2017-09-01

Current door-opening methods are mainly developed on tracked, wheeled and biped robots by applying multi-DOF manipulators and vision systems. However, door-opening methods for six-legged robots are seldom studied, especially using 0-DOF tools to operate and only force sensing to detect. A novel door-opening method for six-legged robots is developed and implemented to the six-parallel-legged robot. The kinematic model of the six-parallel-legged robot is established and the model of measuring the positional relationship between the robot and the door is proposed. The measurement model is completely based on only force sensing. The real-time trajectory planning method and the control strategy are designed. The trajectory planning method allows the maximum angle between the sagittal axis of the robot body and the normal line of the door plane to be 45º. A 0-DOF tool mounted to the robot body is applied to operate. By integrating with the body, the tool has 6 DOFs and enough workspace to operate. The loose grasp achieved by the tool helps release the inner force in the tool. Experiments are carried out to validate the method. The results show that the method is effective and robust in opening doors wider than 1 m. This paper proposes a novel door-opening method for six-legged robots, which notably uses a 0-DOF tool and only force sensing to detect and open the door.

Force Sensing Resistor (FSR): a brief overview and the low-cost sensor for active compliance control

NASA Astrophysics Data System (ADS)

Sadun, A. S.; Jalani, J.; Sukor, J. A.

2016-07-01

Force Sensing Resistors (FSR) sensors are devices that allow measuring static and dynamic forces applied to a contact surface. Their range of responses is basically depending on the variation of its electric resistance. In general, Flexiforce and Interlink are two common types of FSR sensors that are available, cheap and easily found in the market. Studies have shown that the FSR sensors are usually applied for robotic grippers and for biomechanical fields. This paper provides a brief overview of the application of the FSR sensors. Subsequently, two different set of experiments are carried out to test the effectiveness of the Flexiforce and Interlink sensors. First, the hardness detector system (Case Study A) and second, the force-position control system (Case Study B). The hardware used for the experiment was developed from low-cost materials. The results revealed that both FSR sensors are sufficient and reliable to provide a good sensing modality particularly for measuring force. Apart from the low-cost sensors, essentially, the FSR sensors are very useful devices that able to provide a good active compliance control, particularly for the grasping robotic hand.

Electronic gap sensor and method

DOEpatents

Williams, R.S.; King, E.L.; Campbell, S.L.

1991-08-06

Disclosed are an apparatus and method for regulating the gap between a casting nozzle and a casting wheel in which the gap between the casting nozzle and the casting wheel is monitored by means of at least one sensing element protruding from the face of the casting nozzle. The sensing element is preferably connected to a voltage source and the casting wheel grounded. When the sensing element contacts the casting wheel, an electric circuit is completed. The completion of the circuit can be registered by an indicator, and the presence or absence of a completed circuit indicates the relative position of the casting nozzle to the casting wheel. The relative positions of the casting nozzle and casting wheel can thereby be selectively adjusted to continually maintain a predetermined distance between their adjacent surfaces. 5 figures.

Pressure sensor

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

Mee, David K.; Ripley, Edward B.; Nienstedt, Zachary C.

Disclosed is a passive, in-situ pressure sensor. The sensor includes a sensing element having a ferromagnetic metal and a tension inducing mechanism coupled to the ferromagnetic metal. The tension inducing mechanism is operable to change a tensile stress upon the ferromagnetic metal based on a change in pressure in the sensing element. Changes in pressure are detected based on changes in the magnetic switching characteristics of the ferromagnetic metal when subjected to an alternating magnetic field caused by the change in the tensile stress. The sensing element is embeddable in a closed system for detecting pressure changes without the needmore » for any penetrations of the system for power or data acquisition by detecting changes in the magnetic switching characteristics of the ferromagnetic metal caused by the tensile stress.« less

Sensor and methods of detecting target materials and situations in closed systems

DOEpatents

Mee, David K.; Ripley, Edward B.; Nienstedt, Zachary C.; Nienstedt, Alex W.; Howell, Jr., Layton N.

2018-03-13

Disclosed is a passive, in-situ pressure sensor. The sensor includes a sensing element having a ferromagnetic metal and a tension inducing mechanism coupled to the ferromagnetic metal. The tension inducing mechanism is operable to change a tensile stress upon the ferromagnetic metal based on a change in pressure in the sensing element. Changes in pressure are detected based on changes in the magnetic switching characteristics of the ferromagnetic metal when subjected to an alternating magnetic field caused by the change in the tensile stress. The sensing element is embeddable in a closed system for detecting pressure changes without the need for any penetrations of the system for power or data acquisition by detecting changes in the magnetic switching characteristics of the ferromagnetic metal caused by the tensile stress.

Electronic gap sensor and method

DOEpatents

Williams, Robert S.; King, Edward L.; Campbell, Steven L.

1991-01-01

An apparatus and method for regulating the gap between a casting nozzle and a casting wheel in which the gap between the casting nozzle and the casting wheel is monitored by means of at least one sensing element protruding from the face of the casting nozzle. The sensing element is preferably connected to a voltage source and the casting wheel grounded. When the sensing element contacts the casting wheel, an electric circuit is completed. The completion of the circuit can be registered by an indicator, and the presence or absence of a completed circuit indicates the relative position of the casting nozzle to the casting wheel. The relative positions of the casting nozzle and casting wheel can thereby be selectively adjusted to continually maintain a predetermined distance between their adjacent surfaces.

High Resolution Quantification of Cellular Forces for Rigidity Sensing

NASA Astrophysics Data System (ADS)

Liu, Shuaimin

This thesis describes a comprehensive study of understanding the mechanism of rigidity sensing by quantitative analysis using submicron pillar array substrates. From mechanobiology perspective, we explore and study molecular pathways involved in rigidity and force sensing at cell-matrix adhesions with regard to cancer, regeneration, and development by quantification methods. In Chapter 2 and 3, we developed fabrication and imaging techniques to enhance the performance of a submicron pillar device in terms of spatial and temporal measurement ability, and we discovered a correlation of rigidity sensing forces and corresponding proteins involved in the early rigidity sensing events. In Chapter 2, we introduced optical effect arising from submicron structure imaging, and we described a technique to identify the correct focal plane of pillar tip by fabricating a substrate with designed-offset pillars. From calibration result, we identified the correct focal plane that was previously overlooked, and verified our findings by other imaging techniques. In Chapter 3, we described several techniques to selectively functionalize elastomeric pillars top and compared these techniques in terms of purposes and fabrication complexity. Techniques introduced in this chapter included direct labeling, such as stamping of fluorescent substances (organic dye, nano-diamond, q-dot) to pillars top, as well as indirect labeling that selectively modify the surface of molds with either metal or fluorescent substances. In Chapter 4, we examined the characteristics of local contractility forces and identified the components formed a sarcomere like contractile unit (CU) that cells use to sense rigidity. CUs were found to be assembled at cell edge, contain myosin II, alpha-actinin, tropomodulin and tropomyosin (Tm), and resemble sarcomeres in size (˜2 mum) and function. Then we performed quantitative analysis of CUs to evaluate rigidity sensing activity over ˜8 hours time course and found that density of CUs decrease with time after spreading on stiff substrate. However addition of EGF dramatically increased local contraction activity such that about 30% of the total contractility was in the contraction units. This stimulatory effect was only observed on stiff substrate not on soft. Moreover, we find that in the early interactions of cells with rigid substrates that EGFR activity is needed for normal spreading and the assembly of local contraction units in media lacking serum and any soluble EGF. In Chapter 5, we performed high temporal- and spatial-resolution tracking of contractile forces exerted by cells on sub-micron elastomeric pillars. We found that actomyosin-based sarcomere-like CUs simultaneously moved opposing pillars in net steps of ˜2.5 nm, independent of rigidity. What correlated with rigidity was the number of steps taken to reach a force level that activated recruitment of alpha-actinin to the CUs. When we removed actomyosin restriction by depleting tropomyosin 2.1, we observed larger steps and higher forces that resulted in aberrant rigidity sensing and growth of non-transformed cells on soft matrices. Thus, we conclude that tropomyosin 2.1 acts as a suppressor of growth on soft matrices by supporting proper rigidity sensing.

How to identify water from thickener aqueous solutions by touch.

PubMed

Nonomura, Yoshimune; Miura, Taku; Miyashita, Takaaki; Asao, Yuka; Shirado, Hirokazu; Makino, Yasutoshi; Maeno, Takashi

2012-06-07

Water detection is one of the most crucial psychological processes for many animals. However, nobody knows the perception mechanism of water through our tactile sense. In the present study, we found that a characteristic frictional stimulus with large acceleration is one of the cues to differentiate water from water contaminated with thickener. When subjects applied small amounts of water to a glass plate, strong stick-slip phenomena with a friction force of 0.46 ± 0.30 N and a vertical force of 0.57 ± 0.36 N were observed at the skin surface, as shown in previous studies. Surprisingly, periodic shears with acceleration seven times greater than gravitational acceleration occurred during the application process. Finite-element analyses predicted that these strong stimuli could activate tactile receptors: Meissner's corpuscle and Pacinians. When such stimuli were applied to the fingertips by an ultrasonic vibrator, a water-like tactile texture was perceived by some subjects, even though no liquid was present between the fingertip and the vibrator surface. These findings could potentially be applied in the following areas: materials science, information technology, medical treatment and entertainment.

How to identify water from thickener aqueous solutions by touch

PubMed Central

Nonomura, Yoshimune; Miura, Taku; Miyashita, Takaaki; Asao, Yuka; Shirado, Hirokazu; Makino, Yasutoshi; Maeno, Takashi

2012-01-01

Water detection is one of the most crucial psychological processes for many animals. However, nobody knows the perception mechanism of water through our tactile sense. In the present study, we found that a characteristic frictional stimulus with large acceleration is one of the cues to differentiate water from water contaminated with thickener. When subjects applied small amounts of water to a glass plate, strong stick-slip phenomena with a friction force of 0.46 ± 0.30 N and a vertical force of 0.57 ± 0.36 N were observed at the skin surface, as shown in previous studies. Surprisingly, periodic shears with acceleration seven times greater than gravitational acceleration occurred during the application process. Finite-element analyses predicted that these strong stimuli could activate tactile receptors: Meissner's corpuscle and Pacinians. When such stimuli were applied to the fingertips by an ultrasonic vibrator, a water-like tactile texture was perceived by some subjects, even though no liquid was present between the fingertip and the vibrator surface. These findings could potentially be applied in the following areas: materials science, information technology, medical treatment and entertainment. PMID:22072449

Chemical Sensing Using Fiber Cavity Ring-Down Spectroscopy

PubMed Central

Waechter, Helen; Litman, Jessica; Cheung, Adrienne H.; Barnes, Jack A.; Loock, Hans-Peter

2010-01-01

Waveguide-based cavity ring-down spectroscopy (CRD) can be used for quantitative measurements of chemical concentrations in small amounts of liquid, in gases or in films. The change in ring-down time can be correlated to analyte concentration when using fiber optic sensing elements that change their attenuation in dependence of either sample absorption or refractive index. Two types of fiber cavities, i.e., fiber loops and fiber strands containing reflective elements, are distinguished. Both types of cavities were coupled to a variety of chemical sensor elements, which are discussed and compared. PMID:22294895

Method and Apparatus for Characterizing Pressure Sensors using Modulated Light Beam Pressure

NASA Technical Reports Server (NTRS)

Youngquist, Robert C. (Inventor)

2003-01-01

Embodiments of apparatuses and methods are provided that use light sources instead of sound sources for characterizing and calibrating sensors for measuring small pressures to mitigate many of the problems with using sound sources. In one embodiment an apparatus has a light source for directing a beam of light on a sensing surface of a pressure sensor for exerting a force on the sensing surface. The pressure sensor generates an electrical signal indicative of the force exerted on the sensing surface. A modulator modulates the beam of light. A signal processor is electrically coupled to the pressure sensor for receiving the electrical signal.

Design and finite element modeling of a novel optical microsystems-based tactile sensor for minimal invasive robotic surgery

NASA Astrophysics Data System (ADS)

Ghanbari Mardasi, Amir; Ghanbari, Mahmood; Salmani Tehrani, Mehdi

2014-09-01

Although recently Minimal Invasive Robotic Surgery (MIRS) has been more addressed because of its wide range of benefits, however there are still some limitations in this regard. In order to address the shortcomings of MIRS systems, various types of tactile sensors with different sensing principles have been presented in the last few years. In the present paper a MEMS-based optical sensor, which has been recently proposed by researchers, is investigated using numerical simulation. By this type of sensors real time quantification of both dynamic and statics contact forces between the tissue and surgical instrument would be possible. The presented sensor has one moving part and works based on the intensity modulation principle of optical fibers. It is electrically-passive, MRI-compatible and it is possible to be fabricated using available standard micro fabrication techniques. The behavior of the sensor has been simulated using COMSOL MULTIPHYSICS 3.5 software. Stress analysis is conducted on the sensor to assess the deflection of the moving part of the sensor due to applied force. The optical simulation is then conducted to estimate the power loss due to the moving part deflection. Using FEM modeling, the relation between force and deflection is derived which is necessary for the calibration of the sensor.

Spring constant measurement using a MEMS force and displacement sensor utilizing paralleled piezoresistive cantilevers

NASA Astrophysics Data System (ADS)

Kohyama, Sumihiro; Takahashi, Hidetoshi; Yoshida, Satoru; Onoe, Hiroaki; Hirayama-Shoji, Kayoko; Tsukagoshi, Takuya; Takahata, Tomoyuki; Shimoyama, Isao

2018-04-01

This paper reports on a method to measure a spring constant on site using a micro electro mechanical systems (MEMS) force and displacement sensor. The proposed sensor consists of a force-sensing cantilever and a displacement-sensing cantilever. Each cantilever is composed of two beams with a piezoresistor on the sidewall for measuring the in-plane lateral directional force and displacement. The force resolution and displacement resolution of the fabricated sensor were less than 0.8 µN and 0.1 µm, respectively. We measured the spring constants of two types of hydrogel microparticles to demonstrate the effectiveness of the proposed sensor, with values of approximately 4.3 N m-1 and 15.1 N m-1 obtained. The results indicated that the proposed sensor is effective for on-site spring constant measurement.

Remote Sensing in Latin America: Technology and Markets for the 1980s

DTIC Science & Technology

1981-08-01

A review is made on the impact of satellite derived remote sensing data in Latin America. Data availability has generated a phenomenal growth in the...The international institutionalization of remote sensing interests in the area is an indicator submitted as a viable force in the continued, future

Nitride-Based Materials for Flexible MEMS Tactile and Flow Sensors in Robotics

PubMed Central

Abels, Claudio; Mastronardi, Vincenzo Mariano; Guido, Francesco; Dattoma, Tommaso; Qualtieri, Antonio; Megill, William M.; De Vittorio, Massimo; Rizzi, Francesco

2017-01-01

The response to different force load ranges and actuation at low energies is of considerable interest for applications of compliant and flexible devices undergoing large deformations. We present a review of technological platforms based on nitride materials (aluminum nitride and silicon nitride) for the microfabrication of a class of flexible micro-electro-mechanical systems. The approach exploits the material stress differences among the constituent layers of nitride-based (AlN/Mo, SixNy/Si and AlN/polyimide) mechanical elements in order to create microstructures, such as upwardly-bent cantilever beams and bowed circular membranes. Piezoresistive properties of nichrome strain gauges and direct piezoelectric properties of aluminum nitride can be exploited for mechanical strain/stress detection. Applications in flow and tactile sensing for robotics are described. PMID:28489040

Effects of stick dynamics on helicopter flying qualities

NASA Technical Reports Server (NTRS)

Watson, Douglas C.; Schroeder, Jeffery A.

1990-01-01

An experiment that investigated the influence of typical helicopter force-feel system dynamics on roll-axis handling qualities was conducted in concurrent ground and inflight simulations. Variations in lateral control natural frequency and damping ratio, effected by changes in inertia and damping, were evaluated in a disturbance-rejection task. Pilot ratings indicated a preference for low-inertia feel systems, although measured performance was relatively constant over the range of stick characteristics. Force-sensing was compared with position sensing as the input to the control system. Force-sensing improved performance but did not improve pilot ratings. Overall, the results indicated that control-stick dynamics, at least within a reasonable range, did not have a significant effect on pilot-vehicle performance. However, the physical effort required to maintain a desired pilot/manipulator bandwidth became objectionable as the stick inertia increased beyond 5-7 lbm, which was reflected in the pilot ratings and comments.

Ultrathin gas permeable oxide membranes for chemical sensing: Nanoporous Ta 2O 5 test study

DOE PAGES

Imbault, Alexander; Wang, Yue; Kruse, Peter; ...

2015-09-25

Conductometric gas sensors made of gas permeable metal oxide ultrathin membranes can combine the functions of a selective filter, preconcentrator, and sensing element and thus can be particularly promising for the active sampling of diluted analytes. Here we report a case study of the electron transport and gas sensing properties of such a membrane made of nanoporous Ta 2O 5. These membranes demonstrated a noticeable chemical sensitivity toward ammonia, ethanol, and acetone at high temperatures above 400 °C. Furthermore, different from traditional thin films, such gas permeable, ultrathin gas sensing elements can be made suspended enabling advanced architectures of ultrasensitivemore » analytical systems operating at high temperatures and in harsh environments.« less

A parametric study of hard tissue injury prediction using finite elements: consideration of geometric complexity, subfailure material properties, CT-thresholding, and element characteristics.

PubMed

Arregui-Dalmases, Carlos; Del Pozo, Eduardo; Duprey, Sonia; Lopez-Valdes, Francisco J; Lau, Anthony; Subit, Damien; Kent, Richard

2010-06-01

The objectives of this study were to examine the axial response of the clavicle under quasistatic compressions replicating the body boundary conditions and to quantify the sensitivity of finite element-predicted fracture in the clavicle to several parameters. Clavicles were harvested from 14 donors (age range 14-56 years). Quasistatic axial compression tests were performed using a custom rig designed to replicate in situ boundary conditions. Prior to testing, high-resolution computed tomography (CT) scans were taken of each clavicle. From those images, finite element models were constructed. Factors varied parametrically included the density used to threshold cortical bone in the CT scans, the presence of trabecular bone, the mesh density, Young's modulus, the maximum stress, and the element type (shell vs. solid, triangular vs. quadrilateral surface elements). The experiments revealed significant variability in the peak force (2.41 +/- 0.72 kN) and displacement to peak force (4.9 +/- 1.1 mm), with age (p < .05) and with some geometrical traits of the specimens. In the finite element models, the failure force and location were moderately dependent upon the Young's modulus. The fracture force was highly sensitive to the yield stress (80-110 MPa). Neither fracture location nor force was strongly dependent on mesh density as long as the element size was less than 5 x 5 mm(2). Both the fracture location and force were strongly dependent upon the threshold density used to define the thickness of the cortical shell.

Polythiophene-fullerene based photodetectors: tuning of spectral response and application in photoluminescence based (bio)chemical sensors.

PubMed

Nalwa, Kanwar S; Cai, Yuankun; Thoeming, Aaron L; Shinar, Joseph; Shinar, Ruth; Chaudhary, Sumit

2010-10-01

A photoluminescence (PL)-based oxygen and glucose sensor utilizing inorganic or organic light emitting diode as the light source, and polythiophene: fullerene type bulk-heterojunction devices as photodetectors, for both intensity and decay-time based monitoring of the sensing element's PL. The sensing element is based on the oxygen-sensitive dye Pt-octaethylporphyrin embedded in a polystyrene matrix.

Sensing magnetic flux density of artificial neurons with a MEMS device.

PubMed

Tapia, Jesus A; Herrera-May, Agustin L; García-Ramírez, Pedro J; Martinez-Castillo, Jaime; Figueras, Eduard; Flores, Amira; Manjarrez, Elías

2011-04-01

We describe a simple procedure to characterize a magnetic field sensor based on microelectromechanical systems (MEMS) technology, which exploits the Lorentz force principle. This sensor is designed to detect, in future applications, the spiking activity of neurons or muscle cells. This procedure is based on the well-known capability that a magnetic MEMS device can be used to sense a small magnetic flux density. In this work, an electronic neuron (FitzHugh-Nagumo) is used to generate controlled spike-like magnetic fields. We show that the magnetic flux density generated by the hardware of this neuron can be detected with a new MEMS magnetic field sensor. This microdevice has a compact resonant structure (700 × 600 × 5 μm) integrated by an array of silicon beams and p-type piezoresistive sensing elements, which need an easy fabrication process. The proposed microsensor has a resolution of 80 nT, a sensitivity of 1.2 V.T(-1), a resonant frequency of 13.87 kHz, low power consumption (2.05 mW), quality factor of 93 at atmospheric pressure, and requires a simple signal processing circuit. The importance of our study is twofold. First, because the artificial neuron can generate well-controlled magnetic flux density, we suggest it could be used to analyze the resolution and performance of different magnetic field sensors intended for neurobiological applications. Second, the introduced MEMS magnetic field sensor may be used as a prototype to develop new high-resolution biomedical microdevices to sense magnetic fields from cardiac tissue, nerves, spinal cord, or the brain.

Magnetic field sensor for isotropically sensing an incident magnetic field in a sensor plane

NASA Technical Reports Server (NTRS)

Pant, Bharat B. (Inventor); Wan, Hong (Inventor)

2001-01-01

A magnetic field sensor that isotropically senses an incident magnetic field. This is preferably accomplished by providing a magnetic field sensor device that has one or more circular shaped magnetoresistive sensor elements for sensing the incident magnetic field. The magnetoresistive material used is preferably isotropic, and may be a CMR material or some form of a GMR material. Because the sensor elements are circular in shape, shape anisotropy is eliminated. Thus, the resulting magnetic field sensor device provides an output that is relatively independent of the direction of the incident magnetic field in the sensor plane.

[Symbolism on "natural" in food].

PubMed

da Veiga Soares Carvalho, Maria Claudia; Luz, Madel Therezinha

2011-01-01

The incorporated senses represent a set of possibilities for future life able to build individual and collective identities. This work deepens the habitus, in Bourdieu's terms, associated with "natural" and fast-food styles, making an interpretative analysis of symbolic exchanges of elements reproduced in feeding practices. We believe that this bricolage arrangement of elements enables bartering and hybridism, marked by a tension that reflects the insecurity of technological innovations. The "natural" style represents an ideal of self-sustainability, non-polluting production, which faces the sanitary and ecologic crisis of the planet, against the large-scale industrialization and fast urbanization, defined as depredation factors of basic living conditions. The exchanges happen in a symbolic game connected with the global economic game, in which social actors make bets, illusio, according to particular intentions in concrete action. There is a chance to reformulate the rules of the game in the "game", although with a precarious balance of forces, in which the weaker side loses, an agent may have the possibility of not reproducing the pressures of globalized feeding, which is far from what might seem supernatural.

Ergonomically neutral arm support system

DOEpatents

Siminovitch, Michael J; Chung, Jeffrey Y; Dellinges, Steven; Lafever, Robin E

2005-08-02

An ergonomic arm support system maintains a neutral position for the forearm. A mechanical support structure attached to a chair or other mounting structure supports the arms of a sitting or standing person. The system includes moving elements and tensioning elements to provide a dynamic balancing force against the forearms. The support structure is not fixed or locked in a rigid position, but is an active dynamic system that is maintained in equipoise by the continuous operation of the opposing forces. The support structure includes an armrest connected to a flexible linkage or articulated or pivoting assembly, which includes a tensioning element such as a spring. The pivoting assembly moves up and down, with the tensioning element providing the upward force that balances the downward force of the arm.

A Force-Visualized Silicone Retractor Attachable to Surgical Suction Pipes.

PubMed

Watanabe, Tetsuyou; Koyama, Toshio; Yoneyama, Takeshi; Nakada, Mitsutoshi

2017-04-05

This paper presents a force-visually-observable silicone retractor, which is an extension of a previously developed system that had the same functions of retracting, suction, and force sensing. These features provide not only high usability by reducing the number of tool changes, but also a safe choice of retracting by visualized force information. Suction is achieved by attaching the retractor to a suction pipe. The retractor has a deformable sensing component including a hole filled with a liquid. The hole is connected to an outer tube, and the liquid level displaced in proportion to the extent of deformation resulting from the retracting load. The liquid level is capable to be observed around the surgeon's fingertips, which enhances the usability. The new hybrid structure of soft sensing and hard retracting allows the miniaturization of the retractor as well as a resolution of less than 0.05 N and a range of 0.1-0.7 N. The overall structure is made of silicone, which has the advantages of disposability, low cost, and easy sterilization/disinfection. This system was validated by conducting experiments.

Discerning the role of mechanosensors in regulating proximal tubule function

PubMed Central

Weisz, Ora A.

2015-01-01

All cells in the body experience external mechanical forces such as shear stress and stretch. These forces are sensed by specialized structures in the cell known as mechanosensors. Cells lining the proximal tubule (PT) of the kidney are continuously exposed to variations in flow rates of the glomerular ultrafiltrate, which manifest as changes in axial shear stress and radial stretch. Studies suggest that these cells respond acutely to variations in flow by modulating their ion transport and endocytic functions to maintain glomerulotubular balance. Conceptually, changes in the axial shear stress in the PT could be sensed by three known structures, namely, the microvilli, the glycocalyx, and primary cilia. The orthogonal component of the force produced by flow exhibits as radial stretch and can cause expansion of the tubule. Forces of stretch are transduced by integrins, by stretch-activated channels, and by cell-cell contacts. This review summarizes our current understanding of flow sensing in PT epithelia, discusses challenges in dissecting the role of individual flow sensors in the mechanosensitive responses, and identifies potential areas of opportunity for new study. PMID:26662200

Polymer-based materials to be used as the active element in microsensors: a scanning force microscopy study

PubMed

Porter; Eastman; Pace; Bradley

2000-09-01

Polymer-based materials can be incorporated as the active sensing elements in chemiresistor devices. Most of these devices take advantage of the fact that certain polymers will swell when exposed to gaseous analytes. To measure this response, a conducting material such as carbon black is incorporated within the nonconducting polymer matrix. In response to analytes, polymer swelling results in a measurable change in the conductivity of the polymer/carbon composite material. Arrays of these sensors may be used in conjunction with pattern recognition techniques for purposes of analyte recognition and quantification. We have used the technique of scanning force microscopy (SFM) to investigate microstructural changes in carbon-polymer composites formed from the polymers poly (isobutylene) (PIB), poly (vinyl alcohol) (PVA), and poly (ethylene-vinyl acetate) (PEVA) when exposed to the analytes hexane, toluene, water, ethanol, and acetone. Using phase-contrast imaging (PI), changes in the carbon nanoparticle distribution on the surface of the polymer matrix are measured as the polymers are exposed to the analytes in vapor phase. In some but not all cases, the changes were reversible (at the scale of the SFM measurements) upon removal of the analyte vapor. In this paper, we also describe a new type of microsensor based on piezoresistive microcantilever technology. With these new devices, polymeric volume changes accompanying exposure to analyte vapor are measured directly by a piezoresistive microcantilever in direct contact with the polymer. These devices may offer a number of advantages over standard chemiresistor-based sensors.

Ice Particle Impact on Cloud Water Content Instrumentation

NASA Technical Reports Server (NTRS)

Emery, Edward F.; Miller, Dean R.; Plaskon, Stephen R.; Strapp, Walter; Lillie, Lyle

2004-01-01

Determining the total amount of water contained in an icing cloud necessitates the measurement of both the liquid droplets and ice particles. One commonly accepted method for measuring cloud water content utilizes a hot wire sensing element, which is maintained at a constant temperature. In this approach, the cloud water content is equated with the power required to keep the sense element at a constant temperature. This method inherently assumes that impinging cloud particles remain on the sensing element surface long enough to be evaporated. In the case of ice particles, this assumption requires that the particles do not bounce off the surface after impact. Recent tests aimed at characterizing ice particle impact on a thermally heated wing section, have raised questions about the validity of this assumption. Ice particles were observed to bounce off the heated wing section a very high percentage of the time. This result could have implications for Total Water Content sensors which are designed to capture ice particles, and thus do not account for bouncing or breakup of ice particles. Based on these results, a test was conducted to investigate ice particle impact on the sensing elements of the following hot-wire cloud water content probes: (1) Nevzorov Total Water Content (TWC)/Liquid Water Content (LWC) probe, (2) Science Engineering Associates TWC probe, and (3) Particle Measuring Systems King probe. Close-up video imaging was used to study ice particle impact on the sensing element of each probe. The measured water content from each probe was also determined for each cloud condition. This paper will present results from this investigation and attempt to evaluate the significance of ice particle impact on hot-wire cloud water content measurements.

Recent developments in OLED-based chemical and biological sensors

NASA Astrophysics Data System (ADS)

Shinar, Joseph; Zhou, Zhaoqun; Cai, Yuankun; Shinar, Ruth

2007-09-01

Recent developments in the structurally integrated OLED-based platform of luminescent chemical and biological sensors are reviewed. In this platform, an array of OLED pixels, which is structurally integrated with the sensing elements, is used as the photoluminescence (PL) excitation source. The structural integration is achieved by fabricating the OLED array and the sensing element on opposite sides of a common glass substrate or on two glass substrates that are attached back-to-back. As it does not require optical fibers, lens, or mirrors, it results in a uniquely simple, low-cost, and potentially rugged geometry. The recent developments on this platform include the following: (1) Enhancing the performance of gas-phase and dissolved oxygen sensors. This is achieved by (a) incorporating high-dielectric TiO II nanoparticles in the oxygen-sensitive Pt and Pd octaethylporphyrin (PtOEP and PdOEP, respectively)- doped polystyrene (PS) sensor films, and (b) embedding the oxygen-sensitive dyes in a matrix of polymer blends such as PS:polydimethylsiloxane (PDMS). (2) Developing sensor arrays for simultaneous detection of multiple serum analytes, including oxygen, glucose, lactate, and alcohol. The sensing element for each analyte consists of a PtOEP-doped PS oxygen sensor, and a solution containing the oxidase enzyme specific to the analyte. Each sensing element is coupled to two individually addressable OLED pixels and a Si photodiode photodetector (PD). (3) Enhancing the integration of the platform, whereby a PD array is also structurally integrated with the OLED array and sensing elements. This enhanced integration is achieved by fabricating an array of amorphous or nanocrystalline Si-based PDs, followed by fabrication of the OLED pixels in the gaps between these Si PDs.

The Use of Remote Sensing Satellites for Verification in International Law

NASA Astrophysics Data System (ADS)

Hettling, J. K.

The contribution is a very sensitive topic which is currently about to gain significance and importance in the international community. It implies questions of international law as well as the contemplation of new developments and decisions in international politics. The paper will begin with the meaning and current status of verification in international law as well as the legal basis of satellite remote sensing in international treaties and resolutions. For the verification part, this implies giving a definition of verification and naming its fields of application and the different means of verification. For the remote sensing part, it involves the identification of relevant provisions in the Outer Space Treaty and the United Nations General Assembly Principles on Remote Sensing. Furthermore it shall be looked at practical examples: in how far have remote sensing satellites been used to verify international obligations? Are there treaties which would considerably profit from the use of remote sensing satellites? In this respect, there are various examples which can be contemplated, such as the ABM Treaty (even though out of force now), the SALT and START Agreements, the Chemical Weapons Convention and the Conventional Test Ban Treaty. It will be mentioned also that NGOs have started to verify international conventions, e.g. Landmine Monitor is verifying the Mine-Ban Convention. Apart from verifying arms control and disarmament treaties, satellites can also strengthen the negotiation of peace agreements (such as the Dayton Peace Talks) and the prevention of international conflicts from arising. Verification has played an increasingly prominent role in high-profile UN operations. Verification and monitoring can be applied to the whole range of elements that constitute a peace implementation process, ranging from the military aspects through electoral monitoring and human rights monitoring, from negotiating an accord to finally monitoring it. Last but not least the problem of enforcing international obligations needs to be addressed, especially the dependence of international law on the will of political leaders and their respective national interests.

Enhanced damping for bridge cables using a self-sensing MR damper

NASA Astrophysics Data System (ADS)

Chen, Z. H.; Lam, K. H.; Ni, Y. Q.

2016-08-01

This paper investigates enhanced damping for protecting bridge stay cables from excessive vibration using a newly developed self-sensing magnetorheological (MR) damper. The semi-active control strategy for effectively operating the self-sensing MR damper is formulated based on the linear-quadratic-Gaussian (LQG) control by further considering a collocated control configuration, limited measurements and nonlinear damper dynamics. Due to its attractive feature of sensing-while-damping, the self-sensing MR damper facilitates the collocated control. On the other hand, only the sensor measurements from the self-sensing device are employed in the feedback control. The nonlinear dynamics of the self-sensing MR damper, represented by a validated Bayesian NARX network technique, are further accommodated in the control formulation to compensate for its nonlinearities. Numerical and experimental investigations are conducted on stay cables equipped with the self-sensing MR damper operated in passive and semi-active control modes. The results verify that the collocated self-sensing MR damper facilitates smart damping for inclined cables employing energy-dissipative LQG control with only force and displacement measurements at the damper. It is also demonstrated that the synthesis of nonlinear damper dynamics in the LQG control enhances damping force tracking efficiently, explores the features of the self-sensing MR damper, and achieves better control performance over the passive MR damping control and the Heaviside step function-based LQG control that ignores the damper dynamics.

Sensors Technology and Advanced Signal Processing Concepts for Layered Warfare/Layered Sensing

DTIC Science & Technology

2010-04-01

for challenged environments will require contributions from many diverse technical disciplines across AFRL, the Air Force and beyond. By providing a...APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. STINFO COPY AIR FORCE...UNITED STATES AIR FORCE AIR FORCE MATERIEL COMMAND NOTICE AND SIGNATURE PAGE Using Government drawings, specifications, or other data

Semiconducter Optical Amplifier as a Phase Modulator for Coherent Laser Radar (Preprint)

DTIC Science & Technology

2012-01-01

AIR FORCE RESEARCH LABORATORY SENSORS DIRECTORATE WRIGHT-PATTERSON AIR FORCE BASE, OH 45433-7320 AIR FORCE MATERIEL COMMAND UNITED STATES... AIR FORCE NOTICE AND SIGNATURE PAGE Using Government drawings, specifications, or other data included in this document for any purpose other...NUMBER Multispectral Sensing and Detection Division LADAR Technology Branch (AFRL/RYMM) Air Force Research Laboratory, Sensors Directorate Wright

Satellite Remote Sensing of Aerosol Forcing

NASA Technical Reports Server (NTRS)

Remer, Lorraine; Kaufman, Yoram; Ramaprasad, Jaya; Procopio, Aline; Levin, Zev

1999-01-01

The role of aerosol forcing remains one of the largest uncertainties in estimating man's impact on the global climate system. One school of thought suggests that remote sensing by satellite sensors will provide the data necessary to narrow these uncertainties. While satellite measurements of direct aerosol forcing appear to be straightforward, satellite measurements of aerosol indirect forcing will be more complicated. Pioneering studies identified indirect aerosol forcing using AVHRR data in the biomass burning regions of Brazil. We have expanded this analysis with AVHRR to include an additional year of data and assimilated water vapor fields. The results show similar latitudinal dependence as reported by Kaufman and Fraser, but by using water vapor observations we conclude that latitude is not a proxy for water vapor and the strength of the indirect effect is not correlated to water vapor amounts. In addition to the AVHRR study we have identified indirect aerosol forcing in Brazil at much smaller spatial scales using the MODIS Airborne Simulator. The strength of the indirect effect appears to be related to cloud type and cloud dynamics. There is a suggestion that some of the cloud dynamics may be influenced by smoke destabilization of the atmospheric column. Finally, this study attempts to quantify remote sensing limitations due to the accuracy limits of the retrieval algorithms. We use a combination of numerical aerosol transport models, ground-based AERONET data and ISCCP cloud climatology to determine how much of the forcing occurs in regions too clean to determine from satellite retrievals.

Fully printed flexible fingerprint-like three-axis tactile and slip force and temperature sensors for artificial skin.

PubMed

Harada, Shingo; Kanao, Kenichiro; Yamamoto, Yuki; Arie, Takayuki; Akita, Seiji; Takei, Kuniharu

2014-12-23

A three-axis tactile force sensor that determines the touch and slip/friction force may advance artificial skin and robotic applications by fully imitating human skin. The ability to detect slip/friction and tactile forces simultaneously allows unknown objects to be held in robotic applications. However, the functionalities of flexible devices have been limited to a tactile force in one direction due to difficulties fabricating devices on flexible substrates. Here we demonstrate a fully printed fingerprint-like three-axis tactile force and temperature sensor for artificial skin applications. To achieve economic macroscale devices, these sensors are fabricated and integrated using only printing methods. Strain engineering enables the strain distribution to be detected upon applying a slip/friction force. By reading the strain difference at four integrated force sensors for a pixel, both the tactile and slip/friction forces can be analyzed simultaneously. As a proof of concept, the high sensitivity and selectivity for both force and temperature are demonstrated using a 3×3 array artificial skin that senses tactile, slip/friction, and temperature. Multifunctional sensing components for a flexible device are important advances for both practical applications and basic research in flexible electronics.

Modeling and design optimization of adhesion between surfaces at the microscale.

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

Sylves, Kevin T.

2008-08-01

This research applies design optimization techniques to structures in adhesive contact where the dominant adhesive mechanism is the van der Waals force. Interface finite elements are developed for domains discretized by beam elements, quadrilateral elements or triangular shell elements. Example analysis problems comparing finite element results to analytical solutions are presented. These examples are then optimized, where the objective is matching a force-displacement relationship and the optimization variables are the interface element energy of adhesion or the width of beam elements in the structure. Several parameter studies are conducted and discussed.

Method for in-situ restoration of plantinum resistance thermometer calibration

DOEpatents

Carroll, Radford M.

1989-01-01

A method is provided for in-situ restoration of platinum resistance thermometers (PRT's) that have undergone surface oxide contamination and/or strain-related damage causing decalibration. The method, which may be automated using a programmed computer control arrangement, consists of applying a dc heating current to the resistive sensing element of the PRT of sufficient magnitude to heat the element to an annealing temperature and maintaining the temperature for a specified period to restore the element to a stress-free calibration condition. The process anneals the sensing element of the PRT without subjecting the entire PRT assembly to the annealing temperature and may be used in the periodic maintenance of installed PRT's.

Method for in-situ restoration of platinum resistance thermometer calibration

DOEpatents

Carroll, R.M.

1987-10-23

A method is provided for in-situ restoration of platinum resistance thermometers (PRT's) that have undergone surface oxide contamination and/or stain-related damage causing decalibration. The method, which may be automated using a programmed computer control arrangement, consists of applying a dc heating current to the resistive sensing element of the PRT of sufficient magnitude to heat the element to an annealing temperature and maintaining the temperature for a specified period to restore the element to a stress-free calibration condition. The process anneals the sensing element of the PRT without subjecting the entire PRT assembly to the annealing temperature and may be used in the periodic maintenance of installed PRT's. 1 fig.

Optical Sensors for Biomolecules Using Nanoporous Sol-Gel Materials

NASA Technical Reports Server (NTRS)

Fang, Jonathan; Zhou, Jing C.; Lan, Esther H.; Dunn, Bruce; Gillman, Patricia L.; Smith, Scott M.

2004-01-01

An important consideration for space missions to Mars is the ability to detect biosignatures. Solid-state sensing elements for optical detection of biological entities are possible using sol-gel based biologically active materials. We have used these materials as optical sensing elements in a variety of bioassays, including immunoassays and enzyme assays. By immobilizing an appropriate biomolecule in the sol-gel sensing element, we have successfully detected analytes such as amino acids and hormones. In the case of the amino acid glutamate, the enzyme glutamate dehydrogenase was the immobilized molecule, whereas in the case of the hormone cortisol, an anti-cortisol antibody was immobilized in the sensing element. In this previous work with immobilized enzymes and antibodies, excellent sensitivity and specificity were demonstrated in a variety of formats including bulk materials, thin films and fibers. We believe that the sol-gel approach is an attractive platform for bioastronautics sensing applications because of the ability to detect a wide range of entities such as amino acids, fatty acids, hopanes, porphyrins, etc. The sol-gel approach produces an optically transparent 3D silica matrix that forms around the biomolecule of interest, thus stabilizing its structure and functionality while allowing for optical detection. This encapsulation process protects the biomolecule and leads to a more "rugged" sensor. The nanoporous structure of the sol-gel matrix allows diffusion of small target molecules but keeps larger, biomolecules immobilized in the pores. We are currently developing these biologically active sol-gel materials into small portable devices for on-orbit cortisol detection

Functional relationship between skull form and feeding mechanics in Sphenodon, and implications for diapsid skull development.

PubMed

Curtis, Neil; Jones, Marc E H; Shi, Junfen; O'Higgins, Paul; Evans, Susan E; Fagan, Michael J

2011-01-01

The vertebrate skull evolved to protect the brain and sense organs, but with the appearance of jaws and associated forces there was a remarkable structural diversification. This suggests that the evolution of skull form may be linked to these forces, but an important area of debate is whether bone in the skull is minimised with respect to these forces, or whether skulls are mechanically "over-designed" and constrained by phylogeny and development. Mechanical analysis of diapsid reptile skulls could shed light on this longstanding debate. Compared to those of mammals, the skulls of many extant and extinct diapsids comprise an open framework of fenestrae (window-like openings) separated by bony struts (e.g., lizards, tuatara, dinosaurs and crocodiles), a cranial form thought to be strongly linked to feeding forces. We investigated this link by utilising the powerful engineering approach of multibody dynamics analysis to predict the physiological forces acting on the skull of the diapsid reptile Sphenodon. We then ran a series of structural finite element analyses to assess the correlation between bone strain and skull form. With comprehensive loading we found that the distribution of peak von Mises strains was particularly uniform throughout the skull, although specific regions were dominated by tensile strains while others were dominated by compressive strains. Our analyses suggest that the frame-like skulls of diapsid reptiles are probably optimally formed (mechanically ideal: sufficient strength with the minimal amount of bone) with respect to functional forces; they are efficient in terms of having minimal bone volume, minimal weight, and also minimal energy demands in maintenance. © 2011 Curtis et al.

Naval EarthMap Observer (NEMO) Hyperspectral Remote Sensing Program

DTIC Science & Technology

2000-10-01

The NEMO hyperspectral remote sensing program will provide unclassified, space-based hyperspectral passive imagery at moderate resolution that offers substantial potential for direct use by Naval forces and the Civil Sector.

High Angular Resolution Microwave Sensing with Large, Sparse, Random Arrays

DTIC Science & Technology

1983-11-01

RESEARCH AFOSR 82-0012 DTIC s" A6 19M UNIVERSITY of PENNSYLVANIA VALLEY FORGE RESEARCH CENTER THE MOORE SCHOOL OF ELECTRICAL ENGINEERING PHILADELPHIA...MICROWAVE SENSING WITH LARGE, SPARSE, RANDOM ARRAYS Final Scientific Report AIR FORCE OFFICE OF SCIENTIFIC RESEARCH AFOSR 82-0012 Valley Forge Research ...CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE Air Force Office of Scientific Research /NE Nov 1983 - . Bildin 41073. NUMBER Or PAG ES BOllinZ AFB, DIC

Special Operations Forces to the Twenty-First Century: What Threat, What Response

DTIC Science & Technology

1991-05-24

successful campaign plan against the German war machine had been the use of resistance forces, the Maquis in France, the Partisans in Yugoslavia, and...General Eisenhower reckoned the Maquis resistance had been worth 15 divisions./4 Some far-seeing planners realized that should the Soviets roll...Prime minister and others, less noted by western eyes . India has a sense of history and a sense of paranoia. She knows that in Africa from Kuwait to

Public Universities and the Neoliberal Common Sense: Seven Iconoclastic Theses

ERIC Educational Resources Information Center

Torres, Carlos Alberto

2011-01-01

Neoliberalism has utterly failed as a viable model of economic development, yet the politics of culture associated with neoliberalism is still in force, becoming the new common sense shaping the role of government and education. This "common sense" has become an ideology playing a major role in constructing hegemony as moral and intellectual…

Empowering Volunteer Money Sense Advisors at a Military Installation.

ERIC Educational Resources Information Center

Wright, Joan; Varcoe, Karen

Because money management is often a problem for lower-level military personnel, a resource management educational program called Money Sense was started by the University of California Cooperative Extension at Edwards Air Force Base in 1985. Volunteers for Money Sense were recruited at the base; they attended eight sessions on teaching techniques…

32 CFR 842.22 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE CLAIMS AND LITIGATION ADMINISTRATIVE... military purpose and used or controlled by the Air Force or any other Department of Defense (DOD) element... area or any real estate the Air Force or any other DOD element uses or controls. (d) Personal property...

Adult Services in the Third Millennium.

ERIC Educational Resources Information Center

Monroe, Margaret E.

1979-01-01

Presents a four-step model for "planning" or "forecasting" future of adult services in public libraries: (1) identification of forces at work; (2) analysis of probable impacts of one force upon another; (3) identification of preferred (and rejected) elements of future with forces that control elements; and (4) strategies to be…

A self-sensing magnetorheological damper with power generation

NASA Astrophysics Data System (ADS)

Chen, Chao; Liao, Wei-Hsin

2012-02-01

Magnetorheological (MR) dampers are promising for semi-active vibration control of various dynamic systems. In the current MR damper systems, a separate power supply and dynamic sensor are required. To enable the MR damper to be self-powered and self-sensing in the future, in this paper we propose and investigate a self-sensing MR damper with power generation, which integrates energy harvesting, dynamic sensing and MR damping technologies into one device. This MR damper has self-contained power generation and velocity sensing capabilities, and is applicable to various dynamic systems. It combines the advantages of energy harvesting—reusing wasted energy, MR damping—controllable damping force, and sensing—providing dynamic information for controlling system dynamics. This multifunctional integration would bring great benefits such as energy saving, size and weight reduction, lower cost, high reliability, and less maintenance for the MR damper systems. In this paper, a prototype of the self-sensing MR damper with power generation was designed, fabricated, and tested. Theoretical analyses and experimental studies on power generation were performed. A velocity-sensing method was proposed and experimentally validated. The magnetic-field interference among three functions was prevented by a combined magnetic-field isolation method. Modeling, analysis, and experimental results on damping forces are also presented.

Design considerations of manipulator and feel system characteristics in roll tracking

NASA Technical Reports Server (NTRS)

Johnston, Donald E.; Aponso, Bimal L.

1988-01-01

A fixed-base simulation was performed to identify and quantify interactions between the pilot's hand/arm neuromuscular subsystem and such control system features of typical modern fighter aircraft roll rate command mechanizations as: (1) force versus displacement sensing side-stick type manipulator, (2) feel force/displacement gradient, (3) feel system versus command prefilter dynamic lag, and (4) flight control system effective time delay. The experiment encompassed some 48 manipulator/filter/aircraft configurations. Displacement side-stick experiment results are given and compared with the previous force sidestick experiment results. Attention is focused on control bandwidth, excitement (peaking) of the neuromuscular mode, feel force/displacement gradient effects, time delay effects, etc. Section 5 is devoted to experiments with a center-stick in which force versus displacement sensing, feel system lag, and command prefilter lag influences on tracking performance and pilot preference are investigated.

Lipid nanotube or nanowire sensor

DOEpatents

Noy, Aleksandr [Belmont, CA; Bakajin, Olgica [San Leandro, CA; Letant, Sonia [Livermore, CA; Stadermann, Michael [Dublin, CA; Artyukhin, Alexander B [Menlo Park, CA

2009-06-09

A sensor apparatus comprising a nanotube or nanowire, a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer. Also a biosensor apparatus comprising a gate electrode; a source electrode; a drain electrode; a nanotube or nanowire operatively connected to the gate electrode, the source electrode, and the drain electrode; a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer.

Lipid nanotube or nanowire sensor

DOEpatents

Noy, Aleksandr [Belmont, CA; Bakajin, Olgica [San Leandro, CA; Letant, Sonia [Livermore, CA; Stadermann, Michael [Dublin, CA; Artyukhin, Alexander B [Menlo Park, CA

2010-06-29

A sensor apparatus comprising a nanotube or nanowire, a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer. Also a biosensor apparatus comprising a gate electrode; a source electrode; a drain electrode; a nanotube or nanowire operatively connected to the gate electrode, the source electrode, and the drain electrode; a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer.

Quality use of the computer: Computational mechanics, artificial intelligence, robotics, and acoustic sensing; Proceedings of the ASME/JSME Pressure Vessels and Piping Conference, Honolulu, HI, July 23-27, 1989

NASA Astrophysics Data System (ADS)

Cory, J. F., Jr.; Gordon, J. L.; Miyoshi, T.; Suzuki, K.

1989-06-01

Papers are presented on the use of microcomputers, supercomputers, and workstations in solid and structural mechanics. Artificial intelligence technology, the development and use of expert systems, and research in the area of robotics are discussed. Attention is also given to probabilistic finite element and boundary element methods and acoustic sensing.

Torus elements used in effective shock absorber

NASA Technical Reports Server (NTRS)

Cunningham, P.; Platus, D. L.

1966-01-01

Energy absorbing device forces torus elements to revolve annularly between two concentric tubes when a load is applied to one tube. Interference forces can be varied by using torus elements of different thicknesses. The device operates repeatedly in compression or tension, and under problems of large onset rate tolerance or structural overload.

Smart wearable Kevlar-based safeguarding electronic textile with excellent sensing performance.

PubMed

Wang, Sheng; Xuan, Shouhu; Liu, Mei; Bai, Linfeng; Zhang, Shuaishuai; Sang, Min; Jiang, Wanquan; Gong, Xinglong

2017-03-29

A novel S-ST/MWCNT/Kevlar-based wearable electronic textile (WET) with enhanced safeguarding performance and force sensing ability was fabricated. Stab resistance performance tests under quasi-static and dynamic conditions show that the maximum resistance force and penetration impact energy for the WET are 18 N and 11.76 J, which represent a 90% and 50% increment with respect to the neat Kevlar, respectively. Dynamic impact resistance tests show that the WET absorbs all the impact energy. The maximum resistance force of the WET is 1052 N, which represents an improvement of about 190% with respect to neat Kevlar. With the incorporation of multi-walled carbon nanotubes (MWCNTs), the WET can achieve a stable electrical conductivity of ∼10 -2 S m -1 , and the conductivity is highly sensitive to external mechanic forces. Notably, the sensing fabric also exhibits an outstanding ability to detect and analyze external forces. In addition, it can be fixed at any position of the human body and exhibits an ideal monitoring performance. Because of its flexibility, high sensitivity to various types of deformations and excellent safeguarding performance, the WET has a strong potential for wearable monitoring devices that simultaneously provide body protection and monitor the movements of the human body under various conditions.

Compression force sensing regulates integrin αIIbβ3 adhesive function on diabetic platelets.

PubMed

Ju, Lining; McFadyen, James D; Al-Daher, Saheb; Alwis, Imala; Chen, Yunfeng; Tønnesen, Lotte L; Maiocchi, Sophie; Coulter, Brianna; Calkin, Anna C; Felner, Eric I; Cohen, Neale; Yuan, Yuping; Schoenwaelder, Simone M; Cooper, Mark E; Zhu, Cheng; Jackson, Shaun P

2018-03-14

Diabetes is associated with an exaggerated platelet thrombotic response at sites of vascular injury. Biomechanical forces regulate platelet activation, although the impact of diabetes on this process remains ill-defined. Using a biomembrane force probe (BFP), we demonstrate that compressive force activates integrin α IIb β 3 on discoid diabetic platelets, increasing its association rate with immobilized fibrinogen. This compressive force-induced integrin activation is calcium and PI 3-kinase dependent, resulting in enhanced integrin affinity maturation and exaggerated shear-dependent platelet adhesion. Analysis of discoid platelet aggregation in the mesenteric circulation of mice confirmed that diabetes leads to a marked enhancement in the formation and stability of discoid platelet aggregates, via a mechanism that is not inhibited by therapeutic doses of aspirin and clopidogrel, but is eliminated by PI 3-kinase inhibition. These studies demonstrate the existence of a compression force sensing mechanism linked to α IIb β 3 adhesive function that leads to a distinct prothrombotic phenotype in diabetes.

High bandwidth piezoresistive force probes with integrated thermal actuation

PubMed Central

Doll, Joseph C.; Pruitt, Beth L.

2012-01-01

We present high-speed force probes with on-chip actuation and sensing for the measurement of pN-scale forces at the microsecond time scale. We achieve a high resonant frequency in water (1–100 kHz) with requisite low spring constants (0.3–40 pN/nm) and low integrated force noise (1–100 pN) by targeting probe dimensions on the order of 300 nm thick, 1–2 μm wide and 30–200 μm long. Forces are measured using silicon piezoresistors while the probes are actuated thermally with an aluminum unimorph and silicon heater. The piezoresistive sensors are designed using open source numerical optimization code that incorporates constraints on operating temperature. Parylene passivation enables operation in ionic media and we demonstrate simultaneous actuation and sensing. The improved design and fabrication techniques that we describe enable a 10–20 fold improvement in force resolution or measurement bandwidth over prior piezoresistive cantilevers of comparable thickness. PMID:23175616

Effects of radiation upon the light-sensing elements of the retina as characterized by scanning electron microscopy

NASA Technical Reports Server (NTRS)

Malachowski, M. J.; Tobias, C. A.; Leith, J. T.

1977-01-01

A model system using Necturus maculosus, the common mudpuppy, was established for evaluating effects of radiation upon the light-sensing elements of the retina. Accelerated heavy ions of helium and neon from the Berkeley Bevalac were used. A number of criteria were chosen to characterize radiation damage by observing morphological changes with the scanning electron microscope. The studies indicated retina sensitivity to high-LET (neon) particles at radiation levels below 10 rads (7 particles per visual element) whereas no significant effects were seen from fast helium ions below 50 rads.

Injury Risk Assessment of Non-Lethal Projectile Head Impacts

PubMed Central

Oukara, Amar; Nsiampa, Nestor; Robbe, Cyril; Papy, Alexandre

2014-01-01

Kinetic energy non-lethal projectiles are used to impart sufficient effect onto a person in order to deter uncivil or hazardous behavior with a low probability of permanent injury. Since their first use, real cases indicate that the injuries inflicted by such projectiles may be irreversible and sometimes lead to death, especially for the head impacts. Given the high velocities and the low masses involved in such impacts, the assessment approaches proposed in automotive crash tests and sports may not be appropriate. Therefore, there is a need of a specific approach to assess the lethality of these projectiles. In this framework, some recent research data referred in this article as “force wall approach” suggest the use of three lesional thresholds (unconsciousness, meningeal damages and bone damages) that depend on the intracranial pressure. Three corresponding critical impact forces are determined for a reference projectile. Based on the principle that equal rigid wall maximal impact forces will produce equal damage on the head, these limits can be determined for any other projectile. In order to validate the consistence of this innovative method, it is necessary to compare the results with other existing assessment methods. This paper proposes a comparison between the “force wall approach” and two different head models. The first one is a numerical model (Strasbourg University Finite Element Head Model-SUFEHM) from Strasbourg University; the second one is a mechanical surrogate (Ballistics Load Sensing Headform-BLSH) from Biokinetics. PMID:25400712

Ionic signaling in plant responses to gravity and touch

NASA Technical Reports Server (NTRS)

Fasano, Jeremiah M.; Massa, Gioia D.; Gilroy, Simon

2002-01-01

Touch and gravity are two of the many stimuli that plants must integrate to generate an appropriate growth response. Due to the mechanical nature of both of these signals, shared signal transduction elements could well form the basis of the cross-talk between these two sensory systems. However, touch stimulation must elicit signaling events across the plasma membrane whereas gravity sensing is thought to represent transformation of an internal force, amyloplast sedimentation, to signal transduction events. In addition, factors such as turgor pressure and presence of the cell wall may also place unique constraints on these plant mechanosensory systems. Even so, the candidate signal transduction elements in both plant touch and gravity sensing, changes in Ca2+, pH and membrane potential, do mirror the known ionic basis of signaling in animal mechanosensory cells. Distinct spatial and temporal signatures of Ca2+ ions may encode information about the different mechanosignaling stimuli. Signals such as Ca2+ waves or action potentials may also rapidly transfer information perceived in one cell throughout a tissue or organ leading to the systemic reactions characteristic of plant touch and gravity responses. Longer-term growth responses are likely sustained via changes in gene expression and asymmetries in compounds such as inositol-1,4,5-triphosphate (IP3) and calmodulin. Thus, it seems likely that plant mechanoperception involves both spatial and temporal encoding of information at all levels, from the cell to the whole plant. Defining this patterning will be a critical step towards understanding how plants integrate information from multiple mechanical stimuli to an appropriate growth response.

Resolution of Forces and Strain Measurements from an Acoustic Ground Test

NASA Technical Reports Server (NTRS)

Smith, Andrew M.; LaVerde, Bruce T.; Hunt, Ronald; Waldon, James M.

2013-01-01

The Conservatism in Typical Vibration Tests was Demonstrated: Vibration test at component level produced conservative force reactions by approximately a factor of 4 (approx.12 dB) as compared to the integrated acoustic test in 2 out of 3 axes. Reaction Forces Estimated at the Base of Equipment Using a Finite Element Based Method were Validated: FEM based estimate of interface forces may be adequate to guide development of vibration test criteria with less conservatism. Element Forces Estimated in Secondary Structure Struts were Validated: Finite element approach provided best estimate of axial strut forces in frequency range below 200 Hz where a rigid lumped mass assumption for the entire electronics box was valid. Models with enough fidelity to represent diminishing apparent mass of equipment are better suited for estimating force reactions across the frequency range. Forward Work: Demonstrate the reduction in conservatism provided by; Current force limited approach and an FEM guided approach. Validate proposed CMS approach to estimate coupled response from uncoupled system characteristics for vibroacoustics.

Semiconductor acceleration sensor

NASA Astrophysics Data System (ADS)

Ueyanagi, Katsumichi; Kobayashi, Mitsuo; Goto, Tomoaki

1996-09-01

This paper reports a practical semiconductor acceleration sensor especially suited for automotive air bag systems. The acceleration sensor includes four beams arranged in a swastika structure. Two piezoresistors are formed on each beam. These eight piezoresistors constitute a Wheatstone bridge. The swastika structure of the sensing elements, an upper glass plate and a lower glass plate exhibit the squeeze film effect which enhances air dumping, by which the constituent silicon is prevented from breakdown. The present acceleration sensor has the following features. The acceleration force component perpendicular to the sensing direction can be cancelled. The cross-axis sensitivity is less than 3 percent. And, the erroneous offset caused by the differences between the thermal expansion coefficients of the constituent materials can be canceled. The high aspect ratio configuration realized by plasma etching facilitates reducing the dimensions and improving the sensitivity of the acceleration sensor. The present acceleration sensor is 3.9 mm by 3.9 mm in area and 1.2 mm in thickness. The present acceleration sensor can measure from -50 to +50 G with sensitivity of 0.275 mV/G and with non-linearity of less than 1 percent. The acceleration sensor withstands shock of 3000 G.

Orbital Applications of Electrodynamic Propulsion

DTIC Science & Technology

1993-12-01

Constraint function 4 Greenwich equatorial frame Nt Amp2 .m2/kg 2 Minimize function W Amp2 r-m2 /kg 2 Constrained minimize function h Equinoctial element ...studies will be how a force, besides the two body force, changes the orbital elements . For this, we turn to the force form of Lagrange’s planetary...singularity in e of Equa- tion (10). To do this we introduce two of the equinoctial elements (18:22): h = esinw k = ecosw 11 Note we easily recover e

Application of laser ranging and VLBI data to a study of plate tectonic driving forces. [finite element method

NASA Technical Reports Server (NTRS)

Solomon, S. C.

1980-01-01

The measurability of changes in plate driving or resistive forces associated with plate boundary earthquakes by laser rangefinding or VLBI is considered with emphasis on those aspects of plate forces that can be characterized by such measurements. Topics covered include: (1) analytic solutions for two dimensional stress diffusion in a plate following earthquake faulting on a finite fault; (2) two dimensional finite-element solutions for the global state of stress at the Earth's surface for possible plate driving forces; and (3) finite-element solutions for three dimensional stress diffusion in a viscoelastic Earth following earthquake faulting.

Finite Element Modeling of Intermuscular Interactions and Myofascial Force Transmission

DTIC Science & Technology

2001-10-25

obtained explain force differences at the distal and proximal tendons of muscles that have mechanical interaction. This is in agreement with experimental...consequence is that active force generated within one muscle may be exerted at the tendon of another muscle. Keywords- Finite element method...7]. Therefore, in vivo there is an additional route for force transmission out off the muscle, which completely bypasses the tendon of the muscle

Nonlinear vibrations of thin arbitrarily laminated composite plates subjected to harmonic excitations using DKT elements

NASA Astrophysics Data System (ADS)

Chiang, C. K.; Xue, David Y.; Mei, Chuh

1993-04-01

A finite element formulation is presented for determining the large-amplitude free and steady-state forced vibration response of arbitrarily laminated anisotropic composite thin plates using the Discrete Kirchhoff Theory (DKT) triangular elements. The nonlinear stiffness and harmonic force matrices of an arbitrarily laminated composite triangular plate element are developed for nonlinear free and forced vibration analyses. The linearized updated-mode method with nonlinear time function approximation is employed for the solution of the system nonlinear eigenvalue equations. The amplitude-frequency relations for convergence with gridwork refinement, triangular plates, different boundary conditions, lamination angles, number of plies, and uniform versus concentrated loads are presented.

Nonlinear vibrations of thin arbitrarily laminated composite plates subjected to harmonic excitations using DKT elements

NASA Technical Reports Server (NTRS)

Chiang, C. K.; Xue, David Y.; Mei, Chuh

1993-01-01

A finite element formulation is presented for determining the large-amplitude free and steady-state forced vibration response of arbitrarily laminated anisotropic composite thin plates using the Discrete Kirchhoff Theory (DKT) triangular elements. The nonlinear stiffness and harmonic force matrices of an arbitrarily laminated composite triangular plate element are developed for nonlinear free and forced vibration analyses. The linearized updated-mode method with nonlinear time function approximation is employed for the solution of the system nonlinear eigenvalue equations. The amplitude-frequency relations for convergence with gridwork refinement, triangular plates, different boundary conditions, lamination angles, number of plies, and uniform versus concentrated loads are presented.

Device and method for redirecting electromagnetic signals

DOEpatents

Garcia, Ernest J.

1999-01-01

A device fabricated to redirect electromagnetic signals, the device including a primary driver adapted to provide a predetermined force, a linkage system coupled to the primary driver, a pusher rod rotationally coupled to the linkage system, a flexible rod element attached to the pusher rod and adapted to buckle upon the application of the predetermined force, and a mirror structure attached to the flexible rod element at one end and to the substrate at another end. When the predetermined force buckles the flexible rod element, the mirror structure and the flexible rod element both move to thereby allow a remotely-located electromagnetic signal directed towards the device to be redirected.

Development of a disposable force-sensing glove for clinicians and demonstration of its force measurements on patients during rehabilitation following anterior cruciate ligament reconstruction surgery

NASA Astrophysics Data System (ADS)

Wang, Wei-Chih; Linders, David R.; Nuckley, David J.

2017-12-01

For many clinicians, their effectiveness is dependent on the magnitude of forces they manually apply to their patients. However, current state-of-the-art care strategies lack quantitative feedback, making it difficult to provide consistent care over time and among multiple clinicians. To provide real-time quantitative feedback to clinicians, we have developed a disposable glove with a force sensor embedded in the fingertips or palm. The sensor is based on the fiber-optic bendloss effect whereby light intensity from an infrared source is attenuated as the fiber is bent between a series of corrugated teeth. The sensor fabricated has a very low profile (10×7×1 mm) and has demonstrated high sensitivity, accuracy, range, and durability. Force feedback up to 90 N with an average force threshold at 0.19 N and average sensor resolution at 0.05 N has been demonstrated. A preliminary clinical study has also been conducted with anterior cruciate ligament reconstruction patients who show significant range of motion improvement when treated with the force-sensing glove.

76 FR 50753 - Agency Information Collections Activities; The Pecora Award; Application and Nomination Process

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-16

... groups that make outstanding contributions toward understanding the earth by means of remote sensing. The... motivating force behind the establishment of a program for civil remote sensing of the earth from space. The purpose of the award is to recognize individuals or groups working in the field of remote sensing of the...

Basic Research at the University of Washington to Counter Improvised Explosive Devices

DTIC Science & Technology

2011-01-31

elements and fluorescent sensor elements can be co-located on the fiber. Having sensors with different sensing mechanisms would help reduce false...detection positives. The results of this research have been published in several peer-reviewed journal papers and a book chapter, and presented at a...project is to understand the fundamental mechanisms of the sensing properties of the semiconducting metal oxide nanowires in order to further improve

Smart Phones: Platform Enabling Modular, Chemical, Biological, and Explosives Sensing

DTIC Science & Technology

2013-07-01

Smart phones: Platform Enabling Modular, Chemical, Biological, and Explosives Sensing by Amethist S. Finch , Matthew Coppock, Justin R...Chemical, Biological, and Explosives Sensing Amethist S. Finch , Matthew Coppock, Justin R. Bickford, Marvin A. Conn, Thomas J. Proctor, and...Explosives Sensing 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Amethist S. Finch , Matthew Coppock, Justin R

Parallel array of independent thermostats for column separations

DOEpatents

Foret, Frantisek; Karger, Barry L.

2005-08-16

A thermostat array including an array of two or more capillary columns (10) or two or more channels in a microfabricated device is disclosed. A heat conductive material (12) surrounded each individual column or channel in array, each individual column or channel being thermally insulated from every other individual column or channel. One or more independently controlled heating or cooling elements (14) is positioned adjacent to individual columns or channels within the heat conductive material, each heating or cooling element being connected to a source of heating or cooling, and one or more independently controlled temperature sensing elements (16) is positioned adjacent to the individual columns or channels within the heat conductive material. Each temperature sensing element is connected to a temperature controller.

Molecular manipulations for enhancing luminescent bioreporters performance in the detection of toxic chemicals.

PubMed

Yagur-Kroll, Sharon; Belkin, Shimshon

2014-01-01

Microbial whole-cell bioreporters are genetically modified microorganisms that produce a quantifiable output in response to the presence of toxic chemicals or other stress factors. These bioreporters harbor a genetic fusion between a sensing element (usually a gene regulatory element responsive to the target) and a reporter element, the product of which may be quantitatively monitored either by its presence or by its activity. In this chapter we review genetic manipulations undertaken in order to improve bioluminescent bioreporter performance by increasing luminescent output, lowering the limit of detection, and shortening the response time. We describe molecular manipulations applied to all aspects of whole-cell bioreporters: the host strain, the expression system, the sensing element, and the reporter element. The molecular construction of whole-cell luminescent bioreporters, harboring fusions of gene promoter elements to reporter genes, has been around for over three decades; in most cases, these two genetic elements are combined "as is." This chapter outlines diverse molecular manipulations for enhancing the performance of such sensors.

Torsion sensing based on patterned piezoelectric beams

NASA Astrophysics Data System (ADS)

Cha, Youngsu; You, Hangil

2018-03-01

In this study, we investigated the sensing characteristics of piezoelectric beams under torsional loads. We used partially patterned piezoelectric beams to sense torsion. In particular, the piezoelectric patches are located symmetrically with respect to the line of the shear center of the beam. The patterned piezoelectric beam is modeled as a slender beam, and its electrical responses are obtained by piezoelectric electromechanical equations. To validate the modeling framework, experiments are performed using a setup that forces pure torsional deformation. Three different geometric configurations of the patterned piezoelectric layer are used for the experiments. The frequency and amplitude of the forced torsional load are systematically varied in order to study the behavior of the piezoelectric sensor. Experimental results demonstrate that two voltage outputs of the piezoelectric beam are approximately out of phase with identical amplitude. Moreover, the length of the piezoelectric layers has a significant influence on the sensing properties. Our theoretical predictions using the model support the experimental findings.

Leishmania amazonensis chemotaxis under glucose gradient studied by the strength and directionality of forces measured with optical tweezers

NASA Astrophysics Data System (ADS)

de Ysasa Pozzo, Liliana; Fontes, Adriana; de Thomaz, André A.; Barbosa, Luiz Carlos; Ayres, Diana Copi; Giorgio, Selma; Cesar, Carlos Lenz

2007-02-01

Chemotaxis is the mechanism microorganisms use to sense the environment surrounding them and to direct their movement towards attractive, or away from the repellent, chemicals. The biochemical sensing is almost the only way for communication between unicellular organisms. Prokaryote and Eukaryote chemotaxis has been mechanically studied mainly by observing the directionality and timing of the microorganisms movements subjected to a chemical gradient, but not through the directionality and strength of the forces it generates. To observe the vector force of microorganisms under a chemical gradient we developed a system composed of two large chambers connected by a tiny duct capable to keep the chemical gradient constant for more than ten hours. We also used the displacements of a microsphere trapped in an Optical Tweezers as the force transducer to measure the direction and the strength of the propulsion forces of flagellum of the microorganism under several gradient conditions. A 9μm diameter microsphere particle was trapped with a Nd:YAG laser and its movement was measured through the light scattered focused on a quadrant detector. We observed the behavior of the protozoa Leishmania amazonensis (eukaryote) under several glucose gradients. This protozoa senses the gradient around it by swimming in circles for three to five times following by tumbling, and not by the typical straight swimming/tumbling of bacteria. Our results also suggest that force direction and strength are also used to control its movement, not only the timing of swimming/tumbling, because we observed a higher force strength clearly directed towards the glucose gradient.

Structural design and output characteristic analysis of magnetostrictive tactile sensor for robotic applications

NASA Astrophysics Data System (ADS)

Zheng, Wendong; Wang, Bowen; Liu, Huaping; Li, Yunkai; Zhao, Ran; Weng, Ling; Zhang, Changgeng

2018-05-01

A novel magnetostrictive tactile sensor has been designed according to the transduction mechanism of cilia and Villari effect of iron-gallium alloy. The tactile sensor consists of a Galfenol beam, a pair of permanent magnets, a Hall sensor and a signal processing system. Compared with the conventional tactile sensor, our proposed tactile sensor can not only detect the contact-force, but also sense stiffness of an object. The performance and measurement range of tactile sensor have theoretically been analyzed and experimentally investigated. The results have revealed that the sensibility of tactile sensor for sensing force is up to 22.81mV/N at applied bias magnetic field of 2.56kA/m. Moreover, the sensor can effectively discriminate objects with different stiffness. The sensor is characterized by high sensitivity, good linearity, and quick response. It has the potential of being miniaturized and integrated into the finger of a robotic hand to realize force sensing and object recognition in real-time.

3-Axis Fully-Integrated Capacitive Tactile Sensor with Flip-Bonded CMOS on LTCC Interposer.

PubMed

Asano, Sho; Muroyama, Masanori; Nakayama, Takahiro; Hata, Yoshiyuki; Nonomura, Yutaka; Tanaka, Shuji

2017-10-25

This paper reports a 3-axis fully integrated differential capacitive tactile sensor surface-mountable on a bus line. The sensor integrates a flip-bonded complementary metal-oxide semiconductor (CMOS) with capacitive sensing circuits on a low temperature cofired ceramic (LTCC) interposer with Au through vias by Au-Au thermo-compression bonding. The CMOS circuit and bonding pads on the sensor backside were electrically connected through Au bumps and the LTCC interposer, and the differential capacitive gap was formed by an Au sealing frame. A diaphragm for sensing 3-axis force was formed in the CMOS substrate. The dimensions of the completed sensor are 2.5 mm in width, 2.5 mm in length, and 0.66 mm in thickness. The fabricated sensor output coded 3-axis capacitive sensing data according to applied 3-axis force by three-dimensional (3D)-printed pins. The measured sensitivity was as high as over 34 Count/mN for normal force and 14 to 15 Count/mN for shear force with small noise, which corresponds to less than 1 mN. The hysteresis and the average cross-sensitivity were also found to be less than 2% full scale and 11%, respectively.

3-Axis Fully-Integrated Capacitive Tactile Sensor with Flip-Bonded CMOS on LTCC Interposer †

PubMed Central

Asano, Sho; Nakayama, Takahiro; Hata, Yoshiyuki; Tanaka, Shuji

2017-01-01

This paper reports a 3-axis fully integrated differential capacitive tactile sensor surface-mountable on a bus line. The sensor integrates a flip-bonded complementary metal-oxide semiconductor (CMOS) with capacitive sensing circuits on a low temperature cofired ceramic (LTCC) interposer with Au through vias by Au-Au thermo-compression bonding. The CMOS circuit and bonding pads on the sensor backside were electrically connected through Au bumps and the LTCC interposer, and the differential capacitive gap was formed by an Au sealing frame. A diaphragm for sensing 3-axis force was formed in the CMOS substrate. The dimensions of the completed sensor are 2.5 mm in width, 2.5 mm in length, and 0.66 mm in thickness. The fabricated sensor output coded 3-axis capacitive sensing data according to applied 3-axis force by three-dimensional (3D)-printed pins. The measured sensitivity was as high as over 34 Count/mN for normal force and 14 to 15 Count/mN for shear force with small noise, which corresponds to less than 1 mN. The hysteresis and the average cross-sensitivity were also found to be less than 2% full scale and 11%, respectively. PMID:29068429

A Unique Self-Sensing, Self-Actuating AFM Probe at Higher Eigenmodes

PubMed Central

Wu, Zhichao; Guo, Tong; Tao, Ran; Liu, Leihua; Chen, Jinping; Fu, Xing; Hu, Xiaotang

2015-01-01

With its unique structure, the Akiyama probe is a type of tuning fork atomic force microscope probe. The long, soft cantilever makes it possible to measure soft samples in tapping mode. In this article, some characteristics of the probe at its second eigenmode are revealed by use of finite element analysis (FEA) and experiments in a standard atmosphere. Although the signal-to-noise ratio in this environment is not good enough, the 2 nm resolution and 0.09 Hz/nm sensitivity prove that the Akiyama probe can be used at its second eigenmode under FM non-contact mode or low amplitude FM tapping mode, which means that it is easy to change the measuring method from normal tapping to small amplitude tapping or non-contact mode with the same probe and equipment. PMID:26580619

Free-standing GaN grating couplers and rib waveguide for planar photonics at telecommunication wavelength

NASA Astrophysics Data System (ADS)

Liu, Qifa; Wang, Wei

2018-01-01

Gallium Nitride (GaN) free-standing planar photonic device at telecommunication wavelength based on GaN-on-silicon platform was presented. The free-standing structure was realized by particular double-side fabrication process, which combining GaN front patterning, Si substrate back releasing and GaN slab etching. The actual device parameters were identified via the physical characterizations employing scanning electron microscope (SEM), atomic force microscope (AFM) and reflectance spectra testing. High coupling efficiency and good light confinement properties of the gratings and rib waveguide at telecommunication wavelength range were verified by finite element method (FEM) simulation. This work illustrates the potential of new GaN photonic structure which will enable new functions for planar photonics in communication and sensing applications, and is favorable for the realization of integrated optical circuit.

[Notes for understanding the problem of "public" health in the health sector].

PubMed

Guimarães, Cristian Fabiano; da Silva, Rosane Azevedo Neves

2015-03-01

This paper presents a theoretical review of how the public health concept has been perceived in health practices, based on the problematic field introduced in Italian and Brazilian health reforms, in order to understand the construction of public health and the meanings that this term acquires in the health arena. The main goal is to understand how public health appears in the context of health movements in Italy and Brazil, as well as its movement of variation. In this sense, an attempt is made to identify elements that contribute to the composition of a genealogy of public health. From the investigation of public health practices, the tensions produced by this concept are analyzed, giving visibility to those practices that demonstrate the public health experience as a force in the world of health.

The force-sensing device region of α-catenin is an intrinsically disordered segment in the absence of intramolecular stabilization of the autoinhibitory form.

PubMed

Hirano, Yoshinori; Amano, Yu; Yonemura, Shigenobu; Hakoshima, Toshio

2018-05-01

Mechanotransduction by α-catenin facilitates the force-dependent development of adherens junctions (AJs) by recruiting vinculin to reinforce actin anchoring of AJs. The α-catenin mechanotransducing action is facilitated by its force-sensing device region that autoinhibits the vinculin-binding site 1 (VBS1). Here, we report the high-resolution structure of the force-sensing device region of α-catenin, which shows the autoinhibited form comprised of helix bundles E, F and G. The cryptic VBS1 is embedded into helix bundle E stabilized by direct interactions with the autoinhibitory region forming helix bundles F and G. Our molecular dissection study showed that helix bundles F and G are stable in solution in each isolated form, whereas helix bundle E that contains VBS1 is unstable and intrinsically disordered in solution in the isolated form. We successfully identified key residues mediating the autoinhibition and produced mutated α-catenins that display variable force sensitivity and autoinhibition. Using these mutants, we demonstrate both in vitro and in vivo that, in the absence of this stabilization, the helix bundle containing VBS1 would adopt an unfolded form, thus exposing VBS for vinculin binding. We provide evidence for importance of mechanotransduction with the intrinsic force sensitivity for vinculin recruitment to adherens junctions of epithelial cell sheets with mutated α-catenins. © 2018 Molecular Biology Society of Japan and John Wiley & Sons Australia, Ltd.

GelSight: High-Resolution Robot Tactile Sensors for Estimating Geometry and Force

PubMed Central

Yuan, Wenzhen; Dong, Siyuan; Adelson, Edward H.

2017-01-01

Tactile sensing is an important perception mode for robots, but the existing tactile technologies have multiple limitations. What kind of tactile information robots need, and how to use the information, remain open questions. We believe a soft sensor surface and high-resolution sensing of geometry should be important components of a competent tactile sensor. In this paper, we discuss the development of a vision-based optical tactile sensor, GelSight. Unlike the traditional tactile sensors which measure contact force, GelSight basically measures geometry, with very high spatial resolution. The sensor has a contact surface of soft elastomer, and it directly measures its deformation, both vertical and lateral, which corresponds to the exact object shape and the tension on the contact surface. The contact force, and slip can be inferred from the sensor’s deformation as well. Particularly, we focus on the hardware and software that support GelSight’s application on robot hands. This paper reviews the development of GelSight, with the emphasis in the sensing principle and sensor design. We introduce the design of the sensor’s optical system, the algorithm for shape, force and slip measurement, and the hardware designs and fabrication of different sensor versions. We also show the experimental evaluation on the GelSight’s performance on geometry and force measurement. With the high-resolution measurement of shape and contact force, the sensor has successfully assisted multiple robotic tasks, including material perception or recognition and in-hand localization for robot manipulation. PMID:29186053

Surprise and Sense Making: Undergraduate Placement Experiences in SMEs

ERIC Educational Resources Information Center

Walmsley, Andreas; Thomas, Rhodri; Jameson, Stephanie

2006-01-01

Purpose: This paper seeks to explore undergraduate placement experiences in tourism and hospitality SMEs, focusing on the notions of surprise and sense making. It aims to argue that surprises and sense making are important elements not only of the adjustment process when entering new work environments, but also of the learning experience that…

Development of Finite Elements for Two-Dimensional Structural Analysis Using the Integrated Force Method

NASA Technical Reports Server (NTRS)

Kaljevic, Igor; Patnaik, Surya N.; Hopkins, Dale A.

1996-01-01

The Integrated Force Method has been developed in recent years for the analysis of structural mechanics problems. This method treats all independent internal forces as unknown variables that can be calculated by simultaneously imposing equations of equilibrium and compatibility conditions. In this paper a finite element library for analyzing two-dimensional problems by the Integrated Force Method is presented. Triangular- and quadrilateral-shaped elements capable of modeling arbitrary domain configurations are presented. The element equilibrium and flexibility matrices are derived by discretizing the expressions for potential and complementary energies, respectively. The displacement and stress fields within the finite elements are independently approximated. The displacement field is interpolated as it is in the standard displacement method, and the stress field is approximated by using complete polynomials of the correct order. A procedure that uses the definitions of stress components in terms of an Airy stress function is developed to derive the stress interpolation polynomials. Such derived stress fields identically satisfy the equations of equilibrium. Moreover, the resulting element matrices are insensitive to the orientation of local coordinate systems. A method is devised to calculate the number of rigid body modes, and the present elements are shown to be free of spurious zero-energy modes. A number of example problems are solved by using the present library, and the results are compared with corresponding analytical solutions and with results from the standard displacement finite element method. The Integrated Force Method not only gives results that agree well with analytical and displacement method results but also outperforms the displacement method in stress calculations.

Sensing mode coupling analysis for dual-mass MEMS gyroscope and bandwidth expansion within wide-temperature range

NASA Astrophysics Data System (ADS)

Cao, Huiliang; Li, Hongsheng; Shao, Xingling; Liu, Zhiyu; Kou, Zhiwei; Shan, Yanhu; Shi, Yunbo; Shen, Chong; Liu, Jun

2018-01-01

This paper presents the bandwidth expanding method with wide-temperature range for sense mode coupling dual-mass MEMS gyro. The real sensing mode of the gyroscope is analyzed to be the superposition of in-phase and anti-phase sensing modes. The mechanical sensitivity and bandwidth of the gyroscope structure are conflicted with each other and both governed by the frequency difference between sensing and drive modes (min {Δω1, Δω2}). The sensing mode force rebalancing combs stimulation method (FRCSM) is presented to simulate the Coriolis force, and based on this method, the gyro's dynamic characteristics are tested. The sensing closed- loop controller is achieved by operational amplifier based on phase lead method, which enable the magnitude margin and phase margin of the system to reach 7.21 dB and 34.6° respectively, and the closed-loop system also expands gyro bandwidth from 13 Hz (sensing open-loop) to 102 Hz (sensing closed-loop). What's more, the turntable test results show that the sensing closed-loop works stably in wide-temperature range (from -40 °C to 60 °C) and the bandwidth values are 107 Hz @-40 °C and 97 Hz @60 °C. The results indicate that the higher temperature causes lower bandwidth, and verify the simulation results are 103 Hz @-40 °C and 98.2 Hz @60 °C. The new bottleneck of the closed loop bandwidth is the valley generated by conjugate zeros, which is formed by superposition of sensing modes.

Isolated resonator gyroscope with isolation trimming using a secondary element

NASA Technical Reports Server (NTRS)

Challoner, A. Dorian (Inventor); Shcheglov, Kirill V. (Inventor)

2006-01-01

The present invention discloses a resonator gyroscope including an isolated resonator. One or more flexures support the isolated resonator and a baseplate is affixed to the resonator by the flexures. Drive and sense elements are affixed to the baseplate and used to excite the resonator and sense movement of the gyroscope. In addition, at least one secondary element (e.g., another electrode) is affixed to the baseplate and used for trimming isolation of the resonator. The resonator operates such that it transfers substantially no net momentum to the baseplate when the resonator is excited. Typically, the isolated resonator comprises a proof mass and a counterbalancing plate.

Solid State Carbon Monoxide Sensor

NASA Technical Reports Server (NTRS)

Upchurch, Billy T. (Inventor); Wood, George M. (Inventor); Schryer, David R. (Inventor); Leighty, Bradley D. (Inventor); Oglesby, Donald M. (Inventor); Kielin, Erik J. (Inventor); Brown, Kenneth G. (Inventor); DAmbrosia, Christine M. (Inventor)

1999-01-01

A means for detecting carbon monoxide which utilizes an un-heated catalytic material to oxidize carbon monoxide at ambient temperatures. Because this reaction is exothermic, a thermistor in contact with the catalytic material is used as a sensing element to detect the heat evolved as carbon monoxide is oxidized to carbon dioxide at the catalyst surface, without any heaters or external heating elements for the ambient air or catalytic element material. Upon comparison to a reference thermistor, relative increases in the temperature of the sensing thermistor correspond positively with an increased concentration of carbon monoxide in the ambient medium and are thus used as an indicator of the presence of carbon monoxide.

Coupling between apical tension and basal adhesion allow epithelia to collectively sense and respond to substrate topography over long distances.

PubMed

Broaders, Kyle E; Cerchiari, Alec E; Gartner, Zev J

2015-12-01

Epithelial sheets fold into complex topographies that contribute to their function in vivo. Cells can sense and respond to substrate topography in their immediate vicinity by modulating their interfacial mechanics, but the extent to which these mechanical properties contribute to their ability to sense substrate topography across length scales larger than a single cell has not been explored in detail. To study the relationship between the interfacial mechanics of single cells and their collective behavior as tissues, we grew cell-sheets on substrates engraved with surface features spanning macroscopic length-scales. We found that many epithelial cell-types sense and respond to substrate topography, even when it is locally nearly planar. Cells clear or detach from regions of local negative curvature, but not from regions with positive or no curvature. We investigated this phenomenon using a finite element model where substrate topography is coupled to epithelial response through a balance of tissue contractility and adhesive forces. The model correctly predicts the focal sites of cell-clearing and epithelial detachment. Furthermore, the model predicts that local tissue response to substrate curvature is a function of the surrounding topography of the substrate across long distances. Analysis of cell-cell and cell-substrate contact angles suggests a relationship between these single-cell interfacial properties, epithelial interfacial properties, and collective epithelial response to substrate topography. Finally, we show that contact angles change upon activation of oncogenes or inhibition of cell-contractility, and that these changes correlate with collective epithelial response. Our results demonstrate that in mechanically integrated epithelial sheets, cell contractility can be transmitted through multiple cells and focused by substrate topography to affect a behavioral response at distant sites.

Fiber optic sensors based on hybrid phenyl-silica xerogel films to detect n-hexane: determination of the isosteric enthalpy of adsorption.

PubMed

Echeverría, Jesús C; Calleja, Ignacio; Moriones, Paula; Garrido, Julián J

2017-01-01

We investigated the response of three fiber optic sensing elements prepared at pH 10 from phenyltriethoxysilane (PhTEOS) and tetraethylsilane (TEOS) mixtures with 30, 40, and 50% PhTEOS in the silicon precursor mixture. The sensing elements are referred to as Ph30, Ph40 and Ph50, respectively. The films were synthesized by the sol-gel method and affixed to the end of optical fibers by the dip-coating technique. Fourier transform infrared spectroscopy, N 2 adsorption-desorption at 77 K and X-ray diffraction analysis were used to characterize the xerogels. At a given pressure of n -hexane, the response of each sensing element decreased with temperature, indicating an exothermic process that confirmed the role of adsorption in the overall performance of the sensing elements. The isosteric adsorption enthalpies were obtained from the calibration curves at different temperatures. The magnitude of the isosteric enthalpy of n -hexane increased with the relative response and reached a plateau that stabilized at approximately -31 kJ mol -1 for Ph40 and Ph50 and at approximately -37 kJ mol -1 for Ph30. This indicates that the adsorbate-adsorbent interaction was dominant at lower relative pressure and condensation of the adsorbate on the mesopores was dominant at higher relative pressure.

Fiber optic sensors based on hybrid phenyl-silica xerogel films to detect n-hexane: determination of the isosteric enthalpy of adsorption

PubMed Central

Calleja, Ignacio; Moriones, Paula; Garrido, Julián J

2017-01-01

We investigated the response of three fiber optic sensing elements prepared at pH 10 from phenyltriethoxysilane (PhTEOS) and tetraethylsilane (TEOS) mixtures with 30, 40, and 50% PhTEOS in the silicon precursor mixture. The sensing elements are referred to as Ph30, Ph40 and Ph50, respectively. The films were synthesized by the sol–gel method and affixed to the end of optical fibers by the dip-coating technique. Fourier transform infrared spectroscopy, N2 adsorption–desorption at 77 K and X-ray diffraction analysis were used to characterize the xerogels. At a given pressure of n-hexane, the response of each sensing element decreased with temperature, indicating an exothermic process that confirmed the role of adsorption in the overall performance of the sensing elements. The isosteric adsorption enthalpies were obtained from the calibration curves at different temperatures. The magnitude of the isosteric enthalpy of n-hexane increased with the relative response and reached a plateau that stabilized at approximately −31 kJ mol−1 for Ph40 and Ph50 and at approximately −37 kJ mol−1 for Ph30. This indicates that the adsorbate–adsorbent interaction was dominant at lower relative pressure and condensation of the adsorbate on the mesopores was dominant at higher relative pressure. PMID:28326238

Increasing the Sensitivity of Surface Acoustic Wave (SAW) Chemical Sensors and other Chemical Sensing Investigations

DTIC Science & Technology

2010-03-01

are those of the author and do not reflect the official policy or position of the United States Air Force, Department of Defense, or the U.S...device recovers to a neutral state [8]. 2.1.2 Sensing Methods There are many methods of using acoustic waves for sensing applications. Some of the

ATRAN Terrain Sensing Guidance-The Grand-Daddy System

NASA Astrophysics Data System (ADS)

Koch, Richard F.; Evans, Donald C.

1980-12-01

ATRAN was the pioneer terrain sensing guidance system developed in the 1950 era and deployed in Europe on the Air Force's mobile, ground launched TM-76A MACE cruise missile in the late 1950's and early 1960's. The background, principles and technology are described for this system which was the forerunner of todays modern autonomous standoff terrain sensing guided weapons.

Flexible and self-powered temperature-pressure dual-parameter sensors using microstructure-frame-supported organic thermoelectric materials.

PubMed

Zhang, Fengjiao; Zang, Yaping; Huang, Dazhen; Di, Chong-an; Zhu, Daoben

2015-09-21

Skin-like temperature- and pressure-sensing capabilities are essential features for the next generation of artificial intelligent products. Previous studies of e-skin and smart elements have focused on flexible pressure sensors, whereas the simultaneous and sensitive detection of temperature and pressure with a single device remains a challenge. Here we report developing flexible dual-parameter temperature-pressure sensors based on microstructure-frame-supported organic thermoelectric (MFSOTE) materials. The effective transduction of temperature and pressure stimuli into two independent electrical signals permits the instantaneous sensing of temperature and pressure with an accurate temperature resolution of <0.1 K and a high-pressure-sensing sensitivity of up to 28.9 kPa(-1). More importantly, these dual-parameter sensors can be self-powered with outstanding sensing performance. The excellent sensing properties of MFSOTE-based devices, together with their unique advantages of low cost and large-area fabrication, make MFSOTE materials possess promising applications in e-skin and health-monitoring elements.

Flexible and self-powered temperature-pressure dual-parameter sensors using microstructure-frame-supported organic thermoelectric materials

NASA Astrophysics Data System (ADS)

Zhang, Fengjiao; Zang, Yaping; Huang, Dazhen; di, Chong-An; Zhu, Daoben

2015-09-01

Skin-like temperature- and pressure-sensing capabilities are essential features for the next generation of artificial intelligent products. Previous studies of e-skin and smart elements have focused on flexible pressure sensors, whereas the simultaneous and sensitive detection of temperature and pressure with a single device remains a challenge. Here we report developing flexible dual-parameter temperature-pressure sensors based on microstructure-frame-supported organic thermoelectric (MFSOTE) materials. The effective transduction of temperature and pressure stimuli into two independent electrical signals permits the instantaneous sensing of temperature and pressure with an accurate temperature resolution of <0.1 K and a high-pressure-sensing sensitivity of up to 28.9 kPa-1. More importantly, these dual-parameter sensors can be self-powered with outstanding sensing performance. The excellent sensing properties of MFSOTE-based devices, together with their unique advantages of low cost and large-area fabrication, make MFSOTE materials possess promising applications in e-skin and health-monitoring elements.

Combination radial and thrust magnetic bearing

NASA Technical Reports Server (NTRS)

Blumenstock, Kenneth A. (Inventor)

2002-01-01

A combination radial and thrust magnetic bearing is disclosed that allows for both radial and thrust axes control of an associated shaft. The combination radial and thrust magnetic bearing comprises a rotor and a stator. The rotor comprises a shaft, and first and second rotor pairs each having respective rotor elements. The stator comprises first and second stator elements and a magnet-sensor disk. In one embodiment, each stator element has a plurality of split-poles and a corresponding plurality of radial force coils and, in another embodiment, each stator element does not require thrust force coils, and radial force coils are replaced by double the plurality of coils serving as an outer member of each split-pole half.

Array-type NH.sub.3 sensor

DOEpatents

West, David Lawrence; Montgomery, Frederick Charles; Armstrong, Timothy R; Warmack, Robert J

2013-12-31

An array-type sensor that senses NH.sub.3 includes non-Nernstian sensing elements constructed from metal and/or metal-oxide electrodes on an O.sub.2 ion conducting substrate. In one example sensor, one electrode may be made of platinum, another electrode may be made of manganese (III) oxide (Mn.sub.2O.sub.3), and another electrode may be made of tungsten trioxide (WO.sub.3). Some sensing elements may further include an electrode made of La.sub.0.6Sr.sub.0.4Co.sub.0.2Fe.sub0.8O.sub.3 and another electrode made of LaCr.sub.0.95.Mg.sub.0.05O.sub.3.

AMTV headway sensor and safety design

NASA Technical Reports Server (NTRS)

Johnston, A. R.; Nelson, M.; Cassell, P.; Herridge, J. T.

1980-01-01

A headway sensing system for an automated mixed traffic vehicle (AMTV) employing an array of optical proximity sensor elements is described, and its performance is presented in terms of object detection profiles. The problem of sensing in turns is explored experimentally and requirements for future turn sensors are discussed. A recommended headway sensor configuration, employing multiple source elements in the focal plane of one lens operating together with a similar detector unit, is described. Alternative concepts including laser radar, ultrasonic sensing, imaging techniques, and radar are compared to the present proximity sensor approach. Design concepts for an AMTV body which will minimize the probability of injury to pedestrians or passengers in the event of a collision are presented.

Visual force sensing with flexible nanowire buckling springs

NASA Astrophysics Data System (ADS)

Dobrokhotov, Vladimir V.; Yazdanpanah, Mehdi M.; Pabba, Santosh; Safir, Abdelilah; Cohn, Robert W.

2008-01-01

A calibrated method of force sensing is demonstrated in which the buckled shape of a long flexible metallic nanowire, referred to as a 'nanoneedle', is interpreted to determine the applied force. An individual needle of 157 nm diameter by 15.6 µm length is grown on an atomic force microscope (AFM) cantilever with a desired orientation (by the method of Yazdanpanah et al 2005 J. Appl. Phys. 98 073510). Using a nanomanipulator the needle is buckled in the chamber of a scanning electron microscope (SEM) and the buckled shapes are recorded in SEM images. Force is determined as a function of deflection for an assumed elastic modulus by fitting the shapes using the generalized elastica model (De Bona and Zelenika 1997 Proc. Inst. Mech. Eng. C 211 509-17). In this calibration the elastic modulus (68.3 GPa) was determined using an auxiliary AFM measurement, with the needle in the same orientation as in the SEM. Following this calibration the needle was used as a sensor in a different orientation than the AFM coordinates to deflect a suspended PLLA polymer fiber from which the elastic modulus (2.96 GPa) was determined. The practical value of the sensing method does depend on the reliability and ruggedness of the needle. In this study the same needle remained rigidly secured to the AFM cantilever throughout the entire SEM/AFM calibration procedure and the characterization of the nanofiber.

Ice Detection and Mitigation Device

NASA Technical Reports Server (NTRS)

Gambino, Richard J. (Inventor); Gouldstone, Christopher (Inventor); Gutleber, Jonathan (Inventor); Hubble, David (Inventor); Trelewicz, Jason (Inventor)

2016-01-01

A method for deicing an aerostructure includes driving a sensing current through a heater element coated to an aerostructure, the heater element having a resistance that is temperature dependent. A resistance of the heater element is monitored. It is determined whether there is icing at the heater element using the monitored resistance of the heater element. A melting current is driven through the heater element when it is determined that there is icing at the heater element.

Highly Sensitive and Wide-Dynamic-Range Multichannel Optical-Fiber pH Sensor Based on PWM Technique.

PubMed

Khan, Md Rajibur Rahaman; Kang, Shin-Won

2016-11-09

In this study, we propose a highly sensitive multichannel pH sensor that is based on an optical-fiber pulse width modulation (PWM) technique. According to the optical-fiber PWM method, the received sensing signal's pulse width changes when the optical-fiber pH sensing-element of the array comes into contact with pH buffer solutions. The proposed optical-fiber PWM pH-sensing system offers a linear sensing response over a wide range of pH values from 2 to 12, with a high pH-sensing ability. The sensitivity of the proposed pH sensor is 0.46 µs/pH, and the correlation coefficient R² is approximately 0.997. Additional advantages of the proposed optical-fiber PWM pH sensor include a short/fast response-time of about 8 s, good reproducibility properties with a relative standard deviation (RSD) of about 0.019, easy fabrication, low cost, small size, reusability of the optical-fiber sensing-element, and the capability of remote sensing. Finally, the performance of the proposed PWM pH sensor was compared with that of potentiometric, optical-fiber modal interferometer, and optical-fiber Fabry-Perot interferometer pH sensors with respect to dynamic range width, linearity as well as response and recovery times. We observed that the proposed sensing systems have better sensing abilities than the above-mentioned pH sensors.

Highly Sensitive and Wide-Dynamic-Range Multichannel Optical-Fiber pH Sensor Based on PWM Technique

PubMed Central

Khan, Md. Rajibur Rahaman; Kang, Shin-Won

2016-01-01

In this study, we propose a highly sensitive multichannel pH sensor that is based on an optical-fiber pulse width modulation (PWM) technique. According to the optical-fiber PWM method, the received sensing signal’s pulse width changes when the optical-fiber pH sensing-element of the array comes into contact with pH buffer solutions. The proposed optical-fiber PWM pH-sensing system offers a linear sensing response over a wide range of pH values from 2 to 12, with a high pH-sensing ability. The sensitivity of the proposed pH sensor is 0.46 µs/pH, and the correlation coefficient R2 is approximately 0.997. Additional advantages of the proposed optical-fiber PWM pH sensor include a short/fast response-time of about 8 s, good reproducibility properties with a relative standard deviation (RSD) of about 0.019, easy fabrication, low cost, small size, reusability of the optical-fiber sensing-element, and the capability of remote sensing. Finally, the performance of the proposed PWM pH sensor was compared with that of potentiometric, optical-fiber modal interferometer, and optical-fiber Fabry–Perot interferometer pH sensors with respect to dynamic range width, linearity as well as response and recovery times. We observed that the proposed sensing systems have better sensing abilities than the above-mentioned pH sensors. PMID:27834865

Multichannel optical sensing device

DOEpatents

Selkowitz, S.E.

1985-08-16

A multichannel optical sensing device is disclosed, for measuring the outdoor sky luminance or illuminance or the luminance or illuminance distribution in a room, comprising a plurality of light receptors, an optical shutter matrix including a plurality of liquid crystal optical shutter elements operable by electrical control signals between light transmitting and light stopping conditions, fiber optical elements connected between the receptors and the shutter elements, a microprocessor based programmable control unit for selectively supplying control signals to the optical shutter elements in a programmable sequence, a photodetector including an optical integrating spherical chamber having an input port for receiving the light from the shutter matrix and at least one detector element in the spherical chamber for producing output signals corresponding to the light, and output units for utilizing the output signals including a storage unit having a control connection to the microprocessor based programmable control unit for storing the output signals under the sequence control of the programmable control unit.

Multichannel optical sensing device

DOEpatents

Selkowitz, Stephen E.

1990-01-01

A multichannel optical sensing device is disclosed, for measuring the outr sky luminance or illuminance or the luminance or illuminance distribution in a room, comprising a plurality of light receptors, an optical shutter matrix including a plurality of liquid crystal optical shutter elements operable by electrical control signals between light transmitting and light stopping conditions, fiber optic elements connected between the receptors and the shutter elements, a microprocessor based programmable control unit for selectively supplying control signals to the optical shutter elements in a programmable sequence, a photodetector including an optical integrating spherical chamber having an input port for receiving the light from the shutter matrix and at least one detector element in the spherical chamber for producing output signals corresponding to the light, and output units for utilizing the output signals including a storage unit having a control connection to the microprocessor based programmable control unit for storing the output signals under the sequence control of the programmable control unit.

The design and implementation of a windowing interface pinch force measurement system

NASA Astrophysics Data System (ADS)

Ho, Tze-Yee; Chen, Yuanu-Joan; Chung, Chin-Teng; Hsiao, Ming-Heng

2010-02-01

This paper presents a novel windowing interface pinch force measurement system that is basically based on an USB (Universal Series Bus) microcontroller which mainly processes the sensing data from the force sensing resistance sensors mounted on five digits. It possesses several friendly functions, such as the value and curve trace of the applied force by a hand injured patient displayed in real time on a monitoring screen, consequently, not only the physician can easily evaluate the effect of hand injury rehabilitation, but also the patients get more progressive during the hand physical therapy by interacting with the screen of pinch force measurement. In order to facilitate the pinch force measurement system and make it friendly, the detail hardware design and software programming flowchart are described in this paper. Through a series of carefully and detailed experimental tests, first of all, the relationship between the applying force and the FSR sensors are measured and verified. Later, the different type of pinch force measurements are verified by the oscilloscope and compared with the corresponding values and waveform traces in the window interface display panel to obtain the consistency. Finally, a windowing interface pinch force measurement system based on the USB microcontroller is implemented and demonstrated. The experimental results show the verification and feasibility of the designed system.

Piezoresistive in-line integrated force sensors for on-chip measurement and control

NASA Astrophysics Data System (ADS)

Teichert, Kendall; Waterfall, Tyler; Jensen, Brian; Howell, Larry; McLain, Tim

2007-04-01

This paper presents the design, fabrication, and testing of a force sensor for integrated use with thermomechanical in-plane microactuators. The force sensor is designed to be integrated with the actuator and fabricated in the same batch fabrication process. This sensor uses the piezoresistive property of silicon as a sensing signal by directing the actuation force through two thin legs, producing a tensile stress. This tensile load produces a resistance change in the thin legs by the piezoresistive effect. The resistance change is linearly correlated with the applied force. The device presented was designed by considering both its piezoresistive sensitivity and out-of- plane torsional stability. A design trade-off exists between these two objectives in that longer legs are more sensitive yet less stable. Fabrication of the sensor design was done using the MUMPs process. This paper presents experimental results from this device and a basic model for comparison with previously attained piezoresistive data. The results validate the concept of integral sensing using the piezoresistive property of silicon.

Detection of Membrane Puncture with Haptic Feedback using a Tip-Force Sensing Needle.

PubMed

Elayaperumal, Santhi; Bae, Jung Hwa; Daniel, Bruce L; Cutkosky, Mark R

2014-09-01

This paper presents calibration and user test results of a 3-D tip-force sensing needle with haptic feedback. The needle is a modified MRI-compatible biopsy needle with embedded fiber Bragg grating (FBG) sensors for strain detection. After calibration, the needle is interrogated at 2 kHz, and dynamic forces are displayed remotely with a voice coil actuator. The needle is tested in a single-axis master/slave system, with the voice coil haptic display at the master, and the needle at the slave end. Tissue phantoms with embedded membranes were used to determine the ability of the tip-force sensors to provide real-time haptic feedback as compared to external sensors at the needle base during needle insertion via the master/slave system. Subjects were able to determine the position of the embedded membranes with significantly better accuracy using FBG tip feedback than with base feedback using a commercial force/torque sensor (p = 0.045) or with no added haptic feedback (p = 0.0024).

Detection of Membrane Puncture with Haptic Feedback using a Tip-Force Sensing Needle

PubMed Central

Elayaperumal, Santhi; Bae, Jung Hwa; Daniel, Bruce L.; Cutkosky, Mark R.

2015-01-01

This paper presents calibration and user test results of a 3-D tip-force sensing needle with haptic feedback. The needle is a modified MRI-compatible biopsy needle with embedded fiber Bragg grating (FBG) sensors for strain detection. After calibration, the needle is interrogated at 2 kHz, and dynamic forces are displayed remotely with a voice coil actuator. The needle is tested in a single-axis master/slave system, with the voice coil haptic display at the master, and the needle at the slave end. Tissue phantoms with embedded membranes were used to determine the ability of the tip-force sensors to provide real-time haptic feedback as compared to external sensors at the needle base during needle insertion via the master/slave system. Subjects were able to determine the position of the embedded membranes with significantly better accuracy using FBG tip feedback than with base feedback using a commercial force/torque sensor (p = 0.045) or with no added haptic feedback (p = 0.0024). PMID:26509101

The biomechanical effects of variation in the maximum forces exerted by trunk muscles on the joint forces and moments in the lumbar spine: a finite element analysis.

PubMed

Kim, K; Lee, S K; Kim, Y H

2010-10-01

The weakening of trunk muscles is known to be related to a reduction of the stabilization function provided by the muscles to the lumbar spine; therefore, strengthening deep muscles might reduce the possibility of injury and pain in the lumbar spine. In this study, the effect of variation in maximum forces of trunk muscles on the joint forces and moments in the lumbar spine was investigated. Accordingly, a three-dimensional finite element model of the lumbar spine that included the trunk muscles was used in this study. The variation in maximum forces of specific muscle groups was then modelled, and joint compressive and shear forces, as well as resultant joint moments, which were presumed to be related to spinal stabilization from a mechanical viewpoint, were analysed. The increase in resultant joint moments occurred owing to decrease in maximum forces of the multifidus, interspinales, intertransversarii, rotatores, iliocostalis, longissimus, psoas, and quadratus lumborum. In addition, joint shear forces and resultant joint moments were reduced as the maximum forces of deep muscles were increased. These results from finite element analysis indicate that the variation in maximum forces exerted by trunk muscles could affect the joint forces and joint moments in the lumbar spine.

10-fold detection range increase in quadrant-photodiode position sensing for photonic force microscope

NASA Astrophysics Data System (ADS)

Perrone, Sandro; Volpe, Giovanni; Petrov, Dmitri

2008-10-01

We propose a technique that permits one to increase by one order of magnitude the detection range of position sensing for the photonic force microscope with quadrant photodetectors (QPDs). This technique takes advantage of the unavoidable cross-talk between output signals of the QPD and does not assume that the output signals are linear in the probe displacement. We demonstrate the increase in the detection range from 150 to 1400 nm for a trapped polystyrene sphere with radius of 300 nm as probe.

10-fold detection range increase in quadrant-photodiode position sensing for photonic force microscope

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

Perrone, Sandro; Volpe, Giovanni; Petrov, Dmitri

2008-10-15

We propose a technique that permits one to increase by one order of magnitude the detection range of position sensing for the photonic force microscope with quadrant photodetectors (QPDs). This technique takes advantage of the unavoidable cross-talk between output signals of the QPD and does not assume that the output signals are linear in the probe displacement. We demonstrate the increase in the detection range from 150 to 1400 nm for a trapped polystyrene sphere with radius of 300 nm as probe.

10-fold detection range increase in quadrant-photodiode position sensing for photonic force microscope.

PubMed

Perrone, Sandro; Volpe, Giovanni; Petrov, Dmitri

2008-10-01

We propose a technique that permits one to increase by one order of magnitude the detection range of position sensing for the photonic force microscope with quadrant photodetectors (QPDs). This technique takes advantage of the unavoidable cross-talk between output signals of the QPD and does not assume that the output signals are linear in the probe displacement. We demonstrate the increase in the detection range from 150 to 1400 nm for a trapped polystyrene sphere with radius of 300 nm as probe.

Temperature, stress, and corrosive sensing apparatus utilizing harmonic response of magnetically soft sensor element (s)

NASA Technical Reports Server (NTRS)

Grimes, Craig A. (Inventor); Ong, Keat Ghee (Inventor)

2003-01-01

A temperature sensing apparatus including a sensor element made of a magnetically soft material operatively arranged within a first and second time-varying interrogation magnetic field, the first time-varying magnetic field being generated at a frequency higher than that for the second magnetic field. A receiver, remote from the sensor element, is engaged to measure intensity of electromagnetic emissions from the sensor element to identify a relative maximum amplitude value for each of a plurality of higher-order harmonic frequency amplitudes so measured. A unit then determines a value for temperature (or other parameter of interst) using the relative maximum harmonic amplitude values identified. In other aspects of the invention, the focus is on an apparatus and technique for determining a value for of stress condition of a solid analyte and for determining a value for corrosion, using the relative maximum harmonic amplitude values identified. A magnetically hard element supporting a biasing field adjacent the magnetically soft sensor element can be included.

Finite Element Analysis Of Influence Of Flank Wear Evolution On Forces In Orthogonal Cutting Of 42CrMo4 Steel

NASA Astrophysics Data System (ADS)

Madajewski, Marek; Nowakowski, Zbigniew

2017-01-01

This paper presents analysis of flank wear influence on forces in orthogonal turning of 42CrMo4 steel and evaluates capacity of finite element model to provide such force values. Data about magnitude of feed and cutting force were obtained from measurements with force tensiometer in experimental test as well as from finite element analysis of chip formation process in ABAQUS/Explicit software. For studies an insert with complex rake face was selected and flank wear was simulated by grinding operation on its flank face. The aim of grinding inset surface was to obtain even flat wear along cutting edge, which after the measurement could be modeled with CAD program and applied in FE analysis for selected range of wear width. By comparing both sets of force values as function of flank wear in given cutting conditions FEA model was validated and it was established that it can be applied to analyze other physical aspects of machining. Force analysis found that progression of wear causes increase in cutting force magnitude and steep boost to feed force magnitude. Analysis of Fc/Ff force ratio revealed that flank wear has significant impact on resultant force in orthogonal cutting and magnitude of this force components in cutting and feed direction. Surge in force values can result in transfer of substantial loads to machine-tool interface.

Analysis and modeling of the seasonal South China Sea temperature cycle using remote sensing

NASA Astrophysics Data System (ADS)

Twigt, Daniel J.; de Goede, Erik D.; Schrama, Ernst J. O.; Gerritsen, Herman

2007-10-01

The present paper describes the analysis and modeling of the South China Sea (SCS) temperature cycle on a seasonal scale. It investigates the possibility to model this cycle in a consistent way while not taking into account tidal forcing and associated tidal mixing and exchange. This is motivated by the possibility to significantly increase the model’s computational efficiency when neglecting tides. The goal is to develop a flexible and efficient tool for seasonal scenario analysis and to generate transport boundary forcing for local models. Given the significant spatial extent of the SCS basin and the focus on seasonal time scales, synoptic remote sensing is an ideal tool in this analysis. Remote sensing is used to assess the seasonal temperature cycle to identify the relevant driving forces and is a valuable source of input data for modeling. Model simulations are performed using a three-dimensional baroclinic-reduced depth model, driven by monthly mean sea surface anomaly boundary forcing, monthly mean lateral temperature, and salinity forcing obtained from the World Ocean Atlas 2001 climatology, six hourly meteorological forcing from the European Center for Medium range Weather Forecasting ERA-40 dataset, and remotely sensed sea surface temperature (SST) data. A sensitivity analysis of model forcing and coefficients is performed. The model results are quantitatively assessed against climatological temperature profiles using a goodness-of-fit norm. In the deep regions, the model results are in good agreement with this validation data. In the shallow regions, discrepancies are found. To improve the agreement there, we apply a SST nudging method at the free water surface. This considerably improves the model’s vertical temperature representation in the shallow regions. Based on the model validation against climatological in situ and SST data, we conclude that the seasonal temperature cycle for the deep SCS basin can be represented to a good degree. For shallow regions, the absence of tidal mixing and exchange has a clear impact on the model’s temperature representation. This effect on the large-scale temperature cycle can be compensated to a good degree by SST nudging for diagnostic applications.

Simple method for self-referenced and lable-free biosensing by using a capillary sensing element.

PubMed

Liu, Yun; Chen, Shimeng; Liu, Qiang; Liu, Zigeng; Wei, Peng

2017-05-15

We demonstrated a simple method for self-reference and label free biosensing based on a capillary sensing element and common optoelectronic devices. The capillary sensing element is illuminated by a light-emitting diode (LED) light source and detected by a webcam. Part of gold film that deposited on the tubing wall is functionalized to carry on the biological information in the excited SPR modes. The end face of the capillary was monitored and separate regions of interest (ROIs) were selected as the measurement channel and the reference channel. In the ROIs, the biological information can be accurately extracted from the image by simple image processing. Moreover, temperature fluctuation, bulk RI fluctuation, light source fluctuation and other factors can be effectively compensated during detection. Our biosensing device has a sensitivity of 1145%/RIU and a resolution better than 5.287 × 10 -4 RIU, considering a 0.79% noise level. We apply it for concanavalin A (Con A) biological measurement, which has an approximately linear response to the specific analyte concentration. This simple method provides a new approach for multichannel SPR sensing and reference-compensated calibration of SPR signal for label-free detection.

Optimization of Actuating Origami Networks

NASA Astrophysics Data System (ADS)

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

2015-03-01

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

Tunnel effect measuring systems and particle detectors

NASA Technical Reports Server (NTRS)

Kaiser, William J. (Inventor); Waltman, Steven B. (Inventor); Kenny, Thomas W. (Inventor)

1994-01-01

Methods and apparatus for measuring gravitational and inertial forces, magnetic fields, or wave or radiant energy acting on an object or fluid in space provide an electric tunneling current through a gap between an electrode and that object or fluid in space and vary that gap with any selected one of such forces, magnetic fields, or wave or radiant energy acting on that object or fluid. These methods and apparatus sense a corresponding variation in an electric property of that gap and determine the latter force, magnetic fields, or wave or radiant energy in response to that corresponding variation, and thereby sense or measure such parameters as acceleration, position, particle mass, velocity, magnetic field strength, presence or direction, or wave or radiant energy intensity, presence or direction.

Tunnel effect measuring systems and particle detectors

NASA Technical Reports Server (NTRS)

Kaiser, William J. (Inventor); Waltman, Steven B. (Inventor); Kenny, Thomas W. (Inventor)

1993-01-01

Methods and apparatus for measuring gravitational and inertial forces, magnetic fields, or wave or radiant energy acting on an object or fluid in space provide an electric tunneling current through a gap between an electrode and that object or fluid in space and vary that gap with any selected one of such forces, magnetic fields, or wave or radiant energy acting on that object or fluid. These methods and apparatus sense a corresponding variation in an electric property of that gap and determine the latter force, magnetic fields, or wave or radiant energy in response to that corresponding variation, and thereby sense or measure such parameters as acceleration, position, particle mass, velocity, magnetic field strength, presence or direction, or wave or radiant energy intensity, presence or direction.

Tunnel effect wave energy detection

NASA Technical Reports Server (NTRS)

Kaiser, William J. (Inventor); Waltman, Steven B. (Inventor); Kenny, Thomas W. (Inventor)

1995-01-01

Methods and apparatus for measuring gravitational and inertial forces, magnetic fields, or wave or radiant energy acting on an object or fluid in space provide an electric tunneling current through a gap between an electrode and that object or fluid in space and vary that gap with any selected one of such forces, magnetic fields, or wave or radiant energy acting on that object or fluid. These methods and apparatus sense a corresponding variation in an electric property of that gap and determine the latter force, magnetic fields, or wave or radiant energy in response to that corresponding variation, and thereby sense or measure such parameters as acceleration, position, particle mass, velocity, magnetic field strength, presence or direction, or wave or radiant energy intensity, presence or direction.

Implementation of a robotic flexible assembly system

NASA Technical Reports Server (NTRS)

Benton, Ronald C.

1987-01-01

As part of the Intelligent Task Automation program, a team developed enabling technologies for programmable, sensory controlled manipulation in unstructured environments. These technologies include 2-D/3-D vision sensing and understanding, force sensing and high speed force control, 2.5-D vision alignment and control, and multiple processor architectures. The subsequent design of a flexible, programmable, sensor controlled robotic assembly system for small electromechanical devices is described using these technologies and ongoing implementation and integration efforts. Using vision, the system picks parts dumped randomly in a tray. Using vision and force control, it performs high speed part mating, in-process monitoring/verification of expected results and autonomous recovery from some errors. It is programmed off line with semiautomatic action planning.

Iterative matrix algorithm for high precision temperature and force decoupling in multi-parameter FBG sensing.

PubMed

Hopf, Barbara; Dutz, Franz J; Bosselmann, Thomas; Willsch, Michael; Koch, Alexander W; Roths, Johannes

2018-04-30

A new iterative matrix algorithm has been applied to improve the precision of temperature and force decoupling in multi-parameter FBG sensing. For the first time, this evaluation technique allows the integration of nonlinearities in the sensor's temperature characteristic and the temperature dependence of the sensor's force sensitivity. Applied to a sensor cable consisting of two FBGs in fibers with 80 µm and 125 µm cladding diameter installed in a 7 m-long coiled PEEK capillary, this technique significantly reduced the uncertainties in friction-compensated temperature measurements. In the presence of high friction-induced forces of up to 1.6 N the uncertainties in temperature evaluation were reduced from several degrees Celsius if using a standard linear matrix approach to less than 0.5°C if using the iterative matrix approach in an extended temperature range between -35°C and 125°C.

Cell and molecular mechanics of biological materials

NASA Astrophysics Data System (ADS)

Bao, G.; Suresh, S.

2003-11-01

Living cells can sense mechanical forces and convert them into biological responses. Similarly, biological and biochemical signals are known to influence the abilities of cells to sense, generate and bear mechanical forces. Studies into the mechanics of single cells, subcellular components and biological molecules have rapidly evolved during the past decade with significant implications for biotechnology and human health. This progress has been facilitated by new capabilities for measuring forces and displacements with piconewton and nanometre resolutions, respectively, and by improvements in bio-imaging. Details of mechanical, chemical and biological interactions in cells remain elusive. However, the mechanical deformation of proteins and nucleic acids may provide key insights for understanding the changes in cellular structure, response and function under force, and offer new opportunities for the diagnosis and treatment of disease. This review discusses some basic features of the deformation of single cells and biomolecules, and examines opportunities for further research.

A resonant force sensor based on ionic polymer metal composites

NASA Astrophysics Data System (ADS)

Bonomo, Claudia; Fortuna, Luigi; Giannone, Pietro; Graziani, Salvatore; Strazzeri, Salvatore

2008-02-01

In this paper a novel force sensor, based on ionic polymer metal composites (IPMCs), is presented. The system has DC sensing capabilities and is able to work in the range of a few millinewtons. IPMCs are emerging materials used to realize motion actuators and sensors. An IPMC strip is activated in a beam fixed/simply-supported configuration. The beam is tightened at the simply-supported end by a force. This influences the natural resonant frequency of the beam; the value of the resonant frequency is used in the proposed system to estimate the force applied in the axial direction. The performance of the system based on the IPMC material has proved to be comparable with that of sensors based on other sensing mechanisms. This suggests the possibility of using this class of polymeric devices to realize PMEMS (plastic micro electrical mechanical systems) sensors.

Remote sensing: Physical principles, sensors and products, and the LANDSAT

NASA Technical Reports Server (NTRS)

Dejesusparada, N. (Principal Investigator); Steffen, C. A.; Lorenzzetti, J. A.; Stech, J. L.; Desouza, R. C. M.

1981-01-01

Techniques of data acquisition by remote sensing are introduced in this teaching aid. The properties of the elements involved (radiant energy, topograph, atmospheric attenuation, surfaces, and sensors) are covered. Radiometers, photography, scanners, and radar are described as well as their products. Aspects of the LANDSAT system examined include the characteristics of the satellite and its orbit, the multispectral band scanner, and the return beam vidicon. Pixels (picture elements), pattern registration, and the characteristics, reception, and processing of LANDSAT imagery are also considered.

A temperature control design for a tapered element oscillating microbalance sensing surface

NASA Technical Reports Server (NTRS)

1982-01-01

A design study is presented which shows that a tapered element oscillating microbalance can be adapted for temperature control under space application by mating with multistage thermoelectric coolers in such a way that an integral structure evolves. The control of the temperature of the sensing surface can be achieved in a number of ways. An indirect method which uses a measurement of the absorbed power is recommended. The design goals can be met if a relaxation of the power requirement can be considered.

Design and performance evaluation of a master controller for endovascular catheterization.

PubMed

Guo, Jin; Guo, Shuxiang; Tamiya, Takashi; Hirata, Hideyuki; Ishihara, Hidenori

2016-01-01

It is difficult to manipulate a flexible catheter to target a position within a patient's complicated and delicate vessels. However, few researchers focused on the controller designs with much consideration of the natural catheter manipulation skills obtained from manual catheterization. Also, the existing catheter motion measurement methods probably lead to the difficulties in designing the force feedback device. Additionally, the commercially available systems are too expensive which makes them cost prohibitive to most hospitals. This paper presents a simple and cost-effective master controller for endovascular catheterization that can allow the interventionalists to apply the conventional pull, push and twist of the catheter used in current practice. A catheter-sensing unit (used to measure the motion of the catheter) and a force feedback unit (used to provide a sense of resistance force) are both presented. A camera was used to allow a contactless measurement avoiding additional friction, and the force feedback in the axial direction was provided by the magnetic force generated between the permanent magnets and the powered coil. Performance evaluation of the controller was evaluated by first conducting comparison experiments to quantify the accuracy of the catheter-sensing unit, and then conducting several experiments to evaluate the force feedback unit. From the experimental results, the minimum and the maximum errors of translational displacement were 0.003 mm (0.01 %) and 0.425 mm (1.06 %), respectively. The average error was 0.113 mm (0.28 %). In terms of rotational angles, the minimum and the maximum errors were 0.39°(0.33 %) and 7.2°(6 %), respectively. The average error was 3.61°(3.01 %). The force resolution was approximately 25 mN and a maximum current of 3A generated an approximately 1.5 N force. Based on analysis of requirements and state-of-the-art computer-assisted and robot-assisted training systems for endovascular catheterization, a new master controller with force feedback interface was proposed to maintain the natural endovascular catheterization skills of the interventionalists.

Optical Indoor Positioning System Based on TFT Technology.

PubMed

Gőzse, István

2015-12-24

A novel indoor positioning system is presented in the paper. Similarly to the camera-based solutions, it is based on visual detection, but it conceptually differs from the classical approaches. First, the objects are marked by LEDs, and second, a special sensing unit is applied, instead of a camera, to track the motion of the markers. This sensing unit realizes a modified pinhole camera model, where the light-sensing area is fixed and consists of a small number of sensing elements (photodiodes), and it is the hole that can be moved. The markers are tracked by controlling the motion of the hole, such that the light of the LEDs always hits the photodiodes. The proposed concept has several advantages: Apart from its low computational demands, it is insensitive to the disturbing ambient light. Moreover, as every component of the system can be realized by simple and inexpensive elements, the overall cost of the system can be kept low.

Switching sliding mode force tracking control of piezoelectric-hydraulic pump-based friction element actuation systems for automotive transmissions

NASA Astrophysics Data System (ADS)

Kim, Gi-Woo; Wang, K. W.

2009-08-01

In this study, a nonlinear sliding-mode controller is designed for force tracking of a piezoelectric-hydraulic pump (PHP)-based actuation system, which is developed to replace the current electro-hydraulic actuation systems for automatic transmission (AT) friction elements, such as band brakes or clutches. By utilizing the PHP, one can eliminate the various hydraulic components (oil pump, regulating valve and control valve) in current ATs and achieve a simpler configuration with more efficient operation. With the derived governing equation of motion of the PHP-based actuation system integrated with the friction element (band brake), a switching control law is synthesized based on the sliding-mode theory. To evaluate the effectiveness of the proposed control law, its force tracking performance for the engagement of a friction element during an AT 1\\to 2 up-shift is examined experimentally. It is shown that one can successfully track the desired force trajectory for AT shift control with small tracking error. This study demonstrates the potential of the PHP as a new controllable actuation system for AT friction elements.

Setting up virgin stress conditions in discrete element models.

PubMed

Rojek, J; Karlis, G F; Malinowski, L J; Beer, G

2013-03-01

In the present work, a methodology for setting up virgin stress conditions in discrete element models is proposed. The developed algorithm is applicable to discrete or coupled discrete/continuum modeling of underground excavation employing the discrete element method (DEM). Since the DEM works with contact forces rather than stresses there is a need for the conversion of pre-excavation stresses to contact forces for the DEM model. Different possibilities of setting up virgin stress conditions in the DEM model are reviewed and critically assessed. Finally, a new method to obtain a discrete element model with contact forces equivalent to given macroscopic virgin stresses is proposed. The test examples presented show that good results may be obtained regardless of the shape of the DEM domain.

Setting up virgin stress conditions in discrete element models

PubMed Central

Rojek, J.; Karlis, G.F.; Malinowski, L.J.; Beer, G.

2013-01-01

In the present work, a methodology for setting up virgin stress conditions in discrete element models is proposed. The developed algorithm is applicable to discrete or coupled discrete/continuum modeling of underground excavation employing the discrete element method (DEM). Since the DEM works with contact forces rather than stresses there is a need for the conversion of pre-excavation stresses to contact forces for the DEM model. Different possibilities of setting up virgin stress conditions in the DEM model are reviewed and critically assessed. Finally, a new method to obtain a discrete element model with contact forces equivalent to given macroscopic virgin stresses is proposed. The test examples presented show that good results may be obtained regardless of the shape of the DEM domain. PMID:27087731

Parametric investigation of scalable tactile sensors

NASA Astrophysics Data System (ADS)

Saadatzi, Mohammad Nasser; Yang, Zhong; Baptist, Joshua R.; Sahasrabuddhe, Ritvij R.; Wijayasinghe, Indika B.; Popa, Dan O.

2017-05-01

In the near future, robots and humans will share the same environment and perform tasks cooperatively. For intuitive, safe, and reliable physical human-robot interaction (pHRI), sensorized robot skins for tactile measurements of contact are necessary. In a previous study, we presented skins consisting of strain gauge arrays encased in silicone encapsulants. Although these structures could measure normal forces applied directly onto the sensing elements, they also exhibited blind spots and response asymmetry to certain loading patterns. This study presents a parametric investigation of piezoresistive polymeric strain gauge that exhibits a symmetric omniaxial response thanks to its novel star-shaped structure. This strain gauge relies on the use of gold micro-patterned star-shaped structures with a thin layer of PEDOT:PSS which is a flexible polymer with piezoresistive properties. In this paper, the sensor is first modeled and comprehensively analyzed in the finite-element simulation environment COMSOL. Simulations include stress-strain loading for a variety of structure parameters such as gauge lengths, widths, and spacing, as well as multiple load locations relative to the gauge. Subsequently, sensors with optimized configurations obtained through simulations were fabricated using cleanroom photolithographic and spin-coating processes, and then experimentally tested. Results show a trend-wise agreement between experiments and simulations.

Passivity-based control with collision avoidance for a hub-beam spacecraft

NASA Astrophysics Data System (ADS)

Wen, Hao; Chen, Ti; Jin, Dongping; Hu, Haiyan

2017-01-01

For the application of robotically assembling large space structures, a feedback control law is synthesized for transitional and rotational maneuvers of a 'tug' spacecraft in order to transport a flexible element to a desired position without colliding with other space bodies. The flexible element is treated as a long beam clamped to the 'tug' spacecraft modelled as a rigid hub. First, the physical property of passivity of Euler-Lagrange system is exploited to design the position and attitude controllers by taking a simpler obstacle-free control problem into account. To reduce sensing and actuating requirements, the vibration modes of the beam appendage are supposed to be not directly measured and actuated on. Besides, the requirements of measuring velocities are removed with the aid of a dynamic extension technique. Second, the bounding boxes in the form of super-quadric surfaces are exploited to enclose the maximal extents of the obstacles and the hub-beam spacecraft. The collision avoidance between bounding boxes is achieved by applying additional repulsive force and torque to the spacecraft based on the method of artificial potential field. Finally, the effectiveness of proposed control scheme is numerically demonstrated via case studies.

Plant nodulation inducers enhance horizontal gene transfer of Azorhizobium caulinodans symbiosis island

PubMed Central

Ling, Jun; Wang, Hui; Wu, Ping; Li, Tao; Tang, Yu; Naseer, Nawar; Zheng, Huiming; Masson-Boivin, Catherine; Zhong, Zengtao

2016-01-01

Horizontal gene transfer (HGT) of genomic islands is a driving force of bacterial evolution. Many pathogens and symbionts use this mechanism to spread mobile genetic elements that carry genes important for interaction with their eukaryotic hosts. However, the role of the host in this process remains unclear. Here, we show that plant compounds inducing the nodulation process in the rhizobium-legume mutualistic symbiosis also enhance the transfer of symbiosis islands. We demonstrate that the symbiosis island of the Sesbania rostrata symbiont, Azorhizobium caulinodans, is an 87.6-kb integrative and conjugative element (ICEAc) that is able to excise, form a circular DNA, and conjugatively transfer to a specific site of gly-tRNA gene of other rhizobial genera, expanding their host range. The HGT frequency was significantly increased in the rhizosphere. An ICEAc-located LysR-family transcriptional regulatory protein AhaR triggered the HGT process in response to plant flavonoids that induce the expression of nodulation genes through another LysR-type protein, NodD. Our study suggests that rhizobia may sense rhizosphere environments and transfer their symbiosis gene contents to other genera of rhizobia, thereby broadening rhizobial host-range specificity. PMID:27849579

Plant nodulation inducers enhance horizontal gene transfer of Azorhizobium caulinodans symbiosis island.

PubMed

Ling, Jun; Wang, Hui; Wu, Ping; Li, Tao; Tang, Yu; Naseer, Nawar; Zheng, Huiming; Masson-Boivin, Catherine; Zhong, Zengtao; Zhu, Jun

2016-11-29

Horizontal gene transfer (HGT) of genomic islands is a driving force of bacterial evolution. Many pathogens and symbionts use this mechanism to spread mobile genetic elements that carry genes important for interaction with their eukaryotic hosts. However, the role of the host in this process remains unclear. Here, we show that plant compounds inducing the nodulation process in the rhizobium-legume mutualistic symbiosis also enhance the transfer of symbiosis islands. We demonstrate that the symbiosis island of the Sesbania rostrata symbiont, Azorhizobium caulinodans, is an 87.6-kb integrative and conjugative element (ICE Ac ) that is able to excise, form a circular DNA, and conjugatively transfer to a specific site of gly-tRNA gene of other rhizobial genera, expanding their host range. The HGT frequency was significantly increased in the rhizosphere. An ICE Ac -located LysR-family transcriptional regulatory protein AhaR triggered the HGT process in response to plant flavonoids that induce the expression of nodulation genes through another LysR-type protein, NodD. Our study suggests that rhizobia may sense rhizosphere environments and transfer their symbiosis gene contents to other genera of rhizobia, thereby broadening rhizobial host-range specificity.

A Passive and Wireless Sensor for Bone Plate Strain Monitoring.

PubMed

Tan, Yisong; Hu, Jiale; Ren, Limin; Zhu, Jianhua; Yang, Jiaqi; Liu, Di

2017-11-16

This paper reports on a sensor for monitoring bone plate strain in real time. The detected bone plate strain could be used for judging the healing state of fractures in patients. The sensor consists of a magnetoelastic material, which can be wirelessly connected and passively embedded. In order to verify the effectiveness of the sensor, a tibia-bone plate-screw (TBS) model was established using the finite element analysis method. A variation of the bone plate strain was obtained via this model. A goat hindquarter tibia was selected as the bone fracture model in the experiment. The tibia was fixed on a high precision load platform and an external force was applied. Bone plate strain variation during the bone fracture healing process was acquired with sensing coils. Simulation results indicated that bone plate strain decreases as the bone gradually heals, which is consistent with the finite element analysis results. This validated the soundness of the sensor reported here. This sensor has wireless connections, no in vivo battery requirement, and long-term embedding. These results can be used not only for clinical practices of bone fracture healing, but also for bone fracture treatment and rehabilitation equipment design.

Resistive Exercise Device

NASA Technical Reports Server (NTRS)

Smith, Damon C. (Inventor)

2005-01-01

An exercise device 10 is particularly well suited for use in low gravity environments, and includes a frame 12 with plurality of resistance elements 30,82 supported in parallel on the frame. A load transfer member 20 is moveable relative to the frame for transferring the applied force to the free end of each captured resistance element. Load selection template 14 is removably secured both to the load transfer member, and a plurality of capture mechanisms engage the free end of corresponding resistance elements. The force applying mechanism 53 may be a handle, harness or other user interface for applying a force to move the load transfer member.

Design of a phased array for the generation of adaptive radiation force along a path surrounding a breast lesion for dynamic ultrasound elastography imaging.

PubMed

Ekeom, Didace; Hadj Henni, Anis; Cloutier, Guy

2013-03-01

This work demonstrates, with numerical simulations, the potential of an octagonal probe for the generation of radiation forces in a set of points following a path surrounding a breast lesion in the context of dynamic ultrasound elastography imaging. Because of the in-going wave adaptive focusing strategy, the proposed method is adapted to induce shear wave fronts to interact optimally with complex lesions. Transducer elements were based on 1-3 piezocomposite material. Three-dimensional simulations combining the finite element method and boundary element method with periodic boundary conditions in the elevation direction were used to predict acoustic wave radiation in a targeted region of interest. The coupling factor of the piezocomposite material and the radiated power of the transducer were optimized. The transducer's electrical impedance was targeted to 50 Ω. The probe was simulated by assembling the designed transducer elements to build an octagonal phased-array with 256 elements on each edge (for a total of 2048 elements). The central frequency is 4.54 MHz; simulated transducer elements are able to deliver enough power and can generate the radiation force with a relatively low level of voltage excitation. Using dynamic transmitter beamforming techniques, the radiation force along a path and resulting acoustic pattern in the breast were simulated assuming a linear isotropic medium. Magnitude and orientation of the acoustic intensity (radiation force) at any point of a generation path could be controlled for the case of an example representing a heterogeneous medium with an embedded soft mechanical inclusion.

The strategy for improving water-quality monitoring in the United States; final report of the Intergovernmental Task Force on Monitoring Water Quality; technical appendices

USGS Publications Warehouse

,

1995-01-01

The Intergovernmental Task Force on Monitoring Water Quality (ITFM) prepared this report in collaboration with representatives of all levels of government and the private sector. The report recommends a strategy for nationwide water-quality monitoring and technical monitoring improvements to support sound water-quality decisionmaking. The strategy is intended to achieve a better return on public and private investments in monitoring, environmental protection, and natural resources management. It is also designed to expand the base of information useful to a variety of users at multiple geographic scales. Institutional and technical changes are needed to improve water-quality monitoring and to meet the full range of monitoring requirements. Monitoring must be incorporated as a critical element of program planning, implementation, and evaluation. The strategy includes recommendations in many key elements, such as the development of goal-oriented monitoring and indicators, institutional collaboration, and methods comparability. Initial actions have been taken to implement the strategy. Several Federal agencies have jointly purchased and shared remotely sensed land-cover information needed for water assessment. Major agency data systems are using common data-element names and reference tables that will ensure easy sharing of data. A number of States have held meetings with collectors of water information to initiate statewide monitoring strategies. New monitoring guidance has been developed for Federal water-quality grants to States. Many State offices have changed monitoring programs to place emphasis on priority watersheds and to improve assessment of water quality. As the competition increases for adequate supplies of clean water, concerns about public health and the environment escalate, and more demands are placed on the water information infrastructure. To meet these demands, the collaborative approach has already produced benefits, which will continue to grow as the recommendations are implemented

Practical Considerations for Using Constant Force Springs in Space-Based Mechanisms

NASA Technical Reports Server (NTRS)

Williams, R. Brett; Fisher, Charles D.; Gallon, John C.

2013-01-01

Mechanical springs are a common element in mechanism from all walks of life; cars, watches, appliances, and many others. These springs generally exhibit a linear relationship between force and deflection. In small mechanisms, deflections are small so the variation in spring force between one position and another are generally small and do not influence the design or functionality of the device. However, as the spacecraft industry drives towards larger, deployable satellites, the distances a spring or springs must function over can become considerable so much so that the structural integrity of the device may be impacted. As such, an increasingly common mechanism element is the constant force spring- one that provides a constant force regardless of deflection. These elements are commonly in the conceptual design phase to deal with system-level large deflections, but in the detailed design or integration test phase they can pose significant implementation issues. This article addresses some of the detailed issues in order for these constant force springs to be properly designed into space systems.

Component mode synthesis and large deflection vibration of complex structures. Volume 3: Multiple-mode nonlinear free and forced vibrations of beams using finite element method

NASA Technical Reports Server (NTRS)

Mei, Chuh; Shen, Mo-How

1987-01-01

Multiple-mode nonlinear forced vibration of a beam was analyzed by the finite element method. Inplane (longitudinal) displacement and inertia (IDI) are considered in the formulation. By combining the finite element method and nonlinear theory, more realistic models of structural response are obtained more easily and faster.

Predictions of the electro-mechanical response of conductive CNT-polymer composites

NASA Astrophysics Data System (ADS)

Matos, Miguel A. S.; Tagarielli, Vito L.; Baiz-Villafranca, Pedro M.; Pinho, Silvestre T.

2018-05-01

We present finite element simulations to predict the conductivity, elastic response and strain-sensing capability of conductive composites comprising a polymeric matrix and carbon nanotubes. Realistic representative volume elements (RVE) of the microstructure are generated and both constituents are modelled as linear elastic solids, with resistivity independent of strain; the electrical contact between nanotubes is represented by a new element which accounts for quantum tunnelling effects and captures the sensitivity of conductivity to separation. Monte Carlo simulations are conducted and the sensitivity of the predictions to RVE size is explored. Predictions of modulus and conductivity are found in good agreement with published results. The strain-sensing capability of the material is explored for multiaxial strain states.

Experimental Nonlinear Dynamics and Snap-Through of Post-Buckled Thin Laminated Composite Plates

NASA Astrophysics Data System (ADS)

Kim, Han-Gyu

Modern aerospace systems are increasingly being designed with composite panels and plates to achieve light weight and high specific strength and stiffness. For constrained panels, thermally-induced axial loading may cause buckling of the structure, which can lead to nonlinear and potentially chaotic behavior. When post-buckled composite plates experience snap-through, they are subjected to large-amplitude deformations and in-plane compressive loading. These phenomena pose a potential threat to the structural integrity of composite structures. In this work, the nonlinear dynamic behavior of post-buckled composite plates was investigated experimentally and computationally. For the experimental work, an electrodynamic shaker was used to apply harmonic loads and the dynamic response of plate specimens was measured using a single-point displacement-sensing laser, a double-point laser vibrometer (velocity-sensing), and a set of digital image correlation cameras. Both chaotic and periodic steady-state snap-through behaviors were investigated. The experimental data were used to characterize snap-through behaviors of the post-buckled specimens and their boundaries in the harmonic forcing parameter space. The nonlinear behavior of post-buckled plates was modeled using the classical laminated plate theory (CLPT) and the von Karman strain-displacement relations. The static equilibrium paths of the post-buckled plates were analyzed using an arc-length method with a branch-switching technique. For the dynamic analysis, the nonlinear equations of motion were derived based on CLPT and the nonlinear finite element model of the equations was constructed using the Hermite cubic interpolation functions for both conforming and nonconforming elements. The numerical analyses were conducted using the model and were compared with the experimental data.

Photonic all-silicon microsensor for electromagnetic power in the microwave and millimeter-wave range

NASA Astrophysics Data System (ADS)

Rendina, Ivo; Bellucci, Marco; Cocorullo, Giuseppe; Della Corte, Francesco G.; Iodice, Mario

2000-03-01

A new type of non-perturbing electromagnetic power sensor for microwaves and millimeter-waves, based on the thermo- optical effect in a silicon interferometric etalon cavity is presented. The incident field power is partially dissipated into the all-silicon metal-less etalon, constituting the sensing element of the detector, so causing its temperature increase. This, in turn, induces the intensity modulation of a probe laser beam reflected by the cavity after a multiple beam interference process. The sensing element is directly connected to an optical fiber for remote interrogation, so avoiding the use of perturbing coaxial cables. The performances of such a new class of non-perturbing and wideband probes, in terms of sensitivity and resolution are discussed in detail. The experimental results concerning the characterization of a preliminary prototype sensor are presented and compared with theoretical data. The dependence of the sensor response on the electromagnetic frequency and on the sensing element characteristics is finally discussed.

Modified sensing element of a fibre-optic current sensor based on a low-eigenellipticity spun fibre

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

Przhiyalkovsky, Ya V; Morshnev, S K; Starostin, N I

2014-10-31

We have proposed and investigated a modified sensing element of a spun fibre current sensor for the case when the beat length of the built-in linear birefringence of the fibre is equal to or less than the spin pitch of its helical structure. The proposed configuration makes it possible to restore the interferometer contrast reduced because of the decrease in the ellipticity of the wavelength-averaged polarisation state of radiation propagating in such spun fibre. The modified sensing element contains two polarisation state converters: one, located at the spun fibre input, produces polarisation with ellipticity equal to the eigenellipticity of themore » fibre, and the other ensures conversion of the elliptical polarisation to an orthogonal one through mirror reflection at the fibre output. We have also demonstrated that the magneto-optical sensitivity decreases slightly for the analysed spectrum-averaged parameters of the polarisation state of radiation in the spun fibre. Experimental data lend support to the theoretical predictions. (fibre-optic sensors)« less

Magnetic elements for switching magnetization magnetic force microscopy tips.

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

Cambel, V.; Elias, P.; Gregusova, D.

2010-09-01

Using combination of micromagnetic calculations and magnetic force microscopy (MFM) imaging we find optimal parameters for novel magnetic tips suitable for switching magnetization MFM. Switching magnetization MFM is based on two-pass scanning atomic force microscopy with reversed tip magnetization between the scans. Within the technique the sum of the scanned data with reversed tip magnetization depicts local atomic forces, while their difference maps the local magnetic forces. Here we propose the design and calculate the magnetic properties of tips suitable for this scanning probe technique. We find that for best performance the spin-polarized tips must exhibit low magnetic moment, lowmore » switching fields, and single-domain state at remanence. The switching field of such tips is calculated and optimum shape of the Permalloy elements for the tips is found. We show excellent correspondence between calculated and experimental results for Py elements.« less

Locomotive and reptation motion induced by internal force and friction.

PubMed

Sakaguchi, Hidetsugu; Ishihara, Taisuke

2011-06-01

We propose a simple mechanical model of locomotion induced by internal force and friction. We first construct a system of two elements as an analog of the bipedal motion. The internal force does not induce a directional motion by itself because of the action-reaction law, but a directional motion becomes possible by the control of the frictional force. The efficiency of these model systems is studied using an analogy to the heat engine. As a modified version of the two-element model, we construct a model that exhibits a bipedal motion similar to kinesin's motion of molecular motor. Next, we propose a linear chain model and a ladder model as an extension of the original two-element model. We find a transition from a straight to a snake-like motion in a ladder model by changing the strength of the internal force.

Multiple-mode nonlinear free and forced vibrations of beams using finite element method

NASA Technical Reports Server (NTRS)

Mei, Chuh; Decha-Umphai, Kamolphan

1987-01-01

Multiple-mode nonlinear free and forced vibration of a beam is analyzed by the finite element method. The geometric nonlinearity is investigated. Inplane displacement and inertia (IDI) are also considered in the formulation. Harmonic force matrix is derived and explained. Nonlinear free vibration can be simply treated as a special case of the general forced vibration by setting the harmonic force matrix equal to zero. The effect of the higher modes is more pronouced for the clamped supported beam than the simply supported one. Beams without IDI yield more effect of the higher modes than the one with IDI. The effects of IDI are to reduce nonlinearity. For beams with end supports restrained from axial movement (immovable cases), only the hardening type nonlinearity is observed. However, beams of small slenderness ratio (L/R = 20) with movable end supports, the softening type nonlinearity is found. The concentrated force case yields a more severe response than the uniformly distributed force case. Finite element results are in good agreement with the solution of simple elliptic response, harmonic balance method, and Runge-Kutte method and experiment.

Optical fiber magnetic field sensors with TbDyFe magnetostrictive thin films as sensing materials.

PubMed

Yang, Minghong; Dai, Jixiang; Zhou, Ciming; Jiang, Desheng

2009-11-09

Different from usually-used bulk magnetostrictive materials, magnetostrictive TbDyFe thin films were firstly proposed as sensing materials for fiber-optic magnetic field sensing characterization. By magnetron sputtering process, TbDyFe thin films were deposited on etched side circle of a fiber Bragg Grating (FBG) as sensing element. There exists more than 45pm change of FBG wavelength when magnet field increase up to 50 mT. The response to magnetic field is reversible, and could be applicable for magnetic and current sensing.

Active control of sound transmission through a rectangular panel using point-force actuators and piezoelectric film sensors.

PubMed

Sanada, Akira; Higashiyama, Kouji; Tanaka, Nobuo

2015-01-01

This study deals with the active control of sound transmission through a rectangular panel, based on single input, single output feedforward vibration control using point-force actuators and piezoelectric film sensors. It focuses on the phenomenon in which the sound power transmitted through a finite-sized panel drops significantly at some frequencies just below the resonance frequencies of the panel in the low-frequency range as a result of modal coupling cancellation. In a previous study, it was shown that when point-force actuators are located on nodal lines for the frequency at which this phenomenon occurs, a force equivalent to the incident sound wave can act on the panel. In this study, a practical method for sensing volume velocity using a small number of piezoelectric film strips is investigated. It is found that two quadratically shaped piezoelectric film strips, attached at the same nodal lines as those where the actuators were placed, can sense the volume velocity approximately in the low-frequency range. Results of simulations show that combining the proposed actuation method and the sensing method can achieve a practical control effect at low frequencies over a wide frequency range. Finally, experiments are carried out to demonstrate the validity and feasibility of the proposed method.

Probing Gravitational Sensitivity in Biological Systems Using Magnetic Body Forces

NASA Technical Reports Server (NTRS)

Guevorkian, Karine; Wurzel, Sam; Mihalusova, Mariana; Valles, Jim

2003-01-01

At Brown University, we are developing the use of magnetic body forces as a means to simulate variable gravity body forces on biological systems. This tool promises new means to probe gravi-sensing and the gravi-response of biological systems. It also has the potential as a technique for screening future systems for space flight experiments.

Applications of Microbial Cell Sensors

NASA Astrophysics Data System (ADS)

Shimomura-Shimizu, Mifumi; Karube, Isao

Since the first microbial cell sensor was studied by Karube et al. in 1977, many types of microbial cell sensors have been developed as analytical tools. The microbial cell sensor utilizes microbes as a sensing element and a transducer. The characteristics of microbial cell sensors as sensing devices are a complete contrast to those of enzyme sensors or immunosensors, which are highly specific for the substrates of interest, although the specificity of the microbial cell sensor has been improved by genetic modification of the microbe used as the sensing element. Microbial cell sensors have the advantages of tolerance to measuring conditions, a long lifetime, and good cost performance, and have the disadvantage of a long response time. In this review, applications of microbial cell sensors are summarized.

LWIR Microgrid Polarimeter for Remote Sensing Studies

DTIC Science & Technology

2010-02-28

Polarimeter for Remote Sensing Studies 5b. GRANT NUMBER FA9550-08-1-0295 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 1. Scott Tyo 5e. TASK...and tested at the University of Arizona, and preliminary images are shown in this final report. 15. SUBJECT TERMS Remote Sensing , polarimetry 16...7.0 LWIR Microgrid Polarimeter for Remote Sensing Studies J. Scott Tyo College of Optical Sciences University of Arizona Tucson, AZ, 85721 tyo

Radioactive ion detector

DOEpatents

Bower, Kenneth E.; Weeks, Donald R.

1997-01-01

Apparatus for detecting the presence, in aqueous media, of substances which emit alpha and/or beta radiation and determining the oxidation state of these radioactive substances, that is, whether they are in cationic or anionic form. In one embodiment, a sensor assembly has two elements, one comprised of an ion-exchange material which binds cations and the other comprised of an ion-exchange material which binds anions. Each ion-exchange element is further comprised of a scintillation plastic and a photocurrent generator. When a radioactive substance to which the sensor is exposed binds to either element and emits alpha or beta particles, photons produced in the scintillation plastic illuminate the photocurrent generator of that element. Sensing apparatus senses generator output and thereby indicates whether cationic species or anionic species or both are present and also provides an indication of species quantity.

Radioactive ion detector

DOEpatents

Bower, K.E.; Weeks, D.R.

1997-08-12

Apparatus for detecting the presence, in aqueous media, of substances which emit alpha and/or beta radiation and determining the oxidation state of these radioactive substances, that is, whether they are in cationic or anionic form. In one embodiment, a sensor assembly has two elements, one comprised of an ion-exchange material which binds cations and the other comprised of an ion-exchange material which binds anions. Each ion-exchange element is further comprised of a scintillation plastic and a photocurrent generator. When a radioactive substance to which the sensor is exposed binds to either element and emits alpha or beta particles, photons produced in the scintillation plastic illuminate the photocurrent generator of that element. Sensing apparatus senses generator output and thereby indicates whether cationic species or anionic species or both are present and also provides an indication of species quantity. 2 figs.

40 CFR 1045.801 - What definitions apply to this part?

Code of Federal Regulations, 2013 CFR

2013-07-01

... means any device, system, or element of design that someone can adjust (including those which are... emission control device means any element of design that senses temperature, motive speed, engine RPM... on a continuous mixture of those fuels. Emission control system means any device, system, or element...

Auditory Force Feedback Substitution Improves Surgical Precision during Simulated Ophthalmic Surgery

PubMed Central

Cutler, Nathan; Balicki, Marcin; Finkelstein, Mark; Wang, Jiangxia; Gehlbach, Peter; McGready, John; Iordachita, Iulian; Taylor, Russell; Handa, James T.

2013-01-01

Purpose. To determine the extent that auditory force feedback (AFF) substitution improves performance during a simulated ophthalmic peeling procedure. Methods. A 25-gauge force-sensing microforceps was linked to two AFF modes. The “alarm” AFF mode sounded when the force reached 9 mN. The “warning” AFF mode made beeps with a frequency proportional to the generated force. Participants with different surgical experience levels were asked to peel a series of bandage strips off a platform as quickly as possible without exceeding 9 mN of force. In study arm A, participants peeled with alarm and warning AFF modes, the order randomized within the experience level. In study arm B, participants first peeled without AFF, then alarm or warning AFF (order randomized within the experience level), and finally without AFF. Results. Of the 28 “surgeon” participants, AFF improved membrane peeling performance, reducing average force generated (P < 0.01), SD of forces (P < 0.05), and force × time above 9 mN (P < 0.01). Short training periods with AFF improved subsequent peeling performance when AFF was turned off, with reductions in average force, SD of force, maximum force, time spent above 9 mN, and force × time above 9 mN (all P < 0.001). Except for maximum force, peeling with AFF reduced all force parameters (P < 0.05) more than peeling without AFF after completing a training session. Conclusions. AFF enables the surgeon to reduce the forces generated with improved precision during phantom membrane peeling, regardless of surgical experience. New force-sensing surgical tools combined with AFF offer the potential to enhance surgical training and improve surgical performance. PMID:23329663

Microelectromechanical systems contact stress sensor

DOEpatents

Kotovsky, Jack

2007-12-25

A microelectromechanical systems stress sensor comprising a microelectromechanical systems silicon body. A recess is formed in the silicon body. A silicon element extends into the recess. The silicon element has limited freedom of movement within the recess. An electrical circuit in the silicon element includes a piezoresistor material that allows for sensing changes in resistance that is proportional to bending of the silicon element.

Graviperception and gravitaxis in flagellates

NASA Astrophysics Data System (ADS)

Häder, D.; Ntefidou, M.

Many photosynthetic and heterotrophic flagellates perceive and respond to the gravitational vector of the Earth. Some previous hypotheses have suggested that the orientation is brought about by a passive physical mechanism such as buoyancy or hydrodynamic alignment. However, recent results have confirmed that e.g. the photosynthetic Euglena utilizes an active physiological sensor and an internal sensory transduction chain. This unicellular organism senses gravity by the sedimentation of its cellular content, which is heavier than the surrounding medium, onto the lower membrane. This force is believed to activate mechano-sensitive ion channels located at the front end under the trailing flagellum. The channels allow a gated influx of calcium which alters the internal electrical potential and may activate calmodulin. Further elements in the transduction chain are cyclic AMP and related enzymes. Recent flight experiments during parabolic aircraft maneuvers and on sounding rockets have confirmed previous terrestrial results and have provided detailed insight into the biochemical sensory transduction chain.

Smart Microsystems with Photonic Element and Their Applications to Aerospace Platforms

NASA Technical Reports Server (NTRS)

Adamovsky, G.; Lekki, J.; Sutter, J. K.; Sarkisov, S. S.; Curley, M. J.; Martin, C. E.

2000-01-01

The need to make manufacturing, operation, and support of airborne vehicles safer and more efficient forces engineers and scientists to look for lighter, cheaper, more reliable technologies. Light weight, immunity to EMI, fire safety, high bandwidth, and high signal fidelity have already made photonics in general and fiber optics in particular an extremely attractive medium for communication purposes. With the fiber optics serving as a central nervous system of the vehicle, generation, detection, and processing of the signal occurs at the peripherals that include smart structures and devices. Due to their interdisciplinary nature, photonic technologies cover such diverse areas as optical sensors and actuators, embedded and distributed sensors, sensing schemes and architectures, harnesses and connectors, signal processing and algorithms. The paper includes a brief description of work in the photonic area that is going on at NASA, especially at the Glenn Research Center (GRC).

Equifinality and its violations in a redundant system: multifinger accurate force production.

PubMed

Wilhelm, Luke; Zatsiorsky, Vladimir M; Latash, Mark L

2013-10-01

We explored a hypothesis that transient perturbations applied to a redundant system result in equifinality in the space of task-related performance variables but not in the space of elemental variables. The subjects pressed with four fingers and produced an accurate constant total force level. The "inverse piano" device was used to lift and lower one of the fingers smoothly. The subjects were instructed "not to intervene voluntarily" with possible force changes. Analysis was performed in spaces of finger forces and finger modes (hypothetical neural commands to fingers) as elemental variables. Lifting a finger led to an increase in its force and a decrease in the forces of the other three fingers; the total force increased. Lowering the finger back led to a drop in the force of the perturbed finger. At the final state, the sum of the variances of finger forces/modes computed across repetitive trials was significantly higher than the variance of the total force/mode. Most variance of the individual finger force/mode changes between the preperturbation and postperturbation states was compatible with constant total force. We conclude that a transient perturbation applied to a redundant system leads to relatively small variance in the task-related performance variable (equifinality), whereas in the space of elemental variables much more variance occurs that does not lead to total force changes. We interpret the results within a general theoretical scheme that incorporates the ideas of hierarchically organized control, control with referent configurations, synergic control, and the uncontrolled manifold hypothesis.

Parametric amplification in a resonant sensing array

NASA Astrophysics Data System (ADS)

Yie, Zi; Miller, Nicholas J.; Shaw, Steven W.; Turner, Kimberly L.

2012-03-01

We demonstrate parametric amplification of a multidegree of freedom resonant mass sensing array via an applied base motion containing the appropriate frequency content and phases. Applying parametric forcing in this manner is simple and aligns naturally with the vibrational properties of the sensing structure. Using this technique, we observe an increase in the quality factors of the coupled array resonances, which provides an effective means of improving device sensitivity.

A Simple Tiltmeter

NASA Technical Reports Server (NTRS)

Dix, M. G.; Harrison, D. R.; Edwards, T. M.

1982-01-01

Bubble vial with external aluminum-foil electrodes is sensing element for simple indicating tiltmeter. To measure bubble displacement, bridge circuit detects difference in capacitance between two sensing electrodes and reference electrode. Tiltmeter was developed for experiment on forecasting seismic events by changes in Earth's magnetic field.

Bolt clampup relaxation in a graphite/epoxy laminate

NASA Technical Reports Server (NTRS)

Shivakumar, K. N.; Crews, J. H., Jr.

1982-01-01

A simple bolted joint was analyzed to calculate bolt clampup relaxation for a graphite/epoxy (T300/5208) laminate. A viscoelastic finite element analysis of a double-lap joint with a steel bolt was conducted. Clampup forces were calculated for various steady-state temperature-moisture conditions using a 20-year exposure duration. The finite element analysis predicted that clampup forces relax even for the room-temperature-dry condition. The relaxations were 8, 13, 20, and 30 percent for exposure durations of 1 day, 1 month, 1 year, and 20 years, respectively. As expected, higher temperatures and moisture levels each increased the relaxation rate. The combined viscoelastic effects of steady-state temperature and moisture appeared to be additive. From the finite-element analysis, a simple equation was developed for clampup force relaxation. This generalized equation was used to calculate clampup forces for the same temperature-moisture conditions as used in the finite-element analysis. The two sets of calculated results agreed well.

How the Air Force Should Stay Engaged in Computer Vision Technology Development

DTIC Science & Technology

2007-04-01

present individuals. The survey 29 Paddy Comyn, "Sensing Forward to a Driverless Future," The Irish...34 Military Embedded Systems (2006). Comyn, Paddy. "Sensing Forward to a Driverless Future." The Irish Times 21 February 2007. Dakley, Norman C. The

Thomas Paine's "Common Sense": A Study in Polarity.

ERIC Educational Resources Information Center

Blair, Carole

Thomas Paine's "Common Sense," published in 1776, was a significant rhetorical event, having a polarizing effect on a situation marked by confusion and conflicting loyalties, in which prevailing views favored reconciliation of the American colonies with England. Paine's rhetoric intensified the conflict, forcing a cognitive restructuring…

An integrated, multi-sensing approach to describe the dynamic relations between turbulence, fluid-forces, and reconfiguration of a submerged plant model in steady flows.

NASA Astrophysics Data System (ADS)

Henry, Pierre-Yves; Aberle, Jochen; Dijkstra, Jasper; Myrhaug, Dag

2016-04-01

Aquatic vegetation plays a vital role in ecohydrological systems regulating many physical, chemical, and biological processes across a wide range of spatial and temporal scales. As a consequence, plant-flow interactions are of particular interest to a wide range of disciplines. While early studies of the interactions between vegetation and flowing water employed simplified and non-flexible structures such as rigid cylinders, recent studies have included flexible plants to identify the main characteristics of the hydrodynamics of vegetated flows. However, the description of plant reconfiguration has often been based on a static approach, i.e. considering the plant's deformation under a static load and neglecting turbulent fluctuations. Correlations between drag fluctuations, plant movements, and upstream turbulence were recently established showing that shear layer turbulence at the surface of the different plant elements (such as blades or stems) can contribute significantly to the dynamic behaviour of the plant. However, the relations between plant movement and force fluctuations might change under varying flow velocities, and although this point is crucial for mixing processes and plant dislodgement by fatigue, these aspects of fluid-structure interactions applied to aquatic vegetation remain largely unexplored. Using an innovative combination of sensing techniques in one set of experiments, this study investigates the relations between turbulence, fluctuating fluid forces and movements of a flexible cylindrical plant surrogate. A silicone-based flexible cylinder was attached at the bottom of a 1m wide flume in fully-developed uniform flow. The lower 22 cm of the plant surrogate were made of plain flexible silicone, while the higher 13cm included a casted rigid sensor, measuring accelerations at the tip of the surrogate. Forces were sampled at high frequencies at the surrogate's base by a 6-degrees-of-freedom force/torque sensor measuring down to the gram-force. Point measurements of turbulence were realized by two ADVs which were located upstream and downstream of the surrogate. Detailed motions of the surrogate were recorded by two cameras above and next to the flume. Image processing allowed for the characterization of the mean deformation and the different modes of horizontal and vertical 'vibration' of the surrogate. The experimental results were compared to numerical simulations obtained from an updated version of the Dynveg code developed by Deltares. The results showed a clear correlation between the cylinder's movements and the (drag) force fluctuations. Due to the swaying motion of the surrogate, the turbulence spectrum is significantly affected when the flow passes the plant model. The succession of several motion modes are observed as the velocity increases, affecting the dominant frequencies in the drag force spectrum and the overall drag. These preliminary results emphasise the importance of the dynamics of the plant flow interactions, and provide an example of the use of new methodologies to provide deeper insights into the physics of complex flows.

A Latin-cross-shaped integrated resonant cantilever with second torsion-mode resonance for ultra-resoluble bio-mass sensing

NASA Astrophysics Data System (ADS)

Xia, Xiaoyuan; Zhang, Zhixiang; Li, Xinxin

2008-03-01

Second torsion-mode resonance is proposed for microcantilever biosensors for ultra-high mass-weighing sensitivity and resolution. By increasing both the resonant frequency and Q-factor, the higher mode torsional resonance is favorable for improving the mass-sensing performance. For the first time, a Latin-cross-shaped second-mode resonant cantilever is constructed and optimally designed for both signal-readout and resonance-exciting elements. The cantilever sensor is fabricated by using silicon micromachining techniques. The transverse piezoresistive sensing element and the specific-shaped resonance-exciting loop are successfully integrated in the cantilever. Alpha-fetoprotein (AFP) antibody-antigen specific binding is implemented for the sensing experiment. The proposed cantilever sensor is designed with significantly superior sensitivity to the previously reported first torsion-mode one. After analysis with an Allan variance algorithm, which can be easily embedded in the sensing system, the Latin-cross-shaped second torsion-mode resonant cantilever is evaluated with ultra-high mass resolution. Therefore, the high-performance integrated micro-sensor is promising for on-the-spot bio-molecule detection.

Applications of Ko Displacement Theory to the Deformed Shape Predictions of the Doubly-Tapered Ikhana Wing

NASA Technical Reports Server (NTRS)

Ko, William L.; Richards, W. Lance; Fleischer, Van Tran

2009-01-01

The Ko displacement theory, formulated for weak nonuniform (slowly changing cross sections) cantilever beams, was applied to the deformed shape analysis of the doubly-tapered wings of the Ikhana unmanned aircraft. The two-line strain-sensing system (along the wingspan) was used for sensing the bending strains needed for the wing-deformed shapes (deflections and cross-sectional twist) analysis. The deflection equation for each strain-sensing line was expressed in terms of the bending strains evaluated at multiple numbers of strain-sensing stations equally spaced along the strain-sensing line. For the preflight shape analysis of the Ikhana wing, the strain data needed for input to the displacement equations for the shape analysis were obtained from the nodal-stress output of the finite-element analysis. The wing deflections and cross-sectional twist angles calculated from the displacement equations were then compared with those computed from the finite-element computer program. The Ko displacement theory formulated for weak nonlinear cantilever beams was found to be highly accurate in the deformed shape predictions of the doubly-tapered Ikhana wing.

Development of a two-dimensional skin friction balance nulling circuit using multivariable control theory

NASA Technical Reports Server (NTRS)

Tripp, John S.; Patek, Stephen D.

1988-01-01

Measurement of planar skin friction forces in aerodynamic testing currently requires installation of two perpendicularly mounted, single-axis balances; consequently, force components must be sensed at two distinct locations. A two-axis instrument developed at the Langley Research Center to overcome this disadvantage allows measurement of a two-dimensional force at one location. This paper describes a feedback-controlled nulling circuit developed for the NASA two-axis balance which, without external compensation, is inherently unstable because of its low friction mechanical design. Linear multivariable control theory is applied to an experimentally validated mathematical model of the balance to synthesize a state-variable feedback control law. Pole placement techniques and computer simulation studies are employed to select eigenvalues which provide ideal transient response with decoupled sensing dynamics.

Thermal Actuation Based 3-DoF Non-Resonant Microgyroscope Using MetalMUMPs

PubMed Central

Shakoor, Rana Iqtidar; Bazaz, Shafaat Ahmed; Kraft, Michael; Lai, Yongjun; Masood ul Hassan, Muhammad

2009-01-01

High force, large displacement and low voltage consumption are a primary concern for microgyroscopes. The chevron-shaped thermal actuators are unique in terms of high force generation combined with the large displacements at a low operating voltage in comparison with traditional electrostatic actuators. A Nickel based 3-DoF micromachined gyroscope comprising 2-DoF drive mode and 1-DoF sense mode oscillator utilizing the chevron-shaped thermal actuators is presented here. Analytical derivations and finite element simulations are carried out to predict the performance of the proposed device using the thermo-physical properties of electroplated nickel. The device sensitivity is improved by utilizing the dynamical amplification of the oscillation in 2-DoF drive mode using an active-passive mass configuration. A comprehensive theoretical description, dynamics and mechanical design considerations of the proposed gyroscopes model are discussed in detail. Parametric optimization of gyroscope, its prototype modeling and fabrication using MetalMUMPs has also been investigated. Dynamic transient simulation results predicted that the sense mass of the proposed device achieved a drive displacement of 4.1μm when a sinusoidal voltage of 0.5V is applied at 1.77 kHz exhibiting a mechanical sensitivity of 1.7μm /°/s in vacuum. The wide bandwidth frequency response of the 2-DoF drive mode oscillator consists of two resonant peaks and a flat region of 2.11 kHz between the peaks defining the operational frequency region. The sense mode resonant frequency can lie anywhere within this region and therefore the amplitude of the response is insensitive to structural parameter variations, enhancing device robustness against such variations. The proposed device has a size of 2.2 × 2.6 mm2, almost one third in comparison with existing M-DoF vibratory gyroscope with an estimated power consumption of 0.26 Watts. These predicted results illustrate that the chevron-shaped thermal actuator has a large voltage-stroke ratio shifting the paradigm in MEMS gyroscope design from the traditional interdigitated comb drive electrostatic actuator. These actuators have low damping compared to electrostatic comb drive actuators which may result in high quality factor microgyroscopes operating at atmospheric pressure. PMID:22574020

Structurally integrated organic light emitting device-based sensors for gas phase and dissolved oxygen.

PubMed

Shinar, Ruth; Zhou, Zhaoqun; Choudhury, Bhaskar; Shinar, Joseph

2006-05-24

A compact photoluminescence (PL)-based O2 sensor utilizing an organic light emitting device (OLED) as the light source is described. The sensor device is structurally integrated. That is, the sensing element and the light source, both typically thin films that are fabricated on separate glass substrates, are attached back-to-back. The sensing elements are based on the oxygen-sensitive dyes Pt- or Pd-octaethylporphyrin (PtOEP or PdOEP, respectively), which are embedded in a polystyrene (PS) matrix, or dissolved in solution. Their performance is compared to that of a sensing element based on tris(4,7-diphenyl-l,10-phenanthroline) Ru II (Ru(dpp)) embedded in a sol-gel film. A green OLED light source, based on tris(8-hydroxy quinoline Al (Alq3), was used to excite the porphyrin dyes; a blue OLED, based on 4,4'-bis(2,2'-diphenylviny1)-1,1'-biphenyl, was used to excite the Ru(dpp)-based sensing element. The O2 level was monitored in the gas phase and in water, ethanol, and toluene solutions by measuring changes in the PL lifetime tau of the O2-sensitive dyes. The sensor performance was evaluated in terms of the detection sensitivity, dynamic range, gas flow rate, and temperature effect, including the temperature dependence of tau in pure Ar and O2 atmospheres. The dependence of the sensitivity on the preparation procedure of the sensing film and on the PS and dye concentrations in the sensing element, whether a solid matrix or solution, were also evaluated. Typical values of the detection sensitivity in the gas phase, S(g) identical with tau(0% O2)/tau(100% O2), at 23 degrees C, were approximately 35 to approximately 50 for the [Alq3 OLED[/[PtOEP dye] pair; S(g) exceeded 200 for the Alq3/PdOEP sensor. For dissolved oxygen (DO) in water and ethanol, S(DO) (defined as the ratio of tau in de-oxygenated and oxygen-saturated solutions) was approximately 9.5 and approximately 11, respectively, using the PtOEP-based film sensor. The oxygen level in toluene was measured with PtOEP dissolved directly in the solution. That sensor exhibited a high sensitivity, but a limited dynamic range. Effects of aggregation of dye molecules, sensing film porosity, and the use of the OLED-based sensor arrays for O2 and multianalyte detection are also discussed.

Numerical Simulations for Distribution Characteristics of Internal Forces on Segments of Tunnel Linings

NASA Astrophysics Data System (ADS)

Li, Shouju; Shangguan, Zichang; Cao, Lijuan

A procedure based on FEM is proposed to simulate interaction between concrete segments of tunnel linings and soils. The beam element named as Beam 3 in ANSYS software was used to simulate segments. The ground loss induced from shield tunneling and segment installing processes is simulated in finite element analysis. The distributions of bending moment, axial force and shear force on segments were computed by FEM. The commutated internal forces on segments will be used to design reinforced bars on shield linings. Numerically simulated ground settlements agree with observed values.

Eddies and the Kuroshio between Luzon and Northeastern Taiwan: Integration of In Situ Observations and Remote Sensing Data

DTIC Science & Technology

2016-09-30

Taiwan: Integration of In Situ Observations and Remote Sensing Data Sb. GRANT NUMBER N00014-15-1-2593 Sc. PROGRAM ELEMENT NUMBER 1000000976 6... Remote Sensing Data Magdalena Andres Woods Hole Oceanographic Institution 1266 Woods Hole Road I Woods Hole, MA 02543 1. Long Term Goals The...MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM($) Dr. Theresa Paluszkiewicz ONR ONR Ocean Battlespace Sensing S& T Dept

Apparatus and Method for Generating Thrust Using a Two Dimensional, Asymmetrical Capacitor Module

NASA Technical Reports Server (NTRS)

Campbell, Jonathan W. (Inventor)

2001-01-01

A capacitor module system is provided for creating a thrust force. The system includes a capacitor module provided with a first conductive element having a cylindrical geometry. The first conductive element can be a hollow cylinder or a solid cylinder. The capacitor module also includes a second conductive element axially spaced from the first conductive element and of smaller axial extent. The second conductive element can be a flat disk, a dome, or a conductive tip at the end of a dielectric rod. A dielectric element is disposed between the first conductive element and the second conductive element. The system also includes a high voltage source having first and second terminals connected respectively to the first and second conductive elements. The high voltage source applies a high voltage to the conductive elements of sufficient value to create a thrust force on the module inducing movement thereof.

Convergence rates for finite element problems with singularities. Part 1: Antiplane shear. [crack

NASA Technical Reports Server (NTRS)

Plunkett, R.

1980-01-01

The problem of a finite crack in an infinite medium under antiplane shear load is considered. It is shown that the nodal forces at the tip of the crack accurately gives the order of singularity, that n energy release methods can give the strength to better than 1 percent with element size 1/10 the crack length, and that nodal forces give a much better estimate of the stress field than do the elements themselves. The finite element formulation and the factoring of tridiagonal matrices are discussed.

Fastener stretcher

NASA Technical Reports Server (NTRS)

Oconnor, J. W.; Orem, V. C. (Inventor)

1973-01-01

A description is given of a fastener stretcher used to apply a substantial pure axial tensile force to a structural bolt or similar fastening element. The system is comprised of a pair of telescoping elements, one of which is temporarily secured to the bolt. By spreading the telescoping elements axially, the bolt is tensioned axially to permit a nut or the like to be threaded with a minimum of torque; when the elements are then removed from the bolt, the axial forces on the bolt are taken up by the nut to retain the bolt in its stressed state.

On prediction and discovery of lunar ores

NASA Technical Reports Server (NTRS)

Haskin, Larry A.; Colson, Russell O.; Vaniman, David

1991-01-01

Sampling of lunar material and remote geochemical, mineralogical, and photogeologic sensing of the lunar surface, while meager, provide first-cut information about lunar composition and geochemical separation processes. Knowledge of elemental abundances in known lunar materials indicates which common lunar materials might serve as ores if there is economic demand and if economical extraction processes can be developed, remote sensing can be used to extend the understanding of the Moon's major geochemical separations and to locate potential ore bodies. Observed geochemical processes might lead to ores of less abundant elements under extreme local conditions.

Finite-element modeling of soft tissue rolling indentation.

PubMed

Sangpradit, Kiattisak; Liu, Hongbin; Dasgupta, Prokar; Althoefer, Kaspar; Seneviratne, Lakmal D

2011-12-01

We describe a finite-element (FE) model for simulating wheel-rolling tissue deformations using a rolling FE model (RFEM). A wheeled probe performing rolling tissue indentation has proven to be a promising approach for compensating for the loss of haptic and tactile feedback experienced during robotic-assisted minimally invasive surgery (H. Liu, D. P. Noonan, B. J. Challacombe, P. Dasgupta, L. D. Seneviratne, and K. Althoefer, "Rolling mechanical imaging for tissue abnormality localization during minimally invasive surgery, " IEEE Trans. Biomed. Eng., vol. 57, no. 2, pp. 404-414, Feb. 2010; K. Sangpradit, H. Liu, L. Seneviratne, and K. Althoefer, "Tissue identification using inverse finite element analysis of rolling indentation," in Proc. IEEE Int. Conf. Robot. Autom. , Kobe, Japan, 2009, pp. 1250-1255; H. Liu, D. Noonan, K. Althoefer, and L. Seneviratne, "The rolling approach for soft tissue modeling and mechanical imaging during robot-assisted minimally invasive surgery," in Proc. IEEE Int. Conf. Robot. Autom., May 2008, pp. 845-850; H. Liu, P. Puangmali, D. Zbyszewski, O. Elhage, P. Dasgupta, J. S. Dai, L. Seneviratne, and K. Althoefer, "An indentation depth-force sensing wheeled probe for abnormality identification during minimally invasive surgery," Proc. Inst. Mech. Eng., H, vol. 224, no. 6, pp. 751-63, 2010; D. Noonan, H. Liu, Y. Zweiri, K. Althoefer, and L. Seneviratne, "A dual-function wheeled probe for tissue viscoelastic property identification during minimally invasive surgery," in Proc. IEEE Int. Conf. Robot. Autom. , 2008, pp. 2629-2634; H. Liu, J. Li, Q. I. Poon, L. D. Seneviratne, and K. Althoefer, "Miniaturized force indentation-depth sensor for tissue abnormality identification," IEEE Int. Conf. Robot. Autom., May 2010, pp. 3654-3659). A sound understanding of wheel-tissue rolling interaction dynamics will facilitate the evaluation of signals from rolling indentation. In this paper, we model the dynamic interactions between a wheeled probe and a soft tissue sample using the ABAQUS FE software package. The aim of this work is to more precisely locate abnormalities within soft tissue organs using RFEM and hence aid surgeons to improve diagnostic ability. The soft tissue is modeled as a nonlinear hyperelastic material with geometrical nonlinearity. The proposed RFEM was validated on a silicone phantom and a porcine kidney sample. The results show that the proposed method can predict the wheel-tissue interaction forces of rolling indentation with good accuracy and can also accurately identify the location and depth of simulated tumors.

Net Force of an Ideal Conductor on an Element of a Line of Charge Moving With Extreme Relativistic Speed

ERIC Educational Resources Information Center

Cawley, Robert

1978-01-01

Considers the problem of determining the force on an element of a finite length line of charge moving horizontally with extreme relativistic speed through an evacuated space above an infinite plane ideal conducting surface. (SL)

The Spectrum Analysis Solution (SAS) System: Theoretical Analysis, Hardware Design and Implementation.

PubMed

Narayanan, Ram M; Pooler, Richard K; Martone, Anthony F; Gallagher, Kyle A; Sherbondy, Kelly D

2018-02-22

This paper describes a multichannel super-heterodyne signal analyzer, called the Spectrum Analysis Solution (SAS), which performs multi-purpose spectrum sensing to support spectrally adaptive and cognitive radar applications. The SAS operates from ultrahigh frequency (UHF) to the S-band and features a wideband channel with eight narrowband channels. The wideband channel acts as a monitoring channel that can be used to tune the instantaneous band of the narrowband channels to areas of interest in the spectrum. The data collected from the SAS has been utilized to develop spectrum sensing algorithms for the budding field of spectrum sharing (SS) radar. Bandwidth (BW), average total power, percent occupancy (PO), signal-to-interference-plus-noise ratio (SINR), and power spectral entropy (PSE) have been examined as metrics for the characterization of the spectrum. These metrics are utilized to determine a contiguous optimal sub-band (OSB) for a SS radar transmission in a given spectrum for different modalities. Three OSB algorithms are presented and evaluated: the spectrum sensing multi objective (SS-MO), the spectrum sensing with brute force PSE (SS-BFE), and the spectrum sensing multi-objective with brute force PSE (SS-MO-BFE).

The Spectrum Analysis Solution (SAS) System: Theoretical Analysis, Hardware Design and Implementation

PubMed Central

Pooler, Richard K.; Martone, Anthony F.; Gallagher, Kyle A.; Sherbondy, Kelly D.

2018-01-01

This paper describes a multichannel super-heterodyne signal analyzer, called the Spectrum Analysis Solution (SAS), which performs multi-purpose spectrum sensing to support spectrally adaptive and cognitive radar applications. The SAS operates from ultrahigh frequency (UHF) to the S-band and features a wideband channel with eight narrowband channels. The wideband channel acts as a monitoring channel that can be used to tune the instantaneous band of the narrowband channels to areas of interest in the spectrum. The data collected from the SAS has been utilized to develop spectrum sensing algorithms for the budding field of spectrum sharing (SS) radar. Bandwidth (BW), average total power, percent occupancy (PO), signal-to-interference-plus-noise ratio (SINR), and power spectral entropy (PSE) have been examined as metrics for the characterization of the spectrum. These metrics are utilized to determine a contiguous optimal sub-band (OSB) for a SS radar transmission in a given spectrum for different modalities. Three OSB algorithms are presented and evaluated: the spectrum sensing multi objective (SS-MO), the spectrum sensing with brute force PSE (SS-BFE), and the spectrum sensing multi-objective with brute force PSE (SS-MO-BFE). PMID:29470448

Study on a new self-sensing magnetorheological elastomer bearing

NASA Astrophysics Data System (ADS)

Li, Rui; Zhou, Mengjiao; Wang, Minglian; Yang, Ping-an

2018-06-01

The complexity of a semi-active vibration isolation system results in the difficulty of realizing its role on impact load effectively. Thus, a new self-sensing bearing based on modified anisotropic magnetorheological elastomer (MRE) is proposed in this study. This self-sensing bearing was fabricated by dispersed multi-walled carbon nanotubes and carbonyl iron particles into polydimethylsiloxane matrix under a magnetic field. The working conditions of the bearing were analyzed and decoupled. An optimal structure size of the bearing was selected and used for setting up the experiment test system. The self-sensing characteristic of the MRE bearing under the multi-field coupling of load and magnetic fields was then investigated by this test system. Results showed that the resistance of the modified MRE, in which a preload was applied by the bearing, could change approximately 28%-56% under extrusion force, mechanical force, and external magnetic field. The vibration isolation performance was tested based on the self-sensing characteristic. The bearing had excellent mechanical properties, which could reduce at least 30% of vibration. Thus, the modified MRE of the magnetorheological elastomer bearing could be simultaneously used as an actuator and a sensor.

Remote Sensing of Aerosol and their Radiative Forcing of Climate

NASA Technical Reports Server (NTRS)

Kaufman, Yoram J.; Tanre, Didier; Remer, Lorraine A.

1999-01-01

Remote sensing of aerosol and aerosol radiative forcing of climate is going through a major transformation. The launch in next few years of new satellites designed specifically for remote sensing of aerosol is expected to further revolutionized aerosol measurements: until five years ago satellites were not designed for remote sensing of aerosol. Aerosol optical thickness was derived as a by product, only over the oceans using one AVHRR channel with errors of approx. 50%. However it already revealed a very important first global picture of the distribution and sources of aerosol. In the last 5 years we saw the introduction of polarization and multi-view observations (POLDER and ATSR) for satellite remote sensing of aerosol over land and ocean. Better products are derived from AVHRR using its two channels. The new TOMS aerosol index shows the location and transport of aerosol over land and ocean. Now we anticipate the launch of EOS-Terra with MODIS, MISR and CERES on board for multi-view, multi-spectral remote sensing of aerosol and its radiative forcing. This will allow application of new techniques, e.g. using a wide spectral range (0.55-2.2 microns) to derive precise optical thickness, particle size and mass loading. Aerosol is transparent in the 2.2 microns channel, therefore this channel can be used to detect surface features that in turn are used to derive the aerosol optical thickness in the visible part of the spectrum. New techniques are developed to derive the aerosol single scattering albedo, a measure of absorption of sunlight, and techniques to derive directly the aerosol forcing at the top of the atmosphere. In the last 5 years a global network of sun/sky radiometers was formed, designed to communicate in real time the spectral optical thickness from 50-80 locations every day, every 15 minutes. The sky angular and spectral information is also measured and used to retrieve the aerosol size distribution, refractive index, single scattering albedo and the spectral flux reaching the surface. Effort to introduce remote sensing from lidars will literally additional dimension to aerosol remote sensing. The vertical dimension is a critical link between the global satellite observations and modeling of aerosol transport. Lidars are also critical to study aerosol impact on cloud microphysics and reflectance. Both lidar ground networks and satellite systems are in development. This new capability is expected to put remote sensing in the forefront of aerosol and climate studies. Together with field experiments, chemical analysis and chemical transport models we anticipate, in the next decade, to be able to resolve some of the outstanding questions regarding the role of aerosol in climate, in atmospheric chemistry and its influence on human health and life on this planet.

New Directions: Emerging Satellite Observations of Above-cloud Aerosols and Direct Radiative Forcing

NASA Technical Reports Server (NTRS)

Yu, Hongbin; Zhang, Zhibo

2013-01-01

Spaceborne lidar and passive sensors with multi-wavelength and polarization capabilities onboard the A-Train provide unprecedented opportunities of observing above-cloud aerosols and direct radiative forcing. Significant progress has been made in recent years in exploring these new aerosol remote sensing capabilities and generating unique datasets. The emerging observations will advance the understanding of aerosol climate forcing.

A force vector and surface orientation sensor for intelligent grasping

NASA Technical Reports Server (NTRS)

Mcglasson, W. D.; Lorenz, R. D.; Duffie, N. A.; Gale, K. L.

1991-01-01

The paper discusses a force vector and surface orientation sensor suitable for intelligent grasping. The use of a novel four degree-of-freedom force vector robotic fingertip sensor allows efficient, real time intelligent grasping operations. The basis of sensing for intelligent grasping operations is presented and experimental results demonstrate the accuracy and ease of implementation of this approach.

The brightness of lights on Earth at night, digitally recorded by DMSP satellite

USGS Publications Warehouse

Croft, Thomas A.

1979-01-01

The U.S. Air Force has operated its Defense Meteorological Satellite Program (DMSP) for nearly a decade, and film images from the system have been openly available since 1973. Films are well suited for the study of weather, and users of such films have derived much useful data. For many potential remote sensing applications, however, a quantitative measurement of the brightness of the imaged light patterns is needed, and it cannot be extracted with adequte accuracy from the films. Such information is contained in the telemetry from the spacecraft and is retained on digital tapes, which store the images for a few days while they await filming. For practical reasons, it has not heretofore been feasible for the Air Force to provide a remote-sensing user with these digital data, and the quantitative brightness information has been lost with the erasure of tapes for re-use. For the purpose of evaluation of tapes as a means for remote sensing, the Air Force recently did provide to the author six examples containing records of nighttime DMSP imagery similar to that which has previously 1 been evaluated by SRI International in a film format. The digital data create many new applications for these images, owing to a combination of several factors, the most important of which are the preservation of photometric information and of full spatial resolution. In this evaluation, stress has been placed upon determination of the broad potential value of the data rather than the full exploitation of any one aspect of it. The effort was guided by an objective to develop handling methods for the vast body of numbers--methods which will be practical for use in a research or engineering environment where budgets are limited, and specialized capabilities and image reproduction equipment has not already been developed. We report the degree of success obtained in this effort, pointing out the relative strengths and the relative limitations, as compared to the sophisticated, weather-oriented data processing which is well suited for the Air Force requirements. Both geometric and photometric calibration methods are evaluated. An image can be considered as a 3-dimensional array, X, Y, Z, in which X and Y are the coordinates of a picture element (pixel) and Z is the brightness at that location. A method of approach to handling these parameters, particularly Y and Z, is developed in a form quite different from that which serves the operational applications. The user of digital data will need the film images which are generated by the Air Force from the same data as is provided on digital tape. In the first stages of analysis, the films provide both a convenient index and a guide to identification of large patterns in the data. Additionally, the infrared (8 to 13 0 film provides a valuable indicator of cloud cover. Two general conclusions are drawn from this study. Firstly, the digital DMSP data have great potential value but their cost, in terms of the interruption of the present operational routine, is quite high. Therefore, if a program is undertaken to provide for the open availability of an archive of digital records, great care must be exercised in selecting only those records which have unusually high value in order that the effort will be cost-effective. Secondly, it is concluded that several aspects of the program, well designed for Air Force operational purposes, are not adapted to earth-sensing needs. This is probably inevitable, since the two applications are largely different and in some ways incompatible. For example, the nighttime visual sensor saturates in the center of major cities and in moderately large fires (such as gas flares). This saturation prevents the analyst from integrating photometric parameters. For weather observation, this inability is unimportant, and acceptance of such saturation makes feasible a decrease in the data rate. Such limitations in the data will probably be overcome only through modifying the existing system or the implementation of a similar system designed specifically to serve earth-sensing needs.

Numerical and experimental hydrodynamic analysis of suction cup bio-logging tag designs for marine mammals

NASA Astrophysics Data System (ADS)

Murray, Mark; Shorter, Alex; Howle, Laurens; Johnson, Mark; Moore, Michael

2012-11-01

The improvement and miniaturization of sensing technologies has made bio-logging tags, utilized for the study of marine mammal behavior, more practical. These sophisticated sensing packages require a housing which protects the electronics from the environment and provides a means of attachment to the animal. The hydrodynamic forces on these housings can inadvertently remove the tag or adversely affect the behavior or energetics of the animal. A modification to the original design of a suction cup bio-logging tag housing was desired to minimize the adverse forces. In this work, hydrodynamic loading of two suction cup tag designs, original and modified designs, were analyzed using computational fluid dynamics (CFD) models and validated experimentally. Overall, the simulation and experimental results demonstrated that a tag housing that minimized geometric disruptions to the flow reduced drag forces, and that a tag housing with a small frontal cross-sectional area close to the attachment surface reduced lift forces. Preliminary results from experimental work with a common dolphin cadaver indicates that the suction cups used to attach the tags to the animal provide sufficient attachment force to resist failure at predicted drag and lift forces in 10 m/s flow.

Dynamically stable magnetic suspension/bearing system

DOEpatents

Post, R.F.

1996-02-27

A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium. However, owing to the limitations imposed by Earnshaw`s Theorem, the magnetic bearing systems to be described do not possess a stable equilibrium at zero rotational speed. Therefore, mechanical stabilizers are provided, in each case, to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. The magnetic forces exerted by these elements, when taken together, levitate the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations. At the same time, this equilibrium is made stable against displacements of the rotating object from its equilibrium position by using combinations of elements that possess force derivatives of such magnitudes and signs that they can satisfy the conditions required for a rotating body to be stably supported by a magnetic bearing system over a finite range of those displacements. 32 figs.

Dynamically stable magnetic suspension/bearing system

DOEpatents

Post, Richard F.

1996-01-01

A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium. However, owing to the limitations imposed by Earnshaw's Theorem, the magnetic bearing systems to be described do not possess a stable equilibrium at zero rotational speed. Therefore, mechanical stabilizers are provided, in each case, to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. The magnetic forces exerted by these elements, when taken together, levitate the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations. At the same time, this equilibrium is made stable against displacements of the rotating object from its equilibrium position by using combinations of elements that possess force derivatives of such magnitudes and signs that they can satisfy the conditions required for a rotating body to be stably supported by a magnetic bearing system over a finite range of those displacements.

Development of micronic GMR-magnetoresistive sensors for non-destructive sensing applications (Presentation Recording)

NASA Astrophysics Data System (ADS)

Jaffrès, Henri; LeMaitre, Yves; Collin, Sophie; Nguyen Vandau, Frédéric; Sergeeva-Chollet, Natalia; Decitre, Jean-Marc

2015-09-01

We will present our last development of GMR-based magnetic sensors devoted to sensing application for non-destructive control application. In these first realizations, we have chosen a so-called shape anisotropy - exchange biased strategy to fulfill the field-sensing criteria in the μT range in devices made of micronic single elements. Our devices realized by optical lithography, and whose typical sizes range from 150 μm x 150 μm to 500 μm x 500 μm elements, are made of trilayers GMR-based technology and consist of several circuitries of GMR elements of different lengths, widths and gaps. To obtain a full sensing linearity and reversibility requiring a perpendicular magnetic arrangement between both sensitive and hard layer, the magnetization of the latter have been hardened by pinning it with an antiferromagnetic material. The specific geometry of the design have been engineered in order to optimize the magnetic response of the soft layer via the different magnetic torques exerted on it essentially played by the dipolar fields or shape anisotropy, and the external magnetic field to detect. The smaller dimensions in width and in gap are then respectively of 2 μm and 3 μm to benefit of the full shape anisotropy formatting the magnetic response.

Novel design of electrical sensing interface for prosthetic limbs using optical micro cavities

NASA Astrophysics Data System (ADS)

Ali, Amir R.; Kamel, Mohamed A.

2018-04-01

This paper uses optical whispering galley modes (WGM) cavities to construct a new electrical sensing interface between prosthetic limb and the brain. The sensing element will detect the action potential signal in the neural membrane and the prosthetic limb will be actuated accordingly. The element is a WGM dielectric polymeric cavity. WGM based optical cavities can achieve very high values of sensitivity and quality factor; thus, any minute perturbations in the morphology of the cavity can be captured and measured. The action potential signal will produce an applied external electric field on the dielectric cavity causing it to deform due to the electrostriction effect. The resulting deformation will cause WGM shifts in the transmission spectrum of the cavity. Thus, the action potential or the applied electric field can be measured using these shifts. In this paper the action potential signal will be simulated through the use of a function generator and two metal electrodes. The sensing element will be situated between these electrodes to detect the electrical signal passing through. The achieved sensitivity is 27.5 pm/V in measuring the simulated action potential signal; and 0.32 pm/V.m-1 in measuring the applied electric field due to the passage of the simulated signal.

The forced vibration of one-dimensional multi-coupled periodic structures: An application to finite element analysis

NASA Astrophysics Data System (ADS)

Mead, Denys J.

2009-01-01

A general theory for the forced vibration of multi-coupled one-dimensional periodic structures is presented as a sequel to a much earlier general theory for free vibration. Starting from the dynamic stiffness matrix of a single multi-coupled periodic element, it derives matrix equations for the magnitudes of the characteristic free waves excited in the whole structure by prescribed harmonic forces and/or displacements acting at a single periodic junction. The semi-infinite periodic system excited at its end is first analysed to provide the basis for analysing doubly infinite and finite periodic systems. In each case, total responses are found by considering just one periodic element. An already-known method of reducing the size of the computational problem is reexamined, expanded and extended in detail, involving reduction of the dynamic stiffness matrix of the periodic element through a wave-coordinate transformation. Use of the theory is illustrated in a combined periodic structure+finite element analysis of the forced harmonic in-plane motion of a uniform flat plate. Excellent agreement between the computed low-frequency responses and those predicted by simple engineering theories validates the detailed formulations of the paper. The primary purpose of the paper is not towards a specific application but to present a systematic and coherent forced vibration theory, carefully linked with the existing free-wave theory.

Workshop on The Rio Grande Rift: Crustal Modeling and Applications of Remote Sensing

NASA Technical Reports Server (NTRS)

Blanchard, D. P. (Editor)

1980-01-01

The elements of a program that could address significant earth science problems by combining remote sensing and traditional geological, geophysical, and geochemical approaches were addressed. Specific areas and tasks related to the Rio Grande Rift are discussed.

The Relationship between Teachers' Views about Cultural Values and Critical Pedagogy

ERIC Educational Resources Information Center

Yilmaz, Kursad; Altinkurt, Yahya; Ozciftci, Elif

2016-01-01

Problem Statement: Known as basic elements directing individuals' lives, cultural values are hidden cultural elements that influence all evaluations and perceptions. Values, in that sense, are elements individuals are aware of and provide the answer to the "what should I do?" feeling (Schein, 1992). Critical pedagogy is a project based…

SLUG HANDLING DEVICES

DOEpatents

Gentry, J.R.

1958-09-16

A device is described for handling fuel elements of a neutronic reactor. The device consists of two concentric telescoped contalners that may fit about the fuel element. A number of ratchet members, equally spaced about the entrance to the containers, are pivoted on the inner container and spring biased to the outer container so thnt they are forced to hear against and hold the fuel element, the weight of which tends to force the ratchets tighter against the fuel element. The ratchets are released from their hold by raising the inner container relative to the outer memeber. This device reduces the radiation hazard to the personnel handling the fuel elements.

Tool-Tissue Interaction Forces in Brain Arteriovenous Malformation Surgery.

PubMed

Sugiyama, Taku; Gan, Liu Shi; Zareinia, Kourosh; Lama, Sanju; Sutherland, Garnette R

2017-06-01

Surgical resection of a brain arteriovenous malformation (AVM) poses a technical challenge because of the fragility and number of small feeding and draining vessels around the nidus. Acquiring knowledge of the optimal force applied to such tissue is important in surgical performance and education. A force-sensing bipolar forceps was developed through installation of strain gauge sensors, and force profiles were obtained from 2 AVM surgeries. The force data associated with vessel injury, unsuccessful trial, was compared with that from successful trials. Receiver operating curve analysis was used for determining optimal force threshold and evaluating the discriminative accuracy of measurement. Force data from 519 trials was collected, of which 16 (3.1%) were unsuccessful. The mean and maximum forces in successful trials were 0.23 ± 0.06 N and 0.35 ± 0.11 N compared with unsuccessful trials of 0.33 ± 0.05 N and 0.53 ± 0.11 N, respectively (P < 0.001). There was a strong association of mean and maximum force peaks with unsuccessful trials as reflected by the area under the curve of 0.91 and 0.87, respectively. Threshold analysis showed that the rate of unsuccessful trials and error forces tended to increase with surgical time. Excessive force at the tool tip may result in injury to fragile vessels during AVM surgery. A quantifiable metric through force sensing instruments can detect and predict the occurrence of such injury. Such an instrument may be ideal for resident training and evaluation. Copyright © 2017 Elsevier Inc. All rights reserved.

Do mechanical forces contribute to nanoscale membrane organisation in T cells?

PubMed

Klotzsch, Enrico; Stiegler, Johannes; Ben-Ishay, Eldad; Gaus, Katharina

2015-04-01

Mechanotransduction describes how a cell senses and interacts with its environment. The concept originated in adhesion biology where adhesion receptors, integrins, facilitate force transmission between the extracellular matrix and the intracellular actin cytoskeleton. Indeed, during any adhesive contacts, cells do exert mechanical force. Hence, the probing of the local environment by cells results in mechanical cues that contribute to cellular functions and cell fate decisions such as migration, proliferation, differentiation and apoptosis. On the molecular level, mechanical forces can rearrange proteins laterally within the membrane, regulate their activity by inducing conformational changes and probe the mechanical properties and bond strength of receptor-ligands. From this point of view, it appears surprising that molecular forces have been largely overlooked in membrane organisation and ligand discrimination processes in lymphocytes. During T cell activation, the T cell receptor recognises and distinguishes antigenic from benign endogenous peptides to initiate the reorganisation of membrane proteins into signalling clusters within the immunological synapse. In this review, we asked whether characteristics of fibroblast force sensing could be applied to immune cell antigen recognition and signalling, and outline state-of-the-art experimental strategies for studying forces in the context of membrane organisation. This article is part of a Special Issue entitled: Nanoscale membrane orgainisation and signalling. Copyright © 2014 Elsevier B.V. All rights reserved.

MEMS-based Force-clamp Analysis of the Role of Body Stiffness in C. elegans Touch Sensation

PubMed Central

Petzold, Bryan C.; Park, Sung-Jin; Mazzochette, Eileen A.; Goodman, Miriam B.; Pruitt, Beth L.

2013-01-01

Touch is enabled by mechanoreceptor neurons in the skin and plays an essential role in our everyday lives, but is among the least understood of our five basic senses. Force applied to the skin deforms these neurons and activates ion channels within them. Despite the importance of the mechanics of the skin in determining mechanoreceptor neuron deformation and ultimately touch sensation, the role of mechanics in touch sensitivity is poorly understood. Here, we use the model organism Caenorhabditis elegans to directly test the hypothesis that body mechanics modulate touch sensitivity. We demonstrate a microelectromechanical system (MEMS)-based force clamp that can apply calibrated forces to freely crawling C. elegans worms and measure touch-evoked avoidance responses. This approach reveals that wild-type animals sense forces < 1 μN and indentation depths < 1 μm. We use both genetic manipulation of the skin and optogenetic modulation of body wall muscles to alter body mechanics. We find that small changes in body stiffness dramatically affect force sensitivity, while having only modest effects on indentation sensitivity. We investigate the theoretical body deformation predicted under applied force and conclude that local mechanical loads induce inward bending deformation of the skin to drive touch sensation in C. elegans. PMID:23598612

Temperature sensing by primary roots of maize

NASA Technical Reports Server (NTRS)

Poff, K. L.

1990-01-01

Zea mays L. seedlings, grown on agar plates at 26 degrees C, reoriented the original vertical direction of their primary root when exposed to a thermal gradient applied perpendicular to the gravity vector. The magnitude and direction of curvature can not be explained simply by either a temperature or a humidity effect on root elongation. It is concluded that primary roots of maize sense temperature gradients in addition to sensing the gravitational force.

From sense of place to visualization of place: examining people-place relationships for insight on developing geovisualizations.

PubMed

Newell, Robert; Canessa, Rosaline

2018-02-01

Effective resource planning incorporates people-place relationships, allowing these efforts to be inclusive of the different local beliefs, interests, activities and needs. 'Geovisualizations' can serve as potentially powerful tools for facilitating 'place-conscious' resource planning, as they can be developed with high degrees of realism and accuracy, allowing people to recognize and relate to them as 'real places'. However, little research has been done on this potential, and the place-based applications of these visual tools are poorly understood. This study takes steps toward addressing this gap by exploring the relationship between sense of place and 'visualization of place'. Residents of the Capital Regional District of BC, Canada, were surveyed about their relationship with local coastal places, concerns for the coast, and how they mentally visualize these places. Factor analysis identified four sense of place dimensions - nature protection values, community and economic well-being values, place identity and place dependence, and four coastal concerns dimensions - ecological, private opportunities, public space and boating impacts. Visualization data were coded and treated as dependent variables in a series of logistic regressions that used sense of place and coastal concerns dimensions as predictors. Results indicated that different aspects of sense of place and (to a lesser degree) concerns for places influence the types of elements people include in their mental visualization of place. In addition, sense of place influenced the position and perspective people assume in these visualizations. These findings suggest that key visual elements and perspectives speak to different place relationships, which has implications for developing and using geovisualizations in terms of what elements should be included in tools and (if appropriate) depicted as affected by potential management or development scenarios.

Ribo-attenuators: novel elements for reliable and modular riboswitch engineering.

PubMed

Folliard, Thomas; Mertins, Barbara; Steel, Harrison; Prescott, Thomas P; Newport, Thomas; Jones, Christopher W; Wadhams, George; Bayer, Travis; Armitage, Judith P; Papachristodoulou, Antonis; Rothschild, Lynn J

2017-07-04

Riboswitches are structural genetic regulatory elements that directly couple the sensing of small molecules to gene expression. They have considerable potential for applications throughout synthetic biology and bio-manufacturing as they are able to sense a wide range of small molecules and regulate gene expression in response. Despite over a decade of research they have yet to reach this considerable potential as they cannot yet be treated as modular components. This is due to several limitations including sensitivity to changes in genetic context, low tunability, and variability in performance. To overcome the associated difficulties with riboswitches, we have designed and introduced a novel genetic element called a ribo-attenuator in Bacteria. This genetic element allows for predictable tuning, insulation from contextual changes, and a reduction in expression variation. Ribo-attenuators allow riboswitches to be treated as truly modular and tunable components, thus increasing their reliability for a wide range of applications.

Inverse analysis of aerodynamic loads from strain information using structural models and neural networks

NASA Astrophysics Data System (ADS)

Wada, Daichi; Sugimoto, Yohei

2017-04-01

Aerodynamic loads on aircraft wings are one of the key parameters to be monitored for reliable and effective aircraft operations and management. Flight data of the aerodynamic loads would be used onboard to control the aircraft and accumulated data would be used for the condition-based maintenance and the feedback for the fatigue and critical load modeling. The effective sensing techniques such as fiber optic distributed sensing have been developed and demonstrated promising capability of monitoring structural responses, i.e., strains on the surface of the aircraft wings. By using the developed techniques, load identification methods for structural health monitoring are expected to be established. The typical inverse analysis for load identification using strains calculates the loads in a discrete form of concentrated forces, however, the distributed form of the loads is essential for the accurate and reliable estimation of the critical stress at structural parts. In this study, we demonstrate an inverse analysis to identify the distributed loads from measured strain information. The introduced inverse analysis technique calculates aerodynamic loads not in a discrete but in a distributed manner based on a finite element model. In order to verify the technique through numerical simulations, we apply static aerodynamic loads on a flat panel model, and conduct the inverse identification of the load distributions. We take two approaches to build the inverse system between loads and strains. The first one uses structural models and the second one uses neural networks. We compare the performance of the two approaches, and discuss the effect of the amount of the strain sensing information.

Modelling compression sensing in ionic polymer metal composites

NASA Astrophysics Data System (ADS)

Volpini, Valentina; Bardella, Lorenzo; Rodella, Andrea; Cha, Youngsu; Porfiri, Maurizio

2017-03-01

Ionic polymer metal composites (IPMCs) consist of an ionomeric membrane, including mobile counterions, sandwiched between two thin noble metal electrodes. IPMCs find application as sensors and actuators, where an imposed mechanical loading generates a voltage across the electrodes, and, vice versa, an imposed electric field causes deformation. Here, we present a predictive modelling approach to elucidate the dynamic sensing response of IPMCs subject to a time-varying through-the-thickness compression (‘compression sensing’). The model relies on the continuum theory recently developed by Porfiri and co-workers, which couples finite deformations to the modified Poisson-Nernst-Planck (PNP) system governing the IPMC electrochemistry. For the ‘compression sensing’ problem we establish a perturbative closed-form solution along with a finite element (FE) solution. The systematic comparison between these two solutions is a central contribution of this study, offering insight on accuracy and mathematical complexity. The method of matched asymptotic expansions is employed to find the analytical solution. To this end, we uncouple the force balance from the modified PNP system and separately linearise the PNP equations in the ionomer bulk and in the boundary layers at the ionomer-electrode interfaces. Comparison with FE results for the fully coupled nonlinear system demonstrates the accuracy of the analytical solution to describe IPMC sensing for moderate deformation levels. We finally demonstrate the potential of the modelling scheme to accurately reproduce experimental results from the literature. The proposed model is expected to aid in the design of IPMC sensors, contribute to an improved understanding of IPMC electrochemomechanical response, and offer insight into the role of nonlinear phenomena across mechanics and electrochemistry.

CoFe-microwires with stress-dependent magnetostriction as embedded sensing elements

NASA Astrophysics Data System (ADS)

Salem, M. M.; Nematov, M. G.; Uddin, A.; Panina, L. V.; Churyukanova, M. N.; Marchenko, A. T.

2017-10-01

Testing internal stress/strain condition of polymer composite materials is of high importance in structural health monitoring. We are presenting here a new method of monitoring internal stresses. The method can be referred to as embedded sensing technique, where the sensing element is a glass-coated ferromagnetic microwire with a specific magnetic anisotropy and stress-dependent magnetostriction. When the microwire is remagnetized the sharp voltage is induced which is characterized by high frequency harmonics. The amplitude of these harmonics sensitively depends on various stresses. The microwire of composition Co71Fe5B11Si10Cr3 with the metallic core diameter of 22.8 μm show abrupt transformation of the magnetization process under applied tensile stress owing to the stress-dependent magnetostriction.

Structural Truss Elements and Forces

ERIC Educational Resources Information Center

Troyer, Steve; Griffis, Kurt; Shackelford, Ray

2005-01-01

In the field of construction, most structures are supported by several groups of truss systems working together synergistically. A "truss" is a group of centered and balanced elements combined to carry a common load (Warner, 2003). Trusses provide strength against loads and forces within a structure. Though a complex field of study, structural…

Biomechanical effects of maxillary expansion on a patient with cleft palate: A finite element analysis

PubMed Central

Lee, Haofu; Nguyen, Alan; Hong, Christine; Hoang, Paul; Pham, John; Ting, Kang

2017-01-01

Introduction The aims of this study were to evaluate the effects of rapid palatal expansion on the craniofacial skeleton of a patient with unilateral cleft lip and palate (UCLP) and to predict the points of force application for optimal expansion using a 3-dimensional finite element model. Methods A 3-dimensional finite element model of the craniofacial complex with UCLP was generated from spiral computed tomographic scans with imaging software (Mimics, version 13.1; Materialise, Leuven, Belgium). This model was imported into the finite element solver (version 12.0; ANSYS, Canonsburg, Pa) to evaluate transverse expansion forces from rapid palatal expansion. Finite element analysis was performed with transverse expansion to achieve 5 mm of anterolateral expansion of the collapsed minor segment to simulate correction of the anterior crossbite in a patient with UCLP. Results High-stress concentrations were observed at the body of the sphenoid, medial to the orbit, and at the inferior area of the zygomatic process of the maxilla. The craniofacial stress distribution was asymmetric, with higher stress levels on the cleft side. When forces were applied more anteriorly on the collapsed minor segment and more posteriorly on the major segment, there was greater expansion of the anterior region of the minor segment with minimal expansion of the major segment. Conclusions The transverse expansion forces from rapid palatal expansion are distributed to the 3 maxillary buttresses. Finite element analysis is an appropriate tool to study and predict the points of force application for better controlled expansion in patients with UCLP. PMID:27476365

Biomechanical effects of maxillary expansion on a patient with cleft palate: A finite element analysis.

PubMed

Lee, Haofu; Nguyen, Alan; Hong, Christine; Hoang, Paul; Pham, John; Ting, Kang

2016-08-01

The aims of this study were to evaluate the effects of rapid palatal expansion on the craniofacial skeleton of a patient with unilateral cleft lip and palate (UCLP) and to predict the points of force application for optimal expansion using a 3-dimensional finite element model. A 3-dimensional finite element model of the craniofacial complex with UCLP was generated from spiral computed tomographic scans with imaging software (Mimics, version 13.1; Materialise, Leuven, Belgium). This model was imported into the finite element solver (version 12.0; ANSYS, Canonsburg, Pa) to evaluate transverse expansion forces from rapid palatal expansion. Finite element analysis was performed with transverse expansion to achieve 5 mm of anterolateral expansion of the collapsed minor segment to simulate correction of the anterior crossbite in a patient with UCLP. High-stress concentrations were observed at the body of the sphenoid, medial to the orbit, and at the inferior area of the zygomatic process of the maxilla. The craniofacial stress distribution was asymmetric, with higher stress levels on the cleft side. When forces were applied more anteriorly on the collapsed minor segment and more posteriorly on the major segment, there was greater expansion of the anterior region of the minor segment with minimal expansion of the major segment. The transverse expansion forces from rapid palatal expansion are distributed to the 3 maxillary buttresses. Finite element analysis is an appropriate tool to study and predict the points of force application for better controlled expansion in patients with UCLP. Copyright © 2016 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Cylindrical Asymmetrical Capacitor Devices for Space Applications

NASA Technical Reports Server (NTRS)

Campbell, Jonathan W. (Inventor)

2004-01-01

An asymmetrical capacitor system is provided which creates a thrust force. The system is adapted for use in space applications and includes a capacitor device provided with a first conductive element and a second conductive element axially spaced from the first conductive element and of smaller axial extent. A shroud supplied with gas surrounds the capacitor device. The second conductive element can be a wire ring or mesh mounted on dielectric support posts affixed to a dielectric member which separates the conductive elements or a wire or mesh annulus surrounding a barrel-shaped dielectric member on which the h t element is also mounted. A high voltage source is connected across the conductive elements and applies a high voltage to the conductive elements of sufficient value to create a thrust force on the system inducing movement thereof.

Equifinality and its violations in a redundant system: multifinger accurate force production

PubMed Central

Wilhelm, Luke; Zatsiorsky, Vladimir M.

2013-01-01

We explored a hypothesis that transient perturbations applied to a redundant system result in equifinality in the space of task-related performance variables but not in the space of elemental variables. The subjects pressed with four fingers and produced an accurate constant total force level. The “inverse piano” device was used to lift and lower one of the fingers smoothly. The subjects were instructed “not to intervene voluntarily” with possible force changes. Analysis was performed in spaces of finger forces and finger modes (hypothetical neural commands to fingers) as elemental variables. Lifting a finger led to an increase in its force and a decrease in the forces of the other three fingers; the total force increased. Lowering the finger back led to a drop in the force of the perturbed finger. At the final state, the sum of the variances of finger forces/modes computed across repetitive trials was significantly higher than the variance of the total force/mode. Most variance of the individual finger force/mode changes between the preperturbation and postperturbation states was compatible with constant total force. We conclude that a transient perturbation applied to a redundant system leads to relatively small variance in the task-related performance variable (equifinality), whereas in the space of elemental variables much more variance occurs that does not lead to total force changes. We interpret the results within a general theoretical scheme that incorporates the ideas of hierarchically organized control, control with referent configurations, synergic control, and the uncontrolled manifold hypothesis. PMID:23904497

Modelling bucket excavation by finite element

NASA Astrophysics Data System (ADS)

Pecingina, O. M.

2015-11-01

Changes in geological components of the layers from lignite pits have an impact on the sustainability of the cup path elements and under the action of excavation force appear efforts leading to deformation of the entire assembly. Application of finite element method in the optimization of components leads to economic growth, to increase the reliability and durability of the studied machine parts thus the machine. It is obvious usefulness of knowledge the state of mechanical tensions that the designed piece or the assembly not to break under the action of tensions that must cope during operation. In the course of excavation work on all bucket cutting force components, the first coming into contact with the material being excavated cutting edge. Therefore in the study with finite element analysis is retained only cutting edge. To study the field of stress and strain on the cutting edge will be created geometric patterns for each type of cup this will be subject to static analysis. The geometric design retains the cutting edge shape and on this on the tooth cassette location will apply an areal force on the abutment tooth. The cutting edge real pattern is subjected to finite element study for the worst case of rock cutting by symmetrical and asymmetrical cups whose profile is different. The purpose of this paper is to determine the displacement and tensions field for both profiles considering the maximum force applied on the cutting edge and the depth of the cutting is equal with the width of the cutting edge of the tooth. It will consider the worst case when on the structure will act both the tangential force and radial force on the bucket profile. For determination of stress and strain field on the form design of cutting edge profile will apply maximum force assuming uniform distribution and on the edge surface force will apply a radial force. After geometric patterns discretization on the cutting knives and determining stress field, can be seen that at the rectangular profile appears the "clogging" phenomenon of the cutting edge and at the polygonal profile the point of application remains constant without going inside. From the finite element method done in this paper it can be concluded that the polygonal profiles made of dihedral angles are much more durable and asymmetric cups tend to have uniform tension along the entire perimeter.

Aspirator increases relief valve poppet stroke

NASA Technical Reports Server (NTRS)

Biddle, M. E.

1967-01-01

Addition of an aspirator to a relief valve increases the valve poppet stroke under dynamic flow conditions. The aspirator allows poppet inlet dynamic forces to overcome relief valve spring force. It reduces the fluid pressure in the skirt cavity by providing a low pressure sense probe.

Optical Indoor Positioning System Based on TFT Technology

PubMed Central

Gőzse, István

2015-01-01

A novel indoor positioning system is presented in the paper. Similarly to the camera-based solutions, it is based on visual detection, but it conceptually differs from the classical approaches. First, the objects are marked by LEDs, and second, a special sensing unit is applied, instead of a camera, to track the motion of the markers. This sensing unit realizes a modified pinhole camera model, where the light-sensing area is fixed and consists of a small number of sensing elements (photodiodes), and it is the hole that can be moved. The markers are tracked by controlling the motion of the hole, such that the light of the LEDs always hits the photodiodes. The proposed concept has several advantages: Apart from its low computational demands, it is insensitive to the disturbing ambient light. Moreover, as every component of the system can be realized by simple and inexpensive elements, the overall cost of the system can be kept low. PMID:26712753

Force Limiting Vibration Tests Evaluated from both Ground Acoustic Tests and FEM Simulations of a Flight Like Vehicle System Assembly

NASA Technical Reports Server (NTRS)

Smith, Andrew; LaVerde, Bruce; Waldon, James; Hunt, Ron

2014-01-01

Marshall Space Flight Center has conducted a series of ground acoustic tests with the dual goals of informing analytical judgment, and validating analytical methods when estimating vibroacoustic responses of launch vehicle subsystems. The process of repeatedly correlating finite element-simulated responses with test-measured responses has assisted in the development of best practices for modeling and post-processing. In recent work, force transducers were integrated to measure interface forces at the base of avionics box equipment. Other force data was indirectly measured using strain gauges. The combination of these direct and indirect force measurements has been used to support and illustrate the advantages of implementing the Force Limiting approach for equipment qualification tests. The comparison of force response from integrated system level tests to measurements at the same locations during component level vibration tests provides an excellent illustration. A second comparison of the measured response cases from the system level acoustic tests to finite element simulations has also produced some principles for assessing the suitability of Finite Element Models (FEMs) for making vibroacoustics estimates. The results indicate that when FEM models are employed to guide force limiting choices, they should include sufficient detail to represent the apparent mass of the system in the frequency range of interest.

Discrete Element Method Simulation of a Boulder Extraction From an Asteroid

NASA Technical Reports Server (NTRS)

Kulchitsky, Anton K.; Johnson, Jerome B.; Reeves, David M.; Wilkinson, Allen

2014-01-01

The force required to pull 7t and 40t polyhedral boulders from the surface of an asteroid is simulated using the discrete element method considering the effects of microgravity, regolith cohesion and boulder acceleration. The connection between particle surface energy and regolith cohesion is estimated by simulating a cohesion sample tearing test. An optimal constant acceleration is found where the peak net force from inertia and cohesion is a minimum. Peak pulling forces can be further reduced by using linear and quadratic acceleration functions with up to a 40% reduction in force for quadratic acceleration.

Optimal vibration control of a rotating plate with self-sensing active constrained layer damping

NASA Astrophysics Data System (ADS)

Xie, Zhengchao; Wong, Pak Kin; Lo, Kin Heng

2012-04-01

This paper proposes a finite element model for optimally controlled constrained layer damped (CLD) rotating plate with self-sensing technique and frequency-dependent material property in both the time and frequency domain. Constrained layer damping with viscoelastic material can effectively reduce the vibration in rotating structures. However, most existing research models use complex modulus approach to model viscoelastic material, and an additional iterative approach which is only available in frequency domain has to be used to include the material's frequency dependency. It is meaningful to model the viscoelastic damping layer in rotating part by using the anelastic displacement fields (ADF) in order to include the frequency dependency in both the time and frequency domain. Also, unlike previous ones, this finite element model treats all three layers as having the both shear and extension strains, so all types of damping are taken into account. Thus, in this work, a single layer finite element is adopted to model a three-layer active constrained layer damped rotating plate in which the constraining layer is made of piezoelectric material to work as both the self-sensing sensor and actuator under an linear quadratic regulation (LQR) controller. After being compared with verified data, this newly proposed finite element model is validated and could be used for future research.

Sensing Strategies for Disambiguating among Multiple Objects in Known Poses.

DTIC Science & Technology

1985-08-01

ELEMENT. PROIECT. TASK Artificial Inteligence Laboratory AE OKUI UBR 545 Technology Square Cambridge, MA 021.39 11. CONTROLLING OFFICE NAME AND ADDRESS 12...AD-Ali65 912 SENSING STRATEGIES FOR DISAMBIGURTING MONG MULTIPLE 1/1 OBJECTS IN KNOWN POSES(U) MASSACHUSETTS INST OF TECH CAMBRIDGE ARTIFICIAL ...or Dist Special 1 ’ MASSACHUSETTS INSTITUTE OF TECHNOLOGY ARTIFICIAL INTELLIGENCE LABORATORY A. I. Memo 855 August, 1985 Sensing Strategies for

40 CFR 1042.901 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... part. Auxiliary emission control device means any element of design that senses temperature, vessel..., system, or element of design that controls or reduces the emissions of regulated pollutants from an... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF...

40 CFR 1042.901 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... part. Auxiliary emission control device means any element of design that senses temperature, vessel..., system, or element of design that controls or reduces the emissions of regulated pollutants from an... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF...

40 CFR 1042.901 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... part. Auxiliary emission control device means any element of design that senses temperature, vessel..., system, or element of design that controls or reduces the emissions of regulated pollutants from an... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF...

40 CFR 1042.901 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... part. Auxiliary emission control device means any element of design that senses temperature, vessel..., system, or element of design that controls or reduces the emissions of regulated pollutants from an... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF...

40 CFR 1037.801 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

.... Auxiliary emission control device means any element of design that senses temperature, motive speed, engine... any device, system, or element of design that controls or reduces the emissions of regulated... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF...

40 CFR 1037.801 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

.... Auxiliary emission control device means any element of design that senses temperature, motive speed, engine... any device, system, or element of design that controls or reduces the emissions of regulated... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF...

40 CFR 1042.901 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... part. Auxiliary emission control device means any element of design that senses temperature, vessel..., system, or element of design that controls or reduces the emissions of regulated pollutants from an... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF...

Monitoring of Concrete Structures Using Ofdr Technique

NASA Astrophysics Data System (ADS)

Henault, J. M.; Salin, J.; Moreau, G.; Delepine-Lesoille, S.; Bertand, J.; Taillade, F.; Quiertant, M.; Benzarti, K.

2011-06-01

Structural health monitoring is a key factor in life cycle management of infrastructures. Truly distributed fiber optic sensors are able to provide relevant information on large structures, such as bridges, dikes, nuclear power plants or nuclear waste disposal facilities. The sensing chain includes an optoelectronic unit and a sensing cable made of one or more optical fibers. A new instrument based on Optical Frequency Domain Reflectometry (OFDR), enables to perform temperature and strain measurements with a centimeter scale spatial resolution over hundred of meters and with a level of precision equal to 1 μstrain and 0.1 °C. Several sensing cables are designed with different materials targeting to last for decades in a concrete aggressive environment and to ensure an optimal transfer of temperature and strain from the concrete matrix to the optical fiber. Tests were carried out by embedding various sensing cables into plain concrete specimens and representative-scale reinforced concrete structural elements. Measurements were performed with an OFDR instrument; meanwhile, mechanical solicitations were imposed to the concrete element. Preliminary experiments are very promising since measurements performed with distributed sensing system are comparable to values obtained with conventional sensors used in civil engineering and with the Strength of Materials Modelling. Moreover, the distributed sensing system makes it possible to detect and localize cracks appearing in concrete during the mechanical loading.

(?) The Air Force Geophysics Laboratory: Aeronomy, aerospace instrumentation, space physics, meteorology, terrestrial sciences and optical physics

NASA Astrophysics Data System (ADS)

McGinty, A. B.

1982-04-01

Contents: The Air Force Geophysics Laboratory; Aeronomy Division--Upper Atmosphere Composition, Middle Atmosphere Effects, Atmospheric UV Radiation, Satellite Accelerometer Density Measurement, Theoretical Density Studies, Chemical Transport Models, Turbulence and Forcing Functions, Atmospheric Ion Chemistry, Energy Budget Campaign, Kwajalein Reference Atmospheres, 1979, Satellite Studies of the Neutral Atmosphere, Satellite Studies of the Ionosphere, Aerospace Instrumentation Division--Sounding Rocket Program, Satellite Support, Rocket and Satellite Instrumentation; Space Physics Division--Solar Research, Solar Radio Research, Environmental Effects on Space Systems, Solar Proton Event Studies, Defense Meteorological Satellite Program, Ionospheric Effects Research, Spacecraft Charging Technology; Meteorology Division--Cloud Physics, Ground-Based Remote-Sensing Techniques, Mesoscale Observing and Forecasting, Design Climatology, Aircraft Icing Program, Atmospheric Dynamics; Terrestrial Sciences Division--Geodesy and Gravity, Geokinetics; Optical Physics Division--Atmospheric Transmission, Remote Sensing, INfrared Background; and Appendices.

Stiffness Control of Surgical Continuum Manipulators

PubMed Central

Mahvash, Mohsen; Dupont, Pierre E.

2013-01-01

This paper introduces the first stiffness controller for continuum robots. The control law is based on an accurate approximation of a continuum robot’s coupled kinematic and static force model. To implement a desired tip stiffness, the controller drives the actuators to positions corresponding to a deflected robot configuration that produces the required tip force for the measured tip position. This approach provides several important advantages. First, it enables the use of robot deflection sensing as a means to both sense and control tip forces. Second, it enables stiffness control to be implemented by modification of existing continuum robot position controllers. The proposed controller is demonstrated experimentally in the context of a concentric tube robot. Results show that the stiffness controller achieves the desired stiffness in steady state, provides good dynamic performance, and exhibits stability during contact transitions. PMID:24273466

Mechanical energy absorber

NASA Technical Reports Server (NTRS)

Wesselski, Clarence J. (Inventor)

1993-01-01

An energy absorbing system for controlling the force where a moving object engages a stationary stop and where the system utilized telescopic tubular members, energy absorbing diaphragm elements, force regulating disc springs, and a return spring to return the telescoping member to its start position after stroking is presented. The energy absorbing system has frusto-conical diaphragm elements frictionally engaging the shaft and are opposed by a force regulating set of disc springs. In principle, this force feedback mechanism serves to keep the stroking load at a reasonable level even if the friction coefficient increases greatly. This force feedback device also serves to desensitize the singular and combined effects of manufacturing tolerances, sliding surface wear, temperature changes, dynamic effects, and lubricity.

Factors Influencing Learner Conceptions of Force: Exploring the Interaction among Visuospatial Ability, Motivation, and Conceptions of Newtonian Mechanics in University Undergraduates from an Evolutionary Perspective

ERIC Educational Resources Information Center

Vallett, David Bruce

2013-01-01

This study examined the relationships among visuospatial ability, motivation to learn science, and learner conceptions of force across commonly measured demographics with university undergraduates with the aim of examining the support for an evolved sense of force and motion. Demographic variables of interest included age, ethnicity, and gender,…

NMR characterization of thin films

DOEpatents

Gerald II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

2010-06-15

A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

NMR characterization of thin films

DOEpatents

Gerald, II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

2008-11-25

A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

Modeling U.S. Air Force Occupational Health Costs

DTIC Science & Technology

2009-03-01

for the 75th Aerospace Medicine Group, Hill Air Force Base, Utah. Bioenvironmental engineers sought a more robust cost comparison tool, allowing...to Major Feltenberger and Major Johns at the Air Force Medical Operations Agency and Captain Batchellor from the 75th Aerospace Medicine Squadron...resources on support functions is challenging, and rightly so. In a sense, commanders are fiduciaries to the taxpayers and must responsibly spend

Funds for the Future. Report of the Twentieth Century Fund Task Force on College and University Endowment Policy.

ERIC Educational Resources Information Center

Williamson, J. Peter

The Task Force on College and University Endowment Policy examines endowment policy in a broad context. They feel that it is important to preserve private colleges and universities and develop a sense of mission about how best to pursue this objective. The Task Force reviews policy issues faced by managers of endowment funds for institutions of…

Atomic force microscope observations of otoconia in the newt

NASA Technical Reports Server (NTRS)

Hallworth, R.; Wiederhold, M. L.; Campbell, J. B.; Steyger, P. S.

1995-01-01

Calcitic and aragonitic otoconia from the Japanese red-bellied newt, Cynops pyrrhogaster, were examined using an atomic force microscope. The surface structure of both otoconial polymorphs consisted of arrays of elements approximately 50 nm in diameter. Elements were generally round and were separated by shallow depressions of no more than 20 nm. The elements are suggested to be single crystals of calcium carbonate. The relationship of these observations to theories of otoconial genesis is discussed.

Cutting Force Predication Based on Integration of Symmetric Fuzzy Number and Finite Element Method

PubMed Central

Wang, Zhanli; Hu, Yanjuan; Wang, Yao; Dong, Chao; Pang, Zaixiang

2014-01-01

In the process of turning, pointing at the uncertain phenomenon of cutting which is caused by the disturbance of random factors, for determining the uncertain scope of cutting force, the integrated symmetric fuzzy number and the finite element method (FEM) are used in the prediction of cutting force. The method used symmetric fuzzy number to establish fuzzy function between cutting force and three factors and obtained the uncertain interval of cutting force by linear programming. At the same time, the change curve of cutting force with time was directly simulated by using thermal-mechanical coupling FEM; also the nonuniform stress field and temperature distribution of workpiece, tool, and chip under the action of thermal-mechanical coupling were simulated. The experimental result shows that the method is effective for the uncertain prediction of cutting force. PMID:24790556

Psychophysical evidence for the number sense.

PubMed

Burr, David C; Anobile, Giovanni; Arrighi, Roberto

2017-02-19

It is now clear that most animals, including humans, possess an ability to rapidly estimate number. Some have questioned whether this ability arises from dedicated numerosity mechanisms, or is derived indirectly from judgements of density or other attributes. We describe a series of psychophysical experiments, largely using adaptation techniques, which demonstrate clearly the existence of a number sense in humans. The number sense is truly general, extending over space, time and sensory modality, and is closely linked with action. We further show that when multiple cues are present, numerosity emerges as the natural dimension for discrimination. However, when element density increases past a certain level, the elements become too crowded to parse, and the scene is perceived as a texture rather than array of elements. The two different regimes are psychophysically discriminable in that they follow distinct psychophysical laws, and show different dependencies on eccentricity, luminance levels and effects of perceptual grouping. The distinction is important, as the ability to discriminate numerosity, but not texture, correlates with formal maths skills.This article is part of the discussion meeting issue 'The origins of numerical abilities'. © 2017 The Authors.