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Sample records for reaction forces measured

  1. Ambulatory Measurement of Ground Reaction Forces

    NARCIS (Netherlands)

    Veltink, Peter H.; Liedtke, Christian; Droog, Ed

    2004-01-01

    The measurement of ground reaction forces is important in the biomechanical analysis of gait and other motor activities. It is the purpose of this study to show the feasibility of ambulatory measurement of ground reaction forces using two six degrees of freedom sensors mounted under the shoe. One

  2. Ambulatory measurement of ground reaction force and estimation of ankle and foot dynamics

    NARCIS (Netherlands)

    Schepers, H. Martin; Koopman, Hubertus F.J.M.; Baten, Christian T.M.; Veltink, Petrus H.

    INTRODUCTION Traditionally, human body movement analysis is done in so-called ‘gait laboratories’. In these laboratories, body movement is measured by a camera system using optical markers, the ground reaction force by a force plate fixed in the floor, and the muscle activity by EMG. From the body

  3. Use of a tibial accelerometer to measure ground reaction force in running: A reliability and validity comparison with force plates.

    Science.gov (United States)

    Raper, Damian P; Witchalls, Jeremy; Philips, Elissa J; Knight, Emma; Drew, Michael K; Waddington, Gordon

    2018-01-01

    The use of microsensor technologies to conduct research and implement interventions in sports and exercise medicine has increased recently. The objective of this paper was to determine the validity and reliability of the ViPerform as a measure of load compared to vertical ground reaction force (GRF) as measured by force plates. Absolute reliability assessment, with concurrent validity. 10 professional triathletes ran 10 trials over force plates with the ViPerform mounted on the mid portion of the medial tibia. Calculated vertical ground reaction force data from the ViPerform was matched to the same stride on the force plate. Bland-Altman (BA) plot of comparative measure of agreement was used to assess the relationship between the calculated load from the accelerometer and the force plates. Reliability was calculated by intra-class correlation coefficients (ICC) with 95% confidence intervals. BA plot indicates minimal agreement between the measures derived from the force plate and ViPerform, with variation at an individual participant plot level. Reliability was excellent (ICC=0.877; 95% CI=0.825-0.917) in calculating the same vertical GRF in a repeated trial. Standard error of measure (SEM) equalled 99.83 units (95% CI=82.10-119.09), which, in turn, gave a minimum detectable change (MDC) value of 276.72 units (95% CI=227.32-330.07). The ViPerform does not calculate absolute values of vertical GRF similar to those measured by a force plate. It does provide a valid and reliable calculation of an athlete's lower limb load at constant velocity. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  4. A nondestructive, reproducible method of measuring joint reaction force at the distal radioulnar joint.

    Science.gov (United States)

    Canham, Colin D; Schreck, Michael J; Maqsoodi, Noorullah; Doolittle, Madison; Olles, Mark; Elfar, John C

    2015-06-01

    To develop a nondestructive method of measuring distal radioulnar joint (DRUJ) joint reaction force (JRF) that preserves all periarticular soft tissues and more accurately reflects in vivo conditions. Eight fresh-frozen human cadaveric limbs were obtained. A threaded Steinmann pin was placed in the middle of the lateral side of the distal radius transverse to the DRUJ. A second pin was placed into the middle of the medial side of the distal ulna colinear to the distal radial pin. Specimens were mounted onto a tensile testing machine using a custom fixture. A uniaxial distracting force was applied across the DRUJ while force and displacement were simultaneously measured. Force-displacement curves were generated and a best-fit polynomial was solved to determine JRF. All force-displacement curves demonstrated an initial high slope where relatively large forces were required to distract the joint. This ended with an inflection point followed by a linear area with a low slope, where small increases in force generated larger amounts of distraction. Each sample was measured 3 times and there was high reproducibility between repeated measurements. The average baseline DRUJ JRF was 7.5 N (n = 8). This study describes a reproducible method of measuring DRUJ reaction forces that preserves all periarticular stabilizing structures. This technique of JRF measurement may also be suited for applications in the small joints of the wrist and hand. Changes in JRF can alter native joint mechanics and lead to pathology. Reliable methods of measuring these forces are important for determining how pathology and surgical interventions affect joint biomechanics. Copyright © 2015 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  5. A wearable force plate system for the continuous measurement of triaxial ground reaction force in biomechanical applications

    International Nuclear Information System (INIS)

    Liu, Tao; Inoue, Yoshio; Shibata, Kyoko

    2010-01-01

    The ambulatory measurement of ground reaction force (GRF) and human motion under free-living conditions is convenient, inexpensive and never restricted to gait analysis in a laboratory environment and is therefore much desired by researchers and clinical doctors in biomedical applications. A wearable force plate system was developed by integrating small triaxial force sensors and three-dimensional (3D) inertial sensors for estimating dynamic triaxial GRF in biomechanical applications. The system, in comparison to existent systems, is characterized by being lightweight, thin and easy-to-wear. A six-axial force sensor (Nitta Co., Japan) was used as a verification measurement device to validate the static accuracy of the developed force plate. To evaluate the precision during dynamic gait measurements, we compared the measurements of the triaxial GRF and the center of pressure (CoP) by using the developed system with the reference measurements made using a stationary force plate and an optical motion analysis system. The root mean square (RMS) differences of the two transverse components (x- and y-axes) and the vertical component (z-axis) of the GRF were 4.3 ± 0.9 N, 6.0 ± 1.3 N and 12.1 ± 1.1 N, respectively, corresponding to 5.1 ± 1.1% and 6.5 ± 1% of the maximum of each transverse component and 1.3 ± 0.2% of the maximum vertical component of GRF. The RMS distance between the two systems' CoP traces was 3.2 ± 0.8 mm, corresponding to 1.2 ± 0.3% of the length of the shoe. Moreover, based on the results of the assessment of the influence of the system on natural gait, we found that gait was almost never affected. Therefore, the wearable system as an alternative device can be a potential solution for measuring CoP and triaxial GRF in non-laboratory environments

  6. MEMS two-axis force plate array used to measure the ground reaction forces during the running motion of an ant

    International Nuclear Information System (INIS)

    Takahashi, Hidetoshi; Thanh-Vinh, Nguyen; Jung, Uijin G; Shimoyama, Isao; Matsumoto, Kiyoshi

    2014-01-01

    A terrestrial insect can perform agile running maneuvers. However, the balance of ground reaction forces (GRFs) between each leg in an insect have remained poorly characterized. In this report, we present a micro force plate array for the simultaneous measurement of the anterior and vertical components of GRFs of multiple legs during the running motion of an ant. The proposed force plate, which consists of a 2000 µm × 980 µm × 20 µm plate base as the contact surface of an ant's leg, and the supported beams with piezoresistors on the sidewall and surface are sufficiently compact to be adjacently arrayed along the anterior direction. Eight plates arrayed in parallel were fabricated on the same silicon-on-insulator substrate to narrow the gap between each plate to 20 µm. We compartmented the plate surface into 32 blocks and evaluated the sensitivities to two-axis forces in each block so that the exerted forces could be detected wherever a leg came into contact. The force resolutions in both directions were under 1 µN within ±20 µN. Using the fabricated force plate array, we achieved a simultaneous measurement of the GRFs of three legs on one side while an ant was running. (paper)

  7. A New Proxy Measurement Algorithm with Application to the Estimation of Vertical Ground Reaction Forces Using Wearable Sensors.

    Science.gov (United States)

    Guo, Yuzhu; Storm, Fabio; Zhao, Yifan; Billings, Stephen A; Pavic, Aleksandar; Mazzà, Claudia; Guo, Ling-Zhong

    2017-09-22

    Measurement of the ground reaction forces (GRF) during walking is typically limited to laboratory settings, and only short observations using wearable pressure insoles have been reported so far. In this study, a new proxy measurement method is proposed to estimate the vertical component of the GRF (vGRF) from wearable accelerometer signals. The accelerations are used as the proxy variable. An orthogonal forward regression algorithm (OFR) is employed to identify the dynamic relationships between the proxy variables and the measured vGRF using pressure-sensing insoles. The obtained model, which represents the connection between the proxy variable and the vGRF, is then used to predict the latter. The results have been validated using pressure insoles data collected from nine healthy individuals under two outdoor walking tasks in non-laboratory settings. The results show that the vGRFs can be reconstructed with high accuracy (with an average prediction error of less than 5.0%) using only one wearable sensor mounted at the waist (L5, fifth lumbar vertebra). Proxy measures with different sensor positions are also discussed. Results show that the waist acceleration-based proxy measurement is more stable with less inter-task and inter-subject variability than the proxy measures based on forehead level accelerations. The proposed proxy measure provides a promising low-cost method for monitoring ground reaction forces in real-life settings and introduces a novel generic approach for replacing the direct determination of difficult to measure variables in many applications.

  8. A New Proxy Measurement Algorithm with Application to the Estimation of Vertical Ground Reaction Forces Using Wearable Sensors

    Directory of Open Access Journals (Sweden)

    Yuzhu Guo

    2017-09-01

    Full Text Available Measurement of the ground reaction forces (GRF during walking is typically limited to laboratory settings, and only short observations using wearable pressure insoles have been reported so far. In this study, a new proxy measurement method is proposed to estimate the vertical component of the GRF (vGRF from wearable accelerometer signals. The accelerations are used as the proxy variable. An orthogonal forward regression algorithm (OFR is employed to identify the dynamic relationships between the proxy variables and the measured vGRF using pressure-sensing insoles. The obtained model, which represents the connection between the proxy variable and the vGRF, is then used to predict the latter. The results have been validated using pressure insoles data collected from nine healthy individuals under two outdoor walking tasks in non-laboratory settings. The results show that the vGRFs can be reconstructed with high accuracy (with an average prediction error of less than 5.0% using only one wearable sensor mounted at the waist (L5, fifth lumbar vertebra. Proxy measures with different sensor positions are also discussed. Results show that the waist acceleration-based proxy measurement is more stable with less inter-task and inter-subject variability than the proxy measures based on forehead level accelerations. The proposed proxy measure provides a promising low-cost method for monitoring ground reaction forces in real-life settings and introduces a novel generic approach for replacing the direct determination of difficult to measure variables in many applications.

  9. Hoof accelerations and ground reaction forces of Thoroughbred racehorses measured on dirt, synthetic, and turf track surfaces.

    Science.gov (United States)

    Setterbo, Jacob J; Garcia, Tanya C; Campbell, Ian P; Reese, Jennifer L; Morgan, Jessica M; Kim, Sun Y; Hubbard, Mont; Stover, Susan M

    2009-10-01

    To compare hoof acceleration and ground reaction force (GRF) data among dirt, synthetic, and turf surfaces in Thoroughbred racehorses. 3 healthy Thoroughbred racehorses. Forelimb hoof accelerations and GRFs were measured with an accelerometer and a dynamometric horseshoe during trot and canter on dirt, synthetic, and turf track surfaces at a racecourse. Maxima, minima, temporal components, and a measure of vibration were extracted from the data. Acceleration and GRF variables were compared statistically among surfaces. The synthetic surface often had the lowest peak accelerations, mean vibration, and peak GRFs. Peak acceleration during hoof landing was significantly smaller for the synthetic surface (mean + or - SE, 28.5g + or - 2.9g) than for the turf surface (42.9g + or - 3.8g). Hoof vibrations during hoof landing for the synthetic surface were dirt and turf surfaces. Peak GRF for the synthetic surface (11.5 + or - 0.4 N/kg) was 83% and 71% of those for the dirt (13.8 + or - 0.3 N/kg) and turf surfaces (16.1 + or - 0.7 N/kg), respectively. The relatively low hoof accelerations, vibrations, and peak GRFs associated with the synthetic surface evaluated in the present study indicated that synthetic surfaces have potential for injury reduction in Thoroughbred racehorses. However, because of the unique material properties and different nature of individual dirt, synthetic, and turf racetrack surfaces, extending the results of this study to encompass all track surfaces should be done with caution.

  10. Self-Described Differences Between Legs in Ballet Dancers: Do They Relate to Postural Stability and Ground Reaction Force Measures?

    Science.gov (United States)

    Mertz, Laura; Docherty, Carrie

    2012-12-01

    Ballet technique classes are designed to train dancers symmetrically, but they may actually create a lateral bias. It is unknown whether dancers in general are functionally asymmetrical, or how an individual dancer's perceived imbalance between legs might manifest itself. The purpose of this study was to examine ballet dancers' lateral preference by analyzing their postural stability and ground reaction forces in fifth position when landing from dance-specific jumps. Thirty university ballet majors volunteered to participate in this study. The subjects wore their own ballet technique shoes and performed fundamental ballet jumps out of fifth position on a force plate. The force plate recorded center of pressure (COP) and ground reaction force (GRF) data. Each subject completed a laterality questionnaire that determined his or her preferred landing leg for ballet jumps, self-identified stronger leg, and self-identified leg with better balance. All statistical comparisons were made between the leg indicated on the laterality questionnaire and the other leg (i.e., if the dancer's response to a question was "left," the comparison was made with the left leg as the "preferred" leg and the right leg as the "non-preferred leg"). No significant differences were identified between the limbs in any of the analyses conducted (all statistical comparisons produced p values > 0.05). The results of this study indicate that a dancer's preferential use of one limb over the other has no bearing on GRFs or balance ability after landing jumps in ballet. Similarly, dancers' opinions of their leg characteristics (such as one leg being stronger than the other) seem not to correlate with the dancers' actual ability to absorb GRFs or to balance when landing from ballet jumps.

  11. Estimation of ground reaction forces and joint moments on the basis on plantar pressure insoles and wearable sensors for joint angle measurement.

    Science.gov (United States)

    Ostaszewski, Michal; Pauk, Jolanta

    2018-05-16

    Gait analysis is a useful tool medical staff use to support clinical decision making. There is still an urgent need to develop low-cost and unobtrusive mobile health monitoring systems. The goal of this study was twofold. Firstly, a wearable sensor system composed of plantar pressure insoles and wearable sensors for joint angle measurement was developed. Secondly, the accuracy of the system in the measurement of ground reaction forces and joint moments was examined. The measurements included joint angles and plantar pressure distribution. To validate the wearable sensor system and examine the effectiveness of the proposed method for gait analysis, an experimental study on ten volunteer subjects was conducted. The accuracy of measurement of ground reaction forces and joint moments was validated against the results obtained from a reference motion capture system. Ground reaction forces and joint moments measured by the wearable sensor system showed a root mean square error of 1% for min. GRF and 27.3% for knee extension moment. The correlation coefficient was over 0.9, in comparison with the stationary motion capture system. The study suggests that the wearable sensor system could be recommended both for research and clinical applications outside a typical gait laboratory.

  12. Three-Axis Ground Reaction Force Distribution during Straight Walking.

    Science.gov (United States)

    Hori, Masataka; Nakai, Akihito; Shimoyama, Isao

    2017-10-24

    We measured the three-axis ground reaction force (GRF) distribution during straight walking. Small three-axis force sensors composed of rubber and sensor chips were fabricated and calibrated. After sensor calibration, 16 force sensors were attached to the left shoe. The three-axis force distribution during straight walking was measured, and the local features of the three-axis force under the sole of the shoe were analyzed. The heel area played a role in receiving the braking force, the base area of the fourth and fifth toes applied little vertical or shear force, the base area of the second and third toes generated a portion of the propulsive force and received a large vertical force, and the base area of the big toe helped move the body's center of mass to the other foot. The results demonstrate that measuring the three-axis GRF distribution is useful for a detailed analysis of bipedal locomotion.

  13. Interfacial force measurements using atomic force microscopy

    NARCIS (Netherlands)

    Chu, L.

    2018-01-01

    Atomic Force Microscopy (AFM) can not only image the topography of surfaces at atomic resolution, but can also measure accurately the different interaction forces, like repulsive, adhesive and lateral existing between an AFM tip and the sample surface. Based on AFM, various extended techniques have

  14. Comparison of vertical ground reaction forces during overground and treadmill running. A validation study

    NARCIS (Netherlands)

    Kluitenberg, Bas; Bredeweg, Steef W.; Zijlstra, Sjouke; Zijlstra, Wiebren; Buist, Ida

    2012-01-01

    Background: One major drawback in measuring ground-reaction forces during running is that it is time consuming to get representative ground-reaction force (GRF) values with a traditional force platform. An instrumented force measuring treadmill can overcome the shortcomings inherent to overground

  15. Force, reaction time, and precision of Kung Fu strikes.

    Science.gov (United States)

    Neto, Osmar Pinto; Bolander, Richard; Pacheco, Marcos Tadeu Tavares; Bir, Cynthia

    2009-08-01

    The goal was to compare values of force, precision, and reaction time of several martial arts punches and palm strikes performed by advanced and intermediate Kung Fu practitioners, both men and women. 13 Kung Fu practitioners, 10 men and three women, participated. Only the men, three advanced and seven intermediate, were considered for comparisons between levels. Reaction time values were obtained using two high speed cameras that recorded each strike at 2500 Hz. Force of impact was measured by a load cell. For comparisons of groups, force data were normalized by participant's body mass and height. Precision of the strikes was determined by a high speed pressure sensor. The results show that palm strikes were stronger than punches. Women in the study presented, on average, lower values of reaction time and force but higher values of precision than men. Advanced participants presented higher forces than intermediate participants. Significant negative correlations between the values of force and precision and the values of force and reaction time were also found.

  16. A vacuum--generated inertia reaction force

    International Nuclear Information System (INIS)

    Rueda, Alfonso; Haisch, Bernard

    2001-01-01

    A clear and succinct covariant approach shows that, in principle, there must be a contribution to the inertia reaction force on an accelerated object by the surrounding vacuum electromagnetic field in which the object is embedded. No details of the vacuum to object electromagnetic interaction need to be specified other than the fact that the object is made of electromagnetically interacting particles. Some interesting consequences of this feature are discussed. This analysis strongly supports the concept that inertia is indeed an opposition of the vacuum fields to any attempt to change the uniform state of motion of material bodies. This also definitely shows that inertia should be viewed as extrinsic to mass and that causing agents and/or mechanisms responsible for the inertia reaction force are neither intrinsic to the notion of mass nor to the entities responsible for the existence of mass in elementary particles (as, e.g., the Higgs field). In other words the mechanism that produces the inertia-reaction-force requires an explicit explanation. This explicit explanation is that inertia is an opposition of the vacuum fields to the accelerated motion of any material entities, i.e., of entities that possess mass. It is briefly commented why the existence of a Higgs field responsible for the generation of mass in elementary particles does not contradict the view presented here. It is also briefly discussed why a strict version of Mach's Principle does really contradict this view, though a broad sense version of Mach's Principle may be in agreement

  17. Nuclear reaction matrix and nuclear forces

    International Nuclear Information System (INIS)

    Nagata, Sinobu; Bando, Hiroharu; Akaishi, Yoshinori.

    1979-01-01

    An essentially exact method of solution is presented for the reaction- matrix (G-matrix) equation defined with the orthogonalized plane-wave intermediate spectrum for high-lying two-particle states. The accuracy is examined for introduced truncations and also in comparison with the Tsai-Kuo and Sauer methods. Properties of the G-matrix are discussed with emphasis on the relation with the saturation mechanism, especially overall saturation from light to heavy nuclei. Density and starting-energy dependences of the G-matrix are separately extracted and discussed. It is demonstrated that the triplet-even tensor component of the nuclear force is principally responsible for these dependences and hence for the saturation mechanism. In this context different nuclear potentials are used in the renormalized Brueckner calculation for energies of closed-shell nuclei in the harmonic oscillator basis. A semi-phenomenological ''two-body potential'' is devised so that it can reproduce the saturation energies and densities of nuclear matter and finite nuclei in the lowest-order Brueckner treatment. It is composed of a realistic N-N potential and two additional parts; one incorporates the three-body force effect and the other is assumed to embody higher-cluster correlations in G. The tensor component in the triplet-even state of this potential is enhanced by the three-body force effect. The G-matrix is represented in the effective local form and decomposed into central, LS and tensor components. (author)

  18. Study of Reaction Forces in a Single Sided Linear Induction Motor (SLIM)

    Science.gov (United States)

    1974-01-01

    SLIM reaction forces were measured on a laboratory model having aluminum and aluminum-iron secondaries and the results were correlated with the theoretical forces derived for different idealized SLIM models. The first part of the report discusses wav...

  19. System of gait analysis based on ground reaction force assessment

    Directory of Open Access Journals (Sweden)

    František Vaverka

    2015-12-01

    Full Text Available Background: Biomechanical analysis of gait employs various methods used in kinematic and kinetic analysis, EMG, and others. One of the most frequently used methods is kinetic analysis based on the assessment of the ground reaction forces (GRF recorded on two force plates. Objective: The aim of the study was to present a method of gait analysis based on the assessment of the GRF recorded during the stance phase of two steps. Methods: The GRF recorded with a force plate on one leg during stance phase has three components acting in directions: Fx - mediolateral, Fy - anteroposterior, and Fz - vertical. A custom-written MATLAB script was used for gait analysis in this study. This software displays instantaneous force data for both legs as Fx(t, Fy(t and Fz(t curves, automatically determines the extremes of functions and sets the visual markers defining the individual points of interest. Positions of these markers can be easily adjusted by the rater, which may be necessary if the GRF has an atypical pattern. The analysis is fully automated and analyzing one trial takes only 1-2 minutes. Results: The method allows quantification of temporal variables of the extremes of the Fx(t, Fy(t, Fz(t functions, durations of the braking and propulsive phase, duration of the double support phase, the magnitudes of reaction forces in extremes of measured functions, impulses of force, and indices of symmetry. The analysis results in a standardized set of 78 variables (temporal, force, indices of symmetry which can serve as a basis for further research and diagnostics. Conclusions: The resulting set of variable offers a wide choice for selecting a specific group of variables with consideration to a particular research topic. The advantage of this method is the standardization of the GRF analysis, low time requirements allowing rapid analysis of a large number of trials in a short time, and comparability of the variables obtained during different research measurements.

  20. Automatic HTS force measurement instrument

    International Nuclear Information System (INIS)

    Sanders, S.T.; Niemann, R.C.

    1999-01-01

    A device is disclosed for measuring the levitation force of a high temperature superconductor sample with respect to a reference magnet includes a receptacle for holding several high temperature superconductor samples each cooled to superconducting temperature. A rotatable carousel successively locates a selected one of the high temperature superconductor samples in registry with the reference magnet. Mechanism varies the distance between one of the high temperature superconductor samples and the reference magnet, and a sensor measures levitation force of the sample as a function of the distance between the reference magnet and the sample. A method is also disclosed. 3 figs

  1. Surface chemical reactions probed with scanning force microscopy

    NARCIS (Netherlands)

    Werts, M.P L; van der Vegte, E.W.; Hadziioannou, G

    1997-01-01

    In this letter we report the study of surface chemical reactions with scanning force microscopy (SFM) with chemical specificity. Using chemically modified SFM probes, we can determine the local surface reaction conversion during a chemical surface modification. The adhesion forces between a

  2. Muscle response to pneumatic hand tool torque reaction forces.

    Science.gov (United States)

    Radwin, R G; VanBergeijk, E; Armstrong, T J

    1989-06-01

    Surface electromyography was used for studying the effects of torque reaction force acting against the hand, on forearm muscle activity and grip force for five subjects operating right angle, air shut-off nutrunners. Four tools having increasing spindle torque were operated using short and long torque reaction times. Nutrunner spindle torque ranged between 30 Nm and 100 Nm. Short torque reaction time was considered 0.5 s while long torque reaction time was 2 s. Peak horizontal force was the greatest component of the reaction force acting against the hand and accounted for more than 97% of the peak resultant hand force. Peak hand force increased from 89 N for the smallest tool to 202 N for the largest tool. Forearm muscle rms EMG, scaled for grip force, indicated average flexor activity during the Torque-reaction phase was more than four times greater than the Pre-start and Post Shut-off phases, and two times greater than the Run-down phase. Flexor EMG activity during the Torque-reaction phase increased for increasing tool peak spindle torque. Average flexor rms EMG activity, scaled for grip force, during the Torque-reaction phase increased from 372 N for the 30 Nm nutrunner to 449 N for the 100 Nm nutrunner. Flexor rms EMG activity averaged during the Torque-reaction phase and scaled for grip force was 390 N for long torque reaction times and increased to 440 N for short torque reaction times. Flexor rms EMG integrated over the torque reaction phase was 839 Ns for long torque reaction times and decreased to 312 Ns for short torque reaction times. The average latency between tool spindle torque onset and peak initial flexor rms EMG for long torque reaction times was 294 ms which decreased to 161 ms for short torque reaction times. The average latency between peak tool spindle torque, just prior to tool shut-off, and peak final rms EMG for long torque reaction times was 97 ms for flexors and 188 ms for extensors, which decreased for short torque reaction times to 47

  3. Forelimb and hindlimb ground reaction forces of walking cats: Assessment and comparison with walking dogs

    NARCIS (Netherlands)

    Corbee, R.J.; Maas, H.; Doornenbal, A; Hazewinkel, H.A.W.

    2014-01-01

    The primary aim of this study was to assess the potential of force plate analysis for describing the stride cycle of the cat. The secondary aim was to define differences in feline and canine locomotion based on force plate characteristics. Ground reaction forces of 24 healthy cats were measured and

  4. Ground Reaction Forces During Reduced Gravity Running in Parabolic Flight.

    Science.gov (United States)

    Cavanagh, Peter; Rice, Andrea; Glauberman, Molly; Sudduth, Amanda; Cherones, Arien; Davis, Shane; Lewis, Michael; Hanson, Andrea; Wilt, Grier

    2017-08-01

    Treadmills have been employed as both a form of exercise and a countermeasure to prevent changes in the musculoskeletal system on almost all NASA missions and many Russian missions since the early Space Shuttle flights. It is possible that treadmills may also be part of exercise programs on future Mars missions and that they may be a component of exercise facilities in lunar or Martian habitats. In order to determine if the ambient gravity on these destinations will provide osteogenic effects while performing exercise on a treadmill, ground reactions forces (GRFs) were measured on eight subjects (six women and two men) running at 6 mph during parabolic flight in Martian and lunar gravity conditions. On average, stride length increased as gravity decreased. The first and second peaks of the GRFs decreased by 0.156 and 0.196 bodyweights, respectively, per 1/10 g change in ambient gravity. Based on comparisons with previously measured GRF during loaded treadmill running on the International Space Station, we conclude that unloaded treadmill running under lunar and Martian conditions during exploration missions is not likely to be an osteo-protective exercise.Cavanagh P, Rice A, Glauberman M, Sudduth A, Cherones A, Davis S, Lewis M, Hanson A, Wilt G. Ground reaction forces during reduced gravity running in parabolic flight. Aerosp Med Hum Perform. 2017; 88(8):730-736.

  5. Can shoulder joint reaction forces be estimated by neural networks?

    NARCIS (Netherlands)

    de Vries, W.H.K.; Veeger, H.E.J.; Baten, C.T.M.; van der Helm, F.C.T.

    2016-01-01

    To facilitate the development of future shoulder endoprostheses, a long term load profile of the shoulder joint is desired. A musculoskeletal model using 3D kinematics and external forces as input can estimate the mechanical load on the glenohumeral joint, in terms of joint reaction forces. For long

  6. Ground reaction force characteristics of Tai Chi push hand.

    Science.gov (United States)

    Chang, Yao-Ting; Chang, Jia-Hao; Huang, Chen-Fu

    2014-01-01

    Push Hand is an advanced training technique for the Yang-style old frame 108 forms Tai Chi Chuan. It is performed by two practitioners. To clarify how people use forces during Push Hand training, it is important to review the ground reaction force (GRF). Here, we quantify the characteristics of the GRF during Push Hand training. Kinematic data and GRF data from 10 Tai Chi Chuan practitioners (29.9 ± 7.87 years) were synchronously recorded using a three-dimensional motion analysis system (200 frames · s(-1)) and three-dimensional force plates (1000 Hz). The resultant GRF for both feet for the 0%, 50% and 100% phases of attack and defence were compared to body weight using a paired-samples t-test. The differences in the resultant GRF between the 0%, 50% and 100% phases of attack and defence were tested by one-way repeated-measures ANOVA. The significance level was set to 0.05. The total resultant GRF was almost equal to the participant's body weight in push hand. This result was consistent throughout the entire push hand process. Our results revealed that the GRF was comparable to the body weight, implying that practitioners do not push or resist their opponents during the push hand process.

  7. Direct measurements of intermolecular forces by chemical force microscopy

    Science.gov (United States)

    Vezenov, Dmitri Vitalievich

    1999-12-01

    Detailed description of intermolecular forces is key to understanding a wide range of phenomena from molecular recognition to materials failure. The unique features of atomic force microscopy (AFM) to make point contact force measurements with ultra high sensitivity and to generate spatial maps of surface topography and forces have been extended to include measurements between well-defined organic molecular groups. Chemical modification of AFM probes with self-assembled monolayers (SAMs) was used to make them sensitive to specific molecular interactions. This novel chemical force microscopy (CFM) technique was used to probe forces between different molecular groups in a range of environments (vacuum, organic liquids and aqueous solutions); measure surface energetics on a nanometer scale; determine pK values of the surface acid and base groups; measure forces to stretch and unbind a short synthetic DNA duplex and map the spatial distribution of specific functional groups and their ionization state. Studies of adhesion forces demonstrated the important contribution of hydrogen bonding to interactions between simple organic functionalities. The chemical identity of the tip and substrate surfaces as well as the medium had a dramatic effect on adhesion between model monolayers. A direct correlation between surface free energy and adhesion forces was established. The adhesion between epoxy polymer and model mixed SAMs varied with the amount of hydrogen bonding component in the monolayers. A consistent interpretation of CFM measurements in polar solvents was provided by contact mechanics models and intermolecular force components theory. Forces between tips and surfaces functionalized with SAMs terminating in acid or base groups depended on their ionization state. A novel method of force titration was introduced for highly local characterization of the pK's of surface functional groups. The pH-dependent changes in friction forces were exploited to map spatially the

  8. Comparison of vertical ground reaction forces during overground and treadmill running. A validation study

    Directory of Open Access Journals (Sweden)

    Kluitenberg Bas

    2012-11-01

    Full Text Available Abstract Background One major drawback in measuring ground-reaction forces during running is that it is time consuming to get representative ground-reaction force (GRF values with a traditional force platform. An instrumented force measuring treadmill can overcome the shortcomings inherent to overground testing. The purpose of the current study was to determine the validity of an instrumented force measuring treadmill for measuring vertical ground-reaction force parameters during running. Methods Vertical ground-reaction forces of experienced runners (12 male, 12 female were obtained during overground and treadmill running at slow, preferred and fast self-selected running speeds. For each runner, 7 mean vertical ground-reaction force parameters of the right leg were calculated based on five successful overground steps and 30 seconds of treadmill running data. Intraclass correlations (ICC(3,1 and ratio limits of agreement (RLOA were used for further analysis. Results Qualitatively, the overground and treadmill ground-reaction force curves for heelstrike runners and non-heelstrike runners were very similar. Quantitatively, the time-related parameters and active peak showed excellent agreement (ICCs between 0.76 and 0.95, RLOA between 5.7% and 15.5%. Impact peak showed modest agreement (ICCs between 0.71 and 0.76, RLOA between 19.9% and 28.8%. The maximal and average loading-rate showed modest to excellent ICCs (between 0.70 and 0.89, but RLOA were higher (between 34.3% and 45.4%. Conclusions The results of this study demonstrated that the treadmill is a moderate to highly valid tool for the assessment of vertical ground-reaction forces during running for runners who showed a consistent landing strategy during overground and treadmill running. The high stride-to-stride variance during both overground and treadmill running demonstrates the importance of measuring sufficient steps for representative ground-reaction force values. Therefore, an

  9. Factors influencing power hand tool fastening accuracy and reaction forces.

    Science.gov (United States)

    Radwin, Robert G; Chourasia, Amrish O; Howery, Robert S; Fronczak, Frank J; Yen, Thomas Y; Subedi, Yashpal; Sesto, Mary E

    2014-06-01

    A laboratory study investigated the relationship between power hand tool and task-related factors affecting threaded fastener torque accuracy and associated handle reaction force. We previously developed a biodynamic model to predict handle reaction forces. We hypothesized that torque accuracy was related to the same factors that affect operator capacity to react against impulsive tool forces, as predicted by the model. The independent variables included tool (pistol grip on a vertical surface, right angle on a horizontal surface), fastener torque rate (hard, soft), horizontal distance (30 cm and 60 cm), and vertical distance (80 cm, 110 cm, and 140 cm). Ten participants (five male and five female) fastened 12 similar bolts for each experimental condition. Average torque error (audited - target torque) was affected by fastener torque rate and operator position. Torque error decreased 33% for soft torque rates, whereas handle forces greatly increased (170%). Torque error also decreased for the far horizontal distance 7% to 14%, when vertical distance was in the middle or high, but handle force decreased slightly 3% to 5%. The evidence suggests that although both tool and task factors affect fastening accuracy, they each influence handle reaction forces differently. We conclude that these differences are attributed to different parameters each factor influences affecting the dynamics of threaded faster tool operation. Fastener torque rate affects the tool dynamics, whereas posture affects the spring-mass-damping biodynamic properties of the human operator. The prediction of handle reaction force using an operator biodynamic model may be useful for codifying complex and unobvious relationships between tool and task factors for minimizing torque error while controlling handle force.

  10. Radiation reaction force and unification of electromagnetic and gravitational fields

    International Nuclear Information System (INIS)

    Lo, C.Y.; Goldstein, G.R.; Napier, A.

    1981-04-01

    A unified theory of electromagnetic and gravitational fields should modify classical electrodynamics such that the radiation reaction force is accounted for. The analysis leads to a five-dimensional unified theory of five variables. The theory is supported by showing that, for the case of a charged particle moving in a constant magnetic field, the radiation reaction force is indeed included. Moreover, this example shows explicitly that physical changes are associated with the fifth variable. Thus, the notion of a physical five-dimensional space should be seriously taken into consideration

  11. Vertical ground reaction forces in patients after calcaneal trauma surgery.

    Science.gov (United States)

    van Hoeve, S; Verbruggen, J; Willems, P; Meijer, K; Poeze, M

    2017-10-01

    Vertical ground reaction forces (VGRFs) are altered in patients after foot trauma. It is not known if this correlates with ankle kinematics. The aim of this study was to analyze VGRFs in patients after calcaneal trauma and correlate them to patient-reported outcome measures (PROMs), radiographic findings and kinematic analysis, using a multi-segment foot model. In addition, we determined the predictive value of VGRFs to identify patients with altered foot kinematics. Thirteen patients (13 feet) with displaced intra-articular calcaneal fractures, were included an average of two years after trauma surgery. PROMs, radiographic findings on postoperative computed tomography scans, gait analysis using the Oxford foot model and VGRFs were analysed during gait. Results were compared with those of 11 healthy subjects (20 feet). Speed was equal in both groups, with healthy subjects walking at self-selected slow speed (0.94±0.18m/s) and patients after surgery walking at self-selected normal speed (0.94±0.29m/s). ROC curves were used to determine the predictive value. Patients after calcaneal surgery showed a lower minimum force during midstance (p=0.004) and a lower maximum force during toe-off (p=0.011). This parameter correlated significantly with the range of motion in the sagittal plane during the push-off phase (r 0.523, p=0.002), as well as with PROMs and with postoperative residual step-off (r 0.423, p=0.016). Combining these two parameters yielded a cut-off value of 193% (ppush-off correlated significantly with PROMs, range of motion in the sagittal plane during push-off and radiographic postoperative residual step-off in the posterior facet of the calcaneal bone. VGRFs are a valuable screening tool for identifying patients with altered gait patterns. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Measuring Forces between Oxide Surfaces Using the Atomic Force Microscope

    DEFF Research Database (Denmark)

    Pedersen, Henrik Guldberg; Høj, Jakob Weiland

    1996-01-01

    The interactions between colloidal particles play a major role in processing of ceramics, especially in casting processes. With the Atomic Force Microscope (AFM) it is possible to measure the inter-action force between a small oxide particle (a few micron) and a surface as function of surface...

  13. Force measurements for levitated bulk superconductors

    International Nuclear Information System (INIS)

    Tachi, Y.; Sawa, K.; Iwasa, Y.; Nagashima, K.; Otani, T.; Miyamoto, T.; Tomita, M.; Murakami, M.

    2000-01-01

    We have developed a force measurement system which enables us to directly measure the levitation force of levitated bulk superconductors. Experimental data of the levitation forces were compared with the results of numerical simulation based on the levitation model that we deduced in our previous paper. They were in fairly good agreement, which confirms that our levitation model can be applied to the force analyses for levitated bulk superconductors. (author)

  14. Force measurements for levitated bulk superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Tachi, Y. [Department of Electrical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama (Japan); ISTEC, Superconductivity Research Laboratory, 1-16-25 Shibaura, Minato-ku, Tokyo (Japan). E-mail: tachi at istec.or.jp; Uemura, N. [Department of Electrical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama (Japan); ISTEC, Superconductivity Research Laboratory, 1-16-25 Shibaura, Minato-ku, Tokyo (Japan); Sawa, K. [Department of Electrical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama (Japan); Iwasa, Y. [Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA (United States); Nagashima, K. [Railway Technical Research Institute, Hikari-cho, Kokubunji-shi, Tokyo (Japan); Otani, T.; Miyamoto, T.; Tomita, M.; Murakami, M. [ISTEC, Superconductivity Research Laboratory, 1-16-25 Shibaura, Minato-ku, Tokyo (Japan)

    2000-06-01

    We have developed a force measurement system which enables us to directly measure the levitation force of levitated bulk superconductors. Experimental data of the levitation forces were compared with the results of numerical simulation based on the levitation model that we deduced in our previous paper. They were in fairly good agreement, which confirms that our levitation model can be applied to the force analyses for levitated bulk superconductors. (author)

  15. Forelimb and hindlimb ground reaction forces of walking cats: assessment and comparison with walking dogs.

    Science.gov (United States)

    Corbee, R J; Maas, H; Doornenbal, A; Hazewinkel, H A W

    2014-10-01

    The primary aim of this study was to assess the potential of force plate analysis for describing the stride cycle of the cat. The secondary aim was to define differences in feline and canine locomotion based on force plate characteristics. Ground reaction forces of 24 healthy cats were measured and compared with ground reaction forces of 24 healthy dogs. Force-time waveforms in cats generated by force plate analysis were consistent, as reflected by intra-class correlation coefficients for peak vertical force, peak propulsive force and peak braking force (0.94-0.95, 0.85-0.89 and 0.89-0.90, respectively). Compared with dogs, cats had a higher peak vertical force during the propulsion phase (cat, 3.89 ± 0.19 N/kg; dog, 3.03 ± 0.16 N/kg), and a higher hindlimb propulsive force (cat, -1.08 ± 0.13 N/kg; dog, (-0.87 ± 0.13 N/kg) and hindlimb impulse (cat, -0.18 ± 0.03 N/kg; dog, -0.14 ± 0.02 N/kg). Force plate analysis is a valuable tool for the assessment of locomotion in cats, because it can be applied in the clinical setting and provides a non-invasive and objective measurement of locomotion characteristics with high repeatability in cats, as well as information about kinetic characteristics. Differences in force-time waveforms between cats and dogs can be explained by the more crouched position of cats during stance and their more compliant gait compared with dogs. Feline waveforms of the medio-lateral ground reaction forces also differ between cats and dogs and this can be explained by differences in paw supination-pronation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Axial force measurement for esophageal function testing

    DEFF Research Database (Denmark)

    Gravesen, Flemming Holbæk; Funch-Jensen, Peter; Gregersen, Hans

    2009-01-01

    force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external...... force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been...... documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe...

  17. Ground Reaction Forces Generated During Rhythmical Squats as a Dynamic Loads of the Structure

    Science.gov (United States)

    Pantak, Marek

    2017-10-01

    Dynamic forces generated by moving persons can lead to excessive vibration of the long span, slender and lightweight structure such as floors, stairs, stadium stands and footbridges. These dynamic forces are generated during walking, running, jumping and rhythmical body swaying in vertical or horizontal direction etc. In the paper the mathematical models of the Ground Reaction Forces (GRFs) generated during squats have been presented. Elaborated models was compared to the GRFs measured during laboratory tests carried out by author in wide range of frequency using force platform. Moreover, the GRFs models were evaluated during dynamic numerical analyses and dynamic field tests of the exemplary structure (steel footbridge).

  18. Measurement of inertial confinement fusion reaction rate

    International Nuclear Information System (INIS)

    Peng Xiaoshi; Wang Feng; Tang Daorun; Liu Shenye; Huang Tianxuan; Liu Yonggang; Xu Tao; Chen Ming; Mei Yu

    2011-01-01

    Fusion reaction rate is an important parameter for measuring compression during the implosion in inertial confinement fusion experiment. We have developed a system for fusion reaction history measurement with high temporal resolution. The system is composed of plastic scintillator and nose cone, optical system and streak camera. We have applied this system on the SG-III prototype for fusion reaction rate measuring. For the first time, fusion reaction rate history have been measured for deuterium-tritium filled targets with neutrons yields about 10 10 . We have analyzed possible influence factor during fusion reaction rate measuring. It indicates that the instrument measures fusion reaction bang time at temporal resolutions as low as 30 ps.(authors)

  19. Measuring Air Force Contracting Customer Satisfaction

    Science.gov (United States)

    2015-12-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA MBA PROFESSIONAL REPORT MEASURING AIR FORCE CONTRACTING CUSTOMER SATISFACTION ...... satisfaction elements should be included in a standardized tool that measures the level of customer satisfaction for AF Contracting’s external and

  20. Anatomical kinematic constraints: consequences on muscular forces and joint reactions

    OpenAIRE

    MOISSENET, F; CHEZE, L; DUMAS, R

    2011-01-01

    This paper presents a method to determine musculo-tendon forces and joint reactions during gait, using a 3D right leg model with 5 DoFs: spherical joint at the hip and parallel mechanisms at both knee and ankle. A typical set of natural coordinates is used to obtain the dynamic equations. First, using a global optimization method, "anatomical" kinematic constraints (i.e., parallel mechanisms) are applied on the kinematics obtained from motion capture data. Consistent derivatives are computed ...

  1. One-dimensional central-force problem, including radiation reaction

    International Nuclear Information System (INIS)

    Kasher, J.C.

    1976-01-01

    Two equal masses of equal charge magnitude (either attractive or repulsive) are held a certain distance apart for their entire past history. AT t = 0 one of them is either started from rest or given an initial velocity toward or away from the other charge. When the Dirac radiation-reaction force is included in the force equation, our Taylor-series numerical calculations lead to two types of nonphysical results for both the attractive and repulsive cases. In the attractive case, the moving charge either stops and moves back out to infinity, or violates energy conservation as it nears collision with the fixed charge. For the repulsive charges, the moving particle either eventually approaches and collides with the fixed one, or violates energy conservation as it goes out to infinity. These results lead us to conclude that the Lorentz-Dirac equation is not valid for the one-dimensional central-force problem

  2. Pneumatic tool torque reaction: reaction forces, displacement, muscle activity and discomfort in the hand-arm system.

    Science.gov (United States)

    Kihlberg, S; Kjellberg, A; Lindbeck, L

    1993-06-01

    Reaction forces, hand-arm displacement, muscle activity and discomfort ratings were studied during the securing of threaded fasteners with three angle nutrunners with different shut-off mechanisms, but with the same spindle torque (72-74 Nm). The three tools were tested according to the method specified in ISO 6544. One of the tools had an almost instantaneous shut-off. Another had a more slowly declining torque curve. For the third tool the maximum torque was maintained for a while before shut-off. Twelve male subjects participated in the study. A force platform measured the reaction force between the subject and the floor. The option of the hand-arm system and the shoulder was measured with an optoelectronic measuring system. The muscle activity (EMG) in six muscles in the arm and shoulder was measured with surface electrodes. Significant differences in the arm movements and ground reaction forces were found between the three tools. The smallest values were found with the fast shut-off tool while the delayed shut-off tool caused the largest values. The EMG measures gave inconsistent response patterns. Discomfort ratings were highly correlated with the time for which the tool torque exceeded 90% of peak preset torque, but the time for which the tool torque exceeded 90% of peak calculated by the method specified in ISO 6544. Nutrunners with a shut-off mechanism that causes a slowly decreasing torque or a torque that is maintained for a while before shut-off should be avoided. If no substitutes are available, then a torque reaction bar should be mounted on the tool.

  3. Ground reaction forces of Olympic and World Championship race walkers.

    Science.gov (United States)

    Hanley, Brian; Bissas, Athanassios

    2016-01-01

    Race walking is an Olympic event where no visible loss of contact should occur and the knee must be straightened until midstance. The purpose of this study was to analyse ground reaction forces of world-class race walkers and associate them with key spatiotemporal variables. Nineteen athletes race walked along an indoor track and made contact with two force plates (1000 Hz) while being filmed using high-speed videography (100 Hz). Race walking speed was correlated with flight time (r = .46, p = .049) and flight distance (r = .69, p = .001). The knee's movement from hyperextension to flexion during late stance meant the vertical push-off force that followed midstance was smaller than the earlier loading peak (p push-off forces (r = .60, p = .011). Lower fluctuations in speed during stance were associated with higher stride frequencies (r = .69, p = .001), and highlighted the importance of avoiding too much braking in early stance. The flattened trajectory and consequential decrease in vertical propulsion might help the race walker avoid visible loss of contact (although non-visible flight times were useful in increasing stride length), while a narrow stride width was important in reducing peak forces in all three directions and could improve movement efficiency.

  4. Estimation of ground reaction forces and moments during gait using only inertial motion capture

    NARCIS (Netherlands)

    Karatsidis, Angelos; Bellusci, Giovanni; Schepers, H. Martin; de Zee, Mark; Andersen, Michael S.; Veltink, Petrus H.

    Ground reaction forces and moments (GRF&M) are important measures used as input in biomechanical analysis to estimate joint kinetics, which often are used to infer information for many musculoskeletal diseases. Their assessment is conventionally achieved using laboratory-based equipment that cannot

  5. Kinematic and ground reaction force accommodation during weighted walking.

    Science.gov (United States)

    James, C Roger; Atkins, Lee T; Yang, Hyung Suk; Dufek, Janet S; Bates, Barry T

    2015-12-01

    Weighted walking is a functional activity common in daily life and can influence risks for musculoskeletal loading, injury and falling. Much information exists about weighted walking during military, occupational and recreational tasks, but less is known about strategies used to accommodate to weight carriage typical in daily life. The purposes of the study were to examine the effects of weight carriage on kinematics and peak ground reaction force (GRF) during walking, and explore relationships between these variables. Twenty subjects walked on a treadmill while carrying 0, 44.5 and 89 N weights in front of the body. Peak GRF, sagittal plane joint/segment angular kinematics, stride length and center of mass (COM) vertical displacement were measured. Changes in peak GRF and displacement variables between weight conditions represented accommodation. Effects of weight carriage were tested using analysis of variance. Relationships between peak GRF and kinematic accommodation variables were examined using correlation and regression. Subjects were classified into sub-groups based on peak GRF responses and the correlation analysis was repeated. Weight carriage increased peak GRF by an amount greater than the weight carried, decreased stride length, increased vertical COM displacement, and resulted in a more extended and upright posture, with less hip and trunk displacement during weight acceptance. A GRF increase was associated with decreases in hip extension (|r|=.53, p=.020) and thigh anterior rotation (|r|=.57, p=.009) displacements, and an increase in foot anterior rotation displacement (|r|=.58, p=.008). Sub-group analysis revealed that greater GRF increases were associated with changes at multiple sites, while lesser GRF increases were associated with changes in foot and trunk displacement. Weight carriage affected walking kinematics and revealed different accommodation strategies that could have implications for loading and stability. Copyright © 2015 Elsevier B

  6. Normalized patellofemoral joint reaction force is greater in individuals with patellofemoral pain.

    Science.gov (United States)

    Thomeer, Lucas T; Sheehan, Frances T; Jackson, Jennifer N

    2017-07-26

    Patellofemoral pain is a disabling, highly prevalent pathology. Altered patellofemoral contact forces are theorized to contribute to this pain. Musculoskeletal modeling has been employed to better understand the etiology of patellofemoral pain. Currently, there are no data on the effective quadriceps moment arm for individuals with patellofemoral pain, forcing researchers to apply normative values when modeling such individuals. In addition, the ratio of patellofemoral reaction force to quadriceps force is often used as a surrogate for patellofemoral joint contact force, ignoring the fact that the quadriceps efficiency can vary with pathology and intervention. Thus, the purposes of this study were to: (1) quantify the effective quadriceps moment arm in individuals with patellofemoral pain and compare this value to a control cohort and (2) develop a novel methodology for quantifying the normalized patellofemoral joint reaction force in vivo during dynamic activities. Dynamic MR data were captured as subjects with patellofemoral pain (30F/3M) cyclically flexed their knee from 10° to 40°. Data for control subjects (29F/9M) were taken from a previous study. The moment arm data acquired across a large cohort of individuals with patellofemoral pain should help advance musculoskeletal modeling. The primary finding of this study was an increased mean normalized patellofemoral reaction force of 14.9% (maximum values at a knee angle of 10°) in individuals with patellofemoral pain. Understanding changes in the normalized patellofemoral reaction force with pathology may lead to improvements in clinical decision making, and consequently treatments, by providing a more direct measure of altered patellofemoral joint forces. Copyright © 2017. Published by Elsevier Ltd.

  7. Vertical ground reaction force analysis during gait with unstable shoes

    Directory of Open Access Journals (Sweden)

    Giulia Pereira

    Full Text Available AbstractIntroduction Footwear is no longer just an accessory but also a protection for the musculoskeletal system, and its most important characteristic is comfort.Objectives This study aims to identify and to analyze the vertical ground reaction force in barefoot women and women with unstable shoes.Methodology Five women aged 25 ± 4 years old and mass of 50 ± 7 kg participated in this study. An AMTI force plate was used for data acquisition. The 10 trials for each situation were considered valid where the subject approached the platform with the right foot and at the speed of 4 km/h ± 5%. The instable shoe of this study is used in the practice of physical activity.Results The results showed that the first peak force was higher for the footwear situation, about 5% and significant differences between the barefoot and footwear situation. This significant difference was in the first and second peaks force and in the time of the second peak.Conclusion The values showed that the footwear absorbs approximately 45% of the impact during gait.

  8. Forced thermal cycling of catalytic reactions: experiments and modelling

    DEFF Research Database (Denmark)

    Jensen, Søren; Olsen, Jakob Lind; Thorsteinsson, Sune

    2007-01-01

    Recent studies of catalytic reactions subjected to fast forced temperature oscillations have revealed a rate enhancement increasing with temperature oscillation frequency. We present detailed studies of the rate enhancement up to frequencies of 2.5 Hz. A maximum in the rate enhancement is observed...... at about 1 Hz. A model for the rate enhancement that includes the surface kinetics and the dynamic partial pressure variations in the reactor is introduced. The model predicts a levelling off of the rate enhancement with frequency at about 1 Hz. The experimentally observed decrease above 1 Hz is explained...

  9. The effects of dorso-lumbar motion restriction on the ground reaction force components during running.

    Science.gov (United States)

    Morley, Joseph J; Traum, Edward

    2016-04-01

    The effects of restricting dorso-lumbar spine mobility on ground reaction forces in runners was measured and assessed. A semi-rigid cast was used to restrict spinal motion during running. Subjects ran across a force platform at 3.6 m/s, planting the right foot on the platform. Data was collected from ten running trials with the cast and ten without the cast and analysed. Casted running showed that the initial vertical heel strike maximum was increased (p running (p running results in measurable and repeatable alterations in ground reaction force components. Alterations in load transfer due to decreased spinal motion may be a factor contributing to selected injuries in runners. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Detecting chameleons through Casimir force measurements

    International Nuclear Information System (INIS)

    Brax, Philippe; Bruck, Carsten van de; Davis, Anne-Christine; Shaw, Douglas; Mota, David F.

    2007-01-01

    The best laboratory constraints on strongly coupled chameleon fields come not from tests of gravity per se but from precision measurements of the Casimir force. The chameleonic force between two nearby bodies is more akin to a Casimir-like force than a gravitational one: The chameleon force behaves as an inverse power of the distance of separation between the surfaces of two bodies, just as the Casimir force does. Additionally, experimental tests of gravity often employ a thin metallic sheet to shield electrostatic forces; however, this sheet masks any detectable signal due to the presence of a strongly coupled chameleon field. As a result of this shielding, experiments that are designed to specifically test the behavior of gravity are often unable to place any constraint on chameleon fields with a strong coupling to matter. Casimir force measurements do not employ a physical electrostatic shield and as such are able to put tighter constraints on the properties of chameleons fields with a strong matter coupling than tests of gravity. Motivated by this, we perform a full investigation on the possibility of testing chameleon models with both present and future Casimir experiments. We find that present-day measurements are not able to detect the chameleon. However, future experiments have a strong possibility of detecting or rule out a whole class of chameleon models

  11. Measurement of tool forces in diamond turning

    Energy Technology Data Exchange (ETDEWEB)

    Drescher, J.; Dow, T.A.

    1988-12-01

    A dynamometer has been designed and built to measure forces in diamond turning. The design includes a 3-component, piezoelectric transducer. Initial experiments with this dynamometer system included verification of its predicted dynamic characteristics as well as a detailed study of cutting parameters. Many cutting experiments have been conducted on OFHC Copper and 6061-T6 Aluminum. Tests have involved investigation of velocity effects, and the effects of depth and feedrate on tool forces. Velocity has been determined to have negligible effects between 4 and 21 m/s. Forces generally increase with increasing depth of cut. Increasing feedrate does not necessarily lead to higher forces. Results suggest that a simple model may not be sufficient to describe the forces produced in the diamond turning process.

  12. Effects of Nordic walking and walking on spatiotemporal gait parameters and ground reaction force.

    Science.gov (United States)

    Park, Seung Kyu; Yang, Dae Jung; Kang, Yang Hun; Kim, Je Ho; Uhm, Yo Han; Lee, Yong Seon

    2015-09-01

    [Purpose] The purpose of this study was to investigate the effects of Nordic walking and walking on spatiotemporal gait parameters and ground reaction force. [Subjects] The subjects of this study were 30 young adult males, who were divided into a Nordic walking group of 15 subjects and a walking group of 15 subjects. [Methods] To analyze the spatiotemporal parameters and ground reaction force during walking in the two groups, the six-camera Vicon MX motion analysis system was used. The subjects were asked to walk 12 meters using the more comfortable walking method for them between Nordic walking and walking. After they walked 12 meters more than 10 times, their most natural walking patterns were chosen three times and analyzed. To determine the pole for Nordic walking, each subject's height was multiplied by 0.68. We then measured the spatiotemporal gait parameters and ground reaction force. [Results] Compared with the walking group, the Nordic walking group showed an increase in cadence, stride length, and step length, and a decrease in stride time, step time, and vertical ground reaction force. [Conclusion] The results of this study indicate that Nordic walking increases the stride and can be considered as helping patients with diseases affecting their gait. This demonstrates that Nordic walking is more effective in improving functional capabilities by promoting effective energy use and reducing the lower limb load, because the weight of the upper and lower limbs is dispersed during Nordic walking.

  13. Differences in pediatric vertical ground reaction force between planovalgus and neutrally aligned feet.

    Science.gov (United States)

    Pauk, Jolanta; Szymul, Joanna

    2014-01-01

    Ground reaction forces (GRF) reflect the force history of human body contact with the ground. The purpose of this study was to explore human gait abnormalities due to planovalgus by comparing vertical GRF data between individuals with planovalgus and those with neutrally aligned feet. Second we estimated associations between various measurements and vertical GRF parameters in a pediatric population. Boys and girls between the ages of 4 and 18 years (72 planovalgus feet and 74 neutrally aligned feet) took part in this study. Ground reaction forces were recorded by two Kistler platforms and normalized to body weight. Comparison of vertical GRF between planovalgus and neutrally aligned feet suggests that the first and the second peaks of vertical force (Fz1, Fz2) are most affected by planovalgus. The results also indicate that neutrally aligned feet display a different ground reaction force pattern than planovalgus, and that differences between boys and girls may be observed. The shape of the vertical GRF curve can help in clinical interpretation of abnormal gait.

  14. The Inertia Reaction Force and Its Vacuum Origin

    Science.gov (United States)

    Rueda, Alfonso; Haisch, Bernard

    By means of a covariant approach we show that there must be a contribution to the inertial mass and to the inertial reaction force on an accelerated massive object by the zero-point electromagnetic field. This development does not require any detailed model of the accelerated object other than the knowledge that it interacts electromagnetically. It is shown that inertia can indeed be construed as an opposition of the vacuum fields to any change to the uniform state of motion of an object. Interesting insights originating from this result are discussed. It is argued why the proposed existence of a Higgs field in no way contradicts or is at odds with the above statements. The Higgs field is responsible for assigning mass to elementary particles. It is argued that still the underlying reason for the opposition to acceleration that massive objects present requires an explanation. The explanation proposed here fulfills that requirement.

  15. Measuring pulsatile forces on the human cranium.

    Science.gov (United States)

    Goldberg, Cory S; Antonyshyn, Oleh; Midha, Rajiv; Fialkov, Jeffrey A

    2005-01-01

    The cyclic stresses in the cranium caused by pulsation of the brain play an important role in the design of materials for cranioplasty, as well as craniofacial development. However, these stresses have never been quantified. In this study, the force in the epidural space against the cranium was measured intraoperatively in 10 patients using a miniature force probe. Heart and ventilatory rates computed from the force tracing correlated closely with the corresponding measured values in the patients, confirming that the forces measured were indeed a result of brain pulsation. The mean outward systolic normal and tangential stresses were 54.2 kilo-Pascals (kPa) and 345.4 kPa, respectively. The systolic shear stress was 199.8 kPa. Through mechanotransduction, these stresses play a role in cranial development. The calculated yield stress of a cranioplasty repair was 0.4 MPa, which is within one order of magnitude of the known strength of common calcium-phosphate cements. This indicates a possible relation of these pulsatile forces and occult failure of calcium-phosphate cement cranioplasties through material fatigue.

  16. Unsteady Aerodynamic Force Sensing from Measured Strain

    Science.gov (United States)

    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

  17. A MEMS sensor for microscale force measurements

    International Nuclear Information System (INIS)

    Majcherek, S; Aman, A; Fochtmann, J

    2016-01-01

    This paper describes the development and testing of a new MEMS-based sensor device for microscale contact force measurements. A special MEMS cell was developed to reach higher lateral resolution than common steel-based load cells with foil-type strain gauges as mechanical-electrical converters. The design provided more than one normal force measurement point with spatial resolution in submillimeter range. Specific geometric adaption of the MEMS-device allowed adjustability of its measurement range between 0.5 and 5 N. The thin film nickel-chromium piezo resistors were used to achieve a mechanical-electrical conversion. The production process was realized by established silicon processing technologies such as deep reactive ion etching and vapor deposition (sputtering). The sensor was tested in two steps. Firstly, the sensor characteristics were carried out by application of defined loads at the measurement points by a push-pull tester. As a result, the sensor showed linear behavior. A measurement system analysis (MSA1) was performed to define the reliability of the measurement system. The measured force values had the maximal relative deviation of 1% to average value of 1.97 N. Secondly, the sensor was tested under near-industrial conditions. In this context, the thermal induced relaxation behavior of the electrical connector contact springs was investigated. The handling of emerging problems during the characterization process of the sensor is also described. (paper)

  18. Propellant Slosh Force and Mass Measurement

    Directory of Open Access Journals (Sweden)

    Andrew Hunt

    2018-01-01

    Full Text Available We have used electrical capacitance tomography (ECT to instrument a demonstration tank containing kerosene and have successfully demonstrated that ECT can, in real time, (i measure propellant mass to better than 1% of total in a range of gravity fields, (ii image propellant distribution, and (iii accurately track propellant centre of mass (CoM. We have shown that the ability to track CoM enables the determination of slosh forces, and we argue that this will result in disruptive changes in a propellant tank design and use in a spacecraft. Ground testing together with real-time slosh force data will allow an improved tank design to minimize and mitigate slosh forces, while at the same time keeping the tank mass to a minimum. Fully instrumented Smart Tanks will be able to provide force vector inputs to a spacecraft inertial navigation system; this in turn will (i eliminate or reduce navigational errors, (ii reduce wait time for uncertain slosh settling, since actual slosh forces will be known, and (iii simplify slosh control hardware, hence reducing overall mass. ECT may be well suited to space borne liquid measurement applications. Measurements are independent of and unaffected by orientation or levels of g. The electronics and sensor arrays can be low in mass, and critically, the technique does not dissipate heat into the propellant, which makes it intrinsically safe and suitable for cryogenic liquids. Because of the limitations of operating in earth-bound gravity, it has not been possible to check the exact numerical accuracy of the slosh force acting on the vessel. We are therefore in the process of undertaking a further project to (i build a prototype integrated “Smart Tank for Space”, (ii undertake slosh tests in zero or microgravity, (iii develop the system for commercial ground testing, and (iv qualify ECT for use in space.

  19. Memory effect o force measurements at nanoscales

    International Nuclear Information System (INIS)

    Lisy, V.; Tothova, J.

    2011-01-01

    we have obtained an exact solution for the drift velocity of a Brownian particle in an incompressible fluid under the action of a constant force, taking into account the hydrodynamic memory in the particle motion. This velocity is proportional to the applied force but depends in a complicated manner on the time of observation t. At short times it is proportional to t and at long times it contains algebraic tails, the longest-lived of which being ∼ t -1/ 2. Due to this the velocity very slowly approaches the limiting value F/γ. As a consequence, the force F can significantly differ from the value that would be extracted from the drift measurements neglecting the inertial effects, which is a standard assumption in the interpretation of such experiments. The presented method can be equally applicable in the case of force linearly depending on the particle position. For nonlinear forces, first the open question about the choice of convention to be used in stochastic calculus should be resolved. (authors)

  20. A COMPARISON OF UPPER-EXTREMITY REACTION FORCES BETWEEN THE YURCHENKO VAULT AND FLOOR EXERCISE

    Directory of Open Access Journals (Sweden)

    Matthew Kirk Seeley

    2005-06-01

    Full Text Available The purpose of this study was to examine reaction forces transmitted to the upper extremities of high-level gymnasts during the round-off phase of the Yurchenko vault. A secondary purpose of this study was to compare reaction forces during the Yurchenko vault to reaction forces observed in a tumbling pass during the floor exercise. Ten high-level, female gymnasts volunteered to participate. Conditions of the independent variable were the Yurchenko vault and floor exercise; dependent variables were peak vertical and peak anterior-posterior reaction forces. Each participant performed three trials of both conditions with the trail hand contacting a force platform. Vertical and anterior-posterior reaction forces, normalized to body weight, were greater (p < 0.05 during the round-off phase of the Yurchenko vault (2.38 than during the floor exercise round-off (2.15. Vertical reaction forces during the round-off phase of the Yurchenko vault and floor exercise round-off are similar to reaction forces transmitted to upper extremities during other gymnastic skills and ground reaction forces transmitted to lower extremities while running and walking at various speeds. Results of this study reveal a need for further research considering methods aimed at reducing reaction forces transmitted to the upper extremities during the Yurchenko vault and floor exercise.

  1. Estimation of Vertical Ground Reaction Forces and Sagittal Knee Kinematics During Running Using Three Inertial Sensors

    Directory of Open Access Journals (Sweden)

    Frank J. Wouda

    2018-03-01

    Full Text Available Analysis of running mechanics has traditionally been limited to a gait laboratory using either force plates or an instrumented treadmill in combination with a full-body optical motion capture system. With the introduction of inertial motion capture systems, it becomes possible to measure kinematics in any environment. However, kinetic information could not be provided with such technology. Furthermore, numerous body-worn sensors are required for a full-body motion analysis. The aim of this study is to examine the validity of a method to estimate sagittal knee joint angles and vertical ground reaction forces during running using an ambulatory minimal body-worn sensor setup. Two concatenated artificial neural networks were trained (using data from eight healthy subjects to estimate the kinematics and kinetics of the runners. The first artificial neural network maps the information (orientation and acceleration of three inertial sensors (placed at the lower legs and pelvis to lower-body joint angles. The estimated joint angles in combination with measured vertical accelerations are input to a second artificial neural network that estimates vertical ground reaction forces. To validate our approach, estimated joint angles were compared to both inertial and optical references, while kinetic output was compared to measured vertical ground reaction forces from an instrumented treadmill. Performance was evaluated using two scenarios: training and evaluating on a single subject and training on multiple subjects and evaluating on a different subject. The estimated kinematics and kinetics of most subjects show excellent agreement (ρ>0.99 with the reference, for single subject training. Knee flexion/extension angles are estimated with a mean RMSE <5°. Ground reaction forces are estimated with a mean RMSE < 0.27 BW. Additionaly, peak vertical ground reaction force, loading rate and maximal knee flexion during stance were compared, however, no significant

  2. Measurement-only topological quantum computation without forced measurements

    International Nuclear Information System (INIS)

    Zheng, Huaixiu; Dua, Arpit; Jiang, Liang

    2016-01-01

    We investigate the measurement-only topological quantum computation (MOTQC) approach proposed by Bonderson et al (2008 Phys. Rev. Lett. 101 010501) where the braiding operation is shown to be equivalent to a series of topological charge ‘forced measurements’ of anyons. In a forced measurement, the charge measurement is forced to yield the desired outcome (e.g. charge 0) via repeatedly measuring charges in different bases. This is a probabilistic process with a certain success probability for each trial. In practice, the number of measurements needed will vary from run to run. We show that such an uncertainty associated with forced measurements can be removed by simulating the braiding operation using a fixed number of three measurements supplemented by a correction operator. Furthermore, we demonstrate that in practice we can avoid applying the correction operator in hardware by implementing it in software. Our findings greatly simplify the MOTQC proposal and only require the capability of performing charge measurements to implement topologically protected transformations generated by braiding exchanges without physically moving anyons. (paper)

  3. A COMPARISON OF GROUND REACTION FORCES DETERMINED BY PORTABLE FORCE-PLATE AND PRESSURE-INSOLE SYSTEMS IN ALPINE SKIING

    Directory of Open Access Journals (Sweden)

    Kosuke Nakazato

    2011-12-01

    Full Text Available For the determination of ground reaction forces in alpine skiing, pressure insole (PI systems and portable force plate (FP systems are well known and widely used in previous studies. The purposes of this study were 1 to provide reference data for the vertical component of the ground reaction forces (vGRF during alpine skiing measured by the PI and FP systems, and 2 to analyze whether the differences in the vGRF measured by the PI and the FP depend on a skier's level, skiing mode and pitch. Ten expert and ten intermediate level skiers performed 10 double turns with the skiing technique "Carving in Short Radii" as High Dynamic Skiing mode and "Parallel Ski Steering in Long Radii" as Low Dynamic Skiing mode on both the steep (23 ° and the flat (15 ° slope twice. All subjects skied with both the PI and the FP system simultaneously. During the outside phase, the mean vGRF and the maximum vGRF determined by the FP are greater than the PI (p < 0.01. Additionally during the inside phase, the mean vGRF determined by the FP were greater than the PI (p < 0.01. During the edge changing phases, the mean vGRF determined by the FP were greater than the PI (p < 0.01. However, the minimum vGRF during the edge changing phases determined by the FP were smaller than the PI (p < 0.01 in the High-Steep skiing modes of Experts and Intermediates (p < 0.001. We have found that generally, the PI system underestimates the total vGRF compared to the FP system. However, this difference depends not only the phase in the turn (inside, outside, edge changing, but also is affected by the skier's level, the skiing mode performed and pitch.

  4. Ground reaction forces and knee kinetics during single and repeated badminton lunges.

    Science.gov (United States)

    Lam, Wing Kai; Ding, Rui; Qu, Yi

    2017-03-01

    Repeated movement (RM) lunge that frequently executed in badminton might be used for footwear evaluation. This study examined the influence of single movement (SM) and RM lunges on the ground reaction forces (GRFs) and knee kinetics during the braking phase of a badminton lunge step. Thirteen male university badminton players performed left-forward lunges in both SM and RM sessions. Force platform and motion capturing system were used to measure GRFs and knee kinetics variables. Paired t-test was performed to determine any significant differences between SM and RM lunges regarding mean and coefficient of variation (CV) in each variable. The kinetics results indicated that compared to SM lunges, the RM lunges had shorter contact time and generated smaller maximum loading rate of impact force, peak knee anterior-posterior force, and peak knee sagittal moment but generated larger peak horizontal resultant forces (Ps < 0.05). Additionally, the RM lunges had lower CV for peak knee medial-lateral and vertical forces (Ps < 0.05). These results suggested that the RM testing protocols had a distinct loading response and adaptation pattern during lunge and that the RM protocol showed higher within-trial reliability, which may be beneficial for the knee joint loading evaluation under different interventions.

  5. Near DC force measurement using PVDF sensors

    Science.gov (United States)

    Ramanathan, Arun Kumar; Headings, Leon M.; Dapino, Marcelo J.

    2018-03-01

    There is a need for high-performance force sensors capable of operating at frequencies near DC while producing a minimal mass penalty. Example application areas include steering wheel sensors, powertrain torque sensors, robotic arms, and minimally invasive surgery. The beta crystallographic phase polyvinylidene fluoride (PVDF) films are suitable for this purpose owing to their large piezoelectric constant. Unlike conventional capacitive sensors, beta crystallographic phase PVDF films exhibit a broad linear range and can potentially be designed to operate without complex electronics or signal processing. A fundamental challenge that prevents the implementation of PVDF in certain high-performance applications is their inability to measure static signals, which results from their first-order electrical impedance. Charge readout algorithms have been implemented which address this issue only partially, as they often require integration of the output signal to obtain the applied force profile, resulting in signal drift and signal processing complexities. In this paper, we propose a straightforward real time drift compensation strategy that is applicable to high output impedance PVDF films. This strategy makes it possible to utilize long sample times with a minimal loss of accuracy; our measurements show that the static output remains within 5% of the original value during half-hour measurements. The sensitivity and full-scale range are shown to be determined by the feedback capacitance of the charge amplifier. A linear model of the PVDF sensor system is developed and validated against experimental measurements, along with benchmark tests against a commercial load cell.

  6. Influences of Athletic Footwear on Ground Reaction Forces During A Sidestep Cutting Maneuver on Artificial Turf

    Directory of Open Access Journals (Sweden)

    Jacob R. Gdovin

    2018-04-01

    Full Text Available Background: Recreational athletes can select their desired footwear based on personal preferences of shoe properties such as comfort and weight. Commonly worn running shoes and cleated footwear with similar stud geometry and distribution are worn when performing sport-specific tasks such as a side-step cutting maneuver (SCM in soccer and American football (hereafter, referred to as football. The effects of such footwear on injury mechanics have been documented with less being known regarding their effect on performance. Objective: The purpose of this study was to examine performance differences including peak ground reaction forces (pGRF, time-to-peak ground reaction forces (tpGRF and the rate of force development (RFD between football cleats (FB, soccer cleats (SOC, and traditional running sneakers (RUN during the braking and propulsive phases of a SCM. Methodology: Eleven recreationally active males who participated in football and/or soccer-related activities at the time of testing completed the study. A 1 x 3 [1 Condition (SCM x 3 Footwear (RUN, FB, SOC] repeated measures ANOVA was utilized to analyze the aforementioned variables. Results: There were no significant differences (p > 0.05 between footwear conditions when comparing pGRF, tpGRF, or RFD in either the braking or propulsive phases. Conclusion: The results suggest that the studded and non-studded footwear allowed athletes to generate similar forces over a given time frame when performing a SCM.

  7. Quadriceps force and anterior tibial force occur obviously later than vertical ground reaction force: a simulation study

    OpenAIRE

    Ueno, Ryo; Ishida, Tomoya; Yamanaka, Masanori; Taniguchi, Shohei; Ikuta, Ryohei; Samukawa, Mina; Saito, Hiroshi; Tohyama, Harukazu

    2017-01-01

    Background: Although it is well known that quadriceps force generates anterior tibial force, it has been unclear whether quadriceps force causes great anterior tibial force during the early phase of a landing task. The purpose of the present study was to examine whether the quadriceps force induced great anterior tibial force during the early phase of a landing task. Methods: Fourteen young, healthy, female subjects performed a single-leg landing task. Muscle force and anterior tibial force w...

  8. Laboratory Measurements for H3+ Deuteration Reactions

    Science.gov (United States)

    Bowen, Kyle; Hillenbrand, Pierre-Michel; Urbain, Xavier; Savin, Daniel Wolf

    2018-06-01

    Deuterated molecules are important chemical tracers of protostellar cores. At the ~106 cm-3 particle densities and ~20 K temperatures typical for protostellar cores, most molecules freeze onto dust grains. A notable exception is H3+ and its isotopologues. These become important carriers of positive charge in the gas, can couple to any ambient magnetic field, and can thereby alter the cloud dynamics. Knowing the total abundance of H3+ and its isotopologues is important for studying the evolution of protostellar cores. However, H3+ and D3+ have no dipole moment. They lack a pure rotational spectrum and are not observable at protostellar core temperatures. Fortunately H2D+ and D2H+ have dipole moments and a pure rotational spectrum that can be excited in protostellar cores. Observations of these two molecules, combined with astrochemical models, provide information about the total abundance of H3+ and all its isotopologues. The inferred abundances, though, rely on accurate astrochemical data for the deuteration of H3+ and its isotopologues.Here we present laboratory measurements of the rate coefficients for three important deuterating reactions, namely D + H3+/H2D+/D2H+ → H + H2D+/ D2H+/D3+. Astrochemical models currently rely on rate coefficients from classical (Langevin) or semi-classical methods for these reactions, as fully quantum-mechanical calculations are beyond current computational capabilities. Laboratory studies are the most tractable means of providing the needed data. For our studies we used our novel dual-source, merged fast-beams apparatus, which enables us to study reactions of neutral atoms and molecular ions. Co-propagating beams allow us to measure experimental rate coefficients as a function of collision energy. We extract cross section data from these results, which we then convolve with a Maxwell-Boltzmann distribution to generate thermal rate coefficients. Here we present our results for these three reactions and discuss some implications.

  9. Use of SSNTD for measuring nuclear reactions

    Energy Technology Data Exchange (ETDEWEB)

    Bakr, M H [Division of Baic Nucl. Sc., NRC, Atomic Energy Authority Cairo (Egypt)

    1997-12-31

    Solid state nuclear track detectors (SSNTD) technique in nuclear reactions is reviewed. Special attention is given to the study of Makrofol-E films using a proposed optimum etching solution. The etching rate was 10.5 Mm/ hour. The energy resolution was measured and estimated to be 600 and 400 KeV in the energy ranges 1-2 MeV and 2-3 MeV respectively. Based on these results, the sensitivity threshold for gamma-particles in Makrofol-E is shifted up to 1 MeV, otherwise, there will be no discrimination between the etch - pits of gamma- particles with energies ranging from 0 to 1 MeV. The full angular distribution of the gamma-groups were measured in one run by means of a SSNTD sheel surrounding the target. A scattering chamber designed for gamma-particle angular distribution measurements is described. An example of the influence of energy loss in degrading Al foils in eliminating the energy angle dependence is given. The numerous curves of the range -energy dependence of gamma - particles in Makrofol - E after passing Al foils of different thicknesses are scaled in one schematic normograph. The later simplifies the process of choosing the suitable Al foil thickness or of determining the range- energy relation. The angular distributions of five gamma- groups from the {sup 56} Co (P, gamma) {sup 56} Fe reaction in the proton energy 1.6 -2.4 MeV have been measured using the designed chamber. A Makrofol - E film of 200 Mm thickness was exposed to the reaction products for 5 hours. This time was enough to get the angular distribution for (d/d) in the range 5-72 Mm barn/ster.

  10. Isokinetic analysis of ankle and ground reaction forces in runners and triathletes

    Directory of Open Access Journals (Sweden)

    Natália Mariana Silva Luna

    2012-09-01

    Full Text Available OBJECTIVE: To analyze and compare the vertical component of ground reaction forces and isokinetic muscle parameters for plantar flexion and dorsiflexion of the ankle between long-distance runners, triathletes, and nonathletes. METHODS: Seventy-five males with a mean age of 30.26 (±6.5 years were divided into three groups: a triathlete group (n=26, a long-distance runner group (n = 23, and a non-athlete control group. The kinetic parameters were measured during running using a force platform, and the isokinetic parameters were measured using an isokinetic dynamometer. RESULTS: The non-athlete control group and the triathlete group exhibited smaller vertical forces, a greater ground contact time, and a greater application of force during maximum vertical acceleration than the long-distance runner group. The total work (180º/s was greater in eccentric dorsiflexion and concentric plantar flexion for the non-athlete control group and the triathlete group than the long-distance runner group. The peak torque (60º/s was greater in eccentric plantar flexion and concentric dorsiflexion for the control group than the athlete groups. CONCLUSIONS: The athlete groups exhibited less muscle strength and resistance than the control group, and the triathletes exhibited less impact and better endurance performance than the runners.

  11. Squeezed noise in precision force measurements

    International Nuclear Information System (INIS)

    Bocko, M.F.; Bordoni, F.; Fuligni, F.; Johnson, W.W.

    1986-01-01

    The effort to build gravitational radiation antennae with sensitivity sufficient to detect bursts of radiation from supernovae in the Virgo cluster of galaxies has caused a consideration of the fundamental limits for the detection of weak forces. The existing Weber bar detectors will be eventually limited, by the phase insensitive transducers now used, to noise temperatures no better than that of the first amplifier which follows the transducer. Even for a quantum limited amplifier this may not give the sensitivity required to definitively detect gravitational radiation. In a 'back action evasion' measurement a specific phase sensitive transducer would be used. It is believed that by the technique of measuring one of the two antenna phases it is possible to reach an effective noise temperature for the measured phase which is far below the amplifier noise temperature. This is at the expense of an infinite noise temperature in the unmeasured antenna phase and is thus described as squeezing the noise. The authors outline the theoretical model for the behavior of such systems and present data from several experiments which demonstrate the main features of a back action evasion measurement. (Auth.)

  12. Biomechanics of gecko locomotion: the patterns of reaction forces on inverted, vertical and horizontal substrates

    International Nuclear Information System (INIS)

    Wang, Zhouyi; Dai, Zhendong; Ji, Aihong; Xing, Qiang; Ren, Lei; Dai, Liming

    2015-01-01

    The excellent locomotion ability of geckos on various rough and/or inclined substrates has attracted scientists’ attention for centuries. However, the moving ability of gecko-mimicking robots on various inclined surfaces still lags far behind that of geckos, mainly because our understanding of how geckos govern their locomotion is still very poor. To reveal the fundamental mechanism of gecko locomotion and also to facilitate the design of gecko-mimicking robots, we have measured the reaction forces (RFs) acting on each individual foot of moving geckos on inverted, vertical and horizontal substrates (i.e. ceiling, wall and floor), have associated the RFs with locomotion behaviors by using high-speed camera, and have presented the relationships of the force components with patterns of reaction forces (PRFs). Geckos generate different PRF on ceiling, wall and floor, that is, the PRF is determined by the angles between the direction of gravity and the substrate on which geckos move. On the ceiling, geckos produce reversed shear forces acting on the front and hind feet, which pull away from the body in both lateral and fore-aft directions. They use a very large supporting angle from 21° to 24° to reduce the forces acting on their legs and feet. On the floor, geckos lift their bodies using a supporting angle from 76° to 78°, which not only decreases the RFs but also improves their locomotion ability. On the wall, geckos generate a reliable self-locking attachment by using a supporting angle of 14.8°, which is only about half of the critical angle of detachment. (paper)

  13. Void Measurement by the ({gamma}, n) Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Rouhani, S Zia

    1962-09-15

    It is proposed to use the ({gamma}, n) reaction for the measurement of the integrated void volume fraction in two phase flow of D{sub 2}O inside a duct. This method is applicable to different channel geometries, and it is shown to be insensitive to the pattern of void distribution over the cross-sectional area of the channels The method has been tested on mock-ups of voids in a round duct of 6 mm inside diameter. About 40 m.c. {sup 24}Na was used as a source of gamma-rays. The test results show that the maximum measured error in this arrangement is less than 2.5 % (net void) for a range of 2.7 % to 44.44 % actual void volume fractions.

  14. Void Measurement by the (γ, n) Reaction

    International Nuclear Information System (INIS)

    Rouhani, S. Zia

    1962-09-01

    It is proposed to use the (γ, n) reaction for the measurement of the integrated void volume fraction in two phase flow of D 2 O inside a duct. This method is applicable to different channel geometries, and it is shown to be insensitive to the pattern of void distribution over the cross-sectional area of the channels The method has been tested on mock-ups of voids in a round duct of 6 mm inside diameter. About 40 m.c. 24 Na was used as a source of gamma-rays. The test results show that the maximum measured error in this arrangement is less than 2.5 % (net void) for a range of 2.7 % to 44.44 % actual void volume fractions

  15. The Comparison of Vertical Ground Reaction Force during Forward and Backward Walking among Professional Male Karatekas with Genu Varum and Normal Knees

    OpenAIRE

    Heydar Sadeghi; Siavash Shirvanipour; Raghad Mimar

    2017-01-01

    Objective: The purpose of this study was to compare vertical ground reaction force during forward and backward walking among the male professional Karatekas with genu varum and normal knee. Methods: 20 professional male Karates (in genu varum and normal groups) participated in this semi-experimental study. The vertical ground reaction force was measured using force plate system during forward and backward walking utilizing 250 Hz frequency. Mixed ANOVA test was run to analyze the obtained ...

  16. Force-induced chemical reactions on the metal centre in a single metalloprotein molecule

    Science.gov (United States)

    Zheng, Peng; Arantes, Guilherme M.; Field, Martin J.; Li, Hongbin

    2015-01-01

    Metalloproteins play indispensable roles in biology owing to the versatile chemical reactivity of metal centres. However, studying their reactivity in many metalloproteins is challenging, as protein three-dimensional structure encloses labile metal centres, thus limiting their access to reactants and impeding direct measurements. Here we demonstrate the use of single-molecule atomic force microscopy to induce partial unfolding to expose metal centres in metalloproteins to aqueous solution, thus allowing for studying their chemical reactivity in aqueous solution for the first time. As a proof-of-principle, we demonstrate two chemical reactions for the FeS4 centre in rubredoxin: electrophilic protonation and nucleophilic ligand substitution. Our results show that protonation and ligand substitution result in mechanical destabilization of the FeS4 centre. Quantum chemical calculations corroborated experimental results and revealed detailed reaction mechanisms. We anticipate that this novel approach will provide insights into chemical reactivity of metal centres in metalloproteins under biologically more relevant conditions. PMID:26108369

  17. Relationships Between Countermovement Jump Ground Reaction Forces and Jump Height, Reactive Strength Index, and Jump Time.

    Science.gov (United States)

    Barker, Leland A; Harry, John R; Mercer, John A

    2018-01-01

    Barker, LA, Harry, JR, and Mercer, JA. Relationships between countermovement jump ground reaction forces and jump height, reactive strength index, and jump time. J Strength Cond Res 32(1): 248-254, 2018-The purpose of this study was to determine the relationship between ground reaction force (GRF) variables to jump height, jump time, and the reactive strength index (RSI). Twenty-six, Division-I, male, soccer players performed 3 maximum effort countermovement jumps (CMJs) on a dual-force platform system that measured 3-dimensional kinetic data. The trial producing peak jump height was used for analysis. Vertical GRF (Fz) variables were divided into unloading, eccentric, amortization, and concentric phases and correlated with jump height, RSI (RSI = jump height/jump time), and jump time (from start to takeoff). Significant correlations were observed between jump height and RSI, concentric kinetic energy, peak power, concentric work, and concentric displacement. Significant correlations were observed between RSI and jump time, peak power, unload Fz, eccentric work, eccentric rate of force development (RFD), amortization Fz, amortization time, second Fz peak, average concentric Fz, and concentric displacement. Significant correlations were observed between jump time and unload Fz, eccentric work, eccentric RFD, amortization Fz, amortization time, average concentric Fz, and concentric work. In conclusion, jump height correlated with variables derived from the concentric phase only (work, power, and displacement), whereas Fz variables from the unloading, eccentric, amortization, and concentric phases correlated highly with RSI and jump time. These observations demonstrate the importance of countermovement Fz characteristics for time-sensitive CMJ performance measures. Researchers and practitioners should include RSI and jump time with jump height to improve their assessment of jump performance.

  18. How do the substrate reaction forces acting on a gecko's limbs respond to inclines?

    Science.gov (United States)

    Wang, Zhouyi; Dai, Zhendong; Li, Wei; Ji, Aihong; Wang, Wenbao

    2015-02-01

    Locomotion is an essential character of animals, and excellent moving ability results from the delicate sensing of the substrate reaction forces (SRF) acting on body and modulating the behavior to adapt the motion requirement. The inclined substrates present in habitats pose a number of functional challenges to locomotion. In order to effectively overcome these challenges, climbing geckos execute complex and accurate movements that involve both the front and hind limbs. Few studies have examined gecko's SRF on steeper inclines of greater than 90°. To reveal how the SRFs acting on the front and hind limbs respond to angle incline changes, we obtained detailed measurements of the three-dimensional SRFs acting on the individual limbs of the tokay gecko while it climbed on an inclined angle of 0-180°. The fore-aft forces acting on the front and hind limbs show opposite trends on inverted inclines of greater than 120°, indicating propulsion mechanism changes in response to inclines. When the incline angles change, the forces exerted in the normal and fore-aft directions by gecko's front and hind limbs are reassigned to take full advantage of limbs' different roles in overcoming resistance and in propelling locomotion. This also ensures that weight acts in the angle range between the forces generated by the front and hind limbs. The change in the distribution of SRF with a change in the incline angle is directly linked to the favorable trade-off between locomotive maneuverability and stability.

  19. Development of a commercially viable piezoelectric force sensor system for static force measurement

    Science.gov (United States)

    Liu, Jun; Luo, Xinwei; Liu, Jingcheng; Li, Min; Qin, Lan

    2017-09-01

    A compensation method for measuring static force with a commercial piezoelectric force sensor is proposed to disprove the theory that piezoelectric sensors and generators can only operate under dynamic force. After studying the model of the piezoelectric force sensor measurement system, the principle of static force measurement using a piezoelectric material or piezoelectric force sensor is analyzed. Then, the distribution law of the decay time constant of the measurement system and the variation law of the measurement system’s output are studied, and a compensation method based on the time interval threshold Δ t and attenuation threshold Δ {{u}th} is proposed. By calibrating the system and considering the influences of the environment and the hardware, a suitable Δ {{u}th} value is determined, and the system’s output attenuation is compensated based on the Δ {{u}th} value to realize the measurement. Finally, a static force measurement system with a piezoelectric force sensor is developed based on the compensation method. The experimental results confirm the successful development of a simple compensation method for static force measurement with a commercial piezoelectric force sensor. In addition, it is established that, contrary to the current perception, a piezoelectric force sensor system can be used to measure static force through further calibration.

  20. Measurement of dynamic bite force during mastication.

    Science.gov (United States)

    Shimada, A; Yamabe, Y; Torisu, T; Baad-Hansen, L; Murata, H; Svensson, P

    2012-05-01

    Efficient mastication of different types and size of food depends on fast integration of sensory information from mechanoreceptors and central control mechanisms of jaw movements and applied bite force. The neural basis underlying mastication has been studied for decades but little progress in understanding the dynamics of bite force has been made mainly due to technical limitations of bite force recorders. The aims of this study were to develop a new intraoral bite force recorder which would allow the study of natural mastication without an increase in the occlusal vertical dimension and subsequently to analyze the relation between electromyographic (EMG) activity of jaw-closing muscles, jaw movements and bite force during mastication of five different types of food. Customized force recorders based on strain gauge sensors were fitted to the upper and lower molar teeth on the preferred chewing side in fourteen healthy and dentate subjects (21-39 years), and recordings were carried out during voluntary mastication of five different kinds of food. Intraoral force recordings were successively obtained from all subjects. anova showed that impulse of bite force as well as integrated EMG was significantly influenced by food (Pmastication with direct implications for oral rehabilitation. We also propose that the control of bite force during mastication is achieved by anticipatory adjustment and encoding of bolus characteristics. © 2012 Blackwell Publishing Ltd.

  1. Neutron spectrum measurement in D + Be reaction

    CERN Document Server

    Abbasi-Davani, F; Aslani, G R; Etaati, G R; Koohi-Fayegh, R

    2002-01-01

    In this project the neutron spectra from the reaction of deuteron on beryllium nuclei is measured. The energies of deuterons were 7, 10, 13 and 15 MeV, and these measurements are performed at 10,30 and 50 degrees relative to the beam of deuterons. The detector used is 76 by 76 mm right circular cylinder of N E-213 liquid scintillator. The zero crossing technique is used for gamma discrimination. For the elimination of the background radiation, a Polyethylene block, 40 cm in thickness, with inserted cadmium sheets, and a lead block, 5 cm in thickness, were used. In order to obtain the background radiation spectrum, the latter blocks were placed between the target and the detector to eliminate neutron and gamma radiations reaching the detector directly. sup F ORIST sup c ode is used to unfold the neutron spectra from the measured pulse high t spectra and sup O 5S sup a nd sup R ESPMG sup c odes are used to obtain the detector response matrix.

  2. Effect of gender, cadence, and water immersion on ground reaction forces during stationary running.

    Science.gov (United States)

    de Brito Fontana, Heiliane; Haupenthal, Alessandro; Ruschel, Caroline; Hubert, Marcel; Ridehalgh, Colette; Roesler, Helio

    2012-05-01

    Controlled laboratory study. To analyze the vertical and anteroposterior components of the ground reaction force during stationary running performed in water and on dry land, focusing on the effect of gender, level of immersion, and cadence. Stationary running, as a fundamental component of aquatic rehabilitation and training protocols, is little explored in the literature with regard to biomechanical variables, which makes it difficult to determine and control the mechanical load acting on the individuals. Twenty-two subjects performed 1 minute of stationary running on land, immersed to the hip, and immersed to the chest at 3 different cadences: 90 steps per minute, 110 steps per minute, and 130 steps per minute. Force data were acquired with a force plate, and the variables were vertical peak (Fy), loading rate (LR), anterior peak (Fx anterior), and posterior peak (Fx posterior). Data were normalized to subjects' body weight (BW) and analyzed using repeated-measures analysis of variance. Fy ranged from 0.98 to 2.11 BW, LR ranged from 5.38 to 11.52 BW/s, Fx anterior ranged from 0.07 to 0.14 BW, and Fx posterior ranged from 0.06 to 0.09 BW. The gender factor had no effect on the variables analyzed. A significant interaction between level of immersion and cadence was observed for Fy, Fx anterior, and Fx posterior. On dry land, Fy increased with increasing cadence, whereas in water this effect was seen only between 90 steps per minute and the 2 higher cadences. The higher the level of immersion, the lower the magnitude of Fy. LR was reduced under both water conditions and increased with increasing cadence, regardless of the level of immersion. Ground reaction forces during stationary running are similar between genders. Fy and LR are lower in water, though the values are increased at higher cadences.

  3. Cantilevers orthodontics forces measured by fiber sensors

    Science.gov (United States)

    Schneider, Neblyssa; Milczewski, Maura S.; de Oliveira, Valmir; Guariza Filho, Odilon; Lopes, Stephani C. P. S.; Kalinowski, Hypolito J.

    2015-09-01

    Fibers Bragg Gratings were used to evaluate the transmission of the forces generates by orthodontic mechanic based one and two cantilevers used to move molars to the upright position. The results showed levels forces of approximately 0,14N near to the root of the molar with one and two cantilevers.

  4. Step-to-step spatiotemporal variables and ground reaction forces of intra-individual fastest sprinting in a single session.

    Science.gov (United States)

    Nagahara, Ryu; Mizutani, Mirai; Matsuo, Akifumi; Kanehisa, Hiroaki; Fukunaga, Tetsuo

    2018-06-01

    We aimed to investigate the step-to-step spatiotemporal variables and ground reaction forces during the acceleration phase for characterising intra-individual fastest sprinting within a single session. Step-to-step spatiotemporal variables and ground reaction forces produced by 15 male athletes were measured over a 50-m distance during repeated (three to five) 60-m sprints using a long force platform system. Differences in measured variables between the fastest and slowest trials were examined at each step until the 22nd step using a magnitude-based inferences approach. There were possibly-most likely higher running speed and step frequency (2nd to 22nd steps) and shorter support time (all steps) in the fastest trial than in the slowest trial. Moreover, for the fastest trial there were likely-very likely greater mean propulsive force during the initial four steps and possibly-very likely larger mean net anterior-posterior force until the 17th step. The current results demonstrate that better sprinting performance within a single session is probably achieved by 1) a high step frequency (except the initial step) with short support time at all steps, 2) exerting a greater mean propulsive force during initial acceleration, and 3) producing a greater mean net anterior-posterior force during initial and middle acceleration.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    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 µ m  ×  15 µ m  ×  5 µ m 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 µ N, respectively. The cell traction force was measured, and the traction force increased by approximately 1 µ N over 30 min. These results demonstrate that the proposed force plate is applicable as an effective traction force measurement. (paper)

  6. Exploring Reaction Mechanism on Generalized Force Modified Potential Energy Surfaces (G-FMPES) for Diels-Alder Reaction

    Science.gov (United States)

    Jha, Sanjiv; Brown, Katie; Subramanian, Gopinath

    We apply a recent formulation for searching minimum energy reaction path (MERP) and saddle point to atomic systems subjected to an external force. We demonstrate the effect of a loading modality resembling hydrostatic pressure on the trans to cis conformational change of 1,3-butadiene, and the simplest Diels-Alder reaction between ethylene and 1,3-butadiene. The calculated MERP and saddle points on the generalized force modified potential energy surface (G-FMPES) are compared with the corresponding quantities on an unmodified potential energy surface. Our study is performed using electronic structure calculations at the HF/6-31G** level as implemented in the AIMS-MOLPRO code. Our calculations suggest that the added compressive pressure lowers the energy of cis butadiene. The activation energy barrier for the concerted Diels-Alder reaction is found to decrease progressively with increasing compressive pressure.

  7. The influence of cricket fast bowlers' front leg technique on peak ground reaction forces.

    Science.gov (United States)

    Worthington, Peter; King, Mark; Ranson, Craig

    2013-01-01

    High ground reaction forces during the front foot contact phase of the bowling action are believed to be a major contributor to the high prevalence of lumbar stress fractures in fast bowlers. This study aimed to investigate the influence of front leg technique on peak ground reaction forces during the delivery stride. Three-dimensional kinematic data and ground reaction forces during the front foot contact phase were captured for 20 elite male fast bowlers. Eight kinematic parameters were determined for each performance, describing run-up speed and front leg technique, in addition to peak force and time to peak force in the vertical and horizontal directions. There were substantial variations between bowlers in both peak forces (vertical 6.7 ± 1.4 body weights; horizontal (braking) 4.5 ± 0.8 body weights) and times to peak force (vertical 0.03 ± 0.01 s; horizontal 0.03 ± 0.01 s). These differences were found to be linked to the orientation of the front leg at the instant of front foot contact. In particular, a larger plant angle and a heel strike technique were associated with lower peak forces and longer times to peak force during the front foot contact phase, which may help reduce the likelihood of lower back injuries.

  8. Assessment of changes in gait parameters and vertical ground reaction forces after total hip arthroplasty

    Directory of Open Access Journals (Sweden)

    Bhargava P

    2007-01-01

    Full Text Available The principal objectives of arthroplasty are relief of pain and enhancement of range of motion. Currently, postoperative pain and functional capacity are assessed largely on the basis of subjective evaluation scores. Because of the lack of control inherent in this method it is often difficult to interpret data presented by different observers in the critical evaluation of surgical method, new components and modes of rehabilitation. Gait analysis is a rapid, simple and reliable method to assess functional outcome. This study was undertaken in an effort to evaluate the gait characteristics of patients who underwent arthroplasty, using an Ultraflex gait analyzer. Materials and Methods: The study was based on the assessment of gait and weight-bearing pattern of both hips in patients who underwent total hip replacement and its comparison with an age and sex-matched control group. Twenty subjects of total arthroplasty group having unilateral involvement, operated by posterior approach at our institution with a minimum six-month postoperative period were selected. Control group was age and sex-matched, randomly selected from the general population. Gait analysis was done using Ultraflex gait analyzer. Gait parameters and vertical ground reaction forces assessment was done by measuring the gait cycle properties, step time parameters and VGRF variables. Data of affected limb was compared with unaffected limb as well as control group to assess the weight-bearing pattern. Statistical analysis was done by′t′ test. Results: Frequency is reduced and gait cycle duration increased in total arthroplasty group as compared with control. Step time parameters including Step time, Stance time and Single support time are significantly reduced ( P value < .05 while Double support time and Single swing time are significantly increased ( P value < .05 in the THR group. Forces over each sensor are increased more on the unaffected limb of the THR group as compared to

  9. Measuring Agglomeration Forces in a Financial Center

    OpenAIRE

    Bourgain, Arnaud; Pieretti, Patrice

    2006-01-01

    Basing on Scitovsky's (1954) definition of external economies and applying the method of Caballero and Lyons (1990) to macro data of Luxembourg services industry, we find significant agglomeration forces between financial intermediaries (downstream industry) on the one hand and business services and computer industry (upstream industries) on the other.

  10. Measurement and prediction of cutting forces and vibrations on longwall shearers

    Energy Technology Data Exchange (ETDEWEB)

    Bulent Tiryaki [CRCMining (Australia)

    2006-12-15

    CRCMining has developed the Cutting Head Performance Analysis Software (CPAS) to predict cutter motor power, ranging arm reaction forces, and vibrations for different drum designs, coal seams, and shearer operational conditions. This project describes the work on THE DBT EL3000 shearer at Beltana to validate/update CPAS by measuring the cutter motor power, ranging arm vibrations, and reaction forces through an online data acquisition system called Cutting Head Performance Monitoring System (CPMS). This system records the outputs of six strain gauge bridges, six accelerometers, and two pressure transducers on ranging arms during underground coal production. CPAS2 has then been developed in order to eliminate the needs for performing coal cutting tests for the target coal seam. CPAS2 simulations for cutter motor power, vertical reaction force, and vibrations were also close to those measured in the trials. CRCMining will release the CPAS code including fully functioning software code on CD to Australian coal mining industry.

  11. Ground reaction forces and bone parameters in females with tibial stress fracture.

    Science.gov (United States)

    Bennell, Kim; Crossley, Kay; Jayarajan, Jyotsna; Walton, Elizabeth; Warden, Stuart; Kiss, Z Stephen; Wrigley, Tim

    2004-03-01

    Tibial stress fracture is a common overuse running injury that results from the interplay of repetitive mechanical loading and bone strength. This research project aimed to determine whether female runners with a history of tibial stress fracture (TSF) differ in ground reaction force (GRF) parameters during running, regional bone density, and tibial bone geometry from those who have never sustained a stress fracture (NSF). Thirty-six female running athletes (13 TSF; 23 NSF) ranging in age from 18 to 44 yr were recruited for this cross-sectional study. The groups were well matched for demographic, training, and menstrual parameters. A force platform measured selected GRF parameters (peak and time to peak for vertical impact and active forces, and horizontal braking and propulsive forces) during overground running at 4.0 m.s.(-1). Lumbar spine, proximal femur, and distal tibial bone mineral density were assessed by dual energy x-ray absorptiometry. Tibial bone geometry (cross-sectional dimensions and areas, and second moments of area) was calculated from a computerized tomography scan at the junction of the middle and distal thirds. There were no significant differences between the groups for any of the GRF, bone density, or tibial bone geometric parameters (P > 0.05). Both TSF and NSF subjects had bone density levels that were average or above average compared with a young adult reference range. Factor analysis followed by discriminant function analysis did not find any combinations of variables that differentiated between TSF and NSF groups. These findings do not support a role for GRF, bone density, or tibial bone geometry in the development of tibial stress fractures, suggesting that other risk factors were more important in this cohort of female runners.

  12. Ground reaction forces produced by two different hockey skating arm swing techniques.

    Science.gov (United States)

    Hayward-Ellis, Julie; Alexander, Marion J L; Glazebrook, Cheryl M; Leiter, Jeff

    2017-10-01

    The arm swing in hockey skating can have a positive effect on the forces produced by each skate, and the resulting velocity from each push off. The main purpose of this study was to measure the differences in ground reaction forces (GRFs) produced from an anteroposterior versus a mediolateral style hockey skating arm swing. Twenty-four elite-level female hockey players performed each technique while standing on a ground-mounted force platform, and all trials were filmed using two video cameras. Force data was assessed for peak scaled GRFs in the frontal and sagittal planes, and resultant GRF magnitude and direction. Upper limb kinematics were assessed from the video using Dartfish video analysis software, confirming that the subjects successfully performed two distinct arm swing techniques. The mediolateral arm swing used a mean of 18.38° of glenohumeral flexion/extension and 183.68° of glenohumeral abduction/adduction while the anteroposterior technique used 214.17° and 28.97° respectively. The results of this study confirmed that the mediolateral arm swing produced 37% greater frontal plane and 33% less sagittal plane GRFs than the anteroposterior arm swing. The magnitudes of the resultant GRFs were not significantly different between the two techniques; however, the mediolateral technique produced a resultant GRF with a significantly larger angle from the direction of travel (44.44°) as compared to the anteroposterior technique (31.60°). The results of this study suggest that the direction of GRFs produced by the mediolateral arm swing more closely mimic the direction of lower limb propulsion during the skating stride.

  13. BILATERAL GROUND REACTION FORCES AND JOINT MOMENTS FOR LATERAL SIDESTEPPING AND CROSSOVER STEPPING TASKS

    Directory of Open Access Journals (Sweden)

    William I. Sellers

    2009-03-01

    Full Text Available Racquet sports have high levels of joint injuries suggesting the joint loads during play may be excessive. Sports such as badminton employ lateral sidestepping (SS and crossover stepping (XS movements which so far have not been described in terms of biomechanics. This study examined bilateral ground reaction forces and three dimensional joint kinetics for both these gaits in order to determine the demands of the movements on the leading and trailing limb and predict the contribution of these movements to the occurrence of overuse injury of the lower limbs. A force platform and motion-analysis system were used to record ground reaction forces and track marker trajectories of 9 experienced male badminton players performing lateral SS, XS and forward running tasks at a controlled speed of 3 m·s-1 using their normal technique. Ground reaction force and kinetic data for the hip, knee and ankle were analyzed, averaged across the group and the biomechanical variables compared. In all cases the ground reaction forces and joint moments were less than those experienced during moderate running suggesting that in normal play SS and XS gaits do not lead to high forces that could contribute to increased injury risk. Ground reaction forces during SS and XS do not appear to contribute to the development of overuse injury. The distinct roles of the leading and trailing limb, acting as a generator of vertical force and shock absorber respectively, during the SS and XS may however contribute to the development of muscular imbalances which may ultimately contribute to the development of overuse injury. However it is still possible that faulty use of these gaits might lead to high loads and this should be the subject of future work

  14. A rolling constraint reproduces ground reaction forces and moments in dynamic simulations of walking, running, and crouch gait.

    Science.gov (United States)

    Hamner, Samuel R; Seth, Ajay; Steele, Katherine M; Delp, Scott L

    2013-06-21

    Recent advances in computational technology have dramatically increased the use of muscle-driven simulation to study accelerations produced by muscles during gait. Accelerations computed from muscle-driven simulations are sensitive to the model used to represent contact between the foot and ground. A foot-ground contact model must be able to calculate ground reaction forces and moments that are consistent with experimentally measured ground reaction forces and moments. We show here that a rolling constraint can model foot-ground contact and reproduce measured ground reaction forces and moments in an induced acceleration analysis of muscle-driven simulations of walking, running, and crouch gait. We also illustrate that a point constraint and a weld constraint used to model foot-ground contact in previous studies produce inaccurate reaction moments and lead to contradictory interpretations of muscle function. To enable others to use and test these different constraint types (i.e., rolling, point, and weld constraints) we have included them as part of an induced acceleration analysis in OpenSim, a freely-available biomechanics simulation package. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Bite Forces and Their Measurement in Dogs and Cats

    Directory of Open Access Journals (Sweden)

    Se Eun Kim

    2018-04-01

    Full Text Available Bite force is generated by the interaction of the masticatory muscles, the mandibles and maxillae, the temporomandibular joints (TMJs, and the teeth. Several methods to measure bite forces in dogs and cats have been described. Direct in vivo measurement of a bite in dogs has been done; however, bite forces were highly variable due to animal volition, situation, or specific measurement technique. Bite force has been measured in vivo from anesthetized dogs by electrical stimulation of jaw adductor muscles, but this may not be reflective of volitional bite force during natural activity. In vitro bite forces have been estimated by calculation of the force produced using mechanical equations representing the jaw adductor muscles and of the mandible and skull structure Bite force can be estimated in silico using finite element analysis (FEA of the computed model of the anatomical structures. FEA can estimate bite force in extinct species; however, estimates may be lower than the measurements in live animals and would have to be validated specifically in domestic dogs and cats to be reliable. The main factors affecting the bite forces in dogs and cats are body weight and the skull’s morphology and size. Other factors such as oral pain, TMJ disorders, masticatory muscle atrophy, and malocclusion may also affect bite force. Knowledge of bite forces in dogs and cats is essential for various clinical and research fields such as the development of implants, materials, and surgical techniques as well as for forensic medicine. This paper is a summary of current knowledge of bite forces in dogs and cats, including the effect of measurement methods and of other factors.

  16. Bite Forces and Their Measurement in Dogs and Cats.

    Science.gov (United States)

    Kim, Se Eun; Arzi, Boaz; Garcia, Tanya C; Verstraete, Frank J M

    2018-01-01

    Bite force is generated by the interaction of the masticatory muscles, the mandibles and maxillae, the temporomandibular joints (TMJs), and the teeth. Several methods to measure bite forces in dogs and cats have been described. Direct in vivo measurement of a bite in dogs has been done; however, bite forces were highly variable due to animal volition, situation, or specific measurement technique. Bite force has been measured in vivo from anesthetized dogs by electrical stimulation of jaw adductor muscles, but this may not be reflective of volitional bite force during natural activity. In vitro bite forces have been estimated by calculation of the force produced using mechanical equations representing the jaw adductor muscles and of the mandible and skull structure Bite force can be estimated in silico using finite element analysis (FEA) of the computed model of the anatomical structures. FEA can estimate bite force in extinct species; however, estimates may be lower than the measurements in live animals and would have to be validated specifically in domestic dogs and cats to be reliable. The main factors affecting the bite forces in dogs and cats are body weight and the skull's morphology and size. Other factors such as oral pain, TMJ disorders, masticatory muscle atrophy, and malocclusion may also affect bite force. Knowledge of bite forces in dogs and cats is essential for various clinical and research fields such as the development of implants, materials, and surgical techniques as well as for forensic medicine. This paper is a summary of current knowledge of bite forces in dogs and cats, including the effect of measurement methods and of other factors.

  17. Bilateral ground reaction forces and joint moments for lateral sidestepping and crossover stepping tasks

    Science.gov (United States)

    Kuntze, Gregor; Sellers, William I.; Mansfield, Neil

    2009-01-01

    Racquet sports have high levels of joint injuries suggesting the joint loads during play may be excessive. Sports such as badminton employ lateral sidestepping (SS) and crossover stepping (XS) movements which so far have not been described in terms of biomechanics. This study examined bilateral ground reaction forces and three dimensional joint kinetics for both these gaits in order to determine the demands of the movements on the leading and trailing limb and predict the contribution of these movements to the occurrence of overuse injury of the lower limbs. A force platform and motion-analysis system were used to record ground reaction forces and track marker trajectories of 9 experienced male badminton players performing lateral SS, XS and forward running tasks at a controlled speed of 3 m·s-1 using their normal technique. Ground reaction force and kinetic data for the hip, knee and ankle were analyzed, averaged across the group and the biomechanical variables compared. In all cases the ground reaction forces and joint moments were less than those experienced during moderate running suggesting that in normal play SS and XS gaits do not lead to high forces that could contribute to increased injury risk. Ground reaction forces during SS and XS do not appear to contribute to the development of overuse injury. The distinct roles of the leading and trailing limb, acting as a generator of vertical force and shock absorber respectively, during the SS and XS may however contribute to the development of muscular imbalances which may ultimately contribute to the development of overuse injury. However it is still possible that faulty use of these gaits might lead to high loads and this should be the subject of future work. Key pointsGround reaction forces and joint moments during lateral stepping are smaller in magnitude than those experienced during moderate running.Force exposure in SS and XS gaits in normal play does not appear to contribute to the development of

  18. Analysis of the tractive force pattern on a knot by force measurement during laparoscopic knot tying.

    Science.gov (United States)

    Takayasu, Kenta; Yoshida, Kenji; Kinoshita, Hidefumi; Yoshimoto, Syunsuke; Oshiro, Osamu; Matsuda, Tadashi

    2017-07-19

    Quantifying surgical skills assists novice surgeons when learning operative techniques. We measured the interaction force at a ligation point and clarified the features of the force pattern among surgeons with different skill levels during laparoscopic knot tying. Forty-four surgeons were divided into three groups based on experience: 13 novice (0-5 years), 16 intermediate (6-15 years), and 15 expert (16-30 years). To assess the tractive force direction and volume during knot tying, we used a sensor that measures six force-torque values (x-axis: Fx, y-axis: Fy, z-axis: Fz, and xy-axis: Fxy) attached to a slit Penrose drain. All participants completed one double knot and five single knot sequences. We recorded completion time, force volume (FV), maximum force (MF), time over 1.5 N, duration of non-zero force, and percentage time when vertical force exceeded horizontal force (PTz). There was a significant difference between groups for completion time (p = 0.007); FV (total: p = 0.002; Fx: p = 0.004, Fy: p = 0.007, Fxy: p = 0.004, Fz: p force (p = 0.029); and PTz (p force pattern at the ligation point during suturing by surgeons with three levels of experience using a force measurement system. We revealed that both force volume and force direction differed depending on surgeons' skill level during knot tying. Copyright © 2017. Published by Elsevier Inc.

  19. Technology on precision measurement of torque and force

    International Nuclear Information System (INIS)

    2005-12-01

    This book gives a descriptions on force standards system about movement of object, direction and structure. Next, it deals with torque standards, torque measuring instrument and torque wrench with how to use, explanations, unit and test. This book written by Korea Association of standards and testing organizations is for exact measurement and test of force and torque.

  20. Dynamically adjustable foot-ground contact model to estimate ground reaction force during walking and running.

    Science.gov (United States)

    Jung, Yihwan; Jung, Moonki; Ryu, Jiseon; Yoon, Sukhoon; Park, Sang-Kyoon; Koo, Seungbum

    2016-03-01

    Human dynamic models have been used to estimate joint kinetics during various activities. Kinetics estimation is in demand in sports and clinical applications where data on external forces, such as the ground reaction force (GRF), are not available. The purpose of this study was to estimate the GRF during gait by utilizing distance- and velocity-dependent force models between the foot and ground in an inverse-dynamics-based optimization. Ten males were tested as they walked at four different speeds on a force plate-embedded treadmill system. The full-GRF model whose foot-ground reaction elements were dynamically adjusted according to vertical displacement and anterior-posterior speed between the foot and ground was implemented in a full-body skeletal model. The model estimated the vertical and shear forces of the GRF from body kinematics. The shear-GRF model with dynamically adjustable shear reaction elements according to the input vertical force was also implemented in the foot of a full-body skeletal model. Shear forces of the GRF were estimated from body kinematics, vertical GRF, and center of pressure. The estimated full GRF had the lowest root mean square (RMS) errors at the slow walking speed (1.0m/s) with 4.2, 1.3, and 5.7% BW for anterior-posterior, medial-lateral, and vertical forces, respectively. The estimated shear forces were not significantly different between the full-GRF and shear-GRF models, but the RMS errors of the estimated knee joint kinetics were significantly lower for the shear-GRF model. Providing COP and vertical GRF with sensors, such as an insole-type pressure mat, can help estimate shear forces of the GRF and increase accuracy for estimation of joint kinetics. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Effects of Sparring Load on Reaction Speed and Punch Force During the Precompetition and Competition Periods in Boxing.

    Science.gov (United States)

    Hukkanen, Esa; Häkkinen, Keijo

    2017-06-01

    Seven, male, national-level boxers (age, 20.3 ± 2.7 years; height, 1.80 ± 0.06 m; mass, 73.8 ± 11.1 kg) participated in this study to investigate the effects of sparring on reaction time and punch force of straight punches measured during the precompetition and competition periods. Heart rate and blood lactate concentrations were also monitored. Sparring load was chosen in accordance with the current rules: 3 × 3-minute bouts with 1-minute break in between. Reaction time of rear straight lengthened (p boxing-specific and explosive strength training.

  2. Effects of load on ground reaction force and lower limb kinematics during concentric squats.

    Science.gov (United States)

    Kellis, Eleftherios; Arambatzi, Fotini; Papadopoulos, Christos

    2005-10-01

    The purpose of this study was to examine the effects of external load on vertical ground reaction force, and linear and angular kinematics, during squats. Eight males aged 22.1 +/- 0.8 years performed maximal concentric squats using loads ranging from 7 to 70% of one-repetition maximum on a force plate while linear barbell velocity and the angular kinematics of the hip, knee and ankle were recorded. Maximum, average and angle-specific values were recorded. The ground reaction force ranged from 1.67 +/- 0.20 to 3.21 +/- 0.29 times body weight and increased significantly as external load increased (P squat exercises is not achieved at the same position of the lower body as external load is increased. In contrast, joint velocity coordination does not change as load is increased. The force-velocity relationship was linear and independent from the set of data used for its determination.

  3. Metabolic Rate and Ground Reaction Force During Motorized and Non-Motorized Treadmill Exercise

    Science.gov (United States)

    Everett, Meghan E.; Loehr, James A.; DeWitt, John K.; Laughlin, Mitzi; Lee, Stuart M. C.

    2010-01-01

    PURPOSE: To measure vertical ground reaction force (vGRF) and oxygen consumption (VO2) at several velocities during exercise using a ground-based version of the ISS treadmill in the M and NM modes. METHODS: Subjects (n = 20) walked or ran at 0.89, 1.34, 1.79, 2.24, 2.68, and 3.12 m/s while VO2 and vGRF data were collected. VO2 was measured using open-circuit spirometry (TrueOne 2400, Parvo-Medics). Data were averaged over the last 2 min of each 5-min stage. vGRF was measured in separate 15-s bouts at 125 Hz using custom-fitted pressure-sensing insoles (F-Scan Sport Sensors, Tekscan, Inc). A repeated-measures ANOVA was used to test for differences in VO2 and vGRF between M and NM and across speeds. Significance was set at P < 0.05. RESULTS: Most subjects were unable to exercise for 5 min at treadmill speeds above 1.79 m/s in the NM mode; however, vGRF data were obtained for all subjects at each speed in both modes. VO2 was approx.40% higher during NM than M exercise across treadmill speeds. vGRF increased with treadmill speed but was not different between modes. CONCLUSION: Higher VO2 with no change in vGRF suggests that the additional metabolic cost associated with NM treadmill exercise is accounted for in the horizontal forces required to move the treadmill belt. Although this may limit the exercise duration at faster speeds, high-intensity NM exercise activates the hamstrings and plantarflexors, which are not specifically targeted or well protected by other in-flight countermeasures.

  4. Recent Investments by NASA's National Force Measurement Technology Capability

    Science.gov (United States)

    Commo, Sean A.; Ponder, Jonathan D.

    2016-01-01

    The National Force Measurement Technology Capability (NFMTC) is a nationwide partnership established in 2008 and sponsored by NASA's Aeronautics Evaluation and Test Capabilities (AETC) project to maintain and further develop force measurement capabilities. The NFMTC focuses on force measurement in wind tunnels and provides operational support in addition to conducting balance research. Based on force measurement capability challenges, strategic investments into research tasks are designed to meet the experimental requirements of current and future aerospace research programs and projects. This paper highlights recent and force measurement investments into several areas including recapitalizing the strain-gage balance inventory, developing balance best practices, improving calibration and facility capabilities, and researching potential technologies to advance balance capabilities.

  5. Ground reaction force comparison of controlled resistance methods to isoinertial loading of the squat exercise - biomed 2010.

    Science.gov (United States)

    Paulus, David C; Reynolds, Michael C; Schilling, Brian K

    2010-01-01

    The ground reaction force during the concentric (raising) portion of the squat exercise was compared to that of isoinertial loading (free weights) for three pneumatically controlled resistance methods: constant resistance, cam force profile, and proportional force control based on velocity. Constant force control showed lower ground reaction forces than isoinertial loading throughout the range of motion (ROM). The cam force profile exhibited slightly greater ground reaction forces than isoinertial loading at 10 and 40% ROM with fifty-percent greater loading at 70% ROM. The proportional force control consistently elicited greater ground reaction force than isoinertial loading, which progressively ranged from twenty to forty percent increase over isoinertial loading except for being approximately equal at 85% ROM. Based on these preliminary results, the proportional control shows the most promise for providing loading that is comparable in magnitude to isoinertial loading. This technology could optimize resistance exercise for sport-specific training or as a countermeasure to atrophy during spaceflight.

  6. Sit-to-stand ground reaction force characteristics in blind and sighted female children.

    Science.gov (United States)

    Faraji Aylar, Mozhgan; Jafarnezhadgero, Amir Ali; Salari Esker, Fatemeh

    2018-03-05

    The association between visual sensory and sit-to-stand ground reaction force characteristics is not clear. Impulse is the amount of force applied over a period of time. Also, free moment represents the vertical moment applied in the center of pressure (COP). How the ground reaction force components, vertical loading rate, impulses and free moment respond to long and short term restricted visual information? Fifteen female children with congenital blindness and 45 healthy girls with no visual impairments participated in this study. The girls with congenital blindness were placed in one group and the 45 girls with no visual impairments were randomly divided into three groups of 15; eyes open, permanently eyes closed, and temporary eyes closed. The participants in the permanently eyes closed group closed their eyes for 20 min before the test, whereas temporary eyes closed group did tests with their eyes closed throughout, and those in the eyes open group kept their eyes open. Congenital blindness was associated with increased vertical loading rate, range of motion of knee and hip in the medio-lateral plane. Also, medio-lateral and vertical ground reaction force impulses. Similar peak negative and positive free moments were observed in three groups. In conclusion, the results reveal that sit-to-stand ground reaction force components in blind children may have clinical importance for improvement of balance control of these individuals. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. Air Force Maintenance Technician Performance Measurement.

    Science.gov (United States)

    1979-12-28

    aMbr) ATTACHED DD , . - , .147-3 ",, EDITIoN o Fo NOV 66 IS O SOLETE 8,C) 9iCLAS S I r! ABSTRA CT Title: AIR FORCE MAINTENANCE T-,-NIIAN PERFCRMANCZ M...directions have 43 been edited to c’-nf:rm to Uhrbrock’s (1961) rules for a-zraisai forms, i.e., thoup-hts are expressed clearly and si-z!y, staze- ments...Yillarl, -Iheed 19 ,4., F. 1-ut .h ..s, ar .L . ’I’t-.man- -...." , e 3reakthrough for ?erfcrmance .- aisa !." 3usiness Horizons, 1076, 1, 66-73. Yiner, J

  8. Effects of knee extension constraint training on knee flexion angle and peak impact ground-reaction force.

    Science.gov (United States)

    Liu, Hui; Wu, Will; Yao, Wanxiang; Spang, Jeffrey T; Creighton, R Alexander; Garrett, William E; Yu, Bing

    2014-04-01

    Low compliance with training programs is likely to be one of the major reasons for inconsistency of the data regarding the effectiveness of current anterior cruciate ligament (ACL) injury prevention programs. Training methods that reduce training time and cost could favorably influence the effectiveness of ACL injury prevention programs. A newly designed knee extension constraint training device may serve this purpose. (1) Knee extension constraint training for 4 weeks would significantly increase the knee flexion angle at the time of peak impact posterior ground-reaction force and decrease peak impact ground-reaction forces during landing of a stop-jump task and a side-cutting task, and (2) the training effects would be retained 4 weeks after completion of the training program. Controlled laboratory study. Twenty-four recreational athletes were randomly assigned to group A or B. Participants in group A played sports without wearing a knee extension constraint device for 4 weeks and then played sports while wearing the device for 4 weeks, while participants in group B underwent a reversed protocol. Both groups were tested at the beginning of week 1 and at the ends of weeks 4 and 8 without wearing the device. Knee joint angles were obtained from 3-dimensional videographic data, while ground-reaction forces were measured simultaneously using force plates. Analyses of variance were performed to determine the training effects and the retention of training effects. Participants in group A significantly increased knee flexion angles and decreased ground-reaction forces at the end of week 8 (P ≤ .012). Participants in group B significantly increased knee flexion angles and decreased ground-reaction forces at the ends of weeks 4 and 8 (P ≤ .007). However, participants in group B decreased knee flexion angles and increased ground-reaction forces at the end of week 8 in comparison with the end of week 4 (P ≤ .009). Knee extension constraint training for 4 weeks

  9. Classical Wigner method with an effective quantum force: application to reaction rates.

    Science.gov (United States)

    Poulsen, Jens Aage; Li, Huaqing; Nyman, Gunnar

    2009-07-14

    We construct an effective "quantum force" to be used in the classical molecular dynamics part of the classical Wigner method when determining correlation functions. The quantum force is obtained by estimating the most important short time separation of the Feynman paths that enter into the expression for the correlation function. The evaluation of the force is then as easy as classical potential energy evaluations. The ideas are tested on three reaction rate problems. The resulting transmission coefficients are in much better agreement with accurate results than transmission coefficients from the ordinary classical Wigner method.

  10. Ground reaction forces, kinematics, and muscle activations during the windmill softball pitch.

    Science.gov (United States)

    Oliver, Gretchen D; Plummer, Hillary

    2011-07-01

    The aims of the present study were to examine quantitatively ground reaction forces, kinematics, and muscle activations during the windmill softball pitch, and to determine relationships between knee valgus and muscle activations, ball velocity and muscle activation as well as ball velocity and ground reaction forces. It was hypothesized that there would be an inverse relationship between degree of knee valgus and muscle activation, a direct relationship between ground reaction forces and ball velocity, and non-stride leg muscle activations and ball velocity. Ten female windmill softball pitchers (age 17.6 ± 3.47 years, stature 1.67 ± 0.07 m, weight 67.4 ± 12.2 kg) participated. Dependent variables were ball velocity, surface electromyographic (sEMG), kinematic, and kinetic data while the participant was the independent variable. Stride foot contact reported peak vertical forces of 179% body weight. There were positive relationships between ball velocity and ground reaction force (r = 0.758, n = 10, P = 0.029) as well as ball velocity and non-stride leg gluteus maximus (r = 0.851, n = 10, P = 0.007) and medius (r = 0.760, n = 10, P = 0.029) muscle activity, while there was no notable relationship between knee valgus and muscle activation. As the windmill softball pitcher increased ball velocity, her vertical ground reaction forces also increased. Proper conditioning of the lumbopelvic-hip complex, including the gluteals, is essential for injury prevention. From the data presented, it is evident that bilateral strength and conditioning of the gluteal muscle group is salient in the windmill softball pitch as an attempt to decrease incidence of injury.

  11. Adaptive locomotor training on an end-effector gait robot: evaluation of the ground reaction forces in different training conditions.

    Science.gov (United States)

    Tomelleri, Christopher; Waldner, Andreas; Werner, Cordula; Hesse, Stefan

    2011-01-01

    The main goal of robotic gait rehabilitation is the restoration of independent gait. To achieve this goal different and specific patterns have to be practiced intensively in order to stimulate the learning process of the central nervous system. The gait robot G-EO Systems was designed to allow the repetitive practice of floor walking, stair climbing and stair descending. A novel control strategy allows training in adaptive mode. The force interactions between the foot and the ground were analyzed on 8 healthy volunteers in three different conditions: real floor walking on a treadmill, floor walking on the gait robot in passive mode, floor walking on the gait robot in adaptive mode. The ground reaction forces were measured by a Computer Dyno Graphy (CDG) analysis system. The results show different intensities of the ground reaction force across all of the three conditions. The intensities of force interactions during the adaptive training mode are comparable to the real walking on the treadmill. Slight deviations still occur in regard to the timing pattern of the forces. The adaptive control strategy comes closer to the physiological swing phase than the passive mode and seems to be a promising option for the treatment of gait disorders. Clinical trials will validate the efficacy of this new option in locomotor therapy on the patients. © 2011 IEEE

  12. A test on reactive force fields for the study of silica dimerization reactions

    Energy Technology Data Exchange (ETDEWEB)

    Moqadam, Mahmoud; Riccardi, Enrico; Trinh, Thuat T.; Åstrand, Per-Olof; Erp, Titus S. van, E-mail: titus.van.erp@ntnu.no [Department of Chemistry, Norwegian University of Science and Technology (NTNU), Høgskoleringen 5, Realfagbygget D3-117, 7491 Trondheim (Norway)

    2015-11-14

    We studied silica dimerization reactions in the gas and aqueous phase by density functional theory (DFT) and reactive force fields based on two parameterizations of ReaxFF. For each method (both ReaxFF force fields and DFT), we performed constrained geometry optimizations, which were subsequently evaluated in single point energy calculations using the other two methods. Standard fitting procedures typically compare the force field energies and geometries with those from quantum mechanical data after a geometry optimization. The initial configurations for the force field optimization are usually the minimum energy structures of the ab initio database. Hence, the ab initio method dictates which structures are being examined and force field parameters are being adjusted in order to minimize the differences with the ab initio data. As a result, this approach will not exclude the possibility that the force field predicts stable geometries or low transition states which are realistically very high in energy and, therefore, never considered by the ab initio method. Our analysis reveals the existence of such unphysical geometries even at unreactive conditions where the distance between the reactants is large. To test the effect of these discrepancies, we launched molecular dynamics simulations using DFT and ReaxFF and observed spurious reactions for both ReaxFF force fields. Our results suggest that the standard procedures for parameter fitting need to be improved by a mutual comparative method.

  13. Bite force measurement based on fiber Bragg grating sensor

    Science.gov (United States)

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

    2017-10-01

    The maximum level of voluntary bite force, which results from the combined action of muscle of mastication, joints, and teeth, i.e., craniomandibular structure, is considered as one of the major indicators for the functional state of the masticatory system. Measurement of voluntary bite force provides useful data for the jaw muscle function and activity along with assessment of prosthetics. This study proposes an in vivo methodology for the dynamic measurement of bite force employing a fiber Bragg grating (FBG) sensor known as bite force measurement device (BFMD). The BFMD developed is a noninvasive intraoral device, which transduces the bite force exerted at the occlusal surface into strain variations on a metal plate. These strain variations are acquired by the FBG sensor bonded over it. The BFMD developed facilitates adjustment of the distance between the biting platform, which is essential to capture the maximum voluntary bite force at three different positions of teeth, namely incisor, premolar, and molar sites. The clinically relevant bite forces are measured at incisor, molar, and premolar position and have been compared against each other. Furthermore, the bite forces measured with all subjects are segregated according to gender and also compared against each other.

  14. A method for measuring light ion reaction cross sections

    International Nuclear Information System (INIS)

    Carlson, R.F.; Ingemarsson, A.; Lantz, M.

    2005-03-01

    An experimental procedure for measuring reaction cross sections of light ions in the energy range 20-50 MeV/nucleon, using a modified attenuation technique, is described. The detection method incorporates a forward detector that simultaneously measures the reaction cross sections for five different sizes of the solid angles in steps from 99.1 to 99.8% of the total solid angle. The final reaction cross section values are obtained by extrapolation to the full solid angle

  15. Toward Direct Reaction-in-Flight Measurements

    Science.gov (United States)

    Wilhelmy, Jerry; Bredeweg, Todd; Fowler, Malcolm; Gooden, Matthew; Hayes, Anna; Rusev, Gencho; Caggiano, Joseph; Hatarik, Robert; Henry, Eugene; Tonchev, Anton; Yeaman, Charles; Bhike, Megha; Krishichayan, Krishi; Tornow, Werner

    2016-03-01

    At the National Ignition Facility (NIF) neutrons having energies greater than the equilibrium 14.1 MeV value can be produced via Reaction-in-Flight (RIF) interactions between plasma atoms and upscattered D or T ions. The yield and spectrum of these RIF produced neutrons carry information on the plasma properties as well as information on the stopping power of ions under plasma conditions. At NIF the yield of these RIF neutrons is predicted to be 4-7 orders of magnitude below the peak 14 MeV neutron yield. The current generation of neutron time of flight (nTOF) instrumentation has so far been incapable of detecting these low-yield neutrons primarily due to high photon backgrounds. To date, information on RIF neutrons has been obtained in integral activation experiments using reactions with high energy thresholds such as 169Tm(n,3n)167Tm and 209Bi(n,4n) 206Bi. Initial experiments to selectively suppress photon backgrounds have been performed at TUNL using pulsed monoenergetic neutron beams of 14.9, 18.5, 24.2, and 28.5 MeV impinging on a Bibenzyl scintillator. By placing 5 cm of Pb before the scintillator we were able to selectively suppress the photons from the flash occurring at the production target and enhance the n/_signal by ~6 times.

  16. Uncertainties in forces extracted from non-contact atomic force microscopy measurements by fitting of long-range background forces

    Directory of Open Access Journals (Sweden)

    Adam Sweetman

    2014-04-01

    Full Text Available In principle, non-contact atomic force microscopy (NC-AFM now readily allows for the measurement of forces with sub-nanonewton precision on the atomic scale. In practice, however, the extraction of the often desired ‘short-range’ force from the experimental observable (frequency shift is often far from trivial. In most cases there is a significant contribution to the total tip–sample force due to non-site-specific van der Waals and electrostatic forces. Typically, the contribution from these forces must be removed before the results of the experiment can be successfully interpreted, often by comparison to density functional theory calculations. In this paper we compare the ‘on-minus-off’ method for extracting site-specific forces to a commonly used extrapolation method modelling the long-range forces using a simple power law. By examining the behaviour of the fitting method in the case of two radically different interaction potentials we show that significant uncertainties in the final extracted forces may result from use of the extrapolation method.

  17. Probing Anisotropic Surface Properties of Molybdenite by Direct Force Measurements.

    Science.gov (United States)

    Lu, Zhenzhen; Liu, Qingxia; Xu, Zhenghe; Zeng, Hongbo

    2015-10-27

    Probing anisotropic surface properties of layer-type mineral is fundamentally important in understanding its surface charge and wettability for a variety of applications. In this study, the surface properties of the face and the edge surfaces of natural molybdenite (MoS2) were investigated by direct surface force measurements using atomic force microscope (AFM). The interaction forces between the AFM tip (Si3N4) and face or edge surface of molybdenite were measured in 10 mM NaCl solutions at various pHs. The force profiles were well-fitted with classical DLVO (Derjaguin-Landau-Verwey-Overbeek) theory to determine the surface potentials of the face and the edge surfaces of molybdenite. The surface potentials of both the face and edge surfaces become more negative with increasing pH. At neutral and alkaline conditions, the edge surface exhibits more negative surface potential than the face surface, which is possibly due to molybdate and hydromolybdate ions on the edge surface. The point of zero charge (PZC) of the edge surface was determined around pH 3 while PZC of the face surface was not observed in the range of pH 3-11. The interaction forces between octadecyltrichlorosilane-treated AFM tip (OTS-tip) and face or edge surface of molybdenite were also measured at various pHs to study the wettability of molybdenite surfaces. An attractive force between the OTS-tip and the face surface was detected. The force profiles were well-fitted by considering DLVO forces and additional hydrophobic force. Our results suggest the hydrophobic feature of the face surface of molybdenite. In contrast, no attractive force between the OTS-tip and the edge surface was detected. This is the first study in directly measuring surface charge and wettability of the pristine face and edge surfaces of molybdenite through surface force measurements.

  18. Nanonewton force measurement using a modified Michelson interferometer

    International Nuclear Information System (INIS)

    Tahviliyan, Masoud; Charsooghi, Mohammad A; Akhlaghi, Ehsan A; Taghi Tavassoly, Mohammad

    2017-01-01

    In this paper, we introduce a new method to measure forces in the nanonewton range. The method is based on modification of a Michelson interferometer in which the rigid mirrors are replaced with two thin rod-like mirrors. One of the rod-like mirrors is fixed at both ends and the other has one free end. As the mirror with free end deflects in response to an applied force the spatial interference pattern is changed. Analysis of the interference fringes provides a readout of the rod deflection and thereby the applied force. The device is calibrated by applying known forces to the mirror with a free end and measuring the resulting displacement. Two different methods, mechanical and electrostatic, are used for calibration. The precision of the measurements and the propagation of the calibration uncertainty are investigated. The results show that this optical method is a good candidate for detecting small forces in the nanonewton range. (paper)

  19. Molecular force sensors to measure stress in cells

    International Nuclear Information System (INIS)

    Prabhune, Meenakshi; Rehfeldt, Florian; Schmidt, Christoph F

    2017-01-01

    Molecularly generated forces are essential for most activities of biological cells, but also for the maintenance of steady state or homeostasis. To quantitatively understand cellular dynamics in migration, division, or mechanically guided differentiation, it will be important to exactly measure stress fields within the cell and the extracellular matrix. Traction force microscopy and related techniques have been established to determine the stress transmitted from adherent cells to their substrates. However, different approaches are needed to directly assess the stress generated inside the cell. This has recently led to the development of novel molecular force sensors. In this topical review, we briefly mention methods used to measure cell-external forces, and then summarize and explain different designs for the measurement of cell-internal forces with their respective advantages and disadvantages. (topical review)

  20. In-Shoe Plantar Pressures and Ground Reaction Forces during Overweight Adults' Overground Walking

    Science.gov (United States)

    de Castro, Marcelo P.; Abreu, Sofia C.; Sousa, Helena; Machado, Leandro; Santos, Rubim; Vilas-Boas, João Paulo

    2014-01-01

    Purpose: Because walking is highly recommended for prevention and treatment of obesity and some of its biomechanical aspects are not clearly understood for overweight people, we compared the absolute and normalized ground reaction forces (GRF), plantar pressures, and temporal parameters of normal-weight and overweight participants during…

  1. Do ground reaction forces during unilateral and bilateral movements exhibit compensation strategies following ACL reconstruction?

    NARCIS (Netherlands)

    Baumgart, Christian; Schubert, Markus; Hoppe, Matthias W.; Gokeler, Alli; Freiwald, Juergen

    The aims of the study were (1) to evaluate the leg asymmetry assessed with ground reaction forces (GRFs) during unilateral and bilateral movements of different knee loads in anterior cruciate ligament (ACL) reconstructed patients and (2) to investigate differences in leg asymmetry depending on the

  2. Ground reaction forces and kinematics in distance running in older-aged men

    NARCIS (Netherlands)

    Bus, Sicco A.

    2003-01-01

    Purpose: The biomechanics of distance running has not been studied before in older-aged runners but may be different than in younger-aged runners because of musculoskeletal degeneration at older age. This study aimed at determining whether the stance phase kinematics and ground reaction forces in

  3. Brownian motion in a field of force and the diffusion theory of chemical reactions. II

    NARCIS (Netherlands)

    Brinkman, H.C.

    1956-01-01

    H. A. Kramers has studied the rate of chemical reactions in view of the Brownian forces caused by a surrounding medium in temperature equilibrium. In a previous paper 3) the author gave a solution of Kramers' diffusion equation in phase space by systematic development. In this paper the general

  4. Techniques of Force and Pressure Measurement in the Small Joints of the Wrist.

    Science.gov (United States)

    Schreck, Michael J; Kelly, Meghan; Canham, Colin D; Elfar, John C

    2018-01-01

    The alteration of forces across joints can result in instability and subsequent disability. Previous methods of force measurements such as pressure-sensitive films, load cells, and pressure-sensing transducers have been utilized to estimate biomechanical forces across joints and more recent studies have utilized a nondestructive method that allows for assessment of joint forces under ligamentous restraints. A comprehensive review of the literature was performed to explore the numerous biomechanical methods utilized to estimate intra-articular forces. Methods of biomechanical force measurements in joints are reviewed. Methods such as pressure-sensitive films, load cells, and pressure-sensing transducers require significant intra-articular disruption and thus may result in inaccurate measurements, especially in small joints such as those within the wrist and hand. Non-destructive methods of joint force measurements either utilizing distraction-based joint reaction force methods or finite element analysis may offer a more accurate assessment; however, given their recent inception, further studies are needed to improve and validate their use.

  5. Force measurements on a shielded coreless linear permanent magnet motor

    NARCIS (Netherlands)

    Pluk, K.J.W.; Jansen, J.W.; Lomonova, E.A.

    2014-01-01

    This paper compares force measurements on a shielded coreless linear permanent magnet motor with 2-D models. A 2-D semianalytical modeling method is applied, which is based on Fourier modeling and includes force calculations. The semianalytical modeling correctly predicts the behavior found in the

  6. Reduction of Liquid Bridge Force for 3D Microstructure Measurements

    Directory of Open Access Journals (Sweden)

    Hiroshi Murakami

    2016-05-01

    Full Text Available Recent years have witnessed an increased demand for a method for precise measurement of the microstructures of mechanical microparts, microelectromechanical systems, micromolds, optical devices, microholes, etc. This paper presents a measurement system for three-dimensional (3D microstructures that use an optical fiber probe. This probe consists of a stylus shaft with a diameter of 2.5 µm and a glass ball with a diameter of 5 µm attached to the stylus tip. In this study, the measurement system, placed in a vacuum vessel, is constructed suitably to prevent adhesion of the stylus tip to the measured surface caused by the surface force resulting from the van der Waals force, electrostatic force, and liquid bridge force. First, these surface forces are analyzed with the aim of investigating the causes of adhesion. Subsequently, the effects of pressure inside the vacuum vessel on surface forces are evaluated. As a result, it is found that the surface force is 0.13 µN when the pressure inside the vacuum vessel is 350 Pa. This effect is equivalent to a 60% reduction in the surface force in the atmosphere.

  7. Does shoe heel design influence ground reaction forces and knee moments during maximum lunges in elite and intermediate badminton players?

    Directory of Open Access Journals (Sweden)

    Wing-Kai Lam

    Full Text Available Lunge is one frequently executed movement in badminton and involves a unique sagittal footstrike angle of more than 40 degrees at initial ground contact compared with other manoeuvres. This study examined if the shoe heel curvature design of a badminton shoe would influence shoe-ground kinematics, ground reaction forces, and knee moments during lunge.Eleven elite and fifteen intermediate players performed five left-forward maximum lunge trials with Rounded Heel Shoe (RHS, Flattened Heel Shoe (FHS, and Standard Heel Shoes (SHS. Shoe-ground kinematics, ground reaction forces, and knee moments were measured by using synchronized force platform and motion analysis system. A 2 (Group x 3 (Shoe ANOVA with repeated measures was performed to determine the effects of different shoes and different playing levels, as well as the interaction of two factors on all variables.Shoe effect indicated that players demonstrated lower maximum vertical loading rate in RHS than the other two shoes (P < 0.05. Group effect revealed that elite players exhibited larger footstrike angle, faster approaching speed, lower peak horizontal force and horizontal loading rates but higher vertical loading rates and larger peak knee flexion and extension moments (P < 0.05. Analysis of Interactions of Group x Shoe for maximum and mean vertical loading rates (P < 0.05 indicated that elite players exhibited lower left maximum and mean vertical loading rates in RHS compared to FHS (P < 0.01, while the intermediate group did not show any Shoe effect on vertical loading rates.These findings indicate that shoe heel curvature would play some role in altering ground reaction force impact during badminton lunge. The differences in impact loads and knee moments between elite and intermediate players may be useful in optimizing footwear design and training strategy to minimize the potential risks for impact related injuries in badminton.

  8. Lower limb ice application alters ground reaction force during gait initiation

    Directory of Open Access Journals (Sweden)

    Thiago B. Muniz

    2015-04-01

    Full Text Available BACKGROUND: Cryotherapy is a widely used technique in physical therapy clinics and sports. However, the effects of cryotherapy on dynamic neuromuscular control are incompletely explained. OBJECTIVES: To evaluate the effects of cryotherapy applied to the calf, ankle and sole of the foot in healthy young adults on ground reaction forces during gait initiation. METHOD: This study evaluated the gait initiation forces, maximum propulsion, braking forces and impulses of 21 women volunteers through a force platform, which provided maximum and minimum ground reaction force values. To assess the effects of cooling, the task - gait initiation - was performed before ice application, immediately after and 30 minutes after removal of the ice pack. Ice was randomly applied on separate days to the calf, ankle and sole of the foot of the participants. RESULTS: It was demonstrated that ice application for 30 minutes to the sole of the foot and calf resulted in significant changes in the vertical force variables, which returned to their pre-application values 30 minutes after the removal of the ice pack. Ice application to the ankle only reduced propulsion impulse. CONCLUSIONS: These results suggest that although caution is necessary when performing activities that require good gait control, the application of ice to the ankle, sole of the foot or calf in 30-minute intervals may be safe even preceding such activities.

  9. Force Measurements on a VAWT Blade in Parked Conditions

    Directory of Open Access Journals (Sweden)

    Anders Goude

    2017-11-01

    Full Text Available The forces on a turbine at extreme wind conditions when the turbine is parked is one of the most important design cases for the survivability of a turbine. In this work, the forces on a blade and its support arms have been measured on a 12 kW straight-bladed vertical axis wind turbine at an open site. Two cases are tested: one during electrical braking of the turbine, which allows it to rotate slowly, and one with the turbine mechanically fixed with the leading edge of the blade facing the main wind direction. The force variations with respect to wind direction are investigated, and it is seen that significant variations in forces depend on the wind direction. The measurements show that for the fixed case, when subjected to the same wind speed, the forces are lower when the blade faces the wind direction. The results also show that due to the lower forces at this particular wind direction, the average forces for the fixed blade are notably lower. Hence, it is possible to reduce the forces on a turbine blade, simply by taking the dominating wind direction into account when the turbine is parked. The measurements also show that a positive torque is generated from the blade for most wind directions, which causes the turbine to rotate in the electrically-braked case. These rotations will cause increased fatigue loads on the turbine blade.

  10. Cutting force measurement of electrical jigsaw by strain gauges

    International Nuclear Information System (INIS)

    Kazup, L; Varadine Szarka, A

    2016-01-01

    This paper describes a measuring method based on strain gauges for accurate specification of electric jigsaw's cutting force. The goal of the measurement is to provide an overall perspective about generated forces in a jigsaw's gearbox during a cutting period. The lifetime of the tool is affected by these forces primarily. This analysis is part of the research and development project aiming to develop a special linear magnetic brake for realizing automatic lifetime tests of electric jigsaws or similar handheld tools. The accurate specification of cutting force facilitates to define realistic test cycles during the automatic lifetime test. The accuracy and precision resulted by the well described cutting force characteristic and the possibility of automation provide new dimension for lifetime testing of the handheld tools with alternating movement. (paper)

  11. Enzyme reactions and their time resolved measurements

    International Nuclear Information System (INIS)

    Hajdu, Janos

    1990-01-01

    This paper discusses experimental strategies in data collection with the Laue method and summarises recent results using synchrotron radiation. Then, an assessment is made of the progress towards time resolved studies with protein crystals and the problems that remain. The paper consists of three parts which respectively describe some aspects of Laue diffraction, recent examples of structural results from Laue diffraction, and kinetic Laue crystallography. In the first part, characteristics of Laue diffraction is discussed first, focusing on the harmonics problems, spatials problem, wavelength normalization, low resolution hole, data completeness, and uneven coverage of reciprocal space. Then, capture of the symmetry unique reflection set is discussed focusing on the effect of wavelength range on the number of reciprocal lattice points occupying diffracting positions, effect of crystal to film distance and the film area and shape on the number of reflections captured, and effect of crystal symmetry on the number of unique reflections within the number of reflections captured. The second part addresses the determination of the structure of turkey egg white lysozyme, and calcium binding in tomato bushy stunt virus. The third part describes the initiation of reactions in enzyme crystals, picosecond Laue diffraction at high energy storage rings, and detectors. (N.K.)

  12. Sub-Angstrom oscillation amplitude non-contact atomic force microscopy for lateral force gradient measurement

    International Nuclear Information System (INIS)

    Atabak, Mehrdad; Unverdi, Ozhan; Ozer, H. Ozguer; Oral, Ahmet

    2009-01-01

    We report the first results from novel sub-Angstrom oscillation amplitude non-contact atomic force microscopy developed for lateral force gradient measurements. Quantitative lateral force gradients between a tungsten tip and Si(1 1 1)-(7 x 7) surface can be measured using this microscope. Simultaneous lateral force gradient and scanning tunnelling microscope images of single and multi atomic steps are obtained. In our measurement, tunnel current is used as feedback. The lateral stiffness contrast has been observed to be 2.5 N/m at single atomic step, in contrast to 13 N/m at multi atomic step on Si(1 1 1) surface. We also carried out a series of lateral stiffness-distance spectroscopy. We observed lateral stiffness-distance curves exhibit sharp increase in the stiffness as the sample is approached towards the surface. We usually observed positive stiffness and sometimes going into slightly negative region.

  13. Quantitative measurements of shear displacement using atomic force microscopy

    International Nuclear Information System (INIS)

    Wang, Wenbo; Wu, Weida; Sun, Ying; Zhao, Yonggang

    2016-01-01

    We report a method to quantitatively measure local shear deformation with high sensitivity using atomic force microscopy. The key point is to simultaneously detect both torsional and buckling motions of atomic force microscopy (AFM) cantilevers induced by the lateral piezoelectric response of the sample. This requires the quantitative calibration of torsional and buckling response of AFM. This method is validated by measuring the angular dependence of the in-plane piezoelectric response of a piece of piezoelectric α-quartz. The accurate determination of the amplitude and orientation of the in-plane piezoelectric response, without rotation, would greatly enhance the efficiency of lateral piezoelectric force microscopy.

  14. Loading Configurations and Ground Reaction Forces During Treadmill Running in Weightlessness

    Science.gov (United States)

    DeWitt, John; Schaffner, Grant; Blazine, Kristi; Bentley, Jason; Laughlin, Mitzi; Loehr, James; Hagan, Donald

    2003-01-01

    Studies have shown losses in bone mineral density of 1-2% per month in critical weight bearing areas such as the proximal femur during long-term space flight (Grigoriev, 1998). The astronauts currently onboard the International Space Station (ISS) use a treadmill as an exercise countermeasure to bone loss that occurs as a result of prolonged exposure to weightlessness. A crewmember exercising on the treadmill is attached by a harness and loading device. Ground reaction forces are obtained through the loading device that pulls the crewn1ember towards the treadmill surface during locomotion. McCrory et al. (2002) found that the magnitude of the peak ground reaction force (pGRF) during horizontal suspension running, or simulated weightlessness, was directly related to the load applied to the subject. It is thought that strain magnitude and strain rate affects osteogenesis, and is a function of the magnitude and rate of change of the ground reaction force. While it is not known if a minimum stimulus exists for osteogenesis, it has been hypothesized that in order to replicate the bone formation occurring in normal gravity (1 G), the exercise in weightlessness should mimic the forces that occur on earth. Specifically, the pGRF obtained in weightlessness should be comparable to that achieved in 1 G.

  15. Electromagnetic radiation reaction force and radiation potential in general five-dimensional relativity

    International Nuclear Information System (INIS)

    Lo, C.Y.; Goldstein, G.R.; Napier, A.

    1989-01-01

    A unified theory of electromagnetic and gravitational fields should modify classical electrodynamics to account for the radiation reaction force. A conjecture that the radiation reaction force and the Lorentz force should be distinct, but in unified forms, results in a five-dimensional unified theory of five variables. It is found that a semicylindrical condition can reconcile the apparent differences between a five-dimensional physical space and our four-dimensional perceptions. Analysis of the geodesic equations results in the notion of gauge dynamics which manifests the influence of the unrestricted fifth variable. The element g 55 of the five-dimensional metric is identified as the radiation potential, which can directly determine the radiation reaction force. This gives a distinct physical origin for the radiation process in classical theory. The potential suggests that the electron can have excited states in quantum electrodynamics. This theory is supported with calculations which demonstrate that the motion of the fifth variable directly causes physical changes in the four-dimensional subspace

  16. Uncertainty quantification in nanomechanical measurements using the atomic force microscope

    Science.gov (United States)

    Ryan Wagner; Robert Moon; Jon Pratt; Gordon Shaw; Arvind Raman

    2011-01-01

    Quantifying uncertainty in measured properties of nanomaterials is a prerequisite for the manufacture of reliable nanoengineered materials and products. Yet, rigorous uncertainty quantification (UQ) is rarely applied for material property measurements with the atomic force microscope (AFM), a widely used instrument that can measure properties at nanometer scale...

  17. Ground reaction force estimates from ActiGraph GT3X+ hip accelerations.

    Directory of Open Access Journals (Sweden)

    Jennifer M Neugebauer

    Full Text Available Simple methods to quantify ground reaction forces (GRFs outside a laboratory setting are needed to understand daily loading sustained by the body. Here, we present methods to estimate peak vertical GRF (pGRFvert and peak braking GRF (pGRFbrake in adults using raw hip activity monitor (AM acceleration data. The purpose of this study was to develop a statistically based model to estimate pGRFvert and pGRFbrake during walking and running from ActiGraph GT3X+ AM acceleration data. 19 males and 20 females (age 21.2 ± 1.3 years, height 1.73 ± 0.12 m, mass 67.6 ± 11.5 kg wore an ActiGraph GT3X+ AM over their right hip. Six walking and six running trials (0.95-2.19 and 2.20-4.10 m/s, respectively were completed. Average of the peak vertical and anterior/posterior AM acceleration (ACCvert and ACCbrake, respectively and pGRFvert and pGRFbrake during the stance phase of gait were determined. Thirty randomly selected subjects served as the training dataset to develop generalized equations to predict pGRFvert and pGRFbrake. Using a holdout approach, the remaining 9 subjects were used to test the accuracy of the models. Generalized equations to predict pGRFvert and pGRFbrake included ACCvert and ACCbrake, respectively, mass, type of locomotion (walk or run, and type of locomotion acceleration interaction. The average absolute percent differences between actual and predicted pGRFvert and pGRFbrake were 8.3% and 17.8%, respectively, when the models were applied to the test dataset. Repeated measures generalized regression equations were developed to predict pGRFvert and pGRFbrake from ActiGraph GT3X+ AM acceleration for young adults walking and running. These equations provide a means to estimate GRFs without a force plate.

  18. Estimation of Ground Reaction Forces and Moments During Gait Using Only Inertial Motion Capture

    Directory of Open Access Journals (Sweden)

    Angelos Karatsidis

    2016-12-01

    Full Text Available Ground reaction forces and moments (GRF&M are important measures used as input in biomechanical analysis to estimate joint kinetics, which often are used to infer information for many musculoskeletal diseases. Their assessment is conventionally achieved using laboratory-based equipment that cannot be applied in daily life monitoring. In this study, we propose a method to predict GRF&M during walking, using exclusively kinematic information from fully-ambulatory inertial motion capture (IMC. From the equations of motion, we derive the total external forces and moments. Then, we solve the indeterminacy problem during double stance using a distribution algorithm based on a smooth transition assumption. The agreement between the IMC-predicted and reference GRF&M was categorized over normal walking speed as excellent for the vertical (ρ = 0.992, rRMSE = 5.3%, anterior (ρ = 0.965, rRMSE = 9.4% and sagittal (ρ = 0.933, rRMSE = 12.4% GRF&M components and as strong for the lateral (ρ = 0.862, rRMSE = 13.1%, frontal (ρ = 0.710, rRMSE = 29.6%, and transverse GRF&M (ρ = 0.826, rRMSE = 18.2%. Sensitivity analysis was performed on the effect of the cut-off frequency used in the filtering of the input kinematics, as well as the threshold velocities for the gait event detection algorithm. This study was the first to use only inertial motion capture to estimate 3D GRF&M during gait, providing comparable accuracy with optical motion capture prediction. This approach enables applications that require estimation of the kinetics during walking outside the gait laboratory.

  19. Ground reaction force and 3D biomechanical characteristics of walking in short-leg walkers.

    Science.gov (United States)

    Zhang, Songning; Clowers, Kurt G; Powell, Douglas

    2006-12-01

    Short-leg walking boots offer several advantages over traditional casts. However, their effects on ground reaction forces (GRF) and three-dimensional (3D) biomechanics are not fully understood. The purpose of the study was to examine 3D lower extremity kinematics and joint dynamics during walking in two different short-leg walking boots. Eleven (five females and six males) healthy subjects performed five level walking trials in each of three conditions: two testing boot conditions, Gait Walker (DeRoyal Industries, Inc.) and Equalizer (Royce Medical Co.), and one pair of laboratory shoes (Noveto, Adidas). A force platform and a 6-camera Vicon motion analysis system were used to collect GRFs and 3D kinematic data during the testing session. A one-way repeated measures analysis of variance (ANOVA) was used to evaluate selected kinematic, GRF, and joint kinetic variables (p<0.05). The results revealed that both short-leg walking boots were effective in minimizing ankle eversion and hip adduction. Neither walker increased the bimodal vertical GRF peaks typically observed in normal walking. However, they did impose a small initial peak (<1BW) earlier in the stance phase. The Gait Walker also exhibited a slightly increased vertical GRF during midstance. These characteristics may be related to the sole materials/design, the restriction of ankle movements, and/or the elevated heel heights of the tested walkers. Both walkers appeared to increase the demand on the knee extensors while they decreased the demand of the knee and hip abductors based on the joint kinetic results.

  20. Effects of Different Lifting Cadences on Ground Reaction Forces during the Squat Exercise

    Science.gov (United States)

    Bentley, Jason R.; Amonette, William E.; Hagan, R. Donald

    2008-01-01

    The purpose of this investigation was to determine the effect of different cadences on the ground reaction force (GRF(sub R)) during the squat exercise. It is known that squats performed with greater acceleration will produce greater inertial forces; however, it is not well understood how different squat cadences affect GRF(sub R). It was hypothesized that faster squat cadences will result in greater peak GRF(sub R). METHODS: Six male subjects (30.8+/-4.4 y, 179.5+/-8.9 cm, 88.8+/-13.3 kg) with previous squat experience performed three sets of three squats using three different cadences (FC = 1 sec descent/1 sec ascent; MC = 3 sec descent/1 sec ascent; SC = 4 sec descent/2 sec ascent) with barbell mass equal to body mass. Ground reaction force was used to calculate inertial force trajectories of the body plus barbell (FI(sub system)). Forces were normalized to body mass. RESULTS: Peak GRF(sub R) and peak FI(sub system) were significantly higher in FC squats compared to MC (p=0.0002) and SC (p=0.0002). Range of GRF(sub R) and FI(sub system) were also significantly higher in FC compared to MC (psquat cadences result in significantly greater peak GRF(sub R) due to the inertia of the system. GRF(sub R) was more dependent upon decent cadence than on ascent cadence. PRACTICAL APPLICATION: This study demonstrates that faster squat cadences produce greater ground reaction forces. Therefore, the use of faster squat cadences might enhance strength and power adaptations to long-term resistance exercise training. Key Words: velocity, weight training, resistive exercise

  1. Grizzly bear (Ursus arctos horribilis) locomotion: gaits and ground reaction forces.

    Science.gov (United States)

    Shine, Catherine L; Penberthy, Skylar; Robbins, Charles T; Nelson, O Lynne; McGowan, Craig P

    2015-10-01

    Locomotion of plantigrade generalists has been relatively little studied compared with more specialised postures even though plantigrady is ancestral among quadrupeds. Bears (Ursidae) are a representative family for plantigrade carnivorans, they have the majority of the morphological characteristics identified for plantigrade species, and they have the full range of generalist behaviours. This study compared the locomotion of adult grizzly bears (Ursus arctos horribilis Linnaeus 1758), including stride parameters, gaits and analysis of three-dimensional ground reaction forces, with that of previously studied quadrupeds. At slow to moderate speeds, grizzly bears use walks, running walks and canters. Vertical ground reaction forces demonstrated the typical M-shaped curve for walks; however, this was significantly more pronounced in the hindlimb. The rate of force development was also significantly higher for the hindlimbs than for the forelimbs at all speeds. Mediolateral forces were significantly higher than would be expected for a large erect mammal, almost to the extent of a sprawling crocodilian. There may be morphological or energetic explanations for the use of the running walk rather than the trot. The high medial forces (produced from a lateral push by the animal) could be caused by frontal plane movement of the carpus and elbow by bears. Overall, while grizzly bears share some similarities with large cursorial species, their locomotor kinetics have unique characteristics. Additional studies are needed to determine whether these characters are a feature of all bears or plantigrade species. © 2015. Published by The Company of Biologists Ltd.

  2. MD1405: Demonstration of forced dynamic aperture measurements at injection

    CERN Document Server

    Carlier, Felix Simon; Persson, Tobias Hakan Bjorn; Tomas Garcia, Rogelio; CERN. Geneva. ATS Department

    2017-01-01

    Accurate measurements of dynamic aperture become more important for the LHC as it advances into increasingly nonlinear regimes of operations, as well as for the High Luminosity LHC where machine nonlinearities will have a significantly larger impact. Direct dynamic aperture measurements at top energy in the LHC are challenging, and conventional single kick methods are not viable. Dynamic aperture measurements under forced oscillation of AC dipoles have been proposed as s possible alternative observable. A first demonstration of forced DA measurements at injections energy is presented.

  3. Designing an experiment to measure cellular interaction forces

    Science.gov (United States)

    McAlinden, Niall; Glass, David G.; Millington, Owain R.; Wright, Amanda J.

    2013-09-01

    Optical trapping is a powerful tool in Life Science research and is becoming common place in many microscopy laboratories and facilities. The force applied by the laser beam on the trapped object can be accurately determined allowing any external forces acting on the trapped object to be deduced. We aim to design a series of experiments that use an optical trap to measure and quantify the interaction force between immune cells. In order to cause minimum perturbation to the sample we plan to directly trap T cells and remove the need to introduce exogenous beads to the sample. This poses a series of challenges and raises questions that need to be answered in order to design a set of effect end-point experiments. A typical cell is large compared to the beads normally trapped and highly non-uniform - can we reliably trap such objects and prevent them from rolling and re-orientating? In this paper we show how a spatial light modulator can produce a triple-spot trap, as opposed to a single-spot trap, giving complete control over the object's orientation and preventing it from rolling due, for example, to Brownian motion. To use an optical trap as a force transducer to measure an external force you must first have a reliably calibrated system. The optical trapping force is typically measured using either the theory of equipartition and observing the Brownian motion of the trapped object or using an escape force method, e.g. the viscous drag force method. In this paper we examine the relationship between force and displacement, as well as measuring the maximum displacement from equilibrium position before an object falls out of the trap, hence determining the conditions under which the different calibration methods should be applied.

  4. On the relationship between lower extremity muscles activation and peak vertical and posterior ground reaction forces during single leg drop landing.

    Science.gov (United States)

    Mahaki, M; Mi'mar, R; Mahaki, B

    2015-10-01

    Anterior cruciate ligament (ACL) injury continues to be an important medical issue for athletes participating in sports. Vertical and posterior ground reaction forces have received considerable attention for their potential influence on ACL injuries. The purpose of this study was to examine the relationship between electromyographic activity of lower extremity muscles and the peak vertical and posterior ground reaction forces during single leg drop landing. Thirteen physical education male students participated in this correlation study. Electromyographic activities of gluteus medius, biceps femoris, medial gastrocnemius, soleus as well as anterior tibialis muscles along with ground reaction forces were measured. Participants performed single-leg landing from a 0.3 m height on to a force platform. Landing was divided into two phases: 100 ms preceding ground contact and 100 ms proceeding ground contact. Pearson correlation test was used to determine the relationships between these muscles activity and peak vertical and posterior ground reaction forces. The results of the study indicated that the activity of soleus and tibialis anterior in pre-landing phase were positively correlated with peak vertical ground reaction force ([P≤0.04], [P≤0.008], respectively). However, no significant correlation was found between the activities of other muscles in pre-landing phase and peak vertical as well as peak posterior ground reaction forces. Also, no significant correlation was found between the activities of muscles in post-landing phase and peak vertical as well as peak posterior ground reaction forces. Soleus loading shifts the proximal tibia posterior at the knee joint and tibialis anterior prevent hyperporonation of the ankle, a mechanisms of ACL injury. Hence, neuromuscular training promoting preparatory muscle activity in these muscles may reduce the incidence of ACL injuries.

  5. Multi-body simulation of a canine hind limb: model development, experimental validation and calculation of ground reaction forces

    Directory of Open Access Journals (Sweden)

    Wefstaedt Patrick

    2009-11-01

    Full Text Available Abstract Background Among other causes the long-term result of hip prostheses in dogs is determined by aseptic loosening. A prevention of prosthesis complications can be achieved by an optimization of the tribological system which finally results in improved implant duration. In this context a computerized model for the calculation of hip joint loadings during different motions would be of benefit. In a first step in the development of such an inverse dynamic multi-body simulation (MBS- model we here present the setup of a canine hind limb model applicable for the calculation of ground reaction forces. Methods The anatomical geometries of the MBS-model have been established using computer tomography- (CT- and magnetic resonance imaging- (MRI- data. The CT-data were collected from the pelvis, femora, tibiae and pads of a mixed-breed adult dog. Geometric information about 22 muscles of the pelvic extremity of 4 mixed-breed adult dogs was determined using MRI. Kinematic and kinetic data obtained by motion analysis of a clinically healthy dog during a gait cycle (1 m/s on an instrumented treadmill were used to drive the model in the multi-body simulation. Results and Discussion As a result the vertical ground reaction forces (z-direction calculated by the MBS-system show a maximum deviation of 1.75%BW for the left and 4.65%BW for the right hind limb from the treadmill measurements. The calculated peak ground reaction forces in z- and y-direction were found to be comparable to the treadmill measurements, whereas the curve characteristics of the forces in y-direction were not in complete alignment. Conclusion In conclusion, it could be demonstrated that the developed MBS-model is suitable for simulating ground reaction forces of dogs during walking. In forthcoming investigations the model will be developed further for the calculation of forces and moments acting on the hip joint during different movements, which can be of help in context with the in

  6. Numerical verification of B-WIM system using reaction force signals

    International Nuclear Information System (INIS)

    Chang, Sung Jin; Kim, Nam Sik

    2012-01-01

    Bridges are ones of fundamental facilities for roads which become social overhead capital facilities and they are designed to get safety in their life cycles. However as time passes, bridge can be damaged by changes of external force and traffic environments. Therefore, a bridge should be repaired and maintained for extending its life cycle. The working load on a bridge is one of the most important factors for safety, it should be calculated accurately. The most important load among working loads is live load by a vehicle. Thus, the travel characteristics and weight of vehicle can be useful for bridge maintenance if they were estimated with high reliability. In this study, a B-WIM system in which the bridge is used for a scale have been developed for measuring the vehicle loads without the vehicle stop. The vehicle loads can be estimated by the developed B-WIM system with the reaction responses from the supporting points. The algorithm of developed B-WIM system have been verified by numerical analysis

  7. Dynamic steering beams for efficient force measurement in optical manipulation

    Institute of Scientific and Technical Information of China (English)

    Xiaocong Yuan; Yuquan Zhang; Rui Cao; Xing Zhao; Jing Bu; Siwei Zhu

    2011-01-01

    @@ An efficient and inexpensive method that uses a glass plate mounted onto a motorized rotating stage as a beam-steering device for the generation of dynamic optical traps is reported.Force analysis reveals that there are drag and trapping forces imposed on the bead in the opposite directions, respectively, in a viscous medium.The trapped bead will be rotated following the beam's motion before it reaches the critical escape velocity when the drag force is equal to the optical trapping force.The equilibrium condition facilitates the experimental measurement of the drag force with potential extensions to the determination of the viscosity of the medium or the refractive index of the bead.The proposed technique can easily be integrated into conventional optical microscopic systems with minimum modifications.%An efficient and inexpensive method that uses a glass plate mounted onto a motorized rotating stage as a beam-steering device for the generation of dynamic optical traps is reported. Force analysis reveals that there are drag and trapping forces imposed on the bead in the opposite directions, respectively, in a viscous medium. The trapped bead will be rotated following the beam's motion before it reaches the critical escape velocity when the drag force is equal to the optical trapping force. The equilibrium condition facilitates the experimental measurement of the drag force with potential extensions to the determination of the viscosity of the medium or the refractive index of the bead. The proposed technique can easily be integrated into conventional optical microscopic systems with minimum modifications.

  8. Support force measures of midsized men in seated positions.

    Science.gov (United States)

    Bush, Tamara Reid; Hubbard, Robert P

    2007-02-01

    Two areas not well researched in the field of seating mechanics are the distribution of normal and shear forces, and how those forces change with seat position. The availability of these data would be beneficial for the design and development of office, automotive and medical seats. To increase our knowledge in the area of seating mechanics, this study sought to measure the normal and shear loads applied to segmental supports in 12 seated positions, utilizing three inclination angles and four levels of seat back articulation that were associated with automotive driving positions. Force data from six regions, including the thorax, sacral region, buttocks, thighs, feet, and hand support were gathered using multi-axis load cells. The sample contained 23 midsized subjects with an average weight of 76.7 kg and a standard deviation of 4.2 kg, and an average height of 1745 mm with a standard deviation of 19 mm. Results were examined in terms of seat back inclination and in terms of torso articulation for relationships between seat positions and support forces. Using a repeated measures analysis, significant differences (p<0.05) were identified for normal forces relative to all inclination angles except for forces occurring at the hand support. Other significant differences were observed between normal forces behind the buttocks, pelvis, and feet for torso articulations. Significant differences in the shear forces occurred under the buttocks and posterior pelvis during changes in seat back inclination. Significant differences in shear forces were also identified for torso articulations. These data suggest that as seat back inclination or torso articulation change, significant shifts in force distribution occur.

  9. Fiber optic micro sensor for the measurement of tendon forces

    Directory of Open Access Journals (Sweden)

    Behrmann Gregory P

    2012-10-01

    Full Text Available Abstract A fiber optic sensor developed for the measurement of tendon forces was designed, numerically modeled, fabricated, and experimentally evaluated. The sensor incorporated fiber Bragg gratings and micro-fabricated stainless steel housings. A fiber Bragg grating is an optical device that is spectrally sensitive to axial strain. Stainless steel housings were designed to convert radial forces applied to the housing into axial forces that could be sensed by the fiber Bragg grating. The metal housings were fabricated by several methods including laser micromachining, swaging, and hydroforming. Designs are presented that allow for simultaneous temperature and force measurements as well as for simultaneous resolution of multi-axis forces. The sensor was experimentally evaluated by hydrostatic loading and in vitro testing. A commercial hydraulic burst tester was used to provide uniform pressures on the sensor in order to establish the linearity, repeatability, and accuracy characteristics of the sensor. The in vitro experiments were performed in excised tendon and in a dynamic gait simulator to simulate biological conditions. In both experimental conditions, the sensor was found to be a sensitive and reliable method for acquiring minimally invasive measurements of soft tissue forces. Our results suggest that this sensor will prove useful in a variety of biomechanical measurements.

  10. Fiber optic micro sensor for the measurement of tendon forces.

    Science.gov (United States)

    Behrmann, Gregory P; Hidler, Joseph; Mirotznik, Mark S

    2012-10-03

    A fiber optic sensor developed for the measurement of tendon forces was designed, numerically modeled, fabricated, and experimentally evaluated. The sensor incorporated fiber Bragg gratings and micro-fabricated stainless steel housings. A fiber Bragg grating is an optical device that is spectrally sensitive to axial strain. Stainless steel housings were designed to convert radial forces applied to the housing into axial forces that could be sensed by the fiber Bragg grating. The metal housings were fabricated by several methods including laser micromachining, swaging, and hydroforming. Designs are presented that allow for simultaneous temperature and force measurements as well as for simultaneous resolution of multi-axis forces.The sensor was experimentally evaluated by hydrostatic loading and in vitro testing. A commercial hydraulic burst tester was used to provide uniform pressures on the sensor in order to establish the linearity, repeatability, and accuracy characteristics of the sensor. The in vitro experiments were performed in excised tendon and in a dynamic gait simulator to simulate biological conditions. In both experimental conditions, the sensor was found to be a sensitive and reliable method for acquiring minimally invasive measurements of soft tissue forces. Our results suggest that this sensor will prove useful in a variety of biomechanical measurements.

  11. Does shoe heel design influence ground reaction forces and knee moments during maximum lunges in elite and intermediate badminton players?

    Science.gov (United States)

    Lam, Wing-Kai; Ryue, Jaejin; Lee, Ki-Kwang; Park, Sang-Kyoon; Cheung, Jason Tak-Man; Ryu, Jiseon

    2017-01-01

    Lunge is one frequently executed movement in badminton and involves a unique sagittal footstrike angle of more than 40 degrees at initial ground contact compared with other manoeuvres. This study examined if the shoe heel curvature design of a badminton shoe would influence shoe-ground kinematics, ground reaction forces, and knee moments during lunge. Eleven elite and fifteen intermediate players performed five left-forward maximum lunge trials with Rounded Heel Shoe (RHS), Flattened Heel Shoe (FHS), and Standard Heel Shoes (SHS). Shoe-ground kinematics, ground reaction forces, and knee moments were measured by using synchronized force platform and motion analysis system. A 2 (Group) x 3 (Shoe) ANOVA with repeated measures was performed to determine the effects of different shoes and different playing levels, as well as the interaction of two factors on all variables. Shoe effect indicated that players demonstrated lower maximum vertical loading rate in RHS than the other two shoes (P badminton lunge. The differences in impact loads and knee moments between elite and intermediate players may be useful in optimizing footwear design and training strategy to minimize the potential risks for impact related injuries in badminton.

  12. Bone strength estimates relative to vertical ground reaction force discriminates women runners with stress fracture history.

    Science.gov (United States)

    Popp, Kristin L; McDermott, William; Hughes, Julie M; Baxter, Stephanie A; Stovitz, Steven D; Petit, Moira A

    2017-01-01

    To determine differences in bone geometry, estimates of bone strength, muscle size and bone strength relative to load, in women runners with and without a history of stress fracture. We recruited 32 competitive distance runners aged 18-35, with (SFX, n=16) or without (NSFX, n=16) a history of stress fracture for this case-control study. Peripheral quantitative computed tomography (pQCT) was used to assess volumetric bone mineral density (vBMD, mg/mm 3 ), total (ToA) and cortical (CtA) bone areas (mm 2 ), and estimated compressive bone strength (bone strength index; BSI, mg/mm 4 ) at the distal tibia. ToA, CtA, cortical vBMD, and estimated strength (section modulus; Zp, mm 3 and strength strain index; SSIp, mm 3 ) were measured at six cortical sites along the tibia. Mean active peak vertical (pkZ) ground reaction forces (GRFs), assessed from a fatigue run on an instrumented treadmill, were used in conjunction with pQCT measurements to estimate bone strength relative to load (mm 2 /N∗kg -1 ) at all cortical sites. SSIp and Zp were 9-11% lower in the SFX group at mid-shaft of the tibia, while ToA and vBMD did not differ between groups at any measurement site. The SFX group had 11-17% lower bone strength relative to mean pkZ GRFs (phistory of stress fracture. Bone strength relative to load is also lower in this same region suggesting that strength deficits in the middle 1/3 of the tibia and altered gait biomechanics may predispose an individual to stress fracture. Copyright © 2016. Published by Elsevier Inc.

  13. Bilateral contact ground reaction forces and contact times during plyometric drop jumping.

    Science.gov (United States)

    Ball, Nick B; Stock, Christopher G; Scurr, Joanna C

    2010-10-01

    Drop jumping (DJ) is used in training programs aimed to improve lower extremity explosive power. When performing double-leg drop jumps, it is important to provide an equal stimulus to both legs to ensure balanced development of the lower legs. The aim of this study was to bilaterally analyze the ground reactions forces and temporal components of drop jumping from 3 heights. Ten recreationally active male subjects completed 3 bounce-drop jumps from 3 starting heights (0.2, 0.4, and 0.6 m). Two linked force platforms were used to record left- and right-leg peak vertical force, time to peak force, average force, ground contact time, impulse and time differential. Between-height and between-leg comparisons for each variable were made using a multivariate analysis of variance with post hoc Wilcoxon tests (p < 0.05). Results indicated that force and time variables increased as drop jump height increased (p < 0.0001). Post hoc analyses showed that at 0.2- and 0.4-m bilateral differences were present in the time to peak force, average force, and impulse. No bilateral differences for any variables were shown at 0.6-m starting height. The contact time for all jumps was <0.26 seconds. At 0.2 m, only 63% of the subjects had a starting time differential of <0.01 seconds, rising to 96.3% at 0.6 m. The results indicated that 0.6 m is the suggested drop jump height to ensure that no bilateral differences in vertical forces and temporal components occur; however, shorter contact times were found at the lower heights.

  14. Measurement and analysis of $\\alpha$ particle induced reactions on yttrium

    CERN Document Server

    Singh, N L; Chintalapudi, S N

    2000-01-01

    Excitation functions for /sup 89/Y[( alpha ,3n); ( alpha ,4n); ( alpha , p3n); ( alpha , alpha n); ( alpha , alpha 2n)] reactions were measured up to 50 MeV using stacked foil activation technique and HPGe gamma ray spectroscopy method. The experimental data were compared with calculations considering equilibrium as well as preequilibrium reactions according to the hybrid model of Blann (ALICE/90). For ( alpha , xnyp) type of reactions, the precompound contributions are described by the model. There seems to be indications of direct inelastic scattering effects in ( alpha , alpha xn) type of reactions. To the best of our knowledge, the excitation functions for ( alpha ,4n), ( alpha , p3n), ( alpha , alpha n) and ( alpha , alpha 2n) reactions were measured for the first time. (23 refs).

  15. Measurement and analysis of alpha particle induced reactions on yttrium

    Energy Technology Data Exchange (ETDEWEB)

    Singh, N.L.; Gadkari, M.S. [Baroda Univ. (India). Dept. of Physics; Chintalapudi, S.N. [IUC-DAEF Calcutta Centre, Calcutta (India)

    2000-05-01

    Excitation functions for {sup 89}Y[({alpha},3n);({alpha},4n);({alpha},p3n);({alpha},{alpha}n);({alpha},{alpha}2n)] reactions were measured up to 50 MeV using stacked foil activation technique and HPGe gamma ray spectroscopy method. The experimental data were compared with calculations considering equilibrium as well as preequilibrium reactions according to the hybrid model of Blann (ALICE/90). For ({alpha},xnyp) type of reactions, the precompound contributions are described by the model. There seems to be indications of direct inelastic scattering effects in ({alpha},{alpha}xn) type of reactions. To the best of our knowledge, the excitation functions for ({alpha},4n), ({alpha},p3n), ({alpha},{alpha}n) and ({alpha},{alpha}2n) reactions were measured for the first time. (orig.)

  16. Magnetic moment measurement of magnetic nanoparticles using atomic force microscopy

    International Nuclear Information System (INIS)

    Park, J-W; Lee, E-C; Ju, H; Yoo, I S; Chang, W-S; Chung, B H; Kim, B S

    2008-01-01

    Magnetic moment per unit mass of magnetic nanoparticles was found by using the atomic force microscope (AFM). The mass of the nanoparticles was acquired from the resonance frequency shift of the particle-attached AFM probe and magnetic force measurement was also carried out with the AFM. Combining with magnetic field strength, the magnetic moment per unit mass of the nanoparticles was determined as a function of magnetic field strength. (technical design note)

  17. A method for measuring light ion reaction cross-sections

    International Nuclear Information System (INIS)

    Carlson, R.F.; Ingemarsson, A.; Lantz, M.; Arendse, G.J.; Auce, A.; Cox, A.J.; Foertsch, S.V.; Jacobs, N.M.; Johansson, R.; Nyberg, J.; Peavy, J.; Renberg, P.-U.; Sundberg, O.; Stander, J.A.; Steyn, G.F.; Tibell, G.; Zorro, R.

    2005-01-01

    An experimental procedure for measuring reaction cross-sections of light ions in the energy range 20-50 MeV/nucleon, using a modified attenuation technique, is described. The detection method incorporates a forward detector that simultaneously measures the reaction cross-sections for five different sizes of the solid angle in steps from 99.1% to 99.8% of the total solid angle. The final reaction cross-section values are obtained by extrapolation to the full solid angle

  18. Field measurement of basal forces generated by erosive debris flows

    Science.gov (United States)

    McCoy, S.W.; Tucker, G.E.; Kean, J.W.; Coe, J.A.

    2013-01-01

    It has been proposed that debris flows cut bedrock valleys in steeplands worldwide, but field measurements needed to constrain mechanistic models of this process remain sparse due to the difficulty of instrumenting natural flows. Here we present and analyze measurements made using an automated sensor network, erosion bolts, and a 15.24 cm by 15.24 cm force plate installed in the bedrock channel floor of a steep catchment. These measurements allow us to quantify the distribution of basal forces from natural debris‒flow events that incised bedrock. Over the 4 year monitoring period, 11 debris‒flow events scoured the bedrock channel floor. No clear water flows were observed. Measurements of erosion bolts at the beginning and end of the study indicated that the bedrock channel floor was lowered by 36 to 64 mm. The basal force during these erosive debris‒flow events had a large‒magnitude (up to 21 kN, which was approximately 50 times larger than the concurrent time‒averaged mean force), high‒frequency (greater than 1 Hz) fluctuating component. We interpret these fluctuations as flow particles impacting the bed. The resulting variability in force magnitude increased linearly with the time‒averaged mean basal force. Probability density functions of basal normal forces were consistent with a generalized Pareto distribution, rather than the exponential distribution that is commonly found in experimental and simulated monodispersed granular flows and which has a lower probability of large forces. When the bed sediment thickness covering the force plate was greater than ~ 20 times the median bed sediment grain size, no significant fluctuations about the time‒averaged mean force were measured, indicating that a thin layer of sediment (~ 5 cm in the monitored cases) can effectively shield the subjacent bed from erosive impacts. Coarse‒grained granular surges and water‒rich, intersurge flow had very similar basal force distributions despite

  19. Generating Converged Accurate Free Energy Surfaces for Chemical Reactions with a Force-Matched Semiempirical Model.

    Science.gov (United States)

    Kroonblawd, Matthew P; Pietrucci, Fabio; Saitta, Antonino Marco; Goldman, Nir

    2018-04-10

    We demonstrate the capability of creating robust density functional tight binding (DFTB) models for chemical reactivity in prebiotic mixtures through force matching to short time scale quantum free energy estimates. Molecular dynamics using density functional theory (DFT) is a highly accurate approach to generate free energy surfaces for chemical reactions, but the extreme computational cost often limits the time scales and range of thermodynamic states that can feasibly be studied. In contrast, DFTB is a semiempirical quantum method that affords up to a thousandfold reduction in cost and can recover DFT-level accuracy. Here, we show that a force-matched DFTB model for aqueous glycine condensation reactions yields free energy surfaces that are consistent with experimental observations of reaction energetics. Convergence analysis reveals that multiple nanoseconds of combined trajectory are needed to reach a steady-fluctuating free energy estimate for glycine condensation. Predictive accuracy of force-matched DFTB is demonstrated by direct comparison to DFT, with the two approaches yielding surfaces with large regions that differ by only a few kcal mol -1 .

  20. Cantilever contribution to the total electrostatic force measured with the atomic force microscope

    International Nuclear Information System (INIS)

    Guriyanova, Svetlana; Golovko, Dmytro S; Bonaccurso, Elmar

    2010-01-01

    The atomic force microscope (AFM) is a powerful tool for surface imaging at the nanometer scale and surface force measurements in the piconewton range. Among long-range surface forces, the electrostatic forces play a predominant role. They originate if the electric potentials of the substrate and of the tip of the AFM cantilever are different. A quantitative interpretation of the AFM signal is often difficult because it depends in a complicated fashion on the cantilever–tip–surface geometry. Since the electrostatic interaction is a long-range interaction, the cantilever, which is many microns from the surface, contributes to the total electrostatic force along with the tip. Here we present results of the electrostatic interaction between a conducting flat surface and horizontal or tilted cantilevers, with and without tips, at various distances from the surface. As addressed in a previous work, we show that the contribution of the cantilever to the overall force cannot be neglected. Based on a predictive model and on 3D confocal measurements, we discuss the influence of the tilting angle of the cantilever

  1. Accurate fluid force measurement based on control surface integration

    Science.gov (United States)

    Lentink, David

    2018-01-01

    Nonintrusive 3D fluid force measurements are still challenging to conduct accurately for freely moving animals, vehicles, and deforming objects. Two techniques, 3D particle image velocimetry (PIV) and a new technique, the aerodynamic force platform (AFP), address this. Both rely on the control volume integral for momentum; whereas PIV requires numerical integration of flow fields, the AFP performs the integration mechanically based on rigid walls that form the control surface. The accuracy of both PIV and AFP measurements based on the control surface integration is thought to hinge on determining the unsteady body force associated with the acceleration of the volume of displaced fluid. Here, I introduce a set of non-dimensional error ratios to show which fluid and body parameters make the error negligible. The unsteady body force is insignificant in all conditions where the average density of the body is much greater than the density of the fluid, e.g., in gas. Whenever a strongly deforming body experiences significant buoyancy and acceleration, the error is significant. Remarkably, this error can be entirely corrected for with an exact factor provided that the body has a sufficiently homogenous density or acceleration distribution, which is common in liquids. The correction factor for omitting the unsteady body force, {{{ {ρ f}} {1 - {ρ f} ( {{ρ b}+{ρ f}} )}.{( {{{{ρ }}b}+{ρ f}} )}}} , depends only on the fluid, {ρ f}, and body, {{ρ }}b, density. Whereas these straightforward solutions work even at the liquid-gas interface in a significant number of cases, they do not work for generalized bodies undergoing buoyancy in combination with appreciable body density inhomogeneity, volume change (PIV), or volume rate-of-change (PIV and AFP). In these less common cases, the 3D body shape needs to be measured and resolved in time and space to estimate the unsteady body force. The analysis shows that accounting for the unsteady body force is straightforward to non

  2. Ground reaction forces and kinematics in distance running in older-aged men.

    Science.gov (United States)

    Bus, Sicco A

    2003-07-01

    The biomechanics of distance running has not been studied before in older-aged runners but may be different than in younger-aged runners because of musculoskeletal degeneration at older age. This study aimed at determining whether the stance phase kinematics and ground reaction forces in running are different between younger- and older-aged men. Lower-extremity kinematics using three-dimensional motion analysis and ground reaction forces (GRF) using a force plate were assessed in 16 older-aged (55-65 yr) and 13 younger-aged (20-35 yr) well-trained male distance runners running at a self-selected (SRS) and a controlled (CRS) speed of 3.3 m.s-1. The older subjects ran at significantly lower self-selected speeds than the younger subjects (mean 3.34 vs 3.77 m.s-1). In both speed conditions, the older runners exhibited significantly more knee flexion at heel strike and significantly less knee flexion and extension range of motion. No age group differences were present in subtalar joint motion. Impact peak force (1.91 vs 1.70 BW) and maximal initial loading rate (107.5 vs 85.5 BW.s-1) were significantly higher in the older runners at the CRS. Maximal peak vertical and anteroposterior forces and impulses were significantly lower in the older runners at the SRS. The biomechanics of running is different between older- and younger-aged runners on several relevant parameters. The larger impact peak force and initial loading rate indicate a loss of shock-absorbing capacity in the older runners. This may increase their susceptibility to lower-extremity overuse injuries. Moreover, it emphasizes the focus on optimizing cushioning properties in the design and prescription of running shoes and suggests that older-aged runners should be cautious with running under conditions of high impact.

  3. The application of force-sensing resistor sensors for measuring forces developed by the human hand.

    Science.gov (United States)

    Nikonovas, A; Harrison, A J L; Hoult, S; Sammut, D

    2004-01-01

    Most attempts to measure forces developed by the human hand have been implemented by placing force sensors on the object of interaction. Other researchers have placed sensors just on the subject's fingertips. In this paper, a system is described that measures forces over the entire hand using thin-film sensors and associated electronics. This system was developed by the authors and is able to obtain force readings from up to 60 thin-film sensors at rates of up to 400 samples/s per sensor. The sensors can be placed anywhere on the palm and/or fingers of the hand. The sensor readings, together with a video stream containing information about hand posture, are logged into a portable computer using a multiplexer, analogue-to-digital converter and software developed for the purpose. The system has been successfully used to measure forces involved in a range of everyday tasks such as driving a vehicle, lifting saucepans and hitting a golf ball. In the latter case, results are compared with those from an instrumented golf club. Future applications include the assessment of hand strength following disease, trauma or surgery, and to enable quantitative ergonomic investigations.

  4. Capillary force on a tilted cylinder: Atomic Force Microscope (AFM) measurements.

    Science.gov (United States)

    Kosgodagan Acharige, Sébastien; Laurent, Justine; Steinberger, Audrey

    2017-11-01

    The capillary force in situations where the liquid meniscus is asymmetric, such as the one around a tilted object, has been hitherto barely investigated even though these situations are very common in practice. In particular, the capillary force exerted on a tilted object may depend on the dipping angle i. We investigate experimentally the capillary force that applies on a tilted cylinder as a function of its dipping angle i, using a home-built tilting Atomic Force Microscope (AFM) with custom made probes. A micrometric-size rod is glued at the end of an AFM cantilever of known stiffness, whose deflection is measured when the cylindrical probe is dipped in and retracted from reference liquids. We show that a torque correction is necessary to understand the measured deflection. We give the explicit expression of this correction as a function of the probes' geometrical parameters, so that its magnitude can be readily evaluated. The results are compatible with a vertical capillary force varying as 1/cosi, in agreement with a recent theoretical prediction. Finally, we discuss the accuracy of the method for measuring the surface tension times the cosine of the contact angle of the liquid on the probe. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Measured long-range repulsive Casimir–Lifshitz forces

    Science.gov (United States)

    Munday, J. N.; Capasso, Federico; Parsegian, V. Adrian

    2014-01-01

    Quantum fluctuations create intermolecular forces that pervade macroscopic bodies1–3. At molecular separations of a few nanometres or less, these interactions are the familiar van der Waals forces4. However, as recognized in the theories of Casimir, Polder and Lifshitz5–7, at larger distances and between macroscopic condensed media they reveal retardation effects associated with the finite speed of light. Although these long-range forces exist within all matter, only attractive interactions have so far been measured between material bodies8–11. Here we show experimentally that, in accord with theoretical prediction12, the sign of the force can be changed from attractive to repulsive by suitable choice of interacting materials immersed in a fluid. The measured repulsive interaction is found to be weaker than the attractive. However, in both cases the magnitude of the force increases with decreasing surface separation. Repulsive Casimir–Lifshitz forces could allow quantum levitation of objects in a fluid and lead to a new class of switchable nanoscale devices with ultra-low static friction13–15. PMID:19129843

  6. Measured long-range repulsive Casimir-Lifshitz forces.

    Science.gov (United States)

    Munday, J N; Capasso, Federico; Parsegian, V Adrian

    2009-01-08

    Quantum fluctuations create intermolecular forces that pervade macroscopic bodies. At molecular separations of a few nanometres or less, these interactions are the familiar van der Waals forces. However, as recognized in the theories of Casimir, Polder and Lifshitz, at larger distances and between macroscopic condensed media they reveal retardation effects associated with the finite speed of light. Although these long-range forces exist within all matter, only attractive interactions have so far been measured between material bodies. Here we show experimentally that, in accord with theoretical prediction, the sign of the force can be changed from attractive to repulsive by suitable choice of interacting materials immersed in a fluid. The measured repulsive interaction is found to be weaker than the attractive. However, in both cases the magnitude of the force increases with decreasing surface separation. Repulsive Casimir-Lifshitz forces could allow quantum levitation of objects in a fluid and lead to a new class of switchable nanoscale devices with ultra-low static friction.

  7. WP/084 Measuring Industry Agglomeration and Identifying the Driving Forces

    DEFF Research Database (Denmark)

    Howard, Emma; Tarp, Finn; Newman, Carol

    Understanding industry agglomeration and its driving forces is critical for the formulation of industrial policy in developing countries. Crucial to this process is the definition and measurement of agglomeration. We propose a new measure and examine what it reveals about the importance of transp......Understanding industry agglomeration and its driving forces is critical for the formulation of industrial policy in developing countries. Crucial to this process is the definition and measurement of agglomeration. We propose a new measure and examine what it reveals about the importance...... of transport costs, labour market pooling, and technology transfer for agglomeration processes. We contrast this analysis with insights from existing measures in the literature and find very different underlying stories at work. An exceptionally rich set of data from Vietnam makes us confident that our measure...

  8. Design rules for biomolecular adhesion: lessons from force measurements.

    Science.gov (United States)

    Leckband, Deborah

    2010-01-01

    Cell adhesion to matrix, other cells, or pathogens plays a pivotal role in many processes in biomolecular engineering. Early macroscopic methods of quantifying adhesion led to the development of quantitative models of cell adhesion and migration. The more recent use of sensitive probes to quantify the forces that alter or manipulate adhesion proteins has revealed much greater functional diversity than was apparent from population average measurements of cell adhesion. This review highlights theoretical and experimental methods that identified force-dependent molecular properties that are central to the biological activity of adhesion proteins. Experimental and theoretical methods emphasized in this review include the surface force apparatus, atomic force microscopy, and vesicle-based probes. Specific examples given illustrate how these tools have revealed unique properties of adhesion proteins and their structural origins.

  9. Reducing detrimental electrostatic effects in Casimir-force measurements and Casimir-force-based microdevices

    Science.gov (United States)

    Xu, Jun; Klimchitskaya, G. L.; Mostepanenko, V. M.; Mohideen, U.

    2018-03-01

    It is well known that residual electrostatic forces create significant difficulties in precise measurements of the Casimir force and the wide use of Casimir-operated microdevices. We experimentally demonstrate that, with the help of Ar-ion cleaning of the surfaces, it is possible to make electrostatic effects negligibly small compared to the Casimir interaction. Our experimental setup consists of a dynamic atomic force microscope supplemented with an Ar-ion gun and argon reservoir. The residual potential difference between the Au-coated surfaces of a sphere and those of a plate was measured both before and after in situ Ar-ion cleaning. It is shown that this cleaning decreases the magnitude of the residual potential by up to an order of magnitude and makes it almost independent of the separation. The gradient of the Casimir force was measured using ordinary samples subjected to Ar-ion cleaning. The obtained results are shown to be in good agreement both with previous precision measurements using specially selected samples and with theoretical predictions of the Lifshitz theory. The conclusion is made that the suggested method of in situ Ar-ion cleaning is effective in reducing the electrostatic effects and therefore is a great resource for experiments on measuring the Casimir interaction and for Casimir-operated microdevices.

  10. Measuring Industry Coagglomeration and Identifying the Driving Forces

    DEFF Research Database (Denmark)

    Howard, Emma; Newman, Carol; Tarp, Finn

    2015-01-01

    Understanding industry agglomeration and its driving forces is critical for the formulation of industrial policy in developing countries. Crucial to this process is the definition and measurement of agglomeration. We construct a new coagglomeration index based purely on the location of firms. We...... underlying stories at work. We conclude that in conducting analyses of this kind giving consideration to the source of agglomeration economies, employees or entrepreneurs, and finding an appropriate measure for agglomeration, are both crucial to the process of identifying agglomerative forces....

  11. Identification of GMS friction model without friction force measurement

    International Nuclear Information System (INIS)

    Grami, Said; Aissaoui, Hicham

    2011-01-01

    This paper deals with an online identification of the Generalized Maxwell Slip (GMS) friction model for both presliding and sliding regime at the same time. This identification is based on robust adaptive observer without friction force measurement. To apply the observer, a new approach of calculating the filtered friction force from the measurable signals is introduced. Moreover, two approximations are proposed to get the friction model linear over the unknown parameters and an approach of suitable filtering is introduced to guarantee the continuity of the model. Simulation results are presented to prove the efficiency of the approach of identification.

  12. Measuring of beat up force on weaving machines

    Directory of Open Access Journals (Sweden)

    Bílek Martin

    2017-01-01

    Full Text Available The textile material (warp is stressed cyclically at a relative high frequency during the weaving process. Therefore, the special measuring device for analysis of beat up force in the textile material during the weaving process, has been devised in the Weaving Laboratory of the TUL. This paper includes a description of this measuring device. The experimental part includes measurements results for various materials (PES and VS and various warp thread densities of the produced fabric.

  13. Force and Compliance Measurements on Living Cells Using Atomic Force Microscopy (AFM

    Directory of Open Access Journals (Sweden)

    Wojcikiewicz Ewa P.

    2004-01-01

    Full Text Available We describe the use of atomic force microscopy (AFM in studies of cell adhesion and cell compliance. Our studies use the interaction between leukocyte function associated antigen-1 (LFA-1/intercellular adhesion molecule-1 (ICAM-1 as a model system. The forces required to unbind a single LFA-1/ICAM-1 bond were measured at different loading rates. This data was used to determine the dynamic strength of the LFA-1/ICAM-1 complex and characterize the activation potential that this complex overcomes during its breakage. Force measurements acquired at the multiple- bond level provided insight about the mechanism of cell adhesion. In addition, the AFM was used as a microindenter to determine the mechanical properties of cells. The applications of these methods are described using data from a previous study.

  14. Criteria of reaction identification and selection of badly measured events

    International Nuclear Information System (INIS)

    Linetskij, A.R.; Lyubarskij, G.Ya.; Sagalovich, N.E.

    1979-01-01

    Basing on photoemulsion methods of studying channels of multiparticle nuclear reactions the metrological characteristics of a physical technique are described in the process of its development. To increase the accuracy of reaction identification the technique for picture measuring has been complicated by introducing calibration measurements of tracks of stopped in the emulsion primary α-particles. Callibration measurements have support assumptions on energy oscillations of the primary beam and made possible the employment of actual values of this energy instead of rated one during mathematical processing. By using simulation reactions the effect of errors in determining the contraction ratio has been estimated. It has been found that rather a small error in determining the contraction (+-20%) results in additional casting-out 8-15% of measured events

  15. Integrated pressure-force-kinematics measuring system for the characterisation of plantar foot loading during locomotion.

    Science.gov (United States)

    Giacomozzi, C; Macellari, V; Leardini, A; Benedetti, M G

    2000-03-01

    Plantar pressure, ground reaction force and body-segment kinematics measurements are largely used in gait analysis to characterise normal and abnormal function of the human foot. The combination of all these data together provides a more exhaustive, detailed and accurate view of foot loading during activities than traditional measurement systems alone do. A prototype system is presented that integrates a pressure platform, a force platform and a 3D anatomical tracking system to acquire combined information about foot function and loading. A stereophotogrammetric system and an anatomically based protocol for foot segment kinematics is included in a previously devised piezo-dynamometric system that combines pressure and force measurements. Experimental validation tests are carried out to check for both spatial and time synchronisation. Misalignment of the three systems is found to be within 6.0, 5.0 and 1.5 mm for the stereophotogrammetric system, force platform and pressure platform, respectively. The combination of position and pressure data allows for a more accurate selection of plantar foot subareas on the footprint. Measurements are also taken on five healthy volunteers during level walking to verify the feasibility of the overall experimental protocol. Four main subareas are defined and identified, and the relevant vertical and shear force data are computed. The integrated system is effective when there is a need for loading measurements in specific plantar foot subareas. This is attractive both in clinical assessment and in biomechanics research.

  16. Measuring parity violation using the neutron capture reaction

    International Nuclear Information System (INIS)

    Frankle, C.M.; Bowman, J.D.; Seestrom, S.J.; Roberson, N.R.; Sharapov, E.I.

    1993-01-01

    Measuring parity violation using the total capture reaction has certain advantages over neutron transmission experiments. Very much less material is required for targets, a necessity when dealing with separated isotopes. The capture reaction is also quite sensitive to very weak resonances. These advantages indicated the need to construct a near 4π gamma ray detector for use at LANSCE. A design for such a detector has been completed. Issues influencing the design and the final design parameters will be discussed in detail

  17. Ground reaction forces in shallow water running are affected by immersion level, running speed and gender.

    Science.gov (United States)

    Haupenthal, Alessandro; Fontana, Heiliane de Brito; Ruschel, Caroline; dos Santos, Daniela Pacheco; Roesler, Helio

    2013-07-01

    To analyze the effect of depth of immersion, running speed and gender on ground reaction forces during water running. Controlled laboratory study. Twenty adults (ten male and ten female) participated by running at two levels of immersion (hip and chest) and two speed conditions (slow and fast). Data were collected using an underwater force platform. The following variables were analyzed: vertical force peak (Fy), loading rate (LR) and anterior force peak (Fx anterior). Three-factor mixed ANOVA was used to analyze data. Significant effects of immersion level, speed and gender on Fy were observed, without interaction between factors. Fy was greater when females ran fast at the hip level. There was a significant increase in LR with a reduction in the level of immersion regardless of the speed and gender. No effect of speed or gender on LR was observed. Regarding Fx anterior, significant interaction between speed and immersion level was found: in the slow condition, participants presented greater values at chest immersion, whereas, during the fast running condition, greater values were observed at hip level. The effect of gender was only significant during fast water running, with Fx anterior being greater in the men group. Increasing speed raised Fx anterior significantly irrespective of the level of immersion and gender. The magnitude of ground reaction forces during shallow water running are affected by immersion level, running speed and gender and, for this reason, these factors should be taken into account during exercise prescription. Copyright © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  18. Effect of fatigue and gender on kinematics and ground reaction forces variables in recreational runners.

    Science.gov (United States)

    Bazuelo-Ruiz, Bruno; Durá-Gil, Juan V; Palomares, Nicolás; Medina, Enrique; Llana-Belloch, Salvador

    2018-01-01

    The presence of fatigue has been shown to modify running biomechanics. Overall in terms of gender, women are at lower risk than men for sustaining running-related injuries, although it depends on the factors taken into account. One possible reason for these differences in the injury rate and location might be the dissimilar running patterns between men and women. The purpose of this study was to determine the effect of fatigue and gender on the kinematic and ground reaction forces (GRF) parameters in recreational runners. Fifty-seven participants (28 males and 29 females) had kinematic and GRF variables measured while running at speed of 3.3 m s -1 before and after a fatigue test protocol. The fatigue protocol included (1) a running Course-Navette test, (2) running up and down a flight of stairs for 5 min, and (3) performance of alternating jumps on a step (five sets of 1 minute each with 30 resting seconds between the sets). Fatigue decreased dorsiflexion (14.24 ± 4.98° in pre-fatigue and 12.65 ± 6.21° in fatigue condition, p  < 0.05) at foot strike phase in females, and plantar flexion (-19.23 ± 4.12° in pre-fatigue and -18.26 ± 5.31° in fatigue condition, p  < 0.05) at toe-off phase in males. These changes led to a decreased loading rate (88.14 ± 25.82 BW/s in pre-fatigue and 83.97 ± 18.83 BW/s in fatigue condition, p  < 0.05) and the impact peak in females (1.95 ± 0.31 BW in pre-fatigue and 1.90 ± 0.31 BW in fatigue condition, p  < 0.05), and higher peak propulsive forces in males (-0.26 ± 0.04 BW in pre-fatigue and -0.27 ± 0.05 BW in fatigue condition, p  < 0.05) in the fatigue condition. It seems that better responses to impact under a fatigue condition are observed among women. Further studies should confirm whether these changes represent a strategy to optimize shock attenuation, prevent running injuries and improve running economy.

  19. Effect of fatigue and gender on kinematics and ground reaction forces variables in recreational runners

    Directory of Open Access Journals (Sweden)

    Bruno Bazuelo-Ruiz

    2018-03-01

    Full Text Available The presence of fatigue has been shown to modify running biomechanics. Overall in terms of gender, women are at lower risk than men for sustaining running-related injuries, although it depends on the factors taken into account. One possible reason for these differences in the injury rate and location might be the dissimilar running patterns between men and women. The purpose of this study was to determine the effect of fatigue and gender on the kinematic and ground reaction forces (GRF parameters in recreational runners. Fifty-seven participants (28 males and 29 females had kinematic and GRF variables measured while running at speed of 3.3 m s−1 before and after a fatigue test protocol. The fatigue protocol included (1 a running Course-Navette test, (2 running up and down a flight of stairs for 5 min, and (3 performance of alternating jumps on a step (five sets of 1 minute each with 30 resting seconds between the sets. Fatigue decreased dorsiflexion (14.24 ± 4.98° in pre-fatigue and 12.65 ± 6.21° in fatigue condition, p < 0.05 at foot strike phase in females, and plantar flexion (−19.23 ± 4.12° in pre-fatigue and −18.26 ± 5.31° in fatigue condition, p < 0.05 at toe-off phase in males. These changes led to a decreased loading rate (88.14 ± 25.82 BW/s in pre-fatigue and 83.97 ± 18.83 BW/s in fatigue condition, p < 0.05 and the impact peak in females (1.95 ± 0.31 BW in pre-fatigue and 1.90 ± 0.31 BW in fatigue condition, p < 0.05, and higher peak propulsive forces in males (−0.26 ± 0.04 BW in pre-fatigue and −0.27 ± 0.05 BW in fatigue condition, p < 0.05 in the fatigue condition. It seems that better responses to impact under a fatigue condition are observed among women. Further studies should confirm whether these changes represent a strategy to optimize shock attenuation, prevent running injuries and improve running economy.

  20. The vertical ground reaction force and the pressure distribution on the claws of dairy cows while walking on a flat substrate

    NARCIS (Netherlands)

    Tol, van der P.P.J.; Metz, J.H.M.; Noordhuizen-Stassen, E.N.; Back, W.; Braam, C.R.; Weijs, W.A.

    2003-01-01

    The pressure distribution under the bovine claw while walking was measured to test the hypotheses that the vertical ground reaction force is unevenly distributed and makes some (regions of the) claws more prone to injuries due to overloading than others. Each limb of nine recently trimmed Holstein

  1. Force-velocity measurements of a few growing actin filaments.

    Directory of Open Access Journals (Sweden)

    Coraline Brangbour

    2011-04-01

    Full Text Available The polymerization of actin in filaments generates forces that play a pivotal role in many cellular processes. We introduce a novel technique to determine the force-velocity relation when a few independent anchored filaments grow between magnetic colloidal particles. When a magnetic field is applied, the colloidal particles assemble into chains under controlled loading or spacing. As the filaments elongate, the beads separate, allowing the force-velocity curve to be precisely measured. In the widely accepted Brownian ratchet model, the transduced force is associated with the slowing down of the on-rate polymerization. Unexpectedly, in our experiments, filaments are shown to grow at the same rate as when they are free in solution. However, as they elongate, filaments are more confined in the interspace between beads. Higher repulsive forces result from this higher confinement, which is associated with a lower entropy. In this mechanism, the production of force is not controlled by the polymerization rate, but is a consequence of the restriction of filaments' orientational fluctuations at their attachment point.

  2. Stride length: the impact on propulsion and bracing ground reaction force in overhand throwing.

    Science.gov (United States)

    Ramsey, Dan K; Crotin, Ryan L

    2018-03-26

    Propulsion and bracing ground reaction force (GRF) in overhand throwing are integral in propagating joint reaction kinetics and ball velocity, yet how stride length effects drive (hind) and stride (lead) leg GRF profiles remain unknown. Using a randomised crossover design, 19 pitchers (15 collegiate and 4 high school) were assigned to throw 2 simulated 80-pitch games at ±25% of their desired stride length. An integrated motion capture system with two force plates and radar gun tracked each throw. Vertical and anterior-posterior GRF was normalised then impulse was derived. Paired t-tests identified whether differences between conditions were significant. Late in single leg support, peak propulsion GRF was statistically greater for the drive leg with increased stride. Stride leg peak vertical GRF in braking occurred before acceleration with longer strides, but near ball release with shorter strides. Greater posterior shear GRF involving both legs demonstrated increased braking with longer strides. Conversely, decreased drive leg propulsion reduced both legs' braking effects with shorter strides. Results suggest an interconnection between normalised stride length and GRF application in propulsion and bracing. This work has shown stride length to be an important kinematic factor affecting the magnitude and timing of external forces acting upon the body.

  3. Prediction of Support Reaction Forces of ITA via Response Spectrum Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Jin Sung; Jeong, Joon Ho; Lee, Sang Jin; Oh, Jin Ho; Lee, Jong Min [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    The irradiation targets are transferred along pipes between TTS (Target Transfer Station) and ITA (Irradiation Tube Assembly) by hydraulic forces. The ITA corresponds to the vertical guide tube for irradiation targets inside a reactor, and it penetrates the reactor structure. Because the ITA is classified into seismic category II, its structural integrity must be evaluated by the seismic analysis. To approach more realistic problem, the interaction between the ITA and the reactor structure must be considered. However, this paper is focused on the preliminary analysis, and it is simplified that only the response of the ITA caused by earthquake affects the reactor structure. The response of the ITA is predicted by the spectrum response analysis based on the FDRS (Floor Design Response Spectra) of KJRR. Finally, the reaction forces corresponding to the load transfer into the reactor structure are estimated by using ANSYS. In this study, the reaction forces due to the earthquake are estimated by the response spectrum analysis. For the saving computational time and resource required, the FE model with beam element is constructed, and it is confirmed that the accuracy of the solution is acceptable by comparing the results of the solid model.

  4. Spin motive forces, 'measurements', and spin-valves

    International Nuclear Information System (INIS)

    Barnes, S.E.

    2007-01-01

    Discussed is the spin motive force (smf) produced by a spin valve, this reflecting its dynamics. Relaxation implies an implicit measurement of the magnetization of the free layer of a valve. It is shown this has implications for the angular dependence of the torque transfer. Some discussion of recent experiments is included

  5. Model Engine Performance Measurement From Force Balance Instrumentation

    Science.gov (United States)

    Jeracki, Robert J.

    1998-01-01

    A large scale model representative of a low-noise, high bypass ratio turbofan engine was tested for acoustics and performance in the NASA Lewis 9- by 15-Foot Low-Speed Wind Tunnel. This test was part of NASA's continuing Advanced Subsonic Technology Noise Reduction Program. The low tip speed fan, nacelle, and an un-powered core passage (with core inlet guide vanes) were simulated. The fan blades and hub are mounted on a rotating thrust and torque balance. The nacelle, bypass duct stators, and core passage are attached to a six component force balance. The two balance forces, when corrected for internal pressure tares, measure the total thrust-minus-drag of the engine simulator. Corrected for scaling and other effects, it is basically the same force that the engine supports would feel, operating at similar conditions. A control volume is shown and discussed, identifying the various force components of the engine simulator thrust and definitions of net thrust. Several wind tunnel runs with nearly the same hardware installed are compared, to identify the repeatability of the measured thrust-minus-drag. Other wind tunnel runs, with hardware changes that affected fan performance, are compared to the baseline configuration, and the thrust and torque effects are shown. Finally, a thrust comparison between the force balance and nozzle gross thrust methods is shown, and both yield very similar results.

  6. Enclosed Electronic System for Force Measurements in Knee Implants

    Directory of Open Access Journals (Sweden)

    David Forchelet

    2014-08-01

    Full Text Available Total knee arthroplasty is a widely performed surgical technique. Soft tissue force balancing during the operation relies strongly on the experience of the surgeon in equilibrating tension in the collateral ligaments. Little information on the forces in the implanted prosthesis is available during surgery and post-operative treatment. This paper presents the design, fabrication and testing of an instrumented insert performing force measurements in a knee prosthesis. The insert contains a closed structure composed of printed circuit boards and incorporates a microfabricated polyimide thin-film piezoresistive strain sensor for each condylar compartment. The sensor is tested in a mechanical knee simulator that mimics in-vivo conditions. For characterization purposes, static and dynamic load patterns are applied to the instrumented insert. Results show that the sensors are able to measure forces up to 1.5 times body weight with a sensitivity fitting the requirements for the proposed use. Dynamic testing of the insert shows a good tracking of slow and fast changing forces in the knee prosthesis by the sensors.

  7. Surface contact potential patches and Casimir force measurements

    International Nuclear Information System (INIS)

    Kim, W. J.; Sushkov, A. O.; Lamoreaux, S. K.; Dalvit, D. A. R.

    2010-01-01

    We present calculations of contact potential surface patch effects that simplify previous treatments. It is shown that, because of the linearity of Laplace's equation, the presence of patch potentials does not affect an electrostatic calibration of a two-plate Casimir measurement apparatus. Using models that include long-range variations in the contact potential across the plate surfaces, a number of experimental observations can be reproduced and explained. For these models, numerical calculations show that if a voltage is applied between the plates which minimizes the force, a residual electrostatic force persists, and that the minimizing potential varies with distance. The residual force can be described by a fit to a simple two-parameter function involving the minimizing potential and its variation with distance. We show the origin of this residual force by use of a simple parallel capacitor model. Finally, the implications of a residual force that varies in a manner different from 1/d on the accuracy of previous Casimir measurements is discussed.

  8. A COMPARISON OF GOLF SHOE DESIGNS HIGHLIGHTS GREATER GROUND REACTION FORCES WITH SHORTER IRONS

    Directory of Open Access Journals (Sweden)

    Paul Worsfold

    2007-12-01

    Full Text Available In an effort to reduce golf turf damage the traditional metal spike golf shoe has been redesigned, but shoe-ground biomechanical evaluations have utilised artificial grass surfaces. Twenty-four golfers wore three different golf shoe traction designs (traditional metal spikes, alternative spikes, and a flat-soled shoe with no additional traction when performing shots with a driver, 3 iron and 7 iron. Ground action forces were measured beneath the feet by two natural grass covered force platforms. The maximum vertical force recorded at the back foot with the 3 iron and 7 iron was 0.82 BW (body weight and at the front foot 1.1 BW approximately in both the metal spike and alternative spike golf shoe designs. When using the driver these maximal vertical values were 0.49 BW at the back foot and 0.84 BW at the front foot. Furthermore, as performance of the backswing and then downswing necessitates a change in movement direction the range of force generated during the complete swing was calculated. In the metal spike shoe the vertical force generated at the back foot with both irons was 0.67 BW and at the front foot 0.96 BW with the 3 iron and 0.92 BW with the 7 iron. The back foot vertical force generated with the driver was 0.33 BW and at the front foot 0.83 BW wearing the metal spike shoe. Results indicated the greater force generation with the irons. When using the driver the more horizontal swing plane associated with the longer club reduced vertical forces at the back and front foot. However, the mediolateral force generated across each foot in the metal and alternative spike shoes when using the driver was greater than when the irons were used. The coefficient of friction was 0. 62 at the back and front foot whichever shoe was worn or club used

  9. Friction of ice measured using lateral force microscopy

    International Nuclear Information System (INIS)

    Bluhm, Hendrik; Inoue, Takahito; Salmeron, Miquel

    2000-01-01

    The friction of nanometer thin ice films grown on mica substrates is investigated using atomic force microscopy (AFM). Friction was found to be of similar magnitude as the static friction of ice reported in macroscopic experiments. The possible existence of a lubricating film of water due to pressure melting, frictional heating, and surface premelting is discussed based on the experimental results using noncontact, contact, and lateral force microscopy. We conclude that AFM measures the dry friction of ice due to the low scan speed and the squeezing out of the water layer between the sharp AFM tip and the ice surface. (c) 2000 The American Physical Society

  10. Three-nucleon force contribution in the distorted-wave theory of (d ,p ) reactions

    Science.gov (United States)

    Timofeyuk, N. K.

    2018-05-01

    The distorted-wave theory of A (d ,p )B reactions, widely used to analyze experimental data, is based on a Hamiltonian that includes only two-nucleon interactions. However, numerous studies of few-nucleon systems and many modern developments in nuclear structure theory show the importance of the three-nucleon (3 N ) force. The purpose of this paper is to study the contribution of the 3 N force of the simplest possible form to the A (d ,p )B reaction amplitude. This contribution is given by a new term that accounts for the interaction of the neutron and proton in the incoming deuteron with one of the target nucleons. This term involves a new type of nuclear matrix elements containing an infinite number of target excitations in addition to the main part associated with the traditional overlap function between A and B . The nuclear matrix elements are calculated for double-closed shell targets within a mean field theory where target excitations are shown to be equivalent to exchanges between valence and core nucleons. These matrix elements can be readily incorporated into available reaction codes if the 3 N interaction has a spin-independent zero-range form. Distorted-wave calculations are presented for a contact 3 N force with the volume integral fixed by the chiral effective field theory at the next-to-next-to-leading order. For this particular choice, the 3 N contribution is noticeable, especially at high deuteron incident energies. No 3 N effects are seen for incident energies below the Coulomb barrier. The finite range can significantly affect the 3 N contribution to the (d ,p ) cross sections. Finite-range studies require new formal developments and, therefore, their contribution is preliminarily assessed within the plane-wave Born approximation, together with sensitivity to the choice of the deuteron model.

  11. Numerical simulation for aspects of homogeneous and heterogeneous reactions in forced convection flow of nanofluid

    Science.gov (United States)

    Hayat, Tasawar; Shah, Faisal; Khan, Muhammad Ijaz; Alsaedi, Ahmed

    2018-03-01

    Mixed convection stagnation point flow of nanofluid by a vertical permeable circular cylinder has been addressed. Water is treated as ordinary liquid while nanoparticles include aluminium oxide, copper and titanium dioxide. Homogeneous-heterogeneous reactions are considered. The nonlinear higher order expressions are changed into first ordinary differential equations and then solved by built-in-Shooting method in mathematica. The results of velocity, temperature, concentration, skin friction and local Nusselt number are discussed. Our results demonstrate that surface drag force and heat transfer rate are enhanced linearly for higher estimation of curvature parameter. Further surface drag force decays for aluminium oxide and it enhances for copper nanoparticle. Heat transfer rate enhances with increasing all three types of nanoparticles. In addition, the lowest heat transfer rate is obtained in case of titanium dioxide when compared with copper and aluminium oxide.

  12. External Load Affects Ground Reaction Force Parameters Non-uniformly during Running in Weightlessness

    Science.gov (United States)

    DeWitt, John; Schaffner, Grant; Laughlin, Mitzi; Loehr, James; Hagan, R. Donald

    2004-01-01

    Long-term exposure to microgravity induces detrimefits to the musculcskdetal system (Schneider et al., 1995; LeBlanc et al., 2000). Treadmill exercise is used onboard the International Space Station as an exercise countermeasure to musculoskeletal deconditioning due to spaceflight. During locomotive exercise in weightlessness (0G), crewmembers wear a harness attached to an external loading mechanism (EL). The EL pulls the crewmember toward the treadmill, and provides resistive load during the impact and propulsive phases of gait. The resulting forces may be important in stimulating bone maintenance (Turner, 1998). The EL can be applied via a bungee and carabineer clip configuration attached to the harness and can be manipulated to create varying amounts of load levels during exercise. Ground-based research performed using a vertically mounted treadmill found that peak ground reaction forces (GRF) during running at an EL of less than one body weight (BW) are less than those that occur during running in normal gravity (1G) (Davis et al., 1996). However, it is not known how the GRF are affected by the EL in a true OG environment. Locomotion while suspended may result in biomechanics that differ from free running. The purpose of this investigation was to determine how EL affects peak impact force, peak propulsive force, loading rate, and impulse of the GRF during running in 0G. It was hypothesized that increasing EL would result in increases in each GRF parameter.

  13. Radiation-reaction force on a small charged body to second order

    Science.gov (United States)

    Moxon, Jordan; Flanagan, Éanna

    2018-05-01

    In classical electrodynamics, an accelerating charged body emits radiation and experiences a corresponding radiation-reaction force, or self-force. We extend to higher order in the total charge a previous rigorous derivation of the electromagnetic self-force in flat spacetime by Gralla, Harte, and Wald. The method introduced by Gralla, Harte, and Wald computes the self-force from the Maxwell field equations and conservation of stress-energy in a limit where the charge, size, and mass of the body go to zero, and it does not require regularization of a singular self-field. For our higher-order computation, an adjustment of the definition of the mass of the body is necessary to avoid including self-energy from the electromagnetic field sourced by the body in the distant past. We derive the evolution equations for the mass, spin, and center-of-mass position of the body through second order. We derive, for the first time, the second-order acceleration dependence of the evolution of the spin (self-torque), as well as a mixing between the extended body effects and the acceleration-dependent effects on the overall body motion.

  14. FEATURES OF MEASURING IN LIQUID MEDIA BY ATOMIC FORCE MICROSCOPY

    Directory of Open Access Journals (Sweden)

    Mikhail V. Zhukov

    2016-11-01

    Full Text Available Subject of Research.The paper presents results of experimental study of measurement features in liquids by atomic force microscope to identify the best modes and buffered media as well as to find possible image artifacts and ways of their elimination. Method. The atomic force microscope Ntegra Aura (NT-MDT, Russia with standard prism probe holder and liquid cell was used to carry out measurements in liquids. The calibration lattice TGQ1 (NT-MDT, Russia was chosen as investigated structure with a fixed shape and height. Main Results. The research of probe functioning in specific pH liquids (distilled water, PBS - sodium phosphate buffer, Na2HPO4 - borate buffer, NaOH 0.1 M, NaOH 0.5 M was carried out in contact and semi-contact modes. The optimal operating conditions and the best media for the liquid measurements were found. Comparison of atomic force microscopy data with the results of lattice study by scanning electron microscopy was performed. The features of the feedback system response in the «probe-surface» interaction were considered by the approach/retraction curves in the different environments. An artifact of image inversion was analyzed and recommendation for its elimination was provided. Practical Relevance. These studies reveal the possibility of fine alignment of research method for objects of organic and inorganic nature by atomic force microscopy in liquid media.

  15. Optical tweezers force measurements to study parasites chemotaxis

    Science.gov (United States)

    de Thomaz, A. A.; Pozzo, L. Y.; Fontes, A.; Almeida, D. B.; Stahl, C. V.; Santos-Mallet, J. R.; Gomes, S. A. O.; Feder, D.; Ayres, D. C.; Giorgio, S.; Cesar, C. L.

    2009-07-01

    In this work, we propose a methodology to study microorganisms chemotaxis in real time using an Optical Tweezers system. Optical Tweezers allowed real time measurements of the force vectors, strength and direction, of living parasites under chemical or other kinds of gradients. This seems to be the ideal tool to perform observations of taxis response of cells and microorganisms with high sensitivity to capture instantaneous responses to a given stimulus. Forces involved in the movement of unicellular parasites are very small, in the femto-pico-Newton range, about the same order of magnitude of the forces generated in an Optical Tweezers. We applied this methodology to investigate the Leishmania amazonensis (L. amazonensis) and Trypanossoma cruzi (T. cruzi) under distinct situations.

  16. The formulation of a peer evaluation measure for special forces: operational forces operator traits and attitude questionnaire (SFO-TAQ)

    CSIR Research Space (South Africa)

    Van Heerden, A

    2016-11-01

    Full Text Available International Military Testing Association (IMTA) Conference, New Delhi, India, 7-11 November 2016 The formulation of a peer evaluation measure for special forces: operational forces operator traits and attitude questionnaire (SFO-TAQ) Van Heerden A...

  17. Estimation of vertical ground reaction forces and sagittal knee kinematics during running using three inertial sensors

    NARCIS (Netherlands)

    Wouda, Frank J.; Giuberti, Matteo; Bellusci, Giovanni; Maartens, Erik; Reenalda, Jasper; van Beijnum, Bernhard J.F.; Veltink, Peter H.

    2018-01-01

    Analysis of running mechanics has traditionally been limited to a gait laboratory using either force plates or an instrumented treadmill in combination with a full-body optical motion capture system. With the introduction of inertial motion capture systems, it becomes possible to measure kinematics

  18. Development of a shear force measurement dummy for seat comfort.

    Directory of Open Access Journals (Sweden)

    Seong Guk Kim

    Full Text Available Seat comfort is one of the main factors that consumers consider when purchasing a car. In this study, we develop a dummy with a shear-force sensor to evaluate seat comfort. The sensor has dimensions of 25 mm × 25 mm × 26 mm and is made of S45C. Electroless nickel plating is employed to coat its surface in order to prevent corrosion and oxidation. The proposed sensor is validated using a qualified load cell and shows high accuracy and precision (measurement range: -30-30 N; sensitivity: 0.1 N; linear relationship: R = 0.999; transverse sensitivity: <1%. The dummy is manufactured in compliance with the SAE standards (SAE J826 and incorporates shear sensors into its design. We measure the shear force under four driving conditions and at five different speeds using a sedan; results showed that the shear force increases with speed under all driving conditions. In the case of acceleration and deceleration, shear force significantly changes in the lower body of the dummy. During right and left turns, it significantly changes in the upper body of the dummy.

  19. Development of a shear force measurement dummy for seat comfort.

    Science.gov (United States)

    Kim, Seong Guk; Ko, Chang-Yong; Kim, Dong Hyun; Song, Ye Eun; Kang, Tae Uk; Ahn, Sungwoo; Lim, Dohyung; Kim, Han Sung

    2017-01-01

    Seat comfort is one of the main factors that consumers consider when purchasing a car. In this study, we develop a dummy with a shear-force sensor to evaluate seat comfort. The sensor has dimensions of 25 mm × 25 mm × 26 mm and is made of S45C. Electroless nickel plating is employed to coat its surface in order to prevent corrosion and oxidation. The proposed sensor is validated using a qualified load cell and shows high accuracy and precision (measurement range: -30-30 N; sensitivity: 0.1 N; linear relationship: R = 0.999; transverse sensitivity: <1%). The dummy is manufactured in compliance with the SAE standards (SAE J826) and incorporates shear sensors into its design. We measure the shear force under four driving conditions and at five different speeds using a sedan; results showed that the shear force increases with speed under all driving conditions. In the case of acceleration and deceleration, shear force significantly changes in the lower body of the dummy. During right and left turns, it significantly changes in the upper body of the dummy.

  20. Facility for the measurement of proton polarization in nuclear reactions

    Energy Technology Data Exchange (ETDEWEB)

    Slobodrian, R J; Irshad, M; Labrie, R; Rioux, C; Roy, R; Pigeon, R [Laval Univ., Quebec City (Canada). Lab. de Physique Nucleaire

    1979-02-15

    A polarimetry facility based on high resolution and high efficiency silicon polarimeters with on-line particle identification is described. It has proven its capability to measure polarization in (/sup 3/He, p(pol)) reaction with cross section levels of 40 ..mu..b/sr.

  1. Online Measurement of Oxygen-Dependent Enzyme Reaction Kinetics

    DEFF Research Database (Denmark)

    Meissner, Murray Peter; Nordblad, Mathias; Woodley, John M

    2018-01-01

    accurate measurement of the oxygen mass balance in the gas-phase of a reactor. The method was successfully validated and demonstrated using two model reactions: firstly the oxidation of glucose by glucose oxidase and secondly the Baeyer-Villiger oxidation of macrocyclic ketones to lactones. Initial...

  2. Standardized voluntary force measurement in a lower extremity rehabilitation robot

    Directory of Open Access Journals (Sweden)

    Bolliger Marc

    2008-10-01

    Full Text Available Abstract Background Isometric force measurements in the lower extremity are widely used in rehabilitation of subjects with neurological movement disorders (NMD because walking ability has been shown to be related to muscle strength. Therefore muscle strength measurements can be used to monitor and control the effects of training programs. A new method to assess isometric muscle force was implemented in the driven gait orthosis (DGO Lokomat. To evaluate the capabilities of this new measurement method, inter- and intra-rater reliability were assessed. Methods Reliability was assessed in subjects with and without NMD. Subjects were tested twice on the same day by two different therapists to test inter-rater reliability and on two separate days by the same therapist to test intra-rater reliability. Results Results showed fair to good reliability for the new measurement method to assess isometric muscle force of lower extremities. In subjects without NMD, intraclass correlation coefficients (ICC for inter-rater reliability ranged from 0.72 to 0.97 and intra-rater reliability from 0.71 to 0.90. In subjects with NMD, ICC ranged from 0.66 to 0.97 for inter-rater and from 0.50 to 0.96 for intra-rater reliability. Conclusion Inter- and intra- rater reliability of an assessment method for measuring maximal voluntary isometric muscle force of lower extremities was demonstrated. We suggest that this method is a valuable tool for documentation and controlling of the rehabilitation process in patients using a DGO.

  3. Multi-segment foot kinematics and ground reaction forces during gait of individuals with plantar fasciitis.

    Science.gov (United States)

    Chang, Ryan; Rodrigues, Pedro A; Van Emmerik, Richard E A; Hamill, Joseph

    2014-08-22

    Clinically, plantar fasciitis (PF) is believed to be a result and/or prolonged by overpronation and excessive loading, but there is little biomechanical data to support this assertion. The purpose of this study was to determine the differences between healthy individuals and those with PF in (1) rearfoot motion, (2) medial forefoot motion, (3) first metatarsal phalangeal joint (FMPJ) motion, and (4) ground reaction forces (GRF). We recruited healthy (n=22) and chronic PF individuals (n=22, symptomatic over three months) of similar age, height, weight, and foot shape (p>0.05). Retro-reflective skin markers were fixed according to a multi-segment foot and shank model. Ground reaction forces and three dimensional kinematics of the shank, rearfoot, medial forefoot, and hallux segment were captured as individuals walked at 1.35 ms(-1). Despite similarities in foot anthropometrics, when compared to healthy individuals, individuals with PF exhibited significantly (pfoot kinematics and kinetics. Consistent with the theoretical injury mechanisms of PF, we found these individuals to have greater total rearfoot eversion and peak FMPJ dorsiflexion, which may put undue loads on the plantar fascia. Meanwhile, increased medial forefoot plantar flexion at initial contact and decreased propulsive GRF are suggestive of compensatory responses, perhaps to manage pain. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. [Measurements of observables of pion-nucleon reactions]. Progress report

    International Nuclear Information System (INIS)

    Sadler, M.E.

    1985-01-01

    This document reports the progress of the research of pion reactions. These include (1) a study to measure observables in the pion-nucleon system in the momentum interval 400 to 700 MeV/c, (2) differential cross section measurements at low energy for pion-nucleon charge exchange, and (3) elastic and inelastic scattering of π +- on 3 H and 3 He. Individual experiments will be indexed separately

  5. Novel parallel plate condenser for single particle electrostatic force measurements in atomic force microscope

    KAUST Repository

    Kwek, Jin Wang

    2011-07-01

    A combination of small parallel plate condenser with Indium Tin Oxide (ITO) glass slides as electrodes and an atomic force microscope (AFM) is used to characterize the electrostatic behavior of single glass bead microparticles (105-150 μm) glued to the AFM cantilever. This novel setup allows measurements of the electrostatic forces acting on a particle in an applied electrical field to be performed in ambient air conditions. By varying the position of the microparticle between the electrodes and the strength of the applied electric field, the relative contributions of the particle net charge, induced and image charges were investigated. When the microparticle is positioned in the middle of the electrodes, the force acting on the microparticle was linear with the applied electric field and proportional to the microparticle net charge. At distances close to the bottom electrode, the force follows a parabolic relationship with the applied electric field reflecting the contributions of induced and image charges. The method can be used for the rapid evaluation of the charging and polarizability properties of the microparticle as well as an alternative to the conventional Faraday\\'s pail technique. © 2011 Elsevier B.V.

  6. Indirect Measurements for (p,α) Reactions Involving Boron Isotopes

    International Nuclear Information System (INIS)

    Lamia, L.; Spitaleri, C.; Romano, S.; Cherubini, S.; Crucilla, V.; Gulino, M.; La Cognata, M.; Pizzone, R. G.; Puglia, S. M. R.; Sergi, M. L.; Tudisco, S.; Tumino, A.; Carlin, N.; Szanto, M. G. del; Liguori Neto, R.; Moura, M. M. de; Munhoz, M. G.; Souza, F. A.; Suaide, A. A. P.; Szanto, E.

    2008-01-01

    Light elements lithium, beryllium and boron (LiBeB) were used in the last years as 'possible probe' for a deeper understanding of some extra-mixing phenomena occurring in young Main-Sequence stars. They are mainly destroyed by (p,α) reactions and cross section measurements for such channels are then needed. The Trojan Horse Method (THM) allows one to extract the astrophysical S(E)-factor without the experience of tunneling through the Coulomb barrier. In this work a resume of the recent results about the 11 B(p,α 0 ) 8 Be and 10 B(p,α) 7 Be reactions is shown

  7. Estimation of Tri-Axial Walking Ground Reaction Forces of Left and Right Foot from Total Forces in Real-Life Environments

    Directory of Open Access Journals (Sweden)

    Erfan Shahabpoor

    2018-06-01

    Full Text Available Continuous monitoring of natural human gait in real-life environments is essential in many applications including disease monitoring, rehabilitation, and professional sports. Wearable inertial measurement units are successfully used to measure body kinematics in real-life environments and to estimate total walking ground reaction forces GRF(t using equations of motion. However, for inverse dynamics and clinical gait analysis, the GRF(t of each foot is required separately. Using an experimental dataset of 1243 tri-axial separate-foot GRF(t time histories measured by the authors across eight years, this study proposes the ‘Twin Polynomial Method’ (TPM to estimate the tri-axial left and right foot GRF(t signals from the total GRF(t signals. For each gait cycle, TPM fits polynomials of degree five, eight, and nine to the known single-support part of the left and right foot vertical, anterior-posterior, and medial-lateral GRF(t signals, respectively, to extrapolate the unknown double-support parts of the corresponding GRF(t signals. Validation of the proposed method both with force plate measurements (gold standard in the laboratory, and in real-life environment showed a peak-to-peak normalized root mean square error of less than 2.5%, 6.5% and 7.5% for the estimated GRF(t signals in the vertical, anterior-posterior and medial-lateral directions, respectively. These values show considerable improvement compared with the currently available GRF(t decomposition methods in the literature.

  8. Ground reaction forces during level ground walking with body weight unloading

    Science.gov (United States)

    Barela, Ana M. F.; de Freitas, Paulo B.; Celestino, Melissa L.; Camargo, Marcela R.; Barela, José A.

    2014-01-01

    Background: Partial body weight support (BWS) systems have been broadly used with treadmills as a strategy for gait training of individuals with gait impairments. Considering that we usually walk on level ground and that BWS is achieved by altering the load on the plantar surface of the foot, it would be important to investigate some ground reaction force (GRF) parameters in healthy individuals walking on level ground with BWS to better implement rehabilitation protocols for individuals with gait impairments. Objective: To describe the effects of body weight unloading on GRF parameters as healthy young adults walked with BWS on level ground. Method: Eighteen healthy young adults (27±4 years old) walked on a walkway, with two force plates embedded in the middle of it, wearing a harness connected to a BWS system, with 0%, 15%, and 30% BWS. Vertical and horizontal peaks and vertical valley of GRF, weight acceptance and push-off rates, and impulse were calculated and compared across the three experimental conditions. Results: Overall, participants walked more slowly with the BWS system on level ground compared to their normal walking speed. As body weight unloading increased, the magnitude of the GRF forces decreased. Conversely, weight acceptance rate was similar among conditions. Conclusions: Different amounts of body weight unloading promote different outputs of GRF parameters, even with the same mean walk speed. The only parameter that was similar among the three experimental conditions was the weight acceptance rate. PMID:25590450

  9. Ground reaction forces during level ground walking with body weight unloading

    Directory of Open Access Journals (Sweden)

    Ana M. F. Barela

    2014-12-01

    Full Text Available Background: Partial body weight support (BWS systems have been broadly used with treadmills as a strategy for gait training of individuals with gait impairments. Considering that we usually walk on level ground and that BWS is achieved by altering the load on the plantar surface of the foot, it would be important to investigate some ground reaction force (GRF parameters in healthy individuals walking on level ground with BWS to better implement rehabilitation protocols for individuals with gait impairments. Objective: To describe the effects of body weight unloading on GRF parameters as healthy young adults walked with BWS on level ground. Method: Eighteen healthy young adults (27±4 years old walked on a walkway, with two force plates embedded in the middle of it, wearing a harness connected to a BWS system, with 0%, 15%, and 30% BWS. Vertical and horizontal peaks and vertical valley of GRF, weight acceptance and push-off rates, and impulse were calculated and compared across the three experimental conditions. Results: Overall, participants walked more slowly with the BWS system on level ground compared to their normal walking speed. As body weight unloading increased, the magnitude of the GRF forces decreased. Conversely, weight acceptance rate was similar among conditions. Conclusions: Different amounts of body weight unloading promote different outputs of GRF parameters, even with the same mean walk speed. The only parameter that was similar among the three experimental conditions was the weight acceptance rate.

  10. Factors that influence ground reaction force profiles during counter movement jumping.

    Science.gov (United States)

    Eagles, Alexander N; Sayers, Mark G; Lovell, Dale I

    2017-05-01

    The purpose of this study was to examine how hip, knee and ankle kinetics and kinematics influence effective impulse production during countermovement jumps. Eighteen semi-professional soccer players (22.8±2.2 years) volunteered to participate in the study. Participants completed three maximal countermovement jumps on two force platforms (1000 Hz) that were linked to a nine camera infrared motion capture system (500 Hz). Kinetic and kinematic data revealed jumpers who fail to achieve uniform ground reaction force curves that result in optimal impulse production during their jump always display hip adduction and or hip internal rotation during the concentric phase of the countermovement jump. The variation of hip adduction and or internal rotation likely represents failed joint transition during the concentric phase of the countermovement jump and appears to account for a non-uniform force trace seen in these jumpers. The findings suggest rehabilitation and conditioning exercises for injury prevention and performance may benefit from targeting frontal and transverse plane movement.

  11. Alterations to the orientation of the ground reaction force vector affect sprint acceleration performance in team sports athletes.

    Science.gov (United States)

    Bezodis, Neil E; North, Jamie S; Razavet, Jane L

    2017-09-01

    A more horizontally oriented ground reaction force vector is related to higher levels of sprint acceleration performance across a range of athletes. However, the effects of acute experimental alterations to the force vector orientation within athletes are unknown. Fifteen male team sports athletes completed maximal effort 10-m accelerations in three conditions following different verbal instructions intended to manipulate the force vector orientation. Ground reaction forces (GRFs) were collected from the step nearest 5-m and stance leg kinematics at touchdown were also analysed to understand specific kinematic features of touchdown technique which may influence the consequent force vector orientation. Magnitude-based inferences were used to compare findings between conditions. There was a likely more horizontally oriented ground reaction force vector and a likely lower peak vertical force in the control condition compared with the experimental conditions. 10-m sprint time was very likely quickest in the control condition which confirmed the importance of force vector orientation for acceleration performance on a within-athlete basis. The stance leg kinematics revealed that a more horizontally oriented force vector during stance was preceded at touchdown by a likely more dorsiflexed ankle, a likely more flexed knee, and a possibly or likely greater hip extension velocity.

  12. The role of military footwear and workload on ground reaction forces during a simulated lateral ankle sprain mechanism.

    Science.gov (United States)

    Simpson, Jeffrey D; DeBusk, Hunter; Hill, Christopher; Knight, Adam; Chander, Harish

    2018-03-01

    Ankle sprains are a common orthopedic injury in military populations, which may be attributed to occupational demands and footwear. Minimalist military boots have become popular, but their influence on ground reaction force (GRF) attenuation capabilities during an ankle inversion perturbation are unknown. Therefore, the purpose of this study was to examine potential differences in GRFs during an ankle inversion perturbation in a standard issue (STN) and minimalist military boot (MIN) before and after a simulated military workload. Twenty-one healthy adult males completed an ankle inversion perturbation protocol in each footwear condition before and after an incremental treadmill exercise protocol to volitional exhaustion while wearing a 16kg rucksack. The ankle inversion perturbation protocol consisted of stepping down from a 27cm box onto a force platform with a fulcrum (FUL), which created 25° of inversion upon landing, or flat (FLT) outer sole attached to the plantar aspect of the participants' footwear in random order. Peak vertical, anterior/posterior, and medial/lateral components of the GRF during FUL and FLT conditions were assessed, normalized to multiples of body weight in each footwear. Dependent variables were then analyzed using separate 2 (footwear)×2 (time) repeated measures ANOVA (pfootwear demonstrated significantly greater vertical GRF and significantly less medial GRF during the FUL condition. These results indicate that various mechanical and design characteristics of military footwear may influence GRF attenuation capabilities and ankle joint loading when the foot/ankle complex is forced into inversion. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Diameter measurements of polystyrene particles with atomic force microscopy

    International Nuclear Information System (INIS)

    Garnaes, J

    2011-01-01

    The size of (nano) particles is a key parameter used in controlling their function. The particle size is also important in order to understand their physical and chemical properties and regulate their number in health and safety issues. In this work, the geometric diameters of polystyrene spheres of nominal diameter 100 nm are measured using atomic force microscopy. The measurements are based on the apex height and on the average distance between neighbouring spheres when they form a close-packed monolayer on a flat mica substrate. The most important influence parameters for the determination of the geometric diameter are the lateral air gaps and deformation of the spheres. The lateral air gaps are caused by significant size variations of the individual spheres, and a correction is calculated based on the simulation of packing of spheres. The deformation of the spheres is caused mainly by capillary forces acting when they are in contact with each other or with the mica substrate. Based on calculated capillary forces and the literature values of the elastic properties of the polystyrene and mica, the deformation is estimated to be 2 nm with a standard uncertainty of 2 nm. The geometric diameter of the polystyrene spheres was measured with a combined standard uncertainty of ≈3 nm. The measured vertical diameter of 92.3 nm and the certified mobility equivalent diameter measured by differential mobility analysis (DMA) are marginally consistent at a confidence level of 95%. However, the measured lateral geometric diameter was 98.9 nm and is in good agreement with DMA

  14. Use of piezoelectric multicomponent force measuring devices in fluid mechanics

    Science.gov (United States)

    Richter, A.; Stefan, K.

    1979-01-01

    The characterisitics of piezoelectric multicomponent transducers are discussed, giving attention to the advantages of quartz over other materials. The main advantage of piezoelectric devices in aerodynamic studies is their ability to indicate rapid changes in the values of physical parameters. Problems in the accuracy of measurments by piezoelectric devices can be overcome by suitable design approaches. A practical example is given of how such can be utilized to measure rapid fluctuations of fluid forces exerted on a circular cylinder mounted in a water channel.

  15. Effect of lateralized design on muscle and joint reaction forces for reverse shoulder arthroplasty.

    Science.gov (United States)

    Liou, William; Yang, Yang; Petersen-Fitts, Graysen R; Lombardo, Daniel J; Stine, Sasha; Sabesan, Vani J

    2017-04-01

    Manufacturers of reverse shoulder arthroplasty (RSA) implants have recently designed innovative implants to optimize performance in rotator cuff-deficient shoulders. These advancements are not without tradeoffs and can have negative biomechanical effects. The objective of this study was to develop an integrated finite element analysis-kinematic model to compare the muscle forces and joint reaction forces (JRFs) of 3 different RSA designs. A kinematic model of a normal shoulder joint was adapted from the Delft model and integrated with the well-validated OpenSim shoulder model. Static optimizations then allowed for calculation of the individual muscle forces, moment arms, and JRFs relative to net joint moments. Three-dimensional computer models of 3 RSA designs-humeral lateralized design (HLD), glenoid lateralized design, and Grammont design-were integrated, and parametric studies were performed. Overall, there were decreases in deltoid and rotator cuff muscle forces for all 3 RSA designs. These decreases were greatest in the middle deltoid of the HLD model for abduction and flexion and in the rotator cuff muscles under both internal rotation and external rotation. The JRFs in abduction and flexion decreased similarly for all RSA designs compared with the normal shoulder model, with the greatest decrease seen in the HLD model. These findings demonstrate that the design characteristics implicit in these modified RSA prostheses result in mechanical differences most prominently seen in the deltoid muscle and overall JRFs. Further research using this novel integrated model can help guide continued optimization of RSA design and clinical outcomes. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  16. Ankle brace attenuates the medial-lateral ground reaction force during basketball rebound jump

    Directory of Open Access Journals (Sweden)

    Alex Castro

    Full Text Available ABSTRACT Introduction: The jump landing is the leading cause for ankle injuries in basketball. It has been shown that the use of ankle brace is effective to prevent these injuries by increasing the mechanical stability of the ankle at the initial contact of the foot with the ground. Objective: To investigate the effects of ankle brace on the ground reaction force (GRF during the simulation of a basketball rebound jump. Method: Eleven young male basketball players randomly carried out a simulated basketball rebound jump under two conditions, with and without ankle brace (lace-up. Dynamic parameters of vertical GRF (take-off and landing vertical peaks, time to take-off and landing vertical peaks, take-off impulse peak, impulse at 50 milliseconds of landing, and jump height and medial-lateral (take-off and landing medial-lateral peaks, and time to reach medial-lateral peaks at take-off and landing were recorded by force platform during rebound jumps in each tested condition. The comparisons between the tested conditions were performed by paired t test (P0.05. Conclusion: The use of ankle brace during basketball rebound jumps attenuates the magnitude of medial-lateral GRF on the landing phase, without changing the vertical GRF. This finding indicates that the use of brace increases the medial-lateral mechanical protection by decreasing the shear force exerted on the athlete’s body without change the application of propulsive forces in the take-off and the impact absorption quality in the landing during the basketball rebound jump.

  17. Comparison of Ground Reaction Forces, Center of Pressure and Body Center of Mass Changes in the Voluntary, Semi-Voluntary and Involuntary Gait Termination in Healthy Young Men

    Directory of Open Access Journals (Sweden)

    behrooz teymourian

    2016-03-01

    Full Text Available Objective: The aim of this study was comparing the ground reaction forces, center of pressure and body center of mass changes in voluntary, semi-voluntary and involuntary gait termination in healthy young men. Methods: In this study, 12 young men performed termination of gait in three different patterns. The variable of peak antero-posterior and vertical forces in two directions at both limbs, the time to reach peak and average forces in every limb in both directions, the center of pressure displacement of medio-lateral and antero-posterior direction for each limb and the net center of pressure and the displacement of the center of mass motion in all three motion plates were recorded using motion analysis system and force plate.The repeated measurements test was used to compare three patterns of gait termination at significance level of p&le0.5. Results: The results showed a significant difference in variables of peak antero-posterior force, the time to reach peak antero-posterior force and mean antero-posterior forces of the leading limb, the peak antero-posterior force of the trialing limbs, the depth force of leading limbs, medio-lateral cop of leading limbs displacement and vertical displacement of the center of mass, among different patterns of gait termination. Conclusion: While walking, the probability of a fall or collision damage, when a sudden or unexpected stop is required, increases. Therefore, more coordination between neuromuscular systems is required.

  18. How to Measure Load-Dependent Kinetics of Individual Motor Molecules Without a Force-Clamp

    DEFF Research Database (Denmark)

    Sung, Jongmin; Mortensen, Kim; Spudich, James A.

    Molecular motors are responsible for numerous cellular processes from cargo transport to heart contraction. Their interactions with other cellular components are often transient and exhibit kinetics that depend on load. Here, we measure such interactions using a new method, Harmonic Force...... and efficient. The protocol accumulates statistics fast enough to deliver single-molecule results from single-molecule experiments. We demonstrate the method's performance by measuring the force-dependent kinetics of individual human beta-cardiac myosin molecules interacting with an actin filament...... at physiological ATP concentration. We show that a molecule's ADP release rate depends exponentially on the applied load. This points to Kramer's Brownian diffusion model of chemical reactions as explanation why muscle contracts with a velocity inversely proportional to external load....

  19. 17F breakup reactions: a touchstone for indirect measurements

    International Nuclear Information System (INIS)

    De Napoli, M.; Raciti, G.; Sfienti, C.; Capel, P.; Baye, D.; Descouvemont, P.; Sparenberg, J.-M.; Giacoppo, F.; Rapisarda, E.; Cardella, G.; Mazzocchi, C.

    2011-01-01

    An exclusive study of 17 F breakup reactions has been performed at the FRIBs facility of the Laboratori Nazionali del Sud in Catania (Italy). The experiment has been performed with the aim of testing the accuracy of the Coulomb-breakup indirect technique used to infer radiative-capture cross sections at low energies. This technique has been used in the 7 Be(p,γ) 8 B case, but has never been tested. By measuring the breakup of 17 F into 16 O+p, and comparing the inferred cross section for 16 O(p,γ) 17 F to direct precise measurements, the influence of E2 transitions and higher-order effects, that are predicted to be significant in Coulomb-breakup reactions, can be evaluated. The first results and preliminary model comparison are reported.

  20. Measuring the greenhouse effect and radiative forcing through the atmosphere

    Science.gov (United States)

    Philipona, Rolf; Kräuchi, Andreas; Brocard, Emmanuel

    2013-04-01

    In spite of a large body of existing measurements of incoming shortwave solar radiation and outgoing longwave terrestrial radiation at the Earth's surface and at the top of the atmosphere, there are few observations documenting how radiation profiles change through the atmosphere - information that is necessary to fully quantify the greenhouse effect of the Earth's atmosphere. Using weather balloons and specific radiometer equipped radiosondes, we continuously measured shortwave and longwave radiation fluxes from the surface of the Earth up to altitudes of 35 kilometers in the upper stratosphere. Comparing radiation profiles from night measurements with different amounts of water vapor, we show evidence of large greenhouse forcing. We show, that under cloud free conditions, water vapor increases with Clausius-Clapeyron ( 7% / K), and longwave downward radiation at the surface increases by 8 Watts per square meter per Kelvin. The longwave net radiation however, shows a positive increase (downward) of 2.4 Watts per square meter and Kelvin at the surface, which decreases with height and shows a similar but negative increase (upward) at the tropopause. Hence, increased tropospheric water vapor increases longwave net radiation towards the ground and towards space, and produces a heating of 0.42 Kelvin per Watt per square meter at the surface. References: Philipona et al., 2012: Solar and thermal radiation profiles and radiative forcing measured through the atmosphere. Geophys. Res. Lett., 39, L13806, doi: 10.1029/2012GL052087.

  1. Force measurements of a magnetic micro actuator proposed for a microvalve array

    International Nuclear Information System (INIS)

    Chang, Pauline J; Chang, Frank W; Yuen, Michelle C; Horsley, David A; Otillar, Robert

    2014-01-01

    Low-cost, easily-fabricated and power-efficient microvalves are necessary for many microfluidic lab-on-a-chip applications. In this study, we present a simple, low-power, scalable, CMOS-compatible magnetic actuator for microvalve applications composed of a paramagnetic bead as the ball valve over a picoliter reaction well etched into a silicon substrate. The paramagnetic bead, composed of either pure FeSi or magnetite in a SiO 2  matrix, is actuated by the local magnetic field gradient generated by a microcoil in an aqueous environment, and the reaction well is situated at the microcoil center. A permanent magnet beneath the microvalve device provides an external magnetic biasing field that magnetizes the bead, enabling bidirectional actuation and reducing the current required to actuate the bead to a level below 10 mA. The vertical and radial magnetic forces exerted on the bead by the microcoil were measured for both pure FeSi and composite beads and agree well with the predictions of 2D axisymmetric finite element method models. Vertical forces were within a range of 13–80 nN, and radial forces were 11–60 nN depending on the bead type. The threshold current required to initiate bead actuation was measured as a function of bead diameter and is found to scale inversely with volume for small beads, as expected based on the magnetic force model. To provide an estimate of the stiction force acting between the bead and the passivation layer on the substrate, repeated actuation trials were used to study the bead throw distance for substrates coated with silicon dioxide, Parylene-C, and photoresist. The stiction observed was lowest for a photoresist-coated substrate, while silicon dioxide and Parylene-C coated substrates exhibited similar levels of stiction. (paper)

  2. Machine learning techniques for gait biometric recognition using the ground reaction force

    CERN Document Server

    Mason, James Eric; Woungang, Isaac

    2016-01-01

    This book focuses on how machine learning techniques can be used to analyze and make use of one particular category of behavioral biometrics known as the gait biometric. A comprehensive Ground Reaction Force (GRF)-based Gait Biometrics Recognition framework is proposed and validated by experiments. In addition, an in-depth analysis of existing recognition techniques that are best suited for performing footstep GRF-based person recognition is also proposed, as well as a comparison of feature extractors, normalizers, and classifiers configurations that were never directly compared with one another in any previous GRF recognition research. Finally, a detailed theoretical overview of many existing machine learning techniques is presented, leading to a proposal of two novel data processing techniques developed specifically for the purpose of gait biometric recognition using GRF. This book · introduces novel machine-learning-based temporal normalization techniques · bridges research gaps concerning the effect of ...

  3. Using ground reaction force to predict knee kinetic asymmetry following anterior cruciate ligament reconstruction.

    Science.gov (United States)

    Dai, B; Butler, R J; Garrett, W E; Queen, R M

    2014-12-01

    Asymmetries in sagittal plane knee kinetics have been identified as a risk factor for anterior cruciate ligament (ACL) re-injury. Clinical tools are needed to identify the asymmetries. This study examined the relationships between knee kinetic asymmetries and ground reaction force (GRF) asymmetries during athletic tasks in adolescent patients following ACL reconstruction (ACL-R). Kinematic and GRF data were collected during a stop-jump task and a side-cutting task for 23 patients. Asymmetry indices between the surgical and non-surgical limbs were calculated for GRF and knee kinetic variables. For the stop-jump task, knee kinetics asymmetry indices were correlated with all GRF asymmetry indices (P kinetic asymmetry indices were correlated with the peak propulsion vertical GRF and vertical GRF impulse asymmetry indices (P kinetic asymmetries and therefore may assist in optimizing rehabilitation outcomes and minimizing re-injury rates. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Ground reaction forces and frictional demands during stair descent: effects of age and illumination.

    Science.gov (United States)

    Christina, Kathryn A; Cavanagh, Peter R

    2002-04-01

    Stair descent is an inherently risky and demanding task that older adults often encounter in everyday life. It is believed that slip between the foot or shoe sole and the stair surface may play a role in stair related falls, however, there are no reports on slip resistance requirements for stair descent. The aim of this study was to determine the required coefficient of friction (RCOF) necessary for safe stair descent in 12 young and 12 older adults, under varied illuminance conditions. The RCOF during stair descent was found to be comparable in magnitude and time to that for overground walking, and thus, with adequate footwear and dry stair surfaces, friction does not appear to be a major determinant of stair safety. Illuminance level had little effect on the dependent variables quantified in this study. However, the older participants demonstrated safer strategies than the young during stair descent, as reflected by differences in the ground reaction forces and lower RCOF.

  5. The influence of heel height on vertical ground reaction force during landing tasks in recreationally active and athletic collegiate females.

    Science.gov (United States)

    Lindenberg, Kelly M; Carcia, Christopher R

    2013-02-01

    To determine if heel height alters vertical ground reaction forces (vGRF) when landing from a forward hop or drop landing. Increased vGRF during landing are theorized to increase ACL injury risk in female athletes. Fifty collegiate females performed two single-limb landing tasks while wearing heel lifts of three different sizes (0, 12 & 24 mm) attached to the bottom of a athletic shoe. Using a force plate, peak vGRF at landing was examined. Repeated measures ANOVAs were used to determine the influence of heel height on the dependent measures. Forward hop task- Peak vGRF (normalized for body mass) with 0 mm, 12 mm, and 24 mm lifts were 2.613±0.498, 2.616±0.497 and 2.495±0.518% BW, respectively. Significant differences were noted between 0 and 24 mm lift (psneaker significantly alters peak vGRF upon landing from a unilateral forward hop but not from a jumping maneuver.

  6. Validity of a Simple Method for Measuring Force-Velocity-Power Profile in Countermovement Jump.

    Science.gov (United States)

    Jiménez-Reyes, Pedro; Samozino, Pierre; Pareja-Blanco, Fernando; Conceição, Filipe; Cuadrado-Peñafiel, Víctor; González-Badillo, Juan José; Morin, Jean-Benoît

    2017-01-01

    To analyze the reliability and validity of a simple computation method to evaluate force (F), velocity (v), and power (P) output during a countermovement jump (CMJ) suitable for use in field conditions and to verify the validity of this computation method to compute the CMJ force-velocity (F-v) profile (including unloaded and loaded jumps) in trained athletes. Sixteen high-level male sprinters and jumpers performed maximal CMJs under 6 different load conditions (0-87 kg). A force plate sampling at 1000 Hz was used to record vertical ground-reaction force and derive vertical-displacement data during CMJ trials. For each condition, mean F, v, and P of the push-off phase were determined from both force-plate data (reference method) and simple computation measures based on body mass, jump height (from flight time), and push-off distance and used to establish the linear F-v relationship for each individual. Mean absolute bias values were 0.9% (± 1.6%), 4.7% (± 6.2%), 3.7% (± 4.8%), and 5% (± 6.8%) for F, v, P, and slope of the F-v relationship (S Fv ), respectively. Both methods showed high correlations for F-v-profile-related variables (r = .985-.991). Finally, all variables computed from the simple method showed high reliability, with ICC >.980 and CV push-off distance, and jump height are known.

  7. The measurement of emotional reactions of bank clients

    Directory of Open Access Journals (Sweden)

    Marinković Veljko

    2014-01-01

    Full Text Available Focus on customers is an important factor in gaining sustainable competitive advantage of retail banks. Modern marketing-oriented banks have to be focused towards understanding and meeting the financial requirements of their clients. Attention of bank management should also be directed towards the study of quality of relationships between a bank and its clients. In this context, it is important to measure emotional reactions of clients. The aim of this paper is to identify the key drivers of emotional reactions. Specifically, two emotional reactions are observed in the paper: satisfaction and affective commitment. In the conducted study, two research models that include four independent variables (service quality, bank image, trust and social bonds are designed, wherein satisfaction is regarded as dependent variable in the first model, while affective commitment is given the role of dependent variable in the second model. The results indicate a moderate degree of satisfaction, but also a low level of affective commitment of the respondents. In addition, trust is stressed as the most important factor of emotional reactions. On the other hand, clients believe that banks provide a good quality service, where the quality stands out as an important driver of satisfaction, but not as a driver of affective commitment.

  8. Ground Reaction Force and Cadence during Stationary Running Sprint in Water and on Land.

    Science.gov (United States)

    Fontana, H de Brito; Ruschel, C; Haupenthal, A; Hubert, M; Roesler, H

    2015-06-01

    This study was aimed at analyzing the cadence (Cadmax) and the peak vertical ground reaction force (Fymax) during stationary running sprint on dry land and at hip and chest level of water immersion. We hypothesized that both Fymax and Cadmax depend on the level of immersion and that differences in Cadmax between immersions do not affect Fymax during stationary sprint. 32 subjects performed the exercise at maximum cadence at each immersion level and data were collected with force plates. The results show that Cadmax and Fymax decrease 17 and 58% from dry land to chest immersion respectively, with no effect of cadence on Fymax. While previous studies have shown similar neuromuscular responses between aquatic and on land stationary sprint, our results emphasize the differences in Fymax between environments and levels of immersion. Additionally, the characteristics of this exercise permit maximum movement speed in water to be close to the maximum speed on dry land. The valuable combination of reduced risk of orthopedic trauma with similar neuromuscular responses is provided by the stationary sprint exercise in water. The results of this study support the rationale behind the prescription of stationary sprinting in sports training sessions as well as rehabilitation programs. © Georg Thieme Verlag KG Stuttgart · New York.

  9. Functional data analysis on ground reaction force of military load carriage increment

    Science.gov (United States)

    Din, Wan Rozita Wan; Rambely, Azmin Sham

    2014-06-01

    Analysis of ground reaction force on military load carriage is done through functional data analysis (FDA) statistical technique. The main objective of the research is to investigate the effect of 10% load increment and to find the maximum suitable load for the Malaysian military. Ten military soldiers age 31 ± 6.2 years, weigh 71.6 ± 10.4 kg and height of 166.3 ± 5.9 cm carrying different military load range from 0% body weight (BW) up to 40% BW participated in an experiment to gather the GRF and kinematic data using Vicon Motion Analysis System, Kirstler force plates and thirty nine body markers. The analysis is conducted in sagittal, medial lateral and anterior posterior planes. The results show that 10% BW load increment has an effect when heel strike and toe-off for all the three planes analyzed with P-value less than 0.001 at 0.05 significant levels. FDA proves to be one of the best statistical techniques in analyzing the functional data. It has the ability to handle filtering, smoothing and curve aligning according to curve features and points of interest.

  10. Effects of velocity and weight support on ground reaction forces and metabolic power during running.

    Science.gov (United States)

    Grabowski, Alena M; Kram, Rodger

    2008-08-01

    The biomechanical and metabolic demands of human running are distinctly affected by velocity and body weight. As runners increase velocity, ground reaction forces (GRF) increase, which may increase the risk of an overuse injury, and more metabolic power is required to produce greater rates of muscular force generation. Running with weight support attenuates GRFs, but demands less metabolic power than normal weight running. We used a recently developed device (G-trainer) that uses positive air pressure around the lower body to support body weight during treadmill running. Our scientific goal was to quantify the separate and combined effects of running velocity and weight support on GRFs and metabolic power. After obtaining this basic data set, we identified velocity and weight support combinations that resulted in different peak GRFs, yet demanded the same metabolic power. Ideal combinations of velocity and weight could potentially reduce biomechanical risks by attenuating peak GRFs while maintaining aerobic and neuromuscular benefits. Indeed, we found many combinations that decreased peak vertical GRFs yet demanded the same metabolic power as running slower at normal weight. This approach of manipulating velocity and weight during running may prove effective as a training and/or rehabilitation strategy.

  11. The effects of baseball bat mass properties on swing mechanics, ground reaction forces, and swing timing.

    Science.gov (United States)

    Laughlin, Walter A; Fleisig, Glenn S; Aune, Kyle T; Diffendaffer, Alek Z

    2016-01-01

    Swing trajectory and ground reaction forces (GRF) of 30 collegiate baseball batters hitting a pitched ball were compared between a standard bat, a bat with extra weight about its barrel, and a bat with extra weight in its handle. It was hypothesised that when compared to a standard bat, only a handle-weighted bat would produce equivalent bat kinematics. It was also hypothesised that hitters would not produce equivalent GRFs for each weighted bat, but would maintain equivalent timing when compared to a standard bat. Data were collected utilising a 500 Hz motion capture system and 1,000 Hz force plate system. Data between bats were considered equivalent when the 95% confidence interval of the difference was contained entirely within ±5% of the standard bat mean value. The handle-weighted bat had equivalent kinematics, whereas the barrel-weighted bat did not. Both weighted bats had equivalent peak GRF variables. Neither weighted bat maintained equivalence in the timing of bat kinematics and some peak GRFs. The ability to maintain swing kinematics with a handle-weighted bat may have implications for swing training and warm-up. However, altered timings of kinematics and kinetics require further research to understand the implications on returning to a conventionally weighted bat.

  12. Interactions between Rotavirus and Suwannee River Organic Matter: Aggregation, Deposition, and Adhesion Force Measurement

    KAUST Repository

    Gutierrez, Leonardo; Nguyen, Thanh H.

    2012-01-01

    M, rotavirus suspension remained stable for over 4 h. Atomic force microscopy (AFM) measurement for interaction force decay length at different ionic strengths showed that nonelectrostatic repulsive forces were mainly responsible for eliminating aggregation

  13. Measuring microscopic forces and torques using optical tweezers

    CSIR Research Space (South Africa)

    Mc

    2009-07-01

    Full Text Available stream_source_info McLaren_2009.pdf.txt stream_content_type text/plain stream_size 2976 Content-Encoding UTF-8 stream_name McLaren_2009.pdf.txt Content-Type text/plain; charset=UTF-8 Measuring microscopic forces... and torques using optical tweezers M.G. McLaren1,2, A. Forbes2,3,4 and E. Sideras-Haddad2 1 CSIR National Laser Centre 2 School of Physics, University of Witwatersrand 3 School of Physics, University of KwaZulu-Natal 4 School of Physics, University...

  14. Task modulation of the effects of brightness on reaction time and response force.

    Science.gov (United States)

    Jaśkowski, Piotr; Włodarczyk, Dariusz

    2006-08-01

    Van der Molen and Keuss [van der Molen, M.W., Keuss, P.J.G., 1979. The relationship between reaction time and intensity in discrete auditory tasks. Quarterly Journal of Experimental Psychology 31, 95-102; van der Molen, M.W., Keuss, P.J.G., 1981. Response selection and the processing of auditory intensity. Quarterly Journal of Experimental Psychology 33, 177-184] showed that paradoxically long reaction times (RT) occur with extremely loud auditory stimuli when the task is difficult (e.g. needs a response choice). It was argued that this paradoxical behavior of RT is due to active suppression of response prompting to prevent false responses. In the present experiments, we demonstrated that such an effect can also occur for visual stimuli provided that they are large enough. Additionally, we showed that response force exerted by participants on response keys monotonically grew with intensity for large stimuli but was independent of intensity for small visual stimuli. Bearing in mind that only large stimuli are believed to be arousing this pattern of results supports the arousal interpretation of the negative effect of loud stimuli on RT given by van der Molen and Keuss.

  15. Secondary standard neutron detector for measuring total reaction cross sections

    International Nuclear Information System (INIS)

    Sekharan, K.K.; Laumer, H.; Gabbard, F.

    1975-01-01

    A neutron detector has been constructed and calibrated for the accurate measurement of total neutron-production cross sections. The detector consists of a polyethylene sphere of 24'' diameter in which 8- 10 BF 3 counters have been installed radially. The relative efficiency of this detector has been determined for average neutron energies, from 30 keV to 1.5 MeV by counting neutrons from 7 Li(p,n) 7 Be. By adjusting the radial positions of the BF 3 counters in the polyethylene sphere the efficiency for neutron detection was made nearly constant for this energy range. Measurement of absolute efficiency for the same neutron energy range has been done by counting the neutrons from 51 V(p,n) 51 Cr and 57 Fe(p,n) 57 Co reactions and determining the absolute number of residual nuclei produced during the measurement of neutron yield. Details of absolute efficiency measurements and the use of the detector for measurement of total neutron yields from neutron producing reactions such as 23 Na(p,n) 23 Mg are given

  16. Uncertainty quantification in nanomechanical measurements using the atomic force microscope

    International Nuclear Information System (INIS)

    Wagner, Ryan; Raman, Arvind; Moon, Robert; Pratt, Jon; Shaw, Gordon

    2011-01-01

    Quantifying uncertainty in measured properties of nanomaterials is a prerequisite for the manufacture of reliable nanoengineered materials and products. Yet, rigorous uncertainty quantification (UQ) is rarely applied for material property measurements with the atomic force microscope (AFM), a widely used instrument that can measure properties at nanometer scale resolution of both inorganic and biological surfaces and nanomaterials. We present a framework to ascribe uncertainty to local nanomechanical properties of any nanoparticle or surface measured with the AFM by taking into account the main uncertainty sources inherent in such measurements. We demonstrate the framework by quantifying uncertainty in AFM-based measurements of the transverse elastic modulus of cellulose nanocrystals (CNCs), an abundant, plant-derived nanomaterial whose mechanical properties are comparable to Kevlar fibers. For a single, isolated CNC the transverse elastic modulus was found to have a mean of 8.1 GPa and a 95% confidence interval of 2.7–20 GPa. A key result is that multiple replicates of force–distance curves do not sample the important sources of uncertainty, which are systematic in nature. The dominant source of uncertainty is the nondimensional photodiode sensitivity calibration rather than the cantilever stiffness or Z-piezo calibrations. The results underscore the great need for, and open a path towards, quantifying and minimizing uncertainty in AFM-based material property measurements of nanoparticles, nanostructured surfaces, thin films, polymers and biomaterials.

  17. Force Measurement with a Piezoelectric Cantilever in a Scanning Force Microscope

    OpenAIRE

    Tansock, J.; Williams, C. C.

    1992-01-01

    Detection of surface forces between a tip and sample has been demonstrated with a piezoelectric cantilever in a scanning force microscope (SFM). The use of piezoelectric force sensing is particularly advantageous in semiconductor applications where stray light from conventional optical force-sensing methods can significantly modify the local carrier density. Additionally, the piezoelectric sensors are simple, provide good sensitivity to force, and can be batch fabricated. Our piezoelectric fo...

  18. Limitations of the Weissler reaction as a model reaction for measuring the efficiency of hydrodynamic cavitation.

    Science.gov (United States)

    Morison, K R; Hutchinson, C A

    2009-01-01

    The Weissler reaction in which iodide is oxidised to a tri-iodide complex (I(3)(-)) has been widely used for measurement of the intensity of ultrasonic and hydrodynamic cavitation. It was used in this work to compare ultrasonic cavitation at 24 kHz with hydrodynamic cavitation using two different devices, one a venturi and the other a sudden expansion, operated up to 8.7 bar. Hydrodynamic cavitation had a maximum efficiency of about 5 x 10(-11) moles of I(3)(-) per joule of energy compared with the maximum of almost 8 x 10(-11) mol J(-1) for ultrasonic cavitation. Hydrodynamic cavitation was found to be most effective at 10 degrees C compared with 20 degrees C and 30 degrees C and at higher upstream pressures. However, it was found that in hydrodynamic conditions, even without cavitation, I(3)(-) was consumed at a rapid rate leading to an equilibrium concentration. It was concluded that the Weissler reaction was not a good model reaction for the assessment of the effectiveness of hydrodynamic cavitation.

  19. Ground reaction force comparison of bilateral symmetry with pneumatic resistance squat device and free weights - biomed 2009.

    Science.gov (United States)

    Paulus, David C; Schilling, Brian K

    2009-01-01

    The unloading of spaceflight leads to bone and muscle atrophy, and a pneumatic resistance squat exercise countermeasure has the potential to provide optimized controllable resistance in a lightweight and compact configuration. However each end of the barbell in the proposed device is connected to a separate resistance cylinder which could lead to bilaterally asymmetric loading. Therefore, the purpose of the study is to compare the unilateral ground reaction forces (GRF) of the new squat device compared to free weights. Four previously trained men (mean +/- SD; age = 20+/-2 years, body mass = 99+/-18 kg) performed three sets of three repetitions of maximal exertion squat exercises with pneumatically controlled constant resistance and free weights each with a resistance level set to half of the body weight of each subject. Unilateral GRF data for each lifting modality at the negative to positive transition of the squat exercise was measured with a force plate under each foot. The pneumatic resistance GRF (N; mean +/- SD) was 749+/-114 on the left leg and 786+/-123 on the right leg and the free weight GRF was 786+/-114 left and 861+/-111 right resulting in a 5% difference between left and right GRF with pneumatics and 9% difference with free weights. The correlation coefficient between left and right GRF was 0.92 with pneumatics and 0.80 with free weights. Because the pneumatic device elicited more bilaterally symmetric GRF than traditional free weights, the separate resistance cylinders are an acceptable design configuration.

  20. Vertical ground reaction force in stationary running in water and on land: A study with a wide range of cadences.

    Science.gov (United States)

    de Brito Fontana, Heiliane; Ruschel, Caroline; Dell'Antonio, Elisa; Haupenthal, Alessandro; Pereira, Gustavo Soares; Roesler, Helio

    2018-04-01

    The aim of this study was to analyze the effect of cadence, immersion level as well as body density on the vertical component (Fy max ) of ground reaction force (GRF) during stationary running (SR). In a controlled, laboratory study, thirty-two subjects ran at a wide range of cadences (85-210 steps/min) in water, immersed to the hip and to the chest, and on dry land. Fy max. was verified by a waterproof force measurement system and predicted based on a statistical model including cadence, immersion ratio and body density. The effect of cadence was shown to depend on the environment: while Fy max increases linearly with increasing cadence on land; in water, Fy max reaches a plateau at both hip and chest immersions. All factors analyzed, cadence, immersion level and body density affected Fy max significantly, with immersion (aquatic × land environment) showing the greatest effect. In water, different cadences may lead to bigger changes in Fy max than the changes obtained by moving subjects from hip to chest immersion. A regression model able to predict 69% of Fy max variability in water was proposed and validated. Cadence, Immersion and body density affect Fy max in a significant and non-independent way. Besides a model of potential use in the prescription of stationary running in water, our analysis provides insights into the different responses of GRF to changes in exercise parameters between land and aquatic environment. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Ground reaction forces and knee mechanics in the weight acceptance phase of a dance leap take-off and landing.

    Science.gov (United States)

    Kulig, Kornelia; Fietzer, Abbigail L; Popovich, John M

    2011-01-01

    Aesthetic constraints allow dancers fewer technique modifications than other athletes to negotiate the demands of leaping. We examined vertical ground reaction force and knee mechanics during a saut de chat performed by healthy dancers. It was hypothesized that vertical ground reaction force during landing would exceed that of take-off, resulting in greater knee extensor moments and greater knee angular stiffness. Twelve dancers (six males, six females; age 18.9 ± 1.2 years, mass 59.2 ± 9.5 kg, height 1.68 ± 0.08 m, dance training 8.9 ± 5.1 years) with no history of low back pain or lower extremity pathology participated in the study. Saut de chat data were captured using an eight-camera Vicon system and AMTI force platforms. Peak ground reaction force was 26% greater during the landing phase, but did not result in increased peak knee extensor moments. Taking into account the 67% greater knee angular displacement during landing, this resulted in less knee angular stiffness during landing. In conclusion, landing was accomplished with less knee angular stiffness despite the greater peak ground reaction force. A link between decreased joint angular stiffness and increased soft tissue injury risk has been proposed elsewhere; therefore, landing from a saut de chat may be more injurious to the knee soft tissue than take-off.

  2. Measurement of Reactions on 30P for Nova Nucleosynthesis

    Science.gov (United States)

    Ma, Z.; Guidry, M. W.; Hix, W. R.; Smith, M. S.

    2003-05-01

    Replace these paragraphs with your abstract. We encourage you to include a sentence acknowledging your funding agency. In a recent study the 30P(p,gamma)31S rate played a crucial role in the synthesis of heavier nuclear species, from Si to Ca, in nova outbursts on ONe White Dwarfs [1]. The adopted rate of this reaction, based on a Hauser-Feshbach calculation [2], has a large uncertainty and could be as much as a factor of 100 too high or too low [3]. In their study, Jose et al.[1] varied the 30P(p,gamma)31S reaction rate within this uncertainty and found that, when rate is reduced by a factor of 100, the synthesis of elements above Si is lowered by a factor 10 with respect to the values found with the nominal rate. This has important consequences for nova nucleosynthesis, as overproduction of isotopes in the Si to Ca mass region has been observed in the ejecta from some nova explosions (e.g.,[4,5]). While generally valid at higher temperatures, Hauser-Feshbach calculations of the rates at nova temperatures can have large uncertainties. At these temperatures, the rate is more likely dominated by a few individual nuclear resonances. At present there are about 10 31S resonances known above the 30P + p threshold that may contribute to the 30P(p,gamma)31S reaction rate at nova temperatures. The excitation energies of these levels are known but spins and parities (for all but two) are not. We plan to measure the 30P(p,p)30P and 30P(p,gamma)31S reactions at HRIBF to better determine this reaction rate. A detailed description of the experiments will be given. We are also conducting a new nova nucleosynthesis simulation over multiple spatial zones of the exploding envelope to investigate the influence of the 30P(p,gamma)31S reaction rate on nova nucleosynthesis. The results of these calculations will be discussed. 1. Jose , J., Coc, A., Hernanz, M., Astrophys. J., 560, 897(2001). 2. Thielemann, F.-K et al., 1987, Advances in Nuclear Astrophysics, ed. E. Vangioni-Flam ( Gif

  3. Effect of Five-Finger Shoes on Vertical Ground Reaction Force Loading Rates and Perceived Comfort during the Stance Phase of the Running

    Directory of Open Access Journals (Sweden)

    Seyede Zeynab Hoseini

    2016-06-01

    Full Text Available Objective:  Increased vertical ground reaction force loading rates and lack of comfort footwear in the early stance phase can increase the risk of overuse injuries. The purpose of this study was to investigate the effect of Five-finger shoes on vertical ground reaction force loading rate and perceived comfort during the stance phase of running. Methods: 15 male students (aged 24 ± 5/24 years, weight 75/8 ± 4/61 kg, height 178/6 ± 6/64 cm were selected. Subjects were asked to run over a force plate, in control shoe, five finger shoe and barefoot conditions. Loading rate using the slope of the vertical reaction force and perceived comfort were determined using a visual analogue scale. One factor repeated measures ANOVA was used to test the loading rate hypothesis and Paired t-tests was used to test the meaningfulness of perceived comfort (P<0/05. Results: The effect of shoes on loading rate was found to be not significant (P=0.1. However, comfort of control shoes increased by 10. 92% as compared to that of five-finger shoes (P=0.001.  Conclusion: The loading rate of five-finger shoes is the same as that of barefoot during running; however, as subjects did not perceive them as comfortable as regular shoes are five-finger shoes cannot be advised as a desirable choice in exercises.

  4. Multilayer Steel Materials Deformation Resistance and Roll Force Measurement

    Directory of Open Access Journals (Sweden)

    A. G. Kolesnikov

    2014-01-01

    Full Text Available To create new types of cars, raise their reliability, gain operational life, and decrease in metal consumption of products it is necessary to improve mechanical, physical, and also special properties of the constructional materials applied in mechanical engineering. Presently, there are intensive researches and developments under way to create materials with ultrafine-grained structure (the sizes of grains in their crystal lattice make less than 1 micron in one of the measurements.BMSTU developed a manufacturing technology of multilayer steel sheets with steady ultrafine-grained structure based on the multiple hot rolling of billet as a composition consisting of the alternating metal sheets. A principled condition for implementation of such technology is existence of different crystallographic modifications in the adjoining sheets of the composition at specified temperature of rolling.Power parameters of rolling are important technical characteristics of the process. Usually, to determine a deformation resistance value when rolling the diverse multilayer materials, is used the actual resistance value averaging in relation to the components of the composition. The aim of this work is a comparative analysis of known calculated dependences with experimental data when rolling the 100-layer samples. Objects of research were the 100-layer compositions based on the alternating layers of steel 08H18N10 and U8.Experimental samples represented the vacuumized capsules with height, width, and length of 53 mm x 53 mm x 200 mm, respectively, in which there were the 100-layer packs from sheets, each of 0.5 mm, based on the composition of steels (U8+08H18N10. Rolling was made on the double-high mill with rolls of 160 mm in diameter during 19 passes to the thickness of 7 mm with the speed of 0,1 m/s. Relative sinking in each pass was accepted to be equal 10±2,5%. Rolling forces were measured by the strain-gauging method using the measuring cells, located under

  5. Squat Ground Reaction Force on a Horizontal Squat Device, Free Weights, and Smith Machine

    Science.gov (United States)

    Scott-Pandorf, Melissa M.; Newby, Nathaniel J.; Caldwell, Erin; DeWitt, John K.; Peters, Brian T.

    2010-01-01

    Bed rest is an analog to spaceflight and advancement of exercise countermeasures is dependent on the development of exercise equipment that closely mimic actual upright exercise. The Horizontal Squat Device (HSD) was developed to allow a supine exerciser to perform squats that mimic upright squat exercise. PURPOSE: To compare vertical ground reaction force (GRFv) on the HSD with Free Weight (FW) or Smith Machine (SM) during squat exercise. METHODS: Subjects (3F, 3M) performed sets of squat exercise with increasing loads up to 1-repetition (rep) maximum. GRF data were collected and compared with previous GRF data for squat exercise performed with FW & SM. Loads on the HSD were adjusted to magnitudes comparable with FW & SM by subtracting the subject s body weight (BW). Peak GRFv for 45-, 55-, 64-, & 73-kg loads above BW were calculated. Percent (%) difference between HSD and the two upright conditions were computed. Effect size was calculated for the 45-kg load. RESULTS: Most subjects were unable to lift >45 kg on the HSD; however, 1 subject completed all loads. Anecdotal evidence suggested that most subjects shoulders or back failed before their legs. The mean % difference are shown. In the 45-kg condition, effect sizes were 0.37 & 0.83 (p>0.05) for HSD vs. FW and HSD vs. SM, respectively, indicating no differences between exercise modes. CONCLUSION: When BW was added to the target load, results indicated that vertical forces were similar to those in FW and SM exercise. The exercise prescription for the HSD should include a total external resistance equivalent to goal load plus subject BW. The HSD may be used as an analog to upright exercise in bed rest studies, but because most subjects were unable to lift >45 kg, it may be necessary to prescribe higher reps and lower loads to better target the leg musculature

  6. Prototype to measure bracket debonding force in vivo

    Directory of Open Access Journals (Sweden)

    Jéssika Lagni Tonus

    Full Text Available ABSTRACT Introduction: Material biodegradation that occurs in the mouth may interfere in the bonding strength between the bracket and the enamel, causing lower bond strength values in vivo, in comparison with in vitro studies. Objective: To develop a prototype to measure bracket debonding force in vivo and to evaluate, in vitro, the bond strength obtained with the prototype. Methods: A original plier (3M Unitek was modified by adding one strain gauge directly connected to its claw. An electronic circuit performed the reading of the strain gauge, and the software installed in a computer recorded the values of the bracket debonding force, in kgf. Orthodontic brackets were bonded to the facial surface of 30 bovine incisors with adhesive materials. In Group 1 (n = 15, debonding was carried out with the prototype, while tensile bond strength testing was performed in Group 2 (n = 15. A universal testing machine was used for the second group. The adhesive remnant index (ARI was recorded. Results: According to Student’s t test (α = 0.05, Group 1 (2.96 MPa and Group 2 (3.08 MPa were not significantly different. ARI score of 3 was predominant in the two groups. Conclusion: The prototype proved to be reliable for obtaining in vivo bond strength values for orthodontic brackets.

  7. Prototype to measure bracket debonding force in vivo

    Science.gov (United States)

    Tonus, Jéssika Lagni; Manfroi, Fernanda Borguetti; Borges, Gilberto Antonio; Grigolo, Eduardo Correa; Helegda, Sérgio; Spohr, Ana Maria

    2017-01-01

    ABSTRACT Introduction: Material biodegradation that occurs in the mouth may interfere in the bonding strength between the bracket and the enamel, causing lower bond strength values in vivo, in comparison with in vitro studies. Objective: To develop a prototype to measure bracket debonding force in vivo and to evaluate, in vitro, the bond strength obtained with the prototype. Methods: A original plier (3M Unitek) was modified by adding one strain gauge directly connected to its claw. An electronic circuit performed the reading of the strain gauge, and the software installed in a computer recorded the values of the bracket debonding force, in kgf. Orthodontic brackets were bonded to the facial surface of 30 bovine incisors with adhesive materials. In Group 1 (n = 15), debonding was carried out with the prototype, while tensile bond strength testing was performed in Group 2 (n = 15). A universal testing machine was used for the second group. The adhesive remnant index (ARI) was recorded. Results: According to Student’s t test (α = 0.05), Group 1 (2.96 MPa) and Group 2 (3.08 MPa) were not significantly different. ARI score of 3 was predominant in the two groups. Conclusion: The prototype proved to be reliable for obtaining in vivo bond strength values for orthodontic brackets. PMID:28444011

  8. Effects of slip-induced changes in ankle movement on muscle activity and ground reaction forces during running acceleration

    DEFF Research Database (Denmark)

    Ketabi, Shahin; Kersting, Uwe G.

    2013-01-01

    Ground contact in running is always linked to a minimum amount of slipping, e.g., during the early contact phase when horizontal forces are high compared to vertical forces. Studies have shown altered muscular activation when expecting slips [2-4]. It is not known what the mechanical effect of su...... of such slip episodes are on joint loading or performance. The aim of the present study was to examine the effect of changes in ankle movement on ankle joint loading, muscle activity, and ground reaction forces during linear acceleration....

  9. Measurements of astrophysical reaction rates for radioactive samples

    International Nuclear Information System (INIS)

    Koehler, P.E.; O'Brien, H.A.; Bowman, C.D.

    1987-01-01

    Reaction rates for both big-bang and stellar nucleosynthesis can be obtained from the measurement of (n,p) and (n,γ) cross sections for radioactive nuclei. In the past, large backgrounds associated with the sample activity limited these types of measurements to radioisotopes with very long half lives. The advent of the low-energy, high-intensity neutron source at the Los Alamos Neutron Scattering CEnter (LANSCE) has greatly increased the number of nuclei which can be studied. Results of (n,p) measurements on samples with half lives as short as fifty-three days will be given. The astrophysics to be learned from these data will be discussed. Additional difficulties are encountered when making (n,γ) rather than (n,p) measurements. However, with a properly designed detector, and with the high peak neutron intensities now available, (n,γ) measurements can be made for nuclei with half lives as short as several weeks. Progress on the Los Alamos (n,γ) cross-section measurement program for radioactive samples will be discussed. 25 refs., 3 figs., 1 tab

  10. Sensor Prototype to Evaluate the Contact Force in Measuring with Coordinate Measuring Arms

    Directory of Open Access Journals (Sweden)

    Eduardo Cuesta

    2015-06-01

    Full Text Available This paper describes the design, development and evaluation tests of an integrated force sensor prototype for portable Coordinate Measuring Arms (CMAs or AACMMs. The development is based on the use of strain gauges located on the surface of the CMAs’ hard probe. The strain gauges as well as their cables and connectors have been protected with a custom case, made by Additive Manufacturing techniques (Polyjet 3D. The same method has been selected to manufacture an ergonomic handle that includes trigger mechanics and the electronic components required for synchronizing the trigger signal when probing occurs. The paper also describes the monitoring software that reads the signals in real time, the calibration procedure of the prototype and the validation tests oriented towards increasing knowledge of the forces employed in manual probing. Several experiments read and record the force in real time comparing different ways of probing (discontinuous and continuous contact and measuring different types of geometric features, from single planes to exterior cylinders, cones, or spheres, through interior features. The probing force is separated into two components allowing the influence of these strategies in probe deformation to be known. The final goal of this research is to improve the probing technique, for example by using an operator training programme, allowing extra-force peaks and bad contacts to be minimized or just to avoid bad measurements.

  11. Peak Vertical Ground Reaction Force during Two-Leg Landing: A Systematic Review and Mathematical Modeling

    Directory of Open Access Journals (Sweden)

    Wenxin Niu

    2014-01-01

    Full Text Available Objectives. (1 To systematically review peak vertical ground reaction force (PvGRF during two-leg drop landing from specific drop height (DH, (2 to construct a mathematical model describing correlations between PvGRF and DH, and (3 to analyze the effects of some factors on the pooled PvGRF regardless of DH. Methods. A computerized bibliographical search was conducted to extract PvGRF data on a single foot when participants landed with both feet from various DHs. An innovative mathematical model was constructed to analyze effects of gender, landing type, shoes, ankle stabilizers, surface stiffness and sample frequency on PvGRF based on the pooled data. Results. Pooled PvGRF and DH data of 26 articles showed that the square root function fits their relationship well. An experimental validation was also done on the regression equation for the medicum frequency. The PvGRF was not significantly affected by surface stiffness, but was significantly higher in men than women, the platform than suspended landing, the barefoot than shod condition, and ankle stabilizer than control condition, and higher than lower frequencies. Conclusions. The PvGRF and root DH showed a linear relationship. The mathematical modeling method with systematic review is helpful to analyze the influence factors during landing movement without considering DH.

  12. Running quietly reduces ground reaction force and vertical loading rate and alters foot strike technique.

    Science.gov (United States)

    Phan, Xuan; Grisbrook, Tiffany L; Wernli, Kevin; Stearne, Sarah M; Davey, Paul; Ng, Leo

    2017-08-01

    This study aimed to determine if a quantifiable relationship exists between the peak sound amplitude and peak vertical ground reaction force (vGRF) and vertical loading rate during running. It also investigated whether differences in peak sound amplitude, contact time, lower limb kinematics, kinetics and foot strike technique existed when participants were verbally instructed to run quietly compared to their normal running. A total of 26 males completed running trials for two sound conditions: normal running and quiet running. Simple linear regressions revealed no significant relationships between impact sound and peak vGRF in the normal and quiet conditions and vertical loading rate in the normal condition. t-Tests revealed significant within-subject decreases in peak sound, peak vGRF and vertical loading rate during the quiet compared to the normal running condition. During the normal running condition, 15.4% of participants utilised a non-rearfoot strike technique compared to 76.9% in the quiet condition, which was corroborated by an increased ankle plantarflexion angle at initial contact. This study demonstrated that quieter impact sound is not directly associated with a lower peak vGRF or vertical loading rate. However, given the instructions to run quietly, participants effectively reduced peak impact sound, peak vGRF and vertical loading rate.

  13. Squatting-Related Tibiofemoral Shear Reaction Forces and a Biomechanical Rationale for Femoral Component Loosening

    Directory of Open Access Journals (Sweden)

    Ashvin Thambyah

    2014-01-01

    Full Text Available Previous gait studies on squatting have described a rapid reversal in the direction of the tibiofemoral joint shear reaction force when going into a full weight-bearing deep knee flexion squat. The effects of such a shear reversal have not been considered with regard to the loading demand on knee implants in patients whose activities of daily living require frequent squatting. In this paper, the shear reversal effect is discussed and simulated in a finite element knee implant-bone model, to evaluate the possible biomechanical significance of this effect on femoral component loosening of high flexion implants as reported in the literature. The analysis shows that one of the effects of the shear reversal was a switch between large compressive and large tensile principal strains, from knee extension to flexion, respectively, in the region of the anterior flange of the femoral component. Together with the known material limits of cement and bone, this large mismatch in strains as a function of knee position provides new insight into how and why knee implants may fail in patients who perform frequent squatting.

  14. Ground reaction force analysed with correlation coefficient matrix in group of stroke patients.

    Science.gov (United States)

    Szczerbik, Ewa; Krawczyk, Maciej; Syczewska, Małgorzata

    2014-01-01

    Stroke is the third cause of death in contemporary society and causes many disorders. Clinical scales, ground reaction force (GRF) and objective gait analysis are used for assessment of patient's rehabilitation progress during treatment. The goal of this paper is to assess whether signal correlation coefficient matrix applied to GRF can be used for evaluation of the status of post-stroke patients. A group of patients underwent clinical assessment and instrumented gait analysis simultaneously three times. The difference between components of patient's GRF (vertical, fore/aft, med/lat) and normal ones (reference GRF of healthy subjects) was calculated as correlation coefficient. Patients were divided into two groups ("worse" and "better") based on the clinical functional scale tests done at the beginning of rehabilitation process. The results obtained by these two groups were compared using statistical analysis. An increase of median value of correlation coefficient is observed in all components of GRF, but only in non-paretic leg. Analysis of GRF signal can be helpful in assessment of post-stroke patients during rehabilitation. Improvement in stroke patients was observed in non-paretic leg of the "worse" group. GRF analysis should not be the only tool for objective validation of patient's improvement, but could be used as additional source of information.

  15. The cumulative measure of a force: A unified kinetic theory for rigid-sphere and inverse-square force law interactions

    Directory of Open Access Journals (Sweden)

    Yongbin Chang

    2011-09-01

    Full Text Available By introducing a cutoff on the cumulative measure of a force, a unified kinetic theory is developed for both rigid-sphere and inverse-square force laws. The difference between the two kinds of interactions is characterized by a parameter, γ, which is 1 for rigid-sphere interactions and -3 for inverse-square force law interactions. The quantities governed by γ include the specific reaction rates, kernels, collision frequencies, arbitrarily high orders of transition moments, arbitrarily high orders of Fokker-Planck expansion (also called Kramers-Moyal expansion coefficients, and arbitrarily high orders of energy exchange rates. The cutoff constants are shown to be incomplete gamma functions of different orders. The widely used cutoff constant in plasma physics (usually known as Coulomb logarithm is found to be exactly the zeroth order of the incomplete gamma function. The well known Arrhenius reaction rate formula comes from the first order of the incomplete gamma functions, while the negative first order can be used for fitting the fusion reaction rate between deuterium and tritium.

  16. Development of a Force Measurement Device for Lower-Body Muscular Strength Measuring of Skaters

    Science.gov (United States)

    Kim, Dong Ki; Lee, Jeong Tae

    This paper presents a force measurement system that can measure a lower-body muscular strength of skaters. The precise measurement and analysis of the left and right lower-body strength of skaters is necessary, because a left/right lower-body strength balance is helpful to improve the athletes' performance and to protect them from injury. The system is constructed with a skate sliding board, a couple of sensor-units with load cell, indicator and control box, guard, force pad, and support bracket. The developed force measurement system is calibrated by the calibration setup, and the uncertainty of the force sensing unit on the left is within 0.087% and the uncertainty of the force sensing unit on the right is within 0.109%. In order to check the feasibility of the developed measurement device, a kinematic analysis is conducted with skater. As a result, the subject shows the deviation of left and right of 12.1 N with respect to average strength and 39.1 N with respect to the maximum strength. This evaluation results are reliable enough to make it possible to measure a lower-body muscular strength of skaters. The use of this measurement system will be expected to correct the posture of skaters and record the sports dynamics data for each athlete. It is believed that through the development of this equipment, skaters in elementary, middle, high schools, colleges, and the professional level have the systematic training to compete with world-class skaters.

  17. The Effects of Opposition and Gender on Knee Kinematics and Ground Reaction Force during Landing from Volleyball Block Jumps

    Science.gov (United States)

    Hughes, Gerwyn; Watkins, James; Owen, Nick

    2010-01-01

    The aim of this study was to examine the effect of opposition and gender on knee kinematics and ground reaction force during landing from a volleyball block jump. Six female and six male university volleyball players performed two landing tasks: (a) an unopposed and (b) an opposed volleyball block jump and landing. A 12-camera motion analysis…

  18. Aerosol Direct Radiative Forcing and Forcing Efficiencies at Surface from the shortwave Irradiance Measurements in Abu Dhabi, UAE

    Science.gov (United States)

    Beegum S, N.; Ben Romdhane, H.; Ghedira, H.

    2013-12-01

    Atmospheric aerosols are known to affect the radiation balance of the Earth-Atmospheric system directly by scattering and absorbing the solar and terrestrial radiation, and indirectly by affecting the lifetime and albedo of the clouds. Continuous and simultaneous measurements of short wave global irradiance in combination with synchronous spectral aerosol optical depth (AOD) measurements (from 340 nm to 1640 nm in 8 channels), for a period of 1 year from June 2012 to May 2013, were used for the determination of the surface direct aerosol radiative forcing and forcing efficiencies under cloud free conditions in Abu Dhabi (24.42°N, 54.61o E, 7m MSL), a coastal location in United Arab Emirates (UAE) in the Arabian Peninsula. The Rotating Shadow band Pyranometer (RSP, LI-COR) was used for the irradiance measurements (in the spectral region 400-1100 nm), whereas the AOD measurements were carried out using CIMEL Sunphotometer (CE 318-2, under AERONET program). The differential method, which is neither sensitive to calibration uncertainties nor model assumptions, has been employed for estimating forcing efficiencies from the changes in the measured fluxes. The forcing efficiency, which quantifies the net change in irradiance per unit change in AOD, is an appropriate parameter for the characterization of the aerosol radiative effects even if the microphysical and optical properties of the aerosols are not completely understood. The corresponding forcing values were estimated from the forcing efficiencies. The estimated radiative forcing and forcing efficiencies exhibited strong monthly variations. The forcing efficiencies (absolute magnitudes) were highest during March, and showed continuous decrease thereafter to reach the lowest value during September. In contrast, the forcing followed a slightly different pattern of variability, with the highest solar dimming during April ( -60 W m-2) and the minimum during February ( -20 W m-2). The results indicate that the aerosol

  19. Measurement of charmed particle production in hadronic reactions

    CERN Multimedia

    2002-01-01

    The aim of the experiment is to measure the production cross-section for charmed particles in hadronic reactions, study their production mechanism, and search for excited charmed hadrons.\\\\ \\\\ Charmed Mesons and Baryons will be measured in $\\pi$ and $p$ interactions on Beryllium between 100 and 200 GeV/c. The trigger will be on an electron from the leptonic decay of one charmed particle by signals from the Cerenkov counter (Ce), the electron trigger calorimeter (eCal), scintillation counters, and proportional wire chambers. The accompanying charmed particle will be measured via its hadronic decay in a two-stage magnetic spectrometer with drift chambers (arms 2, 3a, 3b, 3c), two large-area multicell Cerenkov counters (C2, C3) and a large-area shower counter ($\\gamma$-CAL). The particles which can be measured and identified include $\\gamma, e, \\pi^{\\pm}, \\pi^{0}, K^{\\pm}, p, \\bar{p}$ so that a large number of hadronic decay modes of charmed particles can be studied. \\\\ \\\\ A silicon counter telescope with 5 $\\m...

  20. Measurement of hydrogen in BCN films by nuclear reaction analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yasui, Haruyuki; Hirose, Yukio; Sasaki, Toshihiko [Kanazawa Univ. (Japan); Awazu, Kaoru [Industrial Research Inst., of Ishikawa, Kanazawa (Japan); Naramoto, Hiroshi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2001-07-01

    Hydrogen is a very common contaminant in carbon films. It can strongly influence on mechanical, physical and chemical properties of the films. The analysis of hydrogen is therefore a crucial problem produce the films with the properties required. Ion beam techniques using nuclear reactions are effective for the quantitative determination of hydrogen concentration. A specially designed spectrometer is employed for the detailed determination of hydrogen concentrations by detecting 4.43MeV {gamma}-rays from the resonant nuclear reactions {sup 1}H({sup 15}N, {alpha}{gamma}){sup 12}C at the 6.385MeV. In this study, the BCN films were formed on silicon substrate by ion beam assisted deposition (IBAD), in which boron and carbon were deposited by electron beam heating of B{sub 4}C solid and nitrogen was supplied by ion implantation simultaneously. The concentrations of hydrogen in BCN films were measured using RNRA. The mechanical properties of BCN films were evaluated using an ultra-micro-hardness tester. It was confirmed that the hardness of BCN films increased with increasing the concentration of hydrogen. (author)

  1. Measurements of the Casimir-Lifshitz force in fluids: The effect of electrostatic forces and Debye screening

    Science.gov (United States)

    Munday, J. N.; Capasso, Federico; Parsegian, V. Adrian; Bezrukov, Sergey M.

    2008-09-01

    We present detailed measurements of the Casimir-Lifshitz force between two gold surfaces (a sphere and a plate) immersed in ethanol and study the effect of residual electrostatic forces, which are dominated by static fields within the apparatus and can be reduced with proper shielding. Electrostatic forces are further reduced by Debye screening through the addition of salt ions to the liquid. Additionally, the salt leads to a reduction of the Casimir-Lifshitz force by screening the zero-frequency contribution to the force; however, the effect is small between gold surfaces at the measured separations and within experimental error. An improved calibration procedure is described and compared with previous methods. Finally, the experimental results are compared with Lifshitz’s theory and found to be consistent for the materials used in the experiment.

  2. Electromotive force measurement of lanthanides in Bi solution

    International Nuclear Information System (INIS)

    Sheng, Jiawei; Yamana, Hajimu; Moriyama, Hirotake

    2000-01-01

    The thermodynamic properties of Tb, Dy and Ho dissolved in liquid Bi were determined by the electromotive force (EMF) measurement method. The EMF of the following galvanic cell was measured in the range of 500-800degC over a wide range of solute concentration. Ln(solid)|KCl-LiCl|Ln-Bi (solution) There was observed a linear relationship between the EMFs and the lanthanide (Ln) concentrations in liquid Bi phase at a constant temperature, which agreed with the Nernst's equation. The obtained activity coefficients of lanthanides in liquid Bi solution were almost constant at a fixed temperature condition. Temperature effects on the activity coefficients could be expressed by the following equation: log γ=a+b/T, where a and b are experimental constants which correspond to the entropy and enthalpy of the formation of Ln-Bi compound in the melt, respectively. The thermodynamic quantities obtained were discussed in terms of their systematics along the 4f series. (author)

  3. The oxygen evolution reaction on cobalt Part I. Reaction order experiments and impedance measurements

    NARCIS (Netherlands)

    Kobussen, A.G.C.; Willems, H.; Wit, J.H.W. de; Broers, G.H.J.

    1984-01-01

    It was found that the oxygen evolution reaction on cobalt in concentrated KOH solutions can be described differently for low and high overpotentials. In the overpotential range from 150 to 280 mV, the reaction has a Tafel slope of approximately 40 mV and a reaction order with respect to the KOH

  4. Measuring the complex behavior of the SO2 oxidation reaction

    Directory of Open Access Journals (Sweden)

    Muhammad Shahzad

    2015-09-01

    Full Text Available The two step reversible chemical reaction involving five chemical species is investigated. The quasi equilibrium manifold (QEM and spectral quasi equilibrium manifold (SQEM are used for initial approximation to simplify the mechanisms, which we want to utilize in order to investigate the behavior of the desired species. They show a meaningful picture, but for maximum clarity, the investigation method of invariant grid (MIG is employed. These methods simplify the complex chemical kinetics and deduce low dimensional manifold (LDM from the high dimensional mechanism. The coverage of the species near equilibrium point is investigated and then we shall discuss moving along the equilibrium of ODEs. The steady state behavior is observed and the Lyapunov function is utilized to study the stability of ODEs. Graphical results are used to describe the physical aspects of measurements.

  5. Functional knee brace use effect on peak vertical ground reaction forces during drop jump landing.

    Science.gov (United States)

    Rishiraj, Neetu; Taunton, Jack E; Lloyd-Smith, Robert; Regan, William; Niven, Brian; Woollard, Robert

    2012-12-01

    The aim of the study was to investigate the landing strategies used by non-injured athletes while wearing functional knee braces (FKB, BR condition) during a drop jump task compared with non-injured, non-braced (NBR condition) subjects and also to ascertain whether accommodation to a FKB was possible by non-injured BR subjects. Twenty-three healthy male provincial and national basketball and field hockey athletes (age, 19.4 ± 3.0 years) were tested. Each subject was provided with a custom-fitted FKB. Five NBR testing sessions were performed over 3 days followed by five BR testing sessions also over 3 days, for a total of 17.5 h of testing per condition. Each subject performed eight trials of the drop jump task during each testing session per condition. Single-leg peak vertical ground reaction forces (PVGRF) and the time to PVGRF were recorded for each NBR and BR trail. The BR group mean PVGRF at landing was significantly lower (1,628 ± 405 N, 2.1 ± 0.5 BW versus 1,715 ± 403 N, 2.2 ± 0.5 BW, F (1,22) = 6.83, P = 0.01) compared with NBR subjects, respectively. The group mean time to PVGRF was not statistically longer during the BR condition (F (1,22) = 0.967, P = 0.3). Further, an accommodation trend was noted as percent performance difference decreased with continued FKB use. The significantly lower group mean PVGRF while using a FKB could keep traumatic forces from reaching the ACL until the active neuromuscular restraints are activated to provide protection to the knee joint ligaments. Also, accommodation to FKB is possible after approximately 14.0 h of brace use. The results of this paper will assist clinicians in providing information to their patients regarding a FKB ability to offer protection to an ACL-deficient knee or to address concerns about early muscle fatigue, energy expenditure, heart rate, and decrease in performance level. Prospective study, Level I.

  6. Reaction Force/Torque Sensing in a Master-Slave Robot System without Mechanical Sensors

    Directory of Open Access Journals (Sweden)

    Kyoko Shibata

    2010-07-01

    Full Text Available In human-robot cooperative control systems, force feedback is often necessary in order to achieve high precision and high stability. Usually, traditional robot assistant systems implement force feedback using force/torque sensors. However, it is difficult to directly mount a mechanical force sensor on some working terminals, such as in applications of minimally invasive robotic surgery, micromanipulation, or in working environments exposed to radiation or high temperature. We propose a novel force sensing mechanism for implementing force feedback in a master-slave robot system with no mechanical sensors. The system consists of two identical electro-motors with the master motor powering the slave motor to interact with the environment. A bimanual coordinated training platform using the new force sensing mechanism was developed and the system was verified in experiments. Results confirm that the proposed mechanism is capable of achieving bilateral force sensing and mirror-image movements of two terminals in two reverse control directions.

  7. Probing the three-nucleon force using nucleon-deuteron breakup reactions

    International Nuclear Information System (INIS)

    Howell, C.R.; Lambert, J.M.; Witala, H.

    1995-01-01

    Results of our recent kinematically complete cross-section measurements of the space-star and coplanar-star configurations in n-d breakup at 13.0 MeV are reported. The experimental setup and details of the analysis are described. The new data for the space-star configuration are in good agreement with previous n-d data but differ significantly from both ''exact'' n-d calculations and p-d data. In contrast, the new coplanar-star data are in fair agreement with the calculations but are in gross disagreement with previous n-d data. The implications of these data for three-nucleon forces are discussed. (orig.)

  8. Probing the three-nucleon force using nucleon-deuteron breakup reactions

    Energy Technology Data Exchange (ETDEWEB)

    Howell, C.R. [Duke Univ., Durham, NC (United States). Dept. of Physics; Setze, H.R. [Duke Univ., Durham, NC (United States). Dept. of Physics; Braun, R.T. [Duke Univ., Durham, NC (United States). Dept. of Physics; Gonzalez Trotter, D.E. [Duke Univ., Durham, NC (United States). Dept. of Physics; Hussein, A.H. [Duke Univ., Durham, NC (United States). Dept. of Physics; Roper, C.D. [Duke Univ., Durham, NC (United States). Dept. of Physics; Salinas, F. [Duke Univ., Durham, NC (United States). Dept. of Physics; Slaus, I. [Duke Univ., Durham, NC (United States). Dept. of Physics; Tornow, W. [Duke Univ., Durham, NC (United States). Dept. of Physics; Vlahovic, B. [Duke Univ., Durham, NC (United States). Dept. of Physics; Walter, R.L. [Duke Univ., Durham, NC (United States). Dept. of Physics; Mertens, G. [Tuebingen Univ. (Germany); Lambert, J.M. [Department of Physics, Georgetown University, Washington, DC 20057 (United States); Witala, H. [Institute of Physics, Jagellonian University, Reymonta 4, PL-30059 Cracow (Poland)

    1995-05-01

    Results of our recent kinematically complete cross-section measurements of the space-star and coplanar-star configurations in n-d breakup at 13.0 MeV are reported. The experimental setup and details of the analysis are described. The new data for the space-star configuration are in good agreement with previous n-d data but differ significantly from both ``exact`` n-d calculations and p-d data. In contrast, the new coplanar-star data are in fair agreement with the calculations but are in gross disagreement with previous n-d data. The implications of these data for three-nucleon forces are discussed. (orig.).

  9. Measurement of Forces and Moments Transmitted to the Residual Limb

    Science.gov (United States)

    2010-10-01

    Interface Biomechanical Correlate Force X Anterior-Posterior Force Perpendicular to Pylon Anterior-Posterior Force on Limb Braking and Propulsion...to produce noticeable pressure for level walking, going up stairs , up ramps, walking in a circle with the prosthetic foot inside and outside, and...0.3 Up Stairs Notch Throug hout 0.5 Notch Throug hout 0.3 Down Stairs Distal Tibia Popliteal Throughout Throughout 1 1 Distal Tibia Throughout

  10. NUMBER OF SUCCESSIVE CYCLES NECESSARY TO ACHIEVE STABILITY OF SELECTED GROUND REACTION FORCE VARIABLES DURING CONTINUOUS JUMPING

    Directory of Open Access Journals (Sweden)

    Jasmes M.W. Brownjohn

    2009-12-01

    Full Text Available Because of inherent variability in all human cyclical movements, such as walking, running and jumping, data collected across a single cycle might be atypical and potentially unable to represent an individual's generalized performance. The study described here was designed to determine the number of successive cycles due to continuous, repetitive countermovement jumping which a test subject should perform in a single experimental session to achieve stability of the mean of the corresponding continuously measured ground reaction force (GRF variables. Seven vertical GRF variables (period of jumping cycle, duration of contact phase, peak force amplitude and its timing, average rate of force development, average rate of force relaxation and impulse were extracted on the cycle-by-cycle basis from vertical jumping force time histories generated by twelve participants who were jumping in response to regular electronic metronome beats in the range 2-2.8 Hz. Stability of the selected GRF variables across successive jumping cycles was examined for three jumping rates (2, 2.4 and 2.8 Hz using two statistical methods: intra-class correlation (ICC analysis and segmental averaging technique (SAT. Results of the ICC analysis indicated that an average of four successive cycles (mean 4.5 ± 2.7 for 2 Hz; 3.9 ± 2.6 for 2.4 Hz; 3.3 ± 2.7 for 2.8 Hz were necessary to achieve maximum ICC values. Except for jumping period, maximum ICC values took values from 0.592 to 0.991 and all were significantly (p < 0.05 different from zero. Results of the SAT revealed that an average of ten successive cycles (mean 10.5 ± 3.5 for 2 Hz; 9.2 ± 3.8 for 2.4 Hz; 9.0 ± 3.9 for 2.8 Hz were necessary to achieve stability of the selected parameters using criteria previously reported in the literature. Using 10 reference trials, the SAT required standard deviation criterion values of 0.49, 0.41 and 0.55 for 2 Hz, 2.4 Hz and 2.8 Hz jumping rates, respectively, in order to approximate

  11. Exploring Heat Stress Relief Measures among the Australian Labour Force.

    Science.gov (United States)

    Zander, Kerstin K; Mathew, Supriya; Garnett, Stephen T

    2018-02-26

    Australia experiences frequent heat waves and generally high average temperatures throughout the continent with substantial impacts on human health and the economy. People adapt to heat by adopting various relief measures in their daily lives including changing their behaviour. Many labour intensive outdoor industries implement standards for heat stress management for their workforce. However, little is known about how people cope with heat at their workplaces apart from studies targeting some specific industries where labourers are exposed to extreme heat. Here, we analysed responses from 1719 people in the Australian labour force to self-reported heat stress and associated coping mechanisms. Three quarters of respondents experienced heat stress at their workplace with fatigue and headache being the two most frequently stated symptoms. Almost all of those who were affected by heat would hydrate (88%), 67% would cool, and 44% would rest as a strategy for coping with heat. About 10% intended to change their jobs because of heat stress in the workplace. We found differences in heat relief measures across gender, education, health, level of physical intensity of job, and time spent working outside. People working in jobs that were not very demanding physically were more likely to choose cooling down as a relief measure, while those in labour intensive jobs and jobs that required considerable time outside were more likely to rest. This has potential consequences for their productivity and work schedules. Heat affects work in Australia in many types of industry with impact dependent on workforce acclimatisation, yet public awareness and work relief plans are often limited to outdoor and labour intensive industries. Industries and various levels of government in all sectors need to implement standards for heat management specific to climate zones to help people cope better with high temperatures as well as plan strategies in anticipation of projected temperature

  12. Exploring Heat Stress Relief Measures among the Australian Labour Force

    Directory of Open Access Journals (Sweden)

    Kerstin K. Zander

    2018-02-01

    Full Text Available Australia experiences frequent heat waves and generally high average temperatures throughout the continent with substantial impacts on human health and the economy. People adapt to heat by adopting various relief measures in their daily lives including changing their behaviour. Many labour intensive outdoor industries implement standards for heat stress management for their workforce. However, little is known about how people cope with heat at their workplaces apart from studies targeting some specific industries where labourers are exposed to extreme heat. Here, we analysed responses from 1719 people in the Australian labour force to self-reported heat stress and associated coping mechanisms. Three quarters of respondents experienced heat stress at their workplace with fatigue and headache being the two most frequently stated symptoms. Almost all of those who were affected by heat would hydrate (88%, 67% would cool, and 44% would rest as a strategy for coping with heat. About 10% intended to change their jobs because of heat stress in the workplace. We found differences in heat relief measures across gender, education, health, level of physical intensity of job, and time spent working outside. People working in jobs that were not very demanding physically were more likely to choose cooling down as a relief measure, while those in labour intensive jobs and jobs that required considerable time outside were more likely to rest. This has potential consequences for their productivity and work schedules. Heat affects work in Australia in many types of industry with impact dependent on workforce acclimatisation, yet public awareness and work relief plans are often limited to outdoor and labour intensive industries. Industries and various levels of government in all sectors need to implement standards for heat management specific to climate zones to help people cope better with high temperatures as well as plan strategies in anticipation of projected

  13. Measurement of the tensile forces during bone lengthening.

    Science.gov (United States)

    Ohnishi, Isao; Kurokawa, Takahide; Sato, Wakyo; Nakamura, Kozo

    2005-05-01

    The purpose of this study was to investigate the effects of lengthening frequency on mechanical environment in limb lengthening. Tensile forces were continuously monitored using a load sensor attached to a unilateral external fixator. Twenty patients were monitored. Ten patients were with acquired femoral shortening, and five of them underwent quasi-continuous lengthening of 1440 steps per day, and the other five received step lengthening twice a day. The other 10 patients were with achondropalsia. Five of them underwent the same quasi-continuous lengthening, and the other five received the same step lengthening. The circadian change and the daily course of the tensile forces were assessed and compared between quasi-continuous lengthening and step lengthening. As for circadian change, an acute increase in the force took place simultaneously with each step of lengthening in the step-lengthening group, but very little change of the baseline force level was seen during quasi-continuous lengthening. As for daily course of the tensile force, it increased almost linearly in both lengthening frequency groups in the initial stage of lengthening. No significant difference of the average force increment rate in this phase was recognized between the quasi-continuous and step lengthening groups irrespective of the etiologies. The lengthening frequency greatly affected the circadian change of the tensile force, but did not affect the increment rate of the force in the linear phase.

  14. Force measuring valve assemblies, systems including such valve assemblies and related methods

    Science.gov (United States)

    DeWall, Kevin George [Pocatello, ID; Garcia, Humberto Enrique [Idaho Falls, ID; McKellar, Michael George [Idaho Falls, ID

    2012-04-17

    Methods of evaluating a fluid condition may include stroking a valve member and measuring a force acting on the valve member during the stroke. Methods of evaluating a fluid condition may include measuring a force acting on a valve member in the presence of fluid flow over a period of time and evaluating at least one of the frequency of changes in the measured force over the period of time and the magnitude of the changes in the measured force over the period of time to identify the presence of an anomaly in a fluid flow and, optionally, its estimated location. Methods of evaluating a valve condition may include directing a fluid flow through a valve while stroking a valve member, measuring a force acting on the valve member during the stroke, and comparing the measured force to a reference force. Valve assemblies and related systems are also disclosed.

  15. Solvent effects and potential of mean force study of the SN2 reaction of CH3+CN‑ in water

    Science.gov (United States)

    Li, Chen; Liu, Peng; Li, Yongfang; Wang, Dunyou

    2018-03-01

    We used a combined quantum mechanics and molecular mechanics (QM/MM) method to investigate the solvent effects and potential of mean force of the CH3F+CN‑ reaction in water. Comparing to gas phase, the water solution substantially affects the structures of the stationary points along the reaction path. We quantitatively obtained the solvent effects’ contributions to the reaction: 1.7 kcal/mol to the activation barrier and ‑26.0 kcal/mol to the reaction free energy. The potential mean of force calculated with the density functional theory/MM theory has a barrier height at 19.7 kcal/mol, consistent with the experimental result at 23.0 kcal/mol; the calculated reaction free energy at ‑43.5 kcal/mol is also consistent with the one estimated based on the gas-phase data at ‑39.7 kcal/mol. Project supported by the National Natural Science Foundation of China (Grant No. 11774206) and Taishan Scholarship Fund from Shandong Province, China.

  16. The Comparison of Vertical Ground Reaction Force during Forward and Backward Walking among Professional Male Karatekas with Genu Varum and Normal Knees

    Directory of Open Access Journals (Sweden)

    Heydar Sadeghi

    2017-06-01

    Conclusion: Based on the results of present study, genu varum can be considered as an effective factor on vertical ground reaction force (as predictor factor of musculoskeletal injuries among the Karate professionals, and backward walking can cause a change in vertical ground reaction force more than forward walking does.

  17. Depletion interaction measured by colloidal probe atomic force microscopy

    NARCIS (Netherlands)

    Wijting, W.K.; Knoben, W.; Besseling, N.A.M.; Leermakers, F.A.M.; Cohen Stuart, M.A.

    2004-01-01

    We investigated the depletion interaction between stearylated silica surfaces in cyclohexane in the presence of dissolved polydimethylsiloxane by means of colloidal probe atomic force microscopy. We found that the range of the depletion interaction decreases with increasing concentration.

  18. Effects of fatigue on bilateral ground reaction force asymmetries during the squat exercise.

    Science.gov (United States)

    Hodges, Stephanie J; Patrick, Ryan J; Reiser, Raoul F

    2011-11-01

    Physical performance and injury risk have been related to functional asymmetries of the lower extremity. The effect of fatigue on asymmetries is not well understood. The goal of this investigation was to examine asymmetries during fatiguing repetitions and sets of the free-weight barbell back squat exercise. Seventeen healthy recreationally trained men and women (age = 22.3 ± 2.5 years; body mass = 73.4 ± 13.8 kg; squat 8 repetition maximum [8RM] = 113 ± 35% body mass [mean ± SD]) performed 5 sets of 8 repetitions with 90% 8RM while recording bilateral vertical ground reaction force (GRFv). The GRFv asymmetry during the first 2 (R1 and R2) and the last 2 (R7 and R8) repetitions of each set was calculated by subtracting the % load on the right foot from that of the left foot. Most subjects placed more load on their left foot (also their preferred non-kicking foot). Average absolute asymmetry level across all sets was 4.3 ± 2.5 and 3.6 ± 2.3% for R1 and R2 and R7 and R8, respectively. There were no effects of fatigue on GRFv asymmetries in whole-group analysis (n = 17). However, when initially highly symmetric subjects (±1.7% Left-Right) were removed, average absolute GRFv asymmetry dropped from the beginning to the end of a set (n = 12, p = 0.044) as did peak instantaneous GRFv asymmetry when exploring general shifts toward the left or right leg (n = 12, p = 0.042). The GRFv asymmetries were highly repeatable for 8 subjects that repeated the protocol (Cronbach's α ≥ 0.733, p ≤ 0.056). These results suggest that functional asymmetries, though low, are present in healthy people during the squat exercise and remain consistent. Asymmetries do not increase with fatigue, potentially even decreasing, suggesting that healthy subjects load limbs similarly as fatigue increases, exposing each to similar training stimuli.

  19. Effects of Prophylactic Ankle Supports on Vertical Ground Reaction Force During Landing: A Meta-Analysis

    Directory of Open Access Journals (Sweden)

    Wenxin Niu, Tienan Feng, Lejun Wang, Chenghua Jiang, Ming Zhang

    2016-03-01

    Full Text Available There has been much debate on how prophylactic ankle supports (PASs may influence the vertical ground reaction force (vGRF during landing. Therefore, the primary aims of this meta-analysis were to systematically review and synthesize the effect of PASs on vGRF, and to understand how PASs affect vGRF peaks (F1, F2 and the time from initial contact to peak loading (T1, T2 during landing. Several key databases, including Scopus, Cochrane, Embase, PubMed, ProQuest, Medline, Ovid, Web of Science, and the Physical Activity Index, were used for identifying relevant studies published in English since inception to April 1, 2015. The computerized literature search and cross-referencing the citation list of the articles yielded 3,993 articles. Criteria for inclusion required that 1 the study was conducted on healthy adults; 2 the subject number and trial number were known; 3 the subjects performed landing with and without PAS; 4 the landing movement was in the sagittal plane; 5 the comparable vGRF parameters were reported; and 6 the F1 and F2 must be normalized to the subject’s body weight. After the removal of duplicates and irrelevant articles, 6, 6, 15 and 11 studies were respectively pooled for outcomes of F1, T1, F2 and T2. This study found a significantly increased F2 (.03 BW, 95% CI: .001, .05 and decreased T1 (-1.24 ms, 95% CI: -1.77, -.71 and T2 (-3.74 ms, 95% CI: -4.83, -2.65 with the use of a PAS. F1 was not significantly influenced by the PAS. Heterogeneity was present in some results, but there was no evidence of publication bias for any outcome. These changes represented deterioration in the buffering characteristics of the joint. An ideal PAS design should limit the excessive joint motion of ankle inversion, while allowing a normal range of motion, especially in the sagittal plane.

  20. Standard practice of calibration of force-measuring instruments for verifying the force indication of testing machines

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2006-01-01

    1.1 The purpose of this practice is to specify procedures for the calibration of force-measuring instruments. Procedures are included for the following types of instruments: 1.1.1 Elastic force-measuring instruments, and 1.1.2 Force-multiplying systems, such as balances and small platform scales. Note 1Verification by deadweight loading is also an acceptable method of verifying the force indication of a testing machine. Tolerances for weights for this purpose are given in Practices E 4; methods for calibration of the weights are given in NIST Technical Note 577, Methods of Calibrating Weights for Piston Gages. 1.2 The values stated in SI units are to be regarded as the standard. Other metric and inch-pound values are regarded as equivalent when required. 1.3 This practice is intended for the calibration of static force measuring instruments. It is not applicable for dynamic or high speed force calibrations, nor can the results of calibrations performed in accordance with this practice be assumed valid for...

  1. Stern potential and Debye length measurements in dilute ionic solutions with electrostatic force microscopy

    International Nuclear Information System (INIS)

    Kumar, Bharat; Crittenden, Scott R

    2013-01-01

    We demonstrate the ability to measure Stern potential and Debye length in dilute ionic solution with atomic force microscopy. We develop an analytic expression for the second harmonic force component of the capacitive force in an ionic solution from the linearized Poisson–Boltzmann equation. This allows us to calibrate the AFM tip potential and, further, obtain the Stern potential of sample surfaces. In addition, the measured capacitive force is independent of van der Waals and double layer forces, thus providing a more accurate measure of Debye length. (paper)

  2. Stern potential and Debye length measurements in dilute ionic solutions with electrostatic force microscopy.

    Science.gov (United States)

    Kumar, Bharat; Crittenden, Scott R

    2013-11-01

    We demonstrate the ability to measure Stern potential and Debye length in dilute ionic solution with atomic force microscopy. We develop an analytic expression for the second harmonic force component of the capacitive force in an ionic solution from the linearized Poisson-Boltzmann equation. This allows us to calibrate the AFM tip potential and, further, obtain the Stern potential of sample surfaces. In addition, the measured capacitive force is independent of van der Waals and double layer forces, thus providing a more accurate measure of Debye length.

  3. Locking of Turing patterns in the chlorine dioxide-iodine-malonic acid reaction with one-dimensional spatial periodic forcing.

    Science.gov (United States)

    Dolnik, Milos; Bánsági, Tamás; Ansari, Sama; Valent, Ivan; Epstein, Irving R

    2011-07-21

    We use the photosensitive chlorine dioxide-iodine-malonic acid reaction-diffusion system to study wavenumber locking of Turing patterns with spatial periodic forcing. Wavenumber-locked stripe patterns are the typical resonant structures that labyrinthine patterns exhibit in response to one-dimensional forcing by illumination when images of stripes are projected on a working medium. Our experimental results reveal that segmented oblique, hexagonal and rectangular patterns can also be obtained. However, these two-dimensional resonant structures only develop in a relatively narrow range of forcing parameters, where the unforced stripe pattern is in close proximity to the domain of hexagonal patterns. Numerical simulations based on a model that incorporates the forcing by illumination using an additive term reproduce well the experimental observations. These findings confirm that additive one-dimensional forcing can generate a two-dimensional resonant response. However, such a response is considerably less robust than the effect of multiplicative forcing. This journal is © the Owner Societies 2011

  4. Reorganization energy upon charging a single molecule on an insulator measured by atomic force microscopy

    Science.gov (United States)

    Fatayer, Shadi; Schuler, Bruno; Steurer, Wolfram; Scivetti, Ivan; Repp, Jascha; Gross, Leo; Persson, Mats; Meyer, Gerhard

    2018-05-01

    Intermolecular single-electron transfer on electrically insulating films is a key process in molecular electronics1-4 and an important example of a redox reaction5,6. Electron-transfer rates in molecular systems depend on a few fundamental parameters, such as interadsorbate distance, temperature and, in particular, the Marcus reorganization energy7. This crucial parameter is the energy gain that results from the distortion of the equilibrium nuclear geometry in the molecule and its environment on charging8,9. The substrate, especially ionic films10, can have an important influence on the reorganization energy11,12. Reorganization energies are measured in electrochemistry13 as well as with optical14,15 and photoemission spectroscopies16,17, but not at the single-molecule limit and nor on insulating surfaces. Atomic force microscopy (AFM), with single-charge sensitivity18-22, atomic-scale spatial resolution20 and operable on insulating films, overcomes these challenges. Here, we investigate redox reactions of single naphthalocyanine (NPc) molecules on multilayered NaCl films. Employing the atomic force microscope as an ultralow current meter allows us to measure the differential conductance related to transitions between two charge states in both directions. Thereby, the reorganization energy of NPc on NaCl is determined as (0.8 ± 0.2) eV, and density functional theory (DFT) calculations provide the atomistic picture of the nuclear relaxations on charging. Our approach presents a route to perform tunnelling spectroscopy of single adsorbates on insulating substrates and provides insight into single-electron intermolecular transport.

  5. The FORCE Fitness Profile--Adding a Measure of Health-Related Fitness to the Canadian Armed Forces Operational Fitness Evaluation.

    Science.gov (United States)

    Gagnon, Patrick; Spivock, Michael; Reilly, Tara; Mattie, Paige; Stockbrugger, Barry

    2015-11-01

    In 2013, the Canadian Armed Forces (CAF) implemented the Fitness for Operational Requirements of Canadian Armed Forces Employment (FORCE), a field expedient fitness test designed to predict the physical requirements of completing common military tasks. Given that attaining this minimal physical fitness standard may not represent a challenge to some personnel, a fitness incentive program was requested by the chain of command to recognize and reward fitness over and above the minimal standard. At the same time, it was determined that the CAF would benefit from a measure of general health-related fitness, in addition to this measure of operational fitness. The resulting incentive program structure is based on gender and 8 age categories. The results on the 4 elements of the FORCE evaluation were converted to a point scale from which normative scores were derived, where the median score corresponds to the bronze level, and silver, gold, and platinum correspond to a score which is 1, 2, and 3 SDs above this median, respectively. A suite of rewards including merit board point toward promotions and recognition on the uniform and material rewards was developed. A separate group rewards program was also tabled, to recognize achievements in fitness at the unit level. For general fitness, oxygen capacity was derived from FORCE evaluation results and combined with a measure of abdominal circumference. Fitness categories were determined based on relative risks of mortality and morbidity for each age and gender group. Pilot testing of this entire program was performed with 624 participants to assess participants' reactions to the enhanced test, and also to verify logistical aspects of the electronic data capture, calculation, and transfer system. The newly dubbed fitness profile program was subsequently approved by the senior leadership of the CAF and is scheduled to begin a phased implementation in June 2015.

  6. Gender difference in older adult's utilization of gravitational and ground reaction force in regulation of angular momentum during stair descent.

    Science.gov (United States)

    Singhal, Kunal; Kim, Jemin; Casebolt, Jeffrey; Lee, Sangwoo; Han, Ki-Hoon; Kwon, Young-Hoo

    2015-06-01

    Angular momentum of the body is a highly controlled quantity signifying stability, therefore, it is essential to understand its regulation during stair descent. The purpose of this study was to investigate how older adults use gravity and ground reaction force to regulate the angular momentum of the body during stair descent. A total of 28 participants (12 male and 16 female; 68.5 years and 69.0 years of mean age respectively) performed stair descent from a level walk in a step-over-step manner at a self-selected speed over a custom made three-step staircase with embedded force plates. Kinematic and force data were used to calculate angular momentum, gravitational moment, and ground reaction force moment about the stance foot center of pressure. Women show a significantly greater change in normalized angular momentum (0.92Nms/Kgm; p=.004) as compared to men (0.45Nms/Kgm). Women produce higher normalized GRF (p=.031) during the double support phase. The angular momentum changes show largest backward regulation for Step 0 and forward regulation for Step 2. This greater difference in overall change in the angular momentum in women may explain their increased risk of fall over the stairs. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Calculation of reaction forces in the boiler supports using the method of equivalent stiffness of membrane wall.

    Science.gov (United States)

    Sertić, Josip; Kozak, Dražan; Samardžić, Ivan

    2014-01-01

    The values of reaction forces in the boiler supports are the basis for the dimensioning of bearing steel structure of steam boiler. In this paper, the application of the method of equivalent stiffness of membrane wall is proposed for the calculation of reaction forces. The method of equalizing displacement, as the method of homogenization of membrane wall stiffness, was applied. On the example of "Milano" boiler, using the finite element method, the calculation of reactions in the supports for the real geometry discretized by the shell finite element was made. The second calculation was performed with the assumption of ideal stiffness of membrane walls and the third using the method of equivalent stiffness of membrane wall. In the third case, the membrane walls are approximated by the equivalent orthotropic plate. The approximation of membrane wall stiffness is achieved using the elasticity matrix of equivalent orthotropic plate at the level of finite element. The obtained results were compared, and the advantages of using the method of equivalent stiffness of membrane wall for the calculation of reactions in the boiler supports were emphasized.

  8. Calculation of Reaction Forces in the Boiler Supports Using the Method of Equivalent Stiffness of Membrane Wall

    Directory of Open Access Journals (Sweden)

    Josip Sertić

    2014-01-01

    Full Text Available The values of reaction forces in the boiler supports are the basis for the dimensioning of bearing steel structure of steam boiler. In this paper, the application of the method of equivalent stiffness of membrane wall is proposed for the calculation of reaction forces. The method of equalizing displacement, as the method of homogenization of membrane wall stiffness, was applied. On the example of “Milano” boiler, using the finite element method, the calculation of reactions in the supports for the real geometry discretized by the shell finite element was made. The second calculation was performed with the assumption of ideal stiffness of membrane walls and the third using the method of equivalent stiffness of membrane wall. In the third case, the membrane walls are approximated by the equivalent orthotropic plate. The approximation of membrane wall stiffness is achieved using the elasticity matrix of equivalent orthotropic plate at the level of finite element. The obtained results were compared, and the advantages of using the method of equivalent stiffness of membrane wall for the calculation of reactions in the boiler supports were emphasized.

  9. Exciplexes versus Loose Ion Pairs: How Does the Driving Force Impact the Initial Product Ratio of Photoinduced Charge Separation Reactions?

    Science.gov (United States)

    2014-01-01

    Many donor–acceptor systems can undergo a photoinduced charge separation reaction, yielding loose ion pairs (LIPs). LIPs can be formed either directly via (distant) electron transfer (ET) or indirectly via the dissociation of an initially formed exciplex or tight ion pair. Establishing the prevalence of one of the reaction pathways is challenging because differentiating initially formed exciplexes from LIPs is difficult due to similar spectroscopic footprints. Hence, no comprehensive reaction model has been established for moderately polar solvents. Here, we employ an approach based on the time-resolved magnetic field effect (MFE) of the delayed exciplex luminescence to distinguish the two reaction channels. We focus on the effects of the driving force of ET and the solvent permittivity. We show that, surprisingly, the exciplex channel is significant even for an exergonic ET system with a free energy of ET of −0.58 eV and for the most polar solutions studied (butyronitrile). Our findings demonstrate that exciplexes play a crucial role even in polar solvents and at moderate driving forces, contrary to what is usually assumed. PMID:25243054

  10. Interrupted orthodontic force results in less root resorption than continuous force in human premolars as measured by microcomputed tomography.

    Science.gov (United States)

    Sawicka, Monika; Bedini, Rossella; Wierzbicki, Piotr M; Pameijer, Cornelis H

    2014-01-01

    Root resorption is an undesirable but very frequently occurring sequel of orthodontic treatment. The aim of this study was to compare root resorption caused by either continuous (CF) or interrupted (IF) orthodontic force. The study was performed on human subjects on 30 first upper and lower premolars scheduled for extraction for orthodontic reasons. During four weeks before extraction 12 teeth were subjected to either CF or IF. The force was generated by a segmental titanium-molybdenum alloy cantilever spring that was activated in buccal direction. Initially a force of 60 CentiNewton was used in both CF and IF groups, the force in the former, however, was reactivated every week for 4 weeks. There was no reactivation of force in the IF group after initial application. A morphometric analysis of root resorption was performed by microcomputed tomography and the extent of tooth movement was measured on stone casts. Furthermore, a Tartarate-Resistant Acidic Phosphatase activity (TRAP), the marker enzyme of osteoclasts and cementoclasts, was determined by histochemical method. The Mann-Whitney U test was used to compare the difference in measured parameters between treatment and control tooth groups. The number of resorption craters was significantly higher and their average volume almost twice as large in the CF compared to the IF group (p root structure as opposed to continuous force while the same tooth movement was achieved.

  11. Forced excitation and active control for the measurement of fluid-elastic forces

    International Nuclear Information System (INIS)

    Caillaud, Sebastien

    1999-01-01

    The action of a fluid flow on a tubes bundle is commonly decomposed into a random turbulent excitation and a fluid-elastic excitation. The fluid-elastic forces which are coupled to the tubes movement can be experimentally determined from an analysis of the vibratory response of the structure excited by turbulent forces. For low flow velocities, the turbulent excitation can be insufficient to make the tube significantly vibrate and to permit a correct vibratory analysis. On the opposite side, the structure can become unstable for high flow velocities: the fluid-elastic forces make the fluid-structure damping system fall towards zero. Two experimental methods are proposed in order to extend the considered flow rate. An additional excitation force allows to increase the tube vibration level for improving the signal-noise ratio at low velocities. When the tube is submitted to fluid-elastic instability, an artificial damping contribution by active control allows to stabilize it. Methods are implemented on a flexible tube inserted into rigid tubes bundle water and water-air transverse flows. Two actuator technologies are used: an electromagnetic exciter and piezoelectric actuators. The additional excitation method shows that the fluid-elastic forces remain insignificant at low velocity single phase flow. With the active control method, it is possible to carry out tests beyond the fluid-elastic instability. In two-phase flow, the stabilization of the structure is observed for low vacuum rates. The obtained new results are analyzed with the literature expected results in terms of fluid-elastic coupling and turbulent excitation. (author) [fr

  12. Randomly forced CGL equation stationary measures and the inviscid limit

    CERN Document Server

    Kuksin, S

    2003-01-01

    We study a complex Ginzburg-Landau (CGL) equation perturbed by a random force which is white in time and smooth in the space variable~$x$. Assuming that $\\dim x\\le4$, we prove that this equation has a unique solution and discuss its asymptotic in time properties. Next we consider the case when the random force is proportional to the square root of the viscosity and study the behaviour of stationary solutions as the viscosity goes to zero. We show that, under this limit, a subsequence of solutions in question converges to a nontrivial stationary process formed by global strong solutions of the nonlinear Schr\\"odinger equation.

  13. Towards measurement of the Casimir force between parallel plates separated at sub-mircon distance

    NARCIS (Netherlands)

    Syed Nawazuddin, M.B.; Lammerink, Theodorus S.J.; Wiegerink, Remco J.; Berenschot, Johan W.; de Boer, Meint J.; Elwenspoek, Michael Curt

    2011-01-01

    Ever since its prediction, experimental investigation of the Casimir force has been of great scientific interest. Many research groups have successfully attempted quantifying the force with different device geometries; however measurement of the Casimir force between parallel plates with sub-micron

  14. Measurement of proton capture reactions in the hot cycles: an evaluation of experimental methods

    Energy Technology Data Exchange (ETDEWEB)

    Leleux, P [Inst. de Physique Nucleaire, Univ. Catholique de Louvain, Louvain-la-Neuve (Belgium)

    1998-06-01

    In the hot cycles, most of the proton capture reactions involve radioactive nuclei in the entrance and exit channels. This paper evaluates the specific methods that were designed to measure such reactions. (orig.)

  15. The electrical double layer on gold probed by electrokinetic and surface force measurements

    NARCIS (Netherlands)

    Giesbers, M.; Kleijn, J.M.; Cohen Stuart, M.A.

    2002-01-01

    Gold surfaces, obtained by vacuum deposition of 15-nm gold films on glass and silica wafers, were studied in aqueous solutions by streaming potential measurements and colloidal-probe AFM force measurements. In the force measurements both a bare and a gold-coated silica particle (6 m in diameter)

  16. The big shift: measuring the forces of change

    DEFF Research Database (Denmark)

    Hagel, John; Brown, John Seely; Davison, Lang

    2009-01-01

    Traditional metrics don't capture many of the challenges and opportunities in store for U.S. companies and the national economy. The authors, from Deloitte, present a framework for understanding the forces that have transformed business over the past 40 years--and an index for gauging their impact...

  17. Modelling the effects of the radiation reaction force on the interaction of thin foils with ultra-intense laser fields

    Science.gov (United States)

    Duff, M. J.; Capdessus, R.; Del Sorbo, D.; Ridgers, C. P.; King, M.; McKenna, P.

    2018-06-01

    The effects of the radiation reaction (RR) force on thin foils undergoing radiation pressure acceleration (RPA) are investigated. Using QED-particle-in-cell simulations, the influence of the RR force on the collective electron dynamics within the target can be examined. The magnitude of the RR force is found to be strongly dependent on the target thickness, leading to effects which can be observed on a macroscopic scale, such as changes to the distribution of the emitted radiation and the target dynamics. This suggests that such parameters may be controlled in experiments at multi-PW laser facilities. In addition, the effects of the RR force are characterized in terms of an average radiation emission angle. We present an analytical model which, for the first time, describes the effect of the RR force on the collective electron dynamics within the ‘light-sail’ regime of RPA. The predictions of this model can be tested in future experiments with ultra-high intensity lasers interacting with solid targets.

  18. Quantum limited force measurement in a cavityless optomechanical system

    International Nuclear Information System (INIS)

    Fermani, Rachele; Mancini, Stefano; Tombesi, Paolo

    2004-01-01

    We study the possibility of revealing a weak coherent force by using a pendular mirror as a probe, and coupling this to a radiation field, which acts as the meter, in a cavityless configuration. We determine the sensitivity of such a scheme and show that the use of an entangled meter state greatly improves the ultimate detection limit. We also compare this scheme with that involving an optical cavity

  19. Quantum measurement corrections to CIDNP in photosynthetic reaction centers

    International Nuclear Information System (INIS)

    Kominis, Iannis K

    2013-01-01

    Chemically induced dynamic nuclear polarization is a signature of spin order appearing in many photosynthetic reaction centers. Such polarization, significantly enhanced above thermal equilibrium, is known to result from the nuclear spin sorting inherent in the radical pair mechanism underlying long-lived charge-separated states in photosynthetic reaction centers. We will show here that the recently understood fundamental quantum dynamics of radical-ion-pair reactions open up a new and completely unexpected pathway toward obtaining chemically induced dynamic nuclear polarization signals. The fundamental decoherence mechanism inherent in the recombination process of radical pairs is shown to produce nuclear spin polarizations of the order of 10 4 times (or more) higher than the thermal equilibrium value at the Earth's magnetic field relevant to natural photosynthesis. This opens up the possibility of a fundamentally new exploration of the biological significance of high nuclear polarizations in photosynthesis. (paper)

  20. Vertical Magnetic Levitation Force Measurement on Single Crystal YBaCuO Bulk at Different Temperatures

    Science.gov (United States)

    Celik, Sukru; Guner, Sait Baris; Ozturk, Kemal; Ozturk, Ozgur

    Magnetic levitation force measurements of HTS samples are performed with the use of liquid nitrogen. It is both convenient and cheap. However, the temperature of the sample cannot be changed (77 K) and there is problem of frost. So, it is necessary to build another type of system to measure the levitation force high Tc superconductor at different temperatures. In this study, we fabricated YBaCuO superconducting by top-seeding-melting-growth (TSMG) technique and measured vertical forces of them at FC (Field Cooling) and ZFC (Zero Field Cooling) regimes by using our new designed magnetic levitation force measurement system. It was used to investigate the three-dimensional levitation force and lateral force in the levitation system consisting of a cylindrical magnet and a permanent cylindrical superconductor at different temperatures (37, 47, 57, 67 and 77 K).

  1. Magnetic Levitation Force Measurement System at Any Low Temperatures From 20 K To 300 K

    Science.gov (United States)

    Celik, Sukru; Guner, S. Baris; Coskun, Elvan

    2015-03-01

    Most of the magnetic levitation force measurements in previous studies were performed at liquid nitrogen temperatures. For the levitation force of MgB2 and iron based superconducting samples, magnetic levitation force measurement system is needed. In this study, magnetic levitation force measurement system was designed. In this system, beside vertical force versus vertical motion, lateral and vertical force versus lateral motion measurements, the vertical force versus temperature at the fixed distance between permanent magnet PM - superconducting sample SS and the vertical force versus time measurements were performed at any temperatures from 20 K to 300 K. Thanks to these measurements, the temperature dependence, time dependence, and the distance (magnetic field) and temperature dependences of SS can be investigated. On the other hand, the magnetic stiffness MS measurements can be performed in this system. Using the measurement of MS at different temperature in the range, MS dependence on temperature can be investigated. These measurements at any temperatures in the range help to the superconductivity properties to be characterized. This work was supported by TUBTAK-the Scientific and technological research council of Turkey under project of MFAG - 110T622. This system was applied to the Turkish patent institute with the Application Number of 2013/13638 on 22/11/2013.

  2. Critical Steps in Data Analysis for Precision Casimir Force Measurements with Semiconducting Films

    Science.gov (United States)

    Banishev, A. A.; Chang, Chia-Cheng; Mohideen, U.

    2011-06-01

    Some experimental procedures and corresponding results of the precision measurement of the Casimir force between low doped Indium Tin Oxide (ITO) film and gold sphere are described. Measurements were performed using an Atomic Force Microscope in high vacuum. It is shown that the magnitude of the Casimir force decreases after prolonged UV treatment of the ITO film. Some critical data analysis steps such as the correction for the mechanical drift of the sphere-plate system and photodiodes are discussed.

  3. Neutron detector for fusion reaction-rate measurements

    International Nuclear Information System (INIS)

    Lerche, R.A.; Phillion, D.W.; Tietbohl, G.L.

    1993-01-01

    We have developed a fast, sensitive neutron detector for recording the fusion reaction-rate history of inertial-confinement fusion (ICF) experiments. The detector is based on the fast rise-time of a commercial plastic scintillator (BC-422) and has a response 7 neutrons

  4. Empirical Force Fields for Mechanistic Studies of Chemical Reactions in Proteins.

    Science.gov (United States)

    Das, A K; Meuwly, M

    2016-01-01

    Following chemical reactions in atomistic detail is one of the most challenging aspects of current computational approaches to chemistry. In this chapter the application of adiabatic reactive MD (ARMD) and its multistate version (MS-ARMD) are discussed. Both methods allow to study bond-breaking and bond-forming processes in chemical and biological processes. Particular emphasis is put on practical aspects for applying the methods to investigate the dynamics of chemical reactions. The chapter closes with an outlook of possible generalizations of the methods discussed. © 2016 Elsevier Inc. All rights reserved.

  5. Students' Understanding on Newton's Third Law in Identifying the Reaction Force in Gravity Interactions

    Science.gov (United States)

    Zhou, Shaona; Zhang, Chunbin; Xiao, Hua

    2015-01-01

    In the past three decades, previous researches showed that students had various misconceptions of Newton's Third Law. The present study focused on students' difficulties in identifying the third-law force pair in gravity interaction situations. An instrument involving contexts with gravity and non-gravity associated interactions was designed and…

  6. Prediction of ground reaction forces and moments during various activities of daily living

    NARCIS (Netherlands)

    Fluit, René; Andersen, M.S.; Kolk, S.; Verdonschot, Nicolaas Jacobus Joseph; Koopman, Hubertus F.J.M.

    2014-01-01

    Inverse dynamics based simulations on musculoskeletal models is a commonly used method for the analysis of human movement. Due to inaccuracies in the kinematic and force plate data, and a mismatch between the model and the subject, the equations of motion are violated when solving the inverse

  7. Oxytocin decreases handgrip force in reaction to infant crying in females without harsh parenting experiences

    NARCIS (Netherlands)

    Bakermans-Kranenburg, M.J.; van IJzendoorn, M.H.; Riem, M.M.E.; Tops, M.; Alink, L.R.A.

    2012-01-01

    Infant crying can elicit sensitive caregiving as well as hostility and harsh parenting responses. In the current study (N=42 females) with a double-blind experimental design, we tested the effect of intranasal oxytocin administration on the use of excessive force using a hand-grip dynamometer during

  8. Systems Concepts for Integrated Air Defense of Multinational Mobile Crisis Reaction Forces (Concepts de systemes pour la defense aerienne integree de forces internationales mobiles d'intervention en situation de crise)

    National Research Council Canada - National Science Library

    2001-01-01

    The meeting proceedings from this symposium on System Concepts for Integrated Air Defense of Multinational Mobile Crisis Reaction Forces was organized and sponsored by the Systems Concepts and Integration (SCI...

  9. Force sensor for measuring power transfer between the human body and the environment

    NARCIS (Netherlands)

    Brookhuis, Robert Anton; Lammerink, Theodorus S.J.; Wiegerink, Remco J.; de Boer, Meint J.; Elwenspoek, Michael Curt

    2011-01-01

    A force sensor with capacitive readout is designed and realized for the measurement of mechanical power transfer. The ultimate aim is to integrate this in a glove that determines the complete mechanical interaction between the human hand and the environment. The sensor measures the normal force and

  10. Interface bonding in silicon oxide nanocontacts: interaction potentials and force measurements

    Science.gov (United States)

    Wierez-Kien, M.; Craciun, A. D.; Pinon, A. V.; Le Roux, S.; Gallani, J. L.; Rastei, M. V.

    2018-04-01

    The interface bonding between two silicon-oxide nanoscale surfaces has been studied as a function of atomic nature and size of contacting asperities. The binding forces obtained using various interaction potentials are compared with experimental force curves measured in vacuum with an atomic force microscope. In the limit of small nanocontacts (typically contact area which is altered by stretching speeds. The mean unbinding force is found to decrease as the contact spends time in the attractive regime. This contact weakening is featured by a negative aging coefficient which broadens and shifts the thermal-induced force distribution at low stretching speeds.

  11. Measurement and characterization of lift forces on drops and bubbles in microchannels

    Science.gov (United States)

    Stan, Claudiu; Guglielmini, Laura; Ellerbee, Audrey; Caviezel, Daniel; Whitesides, George; Stone, Howard

    2013-11-01

    The transverse motion of drops and bubbles within liquids flowing in pipes and channels is determined by the combination of several types of hydrodynamic lift forces with external forces. In microfluidic channels, lift forces have been used to position and sort particles with high efficiency and high accuracy. We measured lift forces on drops and bubbles and discriminated between different lift mechanisms under conditions characterized by low particle capillary numbers (0.0003 bubbles. We will present new experimental data that supports a dynamic interfacial mechanism for the second type of lift force, and discuss possible avenues for creating an analytical model for it.

  12. Force Measurement Services at Kebs: AN Overview of Equipment, Procedures and Uncertainty

    Science.gov (United States)

    Bangi, J. O.; Maranga, S. M.; Nganga, S. P.; Mutuli, S. M.

    This paper describes the facilities, instrumentation and procedures currently used in the force laboratory at the Kenya Bureau of Standards (KEBS) for force measurement services. The laboratory uses the Force Calibration Machine (FCM) to calibrate force-measuring instruments. The FCM derives its traceability via comparisons using reference transfer force transducers calibrated by the Force Standard Machines (FSM) of a National Metrology Institute (NMI). The force laboratory is accredited to ISO/IEC 17025 by the Germany Accreditation Body (DAkkS). The accredited measurement scope of the laboratory is 1 MN to calibrate force transducers in both compression and tension modes. ISO 376 procedures are used while calibrating force transducers. The KEBS reference transfer standards have capacities of 10, 50, 300 and 1000 kN to cover the full range of the FCM. The uncertainty in the forces measured by the FCM were reviewed and determined in accordance to the new EURAMET calibration guide. The relative expanded uncertainty of force W realized by FCM was evaluated in a range from 10 kN-1 MN, and was found to be 5.0 × 10-4 with the coverage factor k being equal to 2. The overall normalized error (En) of the comparison results was also found to be less than 1. The accredited Calibration and Measurement Capability (CMC) of the KEBS force laboratory was based on the results of those intercomparisons. The FCM enables KEBS to provide traceability for the calibration of class ‘1’ force instruments as per the ISO 376.

  13. Fiber Bragg grating sensor for simultaneous measurement of temperature and force using polymer open loop

    Science.gov (United States)

    Huang, Yonglin; Zhang, Shiyan

    2014-07-01

    A fiber Bragg grating (FBG) sensor for simultaneous measurement of temperature and force is proposed and demonstrated. Where a part of uniform FBG (about one half length of an FBG) is attached on the polymer open loop, the FBG is divided into two parts which has an equal length. So the two parts can be regarded as two FBGs. Because of the difference of the Young's modulus and the thermal expansion coefficients for two parts of the FBG, the two Bragg reflection wavelengths are shift when the temperature and force are applied on the sensor. Simultaneous measurement of temperature and force is demonstrated experimentally. The experimental results show that the linear response to temperature and force are achieved. The value of applied temperature and force can be obtained from the two Bragg wavelength shift via the coefficient matrix. This study provides a simple and economical method to measure temperature and force simultaneously.

  14. Measurement of cell adhesion force by vertical forcible detachment using an arrowhead nanoneedle and atomic force microscopy

    International Nuclear Information System (INIS)

    Ryu, Seunghwan; Hashizume, Yui; Mishima, Mari; Kawamura, Ryuzo; Tamura, Masato; Matsui, Hirofumi; Matsusaki, Michiya; Akashi, Mitsuru; Nakamura, Chikashi

    2014-01-01

    Graphical abstract: - Highlights: • We developed a method to measure cell adhesion force by detaching cell using an arrowhead nanoneedle and AFM. • A nanofilm consisting of fibronectin and gelatin was formed on cell surface to reinforce the cell cortex. • By the nanofilm lamination, detachment efficiencies of strongly adherent cell lines were improved markedly. - Abstract: The properties of substrates and extracellular matrices (ECM) are important factors governing the functions and fates of mammalian adherent cells. For example, substrate stiffness often affects cell differentiation. At focal adhesions, clustered–integrin bindings link cells mechanically to the ECM. In order to quantitate the affinity between cell and substrate, the cell adhesion force must be measured for single cells. In this study, forcible detachment of a single cell in the vertical direction using AFM was carried out, allowing breakage of the integrin–substrate bindings. An AFM tip was fabricated into an arrowhead shape to detach the cell from the substrate. Peak force observed in the recorded force curve during probe retraction was defined as the adhesion force, and was analyzed for various types of cells. Some of the cell types adhered so strongly that they could not be picked up because of plasma membrane breakage by the arrowhead probe. To address this problem, a technique to reinforce the cellular membrane with layer-by-layer nanofilms composed of fibronectin and gelatin helped to improve insertion efficiency and to prevent cell membrane rupture during the detachment process, allowing successful detachment of the cells. This method for detaching cells, involving cellular membrane reinforcement, may be beneficial for evaluating true cell adhesion forces in various cell types

  15. Utility of spectral measurements of secondary reaction products

    International Nuclear Information System (INIS)

    Heidbrink, W.E.

    1986-02-01

    The spectra of 15 MeV protons and 14 MeV neutrons produced in the burnup of 0.8 MeV 3 He ions and 1 MeV tritons through the d( 3 He,p)α and d(t,n)α fusion reactions contain information on the velocity distributions of the energetic 3 He ions and tritons. 11 refs., 2 figs

  16. Method to measure the force to pull and to break pin bones of fish.

    Science.gov (United States)

    Balaban, Murat O; Jie, Hubert; Yin Yee, Yin; Alçiçek, Zayde

    2015-02-01

    A texture measurement device was modified to measure the force required to pull pin bones from King salmon (Oncorhynchus tshawytscha), snapper (Pagrus auratus), and kahawai (Arripis trutta). Pulled bones were also subjected to tension to measure the breaking force. For all fish, the pulling force depended on the size of the fish, and on the length of the pin bone (P bones. For example, fresh small salmon (about 1500 g whole) required 600 g on average to pull pin bones, and large fish (about 3700 g whole) required 850 g. Longer bones required greater pulling force. The breaking force followed the same trend. In general, the breaking force was greater than the pulling force. This allows the removal of the bones without breaking them. There was no statistically significant (P > 0.05) difference between the forces (both pulling and breaking) from fresh and frozen/thawed samples, although in general frozen/thawed samples required less force to pull. With the quantification of pulling and breaking forces for pin bones, it is possible to design and build better, "more intelligent" pin bone removal equipment. © 2015 Institute of Food Technologists®

  17. A simple mechanism for measuring and adjusting distraction forces during maxillary advancement.

    Science.gov (United States)

    Suzuki, Eduardo Yugo; Suzuki, Boonsiva

    2009-10-01

    Direct measurement of distraction forces on the craniofacial skeleton has never been reported. The present report describes the development of a method of assessing and adjusting traction forces applied through maxillary distraction osteogenesis. A simple mechanism to measure and adjust tension force during maxillary distraction osteogenesis was developed and connected bilaterally to the traction screws of a rigid external distraction device. Measurements were carried out before and after activation using a Shimpo (Nidec-Shimpo America Corporation, Itasca, IL) force gauge in 4 patients (2 with unilateral cleft lip and/or palate, 1 with bilateral cleft lip and palate, and 1 with noncleft) during the distraction process. Activation was performed twice a day at a rate of 1 mm/day. The average maximum force applied throughout the distraction period was 42.5 N (range 16.4 to 65.3 N), with increments, after activation, averaging 10.5 N (range 7.9 to 15.7 N). In patients with unilateral cleft lip and/or palate, distraction forces on the larger segment were 65.1% higher than on the lesser segment. A differential pattern of forces was also observed in the patients with asymmetric noncleft. However, the differential forces between lateral segments were not observed in the patient with bilateral cleft lip and palate. During the activation period, distraction forces progressively increased, whereas the amount of maxillary movement decreased. Pain and discomfort were reported with high forces. Through this mechanism, direct measurement and adjustment of distraction forces during maxillary advancement was possible. The unbalanced pattern of forces observed in patients with cleft suggests the necessity of individual adjustments for controlling pain and clinical symptoms. Accordingly, assessment of distraction forces during maxillary distraction osteogenesis is extremely helpful in understanding the biomechanics of the distraction process.

  18. Joint torques and joint reaction forces during squatting with a forward or backward inclined Smith machine.

    Science.gov (United States)

    Biscarini, Andrea; Botti, Fabio M; Pettorossi, Vito E

    2013-02-01

    We developed a biomechanical model to determine the joint torques and loadings during squatting with a backward/forward-inclined Smith machine. The Smith squat allows a large variety of body positioning (trunk tilt, foot placement, combinations of joint angles) and easy control of weight distribution between forefoot and heel. These distinctive aspects of the exercise can be managed concurrently with the equipment inclination selected to unload specific joint structures while activating specific muscle groups. A backward (forward) equipment inclination decreases (increases) knee torque, and compressive tibiofemoral and patellofemoral forces, while enhances (depresses) hip and lumbosacral torques. For small knee flexion angles, the strain-force on the posterior cruciate ligament increases (decreases) with a backward (forward) equipment inclination, whereas for large knee flexion angles, this behavior is reversed. In the 0 to 60 degree range of knee flexion angles, loads on both cruciate ligaments may be simultaneously suppressed by a 30 degree backward equipment inclination and selecting, for each value of the knee angle, specific pairs of ankle and hip angles. The anterior cruciate ligament is safely maintained unloaded by squatting with backward equipment inclination and uniform/forward foot weight distribution. The conditions for the development of anterior cruciate ligament strain forces are clearly explained.

  19. Measuring the elasticity of plant cells with atomic force microscopy.

    Science.gov (United States)

    Braybrook, Siobhan A

    2015-01-01

    The physical properties of biological materials impact their functions. This is most evident in plants where the cell wall contains each cell's contents and connects each cell to its neighbors irreversibly. Examining the physical properties of the plant cell wall is key to understanding how plant cells, tissues, and organs grow and gain the shapes important for their respective functions. Here, we present an atomic force microscopy-based nanoindentation method for examining the elasticity of plant cells at the subcellular, cellular, and tissue level. We describe the important areas of experimental design to be considered when planning and executing these types of experiments and provide example data as illustration. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. AFM measurements of adhesive forces between carbonaceous particles and the substrates

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Tianqi [Institute of Nuclear and New Energy Technology of Tsinghua University, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Beijing 100084 (China); Peng, Wei, E-mail: pengwei@tsinghua.edu.cn [Institute of Nuclear and New Energy Technology of Tsinghua University, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Beijing 100084 (China); Shen, Ke [Institute of Nuclear and New Energy Technology of Tsinghua University, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Beijing 100084 (China); Yu, Suyuan, E-mail: suyuan@tsinghua.edu.cn [Center for Combustion Energy, Key Laboratory for Thermal Science and Power Engineering of Ministry of Educations, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China)

    2015-11-15

    Highlights: • Adhesive force of spherical carbonaceous particle MCMBs and HTR-10 graphite matrix debris were measured for the first time. • The measured equivalent works of adhesion were much smaller than the ideal values. • The shape factor and the particle morphology reduce the adhesive force. • The adhesion effect does not change directly with the asperity size. - Abstract: Graphite dust is carbonaceous particles generated during operation of High Temperature Gas-Cooled Reactors (HTR). Graphite dust resuspension is the key behavior associated with HTR source term analyses and environmental safety assessment. The adhesive force is the key factor that determines the resuspension rate. The present study used an atomic force microscope (AFM) to measure the adhesive force between a single carbonaceous particle and the substrate. The measurements were performed on mica, graphite IG110 and Inconel 800H. The prepared “probe cantilevers” were mesocarbon microbeads (MCMB), fuel element debris from HTR-10 and graphite NBG18. The equivalent work of adhesion was derived from the measured adhesive force and calculated based on substrate profile approximation and the JKR theoretical model. The measured work was smaller than the ideal work of adhesion, most likely due to the rough particle morphology and the rough substrate surface. Additionally, a shape factor imposes a constraint on the lateral deformation of the particles. Furthermore, surface roughness could reduce the adhesive force some depending on the particle size. Once the particle was too small to be trapped into a trough, the adhesive force would not be further reduced.

  1. AFM measurements of adhesive forces between carbonaceous particles and the substrates

    International Nuclear Information System (INIS)

    Zhang, Tianqi; Peng, Wei; Shen, Ke; Yu, Suyuan

    2015-01-01

    Highlights: • Adhesive force of spherical carbonaceous particle MCMBs and HTR-10 graphite matrix debris were measured for the first time. • The measured equivalent works of adhesion were much smaller than the ideal values. • The shape factor and the particle morphology reduce the adhesive force. • The adhesion effect does not change directly with the asperity size. - Abstract: Graphite dust is carbonaceous particles generated during operation of High Temperature Gas-Cooled Reactors (HTR). Graphite dust resuspension is the key behavior associated with HTR source term analyses and environmental safety assessment. The adhesive force is the key factor that determines the resuspension rate. The present study used an atomic force microscope (AFM) to measure the adhesive force between a single carbonaceous particle and the substrate. The measurements were performed on mica, graphite IG110 and Inconel 800H. The prepared “probe cantilevers” were mesocarbon microbeads (MCMB), fuel element debris from HTR-10 and graphite NBG18. The equivalent work of adhesion was derived from the measured adhesive force and calculated based on substrate profile approximation and the JKR theoretical model. The measured work was smaller than the ideal work of adhesion, most likely due to the rough particle morphology and the rough substrate surface. Additionally, a shape factor imposes a constraint on the lateral deformation of the particles. Furthermore, surface roughness could reduce the adhesive force some depending on the particle size. Once the particle was too small to be trapped into a trough, the adhesive force would not be further reduced.

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

    Science.gov (United States)

    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.

  3. Reaction

    African Journals Online (AJOL)

    abp

    19 oct. 2017 ... Reaction to Mohamed Said Nakhli et al. concerning the article: "When the axillary block remains the only alternative in a 5 year old child". .... Bertini L1, Savoia G, De Nicola A, Ivani G, Gravino E, Albani A et al ... 2010;7(2):101-.

  4. Comparisons of Force Measurement Methods for DBD Plasma Actuators in Quiescent Air

    Science.gov (United States)

    Hoskinson, Alan R.; Hershkowitz, Noah; Ashpis, David E.

    2009-01-01

    We have performed measurements of the force induced by both single (one electrode insulated) and double (both electrodes insulated) dielectric barrier discharge plasma actuators in quiescent air. We have shown that, for single barrier actuators with cylindrical exposed electrodes, as the electrode diameter decrease the force efficiencies increase much faster than a previously reported linear trend. This behavior has been experimentally verified using two different measurement techniques: stagnation probe measurements of the induced flow velocity and direct measurement of the force using an electronic balance. Actuators with rectangular cross-section exposed electrodes do not show the same rapid increase at small thicknesses. We have also shown that the induced force is independent of the material used for the exposed electrode. The same techniques have shown that the induced force of a double barrier actuator increases with decreasing narrow electrode diameter.

  5. Experiment to measure the gravitational force on the antiproton

    International Nuclear Information System (INIS)

    Brown, R.E.

    1985-01-01

    A collaboration has been formed to measure the acceleration of antiprotons in the earth's gravitational field. The technique is to produce, decelerate, and trap quantities of antiprotons, to cool them to untralow energy, and to measure their acceleration in a time-of-flight experiment. Present plans and the results of initial efforts toward this end are presented

  6. Exclusive measurements of nuclear breakup reactions of 17Ne

    International Nuclear Information System (INIS)

    Wamers, F.; Marganiec, J.; Aksouh, F.; Aksyutina, Y.; Boretzky, K.; Chatillon, A.; Emling, H.; Geissel, H.; Heil, M.; Hoffmann, J.; Karagiannis, C.; Kiselev, O.A.; Kurz, N.; Larsson, K.; Litvinov, Y.A.; Nociforo, C.; Ott, W.; Simon, H.; Suemmerer, K.; Weick, H.; Alvarez-Pol, H.; Beceiro-Novo, S.; Cortina-Gil, D.; Rodriguez-Tajes, C.; Aumann, T.; Panin, V.; Bertulani, C.A.; Borge, M.J.G.; Galaviz, D.; Perea, A.; Tengblad, O.; Chartier, M.; Taylor, J.; Chulkov, L.V.; Egorova, I.A.; Ershova, O.; Langer, C.; Plag, R.; Reifarth, R.; Wimmer, C.; Forssen, C.; Johansson, H.; Jonson, B.; Nilsson, T.; Nyman, G.; Tengborn, E.; Zhukov, M.V.; Fraile, L.M.; Fynbo, H.; Riisager, K.; Grigorenko, L.V.; Hoffmann, D.H.; Richter, A.; Schrieder, G.; Karakoc, M.; Kratz, J.V.; Kulessa, R.; Lantz, M.; Le Bleis, T.; Lemmon, R.; Mahata, K.; Muentz, C.; Stroth, J.; Parfenova, Y.L.; Paschalis, S.; Rossi, D.; Savran, D.; Shul'gina, N.B.

    2014-01-01

    We have studied one-proton-removal reactions of about 500 MeV/u 17 Ne beams on a carbon target at the R 3 B/LAND setup at GSI by detecting beam-like 15 O-p and determining their relative-energy distribution. We exclusively selected the removal of a 17 Ne halo proton, and the Glauber-model analysis of the 16 F momentum distribution resulted in an s 2 contribution in the 17 Ne ground state of about 40 %. (authors)

  7. Upper atmosphere research: Reaction rate and optical measurements

    Science.gov (United States)

    Stief, L. J.; Allen, J. E., Jr.; Nava, D. F.; Payne, W. A., Jr.

    1990-01-01

    The objective is to provide photochemical, kinetic, and spectroscopic information necessary for photochemical models of the Earth's upper atmosphere and to examine reactions or reactants not presently in the models to either confirm the correctness of their exclusion or provide evidence to justify future inclusion in the models. New initiatives are being taken in technique development (many of them laser based) and in the application of established techniques to address gaps in the photochemical/kinetic data base, as well as to provide increasingly reliable information.

  8. Hydrogen release from irradiated elastomers measured by Nuclear Reaction Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Jagielski, J., E-mail: jacek.jagielski@itme.edu.pl [Institute for Electronic Materials Technology, Wolczynska 133, 01-926 Warszawa (Poland); National Centre for Nuclear Research, A. Soltana 7, 05-400 Swierk/Otwock (Poland); Ostaszewska, U. [Institute for Engineering of Polymer Materials & Dyes, Division of Elastomers & Rubber Technology, Harcerska 30, 05-820 Piastow (Poland); Bielinski, D.M. [Technical University of Lodz, Institute of Polymer & Dye Technology, Stefanowskiego 12/16, 90-924 Lodz (Poland); Grambole, D. [Institute of Ion Beam Physics and Materials Research, Helmholtz Zentrum Dresden Rossendorf, PO Box 51 01 19, D-01314 Dresden (Germany); Romaniec, M.; Jozwik, I.; Kozinski, R. [Institute for Electronic Materials Technology, Wolczynska 133, 01-926 Warszawa (Poland); Kosinska, A. [National Centre for Nuclear Research, A. Soltana 7, 05-400 Swierk/Otwock (Poland)

    2016-03-15

    Ion irradiation appears as an interesting method of modification of elastomers, especially friction and wear properties. Main structural effect caused by heavy ions is a massive loss of hydrogen from the surface layer leading to its smoothening and shrinking. The paper presents the results of hydrogen release from various elastomers upon irradiation with H{sup +}, He{sup +} and Ar{sup +} studied by using Nuclear Reaction Analysis (NRA) method. The analysis of the experimental data indicates that the hydrogen release is controlled by inelastic collisions between ions and target electrons. The last part of the study was focused on preliminary analysis of mechanical properties of irradiated rubbers.

  9. Solvent effect on the degree of (a)synchronicity in polar Diels-Alder reactions from the perspective of the reaction force constant analysis.

    Science.gov (United States)

    Yepes, Diana; Martínez-Araya, Jorge I; Jaque, Pablo

    2017-12-29

    In this work, we computationally evaluated the influence of six different molecular solvents, described as a polarizable continuum model at the M06-2X/6-31+G(d,p) level, on the activation barrier/reaction rate, overall energy change, TS geometry, and degree of (a)synchronicity of two concerted Diels-Alder cycloadditions of acrolein (R1) and its complex with Lewis acid acrolein···BH 3 (R2) to cyclopentadiene. In gas-phase, we found that both exothermicity and activation barrier are only reduced by about 2.0 kcal mol -1 , and the asynchronicity character of the mechanism is accentuated when BH 3 is included. An increment in the solvent's polarity lowers the activation energy of R1 by 1.3 kcal mol -1 , while for R2 the reaction rate is enhanced by more than 2000 times at room temperature (i.e., the activation energy decreases by 4.5 kcal mol -1 ) if the highest polar media is employed. Therefore, a synergistic effect is achieved when both external agents, i.e., Lewis acid catalyst and polar solvent, are included together. This effect was ascribed to the ability of the solvent to favor the encounter between cyclopentadiene and acrolein···BH 3 . This was validated by the asymmetry of the TS which becomes highly pronounced when either both or just BH 3 is considered or the solvent's polarity is increased. Finally, the reaction force constant κ(ξ) reveals that an increment in the solvent's polarity is able to turn a moderate asynchronous mechanism of the formation of the new C-C σ-bonds into a highly asynchronous one. Graphical abstract A synergistic effect is achieved when both external agents, i.e., Lewis acid catalyst and polar solvent, are included together: lowered energy barriers and increased asynchronicities.

  10. Precision measurement of the Casimir-Lifshitz force in a fluid

    International Nuclear Information System (INIS)

    Munday, J. N.; Capasso, Federico

    2007-01-01

    The Casimir force, which results from the confinement of the quantum-mechanical zero-point fluctuations of electromagnetic fields, has received significant attention in recent years for its effect on micro- and nanoscale mechanical systems. With few exceptions, experimental observations have been limited to interacting conductive bodies separated by vacuum or air. However, interesting phenomena, including repulsive forces, are expected to exist in certain circumstances between metals and dielectrics when the intervening medium is not vacuum. In order to better understand the effect of the Casimir force in such situations and to test the robustness of the generalized Casimir-Lifshitz theory, we have performed precision measurements of the Casimir force between two metals immersed in a fluid. For this situation, the measured force is attractive and is approximately 80% smaller than the force predicted by Casimir for ideal metals in vacuum. We present experimental results and find them to be consistent with Lifshitz's theory

  11. Using optical tweezers for measuring the interaction forces between human bone cells and implant surfaces: System design and force calibration

    International Nuclear Information System (INIS)

    Andersson, Martin; Madgavkar, Ashwin; Stjerndahl, Maria; Wu, Yanrong; Tan, Weihong; Duran, Randy; Niehren, Stefan; Mustafa, Kamal; Arvidson, Kristina; Wennerberg, Ann

    2007-01-01

    Optical tweezers were used to study the interaction and attachment of human bone cells to various types of medical implant materials. Ideally, the implant should facilitate cell attachment and promote migration of the progenitor cells in order to decrease the healing time. It is therefore of interest, in a controlled manner, to be able to monitor the cell adhesion process. Results from such studies would help foresee the clinical outcome of integrating medical implants. The interactions between two primary cell culture models, human gingival fibroblasts and bone forming human osteoblast cells, and three different implant materials, glass, titanium, and hydroxyapatite, were studied. A novel type of optical tweezers, which has a newly designed quadrant detector and a powerful 3 W laser was constructed and force calibrated using two different methods: one method in which the stiffness of the optical trap was obtained by monitoring the phase lag between the trap and the moved object when imposing a forced oscillation on the trapped object and another method in which the maximum trapping force was derived from the critical velocity at which the object escapes the trap. Polystyrene beads as well as cells were utilized for the calibrations. This is the first time that cells have been used directly for these types of force calibrations and, hence, direct measurements of forces exerted on cells can be performed, thus avoiding the difficulties often encountered when translating the results obtained from cell measurements to the calibrations obtained with reference materials. This more straightforward approach represents an advantage in comparison to established methods

  12. The evolution of vertical climbing in primates: evidence from reaction forces.

    Science.gov (United States)

    Hanna, Jandy B; Granatosky, Michael C; Rana, Pooja; Schmitt, Daniel

    2017-09-01

    Vertical climbing is an essential behavior for arboreal animals, yet limb mechanics during climbing are poorly understood and rarely compared with those observed during horizontal walking. Primates commonly engage in both arboreal walking and vertical climbing, and this makes them an ideal taxa in which to compare these locomotor forms. Additionally, primates exhibit unusual limb mechanics compared with most other quadrupeds, with weight distribution biased towards the hindlimbs, a pattern that is argued to have evolved in response to the challenges of arboreal walking. Here we test an alternative hypothesis that functional differentiation between the limbs evolved initially as a response to climbing. Eight primate species were recorded locomoting on instrumented vertical and horizontal simulated arboreal runways. Forces along the axis of, and normal to, the support were recorded. During walking, all primates displayed forelimbs that were net braking, and hindlimbs that were net propulsive. In contrast, both limbs served a propulsive role during climbing. In all species, except the lorisids, the hindlimbs produced greater propulsive forces than the forelimbs during climbing. During climbing, the hindlimbs tends to support compressive loads, while the forelimb forces tend to be primarily tensile. This functional disparity appears to be body-size dependent. The tensile loading of the forelimbs versus the compressive loading of the hindlimbs observed during climbing may have important evolutionary implications for primates, and it may be the case that hindlimb-biased weight support exhibited during quadrupedal walking in primates may be derived from their basal condition of climbing thin branches. © 2017. Published by The Company of Biologists Ltd.

  13. an extended octagonal ring dynamometer for measurement of forces

    African Journals Online (AJOL)

    NIJOTECH

    The analysis, design, construction, evaluation and use of an extended octagonal ring dynamometer for ... For tillage applications, it has been used ..... confirmed that the dynamometer and the measurement system were capable of indicating.

  14. Finger-Shaped GelForce: Sensor for Measuring Surface Traction Fields for Robotic Hand.

    Science.gov (United States)

    Sato, K; Kamiyama, K; Kawakami, N; Tachi, S

    2010-01-01

    It is believed that the use of haptic sensors to measure the magnitude, direction, and distribution of a force will enable a robotic hand to perform dexterous operations. Therefore, we develop a new type of finger-shaped haptic sensor using GelForce technology. GelForce is a vision-based sensor that can be used to measure the distribution of force vectors, or surface traction fields. The simple structure of the GelForce enables us to develop a compact finger-shaped GelForce for the robotic hand. GelForce that is developed on the basis of an elastic theory can be used to calculate surface traction fields using a conversion equation. However, this conversion equation cannot be analytically solved when the elastic body of the sensor has a complicated shape such as the shape of a finger. Therefore, we propose an observational method and construct a prototype of the finger-shaped GelForce. By using this prototype, we evaluate the basic performance of the finger-shaped GelForce. Then, we conduct a field test by performing grasping operations using a robotic hand. The results of this test show that using the observational method, the finger-shaped GelForce can be successfully used in a robotic hand.

  15. Measurements of dispersion forces between colloidal latex particles with the atomic force microscope and comparison with Lifshitz theory

    Energy Technology Data Exchange (ETDEWEB)

    Elzbieciak-Wodka, Magdalena; Ruiz-Cabello, F. Javier Montes; Trefalt, Gregor; Maroni, Plinio; Borkovec, Michal, E-mail: michal.borkovec@unige.ch [Department of Inorganic and Analytical Chemistry, University of Geneva, Sciences II, 30, Quai Ernest-Ansermet, 1205 Geneva (Switzerland); Popescu, Mihail N. [Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095 (Australia)

    2014-03-14

    Interaction forces between carboxylate colloidal latex particles of about 2 μm in diameter immersed in aqueous solutions of monovalent salts were measured with the colloidal probe technique, which is based on the atomic force microscope. We have systematically varied the ionic strength, the type of salt, and also the surface charge densities of the particles through changes in the solution pH. Based on these measurements, we have accurately measured the dispersion forces acting between the particles and estimated the apparent Hamaker constant to be (2.0 ± 0.5) × 10{sup −21} J at a separation distance of about 10 nm. This value is basically independent of the salt concentration and the type of salt. Good agreement with Lifshitz theory is found when roughness effects are taken into account. The combination of retardation and roughness effects reduces the value of the apparent Hamaker constant and its ionic strength dependence with respect to the case of ideally smooth surfaces.

  16. A Modernized UDM-600 Dynamometer-Based Setup for the Cutting Force Measurement

    Directory of Open Access Journals (Sweden)

    Ya. I. Shuliak

    2016-01-01

    Full Text Available The article considers development of a modernized UDM-600 dynamometer-based setup for measuring the cutting force components. Modernization of existing equipment to improve the method of recording the cutting force components in the automated mode is of relevance. The measuring setup allows recording the cutting force components in turning and milling, as well as the axial force and the torque in the drilling and milling operations.The article presents a block diagram and a schematic diagram of the setup to measure the cutting force components, and describes a basic principle of measuring units within the modernized setup. The developed setup uses a half-bridge strain gauge measuring circuit to record the cutting forces. To enhance the measuring circuit output voltage is used a 16-channel amplifier of LA-UN16 model with a discretely adjustable gain. To record and process electrical signals is used a data acquisition device of NI USB-6009 model, which enables transmitting the received data to a PC via USB-interface. The data acquisition device has a built-in stabilized DC power supply that is used to power the strain gauge bridges. A developed schematic diagram of the measuring setup allows us to realize this measuring device and implement its modernization.Final processing of recorded data is provided through the software developed in visual programming environment LabVIEW 9.0. The program allows us to show the real-time measuring values of the cutting force components graphically and to record the taken data to a text file.The measuring setup modernization enabled increasing measurement accuracy and reducing time for processing and analysis of experimental data obtained when measuring the cutting force components. The MT2 Department of BMSTU uses it in education and research activities and in experimental efforts and laboratory classes.

  17. Gait Phases Recognition from Accelerations and Ground Reaction Forces: Application of Neural Networks

    Directory of Open Access Journals (Sweden)

    S. Rafajlović

    2009-06-01

    Full Text Available The goal of this study was to test the applicability of accelerometer as the sensor for assessment of the walking. We present here the comparison of gait phases detected from the data recorded by force sensing resistors mounted in the shoe insoles, non-processed acceleration and processed acceleration perpendicular to the direction of the foot. The gait phases in all three cases were detected by means of a neural network. The output from the neural network was the gait phase, while the inputs were data from the sensors. The results show that the errors were in the ranges: 30 ms (2.7% – force sensors; 150 ms (13.6% – nonprocessed acceleration, and 120 ms (11% – processed acceleration data. This result suggests that it is possible to use the accelerometer as the gait phase detector, however, with the knowledge that the gait phases are time shifted for about 100 ms with respect the neural network predicted times.

  18. Effect of foot orthoses on magnitude and timing of rearfoot and tibial motions, ground reaction force and knee moment during running.

    Science.gov (United States)

    Eslami, Mansour; Begon, Mickaël; Hinse, Sébastien; Sadeghi, Heydar; Popov, Peter; Allard, Paul

    2009-11-01

    Changes in magnitude and timing of rearfoot eversion and tibial internal rotation by foot orthoses and their contributions to vertical ground reaction force and knee joint moments are not well understood. The objectives of this study were to test if orthoses modify the magnitude and time to peak rearfoot eversion, tibial internal rotation, active ground reaction force and knee adduction moment and determine if rearfoot eversion, tibial internal rotation magnitudes are correlated to peak active ground reaction force and knee adduction moment during the first 60% stance phase of running. Eleven healthy men ran at 170 steps per minute in shod and with foot orthoses conditions. Video and force-plate data were collected simultaneously to calculate foot joint angular displacement, ground reaction forces and knee adduction moments. Results showed that wearing semi-rigid foot orthoses significantly reduced rearfoot eversion 40% (4.1 degrees ; p=0.001) and peak active ground reaction force 6% (0.96N/kg; p=0.008). No significant time differences occurred among the peak rearfoot eversion, tibial internal rotation and peak active ground reaction force in both conditions. A positive and significant correlation was observed between peak knee adduction moment and the magnitude of rearfoot eversion during shod (r=0.59; p=0.04) and shod/orthoses running (r=0.65; p=0.02). In conclusion, foot orthoses could reduce rearfoot eversion so that this can be associated with a reduction of knee adduction moment during the first 60% stance phase of running. Finding implies that modifying rearfoot and tibial motions during running could not be related to a reduction of the ground reaction force.

  19. Update: Partnership for the Revitalization of National Wind Tunnel Force Measurement Technology Capability

    Science.gov (United States)

    Rhew, Ray D.

    2010-01-01

    NASA's Aeronautics Test Program (ATP) chartered a team to examine the issues and risks associated with the lack of funding and focus on force measurement over the past several years, focusing specifically on strain-gage balances. NASA partnered with the U.S. Air Force's Arnold Engineering Development Center (AEDC) to exploit their combined capabilities and take a national level government view of the problem and established the National Force Measurement Technology Capability (NFMTC) project. This paper provides an update on the team's status for revitalizing the government's balance capability with respect to designing, fabricating, calibrating, and using the these critical measurement devices.

  20. Aspects of scanning force microscope probes and their effects on dimensional measurement

    Energy Technology Data Exchange (ETDEWEB)

    Yacoot, Andrew [National Physical Laboratory, Teddington, Middlesex TW11 0LW (United Kingdom); Koenders, Ludger [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany)], E-mail: andrew.yacoot@npl.co.uk

    2008-05-21

    The review will describe the various scanning probe microscopy tips and cantilevers used today for scanning force microscopy and magnetic force microscopy. Work undertaken to quantify the properties of cantilevers and tips, e.g. shape and radius, is reviewed together with an overview of the various tip-sample interactions that affect dimensional measurements. (topical review)

  1. TOPICAL REVIEW: Aspects of scanning force microscope probes and their effects on dimensional measurement

    Science.gov (United States)

    Yacoot, Andrew; Koenders, Ludger

    2008-05-01

    The review will describe the various scanning probe microscopy tips and cantilevers used today for scanning force microscopy and magnetic force microscopy. Work undertaken to quantify the properties of cantilevers and tips, e.g. shape and radius, is reviewed together with an overview of the various tip-sample interactions that affect dimensional measurements.

  2. Aspects of scanning force microscope probes and their effects on dimensional measurement

    International Nuclear Information System (INIS)

    Yacoot, Andrew; Koenders, Ludger

    2008-01-01

    The review will describe the various scanning probe microscopy tips and cantilevers used today for scanning force microscopy and magnetic force microscopy. Work undertaken to quantify the properties of cantilevers and tips, e.g. shape and radius, is reviewed together with an overview of the various tip-sample interactions that affect dimensional measurements. (topical review)

  3. Time, tire measurements forces and moments: a new standard for steady state cornering tyre testing

    NARCIS (Netherlands)

    Oosten, J.J.M. van; Savi, C.; Augustin, M.; Bouhet, O.; Sommer, J.; Colinot, J.P.

    1999-01-01

    In order to develop vehicles which have maximum active safety, car manufacturers need information about the so-called force and moment properties of tyres. Vehicle manufacturers, tyre suppliers and automotive research organisations have advanced test equipment to measure the forces between a tyre

  4. The application of magnetic force differentiation for the measurement of the affinity of peptide libraries

    International Nuclear Information System (INIS)

    Shang Hao; Kirkham, Perry M.; Myers, Tina M.; Cassell, Gail H.; Lee, Gil U.

    2005-01-01

    A new method has been developed for measuring the binding affinity of phage displayed peptides and a target protein using magnetic particles. The specific interaction between the phage displayed peptides and the target protein was subject to a force generated by the magnetic particle. The binding affinity was obtained by analyzing the force-bond lifetime

  5. Comparative analysis of internal friction and natural frequency measured by free decay and forced vibration

    International Nuclear Information System (INIS)

    Wang, Y. Z.; Ding, X. D.; Xiong, X. M.; Zhang, J. X.

    2007-01-01

    Relations between various values of the internal friction (tgδ, Q -1 , Q -1* , and Λ/π) measured by free decay and forced vibration are analyzed systemically based on a fundamental mechanical model in this paper. Additionally, relations between various natural frequencies, such as vibration frequency of free decay ω FD , displacement-resonant frequency of forced vibration ω d , and velocity-resonant frequency of forced vibration ω 0 are calculated. Moreover, measurement of natural frequencies of a copper specimen of 99.9% purity has been made to demonstrate the relation between the measured natural frequencies of the system by forced vibration and free decay. These results are of importance for not only more accurate measurement of the elastic modulus of materials but also the data conversion between different internal friction measurements

  6. Measurement of two-phase flow momentum with force transducers

    International Nuclear Information System (INIS)

    Hardy, J.E.; Smith, J.E.

    1990-01-01

    Two strain-gage-based drag transducers were developed to measure two-phase flow in simulated pressurized water reactor (PWR) test facilities. One transducer, a drag body (DB), was designed to measure the bidirectional average momentum flux passing through an end box. The second drag sensor, a break through detector (BTD), was designed to sense liquid downflow from the upper plenum to the core region. After prototype sensors passed numerous acceptance tests, transducers were fabricated and installed in two experimental test facilities, one in Japan and one in West Germany. High-quality data were extracted from both the DBs and BTDs for a variety of loss-of-coolant accident (LOCA) scenarios. The information collected from these sensors has added to the understanding of the thermohydraulic phenomena that occur during the refill/reflood stage of a LOCA in a PWR. 9 refs., 15 figs

  7. Measurement of Forces and Moments Transmitted to the Residual Limb

    Science.gov (United States)

    2009-08-01

    alignment of a prosthesis. Walking speed and cadence will be measured during the baseline conditions and a metronome will be used to help subjects...reproduced and you will be allowed to walk with your original alignment briefly to refresh your memory on how it feels. A metronome may be used to...speed and compare the maximum pressures to those in activity A (A metronome will be used to help you establish a cadence that is 10% - 15% faster than

  8. A comparison of ground reaction force components according to the foothold heights in 16-t truck during downward step.

    Science.gov (United States)

    Hyun, Seung-Hyun; Ryew, Che-Cheong

    2017-12-01

    The aim of this study is to compare and analyze the components of ground reaction force (GRF) relative to the foothold heights during downward step of 16-t truck. Adult males (n= 10) jumped downward from each 1st, 2nd, 3rd foothold step and driver's seat orderly using hand rail. Sampling rate of force components of 3 axis (medial-lateral [ML] GRF, anterior-posterior [AP] GRF, peak vertical force [PVF]), variables (COPx, COPy, COP area) of center of pressure (COP), loading rate, and stability index (ML, AP, vertical, and dynamic postural stability index [DPSI]) processed from GRF system was cut off at 1,000 Hz. and variables was processed with repeated one-way analysis of variance. AP GRF, PVF and loading rate showed higher value in case of not used hand rail than that used hand rail in all 1st, 2nd, and 3rd of foothold step. DPSI showed more lowered stability in order of 2nd, 3rd step than 1st foothold step used with hand rail, of which showed lowest stability from driver's seat. COPx, COPy, and COP area showed higher value in case of 2nd and 3rd than that of 1st of foothold step, and showed lowest stability from driver's seat. It is more desirable for cargo truck driver to utilize an available hand rail in order of 3rd, 2nd, and 1st of foothold step than downward stepping directly, thus by which may results in decrease of falling injuries and minimization of impulsive force transferring to muscular-skeletal system.

  9. Measuring the nanomechanical properties of cancer cells by digital pulsed force mode imaging

    International Nuclear Information System (INIS)

    Marti, Othmar; Holzwarth, Michael; Beil, Michael

    2008-01-01

    In this paper, we demonstrate that the digital pulsed force mode data can distinguish two cancer cell lines (HeLa, Panc) by their mechanical properties. The live cells were imaged in buffer solution. The digital pulsed force mode measured 175 force-distance curves per second which, due to the speed of the measurement, were distorted by the viscous drag in the buffer. We show that this drag force causes a sinusoidal addition to the force-distance curves. By subtracting the viscous drag effect one obtains standard force-distance curves. The force-distance curves are then evaluated to extract key data on the curves, such as adhesion energies, local stiffness or the width of the hysteresis loop. These data are then correlated to classify the force-distance curves. We show examples based on the width of the hysteresis loop and the adhesion energies. Outliers in this classification scheme are points where, potentially, interesting new physics or different physics might happen. Based on classification schemes adapted to experimental settings, we propose that the digital pulsed force mode is a tool to evaluate the time evolution of the mechanical response of cells

  10. Measuring the nanomechanical properties of cancer cells by digital pulsed force mode imaging

    Energy Technology Data Exchange (ETDEWEB)

    Marti, Othmar; Holzwarth, Michael [Institute of Experimental Physics, Ulm University, D-89069 Ulm (Germany); Beil, Michael [Department of Internal Medicine, Ulm University, D-89069 Ulm (Germany)], E-mail: othmar.marti@uni-ulm.de, E-mail: michael.holzwarth@uni-ulm.de, E-mail: michael.beil@uni-ulm.de

    2008-09-24

    In this paper, we demonstrate that the digital pulsed force mode data can distinguish two cancer cell lines (HeLa, Panc) by their mechanical properties. The live cells were imaged in buffer solution. The digital pulsed force mode measured 175 force-distance curves per second which, due to the speed of the measurement, were distorted by the viscous drag in the buffer. We show that this drag force causes a sinusoidal addition to the force-distance curves. By subtracting the viscous drag effect one obtains standard force-distance curves. The force-distance curves are then evaluated to extract key data on the curves, such as adhesion energies, local stiffness or the width of the hysteresis loop. These data are then correlated to classify the force-distance curves. We show examples based on the width of the hysteresis loop and the adhesion energies. Outliers in this classification scheme are points where, potentially, interesting new physics or different physics might happen. Based on classification schemes adapted to experimental settings, we propose that the digital pulsed force mode is a tool to evaluate the time evolution of the mechanical response of cells.

  11. Nuclear reactions cross section measurement using Z-pinch technology

    Energy Technology Data Exchange (ETDEWEB)

    Bulgakov, T; Bystritskij, V; Mesyats, G A [Russian Academy of Sciences, Tomsk (Russian Federation). Institute of Electrophysics; and others

    1997-12-31

    Direct experimental estimate of the upper limit of the d + d {yields} {sup 3}He + n cross-section at deuteron energies below the keV region was obtained for the first time. The experiment was performed at the Pulsed Ion Beam Accelerator of the High-Current Electronics Institute in Tomsk, using high intensity, radially converging deuteron beams, generated during implosion of liner plasma. A two-jet liner made of 17% D{sub 2} + 83% N{sub 2} gas was used, with the inner jet serving as the target. The dd-fusion neutrons were registered by time-of-flight scintillator spectrometers and BF{sub 3} detectors of thermal neutrons placed in a polyethylene moderator. The upper limit obtained for the d + d {yields} {sup 3}He + n cross-section for a deuteron energy of 440 eV is {sigma} < 2 x 10{sup -34} cm{sup 2} at the 90% confidence level. The result demonstrates that the liner implosion technique can be used in the investigation of nuclear reactions between light nuclei at infra low energies, previously not accessible in experiments with classical beam accelerators. (author). 7 refs.

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

    Science.gov (United States)

    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.

  13. Thermophoretic forces on DNA measured with a single-molecule spring balance

    DEFF Research Database (Denmark)

    Pedersen, Jonas Nyvold; Lüscher, Christopher James; Marie, Rodolphe

    2014-01-01

    We stretch a single DNA molecule with thermophoretic forces and measure these forces with a spring balance: the DNA molecule itself. It is an entropic spring which we calibrate, using as a benchmark its Brownian motion in the nanochannel that contains and prestretches it. This direct measurement ....... We find the Soret coefficient per unit length of DNA at various ionic strengths. It agrees, with novel precision, with results obtained in bulk for DNA too short to shield itself and with the thermodynamic model of thermophoresis.......We stretch a single DNA molecule with thermophoretic forces and measure these forces with a spring balance: the DNA molecule itself. It is an entropic spring which we calibrate, using as a benchmark its Brownian motion in the nanochannel that contains and prestretches it. This direct measurement...

  14. Measuring Relationships: A Model for Evaluating U.S. Air Force Public Affairs Programs

    National Research Council Canada - National Science Library

    Della Vedova, Joseph P

    2005-01-01

    The thesis advanced here is that Air Force Public Affairs should be responsible for managing the organization-public relationship and that the effectiveness of that management can be measured in terms...

  15. A levitation force and magnetic field distribution measurement system in three dimensions

    International Nuclear Information System (INIS)

    Yang, W.M.; Chao, X.X.; Shu, Z.B.; Zhu, S.H.; Wu, X.L.; Bian, X.B.; Liu, P.

    2006-01-01

    A levitation force and magnetic field distribution measurement system in three dimension has been designed and constructed, which can be used for the levitation force measurement between a superconductor and a magnet, or magnet to magnet in three dimensions; and for the measurement of magnetic field distribution in three dimensions according to your need in space. It can also give out the dynamical changing result of magnetic field density with time during levitation force measurement. If we change the sensor of the detector of the measurement system, it also can be used for other kinds of measurement of physical properties. It is a good device for the measurement of magnetic properties of materials. In addition the device can also be used to work at carving in three dimensions

  16. Measurements of rates of some reactions related to radiolytic effect on aqueous iodide solution

    International Nuclear Information System (INIS)

    Shiraishi, H.; Okuda, H.; Ishigure, K.

    1986-01-01

    A number of reactions takes place concurrently when aqueous iodide solution is subjected to radiation field. In order to help analyze this complicated radiation effect measurements of rate constants were undertaken for several important reactions. One of these concerns reduction of hypoiodous acid by hydrogen peroxide. For this reaction catalytic effect was found to be significant, and old rate data was revised. Measurements on reactions involving radicals were carried out by use of pulse radiolysis technique, which also include reexamination of results by previous workers. The reactions studied are (1) oxidation of iodide ion by hydroxyl radical (2) recombination reactions of atomic iodine and diiodide ion and (3) reduction of atomic and molecular iodine either by superoxide ion or by hydroperoxyl radical

  17. Measurement of Normal and Friction Forces in a Rolling Process

    DEFF Research Database (Denmark)

    Henningsen, Poul; Arentoft, Mogens; Wanheim, Tarras

    2004-01-01

    by the fric-tion conditions. To achieve this important informa-tion, measurements of the normal pressure and friction stresses in the deformation zone are re-quested. The direction of the friction stresses is changing during the rolling gap. At the entrance of the de-formation zone, the peripherical velocity...... of the roll is higher than for the incoming material, which causes frictional stresses at the material acting in the rolling direction. At the outlet of the rolling gap, the velocity of the deformed material exceeds the velocity of the roll, generating frictional stresses contrary to the direction of rolling....... In a narrow area in the deformation zone, the velocity of the de-formed material is equal to the velocity of the rolls. This area or line is named “neutral line”. The posi-tion of the neutral line depends on friction, reduc-tion ratio, diameter of the rolls, and width of the sheet....

  18. Subsurface measurement of nanostructures on GaAs by electrostatic force microscopy

    International Nuclear Information System (INIS)

    Yamada, Fumihiko; Kamiya, Itaru

    2013-01-01

    The size of surface buried oxide nanostructures are measured by electrostatic force microscopy (EFM). In contrast to atomic force microscopy that cannot probe subsurface structures and thickness, we show that EFM data include information about the thickness of individual nanostructures, consequently allowing us to determine the thickness of buried nanostructures on semiconductor substrates. We further show that this measurement can be performed simultaneously with AFM using EFM modulation spectroscopy.

  19. Methodological Issues in Measures of Imitative Reaction Times

    Science.gov (United States)

    Aicken, Michael D.; Wilson, Andrew D.; Williams, Justin H. G.; Mon-Williams, Mark

    2007-01-01

    Ideomotor (IM) theory suggests that observing someone else perform an action activates an internal motor representation of that behaviour within the observer. Evidence supporting the case for an ideomotor theory of imitation has come from studies that show imitative responses to be faster than the same behavioural measures performed in response to…

  20. Recoil range distribution measurement in 20Ne + 181Ta reaction

    International Nuclear Information System (INIS)

    Tripathi, R.; Sudarshan, K.; Goswami, A.; Guin, R.; Reddy, A.V.R.

    2005-01-01

    In order to investigate linear momentum transfer in various transfer channels in 20 Ne + 181 Ta, recoil range distribution measurements have been carried out at E lab = 180 MeV, populating significant number of l-waves above l crit

  1. Workshop on the next plan for the study of 'physics of fast neutron reactions and measurements'

    International Nuclear Information System (INIS)

    1985-03-01

    A work shop titled ''Physics of fast neutron reaction and measurements'' was held on 25 December 1984, where discussions were made on the new approach and techniques for neutron measurements. The possibilities of experimental tests with AVF cyclotron was also discussed. The followings are the list of papers presented at the work shop (all papers are written in Japanese except for the abstracts). (1) Monoenergetic neutron beam in Tohoku Cyclotron. (2) Spin-dependent response probed in (p,n) and (n,p) reactions. (3) Measurement of D(n,p) 2n reaction and instrumentation for (n,x) reactions in the 40 - 80 MeV region. (4) Two comments related to the neutron reaction. (5) High energy neutron production facilities in the world and a possibility of neutron induced reaction experiments at RCNP. (6) A neutron counter by detection of recoil protons with solid state detectors and development of neutron source by heavy ions. (7) The measurement of neutrons with the recoil detector. (8) Polarization transfer measurements (Py, Dss, Ds 1 , · · ·) with fast neutron beams. (9) Neutron elastic scattering. (10) Neutron capture gamma reaction and effective charge. (11) Comparison between neutron and charged particle induced reactions. (12) Study of giant resonances by fast neutrons. (Aoki, K.)

  2. Angular distribution and cross section measurement for 64Zn(n,α)61Ni reaction

    International Nuclear Information System (INIS)

    Yuan Jing; Chen Zemin; Dledenov, Y.M.; Sedysheva, M.; Khuuknenkhuu, G.

    2001-01-01

    Using a gridded ionization chamber, the differential cross section for 64 Zn(n,α) 61 Ni reaction was measured at 5.0, 5.7 and 6.7 MeV. The neutrons were produced through D(d,n) 3 He reaction. Absolute neutron flux was determined through 238 U(n,f) reaction. The results show obviously backward peak in the center of mass reference system

  3. Differential cross section measurement for the 6Li(n,t)4He Reaction

    International Nuclear Information System (INIS)

    Zhang Guohui; Tang Guoyou; Chen Jinxiang; Shi Zhaomin

    2002-01-01

    The differential cross sections and integrated cross sections of the 6 Li(n,t) 4 He reaction were measured at 1.85 and 2.67 MeV by using a gridded ionization chamber. Neutrons were produced through the T(p, n) 3 He reaction. The absolute neutron flux was determined through the 238 U(n, f) reaction. Present results are compared with existing data

  4. Differential cross section measurement for the {sup 6}Li(n,t){sup 4}He Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Guohui, Zhang; Guoyou, Tang; Jinxiang, Chen; Zhaomin, Shi [Beijing Univ., Beijing (China). Inst. of Heavy Ion Physics and MOE Key Laboratory of Heavy Ion Physics; Zemin, Chen [Tsinghua Univ., Beijing (China). Dept. of Physics; Gledenov, Yu M; Sedysheva, M; Khuukhenkhuu, G [Joint Institute for Nuclear Research, Frank Laboratory of Neutron Physics, Dubna (Russian Federation)

    2002-06-01

    The differential cross sections and integrated cross sections of the {sup 6}Li(n,t){sup 4}He reaction were measured at 1.85 and 2.67 MeV by using a gridded ionization chamber. Neutrons were produced through the T(p, n){sup 3}He reaction. The absolute neutron flux was determined through the {sup 238}U(n, f) reaction. Present results are compared with existing data.

  5. Digital design and fabrication of simulation model for measuring orthodontic force.

    Science.gov (United States)

    Liu, Yun-Feng; Zhang, Peng-Yuan; Zhang, Qiao-Fang; Zhang, Jian-Xing; Chen, Jie

    2014-01-01

    Three dimensional (3D) forces are the key factors for determining movement of teeth during orthodontic treatment. Designing precise forces and torques on tooth before treatment can result accurate tooth movements, but it is too difficult to realize. In orthodontic biomechanical systems, the periodontal tissues, including bones, teeth, and periodontal ligaments (PDL), are affected by braces, and measuring the forces applied on the teeth by braces should be based on a simulated model composed of these three types of tissues. This study explores the design and fabrication of a simulated oral model for 3D orthodontic force measurements. Based on medical image processing, tissue reconstruction, 3D printing, and PDL simulation and testing, a model for measuring force was designed and fabricated, which can potentially be used for force prediction, design of treatment plans, and precise clinical operation. The experiment illustrated that bi-component silicones with 2:8 ratios had similar mechanical properties to PDL, and with a positioning guide, the teeth were assembled in the mandible sockets accurately, and so a customized oral model for 3D orthodontic force measurement was created.

  6. Evaluation of gait characteristics and ground reaction forces in cognitively declined older adults with an emphasis on slip-induced falls.

    Science.gov (United States)

    Lockhart, Thurmon; Kim, Sukwon; Kapur, Radhika; Jarrott, Shannon

    2009-01-01

    The objective of the present study was to evaluate the relationship between gait adaptation and slip/fall risk of older adults with cognitive impairments. The study investigated the gait characteristics of six healthy older adults and five older adults with dementia. Participants walked on an instrumented walkway at their preferred walking speeds. After ensuring that the preferred walking speeds were consistent, participants' natural posture and ground reaction forces were measured. The results suggested that participants with dementia walked more cautiously yet demanded more friction at the shoe/floor interface at the time of heel contact, increasing the risk of slip initiation. To reduce the risk of slip-induced falls among older adults with dementia, specific gait training to reduce friction demand requirements by increasing the transfer speed of the whole body mass is suggested.

  7. Design and testing of an innovative measurement device for tyre-road contact forces

    Science.gov (United States)

    Cheli, F.; Braghin, F.; Brusarosco, M.; Mancosu, F.; Sabbioni, E.

    2011-08-01

    The measurement of tyre-road contact forces is the first step towards the development of new control systems for improving vehicle safety and performances. Tyre-road contact forces measurement systems are very expensive and significantly modify the unsprung masses of the vehicle as well as the rotational inertia of the tyres. Thus, vehicle dynamics results are significantly affected. As a consequence, the measured contact forces do not correspond to the contact forces under real working conditions. A new low-cost tyre-road contact forces measurement system is proposed in this paper that can be applied to passenger cars. Its working principle is based on the measurement of three deformations of the wheel rim through strain gauges. The tyre-rim assembly is thus turned into a sensor for tyre-road contact forces. The influence of the strain gauges position onto the measurement results has been assessed through finite element simulations and experimental tests. It has been proven that, for a large variety of rims, the strain gauge position that leads to high signal-to-noise ratios is almost the same. A dynamic calibration procedure has been developed in order to allow the reconstruction of contact force and torque components once per wheel turn. The capability of the developed device to correctly estimate tyre-road contact forces has been assessed, in a first stage, through indoor laboratory experimental test on an MTS Flat-Trac ® testing machine. Results show that the implemented measuring system allows to reconstruct contact forces once per wheel turn with a precision that is comparable to that of existing high-cost measurement systems. Subsequently, outdoor tests with a vehicle having all four wheels equipped with the developed measuring device have also been performed. Reliability of the measurements provided by the developed sensor has been assessed by comparing the global measured longitudinal/lateral forces and the product of the measured longitudinal

  8. Quantitative measurement of solvation shells using frequency modulated atomic force microscopy

    Science.gov (United States)

    Uchihashi, T.; Higgins, M.; Nakayama, Y.; Sader, J. E.; Jarvis, S. P.

    2005-03-01

    The nanoscale specificity of interaction measurements and additional imaging capability of the atomic force microscope make it an ideal technique for measuring solvation shells in a variety of liquids next to a range of materials. Unfortunately, the widespread use of atomic force microscopy for the measurement of solvation shells has been limited by uncertainties over the dimensions, composition and durability of the tip during the measurements, and problems associated with quantitative force calibration of the most sensitive dynamic measurement techniques. We address both these issues by the combined use of carbon nanotube high aspect ratio probes and quantifying the highly sensitive frequency modulation (FM) detection technique using a recently developed analytical method. Due to the excellent reproducibility of the measurement technique, additional information regarding solvation shell size as a function of proximity to the surface has been obtained for two very different liquids. Further, it has been possible to identify differences between chemical and geometrical effects in the chosen systems.

  9. A novel integrated multifunction micro-sensor for three-dimensional micro-force measurements.

    Science.gov (United States)

    Wang, Weizhong; Zhao, Yulong; Qin, Yafei

    2012-01-01

    An integrated multifunction micro-sensor for three-dimensional micro-force precision measurement under different pressure and temperature conditions is introduced in this paper. The integrated sensor consists of three kinds of sensors: a three-dimensional micro-force sensor, an absolute pressure sensor and a temperature sensor. The integrated multifunction micro-sensor is fabricated on silicon wafers by micromachining technology. Different doping doses of boron ion, placement and structure of resistors are tested for the force sensor, pressure sensor and temperature sensor to minimize the cross interference and optimize the properties. A glass optical fiber, with a ladder structure and sharp tip etched by buffer oxide etch solution, is glued on the micro-force sensor chip as the tactile probe. Experimental results show that the minimum force that can be detected by the force sensor is 300 nN; the lateral sensitivity of the force sensor is 0.4582 mV/μN; the probe length is linearly proportional to sensitivity of the micro-force sensor in lateral; the sensitivity of the pressure sensor is 0.11 mv/KPa; the sensitivity of the temperature sensor is 5.836 × 10(-3) KΩ/°C. Thus it is a cost-effective method to fabricate integrated multifunction micro-sensors with different measurement ranges that could be used in many fields.

  10. A Novel Integrated Multifunction Micro-Sensor for Three-Dimensional Micro-Force Measurements

    Directory of Open Access Journals (Sweden)

    Yafei Qin

    2012-03-01

    Full Text Available An integrated multifunction micro-sensor for three-dimensional micro-force precision measurement under different pressure and temperature conditions is introduced in this paper. The integrated sensor consists of three kinds of sensors: a three-dimensional micro-force sensor, an absolute pressure sensor and a temperature sensor. The integrated multifunction micro-sensor is fabricated on silicon wafers by micromachining technology. Different doping doses of boron ion, placement and structure of resistors are tested for the force sensor, pressure sensor and temperature sensor to minimize the cross interference and optimize the properties. A glass optical fiber, with a ladder structure and sharp tip etched by buffer oxide etch solution, is glued on the micro-force sensor chip as the tactile probe. Experimental results show that the minimum force that can be detected by the force sensor is 300 nN; the lateral sensitivity of the force sensor is 0.4582 mV/μN; the probe length is linearly proportional to sensitivity of the micro-force sensor in lateral; the sensitivity of the pressure sensor is 0.11 mv/KPa; the sensitivity of the temperature sensor is 5.836 × 10−3 KΩ/°C. Thus it is a cost-effective method to fabricate integrated multifunction micro-sensors with different measurement ranges that could be used in many fields.

  11. Accuracy of force and center of pressure measures of the Wii Balance Board.

    Science.gov (United States)

    Bartlett, Harrison L; Ting, Lena H; Bingham, Jeffrey T

    2014-01-01

    The Nintendo Wii Balance Board (WBB) is increasingly used as an inexpensive force plate for assessment of postural control; however, no documentation of force and COP accuracy and reliability is publicly available. Therefore, we performed a standard measurement uncertainty analysis on 3 lightly and 6 heavily used WBBs to provide future users with information about the repeatability and accuracy of the WBB force and COP measurements. Across WBBs, we found the total uncertainty of force measurements to be within ± 9.1N, and of COP location within ± 4.1mm. However, repeatability of a single measurement within a board was better (4.5 N, 1.5mm), suggesting that the WBB is best used for relative measures using the same device, rather than absolute measurement across devices. Internally stored calibration values were comparable to those determined experimentally. Further, heavy wear did not significantly degrade performance. In combination with prior evaluation of WBB performance and published standards for measuring human balance, our study provides necessary information to evaluate the use of the WBB for analysis of human balance control. We suggest the WBB may be useful for low-resolution measurements, but should not be considered as a replacement for laboratory-grade force plates. Published by Elsevier B.V.

  12. Measuring adhesion on rough surfaces using atomic force microscopy with a liquid probe

    Directory of Open Access Journals (Sweden)

    Juan V. Escobar

    2017-04-01

    Full Text Available We present a procedure to perform and interpret pull-off force measurements during the jump-off-contact process between a liquid drop and rough surfaces using a conventional atomic force microscope. In this method, a micrometric liquid mercury drop is attached to an AFM tipless cantilever to measure the force required to pull this drop off a rough surface. We test the method with two surfaces: a square array of nanometer-sized peaks commonly used for the determination of AFM tip sharpness and a multi-scaled rough diamond surface containing sub-micrometer protrusions. Measurements are carried out in a nitrogen atmosphere to avoid water capillary interactions. We obtain information about the average force of adhesion between a single peak or protrusion and the liquid drop. This procedure could provide useful microscopic information to improve our understanding of wetting phenomena on rough surfaces.

  13. Changes in ground reaction force during a rebound-jump task after hip strength training for single-sided ankle dorsiflexion restriction.

    Science.gov (United States)

    Kondo, Hitoshi; Someya, Fujiko

    2016-01-01

    [Purpose] Lateral ankle sprains are common injuries suffered while playing sports, and abnormal forward- and inward-directed ground reaction force occurs during a jumping task. However, the influence of hip muscle strength training on jumping performance after ankle injuries has not been fully examined. This study thus examined changes in ground reaction force during a rebound-jump task after training to strengthen hip muscles. [Subjects and Methods] Ten of 30 female high school basketball players were assigned as subjects who showed a difference of 7 or more degrees in dorsiflexion ranges between the bilateral ankles. The subjects underwent 12 weeks of training to strengthen hip abductors and external rotators. Comparisons between before and after training were made regarding ground reaction force components, hip and knee joint angles, percentage of maximum voluntary contraction in leg muscles, and muscle strength of hip muscles during the rebound-jump task. [Results] After training, the subjects showed increased strength of external rotator muscles, increased percentage of maximum voluntary contraction in the gluteus medius muscle, decreased inward ground reaction force, and increased flexion angles of the hip and knee joints. [Conclusion] This study suggests that training to strengthen hip muscles may ameliorate the inward ground reaction force in athletes with ankle dorsiflexion restriction.

  14. Estimation and prediction of convection-diffusion-reaction systems from point measurement

    NARCIS (Netherlands)

    Vries, D.

    2008-01-01

    Different procedures with respect to estimation and prediction of systems characterized by convection, diffusion and reactions on the basis of point measurement data, have been studied. Two applications of these convection-diffusion-reaction (CDR) systems have been used as a case study of the

  15. Measurement of reaction rates of interest in stellar structure and evolution

    International Nuclear Information System (INIS)

    Terrasi, F.; D''Onofrio, A.; Campajola, L.; Imbriani, G.; Gialanella, L.; Greife, U.; Rolfs, C.; Strieder, F.; Trautvetter, H.P.; Roca, V.; Romano, M.; Straniero, O.

    1998-01-01

    Accurate determinations of reaction rates at astrophysical energies are very important in stellar structure and evolution studies. The cases of two key reactions, namely 7 Be(p,γ) 8 B and 12 C(α,γ) 16 O are discussed, both from the point of view of their astrophysical interest and of the experimental difficulties in the measurement of their cross section. (orig.)

  16. Timing differences in the generation of ground reaction forces between the initial and secondary landing phases of the drop vertical jump ☆

    Science.gov (United States)

    Bates, Nathaniel A.; Ford, Kevin R.; Myer, Gregory D.; Hewett, Timothy E.

    2014-01-01

    Background Rapid impulse loads imparted on the lower extremity from ground contact when landing from a jump may contribute to ACL injury prevalence in female athletes. The drop jump and drop landing tasks enacted in the first and second landings of drop vertical jumps, respectively, have been shown to elicit separate neuromechanical responses. We examined the first and second landings of a drop vertical jump for differences in landing phase duration, time to peak force, and rate of force development. Methods 239 adolescent female basketball players completed drop vertical jumps from an initial height of 31 cm. In-ground force platforms and a three dimensional motion capture system recorded force and positional data for each trial. Findings Between the first and second landing, rate of force development experienced no change (P > 0.62), landing phase duration decreased (P = 0.01), and time to peak ground reaction force increased (P 0.12). Interpretation The current results have important implications for the future assessment of ACL injury risk behaviors. Rate of force development remained unchanged between first and second landings from equivalent fall height, while time to peak reaction force increased during the second landing. Neither factor was dependent on the total time duration of landing phase, which decreased during the second landing. Shorter time to peak force may increase ligament strain and better represent the abrupt joint loading that is associated with ACL injury risk. PMID:23899938

  17. Timing differences in the generation of ground reaction forces between the initial and secondary landing phases of the drop vertical jump.

    Science.gov (United States)

    Bates, Nathaniel A; Ford, Kevin R; Myer, Gregory D; Hewett, Timothy E

    2013-08-01

    Rapid impulse loads imparted on the lower extremity from ground contact when landing from a jump may contribute to ACL injury prevalence in female athletes. The drop jump and drop landing tasks enacted in the first and second landings of drop vertical jumps, respectively, have been shown to elicit separate neuromechanical responses. We examined the first and second landings of a drop vertical jump for differences in landing phase duration, time to peak force, and rate of force development. 239 adolescent female basketball players completed drop vertical jumps from an initial height of 31cm. In-ground force platforms and a three dimensional motion capture system recorded force and positional data for each trial. Between the first and second landing, rate of force development experienced no change (P>0.62), landing phase duration decreased (P=0.01), and time to peak ground reaction force increased (P0.12). The current results have important implications for the future assessment of ACL injury risk behaviors. Rate of force development remained unchanged between first and second landings from equivalent fall height, while time to peak reaction force increased during the second landing. Neither factor was dependent on the total time duration of landing phase, which decreased during the second landing. Shorter time to peak force may increase ligament strain and better represent the abrupt joint loading that is associated with ACL injury risk. © 2013.

  18. Calibrated atomic force microscope measurements of vickers hardness indentations and tip production and characterisation for scanning tunelling microscope

    DEFF Research Database (Denmark)

    Jensen, Carsten P.

    Calibrated atomic force microscope measurements of vickers hardness indentations and tip production and characterisation for scanning tunelling microscope......Calibrated atomic force microscope measurements of vickers hardness indentations and tip production and characterisation for scanning tunelling microscope...

  19. An in-fiber Bragg grating sensor for contact force and stress measurements in articular joints

    International Nuclear Information System (INIS)

    Dennison, Christopher R; Wild, Peter M; Wilson, David R; Gilbart, Michael K

    2010-01-01

    We present an in-fiber Bragg grating-based sensor (240 µm diameter) for contact force/stress measurements in articular joints. The contact force sensor and another Bragg grating-based pressure sensor (400 µm diameter) are used to conduct the first simultaneous measurements of contact force/stress and fluid pressure in intact cadaveric human hips. The contact force/stress sensor addresses limitations associated with stress-sensitive films, the current standard tools for contact measurements in joints, including cartilage modulus-dependent sensitivity of films and the necessity to remove biomechanically relevant anatomy to implant the films. Because stress-sensitive films require removal of anatomy, it has been impossible to validate the mechanical rationale underlying preventive or corrective surgeries, which repair these anatomies, by conducting simultaneous stress and pressure measurements in intact hips. Methods are presented to insert the Bragg grating-based sensors into the joint, while relevant anatomy is left largely intact. Sensor performance is predicted using numerical models and the predicted sensitivity is verified through experimental calibrations. Contact force/stress and pressure measurements in cadaveric joints exhibited repeatability. With further validation, the Bragg grating-based sensors could be used to study the currently unknown relationships between contact forces and pressures in both healthy and degenerated joints

  20. Instrumented figure skating blade for measuring on-ice skating forces

    Science.gov (United States)

    Acuña, S. A.; Smith, D. M.; Robinson, J. M.; Hawks, J. C.; Starbuck, P.; King, D. L.; Ridge, S. T.; Charles, S. K.

    2014-12-01

    Competitive figure skaters experience substantial, repeated impact loading during jumps and landings. Although these loads, which are thought to be as high as six times body weight, can lead to overuse injuries, it is not currently possible to measure these forces on-ice. Consequently, efforts to improve safety for skaters are significantly limited. Here we present the development of an instrumented figure skating blade for measuring forces on-ice. The measurement system consists of strain gauges attached to the blade, Wheatstone bridge circuit boards, and a data acquisition device. The system is capable of measuring forces in the vertical and horizontal directions (inferior-superior and anterior-posterior directions, respectively) in each stanchion with a sampling rate of at least 1000 Hz and a resolution of approximately one-tenth of body weight. The entire system weighs 142 g and fits in the space under the boot. Calibration between applied and measured force showed excellent agreement (R > 0.99), and a preliminary validation against a force plate showed good predictive ability overall (R ≥ 0.81 in vertical direction). The system overestimated the magnitude of the first and second impact peaks but detected their timing with high accuracy compared to the force plate.

  1. Prestress Force Identification for Externally Prestressed Concrete Beam Based on Frequency Equation and Measured Frequencies

    Directory of Open Access Journals (Sweden)

    Luning Shi

    2014-01-01

    Full Text Available A prestress force identification method for externally prestressed concrete uniform beam based on the frequency equation and the measured frequencies is developed. For the purpose of the prestress force identification accuracy, we first look for the appropriate method to solve the free vibration equation of externally prestressed concrete beam and then combine the measured frequencies with frequency equation to identify the prestress force. To obtain the exact solution of the free vibration equation of multispan externally prestressed concrete beam, an analytical model of externally prestressed concrete beam is set up based on the Bernoulli-Euler beam theory and the function relation between prestress variation and vibration displacement is built. The multispan externally prestressed concrete beam is taken as the multiple single-span beams which must meet the bending moment and rotation angle boundary conditions, the free vibration equation is solved using sublevel simultaneous method and the semi-analytical solution of the free vibration equation which considered the influence of prestress on section rigidity and beam length is obtained. Taking simply supported concrete beam and two-span concrete beam with external tendons as examples, frequency function curves are obtained with the measured frequencies into it and the prestress force can be identified using the abscissa of the crosspoint of frequency functions. Identification value of the prestress force is in good agreement with the test results. The method can accurately identify prestress force of externally prestressed concrete beam and trace the trend of effective prestress force.

  2. Endogenous electromagnetic forces in living cells: implications for transfer or reaction components

    Czech Academy of Sciences Publication Activity Database

    Pokorný, Jiří

    2001-01-01

    Roč. 20, č. 1 (2001), s. 59-73 ISSN 1061-9526. [Electromagnetic Aspects of Selforganization in Biology. Prague, 09.07.2000-12.07.2000] R&D Projects: GA ČR GA102/97/0867 Grant - others:EU COST (XE) OC 244BIS.10 Institutional research plan: CEZ:AV0Z2067918 Keywords : electromagnetic fields * cellular biophysics * field strength measurement Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.333, year: 2001

  3. Measuring lip force by oral screens. Part 1: Importance of screen size and individual variability.

    Science.gov (United States)

    Wertsén, Madeleine; Stenberg, Manne

    2017-06-01

    To reduce drooling and facilitate food transport in rehabilitation of patients with oral motor dysfunction, lip force can be trained using an oral screen. Longitudinal studies evaluating the effect of training require objective methods. The aim of this study was to evaluate a method for measuring lip strength, to investigate normal values and fluctuation of lip force in healthy adults on 1 occasion and over time, to study how the size of the screen affects the force, to evaluate the most appropriate measure of reliability, and to identify force performed in relation to gender. Three different sizes of oral screens were used to measure the lip force for 24 healthy adults on 3 different occasions, during a period of 6 months, using an apparatus based on strain gauge. The maximum lip force as evaluated with this method depends on the area of the screen size. By calculating the projected area of the screen, the lip force could be normalized to an oral screen pressure quantity expressed in kPa, which can be used for comparing measurements from screens with different sizes. Both the mean value and standard deviation were shown to vary between individuals. The study showed no differences regarding gender and only small variation with age. Normal variation over time (months) may be up to 3 times greater than the standard error of measurement at a certain occasion. The lip force increases in relation to the projected area of the screen. No general standard deviation can be assigned to the method and all measurements should be analyzed individually based on oral screen pressure to compensate for different screen sizes.

  4. Surface Forces Apparatus measurements of interactions between rough and reactive calcite surfaces.

    Science.gov (United States)

    Dziadkowiec, Joanna; Javadi, Shaghayegh; Bratvold, Jon Einar; Nilsen, Ola; Røyne, Anja

    2018-05-28

    Nm-range forces acting between calcite surfaces in water affect macroscopic properties of carbonate rocks and calcite-based granular materials, and are significantly influenced by calcite surface recrystallization. We suggest that the repulsive mechanical effects related to nm-scale surface recrystallization of calcite in water could be partially responsible for the observed decrease of cohesion in calcitic rocks saturated with water. Using the Surface Forces Apparatus (SFA), we simultaneously followed the calcite reactivity and measured the forces in water in two surface configurations: between two rough calcite surfaces (CC), or between rough calcite and a smooth mica surface (CM). We used nm-scale rough, polycrystalline calcite films prepared by Atomic Layer Deposition (ALD). We measured only repulsive forces in CC in CaCO 3 -saturated water, which was related to roughness and possibly to repulsive hydration effects. Adhesive or repulsive forces were measured in CM in CaCO 3 -saturated water depending on calcite roughness, and the adhesion was likely enhanced by electrostatic effects. The pull-off adhesive force in CM became stronger with time and this increase was correlated with a decrease of roughness at contacts, which parameter could be estimated from the measured force-distance curves. That suggested a progressive increase of real contact areas between the surfaces, caused by gradual pressure-driven deformation of calcite surface asperities during repeated loading-unloading cycles. Reactivity of calcite was affected by mass transport across nm to µm-thick gaps between the surfaces. Major roughening was observed only for the smoothest calcite films, where gaps between two opposing surfaces were nm-thick over µm-sized areas, and led to force of crystallization that could overcome confining pressures of the order of MPa. Any substantial roughening of calcite caused a significant increase of the repulsive mechanical force contribution.

  5. Estimation of Joint Forces and Moments for the In-Run and Take-Off in Ski Jumping Based on Measurements with Wearable Inertial Sensors

    Directory of Open Access Journals (Sweden)

    Grega Logar

    2015-05-01

    Full Text Available This study uses inertial sensors to measure ski jumper kinematics and joint dynamics, which was until now only a part of simulation studies. For subsequent calculation of dynamics in the joints, a link-segment model was developed. The model relies on the recursive Newton–Euler inverse dynamics. This approach allowed the calculation of the ground reaction force at take-off. For the model validation, four ski jumpers from the National Nordic center performed a simulated jump in a laboratory environment on a force platform; in total, 20 jumps were recorded. The results fit well to the reference system, presenting small errors in the mean and standard deviation and small root-mean-square errors. The error is under 12% of the reference value. For field tests, six jumpers participated in the study; in total, 28 jumps were recorded. All of the measured forces and moments were within the range of prior simulated studies. The proposed system was able to indirectly provide the values of forces and moments in the joints of the ski-jumpers’ body segments, as well as the ground reaction force during the in-run and take-off phases in comparison to the force platform installed on the table. Kinematics assessment and estimation of dynamics parameters can be applied to jumps from any ski jumping hill.

  6. Estimation of joint forces and moments for the in-run and take-off in ski jumping based on measurements with wearable inertial sensors.

    Science.gov (United States)

    Logar, Grega; Munih, Marko

    2015-05-13

    This study uses inertial sensors to measure ski jumper kinematics and joint dynamics, which was until now only a part of simulation studies. For subsequent calculation of dynamics in the joints, a link-segment model was developed. The model relies on the recursive Newton-Euler inverse dynamics. This approach allowed the calculation of the ground reaction force at take-off. For the model validation, four ski jumpers from the National Nordic center performed a simulated jump in a laboratory environment on a force platform; in total, 20 jumps were recorded. The results fit well to the reference system, presenting small errors in the mean and standard deviation and small root-mean-square errors. The error is under 12% of the reference value. For field tests, six jumpers participated in the study; in total, 28 jumps were recorded. All of the measured forces and moments were within the range of prior simulated studies. The proposed system was able to indirectly provide the values of forces and moments in the joints of the ski-jumpers' body segments, as well as the ground reaction force during the in-run and take-off phases in comparison to the force platform installed on the table. Kinematics assessment and estimation of dynamics parameters can be applied to jumps from any ski jumping hill.

  7. Methodological issues in measures of imitative reaction times.

    Science.gov (United States)

    Aicken, Michael D; Wilson, Andrew D; Williams, Justin H G; Mon-Williams, Mark

    2007-04-01

    Ideomotor (IM) theory suggests that observing someone else perform an action activates an internal motor representation of that behaviour within the observer. Evidence supporting the case for an ideomotor theory of imitation has come from studies that show imitative responses to be faster than the same behavioural measures performed in response to spatial cues. In an attempt to replicate these findings, we manipulated the salience of the visual cue and found that we could reverse the advantage of the imitative cue over the spatial cue. We suggest that participants utilised a simple visuomotor mechanism to perform all aspects of this task, with performance being driven by the relative visual salience of the stimuli. Imitation is a more complex motor skill that would constitute an inefficient strategy for rapid performance.

  8. The use of piezoelectric bimorph transducers to measure forces in colloidal systems

    International Nuclear Information System (INIS)

    Stewart, A.M.

    1996-01-01

    The Surface Force Apparatus developed in this Department has proved useful for the measurement of colloidal forces between transparent surfaces in liquids and gases at surface separations of 1 nm up to 500 nm. The distance between the surfaces is measured by the interferometry of white light, and the force is measured from the movement of one of the surfaces that is attached to a cantilever spring which deflects under the influence of the force. In the present work an analysis is made of the effect of the errors introduced at a longer time scale by bimorph drift and decay upon accuracy of measurement. For direct measurements the errors will be small provided that the time constant of the bimorph, given by the product of its capacitance and amplifier input impedance, is much larger than the total time of measurement. With the force-feedback technique the errors will be negligible provided that, in addition the integrator time constant is much smaller than the bimorph time constant, a condition easily satisfied. In is important to use an amplifier with a very high input impedance to buffer bimorphs used for this type of measurement

  9. Measurement of the force on microparticles in a beam of energetic ions and neutral atoms

    International Nuclear Information System (INIS)

    Trottenberg, Thomas; Schneider, Viktor; Kersten, Holger

    2010-01-01

    The force on microparticles in an energetic ion beam is investigated experimentally. Hollow glass microspheres are injected into the vertically upward directed beam and their trajectories are recorded with a charge-coupled device camera. The net force on the particles is determined by means of the measured vertical acceleration. The resulting beam pressures are compared with Faraday cup measurements of the ion current density and calorimetric measurements of the beam power density. Due to the neutral gas background, the beam consists, besides the ions, of energetic neutral atoms produced by charge-exchange collisions. It is found that the measured composition of the drag force by an ion and a neutral atom component agrees with a beam model that takes charge-exchange collisions into account. Special attention is paid to the momentum contribution from sputtered atoms, which is shown to be negligible in this experiment, but should become measurable in case of materials with high sputtering yields.

  10. d-3He reaction measurements during fast wave minority heating in PLT

    International Nuclear Information System (INIS)

    Chrien, R.E.; Strachan, J.D.

    1983-01-01

    Time- and energy-resolved d- 3 He fusion reactions have been measured to infer the energy of the d + or He ++ minority ions heated near their cyclotron frequency by the magnetosonic fast wave. The average energy of the reacting 3 He ions during 3 He minority heating is in the range of 100 to 400 keV, as deduced from the magnitude of the reaction rate, its decay time, and the energy spread of the proton reaction products. The observed reaction rate and its scaling with wave power and electron density and temperature are in qualitative agreement with a radial reaction rate model using the minority distribution predicted from quasilinear velocity space diffusion. Oscillations in the reaction rate are observed concurrent with sawtooth and m = 2 MHD activity in the plasma

  11. Concurrent validity and reliability of using ground reaction force and center of pressure parameters in the determination of leg movement initiation during single leg lift.

    Science.gov (United States)

    Aldabe, Daniela; de Castro, Marcelo Peduzzi; Milosavljevic, Stephan; Bussey, Melanie Dawn

    2016-09-01

    Postural adjustment evaluations during single leg lift requires the initiation of heel lift (T1) identification. T1 measured by means of motion analyses system is the most reliable approach. However, this method involves considerable workspace, expensive cameras, and time processing data and setting up laboratory. The use of ground reaction forces (GRF) and centre of pressure (COP) data is an alternative method as its data processing and setting up is less time consuming. Further, kinetic data is normally collected using frequency samples higher than 1000Hz whereas kinematic data are commonly captured using 50-200Hz. This study describes the concurrent-validity and reliability of GRF and COP measurements in determining T1, using a motion analysis system as reference standard. Kinematic and kinetic data during single leg lift were collected from ten participants. GRF and COP data were collected using one and two force plates. Displacement of a single heel marker was captured by means of ten Vicon(©) cameras. Kinetic and kinematic data were collected using a sample frequency of 1000Hz. Data were analysed in two stages: identification of key events in the kinetic data, and assessing concurrent validity of T1 based on the chosen key events with T1 provided by the kinematic data. The key event presenting the least systematic bias, along with a narrow 95% CI and limits of agreement against the reference standard T1, was the Baseline COPy event. Baseline COPy event was obtained using one force plate and presented excellent between-tester reliability. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Measurements of cutter forces and cutter temperature of boring machine in Aespoe Hard Rock Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z.X.; Kou, S.Q.; Lindqvist, P.-A. [Luleaa Univ. of Technology (Sweden)

    2001-04-01

    This report presents both the testing methods used and the testing results obtained for cutter forces and cutter temperature during field boring in Aespoe Hard Rock Laboratory. In order to estimate the strains induced by cutter forces in the cutter shaft and choose proper transducers, first a numerical simulation was performed. The simulation results indicated that the cutter forces should be measurable by ordinary strain gauges. Furthermore, an independent three-direction loading system for laboratory calibration was set up to solve force-coupling problems appearing in field measurements. By means of the established measuring system, which was proved successfully in the laboratory, the normal forces, tangential forces, and side forces of two button cutters in the boring machine were measured in the field. In addition, the temperature in the shaft of the front cutter was measured. After the measurements of the cutter forces and cutter temperature, rock core samples were taken from the bottom and the wall of the testing borehole. Then the samples were cut, polished, and examined by means of the Scanning Electron Microscope (SEM). After that, the lengths of major cracks induced by the cutters in the rock samples were measured, and an approximate relationship between the length of the medium cracks and the relevant cutter forces was obtained. This relationship was compared with the theoretical relationship established before. Finally, according to the measured results, the cracked zones around the borehole were described. The results show that: (1) there are two kinds of cracked zones: one in the borehole wall and the other in the bottom of the borehole. The depth of the cracked zone in the borehole bottom is much larger than that in the borehole wall because the maximum normal force of the front cutter is always much larger than that of the gauge cutter. (2) Each cracked zone includes a densely cracked zone and all the longest medium cracks caused by mechanical

  13. Measurement of resonance integral of the 90Sr(n,γ)91Sr reaction

    International Nuclear Information System (INIS)

    Nakamura, Shoji; Furutaka, Kazuyoshi; Wada, Hiroaki; Katoh, Toshio; Harada, Hideo; Fujii, Toshiyuki; Yamana, Hajimu

    2001-01-01

    To obtain fundamental data for research on nuclear transmutation method of radioactive wastes, the resonance integral (I 0 ) of the 90 Sr(n,γ) 91 Sr reaction was measured with an activation method. (author)

  14. Design of a fusion reaction-history measurement system with high temporal resolution

    International Nuclear Information System (INIS)

    Peng Xiaoshi; Wang Feng; Liu Shenye; Jiang Xiaohua; Tang Qi

    2010-01-01

    In order to accurately measure the history of fusion reaction for experimental study of inertial confinement fusion, we advance the design of a fusion reaction-history measurement system with high temporal resolution. The diagnostic system is composed of plastic scintillator and nose cone, an optical imaging system and the system of optic streak camera. Analyzing the capability of the system indicated that the instrument measured fusion reaction history at temporal resolution as low as 55ps and 40ps correspond to 2.45MeV DD neutrons and 14.03MeV DT neutrons. The instrument is able to measure the fusion reaction history at yields 1.5 x 10 9 DD neutrons, about 4 x 10 8 DT neutrons are required for a similar quality signal. (authors)

  15. A High Performance Sensor for Triaxial Cutting Force Measurement in Turning

    Directory of Open Access Journals (Sweden)

    You Zhao

    2015-04-01

    Full Text Available This paper presents a high performance triaxial cutting force sensor with excellent accuracy, favorable natural frequency and acceptable cross-interference for high speed turning process. Octagonal ring is selected as sensitive element of the designed sensor, which is drawn inspiration from ring theory. A novel structure of two mutual-perpendicular octagonal rings is proposed and three Wheatstone full bridge circuits are specially organized in order to obtain triaxial cutting force components and restrain cross-interference. Firstly, the newly developed sensor is tested in static calibration; test results indicate that the sensor possesses outstanding accuracy in the range of 0.38%–0.83%. Secondly, impacting modal tests are conducted to identify the natural frequencies of the sensor in triaxial directions (i.e., 1147 Hz, 1122 Hz and 2035 Hz, which implies that the devised sensor can be used for cutting force measurement in a high speed lathe when the spindle speed does not exceed 17,205 rev/min in continuous cutting condition. Finally, an application of the sensor in turning process is operated to show its performance for real-time cutting force measurement; the measured cutting forces demonstrate a good accordance with the variation of cutting parameters. Thus, the developed sensor possesses perfect properties and it gains great potential for real-time cutting force measurement in turning.

  16. Pushing nanoparticles with light — A femtonewton resolved measurement of optical scattering forces

    Directory of Open Access Journals (Sweden)

    C. Zensen

    2016-05-01

    Full Text Available Optomechanical manipulation of plasmonic nanoparticles is an area of current interest, both fundamental and applied. However, no experimental method is available to determine the forward-directed scattering force that dominates for incident light of a wavelength close to the plasmon resonance. Here, we demonstrate how the scattering force acting on a single gold nanoparticle in solution can be measured. An optically trapped 80 nm particle was repetitively pushed from the side with laser light resonant to the particle plasmon frequency. A lock-in analysis of the particle movement provides a measured value for the scattering force. We obtain a resolution of less than 3 femtonewtons which is an order of magnitude smaller than any measurement of switchable forces performed on nanoparticles in solution with single beam optical tweezers to date. We compared the results of the force measurement with Mie simulations of the optical scattering force on a gold nanoparticle and found good agreement between experiment and theory within a few fN.

  17. First Year Report: Nuclear Reaction Measurements with Radioactive Beams and Targets- Progress in Measurements of the 89Zr (n,xnyp) Reaction Cross Sections

    International Nuclear Information System (INIS)

    Joseph Cerny; Dennis Moltz; Sylvia La; Ed Morse; Larry Ahle; Lee Bernstein; Ken Moody; Kevin Roberts; Margaret Moody; James Powell; Jim O'Neil; Anthony Belian

    2004-01-01

    OAK-B135 During the underground nuclear tests in Nevada, some of the most important information was obtained by radiochemical analysis of post-test excavations. By adding small samples of refractory and rare earth elements not commonly present in the surrounding soil to the device, a detailed look could be had of the actual event. In order to properly analyze these data, several hundred cross sections are needed at a neutron energy of 14 MeV (a d-t-burn product). Although it has always been assumed that these calculations are correct, insufficient experimental data exist to corroborate this assumption. The purpose of this experiment is to measure two reaction cross sections, namely the 89 Zr (n, 2n) 88 Zr and 89 Zr (n, np) 88 Y reactions. Although the former reaction has been measured in an unpublished report ( A. A. Delucchi and W. Goishi, LANL Report LA-7841-C (1977) pp. 33-36), we intend to reduce the experimental error in this cross section. The latter cross section has not been measured. This case is much simplified because these reaction products have half-lives ∼100 days compared with ∼3 days for the target nuclide. Therefore the assay can be accomplished long after the target nuclei have decayed away

  18. Stability enhancement of an atomic force microscope for long-term force measurement including cantilever modification for whole cell deformation

    Science.gov (United States)

    Weafer, P. P.; McGarry, J. P.; van Es, M. H.; Kilpatrick, J. I.; Ronan, W.; Nolan, D. R.; Jarvis, S. P.

    2012-09-01

    Atomic force microscopy (AFM) is widely used in the study of both morphology and mechanical properties of living cells under physiologically relevant conditions. However, quantitative experiments on timescales of minutes to hours are generally limited by thermal drift in the instrument, particularly in the vertical (z) direction. In addition, we demonstrate the necessity to remove all air-liquid interfaces within the system for measurements in liquid environments, which may otherwise result in perturbations in the measured deflection. These effects severely limit the use of AFM as a practical tool for the study of long-term cell behavior, where precise knowledge of the tip-sample distance is a crucial requirement. Here we present a readily implementable, cost effective method of minimizing z-drift and liquid instabilities by utilizing active temperature control combined with a customized fluid cell system. Long-term whole cell mechanical measurements were performed using this stabilized AFM by attaching a large sphere to a cantilever in order to approximate a parallel plate system. An extensive examination of the effects of sphere attachment on AFM data is presented. Profiling of cantilever bending during substrate indentation revealed that the optical lever assumption of free ended cantilevering is inappropriate when sphere constraining occurs, which applies an additional torque to the cantilevers "free" end. Here we present the steps required to accurately determine force-indentation measurements for such a scenario. Combining these readily implementable modifications, we demonstrate the ability to investigate long-term whole cell mechanics by performing strain controlled cyclic deformation of single osteoblasts.

  19. Interaction force measurement between E. coli cells and nanoparticles immobilized surfaces by using AFM.

    Science.gov (United States)

    Zhang, Wen; Stack, Andrew G; Chen, Yongsheng

    2011-02-01

    To better understand environmental behaviors of nanoparticles (NPs), we used the atomic force microscopy (AFM) to measure interaction forces between E. coli cells and NPs immobilized on surfaces in an aqueous environment. The results showed that adhesion force strength was significantly influenced by particle size for both hematite (α-Fe(2)O(3)) and corundum (α-Al(2)O(3)) NPs whereas the effect on the repulsive force was not observed. The adhesion force decreased from 6.3±0.7nN to 0.8±0.4nN as hematite NPs increased from 26nm to 98nm in diameter. Corundum NPs exhibited a similar dependence of adhesion force on particle size. The Johnson-Kendall-Roberts (JKR) model was employed to estimate the contact area between E. coli cells and NPs, and based on the JKR model a new model that considers local effective contact area was developed. The prediction of the new model matched the size dependence of adhesion force in experimental results. Size effects on adhesion forces may originate from the difference in local effective contact areas as supported by our model. These findings provide fundamental information for interpreting the environmental behaviors and biological interactions of NPs, which barely have been addressed. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. Measurement of unsteady flow forces in inline and staggered tube bundles with fixed and vibrating tubes

    International Nuclear Information System (INIS)

    Michel, A.; Heinecke, E.; Decken, C.B. von der.

    1986-01-01

    Unsteady flow forces arising in heat exchangers with cross-flow may lead to serious vibrations of the tubes. These vibrations can destroy the tubes in the end supports or in the baffles, which would require expensive repairs. The flow forces reach unexpectedly by high values if the vibration of the tube intensifies these forces. To clear up this coupling mechanism the flow forces and the vibration amplitude were measured simultaneously in a staggered and in an inline tube bundle. Considering the tube as a one-mass oscillator excited by the flow force, the main parameters can be derived, i.e. dynamic pressure, reduced mass, eigenfrequency and damping. These parameters form a dimensionless model number describing the coherence of the vibration amplitude and the force coefficient. The validity of this number has been confirmed by varying the test conditions. With the aid of this model number, the expected force coefficient can be calculated and then using a finite-element program information can be obtained about mechanical tensions and the lifetime of the heat exchanger tubes. With this model number the results of other authors, who measured the vibration amplitude only, could be confirmed in good agreement. The experiments were carried out in air with Reynolds numbers 10 4 5 . (orig.) [de

  1. Identification of impact force acting on composite laminated plates using the radiated sound measured with microphones

    Science.gov (United States)

    Atobe, Satoshi; Nonami, Shunsuke; Hu, Ning; Fukunaga, Hisao

    2017-09-01

    Foreign object impact events are serious threats to composite laminates because impact damage leads to significant degradation of the mechanical properties of the structure. Identification of the location and force history of the impact that was applied to the structure can provide useful information for assessing the structural integrity. This study proposes a method for identifying impact forces acting on CFRP (carbon fiber reinforced plastic) laminated plates on the basis of the sound radiated from the impacted structure. Identification of the impact location and force history is performed using the sound pressure measured with microphones. To devise a method for identifying the impact location from the difference in the arrival times of the sound wave detected with the microphones, the propagation path of the sound wave from the impacted point to the sensor is examined. For the identification of the force history, an experimentally constructed transfer matrix is employed to relate the force history to the corresponding sound pressure. To verify the validity of the proposed method, impact tests are conducted by using a CFRP cross-ply laminate as the specimen, and an impulse hammer as the impactor. The experimental results confirm the validity of the present method for identifying the impact location from the arrival time of the sound wave detected with the microphones. Moreover, the results of force history identification show the feasibility of identifying the force history accurately from the measured sound pressure using the experimental transfer matrix.

  2. Soft colloidal probes for AFM force measurements between water droplets in oil

    KAUST Repository

    Vakarelski, Ivan Uriev; Li, Erqiang; Thoroddsen, Sigurdur T

    2014-01-01

    Here we introduce an extension of the atomic force microscopy (AFM) colloidal probe technique, as a simple and reliable experimental approach to measure the interaction forces between small water droplets (~80-160. μm) dispersed in oil. Small water droplets are formed by capillary breakup of a microscale water jet in air, which is forced out of a fine capillary nozzle, and deposited on a superhydrophobic substrate immersed in tetradecane oil medium. In these conditions the water droplets are very loosely attached to the superhydrophobic substrate and are easily picked up with a hydrophobic AFM cantilever to form a soft colloidal probe. Sample force measurements are conducted to demonstrate the capability of the technique.

  3. Soft colloidal probes for AFM force measurements between water droplets in oil

    KAUST Repository

    Vakarelski, Ivan Uriev

    2014-11-01

    Here we introduce an extension of the atomic force microscopy (AFM) colloidal probe technique, as a simple and reliable experimental approach to measure the interaction forces between small water droplets (~80-160. μm) dispersed in oil. Small water droplets are formed by capillary breakup of a microscale water jet in air, which is forced out of a fine capillary nozzle, and deposited on a superhydrophobic substrate immersed in tetradecane oil medium. In these conditions the water droplets are very loosely attached to the superhydrophobic substrate and are easily picked up with a hydrophobic AFM cantilever to form a soft colloidal probe. Sample force measurements are conducted to demonstrate the capability of the technique.

  4. Direct measurement and modulation of single-molecule coordinative bonding forces in a transition metal complex

    DEFF Research Database (Denmark)

    Hao, Xian; Zhu, Nan; Gschneidtner, Tina

    2013-01-01

    remain a daunting challenge. Here we demonstrate an interdisciplinary and systematic approach that enables measurement and modulation of the coordinative bonding forces in a transition metal complex. Terpyridine is derived with a thiol linker, facilitating covalent attachment of this ligand on both gold...... substrate surfaces and gold-coated atomic force microscopy tips. The coordination and bond breaking between terpyridine and osmium are followed in situ by electrochemically controlled atomic force microscopy at the single-molecule level. The redox state of the central metal atom is found to have...

  5. High force measurement sensitivity with fiber Bragg gratings fabricated in uniform-waist fiber tapers

    International Nuclear Information System (INIS)

    Wieduwilt, Torsten; Brückner, Sven; Bartelt, Hartmut

    2011-01-01

    Fiber Bragg gratings inscribed in the waist of tapered photosensitive fibers offer specific attractive properties for sensing applications. A small-diameter fiber reduces structural influences for imbedded fiber sensing elements. In the case of application as a force-sensing element for tensile forces, sensitivity scales inversely with the fiber cross-sectional area. It is therefore possible to increase force sensitivity by several orders of magnitude compared to Bragg grating sensors in conventionally sized fibers. Special requirements for such Bragg grating arrangements are discussed and experimental measurements for different fiber taper diameters down to 4 µm are presented

  6. Measurement of Forces and Torques during Non Homogeneous Material Drilling Operation

    OpenAIRE

    Mohd Hazny Aziz; Muhammad Azmi Ayub

    2011-01-01

    The purpose of this study is to measure the forces and toques that produce in the drilling process of non-homogenous material (bone). An automated five degree of freedom CRS CataLyst-5 robot used during the drilling process together with the six degree freedom of force toque sensor. A force torque controller that built in Matlab Simulink environment is used to control the drilling process of the robot. Different feed rate will be used during the experimental of the drilling process. The sen...

  7. On the deduction of chemical reaction pathways from measurements of time series of concentrations.

    Science.gov (United States)

    Samoilov, Michael; Arkin, Adam; Ross, John

    2001-03-01

    We discuss the deduction of reaction pathways in complex chemical systems from measurements of time series of chemical concentrations of reacting species. First we review a technique called correlation metric construction (CMC) and show the construction of a reaction pathway from measurements on a part of glycolysis. Then we present two new improved methods for the analysis of time series of concentrations, entropy metric construction (EMC), and entropy reduction method (ERM), and illustrate (EMC) with calculations on a model reaction system. (c) 2001 American Institute of Physics.

  8. Setup for fission and evaporation cross-section measurements in reactions induced by secondary beams

    International Nuclear Information System (INIS)

    Hassan, A.A.; Luk'yanov, S.M.; Kalpakchieva, R.; Skobelev, N.K.; Penionzhkevich, Yu.Eh.; Dlouhy, Z.; Radnev, S.; Poroshin, N.V.

    2002-01-01

    A setup for studying reactions induced by secondary radioactive beams has been constructed. It allows simultaneous measurement of α-particle and fission fragment energy spectra. By measuring the α-particles, identification of evaporation residues is achieved. A set of three targets can be used so as to ensure sufficient statistics. Two silicon detectors, located at 90 degrees to the secondary beam direction, face each target, thus covering 30% of the solid angle. This experimental setup is to be used to obtain excitation functions of fusion-fission reactions and of reactions leading to evaporation residue production

  9. Measurement of the traction force of biological cells by digital holography

    Science.gov (United States)

    Yu, Xiao; Cross, Michael; Liu, Changgeng; Clark, David C.; Haynie, Donald T.; Kim, Myung K.

    2011-01-01

    The traction force produced by biological cells has been visualized as distortions in flexible substrata. We have utilized quantitative phase microscopy by digital holography (DH-QPM) to study the wrinkling of a silicone rubber film by motile fibroblasts. Surface deformation and the cellular traction force have been measured from phase profiles in a direct and straightforward manner. DH-QPM is shown to provide highly efficient and versatile means for quantitatively analyzing cellular motility. PMID:22254175

  10. Measurement of internal forces in superconducting accelerator magnets with strain gauge transducers

    International Nuclear Information System (INIS)

    Goodzeit, C.L.; Anerella, M.D.; Ganetis, G.L.

    1988-01-01

    An improved method has been developed for the measurement of internal forces in superconducting accelerator magnets, in particular the compressive stresses in coils and the end restraint forces on the coils. The transducers have been designed to provide improved sensitivity to purely mechanical strain by using bending mode deflections for sensing the applied loads. Strain gauge resistance measurements are made with a new system that eliminates sources of errors due to spurious resistance changes in interconnecting wiring and solder joints. The design of the transducers and their measurement system is presented along with a discussion of the method of compensation for thermal and magnetic effects, methods of calibration with typical calibration data, and measured effect in actual magnets of the thermal stress changes from cooldown and the Lorentz forces during magnet excitation. 13 figs., 1 tab

  11. A novel AFM based method for force measurements between individual hair strands

    International Nuclear Information System (INIS)

    Max, Eva; Haefner, Wolfgang; Wilco Bartels, Frank; Sugiharto, Albert; Wood, Claudia; Fery, Andreas

    2010-01-01

    Interactions between hairs and other natural fibers are of broad interest for both applications and fundamental understanding of biological interfaces. We present a novel method, that allows force measurements between individual hair strands. Hair fragments can be laser-cut without altering their surface chemistry. Subsequently, they are glued onto Atomic force microscopy (AFM) cantilevers. This allows carrying out measurements between the hair fragment and surface immobilized hair in a well-defined crossed-cylinder geometry. Both force-distance and friction measurements are feasible. Measurements in air with controlled humidity and in aqueous environment show clear differences which can be explained by the dominating role of capillary interactions in air. Friction is found to be anisotropic, reflecting the fine structure of hair cuticula. While the investigations are focused on the particular example of human hair, we expect that the approach can be extended to other animal/plant fibers and thus offers perspectives for broad spectrum systems.

  12. Probing surface charge potentials of clay basal planes and edges by direct force measurements.

    Science.gov (United States)

    Zhao, Hongying; Bhattacharjee, Subir; Chow, Ross; Wallace, Dean; Masliyah, Jacob H; Xu, Zhenghe

    2008-11-18

    The dispersion and gelation of clay suspensions have major impact on a number of industries, such as ceramic and composite materials processing, paper making, cement production, and consumer product formulation. To fundamentally understand controlling mechanisms of clay dispersion and gelation, it is necessary to study anisotropic surface charge properties and colloidal interactions of clay particles. In this study, a colloidal probe technique was employed to study the interaction forces between a silica probe and clay basal plane/edge surfaces. A muscovite mica was used as a representative of 2:1 phyllosilicate clay minerals. The muscovite basal plane was prepared by cleavage, while the edge surface was obtained by a microtome cutting technique. Direct force measurements demonstrated the anisotropic surface charge properties of the basal plane and edge surface. For the basal plane, the long-range forces were monotonically repulsive within pH 6-10 and the measured forces were pH-independent, thereby confirming that clay basal planes have permanent surface charge from isomorphic substitution of lattice elements. The measured interaction forces were fitted well with the classical DLVO theory. The surface potentials of muscovite basal plane derived from the measured force profiles were in good agreement with those reported in the literature. In the case of edge surfaces, the measured forces were monotonically repulsive at pH 10, decreasing with pH, and changed to be attractive at pH 5.6, strongly suggesting that the charge on the clay edge surfaces is pH-dependent. The measured force profiles could not be reasonably fitted with the classical DLVO theory, even with very small surface potential values, unless the surface roughness was considered. The surface element integration (SEI) method was used to calculate the DLVO forces to account for the surface roughness. The surface potentials of the muscovite edges were derived by fitting the measured force profiles with the

  13. Measurement of friction force between two mica surfaces with multiple beam interferometry

    Directory of Open Access Journals (Sweden)

    Jung J.C.

    2010-06-01

    Full Text Available Friction forces play a crucial role in the tribological behaviour of microcomponents and the application of MEMS products. It is necessary to develop a measurement system to understand and control the material characteristics. In this study, a microscopic measurement system based on multiple beam interferometry is developed to measure the friction force between two mica thin films. Some frictional behaviour between the two mica sheets in contact are reported. The evaluated shear strength of mica agrees well to the existing data. It is possible to use the developed system for micro-tribology study.

  14. Cellular dynamics of bovine aortic smooth muscle cells measured using MEMS force sensors

    Science.gov (United States)

    Tsukagoshi, Takuya; Nguyen, Thanh-Vinh; Hirayama Shoji, Kayoko; Takahashi, Hidetoshi; Matsumoto, Kiyoshi; Shimoyama, Isao

    2018-04-01

    Adhesive cells perceive the mechanical properties of the substrates to which they adhere, adjusting their cellular mechanical forces according to their biological characteristics. This mechanical interaction subsequently affects the growth, locomotion, and differentiation of the cell. However, little is known about the detailed mechanism that underlies this interaction between adherent cells and substrates because dynamically measuring mechanical phenomena is difficult. Here, we utilize microelectromechamical systems force sensors that can measure cellular traction forces with high temporal resolution (~2.5 µs) over long periods (~3 h). We found that the cellular dynamics reflected physical phenomena with time scales from milliseconds to hours, which contradicts the idea that cellular motion is slow. A single focal adhesion (FA) generates an average force of 7 nN, which disappears in ms via the action of trypsin-ethylenediaminetetraacetic acid. The force-changing rate obtained from our measurements suggests that the time required for an FA to decompose was nearly proportional to the force acting on the FA.

  15. Encouraging conceptual change: the use of bridging analogies in the teaching of action reaction forces and the `at rest' condition in physics

    Science.gov (United States)

    Bryce, Tom; MacMillan, Kenneth

    2005-06-01

    The qualitative study described in this paper examined the effectiveness of bridging analogies intended to bring about conceptual change as part of a constructivist approach to teaching about action reaction forces in the ‘at rest’ condition in physics. Twenty-one 15-year-old students were involved in the investigation with subgroups previously exposed to different information regarding forces, weight and the accepted cause of the reaction force, in simple physical arrangements, including objects on tables. In-depth ‘think aloud’ interviews were used to track each student’s conceptual status as they worked with bridging analogies and transcript coding was carried out using open and axial coding (as in a grounded theory methodology). The findings showed that the bridging analogies were effective in engaging students with the idea of action reaction forces; students were adept in mapping each of the analogies to the target concept and using them to generate and refine their causal theories for the reaction force. There was evidence to suggest that, for some students, bridging analogies were more effective in bringing about conceptual change than didactic teaching. Their use extends beyond illustrative purposes and supports the development of meta-cognitive skills.

  16. Measurement of reaction cross sections of {sup 129}I induced by DT neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, Daisuke; Murata, Isao; Takahashi, Akito [Osaka Univ., Suita (Japan). Faculty of Engineering

    1997-03-01

    The cross sections were measured for the {sup 129}I(n,2n){sup 128}I and {sup 129}I(n,{gamma}){sup 130}I reactions by DT neutrons, at OKTAVIAN facility of Osaka University, Japan. The foil activation method was used in the measurement. The sample was a sealed source of {sup 129}I, which was covered with a Cd foil. The irradiations were performed for 75 minutes to obtain the cross section of reaction producing {sup 128}I (T{sub 1/2}=24.99m) and 22 hours for the {sup 130}I (T{sub 1/2}=12.36h), respectively. The gamma-rays emitted from the irradiated sample were measured with a high purity Ge detector. The measured cross sections of {sup 129}I(n,2n){sup 128}I and {sup 129}I(n,{gamma}){sup 130}I reactions were 0.92{+-}0.11 barn and 0.013{+-}0.002 barn, respectively. For the {sup 129}I(n,2n){sup 128}I reaction, the evaluation of JENDL-3.2 overestimates cross section about 60% to the experimental result. However, especially for the {sup 129}I(n,{gamma}) reaction, the measured cross section may include the contribution from the neutrons in MeV region as well as epithermal ones. Also, the obtained cross section of the {sup 129}I(n,{gamma}){sup 130}I reaction was evaluated as an effective production cross section of {sup 130}I including {sup 129}I(n,{gamma}){sup 130m}I reaction. In order to remove the contribution from the epithermal and MeV region neutrons. A new method was proposed for the measurement of (n,{gamma}) reaction cross section. (author)

  17. Single molecule force measurements delineate salt, pH and surface effects on biopolymer adhesion

    International Nuclear Information System (INIS)

    Pirzer, T; Geisler, M; Hugel, T; Scheibel, T

    2009-01-01

    In this paper we probe the influence of surface properties, pH and salt on the adhesion of recombinant spider silk proteins onto solid substrates with single molecule force spectroscopy. A single engineered spider silk protein (monomeric C 16 or dimeric (QAQ) 8 NR3) is covalently bound with one end to an AFM tip, which assures long-time measurements for hours with one and the same protein. The tip with the protein is brought into contact with various substrates at various buffer conditions and then retracted to desorb the protein. We observe a linear dependence of the adhesion force on the concentration of three selected salts (NaCl, NaH 2 PO 4 and NaI) and a Hofmeister series both for anions and cations. As expected, the more hydrophobic C 16 shows a higher adhesion force than (QAQ) 8 NR3, and the adhesion force rises with the hydrophobicity of the substrate. Unexpected is the magnitude of the dependences—we never observe a change of more than 30%, suggesting a surprisingly well-regulated balance between dispersive forces, water-structure-induced forces as well as co-solute-induced forces in biopolymer adhesion

  18. Single molecule force measurements delineate salt, pH and surface effects on biopolymer adhesion

    Science.gov (United States)

    Pirzer, T.; Geisler, M.; Scheibel, T.; Hugel, T.

    2009-06-01

    In this paper we probe the influence of surface properties, pH and salt on the adhesion of recombinant spider silk proteins onto solid substrates with single molecule force spectroscopy. A single engineered spider silk protein (monomeric C16 or dimeric (QAQ)8NR3) is covalently bound with one end to an AFM tip, which assures long-time measurements for hours with one and the same protein. The tip with the protein is brought into contact with various substrates at various buffer conditions and then retracted to desorb the protein. We observe a linear dependence of the adhesion force on the concentration of three selected salts (NaCl, NaH2PO4 and NaI) and a Hofmeister series both for anions and cations. As expected, the more hydrophobic C16 shows a higher adhesion force than (QAQ)8NR3, and the adhesion force rises with the hydrophobicity of the substrate. Unexpected is the magnitude of the dependences—we never observe a change of more than 30%, suggesting a surprisingly well-regulated balance between dispersive forces, water-structure-induced forces as well as co-solute-induced forces in biopolymer adhesion.

  19. Factors affecting the transverse force measurements of an optical trap: I

    Science.gov (United States)

    Wood, Tiffany A.; Wright, Amanda; Gleeson, Helen F.; Dickenson, Mark; Mullin, Tom; Murray, Andrew

    2002-03-01

    The transverse force of an optical trap is usually measured by equating the trapping force to the viscous drag force applied to the trapped particle according to Stokes' Law. Under normal conditions, the viscous drag force on a trapped particle is proportional to the fluid velocity of the medium. In this paper we show that an increase of particle concentration within the medium affects force measurements. In order to trap the particle, 1064 nm light from a Nd:YVO4 laser was brought to a focus in a sample slide, of thickness around 380 microns, by using an inverted Zeiss microscope objective, with NA equals 1.3. The slide was filled with distilled water containing 6 micron diameter polystyrene spheres. Measurements were taken at a fluid velocity of 0.75 microns/sec, achieved by moving the sample stage with a piezo-electric transducer whilst a particle was held stationary in the trap. The laser power required to hold a sphere at different trap depths for various concentrations was measured. Significant weakening of the trap was found for concentrations >0.03% solids by weight, becoming weaker for higher trap depths. These results are explained in terms of aberrations, particle-particle interactions and distortion of the beam due to particle-light interactions.

  20. Estimation of excitation forces for wave energy converters control using pressure measurements

    Science.gov (United States)

    Abdelkhalik, O.; Zou, S.; Robinett, R.; Bacelli, G.; Wilson, D.

    2017-08-01

    Most control algorithms of wave energy converters require prediction of wave elevation or excitation force for a short future horizon, to compute the control in an optimal sense. This paper presents an approach that requires the estimation of the excitation force and its derivatives at present time with no need for prediction. An extended Kalman filter is implemented to estimate the excitation force. The measurements in this approach are selected to be the pressures at discrete points on the buoy surface, in addition to the buoy heave position. The pressures on the buoy surface are more directly related to the excitation force on the buoy as opposed to wave elevation in front of the buoy. These pressure measurements are also more accurate and easier to obtain. A singular arc control is implemented to compute the steady-state control using the estimated excitation force. The estimated excitation force is expressed in the Laplace domain and substituted in the control, before the latter is transformed to the time domain. Numerical simulations are presented for a Bretschneider wave case study.

  1. Quantitative measurements of electromechanical response with a combined optical beam and interferometric atomic force microscope

    Energy Technology Data Exchange (ETDEWEB)

    Labuda, Aleksander; Proksch, Roger [Asylum Research an Oxford Instruments Company, Santa Barbara, California 93117 (United States)

    2015-06-22

    An ongoing challenge in atomic force microscope (AFM) experiments is the quantitative measurement of cantilever motion. The vast majority of AFMs use the optical beam deflection (OBD) method to infer the deflection of the cantilever. The OBD method is easy to implement, has impressive noise performance, and tends to be mechanically robust. However, it represents an indirect measurement of the cantilever displacement, since it is fundamentally an angular rather than a displacement measurement. Here, we demonstrate a metrological AFM that combines an OBD sensor with a laser Doppler vibrometer (LDV) to enable accurate measurements of the cantilever velocity and displacement. The OBD/LDV AFM allows a host of quantitative measurements to be performed, including in-situ measurements of cantilever oscillation modes in piezoresponse force microscopy. As an example application, we demonstrate how this instrument can be used for accurate quantification of piezoelectric sensitivity—a longstanding goal in the electromechanical community.

  2. Measuring minority-carrier diffusion length using a Kelvin probe force microscope

    International Nuclear Information System (INIS)

    Shikler, R.; Fried, N.; Meoded, T.; Rosenwaks, Y.

    2000-01-01

    A method based on Kelvin probe force microscopy for measuring minority-carrier diffusion length in semiconductors is described. The method is based on measuring the surface photovoltage between the tip of an atomic force microscope and the surface of an illuminated semiconductor junction. The photogenerated carriers diffuse to the junction and change the contact potential difference between the tip and the sample, as a function of the distance from the junction. The diffusion length L is then obtained by fitting the measured contact potential difference using the minority-carrier continuity equation. The method was applied to measurements of electron diffusion length in GaP pn and Schottky junctions. The measured diffusion length was found to be ∼2 μm, in good agreement with electron beam induced current measurements

  3. Sliding mode-based lateral vehicle dynamics control using tyre force measurements

    Science.gov (United States)

    Kunnappillil Madhusudhanan, Anil; Corno, Matteo; Holweg, Edward

    2015-11-01

    In this work, a lateral vehicle dynamics control based on tyre force measurements is proposed. Most of the lateral vehicle dynamics control schemes are based on yaw rate whereas tyre forces are the most important variables in vehicle dynamics as tyres are the only contact points between the vehicle and road. In the proposed method, active front steering is employed to uniformly distribute the required lateral force among the front left and right tyres. The force distribution is quantified through the tyre utilisation coefficients. In order to address the nonlinearities and uncertainties of the vehicle model, a gain scheduling sliding-mode control technique is used. In addition to stabilising the lateral dynamics, the proposed controller is able to maintain maximum lateral acceleration. The proposed method is tested and validated on a multi-body vehicle simulator.

  4. Phase-resolved fluid dynamic forces of a flapping foil energy harvester based on PIV measurements

    Science.gov (United States)

    Liburdy, James

    2017-11-01

    Two-dimensional particle image velocimetry measurements are performed in a wind tunnel to evaluate the spatial and temporal fluid dynamic forces acting on a flapping foil operating in the energy harvesting regime. Experiments are conducted at reduced frequencies (k = fc/U) of 0.05 - 0.2, pitching angle of, and heaving amplitude of A / c = 0.6. The phase-averaged pressure field is obtained by integrating the pressure Poisson equation. Fluid dynamic forces are then obtained through the integral momentum equation. Results are compared with a simple force model based on the concept of flow impulse. These results help to show the detailed force distributions, their transient nature and aide in understanding the impact of the fluid flow structures that contribute to the power production.

  5. A Simple Measure to Assess Hyperinflation and Air Trapping: 1-Forced Expiratory Volume in Three Second / Forced Vital Capacity

    Directory of Open Access Journals (Sweden)

    Sermin Börekçi

    2017-04-01

    Full Text Available Background: Several recent studies have suggested that 1 minus-forced expiratory volume expired in 3 seconds / forced vital capacity (1-FEV3/FVC may be an indicator of distal airway obstruction and a promising measure to evaluate small airways dysfunction. Aims: To investigate the associations of 1-FEV3/FVC with the spirometric measures and lung volumes that assess small airways dysfunction and reflects hyperinflation and air trapping. Study Design: Retrospective cross-sectional study. Methods: Retrospective assessment of a total of 1110 cases who underwent body plethysmographic lung volume estimations between a time span from 2005 to 2012. Patients were assigned into two groups: firstly by FEV1/FVC (FEV1/FVC <70% vs. FEV1/FVC ≥70%; secondly by FEV3/FVC < lower limits of normal (LLN (FEV3/FVC < LLN vs. FEV3/FVC ≥ LLN. Spirometric indices and lung volumes measured by whole-body plethysmography were compared in groups. Also the correlation of spirometric indices with measured lung volumes were assessed in the whole-study population and in subgroups stratified according to FEV1/FVC and FEV3/FVC. Results: Six hundred seven (54.7% were male and 503 (45.3% were female, with a mean age of 52.5±15.6 years. Mean FEV3/FVC and 1-FEV3/FVC were 87.05%, 12.95%, respectively. The mean 1-FEV3/FVC was 4.9% in the FEV1/FVC ≥70% group (n=644 vs. 24.1% in the FEV1/FVC <70% group (n=466. A positive correlation was found between 1-FEV3/FVC and residual volume (r=0.70; p<0.0001, functional residual capacity-pleth (r=0.61; p<0.0001, and total lung capacity (r=0.47; p<0.0001. 1-FEV3/FVC was negatively correlated with forced expiratory flow25-75 (r=−0.84; p<0.0001. The upper limit of 95% confidence interval for 1-FEV3/FVC was 13.7%. 1-FEV3/FVC showed significant correlations with parameters of air trapping and hyperinflation measured by whole-body plethysmography. Importantly, these correlations were higher in study participants with FEV1/FVC <70% or FEV3/FVC

  6. The measurement of low pay in the UK labour force survey

    OpenAIRE

    Skinner, Chris; Stuttard, Nigel; Beissel-Durrant, Gabriele; Jenkins, James

    2003-01-01

    Consideration of the National Minimum Wage requires estimates of the distribution of hourly pay. The UK Labour Force Survey (LFS) is a key source of such estimates. The approach most frequently adopted by researchers has been to measure hourly earnings from several questions on pay and hours. The Office for National Statistics is now applying a new approach, based on an alternative more direct measurement introduced in March 1999. These two measures do not produce identical values and this pa...

  7. Direct Measurements of Half-Cycle Reaction Heats during Atomic Layer Deposition by Calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Lownsbury, James M. [Department; Gladden, James A. [Department; Campbell, Charles T. [Department; Department; Kim, In Soo [Materials; Martinson, Alex B. F. [Materials

    2017-10-05

    We introduce a new high-temperature adsorption calorimeter that approaches the ideal limit of a heat detector whereby the signal at any time is proportional to the heat power being delivered to the sample and prove its sensitivity for measuring pulse-to-pulse heats of half-reactions during atomic layer deposition (ALD) at 400 K. The heat dynamics of amorphous Al2O3 growth via sequential self-limiting surface reaction of trimethylaluminum (TMA) and H2O is clearly resolved. Calibration enables quantitation of the exothermic TMA and H2O half-reactions with high precision, -343 kJ/mol TMA and -251 kJ/mol H2O, respectively. A time resolution better than 1 ms is demonstrated, allowing for the deconvolution of at least two distinct surface reactions during TMA microdosing. It is further demonstrated that this method can provide the heat of reaction versus extent of reaction during each precursors half-reaction, thus providing even richer mechanistic information on the surface processes involved. The broad applicability of this novel calorimeter is demonstrated through excellent signal-to-noise ratios of less exothermic ALD half-reactions to produce TiO2 and MnO.

  8. Measurement of pull-off force on imprinted nanopatterns in an inert liquid

    International Nuclear Information System (INIS)

    Kim, Jae Kwan; Lee, Dong Eon; Lee, Woo Il; Suh, Kahp Y

    2010-01-01

    We report on the measurement of the pull-off force on nanoscale patterns that are formed by thermal nanoimprint lithography (t-NIL). Various patterns with feature sizes in the range of 50-900 nm were fabricated on silicon substrates using a rigiflex polymeric mold of ultraviolet curable polyurethane acrylate (PUA, Young's modulus ∼ 1 GPa) or perfluoropolyether (PFPE, Young's modulus ∼ 10.5 MPa) and a resist layer of polystyrene (PS) of three different molecular weights (M w = 18 100, 211 600 and 2043 000). The pull-off force was measured in non-polar, non-reactive perfluorodecalin (PFD) solvent between a sharp atomic force microscopy (AFM) tip and an imprinted pattern. Our experimental data demonstrated that the measured pull-off forces were in good agreement with a simple adhesion model based on Lifshitz theory. Also, the force on the pressed region (valley) is higher than that on the cavity region (hill), with the ratio (hill/valley) decreasing with the decrease of pattern size and the increase of molecular weight. The confinement effects were more pronounced for smaller patterns ( w = 211 600 and 2043 000) presumably due to sluggish movement of polymer chains into nano-cavities. Finally, the experimental observations were compared with molecular dynamic simulations based on a simplified amorphous polyethylene model.

  9. Faraday forcing of high-temperature levitated liquid metal drops for the measurement of surface tension.

    Science.gov (United States)

    Brosius, Nevin; Ward, Kevin; Matsumoto, Satoshi; SanSoucie, Michael; Narayanan, Ranga

    2018-01-01

    In this work, a method for the measurement of surface tension using continuous periodic forcing is presented. To reduce gravitational effects, samples are electrostatically levitated prior to forcing. The method, called Faraday forcing, is particularly well suited for fluids that require high temperature measurements such as liquid metals where conventional surface tension measurement methods are not possible. It offers distinct advantages over the conventional pulse-decay analysis method when the sample viscosity is high or the levitation feedback control system is noisy. In the current method, levitated drops are continuously translated about a mean position at a small, constant forcing amplitude over a range of frequencies. At a particular frequency in this range, the drop suddenly enters a state of resonance, which is confirmed by large executions of prolate/oblate deformations about the mean spherical shape. The arrival at this resonant condition is a signature that the parametric forcing frequency is equal to the drop's natural frequency, the latter being a known function of surface tension. A description of the experimental procedure is presented. A proof of concept is given using pure Zr and a Ti 39.5 Zr 39.5 Ni 21 alloy as examples. The results compare favorably with accepted literature values obtained using the pulse-decay method.

  10. Measuring lip force by oral screens Part 2: The importance of screen design, instruction and suction.

    Science.gov (United States)

    Wertsén, Madeleine; Stenberg, Manne

    2017-10-01

    The aim of this study was to find a reliable method for measuring lip force and to find the most important factors that influence the measurements in terms of magnitude and variability. The hypothesis tested was that suction is involved and thus the instruction and the design of the oral screen are of importance when measuring lip force. This is a methodological study in a healthy population. This study was conducted in a general community. The designs of the screens were soft and hard prefabricated screens and 2 semi-individually made with a tube allowing air to pass. The screens and the instructions squeeze or suck were tested on 29 healthy adults, one at a time and on 4 occasions. The test order of the screens was randomized. Data were collected during 4 consecutive days, and the procedure was repeated after 1 month. The participants were 29 healthy adult volunteers. The instruction was an important mean to distinguish between squeezing and sucking. The design of the screen affected the lip force so that it increases in relation to the projected area of the screen. A screen design with a tube allowing air to pass made it possible to avoid suction when squeezing. By measuring with and without allowing air to pass, it was possible to distinguish between suction related and not suction related lip force. The additional screen pressure when sucking was related to the ability to produce a negative intraoral pressure. In conclusion lip force increases in relation to the projected area of the screen, sucking generally increases the measured lip force and the additional screen pressure when sucking is related to the ability to produce a negative intraoral pressure.

  11. Measurement of reaction rates of interest in stellar structure and evolution

    Energy Technology Data Exchange (ETDEWEB)

    Terrasi, F; D` Onofrio, A [Dipt. di Scienze Ambientali, Seconda Univ. di Napoli, Caserta (Italy); [INFN, Napoli (Italy); Campajola, L; Imbriani, G [INFN, Napoli (Italy); [Dipt. di Scienze Fisiche, Univ. Federico II, Napoli (Italy); Gialanella, L [INFN, Napoli (Italy); [Dipt. di Scienze Fisiche, Univ. Federico II, Napoli (Italy); [Inst. fuer Experimentalphysik III, Ruhr-Univ. Bochum, Bochum (Germany); Greife, U; Rolfs, C; Strieder, F; Trautvetter, H P [Inst. fuer Experimentalphysik III, Ruhr-Univ. Bochum, Bochum (Germany); Roca, V; Romano, M [INFN, Napoli (Italy); [Dipt. di Scienze Fisiche, Univ. Federico II, Napoli (Italy); Straniero, O [Osservatorio Astronomico di Collurania, Teramo (Italy)

    1998-06-01

    Accurate determinations of reaction rates at astrophysical energies are very important in stellar structure and evolution studies. The cases of two key reactions, namely {sup 7}Be(p,{gamma}){sup 8}B and {sup 12}C({alpha},{gamma}){sup 16}O are discussed, both from the point of view of their astrophysical interest and of the experimental difficulties in the measurement of their cross section. (orig.)

  12. A resonant absorption measurement in the reaction 26Mg(p, γ)27Al

    NARCIS (Netherlands)

    Leun, C. van der; Burhoven Jaspers, N.C.

    1966-01-01

    A resonant absorption measurement at the 1966 keV proton resonance in the reaction 26Mg(p, γ)27Al leads to an absolute determination of the resonance strength, (2J+1)ΓpΓγ/Γ, of 5.6±1.8 eV. Normalization of previously published strengths of 120 resonances in the reaction 26Mg(p, γ)27Al, reduces these

  13. Measurement of the effective thermal cross section of {sup 134}Cs by triple neutron capture reaction

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Shoji; Harada, Hideo; Katoh, Toshio [Power Reactor and Nuclear Fuel Development Corp., Tokai, Ibaraki (Japan). Tokai Works; Hatsukawa, Yuichi; Shinohara, Nobuo; Hata, Kentaro; Kobayashi, Katsutoshi; Motoishi, Shoji; Tanase, Masakazu

    1998-03-01

    The effective thermal cross section ({sigma}{sub eff}) of the {sup 134}Cs(n,{gamma}){sup 135}Cs reaction was measured by the activation method and the {gamma}-ray spectroscopic method in order to obtain fundamental data for research on the transmutation of nuclear wastes. The effective thermal cross section of the reaction {sup 134}Cs(n,{gamma}){sup 135}Cs was found to be 140.6{+-}8.5 barns. (author)

  14. Measurement of the polarization of cumulative protons in γA → pX reaction

    International Nuclear Information System (INIS)

    Avakyan, R.O.; Avakyan, E.O.; Avetisyan, A.Eh.

    1985-01-01

    The polarization of cumulative protons in γA → px reaction is measured in the range of proton energy (190+270) MeV for C, Cu, Sn, Pb nuclei. The measured polarization is practically independent of the energy of protons and the atomic number of nuclei

  15. Cheap but accurate calculation of chemical reaction rate constants from ab initio data, via system-specific, black-box force fields.

    Science.gov (United States)

    Steffen, Julien; Hartke, Bernd

    2017-10-28

    Building on the recently published quantum-mechanically derived force field (QMDFF) and its empirical valence bond extension, EVB-QMDFF, it is now possible to generate a reliable potential energy surface for any given elementary reaction step in an essentially black box manner. This requires a limited and pre-defined set of reference data near the reaction path and generates an accurate approximation of the reference potential energy surface, on and off the reaction path. This intermediate representation can be used to generate reaction rate data, with far better accuracy and reliability than with traditional approaches based on transition state theory (TST) or variational extensions thereof (VTST), even if those include sophisticated tunneling corrections. However, the additional expense at the reference level remains very modest. We demonstrate all this for three arbitrarily chosen example reactions.

  16. Do runners who suffer injuries have higher vertical ground reaction forces than those who remain injury-free? A systematic review and meta-analysis

    NARCIS (Netherlands)

    van der Worp, Henk; Vrielink, Jelte W.; Bredeweg, Steef W.

    2016-01-01

    Background Vertical ground reaction force (VGRF) parameters have been implicated as a cause of several running-related injuries. However, no systematic review has examined this relationship. Aim We systematically reviewed evidence for a relation between VGRF parameters and specific running-related

  17. The Effects of Shoulder- Girdle Muscles Fatigue on Ground Reaction Force, Elbow and Shoulder Joint Angle, and Accuracy of the Athletic Performance in Handball Penalty Throws

    Directory of Open Access Journals (Sweden)

    Mona Shiravand

    2017-09-01

    Discussion: As the subjects were professional, muscle fatigue did not have a significant effect on postural control, angles and angular velocity; but did affect the reaction force and accuracy of the throws before and after fatigue, which could ultimately affect the performance of athletes and competition results.

  18. Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Titanium

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This test method covers procedures for measuring reaction rates by the activation reactions 46Ti(n,p) 46Sc + 47Ti(n, np)46Sc. Note 1—Since the cross section for the (n,np) reaction is relatively small for energies less than 12 MeV and is not easily distinguished from that of the (n,p) reaction, this test method will refer to the (n,p) reaction only. 1.2 The reaction is useful for measuring neutrons with energies above approximately 4.4 MeV and for irradiation times up to about 250 days (for longer irradiations, see Practice E 261). 1.3 With suitable techniques, fission-neutron fluence rates above 109 cm–2·s–1 can be determined. However, in the presence of a high thermal-neutron fluence rate, 46Sc depletion should be investigated. 1.4 Detailed procedures for other fast-neutron detectors are referenced in Practice E 261. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 This standard does not purport to address all...

  19. Force sensing using 3D displacement measurements in linear elastic bodies

    Science.gov (United States)

    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.

  20. Minimising the effect of nanoparticle deformation in intermittent contact amplitude modulation atomic force microscopy measurements

    International Nuclear Information System (INIS)

    Babic, Bakir; Lawn, Malcolm A.; Coleman, Victoria A.; Jämting, Åsa K.; Herrmann, Jan

    2016-01-01

    The results of systematic height measurements of polystyrene (PS) nanoparticles using intermittent contact amplitude modulation atomic force microscopy (IC-AM-AFM) are presented. The experimental findings demonstrate that PS nanoparticles deform during AFM imaging, as indicated by a reduction in the measured particle height. This deformation depends on the IC-AM-AFM imaging parameters, material composition, and dimensional properties of the nanoparticles. A model for nanoparticle deformation occurring during IC-AM-AFM imaging is developed as a function of the peak force which can be calculated for a particular set of experimental conditions. The undeformed nanoparticle height can be estimated from the model by extrapolation to zero peak force. A procedure is proposed to quantify and minimise nanoparticle deformation during IC-AM-AFM imaging, based on appropriate adjustments of the experimental control parameters.

  1. Minimising the effect of nanoparticle deformation in intermittent contact amplitude modulation atomic force microscopy measurements

    Energy Technology Data Exchange (ETDEWEB)

    Babic, Bakir, E-mail: bakir.babic@measurement.gov.au; Lawn, Malcolm A.; Coleman, Victoria A.; Jämting, Åsa K.; Herrmann, Jan [National Measurement Institute, 36 Bradfield Road, West Lindfield, New South Wales 2070 (Australia)

    2016-06-07

    The results of systematic height measurements of polystyrene (PS) nanoparticles using intermittent contact amplitude modulation atomic force microscopy (IC-AM-AFM) are presented. The experimental findings demonstrate that PS nanoparticles deform during AFM imaging, as indicated by a reduction in the measured particle height. This deformation depends on the IC-AM-AFM imaging parameters, material composition, and dimensional properties of the nanoparticles. A model for nanoparticle deformation occurring during IC-AM-AFM imaging is developed as a function of the peak force which can be calculated for a particular set of experimental conditions. The undeformed nanoparticle height can be estimated from the model by extrapolation to zero peak force. A procedure is proposed to quantify and minimise nanoparticle deformation during IC-AM-AFM imaging, based on appropriate adjustments of the experimental control parameters.

  2. Force platform measurements as predictors of falls among older people - a review.

    Science.gov (United States)

    Piirtola, Maarit; Era, Pertti

    2006-01-01

    Poor postural balance is one of the major risk factors for falling. A great number of reports have analyzed the risk factors and predictors of falls but the results have for the most part been unclear and partly contradictory. Objective data on these matters are thus urgently needed. The force platform technique has widely been used as a tool to assess balance. However, the ability of force platform measures to predict falls remains unknown. The purpose of this systematic review was to extract and critically review the findings of prospective studies where force platform measurements have been used as predictors of falls among elderly populations. The study was done as a systematic literature review. PubMed, the Cochrane Central Register of Controlled Trials, and CINAHL databases from 1950 to April 2005 were used. The review includes prospective follow-up studies using the force platform as a tool to measure postural balance. Nine original prospective studies were included in the final analyses. In five studies fall-related outcomes were associated with some force platform measures and in the remaining four studies associations were not found. For the various parameters derived on the basis of the force platform data, the mean speed of the mediolateral (ML) movement of the center of pressure (COP) during normal standing with the eyes open and closed, the mean amplitude of the ML movement of the COP with the eyes open and closed, and the root-mean-square value of the ML displacement of COP were the indicators that showed significant associations with future falls. Measures related to dynamic posturography (moving platforms) were not predictive of falls. Despite a wide search only a few prospective follow-up studies using the force platform technique to measure postural balance and a reliable registration of subsequent falls were found. The results suggest that certain aspects of force platform data may have predictive value for subsequent falls, especially various

  3. In vivo motion and force measurement of surgical needle intervention during prostate brachytherapy

    International Nuclear Information System (INIS)

    Podder, Tarun; Clark, Douglas; Sherman, Jason; Fuller, Dave; Messing, Edward; Rubens, Deborah; Strang, John; Brasacchio, Ralph; Liao, Lydia; Ng, W.-S.; Yu Yan

    2006-01-01

    In this paper, we present needle insertion forces and motion trajectories measured during actual brachytherapy needle insertion while implanting radioactive seeds in the prostate glands of 20 different patients. The needle motion was captured using ultrasound images and a 6 degree-of-freedom electromagnetic-based position sensor. Needle velocity was computed from the position information and the corresponding time stamps. From in vivo data we found the maximum needle insertion forces to be about 15.6 and 8.9 N for 17 gauge (1.47 mm) and 18 gauge (1.27 mm) needles, respectively. Part of this difference in insertion forces is due to the needle size difference (17G and 18G) and the other part is due to the difference in tissue properties that are specific to the individual patient. Some transverse forces were observed, which are attributed to several factors such as tissue heterogeneity, organ movement, human factors in surgery, and the interaction between the template and the needle. However, theses insertion forces are significantly responsible for needle deviation from the desired trajectory and target movement. Therefore, a proper selection of needle and modulated velocity (translational and rotational) may reduce the tissue deformation and target movement by reducing insertion forces and thereby improve the seed delivery accuracy. The knowledge gleaned from this study promises to be useful for not only designing mechanical/robotic systems but also developing a predictive deformation model of the prostate and real-time adaptive controlling of the needle

  4. Measurement of Vehicle-Bridge-Interaction force using dynamic tire pressure monitoring

    Science.gov (United States)

    Chen, Zhao; Xie, Zhipeng; Zhang, Jian

    2018-05-01

    The Vehicle-Bridge-Interaction (VBI) force, i.e., the normal contact force of a tire, is a key component in the VBI mechanism. The VBI force measurement can facilitate experimental studies of the VBI as well as input-output bridge structural identification. This paper introduces an innovative method for calculating the interaction force by using dynamic tire pressure monitoring. The core idea of the proposed method combines the ideal gas law and a basic force model to build a relationship between the tire pressure and the VBI force. Then, unknown model parameters are identified by the Extended Kalman Filter using calibration data. A signal filter based on the wavelet analysis is applied to preprocess the effect that the tire rotation has on the pressure data. Two laboratory tests were conducted to check the proposed method's validity. The effects of different road irregularities, loads and forward velocities were studied. Under the current experiment setting, the proposed method was robust to different road irregularities, and the increase in load and velocity benefited the performance of the proposed method. A high-speed test further supported the use of this method in rapid bridge tests. Limitations of the derived theories and experiment were also discussed.

  5. Atomic force microscope adhesion measurements and atomistic molecular dynamics simulations at different humidities

    International Nuclear Information System (INIS)

    Seppä, Jeremias; Sairanen, Hannu; Korpelainen, Virpi; Husu, Hannu; Heinonen, Martti; Lassila, Antti; Reischl, Bernhard; Raiteri, Paolo; Rohl, Andrew L; Nordlund, Kai

    2017-01-01

    Due to their operation principle atomic force microscopes (AFMs) are sensitive to all factors affecting the detected force between the probe and the sample. Relative humidity is an important and often neglected—both in experiments and simulations—factor in the interaction force between AFM probe and sample in air. This paper describes the humidity control system designed and built for the interferometrically traceable metrology AFM (IT-MAFM) at VTT MIKES. The humidity control is based on circulating the air of the AFM enclosure via dryer and humidifier paths with adjustable flow and mixing ratio of dry and humid air. The design humidity range of the system is 20–60 %rh. Force–distance adhesion studies at humidity levels between 25 %rh and 53 %rh are presented and compared to an atomistic molecular dynamics (MD) simulation. The uncertainty level of the thermal noise method implementation used for force constant calibration of the AFM cantilevers is 10 %, being the dominant component of the interaction force measurement uncertainty. Comparing the simulation and the experiment, the primary uncertainties are related to the nominally 7 nm radius and shape of measurement probe apex, possible wear and contamination, and the atomistic simulation technique details. The interaction forces are of the same order of magnitude in simulation and measurement (5 nN). An elongation of a few nanometres of the water meniscus between probe tip and sample, before its rupture, is seen in simulation upon retraction of the tip in higher humidity. This behaviour is also supported by the presented experimental measurement data but the data is insufficient to conclusively verify the quantitative meniscus elongation. (paper)

  6. Three-Dimensional Force Measurements During Rapid Palatal Expansion in Sus scrofa

    Directory of Open Access Journals (Sweden)

    Kelly Goeckner

    2016-04-01

    Full Text Available Rapid palatal expansion is an orthodontic procedure widely used to correct the maxillary arch. However, its outcome is significantly influenced by factors that show a high degree of variability amongst patients. The traditional treatment methodology is based on an intuitive and heuristic treatment approach because the forces applied in the three dimensions are indeterminate. To enable optimal and individualized treatment, it is essential to measure the three-dimensional (3D forces and displacements created by the expander. This paper proposes a method for performing these 3D measurements using a single embedded strain sensor, combining experimental measurements of strain in the palatal expander with 3D finite element analysis (FEA. The method is demonstrated using the maxillary jaw from a freshly euthanized pig (Sus scrofa and a hyrax-design rapid palatal expander (RPE appliance with integrated strain gage. The strain gage measurements are recorded using a computer interface, following which the expansion forces and extent of expansion are estimated by FEA. A total activation of 2.0 mm results in peak total force of about 100 N—almost entirely along the direction of expansion. The results also indicate that more than 85% of the input activation is immediately transferred to the palate and/or teeth. These studies demonstrate a method for assessing and individualizing expansion magnitudes and forces during orthopedic expansion of the maxilla. This provides the basis for further development of smart orthodontic appliances that provide real-time readouts of forces and movements, which will allow personalized, optimal treatment.

  7. Development of a quartz tuning-fork-based force sensor for measurements in the tens of nanoNewton force range during nanomanipulation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Oiko, V. T. A., E-mail: oiko@ifi.unicamp.br; Rodrigues, V.; Ugarte, D. [Instituto de Física “Gleb Wataghin,” Univ. Estadual de Campinas (UNICAMP), Campinas 13083-859 (Brazil); Martins, B. V. C. [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2R3 (Canada); Silva, P. C. [Laboratório Nacional de Nanotecnologia, CNPEM, Campinas 13083-970 (Brazil)

    2014-03-15

    Understanding the mechanical properties of nanoscale systems requires new experimental and theoretical tools. In particular, force sensors compatible with nanomechanical testing experiments and with sensitivity in the nN range are required. Here, we report the development and testing of a tuning-fork-based force sensor for in situ nanomanipulation experiments inside a scanning electron microscope. The sensor uses a very simple design for the electronics and it allows the direct and quantitative force measurement in the 1–100 nN force range. The sensor response is initially calibrated against a nN range force standard, as, for example, a calibrated Atomic Force Microscopy cantilever; subsequently, applied force values can be directly derived using only the electric signals generated by the tuning fork. Using a homemade nanomanipulator, the quantitative force sensor has been used to analyze the mechanical deformation of multi-walled carbon nanotube bundles, where we analyzed forces in the 5–40 nN range, measured with an error bar of a few nN.

  8. Numerical and experimental study on vorticity measurement in liquid metal using local Lorentz force velocimetry

    Science.gov (United States)

    Hernández, Daniel; Marangoni, Rafael; Schleichert, Jan; Karcher, Christian; Fröhlich, Thomas; Wondrak, Thomas

    2018-03-01

    Local Lorentz force velocimetry (local LFV) is a contactless velocity measurement technique for liquid metals. Due to the relative movement between an electrically conductive fluid and a static applied magnetic field, eddy currents and a flow-braking Lorentz force are generated inside the metal melt. This force is proportional to the flow rate or to the local velocity, depending on the volume subset of the flow spanned by the magnetic field. By using small-size magnets, a localized magnetic field distribution is achieved allowing a local velocity assessment in the region adjacent to the wall. In the present study, we describe a numerical model of our experiments at a continuous caster model where the working fluid is GaInSn in eutectic composition. Our main goal is to demonstrate that this electromagnetic technique can be applied to measure vorticity distributions, i.e. to resolve velocity gradients as well. Our results show that by using a cross-shaped magnet system, the magnitude of the torque perpendicular to the surface of the mold significantly increases improving its measurement in a liquid metal flow. According to our numerical model, this torque correlates with the vorticity of the velocity in this direction. Before validating our numerical predictions, an electromagnetic dry calibration of the measurement system composed of a multicomponent force and torque sensor and a cross-shaped magnet was done using a rotating disk made of aluminum. The sensor is able to measure simultaneously all three components of force and torque, respectively. This calibration step cannot be avoided and it is used for an accurate definition of the center of the magnet with respect to the sensor’s coordinate system for torque measurements. Finally, we present the results of the experiments at the mini-LIMMCAST facility showing a good agreement with the numerical model.

  9. THE EFFECT OF SUBMAXIMAL INHALATION ON MEASURES DERIVED FROM FORCED EXPIRATORY SPIROMETRY

    Science.gov (United States)

    THE EFFECT OF SUBMAXIMAL INHALATION ON MEASURES DERIVED FROM FORCED EXPIRATORY SPIROMETRY. William F. McDonnell Human Studies Division, NHEERL, U.S. Environmental Protection Agency, RTP, NC 27711. Short-term exposure to ozone results in a neurally-mediated decrease in the ab...

  10. Elastic-properties measurement at high temperatures through contact resonance atomic force microscopy

    DEFF Research Database (Denmark)

    Marinello, Francesco; Pezzuolo, Andrea; Carmignato, Simone

    2015-01-01

    fast direct and non-destructive measurement of Young's modulus and related surface parameters.In this work an instrument set up for Contact Resonance Atomic Force Microscopy is proposed, where the sample with is coupled to a heating stage and a piezoelectric transducer directly vibrate the cantilever...

  11. Measurement of Levitation Forces of High-"T[subscript c] Superconductors

    Science.gov (United States)

    Becker, M.; Koblischka, M. R.; Hartmann, U.

    2010-01-01

    We show the construction of a so-called levitation balance which is capable of measuring the levitation forces between a permanent magnet and a superconducting high-T[subscript c] thin film sample. The underlying theoretical basis is discussed in detail. The experiment is performed as an introductory physics experiment for school students as well…

  12. The knee adduction moment measured with an instrumented force shoe in patients with knee osteoarthritis

    NARCIS (Netherlands)

    van den Noort, J.C.; van den Noort, Josien C.; van der Esch, Martin; Steultjens, Martijn P.M.; Dekker, Joost; Schepers, H. Martin; Veltink, Petrus H.; Harlaar, Jaap

    2012-01-01

    The external knee adduction moment (KAdM) during gait is an important parameter in patients with knee osteoarthritis (OA). KAdM measurement is currently restricted to instruments only available in gait laboratories. However, ambulatory movement analysis technology, including instrumented force shoes

  13. Surface topography characterization using an atomic force microscope mounted on a coordinate measuring machine

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo; Hansen, H.N; Kofod, N

    1999-01-01

    The paper describes the construction, testing and use of an integrated system for topographic characterization of fine surfaces on parts having relatively big dimensions. An atomic force microscope (AFM) was mounted on a manual three-coordinate measuring machine (CMM) achieving free positioning o...

  14. Force-displacement measurements of earlywood bordered pits using a mesomechanical tester

    Science.gov (United States)

    Samuel L. Zelinka; Keith J. Bourne; John C. Hermanson; Samuel V. Glass; Adriana Costa; Alex C. Wiedenhoeft

    2015-01-01

    The elastic properties of pit membranes are reported to have important implications in understanding air-seeding phenomena in gymnosperms, and pit aspiration plays a large role in wood technological applications such as wood drying and preservative treatment. Here we present force–displacement measurements for pit membranes of circular bordered pits, collected on a...

  15. Measuring q/m for Water Drops--An Introduction to the Effects of Electrical Forces

    Science.gov (United States)

    Hart, Francis X.

    1974-01-01

    Discusses an experiment which introduces students to the effects of electrical forces on the motion of macroscopic objects. Included are the proecedures of measuring the charge-to-mass ratio from deflections of charged water drops in horizontal fields and the overall charges delivered in a Faraday cup. (CC)

  16. Cross section measurements of proton capture reactions on Se isotopes relevant to the astrophysical p process

    Science.gov (United States)

    Foteinou, V.; Harissopulos, S.; Axiotis, M.; Lagoyannis, A.; Provatas, G.; Spyrou, A.; Perdikakis, G.; Zarkadas, Ch.; Demetriou, P.

    2018-03-01

    Cross sections of proton capture reactions on 74Se, 78Se, and 80Se have been measured at incident beam energies from 2 to 6 MeV, 1.7 to 3 MeV, and 1.5 to 3.5 MeV, respectively. In the case of Se,8078, cross sections were obtained from in-beam γ -angular distribution measurements, whereas for the 74Se isotope they were derived from off-beam activity measurements. The measured cross sections were compared with calculations performed with the nuclear reaction code talys (version 1.6). A good agreement between theory and experiment was found. Astrophysical S factors and reaction rates deduced from the experimental and calculated cross sections were also compared and the impact of different nuclear ingredients in the calculations on the reaction rates was investigated. It was found that, for certain combinations of nuclear input models, the reaction rates obtained at temperatures relevant to p -process nucleosynthesis differ by a factor 2 at the most, differences that are well within the acceptable deviations of calculated p -nuclei abundances and observations.

  17. Alpha-particle energy spectra measured at forward angles in heavy-ion-induced reactions

    International Nuclear Information System (INIS)

    Borcea, C.; Cierlic, E.; Kalpakchieva, R.; Oganessian, Yu.Ts.; Penionzhkevich, Yu.E.

    1980-01-01

    Energy spectra have been measured for α-particles emitted in the bombardment of 159 Tb, 181 Ta, 197 Au, and 232 Th nuclei by 20 Ne, 22 Ne, and 40 Ar projectiles. The reaction products emitted in the angular range (0+-2)deg relative to the beam direction were analyzed using a magnetic spectrometer and detected by means of a semiconductor ΔE-E telescope. It was found that in all cases the experimentally measured maximum α-particle energy almost amounts to the maximum possible value calculated from the reaction energy balance for a two-body exit channel. A correlation was found between the measured absolute cross section in different target-projectile combinations and the α-particle binding energy in the target nuclei. On the basis of the obtained results a conclusion has been drawn that the α-particles are emitted in the early stage of the reaction

  18. The reliability of linear position transducer, force plate and combined measurement of explosive power-time variables during a loaded jump squat in elite athletes.

    Science.gov (United States)

    Hansen, Keir T; Cronin, John B; Newton, Michael J

    2011-03-01

    The purpose of this study was to determine the between day reliability of power-time measures calculated with data collected using the linear position transducer or the force plate independently, or a combination of the two technologies. Twenty-five male rugby union players performed three jump squats on two occasions one week apart. Ground reaction forces were measured via a force plate and position data were collected using a linear position transducer. From these data, a number of power-time variables were calculated for each method. The force plate, linear position transducer and a combined method were all found to be a reliable means of measuring peak power (ICC = 0.87-0.95, CV = 3.4%-8.0%). The absolute consistency of power-time measures varied between methods (CV = 8.0%-53.4%). Relative consistency of power-time measures was generally comparable between methods and measures, and for many variables was at an acceptable level (ICC = 0.77-0.94). Although a number of time-dependent power variables can be reliably calculated from data acquired from the three methods investigated, the reliability of a number of these measures is below that which is acceptable for use in research and for practical applications.

  19. Trial manufacture of rotary friction tester and frictional force measurement of metals

    CERN Document Server

    Abe, T; Kanari, M; Tanzawa, S

    2002-01-01

    In the plasma confinement type fusion reactor, in-vessel structures such as a blanket module slide at the joints each other when plasma disruption occurs, and then frictional heat is generated there. Therefore, for the selection of material and the use as the design data, it is important to understand the frictional characteristics of metals and ceramic films in the vacuum. In the present study, we have manufactured a prototype of rotary friction tester and examined the performances of the tester. The frictional characteristics of metals in the room air was measured using the friction tester, and the results obtained are as follows. A drifting friction force for a constant time and a friction force during the idling were 98 mN and 225 mN, respectively. These values were sufficiently small as compared to pressing load (9.8 - 57.8 N) used in the friction test. In a friction force measurement of stainless steel, dynamic friction force obeyed Amontons' law which indicated that dynamic friction force is not depend...

  20. Interactions between Rotavirus and Suwannee River Organic Matter: Aggregation, Deposition, and Adhesion Force Measurement

    KAUST Repository

    Gutierrez, Leonardo

    2012-08-21

    Interactions between rotavirus and Suwannee River natural organic matter (NOM) were studied by time-resolved dynamic light scattering, quartz crystal microbalance, and atomic force microscopy. In NOM-containing NaCl solutions of up to 600 mM, rotavirus suspension remained stable for over 4 h. Atomic force microscopy (AFM) measurement for interaction force decay length at different ionic strengths showed that nonelectrostatic repulsive forces were mainly responsible for eliminating aggregation in NaCl solutions. Aggregation rates of rotavirus in solutions containing 20 mg C/L increased with divalent cation concentration until reaching a critical coagulation concentration of 30 mM CaCl2 or 70 mM MgCl2. Deposition kinetics of rotavirus on NOM-coated silica surface was studied using quartz crystal microbalance. Experimental attachment efficiencies for rotavirus adsorption to NOM-coated surface in MgCl2 solution were lower than in CaCl2 solution at a given divalent cation concentration. Stronger adhesion force was measured for virus-virus and virus-NOM interactions in CaCl2 solution compared to those in MgCl2 or NaCl solutions at the same ionic strength. This study suggested that divalent cation complexation with carboxylate groups in NOM and on virus surface was an important mechanism in the deposition and aggregation kinetics of rotavirus. © 2012 American Chemical Society.

  1. Near-field Light Scattering Techniques for Measuring Nanoparticle-Surface Interaction Energies and Forces.

    Science.gov (United States)

    Schein, Perry; Ashcroft, Colby K; O'Dell, Dakota; Adam, Ian S; DiPaolo, Brian; Sabharwal, Manit; Shi, Ce; Hart, Robert; Earhart, Christopher; Erickson, David

    2015-08-15

    Nanoparticles are quickly becoming commonplace in many commercial and industrial products, ranging from cosmetics to pharmaceuticals to medical diagnostics. Predicting the stability of the engineered nanoparticles within these products a priori remains an important and difficult challenge. Here we describe our techniques for measuring the mechanical interactions between nanoparticles and surfaces using near-field light scattering. Particle-surface interfacial forces are measured by optically "pushing" a particle against a reference surface and observing its motion using scattered near-field light. Unlike atomic force microscopy, this technique is not limited by thermal noise, but instead takes advantage of it. The integrated waveguide and microfluidic architecture allow for high-throughput measurements of about 1000 particles per hour. We characterize the reproducibility of and experimental uncertainty in the measurements made using the NanoTweezer surface instrument. We report surface interaction studies on gold nanoparticles with 50 nm diameters, smaller than previously reported in the literature using similar techniques.

  2. Relationship between measurements of blood oxidative metabolites and skin reaction in irradiated rats

    International Nuclear Information System (INIS)

    Kaneko, Takashi; Goto, Jun; Nomiya, Takuma; Nemoto, Kenji

    2011-01-01

    Recently, oxidative metabolites have been able to be measured by simple small device. It has been reported that the value of oxidative metabolites increases under several conditions such as hypertension, smoking, diabetes mellitus, etc. Radiation used in radiotherapy also causes free radicals and oxidative metabolites, and irradiation causes dermatitis and sometimes causes skin ulcer in the irradiated site. We analyzed the relationships between the value of oxidative metabolites and skin reactions. A certain doses of radiation were irradiated to the right thigh of rats, and oxidative metabolites of rat's blood from caudal vein were measured by d-reactive oxygen metabolites (ROMs) test using an exclusive device. Skin reactions were evaluated according to a skin-reaction grading system from the day before irradiation to day 38 after irradiation. As a results, a significant correlation was shown between irradiation dose and skin grade. And a significant correlation was also shown between the value of oxidative metabolites and irradiation dose. The increase in oxidative metabolites was seen in the Day 16 after irradiation, and that corresponded with the appearance of skin reaction. It was suggested that the value of oxidative metabolites seems to be useful for estimating degree of skin reaction and time to appear skin reaction after irradiation. (author)

  3. Measurement of activation cross sections for quasi-monoenergetic neutron induced reactions of {sup 89}Y

    Energy Technology Data Exchange (ETDEWEB)

    Zaman, Muhammad; Kim, Guinyun; Kim, Kwangsoo; Nadeem, Muhammad [Kyungpook National University, Department of Physics and Center for High Energy Physics, Daegu (Korea, Republic of); Naik, Haladhara [Kyungpook National University, Department of Physics and Center for High Energy Physics, Daegu (Korea, Republic of); Bhabha Atomic Research Centre, Radiochemistry Division, Mumbai (India); Lee, Manwoo [Dongnam Inst. of Radiological and Medical Sciences, Research Center, Busan (Korea, Republic of)

    2017-09-15

    The neutron induced cross sections of the {sup 89}Y(n, 2n){sup 88}Y, {sup 89}Y(n, 3n){sup 87}Y and {sup 89}Y(n, 4n){sup 86}Y reactions were measured in the neutron energy range of 15.2 to 37.2 MeV by using an activation and off-line γ-ray spectrometric technique. The quasi-monoenergetic neutrons used for the above reactions are based on a {sup 9}Be(p, n) reaction. Simulations of the neutron spectra from the Be target were done using the MCNPX 2.6.0 program. Theoretical calculations were performed for the {sup 89}Y(n, 2n){sup 88}Y, {sup 89}Y(n, 3n){sup 87}Y and {sup 89}Y(n, 4n){sup 86}Y reaction cross sections using nuclear model code Talys 1.8. The measured and calculated cross sections were compared with the literature data given in EXFOR and the TENDL-2015 data libraries. The present data of the {sup 89}Y(n, xn) reaction were also compared with the similar data of the {sup 89}Y(γ, xn) reaction to examine the effect of the entrance channel parameters as well as the role of projectiles and ejectiles. (orig.)

  4. 2H(p, pp) n reaction as a probe of the short-range nuclear force

    International Nuclear Information System (INIS)

    Haftel, M.I.; Petersen, E.L.; Wallace, J.M.

    1976-01-01

    We examine the feasibility of using the 2 H(p, pp) n reaction as a means of extracting information about the short-range behavior of the nuclear force not obtainable from N-N scattering experiments. To do this we use several separable potentials and examine the predicted cross section in various regions of phase space and for beam energies between 14 and 65 MeV. The questions that we address are likely to be insensitive to Coulomb effects. Both the form factor and the energy dependence of the potentials have been modified from the usual Yamaguchi form. The form of the energy dependence is chosen to obtain phase-shift equivalence for two different form factors while guaranteeing a unitary two-body scattering amplitude. The sensitivity of breakup results to the on-shell and off-shell aspects of the nuclear force is examined and discussed. Significant on-shell sensitivity occurs for breakup amplitudes in all states and for cross sections over all regions of phase space. Off-shell sensitivity appears only in the S = 1/2, L = 0 breakup amplitudes, with all S = 3/2 and all L > 0 amplitudes exhibiting negligible off-shell dependence. This result leads to only a very small (< or = 5%) off-shell sensitivity for quasifree scattering. However, cross sections far from quasifree scattering, and in particular cross sections in the final-state interaction region of phase space, exhibit as much as a 50% variation for phase-shift-equivalent potentials. This sensitivity is small at low beam energy and increases with increasing energy. The energy dependence at negative energies of one potential is also altered to adjust the triton binding energy. This enables us to compare phase-shift-equivalent potentials differing off shell but predicting the same triton binding energy. The energy dependence of this potential is somewhat unconventional. Fixing of the triton binding energy reduces the off-shell sensitivity appreciably only for E approximately-less-than 20 MeV

  5. Measuring Consumer Reactions to Sponsoring Partnerships Based upon Emotional and Attitudinal Responses

    OpenAIRE

    Riis Christensen, Sverre

    2004-01-01

    Consumers reactions from being exposed to sponsorships has primarily been measured and docu-mented applying cognitive information processing models to the phenomenon. In the paper it is argued that such effects are probably better modelled applying models of peripheral information processing to the measurements, and it is suggested that the effects can be measured on the atti-tudes-towards-the sponsor and on the emotion-towards-the sponsor levels. This type of modelling is known as the ELAM m...

  6. Reliability of the Q Force; a mobile instrument for measuring isometric quadriceps muscle strength

    OpenAIRE

    Schans, van der, C.P.; Zijlstra, W.; Regterschot, G.R.H.; Krijnen, W.P.; Douma, K.W.; Slager, G.E.C.

    2016-01-01

    BACKGROUND: The ability to generate muscle strength is a pre-requisite for all human movement. Decreased quadriceps muscle strength is frequently observed in older adults and is associated with a decreased performance and activity limitations. To quantify the quadriceps muscle strength and to monitor changes over time, instruments and procedures with a sufficient reliability are needed. The Q Force is an innovative mobile muscle strength measurement instrument suitable to measure in various d...

  7. Cross section measurement for (n,n{alpha}) reactions by 14 MeV neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Kasugai, Y.; Ikeda, Y.; Uno, Y. [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; Yamamoto, H.; Kawade, K.

    1997-03-01

    Nine (n,n{alpha}) cross sections for (n,n{alpha}) reactions induced by 13.5-14.9 MeV neutrons were measured for {sup 51}V, {sup 65}Cu, {sup 71}Ga, {sup 76}Ge, {sup 87}Rb, {sup 91}Zr, {sup 93}Nb, {sup 96}Zr and {sup 109}Ag isotopes by using Fusion Neutronics Source (FNS) at JAERI. The reactions for 91Zr and 96Zr were measured for the first time. The evaluated data of JENDL-3 and ENDF/B-VI were compared with the present data. Some of the evaluated values are much different from our data by a factor more than ten. (author)

  8. Measuring system and method of determining the Adaptive Force

    Directory of Open Access Journals (Sweden)

    Laura Schaefer

    2017-07-01

    Full Text Available The term Adaptive Force (AF describes the capability of adaptation of the nerve-muscle-system to externally applied forces during isometric and eccentric muscle action. This ability plays an important role in real life motions as well as in sports. The focus of this paper is on the specific measurement method of this neuromuscular action, which can be seen as innovative. A measuring system based on the use of compressed air was constructed and evaluated for this neuromuscular function. It depends on the physical conditions of the subject, at which force level it deviates from the quasi isometric position and merges into eccentric muscle action. The device enables – in contrast to the isokinetic systems – a measure of strength without forced motion. Evaluation of the scientific quality criteria of the devices was done by measurements regarding the intra- and interrater-, the test-retest-reliability and fatiguing measurements. Comparisons of the pneumatic device with a dynamometer were also done. Looking at the mechanical evaluation, the results show a high level of consistency (r²=0.94 to 0.96. The parallel test reliability delivers a very high and significant correlation (ρ=0.976; p=0.000. Including the biological system, the concordance of three different raters is very high (p=0.001, Cronbachs alpha α=0.987. The test retest with 4 subjects over five weeks speaks for the reliability of the device in showing no statistically significant differences. These evaluations indicate that the scientific evaluation criteria are fulfilled. The specific feature of this system is that an isometric position can be maintained while the externally impacting force rises. Moreover, the device can capture concentric, static and eccentric strength values. Fields of application are performance diagnostics in sports and medicine.

  9. Reliability of the Q Force; a mobile instrument for measuring isometric quadriceps muscle strength.

    Science.gov (United States)

    Douma, K W; Regterschot, G R H; Krijnen, W P; Slager, G E C; van der Schans, C P; Zijlstra, W

    2016-01-01

    The ability to generate muscle strength is a pre-requisite for all human movement. Decreased quadriceps muscle strength is frequently observed in older adults and is associated with a decreased performance and activity limitations. To quantify the quadriceps muscle strength and to monitor changes over time, instruments and procedures with a sufficient reliability are needed. The Q Force is an innovative mobile muscle strength measurement instrument suitable to measure in various degrees of extension. Measurements between 110 and 130° extension present the highest values and the most significant increase after training. The objective of this study is to determine the test-retest reliability of muscle strength measurements by the Q Force in older adults in 110° extension. Forty-one healthy older adults, 13 males and 28 females were included in the study. Mean (SD) age was 81.9 (4.89) years. Isometric muscle strength of the Quadriceps muscle was assessed with the Q Force at 110° of knee extension. Participants were measured at two sessions with a three to eight day interval between sessions. To determine relative reliability, the intraclass correlation coefficient (ICC) was calculated. To determine absolute reliability, Bland and Altman Limits of Agreement (LOA) were calculated and t-tests were performed. Relative reliability of the Q Force is good to excellent as all ICC coefficients are higher than 0.75. Generally a large 95 % LOA, reflecting only moderate absolute reliability, is found as exemplified for the peak torque left leg of -18.6 N to 33.8 N and the right leg of -9.2 N to 26.4 N was between 15.7 and 23.6 Newton representing 25.2 % to 39.9 % of the size of the mean. Small systematic differences in mean were found between measurement session 1 and 2. The present study shows that the Q Force has excellent relative test-retest reliability, but limited absolute test-retest reliability. Since the Q Force is relatively cheap and mobile it is suitable for

  10. Midinfrared absorption measured at a lambda/400 resolution with an atomic force microscope.

    Science.gov (United States)

    Houel, Julien; Homeyer, Estelle; Sauvage, Sébastien; Boucaud, Philippe; Dazzi, Alexandre; Prazeres, Rui; Ortéga, Jean-Michel

    2009-06-22

    Midinfrared absorption can be locally measured using a detection combining an atomic force microscope and a pulsed excitation. This is illustrated for the midinfrared bulk GaAs phonon absorption and for the midinfrared absorption of thin SiO(2) microdisks. We show that the signal given by the cantilever oscillation amplitude of the atomic force microscope follows the spectral dependence of the bulk material absorption. The absorption spatial resolution achieved with microdisks is around 50 nanometer for an optical excitation around 22 micrometer wavelength.

  11. Human occupants in low-speed frontal sled tests: effects of pre-impact bracing on chest compression, reaction forces, and subject acceleration.

    Science.gov (United States)

    Kemper, Andrew R; Beeman, Stephanie M; Madigan, Michael L; Duma, Stefan M

    2014-01-01

    The purpose of this study was to investigate the effects of pre-impact bracing on the chest compression, reaction forces, and accelerations experienced by human occupants during low-speed frontal sled tests. A total of twenty low-speed frontal sled tests, ten low severity (∼2.5g, Δv=5 kph) and ten medium severity (∼5g, Δv=10 kph), were performed on five 50th-percentile male human volunteers. Each volunteer was exposed to two impulses at each severity, one relaxed and the other braced prior to the impulse. A 59-channel chestband, aligned at the nipple line, was used to quantify the chest contour and anterior-posterior sternum deflection. Three-axis accelerometer cubes were attached to the sternum, 7th cervical vertebra, and sacrum of each subject. In addition, three linear accelerometers and a three-axis angular rate sensor were mounted to a metal mouthpiece worn by each subject. Seatbelt tension load cells were attached to the retractor, shoulder, and lap portions of the standard three-point driver-side seatbelt. In addition, multi-axis load cells were mounted to each interface between the subject and the test buck to quantify reaction forces. For relaxed tests, the higher test severity resulted in significantly larger peak values for all resultant accelerations, all belt forces, and three resultant reaction forces (right foot, seatpan, and seatback). For braced tests, the higher test severity resulted in significantly larger peak values for all resultant accelerations, and two resultant reaction forces (right foot and seatpan). Bracing did not have a significant effect on the occupant accelerations during the low severity tests, but did result in a significant decrease in peak resultant sacrum linear acceleration during the medium severity tests. Bracing was also found to significantly reduce peak shoulder and retractor belt forces for both test severities, and peak lap belt force for the medium test severity. In contrast, bracing resulted in a significant

  12. Surface tension effect on the mechanical properties of nanomaterials measured by atomic force microscopy

    Science.gov (United States)

    Cuenot, Stéphane; Frétigny, Christian; Demoustier-Champagne, Sophie; Nysten, Bernard

    2004-04-01

    The effect of reduced size on the elastic properties measured on silver and lead nanowires and on polypyrrole nanotubes with an outer diameter ranging between 30 and 250 nm is presented and discussed. Resonant-contact atomic force microscopy (AFM) is used to measure their apparent elastic modulus. The measured modulus of the nanomaterials with smaller diameters is significantly higher than that of the larger ones. The latter is comparable to the macroscopic modulus of the materials. The increase of the apparent elastic modulus for the smaller diameters is attributed to surface tension effects. The surface tension of the probed material may be experimentally determined from these AFM measurements.

  13. Effects of the positioning force of electrostatic levitators on viscosity measurements

    International Nuclear Information System (INIS)

    Ishikawa, Takehiko; Paradis, Paul-Francois; Koike, Noriyuki; Watanabe, Yuki

    2009-01-01

    Electrostatic levitators use strong electric fields to levitate and accurately position a sample against gravity. In this study, the effects of the electric field are investigated with regard to viscosity measurements conducted with the oscillating drop method. The effects of the external field on viscosity measurements are experimentally confirmed by changing the sample size. Moreover, a numerical simulation based on a simple mass-spring-damper system can reproduce the experimental observations. Based on the above results, measurement procedures are improved. These help to minimize the effect of the positioning force and to increase the accuracy of the viscosity measurements.

  14. Partnership for the Revitalization of National Wind Tunnel Force Measurement Capability

    Science.gov (United States)

    Rhew, Ray D.; Skelley, Marcus L.; Woike, Mark R.; Bader, Jon B.; Marshall, Timothy J.

    2009-01-01

    Lack of funding and lack of focus on research over the past several years, coupled with force measurement capabilities being decentralized and distributed across the National Aeronautics and Space Administration (NASA) research centers, has resulted in a significant erosion of (1) capability and infrastructure to produce and calibrate force measurement systems; (2) NASA s working knowledge of those systems; and (3) the quantity of high-quality, full-capability force measurement systems available for use in aeronautics testing. Simultaneously, and at proportional rates, the capability of industry to design, manufacture, and calibrate these test instruments has been eroding primarily because of a lack of investment by the aeronautics community. Technical expertise in this technology area is a core competency in aeronautics testing; it is highly specialized and experience-based, and it represents a niche market for only a few small precision instrument shops in the United States. With this backdrop, NASA s Aeronautics Test Program (ATP) chartered a team to examine the issues and risks associated with the problem, focusing specifically on strain- gage balances. The team partnered with the U.S. Air Force s Arnold Engineering Development Center (AEDC) to exploit their combined capabilities and take a national level government view of the problem. This paper describes the team s approach, its findings, and its recommendations, and the current status for revitalizing the government s balance capability with respect to designing, fabricating, calibrating, and using the instruments.

  15. On electrostatic and Casimir force measurements between conducting surfaces in a sphere-plane configuration

    International Nuclear Information System (INIS)

    Kim, W J; Brown-Hayes, M; Brownell, J H; Dalvit, D A R; Onofrio, R

    2009-01-01

    We report on measurements of forces acting between two conducting surfaces in a spherical-plane configuration in the 35 nm-1 μm separation range. The measurements are obtained by performing electrostatic calibrations followed by a residuals analysis after subtracting the electrostatic-dependent component. We find in all runs optimal fitting of the calibrations for exponents smaller than the one predicted by electrostatics for an ideal sphere-plane geometry. We also find that the external bias potential necessary to minimize the electrostatic contribution depends on the sphere-plane distance. In spite of these anomalies, by implementing a parametrization-dependent subtraction of the electrostatic contribution we have found evidence for short-distance attractive forces of magnitude comparable to the expected Casimir-Lifshitz force. We finally discuss the relevance of our findings in the more general context of Casimir-Lifshitz force measurements, with particular regard to the critical issues of the electrical and geometrical characterization of the involved surfaces.

  16. Analyzing power measurements for the (π+,π0) reaction on a polarized 13C target

    International Nuclear Information System (INIS)

    Goergen, J.J.

    1991-05-01

    The analyzing powers A y differential cross sections dσ/dΩ for the reaction 13 C(π + ,π 0 ) 13 N have been measured for forward scattering angles at an incident pion kinetic energy of T pi + = 163 MeV by using a transversely polarized target. Analyzing powers and reaction cross sections impose stringent constrains on nuclear reaction models and can be used to test the present understanding of nuclear structure for 1p-shell nuclei. The resulting A y are compared to the predictions of first-order Distorted Wave Impulse Approximation (DWIA) calculations, which reproduce well the differential cross sections. Although there is qualitative agreement at forward angles, the quantitative agreement is poor, especially at scattering angles larger than 50 degrees. Since the DWIA calculations do not appear to be strongly sensitive to the assumed nuclear structure model, the discrepancy in describing the analyzing powers suggests that the reaction mechanism may not yet be well understood and higher order corrections may be important. Also measured were the analyzing powers for the elementary charge exchange reaction π - bar p → π degrees n over the same angular range and at an incident pion kinetic energy of T pi - = 161 MeV. The results are compared to the most recents phase shift predictions. Within the experimental uncertainties, phase shift calculations agree with the measured A y and no changes in the πN phase shifts near the P 33 resonance are needed to describe the data

  17. Continuous optical measurement system of hemolysis during a photosensitization reaction using absorption spectrum

    Science.gov (United States)

    Hamada, R.; Ogawa, E.; Arai, T.

    2018-02-01

    To investigate hemolysis phenomena during a photosensitization reaction with the reaction condition continuously and simultaneously for a safety assessment of hemolysis side effect, we constructed an optical system to measure blood sample absorption spectrum during the reaction. Hemolysis degree might be under estimated in general evaluation methods because there is a constant oxygen pressure assumption in spite of oxygen depression take place. By investigating hemoglobin oxidation and oxygen desorption dynamics obtained from the contribution of the visible absorption spectrum and multiple regression analysis, both the hemolysis phenomena and its oxygen environment might be obtained with time. A 664 nm wavelength laser beam for the reaction excitation and 475-650 nm light beam for measuring the absorbance spectrum were arranged perpendicularly crossing. A quartz glass cuvette with 1×10 mm in dimensions for the spectrum measurement was located at this crossing point. A red blood cells suspension medium was arranged with low hematocrit containing 30 μg/ml talaporfin sodium. This medium was irradiated up to 40 J/cm2 . The met-hemoglobin, oxygenatedhemoglobin, and deoxygenated-hemoglobin concentrations were calculated by a multiple regression analysis from the measured spectra. We confirmed the met-hemoglobin concentration increased and oxygen saturation decreased with the irradiation time, which seems to indicate the hemolysis progression and oxygen consumption, respectively. By using our measuring system, the hemolysis progression seems to be obtained with oxygen environment information.

  18. A Scheme for Solving the Plane–Plane Challenge in Force Measurements at the Nanoscale

    Directory of Open Access Journals (Sweden)

    Comin Fabio

    2010-01-01

    Full Text Available Abstract Non-contact interaction between two parallel flat surfaces is a central paradigm in sciences. This situation is the starting point for a wealth of different models: the capacitor description in electrostatics, hydrodynamic flow, thermal exchange, the Casimir force, direct contact study, third body confinement such as liquids or films of soft condensed matter. The control of parallelism is so demanding that no versatile single force machine in this geometry has been proposed so far. Using a combination of nanopositioning based on inertial motors, of microcrystal shaping with a focused-ion beam (FIB and of accurate in situ and real-time control of surface parallelism with X-ray diffraction, we propose here a “gedanken” surface-force machine that should enable one to measure interactions between movable surfaces separated by gaps in the micrometer and nanometer ranges.

  19. Optical Tweezers-Based Measurements of Forces and Dynamics at Microtubule Ends.

    Science.gov (United States)

    Baclayon, Marian; Kalisch, Svenja-Marei; Hendel, Ed; Laan, Liedewij; Husson, Julien; Munteanu, E Laura; Dogterom, Marileen

    2017-01-01

    Microtubules are dynamic cytoskeletal polymers that polymerize and depolymerize while interacting with different proteins and structures within the cell. The highly regulated dynamic properties as well as the pushing and pulling forces generated by dynamic microtubule ends play important roles in processes such as in cell division. For instance, microtubule end-binding proteins are known to affect dramatically the dynamic properties of microtubules, and cortical dyneins are known to mediate pulling forces on microtubule ends. We discuss in this chapter our efforts to reconstitute these systems in vitro and mimic their interactions with structures within the cell using micro-fabricated barriers. Using an optical tweezers setup, we investigate the dynamics and forces of microtubules growing against functionalized barriers in the absence and presence of end-binding proteins and barrier-attached motor proteins. This setup allows high-speed as well as nanometer and piconewton resolution measurements on dynamic microtubules.

  20. Fractal based complexity measure and variation in force during sustained isometric muscle contraction: effect of aging.

    Science.gov (United States)

    Arjunan, Sridhar P; Kumar, Dinesh K; Bastos, Teodiano

    2012-01-01

    This study has investigated the effect of age on the fractal based complexity measure of muscle activity and variance in the force of isometric muscle contraction. Surface electromyogram (sEMG) and force of muscle contraction were recorded from 40 healthy subjects categorized into: Group 1: Young - age range 20-30; 10 Males and 10 Females, Group 2: Old - age range 55-70; 10 Males and 10 Females during isometric exercise at Maximum Voluntary contraction (MVC). The results show that there is a reduction in the complexity of surface electromyogram (sEMG) associated with aging. The results demonstrate that there is an increase in the coefficient of variance (CoV) of the force of muscle contraction and a decrease in complexity of sEMG for the Old age group when compared with the Young age group.

  1. Post-tensioning tendon force loss detection using low power pulsed eddy current measurement

    Science.gov (United States)

    Kim, Ji-Min; Lee, Jun; Sohn, Hoon

    2018-04-01

    In the field of bridge engineering, pre-fabrication of a bridge member and its construction in site have been issued and studied, which achieves improved quality and rapid construction. For integration of those pre-fabricated segments into a structural member (i.e., a concrete slab, girder and pier), post-tensioning (PT) technique is adopted utilizing a high-strength steel tendon, and an effective investigation of the remaining PT tendon force is essential to assure an overall structural integrity. This study proposes a pulsed eddy current based tendon force loss detection system. A compact eddy current sensor is designed to be installed on the surface of an anchor holding a steel PT tendon. The intensity of the induced eddy current varies with PT tendon force alteration due to the magnetostriction effect of a ferromagnetic material. The advantages of the proposed system are as follows: (1) low power consumption, (2) rapid inspection, and (3) simple installation. Its performance was validated experimentally in a full-scale lab test of a 3.3-m long, 15.2-mm diameter mono-tendon that was tensioned using a universal testing machine. Tendon force was controlled from 20 to 180 kN with 20 kN interval, and eddy current responses were measured and analyzed at each force condition. The proposed damage index and the amount of force loss of PT tendon were monotonically related, and an excessive loss as much as 30 % of an initially-introduced tendon force was successfully predicted.

  2. Understanding and Improvement of an Experiment Measuring Chemical Reaction Rates by Monitoring Volume Change of a Gas: On the Reaction between HCl(aq) and Mg(s)

    International Nuclear Information System (INIS)

    Bang, Jeong Ah; Yoon, Hee Sook; Jeong, Dae Hong; Choi, Won Ho

    2006-01-01

    In this study we analyzed and improved an experiment measuring chemical reaction rates introduced in the high school science textbooks through an understanding of the phenomena observed in carrying out the experiment. For this purpose, the contents of textbooks related to the experiment were analyzed, and the problems observed in carrying out the experiment were addressed through experimental analysis. When the experiment was carried out by the method of aquatic transposition presented in textbooks, the observed volume change of H 2 gas was delayed and chemical reaction rate was increased in the early stage of reaction period. To resolve these problems, an improved method for measuring the reaction rates was suggested. In the improved experiment the reaction rate was measured to be constant on time, which was interpreted in terms of the concentration of H + and the surface area of magnesium

  3. A force measurement system based on an electrostatic sensing and actuating technique for calibrating force in a micronewton range with a resolution of nanonewton scale

    International Nuclear Information System (INIS)

    Chen, Sheng-Jui; Pan, Sheau-Shi

    2011-01-01

    This paper introduces a force measurement system recently established at the Center for Measurement Standards, Industrial Technology Research Institute for calibrating forces in a micronewton range with a resolution of a few nanonewtons. The force balance consists of a monolithic flexure stage and a specially made capacitor for electrostatic sensing and actuating. The capacitor is formed by three electrodes which can be utilized as a capacitive position sensor and an electrostatic force actuator at the same time. Force balance control is implemented with a digital controller by which the signal of the stage deflection is acquired, filtered and fed back to the electrostatic force driver to bring the flexure stage to the null position. The detailed description of the apparatus including the design of a monolithic flexure stage, principle of capacitive position sensing/electrostatic actuation and the force balance control is given in the paper. Finally, we present the results of electrostatic force calibration and the weighing of a 1 mg wire weight

  4. Ground Reaction Force and Mechanical Differences Between the Interim Resistive Exercise Device (iRED) and Smith Machine While Performing a Squat

    Science.gov (United States)

    Amonette, William E.; Bentley, Jason R.; Lee, Stuart M. C.; Loehr, James A.; Schneider, Suzanne

    2004-01-01

    Musculoskeletal unloading in microgravity has been shown to induce losses in bone mineral density, muscle cross-sectional area, and muscle strength. Currently, an Interim Resistive Exercise Device (iRED) is being flown on board the ISS to help counteract these losses. Free weight training has shown successful positive musculoskeletal adaptations. In biomechanical research, ground reaction forces (GRF) trajectories are used to define differences between exercise devices. The purpose of this evaluation is to quantify the differences in GRF between the iRED and free weight exercise performed on a Smith machine during a squat. Due to the differences in resistance properties, inertial loading and load application to the body between the two devices, we hypothesize that subjects using iRED will produce GRF that are significantly different from the Smith machine. There will be differences in bar/harness range of motion and the time when peak GRF occurred in the ROMbar. Three male subjects performed three sets of ten squats on the iRED and on the Smith Machine on two separate days at a 2-second cadence. Statistically significant differences were found between the two devices in all measured GRF variables. Average Fz and Fx during the Smith machine squat were significantly higher than iRED. Average Fy (16.82 plus or minus.23; p less than .043) was significantly lower during the Smith machine squat. The mean descent/ascent ratio of the magnitude of the resultant force vector of all three axes for the Smith machine and iRED was 0.95 and 0.72, respectively. Also, the point at which maximum Fz occurred in the range of motion (Dzpeak) was at different locations with the two devices.

  5. Correlation of prostaglandin E2 concentrations in synovial fluid with ground reaction forces and clinical variables for pain or inflammation in dogs with osteoarthritis induced by transection of the cranial cruciate ligament.

    Science.gov (United States)

    Trumble, Troy N; Billinghurst, R Clark; McIlwraith, C Wayne

    2004-09-01

    To evaluate the temporal pattern of prostaglandin (PG) E2 concentrations in synovial fluid after transection of the cranial cruciate ligament (CCL) in dogs and to correlate PGE2 concentrations with ground reaction forces and subjective clinical variables for lameness or pain. 19 purpose-bred adult male Walker Hounds. Force plate measurements, subjective clinical analysis of pain or lameness, and samples of synovial fluid were obtained before (baseline) and at various time points after arthroscopic transection of the right CCL. Concentrations of PGE2 were measured in synovial fluid samples, and the PGE2 concentrations were correlated with ground reaction forces and clinical variables. The PGE2 concentration increased significantly above the baseline value throughout the entire study, peaking 14 days after transection. Peak vertical force and vertical impulse significantly decreased by day 14 after transection, followed by an increase over time without returning to baseline values. All clinical variables (eg, lameness, degree of weight bearing, joint extension, cumulative pain score, effusion score, and total protein content of synovial fluid, except for WBC count in synovial fluid) increased significantly above baseline values. Significant negative correlations were detected between PGE2 concentrations and peak vertical force (r, -0.5720) and vertical impulse (r, -0.4618), and significant positive correlations were detected between PGE2 concentrations and the subjective lameness score (r, 0.5016) and effusion score (r, 0.6817). Assessment of the acute inflammatory process by measurement of PGE2 concentrations in synovial fluid may be correlated with the amount of pain or lameness in dogs.

  6. Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Aluminum

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This test method covers procedures measuring reaction rates by the activation reaction 27Al(n,α)24Na. 1.2 This activation reaction is useful for measuring neutrons with energies above approximately 6.5 MeV and for irradiation times up to about 2 days (for longer irradiations, see Practice E261). 1.3 With suitable techniques, fission-neutron fluence rates above 106 cm−2·s−1 can be determined. 1.4 Detailed procedures for other fast neutron detectors are referenced in Practice E261. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  7. Light elements burning reaction rates at stellar temperatures as deduced by the Trojan Horse measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lamia, L. [Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Catania (Italy); Spitaleri, C. [Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Catania, Italy and INFN-Laboratori Nazionali del Sud, Catania (Italy); La Cognata, M.; Palmerini, S.; Sergi, M. L. [INFN-Laboratori Nazionali del Sud, Catania (Italy); Puglia, S. M. R. [INFN-Laboratori Nazionali del Sud, Catania, Italy and Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Catania (Italy)

    2015-02-24

    Experimental nuclear astrophysics aims at determining the reaction rates for astrophysically relevant reactions at their Gamow energies. For charged-particle induced reactions, the access to these energies is usually hindered, in direct measurements, by the presence of the Coulomb barrier between the interacting particles or by electron screening effects, which make hard the determination of the bare-nucleus S(E)-factor of interest for astrophysical codes. The use of the Trojan Horse Method (THM) appears as one of the most suitable tools for investigating nuclear processes of interest for astrophysics. Here, in view of the recent TH measurements, the main destruction channels for deuterium ({sup 2}H), for the two lithium {sup 6,7}Li isotopes, for the {sup 9}Be and the one for the two boron {sup 10,11}B isotopes will be discussed.

  8. Rate Coefficient Measurements of the Reaction CH3 + O2 = CH3O + O

    Science.gov (United States)

    Hwang, S. M.; Ryu, Si-Ok; DeWitt, K. J.; Rabinowitz, M. J.

    1999-01-01

    Rate coefficients for the reaction CH3 + O2 = CH3O + O were measured behind reflected shock waves in a series of lean CH4-O2-Ar mixtures using hydroxyl and methyl radical diagnostics. The rate coefficients are well represented by an Arrhenius expression given as k = (1.60(sup +0.67, sub -0.47 ) x 10(exp 13) e(-15813 +/- 587 K/T)/cubic cm.mol.s. This expression, which is valid in the temperature range 1575-1822 K, supports the downward trend in the rate coefficients that has been reported in recent determinations. All measurements to date, including the present study, have been to some extent affected by secondary reactions. The complications due to secondary reactions, choice of thermochemical data, and shock-boundary layer interactions that affect the determination of the rate coefficients are examined.

  9. Rate Coefficient Measurements of the Reaction CH3+O2+CH3O+O

    Science.gov (United States)

    Hwang, S. M.; Ryu, Si-Ok; DeWitt, K. J.; Rabinowitz, M. J.

    1999-01-01

    Rate coefficients for the reaction CH3 + O2 = CH3O + O were measured behind reflected shock waves in a series of lean CH4-O2-Ar mixtures using hydroxyl and methyl radical diagnostics. The rate coefficients are well represented by an Arrhenius expression given as k = (1.60(sup +0.67, -0.47)) X 10(exp 13) exp(- 15813 +/- 587 K/T)cc/mol s. This expression, which is valid in the temperature range 1575-1822 K, supports the downward trend in the rate coefficients that has been reported in recent determinations. All measurements to date, including the present study, have been to some extent affected by secondary reactions. The complications due to secondary reactions, choice of thermochemical data, and shock-boundary layer interactions that affect the determination of the rate coefficients are examined.

  10. Atomic force microscopy imaging to measure precipitate volume fraction in nickel-based superalloys

    International Nuclear Information System (INIS)

    Bourhettar, A.; Troyon, M.; Hazotte, A.

    1995-01-01

    In nickel-based superalloys, quantitative analysis of scanning electron microscopy images fails in providing accurate microstructural data, whereas more efficient techniques are very time-consuming. As an alternative approach, the authors propose to perform quantitative analysis of atomic force microscopy images of polished/etched surfaces (quantitative microprofilometry). This permits the measurement of microstructural parameters and the depth of etching, which is the main source of measurement bias. Thus, nonbiased estimations can be obtained by extrapolation of the measurements up to zero etching depth. In this article, the authors used this approach to estimate the volume fraction of γ' precipitates in a nickel-based superalloy single crystal. Atomic force microscopy images of samples etched for different times show definition, homogeneity, and contrast high enough to perform image analysis. The result after extrapolation is in very good agreement with volume fraction values available from published reports

  11. Measurements of stiff-material compliance on the nanoscale using ultrasonic force microscopy

    Science.gov (United States)

    Dinelli, F.; Biswas, S. K.; Briggs, G. A. D.; Kolosov, O. V.

    2000-05-01

    Ultrasonic force microscopy (UFM) was introduced to probe nanoscale mechanical properties of stiff materials. This was achieved by vibrating the sample far above the first resonance of the probing atomic force microscope cantilever where the cantilever becomes dynamically rigid. By operating UFM at different set force values, it is possible to directly measure the absolute values of the tip-surface contact stiffness. From this an evaluation of surface elastic properties can be carried out assuming a suitable solid-solid contact model. In this paper we present curves of stiffness as a function of the normal load in the range of 0-300 nN. The dependence of stiffness on the relative humidity has also been investigated. Materials with different elastic constants (such as sapphire lithium fluoride, and silicon) have been successfully differentiated. Continuum mechanics models cannot however explain the dependence of stiffness on the normal force and on the relative humidity. In this high-frequency regime, it is likely that viscous forces might play an important role modifying the tip-surface interaction. Plastic deformation might also occur due to the high strain rates applied when ultrasonically vibrating the sample. Another possible cause of these discrepancies might be the presence of water in between the two bodies in contact organizing in a solidlike way and partially sustaining the load.

  12. Atomic force microscopy measurements of bacterial adhesion and biofilm formation onto clay-sized particles

    Science.gov (United States)

    Huang, Qiaoyun; Wu, Huayong; Cai, Peng; Fein, Jeremy B.; Chen, Wenli

    2015-01-01

    Bacterial adhesion onto mineral surfaces and subsequent biofilm formation play key roles in aggregate stability, mineral weathering, and the fate of contaminants in soils. However, the mechanisms of bacteria-mineral interactions are not fully understood. Atomic force microscopy (AFM) was used to determine the adhesion forces between bacteria and goethite in water and to gain insight into the nanoscale surface morphology of the bacteria-mineral aggregates and biofilms formed on clay-sized minerals. This study yields direct evidence of a range of different association mechanisms between bacteria and minerals. All strains studied adhered predominantly to the edge surfaces of kaolinite rather than to the basal surfaces. Bacteria rarely formed aggregates with montmorillonite, but were more tightly adsorbed onto goethite surfaces. This study reports the first measured interaction force between bacteria and a clay surface, and the approach curves exhibited jump-in events with attractive forces of 97 ± 34 pN between E. coli and goethite. Bond strengthening between them occurred within 4 s to the maximum adhesion forces and energies of −3.0 ± 0.4 nN and −330 ± 43 aJ (10−18 J), respectively. Under the conditions studied, bacteria tended to form more extensive biofilms on minerals under low rather than high nutrient conditions. PMID:26585552

  13. A quadruple-scanning-probe force microscope for electrical property measurements of microscopic materials

    International Nuclear Information System (INIS)

    Higuchi, Seiji; Kubo, Osamu; Kuramochi, Hiromi; Aono, Masakazu; Nakayama, Tomonobu

    2011-01-01

    Four-terminal electrical measurement is realized on a microscopic structure in air, without a lithographic process, using a home-built quadruple-scanning-probe force microscope (QSPFM). The QSPFM has four probes whose positions are individually controlled by obtaining images of a sample in the manner of atomic force microscopy (AFM), and uses the probes as contacting electrodes for electrical measurements. A specially arranged tuning fork probe (TFP) is used as a self-detection force sensor to operate each probe in a frequency modulation AFM mode, resulting in simultaneous imaging of the same microscopic feature on an insulator using the four TFPs. Four-terminal electrical measurement is then demonstrated in air by placing each probe electrode in contact with a graphene flake exfoliated on a silicon dioxide film, and the sheet resistance of the flake is measured by the van der Pauw method. The present work shows that the QSPFM has the potential to measure the intrinsic electrical properties of a wide range of microscopic materials in situ without electrode fabrication.

  14. A new type of power energy for accelerating chemical reactions: the nature of a microwave-driving force for accelerating chemical reactions.

    Science.gov (United States)

    Zhou, Jicheng; Xu, Wentao; You, Zhimin; Wang, Zhe; Luo, Yushang; Gao, Lingfei; Yin, Cheng; Peng, Renjie; Lan, Lixin

    2016-04-27

    The use of microwave (MW) irradiation to increase the rate of chemical reactions has attracted much attention recently in nearly all fields of chemistry due to substantial enhancements in reaction rates. However, the intrinsic nature of the effects of MW irradiation on chemical reactions remains unclear. Herein, the highly effective conversion of NO and decomposition of H2S via MW catalysis were investigated. The temperature was decreased by several hundred degrees centigrade. Moreover, the apparent activation energy (Ea') decreased substantially under MW irradiation. Importantly, for the first time, a model of the interactions between microwave electromagnetic waves and molecules is proposed to elucidate the intrinsic reason for the reduction in the Ea' under MW irradiation, and a formula for the quantitative estimation of the decrease in the Ea' was determined. MW irradiation energy was partially transformed to reduce the Ea', and MW irradiation is a new type of power energy for speeding up chemical reactions. The effect of MW irradiation on chemical reactions was determined. Our findings challenge both the classical view of MW irradiation as only a heating method and the controversial MW non-thermal effect and open a promising avenue for the development of novel MW catalytic reaction technology.

  15. Preliminarily measurement and analysis of sawing forces in fresh cadaver mandible using reciprocating saw for reality-based haptic feedback.

    Science.gov (United States)

    Yua, Dedong; Zhengb, Xiaohu; Chenc, Ming; Shend, Steve G F

    2012-05-01

    The aim of the study was to preliminarily measure and analyze the cutting forces in fresh Chinese cadaver mandible using a clinically widely used reciprocating saw for reality-based haptic feedback. Eight mandibles were taken from fresh Chinese cadavers, 4 females and 4 males, aged between 59 and 95 years. A set of sawing experiments, using a surgery Stryker micro-reciprocating saw and Kistler piezoelectric dynamometer, was carried out by a CNC machining center. Under different vibration frequencies of saw and feeding rates measured from orthognathic surgery, sawing forces were recorded by a signal acquisition system. Remarkably different sawing forces were measured from different cadavers. Feed and vibration frequency of the reciprocating saw could determine the cutting forces only on 1 body. To reduce the impact of bone thickness changes on the cutting force measurements, all the cutting force data should be converted to the force of unit cutting length. The vibration frequency of haptic feedback system is determined by main cutting forces. Fast Fourier transform method can be used to calculate the frequency of this system. To simulate surgery in higher fidelity, all the sawing forces from the experiment should be amended by experienced surgeons before use in virtual reality surgery simulator. Sawing force signals of different ages for force feedback were measured successfully, and more factors related to the bone mechanical properties, such as bone density, should be concerned in the future.

  16. Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Niobium

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This test method describes procedures for measuring reaction rates by the activation reaction 93Nb(n,n′)93mNb. 1.2 This activation reaction is useful for monitoring neutrons with energies above approximately 0.5 MeV and for irradiation times up to about 30 years. 1.3 With suitable techniques, fast-neutron reaction rates for neutrons with energy distribution similar to fission neutrons can be determined in fast-neutron fluences above about 1016cm−2. In the presence of high thermal-neutron fluence rates (>1012cm−2·s−1), the transmutation of 93mNb due to neutron capture should be investigated. In the presence of high-energy neutron spectra such as are associated with fusion and spallation sources, the transmutation of 93mNb by reactions such as (n,2n) may occur and should be investigated. 1.4 Procedures for other fast-neutron monitors are referenced in Practice E 261. 1.5 Fast-neutron fluence rates can be determined from the reaction rates provided that the appropriate cross section information ...

  17. Measurement of reaction heats using a polysilicon-based microcalorimetric sensor

    NARCIS (Netherlands)

    Vereshchagina, E.; Wolters, Robertus A.M.; Gardeniers, Johannes G.E.

    2011-01-01

    In this work we present a low-cost, low-power, small sample volume microcalorimetric sensor for the measurement of reaction heats. The polysilicon-based microcalorimetric sensor combines several advantages: (i) complementary metal oxide semiconductor technology (CMOS) for future integration; (ii)

  18. A method of inferring k-infinity from reaction rate measurements in thermal reactor systems

    International Nuclear Information System (INIS)

    Newmarch, D.A.

    1967-05-01

    A scheme is described for inferring a value of k-infinity from reaction rate measurements. The method is devised with the METHUSELAH group structure in mind and was developed for the analysis of S.G.H.W. reactor experiments; the underlying principles, however, are general. (author)

  19. Development of the system for excitation function automatic measurement of nuclear reactions

    International Nuclear Information System (INIS)

    Sapozhnikov, A.B.

    2004-01-01

    Full text: The resonance nuclear reaction method is applied at the tandem accelerator UKP-2-1 to determinate films thickness and obtain light element depth distribution. The system for automatic measurement of the nuclear reaction excitation curve has been developed. It allowed to obtain an excitation function of nuclear reaction using continuous changing potential of the target with energy step of 6 eV. Saw-tooth voltage with amplitude up to 6 kV from the block of scanning beam is fed to a target. The amplitude is determined by constant voltage from the scanning beam block control. Nal(Tl) detector detects gamma quanta - the products of a nuclear reaction and transforms they in voltage impulses. The impulses through the amplifier income in the single-channel analyzer which forms impulses to start the analog-to-digital converter. The value of saw-tooth voltage corresponding to the moment of gamma quantum detection is read by the analog-to-digital converter, where it is transformed to digital code and transmitted to the computer. The computer program has been developed to control the process of accumulation of excitation function. The dependence a detected γ-quanta yield from a target potential is automatically plotted by the program. This dependence corresponds to the nuclear reaction excitation function. If scanning amplitude is not enough in order to scan need depth of a sample, an operator increases energy of the proton beam changing high voltage potential of the terminal up 3 keV and measures the nuclear reaction excitation function with the new energy. This procedure can be repeated some times. After that 'sewing' of excitation functions is carried out by the program under the hypothesis that nuclear reaction yield in last points be identical

  20. Fluid-elastic force measurements acting on a tube bundle in two-phase cross flow

    International Nuclear Information System (INIS)

    Inada, Fumio; Kawamura, Koji; Yasuo, Akira

    1996-01-01

    Fluid-elastic force acting on a square tube bundle of P/D = 1.47 in air-water two-phase cross flow was measured to investigate the characteristics and to clarify whether the fluid elastic vibration characteristics could be expressed using two-phase mixture characteristics. Measured fluid elastic forces were separated into fluid-elastic force coefficients such as added mass, added stiffness, and added damping coefficient. The added damping coefficient was separated into a two-phase damping and a flow-dependent component as in previous research (Carlucci, 1981 and 1983; Pettigrew, 1994). These coefficients were nondimensionalized with two-phase mixture characteristics such as void fraction, mixture density and mixture velocity, which were obtained using the drift-flux model with consideration given to the model. The result was compared with the result obtained with the homogeneous model. It was found that fluid-elastic force coefficients could be expressed with two-phase flow mixture characteristics very well in the experimental result, and that better result can be derived using the slip model as compared to the homogeneous model. Added two-phase flow, which could be expressed as a function of void fraction, where two-phase damping was nondimensionalized with the relative velocity between the gas and liquid phases used as a reference velocity. Using these, the added stiffness coefficient and flow-dependent component of damping could be expressed very well as a function of nondimensional mixture velocity