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Sample records for ground reaction force

  1. Ambulatory Measurement of Ground Reaction Forces

    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 se

  2. Ground Reaction Forces in Alternative Footwear during Slip Events

    Harish Chander; John C. Garner; Chip Wade

    2015-01-01

    Slips, trips and falls are major causitive factors for occupational and non-occupational falls. Alternative footwear such has crocs and flip flops have been used in and around work places and communities that can be slip prone environments. The purpose of the study is to analyze the effects of alternative footwear [crocs (CC), flip-flops (FF)] and industry standard slip resistant shoes (LT) on ground reaction forces (GRFs) during slip events. Eighteen healthy male participants following a rep...

  3. Crouched posture maximizes ground reaction forces generated by muscles.

    Hoang, Hoa X; Reinbolt, Jeffrey A

    2012-07-01

    Crouch gait decreases walking efficiency due to the increased knee and hip flexion during the stance phase of gait. Crouch gait is generally considered to be disadvantageous for children with cerebral palsy; however, a crouched posture may allow biomechanical advantages that lead some children to adopt a crouch gait. To investigate one possible advantage of crouch gait, a musculoskeletal model created in OpenSim was placed in 15 different postures from upright to severe crouch during initial, middle, and final stance of the gait cycle for a total of 45 different postures. A series of optimizations was performed for each posture to maximize transverse plane ground reaction forces in the eight compass directions by modifying muscle forces acting on the model. We compared the force profile areas across all postures. Larger force profile areas were allowed by postures from mild crouch (for initial stance) to crouch (for final stance). The overall ability to generate larger ground reaction force profiles represents a mechanical advantage of a crouched posture. This increase in muscle capacity while in a crouched posture may allow a patient to generate new movements to compensate for impairments associated with cerebral palsy, such as motor control deficits. PMID:22542242

  4. Ground Reaction Forces in Alternative Footwear during Slip Events

    Harish Chander

    2015-04-01

    Full Text Available Slips, trips and falls are major causitive factors for occupational and non-occupational falls. Alternative footwear such has crocs and flip flops have been used in and around work places and communities that can be slip prone environments. The purpose of the study is to analyze the effects of alternative footwear [crocs (CC, flip-flops (FF] and industry standard slip resistant shoes (LT on ground reaction forces (GRFs during slip events. Eighteen healthy male participants following a repeated measures design for each footwear condition, were tested for heel kinematics during normal dry surface gait (NG; unexpected slip (US, alert slip (AS and expected slip (ES. A 3x4 repeated measures ANOVA was used to analyze the dependent vertical GRFs parameters (Mean Z-GRF and Peak Z-GRF at p = 0.05. Significant interactions between footwear and gait trials were found for Mean Z-GRF and significant main effect in gait trials for Peak Z-GRF were evident. On average significantly lower GRFs were seen in slip trials compared to normal gait. FF exhibited significantly lower GRFs during slip trials while LT demonstrated lower GRFs in normal gait. The reduced ground reaction forces during all slip events compared to normal gait can be attributed to the incomplete weight transfer on the slipping foot during the unexpected and alert slips and to the anticipation of the slippery environment in expected slips. Flip flops which had greater incidence of slips also demonstrated reduced GRFs compared to CC and LT during slip events, further suggesting incomplete weight transfer, while during normal gait, LT demonstrated reduced GRFs compared to alternative footwear owing to its cushioning midsole properties. The LT with lowest incidence of slips demonstrates to be the choice of footwear for maneuvering slippery flooring conditions and for reducing impact reaction forces during non-slippery flooring conditions.Keywords: Slips, Falls, Alternative Footwear, Ground Reaction

  5. Systematic review of ground reaction force measurements in cats.

    Schnabl, E; Bockstahler, B

    2015-10-01

    Although orthopaedic abnormalities in cats are frequently observed radiographically, they remain clinically underdiagnosed, and kinetic motion analysis, a fundamental aspect of orthopaedic research in dogs and horses, is not commonly performed. More information obtained with non-invasive measurement techniques to assess normal and abnormal gait in cats would provide a greater insight into their locomotion and biomechanics and improve the objective measurement of disease alterations and treatment modalities. In this systematic review, 12 previously performed studies that investigated ground reaction force measurements in cats during locomotion were evaluated. The aims of these studies, the measurement methods and equipment used, and the outcomes of parameters used to assess both sound and diseased cats are summarised and discussed. All reviewed studies used pressure sensitive walkways to gain data and all provided an acclimatisation period as a prerequisite for measurements. In sound cats during walking, the forelimb peak vertical force was greater than in the hindlimb and the peak vertical force in the hindlimb was greater in cats than in dogs. This review confirms that ground reaction forces can be used to evaluate lameness and treatment effects in the cat. PMID:26118478

  6. Does an instrumented treadmill correctly measure the ground reaction forces?

    Patrick A. Willems

    2013-11-01

    Since the 1990s, treadmills have been equipped with multi-axis force transducers to measure the three components of the ground reaction forces during walking and running. These measurements are correctly performed if the whole treadmill (including the motor is mounted on the transducers. In this case, the acceleration of the treadmill centre of mass relative to the reference frame of the laboratory is nil. The external forces exerted on one side of the treadmill are thus equal in magnitude and opposite in direction to the external forces exerted on the other side. However, uncertainty exists about the accuracy of these measures: due to friction between the belt and the tread-surface, due to the motor pulling the belt, some believe that it is not possible to correctly measure the horizontal components of the forces exerted by the feet on the belt. Here, we propose a simple model of an instrumented treadmill and we demonstrate (1 that the forces exerted by the subject moving on the upper part of the treadmill are accurately transmitted to the transducers placed under it and (2 that all internal forces – including friction – between the parts of the treadmill are cancelling each other.

  7. Computation of ground reaction force using Zero Moment Point.

    Dijkstra, Erik J; Gutierrez-Farewik, Elena M

    2015-11-01

    Motion analysis is a common clinical assessment and research tool that uses a camera system or motion sensors and force plates to collect kinematic and kinetic information of a subject performing an activity of interest. The use of force plates can be challenging and sometimes even impossible. Over the past decade, several computational methods have been developed that aim to preclude the use of force plates. Useful in particular for predictive simulations, where a new motion or change in control strategy inherently means different external contact loads. These methods, however, often depend on prior knowledge of common observed ground reaction force (GRF) patterns, are computationally expensive, or difficult to implement. In this study, we evaluated the use of the Zero Moment Point as a computationally inexpensive tool to obtain the GRFs for normal human gait. The method was applied on ten healthy subjects walking in a motion analysis laboratory and predicted GRFs are evaluated against the simultaneously measured force plate data. Apart from the antero-posterior forces, GRFs are well-predicted and errors fall within the error ranges from other published methods. Joint extension moments were underestimated at the ankle and hip but overestimated at the knee, attributable to the observed discrepancy in the predicted application points of the GRFs. The computationally inexpensive method evaluated in this study can reasonably well predict the GRFs for normal human gait without using prior knowledge of common gait kinetics. PMID:26482731

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

    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.

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

    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 te

  10. Ground reaction forces during human locomotion on railroad ballast.

    Wade, Chip; Redfern, Mark S

    2007-11-01

    Locomotion over ballast surfaces provides a unique situation for investigating the biomechanics of gait. Although much research has focused on level and sloped walking on a smooth, firm surface in order to understand the common kinematic and kinetic variables associated with human locomotion, the literature currently provides few if any discussions regarding the dynamics of locomotion on surfaces that are either rocky or uneven. The purpose of this study was to investigate a method for using force plates to measure the ground reaction forces (GRFs) during gait on ballast. Ballast is a construction aggregate of unsymmetrical rock used in industry for the purpose of forming track bed on which railway ties are laid or in yards where railroad cars are stored. It is used to facilitate the drainage of water and to create even running surfaces. To construct the experimental ballast surfaces, 31.75 mm (1 1/4 in.) marble ballast at depths of approximately 63.5 mm (2.5 in.) or 101.6 mm (4 in.) were spread over a carpeted vinyl tile walkway specially designed for gait studies. GRF magnitudes and time histories from a force plate were collected under normal smooth surface and under both ballast surface conditions for five subjects. GRF magnitudes and time histories during smooth surface walking were similar to GRF magnitudes and time histories from the two ballast surface conditions. The data presented here demonstrate the feasibility of using a force plate system to expand the scope of biomechanical analyses of locomotion on ballast surfaces. PMID:18089931

  11. The Effect of Increasing Inertia upon Vertical Ground Reaction Forces during Locomotion

    DeWitt, John K.; Hagan, R. Donald; Cromwell, Ronita L.

    2007-01-01

    The addition of inertia to exercising astronauts could increase ground reaction forces and potentially provide a greater health benefit. However, conflicting results have been reported regarding the adaptations to additional mass (inertia) without additional net weight (gravitational force) during locomotion. We examined the effect of increasing inertia while maintaining net gravitational force on vertical ground reaction forces and kinematics during walking and running. Vertical ground reaction force was measured for ten healthy adults (5 male/5 female) during walking (1.34 m/s) and running (3.13 m/s) using a force-measuring treadmill. Subjects completed locomotion at normal weight and mass, and at 10, 20, 30, and 40% of added inertial force. The added gravitational force was relieved with overhead suspension, so that the net force between the subject and treadmill at rest remained equal to 100% body weight. Peak vertical impact forces and loading rates increased with increased inertia during walking, and decreased during running. As inertia increased, peak vertical propulsive forces decreased during walking and did not change during running. Stride time increased during walking and running, and contact time increased during running. Vertical ground reaction force production and adaptations in gait kinematics were different between walking and running. The increased inertial forces were utilized independently from gravitational forces by the motor control system when determining coordination strategies.

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

    Corbee, Ronald; Hazewinkel, Herman; Doornenbal, Arie; Maas, Huub

    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

  13. Ground reaction force sensor fault detection and recovery method based on virtual force sensor for walking biped robots

    Hashlamon, Iyad; ERBATUR, Kemalettin

    2013-01-01

    This paper presents a novel method for ground force sensor faults detection and faulty signal reconstruction using Virtual force Sensor (VFS) for slow walking bipeds. The design structure of the VFS consists of two steps, the total ground reaction force (GRF) and its location estimation for each leg based on the center of mass (CoM) position, the leg kinematics, and the IMU readings is carried on in the first step. In the second step, the optimal estimation of the distributed reaction forces ...

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

    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

  15. Validation of vertical ground reaction forces on individual limbs calculated from kinematics of horse locomotion

    Bobbert, M.F.; Alvarez, C.B.; Weeren, van, Harald; Roepstorff, L.; Weishaupt, M A

    2007-01-01

    The purpose of this study was to determine whether individual limb forces could be calculated accurately from kinematics of trotting and walking horses. We collected kinematic data and measured vertical ground reaction forces on the individual limbs of seven Warmblood dressage horses, trotting at 3.4 m s(-1) and walking at 1.6 m s(-1) on a treadmill. First, using a segmental model, we calculated from kinematics the total ground reaction force vector and its moment arm relative to each of the ...

  16. RELATIONSHIPS AMONG SPRINT VELOCITIES, HORIZONTAL GROUND REACTION FORCE, AND ISOKINETIC TRUNK STRENGTH VARIABLES

    Kale Mehmet

    2013-12-01

    Full Text Available The purpose of this study was to investigate the relationships among sprint velocities, horizontal ground reaction force, and isokinetic trunk strength variables. Voluntary 19 athletes were participated to the study [age (year= 20.9±2.3, training age (month= 91.3±48.2, body height (cm= 173.1±6.5, body weight (kg= 64.7±8.4] from different sports including in explosive strength. Sprints (10m, 20m, 30m, and 40m were tested on a non-motorized treadmill. Velocities (V10m, V20m, V30m, and V40m and horizontal ground reaction forces (HGRF-10m, HGRF-20m, HGRF-30m, and HGRF-40m of the sprints were calculated. Isokinetic trunk strength criteria (flexion-extension peak torques at 3 different angular velocities (30o.s-1, 90o.s-1, and 120o.s-1 were tested. Pearson Correlation Coefficient was used for statistical analysis. Probability level was p≤0.05. All sprint velocities was correlated with all horizontal ground reaction forces (except the correlation between V10m and HGRF-20m and all isokinetic trunk flexion-extension peak torques (except the correlation between V10m and isokinetic trunk flexion peak torque at 120o.s-1. Statistically highest significant correlations have been found between V40m and all horizontal ground reaction forces and also between V40m and isokinetic trunk flexion-extension peak torques (30o.s-1, 90o.s-1, and 120o.s-1. There were significant relationships of horizontal ground reaction forces with isokinetic trunk extension-flexion peak torques at 30o.s-1, 90o.s-1, and 120o.s-1. In conclusion, isokinetic trunk flexion and extension strength values are crucial for improving sprint acceleration and horizontal component of ground reaction force.

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

    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

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

    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…

  19. Sagittal Plane Knee Biomechanics and Vertical Ground Reaction Forces Are Modified Following ACL Injury Prevention Programs

    Padua, Darin A.; DiStefano, Lindsay J.

    2009-01-01

    Context: Injuries to the anterior cruciate ligament (ACL) occur because of excessive loading on the knee. ACL injury prevention programs can influence sagittal plane ACL loading factors and vertical ground reaction force (VGRF). Objective: To determine the influence of ACL injury prevention programs on sagittal plane knee biomechanics (anterior tibial shear force, knee flexion angle/moments) and VGRF. Data Sources: The PubMed database was searched for studies published between January 1988 an...

  20. Analysis of kinematic data and determination of ground reaction force of foot in slow squat

    Zhang, Xu-Shu; Guo, Yuan; An, Mei-Wen; Chen, Wei-Yi

    2013-02-01

    In the present paper, the ground reaction force (GRF) acting on foot in slow squat was determined through a force measuring system, and at the same time, the kinematic data of human squat were obtained by analyzing the photographed image sequences. According to the height and body weight, six healthy volunteers were selected, three men in one group and the other three women in another group, and the fundamental parameters of subjects were recorded, including body weight, height and age, etc. Based on the anatomy characteristics, some markers were placed on the right side of joints. While the subject squatted at slow speed on the force platform, the ground reaction forces on the forefoot and heel for each foot were obtained through calibrated force platform. The analysis results show that the reaction force on heel is greater than that on forefoot, and double feet have nearly constant force. Moreover, from processing and analyzing the synchronously photographed image sequences in squat, the kinematic data of human squat were acquired, including mainly the curves of angle, angular velocity and angular acceleration varied with time for knee, hip and ankle joints in a sagittal plane. The obtained results can offer instructive reference for photographing and analyzing the movements of human bodies, diagnosing some diseases, and establishing in the future appropriate mathematical models for the human motion.

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

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

    2013-01-01

    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 rol...

  2. Ground Reaction Forces and Loading Rates Associated with Parkour and Traditional Drop Landing Techniques

    Damien L. Puddle; Maulder, Peter S.

    2013-01-01

    Due to the relative infancy of Parkour there is currently a lack of empirical evidence on which to base specific technique instruction upon. The purpose of this study was to compare the ground reaction forces and loading rates involved in two Parkour landing techniques encouraged by local Parkour instructors and a traditional landing technique recommended in the literature. Ten male participants performed three different drop landing techniques (Parkour precision, Parkour roll, and traditiona...

  3. GROUND REACTION FORCE DIFFERENCES BETWEEN RUNNING SHOES, RACING FLATS, AND DISTANCE SPIKES IN RUNNERS

    Suzanna Logan; Ian Hunter; J. Ty Hopkins; J.T., J. Brent Feland; Parcell, Allen C.

    2010-01-01

    Various shoes are worn by distance runners throughout a training season. This study measured the differences in ground reaction forces between running shoes, racing flats, and distance spikes in order to provide information about the potential effects of footwear on injury risk in highly competitive runners. Ten male and ten female intercollegiate distance runners ran across a force plate at 6.7 m·s-1 (for males) and 5.7 m·s-1 (for females) in each of the three types of shoes. To control for ...

  4. Ground reaction forces and loading rates associated with parkour and traditional drop landing techniques.

    Puddle, Damien L; Maulder, Peter S

    2013-01-01

    Due to the relative infancy of Parkour there is currently a lack of empirical evidence on which to base specific technique instruction upon. The purpose of this study was to compare the ground reaction forces and loading rates involved in two Parkour landing techniques encouraged by local Parkour instructors and a traditional landing technique recommended in the literature. Ten male participants performed three different drop landing techniques (Parkour precision, Parkour roll, and traditional) onto a force plate. Compared to the traditional technique the Parkour precision technique demonstrated significantly less maximal vertical landing force (38%, p Parkour roll technique compared to the traditional technique. It is unclear whether or not the Parkour precision technique produced lower landing forces and loading rates than the Parkour roll technique as no significant differences were found. The landing techniques encouraged by local Parkour instructors such as the precision and roll appear to be more appropriate for Parkour practitioners to perform than a traditional landing technique due to the lower landing forces and loading rates experienced. Key pointsParkour precision and Parkour roll landings were found to be safer than a traditional landing technique, resulting in lower maximal vertical forces, slower times to maximal vertical force and ultimately lesser loading rates.Parkour roll may be more appropriate (safer) to utilize than the Parkour precision during Parkour landing scenarios.The Parkour landing techniques investigated n this study may be beneficial for landing by non-Parkour practitioners in everyday life. PMID:24149735

  5. Sagittal plane ground reaction forces, centre of pressure and centre of mass in trotting horses.

    Hobbs, Sarah J; Clayton, Hilary M

    2013-12-01

    The aims of this study were to measure ground reaction forces (GRFs) of concurrently loaded limbs and to evaluate spatial relationships between the centre of pressure (COP) and centre of mass (COM) in trotting horses. Kinematic (120Hz) and GRF data were collected at trot from three trials of eight horses using four force plates (960 Hz). Forelimb and hind limb GRFs were measured, COP was calculated from the resultant vertical GRF vector and COM was calculated by summation of weighted segmental COMs. Peak total vertical force (19.3 ± 1.3N/kg at 45.1 ± 2.3% diagonal stance) coincided with zero total longitudinal force (45.1 ± 2.4% stance). Initially, COP position corresponded with the fore or hind hoof of the diagonal that contacted the ground earlier. During diagonal overlap, COP position reflected forelimb contribution to total vertical GRF; it maintained a fairly constant position relative to the base of support through the middle part of stance, then moved cranially in the last third of stance towards the fore hoof, which was always the last hoof to leave the ground. The COM moved forward continuously; its longitudinal velocity decreased with the net braking force in early stance and increased with the net propulsive force in late stance. The COM was caudal to the COP in early stance, coincident at 35.8 ± 4.4% stance and was maximally ahead of the COP at 67.6 ± 4.8% stance. Changes in the spatial relationship between COP and COM affect the moment arms of the forelimb and hind limb vertical GRFs and their effect in generating a pitching torque around the COM. PMID:24138935

  6. RELATIONSHIPS AMONG SPRINT VELOCITIES, HORIZONTAL GROUND REACTION FORCE, AND ISOKINETIC TRUNK STRENGTH VARIABLES

    Kale Mehmet; Kirkaya I

    2013-01-01

    The purpose of this study was to investigate the relationships among sprint velocities, horizontal ground reaction force, and isokinetic trunk strength variables. Voluntary 19 athletes were participated to the study [age (year)= 20.9±2.3, training age (month)= 91.3±48.2, body height (cm)= 173.1±6.5, body weight (kg)= 64.7±8.4] from different sports including in explosive strength. Sprints (10m, 20m, 30m, and 40m) were tested on a non-motorized treadmill. Velocities (V10m, V20m, V30m, and V40m...

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

    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.

  8. GROUND REACTION FORCE DIFFERENCES BETWEEN RUNNING SHOES, RACING FLATS, AND DISTANCE SPIKES IN RUNNERS

    Suzanna Logan

    2010-03-01

    Full Text Available Various shoes are worn by distance runners throughout a training season. This study measured the differences in ground reaction forces between running shoes, racing flats, and distance spikes in order to provide information about the potential effects of footwear on injury risk in highly competitive runners. Ten male and ten female intercollegiate distance runners ran across a force plate at 6.7 m·s-1 (for males and 5.7 m·s-1 (for females in each of the three types of shoes. To control for differences in foot strike, only subjects who exhibited a heel strike were included in the data analysis. Two repeated-measures ANOVAs with Tukey's post-hoc tests (p < 0.05 were used to detect differences in shoe types among males and females. For the males, loading rate, peak vertical impact force and peak braking forces were significantly greater in flats and spikes compared to running shoes. Vertical stiffness in spikes was also significantly greater than in running shoes. Females had significantly shorter stance times and greater maximum propulsion forces in racing flats compared to running shoes. Changing footwear between the shoes used in this study alters the loads placed on the body. Care should be taken as athletes enter different phases of training where different footwear is required. Injury risk may be increased since the body may not be accustomed to the differences in force, stance time, and vertical stiffness

  9. GROUND REACTION FORCES AND LOADING RATES ASSOCIATED WITH PARKOUR AND TRADITIONAL DROP LANDING TECHNIQUES

    Damien L. Puddle

    2013-03-01

    Full Text Available Due to the relative infancy of Parkour there is currently a lack of empirical evidence on which to base specific technique instruction upon. The purpose of this study was to compare the ground reaction forces and loading rates involved in two Parkour landing techniques encouraged by local Parkour instructors and a traditional landing technique recommended in the literature. Ten male participants performed three different drop landing techniques (Parkour precision, Parkour roll, and traditional onto a force plate. Compared to the traditional technique the Parkour precision technique demonstrated significantly less maximal vertical landing force (38%, p < 0.01, ES = 1.76 and landing loading rate (54%, p < 0.01, ES = 1.22. Similarly, less maximal vertical landing force (43%, p < 0.01, ES = 2.04 and landing loading rate (63%, p < 0.01, ES = 1.54 were observed in the Parkour roll technique compared to the traditional technique. It is unclear whether or not the Parkour precision technique produced lower landing forces and loading rates than the Parkour roll technique as no significant differences were found. The landing techniques encouraged by local Parkour instructors such as the precision and roll appear to be more appropriate for Parkour practitioners to perform than a traditional landing technique due to the lower landing forces and loading rates experienced

  10. An algorithm to decompose ground reaction forces and moments from a single force platform in walking gait.

    Villeger, David; Costes, Antony; Watier, Bruno; Moretto, Pierre

    2014-11-01

    In walking experimental conditions, subjects are sometimes unable to perform two steps on two different forceplates. This leads the authors to develop methods for discerning right and left ground reaction data while they are summed during the double support in walking. The aim of this study is to propose an adaptive transition function that considers the walking speed and ground reaction forces (GRF). A transition function is used to estimate left and right side GRF signals in double support. It includes a shape coefficient adjusted using single support GRF parameters. This shape coefficient is optimized by a non-linear least-square curve-fitting procedure to match the estimated signals with real GRF. A multiple regression is then performed to identify GRF parameters of major importance selected to compute the right and left GRF of the double support. Relative RMSE (RMSER), maximum GRF differences normalized to body mass and differences of center of pressure (CoP) are computed between real and decomposed signals. During double support, RMSER are 6%, 18%, 3.8%, 4.3%, 3%, and 12.3% for anterior force, lateral force, vertical force, frontal moment, sagittal moment and transverse moment, respectively. Maximum GRF differences normalized to body mass are lower than 1N/kg and mean CoP difference is 0.0135 m, when comparing real to decomposed signals during double support. This work shows the accuracy of an adaptive transition function to decompose GRF and moment of right and left sides. This method is especially useful to accurately discern right and left GRF data in single force platform configurations. PMID:25239287

  11. The Effect of Exertion and Sex on Vertical Ground Reaction Force Variables and Landing Mechanics.

    Bell, David R; Pennuto, Anthony P; Trigsted, Stephanie M

    2016-06-01

    Bell, DR, Pennuto, AP, and Trigsted, SM. The effect of exertion and sex on vertical ground reaction force variables and landing mechanics. J Strength Cond Res 30(6): 1661-1669, 2016-The purpose of this investigation was to determine how exertion and sex affected a variety of vertical ground reaction force (VGRF) parameters during a jump-landing task, including peak VGRF, peak VGRF asymmetry, loading rate, and loading rate asymmetry. Additionally, we wanted to determine whether landing mechanics changed after exertion as measured by the Landing Error Scoring System (LESS). Forty recreationally active participants (20 men and 20 women) completed jump landings from a 30-cm-high box onto force plates before and after repeated bouts of an exercise circuit until a specific rating of perceived exertion was achieved. Three-way (sex × time × limb) analyses of variance were used to analyze variables pre-exertion to postexertion. No significant 3-way interactions were observed for peak VGRF (p = 0.31) or loading rate (p = 0.14). Time by sex interactions were observed for peak VGRF (p = 0.02) and loading rate (p = 0.008). Post hoc analysis revealed that men increased landing force and loading rate after exertion while women did not. Landing mechanics, as assessed by total LESS score, were worse after exertion (p < 0.001) with increased frequency of errors for knee flexion <30° at initial contact, lateral trunk flexion, and not flexing the hip during landing. Women may be more resistant to exertion compared with men and use different joint controls' strategies to cope with VGRF after exertion. However, VGRF asymmetry is not affected by sex and exertion. Limiting peak VGRF and addressing landing postures, especially after exertion, should be components of injury prevention strategies. PMID:26562710

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

    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

  13. Gender Differences among Sagittal Plane Knee Kinematic and Ground Reaction Force Characteristics during a Rapid Sprint and Cut Maneuver

    James, C. Roger; Sizer, Phillip S.; Starch, David W.; Lockhart, Thurmon E.; Slauterbeck, James

    2004-01-01

    Women are more prone to anterior cruciate ligament (ACL) injury during cutting sports than men. The purpose of this study was to examine knee kinematic and ground reaction forces (GRF) differences between genders during cutting. Male and female athletes performed cutting trials while force platform and video data were recorded (180 Hz).…

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

    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 ...

  15. A ground reaction force analysis for designing a sustainable energy-harvesting stairway

    Puspitarini, Debrina; Suzianti, Amalia; Rasyid, Harun Al; Priscandy, Nabila

    2016-06-01

    There are many issues of how energy is currently generated and consumed. These include the cost of harvesting energy, the ever-growing demand for it, and the ever-decreasing reserve of current most applicable energy resources. Numerous ways to exploit new sustainable potential energy sources have been pursued, one of which is to create an energy-harvester; a device that captures free potential energy, scattered around in its environment, and transform it into another form of energy. Using NPD approach, Puspitarini, Suzianti, and Al Rasyid (2016) has developed a conceptual design of an energy-harvesting device, which includes a selection of product specification options and a gear set layout design. In this study, a mockup was built for the experiment based on those product specification options. The experiment was conducted using AMTI Force Platform, and its results were processed using Factorial Design. This effort is to test which product specification option contributes the most to Ground Reaction Force (GRF) generation. The greater the generated GRF, the greater amount of electricity produced. A theoretical calculation of electromotive force was also conducted based on the experiment result and the gear set layout design. The result of this study was later discussed and used as a basis to develop further the stairway design.

  16. Ground reaction forces on stairs: effects of stair inclination and age.

    Stacoff, Alex; Diezi, Christian; Luder, Gerhard; Stüssi, Edgar; Kramers-de Quervain, Inès A

    2005-01-01

    The goals of the study were to compare data of vertical ground reaction force (GRF) parameters during level walking, stair ascent and descent on three different stair inclinations and three different age groups. Twenty healthy subjects of three age groups (young 33.7 years; middle 63.6 years; old 76.5 years) were tested during the seven test conditions with 8-10 repetitions. Vertical forces were measured during two consecutive steps with force plates embedded in the walkway and the staircase. The results showed that during level walking the vertical GRF curves were very regular and repetitive, the trail-to-trial variability and left-right asymmetry of defined test parameters being around 2-5% and 3-5%. During stair ascent the vertical GRF force pattern was found to change slightly compared to level gait, but considerably compared to stair descent. On the steep stair the average vertical load increased up to 1.6 BW, and variability (5-10%) and asymmetry (5-15%) were increased significantly. The steep stair descent condition was found to be the most demanding test showing the largest variability and asymmetry and thus, the least stable gait pattern. Age was found to be a factor which should be considered, because the young age group walked faster and produced larger vertical GRF maxima during level walking and on stair ascent than the middle and old age group. Differences between the middle and old age group were found to be small. The present investigation is the first to provide normative data of GRF parameters on gait variability and symmetry of two consecutive steps during level gait and stair ambulation. It is the intention that the results of this study may be used as a basis for comparison with patient data. PMID:15536031

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

    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. PMID:23702045

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

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

    2016-03-01

    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. PMID:26836969

  19. Residual analysis of ground reaction forces simulation during gait using neural networks with different configurations.

    Leporace, Gustavo; Batista, Luiz Alberto; Metsavaht, Leonardo; Nadal, Jurandir

    2015-08-01

    The aim of the study was to analyze and compare the residuals obtained from ground reaction force (GRF) models developed using two different neural network configurations (one network with three outputs; and three networks with one output each), based on accelerometer data. Seventeen healthy subjects walked along a walkway, with a force plate embedded, with a three dimensional accelerometer attached to the shank. Multilayer perceptron networks (MLP) models were developed with the 3D accelerometer data as inputs to predict the GRF. The residuals of these models were evaluated graphically and numerically to verify the fitting. A visual analysis of the simulated signals suggests the model was able to adequately predict the GRF. The errors and correlations found in the MLP models for the 3D GRF is at least similar to other studies, although some of them showed higher errors. There was not difference between the two MLP configurations. However, despite the high correlation coefficient and closeness to a normal probability distribution, the residual analysis still presented a higher kurtosis and skewness, suggesting that the inclusion of other variables and the increase of the validation sample size could increase the fitting of the simulation. PMID:26736876

  20. Normalization of ground reaction forces, joint moments, and free moments in human locomotion.

    Wannop, John W; Worobets, Jay T; Stefanyshyn, Darren J

    2012-12-01

    Authors who report ground reaction force (GRF), free moment (FM), and resultant joint moments usually normalize these variables by division normalization. Normalization parameters include body weight (BW), body weight x height (BWH), and body weight x leg length (BWL). The purpose of this study was to explore the appropriateness of division normalization, power curve normalization, and offset normalization on peak GRF, FM, and resultant joint moments. Kinematic and kinetic data were collected on 98 subjects who walked at 1.2 and 1.8 m/s and ran at 3.4 and 4.0 m/s. Linear curves were best fit to the data, and regression analyses performed to test the significance of the correlations. It was found that the relationship between peak force and BW, as well as joint moments and BW, BWH, and BWL, were not always linear. After division normalization, significant correlations were still found. Power curve and offset normalization, however, were effective at normalizing all variables; therefore, when attempting to normalize GRF and joint moments, perhaps nonlinear or offset methods should be implemented. PMID:23348130

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

    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 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.

  2. Bilateral and unilateral vertical ground reaction forces and leg asymmetries in soccer players.

    Yanci, J; Camara, J

    2016-06-01

    The purposes of this study were to assess unilateral and bilateral vertical jump performance characteristics, and to compare the vertical ground reaction force characteristics of the impulse and landing phase of a vertical jump between the dominant and non-dominant leg in soccer players. The sample consisted of 20 male soccer players (22.80 ± 2.71 years, 1.88 ± 0.06 m, 76.47 ± 8.80 kg) who competed in the third division of the Spanish football league. Vertical jump performance was determined by testing the impulse and landing phase of a bilateral vertical jump, dominant leg vertical jump and non-dominant leg vertical jump. Significant differences (p < 0.05) between dominant and non-dominant legs were found in counter movement jump (CMJ) flight time (LA = -2.38%, d = 0.33), CMJ flight height (LA = -4.55%, d = 0.33) and CMJ speed take-off (LA = -2.91%, d = 0.42). No significant differences were found between the dominant and non-dominant leg in the F1 and F2 magnitudes during the landing phase, the time from the first contact of the foot with the ground to the production of F1, the time from the second contact of the foot with the ground to the production of F2, and the time to stabilization of the landing phase. Although differences were found between the dominant and non-dominant leg in the impulse phase of the jump, no significant differences were found between dominant and non-dominant legs in the landing phase of vertical jump variables. PMID:27274112

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

    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

  4. Subject recognition based on ground reaction force measurements of gait signals.

    Moustakidis, Serafeim P; Theocharis, John B; Giakas, Giannis

    2008-12-01

    An effective subject recognition approach is designed in this paper, using ground reaction force (GRF) measurements of human gait. The method is a three-stage procedure: 1) The original GRF data are translated through wavelet packet (WP) transform in the time-frequency domain. Using a fuzzy-set-based criterion, we determine an optimal WP decomposition, involving feature subspaces with distinguishing gait characteristics. 2) A feature extraction scheme is employed next for wavelet feature ranking, according to discrimination power. 3) The classification task is accomplished by means of a kernel-based support vector machine. The design parameters of the classifier are tuned through a genetic algorithm to improve recognition rates. The method is evaluated on a database comprising GRF records obtained from 40 subjects. To account for the natural variability of human gait, the experimental setup is designed, allowing different walking speeds and loading conditions. Simulation results demonstrate that high recognition rates can be achieved with moderate number of features and for different training/testing settings. Finally, the performance of our approach is favorably compared with the one obtained using other traditional classification algorithms. PMID:19022720

  5. Estimation of ground reaction force and zero moment point on a powered ankle-foot prosthesis.

    Martinez-Villalpando, Ernesto C; Herr, Hugh; Farrell, Matthew

    2007-01-01

    The ground reaction force (GRF) and the zero moment point (ZMP) are important parameters for the advancement of biomimetic control of robotic lower-limb prosthetic devices. In this document a method to estimate GRF and ZMP on a motorized ankle-foot prosthesis (MIT Powered Ankle-Foot Prosthesis) is presented. The method proposed is based on the analysis of data collected from a sensory system embedded in the prosthetic device using a custom designed wearable computing unit. In order to evaluate the performance of the estimation methods described, standing and walking clinical studies were conducted on a transtibial amputee. The results were statistically compared to standard analysis methodologies employed in a gait laboratory. The average RMS error and correlation factor were calculated for all experimental sessions. By using a static analysis procedure, the estimation of the vertical component of GRF had an averaged correlation coefficient higher than 0.94. The estimated ZMP location had a distance error of less than 1 cm, equal to 4% of the anterior-posterior foot length or 12% of the medio-lateral foot width. PMID:18003052

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

    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. PMID:16414263

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

    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…

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

    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. Vertical Ground Reaction Forces are Associated with Pain and Self-Reported Functional Status in Recreational Athletes with Patellofemoral Pain.

    de Oliveira Silva, Danilo; Briani, Ronaldo; Pazzinatto, Marcella; Ferrari, Deisi; Aragão, Fernando; de Azevedo, Fábio

    2015-12-01

    Individuals with patellofemoral pain (PFP) use different motor strategies during unipodal support in stair climbing activities, which may be assessed by vertical ground reaction force parameters. Thus, the aims of this study were to investigate possible differences in first peak, valley, second peak, and loading rate between recreational female athletes with PFP and pain-free athletes during stair climbing in order to determine the association and prediction capability between these parameters, pain level, and functional status in females with PFP. Thirty-one recreational female athletes with PFP and 31 pain-free recreational female athletes were evaluated with three-dimensional kinetics while performing stair climbing to obtain vertical ground reaction force parameters. A visual analog scale was used to evaluate the usual knee pain. The anterior knee pain scale was used to evaluate knee functional score. First peak and loading rate were associated with pain (r = .46, P = .008; r = .56, P = .001, respectively) and functional limitation (r = .31, P = .049; r = -.36, P = .032, respectively). Forced entry regression revealed the first peak was a significant predictor of pain (36.5%) and functional limitation (28.7%). Our findings suggest that rehabilitation strategies aimed at correcting altered vertical ground reaction force may improve usual knee pain level and self-reported knee function in females with PFP. PMID:26286949

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

    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.

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

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

    2016-03-01

    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. Key pointsPAS can effectively protect the ligamentous structure from spraining by providing mechanical support and cutaneous proprioceptive benefits.Using of PAS can

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

    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

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

    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. PMID:25846952

  14. Comparison of ankle kinematics and ground reaction forces between prospectively injured and uninjured collegiate cross country runners.

    Kuhman, Daniel J; Paquette, Max R; Peel, Shelby A; Melcher, Daniel A

    2016-06-01

    Biomechanical comparative studies on running-related injuries have included either currently or retrospectively injured runners. The purpose of this study was to prospectively compare ankle joint and ground reaction force variables between collegiate runners who developed injuries during the cross country season and those who did not. Running gait analyses using a motion capture system and force platform were conducted on 19 collegiate runners prior to the start of their cross country season. Ten runners sustained running-related injuries and 9 remained healthy during the course of the season. Strike index, peak loading rate of the vertical ground reaction force, dorsiflexion range of motion (ROM), eversion ROM, peak eversion angle, peak eversion velocity, and eversion duration from the start of the season were compared between injury groups. Ankle eversion ROM and peak eversion velocity were greater in uninjured runners while peak eversion angle was greater in injured runners. Greater ankle eversion ROM and eversion velocity with lower peak eversion angle may be beneficial in reducing injury risk in collegiate runners. The current data may only be applicable to collegiate cross country runners with similar training and racing schedules and threshold magnitudes of ankle kinematic variables to predict injury risk are still unknown. PMID:26827155

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

    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)

  16. Changes in ground reaction force during a rebound-jump task after hip strength training for single-sided ankle dorsiflexion restriction

    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. PMID:27065513

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

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

    Ketabi, Shahin; Kersting, Uwe G.

    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 such...

  19. Do runners who suffer injuries have higher vertical ground reaction forces than those who remain injury-free? A systematic review and meta-analysis

    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 i

  20. Do runners who suffer injuries have higher vertical ground reaction forces than those who remain injury-free? : A systematic review and meta-analysis

    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

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

    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

  2. Increasing plantarflexion angle during landing reduces vertical ground reaction forces, loading rates and the hip's contribution to support moment within participants.

    Rowley, K Michael; Richards, James G

    2015-01-01

    The ankle joint's role in shock absorption during landing has been researched in many studies, which have found that landing with higher amounts of plantarflexion (PF) results in lower peak vertical ground reaction forces and loading rates. However, there has not yet been a study that compares drop landings within participants along a quantitative continuum of PF angles. Using a custom-written real-time feedback program, participants adjusted their ankles to an instructed PF angle and dropped onto two force platforms. For increasing PF, peak ground reaction force and peak loading rate during weight acceptance decreased significantly. The hip's contribution to peak support moment decreased as PF at initial contact increased up to 30°. The ankle and knee contributions increased over this same continuum of PF angles. There appears to be no optimal PF angle based on peak ground reaction force and loading rate measurements, but there may be an optimum where joint contributions to peak support moment converge and the hip moment's contribution is minimised. PMID:25775364

  3. A comparison of lower limb EMG and ground reaction forces between barefoot and shod gait in participants with diabetic neuropathic and healthy controls

    Akashi Paula MH

    2010-02-01

    Full Text Available Abstract Background It is known that when barefoot, gait biomechanics of diabetic neuropathic patients differ from non-diabetic individuals. However, it is still unknown whether these biomechanical changes are also present during shod gait which is clinically advised for these patients. This study investigated the effect of the participants own shoes on gait biomechanics in diabetic neuropathic individuals compared to barefoot gait patterns and healthy controls. Methods Ground reaction forces and lower limb EMG activities were analyzed in 21 non-diabetic adults (50.9 ± 7.3 yr, 24.3 ± 2.6 kg/m2 and 24 diabetic neuropathic participants (55.2 ± 7.9 yr, 27.0 ± 4.4 kg/m2. EMG patterns of vastus lateralis, lateral gastrocnemius and tibialis anterior, along with the vertical and antero-posterior ground reaction forces were studied during shod and barefoot gait. Results Regardless of the disease, walking with shoes promoted an increase in the first peak vertical force and the peak horizontal propulsive force. Diabetic individuals had a delay in the lateral gastrocnemius EMG activity with no delay in the vastus lateralis. They also demonstrated a higher peak horizontal braking force walking with shoes compared to barefoot. Diabetic participants also had a smaller second peak vertical force in shod gait and a delay in the vastus lateralis EMG activity in barefoot gait compared to controls. Conclusions The change in plantar sensory information that occurs when wearing shoes revealed a different motor strategy in diabetic individuals. Walking with shoes did not attenuate vertical forces in either group. Though changes in motor strategy were apparent, the biomechanical did not support the argument that the use of shoes contributes to altered motor responses during gait.

  4. Zapateado technique as an injury risk in Mexican folkloric and Spanish dance: an analysis of execution, ground reaction force, and muscle strength.

    Echegoyen, Soledad; Aoyama, Takeshi; Rodríguez, Cristina

    2013-06-01

    Zapateado is a repetitive percussive footwork in dance. This percussive movement, and the differences in technique, may be risk factors for injury. A survey on zapateado dance students found a rate of 1.5 injuries/1,000 exposures. Knee injuries are more frequent than in Spanish dancers than folkloric dancers. The aim of this research was to study the relationship between technique and ground reaction force between zapateado on Spanish and Mexican folkloric dancers. Ten female dance students (age 22.4 ± 4 yrs), six Spanish dancers and four Mexican folkloric dancers, were considered. Each student performed zapateado with a flat foot, wearing high-heeled shoes during 5 seconds on a force platform. Videotapes were taken on a lateral plane, and knee and hip angles in each movement phase were measured with Dartfish software. Additionally, knee and ankle flexor and extensor strength was measured with a dynamometer. Ground reaction forces were lower for Spanish dancers than Mexican folkloric dancers. Spanish dancers had less knee flexion when the foot contacted to the ground than did Mexican folkloric dancers. On Spanish dancers, the working leg had more motion in relation to hip and knee angles than was seen in folkloric dancers. The ankle extensors were stronger on folkloric dancers, and there were no differences for the other muscle groups. Knee flexion at foot contact and muscle strength imbalance could be risk factors for injuries. It is suggested that the technique in Spanish dance in Mexico be reviewed, although more studies are required to define more risk factors. PMID:23752281

  5. Estimating 3D L5/S1 moments and ground reaction forces during trunk bending using a full-body ambulatory inertial motion capture system.

    Faber, G S; Chang, C C; Kingma, I; Dennerlein, J T; van Dieën, J H

    2016-04-11

    Inertial motion capture (IMC) systems have become increasingly popular for ambulatory movement analysis. However, few studies have attempted to use these measurement techniques to estimate kinetic variables, such as joint moments and ground reaction forces (GRFs). Therefore, we investigated the performance of a full-body ambulatory IMC system in estimating 3D L5/S1 moments and GRFs during symmetric, asymmetric and fast trunk bending, performed by nine male participants. Using an ambulatory IMC system (Xsens/MVN), L5/S1 moments were estimated based on the upper-body segment kinematics using a top-down inverse dynamics analysis, and GRFs were estimated based on full-body segment accelerations. As a reference, a laboratory measurement system was utilized: GRFs were measured with Kistler force plates (FPs), and L5/S1 moments were calculated using a bottom-up inverse dynamics model based on FP data and lower-body kinematics measured with an optical motion capture system (OMC). Correspondence between the OMC+FP and IMC systems was quantified by calculating root-mean-square errors (RMSerrors) of moment/force time series and the interclass correlation (ICC) of the absolute peak moments/forces. Averaged over subjects, L5/S1 moment RMSerrors remained below 10Nm (about 5% of the peak extension moment) and 3D GRF RMSerrors remained below 20N (about 2% of the peak vertical force). ICCs were high for the peak L5/S1 extension moment (0.971) and vertical GRF (0.998). Due to lower amplitudes, smaller ICCs were found for the peak asymmetric L5/S1 moments (0.690-0.781) and horizontal GRFs (0.559-0.948). In conclusion, close correspondence was found between the ambulatory IMC-based and laboratory-based estimates of back load. PMID:26795123

  6. Comparisons of knee and ankle joint angles and ground reaction force according to functional differences during single-leg drop landing

    Kim, Kewwan; Jeon, Kyoungkyu

    2016-01-01

    [Purpose] The purpose of this study was to determine potential predictors of functional instability of the knee and ankle joints during single-leg drop landing based on the prior history of injury. [Subjects and Methods] The subjects were 24 collegiate soccer players without pain or dysfunction. To compare the differences between the stable and unstable sides during single-leg drop landing, 8 motion analysis cameras and a force plate were used. The Cortex 4 software was used for a biomechanical analysis of 3 events. An independent t-test was used for statistical comparison between both sides; pknee joint movements showed gradual flexion in the sagittal plane. The unstable-side ankle joint showed plantar flexion of approximately 2° relative to the stable side. In the coronal plane, the unstable-side knee joint differed from the stable side in its tendency for valgus movement. The unstable-side ankle joint showed contrasting movement compared with the stable side, and the difference was significant. Regarding the vertical ground reaction force, the stable side showed maximum knee flexion that was approximately 0.1 BW lower than that of the unstable side. [Conclusion] Increasing the flexion angle of the knee joint can help prevent injury during landing.

  7. Predição da força de reação do solo durante a corrida na água Prediction of ground reaction force during water immersion running

    Alessandro Haupenthal

    2010-09-01

    Full Text Available Este estudo visou desenvolver um modelo para a predição da força de reação do solo na corrida subaquática. Participaram 20 sujeitos (9 homens e 11 mulheres, que realizaram corrida subaquática em dois níveis de imersão e três velocidades. Para cada sujeito foram coletadas seis passagens válidas em cada condição, com a utilização de uma plataforma subaquática de força. O modelo para predição da força foi construído por regressão linear múltipla. Foram consideradas variáveis dependentes a componente vertical e a componente ântero-posterior da força de reação do solo. As variáveis imersão, sexo, velocidade, massa corporal, densidade corporal e percentual de gordura foram consideradas independentes. Permaneceu no modelo final de regressão para a componente vertical a velocidade (pThis study aimed at developing a model to predict ground reaction force during deep-water running. A total of 20 subjects ((9 men, 11 women ran in water at two immersion levels and three different speeds. Each subject performed six valid trials in each condition, data being captured by an underwater force plate. The force prediction model was build by multiple linear regression. Dependent variables were the vertical and anteroposterior components of the ground reaction force; independent variables were runners' immersion, sex, speed, body mass, body density, and percentage of fat. At the final regression model for the vertical component, only speed remained (p<0.001, while for the anteroposterior component, speed, immersion, and body mass were maintained (all at p<0.001. The obtained model for the anteroposterior component of ground reaction force may be found satisfactory, as adjusted determination coefficient was 0.79. However, the prediction model for the vertical component cannot be recommended for prediction during deep-water running, since that coefficient was 0.18. It must be noted that the proposed prediction model applies to subjects

  8. Unmanned ground vehicles for integrated force protection

    Carroll, Daniel M.; Mikell, Kenneth; Denewiler, Thomas

    2004-09-01

    The combination of Command and Control (C2) systems with Unmanned Ground Vehicles (UGVs) provides Integrated Force Protection from the Robotic Operation Command Center. Autonomous UGVs are directed as Force Projection units. UGV payloads and fixed sensors provide situational awareness while unattended munitions provide a less-than-lethal response capability. Remote resources serve as automated interfaces to legacy physical devices such as manned response vehicles, barrier gates, fence openings, garage doors, and remote power on/off capability for unmanned systems. The Robotic Operations Command Center executes the Multiple Resource Host Architecture (MRHA) to simultaneously control heterogeneous unmanned systems. The MRHA graphically displays video, map, and status for each resource using wireless digital communications for integrated data, video, and audio. Events are prioritized and the user is prompted with audio alerts and text instructions for alarms and warnings. A control hierarchy of missions and duty rosters support autonomous operations. This paper provides an overview of the key technology enablers for Integrated Force Protection with details on a force-on-force scenario to test and demonstrate concept of operations using Unmanned Ground Vehicles. Special attention is given to development and applications for the Remote Detection Challenge and Response (REDCAR) initiative for Integrated Base Defense.

  9. Computerized identification and classification of stance phases as made by front og hind feet of walking cows based on 3-dimensional ground reaction forces

    Skjøth, F; Thorup, Vivi Mørkøre; do Nascimento, Omar Feix; Ingvartsen, Klaus Lønne; Rasmussen, Morten Dam; Voigt, Michael

    2013-01-01

    force information. Features were derived from measurements made using two parallel 3-dimensional force plates. The approach presented is based on clustering of Centre of Pressure (COP) trace points over space and time, combined with logical sequencing of stance phases based on the dynamics of...

  10. Effects of ground and joint reaction force exercise on lumbar spine and femoral neck bone mineral density in postmenopausal women: a meta-analysis of randomized controlled trials

    Kelley George A

    2012-09-01

    Full Text Available Abstract Background Low bone mineral density (BMD and subsequent fractures are a major public health problem in postmenopausal women. The purpose of this study was to use the aggregate data meta-analytic approach to examine the effects of ground (for example, walking and/or joint reaction (for example, strength training exercise on femoral neck (FN and lumbar spine (LS BMD in postmenopausal women. Methods The a priori inclusion criteria were: (1 randomized controlled trials, (2 exercise intervention ≥ 24 weeks, (3 comparative control group, (4 postmenopausal women, (5 participants not regularly active, i.e., less than 150 minutes of moderate intensity (3.0 to 5.9 metabolic equivalents weight bearing endurance activity per week, less than 75 minutes of vigorous intensity (> 6.0 metabolic equivalents weight bearing endurance activity per week, resistance training g was calculated for each FN and LS BMD result and pooled using random-effects models. Z-score alpha values, 95%confidence intervals (CI and number-needed-to-treat (NNT were calculated for pooled results. Heterogeneity was examined using Q and I2. Mixed-effects ANOVA and simple meta-regression were used to examine changes in FN and LS BMD according to selected categorical and continuous variables. Statistical significance was set at an alpha value ≤0.05 and a trend at >0.05 to ≤ 0.10. Results Small, statistically significant exercise minus control group improvements were found for both FN (28 g’s, 1632 participants, g = 0.288, 95% CI = 0.102, 0.474, p = 0.002, Q = 90.5, p I2 = 70.1%, NNT = 6 and LS (28 g’s, 1504 participants, g = 0.179, 95% CI = −0.003, 0.361, p = 0.05, Q = 77.7, p I2 = 65.3%, NNT = 6 BMD. Clinically, it was estimated that the overall changes in FN and LS would reduce the 20-year relative risk of osteoporotic fracture at any site by approximately 11% and 10%, respectively. None of the mixed

  11. About Radiation Reaction with Force Approach

    Velazquez, Gustavo Lopez

    2015-01-01

    The difficulty of usual approach to radiation reaction is pointed out , and a possible approach based on the force acting to the charged particle which produces the acceleration itself, is presented. This approach brings about an expression such that acceleration is zero whenever the external force is zero.

  12. Effects of shoeing on limb movement and ground reaction forces in Icelandic horses at walk, tölt and trot.

    Waldern, Nina M; Wiestner, Thomas; Ramseier, Lea C; Amport, Claude; Weishaupt, Michael A

    2013-12-01

    Tölt is a symmetric four-beat gait with a speed range extending into that of trot and canter. Specific shoeing methods, such as unnaturally high and long hooves, are used to enforce individual gait predisposition. The aim of this study was to assess the consequences of this shoeing style on loading and movement of the limbs at walk, tölt and trot, and at different velocities. Simultaneous kinetic and kinematic gait analysis was carried out at walk (1.4m/s) and at two tölting and trotting speeds (3.3m/s and 3.9 m/s) on an instrumented treadmill. Thirteen sound Icelandic horses were first measured with high, long front hooves (SH) and, 1 week later, after trimming the hooves according to standard shoeing principles (SN). Comparing SH with SN, front hooves had 21 ± 5 mm longer dorsal hoof walls, and the shoeing material per hoof was 273 ± 50 g heavier. In all three gaits, gait quality, as it is currently judged, was improved with SH due to a lower stride rate, a longer stride length and a higher, but not wider, forelimb protraction arc, which were also positively associated with speed. Forelimb-hind limb balance remained unchanged, but limb impulses were higher. Apart from an increase of ≤ 2.2% in the forelimbs at the faster speed of both tölt and trot, SH had little influence on vertical peak forces. PMID:24360730

  13. A vacuum--generated inertia reaction force

    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

  14. Grounding-Induced Sectional Forces and Residual Strength of Grounded Ship Hulls

    Paik, Jeom Kee; Pedersen, Preben Terndrup

    1996-01-01

    The aim of the present study is to determine the sectional forces induced by ship grounding and also to assess the residual strength of groundedship hulls. An analytical approach is used to estimate the grounding-induced sectional forces of ships. The extent and location of structural damage due to...... grounding is defined based on the ABS Safe Hull guide. The residual strength of damaged hulls is calculated by using a simple analytical formula. The method is applied to residual strength assessment of a damaged double hull tanker of 38,400 dwt due to grounding....

  15. Ground reaction curve based upon block theory

    Discontinuities in a rock mass can intersect an excavation surface to form discrete blocks (keyblocks) which can be unstable. Once a potentially unstable block is identified, the forces affecting it can be calculated to assess its stability. The normal and shear stresses on each block face before displacement are calculated using elastic theory and are modified in a nonlinear way by discontinuity deformations as the keyblock displaces. The stresses are summed into resultant forces to evaluate block stability. Since the resultant forces change with displacement, successive increments of block movement are examined to see whether the block ultimately becomes stable or fails. Two-dimensional (2D) and three-dimensional (3D) analytic models for the stability of simple pyramidal keyblocks were evaluated. Calculated stability is greater for 3D analyses than for 2D analyses. Calculated keyblock stability increases with larger in situ stress magnitudes, larger lateral stress ratios, and larger shear strengths. Discontinuity stiffness controls blocks displacement more strongly than it does stability itself. Large keyblocks are less stable than small ones, and stability increases as blocks become more slender

  16. Regulation of reaction forces during the golf swing.

    McNitt-Gray, J L; Munaretto, J; Zaferiou, A; Requejo, P S; Flashner, H

    2013-06-01

    During the golf swing, the reaction forces applied at the feet control translation and rotation of the body-club system. In this study, we hypothesized that skilled players using a 6-iron would regulate shot distance by scaling the magnitude of the resultant horizontal reaction force applied to the each foot with minimal modifications in force direction. Skilled players (n = 12) hit golf balls using a 6-iron. Shot distance was varied by hitting the ball as they would normally and when reducing shot distance using the same club. During each swing, reaction forces were measured using dual force plates (1200 Hz) and three-dimensional kinematics were simultaneously captured (110 Hz). The results indicate that, on average, the peak resultant horizontal reaction forces of the target leg were significantly less than normal (5%, p < 0.05) when reducing shot distance. No significant differences in the orientation of the peak resultant horizontal reaction forces were observed. Resultant horizontal reaction force-angle relationships within leg and temporal relationships between target and rear legs during the swing were consistent within player across shot conditions. Regulation of force magnitude with minimal modification in force direction is expected to provide advantages from muscle activation, coordination, and performance points of view. PMID:23898685

  17. The enemy below: preparing ground forces for subterranean warfare

    Bowes, Joshua S.; Newdigate, Mark T.; Rosario, Pedro J.; Tindoll, Davis D.

    2013-01-01

    Approved for public release; distribution is unlimited. This capstone project analyses subterranean threats in the contemporary operational environment. It identifies the doctrinal gap in the U.S. military regarding operations within tunnels, urban and natural cavities, and other underground facilities, and outlines the changes necessary to prepare ground forces to operate in these complex environments. This paper reviews historical cases spanning back over half a millennium, proposes a ne...

  18. Unattended ground sensors for Expeditionary Force 21 intelligence collections

    Harrington, Ryan F.

    2015-01-01

    Approved for public release; distribution is unlimited As our adversaries continue to evolve in complexity, the U.S. Marines adapt in kind with its design and intent through its Expeditionary Force 21 (EF 21) Capstone. EF 21 stresses the need for increased persistent intelligence collections capabilities and the optimization of existing assets. Current requirements for Unattended Ground Sensors (UGS) limit usage in non-permissive environments beyond the Area of Operations, contrary to the ...

  19. CHEMICAL REACTIONS SIMULATED BY GROUND-WATER-QUALITY MODELS.

    Grove, David B.; Stollenwerk, Kenneth G.

    1987-01-01

    Recent literature concerning the modeling of chemical reactions during transport in ground water is examined with emphasis on sorption reactions. The theory of transport and reactions in porous media has been well documented. Numerous equations have been developed from this theory, to provide both continuous and sequential or multistep models, with the water phase considered for both mobile and immobile phases. Chemical reactions can be either equilibrium or non-equilibrium, and can be quantified in linear or non-linear mathematical forms. Non-equilibrium reactions can be separated into kinetic and diffusional rate-limiting mechanisms. Solutions to the equations are available by either analytical expressions or numerical techniques. Saturated and unsaturated batch, column, and field studies are discussed with one-dimensional, laboratory-column experiments predominating. A summary table is presented that references the various kinds of models studied and their applications in predicting chemical concentrations in ground waters.

  20. On the Compensation of Dynamic Reaction Forces in Stationary Machinery

    Radermacher, Tobias; Lübbert, Jan; Weber, Jürgen

    2016-01-01

    This paper studies a method for active electrohydraulic force compensation in industrial scale high power applications. A valve controlled cylinder moves a mass using the force of inertia to compensate for the reaction forces of an industrial process. Two strategies for force compensation are developed and investigated in a 160 ton clamping unit of an injection moulding machine to significantly reduce the excitation. Results of the different strategies are shown and evaluated. Advantages and ...

  1. Analytical r-mode solution with gravitational radiation reaction force

    Dias, O J C; S\\'a, Paulo M.

    2005-01-01

    We present and discuss the analytical r-mode solution to the linearized hydrodynamic equations of a slowly rotating, Newtonian, barotropic, non-magnetized, perfect-fluid star in which the gravitational radiation reaction force is present.

  2. Relação entre a mobilidade do tornozelo e pé e a magnitude da força vertical de reação do solo Relationship between ankle and foot mobility and the magnitude of the vertical ground reaction force

    DL Vianna

    2006-09-01

    Full Text Available OBJETIVO: Verificar a relação entre a mobilidade do tornozelo e do pé, e o pico da força vertical de reação do solo, considerada como porcentagem do peso corporal, gerada durante a fase de apoio da marcha. MÉTODOS: foram estudados pés normais do lado direito e esquerdo de 15 homens com 22,1±2,7 anos (19-28 e 15 mulheres 24,20±5,24 anos (19-34. Os parâmetros de exclusão foram: deformidades nos pés, doenças ou traumas, que pudessem acometer o sistema musculoesquelético e a marcha. A mobilidade do tornozelo e dos pés foi obtida através da goniometria da flexão plantar, dorsiflexão, extensão do hálux e extensão dos dedos, o pico da força vertical de reação do solo FRS, foi obtido pela baropodometria computadorizada do sistema FSCAN R. A correlação entre ambas foi feita pelo teste estatístico de Spearman. RESULTADOS: os indivíduos do grupo masculino apresentaram menores valores de mobilidade, e maiores valores do pico da força vertical de reação do solo, quando comparados com o grupo feminino. Não houve diferença entre os pés direito e esquerdo. No sexo feminino foi encontrada correlação negativa estatisticamente significante entre os valores da flexão plantar e a força vertical, e entre os valores da extensão dos dedos e a foça vertical. No sexo masculino, houve correlação negativa estatisticamente significante entre os valores da dorsiflexão e a força vertical. Entre os demais valores não foi encontrada correlação significante. CONCLUSÃO: Há relação entre a mobilidade e a força vertical gerada durante a marcha.OBJECTIVE: To investigate the relationship between ankle and foot mobility and the peak of the vertical ground reaction force, as a percentage of body weight, generated during the gait stance phase. METHOD: Fifteen men with mean age of 22.1 ± 2.7 years (range: 19-28 and fifteen women with mean age of 24.20 ± 5.24 years (range: 19-34 with normal feet were studied. The exclusion criteria

  3. Computational Catalysis Using the Artificial Force Induced Reaction Method.

    Sameera, W M C; Maeda, Satoshi; Morokuma, Keiji

    2016-04-19

    The artificial force induced reaction (AFIR) method in the global reaction route mapping (GRRM) strategy is an automatic approach to explore all important reaction paths of complex reactions. Most traditional methods in computational catalysis require guess reaction paths. On the other hand, the AFIR approach locates local minima (LMs) and transition states (TSs) of reaction paths without a guess, and therefore finds unanticipated as well as anticipated reaction paths. The AFIR method has been applied for multicomponent organic reactions, such as the aldol reaction, Passerini reaction, Biginelli reaction, and phase-transfer catalysis. In the presence of several reactants, many equilibrium structures are possible, leading to a number of reaction pathways. The AFIR method in the GRRM strategy determines all of the important equilibrium structures and subsequent reaction paths systematically. As the AFIR search is fully automatic, exhaustive trial-and-error and guess-and-check processes by the user can be eliminated. At the same time, the AFIR search is systematic, and therefore a more accurate and comprehensive description of the reaction mechanism can be determined. The AFIR method has been used for the study of full catalytic cycles and reaction steps in transition metal catalysis, such as cobalt-catalyzed hydroformylation and iron-catalyzed carbon-carbon bond formation reactions in aqueous media. Some AFIR applications have targeted the selectivity-determining step of transition-metal-catalyzed asymmetric reactions, including stereoselective water-tolerant lanthanide Lewis acid-catalyzed Mukaiyama aldol reactions. In terms of establishing the selectivity of a reaction, systematic sampling of the transition states is critical. In this direction, AFIR is very useful for performing a systematic and automatic determination of TSs. In the presence of a comprehensive description of the transition states, the selectivity of the reaction can be calculated more accurately

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

    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

  5. A thermodynamic force generated by chemical gradient and adsorption reaction

    Sugawara, Takeshi

    2009-01-01

    Biological units such as macromolecules, organelles, and cells are directed to a proper location under gradients of relevant chemicals. By considering a macroscopic element that has binding sites for a chemical adsorption reaction to occur on its surface, we show the existence of a thermodynamic force that is generated by the gradient and exerted on the element. By assuming local equilibrium and adopting the grand potential from thermodynamics, we derive a formula for such a thermodynamic force, which depends on the chemical potential gradient and Langmuir isotherm. The conditions under which the formula can be applied are demonstrated to hold in intracellular reactions. The role of the force in the partitioning of bacterial chromosome/plasmid during cell division is discussed.

  6. Government Applications Task Force ground truth study of WAG 4

    Evers, T.K.; Smyre, J.L.; King, A.L.

    1997-06-01

    This report documents the Government Applications Task Force (GATF) Buried Waste Project. The project was initiated as a field investigation and verification of the 1994 Strategic Environmental Research and Development Program`s (SERDP) Buried Waste Identification Project results. The GATF project team included staff from three US Department of Energy (DOE) Laboratories [Oak Ridge National Laboratory (ORNL), Los Alamos National Laboratory (LANL), and the Savannah River Technology Center (SRTC)] and from the National Exploitation Laboratory. Similar studies were conducted at each of the three DOE laboratories to demonstrate the effective use of remote sensing technologies. The three locations were selected to assess differences in buried waste signatures under various environmental conditions (i.e., climate, terrain, precipitation, geology, etc.). After a brief background discussion of the SERDP Project, this report documents the field investigation (ground truth) results from the 1994--1995 GATF Buried Waste Study at ORNL`s Waste Area Grouping (WAG) 4. Figures for this report are located in Appendix A.

  7. The reaction force: Three key points along an intrinsic reaction coordinate

    Peter Politzer; Alejandro Toro-Labbé; Soledad Gutiérrez-Oliva; Bárbara herrera; Pablo Jaque; Monica C Concha; Jane S Murray

    2005-09-01

    The concept of the reaction force is presented and discussed in detail. For typical processes with energy barriers, it has a universal form which defines three key points along an intrinsic reaction coordinate: the force minimum, zero and maximum. We suggest that the resulting four zones be interpreted as involving preparation of reactants in the first, transition to products in the second and third, and relaxation in the fourth. This general picture is supported by the distinctive patterns of the variations in relevant electronic properties. Two important points that are brought out by the reaction force are that (a) the traditional activation energy comprises two separate contributions, and (b) the transition state corresponds to a balance between the driving and the retarding forces.

  8. A influência do uso acumulado de calçados de corrida sobre a força de reação do solo e as respostas de pressão plantar The influence of running shoes cumulative usage on the ground reaction forces and plantar pressure responses

    Roberto Bianco

    2011-12-01

    Full Text Available Acredita-se que a eficiência do calçado seja afetada pelo uso prolongado, mas as alterações biomecânicas ainda não estão bem compreendidas. O objetivo deste estudo é analisar a influência do uso de calçados de corrida na força de reação do solo e os parâmetros de pressão plantar. Três corredores do sexo masculino receberam quatro calçados de corrida para usarem em suas sessões de treinamento. O Sistema Gaitway e o Sistema de F-scan foram usados para registrar a força de reação do solo e parâmetros pressão plantar em diferentes regiões do pé. As coletas ocorreram em quatro momentos: novo e 100, 200 e 300 km de uso. O primeiro pico diminuiu da condição novo para os 300 km de uso (p The prolonged use of a running shoe is thought to affect the efficiency of its impact attenuation properties. However, its effect over biomechanical variables has yet not been well understood. The aim of this study was to examine the influence of running shoe usage on ground reaction force and plantar pressure parameters. Three male runners received four running shoes each to use at their training sessions. The Gaitway System was used to register the vertical component of the ground reaction force, whereas the contact area and peak plantar pressure at different regions of the foot were assessed via the the F-scan System. Data collection occurred at baseline (when the shoes were new - New and after 100, 200 and 300km of use. The first peak decreased significantly from New to 300km (p < 0.01 and the loading rate showed a significant decrease at 200km in relation to the New condition (p < 0.01. Total area increased significantly from New to 100km (p < 0.01 of use and maintained a similar value when compared with the other conditions. There was a continuous and significant decrease (p < 0.01 on forefoot peak pressure as the mileage increased from New to 300km. The hallux peak pressure values were significantly smaller (p < 0.01 at 300km when

  9. Reduction in ground reaction force variables with instructed barefoot running

    Cynthia D. Samaan; Michael J. Rainbow; Davis, Irene S.

    2014-01-01

    Backgound: Barefoot (BF) running has recently increased in popularity with claims that it is more natural and may result in fewer injuries due to a reduction in impact loading. However, novice BF runners do not necessarily immediately switch to a forefoot strike pattern. This may increase mechanical parameters such as loading rate, which has been associated with certain running-related injuries, specifically, tibial stress fractures, patellofemoral pain, and plantar fasciitis. The purpose of ...

  10. Reduction in ground reaction force variables with instructed barefoot running

    Cynthia D. Samaan

    2014-06-01

    Conclusion: As impact loading has been associated with certain running-related injuries, instruction and feedback on the proper forefoot strike pattern may help reduce the injury risk associated with transitioning to BF running.

  11. Crouched Posture Maximizes Ground Reaction Forces Generated by Muscles

    Hoang, Hoa X.; Reinbolt, Jeffrey A.

    2012-01-01

    Crouch gait decreases walking efficiency due to the increased knee and hip flexion during the stance phase of gait. Crouch gait is generally considered to be disadvantageous for children with cerebral palsy; however, a crouched posture may allow biomechanical advantages that lead some children to adopt a crouch gait. To investigate one possible advantage of crouch gait, a musculoskeletal model created in OpenSim was placed in 15 different postures from upright to severe crouch during initial,...

  12. Experimental verification of a computational technique for determining ground reactions in human bipedal stance.

    Audu, Musa L; Kirsch, Robert F; Triolo, Ronald J

    2007-01-01

    We have developed a three-dimensional (3D) biomechanical model of human standing that enables us to study the mechanisms of posture and balance simultaneously in various directions in space. Since the two feet are on the ground, the system defines a kinematically closed-chain which has redundancy problems that cannot be resolved using the laws of mechanics alone. We have developed a computational (optimization) technique that avoids the problems with the closed-chain formulation thus giving users of such models the ability to make predictions of joint moments, and potentially, muscle activations using more sophisticated musculoskeletal models. This paper describes the experimental verification of the computational technique that is used to estimate the ground reaction vector acting on an unconstrained foot while the other foot is attached to the ground, thus allowing human bipedal standing to be analyzed as an open-chain system. The computational approach was verified in terms of its ability to predict lower extremity joint moments derived from inverse dynamic simulations performed on data acquired from four able-bodied volunteers standing in various postures on force platforms. Sensitivity analyses performed with model simulations indicated which ground reaction force (GRF) and center of pressure (COP) components were most critical for providing better estimates of the joint moments. Overall, the joint moments predicted by the optimization approach are strongly correlated with the joint moments computed using the experimentally measured GRF and COP (0.78 unity slope (experimental=computational results) for postures of the four subjects examined. These results indicate that this model-based technique can be relied upon to predict reasonable and consistent estimates of the joint moments using the predicted GRF and COP for most standing postures. PMID:16797023

  13. Forced vibration tests of a model foundation on rock ground

    The response of very stiff structures, such as nuclear reactor buildings, to earthquake ground motion is significantly affected by radiation damping due to the soil-structure interaction. The radiation damping can be computed by vibration admittance theory or dynamical ground compliance theory. In order to apply the values derived from these theories to the practical problems, comparative studies between theoretical results and experimental results concerning the soil-structure interaction, especially if the ground is rock, are urgently needed. However, experimental results for rock are less easily obtained than theoretical ones. The purpose of this paper is to describe the harmonic excitation tests of a model foundation on rock and to describe the results of comparative studies. (orig./HP)

  14. The solar forcing on the ground 7 Be concentration variability

    7 Be, natural radionuclide, is produced by the interaction of cosmic radiation with oxygen and nitrogen molecules. 7 Be production in atmosphere depends on the intensity of cosmic radiation which is influenced by the Earth's magnetosphere. The magnetosphere shape depends on solar activity. This paper presents the influence of sunspots number (11 years period) on the ground 7 Be concentration variability. (authors)

  15. (Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio)

    1991-10-01

    This report presents information concerning field procedures employed during the monitoring, well construction, well purging, sampling, and well logging at the Wright-Patterson Air Force Base. Activities were conducted in an effort to evaluate ground water contamination.

  16. (Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio)

    1992-03-01

    This report presents information related to the sampling of ground water at the Wright-Patterson Air Force Base. It is part of an investigation into possible ground water contamination. Information concerns well drilling/construction; x-ray diffraction and sampling; soil boring logs; and chain-of-custody records.

  17. Tethered satellite system control using electromagnetic forces and reaction wheels

    Alandi Hallaj, Mohammad Amin; Assadian, Nima

    2015-12-01

    In this paper a novel non-rotating space tethered configuration is introduced which its relative positions controlled using electromagnetic forces. The attitude dynamics is controlled by three reaction wheels in the body axes. The nonlinear coupled orbital dynamics of a dumbbell tethered satellite formation flight are derived through a constrained Lagrangian approach. These equations are presented in the leader satellite orbital frame. The tether is assumed to be mass-less and straight, and the J2 perturbation is included to the analysis. The forces and the moments of the electromagnetic coils are modeled based on the far-filed model of the magnetic dipoles. A guidance scheme for generating the desired positions as a function of time in Cartesian form is presented. The satellite tethered formation with variable length is controlled utilizing a linear controller. This approach is applied to a specified scenario and it is shown that the nonlinear guidance method and the linear controller can control the nonlinear system of the tethered formation and the results are compared with optimal control approach.

  18. Fore-aft ground force adaptations to induced forelimb lameness in walking and trotting dogs.

    Abdelhadi, Jalal; Wefstaedt, Patrick; Nolte, Ingo; Schilling, Nadja

    2012-01-01

    Animals alter their locomotor mechanics to adapt to a loss of limb function. To better understand their compensatory mechanisms, this study evaluated the changes in the fore-aft ground forces to forelimb lameness and tested the hypothesis that dogs unload the affected limb by producing a nose-up pitching moment via the exertion of a net-propulsive force when the lame limb is on the ground. Seven healthy Beagles walked and trotted at steady speed on an instrumented treadmill while horizontal force data were collected before and after a moderate lameness was induced. Peak, mean and summed braking and propulsive forces as well as the duration each force was exerted and the time to reach maximum force were evaluated for both the sound and the lame condition. Compared with the sound condition, a net-propulsive force was produced by the lame diagonal limbs due to a reduced braking force in the affected forelimb and an increased propulsive force in the contralateral hindlimb when the dogs walked and trotted. To regain pitch stability and ensure steady speed for a given locomotor cycle, the dogs produced a net-braking force when the sound diagonal limbs were on the ground by exerting greater braking forces in both limbs during walking and additionally reducing the propulsive force in the hindlimb during trotting. Consistent with the proposed mechanism, dogs maximize their double support phases when walking. Likely associated with the fore-aft force adaptations to lameness are changes in muscle recruitment that potentially result in short- and long-term effects on the limb and trunk muscles. PMID:23300614

  19. Fore-Aft Ground Force Adaptations to Induced Forelimb Lameness in Walking and Trotting Dogs

    Abdelhadi, Jalal; Wefstaedt, Patrick; Nolte, Ingo; Schilling, Nadja

    2012-01-01

    Animals alter their locomotor mechanics to adapt to a loss of limb function. To better understand their compensatory mechanisms, this study evaluated the changes in the fore-aft ground forces to forelimb lameness and tested the hypothesis that dogs unload the affected limb by producing a nose-up pitching moment via the exertion of a net-propulsive force when the lame limb is on the ground. Seven healthy Beagles walked and trotted at steady speed on an instrumented treadmill while horizontal f...

  20. Resolution of Forces and Strain Measurements from an Acoustic Ground Test

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

    2013-01-01

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

  1. Decrease of reaction force of metal gaskets just after initial tightening

    The decrease of reaction force of some metal gaskets inserted into the test flange at room temperature, 120 C(real cask temperature) and 200 C(accelerated condition) are measured. The reaction forces of metal gaskets in the room temperature have been almost not changed. The reaction force of 120 C and 200 C metal gaskets has decreased according to the temperature increase. After the temperature became stable, the decrease of the reaction force gradually proceeded, this decrease have been as same as previous studies. The bolts of transport and storage casks are usually tightened just after the loading of spent fuels, and then the temperature of metal gaskets at that time is almost the room temperature. The reaction forces of the metal gasket tightened at this condition would be decreased after the temperature increase due to the decay heat of spent fuels. It is confirmed that the loosening of the bolts might be happened if the tightening torque of bolts is not appropriate. It is easy to evaluate that the reaction forces of the metal gasket in storage condition according to Larson-Miller parameter or relaxation of the gasket material, but the decrease of the reaction forces of the metal gasket just after the loading is not able to evaluate by these method. It is necessary to evaluate the reaction forces according to plastic deformation property of the metal gaskets so as to fasten the gaskets safety

  2. Influence of joint models on lower-limb musculo-tendon forces and threedimensional joint reaction forces during gait

    Dumas, Raphaël; Moissenet, Florent; GASPARUTTO, Xavier; CHEZE, Laurence

    2012-01-01

    Several three-dimensional (3D) lower-limb musculo-skeletal models have been developed for gait analysis and different hip, knee and ankle joint models have been considered in the literature. Conversely to the influence of the musculotendon geometry, the influence of the joint models - i.e. number of degrees of freedom and passive joint moments - on the estimated musculo-tendon forces and 3D joint reaction forces has not been extensively examined. In this paper musculo-tendon forces and 3D joi...

  3. Foot Reaction Forces during Long Duration Space Flight

    Gopalakrishnan, R.; Rice, A. J.; Genc, K. O.; Maender, C. C.; Kuklis, M. M.; Humphreys, B.; Cavanagh, P. R.

    2008-01-01

    Musculoskeletal changes, particularly in the lower extremities, are an established consequence of long-duration space flight despite exercise countermeasures. It is widely believed that disuse and reduction in load bearing are key to these physiological changes, but no quantitative data characterizing the on-orbit movement environments currently exist. Here we present data from the Foot Experiment (E318) regarding astronaut activity on the ground and on-orbit during typical days from 4 International Space Station (ISS) crew members who flew during increments 6, 8, 11, and 12.

  4. (Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio)

    1992-03-01

    An environmental investigation of ground water conditions has been undertaken at Wright-Patterson Air Force Base (WPAFB), Ohio to obtain data to assist in the evaluation of a potential removal action to prevent, to the extent practicable, migration of the contaminated ground water across Base boundaries. Field investigations were limited to the central section of the southwestern boundary of Area C and the Springfield Pike boundary of Area B. Further, the study was limited to a maximum depth of 150 feet below grade. Three primary activities of the field investigation were: (1) installation of 22 monitoring wells, (2) collection and analysis of ground water from 71 locations, (3) measurement of ground water elevations at 69 locations. Volatile organic compounds including trichloroethylene, perchloroethylene, and/or vinyl chloride were detected in concentrations exceeding Maximum Contaminant Levels (MCL) at three locations within the Area C investigation area. Ground water at the Springfield Pike boundary of Area B occurs in two primary units, separated by a thicker-than-expected clay layers. One well within Area B was determined to exceed the MCL for trichloroethylene.

  5. (Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio)

    1991-10-01

    In April 1990 Wright-Patterson Air Force Base (WPAFB) initiated an investigation to evaluate a potential CERCLA removal action to prevent, to the extent practicable, the migration of ground-water contamination in the Mad River Valley Aquifer within and across WPAFB boundaries. The action will be based on a Focused Feasibility Study with an Action Memorandum serving as a decision document that is subject to approval by the Ohio Environmental Protection Agency. The first phase (Phase 1) of this effort involves an investigation of ground-water contamination migrating across the southwest boundary of Area C and across Springfield Pike adjacent to Area B. Task 4 of Phase 1 is a field investigation to collect sufficient additional information to evaluate removal alternatives. The field investigation will provide information in the following specific areas of study: water-level data which will be used to permit calibration of the ground-water flow model to a unique time in history; and ground-water quality data which will be used to characterize the current chemical conditions of ground water.

  6. Thinking anew causality problems for the radiation reaction force

    Souza, Reinaldo de Melo e

    2015-01-01

    In this work, we analyze a Lagrangian formalism recently proposed to approach the issue of the Abraham-Lorentz force. Instead of involving only position and velocity, as usual in Classical Mechanics, this Lagrangian involves the acceleration of the charge. We find the conserved momentum of the charge in the absence of any field and show that it contains an acceleration term. This enables us to re-visit the well-known pre-acceleration problem and show that, contrary to what has been widely believed, it is not related to any violation of causality.

  7. VTOL in ground effect flows for closely spaced jets. [to predict pressure and upwash forces on aircraft structures

    Migdal, D.; Hill, W. G., Jr.; Jenkins, R. C.

    1979-01-01

    Results of a series of in ground effect twin jet tests are presented along with flow models for closely spaced jets to help predict pressure and upwash forces on simulated aircraft surfaces. The isolated twin jet tests revealed unstable fountains over a range of spacings and jet heights, regions of below ambient pressure on the ground, and negative pressure differential in the upwash flow field. A separate computer code was developed for vertically oriented, incompressible jets. This model more accurately reflects fountain behavior without fully formed wall jets, and adequately predicts ground isobars, upwash dynamic pressure decay, and fountain lift force variation with height above ground.

  8. Behavior of temporal parameters of the ground reactive forces for the walking of postmenopausal women.

    DE Sousa, Adriana Leite; Calçadas Dias Gabriel, Ronaldo Eugênio; Faria, Aurélio Marques; Aragão, Florbela R; Rodrigues Moreira, Maria Helena

    2015-01-01

    The study aimed to examine the influence of body composition and menopause characteristics on certain temporal parameters of the behavior of vertical and anteroposterior components of ground reactive forces, as well as the vertical and anteroposterior rates on the walking of postmenopausal women. The sample consisted of 67 postmenopausal women, average age 59 years. Body composition was assessed by octapolar bioimpedance and ground reactive force by the Kistler force platform. Vertical loading rate correlated positively with age (r = 0.02) and negatively with weight (r = -0.33). The relationship between the rates of vertical loading and unloading associated positively with menopause time (r = 0.27) but negatively with weight (r = -0.27). Vertical unloading rate showed a negative association with abdominal visceral adiposity (r = -0.27). The relationship between the times of the intermediate and final phases of the support correlated significantly with abdominal visceral adiposity (r = 0.25) and fat mass (r = 0.24). The study suggests that fat mass and abdominal visceral adiposity affect the support time, and increased abdominal visceral adiposity implies a slower pre-suspension phase during the walking of postmenopausal women. Hormone replacement therapy was shown to be an enhancer of steeper vertical loading and anteroposterior unloading and longer time in the double support phase, indicating a greater stability of postmenopausal women when walking. PMID:26686563

  9. Role of the radiation-reaction force in the optical response of two-dimensional crystals

    Merano, Michele

    2016-01-01

    A classical theory of a radiating two-dimensional crystal is proposed and an expression for the radiative-reaction force is derived. It is shown how this force, acting on the dipoles forming the material, induces a flow of energy away from the dipole vibrations into radiative electromagnetic energy. As conservation of energy requires, the time-average work per unit time and unit area done by the radiation-reaction force is negative and equal in absolute value to the time-average intensity radiated by the crystal.

  10. Radiation Reaction as a Non-conservative Force

    Aashish, Sandeep

    2016-01-01

    We study a system of a finite-size charged particle and electromagnetic field by exploiting the Hamilton's principle for classical non-conservative systems introduced recently by Galley[1] and obtain the equation of motion of the charged particle which turns out to be the same as obtained by Jackson[2]. We show that radiation reaction stems from the non-conservative potential of the effective Lagrangian. We derive the Abraham-Lorentz equation using the effective non-conservative Lagrangian for a point charge. We establish a correspondence between a charge interacting with its own electromagnetic field and that of a particle interacting with infinite bath oscillators which in turn affords a way to justify the non-conservative nature of the former system.

  11. [Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio

    This Removal Action System Design has been prepared as a Phase I Volume for the implementation of the Phase II removal action at Wright-Patterson Air Force Base (WPAFB) near Dayton, Ohio. The objective of the removal action is to prevent, to the extent practicable, the migration of ground water contaminated with chlorinated volatile organic compounds (VOCS) across the southwest boundary of Area C. The Phase 1, Volume 9 Removal Action System Design compiles the design documents prepared for the Phase II Removal Action. These documents, which are presented in Appendices to Volume 9, include: Process Design, which presents the 30 percent design for the ground water treatment system (GWTS); Design Packages 1 and 2 for Earthwork and Road Construction, and the Discharge Pipeline, respectively; no drawings are included in the appendix; Design Package 3 for installation of the Ground Water Extraction Well(s); Design Package 4 for installation of the Monitoring Well Instrumentation; and Design Package 5 for installation of the Ground Water Treatment System; this Design Package is incorporated by reference because of its size

  12. (Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio)

    1992-04-01

    This Removal Action System Design has been prepared as a Phase I Volume for the implementation of the Phase II removal action at Wright-Patterson Air Force Base (WPAFB) near Dayton, Ohio. The objective of the removal action is to prevent, to the extent practicable, the migration of ground water contaminated with chlorinated volatile organic compounds (VOCS) across the southwest boundary of Area C. The Phase 1, Volume 9 Removal Action System Design compiles the design documents prepared for the Phase II Removal Action. These documents, which are presented in Appendices to Volume 9, include: Process Design, which presents the 30 percent design for the ground water treatment system (GWTS); Design Packages 1 and 2 for Earthwork and Road Construction, and the Discharge Pipeline, respectively; no drawings are included in the appendix; Design Package 3 for installation of the Ground Water Extraction Well(s); Design Package 4 for installation of the Monitoring Well Instrumentation; and Design Package 5 for installation of the Ground Water Treatment System; this Design Package is incorporated by reference because of its size.

  13. (Environmental investigation of ground water contamination at Wright- Patterson Air Force Base, Ohio)

    1991-10-01

    This Health and Safety Plan (HSP) was developed for the Environmental Investigation of Ground-water Contamination Investigation at Wright-Patterson Air Force Base near Dayton, Ohio, based on the projected scope of work for the Phase 1, Task 4 Field Investigation. The HSP describes hazards that may be encountered during the investigation, assesses the hazards, and indicates what type of personal protective equipment is to be used for each task performed. The HSP also addresses the medical monitoring program, decontamination procedures, air monitoring, training, site control, accident prevention, and emergency response.

  14. Ground-based measurements of aerosol optical properties and radiative forcing in North China

    Hongbin Chen; Xiangao Xia; Pucai Wang; Wenxing Zhang

    2007-01-01

    In order to gain an insight into the aerosol properties and their climatic effect over the continental source regions of China, it is of significance to carry out long-term ground-based measurements of aerosol optical properties and radiative forcing. A couple of temporary and permanent Aerosol Robotic Network (AERONET) sites and three comprehensive radiative sites were established in China as a result of international cooperation in recent years. Heavy aerosol loading and significant temporal and spatial variation over North China are revealed by the AERONET data.Aerosol-induced reductions in surface radiation budget are examined on the basis of collocated observations by sun photometers and pyranometers.

  15. Forcing factors of cloud-to-ground lightning over Iberia: regional-scale assessments

    J. A. Santos

    2013-07-01

    Full Text Available Cloud-to-ground lightning in a sector covering the Iberian Peninsula, the Balearic Islands and nearby seas (36–44° N, 10° W–5° E is analysed in the period from 2003 to 2009 (7 yr. Two Iberian lightning detection networks, composed of 18 sensors over Portugal and Spain, are combined for the first time in the present study. The selected characteristics are cloud-to-ground flashes (CGFs, first stroke peak current, polarity and multiplicity (number of strokes in a given flash. This study examines the temporal (on hourly, monthly and seasonal timescales and spatial variability of CGFs. The influence of five forcing factors on lightning (elevation, lifted index, convective available potential energy and daily minimum and maximum near-surface air temperatures over the Iberian sector is also assessed. For regional-scale assessments, six subsectors with different climatic conditions were analysed separately. Despite important regional differences, the strongest lightning activity occurs from late spring to early autumn, and mostly in the afternoon. Furthermore, CGFs are mainly located over high-elevation areas in late spring to summer, while they tend to occur over the sea in autumn. The results suggest that (1 orographically forced thunderstorms over mountainous areas, mostly from May to September, (2 tropospheric buoyancy forcing over western-central and northern regions in summer and over the Mediterranean regions in autumn, and (3 near-surface thermal contrasts from October to February largely control the location of lightning in Iberia. There is no evidence of different forcings by polarity. A clear correspondence between summertime precipitation patterns and CGFs is also found.

  16. Influence of Muscle-Tendon Wrapping on Calculations of Joint Reaction Forces in the Equine Distal Forelimb

    Pandy, Marcus G.; Colin Burvill; Davies, Helen M. S.; Merritt, Jonathan S.

    2008-01-01

    The equine distal forelimb is a common location of injuries related to mechanical overload. In this study, a two-dimensional model of the musculoskeletal system of the region was developed and applied to kinematic and kinetic data from walking and trotting horses. The forces in major tendons and joint reaction forces were calculated. The components of the joint reaction forces caused by wrapping of tendons around sesamoid bones were found to be of similar magnitude to the reaction forces betw...

  17. Cloud-to-ground lightning in Portugal: patterns and dynamical forcing

    J. A. Santos

    2012-03-01

    Full Text Available An analysis of the cloud-to-ground discharges (CGD over Portugal is carried out using data collected by a network of sensors maintained by the Portuguese Meteorological Institute for 2003–2009 (7 yr. Only cloud-to-ground flashes are considered and negative polarity CGD are largely dominant. The total number of discharges reveals a considerable interannual variability and a large irregularity in their distribution throughout the year. However, it is shown that a large number of discharges occur in the May–September period (71%, with a bimodal distribution that peaks in May and September, with most of the lightning activity recorded in the afternoon (from 16:00 to 18:00 UTC. In spring and autumn the lightning activity tends to be scattered throughout the country, whereas in summer it tends to be more concentrated over northeastern Portugal. Winter generally presents low lightning activity. Furthermore, two significant couplings between the monthly number of days with discharges and the large-scale atmospheric circulation are isolated: a regional forcing, predominantly in summer, and a remote forcing. In fact, the identification of daily lightning regimes revealed three important atmospheric conditions for triggering lightning activity: regional cut-off lows, cold troughs induced by remote low pressure systems and summertime regional low pressures at low-tropospheric levels combined with a mid-tropospheric cold trough.

  18. Cloud-to-ground lightning in Portugal: patterns and dynamical forcing

    Santos, J. A.; Reis, M. A.; Sousa, J.; Leite, S. M.; Correia, S.; Janeira, M.; Fragoso, M.

    2012-03-01

    An analysis of the cloud-to-ground discharges (CGD) over Portugal is carried out using data collected by a network of sensors maintained by the Portuguese Meteorological Institute for 2003-2009 (7 yr). Only cloud-to-ground flashes are considered and negative polarity CGD are largely dominant. The total number of discharges reveals a considerable interannual variability and a large irregularity in their distribution throughout the year. However, it is shown that a large number of discharges occur in the May-September period (71%), with a bimodal distribution that peaks in May and September, with most of the lightning activity recorded in the afternoon (from 16:00 to 18:00 UTC). In spring and autumn the lightning activity tends to be scattered throughout the country, whereas in summer it tends to be more concentrated over northeastern Portugal. Winter generally presents low lightning activity. Furthermore, two significant couplings between the monthly number of days with discharges and the large-scale atmospheric circulation are isolated: a regional forcing, predominantly in summer, and a remote forcing. In fact, the identification of daily lightning regimes revealed three important atmospheric conditions for triggering lightning activity: regional cut-off lows, cold troughs induced by remote low pressure systems and summertime regional low pressures at low-tropospheric levels combined with a mid-tropospheric cold trough.

  19. (Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio)

    Thompson, Bill

    1991-10-01

    In April 1990, Wright-Patterson Air Force Base (WPAFB), initiated an investigation to evaluate a potential Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) removal action to prevent, to the extent practicable, the offsite migration of contaminated ground water from WPAFB. WPAFB retained the services of the Environmental Management Operations (EMO) and its principle subcontractor, International Technology Corporation (IT) to complete Phase 1 of the environmental investigation of ground-water contamination at WPAFB. Phase 1 of the investigation involves the short-term evaluation and potential design for a program to remove ground-water contamination that appears to be migrating across the western boundary of Area C, and across the northern boundary of Area B along Springfield Pike. Primarily, Task 4 of Phase 1 focuses on collection of information at the Area C and Springfield Pike boundaries of WPAFB. This Sampling and Analysis Plan (SAP) has been prepared to assist in completion of the Task 4 field investigation and is comprised of the Quality Assurance Project Plan (QAPP) and the Field Sampling Plan (FSP).

  20. Quasi in situ scanning force microscope with an automatic operated reaction chamber.

    Hund, Markus; Olszowka, Violetta; Fischer, Franz; Krejtschi, Heinz

    2011-11-01

    We describe the design and performance of a quasi in situ scanning force microscope with an automatic operated reaction chamber. The design provides a repetitive hermetically sealed sample environment for successive processing. The reaction chamber is based on a combination of a flexure-guided cover, a piezo-positioning system and a force applicator system. An axial force seals the cover against the reactor enabling flow-through applications at low pressure, ambient pressure, or elevated pressure. The position stability of the sample relative to the probe is characterized and a full automated operation of the instrument is explored by the alignment of an ABC terblock copolymer thin film undergoing solvent vapor annealing in the presence of a high electric field. Due to the high electric field strength and the sharp scanning force microscope tip it is impossible to perform in situ scanning in the presence of the electric field. PMID:22128986

  1. Measurement of muscle actions and foot reaction forces from crew members during entire working days on the International Space Station (ISS)

    We present pilot work in preparation for ISS Experiment 318, which will investigate changes in lower limb daily mechanical loading and muscular activity profiles that have been implicated in bone mineral loss and muscle atrophy during spaceflight. Prototype equipment for the musculo-skeletal rack of the Human Research Facility (HRF) was used in conjunction with the Ambulatory Data Acquisition System to record and store data. Right foot ground reaction force profiles, right leg EMG activity profiles from the tibialis anterior and vastus medialis, and joint angular excursion profiles from the right knee and ankle were collected during five minutes each of forward and backward running in 1g as well as over a twelve hour period of activities during daily living. Ground reaction force profiles were analyzed to provide an estimate of 1g daily mechanical load stimulus, while EMG and joint angle profiles characterized the role of individual muscles in generating and absorbing energy

  2. BALANCE : a computer program for calculating mass transfer for geochemical reactions in ground water

    Parkhurst, David L.; Plummer, L. Niel; Thorstenson, Donald C.

    1982-01-01

    BALANCE is a Fortran computer designed to define and quantify chemical reactions between ground water and minerals. Using (1) the chemical compositions of two waters along a flow path and (2) a set of mineral phases hypothesized to be the reactive constituents in the system, the program calculates the mass transfer (amounts of the phases entering or leaving the aqueous phase) necessary to account for the observed changes in composition between the two waters. Additional constraints can be included in the problem formulation to account for mixing of two end-member waters, redox reactions, and, in a simplified form, isotopic composition. The computer code and a description of the input necessary to run the program are presented. Three examples typical of ground-water systems are described. (USGS)

  3. Violation of action--reaction and self-forces induced by nonequilibrium fluctuations

    Buenzli, P. R.; Soto, R.

    2008-01-01

    We show that the extension of Casimir-like forces to fluctuating fluids driven out of equilibrium can exhibit two interrelated phenomena forbidden at equilibrium: self-forces can be induced on single asymmetric objects and the action--reaction principle between two objects can be violated. These effects originate in asymmetric restrictions imposed by the objects' boundaries on the fluid's fluctuations. They are not ruled out by the second law of thermodynamics since the fluid is in a nonequil...

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

    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

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

    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.

  6. Knee joint reaction force during tibial diaphyseal lengthening: a study on a rabbit model.

    Yang, Lang; Cai, Gang; Coulton, Les; Saleh, Michael

    2004-07-01

    The in vivo passive knee joint reaction force was measured in a rabbit model of tibial diaphyseal lengthening. This was based on the assumption that limb lengthening creates soft tissue tension that compresses the joint surface and generates the joint contact force. A measurement method was developed that involved the distraction of the joint and the determination of the distraction force that just separates the joint surfaces. Sixteen immature (mean+/-SD age=9+/-0.6 weeks) New Zealand White rabbits underwent 30% (left) tibial diaphyseal lengthening at a rate of two 0.4mm incremental lengthenings per day. The knee joint reaction force was measured at the end of lengthening (8 rabbits, mean+/-SD age=14+/-0.6 weeks) and five weeks after lengthening (8 rabbits, mean+/-SD age=19+/-0.7 weeks). An instrumented bilateral distractor and an extensometer were fixed cross the knee joint. The joint distraction force and distraction displacement were measured when the joint was distracted in steps and after the section of the Achilles tendon. The joint reaction force on the lengthened side was significantly higher than the control side at both time points (mean+/-SD 44.4+/-7.8 N v. 27.2+/-4.0 N at the end of lengthening, 44.3+/-S6.5 N v. 31.3+/-3.0 N at 5 weeks after lengthening). The contribution of the gastrocnemius to the joint reaction force on the lengthened side was also significantly higher than the control side at both time points (mean+/-SD 9.0+/-1.3N v. 2.8+/-0.8 N at the end of lengthening, 5.3+/-1.4N v. 2.7+/-0.5N at 5 weeks after lengthening). There were significant knee and ankle joint contractures at the end of lengthening, as evidenced by decreased range of motion (mean+/-SD 27+/-8 degrees and 36+/-13 degrees, respectively), which remained 5 weeks after lengthening (mean+/-SD 26+/-6 degrees and 35+/-8 degrees, respectively). The gastrocnemius contributed about 20% of the joint reaction force, indicating that changes in the other intra- and extra

  7. Aerodynamic forces and flow structures of the leading edge vortex on a flapping wing considering ground effect

    The aim of this work is to provide an insight into the aerodynamic performance of the beetle during takeoff, which has been estimated in previous investigations. We employed a scaled-up electromechanical model flapping wing to measure the aerodynamic forces and the three-dimensional flow structures on the flapping wing. The ground effect on the unsteady forces and flow structures were also characterized. The dynamically scaled wing model could replicate the general stroke pattern of the beetle's hind wing kinematics during takeoff flight. Two wing kinematic models have been studied to examine the influences of wing kinematics on unsteady aerodynamic forces. In the first model, the angle of attack is asymmetric and varies during the translational motion, which is the flapping motion of the beetle's hind wing. In the second model, the angle of attack is constant during the translational motion. The instantaneous aerodynamic forces were measured for four strokes during the beetle's takeoff by the force sensor attached at the wing base. Flow visualization provided a general picture of the evolution of the three-dimensional leading edge vortex (LEV) on the beetle hind wing model. The LEV is stable during each stroke, and increases radically from the root to the tip, forming a leading-edge spiral vortex. The force measurement results show that the vertical force generated by the hind wing is large enough to lift the beetle. For the beetle hind wing kinematics, the total vertical force production increases 18.4% and 8.6% for the first and second strokes, respectively, due to the ground effect. However, for the model with a constant angle of attack during translation, the vertical force is reduced during the first stroke. During the third and fourth strokes, the ground effect is negligible for both wing kinematic patterns. This finding suggests that the beetle's flapping mechanism induces a ground effect that can efficiently lift its body from the ground during takeoff

  8. Aerodynamic forces and flow structures of the leading edge vortex on a flapping wing considering ground effect.

    Van Truong, Tien; Byun, Doyoung; Kim, Min Jun; Yoon, Kwang Joon; Park, Hoon Cheol

    2013-09-01

    The aim of this work is to provide an insight into the aerodynamic performance of the beetle during takeoff, which has been estimated in previous investigations. We employed a scaled-up electromechanical model flapping wing to measure the aerodynamic forces and the three-dimensional flow structures on the flapping wing. The ground effect on the unsteady forces and flow structures were also characterized. The dynamically scaled wing model could replicate the general stroke pattern of the beetle's hind wing kinematics during takeoff flight. Two wing kinematic models have been studied to examine the influences of wing kinematics on unsteady aerodynamic forces. In the first model, the angle of attack is asymmetric and varies during the translational motion, which is the flapping motion of the beetle's hind wing. In the second model, the angle of attack is constant during the translational motion. The instantaneous aerodynamic forces were measured for four strokes during the beetle's takeoff by the force sensor attached at the wing base. Flow visualization provided a general picture of the evolution of the three-dimensional leading edge vortex (LEV) on the beetle hind wing model. The LEV is stable during each stroke, and increases radically from the root to the tip, forming a leading-edge spiral vortex. The force measurement results show that the vertical force generated by the hind wing is large enough to lift the beetle. For the beetle hind wing kinematics, the total vertical force production increases 18.4% and 8.6% for the first and second strokes, respectively, due to the ground effect. However, for the model with a constant angle of attack during translation, the vertical force is reduced during the first stroke. During the third and fourth strokes, the ground effect is negligible for both wing kinematic patterns. This finding suggests that the beetle's flapping mechanism induces a ground effect that can efficiently lift its body from the ground during takeoff

  9. Optimal control of the initiation of a pericyclic reaction in the electronic ground state

    Timm Bredtmann; Jörn Manz

    2012-01-01

    Pericyclic reactions in the electronic ground state may be initiated by down-chirped pump-dump sub-pulses of an optimal laser pulse, in the ultraviolet (UV) frequency and sub-10 femtosecond (fs) time domain. This is demonstrated by means of a quantum dynamics model simulation of the Cope rearrangement of Semibullvalene. The laser pulse is designed by means of optimal control theory, with detailed analysis of the mechanism. The theoretical results support the recent experimental initiation of a pericyclic reaction. The present approach provides an important step towards monitoring asynchronous electronic fluxes during synchronous nuclear pericyclic reaction dynamics, with femto-to-attosecond time resolution, as motivated by the recent prediction of our group.

  10. The effects of hibernation and forced disuse (neurectomy) on bone properties in arctic ground squirrels.

    Bogren, Lori K; Johnston, Erin L; Barati, Zeinab; Martin, Paula A; Wojda, Samantha J; Van Tets, Ian G; LeBlanc, Adrian D; Donahue, Seth W; Drew, Kelly L

    2016-05-01

    Bone loss is a well-known medical consequence of disuse such as in long-term space flight. Immobilization in many animals mimics the effects of space flight on bone mineral density. Decreases in metabolism are also thought to contribute to a loss of skeletal mass. Hibernating mammals provide a natural model of disuse and metabolic suppression. Hibernating ground squirrels have been shown to maintain bone strength despite long periods of disuse and decreased metabolism during torpor. This study examined if the lack of bone loss during torpor was a result of the decrease in metabolic rate during torpor or an evolutionary change in these animals affording protection against disuse. We delineated changes in bone density during natural disuse (torpor) and forced disuse (sciatic neurectomy) in the hind limbs of the arctic ground squirrel (AGS) over an entire year. We hypothesized that the animals would be resistant to bone loss due to immobilization and disuse during the winter hibernation season when metabolism is depressed but not the summer active season. This hypothesis was not supported. The animals maintained bone density (dual-energy X-ray absorptiometry) and most bone structural and mechanical properties in both seasons. This was observed in both natural and forced disuse, regardless of the known metabolic rate increase during the summer. However, trabecular bone volume fraction (microcomputed tomography) in the distal femur was lower in neurectomized AGS at the study endpoint. These results demonstrate a need to better understand the relationship between skeletal load (use) and bone density that may lead to therapeutics or strategies to maintain bone density in disuse conditions. PMID:27225624

  11. (Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio)

    1991-10-01

    In April 1990, Wright-Patterson Air Force Base (WPAFB) initiated an effort for the evaluation of potential removal of ground water contamination at the Base. This report presents a current assessment of the nature and extent of the contamination believed to be migrating across the southwestern boundary of Area C and the northern boundary of Area B based upon analysis of existing environmental data obtained from several sources. The existing data base indicates widespread, low-level contamination moving across Base boundaries at levels that pose no immediate threat to the Mad River Valley well fields. An investigation by the City of Dayton in May and June 1990, however, implies that a more identifiable plume of PCE and TCE may be crossing the southwestern boundary of Area C immediately downgradient of Landfill 5. More data is needed to delineate ground water contamination and to design and implement a suitable control system. This report concludes that although an extensive study of the boundaries in question would be the preferred approach, a limited, focused investigation and subsequent feasibility study can be accomplished with a reasonable certainty of achieving the desired outcome of this project.

  12. The mechanism of chemisorption of hydrogen atom on graphene: Insights from the reaction force and reaction electronic flux

    At the PBE-D3/cc-pVDZ level of theory, the hydrogen chemisorption on graphene was analyzed using the reaction force and reaction electronic flux (REF) theories in combination with electron population analysis. It was found that chemisorption energy barrier is mainly dominated by structural work (∼73%) associated to the substrate reconstruction whereas the electronic work is the greatest contribution of the reverse energy barrier (∼67%) in the desorption process. Moreover, REF shows that hydrogen chemisorption is driven by charge transfer processes through four electronic events taking place as H approaches the adsorbent surface: (a) intramolecular charge transfer in the adsorbent surface; (b) surface reconstruction; (c) substrate magnetization and adsorbent carbon atom develops a sp3 hybridization to form the σC-H bond; and (d) spontaneous intermolecular charge transfer to reach the final chemisorbed state

  13. Influence of Muscle-Tendon Wrapping on Calculations of Joint Reaction Forces in the Equine Distal Forelimb

    Marcus G. Pandy

    2008-05-01

    Full Text Available The equine distal forelimb is a common location of injuries related to mechanical overload. In this study, a two-dimensional model of the musculoskeletal system of the region was developed and applied to kinematic and kinetic data from walking and trotting horses. The forces in major tendons and joint reaction forces were calculated. The components of the joint reaction forces caused by wrapping of tendons around sesamoid bones were found to be of similar magnitude to the reaction forces between the long bones at each joint. This finding highlighted the importance of taking into account muscle-tendon wrapping when evaluating joint loading in the equine distal forelimb.

  14. Interconnection between critical flow rate and reaction force at discharge of boiling liquid coolant

    An analytical relationship enabling to determine reaction force at discharge of boiling liquid coolant by known critical flow rate and deceleration parameters is derived on the basis of the system of integral conservation equations. The formula is applicable both to critical and subcritical conditions of the discharge of dropping liquids, gases and two-phase mixtures through cylindrical flanges of different inlet geometry. Comparison with experimental data (deceleration pressure of 0.1-15 MPa, channel diameter of 0.82-97.1 mm, initial underheating of 0-100K, initial mass steam content of 0-1, reaction force of 2.5-5x104 N) shows good agreement. A conclusion is made that the derived dependences correctly account for the effect of scale factor and can be used for calculating emergency and transient conditions in nuclear power plants

  15. Atomic force microscope based Kelvin probe measurements : application to an electrochemical reaction

    Böhmisch, Mathias; Burmeister, Frank; Rettenberger, Armin; Zimmermann, Jörg; Boneberg, Johannes; Leiderer, Paul

    1997-01-01

    An atomic force microscope (AFM) was utilized as a Kelvin probe to determine work functions of several metals and semiconductors quantitarively. Most of the experimental data show excellent agreement with published values measured by photoemission. Variations in work functions as low as 5 mV could be detected with a typical lateral resolution of 20 nm. This method allowed us to analyze and explain the energetics of an electrochemical reaction on the surface of WSe2, which could be in situ ind...

  16. Experimental study of pipe reaction force and jet impingement load at the pipe break

    In the design of a light-water reactor nuclear power plant, the extreme loads which are caused as the result of hypothetical pipe break accident have recently become the most severe factors for the structure and equipment design of the plant. In this paper, we describe the results of experiments about reaction forces and jet impingement loads in the pipe break accident conditions. Experiments were carried out for the kinds of jets, that is steam jet and subcooled water jet. (orig.)

  17. Reaction Force Control of a Linear Electrical Generator for Direct Drive Wave Energy Conversion

    Shek, J.K.H.; Macpherson, D.E.; Mueller, M.A.; Xiang, J.

    2007-01-01

    Direct drive wave energy converters have been proposed in view of the disadvantage of mechanical complexity and low conversion efficiencies in conventional wave energy converters. By directly coupling a linear generator to a reciprocating wave energy device, it is suggested that direct drive power take-off could be a viable alternative to hydraulic- and pneumatic-based systems. To further realise the benefits of a direct drive system, a control scheme based on reaction force control to maximi...

  18. Trends in Ground-State Entropies for Transition Metal Based Hydrogen Atom Transfer Reactions

    Mader, Elizabeth A.; Manner, Virginia W.; Markle, Todd F.; Wu, Adam; Franz, James A.; Mayer, James M.

    2009-03-10

    Reported herein are thermochemical studies of hydrogen atom transfer (HAT) reactions involving transition metal H-atom donors MIILH and oxyl radicals. [FeII(H2bip)3]2+, [FeII(H2bim)3]2+, [CoII(H2bim)3]2+ and RuII(acac)2(py-imH) [H2bip = 2,2’-bi-1,4,5,6-tetrahydro¬pyrimidine, H2bim = 2,2’-bi-imidazoline, acac = 2,4-pentandionato, py-imH = 2-(2’-pyridyl)¬imidazole)] each react with TEMPO (2,2,6,6-tetramethyl-1-piperidinoxyl) or tBu3PhO• (2,4,6-tri-tert-butylphenoxyl) to give the deprotonated, oxidized metal complex MIIIL, and TEMPOH or tBu3PhOH. Solution equilibrium measurements for the reactions of Co and Fe complexes with TEMPO show a large, negative ground-state entropy for hydrogen atom transfer: ΔSºHAT = -30 ± 2 cal mol-1 K-1 for the two iron complexes and -41 ± 2 cal mol-1 K-1 for [CoII(H2bim)3]2+. The ΔSºHAT for TEMPO + RuII(acac)2(py-imH) is much closer to zero, 4.9 ± 1.1 cal mol-1 K-1. Calorimetric measurements quantitatively confirm the enthalpy of reaction for [FeII(H2bip)3]2+ + TEMPO, thus also confirming ΔSºHAT. Calorimetry on TEMPOH + tBu3PhO• gives ΔHºHAT = 11.2 ± 0.5 kcal mol-1 which matches the enthalpy predicted from the difference in literature solution BDEs. An evaluation of the literature BDEs of both TEMPOH and tBu3PhOH is briefly presented and new estimates are included on the relative enthalpy of solvation for tBu3PhO• vs. tBu3PhOH. The primary contributor to the large magnitude of the ground-state entropy |ΔSºHAT| for the metal complexes is vibrational entropy, ΔSºvib. The common assumption that ΔSºHAT ≈ 0 for HAT reactions, developed for organic and small gas phase molecules, does not hold for transition metal based HAT reactions. The trend in magnitude of |ΔSºHAT| for reactions with TEMPO, RuII(acac)2(py-imH) << [FeII(H2bip)3]2+ = [FeII(H2bim)3]2+ < [CoII(H2bim)3]2+, is surprisingly well predicted by the trends for electron transfer half-reaction entropies, ΔSºET, in aprotic solvents. ΔSºET and

  19. The gravitational radiation reaction force of a continuous medium. I. Perturbation of a quasi-newtonian motion

    We determine, within the general theory of relativity, the equations of motion in the slow approximation of a continuous medium in which the forces from material stresses do not play a leading part with respect to the gravitational forces. The gravitational radiation reaction force appears as a disturbing force in the post-post-newtonian equations of motion. Then, we deduce the formula for the variation of the energy of the system due to the gravitational radiation

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

    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)

  1. Role of radiation reaction forces in the dynamics of centrifugally accelerated particles

    In this paper we study the influence of radiation reaction (RR) forces on the dynamics of centrifugally accelerated particles. It is assumed that the particles move along magnetic field lines anchored in the rotating central object. The common 'bead-on-the-wire' approximation is used. The solutions are found and analyzed for cases when the form of the prescribed trajectory (rigidly rotating field line) is approximated by: (a) straight line, and (b) Archimedes spiral. Dynamics of neutral and charged particles are compared with the emphasis on the role of RR forces in the latter case. It is shown that for charged particles there exist locations of stable equilibrium. It is demonstrated that for particular initial conditions RR forces cause centripetal motion of the particles: their 'falling' on the central rotating object. It is found that in the case of Archimedes spiral both neutral and charged particles can reach infinity where their motion has asymptotically force-free character. The possible importance of these processes for the acceleration of relativistic, charged particles by rotating magnetospheres in the context of the generation of nonthermal, high-energy emission of AGN and pulsars is discussed

  2. Force.

    Gamble, Reed

    1989-01-01

    Discusses pupil misconceptions concerning forces. Summarizes some of Assessment of Performance Unit's findings on meaning of (1) force, (2) force and motion in one dimension and two dimensions, and (3) Newton's second law. (YP)

  3. Force Limiting Vibration Tests Evaluated from both Ground Acoustic Tests and FEM Simulations of a Flight Like Vehicle System Assembly

    Smith, Andrew; LaVerde, Bruce; Waldon, James; Hunt, Ron

    2014-01-01

    Marshall Space Flight Center has conducted a series of ground acoustic tests with the dual goals of informing analytical judgment, and validating analytical methods when estimating vibroacoustic responses of launch vehicle subsystems. The process of repeatedly correlating finite element-simulated responses with test-measured responses has assisted in the development of best practices for modeling and post-processing. In recent work, force transducers were integrated to measure interface forces at the base of avionics box equipment. Other force data was indirectly measured using strain gauges. The combination of these direct and indirect force measurements has been used to support and illustrate the advantages of implementing the Force Limiting approach for equipment qualification tests. The comparison of force response from integrated system level tests to measurements at the same locations during component level vibration tests provides an excellent illustration. A second comparison of the measured response cases from the system level acoustic tests to finite element simulations has also produced some principles for assessing the suitability of Finite Element Models (FEMs) for making vibroacoustics estimates. The results indicate that when FEM models are employed to guide force limiting choices, they should include sufficient detail to represent the apparent mass of the system in the frequency range of interest.

  4. Intervertebral reaction force prediction using an enhanced assembly of OpenSim models.

    Senteler, Marco; Weisse, Bernhard; Rothenfluh, Dominique A; Snedeker, Jess G

    2016-01-01

    OpenSim offers a valuable approach to investigating otherwise difficult to assess yet important biomechanical parameters such as joint reaction forces. Although the range of available models in the public repository is continually increasing, there currently exists no OpenSim model for the computation of intervertebral joint reactions during flexion and lifting tasks. The current work combines and improves elements of existing models to develop an enhanced model of the upper body and lumbar spine. Models of the upper body with extremities, neck and head were combined with an improved version of a lumbar spine from the model repository. Translational motion was enabled for each lumbar vertebrae with six controllable degrees of freedom. Motion segment stiffness was implemented at lumbar levels and mass properties were assigned throughout the model. Moreover, body coordinate frames of the spine were modified to allow straightforward variation of sagittal alignment and to simplify interpretation of results. Evaluation of model predictions for level L1-L2, L3-L4 and L4-L5 in various postures of forward flexion and moderate lifting (8 kg) revealed an agreement within 10% to experimental studies and model-based computational analyses. However, in an extended posture or during lifting of heavier loads (20 kg), computed joint reactions differed substantially from reported in vivo measures using instrumented implants. We conclude that agreement between the model and available experimental data was good in view of limitations of both the model and the validation datasets. The presented model is useful in that it permits computation of realistic lumbar spine joint reaction forces during flexion and moderate lifting tasks. The model and corresponding documentation are now available in the online OpenSim repository. PMID:26031341

  5. Impact of walking speed and slope of the ground on axial force of poles in Nordic walking

    Martin Pšurný

    2013-09-01

    Full Text Available BACKGROUND: Nordic walking (NW, due to its attractiveness and convenience of equipment, is becoming more popular and utilised in the areas of sports, recreation and physiotherapy. Some of its impacts on load to the body have not yet been sufficiently explored. OBJECTIVE: The objective of the study was to determine the impact of walking speed and slope of the ground on the magnitude of axial forces, transferred to the poles by upper extremities during NW. METHODS: The study was participated in by 17 healthy subjects, aged 25.9 ± 3.6 years, who went through 12 independent measurements on a treadmill in various speeds (6.0; 6.6; 7.2 and 7.8 km • h–1 and slopes (0; 5 and 7.5%. These measurements provided us with values of basic spatiotemporal variables, characterizing NW performance and force variables, acting on the poles. RESULTS: Increased walking speed led to increase in cycle frequency (p < .001 and increase in peak poling force and average poling force (p < .001. Poling time reduced with increasing speed (p < .001. Increase in slope of ground had no significant impact on the magnitude of time and dynamic variables. CONCLUSIONS: Increased walking speed during NW increases the force, generated by the upper extremities on the poles. During NW it is possible to prefer walking speed rather than to change the slope of the ground for those patients, who are indicated to strengthen upper extremities.

  6. The Effect of Mechanical Vibration Stimulation of Perception Subthreshold on the Muscle Force and Muscle Reaction Time of Lower Leg

    Kim, Huigyun; Kwak, Kiyoung; Kim, Dongwook

    2016-01-01

    The objective of this study is to investigate the effect of mechanical vibration stimulation on the muscle force and muscle reaction time of lower leg according to perception threshold and vibration frequency. A vibration stimulation with perception threshold intensity was applied on the Achilles tendon and tibialis anterior tendon. EMG measurement and analysis system were used to analyze the change of muscle force and muscle reaction time according to perception threshold and vibration frequ...

  7. Optimizing the third-and-a-half post-Newtonian gravitational radiation-reaction force for numerical simulations

    The gravitational radiation-reaction force acting on perfect fluids at 3.5 post-Newtonian order is cast into a form which is directly applicable to numerical simulations. Extensive use is made of metric-coefficient changes induced by functional coordinate transformations, of the continuity equation, as well as of the equations of motion. We also present an expression appropriate for numerical simulations of the radiation field causing the worked out reaction force

  8. Referral of tactile stimuli to action points in virtual reality with reaction force.

    Moizumi, Shunjiro; Yamamoto, Shinya; Kitazawa, Shigeru

    2007-09-01

    When we touch something with a tool, we feel the touch at the tip of the tool rather than at the hand. Yamamoto and Kitazawa [Yamamoto, S., Kitazawa, S., 2001b. Sensation at the tips of invisible tools. Nat. Neurosci. 4, 979-980] previously showed that the judgment of the temporal order of two successive stimuli, delivered to the tips of sticks held in each hand, was dramatically altered by crossing the sticks without changing the positions of the hands. This provided evidence for the referral of tactile signals to the tip of a tool in hand. In this study, we examined importance of force feedback from the tool in the referral by manipulating the direction of force feedback in a virtual reality. The virtual tool consisted of a spherical action point that was moved with a stylus in hand. Subjects held two styli, one in each hand, put each action point on each of two buttons in the virtual reality, and were required to judge the order of successive taps, delivered to the two styli. We manipulated the direction of reaction force from each button so that it was congruent or incongruent to the visual configuration of the button. When the arms were uncrossed, judgment primarily depended on whether the action points were crossed or not in the visual space. But when the arms were crossed, judgment critically depended on the direction of force feedback. The results show that tactile signals can be referred to the action point in the virtual reality and that the force feedback becomes a critical factor when the arms are crossed. PMID:17617482

  9. Ground Reaction Force Differences in the Countermovement Jump in Girls with Different Levels of Performance

    Floría, Pablo; Harrison, Andrew J.

    2013-01-01

    Purpose: The aim of this study was to ascertain the biomechanical differences between better and poorer performers of the vertical jump in a homogeneous group of children. Method: Twenty-four girls were divided into low-scoring (LOW; M [subscript age] = 6.3 ± 0.8 years) and high-scoring (HIGH; M [subscript age] = 6.6 ± 0.8 years) groups based on…

  10. Ground Reaction Forces and Plantar Pressure Distribution Generated by Two Tai Chi Movements

    Wong, Shiu Hong Trevor

    2013-01-01

    Tai Chi Chuan, Tai Chi (TC) in short, is a popular form of Chinese martial arts which have been practised by millions of people and provides various health benefits, such as improving balance control, strengthening leg muscles, reducing fear of falling, enhancing flexibility and many more. The American Geriatrics Society and the British Geriatrics Society have recommended TC as a suitable exercise for preventing falls of older people. However, it is not clear which TC components are the most ...

  11. The ground state of medium-heavy nuclei with non central forces

    A. FabrociniINFN and Phys.Dept., Univ.of Pisa, Pisa, Italy

    1997-01-01

    We study microscopically the ground state properties of 16O and 40Ca nuclei within correlated basis function theory. A truncated version of the realistic Urbana v14 (U14) potential, without momentum dependent terms, is adopted with state dependent correlations having spin, isospin and tensor components. Fermi hypernetted chain integral equations and single operator chain approximation are used to evaluate one- and two-body densities and ground state energy. The results are i...

  12. [Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio]. Volume 5, Field Investigation report

    1992-03-01

    An environmental investigation of ground water conditions has been undertaken at Wright-Patterson Air Force Base (WPAFB), Ohio to obtain data to assist in the evaluation of a potential removal action to prevent, to the extent practicable, migration of the contaminated ground water across Base boundaries. Field investigations were limited to the central section of the southwestern boundary of Area C and the Springfield Pike boundary of Area B. Further, the study was limited to a maximum depth of 150 feet below grade. Three primary activities of the field investigation were: (1) installation of 22 monitoring wells, (2) collection and analysis of ground water from 71 locations, (3) measurement of ground water elevations at 69 locations. Volatile organic compounds including trichloroethylene, perchloroethylene, and/or vinyl chloride were detected in concentrations exceeding Maximum Contaminant Levels (MCL) at three locations within the Area C investigation area. Ground water at the Springfield Pike boundary of Area B occurs in two primary units, separated by a thicker-than-expected clay layers. One well within Area B was determined to exceed the MCL for trichloroethylene.

  13. A theoretical investigation of ground effects on USB configurations

    Lan, C. E.

    1979-01-01

    A formulation predicts the variation of circulation forces and jet reaction forces in ground proximity as a function of ground height. The predicted results agree well with available experimental data. It is shown that the wing-alone theory is not capable of predicting the ground effect for USB configurations.

  14. Reaction forces due to the decompression of pressurized vessels filled with two-phase fluids

    A unique fluid behavioral model which is applicable to many homogeneous multiphase fluids is used as a generic model to examine the reaction forces developed by the decompression of pressurized vessels filled with single component two-phase fluids. The decompression is the result of the sudden creation of an outflow area such as by the accidental puncture of the vessel shell or the rupture of a pipe connection at the vessel. The study includes the treatment of two basic initial conditions: the case of a vessel completely filled with a saturated liquid, and the case of a vessel partially filled with a saturated liquid and covered with its saturated vapor, that is, the two region stratified condition. The principal variables include an expansion parameter which characterizes the fluid behavior in the two-phase domain, the vapor volume fraction, and the location of the outflow area for the stratified case

  15. [Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio]. Volume 9, Removal action system design

    1992-04-01

    This Removal Action System Design has been prepared as a Phase I Volume for the implementation of the Phase II removal action at Wright-Patterson Air Force Base (WPAFB) near Dayton, Ohio. The objective of the removal action is to prevent, to the extent practicable, the migration of ground water contaminated with chlorinated volatile organic compounds (VOCS) across the southwest boundary of Area C. The Phase 1, Volume 9 Removal Action System Design compiles the design documents prepared for the Phase II Removal Action. These documents, which are presented in Appendices to Volume 9, include: Process Design, which presents the 30 percent design for the ground water treatment system (GWTS); Design Packages 1 and 2 for Earthwork and Road Construction, and the Discharge Pipeline, respectively; no drawings are included in the appendix; Design Package 3 for installation of the Ground Water Extraction Well(s); Design Package 4 for installation of the Monitoring Well Instrumentation; and Design Package 5 for installation of the Ground Water Treatment System; this Design Package is incorporated by reference because of its size.

  16. Simulation of (p,d) reaction on RIBLL2 for study of tensor force

    郭晨雷; 张高龙; 屈卫卫; Satoru Terashim; Isao Tanihat; 乐小云

    2015-01-01

    In order to study the effect of tensor force, we plan to perform a (p,d) reaction with a 400–1600 MeV proton beam on the RIBLL2 at Lanzhou. Based on the experimental conditions of RIBLL2, a Monte Carlo method is used to simulate (p,d) reaction process. The distributions of primary beam and scattered deuterons are given on the target and at the F1, F2, F3, and F4 positions. Considering the yield of the deuteron, to separate the produced deuteron from the background particles, the target thickness is optimized. To obtain a clear particle identification spectrum by time of fl ight (TOF) and energy loss (∆E ), the distance between the two detectors, as well as the energy and timing resolution of detectors are simulated. As a result, the distance between F2 and F4 is fit for that of TOF. After taking into account the particle distribution at F4, both sizes of Multi-Wire Drift Chamber, namely MWDC2 and MWDC3, are selected to be 50 mm × 50 mm.

  17. [Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio]. Volume 5, Appendix A, Part 1, Field Investigation report

    1992-03-01

    This report presents information related to the sampling of ground water at the Wright-Patterson Air Force Base. It is part of an investigation into possible ground water contamination. Information concerns well drilling/construction; x-ray diffraction and sampling; soil boring logs; and chain-of-custody records.

  18. Grounding the Lexical Semantics of Verbs in Visual Perception using Force Dynamics and Event Logic

    Siskind, J M

    2011-01-01

    This paper presents an implemented system for recognizing the occurrence of events described by simple spatial-motion verbs in short image sequences. The semantics of these verbs is specified with event-logic expressions that describe changes in the state of force-dynamic relations between the participants of the event. An efficient finite representation is introduced for the infinite sets of intervals that occur when describing liquid and semi-liquid events. Additionally, an efficient procedure using this representation is presented for inferring occurrences of compound events, described with event-logic expressions, from occurrences of primitive events. Using force dynamics and event logic to specify the lexical semantics of events allows the system to be more robust than prior systems based on motion profile.

  19. Grounding the Lexical Semantics of Verbs in Visual Perception using Force Dynamics and Event Logic

    Siskind, J. M.

    2011-01-01

    This paper presents an implemented system for recognizing the occurrence of events described by simple spatial-motion verbs in short image sequences. The semantics of these verbs is specified with event-logic expressions that describe changes in the state of force-dynamic relations between the participants of the event. An efficient finite representation is introduced for the infinite sets of intervals that occur when describing liquid and semi-liquid events. Additionally, an efficient proced...

  20. Mechanics of Ship Grounding

    Pedersen, Preben Terndrup

    1996-01-01

    In these notes first a simplified mathematical model is presented for analysis of ship hull loading due to grounding on relatively hard and plane sand, clay or rock sea bottoms. In a second section a more rational calculation model is described for the sea bed soil reaction forces on the sea bott...

  1. Force and Torque Analytical Models of a Reaction Sphere Actuator Based on Spherical Harmonic Rotation and Decomposition

    Rossini, L.; Chetelat, O.; Onillon, E.; Perriard, Y.

    2013-01-01

    This paper presents an analytical model for the force and torque developed by a reaction sphere actuator for satellite attitude control. The reaction sphere is an innovative momentum exchange device consisting of a magnetic bearings spherical rotor that can be electronically accelerated in any direction making all the three axes of stabilized spacecrafts controllable by a unique device. The spherical actuator is composed of an 8-pole permanent magnet spherical rotor and of a 20-coil stator. F...

  2. Coupling Satellite and Ground-Based Instruments to Map Climate Forcing by Anthropogenic Aerosols

    Charlson, Robert J.; Anderson, Theodore L.; Hostetler, Chris (Technical Monitor)

    2000-01-01

    Climate forcing by anthropogenic aerosols is a significant but highly uncertain factor in global climate change. Only satellites can offer the global coverage essential to reducing this uncertainty; however, satellite measurements must be coupled with correlative, in situ measurements both to constrain the aerosol optical properties required in satellite retrieval algorithms and to provide chemical identification of aerosol sources. This grant funded the first two years of a three-year project which seeks to develop methodologies for combining spaceborne lidar with in-situ aerosol data sets to improve estimates of direct aerosol climate forcing. Progress under this two-year grant consisted in the development and deployment of a new in-situ capability for measuring aerosol 180' backscatter and the extinction-to-backscatter ratio. This new measurement capacity allows definitive lidar/in-situ comparisons and improves our ability to interpret lidar data in terms of climatically relevant quantities such as the extinction coefficient and optical depth. Measurements were made along the coast of Washington State, in Central Illinois, over the Indian Ocean, and in the Central Pacific. Thus, this research, combined with previous measurements by others, is rapidly building toward a global data set of extinction-to-backscatter ratio for key aerosol types. Such information will be critical to interpreting lidar data from the upcoming PICASSO-CENA, or P-C, satellite mission. Another aspect of this project is to investigate innovative ways to couple the lidar-satellite signal with targeted in-situ measurements toward a direct determination of aerosol forcing. This aspect is progressing in collaboration with NASA Langley's P-C lidar simulator and radiative transfer modeling by the University of Lille, France.

  3. The Effect of Mechanical Vibration Stimulation of Perception Subthreshold on the Muscle Force and Muscle Reaction Time of Lower Leg

    Kim, Huigyun; Kwak, Kiyoung; Kim, Dongwook

    2016-01-01

    The objective of this study is to investigate the effect of mechanical vibration stimulation on the muscle force and muscle reaction time of lower leg according to perception threshold and vibration frequency. A vibration stimulation with perception threshold intensity was applied on the Achilles tendon and tibialis anterior tendon. EMG measurement and analysis system were used to analyze the change of muscle force and muscle reaction time according to perception threshold and vibration frequency. A root-mean-square (RMS) value was extracted using analysis software and Maximum Voluntary Contraction (MVC) and Premotor Time (PMT) were analyzed. The measurement results showed that perception threshold was different from application sites of vibration frequency. Also, the muscle force and muscle reaction time showed difference according to the presence of vibration, frequency, and intensity. This result means that the vibration stimulation causes the change on the muscle force and muscle reaction time and affects the muscles of lower leg by the characteristics of vibration stimulation. PMID:27382244

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

    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.

  5. Use of aquifer testing to complete ground water remedial design, shallow aquifer Nellis Air Force Base, Las Vegas, Nevada

    As part of a US Army Corps of Engineers-directed remedial action, a ground water treatment system is being installed at Site 27, Nellis Air Force Base, Las Vegas, Nevada. Twenty-three extraction wells were installed in the center and on the leading edge of a jet fuel plume of free and dissolved product in the uppermost (nonpotable) aquifer. The purpose of the extraction well system is to contain and remediate the plume, and to recover free product, which is over 10 feet thick in one well. Aquifer testing, including step and constant discharge tests, was conducted during well installation in order to (1) assist in location of subsequent wells, (2) obtain dynamic product thickness data for selection of wells in which skimmer pumps will be installed, (3) determine initial pumping rates, (4) determine aquifer parameters for modeling and optimization, and (5) provide baseline data on well performance to evaluate possible future biofouling

  6. [Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio]. Volume 1, Site assessment report

    1991-10-01

    In April 1990, Wright-Patterson Air Force Base (WPAFB) initiated an effort for the evaluation of potential removal of ground water contamination at the Base. This report presents a current assessment of the nature and extent of the contamination believed to be migrating across the southwestern boundary of Area C and the northern boundary of Area B based upon analysis of existing environmental data obtained from several sources. The existing data base indicates widespread, low-level contamination moving across Base boundaries at levels that pose no immediate threat to the Mad River Valley well fields. An investigation by the City of Dayton in May and June 1990, however, implies that a more identifiable plume of PCE and TCE may be crossing the southwestern boundary of Area C immediately downgradient of Landfill 5. More data is needed to delineate ground water contamination and to design and implement a suitable control system. This report concludes that although an extensive study of the boundaries in question would be the preferred approach, a limited, focused investigation and subsequent feasibility study can be accomplished with a reasonable certainty of achieving the desired outcome of this project.

  7. The law of action and reaction for the effective force in a non-equilibrium colloidal system

    We study a non-equilibrium Langevin many-body system containing two 'test' particles and many 'background' particles. The test particles are spatially confined by a harmonic potential, and the background particles are driven by an external driving force. Using numerical simulations of the model, we formulate an effective description of the two test particles in a non-equilibrium steady state. In particular, we investigate several different definitions of the effective force acting between the test particles. We find that the law of action and reaction does not hold for the total mechanical force exerted by the background particles, but that it does hold for the thermodynamic force defined operationally on the basis of an idea used to extend the first law of thermodynamics to non-equilibrium steady states

  8. Toward Determining ATPase Mechanism in ABC Transporters: Development of the Reaction Path–Force Matching QM/MM Method

    Zhou, Y.; Ojeda-May, P.; Nagaraju, M.; Pu, J.

    2016-01-01

    Adenosine triphosphate (ATP)-binding cassette (ABC) transporters are ubiquitous ATP-dependent membrane proteins involved in translocations of a wide variety of substrates across cellular membranes. To understand the chemomechanical coupling mechanism as well as functional asymmetry in these systems, a quantitative description of how ABC transporters hydrolyze ATP is needed. Complementary to experimental approaches, computer simulations based on combined quantum mechanical and molecular mechanical (QM/MM) potentials have provided new insights into the catalytic mechanism in ABC transporters. Quantitatively reliable determination of the free energy requirement for enzymatic ATP hydrolysis, however, requires substantial statistical sampling on QM/MM potential. A case study shows that brute force sampling of ab initio QM/MM (AI/MM) potential energy surfaces is computationally impractical for enzyme simulations of ABC transporters. On the other hand, existing semiempirical QM/MM (SE/MM) methods, although affordable for free energy sampling, are unreliable for studying ATP hydrolysis. To close this gap, a multiscale QM/MM approach named reaction path–force matching (RP–FM) has been developed. In RP–FM, specific reaction parameters for a selected SE method are optimized against AI reference data along reaction paths by employing the force matching technique. The feasibility of the method is demonstrated for a proton transfer reaction in the gas phase and in solution. The RP–FM method may offer a general tool for simulating complex enzyme systems such as ABC transporters. PMID:27498639

  9. Toward Determining ATPase Mechanism in ABC Transporters: Development of the Reaction Path-Force Matching QM/MM Method.

    Zhou, Y; Ojeda-May, P; Nagaraju, M; Pu, J

    2016-01-01

    Adenosine triphosphate (ATP)-binding cassette (ABC) transporters are ubiquitous ATP-dependent membrane proteins involved in translocations of a wide variety of substrates across cellular membranes. To understand the chemomechanical coupling mechanism as well as functional asymmetry in these systems, a quantitative description of how ABC transporters hydrolyze ATP is needed. Complementary to experimental approaches, computer simulations based on combined quantum mechanical and molecular mechanical (QM/MM) potentials have provided new insights into the catalytic mechanism in ABC transporters. Quantitatively reliable determination of the free energy requirement for enzymatic ATP hydrolysis, however, requires substantial statistical sampling on QM/MM potential. A case study shows that brute force sampling of ab initio QM/MM (AI/MM) potential energy surfaces is computationally impractical for enzyme simulations of ABC transporters. On the other hand, existing semiempirical QM/MM (SE/MM) methods, although affordable for free energy sampling, are unreliable for studying ATP hydrolysis. To close this gap, a multiscale QM/MM approach named reaction path-force matching (RP-FM) has been developed. In RP-FM, specific reaction parameters for a selected SE method are optimized against AI reference data along reaction paths by employing the force matching technique. The feasibility of the method is demonstrated for a proton transfer reaction in the gas phase and in solution. The RP-FM method may offer a general tool for simulating complex enzyme systems such as ABC transporters. PMID:27498639

  10. 3D FEM Numerical Simulation of Seismic Pile-supported Bridge Structure Reaction in Liquefying Ground

    Ling XianZhang, Tang Liang and Xu Pengju

    2011-04-01

    Full Text Available This study examines the establishment of liquefied ground pile-soil-bridge seismic interaction analysis of three-dimensional finite element analysis method for the simulation of liquefied ground shaking table test of pile-soil seismic interaction analysis, undertake OpenSees finite element based numerical simulation platform, for the shaking table test based on two-phase saturated porous media, Comparative numerical and experimental results, detailed test pile dynamic response of bridge structure and dynamic properties, especially liquefaction pore pressure, liquefaction of pile foundation and the dynamic response of the free field. Finite element method can reasonably predict the site of pore pressure, dynamic response; despite the conventional beam element simulation of pile, pile dynamic response can still accurately simulated.

  11. Guiding-centre transformation of the radiation-reaction force in a non-uniform magnetic field

    Hirvijoki, E.; Decker, J.; Brizard, A. J.; Embréus, O.

    2015-10-01

    > In this paper, we present the guiding-centre transformation of the radiation-reaction force of a classical point charge travelling in a non-uniform magnetic field. The transformation is valid as long as the gyroradius of the charged particles is much smaller than the magnetic field non-uniformity length scale, so that the guiding-centre Lie-transform method is applicable. Elimination of the gyromotion time scale from the radiation-reaction force is obtained with the Poisson-bracket formalism originally introduced by Brizard (Phys. Plasmas, vol. 11, 2004, 4429-4438), where it was used to eliminate the fast gyromotion from the Fokker-Planck collision operator. The formalism presented here is applicable to the motion of charged particles in planetary magnetic fields as well as in magnetic confinement fusion plasmas, where the corresponding so-called synchrotron radiation can be detected. Applications of the guiding-centre radiation-reaction force include tracing of charged particle orbits in complex magnetic fields as well as the kinetic description of plasma when the loss of energy and momentum due to radiation plays an important role, e.g. for runaway-electron dynamics in tokamaks.

  12. Russian Military and Security Forces: A Postulated Reaction to a Nuclear Detonation

    Ball, D

    2005-04-29

    In this paper, we will examine how Russia's military and security forces might react to the detonation of a 10-kiloton nuclear weapon placed next to the walls surrounding the Kremlin. At the time of this 'big bang,' Putin is situated outside Moscow and survives the explosion. No one claims responsibility for the detonation. No other information is known. Numerous variables will determine how events ultimately unfold and how the military and security forces will respond. Prior to examining these variables in greater detail, it is imperative to elucidate first what we mean by Russia's military and security forces.

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

    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. PMID:24959612

  14. The law of action and reaction for the effective force in a nonequilibrium colloidal system

    Hayashi, Kumiko; Sasa, Shin-ichi

    2005-01-01

    We study a nonequilibrium Langevin many-body system containing two 'test' particles and many 'background' particles. The test particles are spatially confined by a harmonic potential, and the background particles are driven by an external driving force. Employing numerical simulations of the model, we formulate an effective description of the two test particles in a nonequilibrium steady state. In particular, we investigate several different definitions of the effective force acting between t...

  15. Reassessment of psychological distress and post-traumatic stress disorder in United States Air Force Distributed Common Ground System operators.

    Prince, Lillian; Chappelle, Wayne L; McDonald, Kent D; Goodman, Tanya; Cowper, Sara; Thompson, William

    2015-03-01

    The goal of this study was to assess for the main sources of occupational stress, as well as self-reported symptoms of distress and post-traumatic stress disorder among U.S. Air Force (USAF) Distributed Common Ground System (DCGS) intelligence exploitation and support personnel. DCGS intelligence operators (n=1091) and nonintelligence personnel (n = 447) assigned to a USAF Intelligence, Surveillance, and Reconnaissance Wing responded to the web-based survey. The overall survey response rate was 31%. Study results revealed the most problematic stressors among DCGS intelligence personnel included high workload, low manning, as well as organizational leadership and shift work issues. Results also revealed 14.35% of DCGS intelligence operators' self-reported high levels of psychological distress (twice the rate of DCGS nonintelligence support personnel). Furthermore, 2.0% to 2.5% self-reported high levels of post-traumatic stress disorder symptoms, with no significant difference between groups. The implications of these findings are discussed along with recommendations for USAF medical and mental health providers, as well as operational leadership. PMID:25747649

  16. Measurement of the rates of reaction of the ground and metastable excited states of 02+, N0+ and 0+ with atmospheric gases at thermal energy

    Thermal-energy reaction rate coefficients and product ion distributions have been measured for reactions of both the ground state and metastable electronic states of 02+, N0+ and 0+ with several neutral species, using a selected-ion flow tube. In general the excited-ion reaction rates are fast, frequently approaching the Langevin limit. Collisional quenching occurs for the reactions of N0+sup(star) with N2,02 and H2 and the quenching rates have been determined. The ion source also provided a substantial yield of doubly charged 02 permitting some measurements of reaction rates of 022+. (author)

  17. Cluster emission in superdeformed Sr isotopes in the ground state and formed in heavy-ion reaction

    K P Santhosh; Antony Joseph

    2005-01-01

    Cluster decay of superdeformed 76,78,80Sr isotopes in their ground state are studied taking the Coulomb and proximity potential as the interacting barrier for the post-scission region. The predicted 1/2 values are found to be in close agreement with those values reported by the preformed cluster model (PCM). Our calculation shows that these nuclei are stable against both light and heavy cluster emissions. We studied the decay of these nuclei produced as an excited compound system in heavy-ion reaction. It is found that inclusion of excitation energy increases the decay rate (decreases 1/2 value) considerably and these nuclei become unstable against decay. These findings support earlier observation of Gupta et al based on PCM.

  18. Repulsion forces of superplasticizers on ground granulated blast furnace slag in alkaline media, from AFM measurements to rheological properties

    Palacios, M.

    2012-12-01

    Full Text Available The electrostatic and steric repulsion induced by different superplasticizers on ground granulated blast furnace slag in alkaline media have been studied. The superplasticizers were sulfonated naphthalene, sulfonated melamine, vinyl copolymer, and polycarboxylate- based admixtures. With these superplasticizers the slag suspensions had negative zeta potentials, ranging from -3 to -10 mV. For the first time the adsorbed layer thicknesses for superplasticizers on slag using colloidal probe atomic force microscopy has been measured. To model the interparticle force interactions an effective Hamaker constant was computed from dielectric properties measured on a dense slag sample produced by spark plasma sintering. The obtained results conclude that the dispersion mechanism for all the superplasticizers studied in the present work is mainly dominated by the steric repulsion. Results were then used in a yield stress model, YODEL, to predict the yield stress with and without the superplasticizers. Predictions of the yield stress agreed well with experimental results.

    En este trabajo se ha estudiado la repulsión electrostática y estérica inducida por diferentes aditivos superplastificantes en sistemas de escoria de horno alto en medios alcalinos. Se han estudiado aditivos superplastificantes basados en naftaleno, melamina, copolímeros vinílicos y basados en policarboxilato. Estos aditivos inducen en la escoria un potencial zeta negativo, entre -3 y -10 mV. Por primera vez, se ha determinado el grosor de la capa de aditivo adsorbido sobre la escoria mediante microscopía de fuerzas atómicas (AFM. Para modelizar las fuerzas de interacción entre partículas, se ha determinado la constante efectiva de Hamaker de la escoria a partir de las propiedades dieléctricas de una muestra de escoria obtenida mediante sinterización spark plasma sintering. Los resultados obtenidos concluyen que el mecanismo de dispersión de los superplastificantes

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

    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…

  20. Construction of cryptographic information protection in automated control systems for rapid reaction military forces

    Sergey Petrovich Evseev

    2012-04-01

    Full Text Available New approaches to realizations of military operations are analyzed. The main factors that directly affect the construction and operation of information security subsystems in prospective automated command and control military systems are described. Possible ways of the construction of cryptographic subsystems of information protection in automated operation management systems for united military force groups are investigated.

  1. Kinetic study of radiation-reaction-limited particle acceleration during the relaxation of unstable force-free equilibria

    Yuan, Yajie; Zrake, Jonathan; East, William E; Blandford, Roger D

    2016-01-01

    Many powerful and variable gamma-ray sources, including pulsar wind nebulae, active galactic nuclei and gamma-ray bursts, seem capable of accelerating particles to gamma-ray emitting energies efficiently over very short time scales. These are likely due to rapid dissipation of electromagnetic energy in a highly magnetized, relativistic plasma. In order to understand the generic features of such processes, we have investigated simple models based on relaxation of unstable force-free magnetostatic equilibria. In this work, we make the connection between the corresponding plasma dynamics and the expected radiation signal, using 2D particle-in-cell simulations that self-consistently include synchrotron radiation reaction. We focus on the lowest order unstable force-free equilibrium in a 2D periodic box. We find that rapid variability, with modest apparent radiation efficiency as perceived by a fixed observer, can be produced during the evolution of the instability. The "flares" are accompanied by an increased pol...

  2. Experimental Studies of the Coulomb Force Effects in Deuteron-Proton Break-up Reaction at Medium Energy Regime

    Ciepał, I.; Parol, W.; Kalantar-Nayestanaki, N.; Khatri, G.; Kistryn, St.; Kłos, B.; Kozela, A.; Kulessa, P.; Messchendorp, J.; Skwira-Chalot, I.; Stephan, E.; Włoch, B.

    2016-03-01

    A set of differential cross-section data of the 1H(d, pp)n breakup reaction at 130 and 160 MeV deuteron beam energies has been measured in the forward polar angles domain. The data were collected with the use of the Germanium Wall (FZ Jülich) and BINA (KVI Groningen) detectors. This part of the phase-space is special with respect to the dominant Coulomb force influence on the system dynamics. The data are compared with the theoretical calculations based on the Argonne V18 potential supplemented with the long-range electromagnetic component. The predictions also include the Urbana IX three nucleon force model. The strongest Coulomb effects are found in regions where the relative energy of the two protons is the smallest.

  3. Kinetic Study of Radiation-reaction-limited Particle Acceleration During the Relaxation of Unstable Force-free Equilibria

    Yuan, Yajie; Nalewajko, Krzysztof; Zrake, Jonathan; East, William E.; Blandford, Roger D.

    2016-09-01

    Many powerful and variable gamma-ray sources, including pulsar wind nebulae, active galactic nuclei and gamma-ray bursts, seem capable of accelerating particles to gamma-ray emitting energies efficiently over very short timescales. These are likely due to the rapid dissipation of electromagnetic energy in a highly magnetized, relativistic plasma. In order to understand the generic features of such processes, we have investigated simple models based on the relaxation of unstable force-free magnetostatic equilibria. In this work, we make the connection between the corresponding plasma dynamics and the expected radiation signal, using 2D particle-in-cell simulations that self-consistently include synchrotron radiation reactions. We focus on the lowest order unstable force-free equilibrium in a 2D periodic box. We find that rapid variability, with modest apparent radiation efficiency as perceived by a fixed observer, can be produced during the evolution of the instability. The “flares” are accompanied by an increased polarization degree in the high energy band, with rapid variation in the polarization angle. Furthermore, the separation between the acceleration sites and the synchrotron radiation sites for the highest energy particles facilitates acceleration beyond the synchrotron radiation reaction limit. We also discuss the dynamical consequences of the radiation reaction, and some astrophysical applications of this model. Our current simulations with numerically tractable parameters are not yet able to reproduce the most dramatic gamma-ray flares, e.g., from the Crab Nebula. Higher magnetization studies are promising and will be carried out in the future.

  4. 基于足地接触力跟踪的单足机器人弹跳运动控制%Hopping Control of Single leg Robot on Compliant Ground Based on Ground Force Control

    尹鹏; 李满天; 王俊; 查富生; 孙立宁

    2015-01-01

    The performance of legged hopping robot is subjected to the influence of the ground stiffness feature during the contact phase.To avoid the influence and insulate the ground stiffness disturbance we first established the simplified single leg hopping model with elastic featured ground,then an analysis about the relation of ground stiffness with moving trajectory and contact force profile is made.Based on this a control strategy to utilized to compensate the ground contact force to be the same as that of an undisturbed system via active extension or retraction of the leg during contact.The validity is demonstrated by simulation result.%为了使足式弹跳机器人在运动中避免由于地面接触刚度的变化对弹跳运动产生的影响,首先建立了单足弹跳机器人在弹性地面条件下的运动简化模型,进而分析了地面弹簧刚度变化对机体重心运动轨迹以及着地相中足地接触力的影响。采用足地接触力补偿控制的手段,通过主动控制单腿的伸缩,使模型中弹簧系统的足力输出与期望保持一致,消除了地面刚度变化对机体运动的干扰。利用仿真实验表明了控制方法的可行性。

  5. [Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio]. Volume 2, Work plan: Phase 1, Task 4, Field Investigation: Draft

    1991-10-01

    In April 1990 Wright-Patterson Air Force Base (WPAFB) initiated an investigation to evaluate a potential CERCLA removal action to prevent, to the extent practicable, the migration of ground-water contamination in the Mad River Valley Aquifer within and across WPAFB boundaries. The action will be based on a Focused Feasibility Study with an Action Memorandum serving as a decision document that is subject to approval by the Ohio Environmental Protection Agency. The first phase (Phase 1) of this effort involves an investigation of ground-water contamination migrating across the southwest boundary of Area C and across Springfield Pike adjacent to Area B. Task 4 of Phase 1 is a field investigation to collect sufficient additional information to evaluate removal alternatives. The field investigation will provide information in the following specific areas of study: water-level data which will be used to permit calibration of the ground-water flow model to a unique time in history; and ground-water quality data which will be used to characterize the current chemical conditions of ground water.

  6. Multi-Level Wild Land Fire Fighting Management Support System for an Optimized Guidance of Ground and Air Forces

    Almer, Alexander; Schnabel, Thomas; Perko, Roland; Raggam, Johann; Köfler, Armin; Feischl, Richard

    2016-04-01

    Climate change will lead to a dramatic increase in damage from forest fires in Europe by the end of this century. In the Mediterranean region, the average annual area affected by forest fires has quadrupled since the 1960s (WWF, 2012). The number of forest fires is also on the increase in Central and Northern Europe. The Austrian forest fire database shows a total of 584 fires for the period 2012 to 2014, while even large areas of Sweden were hit by forest fires in August 2014, which were brought under control only after two weeks of intense fire-fighting efforts supported by European civil protection modules. Based on these facts, the improvements in forest fire control are a major international issue in the quest to protect human lives and resources as well as to reduce the negative environmental impact of these fires to a minimum. Within this paper the development of a multi-functional airborne management support system within the frame of the Austrian national safety and security research programme (KIRAS) is described. The main goal of the developments is to assist crisis management tasks of civil emergency teams and armed forces in disaster management by providing multi spectral, near real-time airborne image data products. As time, flexibility and reliability as well as objective information are crucial aspects in emergency management, the used components are tailored to meet these requirements. An airborne multi-functional management support system was developed as part of the national funded project AIRWATCH, which enables real-time monitoring of natural disasters based on optical and thermal images. Airborne image acquisition, a broadband line of sight downlink and near real-time processing solutions allow the generation of an up-to-date geo-referenced situation map. Furthermore, this paper presents ongoing developments for innovative extensions and research activities designed to optimize command operations in national and international fire

  7. Wave packet and statistical quantum calculations for the He + NeH{sup +} → HeH{sup +} + Ne reaction on the ground electronic state

    Koner, Debasish; Panda, Aditya N., E-mail: adi07@iitg.ernet.in [Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Barrios, Lizandra; González-Lezana, Tomás, E-mail: t.gonzalez.lezana@csic.es [Instituto de Física Fundamental, C.S.I.C., Serrano 123, Madrid 28006 (Spain)

    2014-09-21

    A real wave packet based time-dependent method and a statistical quantum method have been used to study the He + NeH{sup +} (v, j) reaction with the reactant in various ro-vibrational states, on a recently calculated ab initio ground state potential energy surface. Both the wave packet and statistical quantum calculations were carried out within the centrifugal sudden approximation as well as using the exact Hamiltonian. Quantum reaction probabilities exhibit dense oscillatory pattern for smaller total angular momentum values, which is a signature of resonances in a complex forming mechanism for the title reaction. Significant differences, found between exact and approximate quantum reaction cross sections, highlight the importance of inclusion of Coriolis coupling in the calculations. Statistical results are in fairly good agreement with the exact quantum results, for ground ro-vibrational states of the reactant. Vibrational excitation greatly enhances the reaction cross sections, whereas rotational excitation has relatively small effect on the reaction. The nature of the reaction cross section curves is dependent on the initial vibrational state of the reactant and is typical of a late barrier type potential energy profile.

  8. Driving forces and the influence of the buffer composition on the complexation reaction between ibuprofen and HPCD.

    Perlovich, German L; Skar, Merete; Bauer-Brandl, Annette

    2003-10-01

    Cyclodextrins are often used in order to increase the aqueous solubility of drug substances by complexation. In order to investigate the complexation reaction of ibuprofen and hydroxypropyl-beta-cyclodextrin, titration calorimetry was used as a direct method. The thermodynamic parameters of the complexation process (stability constant, K(11); complexation enthalpy, deltaH(c) degrees ) were obtained in two different buffer systems (citric acid/sodium-phosphate and phosphoric acid) at various pH values. Based on these data the relative contributions of the enthalpic and entropic terms of the Gibbs energy to the complexation process have been analyzed. In both buffers the enthalpic and entropic terms are of different sign and this case corresponds to a 'nonclassical' model of hydrophobic interaction. In citric buffer, the main driving force of complexation is the entropy, which increases from 60 to 67% while the pH of the solution increases from 3.2 to 8.0. However, for the phosphoric buffer the entropic term decreases from 60 to 45%, while the pH-value of the solution increases from 5.0 to 8.2, and the driving force of the complexation process changes from entropy to enthalpy. The experimental data of the present study are compared to results of other authors and discrepancies discussed in detail. PMID:14550885

  9. Comparative Finite Element Analysis of the Effects of Tillage Tool Geometry on Soil Disturbance and Reaction Forces

    Mohamed Ahmed Elbashir

    2014-04-01

    Full Text Available In this study a comparative finite element analysis was conducted to investigate the effects of tillage tool geometry on soil disturbance and reaction forces. A nonlinear three dimensional finite element model, using ANSYS software, was developed to study the soil cutting process by trapezoidal (T1 and rectangular (T2 flat tools that inclined to the horizontal at three rake angles (R1 = 30°, R2 = 60° and R3 = 90°, therefore a total of six treatments were considered in this analysis. The soil media was assumed as elastic-perfectly plastic material with Drucker-Prager’s model. Results of this study revealed that the maximum vertical soil displaced by T1 is greater than that of T2; hence T1 disturbed the soil better than T2 . Results also showed that a significant reduction in draft force was noticed when cutting the soil with T1 in comparison to T2 . Designing the tool in the form of T1 significantly reduces the surface area of the tool; thus conserving the engineering material.

  10. Kinematics and Ground Reaction Force Determination: A Demonstration Quantifying Locomotor Abilities of Young Adult, Middle-aged, and Geriatric Rats

    Webb, Aubrey A.; Kerr, Brendan; Neville, Tanya; Ngan, Sybil; Assem, Hisham

    2011-01-01

    Behavior, in its broadest definition, can be defined as the motor manifestation of physiologic processes. As such, all behaviors manifest through the motor system. In the fields of neuroscience and orthopedics, locomotion is a commonly evaluated behavior for a variety of disease models. For example, locomotor recovery after traumatic injury to the nervous system is one of the most commonly evaluated behaviors 1-3. Though locomotion can be evaluated using a variety of endpoint measurements (e....

  11. [Environmental investigation of ground water contamination at Wright- Patterson Air Force Base, Ohio]. Volume 4, Health and Safety Plan (HSP); Phase 1, Task 4 Field Investigation report: Draft

    1991-10-01

    This Health and Safety Plan (HSP) was developed for the Environmental Investigation of Ground-water Contamination Investigation at Wright-Patterson Air Force Base near Dayton, Ohio, based on the projected scope of work for the Phase 1, Task 4 Field Investigation. The HSP describes hazards that may be encountered during the investigation, assesses the hazards, and indicates what type of personal protective equipment is to be used for each task performed. The HSP also addresses the medical monitoring program, decontamination procedures, air monitoring, training, site control, accident prevention, and emergency response.

  12. [Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio]. Volume 3, Appendix A, Draft standard operating procedures and elements: Sampling and Analysis Plan (SAP): Phase 1, Task 4, Field Investigation, Draft

    1991-10-01

    This report presents information concerning field procedures employed during the monitoring, well construction, well purging, sampling, and well logging at the Wright-Patterson Air Force Base. Activities were conducted in an effort to evaluate ground water contamination.

  13. Repulsion forces of superplasticizers on ground granulated blast furnace slag in alkaline media, from AFM measurements to rheological properties

    Palacios, M.; Bowen, P.; Kappl, M.; Butt, H. J.; Stuer, M; Pecharromán, C.; Aschauer, U.; Puertas, F.

    2012-01-01

    The electrostatic and steric repulsion induced by different superplasticizers on ground granulated blast furnace slag in alkaline media have been studied. The superplasticizers were sulfonated naphthalene, sulfonated melamine, vinyl copolymer, and polycarboxylate- based admixtures. With these superplasticizers the slag suspensions had negative zeta potentials, ranging from -3 to -10 mV. For the first time the adsorbed layer thicknesses for superplasticizers on slag using colloidal probe atomi...

  14. Repulsion forces of superplasticizers on ground granulated blast furnace slag in alkaline media, from AFM measurements to rheological properties

    Palacios, M.; Kappl, M.; Stuer, M; Aschauer, U.; Bowen, P.; Butt, H. J.; Pecharromán, Carlos; Puertas, F.

    2012-01-01

    [EN]The electrostatic and steric repulsion induced by different superplasticizers on ground granulated blast furnace slag in alkaline media have been studied. The superplasticizers were sulfonated naphthalene, sulfonated melamine, vinyl copolymer, and polycarboxylate- based admixtures. With these superplasticizers the slag suspensions had negative zeta potentials, ranging from -3 to -10 mV. For the first time the adsorbed layer thicknesses for superplasticizers on slag...

  15. Nonlocal field correlations and dynamical Casimir-Polder forces between one excited- and two ground-state atoms

    The problem of nonlocality in the dynamical three-body Casimir-Polder interaction between an initially excited and two ground-state atoms is considered. It is shown that the nonlocal spatial correlations of the field emitted by the excited atom during the initial part of its spontaneous decay may become manifest in the three-body interaction. The observability of this new phenomenon is discussed

  16. [Environmental investigation of ground water contamination at Wright-Patterson Air Force Base, Ohio]. Volume 3, Sampling and analysis plan (SAP): Phase 1, Task 4, Field Investigation: Draft

    1991-10-01

    In April 1990, Wright-Patterson Air Force Base (WPAFB), initiated an investigation to evaluate a potential Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) removal action to prevent, to the extent practicable, the offsite migration of contaminated ground water from WPAFB. WPAFB retained the services of the Environmental Management Operations (EMO) and its principle subcontractor, International Technology Corporation (IT) to complete Phase 1 of the environmental investigation of ground-water contamination at WPAFB. Phase 1 of the investigation involves the short-term evaluation and potential design for a program to remove ground-water contamination that appears to be migrating across the western boundary of Area C, and across the northern boundary of Area B along Springfield Pike. Primarily, Task 4 of Phase 1 focuses on collection of information at the Area C and Springfield Pike boundaries of WPAFB. This Sampling and Analysis Plan (SAP) has been prepared to assist in completion of the Task 4 field investigation and is comprised of the Quality Assurance Project Plan (QAPP) and the Field Sampling Plan (FSP).

  17. Influence of Coulomb and nuclear forces on the pattern of the double differential cross section d2sigma/d theta dE for deep inelastic reactions

    The tremendous change in the pattern of the Wilczynski curves for deep inelastic reactions with the product Z1Z2 is interpreted within a model including both dissipation and statistical fluctuations. The competition between Coulomb and nuclear forces seems to account for this effect

  18. An experimental study on advancement of damping performance of foundations in soft ground. Pt.1: Forced vibration tests of a foundation block constructed on improved soil medium

    Purpose of this study is to enhance attenuation performance of structures that will be constructed in the soft ground area. We conducted material tests to obtain basic properties of the soil cement column. The forced vibration tests then were carried out to acquire dynamic feature of the reinforced concrete block constructed on improved soil mediums. Additional forced vibration tests for various conditions of trenches dug along the block were conducted to obtain fundamental features of damping effect of the side surfaces of the test block. According to results of the material testing, densities of the soil cement columns were 1.45-1.52 g/cm3 and the unconfined compressive strengths were 2.4-4.2 times as large as the specified design strength (1 MPa). In comparison of resonance curves by experiments and simulation analysis, simulation analysis results estimated by the hybrid approach were in good agreement with experiment ones for both the X and Y-directions. From the results of the forced vibration test focusing on various condition of the trenches dug along the test block, it was indicated that response of tamping by the rammer decreased compared with that of treading. (authors)

  19. Effects of the tensor force on the ground and first $2^{+}$ states of the magic $^{54}$Ca nucleus

    Yüksel, E; Khan, E; Bozkurt, K

    2014-01-01

    The magic nature of the $^{54}$Ca nucleus is investigated in the light of the recent experimental results. We employ both HFB and HF+BCS methods using Skyrme-type SLy5, SLy5+T and T44 interactions. The evolution of the single-particle spectra is studied for the N=34 isotones: $^{60}$Fe, $^{58}$Cr, $^{56}$Ti and $^{54}$Ca. An increase is obtained in the neutron spin-orbit splittings of $p$ and $f$ states due to the effect of the tensor force which also makes $^{54}$Ca a magic nucleus candidate. QRPA calculations on top of HF+BCS are performed to investigate the first $J^{\\pi}$=$2^{+}$ states of the calcium isotopic chain. A good agreement for excitation energies is obtained when we include the tensor force in the mean-field part of the calculations. The first $2^{+}$ states indicate a subshell closure for both $^{52}$Ca and $^{54}$Ca nuclei. We confirm that the tensor part of the interaction is quite essential in explaining the neutron subshell closure in $^{52}$Ca and $^{54}$Ca nuclei.

  20. Modeling Study of the Impact of Heterogeneous Reactions on Dust Surfaces on Aerosol Optical Depth and Direct Radiative Forcing over East Asia in Springtime

    LI Jia-Wei; HAN Zhi-Wei

    2011-01-01

    The spatial distributions and interannual variations of aerosol concentrations, aerosol optical depth (AOD), aerosol direct radiative forcings, and their responses to heterogeneous reactions on dust surfaces over East Asia in March 2006-10 were investigated by utilizing a regional coupled climate-chemistry/aerosol model. Anthropogenic aerosol concentrations (inorganic + carbonaceous) were higher in March 2006 and 2008, whereas soil dust reached its highest levels in March 2006 and 2010, resulting in stronger aerosol radiative forcings in these periods. The domain and five-year (2006-10) monthly mean concentrations of anthropogenic and dust aerosols, AOD, and radiative forcings at the surface (SURF) and at the top of the atmosphere (TOA) in March were 2.4 μg m 3 13.1 lag m^-3, 0.18, -19.0 W m^-2, and -7.4 W m^-2, respectively. Heterogeneous reactions led to an increase of total inorganic aerosol concentration; however, the ambient inorganic aerosol concentration decreased, resulting in a smaller AOD and weaker aerosol radiative forcings. In March 2006 and 2010, the changes in ambient inorganic aerosols, AOD, and aerosol radiative forcings were more evident. In terms of the domain and five-year averages, the total inorganic aerosol concentrations increased by 13.7% (0.17 μg m^-3) due to heterogeneous reactions, but the ambient inorganic aerosol concentrations were reduced by 10.5% (0.13 lag m-3). As a result, the changes in AOD, SURF and TOA radiative forcings were estimated to be -3.9% (-0.007), -1.7% (0.34 W m^-2), and -4.3% (0.34 W m^-2), respectively, in March over East Asia.

  1. A new type of power energy for accelerating chemical reactions: the nature of a microwave-driving force for accelerating chemical reactions.

    Zhou, Jicheng; Xu, Wentao; You, Zhimin; Wang, Zhe; Luo, Yushang; Gao, Lingfei; Yin, Cheng; Peng, Renjie; Lan, Lixin

    2016-01-01

    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. PMID:27118640

  2. A new type of power energy for accelerating chemical reactions: the nature of a microwave-driving force for accelerating chemical reactions

    Zhou, Jicheng; Xu, Wentao; You, Zhimin; Wang, Zhe; Luo, Yushang; Gao, Lingfei; Yin, Cheng; Peng, Renjie; Lan, Lixin

    2016-01-01

    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. PMID:27118640

  3. Atomic force microscopy of photochemistry and the Baeyer-Villiger reaction of 4,4{sup '}-dimethylbenzophenone in the solid state

    Zeng, Q.D.; Wang, C.; Xu, S.D.; Bai, C.L. [Inst. of Chemistry, Chinese Academy of Sciences, Beijing (China); Li, Y.; Yan, X.J. [Inst. of Chemical Metallurgy, Chinese Academy of Sciences, Beijing (China)

    2001-08-01

    Nanostructures are formed by photodimerization of crystalline 4,4{sup '}-dimethylbenzophenone (1) through intermolecular hydrogen abstraction and Baeyer-Villiger reaction of 1 with m-chloroperoxybenzoic acid (MCPBA) (5) in the solid state. Atomic force microscopy (AFM) reveals that the crystal face (001) of 1 during photodimerization exhibits volcanoes, whereas the same face (001) of 1 yields both craters and volcanoes all over the surface from the contact edge of the crystals during the Baeyer-Villiger reaction. All the experimental results are correlated with the bulk crystal structure. Molecular interpretation of the AFM features of 1 is given. (orig.)

  4. Measurement of the 2H(p, n) Breakup Reaction at 170 MeV and the Three-Nucleon Force Effects

    The effects of three nucleon force (3NF) have been actively studied via the nucleon–deuteron (Nd) scattering states. The differential cross sections and the vector analyzing powers Ay of the 2H(p, n) inclusive breakup reaction at 170 MeV were measured for the study of 3NF effects in the intermediate energy region. The polarized proton beam of 170 MeV was injected to the deuterated polyethylene (CD2) target and the energy of scattered neutrons were measured by using TOF method. The data were compared with the Faddeev calculations based on modern nucleon–nucleon (NN) forces with and without the 3NF. Concerning the differential cross sections, we can see large discrepancies between the data and the calculations in the region of scattered neutron energies are low, which is similar to the results of the 2H(p, p) inclusive breakup reaction at 250 MeV. (author)

  5. Reactivity from excited state (4)FeO(+) + CO sampled through reaction of ground state (4)FeCO(+) + N2O.

    Ard, Shaun G; Shuman, Nicholas S; Martinez, Oscar; Brown, Steven A; Sawyer, Jordan C; Viggiano, Albert A

    2016-06-21

    The kinetics of the FeCO(+) + N2O reaction have been studied at thermal energies (300-600 K) using a variable temperature selected ion flow tube apparatus. Rate constants and product branching fractions are reported. The reaction is modestly inefficient, proceeding with a rate constant of 6.2 × 10(-11) cm(3) s(-1) at 300 K, with a small negative temperature dependence, declining to 4.4 × 10(-11) cm(3) s(-1) at 600 K. Both Fe(+) and FeO(+) products are observed, with a constant branching ratio of approximately 40:60 at all temperatures. Calculation of the stationary points along the reaction coordinate shows that only the ground state quartet surface is initially sampled resulting in N2 elimination; a submerged barrier along this portion of the surface dictates the magnitude and temperature dependence of the total rate constant. The product branching fractions are determined by the behavior of the remaining (4)OFeCO(+) fragment, and this behavior is compared to that found in the reaction of FeO(+) + CO, which initially forms (6)OFeCO(+). Thermodynamic and kinetic arguments are used to show that the spin-forbidden surface crossing in this region is efficient, proceeding with an average rate constant of greater than 10(12) s(-1). PMID:27334158

  6. Reactivity from excited state 4FeO+ + CO sampled through reaction of ground state 4FeCO+ + N2O

    Ard, Shaun G.; Shuman, Nicholas S.; Martinez, Oscar; Brown, Steven A.; Sawyer, Jordan C.; Viggiano, Albert A.

    2016-06-01

    The kinetics of the FeCO+ + N2O reaction have been studied at thermal energies (300-600 K) using a variable temperature selected ion flow tube apparatus. Rate constants and product branching fractions are reported. The reaction is modestly inefficient, proceeding with a rate constant of 6.2 × 10-11 cm3 s-1 at 300 K, with a small negative temperature dependence, declining to 4.4 × 10-11 cm3 s-1 at 600 K. Both Fe+ and FeO+ products are observed, with a constant branching ratio of approximately 40:60 at all temperatures. Calculation of the stationary points along the reaction coordinate shows that only the ground state quartet surface is initially sampled resulting in N2 elimination; a submerged barrier along this portion of the surface dictates the magnitude and temperature dependence of the total rate constant. The product branching fractions are determined by the behavior of the remaining 4OFeCO+ fragment, and this behavior is compared to that found in the reaction of FeO+ + CO, which initially forms 6OFeCO+. Thermodynamic and kinetic arguments are used to show that the spin-forbidden surface crossing in this region is efficient, proceeding with an average rate constant of greater than 1012 s-1.

  7. Ground effects on USB configurations. [Upper Surface Blowing

    Lan, C. E.

    1979-01-01

    Recent investigations of ground effects on aerodynamic characteristics have been stimulated by the interest in powered-lift STOL airplanes. The ground effects on upper-surface-blowing (USB) configurations may involve change in both the circulation forces and the jet reaction forces. In this note, a theoretical method is proposed for predicting these effects. It is shown that the predicted results agree well with available experimental data. In particular, the wing-alone method is shown to be incapable of predicting the ground effects of USB configurations.

  8. Ground-state correlations in 12C and the mechanism of the (e,e'p) reaction

    In this thesis the results of an investigation into two aspects of the mechanism of the quasi-elastic (e,e'p) reaction: the interaction between the incident electron and the bound proton and the residual nucleus (final-state interaction (FSI)), are presented and used in the extraction of nuclear-structure information from (e,e'p) measurements on 12C. The experiments were carried out at NIKHEF-K with a high-resolution spectrometer. Two kinds of experiments have been performed on 12C. The first was aimed at obtaining accurate momentum distributions for various final states in 11B. Some special measurements were carried out in order to vary the parameters influencing the FSI. The role of coupled-channels effects in the 12C(e,e'p)11Be reaction is discussed. It is discussed whether some of the weak transitions observed in this reaction, can be associated with knockout from normally unoccupied shell-model orbitals. The second experiment on 12C was devoted to the e-p coupling. These measurements were supplemented with data taken on 6Li. The latter measurement allowed for measuring simultaneously knockout from the relatively dense 4He core and the relatively dilute deuteron. In this way the density dependence of the e-p coupling in the nucleus could be studied. The results of these experiments have been compared to various models that take into account the effect of the nuclear medium upon the e-p coupling. The possible role of charge-exchange and meson-exchange currents in the interpretation of these experiments is also considered. A brief survey of the formalism of the quasi-elastic (e,e'p) reaction is also presented. (author). 196 refs.; 53 figs.; 21 tabs

  9. Procedures for addressing uncertainty and variability in exposure to characterize potential health risk from trichloroethylene contaminated ground water at Beale Air Force Base in California; TOPICAL

    Conservative deterministic, screening-level calculations of exposure and risk commonly are used in quantitative assessments of potential human-health consequences from contaminants in environmental media. However, these calculations generally are based on multiple upper-bound point estimates of input parameters, particularly for exposure attributes, and can therefore produce results for decision makers that actually overstate the need for costly remediation. Alternatively, a more informative and quantitative characterization of health risk can be obtained by quantifying uncertainty and variability in exposure. This process is illustrated in this report for a hypothetical population at a specific site at Beale Air Force Base in California, where there is trichloroethylene (TCE) contaminated ground water and a potential for future residential use. When uncertainty and variability in exposure were addressed jointly for this case, the 95th-percentile upper-bound value of individual excess lifetime cancer risk was a factor approaching 10 lower than the most conservative deterministic estimate. Additionally, the probability of more than zero additional cases of cancer can be estimated, and in this case it is less than 0.5 for a hypothetical future residential population of up to 26,900 individuals present for any 7.6-y interval of a 70-y time period. Clearly, the results from application of this probabilistic approach can provide reasonable and equitable risk-acceptability criteria for a contaminated site

  10. Procedures for addressing uncertainty and variability in exposure to characterize potential health risk from trichloroethylene contaminated ground water at Beale Air Force Base in California

    Daniels, J I; Bogen, K T; Hall, L C

    1999-10-05

    Conservative deterministic, screening-level calculations of exposure and risk commonly are used in quantitative assessments of potential human-health consequences from contaminants in environmental media. However, these calculations generally are based on multiple upper-bound point estimates of input parameters, particularly for exposure attributes, and can therefore produce results for decision makers that actually overstate the need for costly remediation. Alternatively, a more informative and quantitative characterization of health risk can be obtained by quantifying uncertainty and variability in exposure. This process is illustrated in this report for a hypothetical population at a specific site at Beale Air Force Base in California, where there is trichloroethylene (TCE) contaminated ground water and a potential for future residential use. When uncertainty and variability in exposure were addressed jointly for this case, the 95th-percentile upper-bound value of individual excess lifetime cancer risk was a factor approaching 10 lower than the most conservative deterministic estimate. Additionally, the probability of more than zero additional cases of cancer can be estimated, and in this case it is less than 0.5 for a hypothetical future residential population of up to 26,900 individuals present for any 7.6-y interval of a 70-y time period. Clearly, the results from application of this probabilistic approach can provide reasonable and equitable risk-acceptability criteria for a contaminated site.

  11. How low-energy weak reactions can constrain three-nucleon forces and the neutron-neutron scattering length

    Gardestig, A.; Phillips, D.R.

    2006-01-01

    We show that chiral symmetry and gauge invariance enforce relations between the short-distance physics that occurs in a number of electroweak and pionic reactions on light nuclei. Within chiral perturbation theory this is manifested via the appearance of the same axial isovector two-body contact term in pi- d -> n n gamma, p-wave pion production in NN collisions, tritium beta decay, pp fusion, nu d scattering, and the hep reaction. Using a Gamow-Teller matrix element obtained from calculation...

  12. Self-medication of anaphylactic reactions due to Hymenoptera stings-an EAACI Task Force Consensus Statement.

    Bilò, M B; Cichocka-Jarosz, E; Pumphrey, R; Oude-Elberink, J N; Lange, J; Jakob, T; Bonadonna, P; Fernandez, J; Kosnik, M; Helbling, A; Mosbech, H; Gawlik, R; Niedoszytko, M; Patella, V; Pravettoni, V; Rodrigues-Alves, R; Sturm, G J; Rueff, F

    2016-07-01

    An anaphylactic reaction due to a Hymenoptera sting is a clinical emergency, and patients, their caregivers as well as all healthcare professionals should be familiar with its recognition and acute management. This consensus report has been prepared by a European expert panel of the EAACI Interest Group of Insect Venom Hypersensitivity. It is targeted at allergists, clinical immunologists, internal medicine specialists, pediatricians, general practitioners, emergency department doctors, and any other healthcare professional involved. The aim was to report the scientific evidence on self-medication of anaphylactic reactions due to Hymenoptera stings, to inform healthcare staff about appropriate patient self-management of sting reactions, to propose indications for the prescription of an adrenaline auto-injector (AAI), and to discuss other forms of medication. First-line treatment for Hymenoptera sting anaphylaxis is intramuscular adrenaline. Prescription of AAIs is mandatory in the case of venom-allergic patients who suffer from mast cell diseases or with an elevated baseline serum tryptase level and in untreated patients with a history of a systemic reaction involving at least two different organ systems. AAI prescription should also be considered in other specific situations before, during, and after stopping venom immunotherapy. PMID:27060567

  13. Study of the Three-Nucleon Force Effects in the 2H(p, n) Breakup Reaction at 170 MeV

    For the study of three nucleon force (3NF) effects in the intermediate energy region, the differential cross sections and the vector analyzing power Ay were measured for the 2H(p, n) inclusive breakup reaction at 170 MeV. The polarized proton beam of 170 MeV was injected to the deuterated polyethylene (CD2) target and the energy of scattered neutrons were deduce by TOF method. The data was compared with the results of the Faddeev calculations with and without 3NFs. Concerning about the differential cross sections, we can see large discrepancies between the data and the calculations in the region where the energies of scattered neutrons are low, which are similar to the results of the 2H(p, p) inclusive breakup reaction at 250 MeV. (author)

  14. Odd oxygen formation in the laser irradiation of O2 at 248 nm - Evidence for reactions of O2 in the Herzberg states with ground state O2

    Shi, Jichun; Barker, John R.

    1992-01-01

    Two O3 formation processes (initiation and autocatalytic) are studied in pure O2 and in O2+N2 and O2+Ar mixtures at pressures between 200 and 1600 torr and at temperatures between 298 and 370 K. Evidence is presented that the initiation process produces O3 through chemical reactions between ground state O2 and excited O2 in the Herzberg states, which are produced by the photoabsorption of O2 at 248 nm. For the autocatalytic process, the results are consistent with the proposal that the O3 formation is accelerated by photodissociating vibrationally excited O2(nu), produced in the photolysis of O3 following its initial formation. It is argued that the O2 Herzberg states and O2(nu) may play important roles in the odd oxygen chemistry in the middle atmosphere. It is estimated that the O2(A3Sigma-u(+))+O2 reaction may yield up to about 6 percent of the total odd oxygen production rate near 50 km.

  15. How low-energy weak reactions can constrain three-nucleon forces and the neutron-neutron scattering length

    Gardestig, A

    2006-01-01

    We show that chiral symmetry and gauge invariance enforce relations between the short-distance physics that occurs in a number of electroweak and pionic reactions on light nuclei. Within chiral perturbation theory this is manifested via the appearance of the same axial isovector two-body contact term in pi- d -> n n gamma, p-wave pion production in NN collisions, tritium beta decay, pp fusion, nu d scattering, and the hep reaction. Using a Gamow-Teller matrix element obtained from calculations of pp fusion as input we compute the neutron spectrum obtained in pi- d -> n n gamma. With the short-distance physics in this process controlled from p p -> d e+ nu_e the theoretical uncertainty in the nn scattering length extracted from pi- d -> n n gamma is reduced by a factor larger than three, to <~0.05 fm.

  16. How low-energy weak reactions can constrain three-nucleon forces and the neutron-neutron scattering length.

    Gårdestig, A; Phillips, D R

    2006-06-16

    We show that chiral symmetry and gauge invariance enforce relations between the short-distance physics that occurs in a number of electroweak and pionic reactions on light nuclei. Within chiral perturbation theory, this is manifested via the appearance of the same axial isovector two-body contact term in pi(-)d --> nngamma, p-wave pion production in NN collisions, tritium beta decay, pp fusion, nud scattering, and the hep reaction. Using a Gamow-Teller matrix element obtained from calculations of pp fusion as input, we compute the neutron spectrum obtained in pi(-)d --> nngamma. With the short-distance physics in this process controlled from pp --> de(=)nu(e), the theoretical uncertainty in the nn scattering length extracted from pi(-)d --> nngamma is reduced by a factor larger than 3, to approximately < or = 0.05 fm. PMID:16803373

  17. Mass Transfer and Reaction Kinetics in the Carbonization of Magnesium Oxide from Light Calcined Magnesia with Mechanical Force Enhancement

    张焕军; 朱国才

    2004-01-01

    The carbonization of magnesium oxide particles by CO2 was investigated using a stirring mill reactor.The effects of the system temperature, stirring rotation speed, influx rate of CO2 and initial diameter of the magnesium oxide particles on the carbonization process were determined. The results show that the system temperature and the stirring rotation speed are the most significant influencing factors on the carbonization rate. The determination of critical decomposition temperature (CDT) gives the maximum carbonization rate with other conditions fixed. A theoretical model involving mass transfer and reaction kinetics was presented for the carbonization process.The apparent activation energy was calculated to be 32.8kJ·mo1-1. The carbonization process is co-controlled by diffusive mass transfer and chemical reaction. The model fits well with the experimental results.

  18. The brute-force polarization of 23Na and the 23Na(n,γ)24Na reaction

    A Na target has been polarized by brute force to 22% and the γ radiation produced by polarized thermal neutron capture has been investigated. The 2+ channel spin contribution has been determined model independently and unambiguously for 22 primary transitions. The average 2+ channel contribution is 5.8(5)%. Spins of final levels are in agreement with previous assignments. For three levels spin restrictions have been made. The energies of positive parity levels are in agreement with a shell model calculation in the complete sd shell. (Auth.)

  19. Measurement of the reaction 3He(γ,pp)n and its relation to three-body forces

    The three-body photodisintegration of 3He has been measured at photon energies ranging from 90 to 250 MeV, in kinematic regions where three-body forces effects are expected to be maximized, and two-body mechanisms suppressed. The differential cross sections as a function of neutron momentum demonstrate that calculations using only one-body and two-body photoabsorption mechanisms cannot describe the data and that a two-pion-exchange, three-body absorption mechanism is needed to adequately describe the data

  20. Two-phase flow characteristics of hot water discharged from a thin nozzle. 1st Report. Boiling two-phase flow rate in a nozzle and reaction force by two-phase jet

    An experimental and analytical study on the mass flux and reaction force of water single-phase and steam-water two-phase jets discharged from a thin nozzle was carried out. The mass flux of water jet is well predicted using the Bernoulli's equation with the contraction coefficient, but the recovery of contraction at the nozzle exit should be considered to evaluate the reaction force. The L/D of the nozzle affects the mass flux and reaction force of the two-phase jet, i.e., the mass flux decreases and the reaction force increases with the L/D. The behavior of high-temperature water jet is similar to that of the water jet if the L/D is smaller or nozzle inlet pressure is higher. The behaviors of the mass flux and the reaction force show hysteresis depending on the decrease or increase of nozzle inlet pressure. The mass flux and reaction force can be well predicted by the critical flow analysis based on a separated flow model with the non-equilibrium parameter. (author)

  1. Two-phase flow characteristics of hot water discharged from a thin nozzle. 1st Report. Boiling two-phase flow rate in a nozzle and reaction force by two-phase jet

    Hamada, Hirotsugu [Japan Nuclear Cycle Development Inst., Oarai, Ibaraki (Japan). Oarai Engineering Center; Takahashi, Minoru; Inoue, Akira; Aritomi, Masanori [Tokyo Inst. of Tech. (Japan)

    2003-01-01

    An experimental and analytical study on the mass flux and reaction force of water single-phase and steam-water two-phase jets discharged from a thin nozzle was carried out. The mass flux of water jet is well predicted using the Bernoulli's equation with the contraction coefficient, but the recovery of contraction at the nozzle exit should be considered to evaluate the reaction force. The L/D of the nozzle affects the mass flux and reaction force of the two-phase jet, i.e., the mass flux decreases and the reaction force increases with the L/D. The behavior of high-temperature water jet is similar to that of the water jet if the L/D is smaller or nozzle inlet pressure is higher. The behaviors of the mass flux and the reaction force show hysteresis depending on the decrease or increase of nozzle inlet pressure. The mass flux and reaction force can be well predicted by the critical flow analysis based on a separated flow model with the non-equilibrium parameter. (author)

  2. Study on HCl Driving Force for the Reaction of NaCl-Maleic Acid Mixing Single Droplet Using Micro-FTIR Spectroscopy

    He, Xiang; Zhang, Yunhong

    2016-04-01

    Chemical aging is the one of the most important physicochemical process in atmospheric aerosols. Mixing of sea salt and water-soluble organic components has profound effects on the volatile characteristic and evolving chemical composition of the anthropogenic origin aerosols, which are poorly understood. In this study, the chemical reaction behavior of the mixture of NaCl and maleic acid (H2MA) micron-level single droplet was investigated using a gas-flow system combined with microscopic Fourier transform infrared (micro-FTIR) spectrometer over the range of relative humidity (63˜95% RH) for the first time. The results showed that the mixture of NaCl and H2MA single droplet could react to form monosodium maleate salt (NaHMA) at the constant RH from the characterization of the FTIR. The reaction is a result of an acid displacement reaction R1, which is driven by high volatility of the HCl product. NaCl(aq)+H2MA(aq)=NaHMA(aq)+HCl(aq,g) (R1) According to the change tendency of the absorbance values of 1579 cm‑1 COO‑ stretching band of the NaHMA dependent upon reaction times at different RHs, the growth range of the trend which could lead to the faster reaction rate was obvious at lower RH. The water content of the droplet was also more likely to reduce rapidly with the loss of the RH from the absorbance changes of 3400 cm‑1H2O stretching band dependent upon reaction times. These may be due to irreversible evaporation of HCl gas which is the main driving force for this type of reaction and the NaHMA is a less hygroscopic component compared to H2MA. And the HCl gas is more likely to evaporate faster from the single droplet and promote the reaction rate and the consumption of water content at lower RH. These results could help in understanding the chemical conversion processes of water-soluble dicarboxylic acids to dicarboxylate salts, as well as the consumption of Cl in sea salt aerosols by organic acids in the atmosphere.

  3. Testing the cosmic censorship conjecture with point particles: The effect of radiation reaction and the self-force

    A classical thought-experiment to destroy black holes was envisaged by Wald in 1974: it consists of throwing particles with large angular momentum into an extremal black hole, checking whether their capture can overspin the black hole past the extremal limit and create a naked singularity. Wald showed that in the test-particle limit, particles that would be otherwise capable of producing naked singularities are simply scattered. Recently, Jacobson and Sotiriou showed that if one considers instead a black hole that is almost, but not exactly extremal, then in the absence of backreaction effects particle capture could indeed overspin the spacetime above the Kerr limit. Here we analyze backreaction effects and show that for some of the trajectories giving rise to naked singularities, radiative effects can be neglected. However, for these orbits the conservative self-force is important, and seems to have the right sign to prevent the formation of naked singularities.

  4. The chemical hardness of molecules and the band gap of solids within charge equilibration formalisms. Toward force field-based simulations of redox reactions

    Müser, M. H.

    2012-04-01

    This work finds that different charge equilibration methods lead to qualitatively different responses of molecules and solids to an excess charge. The investigated approaches are the regular charge equilibration (QE), the atom-atom-charge transfer (AACT), and the split-charge equilibration (SQE) method. In QE, the hardness of molecules and the band gap of solids approaches zero at large particle numbers, affirming the claim that QE induces metallic behavior. AACT suffers from producing negative values of the hardness; moreover valence and conduction bands of solids cross. In contrast to these methods, SQE can reproduce the generic behavior of dielectric molecules or solids. Moreover, first quantitative results for the NaCl molecule are promising. The results derived in this work may have beneficial implications for the modeling of redox reactions. They reveal that by introducing formal oxidation states into force field-based simulations it will become possible to simulate redox reactions including non-equilibrium contact electrification, voltage-driven charging of galvanic cells, and the formation of zwitterionic molecules.

  5. Development of a Subject-Specific Foot-Ground Contact Model for Walking.

    Jackson, Jennifer N; Hass, Chris J; Fregly, Benjamin J

    2016-09-01

    Computational walking simulations could facilitate the development of improved treatments for clinical conditions affecting walking ability. Since an effective treatment is likely to change a patient's foot-ground contact pattern and timing, such simulations should ideally utilize deformable foot-ground contact models tailored to the patient's foot anatomy and footwear. However, no study has reported a deformable modeling approach that can reproduce all six ground reaction quantities (expressed as three reaction force components, two center of pressure (CoP) coordinates, and a free reaction moment) for an individual subject during walking. This study proposes such an approach for use in predictive optimizations of walking. To minimize complexity, we modeled each foot as two rigid segments-a hindfoot (HF) segment and a forefoot (FF) segment-connected by a pin joint representing the toes flexion-extension axis. Ground reaction forces (GRFs) and moments acting on each segment were generated by a grid of linear springs with nonlinear damping and Coulomb friction spread across the bottom of each segment. The stiffness and damping of each spring and common friction parameter values for all springs were calibrated for both feet simultaneously via a novel three-stage optimization process that used motion capture and ground reaction data collected from a single walking trial. The sequential three-stage process involved matching (1) the vertical force component, (2) all three force components, and finally (3) all six ground reaction quantities. The calibrated model was tested using four additional walking trials excluded from calibration. With only small changes in input kinematics, the calibrated model reproduced all six ground reaction quantities closely (root mean square (RMS) errors less than 13 N for all three forces, 25 mm for anterior-posterior (AP) CoP, 8 mm for medial-lateral (ML) CoP, and 2 N·m for the free moment) for both feet in all walking trials. The

  6. Impulse-forces during walking are not increased in patients with knee osteoarthritis

    Henriksen, Marius; Simonsen, Erik B; Graven-Nielsen, Thomas;

    2006-01-01

    BACKGROUND: Impulsive forces in the knee joint have been suspected to be a co-factor in the development and progression of knee osteoarthritis. We thus evaluated the impulsive sagittal ground reaction forces (iGRF), shock waves and lower extremity joint kinematics at heel strike during walking in...... range. Our findings make us question the hypothesis that impulse-forces generated at heel strike during walking contribute to progression of OA....

  7. Analysis of Aerosol Radiative Forcing over Beijing under Different Air Quality Conditions Using Ground-Based Sun-Photometers between 2013 and 2015

    Wei Chen; Lei Yan; Nan Ding; Mengdie Xie; Ming Lu; Fan Zhang; Yongxu Duan; Shuo Zong

    2016-01-01

    Aerosol particles can strongly affect both air quality and the radiation budget of the atmosphere. Above Beijing, the capital city of China, large amounts of aerosols within the atmospheric column have caused the deterioration of local air quality and have influenced radiative forcings at both the top and the bottom of the atmosphere (BOA and TOA). Observations of aerosol radiative forcing and its efficiency have been made using two sun-photometers in urban Beijing between 2013 and 2015, and ...

  8. The CMS Experiment: on and under Ground Motions of Structures Due to the Magnetic Field Forces as Observed by the Link Alignment System

    Alberdi, J.; Arce, J.; Barcala, J. M.; Calvo, E.; Ferrando, A.; Josa, M. I.; Molinero, A.; Navarrete, J.; Oller, J. C.; Yuste, C.; Brochero, J.; Calderon, A.; Fernandez, M. G.; Gomez, G.; Gonzalez-Sanchez, F. J.; Martinez-Ribero, C.; Matorras, F.; Rodrigo, T.; Rui-Arbol, P.; Scodellaro, L.; Sobron, M.; Vila, I.; Virto, A. L.; Fernandez, J.

    2010-05-01

    This document describes results obtained from the Link Alignment System data recorded during the CMS Magnet Test (at SX5 on ground Hall) and the CRAFT08 and 09 periods data taking in the point P5 (UX5), 100 m underground. A brief description of the system is followed by the discussion of the detected relative displacements (from micrometres to centimetres) between detector elements and rotation of detector structures (from microradiants to milliradiants). Observed motions are studied as functions of the magnetic fi eld intensity. Comparisons between recorded data on and under ground are made. (Author) 23 refs.

  9. The CMS Experiment: on and under Ground Motions of Structures Due to the Magnetic Field Forces as Observed by the Link Alignment System

    This document describes results obtained from the Link Alignment System data recorded during the CMS Magnet Test (at SX5 on ground Hall) and the CRAFT08 and 09 periods data taking in the point P5 (UX5), 100 m underground. A brief description of the system is followed by the discussion of the detected relative displacements (from micrometres to centimetres) between detector elements and rotation of detector structures (from microradiants to milliradiants). Observed motions are studied as functions of the magnetic fi eld intensity. Comparisons between recorded data on and under ground are made. (Author) 23 refs.

  10. Large atmospheric shortwave radiative forcing by Mediterranean aerosols derived from simultaneous ground-based and spaceborne observations and dependence on the aerosol type and single scattering albedo

    di Biagio, Claudia; di Sarra, Alcide; Meloni, Daniela

    2010-05-01

    Aerosol optical properties and shortwave irradiance measurements at the island of Lampedusa (central Mediterranean) during 2004-2007 are combined with Clouds and the Earth's Radiant Energy System observations of the outgoing shortwave flux at the top of the atmosphere (TOA). The measurements are used to estimate the surface (FES), the top of the atmosphere (FETOA), and the atmospheric (FEATM) shortwave aerosol forcing efficiencies for solar zenith angle (θ) between 15° and 55° for desert dust (DD), urban/industrial-biomass burning aerosols (UI-BB), and mixed aerosols (MA). The forcing efficiency at the different atmospheric levels is derived by applying the direct method, that is, as the derivative of the shortwave net flux versus the aerosol optical depth at fixed θ. The diurnal average forcing efficiency at the surface/TOA at the equinox is (-68.9 ± 4.0)/(-45.5 ± 5.4) W m-2 for DD, (-59.0 ± 4.3)/(-19.2 ± 3.3) W m-2 for UI-BB, and (-94.9 ± 5.1)/(-36.2 ± 1.7) W m-2 for MA. The diurnal average atmospheric radiative forcing at the equinox is (+7.3 ± 2.5) W m-2 for DD, (+8.4 ± 1.9) W m-2 for UI-BB, and (+8.2 ± 1.9) W m-2 for MA, suggesting that the mean atmospheric forcing is almost independent of the aerosol type. The largest values of the atmospheric forcing may reach +35 W m-2 for DD, +23 W m-2 for UI-BB, and +34 W m-2 for MA. FETOA is calculated for MA and 25° ≤ θ ≤ 35° for three classes of single scattering albedo (0.7 ≤ ω < 0.8, 0.8 ≤ ω < 0.9, and 0.9 ≤ ω ≤ 1) at 415.6 and 868.7 nm: FETOA increases, in absolute value, for increasing ω. A 0.1 increment in ω determines an increase in FETOA by 10-20 W m-2.

  11. Dynamical response of the Galileo Galilei on the ground rotor to test the equivalence principle: Theory, simulation, and experiment. II. The rejection of common mode forces

    'Galileo Galilei on the ground' (GGG) is a fast rotating differential accelerometer designed to test the equivalence principle (EP). Its sensitivity to differential effects, such as the effect of an EP violation, depends crucially on the capability of the accelerometer to reject all effects acting in common mode. By applying the theoretical and simulation methods reported in Part I of this work, and tested therein against experimental data, we predict the occurrence of an enhanced common mode rejection of the GGG accelerometer. We demonstrate that the best rejection of common mode disturbances can be tuned in a controlled way by varying the spin frequency of the GGG rotor

  12. Study on the 8He ground state via 8He(p, d)7He and 8He(p, t)6He reaction at 82.3 MeV/nucleon

    The differential cross sections for reactions 8He(p, d)7Heg.s and 8He(p, t)6He2+ were measured by the coincidence of d + 6 He and t + 4He in a wide angular range from 15 to 130 degree in the center-of-mass system. The cross sections of the 8He(p, t)6Heg.s reaction were extremely lower than that of 8He(p, t)6He2+ reaction, and was not obtained from the present data. The experimental results were compared to the preliminary theoretical calculations in the frame of adiabatic distorted-wave approximation with the code Fresco. The results show that the configuration of (1p3/2)2(1p1/2)2 may have some probability in the ground state wave function of 8He. The cluster structure of 8He = 5H + 3H could not be neglected.

  13. Three-body forces

    Three-body forces are defined and their properties discussed. Evidence for such forces in the trinucleon bound states and scattering reactions is reviewed. The binding energy defects of the trinucleon bound states, the 3He charge density, the Phillips line for doublet n-d scattering lengths, and three-nucleon breakup reactions are discussed, together with the possible influence of three-body forces on these observables

  14. Light induced electron transfer reactions of metal complexes

    Properties of the excited states of tris(2,2'-bipyridine) and tris(1,10-phenanthroline) complexes of chromium(III), iron(II), ruthenium(II), osmium(II), rhodium(III), and iridium(III) are described. The electron transfer reactions of the ground and excited states are discussed and interpreted in terms of the driving force for the reaction and the distortions of the excited states relative to the corresponding ground states. General considerations relevant to the conversion of light into chemical energy are presented and progress in the use of polypyridine complexes to effect the light decomposition of water into hydrogen and oxygen is reviewed

  15. Quantum, Statistical, and Quasiclassical Trajectory Studies For the Ne + HeH(+) → NeH(+) + He Reaction on the Ground Electronic State.

    Koner, Debasish; Barrios, Lizandra; González-Lezana, Tomás; Panda, Aditya N

    2015-12-17

    Real wave packet, statistical quantum, and quasiclassical trajectory methods were employed to study the dynamics of Ne + HeH(+)(v0,j0) → He + NeH(+) reaction on an ab initio potential energy surface [J. Phys. Chem. A 2013, 117, 13070-13078]. Quantum and statistical quantum calculations were performed within the centrifugal sudden (CS) approximation as well as including the Coriolis coupling (CC). Dense oscillatory structures of the quantum reaction probabilities and fair agreement between quantum and statistical cross sections suggest a complex forming mechanism for the reaction. No significant differences between cross sections obtained within the CS and CC approaches are observed. Quasiclassical trajectory results give an excellent average description of the quantum CC results. At low collision energies, there is a substantial decrease in reactivity for the reaction upon rovibrational excitation. Initial state selected rate constants for the title reaction are calculated between 20 and 1000 K, and the calculated value at 300 K agrees quite well with the available experimental result. Reaction cross sections and rate constants are also compared with those calculated via the Langevin capture model for exothermic reactions. PMID:26172109

  16. Equilibrium constants in aqueous lanthanide and actinide chemistry from time-resolved fluorescence spectroscopy: The role of ground and excited state reactions

    Equilibrium constants for aqueous reactions between lanthanide or actinide ions and (in-) organic ligands contain important information for various radiochemical problems, such as nuclear reprocessing or the migration of radioelements in the geosphere. We study the conditions required to determine equilibrium constants by time-resolved fluorescence spectroscopy measurements. Based on a simulation study it is shown that the possibility to determine equilibrium constants depends upon the reaction rates in the photoexcited states of the lanthanide or actinide ions. (orig.)

  17. Ground-state and isomeric-state cross sections for the {sup 138}Ce(n,2n){sup 137}Ce reaction from its threshold to 20 MeV

    Luo, Junhua [Hexi Univ., Zhangye (China). Inst. of Theoretical Physics; Hexi Univ., Zhangye (China). School of Physics and Electromechanical Engineering; An, Li; Jiang, Li [Chinese Academy of Engineering Physics, Mianyang (China). Inst. of Nuclear Physics and Chemistry

    2015-07-01

    The cross sections of the {sup 138}Ce(n,2n){sup 137}Ce reactions and their isomeric cross section ratios σ{sub m}/σ{sub g} were measured at three neutron energies between 13.5 and 14.8 MeV using the activation technique. CeO{sub 2} samples and Nb monitor foils were activated together to determine the reaction cross section and the incident neutron flux. The monoenergetic neutron beams were formed via the {sup 3}H(d,n){sup 4}He reaction. The activities induced in the reaction products were measured using high-resolution γ-ray spectroscopy. The pure cross section of the ground-state was derived from the absolute cross section of the metastable state and the residual nuclear decay analysis. The cross sections were also estimated using the nuclear model code, TALYS-1.6 with different level density options at neutron energies varying from the reaction threshold to 20 MeV. Results are discussed and compared with the corresponding literature data.

  18. Communication: Direct comparison between theory and experiment for correlated angular and product-state distributions of the ground-state and stretching-excited O(3P) + CH4 reactions

    Motivated by a recent experiment [H. Pan and K. Liu, J. Chem. Phys. 140, 191101 (2014)], we report a quasiclassical trajectory study of the O(3P) + CH4(vk = 0, 1) → OH + CH3 [k = 1 and 3] reactions on an ab initio potential energy surface. The computed angular distributions and cross sections correlated to the OH(v = 0, 1) + CH3(v = 0) coincident product states can be directly compared to experiment for O + CH4(v3 = 0, 1). Both theory and experiment show that the ground-state reaction is backward scattered, whereas the angular distributions shift toward sideways and forward directions upon antisymmetric stretching (v3) excitation of the reactant. Theory predicts similar behavior for the O + CH4(v1 = 1) reaction. The simulations show that stretching excitation enhances the reaction up to about 15 kcal/mol collision energy, whereas the O + CH4(vk = 1) reactions produce smaller cross sections for OH(v = 1) + CH3(v = 0) than those of O + CH4(v = 0) → OH(v = 0) + CH3(v = 0). The former finding agrees with experiment and the latter awaits for confirmation. The computed cold OH rotational distributions of O + CH4(v = 0) are in good agreement with experiment

  19. Investigating the relationship between pressure force and acoustic waveform in footstep sounds

    Grani, Francesco; Serafin, Stefania; Götzen, Amalia De;

    2013-01-01

    In this paper we present an inquiry into of the relationships between audio waveforms and ground reaction force in recorded footstep sounds. In an anechoic room, we recorded several footstep sounds produced while walking on creaking wood and gravel. The recordings were performed by using a pair o...

  20. Ab initio study of {sup 2}H(d,{gamma}){sup 4}He, {sup 2}H(d,p){sup 3}H, and {sup 2}H(d,n){sup 4}He reactions and the tensor force

    Arai, K.; Aoyama, S.; Suzuki, Y.; Descouvemont, P.; Baye, D. [Division of General Education, Nagaoka National College of Technology, 888 Nishikatakai, Nagaoka, Niigata, 940-8532 (Japan); Center for Academic Information Service, Niigata University, Niigata 950-2181 (Japan); Department of Physics, Niigata University, Niigata 950-2181, Japan and RIKEN Nishina Center, Wako 351-0198 (Japan); Physique Nucleaire Theorique et Physique Mathematique, C.P.229, Universite Libre de Bruxelles, B 1050 Brussels (Belgium); Physique Quantique, CP165/82, Universite Libre de Bruxelles, B-1050 Brussels (Belgium)

    2012-11-12

    The {sup 2}H(d,p){sup 3}H, {sup 2}H(d,n){sup 3}He, and {sup 2}H(d,{gamma}){sup 4}He reactions at low energies are studied with realistic nucleon-nucleon interactions in an ab initio approach. The obtained astrophysical S-factors are all in very good agreement with experiment. The most important channels for both transfer and radiative capture are all found to dominate thanks to the tensor force.

  1. Large-eddy simulation of pollutant dispersion from a ground-level area source over urban street canyons with irreversible chemical reactions

    Du, T. Z.; Liu, C.-H.; Zhao, Y. B.

    2014-01-01

    In this study, the dispersion of chemically reactive pollutants is calculated by large-eddy simulation (LES) in a neutrally stratified urban canopy layer (UCL) over urban areas. As a pilot attempt, idealized street canyons of unity building-height-to-street-width (aspect) ratio are used. Nitric oxide (NO) is emitted from the ground surface of the first street canyon into the domain doped with ozone (O3). In the absence of ultraviolet radiation, this irreversible chemistry pr...

  2. ESR in zero field of the photoinduced triplet state in isolated reaction centers of rhodopseudomonas sphaeroides R-26 detected by the singlet ground-state absorbance

    Den Blanken, H. J.; Van Der Zwet, G. P.; Hoff, A. J.

    1982-01-01

    We have measured zero-field resonance transitions of the triplet state of the primary donor monitoring the transmittance at 890 nm at 1.2 K in isolated reaction centers of Rhodopseudomonas sphaeroides R-26. The transitions correspond to a decrease in transmittance, confirming the energy transfer model for the transitions detected via the antenna fluorescence in whole cells.

  3. Applying the cost of generating force hypothesis to uphill running

    Wouter Hoogkamer; Paolo Taboga; Rodger Kram

    2014-01-01

    Historically, several different approaches have been applied to explain the metabolic cost of uphill human running. Most of these approaches result in unrealistically high values for the efficiency of performing vertical work during running uphill, or are only valid for running up steep inclines. The purpose of this study was to reexamine the metabolic cost of uphill running, based upon our understanding of level running energetics and ground reaction forces during uphill running. In contrast...

  4. Cross sections of ground and isomeric states for (n,p) reaction on Sm-154 between 13.57 and 14.83MeV neutrons.

    Reyhancan, Iskender Atilla

    2016-07-01

    In this study, the activation cross sections were measured for the (154)Sm(n,p)(154g)Pm, and (154)Sm(n,p)(154m)Pm reactions at several neutron energies between 13.57 and 14.83MeV, which were produced by the neutron generator (SAMES T-400) through the (3)H((2)H,n)(4)He reaction. The production of short-lived activity and the spectra accumulation were performed by the cyclic activation technique. Induced gamma-ray activities were measured using a high resolution gamma ray spectrometer equipped with a high-purity Germanium (HPGe) detector. In the cross section measurements, corrections were made regarding the effects of gamma-ray attenuation, dead-time, fluctuation of neutron flux, and low energy neutrons. The measured cross sections were compared with data reported in literature as well as model calculations using the code TALYS 1.6. PMID:27149398

  5. Testing nuclear forces by polarization transfer coefficients in d(\\vec p, \\vec p)d and d(\\vec p,\\vec d)p reactions at E^{lab}_p = 22.7 MeV

    Witala, H; Glöckle, W; Golak, J; Kamada, H; Kievsky, A; Nogga, A; Skibinski, R; Viviani, M

    2006-01-01

    The proton to proton polarization transfer coefficients K_x^{x'}, K_y^{y'}, K_z^{x'} and the proton to deuteron polarization transfer coefficients K_x^{x'}, K_y^{y'}, K_z^{x'}, K_x^{y'z'}, K_y^{z'z'}, K_z^{y'z'}, K_y^{x'z'} and K_y^{x'x'-y'y'} have been measured in d(\\vec p, \\vec p)d and d(\\vec p, \\vec d)p reactions at E^{lab}_p = 22.7 MeV, respectively. The data have been compared to predictions of modern nuclear forces obtained by solving the three-nucleon Faddeev equations in momentum space. Realistic (semi) phenomenological nucleon-nucleon potentials combined with model three-nucleon forces and modern chiral nuclear forces have been used. The AV18, CD Bonn, Nijm I and II nucleon-nucleon interactions have been applied alone or combined with the Tucson-Melbourne 99 three-nucleon force, adjusted separately for each potential to reproduce the triton binding energy. For the AV18 potential also the Urbana IX three-nucleon force have been used. In addition chiral NN potentials in the next-to-leading-order and ch...

  6. Ground subgroups

    Rozikov, U. A.

    2009-01-01

    In this article we give a concept of ground subgroup for finite and countable groups. By our definition such a subgroup of a group depends on a given subset of the group and on a given partition of the subset. For finite and free groups we describe some sets of ground subgroups. We apply the ground subgroups to describe ground states of a model of statistical mechanics.

  7. Variability of a "force signature" during windmill softball pitching and relationship between discrete force variables and pitch velocity.

    Nimphius, Sophia; McGuigan, Michael R; Suchomel, Timothy J; Newton, Robert U

    2016-06-01

    This study assessed reliability of discrete ground reaction force (GRF) variables over multiple pitching trials, investigated the relationships between discrete GRF variables and pitch velocity (PV) and assessed the variability of the "force signature" or continuous force-time curve during the pitching motion of windmill softball pitchers. Intraclass correlation coefficient (ICC) for all discrete variables was high (0.86-0.99) while the coefficient of variance (CV) was low (1.4-5.2%). Two discrete variables were significantly correlated to PV; second vertical peak force (r(5)=0.81, p=0.03) and time between peak forces (r(5)=-0.79; p=0.03). High ICCs and low CVs support the reliability of discrete GRF and PV variables over multiple trials and significant correlations indicate there is a relationship between the ability to produce force and the timing of this force production with PV. The mean of all pitchers' curve-average standard deviation of their continuous force-time curves demonstrated low variability (CV=4.4%) indicating a repeatable and identifiable "force signature" pattern during this motion. As such, the continuous force-time curve in addition to discrete GRF variables should be examined in future research as a potential method to monitor or explain changes in pitching performance. PMID:26999033

  8. Comparison of natural and artificial forcing to study the dynamic behaviour of bell towers in low wind context by means of ground-based radar interferometry: the case of the Leaning Tower in Pisa

    The study of Cultural Heritage assets needs the application of non-destructive and non-invasive monitoring techniques. In particular, monuments and historical buildings which are open to the visitors and/or subject to important stress must be studied for their dynamic response. In the last 10 years the new ground-based radar interferometry technology has been developed allowing to monitor displacements from a point of sight far from the studied targets. It virtually provides a continuous mapping of displacements of the observed structures up to 10 µm with a range resolution of 0.75 m. In this paper, the application of ground-based interferometry on one very important historical building, the Leaning Tower of Pisa in Italy, is reported. The analysis of these kind of structures is important to catch their dynamic response to natural actions in general, and also to assess the effects due to pedestrian and users, and consequently to define functional capabilities and levels of acceptable dynamic stress. The studied structure was subject to artificial loading by synchronous movement of about 20 people. Artificial forcing led the structure to a resonance condition with the same frequency of the one due to the natural noise excitation, which was separately measured, and with an oscillation amplitude more than thirty times greater than the natural one (in conditions of weak wind). During the passive stages of the survey the recorded structural vibrations were very closed to the instrumental sensitivity, making difficult to distinguish vibration amplitudes amplifications of various segments at various heights. Through the spectral analysis of the acquired data it was possible to estimate the vibration frequencies of the first modal shapes of the structure along two orthogonal directions. The power spectra of the passive survey data have the same maximum frequency of the active but contain more noise at low frequency. (paper)

  9. Design and Operation of a Borehole Straddle Packer for Ground-Water Sampling and Hydraulic Testing of Discrete Intervals at U.S. Air Force Plant 6, Marietta, Georgia

    Holloway, Owen G.; Waddell, Jonathan P.

    2008-01-01

    A borehole straddle packer was developed and tested by the U.S. Geological Survey to characterize the vertical distribution of contaminants, head, and hydraulic properties in open-borehole wells as part of an ongoing investigation of ground-water contamination at U.S. Air Force Plant 6 (AFP6) in Marietta, Georgia. To better understand contaminant fate and transport in a crystalline bedrock setting and to support remedial activities at AFP6, numerous wells have been constructed that include long open-hole intervals in the crystalline bedrock. These wells can include several discontinuities that produce water, which may contain contaminants. Because of the complexity of ground-water flow and contaminant movement in the crystalline bedrock, it is important to characterize the hydraulic and water-quality characteristics of discrete intervals in these wells. The straddle packer facilitates ground-water sampling and hydraulic testing of discrete intervals, and delivery of fluids including tracer suites and remedial agents into these discontinuities. The straddle packer consists of two inflatable packers, a dual-pump system, a pressure-sensing system, and an aqueous injection system. Tests were conducted to assess the accuracy of the pressure-sensing systems, and water samples were collected for analysis of volatile organic compound (VOCs) concentrations. Pressure-transducer readings matched computed water-column height, with a coefficient of determination of greater than 0.99. The straddle packer incorporates both an air-driven piston pump and a variable-frequency, electronic, submersible pump. Only slight differences were observed between VOC concentrations in samples collected using the two different types of sampling pumps during two sampling events in July and August 2005. A test conducted to assess the effect of stagnation on VOC concentrations in water trapped in the system's pump-tubing reel showed that concentrations were not affected. A comparison was conducted

  10. Knee and ankle joint forces during steps and jumps down from two different heights.

    Nisell, R; Mizrah, J

    1988-05-01

    Two healthy subjects were filmed on TV-video when performing 14 different steps and jumps from two different heights (0·20 m and 0·43 m) onto two Kistler force platforms that recorded the reaction forces. The ankle and knee load moments and joint forces were calculated using a sagittal plane semi-dynamic biomechanical model. Steps with the ball of the foot from the lower height induced a vertical ground reaction force (Fz) close to 1 body weight (bw) and around 2 bw from the greater height. From the greater height the knee moments for the majority of the step-downs studied were about 100 Nm, which gave knee joint compressive forces of 4-7 bw. The ankle was exposed to loads of similar magnitude but not so much influenced by step height. The reasons why patients with knee pain prefer performing backward step-downs are discussed. PMID:23915840

  11. Effects of vascular infusion with a solution of saccharides; sodium chloride; phosphates; and vitamins C, E, or both on carcass traits, Warner-Bratzler shear force, and palatability traits of steaks and ground beef.

    Yancey, E J; Dikeman, M E; Addist, P B; Katsanidis, E; Pullen, M

    2002-07-01

    Three groups of 12 high percentage Charolais steers were slaughtered on three dates. Steers (n = 27) were infused immediately after exsanguination at 10% of BW with a solution containing saccharides, NaCl, and phosphates (MPSC solution; MPSC, Inc., St. Paul, MN) plus either 500 ppm vitamin C (MPSC+C), 500 ppm vitamin E (MPSC+E), or 500 ppm vitamin C plus 500 ppm vitamin E (MPSC+C+E). Noninfused controls (CON) were 9 steers. The longissimus thoracis (LT), semitendinosus (ST), and quadriceps femoris muscles were removed at 48-h postmortem, vacuum-packaged, and aged until 14-d postmortem. Steaks 2.54-cm thick were cut from the LT and ST. The quadriceps was utilized for ground-beef production. Infused steers had higher dressing percentages and heavier heart and liver weights (P 0.05) on USDA yield and quality-grade traits, LT and ST Warner-Bratzler shear force, descriptive-attribute traits, and freshly cooked steak flavor-profile traits. Vascular infusion had little effect on the flavor-profile traits of warmed-over steaks. Therefore, the results of our study indicate that vascular infusion with vitamins C, E, or C plus E can increase dressing percentage and organ weights, but have minimal effects on descriptive-attribute and flavor-profile sensory panel ratings. PMID:12162658

  12. Exact integral constraint requiring only the ground-state electron density as input on the exchange-correlation force - partial differential(V)(xc)(r)/partial differential(r) for spherical atoms.

    March, N H; Nagy, A

    2008-11-21

    Following some studies of integral(n)(r)inverted DeltaV(r)dr by earlier workers for the density functional theory (DFT) one-body potential V(r) generating the exact ground-state density, we consider here the special case of spherical atoms. The starting point is the differential virial theorem, which is used, as well as the Hiller-Sucher-Feinberg [Phys. Rev. A 18, 2399 (1978)] identity to show that the scalar quantity paralleling the above vector integral, namely, integral(n)(r) partial differential(V)(r)/partial differential(r)dr, is determined solely by the electron density n(0) at the nucleus for the s-like atoms He and Be. The force - partial differential(V)/ partial differential(r) is then related to the derivative of the exchange-correlation potential V(xc)(r) by terms involving only the external potential in addition to n(r). The resulting integral constraint should allow some test of the quality of currently used forms of V(xc)(r). The article concludes with results from the differential virial theorem and the Hiller-Sucher-Feinberg identity for the exact many-electron theory of spherical atoms, as well as for the DFT for atoms such as Ne with a closed p shell. PMID:19026052

  13. Insertion of the force applied to handles into centre of pressure calculation modifies the amplitude of centre of pressure shifts.

    Noé, Frédéric; Quaine, Franck

    2006-11-01

    This study examined situations where handles were used as additional postural supports. It aimed at determining the amplitude of centre of pressure (COP) shifts when considering or not the vertical handles reaction force. Eight healthy male subjects (24+/-6 years, body mass 65+/-5kg and height 175+/-7cm) voluntarily took part in the experiment. Subjects had to voluntarily rock on their heels or rise on their toe-tips while using handles. The vertical component of the handles forces and ground reaction force was measured and the shifts of the COP were calculated while inserting or not the handles forces. Significant differences were observed when comparing the amplitude of COP shifts calculated with or without the insertion of the handles forces. This study shows that the measurement of the handles forces should not be omitted, for a rigorous analysis of postural tasks performed in conditions including additional postural supports like handles. PMID:16300948

  14. Crystalline beam ground state

    In order to employ molecular dynamics (MD) methods, commonly used in condensed matter physics, we have derived the equations of motion for a beam of charged particles in the rotating rest frame of the reference particle. We include in the formalism that the particles are confined by the guiding and focusing magnetic fields, and that they are confined in a conducting vacuum pipe while interacting with each other via a Coulomb force. Numerical simulations using MD methods has been performed to obtain the equilibrium crystalline beam structure. The effect of the shearing force, centrifugal force, and azimuthal variation of the focusing strength are investigated. It is found that a constant gradient storage ring can not give a crystalline beam, but that an alternating-gradient (AG) structure can. In such a machine the ground state is, except for one-dimensional (1-D) crystals, time dependent. The ground state is a zero entropy state, despite the time-dependent, periodic variation of the focusing force. The nature of the ground state, similar to that found by Schiffer et al. depends upon the density and the relative focusing strengths in the transverse directions. At low density, the crystal is 1-D. As the density increases, it transforms into various kinds of 2-D and 3-D crystals. If the energy of the beam is higher than the transition energy of the machine, the crystalline structure can not be formed for lack of radial focusing

  15. Ground Wars

    Nielsen, Rasmus Kleis

    Political campaigns today are won or lost in the so-called ground war--the strategic deployment of teams of staffers, volunteers, and paid part-timers who work the phones and canvass block by block, house by house, voter by voter. Ground Wars provides an in-depth ethnographic portrait of two such...... of ground war tactics for how we understand political campaigns and what it means to participate in them. He shows how ground wars are waged using resources well beyond those of a given candidate and their staff. These include allied interest groups and civic associations, party-provided technical...... professionals. Yet he also quashes the romantic idea that canvassing is a purer form of grassroots politics. In today's political ground wars, Nielsen demonstrates, even the most ordinary-seeming volunteer knocking at your door is backed up by high-tech targeting technologies and party expertise. Ground Wars...

  16. Subatomic forces

    Inside the atom, particles interact through two forces which are never felt in the everyday world. But they may hold the key to the Universe. These ideas on subatomic forces are discussed with respect to the strong force, the electromagnetic force and the electroweak force. (author)

  17. Electroweak Force

    Murdin, P.

    2000-11-01

    The united force that encompasses the electromagnetic force and the weak nuclear force. The unification of these two forces is described by a theory that was devised during the 1960s by Sheldon Glashow, Steven Weinberg and Abdus Salam according to which, at high enough energies, the electromagnetic force and the weak nuclear interaction behave in exactly the same way....

  18. Methods for Addressing Uncertainty and Variability to Characterize Potential Health Risk From Trichloroethylene-Contaminated Ground Water Beale Air Force Base in California: Integration of Uncertainty and Variability in Pharmacokinetics and Dose-Response

    Bogen, K.T.

    1999-09-29

    Traditional estimates of health risk are typically inflated, particularly if cancer is the dominant endpoint and there is fundamental uncertainty as to mechanism(s) of action. Risk is more realistically characterized if it accounts for joint uncertainty and interindividual variability after applying a unified probabilistic approach to the distributed parameters of all (linear as well as nonlinear) risk-extrapolation models involved. Such an approach was applied to characterize risks to potential future residents posed by trichloroethylene (TCE) in ground water at an inactive landfill site on Beale Air Force Base in California. Variability and uncertainty were addressed in exposure-route-specific estimates of applied dose, in pharmacokinetically based estimates of route-specific metabolized fractions of absorbed TCE, and in corresponding biologically effective doses estimated under a genotoxic/linear (MA{sub g}) vs. a cytotoxic/nonlinear (MA{sub c}) mechanistic assumption for TCE-induced cancer. Increased risk conditional on effective dose was estimated under MA{sub G} based on seven rodent-bioassay data sets, and under MA, based on mouse hepatotoxicity data. Mean and upper-bound estimates of combined risk calculated by the unified approach were <10{sup -6} and <10{sup -4}, respectively, while corresponding estimates based on traditional deterministic methods were >10{sup -5} and >10{sup -4}, respectively. It was estimated that no TCE-related harm is likely occur due any plausible residential exposure scenario involving the site. The unified approach illustrated is particularly suited to characterizing risks that involve uncertain and/or diverse mechanisms of action.

  19. Methods for Addressing Uncertainty and Variability to Characterize Potential Health Risk from Trichloroethylene-Contaminated Ground Water at Beale Air Force Base in California:Integration of Uncertainty and Variability in Pharmacokinetics and Dose-Response

    Bogen, K T

    2001-05-24

    Traditional estimates of health risk are typically inflated, particularly if cancer is the dominant endpoint and there is fundamental uncertainty as to mechanism(s) of action. Risk is more realistically characterized if it accounts for joint uncertainty and interindividual variability within a systematic probabilistic framework to integrate the joint effects on risk of distributed parameters of all (linear as well as nonlinear) risk-extrapolation models involved. Such a framework was used to characterize risks to potential future residents posed by trichloroethylene (TCE) in ground water at an inactive landfill site on Beale Air Force Base in California. Variability and uncertainty were addressed in exposure-route-specific estimates of applied dose, in pharmacokinetically based estimates of route-specific metabolized fractions of absorbed TCE, and in corresponding biologically effective doses estimated under a genotoxic/linear (MA{sub G}) vs. a cytotoxic/nonlinear (MA{sub c}) mechanistic assumption for TCE-induced cancer. Increased risk conditional on effective dose was estimated under MA{sub G} based on seven rodent-bioassay data sets, and under MA{sub c} based on mouse hepatotoxicity data. Mean and upper-bound estimates of combined risk calculated by the unified approach were <10{sup -6} and 10{sup -4}, respectively, while corresponding estimates based on traditional deterministic methods were >10{sup -5} and 10{sup -4}, respectively. It was estimated that no TCE-related harm is likely to occur due to any plausible residential exposure scenario involving the site. The systematic probabilistic framework illustrated is particularly suited to characterizing risks that involve uncertain and/or diverse mechanisms of action.

  20. Análisis cuantitativo de la evolución post-quirúrgica de la rotura de ligamento cruzado anterior mediante el uso de la plataforma de fuerza - Quantitative analysis of the evolution of post-surgical anterior cruciate ligament rupture using force platform

    Vilar, JM; Morales M; Morales, I.; Montoya, A.; Rodríguez, O; Turco, V

    2010-01-01

    ResumenEl analisis cinético mediante plataforma de fuerza es un método objetivo de cuantificar el apoyo de los miembros en los animales domésticos.SummarySummaryKinetic análisis by jeans of force platforms is an objetive method to measure weight - bearing or ground reaction force (GRF).

  1. Análisis cuantitativo de la evolución post-quirúrgica de la rotura de ligamento cruzado anterior mediante el uso de la plataforma de fuerza - Quantitative analysis of the evolution of post-surgical anterior cruciate ligament rupture using force platform

    Vilar, JM

    2012-01-01

    Full Text Available ResumenEl analisis cinético mediante plataforma de fuerza es un método objetivo de cuantificar el apoyo de los miembros en los animales domésticos.SummaryKinetic análisis by jeans of force platforms is an objetive method to measure weight - bearing or ground reaction force (GRF.

  2. Assessment of Approximate Coupled-Cluster and Algebraic-Diagrammatic-Construction Methods for Ground- and Excited-State Reaction Paths and the Conical-Intersection Seam of a Retinal-Chromophore Model.

    Tuna, Deniz; Lefrancois, Daniel; Wolański, Łukasz; Gozem, Samer; Schapiro, Igor; Andruniów, Tadeusz; Dreuw, Andreas; Olivucci, Massimo

    2015-12-01

    As a minimal model of the chromophore of rhodopsin proteins, the penta-2,4-dieniminium cation (PSB3) poses a challenging test system for the assessment of electronic-structure methods for the exploration of ground- and excited-state potential-energy surfaces, the topography of conical intersections, and the dimensionality (topology) of the branching space. Herein, we report on the performance of the approximate linear-response coupled-cluster method of second order (CC2) and the algebraic-diagrammatic-construction scheme of the polarization propagator of second and third orders (ADC(2) and ADC(3)). For the ADC(2) method, we considered both the strict and extended variants (ADC(2)-s and ADC(2)-x). For both CC2 and ADC methods, we also tested the spin-component-scaled (SCS) and spin-opposite-scaled (SOS) variants. We have explored several ground- and excited-state reaction paths, a circular path centered around the S1/S0 surface crossing, and a 2D scan of the potential-energy surfaces along the branching space. We find that the CC2 and ADC methods yield a different dimensionality of the intersection space. While the ADC methods yield a linear intersection topology, we find a conical intersection topology for the CC2 method. We present computational evidence showing that the linear-response CC2 method yields a surface crossing between the reference state and the first response state featuring characteristics that are expected for a true conical intersection. Finally, we test the performance of these methods for the approximate geometry optimization of the S1/S0 minimum-energy conical intersection and compare the geometries with available data from multireference methods. The present study provides new insight into the performance of linear-response CC2 and polarization-propagator ADC methods for molecular electronic spectroscopy and applications in computational photochemistry. PMID:26642989

  3. Force enhancement and force depression in a modified muscle model used for muscle activation prediction.

    Kosterina, Natalia; Wang, Ruoli; Eriksson, Anders; Gutierrez-Farewik, Elena M

    2013-08-01

    This article introduces history-dependent effects in a skeletal muscle model applied to dynamic simulations of musculoskeletal system motion. Force depression and force enhancement induced by active muscle shortening and lengthening, respectively, represent muscle history effects. A muscle model depending on the preceding contractile events together with the current parameters was developed for OpenSim software, and applied in simulations of standing heel-raise and squat movements. Muscle activations were computed using joint kinematics and ground reaction forces recorded from the motion capture of seven individuals. In the muscle-actuated simulations, a modification was applied to the computed activation, and was compared to the measured electromyography data. For the studied movements, the history gives a small but visible effect to the muscular force trace, but some parameter values must be identified before the exact magnitude can be analysed. The muscle model modification improves the existing muscle models and gives a more accurate description of underlying forces and activations in musculoskeletal system movement simulations. PMID:23561824

  4. A simple method for measuring power, force, velocity properties, and mechanical effectiveness in sprint running.

    Samozino, P; Rabita, G; Dorel, S; Slawinski, J; Peyrot, N; Saez de Villarreal, E; Morin, J-B

    2016-06-01

    This study aimed to validate a simple field method for determining force- and power-velocity relationships and mechanical effectiveness of force application during sprint running. The proposed method, based on an inverse dynamic approach applied to the body center of mass, estimates the step-averaged ground reaction forces in runner's sagittal plane of motion during overground sprint acceleration from only anthropometric and spatiotemporal data. Force- and power-velocity relationships, the associated variables, and mechanical effectiveness were determined (a) on nine sprinters using both the proposed method and force plate measurements and (b) on six other sprinters using the proposed method during several consecutive trials to assess the inter-trial reliability. The low bias (running. PMID:25996964

  5. Survival of the Fittest: Competitive Co-crystal Reactions in the Ball Mill.

    Fischer, Franziska; Joester, Maike; Rademann, Klaus; Emmerling, Franziska

    2015-10-12

    The driving forces triggering the formation of co-crystals under milling conditions were investigated by using a set of multicomponent competitive milling reactions. In these reactions, different active pharmaceutical ingredients were ground together with a further compound acting as coformer. The study was based on new co-crystals including the coformer anthranilic acid. The results of the competitive milling reactions indicate that the formation of co-crystals driven by intermolecular recognition are influenced and inhibited by kinetic aspects including the formation of intermediates and the stability of the reactants. PMID:26332316

  6. A hub dynamometer for measurement of wheel forces in off-road bicycling.

    De Lorenzo, D S; Hull, M L

    1999-02-01

    A dynamometric hubset that measures the two ground contact force components acting on a bicycle wheel in the plane of the bicycle during off-road riding while either coasting or braking was designed, constructed, and evaluated. To maintain compatibility with standard mountain bike construction, the hubs use commercially available shells with modified, strain gage-equipped axles. The axle strain gages are sensitive to forces acting in the radial and tangential directions, while minimizing sensitivity to transverse forces, steering moments, and variations in the lateral location of the center of pressure. Static calibration and a subsequent accuracy check that computed differences between applied and apparent loads developed during coasting revealed root mean squared errors of 1 percent full-scale or less (full-scale load = 4500 N). The natural frequency of the rear hub with the wheel attached exceeded 350 Hz. These performance capabilities make the dynamometer useful for its intended purpose during coasting. To demonstrate this usefulness, sample ground contact forces are presented for a subject who coasted downhill over rough terrain. The dynamometric hubset can also be used to determine ground contact forces during braking providing that the brake reaction force components are known. However, compliance of the fork can lead to high cross-sensitivity and corresponding large (> 5 percent FS) measurement errors at the front wheel. PMID:10080099

  7. Grounded Intersectionality

    Marfelt, Mikkel Mouritz

    2016-01-01

    Purpose – The purpose of this paper is to build on contemporary intersectional literature to develop a grounded methodological framework for the study of social differences. Design/methodology/approach – A systematic literature review serves as the foundation for a discussion of the challenges as...

  8. Ground Zero.

    Lozada, Marlene

    1998-01-01

    Many public school districts have adopted a policy of zero tolerance toward drug use, weapon possession, and sexual harassment on school grounds. Although a study by the National Center for Education Statistics reported no evidence that zero tolerance policies have lowered school crime rates, prominent education groups favor them. (JOW)

  9. Labor Force

    Occupational Outlook Quarterly, 2012

    2012-01-01

    The labor force is the number of people ages 16 or older who are either working or looking for work. It does not include active-duty military personnel or the institutionalized population, such as prison inmates. Determining the size of the labor force is a way of determining how big the economy can get. The size of the labor force depends on two…

  10. Pseudo force acting between bodies

    Baruah, Abhinav Ray; Deva, Anish; Sarma, Arun

    It has been shown that a non-contact force acts between two macroscopic physical objects held close together, which is not associated with the gravitational and electrostatic force. An experiment was conducted with objects of different mass, material and geometry to find the magnitude and properties of this apparent or pseudo force. The order of magnitude was found to be 10-5 and it remained constant for all types of objects while only the coefficient increased as the distance between the objects reduced. It only started acting at small distances and failed to make a body move if it experienced static friction from any contact surface. The nature of the force was found to be attractive as well as repulsive. Due to gravitation being a solely attractive force, it was eliminated as a possible reason for the pseudo force. The experiment was performed twice, once by grounding the apparatus and then again without grounding. The order of the force remained the same for both cases. As the test objects were held by hand, they were grounded through the human body. Also, none of the objects used were in contact with each other for the duration of this work, preventing any contact electrification. Due to these factors, the force was not considered electrostatic in nature.

  11. Dispersion Forces

    Buhmann, Stefan Yoshi

    2012-01-01

    In this book, a modern unified theory of dispersion forces on atoms and bodies is presented which covers a broad range of advanced aspects and scenarios. Macroscopic quantum electrodynamics is shown to provide a powerful framework for dispersion forces which allows for discussing general properties like their non-additivity and the relation between microscopic and macroscopic interactions. It is demonstrated how the general results can be used to obtain dispersion forces on atoms in the presence of bodies of various shapes and materials. Starting with a brief recapitulation of volume I, this volume II deals especially with bodies of irregular shapes, universal scaling laws, dynamical forces on excited atoms, enhanced forces in cavity quantum electrodynamics, non-equilibrium forces in thermal environments and quantum friction. The book gives both the specialist and those new to the field a thorough overview over recent results in the field. It provides a toolbox for studying dispersion forces in various contex...

  12. Ground Pollution Science

    This book deals with ground pollution science and soil science, classification of soil and fundamentals, ground pollution and human, ground pollution and organic matter, ground pollution and city environment, environmental problems of the earth and ground pollution, soil pollution and development of geological features of the ground, ground pollution and landfill of waste, case of measurement of ground pollution.

  13. Coaxial Atomic Force Microscope Tweezers

    Brown, K A; Westervelt, R M

    2010-01-01

    We demonstrate coaxial atomic force microscope (AFM) tweezers that can trap and place small objects using dielectrophoresis (DEP). An attractive force is generated at the tip of a coaxial AFM probe by applying a radio frequency voltage between the center conductor and a grounded shield; the origin of the force is found to be DEP by measuring the pull-off force vs. applied voltage. We show that the coaxial AFM tweezers (CAT) can perform three dimensional assembly by picking up a specified silica microsphere, imaging with the microsphere at the end of the tip, and placing it at a target destination.

  14. Coaxial atomic force microscope tweezers

    Brown, K. A.; Aguilar, J. A.; Westervelt, R. M.

    2010-03-01

    We demonstrate coaxial atomic force microscope (AFM) tweezers that can trap and place small objects using dielectrophoresis (DEP). An attractive force is generated at the tip of a coaxial AFM probe by applying a radio frequency voltage between the center conductor and a grounded shield; the origin of the force is found to be DEP by measuring the pull-off force versus applied voltage. We show that the coaxial AFM tweezers can perform three-dimensional assembly by picking up a specified silica microsphere, imaging with the microsphere at the end of the tip, and placing it at a target destination.

  15. Force sensing

    Sanders, David

    2007-01-01

    A young child can explore and learn and compensate for unknown dynamics by prodding, pushing, touching, grasping and feeling. Force sensing and software research could soon allow artificial mechanisms to do the same. Force sensing has its roots in strain gauges, piezoelectrics, Wheatstone bridges, automation, robotics, grippers and virtual reality. That force sensing research has now become commonplace and has expanded from those roots to include so much more: video games, athletic equipment,...

  16. Kinetics of the forelimb in horses circling on different ground surfaces at the trot.

    Chateau, Henry; Camus, Mathieu; Holden-Douilly, Laurène; Falala, Sylvain; Ravary, Bérangère; Vergari, Claudio; Lepley, Justine; Denoix, Jean-Marie; Pourcelot, Philippe; Crevier-Denoix, Nathalie

    2013-12-01

    Circling increases the expression of distal forelimb lameness in the horse, depending on rein, diameter and surface properties of the circle. However, there is limited information about the kinetics of horses trotting on circles. The aim of this study was to quantify ground reaction force (GRF) and moments in the inside and outside forelimb of horses trotting on circles and to compare the results obtained on different ground surfaces. The right front hoof of six horses was equipped with a dynamometric horseshoe, allowing the measurement of 3-dimensional GRF, moments and trajectory of the centre of pressure. The horses were lunged at slow trot (3 m/s) on right and left 4 m radius circles on asphalt and on a fibre sand surface. During circling, the inside forelimb produced a smaller peak vertical force and the stance phase was longer in comparison with the outside forelimb. Both right and left circling produced a substantial transversal force directed outwards. On a soft surface (sand fibre), the peak transversal force and moments around the longitudinal and vertical axes of the hoof were significantly decreased in comparison with a hard surface (asphalt). Sinking of the lateral or medial part of the hoof in a more compliant surface enables reallocation of part of the transversal force into a proximo-distal force, aligned with the limb axis, thus limiting extrasagittal stress on the joints. PMID:24511634

  17. 'Grounded' Politics

    Schmidt, Garbi

    2012-01-01

    play within one particular neighbourhood: Nørrebro in the Danish capital, Copenhagen. The article introduces the concept of grounded politics to analyse how groups of Muslim immigrants in Nørrebro use the space, relationships and history of the neighbourhood for identity political statements....... The article further describes how national political debates over the Muslim presence in Denmark affect identity political manifestations within Nørrebro. By using Duncan Bell’s concept of mythscape (Bell, 2003), the article shows how some political actors idealize Nørrebro’s past to contest the present...

  18. Lorentz-force approach to the Casimir force

    An approach to the problem of the Casimir force on magnetodielectric bodies is outlined, which is based on the calculation of the ground-state Lorentz force acting on the polarization and magnetization charges and currents that constitute the bodies within the framework of linear, macroscopic electrodynamics. As an application, planar structures are considered and a correct generalization of Casimir's original formula to the case where the two highly reflecting plates are embedded in a medium is given

  19. Lorentz-force approach to the Casimir force

    Raabe, Christian; Welsch, Dirk-Gunnar [Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, D-07743 Jena (Germany)

    2006-04-01

    An approach to the problem of the Casimir force on magnetodielectric bodies is outlined, which is based on the calculation of the ground-state Lorentz force acting on the polarization and magnetization charges and currents that constitute the bodies within the framework of linear, macroscopic electrodynamics. As an application, planar structures are considered and a correct generalization of Casimir's original formula to the case where the two highly reflecting plates are embedded in a medium is given.

  20. Strong Force

    Without the strong force, there could be no life. The carbon in living matter is synthesised in stars via the strong force. Lighter atomic nuclei become bound together in a process called nuclear fusion. A minor change in this interaction would make life impossible. As its name suggests, the strong force is the most powerful of the 4 forces, yet its sphere of influence is limited to within the atomic nucleus. Indeed it is the strong force that holds together the quarks inside the positively charged protons. Without this glue, the quarks would fly apart repulsed by electromagnetism. In fact, it is impossible to separate 2 quarks : so much energy is needed, that a second pair of quarks is produced. Text for the interactive: Can you pull apart the quarks inside a proton?

  1. Weak Force

    Without the weak force, the sun wouldn't shine. The weak force causes beta decay, a form of radioactivity that triggers nuclear fusion in the heart of the sun. The weak force is unlike other forces: it is characterised by disintegration. In beta decay, a down quark transforms into an up quark and an electron is emitted. Some materials are more radioactive than others because the delicate balance between the strong force and the weak force varies depending on the number of particles in the atomic nucleus. We live in the midst of a natural radioactive background that varies from region to region. For example, in Cornwall where there is a lot of granite, levels of background radiation are much higher than in the Geneva region. Text for the interactive: Move the Geiger counter to find out which samples are radioactive - you may be surprised. It is the weak force that is responsible for the Beta radioactivity here. The electrons emitted do not cross the plastic cover. Why do you think there is some detected radioa...

  2. Modelling of Muscle Force Distributions During Barefoot and Shod Running

    Sinclair Jonathan

    2015-09-01

    Full Text Available Research interest in barefoot running has expanded considerably in recent years, based around the notion that running without shoes is associated with a reduced incidence of chronic injuries. The aim of the current investigation was to examine the differences in the forces produced by different skeletal muscles during barefoot and shod running. Fifteen male participants ran at 4.0 m·s-1 (± 5%. Kinematics were measured using an eight camera motion analysis system alongside ground reaction force parameters. Differences in sagittal plane kinematics and muscle forces between footwear conditions were examined using repeated measures or Freidman’s ANOVA. The kinematic analysis showed that the shod condition was associated with significantly more hip flexion, whilst barefoot running was linked with significantly more flexion at the knee and plantarflexion at the ankle. The examination of muscle kinetics indicated that peak forces from Rectus femoris, Vastus medialis, Vastus lateralis, Tibialis anterior were significantly larger in the shod condition whereas Gastrocnemius forces were significantly larger during barefoot running. These observations provide further insight into the mechanical alterations that runners make when running without shoes. Such findings may also deliver important information to runners regarding their susceptibility to chronic injuries in different footwear conditions.

  3. Lower extremity corrective reactions to slip events.

    Cham, R; Redfern, M S

    2001-11-01

    A significant number of injuries in the workplace is attributed to slips and falls. Biomechanical responses to actual slip events determine whether the outcome of a slip will be recovery or a fall. The goal of this study was to examine lower extremity joint moments and postural adjustments for experimental evidence of corrective strategies evoked during slipping in an attempt to prevent falling. Sixteen subjects walked onto a possibly oily vinyl tile floor, while ground reaction forces and body motion were recorded at 350 Hz. The onset of corrective reactions by the body in an attempt to recover from slips became evident at about 25% of stance and continued until about 45% into stance, i.e. on average between 190 and 350 ms after heel contact. These reactions included increased flexion moment at the knee and extensor activity at the hip. The ankle, on the other hand, acted as a passive joint (no net moment) during fall trials. Joint kinematics showed increased knee flexion and forward rotation of the shank in an attempt to bring the foot back towards the body. Once again, the ankle kinematics appeared to play a less dominant role (compared to the knee) in recovery attempts. This study indicates that humans generate corrective reactions to slips that are different than previously reported responses to standing perturbations translating the supporting surface. PMID:11672718

  4. The amazing normal forces

    Petrache, Horia I

    2012-01-01

    This manuscript is written for students in introductory physics classes to address some of the common difficulties and misconceptions of the normal force, especially the relationship between normal and friction forces. Accordingly, it is intentionally informal and conversational in tone to teach students how to build an intuition to complement mathematical formalism. This is accomplished by beginning with common and everyday experience and then guiding students toward two realizations: (i) That real objects are deformable even when deformations are not easily visible, and (ii) that the relation between friction and normal forces follows from the action-reaction principle. The traditional formulae under static and kinetic conditions are then analyzed to show that peculiarity of the normal-friction relationship follows readily from observations and knowledge of physics principles.

  5. Army ground robotics research program

    Bornstein, Jonathan A.

    2002-07-01

    The U.S. Army has committed to a paradigm shift in the way future ground military operations will be conducted. It envisions highly mobile, lethal, and survivable forces that seamlessly combine manned and unmanned elements. To support this vision, the U.S. Army Research Laboratory, together with an alliance of government, industrial and academic organizations, has embarked upon a concerted research program focusing upon development of the technologies required for autonomous ground mobility by unmanned systems. This paper will discuss technical activities of the past year and research directions for the future.

  6. Effect of increased pushoff during gait on hip joint forces.

    Lewis, Cara L; Garibay, Erin J

    2015-01-01

    Anterior acetabular labral tears and anterior hip pain may result from high anteriorly directed forces from the femur on the acetabulum. While providing more pushoff is known to decrease sagittal plane hip moments, it is unknown if this gait modification also decreases hip joint forces. The purpose of this study was to determine if increasing pushoff decreases hip joint forces. Nine healthy subjects walked on an instrumented force treadmill at 1.25 m/s under two walking conditions. For the natural condition, subjects were instructed to walk as they normally would. For the increased pushoff condition, subjects were instructed to "push more with your foot when you walk". We collected motion data of markers placed on the subjects' trunk and lower extremities to capture trunk and leg kinematics and ground reaction force data to determine joint moments. Data were processed in Visual3D to produce the inverse kinematics and model scaling files. In OpenSim, the generic gait model (Gait2392) was scaled to the subject, and hip joint forces were calculated for the femur on the acetabulum after computing the muscle activations necessary to reproduce the experimental data. The instruction to "push more with your foot when you walk" reduced the maximum hip flexion and extension moment compared to the natural condition. The average reduction in the hip joint forces were 12.5%, 3.2% and 9.6% in the anterior, superior and medial directions respectively and 2.3% for the net resultant force. Increasing pushoff may be an effective gait modification for people with anterior hip pain. PMID:25468661

  7. Euthanasia: above ground, below ground.

    Magnusson, R S

    2004-10-01

    The key to the euthanasia debate lies in how best to regulate what doctors do. Opponents of euthanasia frequently warn of the possible negative consequences of legalising physician assisted suicide and active euthanasia (PAS/AE) while ignoring the covert practice of PAS/AE by doctors and other health professionals. Against the background of survey studies suggesting that anything from 4% to 10% of doctors have intentionally assisted a patient to die, and interview evidence of the unregulated, idiosyncratic nature of underground PAS/AE, this paper assesses three alternatives to the current policy of prohibition. It argues that although legalisation may never succeed in making euthanasia perfectly safe, legalising PAS/AE may nevertheless be safer, and therefore a preferable policy alternative, to prohibition. At a minimum, debate about harm minimisation and the regulation of euthanasia needs to take account of PAS/AE wherever it is practised, both above and below ground. PMID:15467073

  8. A superellipsoid-plane model for simulating foot-ground contact during human gait.

    Lopes, D S; Neptune, R R; Ambrósio, J A; Silva, M T

    2016-07-01

    Musculoskeletal models and forward dynamics simulations of human movement often include foot-ground interactions, with the foot-ground contact forces often determined using a constitutive model that depends on material properties and contact kinematics. When using soft constraints to model the foot-ground interactions, the kinematics of the minimum distance between the foot and planar ground needs to be computed. Due to their geometric simplicity, a considerable number of studies have used point-plane elements to represent these interacting bodies, but few studies have provided comparisons between point contact elements and other geometrically based analytical solutions. The objective of this work was to develop a more general-purpose superellipsoid-plane contact model that can be used to determine the three-dimensional foot-ground contact forces. As an example application, the model was used in a forward dynamics simulation of human walking. Simulation results and execution times were compared with a point-like viscoelastic contact model. Both models produced realistic ground reaction forces and kinematics with similar computational efficiency. However, solving the equations of motion with the surface contact model was found to be more efficient (~18% faster), and on average numerically ~37% less stiff. The superellipsoid-plane elements are also more versatile than point-like elements in that they allow for volumetric contact during three-dimensional motions (e.g. rotating, rolling, and sliding). In addition, the superellipsoid-plane element is geometrically accurate and easily integrated within multibody simulation code. These advantages make the use of superellipsoid-plane contact models in musculoskeletal simulations an appealing alternative to point-like elements. PMID:26325481

  9. Flexible propulsors in ground effect

    We present experimental evidence for the hydrodynamic benefits of swimming ‘in ground effect’, that is, near a solid boundary. This situation is common to fish that swim near the substrate, especially those that are dorsoventrally compressed, such as batoids and flatfishes. To investigate flexible propulsors in ground effect, we conduct force measurements and particle image velocimetry on flexible rectangular panels actuated at their leading edge near the wall of a water channel. For a given actuation mode, the panels swim faster near the channel wall while maintaining the same propulsive economy. In conditions producing net thrust, panels produce more thrust near the ground. When operating in resonance, swimming near the ground can also increase propulsive efficiency. Finally, the ground can act to suppress three-dimensional modes, thereby increasing thrust and propulsive efficiency. The planform considered here is non-biological, but the hydrodynamic benefits are likely to apply to more complex geometries, especially those where broad flexible propulsors are involved such as fish bodies and fins. Such fish could produce more thrust by swimming near the ground, and in some cases do so more efficiently. (paper)

  10. Active media under rotational forcing.

    Pérez-Villar, Vicente; Porteiro, Jose L F; Muñuzuri, Alberto P

    2006-10-01

    The bubble-free Belousov-Zhabotinsky reaction has been used to study the effects of centrifugal forces on autowave propagation. The reaction parameters were chosen such that the system oscillates naturally creating target waves. In the present study, the system was forced to rotate with a constant velocity around a central axis. In studying the effects of such a forcing on the system, we focused on target dynamics. The system reacts to this forcing in different ways, the most spectacular being a dramatic increase in the period of the target, the effect growing stronger as we move away from the center of rotation. A numerical study was carried out using the two-variable Oregonator model, modified to include convective effects through the diffusion coefficient. The numerical results showed a good qualitative agreement with those of the experiments. PMID:17155149

  11. Level locomotion in wood ants: evidence for grounded running.

    Reinhardt, Lars; Blickhan, Reinhard

    2014-07-01

    In order to better understand the strategies of locomotion in small insects, we have studied continuous level locomotion of the wood ant species Formica polyctena. We determined the three-dimensional centre of mass kinematics during the gait cycle and recorded the ground reaction forces of single legs utilising a self-developed test site. Our findings show that the animals used the same gait dynamics across a wide speed range without dissolving the tripodal stride pattern. To achieve higher velocities, the ants proportionally increased stride length and stepping frequency. The centre of mass energetics indicated a bouncing gait, in which horizontal kinetic and gravitational potential energy fluctuated in close phase. We determined a high degree of compliance especially in the front legs, as the effective leg length was nearly halved during the contact phase. This leads to only small vertical oscillations of the body, which are important in maintaining ground contact. Bouncing gaits without aerial phases seem to be a common strategy in small runners and can be sufficiently described by the bipedal spring-loaded inverted pendulum model. Thus, with our results, we provide evidence that wood ants perform 'grounded running'. PMID:24744414

  12. Muscle activation and estimated relative joint force during running with weight support on a lower-body positive pressure treadmill

    Jensen, Bente Rona; Hovgaard-Hansen, Line; Cappelen, Katrine Louise

    2016-01-01

    Running on a lower-body positive pressure (LBPP) treadmill allows effects of weight support on leg muscle activation to be assessed systematically, and has the potential to facilitate rehabilitation and prevent overloading. The aim was to study the effect of running with weight support on leg......, while activity of biceps femoris muscle remained unchanged. Unweighting with LBPP reduced estimated joint force significantly although less than proportional to the degree of weight support (ankle). It was concluded that leg muscle activation adapted to the new biomechanical environment, and the effect...... muscle activation and to estimate relative knee and ankle joint forces. Runners performed 6-min running sessions at 2.22 m/s and 3.33 m/s, at 100, 80, 60, 40 and 20% body-weight (BW). Surface EMG, ground reaction force and running characteristics were measured. Relative knee and ankle joint forces were...

  13. Subject-specific knee joint geometry improves predictions of medial tibiofemoral contact forces.

    Gerus, Pauline; Sartori, Massimo; Besier, Thor F; Fregly, Benjamin J; Delp, Scott L; Banks, Scott A; Pandy, Marcus G; D'Lima, Darryl D; Lloyd, David G

    2013-11-15

    Estimating tibiofemoral joint contact forces is important for understanding the initiation and progression of knee osteoarthritis. However, tibiofemoral contact force predictions are influenced by many factors including muscle forces and anatomical representations of the knee joint. This study aimed to investigate the influence of subject-specific geometry and knee joint kinematics on the prediction of tibiofemoral contact forces using a calibrated EMG-driven neuromusculoskeletal model of the knee. One participant fitted with an instrumented total knee replacement walked at a self-selected speed while medial and lateral tibiofemoral contact forces, ground reaction forces, whole-body kinematics, and lower-limb muscle activity were simultaneously measured. The combination of generic and subject-specific knee joint geometry and kinematics resulted in four different OpenSim models used to estimate muscle-tendon lengths and moment arms. The subject-specific geometric model was created from CT scans and the subject-specific knee joint kinematics representing the translation of the tibia relative to the femur was obtained from fluoroscopy. The EMG-driven model was calibrated using one walking trial, but with three different cost functions that tracked the knee flexion/extension moments with and without constraint over the estimated joint contact forces. The calibrated models then predicted the medial and lateral tibiofemoral contact forces for five other different walking trials. The use of subject-specific models with minimization of the peak tibiofemoral contact forces improved the accuracy of medial contact forces by 47% and lateral contact forces by 7%, respectively compared with the use of generic musculoskeletal model. PMID:24074941

  14. Transition States from Empirical Force Fields

    Jensen, Frank; Norrby, Per-Ola

    2003-01-01

    This is an overview of the use of empirical force fields in the study of reaction mechanisms. EVB-type methods (including RFF and MCMM) produce full reaction surfaces by mixing, in the simplest case, known force fields describing reactants and products. The SEAM method instead locates approximate...... transition structures by energy minimization along the intersection of the component force fields. The TSFF approach (including Q2MM) designs a new force field mimicking the transition structure as an energy minimum. The scope and applicability of the various methods are compared....

  15. Design Optimization of Ground Clearance of Domestic Cars

    Debojyoti Mitra

    2010-07-01

    Full Text Available Drag and lift forces plays a vital role in the performance and stability of vehicles. Less drag means less fuel consumption and hence less vehicular pollution. Also, lower lift force means higher chance of adhesion of the car body with the ground causing less overturning of the vehicle, which improves the vehicle performance. Both drag and lift forces can be manipulated by varying the ground clearance of the cars. The present study concentrates on studying the effect of ground clearance on these aerodynamic forces experimentally. Wind tunnel studies with a notch-back car model revealed increase in drag and decrease in lift with increase in ground clearance. Therefore, optimization is required for designing the best ground clearance and a preferable value of the same is thus obtained.

  16. EMG and force production of the flexor hallucis longus muscle in isometric plantarflexion and the push-off phase of walking.

    Péter, Annamária; Hegyi, András; Stenroth, Lauri; Finni, Taija; Cronin, Neil J

    2015-09-18

    Large forces are generated under the big toe in the push-off phase of walking. The largest flexor muscle of the big toe is the flexor hallucis longus (FHL), which likely contributes substantially to these forces. This study examined FHL function at different levels of isometric plantarflexion torque and in the push-off phase at different speeds of walking. FHL and calf muscle activity were measured with surface EMG and plantar pressure was recorded with pressure insoles. FHL activity was compared to the activity of the calf muscles. Force and impulse values were calculated under the big toe, and were compared to the entire pressed area of the insole to determine the relative contribution of big toe flexion forces to the ground reaction force. FHL activity increased with increasing plantarflexion torque level (F=2.8, P=0.024) and with increasing walking speed (F=11.608, Pcalf muscles, highlighting the task-dependant behaviour of FHL. PMID:26100463

  17. Estimation of joint forces and moments for the in-run and take-off in ski jumping based on measurements with wearable inertial sensors.

    Logar, Grega; Munih, Marko

    2015-01-01

    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. PMID:25985167

  18. Estimation of aerosol radiative forcing over an aged-background aerosol feature during advection and non-advection events using a ground-based data obtained from a Prede Skyradiometer observation

    Ningombam, Shantikumar S.; Bagare, S. P.; Khatri, P.; Sohn, B. J.; Song, H.-J.

    2015-10-01

    Estimation of aerosol radiative forcing (ARF) was performed using a radiative transfer model (Rstar6b) along with physical and optical parameters of aerosols obtained from sky radiometer observation over Indian Astronomical Observatory (IAO), Hanle, Ladakh, during 2008-2010 from dust, anthropogenic, and aged background observing conditions. ARF was estimated at the top of the atmosphere (TOA), in the atmosphere, and at the surface during the three observing conditions. During dust and anthropogenic events, average aerosol optical depth (AOD at 500 nm) went up to 0.24 from the aged background observing condition 0.04. Such enhancement of AOD is associated by the combination of desert-dust and anthropogenic aerosols transported from distant sources as noticed from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). Such three types of aerosols are also identified from the observed properties of single scattering albedo (SSA), aerosol asymmetry (AS) parameter, and aerosol size distribution. The estimated ARFs at TOA, at the surface, and in atmosphere are - 3.73, - 6.82, and 3.40 Wm- 2, respectively during the dust advection period. On the contrary, the respective ARFs during the aged background observing condition are - 1.50, - 2.22, and 0.70 Wm- 2, respectively. A significant difference of spectral AOD is observed during dust, anthropogenic, and aged background observing conditions. Ångström exponent (AE) decreases from 1.05 in the aged background observing condition to 0.40 in the dust event. A significant difference of coarse-fine mode volume distribution is also observed between the dust and the anthropogenic cases. Further, the study reveals high aerosols induced during the dust and the anthropogenic episodes caused warming at atmosphere and cooling at surface which collectively may affect the local atmospheric circulation.

  19. Impact Forces of Walking and Running at the Same Intensity.

    Swain, David P; Kelleran, Kyle J; Graves, Melani S; Morrison, Steven

    2016-04-01

    Moderate-intensity walking (horizontal, WH), vigorous-intensity walking (incline, WI), and vigorous-intensity running (horizontal, R) were compared. The hypothesis is that running creates greater loading forces than walking even at the same aerobic intensity. Young adults (10 M and 10 F; age, 22.8 ± 0.5 years) performed 3 exercise trials in a counter-balanced order: walking 5.5 kph at 0% grade (WH); walking 5.5 kph at 11% (WI); and running at 8.0 kph at 0% (R). Oxygen consumption (V[Combining Dot Above]O2), step frequency, peak vertical ground reaction force (VGRF), and vertical force loading rate were recorded during the last 5 minutes of each trial. Results are mean ± SE. Net V[Combining Dot Above]O2 during WH (10.5 ± 0.3 ml·min·kg) was significantly less than WI (26.3 ± 0.3) and R (25.1 ± 0.7 ml·min·kg). Step frequency was significantly greater during R (163 ± 1.5 steps per minute) than both walking conditions (WH, 128 ± 1.0 steps per minute; WI, 126 ± 1.2 steps per minute). Peak VGRF was significantly greater during running (844 ± 47 N) than both walking conditions (WH, 581 ± 27 N; WI, 565 ± 28 N). Force loading rate was significantly greater with R (8,214 ± 26 N·s) than WH (6,497 ± 15 N·s ) and WI (5,699 ± 16 N·s ), with WH > WI. Vigorous-intensity walking produced no greater loading forces than moderate-intensity walking. However, running at a vigorous intensity produced substantially greater loading forces than walking of the same intensity. These findings suggest that vigorous aerobic exercise may be performed without elevated orthopedic stress, depending on the mode prescribed. PMID:27003452

  20. Seismic Analysis of Elevated Water Storage Tanks Subjected to Six Correlated Ground Motion Components

    L. Kalani Sarokolayi

    2013-01-01

    Full Text Available In this work, rotational components of ground motion acceleration were defined according toimproved method from the corresponding available translational components based on transversely isotropicelastic wave propagation in the soil. With such improvement, it becomes possible to consider frequencydependent wave velocities on rotational components of ground motion. For this purpose, three translationalcomponents of El Centro earthquake (24 January 1951 were adopted to generate their relative rotationalcomponents based on SV and SH wave incidence by Fast Fourier transform with 4096 discrete frequencies.The translational and computed rotational motions were then applied to the concrete elevated water storagetanks with different structural characteristics and water elevations. The finite element method is used for thenonlinear analysis of water storage tanks considering the fluid-structure interaction using Lagrangian-Lagrangian approach and the concrete material nonlinearities have been taken into account through William-Warnke model. The nonlinear response of these structures considering the six components of ground motionshowed that the rotational components of ground motion can increase or decrease the maximum displacementand reaction force of the structure. These variations are depending on the frequency of structure andpredominant frequencies of translational and rotational components of ground motion.

  1. The Introduction of Fields in Relation to Force

    Brunt, Marjorie; Brunt, Geoff

    2012-01-01

    The introduction of force at age 14-16 years is considered, starting with elementary student experiments using magnetic force fields. The meaningless use of terms such as "action" and "reaction", or "agent" and "receiver" is discussed. (Contains 6 figures.)

  2. NUMERICAL ANALYSIS OF THE GROUND EFFECT ON INSECT HOVERING

    GAO Tong; LIU Nan-sheng; LU Xi-yun

    2008-01-01

    The ground effect on insect hovering is investigated using an immersed boundary-lattice Boltzmann method to solve the two-dimensional incompressible Navier-Stokes equations. A virtual model of an elliptic foil with oscillating translation and rotation near a ground is used. The objective of this study is to deal with the ground effect on the unsteady forces and vortical structures and to get the physical insights in the relevant mechanisms. Two typical insect hovering modes, I.e., normal and dragonfly hovering mode, are examined. Systematic computations have been carried out for some parameters, and the ground effect on the unsteady forces and vortical structures is analyzed.

  3. Ground water and energy

    1980-11-01

    This national workshop on ground water and energy was conceived by the US Department of Energy's Office of Environmental Assessments. Generally, OEA needed to know what data are available on ground water, what information is still needed, and how DOE can best utilize what has already been learned. The workshop focussed on three areas: (1) ground water supply; (2) conflicts and barriers to ground water use; and (3) alternatives or solutions to the various issues relating to ground water. (ACR)

  4. Ground Assisted Onboard Planning Autonomy with VAMOS

    Wörle, Maria Theresia; Lenzen, Christoph

    2013-01-01

    The typical ground based mission planning system for a low earth satellite mission has one major drawback: The reaction time to onboard detected events includes at least the two upcoming ground station contacts. To address this disadvantage, DLR/GSOC implements the software experiment VAMOS as part of the FireBIRD mission, in which mission planning autonomy will be transferred to the spacecraft up to some extent. This paper presents the outcome of the VAMOS design phas...

  5. XMM Future Operational Ground Segment

    Finn, T.; Kirsch, M.; Schmidt, F.; Pfeil, N.; Vasconcellos, A.; Martin, J.

    2014-07-01

    XMM-Newton has been operating for 14 years which have been characterised by an extraordinary scientific return leading to it being considered as one of the most important scientific missions operated by ESA. XMM-Newton has outlived its original operating lifetime and this has led to a new array of technical challenges which new software and operating strategies have greatly mitigated and have enabled XMM-Newton to continue to perform optimally. XMM-Newton relies on reaction wheels and thrusters to manoeuvre consuming on -board fuel and limiting XMM-Newtons operating life. As a result a new operating concept for the reaction wheels has been devised and reduces the fuel consumption by approximately 50% potentially allowing XMM-Newton to operate until 2028. This extension leads to a new set of challenges; firstly, a change in the orbital inclination causes XMM-Newtons ground station Kourou to develop a gap in coverage around perigee for a period of 5 years from mid-2014 and secondly, XMM-Newtons second prime ground station, Perth, is to be decommissioned at the end of 2015 due to regulation governing civil spectrum usage. This paper illustrates how these issues are resoled from a ground segment perspective and when implemented will ensure XMM-Newtons continuance into the next decade.

  6. Reproduction and application of human bouncing and jumping forces from visual marker data

    Racic, V.; Brownjohn, J. M. W.; Pavic, A.

    2010-08-01

    State-of-the-art facilities for measuring bouncing and jumping ground reaction forces (GRFs) comprise typically equipment for direct force measurement, i.e. single or multiple floor-mounted force plates. Artificial laboratory conditions and constraints imposed by the direct measurement systems, such as the small measuring area of a force plate, can have a strong influence on human ability to bounce and jump, naturally yielding unrepresentative force data. However, when dealing with issues like vibration serviceability assessment of real full-scale structures, such as floors, footbridges, staircases and grandstands, there is a growing need to estimate realistic GRFs under a wide range of natural conditions. This paper presents a novel method in the civil engineering context utilising 'free-field' measurement of human bouncing and jumping forces recorded continuously in time using motion capture technology transferred and adapted from biomechanical research. Results show that this kind of data can be used successfully in studies of human-structure dynamic interaction, specifically negative cue effect of a perceptibly vibrating structure on GRFs, energy flow and power in the human-structure system, and also synchronisation between individuals when bouncing/jumping in groups on more or less perceptibly moving structures.

  7. [The effect of the motion of forefoot joint at the force exerted upon the floor during walking exercise].

    Maeda, A; Nishizono, H; Ebashi, H; Shibayama, H

    1993-11-01

    In walking exercise the human body is exposed to external forces. Some of them are produced by constraints such as surface, shoes or opponent. In kick action of walking, the ground reaction force (GRF) is the most important external force. The magnitude of the GRF, its direction, and point of application have an influence on the load on the human body. The purpose of this study is to clarify the role of forefoot joint (artt. metatarsophalangeae) at the force exerted upon the floor during kick action of walking. The device used in this study to analyze the GRF and its three components consists of Kistler's force platform. Output from force transducer was collected online with a TEAC data recorder and MEM-4101 minicomputer. The impact force measurements were taken from the anterior-posterior force time curves at the take-off for 1 subject walking 10 trials at 2 m/sec with 2 different pairs of shoes (Shoes 1: thin sole of 4mm, and Shoes 2: thick sole of 40mm) and without shoes. High speed (200f/sec) cinematography was also used to analyze the angular displacement of forefoot joint at the take-off of walking exercise. The force acting at the forefoot joint may produce the anterior-posterior force of the GRF which is defined as the propelling power acting on the human body during walking exercise. The result showed that the impact force peak occurred 40-60 msec before take-off and the propelling part of kick action accounted for only about 6% of the external force.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8123187

  8. Prediction and mitigation analysis of ground vibration caused by running high-speed trains on rigid-frame viaducts

    Sun, Liangming; Xie, Weiping; He, Xingwen; Hayashikawa, Toshiro

    2016-03-01

    In this study a 3D numerical analysis approach is developed to predict the ground vibration around rigid-frame viaducts induced by running high-speed trains. The train-bridge-ground interaction system is divided into two subsystems: the train-bridge interaction and the soil-structure interaction. First, the analytical program to simulate bridge vibration with consideration of train-bridge interaction is developed to obtain the vibration reaction forces at the pier bottoms. The highspeed train is described by a multi-DOFs vibration system and the rigid-frame viaduct is modeled with 3D beam elements. Second, applying these vibration reaction forces as input external excitations, the ground vibration is simulated by using a general-purpose program that includes soil-structure interaction effects. The validity of the analytical procedure is confirmed by comparing analytical and experimental results. The characteristics of high-speed train-induced vibrations, including the location of predominant vibration, are clarified. Based on this information a proposed vibration countermeasure using steel strut and new barrier is found effective in reducing train-induced vibrations and it satisfies environmental vibration requirements. The vibration screening efficiency is evaluated by reduction VAL based on 1/3 octave band spectral analysis.

  9. Nuclear Reactions

    Bertulani, C. A.

    2009-01-01

    Nuclear reactions generate energy in nuclear reactors, in stars, and are responsible for the existence of all elements heavier than hydrogen in the universe. Nuclear reactions denote reactions between nuclei, and between nuclei and other fundamental particles, such as electrons and photons. A short description of the conservation laws and the definition of basic physical quantities is presented, followed by a more detailed account of specific cases: (a) formation and decay of compound nuclei;...

  10. The ground based plan

    The paper presents a report of ''The Ground Based Plan'' of the United Kingdom Science and Engineering Research Council. The ground based plan is a plan for research in astronomy and planetary science by ground based techniques. The contents of the report contains a description of:- the scientific objectives and technical requirements (the basis for the Plan), the present organisation and funding for the ground based programme, the Plan, the main scientific features and the further objectives of the Plan. (U.K.)

  11. Communication, concepts and grounding

    Velde, van der F.

    2015-01-01

    This article discusses the relation between communication and conceptual grounding. In the brain, neurons, circuits and brain areas are involved in the representation of a concept, grounding it in perception and action. In terms of grounding we can distinguish between communication within the brain

  12. Grounds Maintenance Evaluation.

    Chesapeake Public Schools, VA. Office of Program Evaluation.

    The Grounds Shop of the Chesapeake Public School Division (Virginia) Department of School Plants was evaluated in 1995-96. The goals of the grounds maintenance program are to provide safe and attractive grounds for students, parents, and staff of the school district. The evaluation examined the extent to which these goals are being met by using…

  13. Constructivist Grounded Theory?

    Barney G. Glaser, PhD, Hon. PhD

    2012-06-01

    Full Text Available AbstractI refer to and use as scholarly inspiration Charmaz’s excellent article on constructivist grounded theory as a tool of getting to the fundamental issues on why grounded theory is not constructivist. I show that constructivist data, if it exists at all, is a very, very small part of the data that grounded theory uses.

  14. Calculation of excitation functions of the 54,56,57,58Fe(, ) reaction from threshold to 30 MeV

    Damewan Suchiang; J Joseph Jeremiah; B M Jyrwa

    2014-10-01

    The cross-sections for the formation of 54,56,57,58Co in the 54,56,57,58Fe(, ) reaction from threshold to 30 MeV protons have been theoretically calculated using the TALYS-1.4 nuclear model code, whereby we have studied major nuclear reaction mechanisms, including direct, preequilibrium and compound nuclear reaction. Subsequently, the level density and shell damping parameters have been adjusted and at the same time, the odd–even effects are well comprehended. The excitation functions have been compared with experimental nuclear data. It is observed that the theoretical cross-sections match fairly well. Proton-induced reaction cross-sections provide clues to understand the nuclear structure and offers a good testing ground for ideas about nuclear forces. In addition, complete information in this field is very much required for application in accelerator-driven subcritical system.

  15. Theoretical studies of the chemiluminescence reactions; luminol

    Martínez Muñoz, Daniel

    2015-01-01

    The vast majority of chemical reactions occurs only in the ground state, however photochemical reactions like chemiluminescence take place in ground and excited states. In almost all chemiluminescence processes oxygen-oxygen bond breakage is involved. But, there is no general reason to explain why these processes occur via an oxygen-oxygen cleavage. These types of phenomena are usually highly exothermic. Computational chemistry has risen as a powerful tool to characterize and analyze chemical...

  16. Casimir-Polder forces on moving atoms

    Polarizable atoms and molecules experience the Casimir-Polder force near magnetoelectric bodies, a force that is induced by quantum fluctuations of the electromagnetic field and the matter. Atoms and molecules in relative motion to a magnetoelectric surface experience an additional velocity-dependent force. We present a full quantum-mechanical treatment of this force and identify a generalized Doppler effect, the time delay between photon emission and reabsorption, and the Roentgen interaction as its three sources. For ground-state atoms, the force is very small and always decelerating, hence commonly known as quantum friction. For atoms and molecules in electronically excited states, on the contrary, both decelerating and accelerating forces can occur depending on the magnitude of the atomic transition frequency relative to the surface-plasmon frequency.

  17. Towards Density Functional Calculations from Nuclear Forces

    Schwenk, A; Polonyi, J.

    2004-01-01

    We propose a method for microscopic calculations of nuclear ground-state properties in the framework of density functional theory. We discuss how the density functional is equivalent to the effective action for the density, thereby establishing a constructive framework for density functional calculations from nuclear forces. The presented approach starts from non-interacting nucleons in a background potential (a simple approximation for the mean field). The nuclear forces are then gradually t...

  18. Nanomechanical sensing of gravitational wave-induced Casimir force perturbations

    Pinto, Fabrizio

    2014-06-01

    It is shown by means of the optical medium analogy that the static Casimir force between two conducting plates is modulated by gravitational waves. The magnitude of the resulting force changes within the range of already existing small force metrology. It is suggested to enhance the effects on a Casimir force oscillator by mechanical parametric amplification driven by periodic illumination of interacting semiconducting boundaries. This represents a novel opportunity for the ground-based laboratory detection of gravitational waves on the nanoscale.

  19. Net Gains from Conjunctive Use of Surface and Ground Water

    Waqar A. Jehangir; Hugh Turral; Shahbaz Khan

    2003-01-01

    Pakistan is fortunate enough because its soils, topography and climate are generally suitable for farming but its agriculture sector faces the problem of scarcity of the irrigation water. This paucity of irrigation supplies has forced the farmers to use the ground water to augment their surface supplies. The quality of ground water in Pakistan varies from fit for irrigation to moderately saline to sodic. Thus the tubewell owners in the marginal quality ground water areas are bound to use the ...

  20. Inflight Performance of Cassini Reaction Wheel Bearing Drag in 1997-2013

    Lee, Allan Y.; Wang, Eric K.

    2013-01-01

    As the first spacecraft to achieve orbit at Saturn in 2004, Cassini has collected science data throughout its four-year prime mission (2004-08), and has since been approved for a first and second extended missions through September 2017. Cassini is a three-axis stabilized spacecraft. It uses reaction wheels to achieve high level of spacecraft pointing stability that is needed during imaging operations of several science instruments. The Cassini flight software makes in-flight estimates of reaction wheel bearing drag torque and made them available to the mission operations team. These telemetry data are being trended for the purpose of monitoring the long-term health of the reaction wheel bearings. Anomalous drag torque signatures observed over the past 15 years are described in this paper. One of these anomalous drag conditions is bearing cage instability that appeared (and disappeared) spontaneously and unpredictably. Cage instability is an uncontrolled vibratory motion of the bearing cage that can produce high-impact forces internal to the bearing that will cause intermittent and erratic torque transients. Characteristics of the observed cage instabilities and other drag torque "spikes" are described in this paper. In day-to-day operations, the reaction wheels' rates must be neither too high nor too low. To protect against operating the wheels in any undesirable conditions (such as prolonged low spin rate operations), a ground software tool named Reaction Wheel Bias Optimization Tool (RBOT) was developed for the management of the wheels. Disciplined and long-term use of this ground software has led to significant reduction in the daily consumption rate of the wheels' low spin rate dwell time. Flight experience on the use of this ground software tool as well as other lessons learned on the management of Cassini reaction wheels is given in this paper.

  1. Modernization of the Cassini Ground System

    Razo, Gus; Fujii, Tammy J.

    2014-01-01

    The Cassini Spacecraft and its ground system have been operational for over 16 years. Modernization presents several challenges due to the personnel, processes, and tools already invested and embedded into the current ground system structure. Every mission's ground system has its own unique complexities and challenges, involving various organizational units. As any mission from its inception to its execution, schedules are always tight. This forces GDS engineers to implement a working ground system that is not necessarily fully optimized. Ground system challenges increase as technology evolves and cyber threats become more sophisticated. Cassini's main challenges were due to its ground system existing before many security requirements were levied on the multi-mission tools and networks. This caused a domino effect on Cassini GDS tools that relied on outdated technological features. In the aerospace industry reliable and established technology is preferred over innovative yet less proven technology. Loss of data for a spacecraft mission can be catastrophic; therefore, there is a reluctance to make changes and updates to the ground system. Nevertheless, all missions and associated teams face the need to modernize their processes and tools. Systems development methods from well-known system analysis and design principles can be applied to many missions' ground systems. Modernization should always be considered, but should be done in such a way that it does not affect flexibility nor interfere with established practices. Cassini has accomplished a secure and efficient ground data system through periodic updates. The obstacles faced while performing the modernization of the Cassini ground system will be outlined, as well as the advantages and challenges that were encountered.

  2. DESTRUCTION CONDITIONS WHEN DITTING HOMOGENEOUS GROUND AND GROUND WITH INCLUSION

    Nichke, V.; Demishkan, V.

    2005-01-01

    On the base of analyses strained state the strong a ground with inclusion, and take into account a bigger traction effort of a modern bulldozers, was shoved as destroyed a rocks ground, a ground with inclusion, homogeneous a ground.

  3. Effects of stride frequency and foot position at landing on braking force, hip torque, impact peak force and the metabolic cost of running in humans.

    Lieberman, Daniel E; Warrener, Anna G; Wang, Justin; Castillo, Eric R

    2015-11-01

    Endurance runners are often advised to use 90 strides min(-1), but how optimal is this stride frequency and why? Endurance runners are also often advised to maintain short strides and avoid landing with the feet too far in front of their hips or knees (colloquially termed 'overstriding'), but how do different kinematic strategies for varying stride length at the same stride frequency affect economy and impact peaks? Linear mixed models were used to analyze repeated measures of stride frequency, the anteroposterior position of the foot at landing, V̇O2 , lower extremity kinematics and vertical ground reaction forces in 14 runners who varied substantially in height and body mass and who were asked to run at 75, 80, 85, 90 and 95 strides min(-1) at 3.0 m s(-1). For every increase of 5 strides min(-1), maximum hip flexor moments in the sagittal plane increased by 5.8% (Prates of loading (P=0.07) of the vertical ground reaction force impact peak. Finally, the mean metabolically optimal stride frequency was 84.8±3.6 strides min(-1), with 50.4% of the variance explained by the trade-off between minimizing braking forces versus maximum hip flexor moments during swing. The results suggest that runners may benefit from a stride frequency of approximately 85 strides min(-1) and by landing at the end of swing phase with a relatively vertical tibia. PMID:26538175

  4. Reaction Wheel Disturbance Model Extraction Software Project

    National Aeronautics and Space Administration — Reaction wheel mechanical noise is one of the largest sources of disturbance forcing on space-based observatories. Such noise arises from mass imbalance, bearing...

  5. Dispersive forces on bodies and atoms: a unified approach

    Raabe, Christian; Welsch, Dirk-Gunnar

    2006-01-01

    A unified approach to the calculation of dispersive forces on ground-state bodies and atoms is given. It is based on the ground-state Lorentz force density acting on the charge and current densities attributed to the polarization and magnetization in linearly, locally, and causally responding media. The theory is applied to dielectric macro- and micro-objects, including single atoms. Existing formulas valid for weakly polarizable matter are generalized to allow also for strongly polarizable m...

  6. The swim force as a body force

    Yan, Wen; Brady, John

    2015-11-01

    Net (as opposed to random) motion of active matter results from an average swim (or propulsive) force. It is shown that the average swim force acts like a body force - an internal body force [Yan and Brady, Soft Matter, DOI:10.1039/C5SM01318F]. As a result, the particle-pressure exerted on a container wall is the sum of the swim pressure [Takatori et al., Phys. Rev. Lett., 2014, 113, 028103] and the `weight' of the active particles. A continuum mechanical description is possible when variations occur on scales larger than the run length of the active particles and gives a Boltzmann-like distribution from a balance of the swim force and the swim pressure. Active particles may also display `action at a distance' and accumulate adjacent to (or be depleted from) a boundary without any external forces. In the momentum balance for the suspension - the mixture of active particles plus fluid - only external body forces appear.

  7. Malaysia and forced migration

    Arzura Idris

    2012-01-01

    This paper analyzes the phenomenon of “forced migration” in Malaysia. It examines the nature of forced migration, the challenges faced by Malaysia, the policy responses and their impact on the country and upon the forced migrants. It considers forced migration as an event hosting multifaceted issues related and relevant to forced migrants and suggests that Malaysia has been preoccupied with the issue of forced migration movements. This is largely seen in various responses invoked from Malaysi...

  8. Handbook of force transducers

    Stefanescu, Dan Mihai

    2011-01-01

    Part I introduces the basic ""Principles and Methods of Force Measurement"" acording to a classification into a dozen of force transducers types: resistive, inductive, capacitive, piezoelectric, electromagnetic, electrodynamic, magnetoelastic, galvanomagnetic (Hall-effect), vibrating wires, (micro)resonators, acoustic and gyroscopic. Two special chapters refer to force balance techniques and to combined methods in force measurement. Part II discusses the ""(Strain Gauge) Force Transducers Components"", evolving from the classical force transducer to the digital / intelligent one, with the inco

  9. Electronic transitions and intermolecular forces

    This thesis describes two different subjects - electronic transitions and intermolecular forces - that are related mainly by the following observation: The wavenumber at which an electronic transition in an atom or molecule occurs, depends on the environment of that atom or molecule. This implies, for instance, that when a molecule becomes solvated its absorption spectrum may be shifted either to the blue or to the red side of the original gasphase spectrum. In part I attention is paid to the experimental aspects of VUV spectroscopy, both in the gasphase and in the condensed phase. In part II a series of papers are presented, dealing with the calculation of intermolecular forces (and some related topics) both for the ground state and for the excited state interactions, using different non-empirical methods. The calculations provide, among other results, a semiquantitative interpretation of the spectral blue shifts encountered in our experiments. (Auth.)

  10. Piezonuclear Reactions

    Cardone, Fabio; Petrucci, Andrea

    2010-01-01

    In this paper, we deal with the subject of piezonuclear reactions, namely nuclear reactions (of new type) triggered by pressure waves. We discuss the experimental evidences obtained in the last two decades, which can be summarized essentially as follows: experiments in cavitation of liquids, where transmutation of elements, creation of elements and emission of neutrons have been observed; emission of neutrons in brittle failure of solids subjected to mechanical pressure; alteration of the lifetime of un unstable element (thorium) subjected to cavitation. A theoretical model to explain these facts is proposed. Future perspectives of these experimental and theoretical investigations are also underlined.

  11. Reaction mechanisms

    The 1988 progress report of the Reaction Mechanisms laboratory (Polytechnic School, France), is presented. The research topics are: the valence bond methods, the radical chemistry, the modelling of the transition states by applying geometric constraints, the long range interactions (ion - molecule) in gaseous phase, the reaction sites in gaseous phase and the mass spectroscopy applications. The points of convergence between the investigations of the mass spectroscopy and the theoretical chemistry teams, as well as the purposes guiding the research programs, are discussed. The published papers, the conferences, the congress communications and the thesis, are also reported

  12. Neutrino nuclear response and photo nuclear reaction

    Ejiri, H.; Titov, A. I.; .Boswell, M; Young, A.

    2013-01-01

    Photo nuclear reactions are shown to be used for studying neutrino/weak nuclear responses involved in astro-neutrino nuclear interactions and double beta decays. Charged current weak responses for ground and excited states are studied by using photo nuclear reactions through isobaric analog states of those states, while neutral current weak responses for excited states are studied by using photo nuclear reactions through the excited states. The weak interaction strengths are studied by measur...

  13. Salmon Muscle Adherence to Polymer Coatings and Determination of Antibiotic Residues by Reversed-Phase High-Performance Liquid Chromatography Coupled to Selected Reaction Monitoring Mass Spectrometry, Atomic Force Microscopy, and Fourier Transform Infrared Spectroscopy

    E. Zumelzu

    2015-01-01

    Full Text Available The persistent adhesion of salmon muscle to food container walls after treatment with urea solution was observed. This work evaluated the diffusion of antibiotics from the salmon muscle to the polyethylene terephthalate (PET coating protecting the electrolytic chromium coated steel (ECCS plates. New aquaculture production systems employ antibiotics such as florfenicol, florfenicol amine, oxytetracycline, and erythromycin to control diseases. The introduction of antibiotics is a matter of concern regarding the effects on human health and biodiversity. It is important to determine their impact on the adhesion of postmortem salmon muscle to can walls and the surface and structural changes affecting the functionality of multilayers. This work characterized the changes occurring in the multilayer PET polymer and steel of containers by electron microscopy, 3D atomic force microscopy (3D-AFM, X-ray photoelectron spectroscopy (XPS, and Fourier transform infrared spectroscopy (FT-IR analyses. A robust mass spectrometry methodology was employed to determine the presence of antibiotic residues. No evidence of antibiotics was observed on the protective coating in the range between 0.001 and 2.0 ng/mL; however, the presence of proteins, cholesterol, and alpha-carotene was detected. This in-depth profiling of the matrix-level elements is relevant for the use of adequate materials in the canning export industry.

  14. Energy shift and Casimir-Polder force for an atom out of thermal equilibrium near a dielectric substrate

    Zhou, Wenting; Yu, Hongwei

    2014-09-01

    We study the energy shift and the Casimir-Polder force of an atom out of thermal equilibrium near the surface of a dielectric substrate. We first generalize, adopting the local source hypothesis, the formalism proposed by Dalibard, Dupont-Roc, and Cohen-Tannoudji [J. Phys. (Paris) 43, 1617 (1982), 10.1051/jphys:0198200430110161700; J. Phys. (Paris) 45, 637 (1984), 10.1051/jphys:01984004504063700], which separates the contributions of thermal fluctuations and radiation reaction to the energy shift and allows a distinct treatment of atoms in the ground and excited states, to the case out of thermal equilibrium, and then we use the generalized formalism to calculate the energy shift and the Casimir-Polder force of an isotropically polarizable neutral atom. We identify the effects of the thermal fluctuations that originate from the substrate and the environment and discuss in detail how the Casimir-Polder force out of thermal equilibrium behaves in three different distance regions in both the low-temperature limit and the high-temperature limit for both the ground-state and excited-state atoms, with special attention devoted to the distinctive features as opposed to thermal equilibrium. In particular, we recover the distinctive behavior of the atom-wall force out of thermal equilibrium at large distances in the low-temperature limit recently found in a different theoretical framework, and furthermore we give a concrete region where this behavior holds.

  15. Pesticides in Ground Water

    Bjerg, Poul Løgstrup

    1996-01-01

    Review af: Jack E. Barbash & Elizabeth A. Resek (1996). Pesticides in Ground Water. Distribution trends and governing factors. Ann Arbor Press, Inc. Chelsea, Michigan. pp 588.......Review af: Jack E. Barbash & Elizabeth A. Resek (1996). Pesticides in Ground Water. Distribution trends and governing factors. Ann Arbor Press, Inc. Chelsea, Michigan. pp 588....

  16. Thermal Casimir versus Casimir-Polder Forces: Equilibrium and Nonequilibrium Forces

    We critically discuss whether and under what conditions Lifshitz theory may be used to describe thermal Casimir-Polder forces on atoms or molecules. An exact treatment of the atom-field coupling reveals that for a ground-state atom (molecule), terms associated with virtual-photon absorption lead to a deviation from the traditional Lifshitz result; they are identified as a signature of nonequilibrium dynamics. Even the equilibrium force on a thermalized atom (molecule) may be overestimated when using the ground-state polarizability instead of its thermal counterpart

  17. Modulating tibiofemoral contact force in the sheep hind limb via treadmill walking: Predictions from an opensim musculoskeletal model.

    Lerner, Zachary F; Gadomski, Benjamin C; Ipson, Allison K; Haussler, Kevin K; Puttlitz, Christian M; Browning, Raymond C

    2015-08-01

    Sheep are a predominant animal model used to study a variety of orthopedic conditions. Understanding and controlling the in-vivo loading environment in the sheep hind limb is often necessary for investigations relating to bone and joint mechanics. The purpose of this study was to develop a musculoskeletal model of an adult sheep hind limb and investigate the effects of treadmill walking speed on muscle and joint contact forces. We constructed the skeletal geometry of the model from computed topography images. Dual-energy x-ray absorptiometry was utilized to establish the inertial properties of each model segment. Detailed dissection and tendon excursion experiments established the requisite muscle lines of actions. We used OpenSim and experimentally-collected marker trajectories and ground reaction forces to quantify muscle and joint contact forces during treadmill walking at 0.25 m• s(-1) and 0.75 m• s(-1) . Peak compressive and anterior-posterior tibiofemoral contact forces were 20% (0.38 BW, p = 0.008) and 37% (0.17 BW, p = 0.040) larger, respectively, at the moderate gait speed relative to the slower speed. Medial-lateral tibiofemoral contact forces were not significantly different. Adjusting treadmill speed appears to be a viable method to modulate compressive and anterior-posterior tibiofemoral contact forces in the sheep hind limb. The musculoskeletal model is freely-available at www.SimTK.org. PMID:25721318

  18. Loaded Vertical Jumping: Force-Velocity Relationship, Work, and Power.

    Feeney, Daniel; Stanhope, Steven J; Kaminski, Thomas W; Machi, Anthony; Jaric, Slobodan

    2016-04-01

    The aims of the current study were to explore the pattern of the force-velocity (F-V) relationship of leg muscles, evaluate the reliability and concurrent validity of the obtained parameters, and explore the load associated changes in the muscle work and power output. Subjects performed maximum vertical countermovement jumps with a vest ranging 0-40% of their body mass. The ground reaction force and leg joint kinematics and kinetics were recorded. The data revealed a strong and approximately linear F-V relationship (individual correlation coefficients ranged from 0.78-0.93). The relationship slopes, F- and V-intercepts, and the calculated power were moderately to highly reliable (0.67 power with respect to the directly measured values, was (on average) moderate. Despite that a load increase was associated with a decrease in both the countermovement depth and absolute power, the absolute work done increased, as well as the relative contribution of the knee work. The obtained findings generally suggest that the loaded vertical jumps could not only be developed into a routine method for testing the capacities of leg muscles, but also reveal the mechanisms of adaptation of multijoint movements to different loading conditions. PMID:26398963

  19. Ground energy coupling

    Metz, P. D.

    The feasibility of ground coupling for various heat pump systems was investigated. Analytical heat flow models were developed to approximate design ground coupling devices for use in solar heat pump space conditioning systems. A digital computer program called GROCS (GRound Coupled Systems) was written to model 3-dimensional underground heat flow in order to simulate the behavior of ground coupling experiments and to provide performance predictions which have been compared to experimental results. GROCS also has been integrated with TRNSYS. Soil thermal property and ground coupling device experiments are described. Buried tanks, serpentine earth coils in various configurations, lengths and depths, and sealed vertical wells are being investigated. An earth coil used to heat a house without use of resistance heating is described.

  20. Stochastic ground motion simulation

    Rezaeian, Sanaz; Xiaodan, Sun

    2014-01-01

    Strong earthquake ground motion records are fundamental in engineering applications. Ground motion time series are used in response-history dynamic analysis of structural or geotechnical systems. In such analysis, the validity of predicted responses depends on the validity of the input excitations. Ground motion records are also used to develop ground motion prediction equations(GMPEs) for intensity measures such as spectral accelerations that are used in response-spectrum dynamic analysis. Despite the thousands of available strong ground motion records, there remains a shortage of records for large-magnitude earthquakes at short distances or in specific regions, as well as records that sample specific combinations of source, path, and site characteristics.

  1. Ground Metric Learning

    Cuturi, Marco

    2011-01-01

    Transportation distances have been used for more than a decade now in machine learning to compare histograms of features. They have one parameter: the ground metric, which can be any metric between the features themselves. As is the case for all parameterized distances, transportation distances can only prove useful in practice when this parameter is carefully chosen. To date, the only option available to practitioners to set the ground metric parameter was to rely on a priori knowledge of the features, which limited considerably the scope of application of transportation distances. We propose to lift this limitation and consider instead algorithms that can learn the ground metric using only a training set of labeled histograms. We call this approach ground metric learning. We formulate the problem of learning the ground metric as the minimization of the difference of two polyhedral convex functions over a convex set of distance matrices. We follow the presentation of our algorithms with promising experimenta...

  2. Performing Isometric Force Control in Combination with a Cognitive Task: A Multidimensional Assessment

    Jean-Jacques Temprado; Solveig Vieluf; Nicolas Bricot; Eric Berton; Rita Sleimen-Malkoun

    2015-01-01

    Introduction We used a multidimensional approach to study isometric force control in single and dual-task conditions. Methods Multiple measures of performance, efficiency, variability, and structural interference were calculated at low and higher force levels under single (force maintenance) and dual-task (force maintenance and reaction time) conditions. Results Reaction time and signal-to-noise ratio were larger in the dual-task conditions. They were also greater for the higher force conditi...

  3. Modifying landing mat material properties may decrease peak contact forces but increase forefoot forces in gymnastics landings.

    Mills, Chris; Yeadon, Maurice R; Pain, Matthew T G

    2010-09-01

    This study investigated how changes in the material properties of a landing mat could minimise ground reaction forces (GRF) and internal loading on a gymnast during landing. A multi-layer model of a gymnastics competition landing mat and a subject-specific seven-link wobbling mass model of a gymnast were developed to address this aim. Landing mat properties (stiffness and damping) were optimised using a Simplex algorithm to minimise GRF and internal loading. The optimisation of the landing mat parameters was characterised by minimal changes to the mat's stiffness (<0.5%) but increased damping (272%) compared to the competition landing mat. Changes to the landing mat resulted in reduced peak vertical and horizontal GRF and reduced bone bending moments in the shank and thigh compared to a matching simulation. Peak bone bending moments within the thigh and shank were reduced by 6% from 321.5 Nm to 302.5Nm and GRF by 12% from 8626 N to 7552 N when compared to a matching simulation. The reduction in these forces may help to reduce the risk of bone fracture injury associated with a single landing and reduce the risk of a chronic injury such as a stress fracture. PMID:21162361

  4. Convection in Drying and Freezing Ground

    Faizal, Mir

    2012-01-01

    In this paper we analyse the drying of a soil composed of particles, water and solute impurities, and study the occurrence of convective instabilities during evaporation. We find that the main driving force for instability is the formation of a concentration gradient at the soil surface due to the evaporation of water. A similar phenomenon may occur during the thawing of frozen ground in Arctic regions.

  5. Relational grounding facilitates development of scientifically useful multiscale models

    Lam Tai

    2011-09-01

    Full Text Available Abstract We review grounding issues that influence the scientific usefulness of any biomedical multiscale model (MSM. Groundings are the collection of units, dimensions, and/or objects to which a variable or model constituent refers. To date, models that primarily use continuous mathematics rely heavily on absolute grounding, whereas those that primarily use discrete software paradigms (e.g., object-oriented, agent-based, actor typically employ relational grounding. We review grounding issues and identify strategies to address them. We maintain that grounding issues should be addressed at the start of any MSM project and should be reevaluated throughout the model development process. We make the following points. Grounding decisions influence model flexibility, adaptability, and thus reusability. Grounding choices should be influenced by measures, uncertainty, system information, and the nature of available validation data. Absolute grounding complicates the process of combining models to form larger models unless all are grounded absolutely. Relational grounding facilitates referent knowledge embodiment within computational mechanisms but requires separate model-to-referent mappings. Absolute grounding can simplify integration by forcing common units and, hence, a common integration target, but context change may require model reengineering. Relational grounding enables synthesis of large, composite (multi-module models that can be robust to context changes. Because biological components have varying degrees of autonomy, corresponding components in MSMs need to do the same. Relational grounding facilitates achieving such autonomy. Biomimetic analogues designed to facilitate translational research and development must have long lifecycles. Exploring mechanisms of normal-to-disease transition requires model components that are grounded relationally. Multi-paradigm modeling requires both hyperspatial and relational grounding.

  6. Simple Assessment of Post-Grounding Loads and Strength of Ships

    Paik, Jeom Kee; Pedersen, Preben Terndrup

    1997-01-01

    The aim of the present study is to determine the sectional forces induced by the ship grounding and also to assess the residual strength of grounded ship hulls. An analytical approach is used to estimate the grounding- induced sectional forces of ships. The extent and location of structural damage...... due to grounding is defined based on the ABS Safe Hull guide. The residual strength of damaged hulls is calculated by using a simple analytical formula. The method is applied to the residual strength assessment of a double-hull tanker of 38.400 dwt damaged due to grounding....

  7. Grounded running in quails: simulations indicate benefits of observed fixed aperture angle between legs before touch-down.

    Andrada, Emanuel; Rode, Christian; Blickhan, Reinhard

    2013-10-21

    Many birds use grounded running (running without aerial phases) in a wide range of speeds. Contrary to walking and running, numerical investigations of this gait based on the BSLIP (bipedal spring loaded inverted pendulum) template are rare. To obtain template related parameters of quails (e.g. leg stiffness) we used x-ray cinematography combined with ground reaction force measurements of quail grounded running. Interestingly, with speed the quails did not adjust the swing leg's angle of attack with respect to the ground but adapted the angle between legs (which we termed aperture angle), and fixed it about 30ms before touchdown. In simulations with the BSLIP we compared this swing leg alignment policy with the fixed angle of attack with respect to the ground typically used in the literature. We found symmetric periodic grounded running in a simply connected subset comprising one third of the investigated parameter space. The fixed aperture angle strategy revealed improved local stability and surprising tolerance with respect to large perturbations. Starting with the periodic solutions, after step-down step-up or step-up step-down perturbations of 10% leg rest length, in the vast majority of cases the bipedal SLIP could accomplish at least 50 steps to fall. The fixed angle of attack strategy was not feasible. We propose that, in small animals in particular, grounded running may be a common gait that allows highly compliant systems to exploit energy storage without the necessity of quick changes in the locomotor program when facing perturbations. PMID:23831138

  8. Force Measurement on the GLAST Delta II Flight

    Gordon, Scott; Kaufman, Daniel

    2009-01-01

    This viewgraph presentation reviews the interface force measurement at spacecraft separation of GLAST Delta II. The contents include: 1) Flight Force Measurement (FFM) Background; 2) Team Members; 3) GLAST Mission Overview; 4) Methodology Development; 5) Ground Test Validation; 6) Flight Data; 7) Coupled Loads Simulation (VCLA & Reconstruction); 8) Basedrive Simulation; 9) Findings; and 10) Summary and Conclusions.

  9. Snowboard Jumping, Newton's Second Law and the Force on Landing

    O'Shea, Michael J.

    2004-01-01

    An application of Newton's second law to a snowboarder dropping off a vertical ledge shows that the average normal force during landing (force exerted by the ground on the snowboarder) is determined by four factors. It is shown that the flexing of the legs, the softness of the snow, the angle of the landing surface and the forward motion of the…

  10. Surface and Interfacial Forces

    Butt, Hans-Jurgen

    2010-01-01

    This systematic introduction to the topic includes theoretical concepts to help readers understand and predict surface forces, while also integrating experimental techniques and practical applications with up-to-date examples plus motivating exercises. Starting with intermolecular forces, the authors discuss different surfaces forces, with a major part devoted to surface forces between solid surfaces in liquid media. In addition, they cover surface forces between liquid-vapor interfaces and between liquid-liquid interfaces.

  11. Airport Ground Staff Scheduling

    Clausen, Tommy

    Modern airports are centers of transportation that service a large number of aircraft and passengers every day. To facilitate this large volume of transportation, airports are subject to many logistical and decision problems that must continuously be solved to make sure each flight and passenger...... ownership. As airports are in competition to attract airline routes, efficient and reliable ground handling operations are imperative for the viability and continued growth of both airports and airlines. The increasing liberalization of the ground handling market prompts ground handling operators to...... planning, to highly detailed scheduling problems arising in the highly dynamic environment of airports....

  12. Ground Source Heat Pumps

    Lale Valizade

    2013-01-01

    A heat pump is a device that is able to transfer heat from one fluid at a lower temperature to another at a higher temperature. Ground source heat pumps are generally classified by the type of ground loop. The coefficient of performance (COP) is used to define the heating performance of heat pumps. Both the COP and EER values are valid only at the specific test conditions used in the rating. A ground source pump could reach 450%, compared with an efficient gas boiler of 90% obviously this is ...

  13. Dynamics of thermal Casimir-Polder forces on polar molecules

    We study the influence of thermal Casimir-Polder forces on the near-surface trapping of cold polar molecules, with emphasis on LiH and YbF near a Au surface at room temperature. We show that even for a molecule initially prepared in its electronic and rovibrational ground state, the Casimir-Polder force oscillates with the molecule-wall separation. The nonresonant force and the evanescent part of the resonant force almost exactly cancel at high temperature which results in a saturation of the (attractive) force in this limit. This implies that the Casimir-Polder force on a fully thermalized molecule can differ dramatically from that obtained using a naive perturbative expansion of the Lifshitz formula based on the molecular ground-state polarizability. A dynamical calculation reveals how the spatial oscillations die out on a typical time scale of several seconds as thermalization of the molecule with its environment sets in.

  14. Force modeling for incisions into various tissues with MRF haptic master

    Kim, Pyunghwa; Kim, Soomin; Park, Young-Dai; Choi, Seung-Bok

    2016-03-01

    This study proposes a new model to predict the reaction force that occurs in incisions during robot-assisted minimally invasive surgery. The reaction force is fed back to the manipulator by a magneto-rheological fluid (MRF) haptic master, which is featured by a bi-directional clutch actuator. The reaction force feedback provides similar sensations to laparotomy that cannot be provided by a conventional master for surgery. This advantage shortens the training period for robot-assisted minimally invasive surgery and can improve the accuracy of operations. The reaction force modeling of incisions can be utilized in a surgical simulator that provides a virtual reaction force. In this work, in order to model the reaction force during incisions, the energy aspect of the incision process is adopted and analyzed. Each mode of the incision process is classified by the tendency of the energy change, and modeled for realistic real-time application. The reaction force model uses actual reaction force information with three types of actual tissues: hard tissue, medium tissue, and soft tissue. This modeled force is realized by the MRF haptic master through an algorithm based on the position and velocity of a scalpel using two different control methods: an open-loop algorithm and a closed-loop algorithm. The reaction forces obtained from the proposed model are compared with a desired force in time domain.

  15. Variance associated with subject velocity and trial repetition during force platform gait analysis in a heterogeneous population of clinically normal dogs.

    Hans, Eric C; Zwarthoed, Berdien; Seliski, Joseph; Nemke, Brett; Muir, Peter

    2014-12-01

    Factors that contribute to variance in ground reaction forces (GRF) include dog morphology, velocity, and trial repetition. Narrow velocity ranges are recommended to minimize variance. In a heterogeneous population of clinically normal dogs, it was hypothesized that the dog subject effect would account for the majority of variance in peak vertical force (PVF) and vertical impulse (VI) at a trotting gait, and that narrow velocity ranges would be associated with less variance. Data from 20 normal dogs were obtained. Each dog was trotted across a force platform at its habitual velocity, with controlled acceleration (±0.5 m/s(2)). Variance effects from 12 trotting velocity ranges were examined using repeated-measures analysis-of-covariance. Significance was set at P trotting dogs. This concept is important for clinical trial design. PMID:25457264

  16. Decentralized Ground Staff Scheduling

    Sørensen, M. D.; Clausen, Jens

    2002-01-01

    Typically, ground staff scheduling is centrally planned for each terminal in an airport. The advantage of this is that the staff is efficiently utilized, but a disadvantage is that staff spends considerable time walking between stands. In this paper a decentralized approach for ground staff scheduling is investigated. The airport terminal is divided into zones, where each zone consists of a set of stands geographically next to each other. Staff is assigned to work in only one zone and the sta...

  17. Force of an actin spring

    Shin, Jennifer; Mahadevan, L.; Matsudaira, Paul

    2003-03-01

    The acrosomal process of the horseshoe crab sperm is a novel mechanochemical molecular spring that converts its elastic stain energy to mechanical work upon the chemical activation by Ca2+. Twisted and bent, the initial state of the acrosomal bundle features a high degree of complexity in its structure and the energy is believed to be stored in the highly strained actin filaments as an elastic potential energy. When activated, the bundle relaxes from the coil of the highly twisted and bent filaments to its straight conformation at a mean velocity of 15um/s. The mean extension velocity increases dramatically from 3um/s to 27um/s when temperature of the medium is changed from 9.6C to 32C (respective viscosities of 1.25-0.75cp), yet it exhibits a very weak dependence on changes in the medium viscosity (1cp-33cp). These experiments suggest that the uncoiling of the actin spring should be limited not by the viscosity of the medium but by the unlatching events of involved proteins at a molecular level. Unlike the viscosity-limited processes, where force is directly related to the rate of the reaction, a direct measurement is required to obtain the spring force of the acrosomal process. The extending acrosomal bundle is forced to push against a barrier and its elastic buckling response is analyzed to measure the force generated during the uncoiling.

  18. Surface plasmon polariton assisted optical pulling force

    Petrov, M I; Bogdanov, A A; Shalin, A S; Dogariu, A

    2016-01-01

    We demonstrate both analytically and numerically the existence of optical pulling forces acting on particles located near plasmonic interfaces. Two main factors contribute to the appearance of this negative reaction force. The interference between the incident and reflected waves induces a rotating dipole with an asymmetric scattering pattern while the directional excitation of surface plasmon polaritons (SPP) enhances the linear momentum of scattered light. The strongly asymmetric SPP excitation is determined by spin-orbit coupling of the rotating dipole and surface plasmon polariton. As a result of the total momentum conservation, the force acting on the particle points in a direction opposite to the incident wave propagation. We derive analytical expressions for the force acting on a dipolar particles placed in the proximity of plasmonic surfaces. Analytical expressions for this pulling force are derived within the dipole approximation and are in excellent agreement with results of electromagnetic numerica...

  19. Repulsive casimir forces

    We discuss repulsive Casimir forces between dielectric materials with nontrivial magnetic susceptibility. It is shown that considerations based on the naive pairwise summation of van der Waals and Casimir-Polder forces may not only give an incorrect estimate of the magnitude of the total Casimir force but even the wrong sign of the force when materials with high dielectric and magnetic responses are involved. Indeed repulsive Casimir forces may be found in a large range of parameters, and we suggest that the effect may be realized in known materials. The phenomenon of repulsive Casimir forces may be of importance both for experimental study and for nanomachinery applications

  20. Casimir-Polder forces, boundary conditions and fluctuations

    We review different aspects of atom-atom and atom-wall Casimir-Polder forces. We first discuss the role of a boundary condition on the interatomic Casimir-Polder potential between two ground-state atoms, and give a physically transparent interpretation of the results in terms of vacuum fluctuations and image atomic dipoles. We then discuss the known atom-wall Casimir-Polder force for ground- and excited-state atoms, using a different method which is also suited to extension to time-dependent situations. Finally, we consider the fluctuation of the Casimir-Polder force between a ground-state atom and a conducting wall, and discuss possible observation of this force fluctuation

  1. Casimir-Polder forces, boundary conditions and fluctuations

    Messina, Riccardo; Rizzuto, Lucia; Spagnolo, Salvatore; Vasile, Ruggero; 10.1088/1751-8113/41/16/164031

    2012-01-01

    We review different aspects of the atom-atom and atom-wall Casimir-Polder forces. We first discuss the role of a boundary condition on the interatomic Casimir-Polder potential between two ground-state atoms, and give a physically transparent interpretation of the results in terms of vacuum fluctuations and image atomic dipoles. We then discuss the known atom-wall Casimir-Polder force for ground- and excited-state atoms, using a different method which is also suited for extension to time-dependent situations. Finally, we consider the fluctuation of the Casimir-Polder force between a ground-state atom and a conducting wall, and discuss possible observation of this force fluctuation.

  2. Force propagation and force generation in cells.

    Jonas, Oliver; Duschl, Claus

    2010-09-01

    Determining how forces are produced by and propagated through the cytoskeleton (CSK) of the cell is of great interest as dynamic processes of the CSK are intimately correlated with many molecular signaling pathways. We are presenting a novel approach for integrating measurements on cell elasticity, transcellular force propagation, and cellular force generation to obtain a comprehensive description of dynamic and mechanical properties of the CSK under force loading. This approach uses a combination of scanning force microscopy (SFM) and Total Internal Reflection Fluorescence (TIRF) microscopy. We apply well-defined loading schemes onto the apical cell membrane of fibroblasts using the SFM and simultaneously use TIRF microscopy to image the topography of the basal cell membrane. The locally distinct changes of shape and depth of the cytoskeletal imprints onto the basal membrane are interpreted as results of force propagation through the cytoplasm. This observation provides evidence for the tensegrity model and demonstrates the usefulness of our approach that does not depend on potentially disturbing marker compounds. We confirm that the actin network greatly determines cell stiffness and represents the substrate that mediates force transduction through the cytoplasm of the cell. The latter is an essential feature of tensegrity. Most importantly, our new finding that, both intact actin and microtubule networks are required for enabling the cell to produce work, can only be understood within the framework of the tensegrity model. We also provide, for the first time, a direct measurement of the cell's mechanical power output under compression at two femtowatts. PMID:20607861

  3. Forces in general relativity

    Many textbooks dealing with general relativity do not demonstrate the derivation of forces in enough detail. The analyses presented herein demonstrate straightforward methods for computing forces by way of general relativity. Covariant divergence of the stress-energy-momentum tensor is used to derive a general expression of the force experienced by an observer in general coordinates. The general force is then applied to the local co-moving coordinate system of a uniformly accelerating observer, leading to an expression of the inertial force experienced by the observer. Next, applying the general force in Schwarzschild coordinates is shown to lead to familiar expressions of the gravitational force. As a more complex demonstration, the general force is applied to an observer in Boyer-Lindquist coordinates near a rotating, Kerr black hole. It is then shown that when the angular momentum of the black hole goes to zero, the force on the observer reduces to the force on an observer held stationary in Schwarzschild coordinates. As a final consideration, the force on an observer moving in rotating coordinates is derived. Expressing the force in terms of Christoffel symbols in rotating coordinates leads to familiar expressions of the centrifugal and Coriolis forces on the observer. It is envisioned that the techniques presented herein will be most useful to graduate level students, as well as those undergraduate students having experience with general relativity and tensor analysis.

  4. Nuclear reactions

    Nuclear reactions' marks a new development in the study of television as an agency of public policy debate. During the Eighties, nuclear energy became a major international issue. The disasters at Three-mile Island and Chernobyl created a global anxiety about its risks and a new sensitivity to it among politicians and journalists. This book is a case-study into documentary depictions of nuclear energy in television and video programmes and into the interpretations and responses of viewers drawn from many different occupational groupings. How are the complex and specialist arguments about benefit, risk and proof conveyed through the different conventions of commentary, interview and film sequence? What symbolic associations does the visual language of television bring to portrayals of the issue? And how do viewers make sense of various and conflicting accounts, connecting what they see and hear on the screen with their pre-existing knowledge, experience and 'civic' expectations. The authors examine some of the contrasting forms and themes which have been used by programme makers to explain and persuade, and then give a sustained analysis of the nature and sources of viewers' own accounts. 'Nuclear Reactions' inquires into the public meanings surrounding energy and the environment, spelling out in its conclusion some of the implications for future media treatments of this issue. It is also a key contribution to the international literature on 'television knowledge' and the processes of active viewing. (author)

  5. Ground Enterprise Management System Project

    National Aeronautics and Space Administration — Emergent Space Technologies Inc. proposes to develop the Ground Enterprise Management System (GEMS) for spacecraft ground systems. GEMS will provide situational...

  6. Macroscopic QED in linearly responding media and a Lorentz-Force approach to dispersion forces

    Raabe, Christian

    2008-07-08

    In this thesis, a very general quantization scheme for the macroscopic electromagnetic field in arbitrary linearly responding media is presented. It offers a unified approach to QED in such media. Applying the quantization scheme, a theory of the dispersion forces on the basis of the Lorentz force is developed. By regarding the dispersion force as the (ground-state or thermal-state) expectation value of the Lorentz force that acts on appropriately defined charge and current densities, Casimir, Casimir-Polder, and van der Waals forces are united in a very natural way that makes transparent their common physical basis. Application of the theory to planar structures yields generalizations of well-known Lifschitz and Casimir-type formulas. (orig.)

  7. Macroscopic QED in linearly responding media and a Lorentz-Force approach to dispersion forces

    In this thesis, a very general quantization scheme for the macroscopic electromagnetic field in arbitrary linearly responding media is presented. It offers a unified approach to QED in such media. Applying the quantization scheme, a theory of the dispersion forces on the basis of the Lorentz force is developed. By regarding the dispersion force as the (ground-state or thermal-state) expectation value of the Lorentz force that acts on appropriately defined charge and current densities, Casimir, Casimir-Polder, and van der Waals forces are united in a very natural way that makes transparent their common physical basis. Application of the theory to planar structures yields generalizations of well-known Lifschitz and Casimir-type formulas. (orig.)

  8. Malaysia and forced migration

    Arzura Idris

    2012-06-01

    Full Text Available This paper analyzes the phenomenon of “forced migration” in Malaysia. It examines the nature of forced migration, the challenges faced by Malaysia, the policy responses and their impact on the country and upon the forced migrants. It considers forced migration as an event hosting multifaceted issues related and relevant to forced migrants and suggests that Malaysia has been preoccupied with the issue of forced migration movements. This is largely seen in various responses invoked from Malaysia due to “south-south forced migration movements.” These responses are, however, inadequate in terms of commitment to the international refugee regime. While Malaysia did respond to economic and migration challenges, the paper asserts that such efforts are futile if she ignores issues critical to forced migrants.

  9. Three-nucleon forces

    In this paper, the role of three-nucleon forces in ab initio calculations of nuclear systems is investigated. The difference between genuine and induced many-nucleon forces is emphasized. Induced forces arise in the process of solving the nuclear many-body problem as technical intermediaries toward calculationally converged results. Genuine forces make up the Hamiltonian. They represent the chosen underlying dynamics. The hierarchy of contributions arising from genuine two-, three- and many-nucleon forces is discussed. Signals for the need of the inclusion of genuine three-nucleon forces are studied in nuclear systems, technically best under control, especially in three-nucleon and four-nucleon systems. Genuine three-nucleon forces are important for details in the description of some observables. Their contributions to observables are small on the scale set by two-nucleon forces. (author)

  10. Associations of force plate and body-mounted inertial sensor measurements for identification of hind limb lameness in horses.

    Bell, Rhodes P; Reed, Shannon K; Schoonover, Mike J; Whitfield, Chase T; Yonezawa, Yoshiharu; Maki, Hiromitchi; Pai, P Frank; Keegan, Kevin G

    2016-04-01

    OBJECTIVE To investigate associations between inertial sensor and stationary force plate measurements of hind limb lameness in horses. ANIMALS 21 adult horses with no lameness or with mild hind limb lameness. PROCEDURES Horses were instrumented with inertial sensors and evaluated for lameness with a stationary force plate while trotting in a straight line. Inertial sensor-derived measurements of maximum and minimum pelvic height differences between right and left halves of the stride were compared with vertical and horizontal ground reaction forces (GRFs). Stepwise linear regression was performed to investigate the strength of association between inertial sensor measurements of hind limb lameness and amplitude, impulse, and time indices of important events in the vertical and horizontal GRF patterns. RESULTS Difference in minimum pelvic position was moderately (Ra(2) = 0.60) associated with the difference in peak vertical GRF but had little association with any horizontal GRF measurements. Difference in maximum pelvic position was strongly (Ra(2) = 0.77) associated with a transfer of vertical to horizontal ground reaction impulse in the second half of the stance but was not associated with difference in peak vertical GRF. CONCLUSIONS AND CLINICAL RELEVANCE Inertial sensor-derived measurements of asymmetric pelvic fall (difference in minimum pelvic position) indicated a decrease in vertical GRF, but similar measurements of asymmetric pelvis rise (difference in maximum pelvic position) indicated a transfer of vertical to horizontal force impulse in the second half of the stance. Evaluation of both pelvic rise and fall may be important when assessing hind limb lameness in horses. PMID:27027831

  11. Hydrophobic Forces in Flotation

    Pazhianur, Rajesh R

    1999-01-01

    An atomic force microscope (AFM) has been used to conduct force measurements to better understand the role of hydrophobic forces in flotation. The force measurements were conducted between a flat mineral substrate and a hydrophobic glass sphere in aqueous solutions. It is assumed that the hydrophobic glass sphere may simulate the behavior of air bubbles during flotation. The results may provide information relevant to the bubble-particle interactions occurring during flotation. The glass ...

  12. Sprint Acceleration Mechanics: The Major Role of Hamstrings in Horizontal Force Production

    Morin, Jean-Benoît; Gimenez, Philippe; Edouard, Pascal; Arnal, Pierrick; Jiménez-Reyes, Pedro; Samozino, Pierre; Brughelli, Matt; Mendiguchia, Jurdan

    2015-01-01

    Recent literature supports the importance of horizontal ground reaction force (GRF) production for sprint acceleration performance. Modeling and clinical studies have shown that the hip extensors are very likely contributors to sprint acceleration performance. We experimentally tested the role of the hip extensors in horizontal GRF production during short, maximal, treadmill sprint accelerations. Torque capabilities of the knee and hip extensors and flexors were assessed using an isokinetic dynamometer in 14 males familiar with sprint running. Then, during 6-s sprints on an instrumented motorized treadmill, horizontal and vertical GRF were synchronized with electromyographic (EMG) activity of the vastus lateralis, rectus femoris, biceps femoris, and gluteus maximus averaged over the first half of support, entire support, entire swing and end-of-swing phases. No significant correlations were found between isokinetic or EMG variables and horizontal GRF. Multiple linear regression analysis showed a significant relationship (P = 0.024) between horizontal GRF and the combination of biceps femoris EMG activity during the end of the swing and the knee flexors eccentric peak torque. In conclusion, subjects who produced the greatest amount of horizontal force were both able to highly activate their hamstring muscles just before ground contact and present high eccentric hamstring peak torque capability. PMID:26733889

  13. Effective Nuclear Forces

    Calculation of effective forces in nuclei from the Hamada- Johnston potential is described. This work begins from the theories of Brueckner and Bethe and applies them to finite systems. Various renormalizations of the force are discussed. The density dependence of the effective forces is considered in detail. Arguments for the partial breakdown of the shell model in heavy nuclei are given. (author)

  14. Forces in General Relativity

    Ridgely, Charles T.

    2010-01-01

    Many textbooks dealing with general relativity do not demonstrate the derivation of forces in enough detail. The analyses presented herein demonstrate straightforward methods for computing forces by way of general relativity. Covariant divergence of the stress-energy-momentum tensor is used to derive a general expression of the force experienced…

  15. Debunking Coriolis Force Myths

    Shakur, Asif

    2014-01-01

    Much has been written and debated about the Coriolis force. Unfortunately, this has done little to demystify the paradoxes surrounding this fictitious force invoked by an observer in a rotating frame of reference. It is the purpose of this article to make another valiant attempt to slay the dragon of the Coriolis force! This will be done without…

  16. Crossflow force transducer

    A force transducer for measuring lift and drag coefficients for a circular cylinder in turbulent water flow is presented. In addition to describing the actual design and construction of the strain-gauged force- ring based transducer, requirements for obtained valid fluid force test data are discussed, and pertinent flow test experience is related

  17. Ground motion predictions

    Nuclear generated ground motion is defined and then related to the physical parameters that cause it. Techniques employed for prediction of ground motion peak amplitude, frequency spectra and response spectra are explored, with initial emphasis on the analysis of data collected at the Nevada Test Site (NTS). NTS postshot measurements are compared with pre-shot predictions. Applicability of these techniques to new areas, for example, Plowshare sites, must be questioned. Fortunately, the Atomic Energy Commission is sponsoring complementary studies to improve prediction capabilities primarily in new locations outside the NTS region. Some of these are discussed in the light of anomalous seismic behavior, and comparisons are given showing theoretical versus experimental results. In conclusion, current ground motion prediction techniques are applied to events off the NTS. Predictions are compared with measurements for the event Faultless and for the Plowshare events, Gasbuggy, Cabriolet, and Buggy I. (author)

  18. Nuclear reactions. An introduction

    Modern, self-contained introduction to the subject matter. Emphasizes the interplay between theory and experiment. Course-tested tutorial style, contains many derivations. Nuclei and nuclear reactions offer a unique setting for investigating three (and in some cases even all four) of the fundamental forces in nature. Nuclei have been shown - mainly by performing scattering experiments with electrons, muons, and neutrinos - to be extended objects with complex internal structures: constituent quarks; gluons, whose exchange binds the quarks together; sea-quarks, the ubiquitous virtual quark-antiquark pairs and, last but not least, clouds of virtual mesons, surrounding an inner nuclear region, their exchange being the source of the nucleon-nucleon interaction. The interplay between the (mostly attractive) hadronic nucleon-nucleon interaction and the repulsive Coulomb force is responsible for the existence of nuclei; their degree of stability, expressed in the details and limits of the chart of nuclides; their rich structure and the variety of their interactions. Despite the impressive successes of the classical nuclear models and of ab-initio approaches, there is clearly no end in sight for either theoretical or experimental developments as shown e.g. by the recent need to introduce more sophisticated three-body interactions to account for an improved picture of nuclear structure and reactions. Yet, it turns out that the internal structure of the nucleons has comparatively little influence on the behavior of the nucleons in nuclei, and nuclear physics - especially nuclear structure and reactions - is thus a field of science in its own right, without much recourse to subnuclear degrees of freedom. This book collects essential material that was presented in the form of lectures notes in nuclear physics courses for graduate students at the University of Cologne. It follows the course's approach, conveying the subject matter by combining experimental facts and experimental

  19. Grounded Theory approach

    Ali Rabbani Khorasghani

    2010-01-01

    Full Text Available AbstractAccording to social changes in global level, social scientist introduced new theories to explanation of socialphenomena. According to appearance new theories, research methods have changed. The Idea is that,Simultaneity with Appearance post positivist theories, research approaches such a grounded theory hasestablished. This method, acts in the base of qualitative methods and use systematic complex of multipleProcedures to gathering data for theory development upon induction. This method with characteristics as ifflexibility, reflexivity, has caused many of researchers used it. In the present article, we paid to introductionof grounded theory and its critics.

  20. Dynamic Ground Clearance

    Hamache, Violette

    2013-01-01

    The purpose of this work is to develop a test method which will consider the variation of the ground clearance when driving, the so-called dynamic ground clearance. This has been done through the analysis of a specific application: the tractors in grain used in Brazil. Series of real life tests are run in order to obtain data on the tire compressions and the suspension travels. The tractor used is a 6x4 and is loaded with a trailer. When investigating critical cases, the minimum dynamic groun...

  1. Polarization phenomena in collinear reactions

    Moravcsik, Michael J.; Arash, Firooz

    1985-06-01

    It is shown for a collinear reaction containing four particles with arbitrary spins which amplitudes remain nonzero and how they are related to the observables. In terms of primary observables all submatrices relating products of amplitudes to observables either vanish or turn into one-by-one submatrices, except the 8i types which may turn into three-by-three submatrices, but these latter submatrices are mostly avoidable when determining amplitudes. In terms of the secondary observables the 1M and 2i submatrices are slightly larger. Specifically, it is shown that in collinear reactions all observables in which only one particle is polarized (no matter how) vanish. Since reactions at very high energies are expected to be predominantly very close to being collinear, the smallness of such observables in such reactions can be expected on general grounds but polarization effects involving observables with more than one polarized particle can very well be very large. An iterative approximation method for the polarization analysis of reactions at very high energies is suggested. The results of this paper are also applicable to all models in which helicity conservation holds, since they are, for all t values, formally identical with collinear reactions.

  2. Polarization phenomena in collinear reactions

    It is shown for a collinear reaction containing four particles with arbitrary spins which amplitudes remain nonzero and how they are related to the observables. In terms of primary observables all submatrices relating products of amplitudes to observables either vanish or turn into one-by-one submatrices, except the 8/sub i/ types which may turn into three-by-three submatrices, but these latter submatrices are mostly avoidable when determining amplitudes. In terms of the secondary observables the 1/sub M/ and 2/sub i/ submatrices are slightly larger. Specifically, it is shown that in collinear reactions all observables in which only one particle is polarized (no matter how) vanish. Since reactions at very high energies are expected to be predominantly very close to being collinear, the smallness of such observables in such reactions can be expected on general grounds but polarization effects involving observables with more than one polarized particle can very well be very large. An iterative approximation method for the polarization analysis of reactions at very high energies is suggested. The results of this paper are also applicable to all models in which helicity conservation holds, since they are, for all t values, formally identical with collinear reactions

  3. Efficacy of climate forcings

    Hansen, J.; Sato, M.; Ruedy, R.; Nazarenko, L.; Lacis, A.; Schmidt, G. A.; Russell, G.; Aleinov, I.; Bauer, M.; Bauer, S.; Bell, N.; Cairns, B.; Canuto, V.; Chandler, M.; Cheng, Y.; Del Genio, A.; Faluvegi, G.; Fleming, E.; Friend, A.; Hall, T.; Jackman, C.; Kelley, M.; Kiang, N.; Koch, D.; Lean, J.; Lerner, J.; Lo, K.; Menon, S.; Miller, R.; Minnis, P.; Novakov, T.; Oinas, V.; Perlwitz, Ja.; Perlwitz, Ju.; Rind, D.; Romanou, A.; Shindell, D.; Stone, P.; Sun, S.; Tausnev, N.; Thresher, D.; Wielicki, B.; Wong, T.; Yao, M.; Zhang, S.

    2005-09-01

    We use a global climate model to compare the effectiveness of many climate forcing agents for producing climate change. We find a substantial range in the "efficacy" of different forcings, where the efficacy is the global temperature response per unit forcing relative to the response to CO2 forcing. Anthropogenic CH4 has efficacy ˜110%, which increases to ˜145% when its indirect effects on stratospheric H2O and tropospheric O3 are included, yielding an effective climate forcing of ˜0.8 W/m2 for the period 1750-2000 and making CH4 the largest anthropogenic climate forcing other than CO2. Black carbon (BC) aerosols from biomass burning have a calculated efficacy ˜58%, while fossil fuel BC has an efficacy ˜78%. Accounting for forcing efficacies and for indirect effects via snow albedo and cloud changes, we find that fossil fuel soot, defined as BC + OC (organic carbon), has a net positive forcing while biomass burning BC + OC has a negative forcing. We show that replacement of the traditional instantaneous and adjusted forcings, Fi and Fa, with an easily computed alternative, Fs, yields a better predictor of climate change, i.e., its efficacies are closer to unity. Fs is inferred from flux and temperature changes in a fixed-ocean model run. There is remarkable congruence in the spatial distribution of climate change, normalized to the same forcing Fs, for most climate forcing agents, suggesting that the global forcing has more relevance to regional climate change than may have been anticipated. Increasing greenhouse gases intensify the Hadley circulation in our model, increasing rainfall in the Intertropical Convergence Zone (ITCZ), Eastern United States, and East Asia, while intensifying dry conditions in the subtropics including the Southwest United States, the Mediterranean region, the Middle East, and an expanding Sahel. These features survive in model simulations that use all estimated forcings for the period 1880-2000. Responses to localized forcings, such

  4. Quantum fictitious forces

    Bialynicki-Birula, I; Cirone, M.A.; Dahl, Jens Peder;

    2002-01-01

    We present Heisenberg's equation of motion for the radial variable of a free non-relativistic particle in D dimensions. The resulting radial force consists of three contributions: (i) the quantum fictitious force which is either attractive or repulsive depending on the number of dimensions, (ii......) a singular quantum force located at the origin, and (iii) the centrifugal force associated with non-vanishing angular momentum. Moreover, we use Heisenberg's uncertainty relation to introduce a lower bound for the kinetic energy of an ensemble of neutral particles. This bound is quadratic in the number...... of atoms and can be traced back to the repulsive quantum fictitious potential. All three forces arise for a free particle: "Force without force"....

  5. Forces in molecules.

    Hernández-Trujillo, Jesús; Cortés-Guzmán, Fernando; Fang, De-Chai; Bader, Richard F W

    2007-01-01

    Chemistry is determined by the electrostatic forces acting within a collection of nuclei and electrons. The attraction of the nuclei for the electrons is the only attractive force in a molecule and is the force responsible for the bonding between atoms. This is the attractive force acting on the electrons in the Ehrenfest force and on the nuclei in the Feynman force, one that is countered by the repulsion between the electrons in the former and by the repulsion between the nuclei in the latter. The virial theorem relates these forces to the energy changes resulting from interactions between atoms. All bonding, as signified by the presence of a bond path, has a common origin in terms of the mechanics determined by the Ehrenfest, Feynman and virial theorems. This paper is concerned in particular with the mechanics of interaction encountered in what are classically described as 'nonbonded interactions'--are atoms that 'touch' bonded or repelling one another? PMID:17328425

  6. Quantum fictitious forces

    Bialynicki-Birula, I; Cirone, M.A.; Dahl, Jens Peder; Seligman, T.H.; Straub, F.; Schleich, W.P.

    We present Heisenberg's equation of motion for the radial variable of a free non-relativistic particle in D dimensions. The resulting radial force consists of three contributions: (i) the quantum fictitious force which is either attractive or repulsive depending on the number of dimensions, (ii) a...... singular quantum force located at the origin, and (iii) the centrifugal force associated with non-vanishing angular momentum. Moreover, we use Heisenberg's uncertainty relation to introduce a lower bound for the kinetic energy of an ensemble of neutral particles. This bound is quadratic in the number of...... atoms and can be traced back to the repulsive quantum fictitious potential. All three forces arise for a free particle: "Force without force"....

  7. Forced forward smoldering experiments in microgravity

    Bar-Ilan, Amnon; Rein, Guillermo; Fernandez-Pello, A Carlos; Torero, J.l.; Urban, D L

    2004-01-01

    Results from two forward forced-flow smolder tests on polyurethane foam using air as oxidizer conducted aboard the NASA Space Shuttle (STS-105 and STS-108 missions) are presented in this work. The two tests provide the only presently available forward smolder data in microgravity. A complimentary series of ground-based tests were also conducted to determine, by comparison with the microgravity data, the effect of gravity on the forward smolder propagation. The objective of the study is to pro...

  8. Direct SW aerosol radiative forcing over Portugal

    D. Santos

    2008-05-01

    Full Text Available The estimation of radiative forcing due to desert dust and forest fires aerosols is a very important issue since these particles are very efficient at scattering and absorbing both short and longwave radiation. In this work, the evaluation of the aerosol radiative forcing at the top of the atmosphere over the south of Portugal is made, particularly in the regions of Évora and of Cabo da Roca.

    The radiative transfer calculations combine ground-based and satellite measurements, to estimate the top of the atmosphere direct SW aerosol radiative forcing. The method developed to retrieve the surface spectral reflectance is also presented, based on ground-based measurements of the aerosol optical properties combined with the satellite-measured radiances.

    The aerosol direct radiative effect is shown to be very sensitive to the underlying surface, since different surface spectral reflectance values may originate different forcing values. The results obtained also illustrate the importance of considering the actual aerosol properties, in this case measured by ground-based instrumentation, particularly the aerosol single scattering albedo, because different aerosol single scattering albedo values can flip the sign of the direct SW aerosol radiative forcing.

    The instantaneous direct SW aerosol radiative forcing values obtained at the top of the atmosphere are, in the majority of the cases, negative, indicating a tendency for cooling the Earth. For Desert Dust aerosols, over Évora land region, the average forcing efficiency is estimated to be −25 W/m2/AOT0.55 whereas for Cabo da Roca area, the average forcing efficiency is −46 W/m2/AOT0.55. In the presence of Forest Fire aerosols, over Cabo da Roca region, the average value of forcing efficiency is −28 W/m2/AOT0.55 and over Évora region an average value of −33 W/m2/AOT0.55 is found.

  9. The LOFT Ground Segment

    Bozzo, E.; Antonelli, A.; Argan, A.;

    2014-01-01

    we summarize the planned organization of the LOFT ground segment (GS), as established in the mission Yellow Book 1 . We describe the expected GS contributions from ESA and the LOFT consortium. A review is provided of the planned LOFT data products and the details of the data flow, archiving and...

  10. Coal and coffee grounds

    Landais, C.

    The Sopad Nestle plant in Dieppe is the number 1 plant in France producing soluble coffee and chicory. Since 1983, it recovers and uses a production byproduct, coffee grounds as fuel, with coal, with an ignifluid boiler (hot fluidized bed), built by Fives-Cail-Babcock.

  11. Collison and Grounding

    Wang, G.; Ji, C.; Kuhala, P.;

    2006-01-01

    COMMITTEE MANDATE Concern for structural arrangements on ships and floating structures with regard to their integrity and adequacy in the events of collision and grounding, with the view towards risk assessment and management. Consideration shall be given to the frequency of occurrence, the...

  12. Singlet Ground State Magnetism:

    Loidl, A.; Knorr, K.; Kjems, Jørgen;

    1979-01-01

    The magneticGamma 1 –Gamma 4 exciton of the singlet ground state system TbP has been studied by inelastic neutron scattering above the antiferromagnetic ordering temperature. Considerable dispersion and a pronounced splitting was found in the [100] and [110] directions. Both the band width and the...

  13. Echoes at Ground Zero

    Chronicle of Higher Education, 2006

    2006-01-01

    An excerpt from the opening piece in "Everything That Rises: A Book of Convergences" by Lawrence Weschler is presented where the author is talking with Joel Meyerowitz, the only photographer granted unimpeded access to the clean-up operations at ground zero after the terrorist attacks of September 11, 2001. The two discuss the parallels between…

  14. Shadow of ground zero

    Haaland, C.M.

    1984-01-01

    The history of the development of nuclear weapons starting with the detonation of the A-bombs on Japan is reviewed. An overview of nuclear weapon effects is presented. The effects of electromagnetic pulse (EMP), initial nuclear radiation, thermal radiation and blast are discussed with reference to how people outside can survive when ground zero is only a few miles away. 8 references. (ACR)

  15. Technology at Ground Zero.

    Techniques: Connecting Education and Careers, 2002

    2002-01-01

    Describes the robots used to aid in rescue and recovery at Ground Zero after the September 11, 2001 attack on the World Trade Center. The robots were developed as a result of national Science Foundation Quick Response Research Awards. Describes several awards that were made following the attack. (JOW)

  16. Four frequency ground scatterometer

    Dickerson, E. T.

    1982-01-01

    The FM-CW Radar, used as a microwave scatterometer is described. Scatterometer system design, scatterometer system calibration, parameter calculation and correction for data acquisition, ground scatterometer data acquistion at Jornada Experimental Range, and Kansas radar cross-calibration test are discussed.

  17. Force field development on pigments of photosystem 2 reaction centre

    Palenčár, Peter

    2005-01-01

    Roč. 43, č. 3 (2005), s. 417-420. ISSN 0044-5231 R&D Projects: GA ČR GP206/02/D177 Institutional research plan: CEZ:AV0Z50510513; CEZ:AV0Z60870520 Keywords : photosystem 2 Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.750, year: 2005

  18. Force field development on pigments of photosystem 2 reaction centre

    Palenčár, P.; Vácha, František; Kutý, Michal

    2005-01-01

    Roč. 43, - (2005), 417-420. ISSN 0300-3604 R&D Projects: GA ČR GP206/02/D177 Institutional research plan: CEZ:AV0Z50510513; CEZ:AV0Z60870520 Keywords : photosystem 2 Subject RIV: BO - Biophysics Impact factor: 0.810, year: 2005

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

    Jensen, Søren; Olsen, Jakob Lind; Thorsteinsson, Sune; Hansen, Ole; Quaade, Ulrich

    2007-01-01

    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...

  20. Chain reaction

    Chain Reaction is a work of recent American political history. It seeks to explain how and why America came to depend so heavily on its experts after World War II, how those experts translated that authority into political clout, and why that authority and political discretion declined in the 1970s. The author's research into the internal memoranda of the Atomic Energy Commission substantiates his argument in historical detail. It was not the ravages of American anti-intellectualism, as so many scholars have argued, that brought the experts back down to earth. Rather, their decline can be traced to the very roots of their success after World War II. The need to over-state anticipated results in order to garner public support, incessant professional and bureaucratic specialization, and the sheer proliferation of expertise pushed arcane and insulated debates between experts into public forums at the same time that a broad cross section of political participants found it easier to gain access to their own expertise. These tendencies ultimately undermined the political influence of all experts. (author)

  1. Dynamics of thermal Casimir-Polder forces on polar molecules

    Ellingsen, S. A.; Buhmann, S. Y.; Scheel, S.

    2008-01-01

    We study the influence of thermal Casimir-Polder forces on the near-surface trapping of cold polar molecules, with emphasis on LiH and YbF near an Au surface at room temperature. We show that for a molecule initially prepared in its electronic and rovibrational ground state, the Casimir-Polder force oscillates with the molecule-wall separation. The non-resonant force contribution and the evanescent part of the resonant force contribution almost exactly cancel at high temperature which results...

  2. Preponderance of ground states with positive parity

    We investigate analytically and numerically a random-matrix model for m fermions occupying ℓ1 single-particle states with positive parity and ℓ2 single-particle states with negative parity and interacting through random two-body forces that conserve parity. The single-particle states are completely degenerate and carry no further quantum numbers. We compare spectra of many-body states with positive and with negative parity. We show that in the dilute limit defined by 1 « m « ℓ1, ℓ2, ground states with positive and with negative parity occur with equal probability. Differences in the ground-state probabilities are, thus, a finite-size effect and are mainly due to different dimensions of the Hilbert spaces of either parity. (author)

  3. Variable Acceleration Force Calibration System (VACS)

    Rhew, Ray D.; Parker, Peter A.; Johnson, Thomas H.; Landman, Drew

    2014-01-01

    Conventionally, force balances have been calibrated manually, using a complex system of free hanging precision weights, bell cranks, and/or other mechanical components. Conventional methods may provide sufficient accuracy in some instances, but are often quite complex and labor-intensive, requiring three to four man-weeks to complete each full calibration. To ensure accuracy, gravity-based loading is typically utilized. However, this often causes difficulty when applying loads in three simultaneous, orthogonal axes. A complex system of levers, cranks, and cables must be used, introducing increased sources of systematic error, and significantly increasing the time and labor intensity required to complete the calibration. One aspect of the VACS is a method wherein the mass utilized for calibration is held constant, and the acceleration is changed to thereby generate relatively large forces with relatively small test masses. Multiple forces can be applied to a force balance without changing the test mass, and dynamic forces can be applied by rotation or oscillating acceleration. If rotational motion is utilized, a mass is rigidly attached to a force balance, and the mass is exposed to a rotational field. A large force can be applied by utilizing a large rotational velocity. A centrifuge or rotating table can be used to create the rotational field, and fixtures can be utilized to position the force balance. The acceleration may also be linear. For example, a table that moves linearly and accelerates in a sinusoidal manner may also be utilized. The test mass does not have to move in a path that is parallel to the ground, and no re-leveling is therefore required. Balance deflection corrections may be applied passively by monitoring the orientation of the force balance with a three-axis accelerometer package. Deflections are measured during each test run, and adjustments with respect to the true applied load can be made during the post-processing stage. This paper will

  4. Rate of force development

    Maffiuletti, Nicola A; Aagaard, Per; Blazevich, Anthony J;

    2016-01-01

    The evaluation of rate of force development during rapid contractions has recently become quite popular for characterising explosive strength of athletes, elderly individuals and patients. The main aims of this narrative review are to describe the neuromuscular determinants of rate of force devel....... Therefore, we provide evidence-based practical recommendations for rational quantification of rate of force development in both laboratory and clinical settings.......The evaluation of rate of force development during rapid contractions has recently become quite popular for characterising explosive strength of athletes, elderly individuals and patients. The main aims of this narrative review are to describe the neuromuscular determinants of rate of force...... development and to discuss various methodological considerations inherent to its evaluation for research and clinical purposes. Rate of force development (1) seems to be mainly determined by the capacity to produce maximal voluntary activation in the early phase of an explosive contraction (first 50-75 ms...

  5. Nonlinear Dynamic Force Spectroscopy

    Björnham, Oscar

    2016-01-01

    Dynamic force spectroscopy (DFS) is an experimental technique that is commonly used to assess information of the strength, energy landscape, and lifetime of noncovalent bio-molecular interactions. DFS traditionally requires an applied force that increases linearly with time so that the bio-complex under investigation is exposed to a constant loading rate. However, tethers or polymers can modulate the applied force in a nonlinear regime. For example, bacterial adhesion pili and polymers with worm-like chain properties are examples of structures that show nonlinear force responses. In these situations, the theory for traditional DFS cannot be readily applied. In this work we expand the theory for DFS to also include nonlinear external forces while still maintaining compatibility with the linear DFS theory. To validate the theory we modeled a bio-complex expressed on a stiff, an elastic and a worm-like chain polymer, using Monte Carlo methods, and assessed the corresponding rupture force spectra. It was found th...

  6. Relativistic Linear Restoring Force

    Clark, D.; Franklin, J.; Mann, N.

    2012-01-01

    We consider two different forms for a relativistic version of a linear restoring force. The pair comes from taking Hooke's law to be the force appearing on the right-hand side of the relativistic expressions: d"p"/d"t" or d"p"/d["tau"]. Either formulation recovers Hooke's law in the non-relativistic limit. In addition to these two forces, we…

  7. Casimir force of expulsion

    Fateev, Evgeny G.

    2012-01-01

    The possibility in principle is shown that the noncompensated Casimir force can exist in nanosized open metal cavities. The force shows up as time-constant expulsion of open cavities toward their least opening. The optimal parameters of the angles of the opening, of "generating lines" of cavities and their lengths are found at which the expulsive force is maximal. The theory is created for trapezoid configurations, in particular for parallel mirrors which experience both the transverse Casimi...

  8. Ground movements associated with gas hydrate production

    This report deals with a study directed towards a modeling effort on production related ground movements and subsidence resulting from hydrate dissociation. The goal of this research study was to evaluate whether there could be subsidence related problems that could be an impediment to hydrate production. During the production of gas from a hydrate reservoir, it is expected that porous reservoir matrix becomes more compressible which may cause reservoir compression (compaction) under the influence of overburden weight. The overburden deformations can propagate its influence upwards causing subsidence near the surface where production equipment will be located. In the present study, the reservoir compaction is modeled by using the conventional ''stress equilibrium'' approach. In this approach, the overburden strata move under the influence of body force (i.e. self weight) in response to the ''cavity'' generated by reservoir depletion. The present study is expected to provide a ''lower bound'' solution to the subsidence caused by hydrate reservoir depletion. The reservoir compaction anticipated during hydrate production was modeled by using the finite element method, which is a powerful computer modeling technique. The ground movements at the reservoir roof (i.e. reservoir compression) cause additional stresses and disturbance in the overburden strata. In this study, the reservoir compaction was modeled by using the conventional ''stress equilibrium'' approach. In this approach, the overburden strata move under the influence of body force (i.e. self weight) in response to the ''cavity'' generated by reservoir depletion. The resulting stresses and ground movements were computed by using the finite element method. Based on the parameters used in this investigation, the maximum ground subsidence could vary anywhere from 0.50 to 6.50 inches depending on the overburden depth and the size of the depleted hydrate reservoir

  9. Casimir-Polder forces: A nonperturbative approach

    Within the frame of macroscopic QED in linear, causal media, we study the radiation force of Casimir-Polder type acting on an atom which is positioned near dispersing and absorbing magnetodielectric bodies and initially prepared in an arbitrary electronic state. It is shown that minimal and multipolar coupling lead to essentially the same lowest-order perturbative result for the force acting on an atom in an energy eigenstate. To go beyond perturbation theory, the calculations are based on the exact center-of-mass equation of motion. For a nondriven atom in the weak-coupling regime, the force as a function of time is a superposition of force components that are related to the electronic density matrix elements at a chosen time. Even the force component associated with the ground state is not derivable from a potential in the ususal way, because of the position dependence of the atomic polarizability. Further, when the atom is initially prepared in a coherent superposition of energy eigenstates, then temporally oscillating force components are observed, which are due to the interaction of the atom with both electric and magnetic fields

  10. Theory of intermolecular forces

    Margenau, H; Ter Haar, D

    1971-01-01

    Theory of Intermolecular Forces deals with the exposition of the principles and techniques of the theory of intermolecular forces. The text focuses on the basic theory and surveys other aspects, with particular attention to relevant experiments. The initial chapters introduce the reader to the history of intermolecular forces. Succeeding chapters present topics on short, intermediate, and long range atomic interactions; properties of Coulomb interactions; shape-dependent forces between molecules; and physical adsorption. The book will be of good use to experts and students of quantum mechanics

  11. Intermolecular and surface forces

    Israelachvili, Jacob N

    2011-01-01

    This reference describes the role of various intermolecular and interparticle forces in determining the properties of simple systems such as gases, liquids and solids, with a special focus on more complex colloidal, polymeric and biological systems. The book provides a thorough foundation in theories and concepts of intermolecular forces, allowing researchers and students to recognize which forces are important in any particular system, as well as how to control these forces. This third edition is expanded into three sections and contains five new chapters over the previous edition.· starts fr

  12. No fifth force?

    Maggs, William Ward

    Hopes that geophysicists might be able to document a fifth force of nature have diminished, as new measurements and analyses of earlier geodetic experiments have yielded no solid evidence of a non-Newtonian component of gravity.Modern physics recognizes four fundamental forces with distinct spheres of influence: The strong and weak nuclear forces operate over the range of one atom, while gravity and electromagnetism have an infinite range. Gravity measurements over a few centimeters in laboratories and over millions of kilometers in space continue to buttress Issac Newton's conclusion that the gravitational force between two objects decreases as the square of the distance between them.

  13. GAINING GREEN GROUND

    LAN XINZHEN

    2011-01-01

    Anational technical standard for electric vehicles (EVs) may be set by year's end,said National Business Daily citing an industry insider from the Society of Automotive Engineers of China on October 12.The issuance of the national technical standard may forcefully promote the commercialization and industrialization of EVs in China.

  14. Ground motion effects

    Ground motion caused by natural earthquakes or by nuclear explosion causes buildings and other structures to respond in such manner as possibly to have high unit stresses and to be subject to damage or-in some cases-collapse. Even minor damage may constitute a hazard to persons within or adjacent to buildings. The risk of damage may well be the governing restraint on the uses of nuclear energy for peaceful purposes. Theory is advanced regarding structural-dynamic response but real buildings and structures are complex, highly variable, and often difficult to model realistically. This paper discusses the state of knowledge, the art of damage prediction and safety precautions, and shows ground motion effects from explosions of underground nuclear devices in the continental United States including events Salmon, Gasbuggy, Boxcar, Faultless and Benham. (author)

  15. Decentralized Ground Staff Scheduling

    Sørensen, M. D.; Clausen, Jens

    2002-01-01

    Typically, ground staff scheduling is centrally planned for each terminal in an airport. The advantage of this is that the staff is efficiently utilized, but a disadvantage is that staff spends considerable time walking between stands. In this paper a decentralized approach for ground staff...... scheduling is investigated. The airport terminal is divided into zones, where each zone consists of a set of stands geographically next to each other. Staff is assigned to work in only one zone and the staff scheduling is planned decentralized for each zone. The advantage of this approach is that the staff...... work in a smaller area of the terminal and thus spends less time walking between stands. When planning decentralized the allocation of stands to flights influences the staff scheduling since the workload in a zone depends on which flights are allocated to stands in the zone. Hence solving the problem...

  16. Grounded Theory approach

    Ali Rabbani Khorasghani; Mohammad Abbaszadeh

    2010-01-01

    AbstractAccording to social changes in global level, social scientist introduced new theories to explanation of socialphenomena. According to appearance new theories, research methods have changed. The Idea is that,Simultaneity with Appearance post positivist theories, research approaches such a grounded theory hasestablished. This method, acts in the base of qualitative methods and use systematic complex of multipleProcedures to gathering data for theory development upon induction. This meth...

  17. Identification of Motive Forces on the Whole Body System during Walking

    Raghdan J. AlKhoury

    2010-01-01

    Full Text Available Motive forces by muscles are applied to different parts of the human body in a periodic fashion when walking at a uniform rate. In this study, the whole human body is modeled as a multidegree of freedom (MDOF system with seven degrees of freedom. In view of the changing contact conditions with the ground due to alternating feet movements, the system under study is considered piecewise time invariant for each half-period when one foot is in contact with the ground. Forces transmitted from the body to the ground while walking at a normal pace are experimentally measured and numerically simulated. Fourth-order Runge-Kutta method is employed to numerically simulate the forces acting on different masses of the body. An optimization problem is formulated with the squared difference between the measured and simulated forces transmitted to the ground as the objective function, and the motive forces on the body masses as the design variables to solve.

  18. Aerodynamic ground effect in fruitfly sized insect takeoff

    Kolomenskiy, Dmitry; Engels, Thomas; Liu, Hao; Schneider, Kai; Nave, Jean-Christophe

    2015-01-01

    Flapping-wing takeoff is studied using numerical modelling, considering the voluntary takeoff of a fruitfly as reference. The parameters of the model are then varied to explore the possible effects of interaction between the flapping-wing model and the ground plane. The numerical method is based on a three-dimensional Navier-Stokes solver and a simple flight dynamics solver that accounts for the body weight, inertia, and the leg thrust. Forces, power and displacements are compared for takeoffs with and without ground effect. Natural voluntary takeoff of a fruitfly, modified takeoffs and hovering are analyzed. The results show that the ground effect during the natural voluntary takeoff is negligible. In the modified takeoffs, the ground effect does not produce any significant increase of the vertical force neither. Moreover, the vertical force even drops in most of the cases considered. There is a consistent increase of the horizontal force, and a decrease of the aerodynamic power, if the rate of climb is suff...

  19. Calculation of ground vibration spectra from heavy military vehicles

    Krylov, V. V.; Pickup, S.; McNuff, J.

    2010-07-01

    The demand for reliable autonomous systems capable to detect and identify heavy military vehicles becomes an important issue for UN peacekeeping forces in the current delicate political climate. A promising method of detection and identification is the one using the information extracted from ground vibration spectra generated by heavy military vehicles, often termed as their seismic signatures. This paper presents the results of the theoretical investigation of ground vibration spectra generated by heavy military vehicles, such as tanks and armed personnel carriers. A simple quarter car model is considered to identify the resulting dynamic forces applied from a vehicle to the ground. Then the obtained analytical expressions for vehicle dynamic forces are used for calculations of generated ground vibrations, predominantly Rayleigh surface waves, using Green's function method. A comparison of the obtained theoretical results with the published experimental data shows that analytical techniques based on the simplified quarter car vehicle model are capable of producing ground vibration spectra of heavy military vehicles that reproduce basic properties of experimental spectra.

  20. Climate forcings and feedbacks

    Hansen, James

    1993-01-01

    Global temperature has increased significantly during the past century. Understanding the causes of observed global temperature change is impossible in the absence of adequate monitoring of changes in global climate forcings and radiative feedbacks. Climate forcings are changes imposed on the planet's energy balance, such as change of incoming sunlight or a human-induced change of surface properties due to deforestation. Radiative feedbacks are radiative changes induced by climate change, such as alteration of cloud properties or the extent of sea ice. Monitoring of global climate forcings and feedbacks, if sufficiently precise and long-term, can provide a very strong constraint on interpretation of observed temperature change. Such monitoring is essential to eliminate uncertainties about the relative importance of various climate change mechanisms including tropospheric sulfate aerosols from burning of coal and oil smoke from slash and burn agriculture, changes of solar irradiance changes of several greenhouse gases, and many other mechanisms. The considerable variability of observed temperature, together with evidence that a substantial portion of this variability is unforced indicates that observations of climate forcings and feedbacks must be continued for decades. Since the climate system responds to the time integral of the forcing, a further requirement is that the observations be carried out continuously. However, precise observations of forcings and feedbacks will also be able to provide valuable conclusions on shorter time scales. For example, knowledge of the climate forcing by increasing CFC's relative to the forcing by changing ozone is important to policymakers, as is information on the forcing by CO2 relative to the forcing by sulfate aerosols. It will also be possible to obtain valuable tests of climate models on short time scales, if there is precise monitoring of all forcings and feedbacks during and after events such as a large volcanic eruption

  1. On the work of internal forces

    Guemez, Julio; Brito, Lucilia

    2016-01-01

    We discuss the role of the internal forces and how their work changes the energy of a system. We illustrate the contribution of the internal work to the variation of the system's energy, using a pure mechanical example, a thermodynamical system and an example from electromagnetism. We emphasize that internal energy variations related to the work of the internal forces should be pinpointed in the classroom and placed on the same footing as other internal energy variations such as those caused by temperature changes or by chemical reactions.

  2. Calculation of astrophysical reaction rate of 82Ge(n,γ)83Ge

    WANG Mian; CHEN Yong-Shou; LI Zhi-Hong; LIU Wei-Ping; SHU Neng-Chuan

    2009-01-01

    The neutron capture reaction on a neutron-rich near closed-shell nucleus 82Ge may play an important role in the r-process following the fallout from nuclear statistical equilibrium in core-collapse supernovae.By carrying out a DWBA analysis for the experimental angular distribution of 82Ge(d, p)83Ge reaction we obtain the single particle spectroscopic factors, S2,5/2 and S0,1/2 for the ground and first excited states of 83Ge=82Ge(⊕)n, respectively. And then these spectroscopic factors are used to calculate the direct capture cross sections for the 82Ge(n, γ)83Ge reaction at energies of astrophysical interest. The optical potential for neutron scattering on unstable nucleus 82Ge is not known experimentally. We employed a real folding potential which was calculated by using the proper 82Ge density distribution and an effective nucleon-nucleon force DDM3Y.The neutron capture reactions on neutron-rich closed-shell nuclei are expected to be dominated by the direct capture to bound states. We will show that the direct capture rates on these nuclei are sensitive to the structure of the low-lying states.

  3. Capture reactions at low energies

    Some few body capture reaction studies at low energies are reviewed. The emphasis is on the use of polarized beams. New calculations of n+d and p+d capture had just recently been completed by the Los Alamos group (Friar, Gibson, and Payne). Their results are in good agreement with existing data, and emphasize the importance of meson exchange current effects in these processes at thermal energies. The effects of M1 radiation can be seen in the vector analyzing power of the p+d radiative capture reaction from its interference with E1 radiation. The vector analyzing powers of the rvec p+T → 4He + γ reaction can be used to search for M1 radiation in 4He. Low energy data show a substantial b1 coefficient which can only be accounted for with a substantial M1 contribution. The author is also working on studying the rvec d+T and rvec d+3He capture reactions in the region of the fusion resonance. His (published) rvec d+T capture data indicate that the reaction goes via ∼95% S = 3/2, E1 capture with small S = 1/2, E1 and small M1 admixtures. In the course of obtaining the d+T and d+3He data, he realized that he could use his spectra to obtain the ground state widths of 5He and 5Li. Finally, he will discuss the d+d reaction at very low energies. The simplest picture of this reaction dominated by S wave capture to the D-state below 1 MeV

  4. Force Concept Inventory.

    Hestenes, David; And Others

    1992-01-01

    Reports the rationale, design, validation, and uses of the "Force Concept Inventory," an instrument to assess the students' beliefs on force. Includes results and implications of two studies that compared the inventory with the "Mechanics Baseline." Includes a copy of the instrument. (MDH)

  5. Influence of Whole Body Vibration and Specific Warm-ups on Force during an Isometric Mid-Thigh Pull

    Vanessa L. Cazás-Moreno

    2015-10-01

    Full Text Available Purpose: The purpose of this study was to investigate the effects of general and specific warm-up protocols on rate of force development (RFD, relative RFD (rRFD, ground reaction force (GRF and relative ground reaction force (rGRF during an isometric mid-thigh pull (IMTP, after WBV exposure. Methods: Fifteen healthy recreationally trained males  (age: 24.1 ± 2.3 yrs, height: 72.9 ± 7.8 cm; mass: 86.9 ± 8.3 completed five protocols: baseline, isometric vibration (iVib, isometric no vibration (iNV, dynamic vibration (dVib and dynamic no vibration (dNV. The baseline was completed without any warm-up prior to the IMTP. The intervention protocols had the same prescription of 4 sets of 30-second bouts of quarter squats (dynamic [DQS] and isometric [IQS] on the WBV platform with or without vibration. Following a one-minute rest period after each protocol, participants completed three maximal IMTPs. Results: Repeated measures ANOVA with a Bonferroni post hoc demonstrated that RFD in dNV (7657.8 ± 2292.5 N/s was significantly greater than iVib (7156.4 ± 2170.0 N/s. However, the other experimental trials for RFD demonstrated no significant differences (p>0.05. There were also no significant differences for rRFD, GRF or rGRF between protocols. Conclusion: These results demonstrate that a dynamic warm-up without WBV elicits greater RFD than an isometric warm-up with WBV prior to a maximal isometric exercise. Further research needs to be investigated utilizing dynamic and isometric warm-ups in conjunction with WBV and power output.Keywords: males, recreationally trained, power 

  6. Knee Contact Force in Subjects with Symmetrical OA Grades: Differences between OA Severities

    Richards, C; Higginson, J.S.

    2010-01-01

    In using musculoskeletal models, researchers can calculate muscle forces, and subsequently joint contact forces, providing insight into joint loading and the progression of such diseases as osteoarthritis (OA). The purpose of this study was to estimate the knee contact force (KCF) in patients with varying degrees of OA severity using muscle forces and joint reaction forces derived from OpenSim. Walking data was obtained from individuals with severe (n=2), moderate (n=10) and no signs of OA (n...

  7. Attractive optical forces from black-body radiation

    Sonnleitner, Matthias; Ritsch, Helmut

    2013-01-01

    Black-body radiation around hot objects induces AC Stark shifts of the energy levels of nearby atoms and molecules. These shifts are roughly proportional to the fourth power of the temperature and induce a force decaying with the third power of the distance from the object's surface. We explicitly calculate the resulting attractive black-body optical dipole force for ground state hydrogen atoms. Surprisingly this force can surpass the repulsive radiation pressure and actually pull the atoms towards the surface with a force stronger than gravity. We exemplify the dominance of the "black-body force" over gravity for hydrogen in a cloud of hot dust particles. These forces, which have been neglected to date, appear highly relevant in various astrophysical scenarios, in particular since analogous results hold for a wide class of broadband radiation sources.

  8. Kelvin probe force microscopy in liquid using electrochemical force microscopy

    Liam Collins

    2015-01-01

    Full Text Available Conventional closed loop-Kelvin probe force microscopy (KPFM has emerged as a powerful technique for probing electric and transport phenomena at the solid–gas interface. The extension of KPFM capabilities to probe electrostatic and electrochemical phenomena at the solid–liquid interface is of interest for a broad range of applications from energy storage to biological systems. However, the operation of KPFM implicitly relies on the presence of a linear lossless dielectric in the probe–sample gap, a condition which is violated for ionically-active liquids (e.g., when diffuse charge dynamics are present. Here, electrostatic and electrochemical measurements are demonstrated in ionically-active (polar isopropanol, milli-Q water and aqueous NaCl and ionically-inactive (non-polar decane liquids by electrochemical force microscopy (EcFM, a multidimensional (i.e., bias- and time-resolved spectroscopy method. In the absence of mobile charges (ambient and non-polar liquids, KPFM and EcFM are both feasible, yielding comparable contact potential difference (CPD values. In ionically-active liquids, KPFM is not possible and EcFM can be used to measure the dynamic CPD and a rich spectrum of information pertaining to charge screening, ion diffusion, and electrochemical processes (e.g., Faradaic reactions. EcFM measurements conducted in isopropanol and milli-Q water over Au and highly ordered pyrolytic graphite electrodes demonstrate both sample- and solvent-dependent features. Finally, the feasibility of using EcFM as a local force-based mapping technique of material-dependent electrostatic and electrochemical response is investigated. The resultant high dimensional dataset is visualized using a purely statistical approach that does not require a priori physical models, allowing for qualitative mapping of electrostatic and electrochemical material properties at the solid–liquid interface.

  9. Kelvin probe force microscopy in liquid using electrochemical force microscopy.

    Collins, Liam; Jesse, Stephen; Kilpatrick, Jason I; Tselev, Alexander; Okatan, M Baris; Kalinin, Sergei V; Rodriguez, Brian J

    2015-01-01

    Conventional closed loop-Kelvin probe force microscopy (KPFM) has emerged as a powerful technique for probing electric and transport phenomena at the solid-gas interface. The extension of KPFM capabilities to probe electrostatic and electrochemical phenomena at the solid-liquid interface is of interest for a broad range of applications from energy storage to biological systems. However, the operation of KPFM implicitly relies on the presence of a linear lossless dielectric in the probe-sample gap, a condition which is violated for ionically-active liquids (e.g., when diffuse charge dynamics are present). Here, electrostatic and electrochemical measurements are demonstrated in ionically-active (polar isopropanol, milli-Q water and aqueous NaCl) and ionically-inactive (non-polar decane) liquids by electrochemical force microscopy (EcFM), a multidimensional (i.e., bias- and time-resolved) spectroscopy method. In the absence of mobile charges (ambient and non-polar liquids), KPFM and EcFM are both feasible, yielding comparable contact potential difference (CPD) values. In ionically-active liquids, KPFM is not possible and EcFM can be used to measure the dynamic CPD and a rich spectrum of information pertaining to charge screening, ion diffusion, and electrochemical processes (e.g., Faradaic reactions). EcFM measurements conducted in isopropanol and milli-Q water over Au and highly ordered pyrolytic graphite electrodes demonstrate both sample- and solvent-dependent features. Finally, the feasibility of using EcFM as a local force-based mapping technique of material-dependent electrostatic and electrochemical response is investigated. The resultant high dimensional dataset is visualized using a purely statistical approach that does not require a priori physical models, allowing for qualitative mapping of electrostatic and electrochemical material properties at the solid-liquid interface. PMID:25671164

  10. Lateral Casimir-Polder force with corrugated surfaces

    Dalvit, Diego A. R.; Neto, Paulo A. Maia; Lambrecht, Astrid; Reynaud, Serge

    2007-01-01

    We derive the lateral Casimir-Polder force on a ground state atom on top of a corrugated surface, up to first order in the corrugation amplitude. Our calculation is based on the scattering approach, which takes into account nonspecular reflections and polarization mixing for electromagnetic quantum fluctuations impinging on real materials. We compare our first order exact result with two commonly used approximation methods. We show that the proximity force approximation (large corrugation wav...

  11. Ground penetrating radar

    Daniels, David J

    2004-01-01

    Ground-penetrating radar has come to public attention in recent criminal investigations, but has actually been a developing and maturing remote sensing field for some time. In the light of recent expansion of the technique to a wide range of applications, the need for an up-to-date reference has become pressing. This fully revised and expanded edition of the best-selling Surface-Penetrating Radar (IEE, 1996) presents, for the non-specialist user or engineer, all the key elements of this technique, which span several disciplines including electromagnetics, geophysics and signal processing. The

  12. Common Ground and Delegation

    Dobrajska, Magdalena; Foss, Nicolai Juul; Lyngsie, Jacob

    preconditions of increasing delegation. We argue that key HR practices?namely, hiring, training and job-rotation?are associated with delegation of decision-making authority. These practices assist in the creation of shared knowledge conditions between managers and employees. In turn, such a ?common ground......-scale questionnaire survey with unique population-wide employer-employee data. We find evidence of a direct and positive influence of hiring decisions (proxied by common educational background), and the training and job rotation of employees on delegation. Moreover, we find a positive interaction between common...

  13. OOTW Force Design Tools

    Bell, R.E.; Hartley, D.S.III; Packard, S.L.

    1999-05-01

    This report documents refined requirements for tools to aid the process of force design in Operations Other Than War (OOTWs). It recommends actions for the creation of one tool and work on other tools relating to mission planning. It also identifies the governmental agencies and commands with interests in each tool, from whom should come the user advisory groups overseeing the respective tool development activities. The understanding of OOTWs and their analytical support requirements has matured to the point where action can be taken in three areas: force design, collaborative analysis, and impact analysis. While the nature of the action and the length of time before complete results can be expected depends on the area, in each case the action should begin immediately. Force design for OOTWs is not a technically difficult process. Like force design for combat operations, it is a process of matching the capabilities of forces against the specified and implied tasks of the operation, considering the constraints of logistics, transport and force availabilities. However, there is a critical difference that restricts the usefulness of combat force design tools for OOTWs: the combat tools are built to infer non-combat capability requirements from combat capability requirements and cannot reverse the direction of the inference, as is required for OOTWs. Recently, OOTWs have played a larger role in force assessment, system effectiveness and tradeoff analysis, and concept and doctrine development and analysis. In the first Quadrennial Defense Review (QDR), each of the Services created its own OOTW force design tool. Unfortunately, the tools address different parts of the problem and do not coordinate the use of competing capabilities. These tools satisfied the immediate requirements of the QDR, but do not provide a long-term cost-effective solution.

  14. Notes on forcing axioms

    Todorcevic, Stevo; Feng, Qi

    2013-01-01

    In the mathematical practice, the Baire category method is a tool for establishing the existence of a rich array of generic structures. However, in mathematics, the Baire category method is also behind a number of fundamental results such as the Open Mapping Theorem or the Banach-Steinhaus Boundedness Principle. This volume brings the Baire category method to another level of sophistication via the internal version of the set-theoretic forcing technique. It is the first systematic account of applications of the higher forcing axioms with the stress on the technique of building forcing notions

  15. Magnetic force microscopy

    Principles of the operation of the magnetic force microscope are considered. The main areas of application of magnetic force microscopy are characterised. The prospects are shown of using this method for solving problems of materials science, including the most topical problem, viz., the creation of magnetic recording media with ultrahigh recording density. Unique potentials for investigation of nanostructures using a combination of magnetic force microscopy with electron spin resonance and nuclear magnetic resonance are pointed out. Primary attention is focused on the description of experimental techniques. The bibliography includes 27 references.

  16. Quantized Casimir Force

    Tse, Wang-Kong; Macdonald, A. H.

    2012-01-01

    We investigate the Casimir effect between two-dimensional electron systems driven to the quantum Hall regime by a strong perpendicular magnetic field. In the large separation (d) limit where retardation effects are essential we find i) that the Casimir force is quantized in units of 3\\hbar c \\alpha^2/(8\\pi^2 d^4), and ii) that the force is repulsive for mirrors with same type of carrier, and attractive for mirrors with opposite types of carrier. The sign of the Casimir force is therefore elec...

  17. The Casimir effect: a force from nothing

    The attractive force between two surfaces in a vacuum - first predicted by Hendrik Casimir over 50 years ago - could affect everything from micro machines to unified theories of nature. What happens if you take two mirrors and arrange them so that they are facing each other in empty space? Your first reaction might be 'nothing at all'. In fact, both mirrors are mutually attracted to each other by the simple presence of the vacuum. This startling phenomenon was first predicted in 1948 by the Dutch theoretical physicist Hendrik Casimir while he was working at Philips Research Laboratories in Eindhoven on - of all things - colloidal solutions (see box). The phenomenon is now dubbed the Casimir effect, while the force between the mirrors is known as the Casimir force. For many years the Casimir effect was little more than a theoretical curiosity. But interest in the phenomenon has blossomed in recent years. Experimental physicists have realized that the Casimir force affects the workings of micro machined devices, while advances in instrumentation have enabled the force to be measured with ever-greater accuracy. The new enthusiasm has also been fired by fundamental physics. Many theorists have predicted the existence of 'large' extra dimensions in 10- and 11-dimensional unified field theories of the fundamental forces. These dimensions, they say, could modify classical Newtonian gravitation at sub-millimetre distances. Measuring the Casimir effect could therefore help physicists to test the validity of such radical ideas. (U.K.)

  18. The Casimir effect: a force from nothing

    Lambrecht, Astrid [Laboratoire Kastler Brossel, Universite Pierre et Marie Curie, Ecole Normale Superieure, Centre National de Recherche Scientifique, Campus Jussieu, Case 74, Paris (France)]. E-mail: lambrecht@spectro.jussieu.fr

    2002-09-01

    The attractive force between two surfaces in a vacuum - first predicted by Hendrik Casimir over 50 years ago - could affect everything from micromachines to unified theories of nature. What happens if you take two mirrors and arrange them so that they are facing each other in empty space? Your first reaction might be 'nothing at all'. In fact, both mirrors are mutually attracted to each other by the simple presence of the vacuum. This startling phenomenon was first predicted in 1948 by the Dutch theoretical physicist Hendrik Casimir while he was working at Philips Research Laboratories in Eindhoven on - of all things - colloidal solutions (see box). The phenomenon is now dubbed the Casimir effect, while the force between the mirrors is known as the Casimir force. For many years the Casimir effect was little more than a theoretical curiosity. But interest in the phenomenon has blossomed in recent years. Experimental physicists have realized that the Casimir force affects the workings of micromachined devices, while advances in instrumentation have enabled the force to be measured with ever-greater accuracy. The new enthusiasm has also been fired by fundamental physics. Many theorists have predicted the existence of 'large' extra dimensions in 10- and 11-dimensional unified field theories of the fundamental forces. These dimensions, they say, could modify classical Newtonian gravitation at sub-millimetre distances. Measuring the Casimir effect could therefore help physicists to test the validity of such radical ideas. (U.K.)

  19. The LOFT Ground Segment

    Bozzo, E; Argan, A; Barret, D; Binko, P; Brandt, S; Cavazzuti, E; Courvoisier, T; Herder, J W den; Feroci, M; Ferrigno, C; Giommi, P; Götz, D; Guy, L; Hernanz, M; Zand, J J M in't; Klochkov, D; Kuulkers, E; Motch, C; Lumb, D; Papitto, A; Pittori, C; Rohlfs, R; Santangelo, A; Schmid, C; Schwope, A D; Smith, P J; Webb, N A; Wilms, J; Zane, S

    2014-01-01

    LOFT, the Large Observatory For X-ray Timing, was one of the ESA M3 mission candidates that completed their assessment phase at the end of 2013. LOFT is equipped with two instruments, the Large Area Detector (LAD) and the Wide Field Monitor (WFM). The LAD performs pointed observations of several targets per orbit (~90 minutes), providing roughly ~80 GB of proprietary data per day (the proprietary period will be 12 months). The WFM continuously monitors about 1/3 of the sky at a time and provides data for about ~100 sources a day, resulting in a total of ~20 GB of additional telemetry. The LOFT Burst alert System additionally identifies on-board bright impulsive events (e.g., Gamma-ray Bursts, GRBs) and broadcasts the corresponding position and trigger time to the ground using a dedicated system of ~15 VHF receivers. All WFM data are planned to be made public immediately. In this contribution we summarize the planned organization of the LOFT ground segment (GS), as established in the mission Yellow Book 1 . We...

  20. LISA Pathfinder ground testing

    Guzman, Felipe; LISA Pathfinder Team

    2010-01-01

    The space-based gravitational wave observatory LISA is a joint NASA-ESA mission that requires challenging technology to ensure pure geodetic trajectories of test masses and the interferometric measurement of distance variations between them. The LISA Pathfinder mission is an ESA-launched technology demonstrator of key LISA subsystems such as spacecraft control with micronewton thrusters, test mass drag-free control, and precision laser interferometry between free-flying test masses. Ground testing of pre-flight hardware of the Gravitational Reference Sensor and Optical Metrology subsystems is currently ongoing. Studies have been carried out on very sensitive torsion pendulums that effectively reproduce a free-fall condition for the test mass within a horizontal plane in the lab, down to frequencies loop operation, demonstrating the required optical metrology sensitivity to test mass displacement. This poster presents the current status in the development and implementation of LISA Pathfinder pre-flight systems and latest results of the ongoing ground testing efforts.

  1. Ground water and energy

    1980-05-01

    In view of complex environmental/energy decisions, the Environmental Impacts Division of the Office of Technology Impacts develops analytical methods for conducting policy analyses supporting decision making. The methods development process often begins with a workshop of leading experts and specialists in the relevant disciplines and issue areas; workshop findings are subsequently utilized by OTI to form a more solid foundation for viable policies. The National Workshop on Ground Water and Energy Production was envisioned as a tool through which OTI could obtain insights, information, and methods (on environmental, economical, physical, political, legal, and social issues) to use in its analyses, models, and assessments. To accomplish this, the Workshop comprised both plenary sessions and individual working groups. The former provided opportunities for all participants to explore issues from a broad perspective, whereas the latter enabled participants to focus on the three following areas: ground water supply; conflicts and barriers to its use; and alternatives or solutions to the various issues. This report summarizes information and insights gained by the Office of Technology Impacts during the course of the Workshop. The Key Findings section summarizes the most important facts discovered during the Workshop. The three general topics that follow (Supply, Conflicts and Barriers, and Alternatives) are those described in the Core Issues statements. The statements are reflective of the recommendations and analyses prepared by the several working groups.

  2. Quantized Casimir force.

    Tse, Wang-Kong; MacDonald, A H

    2012-12-01

    We investigate the Casimir effect between two-dimensional electron systems driven to the quantum Hall regime by a strong perpendicular magnetic field. In the large-separation (d) limit where retardation effects are essential, we find (i) that the Casimir force is quantized in units of 3ħcα(2)/8π(2)d(4) and (ii) that the force is repulsive for mirrors with the same type of carrier and attractive for mirrors with opposite types of carrier. The sign of the Casimir force is therefore electrically tunable in ambipolar materials such as graphene. The Casimir force is suppressed when one mirror is a charge-neutral graphene system in a filling factor ν=0 quantum Hall state. PMID:23368242

  3. Direct SW aerosol radiative forcing over Portugal

    D. Santos

    2008-10-01

    Full Text Available In this work, the evaluation of the aerosol radiative forcing at the top of the atmosphere as well as at the surface over the south of Portugal is made, particularly in the regions of Évora (38°34' N, 7°54' W and of Cabo da Roca (38°46' N, 9°38' W, during years 2004 and 2005.

    The radiative transfer calculations, using the radiative transfer code Second Simulation of the Satellite Signal in the Solar Spectrum (6S, combine ground-based measurements, from Aerosol Robotic NETwork (AERONET, and satellite measurements, from MODerate Imaging Spectroradiometer (MODIS, to estimate the direct SW aerosol radiative forcing. The method developed to retrieve the surface spectral reflectance is also presented, based on ground-based measurements (AERONET of the aerosol optical properties combined with the satellite-measured radiances (MODIS.

    The instantaneous direct SW aerosol radiative forcing values obtained at the top of the atmosphere are, in the majority of the cases, negative, indicating a tendency for cooling the Earth at the top of the atmosphere. For Desert Dust aerosols, over the Évora land region, the average forcing efficiency is estimated to be −25 Wm−2/AOT0.55 whereas for the Cabo da Roca area, the average forcing efficiency is −46 Wm−2/AOT0.55. In the presence of Forest Fire aerosols, both from short and long distances, the average value of forcing efficiency at the top of the atmosphere over Cabo da Roca is found to be −28 Wm−2/AOT0.55 and, over Évora, −27 Wm−2/AOT0.55. For specific situations, discussed in this work, the average surface direct SW aerosol radiative forcing efficiency due to the Desert Dust aerosols, in Évora region, is −66 Wm−2/AOT0.55, whereas in Cabo da Roca region, the corresponding average value is −38 Wm−2/AOT0.55

  4. New force in nature

    We review recent experimental and theoretical work dealing with the proposed fifth force. Further analysis of the original Eotvos experiments has uncovered no challenges to our original assertion that these data evidence a correlation characteristic of the presence of a new coupling to baryon number or hypercharge. Various models suggest that the proposed fifth force could be accommodated naturally into the existing theoretical framework. 40 refs

  5. ForcePAD

    Lindemann, J.; Damkilde, Lars

    2009-01-01

    ForcePAD is a 2-dimensional finite element application that started as a concept application for finite element modeling. Over the course of 10 years the application has been evolved into an application that is used extensively in both an educational setting as well as a tool for design and engin...... engineering. In the latest version of ForcePAD an optimization module was added to enable to take advantage of topology optimization in the design process....

  6. Bow Crushing Forces

    Pedersen, Preben Terndrup

    1996-01-01

    The purpose of these notes is to present a basis for the estimation of the internal collision forces between conventinal merchant vessels and large volume offshore structures in the form of gravity-supported offshore installations and bridges crossing international shipping routes.The main emphas...... is on the presentation of impact loads on fixed offshore structures due to bow collisions. The crushing forces are determined as functions of vessels size, vessels speed, bow profile, collision angles and eccentric impacts....

  7. Strategic forces briefing

    Bing, G.; Chrzanowski, P.; May, M.; Nordyke, M.

    1989-04-06

    The Strategic Forces Briefing'' is our attempt, accomplished over the past several months, to outline and highlight the more significant strategic force issues that must be addressed in the near future. Some issues are recurrent: the need for an effective modernized Triad and a constant concern for force survivability. Some issues derive from arms control: the Strategic Arms Reduction Talks (SALT) are sufficiently advanced to set broad numerical limits on forces, but not so constraining as to preclude choices among weapon systems and deployment modes. Finally, a new administration faced with serious budgetary problems must strive for the most effective strategic forces limited dollars can buy and support. A review of strategic forces logically begins with consideration of the missions the forces are charged with. We begin the briefing with a short review of targeting policy and implementation within the constraints of available unclassified information. We then review each element of the Triad with sections on SLBMs, ICBMs, and Air-Breathing (bomber and cruise missile) systems. A short section at the end deals with the potential impact of strategic defense on offensive force planning. We consider ABM, ASAT, and air defense; but we do not attempt to address the technical issues of strategic defense per se. The final section gives a brief overview of the tritium supply problem. We conclude with a summary of recommendations that emerge from our review. The results of calculation on the effectiveness of various weapon systems as a function of cost that are presented in the briefing are by Paul Chrzanowski.

  8. Motional Casimir force

    Jaekel, Marc-Thierry; Reynaud, Serge

    2001-01-01

    We study the situation where two point like mirrors are placed in the vacuum state of a scalar field in a two-dimensional spacetime. Describing the scattering upon the mirrors by transmittivity and reflectivity functions obeying unitarity, causality and high frequency transparency conditions, we compute the fluctuations of the Casimir forces exerted upon the two motionless mirrors. We use the linear response theory to derive the motional forces exerted upon one mirror when it moves or when th...

  9. Casimir force for electrolytes

    Høye, J. S.

    2009-01-01

    The Casimir force between a pair of parallell plates filled with ionic particles is considered. We use a statistical mechanical approach and consider the classical high temperature limit. In this limit the ideal metal result with no transverse electric (TE) zero frequency mode is recovered. This result has also been obtained by Jancovici and \\v{S}amaj earlier. Our derivation differs mainly from the latter in the way the Casimir force is evaluated from the correlation function. By our approach...

  10. Friction force microscopy

    Roland Bennewitz

    2005-01-01

    Friction force microscopy (FFM) can detect lateral force variations on the atomic scale when sliding a sharp tip over a flat surface. The sliding often takes the form of a stick-slip movement with the same periodicity as the atomic lattice. Here, I discuss how the occurrence of stick-slip instabilities is related to the onset of dissipation. The velocity and load dependence of atomic friction on various materials are discussed in the light of simple classical laws of friction.

  11. On thermonuclear reaction rates

    Hans J. Haubold; Mathai, Arak Mathai

    1996-01-01

    Nuclear reactions govern major aspects of the chemical evolution of galaxies and stars. Analytic study of the reaction rates and reaction probability integrals is attempted here. Exact expressions for the reaction rates and reaction probability integrals for nuclear reactions in the cases of nonresonant, modified nonresonant, screened nonresonant and resonant cases are given. These are expressed in terms of H-functions, G-functions and in computable series forms. Computational aspects are als...

  12. Would You Believe...? One Cannot Ignore Reaction.

    Iona, Mario

    1983-01-01

    Discusses errors/misleading statements concerning the principle of action/reaction as found in two published sources. The first, focusing on the application of Newton's third law to airplane lift, is found in a college-level text. The second, related to electromagnetic forces, is found in a book providing solutions to physics problems. (JN)

  13. Ground-penetrating rada

    Thuma, W. R.

    The theory and applications of digital Ground-Penetrating Radar were discussed at a 5-day seminar held at the China University of Geosciences in Wuhan, People's Republic of China, in April. Cohosted by the Department of Applied Geophysics and Canada-China Geoscience, more than 60 senior geophysicists, engineers, technical specialists, university professors and researchers attended.Focus of the meeting was the expanded uses of the new deep-penetrating fully digital PulseEKKO, which is gaining wide acceptance around the world. Attendees showed intense interest in this new and unique technology. Applications covered were groundwater and mineral exploration; engineering, construction and toxic waste site surveying; tunnel and underground mine probing for potential geological hazards, blind ore zones, karst cavities and solution pathways; and locating buried objects such as petroleum storage tanks, unexploded bombs and archeological remains.

  14. Isospin dependence of nucleon correlations in ground-state nuclei

    Charity, R.J. [Washington University, Department of Chemistry, St. Louis, Missouri (United States); Dickhoff, W.H. [Washington University, Department of Physics, St. Louis, Missouri (United States); Sobotka, L.G. [Washington University, Department of Chemistry, St. Louis, Missouri (United States); Washington University, Department of Physics, St. Louis, Missouri (United States); Waldecker, S.J. [University of Tennessee, Department of Physics, Chattanooga, Tennessee (United States)

    2014-02-15

    The dispersive optical model (DOM) as presently implemented can investigate the isospin (nucleon asymmetry) dependence of the Hartree-Fock-like potential relevant for nucleons near the Fermi energy. Data constraints indicate that a Lane-type potential adequately describes its asymmetry dependence. Correlations beyond the mean field can also be described in this framework, but this requires an extension that treats the non-locality of the Hartree-Fock-like potential properly. The DOM has therefore been extended to properly describe ground-state properties of nuclei as a function of nucleon asymmetry in addition to standard ingredients like elastic nucleon scattering data and level structure. Predictions of nucleon correlations at larger nucleon asymmetries can then be made after data at smaller asymmetries constrain the potentials that represent the nucleon self-energy. A simple extrapolation for Sn isotopes generates predictions for increasing correlations of minority protons with increasing neutron number. Such predictions can be investigated by performing experiments with exotic beams. The predicted neutron properties for the double closed-shell {sup 132}Sn nucleus exhibit similar correlations as those in {sup 208}Pb. Future relevance of these studies for understanding the properties of all nucleons, including those with high momentum, and the role of three-body forces in nuclei are briefly discussed. Such an implementation will require a proper treatment of the non-locality of the imaginary part of the potentials and a description of high-momentum nucleons as experimentally constrained by the (e, e' p) reactions performed at Jefferson Lab. (orig.)

  15. Does Bohm's Quantum Force Have a Classical Origin?

    Lush, David C.

    2016-08-01

    In the de Broglie-Bohm formulation of quantum mechanics, the electron is stationary in the ground state of hydrogenic atoms, because the quantum force exactly cancels the Coulomb attraction of the electron to the nucleus. In this paper it is shown that classical electrodynamics similarly predicts the Coulomb force can be effectively canceled by part of the magnetic force that occurs between two similar particles each consisting of a point charge moving with circulatory motion at the speed of light. Supposition of such motion is the basis of the Zitterbewegung interpretation of quantum mechanics. The magnetic force between two luminally-circulating charges for separation large compared to their circulatory motions contains a radial inverse square law part with magnitude equal to the Coulomb force, sinusoidally modulated by the phase difference between the circulatory motions. When the particles have equal mass and their circulatory motions are aligned but out of phase, part of the magnetic force is equal but opposite the Coulomb force. This raises a possibility that the quantum force of Bohmian mechanics may be attributable to the magnetic force of classical electrodynamics. It is further shown that relative motion between the particles leads to modulation of the magnetic force with spatial period equal to the de Broglie wavelength.

  16. Cascade enzymatic reactions for efficient carbon sequestration.

    Xia, Shunxiang; Zhao, Xueyan; Frigo-Vaz, Benjamin; Zheng, Wenyun; Kim, Jungbae; Wang, Ping

    2015-04-01

    Thermochemical processes developed for carbon capture and storage (CCS) offer high carbon capture capacities, but are generally hampered by low energy efficiency. Reversible cascade enzyme reactions are examined in this work for energy-efficient carbon sequestration. By integrating the reactions of two key enzymes of RTCA cycle, isocitrate dehydrogenase and aconitase, we demonstrate that intensified carbon capture can be realized through such cascade enzymatic reactions. Experiments show that enhanced thermodynamic driving force for carbon conversion can be attained via pH control under ambient conditions, and that the cascade reactions have the potential to capture 0.5 mol carbon at pH 6 for each mole of substrate applied. Overall it manifests that the carbon capture capacity of biocatalytic reactions, in addition to be energy efficient, can also be ultimately intensified to approach those realized with chemical absorbents such as MEA. PMID:25708541

  17. Polynomial force approximations and multifrequency atomic force microscopy

    Daniel Platz; Daniel Forchheimer; Tholén, Erik A; David B. Haviland

    2013-01-01

    We present polynomial force reconstruction from experimental intermodulation atomic force microscopy (ImAFM) data. We study the tip–surface force during a slow surface approach and compare the results with amplitude-dependence force spectroscopy (ADFS). Based on polynomial force reconstruction we generate high-resolution surface-property maps of polymer blend samples. The polynomial method is described as a special example of a more general approximative force reconstruction, where the aim is...

  18. Forced ventilation increases variability of isometric finger forces

    Li, Sheng; Yasuda, Nobuo

    2006-01-01

    The study aimed to assess the effects of forced ventilation on variability of the index finger force at the submaximal levels. Fourteen (6 men, 8 women) healthy subjects were instructed to perform self-initiated forced inspiration and forced expiration, the Valsalva maneuver and normal breathing while sustaining 15%, 30%, and 45% of maximal voluntary contraction (MVC) by the index finger. Standard deviation (S.D.) of finger forces increased significantly with the level of force. At each level...

  19. Wind-induced ground motion

    Naderyan, Vahid; Hickey, Craig J.; Raspet, Richard

    2016-02-01

    Wind noise is a problem in seismic surveys and can mask the seismic signals at low frequency. This research investigates ground motions caused by wind pressure and shear stress perturbations on the ground surface. A prediction of the ground displacement spectra using the measured ground properties and predicted pressure and shear stress at the ground surface is developed. Field measurements are conducted at a site having a flat terrain and low ambient seismic noise. Triaxial geophones are deployed at different depths to study the wind-induced ground vibrations as a function of depth and wind velocity. Comparison of the predicted to the measured wind-induced ground displacement spectra shows good agreement for the vertical component but significant underprediction for the horizontal components. To validate the theoretical model, a test experiment is designed to exert controlled normal pressure and shear stress on the ground using a vertical and a horizontal mass-spring apparatus. This experiment verifies the linear elastic rheology and the quasi-static displacements assumptions of the model. The results indicate that the existing surface shear stress models significantly underestimate the wind shear stress at the ground surface and the amplitude of the fluctuation shear stress must be of the same order of magnitude as the normal pressure. Measurement results show that mounting the geophones flush with the ground provides a significant reduction in wind noise on all three components of the geophone. Further reduction in wind noise with depth of burial is small for depths up to 40 cm.

  20. The Rotational Spectrum and Anharmonic Force Field of Chlorine Dioxide, OClO

    Muller, Holger S. P.; Sorensen, G.; Birk, Manfred; Friedl, Randy R.

    1997-01-01

    The ground state rotational and quartic centrifugal distortion constants, their vibrational changes, and the sextic centrifugal distortion constants were used in a calculation of the quartic force field together with data from infrared studies.

  1. THE PLACE OF THE FORCED LIQUIDATION OF LEGAL ENTITIES IN THE SYSTEM OF CIVIL LIABILITY

    Dmitriy Scheglov

    2015-01-01

    The definition of forced liquidation of the legal entity, the study of existing scientific approaches to the definition of the concept, an analysis of the legal entity attributes classification of legal entities, depending on the grounds for compulsory liquidation.

  2. Ship Grounding on Rock - I. Theory

    Simonsen, Bo Cerup

    1997-01-01

    This paper presents a set of analytical expressions which can be used to calculate the reaction force on a ship bottom deformed by a conical rock with a rounded tip. Closed form solutions are given for the resistance of inner and outer bottom plating, longitudinal stiffeners, girders and bulkheads...... and transverse frames, floors and bulkheads. The expressions are derived by use of an energy method or a type of 'upper bound' method which rigorously takes into account the effects of large plastic deformations, friction and fracture. A high level of generality for the methodology has been obtained...

  3. Experimental investigation on tip vortices and aerodynamics of a wing with ground effect

    Ruimin; Sun; Daichin

    2011-01-01

    The tip vortices and aerodynamics of a NACA0012 wing in the vicinity of the ground were studied in a wind tunnel.The wing tip vortex structures and lift/drag forces were measured by a seven-hole probe and a force balance,respectively.The evolution of the flow structures and aerodynamics with a ground height were analyzed.The vorticity of tip vortices was found to reduce with the decreasing of the ground height,and the position of vortex-core moved gradually to the outboard of the wing tip.Therefore,the d...

  4. Railway ground vibrations induced by wheel and rail singular defects

    Kouroussis, Georges; Connolly, David P.; Alexandrou, Georgios; Vogiatzis, Konstantinos

    2015-10-01

    Railway local irregularities are a growing source of ground-borne vibration and can cause negative environmental impacts, particularly in urban areas. Therefore, this paper analyses the effect of railway track singular defects (discontinuities) on ground vibration generation and propagation. A vehicle/track/soil numerical railway model is presented, capable of accurately predicting vibration levels. The prediction model is composed of a multibody vehicle model, a flexible track model and a finite/infinite element soil model. Firstly, analysis is undertaken to assess the ability of wheel/rail contact models to accurately simulate the force generation at the wheel/rail contact, in the presence of a singular defect. It is found that, although linear contact models are sufficient for modelling ground vibration on smooth tracks, when singular defects are present higher accuracy wheel/rail models are required. Furthermore, it is found that the variation in wheel/rail force during the singular defect contact depends on the track flexibility, and thus requires a fully coupled vehicle/track/foundation model. Next, a parametric study of ground vibrations generated by singular rail and wheel defects is undertaken. Six shapes of discontinuity are modelled, representing various defect types such as transition zones, switches, crossings, rail joints and wheel flats. The vehicle is modelled as an AM96 train set and it is found that ground vibration levels are highly sensitive to defect height, length and shape.

  5. Remotely Sensed Ground Control Points

    Hummel, P.

    2016-06-01

    Accurate ground control is required to georeferenced airborne and spaceborne images. The production of ortho-photogrammetric data requires ground control that is traditionally provided as Ground Control Points (GCPs) by GNSS measurements in the field. However, it can be difficult to acquire accurate ground control points due to required turn-around time, high costs or impossible access. CompassData, Inc. a specialist in ground control, has expanded its service to deliver Remotely Sensed Ground Control Points (RSGCPs®). TerraSAR-X and TanDEM-X are two satellites with such high accuracy of their orbital positions and SAR data that RSGCPs® can be produced to a sub-meter quality depending on certain parameters and circumstances. The technology and required parameters are discussed in this paper as well as the resulting accuracies.

  6. Radiative forcing by contrails

    Meerkoetter, R.; Schumann, U. [DLR Oberpfaffenhofen, Wessling (Germany). Inst. fuer Phys. der Atmosphaere; Doelling, D.R.; Minnis, P. [National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center; Nakajima, T.; Tsushima, Y. [Tokyo Univ. (Japan). Center for Climate System Research

    1999-08-01

    A parametric study of the instantaneous radiative impact of contrails is presented using three different radiative transfer models for a series of model atmospheres and cloud parameters. Contrails are treated as geometrically and optically thin plane parallel homogeneous cirrus layers in a static atmosphere. The ice water content is varied as a function of ambient temperature. The model atmospheres include tropical, midlatitude, and subarctic summer and winter atmospheres. Optically thin contrails cause a positive net forcing at top of the atmosphere. At the surface the radiative forcing is negative during daytime. The forcing increases with the optical depth and the amount of contrail cover. At the top of the atmosphere, a mean contrail cover of 0.1% with average optical depth of 0.2 to 0.5 causes about 0.01 to 0.03 Wm{sup -2} daily mean instantaneous radiative forcing. Contrails cool the surface during the day and heat the surface during the night, and hence reduce the daily temperature amplitude. The net effect depends strongly on the daily variation of contrail cloud cover. The indirect radiative forcing due to particle changes in natural cirrus clouds may be of the same magnitude as the direct one due to additional cover. (orig.) 78 refs.

  7. Radiative forcing by contrails

    R. Meerkötter

    Full Text Available A parametric study of the instantaneous radiative impact of contrails is presented using three different radiative transfer models for a series of model atmospheres and cloud parameters. Contrails are treated as geometrically and optically thin plane parallel homogeneous cirrus layers in a static atmosphere. The ice water content is varied as a function of ambient temperature. The model atmospheres include tropical, mid-latitude, and subarctic summer and winter atmospheres. Optically thin contrails cause a positive net forcing at top of the atmosphere. At the surface the radiative forcing is negative during daytime. The forcing increases with the optical depth and the amount of contrail cover. At the top of the atmosphere, a mean contrail cover of 0.1% with average optical depth of 0.2 to 0.5 causes about 0.01 to 0.03 Wm-2 daily mean instantaneous radiative forcing. Contrails cool the surface during the day and heat the surface during the night, and hence reduce the daily temperature amplitude. The net effect depends strongly on the daily variation of contrail cloud cover. The indirect radiative forcing due to particle changes in natural cirrus clouds may be of the same magnitude as the direct one due to additional cover.

    Key words. Atmospheric composition and structure (aerosols and particles · Meteorology and atmospheric dynamics (climatology · radiative processes

  8. Some Interoperability Issues for Computer-Generated Forces: The Theoretical Chasm between Entity-Level and Aggregated-Force Combat Simulations

    Taylor, James G.; Olwell, David H.

    2002-01-01

    CGF Computer Generated Forces and Behavioral Representation This paper presents two important interoperability issues for computer-generated forces. The first is fundamental and concerns the inconsistent representation of interfiring times of direct-fire weapons in ground combat in entity-level (i.e. discrete-event) and aggregated-force (with attrition modeled by Lanchester-type equations) combat simulations. The second is behavioral and again concerns inconsistent representation ...

  9. Confusion around the tidal force and the centrifugal force

    Matsuda, Takuya; Boffin, Henri M J

    2015-01-01

    We discuss the tidal force, whose notion is sometimes misunderstood in the public domain literature. We discuss the tidal force exerted by a secondary point mass on an extended primary body such as the Earth. The tidal force arises because the gravitational force exerted on the extended body by the secondary mass is not uniform across the primary. In the derivation of the tidal force, the non-uniformity of the gravity is essential, and inertial forces such as the centrifugal force are not needed. Nevertheless, it is often asserted that the tidal force can be explained by the centrifugal force. If we literally take into account the centrifugal force, it would mislead us. We therefore also discuss the proper treatment of the centrifugal force.

  10. The Electronic Flux in Chemical Reactions. Insights on the Mechanism of the Maillard Reaction

    Flores, Patricio; Gutiérrez-Oliva, Soledad; Herrera, Bárbara; Silva, Eduardo; Toro-Labbé, Alejandro

    2007-11-01

    The electronic transfer that occurs during a chemical process is analysed in term of a new concept, the electronic flux, that allows characterizing the regions along the reaction coordinate where electron transfer is actually taking place. The electron flux is quantified through the variation of the electronic chemical potential with respect to the reaction coordinate and is used, together with the reaction force, to shed light on reaction mechanism of the Schiff base formation in the Maillard reaction. By partitioning the reaction coordinate in regions in which different process might be taking place, electronic reordering associated to polarization and transfer has been identified and found to be localized at specific transition state regions where most bond forming and breaking occur.

  11. Ground duct ventilation in greenhouses

    Riera Sayol, Guiu

    2014-01-01

    A greenhouse climate control system is simulated in MATLAB and Simulink. The model calculates for every 20 minutes the temperatures and energy consumption over a whole year. Ground ducts are used in order to save energy which is stored in the ground when there is an excess of heat during the day. This energy is used when the temperature is not high enough, generally in the early morning. Additionally, the ground ducts reduce the usage of windows, due to better dehumidification and...

  12. Measurement of ground water flow

    The borehole methods developed by the authors to determine the filtering rate and flow direction of ground water were used in 11 investigational fields. The work mainly took place in cooperation with scientific institutions, authorities and communal societies and dealt with the problems of ground water extraction, environmental protection, and engineering geology. In about 160 ground water borehols, approximately 3600 borehole meters were measured altogether. (orig./HK)

  13. Ground-water travel time

    The Containment and Isolation Working Group considered issues related to the postclosure behavior of repositories in crystalline rock. This working group was further divided into subgroups to consider the progress since the 1978 GAIN Symposium and identify research needs in the individual areas of regional ground-water flow, ground-water travel time, fractional release, and cumulative release. The analysis and findings of the Ground-Water Travel Time Subgroup are presented

  14. Improving the optomechanical entanglement and cooling by photothermal force

    Abdi, Mehdi

    2012-01-01

    Cooling and Entanglement in optomechanical systems coupled through radiation pressure and photothermal force is studied. To develop the photothermal model, we derive an expression for deformation constant of the force. Exploiting linearized quantum Langevin equations we investigate dynamics of such systems. According to our analysis, in addition to separate action of radiation pressure and photothermal force, their cross correlation effect plays an important role in dynamics of the system. We also achieve an exact relation for the phonon number of the mechanical resonator in such systems, and then we derive an analytical expression for it at weak coupling limit. At strong coupling regime, we show that utilizing the photothermal pressure makes the ground state cooling more approachable. The effect of photothermal force on the optomechanical entanglement is investigated in detail. According to our exact numerical and approximate analytical studies, even though the photothermal force is naturally a dissipative f...

  15. Integrating Multiple Space Ground Sensors to Track Volcanic Activity

    Chien, Steve; Davies, Ashley; Doubleday, Joshua; Tran, Daniel; Jones, Samuel; Kjartansson, Einar; Thorsteinsson, Hrobjartur; Vogfjord, Kristin; Guomundsson, Magnus; Thordarson, Thor; Mandl, Daniel

    2011-01-01

    Volcanic activity can occur with little or no warning. Increasing numbers of space borne assets can enable coordinated measurements of volcanic events to enhance both scientific study and hazard response. We describe the use of space and ground measurements to target further measurements as part of a worldwide volcano monitoring system. We utilize a number of alert systems including the MODVOLC, GOESVOLC, US Air Force Weather Advisory, and Volcanic Ash Advisory Center (VAAC) alert systems. Additionally we use in-situ data from ground instrumentation at a number of volcanic sites, including Iceland.

  16. The Glyoxal Clock Reaction

    Ealy, Julie B.; Negron, Alexandra Rodriguez; Stephens, Jessica; Stauffer, Rebecca; Furrow, Stanley D.

    2007-01-01

    Research on the glyoxal clock reaction has led to adaptation of the clock reaction to a general chemistry experiment. This particular reaction is just one of many that used formaldehyde in the past. The kinetics of the glyoxal clock makes the reaction suitable as a general chemistry lab using a Calculator Based Laboratory (CBL) or a LabPro. The…

  17. From Chemical Forces to Chemical Rates: A Historical/Philosophical Foundation for the Teaching of Chemical Equilibrium

    Quílez, Juan

    2009-09-01

    With this paper, our main aim is to contribute to the realisation of the chemical reactivity concept, tracing the historical evolution of the concept of chemical affinity that eventually supported the concept of chemical equilibrium. We will concentrate on searching for the theoretical grounds of three key chemical equilibrium ideas: ‚incomplete reaction’, ‚reversibility’ and ‚dynamics’. In addition, the paper aims to promote teachers’ philosophical/historical chemical knowledge. The starting point of this historical reconstruction will be the state of the art in the construction of the first affinity tables, based on the concept of elective affinities, during the 18th century. Berthollet reworked this idea, considering that the amount of the substances involved in a reaction was a key factor accounting for the chemical forces. Guldberg and Waage attempted to measure those forces, formulating the first affinity mathematical equations. Afterwards, the first ideas providing a molecular interpretation of the macroscopic properties of equilibrium reactions are presented. Eventually, theoretical chemists integrated previous findings into a new field: thermodynamics. This historical approach may serve as a base for an appropriate sequencing of the teaching and learning of chemical equilibrium. Hence, this paper tries to go beyond the simple development of teachers’ conceptions of the nature of chemistry, for it gives suggestions about how teachers may translate such understandings into classroom practice.

  18. On the unsteady motion and stability of a heaving airfoil in ground effect

    Juan Molina; Xin Zhang; David Angland

    2011-01-01

    This study explores the fluid mechanics and force generation capabilities of an inverted heaving airfoil placed close to a moving ground using a URANS solver with the Spalart-Allmaras turbulence model. By varying the mean ground clearance and motion frequency of the airfoil, it was possible to construct a frequency-height diagram of the various forces acting on the airfoil. The ground was found to enhance the downforce and reduce the drag with respect to freestream. The unsteady motion induces hysteresis in the forces' behaviour. At moderate ground clearance, the hysteresis increases with frequency and the airfoil loses energy to the flow, resulting in a stabilizing motion. By analogy with a pitching motion, the airfoil stalls in close proximity to the ground. At low frequencies, the motion is unstable and could lead to stall flutter. A stall flutter analysis was undertaken. At higher frequencies, inviscid effects overcome the large separation and the motion becomes stable. Forced trailing edge vortex shedding appears at high frequencies. The shedding mechanism seems to be independent of ground proximity.However, the wake is altered at low heights as a result of an interaction between the vortices and the ground.

  19. Burial Ground Expansion Hydrogeologic Characterization

    Gaughan , T.F.

    1999-02-26

    Sirrine Environmental Consultants provided technical oversight of the installation of eighteen groundwater monitoring wells and six exploratory borings around the location of the Burial Ground Expansion.

  20. Unification of fundamental forces

    Abdus Salam, a Fellow of St. John's College, Cambridge, provides an accessible overview of modern particle physics and the quest for the unification of the fundamental forces, the electromagnetic, strong nuclear weak nuclear and gravitational. A major theme of the lecture is the way in which the theoretical physicists approach the task of imposing orders on a seemingly chaotic universe. A secondary theme is that the electroweak force is most likely to be the force of life. The theme of the philosophy behind the work of theorists is continued in two additional lectures by Werner Heisenberg and Paul Dirac which give fascinating insights into the modus operandi and work of two of the founders of quantum mechanics. (author)

  1. Bi-Force

    Sun, Peng; Speicher, Nora K; Röttger, Richard;

    2014-01-01

    The explosion of the biological data has dramatically reformed today's biological research. The need to integrate and analyze high-dimensional biological data on a large scale is driving the development of novel bioinformatics approaches. Biclustering, also known as 'simultaneous clustering' or 'co......-clustering', has been successfully utilized to discover local patterns in gene expression data and similar biomedical data types. Here, we contribute a new heuristic: 'Bi-Force'. It is based on the weighted bicluster editing model, to perform biclustering on arbitrary sets of biological entities, given any kind of...... pairwise similarities. We first evaluated the power of Bi-Force to solve dedicated bicluster editing problems by comparing Bi-Force with two existing algorithms in the BiCluE software package. We then followed a biclustering evaluation protocol in a recent review paper from Eren et al. (2013) (A...

  2. Forcing for mathematicians

    Weaver, Nik

    2014-01-01

    Ever since Paul Cohen's spectacular use of the forcing concept to prove the independence of the continuum hypothesis from the standard axioms of set theory, forcing has been seen by the general mathematical community as a subject of great intrinsic interest but one that is technically so forbidding that it is only accessible to specialists. In the past decade, a series of remarkable solutions to long-standing problems in C*-algebra using set-theoretic methods, many achieved by the author and his collaborators, have generated new interest in this subject. This is the first book aimed at explain

  3. Friction force microscopy

    Roland Bennewitz

    2005-05-01

    Full Text Available Friction force microscopy (FFM can detect lateral force variations on the atomic scale when sliding a sharp tip over a flat surface. The sliding often takes the form of a stick-slip movement with the same periodicity as the atomic lattice. Here, I discuss how the occurrence of stick-slip instabilities is related to the onset of dissipation. The velocity and load dependence of atomic friction on various materials are discussed in the light of simple classical laws of friction.

  4. Force-Free Foliations

    Compère, Geoffrey; Lupsasca, Alexandru

    2016-01-01

    Electromagnetic field configurations with vanishing Lorentz force density are known as force-free and appear in terrestrial, space, and astrophysical plasmas. We explore a general method for finding such configurations based on formulating equations for the field lines rather than the field itself. The basic object becomes a foliation of spacetime or, in the stationary axisymmetric case, of the half-plane. We use this approach to find some new stationary and axisymmetric solutions, one of which could represent a rotating plasma vortex near a magnetic null point.

  5. Nonlinear vibration isolator with adjustable restoring force

    Araki, Yoshikazu; Asai, Takehiko; Kimura, Kosuke; Maezawa, Kosei; Masui, Takeshi

    2013-11-01

    This paper presents a vertical quasi-zero stiffness (QZS) vibration isolator with a mechanism for adjusting restoring force. QZS vibration isolators have high initial stiffness and QZS around the static equilibrium position. This way, excessive deformation due to self-weight can be avoided while having enough vibration reduction capability to dynamic excitations. One of the main issues left for QZS vibration isolators is the difficulty in keeping the vibration reduction capability when the vibration isolated object is replaced. In such a case, adjustment of its restoring force becomes necessary in accordance with the self-weight of the newly placed vibration isolated object. This paper attempts to address this issue by proposing a mechanism that enables quick and easy adjustment of the restoring force of a QZS vibration isolator. The proposed mechanism consists of cranks and a screw jack. With the present mechanism, the restoring force provided by horizontally placed springs can be converted into the vertical restoring force of the vibration isolator. In the conversion, the vertical resisting force can be adjusted simply by applying and removing torque to the screw jack to change and hold the angle of inclined bars placed in the cranks. In this study, a prototype of a class of QZS vibration isolator having the proposed mechanism is produced. Shaking table tests are performed to demonstrate the efficacy of the present mechanism, where the produced prototype is subjected to various sinusoidal and earthquake ground motions. It is demonstrated through the shaking table tests that the produced prototype can reduce the response acceleration within the same tolerance even when the mass of the vibration isolated object is changed.

  6. Practice Gaps: Drug Reactions.

    Wolverton, Stephen E

    2016-07-01

    The term "drug reactions" is relevant to dermatology in three categories of reactions: cutaneous drug reactions without systemic features, cutaneous drug reactions with systemic features, and systemic drugs prescribed by the dermatologist with systematic adverse effects. This article uses examples from each of these categories to illustrate several important principles central to drug reaction diagnosis and management. The information presented will help clinicians attain the highest possible level of certainty before making clinical decisions. PMID:27363888

  7. AN EXCAVATION FORCE CALCULATIONS AND APPLICATIONS: AN ANALYTICAL APPROACH

    BHARGAV J. GADHVI

    2011-05-01

    Full Text Available A better tool design in the excavation process has been always a challenging task for the engineers. A poorly designed tool always results in poor excavation of the ground, higher wear of the tool, wastage of the time, and power, and thus reducing the overall productivity of the excavation operation. But proper understanding of the soil mechanics in context of the soil cutting process may help in a better tool design. Moreover; in designing the control system for an excavator requires the dynamic model of an excavator, and it requires in turn the resistive forces offered by the ground on the bucket. The excavation forces necessary to cut the soil by the excavator bucket have been analyzed in this paper to improve the design of the bucket teeth, the leap plate of the bucket,and the side cutting plates. The method used for calculating the excavation force is based on 2D analytical soiltool interaction models.

  8. Effect of sprung (suspended) floor on lower extremity stiffness during a force-returning ballet jump.

    Hackney, James; Brummel, Sara; Becker, Dana; Selbo, Aubrey; Koons, Sandra; Stewart, Meredith

    2011-12-01

    Our objective in this study was to compare stiffness of bilateral lower extremities (LEs) in ballet dancers performing sauté on a low-stiffness "sprung floor" to that during the same movement on a high-stiffness floor (wood on concrete). LE stiffness was calculated as the ratio of vertical ground reaction force (in kN) to compression of the lower limb (in meters). Seven female dancers were measured for five repetitions each at the point of maximum leg compression while performing sauté on both of the surfaces, such that 43 ms of data were represented for each trial. The stiffness of bilateral LEs at the point of maximum compression was higher by a mean difference score of 2.48 ± 2.20 kN/m on the low-stiffness floor compared to a high-stiffness floor. Paired t-test analysis of the difference scores yielded a one-tailed probability of 0.012. This effect was seen in six out of seven participants (one participant showed no difference between floor conditions). The finding of increased stiffness of the LEs in the sprung floor condition suggests that some of the force of landing the jump was absorbed by the surface, and therefore did not need to be absorbed by the participants' LEs themselves. This in turn implies that a sprung dance floor may help to prevent dance-related injuries. PMID:22211195

  9. Feature Selection and Predictors of Falls with Foot Force Sensors Using KNN-Based Algorithms

    Shengyun Liang

    2015-11-01

    Full Text Available The aging process may lead to the degradation of lower extremity function in the elderly population, which can restrict their daily quality of life and gradually increase the fall risk. We aimed to determine whether objective measures of physical function could predict subsequent falls. Ground reaction force (GRF data, which was quantified by sample entropy, was collected by foot force sensors. Thirty eight subjects (23 fallers and 15 non-fallers participated in functional movement tests, including walking and sit-to-stand (STS. A feature selection algorithm was used to select relevant features to classify the elderly into two groups: at risk and not at risk of falling down, for three KNN-based classifiers: local mean-based k-nearest neighbor (LMKNN, pseudo nearest neighbor (PNN, local mean pseudo nearest neighbor (LMPNN classification. We compared classification performances, and achieved the best results with LMPNN, with sensitivity, specificity and accuracy all 100%. Moreover, a subset of GRFs was significantly different between the two groups via Wilcoxon rank sum test, which is compatible with the classification results. This method could potentially be used by non-experts to monitor balance and the risk of falling down in the elderly population.

  10. Radiative Forcing of Climate Change

    Ramaswamy, V.; Boucher, Olivier; Haigh, J.; Hauglustaine, D.; Haywood, J.; Myhre, G.; Nakajima, Takahito; Shi, Guangyu; Solomon, S.; Betts, Robert E.; Charlson, R.; Chuang, C. C.; Daniel, J. S.; Del Genio, Anthony D.; Feichter, J.; Fuglestvedt, J.; Forster, P. M.; Ghan, Steven J.; Jones, A.; Kiehl, J. T.; Koch, D.; Land, C.; Lean, J.; Lohmann, Ulrike; Minschwaner, K.; Penner, Joyce E.; Roberts, D. L.; Rodhe, H.; Roelofs, G.-J.; Rotstayn, Leon D.; Schneider, T. L.; Schumann, U.; Schwartz, Stephen E.; Schwartzkopf, M. D.; Shine, K. P.; Smith, Steven J.; Stevenson, D. S.; Stordal, F.; Tegen, I.; van Dorland, R.; Zhang, Y.; Srinivasan, J.; Joos, Fortunat

    2001-10-01

    Chapter 6 of the IPCC Third Assessment Report Climate Change 2001: The Scientific Basis. Sections include: Executive Summary 6.1 Radiative Forcing 6.2 Forcing-Response Relationship 6.3 Well-Mixed Greenhouse Gases 6.4 Stratospheric Ozone 6.5 Radiative Forcing By Tropospheric Ozone 6.6 Indirect Forcings due to Chemistry 6.7 The Direct Radiative Forcing of Tropospheric Aerosols 6.8 The Indirect Radiative Forcing of Tropospheric Aerosols 6.9 Stratospheric Aerosols 6.10 Land-use Change (Surface Albedo Effect) 6.11 Solar Forcing of Climate 6.12 Global Warming Potentials hydrocarbons 6.13 Global Mean Radiative Forcings 6.14 The Geographical Distribution of the Radiative Forcings 6.15 Time Evolution of Radiative Forcings Appendix 6.1 Elements of Radiative Forcing Concept References.

  11. Confusion around the tidal force and the centrifugal force

    Matsuda, Takuya; Isaka, Hiromu; Boffin, Henri M. J.

    2015-01-01

    We discuss the tidal force, whose notion is sometimes misunderstood in the public domain literature. We discuss the tidal force exerted by a secondary point mass on an extended primary body such as the Earth. The tidal force arises because the gravitational force exerted on the extended body by the secondary mass is not uniform across the primary. In the derivation of the tidal force, the non-uniformity of the gravity is essential, and inertial forces such as the centrifugal force are not nee...

  12. Fluctuations of the Casimir-Polder force between an atom and a conducting wall

    We consider quantum fluctuations of the Casimir-Polder force between a neutral atom and a perfectly conducting wall in the ground state of the system. In order to obtain the atom-wall force fluctuation we first define an operator directly associated with the force experienced by the atom considered as a polarizable body in an electromagnetic field and we use a time-averaged force operator in order to avoid ultraviolet divergences appearing in the fluctuation of the force. This time-averaged force operator takes into account that any measurement involves a finite time. We also calculate the Casimir-Polder force fluctuation for an atom between two conducting walls. Experimental observability of these Casimir-Polder force fluctuations is also discussed, as well as the dependence of the relative force fluctuation on the duration of the measurement

  13. Skyrme tensor force in heavy ion collisions

    Stevenson, P. D.; Suckling, E. B.; Fracasso, S.; Barton, M. C.; Umar, A. S.

    2016-05-01

    Background: It is generally acknowledged that the time-dependent Hartree-Fock (TDHF) method provides a useful foundation for a fully microscopic many-body theory of low-energy heavy ion reactions. The TDHF method is also known in nuclear physics in the small-amplitude domain, where it provides a useful description of collective states, and is based on the mean-field formalism, which has been a relatively successful approximation to the nuclear many-body problem. Currently, the TDHF theory is being widely used in the study of fusion excitation functions, fission, and deep-inelastic scattering of heavy mass systems, while providing a natural foundation for many other studies. Purpose: With the advancement of computational power it is now possible to undertake TDHF calculations without any symmetry assumptions and incorporate the major strides made by the nuclear structure community in improving the energy density functionals used in these calculations. In particular, time-odd and tensor terms in these functionals are naturally present during the dynamical evolution, while being absent or minimally important for most static calculations. The parameters of these terms are determined by the requirement of Galilean invariance or local gauge invariance but their significance for the reaction dynamics have not been fully studied. This work addresses this question with emphasis on the tensor force. Method: The full version of the Skyrme force, including terms arising only from the Skyrme tensor force, is applied to the study of collisions within a completely symmetry-unrestricted TDHF implementation. Results: We examine the effect on upper fusion thresholds with and without the tensor force terms and find an effect on the fusion threshold energy of the order several MeV. Details of the distribution of the energy within terms in the energy density functional are also discussed. Conclusions: Terms in the energy density functional linked to the tensor force can play a non

  14. Point Charge Dynamics Near a Grounded Conducting Plane

    Haglin, Kevin L.

    2010-01-01

    The classic image problem in electromagnetism involves a grounded infinite conducting plane and a point charge. The force of attraction between the point charge and the plane is identified using an equivalent-field picture of an image charge with opposite sign equidistant behind the plane resulting in a 1/{\\it r}$^{\\rm 2}$ force of attraction between the original charge and the plane. If the point charge is released from rest it will reach the plane in a time $\\tau$. This time $\\tau$ has not ...

  15. Performing Isometric Force Control in Combination with a Cognitive Task: A Multidimensional Assessment.

    Jean-Jacques Temprado

    Full Text Available We used a multidimensional approach to study isometric force control in single and dual-task conditions.Multiple measures of performance, efficiency, variability, and structural interference were calculated at low and higher force levels under single (force maintenance and dual-task (force maintenance and reaction time conditions.Reaction time and signal-to-noise ratio were larger in the dual-task conditions. They were also greater for the higher force condition, while sample entropy was lower. Perturbation analyses revealed smaller relative amplitude of downward perturbations for the higher force level.Attentional effort and efficiency are positively related when force level increases, and inversely related to entropy. These relations were presumably mediated by attentional investment. Behavioral perturbations show that attentional resources and structural interference models are not mutually exclusive to account for dual-task situation. Overall, the present study highlights the interest of a multidimensional assessment of force control.

  16. Spin-isospin selectivity in three-nucleon forces

    Mardanpour, H; Benard, R; Biegun, A; Eslami-Kalantari, M; Joulaeizadeh, L; Kalantar-Nayestanaki, N; Kiš, M; Kistryn, St; Kozela, A; Kuboki, H; Maeda, Y; Mahjour-Shafiei, M; Messchendorp, J G; Miki, K; Noji, S; Ramazani-Moghaddam-Arani, A; Sakai, H; Sasano, M; Sekiguchi, K; Stephan, E; Sworst, R; Takahashi, Y; Yako, K

    2009-01-01

    Precision data are presented for the break-up reaction, $^2{\\rm H}(\\vec p,pp)n$, within the framework of nuclear-force studies. The experiment was carried out at KVI using a polarized-proton beam of 190 MeV impinging on a liquid-deuterium target and by exploiting the detector, BINA. Some of the vector-analyzing powers are presented and compared with state-of-the-art Faddeev calculations including three-nucleon forces effect. Significant discrepancies between the data and theoretical predictions were observed for kinematical configurations which correspond to the $^2{\\rm H}(\\vec p,^2$He$)n$ channel. These results are compared to the $^2{\\rm H}(\\vec p,d)p$ reaction to test the isospin sensitivity of the present three-nucleon force models. The current modeling of two and three-nucleon forces is not sufficient to describe consistently polarization data for both isospin states.

  17. Fifth force, sixth force and all that

    In the recent literature, a few claims appeared about possible deviations from the ordinary gravitational laws (both at the terrestrial and at the galactic level). The experimental evidence does not seem to be conclusive; nor its is clear if new forces are showing up, or if we have to accept actual deviations from Newton or Einstein gravitation (in the latter case, the validity of the very Equivalence Principle might be on the stage). In such a situation, the attempts by various authors at explaining the ''new effects'' just on the basis of the ordinary theory of General Relativity (for instance, in terms of quantum gravity) can be regarded as logically instance, in terms of quantum gravity) can be regarded as logically questionable. In this pedagogically oriented paper, the problem is approached within the classical realm, by exploring whether the possible new effects can be accounted for through minimal modifications of the standard formulatiaon of General Relativity: in particular, through exploitation and extension of the role of the cosmological constant

  18. The fifth force

    We present a phenomenological description of the ''fifth force'' which focuses on the implications of the existing data from satellite and geophysical measurements of gravity, the Eoetvoes experiment, decays into hyperphotons, and the energy-dependence of the K0 - anti K0 parameters

  19. Unification of Fundamental Forces

    Salam, Abdus; Taylor, Foreword by John C.

    2005-10-01

    Foreword John C. Taylor; 1. Unification of fundamental forces Abdus Salam; 2. History unfolding: an introduction to the two 1968 lectures by W. Heisenberg and P. A. M. Dirac Abdus Salam; 3. Theory, criticism, and a philosophy Werner Heisenberg; 4. Methods in theoretical physics Paul Adrian Maurice Dirac.

  20. Separation problems and forcing

    Zapletal, Jindřich

    2013-01-01

    Roč. 13, č. 1 (2013), s. 1350002. ISSN 0219-0613 R&D Projects: GA AV ČR IAA100190902 Institutional research plan: CEZ:AV0Z10190503 Keywords : separation * set of uniqueness * forcing Subject RIV: BA - General Mathematics Impact factor: 0.364, year: 2012 http://www.worldscientific.com/doi/abs/10.1142/S0219061313500025