WorldWideScience

Sample records for bolted friction grip

  1. Experimental Studies of a Series of High Strength Friction Grip Bolted Joints

    Directory of Open Access Journals (Sweden)

    M. Budescu

    2005-01-01

    Full Text Available The performed tests intended to establish the necessary conditions for surfaces of the assemblage elements in contact with the KB, so as, by connecting them using the HSFG (High Strength Friction Grip bolts, to ensure the necessary frictional resistance. The tests have performed using 2.5mm thickness KB250 thin – walled profiles. This minimum thickness is often used for structural elements in this constructive system. The KONTIBEAM system is primarily made of two galvanized sheet profiles so denominated as “KB”, which are joined by means of steel sheets, (usually of 10 mm thickness, placed in – between them. Connecting this assembly (KB’s and connectors is done by using M20 bolts put in Ø 22 holes, which work in friction with two contact planes. The tested joints are connected by means of 8.8 class HSFG bolts. The connecting elements for tested KB’s have been manufactured with two types of prepared surfaces: (i rough (sandblasted and (ii covered with a zincamid film. The main conclusions of tests are that the bearing capacity of connections with sandblasted surface joining elements observes the norms while the bearing capacity of connections with painted – surface joining elements does not observes the norms.

  2. Vibration damping in bolted friction beam-columns

    OpenAIRE

    Bournine, H.; Wagg, D.J.; Neild, S.A.

    2011-01-01

    In this paper we examine the use of dynamic friction within a bolted structure to improve damping properties of the structure. The structure considered for this paper consists of two steel beam-columns bolted together allowing dynamic friction to occur at the interface. This paper presents an analysis of the behaviour of the structure and the effect of friction on its dynamics. It also presents an analysis of the energy dissipation in the structure by means of friction and the optimization of...

  3. Improved Friction Joint With Self-Locking Grips

    DEFF Research Database (Denmark)

    Costache, Andrei; Glejbøl, Kristian; Sivebæk, Ion Marius

    2016-01-01

    to develop asuperior dry friction grip. Experimental results are carried using a dedicated test setup, through which the test parameters can be accurately controlled. The efficiency of the grip system during pullout is superior to results obtained with flat grips. Numerical results offer an in......-depth understanding of the influence between friction, geometrical parameters,and performance, making it possible to optimize the design. Results show that this grip system offers immediate technical applications, in a variety of conditions....

  4. Finger pad friction and its role in grip and touch.

    Science.gov (United States)

    Adams, Michael J; Johnson, Simon A; Lefèvre, Philippe; Lévesque, Vincent; Hayward, Vincent; André, Thibaut; Thonnard, Jean-Louis

    2013-03-06

    Many aspects of both grip function and tactile perception depend on complex frictional interactions occurring in the contact zone of the finger pad, which is the subject of the current review. While it is well established that friction plays a crucial role in grip function, its exact contribution for discriminatory touch involving the sliding of a finger pad is more elusive. For texture discrimination, it is clear that vibrotaction plays an important role in the discriminatory mechanisms. Among other factors, friction impacts the nature of the vibrations generated by the relative movement of the fingertip skin against a probed object. Friction also has a major influence on the perceived tactile pleasantness of a surface. The contact mechanics of a finger pad is governed by the fingerprint ridges and the sweat that is exuded from pores located on these ridges. Counterintuitively, the coefficient of friction can increase by an order of magnitude in a period of tens of seconds when in contact with an impermeably smooth surface, such as glass. In contrast, the value will decrease for a porous surface, such as paper. The increase in friction is attributed to an occlusion mechanism and can be described by first-order kinetics. Surprisingly, the sensitivity of the coefficient of friction to the normal load and sliding velocity is comparatively of second order, yet these dependencies provide the main basis of theoretical models which, to-date, largely ignore the time evolution of the frictional dynamics. One well-known effect on taction is the possibility of inducing stick-slip if the friction decreases with increasing sliding velocity. Moreover, the initial slip of a finger pad occurs by the propagation of an annulus of failure from the perimeter of the contact zone and this phenomenon could be important in tactile perception and grip function.

  5. Friction between finger flexor tendons and the pulley system in the crimp grip position.

    Science.gov (United States)

    Moor, Beat K; Nagy, Ladislav; Snedeker, Jess G; Schweizer, Andreas

    2009-01-01

    Disruption of the finger flexor tendon pulleys are the most often occurring injury in rock climbers due to bowstringing of tendons during crimp grip position. The aim of this study was to quantify friction between the flexor tendons and pulleys and the influence of high load and speed of movement as a potential factor of pulley disruption. Friction between the flexor tendons and pulleys of eight human cadaver fingers was indirectly determined using an isokinetic movement device. During flexion and extension movement with rotational speed from 30 to 210 deg/s in the proximal interphalangeal joint and with load from 20 to 100 N to the flexor tendons the flexion force at the tip of the finger was measured. With 40 N loaded flexor tendons the force at the fingertip was 14.5 N (SD1.5) during extension and 12.6N (SD1.3) during flexion movement. Corresponding force difference of 12.9% and 3.77 N (SD0.6) force of friction can be calculated. Friction peaked at 85.8 degrees (SD2.05) of flexion of the proximal interphalangeal joint. Different speed of motion and load to the flexor tendons did not influence force difference other than linear. Considerable friction between flexor tendons and pulleys is apparent and therefore may have an influence on pulley injuries. Particularly during the crimp grip position where the proximal interphalangeal joint is flexed about 90 degrees shows the greatest amount of friction. However there was no change of friction during high speed motion and no other than linear increase during high load.

  6. Application of high strength plate bolts in friction grip joints | Monda ...

    African Journals Online (AJOL)

    Creep and relaxation occur after HTB tightening causing shaft tension loss and further stress redistribution in the connected components. Past research has shown that waisting the HTB shaft diameter reduces stress concentrations, shaft tension loss and increases ductility. With the further modification of making the HTB ...

  7. Continuous miner and friction bolts play key roles in Highland's move underground

    International Nuclear Information System (INIS)

    Scott, J.J.; Jackson, D.

    1977-01-01

    Exxon has added underground mining operations to the open pits at its Highland uranium mine and mill complex 60 mi northeast of Casper in the Powder River Basin and has, in the process, adopted some innovative mining techniques. A continuous shield miner is being used in conjunction with continuous ground support--thought to be the first truly successful combination of these techniques in a US uranium mine. Highland miners are also making extensive use of ''Split Sets,'' a patented friction rock bolt system invented in 1973, which has proven to be a successful cost-saving substitute for timber supports in Highland's soft, water-saturated, extremely unstable sediments. Initial mine production at Highland began in July 1972, and the mill started up the following October. Design capacity at startup was 2,000 tpd, a figure that has since been expanded to 3,000 tpd through mill modifications but without a major construction program. Current production is about 2 million lb per year of U 3 O 8

  8. Coefficient of friction of dry slash pine and southern red oak on three tension-grip facings

    Science.gov (United States)

    Truett J. Lemoine; Peter Koch

    1974-01-01

    A urethane material proved to have nine times higher static friction coefficient (0.9) than smooth steel (0.1) on radial and tangential wood surfaces pulled parallel to the grain. It is probably superior to 220-grit garnet paper or sand coatings for tension-grip facings in lumber testing machines.

  9. Simple and Reliable Method to Estimate the Fingertip Static Coefficient of Friction in Precision Grip.

    Science.gov (United States)

    Barrea, Allan; Bulens, David Cordova; Lefevre, Philippe; Thonnard, Jean-Louis

    2016-01-01

    The static coefficient of friction (µ static ) plays an important role in dexterous object manipulation. Minimal normal force (i.e., grip force) needed to avoid dropping an object is determined by the tangential force at the fingertip-object contact and the frictional properties of the skin-object contact. Although frequently assumed to be constant for all levels of normal force (NF, the force normal to the contact), µ static actually varies nonlinearly with NF and increases at low NF levels. No method is currently available to measure the relationship between µ static and NF easily. Therefore, we propose a new method allowing the simple and reliable measurement of the fingertip µ static at different NF levels, as well as an algorithm for determining µ static from measured forces and torques. Our method is based on active, back-and-forth movements of a subject's finger on the surface of a fixed six-axis force and torque sensor. µ static is computed as the ratio of the tangential to the normal force at slip onset. A negative power law captures the relationship between µ static and NF. Our method allows the continuous estimation of µ static as a function of NF during dexterous manipulation, based on the relationship between µ static and NF measured before manipulation.

  10. Phalanx force magnitude and trajectory deviation increased during power grip with an increased coefficient of friction at the hand-object interface.

    Science.gov (United States)

    Enders, Leah R; Seo, Na Jin

    2011-05-17

    This study examined the effect of friction between the hand and grip surface on a person's grip strategy and force generation capacity. Twelve young healthy adults performed power grip exertions on an instrumented vertical cylinder with the maximum and 50% of maximum efforts (far above the grip force required to hold the cylinder), while normal and shear forces at each phalanx of all five fingers in the direction orthogonal to the gravity were recorded. The cylinder surface was varied for high-friction rubber and low-friction paper coverings. An increase in surface friction by replacing the paper covering with the rubber covering resulted in 4% greater mean phalanx normal force (perpendicular to the cylinder surface) and 22% greater mean phalanx shear force in either the proximal or distal direction of the digits (pfriction with the rubber surface compared to the paper surface was associated with a 20% increase in the angular deviation of the phalanx force from the direction normal to the cylinder surface (p<0.05). This study demonstrates that people significantly changed the magnitude and direction of phalanx forces depending on the surface they gripped. Such change in the grip strategy appears to help increase grip force generation capacity. This finding suggests that a seemingly simple power grip exertion involves sensory feedback-based motor control, and that people's power grip capacity may be reduced in cases of numbness, glove use, or injuries resulting in reduced sensation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Testing of Compact Bolted Fasteners with Insulation and Friction-Enhanced Shims for NCSX

    International Nuclear Information System (INIS)

    Dudek, L.E.; Chrzanowski, J.H.; Gettelfinger, G.; Heitzenroeder, P.; Jurczynski, S.; Viola, M.; Freudenberg, K.

    2009-01-01

    The fastening of the National Compact Stellarator Experiment's (NCSX) modular coils presented a number of engineering and manufacturing challenges due to the high magnetic forces, need to control induced currents, tight tolerances and restrictive space envelope. A fastening method using high strength studs, jack nuts, insulating spacers, bushings and alumina coated shims was developed which met the requirements. A test program was conducted to verify the design. The tests included measurements of flatness of the spacers, determination of contact area, torque vs. tension of the studs and jack nuts, friction coefficient tests on the alumina and G-10 insulators, electrical tests, and tension relaxation tests due to temperature excursions from room temperature to liquid nitrogen temperatures. This paper will describe the design and the results of the test program.

  12. Stud bolt handling equipment for reactor vessel

    International Nuclear Information System (INIS)

    Bunyan, T.W.

    1989-01-01

    Reactor vessel stud bolt handling equipment includes means for transferring a stud bolt to a carrier from a parking station, or vice versa. Preferably a number of stud bolts are handled simultaneously. The transfer means may include cross arms rotatable about extendable columns, and the equipment is mounted on a mobile base for movement into and out of position. Each carrier comprises a tubular socket and an expandable sleeve to grip a stud bolt. (author)

  13. Bolting applications

    International Nuclear Information System (INIS)

    Czajkowski, C.J.

    1984-05-01

    An investigation of bolting practices specific to the nuclear industry was performed. The report covered a large spectrum of topics e.g., bolts embedded in concrete, specifications, inspection of bolting, both at receipt and inservice. Plots of preload versus yield strength for different bolting materials in different environments are presented as well as information relative to the stress corrosion cracking resistance of the more recent reactor internals bolting materials A286 and Inconel X-750. Part of the report contains input by Standard Pressed Steel Inc. (a bolting consultant) relative to bolting standards, cottering methods and potential areas for bolting improvement

  14. Contribution of Clearance Holes to Semi-rigid Effects of Bolted Joints

    Science.gov (United States)

    Baiburin, A. Kh; Semenov, K. O.

    2017-11-01

    This paper presents an analysis of semi-rigid effects of bolted joints occurring due to clearance holes and manufacturing tolerances at temporary fixing and the exploitation stages. The manufacturing requirements of SP 53-101-98 ‘Production and Quality Control of Steel Structures’ and GOST 23118-2012 ‘Building Steel Structures. General Specifications’ are used for calculations. Friction-grip joints with high-strength bolts are considered as well as joints with ordinary structural bolts. Different permissible assembling technologies are reviewed to account a non-linear behaviour of the joint at temporary fixing and during the operational stage. The recommendations were developed for the scheduling of mounting works which can provide convergence between the design of a whole building and the consequential calculations of mounting schemes.

  15. Study of the effects of the hand grip and finger strengths on the friction and petrissage - the massage manipulations - of the students who take massage courses: Kütahya City example

    Directory of Open Access Journals (Sweden)

    Erzeybek Mustafa Said

    2016-01-01

    Full Text Available In this research, the effect of the hand grip and finger strengths on the power development between the friction and petrissage techniques - the massage manipulations - have been studied. To the study that has been structured as a single group pretest/post test, 36 healthy males who are the students of the University of Dumlupınar, Academy of Physical Education and Sports and who take massage courses (age = 19.72 ± 1.56 years (average ± Sd have been included. The practical massage course has continued for 12 weeks, two days a week for a total of one hour and the hand grip strength of both hands (right hand grip strength = RHG, left hand grip strength = LHG and the grip strength of both fingers (right finger strength = RF, left finger strength = LF have been recorded at the beginning. For the measurements carried out before and later of the study with regard to the hand grip strength, a Takkei branded hand dynamometer and with regard to the finger grip strength a (baseline branded pinch meter have been used. All measurements have been repeated twice and for the analysis, the average values obtained from two deads have been used. For statistical analysis, with regard to the changes in the pre test-post test finger strength and hand grip strength, paired-samples t test has been used. The significance limit has been defined as p0.05. It is possible to report that massaging regularly with both hands is efficient for the development of the finger and hand grip strengths; especially, with regard to the friction (circular movements that are generally carried out with fingers and petrissage (kneading that is generally carried out with the palm techniques.

  16. A Strain-Based Method to Detect Tires’ Loss of Grip and Estimate Lateral Friction Coefficient from Experimental Data by Fuzzy Logic for Intelligent Tire Development

    Directory of Open Access Journals (Sweden)

    Jorge Yunta

    2018-02-01

    Full Text Available Tires are a key sub-system of vehicles that have a big responsibility for comfort, fuel consumption and traffic safety. However, current tires are just passive rubber elements which do not contribute actively to improve the driving experience or vehicle safety. The lack of information from the tire during driving gives cause for developing an intelligent tire. Therefore, the aim of the intelligent tire is to monitor tire working conditions in real-time, providing useful information to other systems and becoming an active system. In this paper, tire tread deformation is measured to provide a strong experimental base with different experiments and test results by means of a tire fitted with sensors. Tests under different working conditions such as vertical load or slip angle have been carried out with an indoor tire test rig. The experimental data analysis shows the strong relation that exists between lateral force and the maximum tensile and compressive strain peaks when the tire is not working at the limit of grip. In the last section, an estimation system from experimental data has been developed and implemented in Simulink to show the potential of strain sensors for developing intelligent tire systems, obtaining as major results a signal to detect tire’s loss of grip and estimations of the lateral friction coefficient.

  17. A Strain-Based Method to Detect Tires' Loss of Grip and Estimate Lateral Friction Coefficient from Experimental Data by Fuzzy Logic for Intelligent Tire Development.

    Science.gov (United States)

    Yunta, Jorge; Garcia-Pozuelo, Daniel; Diaz, Vicente; Olatunbosun, Oluremi

    2018-02-06

    Tires are a key sub-system of vehicles that have a big responsibility for comfort, fuel consumption and traffic safety. However, current tires are just passive rubber elements which do not contribute actively to improve the driving experience or vehicle safety. The lack of information from the tire during driving gives cause for developing an intelligent tire. Therefore, the aim of the intelligent tire is to monitor tire working conditions in real-time, providing useful information to other systems and becoming an active system. In this paper, tire tread deformation is measured to provide a strong experimental base with different experiments and test results by means of a tire fitted with sensors. Tests under different working conditions such as vertical load or slip angle have been carried out with an indoor tire test rig. The experimental data analysis shows the strong relation that exists between lateral force and the maximum tensile and compressive strain peaks when the tire is not working at the limit of grip. In the last section, an estimation system from experimental data has been developed and implemented in Simulink to show the potential of strain sensors for developing intelligent tire systems, obtaining as major results a signal to detect tire's loss of grip and estimations of the lateral friction coefficient.

  18. Friction

    Science.gov (United States)

    Matsuo, Yoshihiro; Clarke, Daryl D.; Ozeki, Shinichi

    Friction materials such as disk pads, brake linings, and clutch facings are widely used for automotive applications. Friction materials function during braking due to frictional resistance that transforms kinetic energy into thermal energy. There has been a rudimentary evolution, from materials like leather or wood to asbestos fabric or asbestos fabric saturated with various resins such as asphalt or resin combined with pitch. These efforts were further developed by the use of woven asbestos material saturated by either rubber solution or liquid resin binder and functioned as an internal expanding brake, similar to brake lining system. The role of asbestos continued through the use of chopped asbestos saturated by rubber, but none was entirely successful due to the poor rubber heat resistance required for increased speeds and heavy gearing demands of the automobile industry. The use of phenolic resins as binder for asbestos friction materials provided the necessary thermal resistance and performance characteristics. Thus, the utility of asbestos as the main friction component, for over 100 years, has been significantly reduced in friction materials due to asbestos identity as a carcinogen. Steel and other fibrous components have displaced asbestos in disk pads. Currently, non-asbestos organics are the predominate friction material. Phenolic resins continue to be the preferred binder, and increased amounts are necessary to meet the requirements of highly functional asbestos-free disk pads for the automotive industry. With annual automobile production exceeding 70 million vehicles and additional automobile production occurring in developing countries worldwide and increasing yearly, the amount of phenolic resin for friction material is also increasing (Fig. 14.1). Fig. 14.1 Worldwide commercial vehicle production In recent years, increased fuel efficiency of passenger car is required due to the CO2 emission issue. One of the solutions to improve fuel efficiency is to

  19. GRIPS bibliography

    Energy Technology Data Exchange (ETDEWEB)

    1978-07-31

    This GRIPS (Geothermal Resources Impact Project Study) contains over 1700 references on a wide variety of subjects dealing directly or indirectly with geothermal development at the Geysers/Calistoga KGRA. (MHR)

  20. Behavior of Fiber Glass Bolts, Rock Bolts and Cable Bolts in Shear

    Science.gov (United States)

    Li, Xuwei; Aziz, Naj; Mirzaghorbanali, Ali; Nemcik, Jan

    2016-07-01

    This paper experimentally compares the shear behavior of fiber glass (FG) bolt, rock bolt (steel rebar bolt) and cable bolt for the bolt contribution to bolted concrete surface shear strength, and bolt failure mode. Two double shear apparatuses of different size were used for the study. The tensile strength, the shear strength and the deformation modulus of bolt control the shear behavior of a sheared bolted joint. Since the strength and deformation modulus of FG bolt, rock bolt and cable bolt obtained from uniaxial tensile tests are different, their shear behavior in reinforcing joints is accordingly different. Test results showed that the shear stiffness of FG bolted joints decreased gradually from the beginning to end, while the shear stiffness of joints reinforced by rock bolt and cable bolt decreased bi-linearly, which is clearly consistent with their tensile deformation modulus. The bolted joint shear stiffness was highly influenced by bolt pretension in the high stiffness stage for both rock bolt and cable bolt, but not in the low stiffness stage. The rock bolt contribution to joint shear strength standardised by the bolt tensile strength was the largest, followed by cable bolts, then FG bolts. Both the rock bolts and cable bolts tended to fail in tension, while FG bolts in shear due to their low shear strength and constant deformation modulus.

  1. Piezoelectric Bolt Breakers and Bolt Fatigue Testers

    Science.gov (United States)

    Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph; Barengoltz, Jack; Heckman, Vanessa

    2008-01-01

    A proposed family of devices for inducing fatigue in bolts in order to break the bolts would incorporate piezoelectric actuators into resonant fixtures as in ultrasonic/ sonic drills/corers and similar devices described in numerous prior NASA Tech Briefs articles. These devices were originally intended primarily for use as safer, more-reliable, more-versatile alternatives to explosive bolts heretofore used to fasten spacecraft structures that must subsequently be separated from each other quickly on command during flight. On Earth, these devices could be used for accelerated fatigue testing of bolts. Fatigue theory suggests that a bolt subjected to both a constant-amplitude dynamic (that is, oscillatory) stress and a static tensile stress below the ultimate strength of the bolt material will fail faster than will a bolt subjected to only the dynamic stress. This suggestion would be applied in a device of the proposed type. The device would be designed so that the device and the bolt to be fatigue-tested or broken would be integral parts of an assembly (see figure). The static tension in the tightened bolt would apply not only the clamping force to hold the joined structures (if any) together but also the compression necessary for proper operation of the piezoelectric actuators as parts of a resonant structural assembly. The constant-amplitude dynamic stress would be applied to the bolt by driving the piezoelectric actuators with a sinusoidal voltage at the resonance frequency of longitudinal vibration of the assembly. The amplitude of the excitation would be made large enough so that the vibration would induce fatigue in the bolt within an acceptably short time. In the spacecraft applications or in similar terrestrial structural-separation applications, devices of the proposed type would offer several advantages over explosive bolts: Unlike explosive bolts, the proposed devices would be reusable, could be tested before final use, and would not be subject to

  2. Beam to Column Timber Joints with Pretensioned Bolts

    Directory of Open Access Journals (Sweden)

    Hayashikawa T.

    2011-01-01

    Full Text Available The effects of pretension in bolts on hysteretic response of timber joints exposed to a bending had been reported by the authors, but the cyclic tests were carried out at small displacement level which might not be applicable for earthquake-resistance design. In this study, similar cyclic tests but at large displacement levels were conducted. Beam to column timber joints with steel side plates were fabricated and continuously loaded until failure. At connection, the bolts were pretension in four different magnitudes: 0 kN, 5 kN, 10 kN and 15 kN. The results showed that frictional action between the steel side plates and wood member as a result of bolt pretensioning significantly increased the (frictional hysteretic damping and the equivalent viscous damping ratio. It is obvious from the test results that the pretension force in bolts has no influence on the maximum joint resistance but decreases the joint rotational deformation.

  3. Roof bolting equipment & technology

    Energy Technology Data Exchange (ETDEWEB)

    Fiscor, S.

    2009-04-15

    Technology provides an evaluator path to improvement for roof bolting machines. Bucyrus offers three different roof bolts models for various mining conditions. The LRB-15 AR is a single-arm boiler recommended for ranges of 32 inches and above; the dual-arm RB2-52A for ranges of 42 inches and above; and the dual-arm RB2-88A for ranges of 54 inches and above. Design features are discussed in the article. Developments in roof bolting technology by Joy Mining Machinery are reported. 4 photos.

  4. Optimization of Bolt Stress

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard

    2013-01-01

    The state of stress in bolts and nuts with ISO metric thread design is examined and optimized. The assumed failure mode is fatigue so the applied preload and the load amplitude together with the stress concentrations define the connection strength. Maximum stress in the bolt is found at, the fillet...... under the head, at the thread start or at the thread root. To minimize the stress concentration shape optimization is applied....

  5. Bolting multicenter solutions

    Energy Technology Data Exchange (ETDEWEB)

    Bena, Iosif [Institut de Physique Théorique, Université Paris Saclay, CEA, CNRS, 91191 Gif-sur-Yvette Cedex (France); Bossard, Guillaume [Centre de Physique Théorique, Ecole Polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau Cedex (France); Katmadas, Stefanos; Turton, David [Institut de Physique Théorique, Université Paris Saclay, CEA, CNRS, 91191 Gif-sur-Yvette Cedex (France)

    2017-01-30

    We introduce a solvable system of equations that describes non-extremal multicenter solutions to six-dimensional ungauged supergravity coupled to tensor multiplets. The system involves a set of functions on a three-dimensional base metric. We obtain a family of non-extremal axisymmetric solutions that generalize the known multicenter extremal solutions, using a particular base metric that introduces a bolt. We analyze the conditions for regularity, and in doing so we show that this family does not include solutions that contain an extremal black hole and a smooth bolt. We determine the constraints that are necessary to obtain smooth horizonless solutions involving a bolt and an arbitrary number of Gibbons-Hawking centers.

  6. Overall bolt stress optimization

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard

    2013-01-01

    The state of stress in bolts and nuts with International Organization for Standardization metric thread design is examined and optimized. The assumed failure mode is fatigue, so the applied preload and the load amplitude together with the stress concentrations define the connection strength....... Maximum stress in the bolt is found at the fillet under the head, at the thread start, or at the thread root. To minimize the stress concentration, shape optimization is applied. Nut shape optimization also has a positive effect on the maximum stress. The optimization results show that designing a nut......, which results in a more evenly distribution of load along the engaged thread, has a limited influence on the maximum stress due to the stress concentration at the first thread root. To further reduce the maximum stress, the transition from bolt shank to the thread must be optimized. Stress reduction...

  7. A Method to Capture Macroslip at Bolted Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hopkins, Ronald Neil; Heitman, Lili Anne Akin

    2015-10-01

    Relative motion at bolted connections can occur for large shock loads as the internal shear force in the bolted connection overcomes the frictional resistive force. This macroslip in a structure dissipates energy and reduces the response of the components above the bolted connection. There is a need to be able to capture macroslip behavior in a structural dynamics model. A linear model and many nonlinear models are not able to predict marcoslip effectively. The proposed method to capture macroslip is to use the multi-body dynamics code ADAMS to model joints with 3-D contact at the bolted interfaces. This model includes both static and dynamic friction. The joints are preloaded and the pinning effect when a bolt shank impacts a through hole inside diameter is captured. Substructure representations of the components are included to account for component flexibility and dynamics. This method was applied to a simplified model of an aerospace structure and validation experiments were performed to test the adequacy of the method.

  8. Turbine casing bolts; a life assessment and bolt replacement strategy

    Energy Technology Data Exchange (ETDEWEB)

    Bulloch, J.H. [ESB, Power Generation, Dublin (Ireland)

    1998-12-31

    The present presentation describes a detailed study concerning the life assessment and replacement strategy of large turbine casing bolts in a 120 MW steam raising unit. After 122000 hours service, circa 1991/92, the Cr-Mo-V steel casing bolts, involving a total of 184 bolts, from two identical 120 MW units, termed Units 1 and 2, were examined to establish the extent of Reverse Temper Embrittlement, RTE, and creep damage suffered during service. The bolt replacement plans for the two units were as follows; Unit 1 bolts were completely replaced with new bolts while Unit 2 embrittled bolts were withdrawn from service and replaced with Non- Embrittled bolts from Unit 1; basically Unit 2 bolts were made up from a mixture of Unit 1 and 2 Non- Embrittled bolts which had been in service for 122000 hours. Remnant life assessments, concerning both embrittlement and creep damage aspects, were earned out on this series of easing bolts at service times 122000, 150000 and 200000 hours. These assessments involved the use of general embrittlement and creep damage laws which were empirically derived and concerned such parameters as microstructural grain size, bulk phosphorus content and accumulated service strain. (orig.) 7 refs.

  9. GRIP CLOUD MICROPHYSICS V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Cloud Microphysics dataset was collected during the GRIP campaign from three probes: the Cloud, Aerosol, and Precipitation Spectrometer (CAPS), the...

  10. Bolt Thread Stress Optimization

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard

    2012-01-01

    Designs of threaded fasteners are controlled by different standards, and the number of different thread definitions is large. The most commonly used thread is probably the metric ISO thread, and this design is therefore used in this paper. Thread root design controls the stress concentration factor...... of threads and therefore indirectly the bolt fatigue life. The root shape is circular, and from shape optimization for minimum stress concentration it is well known that the circular shape is seldom optimal. An axisymmetric Finite Element (FE) formulation is used to analyze the bolted connection, and a study...... is performed to establish the need for contact modeling with regard to finding the correct stress concentration factor. Optimization is performed with a simple parameterization with two design variables. Stress reduction of up to 9% is found in the optimization process, and some similarities are found...

  11. 30 CFR 75.204 - Roof bolting.

    Science.gov (United States)

    2010-07-01

    ... anchor trailing cables or used for any other purpose that could affect the tension of the bolt. Hanging... tension ranges for roof bolts as specified in the roof control plan shall maintain the integrity of the.... (4) In each roof bolting cycle, the actual torque or tension of the first tensioned roof bolt...

  12. GRIP CAMPAIGN REPORTS V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Campaign Reports dataset consists of various reports filed by scientists during the GRIP campaign which took place 8/15/2010 - 9/30/2010; however, several...

  13. Influence of the gripping fixture on the modified compact tension test results: Evaluation of the experiments on cylindrical concrete specimens

    Czech Academy of Sciences Publication Activity Database

    Holušová, T.; Lozano, M.; Canteli, A.; Komárková, T.; Kocáb, D.; Seitl, Stanislav

    2015-01-01

    Roč. 15, č. 2 (2015) ISSN 1804-4824 Institutional support: RVO:68081723 Keywords : Modified compact tension test * fracture parametr * Cementitious composites * Aramis measurement * grips Subject RIV: JL - Materials Fatigue, Friction Mechanics

  14. External Coulomb-Friction Damping For Hydrostatic Bearings

    Science.gov (United States)

    Buckmann, Paul S.

    1992-01-01

    External friction device damps vibrations of shaft and hydrostatic ring bearing in which it turns. Does not rely on wear-prone facing surfaces. Hydrostatic bearing ring clamped in radially flexing support by side plates clamped against radial surfaces by spring-loaded bolts. Plates provide friction against radial motions of shaft.

  15. Collets and friction

    Science.gov (United States)

    McIlraith, A. H.

    2005-07-01

    Conical sleeves, known as collets, have long been used for clamping sliding bodies to cylindrical columns in any desired position. Quantitative expressions for their properties are presented. Of particular interest is the ability of a collet to hold a shaft stationary against axial forces in either direction, and yet be able to release its grip with a minimum of additional force. This treatment relates the firmness of grip, the ease of release and the interface stresses to the cone angle, the coefficients of friction and the applied axial forces. The central part played by hysteresis is revealed. Experiments employing a test model give good support to the theoretical conclusions. They show that, up to the interface pressures reached, about 250 MPa, the friction between lubricated hardened steel and mild steel surfaces is independent of pressure. The strong dependence of friction on surface roughness is demonstrated. The possible adaptation of the collet test equipment to the measurement of friction at high interface pressures is touched upon. It could be a complementary alternative to the more flexible pin-on-disc method. With much larger working areas, it should have the advantages of better defined areas of contact, reduced ploughing effects and less leakage of lubricant.

  16. BOLTING OF RED BEET: PROBLEMS AND SOLUTIONS

    Directory of Open Access Journals (Sweden)

    V. I. Burenin

    2016-01-01

    Full Text Available Results of study of the collection accessions of red beet with different level of bolting resistance are presented. Nature of inheritance of this trait in progeny, and also its connection with other biological and economically valuable characters and properties is shown. Bolting resistant accessions and possibility of its use in breeding are described. The promising initial material is selected and recommended. The most rational solution of the bolting problems in the beet is the development of resistant varieties and hybrids. For this purpose, the early-spring and under-winter planting are used, as well as the seed germination at low (30C temperatures. The availability of the various initial material studied by modern methods of researches plays a key role. When the collection accessions of beet were studied in the VIR Polar branch (The Murmansk Region, the following genotypes were identified: 1 – non bolting, 2 – weak bolting (less than 10% of bolting plants, 3 – moderately bolting (10-50%, and 4 – high bolting (more than 50% of bolting plants. As a result of screening of a gene pool, the genetic sources of bolting resistance of beet were identified. At its crossing with bolting accessions the dominance of the trait «bolting» and monogenic nature of its inheritance are confirmed. For the purpose of beet breeding for bolting resistance, the symphycarpous varieties characterized by complex biological and agronomic characters (increased yield, cold tolerance, quality of production and resistance to blackleg are the most usable. The cultivars Banko from Sweden (donor, Podzimnyaya A-0474 (VNIISSOK and Polyarnaya ploskaya-249 (Polar branch VIR are recommended as a genetic sources of bolting resistance.

  17. A bolt from the blue.

    Science.gov (United States)

    Claydon, S M

    1993-10-01

    The crossbow was one of the most efficient military weapons of the Middle Ages but the development of portable firearms meant that it was eventually relegated to the museum shelf. The medieval crossbow was accurate and deadly but took some time to load because of the windlass used to wind the string, thus increasing the velocity and range of the bolt, or quarrel. By contrast, the English longbows of Crecy and Agincourt were far less accurate but could fire six arrows in the time taken to shoot one bolt and the continual raining-down of missiles proved more successful in battle than accuracy of aim. This paper describes the homicide of a young business woman outside her London flat in 1987. Today crossbow fatalities are extremely rare on both sides of the Atlantic but Dr Siva described a case of suicide in 1979 and Professor Gresham presented a case of crossbow homicide to the BAFM in June 1976.

  18. Conveyor system bolt failure analysis

    International Nuclear Information System (INIS)

    McCutcheon, S.H.; Waaser, R.E.

    1981-07-01

    The Savannah River Plant (SRP) is operated for the U.S. Department of Energy (DOE) by E.I. du Pont de Nemours and Co. Reactors at SRP are used to produce nuclear isotopes for national defense. As part of the routine operation of each of the reactors, irradiated fuel assemblies are remotely discharged from the reactor, transferred in air, and placed underwater in a Deposit and Exit (D and E) canal. The D and E conveyor transports the assemblies under the reactor room wall into the disassembly basin, where they are stored for several months before shipment to the separations areas. On August 13, 1980, a broken bolt was discovered on the D and E conveyor during a routine pre-operational inspection. The failed bolt was one of four which anchor a bearing on one of the conveyor drive shafts. All four of the bolts on the affected bearing were replaced as an immediate corrective measure and the discharge of irradiated fuel assemblies was subsequently completed without difficulty

  19. Removable Type Expansion Bolt Innovative Design

    Science.gov (United States)

    Wang, Feng-Lan; Zhang, Bo; Gao, Bo; Liu, Yan-Xin; Gao, Bo

    2016-05-01

    Expansion bolt is a kind of the most common things in our daily life. Currently, there are many kinds of expansion bolts in the market. However, they have some shortcomings that mainly contain underuse and unremovement but our innovation of design makes up for these shortcomings very well. Principle of working follows this: expansion tube is fixed outside of bolt, steel balls and expansion covers are fixed inside. Meanwhile, the steel balls have 120° with each other. When using it ,expansion cover is moved in the direction of its internal part. So the front part of expansion bolt cover is increasingly becoming big and steel halls is moved outside. Only in this way can it be fixed that steel balls make expansion tube expand. When removing them, expansion bolt is moved outside. So the front part of expansion bolt cover is gradually becoming small and steel balls moves inside, after expansion tube shrinks, we can detach them.

  20. Control of prestress levels in bolted joints

    International Nuclear Information System (INIS)

    Bartonicek, J.; Schoeckle, F.

    1992-01-01

    In many cases the quality and integrity of a bolted joint depend on an exact prestressing level. This is essential with bolted flanged joints as well as with bolted pipe clamps, which are used in piping restraints. Without measuring the resulting prestress levels, common prestressing methods of flanged joints-as the use of torque spanners- might lead to insufficient prestressing levels and to a large scatterband in prestress values. The use of hydraulic tightening method is preferable. Using hydraulic tightening methods and specially developed measurement devices, controlled mounting of bolted flanged joints is easy. Control is provided during the entire tightening process, the resulting forces can be documented on printer output. Exact prestress levels can be controlled and applied to bolted pipe clamps with a new loading and measuring device. With this device the long term behaviour of the stress levels in the bolts of pipe clamps are measured successfully without dismounting the clamps. (orig.)

  1. GRIP CLOUD MICROPHYSICS V1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set consists of data collected during the GRIP campaign from three probes: the Cloud, Aerosol, and Precipitation Spectrometer (CAPS), the Precipitation...

  2. Alternative methods to model frictional contact surfaces using NASTRAN

    Science.gov (United States)

    Hoang, Joseph

    1992-01-01

    Elongated (slotted) holes have been used extensively for the integration of equipment into Spacelab racks. In the past, this type of interface has been modeled assuming that there is not slippage between contact surfaces, or that there is no load transfer in the direction of the slot. Since the contact surfaces are bolted together, the contact friction provides a load path determined by the normal applied force (bolt preload) and the coefficient of friction. Three alternate methods that utilize spring elements, externally applied couples, and stress dependent elements are examined to model the contacted surfaces. Results of these methods are compared with results obtained from methods that use GAP elements and rigid elements.

  3. 5/8'' baffle bolt replacement

    International Nuclear Information System (INIS)

    Pinaud, T.; Grypczynski, D.

    1999-01-01

    Both Framatome Nuclear Services in France and its U.S. arm, FT1, are now equipped with baffle bolt inspection and replacement packages. These packages allow them to tackle baffle bold degradation on both two- and three-loop nuclear power plants. Framatome and FT1 together are world leaders in addressing reactor vessel internal bolting concerns

  4. Friction Joint Between Basalt-Reinforced Composite and Aluminum

    DEFF Research Database (Denmark)

    Costache, Andrei; Glejbøl, Kristian; Sivebæk, Ion Marius

    2015-01-01

    The purpose of this study was to anchor basalt-reinforced polymers in an aluminum grip using dry friction. Dry friction clamping is considered the optimal solution for post-mounting of load-bearing terminations on composite structures. A new test method is presented for characterizing...... the frictional load transfer behavior of the grip. To carry out the study, a custom-built test rig was used to examine the relation between pullout force and clamping force. The anchoring method was found to be successful. The paper presents details on the custom-built test rig, along with the use of digital...

  5. Sex difference and relationship among peak grip strength, grip ...

    African Journals Online (AJOL)

    Objective: Hand dominance is a term that describes a preference to use one hand more than the other for everyday tasks. It could be described as the phenomenon that occurs when one hand is preferred to the other for fine motor skills tasks. Hand grip strength is a physiological variable that is affected by a number of ...

  6. 46 CFR 56.25-20 - Bolting.

    Science.gov (United States)

    2010-10-01

    ... steel stud bolts must be threaded full length or, if desired, may have reduced shanks of a diameter not less than that at the root of the threads. They must have heavy semifinished hexagonal nuts in...

  7. Bolt Cutter Blade's Imprint in Toolmarks Examination.

    Science.gov (United States)

    Volkov, Nikolai; Finkelstein, Nir; Novoselsky, Yehuda; Tsach, Tsadok

    2015-11-01

    Bolt cutters are known as cutting tools which are used for cutting hard objects and materials, such as padlocks and bars. Bolt cutter blades leave their imprint on the cut objects. When receiving a cut object from a crime scene, forensic toolmarks examiners can determine whether the suspected cutting tool was used in a specific crime or not based on class characteristic marks and individual marks that the bolt cutter blades leave on the cut object. The paper presents preliminary results of a study on ten bolt cutters and suggests a quick preliminary examination-the comparison between the blade thickness and the width of the imprint left by the tool on the cut object. Based on the comparison result, if there is not a match, the examiner can eliminate the feasibility of the use of the suspected cutting tool in a specific crime. This examination simplifies and accelerates the comparison procedure. © 2015 American Academy of Forensic Sciences.

  8. Reference Values of Grip Strength, Prevalence of Low Grip Strength, and Factors Affecting Grip Strength Values in Chinese Adults.

    Science.gov (United States)

    Yu, Ruby; Ong, Sherlin; Cheung, Osbert; Leung, Jason; Woo, Jean

    2017-06-01

    The objectives of this study were to update the reference values of grip strength, to estimate the prevalence of low grip strength, and to examine the impact of different aspects of measurement protocol on grip strength values in Chinese adults. A cross-sectional survey of Chinese men (n = 714) and women (n = 4014) aged 18-102 years was undertaken in different community settings in Hong Kong. Grip strength was measured with a digital dynamometer (TKK 5401 Grip-D; Takei, Niigata, Japan). Low grip strength was defined as grip strength 2 standard deviations or more below the mean for young adults. The effects of measurement protocol on grip strength values were examined in a subsample of 45 men and women with repeated measures of grip strength taken with a hydraulic dynamometer (Baseline; Fabrication Enterprises Inc, Irvington, NY), using pair t-tests, intraclass correlation coefficient, and Bland and Altman plots. Grip strength was greater among men than among women (P values than the Baseline hydraulic dynamometer (P values were also observed when the measurement was performed with the elbow extended in a standing position, compared with that with the elbow flexed at 90° in a sitting position, using the same dynamometer (P values of grip strength and estimated the prevalence of low grip strength among Chinese adults spanning a wide age range. These findings might be useful for risk estimation and evaluation of interventions. However, grip strength measurements should be interpreted with caution, as grip strength values can be affected by type of dynamometer used, assessment posture, and elbow position. Copyright © 2017 AMDA – The Society for Post-Acute and Long-Term Care Medicine. Published by Elsevier Inc. All rights reserved.

  9. Evaluation of Many Load Tests of Passive Rock Bolts in the Czech Republic

    Directory of Open Access Journals (Sweden)

    Holý Ondřej

    2017-03-01

    Full Text Available Within the research project “FR-TI4/329 Research and development - creating an application system for the design and analysis of soil and rock anchors including the development of monitoring elements”, an extensive stage of field load tests of rock bolts was carried out. The tests were conducted at 14 locations with varied rock composition. Before the initial tests, a loading stand was designed and constructed. A total of 201 pieces of tensile tests of bolts having lengths from 0.5 up to 2.5 m, a diameter of 22-32 mm, were performed. These were fully threaded rods, self-drilling rods, and fiberglass rods. The bolts were clamped into the cement and resin. The loading tests were always performed until material failure of bolts or shear stress failure at the interface cement-rock. At each location, basic geotechnical survey was carried out in the form of core drilling in a length of 3.0 metres with the assessment of the rock mass in situ, and laboratory testing of rock mechanics. Upon the completion of testing protocols, rock mass properties analysis was performed focusing on the evaluation of shear friction at the grouting-rock interface.

  10. Experimental study and stress analysis of rock bolt anchorage performance

    Directory of Open Access Journals (Sweden)

    Yu Chen

    2014-10-01

    Full Text Available A new method was developed to apply pull-and-shear loads to the bolt specimen in order to evaluate the anchorage performance of the rebar bolt and the D-Bolt. In the tests, five displacing angles (0°, 20°, 40°, 60°, and 90°, two joint gaps (0 mm and 30 mm, and three kinds of host rock materials (weak concrete, strong concrete, and concrete-granite were considered, and stress–strain measurements were conducted. Results show that the ultimate loads of both the D-Bolt and the rebar bolt remained constant with any displacing angles. The ultimate displacement of the D-Bolt changed from 140 mm at the 0° displacing angle (pure pull to approximately 70 mm at a displacing angle greater than 40°. The displacement capacity of the D-Bolt is approximately 3.5 times that of the rebar bolt under pure pull and 50% higher than that of the rebar bolt under pure shear. The compressive stress exists at 50 mm from the bolt head, and the maximum bending moment value rises with the increasing displacing angle. The rebar bolt mobilises greater applied load than the D-Bolt when subjected to the maximum bending. The yielding length (at 0° of the D-Bolt is longer than that of the rebar bolt. The displacement capacity of the bolts increased with the joint gap. The bolt subjected to joint gap effect yields more quickly with greater bending moment and smaller applied load. The displacement capacities of the D-Bolt and the rebar bolt are greater in the weak host rock than that in the hard host rock. In pure shear condition, the ultimate load of the bolts slightly decreases in the hard rock. The yielding speed in the hard rock is higher than that in the weak rock.

  11. Stress analysis of closure bolts for shipping casks

    International Nuclear Information System (INIS)

    Mok, G.C.; Fischer, L.E.; Hsu, S.T.

    1993-01-01

    This report specifies the requirements and criteria for stress analysis of closure bolts for shipping casks containing nuclear spent fuels or high level radioactive materials. The specification is based on existing information conceming the structural behavior, analysis, and design of bolted joints. The approach taken was to extend the ASME Boiler and Pressure Vessel Code requirements and criteria for bolting analysis of nuclear piping and pressure vessels to include the appropriate design and load characteristics of the shipping cask. The characteristics considered are large, flat, closure lids with metal-to-metal contact within the bolted joint; significant temperature and impact loads; and possible prying and bending effects. Specific formulas and procedures developed apply to the bolt stress analysis of a circular, flat, bolted closure. The report also includes critical load cases and desirable design practices for the bolted closure, an in-depth review of the structural behavior of bolted joints, and a comprehensive bibliography of current information on bolted joints

  12. TEM investigation of plant-irradiated NPP bolt material

    International Nuclear Information System (INIS)

    Pakarinen, J.; Ehrnsten, U.; Keinaenen, H.; Karlsen, W.; Karlsen, T.

    2015-01-01

    Analytical transmission electron microscopy (ATEM) was used to examine irradiation-induced damage in material removed from two different bolts from two different nuclear power plants. One section came from a French PWR, was made of CW AISI 316, and included a section of the bolt that had accumulated a dose of approximately 15 dpa during 19 operation cycles at 350 - 390 C. degrees. Another section came from a VVER bolt that was removed from the plant due to indications found in non-destructive examinations (NDE). The VVER bolt was made of solution annealed titanium stabilized 0X18H10T (corresponding to Type AISI 321) and had accumulated a fluence of 2.9 dpa. During the removal of that bolt, it was found that the bolt washer had been inappropriately spot welded to the shielding plate during assembly. Destructive investigations showed that the bolt had two large intergranular cracks, and the TEM samples were prepared from the material adjacent to those cracks. The PWR bolt had not failed, although cracks in the bolts with a similar history had been found previously. The fluence for the cold-worked AISI 316 PWR bolt was estimated to be about 15 dpa. Both the examined bolts showed a clear radiation induced segregation of alloying elements at the grain boundaries (GB-RIS), the presence of dislocation loops, the formation of precipitates, and linear deformation microstructures. Additionally, voids were found from the PWR bolt and the VVER bolt had a high density of dislocations. (authors)

  13. Decision Fusion System for Bolted Joint Monitoring

    Directory of Open Access Journals (Sweden)

    Dong Liang

    2015-01-01

    Full Text Available Bolted joint is widely used in mechanical and architectural structures, such as machine tools, industrial robots, transport machines, power plants, aviation stiffened plate, bridges, and steel towers. The bolt loosening induced by flight load and environment factor can cause joint failure leading to a disastrous accident. Hence, structural health monitoring is critical for the bolted joint detection. In order to realize a real-time and convenient monitoring and satisfy the requirement of advanced maintenance of the structure, this paper proposes an intelligent bolted joint failure monitoring approach using a developed decision fusion system integrated with Lamb wave propagation based actuator-sensor monitoring method. Firstly, the basic knowledge of decision fusion and classifier selection techniques is briefly introduced. Then, a developed decision fusion system is presented. Finally, three fusion algorithms, which consist of majority voting, Bayesian belief, and multiagent method, are adopted for comparison in a real-world monitoring experiment for the large aviation aluminum plate. Based on the results shown in the experiment, a big potential in real-time application is presented that the method can accurately and rapidly identify the bolt loosening by analyzing the acquired strain signal using proposed decision fusion system.

  14. Development of a smart rock bolt for underground monitoring operations

    CSIR Research Space (South Africa)

    Moema, JS

    2003-07-01

    Full Text Available of magnetic methods in measuring the stress or microstructural transformation in an individual bolt in both laboratory and underground environment. The corrosion performance of the smart bolt alloy was evaluated in synthetic mine water and compared...

  15. More Nuts and Bolts of Michaelis-Menten Enzyme Kinetics

    Science.gov (United States)

    Lechner, Joseph H.

    2011-01-01

    Several additions to a classroom activity are proposed in which an "enzyme" (the student) converts "substrates" (nut-bolt assemblies) into "products" (separated nuts and bolts) by unscrewing them. (Contains 1 table.)

  16. 19 CFR 10.58 - Bolting cloths; marking.

    Science.gov (United States)

    2010-04-01

    ... TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. General Provisions Bolting Cloths... used in the act or process of grading, screening, bolting, separating, classifying, or sifting dry...

  17. Hand grip function assessed by the box and block test is affected by object surfaces.

    Science.gov (United States)

    Seo, Na Jin; Enders, Leah R

    2012-01-01

    N/A. One of the hand function assessment tools is the Box and Block Test (BBT). To examine if the BBT score is affected by grip surfaces. Thirteen adults performed the BBT with wooden, rubber-covered, and paper-covered blocks. The BBT scores and time for seven movements (finger closing, contact to lift-off, transport before barrier, transport after barrier, release, return, and reach) were compared across the three block types. The mean BBT score was 8% higher for the rubber blocks than the paper and wooden blocks (pblock until the block is lifted). Hand function assessments should be controlled for object surfaces. Therapists may vary grip difficulties by changing object surfaces. Redesigning daily objects with high-friction surfaces may increase grip function. N/A. Copyright © 2012 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

  18. Ultimate load capacities of expansion anchor bolts

    International Nuclear Information System (INIS)

    Czarnecki, R.M.; Manrique, M.A.; Samaddar, S.K.

    1993-01-01

    A summary of available experimental expansion anchor bolt test data is presented. These data were collected as part of programs by the nuclear industry to address generic issues related to verification of seismic adequacy of equipment in nuclear power plants. Some of the data presented are suitable for use in seismic probabilistic risk assessments. For example, mean values of ultimate strength, along with their standard deviation and coefficients of variation, for a range of most typical expansion anchor bolt sizes are presented. Effects of interaction between shear and tension, edge distance, spacing, and cracking of the concrete are presented in a manner that is more suitable for use in deterministic evaluations. Related industry programs to derive anchor bolt capacities are briefly discussed. Recommendations for areas of further investigation are also presented

  19. Engineering Properties of Bolts and Nuts in Lagos State, Nigeria ...

    African Journals Online (AJOL)

    In steel construction, the importance of connection cannot be overemphasized. Steel connection can be made of bolts, rivets and welding. The quality of bolts, rivets and welds in structural steel connection affects the connection and hence the capacity of the whole steel structure. This paper examined the quality of bolts and ...

  20. 21 CFR 137.255 - Bolted white corn meal.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Bolted white corn meal. 137.255 Section 137.255 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Flours and Related Products § 137.255 Bolted white corn meal. (a) Bolted white corn meal is the food...

  1. Study on Fatigue Performance of Composite Bolted Joints with Bolt-Hole Delamination

    Science.gov (United States)

    Liu, M. J.; Yu, S.; Zhao, Q. Y.

    2018-03-01

    Fatigue performance of composite structure with imperfections is a challenging subject at present. Based on cohesive zone method and multi-continuum theory, delamination evolution response and fatigue life prediction of a 3D composite single-lap joint with a bolt-hole have been investigated through computer codes Abaqus and Fe-safe. Results from the comparison of a perfect composite bolted joint with another defect one indicates that a relatively small delamination damage around the bolt hole brings about significant degradation of local material performance. More notably, fatigue life of stress concentration region of composite bolted joints is highly sensitive to external loads, as an increase of 67% cyclic load amplitude leads to an decrease of 99.5% local fatigue life in this study. However, the numerical strategy for solving composite fatigue problems is meaningful to engineering works.

  2. Investigation of Reliabilities of Bolt Distances for Bolted Structural Steel Connections by Monte Carlo Simulation Method

    Directory of Open Access Journals (Sweden)

    Ertekin Öztekin Öztekin

    2015-12-01

    Full Text Available Design of the distance of bolts to each other and design of the distance of bolts to the edge of connection plates are made based on minimum and maximum boundary values proposed by structural codes. In this study, reliabilities of those distances were investigated. For this purpose, loading types, bolt types and plate thicknesses were taken as variable parameters. Monte Carlo Simulation (MCS method was used in the reliability computations performed for all combination of those parameters. At the end of study, all reliability index values for all those distances were presented in graphics and tables. Results obtained from this study compared with the values proposed by some structural codes and finally some evaluations were made about those comparisons. Finally, It was emphasized in the end of study that, it would be incorrect of the usage of the same bolt distances in the both traditional designs and the higher reliability level designs.

  3. Inedible Nuts and Non-Lightning Bolts

    Science.gov (United States)

    Rynone, William

    2010-01-01

    In this article, the author provides detailed information on a wide variety of commonly used screws, bolts, and other fasteners. The information has been gathered in his engineering career and outside interests (maintenance on his car and airplane, and woodworking). The topic should be of interest to students and educators in many technical…

  4. Earthquake friction

    Science.gov (United States)

    Mulargia, Francesco; Bizzarri, Andrea

    2016-12-01

    Laboratory friction slip experiments on rocks provide firm evidence that the static friction coefficient μ has values ∼0.7. This would imply large amounts of heat produced by seismically active faults, but no heat flow anomaly is observed, and mineralogic evidence of frictional heating is virtually absent. This stands for lower μ values ∼0.2, as also required by the observed orientation of faults with respect to the maximum compressive stress. We show that accounting for the thermal and mechanical energy balance of the system removes this inconsistence, implying a multi-stage strain release process. The first stage consists of a small and slow aseismic slip at high friction on pre-existent stress concentrators within the fault volume but angled with the main fault as Riedel cracks. This introduces a second stage dominated by frictional temperature increase inducing local pressurization of pore fluids around the slip patches, which is in turn followed by a third stage in which thermal diffusion extends the frictionally heated zones making them coalesce into a connected pressurized region oriented as the fault plane. Then, the system enters a state of equivalent low static friction in which it can undergo the fast elastic radiation slip prescribed by dislocation earthquake models.

  5. A Review of Rock Bolt Monitoring Using Smart Sensors.

    Science.gov (United States)

    Song, Gangbing; Li, Weijie; Wang, Bo; Ho, Siu Chun Michael

    2017-04-05

    Rock bolts have been widely used as rock reinforcing members in underground coal mine roadways and tunnels. Failures of rock bolts occur as a result of overloading, corrosion, seismic burst and bad grouting, leading to catastrophic economic and personnel losses. Monitoring the health condition of the rock bolts plays an important role in ensuring the safe operation of underground mines. This work presents a brief introduction on the types of rock bolts followed by a comprehensive review of rock bolt monitoring using smart sensors. Smart sensors that are used to assess rock bolt integrity are reviewed to provide a firm perception of the application of smart sensors for enhanced performance and reliability of rock bolts. The most widely used smart sensors for rock bolt monitoring are the piezoelectric sensors and the fiber optic sensors. The methodologies and principles of these smart sensors are reviewed from the point of view of rock bolt integrity monitoring. The applications of smart sensors in monitoring the critical status of rock bolts, such as the axial force, corrosion occurrence, grout quality and resin delamination, are highlighted. In addition, several prototypes or commercially available smart rock bolt devices are also introduced.

  6. Bolting Cabin Assistance System Using a Sensor Network

    Directory of Open Access Journals (Sweden)

    Yung-Hak Mo

    2012-10-01

    Full Text Available The bolting cabin assistance system prevents operators from facing dangerous situations. This system consists of a bolting robot control system and a top view supervisory system. In order to control the bolting robot, circular Hough transforms and fuzzy reasoning are used. First, the circular Hough transform roughly estimates the location of the bolt hole. After that, errors of estimation are compensated for using fuzzy reasoning. In order to track a bolt hole, a region of interest (ROI is used. By setting the region in which to search for a bolt hole, the algorithm tracks the location of the bolt hole. In order to choose an ROI, a template-based matching algorithm is used. In order to make the top view supervisory system, four cameras are installed at the left, right, front and back of the robot. The four individual images from the various cameras are combined to make the top view image after correcting for distortion.

  7. The design and testing of subscale smart aircraft wing bolts

    International Nuclear Information System (INIS)

    Vugampore, J M V; Bemont, C

    2012-01-01

    Presently costly periodic inspection is vital in guaranteeing the structural integrity of aircraft. This investigation assesses the potential for significantly reducing aircraft maintenance costs without modification of aircraft structures by implementing smart wing bolts, manufactured from TRIP steel, which can be monitored for damage in situ. TRIP steels undergo a transformation from paramagnetic austenite to ferromagnetic martensite during deformation. Subscale smart aircraft wing bolts were manufactured from hot rolled TRIP steel. These wing bolts were used to demonstrate that washers incorporating embedded inductance coils can be utilized to measure the martensitic transformation occurring in the TRIP steel during bolt deformation. Early in situ warning of a critical bolt stress level was thereby facilitated, potentially reducing the costly requirement for periodic wing bolt removal and inspection. The hot rolled TRIP steels that were utilized in these subscale bolts do not however exhibit the mechanical properties required of wing bolt material. Thus warm rolled TRIP steel alloys were also investigated. The mechanical properties of the best warm rolled TRIP steel alloy tested almost matched those of AISI 4340. The warm rolled alloys were also shown to exhibit transformation before yield, allowing for earlier warning when overload occurs. Further work will be required relating to fatigue crack detection, environmental temperature fluctuation and more thorough material characterization. However, present results show that in situ early detection of wing bolt overload is feasible via the use of high alloy warm rolled TRIP steel wing bolts in combination with inductive sensor embedded washers. (paper)

  8. GRIP HURRICANE IMAGING RADIOMETER (HIRAD) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Hurricane Imaging Radiometer (HIRAD) V1 dataset contains measurements of brightness temperature taken at 4, 5, 6 and 6.6 GHz, as well as MERRA 2 m wind...

  9. GRIP LIGHTNING INSTRUMENT PACKAGE (LIP) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Lightning Instrument Package (LIP) dataset was collected by the Lightning Instrument Package (LIP), which consists of 6 rotating vane type electric field...

  10. Adjustment of gripping force by optical systems

    Science.gov (United States)

    Jalba, C. K.; Barz, C.

    2018-01-01

    With increasing automation, robotics also requires ever more intelligent solutions in the handling of various tasks. In this context, many grippers must also be re-designed. For this, they must always be adapted for different requirements. The equipment of the gripper systems with sensors should help to make the gripping process more intelligent. In order to achieve such objectives, optical systems can also be used. This work analyzes how the gripping force can be adjusted by means of an optical recognition. The result of this work is the creation of a connection between optical recognition, tolerances, gripping force and real-time control. In this way, algorithms can be created, with the aid of which robot grippers as well as other gripping systems become more intelligent.

  11. GRIP FLIGHT TRACKS AND ANIMATIONS V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Flight Tracks and Animations dataset includes both KML files and animation files. The KML files use Google Earth to show the flight tracks on a map. The...

  12. GRIP DC-8 DROPSONDE V3

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP DC-8 Dropsonde V3 dataset consists of atmospheric pressure, dry-bulb temperature, dew point temperature, relative humidity, wind direction, wind speed, and...

  13. Investigation of Fastening Performance of Subminiature Serrated Bolt

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Myung Guen; Jeong, Jin Hwan; Jang, Yeon Hui; Kim, Hee Cheol; Kim, Jong-Bong [Seoul Nat’l Univ. of Science & Tech, Seoul (Korea, Republic of)

    2017-04-15

    As the size of electric products such as mobile phones and smart watches decrease, the bolts used to assemble these products should also be miniaturized. A miniature-sized bolt has to provide sufficient joining torque and anti-releasing torque to keep the components together. We studied a serrated bolt as a candidate for a miniature-sized fastener to increase the anti-releasing torque. In a serrated bolt, a serrated shape is formed on the bottom surface of the bolt head to create an obstacle to releasing. In this study, finite element analyses for the joining and releasing of bolts were carried out, and the anti-releasing performance was predicted. Based on the results of analyses using various numbers of serrations and fastening depths, the effects of the number of serrations and fastening depth on the anti-releasing performance were investigated.

  14. Investigation of Fastening Performance of Subminiature Serrated Bolt

    International Nuclear Information System (INIS)

    Jang, Myung Guen; Jeong, Jin Hwan; Jang, Yeon Hui; Kim, Hee Cheol; Kim, Jong-Bong

    2017-01-01

    As the size of electric products such as mobile phones and smart watches decrease, the bolts used to assemble these products should also be miniaturized. A miniature-sized bolt has to provide sufficient joining torque and anti-releasing torque to keep the components together. We studied a serrated bolt as a candidate for a miniature-sized fastener to increase the anti-releasing torque. In a serrated bolt, a serrated shape is formed on the bottom surface of the bolt head to create an obstacle to releasing. In this study, finite element analyses for the joining and releasing of bolts were carried out, and the anti-releasing performance was predicted. Based on the results of analyses using various numbers of serrations and fastening depths, the effects of the number of serrations and fastening depth on the anti-releasing performance were investigated.

  15. On analysis and redesign of bolted L-flanged connections

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard

    2017-01-01

    and the tensile force in the bolt. In the literature and also in standards,different models are presented for this important non-linear response. In the present paper, a simplified expression for the non-linear force response is presented based on finite element calculations using contact analysis. The L......In wind turbine towers, the preferred design is circular tubes that are connected by a bolted flange joint. The design is typically that of an L-flange resulting in an eccentrically loaded bolted connection. The eccentricity results in a non-linear relationship between external load on the tower......-flange connection is in essence a bad design because it leads to a non-optimal ratio between external force and bolt force. Furthermore,bolt bending results in an even higher bolt stress resulting in a reduction of strength. The present paper presents simple modifications of the L-flange design that considerably...

  16. Behaviour of Frictional Joints in Steel Arch Yielding Supports

    Czech Academy of Sciences Publication Activity Database

    Horyl, P.; Šňupárek, Richard; Maršálek, P.

    2014-01-01

    Roč. 59, č. 3 (2014), s. 723-734 ISSN 0860-7001 R&D Projects: GA MŠk ED2.1.00/03.0082; GA MŠk ED1.1.00/02.0070 Institutional support: RVO:68145535 Keywords : steel arch yielding support * friction al joints * bolt connection * slip support * fem Subject RIV: DH - Mining, incl. Coal Mining Impact factor: 0.608, year: 2013

  17. Limit load analysis of bolted flange connections

    International Nuclear Information System (INIS)

    Kauer, R.; Deininger, J.

    2005-01-01

    In Europe as well as in other countries a lot of efforts are invested into developing new codes and standards for bolted joints under various loading conditions. The standardization of gasket factors and the improvement of calculation methods with respect to these factors characterize the last couple of years in this area. In Germany, the nuclear code (KTA-Regeln) is also influenced by this development. So, the leak rate dependency of gasket factors and the results of a research program on metal-to-metal contact type flanges were introduced into the new approach of the code for Class 2 and 3 components. Herein; flange calculations can be performed for various flange types, floating type and metal-to-metal contact type. Generally, the calculations to be performed can be separated into a design step and the proof of sufficient tightness and strength of flange, bolts and gasket for the various operating conditions according to the chosen bolting method. In Europe, the most recent development in the field of flange calculations is the new standard EN 1591-1 for flange connections. The structure of the EN 1591-1 is also a two-step approach, but due to the more sophisticated and iterative calculation method, the design step is neglected and instead the focus in the first step is the determination of a suitable bolting force. In cases, where the allowable stress values are not satisfied by performing code calculations or in cases, where the applicability of the code is not given, e. g. due to geometric facts, Finite-Element analyses often replace code calculations but have to demonstrate code compliance. Therefore, numerical Finite-Element analyses, performed according to a special code, e. g. KTA, must also fulfill the requirements of the code with respect to considered load cases, bolting condition, allowable stresses etc., to get an adequate testimony for a certain flange joint. Usually this can be done by checking relevant cross sections according to the stress

  18. ["Bolt projectiles" discharged from modified humane killers (author's transl)].

    Science.gov (United States)

    Pollak, S; Reiter, C

    1981-01-01

    Some common types of "humane killers" are supplied with rubber bushings and recoil springs holding back the bolt, which afterwards is rebound into the barrel. Removal of the rubber bush and withdrawal spring before firing can cause the bolt to break and become a free projectile. A suicide case is reported, in which a livestock stunner discharged a steel bolt penetrating the forehead and getting stuck in the skull.

  19. Accidental Bolt Gun Injury to Femur - A Case Report

    OpenAIRE

    Kattimani, Ravi Prasad; Shetty, Sanath; Mirza, Humayun

    2016-01-01

    Introduction: Bolt gun or slaughterer?s guns are used in meat industry for ?humane killing? of animals. Injuries caused by bolt gun are rare, reported exclusively from central European countries. We report a case of 28 year old male, who accidentally shot himself with a bolt gun to his right thigh. Case Report: A 28 years old male presented to our Accident and Emergency department after accidental injury to his right thigh with bolt gun. He had an entry wound measuring 2 cm in length and 1 cm...

  20. Investigation of the Chooz-A nuclear power plant bolts

    International Nuclear Information System (INIS)

    Monnet, I.; Decroix, G.M.; Dubuisson, P.; Reuchet, J.; Morlent, O.

    2002-01-01

    In Pressurised Water Reactor, some baffle-former bolts in austenitic stainless steel, are submitted to an important Intergranular cracking. This cracking may be attributed to the irradiation hardening during in pile service. As part of its concern of safety related to the ageing of the plant and, in particular, to the behaviour of the internals, IRSN wished to take part in the expertise Program on CHOOZ A power nuclear plant, within the framework of a convention with EDF, which provided the baffle-bolts. Examinations of these bolts, after 140 000 of in pile service, were carried out by the laboratories of the CEA. Hardness profiles were carried out on four bolts, which were irradiated at different doses, ranging from 0 to 22 dpa. The bolt of the core barrel, considered as unirradiated, shows a constant value of hardness, equal to the value of unirradiated material, all along the bolt and a slight increase in the head of the screw. The axial profile of hardness carried out on an irradiated bolt shows that there is a gradient of hardness between the most irradiated part (400 Hv) and the least irradiated part (270 Hv). The hardness of this bolt starts to evolve at 2.5 dpa and the maximum of hardening is reached for the most irradiated part (3.6 dpa). The hardness profile on the most irradiated bolt (between 10 and 22 dpa) indicate that hardness is homogeneous all along the bolt, 400 Hv. It confirms the existence of a threshold dose beyond which hardness does not vary any more, this threshold is estimated to be between 3.6 dpa and 10 dl Microstructural examinations of these bolts led us to conclude that hardening is correlated to dislocation microstructure. Indeed, the examination of the bolt of the core barrel confirms that this bolt is hardly unirradiated since the initial network of dislocations was not modified and that only some rare dislocation loops were observed. This is in agreement with hardness results showing no hardening of this bolt. On the two more

  1. External Tank (ET) Bipod Fitting Bolted Attachment Locking Insert Performance

    Science.gov (United States)

    Larsen, Curtis E.; Wilson, Tim R.; Elliott, Kenny B.; Raju, Ivatury S.; McManamen, John

    2008-01-01

    Following STS-107, the External Tank (ET) Project implemented corrective actions and configuration changes at the ET bipod fitting. Among the corrective actions, the existing bolt lock wire which provided resistance to potential bolt rotation was removed. The lock wire removal was because of concerns with creating voids during foam application and potential for lock wire to become debris. The bolts had been previously lubricated to facilitate assembly but, because of elimination of the lock wire, the ET Project wanted to enable the locking feature of the insert. Thus, the lubrication was removed from bolt threads and instead applied to the washer under the bolt head. Lubrication is necessary to maximize joint pre-load while remaining within the bolt torque specification. The locking feature is implemented by thread crimping in at four places in the insert. As the bolt is torqued into the insert the bolt threads its way past the crimped parts of the insert. This provides the locking of the bolt, as torque is required to loosen the joint after clamping.

  2. Maintaining mine roadway using rock bolts. Rock bolt ni yoru kodo iji

    Energy Technology Data Exchange (ETDEWEB)

    Fujino, T. (Taiheiyo Coal Mining Co. Ltd., Tokyo (Japan))

    1992-11-01

    This paper describes the rock bolt method, devices and construction experiences in maintaining mine roadway drilling with Wombat-type rock bolt drilling and driving machines. Keeping the pace with coal mining zones reaching increasingly greater depths, timbering arch frames have grown larger and heavier, with frame intervals decreased. The described method was adopted to improve work efficiency and save manpowers. The Wombat, 1200-90 machine uses a driving air pressure at 7 kgf/cm[sup 2] a torque at 170 N/m to 180 N/m, and a free rotation at 800 rpm, consumes a r at 60 L/S, weighs 38 kg., and measures 1,370 mm to 3,420 mm in length. The machine is scheduled for use with three gates placed at a depth below sea level as deep as about 600 m, with gate diameters from about 5.0 m to 5.5 m and a length of about 8000 m. Effectiveness and safety of the rock bolts were verified using an extensometer made in the U.S.A. Roof subsidence after a working face has been drilled to 20 m to 30 m was about one third of that when no rock bolts were used, thus the adaptability of the method was verified. Although the drilling technique using the Wombat machine has taken roots at this particular coal mine, problems still remain such as in workability, for which further efficiency improvement and manpower saving are desired. 4 figs., 3 tabs.

  3. Hand-grip isometric strength in judo

    Directory of Open Access Journals (Sweden)

    Juan G Bonitch-Góngora

    2014-02-01

    Full Text Available The grip is an important technical and tactical aspect through which the judokas dominate the adversary, hindering the application of appropriate techniques and favoring their own attack. The judokas must have high levels of isometric force and endurance to this type of force on the gripping muscles of the forearms, as one of the key aspects for success. This article reviews the grip muscular strength and endurance profiles of judokas of different groups (gender, age and competitive level. In general, the peak isometric strength of elite judokas has not changed in the last 40 years and is similar to that reached by non-elite judokas or even registered in large populations. This indicate that the evaluation of the isometric hand grip endurance may be a more relevant parameter than the peak isometric force in judokas, as during the bouts the grip must be maintained for relatively long periods of time and the maximum force cannot be maintained for long. However there are few studies on the ability to resist successive isometric handgrip stress in judokas.

  4. GRIPS - The Geostationary Remote Infrared Pollution Sounder

    Science.gov (United States)

    Spackman, Ryan; Dickerson, Russell; Schoeberl, Mark; Bloom, Hal; Gordley, Larry; McHugh, Martin; Thompson, Anne; Burrows, John; Zeng, Ning; Marshall, Tom; Fish, Chad; Kim, Jhoon; Park, Rokjin; Warner, Juying; Bhartia, Pawan; Kollonige, Debra

    2013-04-01

    Climate change and air quality are the most pressing environmental issues of the 21st century for America and for the world as a whole. Despite decades of research, the sources and sinks of key greenhouse gases and other pollutants remain highly uncertain making atmospheric composition predictions difficult. The Geostationary Remote Infrared Pollution Sounder (GRIPS) will measure carbon dioxide (CO2), carbon monoxide (CO), and methane (CH4). By using measurements of nitrous oxide (N2O) and the O2 A-band to help correct for clouds and aerosols, GRIPS will achieve unprecedented precision. Together these gases account for about 85% of all climate forcing and they impact atmospheric ozone (O3). GRIPS, employing gas-filter correlation radiometry, uses the target gases themselves in place of dispersive elements to achieve outstanding throughput, sensitivity, and specificity. Because it uses a combination of reflected and thermal IR, GRIPS will detect trace gas concentrations right down to the Earth's surface. When flown in parallel to a UV/VIS sensor such as GEMS on GEO-KOMPSAT-2B over East Asia or the Sentinel 4 on MTG over Europe/Africa, the combination offers powerful finger-printing capabilities to distinguish and quantify diverse pollution sources such as electricity generation, biomass burning, and motor vehicles. From geostationary orbit, GRIPS will be able to focus on important targets to quantify sources, net flux, diurnal cycles, and long-range transport of these key components in the Earth's radiative balance and air quality.

  5. Multiple-bolted joints in wood members : a literature review

    Science.gov (United States)

    Peter James Moss

    1997-01-01

    This study reviewed the literature on experimental and analytical research for the connection of wood members using multiple laterally loaded bolts. From this, the influence of geometric factors were ascertained, such as staggered and aligned fasteners, optimum fastener configurations, row factors and length-to-diameter bolt ratios, spacing, end and edge distances, and...

  6. 21 CFR 137.280 - Bolted yellow corn meal.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Bolted yellow corn meal. 137.280 Section 137.280 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... definition and standard of identity prescribed by § 137.255 for bolted white corn meal except that cleaned...

  7. 9 CFR 313.15 - Mechanical; captive bolt.

    Science.gov (United States)

    2010-01-01

    ... INSPECTION AND CERTIFICATION HUMANE SLAUGHTER OF LIVESTOCK § 313.15 Mechanical; captive bolt. The... under the Act. (a) Application of stunners, required effect; handling. (1) The captive bolt stunners shall be applied to the livestock in accordance with this section so as to produce immediate...

  8. New damage-sensitive feature for structures with bolted joints

    Science.gov (United States)

    Luo, W. F.; Yu, L.

    2017-05-01

    Compared with riveted and welded joints, bolted joints have advantages of easily dismantled, high load carrying and load-transferring capacity. However, bolted joints are also weaker components of assembled structures. Structural damage detection (SDD) on bolted joints is much required in the field of structural health monitoring (SHM). A new SDD method is proposed for damage identification of structures with bolted joints based on residual error of AR model in time series analysis. Firstly, a new data standardization process is defined to maintain the information of damage location. Then, a new structural damage feature sensitive to structural damage is developed based on the standard deviation of AR model residual errors. To verify the proposed method, a bolted joint structure is designed and fabricated in laboratory, connection damages of structures are simulated by loosening the bolted joints. The acceleration responses of structures with bolted joints under healthy and damage cases are acquired. Finally, the SDD is performed by traditional DSF and the new DSF. The illustrated results show that the proposed method is a hybrid tool for the bolted joint damage detection with the new damage-sensitive feature. In addition, some related issues will be discussed as well.

  9. Strength of Glued-in Bolts after Full Scale Loading

    DEFF Research Database (Denmark)

    Pedersen, Martin Bo Uhre; Clorius, Christian Odin; Damkilde, Lars

    1999-01-01

    of the residual strength of the glued-in bolts that served as the blade to rotor hub connection in the windmill. The load history of the bolts, the test method, the observed fracture modes and the force displacement curves are presented along with the recorded residual strength of the bolts. The bolts...... with a length of 500 mm had a special hollow tapering giving them a higher load bearing capacity than solid bolts of equal dimensions. A FEM-analysis confirms the higher load bearing capacity. The mean residual strength was found to be 362 kN with a standard deviation of 37 kN, which is 95% of the predicted...

  10. Fingerprints are unlikely to increase the friction of primate fingerpads.

    Science.gov (United States)

    Warman, Peter H; Ennos, A Roland

    2009-07-01

    It is generally assumed that fingerprints improve the grip of primates, but the efficiency of their ridging will depend on the type of frictional behaviour the skin exhibits. Ridges would be effective at increasing friction for hard materials, but in a rubbery material they would reduce friction because they would reduce contact area. In this study we investigated the frictional performance of human fingertips on dry acrylic glass using a modified universal mechanical testing machine, measuring friction at a range of normal loads while also measuring the contact area. Tests were carried out on different fingers, fingers at different angles and against different widths of acrylic sheet to separate the effects of normal force and contact area. The results showed that fingertips behaved more like rubbers than hard solids; their coefficients of friction fell at higher normal forces and friction was higher when fingers were held flatter against wider sheets and hence when contact area was greater. The shear stress was greater at higher pressures, suggesting the presence of a biofilm between the skin and the surface. Fingerprints reduced contact area by a factor of one-third compared with flat skin, however, which would have reduced the friction; this casts severe doubt on their supposed frictional function.

  11. Evaluation of bolted connections in wood-plastic composites

    Science.gov (United States)

    Arnandha, Yudhi; Satyarno, Iman; Awaludin, Ali; Irawati, Inggar Septia; Ihsan, Muhamad; Wijanarko, Felyx Biondy; William, Mahdinur, Fardhani, Arfiati

    2017-03-01

    Wood-plastic composite (WPC) is a relatively new material that consists of sawdust and plastic polymer using the extrusion process. Due to its attributes such as low water content, low maintenance, UV durability and being fungi and termite resistant. Nowadays, WPC has already been produced in Indonesia using sawdust from local wood such as Albizia (Paraserianthes falcataria) and Teak (Tectona grandis). Moreover preliminary studies about the physical and mechanical WPC board from Albizia sawdust and HDPE plastic have been carried out. Based on these studies, WPC has a high shear strength around 25-30 MPa higher than its original wood shear strength. This paper was a part of the research in evaluating WPC as potential sheathing in a shear wall system. Since still little is known about connection behavior in WPC using Indonesian local wood, this study evaluated the connection for both of these two types of wood-plastic composite. WPC board from Albizia sawdust will be projected as shear wall sheathing and WPC stud from Teak sawdust projected to be shear wall frame. For this study, the embedding strength for both WPC was determined according to ASTM D 5764 standard, using two types of bolts (stainless bolt and standard bolt) with several diameters as variation (6 mm, 8 mm, 10 and 12 mm). Hence, dowel-bearing test under fastened condition conducted accordance to ASTM D5652, hereby the yield strength then compared with the prediction yield strength from European Yield Model (EYM). According to both single and double shear connection, it can be concluded that yield strength from the EYM method tended to under-predict the 5% diameter offset yield than the actual yield strength from the test. The yield strength itself increase with the increase of bolt diameter. For single shear connection, the highest yield strength was 12 mm standard bolt around 9732 N, slightly higher than stainless bolt around 9393 N. Whereby for double shear connection, the highest yield strength was

  12. GRIP METEOSAT SECOND GENERATION (MSG) IMAGE DATA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Meteosat Second Generation (MSG) data and browse was collected during the Genesis and Rapid Intensification Processes (GRIP) experiment from 15 Aug 2010 to...

  13. GRIP WB-57 NAVIGATION AND HOUSEKEEPING DATA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP WB-57 Navigation data was collected on flight days occuring between July 13 , 2010 to September 17, 2010 during the GRIP field campaign. The NASA WB-57 is a...

  14. GRIP DC-8 NAVIGATION AND HOUSEKEEPING DATA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP DC-8 Navigation and Housekeeping Data contains aircraft navigational data obtained during the GRIP campaign (15 Aug 2010 - 30 Sep 2010). The major goal was...

  15. GRIP GLOBAL HAWK NAVIGATION AND HOUSEKEEPING DATA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Global Hawk Navigation data was collected during the period Aug 15, 2010 to September 24, 2010 during the GRIP field campaign. The Global Hawk is an...

  16. GRIP METEOSAT SECOND GENERATION (MSG) IMAGE DATA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Meteosat Second Generation (MSG) Image Data was collected during the Genesis and Rapid Intensification Processes (GRIP) experiment from August 15, 2010 to...

  17. The GRIP method for collaborative roadmapping workshops

    DEFF Research Database (Denmark)

    Piirainen, Kalle

    2015-01-01

    Technology roadmapping is a well-known tool for technology management, but practical advice for facilitating collaborative roadmapping workshops is relatively scarce. To cater for this need, we have designed a method for collaborative roadmapping, dubbed the GRIP method, for facilitating group work...

  18. Corrosion fracture of bolts of nuclear power steam generators

    International Nuclear Information System (INIS)

    Hrivnak, I.

    1990-01-01

    Bolts connecting collector bodies with lids were the first components of steam generators at Czechoslovak WWER-440 units on which corrosion damage was observed in 1982 to 1983. Corrosion cracks developed particularly in the cylindrical parts of the bolts. This was due to intergranular corrosion caused by the unsuitable chemical composition of the steel used, by secondary water level fluctuations, by the surrounding environment of the bolts being unamenable to deaeration, as well as by inappropriate tightening of the bolts which gave rise to additional deformation stress. Steps were taken to eliminate all these drawbacks, and owing to this the corrosion cracking of the bolts was prevented for longer than 6 years. Cracks were observed again in 1989; they occurred then not only in the cylindrical parts but also in the thread parts of the bolts. The corrosion was again of intergranular nature. As yet, the cause of the corrosion cracking of the bolts is not unambiguously known. It is largely assumed that the material used, viz. the high-strength KhN35VT nickel alloy, is exceedingly sensitive to the working procedure and to stress. (Z.M.)

  19. Evaluation of Rock Bolt Support for Polish Hard Rock Mines

    Science.gov (United States)

    Skrzypkowski, Krzysztof

    2018-03-01

    The article presents different types of rock bolt support used in Polish ore mining. Individual point resin and expansion rock bolt support were characterized. The roof classes for zinc and lead and copper ore mines were presented. Furthermore, in the article laboratory tests of point resin rock bolt support in a geometric scale of 1:1 with minimal fixing length of 0.6 m were made. Static testing of point resin rock bolt support were carried out on a laboratory test facility of Department of Underground Mining which simulate mine conditions for Polish ore and hard coal mining. Laboratory tests of point resin bolts were carried out, especially for the ZGH Bolesław, zinc and lead "Olkusz - Pomorzany" mine. The primary aim of the research was to check whether at the anchoring point length of 0.6 m by means of one and a half resin cartridge, the type bolt "Olkusz - 20A" is able to overcome the load.The second purpose of the study was to obtain load - displacement characteristic with determination of the elastic and plastic range of the bolt. For the best simulation of mine conditions the station steel cylinders with an external diameter of 0.1 m and a length of 0.6 m with a core of rock from the roof of the underground excavations were used.

  20. Epigenomics and bolting tolerance in sugar beet genotypes.

    Science.gov (United States)

    Hébrard, Claire; Peterson, Daniel G; Willems, Glenda; Delaunay, Alain; Jesson, Béline; Lefèbvre, Marc; Barnes, Steve; Maury, Stéphane

    2016-01-01

    In sugar beet (Beta vulgaris altissima), bolting tolerance is an essential agronomic trait reflecting the bolting response of genotypes after vernalization. Genes involved in induction of sugar beet bolting have now been identified, and evidence suggests that epigenetic factors are involved in their control. Indeed, the time course and amplitude of DNA methylation variations in the shoot apical meristem have been shown to be critical in inducing sugar beet bolting, and a few functional targets of DNA methylation during vernalization have been identified. However, molecular mechanisms controlling bolting tolerance levels among genotypes are still poorly understood. Here, gene expression and DNA methylation profiles were compared in shoot apical meristems of three bolting-resistant and three bolting-sensitive genotypes after vernalization. Using Cot fractionation followed by 454 sequencing of the isolated low-copy DNA, 6231 contigs were obtained that were used along with public sugar beet DNA sequences to design custom Agilent microarrays for expression (56k) and methylation (244k) analyses. A total of 169 differentially expressed genes and 111 differentially methylated regions were identified between resistant and sensitive vernalized genotypes. Fourteen sequences were both differentially expressed and differentially methylated, with a negative correlation between their methylation and expression levels. Genes involved in cold perception, phytohormone signalling, and flowering induction were over-represented and collectively represent an integrative gene network from environmental perception to bolting induction. Altogether, the data suggest that the genotype-dependent control of DNA methylation and expression of an integrative gene network participate in bolting tolerance in sugar beet, opening up perspectives for crop improvement. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  1. G×E Interaction Influences Trajectories of Hand Grip Strength

    DEFF Research Database (Denmark)

    Petersen, Inge; Pedersen, Nancy L; Rantanen, Taina

    2016-01-01

    Age-related decline in grip strength predicts later life disability, frailty, lower well-being and cognitive change. While grip strength is heritable, genetic influence on change in grip strength has been relatively ignored, with non-shared environmental influence identified as the primary contri...

  2. Stiffness Analysis and Improvement of Bolt-Plate Contact Assemblies

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard; Pedersen, Pauli

    2008-01-01

    and the plate is extended by the possibility of designing a gap, that is, a nonuniform distance between the bolt and plate before prestressing. Designing the gap function generates the possibility for a better stress field by which the stiffness of the bolt is lowered, and at the same time the stiffness...... of the members is increased. Both of these changes have a positive influence on the lifetime of the connections. From designing a varying gap size distribution, it is found that the stiffness become a function of the loading. It is shown that similar improvements in the stiffness ratio between the bolt...

  3. An eight-legged tactile sensor to estimate coefficient of static friction.

    Science.gov (United States)

    Wei Chen; Rodpongpun, Sura; Luo, William; Isaacson, Nathan; Kark, Lauren; Khamis, Heba; Redmond, Stephen J

    2015-08-01

    It is well known that a tangential force larger than the maximum static friction force is required to initiate the sliding motion between two objects, which is governed by a material constant called the coefficient of static friction. Therefore, knowing the coefficient of static friction is of great importance for robot grippers which wish to maintain a stable and precise grip on an object during various manipulation tasks. Importantly, it is most useful if grippers can estimate the coefficient of static friction without having to explicitly explore the object first, such as lifting the object and reducing the grip force until it slips. A novel eight-legged sensor, based on simplified theoretical principles of friction is presented here to estimate the coefficient of static friction between a planar surface and the prototype sensor. Each of the sensor's eight legs are straight and rigid, and oriented at a specified angle with respect to the vertical, allowing it to estimate one of five ranges (5 = 8/2 + 1) that the coefficient of static friction can occupy. The coefficient of friction can be estimated by determining whether the legs have slipped or not when pressed against a surface. The coefficients of static friction between the sensor and five different materials were estimated and compared to a measurement from traditional methods. A least-squares linear fit of the sensor estimated coefficient showed good correlation with the reference coefficient with a gradient close to one and an r(2) value greater than 0.9.

  4. Variability of grip kinetics during adult signature writing.

    Directory of Open Access Journals (Sweden)

    Bassma Ghali

    Full Text Available Grip kinetics and their variation are emerging as important considerations in the clinical assessment of handwriting pathologies, fine motor rehabilitation, biometrics, forensics and ergonomic pen design. This study evaluated the intra- and inter-participant variability of grip shape kinetics in adults during signature writing. Twenty (20 adult participants wrote on a digitizing tablet using an instrumented pen that measured the forces exerted on its barrel. Signature samples were collected over 10 days, 3 times a day, to capture temporal variations in grip shape kinetics. A kinetic topography (i.e., grip shape image was derived per signature by time-averaging the measured force at each of 32 locations around the pen barrel. The normalized cross correlations (NCC of grip shape images were calculated within- and between-participants. Several classification algorithms were implemented to gauge the error rate of participant discrimination based on grip shape kinetics. Four different grip shapes emerged and several participants made grip adjustments (change in grip shape or grip height or rotated the pen during writing. Nonetheless, intra-participant variation in grip kinetics was generally much smaller than inter-participant force variations. Using the entire grip shape images as a 32-dimensional input feature vector, a K-nearest neighbor classifier achieved an error rate of 1.2±0.4% in discriminating among participants. These results indicate that writers had unique grip shape kinetics that were repeatable over time but distinct from those of other participants. The topographic analysis of grip kinetics may inform the development of personalized interventions or customizable grips in clinical and industrial applications, respectively.

  5. Elastomeric friction

    Science.gov (United States)

    Vorvolakos, Katherine

    This dissertation examines the tribology of PDMS (polydimethylsiloxane) elastomers from a practical and a fundamental perspective. We examine the adhesive, energetic, and tribological properties of several commercial biofouling release coatings, and show that adhesive (and bioadhesive) release from an elastomer depends on the friction of its surface. Having shown that friction is an obstacle to release, we lubricate a model PDMS network by incorporating linear unreactive PDMS oils varying in molecular weight (0.8--423 kg/mol). Surface segregation upon curing depends on molecular weight and mass percentage. Atomic Force Microscopy (AFM) is used to detect the thickness of the lubricant layer. Surprisingly, high-viscosity oils lubricate better than low-viscosity oils, indicating a non-hydrodynamic lubrication. Applying this technology to a commercial elastomer, we see an improvement in bioadhesive release capabilities, as evidenced by a reduced tenacity of mussel adhesive protein. In comparing entangled polymer melts to crosslinked elastomers, we encountered an opportunity to study the tribology of the latter. We studied the effects of molecular weight, velocity, and temperature on the friction of crosslinked PDMS elastomers sliding against two model surfaces: a self-assembled monolayer (SAM) of n-hexadecylsilane, and a thin (˜100mum) film of polystyrene (PS). The change from smooth to stick-slip (unstable) interfacial sliding occurs at a distinct velocity on each surface, implying that it's not necessarily attributable to a bulk glass transition of the PDMS, as popularly believed. The peak shear stress attained immediately before stick-slip sliding is found to be linear with the shear modulus raised to an exponent n of ¾, in contrast with the predictions of Chernyak and Leonov ( n = 1). Low-velocity behavior differs greatly between the SAM and the PS, implying a mechanistic difference. Whereas on the SAM, sliding likely proceeds purely by stochastic adsorption and

  6. Study on Rock Bolt Reinforcement for a Gravity Dam Foundation

    Science.gov (United States)

    Chen, S. H.; Yang, Z. M.; Wang, W. M.; Shahrour, I.

    2012-01-01

    In this article, the rock bolt reinforcement mechanism is discussed, and the gravity method as well as the finite element method for the bolted rock is presented. These methods are applied to study the gravity dam foundation of the Xiaoxi Hydropower Project, which is influenced by the presence of a large fault with a cracked zone over 180 m wide. Rock bolt reinforcement was used to improve the stability of the dam foundation, and the reinforcement parameters were determined from a semi-empirical equation controlled by in situ test. The stability analysis was conducted using the above methods, and the improvement in terms of deformation and stress as well as stability of the dam foundation due to the reinforcement is assessed. Rock bolt reinforcement was completed successfully, and the dam started normal operations in January 2008.

  7. Investigation of high-strength bolt-tightening verification techniques.

    Science.gov (United States)

    2016-03-01

    The current means and methods of verifying that high-strength bolts have been properly tightened are very laborious and time : consuming. In some cases, the techniques require special equipment and, in other cases, the verification itself may be some...

  8. Preloading of bolted connections in nuclear reactor component supports

    International Nuclear Information System (INIS)

    Yahr, G.T.

    1984-10-01

    A number of failures of threaded fasteners in nuclear reactor component supports have been reported. Many of those failures were attributed to stress corrosion cracking. This report discusses how stress corrosion cracking can be avoided in bolting by controlling the maximum bolt preloads so that the sustained stresses in the bolts are below the level required to cause stress corrosion cracking. This is a basic departure from ordinary bolted joint design where the only limits on preload are on the minimum preload. Emphasis is placed on the importance of detailed analysis to determine the acceptable range of preload and the selection of a method for measuring the preload that is sufficiently accurate to ensure that the preload is actually within the acceptable range. Procedures for determining acceptable preload range are given, and the accuracy of various methods of measuring preload is discussed

  9. Design Procedure on Stud Bolt for Reactor Vessel Assembly

    International Nuclear Information System (INIS)

    Kim, Jong-Wook; Lee, Gyu-Mahn; Jeoung, Kyeong-Hoon; Kim, Tae-Wan; Park, Keun-Bae; Kim, Keung-Koo

    2008-10-01

    The reactor pressure vessel flange is welded to the upper part of reactor pressure vessel, and there are stud holes to mount the closure head with stud bolts. The surface mating the closure head is compressed with O-ring, which acts as a sealing gasket to prevent coolant leakage. Bolted flange connections perform a very important structural role in the design of a reactor pressure vessel. Their importance stems from two important functions: (a) maintenance of the structural integrity of the connection itself, and (b) prevention of leakage through the O-ring preloaded by stud bolts. In the present study, an evaluation procedure for the design of stud bolt is developed to meet ASME code requirements. The developed design procedure could provide typical references in the development of advanced reactor design in the future

  10. Piezoelectric Washer for Accurate Application of Bolt Preload

    Data.gov (United States)

    National Aeronautics and Space Administration — A concept is proposed for monitoring bolt preload that offers accuracy and low-cost features not available in existing preload monitoring systems. Existing washer...

  11. Mechanics of Re-Torquing in Bolted Flange Connections

    Science.gov (United States)

    Gordon, Ali P.; Drilling Brian; Weichman, Kyle; Kammerer, Catherine; Baldwin, Frank

    2010-01-01

    It has been widely accepted that the phenomenon of time-dependent loosening of flange connections is a strong consequence of the viscous nature of the compression seal material. Characterizing the coupled interaction between gasket creep and elastic bolt stiffness has been useful in predicting conditions that facilitate leakage. Prior advances on this sub-class of bolted joints has lead to the development of (1) constitutive models for elastomerics, (2) initial tightening strategies, (3) etc. The effect of re-torque, which is a major consideration for typical bolted flange seals used on the Space Shuttle fleet, has not been fully characterized, however. The current study presents a systematic approach to characterizing bolted joint behavior as the consequence of sequentially applied torques. Based on exprimenta1 and numerical results, the optimal re-torquing parameters have been identified that allow for the negligible load loss after pre-load application

  12. Remote bolting tools for the JET divertor exchange

    International Nuclear Information System (INIS)

    Mills, S.F.; Loving, A.B.

    1998-01-01

    With over 2500 bolting operations to perform remotely, the selection of appropriate tooling was fundamental to the efficiency of the recent JET Divertor Exchange. During mock-up trials using the Mascot force reflecting manipulator it became apparent that many traditional manual techniques were inappropriate. Hence, it was necessary to design special bolting tools to satisfy the remote handling needs. This paper discusses the evolution of this tooling. (authors)

  13. Accidental Bolt Gun Injury to Femur - A Case Report.

    Science.gov (United States)

    Kattimani, Ravi Prasad; Shetty, Sanath; Mirza, Humayun

    2016-01-01

    Bolt gun or slaughterer's guns are used in meat industry for "humane killing" of animals. Injuries caused by bolt gun are rare, reported exclusively from central European countries. We report a case of 28 year old male, who accidentally shot himself with a bolt gun to his right thigh. A 28 years old male presented to our Accident and Emergency department after accidental injury to his right thigh with bolt gun. He had an entry wound measuring 2 cm in length and 1 cm in breadth over anterior aspect of lower one third of thigh at lower and sustained Grade II compound fracture of right femur shaft at distal one third. The wound was treated with multiple debridements, negative pressure wound therapy and intravenous antibiotics based on culture and sensitivity. Bolt gun or slaughterer's guns are weapons used in meat industry for slaughtering animals. Wounds inflicted by bolt guns have specific morphological feature, distinctive from wounds made by other kinds of hand firearms. Most of the time wound will be infected at presentation. Lesions caused by these weapons are likely to have a more serious character than is to be expected from the size of the entrance wound. The mainstay of treatment is liberal wound exploration, multiple debridement's and intra venous antibiotics based on culture reports to treat infection and prevent morbidity.

  14. Friction control using ultrasonic oscillation for rolling-element linear-motion guide

    International Nuclear Information System (INIS)

    Oiwa, Takaaki

    2006-01-01

    This article reports a friction-control method for rolling-element linear-motion guides used for precision positioning. In general, static friction greater than dynamic friction generates stick-slip motion and diminishes the positioning accuracy. Two ultrasonic actuators excite both the rail and the carriage of the guide to give relative displacements to bearing surfaces. In order to effectively propagate the vibration over the entire rail without damping, the actuator drives at that frequency with a half wavelength corresponding to the distances between the rail mounting bolts. This also minimizes undesirable vibration of the machine structure. Moreover, the bearing surfaces of the carriage are resonated by a second ultrasonic actuator. The experiments using a force sensor showed that the static and dynamic friction forces were reduced by approximately 25% at any place on the 600-mm-long rail. Moreover, excitation only at very low velocity decreased the static friction peak

  15. Progress on the interface between UPP and CPRHS (Cask and Plug Remote Handling System) tractor/gripping tool for ITER

    International Nuclear Information System (INIS)

    Rosa, Elena V.; Rios, Luis; Queral, Vicente

    2013-01-01

    Highlights: ► UPP interface requirements in the plug RH extraction/insertion for ITER. ► Analyze of maximum misalignment between port duct and port cell. ► Friction study between plug skids and VV port/ramp rails during the plug transfer. ► Definition of the tolerance in the plug skids to avoid the plug jamming. ► Concepts of gripping tools based on one gripping point and avoiding force feedback. -- Abstract: EFDA finances a training programme called Goal Oriented Training Programme for Remote Handling (GOT RH), whose goal is to train engineers in Remote Handling for ITER. As part of this training programme, the conceptual design of the mechanical interface between Upper Port Plug (UPP) and Cask and Plug Remote Handling System (CPRHS) as well as the conceptual design of the needed tools for UPP Remote Handling is carried out. The paper presents the conceptual design of the UPP/Gripping Tool Interface. This includes the conceptual design of the gripping tool for introducing/removing the UPP in/from the ITER port and the mechanical features on both sides of the UPP/Gripping Tool Interface (e.g. alignment features, mechanical connectors, fasteners). In order to develop the design of the interface between UPP and CPRHS it is necessary to first identify the functional requirements of the Transfer Cask System (TCS) and the CPRHS, such as required degrees of freedom (DoF), required performances of system, geometrical constraints, loading conditions, alignment requirements, RAMI requirements. These requirements are the input data for the design of the interface between UPP and gripping tool and some of them are also described in the paper

  16. ASSESSMENT OF GRIP FORCE CONTROL IN PATIENTS WITH MUSCULAR DYSTROPHY

    Directory of Open Access Journals (Sweden)

    Gregorij Kurillo

    2004-12-01

    Full Text Available Background. The majority of hand functionality tests are based on qualitative assessment which largely depends on the experience of the therapist. Computer-assisted methods can provide more objective and accurate measurements of the grip force and other parameters related to grasping.Methods. We analysed the grip force control in 12 patients with muscular dystrophy using the tracking system developed. The system consists of a grip-measuring device with endobjects assessing the force applied in different grips. The device was used as input to a tracking task where the patient applied the grip force according to the visual feedback from the computer screen. Each patient performed two tasks which consisted of tracking a ramp and sinus target.Results. We analysed the maximal grip force as assessed in the ramp task and the tracking accuracy of the sinus task. The results are compared among five different grips (cylindrical, lateral, palmar, pinch and spherical grip, applied with dominant and non-dominant hand. The results show no significant difference in tracking accuracy between the dominant and non-dominant hand.Conclusions. The results obtained in tracking the ramp target showed that the method could be used for the assessment of the muscle fatigue, providing quantitative information on muscle capacity. The results of the sinus-tracking task showed that the method can evaluate the grip force control in different types of grips, providing information on hand dexterity, muscle activation patterns or tremor.

  17. Genetic analysis of bolting after winter in sugar beet (Beta vulgaris L.).

    Science.gov (United States)

    Pfeiffer, Nina; Tränkner, Conny; Lemnian, Ioana; Grosse, Ivo; Müller, Andreas E; Jung, Christian; Kopisch-Obuch, Friedrich J

    2014-11-01

    This study reveals for the first time a major QTL for post-winter bolting resistance in sugar beet ( Beta vulgaris L.). The knowledge of this QTL is a major contribution towards the development of a winter sugar beet with controlled bolting behavior. In cool temperate climates, sugar beets are currently grown as a spring crop. They are sown in spring and harvested in autumn. Growing sugar beet as a winter crop with an extended vegetation period fails due to bolting after winter. Bolting after winter might be controlled by accumulating genes for post-winter bolting resistance. Previously, we had observed in field experiments a low post-winter bolting rate of 0.5 for sugar beet accession BETA 1773. This accession was crossed with a biennial sugar beet with regular bolting behavior to develop a F3 mapping population. The population was grown in the greenhouse, exposed to artificial cold treatment for 16 weeks and transplanted to the field. Bolting was recorded twice a week from May until October. Post-winter bolting behavior was assessed by two different factors, bolting delay (determined as days to bolt after cold treatment) and post-winter bolting resistance (bolting rate after winter). For days to bolt, means of F3 families ranged from 25 to 164 days while for bolting rate F3 families ranged from 0 to 1. For each factor one QTL explaining about 65% of the phenotypic variation was mapped to the same region on linkage group 9 with a partially recessive allele increasing bolting delay and post-winter bolting resistance. The results are discussed in relation to the potential use of marker-assisted breeding of winter sugar beets with controlled bolting.

  18. Acoustics of friction

    Science.gov (United States)

    Akay, Adnan

    2002-04-01

    This article presents an overview of the acoustics of friction by covering friction sounds, friction-induced vibrations and waves in solids, and descriptions of other frictional phenomena related to acoustics. Friction, resulting from the sliding contact of solids, often gives rise to diverse forms of waves and oscillations within solids which frequently lead to radiation of sound to the surrounding media. Among the many everyday examples of friction sounds, violin music and brake noise in automobiles represent the two extremes in terms of the sounds they produce and the mechanisms by which they are generated. Of the multiple examples of friction sounds in nature, insect sounds are prominent. Friction also provides a means by which energy dissipation takes place at the interface of solids. Friction damping that develops between surfaces, such as joints and connections, in some cases requires only microscopic motion to dissipate energy. Modeling of friction-induced vibrations and friction damping in mechanical systems requires an accurate description of friction for which only approximations exist. While many of the components that contribute to friction can be modeled, computational requirements become prohibitive for their contemporaneous calculation. Furthermore, quantification of friction at the atomic scale still remains elusive. At the atomic scale, friction becomes a mechanism that converts the kinetic energy associated with the relative motion of surfaces to thermal energy. However, the description of the conversion to thermal energy represented by a disordered state of oscillations of atoms in a solid is still not well understood. At the macroscopic level, friction interacts with the vibrations and waves that it causes. Such interaction sets up a feedback between the friction force and waves at the surfaces, thereby making friction and surface motion interdependent. Such interdependence forms the basis for friction-induced motion as in the case of

  19. A Modelling Method of Bolt Joints Based on Basic Characteristic Parameters of Joint Surfaces

    Science.gov (United States)

    Yuansheng, Li; Guangpeng, Zhang; Zhen, Zhang; Ping, Wang

    2018-02-01

    Bolt joints are common in machine tools and have a direct impact on the overall performance of the tools. Therefore, the understanding of bolt joint characteristics is essential for improving machine design and assembly. Firstly, According to the experimental data obtained from the experiment, the stiffness curve formula was fitted. Secondly, a finite element model of unit bolt joints such as bolt flange joints, bolt head joints, and thread joints was constructed, and lastly the stiffness parameters of joint surfaces were implemented in the model by the secondary development of ABAQUS. The finite element model of the bolt joint established by this method can simulate the contact state very well.

  20. Dr. Buzby’s ToeGrips® Application Results in Minimal Changes in Kinetic Gait Parameters in Normal Dogs

    Directory of Open Access Journals (Sweden)

    James K. Roush

    2017-07-01

    Full Text Available Poor traction on slick surfaces is difficult for dogs with neurologic deficits, osteoarthritis, or recovering from injury or surgery. Many dogs respond inappropriately to slick surfaces by decreasing digital pad-floor contact and extending their toenails. A device marketed to increase paw-floor friction in dogs was evaluated. Fifteen normal dogs underwent kinetic gait analysis before and after application of Dr. Buzby’s ToeGrips®. Ground reaction forces, including vertical peak force (VPF and impulse for each limb, were measured and compared between pre- and post-application values. Stance time was significantly increased in all limbs after toe grip application. Stride velocity was slower in all limbs but significantly slower only in the left forelimb. VPF was significantly deceased in both hindlimbs after toe grip application, but the decrease was within the group SDs. Vertical impulse was significantly increased in both forelimbs and in the right hindlimb. Dr. Buzby’s ToeGrips® result in a slower gait, with slightly decreased VPF in the hindlimbs and increased effort for propulsion kinetic changes were of minor magnitude and unlikely to be clinically relevant.

  1. Mechanical Behavior of CFRP Lattice Core Sandwich Bolted Corner Joints

    Science.gov (United States)

    Zhu, Xiaolei; Liu, Yang; Wang, Yana; Lu, Xiaofeng; Zhu, Lingxue

    2017-12-01

    The lattice core sandwich structures have drawn more attention for the integration of load capacity and multifunctional applications. However, the connection of carbon fibers reinforced polymer composite (CFRP) lattice core sandwich structure hinders its application. In this paper, a typical connection of two lattice core sandwich panels, named as corner joint or L-joint, was investigated by experiment and finite element method (FEM). The mechanical behavior and failure mode of the corner joints were discussed. The results showed that the main deformation pattern and failure mode of the lattice core sandwich bolted corner joints structure were the deformation of metal connector and indentation of the face sheet in the bolt holes. The metal connectors played an important role in bolted corner joints structure. In order to save the calculation resource, a continuum model of pyramid lattice core was used to replace the exact structure. The computation results were consistent with experiment, and the maximum error was 19%. The FEM demonstrated the deflection process of the bolted corner joints structure visually. So the simplified FEM can be used for further analysis of the bolted corner joints structure in engineering.

  2. GRIP LIDAR ATMOSPHERIC SENSING EXPERIMENT (LASE) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Lidar Atmospheric Sensing Experiment (LASE) dataset was collected by NASA's Lidar Atmospheric Sensing Experiment (LASE) system, which is an airborne...

  3. GRIP LANGLEY AEROSOL RESEARCH GROUP EXPERIMENT (LARGE) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Langley Aerosol Research Group Experiment (LARGE) dataset was collected by the Langley Aerosol Research Group Experiment (LARGE), which measures ultrafine...

  4. Sliding Friction of Copper

    National Research Council Canada - National Science Library

    Liu, Tung

    1963-01-01

    .... With less clean surfaces, the coefficient of friction obtained was about 0.4. Since the degree of cleanliness cannot be controlled quantitatively, the friction - load curve of sliding copper pairs in air exhibits a bifurcation characteristic...

  5. Normal values for hand grip strength in healthy Nigerian adults ...

    African Journals Online (AJOL)

    Background: Assessment of hand grip strength is used in a wide range of clinical settings particularly during management of hand injuries and diseases affecting hand function. This study aimed to determine age and gender specific normal values of hand grip strength in healthy adults in Nigeria and compare values ...

  6. Algorithm Design for Grip-Pattern Verification in Smart Gun

    NARCIS (Netherlands)

    Shang, X.; Veldhuis, Raymond N.J.; Bazen, A.M.; Ganzevoort, W.P.T.

    2005-01-01

    The Secure Grip project1 focuses on the development of a hand-grip pattern recognition system, as part of the smart gun. Its target customer is the police. To explore the authentication performance of this system, we collected data from a group of police officers, and made authentication simulations

  7. Grip-pattern recognition: Applied to a smart gun

    NARCIS (Netherlands)

    Shang, X.

    2008-01-01

    In our work the verification performance of a biometric recognition system based on grip patterns, as part of a smart gun for use by the police ocers, has been investigated. The biometric features are extracted from a two-dimensional pattern of the pressure, exerted on the grip of a gun by the hand

  8. Preserved grip selection planning in chronic unilateral upper extremity amputees

    Science.gov (United States)

    Frey, Scott H.

    2016-01-01

    Upper limb amputees receive no proprioceptive or visual sensory feedback about their absent hand. In this study, we asked whether chronic amputees nevertheless retain the ability to accurately plan gripping movements. Fourteen patients and matched controls performed two grip selection tasks: overt grip selection (OGS), in which they used their intact hand to grasp an object that appeared in different orientations using the most natural (under- or overhand) precision grip, and prospective grip selection (PGS), in which they selected the most natural grip for either hand without moving. We evaluated planning accuracy by comparing concordance between grip preferences expressed in PGS vs. OGS for the intact hand and PGS vs. the inverse of OGS responses for the affected hand. Overall, amputees showed no deficits in the accuracy of grip selection planning based on either hand and a consistent preference for less awkward hand postures. We found no evidence for a speed-accuracy tradeoff. Furthermore, selection accuracy did not depend on phantom mobility, phantom limb pain, time since amputation, or the residual limb’s shoulder posture. Our findings demonstrate that unilateral upper limb amputees retain the ability to plan movements based on the biomechanics of their affected hand even many years after limb loss. This unimpaired representation may stem from persistent higher-level activity-independent internal representations or may be sustained by sensory feedback from the intact hand. PMID:21863261

  9. Biometric verification based on grip-pattern recognition

    NARCIS (Netherlands)

    Veldhuis, Raymond N.J.; Bazen, A.M.; Kauffman, J.A.; Hartel, Pieter H.; Delp, Edward J.; Wong, Ping W.

    This paper describes the design, implementation and evaluation of a user-verification system for a smart gun, which is based on grip-pattern recognition. An existing pressure sensor consisting of an array of 44 x 44 piezoresistive elements is used to measure the grip pattern. An interface has been

  10. Design of Multiple Bolted Connections for Laminated Veneer Lumber

    Science.gov (United States)

    Borjen Yeh; Douglas Rammer; Jeff Linville

    2014-01-01

    The design of multiple bolted connections in accordance with Appendix E of the National Design Specification for Wood Construction (NDS) has incorporated provisions for evaluating localized member failure modes of row and group tear-out when the connections are closely spaced. Originally based on structural glued laminated timber (glulam) members made with all L1...

  11. Numerical and experimental investigation of bolted joints | Jam ...

    African Journals Online (AJOL)

    In this study, the behavior and the damage caused in the bolt joints in sandwich structures with laminates made of glass fiber and foam core is investigated. Many investigators ... been designed. The results of the tests show that the results of the finite element analysis and those of the experimental results are closely related.

  12. Bolting state-building fault lines with social capital

    African Journals Online (AJOL)

    2013-12-15

    Dec 15, 2013 ... Keywords: State-building, social capital, ethnic supremacy, Dinka, Nuer,. South Sudan. * Robert Gerenge is the Head of Special Programmes at the Electoral Institute for Sustainable. Democracy in Africa (EISA). South Sudan's December 2013 conflict: Bolting state-building fault lines with social capital.

  13. Evaluation of Roof Bolting Requirements Based on In-Mine Roof Bolter Drilling

    Energy Technology Data Exchange (ETDEWEB)

    Syd S. Peng

    2005-10-01

    Roof bolting is the most popular method for underground openings in the mining industry, especially in the bedded deposits such as coal. In fact, all U.S. underground coal mine entries are roof-bolted as required by law. However, roof falls still occur frequently in the roof bolted entries. The two possible reasons are: the lack of knowledge of and technology to detect the roof geological conditions in advance of mining, and lack of roof bolting design criteria for modern roof bolting systems. This research is to develop a method for predicting the roof geology and stability condition in real time during roof bolting operation. Based on this information, roof bolting design criteria for modern roof bolting systems will be developed for implementation in real time. For the prediction of roof geology and stability condition in real time, a micro processor was used and a program developed to monitor and record the drilling parameters of roof bolter. These parameters include feed pressure, feed flow (penetration rate), rotation pressure, rotation rate, vacuum pressure, oil temperature of hydraulic circuit, and signals for controlling machine. From the results of a series of laboratory and underground tests so far, feed pressure is found to be a good indicator for identifying the voids/fractures and estimating the roof rock strength. The method for determining quantitatively the location and the size of void/fracture and estimating the roof rock strength from the drilling parameters of roof bolter was developed. Also, a set of computational rules has been developed for in-mine roof using measured roof drilling parameters and implemented in MRGIS (Mine Roof Geology Information System), a software package developed to allow mine engineers to make use of the large amount of roof drilling parameters for predicting roof geology properties automatically. For the development of roof bolting criteria, finite element models were developed for tensioned and fully grouted bolting

  14. Analysis on Sealing Reliability of Bolted Joint Ball Head Component of Satellite Propulsion System

    Science.gov (United States)

    Guo, Tao; Fan, Yougao; Gao, Feng; Gu, Shixin; Wang, Wei

    2018-01-01

    Propulsion system is one of the important subsystems of satellite, and its performance directly affects the service life, attitude control and reliability of the satellite. The Paper analyzes the sealing principle of bolted joint ball head component of satellite propulsion system and discuss from the compatibility of hydrazine anhydrous and bolted joint ball head component, influence of ground environment on the sealing performance of bolted joint ball heads, and material failure caused by environment, showing that the sealing reliability of bolted joint ball head component is good and the influence of above three aspects on sealing of bolted joint ball head component can be ignored.

  15. 3D Finite Element Modeling of Single Bolt Connections under Static and Dynamic Tension Loading

    Directory of Open Access Journals (Sweden)

    Emily Guzas

    2015-01-01

    Full Text Available The Naval Undersea Warfare Center has funded research to examine a range of finite element approaches used for modeling bolted connections subjected to various loading conditions. Research focused on developing finite element bolt representations that were accurate and computationally efficient. A variety of finite element modeling approaches, from detailed models to simplified ones, were used to represent the behavior of single solid bolts under static and dynamic tension loading. Test cases utilized models of bolted connection test arrangements (static tension and dynamic tension developed for previous research and validated against test data for hollow bore bolts (Behan et al., 2013. Simulation results for solid bolts are validated against experimental data from physical testing of bolts in these load configurations.

  16. Deciphering the complex nature of bolting time regulation in Beta vulgaris.

    Science.gov (United States)

    Tränkner, Conny; Pfeiffer, Nina; Kirchhoff, Martin; Kopisch-Obuch, Friedrich J; van Dijk, Henk; Schilhabel, Markus; Hasler, Mario; Emrani, Nazgol

    2017-08-01

    Only few genetic loci are sufficient to increase the variation of bolting time in Beta vulgaris dramatically, regarding vernalization requirement, seasonal bolting time and reproduction type. Beta species show a wide variation of bolting time regarding the year of first reproduction, seasonal bolting time and the number of reproduction cycles. To elucidate the genetics of bolting time control, we used three F 3 mapping populations that were produced by crossing a semelparous, annual sugar beet with iteroparous, vernalization-requiring wild beet genotypes. The semelparous plants died after reproduction, whereas iteroparous plants reproduced at least twice. All populations segregated for vernalization requirement, seasonal bolting time and the number of reproduction cycles. We found that vernalization requirement co-segregated with the bolting locus B on chromosome 2 and was inherited independently from semel- or iteroparous reproduction. Furthermore, we found that seasonal bolting time is a highly heritable trait (h 2  > 0.84), which is primarily controlled by two major QTL located on chromosome 4 and 9. Late bolting alleles of both loci act in a partially recessive manner and were identified in both iteroparous pollinators. We observed an additive interaction of both loci for bolting delay. The QTL region on chromosome 4 encompasses the floral promoter gene BvFT2, whereas the QTL on chromosome 9 co-localizes with the BR 1 locus, which controls post-winter bolting resistance. Our findings are applicable for marker-assisted sugar beet breeding regarding early bolting to accelerate generation cycles and late bolting to develop bolting-resistant spring and winter beets. Unexpectedly, one population segregated also for dwarf growth that was found to be controlled by a single locus on chromosome 9.

  17. Coordination of Fingertip Forces During Precision Grip in Premanifest Huntington’s Disease

    Science.gov (United States)

    Rao, Ashwini K.; Gordon, Andrew M.; Marder, Karen S.

    2011-01-01

    Precision grip control is important for accurate object manipulation and requires coordination between horizontal (grip) and vertical (load) fingertip forces. Manifest Huntington’s disease (HD) subjects demonstrate excessive and highly variable grip force and delayed coordination between grip and load forces. Because the onset of these impairments is unknown, we examined precision grip control in premanifest HD (pre-HD) subjects. Fifteen pre-HD and 15 age- and sex-matched controls performed the precision grip task in a seated position. Subjects grasped and lifted an object instrumented with a force transducer that measured horizontal grip and vertical load forces. Outcomes were preload time, loading time, maximum grip force, mean static grip force, and variability for all measures. We compared outcomes across groups and correlated grip measures with the Unified Huntington’s Disease Rating Scale and predicted age of onset. Variability of maximum grip force (P disease severity because they were correlated with predicted onset of disease. PMID:21394785

  18. Early Active Rehabilitation After Grip Reconstructive Surgery in Tetraplegia.

    Science.gov (United States)

    Wangdell, Johanna; Bunketorp-Käll, Lina; Koch-Borner, Sabrina; Fridén, Jan

    2016-06-01

    To describe and evaluate the concept of early active rehabilitation after tendon transfer to restore grip function in tetraplegia. Retrospective cohort study. Two nonprofit rehabilitation units in Sweden and Switzerland. All patients with tetraplegia who underwent tendon transfer to restore grip ability during 2009 to 2013 (N=49). Reconstructive tendon transfer surgery with early active rehabilitation to restore grip ability in tetraplegia. Grip and pinch strength, grip ability test, and outcome of prioritized activities. In the 49 surgeries performed, postoperative complications included 2 patients with bleeding and 2 infections related to the surgery. There were no reported ruptures or lengthening of transferred tendons. Within 24 hours after surgery, all 47 patients (100%) with finger flexion reconstruction succeeded to activate their finger flexion. All but 1 patient with reconstructed thumb flexion sucessfully activated their thumb flexion (n=40). Three weeks after surgery, all patients (100%) were able to perform basic activities of daily living, and instrumental activities of daily living were achieved by 74%. One year after surgery, the maximum grip strength in restored finger flexion was on average 6.9kg (range, 1.5-15kg; n=29). The maximum pinch strength in restored thumb flexion was on average 3.7kg (range, 1-20; n=29). On average, grip ability improved from 33 to 101 (n=19) according to the COPM. Prioritized activity limitations, as measured with the COPM, equated to an average of 3.5 steps (2.5 steps preoperatively to 6 steps postoperatively). Patients' perceived satisfaction with this improvement was 4 steps (increasing from 2 steps preoperatively to 6 steps postoperatively). Grip reconstructive surgery followed by early active rehabilitation can be considered a reliable procedure that leads to substantial improvements in grip and pinch strength and activity performance among patients with tetraplegia. Copyright © 2016 American Congress of

  19. Proximity friction reexamined

    International Nuclear Information System (INIS)

    Krappe, H.J.

    1989-01-01

    The contribution of inelastic excitations to radial and tangential friction form-factors in heavy-ion collisions is investigated in the frame-work of perturbation theory. The dependence of the form factors on the essential geometrical and level-density parameters of the scattering system is exhibited in a rather closed form. The conditions for the existence of time-local friction coefficients are discussed. Results are compared to form factors from other models, in particular the transfer-related proximity friction. For the radial friction coefficient the inelastic excitation mechanism seems to be the dominant contribution in peripheral collisions. (orig.)

  20. GRIP GLOBAL HAWK NAVIGATION AND HOUSEKEEPING DATA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Global Hawk Navigation and Housekeeping data was collected from August 15, 2010 to September 24, 2010 during the Genesis and Rapid Intensification Processes...

  1. GRIP DOPPLER AEROSOL WIND LIDAR (DAWN) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Doppler Aerosol WiNd Lidar (DAWN) Dataset was collected by the Doppler Aerosol WiNd (DAWN), a pulsed lidar, which operated aboard a NASA DC-8 aircraft...

  2. GRIP DC-8 NAVIGATION AND HOUSEKEEPING DATA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — This dataset contains aircraft navigational data obtained during the GRIP campaign (15 Aug 2010 - 30 Sep 2010). The NASA DC-8 is outfitted with a navigational...

  3. GRIP DOPPLER AEROSOL WIND LIDAR (DAWN) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Doppler Aerosol WiNd (DAWN), a pulsed lidar, operated aboard a NASA DC-8 aircraft during the Genesis and Rapid Intensification Processes (GRIP) field campaign....

  4. GRIP AIRBORNE SECOND GENERATION PRECIPITATION RADAR (APR-2) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Airborne Second Generation Precipitation Radar (APR-2) dataset was collected from the Second Generation Airborne Precipitation Radar (APR-2), which is a...

  5. GRIP WB-57 NAVIGATION AND HOUSEKEEPING DATA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP WB-57 Navigation and Housekeeping data was collected on flight days occuring between July 13 , 2010 to September 17, 2010 during the Genesis and Rapid...

  6. GRIP DC-8 METEOROLOGICAL MEASUREMENT SYSTEM (MMS) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP DC-8 Meteorological measurement System (MMS) dataset was collected by the Meteorological Measurement System (MMS), which provides high-resolution, accurate...

  7. GRIP BARBADOS/CAPE VERDE RADIOSONDE V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Barbados/Cape Verde radiosonde data set consists of generally two soundings per day (06Z and 12Z) launched from Barbados, and one sounding per day (12Z)...

  8. Basal ganglia mechanisms underlying precision grip force control.

    Science.gov (United States)

    Prodoehl, Janey; Corcos, Daniel M; Vaillancourt, David E

    2009-06-01

    The classic grasping network has been well studied but thus far the focus has been on cortical regions in the control of grasping. Sub-cortically, specific nuclei of the basal ganglia have been shown to be important in different aspects of precision grip force control but these findings have not been well integrated. In this review, we outline the evidence to support the hypothesis that key basal ganglia nuclei are involved in parameterizing specific properties of precision grip force. We review literature from different areas of human and animal work that converges to build a case for basal ganglia involvement in the control of precision gripping. Following on from literature showing anatomical connectivity between the basal ganglia nuclei and key nodes in the cortical grasping network, we suggest a conceptual framework for how the basal ganglia could function within the grasping network, particularly as it relates to the control of precision grip force.

  9. GRIP HIGH-ALTITUDE MMIC SOUNDING RADIOMETER (HAMSR) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP High-Altitude MMIC Sounding Radiometer (HAMSR) dataset was collectd by the High Altitude monolithic microwave integrated Circuit (MMIC) Sounding Radiometer...

  10. Development of a Unified Rock Bolt Model in Discontinuous Deformation Analysis

    Science.gov (United States)

    He, L.; An, X. M.; Zhao, X. B.; Zhao, Z. Y.; Zhao, J.

    2018-03-01

    In this paper, a unified rock bolt model is proposed and incorporated into the two-dimensional discontinuous deformation analysis. In the model, the bolt shank is discretized into a finite number of (modified) Euler-Bernoulli beam elements with the degrees of freedom represented at the end nodes, while the face plate is treated as solid blocks. The rock mass and the bolt shank deform independently, but interact with each other through a few anchored points. The interactions between the rock mass and the face plate are handled via general contact algorithm. Different types of rock bolts (e.g., Expansion Shell, fully grouted rebar, Split Set, cone bolt, Roofex, Garford and D-bolt) can be realized by specifying the corresponding constitutive model for the tangential behavior of the anchored points. Four failure modes, namely tensile failure and shear failure of the bolt shank, debonding along the bolt/rock interface and loss of the face plate, are available in the analysis procedure. The performance of a typical conventional rock bolt (fully grouted rebar) and a typical energy-absorbing rock bolt (D-bolt) under the scenarios of suspending loosened blocks and rock dilation is investigated using the proposed model. The reliability of the proposed model is verified by comparing the simulation results with theoretical predictions and experimental observations. The proposed model could be used to reveal the mechanism of each type of rock bolt in realistic scenarios and to provide a numerical way for presenting the detailed profile about the behavior of bolts, in particular at intermediate loading stages.

  11. Long term consistency of handwriting grip kinetics in adults.

    Science.gov (United States)

    Ghali, Bassma; Mamun, Khondaker A; Chau, Tom

    2014-04-01

    While there is growing interest in clinical applications of handwriting grip kinetics, the consistency of these forces over time is not well-understood at present. In this study, we investigated the short- and long-term intra-participant consistency and inter-participant differences in grip kinetics associated with adult signature writing. Grip data were collected from 20 adult participants using a digitizing tablet and an instrumented pen. The first phase of data collection occurred over 10 separate days within a three week period. To ascertain long-term consistency, a second phase of data collection followed, one day per month over several months. In both phases, data were collected three times a day. After pre-processing and feature extraction, nonparametric statistical tests were used to compare the within-participant grip force variation between the two phases. Participant classification based on grip force features was used to determine the relative magnitude of inter-participant versus intra-participant differences. The misclassification rate for the longitudinal data were used as an indication of long term kinetic consistency. Intra-participant analysis revealed significant changes in grip kinetic features between the two phases for many participants. However, the misclassification rate, on average, remained stable, despite different demarcations of training, and testing data. This finding suggests that while signature writing grip forces may evolve over time, inter-participant kinetic differences consistently exceeds within-participant force changes in the long-term. These results bear implications on the collection, modeling and interpretation of grip kinetics in clinical applications.

  12. Basal Ganglia Mechanisms Underlying Precision Grip Force Control

    OpenAIRE

    Prodoehl, Janey; Corcos, Daniel M.; Vaillancourt, David E.

    2009-01-01

    The classic grasping network has been well studied but thus far the focus has been on cortical regions in the control of grasping. Sub-cortically, specific nuclei of the basal ganglia have been shown to be important in different aspects of precision grip force control but these findings have not been well integrated. In this review we outline the evidence to support the hypothesis that key basal ganglia nuclei are involved in parameterizing specific properties of precision grip force. We revi...

  13. Analysis of WWER 440 SG primary collector bolted joint damage

    International Nuclear Information System (INIS)

    Matocha, K.; Wozniak, J.; Pochman, K.

    1997-01-01

    Bolts made of type CHN35VT-VD stainless steel are being damaged due to stress corrosion cracking. In some cases, after some years of operation cracks appeared also in threaded holes of the primary collector flange due to transgranular stress corrosion cracking of type 08CH18N10T stainless steel. Stress corrosion cracking occurs when an alloy is exposed to a specific aggressive environment at a stress exceeding a critical value. The resistance of both steels to stress corrosion cracking in a high temperature environment was studied using slow strain rate tests of fatigue pre-cracked specimens. Dissolved oxygen or another strong oxidizer must be present to induce stress corrosion cracking of both steels in water environment at about 280 degC containing less than 15 ppm Cl - and 30 ppm SO 4 - . Measures are proposed to improve the reliability of primary collector bolted joints. (M.D.)

  14. AN EXPERIMENTAL STUDY ON THE RELAXATION OF BOLTS

    Directory of Open Access Journals (Sweden)

    Muhammad Abid

    2015-05-01

    Full Text Available Loss of pre-load with time, commonly known as ‘Relaxation’ is an established phenomena. Behaviour of a bolted joint depends upon the pre-load in the bolts in use, not the pre-load introduced by the mechanic. Loss of pre-load is expected due to the many factors such as embedment relaxation, gasket creep, elastic interactions, and vibration loosening or stress relaxation. In a gasketed joint, due to the gasket flexibility, relaxation is always substantial during preliminary passes, as 80 to 100% loss is not uncommon in almost all the bolts, resulting in a dynamic behaviour. Pre-load in a gasketed joint is stabilized and retained to certain extent in the final passes only. In a non-gasketed joint, due to no gasket and no rotation its static behaviour is concluded. This paper highlights the factors affecting the amount of relaxation with time and presents important considerations that can reduce this. Both the short and long term relaxations are recorded and a ‘best fit’ model for relaxation behaviour is derived.

  15. Pyroshock Prediction of Ridge-Cut Explosive Bolts Using Hydrocodes

    Directory of Open Access Journals (Sweden)

    Juho Lee

    2016-01-01

    Full Text Available Pyrotechnic release devices such as explosive bolts are prevalent for many applications due to their merits: high reliability, high power-to-weight ratio, reasonable cost, and more. However, pyroshock generated by an explosive event can cause failures in electric components. Although pyroshock propagations are relatively well understood through many numerical and experimental studies, the prediction of pyroshock generation is still a very difficult problem. This study proposes a numerical method for predicting the pyroshock of a ridge-cut explosive bolt using a commercial hydrocode (ANSYS AUTODYN. A numerical model is established by integrating fluid-structure interaction and complex material models for high explosives and metals, including high explosive detonation, shock wave transmission and propagation, and stress wave propagation. To verify the proposed numerical scheme, pyroshock measurement experiments of the ridge-cut explosive bolts with two types of surrounding structures are performed using laser Doppler vibrometers (LDVs. The numerical analysis results provide accurate prediction in both the time (acceleration and frequency domains (maximax shock response spectra. In maximax shock response spectra, the peaks due to vibration modes of the structures are observed in both the experimental and numerical results. The numerical analysis also helps to identify the pyroshock generation source and the propagation routes.

  16. Grip op werkstress. Mindfulness ontstresst maatschappelijk werkers

    Directory of Open Access Journals (Sweden)

    Jen van Horen

    2014-03-01

    Full Text Available Taking control over work related stress. Mindfulness destresses social workersStress is a major social problem. Due to the increasing workload and the content of the work, social workers are at risk to develop stress (symptoms. The physical and psychological consequences of prolonged stress are serious. By living healthy, optimize working conditions and applying mindfulness, stress can be reduced. Mindfulness is an effective and useful way to reduce stress. It increases the resistance of workers against stress, improves brainfunctions and therefore has a positive effect on the performance. These effects are great, but they are still weakly methodologically substantiated. A pilot project within the youthcare though, was enthusiastically received and proves to be effective against stress symptoms. The exercises that are part of this pilot fit well with the needs of employees. For organizations mindfulnesstrainings are a time-and cost-effective way of structural stress prevention.Grip op werkstress. Mindfulness ontstresst maatschappelijk werkersStress is een omvangrijk maatschappelijk probleem. Door de toenemende werkdruk en de inhoud van het werk zijn maatschappelijk werkers een risicogroep om stress en stressklachten te ontwikkelen. De fysieke en psychische gevolgen die langdurige stress met zich meebrengt zijn ernstig. Door gezond te leven, de arbeidsomstandigheden te optimaliseren en mindfulness toe te passen kan stress terug worden gedrongen. Mindfulness is een effectieve en bruikbare manier om stress te verminderen. Het vergroot de weerbaarheid van werknemers tegen stress, het verbetert de hersenwerking en heeft daardoor een positief effect op het functioneren. Grote effecten dus, maar wel nog methodologisch zwak onderbouwd. Een pilot binnen de jeugdzorg op het gebied van mindfulness is enthousiast ontvangen en blijkt effectief tegen stressklachten. De oefeningen die onderdeel uitmaken van deze pilot sluiten goed aan bij de behoeften van

  17. [Diagnostic ability of power measurement of different grip forms for distal median nerve lesion].

    Science.gov (United States)

    Wachter, N; Mentzel, M; Krischak, G; Häderer, C; Gülke, J

    2018-03-01

    Peripheral lesions of the median nerve cause characteristic changes of the grip function of the hand. For evaluating grip force changes, measurement by dynamometers (JAMAR dynamometer and pinch dynamometer) is of high relevance. In this study the ability of grip force measurements of different grip forms was evaluated to discriminate between a simulated median nerve lesion and healthy subjects. In 21 healthy subjects, the grip force of power grip was measured by the JAMAR dynamometer at the second stage including measurement of force at the fingertips and the thenar by a sensor glove. With a pinch dynamometer the power of palmar abduction, precision grip, pincer grip and pinch grip was determined. Measurements were performed with and without median nerve block at the wrist. In power grip of the JAMAR dynamometer at the second stage a significant reduction of the grip force of 13.4% was found (p power distribution between the fingers D2-D5 did not change with median nerve block. The most relevant reduction of grip force in median nerve block compared with the healthy control was measured in palmar abduction (72.1%, p block there was a limited relevance of the measurement of the power grip and force distribution at the fingers by the JAMAR dynamometer. However, the best distinction was observed by dynamometric measurement of other grips than power grip, such as palmar abduction, precision grip, pincer grip and pinch grip. The results could be relevant for the clinical diagnostics and rehabilitation of median nerve lesion, complementing the widespread measurement of the power grip by other grip forms.

  18. The research on delayed fracture behavior of high-strength bolts in steel structure

    Science.gov (United States)

    Li, Guo dong; Li, Nan

    2017-07-01

    High-strength bolts have been widely used in power plants. However, the high-strength bolts which being employed in pumping station, steel structure and pipeline anti-whip structure have been found delayed fracture for many times in a power plant, this will affect the reliability of steel fracture and bring blow risk caused by falling objects. The high-strength bolt with delayed fracture was carried out fracture analysis, metallurgical analysis, chemical analysis, mechanical analysis, as well as bolts installation analysis, it can be comprehensively confirmed that the direct cause of high-strength bolts delayed fracture is the stress corrosion, and the root cause of high-strength bolts delayed fracture should be the improper installation at the initial and the imperfect routine anti-corrosion maintenance.

  19. Estimation on the clamping force of high strength bolt by temperature parameter

    International Nuclear Information System (INIS)

    Nah, Hwan-Seon; Kim, Kang-Seok; Lee, Hyeon-Ju; Kim, Woo-Bum

    2009-01-01

    In case of Korean nuclear power plant, the field design of bolted connection for steel structures has been changed from high strength hexagon bolt to torque shear bolt. The torque control method is mainly used as a clamping method of high strength bolt at construction site. However the torque coefficient affects the design strength in tension on the process of tightening by torque control. This is why it is obscure to assume quantitatively the direct tension induced into bolt. The determinant factor affected on the clamping force is ambient temperature as Korean standard B 2819 indicated. This study was planned to assess the expected clamping force on two kinds of high strength bolts considering temperature ranged from -10degC to 50degC. From test data subjected to temperature parameters, the equation to estimate the clamping force was extracted by regression analysis. (author)

  20. Biomechanical analysis of the circular friction hand massage.

    Science.gov (United States)

    Ryu, Jeseong; Son, Jongsang; Ahn, Soonjae; Shin, Isu; Kim, Youngho

    2015-01-01

    A massage can be beneficial to relieve muscle tension on the neck and shoulder area. Various massage systems have been developed, but their motions are not uniform throughout different body parts nor specifically targeted to the neck and shoulder areas. Pressure pattern and finger movement trajectories of the circular friction hand massage on trapezius, levator scapulae, and deltoid muscles were determined to develop a massage system that can mimic the motion and the pressure of the circular friction massage. During the massage, finger movement trajectories were measured using a 3D motion capture system, and finger pressures were simultaneously obtained using a grip pressure sensor. Results showed that each muscle had different finger movement trajectory and pressure pattern. The trapezius muscle experienced a higher pressure, longer massage time (duration of pressurization), and larger pressure-time integral than the other muscles. These results could be useful to design a better massage system simulating human finger movements.

  1. The influence of the crimp and slope grip position on the finger pulley system.

    Science.gov (United States)

    Schöffl, I; Oppelt, K; Jüngert, J; Schweizer, A; Neuhuber, W; Schöffl, V

    2009-09-18

    In this study the influence of the grip position (crimp grip vs. slope grip position) on the pulley system of the finger was investigated. For this purpose 21 cadaver finger (11 hands, 10 donors) were fixed into an isokinetic loading device. Nine fingers were loaded in the slope grip position and 12 fingers in the crimp grip position. The forces in the flexor tendons and at the fingertip were recorded. A rupture of the A4 pulley occurred most often in the crimp grip position (50%) but did not occur in the slope grip position, in which alternative events were the most common (67%). The forces in the deep flexor tendon (FDP) (slope grip: 371 N, crimp grip: 348 N) and at the fingertip (slope grip: 105 N, crimp grip: 161 N) were not significantly different between the 2 finger positions, but the forces acting on the pulleys were higher in the crimp grip position (A2 pulley: 287 N, A4 pulley: 226 N) than in the slope grip position (A2 pulley: 121 N, A4 pulley: 103 N). The crimp grip position may be the main cause for A4 pulley ruptures but the slope grip position may be hazardous for other injuries as the forces recorded in the flexor tendons and at the fingertip were comparable at the occurrence of a terminal event.

  2. TESTS ON 10.9 BOLTS UNDER COMBINED TENSION AND SHEAR

    Directory of Open Access Journals (Sweden)

    Anne Katherine Kawohl

    2016-04-01

    Full Text Available Prior investigations of the load-bearing capacity of bolts during fire have shown differing behaviour between bolts that have been loaded by shear or by tensile loads. A combination of the two loads has not yet been examined under fire conditions. This paper describes a series of tests on high-strength bolts of property class 10.9 both during and after fire under a combined shear and tensile load.

  3. Influence of Thread Root Radius on Maximum Local Stresses at Large Diameter Bolts under Axial Loading

    Directory of Open Access Journals (Sweden)

    Cojocaru Vasile

    2014-06-01

    Full Text Available In the thread root area of the threaded bolts submitted to axial loading occur local stresses, higher that nominal stresses calculated for the bolts. These local stresses can generate failure and can reduce the fatigue life of the parts. The paper is focused on the study of the influence of the thread root radius on the maximum local stresses. A large diameter trapezoidal bolt was subjected to a static analysis (axial loading using finite element simulation.

  4. Reinforcement of Underground Excavation with Expansion Shell Rock Bolt Equipped with Deformable Component

    Directory of Open Access Journals (Sweden)

    Korzeniowski Waldemar

    2017-03-01

    Full Text Available The basic type of rock mass reinforcement method for both preparatory and operational workings in underground metal ore mines, both in Poland and in different countries across the world, is the expansion shell or adhesive-bonded rock bolt. The article discusses results of static loading test of the expansion shell rock bolts equipped with originally developed deformable component. This component consists of two profiled rock bolt washers, two disk springs, and three guide bars. The disk spring and disk washer material differs in stiffness. The construction materials ensure that at first the springs under loading are partially compressed, and then the rock bolt washer is plastically deformed. The rock bolts tested were installed in blocks simulating a rock mass with rock compressive strength of 80 MPa. The rock bolt was loaded statically until its ultimate loading capacity was exceeded. The study presents the results obtained under laboratory conditions in the test rig allowing testing of the rock bolts at their natural size, as used in underground metal ore mines. The stress-strain/displacement characteristics of the expansion shell rock bolt with the deformable component were determined experimentally. The relationships between the geometric parameters and specific strains or displacements of the bolt rod were described, and the percentage contribution of those values in total displacements, resulting from the deformation of rock bolt support components (washer, thread and the expansion shell head displacements, were estimated. The stiffness of the yielded and stiff bolts was empirically determined, including stiffness parameters of every individual part (deformable component, steel rod. There were two phases of displacement observed during the static tension of the rock bolt which differed in their intensity.

  5. An Investigation on the Ultimate Strength of Cold-Formed Steel Bolted Connections

    Directory of Open Access Journals (Sweden)

    N. Konkong

    2017-08-01

    Full Text Available This paper presents experimental results and finite element analysis of the cold-formed steel bolted connection under shear loading. Experiments are conducted to study the ultimate behaviors, such as ultimate strength and failure mode of connections. The samples were fabricated into three different groups, single bolted, double bolted and quadruple bolted connection. Material properties were determined by tensile coupon testing. Bearing failure modes were detected in the bolted connection tests. The ultimate capacities were compared with the nominal strengths calculated using the AISI (2012. The comparisons show that the nominal strength parameters predicted by this specification is conservative. The finite element analysis shell elements were used to model the cold-formed steel plate while solid elements were used to model the bolted fastenings for the purpose of studying the structural behavior of bolted connections. Material nonlinearities, contact problem and geometry nonlinearities analysis are carried out in order to predict ultimate strength and failure mode of connections. The results show that the proposed model accurately represents the failure mode and ultimate strength of bolted connection, as determined from experimental investigation. The new factor for type of bearing connection has a good agreement with the tested bearing strength of bolt connection.

  6. Post-Service Examination of PWR Baffle Bolts, Part I. Examination and Test Plan

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, Keith J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sokolov, Mikhail A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gussev, Maxim N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-04-30

    In support of extended service and current operations of the US nuclear reactor plants, the Oak Ridge National Laboratory (ORNL), through the Department of Energy (DOE), Light Water Reactor Sustainability (LWRS) Program, is coordinating with Ginna Nuclear Power Plant, The Westinghouse Electric Company, LLC, and ATI Consulting, the selective procurement of baffle bolts that were withdrawn from service in 2011 and currently stored on site at Ginna. The goal of this program is to perform detailed microstructural and mechanical property characterization of baffle former bolts following in-service exposures. This report outlines the selection criteria of the bolts and the techniques to be used in this study. The bolts available are the original alloy 347 steel fasteners used in holding the baffle plates to the baffle former structures within the lower portion of the pressurized water reactor vessel. Of the eleven possible bolts made available for this work, none were identified to have specific damage. The bolts, however, did show varying levels of breakaway torque required in their removal. The bolts available for this study varied in peak fluence (highest dose within the head of the bolt) between 9.9 and 27.8x1021 n/cm2 (E>1MeV). As no evidence for crack initiation was determined for the available bolts from preliminary visual examination, two bolts with the higher fluence values were selected for further post-irradiation examination. The two bolts showed different breakaway torque levels necessary in their removal. The information from these bolts will be integral to the LWRS program initiatives in evaluating end of life microstructure and properties. Furthermore, valuable data will be obtained that can be incorporated into model predictions of long-term irradiation behavior and compared to results obtained in high flux experimental reactor conditions. The two bolts selected for the ORNL study will be shipped to Westinghouse with bolts of

  7. A Synthetic Phased Array Surface Acoustic Wave Sensor for Quantifying Bolt Tension

    Directory of Open Access Journals (Sweden)

    Rasim Guldiken

    2012-09-01

    Full Text Available In this paper, we report our findings on implementing a synthetic phased array surface acoustic wave sensor to quantify bolt tension. Maintaining proper bolt tension is important in many fields such as for ensuring safe operation of civil infrastructures. Significant advantages of this relatively simple methodology is its capability to assess bolt tension without any contact with the bolt, thus enabling measurement at inaccessible locations, multiple bolt measurement capability at a time, not requiring data collection during the installation and no calibration requirements. We performed detailed experiments on a custom-built flexible bench-top experimental setup consisting of 1018 steel plate of 12.7 mm (½ in thickness, a 6.4 mm (¼ in grade 8 bolt and a stainless steel washer with 19 mm (¾ in of external diameter. Our results indicate that this method is not only capable of clearly distinguishing properly bolted joints from loosened joints but also capable of quantifying how loose the bolt actually is. We also conducted detailed signal-to-noise (SNR analysis and showed that the SNR value for the entire bolt tension range was sufficient for image reconstruction.

  8. Evaluation of long-term relaxation for high-strength bolted connections

    International Nuclear Information System (INIS)

    Nah, H. S.; Lee, H. J.; Kim, K. S.

    2010-01-01

    It is general that the clamping forces of high-strength bolts diminish within a certain time period after the initial clamping force. In case that special treatments are applied on a faying surface, the clamping force is relaxed severely. Tests were conducted for slip critical joints subjected to various faying surface parameters. The candidates for bolt were two kinds: Korean Standard and American Standard. Relaxation occurred for slip resistant joints with an uncoated surface that had been shot-blasted, cleaned, milled or rusted. In case of ASTM hexagon bolts, the initial clamping force dropped from 7.9% to 13.6% after 1, 000 hours while relaxation ratio was the range from 8.7% to 15.4% for KS bolts. For ASTM hexagon bolt joints with a 5 mil thick zinc coating, the clamping force of the bolts decreased 15.0%, while relaxation ratio was 12.85% for KS bolts. For 4.9 mil thick red lead painted treatment, the relaxation ratio was 18.7% for ASTM hexagon bolt, 34.9% for KS bolts. Regardless of faying surface treatments, the first week charged at least 86% of total relaxation from this test. (authors)

  9. Laboratory testing of a long expansion rock bolt support for energy-absorbing applications

    Directory of Open Access Journals (Sweden)

    Skrzypkowski Krzysztof

    2018-01-01

    Full Text Available The main purpose of rock support and reinforcement in underground mining is to maintain excavations safe and open for their intended lifespan. The basic type of rock mass reinforcement method both in ore and hard coal mining is rock bolt support. Very often, existing bolt support systems are not always capable of providing a reliable controlled performance. Therefore, in recent years energy-absorbing bolts which are exposed to dynamic loading, for example from rock burst caused by high rock stresses, earthquakes, or blasting have appeared. In this article particular attention was paid to short and long expansion bolts. Quasi-static tests of expansion bolts were carried out at the laboratory test facility in simulated mining conditions, especially for the KGHM Polska Miedź S.A. mines. In the underground mines of the Legnica-Głogów Copper District (LGOM the main way to protect the room excavation is rock bolt support with a length from 1.2 m to 2.6 m. Rock bolt support longer than 2.6 m is considered as additional support of excavations and is increasingly being used to reinforce the roofs. The comparisons of energy-absorbing short and long expansion bolts with a length of 1.8m, 3.6m and 5.2m were presented. In addition, for elastic and plastic range of each bolts were determined.

  10. Laboratory testing of a long expansion rock bolt support for energy-absorbing applications

    Science.gov (United States)

    Skrzypkowski, Krzysztof

    2018-01-01

    The main purpose of rock support and reinforcement in underground mining is to maintain excavations safe and open for their intended lifespan. The basic type of rock mass reinforcement method both in ore and hard coal mining is rock bolt support. Very often, existing bolt support systems are not always capable of providing a reliable controlled performance. Therefore, in recent years energy-absorbing bolts which are exposed to dynamic loading, for example from rock burst caused by high rock stresses, earthquakes, or blasting have appeared. In this article particular attention was paid to short and long expansion bolts. Quasi-static tests of expansion bolts were carried out at the laboratory test facility in simulated mining conditions, especially for the KGHM Polska Miedź S.A. mines. In the underground mines of the Legnica-Głogów Copper District (LGOM) the main way to protect the room excavation is rock bolt support with a length from 1.2 m to 2.6 m. Rock bolt support longer than 2.6 m is considered as additional support of excavations and is increasingly being used to reinforce the roofs. The comparisons of energy-absorbing short and long expansion bolts with a length of 1.8m, 3.6m and 5.2m were presented. In addition, for elastic and plastic range of each bolts were determined.

  11. Influence of crustal stress on gob-side roadway supported by rock bolt

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; Zhang, S.; Hou,C.; Wang, P.; Zhang, M.; Yuan, Q.; Pang, J.; Li, H. [China University of Mining and Technology, Xuzhou (China). Dept. of Mining Engineering

    1999-07-01

    On the basis of numerical simulation, the influence of crustal stress on roof-bolted gob-side roadway is discussed. The discussion includes the perimeter convergence and deep displacement of roadway, the arrangement of rock bolt for gob-side roadway, and the width of support pillar. The research proves the feasibility of supporting gob-side roadway by rock bolt from the angle of crustal stress. The results can provide a reliable foundation for designing the scientific and reasonable parameters of bolt supporting. 2 refs., 6 figs.

  12. Metallurgical examinations update of baffle bolts removed from operating French PWR. Microstructural investigations of a baffle to former bolt located on a high level of the internal structures

    International Nuclear Information System (INIS)

    Panait, C.; Fargeas, E.; Miloudi, S.; Moulart, P.; Tommy-Martin, M.; Monteil, N.; Pokor, C.

    2015-01-01

    This paper presents the microstructural investigations conducted on a cracked baffle to former bolt extracted from an upper former level of the internal structures of a French Pressurized Water Reactor (PWR). Extensive microstructural investigations using Light Microscopy, Scanning Electron Microscopy and Transmission Electron Microscopy (TEM) have been conducted to understand the degradation mechanisms of this bolt. TEM investigations have revealed neutron irradiation damage in the microstructure of the bolt such as Frank loops and cavities and/or bubbles. The number of features per unit volume as a function of diameter was determined in the head and in the shank of the bolt. The obtained results are relatively similar to those obtained for other damaged bolts extracted from PWR-type reactors and irradiated in similar conditions (dose and temperature). The irradiation damage has induced an evolution of the mechanical properties (hardening of the material), as revealed by the hardness measurements along the bolt, with a higher average value in the head (400 HV), compared to the shank (15 mm under the head), about 340 HV. The metallurgical investigations have confirmed that this bolt was damaged by Irradiation Assisted Stress Corrosion Cracking (IASCC)

  13. Power grip force is modulated in repeated elbow movement.

    Science.gov (United States)

    Gao, Fan

    2012-01-01

    The objective of this study was to quantitatively investigate the modulation of power grip force under repeated elbow movement and its relation to muscle cocontraction and potential risk of developing cumulative trauma disorders (CTD). Thirteen right-handed participants without any neuromuscular disorders were recruited. Participants were instructed to hold a digital dynamometer in the hand with three levels of grip forces (20%, 40% and 60% of the maximum grip force) and perform repeated arm movement in the sagittal plane at three speeds (slow, self-paced and fast) with the upper arm voluntarily held by side by the participant. With the increase of motion rate and target force level, the grip force fluctuation, finger flexor muscle activities, elbow muscles cocontraction and apparent stiffness were significantly increased (p movement be avoided as much as possible in the workplace. Power grip is usually accompanied with arm movement in workplaces and the increased physical demand might result in higher muscle activities and potentially higher risk of repetitive musculoskeletal injuries.

  14. Polymer friction Molecular Dynamics

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, Vladimir N.; Persson, Bo N. J.

    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: a) polymer sliding against a hard substrate, and b) polymer sliding on polymer. In the first setup the shear stresses are relatively...... independent of molecular length. For polymer sliding on polymer the friction is significantly larger, and dependent on the molecular chain length. In both cases, the shear stresses are proportional to the squeezing pressure and finite at zero load, indicating an adhesional contribution to the friction force....

  15. Effect of toothbrush grip on plaque removal during manual toothbrushing in children.

    Science.gov (United States)

    Sharma, Sarika; Yeluri, Ramakrishna; Jain, Amit A; Munshi, Autar K

    2012-01-01

    Toothbrushing is fundamental to oral hygiene. Children differ in manual dexterity and their grip on toothbrushes. We videotaped toothbrushing sessions and observed the grip type, duration of brushing, and brushing technique used among 100 children aged 8-12 years. We then investigated the association between grip type and plaque removal, using plaque scores obtained at various time points. We further examined the effect on plaque scores of standardizing both brushing technique and duration among the same participants. The most common grip was the distal oblique, followed by the oblique; the spoon and precision grips were rare, and no child used a power grip. Mean brushing duration for most children was 1.43 ± 0.85 min, and the most common brushing technique was horizontal scrubbing. We conclude that grip preference is inherent and that the distal oblique grip was better than the oblique grip in removing plaque.

  16. Monitoring of Pre-Load on Rock Bolt Using Piezoceramic-Transducer Enabled Time Reversal Method.

    Science.gov (United States)

    Huo, Linsheng; Wang, Bo; Chen, Dongdong; Song, Gangbing

    2017-10-27

    Rock bolts ensure structural stability for tunnels and many other underground structures. The pre-load on a rock bolt plays an important role in the structural reinforcement and it is vital to monitor the pre-load status of rock bolts. In this paper, a rock bolt pre-load monitoring method based on the piezoceramic enabled time reversal method is proposed. A lead zirconate titanate (PZT) patch transducer, which works as an actuator to generate stress waves, is bonded onto the anchor plate of the rock bolt. A smart washer, which is fabricated by sandwiching a PZT patch between two metal rings, is installed between the hex nut and the anchor plate along the rock bolt. The smart washer functions as a sensor to detect the stress wave. With the increase of the pre-load values on the rock bolt, the effective contact surface area between the smart washer and the anchor plate, benefiting the stress wave propagation crossing the contact surface. With the help of time reversal technique, experimental results reveal that the magnitude of focused signal clearly increases with the increase of the pre-load on a rock bolt before the saturation which happens beyond a relatively high value of the pre-load. The proposed method provides an innovative and real time means to monitor the pre-load level of a rock bolt. By employing this method, the pre-load degradation process on a rock bolt can be clearly monitored. Please note that, currently, the proposed method applies to only new rock bolts, on which it is possible to install the PZT smart washer.

  17. Monitoring of Pre-Load on Rock Bolt Using Piezoceramic-Transducer Enabled Time Reversal Method

    Directory of Open Access Journals (Sweden)

    Linsheng Huo

    2017-10-01

    Full Text Available Rock bolts ensure structural stability for tunnels and many other underground structures. The pre-load on a rock bolt plays an important role in the structural reinforcement and it is vital to monitor the pre-load status of rock bolts. In this paper, a rock bolt pre-load monitoring method based on the piezoceramic enabled time reversal method is proposed. A lead zirconate titanate (PZT patch transducer, which works as an actuator to generate stress waves, is bonded onto the anchor plate of the rock bolt. A smart washer, which is fabricated by sandwiching a PZT patch between two metal rings, is installed between the hex nut and the anchor plate along the rock bolt. The smart washer functions as a sensor to detect the stress wave. With the increase of the pre-load values on the rock bolt, the effective contact surface area between the smart washer and the anchor plate, benefiting the stress wave propagation crossing the contact surface. With the help of time reversal technique, experimental results reveal that the magnitude of focused signal clearly increases with the increase of the pre-load on a rock bolt before the saturation which happens beyond a relatively high value of the pre-load. The proposed method provides an innovative and real time means to monitor the pre-load level of a rock bolt. By employing this method, the pre-load degradation process on a rock bolt can be clearly monitored. Please note that, currently, the proposed method applies to only new rock bolts, on which it is possible to install the PZT smart washer.

  18. In situ ultrasonic examination of high-strength steam generator support bolts

    International Nuclear Information System (INIS)

    Jusino, A.

    1985-01-01

    Currently employed high-strength steam generator support bolting material (designed prior to ASME Section III Part NF or Component Supports), 38.1 mm in diameter, in combination with high preloads are susceptible to stress corrosion cracking because of the relatively low stress corrosion resistance (K/sub ISCC/) properties. These bolts are part of the pressurized water reactor steam generator supports at the integral support pads (three per steam generator, with each pad housing six, eight, or ten bolts depending on the design). The US Nuclear Regulatory Commission concerns for high-strength bolting were identified in NUREG-0577, ''Potential for Low Fracture Toughness and Laminar Tearing in PWR Steam Generator and Reactor Coolant Pump Supports,'' which was issued for comment on unresolved safety issue A-12. Subsequently, the bolting issues were addressed in generic issue B29. One of the issues deals specifically with high-strength bolting materials, which are vulnerable to stress corrosion cracking. A Westinghouse Owners Group funded program was established to develop in situ ultrasonic examination techniques to determine steam generator support bolting integrity at the head-to-shank and first-thread locations. This program was established in order to determine bolting integrity in place. Ultrasonic techniques were developed for both socket-head and flat-head bolt configurations. As a result of this program, in situ ultrasonic examination techniques were developed for examination of PWR steam generator support bolts. By employing these techniques utilities will be able to ensure the integrity of this in-place bolting without incurring the costs previously experienced during removal for surface examinations

  19. Friction stir welding tool

    Science.gov (United States)

    Tolle,; Charles R. , Clark; Denis E. , Barnes; Timothy, A [Ammon, ID

    2008-04-15

    A friction stir welding tool is described and which includes a shank portion; a shoulder portion which is releasably engageable with the shank portion; and a pin which is releasably engageable with the shoulder portion.

  20. Paediatric treadmill friction injuries.

    Science.gov (United States)

    Jeremijenko, Luke; Mott, Jonathan; Wallis, Belinda; Kimble, Roy

    2009-05-01

    The aim of this study was to report on the severity and incidence of children injured by treadmills and to promote the implementation of safety standards. This retrospective review of children with treadmill friction injuries was conducted in a single tertiary-level burns centre in Australia between January 1997 and June 2007. The study revealed 37 children who sustained paediatric treadmill friction injuries. This was a presentation of 1% of all burns. Thirty-three (90%) of the injuries occurred in the last 3.5 years (January 2004 to June 2007). The modal age was 3.2 years. Thirty-three (90%) injuries were either full thickness or deep partial friction burns. Eleven (30%) required split thickness skin grafts. Of those who became entrapped, 100% required skin grafting. This study found that paediatric treadmill friction injuries are severe and increasing in incidence. Australian standards should be developed, implemented and mandated to reduce this preventable and severe injury.

  1. Dynamic pressure measurement of cartridge operated vole captive bolt devices.

    Science.gov (United States)

    Frank, M; Philipp, K P; Franke, E; Frank, N; Bockholdt, B; Grossjohann, R; Ekkernkamp, A

    2009-01-10

    Vole captive bolt devices are powder actuated spring guns that are used as a pest control mean. After having triggered the explosion of the blank cartridge by touching a metal ring around the muzzle, the vole is killed by the massive propulsion of the gas jet. Improper use and recklessness while handling these devices may cause severe injuries with the hand of the operator at particular risk. Currently, there are no experimental investigations on the ballistic background of these devices. An experimental test set-up was designed for measurement of the firing pressure and the dynamic force of the gas jet of a vole captive bolt device. Therefore, a vole captive bolt device was prepared with a pressure take-off channel and a piezoelectric transducer for measurement of the firing pressure. For measurement of the dynamic impact force of the gas jet an annular quartz force sensor was installed on a test bench. Each three simultaneous measurements of the cartridges' firing pressure and the dynamic force of the blast wave were taken at various distances between muzzle and load washer. The maximum gas pressure in the explosion chamber was up to 1100 bar. The shot development over time showed a typical gas pressure curve. Flow velocity of the gas jet was up to 2000 m/s. The maximum impact force of the gas jet at the target showed a strong inverse ratio to the muzzle's distance and was up to 11,500 N for the contact shot distance. Energy density of the gas jet for the close contact shot was far beyond the energy density required for skin penetration. The unique design features (short tube between cartridge mouth and muzzle and narrow diameter of the muzzle) of these gadgets are responsible for the high firing pressure, velocity and force of the gas jet. These findings explain the trauma mechanics of the extensive tissue damage observed in accidental shots of these devices.

  2. Stress evaluation of baffle former bolt for IASCC failure prediction

    International Nuclear Information System (INIS)

    Matsubara, T.; Tsutsui, T.; Kamei, Y.; Kitsu, M.

    2011-01-01

    Baffle structure in PWRs Reactor is quite important assembly for the core safety, and Baffle Former Bolts (BFBs) are fastener members for maintaining Baffle structure. It has been reported worldwide that some of BFBs were cracked due to IASCC (Irradiation Assisted Stress Corrosion Cracking) because BFBs are located at core region under severe environments, high neutron flux, high temperature and high stress. According to the material studies of IASCC on austenitic stainless steel, a crack initiation of IASCC is strongly related with the stress and the neutron fluence. For this reason, it is very important for IASCC failure prediction to simulate the stress of BFBs. However, the stress of BFBs are considered to be influenced by several factors and to be changed complexly as operational time increases, by irradiation creep of Bolt itself, swelling of Baffle structure, and so on. Therefore, it is difficult to estimate the stress histories of BFBs (Bolt stress as a function of operational time) precisely. Then, the author has developed the calculation method of the stress histories of BFBs considering irradiation effects (swelling and irradiation creep). In this method, the stress histories of BFBs are calculated by combining two kinds of FE models, Global model (modeled whole Baffle structure which consists of Baffle plates, Former plates and Core Barrel) and Local model (modeled around BFB finely). The whole Baffle structure deformation changes as a function of heat, swelling and irradiated creep are calculated by Global model, and the stress histories of BFBs are calculated by Local model using the outputs (deformations on driving nodes) of Global model. In the FE analysis of Local model, the stress of BFBs are calculated considering irradiation effects and elastic-plastic characteristics depending on neutron fluence, so this method enables to calculate precisely the stress of extreme small area of BFBs surface. This paper shows the outline of the calculation method

  3. Skin tribology: Science friction?

    OpenAIRE

    Heide, E. van der; Zeng, X.; Masen, M.A.

    2013-01-01

    The application of tribological knowledge is not just restricted to optimizing mechanical and chemical engineering problems. In fact, effective solutions to friction and wear related questions can be found in our everyday life. An important part is related to skin tribology, as the human skin is frequently one of the interacting surfaces in relative motion. People seem to solve these problems related to skin friction based upon a trial-and-error strategy and based upon on our sense for touch....

  4. Topological complexity of frictional interfaces: friction networks

    Directory of Open Access Journals (Sweden)

    H. O. Ghaffari

    2012-03-01

    Full Text Available Through research conducted in this study, a network approach to the correlation patterns of void spaces in rough fractures (crack type II was developed. We characterized friction networks with several networks characteristics. The correlation among network properties with the fracture permeability is the result of friction networks. The revealed hubs in the complex aperture networks confirmed the importance of highly correlated groups to conduct the highlighted features of the dynamical aperture field. We found that there is a universal power law between the nodes' degree and motifs frequency (for triangles it reads T(kkβ (β ≈ 2 ± 0.3. The investigation of localization effects on eigenvectors shows a remarkable difference in parallel and perpendicular aperture patches. Furthermore, we estimate the rate of stored energy in asperities so that we found that the rate of radiated energy is higher in parallel friction networks than it is in transverse directions. The final part of our research highlights 4 point sub-graph distribution and its correlation with fluid flow. For shear rupture, we observed a similar trend in sub-graph distribution, resulting from parallel and transversal aperture profiles (a superfamily phenomenon.

  5. Comparative study of maximum isometric grip strength in different sports

    OpenAIRE

    Noé Gomes Borges Junior; Susana Cristina Domenech; Jonathan Ache Dias; Affonso Celso Kulevicz da Silva; Yoshimasa Sagawa Junior

    2009-01-01

    http://dx.doi.org/10.5007/1980-0037.2009v11n3p292   The objective of this study was to compare maximum isometric grip strength (Fmax)between different sports and between the dominant (FmaxD) and non-dominant (FmaxND) hand. Twenty-nine male aikido (AI), jiujitsu (JJ), judo (JU) and rowing (RO) athletes and 21non-athletes (NA) participated in the study. The hand strength test consisted of maintainingmaximum isometric grip strength for 10 seconds using a hand dynamometer. The position of...

  6. MADS-box genes and gibberellins regulate bolting in lettuce (Lactuca sativa L.

    Directory of Open Access Journals (Sweden)

    Yingyan Han

    2016-12-01

    Full Text Available Bolting in lettuce is promoted by high temperature and bolting resistance is of great economic importance for lettuce production. But how bolting is regulated at the molecular level remains elusive. Here, a bolting resistant line S24 and a bolting sensitive line S39 were selected for morphological, physiological, transcriptomic and proteomic comparisons. A total of 12204 genes were differentially expressed in S39 vs S24. Line S39 was featured with larger leaves, higher levels of chlorophyll, soluble sugar, anthocyanin and auxin, consistent with its up-regulation of genes implicated in photosynthesis, oxidation-reduction and auxin actions. Proteomic analysis identified 30 differentially accumulated proteins in lines S39 and S24 upon heat treatment, and 19 out of the 30 genes showed differential expression in the RNA-Seq data. Exogenous gibberellins (GA treatment promoted bolting in both S39 and S24, while 12 flowering promoting MADS-box genes were specifically induced in line S39, suggesting that although GA regulates bolting in lettuce, it may be the MADS-box genes, not GA, that plays a major role in differing the bolting resistance between these two lettuce lines.

  7. MADS-Box Genes and Gibberellins Regulate Bolting in Lettuce (Lactuca sativaL.).

    Science.gov (United States)

    Han, Yingyan; Chen, Zijing; Lv, Shanshan; Ning, Kang; Ji, Xueliang; Liu, Xueying; Wang, Qian; Liu, Renyi; Fan, Shuangxi; Zhang, Xiaolan

    2016-01-01

    Bolting in lettuce is promoted by high temperature and bolting resistance is of great economic importance for lettuce production. But how bolting is regulated at the molecular level remains elusive. Here, a bolting resistant line S24 and a bolting sensitive line S39 were selected for morphological, physiological, transcriptomic and proteomic comparisons. A total of 12204 genes were differentially expressed in S39 vs. S24. Line S39 was featured with larger leaves, higher levels of chlorophyll, soluble sugar, anthocyanin and auxin, consistent with its up-regulation of genes implicated in photosynthesis, oxidation-reduction and auxin actions. Proteomic analysis identified 30 differentially accumulated proteins in lines S39 and S24 upon heat treatment, and 19 out of the 30 genes showed differential expression in the RNA-Seq data. Exogenous gibberellins (GA) treatment promoted bolting in both S39 and S24, while 12 flowering promoting MADS-box genes were specifically induced in line S39, suggesting that although GA regulates bolting in lettuce, it may be the MADS-box genes, not GA, that plays a major role in differing the bolting resistance between these two lettuce lines.

  8. EVALUATION OF ROOF BOLTING REQUIREMENTS BASED ON IN-MINE ROOF BOLTER DRILLING

    Energy Technology Data Exchange (ETDEWEB)

    Syd S. Peng

    2003-07-15

    Roof bolting is the most popular method for underground openings in the mining industry, especially in the bedded deposits such as coal, potash, salt etc. In fact, all U.S. underground coal mine entries are roof-bolted as required by law. However, roof falls still occur frequently in the roof bolted entries. The two possible reasons are: the lack of knowledge of and technology to detect the roof geological conditions in advance of mining, and lack of roof bolting design criteria for modern roof bolting systems. This research is to develop a method for predicting the roof geology and stability condition in real time during roof bolting operation. Based on such information, roof bolting design criteria for modern roof bolting systems will be developed for implementation in real time. In this quarter, the field, theoretical and programming works have been performed toward achieving the research goals set in the proposal. The selected site and the field testing plan enabled us to test all three aspects of roof geological features. The development of the data interpretation methodologies and the geology mapping computer program have also been preceding well.

  9. Laboratory evaluation of alloy X-750 clevis bolts removed from D.C. cook unit 1

    International Nuclear Information System (INIS)

    Hyres, J.; Xu, H.; Kalchik, K.; Thompson, G.

    2015-01-01

    This paper summarizes the results of the laboratory evaluation performed by Babcock and Wilcox on Alloy X-750 clevis bolts removed from the Lower Radial Support System (LRSS) at D.C. Cook Unit 1. A total of 29 clevis bolts - 16 broken and 13 intact - were provided for laboratory analysis and testing to document the extent of degradation, evaluate the integrity of the intact bolts, and identify the bolt degradation/failure mechanism(s). The laboratory work scope included visual and stereo-visual examinations of all bolts. Based on the results of these examinations, four bolts - two broken and two intact - were selected for more detailed analysis/testing, including Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), optical metallography, microhardness, chemical analysis by Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS), Rockwell hardness testing, and tensile testing. The laboratory data indicated the bolts failed by intergranular stress corrosion cracking (IGSCC). There was no evidence that the bolts failed due to fatigue cracking or mechanical overload. (authors)

  10. Activation of threaded bolting elements | Dvořák | Journal of ...

    African Journals Online (AJOL)

    The article deals with the activation of bolting elements with a thread on them or equipped with threaded bushing through drilling and installation device. The article also enumerates the most frequently used bolting elements of this type and applied equipment with technical parameters in the coal mines of the ...

  11. A critical flaw size approach for predicting the strength of bolted glass connections

    DEFF Research Database (Denmark)

    Watson, James; Nielsen, Jens Henrik; Overend, Mauro

    2013-01-01

    The use of bolted connections in glass installations is common place in contemporary architecture. However, it is difficult to predict the load bearing capacity of these connections accurately due to the several factors that influence the strength of glass in the region of the bolt hole, namely: ...... connections that are useful for real-world applications. © 2013 Elsevier Ltd....

  12. Reflections on Friction in Quantum Mechanics

    Directory of Open Access Journals (Sweden)

    Yair Rezek

    2010-08-01

    Full Text Available Distinctly quantum friction effects of three types are surveyed: internalfriction, measurement-induced friction, and quantum-fluctuation-induced friction. We demonstrate that external driving will lead to quantum internal friction, and critique the measurement-based interpretation of friction. We conclude that in general systems will experience internal and external quantum friction over and beyond the classical frictional contributions.

  13. Non-destructive testing of full-length bonded rock bolts based on HHT signal analysis

    Science.gov (United States)

    Shi, Z. M.; Liu, L.; Peng, M.; Liu, C. C.; Tao, F. J.; Liu, C. S.

    2018-04-01

    Full-length bonded rock bolts are commonly used in mining, tunneling and slope engineering because of their simple design and resistance to corrosion. However, the length of a rock bolt and grouting quality do not often meet the required design standards in practice because of the concealment and complexity of bolt construction. Non-destructive testing is preferred when testing a rock bolt's quality because of the convenience, low cost and wide detection range. In this paper, a signal analysis method for the non-destructive sound wave testing of full-length bonded rock bolts is presented, which is based on the Hilbert-Huang transform (HHT). First, we introduce the HHT analysis method to calculate the bolt length and identify defect locations based on sound wave reflection test signals, which includes decomposing the test signal via empirical mode decomposition (EMD), selecting the intrinsic mode functions (IMF) using the Pearson Correlation Index (PCI) and calculating the instantaneous phase and frequency via the Hilbert transform (HT). Second, six model tests are conducted using different grouting defects and bolt protruding lengths to verify the effectiveness of the HHT analysis method. Lastly, the influence of the bolt protruding length on the test signal, identification of multiple reflections from defects, bolt end and protruding end, and mode mixing from EMD are discussed. The HHT analysis method can identify the bolt length and grouting defect locations from signals that contain noise at multiple reflected interfaces. The reflection from the long protruding end creates an irregular test signal with many frequency peaks on the spectrum. The reflections from defects barely change the original signal because they are low energy, which cannot be adequately resolved using existing methods. The HHT analysis method can identify reflections from the long protruding end of the bolt and multiple reflections from grouting defects based on mutations in the instantaneous

  14. Friction in volcanic environments

    Science.gov (United States)

    Kendrick, Jackie E.; Lavallée, Yan

    2016-04-01

    Volcanic landscapes are amongst the most dynamic on Earth and, as such, are particularly susceptible to failure and frictional processes. In rocks, damage accumulation is frequently accompanied by the release of seismic energy, which has been shown to accelerate in the approach to failure on both a field and laboratory scale. The point at which failure occurs is highly dependent upon strain-rate, which also dictates the slip-zone properties that pertain beyond failure, in scenarios such as sector collapse and pyroclastic flows as well as the ascent of viscous magma. High-velocity rotary shear (HVR) experiments have provided new opportunities to overcome the grand challenge of understanding faulting processes during volcanic phenomena. Work on granular ash material demonstrates that at ambient temperatures, ash gouge behaves according to Byerlee's rule at low slip velocities, but is slip-weakening, becoming increasingly lubricating as slip ensues. In absence of ash along a slip plane, rock-rock friction induces cataclasis and heating which, if sufficient, may induce melting (producing pseudotachylyte) and importantly, vesiculation. The viscosity of the melt, so generated, controls the subsequent lubrication or resistance to slip along the fault plane thanks to non-Newtonian suspension rheology. The shear-thinning behaviour and viscoelasticity of frictional melts yield a tendency for extremely unstable slip, and occurrence of frictional melt fragmentation. This velocity-dependence acts as an important feedback mechanism on the slip plane, in addition to the bulk composition, mineralogy and glass content of the magma, that all influence frictional behaviour. During sector collapse events and in pyroclastic density currents it is the frictional properties of the rocks and ash that, in-part, control the run-out distance and associated risk. In addition, friction plays an important role in the eruption of viscous magmas: In the conduit, the rheology of magma is integral

  15. Degradation and failure of bolting in nuclear power plants: Volume 1

    International Nuclear Information System (INIS)

    Nickell, R.E.

    1988-04-01

    These two volumes provide the documentation for industry resolution of the US Nuclear Regulatory Commission (NRC) generic issue B-29, Degradation and Failure of Bolting in Nuclear Power Plants. The issue was identified as a consequence of concerns about the structural integrity of component supports circa 1980. When bolting integrity became a separate issue in 1982, the utility industry responded by forming a Task Group on Bolting under the aegis of the Atomic Industrial Forum (AIF) and the Materials Properties Council (MPC). The AIF/MPC Task Group on Bolting formulated a comprehensive nineteen-task action plan aimed at resolution of the issue, with implementation of the plan, the responsibility of EPRI and the affected Owner's Groups. EPRI organized a matrix-managed Generic Bolted Joint Integrity Program to carry out the research, with the results reported herein

  16. Detection of cracks in stud bolts of nuclear reactor by novel ultrasonic technique

    International Nuclear Information System (INIS)

    Oh, W.D.; Lee, J.H.; Choi, S.W.; Park, M.H.

    2004-01-01

    The stud bolt is one of the most critical parts for the safety of reactor vessels in nuclear power plants. However, in the practical application of ultrasonic technique for crack detection in stud bolt, the classification of crack signal from the signals reflected from threads in stud bolt is very difficult. In this study, shadow effect technique combined with new signal processing method has been investigated to enhance the detectability of small crack initiated from root of thread in stud bolt. The key idea of new signal processing concept is based on the fact that the shape of waveforms from the threads is uniform since the shape of the threads in a bolt is same. If some cracks exist in the thread, the flaw signals are different from the reference signals. It has shown that the small flaws can be effectively detected by novel ultrasonic technique combined with this new signal processing concept. (orig.)

  17. The evaluation on clamping force of high strength bolts by length parameter

    International Nuclear Information System (INIS)

    Kim, Kang-Seok; Nah, Hwan-Seon; Lee, Hyeon-Ju; Lee, Kang-Min

    2009-01-01

    It has been reported that the length parameter of high strength bolts results in the variance in tension loads. The required turn for each length is specified in AISC RCSC specification. This study was focused on evaluating any influence on the clamping torque subjected to length parameter of high strength bolts. The two kinds of high strength bolts of specimen are as follows; High Strength Hexagon bolt defined on ASTM A490 and Torque Shear Bolt on KS B 2819. The length parameter ranged from 60mm(3d) to 140mm(7d). The torque, turn of nut and the clamping force were analyzed to review whether length parameter can be affected on the required tension load. To test whether the length parameter has an impact on the torque and turn of nut for the required strength and clamping force, statistical analysis is carried out. (author)

  18. Conceptual Design Study on Bolts for Self-Loosing Preventable Threaded Fasteners

    Science.gov (United States)

    Noma, Atsushi; He, Jianmei

    2017-11-01

    Threaded fasteners using bolts is widely applied in industrial field as well as various fields. However, threaded fasteners using bolts have loosing problems and cause many accidents. In this study, the purpose is to obtain self-loosing preventable threaded fasteners by applying spring characteristic effects on bolt structures. Helical-cutting applied bolt structures is introduced through three dimensional (3D) CAD modeling tools. Analytical approaches for evaluations on the spring characteristic effects helical-cutting applied bolt structures and self-loosing preventable performance of threaded fasteners were performed using finite element method and results are reported. Comparing slackness test results with analytical results and more details on evaluating mechanical properties will be executed in future study.

  19. Energy Neutral Wireless Bolt for Safety Critical Fastening

    Directory of Open Access Journals (Sweden)

    Biruk B. Seyoum

    2017-09-01

    Full Text Available Thermoelectric generators (TEGs are now capable of powering the abundant low power electronics from very small (just a few degrees Celsius temperature gradients. This factor along with the continuously lowering cost and size of TEGs, has contributed to the growing number of miniaturized battery-free sensor modules powered by TEGs. In this article, we present the design of an ambient-powered wireless bolt for high-end electro-mechanical systems. The bolt is equipped with a temperature sensor and a low power RF chip powered from a TEG. A DC-DC converter interfacing the TEG with the RF chip is used to step-up the low TEG voltage. The work includes the characterizations of different TEGs and DC-DC converters to determine the optimal design based on the amount of power that can be generated from a TEG under different loads and at temperature gradients typical of industrial environments. A prototype system was implemented and the power consumption of this system under different conditions was also measured. Results demonstrate that the power generated by the TEG at very low temperature gradients is sufficient to guarantee continuous wireless monitoring of the critical fasteners in critical systems such as avionics, motorsport and aerospace.

  20. Bolted flanged connections subjected to longitudinal bending moments

    International Nuclear Information System (INIS)

    Blach, A.E.

    1992-01-01

    Flanges in piping systems and also pressure vessel flanges on tall columns are often subjected to longitudinal bending moments of considerable magnitude, be it from thermal expansion stresses in piping systems or from wind or seismic loadings on tall vertical pressure vessels. Except for the ASME Code, Section III, Subsections NB, NC, and ND, other pressure vessel and piping codes do not contain design ASME Nuclear Power Plant Code (Section III), an empirical formula is given, expressing a longitudinal bending moment in bolted flanged connections in terms of an equivalent internal pressure to be added to the design pressure of the flange. In this paper, an attempt is made to analyse the stresses on flanges and bolting due to external bending moments and to compare flange thicknesses thus obtained with thicknesses required using the equivalent design pressure specified in Subsections NB, NC, and ND. A design method is proposed, based on analysis and experimental work, which may be suitable for flange bending moment analysis when the rules of the Nuclear Power Plant Code are not mandatory. (orig.)

  1. Energy Neutral Wireless Bolt for Safety Critical Fastening.

    Science.gov (United States)

    Seyoum, Biruk B; Rossi, Maurizio; Brunelli, Davide

    2017-09-26

    Thermoelectric generators (TEGs) are now capable of powering the abundant low power electronics from very small (just a few degrees Celsius) temperature gradients. This factor along with the continuously lowering cost and size of TEGs, has contributed to the growing number of miniaturized battery-free sensor modules powered by TEGs. In this article, we present the design of an ambient-powered wireless bolt for high-end electro-mechanical systems. The bolt is equipped with a temperature sensor and a low power RF chip powered from a TEG. A DC-DC converter interfacing the TEG with the RF chip is used to step-up the low TEG voltage. The work includes the characterizations of different TEGs and DC-DC converters to determine the optimal design based on the amount of power that can be generated from a TEG under different loads and at temperature gradients typical of industrial environments. A prototype system was implemented and the power consumption of this system under different conditions was also measured. Results demonstrate that the power generated by the TEG at very low temperature gradients is sufficient to guarantee continuous wireless monitoring of the critical fasteners in critical systems such as avionics, motorsport and aerospace.

  2. Thermo-mechanical finite element analysis of bolted cask lid structures

    International Nuclear Information System (INIS)

    Wieser, G.; Qiao, L.; Eberle, A.; Voelzke, H.

    2004-01-01

    Analysis of complex bolted cask lid structures under mechanical or thermal accident conditions is important for the evaluation of cask integrity and leak tightness in package design assessment according to the transport regulations or in aircraft crash scenarios. In this context BAM is developing methods based on finite elements (FE) to calculate the effects of mechanical impacts onto the bolted lid structures as well as effects caused by severe fire scenarios. In the case of fire it might not be enough to perform only a thermal heat transfer analysis. A complex cask design together with a severe hypothetical time-temperature curve representing an accident fire scenario will create a strong transient heating up of the cask body and its lid system. This causes relative displacements between the seals and their counterparts that can be analysed by a so-called thermomechanical calculation. Although it is currently not possible to directly correlate leakage rates with results from deformation analyses, an appropriate finite element model of the considered type of metallic lid seal has been developed. For the present it is possible to estimate the behaviour of the seal based on the calculated relative displacements at its seating and the behaviour of the lid bolts under the impact load or the temperature field, respectively. Except for the lid bolts, the geometry of the cask and the mechanical loading is axisymmetric which simplifies the analysis considerably, and a two-dimensional finite-element model with substitute lid bolts may be used. The substitute bolts are modelled as one-dimensional truss or beam elements. An advanced two-dimensional bolt submodel represents the bolts with plane stress continuum elements. This paper discusses the influence of different bolt modellings on the relative displacements at the seating of the seals. The influence of bolt modelling, thermal properties and the detailed geometry of the two-dimensional finite-element models on the

  3. Thermo-mechanical finite element analyses of bolted cask lid structures

    International Nuclear Information System (INIS)

    Wieser, G.; Qiao Linan; Eberle, A.; Voelzke, H.

    2004-01-01

    The analysis of complex bolted cask lid structures under mechanical or thermal accident conditions is important for the evaluation of cask integrity and leak-tightness in package design assessment according to the Transport Regulations or in aircraft crash scenarios. In this context BAM is developing methods based on Finite Elements to calculate the effects of mechanical impacts onto the bolted lid structures as well as effects caused by severe fire scenarios. I n case of fire it might be not enough to perform only a thermal heat transfer analysis. The complex cask design in connection with a severe hypothetical time-temperature-curve representing an accident fire scenario will create a strong transient heating up of the cask body and its lid system. This causes relative displacements between the seals and its counterparts that can be analyzed by a so-called thermo-mechanical calculation. Although it is currently not possible to correlate leakage rates with results from deformation analyses directly an appropriate Finite Element model of the considered type of metallic lid seal has been developed. For the present it is possible to estimate the behaviour of the seal based on the calculated relative displacements at its seating and the behaviour of the lid bolts under the impact load or the temperature field respectively. Except of the lid bolts the geometry of the cask and the mechanical loading is axial-symmetric which simplifies the analysis considerably and a two-dimensional Finite Element model with substitute lid bolts may be used. The substitute bolts are modelled as one-dimensional truss or beam elements. An advanced two-dimensional bolt submodel represents the bolts with plane stress continuum elements. This paper discusses the influence of different bolt modelling on the relative displacements at the seating of the seals. Besides this, the influence of bolt modelling, thermal properties and detail in geometry of the two-dimensional Finite Element models on

  4. Hand Grip Strength Vs. Sprint Effectiveness in Amputee Soccer Players.

    Science.gov (United States)

    Wieczorek, Marta; Wiliński, Wojciech; Struzik, Artur; Rokita, Andrzej

    2015-11-22

    Amputee soccer is one of the types of soccer designed for the disabled, especially those who have undergone amputations, as well as those with extremity dysfunction. The objective of the study was to find the relationship between hand grip strength and sprint time in amputee soccer players. Thirteen field amputee soccer players participated in the study. A SAEHAN hydraulic hand dynamometer manufactured by Jamar was used for hand grip strength measurements. The sprint running test was conducted over a distance of 30 m. The Fusion Smart Speed System was employed for running time measurements. No statistically significant relationships were found between hand grip strength of the left or right hand, and sprint times over 1, 5, 10, 15, 20, 25 and 30 m. Analysis of the running velocity curve of the subjects showed an interesting profile characterized by a 15 meter-long acceleration phase and a significant velocity increase over a distance of 20 - 25 m. The study suggests that there is no relationship between hand grip strength and sprint effectiveness in amputee soccer players. The specificity of locomotion with the use of elbow crutches among elite Polish amputee soccer players probably accounts for the profile of the sprint velocity curve. Extension of the acceleration phase in the sprint run and a velocity increase in the subsequent part of the run were observed.

  5. Hand Grip Strength Vs. Sprint Effectiveness in Amputee Soccer Players

    Directory of Open Access Journals (Sweden)

    Wieczorek Marta

    2015-12-01

    Full Text Available Amputee soccer is one of the types of soccer designed for the disabled, especially those who have undergone amputations, as well as those with extremity dysfunction. The objective of the study was to find the relationship between hand grip strength and sprint time in amputee soccer players. Thirteen field amputee soccer players participated in the study. A SAEHAN hydraulic hand dynamometer manufactured by Jamar was used for hand grip strength measurements. The sprint running test was conducted over a distance of 30 m. The Fusion Smart Speed System was employed for running time measurements. No statistically significant relationships were found between hand grip strength of the left or right hand, and sprint times over 1, 5, 10, 15, 20, 25 and 30 m. Analysis of the running velocity curve of the subjects showed an interesting profile characterized by a 15 meter-long acceleration phase and a significant velocity increase over a distance of 20 – 25 m. The study suggests that there is no relationship between hand grip strength and sprint effectiveness in amputee soccer players. The specificity of locomotion with the use of elbow crutches among elite Polish amputee soccer players probably accounts for the profile of the sprint velocity curve. Extension of the acceleration phase in the sprint run and a velocity increase in the subsequent part of the run were observed.

  6. Bone metabolism and hand grip strength response to aerobic versus ...

    African Journals Online (AJOL)

    Bone metabolism and hand grip strength response to aerobic versus resistance exercise training in non-insulin dependent diabetic patients. ... Objective: The aim of this study was to compare the changes in handgrip strength and bone metabolism after 6 months between aerobic and resistance exercise training in ...

  7. Grip and Pinch Strength Norms for Michigan Workers

    Directory of Open Access Journals (Sweden)

    Joel M. Phillips M.S., OTRL

    2013-06-01

    Full Text Available The purpose of this study was to create a norm reference of current grip and pinch strength norms for working-age Michigan adults. This normative study included a convenience sample of 179 volunteers who were employees at car plants in South East Michigan or hospital sites in West Michigan. Participants’ ages ranged from between 20 and 62 years of age with a mean age of 49.15 years. There were 78 females (44% and 101 males (56%. Subjects were classified by gender and in the age categories of ages 20 to 49 years and ages 50-62 years. Grip and pinch strength norms were collected following the American Society of Hand Therapy protocol. The norms from these working adults were calculated with descriptive statistics for males and females in two age classifications: ages 20 to 49 and ages 50 to 62 years. Standard Errors (SE are better than the 1985 norms for both males and females ages 20 to 49 years. SEs are higher than the ages 20 to 49 years’ norms for the ages 50 to 62 years age categories in both males and females. These norms offer a point of comparison for clinicians to use for clients in Michigan who are ages 20 to 62 years and who have a goal to improve their grip strength. Clients’ grip and pinch strength could be compared to their age level or gender norms using the comparison for one standard deviation above, below, or at the means.

  8. Study on the collision-mechanical properties of tomatoes gripped by ...

    African Journals Online (AJOL)

    The data of collision-mechanical property of tomatoes gripped by robot fingers are important for the gripping control of tomato harvesting robot. In the study, tests of controlling the fingers to grip tomatoes were conducted to ascertain the effects of input current, motor speed and impact positions on the impact force of fingers ...

  9. Study on the collision-mechanical properties of tomatoes gripped by ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-12-15

    Dec 15, 2009 ... The data of collision-mechanical property of tomatoes gripped by robot fingers are important for the gripping control of tomato harvesting robot. In the study, tests of controlling the fingers to grip tomatoes were conducted to ascertain the effects of input current, motor speed and impact positions on the impact ...

  10. The role of friction in the mechanism of retaining the partial removable dentures with double crown system.

    Science.gov (United States)

    Dąbrowa, Tomasz; Dobrowolska, Anna; Wieleba, Wojciech

    2013-01-01

    Cylindrical telescopic crowns belong to bolt dentures, because their adhesion strength is based on the friction force. The magnitude of static and slide friction forces depends on the strain within the contact area and properties of materials employed. Friction force value between telescope elements declines in the first phase of wearing period and, subsequently, maintains particular constant value of 8 to 10 N. In the telescopic technique, homo and heterogenic joints are used. The following prosthodontic materials have been examined: goldbase alloys (Degudent Kiss, Degulor M), cobalt-base alloy (Brealloy 270), ceramics (Zircon Oxide, Zirconia) during tribological investigations on FGP composite resin. The cooperating surfaces were moistened with synthetic saliva. The research confirmed the dependence of the static friction coefficient on the contact pressure for the analyzed pairs of materials used in prosthodontics. The biggest effect of the contact pressure on the coefficient of friction value occurs when the ceramic rubs on FGP composite resin. The most stable friction coefficient in the context of contact pressure changes as well as life has been found in the case of the cobalt alloy Brealloy 270. An interesting material is a gold alloy Degulor M, for which the coefficient of friction varies only slightly with pressure in the range of 0.6 to 0.9 MPa.

  11. Internal friction in zirconium

    International Nuclear Information System (INIS)

    Miyada-Naborikawa, L.T.; De Batist, R.; Eersels, L.

    1981-01-01

    The effect of type (bending, tension or torsion) and temperature (100 K, 300 K) of deformation on the internal friction spectrum of well-annealed polycrystalline zirconium has been investigated at frequencies of about 1 Hz and about 100 Hz. The result of ageing at temperatures not higher than 300 K on both the modulus and the internal friction is also described. The observed peaks are discussed in terms of either dislocation relaxation or dislocation point defect interaction effects and combined with literature data to obtain better defined values for the relaxation parameters

  12. Friction Rock Stabilizers: how and why they work

    International Nuclear Information System (INIS)

    Anon.

    1978-01-01

    This paper discusses the device itself, the mechanism by which it functions and compares this mechanism with more common devices such as the mechanical roof bolt and the resin rebar system. A Friction Rock Stabilizer can be pictured as a split pipe, set into the geologic mass to be reinforced; thus, the trade name ''Split Set.'' The configuration is shown. Friction Rock Stabilizers are 1-1/2'' outside diameter as manufactured and normally are put into 1-3/8'' diameter boreholes in rock. Depending on the smoothness, diameter throughout its length, straightness of the hole and frictional coefficient, and anchorage of 4/4 to 1-1/2 tons is obtained per foot of borehole contact upon installation. The device can be easily installed with any common air percussion impact drill. The steel used in the fixture is a high formability steel with approximately a 70,000 psi yield. Wall thickness is near 0.090 inch. The stabilizer is tapered on the upper end for insertion into the borehole and on the other end a ring is welded to the unit as a retainer for the roof plate. Upon installation it provides a yieldable support and, with time, becomes more rigidly anchored in the rock to provide the restraint necessary for long term stability. It is a full contact system which preloads the rock in compression to increase stability. The yieldable aspects of Friction Rock Stabilizers without loss of restraint against the rock cannot be overemphasized. Also, the preload of the rock by the device during and after installation is very important. The preload acts in a plane perpendicular to the axis of the device and also along the axis as it is driven in. This combined effect produces a zone of triaxial compression around the device and, when coupled with the pressure bulb which is present in the rock form the plate, we end up with a unique pear-shaped compression zone around each device

  13. Frictional coefficient depending on active friction radius with BPV ...

    African Journals Online (AJOL)

    The comparison of estimated frictional coefficient from numerical output is in agreement with vis-à-vis corresponding similar computed from the virtual braking system model in the Simulink. The results indicated that highest frictional coefficient of 0.7 was obtained on the piston side of the rotor disc and active friction radius is ...

  14. The Influence on Modal Parameters of Thin Cylindrical Shell under Bolt Looseness Boundary

    Directory of Open Access Journals (Sweden)

    Hui Li

    2016-01-01

    Full Text Available The influence on modal parameters of thin cylindrical shell (TCS under bolt looseness boundary is investigated. Firstly, bolt looseness boundary of the shell is divided into two types, that is, different bolt looseness numbers and different bolt looseness levels, and natural frequencies and mode shapes are calculated by finite element method to roughly master vibration characteristics of TCS under these conditions. Then, the following measurements and identification techniques are used to get precise frequency, damping, and shape results; for example, noncontact laser Doppler vibrometer and vibration shaker with excitation level being precisely controlled are used in the test system; “preexperiment” is adopted to determine the required tightening torque and verify fixed constraint boundary; the small-segment FFT processing technique is employed to accurately measure nature frequency and laser rotating scanning technique is used to get shape results with high efficiency. Finally, based on the measured results obtained by the above techniques, the influence on modal parameters of TCS under two types of bolt looseness boundaries is analyzed and discussed. It can be found that bolt looseness boundary can significantly affect frequency and damping results which might be caused by changes of nonlinear stiffness and damping and in bolt looseness positions.

  15. A load measuring anchor plate for rock bolt using fiber optic sensor

    Science.gov (United States)

    Ho, Siu Chun Michael; Li, Weijie; Wang, Bo; Song, Gangbing

    2017-05-01

    Rock bolts are the devices that used to reinforce the rock masses in mining tunnels and underground excavation structures. The loading level of the rock bolt indicates the reinforcing efficiency and is able to ensure safe underground operation by giving warnings to the underground miners prior to any accidents. Therefore, it is very important to monitor the load level of the rock bolts. In this short communication, we propose a smart anchor plate, a simple but effective device that uses fiber Bragg gratings (FBG) type optic sensor, to monitor the load level of the rock bolt. Instead of measuring the stress/strain on the rock bolt, which adds more complexity, the proposed method monitors the rock bolt load by measuring the load experience on the rock bolt anchor plate. Such a configuration has the advantages of simple structure and flexible implementation. In experimental observation, the FBG instrumented anchor plate is able to observe the load of the plate with good repeatability. This test will lead to further in-depth studies involving finite element analysis as well as more complex applications.

  16. A Study on the Fracture Control of Rock Bolts in High Ground Pressure Roadways of Deep Mines

    Directory of Open Access Journals (Sweden)

    Wen Jinglin

    2015-01-01

    Full Text Available According to the frequent fractures of rock bolts in high ground pressure roadways of deep mines, this paper analyzes the mechanism of fractures and concludes that high ground pressure and material de-fects are main reasons for the fracture of rock bolts. The basic idea of fracture control of rock bolts in high ground pressure roadways of deep mines is to increase the yield load and the limit load of rock bolt materials and reduce the actual load of rock bolts. There are four ways of controlling rock bolt fracture: increasing the rock bolt diameter, strengthening bolt materials, weakening support rigidity and the implementation of double supporting. With the roadway support of the 2302 working face of a coal mine as the project background, this paper carries out a study on the effect of two schemes, increasing the rock bolt diameter and the double supporting technique through methods of theoretical analysis, numerical simulation and so on. It determines the most reasonable diam-eter of rock bolts and the best delay distance of secondary support. Practices indicate that rock bolt fracture can be effectively controlled through the double supporting technique, which strengthens the roof and two sides through the first supporting technique and strengthens side angles through the secondary supporting technique.

  17. Analysis on shearing deformation of roof support bolt in gob-side entry of fully-mechanized caving face

    Energy Technology Data Exchange (ETDEWEB)

    Miao Xie-xing; Mao Xian-biao; Zhu Chuan-qu; Liu Wei-qun [China University of Mining and Technology, Xuzhou (China)

    2005-07-01

    The bolt probably supports larger shearing deformation in the course of huge deformation of roadway surrounding rock, for instance the cable bolts-metal mesh reinforcement of small pillar adopted largely in coalmines, especially that in gob-side entry of fully-mechanized caving face (FCF). The mechanism that the full-column roof support bolt sustains during shearing deformation in gob-side entry of FCF was analyzed by theoretical research, and the shearing stress distribution, the maximum shearing force and the maximum shearing stress in bolts were obtained with the help of numerical simulation. It is indicated that the maximum shearing stress of the roof support bolt in gob-side entry of FCF will approach or exceed the allowable shearing stress of bolt materials in condition of large deformation in surrounding rock, and here, the shearing effect of bolt is not to be neglected. 6 refs., 4 figs., 1 tab.

  18. The relation between force and movement when grasping an object with a precision grip.

    Science.gov (United States)

    Biegstraaten, Marianne; Smeets, Jeroen B J; Brenner, Eli

    2006-05-01

    When reaching out for objects, the digits' paths curve so that they approach their positions of contact moving more or less perpendicularly to the local surface orientation. This increases the accuracy of positioning the digits and ensures that any forces exerted at contact are nearly perpendicular to the surface, so that friction will prevent the digits from slipping along the surface. When lifting the object a similar force perpendicular to the surface is needed to prevent the object from slipping from one's fingers. In order to determine whether these two issues are dealt with simultaneously we let subjects pick up a cube from three different starting positions and measured the digits' movements and forces from before contact until the moment the cube started moving. The impact force was low. After impact, the digits spent about 200 ms in contact with the surface of the cube before the latter started to move. The digits first decelerated, and then they gradually built up the grip- and lift forces to move the cube upwards. We found no direct relationship between the control of the reaching movement towards the object and the force applied at the surface of the object to pick it up. We conclude that the reaching and lifting movements are quite independent.

  19. Integrity of Bolted Angle Connections Subjected to Simulated Column Removal

    Science.gov (United States)

    Weigand, Jonathan M.; Berman, Jeffrey W.

    2016-01-01

    Large-scale tests of steel gravity framing systems (SGFSs) have shown that the connections are critical to the system integrity, when a column suffers damage that compromises its ability to carry gravity loads. When supporting columns were removed, the SGFSs redistributed gravity loads through the development of an alternate load path in a sustained tensile configuration resulting from large vertical deflections. The ability of the system to sustain such an alternate load path depends on the capacity of the gravity connections to remain intact after undergoing large rotation and axial extension demands, for which they were not designed. This study experimentally evaluates the performance of steel bolted angle connections subjected to loading consistent with an interior column removal. The characteristic connection behaviors are described and the performance of multiple connection configurations are compared in terms of their peak resistances and deformation capacities. PMID:27110059

  20. Robustness of steel joints with stainless steel bolts in fire

    Science.gov (United States)

    Satheeskumar, N.; Davison, J. B.

    2014-12-01

    The robustness of steel joints in fire is important for steel building structures because of the need to prevent progressive collapse. Stainless steel is widely used in building construction mainly because of its corrosion resistance, but it also possesses improved fire resistance compared with conventional non-alloy, fine grain structural steels. Extensive research performed on the robustness of steel joints in fire has revealed that failure at elevated temperature may be controlled by bolt shear for fin plate and web cleat connections. Hence, this study focussed on the use of stainless steel in experimental tests conducted on fin plate and web cleat connections at high temperatures. In addition, this study investigated the use of a component-based model to predict connection performance at elevated temperature.

  1. Experimental determination of satellite bolted joints thermal resistance

    Science.gov (United States)

    Mantelli, Marcia Barbosa Henriques; Basto, Jose Edson

    1990-01-01

    The thermal resistance was experimentally determined of the bolted joints of the first Brazilian satellite (SCD 01). These joints, used to connect the satellite structural panels, are reproduced in an experimental apparatus, keeping, as much as possible, the actual dimensions and materials. A controlled amount of heat is forced to pass through the joint and the difference of temperature between the panels is measured. The tests are conducted in a vacuum chamber with liquid nitrogen cooled walls, that simulates the space environment. Experimental procedures are used to avoid much heat losses, which are carefully calculated. Important observations about the behavior of the joint thermal resistance with the variation of the mean temperature are made.

  2. Visual Inspection of the Flow Distribution Plate Bolts of a Nuclear Steam Generator

    International Nuclear Information System (INIS)

    Jeong, Woo Tae; Kim, Suk Tae; Sohn, Wook; Kang, Duk Won; Kang, Seok Chul

    2007-01-01

    To develop a system for visually inspecting the flow distribution plate (FDP) bolts of a nuclear steam generator, we reviewed several types of similar inspection equipment. The equipment which are currently available are mostly for inspecting lower part of a steam generator such as tube sheets and annulus except ELVS (Eggcrate Visual Inspection System). However, the design concept of ELVS could not be used for developing a device which enables the visual inspection of flow distribution plate bolts. Therefore, based on the current state of the art technology on the similar equipment, we conceptually designed a new inspection system for checking the FDP bolts

  3. Bolt-Grout Interactions in Elastoplastic Rock Mass Using Coupled FEM-FDM Techniques

    Directory of Open Access Journals (Sweden)

    Debasis Deb

    2010-01-01

    Full Text Available Numerical procedure based on finite element method (FEM and finite difference method (FDM for the analysis of bolt-grout interactions are introduced in this paper. The finite element procedure incorporates elasto-plastic concepts with Hoek and Brown yield criterion and has been applied for rock mass. Bolt-grout interactions are evaluated based on finite difference method and are embedded in the elasto-plastic procedures of FEM. The experimental validation of the proposed FEM-FDM procedures and numerical examples of a bolted tunnel are provided to demonstrate the efficacy of the proposed method for practical applications.

  4. Optimized bolt tightening strategies for gasketed flanged pipe joints of different sizes

    International Nuclear Information System (INIS)

    Abid, Muhammad; Khan, Ayesha; Nash, David Hugh; Hussain, Masroor; Wajid, Hafiz Abdul

    2016-01-01

    Achieving a proper preload in the bolts of a gasketed bolted flanged pipe joint during joint assembly is considered important for its optimized performance. This paper presents results of detailed non-linear finite element analysis of an optimized bolt tightening strategy of different joint sizes for achieving proper preload close to the target stress values. Industrial guidelines are considered for applying recommended target stress values with TCM (torque control method) and SCM (stretch control method) using a customized optimization algorithm. Different joint components performance is observed and discussed in detail.

  5. Student figures in friction

    DEFF Research Database (Denmark)

    Nielsen, Gritt B.

    , students' room for participation in their own learning, influenced by demands for efficiency, flexibility and student-centred education. The thesis recasts the anthropological endeavour as one of ‘figuration work'. That is, ‘frictional events' are explored as moments when conflicting figures...

  6. Skin tribology: Science friction?

    NARCIS (Netherlands)

    Heide, E. van der; Zeng, X.; Masen, M.A.

    2013-01-01

    The application of tribological knowledge is not just restricted to optimizing mechanical and chemical engineering problems. In fact, effective solutions to friction and wear related questions can be found in our everyday life. An important part is related to skin tribology, as the human skin is

  7. Intelligent Flow Friction Estimation

    Directory of Open Access Journals (Sweden)

    Dejan Brkić

    2016-01-01

    Full Text Available Nowadays, the Colebrook equation is used as a mostly accepted relation for the calculation of fluid flow friction factor. However, the Colebrook equation is implicit with respect to the friction factor (λ. In the present study, a noniterative approach using Artificial Neural Network (ANN was developed to calculate the friction factor. To configure the ANN model, the input parameters of the Reynolds Number (Re and the relative roughness of pipe (ε/D were transformed to logarithmic scales. The 90,000 sets of data were fed to the ANN model involving three layers: input, hidden, and output layers with, 2, 50, and 1 neurons, respectively. This configuration was capable of predicting the values of friction factor in the Colebrook equation for any given values of the Reynolds number (Re and the relative roughness (ε/D ranging between 5000 and 108 and between 10−7 and 0.1, respectively. The proposed ANN demonstrates the relative error up to 0.07% which had the high accuracy compared with the vast majority of the precise explicit approximations of the Colebrook equation.

  8. Internal rotor friction instability

    Science.gov (United States)

    Walton, J.; Artiles, A.; Lund, J.; Dill, J.; Zorzi, E.

    1990-01-01

    The analytical developments and experimental investigations performed in assessing the effect of internal friction on rotor systems dynamic performance are documented. Analytical component models for axial splines, Curvic splines, and interference fit joints commonly found in modern high speed turbomachinery were developed. Rotor systems operating above a bending critical speed were shown to exhibit unstable subsynchronous vibrations at the first natural frequency. The effect of speed, bearing stiffness, joint stiffness, external damping, torque, and coefficient of friction, was evaluated. Testing included material coefficient of friction evaluations, component joint quantity and form of damping determinations, and rotordynamic stability assessments. Under conditions similar to those in the SSME turbopumps, material interfaces experienced a coefficient of friction of approx. 0.2 for lubricated and 0.8 for unlubricated conditions. The damping observed in the component joints displayed nearly linear behavior with increasing amplitude. Thus, the measured damping, as a function of amplitude, is not represented by either linear or Coulomb friction damper models. Rotordynamic testing of an axial spline joint under 5000 in.-lb of static torque, demonstrated the presence of an extremely severe instability when the rotor was operated above its first flexible natural frequency. The presence of this instability was predicted by nonlinear rotordynamic time-transient analysis using the nonlinear component model developed under this program. Corresponding rotordynamic testing of a shaft with an interference fit joint demonstrated the presence of subsynchronous vibrations at the first natural frequency. While subsynchronous vibrations were observed, they were bounded and significantly lower in amplitude than the synchronous vibrations.

  9. PEBBLES Simulation of Static Friction and New Static Friction Benchmark

    International Nuclear Information System (INIS)

    Cogliati, Joshua J.; Ougouag, Abderrafi M.

    2010-01-01

    Pebble bed reactors contain large numbers of spherical fuel elements arranged randomly. Determining the motion and location of these fuel elements is required for calculating certain parameters of pebble bed reactor operation. This paper documents the PEBBLES static friction model. This model uses a three dimensional differential static friction approximation extended from the two dimensional Cundall and Strack model. The derivation of determining the rotational transformation of pebble to pebble static friction force is provided. A new implementation for a differential rotation method for pebble to container static friction force has been created. Previous published methods are insufficient for pebble bed reactor geometries. A new analytical static friction benchmark is documented that can be used to verify key static friction simulation parameters. This benchmark is based on determining the exact pebble to pebble and pebble to container static friction coefficients required to maintain a stable five sphere pyramid.

  10. Reliability of the Bulb Dynamometer for Assessing Grip Strength

    Directory of Open Access Journals (Sweden)

    Colleen Maher

    2018-04-01

    Full Text Available Background: Hand function is an overall indicator of health and is often measured using grip strength. Handheld dynamometry is the most common method of measuring grip strength. The purpose of this study was to determine the inter-rater and test-retest reliability, the reliability of one trial versus three trials, and the preliminary norms for a young adult population using the Baseline® Pneumatic Squeeze Bulb Dynamometer (30 psi. Methods: This study used a one-group methodological design. One hundred and three healthy adults (30 males and 73 females were recruited. Six measurements were collected for each hand per participant. The data was analyzed using Intraclass Correlation Coefficients (ICC two-way effects model (2,2 and paired-samples t-tests. Results: The ICC for inter-rater reliability ranged from 0.955 to 0.977. Conclusion: The results of this study suggest that the bulb dynamometer is a reliable tool to measure grip strength and should be further explored for reliable and valid use in diverse populations and as an alternative to the Jamar dynamometer.

  11. Spatio-Temporal Human Grip Force Analysis via Sensor Arrays

    Directory of Open Access Journals (Sweden)

    Florian P. Kolb

    2009-08-01

    Full Text Available This study describes a technique for measuring human grip forces exerted on a cylindrical object via a sensor array. Standardised resistor-based pressure sensor arrays for industrial and medical applications have been available for some time. We used a special 20 mm diameter grip rod that subjects could either move actively with their fingers in the horizontal direction or exert reactive forces against opposing forces generated in the rod by a linear motor. The sensor array film was attached to the rod by adhesive tape and covered approximately 45 cm2 of the rod surface. The sensor density was 4/cm2 with each sensor having a force resolution of 0.1 N. A scan across all sensors resulted in a corresponding frame containing force values at a frame repetition rate of 150/s. The force value of a given sensor was interpreted as a pixel value resulting in a false-colour image. Based on remote sensed image analysis an algorithm was developed to distinguish significant force-representing pixels from those affected by noise. This allowed tracking of the position of identified fingers in subsequent frames such that spatio-temporal grip force profiles for individual fingers could be derived. Moreover, the algorithm allowed simultaneous measurement of forces exerted without any constraints on the number of fingers or on the position of the fingers. The system is thus well suited for basic and clinical research in human physiology as well as for studies in psychophysics.

  12. Complication assessment and prevention strategies using midfoot fusion bolt for medial column stabilization in Charcot's osteoarthropathy

    DEFF Research Database (Denmark)

    Mehlhorn, Alexander T; Walther, Markus; Iblher, Niklas

    2016-01-01

    . There was a significant association between preoperative increased Hba1c value, presence of preoperative ulcer and wound infection. Healing of arthrodesis was demonstrated in 57% and a permanent weight-bearing foot without recurrent ulcer was achieved in 79%. The early and late postoperative complications could....... Since bolt dislocation takes place frequently, it was aimed to predict an appropriate time point for bolt removal under the condition that osseous healing has occurred. Fourteen consecutive patients with neuroosteoarthropathy of the foot and arch collapse were treated with open reduction...... and stabilization using midfoot fusion bolt and lateral lag screws. Age, gender, presence of preoperative osteomyelitis or ulcer, number of complications and operative revisions, Hba1c value, consolidation of arthrodesis, presence of a load-bearing foot and period to bolt dislocation was assessed. The mean follow...

  13. Preliminary aseismic analysis on bolts of driving mechanism in absorption sphere shutdown system

    International Nuclear Information System (INIS)

    Chen Feng; Li Tianjin; Zhang Zhengming; Huang Zhiyong; Bo Hanliang

    2012-01-01

    The absorption sphere shutdown system performs an important role in reactivity regulating and control. Driving mechanism is a set of key mechanical moving parts which is used to control falling of absorption spheres in absorption sphere shutdown system. It is about 5 m for driving mechanism with the slim structure, which is connected with the upper supported plate of metal reactor internals through storage vessel with bolts. Both the storage vessel and driving mechanism are equipment of seismic classification I. It is significant to calculate and check the bolts strength of driving mechanism. In this paper, complicate structure of driving mechanism was simplified to three variable cross sections and statically indeterminate problem was solved. The bolts at the bottom and on the top of the storage vessel were calculated and checked. The preliminary results indicate that the bolts strength is reliable and safe, and the supporting force at the most weak point of driving mechanism is as well obtained. (authors)

  14. A physical match of a metallic chip found on a bolt cutters' blade.

    Science.gov (United States)

    Finkelstein, Nir; Volkov, Nikolai; Novoselsky, Yehuda; Tsach, Tsadok

    2015-05-01

    Bolt cutters are known as devices which are used for cutting hard objects and rigid materials such as padlocks and bars. They are commonly used in instances of forced entries. In this case study, a bolt cutter was found in the car of two suspects in a grocery burglary. This study indicates how the presence of a small metallic chip found on a suspected bolt cutter can prove that the tool was used in the crime scene. During the initial examination, a metallic chip from the cut shackle padlock was found stuck to one of the bolt cutters' blades. By comparing the metallic chip's microscopic edge and the breaking (fracture) line of the padlock's shackle, a full physical match was noticed. We wish to report here how residue, even the smallest, can be used to link burglary tools to a crime scene with a high level of certainty. © 2015 American Academy of Forensic Sciences.

  15. A new polymorphism on chromosome 6 associated with bolting tendency in sugar beet.

    Science.gov (United States)

    Broccanello, Chiara; Stevanato, Piergiorgio; Biscarini, Filippo; Cantu, Dario; Saccomani, Massimo

    2015-12-07

    Premature flowering or bolting is an undesirable characteristic that causes severe sugar yield losses and interferes with harvesting. Vernalization is a prerequisite for the floral induction, achieved by exposure to low temperatures for 10-14 weeks. This process is also controlled by other environmental factors, such as long daylight photoperiods and a combination of genetic factors. The objective of this study was the identification of new genetic polymorphisms linked to bolting tendency in sugar beet. Two pollinators characterized by low and high bolting tendency were subjected to RAD-sequencing in order to detect discriminating SNPs between lines. 6,324 putative SNPs were identified. Of these, 192 were genotyped in a set of 19 pollinators, each comprising bolted and non-bolted individuals, for a total of 987 samples. Among the 192 candidate SNPs, the strongest overall association was found for SNP183 on chromosome 6 (p-value = 1.246 10(-13)). The association between SNP183 and bolting tendency was then confirmed in an independent population of 730 plants from 11 breeding lines (p-value = 0.0061). SNP183 is located in the intron of Bv_22330_orky, a sugar beet homolog of a matrix metalloproteinase (MMP) gene that could be implied in flowering in Arabidopsis thaliana. Our data support a significant association between an intronic SNP in the MMP gene located on chromosome 6 and the regulation of bolting tendency in sugar beet. The newly identified locus supports the polygenic nature of flowering control. The associated marker can be used to design SNP panels for the discrimination of bolters and non-bolters, to be used in sugar beet breeding programs for the development of improved germplasm with low bolting tendency.

  16. Analysis of anchor bolt belongs to fan in nuclear power plant

    International Nuclear Information System (INIS)

    Miao Xueliang; Luan Xingfeng; Zhang Wei; Bian Chunhua; Yu Xiaoyan; Xu Ke; Liu Hongqun

    2014-01-01

    Through on the fan anchor bolt material components, metallurgical structure and fracture analysis indicates that: material composition and microscopic are abnormal, it led to material brittle increased, the fracture is rock-candy structure, the last part is toughness structure. The reason is the the fan vibrate oversize. At last, we put forward some measures. Just like, control the vibration of the fan, set a nominal tightening torque when installing bolt. (authors)

  17. Efficiency of roof bolting in vertical mine shafts depending on rock deformation

    Energy Technology Data Exchange (ETDEWEB)

    Kozel, A.M. (VNIMI (USSR))

    1989-11-01

    Evaluates interaction of roof bolts used in mine shafts and the surrounding strata. Effects of stratification, mechanical rock properties, state of initial tension, developing fissures and cracks are comparatively evaluated. Time effects on state of stress of the strata surrounding a mine shaft are analyzed. Stress relaxation and its effects on interaction of roof bolts and the rock strata are investigated. Formulae that describe this interaction are derived. 7 refs.

  18. Estimation of clamping force in high-tension bolts through ultrasonic velocity measurement.

    Science.gov (United States)

    Jhang, Kyung-Young; Quan, Hai-Hua; Ha, Job; Kim, Noh-Yu

    2006-12-22

    The estimation of clamping force has been regarded as the main issue in the maintenance of high-tension bolts. This paper proposes a method which uses the dependency of ultrasonic velocity on stress based on the nonlinear elastic effect. The variation of ultrasonic velocity in the range of actual stress acting in the bolt is very small so that the precise measurement of ultrasonic velocity is needed. In this paper, we adopt a method to measure ultrasonic velocity, where the TOF (time of flight) of a tone-burst ultrasonic wave is precisely measured by using the phase detection technique. In order to verify the usefulness of the proposed method, two kinds of experiments are carried out. The first one measures ultrasonic velocity when the bolt is stressed by the tension tester, and from this, the exact axial force acting in the bolt can be determined. The results show good agreement with the expected linear relationship between ultrasonic velocity and axial stress. The second experiment measures ultrasonic velocity when the bolt is stressed by the torque wrench. The results show that ultrasonic velocity decreased as the torque increased, which is identical to the theoretically expected tendency. From these results, it can be said that the proposed method is adequate in evaluating clamping force in high-tension bolts.

  19. Experimental studies on the effects of bolt parameters on the bearing characteristics of reinforced rock.

    Science.gov (United States)

    Cheng, Liang; Zhang, Yidong; Ji, Ming; Zhang, Kai; Zhang, Minglei

    2016-01-01

    Roadways supported by bolts contain support structures that are built into the rock surrounding the roadway, referred to as reinforced rocks in this paper. Using physical model simulation, the paper investigates the bearing characteristics of the reinforced rock under different bolt parameters with incrementally increased load. The experimental results show that the stress at the measurement point inside the structure varies with the kinetic pressure. The stress increases slowly as the load is initially applied, displays accelerated growth in the middle of the loading application, and decreases or remains constant in the later stage of the loading application. The change in displacement of the surrounding rock exhibits the following characteristics: a slow increase when the load is first applied, accelerated growth in the middle stage, and violent growth in the later stage. There is a good correlation between the change in the measured stress and the change in the surrounding rock displacement. Increasing the density of the bolt support and the length and diameter of the bolt improves the load-bearing performance of the reinforced rock, including its strength, internal peak stress, and residual stress. Bolting improves the internal structure of the surrounding rocks, and the deterioration of the surrounding rock decreases with the distance between the bolt supports.

  20. Study on Mechanical Characteristics of Fully Grouted Rock Bolts for Underground Caverns under Seismic Loads

    Directory of Open Access Journals (Sweden)

    Guoqing Liu

    2017-01-01

    Full Text Available This study establishes an analytical model for the interaction between the bolt and surrounding rock based on the bearing mechanism of fully grouted rock bolts. The corresponding controlled differential equation for load transfer is deduced. The stress distributions of the anchorage body are obtained by solving the equations. A dynamic algorithm for the bolt considering shear damage on the anchoring interface is proposed based on the dynamic finite element method. The rationality of the algorithm is verified by a pull-out test and excavation simulation of a rounded tunnel. Then, a case study on the mechanical characteristics of the bolts in underground caverns under seismic loads is conducted. The results indicate that the seismic load may lead to stress originating from the bolts and damage on the anchoring interface. The key positions of the antiseismic support can be determined using the numerical simulation. The calculated results can serve as a reference for the antiseismic optimal design of bolts in underground caverns.

  1. Application of Fiber Bragg Grating Sensing Technology for Bolt Force Status Monitoring in Roadways

    Directory of Open Access Journals (Sweden)

    Minfu Liang

    2018-01-01

    Full Text Available Bolts support have become a major active support method in coal mine roadways to control roadway roof failure and improve surrounding rock structure stability. The traditional bolt force status monitoring (BFSM method has poor anti-interference performance, is easily affected by harsh downhole environments, and cannot support remote real-time monitoring. This paper presents a fiber Bragg grating (FBG bolt force sensor that monitors the force of roadway bolts. This sensor uses a cantilever and a diaphragm as elastic elements and two FBGs bonded on the top and bottom surfaces of the cantilever as sensing elements. The experimental results indicate that the measuring sensitivity is improved by using the center wavelength difference between the two FBGs. The sensitivity is 38.79 pm/kN within the range from 0 to 150 kN, and the correlation coefficient reaches 99.98%. The engineering applications show that the FBG sensing technology can automatically acquire, and monitoring results are of great significance in roadway anchorage engineering safety and bolt support quality evaluation. Furthermore, such a sensor is also widely used in quasi-distributed measurement and long-term online monitoring of bolt force status in such fields as geotechnical engineering, tunnel engineering, and slope engineering.

  2. An approach for the design of closure bolts of spent fuel elements transportation packages

    International Nuclear Information System (INIS)

    Mattar Neto, Miguel; Miranda, Carlos A.J.; Fainer, Gerson

    2009-01-01

    The spent fuel elements transportation packages must be designed for severe conditions including significant fire and impact loads corresponding to hypothetical accident conditions. In general, these packages have large flat lids connected to cylindrical bodies by closure bolts that can be the weak link in the containment system. The bolted closure design depends on the geometrical characteristics of the flat lid and the cylindrical body, including their flanges, on the type of the gaskets and their dimensions, and on the number, strength, and tightness of the bolts. There are well established procedures for the closure bolts design used in pressure vessels and piping. They can not be used directly in the bolts design applied to transportation packages. Prior to the use of these procedures, it is necessary consider the differences in the main loads (pressure for the pressure vessels and piping and impact loads for the transportation packages) and in the geometry (large flat lids are not used in pressure vessels and piping). So, this paper presents an approach for the design of the closure bolts of spent fuel elements transportation packages considering the impact loads and the typical geometrical configuration of the transportation packages. (author)

  3. Quantum tunneling with friction

    Science.gov (United States)

    Tokieda, M.; Hagino, K.

    2017-05-01

    Using the phenomenological quantum friction models introduced by P. Caldirola [Nuovo Cimento 18, 393 (1941), 10.1007/BF02960144] and E. Kanai [Prog. Theor. Phys. 3, 440 (1948), 10.1143/ptp/3.4.440], M. D. Kostin [J. Chem. Phys. 57, 3589 (1972), 10.1063/1.1678812], and K. Albrecht [Phys. Lett. B 56, 127 (1975), 10.1016/0370-2693(75)90283-X], we study quantum tunneling of a one-dimensional potential in the presence of energy dissipation. To this end, we calculate the tunneling probability using a time-dependent wave-packet method. The friction reduces the tunneling probability. We show that the three models provide similar penetrabilities to each other, among which the Caldirola-Kanai model requires the least numerical effort. We also discuss the effect of energy dissipation on quantum tunneling in terms of barrier distributions.

  4. High Speed Ice Friction

    Science.gov (United States)

    Seymour-Pierce, Alexandra; Sammonds, Peter; Lishman, Ben

    2014-05-01

    Many different tribological experiments have been run to determine the frictional behaviour of ice at high speeds, ostensibly with the intention of applying results to everyday fields such as winter tyres and sports. However, experiments have only been conducted up to linear speeds of several metres a second, with few additional subject specific studies reaching speeds comparable to these applications. Experiments were conducted in the cold rooms of the Rock and Ice Physics Laboratory, UCL, on a custom built rotational tribometer based on previous literature designs. Preliminary results from experiments run at 2m/s for ice temperatures of 271 and 263K indicate that colder ice has a higher coefficient of friction, in accordance with the literature. These results will be presented, along with data from further experiments conducted at temperatures between 259-273K (in order to cover a wide range of the temperature dependent behaviour of ice) and speeds of 2-15m/s to produce a temperature-velocity-friction map for ice. The effect of temperature, speed and slider geometry on the deformation of ice will also be investigated. These speeds are approaching those exhibited by sports such as the luge (where athletes slide downhill on an icy track), placing the tribological work in context.

  5. FRICTION BUFFER STOP DESIGN

    Directory of Open Access Journals (Sweden)

    Petr Guziur

    2017-08-01

    Full Text Available Friction buffer stops are the favoured construction of buffer stop, mainly due to its high resistance and variety of layout. Last but not least is its manner of deceleration induced upon impact and during the braking what makes it smart solution in railway transport safety. The general approach of designing buffer stops is via usage of the kinetic energy and its conversion into work. Paper describes input parameters such as train velocity or buffer stop vicinity which is expressed by the safety coefficient implanted within the calculation. Furthermore, the paper shows the principle of calculation the friction buffer stop work, or to be more precise, the work of its braking jaws and optionally the work of additional braking jaws located behind the buffer stop. Last section of the paper is focused on the examples of designing friction buffer stops, points out the main complications and shows the charts of relation amongst braking distance, kinetic energy and braking force and the charts of relation between deceleration rate and braking distance.

  6. Grip strength measured by high precision dynamometry in healthy subjects from 5 to 80 years.

    Science.gov (United States)

    Hogrel, Jean-Yves

    2015-06-10

    Grip strength is a variable which may be important to measure and follow in various populations. A new dynamometer with high accuracy and sensitivity has recently been developed to assess grip strength. The objectives of this work were to provide norms of maximal isometric grip strength measured with this new dynamometer (the MyoGrip device), to assess the reliability of measurements, to compare the measurements obtained with MyoGrip and Jamar dynamometers and finally to establish predictive equations from a population of healthy subjects (children and adults). Measurements of maximal isometric grip strength using the MyoGrip and the Jamar (which is considered as the gold-standard) were performed on 346 healthy subjects aged from 5 to 80 years. Test-retest reliability for both devices was assessed on 77 subjects. Predictive equations were computed on subjects younger than 60 years of age in order to avoid the effects of aging on strength. This study provides norms for isometric grip strength for health subjects from 5 to 80 years. Reliability of the MyoGrip device was excellent (intraclass correlation coefficient: 0.967). Despite good correlation between devices, the Jamar tended to overestimate maximal grip strength by about 14 %. A single predictive equation for men and women, adults and children incorporating hand circumference only can be used to compute the predicted theoretical maximal grip strength. The MyoGrip device is a reliable tool for measuring isometric grip strength. Owing to its unique metrological features, it can be used in very weak patients or in any situation where high precision and accuracy are required.

  7. Bioinspired orientation-dependent friction.

    Science.gov (United States)

    Xue, Longjian; Iturri, Jagoba; Kappl, Michael; Butt, Hans-Jürgen; del Campo, Aránzazu

    2014-09-23

    Spatular terminals on the toe pads of a gecko play an important role in directional adhesion and friction required for reversible attachment. Inspired by the toe pad design of a gecko, we study friction of polydimethylsiloxane (PDMS) micropillars terminated with asymmetric (spatular-shaped) overhangs. Friction forces in the direction of and against the spatular end were evaluated and compared to friction forces on symmetric T-shaped pillars and pillars without overhangs. The shape of friction curves and the values of friction forces on spatula-terminated pillars were orientation-dependent. Kinetic friction forces were enhanced when shearing against the spatular end, while static friction was stronger in the direction toward the spatular end. The overall friction force was higher in the direction against the spatula end. The maximum value was limited by the mechanical stability of the overhangs during shear. The aspect ratio of the pillar had a strong influence on the magnitude of the friction force, and its contribution surpassed and masked that of the spatular tip for aspect ratios of >2.

  8. Monitoring of bolt clamping force at high temperatures using metal-packaged regenerated fiber Bragg grating strain sensors

    Science.gov (United States)

    Huang, Yong-Kuo; Tu, Yun; Tu, Shan-Tung

    2017-10-01

    Insufficient or excessive preload has been regarded as the main issue that may endanger the safety of bolted joints operated at high temperatures. A new technique for monitoring the bolt clamping force is thus proposed using metal-packaged regenerated fiber Bragg grating (RFBG) strain sensors spot-welded onto the bolt. The measurement of the clamping force in a bolted steel-steel joint subjected to thermal loading is conducted. The experimental results show that the bolt clamping force can be monitored by the metal-packaged RFBG strain sensor at high temperatures up to 500 °C. This technique provides a new possibility for structural health monitoring of bolted joints operated at high temperatures.

  9. Impact of Nonlinearity of The Contact Layer Between Elements Joined in a Multi-Bolted System on Its Preload

    Science.gov (United States)

    Grzejda, R.

    2017-12-01

    The paper deals with modelling and calculations of asymmetrical multi-bolted joints at the assembly stage. The physical model of the joint is based on a system composed of four subsystems, which are: a couple of joined elements, a contact layer between the elements, and a set of bolts. The contact layer is assumed as the Winkler model, which can be treated as a nonlinear or linear model. In contrast, the set of bolts are modelled using simplified beam models, known as spider bolt models. The theorem according to which nonlinearity of the contact layer has a negligible impact on the final preload of the joint in the case of its sequential tightening has been verified. Results of sample calculations for the selected multi-bolted system, in the form of diagrams of preloads in the bolts as well as normal contact pressure between the joined elements during the assembly process and at its end, are presented.

  10. European development Rock bolting; Desarrollo Europeo del Bulonaje

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-11-01

    The project European Development Rockbolting which was developed during the period 1994-1997 and carried out within the OCICARBON Action Program (OCICARBON-ITGE agreement dated September 1, 1994, Code C-13-438) as well as within the framework of the Coal Technical research Program of the D. G. XVII of the EEC, n 7220/AB/143. The project has had the following external partners: DMT (Germany), BCC (UK) and CDF (France), and the collaboration of INERIS (France), RMT (UK) and GEOCONTROL S. A. (Spain). The objective of the investigation was to improve the techniques and design currently used in the application of rockbolts for supporting of both infrastructure and beds in the European coal mining. The most important result, besides that derived from the sharing of experiences and knowledge, was the technological design of a supporting system, which was carried out by each partner for the various proposed exploitations. The Spanish part carried out the works of designing and estimation of the bolting system corresponding to the exploitations of: -Carbones de Pedraforca SA. Saldes mine. -U. E. Provence. Pit Y. Morandat.

  11. Experimental study of snow friction

    Science.gov (United States)

    Cohen, Caroline; Canale, Luca; Siria, Alessandro; Quere, David; Bocquet, Lyderic; Clanet, Christophe

    2017-11-01

    Snow friction results from the interplay of different physical processes: solid friction of granular material, phase change and lubrication, heat transport, capillarity, elasticity and plasticity. The multiple conditions of temperature, humidity and density of the snow result in different regimes of friction. In particular, there is an optimal amount of melted water to lubricate the contact between the ski sole and the snow grains. The thickness of the water layer depends on temperature, speed... A huge variety of waxes have been empirically developed to adapt the amount of water to the conditions of skiing, but remain mysterious. In these study, we investigate experimentally the mechanisms of snow friction at different scales: first, the friction of a ski on snow is measured on a test bench, depending on the snow characteristics and for different waxes. Then microscopic experiments are led in order to understand the friction at the ice crystals scale.

  12. Friction surfaced Stellite6 coatings

    Energy Technology Data Exchange (ETDEWEB)

    Rao, K. Prasad; Damodaram, R. [Department of Metallurgical and Materials Engineering - Indian Institute of Technology Madras, Chennai 600 036 (India); Rafi, H. Khalid, E-mail: khalidrafi@gmail.com [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Ram, G.D. Janaki [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Reddy, G. Madhusudhan [Metal Joining Group, Defence Metallurgical Research Laboratory (DMRL) Kanchanbagh, Hyderabad 500 058 (India); Nagalakshmi, R. [Welding Research Institute, Bharat Heavy Electricals Limited, Tiruchirappalli 620 014 (India)

    2012-08-15

    Solid state Stellite6 coatings were deposited on steel substrate by friction surfacing and compared with Stellite6 cast rod and coatings deposited by gas tungsten arc and plasma transferred arc welding processes. Friction surfaced coatings exhibited finer and uniformly distributed carbides and were characterized by the absence of solidification structure and compositional homogeneity compared to cast rod, gas tungsten arc and plasma transferred coatings. Friction surfaced coating showed relatively higher hardness. X-ray diffraction of samples showed only face centered cubic Co peaks while cold worked coating showed hexagonally close packed Co also. - Highlights: Black-Right-Pointing-Pointer Stellite6 used as coating material for friction surfacing. Black-Right-Pointing-Pointer Friction surfaced (FS) coatings compared with casting, GTA and PTA processes. Black-Right-Pointing-Pointer Finer and uniformly distributed carbides in friction surfaced coatings. Black-Right-Pointing-Pointer Absence of melting results compositional homogeneity in FS Stellite6 coatings.

  13. Friction surfaced Stellite6 coatings

    International Nuclear Information System (INIS)

    Rao, K. Prasad; Damodaram, R.; Rafi, H. Khalid; Ram, G.D. Janaki; Reddy, G. Madhusudhan; Nagalakshmi, R.

    2012-01-01

    Solid state Stellite6 coatings were deposited on steel substrate by friction surfacing and compared with Stellite6 cast rod and coatings deposited by gas tungsten arc and plasma transferred arc welding processes. Friction surfaced coatings exhibited finer and uniformly distributed carbides and were characterized by the absence of solidification structure and compositional homogeneity compared to cast rod, gas tungsten arc and plasma transferred coatings. Friction surfaced coating showed relatively higher hardness. X-ray diffraction of samples showed only face centered cubic Co peaks while cold worked coating showed hexagonally close packed Co also. - Highlights: ► Stellite6 used as coating material for friction surfacing. ► Friction surfaced (FS) coatings compared with casting, GTA and PTA processes. ► Finer and uniformly distributed carbides in friction surfaced coatings. ► Absence of melting results compositional homogeneity in FS Stellite6 coatings.

  14. A Component-Based Study of the Effect of Diameter on Bond and Anchorage Characteristics of Blind-Bolted Connections.

    Directory of Open Access Journals (Sweden)

    Muhammad Nasir Amin

    Full Text Available Structural hollow sections are gaining worldwide importance due to their structural and architectural advantages over open steel sections. The only obstacle to their use is their connection with other structural members. To overcome the obstacle of tightening the bolt from one side has given birth to the concept of blind bolts. Blind bolts, being the practical solution to the connection hindrance for the use of hollow and concrete filled hollow sections play a vital role. Flowdrill, the Huck High Strength Blind Bolt and the Lindapter Hollobolt are the well-known commercially available blind bolts. Although the development of blind bolts has largely resolved this issue, the use of structural hollow sections remains limited to shear resistance. Therefore, a new modified version of the blind bolt, known as the "Extended Hollo-Bolt" (EHB due to its enhanced capacity for bonding with concrete, can overcome the issue of low moment resistance capacity associated with blind-bolted connections. The load transfer mechanism of this recently developed blind bolt remains unclear, however. This study uses a parametric approach to characterising the EHB, using diameter as the variable parameter. Stiffness and load-carrying capacity were evaluated at two different bolt sizes. To investigate the load transfer mechanism, a component-based study of the bond and anchorage characteristics was performed by breaking down the EHB into its components. The results of the study provide insight into the load transfer mechanism of the blind bolt in question. The proposed component-based model was validated by a spring model, through which the stiffness of the EHB was compared to that of its components combined. The combined stiffness of the components was found to be roughly equivalent to that of the EHB as a whole, validating the use of this component-based approach.

  15. The effect of cultivar, sowing date and transplant location in field on bolting of Welsh onion (Allium fistulosum L.)

    Science.gov (United States)

    2013-01-01

    Background Bolting reduces the quality and commercial yield of Welsh onion (Allium fistulosum L.) in production. However, seed production is directly dependent on flower induction and bolting. The Welsh onion belongs to the green plant vernalisation type, specific seedling characteristics and sufficient accumulated time at low temperature are indispensible for the completion of its vernalisation process. Only if these conditions for vernalisation are fulfilled, the plants will bolt in the following year. The present investigation evaluated the effects of cultivar, sowing date and transplant location in field on the bolting of Welsh onion at the Horticultural Farm of the College of Horticulture, Northwest A&F University, Yangling, Shannxi Province, China in two succeeding production years: 2010–2011 and 2011–2012. A strip split plot layout within a randomised complete block design with three replications was used. Results The results revealed that all three factors (cultivar, sowing date and transplant location) and their interaction had significant effects on the initiation and final rate of bolting observed by 30 April. The earliest bolting date (14 February, 2011 and 15 February, 2012) and the highest bolting rate (100% in 2011 and 62% in 2012) occurred when the JinGuan cultivar was sown on 20 August and transplanted in a plastic tunnel, whereas the latest date and lowest rate (no bolting observed until 30 April) of bolting occurred when the XiaHei cultivar was sown on 29 September and transplanted in an open field. Conclusions These results suggest that we can control bolting in Welsh onion production by choosing an appropriate cultivar, sowing date and transplant location. Choosing a late bolting cultivar, such as cultivar XiaHei, sowing around October, and transplanting in the open field can significantly delay bolting, while a sowing date in late August should be selected for seed production, and the seedlings should be transplanted in a plastic tunnel to

  16. Muscle strength: clinical and prognostic value of hand-grip dynamometry.

    Science.gov (United States)

    Bohannon, Richard W

    2015-09-01

    Grip strength measured by dynamometry is well established as an indicator of muscle status, particularly among older adults. This review was undertaken to provide a synopsis of recent literature addressing the clinical and prognostic value of hand-grip dynamometry. Numerous large-scale normative grip strength projects have been published lately. Other recent studies have reinforced the concurrent relationship of grip strength with measures of nutritional status or muscle mass and measures of function and health status. Studies published in the past few years have confirmed the value of grip strength as a predictor of mortality, hospital length of stay, and physical functioning. As a whole, the recent literature supports the use of hand-grip dynamometry as a fundamental element of the physical examination of patients, particularly if they are older adults.

  17. Discrimination of handlebar grip samples by fourier transform infrared microspectroscopy analysis and statistics

    Directory of Open Access Journals (Sweden)

    Zeyu Lin

    2017-01-01

    Full Text Available In this paper, the authors presented a study on the discrimination of handlebar grip samples, to provide effective forensic science service for hit and run traffic cases. 50 bicycle handlebar grip samples, 49 electric bike handlebar grip samples, and 96 motorcycle handlebar grip samples have been randomly collected by the local police in Beijing (China. Fourier transform infrared microspectroscopy (FTIR was utilized as analytical technology. Then, target absorption selection, data pretreatment, and discrimination of linked samples and unlinked samples were chosen as three steps to improve the discrimination of FTIR spectrums collected from different handlebar grip samples. Principal component analysis and receiver operating characteristic curve were utilized to evaluate different data selection methods and different data pretreatment methods, respectively. It is possible to explore the evidential value of handlebar grip residue evidence through instrumental analysis and statistical treatments. It will provide a universal discrimination method for other forensic science samples as well.

  18. Micromechanical study of macroscopic friction and dissipation in idealised granular materials: the effect of interparticle friction

    NARCIS (Netherlands)

    Kruyt, Nicolaas P.; Gutkowski, Witold; Rothenburg, L.; Kowalewski, Tomasz A.

    2004-01-01

    Using Discrete Element Method (DEM) simulations with varying interparticle friction coefficient, the relation between interparticle friction coefficient and macroscopic continuum friction and dissipation is investigated. As expected, macroscopic friction and dilatancy increase with interparticle

  19. FE-MODELLING OF A CONTACT LAYER BETWEEN ELEMENTS JOINED IN PRELOADED BOLTED CONNECTIONS FOR THE OPERATIONAL CONDITION

    Directory of Open Access Journals (Sweden)

    Rafał Grzejda

    2014-11-01

    Full Text Available Modelling and calculations of a contact layer between elements joined in a preloaded bolted connection for the operational condition are presented. The physical model of the bolted connection is based on a flexible flange element that is joined with a rigid support by means of the no-bolt model (at the assembly stage or the rigid body bolt model (at the operational stage. The contact layer between joined elements is described as the nonlinear Winkler model. The contact joint model considering an experimental normal elastic characteristic is presented. Examples of normal contact pressure and normal contact deformations distributions are contained.

  20. Transcriptomic analysis identifies differentially expressed genes (DEGs associated with bolting and flowering in radish (Raphanus sativus L.

    Directory of Open Access Journals (Sweden)

    Shanshan eNie

    2016-05-01

    Full Text Available AbstractThe transition of vegetative growth to bolting and flowering is an important process in the life cycle of plants, which is determined by numerous genes forming an intricate network of bolting and flowering. However, no comprehensive identification and profiling of bolting and flowering-related genes have been carried out in radish. In this study, RNA-seq technology was applied to analyze the differential gene expressions during the transition from vegetative stage to reproductive stage in radish. A total of 5,922 differentially expressed genes (DEGs including 779 up-regulated and 5,143 down-regulated genes were isolated. Functional enrichment analysis suggested that some DEGs were involved in hormone signaling pathways and the transcriptional regulation of bolting and flowering. KEGG-based analysis identified 37 DEGs being involved in phytohormone signaling pathways. Moreover, 95 DEGs related to bolting and flowering were identified and integrated into various flowering pathways. Several critical genes including FT, CO, SOC1, FLC and LFY were characterized and profiled by RT-qPCR analysis. Correlation analysis indicated that 24 miRNA-DEG pairs were involved in radish bolting and flowering. Finally, a miRNA-DEG-based schematic model of bolting and flowering regulatory network was proposed in radish. These outcomes provided significant insights into genetic control of radish bolting and flowering, and would facilitate unraveling molecular regulatory mechanism underlying bolting and flowering in root vegetable crops.

  1. Argo packing friction research update

    International Nuclear Information System (INIS)

    VanTassell, D.M.

    1994-01-01

    This paper focuses on the issue of valve packing friction and its affect on the operability of motor- and air-operated valves (MOVs and AOVs). At this time, most nuclear power plants are required to perform postmaintenance testing following a packing adjustment or replacement. In many cases, the friction generated by the packing does not impact the operability window of a valve. However, to date there has not been a concerted effort to substantiate this claim. To quantify the effects of packing friction, it has become necessary to develop a formula to predict the friction effects accurately. This formula provides a much more accurate method of predicting packing friction than previously used factors based strictly on stem diameter. Over the past 5 years, Argo Packing Company has been developing and testing improved graphite packing systems at research facilities, such as AECL Chalk River and Wyle Laboratories. Much of this testing has centered around reducing and predicting friction that is related to packing. In addition, diagnostic testing for Generic Letter 89-10 MOVs and AOVs has created a significant data base. In July 1992 Argo asked several utilities to provide running load data that could be used to quantify packing friction repeatability and predictability. This technical paper provides the basis to predict packing friction, which will improve calculations for thrust requirements for Generic Leter 89-10 and future AOV programs. In addition, having an accurate packing friction formula will improve packing performance when low running loads are identified that would indicate insufficient sealing force

  2. Friction and wear calculation methods

    CERN Document Server

    Kragelsky, I V; Kombalov, V S

    1981-01-01

    Friction and Wear: Calculation Methods provides an introduction to the main theories of a new branch of mechanics known as """"contact interaction of solids in relative motion."""" This branch is closely bound up with other sciences, especially physics and chemistry. The book analyzes the nature of friction and wear, and some theoretical relationships that link the characteristics of the processes and the properties of the contacting bodies essential for practical application of the theories in calculating friction forces and wear values. The effect of the environment on friction and wear is a

  3. Internal friction in enzyme reactions.

    Science.gov (United States)

    Rauscher, Anna; Derényi, Imre; Gráf, László; Málnási-Csizmadia, András

    2013-01-01

    The empirical concept of internal friction was introduced 20 years ago. This review summarizes the results of experimental and theoretical studies that help to uncover the nature of internal friction. After the history of the concept, we describe the experimental challenges in measuring and interpreting internal friction based on the viscosity dependence of enzyme reactions. We also present speculations about the structural background of this viscosity dependence. Finally, some models about the relationship between the energy landscape and internal friction are outlined. Alternative concepts regarding the viscosity dependence of enzyme reactions are also discussed. Copyright © 2012 International Union of Biochemistry and Molecular Biology, Inc.

  4. GRIPS-Gamma-Ray burst Investigation via Polarimetry and Spectroscopy

    International Nuclear Information System (INIS)

    Greiner, J.

    2008-01-01

    The primary scientific goal of the GRIPS mission [1] is to revolutionize our understanding of the early universe using γ-ray bursts. We propose a new generation gamma-ray observatory capable of unprecedented spectroscopy over a wide range of γ-ray energies (200 keV-50 MeV) and of polarimetry (200-1000 keV). Secondary goals achievable by this mission include direct measurements of supernova interiors through γ-rays from radioactive decays, nuclear astrophysics with massive stars and novae, and studies of particle acceleration near compact stars, interstellar shocks, and clusters of galaxies

  5. Event-related brain potentials for goal-related power grips.

    Science.gov (United States)

    Westerholz, Jan; Schack, Thomas; Koester, Dirk

    2013-01-01

    Recent research has shown that neurophysiological activation during action planning depends on the orientation to initial or final action goals for precision grips. However, the neural signature for a distinct class of grasping, power grips, is still unknown. The aim of the present study was to differentiate between cerebral activity, by means of event-related potentials (ERPs), and its temporal organization during power grips executed with an emphasis on either the initial or final parts of movement sequences. In a grasp and transportation task, visual cues emphasized either the grip (the immediate goal) or the target location (the final goal). ERPs differed between immediate and final goal-cued conditions, suggesting different means of operation dependent on goal-relatedness. Differences in mean amplitude occurred earlier for power grips than for recently reported precision grips time-locked to grasping over parieto-occipital areas. Time-locked to final object placement, differences occurred within a similar time window for power and precision grips over frontal areas. These results suggest that a parieto-frontal network of activation is of crucial importance for grasp planning and execution. Our results indicate that power grip preparation and execution for goal-related actions are controlled by similar neural mechanisms as have been observed during precision grips, but with a distinct temporal pattern.

  6. Effects of hand grip exercise on shoulder joint internal rotation and external rotation peak torque.

    Science.gov (United States)

    Lee, Dong-Rour; Jong-Soon Kim, Laurentius

    2016-08-10

    The goal of this study is to analyze the effects of hand grip training on shoulder joint internal rotation (IR)/external rotation (ER) peak torque for healthy people. The research was conducted on 23 healthy adults in their 20 s-30 s who volunteered to participate in the experiment. Hand grip power test was performed on both hands of the research subjects before/after the test to study changes in hand grip power. Isokinetic machine was used to measure the concentric IRPT (internal rotation peak torque) and concentric ERPT (external rotation peak torque) at the velocity of 60°/sec, 90°/sec, and 180°/sec before/after the test. Hand grip training was performed daily on the subject's right hand only for four weeks according to exercise program. Finally, hand grip power of both hands and the maximum torque values of shoulder joint IR/ER were measured before/after the test and analyzed. There was a statistically significant difference in the hand grip power of the right hand, which was subject to hand grip training, after the experiment. Also, statistically significant difference for shoulder ERPT was found at 60°/sec. Hand grip training has a positive effect on shoulder joint IRPT/ERPT and therefore can help strengthen muscles around the shoulder without using weight on the shoulder. Consequently, hand grip training would help maintain strengthen the muscles around the shoulder in the early phase of rehabilitation process after shoulder surgery.

  7. Delayed grip relaxation and altered modulation of intracortical inhibition with aging

    Science.gov (United States)

    Motawar, Binal; Stinear, James W.; Lauer, Abigail W.; Ramakrishnan, V. Viswanathan; Seo, Na Jin

    2015-01-01

    Grip relaxation is a voluntary action that requires an increase in short-interval intracortical inhibition (SICI) in healthy young adults, rather than a simple termination of excitatory drive. The way aging affects this voluntary inhibitory action and timing of grip relaxation is currently unknown. The objective of this study was to examine aging-related delays in grip relaxation and SICI modulation for the flexor digitorum superficialis (FDS) muscle during grip relaxation. The main finding was that young adults increased SICI to relax their grips, whereas older adults did not increase SICI with a prolonged grip relaxation time (prelaxation time). A secondary experiment showed that both young and older adults did not change H reflex excitability during grip relaxation. Our data suggest that grip relaxation is mediated by increased cortical inhibitory output in young adults, and aging-related impairment in increasing cortical inhibitory output may hamper timely cessation of muscle activity. Our data also suggest a lesser role of the spinal circuits in grip muscle relaxation. This knowledge may contribute to understanding of aging-related movement deterioration and development of interventions for improving modulation of SICI to improve muscle relaxation and movement coordination. PMID:26686531

  8. Understanding Friction Stir Welding

    Science.gov (United States)

    Nunes, A. C., Jr.

    2018-01-01

    This Technical Memorandum explains the friction stir welding process in terms of two basic concepts: the concentration of deformation in a shear surface enveloping the tool and the composition of the overall plastic flow field around the tool from simple flow field components. It is demonstrated how weld structure may be understood and torque, drag, and lateral tool forces may be estimated using these concepts. Some discrepancies between computations and accompanying empirical data are discussed in the text. This work is intended to be helpful to engineers in diagnosing problems and advancing technology.

  9. Brachistochrone with Coulomb friction

    Science.gov (United States)

    Hayen, J.

    2005-10-01

    The classical brachistochrone is considered with the inclusion of a resistant force, which is due to Coulomb friction, in addition to the uniform gravitational force that is present. The solution to this problem is expressed in terms of standard functions, and it is developed in two separate ways by means of constrained variational calculus methods. These ways involve formulations of the problem in terms of temporal and spatial independent variables, respectively. The equations of motion that result in both cases are non-linear and coupled. The utilization of path variables is a central feature of the developments provided.

  10. Frictional behaviour of high performance fibrous tows: Friction experiments

    NARCIS (Netherlands)

    Cornelissen, Bo; Rietman, Bert; Akkerman, Remko

    2013-01-01

    Tow friction is an important mechanism in the production and processing of high performance fibrous tows. The frictional behaviour of these tows is anisotropic due to the texture of the filaments as well as the tows. This work describes capstan experiments that were performed to measure the

  11. Friction analysis of kinetic schemes : the friction coefficient

    NARCIS (Netherlands)

    Lolkema, Juke S.

    1995-01-01

    Friction analysis is proposed as the application of general control analysis to single enzymes to describe the control of elementary kinetic steps on the overall catalytic rate. For each transition, a friction coefficient is defined that measures the sensitivity of the turnover rate to the free

  12. General theory of frictional heating with application to rubber friction

    Science.gov (United States)

    Fortunato, G.; Ciaravola, V.; Furno, A.; Lorenz, B.; Persson, B. N. J.

    2015-05-01

    The energy dissipation in the contact regions between solids in sliding contact can result in high local temperatures which may strongly effect friction and wear. This is the case for rubber sliding on road surfaces at speeds above 1 mm s-1. We derive equations which describe the frictional heating for solids with arbitrary thermal properties. The theory is applied to rubber friction on road surfaces and we take into account that the frictional energy is partly produced inside the rubber due to the internal friction of rubber and in a thin (nanometer) interfacial layer at the rubber-road contact region. The heat transfer between the rubber and the road surface is described by a heat transfer coefficient which depends on the sliding speed. Numerical results are presented and compared to experimental data. We find that frictional heating results in a kinetic friction force which depends on the orientation of the sliding block, thus violating one of the two basic Leonardo da Vinci ‘laws’ of friction.

  13. Friction Stir Welding

    Science.gov (United States)

    Nunes, Arthur C., Jr.

    2008-01-01

    Friction stir welding (FSW) is a solid state welding process invented in 1991 at The Welding Institute in the United Kingdom. A weld is made in the FSW process by translating a rotating pin along a weld seam so as to stir the sides of the seam together. FSW avoids deleterious effects inherent in melting and promises to be an important welding process for any industries where welds of optimal quality are demanded. This article provides an introduction to the FSW process. The chief concern is the physical effect of the tool on the weld metal: how weld seam bonding takes place, what kind of weld structure is generated, potential problems, possible defects for example, and implications for process parameters and tool design. Weld properties are determined by structure, and the structure of friction stir welds is determined by the weld metal flow field in the vicinity of the weld tool. Metal flow in the vicinity of the weld tool is explained through a simple kinematic flow model that decomposes the flow field into three basic component flows: a uniform translation, a rotating solid cylinder, and a ring vortex encircling the tool. The flow components, superposed to construct the flow model, can be related to particular aspects of weld process parameters and tool design; they provide a bridge to an understanding of a complex-at-first-glance weld structure. Torques and forces are also discussed. Some simple mathematical models of structural aspects, torques, and forces are included.

  14. Comparative study of maximum isometric grip strength in different sports

    Directory of Open Access Journals (Sweden)

    Noé Gomes Borges Junior

    2009-06-01

    Full Text Available The objective of this study was to compare maximum isometric grip strength (Fmaxbetween different sports and between the dominant (FmaxD and non-dominant (FmaxND hand. Twenty-nine male aikido (AI, jiujitsu (JJ, judo (JU and rowing (RO athletes and 21non-athletes (NA participated in the study. The hand strength test consisted of maintainingmaximum isometric grip strength for 10 seconds using a hand dynamometer. The position of the subjects was that suggested by the American Society of Hand Therapy. Factorial 2X5 ANOVA with Bonferroni correction, followed by a paired t test and Tukey test, was used for statistical analysis. The highest Fmax values were observed for the JJ group when using the dominant hand,followed by the JU, RO, AI and NA groups. Variation in Fmax could be attributed to handdominance (30.9%, sports modality (39.9% and the interaction between hand dominance andsport (21.3%. The present results demonstrated significant differences in Fmax between the JJ and AI groups and between the JJ and NA groups for both the dominant and non-dominant hand. Significant differences in Fmax between the dominant and non-dominant hand were only observed in the AI and NA groups. The results indicate that Fmax can be used for comparisonbetween different sports modalities, and to identify differences between the dominant and nondominanthand. Studies involving a larger number of subjects will permit the identification of differences between other modalities.

  15. International Space Station Powered Bolt Nut Anomaly and Failure Analysis Summary

    Science.gov (United States)

    Sievers, Daniel E.; Warden, Harry K.

    2010-01-01

    A key mechanism used in the on-orbit assembly of the International Space Station (ISS) pressurized elements is the Common Berthing Mechanism. The mechanism that effects the structural connection of the Common Berthing Mechanism halves is the Powered Bolt Assembly. There are sixteen Powered Bolt Assemblies per Common Berthing Mechanism. The Common Berthing Mechanism has a bolt which engages a self aligning Powered Bolt Nut (PBN) on the mating interface (Figure 1). The Powered Bolt Assemblies are preloaded to approximately 84.5 kN (19000 lb) prior to pressurization of the CBM. The PBNs mentioned below, manufactured in 2009, will be used on ISS future missions. An on orbit functional failure of this hardware would be unacceptable and in some instances catastrophic due to the failure of modules to mate and seal the atmosphere, risking loss of crew and ISS functions. The manufacturing processes that create the PBNs need to be strictly controlled. Functional (torque vs. tension) acceptance test failures will be the result of processes not being strictly followed. Without the proper knowledge of thread tolerances, fabrication techniques, and dry film lubricant application processes, PBNs will be, and have been manufactured improperly. The knowledge gained from acceptance test failures and the resolution of those failures, thread fabrication techniques and thread dry film lubrication processes can be applied to many aerospace mechanisms to enhance their performance. Test data and manufactured PBN thread geometry will be discussed for both failed and successfully accepted PBNs.

  16. Corrosion monitoring of rock bolt by using a low coherent fiber-optic interferometry

    Science.gov (United States)

    Wei, Heming; Zhao, Xuefeng; Li, Dongsheng; Zhang, Pinglei; Sun, Changsen

    2015-04-01

    Corrosion of rock bolts is a major cause for deterioration of the anchor-reinforced concrete slopes structures. In order to evaluate this corrosion-based deterioration in an early stage, a nondestructive technique was required. However, until now, there are no commercialized solutions that are straightforwardly available. Here, a low-coherent fiber-optic sensing technique was developed. This method can carry out the monitoring of the corrosion-caused expansion at the accuracy of sub-microstrains by circled the sensing optical fiber in two ways. One was wound the fiber on the surface of steel rock bolt directly, and thereby generated a nonuniformity in the interface of cement with rock bolt. The other was circled the fiber on a cement mortar cushion without destroying the interface any way. The sensing fiber was configured as one arm of the fiber-optic Michelson interferometer. The acceleration corrosion experiments demonstrated that a uniform interface between cement and rock bolt determined the progress of corrosion development. An early stage evaluation of the corrosion development in rock bolts was monitored.

  17. Evaluation of the clamping force in high tension bolt by using the ultrasonic nonlinearity

    International Nuclear Information System (INIS)

    Jang, Kyung Young; Cheon, Hae Wha; Ha, Hob; Park, Man Sick; Kim, No You

    2005-01-01

    High tension bolts have been used widely for the clamping of many kinds of large structure. Therefore, its estimation has been regarded as main issue in the maintenance of high tension bolts. This paper proposes a novel method using the ultrasonic nonlinearity, which is based on the dependency of sound speed on the stress. For this we introduce nonlinear elastic constants in the stress-strain relationship, and derive the sound speed as a linear function of stress. In order to verify the usefulness of the proposed method, two kinds of experiments are carried out: The first one is to measure the sound speed when the bolt is stressed by the tension tester. The result showed good agreement with the expected linear relationship between the sound speed and the axial stress. The second one is to measure the sound speed when the bolt is stressed by the torque wrench. The results showed that the sound speed was decreased when the torque was increased. From these results we can say that the proposed method is enough useful to evaluate the clamping force in the high tension bolt.

  18. Numerical Study on Ultimate Behaviour of Bolted End-Plate Steel Connections

    Directory of Open Access Journals (Sweden)

    R.E.S. Ismail

    Full Text Available Abstract Bolted end-plate steel connections have become more popular due to ease of fabrication. This paper presents a three dimension Finite Element Model (FEM, using the multi-purpose software ABAQUS, to study the effect of different geometrical parameters on the ultimate behavior of the connection. The proposed model takes into account material and geometrical non-linearities, initial imperfection, contact between adjacent surfaces and the pretension force in the bolts. The Finite Element results are calibrated with published experimental results ''briefly reviewed in this paper'' and verified that the numerical model can simulate and analyze the overall and detailed behavior of different types of bolted end-plate steel connections. Using verified FEM, parametric study is then carried out to study the ultimate behavior with variations in: bolt diameter, end-plate thickness, length of column stiffener, angle of rib stiffener. The results are examined with respect to the failure modes, the evolution of the resistance, the initial stiffness, and the rotation capacity. Finally, the ultimate behavior of the bolted end-plate steel connection is discussed in detail, and recommendations for the design purpose are made.

  19. Nonlinear Modeling and Identification of an Aluminum Honeycomb Panel with Multiple Bolts

    Directory of Open Access Journals (Sweden)

    Yongpeng Chu

    2016-01-01

    Full Text Available This paper focuses on the nonlinear dynamics modeling and parameter identification of an Aluminum Honeycomb Panel (AHP with multiple bolted joints. Finite element method using eight-node solid elements is exploited to model the panel and the bolted connection interface as a homogeneous, isotropic plate and as a thin layer of nonlinear elastic-plastic material, respectively. The material properties of a thin layer are defined by a bilinear elastic plastic model, which can describe the energy dissipation and softening phenomena in the bolted joints under nonlinear states. Experimental tests at low and high excitation levels are performed to reveal the dynamic characteristics of the bolted structure. In particular, the linear material parameters of the panel are identified via experimental tests at low excitation levels, whereas the nonlinear material parameters of the thin layer are updated by using the genetic algorithm to minimize the residual error between the measured and the simulation data at a high excitation level. It is demonstrated by comparing the frequency responses of the updated FEM and the experimental system that the thin layer of bilinear elastic-plastic material is very effective for modeling the nonlinear joint interface of the assembled structure with multiple bolts.

  20. PIXE Analysis of Metal Hull Bolts From HMB DeBraak

    International Nuclear Information System (INIS)

    Correll, Francis D.; Cole, Lord K.; Slater, Charles J.; Vanhoy, Jeffrey R.; Fithian, Charles H.

    2009-01-01

    HMB DeBraak was a 16-gun British brig-sloop that sank in a squall on May 25, 1798 off Cape Henlopen, Delaware. Silt covered the wooden hull shortly after it sank, preserving it until DeBraak was raised in 1986. The items recovered from the ship include metal bolts that held the hull together. We used PIXE to measure the compositions of 45 of the bolts and found that they are nearly pure copper (98.3% on average), with most also containing small amounts of iron (0.87%), nickel (0.039%), arsenic (0.43%), silver (0.089%), lead (0.18%), and bismuth (0.12%). A few contain a little indium, tin, or antimony, but none contain zinc above the quantization level. The compositions are similar to those reported for 18th-century English copper, but different from several copper alloys also used to make hull bolts. We conclude that, when DeBraak was last fitted out in 1795-1797, the Royal Navy was still using bolts similar to William Forbes's mechanically hardened pure copper bolts. Forbes's process represents the successful innovation and application of new technology in Royal Navy ships during the wars of the late 18th century.

  1. Interferometric Observations of a Bolt from the Blue

    Science.gov (United States)

    Stock, M.; Lapierre, J. L.; Krehbiel, P. R.; Stanley, M. A.; Rison, W.; Edens, H. E.

    2013-12-01

    A continuous-sampling, broadband VHF Digital Interferometer (DITF) has been operated at Langmuir Laboratory in New Mexico since 2011. For the 2013 storm season, a number of upgrades have been made to the DITF to increase the dynamic range of its front end receiver, allow for the recording of pretrigger data, and improve the trigger efficiency. The result of these upgrades are high quality interferometric maps of lightning having sub-microsecond time resolution, showing details of the physical processes within lightning flashes that previously have been difficult to observe. As an example of the DITF's data, a hybrid negative cloud-to-ground flash from a storm on July 8, 2013 is examined in detail. The flash was a classic bolt-from-the-blue that began with upward negative breakdown into upper positive storm charge, then traveled several kilometers horizontally and directly over top of the interferometer site before exiting the side of the storm and turning downward toward ground as a stepped leader. Due to the large horizontal displacement between the positive and negative ends of the breakdown channels, and to its close proximity to the interferometer site, this flash makes for an ideal case study of several different physical processes in lightning flashes including: the characteristics and properties of the positive incloud breakdown prior to and following the initial return stroke, negative leader propagation into the upper positive charge region and subsequent alteration of the leader as it progressed downward toward ground, and retrograde negative breakdown processes along the positive leader channels leading to the development of dart leaders and subsequent strokes to ground. The high time resolution of the interferometric maps makes it possible to present these processes as high quality animations similar to *those* of high speed optical observations.

  2. Friction Testing of Thermoplastic Composites

    NARCIS (Netherlands)

    Sachs, Ulrich; Haanappel, Sebastiaan; Rietman, Bert; Akkerman, Remko; Erath, Mark A.

    2011-01-01

    Friction phenomena play a major role in thermoplastic composite forming processes. In order to make use of the large potential these materials have, accurate CAE tools are needed that as a consequence incorporate temperature, pressure and velocity dependent friction behavior. To obtain a sound

  3. Corrosion effects on friction factors

    International Nuclear Information System (INIS)

    Magleby, H.L.; Shaffer, S.J.

    1996-01-01

    This paper presents the results of NRC-sponsored material specimen tests that were performed to determine if corrosion increases the friction factors of sliding surfaces of motor-operated gate valves, which could require higher forces to close and open safety-related valves when subjected to their design basis differential pressures. Friction tests were performed with uncorroded specimens and specimens subjected to accelerated corrosion. Preliminary tests at ambient conditions showed that corrosion increased the friction factors, indicating the need for additional tests duplicating valve operating parameters at hot conditions. The additional tests showed friction factors of corroded specimens were 0.1 to 0.2 higher than for uncorroded specimens, and that the friction factors of the corroded specimens were not very dependent on contact stress or corrosion film thickness. The measured values of friction factors for the three corrosion films tested (simulating three operating times) were in the range of 0.3 to 0.4. The friction factor for even the shortest simulated operating time was essentially the same as the others, indicating that the friction factors appear to reach a plateau and that the plateau is reached quickly

  4. Friction of atomically stepped surfaces

    NARCIS (Netherlands)

    Dikken, R.J.; Thijsse, B.J.; Nicola, L.

    2017-01-01

    The friction behavior of atomically stepped metal surfaces under contact loading is studied using molecular dynamics simulations. While real rough metal surfaces involve roughness at multiple length scales, the focus of this paper is on understanding friction of the smallest scale of roughness:

  5. Blades Couple Dry Friction Connection

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk; Radolfová, Alena

    2015-01-01

    Roč. 9, č. 1 (2015), s. 31-40 ISSN 1802-680X Institutional support: RVO:61388998 Keywords : stick-slip dry friction * 3D friction characteristic * tangential contact stiffness * hysterezis loop * response curves Subject RIV: BI - Acoustics

  6. Computational model of precision grip in Parkinson’s disease: A Utility based approach

    Directory of Open Access Journals (Sweden)

    Ankur eGupta

    2013-12-01

    Full Text Available We propose a computational model of Precision Grip (PG performance in normal subjects and Parkinson’s Disease (PD patients. Prior studies on grip force generation in PD patients show an increase in grip force during ON medication and an increase in the variability of the grip force during OFF medication (Fellows et al 1998; Ingvarsson et al 1997. Changes in grip force generation in dopamine-deficient PD conditions strongly suggest contribution of the Basal Ganglia, a deep brain system having a crucial role in translating dopamine signals to decision making. The present approach is to treat the problem of modeling grip force generation as a problem of action selection, which is one of the key functions of the Basal Ganglia. The model consists of two components: 1 the sensory-motor loop component, and 2 the Basal Ganglia component. The sensory-motor loop component converts a reference position and a reference grip force, into lift force and grip force profiles, respectively. These two forces cooperate in grip-lifting a load. The sensory-motor loop component also includes a plant model that represents the interaction between two fingers involved in PG, and the object to be lifted. The Basal Ganglia component is modeled using Reinforcement Learning with the significant difference that the action selection is performed using utility distribution instead of using purely Value-based distribution, thereby incorporating risk-based decision making. The proposed model is able to account for the precision grip results from normal and PD patients accurately (Fellows et. al. 1998; Ingvarsson et. al. 1997. To our knowledge the model is the first model of precision grip in PD conditions.

  7. Effects of grip width on muscle strength and activation in the lat pull-down.

    Science.gov (United States)

    Andersen, Vidar; Fimland, Marius S; Wiik, Espen; Skoglund, Anders; Saeterbakken, Atle H

    2014-04-01

    The lat pull-down is one of the most popular compound back exercises. Still, it is a general belief that a wider grip activates the latissimus dorsi more than a narrow one, but without any broad scientific support. The aim of the study was to compare 6 repetition maximum (6RM) load and electromyographic (EMG) activity in the lat pull-down using 3 different pronated grip widths. Fifteen men performed 6RM in the lat pull-down with narrow, medium, and wide grips (1, 1.5, and 2 times the biacromial distance) in a randomized and counterbalanced order. The 6RM strengths with narrow (80.3 ± 7.2 kg) and medium grip (80 ± 7.1 kg) were higher than wide grip (77.3 ± 6.3 kg; p = 0.02). There was similar EMG activation between grip widths for latissimus, trapezius, or infraspinatus, but a tendency for biceps brachii activation to be greater for medium vs. narrow (p = 0.09), when the entire movement was analyzed. Analyzing the concentric phase separately revealed greater biceps brachii activation using the medium vs. narrow grip (p = 0.03). In the eccentric phase, there was greater activation using wide vs. narrow grip for latissimus and infraspinatus (p ≤ 0.04), and tendencies for medium greater than narrow for latissimus, and medium greater than wide for biceps (both p = 0.08), was observed. Collectively, a medium grip may have some minor advantages over small and wide grips; however, athletes and others engaged in resistance training can generally expect similar muscle activation which in turn should result in similar hypertrophy gains with a grip width that is 1-2 times the biacromial distance.

  8. Comparative study of millennials' (age 20-34 years) grip and lateral pinch with the norms.

    Science.gov (United States)

    Fain, Elizabeth; Weatherford, Cara

    Cross-sectional research design. Clinical practice continues to use normative data for grip and pinch measurements that were established in 1985. There is no updated norms despite different hand usage patterns in today's society. Measuring and comparing grip and pinch strengths with normative data is a valid method to determine hand function. This research was implemented to compare the grip and pinch measurements obtained from healthy millennials to the established norms and to describe hand usage patterns for millennials. Grip and lateral pinch measurements were obtained from a sample of 237 healthy millennials (ages 20-34 years). Strength scores were statistically lower that older normative data in all millennial grip strengths, with the exception of the women in the age group of 30-34 years. Specifically, this statistically significant trend was observed in all male grip strengths, as well as in women in the age group of 20-24 years (bilateral grip) and 25-29 years (right grip). However, the lateral pinch data reflected was similar to the older norms with variances of 0.5-1 kg. Current data reflect statistically significant differences from the norms for all male grip measurements, as well as for women in the age group of 20-24 years (bilateral grip) and 25-29 years (right grip). No statistical significance was observed in the independent-sample t tests for the lateral pinch in men of all age groups. Statistical significance was noted for lateral pinch for female age groups for the left hand (20-24 years) and for bilateral lateral pinches (30-34 years). IV. Copyright © 2016 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

  9. Nanoscale friction and wear maps.

    Science.gov (United States)

    Tambe, Nikhil S; Bhushan, Bharat

    2008-04-28

    Friction and wear are part and parcel of all walks of life, and for interfaces that are in close or near contact, tribology and mechanics are supremely important. They can critically influence the efficient functioning of devices and components. Nanoscale friction force follows a complex nonlinear dependence on multiple, often interdependent, interfacial and material properties. Various studies indicate that nanoscale devices may behave in ways that cannot be predicted from their larger counterparts. Nanoscale friction and wear mapping can help identify some 'sweet spots' that would give ultralow friction and near-zero wear. Mapping nanoscale friction and wear as a function of operating conditions and interface properties is a valuable tool and has the potential to impact the very way in which we design and select materials for nanotechnology applications.

  10. Tactile friction of topical formulations.

    Science.gov (United States)

    Skedung, L; Buraczewska-Norin, I; Dawood, N; Rutland, M W; Ringstad, L

    2016-02-01

    The tactile perception is essential for all types of topical formulations (cosmetic, pharmaceutical, medical device) and the possibility to predict the sensorial response by using instrumental methods instead of sensory testing would save time and cost at an early stage product development. Here, we report on an instrumental evaluation method using tactile friction measurements to estimate perceptual attributes of topical formulations. Friction was measured between an index finger and an artificial skin substrate after application of formulations using a force sensor. Both model formulations of liquid crystalline phase structures with significantly different tactile properties, as well as commercial pharmaceutical moisturizing creams being more tactile-similar, were investigated. Friction coefficients were calculated as the ratio of the friction force to the applied load. The structures of the model formulations and phase transitions as a result of water evaporation were identified using optical microscopy. The friction device could distinguish friction coefficients between the phase structures, as well as the commercial creams after spreading and absorption into the substrate. In addition, phase transitions resulting in alterations in the feel of the formulations could be detected. A correlation was established between skin hydration and friction coefficient, where hydrated skin gave rise to higher friction. Also a link between skin smoothening and finger friction was established for the commercial moisturizing creams, although further investigations are needed to analyse this and correlations with other sensorial attributes in more detail. The present investigation shows that tactile friction measurements have potential as an alternative or complement in the evaluation of perception of topical formulations. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Fewer complications with bolt-connected than tunneled external ventricular drainage

    DEFF Research Database (Denmark)

    Slott Jensen, Torben; Carlsen, Jakob Gram; Sørensen, Jens Christian

    2016-01-01

    ) and complications including unintended removal, catheter obstruction, infection, CSF leakage, and mechanical problems. RESULTS: A total of 271 patients with 272 separate EVDs met the inclusion criteria. There was a statistically higher rate of complications leading to reinsertion in the tunneled EVD group (40...... %), compared to the bolt-connected EVD group (6.5 %). There was no significant difference in infection rates. CONCLUSIONS: Tunneled EVD has a relatively high frequency of complications leading to reinsertion. The use of Bolt-connected EVD technique can lower this frequency significantly. The number needed...... to treat is three for preventing a complication requiring reinsertion. Infection rates are low for both types of ventriculostomies. Accordingly, we recommend use of Bolt-connected EVDs in neurosurgical practice....

  12. Site ultrasonic measurement on RPV stud-bolt loading under hot transient of Qinshan NPP

    International Nuclear Information System (INIS)

    Qu Jiadi; Dou Yikang; Zhu Shiming

    1994-08-01

    It expounds that the key of solving thermal transient sealing problem is to obtain the thermal increment of stud-bolt loading. This loading, as a primary stress loading, is directly related to the bolt fatigue life and transient loading spectrum for vessel analysis. The fundamental works and main results of ultrasonic measurement on RPV stud-bolt loading on Qinshan site are also presented. The measuring capability has exceeded 1 m in length and temperature of 280 degree C, therefore, it is possible to be used in the field of NPP. The paper is the continuation of research work for sealing analysis and tests on the RPV (see SMiRT-9, 10)

  13. Failure analysis of single-bolted joint for lightweight composite laminates and metal plate

    Science.gov (United States)

    Li, Linjie; Qu, Junli; Liu, Xiangdong

    2018-01-01

    A three-dimensional progressive damage model was developed in ANSYS to predict the damage accumulation of single bolted joint in composite laminates under in-plane tensile loading. First, we describe the formulation and algorithm of this model. Second, we calculate the failure loads of the joint in fibre reinforced epoxy laminated composite plates and compare it with the experiment results, which validates that our model can appropriately simulate the ultimate tensile strength of the joints and the whole process of failure of structure. Finally, this model is applied to study the failure process of the light-weight composite material (USN125). The study also has a great potential to provide a strong basis for bolted joints design in composite Laminates as well as a simple tool for comparing different laminate geometries and bolt arrangements.

  14. Ultrasonic testing of core baffle former bolts of the core tanks of pressurised water reactors

    International Nuclear Information System (INIS)

    Bies, Christian M.; Alaerts, Louis; Bonitz, Frank W.; Devlin, Russell S.; Minogue, Patrick

    2013-01-01

    This article presents the MIDAS VI testing robot used by Westinghouse / WesDyne. This is a remotely operated underwater vehicle which positions ultrasonic probes under camera control. This vehicle makes it possible to substantially reduce the time required for setting up and preparing ultrasonic tests on core baffle former bolts. It has also accelerated the test procedure itself. Test methods have also been developed for bolt types which were hitherto considered incapable of being tested. One of these methods is based on a phased array probe. The article also reports on experiences gained over the course of years in testing core baffle former bolts in European nuclear power plants using the SUPREEM testing robot.

  15. Simulation and design of ECT differential bobbin probes for the inspection of cracks in bolts

    International Nuclear Information System (INIS)

    Ra, S W; Im, K H; Woo, Y D; Lee, S G; Kim, H J; Song, S J; Kim, S K; Cho, Y T; Jung, J A

    2015-01-01

    All Various defects could be generated in bolts for a use of oil filters for the manufacturing process and then may affect to the safety and quality in bolts. Also, fine defects may be imbedded in oil filter system during multiple forging manufacturing processes. So it is very important that such defects be investigated and screened during the multiple manufacturing processes. Therefore, in order effectively to evaluate the fine defects, the design parameters for bobbin-types were selected under a finite element method (FEM) simulations and Eddy current testing (ECT). Especially the FEM simulations were performed to make characterization in the crack detection of the bolts and the parameters such as number of turns of the coil, the coil size and applied frequency were calculated based on the simulation results. (paper)

  16. Special remote tooling developed and utilized to tighten TFTR TF coil casing bolts

    International Nuclear Information System (INIS)

    Burgess, T.W.; Walton, G.R.; Meighan, T.G.; Paul, B.L.

    1993-01-01

    Special tooling has been developed and used to tighten toroidal field (TF) coil casing bolts that have loosened from years of Tokamak Fusion Test Reactor (TFTR) operation. Due to their location, many of the TF casing bolts cannot be directly accessed or viewed; their condition was first discovered during unrelated inspections in 1988. Engineering solutions were, sought until 1992, when a remotely operated wrench concept was successfully demonstrated on a TF coil mockup. The concept was developed into several working tools that have successfully been applied to tighten several thousand TF casing bolts during recent scheduled outages. This effort has improved the integrity and reliability of the TF coil system in preparing for the final experimental phase of the TFTR. This paper discusses the design and application of this tooling

  17. Eliminating friction with friction: 2D Janssen effect in a friction-driven system.

    Science.gov (United States)

    Karim, M Yasinul; Corwin, Eric I

    2014-05-09

    The Janssen effect is a unique property of confined granular materials experiencing gravitational compaction in which the pressure at the bottom saturates with an increasing filling height due to frictional interactions with side walls. In this Letter, we replace gravitational compaction with frictional compaction. We study friction-compacted 2D granular materials confined within fixed boundaries on a horizontal conveyor belt. We find that even with high-friction side walls the Janssen effect completely vanishes. Our results demonstrate that gravity-compacted granular systems are inherently different from friction-compacted systems in at least one important way: vibrations induced by sliding friction with the driving surface relax away tangential forces on the walls. Remarkably, we find that the Janssen effect can be recovered by replacing the straight side walls with a sawtooth pattern. The mechanical force introduced by varying the sawtooth angle θ can be viewed as equivalent to a tunable friction force. By construction, this mechanical friction force cannot be relaxed away by vibrations in the system.

  18. Simulation and experiment for the inspection of stainless steel bolts in servicing using an ultrasonic phased array

    Science.gov (United States)

    Chen, Jinzhong; He, Renyang; Kang, Xiaowei; Yang, Xuyun

    2015-10-01

    The non-destructive testing of small-sized (M12-M20) stainless steel bolts in servicing is always a technical problem. This article focuses on the simulation and experimental research of stainless steel bolts with an artificial defect reflector using ultrasonic phased array inspection. Based on the observation of the sound field distribution of stainless steel bolts in ultrasonic phased array as well as simulation modelling and analysis of the phased array probes' detection effects with various defect sizes, different artificial defect reflectors of M16 stainless steel bolts are machined in reference to the simulation results. Next, those bolts are tested using a 10-wafer phased array probe with 5 MHz. The test results finally prove that ultrasonic phased array can detect 1-mm cracks in diameter with different depths of M16 stainless steel bolts and a metal loss of Φ1 mm of through-hole bolts, which provides technical support for future non-destructive testing of stainless steel bolts in servicing.

  19. Causes of Failure of High-Tensile Stud Bolts Used for Joining Metal Parts of Tower Crane

    Science.gov (United States)

    Tingaev, A. K.; Gubaydulin, R. G.; Shaburova, N. A.

    2017-11-01

    The causes of the failure of a high-tensile stud 2M48-6gx500 10.9 made from steel grade 30HGSA which led to a temporary inoperability of a tower crane were investigated. The bolts were used to assemble the tower sections and collapsed after 45 days from the moment the crane was commissioned. The cracks in the fracture are identified as fatigue with the characteristic sites of nucleation, sustainable development and static dolomite. To determine the possible causes of stud bolts destruction, metallographic, durometric and mechanical tests were carried out from which it follows that the stud bolt material in its original state corresponded to the delivery conditions. The destruction of the stud bolt appears to have resulted from a combination of several unfavorable factors: uncertainty about the actual tension of the stud bolt due to the lack of information about the magnitude of the twist factor; partial displacement of the centers of the brackets holes and rotation of the stud bolt axis during the sections’ assembly; no tight contact on the support surfaces of the section brackets. All this led to a discrepancy between the actual design of the stud bolt, the appearance of additional forces and the destruction of the stud bolt.

  20. The influence of target object shape on maximum grip aperture in human grasping movements

    NARCIS (Netherlands)

    Verheij, R.; Brenner, E.; Smeets, J.B.J.

    2014-01-01

    The shape of a target object could influence maximum grip aperture in human grasping movements in several different ways. Maximum grip aperture could be influenced by the required precision of digit placement, by the aim to avoid colliding with the wrong parts of the target objects, by the mass of

  1. Is grip strength a predictor for total muscle strength in healthy children, adolescents, and young adults?

    NARCIS (Netherlands)

    Wind, Anne E.; Takken, Tim; Helders, Paul J. M.; Engelbert, Raoul H. H.

    2010-01-01

    The primary purpose of this study was to examine whether grip strength is related to total muscle strength in children, adolescents, and young adults. The second purpose was to provide reference charts for grip strength, which could be used in the clinical and research setting. This cross-sectional

  2. Visual size cues in the programming of manipulative forces during precision grip.

    Science.gov (United States)

    Gordon, A M; Forssberg, H; Johansson, R S; Westling, G

    1991-01-01

    A size-weight illusion was used to examine the role of visual cues in the programming of manipulative forces during the lifting of test objects utilizing the precision grip. Three different boxes of equal weight and unequal size were lifted. These were equipped with an instrumented grip handle to measure the employed grip force, load force (vertical lifting force), force rates and vertical movement. All fifteen subjects participating in the study reported that the smallest box was the heaviest, which is consistent with size-weight illusion predictions. However, the rate of increase of the isometric grip and load forces initially during the lift, the peaks of the grip and load force and the vertical acceleration were all found to increase with the box size. Thus, despite the conscious perception indicating a heavier weight for the small object, the motor program was scaled for a lighter weight. Yet, no differences were found in grip force during the static phase of the lift, where weight related information was apparently available via sensory feedback. Previous studies have reported that the programming of the precision grip is based on somatosensory information gained during previous lifts (Johansson and Westling 1984, 1988a, b). The present study suggests that visual cues are integrated in the programming of manipulative forces during precision grip.

  3. Impairments in precision grip correlate with functional measures in adult hemiplegia.

    Science.gov (United States)

    McDonnell, Michelle N; Hillier, Susan L; Ridding, Michael C; Miles, Timothy S

    2006-07-01

    Analysis of a precision grip-lift task provides measures to assess functional disability of the hand, but the correlation between these measures and accepted tests of motor function in stroke patients has not been established. Seventeen subacute stroke patients were studied to compare parameters of a precision grip-lift task between the affected and unaffected side, and to correlate them with function. Functional impairment was assessed with the Action Research Arm Test and the Fugl-Meyer assessment, as well as grip strength and maximal finger-tapping speed. The grip force (GF) and load force (LF) were recorded as patients lifted a custom-built manipulandum. All measures were recorded on two separate occasions, at least 1 week apart. There was good reproducibility between testing sessions for the grip-lift and functional measures. The affected hand gripped the manipulandum for longer prior to lift-off than the unaffected hand, and the normal close temporal coupling between the rate of change of GF and LF during the lift was disrupted. These two measures correlated more highly with the ARAT than the FMA and, when combined with measures of grip strength and tapping speed, explained 71% of the variance of the ARAT. The grip-lift task is a sensitive measure of impaired dexterity following stroke and provides measures which correlate well with a commonly applied functional assessment scale. This task may be used clinically to detect changes in the hemiplegic upper limb during rehabilitation and recovery.

  4. Lamb Wave-Based Structural Health Monitoring on Composite Bolted Joints under Tensile Load

    Directory of Open Access Journals (Sweden)

    Bin Yang

    2017-06-01

    Full Text Available Online and offline monitoring of composite bolted joints under tensile load were investigated using piezoelectric transducers. The relationships between Lamb wave signals, pre-tightening force, the applied tensile load, as well as the failure modes were investigated. Results indicated that S0/A0 wave amplitudes decrease with the increasing of load. Relationships between damage features and S0/A0 mode were built based on the finite element (FE simulation and experimental results. The possibility of application of Lamb wave-based structure health monitoring in bolted joint-like composite structures was thus achieved.

  5. Failure analysis of bolted joints in foam-core sandwich composites

    DEFF Research Database (Denmark)

    Zabihpoor, M.; Moslemian, Ramin; Afshin, M.

    2008-01-01

    This study represents an effort to predict the bearing strength, failure modes, and failure load of bolted joints in foam-core sandwich composites. The studied joints have been used in a light full composite airplane. By using solid laminates, a new design for the joint zone is developed. These s......This study represents an effort to predict the bearing strength, failure modes, and failure load of bolted joints in foam-core sandwich composites. The studied joints have been used in a light full composite airplane. By using solid laminates, a new design for the joint zone is developed...

  6. Usage of prestressed vertical bolts for retrofitting flat slabs damaged due to punching shear

    Directory of Open Access Journals (Sweden)

    Hamed S. Askar

    2015-09-01

    An experimental investigation with the objective of retrofitting flat slabs damaged due to punching shear using prestressed vertical bolts is presented in this paper. The parameters examined in this study are vertical prestressed bolts with different ratios within the slab thickness, slab thickness and central column size. Through the experimental tests the load carrying capacity, deformation characteristics and the cracking behavior have been investigated. A comparison between the behavior of retrofitted slabs and their references showed that the proposed system of repair is effective and could be used in practice. A comparison between the experimental results and calculated punching failure load based on the formulas adopted by different codes, showed a reasonable agreement.

  7. Lamb Wave-Based Structural Health Monitoring on Composite Bolted Joints under Tensile Load

    Science.gov (United States)

    Yang, Bin; Xuan, Fu-Zhen; Xiang, Yanxun; Li, Dan; Zhu, Wujun; Tang, Xiaojun; Xu, Jichao; Yang, Kang; Luo, Chengqiang

    2017-01-01

    Online and offline monitoring of composite bolted joints under tensile load were investigated using piezoelectric transducers. The relationships between Lamb wave signals, pre-tightening force, the applied tensile load, as well as the failure modes were investigated. Results indicated that S0/A0 wave amplitudes decrease with the increasing of load. Relationships between damage features and S0/A0 mode were built based on the finite element (FE) simulation and experimental results. The possibility of application of Lamb wave-based structure health monitoring in bolted joint-like composite structures was thus achieved. PMID:28773014

  8. Impact extractive fracture of jointed steel plates of a bolted joint

    OpenAIRE

    Ambarita H.; Fujiki H.; Daimaruya M.

    2012-01-01

    This study is concerned with the development of a fracture criterion for the impact fracture of jointed steel plates of a bolted joint used in a car body. For the accurate prediction of crash characteristics of car bodies by computer-aided engineering (CAE), it is also necessary to examine the behavior and fracture of jointed steel plates subjected to impact loads. Although the actual impact fracture of jointed steel plates of a bolted joint used in cars is complicated, for simplifying the pr...

  9. Frictional performance of ball screw

    International Nuclear Information System (INIS)

    Nakashima, Katuhiro; Takafuji, Kazuki

    1985-01-01

    As feed screws, ball screws have become to be adopted in place of trapezoidal threads. The structure of ball screws is complex, but those are the indispensable component of NC machine tools and machining centers, and are frequently used for industrial robots. As the problems in the operation of ball screws, there are damage, life and the performance related to friction. As to the damage and life, though there is the problem of the load distribution on balls, the results of the research on rolling bearings are applied. The friction of ball screws consists of the friction of balls and a spiral groove, the friction of a ball and a ball, the friction in a ball-circulating mechanism and the viscous friction of lubricating oil. It was decided to synthetically examine the frictional performance of ball screws, such as driving torque, the variation of driving torque, efficiency, the formation of oil film and so on, under the working condition of wide range, using the screws with different accuracy and the nuts of various circuit number. The experimental setup and the processing of the experimental data, the driving performance of ball screws and so on are reported. (Kako, I.)

  10. Friction and anchorage loading revisited.

    Science.gov (United States)

    Dholakia, Kartik D

    2012-01-01

    Contemporary concepts of sliding mechanics explain that friction is inevitable. To overcome this frictional resistance, excess force is required to retract the tooth along the archwire (ie, individual retraction of canines, en masse retraction of anterior teeth), in addition to the amount of force required for tooth movement. The anterior tooth retraction force, in addition to excess force (to overcome friction), produces reciprocal protraction force on molars, thereby leading to increased anchorage loading. However, this traditional concept was challenged in recent literature, which was based on the finite element model, but did not bear correlation to the clinical scenario. This article will reinforce the fact that clinically, friction increases anchorage loading in all three planes of space, considering the fact that tooth movement is a quasistatic process rather than a purely continuous or static one, and that conventional ways of determining the effects of static or dynamic friction on anchorage load cannot be applied to clinical situations (which consist of anatomical resistance units and a complex muscular force system). The article does not aim to quantify friction and its effect on the amount of anchorage load. Rather, a new perspective regarding the role of various additional factors (which is not explained by contemporary concept) that may influence friction and anchorage loading is provided..

  11. Fuel assembly gripping device using self-locking mechanism

    International Nuclear Information System (INIS)

    Lee, G. M.; Choi, S.; Kim, K. S.; Kim, T. W.; Jeong, K. H.; Park, K. B.; Chang, M. H.

    1999-07-01

    This report presents an actuating principles and structure for two kind of the fuel assembly gripping devices (Gripper-A, B) developed for SMART. The main components of these grippers are push bundle, rotation bundle, upper guide tube and chuck assembly. The rope attached to winch system on moving cask hangs gripper's push bundle. Due to a down-and-up operation of winch system, the push bundle pushes crown teeth shaped rotation bundle and then it is pushed down and rotated counter clockwise. The push-and-pull sequential operation of push bundle makes the rotation bundle is pushed, rotated and returned, moreover it makes the chuck assembly is expanded or shrunk. The expansion and shrinkage motion of chuck assembly makes the gripper latch and release the fuel assembly. Gripper-A suits for the handling of the fuel assembly with square shaped latching hole. Otherwise Gripper-B suits for a circular shaped latching hole. (author). 5 refs., 20 figs

  12. The laboratory station for tyres grip testing on different surfaces

    Science.gov (United States)

    Kalinowski, K.; Grabowik, C.; Janik, W.; Ćwikła, G.; Skowera, M.

    2015-11-01

    The paper presents the conception of the device for tyre grip testing in the laboratory conditions. The main purpose is to provide a device working in confined spaces, which enables rapid changes of the tested samples of the road surfaces. Among the key assumptions the minimization of the device dimensions and the relative ease of transportation and mobility - the ability to quick assemble and disassemble were also assumed. The main components of the projected workstation includes: the replaceable platform for mounting samples of a road surface, the roller conveyor, the drive of the platform, the wheel mounting assembly and the axial force measuring system. At the design the station a morphological structure method has been used, particular elements have been optimized individually.

  13. NBL Pistol Grip Tool for Underwater Training of Astronauts

    Science.gov (United States)

    Liszka, Michael; Ashmore, Matthew; Behnke, Mark; Smith, Walter; Waterman, Tod

    2011-01-01

    A document discusses a lightweight, functional mockup of the Pistol Grip Tool for use during underwater astronaut training. Previous training tools have caused shoulder injuries. This new version is more than 50 percent lighter [in water, weight is 2.4 lb (=1.1 kg)], and can operate for a six-hour training session after 30 minutes of prep for submersion. Innovations in the design include the use of lightweight materials (aluminum and Delrin(Registered TradeMark)), creating a thinner housing, and the optimization of internal space with the removal of as much excess material as possible. This reduces tool weight and maximizes buoyancy. Another innovation for this tool is the application of a vacuum that seats the Orings in place and has shown to be reliable in allowing underwater usage for up to six hours.

  14. Combined In-Plane and Through-the-Thickness Analysis for Failure Prediction of Bolted Composite Joints

    Science.gov (United States)

    Kradinov, V.; Madenci, E.; Ambur, D. R.

    2004-01-01

    Although two-dimensional methods provide accurate predictions of contact stresses and bolt load distribution in bolted composite joints with multiple bolts, they fail to capture the effect of thickness on the strength prediction. Typically, the plies close to the interface of laminates are expected to be the most highly loaded, due to bolt deformation, and they are usually the first to fail. This study presents an analysis method to account for the variation of stresses in the thickness direction by augmenting a two-dimensional analysis with a one-dimensional through the thickness analysis. The two-dimensional in-plane solution method based on the combined complex potential and variational formulation satisfies the equilibrium equations exactly, and satisfies the boundary conditions and constraints by minimizing the total potential. Under general loading conditions, this method addresses multiple bolt configurations without requiring symmetry conditions while accounting for the contact phenomenon and the interaction among the bolts explicitly. The through-the-thickness analysis is based on the model utilizing a beam on an elastic foundation. The bolt, represented as a short beam while accounting for bending and shear deformations, rests on springs, where the spring coefficients represent the resistance of the composite laminate to bolt deformation. The combined in-plane and through-the-thickness analysis produces the bolt/hole displacement in the thickness direction, as well as the stress state in each ply. The initial ply failure predicted by applying the average stress criterion is followed by a simple progressive failure. Application of the model is demonstrated by considering single- and double-lap joints of metal plates bolted to composite laminates.

  15. Comparative study of maximum isometric grip strength in different sports

    Directory of Open Access Journals (Sweden)

    Noé Gomes Borges Junior

    2009-01-01

    Full Text Available http://dx.doi.org/10.5007/1980-0037.2009v11n3p292   The objective of this study was to compare maximum isometric grip strength (Fmaxbetween different sports and between the dominant (FmaxD and non-dominant (FmaxND hand. Twenty-nine male aikido (AI, jiujitsu (JJ, judo (JU and rowing (RO athletes and 21non-athletes (NA participated in the study. The hand strength test consisted of maintainingmaximum isometric grip strength for 10 seconds using a hand dynamometer. The position of the subjects was that suggested by the American Society of Hand Therapy. Factorial 2X5 ANOVA with Bonferroni correction, followed by a paired t test and Tukey test, was used for statistical analysis. The highest Fmax values were observed for the JJ group when using the dominant hand,followed by the JU, RO, AI and NA groups. Variation in Fmax could be attributed to handdominance (30.9%, sports modality (39.9% and the interaction between hand dominance andsport (21.3%. The present results demonstrated significant differences in Fmax between the JJ and AI groups and between the JJ and NA groups for both the dominant and non-dominant hand. Significant differences in Fmax between the dominant and non-dominant hand were only observed in the AI and NA groups. The results indicate that Fmax can be used for comparisonbetween different sports modalities, and to identify differences between the dominant and nondominanthand. Studies involving a larger number of subjects will permit the identification of differences between other modalities.

  16. Labor Supply and Optimization Frictions

    DEFF Research Database (Denmark)

    Søgaard, Jakob Egholt

    In this paper I investigate the nature of optimization frictions by studying the labor market of Danish students. This particular labor market is an interesting case study as it features a range of special institutional settings that affect students’ incentive to earn income and comparing outcomes...... across these setting effectively allow you to distinguish between different types of frictions. I find that the considered labor market is significantly affected by optimizations frictions, which masks the bunching at kink points normally associated with a positive labor supply elasticity under standard...

  17. Frictional properties of confined polymers

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, Vladimir N; Persson, Bo N J

    2008-01-01

    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: a) polymer sliding against a hard substrate, and b) polymer sliding on polymer. In the first setup the shear stresses are relatively...... independent of molecular length. For polymer sliding on polymer the friction is significantly larger, and dependent on the molecular chain length. In both cases, the shear stresses are proportional to the squeezing pressure and finite at zero load, indicating an adhesional contribution to the friction force...

  18. REDUCED ENGINE FRICTION AND WEAR

    Energy Technology Data Exchange (ETDEWEB)

    Ron Matthews

    2005-05-01

    This Final Technical Report discusses the progress was made on the experimental and numerical tasks over the duration of this project regarding a new technique for decreasing engine friction and wear via liner rotation. The experimental subtasks involved quantifying the reduction in engine friction for a prototype rotating liner engine relative to a comparable baseline engine. Both engine were single cylinder conversions of nominally identical production four-cylinder engines. Hot motoring tests were conducted initially and revealed that liner rotation decreased engine friction by 20% under motoring conditions. A well-established model was used to estimate that liner rotation should decrease the friction of a four-cylinder engine by 40% under hot motoring conditions. Hot motoring tear-down tests revealed that the crankshaft and valve train frictional losses were essentially the same for the two engines, as expected. However, the rotating liner engine had much lower (>70%) piston assembly friction compared to the conventional engine. Finally, we used the Instantaneous IMEP method to compare the crank-angle resolved piston assembly friction for the two engines. Under hot motoring conditions, these measurements revealed a significant reduction in piston assembly friction, especially in the vicinity of compression TDC when the lubrication regime transitions from hydrodynamic through mixed and into boundary friction. We have some remaining problems with these measurements that we expect to solve during the next few weeks. We will then perform these measurements under firing conditions. We also proposed to improve the state-of-the-art of numerical modeling of piston assembly friction for conventional engines and then to extend this model to rotating liner engines. Our research team first modeled a single ring in the Purdue ring-liner test rig. Our model showed good agreement with the test rig data for a range of speeds and loads. We then modeled a complete piston

  19. Effect of the Grip Angle on Off-Spin Bowling Performance Parameters, Analysed with a Smart Cricket Ball

    OpenAIRE

    Franz Konstantin Fuss; Batdelger Doljin; René E. D. Ferdinands

    2018-01-01

    In the off-spin bowling grip, the ball is clamped between index and middle fingers. Spin bowlers attempt to select a spread angle between these two fingers that achieves comfort and optimises performance. The aim of this paper was to investigate whether the standard grip is superior to narrow and wide grips. The bowling performance parameters were obtained from a smart cricket ball. Smart ball data revealed that the performance parameters varied with grip type. The following parameters were o...

  20. Showing Area Matters: A Work of Friction

    Science.gov (United States)

    Van Domelen, David

    2010-01-01

    Typically, we teach the simplified friction equation of the form F[subscript s] = [mu][subscript s]N for static friction, where F[subscript s] is the maximum static friction, [mu][subscript s] is the coefficient of static friction, and "N" is the normal force pressing the surfaces together. However, this is a bit too simplified, and…

  1. A Pedagogical Model of Static Friction

    OpenAIRE

    Pickett, Galen T.

    2015-01-01

    While dry Coulombic friction is an elementary topic in any standard introductory course in mechanics, the critical distinction between the kinetic and static friction forces is something that is both hard to teach and to learn. In this paper, I describe a geometric model of static friction that may help introductory students to both understand and apply the Coulomb static friction approximation.

  2. A simplified design of clamping system and fixtures for friction stir welding of aluminium alloys

    Directory of Open Access Journals (Sweden)

    Mohammed. M. Hasan

    2015-12-01

    Full Text Available Sound friction stir welds could be attained by using an active design of backing/clamping system with a proper selection of the welding parameters. This work presented a simplified design of fixtures and backing plates to be used for friction stir welding of aluminum alloys. The test-rig was constructed to prevent dispersal or lifting of the specimens throughout the joining process and to ensure uniform distribution of temperature along the plates. The workpieces were subjected to uniform lateral and vertical pressures by means of bolts and nuts. Compound backing plates and pressure bars with additional side plates were included to increase the heat sink. Several coupons of dissimilar aluminum alloys AA7075 and AA6061 were joined to inspect the validity of this design. The tests showed promising results with defects-free welds, good strength and smooth surface finish without geometric imperfection and gap creation between the welded specimens. Efficiency of the joint reached its maximum value of about 82% with respect to the ultimate strength of the AA6061 alloy at 1100 rpm rotation speed and 300 mm/min feed. These results encourage using and improving the present design for future studies of friction stir welding.

  3. Friction Material Composites Materials Perspective

    CERN Document Server

    Sundarkrishnaa, K L

    2012-01-01

    Friction Material Composites is the first of the five volumes which strongly educates and updates engineers and other professionals in braking industries, research and test labs. It explains besides the formulation of design processes and its complete manufacturing input. This book gives an idea of mechanisms of friction and how to control them by designing .The book is  useful for designers  of automotive, rail and aero industries for designing the brake systems effectively with the integration of friction material composite design which is critical. It clearly  emphasizes the driving  safety and how serious designers should  select the design input. The significance of friction material component like brake pad or a liner as an integral part of the brake system of vehicles is explained. AFM pictures at nanolevel illustrate broadly the explanations given.

  4. Size scaling of static friction.

    Science.gov (United States)

    Braun, O M; Manini, Nicola; Tosatti, Erio

    2013-02-22

    Sliding friction across a thin soft lubricant film typically occurs by stick slip, the lubricant fully solidifying at stick, yielding and flowing at slip. The static friction force per unit area preceding slip is known from molecular dynamics (MD) simulations to decrease with increasing contact area. That makes the large-size fate of stick slip unclear and unknown; its possible vanishing is important as it would herald smooth sliding with a dramatic drop of kinetic friction at large size. Here we formulate a scaling law of the static friction force, which for a soft lubricant is predicted to decrease as f(m)+Δf/A(γ) for increasing contact area A, with γ>0. Our main finding is that the value of f(m), controlling the survival of stick slip at large size, can be evaluated by simulations of comparably small size. MD simulations of soft lubricant sliding are presented, which verify this theory.

  5. 77 FR 32698 - Proposed Extension of Existing Information Collection; Safety Standards for Roof Bolts in Metal...

    Science.gov (United States)

    2012-06-01

    ... provided in the desired format, reporting burden (time and financial resources) is minimized, collection... Extension of Existing Information Collection; Safety Standards for Roof Bolts in Metal and Nonmetal Mines... agencies with an opportunity to comment on proposed and continuing collections of information in accordance...

  6. Global Fatigue Life Modelling of Steel Half-pipes Bolted Connections

    NARCIS (Netherlands)

    Jovašević, S.; Correia, J. A F O; Pavlovic, M.; Rebelo, C.; De Jesus, A. M P; Veljkovic, M.; Simoes da Silva, L

    2016-01-01

    A steel hybrid structural solution for onshore wind turbine towers was proposed in the European project SHOWTIME. This solution is used in the lattice structure for the lower portion of the tower. Recently, a procedure for fatigue life estimation of steel half-pipes bolted connections applied in

  7. [Effects of temperature-shifted controlling on bolting and flowering of endive].

    Science.gov (United States)

    He, Zhong-qun; Wang, Jun

    2015-05-01

    Temperature sensitive periods and growth characteristics of endive under different temperatures were investigated in greenhouse by weekly reciprocal transferring experiment condition between warm (17 °C) and cold (average 10.5 °C) environment. The results indicated that difference in growth rate of endive was significant in cold and warm environments. There was no temperature sensitive period in endive, and it could feel outside temperature, thus, conducted vernalization induction in setting temperature range (2-17 °C). Meanwhile, low temperature favored the flower bud differentiation. Endives all completed flower bud differentiation and bloting either in warm or in cold environment. It took 24 days to complete flower bud differentiation in cold environment and 60 days in warm environment, and bolting was 7 days later in warm environment than in cold environment. From seeding to bolting, it took 111 days in warm environment and 104 days in cold environment, respectively. After flowering induction, the seeding bolting rate from warm environment to cold environment was obviously higher than that from cold to warm environment and higher temperature led to faster bolting in this period.

  8. Monitoring bolt tightness of rail joints using axle box acceleration measurements

    NARCIS (Netherlands)

    Oregui Echeverria-Berreyarza, M.; Li, S.; Li, Z.; Carroll, R; Dollevoet, R.P.B.J.

    2016-01-01

    Rail joints are a weak component in railway tracks because of the large impact and wheel-rail contact forces. Every train passage contributes to the deterioration of rail joints, causing visible (e.g. battered rails) and invisible (e.g. loose bolts) damages. The invisible damage cannot be detected

  9. BWR containment vessel drywell head bolt de-tensioning during noble metal chemical application

    International Nuclear Information System (INIS)

    Herrera, M.; Mattson, R.

    2001-01-01

    Implementation of Noble Metal Chemical Application (NMCA) in a Boiling Water Reactor (BWR) requires injection of a noble metal compound while the reactor is idle at hot shutdown conditions. In order to minimize outage time, utilities are very pro-actively finding ways to reduce the number of critical path tasks. One of these tasks is to remove some containment vessel drywell head bolts during the NMCA idle time. This, thereby, saves the utilities outage time, or they can perform other tasks as desired. Using design basis conditions and state-of-the-art analytical techniques, detailed finite element stress analyses of the closure region are performed. Two acceptance criteria are evaluated. The first is that contained within Section III of the ASME Code for allowable stresses. The second relates to leak tightness, i.e., with bolt removal the joint must still remain leak tight. This paper describes the activities performed to justify bolt removal during the noble metal compound injection idle time at a particular plant. Drywell joint integrity criteria, design input, and assumptions are defined, and analytical results justifying bolt removal are presented. (author)

  10. Residual Strength of Glued-in Bolts After 9 Years In Situ Loading

    DEFF Research Database (Denmark)

    Pedersen, Martin Bo Uhre; Clorius, Christian Odin; Damkilde, Lars

    1996-01-01

    deviation of 37 kN. Comparing this mean residual strength with previously recorded test data reveals a 5% strength reduction. The force displacement curves shows no plastic capacity in the connections. At fracture, a displacement between 0.4 mm and 1.0 mm was observed. In the majority of failures the bolts...

  11. Long term ground support with stainless steel and nickel alloy rock bolts

    International Nuclear Information System (INIS)

    Shaffer, T.F.; Revie, R.W.; Mandal, A.

    1994-01-01

    Stainless steel and nickel alloy Swellex rock bolts have been developed to provide long-term ground support in corrosive environments or in underground openings that are inaccessible for periodic reconditioning. Laboratory and underground testing has shown that the mechanical properties of stainless steel Swellex rock bolts am adequate for long term service. The corrosivity of underground sites may vary considerably and no one grade of stainless steel will provide adequate corrosion resistance economically for permanent service at all sites. Six stainless steels and two nickel alloys have been evaluated and used to manufacture Swellex. These alloys can be used to manufacture all types of rock bolts including mechanically anchored bolts. The selection of the lowest-cost corrosion-resistant alloy suitable for the lifetime objective at a given site may be problematic. Therefore, a mine corrosivity assessment procedure, in which the performance of several candidate materials for permanent service at a specific site can be determined quickly and economically, is being developed and will be available in 1995

  12. The baffle-barrel-bolting analysis program: evolution and technical accomplishments

    International Nuclear Information System (INIS)

    Schwirian, R.E.; Forsyth, D.R.; Snyder, M.D.; Bhandari, D.R.; Barsic, J.A.; Rabenstein, W.D.

    2001-01-01

    In Westinghouse pressurized water reactors (PWR) the reactor core is surrounded by baffle plates, which provide lateral restraint for the fuel assemblies at the core boundary. Baffle plates are attached to horizontal supports called former plates by baffle-former bolts. The formers are attached to the core barrel which also provides vertical support for the core. The B3 analysis program addresses the possibility of reduced baffle-former bolting in Westinghouse U.S. domestic plant designs with respect to the relevant design criteria. Since safety is the overriding motivation for the program, faulted events have received the most in-depth attention. This focus has been reinforced by the fact that the loads produced by the loss-of-coolant-accident (LOCA) have usually been the most limiting of all those considered. Consequently, much of the presentation below deals with the development of analysis techniques and acceptance criteria to demonstrate that LOCA-induced loads on the bolts and the fuel assemblies will be acceptable with significantly reduced baffle-former bolting. A discussion of the other faulted, normal, and upset analyses performed as part of the program will also be presented. (author)

  13. Professor Usain Bolt Welcomes You to the Schoolyard: Physics for Champions

    Science.gov (United States)

    Vourlias, Kostas; Seroglou, Fanny

    2016-01-01

    Could Usain Bolt achieve what teachers often fail to do? Could this famous Olympic winner challenge and motivate students to study mechanics and introduce them to the principles of physics in a fun way, outside of the classroom? In order to answer these questions, we "invited" for one semester the world record holder to visit our Greek…

  14. Seismic Properties of Moment-resisting Timber Joints with a Combination of Bolts and Nails

    Directory of Open Access Journals (Sweden)

    Awaludin A.

    2011-01-01

    Full Text Available Improvement of cyclic or dynamic performance of timber connections has been intensively conducted since the overall response of wooden structures is merely a function of joint performance. For a bolted joint, filling the lead-hole clearance with epoxy resin or gluing high embedding-strength materials at the interface of the individual timber member are probably the most common methods. This study presents cyclic test results of moment-resisting joints with a combination of bolts and nails. The nails were placed closer to the joint centroid than the bolts, acting as additional fasteners and were expected to improve the seismic performance of the joints. Static-cyclic test results confirmed the increase of joint stiffness and moment resistance due to the additional nails. The nails contribute to the increase of hysteretic damping significantly though pinching behavior or narrowing the hysteresis loops close to zero rotation points was still observed. The results indicated that contribution of nails or bolts on moment resistance and hysteretic damping can be superimposed.

  15. Mechanical tests of the bolt of the gripper latch on the control rod cluster

    International Nuclear Information System (INIS)

    Lemaire, E.; Couet, D.; Molinie, D.; Grandjean, Y.; Radat, M.P.; Guttmann, D.

    1998-01-01

    Failure analysis and mechanical testing indicate that control rod drive mechanisms malfunctioning by 1995-96 is due to rupture by fatigue of a bolt inside the stationary gripper assembly. Fatigue is enhanced by free working following surface adaptation and unscrewing of the assembly. These results are taken into account for the choice of a new anti-rotation device. (authors)

  16. KINEMATICS FRICTION PAIR FOR EXAMPLE NEEDLE BEARINGS

    OpenAIRE

    Jerzy NACHIMOWICZ; Robert KORBUT

    2014-01-01

    The present study concerns certain phenomena that take place in the needle roller bearing. The friction that generates the anti-torque of a friction pair is the major factor that influences the needle bearing’s wear. In the needle bearing there occur two predominant types of friction: the rolling friction and the sliding friction, and both are subject to examination. The study presents recordings and analysis of the movements of all needle bearing’s rolling elements. The examination was carri...

  17. Effects of kinesio tape compared with non-elastic tape on hand grip strength.

    Science.gov (United States)

    Kim, Ji Young; Kim, Seong Yeol

    2016-05-01

    [Purpose] Many assumptions have been made about taping and several studies have considered tape application methods; however, the true effect of taping on muscle strength remains unclear. Most previous studies compared application techniques using Kinesio tape (KT), but studies that compared muscle strength using non-elastic tape (NT) are limited. Moreover, no studies have applied KT and NT in the same way to assess grip strength in normal subjects. The purpose of this study was to evaluate the immediate effect of application of two tapes with different elastic properties on maximal grip strength in healthy adults. [Subjects and Methods] Twenty healthy adults were divided into two groups (KT and NT). Maximal grip strength was measured with a dynamometer. Forearm extensor muscles of the dominant hand were then taped and subjects were immediately asked to perform hand grip movement with maximum strength in the same standardized manner. [Results] In the KT group, maximal grip strength was significantly increased compared to the initial value; however, in the NT group, there was no significant difference in maximal grip strength. [Conclusion] This study suggests that only Kinesio tape can increase maximal grip strength immediately after application on the extensor region of the forearm.

  18. How dependent are grip force and arm actions during holding an object?

    Science.gov (United States)

    Danion, F

    2004-09-01

    In everyday life, when manipulating objects, arm actions and precision grip force are tightly coupled by the central nervous system. To investigate the extent of this neural coupling, 11 subjects were asked to perform tasks that encourage either the coupling (Task 1) or the dissociation (Task 2 and 3) of grip force and arm actions. During Task 1, subjects held a grasping device, with an extra load suspended underneath by a string. Then, using the other hand, subjects were asked to lift or release the suspended load, while maintaining unaffected the posture of the grasping arm. During Task 2, while holding the device, subjects received similar instructions, but this time the extra load was suspended underneath the forearm. During Task 3, subjects were explicitly asked to modulate their grip force without moving the arm. In Task 1, grip force changed in parallel with, or slightly ahead of, changes in load, which is consistent with the view of a feedforward mechanism making grip force largely subordinate to ongoing arm actions. In Task 2, even though subjects had no obvious reasons to modulate their force (i.e. the load of the device was constant) they did so, with a number of features that resemble performance in Task 1. In Task 3, as expected, voluntary modulations in grip force had no effect on arm actions. It is concluded that the neural coupling between arm actions and grip force (1) can possibly lead to clumsy reactions, (2) depends on the focal action, and (3) is only unidirectional.

  19. The evaluation of skin friction using a frictional feel analyzer.

    Science.gov (United States)

    Egawa, Mariko; Oguri, Motoki; Hirao, Tetsuji; Takahashi, Motoji; Miyakawa, Michio

    2002-02-01

    Sensory evaluation is an important factor for cosmetic products. Several devices for the measurement of sensory properties have been developed in recent years. The objective here is to measure skin surface friction using these devices and examine the correlation with other physiological parameters in order to evaluate the potential of physical measurement of tactile sensation. A KES-SE Frictional Analyzer, a commercial device for measurement of surface frictional characteristics, was used in this study. An arm holder was added to this device for measurement on the human forearm. The frictional coefficient (MIU) and its mean deviation (MMD) were used as the parameter to indicate surface friction. The moisture content in the stratum corneum was measured with a Corneometer CM825, the transepidermal water loss with a Tewameter TM210, the viscoelastic properties of the skin with a Cutometer SEM575 and the skin surface pattern by observing the negative replica using silicon rubber. The MIU was not influenced by load; however, it was increased due to water application on the skin. The relationship between MIU and the moisture content in the stratum comeum, between MMD and skin surface pattern and between MMD and viscosity of both normal human forearm skin and SDS (sodium dodecyl sulfate)-induced dry skin were confirmed by statistical analysis in a test on human subjects. There was also a correlation between either MIU or MMD and sensory evaluation in the morning after the application of moisturizing products. Human skin surface friction was measured by using a KES-SE Frictional Analyzer. Judging from the correlation between either MIU or MMD and sensory evaluation, we considered this instrumental analysis to be useful for evaluating the tactile impression of human skin.

  20. Outcomes of single-stage grip-release reconstruction in tetraplegia.

    Science.gov (United States)

    Reinholdt, Carina; Fridén, Jan

    2013-06-01

    To evaluate the outcomes of our technique for single-stage grip-release reconstruction and compare it with previous 1- and 2-stage grip reconstructions in tetraplegia. A total of 14 patients (16 hands) with tetraplegia underwent a single-stage combination of operations to provide pinch, grip, and release function. We compared the study group with a historical control group of 15 patients (18 hands) who had been treated with staged flexion-extension grip-release reconstructions. Both groups were classified as ocular cutaneous 4. Assessment parameters included grip and pinch strength, maximal opening of the first webspace, and Canadian Occupational Performance Measurement. Both groups were rehabilitated with early active mobilization beginning the first day after surgery. Grip strength and opening of the first webspace were significantly greater in the single-stage group than in the comparative group. Pinch strength was not significantly different between groups. On the Canadian Occupational Performance Measurement score, patients belonging to the single-stage group were highly satisfied (increase of 3.7 points) and could perform several of their self-selected goals (3.5 points of improvement). The single-stage grip-release reconstruction provides people who have spinal cord injuries and tetraplegia with improved and reliable grip function; active finger flexion, active thumb flexion, passive thumb extension, and passive interossei function can all be achieved through this procedure. Early active mobilization is particularly important in improving functional outcome after this combination of grip reconstruction procedures. Therapeutic III. Copyright © 2013 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  1. Immediate and Delayed Effects of Forearm Kinesio Taping on Grip Strength

    Science.gov (United States)

    Kouhzad Mohammadi, Hosein; Khademi Kalantari, Khosro; Naeimi, Sedighe Sadat; Pouretezad, Mohammad; Shokri, Esmaeil; Tafazoli, Mojdeh; Dastjerdi, Mahboobeh; Kardooni, Leila

    2014-01-01

    Background: Due to the fundamental role of gripping in most upper limb activities, grip strength promotion is a chief goal in the treatment of patients with upper limb musculoskeletal disorders. Kinesio taping is a novel and effective therapeutic technique believed to facilitate muscle contraction through stimulating mechanoreceptors and increasing the sensory feedback around the taped region. Objectives: The present study aimed to identify the best region (flexor, extensor and flexor/extensor regions) and time (immediate, 0.5, 1, 1.5, and 2 hours) of forearm Kinesio taping to obtain the maximum improvement in grip strength. Materials and Methods: In this longitudinal study, 40 healthy men and women (the mean age of 22.3 ± 2.19 years) were selected among students of Shahid Beheshti University of Medical Sciences, Tehran, Iran by simple, nonrandom sampling method. A dynamometer was used to measure grip strength immediately and every 30 minutes during the two hours after I-shaped application of tape (with 50% stretch) to the flexor, extensor, and flexor/extensor forearm muscles. Results: Grip strength was significantly increased in various muscle groups for males (P = 0.002) and females (P = 0.000) of the forearm and at different intervals for males (P = 0.000) and females (P = 0.000). Moreover, in both men and women, tape application to the extensor region provided greater grip strength compared to taping of the flexor and flexor/extensor regions (P = 0.000 for both). Furthermore, the maximum increase in grip strength were 0.5 (10.8% increase, P = 0.001) and 1.5 h (23.9% increase, P = 0.000) after taping in males and females, respectively. Conclusions: Taping the extensor region of forearm is recommended to achieve higher grip strength. Although grip strength increased at a slower pace in females than males, the final values were higher in women. PMID:25389492

  2. Immediate and delayed effects of forearm kinesio taping on grip strength.

    Science.gov (United States)

    Kouhzad Mohammadi, Hosein; Khademi Kalantari, Khosro; Naeimi, Sedighe Sadat; Pouretezad, Mohammad; Shokri, Esmaeil; Tafazoli, Mojdeh; Dastjerdi, Mahboobeh; Kardooni, Leila

    2014-08-01

    Due to the fundamental role of gripping in most upper limb activities, grip strength promotion is a chief goal in the treatment of patients with upper limb musculoskeletal disorders. Kinesio taping is a novel and effective therapeutic technique believed to facilitate muscle contraction through stimulating mechanoreceptors and increasing the sensory feedback around the taped region. The present study aimed to identify the best region (flexor, extensor and flexor/extensor regions) and time (immediate, 0.5, 1, 1.5, and 2 hours) of forearm Kinesio taping to obtain the maximum improvement in grip strength. In this longitudinal study, 40 healthy men and women (the mean age of 22.3 ± 2.19 years) were selected among students of Shahid Beheshti University of Medical Sciences, Tehran, Iran by simple, nonrandom sampling method. A dynamometer was used to measure grip strength immediately and every 30 minutes during the two hours after I-shaped application of tape (with 50% stretch) to the flexor, extensor, and flexor/extensor forearm muscles. Grip strength was significantly increased in various muscle groups for males (P = 0.002) and females (P = 0.000) of the forearm and at different intervals for males (P = 0.000) and females (P = 0.000). Moreover, in both men and women, tape application to the extensor region provided greater grip strength compared to taping of the flexor and flexor/extensor regions (P = 0.000 for both). Furthermore, the maximum increase in grip strength were 0.5 (10.8% increase, P = 0.001) and 1.5 h (23.9% increase, P = 0.000) after taping in males and females, respectively. Taping the extensor region of forearm is recommended to achieve higher grip strength. Although grip strength increased at a slower pace in females than males, the final values were higher in women.

  3. Contact acoustic nonlinearity (CAN)-based continuous monitoring of bolt loosening: Hybrid use of high-order harmonics and spectral sidebands

    Science.gov (United States)

    Zhang, Zhen; Liu, Menglong; Liao, Yaozhong; Su, Zhongqing; Xiao, Yi

    2018-03-01

    The significance of evaluating bolt tightness in engineering structures, preferably in a continuous manner, cannot be overemphasized. With hybrid use of high-order harmonics (HOH) and spectral sidebands, a contact acoustic nonlinearity (CAN)-based monitoring framework is developed for detecting bolt loosening and subsequently evaluating the residual torque on a loose bolt. Low-frequency pumping vibration is introduced into the bolted joint to produce a "breathing" effect at the joining interface that modulates the propagation characteristics of a high-frequency probing wave when it traverses the bolt, leading to the generation of HOH and vibro-acoustic nonlinear distortions (manifested as sidebands in the signal spectrum). To gain insight into the mechanism of CAN generation and to correlate the acquired nonlinear responses of a loose joint with the residual torque remaining on the bolt, an analytical model based on micro-contact theory is established. Two types of nonlinear index, respectively exploiting the induced HOH and spectral sidebands, are defined without dependence on excitation intensity and are experimentally demonstrated to be effective in continuously monitoring bolt loosening in both aluminum-aluminum and composite-composite bolted joints. Taking a step further, variation of the index pair is quantitatively associated with the residual torque on a loose bolt. The approach developed provides a reliable method of continuous evaluation of bolt tightness in both composite and metallic joints, regardless of their working conditions, from early awareness of bolt loosening at an embryonic stage to quantitative estimation of residual torque.

  4. A Smart Washer for Bolt Looseness Monitoring Based on Piezoelectric Active Sensing Method

    Directory of Open Access Journals (Sweden)

    Heyue Yin

    2016-10-01

    Full Text Available Piezoceramic based active sensing methods have been researched to monitor preload on bolt connections. However, there is a saturation problem involved with this type of method. The transmitted energy is sometimes saturated before the maximum preload which is due to it coming into contact with flat surfaces. When it comes to flat contact surfaces, the true contact area will easily saturate with the preload. The design of a new type of bolt looseness monitoring sensor, a smart washer, is to mitigate the saturation problem. The smart washer is composed of two annular disks with contact surfaces that are machined into convex and concave respectively, to eliminate the complete flat contact surfaces and to reduce the saturation effect. One piezoelectric patch is bonded on the non-contact surface of each annular disk. These two mating annular disks form a smart washer. One of the two piezoelectric patches serves as an actuator to generate an ultrasonic wave that propagates through the contact surface; the other one serves as a sensor to detect the propagated waves. The wave energy propagated through the contact surface is proportional to the true contact area which is determined by the bolt preload. The time reversal method is used to extract the peak of the focused signal as the index of the transmission wave energy; then, the relationship between the signal peak and bolt preload is obtained. Experimental results show that the focused signal peak value changes with the bolt preload and presents an approximate linear relationship when the saturation problem is experienced. The proposed smart washer can monitor the full range of the rated preload.

  5. Anticipatory grip force between 1 and 3g

    Science.gov (United States)

    White, Olivier; Van Loon, ing.. Jack J. W. A.; Thonnard, Jean-Louis; Hermsdorfer, Joachim; Lefevre, Philippe

    One remarkable capacity of utilizing common tools appropriately as soon as we grasp them relies on the ability to determine in advance the grip force (GF) required to handle them in relation to their mechanical properties and the surrounding environment. This anticipatory strategy avoids the uncompressible delays in the feedback system. The predictive control of GF is made possible because the nervous system can learn, store and then select the internal representations of the dynamics of innumerable objects, known as internal models. Beside this flexibility, the nervous system's ability to learn different task dynamics is often limited in classical robotic experiments The environment itself can be profoundly modified in altered gravity or centrifugation. The few studies that investigated motor adaptation in such contexts did not consider the interaction between gravitational phases and even less the transitions across environments. Here, we tested subject's abilities to adapt to levels of gravitational fields generated by a human centrifuge. In Experiment 1, seven subjects performed 4 lifting trials in each gravitational phase (1 to 2.5g and then 2.5 to 1g by steps of 0.5g) with a 0.12 kg instrumented object. In Experiment 2, six subjects performed vertical oscillations of the object during transitions between 1 and 3g (0.5g steps, ascending and descending phases, profile repeated twice). We continuously measured GF, load force (LF) and ambient gravity. We hypothesized that participants were able to predictively adjust GF to the new environment. In Experiment 1, participants adjusted their GF proportionally to gravity and decreased GF across trials within a given gravitational environment. Preload phases decreased over time from 300ms to 50ms irrespective of gravity. We quantified the abilities of participants to switch across environments by subtracting GF recorded in the last trial in the current gravity level from GF during the first trial in the new environment

  6. High speed friction microscopy and nanoscale friction coefficient mapping

    International Nuclear Information System (INIS)

    Bosse, James L; Lee, Sungjun; Huey, Bryan D; Andersen, Andreas Sø; Sutherland, Duncan S

    2014-01-01

    As mechanical devices in the nano/micro length scale are increasingly employed, it is crucial to understand nanoscale friction and wear especially at technically relevant sliding velocities. Accordingly, a novel technique has been developed for friction coefficient mapping (FCM), leveraging recent advances in high speed AFM. The technique efficiently acquires friction versus force curves based on a sequence of images at a single location, each with incrementally lower loads. As a result, true maps of the coefficient of friction can be uniquely calculated for heterogeneous surfaces. These parameters are determined at a scan velocity as fast as 2 mm s −1 for microfabricated SiO 2 mesas and Au coated pits, yielding results that are identical to traditional speed measurements despite being ∼1000 times faster. To demonstrate the upper limit of sliding velocity for the custom setup, the friction properties of mica are reported from 200 µm s −1 up to 2 cm s −1 . While FCM is applicable to any AFM and scanning speed, quantitative nanotribology investigations of heterogeneous sliding or rolling components are therefore uniquely possible, even at realistic velocities for devices such as MEMS, biological implants, or data storage systems. (paper)

  7. Effect of the Grip Angle on Off-Spin Bowling Performance Parameters, Analysed with a Smart Cricket Ball

    Directory of Open Access Journals (Sweden)

    Franz Konstantin Fuss

    2018-02-01

    Full Text Available In the off-spin bowling grip, the ball is clamped between index and middle fingers. Spin bowlers attempt to select a spread angle between these two fingers that achieves comfort and optimises performance. The aim of this paper was to investigate whether the standard grip is superior to narrow and wide grips. The bowling performance parameters were obtained from a smart cricket ball. Smart ball data revealed that the performance parameters varied with grip type. The following parameters were optimum at the standard grip: spin rate, resultant torque, spin torque, peak angular acceleration, and peak power. The following parameters were optimum at standard and wide grips: efficiency. The following parameters were optimum at standard and narrow grips: pitch angle of spin axis. The following parameters were optimum at the wide grip: precession and the precession torque. In general, the data tended to show that the standard grip is most effective for spin bowling. However, more research is needed to confirm this result, because the precession and precession torque were optimum at the wide grip, suggesting that this may have a superior performance over the standard and narrow grips.

  8. Real-Time Dynamic Observation of Micro-Friction on the Contact Interface of Friction Lining

    Science.gov (United States)

    Zhang, Dekun; Chen, Kai; Guo, Yongbo

    2018-01-01

    This paper aims to investigate the microscopic friction mechanism based on in situ microscopic observation in order to record the deformation and contact situation of friction lining during the frictional process. The results show that friction coefficient increased with the shear deformation and energy loss of the surfacee, respectively. Furthermore, the friction mechanism mainly included adhesive friction in the high-pressure and high-speed conditions, whereas hysteresis friction was in the low-pressure and low-speed conditions. The mixed-friction mechanism was in the period when the working conditions varied from high pressure and speed to low pressure and speed. PMID:29498677

  9. Fuel assembly gripping device using self-locking mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Lee, G. M.; Choi, S.; Kim, K. S.; Kim, T. W.; Jeong, K. H.; Park, K. B.; Chang, M. H

    1999-07-01

    This report presents an actuating principles and structure for two kind of the fuel assembly gripping devices (Gripper-A, B) developed for SMART. The main components of these grippers are push bundle, rotation bundle, upper guide tube and chuck assembly. The rope attached to winch system on moving cask hangs gripper's push bundle. Due to a down-and-up operation of winch system, the push bundle pushes crown teeth shaped rotation bundle and then it is pushed down and rotated counter clockwise. The push-and-pull sequential operation of push bundle makes the rotation bundle is pushed, rotated and returned, moreover it makes the chuck assembly is expanded or shrunk. The expansion and shrinkage motion of chuck assembly makes the gripper latch and release the fuel assembly. Gripper-A suits for the handling of the fuel assembly with square shaped latching hole. Otherwise Gripper-B suits for a circular shaped latching hole. (author). 5 refs., 20 figs.

  10. Versatile Friction Stir Welding/Friction Plug Welding System

    Science.gov (United States)

    Carter, Robert

    2006-01-01

    A proposed system of tooling, machinery, and control equipment would be capable of performing any of several friction stir welding (FSW) and friction plug welding (FPW) operations. These operations would include the following: Basic FSW; FSW with automated manipulation of the length of the pin tool in real time [the so-called auto-adjustable pin-tool (APT) capability]; Self-reacting FSW (SRFSW); SR-FSW with APT capability and/or real-time adjustment of the distance between the front and back shoulders; and Friction plug welding (FPW) [more specifically, friction push plug welding] or friction pull plug welding (FPPW) to close out the keyhole of, or to repair, an FSW or SR-FSW weld. Prior FSW and FPW systems have been capable of performing one or two of these operations, but none has thus far been capable of performing all of them. The proposed system would include a common tool that would have APT capability for both basic FSW and SR-FSW. Such a tool was described in Tool for Two Types of Friction Stir Welding (MFS- 31647-1), NASA Tech Briefs, Vol. 30, No. 10 (October 2006), page 70. Going beyond what was reported in the cited previous article, the common tool could be used in conjunction with a plug welding head to perform FPW or FPPW. Alternatively, the plug welding head could be integrated, along with the common tool, into a FSW head that would be capable of all of the aforementioned FSW and FPW operations. Any FSW or FPW operation could be performed under any combination of position and/or force control.

  11. Slow rupture of frictional interfaces

    Science.gov (United States)

    Bar Sinai, Yohai; Brener, Efim A.; Bouchbinder, Eran

    2012-02-01

    The failure of frictional interfaces and the spatiotemporal structures that accompany it are central to a wide range of geophysical, physical and engineering systems. Recent geophysical and laboratory observations indicated that interfacial failure can be mediated by slow slip rupture phenomena which are distinct from ordinary, earthquake-like, fast rupture. These discoveries have influenced the way we think about frictional motion, yet the nature and properties of slow rupture are not completely understood. We show that slow rupture is an intrinsic and robust property of simple non-monotonic rate-and-state friction laws. It is associated with a new velocity scale cmin, determined by the friction law, below which steady state rupture cannot propagate. We further show that rupture can occur in a continuum of states, spanning a wide range of velocities from cmin to elastic wave-speeds, and predict different properties for slow rupture and ordinary fast rupture. Our results are qualitatively consistent with recent high-resolution laboratory experiments and may provide a theoretical framework for understanding slow rupture phenomena along frictional interfaces.

  12. Characterization of corticospinal activation of finger motor neurons during precision and power grip in humans

    DEFF Research Database (Denmark)

    Svane, Christian; Forman, Christian Riis; Nielsen, Jens Bo

    2018-01-01

    Direct and indirect corticospinal pathways to finger muscles may play a different role in control of the upper extremity. We used transcranial magnetic stimulation (TMS) and coherence analysis to characterize the corticospinal drive to the first dorsal interosseous (FDI) and abductor pollicis bre...... brevis (APB) when active during a precision and power grip task. In experiment 1, single motor units were recorded during precision grip and power grip in 20 adults (25.2 ± 7.1 years). Post-stimulus time histograms (PSTH) were obtained following TMS. In experiment 2, coherence and cross...... system) is equally involved in the control of both tasks. The data do not support that indirect pathways would make a larger contribution to power grip....

  13. GRIP NOAA GLOBAL HAWK IN-FLIGHT TURBULENCE SENSOR (GHIS) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP NOAA Global Hawk In-Flight Turbulence Sensor (GHIS) dataset was collected by the NOAA Global Hawk In-flight Turbulence Sensor (GHIS) instrument, which...

  14. A Monte Carlo-tuned model of the flow in the NorthGRIP area

    DEFF Research Database (Denmark)

    Grinsted, Aslak; Dahl-Jensen, Dorthe

    2002-01-01

    The North Greenland Icecore Project (NorthGRIP) drill site was chosen in order to obtain a good Eemian record. At the present depth, 3001m, the Eemian interstadial has yet to be seen. Clearly the flow in this area is poorly understood and needs further investigation. After a review of specific...... no Eemian is observed is a high basal melt rate (2.7mm/a). The melting is a consequence of a higher geothermal heat flux than the expected 51mW/m^2 of the Precambrian shield. From our analyses it is concluded that the geothermal heat flux at NorthGRIP is 98mW/m^2.The high basalmelt rate also gives rise...... to sliding at the bed. In addition to these results, an accumulationmodel has been established specifically forNorthGRIP.These results are essential for further modelling of the NorthGRIP flow and depth-age relationship...

  15. External models of frictional interaction dynamics

    Science.gov (United States)

    Tyurin, A. E.; Ismailov, G. M.; Ikonnikova, K. V.; Sarkisov, Y. S.

    2017-10-01

    This investigation suggests a method used to determine the evolution of metallic wear and friction by sliding. The friction of steel moving over brass was taken as an example. The problem of external dynamics friction is investigated through the definition of the dynamic characteristics such as damping factor and natural frequency. Some certain automatic control methods were applied for sliding friction contact, including parametric identification, ARX simulation and Newton’s dynamic equation. The suggested approach allows using amplitude-frequency characteristics to assess the dynamic factors (coefficients) under friction interaction. The research findings indicate that the proposed method allows monitoring the evolution of metallic wear and friction.

  16. Effect of Putting Grip on Eye and Head Movements During the Golf Putting Stroke

    Directory of Open Access Journals (Sweden)

    George K. Hung

    2003-01-01

    Full Text Available The objective of this article is to determine the effect of three different putting grips (conventional, cross-hand, and one-handed on variations in eye and head movements during the putting stroke. Seven volunteer novice players, ranging in age from 21 to 22 years, participated in the study. During each experimental session, the subject stood on a specially designed platform covered with artificial turf and putted golf balls towards a standard golf hole. The three different types of grips were tested at two distances: 3 and 9 ft. For each condition, 20 putts were attempted. For each putt, data were recorded over a 3-s interval at a sampling rate of 100 Hz. Eye movements were recorded using a helmet-mounted eye movement monitor. Head rotation about an imaginary axis through the top of the head and its center-of-rotation was measured by means of a potentiometer mounted on a fixed frame and coupled to the helmet. Putter-head motion was measured using a linear array of infrared phototransistors embedded in the platform. The standard deviation (STD, relative to the initial level was calculated for eye and head movements over the duration of the putt (i.e., from the beginning of the backstroke, through the forward stroke, to impact. The averaged STD for the attempted putts was calculated for each subject. Then, the averaged STDs and other data for the seven subjects were statistically compared across the three grip conditions. The STD of eye movements were greater (p < 0.1 for conventional than cross-hand (9 ft and one-handed (3 and 9 ft grips. Also, the STD of head movements were greater (p < 0.1; 3 ft for conventional than cross-hand and one-handed grips. Vestibulo-ocular responses associated with head rotations could be observed in many 9 ft and some 3 ft putts. The duration of the putt was significantly longer (p < 0.05; 3 and 9 ft for the one-handed than conventional and cross-hand grips. Finally, performance, or percentage putts made, was

  17. Effect of putting grip on eye and head movements during the golf putting stroke.

    Science.gov (United States)

    Hung, George K

    2003-03-24

    The objective of this article is to determine the effect of three different putting grips (conventional, cross-hand, and one-handed) on variations in eye and head movements during the putting stroke. Seven volunteer novice players, ranging in age from 21 to 22 years, participated in the study. During each experimental session, the subject stood on a specially designed platform covered with artificial turf and putted golf balls towards a standard golf hole. The three different types of grips were tested at two distances: 3 and 9 ft. For each condition, 20 putts were attempted. For each putt, data were recorded over a 3-s interval at a sampling rate of 100 Hz. Eye movements were recorded using a helmet-mounted eye movement monitor. Head rotation about an imaginary axis through the top of the head and its center-of-rotation was measured by means of a potentiometer mounted on a fixed frame and coupled to the helmet. Putter-head motion was measured using a linear array of infrared phototransistors embedded in the platform. The standard deviation (STD, relative to the initial level) was calculated for eye and head movements over the duration of the putt (i.e., from the beginning of the backstroke, through the forward stroke, to impact). The averaged STD for the attempted putts was calculated for each subject. Then, the averaged STDs and other data for the seven subjects were statistically compared across the three grip conditions. The STD of eye movements were greater (p < 0.1) for conventional than cross-hand (9 ft) and one-handed (3 and 9 ft) grips. Also, the STD of head movements were greater (p < 0.1; 3 ft) for conventional than cross-hand and one-handed grips. Vestibulo-ocular responses associated with head rotations could be observed in many 9 ft and some 3 ft putts. The duration of the putt was significantly longer (p < 0.05; 3 and 9 ft) for the one-handed than conventional and cross-hand grips. Finally, performance, or percentage putts made, was significantly

  18. Adaptive control of grip force to compensate for static and dynamic torques during object manipulation.

    Science.gov (United States)

    Crevecoeur, F; Giard, T; Thonnard, J-L; Lefèvre, P

    2011-12-01

    Manipulating a cup by the handle requires compensating for the torque induced by the moment of the mass of the cup relative to the location of the handle. In the present study, we investigated the control strategy of subjects asked to perform grip-lift movements with an object with center of mass located away from the grip axis. Participants were asked to lift the manipulandum with a two-fingers precision grip and stabilize it in front of a visual target. Subjects showed a gradual and slow adaptation of the grip-force scaling across trials: the grip force tended to decrease slowly, and the temporal coordination between grip-force and load-torque rates displayed gradually, better-coordinated patterns. Importantly, this adaptation was much slower than the stabilization of the same parameters measured either when no torque came into play or after previous adaptation to the presence of a torque. In contrast, the maximum rotation induced by the torque was controlled efficiently after only few trials, and an unexpected decrease in the tangential torque produced significant overcompensation. An unexpected increase in torque produced a consistent opposite effect. This shows that the compensation for the dynamic torque was based on an anticipatory, dynamic counter-torque produced by the arm and wrist motor commands. The comparatively slow stabilization of grip-force control suggests a specific adaptation process engaged by the presence of the torque. This paradigm, including tangential torques, clearly constitutes a powerful tool to extract the adaptive component of grip control during object manipulation.

  19. Adaptive grip force is modulated by subthalamic beta activity in Parkinson's disease patients

    Directory of Open Access Journals (Sweden)

    Lukas L. Imbach

    2015-01-01

    Conclusion: The time-locked suppression of beta oscillatory activity in the STN is in line with previous reports of beta ERD prior to voluntary movements. Our results show that the STN is involved in anticipatory grip force control in PD patients. The difference in the phasic beta ERD between the two tasks and the reduction of cortico-subthalamic synchronization suggests that qualitatively different neuronal network states are involved in different grip force control tasks.

  20. Effects of Fat Grip Training on Muscular Strength and Driving Performance in Division I Male Golfers.

    Science.gov (United States)

    Cummings, Patrick M; Waldman, Hunter S; Krings, Ben M; Smith, JohnEric W; McAllister, Matthew J

    2018-01-01

    Cummings, PM, Waldman, HS, Krings, BM, Smith, JW, and McAllister, MJ. Effects of fat grip training on muscular strength and driving performance in division I male golfers. J Strength Cond Res 32(1): 205-210, 2018-Fat grip (FG) training is implemented into strength and conditioning programs with the overall goal of increasing grip strength. Previous research assessing the effect of training with increased grip diameters compared with standard Olympic bar diameters has mainly been in acute settings. Therefore, the purpose of this study was to examine to effects FG training compared with normal diameter grip (CON) training during an 8-week periodized resistance training (RT) program in division I male golfers. Subjects (n = 10) were randomly assigned into 2 groups: the FG group (n = 5, scoring average: 75.4 ± 2.0) and CON group (n = 5, scoring average: 75.0 ± 0.5). Both groups participated in 8 weeks of RT (3 d·wk). The FG group completed every lift and repetition using FG, compared with the CON training group which used normal diameter bars. Pretraining and posttraining performance variables included swing speed, ball speed, driving distance, driving carry, maximum pull-ups to failure, right and left hand grip strength, and 1 repetition max trap-bar deadlift. The FG group demonstrated significant increases (p ≤ 0.05) in ball speed, carry, drive distance, and left hand grip strength after 8 weeks of RT. In a population, such as low-handicap division I male golfers, FG training may allow for athletes to increase golf-specific performance after 8 weeks of periodized RT. Strength and conditioning coaches may use FG training over the course of a training program with athletes who require adequate grip strength to further elicit training adaptations.

  1. Grip strength in mice with joint inflammation: A rheumatology function test sensitive to pain and analgesia.

    Science.gov (United States)

    Montilla-García, Ángeles; Tejada, Miguel Á; Perazzoli, Gloria; Entrena, José M; Portillo-Salido, Enrique; Fernández-Segura, Eduardo; Cañizares, Francisco J; Cobos, Enrique J

    2017-10-01

    Grip strength deficit is a measure of pain-induced functional disability in rheumatic disease. We tested whether this parameter and tactile allodynia, the standard pain measure in preclinical studies, show parallels in their response to analgesics and basic mechanisms. Mice with periarticular injections of complete Freund's adjuvant (CFA) in the ankles showed periarticular immune infiltration and synovial membrane alterations, together with pronounced grip strength deficits and tactile allodynia measured with von Frey hairs. However, inflammation-induced tactile allodynia lasted longer than grip strength alterations, and therefore did not drive the functional deficits. Oral administration of the opioid drugs oxycodone (1-8 mg/kg) and tramadol (10-80 mg/kg) induced a better recovery of grip strength than acetaminophen (40-320 mg/kg) or the nonsteroidal antiinflammatory drugs ibuprofen (10-80 mg/kg) or celecoxib (40-160 mg/kg); these results are consistent with their analgesic efficacy in humans. Functional impairment was generally a more sensitive indicator of drug-induced analgesia than tactile allodynia, as drug doses that attenuated grip strength deficits showed little or no effect on von Frey thresholds. Finally, ruthenium red (a nonselective TRP antagonist) or the in vivo ablation of TRPV1-expressing neurons with resiniferatoxin abolished tactile allodynia without altering grip strength deficits, indicating that the neurobiology of tactile allodynia and grip strength deficits differ. In conclusion, grip strength deficits are due to a distinct type of pain that reflects an important aspect of the human pain experience, and therefore merits further exploration in preclinical studies to improve the translation of new analgesics from bench to bedside. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  2. Improvement of handle grip using reverse engineering, CAE and Rapid Prototyping

    Directory of Open Access Journals (Sweden)

    Stoklasek Pavel

    2016-01-01

    Full Text Available The overwhelming majority of manual operations is even nowadays performed by using manual hand tools. These tools can be divided into 2 groups – hand tools designed for general use or a single-purpose hand tools for special operations. Tool described in this paper is used in assembling operation in the completion of electric motor. During the design of the existing tools the requirements for a functional part of the tool (lifespan, inability to damage the engine installation were fully considered, demands for ergonomic grip area, however, were not taken into account. Long-term use of incorrectly designed tool causes carpal tunnel syndrome, hand-arm vibration syndrome, diminished sensitivity or tingling in the fingers of workers. These difficulties can be reduced or entirely eliminated due to proper design of the grip of hand tool. Most authors focus on adjusting the grip for optimum ergonomics at individual types of grips (cylindrical, palmar, lateral, etc.. However, as already mentioned, there are tools for specific operations when the working area is limited by space or a specific type of load on the grip is needed. In some cases, it is often necessary to change the type of grip or combine different types of grips. This paper describes the design of an optimal grip of hand tool used for specific operation when assembling motors. Design of prototype mold and production of functional prototypes for ergonomics assessment directly in the workplace were realized. New design of handle should reduce the risk primarily of developing carpal tunnel in long-term use.

  3. The Reality of Casimir Friction

    Directory of Open Access Journals (Sweden)

    Kimball A. Milton

    2016-04-01

    Full Text Available For more than 35 years theorists have studied quantum or Casimir friction, which occurs when two smooth bodies move transversely to each other, experiencing a frictional dissipative force due to quantum electromagnetic fluctuations, which break time-reversal symmetry. These forces are typically very small, unless the bodies are nearly touching, and consequently such effects have never been observed, although lateral Casimir forces have been seen for corrugated surfaces. Partly because of the lack of contact with observations, theoretical predictions for the frictional force between parallel plates, or between a polarizable atom and a metallic plate, have varied widely. Here, we review the history of these calculations, show that theoretical consensus is emerging, and offer some hope that it might be possible to experimentally confirm this phenomenon of dissipative quantum electrodynamics.

  4. Does Grip Strength Reflect Isokinetic Muscle Strength in Lower Limbs in Patients with CIDP?

    Science.gov (United States)

    Knak, Kirsten L; Andersen, Linda K; Christiansen, Ingelise; Markvardsen, Lars K

    2018-03-30

    Introduction Grip strength is a common measure of general muscle strength in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). However, it is important to investigate the correlation and responsiveness of grip strength compared to isokinetic muscle strength (IKS) and function of the lower limbs. Methods Seventy patients with CIDP were evaluated with grip strength, IKS and functional measures of the lower limbs. Reevaluation was done after 2 and 10/12 weeks. Correlation and response analyses were performed. Results Grip strength correlated with IKS ankle (maximum Spearman's rank correlation (R S ) = 0.58) and with walking performance (maximum R S = -0.38). IKS ankle was more responsive to detect change (Standardized Response Mean (SRM) = 0.57) than grip strength (SRM = 0.27). Discussion Grip strength does not seem to be an appropriate surrogate measure of IKS and function of the lower limbs in patients with CIDP. This article is protected by copyright. All rights reserved. © 2018 Wiley Periodicals, Inc.

  5. Age-associated changes in hand grip and quadriceps muscle strength ratios in healthy adults.

    Science.gov (United States)

    Samuel, Dinesh; Wilson, Keely; Martin, Helen J; Allen, Robert; Sayer, Avan Aihie; Stokes, Maria

    2012-06-01

    Muscle strength may decline with age differentially in the upper and lower limbs. This information is difficult to capture through a single measure. The present study therefore aimed to characterize the relative changes in handgrip and lower limb muscle strength with aging by expressing them as a ratio. Thirty-eight healthy volunteers aged 20-82 years performed maximal voluntary contractions (MVC) of quadriceps and handgrip using a custom-built transducer and a Jamar dynamometer respectively. The grip-quadriceps ratios for young adults was similar in males and females (0.75); indicating knee extensor force exceeded grip force by approximately 25%. Ratios were increased in older adults (p=0.05), and strength of the two muscle groups was approximately equal (1.1). Pearson's correlation coefficients for grip against quadriceps strength were r=0.63 (young males), r=0.83 (young females), r=0.35 (older males) and r=0.05 (older females). The ratio used demonstrated clear differences between the age groups. The reduced muscle strength with increasing age was expected, but the higher grip/quadriceps strength ratios quantify a greater loss of quadriceps than grip strength with aging. It remains to be investigated whether the relatively greater rate of decline in quadriceps strength seen in healthy older people is more exaggerated in those who are frail, which would have implications for using grip strength as a physical marker of lower limb strength and function in those at risk of immobility and falls.

  6. Hold, grasp, clutch or grab: consumer grip choices during food container opening.

    Science.gov (United States)

    Rowson, J; Yoxall, A

    2011-07-01

    Society is ageing and sadly that ageing leads to a host of issues, not least a society in which the majority are likely to have some loss of strength and dexterity. This can lead to complications in undertaking everyday tasks such as using transport, bathing or even handling and opening food. Packaging has to provide a multitude of services; to protect and preserve the product, to provide information to the consumer and not least to allow access to the contents. This access to packaging--or 'openability'--has become a significant issue for designers and manufacturers with the change in demographics as described above. Understanding the choices consumers make in how they manipulate packaging can help designers produce packaging that is more able to meet the requirements of modern society. Studies previously undertaken by the authors showed that consumers did use different grips when opening packaging and that certain grips were theoretically more comfortable and stronger than others. This paper outlines a further study whereby consumers were asked to apply the most common grips to a specially designed torque measuring device. Details were taken about the consumers: age, gender, occupation, hand size, plus their preferred grip choice for packaging of this type. The study showed that typically women chose a grip that maximised their opportunity of opening the closure and that this grip choice was more limited than that available for men. This has implications for inclusive design of many everyday products. Copyright © 2010 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  7. Manual action verbs modulate the grip force of each hand in unimanual or symmetrical bimanual tasks.

    Science.gov (United States)

    da Silva, Ronaldo Luis; Labrecque, David; Caromano, Fátima Aparecida; Higgins, Johanne; Frak, Victor

    2018-01-01

    Manual action verbs modulate the right-hand grip force in right-handed subjects. However, to our knowledge, no studies demonstrate the ability to accomplish this modulation during bimanual tasks nor describe their effect on left-hand behavior in unimanual and bimanual tasks. Using load cells and word playlists, we evaluated the occurrence of grip force modulation by manual action verbs in unimanual and symmetrical bimanual tasks across the three auditory processing phases. We found a significant grip force increase for all conditions compared to baseline, indicating the occurrence of modulation. When compared to each other, the grip force variation from baseline for the three phases of both hands in the symmetrical bimanual task was not different from the right-hand in the unimanual task. The left-hand grip force showed a lower amplitude for auditory phases 1 and 2 when compared to the other conditions. The right-hand grip force modulation became significant from baseline at 220 ms after the word onset in the unimanual task. This moment occurred earlier for both hands in bimanual task (160 ms for the right-hand and 180 for the left-hand). It occurred later for the left-hand in unimanual task (320 ms). We discuss the hypothesis that Broca's area and Broca's homologue area likely control the left-hand modulation in a unilateral or a bilateral fashion. These results provide new evidence for understanding the linguistic function processing in both hemispheres.

  8. Manual action verbs modulate the grip force of each hand in unimanual or symmetrical bimanual tasks.

    Directory of Open Access Journals (Sweden)

    Ronaldo Luis da Silva

    Full Text Available Manual action verbs modulate the right-hand grip force in right-handed subjects. However, to our knowledge, no studies demonstrate the ability to accomplish this modulation during bimanual tasks nor describe their effect on left-hand behavior in unimanual and bimanual tasks. Using load cells and word playlists, we evaluated the occurrence of grip force modulation by manual action verbs in unimanual and symmetrical bimanual tasks across the three auditory processing phases. We found a significant grip force increase for all conditions compared to baseline, indicating the occurrence of modulation. When compared to each other, the grip force variation from baseline for the three phases of both hands in the symmetrical bimanual task was not different from the right-hand in the unimanual task. The left-hand grip force showed a lower amplitude for auditory phases 1 and 2 when compared to the other conditions. The right-hand grip force modulation became significant from baseline at 220 ms after the word onset in the unimanual task. This moment occurred earlier for both hands in bimanual task (160 ms for the right-hand and 180 for the left-hand. It occurred later for the left-hand in unimanual task (320 ms. We discuss the hypothesis that Broca's area and Broca's homologue area likely control the left-hand modulation in a unilateral or a bilateral fashion. These results provide new evidence for understanding the linguistic function processing in both hemispheres.

  9. Skin friction blistering: computer model.

    Science.gov (United States)

    Xing, Malcolm; Pan, Ning; Zhong, Wen; Maibach, Howard

    2007-08-01

    Friction blisters, a common injury in sports and military operations, can adversely effect or even halt performance. Given its frequency and hazardous nature, recent research efforts appear limited. Blistering can be treated as a delamination phenomenon; similar issues in materials science have been extensively investigated in theory and experiment. An obstacle in studying blistering is the difficulty of conducting experiment on humans and animals. Computer modeling thus becomes a preferred tool. This paper used a dynamic non-linear finite-element model with a blister-characterized structure and contact algorithm for outer materials and blister roof to investigate the effects on deformation and stress of an existing blister by changing the friction coefficient and elastic modulus of the material in contact with the blister. Through the dynamics mode and harmonic frequency approach, we demonstrated that the loading frequency leads to dramatic changes of displacement and stress in spite of otherwise similar loading. Our simulations show that an increased friction coefficient does not necessarily result in an increase in either the stress on the hot spot or blister deformation; local maximum friction stress and Von Mises stress exist for some friction coefficients over the wide range examined here. In addition, the stiffness of contact material on blistering is also investigated, and no significant effects on deformation and Von Mises stress are found, again at the range used. The model and method provided here may be useful for evaluating loading environments and contact materials in reducing blistering incidents. The coupling finite-element model can predict the effects of friction coefficient and contacting materials&apos stiffness on blister deformation and hot spot stress.

  10. Machine Learning of Fault Friction

    Science.gov (United States)

    Johnson, P. A.; Rouet-Leduc, B.; Hulbert, C.; Marone, C.; Guyer, R. A.

    2017-12-01

    We are applying machine learning (ML) techniques to continuous acoustic emission (AE) data from laboratory earthquake experiments. Our goal is to apply explicit ML methods to this acoustic datathe AE in order to infer frictional properties of a laboratory fault. The experiment is a double direct shear apparatus comprised of fault blocks surrounding fault gouge comprised of glass beads or quartz powder. Fault characteristics are recorded, including shear stress, applied load (bulk friction = shear stress/normal load) and shear velocity. The raw acoustic signal is continuously recorded. We rely on explicit decision tree approaches (Random Forest and Gradient Boosted Trees) that allow us to identify important features linked to the fault friction. A training procedure that employs both the AE and the recorded shear stress from the experiment is first conducted. Then, testing takes place on data the algorithm has never seen before, using only the continuous AE signal. We find that these methods provide rich information regarding frictional processes during slip (Rouet-Leduc et al., 2017a; Hulbert et al., 2017). In addition, similar machine learning approaches predict failure times, as well as slip magnitudes in some cases. We find that these methods work for both stick slip and slow slip experiments, for periodic slip and for aperiodic slip. We also derive a fundamental relationship between the AE and the friction describing the frictional behavior of any earthquake slip cycle in a given experiment (Rouet-Leduc et al., 2017b). Our goal is to ultimately scale these approaches to Earth geophysical data to probe fault friction. References Rouet-Leduc, B., C. Hulbert, N. Lubbers, K. Barros, C. Humphreys and P. A. Johnson, Machine learning predicts laboratory earthquakes, in review (2017). https://arxiv.org/abs/1702.05774Rouet-LeDuc, B. et al., Friction Laws Derived From the Acoustic Emissions of a Laboratory Fault by Machine Learning (2017), AGU Fall Meeting Session S025

  11. Genetic influences on the development of grip strength in adolescence.

    Science.gov (United States)

    Isen, Joshua; McGue, Matt; Iacono, William

    2014-06-01

    Enhanced physical strength is a secondary sex characteristic in males. Sexual dimorphism in physical strength far exceeds sex differences in stature or total body mass, suggesting a legacy of intense sexual selection. Upper-body strength is a particularly promising marker of intrasexual competitiveness in young men. Consequently, it is assumed that sex-influenced gene expression contributes to the development of physical strength. It is unclear, however, whether the underlying sources of individual differences in strength development are comparable across sex. We obtained three measurements of hand-grip strength (HGS) over a six-year period spanning adolescence in male and female same-sex twins (N = 2,513). Biometrical latent growth models were used to partition the HGS variance at age 11 (intercept) and its growth over time (slope) into genetic and environmental components. Results demonstrated that variance around the intercept was highly heritable in both males and females (88% and 79%, respectively). In males, variance around the slope exceeded that of the intercept, while the reverse held for females. Additive genetic effects accounted for most (80%) of the variance around the slope in males, but were of less importance in females (heritability = 28%). Absolute genetic variance around the slope was nearly nine-fold higher in males. This striking disparity suggests that the developmental processes shaping HGS growth are different between the sexes. We propose that this might account for the sex-specific pattern of associations between HGS and external measures (e.g., digit ratio and physical aggression) typically reported in the literature. Our results underscore the role of endogenous androgenic influences in the development of physical strength. © 2014 Wiley Periodicals, Inc.

  12. Literature survey on microscopic friction modeling

    NARCIS (Netherlands)

    Hol, J.

    2010-01-01

    To better understand contact and friction conditions, experimental and theoretical studies have been performed in order to take microscopic dependencies into account. Friction is developed on microscopic level by adhesion between contacting asperities, the ploughing effect between asperities and the

  13. Analytical and numerical investigation of bolted steel ring flange connection for offshore wind monopile foundations

    Science.gov (United States)

    Madsen, C. A.; Kragh-Poulsen, J.-C.; Thage, K. J.; Andreassen, M. J.

    2017-12-01

    The monopile foundation is the dominant solution for support of wind turbines in offshore wind farms. It is normally grouted to the transition piece which connects the foundation to the turbine. Currently, the bolted steel ring flange connection is investigated as an alternative. The monopile--transition piece connection has specific problems, such as out-of-verticality and installation damage from driving the MP into the seabed and it is not fully known how to design for these. This paper presents the status of the ongoing development work and an estimate of what still needs to be covered in order to use the connection in practice. This involves presentation of an analytical and non-linear FE analysis procedure for the monopile-transition piece connection composed of two L flanges connected with preloaded bolts. The connection is verified for ultimate and fatigue limit states based on an integrated load simulation carried out by the turbine manufacturer.

  14. Flanged joints with contact outside the bolt circle: ASME Part B design rules

    International Nuclear Information System (INIS)

    Rodabaugh, E.C.; Moore, S.E.

    1976-05-01

    The ASME Boiler and Pressure Vessel Code, Section VIII, Division 1, gives rules which are subdivided into ''Part A'' and ''Part B''. Part A covers flanged joints where contact between flanges occurs through a gasket located inside the bolt holes. Part B covers flanged joints with contact outside the bolt holes. This report (a) summarizes the theory for Part B flanged joints, (b) presents examples which show the significant differences between Part A flanged joints and Part B flanged joints, (c) presents the available test data relevant to the characteristics of Part B flanged joints, (d) gives listings of two computer programs which can be used to evaluate the characteristics of Part B flanged joints, and (e) gives recommendations for Code revisions and other aspects of Part B flanged-joint design

  15. PERL - European research project on characterization of gaskets for bolted flange connections

    International Nuclear Information System (INIS)

    Kockelmann, H.; Hahn, R.

    2004-01-01

    Great progress was observed in the European standardization in the last years in the field of the design of floating type bolted flange connections. New design rules were developed (EN 1591) which include new definitions of gasket characteristics for the calculation of floating type flanged joints. In addition a new gasket testing standard was drafted (prEN 13555) which assures a comprehensive characterization of gaskets for bolted flanged joints. This draft standard contains some new features which were examined and validated within the European research project PERL (Pressure Equipment - Reduction of Leak Rate). The gasket testing strategy laid down in prEN 13555 is presented in this paper. Some testing results highlighten the measuring procedures and the evaluation of the gasket characteristics. (orig.)

  16. STAMINA OF A GASKETED BOLTED FLANGED PIPE JOINT UNDER DYNAMIC LOADING

    Directory of Open Access Journals (Sweden)

    Muhammad Abid

    2016-11-01

    Full Text Available Gasketed bolted flange joints are the most critical components in pipelines for their sealing and strength under operating conditions. Most of the work available in literature is under static loading, whereas in industry, cyclic loads are applied due to the vibrating machinery such as motors, pumps, sloshing in offshore applications and in the ships etc. In this study a three dimensional finite element analysis of a gasketed joint is carried out using a spiral wound gasket under bolt up and dynamic operating conditions (internal pressure, axial and bending singly and in combination. The cyclic axial loads are concluded relatively more challenging for both the sealing and strength of the joint. Higher magnitudes of loads and frequencies are also observed more challenging to the joints performance.

  17. Remote Impedance-based Loose Bolt Inspection Using a Radio-Frequency Active Sensing Node

    Energy Technology Data Exchange (ETDEWEB)

    Park, Seung Hee; Yun, Chung Bang [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Inman, Daniel J. [Virginia Polytechnic Institute and State University, Virginia (United States)

    2007-06-15

    This paper introduces an active sensing node using radio-frequency (RF) telemetry. This device has brought the traditional impedance-based structural health monitoring (SHM) technique to a new paradigm. The RF active sensing node consists of a miniaturized impedance measuring device (AD5933), a microcontroller (ATmega128L), and a radio frequency (RF) transmitter (XBee). A macro-fiber composite (MFC) patch interrogates a host structure by using a self-sensing technique of the miniaturized impedance measuring device. All the process including structural interrogation, data acquisition, signal processing, and damage diagnostic is being performed at the sensor location by the microcontroller. The RF transmitter is used to communicate the current status of the host structure. The feasibility of the proposed SHM strategy is verified through an experimental study inspecting loose bolts in a bolt-jointed aluminum structure

  18. The Bearing Strength and Fracture Behavior of Bolted Connections in Two Aluminum Alloys

    Science.gov (United States)

    Tinl, N.; Menzemer, C. C.; Manigandan, K.; Srivatsan, T. S.

    2013-11-01

    In this paper, the bearing capacity, taken as a combination of strength, elongation, and failure by fracture characteristics of bolt holes in two aluminum alloys, 5052-H32 and 6061-T6, that were deformed in uniaxial tension is presented and discussed. The specific role played by bolt hole confinement on the bearing capacity of each aluminum alloy is highlighted. An increase in the bearing ratio caused plastic deformation around the holes to gradually increase. For both the chosen aluminum alloys the average bearing ratio at the time of failure of the test sample was found to vary with end distance. The experimentally determined strength was observably larger than the calculated bearing strength obtained using guaranteed minimum mechanical properties and recommended mathematical relationships. The nature of final fracture of each aluminum alloy is carefully examined and the intrinsic features present on the fracture surface are rationalized in concurrence with macroscopic mechanical response.

  19. Suicide with two makes of captive-bolt guns (livestock stunners) fired simultaneously to the forehead.

    Science.gov (United States)

    Pircher, Rebecca; Geisenberger, Dorothee; Große Perdekamp, Markus; Neukamm, Merja; Pollak, Stefan; Schmidt, Ulrike; Thierauf-Emberger, Annette

    2017-11-01

    In humans, most fatalities from slaughterer's guns are suicides committed by persons familiar with stunning devices. The great majority of cases accounts for shots to the head, especially the frontal region. Only a small number of two subsequent cranial shots from captive-bolt humane killers have been reported up to now. In the case presented by the authors, a suicide by simultaneous shots to the head fired from two different makes of captive-bolt guns (one of them having two separate outlets for the combustion gases in the muzzle plane, the other type having no additional openings) is described for the first time. One of the shooting devices remained in firm contact with the left hand and produced patterned staining from rust corresponding to the surface relief of the gun. The medicolegal and criminalistic aspects of this unique case are discussed with reference to the pertinent literature.

  20. Methods and Devices used to Measure Friction

    DEFF Research Database (Denmark)

    Jeswiet, Jack; Arentoft, Mogens; Henningsen, Poul

    2004-01-01

    . To gain a good understanding of the mechanisms at the interface and to be able to verify the friction and tribology models that exist, friction sensors are needed. Designing sensors to measure friction-stress in metal working has been pursued by many researchers. This paper surveys methods, which have...... been tried in the past and discusses some of the recent sensor designs, which can now be used to measure Friction in both production situations and for research purposes....

  1. Apparatus for measurement of coefficient of friction

    Science.gov (United States)

    Slifka, A. J.; Siegwarth, J. D.; Sparks, L. L.; Chaudhuri, Dilip K.

    1990-01-01

    An apparatus designed to measure the coefficient of friction in certain controlled atmospheres is described. The coefficient of friction observed during high-load tests was nearly constant, with an average value of 0.56. This value is in general agreement with that found in the literature and also with the initial friction coefficient value of 0.67 measured during self-mated friction of 440C steel in an oxygen environment.

  2. A field theoretic model for static friction

    OpenAIRE

    Mahyaeh, I.; Rouhani, S.

    2013-01-01

    We present a field theoretic model for friction, where the friction coefficient between two surfaces may be calculated based on elastic properties of the surfaces. We assume that the geometry of contact surface is not unusual. We verify Amonton's laws to hold that friction force is proportional to the normal load.This model gives the opportunity to calculate the static coefficient of friction for a few cases, and show that it is in agreement with observed values. Furthermore we show that the ...

  3. Dynamic modeling method of the bolted joint with uneven distribution of joint surface pressure

    Science.gov (United States)

    Li, Shichao; Gao, Hongli; Liu, Qi; Liu, Bokai

    2018-03-01

    The dynamic characteristics of the bolted joints have a significant influence on the dynamic characteristics of the machine tool. Therefore, establishing a reasonable bolted joint dynamics model is helpful to improve the accuracy of machine tool dynamics model. Because the pressure distribution on the joint surface is uneven under the concentrated force of bolts, a dynamic modeling method based on the uneven pressure distribution of the joint surface is presented in this paper to improve the dynamic modeling accuracy of the machine tool. The analytic formulas between the normal, tangential stiffness per unit area and the surface pressure on the joint surface can be deduced based on the Hertz contact theory, and the pressure distribution on the joint surface can be obtained by the finite element software. Futhermore, the normal and tangential stiffness distribution on the joint surface can be obtained by the analytic formula and the pressure distribution on the joint surface, and assigning it into the finite element model of the joint. Qualitatively compared the theoretical mode shapes and the experimental mode shapes, as well as quantitatively compared the theoretical modal frequencies and the experimental modal frequencies. The comparison results show that the relative error between the first four-order theoretical modal frequencies and the first four-order experimental modal frequencies is 0.2% to 4.2%. Besides, the first four-order theoretical mode shapes and the first four-order experimental mode shapes are similar and one-to-one correspondence. Therefore, the validity of the theoretical model is verified. The dynamic modeling method proposed in this paper can provide a theoretical basis for the accurate dynamic modeling of the bolted joint in machine tools.

  4. Experimental study on tunnel lining joints temporarily strengthened by SMA bolts

    International Nuclear Information System (INIS)

    Wu, Bo; Ou, Yunlong

    2014-01-01

    Shield tunnels have been widely used in city metros all over the world. During the long-term period of the metro operation, the joints of shield tunnel’s neighboring segments may degrade due to some environmental factors, leading to the increasing of the joint opening and some resulting adverse consequences. In this paper, a temporary strengthening method by using shape memory alloy (SMA) bolts is proposed and experimentally studied for the joints of neighboring segments, and a revised electric heating method which suits with the strengthening method is presented and experimentally validated for the SMA bolts. The purpose of the proposed temporary strengthening method is to create favorable conditions for the following permanent strengthening. Test results show that: (a) for the joints of shield tunnel’s neighboring segments, the strengthening method can effectively reduce the joint opening, joint deflection, concrete strain in joint’s compression zone, and strain of joint’s steel bolts; (b) the revised electric heating method can be used to heat the SMA rod to a temperature higher than the SMA’s austenite finish temperature quickly, and the average heating rate related to Type 2 inner resistance element is larger than that related to Type 1 inner resistance element; and (c) the reduction percentages of the joint opening increment, joint deflection, concrete strain in joint’s compression zone, and strain of joint’s steel bolts for Specimen I are all larger than those for Specimen II, implying that the less the joint opening is, the more significant the strengthening effect is. (paper)

  5. FFTF report: drilled-in expansion bolts under static and alternating load

    Energy Technology Data Exchange (ETDEWEB)

    Tsang, H.S.

    1976-10-01

    The objective of this investigation was to establish the allowable design loads (tension, shear, and combined load) for expansion bolts to be installed in regular 4000 psi mix concrete, Magnetite 5000 psi mix concrete, and Steel Shot 5000 psi mix concrete at the Fast Flux Test Facility. The test loads included Static Loads and Alternating Loads which simulate the dynamic loads of vibratory equipment and dynamic earthquake loads.

  6. Application of Long Expansion Rock Bolt Support in the Underground Mines of Legnica-Głogów Copper District

    Science.gov (United States)

    Skrzypkowski, Krzysztof; Korzeniowski, Waldemar; Zagórski, Krzysztof; Dudek, Piotr

    2017-09-01

    In the underground mines of the Legnica-Głogów Copper District (LGOM) the main way to protect the room excavation is the use of a rock bolt support. For many years, it has proven to be an efficient security measure in excavations which met all safety standards and requirements. The article presents the consumption of the rock bolt support in the Mining Department "Polkowice-Sieroszowice" in the years 2010-2015 as well as the number of bolt supports that were used to secure the excavations. In addition, it shows the percentage of bolt supports that were used to conduct rebuilding work and cover the surface of exposed roofs. One of the factors contributing to the loss of the functionality of bolt supports is corrosion whose occurrence may lead directly to a reduction in the diameter of rock bolt support parts, in particular rods, bearing plates and nuts. The phenomenon of the corrosion of the bolt support and its elements in underground mining is an extremely common phenomenon due to the favorable conditions for its development in mines, namely high temperature and humidity, as well as the presence of highly aggressive water. This involves primarily a decrease in the capacity of bolt support construction, which entails the need for its strengthening, and often the need to perform the reconstruction of the excavation. The article presents an alternative for steel bearing plates, namely plates made using the spatial 3D printing technology. Prototype bearing plates were printed on a 3D printer Formiga P100 using the "Precymit" material. The used printing technology was SLS (Selective Laser Sintering), which is one of the most widely used technologies among all the methods of 3D printing for the short series production of the technical parts of the final product. The article presents the stress-strain characteristic of the long expansion connected rock bolt support OB25 with a length of 3.65 m. A rock bolt support longer than 2.6 m is an additional bolt support in

  7. Asbestos free friction composition for brake linings

    Indian Academy of Sciences (India)

    An asbestos free friction material composite for brake linings is synthesized containing fibrous reinforcing constituents, friction imparting and controlling additives, elastomeric additives, fire retarding components and a thermosetting resin. The composite shows exemplary friction characteristics and has great resistance to ...

  8. Friction tensor concept for textured surfaces

    Indian Academy of Sciences (India)

    Depending on the sliding direction the coefficient of friction varies between maximum and minimum for textured surfaces. For random surfaces without any texture the friction coefficient becomes independent of the sliding direction. This paper proposes the concept of a friction tensor analogous to the heat conduction tensor ...

  9. Bolted join strength under parallel to grain double shear in guadua angustifolia structures

    Directory of Open Access Journals (Sweden)

    Fabián Augusto Lamus Báez

    2014-01-01

    Full Text Available In a bolted joint of structures that use Guadua angustifolia as the main supporting material, the resistance to the double metal shears paralleled to fiber could be influenced by an extensive list of parameters including parallel to fiber crushing resistance, parallel to metal fiber resistance of the wall and the contact area between elements in the joint. This paper presents experimental results for the resistance to the double metal shears paralleled to fiber, when the element is loaded under compression, for different culm diameters. Moreover, we studied the influence of the bolt diameter and culm thickness in the joint resistance. The tests were conducted on specimens of Guadua angustifolia with variable diameters between seven and fourteen centimeter where bolts of 3/8, 1/2 and 3/4" diameter were used. The Guadua tested came from the outskirts of Armenia in Colombia. It was found that the great amount of the double metal shears paralleled to fiber in the joint is provided by parallel to fiber crushing resistance of the Guadua.

  10. The Load Distribution in Bolted or Riveted Joints in Light-Alloy Structures

    Science.gov (United States)

    Vogt, F.

    1947-01-01

    This report contains a theoretical discussion of the load distribution in bolted or riveted joints in light-alloy structures which is applicable not only for loads below the limit of proportionality but also for loads above this limit. The theory is developed for double and single shear joints. The methods given are illustrated by numerical examples and the values assumed for the bolt (or rivet) stiffnesses are based partly on theory and partly on known experimental values. It is shown that the load distribution does not vary greatly with the bolt (or rivet) stiffnesses and that for design purposes it is usually sufficient to know their order of magnitude. The theory may also be directly used for spot-welded structures and, with small modifications, for seam-welded structures, The computational work involved in the methods described is simple and may be completed in a reasonable time for most practical problems. A summary of earlier theoretical and experimental investigations on the subject is included in the report.

  11. Holographic description of Kerr-Bolt-AdS-dS spacetimes

    International Nuclear Information System (INIS)

    Chen, B.; Ghezelbash, A.M.; Kamali, V.; Setare, M.R.

    2011-01-01

    We show that there exists a holographic 2D CFT description of a Kerr-Bolt-AdS-dS spacetime. We first consider the wave equation of a massless scalar field propagating in extremal Kerr-Bolt-AdS-dS spacetimes and find in the 'near region', the wave equation in extremal limit could be written in terms of the SL(2,R) quadratic Casimir. This suggests that there exist dual CFT descriptions of these black holes. In the probe limit, we compute the scattering amplitudes of the scalar off the extremal black holes and find perfect agreement with the CFT prediction. Furthermore we study the holographic description of the generic four-dimensional non-extremal Kerr-Bolt-AdS-dS black holes. We find that if focusing on the near-horizon region, for the massless scalar scattering in the low-frequency limit, the radial equation could still be rewritten as the SL(2,R) quadratic Casimir, suggesting the existence of dual 2D description. We read the temperatures of the dual CFT from the conformal coordinates and obtain the central charges by studying the near-horizon geometry of near-extremal black holes. We recover the macroscopic entropy from the microscopic counting. We also show that for the super-radiant scattering, the retarded Green's functions and the corresponding absorption cross sections are in perfect match with CFT prediction.

  12. Holographic description of Kerr-Bolt-AdS-dS spacetimes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, B., E-mail: bchen01@pku.edu.c [Department of Physics, and State Key Laboratory of Nuclear Physics and Technology, and Center for High Energy Physics, Peking University, Beijing 100871 (China); Ghezelbash, A.M., E-mail: masoud.ghezelbash@usask.c [Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 (Canada); Kamali, V., E-mail: vkamali1362@gmail.co [Department of Campus of Bijar, Kurdistan University, Bijar (Iran, Islamic Republic of); Setare, M.R., E-mail: rezakord@ipm.i [Department of Campus of Bijar, Kurdistan University, Bijar (Iran, Islamic Republic of)

    2011-07-01

    We show that there exists a holographic 2D CFT description of a Kerr-Bolt-AdS-dS spacetime. We first consider the wave equation of a massless scalar field propagating in extremal Kerr-Bolt-AdS-dS spacetimes and find in the 'near region', the wave equation in extremal limit could be written in terms of the SL(2,R) quadratic Casimir. This suggests that there exist dual CFT descriptions of these black holes. In the probe limit, we compute the scattering amplitudes of the scalar off the extremal black holes and find perfect agreement with the CFT prediction. Furthermore we study the holographic description of the generic four-dimensional non-extremal Kerr-Bolt-AdS-dS black holes. We find that if focusing on the near-horizon region, for the massless scalar scattering in the low-frequency limit, the radial equation could still be rewritten as the SL(2,R) quadratic Casimir, suggesting the existence of dual 2D description. We read the temperatures of the dual CFT from the conformal coordinates and obtain the central charges by studying the near-horizon geometry of near-extremal black holes. We recover the macroscopic entropy from the microscopic counting. We also show that for the super-radiant scattering, the retarded Green's functions and the corresponding absorption cross sections are in perfect match with CFT prediction.

  13. Rotation Capacity of Bolted Flush End-Plate Stiffened Beam-to-Column Connection

    Science.gov (United States)

    Ostrowski, Krzysztof; Kozłowski, Aleksander

    2017-06-01

    One of the flexibility parameters of semi-rigid joints is rotation capacity. Plastic rotation capacity is especially important in plastic design of framed structures. Current design codes, including Eurocode 3, do not posses procedures enabling designers to obtain value of rotation capacity. In the paper the calculation procedure of the rotation capacity for stiffened bolted flush end-plate beam-to-column connections has been proposed. Theory of experiment design was applied with the use of Hartley's PS/DS-P:Ha3 plan. The analysis was performed with the use of finite element method (ANSYS), based on the numerical experiment plan. The determination of maximal rotation angle was carried out with the use of regression analysis. The main variables analyzed in parametric study were: pitch of the bolt "w" (120-180 mm), the distance between the bolt axis and the beam upper edge cg1 (50-90 mm) and the thickness of the end-plate tp (10-20 mm). Power function was proposed to describe available rotation capacity of the joint. Influence of the particular components on the rotation capacity was also investigated. In the paper a general procedure for determination of rotation capacity was proposed.

  14. Reinforcement of Bolted Timber Joints Using GFRP Sheets in Poplar and Pine Woods

    Directory of Open Access Journals (Sweden)

    Mehrab Madhoushi

    2013-01-01

    Full Text Available Failure in timber structures occurs mainly in crucial points such as joints areas. Therefore, the idea of using composite sheets in timber joints has been intro-duced as a method in order to increase the strength and ductility behaviour of timber joints. This research aims to study the behaviour of bolted joints in poplar and pine woods, which are reinforced by two types of GFRP sheets. A single shear bolted joint consisted of 3 timber members whose length and width were 30 cm in length and 5 cm in width. The thickness of each member was 4 cm for internal part and 2 cm for external part. The employed steel bolt was 10 cm in length and 1 cm in diameter. In this respect, one layer of GFRP sheet was used to be bonded to timber members by using epoxy resin and left between the clamps for 24 hours. They were then kept at room temperature for three weeks. Also the effect of adding a wood veneer on the reinforced joints was investigated. The tensile strength of the reinforced and control samples (un-reinforced joints was measured according to ASTM D5652-92 standard. The results show that the reinforced samples have higher tensile strength compared to that of reinforced joints, although it is not statistically signifcant. Also, two types of sheets infuence the joint behaviour as the reinforced joints display more ductility behaviour.

  15. Mass, Measurement, Materials, and Mathematical Modeling: The Nuts and Bolts of Extrapolation

    Directory of Open Access Journals (Sweden)

    Scott A Sinex

    2011-12-01

    Full Text Available A simple activity is described which is appropriate for any class dealing with measurement. It introduces students to the important scientific process of mathematical modeling and online collaboration. Students, working in groups, determine the mass of a bolt indirectly by extrapolation from massing the bolt with one to five nuts on it and determining the equation of the line; the y-intercept being the mass of the bolt. Students gain experience with using a balance, graphing data, and analyzing results using algebraic skills. They calculate percent error after measuring the bolt’s mass directly and can compare this with the error limits from the least squares fit. Groups enter data into a web-based form and the data is examined by the class using Google Docs in a collaborative manner. After entering data in Google Docs, the students use an interactive Excel spreadsheet to compare their results to the best-fit line obtained by linear regression (pre-built into the spreadsheet for novices. In the spreadsheet, they further explore the model to gain an understanding and examine the influence of scatter (error in the data and material density.

  16. The loosing mechanism of screw bolts on the first wall graphite tiles in EAST

    International Nuclear Information System (INIS)

    Lei Cao; Song Yuntao; Zhou Zibo; Xu Weiwei

    2011-01-01

    The first wall in Experimental Advanced Superconducting Tokamak (EAST) has used many graphite tiles to face the plasma. All graphite ties have been mounted on heat sink using screw bolts which had been preloaded to produce clamp force. The clamp force is very important to keep the graphite tiles on the surface of the heat sink tightly because the heat flux will cross this contacting surface in a small thermal resistor. Without the clamp force the small gap between graphite tiles and heat sink will lead thermal power cannot be carried away by cooling water. The worse is some bolts turned out with the loss of clamp force. From the mathematical models the process of the loss of clamp force has been studied. Research results explain how the different thermal expansion of three members of the screw joint leads to the clamp force decrease to zero under temperature rise and external force and how the stiffness affect the relationship between the clamp force and temperature. The research also gets the critical temperature point that the clamp force can remain above zero. Research results indicated this screw joint is absolute to lose their clamp force during the EAST running so that the bolt joints should be redesign to improve its reliability.

  17. Preload Analysis of Screw Bolt Joints on the First Wall Graphite Tiles in EAST

    International Nuclear Information System (INIS)

    Cao Lei; Song Yuntao

    2012-01-01

    The first wall in the Experimental Advanced Superconducting Tokamak (EAST) used graphite tiles to withstand high thermal energy. The graphite tiles are mounted on the heat sink using screw bolts which have been preloaded to produce a clamp force. The clamp force is very important to keep the graphite tiles tightly on the surface of the heat sink so that the heat flux crosses this contacting surface in a small thermal resistor. Without the clamp force, the small gap between the graphite tiles and the heat sink will make it impossible for thermal power to be carried away by cooling water. Some bolts may even fall off with the loss of clamp force. From the mathematical models, the loss process of the clamp force has been studied. Research results explain how the different thermal expansions of three members of the screw joint makes the clamp force decrease to zero under temperature rise and external force, and how the stiffness affects the relation between the clamp force and temperature. The research also gives the critical temperature at which the clamp force can remain above zero. Analysis results indicate that the current screw joints are almost destined to lose their clamp force during the running time of EAST, so the bolt joints should be redesigned in order to improve its reliability.

  18. Information frictions and monetary policy

    Czech Academy of Sciences Publication Activity Database

    Matějka, Filip

    2012-01-01

    Roč. 6, č. 1 (2012), s. 7-24 ISSN 1802-792X Institutional support: RVO:67985998 Keywords : nominal rigidity * information frictions * monetary economics Subject RIV: AH - Economics http://www.vsfs.cz/periodika/acta-2012-01.pdf

  19. What do Information Frictions Do?

    NARCIS (Netherlands)

    Bhattacharya, J.; Chankraborty, S.

    2003-01-01

    Numerous researchers have incorporated labor or credit market frictions within simple neoclassical models to (i) facilitate quick departures from the Arrow-Debreu world, thereby opening up the role for institutions, (ii) inject some realism into their models, and (iii) explain cross country

  20. Frictional heating of tribological contacts

    NARCIS (Netherlands)

    Bos, Johannes

    1995-01-01

    Wherever friction occurs, mechanical energy is transformed into heat. The tem­ perature rise associated with this heating can have an important influence on the tribological behaviour of the contacting components. Apart from determining per­ formance, thermal phenomena affect reliability and may

  1. Preface: Friction at the nanoscale

    Science.gov (United States)

    Fusc, Claudio; Smith, Roger; Urbakh, Michael; Vanossi, Andrea

    2008-09-01

    Interfacial friction is one of the oldest problems in physics and chemistry, and certainly one of the most important from a practical point of view. Everyday operations on a broad range of scales, from nanometer and up, depend upon the smooth and satisfactory functioning of countless tribological systems. Friction imposes serious constraints and limitations on the performance and lifetime of micro-machines and, undoubtedly, will impose even more severe constraints on the emerging technology of nano-machines. Standard lubrication techniques used for large objects are expected to be less effective in the nano-world. Novel methods for control and manipulation are therefore needed. What has been missing is a molecular level understanding of processes occurring between and close to interacting surfaces to help understand, and later manipulate friction. Friction is intimately related to both adhesion and wear, and all three require an understanding of highly non-equilibrium processes occurring at the molecular level to determine what happens at the macroscopic level. Due to its practical importance and the relevance to basic scientific questions there has been major increase in activity in the study of interfacial friction on the microscopic level during the last decade. Intriguing structural and dynamical features have been observed experimentally. These observations have motivated theoretical efforts, both numerical and analytical. This special issue focusses primarily on discussion of microscopic mechanisms of friction and adhesion at the nanoscale level. The contributions cover many important aspects of frictional behaviour, including the origin of stick-slip motion, the dependence of measured forces on the material properties, effects of thermal fluctuations, surface roughness and instabilities in boundary lubricants on both static and kinetic friction. An important problem that has been raised in this issue, and which has still to be resolved, concerns the

  2. Determining Sincerity of Effort Based on Grip Strength Test in Three Wrist Positions

    Directory of Open Access Journals (Sweden)

    Petcharatana Bhuanantanondh

    2018-03-01

    Full Text Available Background: Several grip strength tests are commonly used for detecting sincerity of effort. However, there is still no widely accepted standardized sincerity of effort test. Therefore, this study aimed to examine whether grip strength test in three wrist positions could distinguish between maximal and submaximal efforts. Methods: Twenty healthy individuals (10 men and 10 women with a mean age of 26.7 ± 3.92 years participated in this study. All participants completed two test conditions (maximal and submaximal efforts in three wrist positions (neutral, flexion, and extension using both hands. Each participant exerted 100% effort in the maximal effort condition and 50% effort in the submaximal effort condition. The participants performed three repetitions of the grip strength test for each session. Results: The results showed that there is a significant main effect of the type of effort (p < 0.001, wrist position (p < 0.001, and hand (p = 0.028. There were also significant types of effort and wrist position interactions (p < 0.001 and effort and hand interactions (p < 0.028. The results also showed that grip strength was highest at the wrist in neutral position in both the maximal and the submaximal effort condition. Grip strength values of the three wrist positions in the maximal effort condition were noticeably greater than those in the submaximal effort condition. Conclusion: The findings of this study suggest that grip strength test in three wrist positions can differentiate a maximal effort from a submaximal effort. Thus, this test could potentially be used to detect sincerity of effort in clinical setting. Keywords: grip strength, maximal effort, sincerity of effort, submaximal effort, wrist position

  3. Clinical effectiveness of grip strength in predicting ambulation of elderly inpatients

    Directory of Open Access Journals (Sweden)

    Beseler MR

    2014-11-01

    Full Text Available MR Beseler,1 C Rubio,1 E Duarte,1 D Hervás,2 MC Guevara,1 M Giner-Pascual,1 E Viosca1 1Physical Medicine and Rehabilitation, La Fe Hospital, Valencia, Spain; 2Statistical Unit, La Fe Hospital, Valencia, Spain Background: Assessing the clinical effectiveness of measuring grip strength as a prognostic tool in recovering ambulation in bed-confined frail elderly patients. Methods: A prospective study was carried out with 50 elderly inpatients (mean age: 81.6 years old. Manual muscle test was used for checking strength of hip flexor muscles, hip abductor muscles and knee extensor muscles. Grip strength was assessed by hydraulic dynamometer. Walking ability was assessed by functional ambulation categories and Functional Classification of Sagunto Hospital Ambulation. Existence of cognitive impairment (Short Portable Mental Status of Pfeiffer and comorbidity (abbreviated Charlson index were considered to be confounding variables. Statistical analysis: Simple comparisons and mixed models of multiple ordinal regression. Results: The sample presented generalized weakness in scapular (mean 4.22 and pelvic (mean 3.82 muscle. Mean hand grip values were similar: 11.98 kg right hand; 11.70 kg left hand. The patients had lost walking ability. After treatment, there was a statistically significant for scapular waist strength (P=0.001, pelvic waist strength (P=0.005 and walking ability (P=0.001. A statistically significant relationship in the regression analysis was found between the grip (right and left hands and walking ability post-treatment (P=0.009; odds ratio 1.14 and P=0.0014 odds ratio 1.113 for each walking scale. The confounding variables showed no statistical significance in the results.Conclusion: Grip strength is associated with walking ability in hospitalized frail elderly. Grip strength assessment by hydraulic dynamometry is useful in patients with poor collaboration. Walking ability training in frail elderly inpatients is useful. Keywords: gait

  4. Age trajectories of grip strength: cross-sectional and longitudinal data among 8,342 Danes aged 46 to 102

    DEFF Research Database (Denmark)

    Frederiksen, Henrik; Hjelmborg, Jacob; Mortensen, Jakob

    2006-01-01

    PURPOSE: The purpose is to study the age trajectory of hand-grip strength after the age of 45 years. METHODS: In this study, we use data from three large nationwide population-based surveys of Danes aged 45 to 102 years with a total of 8342 participants with grip-strength measurements and up to 4...... years of follow-up. Grip strength was measured by using a portable hand dynamometer. RESULTS: Grip strength declines throughout life for both males and females, but among the oldest women, the longitudinal curve reaches a horizontal plateau. The course of the decline is estimated by using full...... with increasing age. Estimates were obtained by using full-information methods from large population-representative studies. Equations of expected grip strength, as well as tables with sex-, age-, and height-stratified reference data, provide an opportunity to include grip-strength measurement in clinical care...

  5. Transcriptomic analysis reveals the roles of gibberellin-regulated genes and transcription factors in regulating bolting in lettuce (Lactuca sativa L.).

    Science.gov (United States)

    Liu, Xueying; Lv, Shanshan; Liu, Ran; Fan, Shuangxi; Liu, Chaojie; Liu, Renyi; Han, Yingyan

    2018-01-01

    A cool temperature is preferred for lettuce cultivation, as high temperatures cause premature bolting. Accordingly, exploring the mechanism of bolting and preventing premature bolting is important for agriculture. To explore this relationship in depth, morphological, physiological, and transcriptomic analyses of the bolting-sensitive line S39 at the five-leaf stage grown at 37°C were performed in the present study. Based on paraffin section results, we observed that S39 began bolting on the seventh day at 37°C. During bolting in the heat-treated plants, GA3 and GA4 levels in leaves and the indoleacetic acid (IAA) level in the stem reached a maximum on the sixth day, and these high contents were maintained. Additionally, bolting begins in the fifth day after GA3 treatment in S39 plants, GA3 and GA4 increased and then decreased, reaching a maximum on the fourth day in leaves. Similarly, IAA contents reached a maximum in the stem on the fifth day. No bolting was observed in the control group grown at 25°C, and significant changes were not observed in GA3 and GA4 levels in the controls during the observation period. RNA-sequencing data implicated transcription factors (TFs) in regulating bolting in lettuce, suggesting that the high GA contents in the leaves and IAA in the stem promote bolting. TFs possibly modulate the expression of related genes, such as those encoding hormones, potentially regulating bolting in lettuce. Compared to the control group, 258 TFs were identified in the stem of the treatment group, among which 98 and 156 were differentially up- and down-regulated, respectively; in leaves, 202 and 115 TFs were differentially up- and down-regulated, respectively. Significant changes in the treated group were observed for C2H2 zinc finger, AP2-EREBP, and WRKY families, indicating that these TFs may play important roles in regulating bolting.

  6. Large-scale GWAS identifies multiple loci for hand grip strength providing biological insights into muscular fitness

    DEFF Research Database (Denmark)

    Willems, Sara M; Wright, Daniel J; Day, Felix R

    2017-01-01

    ,180 individuals and identify 16 loci associated with grip strength (Pmaintenance and signal transduction (PEX14, TGFA, SYT1), or monogenic syndromes...... with involvement of psychomotor impairment (PEX14, LRPPRC and KANSL1). Mendelian randomization analyses are consistent with a causal effect of higher genetically predicted grip strength on lower fracture risk. In conclusion, our findings provide new biological insight into the mechanistic underpinnings of grip...

  7. Friction, Free Axes of Rotation and Entropy

    Directory of Open Access Journals (Sweden)

    Alexander Kazachkov

    2017-03-01

    Full Text Available Friction forces acting on rotators may promote their alignment and therefore eliminate degrees of freedom in their movement. The alignment of rotators by friction force was shown by experiments performed with different spinners, demonstrating how friction generates negentropy in a system of rotators. A gas of rigid rotators influenced by friction force is considered. The orientational negentropy generated by a friction force was estimated with the Sackur-Tetrode equation. The minimal change in total entropy of a system of rotators, corresponding to their eventual alignment, decreases with temperature. The reported effect may be of primary importance for the phase equilibrium and motion of ubiquitous colloidal and granular systems.

  8. Deep transverse friction massage for treating lateral elbow or lateral knee tendinitis.

    Science.gov (United States)

    Loew, Laurianne M; Brosseau, Lucie; Tugwell, Peter; Wells, George A; Welch, Vivian; Shea, Beverley; Poitras, Stephane; De Angelis, Gino; Rahman, Prinon

    2014-11-08

    mean difference (MD) for continuous outcomes and risk ratio (RR)for dichotomous outcomes with 95% confidence intervals (CIs).Main results Two RCTs (no new additional studies in this update) with 57 participants met the inclusion criteria. These studies demonstrated high risk of performance and detection bias, and the risk of selection, attrition, and reporting bias was unclear.The first study included 40 participants with lateral elbow tendinitis and compared (1) deep transverse friction massage combined with therapeutic ultrasound and placebo ointment (n = 11) versus therapeutic ultrasound and placebo ointment only (n = 9) and (2)deep transverse friction massage combined with phonophoresis (n = 10) versus phonophoresis only (n = 10). No statistically significant differences were reported within five weeks for mean change in pain on a 0 to 100 visual analog scale (VAS) (MD -6.60, 95%CI -28.60 to 15.40; 7% absolute improvement), grip strength measured in kilograms of force (MD 0.10, 95% CI -0.16 to 0.36) and function ona 0 to 100 VAS (MD -1.80, 95% CI -0.18.64 to 15.04; 2% improvement), pain-free function index measured as the number of painfree items (MD 1.10, 95% CI -1.00 to 3.20) and functional status (RR 3.3, 95% CI 0.4 to 24.3) for deep transverse friction massage,and therapeutic ultrasound and placebo ointment compared with therapeutic ultrasound and placebo ointment only. Likewise for deep transverse friction massage and phonophoresis compared with phonophoresis alone, no statistically significant differences were found for pain (MD -1.2, 95% CI -20.24 to 17.84; 1% improvement), grip strength (MD -0.20, 95% CI -0.46 to 0.06) and function (MD3.70, 95% CI -14.13 to 21.53; 4% improvement). In addition, the GRADE (Grades of Recommendation, Assessment, Development and Evaluation) approach was used to evaluate the quality of evidence for the pain outcome, which received a score of "very low".Pain relief of 30% or greater, quality of life, patient global assessment

  9. Relationship between grip, pinch strengths and anthropometric variables, types of pitch throwing among Japanese high school baseball pitchers.

    Science.gov (United States)

    Tajika, Tsuyoshi; Kobayashi, Tsutomu; Yamamoto, Atsushi; Shitara, Hitoshi; Ichinose, Tsuyoshi; Shimoyama, Daisuke; Okura, Chisa; Kanazawa, Saeko; Nagai, Ayako; Takagishi, Kenji

    2015-03-01

    Grip and pinch strength are crucially important attributes and standard parameters related to the functional integrity of the hand. It seems significant to investigate normative data for grip and pinch strength of baseball players to evaluate their performance and condition. Nevertheless, few reports have explained the association between grip and pinch strength and anthropometric variables and types of pitch throwing for baseball pitchers. The aim of this study was to measure and evaluate clinical normative data for grip and tip, key, palmar pinch strength and to assess the relationship between these data and anthropometric variables and types of pitch throwing among Japanese high-school baseball pitchers. One hundred-thirty three healthy high school baseball pitchers were examined and had completed a self-administered questionnaire including items related to age, hand dominance, throwing ratio of type of pitch. A digital dynamometer was used to measure grip strength and a pinch gauge to measure tip, key and palmer pinch in both dominant and nondominant side. Body composition was measured by the multi frequency segmental body composition analyzer. Grip strength and tip and palmer pinch strength in dominant side were statistically greater than them in nondominant side (P strength and height (r = 0.33, P strength were predictors of grip strength in dominant side. No statistical significant correlations were found between the throwing ratio of types of pitches thrown and grip strength and tip, key, palmar pinch strength. Our result provides normative values and evidences for grip and pinch strengths in high school baseball pitchers.

  10. Sex Differences in Fear of Falling among Older Adults with Low Grip Strength.

    Science.gov (United States)

    Lim, Eunju

    2016-05-01

    Fear of falling is not only a risk factor for falls, but it is also an important clinical predictor of functional decline in older adults. This study identified sex differences in fear of falling and related factors in older adults with low grip strength. The data of 902 older adults from the 2012 Korean National Survey, conducted as a research project by the Korea Employment Information Service, were analyzed. Grip strength, activities of daily living, cognitive function, depressive symptoms, and fear of falling were assessed. Multiple regression analysis was performed by a simultaneous data entry method. Fear of falling was greater in older women with low grip strength than in their male equivalents (Pfall experience within the previous 2 yr, activities of daily living, and depressive symptoms collectively accounted for 15.3% (Pfall experience within the previous 2 yr, grip strength, activities of daily living, and depressive symptoms collectively accounted for 13.4% (Pfalling differ between older men and women with low grip strength. Therefore, sex differences must be considered when developing intervention strategies for reducing fear of falling in this demographic.

  11. E-GRIP: A Highly Elliptical Orbit Satellite Mission for Co-location in Space

    Science.gov (United States)

    Männel, Benjamin; Rothacher, Markus; Jetzer, Philippe; Lecomte, Steve; Rochat, Pascal

    2016-12-01

    The Einstein Gravitational Red-shift Probe (E-GRIP) will be a new satellite mission allowing detailed studies for relativistic and geodetic purposes. The scientific objectives of E-GRIP are the measurement of the space-time curvature around the Earth, multiple tests of general relativity, and special geodetic applications. E-GRIP will fly in a highly eccentric orbit (e>0.6, apogee > 35000 km) and will carry a narrow- and a wide-angle microwave link (at both X- and K-band), two GNSS antennas, SLR retro-reflectors, a photon counter unit, and a space hydrogen maser. Consequently, E-GRIP could act as a co-location satellite with suitable observation conditions for VLBI. Beyond a mission overview, we provide results from extended VLBI simulations concerning link budget, visibilities, and achievable station coordinate results. In addition, we present also some basic considerations concerning the feasibility of co-located GNSS and SLR observations for E-GRIP's highly elliptical orbit.

  12. Probabilistic information on object weight shapes force dynamics in a grip-lift task.

    Science.gov (United States)

    Trampenau, Leif; Kuhtz-Buschbeck, Johann P; van Eimeren, Thilo

    2015-06-01

    Advance information, such as object weight, size and texture, modifies predictive scaling of grip forces in a grip-lift task. Here, we examined the influence of probabilistic advance information about object weight. Fifteen healthy volunteers repeatedly grasped and lifted an object equipped with a force transducer between their thumb and index finger. Three clearly distinguishable object weights were used. Prior to each lift, the probabilities for the three object weights were given by a visual cue. We examined the effect of probabilistic pre-cues on grip and lift force dynamics. We expected predictive scaling of grip force parameters to follow predicted values calculated according to probabilistic contingencies of the cues. We observed that probabilistic cues systematically influenced peak grip and load force rates, as an index of predictive motor scaling. However, the effects of probabilistic cues on force rates were nonlinear, and anticipatory adaptations of the motor output generally seemed to overestimate high probabilities and underestimate low probabilities. These findings support the suggestion that anticipatory adaptations and force scaling of the motor system can integrate probabilistic information. However, probabilistic information seems to influence motor programs in a nonlinear fashion.

  13. Jamar hand-held grip dynamometry in chronic inflammatory demyelinating polyneuropathy.

    Science.gov (United States)

    Rajabally, Yusuf A; Narasimhan, Manisha

    2013-02-15

    Few studies have evaluated the functional and electrophysiological correlates of hand-held grip dynamometry in neuromuscular disease. The practical value of normative values remains uncertain in clinical practice. We aimed to ascertain the value, clinical and electrophysiological correlates, as well as utility of normative values for grip dynamometry, in a cohort of subjects with chronic inflammatory demyelinating polyneuropathy (CIDP). We performed a cross-sectional study of 31 prospectively recruited subjects with CIDP, using Jamar hand-held grip dynamometry, conventional clinical assessments and electrophysiology. Grip dynamometry correlated highly with motor, sensory and functional scores in the upper limbs as well as with global function. There were significant correlations with summated median/ulnar, and ulnar compound muscle action potentials. Patients' readings were significantly lower than median normative values but comparable to fifth percentile normative figures. Jamar grip dynamometry is a reliable measure of global neurological status in patients with CIDP, not limited to upper limb or exclusively motor function. At optimum level of function, CIDP patients had comparable dynamometry recordings to fifth percentile normative values, which may represent a realistic aim for treated subjects with the disorder, with currently available therapies. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

  14. Evaluation of Interlaminar Stresses in Composite Laminates with a Bolt-Filled Hole Using a Linear Elastic Traction-Separation Description

    Directory of Open Access Journals (Sweden)

    Yong Cao

    2017-01-01

    Full Text Available Determination of the local interlaminar stress distribution in a laminate with a bolt-filled hole is helpful for optimal bolted joint design, due to the three-dimensional (3D nature of the stress field near the bolt hole. A new interlaminar stress distribution phenomenon induced by the bolt-head and clamp-up load, which occurs in a filled-hole composite laminate, is investigated. In order to efficiently evaluate interlaminar stresses under the complex boundary condition, a calculation strategy that using zero-thickness cohesive interface element is presented and validated. The interface element is based on a linear elastic traction-separation description. It is found that the interlaminar stress concentrations occur at the hole edge, as well as the interior of the laminate near the periphery of the bolt head. In addition, the interlaminar stresses near the periphery of the bolt head increased with an increase in the clamp-up load, and the interlaminar normal and shear stresses are not at the same circular position. Therefore, the clamp-up load cannot improve the interlaminar stress distribution in the laminate near the periphery of the bolt head, although it can reduce the magnitude of the interlaminar shear stress at the hole edge. Thus, the interlaminar stress distribution phenomena may lead to delamination initiation in the laminate near the periphery of the bolt head, and should be considered in composite bolted joint design.

  15. KINEMATICS FRICTION PAIR FOR EXAMPLE NEEDLE BEARINGS

    Directory of Open Access Journals (Sweden)

    Jerzy NACHIMOWICZ

    2014-06-01

    Full Text Available The present study concerns certain phenomena that take place in the needle roller bearing. The friction that generates the anti-torque of a friction pair is the major factor that influences the needle bearing’s wear. In the needle bearing there occur two predominant types of friction: the rolling friction and the sliding friction, and both are subject to examination. The study presents recordings and analysis of the movements of all needle bearing’s rolling elements. The examination was carried out on a special examination stand that precisely emulates the real conditions of the needle bearing’s work. Carefully prepared examination methods enable recording and analyzing frictions in the bearing, estimating a sphere within which the load is shifted, and calculating the coefficient of friction.

  16. Identification of flowering-related genes responsible for differences in bolting time between two radish inbred lines

    Directory of Open Access Journals (Sweden)

    Hye Sun Cho

    2016-12-01

    Full Text Available Late bolting after cold exposure is an economically important characteristic of radish (Raphanus sativus L., an important Brassicaceae root vegetable crop. However, little information is available regarding the genes and pathways that govern flowering time in this species. We performed high-throughput RNA sequencing analysis to elucidate the molecular mechanisms that determine the differences in flowering times between two radish lines, NH-JS1 (late bolting and NH-JS2 (early bolting. In total, 71,188 unigenes were identified by reference-guided assembly, of which 309, 788, and 980 genes were differentially expressed between the two inbred lines after 0, 15, and 35 days of vernalization, respectively. Among these genes, 218 homologs of Arabidopsis flowering-time (Ft genes were identified in the radish, and 49 of these genes were differentially expressed between the two radish lines in the presence or absence of vernalization treatment. Most of the Ft genes up-regulated in NH-JS1 vs NH-JS2 were repressors of flowering, such as RsFLC, consistent with the late-bolting phenotype of NH-JS1. Although the functions of genes down-regulated in NH-JS1 were less consistent with late-bolting characteristics than the up-regulated Ft genes, several Ft enhancer genes, including RsSOC1, a key floral integrator, showed an appropriate expression to the late-bolting phenotype. In addition, the patterns of gene expression related to the vernalization pathway closely corresponded with the different bolting times of the two inbred lines. These results suggest that the vernalization pathway is conserved between radish and Arabidopsis.

  17. Internal friction in irradiated textolite

    International Nuclear Information System (INIS)

    Zajkin, Yu.A.; Kozhamkulov, B.A.; Koztaeva, U.P.

    1996-01-01

    Structural relaxation in irradiated textolite of ST and ST-EhTF trade marks presenting pressed material got by method of impregnation of fibreglass by phenole and epoxytriphenole binders relatively. Measuring of temperature dependences of internal friction (TDIF) is carried out in torsional pendulum at oscillation frequency 0.6-1.0 Hz before and after irradiation by stopped gamma-quanta with energy 3 MeV on electron accelerator EhLU-4. α and β peaks, related with segments motion in base and side chains of macromolecular have being observed on TDIF of all textolite. Growth of peaks height after irradiation evident about increase of segments mobility in base chain and about de-freezing of segments in side chains and it could be considered as qualitative measure of radiation destruction rate. Comparison of temperature dependences of internal friction indicates on higher radiation stability of textolite of ST-EhTF trade mark

  18. Friction and wear in sodium

    International Nuclear Information System (INIS)

    Hoffman, N.J.; Droher, J.J.

    1973-01-01

    In the design of a safe and reliable sodium-cooled reactor one of the more important problem areas is that of friction and wear of components immersed in liquid sodium or exposed to sodium vapor. Sodium coolant at elevated temperatures may severely affect most oxide-bearing surface layers which provide corrosion resistance and, to some extent, lubrication and surface hardness. Consequently, accelerated deterioration may be experienced on engaged-motion contact surfaces, which could result in unexpected reactor shutdown from component malfunction or failure due to galling and seizure. An overall view of the friction and wear phenomena encountered during oscillatory rubbing of surfaces in high-temperature, liquid-sodium environments is presented. Specific data generated at the Liquid Metal Engineering Center (LMEC) on this subject is also presented. (U.S.)

  19. An investigation of maximal hand grip strength related to body mass index in healthy Czech children

    Directory of Open Access Journals (Sweden)

    Martin Šteffl

    2016-12-01

    Full Text Available Hand grip strength is one of the most important markers in muscle strength assessment for many reasons. However, its maximal value in kilograms is highly dependent on body size, which may misrepresent results, especially among children. Therefore, correction by body mass index (BMI can be used as a suitable approach for its objectification. The aims of this study were to create reference values for the grip to BMI ratio and for hand grip strength for children in the Czech Republic. 554 children of both genders, aged from 4 to 14 years, were included in the current study. Reference values were approximated by Tukey’s Hinges percentiles calculation method. The percentile charts were created using the Lambda-Mu-Sigma (LMS method.

  20. Two cases of firearm grip impressions on the hands of suicide victims.

    Science.gov (United States)

    Poulos, Christopher K; Peterson, Brian L

    2012-03-01

    Many factors are used to help distinguish firearm suicides from homicides and accidents, including range of fire, location of entrance defects, wound path trajectory, backspatter (blowback), and gunshot residue. Specifically, authors have discussed examination of the hands for backspatter, gunshot residue, cylinder gap effects, iron staining, and trauma as means of supporting a person having held a firearm while committing suicide. Here, we discuss 2 cases where suicidal gunshot wounds were accompanied by unique firearm grip impressions on the hands of the decedents. In 1 case, a "negative"[ impression of a grip pattern was left in a decedent's hand and in another case a grip pattern was left on the decedent's hand in dried blood. Such impressions can be used to provide support for establishing suicide as the manner of death.

  1. Grip force is part of the semantic representation of manual action verbs.

    Science.gov (United States)

    Frak, Victor; Nazir, Tatjana; Goyette, Michel; Cohen, Henri; Jeannerod, Marc

    2010-03-16

    Motor actions and action verbs activate similar cortical brain regions. A functional interference can be taken as evidence that there is a parallel treatment of these two types of information and would argue for the biological grounding of language in action. A novel approach examining the relationship between language and grip force is presented. With eyes closed and arm extended, subjects listened to words relating (verbs) or not relating (nouns) to a manual action while holding a cylinder with an integrated force sensor. There was a change in grip force when subjects heard verbs that related to manual action. Grip force increased from about 100 ms following the verb presentation, peaked at 380 ms and fell abruptly after 400 ms, signalling a possible inhibition of the motor simulation evoked by these words. These observations reveal the intimate relationship that exists between language and grasp and show that it is possible to elucidate online new aspects of sensorimotor interaction.

  2. Grip force is part of the semantic representation of manual action verbs.

    Directory of Open Access Journals (Sweden)

    Victor Frak

    Full Text Available Motor actions and action verbs activate similar cortical brain regions. A functional interference can be taken as evidence that there is a parallel treatment of these two types of information and would argue for the biological grounding of language in action. A novel approach examining the relationship between language and grip force is presented. With eyes closed and arm extended, subjects listened to words relating (verbs or not relating (nouns to a manual action while holding a cylinder with an integrated force sensor. There was a change in grip force when subjects heard verbs that related to manual action. Grip force increased from about 100 ms following the verb presentation, peaked at 380 ms and fell abruptly after 400 ms, signalling a possible inhibition of the motor simulation evoked by these words. These observations reveal the intimate relationship that exists between language and grasp and show that it is possible to elucidate online new aspects of sensorimotor interaction.

  3. Internal friction in uranium dioxide

    International Nuclear Information System (INIS)

    Paulin Filho, Pedro Iris

    1979-01-01

    The uranium dioxide inelastic properties were studied measuring internal friction at low frequencies (of the order of 1 Hz). The work was developed in the 160 to 400 deg C temperature range. The effect of stoichiometry variation was studied oxidizing the sample with consequent change of the defect structure originally present in the non-stoichiometric uranium dioxide. The presence of a wide and irregular peak due to oxidation was observed at low temperatures. Activation energy calculations indicated the occurrence of various relaxation processes and assuming the existence of a peak between - 80 and - 70 deg C , the absolute value obtained for the activation energy (0,54 eV) is consistent with the observed values determined at medium and high frequencies for the stress induced reorientation of defects. The microstructure effect on the inelastic properties was studied for stoichiometric uranium dioxide, by varying grain size and porosity. These parameters have influence on the high temperature measurements of internal friction. The internal friction variation for temperatures higher than 340 deg C is thought to be due to grain boundary relaxation phenomena. (author)

  4. Maximal intermittent handgrip strategy: design and evaluation of an exercise protocol and a grip tool.

    Science.gov (United States)

    Bentley, Danielle Christine; Thomas, Scott Gordon

    2016-01-01

    Handgrip (HG) exercise has been prescribed as a lifestyle intervention to successfully reduce resting blood pressure (BP) among heterogeneous groups of participants. Current HG protocols have limited accessibility due to complicated exercise prescriptions and sophisticated required equipment. Therefore, this research describes the design and evaluation of the maximal intermittent (MINT) HG exercise strategy, consisting of both a novel exercise protocol (32×5 seconds maximal grip squeezes separated by 5 seconds of rest between sets) and an original grip tool. This research was a multistep progressive design that included 51 postmenopausal women as participants in three separate research studies. Part 1 of this research focuses on the MINT exercise protocol. A literature-informed rationale for the design of the protocol is described. This includes exercise intensity, work-to-rest ratio, and total exercise duration with reference to the unique physiology (mechanoreflex and metaboreflex) of postmenopausal women. Subsequent experimental analyses of acute responses to the MINT protocol revealed that women produced 50% of their maximum grip force with moderate cardiovascular responses (increases of systolic BP: 41.6 mmHg, diastolic BP: 20.1 mmHg, heart rate: 35.1 bpm) that remained far below the thresholds of concern identified by the American College of Sports Medicine. Part 2 of this research describes the creation of a novel grip tool, beginning with a mixed-methods assessment of participant opinions regarding two distinct in-laboratory grip tools, leading to the creation of four prototype MINT tools. Structured focus groups revealed a strong preference for MINT prototype 1 for all tool design features, including color, shape, size, and foam grip. Collectively, the result of this multistep research is a novel HG exercise strategy with enhanced accessibility by being easy to understand and simple to execute. The long-term training effectiveness of MINT as an exercise

  5. Effect of Low-Level Laser Therapy and Strength Training Protocol on Hand Grip by Dynamometry.

    Science.gov (United States)

    Barbosa, Rafael; Marcolino, Alexandre; Souza, Vitor; Bertolino, Guilherme; Fonseca, Marisa; Guirro, Rinaldo

    2017-01-01

    Introduction: The purpose of this study was to investigate the effect of low-level laser therapy (LLLT) - 660 nm and 904 nm - before grip strength protocol in healthy subjects. Methods: The study included 45 healthy volunteers with an average age of 22.7 (±1.4) years, subdivided into the following groups, control group: grip strength training associated with placebo LLLT; 660 nm group: LLLT (660 nm, 20 J/cm 2 , power of 30 mW, and beam area of 0.06 cm 2 , continuous, energy 1.2 J, and exposure time 40 seconds per point) before grip strength training and 904 nm group: LLLT (904 nm, 10 J/cm 2 , peak power of 70 W and 0.13 cm 2 beam area, with pulsed beam 9.500 Hz and 30 seconds of exposure time per point and emitted energy 1.2 J) before grip strength training. The LLLT was timed to contact 10 points located in the region of the superficial and deep flexor muscles of the fingers, with a total energy of 12.0 J per session. For the strength training protocol, the volunteer exercised their fingers with the dominant hand on a small table, elbow flexed at 90°, forearm in neutral, using a light extension handle. The Oxford protocol was performed during four weeks. The grip strength was assessed using a dynamometer (Jamar™). The data were evaluated by the analysis of variance (ANOVA) statistical method. Results: In the comparison of intragroup evaluation, only the 904 nm group showed a difference compared to the baseline assessment after 4 weeks ( P < 0.05), in the final intergroup evaluation, a difference was observed in the comparison between the control and 904 nm groups Conclusion: In conclusion, LLLT (904 nm) applied before resistance training was effective in gaining grip strength when compared to LLLT (660 nm) and isolated strength training after 4 weeks.

  6. Friction of elastomer-on-glass system and direct observation of its frictional interface

    International Nuclear Information System (INIS)

    Okamoto, Yoshihiro; Nishio, Kazuyuki; Sugiura, Jun-ichi; Hirano, Motohisa; Nitta, Takahiro

    2007-01-01

    We performed a study on the static friction of PDMS elastomers with well-defined surface topography sliding over glass. An experimental setup for simultaneous measurements of friction force and direct observations of frictional interface has been developed. The static friction force was nearly proportional to normal load. The static friction force was independent of stick time. The simultaneous measurements revealed that the static friction force was proportional to the total area of contact. The coefficient was nearly independent of the surface topography of PDMS elastomers

  7. Inflorescence Development and the Role of LsFT in Regulating Bolting in Lettuce (Lactuca sativa L.

    Directory of Open Access Journals (Sweden)

    Zijing Chen

    2018-01-01

    Full Text Available Lettuce (Lactuca sativa L. is one of the most important leafy vegetable that is consumed during its vegetative growth. The transition from vegetative to reproductive growth is induced by high temperature, which has significant economic effect on lettuce production. However, the progression of floral transition and the molecular regulation of bolting are largely unknown. Here we morphologically characterized the inflorescence development and functionally analyzed the FLOWERING LOCUS T (LsFT gene during bolting regulation in lettuce. We described the eight developmental stages during floral transition process. The expression of LsFT was negatively correlated with bolting in different lettuce varieties, and was promoted by heat treatment. Overexpression of LsFT could recover the late-flowering phenotype of ft-2 mutant. Knockdown of LsFT by RNA interference dramatically delayed bolting in lettuce, and failed to respond to high temperature. Therefore, this study dissects the process of inflorescence development and characterizes the role of LsFT in bolting regulation in lettuce.

  8. Inflorescence Development and the Role of LsFT in Regulating Bolting in Lettuce (Lactuca sativa L.)

    Science.gov (United States)

    Chen, Zijing; Han, Yingyan; Ning, Kang; Ding, Yunyu; Zhao, Wensheng; Yan, Shuangshuang; Luo, Chen; Jiang, Xiaotang; Ge, Danfeng; Liu, Renyi; Wang, Qian; Zhang, Xiaolan

    2018-01-01

    Lettuce (Lactuca sativa L.) is one of the most important leafy vegetable that is consumed during its vegetative growth. The transition from vegetative to reproductive growth is induced by high temperature, which has significant economic effect on lettuce production. However, the progression of floral transition and the molecular regulation of bolting are largely unknown. Here we morphologically characterized the inflorescence development and functionally analyzed the FLOWERING LOCUS T (LsFT) gene during bolting regulation in lettuce. We described the eight developmental stages during floral transition process. The expression of LsFT was negatively correlated with bolting in different lettuce varieties, and was promoted by heat treatment. Overexpression of LsFT could recover the late-flowering phenotype of ft-2 mutant. Knockdown of LsFT by RNA interference dramatically delayed bolting in lettuce, and failed to respond to high temperature. Therefore, this study dissects the process of inflorescence development and characterizes the role of LsFT in bolting regulation in lettuce. PMID:29403510

  9. Nano-friction behavior of phosphorene

    Science.gov (United States)

    Bai, Lichun; Liu, Bo; Srikanth, Narasimalu; Tian, Yu; Zhou, Kun

    2017-09-01

    Nano-friction of phosphorene plays a significant role in affecting the controllability and efficiency of applying strain engineering to tune its properties. So far, the friction behavior of phosphorene has not been studied. This work studies the friction of single-layer and bilayer phosphorene on an amorphous silicon substrate by sliding a rigid tip. For the single-layer phosphorene, it is found that its friction is highly anisotropic, i.e. the friction is larger along the armchair direction than that along the zigzag direction. Moreover, pre-strain of the phosphorene also exhibits anisotropic effects. The friction increases with the pre-strain along the zigzag direction, but decreases with that along the armchair direction. Furthermore, the strong adhesion between the phosphorene and its substrate increases the friction between the phosphorene and the tip. For bilayer phosphorene, its friction highly depends on its stacking mode, which determines the contact interface with a commensurate or incommensurate pattern. This friction behavior is quite unique and greatly differs from that of graphene and molybdenum disulfide. Detailed analysis reveals that this behavior results from the combination effect of the friction contact area, the potential-energy profile of phosphorene, and its unique elongation.

  10. Kinetic Friction of Sport Fabrics on Snow

    Directory of Open Access Journals (Sweden)

    Werner Nachbauer

    2016-03-01

    Full Text Available After falls, skiers or snowboarders often slide on the slope and may collide with obstacles. Thus, the skier’s friction on snow is an important factor to reduce incidence and severity of impact injuries. The purpose of this study was to measure snow friction of different fabrics of ski garments with respect to roughness, speed, and contact pressure. Three types of fabrics were investigated: a commercially available ski overall, a smooth downhill racing suit, and a dimpled downhill racing suit. Friction was measured for fabrics taped on a short ski using a linear tribometer. The fabrics’ roughness was determined by focus variation microscopy. Friction coefficients were between 0.19 and 0.48. Roughness, friction coefficient, and friction force were highest for the dimpled race suit. The friction force of the fabrics was higher for the higher contact pressure than for the lower one at all speeds. It was concluded that the main friction mechanism for the fabrics was dry friction. Only the fabric with the roughest surface showed friction coefficients, which were high enough to sufficiently decelerate a sliding skier on beginner and intermediate slopes.

  11. Direct observation of salts as micro-inclusions in the Greenland GRIP ice core

    DEFF Research Database (Denmark)

    Dahl-Jensen, Dorthe; Sakurai, Toshimitsu; Iizuka, Yoshinori

    2009-01-01

    We provide the first direct evidence that a number of water-soluble compounds, in particular calcium sulfate (CaSO4·2H2O) and calcium carbonate (CaCO3), are present as solid, micron-sized inclusions within the Greenland GRIP ice core. The compounds are detected by two independent methods: micro...... distributions of the micro-inclusions. These results suggest that water-soluble aerosols in the GRIP ice core are dependable proxies for past atmospheric conditions. Udgivelsesdato: December...

  12. Probability of detection for bolt hole eddy current in extracted from service aircraft wing structures

    Science.gov (United States)

    Underhill, P. R.; Uemura, C.; Krause, T. W.

    2018-04-01

    Fatigue cracks are prone to develop around fasteners found in multi-layer aluminum structures on aging aircraft. Bolt hole eddy current (BHEC) is used for detection of cracks from within bolt holes after fastener removal. In support of qualification towards a target a90/95 (detect 90% of cracks of depth a, 95% of the time) of 0.76 mm (0.030"), a preliminary probability of detection (POD) study was performed to identify those parameters whose variation may keep a bolt hole inspection from attaining its goal. Parameters that were examined included variability in lift-off due to probe type, out-of-round holes, holes with diameters too large to permit surface-contact of the probe and mechanical damage to the holes, including burrs. The study examined the POD for BHEC of corner cracks in unfinished fastener holes extracted from service material. 68 EDM notches were introduced into two specimens of a horizontal stabilizer from a CC-130 Hercules aircraft. The fastener holes were inspected in the unfinished state, simulating potential inspection conditions, by 7 certified inspectors using a manual BHEC setup with an impedance plane display and also with one inspection conducted utilizing a BHEC automated C-Scan apparatus. While the standard detection limit of 1.27 mm (0.050") was achieved, given the a90/95 of 0.97 mm (0.039"), the target 0.76 mm (0.030") was not achieved. The work highlighted a number of areas where there was insufficient information to complete the qualification. Consequently, a number of recommendations were made. These included; development of a specification for minimum probe requirements; criteria for condition of the hole to be inspected, including out-of-roundness and presence of corrosion pits; statement of range of hole sizes; inspection frequency and data display for analysis.

  13. Large-scale GWAS identifies multiple loci for hand grip strength providing biological insights into muscular fitness

    DEFF Research Database (Denmark)

    Willems, Sara M; Wright, Daniel J.; Day, Felix R

    2017-01-01

    with involvement of psychomotor impairment (PEX14, LRPPRC and KANSL1). Mendelian randomization analyses are consistent with a causal effect of higher genetically predicted grip strength on lower fracture risk. In conclusion, our findings provide new biological insight into the mechanistic underpinnings of grip...

  14. Grip strength and lower limb extension power in 19-72-year-old Danish men and women

    DEFF Research Database (Denmark)

    Aadahl, Mette; Beyer, Nina; Linneberg, Allan

    2011-01-01

    To assess muscular fitness by hand grip strength (HGS) and lower limb extension power (LEP) and to explore associations with age, leisure time physical activity (LTPA) and body composition.......To assess muscular fitness by hand grip strength (HGS) and lower limb extension power (LEP) and to explore associations with age, leisure time physical activity (LTPA) and body composition....

  15. Large-scale GWAS identifies multiple loci for hand grip strength providing biological insights into muscular fitness

    NARCIS (Netherlands)

    Willems, Sara M.; Wright, D.J.; Day, Felix R.; Trajanoska, Katerina; Joshi, P.K.; Morris, John A.; Matteini, Amy M.; Garton, Fleur C.; Grarup, Niels; Oskolkov, Nikolay; Thalamuthu, Anbupalam; Mangino, Massimo; Liu, Jun; Demirkan, Ayse; Lek, Monkol; Xu, Liwen; Wang, Guan; Oldmeadow, Christopher; Gaulton, Kyle J.; Lotta, Luca A.; Miyamoto-Mikami, Eri; Rivas, Manuel A.; White, Tom; Loh, Po Ru; Aadahl, Mette; Amin, Najaf; Attia, John R.; Austin, Krista; Benyamin, Beben; Brage, Søren; Cheng, Yu Ching; Ciȩszczyk, Paweł; Derave, Wim; Eriksson, Karl Fredrik; Eynon, Nir; Linneberg, Allan; Lucia, Alejandro; Massidda, Myosotis; Mitchell, Braxton D.; Miyachi, Motohiko; Murakami, Haruka; Padmanabhan, Sandosh; Pandey, Ashutosh; Papadimitriou, Ioannis; Rajpal, Deepak K.; Sale, Craig; Schnurr, Theresia M.; Sessa, Francesco; Shrine, Nick; Tobin, Martin D.; Varley, Ian; Wain, Louise V.; Wray, Naomi R.; Lindgren, Cecilia M.; MacArthur, Daniel G.; Waterworth, Dawn M.; McCarthy, Mark I.; Pedersen, Oluf; Khaw, Kay Tee; Kiel, Douglas P.; Pitsiladis, Yannis; Fuku, Noriyuki; Franks, Paul W.; North, Kathryn N.; Duijn, Van C.M.; Mather, Karen A.; Hansen, Torben; Hansson, Ola; Spector, Tim D.; Murabito, Joanne M.; Richards, J.B.; Rivadeneira, Fernando; Langenberg, Claudia; Perry, John R.B.; Wareham, Nick J.; Scott, Robert A.; Oei, Ling; Zheng, Hou Feng; Forgetta, Vincenzo; Leong, Aaron; Ahmad, Omar S.; Laurin, Charles; Mokry, Lauren E.; Ross, Stephanie; Elks, Cathy E.; Bowden, Jack; Warrington, Nicole M.; Murray, Anna; Ruth, Katherine S.; Tsilidis, Konstantinos K.; Medina-Gómez, Carolina; Estrada, Karol; Bis, Joshua C.; Chasman, Daniel I.; Demissie, Serkalem; Enneman, Anke W.; Hsu, Yi Hsiang; Ingvarsson, Thorvaldur; Kähönen, Mika; Kammerer, Candace; Lacroix, Andrea Z.; Li, Guo; Liu, Ching Ti; Liu, Yongmei; Lorentzon, Mattias; Mägi, Reedik; Mihailov, Evelin; Milani, Lili; Moayyeri, Alireza; Nielson, Carrie M.; Sham, Pack Chung; Siggeirsdotir, Kristin; Sigurdsson, Gunnar; Stefansson, Kari; Trompet, Stella; Thorleifsson, Gudmar; Vandenput, Liesbeth; Velde, Van Der Nathalie; Viikari, Jorma; Xiao, Su Mei; Zhao, Jing Hua; Evans, Daniel S.; Cummings, Steven R.; Cauley, Jane; Duncan, Emma L.; Groot, De Lisette C.P.G.M.; Esko, Tonu; Gudnason, Vilmundar; Harris, Tamara B.; Jackson, Rebecca D.; Jukema, J.W.; Ikram, Arfan M.A.; Karasik, David; Kaptoge, Stephen; Kung, Annie Wai Chee; Lehtimäki, Terho; Lyytikäinen, Leo Pekka; Lips, Paul; Luben, Robert; Metspalu, Andres; Meurs, van Joyce B.; Minster, Ryan L.; Orwoll, Erick; Oei, Edwin; Psaty, Bruce M.; Raitakari, Olli T.; Ralston, Stuart W.; Ridker, Paul M.; Robbins, John A.; Smith, Albert V.; Styrkarsdottir, Unnur; Tranah, Gregory J.; Thorstensdottir, Unnur; Uitterlinden, Andre G.; Zmuda, Joseph; Zillikens, M.C.; Ntzani, Evangelia E.; Evangelou, Evangelos; Ioannidis, John P.A.; Evans, David M.; Ohlsson, Claes

    2017-01-01

    Hand grip strength is a widely used proxy of muscular fitness, a marker of frailty, and predictor of a range of morbidities and all-cause mortality. To investigate the genetic determinants of variation in grip strength, we perform a large-scale genetic discovery analysis in a combined sample of

  16. Bolted Ribs Analysis for the ITER Vacuum Vessel using Finite Element Submodelling Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Zarzalejos, José María, E-mail: jose.zarzalejos@ext.f4e.europa.eu [External at F4E, c/Josep Pla, n.2, Torres Diagonal Litoral, Edificio B3, E-08019, Barcelona (Spain); Fernández, Elena; Caixas, Joan; Bayón, Angel [F4E, c/Josep Pla, n.2, Torres Diagonal Litoral, Edificio B3, E-08019, Barcelona (Spain); Polo, Joaquín [Iberdrola Ingeniería y Construcción, Avenida de Manoteras 20, 28050 Madrid (Spain); Guirao, Julio [Numerical Analysis Technologies, S L., Marqués de San Esteban 52, Entlo, 33209 Gijon (Spain); García Cid, Javier [Iberdrola Ingeniería y Construcción, Avenida de Manoteras 20, 28050 Madrid (Spain); Rodríguez, Eduardo [Mechanical Engineering Department EPSIG, University of Oviedo, Gijon (Spain)

    2014-10-15

    Highlights: • The ITER Vacuum Vessel Bolted Ribs assemblies are modelled using Finite Elements. • Finite Element submodelling techniques are used. • Stress results are obtained for all the assemblies and a post-processing is performed. • All the elements of the assemblies are compliant with the regulatory provisions. • Submodelling is a time-efficient solution to verify the structural integrity of this type of structures. - Abstract: The ITER Vacuum Vessel (VV) primary function is to enclose the plasmas produced by the ITER Tokamak. Since it acts as the first radiological barrier of the plasma, it is classified as a class 2 welded box structure, according to RCC-MR 2007. The VV is made of an inner and an outer D-shape, 60 mm-thick double shell connected through thick massive bars (housings) and toroidal and poloidal structural stiffening ribs. In order to provide neutronic shielding to the ex-vessel components, the space between shells is filled with borated steel plates, called In-Wall Shielding (IWS) blocks, and water. In general, these blocks are connected to the IWS ribs which are connected to adjacent housings. The development of a Finite Element model of the ITER VV including all its components in detail is unaffordable from the computational point of view due to the large number of degrees of freedom it would require. This limitation can be overcome by using submodelling techniques to simulate the behaviour of the bolted ribs assemblies. Submodelling is a Finite Element technique which allows getting more accurate results in a given region of a coarse model by generating an independent, finer model of the region under study. In this paper, the methodology and several simulations of the VV bolted ribs assemblies using submodelling techniques are presented. A stress assessment has been performed for the elements involved in the assembly considering possible types of failure and including stress classification and categorization techniques to analyse

  17. On the plastic behaviour of multi directional epoxy-bolted CFRP laminates

    DEFF Research Database (Denmark)

    Jensen, Aage; Poulsen, Ervin

    2004-01-01

    The second generation of CFRP laminate has recently been developed. It is a multi directional CFRP laminate, i.e. a laminate with carbon fibres having several directions other than the first generation. The paper describes the laboratory tests carried out in order to develop anchorage devices...... for such multi directional CFRP laminates which are epoxy-bonded and bolted or nailed to the concrete substrate for the purpose of strengthening against failure caused by bending. The tests were carried out at the Technical University of Denmark, IABM and Byg-DTU...

  18. The nuts and bolts of proofs an introduction to mathematical proofs

    CERN Document Server

    Cupillari, Antonella

    2005-01-01

    The Nuts and Bolts of Proof instructs students on the basic logic of mathematical proofs, showing how and why proofs of mathematical statements work. It provides them with techniques they can use to gain an inside view of the subject, reach other results, remember results more easily, or rederive them if the results are forgotten.A flow chart graphically demonstrates the basic steps in the construction of any proof and numerous examples illustrate the method and detail necessary to prove various kinds of theorems.* The "List of Symbols" has been extended.* Set Theory section has been strengthened with more examples and exercises.* Addition of "A Collection of Proofs"

  19. Bolted Joints in Composite Structures: Design, Analysis and Verification. Task II. Test Results--Multifastener Joints

    Science.gov (United States)

    1985-08-01

    THE AXIAL LOADS DIFFERENCE PER IOLT 3»e#.« POUNDS POUNDS CEOM 1 3828.8 A B 171.2 POUNDS 8S.6 POUNDS HOLE IOLT ID 23* DEC. 28* DEC...ee.e POUNDS POUNDS CEOM 1 61.1 A B 38.9 POUNDS 19.5 POUNDS HOLE BOLT ID 236 DEC. 281 DEC. (VOLTS) 31 33 -3.89 -2.41 t.72 1.11...ALL IOLTS THE DIFFERENCE IETUEEN THE IOLT SURVEY LOAD AND THE SUN OF THE AXIAL LOADS DIFFERENCE PER IOLT saee. e POUNDS POUNDS CEOM 1 p

  20. Numerical analysis of bolted connections in cold-formed steel members

    Directory of Open Access Journals (Sweden)

    Jorge Munaiar Neto

    2006-02-01

    Full Text Available This paper presents three-dimensional numerical models of bolted connections of cold-formed steel members. The purpose of three-dimensional numerical models is to evaluate the strength and the behavior of these connections. The computer code ANSYS v. 6.0, based on Finite Element Method, was used to analyze the numerical models response. In order to evaluate the efficiency and reliability of the constructed models, the numerical results were compared with experimental results obtained from experimental assays carried out in Structures Laboratory of EESC/USP. In this sense, the numerical results presented satisfactory agreement when compared with experimental results.

  1. Analytical and numerical investigation of bolted steel ring flange connection for offshore wind monopile foundations

    DEFF Research Database (Denmark)

    Madsen, C.A.; Kragh-Poulsen, Jens-Christian; Tage, K.J.

    The monopile foundation is the dominant solution for support of wind turbines in offshore wind farms. It is normally grouted to the transition piece which connects the foundation to the turbine. Currently, the bolted steel ring flange connection is investigated as an alternative. The monopile......--transition piece connection has specific problems, such as out-of-verticality and installation damage from driving the MP into the seabed and it is not fully known how to design for these. This paper presents the status of the ongoing development work and an estimate of what still needs to be covered in order...

  2. Traducción de elementos culturales en A man for all seasons, de Robert Bolt

    OpenAIRE

    Currás Móstoles, María Rosa

    2010-01-01

    Esta tesis doctoral se centra en el estudio del tratamiento de los referentes culturales en A Man for All Seasons, de Robert Bolt. Partiendo del hecho de que los textos literarios son productos de la cultura que los alojan, una obra literaria manifiesta su adscripción a dicha cultura por medio de ciertos elementos conocidos como referentes culturales. La importancia de los elementos culturales en traducción viene reforzada por la consideración de que los estudios de traducción actualmen...

  3. Friction coefficient dependence on electrostatic tribocharging.

    Science.gov (United States)

    Burgo, Thiago A L; Silva, Cristiane A; Balestrin, Lia B S; Galembeck, Fernando

    2013-01-01

    Friction between dielectric surfaces produces patterns of fixed, stable electric charges that in turn contribute electrostatic components to surface interactions between the contacting solids. The literature presents a wealth of information on the electronic contributions to friction in metals and semiconductors but the effect of triboelectricity on friction coefficients of dielectrics is as yet poorly defined and understood. In this work, friction coefficients were measured on tribocharged polytetrafluoroethylene (PTFE), using three different techniques. As a result, friction coefficients at the macro- and nanoscales increase many-fold when PTFE surfaces are tribocharged, but this effect is eliminated by silanization of glass spheres rolling on PTFE. In conclusion, tribocharging may supersede all other contributions to macro- and nanoscale friction coefficients in PTFE and probably in other insulating polymers.

  4. Friction and Wear in Timing Belt Drives

    Directory of Open Access Journals (Sweden)

    B. Stojanovic

    2010-09-01

    Full Text Available Timing belt tooth goes into contact with a drive pulley, stretched to the maximum, because of the previous tension. When the contact begins the peak of the belt tooth makes the contact with the outer surface of the pulley teeth. The process of the teeth entering into the contact zone is accompanied with the relative sliding of their side surfaces and appropriate friction force. The normal force value is changing with the parabolic function, which also leads to the changes of the friction force. The biggest value of the normal force and of the friction force is at the tooth root. Hollow between teeth and the tip of the pulley teeth are also in contact. Occasionally, the face surface of the belt and the flange are also in contact. The friction occurs in those tribomechanical systems, also. Values of these friction forces are lower compared with the friction force, which occurs at the teeth root.

  5. Static friction between rigid fractal surfaces.

    Science.gov (United States)

    Alonso-Marroquin, Fernando; Huang, Pengyu; Hanaor, Dorian A H; Flores-Johnson, E A; Proust, Gwénaëlle; Gan, Yixiang; Shen, Luming

    2015-09-01

    Using spheropolygon-based simulations and contact slope analysis, we investigate the effects of surface topography and atomic scale friction on the macroscopically observed friction between rigid blocks with fractal surface structures. From our mathematical derivation, the angle of macroscopic friction is the result of the sum of the angle of atomic friction and the slope angle between the contact surfaces. The latter is obtained from the determination of all possible contact slopes between the two surface profiles through an alternative signature function. Our theory is validated through numerical simulations of spheropolygons with fractal Koch surfaces and is applied to the description of frictional properties of Weierstrass-Mandelbrot surfaces. The agreement between simulations and theory suggests that for interpreting macroscopic frictional behavior, the descriptors of surface morphology should be defined from the signature function rather than from the slopes of the contacting surfaces.

  6. Relations between the inflection point on the force-time curve and force-time parameters during static explosive grip.

    Science.gov (United States)

    Ikemoto, Yukio; Demura, Shinichi; Yamaji, Shunsuke

    2004-04-01

    Individual differences in muscle contractile speed during static explosive muscle contraction are reflected in the developmental phase of the force-time curve. The purposes of this study were to clarify the properties and reliability of the inflection point of force-time, statistically dividing speed during static explosive grip into two phases and to assess the relations between that inflection point and others. Static explosive grip data were measured two times with a 5-min. rest (sampling frequency; 100 Hz). 32 healthy, young men (age: 15.5 +/- 0.8 yr., height: 173.9 +/- 7.3 cm, body mass: 71.5 +/- 11.2 kg) participated. 8 static explosive grip parameters were selected: time of reaching, integrated area, and quotient values of the integrated areas up to 0.25, 0.5, and 1.0 sec. divided by maximal grip force. The inflection point was calculated statistically from two regression lines fitted to a developmental phase and the almost steady-state phase of reaching maximal grip force by applying a two-phase regression model. The reliabilities of maximal grip force, time of reaching 90% of maximal grip force, and the integrated area until 0.5 sec. and 1.0 sec. after the onset of grip were good (ICC=.77 to .93). The time of reaching an inflection force value appeared at 0.3 sec. after the onset of grip, corresponding to 80% of maximal grip force, and the reliabilities of the parameters regarding inflection point were good (ICC=.77 to .95). The time determined by boundary data between the former and the latter regression data set and the regression coefficient during the developmental phase correlated significantly with the time of reaching 90% of maximal grip force, the integrated area, and the quotient values of the integrated areas up to 0.25, 0.5, and 1.0 sec. divided by maximal grip force (rs=-.78 to -.96 and -.75 to 0.88, respectively, pforce. A force during the developmental phase and maximal grip force can depend on different physiological factors. The time

  7. A piezoelectric active sensing method for quantitative monitoring of bolt loosening using energy dissipation caused by tangential damping based on the fractal contact theory

    Science.gov (United States)

    Wang, Furui; Huo, Linsheng; Song, Gangbing

    2018-01-01

    Monitoring of bolt looseness is essential for ensuring the safety and reliability of equipment and structures with bolted connections. It is well known that tangential damping has an important influence on energy dissipation during wave propagation across the bolted joints, which require different levels of preload. In this paper, the energy dissipation generated by tangential damping of the bolted joints under different bolt preloads was modeled analytically based on fractal contact theory, which took the imperfect interface into account. A saturation value exists with the increase of the bolt preload, and the center frequency of emitted signal is demonstrated to affect the received energy significantly. Compared with previous similar studies based on experimental techniques and numerical method, the investigation presented in this paper explains the phenomenon from the inherent mechanism, and achieves the accurate quantitative monitoring of bolt looseness directly, rather than an indirect failure index. Finally, the validity of the proposed method in this paper was demonstrated with an experimental study of a bolted joint with different preload levels.

  8. Performance of Link-To-Stub Bolted Connection in Column-Tree Moment Resisting Frames under Fire Conditions

    Directory of Open Access Journals (Sweden)

    Mahmood Yahyai

    2015-12-01

    Full Text Available Column-tree moment resisting frames, as the efficient shop-welded and field-bolted structural systems, are used in many countries. Very limited research has been carried out on such systems under fire conditions. This paper presents experimental investigations of the behavior of beam and bolted splice connections in steel column-tree moment resisting frames exposed to fire. Two full-scale steel sub-frames with different splice connections were tested under ISO 834 standard fire. The flange splice plates were configured as a single plate with single shear bolts in first specimen, and as double plates with double shear bolts in second specimen. The observation of thermal and structural fire behaviors including temperature histories, temperature-deflection of the beam, temperature-rotation of splice connections and failure modes were investigated. The temperature-deflection and temperature-rotation curves remained in the elastic range until about 600°C. Beyond 600°C, the behavior would be highly nonlinear plastic. The beam splice connection failed due to shear fracture of top bolts at temperatures beyond 750°C. Consequently, stub beam web failed at those temperatures because of block-shear. Using double plates with double shear bolts for flange splices would enhance the temperature resistance and rotational capacity of the beam splice connections. Both tests results confirmed that specimens retain the capacity to support the design load when the average beam temperature does not exceed 600°C. This temperature limit confirms the temperature criteria provided by ASTM E119 and ANSI/UL 263 for a restrained beam, and can be used to specify the minimum fire resistance criteria for beams in column-tree MRFs. The measured time-deflection curves showed that the restrained fire resistance rating for both unprotected specimens obtained about 15 minutes in both tests.

  9. Result from systematic compilation of barrel bolt findings in S/KWU type PWRs in the context of computational analysis

    International Nuclear Information System (INIS)

    Kilian, R.; Devrient, B.; Koenig, G.; Stanislowski, M.; Widera, M.; Beusekom, R. van; Wermelinger, T.

    2015-01-01

    In 2005 intergranular stress corrosion cracking (IGSCC) of barrel bolts was observed in several S/KWU type PWRs. The bolts, known as star bolts, are made of SS type 316 Ti (German Material No. 1.4571 K) bars which are cold worked to adjust the required mechanical properties. This damage mechanism was so far less understood for PWR primary conditions. Therefore an extended joint research program was launched by AREVA GmbH and VGB e.V. to clarify the specific conditions which contributed to the observed findings on barrel bolts. A systematic analysis of the IGSCC affecting parameters as material, heats, environment and mechanical load was performed based on a plant data compilation from all six S/KWU PWRs with comparable core barrel design using barrel and baffle bolts made from type 316Ti. Using the outcome of this systematic data compilation additional computational fluid dynamics calculations in combination with radiolysis calculations were performed. The results showed that by a combination of reduced volume exchange by local flow conditions and radiolysis reactions forming oxidizing species as dissolved oxygen and/or hydrogen peroxide may locally affect the corrosion behavior of cold worked austenitic stainless steels. Therefore, small local volumes with oxidizing water chemistry conditions are assumed to lead to the IGSCC of cold worked type 316Ti. The comparison of the initial cold worked microstructure by TEM with the cold worked and in service irradiated microstructure (void formation, dislocation loop density, etc.) clearly reveals that neutron irradiation hardening in terms of IASCC (Irradiation-Assisted Stress Corrosion Cracking) is not the leading mechanism for these cases of barrel bolt cracking in the analyzed PWRs. (authors)

  10. Noise and vibration in friction systems

    CERN Document Server

    Sergienko, Vladimir P

    2015-01-01

    The book analyzes the basic problems of oscillation processes and theoretical aspects of noise and vibration in friction systems. It presents generalized information available in literature data and results of the authors in vibroacoustics of friction joints, including car brakes and transmissions. The authors consider the main approaches to abatement of noise and vibration in non-stationary friction processes. Special attention is paid to materials science aspects, in particular to advanced composite materials used to improve the vibroacoustic characteristics of tribopairs The book is intended for researchers and technicians, students and post-graduates specializing in mechanical engineering, maintenance of machines and transport means, production certification, problems of friction and vibroacoustics.

  11. Effect of grafted oligopeptides on friction.

    Science.gov (United States)

    Iarikov, Dmitri D; Ducker, William A

    2013-05-14

    Frictional and normal forces in aqueous solution at 25 °C were measured between a glass particle and oligopeptide films grafted from a glass plate. Homopeptide molecules consisting of 11 monomers of either glutamine, leucine, glutamic acid, lysine, or phenylalanine and one heteropolymer were each "grafted from" an oxidized silicon wafer using microwave-assisted solid-phase peptide synthesis. The peptide films were characterized using X-ray photoelectron spectroscopy and secondary ion mass spectrometry. Frictional force measurements showed that the oligopeptides increased the magnitude of friction compared to that on a bare hydrophilic silicon wafer but that the friction was a strong function of the nature of the monomer unit. Overall we find that the friction is lower for more hydrophilic films. For example, the most hydrophobic monomer, leucine, exhibited the highest friction whereas the hydrophilic monomer, polyglutamic acid, exhibited the lowest friction at zero load. When the two surfaces had opposite charges, there was a strong attraction, adhesion, and high friction between the surfaces. Friction for all polymers was lower in phosphate-buffered saline than in pure water, which was attributed to lubrication via hydrated salt ions.

  12. Friction & Wear Under Very High Electromagnetic Stress

    National Research Council Canada - National Science Library

    Cowan, Richard S; Danyluk, Steven; Moon, Francis; Ford, J. C; Brenner, Donald W

    2004-01-01

    This document summarizes initial progress toward advancing the fundamental understanding of the friction, wear and mechanics of interfaces subjected to extreme electromagnetic stress, high relative...

  13. EFFECT OF ECCENTRIC EXERCISE PROGRAMME ON PAIN AND GRIP STRENGTH FOR SUBJECTS WITH MEDIAL EPICONDYLITIS

    Directory of Open Access Journals (Sweden)

    Mishra Prashant Akhilesh

    2014-04-01

    Full Text Available Background and Objective: Therapeutic eccentric exercise may provide both a structural and functional benefit during tendinopathy rehabilitation. The objective is to find the effect of eccentric exercises on improvement of pain and grip strength for subjects with Medial Epicondylitis. Method: Pre to post test experimental study design randomized thirty subjects with medial epicondylitis, 15 each into Group A and Group B. Group B subjects were treated with conventional therapy and Eccentric exercises. Group A subjects were treated with conventional therapy. Results: When means of post intervention were compared using Independent ‘t’ between groups there was no statistically significant difference in improvements obtained in VAS scores and grip strength. There was a statistically significant change in means of VAS score and Grip strength when means were analyzed by using Paired‘t’ test and Wilcoxon signed rank test within the groups with positive percentage of change. Conclusion: It is concluded that four weeks of Eccentric Exercise Programme combined with conventional therapy shown significant effect on improving pain and Grip strength, however the improvement obtained has no difference when compared with control conventional treatment for Subjects with Medial Epicondylitis.

  14. The Effects of Unit Exercises on the Hand Grip Strength of Arm Wrestlers

    Science.gov (United States)

    Yonca, Sezer S.; Engin, Çelikel B.; Serdar, Yücel A.; Mustafa, Karadag; Yüksel, Savucu

    2017-01-01

    The aim of this research is to evaluate the change in the hand grip strength of the male arm wrestlers before and after a unit of exercise. The participants of the research consist of sportsmen (n=16) of Firat University arm wrestling team in 18-25 age group. Within the scope of the research, all of the tests and measurements (age, length, body…

  15. On automatic determination of movement phases in manual transport during the precision grip.

    Science.gov (United States)

    Hosseini, N; Hejdukova, B; Ingvarsson, P E; Johnels, B; Olsson, T

    2000-01-01

    Integrated movement and force analysis of the precision grip-lift sequence (grasping an object between index finger and thumb) is a useful tool in studies on manipulative hand functions. The everyday Manual Transport tasks, moving objects from one place to another, exhibits powerful test possibilities because it includes the precision grip. In this study, as a step towards the exploitation of these possibilities, we created an algorithm that extracts sequence of phases in this task. The mathematical and dynamical properties of the movement and force signals were used to determine the start and the end of each phase. The grip-lift synergy was quantified by the correlation coefficient during each phase. Eight patients with Parkinson's Disease (PD) and 10 healthy persons were studied. The PD patients were tested both in the medicated (ON) and the unmedicated (OFF) state. The object was lifted with the index finger and the thumb, moved a short distance, and put down on a shelf. The preliminary results of these experiments displayed significantly higher coordination between the grip and load forces in the initial phases, before the lift was completely established, than during the transport phases. This was evident both in PD patients and healthy subjects. This method provides an automatic analysis of the motor performance during an arm-hand movement that is important in daily life to aid in clinical diagnosis.

  16. Precision grip in congenital and acquired hemiparesis: similarities in impairments and implications for neurorehabilitation - review

    Directory of Open Access Journals (Sweden)

    Yannick eBleyenheuft

    2014-06-01

    Full Text Available Background: Patients with congenital and acquired hemiparesis incur long-term functional deficits, among which the loss of prehension that may impact their functional independence. Identifying, understanding and comparing the underlying mechanisms of prehension impairments represent an opportunity to better adapt neurorehabilitationObjective: The present review aims to provide a better understanding of precision grip deficits in congenital and acquired hemiparesis and to determine whether the severity and type of fine motor control impairments depend on whether or not the lesions are congenital or acquired in adulthood. Methods: Using combinations of the following key words: fingertip force, grip force, precision grip, cerebral palsy, stroke, pubmed and Scopus databases were used to search studies from 1984 to 2013. Results: Individuals with both congenital and acquired hemiparesis were able to some extent to use anticipatory motor control in precision grip tasks, even if this control was impaired in the paretic hand. In both congenital or acquired hemiparesis, the ability to plan efficient anticipatory motor control when the less-affected hand is used provides a possibility to remediate impairments in anticipatory motor control of the paretic hand. Conclusion: Surprisingly we observed very few differences between the results of studies in children with congenital hemiplegia and stroke patients. We suggest that the underlying specific strategies of neurorehabilitation developed for each one could benefit the other.

  17. Why Carcinus maenas cannot get a grip on South Africa's wave ...

    African Journals Online (AJOL)

    Why Carcinus maenas cannot get a grip on South Africa's wave-exposed coastline. SL Hampton, CL Griffiths. Abstract. The European green crab Carcinus maenas has established considerable breeding populations in harbours and sheltered bays in the South-Western Cape, South Africa, but appears unable to flourish on ...

  18. Effect of cervical spine manipulative therapy on judo athletes' grip strength.

    Science.gov (United States)

    Botelho, Marcelo B; Andrade, Bruno B

    2012-01-01

    The objective of this study was to perform an investigation evaluating if cervical spinal manipulative therapy (SMT) can increase grip strength on judo athletes in a top 10 national-ranked team. A single-blinded, prospective, comparative, pilot, randomized, clinical trial was performed with 18 athletes of both sexes from a judo team currently competing on a national level. The athletes were randomly assigned to 2 groups: chiropractic SMT and sham. Three interventions were performed on each of the athletes at different time points. Force measurements were obtained by a hydraulic dynamometer immediately before and after each intervention at the same period before training up to 3 weeks with at least 36 hours between interventions. Analysis of grip strength data revealed a statistically significant increase in strength within the treatment group after the first intervention (6.95% right, 12.61% left) as compared with the second (11.53% right, 17.02% left) and the third interventions (10.53% right, 16.81% left). No statistically significant differences were found in grip strength comparison within the sham group. Overall differences in strength were consistently significant between the study groups (P = .0025). The present study suggests that the grip strength of national level judo athletes receiving chiropractic SMT improved compared to those receiving sham. Copyright © 2012 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

  19. Applying support vector regression analysis on grip force level-related corticomuscular coherence

    DEFF Research Database (Denmark)

    Rong, Yao; Han, Xixuan; Hao, Dongmei

    2014-01-01

    to compare the corticomuscular coherence in the alpha (7–15Hz), beta (15–30Hz) and gamma (30–45Hz) band at 25 % maximum grip force (MGF) and 75 % MGF. Results show that ESVR could reduce the influence of deflected signals and summarize the overall behavior of multiple coherence curves. Coherence proportion...

  20. Evaporation over a heterogeneous land surface - The EVA-GRIPS project

    NARCIS (Netherlands)

    Mengelkamp, H.T.; Beyrich, F.; Heinemann, G.; Ament, F.; Bange, J.; Berger, F.; Bosenberg, J.; Foken, T.; Hennemuth, B.; Heret, C.; Huneke, S.; Johnsen, K.P.; Kerschgens, M.; Kohsiek, W.; Leps, J.P.; Liebethal, C.; Lohse, H.; Mauder, M.; Meijninger, W.M.L.; Raasch, S.; Simmer, C.

    2006-01-01

    The representation of subgrid-scale surface heterogeneities in numerical weather and climate models has been a challenging problem for more than a decade. The Evaporation at Grid and Pixel Scale (EVA-GRIPS) project adds to the numerous studies on vegetation-atmosphere interaction processes through a

  1. Grip strength and quality of life in the second half of life: hope as a moderator.

    Science.gov (United States)

    Gum, Amber M; Segal-Karpas, Dikla; Avidor, Sharon; Ayalon, Liat; Bodner, Ehud; Palgi, Yuval

    2017-09-28

    The purpose of the current study was to investigate grip strength, hope, and their interaction as predictors of quality of life four years later in a nationally representative sample of older adults. Data were derived from the first (2005-2006) and second wave (2009) of the Israeli component of the Survey of Health Ageing and Retirement in Europe (SHARE; N = 344). Hope was measured by three items from the Hope   Scale, and quality of life was measured by the CASP-12 (Control, Autonomy, Self-Realization, and Pleasure). Multiple regression analyses were conducted. Grip strength at T1 predicted QoL in T2, but hope was not a significant predictor. Furthermore, hope moderated the effect of handgrip on QoL, such that the effect was weaker for higher levels of hope. As hypothesized, hope acted as a moderator, such that poor grip strength was associated with worse QoL for less hopeful older adults, but grip strength was not associated with QoL for more hopeful older adults. Findings are consistent with a theoretical conceptualization of hope as a buffer between physical challenges and negative outcomes like QoL. Encouraging a hopeful perspective could enhance QoL for older adults with decreased muscle strength.

  2. High-strength bolt-forming of fine-grained aluminum alloy 6061 with a continuous hybrid process

    International Nuclear Information System (INIS)

    Kim, Ji Hun; Hwang, Sun Kwang; Im, Yong-Taek; Son, Il-Heon; Bae, Chul Min

    2012-01-01

    Highlights: ► Fine-grained AA6061-O was produced by a continuous hybrid process. ► It consists of rolling, ECAP, and drawing. ► High-strength bolt was manufactured with the fine-grained AA6061-O. ► The UTS and micro-hardness of the bolt was increased by 50%. ► The route C was better in making a uniform micro-hardness distribution in the bolt. - Abstract: It is well known that the development of a continuous manufacturing process to apply severe plastic deformation (SPD) is a major challenge for industrial usages to improve the mechanical properties of the material through grain refinement. In this study, fine-grained AA6061-O wire was manufactured by a two-pass hybrid process consisting of drawing, equal channel angular pressing and rolling in a continuous manner to investigate the effects of processing routes for two different routes, A and C, on the variation of ultimate tensile strength (UTS) and micro-hardness distribution. The UTS value (185 MPa) of the specimen processed by the two-pass hybrid process with route A was higher than that of 171 MPa obtained from the two-pass wire-drawing process and was equivalent to the level of 184 MPa processed by the three-pass wire-drawing process. The average micro-hardness value (Hv 58.0) obtained from the two-pass hybrid process through route C was the highest among all the cases. According to transmission electron microscopy, the original grain was subdivided and elongated owing to deformation during the processes. The specimen processed by the two-pass hybrid process through route C showed smaller deformation bands and had potentially higher angle grain boundaries compared to the specimen processed by the two-pass wire-drawing process. Finally, the high-strength bolt was manufactured using the fine-grained AA6061-O wire prepared by the continuous hybrid process to check its formability. A ductile fracture at the first thread right above the jaw was observed in the bolt tension test of the manufactured bolt

  3. Operational experience with ultrasonic bolt seals for safeguards containment of multielement bottles in THORP spent-fuel storage ponds

    International Nuclear Information System (INIS)

    Hatt, C.D.; Reynolds, A.F.; Jeffrey, A.

    1995-01-01

    This paper describes the operational experience gained by British Nuclear Fuels Limited (BNFL) at the THORP spent-fuel storage facility in the application and verification of ultra-sonic bolt seals to light water reactor fuel containers and multielement bottles while in the storage ponds. Additionally, it discusses BNFL's cooperation with the International Atomic Energy Agency, Euratom, and Joint Research Council-Ispra to facilitate the development and design modifications of the remote-handling tools used. Finally, it summarizes the benefits, from an operator's point of view, of using the bolt seals as a safeguards/containment device

  4. Characterization of friction and wear behavior of friction modifiers used in wheel-rail contacts

    NARCIS (Netherlands)

    Oomen, M. A.; Bosman, R.; Lugt, P. M.

    2017-01-01

    Reliable traction between wheel and rail is an important issue in the railway industry. To reduce variations in the coefficient of friction, so-called “friction modifiers” (carrier with particles) are used. Twin-disk tests were done with three commercial friction modifiers, based on different

  5. A Physics-Based Rock Friction Constitutive Law: Steady State Friction

    Science.gov (United States)

    Aharonov, Einat; Scholz, Christopher H.

    2018-02-01

    Experiments measuring friction over a wide range of sliding velocities find that the value of the friction coefficient varies widely: friction is high and behaves according to the rate and state constitutive law during slow sliding, yet markedly weakens as the sliding velocity approaches seismic slip speeds. We introduce a physics-based theory to explain this behavior. Using conventional microphysics of creep, we calculate the velocity and temperature dependence of contact stresses during sliding, including the thermal effects of shear heating. Contacts are assumed to reach a coupled thermal and mechanical steady state, and friction is calculated for steady sliding. Results from theory provide good quantitative agreement with reported experimental results for quartz and granite friction over 11 orders of magnitude in velocity. The new model elucidates the physics of friction and predicts the connection between friction laws to independently determined material parameters. It predicts four frictional regimes as function of slip rate: at slow velocity friction is either velocity strengthening or weakening, depending on material parameters, and follows the rate and state friction law. Differences between surface and volume activation energies are the main control on velocity dependence. At intermediate velocity, for some material parameters, a distinct velocity strengthening regime emerges. At fast sliding, shear heating produces thermal softening of friction. At the fastest sliding, melting causes further weakening. This theory, with its four frictional regimes, fits well previously published experimental results under low temperature and normal stress.

  6. Calpain-GRIP Signaling in Nucleus Accumbens Core Mediates the Reconsolidation of Drug Reward Memory.

    Science.gov (United States)

    Liang, Jie; Li, Jia-Li; Han, Ying; Luo, Yi-Xiao; Xue, Yan-Xue; Zhang, Yàn; Zhang, Yán; Zhang, Li-Bo; Chen, Man-Li; Lu, Lin; Shi, Jie

    2017-09-13

    Exposure to drug-paired cues causes drug memories to be in a destabilized state and interfering with memory reconsolidation can inhibit relapse. Calpain, a calcium-dependent neutral cysteine protease, is involved in synaptic plasticity and the formation of long-term fear memory. However, the role of calpain in the reconsolidation of drug reward memory is still unknown. In the present study, using a conditioned place preference (CPP) model, we found that exposure to drug-paired contextual stimuli induced the activation of calpain and decreased the expression of glutamate receptor interacting protein 1 (GRIP1) in the nucleus accumbens (NAc) core, but not shell, of male rats. Infusions of calpain inhibitors in the NAc core immediately after retrieval disrupted the reconsolidation of cocaine/morphine cue memory and blocked retrieval-induced calpain activation and GRIP1 degradation. The suppressive effect of calpain inhibitors on the expression of drug-induced CPP lasted for at least 14 d. The inhibition of calpain without retrieval 6 h after retrieval or after exposure to an unpaired context had no effects on the expression of reward memory. Calpain inhibition after retrieval also decreased cocaine seeking in a self-administration model and this effect did not recover spontaneously after 28 d. Moreover, the knock-down of GRIP1 expression in the NAc core by lentivirus-mediated short-hairpin RNA blocked disruption of the reconsolidation of drug cue memories that was induced by calpain inhibitor treatment. These results suggest that calpain activity in the NAc core is crucial for the reconsolidation of drug reward memory via the regulation of GRIP1 expression. SIGNIFICANCE STATEMENT Calpain plays an important role in synaptic plasticity and long-term memory consolidation, however, its role in the reconsolidation of drug cue memory remains unknown. Using conditioned place preference and self-administration procedures, we found that exposure to drug-paired cues induced the

  7. A real-time visual inspection method of fastening bolts in freight car operation

    Science.gov (United States)

    Nan, Guo; Yao, JunEn

    2015-10-01

    A real-time inspection of the key components is necessary for ensuring safe operation of freight car. While traditional inspection depends on the trained human inspectors, which is time-consuming and lower efficient. With the development of machine vision, vision-based inspection methods get more railway on-spot applications. The cross rod end fastening bolts are important components on both sides of the train body that fixing locking plates together with the freight car main structure. In our experiment, we get the images containing fastening bolt components, and accurately locate the locking plate position using a linear Support Vector Machine (SVM) locating model trained with Histograms of Oriented Gradients (HOG) features. Then we extract the straight line segment using the Line Segment Detector (LSD) and encoding them in a range, which constitute a straight line segment dataset. Lastly we determine the locking plate's working state by the linear pattern. The experiment result shows that the localization accurate rate is over 99%, the fault detection rate is over 95%, and the module implementation time is 2f/s. The overall performance can completely meet the practical railway safety assurance application.

  8. Difference of proteomics vernalization-induced in bolting and flowering transitions of Beta vulgaris.

    Science.gov (United States)

    Liang, Naiguo; Cheng, Dayou; Liu, Qiaohong; Cui, Jie; Luo, Chengfei

    2018-02-01

    Sugar beet (Beta vulgaris) is a biennial crop that accounts for 30% sugar production of the world. Vernalization is an essential factor for sugar beet reproductative growth under long days. Although genes association with bolting and flowering were well explored, the difference of proteomics in the two growth stages were still poorly understood. To address the molecular mechanism at the level of proteins, an isobaric tags for relative and absolute quantification (iTRAQ)-based quantitative proteomics approach was employed to the three different growth stages (germination, bolting, flowering) of vernalized samples and the corresponding stage germination (17W weeks), 19W and 20W of nonvernalized samples. A total of 1110 peptides, 842 unique peptides and 570 proteins were identified. Most of them were assigned to phenylpropanoid biosynthesis, hormone metabolism and protein processing pathway. IAA and Gibberellins (GA3) promoted growth and development in a threshold manner at growth stage germination after vernalization. A novel discovery was that IAA biosynthetic pathway of sugar beet was the Trp-dependent. In addition, two predominant pathways of protein processing association with vernalization were also identified in sugar beet at growth stage flowering. This study provided an in-depth understanding of the molecular mechanism of vernalization at the level of proteomics. Copyright © 2017 The Authors. Published by Elsevier Masson SAS.. All rights reserved.

  9. Experimental study of bolted connections using light gauge channel sections and packing plates at the joints

    Science.gov (United States)

    Kulkarni, Ravindra B.; Vaghe, Vishal M.

    2014-12-01

    Cold-formed structural members are being used more widely in routine structural design as the world steel industry moves from the production of hot-rolled section and plate to coil and strip, often with galvanized and/or painted coatings. Steel in this form is more easily delivered from the steel mill to the manufacturing plant where it is usually cold-rolled into open and closed section members. In the present experimental study, the use of packing plate at the joints in cold-formed channel sections may increase the load carrying capacity and also reduce the buckling of unconnected cold form channel steel plate at joints. The present study focuses on examining the experimental investigation to use mild steel as a packing plate with cold-formed channel sections by bolted connection at the joints and the connection subjected to axial tension. Series of tests are carried out with increase in the thickness of packing plate and results are observed and analyzed. Total Twelve experimental tests have been carried out on cold-formed channel tension members fastened with single as well as three numbers of bolts at the connection and from the observations the strength of the joint is increased by increasing the various thicknesses of packing plates and also the buckling of unconnected leg of channel specimen is reduced. It is analyzed by plotting the entire load versus elongation path, so that the behavior of the connection is examined.

  10. Acoustics and its relation to language: The influence of Dick Bolt

    Science.gov (United States)

    Stevens, Kenneth N.

    2003-04-01

    Under the mentoring of Dick Bolt, and the stimulation he provided in the Acoustics Laboratory at MIT, many students were exposed to a range of topics in acoustics, including mechanisms of sound generation, radiation, and propagation, noise control, acoustics of resonators and rooms, human responses to sound, and speech perception under various adverse conditions. As someone who became interested in speech communication, I have recognized that this kind of quantitative background in acoustics is an important requirement for developing models of how humans produce speech, how they perceive and understand speech, and how children acquire these skills. Speech production involves sound sources produced by a nonlinear mechanical system and by noise arising from turbulent airflow. Sound is propagated in a vocal tract with yielding walls, and acoustic coupling is introduced by lossy resonators attached to the vocal tract, including the trachea and the nasal cavity. These acoustic principles of sound generation create an inventory of sound types that give rise to distinctive responses in the ears and brains of listeners. The solid grounding in acoustics provided by Dick Bolt and his leadership have helped in the formation of this linkage between acoustics, speech physiology, linguistics, and human perception.

  11. Visual feedback system to reduce errors while operating roof bolting machines.

    Science.gov (United States)

    Steiner, Lisa J; Burgess-Limerick, Robin; Eiter, Brianna; Porter, William; Matty, Tim

    2013-02-01

    Operators of roof bolting machines in underground coal mines do so in confined spaces and in very close proximity to the moving equipment. Errors in the operation of these machines can have serious consequences, and the design of the equipment interface has a critical role in reducing the probability of such errors. An experiment was conducted to explore coding and directional compatibility on actual roof bolting equipment and to determine the feasibility of a visual feedback system to alert operators of critical movements and to also alert other workers in close proximity to the equipment to the pending movement of the machine. The quantitative results of the study confirmed the potential for both selection errors and direction errors to be made, particularly during training. Subjective data confirmed a potential benefit of providing visual feedback of the intended operations and movements of the equipment. This research may influence the design of these and other similar control systems to provide evidence for the use of warning systems to improve operator situational awareness. Published by Elsevier Ltd.

  12. Directional control-response compatibility relationships assessed by physical simulation of an underground bolting machine.

    Science.gov (United States)

    Steiner, Lisa; Burgess-Limerick, Robin; Porter, William

    2014-03-01

    The authors examine the pattern of direction errors made during the manipulation of a physical simulation of an underground coal mine bolting machine to assess the directional control-response compatibility relationships associated with the device and to compare these results to data obtained from a virtual simulation of a generic device. Directional errors during the manual control of underground coal roof bolting equipment are associated with serious injuries. Directional control-response relationships have previously been examined using a virtual simulation of a generic device; however, the applicability of these results to a specific physical device may be questioned. Forty-eight participants randomly assigned to different directional control-response relationships manipulated horizontal or vertical control levers to move a simulated bolter arm in three directions (elevation, slew, and sump) as well as to cause a light to become illuminated and raise or lower a stabilizing jack. Directional errors were recorded during the completion of 240 trials by each participant Directional error rates are increased when the control and response are in opposite directions or if the direction of the control and response are perpendicular.The pattern of direction error rates was consistent with experiments obtained from a generic device in a virtual environment. Error rates are increased by incompatible directional control-response relationships. Ensuring that the design of equipment controls maintains compatible directional control-response relationships has potential to reduce the errors made in high-risk situations, such as underground coal mining.

  13. Development of elastomeric isolators to reduce roof bolting machine drilling noise.

    Science.gov (United States)

    Michael, Robert; Yantek, David; Johnson, David; Ferro, Ernie; Swope, Chad

    2011-11-01

    Among underground coal miners, hearing loss remains one of the most common occupational illnesses. In response to this problem, the National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) conducts research to reduce the noise emission of underground coal-mining equipment, an example of which is a roof bolting machine. Field studies show that, on average, drilling noise is the most significant contributor to a roof bolting machine operator's noise exposure. NIOSH OMSHR has determined that the drill steel and chuck are the dominant sources of drilling noise. NIOSH OMSHR, Corry Rubber Corporation, and Kennametal, Inc. have developed a bit isolator that breaks the steel-to-steel link between the drill bit and drill steel and a chuck isolator that breaks the mechanical connection between the drill steel and the chuck, thus reducing the noise radiated by the drill steel and chuck, and the noise exposure of the roof bolter operator. This paper documents the evolution of the bit isolator and chuck isolator including various alternative designs which may enhance performance. Laboratory testing confirms that production bit and chuck isolators reduce the A-weighted sound level generated during drilling by 3.7 to 6.6 dB. Finally, this paper summarizes results of a finite element analysis used to explore the key parameters of the drill bit isolator and chuck isolator to understand the impact these parameters have on noise.

  14. A Noble Approach of Process Automation in Galvanized Nut, Bolt Manufacturing Industry

    Directory of Open Access Journals (Sweden)

    Akash Samanta

    2012-05-01

    Full Text Available Corrosion costs money”, The Columbus battle institute estimates that corrosion costs Americans more than $ 220 billion annually, about 4.3% of the gross natural product [1].Now a days due to increase of pollution, the rate of corrosion is also increasing day-by-day mainly in India, so, to save the steel structures, galvanizing is the best and the simplest solution. Due to this reason galvanizing industries are increasing day-by-day since mid of 1700s.Galvanizing is a controlled metallurgical combination of zinc and steel that can provide a corrosion resistance in a wide variety of environment. In fact, the galvanized metal corrosion resistance factor can be some 70 to 80 times greater that the base metal material. Keeping in mind the importance of this industry, a noble approach of process automation in galvanized nut-bolt  manufacturing plant is presented here as nuts and bolts are the prime ingredient of any structure. In this paper the main objectives of any industry like survival, profit maximization, profit satisfying and sales growth are fulfilled. Furthermore the environmental aspects i.e. pollution control and energy saving are also considered in this paper. The whole automation process is done using programmable logic controller (PLC which has number of unique advantages like being faster, reliable, requires less maintenance and reprogrammable. The whole system has been designed and tested using GE, FANUC PLC.

  15. A Detailed Analysis of theBR1Locus Suggests a New Mechanism for Bolting after Winter in Sugar Beet (Beta vulgarisL.).

    Science.gov (United States)

    Tränkner, Conny; Lemnian, Ioana M; Emrani, Nazgol; Pfeiffer, Nina; Tiwari, Surya P; Kopisch-Obuch, Friedrich J; Vogt, Sebastian H; Müller, Andreas E; Schilhabel, Markus; Jung, Christian; Grosse, Ivo

    2016-01-01

    Sugar beet ( Beta vulgaris ssp. vulgaris) is a biennial, sucrose-storing plant, which is mainly cultivated as a spring crop and harvested in the vegetative stage before winter. For increasing beet yield, over-winter cultivation would be advantageous. However, bolting is induced after winter and drastically reduces yield. Thus, post-winter bolting control is essential for winter beet cultivation. To identify genetic factors controlling bolting after winter, a F 2 population was previously developed by crossing the sugar beet accessions BETA 1773 with reduced bolting tendency and 93161P with complete bolting after winter. For a mapping-by-sequencing analysis, pools of 26 bolting-resistant and 297 bolting F 2 plants were used. Thereby, a single continuous homozygous region of 103 kb was co-localized to the previously published BR 1 QTL for post-winter bolting resistance (Pfeiffer et al., 2014). The BR 1 locus was narrowed down to 11 candidate genes from which a homolog of the Arabidopsis CLEAVAGE AND POLYADENYLATION SPECIFICITY FACTOR 73-I ( CPSF73-I ) was identified as the most promising candidate. A 2 bp deletion within the BETA 1773 allele of BvCPSF73-Ia results in a truncated protein. However, the null allele of BvCPSF73-Ia might partially be compensated by a second BvCPSF73-Ib gene. This gene is located 954 bp upstream of BvCPSF73-Ia and could be responsible for the incomplete penetrance of the post-winter bolting resistance allele of BETA 1773. This result is an important milestone for breeding winter beets with complete bolting resistance after winter.

  16. A Detailed Analysis of the BR1 Locus Suggests a New Mechanism for Bolting after Winter in Sugar Beet (Beta vulgaris L.)

    Science.gov (United States)

    Tränkner, Conny; Lemnian, Ioana M.; Emrani, Nazgol; Pfeiffer, Nina; Tiwari, Surya P.; Kopisch-Obuch, Friedrich J.; Vogt, Sebastian H.; Müller, Andreas E.; Schilhabel, Markus; Jung, Christian; Grosse, Ivo

    2016-01-01

    Sugar beet (Beta vulgaris ssp. vulgaris) is a biennial, sucrose-storing plant, which is mainly cultivated as a spring crop and harvested in the vegetative stage before winter. For increasing beet yield, over-winter cultivation would be advantageous. However, bolting is induced after winter and drastically reduces yield. Thus, post-winter bolting control is essential for winter beet cultivation. To identify genetic factors controlling bolting after winter, a F2 population was previously developed by crossing the sugar beet accessions BETA 1773 with reduced bolting tendency and 93161P with complete bolting after winter. For a mapping-by-sequencing analysis, pools of 26 bolting-resistant and 297 bolting F2 plants were used. Thereby, a single continuous homozygous region of 103 kb was co-localized to the previously published BR1 QTL for post-winter bolting resistance (Pfeiffer et al., 2014). The BR1 locus was narrowed down to 11 candidate genes from which a homolog of the Arabidopsis CLEAVAGE AND POLYADENYLATION SPECIFICITY FACTOR 73-I (CPSF73-I) was identified as the most promising candidate. A 2 bp deletion within the BETA 1773 allele of BvCPSF73-Ia results in a truncated protein. However, the null allele of BvCPSF73-Ia might partially be compensated by a second BvCPSF73-Ib gene. This gene is located 954 bp upstream of BvCPSF73-Ia and could be responsible for the incomplete penetrance of the post-winter bolting resistance allele of BETA 1773. This result is an important milestone for breeding winter beets with complete bolting resistance after winter. PMID:27895650

  17. Enhanced independence: experiences after regaining grip function in people with tetraplegia.

    Science.gov (United States)

    Wangdell, Johanna; Carlsson, Gunnel; Fridén, Jan

    2013-01-01

    To explore how surgical reconstruction of grip affects everyday life for patients with tetraplegia, with special emphasis on patients perspective of their perceived changes. Qualitative method. Eleven people (aged 22-73) with tetraplegia who had undergone surgical reconstruction to restore grip function. Qualitative interviews were conducted 7-17 months after surgery and analysed using Grounded theory. The core concept describing the participants experienced gains after grip reconstructive surgery was "enhanced independence". It was associated with changes in both practical and psychological aspects of independence. Practical aspects identified were: "perform more activities", "smoother everyday life", "renewed ability to participate in social activities", "less dependence on assistance" and "less restricted by physical environment". Psychological aspects of independence included "regained privacy", "increased manageability", "regained identity", "recapture a part of the body" and "share positive experiences with relatives and friends". Encompassing all categories was the concept "self-efficacy in hand control". It was seen as a result included in the enhanced independency core but also as an important factor for the development of all the other categories. Participants in this study experienced enhanced independence after grip reconstructive surgery and rehabilitation. The enhanced independence included both practical and physical aspects and it influenced all domains using the International Classification of Function, Disability and Health model; body function and structure, activities, participation, personal factors and environmental factors. Implications for Rehabilitation Patients with tetraplegia experience grip reconstruction as a useful intervention, an enhanced independence, related to their improved hand control. The increased hand control impacted not only physical aspects but also practical and psychological aspects. It also influenced social and

  18. From regained function to daily use: experiences of surgical reconstruction of grip in people with tetraplegia.

    Science.gov (United States)

    Wangdell, Johanna; Carlsson, Gunnel; Friden, Jan

    2014-01-01

    To capture patients' relearning processes from regained function to improvements in daily life after grip reconstructive surgery in tetraplegia. Eleven people with tetraplegia who underwent grip reconstructive surgery during February 2009 to March 2011. Qualitative interviews were conducted 7 to 17 months after surgery and analysed using grounded theory. Determination to reach a higher level of independence was the core concept to integrate regained function into daily life. There were 3 phases identified; "Initiate activity training," "Establish hand control in daily activities," and "Challenge dependence." Between the phases psychological stages occurred, first; "a belief in improved ability", and later in the process; "confidence in ability". The process to fully integrate regain function in daily life was described as long and time-consuming. However, the participants claimed it useful to do the skills training in their home environment, without long-term in clinic rehabilitation. Relearning activities in daily life after a grip reconstruction is a time-consuming and demanding process. It includes skills training, mental strategies and psychological stages together with environmental and social factors. Accordingly, rehabilitation after grip reconstruction in tetraplegia should focus on both grip skills and psychological stages, to encourage that patient's keep their determination and achieve greater independence. Implications for Rehabilitation There is a stepwise process to transform improved function into daily use. The most important factor to transform improved function into daily use was motivation to reach a higher independence. Other important factors were; skills training, use of individual learning strategies, belief and confidence in personal ability, social and environmental factors. There was a long and demanding process to fully transform the improved function into daily use. The participants preferred to do activity training in the specific

  19. Modeling of the interaction between grip force and vibration transmissibility of a finger.

    Science.gov (United States)

    Wu, John Z; Welcome, Daniel E; McDowell, Thomas W; Xu, Xueyan S; Dong, Ren G

    2017-07-01

    It is known that the vibration characteristics of the fingers and hand and the level of grip action interacts when operating a power tool. In the current study, we developed a hybrid finger model to simulate the vibrations of the hand-finger system when gripping a vibrating handle covered with soft materials. The hybrid finger model combines the characteristics of conventional finite element (FE) models, multi-body musculoskeletal models, and lumped mass models. The distal, middle, and proximal finger segments were constructed using FE models, the finger segments were connected via three flexible joint linkages (i.e., distal interphalangeal joint (DIP), proximal interphalangeal joint (PIP), and metacarpophalangeal (MCP) joint), and the MCP joint was connected to the ground and handle via lumped parameter elements. The effects of the active muscle forces were accounted for via the joint moments. The bone, nail, and hard connective tissues were assumed to be linearly elastic whereas the soft tissues, which include the skin and subcutaneous tissues, were considered as hyperelastic and viscoelastic. The general trends of the model predictions agree well with the previous experimental measurements in that the resonant frequency increased from proximal to the middle and to the distal finger segments for the same grip force, that the resonant frequency tends to increase with increasing grip force for the same finger segment, especially for the distal segment, and that the magnitude of vibration transmissibility tends to increase with increasing grip force, especially for the proximal segment. The advantage of the proposed model over the traditional vibration models is that it can predict the local vibration behavior of the finger to a tissue level, while taking into account the effects of the active musculoskeletal force, the effects of the contact conditions on vibrations, the global vibration characteristics. Published by Elsevier Ltd.

  20. The properties and interrelationships of various force-time parameters during maximal repeated rhythmic grip.

    Science.gov (United States)

    Nakada, Masakatsu; Demura, Shinichi; Yamaji, Shunsuke

    2007-01-01

    The purpose of this study was to examine the properties and interrelationships of various force-time parameters including the inflection point for the rate of decline in force during a maximal repeated rhythmic grip. Fifteen healthy males (age M=21.5, SD=2.1 yr, height M=172.4, SD=5.7 cm, body mass M=68.2, SD=9.2 kg) participated in this study. Subjects performed a maximal repeated rhythmic grip with maximal effort with a target frequency of 30 grip.min(-1) for 6 min. The force value decreased linearly and markedly until about 70% of maximal strength for about 55 s after the onset of a maximal repeated rhythmic grip, and then decreased moderately. Because all parameters showed fair or good correlations between 3 min and 6 min, they are considered to be able to sufficiently evaluate muscle endurance for 3 min instead of 6 min. However, there were significant differences between 3 min and 6 min in the integrated area, the final force, the rate of the decrement constant (k) fitting the force decreasing data to y=ae(-kx)+b and the force of maximal difference between the force and a straight line from peak force to the final force. Their parameters may vary generally by the length of a steady state, namely, a measurement time. The final force value before finishing and the rate of the decrement constant (k) reflect the latter phase during a maximal repeated rhythmic grip. Although many parameters show relatively high mutual relationships, the rate constant (k) shows relatively low correlations with other parameters. We inferred that decreasing the time until 80% of maximal strength and the amount of the decrement force for the first 1 min reflect a linear decrease in the initial phase.

  1. Precision grip responses to unexpected rotational perturbations scale with axis of rotation.

    Science.gov (United States)

    De Gregorio, Michael; Santos, Veronica J

    2013-04-05

    It has been established that rapid, pulse-like increases in precision grip forces ("catch-up responses") are elicited by unexpected translational perturbations and that response latency and strength scale according to the direction of linear slip relative to the hand as well as gravity. To determine if catch-up responses are elicited by unexpected rotational perturbations and are strength-, axis-, and/or direction-dependent, we imposed step torque loads about each of two axes which were defined relative to the subject's hand: the distal-proximal axis away from and towards the subject's palm, and the grip axis which connects the two fingertips. Precision grip responses were dominated initially by passive mechanics and then by active, unimodal catch-up responses. First dorsal interosseous activity, marking the start of the catch-up response, began 71-89 ms after the onset of perturbation. The onset latency, shape, and duration (217-231 ms) of the catch-up response were not affected by the axis, direction, or magnitude of the rotational perturbation, while strength was scaled by axis of rotation and slip conditions. Rotations about the grip axis that tilted the object away from the palm and induced rotational slip elicited stronger catch-up responses than rotations about the distal-proximal axis that twisted the object between the digits. To our knowledge, this study is the first to investigate grip responses to unexpected torque loads and to show characteristic, yet axis-dependent, catch-up responses for conditions other than pure linear slip. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Quantum Friction in Different Regimes

    Science.gov (United States)

    Klatt, Juliane; Buhmann, Stefan

    2015-03-01

    Quantum friction is the velocity-dependent force between two polarizable objects in relative motion, resulting from field-fluctuation mediated transfer of energy and momentum between them. Due to its short-ranged nature it has proven difficult to observe experimentally. Theoretical attempts to determine the precise velocity-dependence of the quantum drag experienced by a polarizable atom moving parallel to a surface arrive at contradicting results. Scheel and Barton predict a force linear in relative velocity v - the former using the quantum regression theorem and the latter employing time-dependent perturbation theory. Intravaia, however, predicts a v3 power-law starting from a non-equilibrium fluctuation-dissipation theorem. In order to learn where exactly the above approaches part, we set out to perform all three calculations within one and the same framework: macroscopic QED. In addition, we include contributions to quantum friction from Doppler shift and Röntgen interaction, which play a role for perpendicular motion and retarded distances, respectively, and consider non-stationary states of atom and field. DFG Emmy-Noether Program.

  3. Mathematical models of viscous friction

    CERN Document Server

    Buttà, Paolo; Marchioro, Carlo

    2015-01-01

    In this monograph we present a review of a number of recent results on the motion of a classical body immersed in an infinitely extended medium and subjected to the action of an external force. We investigate this topic in the framework of mathematical physics by focusing mainly on the class of purely Hamiltonian systems, for which very few results are available. We discuss two cases: when the medium is a gas and when it is a fluid. In the first case, the aim is to obtain microscopic models of viscous friction. In the second, we seek to underline some non-trivial features of the motion. Far from giving a general survey on the subject, which is very rich and complex from both a phenomenological and theoretical point of view, we focus on some fairly simple models that can be studied rigorously, thus providing a first step towards a mathematical description of viscous friction. In some cases, we restrict ourselves to studying the problem at a heuristic level, or we present the main ideas, discussing only some as...

  4. Kozai Cycles and Tidal Friction

    Energy Technology Data Exchange (ETDEWEB)

    L, K; P.P., E

    2009-07-17

    Several studies in the last three years indicate that close binaries, i.e. those with periods of {approx}< 3 d, are very commonly found to have a third body in attendance. We argue that this proves that the third body is necessary in order to make the inner period so short, and further argue that the only reasonable explanation is that the third body causes shrinkage of the inner period, from perhaps a week or more to the current short period, by means of the combination of Kozai cycles and tidal friction (KCTF). In addition, once KCTF has produced a rather close binary, magnetic braking also combined with tidal friction (MBTF) can decrease the inner orbit further, to the formation of a contact binary or even a merged single star. Some of the products of KCTF that have been suggested, either by others or by us, are W UMa binaries, Blue Stragglers, X-ray active BY Dra stars, and short-period Algols. We also argue that some components of wide binaries are actually merged remnants of former close inner pairs. This may include such objects as rapidly rotating dwarfs (AB Dor, BO Mic) and some (but not all) Be stars.

  5. Low-friction nanojoint prototype

    Science.gov (United States)

    Vlassov, Sergei; Oras, Sven; Antsov, Mikk; Butikova, Jelena; Lõhmus, Rünno; Polyakov, Boris

    2018-05-01

    High surface energy of individual nanostructures leads to high adhesion and static friction that can completely hinder the operation of nanoscale systems with movable parts. For instance, silver or gold nanowires cannot be moved on silicon substrate without plastic deformation. In this paper, we experimentally demonstrate an operational prototype of a low-friction nanojoint. The movable part of the prototype is made either from a gold or silver nano-pin produced by laser-induced partial melting of silver and gold nanowires resulting in the formation of rounded bulbs on their ends. The nano-pin is then manipulated into the inverted pyramid (i-pyramids) specially etched in a Si wafer. Due to the small contact area, the nano-pin can be repeatedly tilted inside an i-pyramid as a rigid object without noticeable deformation. At the same time in the absence of external force the nanojoint is stable and preserves its position and tilt angle. Experiments are performed inside a scanning electron microscope and are supported by finite element method simulations.

  6. Gimbaled-shoulder friction stir welding tool

    Science.gov (United States)

    Carter, Robert W. (Inventor); Lawless, Kirby G. (Inventor)

    2010-01-01

    A gimbaled-shoulder friction stir welding tool includes a pin and first and second annular shoulders coupled to the pin. At least one of the annular shoulders is coupled to the pin for gimbaled motion with respect thereto as the tool is rotated by a friction stir welding apparatus.

  7. Advanced friction modeling in sheet metal forming

    NARCIS (Netherlands)

    Hol, J.; Cid Alfaro, M.V.; Meinders, Vincent T.; Huetink, Han

    2011-01-01

    The Coulomb friction model is frequently used for sheet metal forming simulations. This model incorporates a constant coefficient of friction and does not take the influence of important parameters such as contact pressure or deformation of the sheet material into account. This article presents a

  8. Friction tensor concept for textured surfaces

    Indian Academy of Sciences (India)

    This paper proposes the concept of a friction tensor analogous to the heat conduc- tion tensor in anisotropic media. This implies that there exists two principal friction coefficients μ1,2 analogous to the principal conductivities k1,2. For symmetrically textured surfaces the principal directions are orthogonal with atleast one ...

  9. Friction in textile thermoplastic composites forming

    NARCIS (Netherlands)

    Akkerman, Remko; ten Thije, R.H.W.; Sachs, Ulrich; de Rooij, Matthias B.; Binetruy, C.; Boussu, F.

    2010-01-01

    A previously developed mesoscopic friction model for glass/PP textile composite laminates during forming is evaluated for glass and carbon/PPS laminates, at higher temperatures and lower viscosities than before. Experiments were performed for tool/ply and ply/ply configurations in a new friction

  10. The role of friction in tow mechanics

    NARCIS (Netherlands)

    Cornelissen, Bo

    2013-01-01

    Friction plays and important role in the processing of fibrous materials: during production of tow materials, during textile manufacturing and during preforming operations for composite moulding processes. One of the poorly understood phenomena in these processes is the dynamic frictional behaviour

  11. Friction Coefficient Determination by Electrical Resistance Measurements

    Science.gov (United States)

    Tunyagi, A.; Kandrai, K.; Fülöp, Z.; Kapusi, Z.; Simon, A.

    2018-01-01

    A simple and low-cost, DIY-type, Arduino-driven experiment is presented for the study of friction and measurement of the friction coefficient, using a conductive rubber cord as a force sensor. It is proposed for high-school or college/university-level students. We strongly believe that it is worthwhile planning, designing and performing Arduino…

  12. Prediction of friction coefficients for gases

    Science.gov (United States)

    Taylor, M. F.

    1969-01-01

    Empirical relations are used for correlating laminar and turbulent friction coefficients for gases, with large variations in the physical properties, flowing through smooth tubes. These relations have been used to correlate friction coefficients for hydrogen, helium, nitrogen, carbon dioxide and air.

  13. Position-dependent friction in quantum mechanics

    International Nuclear Information System (INIS)

    Srokowski, T.

    1985-01-01

    The quantum description of motion of a particle subjected to position-dependent frictional forces is presented. The two cases are taken into account: a motion without external forces and in the harmonic oscillator field. As an example, a frictional barrier penetration is considered. 16 refs. (author)

  14. Device measures static friction of magnetic tape

    Science.gov (United States)

    Cole, P. T.

    1967-01-01

    Device measures the coefficient of static friction of magnetic tape over a range of temperatures and relative humidities. It uses a strain gage to measure the force of friction between a reference surface and the tape drawn at a constant velocity of approximately 0.0001 inch per second relative to the reference surface.

  15. Friction tensor concept for textured surfaces

    Indian Academy of Sciences (India)

    friction coefficients of Mg and Al-Mg alloy pins sliding over EN8 steel flats. The sliding angle was varied between 0 and 90 degrees and morphology of ... has explained friction based on energy dissipation mechanisms initiated in the early history of tribology by Rabinowicz (1951). Despite the spatio-temporal complexity in ...

  16. Frictional systems under periodic loads — History-dependence, non-uniqueness and energy dissipation

    International Nuclear Information System (INIS)

    Barber, J R

    2012-01-01

    Nominally static contacts such as bolted or shrink-fit joints typically experience regions of microslip when subjected to oscillatory loading. This results in energy dissipation, reflected as apparent hysteretic damping of the system, and also may cause the initiation of fretting fatigue cracks. Early theoretical studies of the Hertzian contact problem by Cattaneo and Mindlin were confirmed experimentally by Johnson, who identified signs of fretting damage in the slip annulus predicted by the theory. For many years, tribologists assumed that Melan's theorem in plasticity could be extended to frictional systems — i.e. that if there exists a state of residual stress associated with frictional slip that is sufficient to prevent periodic slip in the steady state, then the system will shake down, regardless of the initial condition. However, we now know that this is true only if there is no coupling between the normal and tangential loading problems, as will be the case notably when contact occurs on a symmetry plane. For all other cases, periodic loading scenarios can be devised such that shakedown occurs for some initial conditions and not for others. The initial condition here might be determined by the assembly protocol — e.g. the order in which a set of bolts is tightened — or by the exact loading path before the steady cycle is attained. This non-uniqueness of the steady state persists at load amplitudes above the shakedown limit, in which case there is always some dissipation, but the dissipation per cycle (and hence both the effective damping and the susceptibility to fretting damage) depends on the initial conditions. This implies that fretting fatigue experiments need to follow a well-defined assembly protocol if reproducible results are to be obtained. We shall also present results showing that when both normal and tangential forces vary in time, the energy dissipation is very sensitive to the relative phase of the oscillatory components, being greatest

  17. Trial manufacture of rotary friction tester and frictional force measurement of metals

    CERN Document Server

    Abe, T; Kanari, M; Tanzawa, S

    2002-01-01

    In the plasma confinement type fusion reactor, in-vessel structures such as a blanket module slide at the joints each other when plasma disruption occurs, and then frictional heat is generated there. Therefore, for the selection of material and the use as the design data, it is important to understand the frictional characteristics of metals and ceramic films in the vacuum. In the present study, we have manufactured a prototype of rotary friction tester and examined the performances of the tester. The frictional characteristics of metals in the room air was measured using the friction tester, and the results obtained are as follows. A drifting friction force for a constant time and a friction force during the idling were 98 mN and 225 mN, respectively. These values were sufficiently small as compared to pressing load (9.8 - 57.8 N) used in the friction test. In a friction force measurement of stainless steel, dynamic friction force obeyed Amontons' law which indicated that dynamic friction force is not depend...

  18. Novel friction law for the static friction force based on local precursor slipping.

    Science.gov (United States)

    Katano, Yu; Nakano, Ken; Otsuki, Michio; Matsukawa, Hiroshi

    2014-09-10

    The sliding of a solid object on a solid substrate requires a shear force that is larger than the maximum static friction force. It is commonly believed that the maximum static friction force is proportional to the loading force and does not depend on the apparent contact area. The ratio of the maximum static friction force to the loading force is called the static friction coefficient µM, which is considered to be a constant. Here, we conduct experiments demonstrating that the static friction force of a slider on a substrate follows a novel friction law under certain conditions. The magnitude of µM decreases as the loading force increases or as the apparent contact area decreases. This behavior is caused by the slip of local precursors before the onset of bulk sliding and is consistent with recent theory. The results of this study will develop novel methods for static friction control.

  19. The ITER EC H and CD upper launcher: Design, analysis and testing of a bolted joint for the Blanket Shield Module

    Energy Technology Data Exchange (ETDEWEB)

    Gessner, Robby, E-mail: robby.gessner@kit.edu [Karlsruhe Institute of Technology, Institute for Applied Materials, P.O. Box 3640, D-76021 Karlsruhe (Germany); Aiello, Gaetano; Grossetti, Giovanni; Meier, Andreas [Karlsruhe Institute of Technology, Institute for Applied Materials, P.O. Box 3640, D-76021 Karlsruhe (Germany); Ronden, Dennis [DIFFER – Dutch Institute for Fundamental Energy Physics, P.O. Box 1207, NL-3430 BE Nieuwegein (Netherlands); Spaeh, Peter; Scherer, Theo; Schreck, Sabine; Strauss, Dirk; Vaccaro, Alessandro [Karlsruhe Institute of Technology, Institute for Applied Materials, P.O. Box 3640, D-76021 Karlsruhe (Germany)

    2013-10-15

    Highlights: ► The BSM of the ECH Launcher is attached to the Launcher Main Frame by a bolted joint. ► The bolts were designed as “captive” in order to avoid their accidental removal from the joint. ► The bolted flange connection using two sets of 15 captive bolts (M22 × 2) placed along the sides. ► The captive bolt design is based on a concept that uses a dedicated spring ring, a standard spiral spring and a tensioning screw with two threads to secure the bolts in a form-locking stop. -- Abstract: The final design of the structural system for the ITER EC H and CD upper launcher is in progress. Many design features of the preliminary design are under revision with the aim to achieve the built-to-print-status. This paper deals with design and analysis of a bolted joint for the Blanket Shield Module with special perspective on Remote Handling capability. The BSM of the ECH Launcher is attached to the Launcher Main Frame by a bolted joint conceived so that in the Hot Cell Facility, RH maintenance can be performed on internal components. The joint must be capable to resist very high Electro-Magnetic loads from disruptions, while it has to sustain substantial thermal cycling during operation. Thus the need for a rigid and reliable design is essential. Beside the set of pre-stressed bolts the flanges were therefore equipped with additional shear keys to divert radial moments away from the bolts. Main focus of the work performed was the mechanical design of the joint and the assessment of the structural integrity with respect to the loads applied and its capability for maintenance by RH procedures. To fulfill a major aspect of the RH requirements, the bolts were designed as “captive” in order to avoid their accidental removal from the joint. The captive bolt design is based on a concept that uses a dedicated spring ring, a standard spiral spring and a tensioning screw with two threads to secure the bolts in a form-locking stop. The final approval phase of

  20. Selective Linear-Regression Model for hand posture discrimination and grip force estimation using surface electromyogram signals.

    Science.gov (United States)

    Yamanoi, Yusuke; Morishita, Soichiro; Kato, Ryu; Yokoi, Hiroshi

    2015-01-01

    This paper proposes the method of hand posture discrimination and grip force estimation by means of Selective Linear-Regression Model. Generally, myoelectric hands which discriminate hand posture and estimate grip force at the same time result in unsatisfying results because of complication of EMG signals. Therefore, most of myoelectric hands can control either the force or the posture. However, the proposed method is able to discriminate hand posture and to estimate grip force simultaneously while the accuracy results are achieved. In experiments, EMG signals were measured while hand posture and grip force were changing. As a result, it appears that EMG features increase monotonically with grip force. In addition, increasing forms of EMG features are different on each posture. Based on these experimental results, the authors propose the method for both discriminating hand posture and estimating grip force by means of several linear-regression models which utilize the relationship between the grip force and EMG features on each posture. To evaluate the effectiveness of this method, the failure rates of discrimination and the estimation errors of the proposed method were employed. The results indicate that failure rates and estimation errors are improved significantly.