WorldWideScience

Sample records for frictional losses evaluation

  1. Numerical and Experimental Study of Friction Loss in Hydrostatic Motor

    DEFF Research Database (Denmark)

    Sørensen, Rasmus Mørk; Hansen, Michael R.; Mouritsen, Ole Ø.

    2012-01-01

    This paper presents a numerical and experimental study of the losses in a hydrostatic motor principle. The motor is designed so that the structural de ections and lubricating regimes between moving surfaces and, subsequently, the leakage and friction losses, can be controlled during operation....... This is done by means of additional pressure volumes that in uence the stator de ection. These pressures are referred to as compensation pressures and the main emphasis is on friction or torque loss modeling of the motor as a function of the compensation pressures and the high and low pressures related...... to the load torque. The torque loss modeling is identied as a Stribeck curve which depends on gap height. The asperity friction is decreasing exponentially with an increase in gap height. The parameters of the torque loss model are based on prototype measurements that include the structural de ections...

  2. Analysis of Apex Seal Friction Power Loss in Rotary Engines

    Science.gov (United States)

    Handschuh, Robert F.; Owen, A. Karl

    2010-01-01

    An analysis of the frictional losses from the apex seals in a rotary engine was developed. The modeling was initiated with a kinematic analysis of the rotary engine. Next a modern internal combustion engine analysis code was altered for use in a rotary engine to allow the calculation of the internal combustion pressure as a function of rotor rotation. Finally the forces from the spring, inertial, and combustion pressure on the seal were combined to provide the frictional horsepower assessment.

  3. On the mechanical friction losses occurring in automotive differential gearboxes.

    Science.gov (United States)

    Antoni, Grégory

    2014-01-01

    In the automobile industry, the mechanical losses resulting from friction are largely responsible for various kinds of surface damage, such as the scuffing occurring in some mechanical assemblies. These scuffing processes seem to be due to a local loss of lubrication between certain mechanical elements of the same assembly, leading to a sharp increase in the friction, which can lead to a surface and volume damage in some of them, and even can cause, in the worst case, the whole destruction of the mechanical system if it has continued to operate. Predicting and checking the occurrence of this kind of undesirable phenomena, especially in some principal systems of the vehicle, represents nowadays, a crucial challenge in terms of automobile reliability and safety. This study focuses on the mechanical friction losses liable to occur in differential automobile gearboxes, which can lead in the long term to the scuffing of these mechanical systems. The friction losses involved were modeled, using a simple analytical approach, which is presented and discussed.

  4. Estimating head and frictional losses through pipe fittings in building ...

    African Journals Online (AJOL)

    By extending pipe length by equal increments, with corresponding increments in number of sanitary appliances and total water flow rates to a water distribution system of a building, fractions of the total frictional loss throu-gh pipe fittings for varying work complexities were obtained. The fractions varied from 0.342 to 0.377 as ...

  5. 3D Simulation of a Loss of Vacuum Accident (LOVA in ITER (International Thermonuclear Experimental Reactor: Evaluation of Static Pressure, Mach Number, and Friction Velocity

    Directory of Open Access Journals (Sweden)

    Jean-François Ciparisse

    2018-04-01

    Full Text Available ITER (International Thermonuclear Experimental Reactor is a magnetically confined plasma nuclear reactor. Inside it, due to plasma disruptions, the formation of neutron-activated powders, which are essentially made out of tungsten and beryllium, occurs. As many windows for diagnostics are present on the reactor, which operates at very low pressure, a LOVA (Loss of Vacuum Accident could be possible and may lead to dust mobilisation and a toxic and radioactive fallout inside the plant. This study is aimed at reproducing numerically the first seconds of a LOVA in ITER, in order to get information about the dust resuspension risk. This work has been carried out by means of a CFD (Computational Fluid Dynamics simulation of the beginning of the pressurisation transient inside the whole Tokamak. It has been found that the pressurization transient is extremely slow, and that the friction speed on the walls is very high, and therefore a high mobilization risk of the dust is expected on the entire internal surface of the reactor. It has been observed that a LOVA in a real-scale reactor is more severe than the one reproduced in reduced-scale facilities, as STARDUST-U, because the speeds are higher, and the dust resuspension capacity of the flow is greater.

  6. Tribo-performance evaluation of ecofriendly brake friction composite materials

    Science.gov (United States)

    Kumar, Naresh; Singh, Tej; Grewal, G. S.

    2018-05-01

    This paper presents the potential of natural fibre in brake friction materials. Natural fibre filled ecofriendly brake friction materials were developed without Kevlar fibre evaluated for tribo-performance on a chase friction testing machine following SAE J 661a standard. Experimental results indicated that natural fibre enhances the fade performance, but depresses the friction and wear performance, whereas Kevlar fibre improves the friction, wear and recovery performance but depresses the fade performance. Also the results revealed that with the increase in natural fibre content, the friction and fade performances enhanced.

  7. Design, Construction, and Evaluation of Rubber Friction Tester

    Directory of Open Access Journals (Sweden)

    Mehdi Razzaghi Kashani

    2012-12-01

    Full Text Available Coeffcient of  friction  (COF  for  rubber parts  is one of  the key parameters in their interaction with solid rough surfaces (micrometer to millimeter scales,  such  as  tire-road  interactions. COF  of  rubber  depends  on  viscoelastic properties of rubber, roughness characteristics of the counter-part surface, and process variables such as contact nominal pressure and sliding speed. Due to the need for measuring COF  for  rubber,  a  new  friction  tester, with  continuous  variation  of nominal pressure and sliding speed, was designed and constructed in order to assess the effect of above mentioned parameters. Tire tread compounds, as the most common rubber part  in  the feld of  rubber  tribology, was used  for  this purpose. Viscoelastic properties of compounds were varied by changing composition of styrene-butadiene rubber (SBR and butadiene rubber (BR in the blend. Effect of surface roughness was evaluated by using silicon-carbide papers with different roughness parameters. By statistical analysis it was shown that the designed friction tester has high accuracy in measuring the coeffcient of friction of rubber and differentiating the effective parameters. Increasing the nominal pressure led to reduction of COF and increase in sliding speed forced it through a maximum. In conclusion, the loss factor of the compound and asymmetry in roughness distribution of the counter-surface are considered as the most effective parameters on COF of rubber.

  8. Measurement and Calculation of Frictional Loss in Large Two-Stroke Engines

    DEFF Research Database (Denmark)

    Vølund, Anders

    2003-01-01

    The total frictional loss in a large two-stroke marine diesel engine is rather well determined. However, the contribution (size and distribution) from the different machine elements are not well known. The aim of this study is to establish methods to measure and calculate friction in the piston...... assembly and guide shoe system for a large two-stroke marine diesel engine. These components are the two major contributors to the total friction in a two-stroke marine diesel engine. The piston pack represents approximately 60% of the total mechanical loss at full load and the guide shoe system 23...

  9. 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

  10. Influence of various base oils on friction and power loss in gears; Einfluss verschiedener Grundoele auf Reibung und Verlustleistung in Zahnradgetrieben

    Energy Technology Data Exchange (ETDEWEB)

    Doleschel, A.; Michaelis, K.; Hoehn, B.R.

    2001-03-01

    The frictional behaviour of synthetic lubricants was systematically investigated in a twin disc test rig and a back-to-back gear test rig. For 22 lubricants (mineral oil, polyalfaolefin (PAO), polyglycol (PG), ester and mixtures) the coefficient of friction was measured in the twin disc test rig, dependant on pressure, oil temperature, rolling and sliding velocity. In the gear test rig pressure and velocity was varied for 9 lubricants. The mineral oil shows an estimated coefficient of friction of about {mu} >> 0.045, the synthetic lubricants have a lower coefficient of friction. In the twin disc test rig the lowest coefficient of friction with PG as low as 20% of the coefficient of mineral oil was measured, depending on the mixture of EO:PO. In the gear test rig such low coefficients of friction were not measured, but still values of 60% compared to mineral oil were obtained. Esters show in the twin disc test rig a coefficient of friction in the range of 30% to 100% of the coefficient of friction of mineral oil, in the gear test rig in the range of 60% to 100%. From these investigations a calculation method for the coefficient of friction in disc and gear contacts was derived. With these equations the power loss and efficiency of transmissions in practice, lubricated with synthetic gear oils can be evaluated. (orig.)

  11. Cuttings-liquid frictional pressure loss model for horizontal narrow annular flow with rotating drillpipe

    International Nuclear Information System (INIS)

    Ofei, T N; Irawan, S; Pao, W

    2015-01-01

    During oil and gas drilling operations, frictional pressure loss is experienced as the drilling fluid transports the drilled cuttings from the bottom-hole, through the annulus, to the surface. Estimation of these pressure losses is critical when designing the drilling hydraulic program. Two-phase frictional pressure loss in the annulus is very difficult to predict, and even more complex when there is drillpipe rotation. Accurate prediction will ensure that the correct equivalent circulating density (ECD) is applied in the wellbore to prevent formation fracture, especially in formations with narrow window between the pore pressure and fracture gradient. Few researchers have attempted to propose cuttings-liquid frictional pressure loss models, nevertheless, these models fail when they are applied to narrow wellbores such as in casing- while-drilling and slimhole applications. This study proposes improved cuttings-liquid frictional pressure loss models for narrow horizontal annuli with drillpipe rotation using Dimensional Analysis. Both Newtonian and non-Newtonian fluids were considered. The proposed model constants were fitted by generated data from a full-scale simulation study using ANSYS-CFX. The models showed improvement over existing cuttings-liquid pressure loss correlations in literature. (paper)

  12. [Evaluation of orthodontic friction using a tribometer with alternating movement].

    Science.gov (United States)

    Pernier, C M; Jablonska-Mazanek, E D; Ponsonnet, L; Grosgogeat, B

    2005-12-01

    It is essential for orthodontists to control the complex phenomenon of friction. The in vitro techniques, usually dynamometers or tensile testing machines, used to measure the frictional resistance between arch wires and brackets are linear and unidirectional and can be criticised because tooth movements, such as tipping and uprighting, as well everyday oral activities, primarily chewing, are not uni-dimensional but more closely resemble the small amplitude oscillatory phenomena known as fretting. We therefore decided to develop a fretting machine not with linear but with alternating movements better suited to evaluate the frictional behaviour of orthodontic bracket-wire combinations. Once we had completed construction of this device, we proceeded to measure the frictional resistance between one stainless steel bracket (MicroArch GAC) and five wires currently used in orthodontics (Two nickel-titanium shape memory alloys: Neo Sentalloy and Neo Sentalloy with Ionguard GAC--Three titanium-molybdenum alloys: TMA and Low Friction TMA Ormco and Resolve GAC). We were able to set up a classification of the wires according to their coefficient of friction, demonstrating the inefficacy of ion implantation and quantifying the increase in the coefficient of friction which occurs when Resolve wires are placed in the oral environment for approximately one year.

  13. A research on determining the friction losses formed in the small ...

    African Journals Online (AJOL)

    fastest way is to make use of the values given in the tables or diagrams determined by the equation of Hazen-Williams. However, no data related to floppy polythene (PE) pipes with small diameter is available in the tables and diagrams mentioned. In this study, values relating to friction losses and pressures formed in 10, 20, ...

  14. Evaluation of frictional forces of polycarbonate self-ligating brackets.

    Science.gov (United States)

    Fernandes, Daniel J; Miguel, José Augusto M; Quintão, Catia C A; Elias, Carlos N

    2010-01-01

    To evaluate the frictional forces generated by ceramic- (Opal, Ultradent) and glass-fiber-reinforced polycarbonate self-ligating brackets (Oyster, Gestenco) and compare the effectiveness of these ligatureless systems with glass-fiber-reinforced polycarbonate conventional brackets (Blonde, Gestenco). The hypothesis is that there is no difference between frictional forces generated by ceramic- and glass-fiber-reinforced polycarbonate self-ligating and glass-fiber-reinforced polycarbonate conventional brackets. Twelve preadjusted 0.022 3 0.028-inch maxillary canine brackets were tested, divided into three groups: Opal, Oyster, and Blonde. Frictional tests were conducted with the Emic DL 10000 testing machine with a 20 N loadcell for 40 seconds at a 0.5 cm/min speed. Each bracket-wire combination was tested five times. The data generated were analyzed by parametric analysis of variance (one-way ANOVA) and Bonferroni tests. Analysis of variance indicated significant differences for the three groups (Pfrictional forces of the Oyster glass-fiber-reinforced polycarbonate self-ligating brackets were significantly lower (37.0 ± 8.9 cN) than those of the Opal ceramic-reinforced polycarbonate self-ligating brackets (49.5 ± 10.1 cN), while the Blonde glass-fiber-reinforced conventional bracket frictional forces were 105.8 ± 6.4 cN. Oyster glass-fiber-reinforced polycarbonate brackets produced less friction than Opal ceramic-reinforced polycarbonate brackets. The polycarbonate ligatureless system showed significantly lower frictional forces compared to Blonde conventional polycarbonate brackets tied with elastomeric ligatures. The study rejected the initial hypothesis because there are significant differences of frictional forces among the tested systems. © 2010 BY QUINTESSENCE PUBLISHING CO, INC.

  15. Evaluation of coefficient of friction in bulk metal forming

    NARCIS (Netherlands)

    Solhjoo, Soheil

    In this study an upper bound analysis for cylindrical "Barrel Compression Test" (BCT) is developed. BCT method is a very simple method which can be utilized in order to evaluate quantitatively the coefficient of friction by means of just one cylindrical specimen in an upsetting test. The method is

  16. Analysis of the Journal Bearing Friction Losses in a Heavy-Duty Diesel Engine

    Directory of Open Access Journals (Sweden)

    Christoph Knauder

    2015-04-01

    Full Text Available Internal combustion engines (ICE for the use in heavy-duty trucks and buses have to fulfil demanding requirements for both vehicle efficiency as well as for emission of greenhouse gases. Beside the piston assembly the journal bearings are among the largest contributors to friction in the ICE. Through a combination of measurements and validated simulation methods the journal bearing friction losses of a state-of-the-art heavy-duty Diesel engine are investigated for a large range of real world operating conditions. To this task recently developed and extensively validated simulation methods are used together with realistic lubricant models that consider the Non-Newtonian behaviour as well as the piezoviscous effect. In addition, the potential for further friction reduction with the use of ultra-low viscosity lubricants is explored. The results reveal a potential of about 8% friction reduction in the journal bearings using a 0W20 ultra-low viscosity oil with an HTHS-viscosity (The HTHS-viscosity is defined as the dynamic viscosity of the lubricant measured at 150 °C and at a shear rate of 106 s

  17. Evaluation of Skin Friction Drag for Liner Applications in Aircraft

    Science.gov (United States)

    Gerhold, Carl H.; Brown, Martha C.; Jasinski, Christopher M.

    2016-01-01

    A parameter that is gaining significance in the evaluation of acoustic liner performance is the skin friction drag induced by air flow over the liner surface. Estimates vary widely regarding the amount of drag the liner induces relative to a smooth wall, from less than a 20% increase to nearly 100%, and parameters such as face sheet perforate hole diameter, percent open area, and sheet thickness are expected to figure prominently in the skin friction drag. Even a small increase in liner drag can impose an economic penalty, and current research is focused on developing 'low drag' liner concepts, with the goal being to approach the skin friction drag of a smooth wall. The issue of skin friction drag takes on greater significance as airframe designers investigate the feasibility of putting sound absorbing liners on the non-lifting surfaces of the wings and fuselage, for the purpose of reducing engine noise reflected and scattered toward observers on the ground. Researchers at the NASA Langley Research Center have embarked on investigations of liner skin friction drag with the aims of: developing a systematic drag measurement capability, establishing the drag of current liners, and developing liners that produce reduced drag without compromising acoustic performance. This paper discusses the experimental procedures that have been developed to calculate the drag coefficient based on the change in momentum thickness and the companion research program being carried out to measure the drag directly using a force balance. Liner samples that are evaluated include a solid wall with known roughness and conventional liners with perforated facesheets of varying hole diameter and percent open area.

  18. The impact of microgeometry pistons with a stepped bearing surface for the friction loss of the internal combustion engine

    Directory of Open Access Journals (Sweden)

    Wroblewski Emil

    2017-01-01

    Full Text Available This paper present the results of experimental piston friction losses on stepped bearing surface microgeometry obtained on the test rig. This test rig is equipped with special temperature control system, which provides better stability to temperature than in standard systems. The results of station tests was discussed. Tests was analyzed depending the moment caused by the friction on the oil temperature in the oil sump. Specified conclusions allow to assess the impact of the stepped profile of the pistons bearing surface microgeometry for different values of engine speed and the oil temperature at the friction losses in the main kinematic engine node which is piston-cylinder.

  19. Evaluation of coefficient of friction in bulk metal forming

    OpenAIRE

    Solhjoo, Soheil

    2014-01-01

    In this study an upper bound analysis for cylindrical "Barrel Compression Test" (BCT) is developed. BCT method is a very simple method which can be utilized in order to evaluate quantitatively the coefficient of friction by means of just one cylindrical specimen in an upsetting test. The method is checked by a series of finite element method (FEM) simulations and by means of the results of FEM simulations the method is modified.

  20. Study of force loss due to friction comparing two ceramic brackets during sliding tooth movement.

    Science.gov (United States)

    AlSubaie, Mai; Talic, Nabeel; Khawatmi, Said; Alobeid, Ahmad; Bourauel, Christoph; El-Bialy, Tarek

    2016-09-01

    To compare the percentage of force loss generated during canine sliding movements in newly introduced ceramic brackets with metal brackets. Two types of ceramic brackets, namely polycrystalline alumina (PCA) ceramic brackets (Clarity Advanced) and monocrystalline alumina (MCA) ceramic brackets (Inspire Ice) were compared with stainless steel (SS) brackets (Victory Series). All bracket groups (n = 5 each) were for the maxillary canines and had a 0.018-inch slot size. The brackets were mounted on an Orthodontic Measurement and Simulation System (OMSS) to simulate the canine retraction movement into the first premolar extraction space. Using elastic ligatures, 0.016 × 0.022″ (0.40 × 0.56 mm) stainless steel archwires were ligated onto the brackets. Retraction force was applied via a nickel-titanium coil spring with a nearly constant force of approximately 1 N. The OMSS measured the percentage of force loss over the retraction path by referring to the difference between the applied retraction force and actual force acting on each bracket. Between group comparisons were done with one-way analysis of variance. The metal brackets revealed the lowest percentage of force loss due to friction, followed by the PCA and MCA ceramic bracket groups (67 ± 4, 68 ± 7, and 76 ± 3 %, respectively). There was no significant difference between SS and PCA brackets (p = 0.97), but we did observe significant differences between metal and MCA brackets (p = 0.03) and between PCA and MCA ceramic brackets (p = 0.04). PCA ceramic brackets, whose slot surface is covered with an yttria-stabilized zirconia-based coating exhibited frictional properties similar to those of metal brackets. Frictional resistance resulted in an over 60 % loss of the applied force due to the use of elastic ligatures.

  1. A method for evaluating dynamical friction in linear ball bearings.

    Science.gov (United States)

    Fujii, Yusaku; Maru, Koichi; Jin, Tao; Yupapin, Preecha P; Mitatha, Somsak

    2010-01-01

    A method is proposed for evaluating the dynamical friction of linear bearings, whose motion is not perfectly linear due to some play in its internal mechanism. In this method, the moving part of a linear bearing is made to move freely, and the force acting on the moving part is measured as the inertial force given by the product of its mass and the acceleration of its centre of gravity. To evaluate the acceleration of its centre of gravity, the acceleration of two different points on it is measured using a dual-axis optical interferometer.

  2. Numerical Simulation for Frictional Loss and Local Loss of a 5*5 SMART Rod Bundle

    International Nuclear Information System (INIS)

    Park, Jong-Pil; Kim, Seong Jin; Kwon, Hyuk; Seo, Kyong-Won; Hwang, Dae-Hyun

    2014-01-01

    The results showed good agreement with experimental data and/or reasonable values. However, these results were dependent on computational meshes and turbulence models and it still remains important issues in CFD analysis. The aim of present work is to assess the pressure drop in a 5*5 SMART rod bundle using 3D CFD code with various computational meshes and turbulence models. In the present work, 3D CFD code was utilized to investigate pressure drop in a SMART 5*5 rod bundle. The predicted pressure drop was strongly dependent with computational meshes and turbulence models. Based on CFD results in this study, least five of six meshes within the subchannel gap are required to get reliable result which is insensitive to the number of meshes. The friction factor predicted by k - ε model is good agreement with McAdams's correlation while SST model overestimate McAdams's correlation. However, it is difficult to judge performance of turbulence model because of lock of experimental data for a 5*5 SMART bare rod bundle. For nominal condition (Re-194,000) of SMART, SST model predict k-factor of MV and IFM grid as 1.304 and 0.748, respectively. This value is reasonable as compared with designed k-factor, 1.320 and 0.78

  3. Productivity Losses Associated with Head and Neck Cancer Using the Human Capital and Friction Cost Approaches.

    Science.gov (United States)

    Pearce, Alison M; Hanly, Paul; Timmons, Aileen; Walsh, Paul M; O'Neill, Ciaran; O'Sullivan, Eleanor; Gooberman-Hill, Rachael; Thomas, Audrey Alforque; Gallagher, Pamela; Sharp, Linda

    2015-08-01

    Previous studies suggest that productivity losses associated with head and neck cancer (HNC) are higher than in other cancers. These studies have only assessed a single aspect of productivity loss, such as temporary absenteeism or premature mortality, and have only used the Human Capital Approach (HCA). The Friction Cost Approach (FCA) is increasingly recommended, although has not previously been used to assess lost production from HNC. The aim of this study was to estimate the lost productivity associated with HNC due to different types of absenteeism and premature mortality, using both the HCA and FCA. Survey data on employment status were collected from 251 HNC survivors in Ireland and combined with population-level survival estimates and national wage data. The cost of temporary and permanent time off work, reduced working hours and premature mortality using both the HCA and FCA were calculated. Estimated total productivity losses per employed person of working age were EUR253,800 using HCA and EUR6800 using FCA. The main driver of HCA costs was premature mortality (38% of total) while for FCA it was temporary time off (73% of total). The productivity losses associated with head and neck cancer are substantial, and return to work assistance could form an important part of rehabilitation. Use of both the HCA and FCA approaches allowed different drivers of productivity losses to be identified, due to the different assumptions of the two methods. For future estimates of productivity losses, the use of both approaches may be pragmatic.

  4. Performance evaluation for darcy friction factor formulae using ...

    African Journals Online (AJOL)

    It is concluded that Newton Raphson ; Prandtl and Nikurdse; Zingrang and Sylvester ; Serghide ; Barr; Swamee and Jain; Eck ; Haaland ; Brkic ; Wood and Moody are first choice friction formulae based on the values of model of selection criterion. Keywords: Darcy Friction Factor, Pipe Flow, Statistical Methods, Darcy Friction ...

  5. Rational Design of Spur Gears Directed to Increase Efficiency and Decrease Loss by Friction

    OpenAIRE

    Gonzalo González Rey; Alejandra García Toll; María Eugenia García Domínguez

    2010-01-01

    External parallel-axis cylindrical gears are considered as very efficient means for transmitting mechanical power, but for requirements of maximum efficiency in the current machines and equipments a precision in the procedures of calculation of power losses is necessary. In this sense, the Technical Report ISO / TR 14179-1:2001 offers formulas with empirical and theoretical bases to evaluate the gear efficiency considering gear mesh losses, windage and churning losses, and losses by bearings ...

  6. Rotordynamic and Friction Loss Measurements on a High Speed Laval Rotor Supported by Floating Ring Bearings

    Directory of Open Access Journals (Sweden)

    Rob Eling

    2017-03-01

    Full Text Available Floating ring bearings are the commonly used type of bearing for automotive turbochargers. The automotive industry continuously investigates how to reduce the bearing friction losses and how to create silent turbochargers. Many of these studies involve creating a numerical model of the rotor-bearing system and performing validation on a test bench on which a turbocharger is driven by hot gases. This approach, however, involves many uncertainties which diminish the validity of the measurement results. In this study, we present a test setup in which these uncertainties are minimized. The measurement results show the behavior of the floating ring bearing as a function of oil feed pressure, oil feed temperature, rotor unbalance and bearing clearances. Next to an increased validity, the test setup provides measurement data with good repeatability and can therefore represent a case study which can be used for validation of rotor-bearing models.

  7. Evaluation of deep drawing force under different friction conditions

    Directory of Open Access Journals (Sweden)

    Lăzărescu Lucian

    2017-01-01

    Full Text Available The purpose of this study is to investigate the variation of the required punch load during the deep drawing process under different friction conditions. In this regards, several deep-drawing tests of cylindrical cups were conducted under four friction conditions at the tool–blank interface. The first case was the dry deep-drawing, considered as a reference friction condition, while in the other three cases hydraulic oil, lithium-based grease and animal fat were used as lubricants. For each friction case, three levels of blank holding force were adopted, namely 10, 20 and 25 kN. The finite element simulation of the deep-drawing process was used to generate a set of calibration curves. By overlapping the experimental load-stroke curves on the calibration curves, the friction coefficient was estimated for each friction case.

  8. Effects of heat loss as percentage of fuel's energy, friction and variable specific heats of working fluid on performance of air standard Otto cycle

    International Nuclear Information System (INIS)

    Lin, J.-C.; Hou, S.-S.

    2008-01-01

    The objective of this study is to analyze the effects of heat loss characterized by a percentage of the fuel's energy, friction and variable specific heats of working fluid on the performance of an air standard Otto cycle with a restriction of maximum cycle temperature. A more realistic and precise relationship between the fuel's chemical energy and the heat leakage that is based on a pair of inequalities is derived through the resulting temperature. The variations in power output and thermal efficiency with compression ratio, and the relations between the power output and the thermal efficiency of the cycle are presented. The results show that the power output as well as the efficiency where maximum power output occurs will increase with increase of the maximum cycle temperature. The temperature dependent specific heats of the working fluid have a significant influence on the performance. The power output and the working range of the cycle increase with the increase of specific heats of the working fluid, while the efficiency decreases with the increase of specific heats of the working fluid. The friction loss has a negative effect on the performance. Therefore, the power output and efficiency of the cycle decrease with increasing friction loss. It is noteworthy that the effects of heat loss characterized by a percentage of the fuel's energy, friction and variable specific heats of the working fluid on the performance of an Otto cycle engine are significant and should be considered in practical cycle analysis. The results obtained in the present study are of importance to provide good guidance for performance evaluation and improvement of practical Otto engines

  9. Psychophysical evaluation of a variable friction tactile interface

    Science.gov (United States)

    Samur, Evren; Colgate, J. Edward; Peshkin, Michael A.

    2009-02-01

    This study explores the haptic rendering capabilities of a variable friction tactile interface through psychophysical experiments. In order to obtain a deeper understanding of the sensory resolution associated with the Tactile Pattern Display (TPaD), friction discrimination experiments are conducted. During the experiments, subjects are asked to explore the glass surface of the TPaD using their bare index fingers, to feel the friction on the surface, and to compare the slipperiness of two stimuli, displayed in sequential order. The fingertip position data is collected by an infrared frame and normal and translational forces applied by the finger are measured by force sensors attached to the TPaD. The recorded data is used to calculate the coefficient of friction between the fingertip and the TPaD. The experiments determine the just noticeable difference (JND) of friction coefficient for humans interacting with the TPaD.

  10. Evaluation of deep drawing force under different friction conditions

    OpenAIRE

    Lăzărescu Lucian; Banabic Dorel

    2017-01-01

    The purpose of this study is to investigate the variation of the required punch load during the deep drawing process under different friction conditions. In this regards, several deep-drawing tests of cylindrical cups were conducted under four friction conditions at the tool–blank interface. The first case was the dry deep-drawing, considered as a reference friction condition, while in the other three cases hydraulic oil, lithium-based grease and animal fat were used as lubricants. For each f...

  11. Test of measuring frictional loss of tendons for PCCVs and others

    International Nuclear Information System (INIS)

    Igaki, Tsutomu; Kondo, Shigeru; Tadano, Naonori.

    1981-01-01

    Kansai Electric Power Co., Inc., has carried out the experimental research on large capacity tendons in order to introduce the prestressing structurally required for PCCVs since 1978. This experimental research is concerned with large circular cylinder structures using the large capacity tendons of unbonded type, and aimed at clarifying the problems concerning their design and construction. Through the experiment of prestressing the partial models of full size with the tendons of 1000 t class, the basic experiment on materials, the investigations of concrete placing and tendon arrangement, and the measurement before and after prestressing were carried out, and the studies on the loss of tension the soundness of anchoring part, and the capability of construction were made. The specimens were a rectangular block with 14 tendons, a circular cylinder of two-buttress type with 3 tendons, a U-type specimen simulating the vertical section and a C-type specimen simulating the horizontal section. It seems advantageous to decrease the number of buttresses in view of workability and economy when large capacity tendons are used, and it was confirmed that two-buttress construction did not cause problem at all. It was judged that the anchoring part was sufficiently safe. Concerning the friction during tensioning, the effectiveness rate was estimated. (Kako, I.)

  12. Evaluation of Tyregrip(R) high-friction surfacing.

    Science.gov (United States)

    2012-06-01

    This report describes the installation of Tyregrip, a high friction surface, on a high accident location to reduce accident : rates. Tyregrip is a thin polymer overlay system that uses a two part epoxy binder and calcined bauxite aggregate. Postc...

  13. Evaluation of tensile strength and fracture behavior of friction welded ...

    Indian Academy of Sciences (India)

    In the present study an attempt was made to join austenitic stainless steel ... Experimental details ... This test was carried out on the friction welded samples of .... phenomenon was observed to be true if the rotational speed was increased up to ...

  14. Mechanical and topographic evaluation of esthetic brackets and its relation to frictional resistance

    Directory of Open Access Journals (Sweden)

    Vikram Pai

    2013-01-01

    Full Text Available Introduction: The purpose of this in-vitro study was to evaluate the frictional characteristics of conventional ceramic versus metal insert ceramic brackets in combination with stainless steel and Teflon-coated stainless steel archwires. Materials and Methods: Twenty brackets each, of ceramic and metal insert ceramic Maxillary canine preadjusted edgewise brackets 0.022 × 0.028 in slot and 20 archwires, each of stainless steel and Teflon-coated stainless steel (0.019 × 0.025 in were tested for frictional resistance. Friction was evaluated in a simulated Tidy′s design apparatus on universal testing machine. The kinetic friction data were analyzed using Student′s ′t′ test. The effects of surface characteristics on frictional resistance were qualitatively assessed using scanning electron microscope. Results: Metal insert ceramic brackets generated significantly lower kinetic frictional resistance than the conventional ceramic brackets with Teflon-coated stainless steel archwires (P < 0.001 as well as stainless steel archwires (P < 0.05. Conclusion: Metal insert ceramic bracket with stainless steel archwire is the best possible combination among the materials studied because it generated the least frictional resistance during simulated tooth movement.

  15. NASA evaluation of Type 2 chemical depositions. [effects of deicer deposition on aircraft tire friction performance

    Science.gov (United States)

    Yager, Thomas J.; Stubbs, Sandy M.; Howell, W. Edward; Webb, Granville L.

    1993-01-01

    Recent findings from NASA Langley tests to define effects of aircraft Type 2 chemical deicer depositions on aircraft tire friction performance are summarized. The Aircraft Landing Dynamics Facility (ALDF) is described together with the scope of the tire cornering and braking friction tests conducted up to 160 knots ground speed. Some lower speed 32 - 96 km/hr (20 - 60 mph) test run data obtained using an Instrumented Tire Test Vehicle (ITTV) to determine effects of tire bearing pressure and transverse grooving on cornering friction performance are also discussed. Recommendations are made concerning which parameters should be evaluated in future testing.

  16. EVALUATION OF A LOW FRICTION - HIGH EFFICIENCY ROLLER BEARING ENGINE

    Energy Technology Data Exchange (ETDEWEB)

    Kolarik, Robert V. II; Shattuck, Charles W.; Copper, Anthony P.

    2009-06-30

    This Low Friction (High Efficiency Roller Bearing) Engine (LFE) report presents the work done by The Timken Company to conduct a technology demonstration of the benefits of replacing hydrodynamic bearings with roller bearings in the crankshaft and camshaft assemblies of an internal combustion engine for the purpose of collecting data sufficient to prove merit. The engines in the present study have been more extensively converted to roller bearings than any previous studies (40 needle roller bearings per engine) to gain understanding of the full potential of application of bearing technology. The project plan called for comparative testing of a production vehicle which was already respected for having demonstrated low engine friction levels with a rollerized version of that engine. Testing was to include industry standard tests for friction, emissions and fuel efficiency conducted on instrumented dynamometers. Additional tests for fuel efficiency, cold start resistance and other measures of performance were to be made in the actual vehicle. Comparative measurements of noise, vibration and harshness (NVH), were planned, although any work to mitigate the suspected higher NVH level in the rollerized engine was beyond the scope of this project. Timken selected the Toyota Avalon with a 3.5L V-6 engine as the test vehicle. In an attempt to minimize cost and fabrication time, a ‘made-from’ approach was proposed in which as many parts as possible would be used or modified from production parts to create the rollerized engine. Timken commissioned its test partner, FEV Engine Technology, to do a feasibility study in which they confirmed that using such an approach was possible to meet the required dimensional restrictions and tolerances. In designing the roller bearing systems for the crank and cam trains, Timken utilized as many production engine parts as possible. The crankshafts were produced from production line forgings, which use Timken steel, modified with special

  17. A research on determining the friction losses formed in the small ...

    African Journals Online (AJOL)

    ONOS

    2010-01-18

    Jan 18, 2010 ... kler heads were used especially to irrigate landscapes areas (Rochester, 1995). ... friction in the pipe mentioned and the energy which was .... Where; Q is water flow (m3 s-1), A is cross sectional area of pipe,. (m2) and V is ...

  18. First and Second-Law Efficiency Analysis and ANN Prediction of a Diesel Cycle with Internal Irreversibility, Variable Specific Heats, Heat Loss, and Friction Considerations

    Directory of Open Access Journals (Sweden)

    M. M. Rashidi

    2014-04-01

    Full Text Available The variability of specific heats, internal irreversibility, heat and frictional losses are neglected in air-standard analysis for different internal combustion engine cycles. In this paper, the performance of an air-standard Diesel cycle with considerations of internal irreversibility described by using the compression and expansion efficiencies, variable specific heats, and losses due to heat transfer and friction is investigated by using finite-time thermodynamics. Artificial neural network (ANN is proposed for predicting the thermal efficiency and power output values versus the minimum and the maximum temperatures of the cycle and also the compression ratio. Results show that the first-law efficiency and the output power reach their maximum at a critical compression ratio for specific fixed parameters. The first-law efficiency increases as the heat leakage decreases; however the heat leakage has no direct effect on the output power. The results also show that irreversibilities have depressing effects on the performance of the cycle. Finally, a comparison between the results of the thermodynamic analysis and the ANN prediction shows a maximum difference of 0.181% and 0.194% in estimating the thermal efficiency and the output power. The obtained results in this paper can be useful for evaluating and improving the performance of practical Diesel engines.

  19. Aspects Regarding Evaluation of Friction Effects in Robotic Systems

    Directory of Open Access Journals (Sweden)

    Florina-Carmen Ciornei

    2016-06-01

    Full Text Available The paper reveals both experimentally and by numerical simulation that modelling the dynamic behaviour of a robotic system that contains pairs where spin motion exists, finally leads towards nonlinear dynamical models. Despite the fact that academic monographs upon rigid mechanics use the hypothesis that spinning torque depends linearly on the normal force, a simple experiment contradicts this assumption. To this end, the motion of an axi-symmetric body making two contacts with dry friction is analyzed. The qualitative non-linearity of spinning torque on loading force dependence is validated in the end by the modelling of the test using dynamical simulation software.

  20. Characterization of the frictional losses and heat transfer of oscillatory viscous flow through wire-mesh regenerators

    Directory of Open Access Journals (Sweden)

    A.A. Boroujerdi

    2015-12-01

    Full Text Available In this paper, new relations for calculating heat transfer and pressure drop characteristics of oscillatory flow through wire-mesh screen regenerator such as Darcy permeability, Forchheimer’s inertial coefficient, and heat transfer area per unit volume, as a function of the wire diameter are presented. According to the derived relations, thinner wires have higher pressure drop and higher heat transfer rate. The relations are applicable for all regenerative cryocoolers. Embedding the new relations into a numerical model, three Stirling-type orifice pulse tube cryocoolers with three regenerators different in length and diameter but same volume in a variety of wire diameters, have been modeled. The results achieved by the model reveal that the local heat transfer coefficient decreases with increase of the wire diameter and the length-to-diameter ratio. In addition, it was shown that the mean absolute gas–solid wire temperature difference is a linear function of wire diameter in the range investigated. The results show that for larger length-to-diameter ratios, Forchheimer’s effect will dominate frictional losses, and the variations of the frictional losses are proportional to the inverse of the wire diameter. Wire diameter has been optimized to maximize the coefficient of performance of the cryocooler. Shorter regenerators have thinner optimum wires.

  1. Evaluation of the friction force generated by monocristalyne and policristalyne ceramic brackets in sliding mechanics.

    Science.gov (United States)

    Pimentel, Roberta Ferreira; de Oliveira, Roberto Sotto Maior Fortes; Chaves, Maria das Graças Afonso Miranda; Elias, Carlos Nelson; Gravina, Marco Abdo

    2013-01-01

    To evaluate and compare "in vitro" the maximum friction force generated by three types of esthetic brackets, two types of polycrystalline conventional ceramic brackets (20/40 and InVu) and one type of sapphire monocrystalline bracket (Radiance) in dry and artificial saliva wet settings. Also, to evaluate the influence exerted by artificial saliva on the friction forces of those brackets. Tests were performed in dry and artificial saliva wet setting (Oral Balance) by using an EMIC DL 10000 testing machine, simulating a 2 mm slide of 0.019 x 0.025-in rectangular stainless steel wires over the pre-angulated and pre-torqued (right superior canine, Roth prescription, slot 0.022 x 0.030-in) brackets (n = 18 for each bracket). In order to compare groups in dry and wet settings, the ANOVA was used. For comparisons related to the dry versus wet setting, the student t test was used for each group. The results showed that in the absence of saliva the Radiance monocrystalline brackets showed the highest friction coefficients, followed by the 20/40 and the InVu polycrystalline brackets. In tests with artificial saliva, the Radiance and the 20/40 brackets had statistically similar friction coefficients and both were greater than that presented by the InVu brackets. The artificial saliva did not change the maximum friction force of the Radiance brackets, but, for the others (20/40 and InVu), an increase of friction was observed in its presence. The InVu brackets showed, in the absence and in the presence of saliva, the lowest friction coefficient.

  2. Comparative evaluation of frictional characteristics of coated low friction ligatures - Super Slick Ties™ with conventional uncoated ligatures

    Directory of Open Access Journals (Sweden)

    Deepu Leander

    2011-01-01

    Conclusions: SST produced lower levels of friction (11% for all archwire materials when compared to conventional uncoated ligatures (Dispense-A-Stix and both conventional uncoated ligatures and coated ligatures gave a rank order of coefficient of kinetic friction (μkf among archwires, with stainless steel archwires exhibiting the least and TMA TM showing the highest.

  3. Performance Evaluation on Transmission Tower-Line System with Passive Friction Dampers Subjected to Wind Excitations

    Directory of Open Access Journals (Sweden)

    Bo Chen

    2015-01-01

    Full Text Available The vibration control and performance evaluation on a transmission-tower line system by using friction dampers subjected to wind excitations are carried out in this study. The three-dimensional finite element (FE model of a transmission tower is firstly constructed. A two-dimensional lumped mass model of a transmission tower is developed for dynamic analysis. The analytical model of transmission tower-line system is proposed by taking the dynamic interaction between the tower and the transmission lines into consideration. The mechanical model of passive friction damper is presented by involving the effects of damper axial stiffness. The equation of motion of the transmission tower-line system incorporated with the friction dampers disturbed by wind excitations is established. A real transmission tower-line system is taken as an example to examine the feasibility and reliability of the proposed control approach. An extensive parameter study is carried out to find the optimal parameters of friction damper and to assess the effects of slipping force axial stiffness and hysteresis loop on control performance. The work on an example structure indicates that the application of friction dampers with optimal parameters could significantly reduce wind-induced responses of the transmission tower-line system.

  4. Experimental Evaluation of Oxide Nanoparticles as Friction and Wear Improvement Additives in Motor Oil

    Directory of Open Access Journals (Sweden)

    Nicholaos G. Demas

    2017-01-01

    Full Text Available The effect of two nanoparticle oxides on friction and wear was studied under laboratory test conditions using a reciprocating test machine and two test configurations. The addition of these nanoparticles in base stock oil under certain conditions reduced the coefficient of friction and improved wear, but that depended on the test configuration. Examination of the rubbed surfaces showed the pronounced formation of a tribofilm in some cases, while polishing on the surface was also observed in other cases. Contact configuration is important when oxide nanoparticles are being evaluated and the conclusions about their efficacy can be vastly different.

  5. Low Loss Advanced Metallic Fuel Casting Evaluation

    International Nuclear Information System (INIS)

    Kim, Kihwan; Ko, Youngmo; Kim, Jonghwan; Song, Hoon; Lee Chanbock

    2014-01-01

    The fabrication process for SFR fuel is composed of fuel slug casting, loading and fabrication of the fuel rods, and the fabrication of the final fuel assemblies. Fuel slug casting is the dominant source of fuel losses and recycles streams in the fabrication process. Recycle streams include fuel slug reworks, returned scraps, and fuel casting heels, which are a special concern in the counter gravity injection casting process because of the large masses involved. Large recycle and waste streams result in lowering the productivity and the economic efficiency of fuel production. To increase efficiency the fuel losses in the furnace chamber, crucible, and the mold, after casting a considerable amount of fuel alloy in the casting furnace, will be quantitatively evaluated. After evaluation the losses will be identified and minimized. It is expected that this study will contribute to the minimization of fuel losses and the wastes streams in the fabrication process of the fuel slugs. Also through this study the technical readiness level of the metallic fuel fabrication process will be further enhanced. In this study, U-Zr alloy system fuel slugs were fabricated by a gravity casting method. Metallic fuel slugs were successfully fabricated with 19 slugs/batch with diameter of 5mm and length of 300mm. Fuel losses was quantitatively evaluated in casting process for the fuel slugs. Fuel losses of the fuel slugs were so low, 0.1∼1.0%. Injection casting experiments have been performed to reduce the fuel loss and improve the casting method. U-Zr fuel slug having φ5.4-L250mm was soundly fabricated with 0.1% in fuel loss. The fuel losses could be minimized to 0.1%, which showed that casting technology of fuel slugs can be a feasible approach to reach the goal of the fuel losses of 0.1% or less in commercial scale

  6. Origins of Rolling Friction

    Science.gov (United States)

    Cross, Rod

    2017-01-01

    When a hard object rolls on a soft surface, or vice versa, rolling friction arises from deformation of the soft object or the soft surface. The friction force can be described in terms of an offset in the normal reaction force or in terms of energy loss arising from the deformation. The origin of the friction force itself is not entirely clear. It…

  7. Ultrasonic evaluation of friction stud welded AA 6063/AISI 1030 steel joints

    International Nuclear Information System (INIS)

    Hynes, N. Rajesh Jesudoss; Nagaraj, P.; Sujana, J. Angela Jennifa

    2014-01-01

    Highlights: • Friction stud welding of AA 6063 and AISI 1030 was done successfully. • Ultrasonic evaluation of interfacial properties. • EDX analysis confirms intermetallic compound (FeAl) in the interfacial region. - Abstract: Friction stud welding is a promising technique in many applications related to oil and gas industries. It is used to attach grating to offshore oil platforms in areas where arc welding is not permitted because of the risk of causing a fire or explosion. Attachment of anodes inside seawater discharge pipelines in a gas processing plant is performed by this process. This solid state joining process permits metal combinations such as welding of aluminum studs to steel which would be problematic with arc welding because of the formation of thick and brittle inter-metallic compounds. In the present work, AA 6063 is joined to AISI 1030 steel using friction stud welding machine. Properties that are of interest to manufacturing applications such as Young’s modulus, longitudinal velocity, bulk modulus and shear modulus are evaluated by means of an ultrasonic flaw detector. At the interface of the joint, there is an increase of 4.4%, 1.8%, 1.15% and 4.42% is observed for the properties Young’s modulus, longitudinal velocity, bulk modulus and shear modulus respectively. This is due to the formation of intermetallic compound and increase in hardness at the interfacial region. Energy Dispersive X-ray analysis confirms the presence of FeAl as the intermetallic compound. Scanning Electron Microscope evaluation shows the presence of an unbound zone at the center of the inner region which is due to the minimum rotational speed and low axial load experienced at that point. In the unbound zone, there is an incomplete bond between dissimilar metals and it is detrimental to joint strength. Optimum value of friction time and usage of pure aluminum interlayer during the friction stud welding process hinders the formation of unbound zone and enhances the

  8. Clinical and cost effectiveness evaluation of low friction and shear garments.

    Science.gov (United States)

    Smith, G; Ingram, A

    2010-12-01

    To determine the effectiveness of Parafricta low-friction garments in reducing the incidence and prevalence of pressure ulceration and to evaluate the curative aspects of these products on pre-existing skin breakdown within a hospital setting. Patients with a Waterlow score of >15 and who were unable to reposition independently were offered the low-friction undergarments and bootees. A total of 650 patient cases were initially reviewed. Of these, 204 met the criteria for use of the products in the 3 months prior to the start of the evaluation (cohort 1) and 165 patients met the criteria during the period when the garments were used (cohort 2). Data collected included pressure ulcer incidence, location, grading, and outcome of ulcer on discharge. Locally derived costs for length of stay, wound dressings, pressure-redistributing mattresses and additional cost of the low-friction garments were applied to build a cost-effectiveness model. In patients at risk of skin breakdown there was a statistically significant reduction in the number of patients who developed pressure ulcers following use of the low-friction garments in cohort 2 when compared with cohort 1 (16% reduction; p = 0.0286). In addition, the number of patients who were ulcer free on admission but who developed ulcers and then improved or completely healed before discharge was also statistically significant (41% increase; p = 0.0065) when cohort 2 was compared with cohort 1. Fewer patients admitted with ulcers deteriorated when using the low-friction garments (21% reduction; p = 0.0012). The costs, which were calculated by comparing patient throughput for these patients, suggest that the savings associated with preventing skin breakdown outweighed the cost of the products used (base case model indicated a saving of over £63,000 per 100 at risk patients). The results support the conclusion that low-friction garment products have a role to play in the prevention of skin breakdown, and appear to be both

  9. Computational simulations of frictional losses in pipe networks confirmed in experimental apparatusses designed by honors students

    Science.gov (United States)

    Pohlman, Nicholas A.; Hynes, Eric; Kutz, April

    2015-11-01

    Lectures in introductory fluid mechanics at NIU are a combination of students with standard enrollment and students seeking honors credit for an enriching experience. Most honors students dread the additional homework problems or an extra paper assigned by the instructor. During the past three years, honors students of my class have instead collaborated to design wet-lab experiments for their peers to predict variable volume flow rates of open reservoirs driven by gravity. Rather than learn extra, the honors students learn the Bernoulli head-loss equation earlier to design appropriate systems for an experimental wet lab. Prior designs incorporated minor loss features such as sudden contraction or multiple unions and valves. The honors students from Spring 2015 expanded the repertoire of available options by developing large scale set-ups with multiple pipe networks that could be combined together to test the flexibility of the student team's computational programs. The engagement of bridging the theory with practice was appreciated by all of the students such that multiple teams were able to predict performance within 4% accuracy. The challenges, schedules, and cost estimates of incorporating the experimental lab into an introductory fluid mechanics course will be reported.

  10. CFD modelling of the wall friction velocity field in the ITER tokamak resulting from airflow during a loss of vacuum accident—Consequences for particle resuspension

    Energy Technology Data Exchange (ETDEWEB)

    Gélain, T., E-mail: thomas.gelain@irsn.fr; Rondeau, A.; Peillon, S.; Sabroux, J.C.; Gensdarmes, F.

    2015-11-15

    During a loss of vacuum accident (LOVA), dusts that will be present in the future tokamak ITER are likely to be re-suspended. Such aerosols formed may present a risk for explosion and airborne contamination. This article presents parameters that govern the forces affecting particles deposited on a wall and subject to airflow. It is shown the influence of three parameters in the dust mobilization mechanism, i.e.: the particles diameter, the fluid density and the friction velocity. From numerical simulations, it is determined the evolution of wall friction velocities in the vacuum vessel (VV) of ITER during a LOVA. The numerical calculations performed with ANSYS CFX code provide average friction velocities in the lower part of the tokamak between 12 m s{sup −1} at a pressure of 150 Pa, and 0.5 m s{sup −1} at a pressure of 10{sup 5} Pa.

  11. Micro-/nanoscaled irreversible Otto engine cycle with friction loss and boundary effects and its performance characteristics

    International Nuclear Information System (INIS)

    Nie, Wenjie; Liao, Qinghong; Zhang, ChunQiang; He, Jizhou

    2010-01-01

    An irreversible cycle model of the micro-/nanoscaled Otto engine cycle with internal friction loss is established. The general expressions of the work output and efficiency of the cycle are calculated based on the finite system thermodynamic theory, in which the quantum boundary effect of gas particles as working substance and the mechanical Casimir effect of gas system are considered. It is found that, for a micro-/nanoscaled Otto cycle devices, the work output W and efficiency η of the cycle can be expressed as the functions of the temperature ratio τ of the two heat reservoirs, the volume ratio r V and the surface area ratio r A of the two isochoric processes, the dimensionless thermal wavelength λ and other parameters of cycle, while for a macroscaled Otto cycle devices, the work output W 0 and efficiency η 0 of the cycle are independent of the surface area ratio r A and the dimensionless thermal wavelength λ. Further, the influence of boundary of cycle on the performance characteristics of the micro-/nanoscaled Otto cycle are analyzed in detail by introducing the output ratio W/W 0 and efficiency ratio η/η 0 . The results present the general performance characteristics of a micro-/nanoscaled Otto cycle and may serve as the basis for the design of a realistic Otto cycle device in micro-/nanoscale.

  12. Comparison of numerical and experimental results on flow rate and friction losses in water outflow from extended pipelines

    International Nuclear Information System (INIS)

    Makukhin, A.A.; Fisenko, V.V.; Kolykhanov, V.N.

    1985-01-01

    Results are presented of numerical calculation and experimental determinaion of the flow rate and friction losses during boiling-up water flow motion in extended pipelines at critical outflow regime with account of compressibility of heat-transferring medium. The difference of the calculation model proposed is in the fact that the presence of a finite length pipeline portion is implied where the Mach number (M) remains equal to 1 at a continuously varying flow rate and the sound velocity varying from its thermodynamical equilibrium value inside the channel to the non-equilibrium one at the exit. At that the deceleration pressure along this portion remains constant, and the M=1 condition is maintained automatically due to a constant flow rate. Analysis of numerical experiment has shown that the new scheme of heat transfer by critical two-phase flow is more efficient than that by one-phase flow within the 0.5 to 8 MPa range of initial pressures at a 0-50 K subcooling as a result of a decrease in the head of transfering pumps and a reduction in the pipeline pressure. Experiments carried out show good agreement with the calclation data

  13. Non-Newtonian fluids: Frictional pressure loss prediction for fully-developed flow in straight pipes

    Science.gov (United States)

    1991-10-01

    ESDU 91025 discusses models used to describe the rheology of time independent pseudohomogeneous non-Newtonian fluids (power-law, Bingham, Herschel-Bulkley and a generalized model due to Metzner and Reed); they are used to calculate the laminar flow pressure drop (which is independent of pipe roughness in this regime). Values of a generalized Reynolds number are suggested to define transitional and turbulent flow. For turbulent flow in smooth pipes, pressure loss is estimated on the basis of an experimentally determined rheogram using either the Dodge-Metzner or Bowen approach depending on the available measurements. Bowen requires results for at least two pipe diameters. The choice of Dodge-Metzner when data are limited is discussed; seven possible methods are assessed against five sets of experimental results drawn from the literature. No method is given for transitional flow, which it is suggested should be avoided, but the turbulent correlation is recommended because it will yield an overestimate. Suggestions are made for the treatment of roughness effects. Several worked examples illustrate the use of the methods and a flowchart guides the user through the process from experimentally characterizing the behavior of the fluid to determining the pressure drop. A computer program, ESDUpac A9125, is also provided.

  14. Evaluation of Static Friction of Polycrystalline Ceramic Brackets after Conditioning with Different Powers of Er:YAG Laser.

    Science.gov (United States)

    Arash, Valiollah; Javanmard, Saeed; Eftekhari, Zeinab; Rahmati-Kamel, Manouchehr; Bahadoram, Mohammad

    2015-01-01

    This research aimed to reduce the friction between the wire and brackets by Er:YAG laser. To measure the friction between the wires and brackets in 0° and 10° of wire angulations, 40 polycrystalline ceramic brackets (Hubit, South Korea) were divided into 8 study groups and irradiated by 100, 200, and 300 mj/s of Er:YAG laser power. Two groups of brackets were not irradiated. The friction between the wires and brackets was measured with universal testing machine (SANTAM) with a segment of .019 × .025 SS wire pulled out of the slot of bracket. ANOVA and t-test were used for analyzing the results. To evaluate the effect of the laser on surface morphology of the bracket, SEM evaluations were carried out. The mean frictional resistances between the brackets and wires with 0° of angulation by increasing the laser power decreased compared with control group, but, in 10° of angulation, the friction increased regardless of the laser power and was comparable to the friction of nonirradiated brackets. Furthermore, with each laser power, frictional resistance of brackets in 10° of angulation was significantly higher than 0° of angulation. These results were explained by SEM images too.

  15. Impact Damage Evaluation Method of Friction Disc Based on High-Speed Photography and Tooth-Root Stress Coupling

    International Nuclear Information System (INIS)

    Yin, L; Shao, Y M; Liu, J; Zheng, H L

    2015-01-01

    The stability of friction disc could be seriously affected by the tooth surface damage due to poor working conditions of the wet multi-disc brake in heavy trucks. There are few current works focused on the damage of the friction disc caused by torsion-vibration impacts. Hence, it is necessary to investigate its damage mechanisms and evaluation methods. In this paper, a damage mechanism description and evaluation method of a friction disc based on the high-speed photography and tooth-root stress coupling is proposed. According to the HighSpeed Photography, the collision process between the friction disc and hub is recorded, which can be used to determine the contact position and deformation. Combined with the strain-stress data obtained by the strain gauge at the place of the tooth-root, the impact force and property are studied. In order to obtain the evaluation method, the damage surface morphology data of the friction disc extracted by 3D Super Depth Digital Microscope (VH-Z100R) is compared with the impact force and property. The quantitative relationships between the amount of deformation and collision number are obtained using a fitting analysis method. The experimental results show that the damage of the friction disc can be evaluated by the proposed impact damage evaluation method based on the high-speed photography and tooth-root stress coupling. (paper)

  16. Evaluation of the friction force generated by monocristalyne and policristalyne ceramic brackets in sliding mechanics

    Directory of Open Access Journals (Sweden)

    Roberta Ferreira Pimentel

    2013-02-01

    Full Text Available OBJECTIVE: To evaluate and compare "in vitro" the maximum friction force generated by three types of esthetic brackets, two types of polycrystalline conventional ceramic brackets (20/40 and InVu and one type of sapphire monocrystalline bracket (Radiance in dry and artificial saliva wet settings. Also, to evaluate the influence exerted by artificial saliva on the friction forces of those brackets. METHODS: Tests were performed in dry and artificial saliva wet setting (Oral Balance by using an EMIC DL 10000 testing machine, simulating a 2 mm slide of 0.019 x 0.025-in rectangular stainless steel wires over the pre-angulated and pre-torqued (right superior canine, Roth prescription, slot 0.022 x 0.030-in brackets (n = 18 for each bracket. In order to compare groups in dry and wet settings, the ANOVA was used. For comparisons related to the dry versus wet setting, the student t test was used for each group. RESULTS: The results showed that in the absence of saliva the Radiance monocrystalline brackets showed the highest friction coefficients, followed by the 20/40 and the InVu polycrystalline brackets. In tests with artificial saliva, the Radiance and the 20/40 brackets had statistically similar friction coefficients and both were greater than that presented by the InVu brackets. The artificial saliva did not change the maximum friction force of the Radiance brackets, but, for the others (20/40 and InVu, an increase of friction was observed in its presence. CONCLUSION: The InVu brackets showed, in the absence and in the presence of saliva, the lowest friction coefficient.OBJETIVO: avaliar e comparar in vitro as cargas máximas de atrito geradas por três tipos de braquetes estéticos, sendo dois deles cerâmicos policristalinos convencionais (20/40 e InVu e um monocristalino de safira (Radiance, em ambientes seco e umedecido por saliva artificial. Também avaliar a influência exercida pela saliva artificial sobre as cargas de atrito dos referidos

  17. Force Rendering and its Evaluation of a Friction-Based Walking Sensation Display for a Seated User.

    Science.gov (United States)

    Kato, Ginga; Kuroda, Yoshihiro; Kiyokawa, Kiyoshi; Takemura, Haruo

    2018-04-01

    Most existing locomotion devices that represent the sensation of walking target a user who is actually performing a walking motion. Here, we attempted to represent the walking sensation, especially a kinesthetic sensation and advancing feeling (the sense of moving forward) while the user remains seated. To represent the walking sensation using a relatively simple device, we focused on the force rendering and its evaluation of the longitudinal friction force applied on the sole during walking. Based on the measurement of the friction force applied on the sole during actual walking, we developed a novel friction force display that can present the friction force without the influence of body weight. Using performance evaluation testing, we found that the proposed method can stably and rapidly display friction force. Also, we developed a virtual reality (VR) walk-through system that is able to present the friction force through the proposed device according to the avatar's walking motion in a virtual world. By evaluating the realism, we found that the proposed device can represent a more realistic advancing feeling than vibration feedback.

  18. Nondestructive Evaluation of Friction Stir-Welded Aluminum Alloy to Coated Steel Sheet Lap Joint

    Science.gov (United States)

    Das, H.; Kumar, A.; Rajkumar, K. V.; Saravanan, T.; Jayakumar, T.; Pal, Tapan Kumar

    2015-11-01

    Dissimilar lap joints of aluminum sheet (AA 6061) of 2 mm thickness and zinc-coated steel sheet of 1 mm thickness were produced by friction stir welding with different combinations of rotational speed and travel speed. Ultrasonic C- and B-scanning, and radiography have been used in a complementary manner for detection of volumetric (cavity and flash) and planar (de bond) defects as the defects are in micron level. Advanced ultrasonic C-scanning did not provide any idea about the defects, whereas B-scanning cross-sectional image showed an exclusive overview of the micron-level defects. A digital x-ray radiography methodology is proposed for quality assessment of the dissimilar welds which provide three-fold increase in signal-to-noise ratio with improved defect detection sensitivity. The present study clearly shows that the weld tool rotational speed and travel speed have a decisive role on the quality of the joints obtained by the friction stir welding process. The suitability of the proposed NDE techniques to evaluate the joint integrity of dissimilar FSW joints is thus established.

  19. Evaluation of interfacial bonding in dissimilar materials of YSZ-alumina composites to 6061 aluminium alloy using friction welding

    International Nuclear Information System (INIS)

    Uday, M.B.; Ahmad Fauzi, M.N.; Zuhailawati, H.; Ismail, A.B.

    2011-01-01

    Research highlights: → Friction-welding process. → Joining between ceramic composite and metal alloy. → Slip casting of the yttria stabilized zirconia/alumina composite samples. - Abstract: The interfacial microstructures characteristics of alumina ceramic body reinforced with yttria stabilized zirconia (YSZ) was evaluated after friction welding to 6061 aluminum alloy using optical and electron microscopy. Alumina rods containing 25 and 50 wt% yttria stabilized zirconia were fabricated by slip casting in plaster of Paris (POP) molds and subsequently sintered at 1600 deg. C. On the other hand, aluminum rods were machine down to the required dimension using a lathe machine. The diameter of the ceramic and the metal rods was 16 mm. Rotational speeds for the friction welding were varied between 900 and 1800 rpm. The friction pressure was maintained at 7 MPa for a friction time of 30 s. Optical and scanning electron microscopy was used to analyze the microstructure of the resultant joints, particularly at the interface. The joints were also examined with EDX line (energy dispersive X-ray) in order to determine the phases formed during the welding. The mechanical properties of the friction welded YSZ-Al 2 O 3 composite to 6061 alloy were determined with a four-point bend test and Vickers microhardness. The experimental results showed the degree of deformation varied significantly for the 6061 Al alloy than the ceramic composite part. The mechanical strength of friction-welded ceramic composite/6061 Al alloy components were obviously affected by joining rotational speed selected which decreases in strength with increasing rotational speed.

  20. Nondestructive Evaluation of the Friction Weld Process on 2195/2219 Grade Aluminum

    Science.gov (United States)

    Suits, Michael W.; Clark, Linda S.; Cox, Dwight E.

    1999-01-01

    In 1996, NASA's Marshall Space Flight Center began an ambitious program designed to find alternative methods of repairing conventional TIG (Tungsten Inert Gas) welds and VPPA (Variable Polarity Plasma Arc) welds on the Space Shuttle External Tank without producing additional heat-related anomalies or conditions. Therefore, a relatively new method, invented by The Welding Institute (TWI) in Cambridge, England, called Friction Stir Welding (FSW), was investigated for use in this application, as well as being used potentially as an initial weld process. As with the conventional repair welding processes, nondestructive evaluation (NDE) plays a crucial role in the verification of these repairs. Since it was feared that conventional NDE might have trouble with this type of weld structure (due to shape of nugget, grain structure, etc.) it was imperative that a complete study be performed to address the adequacy of the NDE process. This paper summarizes that process.

  1. Fatigue strength evaluation of friction stir welded aluminium joints using the nominal and notch stress concepts

    International Nuclear Information System (INIS)

    Barsoum, Z.; Khurshid, M.; Barsoum, I.

    2012-01-01

    Highlights: ► Fatigue testing and evaluation of friction stir welded butt and overlap joints. ► Evaluation based on nominal and effective notch stress concept. ► Comparison with different design recommendations and codes. ► Higher fatigue strength and SN-slopes is observed. ► New fatigue design recommendations proposed for FSW joints. -- Abstract: In this study the fatigue strength is investigated for Friction Stir Welded (FSW) overlap and butt welded joints in different thicknesses based on nominal and effective notch stress concepts. The fatigue test results are compared with fatigue strength recommendations according to EN 1999-1-3 and International Institute of Welding (IIW). The results are also compared with available published data and Finite Element Analysis (FEA) is carried out to investigate the effect of plate thickness and nugget size on the fatigue strength of overlap joints. 3–3 mm butt welded joints shows the highest fatigue strength in comparison with 3–5 mm butt welded and overlap joints. Slopes of the SN-curves for two different joint types differ from the slope recommended by IIW. A specific failure trend is observed in overlap FSW joints. However, the slopes of the SN-curves are in close agreement with slopes found in EN 1999-1-3. The slopes of various published results and test results presented in this study are in good agreement with each other. The suggested fatigue design curves for the nominal and effective notch stress concept have a higher slope than given for fusion welds by IIW.

  2. Comparison of the Friction-Loss Coefficient for the Gap of Two Contact Surfaces and a Crack

    International Nuclear Information System (INIS)

    Nam, Ho Yun; Choi, Byoung Hae; Kim, Jong Bum; Lee, Young Bum

    2011-01-01

    A leak-detection method has been developed by measuring the pressure variation between the inner and outer heat transfer tubes of a double-wall tube steam generator. An experiment was carried out to measure the leak rate in the gap between two surfaces pressed with a hydraulic press in order to simulate the phenomena, and a correlation was determined for the leak rate in a micro gap. However, in the correlation, the gap width and friction coefficient were coupled with the surface roughness, which affects the two parameters. The two parameters were separated using a surface-contact model to develop a correlation for the friction coefficient. The correlation was compared with the existing correlations used for crack analysis. Although the applied ranges of Reynolds numbers were different, the developed correlation for Reynolds numbers of 0.1.0.35 showed similar tendencies to existing correlations used for higher Reynolds numbers

  3. Evaluation of two transport aircraft and several ground test vehicle friction measurements obtained for various runway surface types and conditions. A summary of test results from joint FAA/NASA Runway Friction Program

    Science.gov (United States)

    Yager, Thomas J.; Vogler, William A.; Baldasare, Paul

    1990-01-01

    Tests with specially instrumented NASA Boeing 737 and 727 aircraft together with several different ground friction measuring devices were conducted for a variety of runway surface types and conditions. These tests are part of joint FAA/NASA Aircraft/Ground Vehicle Runway Friction Program aimed at obtaining a better understanding of aircraft ground handling performance under adverse weather conditions and defining relationships between aircraft and ground vehicle tire friction measurements. Aircraft braking performance on dry, wet, snow and ice-covered runway conditions is discussed as well as ground vehicle friction data obtained under similar runway conditions. For a given contaminated runway surface condition, the correlation between ground vehicles and aircraft friction data is identified. The influence of major test parameters on friction measurements such as speed, test tire characteristics, type and amount of surface contaminant, and ambient temperature are discussed. The effect of surface type on wet friction levels is also evaluated from comparative data collected on grooved and ungrooved concrete and asphalt surfaces.

  4. Experimental evaluation of mechanical heart support system based on viscous friction disc pump

    Directory of Open Access Journals (Sweden)

    A. M. Chernyavskiy

    2017-01-01

    Full Text Available Aim. Experimental evaluation of the viscous friction disk pump efficiency, studying the relationship between inter-disk clearance and sizes of input and output ports and pump performance parameters.Materials and methods. To assess the characteristics and to optimize the disk friction pump design the pump model and experimental stand were created. Pump dimensions were set on the basis of medical and biological requirements for mechanical heart support systems and with due consideration of the experimental studies of our colleagues from Pennsylvania. Flow volume of the working fluid was measured by float rotameter Krohne VA-40 with measurement error of not more than 1%. The pressure values in the hydrodynamic circuit were measured using a monitor manufactured by Biosoft-M. Expansion device allowed changing the flow resistance of the system simulating the total peripheral resistance of the circulatory system.Results. Linear direct correlation between the pump performance and the pressure drop of liquid being created at the inlet and outlet of the pump was obtained. The required flow rate (5–7 l/min and pressure (90–100 mmHg were reached when the rotor speed was in the range of 2500–3000 rev/min. It has been shown that the increase of the inlet diameter to 15 mm has not resulted in a significant increase in the pump performance, and that the highest efficiency values can be obtained for the magnitude of inter-disk gap of 0.4–0.5 mm.Conclusion. Designed and manufactured experimental disc pump model for pumping fluid has showed the fundamental possibility to use this model as a system for mechanical support of the heart.

  5. Evaluation of frictional resistance between monocrystalline (ICE brakcets and Stainless Steel, Beta TMA and NiTiarch wires

    Directory of Open Access Journals (Sweden)

    Meysam Mirzaie

    2013-09-01

    Full Text Available Introduction: When using sliding mechanics for space closure during orthodontic treatment, friction occurs at the bracket-wire interface. The aim of this study was to evaluate the frictional resistance between monocrystalline (ICE brackets and Stainless Steel, Beta TMA and NiTi wires. Methods: In this experimental study, we used 5 different types of orthodontic wires. Brackets and wires were divided in to 5 groups: 1-(monocrystalline+stainless steel 18 2–(monocrystalline+stainless steel 19×25 3-(monocrystalline+Beta-TMA 4–(monocrystalline+Beta TMA 19×25 5-(monocrystalline+NiTi 18. Instron Universal Testing Machine was used to investigate the static frictional resistance. The angulation between bracket and wire was 0 and the wires were pulled through the slots at a speed of 10 mm/min. Tests were performed 10 times for each group in artificial saliva. The average of 10 forces recorded was considered as static friction. One-way ANOVA and SPSS Version 18 and LSD post hoc test were used to evaluate the results of the study. Results: The mean static frictional force for each group was: group1: 0.82 ± 0.14, group 2: 1.09 ± 0.30, group 3: 0.87 ± 0.53, group 4: 1.9 ± 1.16, group 5: 1.42 ± 0.30. There was a significant difference when comparing the two groups of similar wires in terms of shape (round or rectangular cross-section as when comparing Beta TMA 18 and 19×25 arch wires with each other, the obtained p-value was 0.023, while the obtained p-value for the comparison of stainles steel arch wires was 0.034 . Conclusions: The result of this study shows that Stainless Steel 18 wires generate the least amount of friction and round wires produce less friction than the rectangular wires. Beta TMA wires generate the highest amount of friction.

  6. Evaluation of frictional resistance between monocrystalline (ICE brakcets and Stainless Steel, Beta TMA and NiTi arch wires

    Directory of Open Access Journals (Sweden)

    Meysam Mirzaie

    2013-09-01

    Full Text Available Introduction: When using sliding mechanics for space closure during orthodontic treatment, friction occurs at the bracket-wire interface. The aim of this study was to evaluate the frictional resistance between monocrystalline (ICE brackets and Stainless Steel, Beta TMA and NiTi wires. Methods: In this experimental study, we used 5 different types of orthodontic wires. Brackets and wires were divided in to 5 groups: 1-(monocrystalline+stainless steel 18 2–(monocrystalline+stainless steel 19×25 3-(monocrystalline+Beta-TMA 4–(monocrystalline+Beta TMA 19×25 5-(monocrystalline+NiTi 18. Instron Universal Testing Machine was used to investigate the static frictional resistance. The angulation between bracket and wire was 0 and the wires were pulled through the slots at a speed of 10 mm/min. Tests were performed 10 times for each group in artificial saliva. The average of 10 forces recorded was considered as static friction. One-way ANOVA and SPSS Version 18 and LSD post hoc test were used to evaluate the results of the study. Results: The mean static frictional force for each group was: group1: 0.82±0.14, group 2: 1.09±0.30, group 3: 0.87±0.53, group 4: 1.9±1.16, group 5: 1.42±0.30. There was a significant difference when comparing the two groups of similar wires in terms of shape (round or rectangular cross-section as when comparing Beta TMA 18 and 19×25 arch wires with each other, the obtained p-value was 0.023, while the obtained p-value for the comparison of stainles steel arch wires was 0.034. Conclusions: The result of this study shows that Stainless Steel 18 wires generate the least amount of friction and round wires produce less friction than the rectangular wires. Beta TMA wires generate the highest amount of friction.

  7. An Evaluation of the FLAG Friction Model frictmultiscale2 using the Experiments of Juanicotena and Szarynski

    Energy Technology Data Exchange (ETDEWEB)

    Zocher, Marvin Anthony [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hammerberg, James Edward [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-11-15

    The experiments of Juanicotena and Szarynski, namely T101, T102, and T105 are modeled for purposes of gaining a better understanding of the FLAG friction model frictmultiscale2. This exercise has been conducted as a first step toward model validation. It is shown that with inclusion of the friction model in the numerical analysis, the results of Juanicotena and Szarynski are predicted reasonably well. Without the friction model, simulation results do not match the experimental data nearly as well. Suggestions for follow-on work are included.

  8. Evaluation of friction produced by self-ligating, conventional and Barbosa Versatile brackets

    Directory of Open Access Journals (Sweden)

    Jurandir Antonio BARBOSA

    Full Text Available Abstract Introduction The Barbosa Versatile bracket design may provide lower frictional force and greater sliding. However, no in vitro studies have shown its sliding mechanisms and frictional resistance, particularly in comparison with other self-ligating or conventional brackets. Objective To compare the frictional resistance among self-ligating brackets (EasyClip/ Aditek, Damon MX/ Ormco and In Ovation R/ GAC; conventional brackets (Balance Roth/ GAC, and Roth Monobloc/ Morelli; and Barbosa Versatile bracket (Barbosa Versatile/ GAC with different angles and arch wires. Material and method Brackets were tested with the 0.014", 0.018", 0.019"×0.025" and 0.021"×0.025" stainless steel wires, with 0, 5, 10, 15 and 20 degree angulations. Tying was performed with elastomeric ligature for conventional and Barbosa Versatile brackets, or with a built-in clip system of the self-ligating brackets. A universal testing machine was used to obtain sliding strength and friction value readouts between brackets and wires. Result Three-way factorial ANOVA 4×5×6 (brackets × angulation × wire and Tukey tests showed statistically significant differences for all factors and all interactions (p<0.0001. Static frictional resistance showed a lower rate for Barbosa Versatile bracket and higher rates for Roth Monobloc and Balance brackets. Conclusion The lowest frictional resistance was obtained with the Barbosa Versatile bracket and self-ligating brackets in comparison with the conventional type. Increasing the diameter of the wires increased the frictional resistance. Smaller angles produced less frictional resistance.

  9. Fretting friction and wear characteristics of magnetorheological fluid under different magnetic field strengths

    International Nuclear Information System (INIS)

    Zhang, P.; Lee, K.H.; Lee, C.H.

    2017-01-01

    A magnetorheological fluid (MRF) performs differently under different magnetic field strength. This study examined the fretting friction and wear characteristics of MRFs under a range of magnetic field strengths and oscillation frequencies. The fretting friction and wear behaviors of MRF are investigated using a fretting friction and wear tester. The surfaces of specimen are examined by optical microscopy and 3D surface profilometer before and after the tests and wear surface profiles, the wear volume loss and wear coefficient for each magnetic field strength are evaluated. The results show that the friction and wear properties of MRF change according to the magnetic field strength and oscillation frequency. - Highlights: • Fretting friction and wear characteristics of MRF is examined. • The friction coefficients increased with increasing magnetic field strength. • The coefficient of friction decreased with increasing oscillation frequency. • Wear volume and coefficient become worse with increasing magnetic field strength.

  10. Evaluation of friction in orthodontics using various brackets and archwire combinations-an in vitro study.

    Science.gov (United States)

    Kumar, Sujeet; Singh, Shamsher; Hamsa P R, Rani; Ahmed, Sameer; Prasanthma; Bhatnagar, Apoorva; Sidhu, Manreet; Shetty, Pramod

    2014-05-01

    The aim of this study was to compare frictional resistance which was produced between conventional brackets (0.022 slot Otho-Organiser) and self ligating brackets (active Forestadent and passive Damon III) by using various arch wire combinations (0.016 Niti, 0.018 Niti, 0.017 x 0.025 SS and 0.019 x 0.025 SS). An experimental model which consisted of 5 aligned stainless steel 0.022-in brackets was used to assess frictional forces which were produced by SLBs (self ligating brackets) and CELs (conventional elastomeric ligatures) with use of 0.016 nickel titanium, 0.018 nickel titanium, 0.017 X 0.025"stainless steel and 0.019 X 0.025"stainless steel wires. One way ANOVA test was used to study the effect of the bracket type, wire alloy and section on frictional resistance test . Conventional brackets produced highest levels of friction for all bracket/archwire combinations. Both Damon III and Forestadent brackets were found to produce significantly lower levels of friction when they were compared with elastomerically tied conventional brackets. SLBs are valid alternatives for low friction during sliding mechanics.

  11. Evaluation of the Friction of Self-Ligating and Conventional Bracket Systems

    Science.gov (United States)

    Tecco, Simona; Di Iorio, Donato; Nucera, Riccardo; Di Bisceglie, Beatrice; Cordasco, Giancarlo; Festa, Felice

    2011-01-01

    Objectives: This in vitro study evaluated the friction (F) generated by aligned stainless steel (SS) conventional brackets, self-ligating Damon MX© brackets (SDS Ormco, Glendora, California, USA), Time3© brackets (American Orthodontics, Sheboygan, Wisconsin, USA), Vision LP© brackets (American Orthodontics), and low-friction Slide© ligatures (Leone, Firenze, Italy) coupled with various SS, nickel-titanium (NiTi), and beta-titanium (TMA) archwires. Methods: All brackets had a 0.022-inch slot, and the orthodontic archwires were 0.014-inch, 0.016-inch, 0.014×0.025-inch, 0.018×0.025-inch, and 0.019×0.025-inch NiTi; 0.017×0.025-inch TMA; and 0.019×0.025-inch SS. Each bracket-archwire combination was tested 10 times. In the test, 10 brackets of the same group were mounted in alignment on a metal bar. The archwires moved through all the 10 brackets at a crosshead speed of 0.5 mm/min (each run lasted approximately 5 min). The differences among 5 groups of brackets were analyzed through the Kruskal-Wallis test, and a Mann-Whitney test was calculated as post hoc analysis. The P value was set at 0.05. Results: Coupled with 0.014-inch NiTi and 0.016-inch NiTi, Victory Series© brackets generated the greatest F, while Damon MX© and Vision LP© brackets generated the lowest (Pbrackets and Slide© ligatures. Coupled with all the rectangular archwires, Victory Series© brackets, Slide© ligatures, and Vision LP© self-ligating brackets generated significantly lower F than did Time3© and Damon MX© self-ligating brackets (Pbrackets are a family of brackets that, in vitro, can generate different levels of F when coupled with thin or thick, rectangular, or round archwires. Clinical conclusions based on our results are not possible due to the limitations of the experimental conditions. PMID:21769273

  12. Evaluation of prestress losses in nuclear reactor containments

    International Nuclear Information System (INIS)

    Lundqvist, Peter; Nilsson, Lars-Olof

    2011-01-01

    Research highlights: → Prestress losses in reactor containments were estimated using prediction models. → The predicted prestress losses were compared to long-term measurements. → The accuracy of the models was improved by considering actual drying conditions. → Predictions by CEB/FIP MC 1999 and ACI 209 were closest to the measured losses. - Abstract: The most critical safety barrier in a nuclear power plant, the concrete containment, is prestressed by hundreds of tendons, both horizontally and vertically. The main purpose of the containment is to prevent radioactive discharge to the environment in the case of a serious internal accident. Due to creep and shrinkage of concrete and relaxation of the prestressing steel, tendon forces decrease with time. These forces are thus measured in Swedish containments with unbonded tendons at regular in-service inspections. In this paper, the prestress losses obtained from these in-service inspections are compared to losses estimated using several prediction models for creep, shrinkage and relaxation. In an attempt to increase the accuracy of these models, existing expressions for the development of shrinkage were modified using previous findings on the humidity and temperature inside two Swedish containments. The models which were used and modified for predicting creep and shrinkage were CEB-FIP Model Codes 1990 and 1999, ACI 209, Model B3 and GL2000. Eurocode 2 was used for the prediction of relaxation. The results show that the most accurate of the models were CEB/FIP MC 99 and ACI 209. Depending on the model, the accuracy of the prediction models was increased by 0.5-1.2 percentage points of prestress losses when using the modified development of shrinkage. Furthermore, it was found that the differences between the different models depend mainly on the prediction of creep. Possible explanations for the deviation between the calculated and measured models can be the influence of reinforcement on creep and shrinkage

  13. Evaluation of prestress losses in nuclear reactor containments

    Energy Technology Data Exchange (ETDEWEB)

    Lundqvist, Peter, E-mail: peter.lundqvist@kstr.lth.s [Div. of Structural Engineering, Lund University, Lund (Sweden); Nilsson, Lars-Olof [Div. of Building Materials, Lund University, Lund (Sweden)

    2011-01-15

    Research highlights: Prestress losses in reactor containments were estimated using prediction models. The predicted prestress losses were compared to long-term measurements. The accuracy of the models was improved by considering actual drying conditions. Predictions by CEB/FIP MC 1999 and ACI 209 were closest to the measured losses. - Abstract: The most critical safety barrier in a nuclear power plant, the concrete containment, is prestressed by hundreds of tendons, both horizontally and vertically. The main purpose of the containment is to prevent radioactive discharge to the environment in the case of a serious internal accident. Due to creep and shrinkage of concrete and relaxation of the prestressing steel, tendon forces decrease with time. These forces are thus measured in Swedish containments with unbonded tendons at regular in-service inspections. In this paper, the prestress losses obtained from these in-service inspections are compared to losses estimated using several prediction models for creep, shrinkage and relaxation. In an attempt to increase the accuracy of these models, existing expressions for the development of shrinkage were modified using previous findings on the humidity and temperature inside two Swedish containments. The models which were used and modified for predicting creep and shrinkage were CEB-FIP Model Codes 1990 and 1999, ACI 209, Model B3 and GL2000. Eurocode 2 was used for the prediction of relaxation. The results show that the most accurate of the models were CEB/FIP MC 99 and ACI 209. Depending on the model, the accuracy of the prediction models was increased by 0.5-1.2 percentage points of prestress losses when using the modified development of shrinkage. Furthermore, it was found that the differences between the different models depend mainly on the prediction of creep. Possible explanations for the deviation between the calculated and measured models can be the influence of reinforcement on creep and shrinkage of concrete and

  14. Basic data generation and pressure loss coefficient evaluation for HANARO core thermal-hydraulic analyses

    International Nuclear Information System (INIS)

    Chae, Hee Taek; Lee, Kye Hong

    1999-06-01

    MATRA-h, a HANARO subchannel analysis computer code, is used to evaluate thermal margin of the HANARO fuel. It's capability includes the assessments of CHF, ONB margin, and fuel temperature. In this report, basic input data and core design parameters required to perform the subchannel analysis with MATRA-h code are collected. These data include the subchannel geometric data, thermal-hydraulic correlations, empirical constants and material properties. The friction and form loss coefficients of the fuel assemblies were determined based on the results of the pressure drop test. At the same time, different form loss coefficients at the end plates and spacers are evaluated for various subchannels. The adequate correlations are applied to the evaluation of the form loss coefficients for various subchannels, which are corrected by measured values in order to have a same pressure drop at each flow channel. These basic input data and design parameters described in this report will be applied usefully to evaluate the thermal margin of the HANARO fuel. (author). 11 refs., 13 tabs., 11 figs

  15. Evaluation of properties and FEM Model of the Friction welded mild Steel-Al6061-Alumina

    Directory of Open Access Journals (Sweden)

    Hazman Seli

    2013-04-01

    Full Text Available Evaluation of mechanical and interfacial properties of friction welded alumina-mild steel rods with the use of Al6061 sheet are presented in this work. SEM, EDX analysis, hardness and bending strength tests were conducted. The bonds were attained through interfacial interlocking and intermetalllic phase formation with average bending strengths in the range of 40 to 200 MPa and insignificant hardness change in the parent alumina and mild steel. A preliminary simulation was made to predict the deformation, stress, strain and temperature distribution during the joining operation using a fully coupled thermo-mechanical FE model. The aluminum alloy metal being rubbed was simulated using a phenomenological Johnson-Cook viscoplasticity material model, which suited for materials subjected to large strains, high strain rates and high temperatures. The highest stress, strain and deformation are found to be within the heat affected zone of the weld close to the periphery rubbing surface region and correspond to the highest temperature profiles observed.

  16. Evaluation of properties and FEM Model of the Friction welded mild Steel-Al6061-Alumina

    Directory of Open Access Journals (Sweden)

    Hazman Seli

    2012-01-01

    Full Text Available Evaluation of mechanical and interfacial properties of friction welded alumina-mild steel rods with the use of Al6061 sheet are presented in this work. SEM, EDX analysis, hardness and bending strength tests were conducted. The bonds were attained through interfacial interlocking and intermetalllic phase formation with average bending strengths in the range of 40 to 200 MPa and insignificant hardness change in the parent alumina and mild steel. A preliminary simulation was made to predict the deformation, stress, strain and temperature distribution during the joining operation using a fully coupled thermo-mechanical FE model. The aluminum alloy metal being rubbed was simulated using a phenomenological Johnson-Cook viscoplasticity material model, which suited for materials subjected to large strains, high strain rates and high temperatures. The highest stress, strain and deformation are found to be within the heat affected zone of the weld close to the periphery rubbing surface region and correspond to the highest temperature profiles observed.

  17. 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

  18. Evaluation of the friction coefficient, the radial stress, and the damage work during needle insertions into agarose gels.

    Science.gov (United States)

    Urrea, Fabián A; Casanova, Fernando; Orozco, Gustavo A; García, José J

    2016-03-01

    Agarose hydrogels have been extensively used as a phantom material to mimic the mechanical behavior of soft biological tissues, e.g. in studies aimed to analyze needle insertions into the organs producing tissue damage. To better predict the radial stress and damage during needle insertions, this study was aimed to determine the friction coefficient between the material of commercial catheters and hydrogels. The friction coefficient, the tissue damage and the radial stress were evaluated at 0.2, 1.8, and 10mm/s velocities for 28, 30, and 32 gauge needles of outer diameters equal to 0.36, 0.31, and 0.23mm, respectively. Force measurements during needle insertions and retractions on agarose gel samples were used to analyze damage and radial stress. The static friction coefficient (0.295±0.056) was significantly higher than the dynamic (0.255±0.086). The static and dynamic friction coefficients were significantly smaller for the 0.2mm/s velocity compared to those for the other two velocities, and there was no significant difference between the friction coefficients for 1.8 and 10mm/s. Radial stress averages were 131.2±54.1, 248.3±64.2, and 804.9±164.3Pa for the insertion velocity of 0.2, 1.8, and 10mm/s, respectively. The radial stress presented a tendency to increase at higher insertion velocities and needle size, which is consistent with other studies. However, the damage work did not show to be a good predictor of tissue damage, which appears to be due to simplifications in the analytical model. Differently to other approaches, the method proposed here based on radial stress may be extended in future studies to quantity tissue damage in vivo along the entire needle track. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Mehanički gubici i mehanizam trenja u motorima SUS / Mechanical losses and the principle of friction in IC engines

    Directory of Open Access Journals (Sweden)

    Zoran B. Građin

    2003-01-01

    Full Text Available Savremene konstrukcije motora SUS treba da zadovolje zahtev za malu potrošnju goriva i ulja za podmazivanje, pre svega zbog ekoloških a zatim i energetskih i ekonomskih razloga. Pošto se pretpostavlja da će konvencionalni motori SUS još dugo dominirati kao pogonski agregati, raznim konstrukcionim merama pristupa se smanjenju potrošnje goriva, a time i smanjenju izduvne emisije. Pre svega, radi se o optimizaciji radnog ciklusa primeni varijabilnog stepena sabijanja, primeni varijabilnog razvoda radne materije, boljim sprezanjem sa gasnim mašinama, itd. Značajan potencijal za povećanje ekonomičnosti rada motora jeste u smanjenju mehaničkih gubitaka. Najveći udeo u mehaničkim gubicima predstavlja trenje po-kretnih delova motora, pre svega delova klipno-cilindarskog sklopa. Zbog toga se posebna pažnja posvećuje izučavanju mehanizma trenja, koji je inače veoma složen. / One of demands for modern designed IC engines is low fuel and lubricant consumption because of reasons concerning ecology as well as energy and economy. The symptom is that conventional IC engines will be the first choice as a power source for numerous applications in the future. Therefore many changes and improvements in design need to be done for further decrease of fuel consumption followed by the decrease of exhaust emission. First of all, there is the optimization of the working cycle, the application of variable compression, the application of variable valve control, better coupling with gas machines, etc. Significant potential for efficiency improvement of IC engines is in reducing mechanical losses. Mechanical losses in IC engines are caused mostly by friction between the mobile parts of the engine (piston-cylinder assembly. Therefore, continual attention to the research process of studying friction problems would be necessary.

  20. Experimental determination and evaluation of the friction behavior of geosynthetics; Experimentelle Ermittlung und Bewertung des Reibungsverhaltens von Geokunststoffen

    Energy Technology Data Exchange (ETDEWEB)

    Heinemann, Maik

    2016-08-17

    In many fields of geotechnical engineering geosynthetics have established itself as an alternative to common used earth materials. Particularly in landfill sealing systems many different types of geosynthetics are used together. In embankments geosynthetics form inclined planes. The safety against sliding must be proved for all contact surfaces. For this purpose, the knowledge of the friction behavior of the geosynthetics is required. Normally, the friction behavior is modeled analytically with the Coulomb failure criterion. The Coulomb friction parameters usually must be determined experimentally. In spite of the good state of the art and numerous studies into geosynthetics, in detail, there are still issues relating to the determination of friction behavior of geosynthetics, to the application of the Coulomb failure criterion and to the assessment of the friction parameters with a view to the time- and temperature-dependent behavior of synthetics. The main objective of this work is to contribute to a reliable determination of the friction behavior and to a correct assessment of the evaluated test results as the basis for a reliable and economical dimensioning of structures with geosynthetics. For this, the measurement technique of a standard large direct shear box was upgraded by the author, so that the effective normal stress can be measured below the test surface. Also tests with very small normal stresses can be carried out with this modification. Furthermore, a force-controlled test device was designed for studies of the influences arising from long-term combined compressive and shear loads and temperature. Based on experimental investigations inadequacies in the current experimental procedure are identified. In addition, the impact of factors are quantified, which are often ignored or considered to be marginal in practice. With further experimental investigations it is demonstrated that the linear Coulomb failure criterion is valid for limited normal stress

  1. Evaluation of Contact Friction in Fracture of Rotationally Bent Nitinol Endodontic Files

    Science.gov (United States)

    Haimed, Tariq Abu

    2011-12-01

    maximum strain amplitude (MSA) for each file size were determined based on images of the files inside the glass tubes. The force of insertion for each file type under each condition was also measured inside 45 and 60 degree glass tube paths, static and while dynamic. The results showed that NCF of Ni-Ti files is strongly inversely related to the CF which ranged from 0.15 for ODS and 3-HEPT coated files to 0.43 for irrigant bleach. High CF (in the presence of bleach) significantly reduced the NCF. Conversely, lower CF (in the presence of other solutions and file coatings) resulted in significantly higher NCF. CF was found to be directly related to the surface tension of the media used. Similarly, high MSA typical of low radius of curvature and high bending angle significantly diminished the fatigue life of Ni-Ti files. The integral of the force of insertion versus time curve was the highest for bleach irrigation which also showed the highest CF. Scanning electron microscope inspection of file fracture surfaces illustrated a 2-step progressive failure mode characterized by creation of a smooth initial fatigue area (striation marks) followed by catastrophic ductile fracture (dimple area) when the intact file shaft area was sufficiently reduced. The bleach-lubricated files failed earlier and with a smaller fatigue area (23%) than all other groups (31-35%) indicating premature fracture in the presence of higher frictional forces. The acquired data demonstrate that the combination of low MSA and low CF (by using coatings or solutions with low surface tension), related to the magnitude of the superficial drag force, can lead to statistically longer rotational bending lifetimes for Ni-Ti files. Based on the data of this study, lubricant solutions with low surface tension could significantly improve the fracture life of Ni-Ti files in root canal glass model. Laboratory testing using natural teeth should be performed to evaluate the effect of using such solutions on the fatigue

  2. Evaluating location specific strain rates, temperatures, and accumulated strains in friction welds through microstructure modeling

    Directory of Open Access Journals (Sweden)

    Javed Akram

    2018-04-01

    Full Text Available A microstructural simulation method is adopted to predict the location specific strain rates, temperatures, grain evolution, and accumulated strains in the Inconel 718 friction welds. Cellular automata based 2D microstructure model was developed for Inconel 718 alloy using theoretical aspects of dynamic recrystallization. Flow curves were simulated and compared with experimental results using hot deformation parameter obtained from literature work. Using validated model, simulations were performed for friction welds of Inconel 718 alloy generated at three rotational speed i.e., 1200, 1500, and 1500 RPM. Results showed the increase in strain rates with increasing rotational speed. These simulated strain rates were found to match with the analytical results. Temperature difference of 150 K was noticed from center to edge of the weld. At all the rotational speeds, the temperature was identical implying steady state temperature (0.89Tm attainment. Keywords: Microstructure modeling, Dynamic recrystallization, Friction welding, Inconel 718, EBSD, Hot deformation, Strain map

  3. Coefficient of friction of a starved lubricated spur gear pair

    International Nuclear Information System (INIS)

    Liu, Huaiju; Zhu, Caichao; Sun, Zhangdong; Zhang, Yuanyuan; Song, Chaosheng

    2016-01-01

    The frictional power loss issue of gear pairs becomes an important concern in both industry and academia due to the requirement of the energy saving and the improvement of power density of gear drives. A thermal starved elastohydrodynamic lubrication model is developed to study the tribological performance of a spur gear pair under starved lubrication conditions. The contact pressure, the film thickness, the temperature rise, the frictional power loss, as well as the coefficient of friction are evaluated by considering the variation of the curvature radius, the sliding/rolling motion, and the load distribution of gear tooth within the meshing period. Effects of lubrication starvation condition, load and speed on the coefficient of friction are studied.

  4. Evaluation of friction forces between control bars and guide tubes of CAREM fuel element

    International Nuclear Information System (INIS)

    Ghiselli, Alberto M.; Fiori, Jose M.; Yedros, Pablo A.

    2003-01-01

    The design of the MSAC (Mecanismo del Sistema de ajuste y control, Mechanism of the Adjustment and control system, MACS) for CAREM reactor shall consider all loads that the reactor shall support during its operation. Several charges are originated by friction forces produced on contact points of the control Bars/Guide tubes assembly against other components. A test facility was designed and manufactured for the determination of friction components and the damping characteristics of the assembly formed by guide tubes fuel element, the control bars and the guide of the bar of the MACS. In this work a description of the test performed and the results obtained is presented. (author)

  5. Microstructure Characterization and Stress Corrosion Evaluation of Autogenous and Hybrid Friction Stir Welded Al-Cu-Li 2195 Alloy

    Science.gov (United States)

    Li, Zhixian; Arbegast, William J.; Meletis, Efstathios I.

    1997-01-01

    Friction stir welding process is being evaluated for application on the Al-Cu-Li 2195 Super-Light Weight External Tank of the Space Transportation System. In the present investigation Al-Cu-Li 2195 plates were joined by autogenous friction stir welding (FSW) and hybrid FSW (friction stir welding over existing variable polarity plasma arc weld). Optical microscopy and transmission electron microscopy (TEM) were utilized to characterize microstructures of the weldments processed by both welding methods. TEM observations of autogenous FSW coupons in the center section of the dynamically-recrystallized zone showed an equiaxed recrystallized microstructure with an average grain size of approx. 3.8 microns. No T(sub 1), precipitates were present in the above-mentioned zone. Instead, T(sub B) and alpha precipitates were found in this zone with a lower population. Alternate immersion, anodic polarization, constant load, and slow strain tests were carried out to evaluate the general corrosion and stress-corrosion properties of autogenous and hybrid FSW prepared coupons. The experimental results will be discussed.

  6. Incisal Apical Root Resorption Evaluation after Low-Friction Orthodontic Treatment Using Two-Dimensional Radiographic Imaging and Trigonometric Correction.

    Science.gov (United States)

    Savoldi, Fabio; Bonetti, Stefano; Dalessandri, Domenico; Mandelli, Gualtiero; Paganelli, Corrado

    2015-11-01

    Root resorption shall be taken into consideration during every orthodontic treatment, and it can be effected by the use of different techniques, such as the application of low friction mechanics. However, its routinely assessment on orthopantomography has limitations related to distortions and changes in dental inclination. The aim of this investigation was to evaluate the severity of apical root resorption of maxillary and mandibular incisors after low-friction orthodontic treatment, using the combination of panoramic and lateral radiographs, and applying a trigonometric correction. A hospital based Retrospective study at the orthodontic Department (Dental School, University of Brescia, Spedali Civili di Brescia, Brescia, Italy). Ninety-three subjects (53 females and 40 males; mean age, 14 years) with mild teeth crowding were treated without extractions by the same operator using a low-friction fixed appliance following an integrated straight wire (ISW) protocol. The pre- and post-treatment tooth lengths of the maxillary and mandibular incisors were measured on panoramic radiographs. A trigonometric factor of correction for the pre-treatment length was calculated based on the difference between the pre and post-treatment incisal inclination on lateral cephalograms. The changes in lengths were investigated using the Student's t-test for paired values (proot development in younger patients, mandibular central and lateral incisors underwent slight resorption (-3.1%, -3.4%). A statistically significant difference was found for the mandibular incisors but not for the maxillary ones. In patients with mild crowding and consequent low amount of root movement, a low-friction orthodontic treatment can lead to slight apical root resorption, mainly involving lower incisors. The use of a trigonometric correction in the panoramic radiograph analysis may reduce the limitations of this 2D evaluation.

  7. Mode Specific Electronic Friction in Dissociative Chemisorption on Metal Surfaces: H2 on Ag(111)

    Science.gov (United States)

    Maurer, Reinhard J.; Jiang, Bin; Guo, Hua; Tully, John C.

    2017-06-01

    Electronic friction and the ensuing nonadiabatic energy loss play an important role in chemical reaction dynamics at metal surfaces. Using molecular dynamics with electronic friction evaluated on the fly from density functional theory, we find strong mode dependence and a dominance of nonadiabatic energy loss along the bond stretch coordinate for scattering and dissociative chemisorption of H2 on the Ag(111) surface. Exemplary trajectories with varying initial conditions indicate that this mode specificity translates into modulated energy loss during a dissociative chemisorption event. Despite minor nonadiabatic energy loss of about 5%, the directionality of friction forces induces dynamical steering that affects individual reaction outcomes, specifically for low-incidence energies and vibrationally excited molecules. Mode-specific friction induces enhanced loss of rovibrational rather than translational energy and will be most visible in its effect on final energy distributions in molecular scattering experiments.

  8. Evaluation of open-graded friction course mixture : technical assistance report.

    Science.gov (United States)

    2004-10-01

    Open-graded friction course (OGFC) is a porous, gap-graded, predominantly single size aggregate bituminous mixture that contains a high percentage of air voids. The high air void content and the open structure of this mix promote the effective draina...

  9. Adjustment of pipe flow explicit friction factor equations for application to tube bundles

    International Nuclear Information System (INIS)

    Wiltz, Christopher L.; Bowen, Mike D.; Von Olnhausen, Wayne A.

    2005-01-01

    Full text of publication follows: The accurate determination of single phase friction losses or friction pressure drop in tube bundles is essential in the thermal-hydraulic analyses of components such as nuclear fuel assemblies, heat exchangers and steam generators. Such friction losses are normally calculated using a friction factor, f, along with the experimental observation that the friction pressure drop in a pipe is proportional to the dynamic pressure (1/2 ρV 2 ) of the flow: ΔP = 1/2 ρV 2 (fL/D). In this equation L is the pipe or tube bundle length and D is the hydraulic diameter of the pipe or tube bundle. The friction factor is normally calculated using one of a number of explicit friction factor equations. A significant amount of work has been accomplished in developing explicit friction factor equations. These explicit equations range from approximations, which were developed for ease of numerical evaluation, to those which are mathematically complex but yield very good fits to the test data. These explicit friction factor equations are based on a large experimental data base, nearly all of which comes from pipe flow geometry information, and have been historically applied to tube bundles. This paper presents an adjustment method which may be applied to various explicit friction factor equations developed for pipe flow to accurately predict the friction factor for tube bundles. The characteristic of the adjustment is based on experimental friction pressure loss data obtained by Framatome ANP through flow testing of a nuclear fuel assembly (tube bundle) at its Richland Test Facility (RTF). Through adjustment of previously developed explicit friction factor equations for pipe flow, the vast amount of historical development and experimentation in the area of single phase pipe flow friction loss may be incorporated into the evaluation of single phase friction losses within tube bundles. Comparisons of the application of one or more of the previously

  10. Estimating productivity costs using the friction cost approach in practice: a systematic review.

    Science.gov (United States)

    Kigozi, Jesse; Jowett, Sue; Lewis, Martyn; Barton, Pelham; Coast, Joanna

    2016-01-01

    The choice of the most appropriate approach to valuing productivity loss has received much debate in the literature. The friction cost approach has been proposed as a more appropriate alternative to the human capital approach when valuing productivity loss, although its application remains limited. This study reviews application of the friction cost approach in health economic studies and examines how its use varies in practice across different country settings. A systematic review was performed to identify economic evaluation studies that have estimated productivity costs using the friction cost approach and published in English from 1996 to 2013. A standard template was developed and used to extract information from studies meeting the inclusion criteria. The search yielded 46 studies from 12 countries. Of these, 28 were from the Netherlands. Thirty-five studies reported the length of friction period used, with only 16 stating explicitly the source of the friction period. Nine studies reported the elasticity correction factor used. The reported friction cost approach methods used to derive productivity costs varied in quality across studies from different countries. Few health economic studies have estimated productivity costs using the friction cost approach. The estimation and reporting of productivity costs using this method appears to differ in quality by country. The review reveals gaps and lack of clarity in reporting of methods for friction cost evaluation. Generating reporting guidelines and country-specific parameters for the friction cost approach is recommended if increased application and accuracy of the method is to be realized.

  11. Friction Welding For Cladding Applications: Processing, Microstructure and Mechanical Properties of Inertia Friction Welds of Stainless Steel to Low Carbon Steel and Evaluation of Wrought and Welded Austenitic Stainless Steels for Cladding Applications in Acidchloride Service

    Science.gov (United States)

    Switzner, Nathan

    -state mixing. Thirdly, the corrosion resistance of multiple austenitic stainless steels (types 304, 316, and 309) processed in varying ways was compared for acid chloride environments using advanced electrochemical techniques. Physical simulation of fusion claddings and friction weld claddings (wrought stainless steels) was used for sample preparation to determine compositional and microstructural effects. Pitting resistance correlated firstly with Cr content, with N and Mo additions providing additional benefits. The high ferrite fraction of as-welded samples reduced their corrosion resistance. Wrought type 309L outperformed as-welded type 309L in dissolved mass loss and reverse corrosion rate from the potentiodynamic scan in 1.0 N HCl/3.5% NaCl solution. Electrochemical impedance results indicated that wrought 309L and 316L developed a corrosion resistant passive film more rapidly than other alloys in 0.1 N HCl/3.5% NaCl, and also performed well in long term (160-day) corrosion testing in the same environment. Fourthly, to prove the concept of internal CR lining by friction welding, a conical work piece of 304L stainless steel was friction welded internally to 1018 steel.

  12. [Criteria for forensic medical evaluation of professional working capacity loss].

    Science.gov (United States)

    Kapustin, A V; Tomilin, V V; Ol'khovik, V P; Panfilenko, O A; Serebriakova, V G

    2000-01-01

    The main and additional criteria used in evaluation (in percent) of loss of professional working capacity are characterized. Criteria common for forensic medical and medical social expert evaluations and differences between them are discussed. These differences are due to the fact that forensic medical expert evaluations are based on the Civil and Civil Processual Codes of the Russian Federation but not on the departamental norm-setting documents.

  13. Microplasticity and dislocation mobility in copper-nickel single crystals evaluated from strain-amplitude-dependent internal friction. [CuNi

    Energy Technology Data Exchange (ETDEWEB)

    Nishino, Y.; Okada, Y.; Asano, S. (Dept. of Materials Science and Engineering, Nagoya Inst. of Tech. (Japan))

    1992-02-16

    Internal friction in copper-0.4 to 7.6 at% nickel single crystals is measured as a function of strain amplitude at various temperatures. Analysis of the data on the amplitude-dependent internal friction yields the relation of effective stress and microplastic strain of the order of 10{sup -9}. The stress-strain responses thus obtained exhibit that the microplastic flow stress increases more rapidly on alloying than the macroscopic yield stress. The mean dislocation velocity is also evaluated from the internal-friction data, which corresponds well to the etch-pit data. It is shown that the dislocation motion is impeded by friction due to dispersed solute atoms. (orig.).

  14. 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.

  15. 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.

  16. Evaluation of Internal Friction versus Plastic Deformations Effects in Impact Dynamics Problems of Robotic Elements

    Directory of Open Access Journals (Sweden)

    Stelian Alaci

    2014-06-01

    Full Text Available The dynamical behavior study of robotic systems is obtained using multibody dynamics method. The joints met in robots are modeled in different manners. In a robotic joint the energy is lost via hysteretic work and plastic deformation work. The paper presents a comparative study for the results obtained by integration of the equations defining two limit models which describe the impact between two robot parts, modeled by the centric collision between two spheres with loss of energy. The motion equations characteristic for the two models are integrated and for a tangible situation, are presented comparatively, for different values of the coefficient of restitution, the time dependencies of impacting force between the two bodies as well as the hysteresis loops. Finally, an evaluation of the lost work during impact, for the whole range of coefficients of restitution, is completed, together with characteristic parameters of collision: approaching period, complete contact time, maximum approaching and plastic imprint.

  17. Heat Loss Evaluation of the SMART-ITL Primary System

    International Nuclear Information System (INIS)

    Ryu, Sung Uk; Bae, Hwang; Kim, Dong Eok; Park, Keun Tae; Park, Hyun Sik; Yi, Sung Jae

    2013-01-01

    It is considered that the heat loss rate is one of the critical factors affecting the transient behavior of an integral effect test facility. This paper presents the experimental results of the heat loss rate for the primary system of a SMART-ITL (System-Integrated Modular Advanced ReacTor-Integral Test Loop) facility including the pressurizer (PZR). To evaluate the heat loss rate of the primary system, two different approaches were pursued, i. e., integral and differential approaches. The integral approach is a constant temperature method which controls the core and PZR powers at a desired temperature condition and the differential approach is a natural cooling-down measurement method that lasts for a long period of time. In the present work, the heat losses derived from integral and differential approaches were acquired for the primary system of the SMART-ITL. The results obtained by the two approaches were very similar. In addition, an empirical correlation with respect to the difference between the wall temperature and the ambient temperature was proposed to represent the heat loss characteristics of the SMART-ITL facility. The estimated heat losses could be used to estimate the heat loss during the tests and code simulations

  18. An evaluation of prediction methods for frictional pressure drop of Two-phase flow in mini-channels

    International Nuclear Information System (INIS)

    Sun Licheng; Yan Changqi; Sun Zhongning

    2010-01-01

    2092 pieces of data for frictional pressure drop of two-phase flow were collected from 18 published papers of which the working fluids include R123, R134a, R22, R236ea, R245fa, R404a, R407C, R410a, R507, CO2, water and air. The hydraulic diameter ranges from 0.506 to 12 mm; Re l from 10 to 37000, and Re g from 3 to 4 x 10 5 . 11 correlations and models for calculating the frictional pressure drop of two-phase flow were evaluated based on these data. The results show that the accuracy of the Lockhart-Martinelli method, Mishima and Hibiki correlation, Zhang and Mishima correlation and Lee and Mudawar correlation in the laminar region is very close to each other, while the Muller-Steinhagen and Heck correlation is the best among the evaluated correlations in the turbulent region. New correlation based on Chishom method was proposed, which is better than other methods in both laminar region and turbulent region. (authors)

  19. Characteristic evaluation of process parameters of friction stir welding of aluminium 2024 hybrid composites

    Science.gov (United States)

    Sadashiva, M.; Shivanand, H. K.; Vidyasagar, H. N.

    2018-04-01

    The Current work is aimed to investigate the effect of process parameters in friction stir welding of Aluminium 2024 base alloy and Aluminium 2024 matrix alloy reinforced with E Glass and Silicon Carbide reinforcements. The process involved a set of synthesis techniques incorporating stir casting methodology resulting in fabrication of the composite material. This composite material that is synthesized is then machined to obtain a plate of dimensions 100 mm * 50 mm * 6 mm. The plate is then friction stir welded at different set of parameters viz. the spindle speed of 600 rpm, 900 rpm and 1200 rpm and feed rate of 40 mm/min, 80 mm/min and 120 mm/min for analyzing the process capability. The study of the given set of parameters is predominantly important to understand the physics of the process that may lead to better properties of the joint, which is very much important in perspective to its use in advanced engineering applications, especially in aerospace domain that uses Aluminium 2024 alloy for wing and fuselage structures under tension.

  20. Mechanical properties and microstructural evaluation of AA1100 to AZ31 dissimilar friction stir welds

    Energy Technology Data Exchange (ETDEWEB)

    Azizieh, M., E-mail: azizieh@gmail.com [Department of Materials Science and Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz (Iran, Islamic Republic of); Sadeghi Alavijeh, A. [School of Mechatronic Systems Engineering, Simon Fraser University, 250-13450 102 Avenue, Surrey, BC V3T 0A3 (Canada); Abbasi, M. [High Temperature Energy Materials, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of); Balak, Z. [Department of Materials Science and Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz (Iran, Islamic Republic of); Kim, H.S. [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang, 790-784 (Korea, Republic of)

    2016-02-15

    In this paper, microstructure and mechanical properties of dissimilar friction stir welds of AA1100 and AZ31 were investigated to understand the effects of rotational and travel speed as well as pin position. The tensile results of welded samples revealed that the sound welds were formed when the stirring pin deviated from the centreline to the AZ31 side. The X-ray diffraction shows that Al{sub 3}Mg{sub 2} and Al{sub 12}Mg{sub 17} intermetallics formation occurs in the stir zone during the welding process. High hardness of these intermetallic phases increased the hardness of the stir zone to 110 Hv. The best tensile results were obtained in the sample processed in the range of 28–32 (rev/mm) rotational to travel speed ratio. - Highlights: • For Al to Mg friction stir welding, tool offset must be to Mg side. • There is an optimum rotational speed for obtain the highest strength. • Intermetallics form in any welding condition. • The volume fraction of intermetallic is directly related to FSW peak temperature.

  1. Synergistic effect of tungsten disulfide and cenosphere combination on braking performance of composite friction materials

    International Nuclear Information System (INIS)

    Kachhap, Rakesh K.; Satapathy, Bhabani K.

    2014-01-01

    Graphical abstract: Graphical abstract showing correlation between enhanced frictional stability and enhanced visc-oelastic energy dissipation. - Highlights: • Developed new class of brake composites based on WS 2 and cenosphere. • Synergistic effect of WS 2 and cenosphere for enhanced friction stability. • Wear surface morphology revealed composition specific topography. • Friction fade-recovery performance remained optimal. - Abstract: Tungsten disulfide (WS 2 /TDS) based cenosphere (Cn) filled friction composites with varying cenosphere to WS 2 ratio (Cn/TDS) were fabricated by compression molding of phenolic resin based dry formulation mix and evaluated for their thermal, thermo-mechanical and tribological performances. The loss and revival of braking friction effectiveness due to heating or cooling of the disc termed as fade and recovery performance have been characterized on a Krauss friction testing machine following ECE R-90 industrial standards. The fade performance remained dependent on Cn/TDS, where enhanced fading could be correlated to lower Cn/TDS value accompanied with broader frictional fluctuations i.e. μ max –μ min . A decrease in the frictional-recovery response ensued with increase in Cn/TDS. Dynamic mechanical analysis revealed an increase in storage modulus till 2.5 wt.% of TDS loading followed by consistent decrease whereas two distinct peaks in loss modulus plots that are composition independent have been observed. Scanning electron microscopy revealed the worn surface morphology associated with the dynamics of contact patches formation and deformation vis-a-vis friction layer formation as integrally responsible for the observed friction performance. Energy dispersive analysis of X-rays (EDX) enabled compositional analysis of the friction layer viz. Fe, W, Si, and Al content which may have a mechanistic role in controlling phenomena like, disc rubbing, lubricity, porosity, and hardness of friction layer formed during braking

  2. Evaluation of Underwater Adhesives and Friction Coatings for In Situ Attachment of Fiber Optic Sensor System for Subsea Applications

    Science.gov (United States)

    Tang, Henry H.; Le, Suy Q.; Orndoff, Evelyne S.; Smith, Frederick D.; Tapia, Alma S.; Brower, David V.

    2012-01-01

    Integrity and performance monitoring of subsea pipelines and structures provides critical information for managing offshore oil and gas production operation and preventing environmentally damaging and costly catastrophic failure. Currently pipeline monitoring devices require ground assembly and installation prior to the underwater deployment of the pipeline. A monitoring device that could be installed in situ on the operating underwater structures could enhance the productivity and improve the safety of current offshore operation. Through a Space Act Agreement (SAA) between the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) and Astro Technology, Inc. (ATI), JSC provides technical expertise and testing facilities to support the development of fiber optic sensor technologies by ATI. This paper details the first collaboration effort between NASA JSC and ATI in evaluating underwater applicable adhesives and friction coatings for attaching fiber optic sensor system to subsea pipeline. A market survey was conducted to examine different commercial ]off ]the ]shelf (COTS) underwater adhesive systems and to select adhesive candidates for testing and evaluation. Four COTS epoxy based underwater adhesives were selected and evaluated. The adhesives were applied and cured in simulated seawater conditions and then evaluated for application characteristics and adhesive strength. The adhesive that demonstrated the best underwater application characteristics and highest adhesive strength were identified for further evaluation in developing an attachment system that could be deployed in the harsh subsea environment. Various friction coatings were also tested in this study to measure their shear strengths for a mechanical clamping design concept for attaching fiber optic sensor system. A COTS carbide alloy coating was found to increase the shear strength of metal to metal clamping interface by up to 46 percent. This study provides valuable data for

  3. Friction welding of AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tsujino, R.; Ochi, H. [Osaka Inst. of Tech., Osaka (Japan); Kawai, G. [Osaka Sangyo Univ., Osaka (Japan); Yamaguchi, H.; Ogawa, K. [Osaka Prefecture Univ., Osaka (Japan); Suga, Y. [Keio Univ., Kanagawa (Japan)

    2003-07-01

    In this paper, for an acceleration of utilization of magnesium alloy which is being interested in recent years, friction welding of AZ31 magnesium alloy was carried out, and the joint performance was discussed in relation to the deformation heat input in the upset stage and upset loss as a evaluation factor. Where, the deformation heat input in the upset stage is mechanical work represented by the product of upset speed and axial pressure. As a result, it was made clear that the friction welding of AZ31 magnesium alloy was easy in the atmosphere, and good welded joints without a non- adhesion area at the weld interface could de obtained. Moreover, the evaluation factors discussed were possible to evaluate to joint performance. (orig.)

  4. The Required Coefficient of Friction for evaluating gait alterations in people with Multiple Sclerosis during gait.

    Science.gov (United States)

    Pacifici, Ilaria; Galli, Manuela; Kleiner, Ana Francisca Rozin; Corona, Federica; Coghe, Giancarlo; Marongiu, Elisabetta; Loi, Andrea; Crisafulli, Antonio; Cocco, Eleonora; Marrosu, Maria Giovanna; Pau, Massimiliano

    2016-11-01

    Required Coefficient of Friction (RCOF) is one of the most critical gait parameters associated to the occurrence of slipping in individuals affected by neurological disorders characterized by balance impairments. This study aims to calculate RCOF in people with Multiple Sclerosis (MS) on the basis of three-dimensional Gait Analysis (GA) data. This study enrolls 22 people with MS (pwMS) who were characterized by an Expanded Disability Status Score in the range 1.5-6 and 10 healthy controls (HC). All participants underwent to three-dimensional GA from which we extracted kinematic and kinetic data (i.e. the Ground Reaction Forces, GRF, and joint moments and powers in the sagittal plane). RCOF was calculated as the ratio of the shear to normal GRF components during the stance phase of gait cycle, and normalized by the walking velocity. Thus, the following variables were extracted: first peak (named P1COF), valley (named V1COF), and second peak (named P2COF) in RCOF curve; also computating the maximum ankle dorsi-plantarflexion moment (MOMmax) and the maximum ankle joint power (PWRmax). Our data revealed that P2COF results are significantly lower in pwMS when compared to HC (p=0.043; Z=-2.025). In pwMS, the study found a moderate, positive correlation between V1COF and MOMmax (r=0.558; pFriction during mid stance and push off phases is critically important to determine whether the frictional capabilities of foot/floor interface are sufficient to prevent slips in pwMS. The impaired ankle moment in MS group causes increased P2COF in comparison to HC, increasing the risk of slipping in the critical phase of transmission of the developed forces to kinematic chain. Also, the correlation analysis among RCOF values and kinetic variables describe the interplay between V1COF and MOMmax: the higher V1COF is, the higher is MOMmax; and the different correlation the study found between COF and kinetic parameters in MS and HC group highlightes the different gait patterns of the two

  5. 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.

  6. Mechanical evaluation of linear friction welds in titanium alloys through indentation experiments

    International Nuclear Information System (INIS)

    Corzo, M.; Casals, O.; Alcala, J.; Mateo, A.; Anglada, M.

    2005-01-01

    This article shows the results of a project that focuses on the characterization of the weld interface region of dissimilar joints between titanium alloys for aeronautical applications, specifically Ti-6Al-2Sn-4Zr-6Mo with Ti-6Al-4V, and Ti-6Al-2Sn-4Zr-6Mo with Ti-6Al-2Sn-4Zr-2Mo. The uniaxial flow stress and hardening response of the material containing the weld were analyzed following the finite elements simulations and mathematical formulations to correlate hardness and the amount of pile-up and sinking-in phenomena around sharp indenters with uniaxial mechanical properties. This allows to accurately stablishing the influence that welding process has on the mechanical response of the parts. Tests performed on these friction-welded specimens showed that the fine grained microstructures in the welds exhibited better properties than the base materials. (Author) 12 refs

  7. Effects of Si3+ and H+ Irradiation on Tungsten Evaluated by Internal Friction Method

    International Nuclear Information System (INIS)

    Hu Jing; Wang Xianping; Fang Qianfeng; Liu Changsong; Zhang Yanwen; Zhao Ziqiang

    2013-01-01

    Effects of Si 3+ and H + irradiation on tungsten were investigated by internal friction (IF) technique. Scanning electron microscope (SEM) analysis revealed that sequential dual Si+H irradiation resulted in more serious damage than single Si irradiation. After irradiation, the IF background was significantly enhanced. Besides, two obvious IF peaks were initially found in temperature range of 70∼330 K in the sequential Si+H irradiated tungsten sample. The mechanism of increased IF background for the irradiated samples was suggested to originate from the high density dislocations induced by ion irradiation. On the other hand, the relaxation peak P L and non-relaxation peak P H in the Si+H irradiated sample were ascribed to the interaction process of hydrogen atoms with mobile dislocations and transient processes of hydrogen redistribution, respectively. The obtained experimental results verified the high sensitivity of IF method on the irradiation damage behaviors in nuclear materials

  8. Economic evaluation of losses: technique and use of data

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, T.K.; Drury, A.K.

    1992-01-01

    The paper reviews a major energy company's experience of the evaluation of the economic effects of accidents, discusses techniques for measurement and gives examples of current management use of the data. In 1988, British Petroleum carried out a pilot study at one of its coal mines in Illinois to investigate the direct cost of losses due to accidents to people, plant and equipment. It was found that the costs of losses were large (and in the case of the oil related studies the potential for loss was very large) and relatively easy to measure. However the use of the data to assist the effective management of operations required careful consideration. The paper concludes that measurement of the economic effect of accidents could be helpful to coal mining operations, but the correct organisational environment must be in place first. 3 figs., 6 tabs.

  9. Methodology to predict friction pressure drop in drilling fluid flows; Metodologia para previsao de perdas de carga em escoamentos de fluidos de perfuracao

    Energy Technology Data Exchange (ETDEWEB)

    Scheid, Claudia Miriam; Calcada, Luis Americo [Universidade Federal Rural do Rio de Janeiro (UFRRJ). Departamento de Engenharia Quimica (Brazil)], e-mails: scheid@ufrrj.br, calcada@ufrrj.br; Rocha, Daniele Cristine [Centro de Pesquisas da Petrobras (CENPES). Engenharia Basica de Abastecimento - Gas e Energia (Brazil)], e-mail: drocha@petrobras.com.br; Aranha, Pedro Esteves [Centro de Pesquisas da Petrobras (CENPES). Gerencia de Perfuracao e Completacao de Pocos (Brazil)], e-mail: pearanha@petrobras.com.br; Aragao, Atila Fernando Lima [E and P Construcao de Pocos Maritimos. Gerencia de Tecnologia de Fluidos (Brazil)], e-mail: atila_aragao@petrobras.com.br

    2009-12-15

    An extensive experimental study is detailed to evaluate the friction pressure drop resulting from the flow through pipe and annular sections, accessories such as tool joints, bit jets and stabilizers of four different drilling fluids used in deep water operations. After a data analysis process, it was possible to compile a set of equations to predict relevant hydraulic friction pressure loss calculations, such as: hydraulic diameter for annular flows, friction factors for pipe and annular turbulent flows and discharge coefficients for accessories. (author)

  10. Nonlinear friction model for servo press simulation

    Science.gov (United States)

    Ma, Ninshu; Sugitomo, Nobuhiko; Kyuno, Takunori; Tamura, Shintaro; Naka, Tetsuo

    2013-12-01

    The friction coefficient was measured under an idealized condition for a pulse servo motion. The measured friction coefficient and its changing with both sliding distance and a pulse motion showed that the friction resistance can be reduced due to the re-lubrication during unloading process of the pulse servo motion. Based on the measured friction coefficient and its changes with sliding distance and re-lubrication of oil, a nonlinear friction model was developed. Using the newly developed the nonlinear friction model, a deep draw simulation was performed and the formability was evaluated. The results were compared with experimental ones and the effectiveness was verified.

  11. Evaluation of friction heating in cavitating high pressure Diesel injector nozzles

    Science.gov (United States)

    Salemi, R.; Koukouvinis, P.; Strotos, G.; McDavid, R.; Wang, Lifeng; Li, Jason; Marengo, M.; Gavaises, M.

    2015-12-01

    Variation of fuel properties occurring during extreme fuel pressurisation in Diesel fuel injectors relative to those under atmospheric pressure and room temperature conditions may affect significantly fuel delivery, fuel injection temperature, injector durability and thus engine performance. Indicative results of flow simulations during the full injection event of a Diesel injector are presented. In addition to the Navier-Stokes equations, the enthalpy conservation equation is considered for predicting the fuel temperature. Cavitation is simulated using an Eulerian-Lagrangian cavitation model fully coupled with the flow equations. Compressible bubble dynamics based on the R-P equation also consider thermal effects. Variable fuel properties function of the local pressure and temperature are taken from literature and correspond to a reference so-called summer Diesel fuel. Fuel pressurisation up to 3000bar pressure is considered while various wall temperature boundary conditions are tested in order to compare their effect relative to those of the fuel heating caused during the depressurisation of the fuel as it passes through the injection orifices. The results indicate formation of strong temperature gradients inside the fuel injector while heating resulting from the extreme friction may result to local temperatures above the fuel's boiling point. Predictions indicate bulk fuel temperature increase of more than 100°C during the opening phase of the needle valve. Overall, it is concluded that such effects are significant for the injector performance and should be considered in relevant simulation tools.

  12. Evaluation of frictional resistance and surface characteristics after immersion of orthodontic brackets and wire in different chemical solutions: A comparative in vitrostudy.

    Science.gov (United States)

    Nanjundan, Kavitha; Vimala, G

    2016-01-01

    To evaluate the changes of static and kinetic frictional forces between the brackets and wires following exposure to a soft drink, acidic food ingredient, and acidulated fluoride prophylactic agents. Two types of Roth prescription mandibular incisor brackets were used: 3M Unitek Victory stainless steel (SS) brackets (n = 40) and Transcend 6000 polycrystalline alumina (PCA) brackets (n = 40) as well as eighty 0.019 × 0.025" dimension ortho technology SS wires of 50 mm length each. Subsequently, brackets tied with SS wires divided into eight subgroups (n = 10) and were immersed in vinegar (pH = 3.5 ± 0.5), Pepsi ® (pH = 2.46), Colgate Phos-Flur mouth rinse (pH = 5.1), and artificial saliva (control group pH = 7) for 24 h. Changes in surface morphology under scanning electron microscope ×1000, surface roughness (Ra) with surface profilometer (single bracket and single wire from each subgroup), and frictional resistance using universal testing machine were evaluated. Highest mean (standard deviation) static frictional force of 2.65 (0.25) N was recorded in Pepsi ® followed by 2.57 (0.25) N, 2.40 (0.22) N, and 2.36 (0.17) N for Vinegar, Colgate Phos-Flur mouth rinse, and artificial saliva groups, respectively. In a similar order, lesser mean kinetic frictional forces obtained. PCA brackets revealed more surface deterioration and higher frictional force values than SS brackets. A significant positive correlation was observed between frictional forces and bracket slot roughness (r = 0.861 and 0.802, respectively, for static and kinetic frictional forces, p < 0.001 for both) and wire roughness (r = 0.243 and 0.242, respectively, for static and kinetic frictional forces, p < 0.05 for both). Findings may have long-term implications when acidic food substances are used during fixed orthodontic treatment. Further, in vivo studies are required to analyze the clinical effect of acidic mediums in the oral environment during orthodontic treatment.

  13. Evaluation of frictional resistance and surface characteristics after immersion of orthodontic brackets and wire in different chemical solutions: A comparative in vitrostudy

    Directory of Open Access Journals (Sweden)

    Kavitha Nanjundan

    2016-01-01

    Full Text Available Aim: To evaluate the changes of static and kinetic frictional forces between the brackets and wires following exposure to a soft drink, acidic food ingredient, and acidulated fluoride prophylactic agents. Materials and Methods: Two types of Roth prescription mandibular incisor brackets were used: 3M Unitek Victory stainless steel (SS brackets (n = 40 and Transcend 6000 polycrystalline alumina (PCA brackets (n = 40 as well as eighty 0.019 × 0.025" dimension ortho technology SS wires of 50 mm length each. Subsequently, brackets tied with SS wires divided into eight subgroups (n = 10 and were immersed in vinegar (pH = 3.5 ± 0.5, Pepsi ® (pH = 2.46, Colgate Phos-Flur mouth rinse (pH = 5.1, and artificial saliva (control group pH = 7 for 24 h. Changes in surface morphology under scanning electron microscope ×1000, surface roughness (Ra with surface profilometer (single bracket and single wire from each subgroup, and frictional resistance using universal testing machine were evaluated. Results: Highest mean (standard deviation static frictional force of 2.65 (0.25 N was recorded in Pepsi ® followed by 2.57 (0.25 N, 2.40 (0.22 N, and 2.36 (0.17 N for Vinegar, Colgate Phos-Flur mouth rinse, and artificial saliva groups, respectively. In a similar order, lesser mean kinetic frictional forces obtained. PCA brackets revealed more surface deterioration and higher frictional force values than SS brackets. A significant positive correlation was observed between frictional forces and bracket slot roughness (r = 0.861 and 0.802, respectively, for static and kinetic frictional forces, p < 0.001 for both and wire roughness (r = 0.243 and 0.242, respectively, for static and kinetic frictional forces, p < 0.05 for both. Conclusions: Findings may have long-term implications when acidic food substances are used during fixed orthodontic treatment. Further, in vivo studies are required to analyze the clinical effect of acidic mediums in the oral environment during

  14. A numerically research on energy loss evaluation in a centrifugal pump system based on local entropy production method

    Directory of Open Access Journals (Sweden)

    Hou Hucan

    2017-01-01

    Full Text Available Inspired by wide application of the second law of thermodynamics to flow and heat transfer devices, local entropy production analysis method was creatively introduced into energy assessment system of centrifugal water pump. Based on Reynolds stress turbulent model and energy equation model, the steady numerical simulation of the whole flow passage of one IS centrifugal pump was carried out. The local entropy production terms were calculated by user defined functions, mainly including wall entropy production, turbulent entropy production, and viscous entropy production. The numerical results indicated that the irreversible energy loss calculated by the local entropy production method agreed well with that calculated by the traditional method but with some deviations which were probably caused by high rotatability and high curvature of impeller and volute. The wall entropy production and turbulent entropy production took up large part of the whole entropy production about 48.61% and 47.91%, respectively, which indicated that wall friction and turbulent fluctuation were the major factors in affecting irreversible energy loss. Meanwhile, the entropy production rate distribution was discussed and compared with turbulent kinetic energy dissipation rate distribution, it showed that turbulent entropy production rate increased sharply at the near wall regions and both distributed more uniformly. The blade region in leading edge near suction side, trailing edge and volute tongue were the main regions to generate irreversible exergy loss. This research broadens a completely new view in evaluating energy loss and further optimizes pump using entropy production minimization.

  15. Friction dampers, the positive side of friction

    NARCIS (Netherlands)

    Lopez Arteaga, I.; Nijmeijer, H.; Busturia, J.M.; Sas, P.; Munck, de M.

    2004-01-01

    Friction is frequently seen as an unwanted phenomenon whose influence has to be either minimised or controlled. In this work one of the positive sides of friction is investigated: friction damping. Friction dampers can be a cheap and efficient way to reduce the vibration levels of a wide range of

  16. 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.

  17. A comparative study to evaluate the effects of ligation methods on friction in sliding mechanics using 0.022" slot brackets in dry state: An In-vitro study.

    Science.gov (United States)

    Vinay, K; Venkatesh, M J; Nayak, Rabindra S; Pasha, Azam; Rajesh, M; Kumar, Pradeep

    2014-04-01

    Friction between archwires and brackets is assuming greater importance for finishing with increased use of sliding mechanics in orthodontics as friction impedes the desired tooth movement. The following study is conducted to compare and evaluate the effect of ligation on friction in sliding mechanics using 0.022" slot bracket in dry condition. In the study 48 combinations of brackets, archwires and different ligation techniques were tested in order to provide best combination that offers less friction during sliding mechanics. Instron- 4467 machine was used to evaluate static and kinetic friction force values and the results were subjected to Statistical Analysis and Anova test. The results of the study showed that 0.022" metal brackets, Stainless steel wires and Slick modules provided the optimum frictional resistance to sliding mechanics. It is observed that frictional forces of 0.019" x 0.025" were higher when compared with 0.016" x 0.022" Stainless steel archwire due to the increase in dimension. Self-ligating brackets offered least friction followed by mini twin, variable force, regular stainless steel, ceramic with metal insert bracket and ceramic brackets. The stainless steel ligature offered less resistance than slick and grey modules, and TMA wires recorded maximum friction. The stainless steel archwire of 0.019" x 0.025" dimension are preferred during sliding mechanics, these archwires with variable force brackets ligated with Slick Modules offer decreased friction and is cost effective combination which can be utilized during sliding mechanics. How to cite the article: Vinay K, Venkatesh MJ, Nayak RS, Pasha A, Rajesh M, Kumar P. A comparative study to evaluate the effects of ligation methods on friction in sliding mechanics using 0.022" slot brackets in dry state: An In-vitro study. J Int Oral Health 2014;6(2):76-83.

  18. Effect of Sodium Fluoride Mouthwash on the Frictional Resistance of Orthodontic Wires

    Directory of Open Access Journals (Sweden)

    Allahyar Geramy

    2017-12-01

    Full Text Available Objectives: The friction between the brackets and orthodontic wire during sliding mechanics inflicts difficulties such as decreasing the applied force and tooth movement and also the loss of anchorage. Therefore, many studies have focused on the factors that affect the friction. The purpose of this study was to assess the effect of 0.05% sodium fluoride mouthwash on the friction between orthodontic brackets and wire.Materials and Methods: Four types of orthodontic wires including rectangular standard stainless steel (SS, titanium molybdenum alloy (TMA, nickel-titanium (NiTi and copper-nickel-titanium (Cu-NiTi were selected. In each group, half of the samples were immersed in 0.05% sodium fluoride mouthwash and the others were immersed in artificial saliva for 10 hours. An elastomeric ligature was used for ligating the wires to brackets. The frictional test was performed in a universal testing machine at the speed of 10 mm/minute. Two-way ANOVA was used for statistical analysis of the friction rate.Results: The friction rate was significantly higher after immersion in 0.05% sodium fluoride mouthwash in comparison with artificial saliva (P=0.00. Cu-NiTi wire showed the highest friction value followed by TMA, NiTi and SS wires.  Conclusions: According to the results of the current study, 0.05% sodium fluoride mouthwash increased the frictional characteristics of all the evaluated orthodontic wires.

  19. Evaluation of long-term pavement performance and noise characteristics of open-graded friction courses : project 2.

    Science.gov (United States)

    2012-06-01

    This report describes the second of three experimental installations of open-graded friction course (OGFC) quieter pavements designed to reduce the noise generated at the tire/pavement interface. Experimental sections of OGFC were built using a...

  20. 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.

  1. An in vitro Evaluation of Friction Characteristics of Conventional Stainless Steel and Self-ligating Stainless Steel Brackets with different Dimensions of Archwires in Various Bracket-archwire Combination.

    Science.gov (United States)

    Sridharan, K; Sandbhor, Shailesh; Rajasekaran, U B; Sam, George; Ramees, M Mohamed; Abraham, Esther A

    2017-08-01

    The purpose of this research is to compare the frictional attributes of stainless steel conventional brackets and self-ligating stainless steel brackets with different dimensions of archwires. The test was carried with two sets of maxillary brackets: (1) Conventional stainless steel (Victory Series), (2) stainless steel self-ligating (SmartClip) without first premolar brackets. Stainless steel, nickel-titanium (NiTi), and beta-Ti which are the types of orthodontic wire alloys were tested in this study. To monitor the frictional force, a universal testing machine (Instron 33R 4467) that comprises 10 kg tension load cell was assigned on a range of 1 kg and determined from 0 to 2 kg, which allows moving of an archwire along the brackets. One-way analysis of variance was used to test the difference between groups. To analyze the statistical difference between the two groups, Student's t-test was used. For Victory Series in static friction, p-value was 0.946 and for kinetic friction it was 0.944; at the same time for SmartClip, the p value for static and kinetic frictional resistance was 0.497 and 0.518 respectively. Hence, there was no statistically significant difference between the NiTi and stainless steel archwires. It is concluded that when compared with conventional brackets with stainless steel ligatures, self-ligating brackets can produce significantly less friction during sliding. Beta-Ti archwires expressed high amount of frictional resistance and the stainless steel archwires comprise low frictional resistance among all the archwire materials. In orthodontics, frictional resistance has always had a major role. Its ability to impair tooth movement leads to the need for higher forces to move the teeth and it extends the treatment time which results in loss of posterior anchorage. Friction in orthodontics is related with sliding mechanics when a wire is moving through one or a series of bracket slots.

  2. Vacuum friction

    Science.gov (United States)

    Barnett, Stephen M.; Sonnleitner, Matthias

    2018-03-01

    We know that in empty space there is no preferred state of rest. This is true both in special relativity but also in Newtonian mechanics with its associated Galilean relativity. It comes as something of a surprise, therefore, to discover the existence a friction force associated with spontaneous emission. The resolution of this paradox relies on a central idea from special relativity even though our derivation of it is non-relativistic. We examine the possibility that the physics underlying this effect might be explored in an ion trap, via the observation of a superposition of different mass states.

  3. Frequency-dependent friction and its significance for liquid pipeline simulation; Influencia do fator de atrito com dependencia da frequencia na simulacao de transientes em oleodutos

    Energy Technology Data Exchange (ETDEWEB)

    Tepedino, Alexandre F. [TRANSPETRO - PETROBRAS Transporte S.A., Rio de Janeiro, RJ (Brazil); Rachid, Felipe B. Freitas [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica. Lab. de Transporte de Liquidos e Gases

    2008-07-01

    Unsteady liquid flow in pipelines is usually described by using one-dimensional models and, in a procedure referred to as quasi-steady approximation, friction losses are estimated by formulae derived for steady state flow conditions. The assumption is that the friction loss during transient flow conditions can be approximated by the friction loss obtained for a steady flow with the same average velocity. However, during unsteady flow conditions the velocity profile can be considerably different from the steady flow. The shear stress at the pipe wall and the mean velocity are not in phase. Therefore, friction losses computed according to the quasi-steady approximation are inaccurate. To overcome this, the concept of frequency-dependent friction was proposed, including the time history of the mean flow velocity and acceleration, resulting in better correlation to experimental data. This work presents an investigation of situations in which the use of a frequency-dependent friction model could bring additional improvement for the petroleum and products pipeline simulation. To do so, through computer simulations, the predictions of both quasi-steady and unsteady friction models, for short and long lines, operating under a range of Reynolds numbers, are compared and the significance of the friction model is evaluated. (author)

  4. Field Evaluation of Cereal Combine Harvesters Processing Losses on JD-955 and JD-1165 Combines Equipped with Grain Loss Monitor

    Directory of Open Access Journals (Sweden)

    M.R Mostofi Sarkari

    2014-09-01

    Full Text Available Grain loss monitors are installed on combine harvester and make it possible to measure grain loss on different parts of the combine. The instrument permits the operator to adjust a proper ground speed to keep grain loss within an acceptable range. In this study a loss monitoring system was implemented to measure grain losses continuously on straw walker and sieves. Two grain loss monitors (KEE and TeeJet were installed behind the straw walker and the sieves of JD-955 and JD-1165 combine harvesters. Harvesting performance parameters such as combine total and processing losses were then measured. To evaluate the precision and accuracy of the instruments, the measured and monitored losses were compared and investigated. The results of a two-year research showed that the average processing loss of the combine harvesters with 10-12% grain moisture content and 750 rpm drum speed was 0.82% which is whitin the acceptable range recommended by ASAE Standard No. S343.3. Furthermore, there was no significant difference between the measured and monitored values of processing loss.

  5. Seismic Response and Evaluation of SDOF Self-Centering Friction Damping Braces Subjected to Several Earthquake Ground Motions

    Directory of Open Access Journals (Sweden)

    Jong Wan Hu

    2015-01-01

    Full Text Available This paper mainly deals with seismic response and performance for self-centering friction damping braces (SFDBs subjected to several maximum- or design-leveled earthquake ground motions. The self-centering friction damping brace members consist of core recentering components fabricated with superelastic shape memory alloy wires and energy dissipation devices achieved through shear friction mechanism. As compared to the conventional brace members for use in the steel concentrically braced frame structure, these self-centering friction damping brace members make the best use of their representative characteristics to minimize residual deformations and to withstand earthquake loads without member replacement. The configuration and response mechanism of self-centering friction damping brace systems are firstly described in this study, and then parametric investigations are conducted through nonlinear time-history analyses performed on numerical single degree-of-freedom spring models. After observing analysis results, adequate design methodologies that optimally account for recentering capability and energy dissipation according to their comparative parameters are intended to be suggested in order to take advantage of energy capacity and to minimize residual deformation simultaneously.

  6. Weight loss versus muscle loss: re-evaluating inclusion criteria for future cancer cachexia interventional trials.

    Science.gov (United States)

    Roeland, Eric J; Ma, Joseph D; Nelson, Sandahl H; Seibert, Tyler; Heavey, Sean; Revta, Carolyn; Gallivan, Andrea; Baracos, Vickie E

    2017-02-01

    Participation in cancer cachexia clinical trials requires a defined weight loss (WL) over time. A loss in skeletal muscle mass, measured by cross-sectional computed tomography (CT) image analysis, represents a possible alternative. Our aim was to compare WL versus muscle loss in patients who were screened to participate in a cancer cachexia clinical trial. This was a single-center, retrospective analysis in metastatic colorectal cancer patients screened for an interventional cancer cachexia trial requiring a ≥5 % WL over the preceding 6 months. Concurrent CT images obtained as part of standard oncology care were analyzed for changes in total muscle and fat (visceral, subcutaneous, and total). Of patients screened (n = 36), 3 (8 %) enrolled in the trial, 17 (47 %) were excluded due to insufficient WL (20 %), and 16 (44 %) met inclusion criteria for WL. Patients who met screening criteria for WL (5-20 %) had a mean ± SD of 7.7 ± 8.7 % muscle loss, 24.4 ± 37.5 % visceral adipose loss, 21.6 ± 22.3 % subcutaneous adipose loss, and 22.1 ± 24.7 % total adipose loss. Patients excluded due to insufficient WL had 2 ± 6.4 % muscle loss, but a gain of 8.5 ± 39.8 % visceral adipose, and 4.2 ± 28.2 % subcutaneous adipose loss and 0.8 ± 28.4 % total adipose loss. Of the patients excluded due to WL 5 %. Defining cancer cachexia by WL over time may be limited as it does not capture skeletal muscle loss. Cross-sectional CT body composition analysis may improve early detection of muscle loss and patient participation in future cancer cachexia clinical trials.

  7. Estimation of parasitic losses in a proposed mesoscale resonant engine: Experiment and model

    Science.gov (United States)

    Preetham, B. S.; Anderson, M.; Richards, C.

    2014-02-01

    A resonant engine in which the piston-cylinder assembly is replaced by a flexible cavity is realized at the mesoscale using flexible metal bellows to demonstrate the feasibility of the concept. A four stroke motoring technique is developed and measurements are performed to determine parasitic losses. A non-linear lumped parameter model is developed to evaluate the engine performance. Experimentally, the heat transfer and friction effects are separated by varying the engine speed and operating frequency. The engine energy flow diagram showing the energy distribution among various parasitic elements reveals that the friction loss in the bellows is smaller than the sliding friction loss in a typical piston-cylinder assembly.

  8. An Evaluation of Global and Local Tensile Properties of Friction-Stir Welded DP980 Dual-Phase Steel Joints Using a Digital Image Correlation Method.

    Science.gov (United States)

    Lee, Hyoungwook; Kim, Cheolhee; Song, Jung Han

    2015-12-04

    The effect of the microstructure heterogeneity on the tensile plastic deformation characteristic of friction-stir-welded (FSW) dual-phase (DP) steel was investigated for the potential applications on the lightweight design of vehicles. Friction-stir-welded specimens with a butt joint configuration were prepared, and quasi-static tensile tests were conducted, to evaluate the tensile properties of DP980 dual-phase steels. The friction-stir welding led to the formation of martensite and a significant hardness rise in the stir zone (SZ), but the presence of a soft zone in the heat-affected zone (HAZ) was caused by tempering of the pre-existing martensite. Owing to the appearance of severe soft zone, DP980 FSW joint showed almost 93% joint efficiency with the view-point of ultimate tensile strength and relatively low ductility than the base metal (BM). The local tensile deformation characteristic of the FSW joints was also examined using the digital image correlation (DIC) methodology by mapping the global and local strain distribution, and was subsequently analyzed by mechanics calculation. It is found that the tensile deformation of the FSW joints is highly heterogeneous, leading to a significant decrease in global ductility. The HAZ of the joints is the weakest region where the strain localizes early, and this localization extends until fracture with a strain near 30%, while the strain in the SZ and BM is only 1% and 4%, respectively. Local constitutive properties in different heterogeneous regions through the friction-stir-welded joint was also briefly evaluated by assuming iso-stress conditions. The local stress-strain curves of individual weld zones provide a clear indication of the heterogeneity of the local mechanical properties.

  9. Economic evaluation of water loss saving due to the biological ...

    African Journals Online (AJOL)

    This paper focuses on water loss saving as the benefit derived from biological control of this plant between 1990 and 2013 at New Year's Dam, Alicedale, Eastern Cape, South Africa. Estimates of water loss due to evapotranspiration from water hyacinth vary significantly; therefore, the study used three different rates, high, ...

  10. 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.

  11. Intra-Wellbore Head Losses in a Horizontal Well with both Kinematic and Frictional Effects in an Anisotropic Confined Aquifer between Two Streams

    Science.gov (United States)

    Wang, Q.; Zhan, H.

    2017-12-01

    Horizontal drilling becomes an appealing technology for water exploration or aquifer remediation in recent decades, due to the decreasing operational cost and many technical advantages over the vertical wells. However, many previous studies on the flow into horizontal wells were based on the uniform flux boundary condition (UFBC) for treating horizontal wells, which could not reflect the physical processes of flow inside the well accurately. In this study, we investigated transient flow into a horizontal well in an anisotropic confined aquifer between two streams for three types of boundary conditions of treating the horizontal well, including UFBC, uniform head boundary condition (UHBC), and mixed-type boundary condition (MTBC). The MTBC model considered both kinematic and frictional effects inside the horizontal well, in which the kinematic effect referred to the accelerational and fluid inflow effects. The new solution of UFBC was derived by superimposing the point sink/source solutions along the axis of the horizontal well with a uniform strength. The solutions of UHBC and MTBC were obtained by a hybrid analytical-numerical method, and an iterative method was proposed to determine the minimum well segment number required to yield sufficiently accurate answer. The results showed that the differences among the UFBC, UHBC, MTBCFriction and MTBC solutions were obvious, in which MTBCFriction represented the solutions considering the frictional effect but ignoring the kinematic effect. The MTBCFriction and MTBC solutions were sensitive to the flow rate, and the difference of these two solutions increases with the flow rate, suggesting that the kinematic effect could not be ignored for studying flow to a horizontal well, especially when the flow rate is great. The well specific inflow (WSI) (which is the inflow per unit screen length at a specified location of the horizontal well) increased with the distance along the wellbore for the MTBC model at early stage, while

  12. Friction behavior of ceramic injection-molded (CIM) brackets.

    Science.gov (United States)

    Reimann, Susanne; Bourauel, Christoph; Weber, Anna; Dirk, Cornelius; Lietz, Thomas

    2016-07-01

    Bracket material, bracket design, archwire material, and ligature type are critical modifiers of friction behavior during archwire-guided movement of teeth. We designed this in vitro study to compare the friction losses of ceramic injection-molded (CIM) versus pressed-ceramic (PC) and metal injection-molded (MIM) brackets-used with different ligatures and archwires-during archwire-guided retraction of a canine. Nine bracket systems were compared, including five CIM (Clarity™ and Clarity™ ADVANCED, both by 3M Unitek; discovery(®) pearl by Dentaurum; Glam by Forestadent; InVu by TP Orthodontics), two PC (Inspire Ice by Ormco; Mystique by DENTSPLY GAC), and two MIM (discovery(®) and discovery(®) smart, both by Dentaurum) systems. All of these were combined with archwires made of either stainless steel or fiberglass-reinforced resin (remanium(®) ideal arch or Translucent pearl ideal arch, both by Dentaurum) and with elastic ligatures or uncoated or coated stainless steel (all by Dentaurum). Archwire-guided retraction of a canine was simulated with a force of 0.5 N in the orthodontic measurement and simulation system (OMSS). Friction loss was determined by subtracting the effective orthodontic forces from the applied forces. Based on five repeated measurements performed on five brackets each, weighted means were calculated and evaluated by analysis of variance and a Bonferroni post hoc test with a significance level of 0.05. Friction losses were significantly (p brackets used with a stainless-steel ligature and the resin archwire. No critical difference to friction behavior was apparent between the various manufacturing technologies behind the bracket systems.

  13. Evaluation of stator core loss of high speed motor by using thermography camera

    Science.gov (United States)

    Sato, Takeru; Enokizono, Masato

    2018-04-01

    In order to design a high-efficiency motor, the iron loss that is generated in the motor should be reduced. The iron loss of the motor is generated in a stator core that is produced with an electrical steel sheet. The iron loss characteristics of the stator core and the electrical steel sheet are agreed due to a building factor. To evaluate the iron loss of the motor, the iron loss of the stator core should be measured more accurately. Thus, we proposed the method of the iron loss evaluation of the stator core by using a stator model core. This stator model core has been applied to the surface mounted permanent magnet (PM) motors without windings. By rotate the permanent magnet rotor, the rotating magnetic field is generated in the stator core like a motor under driving. To evaluate the iron loss of the stator model core, the iron loss of the stator core can be evaluated. Also, the iron loss can be calculated by a temperature gradient. When the temperature gradient is measured by using thermography camera, the iron loss of entire stator core can be evaluated as the iron loss distribution. In this paper, the usefulness of the iron loss evaluation method by using the stator model core is shown by the simulation with FEM and the heat measurement with thermography camera.

  14. Friction Surface Treatment Selection: Aggregate Properties, Surface Characteristics, Alternative Treatments, and Safety Effects

    Science.gov (United States)

    2017-07-01

    This study aimed to evaluate the long term performance of the selected surface friction treatments, including high friction surface treatment (HFST) using calcined bauxite and steel slag, and conventional friction surfacing, in particular pavement pr...

  15. 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

  16. Evaluation of the viscoelastic behaviour and glass/mould interface friction coefficient in the wafer based precision glass moulding

    DEFF Research Database (Denmark)

    Sarhadi, Ali; Hattel, Jesper Henri; Hansen, Hans Nørgaard

    2014-01-01

    -placements, internal diameter and thickness of the rings are measured during the tests. Viscoelastic andstructural relaxation behaviour of the glass are implemented into the ABAQUS FEM software through aFORTRAN material subroutine (UMAT) and the FE model is validated with a sandwich seal test. Then, byFE simulation...... of the ring compression test and comparison of the experimental creep with the simulatedone in an iterative procedure, viscoelastic parameters of the glass material are characterized. Finally,interfacial glass/mould friction coefficients at different temperatures are determined through FEM basedfriction...... curves combined with experimental data points. The obtained viscoelastic parameters and inter-facial friction coefficients can later be employed for prediction of the final shape/size as well as the stressdistribution in the glass wafer during a real wafer based precision glass moulding process. © 2014...

  17. A Microstructural Evaluation of Friction Stir Welded 7075 Aluminum Rolled Plate Heat Treated to the Semi-Solid State

    Directory of Open Access Journals (Sweden)

    Ava Azadi Chegeni

    2018-01-01

    Full Text Available Two rolled plates of 7075 aluminum alloy were used as starting material. The plates were welded using a simultaneous double-sided friction stir welding (FSW process. One way of obtaining feedstock materials for Semi-solid processing or thixoforming is via deformation routes followed by partial melting in the semi-solid state. As both the base plate materials and the friction weld area have undergone extensive deformation specimens were subjected to a post welding heat-treatment in the semi-solid range at a temperature of 628 °C, for 3 min in order to observe the induced microstructural changes. A comparison between the microstructural evolution and mechanical properties of friction stir welded plates was performed before and after the heat-treatment in the Base Metal (BM, the Heat Affected Zone (HAZ, the Thermomechanically Affected Zone (TMAZ and the Nugget Zone (NZ using optical microscopy, Scanning Electron microscopy (SEM and Vickers hardness tests. The results revealed that an extremely fine-grained structure, obtained in the NZ after FSW, resulted in a rise of hardness from the BM to the NZ. Furthermore, post welding heat-treatment in the semi-solid state gave rise to a consistent morphology throughout the material which was similar to microstructures obtained by the thixoforming process. Moreover, a drop of hardness was observed after heat treatment in all regions as compared to that in the welded microstructure.

  18. 75 FR 30693 - Revised Medical Criteria for Evaluating Hearing Loss

    Science.gov (United States)

    2010-06-02

    ... pathways from the inner ear to the brain. Persons with the degree of sensorineural hearing loss required in... commenter recommended that we raise the average air conduction threshold in proposed listing 102.10A to... with an IQ of 35-55; the WHO's is similar, with an IQ of 35-49. In either case, the mental retardation...

  19. The Cross-Cultural Loss Scale: development and psychometric evaluation.

    Science.gov (United States)

    Wang, Kenneth T; Wei, Meifen; Zhao, Ran; Chuang, Chih-Chun; Li, Feihan

    2015-03-01

    The Cross-Cultural Loss Scale (CCLS), a measure of loss associated with crossing national boundaries, was developed across 2 samples of international students. With Sample 1 (N = 262), exploratory factor analyses were used to select the 14 CCLS items and to determine 3 factors: Belonging-Competency (α = .87), National Privileges (α = .68), and Access to Home Familiarity (α = .72). With Sample 2, confirmatory factor analyses (N = 256) cross-validated the 3-factor oblique model as well as a bifactor model. Cronbach alphas of CCLS subscale scores in Sample 2 ranged from .73 to .87. The validity of the CCLS scores was supported by its associations with related variables in the expected directions. Perceived cross-cultural losses were positively associated with negative affect, migration grief and loss, and discrimination and were negatively associated with life satisfaction, positive affect, general self-efficacy, and social connection with mainstream society. Moreover, the CCLS total and 2 subscale scores added significant incremental variance in predicting subjective well-being over and above related constructs. The results indicated measurement invariance and validity equivalency for the CCLS scores between men and women. The overall results from these 2 samples support CCLS as a psychometrically strong measure. 2015 APA, all rights reserved

  20. Targeted surveillance for postnatal hearing loss: a program evaluation.

    Science.gov (United States)

    Beswick, Rachael; Driscoll, Carlie; Kei, Joseph; Glennon, Shirley

    2012-07-01

    The importance of monitoring hearing throughout early childhood cannot be understated. However, there is a lack of evidence available regarding the most effective method of monitoring hearing following the newborn screen. The goal of this study was to describe a targeted surveillance program using a risk factor registry to identify children with a postnatal hearing loss. All children who were born in Queensland, Australia between September 2004 and December 2009, received a bilateral 'pass' on newborn hearing screening, and had at least one risk factor, were referred for targeted surveillance and were included in this study. The cohort was assessed throughout early childhood in accordance with Queensland's diagnostic assessment protocols. During the study period, 7320 (2.8% of 261,328) children were referred for targeted surveillance, of which 56 were identified with a postnatal hearing loss (0.77%). Of these, half (50.0%) were identified with a mild hearing loss, and 64.3% were identified with a sensorineural hearing loss. In regards to risk factors, syndrome, craniofacial anomalies, and severe asphyxia had the highest yield of positive cases of postnatal hearing loss for children referred for targeted surveillance, whereas, low birth weight, bacterial meningitis, and professional concern had a particularly low yield. Limitations of the targeted surveillance program were noted and include: (1) a lost contact rate of 32.4%; (2) delays in first surveillance assessment; (3) a large number of children who required on-going monitoring; and (4) extensive diagnostic assessments were completed on children with normal hearing. Examination of the lost contact rate revealed indigenous children were more likely to be documented as lost contact. In addition, children with one risk factor only were significantly more likely to not attend a surveillance appointment. Positive cases of postnatal hearing loss were detected through the targeted surveillance program. However, the

  1. Multi criteria evaluation for universal soil loss equation based on geographic information system

    Science.gov (United States)

    Purwaamijaya, I. M.

    2018-05-01

    The purpose of this research were to produce(l) a conceptual, functional model designed and implementation for universal soil loss equation (usle), (2) standard operational procedure for multi criteria evaluation of universal soil loss equation (usle) using geographic information system, (3) overlay land cover, slope, soil and rain fall layers to gain universal soil loss equation (usle) using multi criteria evaluation, (4) thematic map of universal soil loss equation (usle) in watershed, (5) attribute table of universal soil loss equation (usle) in watershed. Descriptive and formal correlation methods are used for this research. Cikapundung Watershed, Bandung, West Java, Indonesia was study location. This research was conducted on January 2016 to May 2016. A spatial analysis is used to superimposed land cover, slope, soil and rain layers become universal soil loss equation (usle). Multi criteria evaluation for universal soil loss equation (usle) using geographic information system could be used for conservation program.

  2. A molecular dynamics (MD simulation on tire-aggregate friction

    Directory of Open Access Journals (Sweden)

    Fengyan Sun

    2017-07-01

    Full Text Available The friction between tire and road surface is fundamentally depending on the molecular forces. In this paper, the nanoscale 3D contact model is employed to investigate the tire-aggregate friction mechanism. The tire and aggregate micro-structure are both constructed to evaluate the microscopic performance of tire-aggregate friction influence. Simulation results show for a high velocity, the energy dissipation of sliding on crystal structure is small, which results in a small friction coefficient; temperature will have influences on the friction coefficient, and with the increasing of velocity, the effect will gradually reduce. Keywords: Tire, Aggregate, Friction coefficient, Microscopic mechanism, MD simulation

  3. 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

  4. Loss of the CNA I secured river water system: analysis and effect evaluation

    International Nuclear Information System (INIS)

    Berra, Sandra; Guala, Mariana I.; Lorenzo, Andrea T.; Raffo Calderon, Maria C.; Urrutia, Guillermo

    1999-01-01

    In this work the evolution of the plant parameters is evaluated in the case of a loss of the secured circuit of river water (system UK). In particular the systems which are affected for this loss were studied. It was evaluated the functional degradation of these systems. (author)

  5. Friction measurement in a hip wear simulator.

    Science.gov (United States)

    Saikko, Vesa

    2016-05-01

    A torque measurement system was added to a widely used hip wear simulator, the biaxial rocking motion device. With the rotary transducer, the frictional torque about the drive axis of the biaxial rocking motion mechanism was measured. The principle of measuring the torque about the vertical axis above the prosthetic joint, used earlier in commercial biaxial rocking motion simulators, was shown to sense only a minor part of the total frictional torque. With the present method, the total frictional torque of the prosthetic hip was measured. This was shown to consist of the torques about the vertical axis above the joint and about the leaning axis. Femoral heads made from different materials were run against conventional and crosslinked polyethylene acetabular cups in serum lubrication. Regarding the femoral head material and the type of polyethylene, there were no categorical differences in frictional torque with the exception of zirconia heads, with which the lowest values were obtained. Diamond-like carbon coating of the CoCr femoral head did not reduce friction. The friction factor was found to always decrease with increasing load. High wear could increase the frictional torque by 75%. With the present system, friction can be continuously recorded during long wear tests, so the effect of wear on friction with different prosthetic hips can be evaluated. © IMechE 2016.

  6. Evaluation for Loss of Lubrication Performance of Black Oxide, Superfinished, and As-Ground Surfaces for Use in Rotorcraft Transmissions

    Science.gov (United States)

    2016-09-01

    9. SPONSORING/ MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S) 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 12...loss of lubrication. The ball-on-disc tribometer monitors the coefficient of friction within the contact, and scuffing initiation is indicated by a...corresponding set of as-ground balls. The ISF specimens had an Sa roughness value averaging to be 55 nm. A competitor process for improved surface

  7. Preparation of silver-cuprous oxide/stearic acid composite coating with superhydrophobicity on copper substrate and evaluation of its friction-reducing and anticorrosion abilities

    Energy Technology Data Exchange (ETDEWEB)

    Li, Peipei [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Kaifeng 475004 (China); Chen, Xinhua [College of Chemistry and Chemical Engineering, Xuchang University, Xuchang 461000 (China); Yang, Guangbin; Yu, Laigui [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Kaifeng 475004 (China); Zhang, Pingyu, E-mail: pingyu@henu.edu.cn [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Kaifeng 475004 (China)

    2014-01-15

    A simple two-step solution immersion process was combined with surface-modification by stearic acid to prepare superhydrophobic coatings on copper substrates so as to reduce friction coefficient, increase wear resistance and improve the anticorrosion ability of copper. Briefly, cuprous oxide (Cu{sub 2}O) crystal coating with uniform and compact tetrahedron structure was firstly created by immersing copper substrate in 2 mol L{sup −1} NaOH solution. As-obtained Cu{sub 2}O coating was then immersed in 0.33 mmol L{sup −1} AgNO{sub 3} solution to incorporate silver nanoparticles, followed by modification with stearic acid (denoted as SA) coating to achieve hydrophobicity. The surface morphology and chemical composition of silver-cuprous oxide/stearic acid (denoted as Ag-Cu{sub 2}O/SA) composite coating were investigated using a scanning electron microscope and an X-ray photoelectron spectroscope (XPS); and its phase structure was examined with an X-ray diffractometer (XRD). Moreover, the contact angle of water on as-prepared Ag-Cu{sub 2}O/SA composite coating was measured, and its friction-reducing and anticorrosion abilities were evaluated. It was found that as-prepared Ag-Cu{sub 2}O/SA composite coating has a water contact angle of as high as 152.4{sup o} and can provide effective friction-reducing, wear protection and anticorrosion protection for copper substrate, showing great potential for surface-modification of copper.

  8. Tribological Testing of Hemispherical Titanium Pin Lubricated by Novel Palm Oil: Evaluating Anti-Wear and Anti-Friction Properties

    Institute of Scientific and Technical Information of China (English)

    Norzahir Sapawe; Syahrullail Samion; Mohd Izhan Ibrahim; Md Razak Daud; Azli Yahya; Muhammad Farhan Hanafi

    2017-01-01

    In this study,the properties of hip implant material and lubricants were examined using a pin on disc apparatus,to compare the effect of metal-on-metal (MoM) contact with a bio-lubricant derived from palm oil.The behaviour of the lubricants was observed during the experiments,in which a hemispherical pin was loaded against a rotating disc with a groove.A titanium alloy was used to modify the hemispherical pin and disc.Before and after the experiments,the weight and surface roughness were analysed,to detect any degradation.The results were compared according to the different kinematic viscosities.The wear rates and level of friction with each lubricant were also examined.The lubricant with the highest viscosity had the lowest frictional value.Therefore,developing suitable lubricants has the potential to prolong the lifespan of prostheses or implants used in biomedical applications.The experiments collectively show that lubricants derived from palm oil could be used as efficient bio-lubricants in the future.

  9. Evaluation of Microstructure, Mechanical Properties and Corrosion Resistance of Friction Stir-Welded Aluminum and Magnesium Dissimilar Alloys

    Science.gov (United States)

    Verma, Jagesvar; Taiwade, Ravindra V.; Sapate, Sanjay G.; Patil, Awanikumar P.; Dhoble, Ashwinkumar S.

    2017-10-01

    Microstructure, mechanical properties and corrosion resistance of dissimilar friction stir-welded aluminum and magnesium alloys were investigated by applying three different rotational speeds at two different travel speeds. Sound joints were obtained in all the conditions. The microstructure was examined by an optical and scanning electron microscope, whereas localized chemical information was studied by energy-dispersive spectroscopy. Stir zone microstructure showed mixed bands of Al and Mg with coarse and fine equiaxed grains. Grain size of stir zone reduced compared to base metals, indicated by dynamic recrystallization. More Al patches were observed in the stir zone as rotational speed increased. X-ray diffraction showed the presence of intermetallics in the stir zone. Higher tensile strength and hardness were obtained at a high rotational speed corresponding to low travel speed. Tensile fractured surface indicated brittle nature of joints. Dissimilar friction stir weld joints showed different behaviors in different corrosive environments, and better corrosion resistance was observed at a high rotational speed corresponding to low travel speed (FW3) in a sulfuric and chloride environments. Increasing travel speed did not significantly affect on microstructure, mechanical properties and corrosion resistance as much as the rotational speed.

  10. Using a phosphorus loss model to evaluate and improve phosphorus indices.

    Science.gov (United States)

    Bolster, Carl H; Vadas, Peter A; Sharpley, Andrew N; Lory, John A

    2012-01-01

    In most states, the phosphorus (P) index (PI) is the adopted strategy for assessing a field's vulnerability to P loss; however, many state PIs have not been rigorously evaluated against measured P loss data to determine how well the PI assigns P loss risk-a major reason being the lack of field data available for such an analysis. Given the lack of P loss data available for PI evaluation, our goal was to demonstrate how a P loss model can be used to evaluate and revise a PI using the Pennsylvania (PA) PI as an example. Our first objective was to compare two different formulations-multiplicative and component-for calculating a PI. Our second objective was to evaluate whether output from a P loss model can be used to improve PI weighting by calculating weights for modified versions of the PA PI from model-generated P loss data. Our results indicate that several potential limitations exist with the original multiplicative index formulation and that a component formulation is more consistent with how P loss is calculated with P loss models and generally provides more accurate estimates of P loss. Moreover, using the PI weights calculated from the model-generated data noticeably improved the correlation between PI values and a large and diverse measured P loss data set. The approach we use here can be used with any P loss model and PI and thus can serve as a guide to assist states in evaluating and modifying their PI. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  11. EVALUATION OF NANOFILTRATION PRETREATMENTS FOR FLUX LOSS CONTROL

    Science.gov (United States)

    Differing nanofiltration pretreatment approaches for Ohio River water were evaluated withthe intent of producing systems with varying degrees of biological fouling. The membrane feed water was alum-coagulated, settled, and filtered Ohio River water (SF-ORW). Five 1.8" x 12" N...

  12. Inter-Institutional Comparison on Working Power Loss Evaluated Cases

    Directory of Open Access Journals (Sweden)

    Volkan Ünal

    2016-04-01

    Full Text Available Objective: In Turkey, individuals who want to retire due to illness and determined within the provisions of the relevant rules and regulations are defined as 'retirement due to disability1. When the insured apply with a petition, describing that s/he cannot work because of the diseases, retirement process begins. First Social Security Institution in case of objection Social Security Supreme Council of Health prepares reports about individuals. Third Specialization Board of the Council of Forensic Medicine is the final expertise authority on these cases. With this study it is aimed to reveal the decision differences on 'retirement due to disability1 cases between the Third Specialization Board of the Council of Forensic Medicine and the other institutions and, guided with the findings, to provide the standardization in practical implementation. Materials and Methods: For this study; the reports of the 3rd Specialization Board of The Council of Forensic Medicine were retrospectively investigated and the cases who were reported as not suitable for the retirement due to diseases by Social Security Institution and Social Security Supreme Council of Health but reported as suitable for the retirement due to diseases by the 3”1 Specialization Board were included. Results: Totally sixty four cases were determined. Fifty seven of the cases were male and seven ofthem were female. Average age of female cases was 50.71, male cases were 49.89 and average age of all cases was 49.98. Conclusion: Even the rules and regulations are same, there are differences between institutions. While rules and regulations are constituted, taking common decisions by negotiating on practice principles should reduce the differences between institutions and provide faster decision makings. Institutions should arrange routine meetings and discuss about the cases and present assessments interactively. Keywords: Working Power Loss, Inter-Instutional Comparison, Forensic medicine.

  13. Evaluation of Loss Due to Storm Surge Disasters in China Based on Econometric Model Groups

    Science.gov (United States)

    Shi, Xiaoxia; Xu, Tongbin; Yin, Kedong

    2018-01-01

    Storm surge has become an important factor restricting the economic and social development of China’s coastal regions. In order to improve the scientific judgment of future storm surge damage, a method of model groups is proposed to refine the evaluation of the loss due to storm surges. Due to the relative dispersion and poor regularity of the natural property data (login center air pressure, maximum wind speed, maximum storm water, super warning water level, etc.), storm surge disaster is divided based on eight kinds of storm surge disaster grade division methods combined with storm surge water, hypervigilance tide level, and disaster loss. The storm surge disaster loss measurement model groups consist of eight equations, and six major modules are constructed: storm surge disaster in agricultural loss, fishery loss, human resource loss, engineering facility loss, living facility loss, and direct economic loss. Finally, the support vector machine (SVM) model is used to evaluate the loss and the intra-sample prediction. It is indicated that the equations of the model groups can reflect in detail the relationship between the damage of storm surges and other related variables. Based on a comparison of the original value and the predicted value error, the model groups pass the test, providing scientific support and a decision basis for the early layout of disaster prevention and mitigation. PMID:29584628

  14. Evaluation of Loss Due to Storm Surge Disasters in China Based on Econometric Model Groups.

    Science.gov (United States)

    Jin, Xue; Shi, Xiaoxia; Gao, Jintian; Xu, Tongbin; Yin, Kedong

    2018-03-27

    Storm surge has become an important factor restricting the economic and social development of China's coastal regions. In order to improve the scientific judgment of future storm surge damage, a method of model groups is proposed to refine the evaluation of the loss due to storm surges. Due to the relative dispersion and poor regularity of the natural property data (login center air pressure, maximum wind speed, maximum storm water, super warning water level, etc.), storm surge disaster is divided based on eight kinds of storm surge disaster grade division methods combined with storm surge water, hypervigilance tide level, and disaster loss. The storm surge disaster loss measurement model groups consist of eight equations, and six major modules are constructed: storm surge disaster in agricultural loss, fishery loss, human resource loss, engineering facility loss, living facility loss, and direct economic loss. Finally, the support vector machine (SVM) model is used to evaluate the loss and the intra-sample prediction. It is indicated that the equations of the model groups can reflect in detail the relationship between the damage of storm surges and other related variables. Based on a comparison of the original value and the predicted value error, the model groups pass the test, providing scientific support and a decision basis for the early layout of disaster prevention and mitigation.

  15. Evaluation of Loss Due to Storm Surge Disasters in China Based on Econometric Model Groups

    Directory of Open Access Journals (Sweden)

    Xue Jin

    2018-03-01

    Full Text Available Storm surge has become an important factor restricting the economic and social development of China’s coastal regions. In order to improve the scientific judgment of future storm surge damage, a method of model groups is proposed to refine the evaluation of the loss due to storm surges. Due to the relative dispersion and poor regularity of the natural property data (login center air pressure, maximum wind speed, maximum storm water, super warning water level, etc., storm surge disaster is divided based on eight kinds of storm surge disaster grade division methods combined with storm surge water, hypervigilance tide level, and disaster loss. The storm surge disaster loss measurement model groups consist of eight equations, and six major modules are constructed: storm surge disaster in agricultural loss, fishery loss, human resource loss, engineering facility loss, living facility loss, and direct economic loss. Finally, the support vector machine (SVM model is used to evaluate the loss and the intra-sample prediction. It is indicated that the equations of the model groups can reflect in detail the relationship between the damage of storm surges and other related variables. Based on a comparison of the original value and the predicted value error, the model groups pass the test, providing scientific support and a decision basis for the early layout of disaster prevention and mitigation.

  16. Using a P loss model to evaluate and improve P indices

    Science.gov (United States)

    In most states, the phosphorus (P) index (PI) is the adopted strategy for assessing a field’s vulnerability to P loss when preparing comprehensive nutrient management plans. Most state PIs, however, have not been rigorously evaluated against measured P loss data to determine how well the PI assigns ...

  17. Use of infrared thermography for the evaluation of heat losses during coal storage

    NARCIS (Netherlands)

    Fierro, V.; Miranda, J.L.; Romero, C.; Andrés, J.M.; Pierrot, A.; Gómez-Landesa, E.; Arriaga, A.; Schmal, D.

    1999-01-01

    The exothermic processes during coal storage reduce the calorific value of the coal which in turn results in financial losses. An accurate and easy calculation of the losses may be an efficient tool to evaluate the effectiveness of the measures taken to reduce the spontaneous heating of coal and to

  18. Comparative Evaluation of Friction Resistance of Titanium, Stainless Steel, Ceramic and Ceramic with Metal Insert Brackets with Varying Dimensions of Stainless Steel Wire: An In vitro Multi-center Study.

    Science.gov (United States)

    Kumar, B Sunil; Miryala, Suresh; Kumar, K Kiran; Shameem, K; Regalla, Ravindra Reddy

    2014-09-01

    The orthodontist seeks an archwire-bracket combination that has both good biocompatibility and low friction. Hence, the aim of this multicenter in vitro study was to evaluate and compare the frictional resistance generated between titanium (Ti), stainless steel (SS), ceramic and ceramic with metal insert (CMI) brackets with SS wires of varying dimensions in a specially designed apparatus. The material used in this study were Ti, SS, Ceramic and CMI with 0.018″ slot manufactured with zero degree tip and -7° torque premolar brackets (3M, Unitek) and SS wires of varying dimensions (0.016″ round, 0.016 × 0.016″ square, 0.016 × 0.022″ rectangular and 0.017 × 0.025″ rectangular) used. The frictional resistance was measured using Instron Universal testing machine (Model no. 4301). The specimen population in each center composed each of 160 brackets and wires. Differences among the all bracket/wire combinations were tested using (one-way) ANOVA, followed by the student Newman Keuls multiple comparisons of means ranking (at P bracket in combination with 0.017 × 0.025″ SS rectangular wire produced significant force levels for an optimum orthodontic movement with least frictional resistance. Ti brackets have least resistance and rectangular wires produced significant force. These can be used to avoid hazards of Nickel. SS brackets revealed higher static frictional force values as the wire dimension increased and showed lower static friction than Ti brackets for all wires except the thicker wire. Our study recommends the preclusion of brackets with rough surface texture (Ti brackets) with SS ligature wire for ligating bracket and archwire are better to reduce friction.

  19. An Evaluation of Intra‑ and Post‑operative Blood Loss in Total Hip ...

    African Journals Online (AJOL)

    2017-05-18

    May 18, 2017 ... Results: The mean intra‑ and post‑operative blood losses were 1222.7 ... To evaluate blood loss after total hip replacement. 2. To evaluate the .... 12.3. 4.2. 0.1. Median. 400.0. 150.0. 20.0. 3.0. Mode. 400.0. 100.0. 0.0. 3.0. SD.

  20. Initial assessment of hearing loss using a mobile application for audiological evaluation.

    Science.gov (United States)

    Derin, S; Cam, O H; Beydilli, H; Acar, E; Elicora, S S; Sahan, M

    2016-03-01

    This study aimed to compare an Apple iOS mobile operating system application for audiological evaluation with conventional audiometry, and to determine its accuracy and reliability in the initial evaluation of hearing loss. The study comprised 32 patients (16 females) diagnosed with hearing loss. The patients were first evaluated with conventional audiometry and the degree of hearing loss was recorded. Then they underwent a smartphone-based hearing test and the data were compared using Cohen's kappa analysis. Patients' mean age was 53.59 ± 18.01 years (range, 19-85 years). The mobile phone audiometry results for 39 of the 64 ears were fully compatible with the conventional audiometry results. There was a statistically significant concordant relationship between the two sets of audiometry results (p Apple iPhone 5 that can measure hearing loss with reliable results.

  1. FRICTION-BOON OR BANE IN ORTHODONTICS

    Directory of Open Access Journals (Sweden)

    Sameer

    2015-11-01

    Full Text Available OBJECTIVE: Most fixed appliance techniques involve some degree of sliding between brackets and arch wires. A sound knowledge of the various factors affecting the magnitude of friction is of paramount importance to the clinician. The present study was performed to evaluate and compare the frictional resistance and characteristics between self-ligating brackets and pre-adjusted edgewise brackets with different types of ligation. MATERIALS AND METHODS: Tidy's frictional test design was used to simulate retraction of tooth along with artificial saliva to simulate wet conditions in oral cavity. The jig with this assembly was mounted on the Instron machine with the cross head moving upwards at a speed of 5mm/min. The movable bracket was suspended from the load cell of the testing machine, while the jig was mounted on cross head of machine and the load cell readings were recorded on digital display. Following wires are used 0.016 HANT, 0.019X 0.025HANT, 0.019X 0.025 SS, 0.021X 0.025 SS wires are used. The brackets used were 0.022 slot Damon, 0.022 Smart clip and 0.022 slot MBT system. RESULTS: Self ligating brackets were shown to produce lesser friction when compared to the conventional brackets used with modules, and stainless steel ligatures. Damon self-ligating brackets produce a least friction of all the brackets used in the study. Stainless steel ligatures produced the least friction compared to elastomeric. CONCLUSION: Self ligation brackets produce lesser friction than the conventional brackets ligated with elastomeric modules and stainless steel ligature. Damon self-ligating brackets produce a least friction of all the brackets used in the study width of the bracket was also found to be directly proportional to the friction produced 0.0016HANT with elastomeric modules produce more friction due increase in flexibility of wire.

  2. A High Precision Comprehensive Evaluation Method for Flood Disaster Loss Based on Improved Genetic Programming

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yuliang; LU Guihua; JIN Juliang; TONG Fang; ZHOU Ping

    2006-01-01

    Precise comprehensive evaluation of flood disaster loss is significant for the prevention and mitigation of flood disasters. Here, one of the difficulties involved is how to establish a model capable of describing the complex relation between the input and output data of the system of flood disaster loss. Genetic programming (GP) solves problems by using ideas from genetic algorithm and generates computer programs automatically. In this study a new method named the evaluation of the grade of flood disaster loss (EGFD) on the basis of improved genetic programming (IGP) is presented (IGPEGFD). The flood disaster area and the direct economic loss are taken as the evaluation indexes of flood disaster loss. Obviously that the larger the evaluation index value, the larger the corresponding value of the grade of flood disaster loss is. Consequently the IGP code is designed to make the value of the grade of flood disaster be an increasing function of the index value. The result of the application of the IGP-EGFD model to Henan Province shows that a good function expression can be obtained within a bigger searched function space; and the model is of high precision and considerable practical significance.Thus, IGP-EGFD can be widely used in automatic modeling and other evaluation systems.

  3. 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.)

  4. Amino Acid Signatures to Evaluate the Beneficial Effects of Weight Loss

    Directory of Open Access Journals (Sweden)

    Nina Geidenstam

    2017-01-01

    Full Text Available Aims. We investigated the relationship between circulating amino acid levels and obesity; to what extent weight loss followed by weight maintenance can correct amino acid abnormalities; and whether amino acids are related to weight loss. Methods. Amino acids associated with waist circumference (WC and BMI were studied in 804 participants from the Malmö Diet and Cancer Cardiovascular Cohort (MDC-CC. Changes in amino acid levels were analyzed after weight loss and weight maintenance in 12 obese subjects and evaluated in a replication cohort (n=83. Results. Out of the eight identified BMI-associated amino acids from the MDC-CC, alanine, isoleucine, tyrosine, phenylalanine, and glutamate decreased after weight loss, while asparagine increased after weight maintenance. These changes were validated in the replication cohort. Scores that were constructed based on obesity-associated amino acids and known risk factors decreased in the ≥10% weight loss group with an associated change in BMI (R2=0.16–0.22, p<0.002, whereas the scores increased in the <10% weight loss group (p<0.0004. Conclusions. Weight loss followed by weight maintenance leads to differential changes in amino acid levels associated with obesity. Treatment modifiable scores based on epidemiological and interventional data may be used to evaluate the potential metabolic benefit of weight loss.

  5. Use of Annual Phosphorus Loss Estimator (APLE) Model to Evaluate a Phosphorus Index.

    Science.gov (United States)

    Fiorellino, Nicole M; McGrath, Joshua M; Vadas, Peter A; Bolster, Carl H; Coale, Frank J

    2017-11-01

    The Phosphorus (P) Index was developed to provide a relative ranking of agricultural fields according to their potential for P loss to surface water. Recent efforts have focused on updating and evaluating P Indices against measured or modeled P loss data to ensure agreement in magnitude and direction. Following a recently published method, we modified the Maryland P Site Index (MD-PSI) from a multiplicative to a component index structure and evaluated the MD-PSI outputs against P loss data estimated by the Annual P Loss Estimator (APLE) model, a validated, field-scale, annual P loss model. We created a theoretical dataset of fields to represent Maryland conditions and scenarios and created an empirical dataset of soil samples and management characteristics from across the state. Through the evaluation process, we modified a number of variables within the MD-PSI and calculated weighting coefficients for each P loss component. We have demonstrated that our methods can be used to modify a P Index and increase correlation between P Index output and modeled P loss data. The methods presented here can be easily applied in other states where there is motivation to update an existing P Index. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  6. NASA tire/runway friction projects

    Science.gov (United States)

    Yager, Thomas J.

    1995-01-01

    The paper reviews several aspects of NASA Langley Research Center's tire/runway friction evaluations directed towards improving the safety and economy of aircraft ground operations. The facilities and test equipment used in implementing different aircraft tire friction studies and other related aircraft ground performance investigations are described together with recent workshop activities at NASA Wallops Flight Facility. An overview of the pending Joint NASA/Transport Canada/FM Winter Runway Friction Program is given. Other NASA ongoing studies and on-site field tests are discussed including tire wear performance and new surface treatments. The paper concludes with a description of future research plans.

  7. Nonlinear friction dynamics on polymer surface under accelerated movement

    Directory of Open Access Journals (Sweden)

    Yuuki Aita

    2017-04-01

    Full Text Available Nonlinear phenomena on the soft material surface are one of the most exciting topics of chemical physics. However, only a few reports exist on the friction phenomena under accelerated movement, because friction between two solid surfaces is considered a linear phenomenon in many cases. We aim to investigate how nonlinear accelerated motion affects friction on solid surfaces. In the present study, we evaluate the frictional forces between two polytetrafluoroethylene (PTFE resins using an advanced friction evaluation system. On PTFE surfaces, the normalized delay time δ, which is the time lag in the response of the friction force to the accelerated movement, is observed in the pre-sliding friction process. Under high-velocity conditions, kinetic friction increases with velocity. Based on these experimental results, we propose a two-phase nonlinear model including a pre-sliding process (from the beginning of sliding of a contact probe to the establishment of static friction and a kinetic friction process. The present model consists of several factors including velocity, acceleration, stiffness, viscosity, and vertical force. The findings reflecting the viscoelastic properties of soft material is useful for various fields such as in the fabrication of clothes, cosmetics, automotive materials, and virtual reality systems as well as for understanding friction phenomena on soft material surfaces.

  8. Economic evaluation of health losses from air pollution in Beijing, China.

    Science.gov (United States)

    Zhao, Xiaoli; Yu, Xueying; Wang, Ying; Fan, Chunyang

    2016-06-01

    Aggravated air pollution in Beijing, China has caused serious health concern. This paper comprehensively evaluates the health losses from illness and premature death caused by air pollution in monetary terms. We use the concentration of PM10 as an indicator of the pollution since it constitutes the primary pollutant in Beijing. By our estimation, air pollution in Beijing caused a health loss equivalent to Ұ583.02 million or 0.03 % of its GDP. Most of the losses took the form of depreciation in human capital that resulted from premature death. The losses from premature deaths were most salient for people of either old or young ages, with the former group suffering from the highest mortality rates and the latter group the highest per capital losses of human capitals from premature death. Policies that target on PM10 emission reduction, urban vegetation expansion, and protection of vulnerable groups are all proposed as possible solutions to air pollution risks in Beijing.

  9. Evaluation of EEG based determination of unconsciousness vs. loss of posture in broilers.

    Science.gov (United States)

    Benson, E R; Alphin, R L; Rankin, M K; Caputo, M P; Kinney, C A; Johnson, A L

    2012-10-01

    Evaluation of the loss of consciousness in poultry is an essential component in evaluating bird welfare under a variety of situations and applications. Many current approaches to evaluating loss of consciousness are qualitative and require observation of the bird. This study outlines a quantitative method for determining the point at which a bird loses consciousness. In this study, commercial broilers were individually anesthetized and the brain activity recorded as the bird became unconscious. A wireless EEG transmitter was surgically implanted and the bird anesthetized after a 24-48 h recovery. Each bird was monitored during treatment with isoflurane anesthesia and EEG data was evaluated using a frequency based approach. The alpha/delta (A/D) ratio and loss of posture (LOP) were used to determine the point at which the birds went unconscious. There was no statistically significant difference between time to unconsciousness as measured by A/D ratio or LOP. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Development of a penetration friction apparatus (PFA) to measure the frictional performance of surgical suture.

    Science.gov (United States)

    Zhang, Gangqiang; Ren, Tianhui; Lette, Walter; Zeng, Xiangqiong; van der Heide, Emile

    2017-10-01

    Nowadays there is a wide variety of surgical sutures available in the market. Surgical sutures have different sizes, structures, materials and coatings, whereas they are being used for various surgeries. The frictional performances of surgical sutures have been found to play a vital role in their functionality. The high friction force of surgical sutures in the suturing process may cause inflammation and pain to the person, leading to a longer recovery time, and the second trauma of soft or fragile tissue. Thus, the investigation into the frictional performance of surgical suture is essential. Despite the unquestionable fact, little is actually known on the friction performances of surgical suture-tissue due to the lack of appropriate test equipment. This study presents a new penetration friction apparatus (PFA) that allowed for the evaluation of the friction performances of various surgical needles and sutures during the suturing process, under different contact conditions. It considered the deformation of tissue and can realize the puncture force measurements of surgical needles as well as the friction force of surgical sutures. The developed PFA could accurately evaluate and understand the frictional behaviour of surgical suture-tissue in the simulating clinical conditions. The forces measured by the PFA showed the same trend as that reported in literatures. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. [Evaluation of hearing loss parameters in workers and its relationship with fasting blood glucose levels].

    Science.gov (United States)

    Vicente-Herrero, M Teofila; Lladosa Marco, Silvia; Ramírez-Iñiguez de La Torre, M Victoria; Terradillos-García, M Jesús; López-González, Ángel Arturo

    2014-05-01

    Hearing loss due to noise is considered within the prevention plans of the most common occupational diseases. In addition to evaluation of working conditions, other personal factors increasing the risk of hypoacusis, such as diabetes, should be taken into account. To explore hearing loss in the workplace and its relationship to impaired fasting baseline blood glucose levels. An observational, cross-sectional study enrolling 1636 workers from service companies was conducted. Full audiometric evaluation was performed at different frequencies: high frequency (HF), early loss index (ELI), speech average loss (SAL), and monaural and binaural loss. Results were categorized by baseline blood glucose levels: G1 (125mg/dl). Based on both HF and ELI, 11% of workers had clear indication of deafness. Women with G3 levels showed significant differences in the results of HF and ELI indexes as compared to the G1 group (P=.038 and .046, respectively). A positive association was found between hearing loss and G3 blood glucose levels in HF (OR: .338; p=.002), ELI (OR: .407; p=.007), and the monaural test in the left ear (OR: 4.77×10-5; p=.006). Despite the methodological limitations of this study, there is evidence for an increased risk of high frequency hearing loss in workers with high baseline blood glucose levels. Copyright © 2013 SEEN. Published by Elsevier Espana. All rights reserved.

  12. LOW-ENGINE-FRICTION TECHNOLOGY FOR ADVANCED NATURAL-GAS RECIPROCATING ENGINES

    Energy Technology Data Exchange (ETDEWEB)

    Victor W. Wong; Tian Tian; Grant Smedley; Jeffrey Jocsak

    2004-09-30

    This program aims at improving the efficiency of advanced natural-gas reciprocating engines (ANGRE) by reducing piston/ring assembly friction without major adverse effects on engine performance, such as increased oil consumption and emissions. An iterative process of simulation, experimentation and analysis, are being followed towards achieving the goal of demonstrating a complete optimized low-friction engine system. To date, a detailed set of piston/ring dynamic and friction models have been developed and applied that illustrated the fundamental relationships between design parameters and friction losses. Various low-friction strategies and ring-design concepts have been explored, and engine experiments have been done on a full-scale Waukesha VGF F18 in-line 6 cylinder power generation engine rated at 370 kW at 1800 rpm. Current accomplishments include designing and testing ring-packs using a subtle top-compression-ring profile (skewed barrel design), lowering the tension of the oil-control ring, employing a negative twist to the scraper ring to control oil consumption. Initial test data indicate that piston ring-pack friction was reduced by 35% by lowering the oil-control ring tension alone, which corresponds to a 1.5% improvement in fuel efficiency. Although small in magnitude, this improvement represents a first step towards anticipated aggregate improvements from other strategies. Other ring-pack design strategies to lower friction have been identified, including reduced axial distance between the top two rings, tilted top-ring groove. Some of these configurations have been tested and some await further evaluation. Colorado State University performed the tests and Waukesha Engine Dresser, Inc. provided technical support. Key elements of the continuing work include optimizing the engine piston design, application of surface and material developments in conjunction with improved lubricant properties, system modeling and analysis, and continued technology

  13. Reduction of Noise from Disc Brake Systems Using Composite Friction Materials Containing Thermoplastic Elastomers (TPEs)

    Science.gov (United States)

    Masoomi, Mohsen; Katbab, Ali Asghar; Nazockdast, Hossein

    2006-09-01

    Attempts have been made for the first time to prepare a friction material with the characteristic of thermal sensitive modulus, by the inclusion of thermoplastic elastomers (TPE) as viscoelastic polymeric materials into the formulation in order to the increase the damping behavior of the cured friction material. Styrene butadiene styrene (SBS), styrene ethylene butylene styrene (SEBS) and nitrile rubber/polyvinyl chloride (NBR/PVC) blend system were used as TPE materials. In order to evaluate the viscoelastic parameters such as loss factor (tan δ) and storage modulus (E‧) for the friction material, dynamic mechanical analyzer (DMA) were used. Natural frequencies and mode shapes of friction material and brake disc were determined by modal analysis. However, NBR/PVC and SEBS were found to be much more effective in damping behavior. The results from this comparative study suggest that the damping characteristics of commercial friction materials can be strongly affected by the TPE ingredients. This investigation also confirmed that the specimens with high TPE content had low noise propensity.

  14. Adaptive Neuro-Fuzzy Computing Technique for Determining Turbulent Flow Friction Coefficient

    Directory of Open Access Journals (Sweden)

    Mohammad Givehchi

    2013-08-01

    Full Text Available Estimation of the friction coefficient in pipes is very important in many water and wastewater engineering issues, such as distribution of velocity and shear stress, erosion, sediment transport and head loss. In analyzing these problems, knowing the friction coefficient, can obtain estimates that are more accurate. In this study in order to estimate the friction coefficient in pipes, using adaptive neuro-fuzzy inference systems (ANFIS, grid partition method was used. For training and testing of neuro-fuzzy model, the data derived from the Colebrook’s equation was used. In the neuro-fuzzy approach, pipe relative roughness and Reynolds number are considered as input variables and friction coefficient as output variable is considered. Performance of the proposed approach was evaluated by using of the data obtained from the Colebrook’s equation and based on statistical indicators such as coefficient determination (R2, root mean squared error (RMSE and mean absolute error (MAE. The results showed that the adaptive nerou-fuzzy inference system with grid partition method and gauss model as an input membership function and linear as an output function could estimate friction coefficient more accurately than other conditions. The new proposed approach in this paper has capability of application in the practical design issues and can be combined with mathematical and numerical models of sediment transfer or real-time updating of these models.

  15. Evaluation of Iron Loss in Interior Permanent Magnet Synchronous Motor with Consideration of Rotational Field

    Science.gov (United States)

    Ma, Lei; Sanada, Masayuki; Morimoto, Shigeo; Takeda, Yoji; Kaido, Chikara; Wakisaka, Takeaki

    Loss evaluation is an important issue in the design of electrical machines. Due to the complicate structure and flux distribution, it is difficult to predict the iron loss in the machines exactly. This paper studies the iron loss in interior permanent magnet synchronous motors based on the finite element method. The iron loss test data of core material are used in the fitting of the hysteresis and eddy current loss constants. For motors in practical operation, additional iron losses due to the appearance of rotation of flux density vector and harmonic flux density distribution makes the calculation data deviates from the measured ones. Revision is made to account for these excess iron losses which exist in the practical operating condition. Calculation results show good consistence with the experimental ones. The proposed method provides a possible way to predict the iron loss of the electrical machine with good precision, and may be helpful in the selection of the core material which is best suitable for a certain machine.

  16. Evaluation of external heat loss from a small-scale expander used in organic Rankine cycle

    International Nuclear Information System (INIS)

    Li Jing; Pei Gang; Li Yunzhu; Ji Jie

    2011-01-01

    With the scaling down of the Organic Rankine Cycle (ORC), the engine shaft power is not only determined by the enthalpy drop in the expansion process but also the external heat loss from the expander. Theoretical and experimental support in evaluating small-scale expander heat loss is rare. This paper presents a quantitative study on the convection, radiation, and conduction heat transfer from a kW-scale expander. A mathematical model is built and validated. The results show that the external radiative or convective heat loss coefficient was about 3.2 or 7.0 W/K.m 2 when the ORC operated around 100 o C. Radiative and convective heat loss coefficients increased as the expander operation temperature increased. Conductive heat loss due to the connection between the expander and the support accounted for a large proportion of the total heat loss. The fitting relationships between heat loss and mean temperature difference were established. It is suggested that low conductivity material be embodied in the support of expander. Mattress insulation for compact expander could be eliminated when the operation temperature is around 100 o C. - Highlights: → A close examination of external heat loss from a small expander is presented. → Theoretical analysis and experimental test were conducted. → The established formulas can be applied to other small ORC expanders. → The results are useful in further research of small-scale ORC.

  17. Political frictions and public policy outcomes

    OpenAIRE

    Grechyna, Daryna

    2016-01-01

    We study the role of political frictions in public policy outcomes. We propose a simple model of fiscal policy that combines a lack of commitment by the government, political turnover, and another political friction that can be interpreted either as political polarization or as public rent-seeking. We show that political turnover increases public debt levels, while political polarization or public rent-seeking leads to higher public spending. We evaluate the importance of different political ...

  18. Quantum lubrication: Suppression of friction in a first-principles four-stroke heat engine

    Science.gov (United States)

    Feldmann, Tova; Kosloff, Ronnie

    2006-02-01

    A quantum model of a heat engine resembling the Otto cycle is employed to explore strategies to suppress frictional losses. These losses are caused by the inability of the engine’s working medium to follow adiabatically the change in the Hamiltonian during the expansion and compression stages. By adding external noise to the engine frictional losses can be suppressed.

  19. Friction characteristics of hardfacing materials in high temperature sodium

    International Nuclear Information System (INIS)

    Mizobuchi, Syotaro; Kano, Shigeki; Nakayama, Kohichi; Atsumo, Hideo

    1980-01-01

    Friction and self-welding test were conducted on several materials used for the contacting and sliding components of a sodium cooled fast breeder reactor. In the present study, the friction and self-welding characteristics of each material were evaluated through measuring the kinetic and breakaway friction coefficients. The influence of oscillating rotation and vertical reciprocating motion on the friction mode was also investigated. The results obtained are as follows: (1) Colmonoy No.6, the nickel base hardfacing alloy, indicated the lowest kinetic friction coefficient of all the materials in the present study. Also, Cr 3 C 2 /Ni-Cr material prepared by a detonation gun showed the most stable friction behavior. (2) The breakaway friction coefficient of each material was dependent upon dwelling time in a sodium environment. (3) The friction behavior of Cr 3 C 2 /Ni-Cr material was obviously related with the finishing roughness of the friction surface. It was anticipated that nichrome material as the binder of the chrome carbide diffused and exuded to the friction surface by sliding in sodium. (4) The friction coefficient in sliding mode of vertical reciprocating was lower than that of oscillating rotation. (author)

  20. An improved cost-effective, reproducible method for evaluation of bone loss in a rodent model.

    Science.gov (United States)

    Fine, Daniel H; Schreiner, Helen; Nasri-Heir, Cibele; Greenberg, Barbara; Jiang, Shuying; Markowitz, Kenneth; Furgang, David

    2009-02-01

    This study was designed to investigate the utility of two "new" definitions for assessment of bone loss in a rodent model of periodontitis. Eighteen rats were divided into three groups. Group 1 was infected by Aggregatibacter actinomycetemcomitans (Aa), group 2 was infected with an Aa leukotoxin knock-out, and group 3 received no Aa (controls). Microbial sampling and antibody titres were determined. Initially, two examiners measured the distance from the cemento-enamel-junction to alveolar bone crest using the three following methods; (1) total area of bone loss by radiograph, (2) linear bone loss by radiograph, (3) a direct visual measurement (DVM) of horizontal bone loss. Two "new" definitions were adopted; (1) any site in infected animals showing bone loss >2 standard deviations above the mean seen at that site in control animals was recorded as bone loss, (2) any animal with two or more sites in any quadrant affected by bone loss was considered as diseased. Using the "new" definitions both evaluators independently found that infected animals had significantly more disease than controls (DVM system; p<0.05). The DVM method provides a simple, cost effective, and reproducible method for studying periodontal disease in rodents.

  1. Iron losses evaluation in soft magnetic materials with a sinusoidal voltage supply

    DEFF Research Database (Denmark)

    Nedelcu, Steluţa; Ritchie, Ewen; Leban, Krisztina Monika

    2013-01-01

    This paper presents an evaluation method of for specific iron losses in non-oriented laminated steel suitable for electric motors and transformers in the case of a sinusoidal excitation. The model is based on the separation of loss contribution due to hysteresis, eddy currents and excess losses...... (between 0.35 mm and 0.65 mm) and alloy compositions. Hysteresis and eddy currents loss coefficients have been considered as dependent on the frequency. For curve fitting of these coefficients third and fourth polynomials were employed, with good result for all the frequencies and magnetic flux density...... and it is proposing an identification procedure for the model coefficients from multi-frequency single sheet tests. The frequencies used are in the range 10 Hz and 150 Hz and with the values of magnetic flux density in the range 0.1 T and 1.4 T. The model was applied on six magnetic materials of different thicknesses...

  2. Evaluation of internet websites marketing herbal weight-loss supplements to consumers.

    Science.gov (United States)

    Jordan, Melanie A; Haywood, Tasha

    2007-11-01

    The aim of this study was to evaluate the quality and quantity of drug information available to consumers on Internet websites marketing herbal weight-loss dietary supplements in the United States. We conducted an Internet search using the search engines Yahoo and Google and the keywords "herbal weight loss." Website content was evaluated for the presence of active/inactive ingredient names and strengths and other Food and Drug Administration (FDA) labeling requirements. Information related to drug safety for the most common herbal ingredients in the products evaluated was compared against standard herbal drug information references. Thirty-two (32) websites were evaluated for labeling requirements and safety information. All sites listed an FDA disclaimer statement and most sites (84.4%) listed active ingredients, although few listed strengths or inactive ingredients. Based on the drug information for the most common ingredients found in the weight-loss dietary supplements evaluated, potential contraindications for cardiovascular conditions, pregnancy/nursing, and high blood pressure were listed most frequently (73%, 65.5%, and 37%, respectively), whereas few websites listed potential drug interactions or adverse reactions. Potential hazards posed by dietary supplements may not be accurately, if at all, represented on Internet websites selling these products. Since consumers may not approach their physicians or pharmacists for information regarding use of dietary supplements in weight loss, it becomes necessary for health care providers to actively engage their patients in open discussion regarding the use, benefits, and hazards of dietary supplements.

  3. Evaluation of warm mix technologies for use in asphalt rubber - asphaltic concrete friction courses (AR\\0x2010ACFC) : final report.

    Science.gov (United States)

    2016-07-01

    The objective of this research project was to determine whether warm mix asphalt (WMA) technologies can be : used by the Arizona Department of Transportation (ADOT) for the production of an asphalt rubberasphaltic : concrete friction course (AR...

  4. 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....

  5. Evaluating the influential priority of the factors on insurance loss of public transit

    Science.gov (United States)

    Su, Yongmin; Chen, Xinqiang

    2018-01-01

    Understanding correlation between influential factors and insurance losses is beneficial for insurers to accurately price and modify the bonus-malus system. Although there have been a certain number of achievements in insurance losses and claims modeling, limited efforts focus on exploring the relative role of accidents characteristics in insurance losses. The primary objective of this study is to evaluate the influential priority of transit accidents attributes, such as the time, location and type of accidents. Based on the dataset from Washington State Transit Insurance Pool (WSTIP) in USA, we implement several key algorithms to achieve the objectives. First, K-means algorithm contributes to cluster the insurance loss data into 6 intervals; second, Grey Relational Analysis (GCA) model is applied to calculate grey relational grades of the influential factors in each interval; in addition, we implement Naive Bayes model to compute the posterior probability of factors values falling in each interval. The results show that the time, location and type of accidents significantly influence the insurance loss in the first five intervals, but their grey relational grades show no significantly difference. In the last interval which represents the highest insurance loss, the grey relational grade of the time is significant higher than that of the location and type of accidents. For each value of the time and location, the insurance loss most likely falls in the first and second intervals which refers to the lower loss. However, for accidents between buses and non-motorized road users, the probability of insurance loss falling in the interval 6 tends to be highest. PMID:29298337

  6. Evaluation of a cryostable low-loss conductor for pulsed field applications

    International Nuclear Information System (INIS)

    Wollan, J.J.; Walker, M.S.; Zeitlin, B.A.; Pollack, D.A.; Shen, S.S.

    1980-01-01

    A cryostable, low loss conductor as the basic strand in a 50 kA cable for a 20 MJ prototype, tokamak induction heating coil has been developed, fabricated, and evaluated. The conductor has a copper matrix multifilamentary NbTi core surrounded by a CuNi ring and stabilizing copper segmented by radial CuNi fins. Pulsed loss measurements have been made up to 2.2 T and for decay times from 0.7 to 278 ms. Measurements made on samples with various twists and portions etched away have allowed accurate evaluation of the loss components. Stability measurements were also made on insulated and uninsulated single strands and on subcables. Measured recovery heat flux for the bare strand is about 0.3 W/cm 2 ; however, the application of a 0.0005 in. layer of Omega insulation increases the value to about 0.5 W/cm 2

  7. Science 101: What Causes Friction?

    Science.gov (United States)

    Robertson, Bill

    2014-01-01

    Defining friction and asking what causes it might seem like a trivial question. Friction seems simple enough to understand. Friction is a force between surfaces that pushes against things that are moving or tending to move, and the rougher the surfaces, the greater the friction. Bill Robertson answers this by saying, "Well, not exactly".…

  8. Effect of time derivative of contact area on dynamic friction

    OpenAIRE

    Arakawa, Kazuo

    2015-01-01

    This study investigated dynamic friction during oblique impact of a golf ball by evaluating the ball’s angular velocity, contact force, and the contact area between the ball and target. The effect of the contact area on the angular velocities was evaluated, and the results indicated that the contact area plays an important role in dynamic friction. In this study, the dynamic friction force F was given by F= μN+μη.dA/dt, where μ is the coefficient of friction, N is the contact force, dA/dt is ...

  9. Evaluating the Amount of Tooth Movement and Root Resorption during Canine Retraction with Friction versus Frictionless Mechanics Using Cone Beam Computed Tomography.

    Science.gov (United States)

    Makhlouf, Mohamed; Aboul-Ezz, Amr; Fayed, Mona Salah; Hafez, Hend

    2018-02-15

    The current study was carried out to compare the amount of tooth movement during canine retraction comparing two different retraction mechanics; friction mechanics represented by a NiTi closed coil spring versus frictionless mechanics represented by T - loop, and their effect on root resorption using Cone Beam Computed Tomography (CBCT). Ten patients were selected in a split-mouth study design that had a malocclusion that necessitates the extraction of maxillary first premolars and retraction of maxillary canines. The right maxillary canines were retracted using T - loops fabricated from 0.017 X 0.025 TMA wires. The left maxillary canines received NiTi coil spring with 150 gm of retraction force. Pre retraction and post retraction Cone Beam Computed Tomography were taken to evaluate the amount of tooth movement and root resorption using three-dimensional planes. T - loop side showed statistically significant higher mean anteroposterior measurement than NiTi coil spring side, indicating a lower amount of canine movement pre and post a canine retraction. Concerning the root resorption, there was no statistically significant change in the mean measurements of canine root length post retraction. The NiTi coil spring side showed more distal movement more than the T-loop side. Both retraction mechanics with controlled retraction force, do not cause root resorption.

  10. Evaluating alternative fuel treatment strategies to reduce wildfire losses in a Mediterranean area

    Science.gov (United States)

    Michele Salis; Maurizio Laconi; Alan A. Ager; Fermin J. Alcasena; Bachisio Arca; Olga Lozano; Ana Fernandes de Oliveira; Donatella Spano

    2016-01-01

    The goal of this work is to evaluate by a modeling approach the effectiveness of alternative fuel treatment strategies to reduce potential losses from wildfires in Mediterranean areas. We compared strategic fuel treatments located near specific human values vs random locations, and treated 3, 9 and 15% of a 68,000 ha study area located in Sardinia, Italy. The...

  11. Hydrologic Impacts of Oak Harvesting and Evaluation of the Modified Universal Soil Loss Equation

    Science.gov (United States)

    Charlette R. Epifanio; Michael J. Singer; Xiaohong Huang

    1991-01-01

    Two Sierra foothill watersheds were monitored to learn what effects selective oak removal would have on watershed hydrology and water quality. We also used the data to generate sediment rating curves and evaluate the modified universal soil loss equation (MUSLE). Annual sediment rating curves better accounted for the variability in precipitation events from year to...

  12. MOSFET Loss Evaluation for a Low-Power Stand-Alone Photovoltaic-LED System

    DEFF Research Database (Denmark)

    Mira Albert, Maria del Carmen; Knott, Arnold; Andersen, Michael A. E.

    2015-01-01

    This paper presents a performance evaluation and comparison of state-of-the-art low voltage Si MOSFETs for a stand-alone photovoltaic-LED Light to Light (LtL) system. The complete system is formed by two cascaded converters that will be optimized for a determined solar irradiation and LED...... illumination profiles. The comparison is performed based on dynamic characterization and evaluation of the devices energy loss at different current levels....

  13. 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.

  14. 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.

  15. Evaluation of the dental structure loss produced during maintenance and replacement of occlusal amalgam restorations

    Directory of Open Access Journals (Sweden)

    Fernanda Sardenberg

    2008-09-01

    Full Text Available The aim of this in vitro study was to evaluate four different approaches to the decision of changing or not defective amalgam restorations in first primary molar teeth concerning the loss of dental structure. Ditched amalgam restorations (n = 11 were submitted to four different treatments, as follows: Control group - polishing and finishing of the restorations were carried out; Amalgam group - the ditched amalgam restorations were replaced by new amalgam restorations; Composite resin group - the initial amalgam restorations were replaced by composite resin restorations; Flowable resin group - the ditching around the amalgam restorations was filled with flowable resin. Images of the sectioned teeth were made and the area of the cavities before and after the procedures was determined by image analysis software to assess structural loss. The data were submitted to ANOVA complemented by the Student Newman Keuls test (p < 0.05. The cavities in all the groups presented significantly greater areas after the procedures. However, the amalgam group showed more substantial dental loss. The other three groups presented no statistically significant difference in dental structure loss after the re-treatments. Thus, replacing ditched amalgam restorations by other similar restorations resulted in a significant dental structure loss while maintaining them or replacing them by resin restorations did not result in significant loss.

  16. Evaluation of Structural Robustness against Column Loss: Methodology and Application to RC Frame Buildings.

    Science.gov (United States)

    Bao, Yihai; Main, Joseph A; Noh, Sam-Young

    2017-08-01

    A computational methodology is presented for evaluating structural robustness against column loss. The methodology is illustrated through application to reinforced concrete (RC) frame buildings, using a reduced-order modeling approach for three-dimensional RC framing systems that includes the floor slabs. Comparisons with high-fidelity finite-element model results are presented to verify the approach. Pushdown analyses of prototype buildings under column loss scenarios are performed using the reduced-order modeling approach, and an energy-based procedure is employed to account for the dynamic effects associated with sudden column loss. Results obtained using the energy-based approach are found to be in good agreement with results from direct dynamic analysis of sudden column loss. A metric for structural robustness is proposed, calculated by normalizing the ultimate capacities of the structural system under sudden column loss by the applicable service-level gravity loading and by evaluating the minimum value of this normalized ultimate capacity over all column removal scenarios. The procedure is applied to two prototype 10-story RC buildings, one employing intermediate moment frames (IMFs) and the other employing special moment frames (SMFs). The SMF building, with its more stringent seismic design and detailing, is found to have greater robustness.

  17. Evaluation of Control and Protection System for Loss of Electrical Power Supply System of Water-Cooling Nuclear Power Plant

    International Nuclear Information System (INIS)

    Suhaemi, Tjipta; Djen Djen; Setyono; Jambiar, Riswan; Rozali, Bang; Setyo P, Dwi; Tjahyono, Hendro

    2000-01-01

    Evaluation of control and protection system for loss of electrical power supply system of water-cooled nuclear power plant has been done. The loss of electrical power supply. The accident covered the loss of external electrical load and loss of ac power to the station auxiliaries. It is analysed by studying and observing the mechanism of electrical power system and mechanism of related control and protection system. The are two condition used in the evaluation i e without turbine trip and with turbine trip. From the evaluation it is concluded that the control and protection system can handled the failure caused by the loss of electrical power system

  18. Optimization of wheel-rail interface friction using top-of-rail friction modifiers: State of the art

    Science.gov (United States)

    Khan, M. Roshan; Dasaka, Satyanarayana Murty

    2018-05-01

    High Speed Railways and Dedicated Freight Corridors are the need of the day for fast and efficient transportation of the ever growing population and freight across long distances of travel. With the increase in speeds and axle loads carried by these trains, wearing out of rails and train wheel sections are a common issue, which is due to the increase in friction at the wheel-rail interfaces. For the cases where the wheel-rail interface friction is less than optimum, as in case of high speed trains with very low axle loads, wheel-slips are imminent and loss of traction occurs when the trains accelerate rapidly or brake all of a sudden. These vast variety of traction problems around the wheel-rail interface friction need to be mitigated carefully, so that the contact interface friction neither ascents too high to cause material wear and need for added locomotive power, nor be on the lower side to cause wheel-slips and loss of traction at high speeds. Top-of-rail friction modifiers are engineered surface coatings applied on top of rails, to maintain an optimum frictional contact between the train wheels and the rails. Extensive research works in the area of wheel-rail tribology have revealed that the optimum frictional coefficients at wheel-rail interfaces lie at a value of around 0.35. Application of top-of-rail (TOR) friction modifiers on rail surfaces add an extra layer of material coating on top of the rails, with a surface frictional coefficient of the desired range. This study reviews the common types of rail friction modifiers, the methods for their application, issues related with the application of friction modifiers, and a guideline on selection of the right class of coating material based on site specific requirements of the railway networks.

  19. Evaluation of a loss of residual heat removal event during mid-loop operation

    International Nuclear Information System (INIS)

    Seul, Kwang Won; Bang, Young Seok; Lee, Sukho; Kim, Hho Jung

    1996-01-01

    The potential for the RELAP5/MOD3.2 was assessed for the loss-of -RHR event during the mid-loop operation and the predictability of major thermal-hydraulic phenomena was also evaluated for the long term transient. The analysis results of the typical two cases(cold leg opening case and pressurizer opening case) were compared with experimental data which was conducted at ROSA-IV/LSTF in Japan. As a result, it was shown that the code was capable of simulating the thermal-hydraulic transport process with appropriate time step during the reduced inventory operation with the loss-of-RHR system

  20. 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.

  1. Postural Evaluation of Vertebral Column in Children and Teenagers with Hearing Loss

    Directory of Open Access Journals (Sweden)

    Toscano, Carla Fabiana da Silva

    2011-04-01

    Full Text Available Introduction: Posture is determined by the performance of the visual, somatosensory and vestibular systems. Children with hearing loss can present problems in their posture or postural control, enabling postural deviations and alterations to appear in their vertebral column, possibly provoked by a hypoactivity of the vestibular system as a result of deafness. Objective: To evaluate the posture of the vertebral column in children and teenagers with hearing loss at school age, taking into consideration the sample gender and age. Method: A descriptive and prospective study was performed at both Duque de Caxias School and Rotary Rehabilitation and Special Education Center in Caruaru - Pernambuco. 44 students aged between 7-17 years old, out of whom 22 were female and 22 were male, with hearing loss were evaluated. The study was developed by way of a postural evaluation, using a symmetrograph, marking specific anatomical points with stickers placed over polystyrene balls and fixed with double-sided adhesive tape. Results:The results showed that all of the individuals evaluated in this study presented some kind of postural alteration in their vertebral column. Scoliosis was the most observed alteration among the students (84.1%, followed by thoracic hyperkyphosis (68.2%. Conclusion: It has been concluded that children and teenagers with hearing loss are exposed to postural alteration in their vertebral column. Such a condition can be associated with a number of factors comprising unfavorable ergonomics of the school environment, bad postural habits and impairment of the vestibular system by virtue of the hearing loss.

  2. 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

  3. Evaluation of support loss in micro-beam resonators: A revisit

    Science.gov (United States)

    Chen, S. Y.; Liu, J. Z.; Guo, F. L.

    2017-12-01

    This paper presents an analytical study on evaluation of support loss in micromechanical resonators undergoing in-plane flexural vibrations. Two-dimensional elastic wave theory is used to determine the energy transmission from the vibrating resonator to the support. Fourier transform and Green's function technique are adopted to solve the problem of wave motions on the surface of the support excited by the forces transmitted by the resonator onto the support. Analytical expressions of support loss in terms of quality factor, taking into account distributed normal stress and shear stress in the attachment region, and coupling between the normal stress and shear stress as well as material disparity between the support and the resonator, have been derived. Effects of geometry of micro-beam resonators, and material dissimilarity between support and resonator on support loss are examined. Numerical results show that 'harder resonator' and 'softer support' combination leads to larger support loss. In addition, the Perfectly Matched Layer (PML) numerical simulation technique is employed for validation of the proposed analytical model. Comparing with results of quality factor obtained by PML technique, we find that the present model agrees well with the results of PML technique and the pure-shear model overestimates support loss noticeably, especially for resonators with small aspect ratio and large material dissimilarity between the support and resonator.

  4. Chemical origins of frictional aging.

    Science.gov (United States)

    Liu, Yun; Szlufarska, Izabela

    2012-11-02

    Although the basic laws of friction are simple enough to be taught in elementary physics classes and although friction has been widely studied for centuries, in the current state of knowledge it is still not possible to predict a friction force from fundamental principles. One of the highly debated topics in this field is the origin of static friction. For most macroscopic contacts between two solids, static friction will increase logarithmically with time, a phenomenon that is referred to as aging of the interface. One known reason for the logarithmic growth of static friction is the deformation creep in plastic contacts. However, this mechanism cannot explain frictional aging observed in the absence of roughness and plasticity. Here, we discover molecular mechanisms that can lead to a logarithmic increase of friction based purely on interfacial chemistry. Predictions of our model are consistent with published experimental data on the friction of silica.

  5. Microstructural Development in a TRIP-780 Steel Joined by Friction Stir Welding (FSW: Quantitative Evaluations and Comparisons with EBSD Predictions

    Directory of Open Access Journals (Sweden)

    Gladys Perez Medina

    Full Text Available Abstract The present work describes the effect of FSW on the result microstructure in the stir zone (SZ, thermo-mechanically affected zone (TMAZ, heat affected zone (HAZ and base metal (BM of a TRIP-780 steel. X-ray diffraction (XRD, optical microscopy (OM and EBSD were used for determinations retained austenite (RA in the SZ, It was found that the amount of RA developed in SZ was relatively large, (approximately 11% to 15%. In addition, recrystallization and the formation of a grain texture were resolved using EBSD. During FSW, the SZ experienced severe plastic deformation which lead to an increase in the temperature and consequently grain recrystallization. Moreover, it was found that the recrystallized grain structure and relatively high martensite levels developed in the SZ lead to a significant drop in the mechanical properties of the steel. In addition, microhardness profiles of the welded regions indicated that the hardness in both the SZ and TMAZ were relatively elevated confirming the development of martensite in these regions. In particular, to evaluate the mechanical strength of the weld, lap shear tensile test was conducted; exhibited the fracture zone in the SZ with shear fracture with uniformly distributed elongation shear dimples.

  6. Loss evaluation and design optimisation for direct driven permanent magnet synchronous generators for wind power

    Energy Technology Data Exchange (ETDEWEB)

    Eriksson, Sandra; Bernhoff, Hans [Swedish Centre for Renewable Electric Energy Conversion, Division for Electricity, Department of Engineering Sciences, Uppsala University, Box 534, 751 21 Uppsala (Sweden)

    2011-01-15

    When designing a generator for a wind turbine it is important to adapt the generator to the source, i.e. the wind conditions at the specific site. Furthermore, the variable speed operation of the generator needs to be considered. In this paper, electromagnetic losses in direct driven permanent magnet synchronous generators are evaluated through simulations. Six different generators are compared to each other. The simulations are performed by using an electromagnetic model, solved in a finite element environment and a control model developed in MATLAB. It is shown that when designing a generator it is important to consider the statistical wind distribution, control system, and aerodynamic efficiency in order to evaluate the performance properly. In this paper, generators with high overload capability are studied since they are of interest for this specific application. It is shown that a generator optimised for a minimum of losses will have a high overload capability. (author)

  7. Evaluation of damping loss factor of flat laminates by sound transmission

    Science.gov (United States)

    Parrinello, A.; Ghiringhelli, G. L.

    2018-06-01

    A novel approach to investigate and evaluate the damping loss factor of a planar multilayered structure is presented. A statistical analysis reveals the connection between the damping properties of the structure and the transmission of sound through the thickness of its laterally infinite counterpart. The obtained expression for the panel loss factor involves all the derivatives of the transmission and reflection coefficients of the layered structure with respect each layer damping. The properties of the fluid for which the sound transmission is evaluated are chosen to fulfil the hypotheses on the basis of the statistical formulation. A transfer matrix approach is used to compute the required transmission and reflection coefficients, making it possible to deal with structures having arbitrary stratifications of different layers and also granting high efficiency in a wide frequency range. Comparison with alternative formulations and measurements demonstrates the effectiveness of the proposed methodology.

  8. Evaluation of knowledge loss risk in nuclear industry and research organizations

    International Nuclear Information System (INIS)

    Constantin, Marin; Apostol, Minodora; Balaceanu, Victoria

    2007-01-01

    Institutional knowledge is defined as a collective knowledge of all employees in an organization or institution. The necessity to maintain organizational competency for nuclear power has been widely recognized given the nature of the business and the life cycle of 100 years or more. Our paper is intended to perform the first step in the knowledge loss risk assessment in nuclear organizations in Romania. Generally a three step procedure is needed for the evaluation process: - conducting the knowledge loss risk assessment; - determination of the approach needed to capture critical knowledge; - monitoring and evaluation. Taking into account the specificity of problems at organizational/institutional level, the difficulty of finding of a common approach, and the necessity to harmonize different interests at national level, a National Nuclear Knowledge Strategy is compulsory needed. (authors)

  9. Evaluation of Loss Due to Storm Surge Disasters in China Based on Econometric Model Groups

    OpenAIRE

    Xue Jin; Xiaoxia Shi; Jintian Gao; Tongbin Xu; Kedong Yin

    2018-01-01

    Storm surge has become an important factor restricting the economic and social development of China’s coastal regions. In order to improve the scientific judgment of future storm surge damage, a method of model groups is proposed to refine the evaluation of the loss due to storm surges. Due to the relative dispersion and poor regularity of the natural property data (login center air pressure, maximum wind speed, maximum storm water, super warning water level, etc.), storm surge disaster is di...

  10. Evaluation of heatup and recovery in a loss of feedwater accident with multiple failure

    International Nuclear Information System (INIS)

    Bang, Young Seok; Seul, Kwang Won; Kim, Hho Jung

    1991-01-01

    A loss of feedwater accident with multiple failure has been studied in order to identify the potential severity of the accident when compared with the design basis accident in PWR. The PCS heatup and recovery mode in a LOFA with multiple failure was evaluated using the LOFT L9-1/L3-3 experiment. From experimental result, 4 separable subphase were identified and the associated phenomena were also addressed

  11. Evaluation of bone loss due to primary occlusal trauma in two experimental models of occlusal overload

    OpenAIRE

    LOPES, Ana Cristina Távora de Albuquerque; TÉO, Mirela Anne Quartaroli; CORRÊA, Mônica Grazieli; ISHIKIRIAMA, Bella Luna Colombini; CAMPOS, Mirella Lindoso Gomes

    2016-01-01

    Abstract Introduction Primary occlusal trauma (OT) is an injury of the periodontium with normal height as a result of occlusal forces which exceed their adaptive capacity. Objective To evaluate, histometrically, the alveolar bone loss in the furcation region of rats experimentally submitted to 2 models of occlusal overload. Material and method 45 animals randomly divided into 3 groups: Occlusal Interference (OI, n = 15) - fixing an orthodontic wire segment on the occlusal surface of the fi...

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

    African Journals Online (AJOL)

    Frictional coefficient depending on active friction radius with BPV and BTV in automobile disc braking system. ... International Journal of Engineering, Science and Technology. Journal Home · ABOUT ... AJOL African Journals Online. HOW TO ...

  13. Idiopathic scoliosis: evaluation of loss of correction in postoperative follow-up

    Directory of Open Access Journals (Sweden)

    Liliane Faria Garcia

    2014-03-01

    Full Text Available OBJECTIVE: To evaluate the postoperative loss of scoliosis correction using third-generation instrumental, comparing the immediately postoperative period, and the last visit of the patients operated on from 2002 to 2010. METHOD: This was a cross-sectional study, conducted by analysis of medical records, in which 45 patients undergoing scoliosis correction were included. Variables were evaluated preoperatively, immediately postoperatively and in the last follow-up visit after surgery. Statistical analysis of data was performed in PASW program, with a significance level of 95%. RESULTS: Among the 45 patients studied, 88.9% were female and 82.8% were in the skeletally immature group. The mean pre-operative Cobb was 57°, the postoperative was 6.5° and at the last visit, it was 7.04°. There was no statistic difference between postoperative Cobb angle and that at the last examination (p = 0.176. CONCLUSION: There was no significant loss of scoliosis correction loss between the immediate postoperative and the final radiographic evaluation.

  14. Evaluation of Beam Loss and Energy Depositions for a Possible Phase II Design for LHC Collimation

    International Nuclear Information System (INIS)

    Lari, L.; Assmann, R.; Bracco, C.; Brugger, M.; Cerutti, F.; Doyle, E.; Ferrari, A.; Keller, L.; Lundgren, S.; Markiewicz, Thomas W.; Mauri, M.; Redaelli, S.; Sarchiapone, L.; Smith, J.; Vlachoudis, V.; Weiler, T.

    2011-01-01

    The LHC beams are designed to have high stability and to be stored for many hours. The nominal beam intensity lifetime is expected to be of the order of 20h. The Phase II collimation system has to be able to handle particle losses in stable physics conditions at 7 TeV in order to avoid beam aborts and to allow correction of parameters and restoration to nominal conditions. Monte Carlo simulations are needed in order to evaluate the behavior of metallic high-Z collimators during operation scenarios using a realistic distribution of losses, which is a mix of the three limiting halo cases. Moreover, the consequences in the IR7 insertion of the worst (case) abnormal beam loss are evaluated. The case refers to a spontaneous trigger of the horizontal extraction kicker at top energy, when Phase II collimators are used. These studies are an important input for engineering design of the collimation Phase II system and for the evaluation of their effect on adjacent components. The goal is to build collimators that can survive the expected conditions during LHC stable physics runs, in order to avoid quenches of the SC magnets and to protect other LHC equipments.

  15. Evaluation of Beam Losses And Energy Deposition for a Possible Phase II Design for LHC Collimation

    International Nuclear Information System (INIS)

    Lari, L.; Bracco, C.; Assmann, R.W.; Brugger, M.; Cerutti, F.; Ferrari, A.; Mauri, M.; Redaelli, S.; Sarchiapone, L.; Vlachoudis, V.; Weiler, T.; Doyle, J.E.; Keller, L.; Lundgren, S.A.; Markiewicz, T.W.; Smith, J.C.

    2011-01-01

    The Large Hadron Collider (LHC) beams are designed to have high stability and to be stored for many hours. The nominal beam intensity lifetime is expected to be of the order of 20h. The Phase II collimation system has to be able to handle particle losses in stable physics conditions at 7 TeV in order to avoid beam aborts and to allow correction of parameters and restoration to nominal conditions. Monte Carlo simulations are needed in order to evaluate the behavior of metallic high-Z collimators during operation scenarios using a realistic distribution of losses, which is a mix of the three limiting halo cases. Moreover, the consequences in the IR7 insertion of the worst (case) abnormal beam loss are evaluated. The case refers to a spontaneous trigger of the horizontal extraction kicker at top energy, when Phase II collimators are used. These studies are an important input for engineering design of the collimation Phase II system and for the evaluation of their effect on adjacent components. The goal is to build collimators that can survive the expected conditions during LHC stable physics runs, in order to avoid quenches of the SC magnets and to protect other LHC equipments.

  16. Evaluation of bone loss due to primary occlusal trauma in two experimental models of occlusal overload

    Directory of Open Access Journals (Sweden)

    Ana Cristina Távora de Albuquerque LOPES

    Full Text Available Abstract Introduction Primary occlusal trauma (OT is an injury of the periodontium with normal height as a result of occlusal forces which exceed their adaptive capacity. Objective To evaluate, histometrically, the alveolar bone loss in the furcation region of rats experimentally submitted to 2 models of occlusal overload. Material and method 45 animals randomly divided into 3 groups: Occlusal Interference (OI, n = 15 - fixing an orthodontic wire segment on the occlusal surface of the first lower molar; Occlusal Overload (OO, n = 15 - wearing of the cusps of the lower contralateral molars, the second and third molars next to the first molar that had its dimensions maintained; Negative Control (NC, n = 15 - evaluation of the initial dimensions of the periodontal ligament (PL. Five animals / group were sacrificed after 14, 21 and 28 days. Result Intergroup evaluation showed significant bone loss in OI (p0.05. The thickness of the PL remained stable in NC (p>0.05. Conclusion OI and OO were effective in the experimental reproduction of OT, and OI promoted greater alveolar bone loss compared to OO, showing that the impact of occlusal overload in OI increased the extent of the OT injury.

  17. Evaluating Land Subsidence Rates and Their Implications for Land Loss in the Lower Mississippi River Basin

    Directory of Open Access Journals (Sweden)

    Lei Zou

    2015-12-01

    Full Text Available High subsidence rates, along with eustatic sea-level change, sediment accumulation and shoreline erosion have led to widespread land loss and the deterioration of ecosystem health around the Lower Mississippi River Basin (LMRB. A proper evaluation of the spatial pattern of subsidence rates in the LMRB is the key to understanding the mechanisms of the submergence, estimating its potential impacts on land loss and the long-term sustainability of the region. Based on the subsidence rate data derived from benchmark surveys from 1922 to 1995, this paper constructed a subsidence rate surface for the region through the empirical Bayesian kriging (EBK interpolation method. The results show that the subsidence rates in the region ranged from 1.7 to 29 mm/year, with an average rate of 9.4 mm/year. Subsidence rates increased from north to south as the outcome of both regional geophysical conditions and anthropogenic activities. Four areas of high subsidence rates were found, and they are located in Orleans, Jefferson, Terrebonne and Plaquemines parishes. A projection of future landscape loss using the interpolated subsidence rates reveals that areas below zero elevation in the LMRB will increase from 3.86% in 2004 to 19.79% in 2030 and 30.88% in 2050. This translates to a growing increase of areas that are vulnerable to land loss from 44.3 km2/year to 240.7 km2/year from 2011 to 2050. Under the same scenario, Lafourche, Plaquemines and Terrebonne parishes will experience serious loss of wetlands, whereas Orleans and Jefferson parishes will lose significant developed land, and Lafourche parish will endure severe loss of agriculture land.

  18. Internal friction in uranium

    International Nuclear Information System (INIS)

    Selle, J.E.

    1975-01-01

    Results are presented of studies conducted to relate internal friction measurements in U to allotropic transformations. It was found that several internal friction peaks occur in α-uranium whose magnitude changed drastically after annealing in the β phase. All of the allotropic transformations in uranium are diffusional in nature under slow heating and cooling conditions. Creep at regions of high stress concentration appears to be responsible for high temperature internal friction in α-uranium. The activation energy for grain boundary relaxation in α-uranium was found to be 65.1 +- 4 kcal/mole. Impurity atoms interfere with the basic mechanism for grain boundary relaxation resulting in a distribution in activation energies. A considerable distribution in ln tau 0 was also found which is a measure of the distribution in local order and in the Debye frequency around a grain boundary

  19. Damage Tolerance Behavior of Friction Stir Welds in Aluminum Alloys

    Science.gov (United States)

    McGill, Preston; Burkholder, Jonathan

    2012-01-01

    Friction stir welding is a solid state welding process used in the fabrication of various aerospace structures. Self-reacting and conventional friction stir welding are variations of the friction stir weld process employed in the fabrication of cryogenic propellant tanks which are classified as pressurized structure in many spaceflight vehicle architectures. In order to address damage tolerance behavior associated with friction stir welds in these safety critical structures, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size. Test data describing fracture behavior, residual strength capability, and cyclic mission life capability of friction stir welds at ambient and cryogenic temperatures have been generated and will be presented in this paper. Fracture behavior will include fracture toughness and tearing (R-curve) response of the friction stir welds. Residual strength behavior will include an evaluation of the effects of lack of penetration on conventional friction stir welds, the effects of internal defects (wormholes) on self-reacting friction stir welds, and an evaluation of the effects of fatigue cycled surface cracks on both conventional and selfreacting welds. Cyclic mission life capability will demonstrate the effects of surface crack defects on service load cycle capability. The fracture data will be used to evaluate nondestructive inspection and proof test requirements for the welds.

  20. Accurate solutions of Colebrook-White's friction factor formulae ...

    African Journals Online (AJOL)

    Estimations of friction factor (Ff) in pipeline systems and fluid transport are essential ingredients in engineering fields and processes. In this paper explicit friction factor formulae (Fff) were proposed and evaluated with an aim of developing error free Fff. General Fff that relate Ff, Reynolds number (Re) and relative roughness ...

  1. Effect of hexagonal boron nitride and calcined petroleum coke on friction and wear behavior of phenolic resin-based friction composites

    International Nuclear Information System (INIS)

    Yi Gewen; Yan Fengyuan

    2006-01-01

    Calcined petroleum coke (CPC) and hexagonal boron nitride (h-BN) were used as the friction modifiers to improve the friction and wear properties of phenolic resin-based friction composites. Thus, the composites with different relative amounts of CPC and h-BN as the friction modifiers were prepared by compression molding. The hardness and bending strength of the friction composites were measured. The friction and wear behaviors of the composites sliding against cast iron at various temperatures were evaluated using a pin-on-disc test rig. The worn surfaces and wear debris of the friction composites were analyzed by means of scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. It was found that the hybrid of the two friction modifiers was effective to significantly decrease the wear rate and stabilize the friction coefficient of the friction composites at various temperatures by forming a uniform lubricating and/or transferred film on the rubbing surfaces. The uniform and durable transfer films were also able to effectively diminish the direct contact between the friction composite and the cast iron counterpart and hence prevent severe wear of the latter as well. The effectiveness of the hybrid of CPC and h-BN in improving the friction and wear behavior of the phenolic resin-based friction modifiers could be attributed to the complementary action of the 'low temperature' lubricity of CPC and the 'high temperature' lubricity of h-BN. The optimum ratio of the two friction modifiers CPC and h-BN in the friction composites was suggested to be 1:1, and the corresponding friction composite showed the best friction-reducing and antiwear abilities

  2. Thermoelastic Loss in Microscale Oscillators

    National Research Council Canada - National Science Library

    Houston, B. H; Photiadis, D. M; Marcus, M. H; Bucaro, J. A; Liu, Xiao; Vignola, J. F

    2001-01-01

    ...) and nanoelectromechanical (NEMS) oscillators. The theory defines a flexural modal participation factor, the fraction of potential energy stored in flexure, and approximates the internal friction by assuming the energy loss to occur solely via...

  3. Evaluation of the apparent losses caused by water meter under-registration in intermittent water supply.

    Science.gov (United States)

    Criminisi, A; Fontanazza, C M; Freni, G; Loggia, G La

    2009-01-01

    Apparent losses are usually caused by water theft, billing errors, or revenue meter under-registration. While the first two causes are directly related to water utility management and may be reduced by improving company procedures, water meter inaccuracies are considered to be the most significant and hardest to quantify. Water meter errors are amplified in networks subjected to water scarcity, where users adopt private storage tanks to cope with the intermittent water supply. The aim of this paper is to analyse the role of two variables influencing the apparent losses: water meter age and the private storage tank effect on meter performance. The study was carried out in Palermo (Italy). The impact of water meter ageing was evaluated in laboratory by testing 180 revenue meters, ranging from 0 to 45 years in age. The effects of the private water tanks were determined via field monitoring of real users and a mathematical model. This study demonstrates that the impact on apparent losses from the meter starting flow rapidly increases with meter age. Private water tanks, usually fed by a float valve, overstate meter under-registration, producing additional apparent losses between 15% and 40% for the users analysed in this study.

  4. Labour market frictions and migration

    NARCIS (Netherlands)

    Cremers, Jan

    2016-01-01

    The 4th contribution to the series INT-AR papers is dedicated to the methods of assessing labour market frictions. The paper provides a (brief) international comparison of the role of labour migration in solving these frictions.

  5. Skin friction related behaviour of artificial turf systems.

    Science.gov (United States)

    Tay, Sock Peng; Fleming, Paul; Hu, Xiao; Forrester, Steph

    2017-08-01

    The occurrence of skin friction related injuries is an issue for artificial turf sports pitches and remains a barrier to their acceptance. The purpose of this study was to evaluate the current industry standard Securisport® Sports Surface Tester that measures skin surface related frictional behaviour of artificial turf. Little research has been published about the device and its efficacy, despite its widespread use as a standard FIFA test instrument. To achieve a range of frictional behaviours, several "third generation" (3G) carpet and infill combinations were investigated; friction time profiles throughout the Securisport rotations were assessed in combination with independent measurements of skin roughness before and after friction testing via 3D surface scanning. The results indicated that carpets without infill had greatest friction (coefficients of friction 0.97-1.20) while those completely filled with sand or rubber had similar and lower values independent of carpet type (coefficient of friction (COF) ≈0.57). Surface roughness of a silicone skin (s-skin) decreased after friction testing, with the largest change on sand infilled surfaces, indicating an "abrasive" polishing effect. The combined data show that the s-skin is damaged in a surface-specific manner, thus the Securisport COF values appear to be a poor measure of the potential for skin abrasion. It is proposed that the change in s-skin roughness improves assessment of the potential for skin damage when players slide on artificial turf.

  6. In vitro evaluation of frictional forces of two ceramic orthodontic brackets versus a stainless steel bracket in combination with two types of archwires.

    Science.gov (United States)

    Arash, Valiollah; Rabiee, Mahmoud; Rakhshan, Vahid; Khorasani, Sara; Sobouti, Farhad

    2015-01-01

    The aim of this study was to compare frictional forces between monocrystalline alumina (MA), polycrystalline alumina (PA), and stainless steel (SS) brackets with two SS wires: Rectangular and round. In this in vitro study, 60 0.022 brackets [20 PA (0° torque, Forestadent, Germany) and 20 MA (0° torque, Ormco, California, USA)] brackets plus 20 SS brackets (0° torque, Foretadent, Germany) and 60 SS archwires (30 rectangular 0.019 ×0.025 archwires and 30 round 0.018 archwires, Ortho Technology, USA) were used in subgroups of 10 from the combination of all brackets and all archwires. A universal testing machine (Instron, Model STM 250, Germany) was used to investigate the static frictional resistance. The angulation between the bracket and wire was 0°, and the wires were pulled through the slots at a crosshead speed of 10 mm/min. Two-way and one-way analyses of variance (ANOVA) and Tukey tests were used to analyze the data. Mean (SD) static frictional force for each group was as follows: MA + round: 3.47 (0.38); MA + rectangular: 4.05 (0.47); PA + round: 4.14 (0.37); PA + rectangular: 4.45 (0.65); SS + round: 3.28 (0.22); and SS + rectangular: 4.22 (0.61). Significant effects of bracket types (P = 0.001) and archwire types (P = 0.000) on the friction force were detected using ANOVA. Tukey test indicated significant differences between PA brackets with both SS and MA brackets (P brackets. The two archwires as well had significantly different effects (Tukey P = 0.000). Based on the present in-vitro study, the PA brackets might create higher frictional forces compared to both SS and MA brackets. The rectangular 0.019 ×0.025 archwire might create greater forces than round 0.018 archwire.

  7. In vitro evaluation of frictional forces of two ceramic orthodontic brackets versus a stainless steel bracket in combination with two types of archwires

    Science.gov (United States)

    Arash, Valiollah; Rabiee, Mahmoud; Rakhshan, Vahid; Khorasani, Sara; Sobouti, Farhad

    2015-01-01

    Purpose: The aim of this study was to compare frictional forces between monocrystalline alumina (MA), polycrystalline alumina (PA), and stainless steel (SS) brackets with two SS wires: Rectangular and round. Materials and Methods: In this in vitro study, 60 0.022 brackets [20 PA (0° torque, Forestadent, Germany) and 20 MA (0° torque, Ormco, California, USA)] brackets plus 20 SS brackets (0° torque, Foretadent, Germany) and 60 SS archwires (30 rectangular 0.019 ×0.025 archwires and 30 round 0.018 archwires, Ortho Technology, USA) were used in subgroups of 10 from the combination of all brackets and all archwires. A universal testing machine (Instron, Model STM 250, Germany) was used to investigate the static frictional resistance. The angulation between the bracket and wire was 0°, and the wires were pulled through the slots at a crosshead speed of 10 mm/min. Two-way and one-way analyses of variance (ANOVA) and Tukey tests were used to analyze the data. Results: Mean (SD) static frictional force for each group was as follows: MA + round: 3.47 (0.38); MA + rectangular: 4.05 (0.47); PA + round: 4.14 (0.37); PA + rectangular: 4.45 (0.65); SS + round: 3.28 (0.22); and SS + rectangular: 4.22 (0.61). Significant effects of bracket types (P = 0.001) and archwire types (P = 0.000) on the friction force were detected using ANOVA. Tukey test indicated significant differences between PA brackets with both SS and MA brackets (P brackets. The two archwires as well had significantly different effects (Tukey P = 0.000). Conclusions: Based on the present in-vitro study, the PA brackets might create higher frictional forces compared to both SS and MA brackets. The rectangular 0.019 ×0.025 archwire might create greater forces than round 0.018 archwire. PMID:26020037

  8. Evaluation of precipitates used in strainer head loss testing. Part I. Chemically generated precipitates

    International Nuclear Information System (INIS)

    Bahn, Chi Bum; Kasza, Ken E.; Shack, William J.; Natesan, Ken; Klein, Paul

    2009-01-01

    The purpose of the current program was to evaluate the properties of chemical precipitates proposed by industry that have been used in sump strainer head loss testing. Specific precipitates that were evaluated included aluminum oxyhydroxide (AlOOH) and sodium aluminum silicate (SAS) prepared according to the procedures in WCAP-16530-NP, along with precipitates formed from injecting chemicals into the test loop according to the procedure used by one sump strainer test vendor for U.S. pressurized water reactors. The settling rates of the surrogate precipitates are strongly dependent on their particle size and are reasonably consistent with those expected from Stokes' Law or colloid aggregation models. Head loss tests showed that AlOOH and SAS surrogates are quite effective in increasing the head loss across a perforated pump inlet strainer that has an accumulated fibrous debris bed. The characteristics of aluminum hydroxide precipitate using sodium aluminate were dependent on whether it was formed in high-purity or ordinary tap water and whether excess silicate was present or not.

  9. Cooking loss, tenderness, and sensory evaluation of chicken meat roasted after wrapping with edible films.

    Science.gov (United States)

    Küçüközet, Ahmet Oktay; Uslu, Mustafa Kemal

    2018-01-01

    In this study, edible films were produced from sodium caseinate and a sodium caseinate-starch mixture and with or without oleoresins (cumin and oregano oleoresin mixture). Chicken meat was wrapped in the respective films, stored at 4 ℃ for four days, and roasted at 200 ℃ for 30 min. The cooking loss, color changes, instrumental tenderness (shear force and energy) were measured. In addition, sensory evaluation was performed. All films effectively reduced cooking loss from chicken meat. The sodium caseinate-starch-based films were the most successful in preventing cooking loss. The average shear force and shear energy values of the wrapped samples were about 40% and 30% less than those of control samples, respectively. In sensory evaluation, chicken meat roasted after wrapping with the films was considered more tender and delicious than the control. Particularly, chicken meat wrapped with the films containing oleoresin mixture was assessed as the most delicious among the samples. It was shown that the cooking quality of the chicken meat could be significantly improved by pre-wrapping the meat with edible films.

  10. Friction in sheet metal forming

    DEFF Research Database (Denmark)

    Wiklund, D.; Liljebgren, M.; Berglund, J.

    2010-01-01

    and calls for functional tool surfaces that are durable in these severe tribological conditions. In this study the influence of tool surface topography on friction has been investigated. The frictional response was studied in a Bending Under Tension test. The results did show that a low frictional response...

  11. EVALUATING DEGREE OF ACTIVE POWER LOSSES REDUCTION IN THE ELECTRIC POWER LINES WITH REACTIVE POWER COMPENSATION

    Directory of Open Access Journals (Sweden)

    V. N. Radkevich

    2016-01-01

    Full Text Available The paper considers evaluation procedure for the degree of active power losses reduction in the power transmission lines under 1 kV and 6–10 kV of the systems of electric power supply of industrial enterprises with compensating installations mounted at the side of the customer. The capacitor installations conform to the applied voltage level and factor in dielectric losses in the capacitors. The voltage at the compensating device terminal changes from 0.95 to 1.05 of the capacitors nominal voltage. The study did not account for reactive power losses in the line, nor did it for its charge capacity, conditioned by relative shortness of the cable lines generally operating in the mains of industrial enterprises. For this reason, the quantities of reactive power being consumed and generated by the transmission line are negligible and do not significantly affect the reactive power flux. The researchers obtain functional relations that allow estimating the degree of power loss reduction in the transmission line factoring in its explicit initial data. They perform mathematical analysis of the obtained functional relations and study the function by means of derivatives. The function extremum points are found as well as the intervals of its increment and decrement. A graphical research of the obtained functional relation is performed. It is ascertained that reduction of the active power losses is contingent on the line and the capacitor-installation engineering factors, the electrical energy consumer reactive load value as well as the voltage applied to the capacitor installation. The functional relations presented in the article can be employed in scoping calculation necessary for decision making on the reactive power compensation in systems of the industrial facilities electric power supply. Their account will allow a more accurate estimate of technical and economic effect of the capacitor bank installation in the electrical mains under 1 kV and 6

  12. Pandemic of Pregnant Obese Women: Is It Time to Re-Evaluate Antenatal Weight Loss?

    Directory of Open Access Journals (Sweden)

    Anne M. Davis

    2015-08-01

    Full Text Available The Obesity pandemic will afflict future generations without successful prevention, intervention and management. Attention to reducing obesity before, during and after pregnancy is essential for mothers and their offspring. Preconception weight loss is difficult given that many pregnancies are unplanned. Interventions aimed at limiting gestational weight gain have produced minimal maternal and infant outcomes. Therefore, increased research to develop evidence-based clinical practice is needed to adequately care for obese pregnant women especially during antenatal care. This review evaluates the current evidence of obesity interventions during pregnancy various including weight loss for safety and efficacy. Recommendations are provided with the end goal being a healthy pregnancy, optimal condition for breastfeeding and prevent the progression of obesity in future generations.

  13. Intelligent Flow Friction Estimation.

    Science.gov (United States)

    Brkić, Dejan; Ćojbašić, Žarko

    2016-01-01

    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 10(8) 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.

  14. 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...

  15. Skin tribology: Science friction?

    NARCIS (Netherlands)

    van der Heide, Emile; Zeng, Xiangqiong; Masen, Marc Arthur

    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

  16. Coulomb Friction Damper

    Science.gov (United States)

    Appleberry, W. T.

    1983-01-01

    Standard hydraulic shock absorber modified to form coulomb (linear friction) damper. Device damps very small velocities and is well suited for use with large masses mounted on soft springs. Damping force is easily adjusted for different loads. Dampers are more reliable than fluid dampers and also more economical to build and to maintain.

  17. 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.

  18. Friction welding method

    International Nuclear Information System (INIS)

    Ishida, Ryuichi; Hatanaka, Tatsuo.

    1969-01-01

    A friction welding method for forming a lattice-shaped base and tie plate supporter for fuel elements is disclosed in which a plate formed with a concavity along its edge is pressure welded to a rotating member such as a boss by longitudinally contacting the projecting surfaces remaining on either side of the concavity with the rotating member during the high speed rotation thereof in the presence of an inert gas. Since only the two projecting surfaces of the plate are fused by friction to the rotary member, heat expansion is absorbed by the concavity to prevent distortion; moreover, a two point contact surface assures a stable fitting and promotes the construction of a rigid lattice in which a number of the abovementioned plates are friction welded between rotating members to form any desired complex arrangement. The inert has serves to protect the material quality of the contacting surfaces from air during the welding step. The present invention thus provides a method in which even Zircaloy may be friction welded in place of casting stainless steel in the construction of supporting lattices to thereby enhance neutron economy. (K. J. Owens)

  19. Development of an Evaluation Methodology for Loss of Large Area induced from extreme events

    International Nuclear Information System (INIS)

    Kim, Sok Chul; Park, Jong Seuk; Kim, Byung Soon; Jang, Dong Ju; Lee, Seung Woo

    2015-01-01

    USNRC announced several regulatory requirements and guidance documents regarding the event of loss of large area including 10CFR 50.54(hh), Regulatory Guide 1.214 and SRP 19.4. In Korea, consideration of loss of large area has been limitedly taken into account for newly constructing NPPs as voluntary based. In general, it is hardly possible to find available information on methodology and key assumptions for the assessment of LOLA due to 'need to know based approach'. Urgent needs exists for developing country specific regulatory requirements, guidance and evaluation methodology by themselves with the consideration of their own geographical and nuclear safety and security environments. Currently, Korea Hydro and Nuclear Power Company (KHNP) has developed an Extended Damage Mitigation Guideline (EDMG) for APR1400 under contract with foreign consulting company. The submittal guidance NEI 06-12 related to B.5.b Phase 2 and 3 focused on unit-wise mitigation strategy instead of site level mitigation or response strategy. Phase 1 mitigating strategy and guideline for LOLA (Loss of Large Area) provides emphasis on site level arrangement including cooperative networking outside organizations and agile command and control system. Korea Institute of Nuclear Safety has carried out a pilot in-house research project to develop the methodology and guideline for evaluation of LOLA since 2014. This paper introduces the summary of major results and outcomes of the aforementioned research project. After Fukushima Dai-Ichi accident, the awareness on countering the event of loss of large area induced from extreme man-made hazards or extreme beyond design basis external event. Urgent need exists to develop regulatory guidance for coping with this undesirable situation, which has been out of consideration at existing nuclear safety regulatory framework due to the expectation of rare possibility of occurrence

  20. Evaluation and diagnosis of the hair loss patient: part II. Trichoscopic and laboratory evaluations.

    Science.gov (United States)

    Mubki, Thamer; Rudnicka, Lidia; Olszewska, Malgorzata; Shapiro, Jerry

    2014-09-01

    The use of trichoscopy for evaluating a number of hair and scalp disorders is gaining popularity. It is a simple and noninvasive in vivo tool for visualizing hair shafts and the scalp. Recently, alopecias have been classified according to their trichoscopic findings. The second part of this 2-part continuing medical education article reviews recent advances in this field and describes a systematic approach for using the differential diagnostic findings of trichoscopy in alopecia. Copyright © 2014 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

  1. 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.

  2. Validation of measured friction by process tests

    DEFF Research Database (Denmark)

    Eriksen, Morten; Henningsen, Poul; Tan, Xincai

    The objective of sub-task 3.3 is to evaluate under actual process conditions the friction formulations determined by simulative testing. As regards task 3.3 the following tests have been used according to the original project plan: 1. standard ring test and 2. double cup extrusion test. The task...... has, however, been extended to include a number of new developed process tests: 3. forward rod extrusion test, 4. special ring test at low normal pressure, 5. spike test (especially developed for warm and hot forging). Validation of the measured friction values in cold forming from sub-task 3.1 has...... been made with forward rod extrusion, and very good agreement was obtained between the measured friction values in simulative testing and process testing....

  3. Routine magnetic resonance imaging for idiopathic olfactory loss: a modeling-based economic evaluation.

    Science.gov (United States)

    Rudmik, Luke; Smith, Kristine A; Soler, Zachary M; Schlosser, Rodney J; Smith, Timothy L

    2014-10-01

    Idiopathic olfactory loss is a common clinical scenario encountered by otolaryngologists. While trying to allocate limited health care resources appropriately, the decision to obtain a magnetic resonance imaging (MRI) scan to investigate for a rare intracranial abnormality can be difficult. To evaluate the cost-effectiveness of ordering routine MRI in patients with idiopathic olfactory loss. We performed a modeling-based economic evaluation with a time horizon of less than 1 year. Patients included in the analysis had idiopathic olfactory loss defined by no preceding viral illness or head trauma and negative findings of a physical examination and nasal endoscopy. Routine MRI vs no-imaging strategies. We developed a decision tree economic model from the societal perspective. Effectiveness, probability, and cost data were obtained from the published literature. Litigation rates and costs related to a missed diagnosis were obtained from the Physicians Insurers Association of America. A univariate threshold analysis and multivariate probabilistic sensitivity analysis were performed to quantify the degree of certainty in the economic conclusion of the reference case. The comparative groups included those who underwent routine MRI of the brain with contrast alone and those who underwent no brain imaging. The primary outcome was the cost per correct diagnosis of idiopathic olfactory loss. The mean (SD) cost for the MRI strategy totaled $2400.00 ($1717.54) and was effective 100% of the time, whereas the mean (SD) cost for the no-imaging strategy totaled $86.61 ($107.40) and was effective 98% of the time. The incremental cost-effectiveness ratio for the MRI strategy compared with the no-imaging strategy was $115 669.50, which is higher than most acceptable willingness-to-pay thresholds. The threshold analysis demonstrated that when the probability of having a treatable intracranial disease process reached 7.9%, the incremental cost-effectiveness ratio for MRI vs no

  4. Effect of Friction Model and Tire Maneuvering on Tire-Pavement Contact Stress

    OpenAIRE

    Haichao Zhou; Guolin Wang; Yangmin Ding; Jian Yang; Chen Liang; Jing Fu

    2015-01-01

    This paper aims to simulate the effects of different friction models on tire braking. A truck radial tire (295/80R22.5) was modeled and the model was validated with tire deflection. An exponential decay friction model that considers the effect of sliding velocity on friction coefficients was adopted for analyzing braking performance. The result shows that the exponential decay friction model used for evaluating braking ability meets design requirements of antilock braking system (ABS). The ti...

  5. Evaluation of the Vestibular System and Etiology in Children with Unilateral Sensorineural Hearing Loss.

    Science.gov (United States)

    Birdane, Leman; İncesulu, Armağan; Özüdoğru, Erkan; Cingi, Cemal; Caklı, Hamdi; Gürbüz, Melek Kezban; Adapınar, Baki

    2016-08-01

    The aim of this study was to evaluate the vestibular system of children with unilateral sensorineural hearing loss (USNHL), investigate the etiological factors of USNHL and analyze whether a genetic predisposition exists. Thirty-three children aged less than 18 years with USNHL, who visited the ear, nose, and throat (ENT) department between January 2004 and December 2012, were included in this study. Cases with conductive hearing loss were excluded from the study. The patients were subjected to etiologic, genetic, and ophthalmologic evaluation; radiologic imaging; electronystagmography (ENG); and vestibular evoked myogenic potential (VEMP) tests. The control group, which included 25 healthy children (13 males and 12 females), had undergone audiological assessment and were subjected to ENG and VEMP tests. All of the patients had severe-to-profound hearing loss. Mumps immunoglobulin G was positive in 22 (66.7%) of 33 patients. The 35delG mutation was not found in any of the patients. All of the patients underwent temporal computed tomography (CT) and magnetic resonance imaging (MRI). Inner ear anomaly was present in 51.5% of the patients. Overall, 21 of 31 ENG patients had canal paresis in the affected ear. The VEMP response was absent on the affected side in three patients. The n23 latency average of the patient group was longer than that of the control group. Because USNHL causes irreversible problems in children, early diagnosis and auditory rehabilitation are very important. As USNHL is accompanied by inner ear anomaly, children with USNHL should undergo temporal bone CT and MRI. To evaluate the vestibular system, ENG and VEMP are non-invasive and diagnostic tests.

  6. Evaluation of postulated LOF [loss-of-flow] events in PRISM and SAFR

    International Nuclear Information System (INIS)

    Chan, B.C.; Van Tuyle, G.J.; Slovik, G.C.; Aronson, A.L.

    1987-01-01

    The PRISM and SAFR designs, as currently proposed by DOE, are designed for ''inherent'', as opposed to ''engineered'', safety. Brookhaven National Laboratory is supporting the initial NRC review of these advanced LMR concepts. A loss-of-flow (LOF) accident coupled with a failure of the reactor shutdown system is one of the major safety concerns in the advanced liquid metal reactor (LMR) evaluation effort. The analysis discussed here covers: (1) primary pipe break without pump trip, (2) primary coolant pump seizure, and (3) primary coolant pump coastdown. The analytical modelling and the calculated thermal and hydraulic behavior are described in detail

  7. Optoelectronic Evaluation and Loss Analysis of PEDOT:PSS/Si Hybrid Heterojunction Solar Cells.

    Science.gov (United States)

    Yang, Zhenhai; Fang, Zebo; Sheng, Jiang; Ling, Zhaoheng; Liu, Zhaolang; Zhu, Juye; Gao, Pingqi; Ye, Jichun

    2017-12-01

    The organic/silicon (Si) hybrid heterojunction solar cells (HHSCs) have attracted considerable attention due to their potential advantages in high efficiency and low cost. However, as a newly arisen photovoltaic device, its current efficiency is still much worse than commercially available Si solar cells. Therefore, a comprehensive and systematical optoelectronic evaluation and loss analysis on this HHSC is therefore highly necessary to fully explore its efficiency potential. Here, a thoroughly optoelectronic simulation is provided on a typical planar polymer poly (3,4-ethylenedioxy thiophene):polystyrenesulfonate (PEDOT:PSS)/Si HHSC. The calculated spectra of reflection and external quantum efficiency (EQE) match well with the experimental results in a full-wavelength range. The losses in current density, which are contributed by both optical losses (i.e., reflection, electrode shield, and parasitic absorption) and electrical recombination (i.e., the bulk and surface recombination), are predicted via carefully addressing the electromagnetic and carrier-transport processes. In addition, the effects of Si doping concentrations and rear surface recombination velocities on the device performance are fully investigated. The results drawn in this study are beneficial to the guidance of designing high-performance PEDOT:PSS/Si HHSCs.

  8. Evaluate of head loss, sediment value and copper removal in sand media (rapid sand filter

    Directory of Open Access Journals (Sweden)

    Daneshi Navab

    2014-06-01

    Full Text Available Along with the technology development and increasing consumption of water resources, we are experiencing low qualities in the mentioned resources. Copper brings about serious environment al pollution, threatening human health and ecosystem. This metal found variously in water resources and industrial activities. Therefore, it needs to treat the water resources from these excessive amounts. Different methods have used for this reason but the most used method during recent years has been the absorption by economic absorbers such as sand. Rapid sand filters usually used in water and wastewater treatment plants for water clarification. In this research, a single layer gravity rapid sand filter has used to reduce different concentrations of copper. sediment value and head loss arising in filter media is simulated by using combination of Carman-Kozeny, Rose and Gregory models in different discharges of rapid sand filter. Results have shown that with increasing in discharge and decreasing in input copper concentration, arriving time to given head loss, is increasing. In addition, results demonstrated that with increasing in copper concentration in influent, removal efficiency is decreasing somewhat. Results of this research can applied in an appropriate design of rapid sand filter to copper removal, a prediction of rapid sand filter ability to copper removal and an estimation of arising head loss during filter work thus evaluating of time interval backwash. DOI: http://dx.doi.org/10.3126/ije.v3i2.10641 International Journal of the Environment Vol.3(2 2014: 276-286

  9. Advances in the Understanding of the Genetic Causes of Hearing Loss in Children Inform a Rational Approach to Evaluation.

    Science.gov (United States)

    Carey, John C; Palumbos, Janice C

    2016-10-01

    Hearing loss represents the most common sensory disability of children. Remarkable advances in the identification of genes underlying nonsyndromic and syndromic hearing loss in just the last 2 decades have led to the ability to determine the specific genetic cause of hearing loss in many children. Surprisingly one gene, GJB2, encoding the protein connexin-26, accounts for about 20 % of sensorineural hearing loss (including in India) and is considered the first tier test in evaluating an infant with unexplained congenital hearing loss. Using the knowledge of the etiology of hearing loss, the authors propose a diagnostic reasoning process for the assessment of a child in the pediatric setting. Second tier testing consists of the multiple gene panels using whole exome sequencing strategies, and is becoming available in some regions of the world including the US. Referral to medical genetics is always a consideration in a child with no explanation for the hearing loss and in families with questions about recurrence risk.

  10. Evaluation of the Survival Rate and Bone Loss of Implants with Various Lengths

    Directory of Open Access Journals (Sweden)

    AR. Rokn

    2006-12-01

    Full Text Available Statement of Problem: The replacement of missing teeth with implant-associated restorations has become a widely used treatment modality in recent years. The length of dental implants may be a critical factor in achieving and maintaining osseointegration.Purpose: The aim of this study was to evaluate the survival rate and bone loss of dental implants with different lengthsMaterials and Methods: A retrospective cohort study was performed on 60 ITI-system implants, evenly distributed into three groups including 8, 10 and 12 mm high implants in the posterior segments of both jaws. Demographic information, oral hygiene,cigarette smoking, implant length, duration of implant placement (at least 24 months,bleeding on probing index and pocket probing depth were recorded for all participants.Bone loss was calculated using pre- and post-operative panoramic radiographs.Results: The mean rate of bone loss was different among the three groups and were found to be 0.21 (0.45, 0.3 (0.41 and 0.43 (0.55 mm in the 8, 10, and 12 mm high implants, respectively. Neither mean bone loss nor bleeding on probing index showed significant differences with implant length. A significant correlation was found between implant length and pocket probing depth (P<0.0001.Conclusion: The results of this study suggest that both short (8 mm high and long (10 or 12 mm high implants may be used with nearly equal success rates in the posterior segments of the jaws.

  11. The Relationship between Habitat Loss and Fragmentation during Urbanization: An Empirical Evaluation from 16 World Cities.

    Directory of Open Access Journals (Sweden)

    Zhifeng Liu

    Full Text Available Urbanization results in habitat loss and habitat fragmentation concurrently, both influencing biodiversity and ecological processes. To evaluate these impacts, it is important to understand the relationships between habitat loss and habitat fragmentation per se (HLHF during urbanization. The objectives of this study were two-fold: 1 to quantify the different forms of the HLHF relationship during urbanization using multiple landscape metrics, and 2 to test the validity of the HLHF relations reported in the literature. Our analysis was based on a long-term urbanization dataset (1800-2000 of 16 large cities from around the world. Habitat area was represented as the percentage of non-built-up area in the landscape, while habitat fragmentation was measured using several landscape metrics. Our results show that the relationship between habitat loss and habitat fragmentation during urbanization is commonly monotonic-linear, exponential, or logarithmic, indicating that the degree of habitat fragmentation per se increases with habitat loss in general. We compared our results with 14 hypothesized HLHF relationships based on simulated landscapes found in the literature, and found that four of them were consistent with those of urbanization, whereas the other ten were not. Also, we identified six new HLHF relationships when fragmentation was measured by total core area, normalized total core area, patch density, edge density and landscape shape index, respectively. In addition, our study demonstrated that the "space-for-time" approach, frequently used in ecology and geography, generated specious HLHF relationships, suggesting that this approach is largely inappropriate for analyses of urban landscapes that are highly heterogeneous in space and unusually contingent in dynamics. Our results show both generalities and idiosyncrasies of the HLHF relationship, providing new insights for assessing ecological effects of urbanization.

  12. Evaluation of mitigation strategies to reduce ammonia losses from slurry fertilisation on arable lands

    Energy Technology Data Exchange (ETDEWEB)

    Carozzi, M., E-mail: marco.carozzi@unimi.it [University of Milan, Department of Agricultural and Environmental Sciences, via Celoria 2, 20133 Milan (Italy); Ferrara, R.M.; Rana, G. [Consiglio per la Ricerca e sperimentazione in Agricoltura, Research Unit for Cropping Systems in Dry Environments, via C. Ulpiani, 5 – 70125 Bari (Italy); Acutis, M. [University of Milan, Department of Agricultural and Environmental Sciences, via Celoria 2, 20133 Milan (Italy)

    2013-04-01

    To evaluate the best practices in reducing ammonia (NH{sub 3}) losses from fertilised arable lands, six field trials were carried out in three different locations in northern Italy. NH{sub 3} emissions from cattle slurry were estimated considering the spreading techniques and the field incorporation procedures. The measurements were performed using long term exposure samplers associated to the determination of the atmospheric turbulence and the use of the backward Lagrangian stochastic (bLS) model WindTrax. The results obtained indicate that the NH{sub 3} emission process was exhausted in the first 24–48 h after slurry spreading. The slurry incorporation technique was able to reduce the NH{sub 3} losses with respect to the surface spreading, where a contextual incorporation led to reductions up to 87%. However, the best abatement strategy for NH{sub 3} losses from slurry applications has proved to be the direct injection into the soil, with a reduction of about 95% with respect to the surface spreading. The results obtained highlight the strong dependence of the volatilisation phenomenon by soil and weather conditions. - Highlights: ► Ammonia emissions from land-application of slurry were quantified. ► We examined and compared six different agronomic treatments in three locations. ► The faster was the soil-incorporation of slurry, the lower was the ammonia loss. ► The direct injection of slurry was found to be the best abatement strategy. ► The environmental factors were able to strongly influence the ammonia emission.

  13. Optimum design of brake friction material using hybrid entropy-GRA approach

    Directory of Open Access Journals (Sweden)

    Kumar Naresh

    2016-01-01

    Full Text Available The effect of Kevlar and natural fibres on the performance of brake friction materials was evaluated. Four friction material specimens were developed by varying the proportion of Kevlar and natural fibres. Two developed composite contained 5-10 wt.% of Kevlar fibre while in the other two the Kevlar fibre was replaced with same amount of natural fibre. SAE J661 protocol was used for the assessment of the tribological properties on a Chase testing machine. Result shows that the specimens containing Kevlar fibres shows higher friction and wear performance, whereas Kevlar replacement with natural fibre resulted in improved fade, recovery and friction fluctuations. Further hybrid entropy-GRA (grey relation analysis approach was applied to select the optimal friction materials using various performance defining attributes (PDA including friction, wear, fade, recovery, friction fluctuations and cost. The friction materials with 10 wt% of natural fibre exhibited the best overall quality.

  14. Evaluation of total loss of feedwater accident/recovery phase and investigation of the associated EOP

    International Nuclear Information System (INIS)

    Bang, Young Seok; Seul, Kwang Won; Kim, Hho Jung

    1993-01-01

    To evaluate the sequence of event and the thermohydraulic behavior during total loss of feedwater accident and recovery procedure, a RELAP5/MOD3 calculation is performed and compared with the LOFT L9-1/L3-3 experiment. Also, the predictability of the code for the major thermohydraulic phenomena following the accident is assessed. As a result, it is found that a pressure control using the spray until the time the water level reaches the top of the pressurizer, an overpressure protection by pressurizer PORV, a recovery of the secondary heat removal capability by refilling steam generator, and an effective cooldown by the continued natural circulation can be perfomed without core uncovery. It is also found that the plantspecific evaluation is necessary to confirm the effectiveness of the current symptom-oriented emergency operating procedure, especially in an overpressure protection performance and steam generator recovery performance. (Author)

  15. Biological evaluation of devices used for reducing entrainment and impingement losses at thermal power plants

    International Nuclear Information System (INIS)

    Cada, G.F.; Szluha, A.T.

    1978-01-01

    A preliminary survey of fish protection devices either in use or proposed for water intake structures was conducted for the purpose of assessing their potential for reducing impingement and entrainment. All the designs examined can be divided into two basic categories: behavioral screening systems and physical screening systems. The behavioral screening devices rely upon the ability of fish to sense artificial stimuli and respond by swimming away from hazardous areas. These systems are of little or no value in protecting planktonic fish eggs, larvae, and disoriented, heat-shocked, or lethargic adult fishes. Many of the physical screening devices, on the other hand, require the impingement of organisms against a screen before they can be removed from the intake system, thus subjecting survival. Some of the designs incorporate both behavioral and physical sceening concepts. Six devices were selected for further consideration based on their potential or demonstrated effectiveness in reducing impingement and entrainment losses at a variety of intake situations. The structures evaluated were modified vertical traveling screens, louvers, angled vertical traveling screens, horizontal traveling screens, center-flow screens, and wedge-wire screens. Since some of these intake structures represent new concepts, few laboratory or in situ biological studies have been carried out. For others, actual reductions in fish losses have been demonstrated. The design features and status of biological testing is discussed for each device, and an evaluation of their fish protection potential is presented

  16. 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.

  17. The effect of ligation method on friction in sliding mechanics.

    Science.gov (United States)

    Hain, Max; Dhopatkar, Ashish; Rock, Peter

    2003-04-01

    During orthodontic tooth movement with the preadjusted edgewise system, friction generated at the bracket/archwire interface tends to impede the desired movement. The method of ligation is an important contributor to this frictional force. This in vitro study investigated the effect of ligation method on friction and evaluated the efficacy of the new slick elastomeric modules from TP Orthodontics (La Porte, Ind), which are claimed to reduce friction at the module/wire interface. Slick modules were compared with regular nonslick modules, stainless steel ligatures, and the SPEED self-ligating bracket system (Strite Industries, Cambridge, Ontario, Canada). The effect of using slick modules with metal-reinforced ceramic (Clarity, 3M Unitek, Monrovia, Calif) and miniature brackets (Minitwin, 3M Unitek) was also examined. Results showed that, when considering tooth movement along a 0.019 x 0.025-in stainless steel archwire, saliva-lubricated slick modules can reduce static friction at the module/archwire interface by up to 60%, regardless of the bracket system. The SPEED brackets produced the lowest friction compared with the 3 other tested bracket systems when regular modules were used. The use of slick modules, however, with all of the ligated bracket types tested significantly reduced friction to below the values recorded in the SPEED groups. Loosely tied stainless steel ligatures were found to generate the least friction.

  18. Evaluation of Loss Resources during Sugarcane Production Process and Provide Solutions to Reduce Waste

    Directory of Open Access Journals (Sweden)

    H Zakidizaji

    2018-03-01

    Full Text Available Introduction No use of advanced mechanization and weakness in post harvesting technology are the main reasons of agricultural losses. Some of these wastes (agricultural losses are related to crop growing conditions in field and the remaining to processing of sugar in mill. The most useful priority setting methods for agricultural projects are the Analytic Hierarchy Process (AHP. So, this study presents an introduction of application manner of the AHP as a mostly common method of setting agricultural projects priorities. The purpose of this work is studying the sugarcane loss during production process using AHP in Khuzestan province. Materials and Methods The resources of sugarcane waste have been defined based on expert’s opinions. A questionnaire and personal interviews have formed the basis of this research. The study was applied to a panel of qualified informants made up of thirty-two experts. Those interviewed were distributed in Sugarcane Development and By-products Company in 2015-2016. Then, with using the analytical hierarchy process, a questionnaire was designed for defining the weight and importance of parameters effecting on sugarcane waste. For this method of evaluation, three main criteria considered, were yield criteria, cost criteria and income criteria. Criteria and prioritizing of them was done by questionnaire and interview with sophisticated experts. This technique determined and ranked the importance of sugarcane waste resources based on attributing relative weights to factors with respect to comments provided in the questionnaires. Analytical Hierarchy Process was done by using of software (Expert choice and the inconsistency rate on expert judgments was investigated. Results and Discussion How to use agricultural implements and machinery during planting and harvesting of sugarcane, can increase or decrease the volume of waste. In planting period, the losses mainly consists of loss of setts during cutting them by machine

  19. Geometric singular perturbation analysis of systems with friction

    DEFF Research Database (Denmark)

    Bossolini, Elena

    This thesis is concerned with the application of geometric singular perturbation theory to mechanical systems with friction. The mathematical background on geometric singular perturbation theory, on the blow-up method, on non-smooth dynamical systems and on regularization is presented. Thereafter......, two mechanical problems with two different formulations of the friction force are introduced and analysed. The first mechanical problem is a one-dimensional spring-block model describing earthquake faulting. The dynamics of earthquakes is naturally a multiple timescale problem: the timescale...... scales. The action of friction is generally explained as the loss and restoration of linkages between the surface asperities at the molecular scale. However, the consequences of friction are noticeable at much larger scales, like hundreds of kilometers. By using geometric singular perturbation theory...

  20. Skin friction on a flat perforated acoustic liner

    Science.gov (United States)

    Boldman, D. R.; Brinich, P. F.

    1976-01-01

    The report concerns the measurement of friction coefficients of a typical perforated acoustic liner installed in the side of a wind tunnel. The results are compared with measured friction coefficients of a smooth hard wall for the same mean flow velocities in a wind tunnel. At a velocity of 61 m/sec, an increase in the local skin coefficient of only a few percent was observed, but at the highest velocity of 213 m/sec an increase of about 20% was obtained. This velocity is a realistic velocity for turbo-machinery components utilizing such liners, so a loss in performance is to be expected. Some tests were also performed to see if changes in the mean boundary layer induced by imposed noise would result in friction increase, but only at low velocity levels was such an increase in friction noted.

  1. Thermodynamical Description of Running Discontinuities: Application to Friction and Wear

    Directory of Open Access Journals (Sweden)

    Claude Stolz

    2010-06-01

    Full Text Available The friction and wear phenomena appear due to contact and relative motion between two solids. The evolution of contact conditions depends on loading conditions and mechanical behaviours. The wear phenomena are essentially characterized by a matter loss. Wear and friction are in interaction due to the fact that particles are detached from the solids. A complex medium appears as an interface having a strong effect on the friction condition. The purpose of this paper is to describe such phenomena taking account of different scales of modelization in order to derive some macroscopic laws. A thermodynamical approach is proposed and models of wear are analysed in this framework where the separation between the dissipation due to friction and that due to wear is made. Applications on different cases are presented.

  2. Identification of GMS friction model without friction force measurement

    International Nuclear Information System (INIS)

    Grami, Said; Aissaoui, Hicham

    2011-01-01

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

  3. Hearing Screening and Diagnostic Evaluation of Children With Unilateral and Mild Bilateral Hearing Loss

    OpenAIRE

    Ross, Danielle S.; Holstrum, W. June; Gaffney, Marcus; Green, Denise; Oyler, Robert F.; Gravel, Judith S.

    2008-01-01

    More than 90% of newborns in the United States are now being screened for hearing loss. A large fraction of cases of unilateral hearing loss and mild bilateral hearing loss are not currently identified through newborn hearing screening. This is of concern because a preponderance of research has demonstrated that unilateral hearing loss and mild bilateral hearing loss can lead to developmental delays and educational problems for some children. To help address this probable underidentification ...

  4. Experimental evaluation of ability of Relap5, Drako, Flowmaster2TM and program using unsteady wall friction model to calculate water hammer loadings on pipelines

    International Nuclear Information System (INIS)

    Marcinkiewicz, Jerzy; Adamowski, Adam; Lewandowski, Mariusz

    2008-01-01

    Mechanical loadings on pipe systems caused by water hammer (hydraulic transients) belong to the most important and most difficult to calculate design loadings in nuclear power plants. The most common procedure in Sweden is to calculate the water hammer loadings on pipe segments, according to the classical one-dimensional (1D) theory of liquid transient flow in a pipeline, and then transfer the results to strength analyses of pipeline structure. This procedure assumes that there is quasi-steady respond of the pipeline structure to pressure surges-no dynamic interaction between the fluid and the pipeline construction. The hydraulic loadings are calculated with 1D so-called 'network' programs. Commonly used in Sweden are Relap5, Drako and Flowmaster2-all using quasi-steady wall friction model. As a third party accredited inspection body Inspecta Nuclear AB reviews calculations of water hammer loadings. The presented work shall be seen as an attempt to illustrate ability of Relap5, Flowmaster2 and Drako programs to calculate the water hammer loadings. A special attention was paid to using of Relap5 for calculation of water hammer pressure surges and forces (including some aspects of influence of Courant number on the calculation results) and also the importance of considering the dynamic (or unsteady) friction models. The calculations are compared with experimental results. The experiments have been conducted at a test rig designed and constructed at the Szewalski Institute of Fluid Flow Machinery of the Polish Academy of Sciences (IMP PAN) in Gdansk, Poland. The analyses show quite small differences between pressures and forces calculated with Relap5, Flowmaster2 and Drako (the differences regard mainly damping of pressure waves). The comparison of calculated and measured pressures and also a force acting on a pre-defined pipe segment shows significant differences. It is shown that the differences can be reduced by using unsteady friction models in calculations

  5. 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.

  6. Evaluation to Mitigate Secondary System Peak Pressure for Loss of Condenser Vacuum Event

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Bong Oh; Park, Jong Cheol; Park, Min Soo; Lee, Gyu Cheon; Kim, Shin Whan [KEPCO E and C, Inc., Daejeon (Korea, Republic of)

    2015-10-15

    In this paper, countermeasures to compensate the increased secondary pressure are introduced and evaluated. From the standpoint of the secondary system pressurization, consideration of the PPCS may result in a conservative secondary system peak pressure. The control systems are generally credited for the safety analysis if the analysis produces conservative results. However, in most of all non-loss of coolant accident (non-LOCA) events, the control system helps to mitigate a transient state. Accordingly, the safety analysis of non-LOCA assumes the control systems are in the manual mode of operation. The loss of condenser vacuum event (LOCV) is a typical anticipated operational occurrence (AOO) which results in an increase in primary and secondary system pressure. The pressurizer (PZR) pressure control system (PPCS) will function to reduce the primary system pressure increase during the transient. Therefore, it is assumed to be in manual mode and credit is not taken for its functioning. However, crediting the function of PPCS has been found to be more conservative with regard to the secondary system pressure. This is due to the delay of the reactor trip on high pressurizer pressure (HPP) and results in an increase in secondary pressure.

  7. Evaluating the consequences of loss of flow accident for a typical VVER-1000 nuclear reactor

    Energy Technology Data Exchange (ETDEWEB)

    Mirvakili, S.M.; Safaei, S. [Shiraz Univ., Shiraz (Iran, Islamic Republic of). Dept. of Nuclear Engineering, School of Mechanical Engineering; Faghihi, F. [Shiraz Univ., Shiraz (Iran, Islamic Republic of). Safety Research Center

    2010-07-01

    The loss of coolant flow in a nuclear reactor can result from a mechanical or electrical failure of the coolant pump. If the reactor is not tripped promptly, the immediate effect is a rapid increase in coolant temperature, decrease in minimum departure from nucleate boiling ratio (DNBR) and fuel damage. This study evaluated the shaft seizure of a reactor coolant pump in a VVER-1000 nuclear reactor. The locked rotor results in rapid reduction of flow through the affected reactor coolant loop and in turn leads to an increase in the primary coolant temperature and pressure. The analysis was conducted with regard for superimposing loss of power to the power plant at the initial accident moment. The required transient functions of flow, pressure and power were obtained using system transient calculations applied in COBRA-EN computer code in order to calculate the overall core thermal-hydraulic parameters such as temperature, critical heat flux and DNBR. The study showed that the critical period for the locked rotor accident is the first few seconds during which the maximum values of pressure and temperature are reached. 10 refs., 1 tab., 3 figs.

  8. 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

  9. Evaluation of iron and selenium losses in metalloproteins separated by gel electrophoresis by ICPMS

    International Nuclear Information System (INIS)

    Gherghel, I.; Fernandez, M.L.; Fernandez, B.; Pereiro, R.; Sanz-Medel, A.

    2009-01-01

    Full text: Metallomics addresses the study of metabolism, transport, and metal-protein interactions aiming to obtain relevant information of physiological and pathological alterations in living organisms. Gel electrophoresis is widely employed in proteomics and its use is actually extending to metallomics. Unfortunately, analysis of proteins by molecular techniques does not offer quantitative information. So, a good alternative could be their determination via the quantification of (semi)metal bound to the protein by ICPMS. In this work, we will show a detailed study of possible losses of protein and/or metal in Fe-bound and selenium proteins (transferrin and glutathione peroxidase, respectively) to evaluate the behaviour of the protein-metal interactions during the electrophoresis process. (author)

  10. Evaluation of the risk of noise-induced hearing loss among unscreened male industrial workers

    Science.gov (United States)

    Prince, Mary M.; Gilbert, Stephen J.; Smith, Randall J.; Stayner, Leslie T.

    2003-02-01

    Variability in background risk and distribution of various risk factors for hearing loss may explain some of the diversity in excess risk of noise-induced hearing loss (NIHL). This paper examines the impact of various risk factors on excess risk estimates of NIHL using data from the 1968-1972 NIOSH Occupational Noise and Hearing Survey (ONHS). Previous analyses of a subset of these data focused on 1172 highly ``screened'' workers. In the current analysis, an additional 894 white males (609 noise-exposed and 285 controls), who were excluded for various reasons (i.e., nonoccupational noise exposure, otologic or medical conditions affecting hearing, prior occupational noise exposure) have been added (n=2066) to assess excess risk of noise-induced material impairment in an unscreened population. Data are analyzed by age, duration of exposure, and sound level (8-h TWA) for four different definitions of noise-induced hearing impairment, defined as the binaural pure-tone average (PTA) hearing threshold level greater than 25 dB for the following frequencies: (a) 1-4 kHz (PTA1234), (b) 1-3 kHz (PTA123), (c) 0.5, 1, and 2 kHz (PTA512), and (d) 3, 4, and 6 kHz (PTA346). Results indicate that populations with higher background risks of hearing loss may show lower excess risks attributable to noise relative to highly screened populations. Estimates of lifetime excess risk of hearing impairment were found to be significantly different between screened and unscreened population for noise levels greater than 90 dBA. Predicted age-related risk of material hearing impairment in the ONHS unscreened population was similar to that predicted from Annex B and C of ANSI S3.44 for ages less than 60 years. Results underscore the importance of understanding differential risk patterns for hearing loss and the use of appropriate reference (control) populations when evaluating risk of noise-induced hearing impairment among contemporary industrial populations.

  11. Evaluation of fluid intake, weight loss and sweat rate in young triathletes

    Directory of Open Access Journals (Sweden)

    María Cristina Sellés López de Castro

    2015-10-01

    Full Text Available Introduction: Triathlon is an endurance sport comprising three disciplines: swimming, cycling and running. It is necessary to purpose guidelines in order to avoid dehydration during training or competition and keep good hydration before, during and after physical activity. The aim of this study is to evaluation of fluid intake, weight loss and sweat rate in young triathletes, during different trainings.Material and Methods: A descriptive-observational study in 14 triathletes (7 boys and 7 girls during a session of swimming, other session of cycling, another session of running. Fluid intake, weight loss, % of total body water, % dehydration and sweat rate, were assessed. Triathletes drank water in their drums of 750 ml and urine measurement was performed in containers.Results: The results of our study following the next order: swimming, cycling and running. Water intake 2.66±1.94ml/min, 7.91±7.69ml/min y 7.08±4.13ml/min in boys and 3.43±1.53ml/min, 6.39±5.36ml/min y 8.33±2.74ml/min in girls; weight loss 0.83±0.5kg, 0.47±0.3kg y 0.98±0.4kg in boys and 0.79±0.3kg, 0.47±0.58kg y 0.28±0.21kg in girls; and sweating rate 4.44±4.9ml/ min, 11.81±6.46ml/min y 5.29±3.13ml/min in boys and 3.89±2.4ml/min, 4.69±4.20ml/min and 7.96±5.06ml/min in girls.Conclusions: The percentage of body water and dehydration, loss of weight and sweat rate were compared with other studies and it´s shown that our results are lower than others studies, being below the recommendations of liquid intake in athletes.

  12. Digital radiographic evaluation of alveolar bone loss, density and lamina dura integrity on post splinting mandibular anterior with chronic periodontitis

    Science.gov (United States)

    Rafini, F.; Priaminiarti, M.; Sukardi, I.; Lessang, R.

    2017-08-01

    The healing of periodontal splinting can be detected both with clinical and radiographic examination. In this study, the alveolar bone was evaluated by radiographic digital periapical analysis. Periodontal tooth splinting is periodontal support therapy used to prevent periodontal injury during repair and regeneration of periodontal therapy. Radiographic digital periapical analysis of alveolar bone in the mandibular anterior region with chronic periodontitis and 2/3 cervical bone loss after three months of periodontal splinting. Eighty four proximal site (43 mesial and 41 distal) from 16 patients with chronic periodontitis and treated with spinting were examined by taking periapical digital radiographic at day 1 and 91. The bone loss, bone density and utility of lamina dura were evaluated. The statistical analysis after three months evaluation using T-test for bone loss, Wilcoxon sign rank test for bone density and utility lamina dura showed no significantly differences (pchronic periodontitis with 2/3 alveolar bone loss after three months splinting.

  13. 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

  14. 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

  15. Evaluation of the Effect of Split application of Urea on Nitrogen Losses in Furrow Fertigation

    Directory of Open Access Journals (Sweden)

    farid feizolahpour

    2017-01-01

    different splits and amounts of fertilizer consumption. Eventually, fertigation treatments were compared with traditional treatments (fertilizer broadcasting method. According to the obtained results, evaluate the interactions of the effect of split × N usage showed that, the fourth treatment (60% of fertilizer application in 4 splits can be suggested, owing to its lower N losses by runoff. In addition there were no statistical significant differences of grain yield between the fourth and fifth treatments (100% of fertilizer application in 3 splits. Consequently, it can be concluded that by the usage of 60 percent of the recommended fertilizer application in four equal splits during the growing season, the potential of environmental pollution will be reduced while achieving optimal performance.

  16. Evaluation of precipitates used in strainer head loss testing: Part II. Precipitates by in situ aluminum alloy corrosion

    International Nuclear Information System (INIS)

    Bahn, Chi Bum; Kasza, Ken E.; Shack, William J.; Natesan, Ken; Klein, Paul

    2011-01-01

    Graphical abstract: Display Omitted Research highlights: → Sump strainer head loss testing to evaluate chemical effects. → Aluminum hydroxide precipitates by in situ Al alloy corrosion caused head loss. → Intermetallic particles released from Al alloy can also cause significant head loss. → When evaluating Al effect on head loss, intermetallics should be considered. - Abstract: Vertical loop head loss tests were performed with 6061 and 1100 aluminum (Al) alloy plates immersed in borated solution at pH = 9.3 at room temperature and 60 o C. The results suggest that the potential for corrosion of an Al alloy to result in increased head loss across a glass fiber bed may depend on its microstructure, i.e., the size distribution and number density of intermetallic particles that are present in Al matrix and FeSiAl ternary compounds, as well as its Al release rate. Per unit mass of Al removed from solution, the WCAP-16530 aluminum hydroxide (Al(OH) 3 ) surrogate was more effective in increasing head loss than the Al(OH) 3 precipitates formed in situ by corrosion of Al alloy. However, in choosing a representative amount of surrogate for plant specific testing, consideration should be given to the potential for additional head losses due to intermetallic particles and the apparent reduction in the effective solubility of Al(OH) 3 when intermetallic particles are present.

  17. Evaluation of Extended-Wear Hearing Technology for Children with Hearing Loss.

    Science.gov (United States)

    Wolfe, Jace; Schafer, Erin; Martella, Natalie; Morais, Mila; Mann, Misty

    2015-01-01

    Research shows that many older children and teenagers who have mild to moderately severe sensorineural hearing loss do not use their hearing instruments during all waking hours. A variety of reasons may contribute toward this problem, including concerns about cosmetics associated with hearing aid use and the inconvenience of daily maintenance associated with hearing instruments. Extended-wear hearing instruments are inserted into the wearer's ear canal by an audiologist and are essentially invisible to outside observers. The goal of this study was to evaluate the potential benefits and limitations associated with use of extended-wear hearing instruments in a group of children with hearing loss. A two-way repeated measures design was used to examine performance differences obtained with the participants' daily-wear hearing instruments versus that obtained with extended-wear hearing instruments. Sixteen children, ages 10-17 yr old, with sensorineural hearing loss ranging from mild to moderately severe. Probe microphone measures were completed to evaluate the aided output of device. Behavioral test measures included word recognition in quiet, sentence recognition in noise, aided warble-tone thresholds, and psychophysical loudness scaling. Questionnaires were also administered to evaluate subjective performance with each hearing technology. Data logging suggested that many participants were not using their daily-wear hearing instruments during all waking hours (mean use was less than 6 h/day). Real ear probe microphone measurements indicated that a closer fit to the Desired Sensation Level Version 5 prescriptive targets was achieved with the children's daily-wear instruments when compared to the extended-wear instruments. There was no statistically significant difference in monosyllabic word recognition at 50 or 60 dBA obtained with the two hearing technologies. Sentence recognition in noise obtained with use of the extended-wear devices was, however, significantly

  18. 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.

  19. Friction in levitated superconductors

    International Nuclear Information System (INIS)

    Brandt, E.H.

    1988-01-01

    A type I superconductor levitated above a magnet of low symmetry has a unique equilibrium position about which it may oscillate freely. In contrast, a type II superconductor has a continuous range of stable equilibrium positions and orientations where it floats rigidly without swinging or orbiting as if it were stuck in sand. A strong internal friction conspicuously indicates the existence and unpinning of flux lines in oxide superconductors levitated above liquid nitrogen. It is shown how these effects follow from the hysteretic magnetization curves and how the energy is dissipated

  20. 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

  1. 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

  2. MEASUREMENT OF FRICTIONAL PRESSURE DIFFERENTIALS DURING A VENTILATION SURVEY

    International Nuclear Information System (INIS)

    B.S. Prosser, PE; I.M. Loomis, PE, PhD

    2003-01-01

    During the course of a ventilation survey, both airflow quantity and frictional pressure losses are measured and quantified. The measurement of airflow has been extensively studied as the vast majority of ventilation standards/regulations are tied to airflow quantity or velocity. However, during the conduct of a ventilation survey, measurement of airflow only represents half of the necessary parameters required to directly calculate the airway resistance. The measurement of frictional pressure loss is an often misunderstood and misapplied part of the ventilation survey. This paper compares the two basic methods of frictional pressure drop measurements; the barometer and the gauge and tube. Personal experiences with each method will be detailed along with the authors' opinions regarding the applicability and conditions favoring each method

  3. Precise measurement of velocity dependent friction in rotational motion

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Junaid; Hassan, Hafsa; Shamim, Sohaib; Mahmood, Waqas; Anwar, Muhammad Sabieh, E-mail: sabieh@lums.edu.pk [School of Science and Engineering, Lahore University of Management Sciences (LUMS), Opposite Sector U, D.H.A, Lahore 54792 (Pakistan)

    2011-09-15

    Frictional losses are experimentally determined for a uniform circular disc exhibiting rotational motion. The clockwise and anticlockwise rotations of the disc, that result when a hanger tied to a thread is released from a certain height, give rise to vertical oscillations of the hanger as the thread winds and unwinds over a pulley attached to the disc. It is thus observed how the maximum height is achieved by the hanger decrements in every bounce. From the decrements, the rotational frictional losses are measured. The precision is enhanced by correlating vertical motion with the angular motion. This method leads to a substantial improvement in precision. Furthermore, the frictional torque is shown to be proportional to the angular speed. The experiment has been successfully employed in the undergraduate lab setting.

  4. Single-Nucleotide Polymorphism-Microarray Ploidy Analysis of Paraffin-Embedded Products of Conception in Recurrent Pregnancy Loss Evaluations.

    Science.gov (United States)

    Maslow, Bat-Sheva L; Budinetz, Tara; Sueldo, Carolina; Anspach, Erica; Engmann, Lawrence; Benadiva, Claudio; Nulsen, John C

    2015-07-01

    To compare the analysis of chromosome number from paraffin-embedded products of conception using single-nucleotide polymorphism (SNP) microarray with the recommended screening for the evaluation of couples presenting with recurrent pregnancy loss who do not have previous fetal cytogenetic data. We performed a retrospective cohort study including all women who presented for a new evaluation of recurrent pregnancy loss over a 2-year period (January 1, 2012, to December 31, 2013). All participants had at least two documented first-trimester losses and both the recommended screening tests and SNP microarray performed on at least one paraffin-embedded products of conception sample. Single-nucleotide polymorphism microarray identifies all 24 chromosomes (22 autosomes, X, and Y). Forty-two women with a total of 178 losses were included in the study. Paraffin-embedded products of conception from 62 losses were sent for SNP microarray. Single-nucleotide polymorphism microarray successfully diagnosed fetal chromosome number in 71% (44/62) of samples, of which 43% (19/44) were euploid and 57% (25/44) were noneuploid. Seven of 42 (17%) participants had abnormalities on recurrent pregnancy loss screening. The per-person detection rate for a cause of pregnancy loss was significantly higher in the SNP microarray (0.50; 95% confidence interval [CI] 0.36-0.64) compared with recurrent pregnancy loss evaluation (0.17; 95% CI 0.08-0.31) (P=.002). Participants with one or more euploid loss identified on paraffin-embedded products of conception were significantly more likely to have an abnormality on recurrent pregnancy loss screening than those with only noneuploid results (P=.028). The significance remained when controlling for age, number of losses, number of samples, and total pregnancies. These results suggest that SNP microarray testing of paraffin-embedded products of conception is a valuable tool for the evaluation of recurrent pregnancy loss in patients without prior fetal

  5. Comparative Evaluation of the Loss and Thermal Performance of Advanced Three Level Inverter Topologies

    DEFF Research Database (Denmark)

    Anthon, Alexander; Zhang, Zhe; Andersen, Michael A. E.

    2016-01-01

    . The first solution directly replaces the 1200 V primary Si IGBT switches with lower loss 1200 V SiC MOSFETs. The second solution strategically adds 600 V CoolMos FET devices to the conventional Si T-Type inverter to reduce the primary commutation losses. Semiconductor loss models, experimentally verified...

  6. Component evaluation for intersystem loss-of-coolant accidents in advanced light water reactors

    International Nuclear Information System (INIS)

    Ware, A.G.

    1994-07-01

    Using the methodology outlined in NUREG/CR-5603 this report evaluates (on a probabilistic basis) design rules for components in ALWRs that could be subjected to intersystem loss-of-coolant accidents (ISLOCAs). The methodology is intended for piping elements, flange connections, on-line pumps and valves, and heat exchangers. The NRC has directed that the design rules be evaluated for BWR pressures of 7.04 MPa (1025 psig), PWR pressures of 15.4 MPa (2235 psig), and 177 degrees C (350 degrees F), and has established a goal of 90% probability that system rupture will not occur during an ISLOCA event. The results of the calculations in this report show that components designed for a pressure of 0.4 of the reactor coolant system operating pressure will satisfy the NRC survival goal in most cases. Specific recommendations for component strengths for BWR and PWR applications are made in the report. A peer review panel of nationally recognized experts was selected to review and critique the initial results of this program

  7. Internal friction, microstructure, and radiation effects

    International Nuclear Information System (INIS)

    Wechsler, M.S.; Sommer, W.F.; Davidson, D.R.

    1984-01-01

    A brief review is given of internal friction relaxation peaks and background internal friction. The microstructural origin of the internal friction is discussed. Particular emphasis is placed on radiation effects

  8. Evaluating the effect placement capacitor and distributed photovoltaic generation for power system losses minimization in radial distribution system

    Science.gov (United States)

    Rahman, Yuli Asmi; Manjang, Salama; Yusran, Ilham, Amil Ahmad

    2018-03-01

    Power loss minimization have many advantagess to the distribution system radial among others reduction of power flow in feeder lines, freeing stress on feeder loading, deterrence of power procurement from the grid and also the cost of loss compensating instruments. This paper, presents capacitor and photovoltaic (PV) placement as alternative means to decrease power system losses. The paper aims to evaluate the best alternative for decreasing power system losses and improving voltage profile in the radial distribution system. To achieve the objectives of paper, they are used three cases tested by Electric Transient and Analysis Program (ETAP) simulation. Firstly, it performs simulation of placement capacitor. Secondly, simulated placement of PV. Lastly, it runs simulation of placement capacitor and PV simultaneously. The simulations were validated using the IEEE 34-bus test system. As a result, they proved that the installation of capacitor and PV integration simultaneously leading to voltage profile correction and power losses minimization significantly.

  9. 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.

  10. Evaluating radon loss from water during storage in standard PET, bio-based PET, and PLA bottles

    International Nuclear Information System (INIS)

    Lucchetti, Carlo; De Simone, Gabriele; Galli, Gianfranco; Tuccimei, Paola

    2016-01-01

    Polyethylene terephthalate (PET) and polylactic acid (PLA) bottles were tested to evaluate radon loss from water during 15 days of storage. PET bottles (lower surface/volume-ratio vials) lost 0.4–7.1% of initial radon, whereas PLA bottles lost 3.7% of it. PET bottles with volume of 0.5 L, lower surface/weight ratio, and hence higher thickness display proportionally reduced radon loss. Corrections for dissolved radium are needed during analyses. Formulas for calculating degassing efficiency and water interference on electrostatic collections are developed. - Highlights: • Radon loss from water during storage in polyethylene terephthalate (PET) and polylactic acid (PLA) bottles was evaluated. • Surface/volume ratio and thickness of plastic materials were studied. • A correction for dissolved radium concentration was applied to estimate gas loss. • Proper corrections for degassing efficiency of aerators were developed. • The interference of H 2 O on radon daughter electrostatic collection was quantified.

  11. 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

  12. Friction laws at the nanoscale.

    Science.gov (United States)

    Mo, Yifei; Turner, Kevin T; Szlufarska, Izabela

    2009-02-26

    Macroscopic laws of friction do not generally apply to nanoscale contacts. Although continuum mechanics models have been predicted to break down at the nanoscale, they continue to be applied for lack of a better theory. An understanding of how friction force depends on applied load and contact area at these scales is essential for the design of miniaturized devices with optimal mechanical performance. Here we use large-scale molecular dynamics simulations with realistic force fields to establish friction laws in dry nanoscale contacts. We show that friction force depends linearly on the number of atoms that chemically interact across the contact. By defining the contact area as being proportional to this number of interacting atoms, we show that the macroscopically observed linear relationship between friction force and contact area can be extended to the nanoscale. Our model predicts that as the adhesion between the contacting surfaces is reduced, a transition takes place from nonlinear to linear dependence of friction force on load. This transition is consistent with the results of several nanoscale friction experiments. We demonstrate that the breakdown of continuum mechanics can be understood as a result of the rough (multi-asperity) nature of the contact, and show that roughness theories of friction can be applied at the nanoscale.

  13. 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

  14. Friction between footwear and floor covered with solid particles under dry and wet conditions.

    Science.gov (United States)

    Li, Kai Way; Meng, Fanxing; Zhang, Wei

    2014-01-01

    Solid particles on the floor, both dry and wet, are common but their effects on the friction on the floor were seldom discussed in the literature. In this study, friction measurements were conducted to test the effects of particle size of solid contaminants on the friction coefficient on the floor under footwear, floor, and surface conditions. The results supported the hypothesis that particle size of solids affected the friction coefficient and the effects depended on footwear, floor, and surface conditions. On dry surfaces, solid particles resulted in friction loss when the Neolite footwear pad was used. On the other hand, solid particles provided additional friction when measured with the ethylene vinyl acetate (EVA) footwear pad. On wet surfaces, introducing solid particles made the floors more slip-resistant and such effects depended on particle size. This study provides information for better understanding of the mechanism of slipping when solid contaminants are present.

  15. Importance of baseline specification in evaluating conservation interventions and achieving no net loss of biodiversity.

    Science.gov (United States)

    Bull, J W; Gordon, A; Law, E A; Suttle, K B; Milner-Gulland, E J

    2014-06-01

    There is an urgent need to improve the evaluation of conservation interventions. This requires specifying an objective and a frame of reference from which to measure performance. Reference frames can be baselines (i.e., known biodiversity at a fixed point in history) or counterfactuals (i.e., a scenario that would have occurred without the intervention). Biodiversity offsets are interventions with the objective of no net loss of biodiversity (NNL). We used biodiversity offsets to analyze the effects of the choice of reference frame on whether interventions met stated objectives. We developed 2 models to investigate the implications of setting different frames of reference in regions subject to various biodiversity trends and anthropogenic impacts. First, a general analytic model evaluated offsets against a range of baseline and counterfactual specifications. Second, a simulation model then replicated these results with a complex real world case study: native grassland offsets in Melbourne, Australia. Both models showed that achieving NNL depended upon the interaction between reference frame and background biodiversity trends. With a baseline, offsets were less likely to achieve NNL where biodiversity was decreasing than where biodiversity was stable or increasing. With a no-development counterfactual, however, NNL was achievable only where biodiversity was declining. Otherwise, preventing development was better for biodiversity. Uncertainty about compliance was a stronger determinant of success than uncertainty in underlying biodiversity trends. When only development and offset locations were considered, offsets sometimes resulted in NNL, but not across an entire region. Choice of reference frame determined feasibility and effort required to attain objectives when designing and evaluating biodiversity offset schemes. We argue the choice is thus of fundamental importance for conservation policy. Our results shed light on situations in which biodiversity offsets may

  16. Tribological characterization of the drill collars and casing friction couples

    Science.gov (United States)

    Ripeanu, R. G.; Badicioiu, M.; Caltaru, M.; Dinita, A.; Laudacescu, E.

    2018-01-01

    Drill collars are special pipes used in the drilling of wells for weighting the drill bit, enabling it to drill through the rock. In the drilling process, the drill collars are exposed to an intensive wear due to friction on inner surface of casing wall. In order to evaluate the tribological behaviour of this friction couple, paper presents the drill collars parent material, reconditioned and casing pipe chemical composition, microstructures, hardness and friction tests. For friction tests were prepared samples extracted from new and reconditioned drill collars and from casing pipes and tested on a universal tribometer. Were used plane-on-disk surface friction couples and tests were conducted at two sliding speeds and three normal loads for each materials couple. Plane static partner samples were extracted from casing pipes and disks samples were extracted from new and reconditioned drill collars. Were obtained friction coefficients values and also the temperatures increasing values due to friction working tests parameters. The temperature increasing values were obtained by measuring it with an infrared thermographic camera.

  17. Evaluation of existing EPRI and INEL test data to determine the worm to worm gear coefficient of friction in Limitorque actuators

    Energy Technology Data Exchange (ETDEWEB)

    Garza, I.A.

    1996-12-01

    About the last sizing parameter for motor operated valves which has not been determined by utility or NRC sponsored testing is actuator efficiency. A by-product of EPRI testing for valve factors is the measurement of the actuator efficiencies. Motor sizing in this testing provides efficiency testing for motors running near synchronous speed. INEL testing, sponsored by the NRC, for stem factors and rate of loading provides complimentary data for motors loaded down to zero speed. This paper analyzes the data from these two test programs to determine the coefficient of friction for the worm to worm gear interface. This allowed the development of an algorithm for determining the efficiency of actuators which have not been tested. This paper compares the results of this algorithm to the test data to provide a measure of the accuracy of this method for calculating actuator efficiency.

  18. Evaluation of existing EPRI and INEL test data to determine the worm to worm gear coefficient of friction in Limitorque actuators

    International Nuclear Information System (INIS)

    Garza, I.A.

    1996-01-01

    About the last sizing parameter for motor operated valves which has not been determined by utility or NRC sponsored testing is actuator efficiency. A by-product of EPRI testing for valve factors is the measurement of the actuator efficiencies. Motor sizing in this testing provides efficiency testing for motors running near synchronous speed. INEL testing, sponsored by the NRC, for stem factors and rate of loading provides complimentary data for motors loaded down to zero speed. This paper analyzes the data from these two test programs to determine the coefficient of friction for the worm to worm gear interface. This allowed the development of an algorithm for determining the efficiency of actuators which have not been tested. This paper compares the results of this algorithm to the test data to provide a measure of the accuracy of this method for calculating actuator efficiency

  19. Friction Stir Welding of Al-B4C Composite Fabricated by Accumulative Roll Bonding: Evaluation of Microstructure and Mechanical Behavior

    Science.gov (United States)

    Moradi Faradonbeh, Alireza; Shamanian, Morteza; Edris, Hossein; Paidar, Moslem; Bozkurt, Yahya

    2018-02-01

    In this investigation, friction stir welding (FSW) of Al-B4C composite fabricated by 10 cycles accumulative roll bonding was conducted. In order to investigate the influences of pin geometry on microstructure and mechanical properties, four different pin geometries (cylindrical, square, triangular and hexagonal) were selected. It was found that FSW parameters had a major effect on the fragmentation and distribution of reinforcement particles in stir zone. When the tool travel speed was increased, the distribution of B4C particles was become gradually uniform in the aluminum matrix. The effect of tool rotational speed on the peak temperature was determined to be greater than the tool travel speed. The attained data of tensile properties and microhardness tests showed that the tool travel speed had bilateral effect on the tensile strength. The maximum tensile joint efficiency was obtained as 238% for FSWed of Al-2%B4C composite to annealed base Al sheet.

  20. Effect of friction on the slide guide in an elevator system

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X-g; Li, H-g; Meng, G [State Key Laboratory of Mechanical System and Vibration, Shanghai Jiaotong University, Shanghai 200240 (China)], E-mail: xingang.zhang@gmail.com

    2008-02-15

    The slide guide in an elevator moves in contact against the guide rail. This kind of surface contact exhibits a highly non-linear hysteretic friction behaviour which hampers greatly the riding quality of the elevator system. This paper presents an experimental investigation on this type of phenomenon through measuring the contact friction force between the interface of the slide guide and the rail under different combination of input parameters. The experiment shows frictional behaviours including pre-sliding/gross-sliding regimes, transition behaviour between them, time lag, and velocity (weakening and strengthening) dependence. In addition, it is found that different materials in contact, lubrications and friction duration have strong impacts on evaluation of the friction characteristics. The observations in the test provide an insight into relationships between different friction behaviours and can be used to validate the appropriate theoretical friction models.

  1. FEM simulation of friction testing method based on combined forward rod-backward can extrusion

    DEFF Research Database (Denmark)

    Nakamura, T; Bay, Niels; Zhang, Z. L

    1997-01-01

    A new friction testing method by combined forward rod-backward can extrusion is proposed in order to evaluate frictional characteristics of lubricants in forging processes. By this method the friction coefficient mu and the friction factor m can be estimated along the container wall and the conical...... curves are obtained by rigid-plastic FEM simulations in a combined forward rod-backward can extrusion process for a reduction in area R-b = 25, 50 and 70 percent in the backward can extrusion. It is confirmed that the friction factor m(p) on the punch nose in the backward cart extrusion has almost...... in a mechanical press with aluminium alloy A6061 as the workpiece material and different kinds of lubricants. They confirm the analysis resulting in reasonable values for the friction coefficient and the friction factor....

  2. Precise Measurement of Velocity Dependent Friction in Rotational Motion

    Science.gov (United States)

    Alam, Junaid; Hassan, Hafsa; Shamim, Sohaib; Mahmood, Waqas; Anwar, Muhammad Sabieh

    2011-01-01

    Frictional losses are experimentally determined for a uniform circular disc exhibiting rotational motion. The clockwise and anticlockwise rotations of the disc, that result when a hanger tied to a thread is released from a certain height, give rise to vertical oscillations of the hanger as the thread winds and unwinds over a pulley attached to the…

  3. Evaluation of Adaptive Noise Management Technologies for School-Age Children with Hearing Loss.

    Science.gov (United States)

    Wolfe, Jace; Duke, Mila; Schafer, Erin; Jones, Christine; Rakita, Lori

    2017-05-01

    Children with hearing loss experience significant difficulty understanding speech in noisy and reverberant situations. Adaptive noise management technologies, such as fully adaptive directional microphones and digital noise reduction, have the potential to improve communication in noise for children with hearing aids. However, there are no published studies evaluating the potential benefits children receive from the use of adaptive noise management technologies in simulated real-world environments as well as in daily situations. The objective of this study was to compare speech recognition, speech intelligibility ratings (SIRs), and sound preferences of children using hearing aids equipped with and without adaptive noise management technologies. A single-group, repeated measures design was used to evaluate performance differences obtained in four simulated environments. In each simulated environment, participants were tested in a basic listening program with minimal noise management features, a manual program designed for that scene, and the hearing instruments' adaptive operating system that steered hearing instrument parameterization based on the characteristics of the environment. Twelve children with mild to moderately severe sensorineural hearing loss. Speech recognition and SIRs were evaluated in three hearing aid programs with and without noise management technologies across two different test sessions and various listening environments. Also, the participants' perceptual hearing performance in daily real-world listening situations with two of the hearing aid programs was evaluated during a four- to six-week field trial that took place between the two laboratory sessions. On average, the use of adaptive noise management technology improved sentence recognition in noise for speech presented in front of the participant but resulted in a decrement in performance for signals arriving from behind when the participant was facing forward. However, the improvement

  4. Evaluation of an audiological rehabilitation program for spouses of people with hearing loss.

    Science.gov (United States)

    Preminger, Jill E; Meeks, Suzanne

    2010-05-01

    Since the psychosocial effects of hearing loss are different in the spouse (SP) than in the person with hearing loss (PHL), it seems reasonable that rehabilitation programs designed for PHLs may need to be adapted to benefit SPs. To evaluate the effectiveness of training in communication strategies and psychosocial exercises for SPs of PHLs by determining whether SPs who completed the group class had improved mood, reduced stress, improved marital communication, and greater awareness of their partners' hearing loss-related quality of life (HL-QOL) in comparison with SPs who did not participate in a group class. Additionally, to determine whether PHLs of SPs who participated in a group audiological rehabilitation (AR) class had significantly improved mood, reduced stress, improved marital communication, and better HL-QOL scores in comparison with PHLs whose SPs did not participate in a group class. A randomized controlled study. A total of 72 individuals participated in the study, 36 PHLs and 36 SPs. The PHLs were hearing aid users or cochlear implant users; the SPs had normal or near normal hearing. PHLs in the control group participated in a traditional group AR program while their SPs received no treatment. PHLs in the experimental group also participated in a traditional group AR program while their SPs participated in a treatment program designed for SPs of PHLs. Classes consisted of 90 min sessions meeting once a week for four weeks. All participants completed questionnaires measuring HL-QOL (the SPs filled out third-party reports of HL-QOL), stress, mood (positive affect and negative affect), and communication in the marriage. Scales were completed three times: prior to the AR program, within two weeks after completing the AR program, and 6 mo later. SP awareness of their PHL's HL-QOL was measured by comparing preclass and 6 mo scores with reported critical difference values. Preclass, postclass and 6 mo data were examined with repeated measures ANOVAs. All

  5. Coefficient of Friction Patterns Can Identify Damage in Native and Engineered Cartilage Subjected to Frictional-Shear Stress

    Science.gov (United States)

    Whitney, G. A.; Mansour, J. M.; Dennis, J. E.

    2015-01-01

    The mechanical loading environment encountered by articular cartilage in situ makes frictional-shear testing an invaluable technique for assessing engineered cartilage. Despite the important information that is gained from this testing, it remains under-utilized, especially for determining damage behavior. Currently, extensive visual inspection is required to assess damage; this is cumbersome and subjective. Tools to simplify, automate, and remove subjectivity from the analysis may increase the accessibility and usefulness of frictional-shear testing as an evaluation method. The objective of this study was to determine if the friction signal could be used to detect damage that occurred during the testing. This study proceeded in two phases: first, a simplified model of biphasic lubrication that does not require knowledge of interstitial fluid pressure was developed. In the second phase, frictional-shear tests were performed on 74 cartilage samples, and the simplified model was used to extract characteristic features from the friction signals. Using support vector machine classifiers, the extracted features were able to detect damage with a median accuracy of approximately 90%. The accuracy remained high even in samples with minimal damage. In conclusion, the friction signal acquired during frictional-shear testing can be used to detect resultant damage to a high level of accuracy. PMID:25691395

  6. Coefficient of Friction Patterns Can Identify Damage in Native and Engineered Cartilage Subjected to Frictional-Shear Stress.

    Science.gov (United States)

    Whitney, G A; Mansour, J M; Dennis, J E

    2015-09-01

    The mechanical loading environment encountered by articular cartilage in situ makes frictional-shear testing an invaluable technique for assessing engineered cartilage. Despite the important information that is gained from this testing, it remains under-utilized, especially for determining damage behavior. Currently, extensive visual inspection is required to assess damage; this is cumbersome and subjective. Tools to simplify, automate, and remove subjectivity from the analysis may increase the accessibility and usefulness of frictional-shear testing as an evaluation method. The objective of this study was to determine if the friction signal could be used to detect damage that occurred during the testing. This study proceeded in two phases: first, a simplified model of biphasic lubrication that does not require knowledge of interstitial fluid pressure was developed. In the second phase, frictional-shear tests were performed on 74 cartilage samples, and the simplified model was used to extract characteristic features from the friction signals. Using support vector machine classifiers, the extracted features were able to detect damage with a median accuracy of approximately 90%. The accuracy remained high even in samples with minimal damage. In conclusion, the friction signal acquired during frictional-shear testing can be used to detect resultant damage to a high level of accuracy.

  7. Evaluation of the outcome of CT and MR imaging in pediatric patients with bilateral sensorineural hearing loss.

    Science.gov (United States)

    van Beeck Calkoen, E A; Merkus, P; Goverts, S T; van de Kamp, J M; Mulder, M F; Sanchez Aliaga, E; Hensen, E F

    2018-05-01

    To evaluate the clinically relevant abnormalities as visualized on CT and MR imaging in children with symmetric and asymmetric bilateral sensorineural hearing loss (SNHL), in relation to age and the severity of hearing loss. Retrospective cohort study. Tertiary referral otology and audiology center. From January 2006 until January 2016, a total of 207 children diagnosed with symmetric and asymmetric bilateral SNHL were included. They underwent CT and/or MR imaging for the evaluation of the etiology of their hearing loss. Radiologic abnormalities associated with SNHL. 302 scans were performed in 207 children (median age of 0.8 years old) with bilateral SNHL. The most frequently identified cause of bilateral SNHL was a malformation of the labyrinth. The combined diagnostic yield of CT and MR imaging was 32%. The diagnostic yield of MR (34%) was considerably higher than that of CT (20%). We found a higher rate of abnormalities in children with profound hearing loss (41%) compared to milder hearing loss (8-29%), and in asymmetric SNHL (52%) compared to symmetric SNHL (30%). Imaging is essential in the etiologic evaluation of children with bilateral SNHL. The highest diagnostic yield is found in children with bilateral asymmetric SNHL or profound SNHL. Based on our findings, MR is the primary imaging modality of choice in the etiological evaluation of children with bilateral SNHL because of its high diagnostic yield. Copyright © 2018. Published by Elsevier B.V.

  8. Evaluating the loss of a LWR spent fuel or plutonium shipping package into the sea

    International Nuclear Information System (INIS)

    Heaberlin, S.W.; Baker, D.A.

    1976-06-01

    As the nations of the world turn to nuclear power for an energy source, commerce in nuclear fuel cycle materials will increase. Some of this commerce will be transported by sea. Such shipments give rise to the possibility of loss of these materials into the sea. This paper discusses the postulated accidental loss of two materials, light water reactor (LWR) spent fuel and plutonium, at sea. The losses considered are that of a single shipping package which is either undamaged or damaged by fire prior to the loss. The containment failure of the package in the sea,

  9. Comparative Evaluation of the Loss and Thermal Performance of Advanced Three Level Inverter Topologies

    DEFF Research Database (Denmark)

    Anthon, Alexander; Zhang, Zhe; Andersen, Michael A. E.

    2016-01-01

    . The first solution directly replaces the 1200V primary Si IGBT switches with lower loss 1200V SiC MOSFETs. The second solution strategically adds 600V CoolMos FET devices to the conventional Si T-Type inverter to reduce the primary commutation losses. Semiconductor loss models, experimentally verified...... on calibrated heat sinks, are used to show that both variations can significantly reduce the semiconductor losses compared to the Si T-Type inverter. The results show that both alternatives are attractive if high efficiencies and reduced thermal stress are major requirements for the converter design....

  10. EVALUATION OF SOIL LOSS IN GUARAÍRA BASIN BY GIS AND REMOTE SENSING BASED MODEL

    Directory of Open Access Journals (Sweden)

    Richarde Marques da Silva

    2007-01-01

    Full Text Available Environmental degradation, and specifically erosion, is a serious and extensive problem in many areas in Brazil. Prediction of runoff and erosion in ungauged basins is one of the most challenging tasks anywhere and it is especially a very difficult one in developing countries where monitoring and continuous measurements of these quantities are carried out in very few basins either due to the costs involved or due to the lack of trained personnel. The erosion processes and land use in the Guaraíra River Experimental Basin, located in Paraíba state, Brazil, are evaluated using remote sensing and a runoff-erosion model. WEPP is a process-based continuous simulation erosion model that can be applied to hillslope profiles and small watersheds. WEPP erosion model have been compared in numerous studies to observed values for soil loss and sediment delivery from cropland plots, forest roads, irrigated lands and small watersheds. A number of different techniques for evaluating WEPP have been used, including one recently developed in which the ability of WEPP to accurately predict soil erosion can be compared to the accuracy of replicated plots to predict soil erosion. WEPP was calibrated with daily rainfall data from five rain gauges for the period of 2003 to 2005. The obtained results showed the susceptible areas to the erosion process within Guaraíra river basin, and that the mean sediment yield could be in the order of 3.0 ton/ha/year (in an area of 5.84 ha.

  11. EVALUATION OF SOIL LOSS IN GUARAÍRA BASIN BY GIS AND REMOTE SENSING BASED MODEL

    Directory of Open Access Journals (Sweden)

    Richarde Marques Silva

    2007-12-01

    Full Text Available Environmental degradation, and specifically erosion, is a serious and extensive problem in many areas in Brazil. Prediction of runoff and erosion in ungauged basins is one of the most challenging tasks anywhere and it is especially a very difficult one in developing countries where monitoring and continuous measurements of these quantities are carried out in very few basins either due to the costs involved or due to the lack of trained personnel. The erosion processes and land use in the Guaraíra River Experimental Basin, located in Paraíba state, Brazil, are evaluated using remote sensing and a runoff-erosion model. WEPP is a process-based continuous simulation erosion model that can be applied to hillslope profiles and small watersheds. WEPP erosion model have been compared in numerous studies to observed values for soil loss and sediment delivery from cropland plots, forest roads, irrigated lands and small watersheds. A number of different techniques for evaluating WEPP have been used, including one recently developed in which the ability of WEPP to accurately predict soil erosion can be compared to the accuracy of replicated plots to predict soil erosion. WEPP was calibrated with daily rainfall data from five rain gauges for the period of 2003 to 2005. The obtained results showed the susceptible areas to the erosion process within Guaraíra river basin, and that the mean sediment yield could be in the order of 3.0 ton/ha/year (in an area of 5.84 ha.

  12. Friction welding of A 6061 aluminum alloy and S45C carbon steel

    Energy Technology Data Exchange (ETDEWEB)

    Shinoda, T. [Nagoya Univ., Furo-cho, Chikusa-ku, Nagoya (Japan); Kawata, S. [Post Graduate Student, Nagoya Univ., Nagoya (Japan)

    2004-07-01

    Many researches for friction welding of aluminum with either carbon steel or stainless steel have been carried out. From those results, it is concluded that the greatest problem is the formation of brittle intermetallic compounds at weld interface. However, it is not clearly demonstrated the effect of friction welding parameters on the formation of intermetallic compounds. This research purposes are to evaluate the formation of intermetallic compounds and to investigate the effect of friction welding parameters on the strength of welded joint. For these purposes, A6061 aluminum alloy and S45C carbon steel were used with a continuous drive vertical friction welding machine. Tensile test results revealed that the maximum tensile strength was achieved at extremely short friction time and high upset. The joint strength reached 92% of the tensile strength of A6061 base metal. Tensile strength of friction welding was increasing with increasing upset pressure when friction time 1sec. However, tensile properties were deteriorated with increasing friction time. It was observed that the amount of formed intermetallic compound was increasing with increasing friction time at weld interface. Partly formed intermetallic compound on weld interface were identified when friction time 1 sec. However, intermetallic compound layer were severely developed with longer friction time at weld interface. It was concluded that intermetallic compound layer deteriorated the tensile properties of weld joints. (orig.)

  13. Frictional Heating with Time-Dependent Specific Power of Friction

    Directory of Open Access Journals (Sweden)

    Topczewska Katarzyna

    2017-06-01

    Full Text Available In this paper analytical solutions of the thermal problems of friction were received. The appropriate boundary-value problems of heat conduction were formulated and solved for a homogeneous semi–space (a brake disc heated on its free surface by frictional heat fluxes with different and time-dependent intensities. Solutions were obtained in dimensionless form using Duhamel's theorem. Based on received solutions, evolution and spatial distribution of the dimensionless temperature were analyzed using numerical methods. The numerical results allowed to determine influence of the time distribution of friction power on the spatio-temporal temperature distribution in brake disc.

  14. Evaluation of family history of permanent hearing loss in childhood as a risk indicator in universal screening.

    Science.gov (United States)

    Valido Quintana, Mercedes; Oviedo Santos, Ángeles; Borkoski Barreiro, Silvia; Santana Rodríguez, Alfredo; Ramos Macías, Ángel

    Sixty percent of prelingual hearing loss is of genetic origin. A family history of permanent childhood hearing loss is a risk factor. The objective of the study is to determine the relationship between this risk factor and hearing loss. We have evaluated clinical and epidemiological characteristics and related nonsyndromic genetic variation. This was a retrospective, descriptive and observational study of newborns between January 2007 and December 2010 with family history as risk factor for hearing loss using transient evoked otoacoustic emissions and auditory brainstem response. A total of 26,717 children were born. Eight hundred and fifty-seven (3.2%) had family history. Fifty-seven(0.21%) failed to pass the second test. A percentage of 29.1 (n=16) had another risk factor, and 17.8% (n=9) had no classical risk factor. No risk factor was related to the hearing loss except heart disease. Seventy-six point four percent had normal hearing and 23.6% hearing loss. The mean of family members with hearing loss was 1.25. On genetic testing, 82.86% of homozygotes was normal, 11.43% heterozygosity in Connexin 26 gene (35delG), 2.86% R143W heterozygosity in the same gene and 2.86% mutant homozygotes (35delG). We found no relationship between hearing loss and mutated allele. The percentage of children with a family history and hearing loss is higher than expected in the general population. The genetic profile requires updating to clarify the relationship between hearing loss and heart disease, family history and the low prevalence in the mutations analyzed. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Otorrinolaringología y Cirugía de Cabeza y Cuello. All rights reserved.

  15. Wave friction factor rediscovered

    Science.gov (United States)

    Le Roux, J. P.

    2012-02-01

    The wave friction factor is commonly expressed as a function of the horizontal water particle semi-excursion ( A wb) at the top of the boundary layer. A wb, in turn, is normally derived from linear wave theory by {{U_{{wb}}/T_{{w}}}}{{2π }} , where U wb is the maximum water particle velocity measured at the top of the boundary layer and T w is the wave period. However, it is shown here that A wb determined in this way deviates drastically from its real value under both linear and non-linear waves. Three equations for smooth, transitional and rough boundary conditions, respectively, are proposed to solve this problem, all three being a function of U wb, T w, and δ, the thickness of the boundary layer. Because these variables can be determined theoretically for any bottom slope and water depth using the deepwater wave conditions, there is no need to physically measure them. Although differing substantially from many modern attempts to define the wave friction factor, the results coincide with equations proposed in the 1960s for either smooth or rough boundary conditions. The findings also confirm that the long-held notion of circular water particle motion down to the bottom in deepwater conditions is erroneous, the motion in fact being circular at the surface and elliptical at depth in both deep and shallow water conditions, with only horizontal motion at the top of the boundary layer. The new equations are incorporated in an updated version (WAVECALC II) of the Excel program published earlier in this journal by Le Roux et al. Geo-Mar Lett 30(5): 549-560, (2010).

  16. 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..

  17. 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.)

  18. Friction behavior and other material properties of nickel-titanium and titanium-molybdenum archwires following electrochemical surface refinement.

    Science.gov (United States)

    Meier, Miriam Julia; Bourauel, Christoph; Roehlike, Jan; Reimann, Susanne; Keilig, Ludger; Braumann, Bert

    2014-07-01

    The aim of this work was to investigate whether electrochemical surface treatment of nickel-titanium (NiTi) and titanium-molybdenum (TiMo) archwires (OptoTherm and BetaTitan; Ortho-Dent Specials, Kisdorf, Germany) reduces friction inside the bracket-archwire complex. We also evaluated further material properties and compared these to untreated wires. The material properties of the surface-treated wires (Optotherm/LoFrix and BetaTitan/LoFrix) were compared to untreated wires made by the same manufacturer (see above) and by another manufacturer (Neo Sentalloy; GAC, Bohemia, NY, USA). We carried out a three-point bending test, leveling test, and friction test using an orthodontic measurement and simulation system (OMSS). In addition, a pure bending test was conducted at a special test station, and scanning electron micrographs were obtained to analyze the various wire types for surface characteristics. Finally, edge beveling and cross-sectional dimensions were assessed. Force losses due to friction were reduced by 10 percentage points (from 36 to 26%) in the NiTi and by 12 percentage points (from 59 to 47%) in the TiMo wire specimens. Most of the other material properties exhibited no significant changes after surface treatment. While the three-point bending tests revealed mildly reduced force levels in the TiMo specimens due to diameter losses of roughly 2%, these force levels remained almost unchanged in the NiTi specimens. Compared to untreated NiTi and TiMo archwire specimens, the surface-treated specimens demonstrated reductions in friction loss by 10 and 12 percentage points, respectively.

  19. Losses evaluation of two-level and three-level PFC topologies based on semiconductor measurements

    NARCIS (Netherlands)

    Vermulst, B.J.D.; Duarte, J.L.

    2014-01-01

    Finding and comparing power losses in power electronics topologies is most commonly done by using IGBT switching losses from datasheets. The method in this paper, however, is an approach using a measurement setup, of which the data are used in MATLAB Simulink in combination with Plexim PLECS. Using

  20. Friction Properties of Surface-Fluorinated Carbon Nanotubes

    Science.gov (United States)

    Wal, R. L. Vander; Miyoshi, K.; Street, K. W.; Tomasek, A. J.; Peng, H.; Liu, Y.; Margrave, J. L.; Khabashesku, V. N.

    2005-01-01

    Surface modification of the tubular or sphere-shaped carbon nanoparticles through chemical treatment, e.g., fluorination, is expected to significantly affect their friction properties. In this study, a direct fluorination of the graphene-built tubular (single-walled carbon nanotubes) structures has been carried out to obtain a series of fluorinated nanotubes (fluoronanotubes) with variable C(n)F (n =2-20) stoichiometries. The friction coefficients for fluoronanotubes, as well as pristine and chemically cut nanotubes, were found to reach values as low as 0.002-0.07, according to evaluation tests run in contact with sapphire in air of about 40% relative humidity on a ball-on-disk tribometer which provided an unidirectional sliding friction motion. These preliminary results demonstrate ultra-low friction properties and show a promise in applications of surface modified nanocarbons as a solid lubricant.

  1. Friction measurement and modelling in forward rod extrusion

    DEFF Research Database (Denmark)

    Tan, Xincai; Bay, Niels; Zhang, Wenqi

    2003-01-01

    Forward extrusion is one of the important processes in bulk metal forming. Friction stress can be estimated from the slope of the load±displacement curve at the steady state after the maximum load in a forward extrusion test. In this paper, forward rod extrusion tests are carried out to determine...... as the lubricant. Friction stresses are obtained from measurements of slopes of extrusion pressure±punch travel curves at the steady state stage. Normal pressures are evaluated by using Mohr’s circle, in which shear ¯ow stresses are estimated at the maximum elastic deformation points from the same extrusion...... pressure±punch travel curves. It is found that the relationship between normal pressure and friction stress appears linear, and therefore Coulomb’s friction model ®ts the experimental data very well. Extrusion pressure±punch travel curves before the steady state can be divided into four stages: elastic...

  2. Importance of Baseline Specification in Evaluating Conservation Interventions and Achieving No Net Loss of Biodiversity

    Science.gov (United States)

    Bull, J W; Gordon, A; Law, E A; Suttle, K B; Milner-Gulland, E J

    2014-01-01

    There is an urgent need to improve the evaluation of conservation interventions. This requires specifying an objective and a frame of reference from which to measure performance. Reference frames can be baselines (i.e., known biodiversity at a fixed point in history) or counterfactuals (i.e., a scenario that would have occurred without the intervention). Biodiversity offsets are interventions with the objective of no net loss of biodiversity (NNL). We used biodiversity offsets to analyze the effects of the choice of reference frame on whether interventions met stated objectives. We developed 2 models to investigate the implications of setting different frames of reference in regions subject to various biodiversity trends and anthropogenic impacts. First, a general analytic model evaluated offsets against a range of baseline and counterfactual specifications. Second, a simulation model then replicated these results with a complex real world case study: native grassland offsets in Melbourne, Australia. Both models showed that achieving NNL depended upon the interaction between reference frame and background biodiversity trends. With a baseline, offsets were less likely to achieve NNL where biodiversity was decreasing than where biodiversity was stable or increasing. With a no-development counterfactual, however, NNL was achievable only where biodiversity was declining. Otherwise, preventing development was better for biodiversity. Uncertainty about compliance was a stronger determinant of success than uncertainty in underlying biodiversity trends. When only development and offset locations were considered, offsets sometimes resulted in NNL, but not across an entire region. Choice of reference frame determined feasibility and effort required to attain objectives when designing and evaluating biodiversity offset schemes. We argue the choice is thus of fundamental importance for conservation policy. Our results shed light on situations in which biodiversity offsets may

  3. The friction control of magnetic fluid in the Couette flow

    Energy Technology Data Exchange (ETDEWEB)

    Labkovich, O.N., E-mail: olji@tut.by; Reks, A.G.; Chernobai, V.A.

    2017-06-01

    In the work characteristic areas of magnetic fluid flow are experimentally determined in the gap between the cylinders: the area of strong dipole-dipole interaction between magnetite particles 041,2. For areas with high flow losses in viscous friction is shown the possibility of reducing the introduction of magnetic fluid of carbon nanotubes and creating a rotating magnetic field. - Highlights: • Typical areas of magnetic fluid flow are determined in the gap. • Influence of dipole-dipole interaction of magnetite particles on the viscous friction. • Features of Taylor vortex flow.

  4. Flow Friction or Spontaneous Ignition?

    Science.gov (United States)

    Stoltzfus, Joel M.; Gallus, Timothy D.; Sparks, Kyle

    2012-01-01

    "Flow friction," a proposed ignition mechanism in oxygen systems, has proved elusive in attempts at experimental verification. In this paper, the literature regarding flow friction is reviewed and the experimental verification attempts are briefly discussed. Another ignition mechanism, a form of spontaneous combustion, is proposed as an explanation for at least some of the fire events that have been attributed to flow friction in the literature. In addition, the results of a failure analysis performed at NASA Johnson Space Center White Sands Test Facility are presented, and the observations indicate that spontaneous combustion was the most likely cause of the fire in this 2000 psig (14 MPa) oxygen-enriched system.

  5. [Friction: self-ligating brackets].

    Science.gov (United States)

    Thermac, Guilhem; Morgon, Laurent; Godeneche, Julien

    2008-12-01

    The manufacturers of self-ligating brackets advertise a reduction of the friction engendered between the wire and the bracket, which is an essential parameter for treatment's speed and comfort. We have compared the friction obtained with four types of self-ligating brackets - In-Ovation R, Damon 3, Smart Clip and Quick - with that of a standard bracket Omniarch associated with an elastomeric ligature. All bracket were tested on a bench of traction with three types of wires: steel .019"x.025", TMA .019"x.025" and NEO sentalloy F300 .020"x.020". The results confirm a clear friction reduction for all tested wire.

  6. Ultra Low Friction of DLC Coating with Lubricant

    International Nuclear Information System (INIS)

    Kano, M; Yoshida, K

    2010-01-01

    The objective of this study was to find a trigger to make clear a mechanism of the ultra low friction by evaluating the friction property of DLC-DLC combination under lubrication with the simple fluid. The Pin-on-disc reciprocating and rotating sliding tests were conducted to evaluate the friction property. The super low friction property of pure sliding with the ta-C(T) pair coated by the filtered arc deposition process under oleic acid lubrication was found at the mixed lubrication condition. It was thought that the low share strength tribofilm composed of water and acid seemed to be formed on ta-C sliding interface. Additionally, the smooth sliding surface formed on ta-C(T) was seemed to be required to keep this tribofilm. Then, the super low friction was thought to be obtained by this superlubrication condition. Although the accurate and direct experimental data must be required to make clear this super low friction mechanism, the advanced effect obtained by the simple material combination is expected to be applied on the large industrial fields in near future.

  7. A catheter friction tester using balance sensor: Combined evaluation of the effects of mechanical properties of tubing materials and surface coatings.

    Science.gov (United States)

    Røn, Troels; Jacobsen, Kristina Pilgaard; Lee, Seunghwan

    2018-04-24

    In this study, we introduce a new experimental approach to characterize the forces emerging from simulated catherization. This setup allows for a linear translation of urinary catheters in vertical direction as controlled by an actuator. By employing silicone-based elastomer with a duct of comparable diameter with catheters as urethra model, sliding contacts during the translation of catheters along the duct is generated. A most unique design and operation feature of this setup is that a digital balance was employed as the sensor to detect emerging forces from simulated catherization. Moreover, the possibility to give a variation in environment (ambient air vs. water), clearance, elasticity, and curvature of silicone-based urethra model allows for the detection of forces arising from diverse simulated catherization conditions. Two types of commercially available catheters varying in tubing materials and surface coatings were tested together with their respective uncoated catheter tubing. The first set of testing on the catheter samples showed that this setup can probe the combined effect from flexural strain of bulk tubing materials and slipperiness of surface coatings, both of which are expected to affect the comfort and smooth gliding in clinical catherization. We argue that this new experimental setup can provide unique and valuable information in preclinical friction testing of urinary catheters. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. Evaluation of levee setbacks for flood-loss reduction, Middle Mississippi River, USA

    Science.gov (United States)

    Dierauer, Jennifer; Pinter, Nicholas; Remo, Jonathan W. F.

    2012-07-01

    SummaryOne-dimensional hydraulic modeling and flood-loss modeling were used to test the effectiveness of levee setbacks for flood-loss reduction along the Middle Mississippi River (MMR). Four levee scenarios were assessed: (1) the present-day levee configuration, (2) a 1000 m levee setback, (3) a 1500 m levee setback, and (4) an optimized setback configuration. Flood losses were estimated using FEMA's Hazus-MH (Hazards US Multi-Hazard) loss-estimation software on a structure-by-structure basis for a range of floods from the 2- to the 500-year events. These flood-loss estimates were combined with a levee-reliability model to calculate probability-weighted damage estimates. In the simplest case, the levee setback scenarios tested here reduced flood losses compared to current conditions for large, infrequent flooding events but increased flood losses for smaller, more frequent flood events. These increases occurred because levee protection was removed for some of the existing structures. When combined with buyouts of unprotected structures, levee setbacks reduced flood losses for all recurrence intervals. The "optimized" levee setback scenario, involving a levee configuration manually planned to protect existing high-value infrastructure, reduced damages with or without buyouts. This research shows that levee setbacks in combination with buyouts are an economically viable approach for flood-risk reduction along the study reach and likely elsewhere where levees are widely employed for flood control. Designing a levee setback around existing high-value infrastructure can maximize the benefit of the setback while simultaneously minimizing the costs. The optimized levee setback scenario analyzed here produced payback periods (costs divided by benefits) of less than 12 years. With many aging levees failing current inspections across the US, and flood losses spiraling up over time, levee setbacks are a viable solution for reducing flood exposure and flood levels.

  9. 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…

  10. 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.

  11. Tools evaluation and development for loss of coolant accidents analysis in research reactors

    International Nuclear Information System (INIS)

    Maprelian, Eduardo; Cabral, Eduardo L.L.; Silva, Antonio T. e

    1999-01-01

    The loss of coolant accidents (LOCA) in pool type research reactors are normally considered as limiting in the licensing process. This paper verifies the viability of the computer code 3D-AIRLOCA to analyze LOCA in a pool type research reactor, and also develops two computer codes LOSS and TEMPLOCA. The computer code LOSS determines the time tom drawn the pool down to the level of the bottom of the core, and the computer code TEMPLOCA calculates the peak fuel element temperature during the transient. These two coders substitutes the 3D-AIRLOCA in the LOCA analysis for pool type research reactors. (author)

  12. Multimodal Friction Ignition Tester

    Science.gov (United States)

    Davis, Eddie; Howard, Bill; Herald, Stephen

    2009-01-01

    The multimodal friction ignition tester (MFIT) is a testbed for experiments on the thermal and mechanical effects of friction on material specimens in pressurized, oxygen-rich atmospheres. In simplest terms, a test involves recording sensory data while rubbing two specimens against each other at a controlled normal force, with either a random stroke or a sinusoidal stroke having controlled amplitude and frequency. The term multimodal in the full name of the apparatus refers to a capability for imposing any combination of widely ranging values of the atmospheric pressure, atmospheric oxygen content, stroke length, stroke frequency, and normal force. The MFIT was designed especially for studying the tendency toward heating and combustion of nonmetallic composite materials and the fretting of metals subjected to dynamic (vibrational) friction forces in the presence of liquid oxygen or pressurized gaseous oxygen test conditions approximating conditions expected to be encountered in proposed composite material oxygen tanks aboard aircraft and spacecraft in flight. The MFIT includes a stainless-steel pressure vessel capable of retaining the required test atmosphere. Mounted atop the vessel is a pneumatic cylinder containing a piston for exerting the specified normal force between the two specimens. Through a shaft seal, the piston shaft extends downward into the vessel. One of the specimens is mounted on a block, denoted the pressure block, at the lower end of the piston shaft. This specimen is pressed down against the other specimen, which is mounted in a recess in another block, denoted the slip block, that can be moved horizontally but not vertically. The slip block is driven in reciprocating horizontal motion by an electrodynamic vibration exciter outside the pressure vessel. The armature of the electrodynamic exciter is connected to the slip block via a horizontal shaft that extends into the pressure vessel via a second shaft seal. The reciprocating horizontal

  13. Friction induced hunting limit cycles : a comparison between the LuGre and switch friction model

    NARCIS (Netherlands)

    Hensen, R.H.A.; Molengraft, van de M.J.G.; Steinbuch, M.

    2003-01-01

    In this paper, friction induced limit cycles are predicted for a simple motion system consisting of a motor-driven inertia subjected to friction and a PID-controlled regulator task. The two friction models used, i.e., (i) the dynamic LuGre friction model and (ii) the static switch friction model,

  14. Evaluation of the current practices of noise-induced hearing loss (NIHL) awareness training in the South African mining industry

    CSIR Research Space (South Africa)

    Edwards, AL

    2015-01-01

    Full Text Available This study aimed to evaluate the current practices in relation to best practice criteria and make recommendations for improvements to noise-induced hearing loss (NIHL) awareness training in the South African mining industry. A survey tool based...

  15. Development of a New Method to Investigate the Dynamic Friction Behavior of Interfaces Using a Kolsky Tension Bar

    International Nuclear Information System (INIS)

    Sanborn, B.; Song, B.; Nishida, E.

    2017-01-01

    In order to understand interfacial interaction of a bi-material during an impact loading event, the dynamic friction coefficient is one of the key parameters that must be characterized and quantified. In this study, a new experimental method to determine the dynamic friction coefficient between two metals was developed by using a Kolsky tension bar and a custom-designed friction fixture. Polyvinylidene fluoride (PVDF) force sensors were used to measure the normal force applied to the friction tribo pairs and the friction force was measured with conventional Kolsky tension bar method. To evaluate the technique, the dynamic friction coefficient between 4340 steel and 7075-T6 aluminum was investigated at an impact speed of approximately 8 m/s. Additionally, the dynamic friction coefficient of the tribo pairs with varied surface roughness was also investigated. The data suggest that higher surface roughness leads to higher friction coefficients at the same speed of 8 m/s.

  16. Generic evaluation of feedwater transients and small break loss-of-coolant accidents in combustion engineering designed operating plants

    International Nuclear Information System (INIS)

    1980-01-01

    The purpose of this report is to summarize the results of a generic evaluation of feedwater transients, small break loss-of-coolant accidents (LOCAs), and other TMI-2-related events in the Combustion Engineering (CE)-designed operating plants and to establish or confirm the bases for their continued operation. The results of this evaluation are presented in this report in the form of a set of findings and recommendations in each of the principal review areas

  17. Rubber friction and tire dynamics

    International Nuclear Information System (INIS)

    Persson, B N J

    2011-01-01

    We propose a simple rubber friction law, which can be used, for example, in models of tire (and vehicle) dynamics. The friction law is tested by comparing numerical results to the full rubber friction theory (Persson 2006 J. Phys.: Condens. Matter 18 7789). Good agreement is found between the two theories. We describe a two-dimensional (2D) tire model which combines the rubber friction model with a simple mass-spring description of the tire body. The tire model is very flexible and can be used to accurately calculate μ-slip curves (and the self-aligning torque) for braking and cornering or combined motion (e.g. braking during cornering). We present numerical results which illustrate the theory. Simulations of anti-blocking system (ABS) braking are performed using two simple control algorithms.

  18. 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.

  19. Rubber friction and tire dynamics.

    Science.gov (United States)

    Persson, B N J

    2011-01-12

    We propose a simple rubber friction law, which can be used, for example, in models of tire (and vehicle) dynamics. The friction law is tested by comparing numerical results to the full rubber friction theory (Persson 2006 J. Phys.: Condens. Matter 18 7789). Good agreement is found between the two theories. We describe a two-dimensional (2D) tire model which combines the rubber friction model with a simple mass-spring description of the tire body. The tire model is very flexible and can be used to accurately calculate μ-slip curves (and the self-aligning torque) for braking and cornering or combined motion (e.g. braking during cornering). We present numerical results which illustrate the theory. Simulations of anti-blocking system (ABS) braking are performed using two simple control algorithms.

  20. Hearing loss in the developing world: Evaluating the iPhone mobile ...

    African Journals Online (AJOL)

    groups include the elderly and patients receiving potentially ototoxic medications: ... risk of developing high-frequency hearing loss, as explained below. High-risk groups .... wax impaction. Infection control was maintained during testing. All.

  1. Novel method of evaluating miners at risk for noise-induced hearing loss

    CSIR Research Space (South Africa)

    Edwards, AL

    2010-08-31

    Full Text Available Noise-induced hearing loss (NIHL) negatively affects the quality of life of mine employees and costs mining companies large amounts in compensation claims. The prevention of NIHL requires early identification and recent evidence about the ability...

  2. Investigation of friction characteristics in segmented piston ring liner assembly of IC engine

    Directory of Open Access Journals (Sweden)

    Tejaskumar Chaudhari

    2016-09-01

    Full Text Available The friction at the piston ring cylinder liner assembly (PRLA is a major contributor in the total friction losses in the I.C. engine. New materials, coatings and high-tech machining processes that previously were considered to be too expensive and therefore only used in complex applications are today becoming more affordable. A significant amount of the total power loss in a modern automotive engine is due to the Friction interaction between the top compression ring and the cylinder liner, especially at the TDC and BDC where boundary lubrication exists. The change in piston speed is accompanied with change the lubrication regime in the cylinder, which results change in friction between the ring and the liner during the entire stroke of the piston. Theoretical modelling of friction force from the various sources of friction will be compared to experimental results for analysing the tribological characteristics. The appropriate sample of piston ring and cylinder liner pair is developed for studying the different tribological parameters on Reciprocating Tribometer. The variable parameters are engine speed, oil viscosity, and load. The experimental results and observations are studied under different operating conditions in speed ranges from 300 rpm to 1500 rpm with constant load of 60 N. It can be seen that as speed increases, the friction force and friction coefficient also decreases.

  3. [An evaluation of the economic loss from intestinal helminthiases in the Uzbek SSR].

    Science.gov (United States)

    Abdiev, T A; Zubitskaia, M A; Kovalenko, A F; Fuzaĭlov, Iu M; Baratov, R D; Ziganshina, N Kh; Isaeva, Kh B; Borukhov, S M; Priezzhaeva, N G; Musaeva, G A

    1990-01-01

    Calculations of economic loss costs due to procedures for helminth detection and the out-patient treatment of recognized cases of enterobiasis, hymenolepiasis, taeniasis, ascariasis, trichocephaliasis in the Uzbek SSR in 1985 were made as were the costs of inpatient treatment in the specialized clinics in 1986 with account for the loss due to the related decrease in the national output and payments for disability. Their total turned to be about 1.8 million rubles.

  4. Evaluation of human dental loss caused by carbamide peroxide bleacher compared with phosphoric acid conditioning - radioactive method

    International Nuclear Information System (INIS)

    Adachi, Eduardo Makoto; Yousseff, Michel Nicolau; Saiki, Mitiko

    2002-01-01

    The radiometric method was applied to the evaluation of dental loss caused by carbamide peroxide when it is applied on the surface layers of enamel and dentin tissues. Also the dental loss caused by the etching with 37% phosphoric acid procedure used in aesthetic restoration was assessed for comparison with those results obtained. The tooth samples irradiated with a P standard in a thermal neutron flux of the nuclear reactor were placed in contact with 10% carbamide peroxide or with 37% phosphoric acid solution. The radioactivity of 32 P transferred from the radioactive teeth to the bleaching gel or to etching acid was measured using a Geiger Muller detector to calculate the mass of P removed in this treatment and losses were calculated after obtaining their P concentrations. Results obtained indicated that enamel and dentin exposed to carbamide peroxide bleaching agent lose phosphorus. The extent of enamel loss was smaller than that obtained for dentin. In the case of acid etching, there was no difference between the results obtained for enamel and dentin loss. Also the dentin loss obtained after a treatment of 30 applications of 10% carbamide peroxide was the same magnitude of that one application of 37% phosphoric acid. (author)

  5. Friction and wear performance of low-friction carbon coatings under oil lubrication

    International Nuclear Information System (INIS)

    Kovalchenko, A.; Ajayi, O. O.; Erdemir, A.; Fenske, G. R.

    2001-01-01

    Amorphous carbon coatings with very low friction properties were recently developed at Argonne National Laboratory. These coatings have shown good promise in mitigating excessive wear and scuffing problems associated with low-lubricity diesel fuels. To reduce the negative effect of sulfur and other lubricant additives in poisoning the after-treatment catalyst, a lubricant formulation with a low level of sulfur may be needed. Exclusion of proven sulfur-containing extreme pressure (EP) and antiwear additives from oils will require other measures to ensure durability of critical lubricated components. The low-friction carbon coating has the potential for such applications. In the present study, we evaluated the friction and wear attributes of three variations of the coating under a boundary lubrication regime. Tests were conducted with both synthetic and mineral oil lubricants using a ball-on-flat contact configuration in reciprocating sliding. Although the three variations of the coating provided modest reductions in friction coefficient, they all reduced wear substantially compared to an uncoated surface. The degradation mode of oxidative wear on the uncoated surface was replaced by a polishing wear mode on the coated surfaces

  6. Nuclear friction and chaotic motion

    International Nuclear Information System (INIS)

    Srokowski, T.; Szczurek, A.; Drozdz, S.

    1990-01-01

    The concept of nuclear friction is considered from the point of view of regular versus chaotic motion in an atomic nucleus. Using a realistic nuclear Hamiltonian it is explicitly shown that the frictional description of the gross features of nuclear collisions is adequate if the system behaves chaotically. Because of the core in the Hamiltonian, the three-body nuclear system already reveals a structure of the phase space rich enough for this concept to be applicable

  7. Slipforming - Materials effect on friction

    OpenAIRE

    Busterud, Jørgen Thomasgaard

    2016-01-01

    Master's thesis in Structural engineering Slipforming is a construction method for concrete and it is especially suited for tall constructions with simple geometry. This method have occasionally caused lifting cracks and other surface damages, due to the friction between the slipform panel and the concrete has become to high. The thesis will look at how the choice of material composition in concrete mixes in the combination of a given slipform rate would affect the friction between the ...

  8. Slow rupture of frictional interfaces

    OpenAIRE

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

    2011-01-01

    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 comple...

  9. 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...... theory. More concretely I find the dominate optimization friction to be individuals’ inattention about their earnings during the year, while real adjustment cost and gradual learning appears to be of less importance....

  10. Evaluation of seasonality on total water intake, water loss and water balance in the general population in Greece.

    Science.gov (United States)

    Malisova, O; Bountziouka, V; Panagiotakos, D Β; Zampelas, A; Kapsokefalou, M

    2013-07-01

    Water balance is achieved when water intake from solid and fluid foods and drinking water meets water losses, mainly in sweat, urine and faeces. Seasonality, particularly in Mediterranean countries that have a hot summer, may affect water loss and consequently water balance. Water balance has not been estimated before on a population level and the effect of seasonality has not been evaluated. The present study aimed to compare water balance, intake and loss in summer and winter in a sample of the general population in Greece. The Water Balance Questionnaire (WBQ) was used to evaluate water balance, estimating water intake and loss in summer (n = 480) and in winter (n = 412) on a stratified sample of the general population in Athens, Greece. In winter, mean (SD) water balance was -63 (1478) mL/day(-1) , mean (SD)water intake was 2892 (987) mL/day(-1) and mean (quartile range) water loss was 2637 (1810-3922) mL/day(-1) . In summer, mean (SD) water balance was -58 (2150) mL/day(-1) , mean (SD) water intake was 3875 (1373) mL/day(-1) and mean (quartile range) water loss was 3635 (2365-5258) mL/day(-1) . Water balance did not differ between summer and winter (P = 0.96); however, the data distribution was different; in summer, approximately 8% more participants were falling in the low and high water balance categories. Differences in water intake from different sources were identified (P balance in summer and winter was not different. However, water intake and loss were approximately 40% higher in summer than in winter. More people were falling in the low and high water balance categories in summer when comparing the distribution on water balance in winter. © 2013 The Authors Journal of Human Nutrition and Dietetics © 2013 The British Dietetic Association Ltd.

  11. Static and Dynamic Friction Behavior of Candidate High Temperature Airframe Seal Materials

    Science.gov (United States)

    Dellacorte, C.; Lukaszewicz, V.; Morris, D. E.; Steinetz, B. M.

    1994-01-01

    The following report describes a series of research tests to evaluate candidate high temperature materials for static to moderately dynamic hypersonic airframe seals. Pin-on-disk reciprocating sliding tests were conducted from 25 to 843 C in air and hydrogen containing inert atmospheres. Friction, both dynamic and static, was monitored and serves as the primary test measurement. In general, soft coatings lead to excessive static friction and temperature affected friction in air environments only.

  12. Pressure drop and friction factor correlations of supercritical flow

    International Nuclear Information System (INIS)

    Fang Xiande; Xu Yu; Su Xianghui; Shi Rongrong

    2012-01-01

    Highlights: ► Survey and evaluation of friction factor models for supercritical flow. ► Survey of experimental study of supercritical flow. ► New correlation of friction factor for supercritical flow. - Abstract: The determination of the in-tube friction pressure drop under supercritical conditions is important to the design, analysis and simulation of transcritical cycles of air conditioning and heat pump systems, nuclear reactor cooling systems and some other systems. A number of correlations for supercritical friction factors have been proposed. Their accuracy and applicability should be examined. This paper provides a comprehensive survey of experimental investigations into the pressure drop of supercritical flow in the past decade and a comparative study of supercritical friction factor correlations. Our analysis shows that none of the existing correlations is completely satisfactory, that there are contradictions between the existing experimental results and thus more elaborate experiments are needed, and that the tube roughness should be considered. A new friction factor correlation for supercritical tube flow is proposed based on 390 experimental data from the available literature, including 263 data of supercritical R410A cooling, 45 data of supercritical R404A cooling, 64 data of supercritical carbon dioxide (CO 2 ) cooling and 18 data of supercritical R22 heating. Compared with the best existing model, the new correlation increases the accuracy by more than 10%.

  13. Friction weld ductility and toughness as influenced by inclusion morphology

    International Nuclear Information System (INIS)

    Eberhard, B.J.; Schaaf, B.W. Jr.; Wilson, A.D.

    1983-01-01

    Friction welding consistently provides high strength, freedom from fusion defects, and high productivity. However, friction welds in carbon steel exhibit impact toughness and bend ductility that are significantly lower than that of the base metal. The inclusion content and morphology were suspected to be major contributors to the reduction in weld ductility. For this reason, four electric furnace steels - three types of ASTM A516 Grade 70, and an ASTM A737 Grade B steel - were investigated. Friction welds were made by both the inertia and direct drive process variations and the welds evaluated. It was shown that friction welds of inclusion-controlled steels exhibited much improved toughness and bend ductility were demonstrated. Upper shelf impact energy was equivalent to or greater than that of the base metal in the short transverse direction. The transition temperature range for all four materials was shifted to higher temperatures for both types of friction welds. Under the conditions of this test, the direct drive friction welds showed a greater shift than the inertia friction welds. The ductility and toughness of welds in A737 Grade B steel were superior to welds in A516 Grade 70 steels, reflecting the superior properties of the base metal. Welds of the A737 material had usable Charpy V-notch impact toughness of 20 to 30 ft-lb (27 to 41 J) at temperatures as low as -40 0 F (-40 0 C). All the welds had an acicular structure. The differences in properties between the inertia and direct drive friction welds appear associated with microstructural variations. These variations resulted from the different heat inputs and cooling rates of the two process variations were demonstrated. The beneficial effects of inclusion control on toughness and ductility. In addition, it also indicates that additional improvements may be attainable through control of the as-welded microstructure by process manipulation

  14. Application of acoustic emission technique and friction welding for excavator hose nipple

    International Nuclear Information System (INIS)

    Kong, Yu Sik; Lee, Jin Kyung

    2013-01-01

    Friction welding is a very useful joining process to weld metals which have axially symmetric cross section. In this paper, the feasibility of industry application was determined by analyzing the mechanical properties of weld region for a specimen of tube-to-tube shape for excavator hose nipple with friction welding, and optimized welding variables were suggested. In order to accomplish this object, friction heating pressure and friction heating time were selected as the major process variables and the experiment was performed in three levels of each parameter. An acoustic emission(AE) technique was applied to evaluate the optimal friction welding conditions nondestructively. AE parameters of accumulative count and event were analyzed in terms of generating trend of AE signals across the full range of friction weld. The typical waveform and frequency spectrum of AE signals which is generated by friction weld were discussed. From this study the optimal welding variables could be suggested as rotating speed of 1300 rpm, friction heating pressure of 15 MPa, and friction heating time of 10 sec. AE event was a useful parameter to estimate the tensile strength of tube-to tube specimen with friction weld.

  15. Frequency-dependent solvent friction and torsional damping in liquid 1,2-difluoroethane

    Science.gov (United States)

    MacPhail, Richard A.; Monroe, Frances C.

    1991-04-01

    We have used Raman spectroscopy to study the torsional dynamics, rotational dynamics, and conformational solvation energy of liquid 1,2-difluoroethane. From the Raman intensities, we obtain Δ H(g-t) = -2.4±0.1 kcal/mol, indicating strong dipolar solvation of the gauche conformer. We analyze the Raman linewidths of the CCF bending bands to obtain the zero-frequency torsional damping coefficient or well friction for the gauche conformer, and from the linewidth of the torsion band we obtain the friction evaluated at the torsional frequency. The zero-frequency well friction shows deviations from hydrodynamic behavior reminiscent of those observed for barrier friction, whereas the high-frequency friction is considerably smaller in magnitude and independent of temperature and viscosity. The zero-frequency torsional friction correlates linearly with the rotational friction. It is argued that the small amplitude of the torsional fluctuations emphasizes the short distance, or high wavevector components of the solvent friction. Dielectric friction apparently does not contribute to the torsional friction at the observed frequencies.

  16. Effect of friction on pebble flow pattern in pebble bed reactor

    International Nuclear Information System (INIS)

    Li, Yu; Gui, Nan; Yang, Xingtuan; Tu, Jiyuan; Jiang, Shengyao

    2016-01-01

    Highlights: • A 3D DEM study on particle–wall/particle friction in pebble bed reactor is carried out. • Characteristic values are defined to evaluate features of pebble flow pattern quantitatively. • Particle–wall friction is dominant to determine flow pattern in a specific pebble bed. • Friction effect of hopper part on flow field is more critical than that of cylinder part. • Three cases of 1:1 full scale practical pebble beds are simulated for demonstration. - Abstract: Friction affects pebble flow pattern in pebble-bed high temperature gas-cooled reactor (HTGR) significantly. Through a series of three dimensional DEM (discrete element method) simulations it is shown that reducing friction can be beneficial and create a uniform and consistent flow field required by nuclear engineering. Particle–wall friction poses a decisive impact on flow pattern, and particle–particle friction usually plays a secondary role; relation between particle–wall friction and flow pattern transition is also concluded. Moreover, new criteria are created to describe flow patterns quantitatively according to crucial issues in HTGR like stagnant zone, radial uniformity and flow sequence. Last but not least, it is proved that friction control of hopper part is more important than that of cylinder part in practical pebble beds, so reducing friction between pebbles and hopper surface is the engineering priority.

  17. Evaluation of aquifer heterogeneity effects on river flow loss using a transition probability framework

    Science.gov (United States)

    Engdahl, N.B.; Vogler, E.T.; Weissmann, G.S.

    2010-01-01

    River-aquifer exchange is considered within a transition probability framework along the Rio Grande in Albuquerque, New Mexico, to provide a stochastic estimate of aquifer heterogeneity and river loss. Six plausible hydrofacies configurations were determined using categorized drill core and wetland survey data processed through the TPROGS geostatistical package. A base case homogeneous model was also constructed for comparison. River loss was simulated for low, moderate, and high Rio Grande stages and several different riverside drain stage configurations. Heterogeneity effects were quantified by determining the mean and variance of the K field for each realization compared to the root-mean-square (RMS) error of the observed groundwater head data. Simulation results showed that the heterogeneous models produced smaller estimates of loss than the homogeneous approximation. Differences between heterogeneous and homogeneous model results indicate that the use of a homogeneous K in a regional-scale model may result in an overestimation of loss but comparable RMS error. We find that the simulated river loss is dependent on the aquifer structure and is most sensitive to the volumetric proportion of fines within the river channel. Copyright 2010 by the American Geophysical Union.

  18. Evaluation of the correlations for predicting evaporative loss from water body

    International Nuclear Information System (INIS)

    Yilmaz, T.P.; Aybar, H.S.

    1999-01-01

    Water evaporation (evaporation from here on) is a natural phenomenon that is important for system design and system safety in many engineering branches. Indeed, evaporative heat and mass loss are observed and calculated in very diverse situations, such as irrigation plants, water purification plants, cooling ponds, lakes, dams, swimming pools, health spas, management of liquid wastes as in evaporation pools, and spent fuel pools in nuclear power plants. There are a number of correlations obtained from experimental studies that predict the evaporative heat and mass loss from a water body. This study aims to summarize and to compare the existing evaporation correlations to determine the upper and lower bounding correlations for use in various thermal-hydraulic analyses of systems. Currently and widely used, six correlations found in the literature have been selected and tested using the major parameters of evaporation such as water temperature, air relative humidity, air velocity, and temperature. The comparison test cases show that ASHRAE (1991) and Ryan et al. (1974) equations result in the highest evaporative loss, while the Brady et al. (1969) equation provides the lowest evaporative loss in most conditions. Engineering designers may sometimes need the upper bound value of evaporative loss or sometimes the lower bound value for a conservative calculation. The authors conclude that using a single equation does not provide the conservative calculation for every situation and show which correlation gives the lower or upper bound for different conditions

  19. Factor value determination and applicability evaluation of universal soil loss equation in granite gneiss region

    Directory of Open Access Journals (Sweden)

    Wen-hai Zhang

    2009-06-01

    Full Text Available Six types of runoff plots were set up and an experimental study was carried out to examine natural rate of soil and water loss in the granite gneiss region of northern Jiangsu Province in China. Through correlation analysis of runoff and soil loss during 364 rainfall events, a simplified and convenient mathematical formula suitable for calculating the rainfall erosivity factor (R for the local region was established. Other factors of the universal soil loss equation (USLE model were also determined. Relative error analysis of the soil loss of various plots calculated by the USLE model on the basis of the observed values showed that the relative error ranged from -3.5% to 9.9% and the confidence level was more than 90%. In addition, the relative error was 5.64% for the terraced field and 12.36% for the sloping field in the practical application. Thus, the confidence level was above 87.64%. These results provide a scientific basis for forecasting and monitoring soil and water loss, for comprehensive management of small watersheds, and for soil and water conservation planning in the region.

  20. Evaluation of Core Loss in Magnetic Materials Employed in Utility Grid AC Filters

    DEFF Research Database (Denmark)

    Beres, Remus Narcis; Wang, Xiongfei; Blaabjerg, Frede

    2016-01-01

    magnetic materials adopted in utility grid ac filters have been investigated and measured for both sinusoidal and rectangular excitation, with and without dc bias condition. The core loss information can ensure cost effective passive filter designs and may avoid trial-error design procedures of the passive......Inductive components play an important role in filtering the switching harmonics related to the pulse width modulation in voltage source converters. Particularly, the filter reactor on the converter side of the filter is subjected to rectangular excitation which may lead to significant losses...... in the core, depending on the magnetic material of choice and current ripple specifications. Additionally, shunt or series reactors that exists in LCL or trap filters and which are subjected to sinusoidal excitations have different specifications and requirements. Therefore, the core losses of different...

  1. LOW-ENGINE-FRICTION TECHNOLOGY FOR ADVANCED NATURAL-GAS RECIPROCATING ENGINES

    Energy Technology Data Exchange (ETDEWEB)

    Victor Wong; Tian Tian; Luke Moughon; Rosalind Takata; Jeffrey Jocsak

    2006-03-31

    This program aims at improving the efficiency of advanced natural-gas reciprocating engines (ANGRE) by reducing piston and piston ring assembly friction without major adverse effects on engine performance, such as increased oil consumption and wear. An iterative process of simulation, experimentation and analysis is being followed towards achieving the goal of demonstrating a complete optimized low-friction engine system. To date, a detailed set of piston and piston-ring dynamic and friction models have been developed and applied that illustrate the fundamental relationships among mechanical, surface/material and lubricant design parameters and friction losses. Demonstration of low-friction ring-pack designs in the Waukesha VGF 18GL engine confirmed total engine FEMP (friction mean effective pressure) reduction of 7-10% from the baseline configuration without significantly increasing oil consumption or blow-by flow. This represents a substantial (30-40%) reduction of the ringpack friction alone. The measured FMEP reductions were in good agreement with the model predictions. Further improvements via piston, lubricant, and surface designs offer additional opportunities. Tests of low-friction lubricants are in progress and preliminary results are very promising. The combined analysis of lubricant and surface design indicates that low-viscosity lubricants can be very effective in reducing friction, subject to component wear for extremely thin oils, which can be mitigated with further lubricant formulation and/or engineered surfaces. Hence a combined approach of lubricant design and appropriate wear reduction offers improved potential for minimum engine friction loss. Piston friction studies indicate that a flatter piston with a more flexible skirt, together with optimizing the waviness and film thickness on the piston skirt offer significant friction reduction. Combined with low-friction ring-pack, material and lubricant parameters, a total power cylinder friction

  2. Evaluation of Karst Soil Erosion and Nutrient Loss Based on RUSLE Model in Guizhou Province

    Science.gov (United States)

    Zeng, Cheng; Li, Yangbing; Bai, Xiaoyong; Luo, Guangjie

    2018-01-01

    Based on GIS technology and RUSLE model, the spatial variation characteristics of soil erosion were analyzed in karst areas, and the relationship between soil erosion and soil nutrient loss was discussed. The results showed that the soil differences in spatial variation between nutrient losses. The results illustrate the total soil erosion in is 10316.31 × 104t • a-1, accounting for 84.95% of the total land area in Guizhou Province. The spatial distribution of soil erosion showing the characteristics of the southeast to the northwest strip. The annual average soil erosion modulu is 691.94 t • km-2 • a-1, of which karst is 720.28t • km-2 • a-1 and non-karst is 689.53 t • km-2 • a-1. The total nutrient losses such as soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP) and total potassium (TK) were 596.72 × 104t • a-1 due to soil erosion, and SOC, TN and TP and TK were 38.13, 1.61, 0.41 and 14.70t • km-2 • a-1, respectively. The average amount of loss and total loss are the largest in non-karst, and four kinds of nutrient is the smallest in karst gorge. The spatial variation of soil erosion in the study area is the process of increasing the erosion area with the increase of the erosion rate, and the difference of the spatial distribution of soil erosion determines the spatial distribution of soil nutrient loss.

  3. Use of 3D MR reconstructions in the evaluation of glenoid bone loss: a clinical study

    International Nuclear Information System (INIS)

    Gyftopoulos, Soterios; Beltran, Luis S.; Yemin, Avner; Recht, Michael P.; Strauss, Eric; Meislin, Robert; Jazrawi, Laith

    2014-01-01

    To assess the ability of 3D MR shoulder reconstructions to accurately quantify glenoid bone loss in the clinical setting using findings at the time of arthroscopy as the gold standard. Retrospective review of patients with MR shoulder studies that included 3D MR reconstructions (3D MR) produced using an axial Dixon 3D-T1W-FLASH sequence at our institution was conducted with the following inclusion criteria: history of anterior shoulder dislocation, arthroscopy (OR) performed within 6 months of the MRI, and an estimate of glenoid bone loss made in the OR using the bare-spot method. Two musculoskeletal radiologists produced estimates of bone loss along the glenoid width, measured in mm and %, on 3D MR using the best-fit circle method, which were then compared to the OR measurements. There were a total of 15 patients (13 men, two women; mean age, 28, range, 19-51 years). There was no significant difference, on average, between the MRI (mean 3.4 mm/12.6 %; range, 0-30 %) and OR (mean, 12.7 %; range, 0-30 %) measurements of glenoid bone loss (p = 0.767). A 95 % confidence interval for the mean absolute error extended from 0.45-2.21 %, implying that, when averaged over all patients, the true mean absolute error of the MRI measurements relative to the OR measurements is expected to be less than 2.21 %. Inter-reader agreement between the two readers had an IC of 0.92 and CC of 0.90 in terms of percentage of bone loss. 3D MR reconstructions of the shoulder can be used to accurately measure glenoid bone loss. (orig.)

  4. Use of 3D MR reconstructions in the evaluation of glenoid bone loss: a clinical study

    Energy Technology Data Exchange (ETDEWEB)

    Gyftopoulos, Soterios; Beltran, Luis S.; Yemin, Avner; Recht, Michael P. [NYU Langone Medical Center, Department of Radiology, New York, NY (United States); Strauss, Eric; Meislin, Robert; Jazrawi, Laith [NYU Langone Medical Center, Center for Musculoskeletal Care, Department of Orthopaedic Surgery, New York, NY (United States)

    2014-02-15

    To assess the ability of 3D MR shoulder reconstructions to accurately quantify glenoid bone loss in the clinical setting using findings at the time of arthroscopy as the gold standard. Retrospective review of patients with MR shoulder studies that included 3D MR reconstructions (3D MR) produced using an axial Dixon 3D-T1W-FLASH sequence at our institution was conducted with the following inclusion criteria: history of anterior shoulder dislocation, arthroscopy (OR) performed within 6 months of the MRI, and an estimate of glenoid bone loss made in the OR using the bare-spot method. Two musculoskeletal radiologists produced estimates of bone loss along the glenoid width, measured in mm and %, on 3D MR using the best-fit circle method, which were then compared to the OR measurements. There were a total of 15 patients (13 men, two women; mean age, 28, range, 19-51 years). There was no significant difference, on average, between the MRI (mean 3.4 mm/12.6 %; range, 0-30 %) and OR (mean, 12.7 %; range, 0-30 %) measurements of glenoid bone loss (p = 0.767). A 95 % confidence interval for the mean absolute error extended from 0.45-2.21 %, implying that, when averaged over all patients, the true mean absolute error of the MRI measurements relative to the OR measurements is expected to be less than 2.21 %. Inter-reader agreement between the two readers had an IC of 0.92 and CC of 0.90 in terms of percentage of bone loss. 3D MR reconstructions of the shoulder can be used to accurately measure glenoid bone loss. (orig.)

  5. Piloted Simulation Evaluation of a Model-Predictive Automatic Recovery System to Prevent Vehicle Loss of Control on Approach

    Science.gov (United States)

    Litt, Jonathan S.; Liu, Yuan; Sowers, Thomas S.; Owen, A. Karl; Guo, Ten-Huei

    2014-01-01

    This paper describes a model-predictive automatic recovery system for aircraft on the verge of a loss-of-control situation. The system determines when it must intervene to prevent an imminent accident, resulting from a poor approach. It estimates the altitude loss that would result from a go-around maneuver at the current flight condition. If the loss is projected to violate a minimum altitude threshold, the maneuver is automatically triggered. The system deactivates to allow landing once several criteria are met. Piloted flight simulator evaluation showed the system to provide effective envelope protection during extremely unsafe landing attempts. The results demonstrate how flight and propulsion control can be integrated to recover control of the vehicle automatically and prevent a potential catastrophe.

  6. An evaluation of 1D loss model collections for the off-design performance prediction of automotive turbocharger compressors

    International Nuclear Information System (INIS)

    Harley, P; Spence, S; Early, J; Filsinger, D; Dietrich, M

    2013-01-01

    Single-zone modelling is used to assess different collections of impeller 1D loss models. Three collections of loss models have been identified in literature, and the background to each of these collections is discussed. Each collection is evaluated using three modern automotive turbocharger style centrifugal compressors; comparisons of performance for each of the collections are made. An empirical data set taken from standard hot gas stand tests for each turbocharger is used as a baseline for comparison. Compressor range is predicted in this study; impeller diffusion ratio is shown to be a useful method of predicting compressor surge in 1D, and choke is predicted using basic compressible flow theory. The compressor designer can use this as a guide to identify the most compatible collection of losses for turbocharger compressor design applications. The analysis indicates the most appropriate collection for the design of automotive turbocharger centrifugal compressors

  7. Evaluation of magnetic loss in a YBa sub 2 Cu sub 3 O sub x superconductor

    CERN Document Server

    Konishi, H; Futamura, M

    2003-01-01

    We measured the magnetic force between a YBa sub 2 Cu sub 3 O sub x (YBCO) superconductor and a Nd-Fe-B magnet while reciprocating the superconductor under the magnet. The magnetic force showed a hysteretic characteristic against the displacement of the superconductor. Magnetic loss calculated from the hysteresis curve decreased as the drive frequency increased. A mechanical model was used to analyze the characteristics of the magnetic loss. By adding the contribution of viscous force and repined flux lines to the mechanical model, we obtained good agreement between the analytical and experimental results. (author)

  8. Modeling Friction in Modelica with the Lund-Grenoble Friction Model

    OpenAIRE

    Aberger, Martin; Otter, Martin

    2002-01-01

    The properties of the Lund-Grenoble friction model are summarized and different types of friction elements - bearing friction, clutch, one-way clutch, are implemented in Modelica using this friction formulation. The dynamic properties of these components are determined in simulations and compared with the friction models available in the Modelica standard library. This includes also an automatic gearbox model where 6 friction elements are coupled dynamically.

  9. 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)

  10. Friction between Archwire of Different Sizes, Cross Section, Alloy and Brackets Ligated with Different Brands of Low Friction Elastic Ligatures- An Invitro Study.

    Science.gov (United States)

    Patil, Bhushan; Patil, Neeraj Suresh; Kerudi, Veerendra Virupaxappa; Chitko, Shrikant Shrinivas; Maheshwari, Amit Ratanlal; Patil, Harshal Ashok; Pekhale, Nikhita Popatrao; Tekale, Pawankumar Dnyandeo

    2016-04-01

    Friction in orthodontic treatment does exist and is thought to reduce the efficiency of orthodontic appliances during sliding mechanics. During sliding mechanics, a friction force is produced at the bracket archwire-ligature unit which tends to counteract the applied force and in turn resists the desired movement. The aim of this invitro study was to determine the friction between archwire of different sizes, cross section, alloy and brackets ligated with different brands of low friction elastic ligatures. An 0.022-in slot, 10 stainless steel brackets and various orthodontic archwires which were ligated with low-friction ligatures and subjected to evaluate frictional resistance i.e. static friction and dynamic friction. The archwires of 0.014″ and 0.016″ nickel titanium (NiTi), 0.016 × 0.022″ stainless steel (SS), 0.017 × 0.025″ NiTi, 0.017 × 0.025″ SS, 0.017 × 0.025″ titanium molybdenum alloy (TMA), 0.019 × 0.025″ SS were used. Each bracket/archwire combination was evaluated 10 times at room temperature of 27 ± 2°C. The study groups included Group I of conventional round shape module with reduced friction coating i.e. super slick and synergy and Group II contained figure of "8" shape module i.e. Octavia ties and Slide ligature. The mean static friction force and dynamic friction force for all 7 types of wires was lower in Group II (C, D) combined compared to Group I (A, B) and the difference was statistically very highly significant (pfriction mechanics.

  11. Friction anisotropy in boronated graphite

    International Nuclear Information System (INIS)

    Kumar, N.; Radhika, R.; Kozakov, A.T.; Pandian, R.; Chakravarty, S.; Ravindran, T.R.; Dash, S.; Tyagi, A.K.

    2015-01-01

    Graphical abstract: - Highlights: • Friction anisotropy in boronated graphite is observed in macroscopic sliding condition. • Low friction coefficient is observed in basal plane and becomes high in prismatic direction. • 3D phase of boronated graphite transformed into 2D structure after friction test. • Chemical activity is high in prismatic plane forming strong bonds between the sliding interfaces. - Abstract: Anisotropic friction behavior in macroscopic scale was observed in boronated graphite. Depending upon sliding speed and normal loads, this value was found to be in the range 0.1–0.35 in the direction of basal plane and becomes high 0.2–0.8 in prismatic face. Grazing-incidence X-ray diffraction analysis shows prominent reflection of (0 0 2) plane at basal and prismatic directions of boronated graphite. However, in both the wear tracks (1 1 0) plane become prominent and this transformation is induced by frictional energy. The structural transformation in wear tracks is supported by micro-Raman analysis which revealed that 3D phase of boronated graphite converted into a disordered 2D lattice structure. Thus, the structural aspect of disorder is similar in both the wear tracks and graphite transfer layers. Therefore, the crystallographic aspect is not adequate to explain anisotropic friction behavior. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy shows weak signature of oxygen complexes and functional groups in wear track of basal plane while these species dominate in prismatic direction. Abundance of these functional groups in prismatic plane indicates availability of chemically active sites tends to forming strong bonds between the sliding interfaces which eventually increases friction coefficient

  12. Friction anisotropy in boronated graphite

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, N., E-mail: niranjan@igcar.gov.in [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Radhika, R. [Crystal Growth Centre, Anna University, Chennai (India); Kozakov, A.T. [Research Institute of Physics, Southern Federal University, Rostov-on-Don (Russian Federation); Pandian, R. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Chakravarty, S. [UGC-DAE CSR, Kalpakkam (India); Ravindran, T.R.; Dash, S.; Tyagi, A.K. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2015-01-01

    Graphical abstract: - Highlights: • Friction anisotropy in boronated graphite is observed in macroscopic sliding condition. • Low friction coefficient is observed in basal plane and becomes high in prismatic direction. • 3D phase of boronated graphite transformed into 2D structure after friction test. • Chemical activity is high in prismatic plane forming strong bonds between the sliding interfaces. - Abstract: Anisotropic friction behavior in macroscopic scale was observed in boronated graphite. Depending upon sliding speed and normal loads, this value was found to be in the range 0.1–0.35 in the direction of basal plane and becomes high 0.2–0.8 in prismatic face. Grazing-incidence X-ray diffraction analysis shows prominent reflection of (0 0 2) plane at basal and prismatic directions of boronated graphite. However, in both the wear tracks (1 1 0) plane become prominent and this transformation is induced by frictional energy. The structural transformation in wear tracks is supported by micro-Raman analysis which revealed that 3D phase of boronated graphite converted into a disordered 2D lattice structure. Thus, the structural aspect of disorder is similar in both the wear tracks and graphite transfer layers. Therefore, the crystallographic aspect is not adequate to explain anisotropic friction behavior. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy shows weak signature of oxygen complexes and functional groups in wear track of basal plane while these species dominate in prismatic direction. Abundance of these functional groups in prismatic plane indicates availability of chemically active sites tends to forming strong bonds between the sliding interfaces which eventually increases friction coefficient.

  13. Technical and Economical Evaluations of Canola Harvesting Losses in Different Maturity Stages Using Three Different Combine Harverster Heads

    Directory of Open Access Journals (Sweden)

    J Taghinazhad

    2013-09-01

    Full Text Available Rapeseed cultivation in Iran is growing rapidly while this product has been facing specific problems. Every year a significant portion of edible oil is imported to the country from other countries. Despite this deficit, a great amount of canola is being lost every year. Therefore, in compliance with technical points, adding a suitable platform to the exisiting machineries may reduce the losses. A field study was conducted in Moghan Agricultural Research Centre to study the technical and economical characteristics of harvesting machineries and evaluate Canola harvesting losses in different maturity stages, using three different combine harvester heads. The experiments were conducted in a completely randomized\tsplit split plot design with four replications. The main plot included seed maturity stage at three levels: A 60%, B 70% and C 80%, and the subplot was the harvester’s ground speed at three levels: A 1.5, B 2.5 and C 3.5 km h-1. The sub-subplot was combine head type with three forms: A Mechanical, B Hydraulically Joybar and C Hydraulically Biso's Head. The results of ANOVA showed that maximum cutter bar losses occurred with Mechanical Head (5.36% while the loss of Hydraulically Joybar's and Biso's head were 4.28 and 4.13 %, respectively. The results also showed that the maximum cutter bar losses occurred when 80% of seeds were matured and adequate time for canola harvesting was 70% of seeds maturity. The results of analysing the effects of harvesting ground speeds showed that the maximum cutter bar losses occurred with the speed of 3.5 km h-1. Finally, the results showed that the minimum cutter bar loss was obtained with Hydraulically Joybar's head considering the benefit per cost ratio. The cost for Mechanical head and Hydraulically Biso's head were 13500 and 262500 Rial ha-1, respectively.

  14. Friction, adhesion and wear properties of PDMS films on silicon sidewalls

    International Nuclear Information System (INIS)

    Penskiy, I; Gerratt, A P; Bergbreiter, S

    2011-01-01

    This paper demonstrates the first tests of friction, adhesion and wear properties of thin poly(dimethylsiloxane) (PDMS) films on the sidewalls of silicon-on-insulator structures. The test devices were individually calibrated using a simple method that included optical and electrical measurements. The static coefficient of friction versus normal pressure curves were obtained for PDMS–PDMS, PDMS–silicon and silicon–silicon sidewall interfaces. The effects of aging on friction and adhesion properties of PDMS were also evaluated. The results of friction tests showed that the static coefficient of friction follows the JKR contact model, which means that the friction force depends on the apparent area of contact. The wear tests showed high resistance of PDMS to abrasion over millions of cycles.

  15. Thermodynamic evaluation of distillation columns using exergy loss profiles: a case study on the crude oil atmospheric distillation column

    Energy Technology Data Exchange (ETDEWEB)

    Tarighaleslami, Amir Hossein [Mahshahr Branch, Islamic Azad University, Chemical Engineering Faculty, Mahshar, Khouzestan (Iran, Islamic Republic of); Omidkhah, Mohammad Reza [Tarbiat Modares University, Chemical Engineering Department, Faculty of Engineering, Tehran (Iran, Islamic Republic of); Ghannadzadeh, Ali [University of Toulouse, Department of Process and System Engineering, Chemical Engineering Laboratory, Toulouse (France); Hoseinzadeh Hesas, Roozbeh [University of Malaya, Chemical Engineering Department, Faculty of Engineering, Kuala Lumpur (Malaysia)

    2012-06-15

    This paper presents a case study on the crude oil atmospheric distillation column of Tabriz refinery plant to show the applicability of exergy loss profiles in thermodynamic examination of the different retrofit options. The atmospheric distillation column of Tabriz refinery has been revamped as a consequence of increase of the plant capacity to 100,000 bpd. To cover the deficit of feedstock of the revamped unit, a blend of the existing feedstock with imported crude oil is used as a feedstock. However, to investigate how the blend of these two different types of crudes as a feedstock has an influence on the operating conditions, the examination of the column is needed. Exergy as a comprehensive thermodynamic property which translates the temperature, pressure and composition change into a common unit has been chosen to evaluate the distillation column thermodynamically. Furthermore, the exergy loss profile of the base case serves as a scoping tool to pinpoint the source of inefficiencies. Then, the exergy loss profile as a screening tool has found the retrofit options which are likely to yield greatest energy saving from a list of retrofit options proposed by the industrial partner. In the presented case study, the exergy loss profile identifies the best retrofit option with 17.16% reduction in exergy losses, which finally lead to 3.6% reduction of primary fuel demand. (orig.)

  16. Evaluation of the impact of density gradient centrifugation on fetal cell loss during enrichment from maternal peripheral blood.

    Science.gov (United States)

    Emad, Ahmed; Drouin, Régen

    2014-09-01

    Physical separation by density gradient centrifugation (DGC) is usually used as an initial step of multistep enrichment protocols for purification of fetal cells (FCs) from maternal blood. Many protocols were designed but no single approach was efficient enough to provide noninvasive prenatal diagnosis. Procedures and methods were difficult to compare because of the nonuniformity of protocols among different groups. Recovery of FCs is jeopardized by their loss during the process of enrichment. Any loss of FCs must be minimized because of the multiplicative effect of each step of the enrichment process. The main objective of this study was to evaluate FC loss caused by DGC. Fetal cells were quantified in peripheral blood samples obtained from both euploid and aneuploid pregnancies before and after enrichment by buoyant DGC using Histopaque 1.119 g/mL. Density gradient centrifugation results in major loss of 60% to 80% of rare FCs, which may further complicate subsequent enrichment procedures. Eliminating aggressive manipulations can significantly minimize FC loss. Data obtained raise questions about the appropriateness of the DGC step for the enrichment of rare FCs and argues for the use of the alternative nonaggressive version of the procedure presented here or prioritizing other methods of enrichments. © 2014 John Wiley & Sons, Ltd.

  17. TECHNICAL FACT SHEET: A Systematic Evaluation of Dissolved Metals Loss during Water Sample Filtration

    Science.gov (United States)

    This research study examined how water quality collection and filtration approaches, including commonly used capsule and disc syringe filters, may cause losses in the amounts of soluble lead and copper found in a sample. A variety of commercially available filter materials with a...

  18. Using a phosphorus loss model to evaluate the Kentucky phosphorus index

    Science.gov (United States)

    U.S. Department of Agriculture’s Natural Resource Conservation Service (USDA-NRCS) has recently revised its 590 Nutrient Management Conservation Standard. As part of this revision, USDA-NRCS is requiring states to test the accuracy of their phosphorus (P) index using either measured P loss data or s...

  19. An evaluation of intra-operative and post-operative blood loss in ...

    African Journals Online (AJOL)

    Background: Total knee replacement is a rewarding and reliable procedure, producing a lasting relief to severe knee pains. However, significant blood loss usually in the post-operative period may be a challenge, necessitating prompt restoration of circulating blood volume to minimize morbidity and mortality. The aim of this ...

  20. Evaluation of the performance degradation at PAFC effect of operating conditions on acid loss

    Energy Technology Data Exchange (ETDEWEB)

    Miyoshi, Hideaki; Uchida, Hiroyuki; Watanabe, Masahiro [Yamanashi Univ., Kofu (Japan)] [and others

    1996-12-31

    As a complimentary research project to the demonstration project of 5MW and 1 MW PAFC plants, the mechanism and rate of deterioration of the cells and stacks have been studied from 1995 FY conducted by NEDO, with the objective of establishing an estimation method for the service life-time of the cell stacks. As part of this project, this work has been performed to clarify basic phenomena of the performance degradation at PAFCs jointly by Yamanashi University, PAFC-TRA and PAFC manufacturers. The acid loss into exhaust gases is one of life limiting factors in PAFCs. To design the cells of long-life, it is important to estimate the phosphoric acid loss and to contrive ideas eliminating it. With the objective of obtaining basic data for simulating the acid loss in the large size cells, the effect of the operating conditions on the acid loss into exhaust gases has been studied experimentally by using a single cell with an active electrode area of 100 cm{sup 2}.

  1. Radiochromium (chromium-51) evaluation of gastrointestinal blood loss associated with placebo, aspirin, and nabumetone

    International Nuclear Information System (INIS)

    Lussier, A.; LeBel, E.

    1987-01-01

    Gastrointestinal blood loss is one of the most serious clinical events induced by drugs. To date, almost no nonsteroidal anti-inflammatory drug has been shown to be devoid of that side effect in a strictly controlled study. The objective of this study was to assess quantitatively, by use of radioactive chromium (chromium-51)-labeled red blood cells, gastrointestinal blood loss associated with nabumetone (1000 mg daily), aspirin (3.6 g daily), and placebo. A total of 37 normal subjects, divided among the three treatment groups and a fourth group that received no treatment, were assessed clinically and quantitatively for gastrointestinal blood loss over a period of 28 days of active treatment. The results with chromium-51, analyzed on a logarithmic scale, revealed no statistically significant differences between the nabumetone, placebo, and control groups. Gastrointestinal blood loss in the aspirin group, however, was elevated when compared with all other groups at a high level of statistical significance (p less than 0.001). It is concluded that, under conditions in which aspirin causes substantial gastrointestinal microbleeding, nabumetone is not significantly different from placebo

  2. Farm-system modeling to evaluate environmental losses, profitability, and best management practice cost-effectiveness

    Science.gov (United States)

    To meet Chesapeake Bay Total Maximum Daily Load requirements for agricultural pollution, conservation districts and farmers are tasked with implementing best management practices (BMPs) that reduce farm losses of nutrients and sediment. The importance of the agricultural industry to the regional eco...

  3. An evaluation of peat loss from an Everglades tree island, Florida, USA

    Directory of Open Access Journals (Sweden)

    S. Aich

    2014-03-01

    Full Text Available The tree islands of the Everglades are considered to be biodiversity “hotspots”, where the majority of terrestrial species of the Everglades are found. Drainage for agricultural and urban development in the early 1900s has had a severe impact, converting many of them into “ghost tree islands” which have lost most of their woody vegetation and much of their altitude (elevation. A survey conducted in 1973 on one of the prominent ghost tree islands, named “Dineen Island”, provides insights into the past. We compared the results of the 1973 survey with those of a survey conducted in 2009, in order to examine changes in Dineen Island that had taken place over 36 years and to provide information about general trends in the Everglades. Peat loss at Dineen Island was roughly 4 mm yr-1. This subsidence, as a consequence of peat loss, has been accompanied by losses in nitrogen and phosphorus of 234 and 2.5 metric tons (4.5 and 0.05 metric tons per hectare, respectively. As many of the Everglades tree islands have been lost from the landscape due to historical water management practices, quantifying nutrient losses from this ecosystem may be useful in helping to predict non-anthropogenic nutrient biogeochemistry shifts in Everglades oligotrophy.

  4. Evaluation of torque loss in Co-Cr castable abutments after cyclic loading

    Directory of Open Access Journals (Sweden)

    Somayeh Zeighami

    2018-03-01

    Conclusion: Misfit between the castable implant components can cause torque loss before and after cyclic loading. However, it is more appropriate to relate the results of this study to the screw loosening of the above mentioned abutments than judging their clinical performance.

  5. Amino Acid Signatures to Evaluate the Beneficial Effects of Weight Loss

    DEFF Research Database (Denmark)

    Geidenstam, Nina; Magnusson, Martin; Danielsson, Anders P H

    2017-01-01

    -associated amino acids from the MDC-CC, alanine, isoleucine, tyrosine, phenylalanine, and glutamate decreased after weight loss, while asparagine increased after weight maintenance. These changes were validated in the replication cohort. Scores that were constructed based on obesity-associated amino acids...

  6. Evaluation of the energy component in the main grid tariff and the use of marginal loss rates; Evaluering av energileddet i sentralnettstariffen og bruk av marginaltapssatser

    Energy Technology Data Exchange (ETDEWEB)

    Bjoerndal, Endre; Bjoerndal, Mette

    2010-11-15

    In this report, we make an evaluation of the energy component of the central grid tariff and the use of marginal loss rates. We will first review the theory of optimum transmission tariffs and describes how the marginal loss rates are calculated and how these are used in combination with the system price in the current transmission costs. We describe the trend in the Swedish marginal loss schedule, and we refer the very short development in the PJM area (U.S. east coast). As the Swedish and the Norwegian system is apparently based on the same principles, we problematize the lack of harmonization, since the systems actually are now very different. There is little doubt that Statnett has refined and improved methods for calculating the marginal loss rates, while ensuring that bottlenecks are still handled fairly easy by a few large price areas on Nord Pool Spot. We discuss the relationship between loss-tariff and congestion management, and we recommend that Statnett considering using the area price as the settlement price. This will make it much easier for operators to take account of losses. (Author)

  7. CNE (Embalse nuclear power plant): probabilistic safety study. Loss of service water. Probabilistic evaluation and analysis through events sequence

    International Nuclear Information System (INIS)

    Couto, A.J.; Perez, S.S.

    1987-01-01

    This work is part of a study on the service water systems of the Embalse nuclear power plant from a safety point of view. The faults of service water systems of high and low pressure that can lead to situations threatening the plant safety were analyzed in a previous report. The event 'total loss of low pressure service water' causes the largest number of such conditions. Such event is an operational incident that can lead to an accident situation due to faults in the required process systems or by omission of a procedure. The annual frequency of the event 'total loss of low pressure service water' is calculated. The main contribution comes from pump failure. The evaluation of the accident sequences shows that the most direct way to the liberation of fission products is the loss of steam generators as heat sink. The contributions to small and large LOCA and electric supply loss are analyzed. The sequence that leads to tritium release through boiling of moderator is also evaluated. (Author)

  8. Development of 4S and related technologies (7). Analytical evaluation of RVACS performance under loss of stacks condition

    International Nuclear Information System (INIS)

    Nishimura, Satoshi; Nishi, Yoshihisa; Ueda, Nobuyuki

    2009-01-01

    The 4S (Super-Safe, Small and Simple) reactor is a sodium-cooled fast reactor aiming at an application to dispersed energy source and multi-purpose use. An introduction of RVACS (Reactor Vessel Auxiliary Cooling System) can enhance the passive decay heat removal capability. In the present study, the RVACS performance in 4S reactor (10MWe, pool-type) was analytically evaluated under the functional loss of RVACS stack condition, which is considered as a beyond design basis event. A protected loss of heat sink accident was selected and simulated to evaluate the capability of RVACS to cool the plant under such an unusual condition. The three-dimensional thermal hydraulic analysis was conducted by PHOENICS code. Analytical results show that the functional loss of air outlet stack has more effect on RVACS performance than that of air inlet stack. The air flow rate in RVACS under the functional loss of one out of two outlet stacks decreases up to approximately 60% and the heat removal rate approximately 70%, comparing with those under the normal stack condition. However, the maximum hot plenum temperature is low enough to satisfy the safety criteria. (author)

  9. Structural Damping with Friction Beams

    Directory of Open Access Journals (Sweden)

    L. Gaul

    2008-01-01

    Full Text Available In the last several years, there has been increasing interest in the use of friction joints for enhancing damping in structures. The joints themselves are responsible for the major part of the energy dissipation in assembled structures. The dissipated work in a joint depends on both the applied normal force and the excitation force. For the case of a constant amplitude excitation force, there is an optimal normal force which maximizes the damping. A ‘passive’ approach would be employed in this instance. In most cases however, the excitation force, as well as the interface parameters such as the friction coefficient, normal pressure distribution, etc., are not constant. In these cases, a ‘semi-active’ approach, which implements an active varying normal force, is necessary. For the ‘passive’ and ‘semi-active’ approaches, the normal force has to be measured. Interestingly, since the normal force in a friction joint influences the local stiffness, the natural frequencies of the assembled structure can be tuned by adjusting the normal force. Experiments and simulations are performed for a simple laboratory structure consisting of two superposed beams with friction in the interface. Numerical simulation of the friction interface requires non-linear models. The response of the double beam system is simulated using a numerical algorithm programmed in MATLAB which models point-to-point friction with the Masing friction model. Numerical predictions and measurements of the double beam free vibration response are compared. A practical application is then described, in which a friction beam is used to damp the vibrations of the work piece table on a milling machine. The increased damping of the table reduces vibration amplitudes, which in turn results in enhanced surface quality of the machined parts, reduction in machine tool wear, and potentially higher feed rates. Optimal positioning of the friction beams is based on knowledge of the mode

  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. Evaluation of the relation between lipid coat, transepidermal water loss, and skin pH.

    Science.gov (United States)

    Algiert-Zielińska, Barbara; Batory, Mirella; Skubalski, Janusz; Rotsztejn, Helena

    2017-11-01

    The epidermis is an epidermal barrier which accumulates lipid substances and participates in skin moisturizing. An evaluation of the epidermal barrier efficiency can be made, among others, by the measurement of the following values: the lipid coat, the transepidermal water loss (TEWL) index, and pH. The study involved 50 Caucasian, healthy women aged 19-35 years (mean 20.56). Measurements were made using Courage & Khazaka Multi Probe Adapter MPA 580: Tewameter TM 300, pH-Meter PH 905, Sebumeter SM 815. The areas of measurements included forehead, nose, left cheek, right cheek, chin, and thigh. In the T-zone, the lipid coat was in the range between 0 and 270 μg/cm 2 (mean 128 μg/cm 2 ), TEWL between 1 and 55 g/m 2 /h (mean 11.1 g/m 2 /h), and pH 4.0-5.6 (mean 5.39). Lower values of the lipid coat up to 100 μg/cm 2 were accompanied by TEWL greater than 30 g/m 2 /h and less acidic pH of 5.6-9.0. In the U-zone the range of lipid coat was up to 200 μg/cm 2 (mean 65.2 μg/cm 2 ), the skin pH remained 4.0-5.6 (mean 5.47), and TEWL was in the range between 1 and 20 g/m 2 /h (mean 8.7 g/m 2 /h). Lower values of the lipid coat up to 100 μg/cm 2 were accompanied by TEWL between 1 and 20 g/m 2 /h and less acidic pH of 5.6-9.0. High values of the lipid coat between 180 and 200 μg/cm 2 were connected with TEWL of 1-15 g/m 2 /h. On the skin of the thigh, we observed a very thin lipid coat - 35 μg/cm 2 (mean 5.6 μg/cm 2 ), pH (mean 5.37), and TEWL (mean 8.5 g/m 2 /h) were considered by us to be within regular limits. In the T-zone, a thinner lipid coat resulted in relatively high TEWL and pH levels changing toward alkaline. In the U-zone, thinner lipid coat was accompanied by lower TEWL and pH changing toward alkaline. We also observed that lower values of lipid coat up to 100 μg/cm 2 were associated with higher pH values ranging toward the basic character pH 5.6-9.0). © 2017 The International Society of Dermatology.

  12. 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.

  13. Quantum Drude friction for time-dependent density functional theory

    Science.gov (United States)

    Neuhauser, Daniel; Lopata, Kenneth

    2008-10-01

    Friction is a desired property in quantum dynamics as it allows for localization, prevents backscattering, and is essential in the description of multistage transfer. Practical approaches for friction generally involve memory functionals or interactions with system baths. Here, we start by requiring that a friction term will always reduce the energy of the system; we show that this is automatically true once the Hamiltonian is augmented by a term of the form ∫a(q ;n0)[∂j(q,t)/∂t]ṡJ(q)dq, which includes the current operator times the derivative of its expectation value with respect to time, times a local coefficient; the local coefficient will be fitted to experiment, to more sophisticated theories of electron-electron interaction and interaction with nuclear vibrations and the nuclear background, or alternately, will be artificially constructed to prevent backscattering of energy. We relate this term to previous results and to optimal control studies, and generalize it to further operators, i.e., any operator of the form ∫a(q ;n0)[∂c(q,t)/∂t]ṡC(q)dq (or a discrete sum) will yield friction. Simulations of a small jellium cluster, both in the linear and highly nonlinear excitation regime, demonstrate that the friction always reduces energy. The energy damping is essentially double exponential; the long-time decay is almost an order of magnitude slower than the rapid short-time decay. The friction term stabilizes the propagation (split-operator propagator here), therefore increasing the time-step needed for convergence, i.e., reducing the overall computational cost. The local friction also allows the simulation of a metal cluster in a uniform jellium as the energy loss in the excitation due to the underlying corrugation is accounted for by the friction. We also relate the friction to models of coupling to damped harmonic oscillators, which can be used for a more sophisticated description of the coupling, and to memory functionals. Our results open the

  14. [Transcultural adaptation of an instrument to evaluate hearing handicap in workers with noise-induced hearing loss].

    Science.gov (United States)

    Holanda, Wanessa Tenório Gonçalves; de Lima, Maria Luiza Carvalho; Figueiroa, José Natal

    2011-01-01

    The noise-induced hearing loss (NIHL) is a chronic and irreversible disease resulting of the exposure to noise in high levels at work. Even in the beginning, this hearing loss can damage in many degrees the worker's quality of life. Before this study, there wasn't an instrument, in Portuguese, to evaluate the psychosocial disadvantages of workers with NIHL. The aim of this research was to make a transcultural adaptation of an especific instrument to evaluate the hearing handicap from the original language to Portuguese, and check the reliability and legitimacy. The selected instrument passed by a process of semantic equivalence that was conducted in five stages: translation, back translation, critical appraisal of the versions, pre-test and a final review by a multi-professional group to develop a consensual version of the instrument for current use in Brazil. The instrument called "Inabilities Scale and Hearing Handicap" had, in general, acceptable psychometric measures, considering the little size of the sample and the fact that workers' hearing loss weren't too significant. Therefore, the Portuguese version of this instrument needs to be further tested in a representative sample of Brazilian workers with NIHL to ratify its utility in order to evaluate hearing handicap in this population.

  15. Ball-on-DiscTribometers Protocol Development: Loss of Lubrication Evaluation

    Science.gov (United States)

    2016-02-01

    data ...........................................13 Fig. 12 Traction coefficient of the incident caused by a loose bolt .................15 Fig. 13...Damaged parts caused by a loose bolt .................................................16 Fig. 14 LoL traction coefficient’s time to failure...loss of lubrication occurred in March 2009 with a Sikorsky S-92 helicopter off the coast of Canada.2 The Sikorsky’s filter-bowl mounting studs

  16. Evaluation of torque loss value of MAD/MAM zirconia abutments with prefabricated titanium abutments

    OpenAIRE

    Marzieh Alikhasi; Roshanak Baghaie; Nasim khosronejad

    2013-01-01

    Background and Aims: In response to esthetic demand of patients, ceramic abutments have been developed. Despite esthetic of zirconia abutments, machining accuracy of these abutments has always been a question. Any misfit in the abutment-implant interface connection can lead to detorque and screw loosening. The aim of this study was to compare torque loss value of manually aided design/manually aided manufacture (MAD/MAM) zirconia abutments with prefabricated titanium abutments. Materials and ...

  17. Evaluating the Role and Effects of Precipitation on Relativistic Electron Losses during Storms

    Science.gov (United States)

    Chen, Y.; Fu, X.

    2016-12-01

    Theoretic studies have suggested that during storm times various waves (e.g., whistler-mode chorus and electromagnetic ion cyclotron waves) can cause significant precipitation of relativistic ( MeV) electrons that are originally trapped inside the outer radiation belt. However, the role of precipitation and its quantitative contribution to the losses of outer-belt electrons remain open questions. In this study, we tackle these questions by systemically examining the latest wave and electron in-situ, simultaneous observations made at different altitudes by Van Allen Probes from near equator, NOAA POES at low Earth orbits near/across electron loss cone, and BARREL under the mesosphere. After calibrating with DEMTER observations, we first confirm and quantify the response of POES MEPED proton channels to MeV electrons. Next, we identify a list of precipitation events from BARREL and POES measurements, examine the temporal adn spatial relation between the two data sets, and estimate the intensities of electron precipitation with ascertained uncertainties. Then, from Van Allen Probes data, we select another list of dropout events during storms. By cross checking the above two lists, we are able to determine the causal relation between precipitation and dropouts through individual case as well as statistical studies so as to quantify the contributions from precipitation. This study mainly focuses on the relatively small L-shells with positive phase space density radial gradient in order to alleviate the impacts from outward radial diffusion and adiabatic effects. Based upon the recent discovery of cross-energy cross-pitch angle coherence, we pay particular attention to the cross-term diffusions which may account for the extra "loss" needed by observed MeV electron dropouts. Results from this observational study will advance our knowledge on the loss mechanism of outer-belt electrons, and thus lay down another stepping stone towards high-fidelity physics-based models for

  18. Sensory evaluation and cooking loss of meat of broiler chicken fed probiotics and thyme essential oil

    Directory of Open Access Journals (Sweden)

    Ebrahim Alfaig

    2014-05-01

    Full Text Available A study was conducted to determine the effect of probiotics and thyme essential oil (TEO as feed additives on the sensory attributes, cooking loss and the texture of broiler chicken meat. Day-old broilers Ross 308  (n = 400 were randomly divided into four groups based on the feed supplement as follows: control, probiotics 0.05%, TEO 0.05% and combination of probiotics and TEO, while the fattening period was 42 days. Warner Bratzler shear force, cooking loss and the following sensory attributes (colour, odour, taste, texture, meat decomposing and overall acceptability were tested. The obtained results of the Warner Bratzler shear force show that there was significant different (P < 0.05 between control and TEO group and for the cooking loss there was no significant difference between groups. The descriptive sensory analysis results show that the probiotics group results were somewhat similar to that obtained by control while the TEO group and the combination group results were similar. Regarding the sensory analysis we can state that the combination of the probiotics and TEO have a positive effect on the chicken meat sensory characteristics.

  19. Evaluation of torque loss value of MAD/MAM zirconia abutments with prefabricated titanium abutments

    Directory of Open Access Journals (Sweden)

    Marzieh Alikhasi

    2013-04-01

    Full Text Available Background and Aims: In response to esthetic demand of patients, ceramic abutments have been developed. Despite esthetic of zirconia abutments, machining accuracy of these abutments has always been a question. Any misfit in the abutment-implant interface connection can lead to detorque and screw loosening. The aim of this study was to compare torque loss value of manually aided design/manually aided manufacture (MAD/MAM zirconia abutments with prefabricated titanium abutments. Materials and Methods: Seven titanium abutments (Branemark RP, Easy abutment and seven copy milled abutments which were duplicated from the prefabricated Zirkonzhan (ZirkonZahn, Sand in Taufers, Italy were prepared. After sintering process of zirconia abutment, all abutments were fastened with a torque screw under 35 Ncm. Detorque measurements were performed per group pushing the reverse button of the Torque controller soon after screw tightening with values registered. The mean torque loss were calculated and compared using Student's t test. Results: The mean of torque loss was 12.71 Ncm with standard deviation of 1.70 for prefabricated titanium abutments and 15.50 Ncm with standard deviation of 4.67 for MAD-MAM abutments. The difference between the two groups was not statistically significant (P=0.23. Conclusion: Within the limitation of this study, MAD-MAM ceramic abutments could maintain the applied torque comparing to the prefabricated abutments.

  20. Automated vehicle location, data recording, friction measurement and applicator control for winter road maintenance.

    Science.gov (United States)

    2010-02-01

    The first part of this project conducted a detailed evaluation of the ability of a new friction measurement system to : provide an accurate measure of road conditions. A system that records friction coefficient as a function of road : location was de...

  1. Friction and wear properties of Cu and Fe-based P/M bearing materials

    International Nuclear Information System (INIS)

    Tufekci, Kenan; Kurbanoglu, Cahit; Durak, Ertugrul; Tunay, R. Fatih

    2006-01-01

    The performances of porous bearings under different operating conditions were experimentally investigated in this study. Material groups studied are 90%Cu + 10%Sn bronze and 1%C + % balance Fe iron-based self-lubricating P/M bearings at constant (85%) density. In the experiments, the variation of the coefficient of friction and wear ratio of those two different group materials for different sliding speeds, loads, and temperatures were investigated. As a result, the variation of the friction coefficient - temperature for both constant load, and constant sliding speed, friction coefficient - average bearing pressure, PV - wear loss and temperature-wear loss curves were plotted and compared with each other for two materials, separately. The test results showed that Cu-based bearings have better friction and wear properties than Fe-based bearings

  2. Developing a predation index and evaluating ways to reduce salmonid losses to predation in the Columbia River basin

    International Nuclear Information System (INIS)

    Nigro, A.A.

    1990-12-01

    We report our results of studies to develop a predation index and evaluate ways to reduce juvenile salmonid losses to predation in the Columbia River Basin. Study objectives of each were: develop an index to estimate predation losses of juvenile salmonids (Oncorhynchus spp) in reservoirs throughout the Columbia River Basin, describe the relationships among predator-caused mortality of juvenile salmonids and physical and biological variables, examine the feasibility of developing bounty, commercial or recreational fisheries on northern squawfish (Ptychocheilus oregonensis) and develop a plan to evaluate the efficacy of predator control fisheries; determine the economic feasibility of developing bounty and commercial fisheries for northern squawfish, assist ODFW with evaluating the economic feasibility of recreational fisheries for northern squawfish and assess the economic feasibility of utilizing northern squawfish, carp (Cyprinus carpio) and suckers (Castostomus spp) in multispecies fisheries; evaluate commercial technology of various fishing methods for harvesting northern squawfish in Columbia River reservoirs and field test the effectiveness of selected harvesting systems, holding facilities and transportation systems; and modify the existing Columbia River Ecosystem Model (CREM) to include processes necessary to evaluate effects of removing northern squawfish on their population size structure and abundance, document the ecological processes, mathematical equations and computer (FORTRAN) programming of the revised version of CREM and conduct systematic analyses of various predator removal scenarios, using revised CREM to generate the simulations. Individual reports are indexed separately

  3. Heat Control via Torque Control in Friction Stir Welding

    Science.gov (United States)

    Venable, Richard; Colligan, Kevin; Knapp, Alan

    2004-01-01

    In a proposed advance in friction stir welding, the torque exerted on the workpiece by the friction stir pin would be measured and controlled in an effort to measure and control the total heat input to the workpiece. The total heat input to the workpiece is an important parameter of any welding process (fusion or friction stir welding). In fusion welding, measurement and control of heat input is a difficult problem. However, in friction stir welding, the basic principle of operation affords the potential of a straightforward solution: Neglecting thermal losses through the pin and the spindle that supports it, the rate of heat input to the workpiece is the product of the torque and the speed of rotation of the friction stir weld pin and, hence, of the spindle. Therefore, if one acquires and suitably processes data on torque and rotation and controls the torque, the rotation, or both, one should be able to control the heat input into the workpiece. In conventional practice in friction stir welding, one uses feedback control of the spindle motor to maintain a constant speed of rotation. According to the proposal, one would not maintain a constant speed of rotation: Instead, one would use feedback control to maintain a constant torque and would measure the speed of rotation while allowing it to vary. The torque exerted on the workpiece would be estimated as the product of (1) the torque-multiplication ratio of the spindle belt and/or gear drive, (2) the force measured by a load cell mechanically coupled to the spindle motor, and (3) the moment arm of the load cell. Hence, the output of the load cell would be used as a feedback signal for controlling the torque (see figure).

  4. 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

  5. The measurement of friction coefficient down to 1.8 K for LHC Magnets

    CERN Document Server

    Artoos, K; Poncet, Alain; Savary, F; Veness, R J M

    1994-01-01

    The Large Hadron Collider (LHC) proposed for construction at CERN consists of a series of high field superconducting dipole magnet operating at 1.8K. The mechanical structure of these magnets contains many components in close contact. A knowledge of the friction coefficient between these components is required. Indeed, during assembly and cool down of the magnets, prestresses must be transferred to the superconducting coils. During operation, frictional heating may provoke loss of superconductivity. A machine has been built at CERN to measure the coefficient of friction from room temperature down to 1.8K. This paper describes the cryogenic tribometer and the results collected to date.

  6. Factors influencing pursuit of hearing evaluation: Enhancing the health belief model with perceived burden from hearing loss on communication partners.

    Science.gov (United States)

    Schulz, Kristine A; Modeste, Naomi; Lee, Jerry; Roberts, Rhonda; Saunders, Gabrielle H; Witsell, David L

    2016-07-01

    There is limited application of health behavior-based theoretical models in hearing healthcare, yet other fields utilizing these models have shown their value in affecting behavior change. The health belief model (HBM) has demonstrated appropriateness for hearing research. This study assessed factors that influence an individual with suspected hearing loss to pursue clinical evaluation, with a focus on perceived burden of hearing loss on communication partners, using the HBM as a framework. Cross-sectional design collecting demographics along with three validated hearing-loss related questionnaires. Patients from Duke University Medical Center Otolaryngology Clinic aged 55-75 years who indicated a communication partner had expressed concern about their hearing. A final sample of 413 completed questionnaire sets was achieved. The HBM model construct 'cues to action' was a significant (p loss on communication partners was a significant (p model fit when added to the HBM: 72.0% correct prediction when burden is added versus 66.6% when not (p models in hearing healthcare is warranted.

  7. [The Evaluation of Medical Demographic and Economic Losses of the Region Conditioned by Mortality of Lung Cancer].

    Science.gov (United States)

    Zukov, R A; Modestov, A A; Safontsev, I P; Slepov, E V; Narkevich, A N

    2017-11-01

    The article presents evaluation of medical demographic and economic losses of population of the Krasnoyarskii kraii conditioned by mortality of lung cancer in 2010-2014 using DALY technology. In the Krasnoyarskii kraii, during 2010-2014 64,712 individuals died because of lung cancer. The mortality of male population surpasses corresponding indices of mortality of females up to 3.9 times. In the region, the standardized indicator mortality of lung cancer among males annually surpasses the same indicator among females at maximum up to 8.1 times. The DALY maximal absolute losses of among males were registered in 2010 and 2013 and fell on age group of 55-59 years and among females on the age group of 60-64 years in 2014. The maximal (up to 5.2 times) difference in values of DALY indicator was established in 2010 between male and female population. the maximal gap in in DALY indices between male and female population was established in the age of 55-59 years. Almost half of DALY losses among males was established in 2013 and among females in 2014. The total losses of gross regional product in the region because of mortality conditioned by lung cancer made up to 29.8 billions of rubles in 2010-2014.

  8. An empirical evaluation of the translation to Brazilian Portuguese of the Loss of Control over Eating Scale (LOCES

    Directory of Open Access Journals (Sweden)

    Felipe Q. da Luz

    2016-02-01

    Full Text Available Abstract Background Loss of control over eating is a key feature of the most prevalent eating disorders. The Loss of Control over Eating Scale (LOCES enables a thorough assessment of loss of control over eating. Objective This study empirically evaluated the translation of the LOCES from English to Brazilian Portuguese. Methods The scale was translated to Brazilian Portuguese and back translated to English in order to check accuracy of the translation. Two hundred and ninety-three medicine and nursing students, 60 males and 233 females, 18-55 years old, with mean body mass index (BMI 23.2 kg/m2 (SD 4.1, recruited between August and December 2014, answered the Brazilian Portuguese LOCES. An exploratory factor analysis was performed. Results Exploratory factor analysis of the Brazilian Portuguese LOCES showed three distinct factors of the loss of control over eating (disgust/negative sensations, cognitive experiences/dissociation, and “positive” effects as well as moderate consistency with previous reports of exploratory factor analysis of the English version. Discussion This study showed satisfactory translation of the LOCES from English to Brazilian Portuguese, which is now ready for further validation.

  9. Bottom friction optimization for a better barotropic tide modelling

    Science.gov (United States)

    Boutet, Martial; Lathuilière, Cyril; Son Hoang, Hong; Baraille, Rémy

    2015-04-01

    At a regional scale, barotropic tides are the dominant source of variability of currents and water heights. A precise representation of these processes is essential because of their great impacts on human activities (submersion risks, marine renewable energies, ...). Identified sources of error for tide modelling at a regional scale are the followings: bathymetry, boundary forcing and dissipation due to bottom friction. Nevertheless, bathymetric databases are nowadays known with a good accuracy, especially over shelves, and global tide models performances are better than ever. The most promising improvement is thus the bottom friction representation. The method used to estimate bottom friction is the simultaneous perturbation stochastic approximation (SPSA) which consists in the approximation of the gradient based on a fixed number of cost function measurements, regardless of the dimension of the vector to be estimated. Indeed, each cost function measurement is obtained by randomly perturbing every component of the parameter vector. An important feature of SPSA is its relative ease of implementation. In particular, the method does not require the development of tangent linear and adjoint version of the circulation model. Experiments are carried out to estimate bottom friction with the HYbrid Coordinate Ocean Model (HYCOM) in barotropic mode (one isopycnal layer). The study area is the Northeastern Atlantic margin which is characterized by strong currents and an intense dissipation. Bottom friction is parameterized with a quadratic term and friction coefficient is computed with the water height and the bottom roughness. The latter parameter is the one to be estimated. Assimilated data are the available tide gauge observations. First, the bottom roughness is estimated taking into account bottom sediment natures and bathymetric ranges. Then, it is estimated with geographical degrees of freedom. Finally, the impact of the estimation of a mixed quadratic/linear friction

  10. 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

  11. Asbestos free friction composition for brake linings

    Indian Academy of Sciences (India)

    WINTEC

    Abstract. An asbestos free friction material composite for brake linings is synthesized containing fibrous re- inforcing ... every manufacturer of automotive friction materials uses phenolics as ... The resin binder is a critical compo- nent. The limits ...

  12. Friction tensor concept for textured surfaces

    Indian Academy of Sciences (India)

    Directionality of grinding marks influences the coefficient of friction ... Menezes et al (2006a,b) studied the effect of roughness parameters and grinding angle on ... as coefficient of friction, sliding velocity, normal load, hardness and thermal.

  13. Frictional resistance of adiabatic two-phase flow in narrow rectangular duct under rolling conditions

    International Nuclear Information System (INIS)

    Xing, Dianchuan; Yan, Changqi; Sun, Licheng; Jin, Guangyuan; Tan, Sichao

    2013-01-01

    Highlights: ► Two-phase flow frictional resistance in narrow duct in rolling is studied. ► Frictional resistance behaviors in rolling are divided into three regions. ► Transient frictional pressure drop fluctuates synchronously with rolling motion. ► Conventional correlations are evaluated against experimental data in rolling motion. ► New correlation for transient frictional resistance in rolling motion is developed. - Abstract: Frictional resistance of air-water two-phase flow in a narrow rectangular duct subjected to rolling motion was investigated experimentally. Time-averaged and transient frictional pressure drop under rolling condition were compared with conventional correlation in laminar flow region (Re l l ⩽ 1400) and turbulent flow region (Re l > 1400) respectively. The result shows that, despite no influence on time-averaged frictional resistance, rolling motion does induce periodical fluctuation of the pressure drop in laminar and transition flow regions. Transient frictional pressure drop fluctuates synchronously with the rolling motion both in laminar and in transition flow region, while it is nearly invariable in turbulent flow region. The fluctuation amplitude of the Relative frictional pressure gradient decreases with the increasing of the superficial velocities. Lee and Lee (2002) correlation and Chisholm (1967) correlation could satisfactorily predict time-averaged frictional pressure drop under rolling conditions, whereas poorly predict the transient frictional pressure drop when it fluctuates periodically. A new correlation with better accuracy for predicting the transient frictional pressure drop in rolling motion is achieved by modifying the Chisholm (1967) correlation on the basis of analyzing the present experimental results with a great number of data points

  14. Damage Tolerance Assessment of Friction Pull Plug Welds in an Aluminum Alloy

    Science.gov (United States)

    McGill, Preston; Burkholder, Jonathan

    2012-01-01

    Friction stir welding is a solid state welding process used in the fabrication of cryogenic propellant tanks. Self-reacting friction stir welding is one variation of the friction stir weld process being developed for manufacturing tanks. Friction pull plug welding is used to seal the exit hole that remains in a circumferential self-reacting friction stir weld. A friction plug weld placed in a self-reacting friction stir weld results in a non-homogenous weld joint where the initial weld, plug weld, their respective heat affected zones and the base metal all interact. The welded joint is a composite plastically deformed material system with a complex residual stress field. In order to address damage tolerance concerns associated with friction plug welds in safety critical structures, such as propellant tanks, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size. Test data relating residual strength capability to flaw size in an aluminum alloy friction plug weld will be presented.

  15. Available friction of ladder shoes and slip potential for climbing on a straight ladder.

    Science.gov (United States)

    Chang, Wen-Ruey; Chang, Chien-Chi; Matz, Simon

    2005-07-15

    Straight ladder accidents are a major safety problem. As a leading cause of injuries involving straight ladders, slips at the ladder base occur when the required friction exceeds the available friction at the ladder shoe and floor interface. The objectives of this experiment were to measure the available friction at the base of a portable straight ladder in contact with a floor and to estimate the slip potential of the ladder. The results of friction measurements indicated that the measured friction coefficient on the oily surfaces differed among the six commercially available ladder shoes evaluated. A statistical model was used to compare the available friction results from the current study with the friction requirements under different climbing conditions from a previous study based on their stochastic distributions to estimate the slip potential at the base of the ladder. The results showed that different climbing conditions used in the previous study could be supported by available friction on dry surfaces. However, when the ladder was put onto oily surfaces, resulting in a significant reduction in the available friction due to contamination, slip potential was significantly increased.

  16. Effect of solid lubricants on friction and wear behaviour of alloyed ...

    Indian Academy of Sciences (India)

    Friction and wear behaviour of MoS2, boric acid, graphite and TiO2 at four different sliding speeds (1.0, 1.5, 2.0, 2.5 m/s) has been compared with dry sliding condition. MoS2 and graphite show 30 to 50% reduction in mass loss compared to other lubricants at all sliding speeds. Friction coefficient reduces with increase in ...

  17. FEM simulation of a friction testing method based on combined forward conical can-backward straight can extrusion

    DEFF Research Database (Denmark)

    Nakamura, T; Bay, Niels

    1998-01-01

    A new friction testing method based on combined forward conical can-backward straight can extrusion is proposed in order to evaluate friction characteristics in severe metal forming operations. By this method the friction coefficient along the conical punch surface is determined knowing...... the friction coefficient along the die wall. The latter is determined by a combined forward and backward can extrusion of straight cans. Calibration curves determining the relationship between punch travel, can heights, and friction coefficient for the two rests are calculated based on a rigid-plastic FEM...... analysis. Experimental friction tests are carried out in a mechanical press with aluminium alloy A6061 as the workpiece material and different kinds of lubricants. They confirm that the theoretical analysis results irt reasonable values for the friction coefficient....

  18. Fault Frictional Stability in a Nuclear Waste Repository

    Science.gov (United States)

    Orellana, Felipe; Violay, Marie; Scuderi, Marco; Collettini, Cristiano

    2016-04-01

    Exploitation of underground resources induces hydro-mechanical and chemical perturbations in the rock mass. In response to such disturbances, seismic events might occur, affecting the safety of the whole engineering system. The Mont Terri Rock Laboratory is an underground infrastructure devoted to the study of geological disposal of nuclear waste in Switzerland. At the site, it is intersected by large fault zones of about 0.8 - 3 m in thickness and the host rock formation is a shale rock named Opalinus Clay (OPA). The mineralogy of OPA includes a high content of phyllosilicates (50%), quartz (25%), calcite (15%), and smaller proportions of siderite and pyrite. OPA is a stiff, low permeable rock (2×10-18 m2), and its mechanical behaviour is strongly affected by the anisotropy induced by bedding planes. The evaluation of fault stability and associated fault slip behaviour (i.e. seismic vs. aseismic) is a major issue in order to ensure the long-term safety and operation of the repository. Consequently, experiments devoted to understand the frictional behaviour of OPA have been performed in the biaxial apparatus "BRAVA", recently developed at INGV. Simulated fault gouge obtained from intact OPA samples, were deformed at different normal stresses (from 4 to 30 MPa), under dry and fluid-saturated conditions. To estimate the frictional stability, the velocity-dependence of friction was evaluated during velocity steps tests (1-300 μm/s). Slide-hold-slide tests were performed (1-3000 s) to measure the amount of frictional healing. The collected data were subsequently modelled with the Ruina's slip dependent formulation of the rate and state friction constitutive equations. To understand the deformation mechanism, the microstructures of the sheared gouge were analysed. At 7 MPa normal stress and under dry conditions, the friction coefficient decreased from a peak value of μpeak,dry = 0.57 to μss,dry = 0.50. Under fluid-saturated conditions and same normal stress, the

  19. Analytical evaluation on loss of off-side electric power simulation of the High Temperature Engineering Test Reactor

    International Nuclear Information System (INIS)

    Takeda, Takeshi; Nakagawa, Shigeaki; Tachibana, Yukio; Takada, Eiji; Kunitomi, Kazuhiko

    2000-03-01

    A rise-to-power test of the high temperature engineering test reactor (HTTR) started on September 28 in 1999 for establishing and upgrading the technological basis for the high temperature gas-cooled reactor (HTGR). A loss of off-site electric power test of the HTTR from the normal operation under 15 and 30 MW thermal power will be carried out in the rise-to-power test. Analytical evaluations on transient behaviors of the reactor and plant during the loss of off-site electric power were conducted. These estimations are proposed as benchmark problems for the IAEA coordinated research program on 'Evaluation of HTGR Performance'. This report describes an event scenario of transient during the loss of off-site electric power, the outline of major components and system, detailed thermal and nuclear data set for these problems and pre-estimation results of the benchmark problems by an analytical code 'ACCORD' for incore and plant dynamics of the HTGR. (author)

  20. Comparative evaluation of tooth substance loss and its correlation with the abrasivity and chemical composition of different dentifrices.

    Science.gov (United States)

    Singh, Ram Prakash; Sharma, Sidhartha; Logani, Ajay; Shah, Naseem; Singh, Surendra

    2016-01-01

    In India, teeth cleaning with tooth powder is common in rural and semi-urban areas. These dentifrices may contain low-quality abrasives, which may have a deleterious effect on dental hard tissues. This study aims to evaluate the tooth substance loss caused by different dentifrices and to correlate it with chemical composition, size, and shape of abrasives used. An indigenously made automated machine was used for brushing the specimens. Sixty-four freshly extracted premolars were allocated to eight groups (n = 8). Colgate toothpaste was used as the control group. Each specimen was brushed in a vertical motion for 2½ h at 200 strokes/min with a constant applied load of 200 g corresponding to 6-month brushing. The difference in weight (pre- and post-brushing) was determined by an analytical weighing machine. Chemical analysis was done to determine the presence of iron oxide by Inductively Coupled Plasma Mass Spectrometry method. Shape and size of the abrasive particles was evaluated under scanning electron microscopy (SEM). One-way analysis of variance and Paired t-test were used to analyze the data. Tooth substance loss was maximum in the group brushed with red tooth powder, which was shown to contain the highest amount of iron oxide and also exhibited large, irregularly shaped abrasive particles under SEM. Tooth substance loss was documented to be correlated with chemical composition (iron oxide) and the size and shape of abrasive particles used in dentifrices.

  1. 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....

  2. Advances on LuGre friction model

    OpenAIRE

    Fuad, Mohammad; Ikhouane, Fayçal

    2013-01-01

    LuGre friction model is an ordinary differential equation that is widely used in describing the friction phenomenon for mechanical systems. The importance of this model comes from the fact that it captures most of the friction behavior that has been observed including hysteresis. In this paper, we study some aspects related to the hysteresis behavior induced by the LuGre friction model.

  3. 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.

  4. 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 ...

  5. Evaluation of the efficacy of zoledronic acid and amifostine on radiation induced bone loss in mice

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Wook; Lee, Sueum; Kang, Sohi; Moon, Cahng Jong; Kim, Jong Choon; Kim, Sung Ho [College of Veterinary Medicine, Chonnam National University, Gwangju (Korea, Republic of); Jung, Uhee; Jo, Sung Kee [Advanced Radiation Technology Institute, Jeungeup (Korea, Republic of); Jang, Jong Sik [College of Ecology and Environmental Science, Kyungpook National University, Sangju (Korea, Republic of)

    2016-09-15

    This study investigated the effects of zoledronic acid (ZA) on radiation-induced bone loss in C3H/HeN mice. C3H/HeN mice were divided into sham control and three irradiated groups (3 Gy, gamma ray). The irradiated mice were treated for 12 weeks with vehicle, amifostine (intraperitoneal injection), or ZA (subcutaneous injection). Grip strength, uterus weight, and serum alkaline phosphatase (ALP), and tartrate-resistant acid phosphatase (TRAP) levels were measured. Tibiae were analyzed using micro-computed tomography. Treatment of ZA (100 μg·kg{sup -1}·week{sup -1}) significantly preserved trabecular bone volume, trabecular thickness, trabecular number, trabecular separation, bone mineral density of proximal tibia metaphysic, and cortical bone volume, but did not alter the uterus weight of the mice. The administration of ZA for 12 weeks lowered serum ALP and TRAP levels in irradiated mice, suggesting that ZA can reduce the bone turnover rate in mice. No differences were apparent between the amifostine-treated group and the irradiation control group. The results indicate that ZA can prevent radiation-induced bone loss in mice.

  6. Evaluation of Heat Losses Behind the Front of the Detonation Moving Along the Metallic Porous Surface

    Directory of Open Access Journals (Sweden)

    S. V. Golovastov

    2016-01-01

    Full Text Available The paper considers a computational technique of the heat flow from the hot products of detonation combustion into the porous coating and estimates the efficiency of the coating layer that results in slowing the flame front down with disregard the transverse displacement of the combustion products weight of a hydrogen-air mixture.Initial thermodynamic parameters of combustion products on the porous coating surface have been estimated. A drag (stagnation temperature of flow was determined.The statement of task was to calculate the heat flow into the long cylindrical metal fiber with radius of 15 μm. The reference values of heat capacity and heat diffusivity were used to estimate a thermal diffusivity in a wide range of temperatures. An approximation of the parameters is given for a wide range of temperatures.The calculation algorithm using an explicit four-point scheme is presented. The convergence and accuracy of the results were confirmed. The theoretical estimation using cylindrical Bessel functions was made to prove the accuracy of the results.Total heat loss was estimated using the photos of moving detonation front and hot combustion gases.Comparison of the total heat loss and the amount of energy absorbed by a single fiber allowed us to find that the porous coating thickness, resulting in attenuation of detonation wave, is efficient.

  7. Evaluation of Losses Of Cold Energy of Cryogen Products in The Transport Systems

    Science.gov (United States)

    Uglanov, Dmitry; Sarmin, Dmitry; Tsapkova, Alexandra; Burdina, Yana

    2017-12-01

    At present, there are problems of energy saving in various areas of human life and in power complexes of industrial plants. One possible solution to the problem of increasing energy efficiency is the use of liquefied natural gas and its cold energy. Pipelines for fuel or gas supply in cryogen supply systems have different length depending on the mutual position of storage and cryogen consumption devices relatively to a start construction. Cryogen supply and transport systems include a lot of fittings of different assortment. Reservoirs can be installed on different elevation points. To reduce heat inleak and decrease cold energy of cryogen product different kinds of thermal insulation are used. Cryogen pipelines provide required operation conditions of storage and gasifying systems. The aim of the thermal calculation of cryogen transport and supply systems is to define the value of cryogen heat. In this paper it is shown values of cryogen temperature rise due to heat inleaks at cryogen’s transfer along transport systems for ethane, methane, oxygen and nitrogen were calculated. Heat inleaks also due to hydraulic losses were calculated. Specific losses of cold energy of cryogen product for laminar and turbulent flow were calculated. Correspondences of temperature rise, critical pipeline’s length and Reynolds number were defined for nitrogen, argon, methane and oxygen.

  8. Frictional and elastic energy in gecko adhesive detachment.

    Science.gov (United States)

    Gravish, Nick; Wilkinson, Matt; Autumn, Kellar

    2008-03-06

    Geckos use millions of adhesive setae on their toes to climb vertical surfaces at speeds of over 1 m s(-1). Climbing presents a significant challenge for an adhesive since it requires both strong attachment and easy, rapid removal. Conventional pressure-sensitive adhesives are either strong and difficult to remove (e.g. duct tape) or weak and easy to remove (e.g. sticky notes). We discovered that the energy required to detach adhering tokay gecko setae (W(d)) is modulated by the angle (theta) of a linear path of detachment. Gecko setae resist detachment when dragged towards the animal during detachment (theta = 30 degrees ) requiring W(d) = 5.0+/-0.86(s.e.) J m(-2) to detach, largely due to frictional losses. This external frictional loss is analogous to viscous internal frictional losses during detachment of pressure-sensitive adhesives. We found that, remarkably, setae possess a built-in release mechanism. Setae acted as springs when loaded in tension during attachment and returned elastic energy when detached along the optimal path (theta=130 degrees ), resulting in W(d) = -0.8+/-0.12 J m(-2). The release of elastic energy from the setal shaft probably causes spontaneous release, suggesting that curved shafts may enable easy detachment in natural, and synthetic, gecko adhesives.

  9. Friction and dissipative phenomena in quantum mechanics

    International Nuclear Information System (INIS)

    Kostin, M.D.

    1975-01-01

    Frictional and dissipative terms of the Schroedinger equation are studied. A proof is given showing that the frictional term of the Schroedinger--Langevin equation causes the quantum system to lose energy. General expressions are derived for the frictional term of the Schroedinger equation. (U.S.)

  10. Adaptive friction compensation: a globally stable approach

    NARCIS (Netherlands)

    Verbert, K.A.; Tóth, R.; Babuska, R.

    2016-01-01

    In this paper, an adaptive friction compensation scheme is proposed. The friction force is computed as a timevarying friction coefficient multiplied by the sign of the velocity and an on-line update law is designed to estimate this coefficient based on the actual position and velocity errors.

  11. Multiscale friction modeling for sheet metal forming

    NARCIS (Netherlands)

    Hol, J.; Cid Alfaro, M.V.; de Rooij, Matthias B.; Meinders, Vincent T.; Felder, Eric; Montmitonnet, Pierre

    2010-01-01

    The most often used friction model for sheet metal forming simulations is the relative simple Coulomb friction model. This paper presents a more advanced friction model for large scale forming simulations based on the surface change on the micro-scale. The surface texture of a material changes when

  12. A thermodynamic model of sliding friction

    Directory of Open Access Journals (Sweden)

    Lasse Makkonen

    2012-03-01

    Full Text Available A first principles thermodynamic model of sliding friction is derived. The model predictions are in agreement with the observed friction laws both in macro- and nanoscale. When applied to calculating the friction coefficient the model provides a quantitative agreement with recent atomic force microscopy measurements on a number of materials.

  13. 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 ...

  14. Comparative evaluation of sagittal anchorage loss in lingual and labial appliances during space closure: A pilot study

    Directory of Open Access Journals (Sweden)

    Shivanand Venkatesh

    2015-01-01

    Full Text Available Aim: The purpose of this investigation was to assess and compare the anchorage loss between labial and lingual appliance systems during space closure. Materials and Methods: Twenty subjects were part of the study among which 10 subjects (mean age 21 ± 3.6 years were treated using lingual appliance system (0.018" slot-STb™ and 10 subjects (mean age 19 ± 6.1 years were treated using labial preadjusted edgewise appliance system (0.018" slot-MBT™ . First premolar extractions were performed to enable retraction of anterior teeth. Lateral cephalometric radiographs were taken at two intervals, before starting space closure and after space closure that were connoted as T0 and T1 and were analyzed using the method described by Pancherz to measure anchorage loss. Intraclass correlation coefficient (ICC was used to evaluate intraexaminer reliability of the measurements. Student′s t-test was performed to verify any statistical significant correlation between the labial and lingual appliance systems. Statistical differences were determined at the 95% confidence level (P < 0.05. Results: The results showed that all ICC for lingual and labial group were ≥0.90 showing good repeatability of the measurements. Mean anchorage loss of 1.238 ± 0.17 mm in lingual appliance system and an anchorage loss of 2.06 ± 0.39 mm occurred with the labial appliance system. On the comparison between the two appliance systems, lingual appliance demonstrated a significantly lesser anchorage loss than did the labial appliance. Interpretation and Conclusion: This prospective study concludes with the fact that lingual appliance provided better anchorage control than labial appliance during space closure. Use of lingual appliance could be considered in critical anchorage cases when compared with labial appliance.

  15. 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 i...

  16. Improved Coulomb-Friction Damper

    Science.gov (United States)

    Campbell, G. E.

    1985-01-01

    Equal damping provided on forward and reverse strokes. Improved damper has springs and wedge rings symmetrically placed on both ends of piston wedge, so friction force same in both directions of travel. Unlike conventional automotive shock absorbers, they resemble on outside, both versions require no viscous liquid and operate over wide temperature range.

  17. Deformation During Friction Stir Welding

    Science.gov (United States)

    White, Henry J.

    2002-01-01

    Friction Stir Welding (FSW) is a solid state welding process that exhibits characteristics similar to traditional metal cutting processes. The plastic deformation that occurs during friction stir welding is due to the superposition of three flow fields: a primary rotation of a radially symmetric solid plug of metal surrounding the pin tool, a secondary uniform translation, and a tertiary ring vortex flow (smoke rings) surrounding the tool. If the metal sticks to the tool, the plug surface extends down into the metal from the outer edge of the tool shoulder, decreases in diameter like a funnel, and closes up beneath the pin. Since its invention, ten years have gone by and still very little is known about the physics of the friction stir welding process. In this experiment, an H13 steel weld tool (shoulder diameter, 0.797 in; pin diameter, 0.312 in; and pin length, 0.2506 in) was used to weld three 0.255 in thick plates. The deformation behavior during friction stir welding was investigated by metallographically preparing a plan view sections of the weldment and taking Vickers hardness test in the key-hole region.

  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. Microstructure Evolution during Friction Stir Spot Welding of TRIP Steel

    DEFF Research Database (Denmark)

    Lomholt, Trine Colding; Pantleon, Karen; Somers, Marcel A. J.

    2010-01-01

    In this study, the feasibility of friction stir spot welding of TRIP steel is investigated. In addition to manufacturing successful welds, the present study aims at a fundamental understanding of the mechanisms occurring at the (sub)micron scale during friction stir spot welding. As one of the ma...... electron microscopy, and electron backscatter diffraction. Microhardness measurements and lap-shear tensile tests completed the investigations of the welded samples and allow evaluation of the quality of the welds.......In this study, the feasibility of friction stir spot welding of TRIP steel is investigated. In addition to manufacturing successful welds, the present study aims at a fundamental understanding of the mechanisms occurring at the (sub)micron scale during friction stir spot welding. As one of the main...... parameters to control friction stir welding, the influence of the rotational speed of the tool was investigated. Three different rotational speeds (500 rpm, 1000 rpm and 1500 rpm, respectively) were applied. The microstructure of the welded samples was investigated with reflected light microscopy, scanning...

  20. Breakaway frictions of dynamic O-rings in mechanical seals

    Science.gov (United States)

    Lai, Tom; Kay, Peter

    1993-05-01

    Breakaway friction of a dynamic O-ring affects the mechanical seal's response to large axial shaft movement and face wear. However, little data exist to help designers. Therefore, a test rig was developed to measure breakaway friction. The research quantitatively shows the effects of lubrication with silicone grease and a change of surface finish. By using the Taguchi statistical experimental design method, the significance of test parameters was evaluated with a minimum number of tests. It was found that fluid pressure, dwell time, and O-ring percentage squeeze affect O-ring breakaway friction more than the O-ring cross sectional diameter and axial sliding speed within the range of values tested. The authors showed that breakaway friction increased linearly with pressure. However, O-rings made of different materials had significantly different increase rates, even if they had nominally the same durometer hardness. Breakaway friction also increased with logarithm of dwell time. Again, the increase rate depended strongly on the specific O-ring material tested. These observations led the authors to believe that the typical approach of generalizing data based on generic polymer type and durometer was inappropriate.

  1. [Contamination of human milk with aerobic flora: Evaluation of losses for a human milk bank].

    Science.gov (United States)

    Dewitte, C; Courdent, P; Charlet, C; Dumoulin, D; Courcol, R; Pierrat, V

    2015-05-01

    In France, human milk banks pasteurize milk for the mother's own hospitalized baby (personalized milk) and for donation. There is specific legislation regulating the activity of human milk banks with bacterial screening of donor milk before and after pasteurization. Milk should be tested for Staphylococcus aureus and total aerobic flora. Any sample of milk positive for aerobic flora and/or S. aureus before and/or after pasteurization should be discarded. The real pathogenicity of the total aerobic flora is actually debated as well as the usefulness of systematic postpasteurization screening. The aim of this study was to quantify milk losses related to prepasteurization contamination by total aerobic flora in a regional milk bank, to identify losses due to contamination with S. aureus or aerobic flora, and to analyze differences between centers. This was a prospective observational study conducted in the regional human milk bank of the Nord-Pas-de-Calais area in France. Data were collected from six major centers providing 80% of the milk collected between June 2011 and June 2012. Variables were the volumes of personalized milk collected by each center, volumes of contaminated milk, and the type of bacteria identified. During the study period, the regional human milk bank treated 4715 L (liters) of personalized milk and 508 L (10.8%) were discarded due to bacteriological screening. Among these 508 L, 43% were discarded because of a prepasteurization contamination with aerobic flora, 55% because of a prepasteurization contamination with S. aureus, and 2% because of other pathogenic bacteria. Postpasteurization tests were positive in 25 samples (0.5%). Only five of these 25 samples were positive before pasteurization and in all cases with S. aureus. A total of 218 L were destroyed because of prepasteurization contamination with total aerobic flora, while the postpasteurization culture was sterile. There was a great difference between centers in the percentage of

  2. Infrared thermography applied to the evaluation of metabolic heat loss of chicks fed with different energy densities

    Directory of Open Access Journals (Sweden)

    VMOS Ferreira

    2011-06-01

    Full Text Available Brazil must comply with international quality standards and animal welfare requirements in order to maintain its position as world's largest exporter of poultry meat. With the scenario of global climate change there is the forecast of occurrence of extreme events with characteristics of both excess cold and heat for several regions of the country. This study aimed to evaluate the effectiveness of using images of infrared thermography to evaluate the loss of sensible heat in young broilers fed different dietary energy levels. Twenty birds were reared in a house with appropriate brooding using infrared lamps. Birds were distributed in a completely randomized experimental into two treatments: T1 (control diet with 2950 kcal ME/kg-1, and T2 (high-energy diet with 3950 kcal ME/kg-1. Infrared thermographic images of the birds were recorded for four consecutive days. One bird was randomly chosen per treatment, and had special images taken and analyzed. Average surface temperature of the body area was calculated using the surface temperature recorded at 100 spots (50 at the front and 50 at the lateral side of the bird's body. Mean surface temperature of the flock was calculated recording 100 spots on the group of birds. Total radiant heat loss was calculated based on the average data of surface temperature. The results indicated that the young broilers fed the high-energy diet presented a metabolic energy loss equivalent to 0.64 kcal h-1, while the birds fed with the control diet lost 2.18 kcal h-1. This finding confirms that oil supplementation to the diet reduces bird heat loss. The infrared camera was able to record young broilers' surface temperature variation when birds were fed diets with different energy contents.

  3. Coefficient of Friction at the Fingertips in Type II Diabetics Compared to Healthy Adults.

    Science.gov (United States)

    Thames, Beatriz H; Gorniak, Stacey L

    2017-07-01

    Clinical observations suggest that type II diabetes patients are more susceptible to skin changes, which may be associated with reduced coefficient of friction at the fingertips. Reduced coefficient of friction may explain recent reports of fine motor dysfunction in diabetic patients. Coefficient of friction was evaluated using slip force evaluation in a cross-sectional cohort of diabetic patients and age- and sex-matched healthy controls. Covariates of tactile sensation, disease duration, glycated hemoglobin, and clinical diagnosis of peripheral neuropathy were also assessed. A significant decrease in fingertip coefficient of friction in the diabetic group was found as compared to controls. Health state covariates did not alter the strength of between-group differences in statistical analyses. This finding of between-group differences for fingertip frictional properties suggests that causative factors of reported manual motor dysfunction lie in both the distal and proximal portions of the nervous system.

  4. Development of low friction materials for LMFBR components

    International Nuclear Information System (INIS)

    Johnson, R.N.; Aungst, R.C.; Hoffman, N.J.; Cowgill, M.G.; Whitlow, G.A.; Wilson, W.L.

    1976-01-01

    The number of materials capable of providing low friction, low wear, and good corrosion resistance in low-oxygen (less than 1 ppM) sodium at temperatures up to 650 0 C are extremely limited. The paper describes the development, evaluation, and qualification of low-friction materials for this environment with emphasis on chromium carbide base coatings and nickel aluminide diffusion coatings. Design criteria and typical applications in liquid-metal-cooled reactors are described and recommendations offered for conditions under which these materials should and, perhaps more importantly, should not be used. Design parameters required to achieve optimum performance of these materials are discussed

  5. Influence of radiation damage on internal friction background

    International Nuclear Information System (INIS)

    Burbelo, R.M.; Grinik, Eh.U.; Paliokha, M.I.; Orlinskij, A.B.

    1984-01-01

    Influence of radiation damage on internal friction background in samples of polycrystalline nickel and iron irradiated by a fast neutron flux approximately 10 14 neutr/(cm 2 xs) at 350 deg C has been studied using the low-frequency unit of the reverse torsion pendulum type. It has been established experimentally that a high-temperature background of internal friction of iron and nickel samples decreases as accumulating radiation defects occurring under neutron irradiation. Assumptions on a possible mechanism of the effect have been proposed. Simple expression for the background magnitude evaluation has been suggested

  6. Computational evaluation of the constraint loss on the fracture toughness of reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Serrano Garcia, M.

    2007-01-01

    The Master Curve approach is included on the ASME Code through some Code Cases to assess the reactor pressure vessel integrity. However, the margin definition to be added is not defined as is the margin to be added when the Master Curve reference temperature T 0 is obtained by testing pre-cracked Charpy specimens. The reason is that the T 0 value obtained with this specimen geometry is less conservative than the value obtained by testing compact tension specimens possible due to a loss of constraint. The two parameter fracture mechanics, considered as an extension of the classical fracture mechanics, coupled to a micromechanical fracture models is a valuable tool to assess the effect of constraint loss on fracture toughness. The definition of a parameter able to connect the fracture toughens value to the constraint level on the crack tip will allow to quantify margin to be added to the T 0 value when this value is obtained testing the pre-cracked Charpy specimens included in the surveillance capsule of the reactor pressure vessel. The Nuclear Regulatory Commission (NRC) define on the To value obtained by testing compact tension specimens and ben specimens (as pre-cracked Charpy are) bias. the NRC do not approved any of the direct applications of the Master Curve the reactor pressure vessel integrity assessment until this bias will be quantified in a reliable way. the inclusion of the bias on the integrity assessment is done through a margin to be added. In this thesis the bias is demonstrated an quantified empirical and numerically and a generic value is suggested for reactor pressure vessel materials, so that it can be used as a margin to be added to the T 0 value obtained by testing the Charpy specimens included in the surveillance capsules. (Author) 111 ref

  7. Assumptions used for evaluating the potential radiological consequences of a loss of coolant accident for boiling water reactors - June 1974

    International Nuclear Information System (INIS)

    Anon.

    1974-01-01

    Section 50.34 of 10 CFR Part 50 requires that each applicant for a construction permit or operating license provide an analysis and evaluation of the design and performance of structures, systems, and components of the facility with the objective of assessing the risk to public health and safety resulting from operation of the facility. The design basis loss of coolant accident is one of the postulated accidents used to evaluate the adequacy of these structures, systems, and components with respect to the public health and safety. This guide gives acceptable assumptions that may be used in evaluating the radiological consequences of this accident for a pressurized water reactor. In some cases, unusual site characteristics, plant design features, or other factors may require different assumptions which will be considered on an individual case basis. The Advisory Committee on Reactor Safeguards has been consulted concerning this guide and has concurred in the regulatory position

  8. Performance Improvement of Friction Stir Welds by Better Surface Finish

    Science.gov (United States)

    Russell, Sam; Nettles, Mindy

    2015-01-01

    The as-welded friction stir weld has a cross section that may act as a stress concentrator. The geometry associated with the stress concentration may reduce the weld strength and it makes the weld challenging to inspect with ultrasound. In some cases, the geometry leads to false positive nondestructive evaluation (NDE) indications and, in many cases, it requires manual blending to facilitate the inspection. This study will measure the stress concentration effect and develop an improved phased array ultrasound testing (PAUT) technique for friction stir welding. Post-welding, the friction stir weld (FSW) tool would be fitted with an end mill that would machine the weld smooth, trimmed shaved. This would eliminate the need for manual weld preparation for ultrasonic inspections. Manual surface preparation is a hand operation that varies widely depending on the person preparing the welds. Shaving is a process that can be automated and tightly controlled.

  9. Wettability and friction coefficient of micro-magnet arrayed surface

    Science.gov (United States)

    Huang, Wei; Liao, Sijie; Wang, Xiaolei

    2012-01-01

    Surface coating is an important part of surface engineering and it has been successfully used in many applications to improve the performance of surfaces. In this paper, magnetic arrayed films with different thicknesses were fabricated on the surface of 316 stainless steel disks. Controllable colloid - ferrofluids (FF) was chosen as lubricant, which can be adsorbed on the magnetic surface. The wettability of the micro-magnet arrayed surface was evaluated by measuring the contract angle of FF drops on surface. Tribological experiments were carried out to investigate the effects of magnetic film thickness on frictional properties when lubricated by FF under plane contact condition. It was found that the magnetic arrayed surface with thicker magnetic films presented larger contract angle. The frictional test results showed that samples with thicker magnetic films could reduce friction and wear more efficiently at higher sliding velocity under the lubrication of FF.

  10. Friction, slip and structural inhomogeneity of the buried interface

    International Nuclear Information System (INIS)

    Dong, Y; Wu, J; Martini, A; Li, Q

    2011-01-01

    An atomistic model of metallic contacts using realistic interatomic potentials is used to study the connection between friction, slip and the structure of the buried interface. Incommensurability induced by misalignment and lattice mismatch is modeled with contact sizes that are large enough to observe superstructures formed by the relative orientations of the surfaces. The periodicity of the superstructures is quantitatively related to inhomogeneous shear stress distributions in the contact area, and a reduced order model is used to clarify the connection between friction and structural inhomogeneity. Finally, the movement of atoms is evaluated before, during and after slip in both aligned and misaligned contacts to understand how the interfacial structure affects the mechanisms of slip and the corresponding frictional behavior

  11. Defect Detectability Improvement for Conventional Friction Stir Welds

    Science.gov (United States)

    Hill, Chris

    2013-01-01

    This research was conducted to evaluate the effects of defect detectability via phased array ultrasound technology in conventional friction stir welds by comparing conventionally prepped post weld surfaces to a machined surface finish. A machined surface is hypothesized to improve defect detectability and increase material strength.

  12. Frictional drag between quantum wells mediated by phonon exchange

    DEFF Research Database (Denmark)

    Bønsager, M.C.; Flensberg, Karsten; Hu, Ben Yu-Kuang

    1998-01-01

    We use the Kubo formalism to evaluate the contribution of acoustic-phonon exchange to the frictional drag between nearby two-dimensional electron systems. In the case of free phonons, we find a divergent drag rate (tau(D)(-l)). However, tau(D)(-l) becomes finite when phonon scattering from either...

  13. Circuit racing, track texture, temperature and rubber friction

    Science.gov (United States)

    Sharp, R. S.; Gruber, P.; Fina, E.

    2016-04-01

    Some general observations relating to tyre shear forces and road surfaces are followed by more specific considerations from circuit racing. The discussion then focuses on the mechanics of rubber friction. The classical experiments of Grosch are outlined and the interpretations that can be put on them are discussed. The interpretations involve rubber viscoelasticity, so that the vibration properties of rubber need to be considered. Adhesion and deformation mechanisms for energy dissipation at the interface between rubber and road and in the rubber itself are highlighted. The enquiry is concentrated on energy loss by deformation or hysteresis subsequently. Persson's deformation theory is outlined and the material properties necessary to apply the theory to Grosch's experiments are discussed. Predictions of the friction coefficient relating to one particular rubber compound and a rough surface are made using the theory and these are compared with the appropriate results from Grosch. Predictions from Persson's theory of the influence of nominal contact pressure on the friction coefficient are also examined. The extent of the agreement between theory and experiment is discussed. It is concluded that there is value in the theory but that it is far from complete. There is considerable scope for further research on the mechanics of rubber friction.

  14. Interfacial bonding and friction in silicon carbide (filament)-reinforced ceramic- and glass-matrix composites

    International Nuclear Information System (INIS)

    Bright, J.D.; Shetty, D.K.

    1989-01-01

    This paper reports interfacial shear strength and interfacial sliding friction stress assessed in unidirectional SiC-filament-reinforced reaction-bonded silicon nitride (RBSN) and borosilicate glass composites and 0/90 cross-ply reinforced borosilicate glass composite using a fiber pushout test technique. The interface debonding load and the maximum sliding friction load were measured for varying lengths of the embedded fibers by continuously monitoring the load during debonding and pushout of single fibers in finite-thickness specimens. The dependences of the debonding load and the maximum sliding friction load on the initial embedded lengths of the fibers were in agreement with nonlinear shear-lag models. An iterative regression procedure was used to evaluate the interfacial properties, shear debond strength (τ d ), and sliding friction stress (τ f ), from the embedded fiber length dependences of the debonding load and the maximum frictional sliding load, respectively. The shear-lag model and the analysis of sliding friction permit explicit evaluation of a coefficient of sliding friction (μ) and a residual compressive stress on the interface (σ 0 ). The cross-ply composite showed a significantly higher coefficient of interfacial friction as compared to the unidirectional composites

  15. Pressure and Friction Injuries in Primary Care.

    Science.gov (United States)

    Phillips, Shawn; Seiverling, Elizabeth; Silvis, Matthew

    2015-12-01

    Pressure and friction injuries are common throughout the lifespan. A detailed history of the onset and progression of friction and pressure injuries is key to aiding clinicians in determining the underlying mechanism behind the development of the injury. Modifying or removing the forces that are creating pressure or friction is the key to both prevention and healing of these injuries. Proper care of pressure and friction injuries to the skin is important to prevent the development of infection. Patient education on positioning and ergonomics can help to prevent recurrence of pressure and friction injuries. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. 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.

  17. Flat friction tests applied to austenic stainless steels with several surface finish. Analysis of adhesion conditions in friction

    International Nuclear Information System (INIS)

    Coello, J.; Miguel, V.; Ferrer, C.; Calatatyd, A.; Martinez, A.

    2008-01-01

    The main purpose of this work is to evaluate the tribological behaviour of austenic stainless steels AISI 304 with bright surface finishing (B). The assays have been carried out in flat faced dies system with mineral oil of 200 cts viscosity, S 2 Mo grease and in dry conditions. The relationship between friction coefficient and pressure and velocity has been established for the mineral oil as lubricant. In these conditions, a strong adhesive tendency has been found in boundary lubrication regime. The results obtained here, show us that S 2 Mo grease leads to lowest values for the friction coefficient. A minor adhesive behaviour tendency for AISI 316 steel, harder than 304 grades, has been found. A relevant plowing phenomena has been observed for the more critical friction conditions tried out. A surface hardener is produced as a consequence of that. (Author) 19 refs

  18. Generic evaluation of small break loss-of-coolant accident behavior in Babcock and Wilcox designed 177-FA operating plants

    International Nuclear Information System (INIS)

    1980-01-01

    Slow system depressurization resulting from small break loss-of-coolant accidents (LOCAs) in the reactor coolant system have not, until recently, received detailed analytical study comparable to that devoted to large breaks. Following the TMI-2 accident, the staff had a series of meetings with Babcock and Wilcox (B and W) and the B and W licensees. The staff requested that B and W and the licensees: (1) systematically evaluate plant response for small break loss-of-coolant accidents; (2) address each of the concerns documented in the Michelson report; (3) validate the computer codes used against the TMI-2 accident; (4) extend the break spectrum analysis to very small breaks, giving special consideration to failure of pressurizer valves to close; (5) analyze degraded conditions where AFW is not available; (6) prepare design changes aimed at reducing the probability of loss-of-coolant accidents produced by the failure of a PORV to close; and (7) develop revised emergency procedures for small breaks. This report describes the review of the generic analyses performed by B and W based on the requests stated above

  19. Effective tree hazard control on forested recreation sites...losses and protection costs evaluated

    Science.gov (United States)

    Lee A. Paine

    1967-01-01

    Effectiveness of hazard control was evaluated by analyzing data on tree failures, accidents, and control costs on California recreation sites. Results indicate that reduction of limb hazard in oaks and bole hazard in conifers is the most effective form of control. Least effective is limb hazard reduction in conifers. After hazard control goals or control budgets have...

  20. Evaluating the Workload of On-Call Psychiatry Residents: Which Activities Are Associated with Sleep Loss?

    Science.gov (United States)

    Cooke, Brian K.; Cooke, Erinn O.; Sharfstein, Steven S.

    2012-01-01

    Objective: The purpose of this study was to review the workload inventory of on-call psychiatry residents and to evaluate which activities were associated with reductions in on-call sleep. Method: A prospective cohort study was conducted, following 20 psychiatry residents at a 231-bed psychiatry hospital, from July 1, 2008 through June 30, 2009.…

  1. Loss of surface enamel after bracket debonding : An in-vivo and ex-vivo evaluation

    NARCIS (Netherlands)

    Pont, Huib Berghauser; Özcan, Mutlu; Bagis, Bora; Ren, Yijin

    2010-01-01

    INTRODUCTION: The objective of this study was to evaluate the surface enamel after bracket debonding and residual resin removal. METHODS: Thirty patients (female, 20; male, 10; mean age, 18.4 years) who completed orthodontic treatment with fixed appliances (Twin Brackets, 3M Unitek, Monrovia, Calif)

  2. Validation of Friction Models in MARS-MultiD Module with Two-Phase Cross Flow Experiment

    International Nuclear Information System (INIS)

    Choi, Chi-Jin; Yang, Jin-Hwa; Cho, Hyoung-Kyu; Park, Goon-Cher; Euh, Dong-Jin

    2015-01-01

    In the downcomer of Advanced Power Reactor 1400 (APR1400) which has direct vessel injection (DVI) lines as an emergency core cooling system, multidimensional two-phase flow may occur due to the Loss-of-Coolant-Accident (LOCA). The accurate prediction about that is high relevance to evaluation of the integrity of the reactor core. For this reason, Yang performed an experiment that was to investigate the two-dimensional film flow which simulated the two-phase cross flow in the upper downcomer, and obtained the local liquid film velocity and thickness data. From these data, it could be possible to validate the multidimensional modules of system analysis codes. In this study, MARS-MultiD was used to simulate the Yang's experiment, and obtained the local variables. Then, the friction models used in MARS-MultiD were validated by comparing the two-phase flow experimental results with the calculated local variables. In this study, the two-phase cross flow experiment was modeled by the MARS-MultiD. Compared with the experimental results, the calculated results by the code properly presented mass conservation which could be known from the relation between the liquid film velocity and thickness at the same flow rate. The magnitude and direction of the liquid film, however, did not follow well with experimental results. According to the results of Case-2, wall friction should be increased, and interfacial friction should be decreased in MARS-MultiD. These results show that it is needed to modify the friction models in the MARS-MultiD to simulate the two-phase cross flow

  3. Pressure loss coefficient evaluation based on CFD analysis for simple geometries and PWR reactor vessel without geometry simplification

    International Nuclear Information System (INIS)

    Ko II, B.; Park, J. P.; Jeong, J. H.

    2008-01-01

    Nuclear vendors and utilities perform lots of simulations and analyses in order to ensure the safe operation of nuclear power plants (NPPs). In general, the simulations are carried out using vendor-specific design codes and best-estimate system analysis codes and most of them were developed based on 1-dimensional lumped parameter models. These thermal-hydraulic system analysis codes require user input for pressure loss coefficient, k-factor; since they numerically solve Euler-equation. In spite of its high impact on the safety analysis results, there has not been good validation method for the selection of loss coefficient. During the past decade, however; computers, parallel computation methods, and 3-dimensional computational fluid dynamics (CFD) codes have been dramatically enhanced. It is believed to be beneficial to take advantage of advanced commercial CFD codes in safety analysis and design of NPP5. The present work aims to validate pressure loss coefficient evaluation for simple geometries and k-factor calculation for PWR based on CFD. The performances of standard k-ε model, RNG k-ε model, Reynolds stress model (RSM) on the simulation of pressure drop for simple geometry such as, or sudden-expansion, and sudden-contraction are evaluated. The calculated value was compared with pressure loss coefficient in handbook of hydraulic resistance. Then the present work carried out analysis for flow distribution in downcomer and lower plenum of Korean standard nuclear power plants (KSNPs) using STAR-CD. The lower plenum geometry of a PWR is very complicated since there are so many reactor internals, which hinders in CFD analysis for real reactor geometry up to now. The present work takes advantage of 3D CAD model so that real geometry of lower plenum is used. The results give a clear figure about flow fields in the reactor vessel, which is one of major safety concerns. The calculated pressure drop across downcomer and lower plenum appears to be in good agreement

  4. Frictional granular mechanics: A variational approach

    Energy Technology Data Exchange (ETDEWEB)

    Holtzman, R.; Silin, D.B.; Patzek, T.W.

    2009-10-16

    The mechanical properties of a cohesionless granular material are evaluated from grain-scale simulations. Intergranular interactions, including friction and sliding, are modeled by a set of contact rules based on the theories of Hertz, Mindlin, and Deresiewicz. A computer generated, three-dimensional, irregular pack of spherical grains is loaded by incremental displacement of its boundaries. Deformation is described by a sequence of static equilibrium configurations of the pack. A variational approach is employed to find the equilibrium configurations by minimizing the total work against the intergranular loads. Effective elastic moduli are evaluated from the intergranular forces and the deformation of the pack. Good agreement between the computed and measured moduli, achieved with no adjustment of material parameters, establishes the physical soundness of the proposed model.

  5. Usefulness of TrichoScan professional in the evaluation of hair loss in females. Report of 180 cases.

    Science.gov (United States)

    López, V; Martín, J M; Sánchez, R; Ortega, C; Ricart, J M

    2011-09-01

    TrichoScan Professional is a computerized program used for digital measurement of hair growth and hair loss. The aim of our study was to undertake an evaluation with TrichoScan Professional of female patients consulting at our hospitals for hair loss. The purpose of our study was to determine whether TrichoScan was able to identify differences in hair parameters that would correlate with the pattern of alopecia or according to the age of the patients evaluated. One hundred-eighty women that consulted consecutively for loss of hair were included. Patients were aged between 8 and 85 years (mean age 36 years). Data including age, the number of hairs, hair density per square centimetre, anagen and telogen percentage and percentage of terminal and miniaturized hair were analysed. Results observed with TrichoScan were as below: number of hairs (mean 154.9; range 34-316). Hair density per square centimetre (mean 239; range 52-486). Hair in anagen phase (mean 62.4%; range 9-93%). Hair in telogen phase (mean 37.4%; range 7-91%). Terminal hair (mean 95.2%; range 82-100%). Vellus hair (mean 4.7%; range 0-17%). Pearson's correlation test was used to measure the strength of the association of age with the rest of parameters. The statistical analysis showed a significant correlation between age and both the number of hairs and the hair density per square centimetre. However, no significant correlation between age and rest of the parameters was observed. TrichoScan Professional may help to quantify hair density and in our sample, this was the only parameter showing a significant decrease according to age in various types of alopecia affecting the females. © 2010 The Authors. Journal of the European Academy of Dermatology and Venereology © 2010 European Academy of Dermatology and Venereology.

  6. In Vitro Evaluation of the Effect of Tooth Structure Loss on Fracture Resistance of Endodontically Treated Teeth

    Directory of Open Access Journals (Sweden)

    Shirinzad M

    2017-06-01

    Full Text Available Introduction: Since preserving the structure of treated teeth is a critical success factor, studying the effects of tooth structure loss on fracture resistance of the tooth tissue appears necessary. The aim of this study was to evaluate the consequences of the loss of different tissues regarding fracture resistance of teeth undergoing root canal treatment without the use of indirect restorations. Methods :In this experimental study, 70 healthy maxillary first premolar teeth were randomly divided into 7 groups of 10 members, including control group, endodontic access preparation only, MOD cavity preparation, cutting buccal cusp, cutting palatal cusp, cutting buccal cusp and marginal ridge, and cutting the palatal cusp and marginal ridge. The coronal section of teeth was restored incrementally with light cure composite. Finally, samples underwent compressive load with 45˚ angle from each cusp slope in the middle of cusp with an instant speed of 1 mm per min in the Instron machine. Fracture resistance was measured and samples were examined under stereo-microscope to evaluate the mode of failure. Results: The resistance to fracture in root canal treated teeth in different groups in order from first to seventh was 797.13 ± 52.92, 722.50 ± 131.40, 432.15 ± 203.20, 592.66 ± 195.86 124.53 ± 33.09, 85.17 ± 18.45, and 26.03 ± 5.21 Newton. ANOVA test showed statistically significant differences between the groups in terms of their fracture resistance (P = 0.000. Conclusions: The results showed that fracture resistance levels of teeth were significantly affected by amount of their tissue loss. In this study, removal of teeth palatal cusp and marginal ridge had a significant effect on decreasing the fracture resistance, while removing the buccal cusps alone cannot have a significant effect.

  7. Improvement in cavitation erosion resistance of AISI 316L stainless steel by friction stir processing

    Energy Technology Data Exchange (ETDEWEB)

    Hajian, M. [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Abdollah-zadeh, A., E-mail: zadeh@modares.ac.ir [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Rezaei-Nejad, S.S.; Assadi, H. [Department of Materials Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Hadavi, S.M.M. [Department of Materials Science and Engineering, MA University of Technology, Tehran (Iran, Islamic Republic of); Chung, K. [Department of Materials Science and Engineering, Research Institute of Advanced Materials, Engineering Research Institute, Seoul National University, Seoul (Korea, Republic of); Shokouhimehr, M. [Department of Chemical Engineering, College of Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2014-07-01

    Commercial AISI 316L plates with the initial grain size of 14.8 μm were friction stir processed (FSP) with different processing parameters, resulting in two fine-grained microstructures with the grain sizes of 4.6 and 1.7 μm. The cavitation erosion behavior, before and after FSP, was evaluated in terms of incubation time, cumulative mass loss and mean depth of erosion. A separate cavitation erosion test was performed on the transverse cross section of a FSP sample to reveal the effect of grain structure. It was observed that FSP samples, depending on their grain size, are at least 3–6 times more resistant than the base material against cavitation erosion. The improvement in cavitation erosion resistance is attributed to smaller grain structure, lower fraction of twin boundaries, and favorable crystallographic orientation of grains in FSP samples. The finer the grain size, the more cavitation erosion resistance was achieved. Moreover, the microstructures of eroded surfaces were studied using a scanning electron microscope equipped with EBSD, and an atomic force microscope. The mechanisms controlling the cavitation erosion damage in friction stir processed AISI 316L are also discussed.

  8. Surface Modification by Friction Stir Processing of Low-Carbon Steel: Microstructure Investigation and Wear Performance

    Science.gov (United States)

    Sattari, Behnoosh; Shamanian, Morteza; Salimijazi, Farshid; Salehi, Mehdi

    2018-02-01

    A low-carbon steel sheet with a thickness of 5 mm was subjected to friction stir processing (FSP) by one to four different passes. The microstructures of different regions were characterized using the optical microscopy and electron backscatter diffraction. The Vickers micro-harness was measured at the distance of 200 μm below the processed surfaces. The influence of pass numbers (PNs) on wear resistance was studied in terms of coefficients of friction (CoFs), weight losses and wear rates. SEM topographies of the worn surfaces were also studied to evaluate the wear mechanisms. Microstructure observations showed that Widmänstatten ferrite plates were formed in stir zones (SZs) and heat affected zones. As PN increased, these grains were widened due to the increment of the carbon diffusivity and lengthened because of the high heat input and microstructure anisotropy. Besides, increasing the PN causes increasing of the hardness and wear resistance, simultaneously. Specifically, the wear rate in the SZ was reduced from 2.8 × 10-2 mm3 m-1 in base metal to 0.3 × 10-2 mm3 m-1 in sample which was subjected to 4 FSP passes. However, variation in PN had no considerable effect on CoFs. Oxidative wear mechanism was observed on the worn surface of the steel and the FSPed samples while more debris was formed by increasing the PNs.

  9. An evaluation of a weight-loss program incorporating E-learning for obese junior high school students.

    Science.gov (United States)

    Hung, Sheng-Hui; Hwang, Shiow-Li; Su, Mei-Ju; Lue, Shih-Ho; Hsu, Chien-Yeh; Chen, Hsiao-Lien; Chen, Heng-Shuen

    2008-10-01

    Obesity in adolescents is continuing to rise at an alarming rate and is becoming an important public health problem in Taiwan. Therefore, the aims of this study were (1) to evaluate the effectiveness of a Weight-loss E-learning Program (WEP) on obese Chinese adolescents and (2) to gauge this group's satisfaction with the WEP. The design was quasi-experimental, using purposive samples from two junior high schools in Taipei, Taiwan. Obese adolescents between 12 and 14 years of age with body mass indexes (BMI) over 25 kg/m2 were recruited. A 14-week WEP was developed to expedite weight loss for the selected adolescents. Data such as BMI, waist-to-hip ratio, waist circumference, hip circumference, mid-arm circumference, triceps skinfold, blood pressure, and physical fitness were collected through standardized instruments and methods before and after the WEP. The satisfaction of the subjects and four psychosocial variables were evaluated and taken into account by authoritative scales and questionnaires. In total, 37 adolescents participated in this study. After the WEP, we found significant decreases in BMI (p self-esteem scores, p < 0.001 for the other three variables) and satisfaction levels for the WEP ranged from 56.6% to 83.8% in four different criteria. The WEP was effective in helping obese Chinese adolescents lose weight. However, there is still room for improvement.

  10. The Effect of Autologous Activated Platelet Rich Plasma (AA-PRP Injection on Pattern Hair Loss: Clinical and Histomorphometric Evaluation

    Directory of Open Access Journals (Sweden)

    V. Cervelli

    2014-01-01

    Full Text Available To investigate the safety and clinical efficacy of AA-PRP injections for pattern hair loss. AA-PRP, prepared from a small volume of blood, was injected on half of the selected patients’ scalps with pattern hair loss. The other half was treated with placebo. Three treatments were given for each patient, with intervals of 1 month. The endpoints were hair re-growth, hair dystrophy as measured by dermoscopy, burning or itching sensation, and cell proliferation as measured by Ki-67 evaluation. At the end of the 3 cycles of treatment, the patients presented clinical improvement in the mean number of hairs, with a mean increase of 18.0 hairs in the target area, and a mean increase in total hair density of 27.7 ( number of hairs/cm2 compared with baseline values. Microscopic evaluation showed the increase of epidermis thickness and of the number of hair follicles two weeks after the last AA-PRP treatment compared to baseline value (P<0.05. We also observed an increase of Ki67+ keratinocytes of epidermis and of hair follicular bulge cells and a slight increase of small blood vessels around hair follicles in the treated skin compared to baseline (P<0.05.

  11. Friction coefficient and effective interference at the implant-bone interface.

    Science.gov (United States)

    Damm, Niklas B; Morlock, Michael M; Bishop, Nicholas E

    2015-09-18

    Although the contact pressure increases during implantation of a wedge-shaped implant, friction coefficients tend to be measured under constant contact pressure, as endorsed in standard procedures. Abrasion and plastic deformation of the bone during implantation are rarely reported, although they define the effective interference, by reducing the nominal interference between implant and bone cavity. In this study radial forces were analysed during simulated implantation and explantation of angled porous and polished implant surfaces against trabecular bone specimens, to determine the corresponding friction coefficients. Permanent deformation was also analysed to determine the effective interference after implantation. For the most porous surface tested, the friction coefficient initially increased with increasing normal contact stress during implantation and then decreased at higher contact stresses. For a less porous surface, the friction coefficient increased continually with normal contact stress during implantation but did not reach the peak magnitude measured for the rougher surface. Friction coefficients for the polished surface were independent of normal contact stress and much lower than for the porous surfaces. Friction coefficients were slightly lower for pull-out than for push-in for the porous surfaces but not for the polished surface. The effective interference was as little as 30% of the nominal interference for the porous surfaces. The determined variation in friction coefficient with radial contact force, as well as the loss of interference during implantation will enable a more accurate representation of implant press-fitting for simulations. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Friction Reduction Tested for a Downsized Diesel Engine with Low-Viscosity Lubricants Including a Novel Polyalkylene Glycol

    Directory of Open Access Journals (Sweden)

    David E. Sander

    2017-04-01

    Full Text Available With the increasing pressure to reduce emissions, friction reduction is always an up-to-date topic in the automotive industry. Among the various possibilities to reduce mechanical friction, the usage of a low-viscosity lubricant in the engine is one of the most effective and most economic options. Therefore, lubricants of continuously lower viscosity are being developed and offered on the market that promise to reduce engine friction while avoiding deleterious mixed lubrication and wear. In this work, a 1.6 L downsized Diesel engine is used on a highly accurate engine friction test-rig to determine the potential for friction reduction using low viscosity lubricants under realistic operating conditions including high engine loads. In particular, two hydrocarbon-based lubricants, 0W30 and 0W20, are investigated as well as a novel experimental lubricant, which is based on a polyalkylene glycol base stock. Total engine friction is measured for all three lubricants, which show a general 5% advantage for the 0W20 in comparison to the 0W30 lubricant. The polyalkylene glycol-based lubricant, however, shows strongly reduced friction losses, which are about 25% smaller than for the 0W20 lubricant. As the 0W20 and the polyalkylene glycol-based lubricant have the same HTHS-viscosity , the findings contradict the common understanding that the HTHS-viscosity is the dominant driver related to the friction losses.

  13. 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.)

  14. 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

  15. CFD Modeling of Thermal Manikin Heat Loss in a Comfort Evaluation Benchmark Test

    DEFF Research Database (Denmark)

    Nilsson, Håkan O.; Brohus, Henrik; Nielsen, Peter V.

    2007-01-01

    for comfort evaluation. The main idea is to focus on people. It is the comfort requirements of occupants that decide what thermal climate that will prevail. It is therefore important to use comfort simulation methods that originate from people, not just temperatures on surfaces and air.......Computer simulated persons (CSPs) today are different in many ways, reflecting various software possibilities and limitations as well as different research interest. Unfortunately, too few of the theories behind thermal manikin simulations are available in the public domain. Many researchers...

  16. Microstructural evolution in friction stir welding of nanostructured ODS alloys

    International Nuclear Information System (INIS)

    Chen, C.-L.; Tatlock, G.J.; Jones, A.R.

    2010-01-01

    Nanostructured oxide dispersion strengthened (ODS) Fe-based alloys manufactured by mechanical alloying (MA) are generally considered to be promising candidate materials for high-temperature applications up to at least 1100 o C because of their excellent creep strength and good oxidation resistance. However, a key issue with these alloys is the difficulty in using fusion welding techniques to join components due to oxide particle agglomeration and loss in the weld zone and the disruption and discontinuity in the grain structure introduced at the bond. In this study, the evolution of microstructure has been comprehensively studied in friction stir welds in a ferritic ODS alloy. Initially, electron backscattering diffraction (EBSD) was used to analyze the grain orientation, the grain boundary geometries and recrystallization behaviour. It suggested that deformation heterogeneities were introduced during the friction stirring process which facilitated the onset of recrystallization. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) were used to observe the effects of the friction stir welding (FSW) process on the grain structure and the distribution of Y 2 O 3 and other particles in the metal substrates in the FSW and adjacent regions, after the alloys had been recrystallized at temperatures up to 1380 o C for 1 h in air. The results show that fine-equiaxed grains and a uniform distribution of oxide particles were present in the friction stirred region but that the grain boundaries in the parent metal were pinned by particles. Friction stirring appeared to release these boundaries and allowed secondary recrystallization to occur after further heat treatment. The FSW process appears to be a promising technique for joining ferritic ODS alloys in the form of sheet and tube.

  17. Evaluation of Required Water Sources during Extended Loss of All AC Power for CANDU NPPs

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Woo Jae; Lee, Kyung Jin; Kim, Min Ki; Kim, Keon Yeop; Park, Da Hee; Oh, Seo Bin [FNC Technology Co., Yongin (Korea, Republic of); Chang, Young Jin; Byun, Choong Seop [KHNP, Daejeon (Korea, Republic of)

    2016-10-15

    Fukushima accident was caused by lasting long hours of Station Black-Out (SBO) triggered from natural disaster. This accident had resulted in the reactor core damage. The purpose of this study is to evaluate the required water sources to maintain hot standby conditions until 72 hours during ELAP situation. The analysis was performed with CATHENA code. CATHENA code has been developed for the best-estimated transient simulation of CANDU plants. This study was carried out to evaluate the strategy to maintain hot standby conditions during ELAP situation in CANDU reactors. In this analysis, water was supplied to SG by MSSV open and by the gravity feed. It can cool the core without damage until the dousing tank depletion. Before dousing tank depletion, the emergency water supply pump was available by emergency power restoration. The pump continuously fed water to SG. So it is expected that the reactor core can be cooled down without damage for 72 hours if water source is enough to feed. This result is useful to make a strategy against SBO including ELAP situation.

  18. A four-equation friction model for water hammer calculation in quasi-rigid pipelines

    International Nuclear Information System (INIS)

    Ghodhbani, Abdelaziz; Haj Taïeb, Ezzeddine

    2017-01-01

    Friction coupling affects water hammer evolution in pipelines according to the initial flow regime. Unsteady friction models are only validated with uncoupled formulation. On the other hand, coupled models such as four-equation model, provide more accurate prediction of water hammer since fluid-structure interaction (FSI) is taken into account, but they are limited to steady-state friction formulation. This paper deals with the creation of the “four-equation friction model” which is based on the incorporation of the unsteady head loss given by an unsteady friction model into the four-equation model. For transient laminar flow cases, the Zielke model is considered. The proposed model is applied to a quasi-rigid pipe with axial moving valve, and then calculated by the method of characteristics (MOC). Damping and shape of the numerical solution are in good agreement with experimental data. Thus, the proposed model can be incorporated into a new computer code. - Highlights: • Both Zielke model and four-equation model are insufficient to predict water hammer. • The four-equation friction model proposed is obtained by incorporating the unsteady head loss in the four-equation model. • The solution obtained by the proposed model is in good agreement with experimental data. • The wave-speed adjustment scheme is more efficient than interpolations schemes.

  19. 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)

  20. Role of lubricants on friction between self-ligating brackets and archwires.

    Science.gov (United States)

    Leal, Renata C; Amaral, Flávia L B; França, Fabiana M G; Basting, Roberta T; Turssi, Cecilia P

    2014-11-01

    To evaluate the effect of different lubricants on friction between orthodontic brackets and archwires. Active (Quick, Forestadent) and passive (Damon 3MX, Ormco) self-ligating brackets underwent friction tests in the presence of mucin- and carboxymethylcellulose (CMC)-based artificial saliva, distilled water, and whole human saliva (positive control). Dry friction (no lubricant) was used as the negative control. Bracket/wire samples (0.014 × 0.025 inch, CuNiTi, SDS Ormco) underwent friction tests eight times in a universal testing machine. Two-way analysis of variance showed no significant interaction between bracket type and lubricant (P  =  .324). Friction force obtained with passive self-ligating brackets was lower than that for active brackets (P Friction observed in the presence of artificial saliva did not differ from that generated under lubrication with natural human saliva, as shown by Tukey test. Higher friction forces were found with the use of distilled water or when the test was performed under dry condition (ie, with no lubricant). Lubrication plays a role in friction forces between self-ligating brackets and CuNiTi wires, with mucin- and CMC-based artificial saliva providing a reliable alternative to human natural saliva.

  1. Friction behavior of nano-textured polyimide surfaces measured by AFM colloidal probe

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaoliang [College of Equipment Manufacturing, Hebei University of Engineering, Handan 056038 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wu, Chunxia; Che, Hongwei; Hou, Junxian [College of Equipment Manufacturing, Hebei University of Engineering, Handan 056038 (China); Jia, Junhong, E-mail: jhjia@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2014-11-30

    Highlights: • Flat PI film and nano-textured PI film were prepared by spin-coating process. • The nano-textured PI surface has effectively reduced the adhesion and friction. • Friction increased with the increasing of contact area and adhesion. • The growth rate of friction decreased with the increasing of applied load. - Abstract: Flat polyimide (PI) film and silicon dioxide nanoparticle-textured PI film were prepared by means of the spin-coating technique. The adhesion and friction properties of the flat PI surface and nano-textured PI surface were investigated by a series of Atomic force microscope (AFM) colloidal probes. Experimental results revealed that the nano-textured PI surface can significantly reduce the adhesive force and friction force, compared with the flat PI surface. The main reason is that the nano-textures can reduce the contact area between the sample surface and colloidal probe. The effect of colloidal probe size on the friction behavior of the flat and nano-textured PI surfaces was evaluated. The adhesive force and friction force of nano-textured PI surface were increased with the increasing of the size of interacting pairs (AFM colloidal probe) due to the increased contact area. Moreover, the friction forces of flat and nano-textured PI surfaces were increased with applied load and sliding velocity.

  2. Estimation of Road Friction Coefficient in Different Road Conditions Based on Vehicle Braking Dynamics

    Science.gov (United States)

    Zhao, You-Qun; Li, Hai-Qing; Lin, Fen; Wang, Jian; Ji, Xue-Wu

    2017-07-01

    The accurate estimation of road friction coefficient in the active safety control system has become increasingly prominent. Most previous studies on road friction estimation have only used vehicle longitudinal or lateral dynamics and often ignored the load transfer, which tends to cause inaccurate of the actual road friction coefficient. A novel method considering load transfer of front and rear axles is proposed to estimate road friction coefficient based on braking dynamic model of two-wheeled vehicle. Sliding mode control technique is used to build the ideal braking torque controller, which control target is to control the actual wheel slip ratio of front and rear wheels tracking the ideal wheel slip ratio. In order to eliminate the chattering problem of the sliding mode controller, integral switching surface is used to design the sliding mode surface. A second order linear extended state observer is designed to observe road friction coefficient based on wheel speed and braking torque of front and rear wheels. The proposed road friction coefficient estimation schemes are evaluated by simulation in ADAMS/Car. The results show that the estimated values can well agree with the actual values in different road conditions. The observer can estimate road friction coefficient exactly in real-time and resist external disturbance. The proposed research provides a novel method to estimate road friction coefficient with strong robustness and more accurate.

  3. 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

  4. The effect of friction in coulombian damper

    Science.gov (United States)

    Wahad, H. S.; Tudor, A.; Vlase, M.; Cerbu, N.; Subhi, K. A.

    2017-02-01

    The study aimed to analyze the damping phenomenon in a system with variable friction, Stribeck type. Shock absorbers with limit and dry friction, is called coulombian shock-absorbers. The physical damping vibration phenomenon, in equipment, is based on friction between the cushioning gasket and the output regulator of the shock-absorber. Friction between them can be dry, limit, mixture or fluid. The friction is depending on the contact pressure and lubricant presence. It is defined dimensionless form for the Striebeck curve (µ friction coefficient - sliding speed v). The friction may damp a vibratory movement or can maintain it (self-vibration), depending on the µ with v (it can increase / decrease or it can be relative constant). The solutions of differential equation of movement are obtained for some work condition of one damper for automatic washing machine. The friction force can transfer partial or total energy or generates excitation energy in damper. The damping efficiency is defined and is determined analytical for the constant friction coefficient and for the parabolic friction coefficient.

  5. 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.

  6. 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.

  7. Trajectory-dependent energy loss for swift He atoms axially scattered off a silver surface

    Energy Technology Data Exchange (ETDEWEB)

    Ríos Rubiano, C.A. [Instituto de Astronomía y Física del Espacio (CONICET-UBA), Casilla de correo 67, sucursal 28, 1428 Buenos Aires (Argentina); Bocan, G.A. [Centro Atómico Bariloche, Comisión Nacional de Energía Ató mica, and Consejo Nacional de Investigaciones Científicas y Técnicas, S.C. de Bariloche, Río Negro (Argentina); Juaristi, J.I. [Departamento de Física de Materiales, Facultad de Químicas, UPV/EHU, 20018 San Sebastián (Spain); Donostia International Physics Center (DIPC) and Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), 20018 San Sebastián (Spain); Gravielle, M.S., E-mail: msilvia@iafe.uba.ar [Instituto de Astronomía y Física del Espacio (CONICET-UBA), Casilla de correo 67, sucursal 28, 1428 Buenos Aires (Argentina)

    2014-12-01

    Angle- and energy-loss-resolved distributions of helium atoms grazingly scattered from a Ag(110) surface along low indexed crystallographic directions are investigated considering impact energies in the few keV range. Final projectile distributions are evaluated within a semi-classical formalism that includes dissipative effects due to electron–hole excitations through a friction force. For mono-energetic beams impinging along the [11{sup ¯}0],[11{sup ¯}2] and [001] directions, the model predicts the presence of multiple peak structures in energy-loss spectra. Such structures provide detailed information about the trajectory-dependent energy loss. However, when the experimental dispersion of the incident beam is taken into account, these energy-loss peaks are completely washed out, giving rise to a smooth energy-loss distribution, in fairly good agreement with available experimental data.

  8. The Role of Friction Stir Welding in Nuclear Fuel Plate Fabrication

    International Nuclear Information System (INIS)

    Burkes, D.; Medvedev, P.; Chapple, M.; Amritkar, A.; Wells, P.; Charit, I

    2009-01-01

    The friction bonding process combines desirable attributes of both friction stir welding and friction stir processing. The development of the process is spurred on by the need to fabricate thin, high density, reduced enrichment fuel plates for nuclear research reactors. The work seeks to convert research and test reactors currently operating on highly enriched uranium fuel to operate on low enriched uranium fuel without significant loss in reactor performance, safety characteristics, or significant increase in cost. In doing so, the threat of global nuclear material proliferation will be reduced. Feasibility studies performed on the process show that this is a viable option for mass production of plate-type nuclear fuel. Adapting the friction stir weld process for nuclear fuel fabrication has resulted in the development of several unique ideas and observations. Preliminary results of this adaptation and process model development are discussed

  9. Reduced friction in engine sealing system for truck engines; Reibungsreduzierende Motorabdichtung bei Nutzfahrzeugmotoren

    Energy Technology Data Exchange (ETDEWEB)

    Reichert, Joachim [Kaco GmbH und Co. KG, Heilbronn (Germany). RADIA-Dichtsysteme; Schaefer, Peter [Kaco GmbH und Co. KG, Heilbronn (Germany). Nutzfahrzeuganwendungen

    2010-04-15

    The mechanical efficiency of the drive unit components, e.g. the prevention of friction loss, becomes more the focus point of many new developments in engines and drive trains. Radia rotary shaft seal rings as commonly used in utility vehicles cause an accordingly high friction, particularly when in big dimensions. Kaco has engineered a tailor made design of state of the art friction reducing sealing system generation called Fred. In the acronym ''F'' stands for friction and ''red'' stands for reduced. Kaco has defined three focus points of the performance profile from the already established Fred sealing system generation for further engineering when applied in utility vehicles. (orig.)

  10. Friction and Lubrication of Large Tilting-Pad Thrust Bearings

    Directory of Open Access Journals (Sweden)

    Michał Wasilczuk

    2015-04-01

    Full Text Available Fluid film bearings have been extensively used in the industry because of their unbeatable durability and extremely low friction coefficient, despite a very low coefficient of friction dissipation of energy being noticeable, especially in large bearings. Lubricating systems of large tilting pad thrust bearings utilized in large, vertical shaft hydrogenerators are presented in this paper. A large amount of heat is generated due to viscous shearing of the lubricant large tilting pad thrust bearings, and this requires systems for forced cooling of the lubricant. In the dominant bath lubrication systems, cooling is realized by internal coolers or external cooling systems, with the latter showing some important advantages at the cost of complexity and also, potentially, lower reliability. Substantial losses in the bearings, reaching 1 MW in extreme cases, are a good motivation for the research and development aimed at reducing them. Some possible methods and their potential efficiency, along with some effects already documented, are also described in the paper.

  11. Mesotherapy using dutasteride-containing preparation in treatment of female pattern hair loss: photographic, morphometric and ultrustructural evaluation.

    Science.gov (United States)

    Moftah, N; Moftah, N; Abd-Elaziz, G; Ahmed, N; Hamed, Y; Ghannam, B; Ibrahim, M

    2013-06-01

    Treatment of female pattern hair loss (FPHL) is frustrating for both patients and doctors. Mesotherapy is a novel treatment for hair fall and its efficacy in FPHL has not been evaluated. Evaluation of the efficacy and safety of mesotherapy using dutasteride-containing preparation in treatment of FPHL. This study included 126 female patients with FPHL. They were classified into two groups; group I (86 patients) injected with dutasteride-containing preparation and group II (40 control patients) injected with saline. Patients received 12 sessions and were evaluated at the 18th week by: photographic assessment, hair pull test, hair diameter and patient self-assessment. Ultrastructural evaluation was done for three patients. After mesotherapy with dutasteride-containing preparation, photographic improvement occurred in 62.8% of patients compared with 17.5% in control group (P 0.05). Ultrastructural examination of pretreated hairs revealed absent cuticle in one patient and focal destruction of the cuticle in the second patient, which reappeared in both after therapy. We concluded that mesotherapy with dutasteride-containing preparation was effective, tolerable and minimally invasive treatment modality in FPHL with better response for shorter duration of the disease. © 2012 The Authors. Journal of the European Academy of Dermatology and Venereology © 2012 European Academy of Dermatology and Venereology.

  12. Achieving loss of full power capability vs. coasting down -- An economic evaluation

    International Nuclear Information System (INIS)

    Katzmann, R.H.; Palagi, B.B.

    1994-01-01

    Fuel management for nuclear power plants differ from other types of electrical generating stations in a number of ways. Refueling is an infrequent event taking place during planned shutdowns, at intervals of 12, 18, or 24-months. The nuclear fuel is a manufactured product that is custom built for a particular reactor refueling. The new reactor fuel loading must be analyzed to confirm the safety of the new core loading, prior to the plant being returned to service. The fuel manufacturing lead times require specification of the fuel assembly design approximately a year before the actual plant refueling. This places the core fuel management engineer in the role of predicting plant energy output two to three years into the future. At Commonwealth Edison (CECo) present practice is to assume historical average refueling outage lengths and capacity factors, and then to buy sufficient fuel to allow for performance based on historical average. This practice results in the purchase of excess fuel in cycles that under perform average, and power deratings in cycles that over perform average. In this paper, the economic impact of non-average performance is evaluated and an improved fuel ordering methodology is proposed

  13. Evaluation of Soil Loss and Erosion Control Measures on Ranges and Range Structures at Installations in Temperate Climates

    Science.gov (United States)

    2006-06-01

    Soil Loss Equation ( USLE ) and the Revised Universal Soil Loss Equation (RUSLE) continue to be widely accepted methods for estimating sediment loss...range areas. Therefore, a generalized design methodology using the Universal Soil Loss Equation ( USLE ) is presented to accommodate the variations...constructed use the slope most suitable to the area topography (3:1 or 4:1). Step 4: Using the Universal Soil Loss equation, USLE , find the values of A

  14. Weighing the value of memory loss in the surgical evaluation of left temporal lobe epilepsy: a decision analysis.

    Science.gov (United States)

    Akama-Garren, Elliot H; Bianchi, Matt T; Leveroni, Catherine; Cole, Andrew J; Cash, Sydney S; Westover, M Brandon

    2014-11-01

    Anterior temporal lobectomy is curative for many patients with disabling medically refractory temporal lobe epilepsy, but carries an inherent risk of disabling verbal memory loss. Although accurate prediction of iatrogenic memory loss is becoming increasingly possible, it remains unclear how much weight such predictions should have in surgical decision making. Here we aim to create a framework that facilitates a systematic and integrated assessment of the relative risks and benefits of surgery versus medical management for patients with left temporal lobe epilepsy. We constructed a Markov decision model to evaluate the probabilistic outcomes and associated health utilities associated with choosing to undergo a left anterior temporal lobectomy versus continuing with medical management for patients with medically refractory left temporal lobe epilepsy. Three base-cases were considered, representing a spectrum of surgical candidates encountered in practice, with varying degrees of epilepsy-related disability and potential for decreased quality of life in response to post-surgical verbal memory deficits. For patients with moderately severe seizures and moderate risk of verbal memory loss, medical management was the preferred decision, with increased quality-adjusted life expectancy. However, the preferred choice was sensitive to clinically meaningful changes in several parameters, including quality of life impact of verbal memory decline, quality of life with seizures, mortality rate with medical management, probability of remission following surgery, and probability of remission with medical management. Our decision model suggests that for patients with left temporal lobe epilepsy, quantitative assessment of risk and benefit should guide recommendation of therapy. In particular, risk for and potential impact of verbal memory decline should be carefully weighed against the degree of disability conferred by continued seizures on a patient-by-patient basis. Wiley

  15. Development of an Evaluation Methodology for Loss of Large Area Induced from Extreme Events with Malicious Origin

    International Nuclear Information System (INIS)

    Kim, S.C.; Park, J.S.; Chang, D.J.; Kim, D.H.; Lee, S.W.; Lee, Y.J.; Kim, H.W.

    2016-01-01

    Event of loss of large area (LOLA) induced from extreme external event at multi-units nuclear installation has been emerged a new challenges in the realm of nuclear safety and regulation after Fukushima Dai-Ichi accident. The relevant information and experience on evaluation methodology and regulatory requirements are rarely available and negative to share due to the security sensitivity. Most of countries has been prepared their own regulatory requirements and methodologies to evaluate impact of LOLA at nuclear power plant. In Korea, newly amended the Nuclear Safety Acts requires to assess LOLA in terms of EDMG (Extended Damage Mitigation Guideline). Korea Institute of Nuclear Safety (KINS) has performed a pilot research project to develop the methodology and regulatory review guidance on LOLA at multi-units nuclear power plant since 2014. Through this research, we proposed a methodology to identify the strategies for preventive and mitigation of the consequences of LOLA utilizing PSA techniques or its results. The proposed methodology is comprised of 8 steps including policy consideration, threat evaluation, identification of damage path sets, SSCs capacity evaluation and identification of mitigation measures and strategies. The consequence of LOLA due to malevolent aircraft crash may significantly susceptible with analysis assumptions including type of aircraft, amount of residual fuel, and hittable angle and so on, which cannot be shared overtly. This paper introduces a evaluation methodology for LOLA using PSA technique and its results. Also we provide a case study to evaluate hittable access angle using flight simulator for two types of air crafts and to identify potential path sets leading to core damage by affected SSCs within damaged area.(author).

  16. Evaluation of bone loss in antibacterial coated dental implants: An experimental study in dogs

    Energy Technology Data Exchange (ETDEWEB)

    Godoy-Gallardo, Maria [Department of Micro- and Nanotechnology, Technical University of Denmark, Kongens Lyngby (Denmark); Manzanares-Céspedes, Maria Cristina [Unidad de Anatomía y Embriología Humana, Faculty of Dentistry, University of Barcelona, Barcelona (Spain); Sevilla, Pablo [Department of Mechanics, Escola Universitària Salesiana de Sarrià (EUSS), Barcelona (Spain); Nart, José [Department of Periodontology, School of Dentistry, Universitat Internacional de Catalunya, Sant Cugat (Spain); Manzanares, Norberto [Unidad de Anatomía y Embriología Humana, Faculty of Dentistry, University of Barcelona, Barcelona (Spain); Manero, José M. [Biomaterials, Biomechanics and Tissue Engineering Group, Dept. Materials Science and Metallurgical Engineering, Technical University of Catalonia (UPC-BarcelonaTECH), Barcelona (Spain); Centre for Research in NanoEngineering (CRNE), UPC-BarcelonaTECH, Barcelona (Spain); Gil, Francisco Javier [Universitat Internacional de Catalunya, Sant Cugat (Spain); Boyd, Steven K. [McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, Alberta (Canada); Rodríguez, Daniel, E-mail: daniel.rodriguez.rius@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Dept. Materials Science and Metallurgical Engineering, Technical University of Catalonia (UPC-BarcelonaTECH), Barcelona (Spain); Centre for Research in NanoEngineering (CRNE), UPC-BarcelonaTECH, Barcelona (Spain)

    2016-12-01

    The aim of this study was to evaluate the in vivo effect of antibacterial modified dental implants in the first stages of peri-implantitis. Thirty dental implants were inserted in the mandibular premolar sites of 5 beagle dogs. Sites were randomly assigned to Ti (untreated implants, 10 units), Ti-Ag (silver electrodeposition treatment, 10 units), and Ti-TSP (silanization treatment, 10 units). Coated implants were characterized by scanning electron microscopy, interferometry and X-ray photoelectron spectroscopy. Two months after implant insertion, experimental peri-implantitis was initiated by ligature placement. Ligatures were removed 2 months later, and plaque formation was allowed for 2 additional months. Clinical and radiographic analyses were performed during the study. Implant-tissue samples were prepared for micro computed tomography, backscattered scanning electron microscopy, histomorphometric and histological analyses and ion release measurements. X-ray, SEM and histology images showed that vertical bone resorption in treated implants was lower than in the control group (P < 0.05). This effect is likely due to the capacity of the treatments to reduce bacteria colonization on the implant surface. Histological analysis suggested an increase of peri-implant bone formation on silanized implants. However, the short post-ligature period was not enough to detect differences in clinical parameters among implant groups. Within the limits of this study, antibacterial surface treatments have a positive effect against bone resorption induced by peri-implantitis. - Highlights: • Dental implants were modified with two antibacterial treatments, silver and TESPSA silanization. • Performance of the modified dental implants was studied in vivo. • Treated implants showed less peri-implant bone resorption. • Decrease in bone resorption was attributed to the antibacterial surface treatments. • Silane treatment enhanced bone regeneration around dental implants.

  17. Evaluation of bone loss in antibacterial coated dental implants: An experimental study in dogs

    International Nuclear Information System (INIS)

    Godoy-Gallardo, Maria; Manzanares-Céspedes, Maria Cristina; Sevilla, Pablo; Nart, José; Manzanares, Norberto; Manero, José M.; Gil, Francisco Javier; Boyd, Steven K.; Rodríguez, Daniel

    2016-01-01

    The aim of this study was to evaluate the in vivo effect of antibacterial modified dental implants in the first stages of peri-implantitis. Thirty dental implants were inserted in the mandibular premolar sites of 5 beagle dogs. Sites were randomly assigned to Ti (untreated implants, 10 units), Ti-Ag (silver electrodeposition treatment, 10 units), and Ti-TSP (silanization treatment, 10 units). Coated implants were characterized by scanning electron microscopy, interferometry and X-ray photoelectron spectroscopy. Two months after implant insertion, experimental peri-implantitis was initiated by ligature placement. Ligatures were removed 2 months later, and plaque formation was allowed for 2 additional months. Clinical and radiographic analyses were performed during the study. Implant-tissue samples were prepared for micro computed tomography, backscattered scanning electron microscopy, histomorphometric and histological analyses and ion release measurements. X-ray, SEM and histology images showed that vertical bone resorption in treated implants was lower than in the control group (P < 0.05). This effect is likely due to the capacity of the treatments to reduce bacteria colonization on the implant surface. Histological analysis suggested an increase of peri-implant bone formation on silanized implants. However, the short post-ligature period was not enough to detect differences in clinical parameters among implant groups. Within the limits of this study, antibacterial surface treatments have a positive effect against bone resorption induced by peri-implantitis. - Highlights: • Dental implants were modified with two antibacterial treatments, silver and TESPSA silanization. • Performance of the modified dental implants was studied in vivo. • Treated implants showed less peri-implant bone resorption. • Decrease in bone resorption was attributed to the antibacterial surface treatments. • Silane treatment enhanced bone regeneration around dental implants.

  18. A Monte Carlo computer code for evaluating energy loss of 10 keV to 10 MeV ions in amorphous silicon materials

    International Nuclear Information System (INIS)

    Erramli, H.; Elbounagui, O.; Misdaq, M.A.; Merzouki, A.

    2007-01-01

    The basic concepts of a computer simulation code for determining the energy loss of ions in the 10 keV to 10 MeV energy range in amorphous silicon materials were presented and discussed. Data obtained were found in good agreement with those obtained by using a SRIM programme. Electronic and nuclear energy losses were evaluated. Variation of the energy loss as a function of the incident ion energy were studied. This new computer code is a good tool for evaluating stopping powers of various materials for light and heavy ions

  19. Effect of friction time on mechanical and metallurgical properties of continuous drive friction welded Ti6Al4V/SUS321 joints

    International Nuclear Information System (INIS)

    Li, Peng; Li, Jinglong; Salman, Muhammad; Liang, Li; Xiong, Jiangtao; Zhang, Fusheng

    2014-01-01

    Highlights: • The effect of friction time on the microstructure and joint strength was studied. • The fit of burn-off lengths at different times yields a simple equation. • The longer friction time leads to oversized flash in Ti6Al4V side and overgrown IMCs. • An IMZ with width less than 3 μm is beneficial to make a strong metallurgical bond. • The average strength of 560 MPa is obtained and higher than ever reported results. - Abstract: Dissimilar joint of Ti6Al4V titanium alloy and SUS321 stainless steel was fabricated by continuous drive friction welding. The effect of friction time on the mechanical properties was evaluated by hardness measurement and tensile test, while the interfacial microstructure and fracture morphologies were analyzed by scanning electron microscope, energy dispersive spectroscope and X-ray Diffraction. The results show that the tensile strength increases with friction time under the experimental conditions. And the maximum average strength 560 MPa, which is 90.3% of the SUS321 base metal, is achieved at a friction time of 4 s. For all samples, studied fracture occurred along the joint interface, where intermetallic compounds like FeTi, Fe 2 Ti, Ni 3 (Al, Ti) and Fe 3 Ti 3 O and many other phases were formed among elements from the two base metals. The width of intermetallic compounds zone increases with friction time up to 3 μm, below which it is beneficial to make a strong metallurgical bond. However, the longer friction time leads to oversized flash on the Ti6Al4V side and overgrown intermetallic compounds. Finally the optimized friction time was discussed to be in the range of 2–4 s, under which the sound joint with good reproducibility can be expected

  20. 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. PMID:23934227