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Sample records for cylindrical grinding operation

  1. Surface waviness resulting from single point diamond dressing in cylindrical grinding

    SciTech Connect

    Redmond, J.; Hinnerichs, T.; Apodaca, E.

    1996-05-01

    This paper describes an experimental investigation of workpiece surface waviness that stems from poor single point diamond wheel dressing procedures in cylindrical grinding. If done improperly, single point dressing can produce a thread on the grinding wheel surface that is then imposed on the workpiece during machining. The circumferential waviness exhibited by the threaded workpiece is similar to that resulting from one per rev vibrations of the grinding wheel. In order to differentiate between these two sources of waviness, a geometrical approach to predicting the circumferential and axial waves produced during grinding is presented. The concepts presented are illustrated through a series of plunge grinding tests incorporating dressing procedures of varying quality. Test results verify that dressing induced circumferential waviness is similar to waviness resulting from one per rev type vibrations of the grinding wheel. The two sources can be distinguished, however, through examination of the workpiece waviness in the axial direction.

  2. Learning Activity Packets for Grinding Machines. Unit III--Cylindrical Grinding.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This learning activity packet (LAP) is one of three that accompany the curriculum guide on grinding machines. It outlines the study activities and performance tasks for the third unit of this curriculum guide. Its purpose is to aid the student in attaining a working knowledge of this area of training and in achieving a skilled or moderately…

  3. Optimization of the dressing parameters in cylindrical grinding based on a generalized utility function

    NASA Astrophysics Data System (ADS)

    Aleksandrova, Irina

    2016-01-01

    The existing studies, concerning the dressing process, focus on the major influence of the dressing conditions on the grinding response variables. However, the choice of the dressing conditions is often made, based on the experience of the qualified staff or using data from reference books. The optimal dressing parameters, which are only valid for the particular methods and dressing and grinding conditions, are also used. The paper presents a methodology for optimization of the dressing parameters in cylindrical grinding. The generalized utility function has been chosen as an optimization parameter. It is a complex indicator determining the economic, dynamic and manufacturing characteristics of the grinding process. The developed methodology is implemented for the dressing of aluminium oxide grinding wheels by using experimental diamond roller dressers with different grit sizes made of medium- and high-strength synthetic diamonds type ??32 and ??80. To solve the optimization problem, a model of the generalized utility function is created which reflects the complex impact of dressing parameters. The model is built based on the results from the conducted complex study and modeling of the grinding wheel lifetime, cutting ability, production rate and cutting forces during grinding. They are closely related to the dressing conditions (dressing speed ratio, radial in-feed of the diamond roller dresser and dress-out time), the diamond roller dresser grit size/grinding wheel grit size ratio, the type of synthetic diamonds and the direction of dressing. Some dressing parameters are determined for which the generalized utility function has a maximum and which guarantee an optimum combination of the following: the lifetime and cutting ability of the abrasive wheels, the tangential cutting force magnitude and the production rate of the grinding process. The results obtained prove the possibility of control and optimization of grinding by selecting particular dressing

  4. 30 CFR 56.15014 - Eye protection when operating grinding wheels.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Eye protection when operating grinding wheels. 56.15014 Section 56.15014 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... MINES Personal Protection § 56.15014 Eye protection when operating grinding wheels. Face shields...

  5. 30 CFR 56.15014 - Eye protection when operating grinding wheels.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Eye protection when operating grinding wheels. 56.15014 Section 56.15014 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... MINES Personal Protection § 56.15014 Eye protection when operating grinding wheels. Face shields...

  6. 30 CFR 56.15014 - Eye protection when operating grinding wheels.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Eye protection when operating grinding wheels. 56.15014 Section 56.15014 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... MINES Personal Protection § 56.15014 Eye protection when operating grinding wheels. Face shields...

  7. 30 CFR 56.15014 - Eye protection when operating grinding wheels.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Eye protection when operating grinding wheels. 56.15014 Section 56.15014 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... MINES Personal Protection § 56.15014 Eye protection when operating grinding wheels. Face shields...

  8. 30 CFR 56.15014 - Eye protection when operating grinding wheels.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Eye protection when operating grinding wheels. 56.15014 Section 56.15014 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... MINES Personal Protection § 56.15014 Eye protection when operating grinding wheels. Face shields...

  9. Measurements of air concentrations of thorium during grinding and welding operations using thoriated tungsten electrodes

    SciTech Connect

    Crim, E.M.; Bradley, T.D.

    1995-05-01

    An evaluation was performed to determine whether thorium was present in concentrations above the derived air concentration during grinding and welding operations using thoriated tungsten electrodes. A few of the advantages of using thoriated tungsten electrodes in industry include easier arc starting, greater stability, and reduced weld metal contamination. The electrodes used in this evaluation contained 2% thoria (thorium oxide) and were either 2.4 mm or 3.9 mm in diameter. Personal breathing zone and area air samples were collected for the experienced welders participating in this evaluation during grinding operations. The results during the grinding operations for personal and area air samples were generally below the derived air concentration (DAC) for {sup 232}Th for solubility class Y of 0.04 Bq m{sup -3} (1 x 10 {sup -12} {mu}Ci mL{sup -1}) as per 10 CFR 20. The area samples collected during welding operations were below the DAC.

  10. 30 CFR 57.15014 - Eye protection when operating grinding wheels.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Eye protection when operating grinding wheels. 57.15014 Section 57.15014 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... NONMETAL MINES Personal Protection Surface and Underground § 57.15014 Eye protection when...

  11. 30 CFR 57.15014 - Eye protection when operating grinding wheels.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Eye protection when operating grinding wheels. 57.15014 Section 57.15014 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... NONMETAL MINES Personal Protection Surface and Underground § 57.15014 Eye protection when...

  12. 30 CFR 57.15014 - Eye protection when operating grinding wheels.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Eye protection when operating grinding wheels. 57.15014 Section 57.15014 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... NONMETAL MINES Personal Protection Surface and Underground § 57.15014 Eye protection when...

  13. 30 CFR 57.15014 - Eye protection when operating grinding wheels.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Eye protection when operating grinding wheels. 57.15014 Section 57.15014 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... NONMETAL MINES Personal Protection Surface and Underground § 57.15014 Eye protection when...

  14. 30 CFR 57.15014 - Eye protection when operating grinding wheels.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Eye protection when operating grinding wheels. 57.15014 Section 57.15014 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... NONMETAL MINES Personal Protection Surface and Underground § 57.15014 Eye protection when...

  15. Compressible sleeve provides automatic centering for grinding or turning of cylinders

    NASA Technical Reports Server (NTRS)

    Rohrer, J. A.

    1968-01-01

    Elastomeric sleeve supported on a threaded mandrel automatically centers cylindrical castings for grinding or turning. By expanding the diameter of the sleeve with pressure against the ends, the casting becomes rigidly supported and the surfacing operation can be completed.

  16. Tool grinding machine

    DOEpatents

    Dial, Sr., Charles E.

    1980-01-01

    The present invention relates to an improved tool grinding mechanism for grinding single point diamond cutting tools to precise roundness and radius specifications. The present invention utilizes a tool holder which is longitudinally displaced with respect to the remainder of the grinding system due to contact of the tool with the grinding surface with this displacement being monitored so that any variation in the grinding of the cutting surface such as caused by crystal orientation or tool thickness may be compensated for during the grinding operation to assure the attainment of the desired cutting tool face specifications.

  17. Improved tool grinding machine

    DOEpatents

    Dial, C.E. Sr.

    The present invention relates to an improved tool grinding mechanism for grinding single point diamond cutting tools to precise roundness and radius specifications. The present invention utilizes a tool holder which is longitudinally displaced with respect to the remainder of the grinding system due to contact of the tool with the grinding surface with this displacement being monitored so that any variation in the grinding of the cutting surface such as caused by crystal orientation or tool thicknesses may be compensated for during the grinding operation to assure the attainment of the desired cutting tool face specifications.

  18. Effects of High Pressure ORE Grinding on the Efficiency of Flotation Operations

    NASA Astrophysics Data System (ADS)

    Saramak, Daniel; Krawczykowska, Aldona; Młynarczykowska, Anna

    2014-10-01

    This article discusses issues related to the impact of the high pressure comminution process on the efficiency of the copper ore flotation operations. HPGR technology improves the efficiency of mineral resource enrichment through a better liberation of useful components from waste rock as well as more efficient comminution of the material. Research programme included the run of a laboratory flotation process for HPGR crushing products at different levels of operating pressures and moisture content. The test results showed that products of the high-pressure grinding rolls achieved better recoveries in flotation processes and showed a higher grade of useful components in the flotation concentrate, in comparison to the ball mill products. Upgrading curves have also been marked in the following arrangement: the content of useful component in concentrate the floatation recovery. All upgrading curves for HPGR products had a more favourable course in comparison to the curves of conventionally grinded ore. The results also indicate that various values of flotation recoveries have been obtained depending on the machine operating parameters (i.e. the operating pressure), and selected feed properties (moisture).

  19. Force characteristics in continuous path controlled crankpin grinding

    NASA Astrophysics Data System (ADS)

    Zhang, Manchao; Yao, Zhenqiang

    2015-03-01

    Recent research on the grinding force involved in cylindrical plunge grinding has focused mainly on steady-state conditions. Unlike in conventional external cylindrical plunge grinding, the conditions between the grinding wheel and the crankpin change periodically in path controlled grinding because of the eccentricity of the crankpin and the constant rotational speed of the crankshaft. The objective of this study is to investigate the effects of various grinding conditions on the characteristics of the grinding force during continuous path controlled grinding. Path controlled plunge grinding is conducted at a constant rotational speed using a cubic boron nitride (CBN) wheel. The grinding force is determined by measuring the torque. The experimental results show that the force and torque vary sinusoidally during dry grinding and load grinding. The variations in the results reveal that the resultant grinding force and torque decrease with higher grinding speeds and increase with higher peripheral speeds of the pin and higher grinding depths. In path controlled grinding, unlike in conventional external cylindrical plunge grinding, the axial grinding force cannot be disregarded. The speeds and speed ratios of the workpiece and wheel are also analyzed, and the analysis results show that up-grinding and down-grinding occur during the grinding process. This paper proposes a method for describing the force behavior under varied process conditions during continuous path controlled grinding, which provides a beneficial reference for describing the material removal mechanism and for optimizing continuous controlled crankpin grinding.

  20. Operational characteristics and plasma measurements in cylindrical Hall thrusters

    SciTech Connect

    Shirasaki, Atsushi; Tahara, Hirokazu

    2007-04-01

    The cylindrical Hall thruster (CHT) is an attractive approach to achieve a long lifetime thruster operation especially in low power space applications. Because of the larger volume-to-surface ratio than conventional coaxial Hall thrusters, the cylindrical Hall thrusters are characterized by a reduced heating of the thruster parts and potential lower erosion. Existing CHTs can feature a short coaxial channel in order to sustain a high ionization in the thruster discharge. A 5.6 cm diameter cylindrical Hall thruster was developed and operated with and without a short coaxial region of the thruster channel, in the power range of 70-300 W. It is shown that the CHT without coaxial region can operate stable and achieve higher thrust efficiency, 22%-32% more than that with a coaxial region. Plasma probe measurements inside the thruster channel and ion energy measurements in the plasma plume suggest that the ionization/acceleration region in the CHT is located near the anode region where a radial magnetic field is stronger.

  1. Combined Grinding and Drying of Biomass in One Operation Phase I

    SciTech Connect

    Sokhansanj, S

    2008-06-26

    First American Scientific Corporation (FASC) has developed a unique and innovative grinder/dryer called KDS Micronex. The KS (Kinetic Disintegration System) combines two operations of grinding and drying into a single operation which reduces dependence on external heat input. The machine captures the heat of comminution and combines it will centrifugal forces to expedite moisture extraction from wet biomass. Because it uses mechanical forces rather than providing direct heat to perform the drying operation, it is a simpler machine and uses less energy than conventional grinding and drying operations which occur as two separate steps. The entire compact unit can be transported on a flatbed trailer to the site where biomass is available. Hence, the KDS Micronex is a technology that enables inexpensive pretreatment of waste materials and biomass. A well prepared biomass can be used as feed, fuel or fertilizer instead of being discarded. Electricity and chemical feedstock produced from such biomass would displace the use of fossil fuels and no net greenhouse gas emissions would result from such bio-based operations. Organic fertilizers resulting from the KS Micronex grinding/drying process will be pathogen-free unlike raw animal manures. The feasibility tests on KS during Phase I showed that a prototype machine can be developed, field tested and the technology demonstrated for commercial applications. The present KDS machine can remove up to 400 kg/h of water from a wet feed material. Since biomass processors demand a finished product that is only 10% moist and most raw materials like corn stover, bagasse, layer manure, cow dung, and waste wood have moisture contents of the order of 50%, this water removal rate translates to a production rate of roughly half a ton per hour. this is too small for most processors who are unwilling to acquire multiple machines because of the added complexity to the feed and product removal systems. The economics suffer due to small

  2. Performing in-feed type centerless grinding process on a surface grinder

    SciTech Connect

    Xu, W.; Wu, Y.; Sato, T.; Lin, W.

    2011-01-17

    In our previous study, a new centerless grinding method using surface grinder was proposed. In this method, centerless grinding operations are performed by installing a compact centerless grinding unit, consisting mainly of an ultrasonic elliptic-vibration shoe, a blade and their respective holders, on the worktable of a surface grinder. During grinding, the cylindrical workpiece is held on the ultrasonic shoe and the blade, and its rotational motion is controlled by the elliptic motion of the shoe end-face. An actual unit had been produced and its performance in tangential-feed type centerless grinding using a surface grinder had been confirmed in the previous workd. In this paper, the performance of the grinding unit in in-feed centerless grinding operation was confirmed, and the effects of the main process parameter, i.e., eccentric angle, on the workpiece roundness was investigated experimentally. The obtained results showed that: (1) the centerless grinding unit performed well in in-feed type centerless grinding; (2) the eccentric angle affects roundness significantly, and its optimal angle is 6 deg.; (3) the workpiece roundness can be further improved by varying the eccentric angle during grinding, and the final roundness reached 0.65 {mu}m after grinding as the eccentric angle varied from 9 deg. to 6 deg. and to 3 deg.

  3. A Guide for Developing Standard Operating Job Procedures for the Screening & Grinding Process Wastewater Treatment Facility. SOJP No. 1.

    ERIC Educational Resources Information Center

    Deal, Gerald A.; Montgomery, James A.

    This guide describes standard operating job procedures for the screening and grinding process of wastewater treatment facilities. The objective of this process is the removal of coarse materials from the raw waste stream for the protection of subsequent equipment and processes. The guide gives step-by-step instructions for safety inspection,…

  4. Forecasting of operational indicators of grinding tools with the controlled form and orientation of abrasive grains

    NASA Astrophysics Data System (ADS)

    Korotkov, V. A.; Minkin, E. M.

    2015-09-01

    rational angle of grain orientation for cutting disc are in range Θ=65°÷75°. The joint analysis of dependences of front angles and tension in grains from factors of their form and orientation allows the prediction of operating characteristics of grinding tools at the design stage for specific tasks and processing conditions.

  5. Crush Grinding

    SciTech Connect

    T. Q. Nguyen

    2005-04-01

    Crush Grinding is a special process used at the Kansas City Plant to finish stem sections of reservoir products. In this process, a precise profile of the desired product is formed on a tungsten carbide roll. This roll slowly transfers a mirror image of the profile onto the grinding surface of a wheel. The transfer rate of the profile is between 0.001 and 0.010 inches per minute. Crush grinding is desirable since it provides consistent surface finishes and thin walls at a high production rate. In addition, it generates very sharp fillet radii. However, crush grinding is a complex process since many variables affect the final product. Therefore, the process requires more attention and knowledge beyond basic metal removal practices. While the Kansas City Plant began using these machines in 1995, a formal study regarding crush grinding has not been conducted there. In addition, very little literature is available in the grinding industry regarding this process. As a result, new engineers at the Kansas City Plant must learn the process through trial and error. The purpose of this document is to address this literature deficit while specifically promoting a better understanding of the stem crush grinding process at the Kansas City Plant.

  6. Innovative grinding wheel design for cost-effective machining of advanced ceramics

    SciTech Connect

    Licht, R.H.; Kuo, P.; Liu, S.; Murphy, D.; Picone, J.W.; Ramanath, S.

    2000-05-01

    This Final Report covers the Phase II Innovative Grinding Wheel (IGW) program in which Norton Company successfully developed a novel grinding wheel for cost-effective cylindrical grinding of advanced ceramics. In 1995, Norton Company successfully completed the 16-month Phase I technical effort to define requirements, design, develop, and evaluate a next-generation grinding wheel for cost-effective cylindrical grinding of advanced ceramics using small prototype wheels. The Phase II program was initiated to scale-up the new superabrasive wheel specification to larger diameters, 305-mm to 406-mm, required for most production grinding of cylindrical ceramic parts, and to perform in-house and independent validation grinding tests.

  7. The method of assessment of the grinding wheel cutting ability in the plunge grinding

    NASA Astrophysics Data System (ADS)

    Nadolny, Krzysztof

    2012-09-01

    This article presents the method of comparative assessment of the grinding wheel cutting ability in the plunge grinding kinematics. A new method has been developed to facilitate multicriterial assessment of the working conditions of the abrasive grains and the bond bridges, as well as the wear mechanisms of the GWAS, which occur during the grinding process, with simultaneous limitation of the workshop tests range. The work hereby describes the methodology of assessment of the grinding wheel cutting ability in a short grinding test that lasts for 3 seconds, for example, with a specially shaped grinding wheel, in plunge grinding. The grinding wheel macrogeometry modification applied in the developed method consists in forming a cone or a few zones of various diameters on its surface in the dressing cut. It presents an exemplary application of two variants of the method in the internal cylindrical plunge grinding, in 100Cr6 steel. Grinding wheels with microcrystalline corundum grains and ceramic bond underwent assessment. Analysis of the registered machining results showed greater efficacy of the method of cutting using a grinding wheel with zones of various diameters. The method allows for comparative tests upon different grinding wheels, with various grinding parameters and different machined materials.

  8. Grinding away

    SciTech Connect

    Korz, T.

    2009-03-15

    Coal preparation in gasification plants is all too often neglected. The coal gasification industry has experienced enormous growth over the last few years and consequently the demand of coal grinding and drying has also increased. The design and development of coal mills has taken great strides since the first coal grinding plant was delivered to an IGCC power plant in Buggenum, Netherlands. The article describes a typical flow sheet for a coal gasification plant with a possibility of feeding the mill with different types of materials besides coal. 5 figs.

  9. Standard Operating Procedure for the Grinding and Extraction of Lead in Paint using Nitric Acid and a Rotor/Stator System Powered by a High Speed Motor

    EPA Science Inventory

    This Standard Operating Procedure (SOP) describes a new, rapid, and relatively inexpensive one step procedure which grinds the paint samples removed from the substrate and simultaneously quantitatively extracts the Pb from the paint in only one step in preparation for quantitativ...

  10. Grinding assembly, grinding apparatus, weld joint defect repair system, and methods

    DOEpatents

    Larsen, Eric D.; Watkins, Arthur D.; Bitsoi, Rodney J.; Pace, David P.

    2005-09-27

    A grinding assembly for grinding a weld joint of a workpiece includes a grinder apparatus, a grinder apparatus includes a grinding wheel configured to grind the weld joint, a member configured to receive the grinding wheel, the member being configured to be removably attached to the grinder apparatus, and a sensor assembly configured to detect a contact between the grinding wheel and the workpiece. The grinding assembly also includes a processing circuitry in communication with the grinder apparatus and configured to control operations of the grinder apparatus, the processing circuitry configured to receive weld defect information of the weld joint from an inspection assembly to create a contour grinding profile to grind the weld joint in a predetermined shape based on the received weld defect information, and a manipulator having an end configured to carry the grinder apparatus, the manipulator further configured to operate in multiple dimensions.

  11. Apparatus for and method of operating a cylindrical pulsed induction mass launcher

    DOEpatents

    Cowan, Jr., Maynard; Duggin, Billy W.; Widner, Melvin M.

    1992-01-01

    An electromagnetic cylindrical projectile mass launcher and a method of operation is provided which includes a cylindrical projectile having a conducting armature, a cylindrical barrel in which the armature is received, a plurality of electromagnetic drive coil stages, a plurality of pulse energy sources, and a pulsed power arrangement for generating magnetic pulses forming a pulsed magnetic wave along the length of the launcher barrel. The pulsed magnetic wave provides a propelling force on the projectile along the drive coil. The pulsed magnetic wave of the drive coil stages is advanced along the armature faster than the projectile to thereby generate an induced current wave in the armature. The pulsed generation of the magnetic wave minimizes electromagnetic heating of the projectile and provides for smooth acceleration of the projectile through the barrel of the launcher.

  12. Apparatus for and method of operating a cylindrical pulsed induction mass launcher

    DOEpatents

    Cowan, M. Jr.; Duggin, B.W.; Widner, M.M.

    1992-06-30

    An electromagnetic cylindrical projectile mass launcher and a method of operation is provided which includes a cylindrical projectile having a conducting armature, a cylindrical barrel in which the armature is received, a plurality of electromagnetic drive coil stages, a plurality of pulse energy sources, and a pulsed power arrangement for generating magnetic pulses forming a pulsed magnetic wave along the length of the launcher barrel. The pulsed magnetic wave provides a propelling force on the projectile along the drive coil. The pulsed magnetic wave of the drive coil stages is advanced along the armature faster than the projectile to thereby generate an induced current wave in the armature. The pulsed generation of the magnetic wave minimizes electromagnetic heating of the projectile and provides for smooth acceleration of the projectile through the barrel of the launcher. 2 figs.

  13. Method for grinding precision components

    DOEpatents

    Ramanath, Srinivasan; Kuo, Shih Yee; Williston, William H.; Buljan, Sergej-Tomislav

    2000-01-01

    A method for precision cylindrical grinding of hard brittle materials, such as ceramics or glass and composites comprising ceramics or glass, provides material removal rates as high as 19-380 cm.sup.3 /min/cm. The abrasive tools used in the method comprise a strong, light weight wheel core bonded to a continuous rim of abrasive segments containing superabrasive grain in a dense metal bond matrix.

  14. Modelling of dynamic contact length in rail grinding process

    NASA Astrophysics Data System (ADS)

    Zhi, Shaodan; Li, Jianyong; Zarembski, A. M.

    2014-09-01

    Rails endure frequent dynamic loads from the passing trains for supporting trains and guiding wheels. The accumulated stress concentrations will cause the plastic deformation of rail towards generating corrugations, contact fatigue cracks and also other defects, resulting in more dangerous status even the derailment risks. So the rail grinding technology has been invented with rotating grinding stones pressed on the rail with defects removal. Such rail grinding works are directed by experiences rather than scientifically guidance, lacking of flexible and scientific operating methods. With grinding control unit holding the grinding stones, the rail grinding process has the characteristics not only the surface grinding but also the running railway vehicles. First of all, it's important to analyze the contact length between the grinding stone and the rail, because the contact length is a critical parameter to measure the grinding capabilities of stones. Moreover, it's needed to build up models of railway vehicle unit bonded with the grinding stone to represent the rail grinding car. Therefore the theoretical model for contact length is developed based on the geometrical analysis. And the calculating models are improved considering the grinding car's dynamic behaviors during the grinding process. Eventually, results are obtained based on the models by taking both the operation parameters and the structure parameters into the calculation, which are suitable for revealing the process of rail grinding by combining the grinding mechanism and the railway vehicle systems.

  15. Visual enhancements in pick-and-place tasks: Human operators controlling a simulated cylindrical manipulator

    NASA Technical Reports Server (NTRS)

    Kim, Won S.; Tendick, Frank; Stark, Lawrence

    1989-01-01

    A teleoperation simulator was constructed with vector display system, joysticks, and a simulated cylindrical manipulator, in order to quantitatively evaluate various display conditions. The first of two experiments conducted investigated the effects of perspective parameter variations on human operators' pick-and-place performance, using a monoscopic perspective display. The second experiment involved visual enhancements of the monoscopic perspective display, by adding a grid and reference lines, by comparison with visual enhancements of a stereoscopic display; results indicate that stereoscopy generally permits superior pick-and-place performance, but that monoscopy nevertheless allows equivalent performance when defined with appropriate perspective parameter values and adequate visual enhancements.

  16. Visual enhancements in pick-and-place tasks - Human operators controlling a simulated cylindrical manipulator

    NASA Technical Reports Server (NTRS)

    Kim, Won S.; Tendick, Frank; Stark, Lawrence W.

    1987-01-01

    A teleoperation simulator has been constructed with vector display system, joysticks, and a simulated cylindrical manipulator, in order to quantitatively evaluate various display conditions. The first of two experiments thus conducted investigated the effects of perspective parameter variations on human operators' pick-and-place performance, using a monoscopic perspective display. The second experiment involved visual enhancements of the monoscopic perspective display, by adding a grid and reference lines, by comparison with visual enhancements of a stereoscopic display; results indicate that stereoscopy generally permits superior pick-and-place performance, but that monoscopy nevertheless allows equivalent performance when defined with appropriate perspective parameter values and adequate visual enhancements.

  17. Operation characteristics of cylindrical miniature grooved heat pipe using aqueous CuO nanofluids

    SciTech Connect

    Wang, Guo-Shan; Song, Bin; Liu, Zhen-Hua

    2010-11-15

    An experimental study was performed to investigate the operation characteristics of a cylindrical miniature grooved heat pipe using aqueous CuO nanofluid as the working fluid at some steady cooling conditions. The experiments were carried out under both the steady operation process and the unsteady startup process. The experiment results show that substituting the nanofluid for water as the working fluid can apparently improve the thermal performance of the heat pipe for steady operation. The total heat resistance and the maximum heat removal capacity of the heat pipe using nanofluids can maximally reduce by 50% and increase by 40% compared with that of the heat pipe using water, respectively. For unsteady startup process, substituting the nanofluid for water as the working fluid, cannot only improve the thermal performance, but also reduce significantly the startup time. (author)

  18. Wire Electrical Discharge Truing of Metal Bond Diamond Grinding Wheels

    SciTech Connect

    McSpadden, SB

    2002-01-24

    Cylindrical wire EDM profile truing of the metal bond diamond wheel for precision form grinding of ceramics is presented in this report. First a corrosion-resistant, precise spindle with the high-electrical current capability for wire EDM truing of grinding wheel was fabricated. An arc profile was adopted in order to determine form tolerances capabilities of this process. Results show the wire EDM process can generate {micro}m-scale precision form on the diamond wheel efficiently. The wheel, after truing, was used to grind silicon nitride. Grinding forces, surface finish of ground components, and wheel wear were measured. The EDM trued wheel showed a reduction in grinding force from that of the stick dressed wheel. Surface finishes between the two truing methods were similar. In the beginning of the grinding, significant wheel wear rate was identified. The subsequent wheel wear rate stabilized and became considerably lower.

  19. Grinding Parts For Automatic Welding

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.; Hoult, William S.

    1989-01-01

    Rollers guide grinding tool along prospective welding path. Skatelike fixture holds rotary grinder or file for machining large-diameter rings or ring segments in preparation for welding. Operator grasps handles to push rolling fixture along part. Rollers maintain precise dimensional relationship so grinding wheel cuts precise depth. Fixture-mounted grinder machines surface to quality sufficient for automatic welding; manual welding with attendant variations and distortion not necessary. Developed to enable automatic welding of parts, manual welding of which resulted in weld bead permeated with microscopic fissures.

  20. Conduit grinding apparatus

    DOEpatents

    Nachbar, Henry D.; Korytkowski, Alfred S.

    1991-01-01

    A grinding apparatus for grinding the interior portion of a valve stem receiving area of a valve. The apparatus comprises a faceplate, a plurality of cams mounted to an interior face of the faceplate, a locking bolt to lock the faceplate at a predetermined position on the valve, a movable grinder and a guide tube for positioning an optical viewer proximate the area to be grinded. The apparatus can either be rotated about the valve for grinding an area of the inner diameter of a valve stem receiving area or locked at a predetermined position to grind a specific point in the receiving area.

  1. The Effect of Cutting Speed in Metallic Glass Grinding

    SciTech Connect

    Serbest, Erdinc; Bakkal, Mustafa; Karipcin, Ilker; Derin, Bora

    2011-01-17

    In this paper, the effects of the cutting speed in metallic glass grinding were investigated in dry conditions. The results showed that grinding forces decrease as grinding energy increase with the increasing cutting speeds. The present investigations on ground surface and grinding chips morphologies -shows that material removal and surface formation of the BMG are mainly due to the ductile chip deformation and ploughing as well as brittle fracture of some particles from the edges of the tracks. The roughness values obtained with the Cubic Boron Nitride wheels are acceptable for the grinding operation.

  2. Development of massproductive ultraprecision grinding technology for brittle material devices

    SciTech Connect

    Kanai, A.; Miyashita, M.; Daito, M.

    1996-12-31

    Experimental results from an ultaprecision, centerless grinding system are reported. The system is designed for ductile mode grinding of brittle material devices on a mass production scale. A postprocess work diameter measuring stand was used with the high stiffness grinding machine.Size error correction was shown to be practically applicable as a mass production ultraprecision ferrule grinding technology. The key items were determined to be: (1) force-operated positioning servo system of slide on plain bearing guideways, (2) measurement of relative motion between grinding and regulating wheels with differential linear encoder, (3) application of linear encoder stability, and (4) application of microtruing technology to wheels.

  3. Design and Operating Characteristics of High-Speed, Small-Bore Cylindrical-Roller Bearings

    NASA Technical Reports Server (NTRS)

    Pinel, Stanley, I.; Signer, Hans R.; Zaretsky, Erwin V.

    2000-01-01

    The computer program SHABERTH was used to analyze 35-mm-bore cylindrical roller bearings designed and manufactured for high-speed turbomachinery applications. Parametric tests of the bearings were conducted on a high-speed, high-temperature bearing tester and the results were compared with the computer predictions. Bearings with a channeled inner ring were lubricated through the inner ring, while bearings with a channeled outer ring were lubricated with oil jets. Tests were run with and without outer-ring cooling. The predicted bearing life decreased with increasing speed because of increased contact stresses caused by centrifugal load. Lower temperatures, less roller skidding, and lower power losses were obtained with channeled inner rings. Power losses calculated by the SHABERTH computer program correlated reasonably well with the test results. The Parker formula for XCAV (used in SHABERTH as a measure of oil volume in the bearing cavity) needed to be adjusted to reflect the prevailing operating conditions. The XCAV formula will need to be further refined to reflect roller bearing lubrication, ring design, cage design, and location of the cage-controlling land.

  4. Grinding Away Microfissures

    NASA Technical Reports Server (NTRS)

    Booth, Gary N.; Malinzak, R. Michael

    1990-01-01

    Treatment similar to dental polishing used to remove microfissures from metal parts without reworking adjacent surfaces. Any variety of abrasive tips attached to small motor used to grind spot treated. Configuration of grinding head must be compatible with configurations of motor and workpiece. Devised to eliminate spurious marks on welded parts.

  5. Grinding Wheel System

    DOEpatents

    Malkin, Stephen; Gao, Robert; Guo, Changsheng; Varghese, Biju; Pathare, Sumukh

    2006-01-10

    A grinding wheel system includes a grinding wheel with at least one embedded sensor. The system also includes an adapter disk containing electronics that process signals produced by each embedded sensor and that transmits sensor information to a data processing platform for further processing of the transmitted information.

  6. Grinding Wheel System

    DOEpatents

    Malkin, Stephen; Gao, Robert; Guo, Changsheng; Varghese, Biju; Pathare, Sumukh

    2003-08-05

    A grinding wheel system includes a grinding wheel with at least one embedded sensor. The system also includes an adapter disk containing electronics that process signals produced by each embedded sensor and that transmits sensor information to a data processing platform for further processing of the transmitted information.

  7. Use of in-process EDM truing to generate complex contours on metal-bond, superabrasive grinding wheels for precision grinding structural ceramics

    SciTech Connect

    Piscotty, M. A., LLNL

    1997-08-01

    This paper presents recent work performed at Lawrence Livermore National Laboratory to develop cost-effective, versatile and robust manufacturing methods for grinding precision features in structural ceramics using metal-bond, superabrasive grinding wheels. The developed processes include utilizing specialized, on-machine hardware to generate precision profiles onto grinding wheels using electrical-discharge machining (EDM) and a contoured rotating electrode. The production grinding processes are described, which were developed and used to grind various precision details into a host of structural ceramics such as Al{sub 2}O{sub 3}, Si{sub 3}N{sub 4}, and BeO. The methodologies, hardware and results of both creep-feed and cylindrical grinding are described. A discussion of imparted grinding damage and wheel wear is also presented.

  8. Crystalline silica dust and respirable particulate matter during indoor concrete grinding - wet grinding and ventilated grinding compared with uncontrolled conventional grinding.

    PubMed

    Akbar-Khanzadeh, Farhang; Milz, Sheryl; Ames, April; Susi, Pamela P; Bisesi, Michael; Khuder, Sadik A; Akbar-Khanzadeh, Mahboubeh

    2007-10-01

    The effectiveness of wet grinding (wet dust reduction method) and ventilated grinding (local exhaust ventilation method, LEV) in reducing the levels of respirable crystalline silica dust (quartz) and respirable suspended particulate matter (RSP) were compared with that of uncontrolled (no dust reduction method) conventional grinding. A field laboratory was set up to simulate concrete surface grinding using hand-held angle grinders in an enclosed workplace. A total of 34 personal samples (16 pairs side-by-side and 2 singles) and 5 background air samples were collected during 18 concrete grinding sessions ranging from 15-93 min. General ventilation had no statistically significant effect on operator's exposure to dust. Overall, the arithmetic mean concentrations of respirable crystalline silica dust and RSP in personal air samples during: (i) five sessions of uncontrolled conventional grinding were respectively 61.7 and 611 mg/m(3) (ii) seven sessions of wet grinding were 0.896 and 11.9 mg/m(3) and (iii) six sessions of LEV grinding were 0.155 and 1.99 mg/m(3). Uncontrolled conventional grinding generated relatively high levels of respirable silica dust and proportionally high levels of RSP. Wet grinding was effective in reducing the geometric mean concentrations of respirable silica dust 98.2% and RSP 97.6%. LEV grinding was even more effective and reduced the geometric mean concentrations of respirable silica dust 99.7% and RSP 99.6%. Nevertheless, the average level of respirable silica dust (i) during wet grinding was 0.959 mg/m(3) (38 times the American Conference of Governmental Industrial Hygienists [ACGIH] threshold limit value [TLV] of 0.025 mg/m(3)) and (ii) during LEV grinding was 0.155 mg/m(3) (6 times the ACGIH TLV). Further studies are needed to examine the effectiveness of a greater variety of models, types, and sizes of grinders on different types of cement in different positions and also to test the simulated field lab experimentation in the field

  9. Bearing restoration by grinding

    NASA Technical Reports Server (NTRS)

    Hanau, H.; Parker, R. J.; Zaretsky, E. V.; Chen, S. M.; Bull, H. L.

    1976-01-01

    A joint program was undertaken by the NASA Lewis Research Center and the Army Aviation Systems Command to restore by grinding those rolling-element bearings which are currently being discarded at aircraft engine and transmission overhaul. Three bearing types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. No bearing failures occurred related to the restoration by grinding process. The risk and cost of a bearing restoration by grinding programs was analyzed. A microeconomic impact analysis was performed.

  10. Classifier mills for coal grinding and drying

    SciTech Connect

    Galk, J.; Peukert, W.

    1995-12-31

    This report presents a special air classifier mill for coal grinding. Air classifier mills use the two fundamental process steps grinding and classifying in one machine. An essential advantage is the independent operation of grinding rotor speed and classifier rotor speed. This offers good control of the produced particle size distribution and great flexibility in process control. Using an air classifier mill for grinding coal followed by direct injection into the firing chamber allows for good control of burnout. Another advantage is that drying of coal can take place as a parallel step by heating process air passing through the classifier mill. In this report an air classifier mill, some typical process data, possible throughput, and an industrial application are shown.

  11. Vitreous bond CBN high speed and high material removal rate grinding of ceramics

    SciTech Connect

    Shih, A.J.; Grant, M.B.; Yonushonis, T.M.; Morris, T.O.; McSpadden, S.B.

    1998-08-01

    High speed (up to 127 m/s) and high material removal rate (up to 10 mm{sup 3}/s/mm) grinding experiments using a vitreous bond CBN wheel were conducted to investigate the effects of material removal rate, wheel speed, dwell time and truing speed ratio on cylindrical grinding of silicon nitride and zirconia. Experimental results show that the high grinding wheel surface speed can reduce the effective chip thickness, lower grinding forces, enable high material removal rate grinding and achieve a higher G-ratio. The radial feed rate was increased to as high as 0.34 {micro}m/s for zirconia and 0.25 {micro}m/s for silicon nitride grinding to explore the advantage of using high wheel speed for cost-effective high material removal rate grinding of ceramics.

  12. Ultra-fine grinding of coal

    SciTech Connect

    Wang Shoulu; Wang Xinguo; Gao Ying

    1997-12-31

    Clean coal is known by its low ash content. Most coals contain a large amount of ash, some of which are finely distributed in the coal matrix. With the conventional cleaning process, such ash can not be removed efficiently. From existing coal preparation plants, much middling and high-ash slime come out as by-products and are used only as inferior fuel. Beijing Graduate School, China University of Mining and Technology, has developed a process for deep-cleaning of coal. This process includes ultra-fine grinding of coal to liberate the locked ash minerals followed by efficient separation with selective coagulation-flotation. With this process, concentrate can be extracted from inferior coal or ultra-clean coal can be obtained from conventional concentrate. Tumbling and vibrating ball mills are conventional for general grinding. However, for ultra-fine grinding they are inefficient and consume much more power. This paper gives some aspects of an ultra-fine grinding mill developed by Beijing Graduate School. The Ultra-Fine Grinding Mill is a JMI series wet grinding mill, and consists of a static horizontal closed tube with a rotor inside. The rotor assembly includes: a horizontal shaft, two vaned disks being fixed apart at the shaft, and longitudinal bar deflectors fixed across the disks. Sufficient clearance is allowed between the disk and end plates of the tube and between the disk rim and tube wall. This configuration enables free passage of grinding medium and pulp within the mill. While the mill is in operation, four principal movements of grinding medium and pulp are created: inward radially by deflectors, oppositely axial by vanes, tangential by rotation, and vibrating due to vortices behind the deflectors.

  13. A quadrupole ion trap with cylindrical geometry operated in the mass-selective instability mode.

    PubMed

    Wells, J M; Badman, E R; Cooks, R G

    1998-02-01

    A cylindrical geometry ion trap is used to record mass spectra in the mass-selective instability mode. The geometry of the cylindrical ion trap has been optimized to maximize the quadrupole field component relative to the higher-order field content through field calculations using the Poisson/Superfish code and through experimental variation of the electrode structure. The results correspond well with predictions of the calculations. The trap has been used to record mass spectra with better than unit mass resolution, high sensitivity, and a mass/charge range of ∼600 Th. Multistage (MS(3)) experiments have been performed, and the Mathieu stability region has been experimentally mapped. The performance of this device compares satisfactorily with that of the hyperbolic ion trap. PMID:21644742

  14. 36. INTERIOR VIEW, NORTON GRINDER, TYPES USED TO GRIND ROUGH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    36. INTERIOR VIEW, NORTON GRINDER, TYPE-S USED TO GRIND ROUGH EDGES OFF THE FORGED TOOLS; NOTE OPERATOR IS FINISH GRINDING BLADE END OF A POST HOLE DIGGER AND TAMPING BAR - Warwood Tool Company, Foot of Nineteenth Street, Wheeling, Ohio County, WV

  15. Grinding kinetics and equilibrium states

    NASA Technical Reports Server (NTRS)

    Opoczky, L.; Farnady, F.

    1984-01-01

    The temporary and permanent equilibrium occurring during the initial stage of cement grinding does not indicate the end of comminution, but rather an increased energy consumption during grinding. The constant dynamic equilibrium occurs after a long grinding period indicating the end of comminution for a given particle size. Grinding equilibrium curves can be constructed to show the stages of comminution and agglomeration for certain particle sizes.

  16. Electro-chemical grinding

    NASA Technical Reports Server (NTRS)

    Feagans, P. L.

    1972-01-01

    Electro-chemical grinding technique has rotation speed control, constant feed rates, and contour control. Hypersonic engine parts of nickel alloys can be almost 100% machined, keeping tool pressure at virtual zero. Technique eliminates galling and permits constant surface finish and burr-free interrupted cutting.

  17. Grinding Wheel Profile

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This graphic dubbed by engineers as the 'Grinding Wheel Profile' is the detective's tool used by the Opportunity team to help them understand one of the processes that formed the interior of a rock called 'McKittrick.' Scientists are looking for clues as to how layers, grains and minerals helped create this rock, and the engineers who built the rock abrasion tool (RAT) wanted to ensure that their instrument's handiwork did not get confused with natural processes.

    In the original microscopic image underlaying the graphics, engineers and scientists noticed 'layers' or 'scratches' on the spherical object nicknamed 'blueberry' in the lower right part of the image. The designers of the rock abrasion tool noticed that the arc length and width of the scratches were similar to the shape and size of the rock abrasion tool's grinding wheel, which is made out of a pad of diamond teeth.

    The scrapes on the bottom right blueberry appear to be caused by the fact that the berry got dislodged slightly and its surface was scraped with the grinding pad. In this image, the largest yellow circle is the overall diameter of the hole ground by the rock abrasion tool and the largest yellow rectangular shape is the area of the grinding wheel bit. The smaller yellow semi-circle is the path that the center of the grinding tool follows. The orange arrow arcing around the solid yellow circle (center of grinding tool) indicates the direction that the grinding tool spins around its own center at 3,000 revolutions per minute. The tool simultaneously spins in an orbit around the center of the hole, indicated by the larger orange arrow to the left.

    The grinding tool is 22 millimeters (0.9 inches) in length and the actual grinding surface, which consists of the diamond pad, is 1.5 millimeters (0.06 inches) in length, indicated by the two smaller rectangles. You can see that the smaller bottom rectangle fits exactly the width of the scrape marks.

    The grooves on the blueberry are also the

  18. The influence of grinding oil viscosity on grinding heat and burn damage in creep-feed grinding{copyright}

    SciTech Connect

    Zhen-Change Liu; Abe, Satoshi; Noda, Masahiro

    1995-08-01

    Grinding oils are widely used in precision grinding, such as tool grinding, thread grinding and gear grinding, during which processes grinding burn is the most prevalent damage affecting the integrity of ground surface. This paper discusses the influence of oil viscosity on grinding heat and burn damage in creep-feed-grinding. Experimental results indicated that, under lighter grinding conditions, the effects of oil viscosity was not observed, but under heavy grinding conditions grinding burn occurred when using low viscosity oil. When the viscosity of the oil was increased, grinding heat and burn damage tended to be reduced. As the viscosity was increased to a certain level, grinding burn reduction, by further increasing the viscosity, became less while other problems such as much higher oil pump noise and reduced oil flow occurred. It is clear that a viscosity limit exists for given grinding conditions. 5 refs., 4 figs., 3 tabs.

  19. Medical insurance claims and surveillance for occupational disease: analysis of respiratory, cardiac, and cancer outcomes in auto industry tool grinding operations.

    PubMed

    Park, R M

    2001-04-01

    To evaluate medical insurance claims for chronic disease investigation, claims from eight automotive machining plants (1984 to 1993) were linked with work histories (1967 to 1993), and associations with respiratory, cardiac, and cancer conditions were investigated, in a case-control design analyzed with logistic regression. The primary focus was tool grinding, but other important processes examined were metal-working, welding, forging, heat treat, engine testing, and diverse-skilled trades work. Considerable variability in claim-derived incidence rates across plants was not explained by age or known exposure differences. Asthma incidence increased in tool grinding (at mean cumulative duration: odds ratio [OR], 3.0; 95% confidence interval [CI], 0.90 to 10.0), as did non-ischemic heart disease (cardiomyopathy, cor pulmonale, rheumatic heart disease, or hypertension; OR, 3.1; 95% CI, 1.26 to 7.6). These trends appeared in models with deficits (OR < 1.0) for those ever exposed to tool grinding because of exposure-response miss-specification, demographic confounding, or removal of high-risk workers from the exposed group. The apparent cancer rates identified from claims greatly exceeded the expected rates from a cancer registry, suggesting that diagnostic, "rule-out," and surveillance functions were contributing. This study supports the epidemiologic use of medical insurance records in surveillance and, possibly, etiologic investigation and identifies issues requiring special attention or resolution. PMID:11322094

  20. Grinding machine: friend or foe.

    PubMed

    Adigun, I A; Kuranga, S A; Abdulrahman, L O

    2002-01-01

    Few cases of traumatic loses of the external genitalia have been reported in this part of the world. In a developing country like ours, grinding machines are commonly being used by the people for domestic purposes. Children in their mid fifteens are usually employed to man and operate the machine without proper training and apprenticeship. Many of them have fallen victims of various genito-urinary injuries from grinding machine. Treating a child for complete traumatic loss of penis is rare and challenging any where in the world. A 12 years old boy presented to the emergency unit of our hospital with penile amputation 18 hours after the injury was sustained. A penile reconstruction of corporal cavernosa phalloplasty was used. This method of reconstruction may be used by clinician in our sub-region where other treatment modalities such as replantation by microvascular surgery, use of free radial fore-arm flap or sex reassignment to the female gender may not be feasible or acceptable. PMID:12665282

  1. A Tough Grind

    NASA Technical Reports Server (NTRS)

    2004-01-01

    NASA's Mars Exploration Rover Spirit took the four images that make up this mosaic with its microscopic imager on sol 82. The mosaic reveals the drilled surface of the target called 'New York' on the rock dubbed 'Mazatzal.' The rock abrasion tool ground for 3 hours and 45 minutes to create this 3.8 millimeter-deep (0.15 inch) hole. The exposed area is 4.5 centimeters (1.8 inches) in diameter.

    Mazatzal was an interesting rock to grind because it has a lighter tone than the previously ground rocks 'Adirondack' and 'Humphrey,' and because it looks different from its surrounding environment. Scientists hypothesized that Mazatzal's surface might be covered with a rind of weathered material. They drilled through this very top layer to reveal the underlying rock.

    Because Mazatzal's surface was not even, the left half of the rock was penetrated more deeply than the right. As can be seen in this image, the right, darker portion of the rock is still covered by the rind material. Spirit completed a second grind at this location at a different angle to remove the remaining veneer from the right side and create an even deeper hole. Images of this second grind will be sent back to Earth in the next sol or two.

    After the Final Grind The image was acquired on sol 85 after the rover drilled into New York a second time with its rock abrasion tool. Remnants of the dark grey coating that covers Mazatzal's interior can be seen at the right side of the hole. The crack in the rock may have once contained fluids out of which minerals precipitated. Each image making up this mosaic is 3 centimeters (1.2 inches) across.

  2. High-speed, low-damage grinding of advanced ceramics Phase 1. Final report

    SciTech Connect

    Kovach, J.A.; Malkin, S.

    1995-03-01

    In manufacture of structural ceramic components, grinding costs can comprise up to 80% of the entire manufacturing cost. Most of these costs arise from the conventional multi-step grinding process with numerous grinding wheels and additional capital equipment, perishable dressing tools, and labor. In an attempt to reduce structural ceramic grinding costs, a feasibility investigation was undertaken to develop a single step, roughing-finishing process suitable for producing high-quality silicon nitride ceramic parts at high material removal rates at lower cost than traditional, multi-stage grinding. This feasibility study employed combined use of laboratory grinding tests, mathematical grinding models, and characterization of resultant material surface condition. More specifically, this Phase 1 final report provides a technical overview of High-Speed, Low-Damage (HSLD) ceramic grinding and the conditions necessary to achieve the small grain depths of cut necessary for low damage grinding while operating at relatively high material removal rates. Particular issues addressed include determining effects of wheel speed and material removal rate on resulting mode of material removal (ductile or brittle fracture), limiting grinding forces, calculation of approximate grinding zone temperatures developed during HSLD grinding, and developing the experimental systems necessary for determining HSLD grinding energy partition relationships. In addition, practical considerations for production utilization of the HSLD process are also discussed.

  3. 2. DETAIL VIEW OF JOURNAL LATHE, AXLE FINISHING AREA. Grinding ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. DETAIL VIEW OF JOURNAL LATHE, AXLE FINISHING AREA. Grinding bearing diameters on locomotive axle. Norton grinder, 1942 (dated). Melvin Grassmeyer, operator. - Juniata Shops, Machine Shop No. 1, East of Fourth Avenue at Third Street, Altoona, Blair County, PA

  4. 3. DETAIL VIEW OF JOURNAL LATHE, AXLE FINISHING AREA. Grinding ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. DETAIL VIEW OF JOURNAL LATHE, AXLE FINISHING AREA. Grinding bearing diameters on locomotive axle. Norton grinder, 1942 (dated). Melvin Grassmeyer, operator. - Juniata Shops, Machine Shop No. 1, East of Fourth Avenue at Third Street, Altoona, Blair County, PA

  5. Grinding Inside A Toroidal Cavity

    NASA Technical Reports Server (NTRS)

    Mayer, Walter; Adams, James F.; Burley, Richard K.

    1987-01-01

    Weld lines ground smooth within about 0.001 in. Grinding tool for smoothing longitudinal weld lines inside toroidal cavity includes curved tunnel jig to guide grinding "mouse" along weld line. Curvature of tunnel jig matched to shape of toroid so grinding ball in mouse follows circular arc of correct radius as mouse is pushed along tunnel. Tool enables precise control of grindout shape, yet easy to use.

  6. Cylindrical Scanner

    Energy Science and Technology Software Center (ESTSC)

    1999-04-29

    The CS system is designed to provide a very fast imaging system in order to search for weapons on persons in an airport environment. The Cylindrical Scanner moves a vertical transceiver array rapidly around a person standing stationary. The software can be segmented in to three specific tasks. The first task is data acquisition and scanner control. At the operator's request, this task commands the scanner to move and the radar transceiver array to sendmore » data to the computer system in a known and well-ordered manner. The array is moved over the complete aperture in 10 to 12 seconds. At the completion of the array movement the second software task automatically reconstructs the high-resolution image from the radar data utilizing the integrated DSP boards. The third task displays the resulting images, as they become available, to the computer screen for user review and analysis.« less

  7. Cylindrical Scanner

    SciTech Connect

    Hall, Thomas E.

    1999-04-29

    The CS system is designed to provide a very fast imaging system in order to search for weapons on persons in an airport environment. The Cylindrical Scanner moves a vertical transceiver array rapidly around a person standing stationary. The software can be segmented in to three specific tasks. The first task is data acquisition and scanner control. At the operator's request, this task commands the scanner to move and the radar transceiver array to send data to the computer system in a known and well-ordered manner. The array is moved over the complete aperture in 10 to 12 seconds. At the completion of the array movement the second software task automatically reconstructs the high-resolution image from the radar data utilizing the integrated DSP boards. The third task displays the resulting images, as they become available, to the computer screen for user review and analysis.

  8. Cryogenic Grinding: a Physical Technique to Retain Volatile Content in Natural Products

    NASA Astrophysics Data System (ADS)

    Saxena, Rohit; Soni, Aditi; Saxna, S. N.; Rathore, S. S.; Barnwal, P.

    Cryogenics is the study of the production of very low temperature (below -150°C, -238°F or 123K) and the behavior of materials at those temperatures. Similarly, cryogenic grinding is a term supported by the act of grinding a thing at very low temperature. This technique is generally used to grind the material, which contains heat labile constituents viz- volatile oils in seed spices. Due to high fat content in spices, heat is generated, while energy is used to fracture a particle into a smaller size in conventional grinding process. During the normal grinding process, this generated heat causes temperature rise of grinder upto 950C. The increased temperature is responsible for a loss of volatile content in the tune of about 30% and also produces dark colour powder. Generally, continuous operation is not possible in normal grinding process due to melting of fat and sticking of powder on the grinding surface. The loss of volatile content can be significantly reduced by cryogenic grinding technique using liquid nitrogen or liquid carbon dioxide that provides the refrigeration needed to pre-cool the spices and maintain the desired low temperature by absorbing the heat generated during the grinding operation. The extremely low temperature during grinder condenses the volatile matter and retains their presence in spices. The application of cryogenic technology for grinding of spices has been scientifically proved to be a suitable technique with negligible loss of volatile content and improved colour of oil and grinding operation of seeds.

  9. McCarter superfinish grinding for silicon -- an update.

    SciTech Connect

    Anthony, F.; Khounsary, A.; McCarter, D.; Krasnicki, F.; Tangedahl, M.

    2000-11-03

    A grinding technique, referred to as the McCarter Superfinish, for grinding large size optical components is discussed and certain surface characterization information about flatness and the relative magnitude of the subsurface damage in silicon substrates is reported. The flatness measurements were obtained with a Zygo surface analyzer, and the substrate damage measurements were made by x-ray diffraction and acid etching. Results indicate excellent control of flatness and fine surface finish. X-ray measurements show that the diamond wheels with small particle sizes used in the final phases of the grinding operation renders surfaces with relatively small subsurface damage.

  10. Innovative grinding wheel design for cost-effective machining of advanced ceramics. Phase I, final report

    SciTech Connect

    Licht, R.H.; Ramanath, S.; Simpson, M.; Lilley, E.

    1996-02-01

    Norton Company successfully completed the 16-month Phase I technical effort to define requirements, design, develop, and evaluate a next-generation grinding wheel for cost-effective cylindrical grinding of advanced ceramics. This program was a cooperative effort involving three Norton groups representing a superabrasive grinding wheel manufacturer, a diamond film manufacturing division and a ceramic research center. The program was divided into two technical tasks, Task 1, Analysis of Required Grinding Wheel Characteristics, and Task 2, Design and Prototype Development. In Task 1 we performed a parallel path approach with Superabrasive metal-bond development and the higher technical risk, CVD diamond wheel development. For the Superabrasive approach, Task 1 included bond wear and strength tests to engineer bond-wear characteristics. This task culminated in a small-wheel screening test plunge grinding sialon disks. In Task 2, an improved Superabrasive metal-bond specification for low-cost machining of ceramics in external cylindrical grinding mode was identified. The experimental wheel successfully ground three types of advanced ceramics without the need for wheel dressing. The spindle power consumed by this wheel during test grinding of NC-520 sialon is as much as to 30% lower compared to a standard resin bonded wheel with 100 diamond concentration. The wheel wear with this improved metal bond was an order of magnitude lower than the resin-bonded wheel, which would significantly reduce ceramic grinding costs through fewer wheel changes for retruing and replacements. Evaluation of ceramic specimens from both Tasks 1 and 2 tests for all three ceramic materials did not show evidence of unusual grinding damage. The novel CVD-diamond-wheel approach was incorporated in this program as part of Task 1. The important factors affecting the grinding performance of diamond wheels made by CVD coating preforms were determined.

  11. CNC grinding of valve housing piston holes

    SciTech Connect

    Ashbaugh, F.A.

    1991-11-01

    Grinding has traditionally been used for machining operations requiring close dimensional tolerances and better surface finishes than can be obtained from other metal removal techniques. Using a grinding process for the last metal removal operation, the close tolerances and surface finishes can be easily held while eliminating the adverse conditions from the current metal removal processes. Pre-machined test parts were sent to a machine tool supplier to have the critical inside features of a typical piston bore finish machined using an internal CNC grinder equipped with high-frequency spindles. The piston bore and sealing angle were ground using a standard 120-grit silicon carbide wheel. The wafer step was machined using a solid carbide tool designed and built at Allied-Signal Inc., Kansas City Division (KCD). Six consecutive parts were machined for evaluation. The repeatability on all six parts was within print requirements. The inside corner radii was less than 0.002 in. and the surface finish was 8.2 arithmetical average or better as defined by ANSI B46.1, Surface Texture. Machining parts by this grinding process would eliminate bellmouth, chatter, waviness, and traveler polishing operations. It would produce a superior surface finish, small inside radii, and small easily removable burrs. It would also hold tolerances closer and significantly reduce scrap, rework, rejects, and deviations. 1 fig.

  12. Grinding process monitoring based on electromechanical impedance measurements

    NASA Astrophysics Data System (ADS)

    Marchi, Marcelo; Guimarães Baptista, Fabricio; de Aguiar, Paulo Roberto; Bianchi, Eduardo Carlos

    2015-04-01

    Grinding is considered one of the last processes in precision parts manufacturing, which makes it indispensable to have a reliable monitoring system to evaluate workpiece surface integrity. This paper proposes the use of the electromechanical impedance (EMI) method to monitor the surface grinding operation in real time, particularly the surface integrity of the ground workpiece. The EMI method stands out for its simplicity and for using low-cost components such as PZT (lead zirconate titanate) piezoelectric transducers. In order to assess the feasibility of applying the EMI method to the grinding process, experimental tests were performed on a surface grinder using a CBN grinding wheel and a SAE 1020 steel workpiece, with PZT transducers mounted on the workpiece and its holder. During the grinding process, the electrical impedance of the transducers was measured and damage indices conventionally used in the EMI method were calculated and compared with workpiece wear, indicating the surface condition of the workpiece. The experimental results indicate that the EMI method can be an efficient and cost-effective alternative for monitoring precision workpieces during the surface grinding process.

  13. Cylindrical wormholes

    SciTech Connect

    Bronnikov, K. A.; Lemos, Jose P. S.

    2009-05-15

    It is shown that the existence of static, cylindrically symmetric wormholes does not require violation of the weak or null energy conditions near the throat, and cylindrically symmetric wormhole geometries can appear with less exotic sources than wormholes whose throats have a spherical topology. Examples of exact wormhole solutions are given with scalar, spinor and electromagnetic fields as sources, and these fields are not necessarily phantom. In particular, there are wormhole solutions for a massless, minimally coupled scalar field in the presence of a negative cosmological constant, and for an azimuthal Maxwell electromagnetic field. All these solutions are not asymptotically flat. A no-go theorem is proved, according to which a flat (or string) asymptotic behavior on both sides of a cylindrical wormhole throat is impossible if the energy density of matter is everywhere nonnegative.

  14. Machining Thin-Walled Cylindrical Parts

    NASA Technical Reports Server (NTRS)

    Cimbak, Joe; Spagnolo, Jim; Kraus, Dan

    1988-01-01

    Cylindrical walls only few thousandths of inch thick machined accurately and without tears or punctures with aid of beryllium copper mandrel. Chilled so it contracts, then inserted in cylinder. As comes to room temperature, mandrel expands and fits snugly inside cylinder. Will not allow part to slide and provides solid backup to prevent deflection when part machined by grinding wheel. When machining finished, cylinder-and-mandrel assembly inserted in dry ice, mandrel contracts and removed from part.

  15. Ceramic-bonded abrasive grinding tools

    DOEpatents

    Holcombe, Jr., Cressie E.; Gorin, Andrew H.; Seals, Roland D.

    1994-01-01

    Abrasive grains such as boron carbide, silicon carbide, alumina, diamond, cubic boron nitride, and mullite are combined with a cement primarily comprised of zinc oxide and a reactive liquid setting agent and solidified into abrasive grinding tools. Such grinding tools are particularly suitable for grinding and polishing stone, such as marble and granite.

  16. Ceramic-bonded abrasive grinding tools

    DOEpatents

    Holcombe, C.E. Jr.; Gorin, A.H.; Seals, R.D.

    1994-11-22

    Abrasive grains such as boron carbide, silicon carbide, alumina, diamond, cubic boron nitride, and mullite are combined with a cement primarily comprised of zinc oxide and a reactive liquid setting agent and solidified into abrasive grinding tools. Such grinding tools are particularly suitable for grinding and polishing stone, such as marble and granite.

  17. Influence parameters of impact grinding mills

    NASA Technical Reports Server (NTRS)

    Hoeffl, K.; Husemann, K.; Goldacker, H.

    1984-01-01

    Significant parameters for impact grinding mills were investigated. Final particle size was used to evaluate grinding results. Adjustment of the parameters toward increased charge load results in improved efficiency; however, it was not possible to define a single, unified set to optimum grinding conditions.

  18. "Grinding" cavities in polyurethane foam

    NASA Technical Reports Server (NTRS)

    Brower, J. R.; Davey, R. E.; Dixon, W. F.; Robb, P. H.; Zebus, P. P.

    1980-01-01

    Grinding tool installed on conventional milling machine cuts precise cavities in foam blocks. Method is well suited for prototype or midsize production runs and can be adapted to computer control for mass production. Method saves time and materials compared to bonding or hot wire techniques.

  19. Ultrasonic precision optical grinding technology

    NASA Astrophysics Data System (ADS)

    Cahill, Michael J.; Bechtold, Michael J.; Fess, Edward; Wolfs, Frank L.; Bechtold, Rob

    2015-10-01

    As optical geometries become more precise and complex and a wider range of materials are used, the processes used for manufacturing become more critical. As the preparatory stage for polishing, this is especially true for grinding. Slow processing speeds, accelerated tool wear, and poor surface quality are often detriments in manufacturing glass and hard ceramics. The quality of the ground surface greatly influences the polishing process and the resulting finished product. Through extensive research and development, OptiPro Systems has introduced an ultrasonic assisted grinding technology, OptiSonic, which has numerous advantages over traditional grinding processes. OptiSonic utilizes a custom tool holder designed to produce oscillations in line with the rotating spindle. A newly developed software package called IntelliSonic is integral to this platform. IntelliSonic automatically characterizes the tool and continuously optimizes the output frequency for optimal cutting while in contact with the part. This helps maintain a highly consistent process under changing load conditions for a more accurate surface. Utilizing a wide variety of instruments, test have proven to show a reduction in tool wear and increase in surface quality while allowing processing speeds to be increased. OptiSonic has proven to be an enabling technology to overcome the difficulties seen in grinding of glass and hard optical ceramics. OptiSonic has demonstrated numerous advantages over the standard CNC grinding process. Advantages are evident in reduced tool wear, better surface quality, and reduced cycle times due to increased feed rates. These benefits can be seen over numerous applications within the precision optics industry.

  20. Critical parameters for grinding large sapphire window panels

    NASA Astrophysics Data System (ADS)

    Bashe, Joseph R.; Dempsey, Gene; Akwani, Ikerionwu A.; Jacoby, Keith T.; Hibbard, Douglas L.

    2007-04-01

    Advances in optical manufacturing and testing technologies for sapphire material are required to support the increasing use of large-aperture sapphire panels as windscreens for various electro-optical system applications. Single surface grinding is a crucial process step in both the figuring and finishing of optical components. Improper grinding can make subsequent polishing operations more difficult and time consuming. Poor grinding can also lead to the introduction of surface stress and sub-surface damage which can affect critical opto-mechanical performance characteristics such as strength and durability. Initial efforts have been completed at Exotic Electro-Optics under the funding of the Office of Naval Research and the Air Force Research Laboratory to investigate a number of process enhancements in the grinding of a-plane sapphire panels. The information gained from this study will ultimately provide a better understanding of the overall manufacturing process leading to optimized process time and cost. EEO has completed two sets of twelve-run Plackett-Burman designs of experiment (DOE) to study the effects of fundamental grinding parameters on sapphire panel surfaces. The relative importance of specific process parameters on window characteristics including surface roughness, stress, sub-surface damage are reported.

  1. Achieving process control through improved grinding techniques for ferrite materials

    SciTech Connect

    Bruce, J.

    1995-09-01

    In manufacturing soft ferrite materials the particle size of the raw material has a significant impact on the reactivity of calcination. The control of particle size distribution and final formulation at wet milling after calcining impacts the reactivity during sintering and the magnetic properties of the final product. This paper will deal with steps taken to improve process control during the grinding operations of raw material and calcine in soft ferrite production. Equipment modifications as well as changes to the grinding and material handling techniques will be included. All examples of process control and improvements will be supported by data.

  2. Fused silica fine grinding with low roughness

    NASA Astrophysics Data System (ADS)

    Dai, Lei; Gu, Yongqiang; Wu, Di

    2014-08-01

    Lithography-optics is one of the most complex optical systems. The fine grinding process is the most important step before polishing. Roughness and sub-surface damage (SSD) are essential outputs of fine grinding. We demonstrate the method that use fix abrasive cup tool with CNC grinding machine to complete the fine grinding process, even instead of lapping process. And experiment sample roughness can reach 23.40nm rms and Ra 18.554nm. The SSD estimate is about 2 μm which is also smaller than commercial lapping process. The fine grinding output can satisfy the lithography optic fabrication demands and efficiently reduce the polishing time.

  3. Characterization of grinding wheels: An annotated Bibliography. Final report

    SciTech Connect

    McClung, R.W.

    1995-12-01

    The characteristics of grinding wheels, after both fabrication and periods of operation, have a significant effect on the processed surface and the mechanical properties of advanced ceramics. An extensive literature survey and review has been conducted to determine and catalogue the various characterization methods that have been investigated and reported. Although many of the references have addressed the grinding of metals, the historical and technical merit justify their inclusion in this bibliography. For convenience, the references have been subdivided into nine subheadings: Nondestructive examination; elasticity and stiffness; wheel hardness; topography and profilometry; observation of texture of wheel surfaces wheel wear; in process monitoring of grinding, acoustic emission, other; characteristics of ground surfaces; and miscellaneous.

  4. Microfabricated cylindrical ion trap

    DOEpatents

    Blain, Matthew G.

    2005-03-22

    A microscale cylindrical ion trap, having an inner radius of order one micron, can be fabricated using surface micromachining techniques and materials known to the integrated circuits manufacturing and microelectromechanical systems industries. Micromachining methods enable batch fabrication, reduced manufacturing costs, dimensional and positional precision, and monolithic integration of massive arrays of ion traps with microscale ion generation and detection devices. Massive arraying enables the microscale cylindrical ion trap to retain the resolution, sensitivity, and mass range advantages necessary for high chemical selectivity. The microscale CIT has a reduced ion mean free path, allowing operation at higher pressures with less expensive and less bulky vacuum pumping system, and with lower battery power than conventional- and miniature-sized ion traps. The reduced electrode voltage enables integration of the microscale cylindrical ion trap with on-chip integrated circuit-based rf operation and detection electronics (i.e., cell phone electronics). Therefore, the full performance advantages of microscale cylindrical ion traps can be realized in truly field portable, handheld microanalysis systems.

  5. Thermally induced grinding damage in cast equiaxed nickel-based superalloys

    SciTech Connect

    Kovach, J.A.

    1986-01-01

    The overall objective of this program was to increase the understanding and productivity of conventional grinding operations utilized in the finishing of cast equiaxed nickel-based superalloy components. To achieve this overall goal a four phase approach was employed. Initially, a grinding energy partition relationship for conventional grinding of superalloys was developed. Secondly, the mechanisms and conditions that influence superalloy microcracking during abusive grinding were determined. Third, building on the above relationships, a means of readily predicting the onset of grinding damage in cast Rene-77 and B-1900 superalloys was established. Finally, the results were implemented in production surface grinding operations to increase superalloy grinding quality and productivity. Finite element analyses were utilized to determine the superalloy grinding zone temperatures and residual stresses. The results indicated that Rene-77 microcracks are not formed by the residual stresses alone. The effects of constitutional liquation or weakening of the grain boundaries due to rapid heating to such temperatures were shown to be significant. It was then demonstrated that workplace damage would occur when the combined conducted and convected heat flux exceeded a critical limit.

  6. Optimization of Cylindrical Hall Thrusters

    SciTech Connect

    Yevgeny Raitses, Artem Smirnov, Erik Granstedt, and Nathaniel J. Fi

    2007-07-24

    The cylindrical Hall thruster features high ionization efficiency, quiet operation, and ion acceleration in a large volume-to-surface ratio channel with performance comparable with the state-of-the-art annular Hall thrusters. These characteristics were demonstrated in low and medium power ranges. Optimization of miniaturized cylindrical thrusters led to performance improvements in the 50-200W input power range, including plume narrowing, increased thruster efficiency, reliable discharge initiation, and stable operation. __________________________________________________

  7. Optimization of Cylindrical Hall Thrusters

    SciTech Connect

    Yevgeny Raitses, Artem Smirnov, Erik Granstedt, and Nathaniel J. Fisch

    2007-11-27

    The cylindrical Hall thruster features high ionization efficiency, quiet operation, and ion acceleration in a large volume-to-surface ratio channel with performance comparable with the state-of-the-art annular Hall thrusters. These characteristics were demonstrated in low and medium power ranges. Optimization of miniaturized cylindrical thrusters led to performance improvements in the 50-200W input power range, including plume narrowing, increased thruster efficiency, reliable discharge initiation, and stable operation.

  8. Comparison of High-Speed Operating Characteristics of Size 215 Cylindrical-Roller Bearings as Determined in Turbojet Engine and in Laboratory Test Rig

    NASA Technical Reports Server (NTRS)

    Macks, E Fred; Nemeth, Zolton N

    1952-01-01

    A comparison of the operating characteristics of 75-millimeter-bore (size 215) cylindrical-roller one-piece inner-race-riding cage-type bearings was made by means of a laboratory test rig and a turbojet engine. Cooling correlation parameters were determined by means of dimensional analysis, and the generalized results for both the inner- and the outer-race bearing operating temperatures are computed for the laboratory test rig and the turbojet engine. A method is given that enables the designer to predict the inner- and outer-race turbine roller-bearing temperatures from single curves, regardless of variations in speed, load, oil flow, oil inlet temperature, oil inlet viscosity, oil-jet diameter, or any combination of these parameters.

  9. Correlation between mass transfer coefficient kLa and relevant operating parameters in cylindrical disposable shaken bioreactors on a bench-to-pilot scale

    PubMed Central

    2013-01-01

    Background Among disposable bioreactor systems, cylindrical orbitally shaken bioreactors show important advantages. They provide a well-defined hydrodynamic flow combined with excellent mixing and oxygen transfer for mammalian and plant cell cultivations. Since there is no known universal correlation between the volumetric mass transfer coefficient for oxygen kLa and relevant operating parameters in such bioreactor systems, the aim of this current study is to experimentally determine a universal kLa correlation. Results A Respiration Activity Monitoring System (RAMOS) was used to measure kLa values in cylindrical disposable shaken bioreactors and Buckingham’s π-Theorem was applied to define a dimensionless equation for kLa. In this way, a scale- and volume-independent kLa correlation was developed and validated in bioreactors with volumes from 2 L to 200 L. The final correlation was used to calculate cultivation parameters at different scales to allow a sufficient oxygen supply of tobacco BY-2 cell suspension cultures. Conclusion The resulting equation can be universally applied to calculate the mass transfer coefficient for any of seven relevant cultivation parameters such as the reactor diameter, the shaking frequency, the filling volume, the viscosity, the oxygen diffusion coefficient, the gravitational acceleration or the shaking diameter within an accuracy range of +/− 30%. To our knowledge, this is the first kLa correlation that has been defined and validated for the cited bioreactor system on a bench-to-pilot scale. PMID:24289110

  10. Ultraprecision, high stiffness CNC grinding machines for ductile mode grinding of brittle materials

    NASA Astrophysics Data System (ADS)

    McKeown, Patrick A.; Carlisle, Keith; Shore, Paul; Read, R. F.

    1990-10-01

    Under certain controlled conditions it is now possible to machine brittle materials such as glasses and ceramics using single or multi-point diamond tools (grinding), so that material is removed by plastic flow, leaving crack-free surfaces. This process is called 'shear' or 'ductile' mode grinding. It represents a major breakthrough in modern manufacturing engineering since it promises to enable: - complex optical components, both transmission and reflecting to be generated by advanced CNC machines with very little (or even zero) subsequent polishing. - complex shaped components such as turbine blades, nozzle guide vanes, etc. to be finish machined after near net shape forming, to high precision in advanced ceramics such as silicon nitride, without inducing micro-cracking and thus lowering ultimate rupture strength and fatigue life. Ductile mode "damage free" grinding occurs when the volume of materials stressed by each grit of the grinding wheel is small enough to yield rather than exhibit brittle fracture, i.e. cracking. In practice, this means maintaining the undeformed chip thickness to below the ductile-brittle transition value; this varies from material to material but is generally in the order of 0.1 pm or 100 nm, (hence the term "nanogrinding" is sometimes used) . Thus the critical factors for operating successfully in the ductile regime are machine system accuracy and dynamic stiffness between each grit and the workpiece. In detail this means: (i) High precision 'truing' of the diamond grits, together with dressing of the wheel bond to ensure adequate ' openness'; (ii) Design and build of the grinding wheel spindle with very high dynamic stiffness; error motions, radial and axial, must be considerably less than 100 nfl. (iii) Design and build of the workpiece carriage motion system with very high dynamic stiffness; error motions, linear or rotary, must be well within 100 nm. (iv) Smooth, rumble-free, high-stiffness servo-drives controlling the motions

  11. Grinding arrangement for ball nose milling cutters

    NASA Technical Reports Server (NTRS)

    Burch, C. F. (Inventor)

    1974-01-01

    A grinding arrangement for spiral fluted ball nose end mills and like tools includes a tool holder for positioning the tool relative to a grinding wheel. The tool is mounted in a spindle within the tool holder for rotation about its centerline and the tool holder is pivotably mounted for angular movement about an axis which intersects that centerline. A follower arm of a cam follower secured to the spindle cooperates with a specially shaped cam to provide rotation of the tool during the angular movement of the tool holder during the grinding cycle, by an amount determined by the cam profile. In this way the surface of the cutting edge in contact with the grinding wheel is maintained at the same height on the grinding wheel throughout the angular movement of the tool holder during the grinding cycle.

  12. Changeing of fly ash leachability after grinding

    NASA Astrophysics Data System (ADS)

    Lakatos, J.; Szabo, R.; Racz, A.; Banhidi, O.; Mucsi, G.

    2016-04-01

    Effect of grinding on the reactivity of fly ash used for geopolymer production was tested. Extraction technique using different alkaline and acidic solutions were used for detect the change of the solubility of elements due to the physical and mechano-chemical transformation of minerals in function of grinding time. Both the extraction with alkaline and acidic solution have detected improvement in solubility in function of grinding time. The enhancement in alkaline solution was approx. 100% in case of Si and Al. The acidic medium able to dissolve the fly ash higher manner than the alkaline, therefore the effect of grinding was found less pronounced.

  13. Autogenous grinding for bath scraps recycling

    SciTech Connect

    Pinoncely, A.; Podda, P.

    1996-10-01

    In the early 80`s, FCB designed an original process for the recycling of bath scraps in Aluminum smelters, using a single stage fully air-swept autogenous mill. Since then, the 9 industrial references confirmed and even exceeded the expectation in terms of dust-free and easy to run operation, high recovery ratio of bath among the metallic scraps, and low maintenance cost. Problems encountered on conventional processes belong to the old days, and new projects tend to give an increasing importance to classification and storage of crushed products, autogenous grinding being already recognized as the most suitable, simple and reliable process route. The present paper describes this original process and draws up the overall performances of ten years of experience.

  14. Study on numerical simulation of the dynamic impact effect for optical glass grinding with single grit

    NASA Astrophysics Data System (ADS)

    Chen, Jiang; Zhang, Feihu; Hang, Zhao; Yong, Zhang; Su, Jianbo

    It studies failure mechanism of optical glass with impact stress from grit, according to the dynamic impact effect in the process of optical glass grinding with single grit. With the distribution regularity of crack which from the grit dynamic impact, it established mathematical model of cylindrical stress wave which coaxial with wavefront. Analyzing and establishing the control equations for cylindrical stress wave, using finite-difference technique to simulate the dynamic impact effect for optical glass grinding with single grit and adopting Zwas numerical methods with source term hyperbolic curve partial differential equations to analysis and study the dissemination rule, diffusion rule and change rule, the simulation analysis shows that in the dissemination process of grit impact wave , wavefront occurred diffusion and there are tensile stress generated as well as oscillation.

  15. APPARATUS FOR GRINDING SPHERICAL BODIES

    DOEpatents

    Burch, R.F. Jr.

    1963-09-24

    A relatively inexpensive device is described for grinding rough ceramic bodies into accurate spherical shapes using a conventional drill press and a belt sander. A horizontal disk with an abrasive-surfaced recess in its lower face is mounted eccentrically on a vertical shaft which is forced downward against a stop by a spring. Bodies to be ground are placed in the recess and are subjected to the abrasive action of the belt sander as the disk is rotated by the drill press. (AEC)

  16. 'Diamond Jenness': Before the Grind

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This microscopic imager mosaic of the rock called 'Diamond Jenness' was snapped on sol 177 before NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool, or 'Rat.'

    Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer. On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

    The image mosaic is about 6 centimeters (2.4 inches) across.

  17. 'Diamond Jenness': After the Grind

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This microscopic imager mosaic taken by NASA's Mars Exploration Rover Opportunity shows the rock dubbed 'Diamond Jenness.' It was taken on sol 177 (July 23, 2004) after the rover first ground into the rock with its rock abrasion tool, or 'Rat.' The rover later ground into the rock a second time. A sliced spherule, or 'blueberry,' is visible in the upper left corner of the hole.

    Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

    On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

    The image mosaic is about 6 centimeters (2.4 inches) across.

  18. 'Diamond Jenness': A Tough Grind

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This microscopic imager mosaic of the target area called 'Diamond Jenness' was taken after NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool for a second time.

    Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

    On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

    The image mosaic is about 6 centimeters (2.4 inches) across.

  19. Lathe converted for grinding aspheric surfaces

    NASA Technical Reports Server (NTRS)

    Larmer, J. W.; Levinsohn, M.; Mc Craw, D.; Pessagno, E. H.; Taub, F. J.

    1964-01-01

    A standard overarm tracing lathe converted by the addition of an independently driven diamond grinding wheel is used for grinding aspheric surfaces. The motion of the wheel is controlled by the lathe air tracer following the template which produces the desired aspheric profile.

  20. Precision grinding process development for brittle materials

    SciTech Connect

    Blaedel, K L; Davis, P J; Piscotty, M A

    1999-04-01

    High performance, brittle materials are the materials of choice for many of today's engineering applications. This paper describes three separate precision grinding processes developed at Lawrence Liver-more National Laboratory to machine precision ceramic components. Included in the discussion of the precision processes is a variety of grinding wheel dressing, truing and profiling techniques.

  1. Precision diamond grinding of ceramics and glass

    SciTech Connect

    Smith, S.; Paul, H.; Scattergood, R.O.

    1988-12-01

    A new research initiative will be undertaken to investigate the effect of machine parameters and material properties on precision diamond grinding of ceramics and glass. The critical grinding depth to initiate the plastic flow-to-brittle fracture regime will be directly measured using plunge-grind tests. This information will be correlated with machine parameters such as wheel bonding and diamond grain size. Multiaxis grinding tests will then be made to provide data more closely coupled with production technology. One important aspect of the material property studies involves measuring fracture toughness at the very short crack sizes commensurate with grinding damage. Short crack toughness value`s can be much less than the long-crack toughness values measured in conventional fracture tests.

  2. Evaluation of Recycle Grinding Performance in Flour Milling

    NASA Astrophysics Data System (ADS)

    Mazlina Mustapa Kamal, Siti; Webb, Colin

    A typical flour milling process is a very linear operation that is almost entirely void of recycled streams where separate fractions from each operation go ahead as new streams to the next operation. In some cases, there are opportunities for combining some streams, for recycling particles that have been insufficiently broken to go back to the same roller mill. This study introduces this recycle concept in flour milling process at second break system. The recycle grinding assessment was made using a Satake STR-100 test roller mill. The recycle process was started after the second break system and the number of recycle grinding was up to 7 regrinds. The particle size distribution and ash analysis were produced to describe the behaviour of the recycle grinding performance. The material release was sifted on a range of sieves and the ash content was analysed using a laboratory furnace. The performance for each recycle stage was investigated. It was determined that it is possible for some coarse particles that contain only bran to keep being recycled in the recycle circuit. A purging operation was recommended to be included in the recycle system, to separate the unwanted particles.

  3. Machining and grinding: High rate deformation in practice

    SciTech Connect

    Follansbee, P.S.

    1993-04-01

    Machining and grinding are well-established material-working operations involving highly non-uniform deformation and failure processes. A typical machining operation is characterized by uncertain boundary conditions (e.g.,surface interactions), three-dimensional stress states, large strains, high strain rates, non-uniform temperatures, highly localized deformations, and failure by both nominally ductile and brittle mechanisms. While machining and grinding are thought to be dominated by empiricism, even a cursory inspection leads one to the conclusion that this results more from necessity arising out of the complicated and highly interdisciplinary nature of the processes than from the lack thereof. With these conditions in mind, the purpose of this paper is to outline the current understanding of strain rate effects in metals.

  4. Machining and grinding: High rate deformation in practice

    SciTech Connect

    Follansbee, P.S.

    1993-01-01

    Machining and grinding are well-established material-working operations involving highly non-uniform deformation and failure processes. A typical machining operation is characterized by uncertain boundary conditions (e.g.,surface interactions), three-dimensional stress states, large strains, high strain rates, non-uniform temperatures, highly localized deformations, and failure by both nominally ductile and brittle mechanisms. While machining and grinding are thought to be dominated by empiricism, even a cursory inspection leads one to the conclusion that this results more from necessity arising out of the complicated and highly interdisciplinary nature of the processes than from the lack thereof. With these conditions in mind, the purpose of this paper is to outline the current understanding of strain rate effects in metals.

  5. Measurement and analysis of forces in grinding of silicon nitride

    SciTech Connect

    Jahanmir, S.; Hwang, T.; Whitenton, E.P.; Job, L.S.; Evans, C.J.

    1995-12-31

    Using an instrumented surface grinder, the two components of grinding forces (normal and tangential) were measured for different types of silicon nitride ceramics. The influences of grinding parameters, such as down feed and table speed, and grinding fluids on forces were determined. In addition to these measurements, the specific grinding energy defined as the energy per unit volume of removed material was calculated. This parameter and the measured forces were then analyzed to determine possible correlations with mechanical properties of the silicon nitrides. It was found that, in general, the grinding forces and the specific grinding energy increase with the hardness. Both the grinding forces and the specific grinding energy were influenced by the grinding fluid and the grinding parameters. The implication of these results on the mechanisms of material removal in grinding of silicon nitride and the possible tribological effects are discussed.

  6. Surface topography of cylindrical gear wheels after smoothing in abrasive mass, honing and shot peening

    NASA Astrophysics Data System (ADS)

    Michalski, J.; Pawlus, P.; Żelasko, W.

    2011-08-01

    The present paper presents the analysis of surface topography of gear teeth as the result of final machining processes. Teeth of multiple cylindrical gears shaped by grinding were smoothed in abrasive mass, honed or shot peened. The measurement of gears were made using coordinate measuring machine and 3D surface topography stylus instrument. The following deviations were studied; pitch deviation, total pitches deviations, variation of teeth thickness and deviation of gear radial run-out. Changes in teeth surface topography during machining process were determined. 3D surface topography parameters, surface directionality as well as areal autocorrelation and power spectral density functions were taken into consideration. As the results of the analysis, the best surface topography with regard to gear operational properties was recommended.

  7. Chatter in a transverse grinding process

    NASA Astrophysics Data System (ADS)

    Yan, Yao; Xu, Jian; Wiercigroch, Marian

    2014-02-01

    In transverse grinding, the wheel moves along the workpiece, which induces unique grinding dynamics. To understand these dynamic phenomena, specifically the grinding chatter, a new dynamical model of the process is proposed, in which the wheel position is assumed to be quasi-static since the transverse wheel velocity is small. From the stability and bifurcation analyses of the chatter vibration, it appears that the dynamics of the process is governed by the quasi-static interactions. Moreover, the obtained results also show that the wheel and workpiece chatters are quite different, having continuous and intermittent characters respectively.

  8. Mass exchange during simultaneous grinding and dissolution

    SciTech Connect

    Aksel'rud, G.A.; Semenishin, E.M.; Kopyt, S.Ya.; Trotskii, V.I.

    1988-03-20

    Extraction of ore components of interest has a number of disadvantages, one of which being low efficiency. Combining the grinding and dissolution steps in one apparatus makes the process more efficient. Adoption of this technology, however, requires theoretical and mathematical studies. This paper reports the kinetics of simultaneous grinding and dissolution of copper-containing minerals. Simultaneous grinding and dissolution accelerated several fold the mass transfer of components of interest in the interaction of malachite and azurite with sulfuric acid solutions. The complete dissolution time was determined by adding the experimental rates of dissolution and abrasion.

  9. Shear-mode grinding force criteria of Zerodur and Pyrex

    NASA Astrophysics Data System (ADS)

    Hashimoto, Hiroshi; Imai, Kenichiro

    1995-08-01

    Experimental grinding of Zerodur and Pyrex demonstrated shear-mode grinding criteria (SM' GFC), which is a repeatable deterministic function of grinding conditions including materials and grinding wheels. Both criteria as with BK7 glass previously reported, are found to be the logarithmic function of removal rate.

  10. Automatic grinding apparatus to control uniform specimen thicknesses

    DOEpatents

    Bryner, J.S.

    1981-01-07

    This invention is directed to a new and improved grinding apparatus comprisng: (1) a movable grinding surface; (2) a specimen holder; (3) a dislacing means for moving the holder and/or grinding surface toward one another; and (4) at least three means for limiting displacement of the holder to the grinding surface.

  11. Automatic grinding apparatus to control uniform specimen thicknesses

    SciTech Connect

    Bryner, Joseph S.

    1982-01-01

    This invention is directed to a new and improved grinding apparatus comprising (1) a movable grinding surface, (2) a specimen holder, (3) a displacing device for moving the holder and/or grinding surface toward one another, and (4) at least three devices for limiting displacement of the holder to the grinding surface.

  12. High speed low damage grinding of advanced ceramics - Phase II Final Report

    SciTech Connect

    Kovach, J.A.; Malkin, S.

    2000-02-01

    In the manufacture of structural ceramic components, grinding costs can comprise up to 80% of the entire manufacturing cost. As a result, one of the most challenging tasks faced by manufacturing process engineers is the development of a ceramic finishing process to maximize part throughput while minimizing costs and associated scrap levels. The efforts summarized in this report represent the second phase of a program whose overall objective was to develop a single-step, roughing-finishing process suitable for producing high-quality silicon nitride parts at high material removal rates and at substantially lower cost than traditional, multi-stage grinding processes. More specifically, this report provides a technical overview of High-Speed, Low-Damage (HSLD) ceramic grinding which employs elevated wheel speeds to achieve the small grain depths of cut necessary for low-damage grinding while operating at relatively high material removal rates. The study employed the combined use of laboratory grinding tests, mathematical grinding models, and characterization of the resultant surface condition. A single-step, roughing-finishing process operating at high removal rates was developed and demonstrated.

  13. High Pressure Mass Spectrometry: The Generation of Mass Spectra at Operating Pressures Exceeding 1 Torr in a Microscale Cylindrical Ion Trap.

    PubMed

    Blakeman, Kenion H; Wolfe, Derek W; Cavanaugh, Craig A; Ramsey, J Michael

    2016-05-17

    We present the first demonstration of high pressure mass spectrometry (HPMS), which we define as mass spectrometry performed at pressures greater than 100 mTorr. Mass analysis is shown at operational pressures exceeding 1 Torr of helium buffer gas. A differentially pumped MS system was constructed for HPMS development consisting of two chambers. The first chamber (mass analysis chamber) was operated at pressures up to 1.2 Torr and contained the ionization source and a microscale cylindrical ion trap (CIT) mass analyzer. The CIT had critical dimensions of r0 = 500 μm and z0 = 650 μm. The second chamber was held at a lower pressure (≤10 mTorr) and contained an electron multiplier for detection. Mass spectra for xenon, 2-chloroethyl ethyl sulfide (CEES), and octane were acquired with helium buffer gas pressures ranging from 0.04 to 1.2 Torr in the mass analysis chamber. Full-width at half-maximum of mass spectral peaks was found to increase 143% for xenon, 40% for CEES, and 77% for octane over this pressure range, with maximum peak widths of 1.19, 1.26, and 0.82 Da, respectively. Data were fitted with an algebraic model that factors in ion-neutral collision peak broadening effects at high pressures. Experimental and theoretical peak broadening slopes showed good agreement at buffer gas pressures greater than 0.2 Torr. Experiments presented here demonstrate mass spectrometry at pressures orders of magnitude higher than conventionally practiced with any type of mass analyzer. The use of HPMS provides a way to eliminate turbo pumping requirements, leading to significant reduction in MS system size, weight, and power and facilitating a path toward compact/hand-held mass spectrometers with numerous potential applications. PMID:27109864

  14. Micromachining using ultrasonic impact grinding

    NASA Astrophysics Data System (ADS)

    Medis, Praveen S.; Thurman Henderson, H.

    2005-08-01

    Although largely unknown in the MEMS community, micromachining using ultrasonic impact grinding (UIG) is a fascinating yet easy fabrication scheme to achieve virtually any shape, such as a shallow or deep reservoir, a channel, a via, etc, in silicon, glass and other commonly used ceramic and semiconductor materials in the MEMS field. Because of the patterning and masking issues, etching even shallow channels or vias in a pre-processed silicon/glass/ceramic substrate is somewhat difficult, if not impossible. However, by using UIG one can achieve such structures, up to millimeters in depth in virtually no time. Furthermore, in silicon substrates, the orientation or any other physical dimension of the feature will no longer be constrained as in anisotropic etching by the crystallographic planes and directions; and in amorphous glass or ceramic substrates, features with vertical walls can be achieved, otherwise usually accomplished only by expensive laser ablation. Thus, the authors believe that this UIG process could open up many avenues to easily and quickly achieve the larger MEMS structures as well as packaging for both prototype and for production in silicon, glass and ceramic.

  15. Cylindrical geometry hall thruster

    DOEpatents

    Raitses, Yevgeny; Fisch, Nathaniel J.

    2002-01-01

    An apparatus and method for thrusting plasma, utilizing a Hall thruster with a cylindrical geometry, wherein ions are accelerated in substantially the axial direction. The apparatus is suitable for operation at low power. It employs small size thruster components, including a ceramic channel, with the center pole piece of the conventional annular design thruster eliminated or greatly reduced. Efficient operation is accomplished through magnetic fields with a substantial radial component. The propellant gas is ionized at an optimal location in the thruster. A further improvement is accomplished by segmented electrodes, which produce localized voltage drops within the thruster at optimally prescribed locations. The apparatus differs from a conventional Hall thruster, which has an annular geometry, not well suited to scaling to small size, because the small size for an annular design has a great deal of surface area relative to the volume.

  16. Effect of grinding conditions on the fatigue life of titanium 5Al-2.5Sn alloy

    NASA Technical Reports Server (NTRS)

    Rangaswamy, P.; Terutung, H.; Jeelani, S.

    1991-01-01

    An investigation into the effect of grinding conditions on the fatigue life of titanium 5Al-2.5Sn is presented. Damage to surface integrity and changes in the residual stresses distribution are studied to assess changes in fatigue life. A surface grinding machine, operating at speeds ranging from 2000 to 6000 fpm and using SiC wheels of grit sizes 60 and 120, was used to grind flat subsize specimens of 0.1-in. thickness. After grinding, the specimens were fatigued at a chosen stress and compared with the unadulterated material. A standard profilometer, a microhardness tester, and a scanning electron microscope were utilized to examine surface characteristics and measure roughness and hardness. Increased grinding speed in both wet and dry applications tended to decrease the fatigue life of the specimens. Fatigue life increased markedly at 2000 fpm under wet conditions, but then decreased at higher speeds. Grit size had no effect on the fatigue life.

  17. Production of Near-Mirror Surface Quality by Precision Grinding

    NASA Technical Reports Server (NTRS)

    Dimofte, Florin; Krantz, Timothy

    2003-01-01

    Mechanical components such as gears and bearings operate with the working surfaces in intimate contact with a mating part. The performance of such components will be influenced by the quality of the working surface. In general, a smoother surface will perform better than a rougher surface since the lubrication conditions are improved. For example, surfaces with a special near-mirror quality finish of low roughness performed better than ground surfaces when tested using a block-on-ring arrangement. Bearings with near-mirror quality have been tested and analyzed; lower running torques were measured and improved fatigue life was anticipated. Experiments have been done to evaluate the performance of gears with improved, low roughness surface finishing. The measured performance improvements include an increased scuffing (scoring) load capacity by a factor of 1.6, a 30-percent reduction of gear tooth running friction, and longer fatigue lives by a factor of about four. One can also anticipate that near-mirror quality surface finishing could improve the performance of other mechanical components such as mechanical seals and heavily loaded journal bearings. Given these demonstrated benefits, capable and economical methods for the production of mechanical components with near-mirror quality surfaces are desired. One could propose the production of near-mirror quality surfaces by several methods such as abrasive polishing, chemical assisted polishing, or grinding. Production of the surfaces by grinding offers the possibility to control the macro-geometry (form), waviness, and surface texture with one process. The present study was carried out to investigate the possibility of producing near-mirror quality surfaces by grinding. The present study makes use of a specially designed grinding machine spindle to improve the surface quality relative to the quality produced when using a spindle of conventional design.

  18. Comparison of High-Speed Operating Characteristics of Size 215 Cylindrical-Roller Bearings as Determined in Turbojet Engine and in Laboratory Test Rig

    NASA Technical Reports Server (NTRS)

    Macks, E Fred; Nemeth, Zolton N

    1951-01-01

    A comparison of the operating characteristics of 75-millimeter-bore (size 215) cylindrical-roller one-piece inner-race-riding cage-type bearings was made using a laboratory test rig and a turbojet engine. Cooling correlation parameters were determined by means of dimensional analysis, and the generalized results for both the inner- and outer-race bearing operating temperatures are compared for the laboratory test rig and the turbojet engine. Inner- and outer-race cooling-correlation curves were obtained for the turbojet-engine turbine-roller bearing with the same inner- and outer-race correlation parameters and exponents as those determined for the laboratory test-rig bearing. The inner- and outer-race turbine roller-bearing temperatures may be predicted from a single curve, regardless of variations in speed, load, oil flow, oil inlet temperature, oil inlet viscosity, oil-jet diameter or any combination of these parameters. The turbojet-engine turbine-roller-bearing inner-race temperatures were 30 to 60 F greater than the outer-race-maximum temperatures, the exact values depending on the operating condition and oil viscosity; these results are in contrast to the laboratory test-rig results where the inner-race temperatures were less than the outer-race-maximum temperatures. The turbojet-engine turbine-roller bearing, maximum outer-race circumferential temperature variation was approximately 30 F for each of the oils used. The effect of oil viscosity on inner- and outer-race turbojet-engine turbine-roller-bearing temperatures was found to be significant. With the lower viscosity oil (6x10(exp -7) reyns (4.9 centistokes) at 100 F; viscosity index, 83), the inner-race temperature was approximately 30 to 35 F less than with the higher viscosity oil (53x10(exp -7) reyns (42.8 centistokes) at 100 F; viscosity index, 150); whereas the outer-race-maximum temperatures were 12 to 28 F lower with the lower viscosity oil over the DN range investigated.

  19. Temperature prediction in high speed bone grinding using motor PWM signal.

    PubMed

    Tai, Bruce L; Zhang, Lihui; Wang, Anthony C; Sullivan, Stephen; Wang, Guangjun; Shih, Albert J

    2013-10-01

    This research explores the feasibility of using motor electrical feedback to estimate temperature rise during a surgical bone grinding procedure. High-speed bone grinding is often used during skull base neurosurgery to remove cranial bone and approach skull base tumors through the nasal corridor. Grinding-induced heat could propagate and potentially injure surrounding nerves and arteries, and therefore, predicting the temperature in the grinding region would benefit neurosurgeons during the operation. High-speed electric motors are controlled by pulse-width-modulation (PWM) to alter the current input and thus maintain the rotational speed. Assuming full mechanical to thermal power conversion in the grinding process, PWM can be used as feedback for heat generation and temperature prediction. In this study, the conversion model was established from experiments under a variety of grinding conditions and an inverse heat transfer method to determine heat flux. Given a constant rotational speed, the heat conversion was represented by a linear function, and could predict temperature from the experimental data with less than 20% errors. Such results support the advance of this technology for practical application. PMID:23806419

  20. Virtual Sensors for On-line Wheel Wear and Part Roughness Measurement in the Grinding Process

    PubMed Central

    Arriandiaga, Ander; Portillo, Eva; Sánchez, Jose A.; Cabanes, Itziar; Pombo, Iñigo

    2014-01-01

    Grinding is an advanced machining process for the manufacturing of valuable complex and accurate parts for high added value sectors such as aerospace, wind generation, etc. Due to the extremely severe conditions inside grinding machines, critical process variables such as part surface finish or grinding wheel wear cannot be easily and cheaply measured on-line. In this paper a virtual sensor for on-line monitoring of those variables is presented. The sensor is based on the modelling ability of Artificial Neural Networks (ANNs) for stochastic and non-linear processes such as grinding; the selected architecture is the Layer-Recurrent neural network. The sensor makes use of the relation between the variables to be measured and power consumption in the wheel spindle, which can be easily measured. A sensor calibration methodology is presented, and the levels of error that can be expected are discussed. Validation of the new sensor is carried out by comparing the sensor's results with actual measurements carried out in an industrial grinding machine. Results show excellent estimation performance for both wheel wear and surface roughness. In the case of wheel wear, the absolute error is within the range of microns (average value 32 μm). In the case of surface finish, the absolute error is well below Ra 1 μm (average value 0.32 μm). The present approach can be easily generalized to other grinding operations. PMID:24854055

  1. Design and fundamental understanding of Minimum Quantity Lubrication (MQL) assisted grinding using advanced nanolubricants

    NASA Astrophysics Data System (ADS)

    Kalita, Parash

    Abrasive grinding is widely used across manufacturing industry for finishing parts and components requiring smooth superficial textures and precise dimensional tolerances and accuracy. Unlike any other machining operations, the complex thermo-mechanical processes during grinding produce excessive friction-induced energy consumption, heat, and intense contact seizures. Lubrication and cooling from grinding fluids is crucial in minimizing the deleterious effects of friction and heat to maximize the output part quality and process efficiency. The conventional flood grinding approach of an uneconomical application of large quantities of chemically active fluids has been found ineffective to provide sufficient lubrication and produces waste streams and pollutants that are hazardous to human health and environment. Application of Minimum Quantity Lubrication (MQL) that cuts the volumetric fluid consumption by 3-4 orders of magnitude have been extensively researched in grinding as a high-productivity and environmentally-sustainable alternative to the conventional flood method. However, the lubrication performance and productivity of MQL technique with current fluids has been critically challenged by the extreme thermo-mechanical conditions of abrasive grinding. In this research, an MQL system based on advanced nanolubricants has been proposed to address the current thermo-mechanical challenges of MQL grinding and improve its productivity. The nanolubricants were composed of inorganic Molybdenum Disulphide nanoparticles (≈ 200 nm) intercalated with organic macromolecules of EP/AW property, dispersed in straight (base) oils---mineral-based paraffin and vegetable-based soybean oil. After feasibility investigations into the grindability of cast iron using MQL with nanolubricants, this research focused on the fundamental understanding of tribological behavior and lubricating mechanisms of nanolubricants as a method to improve the productivity of MQL-assisted surface grinding

  2. Utilisation of chip thickness models in grinding

    NASA Astrophysics Data System (ADS)

    Singleton, Roger

    Grinding is now a well established process utilised for both stock removal and finish applications. Although significant research is performed in this field, grinding still experiences problems with burn and high forces which can lead to poor quality components and damage to equipment. This generally occurs in grinding when the process deviates from its safe working conditions. In milling, chip thickness parameters are utilised to predict and maintain process outputs leading to improved control of the process. This thesis looks to further the knowledge of the relationship between chip thickness and the grinding process outputs to provide an increased predictive and maintenance modelling capability. Machining trials were undertaken using different chip thickness parameters to understand how these affect the process outputs. The chip thickness parameters were maintained at different grinding wheel diameters for a constant productivity process to determine the impact of chip thickness at a constant material removal rate.. Additional testing using a modified pin on disc test rig was performed to provide further information on process variables. The different chip thickness parameters provide control of different process outputs in the grinding process. These relationships can be described using contact layer theory and heat flux partitioning. The contact layer is defined as the immediate layer beneath the contact arc at the wheel workpiece interface. The size of the layer governs the force experienced during the process. The rate of contact layer removal directly impacts the net power required from the system. It was also found that the specific grinding energy of a process is more dependent on the productivity of a grinding process

  3. Cooling effectiveness of cutting fluid in creep feed grinding

    SciTech Connect

    Wang, S.B.; Kou, H.S.

    1997-10-01

    In this study, the heat transfer paths among the grinding fluid, the grains and the workpiece are investigated for the creep feed grinding. As heat enters the workpiece, the majority of heat is carried away by the fluid. Thus, the cooling effectiveness of the grinding fluid is defined and calculated through the application of the numerical method to illustrate how much the fraction of the heat is carried away by the grinding fluid. The results reveal that water has higher cooling effectiveness than oil. In addition, the cooling effect of the grinding fluid becomes more significant at lower workpiece speed, higher grinding depth and greater wheel speed.

  4. Surface integrity on grinding of gamma titanium aluminide intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Murtagian, Gregorio Roberto

    Gamma-TiAl is an ordered intermetallic compound characterized by high strength to density ratio, good oxidation resistance, and good creep properties at elevated temperatures. However, it is intrinsically brittle at room temperature. This thesis investigates the potential for the use of grinding to process TiAl into useful shapes. Grinding is far from completely understood, and many aspects of the individual mechanical interactions of the abrasive grit with the material and their effect on surface integrity are unknown. The development of new synthetic diamond superabrasives in which shape and size can be controlled raises the question of the influence of those variables on the surface integrity. The goal of this work is to better understand the fundamentals of the abrasive grit/material interaction in grinding operations. Experimental, analytical, and numerical work was done to characterize and predict the resultant deformation and surface integrity on ground lamellar gamma-TiAl. Grinding tests were carried out, by analyzing the effects of grit size and shape, workpiece speed, wheel depth of cut, and wear on the subsurface plastic deformation depth (PDD). A practical method to assess the PDD is introduced based on the measurement of the lateral material flow by 3D non-contact surface profilometry. This method combines the quantitative capabilities of the microhardness measurement with the sensitivity of Nomarski microscopy. The scope and limitations of this technique are analyzed. Mechanical properties were obtained by quasi-static and split Hopkinson bar compression tests. Residual stress plots were obtained by x-ray, and surface roughness and cracking were evaluated. The abrasive grit/material interaction was accounted by modeling the force per abrasive grit for different grinding conditions, and studying its correlation to the PDD. Numerical models of this interaction were used to analyze boundary conditions, and abrasive size effects on the PDD. An explicit 2D

  5. Analysis on the grinding quality of palm oil fibers by using combined grinding equipment

    NASA Astrophysics Data System (ADS)

    Gan, H. L.; Gan, L. M.; Law, H. C.

    2015-12-01

    As known, Malaysia is the second largest palm oil producer worldwide after Indonesia, therefore indicating the abundance of its wastes within the country. The plantation would be seen to increase to at least 5.2 million ha by 2020, and the waste generation would be 50-70 times the plantation. However, the efficiency of bulk density is reduced. This is one of the main reasons of the initiation of this size reduction/ grinding research. With appropriate parameters, grinding will be seen to be helping in enhancing the inter-particle bindings, subsequently increasing the quality of final products. This paper focuses on the grinding quality involving palm oil wastes by using the Scanning Electron Microscope (SEM). The samples would first be ground to powder at varying grinding speed and finally got the randomly chosen particles measured to obtain the size range. The grinding speed was manipulated from 15 Hz to 40 Hz. From the data obtained, it was found the particles fineness increased with increasing grinding speed. In general, the size ranged from 45 μm to about 600 μm, where the finest was recorded at the speed of 40 Hz. It was also found that the binding was not so encouraging at very low speeds. Therefore, the optimum grinding speed for oil palm residues lied in the range of 25 Hz to 30 Hz. However, there were still limitations to be overcome if the accuracy of the image clarity is to be enhanced.

  6. Creep-feed grinding: A modern variant of the plane surface grinding process

    NASA Astrophysics Data System (ADS)

    Koenig, W.; Laeur-Schmaltz, H.

    1982-07-01

    Creep feed and conventional grinding are compared. Specifications for an automated combined plane surface - creep feed grinder are presented. It must be possible to preprogram two different grinding cycles with an intervening dressing cycles. The automatic grinder must be equipped with a rigid feed system for the two-stage process, which can provide a steplessly controlled, stick-slip - free workpiece speed over the range 0.01 to 30 m/min. Spindle drive and spindle bearings are to be adapted to the increased demands placed on the machine system by the plungecut grinding technique. An efficient coolant system must be available to provide high pressures and throughput quantities.

  7. Application of cryogenic grinding to achieve homogenization of transuranic wastes

    SciTech Connect

    Atkins, W.H.; Hill, D.D.; Lucero, M.E.; Jaramillo, L.; Martinez, H.E.

    1996-08-01

    This paper describes work done at Los Alamos National Laboratory (LANL) in collaboration with the Department of Energy Rocky Flats Field Office (DOE/RFFO) and with the National Institute of Standards and Technology (NIST), Boulder, Colorado. Researchers on this project have developed a method for cryogenic grinding of mixed wastes to homogenize and, thereby, to acquire a representative sample of the materials. There are approximately 220,000 waste drums owned by the Rocky Flats Environmental Technology Site (RFETS)-50,000 at RFETS and 170,000 at the Idaho National Engineering Laboratory. The cost of sampling the heterogeneous distribution of waste in each drum is prohibitive. In an attempt to produce a homogeneous mixture of waste that would reduce greatly the cost of sampling, researchers at NIST and RFETS are developing a cryogenic grinder. The Los Alamos work herein described addresses the implementation issues of the task. The first issue was to ascertain whether samples of the {open_quotes}small particle{close_quotes} mixtures of materials present in the waste drums at RFETS were representative of actual drum contents. Second, it was necessary to determine at what temperature the grinding operation must be performed in order to minimize or to eliminate the release of volatile organic compounds present in the waste. Last, it was essential to evaluate any effect the liquid cryogen might have on the structural integrity and ventilation capacity of the glovebox system. Results of this study showed that representative samples could be and had been obtained, that some release of organics occurred below freezing because of sublimation, and that operation of the cryogenic grinding equipment inside the glovebox was feasible.

  8. Working with the superabrasives industry to optimize tooling for grinding brittle materials

    SciTech Connect

    Taylor, J.S.; Piscotty, M.A.; Blaedel, K.L.; Gray, F.A.

    1996-05-01

    The optics manufacturing industry is undertaking a significant modernization, as computer-numeric-controlled (CNC) equipment is joining or replacing open-loop equipment and hand lapping/polishing on the shop floor. Several prototype CNC lens grinding platforms employing ring tools are undergoing development and demonstration at the Center for Optics Manufacturing in Rochester, NY, and several machine tool companies have CNC product lines aimed at the optics industry. Benefits to using CNC ring tool grinding equipment include: essentially unlimited flexibility in selecting radii of curvature without special radiused tooling, the potential for CIM linkages to CAD workstations, and the cultural shift from craftsmen with undocumented procedures to CNC machine operators employing computerized routines for process control. In recent years, these developments, have inspired a number of US optics companies to invest in CNC equipment and participate in process development activities involving bound diamond tooling. This modernization process,extends beyond large optics companies that have historically embraced advanced equipment, to also include smaller optical shops where a shift to CNC equipment requires a significant company commitment. This paper addresses our efforts to optimize fine grinding wheels to support the new generation of CNC equipment. We begin with a discussion of how fine grinding fits into the optical production process, and then describe an initiative for improving the linkage between optics industry and the grinding wheel industry. For the purposes of this paper, we define fine wheels to have diamond sizes below 20 micrometers, which includes wheels used for what is sometimes called medium grinding (e.g. 10-20 micrometers diamond) and for fine grinding (e.g. 2-4 micrometers diamond).

  9. 30 CFR 57.14115 - Stationary grinding machines.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Stationary grinding machines. 57.14115 Section... and Equipment Safety Devices and Maintenance Requirements § 57.14115 Stationary grinding machines. Stationary grinding machines, other than special bit grinders, shall be equipped with— (a) Peripheral...

  10. 30 CFR 56.14115 - Stationary grinding machines.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Stationary grinding machines. 56.14115 Section... Equipment Safety Devices and Maintenance Requirements § 56.14115 Stationary grinding machines. Stationary grinding machines, other than special bit grinders, shall be equipped with— (a) Peripheral hoods capable...

  11. 30 CFR 56.14115 - Stationary grinding machines.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Stationary grinding machines. 56.14115 Section... Equipment Safety Devices and Maintenance Requirements § 56.14115 Stationary grinding machines. Stationary grinding machines, other than special bit grinders, shall be equipped with— (a) Peripheral hoods capable...

  12. 30 CFR 77.401 - Stationary grinding machines; protective devices.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Stationary grinding machines; protective... OF UNDERGROUND COAL MINES Safeguards for Mechanical Equipment § 77.401 Stationary grinding machines; protective devices. (a) Stationary grinding machines other than special bit grinders shall be equipped...

  13. 30 CFR 56.14115 - Stationary grinding machines.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Stationary grinding machines. 56.14115 Section... Equipment Safety Devices and Maintenance Requirements § 56.14115 Stationary grinding machines. Stationary grinding machines, other than special bit grinders, shall be equipped with— (a) Peripheral hoods capable...

  14. 30 CFR 57.14115 - Stationary grinding machines.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Stationary grinding machines. 57.14115 Section... and Equipment Safety Devices and Maintenance Requirements § 57.14115 Stationary grinding machines. Stationary grinding machines, other than special bit grinders, shall be equipped with— (a) Peripheral...

  15. 30 CFR 57.14115 - Stationary grinding machines.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Stationary grinding machines. 57.14115 Section... and Equipment Safety Devices and Maintenance Requirements § 57.14115 Stationary grinding machines. Stationary grinding machines, other than special bit grinders, shall be equipped with— (a) Peripheral...

  16. 30 CFR 77.401 - Stationary grinding machines; protective devices.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Stationary grinding machines; protective... OF UNDERGROUND COAL MINES Safeguards for Mechanical Equipment § 77.401 Stationary grinding machines; protective devices. (a) Stationary grinding machines other than special bit grinders shall be equipped...

  17. 30 CFR 56.14115 - Stationary grinding machines.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Stationary grinding machines. 56.14115 Section... Equipment Safety Devices and Maintenance Requirements § 56.14115 Stationary grinding machines. Stationary grinding machines, other than special bit grinders, shall be equipped with— (a) Peripheral hoods capable...

  18. 30 CFR 77.401 - Stationary grinding machines; protective devices.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Stationary grinding machines; protective... OF UNDERGROUND COAL MINES Safeguards for Mechanical Equipment § 77.401 Stationary grinding machines; protective devices. (a) Stationary grinding machines other than special bit grinders shall be equipped...

  19. 30 CFR 57.14115 - Stationary grinding machines.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Stationary grinding machines. 57.14115 Section... and Equipment Safety Devices and Maintenance Requirements § 57.14115 Stationary grinding machines. Stationary grinding machines, other than special bit grinders, shall be equipped with— (a) Peripheral...

  20. 30 CFR 75.1723 - Stationary grinding machines; protective devices.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Stationary grinding machines; protective devices. 75.1723 Section 75.1723 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF....1723 Stationary grinding machines; protective devices. (a) Stationary grinding machines other...

  1. 30 CFR 75.1723 - Stationary grinding machines; protective devices.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Stationary grinding machines; protective devices. 75.1723 Section 75.1723 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF....1723 Stationary grinding machines; protective devices. (a) Stationary grinding machines other...

  2. 30 CFR 57.14115 - Stationary grinding machines.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Stationary grinding machines. 57.14115 Section... and Equipment Safety Devices and Maintenance Requirements § 57.14115 Stationary grinding machines. Stationary grinding machines, other than special bit grinders, shall be equipped with— (a) Peripheral...

  3. 30 CFR 75.1723 - Stationary grinding machines; protective devices.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Stationary grinding machines; protective devices. 75.1723 Section 75.1723 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF....1723 Stationary grinding machines; protective devices. (a) Stationary grinding machines other...

  4. Simulation of Mid-Spatials from the Grinding Process

    NASA Astrophysics Data System (ADS)

    Pohl, M.; Börret, R.

    2016-02-01

    This paper focuses on the simulation of the creation of mid-spatial frequencies (mid-spatials) during the grinding process of optical components. The goal is to simulate this generation process and determine the correlating grinding parameters for mid-spatials. On this base, grinding parameters which lead to less mid-spatials could be determined.

  5. 7 CFR 58.726 - Cutting and grinding.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Cutting and grinding. 58.726 Section 58.726... Procedures § 58.726 Cutting and grinding. The trimmed and cleaned cheese should be cut into sections of convenient size to be handled by the grinder or shredder. The grinding and mixing of the blended lots...

  6. GRINDING ROOM AT SOUTHERN DUCTILE CASTING COMPANY, BESSEMER FOUNDRY SHOWING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    GRINDING ROOM AT SOUTHERN DUCTILE CASTING COMPANY, BESSEMER FOUNDRY SHOWING WHEELABORATOR THAT IMPALE SHOT AT TUMBLING CASTINGS TO REMOVE EXCESS SURFACE METALS AND SAND; ANNEALING OVENS TO HEAT CERTAIN CASTINGS TO ACHIEVE A DESIRED CHARACTERISTIC; AND GRINDING WHEELS USED TO REMOVE GATES. - Southern Ductile Casting Company, Grinding & Shipping, 2217 Carolina Avenue, Bessemer, Jefferson County, AL

  7. 7 CFR 58.726 - Cutting and grinding.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Cutting and grinding. 58.726 Section 58.726... Procedures § 58.726 Cutting and grinding. The trimmed and cleaned cheese should be cut into sections of convenient size to be handled by the grinder or shredder. The grinding and mixing of the blended lots...

  8. 7 CFR 58.726 - Cutting and grinding.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Cutting and grinding. 58.726 Section 58.726... Procedures § 58.726 Cutting and grinding. The trimmed and cleaned cheese should be cut into sections of convenient size to be handled by the grinder or shredder. The grinding and mixing of the blended lots...

  9. Grinding Glass Disks On A Belt Sander

    NASA Technical Reports Server (NTRS)

    Lyons, James J., III

    1995-01-01

    Small machine attached to table-top belt sander makes possible to use belt sander to grind glass disk quickly to specified diameter within tolerance of about plus or minus 0.002 in. Intended to be used in place of production-shop glass grinder. Held on driveshaft by vacuum, glass disk rotated while periphery ground by continuous sanding belt.

  10. Physicochemical and grinding characteristics of dragonhead seeds

    NASA Astrophysics Data System (ADS)

    Dziki, D.; Miś, A.; Gładyszewska, B.; Laskowski, J.; Kwiatkowski, S.; Gawlik-Dziki, U.

    2013-12-01

    The results of investigations on the physicochemical and grinding characteristics of Moldavian dragonhead seeds are presented. The data obtained showed that the physical properties (average size, sphericity, surface area, 1 000 seed mass, dynamic angle of repose, coefficient of static friction, and bulk and true densities) of the white and blue form of dragonhead seeds were not significantly different. Both forms of dragonhead showed similar levels of protein (average of 21%), whereas the blue form of dragonhead had a lower fat content (average of 23.1%) and higher mucilage content (13.35%) in comparison to the blue form of seed (24.6 and 9.95%, respectively). Antioxidant capacity of dragonhead seeds was comparable for both forms and averaged about 40%, which corresponded to EC50 values of 0.12 and 0.13 mgml-1 for the white and blue forms, respectively. The grinding material showed similar particle size distribution of ground material for both forms of dragonhead seeds. The lowest values of specific grinding energy were obtained for the white form of dragonhead seeds, those for the blue form were significantly higher. Grinding of dragonhead seeds using a screen 2.0 mm mesh size caused screen hole clogging. This problem did not occur when dragonhead seeds were mixed with wheat grain.

  11. Carving up Word Meaning: Portioning and Grinding

    ERIC Educational Resources Information Center

    Frisson, S.; Frazier, L.

    2005-01-01

    Two eye-tracking experiments investigated the processing of mass nouns used as count nouns and count nouns used as mass nouns. Following Copestake and Briscoe (1995), the basic or underived sense of a word was treated as the input to a derivational rule (''grinding'' or ''portioning'') which produced the derived sense as output. It was…

  12. Precision replenishable grinding tool and manufacturing process

    DOEpatents

    Makowiecki, Daniel M.; Kerns, John A.; Blaedel, Kenneth L.; Colella, Nicholas J.; Davis, Pete J.; Juntz, Robert S.

    1998-01-01

    A reusable grinding tool consisting of a replaceable single layer of abrasive particles intimately bonded to a precisely configured tool substrate, and a process for manufacturing the grinding tool. The tool substrate may be ceramic or metal and the abrasive particles are preferably diamond, but may be cubic boron nitride. The manufacturing process involves: coating a configured tool substrate with layers of metals, such as titanium, copper and titanium, by physical vapor deposition (PVD); applying the abrasive particles to the coated surface by a slurry technique; and brazing the abrasive particles to the tool substrate by alloying the metal layers. The precision control of the composition and thickness of the metal layers enables the bonding of a single layer or several layers of micron size abrasive particles to the tool surface. By the incorporation of an easily dissolved metal layer in the composition such allows the removal and replacement of the abrasive particles, thereby providing a process for replenishing a precisely machined grinding tool with fine abrasive particles, thus greatly reducing costs as compared to replacing expensive grinding tools.

  13. Precision replenishable grinding tool and manufacturing process

    DOEpatents

    Makowiecki, D.M.; Kerns, J.A.; Blaedel, K.L.; Colella, N.J.; Davis, P.J.; Juntz, R.S.

    1998-06-09

    A reusable grinding tool consisting of a replaceable single layer of abrasive particles intimately bonded to a precisely configured tool substrate, and a process for manufacturing the grinding tool are disclosed. The tool substrate may be ceramic or metal and the abrasive particles are preferably diamond, but may be cubic boron nitride. The manufacturing process involves: coating a configured tool substrate with layers of metals, such as titanium, copper and titanium, by physical vapor deposition (PVD); applying the abrasive particles to the coated surface by a slurry technique; and brazing the abrasive particles to the tool substrate by alloying the metal layers. The precision control of the composition and thickness of the metal layers enables the bonding of a single layer or several layers of micron size abrasive particles to the tool surface. By the incorporation of an easily dissolved metal layer in the composition such allows the removal and replacement of the abrasive particles, thereby providing a process for replenishing a precisely machined grinding tool with fine abrasive particles, thus greatly reducing costs as compared to replacing expensive grinding tools. 11 figs.

  14. Automated Inspection And Precise Grinding Of Gears

    NASA Technical Reports Server (NTRS)

    Frint, Harold; Glasow, Warren

    1995-01-01

    Method of precise grinding of spiral bevel gears involves automated inspection of gear-tooth surfaces followed by adjustments of machine-tool settings to minimize differences between actual and nominal surfaces. Similar to method described in "Computerized Inspection of Gear-Tooth Surfaces" (LEW-15736). Yields gears of higher quality, with significant reduction in manufacturing and inspection time.

  15. Smooth brome (Bromus inermis Leyss) response to concrete grinding residue application

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Concrete grinding residue (CGR) is a slurry byproduct created by concrete pavement maintenance operations. The application of CGR to roadside soils is not consistently regulated by state agencies across the United States. Much of this variability in regulation may be due to the lack of science-base...

  16. Electronic BAR Gauge: a customized optical rail profile measurement system for rail-grinding applications

    NASA Astrophysics Data System (ADS)

    Bachinsky, Gordon S.

    1995-06-01

    The dynamic interaction that occurs at the rail/wheel interface of any rail system is significantly influenced by rail and wheel profiles. In an effort to enhance this interaction, railways and transit systems often employ rail grinding as a means to maintain a defined rail profile. The cost to perform this procedure can be very high, sometimes exceeding $DLR25,000 per day for the use of a large grinding machine (with up to 128 grinding motors-each motor being 20 hp or more). Because of this, it is imperative that the work be done efficiently and accurately. In recent years there has been substantial research into the optimization of rail profiles. The National Research Council (NRC) of Canada is one research facility that has generated a unique, precise set of specified profiles for use in heavy-haul railway operations. To implement these profiles in a consistent manner, during rail grinding operations, requires some type of measurement system that provides feedback to the field staff. Up until recently, this has been accomplished with a manual BAR gauge that is fitted with a set of accurate profile templates. The BAR gauge, which initially was fitted with four specified templates, is now equipped with ten such templates. To obtain the full potential of benefits from these profiles requires more precise grinding than that which has been achieved in the past. The other problem with the current manual profile measurement (BAR) method is that it is somewhat slow and cumbersome and the differences between profiles is quite small (i.e. 0.020 inch or less). In order to enhance their rail grinding management support, ARM pursued an automated system that would optically measure rail profiles very fast and accurately from a hy-rail vehicle and compare them with the NRC profiles. Another important feature that was desired in this system was the ability to measure the relative position of one profile with respect to the other (i.e. left versus right rail). Such a system

  17. Study of the potential of three different MgB2 tapes for application in cylindrical coils operating at 20 K

    NASA Astrophysics Data System (ADS)

    Pitel, J.; Kováč, P.; Tropeano, M.; Grasso, G.

    2015-05-01

    The goal of this theoretical study is to illustrate the potential of three different MgB2 tapes, developed by Columbus Superconductors, for application in cylindrical coils. First, the distribution of critical currents and electric fields of individual turns is compared when the winding of the model coil is made with tapes having different Ic(B) and anisotropy values. Second, the influence of the winding geometry on basic parameters of cylindrical coils which consist of a set of pancake coils, such as critical current Icmin, central magnetic field B0 and stored energy E, is analysed. The winding geometry of the coils, i.e. the outer winding radius and the coil length, with the same inner winding radius, was changed from a disc shape to a long thin solenoid in such a way that the overall tape length was held constant, and considered as a parameter. Finally, the winding cross-section of the coil is optimized with respect to the constant tape length in order to reach the maximum central field. The results of calculations show that for a given overall tape length and inner winding radius there exists only one winding geometry which generates the maximum central field. The overall tape length, as a parameter, is changed in a broad range from 500 m to 10 km. All calculations were performed using the experimental data measured at 20 K while the effect of the anisotropy in the Ic(B) characteristic of the short samples is taken into account.

  18. First Grinding of a Rock on Mars

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The round, shallow depression in this image resulted from history's first grinding of a rock on Mars. The rock abrasion tool on NASA's Spirit rover ground off the surface of a patch 45.5 millimeters (1.8 inches) in diameter on a rock called Adirondack during Spirit's 34th sol on Mars, Feb. 6, 2004. The hole is 2.65 millimeters (0.1 inch) deep, exposing fresh interior material of the rock for close inspection with the rover's microscopic imager and two spectrometers on the robotic arm. This image was taken by Spirit's panoramic camera, providing a quick visual check of the success of the grinding. The rock abrasion tools on both Mars Exploration Rovers were supplied by Honeybee Robotics, New York, N.Y.

  19. Cylindrical neutron generator

    DOEpatents

    Leung, Ka-Ngo

    2009-12-29

    A cylindrical neutron generator is formed with a coaxial RF-driven plasma ion source and target. A deuterium (or deuterium and tritium) plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical neutron generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which contain many slots. The plasma generator emanates ions radially over 360.degree. and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired. The plasma generator may be in the center and the neutron target on the outside, or the plasma generator may be on the outside and the target on the inside. In a nested configuration, several concentric targets and plasma generating regions are nested to increase the neutron flux.

  20. Cylindrical neutron generator

    DOEpatents

    Leung, Ka-Ngo

    2008-04-22

    A cylindrical neutron generator is formed with a coaxial RF-driven plasma ion source and target. A deuterium (or deuterium and tritium) plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical neutron generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which contain many slots. The plasma generator emanates ions radially over 360.degree. and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired. The plasma generator may be in the center and the neutron target on the outside, or the plasma generator may be on the outside and the target on the inside. In a nested configuration, several concentric targets and plasma generating regions are nested to increase the neutron flux.

  1. Cylindrical neutron generator

    DOEpatents

    Leung, Ka-Ngo

    2005-06-14

    A cylindrical neutron generator is formed with a coaxial RF-driven plasma ion source and target. A deuterium (or deuterium and tritium) plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical neutron generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which contain many slots. The plasma generator emanates ions radially over 360.degree. and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired. The plasma generator may be in the center and the neutron target on the outside, or the plasma generator may be on the outside and the target on the inside. In a nested configuration, several concentric targets and plasma generating regions are nested to increase the neutron flux.

  2. Cylindrically symmetric wormholes

    SciTech Connect

    Kuhfittig, Peter K.F.

    2005-05-15

    This paper discusses traversable wormholes that differ slightly but significantly from those of the Morris-Thorne type under the assumption of cylindrical symmetry. The throat is a piecewise smooth cylindrical surface resulting in a shape function that is not differentiable at some value. It is proposed that the regular derivative be replaced by a one-sided derivative at this value. The resulting wormhole geometry satisfies the weak energy condition.

  3. The effect of geometry and operation conditions on the performance of a gas-liquid cylindrical cyclone separator with new structure

    NASA Astrophysics Data System (ADS)

    Han, Qing; Zhang, Chi; Xu, Bo; Chen, Jiangping

    2013-07-01

    The hydrodynamic flow behavior, effects of geometry and working conditions of a gas-liquid cylindrical cyclone separator with a new structure are investigated by computational fluid dynamic and experiment. Gas liquid cylindrical cyclone separator is widely used in oil industry, refrigeration system because of its simple structure, high separating efficiency, little maintenance and no moving parts nor internal devices. In this work, a gas liquid cylindrical cyclone separator with new structure used before evaporator in refrigeration system can remove the vapor from the mixture and make evaporator compact by improving its heat exchange efficiency with the lower inlet quality. It also decreases evaporator pressure drop and reduces compressor work. The two pipes are placed symmetrically which makes each of them can be treated as inlet. It means when the fluids flow reverse, the separator performance will not be influence. Four samples with different geometry parameters are tested by experiment with different inlet quality (0.18-0.33), inlet mass flow rate (65-100kg/h). Compared with the experimental data, CFD simulation results show a good agreement. Eulerian multiphase model and Reynolds Stress Turbulence model are applied in the CFD simulation and obtained the inner flow field such as phase path lines, tangential velocity profiles and pressure and volume of fraction distribution contours. The separator body diameter (24, 36, 48mm) and inlet diameter (3.84, 4.8, 5.76mm) decide the maximum tangential velocity which results in the centrifugal force. The tangential velocity profiles are simulated and compared among different models. The higher tangential velocity makes higher quality of gas outlet but high pressure drop at the same time. Decreasing the inlet diameter increases quality of gas outlet pipe and pressure drop. High gas outlet quality is cost at high pressure drop. Increasing of separator diameter makes gas outlet quality increase first and then decrease but

  4. Dressing of diamond grinding wheels by abrasive water jet for freeform optical surface grinding

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Yao, Peng; Li, Chengwu; Huang, Chuanzhen; Wang, Jun; Zhu, Hongtao; Liu, Zengwen

    2014-08-01

    During the ultra-precision grinding of a large aperture mirror made of RB-SiC, the grinding wheel becomes dull rapidly, which will lead to an increase of grinding force and a decrease of grinding ratio. In this paper, diamond grinding sticks were dressed with micro SiC abrasive water jet and water jet. Through single factorial experiments, the influence of jet pressure on the dressing performance was investigated. To analyze and evaluate the effect of dressing quantitatively, the 3D roughness and the wheel topography were measured and compared with laser scanning confocal microscope before and after dressing. The experimental results show that the abrasive grains are well protruded from binder and the distribution of the abrasive grains becomes uniform after dressing by abrasive water jet when the dressing parameters are properly selected. The dressing performance of abrasive water jet is much better than water jet. For dressing ultra-fine grit size wheels, the abrasive size of the jet should be smaller than the wheel grit size to achieve a better result. The jet pressure is an obvious influence factor of the surface topography.

  5. Freeform grinding and polishing with PROSurf

    NASA Astrophysics Data System (ADS)

    Wolfs, Franciscus; Fess, Edward; DeFisher, Scott; Torres, Josh; Ross, James

    2015-10-01

    Recently, the desire to use freeform optics has been increasing, including shapes such as torics and anamorphic aspheres. Freeform optics can be used to expand capabilities of optical systems. They can compensate for limitations in rotationally symmetric optics. These same traits that give freeform optics the ability to improve optical systems also makes them more challenging to manufacture. This holds true for grinding, polishing, and metrology. As freeform optics become more prevalent in the industry, tolerances will become more stringent, requiring deterministic manufacturing processes. To generate freeforms, it is crucial to have control over all aspects of the process. Controlling the surface definition is important for achieving a better surface finish during processing. Metrology will be required to adjust tool paths at various stages in manufacturing. During grinding, metrology will be used to adjust tool positions relative to the nominal tool path to compensate for repeatable machine and tooling error. For polishing, metrology will be used to deterministically adjust dwell relative to the amount of the error in different surface locations, allowing for convergence towards the desired surface at a uniform rate. OptiPro has developed PROSurf, a CAM software package for creating freeform tool paths and applying metrology-based corrections. The software can be used for both grinding and polishing freeform optics. The software has flexibility to allow for different methods of modelling the surface: mathematical equations, solid models, and point clouds. The software is designed to make it easier to manufacture and polish complex freeform optics.

  6. Material and process issues in electrolytic in-process dressing (ELID)-grinding

    NASA Astrophysics Data System (ADS)

    Chen, Hong

    This research covers research and development of the electrolytic in-process dressing (ELID) grinding technology, where material and process issues are systematically investigated. Experiments on anodic oxidation of cast iron and bronze were performed to determine the growth behavior of the oxides on the metals, their structures and mechanical properties. With SEM and optical microscope, a special technique to measure the oxide thickness was also developed. A series of theoretical calculations was carried out to highlight the fact that the localized dissolution of the metals around diamond particle results in exposing the cutting edge for efficient grinding and/or cutting. A model was proposed on the basis of experimental observations and theoretical calculations. It was the first quantitative model that explores the ELID mechanism and could serve guidance to optimize ELID-grinding operations for many applications. This model recognized the key feature of the oxide layer in the process, formulated the dynamic balance between its growth and wear, and emphasized the important role of its nonlinear growth. It not only brought a link between performance and process parameters, but also explained the experimental results and helped ELID-grinding practice. Grinding experiments performed on OPTICAM PM showed that with a proper selection of operation parameters from the proposed model, (1) ELID-grinding improved surface roughness (RMS) a factor of five for Zerodur; (2) Ductile grinding modes were achieved for Zerodur, BK-7 and SF-6; (3) Mirror finish (RMS < 500 A) and low subsurface damage (depth < 1.5 μm) for 4-inch silicon wafers were produced within 5 minutes; and (4) the three requirements of high precision optical grinding were achieved simultaneously on BK-7: high surface accuracy (flatness < 0.15/ /mum), low subsurface damage (depth < 2/ /mum) and good surface finish (RMS < 500 A). An ELID-cutting system was designed and developed. It consists of a modified cut

  7. Aroma recovery from roasted coffee by wet grinding.

    PubMed

    Baggenstoss, J; Thomann, D; Perren, R; Escher, F

    2010-01-01

    Aroma recovery as determined by solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) was compared in coffees resulting from conventional grinding processes, and from wet grinding with cold and hot water. Freshly roasted coffee as well as old, completely degassed coffee was ground in order to estimate the relationship of internal carbon dioxide pressure in freshly roasted coffee with the aroma loss during grinding. The release of volatile aroma substances during grinding was found to be related to the internal carbon dioxide pressure, and wet grinding with cold water was shown to minimize losses of aroma compounds by trapping them in water. Due to the high solubility of roasted coffee in water, the use of wet-grinding equipment is limited to processes where grinding is followed by an extraction step. Combining grinding and extraction by the use of hot water for wet grinding resulted in considerable losses of aroma compounds because of the prolonged heat impact. Therefore, a more promising two-step process involving cold wet grinding and subsequent hot extraction in a closed system was introduced. The yield of aroma compounds in the resulting coffee was substantially higher compared to conventionally ground coffee. PMID:21535580

  8. Influence of grain size on the grinding response of alumina

    SciTech Connect

    Xu, H.H.K.; Wei, L.; Jahanmir, S.

    1996-05-01

    The effect of grain size on the grinding response, i.e., grinding forces, surface roughness, and grinding-induced subsurface damage, is investigated in a series of alumina ceramics with the average grain size ranging from 3 to 35 {micro}m. The grinding forces are measured as a function of depth of cut in surface grinding. It is found that the grinding forces decrease as the grain size is increased from 3 to 9 {micro}m. But at larger grain sizes, the grinding forces are independent of the grain size. Subsurface damage in grinding is observed using a bonded-interface sectioning technique. The subsurface damage is found to consist of intragrain twin/slip bands and intergranular microcracks. The density of grinding-induced subsurface microcracks increases with the grain size. In addition to using optical microscopy on the sections of the ground specimens, a nondestructive thermal wave measurement technique is used directly on the ground surfaces for the detection of grinding-induced subsurface microcracks. The grain size dependence of the microcrack density estimated from the thermal images is found to agree with the results obtained using the bonded-interface technique.

  9. A Wavelet-Based Methodology for Grinding Wheel Condition Monitoring

    SciTech Connect

    Liao, T. W.; Ting, C.F.; Qu, Jun; Blau, Peter Julian

    2007-01-01

    Grinding wheel surface condition changes as more material is removed. This paper presents a wavelet-based methodology for grinding wheel condition monitoring based on acoustic emission (AE) signals. Grinding experiments in creep feed mode were conducted to grind alumina specimens with a resinoid-bonded diamond wheel using two different conditions. During the experiments, AE signals were collected when the wheel was 'sharp' and when the wheel was 'dull'. Discriminant features were then extracted from each raw AE signal segment using the discrete wavelet decomposition procedure. An adaptive genetic clustering algorithm was finally applied to the extracted features in order to distinguish different states of grinding wheel condition. The test results indicate that the proposed methodology can achieve 97% clustering accuracy for the high material removal rate condition, 86.7% for the low material removal rate condition, and 76.7% for the combined grinding conditions if the base wavelet, the decomposition level, and the GA parameters are properly selected.

  10. Grinding tool for making hemispherical bores in hard materials

    DOEpatents

    Duran, E.L.

    1985-04-03

    A grinding tool for forming hemispherical bores in hard materials such as boron carbide. The tool comprises a hemicircular grinding bit, formed of a metal bond diamond matrix, which is mounted transversely on one end of a tubular tool shaft. The bit includes a spherically curved outer edge surface which is the active grinding surface of the tool. Two coolant fluid ports on opposite sides of the bit enable introduction of coolant fluid through the bore of the tool shaft so as to be emitted adjacent the opposite sides of the grinding bit, thereby providing optimum cooling of both the workpiece and the bit.

  11. Observations on the grinding of alumina with variations in belt speed, load, sample rotation, and grinding fluids

    SciTech Connect

    Schwartz, C.J.; Bahadur, S.

    1998-07-01

    The volume of material removed in the grinding of alumina on a diamond-impregnated grinding belt was studied. Four grinding process parameters were tested: belt speed, normal load at the pin's contact surface, sample rotation during grinding, and grinding fluid. The results showed that at low loads the belts speed did not have a significant effect on material removal rates; however, the material removal rate decreased at higher loads combined with higher speeds. It decreased, in particular, when the sample was also rotated. Of the fluids used, the 50% ethylene glycol--50% water mixture produced the highest material removal rates while the lowest were produced by biodegradable soybean oil. The test conditions that produced high temperatures at the contact surface contributed to plowing as opposed to cutting and resulted in reduced material removal rates. The reasons for these variations were investigated by scanning electron microscopy of the surfaces, which revealed evidence of plastic deformation and temperature rise during grinding.

  12. Learning Activity Packets for Grinding Machines. Unit I--Grinding Machines.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This learning activity packet (LAP) is one of three that accompany the curriculum guide on grinding machines. It outlines the study activities and performance tasks for the first unit of this curriculum guide. Its purpose is to aid the student in attaining a working knowledge of this area of training and in achieving a skilled or moderately…

  13. Learning Activity Packets for Grinding Machines. Unit II--Surface Grinding.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This learning activity packet (LAP) is one of three that accompany the curriculum guide on grinding machines. It outlines the study activities and performance tasks for the second unit of this curriculum guide. Its purpose is to aid the student in attaining a working knowledge of this area of training and in achieving a skilled or moderately…

  14. Application of copper nanoparticles as additions to a grinding fluid to increase the quality of grinding of magnetic ceramic materials

    NASA Astrophysics Data System (ADS)

    Krevchik, V. D.; Skryabin, V. A.; Sokolov, A. V.; Men'shova, S. B.; Artemov, I. I.; Prokof'ev, M. V.; Karasev, N. Ya.

    2015-12-01

    The influence of copper nanoparticles in a grinding fluid (GF) used for grinding on the characteristics of the surface layer of ferrite parts and their service properties is studied. Profilograms of the ground surfaces and their roughness are measured. The electromagnetic losses of 10000NN ferrite parts ground in an GF medium with copper nanoparticles are estimated. The use of metal nanoparticles as additions to a grinding fluid is shown to be useful for processing of brittle nonmetallic materials.

  15. On-machine precision preparation and dressing of ball-headed diamond wheel for the grinding of fused silica

    NASA Astrophysics Data System (ADS)

    Chen, Mingjun; Li, Ziang; Yu, Bo; Peng, Hui; Fang, Zhen

    2013-09-01

    In the grinding of high quality fused silica parts with complex surface or structure using ball-headed metal bonded diamond wheel with small diameter, the existing dressing methods are not suitable to dress the ball-headed diamond wheel precisely due to that they are either on-line in process dressing which may causes collision problem or without consideration for the effects of the tool setting error and electrode wear. An on-machine precision preparation and dressing method is proposed for ball-headed diamond wheel based on electrical discharge machining. By using this method the cylindrical diamond wheel with small diameter is manufactured to hemispherical-headed form. The obtained ball-headed diamond wheel is dressed after several grinding passes to recover geometrical accuracy and sharpness which is lost due to the wheel wear. A tool setting method based on high precision optical system is presented to reduce the wheel center setting error and dimension error. The effect of electrode tool wear is investigated by electrical dressing experiments, and the electrode tool wear compensation model is established based on the experimental results which show that the value of wear ratio coefficient K' tends to be constant with the increasing of the feed length of electrode and the mean value of K' is 0.156. Grinding experiments of fused silica are carried out on a test bench to evaluate the performance of the preparation and dressing method. The experimental results show that the surface roughness of the finished workpiece is 0.03 μm. The effect of the grinding parameter and dressing frequency on the surface roughness is investigated based on the measurement results of the surface roughness. This research provides an on-machine preparation and dressing method for ball-headed metal bonded diamond wheel used in the grinding of fused silica, which provides a solution to the tool setting method and the effect of electrode tool wear.

  16. Examining Cylindrical Dice

    ERIC Educational Resources Information Center

    Jones, Dustin L.

    2009-01-01

    The author describes an activity where prospective mathematics teachers made hypotheses about the dimensions of a fair cylindrical die and conducted experiments with different cylinders. He also provides a model that estimates the probability that a cylinder would land on the lateral surface, depending on the height and diameter of the cylinder.…

  17. Dependence of rates of breakage on fines content in wet ball mill grinding

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Anirban

    The following research fundamentally deals with the cause and implications of nonlinearities in breakage rates of materials in wet grinding systems. The innate dependence of such nonlinearities on fines content and the milling environment during wet grinding operations is also tested and observed. Preferential breakage of coarser size fractions as compared to the finer size fractions in a particle population were observed and discussed. The classification action of the pulp was deemed to be the probable cause for such a peculiarity. Ores with varying degrees of hardness and brittleness were used for wet grinding experiments, primarily to test the variations in specific breakage rates as a function of varying hardness. For this research, limestone, quartzite, and gold ore were used. The degree of hardness is of the order of: limestone, quartzite, gold ore. Selection and breakage function parameters were determined in the course of this research. Functional forms of these expressions were used to compare experimentally derived parameter estimates. Force-fitting of parameters was not done in order to examine the realtime behavior of particle populations in wet grinding systems. Breakage functions were established as being invariant with respect to such operating variables like ball load, mill speed, particle load, and particle size distribution of the mill. It was also determined that specific selection functions were inherently dependent on the particle size distribution in wet grinding systems. Also, they were consistent with inputs of specific energy, according to grind time. Nonlinearity trends were observed for 1st order specific selection functions which illustrated variations in breakage rates with incremental inputs of grind time and specific energy. A mean particle size called the fulcrum was noted below which the nonlinearities in the breakage trends were observed. This magnitude of the fulcrum value varied with percent solids and slurry filling, indicating

  18. 30 CFR 56.14115 - Stationary grinding machines.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Stationary grinding machines. 56.14115 Section 56.14115 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Equipment Safety Devices and Maintenance Requirements § 56.14115 Stationary grinding machines....

  19. 30 CFR 75.1723 - Stationary grinding machines; protective devices.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... devices. 75.1723 Section 75.1723 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF....1723 Stationary grinding machines; protective devices. (a) Stationary grinding machines other than special bit grinders shall be equipped with: (1) Peripheral hoods (less than 90° throat openings)...

  20. 30 CFR 75.1723 - Stationary grinding machines; protective devices.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... devices. 75.1723 Section 75.1723 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF....1723 Stationary grinding machines; protective devices. (a) Stationary grinding machines other than special bit grinders shall be equipped with: (1) Peripheral hoods (less than 90° throat openings)...

  1. 7 CFR 58.726 - Cutting and grinding.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Cutting and grinding. 58.726 Section 58.726 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... Procedures § 58.726 Cutting and grinding. The trimmed and cleaned cheese should be cut into sections...

  2. 7 CFR 58.726 - Cutting and grinding.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Cutting and grinding. 58.726 Section 58.726 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... Procedures § 58.726 Cutting and grinding. The trimmed and cleaned cheese should be cut into sections...

  3. Surface-figuring CVD-SiC mirrors with a five-axis-control ultraprecision grinding machine

    NASA Astrophysics Data System (ADS)

    Namba, Yoshiharu; Suzuki, Hiroshi

    1997-11-01

    A large 5-axis control ultraprecision grinding machine has been developed for making synchrotron-radiation mirrors with high accuracy. The positional and angular resolutions of the machine are 10 nm and 0.0002 degree, respectively. The dimensions of the machine are 3.3 m by 2.7 m by 4.4 m in height. The machine can generate non-axisymmetric aspheric surfaces on CVD-SiC material by a disc-type metal-bonded diamond wheel. An electric micrometer has been set near a grinding head for measuring the form error of ground surface in conformity with the machine movement due to the cutter location data. A series of the measured form errors corrects the former cutter location data automatically and the next grinding operation will be performed by the new cutter location data. A CVD-SiC material of 510 mm by 110 mm was ground into a toroidal surface of 750 nm in shape accuracy by the fifth grinding operation with the fourth correction of cutter location data. More than 99% of toroidal surface area have a form accuracy less than 500 nm. 3.3 nm rms surface roughness was obtained by the ultraprecision grinding using a SD4000N150M metal-bonded diamond wheel.

  4. Three-dimensional measurement and characterization of grinding tool topography

    NASA Astrophysics Data System (ADS)

    Cui, Changcai; Blunt, Liam; Jiang, Xiangqian; Xu, Xipeng; Huang, Hui; Ye, Ruifang

    2013-01-01

    A comprehensive 3-dimensional measurement and characterization method for grinding tool topography was developed. A stylus instrument (SOMICRONIC, France) was used to measure the surface of a metal-bonded diamond grinding tool. The sampled data was input the software SurfStand developed by Centre for Precision Technology (CPT) for reconstruction and further characterization of the surface. Roughness parameters pertaining to the general surface and specific feature parameters relating to the grinding grits, such as height and angle peak curvature have been calculated. The methodology of measurement has been compared with that using an optical microscope. The comparison shows that the three-dimensional characterization has distinct advantages for grinding tool topography assessment. It is precise, convenient and comprehensive so it is suitable for precision measurement and analysis where an understanding of the grinding tool and its cutting ability are required.

  5. Dynamical aspects in modeling long cantilevering workpieces in tool grinding

    NASA Astrophysics Data System (ADS)

    de Payrebrune, K. M.; Kröger, M.

    2015-10-01

    Tool grinding is a complex process in which temporal dynamics of workpiece and grinding wheel, and the material removal process itself, affect the quality of the workpiece. Many existing models already provide the option to study the dynamics of workpiece and grinding wheel or cutting forces and material removal processes, but mostly do not combine these aspects. Here, workpiece dynamics are studied in relation to its structural and geometrical changing properties during machining, and are used to simulate the vibrations and deformation of the workpiece during grinding. In combination with models for the grinding wheel and the material removal process, dependencies of the workpiece dynamics on the workpieces quality are studied and results from this hybrid model are in excellent agreement with empirical measurements. Furthermore, the results demonstrate the significant effects of deformations of the workpiece on its final geometry.

  6. Cylindrically symmetric electrohydrodynamic patterning.

    PubMed

    Deshpande, Paru; Pease, Leonard F; Chen, Lei; Chou, Stephen Y; Russel, William B

    2004-10-01

    Cylindrically symmetric structures such as concentric rings and rosettes arise out of thin polymeric films subjected to strong electric fields. Experiments that formed concentric rings and theory capable of explaining these and other cylindrical structures are presented. These rings represent an additional member of a class of structures, including pillars and holes, formed by electrohydrodynamic patterning of thin films, occasionally referred to as lithographically induced self-assembly. Fabrication of a set of concentric rings begins by spin coating a thin poly(methyl methacrylate) film onto a silicon wafer. A mask is superimposed parallel to the film leaving a similarly thin air gap. Electric fields, acting in opposition to surface tension, destabilize the free interface when raised above the glass transition temperature. Central pillars nucleate under small cylindrical protrusions patterned on the mask. Rings then emerge sequentially, with larger systems having as many as 10 fully formed rings. Ring-to-ring spacings and annular widths, typically on the order of a micron, are approximately constant within a concentric cluster. The formation rate is proportional to the viscosity and, consequently, has the expected Williams-Landel-Ferry dependence on temperature. In light of these developments we have undertaken a linear stability analysis in cylindrical coordinates to describe these rings and ringlike structures. The salient feature of this analysis is the use of perturbations that incorporate their radial dependence in terms of Bessel functions as opposed to the traditional sinusoids of Cartesian coordinates. The theory predicts approximately constant ring-to-ring spacings, constant annular widths, and growth rates that agree with experiment. A secondary instability is observed at higher temperatures, which causes the rings to segment into arcs or pillar arrays. The cylindrical theory may be generalized to describe hexagonal pillar/hole packing, gratings, and

  7. Cylindrically polarized nondiffracting optical pulses

    NASA Astrophysics Data System (ADS)

    Ornigotti, Marco; Conti, Claudio; Szameit, Alexander

    2016-07-01

    We extend the concept of radially and azimuthally polarized optical beams to the polychromatic domain by introducing cylindrically polarized nondiffracting optical pulses. In particular, we discuss in detail the case of cylindrically polarized X-waves, both in the paraxial and nonparaxial regime. The explicit expressions for the electric and magnetic fields of cylindrically polarized X-waves are also reported.

  8. Static cylindrically symmetric spacetimes

    NASA Astrophysics Data System (ADS)

    Fjällborg, Mikael

    2007-05-01

    We prove the existence of static solutions to the cylindrically symmetric Einstein Vlasov system, and we show that the matter cylinder has finite extension in two of the three spatial dimensions. The same results are also proved for a quite general class of equations of state for perfect fluids coupled to the Einstein equations, extending the class of equations of state considered by Bicak et al (2004 Class. Quantum Grav.21 1583). We also obtain this result for the Vlasov Poisson system.

  9. Chirality Change by Grinding Crystals in Solution

    SciTech Connect

    Viedma, Cristobal

    2010-07-22

    One of the greatest unsolved problems in chemistry is the origin of homochirality in the biosphere, that is, the fact that l-amino acids and d-sugars dominate in biology, while laboratory experiments with stereoselective reactions only produce racemic mixtures. Several models have been proposed to address the question of how enantiomerically pure solutions or crystalline phases could have emerged from a presumably racemic prebiotic world. Here we show that two populations of amino acid crystals of 'left' and 'right' hand cannot coexist in solution: one of the chiral populations disappears in an irreversible autocatalytic process that nurtures the other one. Final and complete chiral purity seems to be an inexorable fate in our systems, under grinding, in the course of the common process of growth-dissolution. This unexpected chiral symmetry breaking has become firmly established but the underlying mechanism is being debated and we have no definitive answer.

  10. [Automatic grinding of undecalcified bone sections with exact adjustment of thickness].

    PubMed

    Stürmer, K M

    1979-01-01

    A new grinding machine for preparing thin undecalcified bone sections after methylmethacrylate embedding is described. About 20 rather small bone sections can be ground at the same time; bigger specimens, up to 8 cm of length, are allowed. Bone sections are mounted on a cylindrical specimen holder by an adhesive film. Then the final thickness of the sections is exactly adjusted by screwing three rubies out of the holder's bottom. Now the prepared holder is set in a guide ring on a turntable carrying a rough ended glass plate. The desired thickness of the sections is reached as soon as the three rubies touch the glass surface. The variation in the thickness of the sections is less than +/- 3 micron. The machine is simply constructed, easily to handle and rapidly to clean. PMID:371325

  11. Cylindrical optic figuring dwell time optimization

    NASA Astrophysics Data System (ADS)

    Waluschka, Eugene

    2000-11-01

    The Constellation-X, grazing incidence, x-ray telescope may be fabricated from replicated segments. A series of mandrels will serve as the 'masters' in the replication processes. Diamond turning (milling) followed by abrasive figuring followed by a super polishing are the steps currently envisioned in making just one (of many) mandrel. The abrasive figuring of a mandrel is accomplished by moving a grinding tool along a helical path on this almost cylindrical surface. The measurement of the surface is, however, performed along 'axial' scan lines which intercept this helical path. This approach to figuring and measuring permits a relatively simple scheme to be implemented for the determination of the optimal dwell times of the figuring tool. These optimal dwell times are determined by a deconvolution which approaches the problem in a linear programming context and uses the Simplex Method. The approach maximizes the amount of material removed at any point subject to inequality constraints. The effects of using these 'optimum' dwell times is to significantly improve the tools effectiveness at removing the higher spatial frequencies while staying (strictly) within the bounds and constraints imposed by the hardware. In addition, the ringing at the edges of the optic, frequently present in deconvolution problems, is completely eliminated.

  12. Technological Aspects of Forming the Surface Microrelief of Low-Wear Coatings after Electro-Diamond Grinding

    NASA Astrophysics Data System (ADS)

    Burov, V. G.; Yanpolskiy, V. V.; Rakhimyanov, K. Kh

    2016-04-01

    The results of electro-diamond grinding of coatings based on the WC25 powder material are presented in the paper. It is shown that after electro-diamond grinding of the WC25 coating, an obtained magnitude (Ra=2.02µm) of surface roughness doesn’t meet the qualifying standards to parts surface working in wear-out conditions. The forming of the obtained microrelief is probably connected to the features of electrochemical dissolution of the WC25 coating material in the electrolyte being used. Based on the polarization studies, it is revealed that the electrochemical dissolution character of the indicated coating in the water solution of 10%NaNO3 is determined by the dissolution character of cobalt (Co) component. The intensive cobalt (Co) dissolution during the electro-diamond grinding of the WC25 coating leads to the tungsten carbide chipping by the grinding disk particles that increases the roughness. One of the way to improve the surface quality of low-wear coatings after electro-diamond grinding is an introduction of an additional step in a technological process, carrying out with the switched off source of technological current. For realization of the process according to this scheme a technological dimension chain is made which takes into consideration the dissolution value of the most active coating composition element while the calculating of the operating dimensions of a detail.

  13. Conformal approach to cylindrical DLA

    NASA Astrophysics Data System (ADS)

    Taloni, A.; Caglioti, E.; Loreto, V.; Pietronero, L.

    2006-09-01

    We extend the conformal mapping approach elaborated for the radial diffusion limited aggregation model (DLA) to cylindrical geometry. We introduce in particular a complex function which allows a cylindrical cluster to be grown using as an intermediate step a radial aggregate. The aggregate grown exhibits the same self-affine features as the original cylindrical DLA. The specific choice of the transformation allows us to study the relationship between the radial and the cylindrical geometry. In particular the cylindrical aggregate can be seen as a radial aggregate with particles of size increasing with the radius. On the other hand, the radial aggregate can be seen as a cylindrical aggregate with particles of size decreasing with the height. This framework, which shifts the point of view from the geometry to the size of the particles, can open the way to more quantitative studies on the relationship between radial and cylindrical DLA.

  14. Ultrafine grinding of low-rank coal: Final report

    SciTech Connect

    Bouchillon, C.W.; Steele, W.G.

    1986-08-01

    A study of ultrafine grinding of low-rank coals in a fluid-energy mill was undertaken. This report presents the results of the Phase I effort which included a review of the literature on ultrafine grinding, a review of theories of grinding, a combined grinding and drying experiment on Martin Lake Texas lignite, an evaluation of the energy requirements for the process, and an evaluation of the properties of the products from the grinding tests. A sample of Martin Lake Texas lignite was obtained and a series of tests were conducted in a fluid-energy mill at the Ergon, Inc., Micro-Energy Division development facility at Vicksburg, MS. The grinding fluids used were air at 116 F and steam at 225, 310, 350, 400, and 488 F as measured in the mill. The products of these tests were analyzed for volatile mattr, ash, total moisture, equilibrium moisture, heating value, density distribution, aerodynamic particle size classification, angle of repose, porosity, density, and particle size distribution. ASTM test procedures were followed where applicable. Ultimate and ash mineral analyses were also conducted on the samples. Results of the various tests are presented in detail in the report. In general, the fluid energy mill was used succssfully in simultaneous grinding and drying of the lignite. Particle size reduction to less than 10 microns on a population basis was achieved. The equilibrium moisture of the samples decreased with increasing grinding fluid temperatures. Density distribution studies showed that a significant fraction of the ash appeared in the >1.6 specific gravity particles. The energy required for the grinding/drying process increased with increasing mill temperatures. 29 refs., 18 figs., 13 tabs.

  15. Effect of wet grinding on structural properties of ball clay

    SciTech Connect

    Purohit, A. Chander, S.; Dhaka, M. S.; Hameed, A.; Singh, P.; Nehra, S. P.

    2015-05-15

    In this paper, the effect of wet grinding on structural properties of ball clay is undertaken. The wet grinding treatment was performed employing ball and vibro mills for different time spells of 2, 4, 8 and 16 hours. The structural properties were carried out using X-ray diffraction (XRD). The structure of ground samples is found to be simple cubic. The crystallographic parameters are calculated and slight change in lattice constant, inter planner spacing and particle size is observed with grinding treatment. The results are in agreement with the available literature.

  16. Cryogenic grinding technology for traditional Chinese herbal medicine

    NASA Astrophysics Data System (ADS)

    Li, Shimo; Ge, Shuangyan; Huang, Zhongping; Wang, Qun; Zhao, Haoping; Pan, Huaiyu

    The fundamental principle of cryogenic grinding (cryogrinding) for Chinese herbal medicine is similar to that of grinding methods for conventional materials, but the compositions are very complex, containing aromatics of high volatility, oils and fats, which are easily oxidized. Using liquid nitrogen or liquid air as the cryogen, all of these thermosensitive Chinese herbal medicines can be ground below their brittle temperature. The colour and other properties of the products of cryo-grinding will not be changed and the flavour and nutrition of the medicines will not be lost.

  17. Grinding Wheel Condition Monitoring with Hidden Markov Model-Based Clustering Methods

    SciTech Connect

    Liao, T. W.; Hua, G; Qu, Jun; Blau, Peter Julian

    2006-01-01

    Hidden Markov model (HMM) is well known for sequence modeling and has been used for condition monitoring. However, HMM-based clustering methods are developed only recently. This article proposes a HMM-based clustering method for monitoring the condition of grinding wheel used in grinding operations. The proposed method first extract features from signals based on discrete wavelet decomposition using a moving window approach. It then generates a distance (dissimilarity) matrix using HMM. Based on this distance matrix several hierarchical and partitioning-based clustering algorithms are applied to obtain clustering results. The proposed methodology was tested with feature sequences extracted from acoustic emission signals. The results show that clustering accuracy is dependent upon cutting condition. Higher material removal rate seems to produce more discriminatory signals/features than lower material removal rate. The effect of window size, wavelet decomposition level, wavelet basis, clustering algorithm, and data normalization were also studied.

  18. Angular analysis of the cyclic impacting oscillations in a robotic grinding process

    NASA Astrophysics Data System (ADS)

    Rafieian, Farzad; Girardin, François; Liu, Zhaoheng; Thomas, Marc; Hazel, Bruce

    2014-02-01

    In a robotic machining process, a light-weight cutter or grinder is usually held by an articulated robot arm. Material removal is achieved by the rotating cutting tool while the robot end effector ensures that the tool follows a programmed trajectory in order to work on complex curved surfaces or to access hard-to-reach areas. One typical application of such process is maintenance and repair work on hydropower equipment. This paper presents an experimental study of the dynamic characteristics of material removal in robotic grinding, which is unlike conventional grinding due to the lower structural stiffness of the tool-holder robot. The objective of the study is to explore the cyclic nature of this mechanical operation to provide the basis for future development of better process control strategies. Grinding tasks that minimize the number of iterations to converge to the target surface can be better planned based on a good understanding and modeling of the cyclic material removal mechanism. A single degree of freedom dynamic analysis of the process suggests that material removal is performed through high-frequency impacts that mainly last for only a small fraction of the grinding disk rotation period. To detect these discrete cutting events in practice, a grinder is equipped with a rotary encoder. The encoder's signal is acquired through the angular sampling technique. A running cyclic synchronous average is applied to the speed signal to remove its non-cyclic events. The measured instantaneous rotational frequency clearly indicates the impacting nature of the process and captures the transient response excited by these cyclic impacts. The technique also locates the angular positions of cutting impacts in revolution cycles. It is thus possible to draw conclusions about the cyclic nature of dynamic changes in impact-cutting behavior when grinding with a flexible robot. The dynamics of the impacting regime and transient responses to impact-cutting excitations

  19. Grinding methods to enhance the reactivity of olivine

    SciTech Connect

    Summers, Cathy A.; Dahlin, David C.; Rush, Gilbert E.; O'Connor, William K.; Gerdemann, Stephen J.

    2005-08-01

    The Albany Research Center (ARC) conducted studies of mechanical activation by conventional and ultrafine grinding techniques to enhance olivine reactivity in mineral carbonation reactions. Activated olivine is one of several solid feed materials used at ARC in reactions with carbon dioxide to form carbonate minerals. This paper compares grinding techniques via energy demand data and product characteristics, including particle size distributions, surface areas, full-width-at-half-maximum (FWHM) XRD analyses, and particle morphology by SEM analyses. Reactivity was calculated by percent conversion to carbonate in subsequent carbonation tests. Particle size reduction has the greatest impact on reactivity, and wet grinding is more energy efficient than dry grinding. Large additional inputs of energy to increase surface area or reduce crystallinity do not result in proportional improvements in reactivity.

  20. DETAIL OF SPARE CONICAL CRUSHER AND GRINDING BURR WHEELS REMOVED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL OF SPARE CONICAL CRUSHER AND GRINDING BURR WHEELS REMOVED FROM THE MILLING MACHINE. - F. & H. Benning Company Oyster Mill, 14430 Solomons Island Road (moved from 1014 Benning Road, Galesville, Anne Arundel County, Maryland), Solomons, Calvert County, MD

  1. 66. BUILDING NO. 554, REWORK POWDER GRINDING ROUSE, PULVERIZING, WATER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    66. BUILDING NO. 554, REWORK POWDER GRINDING ROUSE, PULVERIZING, WATER DRY HOUSE, LOOKING NORTH (DEMOLITION IN PROGRESS). - Picatinny Arsenal, 500 Area, Powder Factory & Power House, State Route 15 near I-80, Dover, Morris County, NJ

  2. 41. PATTERN STORAGE, GRIND STONE, WATER TANK, SHAFTING, AND TABLE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    41. PATTERN STORAGE, GRIND STONE, WATER TANK, SHAFTING, AND TABLE SAW (L TO R)-LOOKING WEST. - W. A. Young & Sons Foundry & Machine Shop, On Water Street along Monongahela River, Rices Landing, Greene County, PA

  3. Measurement of cylindrical parts

    NASA Astrophysics Data System (ADS)

    Knight, Paul Douglas, Jr.

    The form of cylindrical parts has been traditionally evaluated using stylus-based mechanical instruments. The Tropel Corporation has developed a grazing incidence interferometer (GII) for the measurement of cylindrical parts. The repeatability of this instrument due to various instrument uncertainties was measured. Differing instrument configurations that produce the same systematic error were determined to produce a zonal calibration method for determining systematic error over the full range of the instrument, given knowledge of the error in a single zone. The effect of the aperture stop on the response of the imaging system to axially sinusoidal artifacts was simulated. Diamond-turned axially sinusoidal artifacts, with amplitude of order1 um and spatial wavelength of order10 mm, were measured to test the axial response of the interferometer. The modulation transfer function of the instrument's imaging system, measured using a knife edge test, predicts the response observed with the sinusoidal artifacts. A diffraction analysis predicts that the measured axial form is modified by a second order envelope function with phase that varies with the relative position of the imaging system focal plane and part position. A compensation method is proposed for this effect. A comparison of roundness measurements by both a traditional stylus-based instrument and the GII was performed demonstrating that the roundness measurements of the two instruments are equivalent when the measurements are properly corrected for the differing effects of surface finish.

  4. Cylindrical laser welder

    NASA Astrophysics Data System (ADS)

    Honeycutt, T. E.; Roberts, T. G.

    1986-05-01

    Brass retainer rings are currently fastened to artillery shells by spinning each shell at a high rate and then jamming the ring on it so that it is fastened or welded by friction between the two objects. This is an energy-inefficient process which heats and weakens more material than is desirable. The shell spinning at a high rate is also potentially dangerous. A laser welder is provided that generates output energy focused on a circular or cylindrical shape for simultaneously welding around a 360 degs circumference without unnecessarily heating large amounts of material. The welder may be used to fasten cylindrical shaped objects, gears and shafts together, which is difficult to do by conventional means. The welder may also be used to fasten one cylinder to another. To accomplish the welding, a laser has an unstable optical cavity arranged with its feedback mirror centered to generate a circular output beam having an obscuration in the center. A circularly-symmetric, off-axis concave mirror focuses the output beam onto the objects being fastened and away from the center line or axis of the circular beam.

  5. Cup Cylindrical Waveguide Antenna

    NASA Technical Reports Server (NTRS)

    Acosta, Roberto J.; Darby, William G.; Kory, Carol L.; Lambert, Kevin M.; Breen, Daniel P.

    2008-01-01

    The cup cylindrical waveguide antenna (CCWA) is a short backfire microwave antenna capable of simultaneously supporting the transmission or reception of two distinct signals having opposite circular polarizations. Short backfire antennas are widely used in mobile/satellite communications, tracking, telemetry, and wireless local area networks because of their compactness and excellent radiation characteristics. A typical prior short backfire antenna contains a half-wavelength dipole excitation element for linear polarization or crossed half-wavelength dipole elements for circular polarization. In order to achieve simultaneous dual circular polarization, it would be necessary to integrate, into the antenna feed structure, a network of hybrid components, which would introduce significant losses. The CCWA embodies an alternate approach that entails relatively low losses and affords the additional advantage of compactness. The CCWA includes a circular cylindrical cup, a circular disk subreflector, and a circular waveguide that serves as the excitation element. The components that make it possible to obtain simultaneous dual circular polarization are integrated into the circular waveguide. These components are a sixpost polarizer and an orthomode transducer (OMT) with two orthogonal coaxial ports. The overall length of the OMT and polarizer (for the nominal middle design frequency of 2.25 GHz) is about 11 in. (approximately equal to 28 cm), whereas the length of a commercially available OMT and polarizer for the same frequency is about 32 in. (approximately equal to 81 cm).

  6. Lightweight Tool Grinds Back-Side Weld Beads

    NASA Technical Reports Server (NTRS)

    Gallagher, Robert L.

    1994-01-01

    Air-powered grinder enables high-quality rework of welds. Tool removes excess material from back side of weld in preparation for reworking. Used on workpiece while workpiece still mounted in welding fixture or welding machine. Then rewelded in original position, so full process control maintained. Used for grinding material in spaces to which access limited, such as in pressure vessels and in hulls of ships. Also used to grind materials other than metals.

  7. 65. BUILDING NO. 554, REWORK POWDER GRINDING HOUSE, PULVERIZING, WATER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    65. BUILDING NO. 554, REWORK POWDER GRINDING HOUSE, PULVERIZING, WATER DRY HOUSE, LOOKING SOUTH AT NORTH SIDE (DEMOLITION IN PROGRESS) OF BUILDING ONCE USED FOR REWORK POWDER GRINDING AND PULVERIZING (SEE NJ-36-C-33 FOR DIAGRAM OF THIS RECLAMATION PROCESS). THIS BUILDING ALSO SERVED AS A WATER DRY HOUSE. - Picatinny Arsenal, 500 Area, Powder Factory & Power House, State Route 15 near I-80, Dover, Morris County, NJ

  8. Surface grinding of space materials using specially formulated vitrified grinding wheels

    NASA Astrophysics Data System (ADS)

    Jackson, M. J.; Robinson, G.

    2006-04-01

    The quantum leap that is expected in the reliability and safety of machined engineering components over the next 20 years, especially in the space industries, will require improvements in the quality of cutting tools if science-based manufacturing is the goal for manufacturing by 2020. Significant improvements have been made in the past 10 years by understanding the properties of vitrified bonding systems used to bond conventional and superabrasive materials in grinding tools. The nature of the bonding system is of paramount importance if next-generation cutting tools are to be used for aerospace materials, especially if they are dressed using laser beams.

  9. Grinding aspheric and freeform micro-optical molds

    NASA Astrophysics Data System (ADS)

    Tohme, Yazid E.

    2007-02-01

    Fueled by the need for better performing optics, glass optics are now replacing plastic optics in many industrial and consumer electronic devices. One of these devices is the mobile phone camera. The optical sub-assembly in a mobile phone includes several micro lenses that are spherical and/or aspherical in shape and require form tolerances in the submicron range. These micro glass lenses are mass produced by a replication process known as glass press molding. The process entails the compression of a glass gob between two precise optical quality molds at an elevated temperature, usually near the transition temperature of the glass material. The elevated forces and temperatures required in the glass molding process limits the materials of the molds to very tough materials such as tungsten carbide or silicon carbide. These materials can withstand large pressing forces at high temperatures without any significant deformation. These materials offer great mechanical properties for glass press molding but they are also a challenge to machine to submicron accuracy. The work in this paper discusses a deterministic micro grinding manufacturing process referred to as wheel normal grinding, which is utilized to produce these optical quality molds. Wheel normal grinding is more accurate and more deterministic than most other grinding techniques and can produce molds to the form and finish tolerances required for optical molding. This method relies on the ability to recognize and compensate for grinding wheel wear and machine repeatable errors. Results will be presented to illustrate the accuracy of this micro grinding technique.

  10. A printed circuit cylindrical array antenna

    NASA Astrophysics Data System (ADS)

    Agrawal, Ashok K.; Powell, Walter E.

    1986-11-01

    The design and performance of a Ku-band cylindrical antenna are described. The antenna is designed to provide a 360-deg azimuth coverage with 20-dB sidelobes and an operating bandwidth of 1 GHz (16.0-17.0 GHz). The antenna consists of 16 facets of 2 x 4 dipole arrays. The 360-deg coverage is obtained with a switch matrix network. The antenna elements and the feeding switch matrix network are printed on a single printed circuit board.

  11. Identification and control of grinding processes for intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Razavi, Hosein Ali

    2000-10-01

    An intermetallic compound (IMC) is a combination of two or more metals with a particular atomic formula by having either ionic and covalent bonds, or metallic bonds with specific crystal structures. They may be thought of as the intermediate between metals and ceramics. These new materials may combine the best of each class: the ductility, heat and electric conductivity of metals with the strength and oxidation resistance of ceramics. Previous study has proposed that the depth of plastic deformation can be used as a parameter to describe the influence of grinding conditions on other physical properties of subsurface layers. Accordingly, the indentation model has been developed to correlate the depth of plastic deformation with the normal component of grinding force. It has been reported that the under certain grinding conditions the depth of plastic deformation does not follow the indentation model. The primary objective of this research is to explain such deviations and to demonstrate that this model can be used to control and predict the depth of plastic deformation. Elements of this research include the development of an open architecture platform to study grinding process, a signal processing algorithm for gap elimination, introducing and implementation of model reference unfalsification and learning concept, development of a mathematical model for grinding gamma-TiAl, a comparison between conventional and superabrasive grinding, control and prediction of the depth of plastic deformation, and initiation of one of the first databases for grinding gamma-TiAl. This work not only serves as a step toward the use of IMCs in future technology but also serves as a step toward autonomous machining systems using intelligent control and advanced monitoring which is a feature of the future abrasive technology.

  12. Stage Cylindrical Immersive Display

    NASA Technical Reports Server (NTRS)

    Abramyan, Lucy; Norris, Jeffrey S.; Powell, Mark W.; Mittman, David S.; Shams, Khawaja S.

    2011-01-01

    Panoramic images with a wide field of view intend to provide a better understanding of an environment by placing objects of the environment on one seamless image. However, understanding the sizes and relative positions of the objects in a panorama is not intuitive and prone to errors because the field of view is unnatural to human perception. Scientists are often faced with the difficult task of interpreting the sizes and relative positions of objects in an environment when viewing an image of the environment on computer monitors or prints. A panorama can display an object that appears to be to the right of the viewer when it is, in fact, behind the viewer. This misinterpretation can be very costly, especially when the environment is remote and/or only accessible by unmanned vehicles. A 270 cylindrical display has been developed that surrounds the viewer with carefully calibrated panoramic imagery that correctly engages their natural kinesthetic senses and provides a more accurate awareness of the environment. The cylindrical immersive display offers a more natural window to the environment than a standard cubic CAVE (Cave Automatic Virtual Environment), and the geometry allows multiple collocated users to simultaneously view data and share important decision-making tasks. A CAVE is an immersive virtual reality environment that allows one or more users to absorb themselves in a virtual environment. A common CAVE setup is a room-sized cube where the cube sides act as projection planes. By nature, all cubic CAVEs face a problem with edge matching at edges and corners of the display. Modern immersive displays have found ways to minimize seams by creating very tight edges, and rely on the user to ignore the seam. One significant deficiency of flat-walled CAVEs is that the sense of orientation and perspective within the scene is broken across adjacent walls. On any single wall, parallel lines properly converge at their vanishing point as they should, and the sense of

  13. Low-Rank Coal Grinding Performance Versus Power Plant Performance

    SciTech Connect

    Rajive Ganguli; Sukumar Bandopadhyay

    2008-12-31

    The intent of this project was to demonstrate that Alaskan low-rank coal, which is high in volatile content, need not be ground as fine as bituminous coal (typically low in volatile content) for optimum combustion in power plants. The grind or particle size distribution (PSD), which is quantified by percentage of pulverized coal passing 74 microns (200 mesh), affects the pulverizer throughput in power plants. The finer the grind, the lower the throughput. For a power plant to maintain combustion levels, throughput needs to be high. The problem of particle size is compounded for Alaskan coal since it has a low Hardgrove grindability index (HGI); that is, it is difficult to grind. If the thesis of this project is demonstrated, then Alaskan coal need not be ground to the industry standard, thereby alleviating somewhat the low HGI issue (and, hopefully, furthering the salability of Alaskan coal). This project studied the relationship between PSD and power plant efficiency, emissions, and mill power consumption for low-rank high-volatile-content Alaskan coal. The emissions studied were CO, CO{sub 2}, NO{sub x}, SO{sub 2}, and Hg (only two tests). The tested PSD range was 42 to 81 percent passing 76 microns. Within the tested range, there was very little correlation between PSD and power plant efficiency, CO, NO{sub x}, and SO{sub 2}. Hg emissions were very low and, therefore, did not allow comparison between grind sizes. Mill power consumption was lower for coarser grinds.

  14. New optical cylindrical microresonators

    NASA Astrophysics Data System (ADS)

    Gun'ko, Yurii K.; Balakrishnan, Sivakumar; McCarthy, Joseph E.; Rakovich, Yuri P.; Donegan, John F.; Perova, Tatiana S.; Melnikov, Vasily

    2007-10-01

    In this paper we describe a novel technique for the fabrication of aluminosilicate microfibres and microtubes which are shown to act as optical cylindrical microresonators. The alumosilicate microfibres and microtubes were fabricated by using vacuum-assisted wetting and filtration of silica gel through a microchannel glass matrix. The microfibres and microtubes were studied using Scanning Electron Microscopy (SEM), micro-photoluminescence spectroscopy and fluorescence lifetime imaging confocal microscopy. In the emission spectra of the micro-resonators we find very narrow periodic peaks corresponding to the whispering gallery modes of two orthogonal polarizations with quality factors up to 3200. A strong enhancement in photoluminescence decay rates at high excitation power demonstrates the occurrence of amplified spontaneous emission from a single microtube. These microtubes show a large evanescent field extending many microns beyond the tube radius. Potential applications for these novel microresonators will be in the area of optical microsensors for a single molecule detection of biological and chemical species, including anti-terrorism and defense sectors.

  15. Shearfree cylindrical gravitational collapse

    SciTech Connect

    Di Prisco, A.; Herrera, L.; MacCallum, M. A. H.; Santos, N. O.

    2009-09-15

    We consider diagonal cylindrically symmetric metrics, with an interior representing a general nonrotating fluid with anisotropic pressures. An exterior vacuum Einstein-Rosen spacetime is matched to this using Darmois matching conditions. We show that the matching conditions can be explicitly solved for the boundary values of metric components and their derivatives, either for the interior or exterior. Specializing to shearfree interiors, a static exterior can only be matched to a static interior, and the evolution in the nonstatic case is found to be given in general by an elliptic function of time. For a collapsing shearfree isotropic fluid, only a Robertson-Walker dust interior is possible, and we show that all such cases were included in Cocke's discussion. For these metrics, Nolan and Nolan have shown that the matching breaks down before collapse is complete, and Tod and Mena have shown that the spacetime is not asymptotically flat in the sense of Berger, Chrusciel, and Moncrief. The issues about energy that then arise are revisited, and it is shown that the exterior is not in an intrinsic gravitational or superenergy radiative state at the boundary.

  16. Evaluation of ball and roller bearings restored by grinding

    NASA Technical Reports Server (NTRS)

    Parker, R. J.; Zaretsky, E. V.; Chen, S. M.

    1976-01-01

    The restoration by grinding of those rolling element bearings which are currently being discarded at aircaft engine and transmission overhaul is considered. Three bearing types were selected from the UH-1 helicopter engine and transmission for the pilot program. Groups of each of these bearings were visually and dimensionally inspected for suitability for restoration. A total of 250 bearings were restored by grinding. Of this number, 30 bearings from each type were endurance tested to a TBO of 1600 hours. No bearing failures occurred related to the restoration by grinding process. The two bearing failures which occurred were due to defective rolling elements and were typical of those which may occur in new bearings. The restorable component yield to the three groups was in excess of 90 percent.

  17. Evaluation of ball and roller bearings restored by grinding

    NASA Technical Reports Server (NTRS)

    Parker, R. J.; Zaretsky, E. V.; Chen, S. M.

    1976-01-01

    A joint program was undertaken to restore by grinding those rolling-element bearings which are currently being discarded at aircraft engine and transmission overhaul. Three bearing types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. Groups of each of these bearings were visually and dimensionally inspected for suitability for restoration. A total of 250 bearings were restored by grinding. Of this number, 30 bearings from each type were endurance tested to a TBO of 1600 hours. No bearing failures occurred related to the restoration by grinding process. The two bearing failures which occurred were due to defective rolling elements and were typical of those which may occur in new bearings. The restorable component yield to the three groups was in excess of 90 percent.

  18. Surface tension and long range corrections of cylindrical interfaces

    SciTech Connect

    Bourasseau, E.; Ghoufi, A.

    2015-12-21

    The calculation of the surface tension of curved interfaces has been deeply investigated from molecular simulation during this last past decade. Recently, the thermodynamic Test-Area (TA) approach has been extended to the calculation of surface tension of curved interfaces. In the case of the cylindrical vapour-liquid interfaces of water and Lennard-Jones fluids, it was shown that the surface tension was independent of the curvature of the interface. In addition, the surface tension of the cylindrical interface is higher than that of the planar interface. Molecular simulations of cylindrical interfaces have been so far performed (i) by using a shifted potential, (ii) by means of large cutoff without periodic boundary conditions, or (iii) by ignoring the long range corrections to the surface tension due to the difficulty to estimate them. Indeed, unlike the planar interfaces there are no available operational expressions to consider the tail corrections to the surface tension of cylindrical interfaces. We propose here to develop the long range corrections of the surface tension for cylindrical interfaces by using the non-exponential TA (TA2) method. We also extend the formulation of the Mecke-Winkelmann corrections initially developed for planar surfaces to cylindrical interfaces. We complete this study by the calculation of the surface tension of cylindrical surfaces of liquid tin and copper using the embedded atom model potentials.

  19. Cylindrical Projection of Jupiter

    NASA Technical Reports Server (NTRS)

    1979-01-01

    This computer generated map of Jupiter was made from 10 color images of Jupiter taken Feb. 1, 1979, by Voyager 1, during a single, 10 hour rotation of the planet. Computers at Jet Propulsion Laboratory's Image Processing Lab then turned the photos into this cylindrical projection. Such a projection is invaluable as an instantaneous view of the entire planet. Along the northern edge of the north equatorial belt (NEB) are four dark brown, oblong regions believed by some scientists to be openings in the more colorful upper cloud decks, allowing the darker clouds beneath to be seen. The broad equatorial zone (EZ) is dominated by a series of plumes, possibly regions of intense convective activity, encircling the entire planet. In the southern hemisphere the Great Red Spot is located at about 75 degrees longitude. South of the Great Red Spot in the south temperate zone (STeZ) three large white ovals, seen from Earth-based observatories for the past few decades, are located at 5 degrees, 85 degrees and 170 degrees longitude. Resolution in this map is 375 miles (600 kilometers). Since Jupiter's atmospheric features drift around the planet, longitude is based on the orientation of the planet's magnetic field. Symbols at right edge of photo denote major atmospheric features (dark belts and light zones): NTeZ - north temperate zone; NTrZ - north tropical zone; NEB - north equatorial belt; EZ - equatorial zone; SEB - south equatorial belt; STrZ - south tropical zone; and STeZ - south temperate zone. Voyager belt; EZ - equatorial zone; SEB - south tropical zone; Voyager is managed for NASA's Office of Space Science by Jet Propulsion Laboratory.

  20. Grinding methods to enhance the reactivity of olivine

    SciTech Connect

    Summers, Cathy A.; Dahlin, David C.; Rush, Gilbert E.; O'Connor, William K.; Gerdemann, Stephen J.

    2004-01-01

    The Albany Research Center (ARC) conducted studies of mechanical activation by conventional and ultra-fine grinding techniques to enhance olivine reactivity in mineral carbonation reactions. Activated olivine is one of several solid feed materials used at ARC in reactions with carbon dioxide to form carbonate minerals. This paper compares grinding techniques via energy demand data and product characteristics, including particle size distributions, surface areas, full width at half maximum (FWHM) XRD analyses, and particle morphology by SEM analyses. Reactivity was gauged by percent conversion to carbonate in subsequent carbonation tests.

  1. Energy efficiency of cement finish grinding in a dry batch ball mill

    SciTech Connect

    Touil, D.; Belaadi, S.; Frances, C. . E-mail: Christine.Frances@ensiacet.fr

    2006-03-15

    Dry grinding experiments on cement clinker were carried out using a laboratory batch ball mill equipped with torque measurement. The specific energy was found to be dependent on operating parameters and clinker environment. Additional compounds such as gypsum and pozzolanic tuff improve energy efficiency. The optimal parameters allowing maximising the energy efficiency factor were determined. Energy efficiency factors were obtained both on the crude material (size minus 2.8 mm) and on a sieved fraction (1-0.71 mm). They demonstrate that a low initial rate of breakage implies higher energy efficiency. On the contrary, conditions ensuring an initial maximal rate of breakage lead to an increase of the energy consumption.

  2. Effect of SAR on human head modeling inside cylindrical enclosures.

    PubMed

    Mary, T Anita Jones; Ravichandran, C S

    2013-09-01

    This study intends to discuss enclosed a realistic approach to determine and analyze the effects of radio frequency on human exposure inside a cylindrical enclosure. A scenario in which a mobile phone with inverted-F antenna (IFA) operating in the Global System for Mobile Communication (GSM) band (900 MHz) is used inside a cylindrical enclosure. Metallic enclosures are known to have resonance and reflection effects, thereby increasing electric field strength and hence resulting in a change of the human exposure to electromagnetic absorptions. So, this study examines and compares the levels of absorption in terms of specific absorption rate (SAR) values under various conditions. In this study, a human phantom with dielectric properties is designed and its interaction is studied with IFA inside fully enclosed cylindrical enclosures. The results show that SAR values are increased inside cylindrical enclosures compared with those in free space. The method of computation uses method of moments. Simulations are done in FEKO software. PMID:23323517

  3. Pulsed Laser Profiling of Grinding Wheels at Normal and Quasi-Tangential Incidence

    NASA Astrophysics Data System (ADS)

    Lutey, Adrian H. A.; Fortunato, Alessandro; Zanini, Filippo; Carmignato, Simone

    2016-09-01

    A new methodology for normal and quasi-tangential pulsed laser profiling of grinding wheels is proposed, with laser path planning calculated according to a pre-specified angle of incidence and radial laser progression or predicted single-pass incision depth. Though tangential laser profiling has previously been investigated, few works have addressed the issue of negligible laser absorption under these conditions other than to apply a focal offset that effectively reduces the angle of incidence below 90∘. In the present work, the angle of incidence is specified explicitly, with normal and quasi-tangential profiling experiments performed on rotating bronze-bonded diamond and porous aluminum oxide grinding wheels with a 1064 nm nanosecond pulsed fiber laser source with 20 W average power. Triangular incisions are cut into each sample, following which analyses are performed with an optical profiler operating in confocal mode and x-ray computed tomography to determine the material removal rate and profile accuracy under all tested conditions. The angle of laser incidence is found to be of particular relevance to profiling operations, with more than one order of magnitude difference in material removal rates observed between 70∘ and 80∘ incidence, with improved profile accuracy in the latter case. Specifically, material removal rates of 0.12-0.14 mm 3/ s, 0.075-0.1 mm 3/ s and 0.002 mm 3/ s are achieved at normal, 70∘ and 80∘ laser incidence, respectively, for bronze-bonded diamond, and 0.1 mm 3/ s is achieved at 70∘ incidence for porous aluminum oxide. For both materials, profile accuracy of 50-70 μm is achieved under optimum conditions. The presented results highlight the necessity for precise specification and control of the angle of incidence during laser profiling operations. They furthermore confirm that laser profiling of grinding wheels is a viable alternative to electrical discharge machining for bronze-bonded diamond grinding wheels and a potential

  4. Pulsed Laser Profiling of Grinding Wheels at Normal and Quasi-Tangential Incidence

    NASA Astrophysics Data System (ADS)

    Lutey, Adrian H. A.; Fortunato, Alessandro; Zanini, Filippo; Carmignato, Simone

    2016-06-01

    A new methodology for normal and quasi-tangential pulsed laser profiling of grinding wheels is proposed, with laser path planning calculated according to a pre-specified angle of incidence and radial laser progression or predicted single-pass incision depth. Though tangential laser profiling has previously been investigated, few works have addressed the issue of negligible laser absorption under these conditions other than to apply a focal offset that effectively reduces the angle of incidence below 90∘. In the present work, the angle of incidence is specified explicitly, with normal and quasi-tangential profiling experiments performed on rotating bronze-bonded diamond and porous aluminum oxide grinding wheels with a 1064 nm nanosecond pulsed fiber laser source with 20 W average power. Triangular incisions are cut into each sample, following which analyses are performed with an optical profiler operating in confocal mode and x-ray computed tomography to determine the material removal rate and profile accuracy under all tested conditions. The angle of laser incidence is found to be of particular relevance to profiling operations, with more than one order of magnitude difference in material removal rates observed between 70∘ and 80∘ incidence, with improved profile accuracy in the latter case. Specifically, material removal rates of 0.12-0.14 mm 3/s, 0.075-0.1 mm 3/s and 0.002 mm 3/s are achieved at normal, 70∘ and 80∘ laser incidence, respectively, for bronze-bonded diamond, and 0.1 mm 3/s is achieved at 70∘ incidence for porous aluminum oxide. For both materials, profile accuracy of 50-70 μm is achieved under optimum conditions. The presented results highlight the necessity for precise specification and control of the angle of incidence during laser profiling operations. They furthermore confirm that laser profiling of grinding wheels is a viable alternative to electrical discharge machining for bronze-bonded diamond grinding wheels and a potential

  5. Recovery of titanium values from titanium grinding swarf by electric furnace smelting

    DOEpatents

    Gerdemann, S.J.; White, J.C.

    1998-08-04

    A method for the recovery of valuable materials from titanium grinding swarf is provided comprising the steps of sieving the accumulated titanium grinding swarf to remove unwanted coarse trash and grinding wheel fragments, pelletizing, and smelting in an electric arc furnace to produce ferrotitanium and/or high titanium slag. 1 fig.

  6. Recovery of titanium values from titanium grinding swarf by electric furnace smelting

    DOEpatents

    Gerdemann, Stephen J.; White, Jack C.

    1999-01-01

    A method for the recovery of valuable materials from titanium grinding swarf is provided comprising the steps of sieving the accumulated titanium grinding swarf to remove unwanted coarse trash and grinding wheel fragments, pelletizing, and smelting in an electric arc furnace to produce ferrotitanium and/or high titanium slag.

  7. Recovery of titanium values from titanium grinding swarf by electric furnace smelting

    DOEpatents

    Gerdemann, Stephen J.; White, Jack C.

    1998-01-01

    A method for the recovery of valuable materials from titanium grinding swarf is provided comprising the steps of sieving the accumulated titanium grinding swarf to remove unwanted coarse trash and grinding wheel fragments, pelletizing, and smelting in an electric arc furnace to produce ferrotitanium and/or high titanium slag.

  8. Grinding Kinetics of Vanadium-Titanium Magnetite Concentrate in a Damp Mill and Its Properties

    NASA Astrophysics Data System (ADS)

    Long, Hongming; Chun, Tiejun; Wang, Ping; Meng, Qingmin; Di, Zhanxia; Li, Jiaxin

    2016-06-01

    The grinding behavior of the as-received (5 pct moisture) vanadium-titanium magnetite concentrates in a damp mill was investigated in this paper. A grinding kinetics equation was established based on a population balance model using size distribution data obtained from a laser diffraction technique. X-ray diffraction results show that a loss in crystallinity occurs when the grinding time is increased. The crystallite size of the materials decreased, whereas their structural microstrain increased with increasing grinding time. The wettability increased because the surface roughness increases with increasing grinding time. The moisture capacity of the solids increased during the first 3 minutes of grinding and then remained roughly constant with further increases in grinding time. The water transfer coefficient of the particles increased at grinding times of 3 and 6 minutes and then decreased at grinding times of 9 and 12 minutes. The compressive strength of oxidized pellets increased with increasing grinding time; longer grinding times can compensate for the effects of lower roasting temperature or shorter roasting time on the strength of the pellets. Lowering the roasting temperature and shortening the roasting time by grinding appeared to be possible.

  9. Recovery of titanium values from titanium grinding swarf by electric furnace smelting

    SciTech Connect

    Gerdemann, S.J.; White, J.C.

    1999-10-19

    A method for the recovery of valuable materials from titanium grinding swarf is provided comprising the steps of sieving the accumulated titanium grinding swarf to remove unwanted coarse trash and grinding wheel fragments, pelletizing, and smelting in an electric arc furnace to produce ferrotitanium and/or high titanium slag.

  10. 30 CFR 77.401 - Stationary grinding machines; protective devices.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... devices. 77.401 Section 77.401 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF...; protective devices. (a) Stationary grinding machines other than special bit grinders shall be equipped with: (1) Peripheral hoods (less than 90° throat openings) capable of withstanding the force of a...

  11. 30 CFR 77.401 - Stationary grinding machines; protective devices.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... devices. 77.401 Section 77.401 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF...; protective devices. (a) Stationary grinding machines other than special bit grinders shall be equipped with: (1) Peripheral hoods (less than 90° throat openings) capable of withstanding the force of a...

  12. INTERIOR VIEW WITH GRINDING MILL AND CONVEYOR EXTENDING UP TO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW WITH GRINDING MILL AND CONVEYOR EXTENDING UP TO SORTING DRUM. DRIVE ENGINE AT LOWER LEFT. RADIATOR FOR ENGINE AT RIGHT. - F. & H. Benning Company Oyster Mill, 14430 Solomons Island Road (moved from 1014 Benning Road, Galesville, Anne Arundel County, Maryland), Solomons, Calvert County, MD

  13. VIEW, LOOKING WEST TOWARD GRINDING AREA, OF MAINTENCE SHOP. NOTE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW, LOOKING WEST TOWARD GRINDING AREA, OF MAINTENCE SHOP. NOTE TRACK IN FLOOR FOR CARTS WITH HEAVY ITEMS, OVERHEAD JIB CRANE AT UPPER RIGHT, PARTIALLY OBSCURED "SG" LOGO ON CABINET, AND SIGNS ABOVE DOORWAY TO MILL. - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO

  14. GRINDING ROOM, LOOKING EAST. NOTE OVERHEAD BRIDGE CRANE RIDING ON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    GRINDING ROOM, LOOKING EAST. NOTE OVERHEAD BRIDGE CRANE RIDING ON STEEL RAILS SUPPORTED BY WOODEN BEAMS AND CYCLONE CLASSIFIER IN CENTER. AT RIGHT IS TOP PORTION OF FLASH FLOTATION CELL. - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO

  15. Multisurface fixture permits easy grinding of tool bit angles

    NASA Technical Reports Server (NTRS)

    Jones, C. R.

    1966-01-01

    Multisurface fixture with a tool holder permits accurate grinding and finishing of right and left hand single point threading tools. All angles are ground by changing the fixture position to rest at various references angles without removing the tool from the holder.

  16. Computer numerical control grinding of spiral bevel gears

    NASA Technical Reports Server (NTRS)

    Scott, H. Wayne

    1991-01-01

    The development of Computer Numerical Control (CNC) spiral bevel gear grinding has paved the way for major improvement in the production of precision spiral bevel gears. The object of the program was to decrease the setup, maintenance of setup, and pattern development time by 50 percent of the time required on conventional spiral bevel gear grinders. Details of the process are explained.

  17. Enhanced Performance of Cylindrical Hall Thrusters

    SciTech Connect

    Y. Raitses, A. Smirnov, and N.J. Fisch

    2007-05-14

    The cylindrical thruster differs significantly in its underlying physical mechanisms from the conventional annular Hall thruster. It features high ionization efficiency, quiet operation, ion acceleration in a large volume-to-surface ratio channel, and performance comparable with the state-of-the-art conventional Hall thrusters. Very significant plume narrowing, accompanied by the increase of the energetic ion fraction and improvement of ion focusing, led to 50%–60% increase of the thruster anode efficiency. These improvements were achieved by overrunning the discharge current in the magnetized thruster plasma.

  18. Enhanced performance of cylindrical Hall thrusters

    SciTech Connect

    Raitses, Y.; Smirnov, A.; Fisch, N. J.

    2007-05-28

    The cylindrical thruster differs significantly in its underlying physical mechanisms from the conventional annular Hall thruster. It features high ionization efficiency, quiet operation, ion acceleration in a large volume-to-surface ratio channel, and performance comparable with the state-of-the-art conventional Hall thrusters. Very significant plume narrowing, accompanied by the increase of the energetic ion fraction and improvement of ion focusing, led to 50%-60% increase of the thruster anode efficiency. These improvements were achieved by overrunning the discharge current in the magnetized thruster plasma.

  19. Development of an intelligent grinding wheel for in-process monitoring of ceramic grinding. Semi-annual report {number_sign}3

    SciTech Connect

    Malkin, S.; Gao, R.; Guo, C.; Varghese, B.; Pathare, S.

    1998-03-26

    This is the third semi-annual report for the project. The overall objective of this project is to develop sensor-integrated intelligent diamond wheels for grinding of ceramics. Such wheels will be smart enough to monitor and supervise both the wheel preparation and grinding processes without the need to instrument the machine tool. Intelligent wheels will utilize re-useable cores integrated with sensors: to measure the acoustic emission (AE) and grinding force. Signals from the sensors will be transmitted from a rotating wheel to a receiver by telemetry. Wheels will be trained to recognize distinct characteristics associated with truing, dressing and grinding. The technical progress is summarized in this report.

  20. Subsurface mechanical damage during bound abrasive grinding of fused silica glass

    NASA Astrophysics Data System (ADS)

    Blaineau, P.; André, D.; Laheurte, R.; Darnis, P.; Darbois, N.; Cahuc, O.; Neauport, J.

    2015-10-01

    The subsurface damage (SSD) introduced during bound abrasive grinding of fused silica glass was measured using a wet etch technique. Various process parameters and grinding configurations were studied. The relation between the SSD depth, the process parameters and forces applied by the grinding wheel on the sample was investigated and compared to a simulation using a discrete element method to model the grinding interface. The results reveal a relation between the SSD depth and the grinding forces normalized by the abrasive concentration. Regarding the creation of the SSD, numerical simulations indicate that only a small fraction of the largest particles in the diamond wheel are responsible for the depth of the damaged layer.

  1. Cylindrical acoustic levitator/concentrator

    DOEpatents

    Kaduchak, Gregory; Sinha, Dipen N.

    2002-01-01

    A low-power, inexpensive acoustic apparatus for levitation and/or concentration of aerosols and small liquid/solid samples having particulates up to several millimeters in diameter in air or other fluids is described. It is constructed from a commercially available, hollow cylindrical piezoelectric crystal which has been modified to tune the resonance frequency of the breathing mode resonance of the crystal to that of the interior cavity of the cylinder. When the resonance frequency of the interior cylindrical cavity is matched to the breathing mode resonance of the cylindrical piezoelectric transducer, the acoustic efficiency for establishing a standing wave pattern in the cavity is high. The cylinder does not require accurate alignment of a resonant cavity. Water droplets having diameters greater than 1 mm have been levitated against the force of gravity using; less than 1 W of input electrical power. Concentration of aerosol particles in air is also demonstrated.

  2. Development of a grinding-specific performance test set-up.

    PubMed

    Olesen, C G; Larsen, B H; Andresen, E L; de Zee, M

    2015-01-01

    The aim of this study was to develop a performance test set-up for America's Cup grinders. The test set-up had to mimic the on-boat grinding activity and be capable of collecting data for analysis and evaluation of grinding performance. This study included a literature-based analysis of grinding demands and a test protocol developed to accommodate the necessary physiological loads. This study resulted in a test protocol consisting of 10 intervals of 20 revolutions each interspersed with active resting periods of 50 s. The 20 revolutions are a combination of both forward and backward grinding and an exponentially rising resistance. A custom-made grinding ergometer was developed with computer-controlled resistance and capable of collecting data during the test. The data collected can be used to find measures of grinding performance such as peak power, time to complete and the decline in repeated grinding performance. PMID:25367077

  3. Fatigue limit of polycrystalline zirconium oxide ceramics: Effect of grinding and low-temperature aging.

    PubMed

    Pereira, G K R; Silvestri, T; Amaral, M; Rippe, M P; Kleverlaan, C J; Valandro, L F

    2016-08-01

    The following study aimed to evaluate the effect of grinding and low-temperature aging on the fatigue limit of Y-TZP ceramics for frameworks and monolithic restorations. Disc specimens from each ceramic material, Lava Frame (3M ESPE) and Zirlux FC (Ivoclar Vivadent) were manufactured according to ISO:6872-2008 and assigned in accordance with two factors: (1) "surface treatment"-without treatment (as-sintered, Ctrl), grinding with coarse diamond bur (181µm; Grinding); and (2) "low-temperature aging (LTD)" - presence and absence. Grinding was performed using a contra-angle handpiece under constant water-cooling. LTD was simulated in an autoclave at 134°C under 2-bar pressure for 20h. Mean flexural fatigue limits (20,000 cycles) were determined under sinusoidal loading using stair case approach. For Lava ceramic, it was observed a statistical increase after grinding procedure and different behavior after LTD stimuli (Ctrl<Grinding; CtrlGrinding=Grinding Ltd); while for Zirlux, grinding and low-temperature aging promoted a statistical increase in the fatigue limit (Ctrl<Grinding; CtrlGrinding Ltd). An important increase was observed in m-phase content after both stimuli (grinding and LTD), although with different intensities. Additionally, fatigue test did not promote increase of m-phase content. Thus, tested grinding and low temperature aging did not damage the fatigue limit values significantly for both materials evaluated, even though those conditions promoted increase in m-phase. PMID:26828768

  4. Telescoping cylindrical piezoelectric fiber composite actuator assemblies

    NASA Technical Reports Server (NTRS)

    Allison, Sidney G. (Inventor); Shams, Qamar A. (Inventor); Fox, Robert L. (Inventor); Fox, legal representative, Christopher L. (Inventor); Fox Chattin, legal representative, Melanie L. (Inventor)

    2010-01-01

    A telescoping actuator assembly includes a plurality of cylindrical actuators in a concentric arrangement. Each cylindrical actuator is at least one piezoelectric fiber composite actuator having a plurality of piezoelectric fibers extending parallel to one another and to the concentric arrangement's longitudinal axis. Each cylindrical actuator is coupled to concentrically-adjacent ones of the cylindrical actuators such that the plurality of cylindrical actuators can experience telescopic movement. An electrical energy source coupled to the cylindrical actuators applies actuation energy thereto to generate the telescopic movement.

  5. JKR adhesion in cylindrical contacts

    NASA Astrophysics Data System (ADS)

    Sundaram, Narayan; Farris, T. N.; Chandrasekar, S.

    2012-01-01

    Planar JKR adhesive solutions use the half-plane assumption and do not permit calculation of indenter approach or visualization of adhesive force-displacement curves unless the contact is periodic. By considering a conforming cylindrical contact and using an arc crack analogy, we obtain closed-form indenter approach and load-contact size relations for a planar adhesive problem. The contact pressure distribution is also obtained in closed-form. The solutions reduce to known cases in both the adhesion-free and small-contact solution ( Barquins, 1988) limits. The cylindrical system shows two distinct regimes of adhesive behavior; in particular, contact sizes exceeding the critical (maximum) size seen in adhesionless contacts are possible. The effects of contact confinement on adhesive behavior are investigated. Some special cases are considered, including contact with an initial neat-fit and the detachment of a rubbery cylinder from a rigid cradle. A comparison of the cylindrical solution with the half-plane adhesive solution is carried out, and it indicates that the latter typically underestimates the adherence force. The cylindrical adhesive system is novel in that it possesses stable contact states that may not be attained even on applying an infinite load in the absence of adhesion.

  6. Optics Demonstrations Using Cylindrical Lenses

    ERIC Educational Resources Information Center

    Ivanov, Dragia; Nikolov, Stefan

    2015-01-01

    In this paper we consider the main properties of cylindrical lenses and propose several demonstrational experiments that can be performed with them. Specifically we use simple glasses full of water to demonstrate some basic geometrical optics principles and phenomena. We also present some less standard experiments that can be performed with such…

  7. Vibration of perforated cylindrical shells

    NASA Astrophysics Data System (ADS)

    Cousseau, Peter L.

    For a credible design of an inertial confinement fusion (ICF) target chamber, the vibration characteristics of the chamber must be completely understood. Target chambers are usually cylindrical or spherical in shape and contain hundreds of perforations (called ports) to allow access to the inside of the chamber. The fusion reaction within the chamber creates a uniform impulsive loading, which the chamber walls must be designed to contain. Also prior to an implosion, a delicate alignment process of the drivers and diagnostics takes place. The vibration of the chamber from rotating machinery, e.g., vacuum pumps, and ambient sources must be completely understood and accounted for during these alignment procedures. This dissertation examines the vibration characteristics of perforated cylindrical shells. Because the target chambers' thickness-to-radius ratio is small, such chambers can be modeled as thin shells. Included in the text is a literature review of perforated plates and shells and examples of the use of perforated structures in constructed and proposed ICF target chambers. The natural frequencies and corresponding mode shapes of perforated and unperforated cylindrical shells are studied analytically, numerically (via finite elements) and experimentally. Conclusions and comparisons between the different solution methods are made for both the perforated and unperforated cases. In addition, the dynamic response of perforated cylindrical shells to an axisymmetric impulsive loading has been identified. A demonstration showing how the convolution integral can be used to determine the response of a cylinder to a non-impulsive loading is presented.

  8. New Geometry of Worm Face Gear Drives with Conical and Cylindrical Worms: Generation, Simulation of Meshing, and Stress Analysis

    NASA Technical Reports Server (NTRS)

    Litvin, Faydor L.; Nava, Alessandro; Fan, Qi; Fuentes, Alfonso

    2002-01-01

    New geometry of face worm gear drives with conical and cylindrical worms is proposed. The generation of the face worm-gear is based on application of a tilted head-cutter (grinding tool) instead of application of a hob applied at present. The generation of a conjugated worm is based on application of a tilted head-cutter (grinding tool) as well. The bearing contact of the gear drive is localized and is oriented longitudinally. A predesigned parabolic function of transmission errors for reduction of noise and vibration is provided. The stress analysis of the gear drive is performed using a three-dimensional finite element analysis. The contacting model is automatically generated. The developed theory is illustrated with numerical examples.

  9. Teeth Grinding: Is Emotional Stability related to Bruxism?

    PubMed

    Sutin, Angelina R; Terracciano, Antonio; Ferrucci, Luigi; Costa, Paul T

    2010-06-01

    This study examines the association between personality traits and bruxism, the repetitive grinding or clenching of teeth. Community-dwelling participants (N = 470) had a comprehensive oral examination by a dentist and completed a dental history and personality questionnaires. Consistent with the literature on state anxiety and depression as antecedents of bruxism, Neuroticism-related traits were associated with self-reported teeth grinding. These traits were also associated with other oral complaints often associated with anxiety (jaw clicks, difficulty chewing food, and dry mouth), but not with more general oral health complaints (unhealthy gums, bleeding gums, and canker sores) or with dentist-assessed occlusal wear or tongue indentations. This study provides evidence for the association between Neuroticism and bruxism and other stress-related oral health symptoms. PMID:20835403

  10. Spirit's First Grinding of a Rock on Mars

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The round, shallow depression in this image resulted from history's first grinding of a rock on Mars. The rock abrasion tool on NASA's Spirit rover ground off the surface of a patch 45.5 millimeters (1.8 inches) in diameter on a rock called Adirondack. The hole is 2.65 millimeters (0.1 inch) deep, exposing fresh interior material of the rock for close inspection with the rover's microscopic imager and two spectrometers on the robotic arm. This image was taken by Spirit's panoramic camera, providing a quick visual check of the success of the grinding. The rock abrasion tools on both Mars Exploration Rovers were supplied by Honeybee Robotics, New York, N.Y.

  11. Process for selective grinding of coal

    DOEpatents

    Venkatachari, Mukund K.; Benz, August D.; Huettenhain, Horst

    1991-01-01

    A process for preparing coal for use as a fuel. Forming a coal-water slurry having solid coal particles with a particle size not exceeding about 80 microns, transferring the coal-water slurry to a solid bowl centrifuge, and operating same to classify the ground coal-water slurry to provide a centrate containing solid particles with a particle size distribution of from about 5 microns to about 20 microns and a centrifuge cake of solids having a particle size distribution of from about 10 microns to about 80 microns. The classifer cake is reground and mixed with fresh feed to the solid bowl centrifuge for additional classification.

  12. 12. INTERIOR VIEW, FIRST FLOOR SHOWING GRINDING STONES COVERED WITH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. INTERIOR VIEW, FIRST FLOOR SHOWING GRINDING STONES COVERED WITH VATS (RIGHT STONE RUN BY 35' LEFFAL VERTICAL TURBINE; LEFT BY 23' 1EFFAL VERTICAL TURBINE). THE HOPPER ON THE VAT TO THE LEFT FUNNELS THE GRAIN IN. THE CHUTE AT THE BOTTOM OF THE CENTER VAT SENDS GROUND GRAIN TO THE CONVEYOR BELOW. - Schech's Mill, Beaver Creek State Park, La Crescent, Houston County, MN

  13. Grinding Induced Changes in Residual Stresses of Carburized Gears

    SciTech Connect

    Lemaster, Robert A; Boggs, Bryan L; Bunn, Jeffrey R; Hubbard, Camden R; Watkins, Thomas R

    2009-01-01

    This paper presents the results of a study performed to measure the change in residual stress that results from the finish grinding of carburized gears. Residual stresses were measured in five gears using the x-ray diffraction equipment in the Large Specimen Residual Stress Facility at Oak Ridge National Laboratory. Two of the gears were hobbed, carburized, quenched and tempered, but not finished. The remaining three gears were processed similarly, but were finish ground. The residual stresses were measured at 64 different locations on a tooth from each gear. Residual stresses were also measured at fewer points on other teeth to determine the tooth-to-tooth variation. Tooth profile measurements were made of the finished and unfinished gear samples. The results show a fairly uniform and constant compressive residual field in the nonfinished gears. There was a significant reduction in the average residual stress measured in the finished gears. Additionally, there was a significant increase in the variability of the residual stress that was introduced by the grinding process. Analysis of the data suggests a linear relationship between the change in average residual stress and the amount of material removed by the grinding process.

  14. Cooking and grinding reduces the cost of meat digestion.

    PubMed

    Boback, Scott M; Cox, Christian L; Ott, Brian D; Carmody, Rachel; Wrangham, Richard W; Secor, Stephen M

    2007-11-01

    The cooking of food is hypothesized to have played a major role in human evolution partly by providing an increase in net energy gain. For meat, cooking compromises the structural integrity of the tissue by gelatinizing the collagen. Hence, cooked meat should take less effort to digest compared to raw meat. Likewise, less energy would be expended digesting ground meat compared to intact meat. We tested these hypotheses by assessing how the cooking and/or grinding of meat influences the energy expended on its digestion, absorption, and assimilation (i.e., specific dynamic action, SDA) using the Burmese python, Python molurus. Pythons were fed one of four experimental diets each weighing 25% of the snake's body mass: intact raw beef, intact cooked beef, ground raw beef, and ground cooked beef. We measured oxygen consumption rates of snakes prior to and up to 14 days following feeding and calculated SDA from the extra oxygen consumed above standard metabolic rate. Postprandial peak in oxygen consumption, the scope of peak rates, and SDA varied significantly among meal treatments. Pythons digesting raw or intact meals exhibited significantly larger postprandial metabolic responses than snakes digesting the cooked ground meals. We found cooking to decrease SDA by 12.7%, grinding to decrease SDA by 12.4%, and the combination of the two (cooking and grinding) to have an additive effect, decreasing SDA by 23.4%. These results support the hypothesis that the consumption of cooked meat provides an energetic benefit over the consumption of raw meat. PMID:17827047

  15. Rotary ultrasonic machining of CFRP: A comparison with grinding.

    PubMed

    Ning, F D; Cong, W L; Pei, Z J; Treadwell, C

    2016-03-01

    Carbon fiber reinforced plastic (CFRP) composites have been intensively used in various industries due to their superior properties. In aircraft and aerospace industry, a large number of holes are required to be drilled into CFRP components at final stage for aircraft assembling. There are two major types of methods for hole making of CFRP composites in industry, twist drilling and its derived multi-points machining methods, and grinding and its related methods. The first type of methods are commonly used in hole making of CFRP composites. However, in recent years, rotary ultrasonic machining (RUM), a hybrid machining process combining ultrasonic machining and grinding, has also been successfully used in drilling of CFRP composites. It has been shown that RUM is superior to twist drilling in many aspects. However, there are no reported investigations on comparisons between RUM and grinding in drilling of CFRP. In this paper, these two drilling methods are compared in five aspects, including cutting force, torque, surface roughness, hole diameter, and material removal rate. PMID:26614168

  16. The Effect of Moisture Content on Determining Corn Hardness from Grinding Time and Grinding Energy, and Hardness Prediction Using Near-Infrared Spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Stenvert hardness test was used to determine the energy-to-grind (ETG) and time-to-grind (TTG) of 107 food-grade corn hybrids at different moisture content (MC) levels. ETG and TTG were significantly affected by moisture content. Across hybrids, ETG displayed the most consistent response to MC...

  17. Effects of Compressive Force, Particle Size and Moisture Content on Mechanical Properties of Biomass Grinds

    SciTech Connect

    Mani, Sudhagar; Tabil, Lope Jr.; Sokhansanj, Shahabaddine

    2006-03-01

    Chemical composition, moisture content, bulk and particle densities, and geometric mean particle size were determined to characterize grinds from wheat and barley straws, corn stover and switchgrass. The biomass grinds were compressed for five levels of compressive forces (1000, 2000, 3000, 4000, 4400 N) and three levels of particle sizes (3.2, 1.6 and 0.8 mm) at two levels of moisture contents (12% and 15% (wb) to establish the compression and relaxation data. Corn stover grind produced the highest compact density at low pressure during compression. Compressive force, particle size and moisture content of grinds significantly affected the compact density of barley straw, corn stover and switchgrass grinds. However, different particle sizes of wheat straw grind did not produce any significant difference on compact density. Barley straw grind had the highest asymptotic modulus among all other biomass grinds indicating that compact from barley straw grind were more rigid than those of other compacts. Asymptotic modulus increased with an increase in maximum compressive pressure. The trend of increase in asymptotic modulus (EA) with the maximum compressive pressure ( 0) was fitted to a second order polynomial equation. Keywords: Biomass grinds, chemical composition, compact density and asymptotic modulus

  18. A study of cylindrical Hall thruster for low power space applications

    SciTech Connect

    Y. Raitses; N.J. Fisch; K.M. Ertmer; C.A. Burlingame

    2000-07-27

    A 9 cm cylindrical thruster with a ceramic channel exhibited performance comparable to the state-of-the-art Hall thrusters at low and moderate power levels. Significantly, its operation is not accompanied by large amplitude discharge low frequency oscillations. Preliminary experiments on a 2 cm cylindrical thruster suggest the possibility of a high performance micro Hall thruster.

  19. High Speed Cylindrical Roller Bearing Analysis, SKF Computer Program CYBEAN. Volume 1: Analysis

    NASA Technical Reports Server (NTRS)

    Kleckner, R. J.; Pirvics, J.

    1978-01-01

    The CYBEAN (CYlindrical BEaring ANalysis) program was created to detail radially loaded, aligned and misaligned Cylindrical roller bearing performance under a variety of operating conditions. The models and associated mathematics used within CYBEAN are described. The user is referred to the material for formulation assumptions and algorithm detail.

  20. Calibrated cylindrical Mach probe in a plasma wind tunnel

    SciTech Connect

    Zhang, X.; Dandurand, D.; Gray, T.; Brown, M. R.; Lukin, V. S.

    2011-03-15

    A simple cylindrical Mach probe is described along with an independent calibration procedure in a magnetized plasma wind tunnel. A particle orbit calculation corroborates our model. The probe operates in the weakly magnetized regime in which probe dimension and ion orbit are of the same scale. Analytical and simulation models are favorably compared with experimental calibration.

  1. Parametric Investigations of Miniaturized Cylindrical and Annular Hall Thrusters

    SciTech Connect

    A. Smirnov; Y. Raitses; N.J. Fisch

    2001-10-16

    A cylindrical geometry Hall thruster may overcome certain physical and technological limitations in scaling down of Hall thrusters to miniature sizes. The absence of the inner wall and use of the cusp magnetic field can potentially reduce heating of the thruster parts and erosion of the channel. A 2.6 cm miniaturized Hall thruster of a flexible design was built and successfully operated in the power range of 50-300 W. Comparison of preliminary results obtained for cylindrical and annular thruster configurations is presented.

  2. Cylindrical magnets and ideal solenoids

    NASA Astrophysics Data System (ADS)

    Derby, Norman; Olbert, Stanislaw

    2010-03-01

    Both wire-wound solenoids and cylindrical magnets can be approximated as ideal azimuthally symmetric solenoids. We present an exact solution for the magnetic field of an ideal solenoid in an easy to use form. The field is expressed in terms of a single function that can be rapidly computed by means of a compact efficient algorithm, which can be coded as an add-in function to a spreadsheet, making field calculations accessible to introductory students. These expressions are not only accurate but are also as fast as most approximate expressions. We demonstrate their utility by simulating the dropping of a cylindrical magnet through a nonmagnetic conducting tube and comparing the calculation with data obtained from experiments suitable for an undergraduate laboratory.

  3. Thermal stress in high temperature cylindrical fasteners

    NASA Technical Reports Server (NTRS)

    Blosser, Max L.

    1988-01-01

    Uninsulated structures fabricated from carbon or silicon-based materials, which are allowed to become hot during flight, are attractive for the design of some components of hypersonic vehicles. They have the potential to reduce weight and increase vehicle efficiency. Because of manufacturing contraints, these structures will consist of parts which must be fastened together. The thermal expansion mismatch between conventional metal fasteners and carbon or silicon-based structural materials may make it difficult to design a structural joint which is tight over the operational temperature range without exceeding allowable stress limits. In this study, algebraic, closed-form solutions for calculating the thermal stresses resulting from radial thermal expansion mismatch around a cylindrical fastener are developed. These solutions permit a designer to quickly evaluate many combinations of materials for the fastener and the structure. Using the algebraic equations developed, material properties and joint geometry were varied to determine their effect on thermal stresses. Finite element analyses were used to verify that the closed-form solutions derived give the correct thermal stress distribution around a cylindrical fastener and to investigate the effect of some of the simplifying assumptions made in developing the closed-form solutions for thermal stresses.

  4. Design parameters for rotating cylindrical filtration

    NASA Technical Reports Server (NTRS)

    Schwille, John A.; Mitra, Deepanjan; Lueptow, Richard M.

    2002-01-01

    Rotating cylindrical filtration displays significantly reduced plugging of filter pores and build-up of a cake layer, but the number and range of parameters that can be adjusted complicates the design of these devices. Twelve individual parameters were investigated experimentally by measuring the build-up of particles on the rotating cylindrical filter after a fixed time of operation. The build-up of particles on the filter depends on the rotational speed, the radial filtrate flow, the particle size and the gap width. Other parameters, such as suspension concentration and total flow rate are less important. Of the four mechanisms present in rotating filters to reduce pore plugging and cake build-up, axial shear, rotational shear, centrifugal sedimentation and vortical motion, the evidence suggests rotational shear is the dominant mechanism, although the other mechanisms still play minor roles. The ratio of the shear force acting parallel to the filter surface on a particle to the Stokes drag acting normal to the filter surface on the particle due to the difference between particle motion and filtrate flow can be used as a non-dimensional parameter that predicts the degree of particle build-up on the filter surface for a wide variety of filtration conditions. c2002 Elsevier Science B.V. All rights reserved.

  5. GRIPPING DEVICE FOR CYLINDRICAL OBJECTS

    DOEpatents

    Pilger, J.P.

    1964-01-21

    A gripping device is designed for fragile cylindrical objects such as for drawing thin-walled tubes. The gripping is done by multiple jaw members held in position by two sets of slots, one defined by keystone-shaped extensions of the outer shell of the device and the other in a movable sleeve held slidably by the extensions. Forward movement oi the sleeve advances the jaws, thereby exerting a controlled, radial pressure on the object being gripped. (AEC)

  6. Dynamics of tilted cylindrical geometry

    NASA Astrophysics Data System (ADS)

    Sharif, M.; Sadiq, Sobia

    2016-09-01

    In this paper, we study the dynamics of tilted cylindrical model with imperfect matter distribution. We formulate the field equations and develop relations between tilted and non-tilted variables. We evaluate kinematical as well as dynamical quantities and discuss the inhomogeneity factor. We also obtain the Raychaudhuri equation to study evolution of expansion scalar. The solutions of field equations are also investigated for static cylinder under isotropy and conformally flat condition. Finally, we analyze some thermoinertial aspects of the system.

  7. Cylindrical solutions in mimetic gravity

    NASA Astrophysics Data System (ADS)

    Momeni, Davood; Myrzakulov, Kairat; Myrzakulov, Ratbay; Raza, Muhammad

    2016-06-01

    This paper is devoted to investigate cylindrical solutions in mimetic gravity. The explicit forms of the metric of this theory, namely mimetic-Kasner (say) have been obtained. In this study we have noticed that the Kasner's family of exact solutions needs to be reconsidered under this type of modified gravity. A no-go theorem is proposed for the exact solutions in the presence of a cosmological constant.

  8. Cylindrical solutions in braneworld gravity

    SciTech Connect

    Khoeini-Moghaddam, S.; Nouri-Zonoz, M.

    2005-09-15

    In this article we investigate exact cylindrically symmetric solutions to the modified Einstein field equations in the braneworld gravity scenarios. It is shown that for the special choice of the equation of state 2U+P=0 for the dark energy and dark pressure, the solutions found could be considered formally as solutions of the Einstein-Maxwell equations in 4-D general relativity.

  9. Cylindrical Piezoelectric Fiber Composite Actuators

    NASA Technical Reports Server (NTRS)

    Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.

    2008-01-01

    The use of piezoelectric devices has become widespread since Pierre and Jacques Curie discovered the piezoelectric effect in 1880. Examples of current applications of piezoelectric devices include ultrasonic transducers, micro-positioning devices, buzzers, strain sensors, and clocks. The invention of such lightweight, relatively inexpensive piezoceramic-fiber-composite actuators as macro fiber composite (MFC) actuators has made it possible to obtain strains and displacements greater than those that could be generated by prior actuators based on monolithic piezoceramic sheet materials. MFC actuators are flat, flexible actuators designed for bonding to structures to apply or detect strains. Bonding multiple layers of MFC actuators together could increase force capability, but not strain or displacement capability. Cylindrical piezoelectric fiber composite (CPFC) actuators have been invented as alternatives to MFC actuators for applications in which greater forces and/or strains or displacements may be required. In essence, a CPFC actuator is an MFC or other piezoceramic fiber composite actuator fabricated in a cylindrical instead of its conventional flat shape. Cylindrical is used here in the general sense, encompassing shapes that can have circular, elliptical, rectangular or other cross-sectional shapes in the planes perpendicular to their longitudinal axes.

  10. Strength and power determinants of grinding performance in America's Cup sailors.

    PubMed

    Pearson, Simon N; Hume, Patria A; Cronin, John B; Slyfield, David

    2009-09-01

    The purpose grinding is a physically demanding component of America's Cup sailing that is important to overall team performance, but little research is available on the determinants of grinding performance. We examined the relationship between various measures of muscular performance and the performance of upper-body grinding. Eleven elite male America's Cup sailors (33.9 +/- 5.5 yr, 97.8 +/- 12.5 kg, 186.0 +/- 7.1 cm) who performed grinding as part of their on-board role with extensive strength training experience participated in this study. Muscular performance testing examined the force, velocity, and power capabilities of the upper-body musculature, with upper-body push (bench press) and pull (bench pull) movements performed across loads of 10-100% of 1 repetition maximum (1RM). Functional grinding performance was examined for both forward and backward grinding and at 2 different resistances (moderate = 48 N x m, heavy = 68 N x m) using a land-based ergometer. Bench press 1RM and maximum force capability were the measures demonstrating the strongest correlation with forward grinding performance (r = 0.88-0.99 and 0.87-0.99, respectively), with the relationship increasing with grinding load. For backward grinding, there was a very strong relationship with bench pull maximum power (r = 0.85-0.98) in addition to 1RM (r = 0.90-0.95) and maximum force (r = 0.87-0.95). It appears that although maximal strength is a crucial muscular performance characteristic for grinding performance in all conditions, for backward grinding, there is the additional need to focus on the development of speed strength/power to maximize performance gains. This information was used by the Emirates Team New Zealand physical conditioner to develop a conditioning intervention to help improve grinding performance. PMID:19675468

  11. Working with the superabrasives industry to optimize tooling for grinding brittle materials

    SciTech Connect

    Taylor, J.S.; Piscotty, M.A.; Blaedel, K.L.; Gray, F.A.

    1996-12-31

    This paper addresses efforts to optimize fine grinding wheels to support new generation computer-numeric-controlled (CNC) equipment for the optics manufacturing industry. An approach is presented for improving the linkage between users and makers of fine diamond grinding wheels. The proposal includes a voluntary product standard that uses performance indicators to link user requirements and wheel formulations without compromising proprietary information of either party. In addition, technologies that might be required to achieve optimized grinding wheels are addressed.

  12. Grinding Si3N4 Powder In Si3N4 Equipment

    NASA Technical Reports Server (NTRS)

    Herbell, Thomas P.; Freedman, Marc R.; Kiser, James D.

    1989-01-01

    Three methods of grinding compared. Report based on study of grinding silicon nitride powder in preparation for sintering into solid ceramic material. Attrition, vibratory, and ball mills lined with reaction-bonded silicon nitride tested. Rates of reduction of particle sizes and changes in chemical compositions of powders measured so grinding efficiences and increases in impurity contents from wear of mills and media evaluated for each technique.

  13. An experimental assessment on the performance of different lubrication techniques in grinding of Inconel 751.

    PubMed

    Balan, A S S; Vijayaraghavan, L; Krishnamurthy, R; Kuppan, P; Oyyaravelu, R

    2016-09-01

    The application of emulsion for combined heat extraction and lubrication requires continuous monitoring of the quality of emulsion to sustain a desired grinding environment; this is applicable to other grinding fluids as well. Thus to sustain a controlled grinding environment, it is necessary to adopt an effectively lubricated wheel-work interface. The current study was undertaken to assess experimentally the ​ effects of different grinding environments such as dry, minimum quantity lubrication (MQL) and Cryo-MQL on performance, such as grinding force, temperature, surface roughness and chip morphology on Inconel 751, a higher heat resistance material posing thermal problems and wheel loading. The results show that grinding with the combination of both liquid nitrogen (LN2) and MQL lowers temperature, cutting forces, and surface roughness as compared with MQL and dry grinding. Specific cutting energy is widely used as an inverse measure of process efficiency in machining. It is found from the results that specific cutting energy of Cryo-MQL assisted grinding is 50-65% lower than conventional dry grinding. The grindability of Inconel 751 superalloy can be enhanced with Cryo-MQL condition. PMID:27621941

  14. Evaluation of minimum quantity lubrication grinding with nano-particles and recent related patents.

    PubMed

    Li, Changhe; Wang, Sheng; Zhang, Qiang; Jia, Dongzhou

    2013-06-01

    In recent years, a large number of patents have been devoted to developing minimum quantity lubrication (MQL) grinding techniques that can significantly improve both environmentally conscious and energy saving and costeffective sustainable grinding fluid alternatives. Among them, one patent is about a supply system for the grinding fluid in nano-particle jet MQL, which produced MQL lubricant by adding solid nano-particles in degradable grinding fluid. The MQL supply device turns the lubricant to the pulse drops with fixed pressure, unchanged pulse frequency and the same drop diameter. The drops will be produced and injected in the grinding zone in the form of jet flow under high pressure gas and air seal. As people become increasingly demanding on our environment, minimum quantity lubrication has been widely used in the grinding and processing. Yet, it presents the defect of insufficient cooling performance, which confines its development. To improve the heat transfer efficiency of MQL, nano-particles of a certain mass fraction can be added in the minimum quantity of lubricant oil, which concomitantly will improve the lubrication effects in the processing. In this study, the grinding experiment corroborated the effect of nano-particles in surface grinding. In addition, compared with other forms of lubrication, the results presented that the grinding force, the friction coefficient and specific grinding energy of MQL grinding have been significantly weakened, while G ratio greatly rose. These are attributed to the friction oil-film with excellent anti-friction and anti-wear performance, which is generated nano-particles at the wheel/workpiece interface. In this research, the cooling performance of nano-particle jet MQL was analyzed. Based on tests and experiments, the surface temperature was assayed from different methods, including flood lubricating oil, dry grinding, MQL grinding and nano-particle jet MQL grinding. Because of the outstanding heat transfer

  15. Effect of fiber orientations on surface grinding process of unidirectional C/SiC composites

    NASA Astrophysics Data System (ADS)

    Zhang, Lifeng; Ren, Chengzu; Ji, Chunhui; Wang, Zhiqiang; Chen, Guang

    2016-03-01

    The machining mechanism of woven ceramic matrix composites is one of the most challenging problems in composite application. To elucidate the grinding mechanism of the woven ceramic matrix composites, a new model material consisting of unidirectional CVI-C/SiC was prepared and ground. The composite was ground in three typical directions and the experimental investigation of the surface grinding process for this composite is described. In addition, the micro structural characteristics and grinding mechanism of the composite were analyzed. The result shows that brittle fracture is the dominant removal mechanism for grinding of the C/SiC composites, and the destroy form of the composites is mainly the syntheses of the matrix cracking, fiber fracture, and interfacial debonding. The grinding force follows the order: Normal > Longitudinal > Transverse, and the surface roughness follows: Longitudinal > Normal > Transverse. The grinding parameters (feed speed, cut depth, grinding speed) have great influence on the grinding force and surface roughness. Based on the findings, the grinding force and surface integrity of the woven ceramic matrix composites can be predicted. Furthermore, it is expected to provide a useful guideline for the design, evaluation and optimal application of the C/SiC composites.

  16. Finishing of additively manufactured titanium alloy by shape adaptive grinding (SAG)

    NASA Astrophysics Data System (ADS)

    Beaucamp, Anthony T.; Namba, Yoshiharu; Charlton, Phillip; Jain, Samyak; Graziano, Arthur A.

    2015-06-01

    In recent years, rapid prototyping of titanium alloy components for medical and aeronautics application has become viable thanks to advances in technologies such as electron beam melting (EBM) and selective laser sintering (SLS). However, for many applications the high surface roughness generated by additive manufacturing techniques demands a post-finishing operation to improve the surface quality prior to usage. In this paper, the novel shape adaptive grinding process has been applied to finishing titanium alloy (Ti6Al4V) additively manufactured by EBM and SLS. It is shown that the micro-structured surface layer resulting from the melting process can be removed, and the surface can then be smoothed down to less than 10 nm Ra (starting from 4-5 μm Ra) using only three different diamond grit sizes. This paper also demonstrates application of the technology to freeform shapes, and documents the dimensional accuracy of finished artifacts.

  17. Dissolution enhancement of atorvastatin calcium by co-grinding technique.

    PubMed

    Prabhu, Priyanka; Patravale, Vandana

    2016-08-01

    Atorvastatin calcium (AC) is a BCS class II drug which shows poor bioavailability due to inadequate dissolution. Solid dispersions present a promising option to enhance the solubility of poorly soluble drugs. Co-grinding with hydrophilic excipients is an easy and economical technique to improve the solubility of poorly soluble drugs and is free from usage of organic solvents. The aim of the present study was to explore novel carrier VBP-1 (organosulphur compound) for formulating a solid dispersion by using a simple, commercially viable co-grinding technique to enhance the dissolution of AC and to develop an oral formulation of the same. Composition of the solid dispersion was optimized based on the release profile in pH 1.2 buffer. The optimized solid dispersion was further characterized for flow properties, DSC, FTIR spectroscopy, XRD, contact angle, SEM studies and release profile in phosphate buffer pH 6.8. The developed solid dispersion gave similar release profile as the innovator formulation (Lipitor® tablets) in both pH 1.2 buffer and phosphate buffer pH 6.8. The developed solid dispersion was formulated into hard gelatin capsules (size 3). The developed capsules were found to give similar release as the innovator formulation in both pH 1.2 buffer and phosphate buffer pH 6.8. The developed capsules were found to be stable for a period of 6 months. Anti-hyperlipidemic efficacy studies in rats showed higher reduction in cholesterol and triglyceride levels by the developed capsules in comparison to pure AC. In conclusion, novel carrier VBP-1 was successfully employed to enhance the dissolution of AC using co-grinding technique. PMID:26712124

  18. Deaths and tumors among workers grinding stainless steel

    SciTech Connect

    Svensson, B.G.; Englander, V.; Akesson, B.; Attewell, R.; Skerfving, S.; Ericson, A.; Moeller, T.

    1989-01-01

    This study examined a cohort of 1,164 males who, during the period 1927-1981, had been employed for 3 months or more in an industry that produced objects from stainless steel. These workers were exposed to the dust of grinding materials, grinding agents, and stainless steel. From 1975 to 1980, measurements of the total dust in the workroom air have shown levels of about one mg/m3 (consisting of chromium at about 0.1 mg/m3 and nickel at about 0.05 mg/m3) during grinding and several mg/m3 (chromium at about 0.01 mg/m3 and nickel at about 0.005 mg/m3) during polishing. Before 1950, the concentrations were probably considerably higher. Compared to a local reference population, a decrease in mortality (63 observed deaths, standardized mortality (SMR) = 0.79, 95% confidence limits CL = 0.61, 1.01) took place during the 1951-1983 observation period among 318 subjects who had been employed for at least five years, allowing a latency period of at least 20 years. Mortality from cancer of the colon/rectum increased (observed deaths = 6, SMR = 2.47, CL = 0.97, 5.58). The mortality from nonmalignant pulmonary disease did not increase (SMR = 0.29, CL = 0.01, 1.81). During the observation period (1958-1983), there was no significant overall excess of tumors (observed cases = 33, standardized morbidity (SMR) = 1.09, CL = 0.76, 1.54). However, tumor morbidity of the colon/rectum (observed 11, SMR = 2.83, CL = 1.47, 5.19) significantly increased. There were no cases of respiratory cancer (expected 4.7, CL = 0, 0.21). Thus, the results indicate an increased risk of intestinal cancer.

  19. Structure Optimization and Evaluation of Small Adjustable Diameter Grinding Wheel

    NASA Astrophysics Data System (ADS)

    Yao, Yiyong; Li, Yuanyuan; Zhao, Liping; Zhao, Hu

    Focus on the uneven deformation of conventional adjustable diameter grinding wheel (ADGW), a structure optimization and evaluation method of ADGW was proposed in this paper. Firstly, the evaluation index system and structure optimization framework of ADGW was established to obtain the optimization objective of ADGW. Then a simulated experiment was provided. The flexible units of ADGW with different structures and geometries were selected to analyze the unevenness of deformation. The comparison results showed that the proposed method can improve the ADGW structures effectively and provide a technical approach for evaluating the structure design of ADGW.

  20. Development of an `intelligent grinding wheel` for in-process monitoring of ceramic grinding. Semi-annual report No. 2, March 1, 1997--August 31, 1997

    SciTech Connect

    Malkin, S.; Gao, R.; Guo, C.; Varghese, B.; Pathare, S.

    1997-09-29

    The overall objective of this project is to develop sensor-integrated `intelligent` diamond wheels for grinding ceramics. Such wheels will be `smart` enough to monitor and supervise both the wheel preparation and grinding processes without the need to instrument the machine tool. Intelligent wheels will utilize re-useable cores integrated with two types of sensors: acoustic emission (AE) and dynamic force transducers. Signals from the sensors will be transmitted from a rotating wheel to a receiver by telemetry. Intelligent wheels will be `trained` to recognize distinct characteristics associated with truing, dressing and grinding.

  1. Cathode Effects in Cylindrical Hall Thrusters

    SciTech Connect

    Granstedt, E.M.; Raitses, Y.; Fisch, N. J.

    2008-09-12

    Stable operation of a cylindrical Hall thruster (CHT) has been achieved using a hot wire cathode, which functions as a controllable electron emission source. It is shown that as the electron emission from the cathode increases with wire heating, the discharge current increases, the plasma plume angle reduces, and the ion energy distribution function shifts toward higher energies. The observed effect of cathode electron emission on thruster parameters extends and clarifies performance improvements previously obtained for the overrun discharge current regime of the same type of thruster, but using a hollow cathode-neutralizer. Once thruster discharge current saturates with wire heating, further filament heating does not affect other discharge parameters. The saturated values of thruster discharge parameters can be further enhanced by optimal placement of the cathode wire with respect to the magnetic field.

  2. Cathode effects in cylindrical Hall thrusters

    SciTech Connect

    Granstedt, E. M.; Raitses, Y.; Fisch, N. J.

    2008-11-15

    Stable operation of a cylindrical Hall thruster has been achieved using a hot wire cathode, which functions as a controllable electron emission source. It is shown that as the electron emission from the cathode increases with wire heating, the discharge current increases, the plasma plume angle reduces, and the ion energy distribution function shifts toward higher energies. The observed effect of cathode electron emission on thruster parameters extends and clarifies performance improvements previously obtained for the overrun discharge current regime of the same type of thruster, but using a hollow cathode neutralizer. Once thruster discharge current saturates with wire heating, further filament heating does not affect other discharge parameters. The saturated values of thruster discharge parameters can be further enhanced by optimal placement of the cathode wire with respect to the magnetic field.

  3. Changes in the aromatic profile of espresso coffee as a function of the grinding grade and extraction time: a study by the electronic nose system.

    PubMed

    Severini, C; Ricci, I; Marone, M; Derossi, A; De Pilli, T

    2015-03-01

    The changes in chemical attributes and aromatic profile of espresso coffee (EC) were studied taking into account the extraction time and grinding level as independent variables. Particularly, using an electronic nose system, the changes of the global aromatic profile of EC were highlighted. The results shown as the major amounts of organic acids, solids, and caffeine were extracted in the first 8 s of percolation. The grinding grade significantly affected the quality of EC probably as an effect of the particle size distribution and the percolation pathways of water through the coffee cake. The use of an electronic nose system allowed us to discriminate the fractions of the brew as a function of the percolation time and also the regular coffee obtained from different grinding grades. Particularly, the aromatic profile of a regular coffee (25 mL) was significantly affected by the grinding level of the coffee grounds and percolation time, which are two variables under the control of the bar operator. PMID:25665600

  4. Supercooling Water in Cylindrical Capsules

    NASA Astrophysics Data System (ADS)

    Guzman, J. J. Milón; Braga, S. L.

    2005-11-01

    An experimental apparatus was developed to investigate the supercooling phenomenon of water inside cylindrical capsules used for a cold storage process. The coolant is a water-alcohol mixture controlled by a constant temperature bath (CTB). Temperatures varying with time are measured inside and outside the capsule. Cylinders with an internal diameter and thickness of 45 and 1.5 mm, respectively, were made from four different materials: acrylic, PVC, brass, and aluminum. The supercooling period of the water and the nucleation temperature were investigated for different coolant temperatures. The supercooling and nucleation probabilities are shown as a function of the coolant temperature for the four different materials.

  5. Multi-stable cylindrical lattices

    NASA Astrophysics Data System (ADS)

    Pirrera, Alberto; Lachenal, Xavier; Daynes, Stephen; Weaver, Paul M.; Chenchiah, Isaac V.

    2013-11-01

    We present a cylindrical lattice structure that mimics the behaviour of the virus bacteriophage T4 in having two (or more) stable states which differ in their radii and length. While the virus achieves bistability through molecular mechanisms we use composite materials to exploit the interplay between pre-stress, material properties and structural geometry. We demonstrate (computationally) that multi-stability is a robust phenomenon. We also show (analytically) that it is possible to choose the design variables so that the energy is independent of the radius, thus resulting in every state of the structure being stable.

  6. Effects of imbalance and geometric error on precision grinding machines

    SciTech Connect

    Bibler, J.E.

    1997-06-01

    To study balancing in grinding, a simple mechanical system was examined. It was essential to study such a well-defined system, as opposed to a large, complex system such as a machining center. The use of a compact, well-defined system enabled easy quantification of the imbalance force input, its phase angle to any geometric decentering, and good understanding of the machine mode shapes. It is important to understand a simple system such as the one I examined given that imbalance is so intimately coupled to machine dynamics. It is possible to extend the results presented here to industrial machines, although that is not part of this work. In addition to the empirical testing, a simple mechanical system to look at how mode shapes, balance, and geometric error interplay to yield spindle error motion was modelled. The results of this model will be presented along with the results from a more global grinding model. The global model, presented at ASPE in November 1996, allows one to examine the effects of changing global machine parameters like stiffness and damping. This geometrically abstract, one-dimensional model will be presented to demonstrate the usefulness of an abstract approach for first-order understanding but it will not be the main focus of this thesis. 19 refs., 36 figs., 10 tables.

  7. Application of electrolytic in-process dressing for high-efficiency grinding of ceramic parts. Research activities 1995--96

    SciTech Connect

    Bandyopadhyay, B.P.

    1997-02-01

    The application of Electrolytic In-Process Dressing (ELID) for highly efficient and stable grinding of ceramic parts is discussed. This research was performed at the Institute of Physical and Chemical Research (RIKEN), Tokyo, Japan, June 1995 through August 1995. Experiments were conducted using a vertical machining center. The silicon nitride work material, of Japanese manufacture and supplied in the form of a rectangular block, was clamped to a vice which was firmly fixed on the base of a strain gage dynamometer. The dynamometer was clamped on the machining center table. Reciprocating grinding was performed with a flat-faced diamond grinding wheel. The output from the dynamometer was recorded with a data acquisition system and the normal component of the force was monitored. Experiments were carried out under various cutting conditions, different ELID conditions, and various grinding wheel bonds types. Rough grinding wheels of grit sizes {number_sign}170 and {number_sign}140 were used in the experiments. Compared to conventional grinding, there was a significant reduction in grinding force with ELID grinding. Therefore, ELID grinding can be recommended for high material removal rate grinding, low rigidity machines, and low rigidity workpieces. Compared to normal grinding, a reduction in grinding ratio was observed when ELID grinding was performed. A negative aspect of the process, this reduced G-ratio derives from bond erosion and can be improved somewhat by adjustments in the ELID current. The results of this investigation are discussed in detail in this report.

  8. Models of cylindrical bubble pulsation

    PubMed Central

    Ilinskii, Yurii A.; Zabolotskaya, Evgenia A.; Hay, Todd A.; Hamilton, Mark F.

    2012-01-01

    Three models are considered for describing the dynamics of a pulsating cylindrical bubble. A linear solution is derived for a cylindrical bubble in an infinite compressible liquid. The solution accounts for losses due to viscosity, heat conduction, and acoustic radiation. It reveals that radiation is the dominant loss mechanism, and that it is 22 times greater than for a spherical bubble of the same radius. The predicted resonance frequency provides a basis of comparison for limiting forms of other models. The second model considered is a commonly used equation in Rayleigh-Plesset form that requires an incompressible liquid to be finite in extent in order for bubble pulsation to occur. The radial extent of the liquid becomes a fitting parameter, and it is found that considerably different values of the parameter are required for modeling inertial motion versus acoustical oscillations. The third model was developed by V. K. Kedrinskii [Hydrodynamics of Explosion (Springer, New York, 2005), pp. 23–26] in the form of the Gilmore equation for compressible liquids of infinite extent. While the correct resonance frequency and loss factor are not recovered from this model in the linear approximation, it provides reasonable agreement with observations of inertial motion. PMID:22978863

  9. Loads for pulsed power cylindrical implosion experiments

    SciTech Connect

    Anderson, W.E.; Armijo, E.V.; Barthell, B.L.; Bartos, J.J.; Bush, H.; Foreman, L.R.; Garcia, F.P.; Gobby, P.L.; Gomez, V.M.; Gurule, V.A.

    1994-07-01

    Pulse power can be used to generate high energy density conditions in convergent hollow cylindrical geometry through the use of appropriate electrode configuration and cylindrical loads. Cylindrically symmetric experiments are conducted with the Pegasus-H inductive store, capacitor energized pulse power facility at Los Alamos using both precision machined cylindrical liner loads and low mass vapor deposited cylindrical foil loads. The liner experiments investigate solid density hydrodynamic topics. Foil loads vaporize from Joule heating to generate an imploding cylindrical plasma which can be used to simulate some fluxes associated with fusion energy processes. Similar experiments are conducted with {open_quotes}Procyon{close_quotes} inductive store pulse power assemblies energized by explosively driven magnetic flux compression.

  10. Evaporator fouling tendencies of thin stillage and concentrates from the dry grind process

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the US, more than 200 maize processing plants use multiple effect evaporators to remove water from thin stillage and steepwater during dry grind and wet milling processes, respectively. During the dry grind process, unfermentables are centrifuged and the liquid fraction, thin stillage, is concen...

  11. Maize proximate composition and physical properties correlations to dry-grind ethanol concentrations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dry grind ethanol plants incur economic losses due to seasonal variations in ethanol yields. One possible cause associated with ethanol yield variability is incoming grain quality. There is little published information on factors causing variation in dry grind ethanol concentrations. The objective o...

  12. Changes in Composition and Phosphorus Profile during Dry Grind Process of Corn into Ethanol and DDGS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Demand for alternatives to fossil fuels has resulted in a dramatic increase in ethanol production from corn. Dry grind method has been a major process, resulting in a large volume of dried distiller grains with solubles (DDGS) as a co-product. The process consists of grinding, cooking, liquefactio...

  13. [Neuro-occlusal rehabilitation and selective grinding: results after 1 year].

    PubMed

    Martin, E

    2000-01-01

    The aim of this work is to illustrate the results, one year after selective grindings have been used in "Neuro-Occlusal Rehabilitation" (N.O.R.). These selective grindings have been described by Pr Planas and are used to free mandibular lateral movements, in order to facilitate correct development of the stomatognathic system. PMID:10838864

  14. Capturing action of cooling lubricants in grinding and evaluation of its effectiveness

    NASA Astrophysics Data System (ADS)

    Tyukhta, A. V.; Khandozhko, A. V.; Vasilenko, Yu V.

    2016-04-01

    Methods of coolant supply are considered to be aiming at capturing and neutralization of the flare of grinding waste and noxious coolant fumes during flat grinding with a wheel periphery. Study and evaluation of the new coolant functional property – capturing – are presented.

  15. A Novel Vibration Mode Testing Method for Cylindrical Resonators Based on Microphones

    PubMed Central

    Zhang, Yongmeng; Wu, Yulie; Wu, Xuezhong; Xi, Xiang; Wang, Jianqiu

    2015-01-01

    Non-contact testing is an important method for the study of the vibrating characteristic of cylindrical resonators. For the vibratory cylinder gyroscope excited by piezo-electric electrodes, mode testing of the cylindrical resonator is difficult. In this paper, a novel vibration testing method for cylindrical resonators is proposed. This method uses a MEMS microphone, which has the characteristics of small size and accurate directivity, to measure the vibration of the cylindrical resonator. A testing system was established, then the system was used to measure the vibration mode of the resonator. The experimental results show that the orientation resolution of the node of the vibration mode is better than 0.1°. This method also has the advantages of low cost and easy operation. It can be used in vibration testing and provide accurate results, which is important for the study of the vibration mode and thermal stability of vibratory cylindrical gyroscopes. PMID:25602269

  16. Propagation Mechanism of Cylindrical Cellular Detonation

    NASA Astrophysics Data System (ADS)

    Han, Wen-Hu; Wang, Cheng; Ning, Jian-Guo

    2012-10-01

    We investigate the evolution of cylindrical cellular detonation with different instabilities. The numerical results show that with decreasing initial temperature, detonation becomes more unstable and the cells of the cylindrical detonation tend to be irregular. For stable detonation, a divergence of cylindrical detonation cells is formed eventually due to detonation instability resulting from a curved detonation front. For mildly unstable detonation, local overdriven detonation occurs. The detonation cell diverges and its size decreases. For highly unstable detonation, locally driven detonation is more obvious and the front is highly wrinkled. As a result, the diverging cylindrical detonation cell becomes highly irregular.

  17. Investigation of the Formation Process of Two Piracetam Cocrystals during Grinding

    PubMed Central

    Rehder, Sönke; Klukkert, Marten; Löbmann, Korbinian A. M.; Strachan, Clare J.; Sakmann, Albrecht; Gordon, Keith; Rades, Thomas; Leopold, Claudia S.

    2011-01-01

    Cocrystal formation rates during dry grinding and liquid-assisted grinding were investigated by X-ray powder diffractometry and Raman spectroscopy. Two polymorphic forms of piracetam were used to prepare known piracetam cocrystals as model substances, i.e., piracetam-citric acid and piracetam-tartaric acid cocrystals. Raman spectroscopy in combination with principal component analysis was used to visualize the cocrystal formation pathways. During dry grinding, cocrystal formation appeared to progress via an amorphous intermediate stage, which was more evident for the piracetam-citric acid than for the piracetam-tartaric acid cocrystal. It was shown that liquid-assisted grinding led to faster cocrystal formation than dry grinding, which may be explained by the higher transformation rate due to the presence of liquid. The cocrystal formation rate did not depend on the applied polymorphic form of the piracetam and no polymorphic cocrystals were obtained. PMID:24309304

  18. Comparison of Materials for Use in the Precision Grinding of Optical Components

    SciTech Connect

    Evans, Boyd M. III; Miller, Arthur C. Jr.; Egert, Charles M.

    1997-12-31

    Precision grinding of optical components is becoming an accepted practice for rapidly and deterministically fabrication optical surfaces to final or near-final surface finish and figure. In this paper, a comparison of grinding techniques and materials is performed. Flat and spherical surfaces were ground in three different substrate materials: BK7 glass, chemical vapor deposited (CVD) silicon carbide ceramic, and sapphire. Spherical surfaces were used to determine the contouring capacity of the process, and flat surfaces were used for surface finish measurements. The recently developed Precitech Optimum 2800 diamond turning and grinding platform was used to grind surfaces in 40mm diameter substrates sapphire and silicon carbide substrates and 200 mm BK7 glass substrates using diamond grinding wheels. The results of this study compare the surface finish and figure for the three materials.

  19. Study on grinding of free-form optics surface in three-axis CNC machine

    NASA Astrophysics Data System (ADS)

    Yang, Haicheng; Zhang, Yun-long; Zhang, Feng; Wang, Zhibin; Bao, Long-xiang; Su, Ying; Guo, Rui; Liu, Xuan-min

    2014-08-01

    Due to the glass is a type of brittle material, so the high-precision free-form optics of glass material is usually machined by the technical of grinding. In this paper, for the characteristics of the diamond grinding wheel, analyzing the grinding path of free-form optics and mathematical model of the path is established based on the three-axis CNC grinding device. Moreover, the cause of the interference in the process of grinding is analyzed and the methods of avoiding. Finally, based on the above analysis results, through the experiment, the free-form optics surface accuracy was reached to 3.6um, realize the machining of the free-form optics.

  20. Comparison of tungsten carbide and stainless steel ball bearings for grinding single maize kernels in a reciprocating grinder

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reciprocating grinders can grind single maize kernels by shaking the kernel in a vial with a ball bearing. This process results in a grind quality that is not satisfactory for many experiments. Tungesten carbide ball bearings are nearly twice as dense as steel, so we compared their grinding performa...

  1. Automated inspection and precision grinding of spiral bevel gears

    NASA Technical Reports Server (NTRS)

    Frint, Harold

    1987-01-01

    The results are presented of a four phase MM&T program to define, develop, and evaluate an improved inspection system for spiral bevel gears. The improved method utilizes a multi-axis coordinate measuring machine which maps the working flank of the tooth and compares it to nominal reference values stored in the machine's computer. A unique feature of the system is that corrective grinding machine settings can be automatically calculated and printed out when necessary to correct an errant tooth profile. This new method eliminates most of the subjective decision making involved in the present method, which compares contact patterns obtained when the gear set is run under light load in a rolling test machine. It produces a higher quality gear with significant inspection time and cost savings.

  2. Operations

    ERIC Educational Resources Information Center

    Wilkins, Jesse L. M.; Norton, Anderson; Boyce, Steven J.

    2013-01-01

    Previous research has documented schemes and operations that undergird students' understanding of fractions. This prior research was based, in large part, on small-group teaching experiments. However, written assessments are needed in order for teachers and researchers to assess students' ways of operating on a whole-class scale. In this…

  3. Observations of ion-acoustic cylindrical solitons

    NASA Technical Reports Server (NTRS)

    Hershkowitz, N.; Romesser, T.

    1974-01-01

    Experimental observations of cylindrical solitons in a collisionless plasma are presented. The data obtained show that cylindrical solitonlike objects exist and that their properties are consistent with those of one- and three-dimensional solitons. It is found that compressive density perturbations evolve into solitons. The number of the solitons is determined by the width and amplitude of the applied pulse.

  4. Cylindrical Hall Thrusters with Permanent Magnets

    SciTech Connect

    Raitses, Yevgeny; Merino, Enrique; Fisch, Nathaniel J.

    2010-10-18

    The use of permanent magnets instead of electromagnet coils for low power Hall thrusters can offer a significant reduction of both the total electric power consumption and the thruster mass. Two permanent magnet versions of the miniaturized cylindrical Hall thruster (CHT) of different overall dimensions were operated in the power range of 50W-300 W. The discharge and plasma plume measurements revealed that the CHT thrusters with permanent magnets and electromagnet coils operate rather differently. In particular, the angular ion current density distribution from the permanent magnet thrusters has an unusual halo shape, with a majority of high energy ions flowing at large angles with respect to the thruster centerline. Differences in the magnetic field topology outside the thruster channel and in the vicinity of the channel exit are likely responsible for the differences in the plume characteristics measured for the CHTs with electromagnets and permanent magnets. It is shown that the presence of the reversing-direction or cusp-type magnetic field configuration inside the thruster channel without a strong axial magnetic field outside the thruster channel does not lead to the halo plasma plume from the CHT. __________________________________________________

  5. Cylindrical millimeter-wave imaging technique for concealed weapon detection

    NASA Astrophysics Data System (ADS)

    Sheen, David M.; McMakin, Douglas L.; Hall, Thomas E.

    1998-03-01

    A novel cylindrical millimeter-wave imaging technique has been developed at the Pacific Northwest National Laboratory for the detection of metallic and non-metallic concealed weapons. This technique uses a vertical array of millimeter- wave antennas which is mechanically swept around a person in a cylindrical fashion. The wideband millimeter-wave data is mathematically reconstructed into a series of high- resolution images of the person being screened. Clothing is relatively transparent to millimeter-wave illumination,whereas the human body and concealed items are reflective at millimeter wavelengths. Differences in shape and reflectivity are revealed in the images and allow a human operator to detect and identify concealed weapons. A full 360 degree scan is necessary to fully inspect a person for concealed items. The millimeter-wave images can be formed into a video animation sequence in which the person appears to rotate in front of a fixed illumination source.This is s convenient method for presenting the 3D image data for analysis. This work has been fully sponsored by the FAA. An engineering prototype based on the cylindrical imaging technique is presently under development. The FAA is currently opposed to presenting the image data directly to the operator due to personal privacy concerns. A computer automated system is desired to address this problem by eliminating operator viewing of the imagery.

  6. Intra-pulp temperature increase of equine cheek teeth during treatment with motorized grinding systems: influence of grinding head position and rotational speed

    PubMed Central

    2014-01-01

    Background In equine practice, teeth corrections by means of motorized grinding systems are standard procedure. The heat resulting from that treatment may cause irreparable damage to the dental pulp. It has been shown that a 5.5°C temperature rise may cause severe destruction in pulp cells. Hence, the capability to continuously form secondary dentine is lost, and may lead, due to equine-typical occlusal tooth abrasion, to an opening of the pulp cavity. To obtain reliable data on the intra-pulp increase in temperature during corrective treatments, equine cheek teeth (CT) were modified in a way (occlusal surface smoothed, apical parts detached, pulp horns standardized) that had been qualified in own former published studies. All parameters influencing the grinding process were standardized (force applied, initial temperatures, dimensions of pulp horns, positioning of grinding disk, rotational speed). During grinding experiments, imitating real dental treatments, the time span for an intra-pulp temperature increase of 5.5°C was determined. Results The minimum time recorded for an intra-pulp temperature increase of 5.5°C was 38 s in mandibular CT (buccal grinding, 12,000 rpm) and 70 s in maxillary CT (flat occlusal grinding, 12,000 rpm). The data obtained showed that doubling the rotational speed of the disk results in halving the time span after which the critical intra-pulp temperature increase in maxillary CT is reached. For mandibular CT, the time span even drops by two thirds. Conclusion The use of standardized hypsodont CT enabled comparative studies of intra-pulp heating during the grinding of occlusal tooth surfaces using different tools and techniques. The anatomical structure of the natural vital hypsodont tooth must be kept in mind, so that the findings of this study do not create a deceptive sense of security with regard to the time-dependent heating of the native pulp. PMID:24559121

  7. Novel grinding stone used for polishing 3D plastic replica with rapid prototyping technology

    NASA Astrophysics Data System (ADS)

    Feng, Wang; Niikura, Yoshihiro; Sato, Toshio; Kawashima, Norimichi

    2006-01-01

    Rapid prototyping (RP) apparatus accepts a specific format translated from CAD data (patient's CT) and "slices" it into two-dimensional cross sections for laser photo curing. Surgeon can conduct safer surgery by reappearing on an actual model using 3D plastic replica in the preoperative. Polishing has to be used to eliminate the marks after removal of supports and the build layer pitches. Complicated and narrow areas of the 3D replica are difficult to be polished with the conventional grinding stone. This study proposes a novel grinding stone and introduces its producing process and characteristics. The novel grinding stone has many advantages as follows; (1) Preparation is possible of grinding stone that follows the complicated shape. (2) Grinding stone with uniformly dispersed abrasive grains can be prepared using magnetic particles and magnetic field. (3) Reshaping of grinding stone by heating is possible since the binder is made of a thermoplastic resin. (4) Every process can easily be carried out. We could polish to eliminate the marks after removal of supports and the build layer pitches on 3D plastic replica surface with the grinding stone.

  8. Emissivity calibration for temperature measurement using infrared thermography in orthogonal cutting of 316L and 100Cr6 grinding

    NASA Astrophysics Data System (ADS)

    Valiorgue, Frédéric; Brosse, Alexandre; Rech, Joël; Hamdi, Hédi; Bergheau, Jean Michel

    2011-01-01

    Material removal operations such as turning or grinding are prone to generate very high temperatures at the tool/chip and tool/workpiece interfaces. These phenomena are involved in studies concerning tools or workpieces, and their estimation is a key point for predicting damages. Temperature elevation is the main cause in workpieces worsening because it generates residual stresses and metallurgical modifications. It is also linked to the tools wear because of the thermal fatigue phenomena and the thermally activated diffusion process. In this paper, a first attempt to measure the temperature fields during 316L orthogonal cutting and 100Cr6 grinding is presented and can be divided in three parts. In the first part the physics of temperature measurement using infrared thermography are presented. Then, the calibration of the infrared camera is realized and allows to obtain of the emissivity curves of 316L and 100Cr6 steels. To do so, an experimental device has been set up to reproduce the luminance recording conditions encountered during the machining operations. The last step is the computation of all the experimental data to obtain the temperature fields from the recorded luminance and the 316L and 100Cr6 emissivity curve. At last, temperature level measured is compared to those presented in the bibliography.

  9. Improved sulfur removal from coals by redox potential control of surfaces during grinding

    SciTech Connect

    Tampy, G.K.; Birlingmair, D.H.; Burkhart, L.E.

    1988-01-01

    Control of the redox potential of an Upper Freeport run-of-mine coal slurry during wet grinding and subsequent beneficiation gave better sulfur removal, with no decrease in coal recovery, than either potential control during grinding or beneficiation alone. Sodium dithionite, a reducing agent used to depress the sulfur, also gave substantially better results than pH control alone, irrespective of whether the physical beneficiation was by oil agglomeration, foam flotation, or microbubble batch flotation. Three-phase contact angle measurements and pulp potential measurements suggest that slow electrochemical reactions at the particle surfaces may be responsible for the improved results obtained when the reductant is added at the grinding stage.

  10. Process diagnostics for precision grinding brittle materials in a production environment

    SciTech Connect

    Blaedel, K L; Davis, P J; Piscotty, M A

    1999-04-01

    Precision grinding processes are steadily migrating from research laboratory environments into manufacturing production lines as precision machines and processes become increasingly more commonplace throughout industry. Low-roughness, low-damage precision grinding is gaining widespread commercial acceptance for a host of brittle materials including advanced structural ceramics. The development of these processes is often problematic and requires diagnostic information and analysis to harden the processes for manufacturing. This paper presents a series of practical precision grinding tests developed and practiced at Lawrence Livermore National Laboratory that yield important information to help move a new process idea into production.

  11. The grinding behavior of ground copper powder for Cu/CNT nanocomposite fabrication by using the dry grinding process with a high-speed planetary ball mill

    NASA Astrophysics Data System (ADS)

    Choi, Heekyu; Bor, Amgalan; Sakuragi, Shiori; Lee, Jehyun; Lim, Hyung-Tae

    2016-01-01

    The behavior of ground copper powder for copper-carbon nanotube (copper-CNT) nanocomposite fabrication during high-speed planetary ball milling was investigated because the study of the behavior characteristics of copper powder has recently gained scientific interest. Also, studies of Cu/CNT composites have widely been done due to their useful applications to enhanced, advanced nano materials and components, which would significantly improve the properties of new mechatronics-integrated materials and components. This study varied experimental conditions such as the rotation speed and the grinding time with and without CNTs, and the particle size distribution, median diameter, crystal structure and size, and particle morphology were monitored for a given grinding time. We observed that pure copper powders agglomerated and that the morphology changed with changing rotation speed. The particle agglomerations were observed with maximum experiment conditions (700 rpm, 60 min) in this study of the grinding process for mechanical alloys in the case of pure copper powders because the grinding behavior of Cu/CNT agglomerations was affected by the addition of CNTs. Indeed, the powder morphology and the crystal size of the composite powder could be changed by increasing the grinding time and the rotation speed.

  12. Development of an ``intelligent grinding wheel`` for in-process monitoring of ceramic grinding. Semi-annual report {number_sign}4

    SciTech Connect

    Malkin, S.; Gao, R.; Guo, C.; Varghese, B.; Pathare, S.

    1998-09-30

    The overall objective of this project is to develop sensor-integrated ``intelligent`` diamond wheels for grinding of ceramics. Such wheels will be ``smart`` enough to monitor and supervise both the wheel preparation and grinding processes without the need to instrument the machine tool. Intelligent wheels will utilize re-useable cores integrated with sensors: to measure the acoustic emission (AE) and grinding force. Signals from the sensors will be transmitted from a rotating wheel to a receiver by telemetry. Wheels will be ``trained`` to recognize distinct characteristics associated with truing, dressing and grinding. This overall project is divided into six tasks as follows: (1) development of miniaturized sensors and data transmission system; (2) wheel design and sensor configuration; (3) calibration of the sensor integrated wheel; (4) training of the intelligent wheel; (5) grinding tests; and (6) prototype demonstration. The technical progress is summarized in this report according to the tasks. All activity during this period has been concerned with the first two interrelated tasks, which need to be completed before undertaking the remaining tasks.

  13. Growing Yeast into Cylindrical Colonies

    PubMed Central

    Vulin, Clément; Di Meglio, Jean-Marc; Lindner, Ariel B.; Daerr, Adrian; Murray, Andrew; Hersen, Pascal

    2014-01-01

    Microorganisms often form complex multicellular assemblies such as biofilms and colonies. Understanding the interplay between assembly expansion, metabolic yield, and nutrient diffusion within a freely growing colony remains a challenge. Most available data on microorganisms are from planktonic cultures, due to the lack of experimental tools to control the growth of multicellular assemblies. Here, we propose a method to constrain the growth of yeast colonies into simple geometric shapes such as cylinders. To this end, we designed a simple, versatile culture system to control the location of nutrient delivery below a growing colony. Under such culture conditions, yeast colonies grow vertically and only at the locations where nutrients are delivered. Colonies increase in height at a steady growth rate that is inversely proportional to the cylinder radius. We show that the vertical growth rate of cylindrical colonies is not defined by the single-cell division rate, but rather by the colony metabolic yield. This contrasts with cells in liquid culture, in which the single-cell division rate is the only parameter that defines the population growth rate. This method also provides a direct, simple method to estimate the metabolic yield of a colony. Our study further demonstrates the importance of the shape of colonies on setting their expansion. We anticipate that our approach will be a starting point for elaborate studies of the population dynamics, evolution, and ecology of microbial colonies in complex landscapes. PMID:24853750

  14. Filling of charged cylindrical capillaries.

    PubMed

    Das, Siddhartha; Chanda, Sourayon; Eijkel, J C T; Tas, N R; Chakraborty, Suman; Mitra, Sushanta K

    2014-10-01

    We provide an analytical model to describe the filling dynamics of horizontal cylindrical capillaries having charged walls. The presence of surface charge leads to two distinct effects: It leads to a retarding electrical force on the liquid column and also causes a reduced viscous drag force because of decreased velocity gradients at the wall. Both these effects essentially stem from the spontaneous formation of an electric double layer (EDL) and the resulting streaming potential caused by the net capillary-flow-driven advection of ionic species within the EDL. Our results demonstrate that filling of charged capillaries also exhibits the well-known linear and Washburn regimes witnessed for uncharged capillaries, although the filling rate is always lower than that of the uncharged capillary. We attribute this to a competitive success of the lowering of the driving forces (because of electroviscous effects), in comparison to the effect of weaker drag forces. We further reveal that the time at which the transition between the linear and the Washburn regime occurs may become significantly altered with the introduction of surface charges, thereby altering the resultant capillary dynamics in a rather intricate manner. PMID:25375597

  15. Intrinsic cylindrical and spherical waves

    NASA Astrophysics Data System (ADS)

    Ludlow, I. K.

    2008-02-01

    Intrinsic waveforms associated with cylindrical and spherical Bessel functions are obtained by eliminating the factors responsible for the inverse radius and inverse square radius laws of wave power per unit area of wavefront. The resulting expressions are Riccati-Bessel functions for both cases and these can be written in terms of amplitude and phase functions of order v and wave variable z. When z is real, it is shown that a spatial phase angle of the intrinsic wave can be defined and this, together with its amplitude function, is systematically investigated for a range of fixed orders and varying z. The derivatives of Riccati-Bessel functions are also examined. All the component functions exhibit different behaviour in the near field depending on the order being less than, equal to or greater than 1/2. Plots of the phase angle can be used to display the locations of the zeros of the general Riccati-Bessel functions and lead to new relations concerning the ordering of the real zeros of Bessel functions and the occurrence of multiple zeros when the argument of the Bessel function is fixed.

  16. Support structure for a prestressed cylindrical pressure vessel

    SciTech Connect

    Schoening, J.; Schwiers, H.-G.

    1984-10-02

    A support structure for a nuclear power station having a prestressed cylindrical vessel comprising an annular ring of supports on a support wall and foundation wherein the prestressed cylindrical vessel rests on the ring of supports is disclosed. The supports, through their defined distances from each other, provide a constant cooling flow of the supports and a constant temperature over the entire operating period of the power station. This results in supports that are maintenance-free. The supports are constructed of plastic washers with steel inserts and are of sufficient height such that in the case of earthquakes, maximum vibrations of the reinforced concrete pressure vessel may be absorbed within an accurately set terminal boundary of the annular support wall.

  17. Jet mixing in a reacting cylindrical crossflow

    NASA Technical Reports Server (NTRS)

    Leong, M. Y.; Samuelsen, G. S.; Holdeman, J. D.

    1995-01-01

    This paper addresses the mixing of air jets into the hot, fuel-rich products of a gas turbine primary zone. The mixing, as a result, occurs in a reacting environment with chemical conversion and substantial heat release. The geometry is a crossflow confined in a cylindrical duct with side-wall injection of jets issuing from round orifices. A specially designed reactor, operating on propane, presents a uniform mixture without swirl to mixing modules consisting of 8, 9, 10, and 12 holes at a momentum-flux ratio of 57 and a jet-to-mainstream mass-flow ratio of 2.5. Concentrations of O2, CO2, CO, and HC are obtained upstream, downstream, and within the orifice plane. O2 profiles indicate jet penetration while CO2, CO, and HC profiles depict the extent of reaction. Jet penetration is observed to be a function of the number of orifices and is found to affect the mixing in the reacting system. The results demonstrate that one module (the 12-hole) produces near-optimal penetration defined here as a jet penetration closest to the module half-radius, and hence the best uniform mixture at a plane one duct radius from the orifice leading edge.

  18. Controlling the Plasma Flow in the Miniaturized Cylindrical Hall Thruster

    SciTech Connect

    A. Smirnov, Y. Raitses and N.J. Fisch

    2008-03-04

    A substantial narrowmg of the plume of the cylindrical RaIl thruster (CRT) was observed upon the enhancement of the electron emission from the hollow cathode discharge, which implies the possibility for the thruster efficiency increase due to the ion beam focusing. It is demonstrated that the miniaturized CRT can be operated in the non-self-sustained regime, with the discharge current limited by the cathode electron emission. The thruster operation in this mode greatly expands the range of the plasma and discharge parameters normally accessible for the CRT.

  19. Use of the indentation fracture index to assess coal grinding efficiency

    SciTech Connect

    Yen, S.C.; Hippo, E.J.; Blankenship, M.; Jao, H.; Yen, F.S.

    1994-12-31

    The primary emphasis of this paper is to introduce a methodology that leads to establishing an effective, efficient technique for ultrafine grinding of coal. To be more specific, it is believed that the key to successful coal grinding is strongly dependent upon the change of the brittleness (or fracture resistance) of coal under a freezing temperature pretreatment. Furthermore, a cryogenic grinding process may provide the basis for developing advanced technologies that involve the separation of the pyritic minerals from coal. The specific objectives of this research are to: (1) determine the fracture resistance of coal under different low temperature pretreatments; and (2) determine the relationship between the fracture resistance of coal and the effectiveness of a grinding process.

  20. 8. VIEW TO SOUTHEAST, DRYERS, GRINDING/ROD MILL, MECHANIC SHED, AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. VIEW TO SOUTHEAST, DRYERS, GRINDING/ROD MILL, MECHANIC SHED, AND SKINNER SALT ROASTERS. - Vanadium Corporation of America (VCA) Naturita Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

  1. 7. VIEW TO EAST, MILL WAREHOUSE, DRYERS, GRINDING/ROD MILL, AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. VIEW TO EAST, MILL WAREHOUSE, DRYERS, GRINDING/ROD MILL, AND MECHANIC SHED. - Vanadium Corporation of America (VCA) Naturita Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

  2. 3. VIEW TO NORTHEAST, MECHANIC SHED, DRYERS, GRINDING/ROD MILL, AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. VIEW TO NORTHEAST, MECHANIC SHED, DRYERS, GRINDING/ROD MILL, AND SKINNER SALT ROASTERS. - Vanadium Corporation of America (VCA) Naturita Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

  3. On the limit of surface integrity of alumina by ductile-mode grinding

    SciTech Connect

    Zarudi, I.; Zhang, L.C.

    2000-01-01

    This paper investigates both experimentally and theoretically the subsurface damage in alumina by ductile-mode grinding. It was found that the distribution of the fractured area on a ground mirror surface, with the Rms roughness in the range from 30 nm to 90 nm, depends on not only the grinding conditions but also the pores in the bulk material. Surface pit formation is the result of interaction of abrasive grains of the grinding wheel with pores. Thus the surface quality achievable by ductile-mode grinding is limited by the initial microstructure of a material. The investigation shows that median and radial cracks do not appear and hence are not the cause of fracture as usually thought.

  4. An Efficient, Robust, and Inexpensive Grinding Device for Herbal Samples like Cinchona Bark

    PubMed Central

    Hansen, Steen Honoré; Holmfred, Else; Cornett, Claus; Maldonado, Carla; Rønsted, Nina

    2015-01-01

    An effective, robust, and inexpensive grinding device for the grinding of herb samples like bark and roots was developed by rebuilding a commercially available coffee grinder. The grinder was constructed to be able to provide various particle sizes, to be easy to clean, and to have a minimum of dead volume. The recovery of the sample when grinding as little as 50 mg of crude Cinchona bark was about 60%. Grinding is performed in seconds with no rise in temperature, and the grinder is easily disassembled to be cleaned. The influence of the particle size of the obtained powders on the recovery of analytes in extracts of Cinchona bark was investigated using HPLC. PMID:26839823

  5. Effects of surface grinding conditions on the reciprocating friction and wear behavior of silicon nitride

    SciTech Connect

    Blau, P.J.; Martin, R.L.; Zanoria, E.S.

    1997-12-31

    The relationship between two significantly different surface grinding conditions and the reciprocating ball-on-flat friction and wear behavior of a high-quality, structural silicon nitride material (GS-44) was investigated. The slider materials were silicon nitride NBD 200 and 440C stainless steel. Two machining conditions were selected based on extensive machining and flexural strength test data obtained under the auspices of an international, interlaboratory grinding study. The condition categorized as {open_quotes}low strength{close_quote} grinding used a coarse 80 grit wheel and produced low flexure strength due to machining-induced flaws in the surface. The other condition, regarded as {open_quotes}high strength grinding,{close_quotes} utilized a 320 grit wheel and produced a flexural strength nearly 70% greater. Grinding wheel surface speeds were 35 and 47 m/s. Reciprocating sliding tests were conducted following the procedure described in a newly-published ASTM standard (G- 133) for linearly-reciprocating wear. Tests were performed in directions both parallel and perpendicular to the grinding marks (lay) using a 25 N load, 5 Hz reciprocating frequency, 10 mm stroke length, and 100 m of sliding at room temperature. The effects of sliding direction relative to the lay were more pronounced for stainless steel than for silicon nitride sliders. The wear of stainless steel was less than the wear of the silicon nitride slider materials because of the formation of transfer particles which covered the sharp edges of the silicon nitride grinding grooves and reduced abrasive contact. The wear of the GS-44 material was much greater for the silicon nitride sliders than for the stainless steel sliders. The causes for the effects of surface-grinding severity and sliding direction on friction and wear of GS-44 and its counterface materials are explained.

  6. Effects of metal surface grinding at the porcelain try-in stage of fixed dental prostheses

    PubMed Central

    Kesim, Bülent; Gümüş, Hasan Önder; Dinçel, Mehmet; Erkaya, Selçuk

    2014-01-01

    PURPOSE This study was to evaluate the effect of grinding of the inner metal surface during the porcelain try-in stage on metal-porcelain bonding considering the maximum temperature and the vibration of samples. MATERIALS AND METHODS Ninety-one square prism-shaped (1 × 1 × 1.5 mm) nickel-chrome cast frameworks 0.3 mm thick were prepared. Porcelain was applied on two opposite outer axial surfaces of the frameworks. The grinding was performed from the opposite axial sides of the inner metal surfaces with a low-speed handpiece with two types of burs (diamond, tungsten-carbide) under three grinding forces (3.5 N, 7 N, 14 N) and at two durations (5 seconds, 10 seconds). The shear bond strength (SBS) test was performed with universal testing machine. Statistical analyzes were performed at 5% significance level. RESULTS The samples subjected to grinding under 3.5 N showed higher SBS values than those exposed to grinding under 7 N and 14 N (P<.05). SBS values of none of the groups differed from those of the control group (P>.05). The types of bur (P=.965) and the duration (P=.679) did not affect the SBS values. On the other hand, type of bur, force applied, and duration of the grinding affected the maximum temperatures of the samples, whereas the maximum vibration was affected only by the type of bur (P<.05). CONCLUSION Grinding the inner metal surface did not affect the metal-porcelain bond strength. Although the grinding affected the maximum temperature and the vibration values of the samples, these did not influence the bonding strength. PMID:25177476

  7. Effect of cryogenic grinding on volatile and fatty oil constituents of cumin (Cuminum cyminum L.) genotypes.

    PubMed

    Sharma, L K; Agarwal, D; Rathore, S S; Malhotra, S K; Saxena, S N

    2016-06-01

    Effect of cryogenic grinding on recovery of volatile oil, fatty oil percentage and their constituents in two cumin (Cuminum cyminum L.) genotypes have been analyzed. Cryogenic grinding not only retains the volatiles but enhanced the recovery by 33.9 % in GC 4 and 43.5 % in RZ 209. A significant increase (29.9 %) over normal grinding in oil percentage was also observed in genotype RZ 209. This increase was, however, less (15.4 %) in genotype GC 4. Nineteen major compounds were identified in the essential oil of both genotypes. The two grinding techniques had significant effects on dependent variables, viz., volatile oil and monoterpenes. Cuminaldehyde was the main constituent in both genotypes, content of which increased from 48.2 to 56.1 % in GC 4 on cryo grinding. Content of terpines were found to decrease in cryo ground samples of GC 4 and either decrease or no change was found in RZ 209. Organoleptic test showed more pleasant aroma in cryo ground seeds of both the genotypes. Significant increase was also reported in fatty oil yield due to cryogenic grinding. Fatty acid methyl ester (FAME) analysis showed oleic acid as major FAME content of which increased from 88.1 to 94.9 % in RZ 209 and from 88.2 to 90.1 % in GC 4 on cryogenic grinding. Other prominent FAME were palmitic, palmitoleic and stearic acid. Results indicated commercial potential of cryogenic grinding technology for cumin in general and spices in particular for better retention of flavour and quality in spices. PMID:27478239

  8. Surface roughness of zirconia for full-contour crowns after clinically simulated grinding and polishing.

    PubMed

    Hmaidouch, Rim; Müller, Wolf-Dieter; Lauer, Hans-Christoph; Weigl, Paul

    2014-12-01

    The aim of this study was to evaluate the effect of controlled intraoral grinding and polishing on the roughness of full-contour zirconia compared to classical veneered zirconia. Thirty bar-shaped zirconia specimens were fabricated and divided into two groups (n=15). Fifteen specimens (group 1) were glazed and 15 specimens (group 2) were veneered with feldspathic ceramic and then glazed. Prior to grinding, maximum roughness depth (Rmax) values were measured using a profilometer, 5 times per specimen. Simulated clinical grinding and polishing were performed on the specimens under water coolant for 15 s and 2 N pressure. For grinding, NTI diamonds burs with grain sizes of 20 µm, 10 µm, and 7.5 µm were used sequentially. The ground surfaces were polished using NTI kits with coarse, medium and fine polishers. After each step, Rmax values were determined. Differences between groups were examined using one-way analysis of variance (ANOVA). The roughness of group 1 was significantly lower than that of group 2. The roughness increased significantly after coarse grinding in both groups. The results after glazing were similar to those obtained after fine grinding for non-veneered zirconia. However, fine-ground veneered zirconia had significantly higher roughness than venerred, glazed zirconia. No significant difference was found between fine-polished and glazed zirconia, but after the fine polishing of veneered zirconia, the roughness was significantly higher than after glazing. It can be concluded that for full-contour zirconia, fewer defects and lower roughness values resulted after grinding and polishing compared to veneered zirconia. After polishing zirconia, lower roughness values were achieved compared to glazing; more interesting was that the grinding of glazed zirconia using the NTI three-step system could deliver smooth surfaces comparable to untreated glazed zirconia surfaces. PMID:25059249

  9. Effect of different grinding burs on the physical properties of zirconia

    PubMed Central

    2016-01-01

    PURPOSE Grinding with less stress on 3Y-TZP through proper selection of methods and instruments can lead to a long-term success of prosthesis. The purpose of this study was to compare the phase transformation and physical properties after zirconia surface grinding with 3 different grinding burs. MATERIALS AND METHODS Forty disc-shaped zirconia specimens were fabricated. Each Ten specimens were ground with AllCeramic SuperMax (NTI, Kahla, Germany), Dura-Green DIA (Shofu Inc., Kyoto, Japan), and Dura-Green (Shofu Inc., Kyoto, Japan). Ten specimens were not ground and used as a control group. After the specimen grinding, XRD analysis, surface roughness test, FE-SEM imaging, and biaxial flexural strength test were performed. RESULTS After surface grinding, small amount of monoclinic phase in all experimental groups was observed. The phase change was higher in specimens, which were ground with Dura-Green DIA and AllCeramic SuperMax burs. The roughness of surfaces increased in specimens, which were ground with Dura-Green DIA and AllCeramic SuperMax burs than control groups and ground with Dura-Green. All experimental groups showed lower flexural strength than control group, but there was no statistically significant difference between control group and ground with Dura-Green DIA and AllCeramic SuperMax burs. The specimens, which were ground with Dura- Green showed the lowest strength. CONCLUSION The use of dedicated zirconia-specific grinding burs such as Dura-Green DIA and AllCeramic SuperMax burs decreases the grinding time and did not significantly affect the flexural strength of zirconia, and therefore, they may be recommended. However, a fine polishing process should be accompanied to reduce the surface roughness after grinding. PMID:27141258

  10. Next generation grinding spindle for cost-effective manufacture of advanced ceramic components

    SciTech Connect

    Kovach, J.A.; Laurich, M.A.

    2000-01-01

    Finish grinding of advanced structural ceramics has generally been considered an extremely slow and costly process. Recently, however, results from the High-Speed, Low-Damage (HSLD) program have clearly demonstrated that numerous finish-process performance benefits can be realized by grinding silicon nitride at high wheel speeds. A new, single-step, roughing-process capable of producing high-quality silicon nitride parts at high material removal rates while dramatically reducing finishing costs has been developed.

  11. Crack problems in cylindrical and spherical shells

    NASA Technical Reports Server (NTRS)

    Erdogan, F.

    1976-01-01

    Standard plate or shell theories were used as a starting point to study the fracture problems in thin-walled cylindrical and spherical shells, assuming that the plane of the crack is perpendicular to the surface of the sheet. Since recent studies have shown that local shell curvatures may have a rather considerable effect on the stress intensity factor, the crack problem was considered in conjunction with a shell rather than a plate theory. The material was assumed to be isotropic and homogeneous, so that approximate solutions may be obtained by approximating the local shell crack geometry with an ideal shell which has a solution, namely a spherical shell with a meridional crack, a cylindrical shell with a circumferential crack, or a cylindrical shell with an axial crack. A method of solution for the specially orthotropic shells containing a crack was described; symmetric and skew-symmetric problems are considered in cylindrical shells with an axial crack.

  12. Control of hydroxyapatite crystallinity by mechanical grinding method.

    PubMed

    Nakano, T; Tokumura, A; Umakoshi, Y; Imazato, S; Ehara, A; Ebisu, S

    2001-08-01

    Crystallinity of hydroxyapatite reflecting crystal size and crystal elastic strain was controlled by the mechanical grinding (MG) technique using a set of container and balls made of SUS304 stainless steel or agate. Variation in the crystallinity through MG was monitored by the XRD method and represented by the broadening of the diffraction peak. Effect of changes in crystallite size and strain on the crystallinity was also examined using the Hall-plot method. Crystallinity rapidly decreased with milling time. Significant crystallographic diffraction peaks disappeared and a broad diffraction around 2theta=32 degrees was observed after MG for 72 h. The broadening was dominantly due to an increase in crystal strain in addition to fine crystallite size. Contamination from the container and balls during MG was more suppressed using agate than SUS304 stainless steel. The recovery process of crystallinity during heating between 300 degrees C and 1200 degrees C was examined focusing on the decrease in residual elastic strain. Low crystallinity was maintained at annealing temperatures below 800 degrees C but lattice defects were recovered above 1000 degrees C. PMID:15348242

  13. View factors of cylindrical spiral surfaces

    NASA Astrophysics Data System (ADS)

    Lebedev, Vladimir A.; Solovjov, Vladimir P.

    2016-03-01

    Analytical expressions are presented for the view factors (radiative configuration factors) associated with the flat right cylindrical spiral surface. Such cylindrical spiral systems are widely applied as electrical resistance heating elements for lighting devices, electronic radio tubes, high-speed gas flow heaters, and other appliances used for scientific, industrial and domestic purposes. Derivation of the view factors is based on the invariant principles and the results presented in Lebedev (2000, 2003,1988) [1-3].

  14. Damage experiments in cylindrical geometry update

    SciTech Connect

    Kaul, Anne; Holtkamp, David; Rodriguez, George

    2009-01-01

    Using a cylindrical configuration to study spallation damage allows for a natural recollection of the damaged material under proper driving conditions. Previous experiments provided data about failure initiation in aluminum in a cylindrical geometry and the behavior of material recollected after damage from pressures in the damage initiation regime. The current series of experiments studied the behavior of material recollected after complete failure. Results from the current experiments will be presented.

  15. A Solid Core Heatpipe Reactor with Cylindrical Thermoelectric Converter Modules

    SciTech Connect

    Sayre, Edwin D.; Vaidyanathan, Sam

    2006-01-20

    A nuclear space power system that consists of a solid metal nuclear reactor core with heat pipes carrying energy to a cylindrical thermoelectric converter surrounding each of the heat pipes with a heat pipe radiator surrounding the thermoelectric converter is the most simple and reliable space power system. This means no single point of failure since each heat pipe and cylindrical converter is a separate power system and if one fails it will not affect the others. The heat pipe array in the solid core is designed so that if an isolated heat pipe or even two adjacent heat pipes fail, the remaining heat pipes will still transport the core heat without undue overheating of the uranium nitride fuel. The primary emphasis in this paper is on simplicity, reliability and fabricability of such a space nuclear power source. The core and heat pipes are made of Niobium 1% Zirconium alloy (Nb1Zr), with rhenium lined fuel tubes, bonded together by hot isostatic pressure (HIPing) and with sodium as the heat pipe working fluid, can be operated up to 1250K. The cylindrical thermoelectric converter is made by depositing the constituents of the converter around a Nb1%Zr tube and encasing it in a Nb 1% Zr alloy tube and HIPing the structure to get final bonding and to produce residual compressive stresses in all brittle materials in the converter. A radiator heat pipe filled with potassium that operates at 850K is bonded to the outside of the cylindrical converter for cooling. The solid core heat pipe and cylindrical converter are mated by welding during the final assembly. A solid core reactor with 150 heat pipes with a 0.650-inch (1.65 cm) ID and a 30-inch (76.2 cm) length with an output of 8 Watts per square inch as demonstrated by the SP100 PD2 cell tests will produce about 80 KW of electrical power. An advanced solid core reactor made with molybdenum 47% rhenium alloy, with lithium heat pipes and the PD2 theoretical output of 11 watts per square inch or advanced higher

  16. A Solid Core Heatpipe Reactor with Cylindrical Thermoelectric Converter Modules

    NASA Astrophysics Data System (ADS)

    Sayre, Edwin D.; Vaidyanathan, Sam

    2006-01-01

    A nuclear space power system that consists of a solid metal nuclear reactor core with heat pipes carrying energy to a cylindrical thermoelectric converter surrounding each of the heat pipes with a heat pipe radiator surrounding the thermoelectric converter is the most simple and reliable space power system. This means no single point of failure since each heat pipe and cylindrical converter is a separate power system and if one fails it will not affect the others. The heat pipe array in the solid core is designed so that if an isolated heat pipe or even two adjacent heat pipes fail, the remaining heat pipes will still transport the core heat without undue overheating of the uranium nitride fuel. The primary emphasis in this paper is on simplicity, reliability and fabricability of such a space nuclear power source. The core and heat pipes are made of Niobium 1% Zirconium alloy (Nb1Zr), with rhenium lined fuel tubes, bonded together by hot isostatic pressure, (HIPing) and with sodium as the heat pipe working fluid, can be operated up to 1250K. The cylindrical thermoelectric converter is made by depositing the constituents of the converter around a Nb1%Zr tube and encasing it in a Nb 1% Zr alloy tube and HIPing the structure to get final bonding and to produce residual compressive stresses in all brittle materials in the converter. A radiator heat pipe filled with potassium that operates at 850K is bonded to the outside of the cylindrical converter for cooling. The solid core heat pipe and cylindrical converter are mated by welding during the final assembly. A solid core reactor with 150 heat pipes with a 0.650-inch (1.65 cm) ID and a 30-inch (76.2 cm) length with an output of 8 Watts per square inch as demonstrated by the SP100 PD2 cell tests will produce about 80 KW of electrical power. An advanced solid core reactor made with molybdenum 47% rhenium alloy, with lithium heat pipes and the PD2 theoretical output of 11 watts per square inch or advanced higher

  17. Simulating flow and segregation of cylindrical particles

    NASA Astrophysics Data System (ADS)

    Zhao, Yongzhi; Umbanhowar, Paul B.; Lueptow, Richard M.

    2015-11-01

    Efficient and accurate simulation of cylindrical particles using discrete element method (DEM) is a challenge. Typical approaches to simulating cylindrical particle systems are based on the glued spheres method, which has low accuracy, or real shape models, which have high computational cost. In this work we utilize super-ellipsoids, which belong to super-quadrics, to model cylindrical particles in DEM simulations. Simulations of a single cylinder impacting a flat wall indicate that super-ellipsoids provide the same accuracy as real shape models and much better accuracy than the glued sphere method. Simulations of super-ellipsoid cylindrical particles in rotating tumblers result in nearly the same angle of repose as experiments and real shape simulations, demonstrating the accuracy of super-ellipsoid DEM simulations for multi-particle systems. The segregation of bidisperse cylindrical particles differing in length in a bounded heap was simulated by super-ellipsoid DEM, and the results are similar to the experiment. In spite of these advantages of using super-ellipsoid cylindrical particles, simulations of filling a box with particles indicate that the simulation times for super-ellipsoid cylinders is about an order of magnitude longer than that for the same number of spherical particles.

  18. Tunnel Point Cloud Filtering Method Based on Elliptic Cylindrical Model

    NASA Astrophysics Data System (ADS)

    Zhua, Ningning; Jiaa, Yonghong; Luo, Lun

    2016-06-01

    The large number of bolts and screws that attached to the subway shield ring plates, along with the great amount of accessories of metal stents and electrical equipments mounted on the tunnel walls, make the laser point cloud data include lots of non-tunnel section points (hereinafter referred to as non-points), therefore affecting the accuracy for modeling and deformation monitoring. This paper proposed a filtering method for the point cloud based on the elliptic cylindrical model. The original laser point cloud data was firstly projected onto a horizontal plane, and a searching algorithm was given to extract the edging points of both sides, which were used further to fit the tunnel central axis. Along the axis the point cloud was segmented regionally, and then fitted as smooth elliptic cylindrical surface by means of iteration. This processing enabled the automatic filtering of those inner wall non-points. Experiments of two groups showed coincident results, that the elliptic cylindrical model based method could effectively filter out the non-points, and meet the accuracy requirements for subway deformation monitoring. The method provides a new mode for the periodic monitoring of tunnel sections all-around deformation in subways routine operation and maintenance.

  19. Performance of a Low-Power Cylindrical Hall Thruster

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.; Markusic, Thomas E.; Stanojev, Boris J.; Dehoyos, Amado; Raitses, Yevgeny; Smirnov, Artem; Fisch, Nathaniel J.

    2007-01-01

    Recent mission studies have shown that a Hall thruster which operates at relatively constant thrust efficiency (45-55%) over a broad power range (300W - 3kW) is enabling for deep space science missions when compared with slate-of-the-art ion thrusters. While conventional (annular) Hall thrusters can operate at high thrust efficiency at kW power levels, it is difficult to construct one that operates over a broad power envelope down to 0 (100 W) while maintaining relatively high efficiency. In this note we report the measured performance (I(sub sp), thrust and efficiency) of a cylindrical Hall thruster operating at 0 (100 W) input power.

  20. The Dizzying Depths of the Cylindrical Mirror

    NASA Astrophysics Data System (ADS)

    DeWeerd, Alan J.; Hill, S. Eric

    2005-02-01

    A typical introduction to geometrical optics treats plane and spherical mirrors. At first glance, it may be surprising that texts seldom mention the cylindrical mirror, except for the occasional reference to use in fun houses and to viewing anamorphic art.1,2 However, even a cursory treatment reveals its complexity. Holzberlein used an extended object to qualitatively illustrate that images are produced both before and behind a concave cylindrical mirror.3 He also speculated on how this extreme astigmatism results in an observer's dizziness. By considering a simple point object, we make a more detailed analysis of the cylindrical mirror and the dizziness it induces. First, we illustrate how rays from a point object reflect to form not one point image but two line images. Next, we describe how an observer perceives a likeness of the object. Finally, we suggest how confusing depth cues induce dizziness. Although we focus on the concave cylindrical mirror, the discussion is easy to generalize to the convex cylindrical mirror.

  1. A new cylindrical drift chamber for the MEG II experiment

    NASA Astrophysics Data System (ADS)

    Baldini, A. M.; Baracchini, E.; Berretta, L.; Bianucci, S.; Cavoto, G.; Chiarello, G.; Chiri, C.; Cei, F.; Corvaglia, A.; Dussoni, S.; Fahrni, D.; Galli, L.; Grancagnolo, F.; Grassi, M.; Hofer, A.; Hildebrandt, M.; Ignatov, F.; Miccoli, A.; Nicolò, D.; Orsini, A.; Panareo, M.; Pepino, A.; Pinto, C.; Piredda, G.; Signorelli, G.; Raffaelli, F.; Recchia, L.; Renga, F.; Ripiccini, E.; Tassielli, G.; Tazzioli, A.; Tenchini, F.; Venturini, M.; Voena, C.; Zullo, A.

    2016-07-01

    A new cylindrical drift chamber is currently under construction for the MEG II experiment. The chamber is meant to track low momentum positrons from μ+ decays to search for μ+ →e+ γ events. The detector is segmented in very small drift cells, placed in stereo configuration and operated in a helium-isobutane gas mixture. The use of thin aluminium wires and light gas mixture set the total radiation length of the chamber to only 1.6 ×10-3X0 per track turn allowing for a momentum resolution of ~120 keV/c.

  2. Two-dimensional magnetohydrodynamic turbulence - Cylindrical, non-dissipative model

    NASA Technical Reports Server (NTRS)

    Montgomery, D.; Vahala, G.

    1979-01-01

    Incompressible magnetohydrodynamic turbulence is treated in the presence of cylindrical boundaries which are perfectly conducting and rigidly smooth. The model treated is non-dissipative and two-dimensional, the variation of all quantities in the axial direction being ignored. Equilibrium Gibbs ensemble predictions are explored assuming the constraint of constant axial current (appropriate to tokamak operation). No small-amplitude approximations are made. The expectation value of the turbulent kinetic energy is found to approach zero for the state of maximum mean-square vector potential to energy ratio. These are the only states for which large velocity fluctuations are not expected.

  3. A novel method of freeform surface grinding with a soft wheel based on industrial robots

    NASA Astrophysics Data System (ADS)

    Sha, Sheng-chun; Guo, Xiao-ling

    2011-08-01

    In order to meet the growing demand for high-quality images, optical elements of freeform surface are more and more applied to imaging system. However the fabrication of freeform surface optical elements is much more difficult than that of traditional spherical ones. Recent research on freeform surface manufacture often deals with precision machine tools which have limitations on dimensions and are always expensive. Little has been researched on industrial robots. In this paper, a new method of freeform surface grinding based on industrial robots was found. This method could be applied to both whole surface grinding as well as partial surface grinding. The diameter of lenses to be ground would not be restricted to the machine tool's size. In this method a high-speed-rotating soft wheel was used. The relation between removing amount and grinding time which could be called removing function was established and measured. The machining precision was achieved by means of controlling the grinding time instead of the machine tool or industrial robot itself. There are two main factors affecting the removing function: i).rotating speed of the soft wheel; ii).pressure between the wheel and the work piece. In this paper, two groups of experiments have been conducted. One is the removing function tested at constant rotating speed while under different pressure. The other is that tested under a certain pressure with variable speed. Tables and curves which can show the effect of speed and pressure on the removing efficiency have been obtained. Cause for inaccuracy between experiment data and calculated result according to the theory and the non-linearity in the curves was analyzed. Through these analyses the removing function could be concluded under certain condition including rotating speed and pressure. Finally several experiments were performed to verify the appropriateness of the removing function. It could also be concluded that this method was more efficient in comparison

  4. Laser diode assembly including a cylindrical lens

    DOEpatents

    Snyder, J.J.; Reichert, P.

    1992-01-14

    The present invention provides a diffraction limited, high numerical aperture (fast) cylindrical microlens. The method for making the microlens is adaptable to produce a cylindrical lens that has almost any shape on its optical surfaces. The cylindrical lens may have a shape, such as elliptical or hyperbolic, designed to transform some particular given input light distribution into some desired output light distribution. In the method, the desired shape is first formed in a glass preform. Then, the preform is heated to the minimum drawing temperature and a fiber is drawn from it. The cross-sectional shape of the fiber bears a direct relation to the shape of the preform from which it was drawn. During the drawing process, the surfaces become optically smooth due to fire polishing. 11 figs.

  5. Laser diode assembly including a cylindrical lens

    DOEpatents

    Snyder, James J.; Reichert, Patrick

    1992-01-01

    The present invention provides a diffraction limited, high numerical aperture (fast) cylindrical microlens. The method for making the microlens is adaptable to produce a cylindrical lens that has almost any shape on its optical surfaces. The cylindrical lens may have a shape, such as elliptical or hyperbolic, designed to transform some particular given input light distribution into some desired output light distribution. In the method, the desired shape is first formed in a glass preform. Then, the preform is heated to the minimum drawing temperature and a fiber is drawn from it. The cross-sectional shape of the fiber bears a direct relation to the shape of the preform from which it was drawn. During the drawing process, the surfaces become optically smooth due to fire polishing.

  6. Current pulse effects on cylindrical damage experiments

    SciTech Connect

    Kaul, Ann M; Rousculp, Christopher L

    2009-01-01

    A series of joint experiments between LANL and VNIIEF use a VNIIEF-designed helical generator to provide currents for driving a LANL-designed cylindrical spallation experimental load. Under proper driving conditions, a cylindrical configuration allows for a natural recollection of the damaged material. In addition, the damaged material is able to come to a complete stop due to its strength, avoiding application of further forces. Thus far, experiments have provided data about failure initiation of a well-characterized material (aluminum) in a cylindrical geometry, behavior of material recollected after damage from pressures in the damage initiation regime, and behavior of material recollected after complete failure. In addition to post-shot collection of the damaged target material for subsequent metallographic analysis, dynamic in-situ experimental diagnostics include velocimetry and transverse radial radiography. This paper will focus on the effects of tailoring the driving current pulse to obtain the desired data.

  7. Westinghouse Modular Grinding Process - Enhancement of Volume Reduction for Hot Resin Supercompaction - 13491

    SciTech Connect

    Fehrmann, Henning; Aign, Joerg

    2013-07-01

    In nuclear power plants (NPP) ion exchange (IX) resins are used in several systems for water treatment. Spent resins can contain a significant amount of contaminates which makes treatment for disposal of spent resins mandatory. Several treatment processes are available such as direct immobilization with technologies like cementation, bitumisation, polymer solidification or usage of a high integrity container (HIC). These technologies usually come with a significant increase in final waste volume. The Hot Resin Supercompaction (HRSC) is a thermal treatment process which reduces the resin waste volume significantly. For a mixture of powdered and bead resins the HRSC process has demonstrated a volume reduction of up to 75 % [1]. For bead resins only the HRSC process is challenging because the bead resins compaction properties are unfavorable. The bead resin material does not form a solid block after compaction and shows a high spring back effect. The volume reduction of bead resins is not as good as for the mixture described in [1]. The compaction properties of bead resin waste can be significantly improved by grinding the beads to powder. The grinding also eliminates the need for a powder additive.Westinghouse has developed a modular grinding process to grind the bead resin to powder. The developed process requires no circulation of resins and enables a selective adjustment of particle size and distribution to achieve optimal results in the HRSC or in any other following process. A special grinding tool setup is use to minimize maintenance and radiation exposure to personnel. (authors)

  8. [Grinding of titanium. 1. Commercial and experimental wheels made of silicon carbide abrasives].

    PubMed

    Miyakawa, O; Watanabe, K; Okawa, S; Nakano, S; Shiokawa, N; Kobayashi, M; Tamura, H

    1990-01-01

    Cast titanium was ground with commercial and experimental wheels made of silicon carbide abrasives, and their grinding performance was investigated. With the vitrified wheels made of the GC abrasive, at a higher the wheel circumferential speed and heavier the grinding pressure, the cutting rate was greater, accompanied by violent wear of the wheel. Being independent of the wheel speed, the grinding ratio reached about 1 under pressure heavier than 100 gf. The MgO-MgCl2-bonded wheels of the C abrasive exhibited a similar tendency. The manner in which the wheel was moved over the work during grinding proved to be very important, compared with the Ni-Cr alloy as reported previously. Only depression of the wheel against the work resulted in chemical attrition of the abrasive and discoloration of the work surface, or grinding burn, due to oxidation of titanium. Even when the wheel was moved over the work, chip-formation process of the cutting edge was far from ideal, and the work surface was contaminated due to reaction of titanium with the abrasive. At a higher wheel circumferential speed, more chips were loaded or built-up in the wheel and strongly rubbed the work surface, resulting in violent wear of the wheel; loading and dislodging of such chips were repeated. PMID:2134811

  9. Motor control of jaw movements: An fMRI study of parafunctional clench and grind behavior.

    PubMed

    Wong, Donald; Dzemidzic, Mario; Talavage, Thomas M; Romito, Laura M; Byrd, Kenneth E

    2011-04-01

    Jaw-clenching and tooth-grinding associated with bruxism can contribute to abnormal tooth wear and pain in the masticatory system. Clench and tooth-grinding jaw-movement tasks were evaluated in a block-design fMRI study comparing a dental-control (DC) group with a tooth-grinding (TG) group. Group classification was made prior to imaging based upon self-reported parafunctional clench and grind behavior and clinical evidence of abnormal tooth wear. Group differences in brain activation patterns were found for each task compared to the resting baseline. The DC group showed a more widely distributed pattern; more extensive activity in the supplementary motor area (SMA) proper that extended into the pre-SMA; and, for clench, activity in the left inferior parietal lobule (IPL). The DC group activated more than the TG subjects the left IPL for clench, and pre-SMA for grind. Neither task elicited more activity in the TG than DC subjects. Our group findings suggest that jaw-movement tasks executed by the TG group elicited (1) more efficient brain activation pattern consistent with other studies that found less extensive activity with executing "over-learned" tasks; (2) "underactive" SMA activity that underlies reduced motor planning; (3) decreased inferior parietal activity that is associated with lesser motor-attentional demands. Thus orofacial parafunctional habits may influence brain circuits recruited for jaw movements, providing a possible basis for understanding involuntary jaw movements in bruxism and oral movement disorders in general. PMID:21295015

  10. Economic analysis of a modified dry grind ethanol process with recycle of pretreated and enzymatically hydrolyzed distillers' grains.

    PubMed

    Perkis, David; Tyner, Wallace; Dale, Rhys

    2008-08-01

    A modification of the conventional dry grind process for producing ethanol from yellow dent corn is considered with respect to its economic value. Process modifications include recycling distillers' grains, after being pretreated and hydrolyzed, with the ground corn and water to go through fermentation again and increase ethanol yields from the corn starch. A dry grind financial model, which has been validated against other financial models in the industry, is utilized to determine the financial impact of the process changes. The hypothesis was that the enhanced process would yield higher revenues through additional ethanol sales, and higher valued dried distillers' grains (DDGS), due to its higher protein content, to mitigate the drop in DDGS yields. A 32% increase in net present value (NPV) for the overall operation is expected when applying the process modifications to a 100million gallon ethanol plant, and an enzyme cost of $0.20 for each additional gallon of ethanol produced. However, there may be no value added to the enhanced dried distillers' grains (eDDGS), even in light of its higher protein levels, as current pricing is expected to be more sensitive to the amino acid profile than the total protein level, and the eDDGS has lower lysine levels, a key amino acid. Thus, there is a decrease in revenue from eDDGS due to the combination of no price change and loss of DDGS yield to ethanol. The financial improvements are a result of the increased revenue from higher ethanol yields outpacing the sum of all added costs, which include higher capital costs, larger loan payments, increased operating costs, and decreased revenues from dried distillers' grains. PMID:18032032

  11. Light scattering from cylindrical structures on surfaces.

    PubMed

    Taubenblatt, M A

    1990-03-01

    Light scattering from a dielectric cylindrical structure on a surface by a plane wave with field vector along the cylinder axis is calculated with a modification of the coupled-dipole method. The interaction matrix is calculated with the use of both the direct contribution of a polarization current filament and its reflection from the surface. The reflected cylindrical waves are computed with the use of the Sommerfeld-type integral expression. Light scattering from structures of arbitrary cross section and the size of the order of a wavelength can be quickly determined with this method. PMID:19759774

  12. Self-referenced interferometer for cylindrical surfaces.

    PubMed

    Šarbort, Martin; Řeřucha, Šimon; Holá, Miroslava; Buchta, Zdeněk; Lazar, Josef

    2015-11-20

    We present a new interferometric method for shape measurement of hollow cylindrical tubes. We propose a simple and robust self-referenced interferometer where the reference and object waves are represented by the central and peripheral parts, respectively, of the conical wave generated by a single axicon lens. The interferogram detected by a digital camera is characterized by a closed-fringe pattern with a circular carrier. The interference phase is demodulated using spatial synchronous detection. The capabilities of the interferometer are experimentally tested for various hollow cylindrical tubes with lengths up to 600 mm. PMID:26836560

  13. Wheel wear and surface/subsurface qualities when precision grinding optical materials

    NASA Astrophysics Data System (ADS)

    Tonnellier, X.; Shore, P.; Luo, X.; Morantz, P.; Baldwin, A.; Evans, R.; Walker, D.

    2006-06-01

    An ultra precision large optics grinder, which will provide a rapid and economic solution for grinding large off-axis aspherical and free-form optical components, has been developed at Cranfield University. This paper presents representative grinding experiments performed on another machine - a 5 axes Edgetek - in order to verify the proposed BoX(r) grinding cycle. The optical materials assessed included; Zerodur(r), SIC and ULE(r), all three being materials are candidates for extreme large telescope (ELT) mirror segments. Investigated removal rates ranged from 2mm 3/s to 200mm 3/s. The higher removal rate ensures that a 1 metre size optic could be ground in less than 10 hours. These experiments point out the effect of diamond grit size on the surface quality and wheel wear. The power and forces for each material type at differing removal rates are presented, together with subsurface damage.

  14. Online monitoring of a belt grinding process by using a light scattering method

    SciTech Connect

    Boehm, Johannes; Vernes, Andras; Vorlaufer, Georg; Vellekoop, Michael

    2010-10-20

    Industrially ground surfaces often have a characteristic surface topography known as chatter marks. The surface finishing is mainly monitored by optical measurement techniques. In this work, the monitoring of an industrial belt grinding process with a light scattering sensor is presented. Although this technique is primarily applied for parametric surface roughness analysis, here it is shown that it enables also the measurement of the surface topography, i.e., the chatter marks occurring during the belt grinding process. In particular, it is proven that the light scattering method is appropriate to measure online the topography of chatter marks. Furthermore, the frequency analysis of the data reveals that the wavelength of chatter marks strongly depends on process parameters, such as the grinding speed.

  15. Fabrication of a grazing incidence telescope by grinding and polishing techniques on aluminum

    NASA Technical Reports Server (NTRS)

    Gallagher, Dennis; Cash, Webster; Green, James

    1991-01-01

    The paper describes the fabrication processes, by grinding and polishing, used in making the mirrors for a f/2.8 Wolter type-I grazing incidence telescope at Boulder (Colorado), together with testing procedure used to determine the quality of the images. All grinding and polishing is done on specially designed machine that consists of a horizontal spindle to hold and rotate the mirror and a stroke arm machine to push the various tools back and forth along the mirrors length. The progress is checked by means of the ronchi test during all grinding and polishing stages. Current measurements of the telescope's image quality give a FWHM measurement of 44 arcsec, with the goal set at 5-10 arcsec quality.

  16. Online monitoring of a belt grinding process by using a light scattering method.

    PubMed

    Böhm, Johannes; Vernes, Andras; Vorlaufer, Georg; Vellekoop, Michael

    2010-10-20

    Industrially ground surfaces often have a characteristic surface topography known as chatter marks. The surface finishing is mainly monitored by optical measurement techniques. In this work, the monitoring of an industrial belt grinding process with a light scattering sensor is presented. Although this technique is primarily applied for parametric surface roughness analysis, here it is shown that it enables also the measurement of the surface topography, i.e., the chatter marks occurring during the belt grinding process. In particular, it is proven that the light scattering method is appropriate to measure online the topography of chatter marks. Furthermore, the frequency analysis of the data reveals that the wavelength of chatter marks strongly depends on process parameters, such as the grinding speed. PMID:20962955

  17. Optical methods for cylindrical rough surface testing

    NASA Astrophysics Data System (ADS)

    Perez Quintian, F.; Rebollo, Maria A.; Gaggioli, Nestor G.; Raffo, C. A.

    1999-07-01

    This work studies theoretically the scattering of light from cylindrical rough surfaces. It is shown, for the conical diffraction configuration, that the mean intensity on an observation plane perpendicular to the cylinder longitudinal axis, is related to the statistical parameters that characterize the surface: the roughness (sigma) and the correlation length T.

  18. Distributed neural signals on parabolic cylindrical shells

    NASA Astrophysics Data System (ADS)

    Hu, S. D.; Li, H.; Tzou, H. S.

    2013-06-01

    Parabolic cylindrical shells are commonly used as key components in communication antennas, space telescopes, solar collectors, etc. This study focuses on distributed modal neural sensing signals on a flexible simply-supported parabolic cylindrical shell panel. The parabolic cylindrical shell is fully laminated with a piezoelectric layer on its outer surface and the piezoelectric layer is segmented into infinitesimal elements (neurons) to investigate the microscopic distributed neural sensing signals. Since the dominant vibration component of the shell is usually the transverse oscillation, a new transverse mode shape function is defined. Two shell cases, i.e., the ratio of the meridian height to the half span distance of a parabola at 1:4 (shallow) and 1:1 (deep), are studied to reveal the curvature effect to the neural sensing signals. Studies suggest that the membrane signal component dominates for lower natural modes and the bending signal component dominates for higher natural modes. The meridional membrane and bending signal components are mostly concentrated on the high-curvature areas, while the longitudinal bending component is mostly concentrated on the relatively flat areas. The concentration behavior becomes more prominent as the parabolic cylindrical shell deepens, primarily resulting from the enhanced membrane effect due to the increased curvature.

  19. Conformal cylindrically symmetric spacetimes in modified gravity

    NASA Astrophysics Data System (ADS)

    Türkog˜lu, Murat Metehan; Dog˜ru, Melis Ulu

    2015-11-01

    We investigate cylindrically symmetric spacetimes in the context of f(R) gravity. We firstly attain conformal symmetry of the cylindrically symmetric spacetime. We obtain solutions to use features of the conformal symmetry, field equations and their solutions for cylindrically symmetric spacetime filled with various cosmic matters such as vacuum state, perfect fluid, anisotropic fluid, massive scalar field and their combinations. With the vacuum state solutions, we show that source of the spacetime curvature is considered as Casimir effect. Casimir force for given spacetime is found using Wald’s axiomatic analysis. We expose that the Casimir force for Boulware, Hartle-Hawking and Unruh vacuum states could have attractive, repulsive and ineffective features. In the perfect fluid state, we show that matter form of the perfect fluid in given spacetime must only be dark energy. Also, we offer that potential of massive and massless scalar field are developed as an exact solution from the modified field equations. All solutions of field equations for vacuum case, perfect fluid and scalar field give a special f(R) function convenient to Λ-CDM model. In addition to these solutions, we introduce conformal cylindrical symmetric solutions in the cases of different f(R) models. Finally, geometrical and physical results of the solutions are discussed.

  20. Light Transmission Through Reflecting Cylindrical Tubes

    ERIC Educational Resources Information Center

    Cohen, D. K.; Potts, J. E.

    1978-01-01

    Describes an experiment in which a point source of light, when viewed through a cylindrical tube having reflecting inner walls, appears as a series of sharply defined rings, due to the multiple reflections from the inner walls of the tube. ( GA)

  1. Cylindrical Induction Melter Modicon Control System

    SciTech Connect

    Weeks, G.E.

    1998-04-01

    In the last several years an extensive R{ampersand}D program has been underway to develop a vitrification system to stabilize Americium (Am) and Curium (Cm) inventories at SRS. This report documents the Modicon control system designed for the 3 inch Cylindrical Induction Melter (CIM).

  2. Tamm plasmon polaritons in multilayered cylindrical structures

    NASA Astrophysics Data System (ADS)

    Little, C. E.; Anufriev, R.; Iorsh, I.; Kaliteevski, M. A.; Abram, R. A.; Brand, S.

    2012-12-01

    It is shown that cylindrical Bragg reflector structures with either a metal core, a metal cladding, or both can support Tamm plasmon polaritons (TPPs) that can propagate axially along the interface between the metallic layer and the adjacent dielectric. A transfer matrix formalism for cylindrical multilayered structures is used in association with cavity phase matching considerations to design structures that support Tamm plasmon polaritons at specified frequencies, and to explore the field distributions and the dispersion relations of the excitations. The cylindrical TPPs can exist in both the TE and TM polarizations for the special cases of modes with either azimuthal isotropy or zero axial propagation constant and also as hybrid cylindrical modes when neither of those conditions applies. In the cases considered the TPPs have low effective masses and low group velocities. Also, when there is both metallic core and cladding, near degenerate modes localized at each metallic interface can couple to produce symmetric and antisymmetric combinations whose frequency difference is in the terahertz regime.

  3. Ultrasound cylindrical phased array for transoesophageal thermal therapy: initial studies

    NASA Astrophysics Data System (ADS)

    Melodelima, David; Lafon, Cyril; Prat, Frederic; Birer, Alain; Cathignol, Dominique

    2002-12-01

    This work was undertaken to investigate the feasibility of constructing a cylindrical phased array composed of 64 elements spread around the periphery (OD 10.6 mm) for transoesophageal ultrasound thermotherapy. The underlying operating principle of this applicator is to rotate a plane ultrasound beam electronically. For this purpose, eight adjacent transducers were successively excited with appropriate delay times so as to generate a plane wave. The exposure direction was changed by exciting a different set of eight elements. For these feasibility studies, we used a cylindrical prototype (OD 10.6 mm) composed of 16 elementary transducers distributed over a quarter of the cylinder, all operating at 4.55 MHz. The active part was mechanically reinforced by a rigid damper structure behind the transducers. It was shown that an ultrasound field similar to that emitted by a plane transducer could be generated. Ex vivo experiments on pig's liver demonstrated that the ultrasound beam could be accurately rotated to generate sector-based lesions to a suitable depth (up to 19 mm). Throughout these experiments, exposures lasting 20 s were delivered at an acoustic intensity of 17 W cm-2. By varying the power from exposure to exposure, the depth of the lesion at different angles could be controlled.

  4. Research on Bamboo Charcoal Bonded Grinding Wheel and Its Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Li, Wei; Xu, Minjie; Zhan, Fangyong; Jin, Mingsheng

    2014-08-01

    In this paper, a new type of grinding wheel and its manufacturing production process are introduced. The new BCB (Bamboo Charcoal Bond) grinding wheel was made of bamboo charcoal, phenolic resin and abrasive powder with higher press and temperature. To investigate its mechanical features, such as Rockwell hardness, resistance to abrasion, and resistance to pressure, some experiments on three BCB samples with different Resin weight ratios 20%, 25%, 30%, were carried out. The results showed that the BCB sample with proper moulding process and Resin weight ratio had better performance.

  5. In Situ Investigation of a Self-Accelerated Cocrystal Formation by Grinding Pyrazinamide with Oxalic Acid.

    PubMed

    Kulla, Hannes; Greiser, Sebastian; Benemann, Sigrid; Rademann, Klaus; Emmerling, Franziska

    2016-01-01

    A new cocrystal of pyrazinamide with oxalic acid was prepared mechanochemically and characterized by PXRD, Raman spectroscopy, solid-state NMR spectroscopy, DTA-TG, and SEM. Based on powder X-ray diffraction data the structure was solved. The formation pathway of the reaction was studied in situ using combined synchrotron PXRD and Raman spectroscopy. Using oxalic acid dihydrate the initially neat grinding turned into a rapid self-accelerated liquid-assisted grinding process by the release of crystallization water. Under these conditions, the cocrystal was formed directly within two minutes. PMID:27428942

  6. Linac mechanic QA using a cylindrical phantom

    NASA Astrophysics Data System (ADS)

    Mamalui-Hunter, Maria; Li, Harold; Low, Daniel A.

    2008-09-01

    Precise mechanical operation of a linear accelerator (linac) is critical for accurate radiation therapy dose delivery. Quantitative procedures for linac mechanical quality assurance (QA) used in the standard of care are time consuming and therefore conducted on a relatively infrequent basis. We present a method for evaluating the mechanical performance of a linac based on a series of projection portal images of a prototype cylindrical phantom with embedded radiopaque fiducial markers. The marker autodetection process included modeling imager response to the radiation beam where the projected cylinder attenuation yielded a non-uniform image background. The linac mechanical characteristics were estimated based on nonlinear multi-objective optimization of the projected marker locations. The estimated geometry parameters for the tested commercial model were gantry angle deviation 0.075 ± 0.076° (1 SD), gantry sag 0.026 ± 0.02°, source-to-axis distance SAD 998.3 ± 1.7 mm, source-to-detector distance SDD 1493 ± 5.0 mm, couch vertical motion 0.6 ± 0.45 mm, couch rotation 0.154 ± 0.1° and average linac rotation center (1.02, -0.27, -0.37) ± (0.36,0.333,1.20) mm relative to the laser intersection. The imager shift was [-0.44, 2.6] ± [0.20, 1.1] mm and the imager orientation was in-plane rotation 0.05 ± 0.03°, roll -0.14 ± 0.09° and pitch -0.9 ± 0.604°. The performance of this procedure concerning marker detection and optimization was examined by comparing the detected set of marker coordinates to its back-calculated counterpart for three subgroups of markers: central, wall and intermediate relative to the center of the phantom. The maximum difference was less than 0.25 mm with a mean of 0.146 mm and a standard deviation of 0.07 mm. The clinical use of this automated procedure will allow more efficient, more thorough, and more frequent mechanical linac QA.

  7. Linac mechanic QA using a cylindrical phantom.

    PubMed

    Mamalui-Hunter, Maria; Li, Harold; Low, Daniel A

    2008-09-21

    Precise mechanical operation of a linear accelerator (linac) is critical for accurate radiation therapy dose delivery. Quantitative procedures for linac mechanical quality assurance (QA) used in the standard of care are time consuming and therefore conducted on a relatively infrequent basis. We present a method for evaluating the mechanical performance of a linac based on a series of projection portal images of a prototype cylindrical phantom with embedded radiopaque fiducial markers. The marker autodetection process included modeling imager response to the radiation beam where the projected cylinder attenuation yielded a non-uniform image background. The linac mechanical characteristics were estimated based on nonlinear multi-objective optimization of the projected marker locations. The estimated geometry parameters for the tested commercial model were gantry angle deviation 0.075 +/- 0.076 degrees (1 SD), gantry sag 0.026 +/- 0.02 degrees , source-to-axis distance SAD 998.3 +/- 1.7 mm, source-to-detector distance SDD 1493 +/- 5.0 mm, couch vertical motion 0.6 +/- 0.45 mm, couch rotation 0.154 +/- 0.1 degrees and average linac rotation center (1.02, -0.27, -0.37) +/- (0.36,0.333,1.20) mm relative to the laser intersection. The imager shift was [-0.44, 2.6] +/- [0.20, 1.1] mm and the imager orientation was in-plane rotation 0.05 +/- 0.03 degrees , roll -0.14 +/- 0.09 degrees and pitch -0.9 +/- 0.604 degrees . The performance of this procedure concerning marker detection and optimization was examined by comparing the detected set of marker coordinates to its back-calculated counterpart for three subgroups of markers: central, wall and intermediate relative to the center of the phantom. The maximum difference was less than 0.25 mm with a mean of 0.146 mm and a standard deviation of 0.07 mm. The clinical use of this automated procedure will allow more efficient, more thorough, and more frequent mechanical linac QA. PMID:18723927

  8. Viscoplastic analysis of an experimental cylindrical thrust chamber liner

    NASA Technical Reports Server (NTRS)

    Arya, Vinod K.; Arnold, Steven M.

    1991-01-01

    A viscoplastic stress-strain analysis of an experimental cylindrical thrust chamber is presented. A viscoelastic constitutive model incorporating a single internal state variable that represents kinematic hardening was employed to investigate whether such a viscoplastic model could predict the experimentally observed behavior of the thrust chamber. Two types of loading cycles were considered: a short cycle of 3.5 sec. duration that corresponded to the experiments, and an extended loading cycle of 485.1 sec. duration that is typical of the Space Shuttle Main Engine (SSME) operating cycle. The analysis qualitatively replicated the deformation behavior of the component as observed in experiments designed to simulate SSME operating conditions. The analysis also showed that the mode and location in the component may depend on the loading cycle. The results indicate that using viscoplastic models for structural analysis can lead to a more realistic life assessment of thrust chambers.

  9. Viscoplastic analysis of an experimental cylindrical thrust chamber liner

    NASA Technical Reports Server (NTRS)

    Arya, Vinod K.; Arnold, Steven M.

    1992-01-01

    A viscoplastic stress-strain analysis of an experimental cylindrical thrust chamber is presented. A viscoelastic constitutive model incorporating a single internal state variable that represents kinematic hardening was employed to investigate whether such a viscoplastic model could predict the experimentally observed behavior of the thrust chamber. Two types of loading cycles were considered: a short cycle of 3.5-s duration that corresponded to the experiments, and an extended loading cycle of 485.1 s duration that is typical of the Space Shuttle Main Engine (SSME) operating cycle. The analysis qualitatively replicated the deformation behavior of the component as observed in experiments designed to simulate SSME operating conditions. The analysis also showed that the mode and location of failure in the component may depend on the loading cycle. The results indicate that using viscoplastic models for structural analysis can lead to a more realistic life assessment of thrust chambers.

  10. Construction of a cylindrical brine test room using a tunnel boring machine

    SciTech Connect

    Likar, V.F.; Burrington, T.P.

    1990-01-01

    This paper discusses the construction of a horizontal cylindrical brine test room at the Waste Isolation Pilot Plant (WIPP). The room was constructed in the bedded salt formation at a depth of 655 meters with a tunnel boring machine. The machine leasing, technical and operational management, parameters involved, and successful completion of this effort are included. 3 figs.

  11. Cantor-type cylindrical-coordinate method for differential equations with local fractional derivatives

    NASA Astrophysics Data System (ADS)

    Yang, Xiao-Jun; Srivastava, H. M.; He, Ji-Huan; Baleanu, Dumitru

    2013-10-01

    In this Letter, we propose to use the Cantor-type cylindrical-coordinate method in order to investigate a family of local fractional differential operators on Cantor sets. Some testing examples are given to illustrate the capability of the proposed method for the heat-conduction equation on a Cantor set and the damped wave equation in fractal strings. It is seen to be a powerful tool to convert differential equations on Cantor sets from Cantorian-coordinate systems to Cantor-type cylindrical-coordinate systems.

  12. High speed cylindrical roller bearing analysis, SKF computer program CYBEAN. Volume 2: User's manual

    NASA Technical Reports Server (NTRS)

    Kleckner, R. J.; Pirvics, J.

    1978-01-01

    The CYBEAN (Cylindrical Bearing Analysis) was created to detail radially loaded, aligned and misaligned cylindrical roller bearing performance under a variety of operating conditions. Emphasis was placed on detailing the effects of high speed, preload and system thermal coupling. Roller tilt, skew, radial, circumferential and axial displacement as well as flange contact were considered. Variable housing and flexible out-of-round outer ring geometries, and both steady state and time transient temperature calculations were enabled. The complete range of elastohydrodynamic contact considerations, employing full and partial film conditions were treated in the computation of raceway and flange contacts. Input and output architectures containing guidelines for use and a sample execution are detailed.

  13. [Research on ultrafine grinding technology of improving dissolution rates of effective components in Sanjie Zhentong capsule].

    PubMed

    Xu, Zhong-kun; Gao, Jin; Qin, Jian-ping; Chen, Guang-bo; Wang, Zhen-zhong; Xiao, Wei

    2015-05-01

    The effects of ultrafine grinding on the dissolution rates of the effective components in Sanjie Zhentong capsule (SZC) were studied in this experiment. Fine and ultrafine powder of SZC intermediates were made by ordinary grinding and ultrafine grinding technology, and then granulated by wet granulation. SZC were prepared by fine powder, ultrafine powder and ultrafine granules, respectively. With resveratrol and loureirin B as investigated indexes, dissolution rates of the four intermediates in SZC were determined by cup method and HPLC. The dissolution rates of resveratrol in SZC prepared by fine powder, ultrafine powder and ultrafine granules were 26.11%, 63.27%, 67.49%, respectively; and the dissolution rates of loureirin B were 7.160%, 20.29%, 23.05%, respectively. The dissolution rate of resveratrol and loureirin B in SZC prepared by ultrafine granules was the best. D90 size of ultrafine grinding was 13.221 μm and could improve the dissolution rates of resveratrol and loureirin B in SZC. PMID:26390653

  14. Ductile grinding of silicon carbide as a production method for reflective optics

    SciTech Connect

    Kahl, W.K.

    1993-11-01

    Ductile regime grinding or shear-mode grinding is an enabling technology that is finding application in the optics manufacturing industry. By definition, ductile removal occurs when the scale of machining is conducted below a material-dependent critical dimension or chip size. Much of the interest in ductile grinding resides in manufacturing glass optics, which experience brittle-ductile transition at {approximately}10 nm. Silicon carbide has a critical dimension that is on the order of 100--200 nm, making it a more attractive candidate for the technology. Preliminary results from an on-axis chemical vapor deposited (CVD) SiC sphere (f/14) indicate 317 {Angstrom} surface roughness and 0.96 wave P-V figure were achieved with this manufacturing method. Surface finish, interferometric measured figure and BRDF scatter results are presented from ductile regime grinding of 40 and 75 mm flats of CVD silicon carbide, bare reaction bonded SiC (RBSiC) and uniaxial hot-pressed SiC (HPSiC).

  15. Effect of Superfine Grinding on Antidiabetic Activity of Bitter Melon Powder

    PubMed Central

    Zhu, Ying; Dong, Ying; Qian, Xiwen; Cui, Fengjie; Guo, Qin; Zhou, Xinghua; Wang, Yun; Zhang, Yi; Xiong, Zhiyu

    2012-01-01

    The antidiabetic activities of bitter melon powders produced with lyophilization/superfine grinding and hot air drying/normal grinding were investigated in vivo for selecting a suitable bitter melon processing procedure. After a five-week treatment, bitter melon lyophilized superfine grinding powder (BLSP) had a higher antidiabetic activity with reducing fasting blood glucose levels from 21.40 to 12.54 mmol/L, the serum insulin levels from 40.93 to 30.74 mIU/L, and restoring activities of SOD compared with those in the bitter melon hot air drying powder (BAP) treated group. Furthermore, BLSP protected pancreatic tissues including islet beta cells and reduced the loss of islet cells. Combined with the difference of compositions in BLSP and BAP, it could be concluded that superfine grinding and lyophilization processes were beneficial for presenting the antidiabetic activity, which will provide a reference for direct utilization of bitter melon as a suitable functional food to relieve symptoms of diabetes. PMID:23203059

  16. Comparison of alternative methods, sample grinds, and fermentation times for determining indigestible neutral detergent fiber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objectives of this study were to evaluate the effects of sample grind, fermentation method, and time on the determination of indigestible neutral detergent fiber (iNDF). Samples of: 1) alfalfa hay and silage, 2) corn stalks and silage, and 3) ryegrass and mixed grass hays were ground through 2-m...

  17. Why Do Marbles Become Paler on Grinding? Reflectance, Spectroscopy, Color, and Particle Size

    ERIC Educational Resources Information Center

    Lagorio, Maria Gabriela

    2004-01-01

    A qualitative description of the color-change problem, which will assist in rationalizing the change in color of marbles after grinding them using a simple physical picture and the qualitative dependence of diffuse reflectance on particle size is presented. Different approaches are discussed but it is seen that the interpretation of nanoparticles…

  18. 9. VIEW TO SOUTHSOUTHWEST, MINE WAREHOUSE, LABORATORY AND GRINDING/ROD MILL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. VIEW TO SOUTH-SOUTHWEST, MINE WAREHOUSE, LABORATORY AND GRINDING/ROD MILL (FOREGROUND), AND SAMPLING BUILDING AND WATER TOWER (BACKGROUND). - Vanadium Corporation of America (VCA) Naturita Mill, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

  19. Changes in mineral concentrations and phosphorus profile during dry-grind process of corn into ethanol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For determining variation in mineral composition and phosphorus (P) profile among streams of dry-grind ethanol production, samples of ground corn, intermediate streams, and distillers dried grains with solubles (DDGS) were obtained from 3 commercial plants. Most attributes (dry matter concentration...

  20. Composition of corn dry-grind ethanol by-products: DDGS, wet cake, and thin stillage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Distillers' Dried Grains with Solubles (DDGS) and wet distillers’ grains are the major co-products of the dry grind ethanol facilities. As they are mainly used as animal feed, a typical compositional analysis of the DDGS and wet distillers’ grains mainly focuses on defining the feedstock’s nutritio...

  1. Effects of Kernel Composition and Starch Structure on Ethanol Yield Produced from Dry-Grind Corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objectives of this study were to understand how the composition of kernels (i.e., starch, protein, and lipid contents) and the starch structure of dry-grind corn affected the enzyme hydrolysis of starch and the ethanol yield during yeast fermentation. Four lines of corn, designated, 05GEM06031, 06G...

  2. In-situ roundness measurement and correction for pin journals in oscillating grinding machines

    NASA Astrophysics Data System (ADS)

    Yu, Hongxiang; Xu, Mengchen; Zhao, Jie

    2015-01-01

    In the mass production of vehicle-engine crankshafts, pin chasing grinding using oscillating grinding machines is a widely accepted method to achieve flexible and efficient performance. However, the eccentric movement of pin journals makes it difficult to develop an in-process roundness measurement scheme for the improvement of contour precision. Here, a new in-situ roundness measurement strategy is proposed with high scanning speed. The measuring mechanism is composed of a V-block and an adaptive telescopic support. The swing pattern of the telescopic support and the V-block is analysed for an equal angle-interval signal sampling. Hence roundness error signal is extracted in frequency domain using a small-signal model of the V-block roundness measurement method and the Fast Fourier Transformation. To implement the roundness data in the CNC coordinate system of an oscillating grinding machine, a transformation function is derived according to the motion model of pin chasing grinding methodology. Computer simulation reveals the relationship between the rotational position of the crankshaft component and the scanning angle of the displacement probe on the V-block, as well as the influence introduced by the rotation centre drift. Prototype investigation indicates the validity of the theoretical analysis and the feasibility of the new strategy.

  3. Single Side Electrolytic In-Process Dressing (ELID) Grinding with Lapping Kinematics of Silicon Carbide

    NASA Astrophysics Data System (ADS)

    Khoshaim, Ahmed Bakr

    The demand for Silicon Carbide ceramics (SiC) has increased significantly in the last decade due to its reliable physical and chemical properties. The silicon carbide is widely used for aerospace segments in addition to many uses in the industry. Sometimes, a single side grinding is preferable than conventional grinding, for it has the ability to produce flat ceramics. However, the manufacturing cost is still high because of the high tool wear and long machining time. Part of the solution is to use electrolytic in process dressing (ELID) to reduce the processing time. The study on ELID single side grinding of ceramics has never been attempted before. The study involves four variables with three levels each. One of the variables, which is the eccentricity, is being investigated for the first time on ceramics. A full factorial design, for both the surface roughness and material removal rate, guides to calculate mathematical models that can predict future results. Three grinding wheel mesh sizes are used. An investigation of the influence of different grain size on the results can then be evaluated. The kinematics of the process was studied based on eccentricity in order to optimize the pattern of the diamond grains. The experiment is performed with the assist of the proposed specialized ELID fluid, TRIM C270E.

  4. APPLICATION OF HACCP TO CONTROL MYCOTOXINS IN THE DRY GRIND ETHANOL PROCESS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ethanol has been used as a fuel source in the United States since the early 1900’s and is receiving a renewed and increased interest as an alternative to petroleum. Today most fuel ethanol is produced by the dry grind mill process creating a valuable co-product, namely distillers dried grain with s...

  5. EFFECT OF LIMESTONE TYPE AND GRIND ON S02 SCRUBBER PERFORMANCE

    EPA Science Inventory

    The paper describes the effect of limestone type and grind on SO2 scrubber performance. It gives results of a comparison of the amount of limestone feed required as a function of particle size, to obtain a given SO2 removal efficiency and, thus, to verify the relative magnitude o...

  6. Manual of industrial diamonds plus dressing and grinding criteria for machining superalloys

    NASA Technical Reports Server (NTRS)

    Carr, W. L.

    1968-01-01

    Manual combines the important and controlling factors for the proper selection and use of diamond stones for cutting and dressing grinding wheels. This manual is a compilation of empirical data and incorporates an original companion treatise on the physical descriptions of the diamond stones, their grading, and their applications.

  7. Cryogenics and its application with reference to spice grinding: a review.

    PubMed

    Balasubramanian, S; Gupta, Manoj Kumar; Singh, K K

    2012-01-01

    Cryogenics is the study of very low temperature and its application on different materials including biological products. Cryogenics has numerous applications in space science, electronics, automobiles, the manufacturing industry, sports and musical instruments, biological science and agriculture, etc. Cryogenic freezing finds pivotal application in food, that is, spices and condiments. Although there is a wide range of cryogens to produce the desired low temperature, generally liquid nitrogen (LN₂) is used in food grinding. The application of low temperature shows a promising pathway to produce higher quality end product with higher flavor and volatile oil retention. Cryogenic grinders generally consist of precoolers and grinder with the cryogen distribution system. In such grinding systems, cryogens subject the raw material up to or lower than glass transition temperature before it is ground, thus eliminating much of the material and quality hassles of traditional grinding. At present, the capital investment including cryogen and handling costs escalate the final cost of the product. Thus, for large-scale production, a proper design to optimize and make it feasible is the need of the hour and understanding the behavior of different food materials at these low temperature conditions. This article reviews the scenario and application of cryogenics in different sectors, especially to spice grinding. PMID:22698269

  8. Grinding and cooking dry-mill germ to optimize aqueous enzymatic oil extraction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The many recent dry grind plants that convert corn to ethanol are potential sources of substantial amounts of corn oil. This report describes an aqueous enzymatic extraction (AEE) method to separate oil from dry-mill corn germ (DMG). The method is an extension of AEE previously developed for wet...

  9. Gravitational radiation from a cylindrical naked singularity

    SciTech Connect

    Nakao, Ken-ichi; Morisawa, Yoshiyuki

    2005-06-15

    We construct an approximate solution which describes the gravitational emission from a naked singularity formed by the gravitational collapse of a cylindrical thick shell composed of dust. The assumed situation is that the collapsing speed of the dust is very large. In this situation, the metric variables are obtained approximately by a kind of linear perturbation analysis in the background Morgan solution which describes the motion of cylindrical null dust. The most important problem in this study is what boundary conditions for metric and matter variables should be imposed at the naked singularity. We find a boundary condition that all the metric and matter variables are everywhere finite at least up to the first order approximation. This implies that the spacetime singularity formed by this high-speed dust collapse is very similar to that formed by the null dust and the final singularity will be a conical one. Weyl curvature is completely released from the collapsed dust.

  10. Quantum Cylindrical Waves and Parametrized Field Theory

    NASA Astrophysics Data System (ADS)

    Varadarajan, Madhavan

    In this article, we review some illustrative results in the study of two related toy models for quantum gravity, namely cylindrical waves (which are cylindrically symmetric gravitational fields)and parametrized field theory (which is just free scalar field theory on a flat space-time in generally covariant disguise). In the former, we focus on the phenomenon of unexpected large quantum gravity effects in regions of weak classical gravitational fields and on an analysis of causality in a quantum geometry. In the latter, we focus on Dirac quantization, argue that this is related to the unitary implementability of free scalar field evolution along curved foliations of the flat space-time and review the relevant results for unitary implementability.

  11. Nonaxisymmetric radiative transfer in cylindrical enclosures

    SciTech Connect

    Moder, J.P.; Lee, H.S.; Chai, J.C.; Parthasarathy, G.; Patankar, S.V.

    1996-12-31

    A finite-volume method for radiative transfer in cylindrical enclosures is presented. Angular redistribution terms in the equation of transfer are avoided by defining radiation directions in terms of angular coordinates measured with respect to Cartesian base vectors; this definition of radiation directions can result in control angles which overlap control-volume faces, depending on the type of spatial and angular grids used in the azimuthal direction. A simple treatment for such control-angle overlaps is presented which is also applicable to nonorthogonal curvilinear spatial-coordinates. A comparison of the present procedure with other similar methods is given. Solutions are presented for axisymmetric transfer through a cylinder and nonaxisymmetric transfer through two- and three-dimensional annular sectors. Results show that the procedure produces reasonable solutions for transparent and participating media in axisymmetric and nonaxisymmetric cylindrical enclosures.

  12. Surface superconductivity in thin cylindrical Bi nanowire.

    PubMed

    Tian, Mingliang; Wang, Jian; Ning, Wei; Mallouk, Thomas E; Chan, Moses H W

    2015-03-11

    The physical origin and the nature of superconductivity in nanostructured Bi remains puzzling. Here, we report transport measurements of individual cylindrical single-crystal Bi nanowires, 20 and 32 nm in diameter. In contrast to nonsuperconducting Bi nanoribbons with two flat surfaces, cylindrical Bi nanowires show superconductivity below 1.3 K. However, their superconducting critical magnetic fields decrease with their diameter, which is the opposite of the expected behavior for thin superconducting wires. Quasiperiodic oscillations of magnetoresistance were observed in perpendicular fields but were not seen in the parallel orientation. These results can be understood by a model of surface superconductivity with an enhanced surface-to-bulk volume in small diameter wires, where the superconductivity originates from the strained surface states of the nanowires due to the surface curvature-induced stress. PMID:25658139

  13. Damage experiments in a cylindrical geometry

    SciTech Connect

    Kaul, Ann M

    2010-09-21

    Studying spallation damage with a cylindrical configuration allows for a natural recollection of the damaged material under proper driving conditions. Additionally, the damaged material can come to a complete rest without the application of further stopping forces. Specific areas of research include the damage initiation regime in convergent geometry, behavior of material recollected after damage, and effects of convergent geometry on the material response. Such experiments produce unique strain and shear stress states, motivating improvements in existing computational material models and increasing the predictive capabilities of codes. A LANL/VNIIEF joint experimental series has produced cylindrical aluminum failure initiation data and studied the behavior of material recollected after damage initiation and after complete failure. In addition to post-shot collection of the damaged target material for subsequent metallographic analysis, dynamic in-situ experimental diagnostics include velocimetry and transverse radial radiography. This paper will discuss the current experimental status.

  14. Jamming of Cylindrical Grains in Vertical Channels

    NASA Astrophysics Data System (ADS)

    Baxter, G. William; Spier, Gregory; Barr, Nicholas; Steel, Fiona

    2012-02-01

    We study jamming of low aspect-ratio cylindrical Delrin grains in a vertical channel. These cylindrical grains resemble antacid tablets, poker chips, or coins since their height is less than their diameter. Grains are allowed to fall through a vertical channel with a square cross section where the channel width is greater than the diameter of a grain and constant throughout the length of the channel with no obstructions or constrictions. Within this channel, grains are sometimes observed to form jams, stable structures supported by the channel walls with no support beneath them. The probability of jam occurrence and the strength or robustness of a jam is effected by the grain dimensions and channel size. We will present experimental measurements of the jamming probability and jam strength in this system and discuss the relationship of these results to other experiments and theories.

  15. Multiple Bifurcations of a Cylindrical Dynamical System

    NASA Astrophysics Data System (ADS)

    Han, Ning; Cao, Qingjie

    2016-03-01

    This paper focuses on multiple bifurcations of a cylindrical dynamical system, which is evolved from a rotating pendulum with SD oscillator. The rotating pendulum system exhibits the coupling dynamics property of the bistable state and conventional pendulum with the ho- moclinic orbits of the first and second type. A double Andronov-Hopf bifurcation, two saddle-node bifurcations of periodic orbits and a pair of homoclinic bifurcations are detected by using analytical analysis and nu- merical calculation. It is found that the homoclinic orbits of the second type can bifurcate into a pair of rotational limit cycles, coexisting with the oscillating limit cycle. Additionally, the results obtained herein, are helpful to explore different types of limit cycles and the complex dynamic bifurcation of cylindrical dynamical system.

  16. Omnidirectional, circularly polarized, cylindrical microstrip antenna

    NASA Technical Reports Server (NTRS)

    Stanton, Philip H. (Inventor)

    1985-01-01

    A microstrip cylindrical antenna comprised of two concentric subelements on a ground cylinder, a vertically polarized (E-field parallel to the axis of the antenna cylinder) subelement on the inside and a horizontally polarized (E-field perpendicular to the axis) subelement on the outside. The vertical subelement is a wraparound microstrip radiator. A Y-shaped microstrip patch configuration is used for the horizontally polarized radiator that is wrapped 1.5 times to provide radiating edges on opposite sides of the cylindrical antenna for improved azimuthal pattern uniformity. When these subelements are so fed that their far fields are equal in amplitude and phased 90.degree. from each other, a circularly polarized EM wave results. By stacking a plurality of like antenna elements on the ground cylinder, a linear phased array antenna is provided that can be beam steered to the desired elevation angle.

  17. Buckling optimisation of sandwich cylindrical panels

    NASA Astrophysics Data System (ADS)

    Abouhamzeh, M.; Sadighi, M.

    2016-06-01

    In this paper, the buckling load optimisation is performed on sandwich cylindrical panels. A finite element program is developed in MATLAB to solve the governing differential equations of the global buckling of the structure. In order to find the optimal solution, the genetic algorithm Toolbox in MATLAB is implemented. Verifications are made for both the buckling finite element code and also the results from the genetic algorithm by comparisons to the results available in literature. Sandwich cylindrical panels are optimised for the buckling strength with isotropic or orthotropic cores with different boundary conditions. Results are presented in terms of stacking sequence of fibers in the face sheets and core to face sheet thickness ratio.

  18. Cylindrically converging blast waves in air

    NASA Astrophysics Data System (ADS)

    Matsuo, H.; Nakamura, Y.

    1981-07-01

    Cylindrically converging shock waves are produced by utilizing the detonation of cylindrical explosive shells. The production and the propagation of shock waves are observed by framing and streak camera photographs, and the trajectory of shock propagations is determined by using an electrical ionization probing system. The effect of the quantity of explosives on the stability, or the axial symmetry, of shock fronts and on the strength of shocks produced is investigated. It has been shown that, for practical purposes, the approximation of shock trajectories by Guderley's formulas would be sufficiently acceptable in an unexpectedly wide region near the implosion center, and that the axial symmetry of the shock front is improved by increasing the quantity of explosives, and thus, strong shocks are produced by merely increasing the quantity of explosives. The reflected diverging shock seems to be very stable. Piezoelectric elements have also been used to detect reflected diverging waves.

  19. Nanolaminate Membranes as Cylindrical Telescope Reflectors

    NASA Technical Reports Server (NTRS)

    Dooley, Jennifer; Dragovan, Mark; Hickey, Gregory; Lih, Shyh-Shiu Lih

    2010-01-01

    A document discusses a proposal to use axially stretched metal nanolaminate membranes as lightweight parabolic cylindrical reflectors in the Dual Anamorphic Reflector Telescope (DART) - a planned spaceborne telescope in which the cylindrical reflectors would be arranged to obtain a point focus. The discussion brings together a combination of concepts reported separately in several prior NASA Tech Briefs articles, the most relevant being "Nanolaminate Mirrors With Integral Figure-Control Actuators" NPO -30221, Vol. 26, No. 5 (May 2002), page 90; and "Reflectors Made From Membranes Stretched Between Beams" NPO -30571, Vol. 33, No. 10 (October 2009), page 11a. The engineering issues receiving the greatest emphasis in the instant document are (1) the change in curvature associated with the Poisson contraction of a stretched nanolaminate reflector membrane and (2) the feasibility of using patches of poly(vinylidene fluoride) on the rear membrane surface as piezoelectric actuators to correct the surface figure for the effect of Poisson contraction and other shape errors.

  20. Array gain for a cylindrical array with baffle scatter effects.

    PubMed

    Bertilone, Derek C; Killeen, Damien S; Bao, Chaoying

    2007-11-01

    Cylindrical arrays used in sonar for passive underwater surveillance often have sensors surrounding a cylindrical metal baffle. In some operational sonars, the phones in each stave (i.e., each line of phones aligned with the cylinder axis) are hardwired together so that the array is equivalent to a baffled circular array of directional elements, where each element corresponds to a line array of omnidirectional phones steered to broadside. In this paper a model is introduced for computing the array gain of such an array at high frequencies, which incorporates baffle scatter using infinite, rigid cylinder scattering theory, and with ambient noise described by an angular spectral density function. In practice the phones are often offset from the baffle surface, and the acoustic field sampled by the staves is distorted at high frequencies due to interference between the incident and scattered fields. Examples are given to illustrate the resulting array gain degradation, using three noise distributions that are frequently used in sonar performance modeling: three-dimensional isotropic, two-dimensional isotropic, and surface dipole noise. PMID:18189560

  1. Intense relativistic electron beam generation and prepulse effect in high power cylindrical diode

    SciTech Connect

    Roy, Amitava; Menon, R.; Mitra, S.; Kumar, D. D. P.; Kumar, Senthil; Sharma, Archana; Mittal, K. C.; Nagesh, K. V.; Chakravarthy, D. P.

    2008-01-01

    Intense gigawatt relativistic electron beam has been generated in a high power cylindrical diode in the presence of prepulse. A bipolar prepulse voltage, recorded at the diode, varies both in amplitude and time duration with the Marx generator voltage. It was found that only at the accelerating gap {<=}1.65 cm there is some shot to shot variation in the diode voltage and current for the same Marx generator voltage. The anode and cathode plasma expansion velocities were calculated using the perveance data. The plasma expands at 5 cm/{mu}s for 1.85 cm radial anode-cathode gap and the plasma velocity decreases for smaller gap. It was found that the effect of the prepulse is less pronounced in the cylindrical diode as compared to planar diode that allows one operation of the cylindrical diode with the gap {<=}1.85 cm.

  2. Domain wall dynamics in cylindrical nanomagnet

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Soumik; Singh, Amrita; Ghosh, Arindam

    2011-06-01

    The stochasticity associated with domain wall nucleation and propagation in a cylinderical nanowire has been studied using time resolved resistance measurement in presence of magnetic field. We have shown that the propagation stochasticity of domain wall in a cylindrical nanowire is reflected in the magnetic field dependent velocity distribution whereas the stochasticity involved in the domain wall nucleation can be effectively tuned by varying the angle between the direction of applied magnetic field and the long axis of the cylinder.

  3. Moiré effect in cylindrical objects

    NASA Astrophysics Data System (ADS)

    Saveljev, Vladimir

    2016-05-01

    The moiré effect in single-walled cylindrical objects (gridshells) is investigated. The surface of such an object is a rolled-up periodic grating (mesh). Analytical formulae are obtained for the period of the moiré patterns, which depends particularly on the direction of the wavevector of the grating. The experiments confirm the theory. The results can be applied to nanoparticles and to three-dimensional autostereoscopic displays.

  4. Numerical dynamo action in cylindrical containers

    NASA Astrophysics Data System (ADS)

    Nore, Caroline; Castanon Quiroz, Daniel; Guermond, Jean-Luc; Léorat, Jacques; Luddens, Francky

    2015-06-01

    The purpose of this paper is to present results from numerical simulations of dynamo action in relation with two magnetohydrodynamics (MHD) experiments using liquid sodium in cylindrical containers. The first one is the von Kármán sodium (VKS) experiment from Cadarache (France), the second one is a precession-driven dynamo experiment from the DREsden sodium facility for DYNamo and thermohydraulic studies (DRESDYN). Contribution to the topical issue "Electrical Engineering Symposium (SGE 2014) - Elected submissions", edited by Adel Razek

  5. Electronic quantum confinement in cylindrical potential well

    NASA Astrophysics Data System (ADS)

    Baltenkov, Arkadiy S.; Msezane, Alfred Z.

    2016-04-01

    The effects of quantum confinement on the momentum distribution of electrons confined within a cylindrical potential well have been analyzed. The motivation is to understand specific features of the momentum distribution of electrons when the electron behavior is completely controlled by the parameters of a non-isotropic potential cavity. It is shown that studying the solutions of the wave equation for an electron confined in a cylindrical potential well offers the possibility to analyze the confinement behavior of an electron executing one- or two-dimensional motion in the three-dimensional space within the framework of the same mathematical model. Some low-lying electronic states with different symmetries have been considered and the corresponding wave functions have been calculated; the behavior of their nodes and their peak positions with respect to the parameters of the cylindrical well has been analyzed. Additionally, the momentum distributions of electrons in these states have been calculated. The limiting cases of the ratio of the cylinder length H and its radius R0 have been considered; when the cylinder length H significantly exceeds its radius R0 and when the cylinder radius is much greater than its length. The cylindrical quantum confinement effects on the momentum distribution of electrons in these potential wells have been analyzed. The possible application of the results obtained here for the description of the general features in the behavior of electrons in nanowires with metallic type of conductivity (or nanotubes) and ultrathin epitaxial films (or graphene sheets) are discussed. Possible experiments are suggested where the quantum confinement can be manifested. Contribution to the Topical Issue "Atomic Cluster Collisions (7th International Symposium)", edited by Gerardo Delgado Barrio, Andrey Solov'Yov, Pablo Villarreal, Rita Prosmiti.

  6. Cylindrical multilayer metal-dielectric structures

    NASA Astrophysics Data System (ADS)

    Sasin, M. E.; Il'inskaya, N. D.; Zadiranov, Yu. M.; Kaliteevskaya, N. A.; Lazarenko, A. A.; Mazlin, V. A.; Brunkov, P. N.; Pavlov, S. I.; Kaliteevski, M. A.

    2015-11-01

    A method of creating a cylindrical structures consisting of thin metallic layer and dielectric multilayer Bragg reflector is described. Formation of the structures is observed experimentally as a result of separation and twisting away from the substrate a thin layer of gold coated with a multilayer SiO2/TiO2 Bragg reflector. It is suggested that such structures may be of interest for the creation of novel optoelectronic devices.

  7. Mach disc formation in cylindrical recovery systems

    SciTech Connect

    Morris, C.E.; McQueen, R.G.; Marsh, S.P.

    1983-01-01

    Cylindrical recovery systems have been used to shock-load polymers to pressures exceeding 50 GPa. In order to determine the pressures generated in these recovery systems the formation of the Mach disc on axis and its approach to steady state was monitored. The relation of the Mach disc diameter to the lateral dimension of the high explosive used to compress the polymer samples was also investigated.

  8. Combined illumination cylindrical millimeter-wave imaging technique for concealed weapon detection

    NASA Astrophysics Data System (ADS)

    Sheen, David M.; McMakin, Douglas L.; Hall, Thomas E.

    2000-07-01

    A novel millimeter-wave imaging technique has been developed for personnel surveillance applications, including the detection of concealed weapons, explosives, drugs, and other contraband material. Millimeter-waves are high-frequency radio waves in the frequency band of 30 - 300 GHz, and pose no health threat to humans at moderate power levels. These waves readily penetrate common clothing materials, and are reflected by the human body and by concealed items. The combined illumination cylindrical imaging concept consists of a vertical, high-resolution, millimeter-wave array of antennas which is scanned in a cylindrical manner about the person under surveillance. Using a computer, the data from this scan is mathematically reconstructed into a series of focused 3D images of the person. After reconstruction, the images are combined into a single high-resolution 3D image of the person under surveillance. This combined image is then rendered using 3D computer graphics techniques. The combined cylindrical illumination is critical as it allows the display of information from all angles. This is necessary because millimeter-waves do not penetrate the body. Ultimately, the images displayed to the operate will be icon-based to protect the privacy of the person being screened. Novel aspects of this technique include the cylindrical scanning concept and the image reconstruction algorithm, which was developed specifically for this imaging system. An engineering prototype based on this cylindrical imaging technique has been fabricated and tested. This work has been sponsored by the Federal Aviation Administration.

  9. Combined Illumination Cylindrical Millimeter-Wave Imaging Technique for Concealed Weapon Detection

    SciTech Connect

    Sheen, David M.; McMakin, Douglas L.; Hall, Thomas E.

    2000-04-01

    A novel millimeter-wave imaging technique has been developed for personnel surveillance applications, including the detection of concealed weapons, explosives, drugs, and other contraband material. Millimeter-waves are high-frequency radio waves in the frequency band of 30-300 GHz, and pose no health threat to humans at moderate power levels. These waves readily penetrate common clothing materials, and are reflected by the human body and by concealed items. The combined illumination cylindrical imaging concept consists of a vertical, high-resolution, millimeter-wave array of antennas which is scanned in a cylindrical manner about the person under surveillance. Using a computer, the data from this scan is mathematically reconstructed into a series of focused 3-D images of the person. After reconstruction, the images are combined into a single high-resolution three-dimensional image of the person under surveillance. This combined image is then rendered using 3-D computer graphics techniques. The combined cylindrical illumination is critical as it allows the display of information from all angles. This is necessary because millimeter-waves do not penetrate the body. Ultimately, the images displayed to the operator will be icon-based to protect the privacy of the person being screened. Novel aspects of this technique include the cylindrical scanning concept and the image reconstruction algorithm, which was developed specifically for this imaging system. An engineering prototype based on this cylindrical imaging technique has been fabricated and tested. This work has been sponsored by the Federal Aviation Administration (FAA).

  10. Influence of pin and hammer mill on grinding characteristics, thermal and antioxidant properties of coriander powder.

    PubMed

    Barnwal, P; Singh, K K; Sharma, Alka; Choudhary, A K; Saxena, S N

    2015-12-01

    In present study, influence of grinding (hammer and pin mills) and moisture content (range: 6.4-13.6 % dry basis) on the quality traits of coriander powder were investigated. These include grinding parameters, colour parameters, specific heat, thermal conductivity, thermal diffusivity, glass transition temperature, essential oil, total phenolic content, total flavonoid content and DPPH scavenging (%) of coriander powder. For coriander seed, the geometric properties such as major, medium, minor dimensions, geometric mean diameter, arithmetic mean diameter, sphericity, surface area and volume of coriander seeds increased significantly with increasing moisture (6.4-13.6 % db). For coriander powder, the grinding parameters such as average particle size, volume surface mean diameter and volume mean diameter increased significantly with increasing moisture (6.4-13.6 % db). With the grinding method, the colour attributes of coriander powder such as L-value, a-value, b-value, hue angle and browning index varied significantly. It was observed that the specific heat followed second order polynomial relationship with temperature and moisture whereas thermal conductivity varied linearly with temperature and moisture content. The variation of glass transition temperature with moisture can be best represented in quadratic manner. Total flavonoid content (mg QE/g crude seed extract) and DPPH scavenging % activity of coriander powder is significantly affected by grinding methods. A lower value of specific heat was observed for hammer ground coriander powder as compared to pin mill ground coriander powder. The thermal conductivity of hammer mill ground coriander powder was higher as compared to pin mill ground coriander. It was observed that hammer mill yields more fine coriander powder in comparison to pin mill. The browning index was more in hammer mill ground coriander powder. PMID:26604351

  11. Surface quality of a 1m Zerodur part using an effective grinding mode

    NASA Astrophysics Data System (ADS)

    Tonnellier, X.; Shore, P.; Morantz, P.; Orton, D.

    2008-09-01

    A new ultra precision large optics grinding machine, BoX (R) , has been developed at Cranfield University. This machine is located at the UK's Ultra Precision Surfaces laboratory at the OpTIC Technium, North Wales. This machine offers a rapid and economic solution for grinding large off-axis aspherical and free-form optical components. This paper presents an analysis of surface and subsurface damage assessments of Zerodur(R) ground using diamond resin bonded grinding wheels. Zerodur(R) was tested as it is one of the materials currently under study for making extremely large telescope (ELT) segmented mirrors such as in the E-ELT project. The grinding experiments have been conducted on the BoX(R) grinding machine using wheels with grit sizes of 76 μm, 46 µm and 25 μm. The highest material removal rate (187.5 mm3/s) used ensures that a 1 metre diameter optic can be ground in less than 10 hours. The surface roughness and surface profile were measured using a Form Talysurf. The subsurface damage was revealed using a sub aperture polishing process in combination with an etching technique on small parts. These results are compared with the targeted form accuracy of 1 μm p-v over a 1 metre part, surface roughness of 50-150 nm RMS and subsurface damage in the range of 2-5 μm. This process stage was validated on a 1 metre hexagonal Zerodur(R) part.

  12. Dissolution Behaviour of Hazardous Materials from Steel Slag with Wet Grinding Method

    NASA Astrophysics Data System (ADS)

    Hisyamudin Muhd Nor, Nik; Norhana Selamat, Siti; Hanif Abd Rashid, Muhammad; Fauzi Ahmad, Mohd; Jamian, Saifulnizan; Chee Kiong, Sia; Fahrul Hassan, Mohd; Mohamad, Fariza; Yokoyama, Seiji

    2016-06-01

    Steel slag is a by-product from steel industry and it contains variety of hazardous materials. In this study, the dissolution behaviour and removal potential of hazardous materials from steel slag with the wet grinding method was investigated. The slag was wet ground in the CO2 atmosphere and the slurry produced was filtered using centrifugal separator to separate the liquid and solid sediments. Then, the concentrations of dissolved metal elements in the liquid sediment were analyzed by ICP-MS. The changes of pH during the grinding were also investigated. It was found that the pHs were decreased immediately after the CO2 gas introduced into the vessel. The pHs were ranging from 6.8 to 7.6 at the end of grinding. The dissolved concentration of Zn and Cr were ranging from 5~45 [mg/dm3] and 0.2~2.5 [mg/dm3] respectively. The ratios of Zn removal for stainless steel oxidizing and reducing slag were very high, but those from normal steel oxidizing and reducing slag were very low. It is assumed that the Zn dissolved as ZnOH+ from Zn(OH)2 that formed due to the reaction between ZnO and water. Dissolution of Cr also occurred but in very low quantity compared to the dissolution of Zn. The dissolution of Cr occurred due to the grinding process and small amount of Cr(OH)3 was formed during the grinding. This small formation of Cr(OH)3 resulted to the low dissolved concentration of Cr in the form of Cr(OH)2+. According to the XRD analysis, the Cr mostly existed in the slags as Cr(IIl) in the form of MgCr2O4 and FeCr2O4.

  13. On-machine measurement of the grinding wheels' 3D surface topography using a laser displacement sensor

    NASA Astrophysics Data System (ADS)

    Pan, Yongcheng; Zhao, Qingliang; Guo, Bing

    2014-08-01

    A method of non-contact, on-machine measurement of three dimensional surface topography of grinding wheels' whole surface was developed in this paper, focusing on an electroplated coarse-grained diamond grinding wheel. The measuring system consists of a Keyence laser displacement sensor, a Keyence controller and a NI PCI-6132 data acquisition card. A resolution of 0.1μm in vertical direction and 8μm in horizontal direction could be achieved. After processing the data by LabVIEW and MATLAB, the 3D topography of the grinding wheel's whole surface could be reconstructed. When comparing the reconstructed 3D topography of the grinding wheel's marked area to its real topography captured by a high-depth-field optical digital microscope (HDF-ODM) and scanning electron microscope (SEM), they were very similar to each other, proving that this method is accurate and effective. By a subsequent data processing, the topography of every grain could be extracted and then the active grain number, the active grain volume and the active grain's bearing ration could be calculated. These three parameters could serve as the criterion to evaluate the grinding performance of coarse-grained diamond grinding wheels. Then the performance of the grinding wheel could be evaluated on-machine accurately and quantitatively.

  14. The grinding tip of the sea urchin tooth exhibits exquisite control over calcite crystal orientation and Mg distribution.

    PubMed

    Ma, Yurong; Aichmayer, Barbara; Paris, Oskar; Fratzl, Peter; Meibom, Anders; Metzler, Rebecca A; Politi, Yael; Addadi, Lia; Gilbert, P U P A; Weiner, Steve

    2009-04-14

    The sea urchin tooth is a remarkable grinding tool. Even though the tooth is composed almost entirely of calcite, it is used to grind holes into a rocky substrate itself often composed of calcite. Here, we use 3 complementary high-resolution tools to probe aspects of the structure of the grinding tip: X-ray photoelectron emission spectromicroscopy (X-PEEM), X-ray microdiffraction, and NanoSIMS. We confirm that the needles and plates are aligned and show here that even the high Mg polycrystalline matrix constituents are aligned with the other 2 structural elements when imaged at 20-nm resolution. Furthermore, we show that the entire tooth is composed of 2 cooriented polycrystalline blocks that differ in their orientations by only a few degrees. A unique feature of the grinding tip is that the structural elements from each coaligned block interdigitate. This interdigitation may influence the fracture process by creating a corrugated grinding surface. We also show that the overall Mg content of the tooth structural elements increases toward the grinding tip. This probably contributes to the increasing hardness of the tooth from the periphery to the tip. Clearly the formation of the tooth, and the tooth tip in particular, is amazingly well controlled. The improved understanding of these structural features could lead to the design of better mechanical grinding and cutting tools. PMID:19332795

  15. The grinding tip of the sea urchin tooth exhibits exquisite control over calcite crystal orientation and Mg distribution

    PubMed Central

    Ma, Yurong; Aichmayer, Barbara; Paris, Oskar; Fratzl, Peter; Meibom, Anders; Metzler, Rebecca A.; Politi, Yael; Addadi, Lia; Gilbert, P. U. P. A.; Weiner, Steve

    2009-01-01

    The sea urchin tooth is a remarkable grinding tool. Even though the tooth is composed almost entirely of calcite, it is used to grind holes into a rocky substrate itself often composed of calcite. Here, we use 3 complementary high-resolution tools to probe aspects of the structure of the grinding tip: X-ray photoelectron emission spectromicroscopy (X-PEEM), X-ray microdiffraction, and NanoSIMS. We confirm that the needles and plates are aligned and show here that even the high Mg polycrystalline matrix constituents are aligned with the other 2 structural elements when imaged at 20-nm resolution. Furthermore, we show that the entire tooth is composed of 2 cooriented polycrystalline blocks that differ in their orientations by only a few degrees. A unique feature of the grinding tip is that the structural elements from each coaligned block interdigitate. This interdigitation may influence the fracture process by creating a corrugated grinding surface. We also show that the overall Mg content of the tooth structural elements increases toward the grinding tip. This probably contributes to the increasing hardness of the tooth from the periphery to the tip. Clearly the formation of the tooth, and the tooth tip in particular, is amazingly well controlled. The improved understanding of these structural features could lead to the design of better mechanical grinding and cutting tools. PMID:19332795

  16. Grinding energy and physical properties of chopped and hammer-milled barley, wheat, oat, and canola straws

    SciTech Connect

    J.S. Tumuluru; L.G. Tabil; Y. Song; K.L. Iroba; V. Meda

    2014-01-01

    In the present study, specific energy for grinding and physical properties of wheat, canola, oat and barley straw grinds were investigated. The initial moisture content of the straw was about 0.13–0.15 (fraction total mass basis). Particle size reduction experiments were conducted in two stages: (1) a chopper without a screen, and (2) a hammer mill using three screen sizes (19.05, 25.4, and 31.75 mm). The lowest grinding energy (1.96 and 2.91 kWh t-1) was recorded for canola straw using a chopper and hammer mill with 19.05-mm screen size, whereas the highest (3.15 and 8.05 kWh t-1) was recorded for barley and oat straws. The physical properties (geometric mean particle diameter, bulk, tapped and particle density, and porosity) of the chopped and hammer-milled wheat, barley, canola, and oat straw grinds measured were in the range of 0.98–4.22 mm, 36–80 kg m-3, 49–119 kg m-3, 600–1220 kg m-3, and 0.9–0.96, respectively. The average mean particle diameter was highest for the chopped wheat straw (4.22-mm) and lowest for the canola grind (0.98-mm). The canola grinds produced using the hammer mill (19.05-mm screen size) had the highest bulk and tapped density of about 80 and 119 kg m-3; whereas, the wheat and oat grinds had the lowest of about 58 and 88–90 kg m-3. The results indicate that the bulk and tapped densities are inversely proportional to the particle size of the grinds. The flow properties of the grinds calculated are better for chopped straws compared to hammer milled using smaller screen size (19.05 mm).

  17. Cylindrical Wire Electrical Discharge Machining of Metal Bond Diamond Wheels- Part II: Wheel Wear Mechanism

    SciTech Connect

    McSpadden, SB

    2002-01-22

    The use of stereo scanning Electron Microscopy (SEM) to investigate the wear mechanism of the wire EDM true metal bond diamond wheel for ceramic grinding is presented. On the grinding wheel, a wedge-shape removal part was machined to enable the examination and measurement of the worn wheel surfaces using the stereo SEM. The stereo SEM was calibrated by comparing results of depth profile of a wear groove with the profilometer measurements. On the surface of the grinding wheel after wire EDM truing and before grinding, the diamond protruding heights were measured in the level of 35 {micro}m, comparing to the 54 {micro}m average size of the diamond in the grinding wheel. The gap between the EDM wire and rotating grinding wheel is estimated to be about 35 to 40 {micro}m. This observation indicates that, during the wire EDM, electrical sparks occur between the metal bond and EDM wire, which leaves the diamond protruding in the gap between the wire and wheel. The protruding diamond is immediately fractured at the start of the grinding process, even under a light grinding condition. After heavy grinding, the grinding wheel surface and the diamond protrusion heights are also investigated using the stereo SEM. The height of diamond protrusion was estimated in the 5 to 15 {micro}m range. This study has demonstrated the use of stereo SEM as a metrology tool to study the grinding wheel surface.

  18. Effectiveness of dust control methods for crystalline silica and respirable suspended particulate matter exposure during manual concrete surface grinding.

    PubMed

    Akbar-Khanzadeh, Farhang; Milz, Sheryl A; Wagner, Cynthia D; Bisesi, Michael S; Ames, April L; Khuder, Sadik; Susi, Pam; Akbar-Khanzadeh, Mahboubeh

    2010-12-01

    Concrete grinding exposes workers to unacceptable levels of crystalline silica dust, known to cause diseases such as silicosis and possibly lung cancer. This study examined the influence of major factors of exposure and effectiveness of existing dust control methods by simulating field concrete grinding in an enclosed workplace laboratory. Air was monitored during 201 concrete grinding sessions while using a variety of grinders, accessories, and existing dust control methods, including general ventilation (GV), local exhaust ventilation (LEV), and wet grinding. Task-specific geometric mean (GM) of respirable crystalline silica dust concentrations (mg/m³ for LEV:HEPA-, LEV:Shop-vac-, wet-, and uncontrolled-grinding, while GV was off/on, were 0.17/0.09, 0.57/0.13, 1.11/0.44, and 23.1/6.80, respectively. Silica dust concentrations (mg/m³ using 100-125 mm (4-5 inch) and 180 mm (7 inch) grinding cups were 0.53/0.22 and 2.43/0.56, respectively. GM concentrations of silica dust were significantly lower for (1) GV on (66.0%) vs. off, and (2) LEV:HEPA- (99.0%), LEV:Shop-vac- (98.1%) or wet- (94.4%) vs. uncontrolled-grinding. Task-specific GM of respirable suspended particulate matter (RSP) concentrations (mg/m³ for LEV:HEPA-, LEV:Shop-vac-, wet-, and uncontrolled grinding, while GV was off/on, were 1.58/0.63, 7.20/1.15, 9.52/4.13, and 152/47.8, respectively. GM concentrations of RSP using 100-125 mm and 180 mm grinding cups were 4.78/1.62 and 22.2/5.06, respectively. GM concentrations of RSP were significantly lower for (1) GV on (70.2%) vs. off, and (2) LEV:HEPA- (98.9%), LEV:Shop-vac- (96.9%) or wet- (92.6%) vs. uncontrolled grinding. Silica dust and RSP were not significantly affected by (1) orientation of grinding surfaces (vertical vs. inclined); (2) water flow rates for wet grinding; (3) length of task-specific sampling time; or, (4) among cup sizes of 100, 115 or 125 mm. No combination of factors or control methods reduced an 8-hr exposure level to below the

  19. Processing of cylindrical hollow parts: piercing vs. extrusion

    NASA Astrophysics Data System (ADS)

    Comăneci, R.; Zaharia, L.; Nedelcu, D.; Bujoreanu, L. G.

    2015-11-01

    As work principle, piercing (P) and backward extrusion (BE) are similar deforming processes. However, working-load, strain and material flow are quiet different depending on real conditions. Since punch diameter d and workpiece diameter D are the defining parameters for both P and BE, there is a critical d/D ratio separating them as distinctive operations. To have a complete description of P and BE in terms of working load and yield pressure as function of d/D ratio, experimental tests and numerical predictions were conducted. Tridimensional finite element analysis (FEA) for different process designs (i.e. different d/D ratios) revealed distinctive evolutions of the material flow establishing the effective limits of P and BE respectively. Experimental and numerical results can be used in practice to provide estimates of working-load, critical yield pressure and tool dimensions for optimal P and BE in processing of cylindrical hollow parts.

  20. High-speed velocimetry inside imploding cylindrical liners

    NASA Astrophysics Data System (ADS)

    Dolan, Daniel; Lemke, Ray; Dalton, Devon; Harding, Eric; McBride, Ryan; Martin, Matthew; Blue, Brent; Walker, Scott

    2014-03-01

    Dynamic planar compression is conceptually simple but difficult to maintain at extreme pressure (>5 Mbar). Higher pressures are attainable with imploding cylindrical liners, using Photonic Doppler velocimetry (PDV) to track the liner interior. PDV measures Doppler shift directly--1 GHz of beat frequency for every 1 km/s of velocity--requiring a special ``leapfrog'' approach for liners traveling in excess of 20 km/s. Single-point and multi-point PDV measurements have been performed in aluminum, beryllium, and tantalum liners under ramp compression, and the technique can readily applied to other implosion experiments. Combined with electrical current diagnostics, these measurements test thermodynamic equations of state at pressures up to 10 MBar and beyond. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85.

  1. Cylindrical nonlinear Schroedinger equation versus cylindrical Korteweg-de Vries equation

    SciTech Connect

    Fedele, Renato; De Nicola, Sergio; Grecu, Dan; Visinescu, Anca; Shukla, Padma K.

    2008-10-15

    A correspondence between the family of cylindrical nonlinear Schroedinger (cNLS) equations and the one of cylindrical Korteweg-de Vries (cKdV) equations is constructed. It associates non stationary solutions of the first family with the ones of the second family. This is done by using a correspondence, recently found, between the families of generalized NLS equation and generalized KdV equation, and their solutions in the form of travelling waves, respectively. In particular, non-stationary soliton-like solutions of the cNLS equation can be associated with non-stationary soliton-like solutions of cKdV equation.

  2. Motion parallax in immersive cylindrical display systems

    NASA Astrophysics Data System (ADS)

    Filliard, N.; Reymond, G.; Kemeny, A.; Berthoz, A.

    2012-03-01

    Motion parallax is a crucial visual cue produced by translations of the observer for the perception of depth and selfmotion. Therefore, tracking the observer viewpoint has become inevitable in immersive virtual (VR) reality systems (cylindrical screens, CAVE, head mounted displays) used e.g. in automotive industry (style reviews, architecture design, ergonomics studies) or in scientific studies of visual perception. The perception of a stable and rigid world requires that this visual cue be coherent with other extra-retinal (e.g. vestibular, kinesthetic) cues signaling ego-motion. Although world stability is never questioned in real world, rendering head coupled viewpoint in VR can lead to the perception of an illusory perception of unstable environments, unless a non-unity scale factor is applied on recorded head movements. Besides, cylindrical screens are usually used with static observers due to image distortions when rendering image for viewpoints different from a sweet spot. We developed a technique to compensate in real-time these non-linear visual distortions, in an industrial VR setup, based on a cylindrical screen projection system. Additionally, to evaluate the amount of discrepancies tolerated without perceptual distortions between visual and extraretinal cues, a "motion parallax gain" between the velocity of the observer's head and that of the virtual camera was introduced in this system. The influence of this artificial gain was measured on the gait stability of free-standing participants. Results indicate that, below unity, gains significantly alter postural control. Conversely, the influence of higher gains remains limited, suggesting a certain tolerance of observers to these conditions. Parallax gain amplification is therefore proposed as a possible solution to provide a wider exploration of space to users of immersive virtual reality systems.

  3. Radiation of sound from unflanged cylindrical ducts

    NASA Technical Reports Server (NTRS)

    Hartharan, S. L.; Bayliss, A.

    1983-01-01

    Calculations of sound radiated from unflanged cylindrical ducts are presented. The numerical simulation models the problem of an aero-engine inlet. The time dependent linearized Euler equations are solved from a state of rest until a harmonic solution is attained. A fourth order accurate finite difference scheme is used and solutions are obtained from a fully vectorized Cyber-203 computer program. Cases of both plane waves and spin modes are treated. Spin modes model the sound generated by a turbofan engine. Boundary conditions for both plane waves and spin modes are treated. Solutions obtained are compared with experiments conducted at NASA Langley Research Center.

  4. High convergence implosion symmetry in cylindrical hohlraums

    SciTech Connect

    Amendt, P A; Bradley, D K; Hammel, B A; Landen, O L; Suter, L J; Turner, R E; Wallace, R J

    1999-09-01

    High convergence, hohlraum-driven implosions will require control of time-integrated drive asymmetries to 1% levels for ignition to succeed on the NIF. We review how core imaging provides such asymmetry measurement accuracy for the lowest order asymmetry modes, and describe recent improvements in imaging techniques that should allow detection of higher order asymmetry modes. We also present a simple analytic model explaining how the sensitivity of symmetry control to beam pointing scales as we progress from single ring per side Nova cylindrical hohlraum illumination geometries to NIF-like multiple rings per side Omega hohlraum illumination geometries and ultimately to NIF-scale hohlraums.

  5. Liquid crystal alignment in cylindrical microcapillaries

    NASA Astrophysics Data System (ADS)

    Chychłowski, M.; Yaroshchuk, O.; Kravchuk, R.; Woliński, T.

    2011-09-01

    A variety of alignment configurations of liquid crystals (LCs) inside the glassy cylindrical capillaries is realized by using alignment materials providing different anchoring. The radial configuration with central disclination line is obtained for homeotropic boundary conditions. In turn, the axial, transversal and tilted alignment structures are realized by using materials for planar anchoring. The uniformity and controlling of the latter structures were provided by photoalignment method. This approach can be further used to control LC alignment in the photonic crystal fibers recognized as advanced elements for different optical devices.

  6. Liquid crystal alignment in cylindrical microcapillaries

    NASA Astrophysics Data System (ADS)

    Chychłowski, M.; Yaroshchuk, O.; Kravchuk, R.; Woliński, T.

    2012-03-01

    A variety of alignment configurations of liquid crystals (LCs) inside the glassy cylindrical capillaries is realized by using alignment materials providing different anchoring. The radial configuration with central disclination line is obtained for homeotropic boundary conditions. In turn, the axial, transversal and tilted alignment structures are realized by using materials for planar anchoring. The uniformity and controlling of the latter structures were provided by photoalignment method. This approach can be further used to control LC alignment in the photonic crystal fibers recognized as advanced elements for different optical devices.

  7. Grinding and polishing instead of sectioning for the tissue samples with a graft: Implications for light and electron microscopy.

    PubMed

    Mukhamadiyarov, Rinat A; Sevostyanova, Victoria V; Shishkova, Daria K; Nokhrin, Andrey V; Sidorova, Olga D; Kutikhin, Anton G

    2016-06-01

    A broad use of the graft replacement requires a detailed investigation of the host-graft interaction, including both histological examination and electron microscopy. A high quality sectioning of the host tissue with a graft seems to be complicated; in addition, it is difficult to examine the same tissue area by both of the mentioned microscopy techniques. To solve these problems, we developed a new technique of epoxy resin embedding with the further grinding, polishing, and staining. Graft-containing tissues prepared by grinding and polishing preserved their structure; however, sectioning frequently required the explantation of the graft and led to tissue disintegration. Moreover, stained samples prepared by grinding and polishing may then be assessed by both light microscopy and backscattered scanning electron microscopy. Therefore, grinding and polishing outperform sectioning when applied to the tissues with a graft. PMID:27023831

  8. The effect of bean origin and temperature on grinding roasted coffee

    NASA Astrophysics Data System (ADS)

    Uman, Erol; Colonna-Dashwood, Maxwell; Colonna-Dashwood, Lesley; Perger, Matthew; Klatt, Christian; Leighton, Stephen; Miller, Brian; Butler, Keith T.; Melot, Brent C.; Speirs, Rory W.; Hendon, Christopher H.

    2016-04-01

    Coffee is prepared by the extraction of a complex array of organic molecules from the roasted bean, which has been ground into fine particulates. The extraction depends on temperature, water chemistry and also the accessible surface area of the coffee. Here we investigate whether variations in the production processes of single origin coffee beans affects the particle size distribution upon grinding. We find that the particle size distribution is independent of the bean origin and processing method. Furthermore, we elucidate the influence of bean temperature on particle size distribution, concluding that grinding cold results in a narrower particle size distribution, and reduced mean particle size. We anticipate these results will influence the production of coffee industrially, as well as contribute to how we store and use coffee daily.

  9. The effect of bean origin and temperature on grinding roasted coffee

    PubMed Central

    Uman, Erol; Colonna-Dashwood, Maxwell; Colonna-Dashwood, Lesley; Perger, Matthew; Klatt, Christian; Leighton, Stephen; Miller, Brian; Butler, Keith T.; Melot, Brent C.; Speirs, Rory W.; Hendon, Christopher H.

    2016-01-01

    Coffee is prepared by the extraction of a complex array of organic molecules from the roasted bean, which has been ground into fine particulates. The extraction depends on temperature, water chemistry and also the accessible surface area of the coffee. Here we investigate whether variations in the production processes of single origin coffee beans affects the particle size distribution upon grinding. We find that the particle size distribution is independent of the bean origin and processing method. Furthermore, we elucidate the influence of bean temperature on particle size distribution, concluding that grinding cold results in a narrower particle size distribution, and reduced mean particle size. We anticipate these results will influence the production of coffee industrially, as well as contribute to how we store and use coffee daily. PMID:27086837

  10. The effect of bean origin and temperature on grinding roasted coffee.

    PubMed

    Uman, Erol; Colonna-Dashwood, Maxwell; Colonna-Dashwood, Lesley; Perger, Matthew; Klatt, Christian; Leighton, Stephen; Miller, Brian; Butler, Keith T; Melot, Brent C; Speirs, Rory W; Hendon, Christopher H

    2016-01-01

    Coffee is prepared by the extraction of a complex array of organic molecules from the roasted bean, which has been ground into fine particulates. The extraction depends on temperature, water chemistry and also the accessible surface area of the coffee. Here we investigate whether variations in the production processes of single origin coffee beans affects the particle size distribution upon grinding. We find that the particle size distribution is independent of the bean origin and processing method. Furthermore, we elucidate the influence of bean temperature on particle size distribution, concluding that grinding cold results in a narrower particle size distribution, and reduced mean particle size. We anticipate these results will influence the production of coffee industrially, as well as contribute to how we store and use coffee daily. PMID:27086837

  11. Clad vent set cup closure-weld-zone grinding evaluation

    SciTech Connect

    Ulrich, G.B.; Woods, A.T.; Ohriner, E.K.

    1996-04-01

    Clad vent set (CVS) cups were ground in the closure-weld zone to reduce the wall-thickness variation created by the cup deep-drawing process. A significantly more uniform wall thickness would be beneficial for the CVS closure-weld operation. The goal was to reduce the average within-cup wall-thickness variation (defined as the range of wall thicknesses in the closure-weld zone) approximately 50% from the Cassini production value of 42 {micro}m. This goal was shown to be achievable but, unfortunately, not with the existing blank and formed cup thicknesses.

  12. Determination of Cd and Pb in food slurries by GFAAS using cryogenic grinding for sample preparation.

    PubMed

    Santos, D; Barbosa, F; Tomazelli, A C; Krug, F J; Nóbrega, J A; Arruda, M A Z

    2002-06-01

    A simple method combining slurry sampling after cryogenic grinding and the use of a permanent modification of the integrated platform inside the transversely heated graphite atomizer (THGA) was proposed for the determination of Cd and Pb in foods. Potentialities of the cryogenic grinding were evaluated for grinding different materials of difficult homogenization such as high fat and high fiber tissues. Animal and vegetal samples were cut into small pieces and ground in liquid nitrogen for 2 min. Slurries were prepared directly in the autosampler cup after cryogenic grinding by transferring an exact amount of homogeneous powdered material (5-20 mg) to the cup, followed by 1.00 mL of 0.2% (v/v) HNO3 containing 0.04% (v/v) Triton X-100 and sonication for 30 s, before transferring into the platform previously coated with 250 microg W and 200 microg Rh. Use of a tungsten carbide-rhodium permanent modifier combined with NH4H2PO4 conventional modifier improves tube lifetime and increases the pyrolysis temperature for Cd. Homogeneity tests, carried out by comparing the between- and within-batch precision for each kind of sample, showed no significant differences at the 95% confidence level, indicating good homogeneity for 5-20 mg masses. Detection limits were 3.3 ng g(-1) Cd and 75 ng g(-1) Pb for 1% m/v slurries. Results for determination of Cd and Pb in foods slurries were in agreement with those obtained with digested samples, since no statistical differences were found by the paired t-test at the 95% level. PMID:12043022

  13. Analysis of surface integrity of grinded gears using Barkhausen noise analysis and x-ray diffraction

    SciTech Connect

    Vrkoslavová, Lucie; Louda, Petr; Malec, Jiři

    2014-02-18

    The contribution is focused to present results of study grinded gears made of 18CrNiMo7-6 steel used in the wind power plant for support (service) purposes. These gears were case-hardened due to standard hard case and soft core formation. This heat treatment increases wear resistance and fatigue strength of machine parts. During serial production some troubles with surface integrity have occurred. When solving complex problems lots of samples were prepared. For grinding of gears were used different parameters of cutting speed, number of material removal and lots from different subsuppliers. Material characterization was carried out using Barkhausen noise analysis (BNA) device; X-ray diffraction (XRD) measurement of surface residual stresses was done as well. Depth profile of measured characteristics, e.g. magnetoelastic parameter and residual stress was obtained by step by step layers' removing using electrolytic etching. BNA software Viewscan was used to measure magnetizing frequency sweep (MFS) and magnetizing voltage sweep (MVS). Scanning of Magnetoelastic parameter (MP) endwise individual teeth were also carried out with Viewscan. These measurements were done to find problematic surface areas after grinding such as thermal damaged locations. Plots of the hardness and thickness of case-hardened layer on cross sections were measurered as well. Evaluation of structure of subsurface case-hardened layer and core was made on etched metallographic patterns. The aim of performed measurements was to find correlation between conditions of grinding, residual stresses and structural and magnetoelastic parameters. Based on correlation of measured values and technological parameters optimizing the production of gears will be done.

  14. Analysis of surface integrity of grinded gears using Barkhausen noise analysis and x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Vrkoslavová, Lucie; Louda, Petr; Malec, Jiři

    2014-02-01

    The contribution is focused to present results of study grinded gears made of 18CrNiMo7-6 steel used in the wind power plant for support (service) purposes. These gears were case-hardened due to standard hard case and soft core formation. This heat treatment increases wear resistance and fatigue strength of machine parts. During serial production some troubles with surface integrity have occurred. When solving complex problems lots of samples were prepared. For grinding of gears were used different parameters of cutting speed, number of material removal and lots from different subsuppliers. Material characterization was carried out using Barkhausen noise analysis (BNA) device; X-ray diffraction (XRD) measurement of surface residual stresses was done as well. Depth profile of measured characteristics, e.g. magnetoelastic parameter and residual stress was obtained by step by step layers' removing using electrolytic etching. BNA software Viewscan was used to measure magnetizing frequency sweep (MFS) and magnetizing voltage sweep (MVS). Scanning of Magnetoelastic parameter (MP) endwise individual teeth were also carried out with Viewscan. These measurements were done to find problematic surface areas after grinding such as thermal damaged locations. Plots of the hardness and thickness of case-hardened layer on cross sections were measurered as well. Evaluation of structure of subsurface case-hardened layer and core was made on etched metallographic patterns. The aim of performed measurements was to find correlation between conditions of grinding, residual stresses and structural and magnetoelastic parameters. Based on correlation of measured values and technological parameters optimizing the production of gears will be done.

  15. OBSERVED BINARY FRACTION SETS LIMITS ON THE EXTENT OF COLLISIONAL GRINDING IN THE KUIPER BELT

    SciTech Connect

    Nesvorny, David; Vokrouhlicky, David; Bottke, William F.; Levison, Harold F.; Noll, Keith

    2011-05-15

    The size distribution in the cold classical Kuiper Belt (KB) can be approximated by two idealized power laws: one with steep slope for radii R > R* and one with shallow slope for R < R*, where R* {approx} 25-50 km. Previous works suggested that the size frequency distribution (SFD) rollover at R* can be the result of extensive collisional grinding in the KB that led to the catastrophic disruption of most bodies with R < R*. Here, we use a new code to test the effect of collisions in the KB. We find that the observed rollover could indeed be explained by collisional grinding provided that the initial mass in large bodies was much larger than the one in the present KB and was dynamically depleted. In addition to the size distribution changes, our code also tracks the effects of collisions on binary systems. We find that it is generally easier to dissolve wide binary systems, such as the ones existing in the cold KB today, than to catastrophically disrupt objects with R {approx} R*. Thus, the binary survival sets important limits on the extent of collisional grinding in the KB. We find that the extensive collisional grinding required to produce the SFD rollover at R* would imply a strong gradient of the binary fraction with R and separation, because it is generally easier to dissolve binaries with small components and/or those with wide orbits. The expected binary fraction for R {approx}< R* is {approx}<0.1. The present observational data do not show such a gradient. Instead, they suggest a large binary fraction of {approx}0.4 for R = 30-40 km. This may indicate that the rollover was not produced by disruptive collisions, but is instead a fossil remnant of the KB object formation process.

  16. Ultra fine grinding of low-rank coal. Progress report, April-June 1986

    SciTech Connect

    Bouchillon, C.W.; Steele, W.G.

    1986-07-01

    The lignite used for Phase I of the project was a Texas lignite from the Martin Lake mine obtained from the stockpile for the Martin Lake Power Plant of the Texas Utilities Generating Company. The power requirements for the fluid-energy mill were determined from the measured steam (or air) temperatures, pressures and pressure drops and the lignite flow rate. The instrument locations for the tests are shown on Figure 1. All of the instruments were connected to a microcomputer via an analog input interface board. Data were recorded on disks periodically throughout the tests. Appropriate calibration procedures were followed to assure that reliable data were being obtained. The combined grinding/drying tests were conducted in Vicksbuth, MS at Ergon, Inc.'s fluid-energy-mill facility. both steam and air were used as grinding fluids. With steam, tests were used as grinding fluids. With steam, tests were run with the following temperatures maintained inside the pulverizer: 310/sup 0/F, 350/sup 0/F, 400/sup 0/F, 488/sup 0/F. The materials from the grinding/drying tests have been analyzed. Tests included particle size distribution, density distribution, proximate and ultimate analyses, ash mineral analyses, electron microscope pictures, angle of repose and equilibrium moisture tests. These data have been correlated with the drying temperatures. The pulverized material was separated into different particle size groups with an air classifier. The samples from these tests were used to determine if one particle range had a higher ash content than the others. Very little difference in ash content was noted. Fluids at 1.2, 1.3, 1.4 and 1.6 specific gravities were used in a centrifuge to separate the ultrafine lignite into different density groups.

  17. Quantification of loosely associated and tightly associated bacteria on broiler carcass skin using swabbing, stomaching, and grinding methods.

    PubMed

    Singh, P; Lee, H C; Chin, K B; Ha, S D; Kang, I

    2015-12-01

    This research was conducted to quantify bacterial populations after swabbing or stomaching, followed by grinding the swabbed or stomached broiler skins. For each of 3 replications, 3 eviscerated broilers were randomly taken from a processing line in a local broiler processing plant. Ten swabs and 10 stomachs per bird were conducted on the left- and the right-side skins (10×7 cm), respectively, which were then finally ground. Results indicated that mesophilic aerobic bacteria (MAB) in the first swabbed sample were significantly lower than those in the first stomached sample (P<0.05), with no difference seen for the remaining sampling times (P>0.05). During 10 swabbings followed by final grinding, 8, 9, and 83% of MAB were detected after the first swabbing, after the second through 10th swabbings, and after final grinding of the skin, respectively. During 10 stomachings followed by the final grinding, 17, 18, and 65% of MAB were detected after the first stomaching, after the second through 10th stomachings, and after final grinding of the skin, respectively. Escherichia coli (E. coli) and coliforms were significantly higher in the first stomaching than those in the first swabbing (P<0.05), with no difference seen between the 2 sampling methods for the rest sampling times (P>0.05). Populations of E. coli and coliforms decreased step-wisely from the highest after grinding to the intermediate after first and second sampling, and to the least after 10th sampling (P<0.05), regardless of swabbing or grinding. In this study, less than 35% of MAB seemed loosely associated in the skin of eviscerated broiler, whereas more than 65% of MAB looked tightly associated, which were not recovered by stomaching or swabbing even 10 times but were recovered by grinding the skin. PMID:26467007

  18. Optical inspection system for cylindrical objects

    DOEpatents

    Brenden, Byron B.; Peters, Timothy J.

    1989-01-01

    In the inspection of cylindrical objects, particularly O-rings, the object is translated through a field of view and a linear light trace is projected on its surface. An image of the light trace is projected on a mask, which has a size and shape corresponding to the size and shape which the image would have if the surface of the object were perfect. If there is a defect, light will pass the mask and be sensed by a detector positioned behind the mask. Preferably, two masks and associated detectors are used, one mask being convex to pass light when the light trace falls on a projection from the surface and the other concave, to pass light when the light trace falls on a depression in the surface. The light trace may be either dynamic, formed by a scanned laser beam, or static, formed by such a beam focussed by a cylindrical lens. Means are provided to automatically keep the illuminating receiving systems properly aligned.

  19. Data fusion for cylindrical form measurements

    NASA Astrophysics Data System (ADS)

    Liu, Pei; Jusko, Otto; Tutsch, Rainer

    2015-12-01

    For high-precision form measurements of cylindrical workpieces form profiles such as roundness and straightness profiles are independently acquired via a bird-cage strategy. The 3D point cloud reconstructed by fusing these intersected profiles is meaningful in dimension and form assessment for cylinder, since enhanced accuracy can be achieved by fusion results. Moreover, it plays an important role as the input to other calculations. However, these data cannot be accurately aligned in form reconstruction, due to random absolute offsets in profiles and a lack of absolute positions. Therefore, we propose an approach to data fusion of these profiles to reconstruct cylindrical form. The uncertainties of the fused profile are evaluated, taking an individual contribution of a single profile and a global contribution of all profiles into account. The associated uncertainties are propagated using the Monte Carlo method. Experimental study results indicate that the data fusion procedure improves the accuracy of available datasets. After fusion, all available data points are capable of being used in the form assessment.

  20. Electron Confinement in Cylindrical Potential Well

    NASA Astrophysics Data System (ADS)

    Baltenkov, A. S.; Msezane, A. Z.

    2016-05-01

    We show that studying the solutions of the wave equation for an electron confined in a cylindrical potential well offers the possibility to analyze the confinement behavior of an electron executing one- or two-dimensional motion in the remaining three-dimensional space within the framework of the same mathematical model of the potential well. Some low-lying electronic states with different symmetries are considered and the corresponding wave functions are calculated. The behavior of their nodes and their peak positions with respect to the parameters of the cylindrical well is analyzed. Additionally, the momentum distributions of electrons in these states are calculated. The limiting cases of the ratio of the cylinder length H to its radius R0 are considered; when H significantly exceeds R0 and when R0 is much greater than H. The possible application of the results obtained here for the description of the general features in the behavior of electrons in nanowires with metallic type of conductivity (or nanotubes) and ultrathin epitaxial films (or graphene sheets) are discussed. Possible experiments are suggested as well where the quantum confinement can be manifested. Work supported by the Uzbek Foundation (ASB) and by the U.S. DOE, Division of Chemical Sciences, Geosciences and Biosciences, Office of Basic Energy Sciences, Office of Energy Research (AZM).

  1. Statistics properties of a cylindrical vector partially coherent beam.

    PubMed

    Dong, Yiming; Cai, Yangjian; Zhao, Chengliang; Yao, Min

    2011-03-28

    Cylindrical vector partially coherent beam is introduced as a natural extension of cylindrical vector coherent beam based on the unified theory of coherence and polarization. Analytical propagation formula for the cross-spectral density matrix of a cylindrical vector partially coherent beam passing through paraxial ABCD optical system is derived based on the generalized Collins integral formula. As an application example, the statistics properties, such as the average intensity, spreading and the degree of polarization, of a cylindrical vector partially coherent beam propagating in free space are studied in detail. It is found that the statistics properties of a cylindrical vector partially coherent beam are much different from a cylindrical vector coherent beam. Our results may find applications in connection with laser beam shaping and optical trapping. PMID:21451623

  2. Ultra-precision grinding of chemically vapor deposited silicon carbide mirrors for synchrotron radiation

    SciTech Connect

    Namba, Yoshiharu

    1996-12-31

    Chemically vapor deposited silicon carbide (CVD-SiC) is the most important material of mirrors for high-brightness synchrotron radiation beamlines, though the material is too difficult to be machined. It takes quite a long time to polish SiC substrate to make mirrors. This paper intends to reduce the machining time to make CVD-SiC mirrors by using ultra-precision grinding technology. The CVD-SiC sample has been ground into 0.4nm rms in surface roughness by a resinoid-bonded diamond wheel and an ultra-precision surface grinder having a glass-ceramic spindle of extremely-low thermal expansion. The surface roughness of ground samples were measured with TOPO-3D and AFM. 88.7% reflectivity has been obtained on the ground CVD-SiC flat surface, measured with X-ray of 0.834 nm in wavelength at the grazing incident angle of 0.7--0.95 degree. The reflectivity depends upon the angle between the direction of incident beam and grinding marks on the sample. The relationship between the surface roughness and grinding conditions was also discussed.

  3. A modeling and simulation procedure for grinding wheels in the presence of viscoelastic damping materials

    SciTech Connect

    Ahmadi, A.R.; Surana, K.S.; Norland, R.S.; Asmelash, Z.

    1998-12-31

    This paper presents a numerical simulation procedure for dynamic response analysis of industrial grinders containing viscoelastic components that contribute significant amount of damping to the total system response. The approach presented in this paper consists of: (a) obtaining undamped modal characteristics of the structure, (b) expressing the normal and tangential dynamic loads applied to each grinding segment through Fourier series, (c) transforming equations of motion including the real and imaginary parts of stiffness matrices (arising from the complex Young`s modulus) to undamped modal coordinate system, (d) decoupling of the modal equations of motion by transforming them into the damped modal coordinate system, and (e) computation of steady state response in the final coordinate system and transformation of the solution into the original structural coordinate system. This procedure is used to study the effects of structural damping (due to a viscoelastic layer of material present in the system) on dynamic the response due to periodic pulses of load acting on the grinding segments caused by grinding action.

  4. Precision grinding of tungsten carbide mold insert for molding of sub-millimeter glass aspheric lenses

    NASA Astrophysics Data System (ADS)

    Chao, Choung-Lii; Chang, Chia-Jung; Chen, Chun-Chieh; Chou, Wen-Chen; Ma, Kung-Jeng

    2013-06-01

    As the demand for precision optical components with sub-millimeter feature size steadily increasing, numerous efforts have been made in developing new techniques and in improving the existing approaches to efficiently and economically produce those components. Glass molding process (GMP) is one of these methods to enable mass production of precision glass optical components in recent years. One of the key issues in GMP is precision mold insert fabrication. Since the mould are normally made of hard and brittle materials such as tungsten carbide (WC) and silicon carbide (SiC), precision diamond grinding is by far the principal choice used to machine the GMP mould. As the feature size of optical component gets smaller, the size of mould and grinding wheel used to fabricate the mould gets smaller too. This makes the grinding process a very time consuming and expensive task. This research aimed to improve the small mold fabrication processes by developing an effective way of producing small diamond wheels and in-process monitoring wheel profile. Diamond wheels of around 0.2mm to 0.5mm in diameter after truing and WC aspheric mold insert of form accuracy around 0.47μm were successfully produced in this research.

  5. The efficacy of local exhaust ventilation for controlling dust exposures during concrete surface grinding.

    PubMed

    Croteau, Gerry A; Flanagan, Mary Ellen; Camp, Janice E; Seixas, Noah S

    2004-08-01

    This study assessed the effectiveness of a commercially available local exhaust ventilation (LEV) system for controlling respirable dust and crystalline silica exposures during concrete grinding activities. Surface grinding was conducted at six commercial building construction sites in Seattle, WA, by cement masons. Time-integrated filter samples and direct reading respirable dust concentrations were collected using a cyclone in line with a direct reading respirable dust monitor. Personal exposure levels were determined with and without LEV, one sample directly after the other. A total of 28 paired samples were collected in which three different dust collection shroud configurations were tested. Data obtained with a direct reading respirable dust monitor were adjusted to remove non-work task-associated dust exposures and was subsequently used to calculate the exposure reduction achieved. The application of LEV resulted in a reduction in the overall geometric mean respirable dust exposure from 4.5 to 0.14 mg/m(3), a mean exposure reduction of 92%. Despite the effective control of dust generated during surface grinding, 22 and 26% of the samples collected while LEV was being used were greater than the 8 h time-weighted average permissible exposure limit (Occupational Safety and Health Administration) and threshold limit value (American Congress of Governmental Industrial Hygienists) for respirable crystalline silica, respectively. PMID:15298850

  6. Electrolytic In-process Dressing (ELID) for high-efficiency, precision grinding of ceramic parts: An experiment study

    SciTech Connect

    Bandyopadhyay, B.P.

    1995-08-01

    This report describes Electrolytic In-process Dressing (ELID) as applied to the efficient, high-precision grinding of structural ceramics, and describes work performed jointly by Dr. B.P. Bandyopadhyay, University of North Dakota, and Dr. R. Ohmori, of the Institute of Physical and Chemical Research (RINEN), Tokyo, Japan, from June through August, 1994. Dr. Ohmori pioneered the novel ELID grinding technology which incorporates electrolytically enhanced, in-process dressing of metal bonded superabrasive wheels. The principle of ELID grinding technology is discussed in the report as will its application for rough grinding and precision grinding. Two types of silicon nitride based ceramics (Kyocerals Si{sub 3}N{sub 4}, and Eaton`s SRBSN) were ground under various conditions with ELID methods. Mirror surface finishes were obtained with {number_sign} 4000 mesh size wheel (average grain size = 4 {mu}m). Results of these investigations are presented in this report. These include the effects of wheel bond type, type of power supply, abrasive grit friability, and cooling fluid composition. The effects of various parameters are discussed in terms of the mechanisms of ELID grinding, and in particular, the manner of boundary layer formation on the wheels and abrasive grit protrusion.

  7. Note: Electrochemical etching of cylindrical nanoprobes using a vibrating electrolyte

    SciTech Connect

    Wang, Yufeng; Zeng, Yongbin Qu, Ningsong; Zhu, Di

    2015-07-15

    An electrochemical etching process using a vibrating electrolyte of potassium hydroxide to prepare tungsten cylindrical nanotips is developed. The vibrating electrolyte eases the effects of a diffusion layer and extends the etching area, which aid in the production of cylindrical nanotips. Larger amplitudes and a vibration frequency of 35 Hz are recommended for producing cylindrical nanotips. Nanotips with a tip radius of approximately 43 nm and a conical angle of arctan 0.0216 are obtained.

  8. Cylindrical Asymmetrical Capacitors for Use in Outer Space

    NASA Technical Reports Server (NTRS)

    Campbell, Jonathan W.

    2007-01-01

    A report proposes that cylindrical asymmetrical capacitors (CACs) be used to generate small thrusts for precise maneuvering of spacecraft on long missions. The report notes that it has been known for decades that when high voltages are applied to CACs in air, thrusts are generated - most likely as a result of ionization of air molecules and acceleration of the ions by the high electric fields. The report goes on to discuss how to optimize the designs of CACs for operation as thrusters in outer space. Components that could be used to enable outerspace operation include a supply of gas and a shroud, partly surrounding a CAC, into which the gas would flow. Other elements of operation and design discussed in the report include variation of applied voltage and/or of gas flow to vary thrust, effects of CAC and shroud dimensions on thrust and weight, some representative electrode configurations, and several alternative designs, including one in which the basic CAC configuration would be modified into something shaped like a conventional rocket engine with converging/diverging nozzle and an anode with gas feed in the space that, in a conventional rocket engine, would be the combustion chamber.

  9. Static, cylindrically symmetric strings in general relativity with cosmological constant

    SciTech Connect

    Linet, B.

    1986-07-01

    The static, cylindrically symmetric solutions to Einstein's equations with a cosmological term describing cosmic strings are determined. The discussion depends on the sign of the cosmological constant.

  10. Experimental and theoretical studies of cylindrical Hall thrusters

    SciTech Connect

    Smirnov, Artem; Raitses, Yegeny; Fisch, Nathaniel J.

    2007-05-15

    The Hall thruster is a mature electric propulsion device that holds considerable promise in terms of the propellant saving potential. The annular design of the conventional Hall thruster, however, does not naturally scale to low power. The efficiency tends to be lower and the lifetime issues are more aggravated. Cylindrical geometry Hall thrusters have lower surface-to-volume ratio than conventional thrusters and, thus, seem to be more promising for scaling down. The cylindrical Hall thruster (CHT) is fundamentally different from the conventional design in the way the electrons are confined and the ion space charge is neutralized. The performances of both the large (9-cm channel diameter, 600-1000 W) and miniaturized (2.6-cm channel diameter, 50-300 W) CHTs are comparable with those of the state-of-the-art conventional (annular) design Hall thrusters of similar sizes. A comprehensive experimental and theoretical study of the CHT physics has been conducted, addressing the questions of electron cross-field transport, propellant ionization, plasma-wall interaction, and formation of the electron distribution function. Probe measurements in the harsh plasma environment of the microthruster were performed. Several interesting effects, such as the unusually high ionization efficiency and enhanced electron transport, were observed. Kinetic simulations suggest the existence of the strong fluctuation-enhanced electron diffusion and predict the non-Maxwellian shape of the electron distribution function. Through the acquired understanding of the new physics, ways for further optimization of this means for low-power space propulsion are suggested. Substantial flexibility in the magnetic field configuration of the CHT is the key tool in achieving the high-efficiency operation.

  11. Electron Cross-field Transport in a Miniaturized Cylindrical Hall Thruster

    SciTech Connect

    Smirnov Artem, Raitses Yevgeny, Fisch Nathaniel J

    2005-10-14

    Conventional annular Hall thrusters become inefficient when scaled to low power. Cylindrical Hall thrusters, which have lower surface-to-volume ratio, are more promising for scaling down. They presently exhibit performance comparable with conventional annular Hall thrusters. The present paper gives a review of the experimental and numerical investigations of electron crossfield transport in the 2.6 cm miniaturized cylindrical Hall thruster (100 W power level). We show that, in order to explain the discharge current observed for the typical operating conditions, the electron anomalous collision frequency {nu}{sub b} has to be on the order of the Bohm value, {nu}{sub B} {approx} {omega}{sub c}/16. The contribution of electron-wall collisions to cross-field transport is found to be insignificant. The optimal regimes of thruster operation at low background pressure (below 10{sup -5} Torr) in the vacuum tank appear to be different from those at higher pressure ({approx} 10{sup -4} Torr).

  12. Electrochemical cell having cylindrical electrode elements

    DOEpatents

    Nelson, Paul A.; Shimotake, Hiroshi

    1982-01-01

    A secondary, high temperature electrochemical cell especially adapted for lithium alloy negative electrodes, transition metal chalcogenide positive electrodes and alkali metal halide or alkaline earth metal halide electrolyte is disclosed. The cell is held within an elongated cylindrical container in which one of the active materials is filled around the outside surfaces of a plurality of perforate tubular current collectors along the length of the container. Each of the current collector tubes contain a concentric tubular layer of electrically insulative ceramic as an interelectrode separator. The active material of opposite polarity in elongated pin shape is positioned longitudinally within the separator layer. A second electrically conductive tube with perforate walls can be swagged or otherwise bonded to the outer surface of the pin as a current collector and the electrically insulative ceramic layer can be coated or otherwise layered onto the outer surface of this second current collector. Alternatively, the central pin electrode can include an axial core as a current collector.

  13. Premixed flames in closed cylindrical tubes

    NASA Astrophysics Data System (ADS)

    Metzener, Philippe; Matalon, Moshe

    2001-09-01

    We consider the propagation of a premixed flame, as a two-dimensional sheet separating unburned gas from burned products, in a closed cylindrical tube. A nonlinear evolution equation, that describes the motion of the flame front as a function of its mean position, is derived. The equation contains a destabilizing term that results from the gas motion induced by thermal expansion and has a memory term associated with vorticity generation. Numerical solutions of this equation indicate that, when diffusion is stabilizing, the flame evolves into a non-planar form whose shape, and its associated symmetry properties, are determined by the Markstein parameter, and by the initial data. In particular, we observe the development of convex axisymmetric or non-axisymmetric flames, tulip flames and cellular flames.

  14. Naked singularity resolution in cylindrical collapse

    SciTech Connect

    Kurita, Yasunari; Nakao, Ken-ichi

    2006-03-15

    In this paper, we study the gravitational collapse of null dust in cylindrically symmetric spacetime. The naked singularity necessarily forms at the symmetry axis. We consider the situation in which null dust is emitted again from the naked singularity formed by the collapsed null dust and investigate the backreaction by this emission for the naked singularity. We show a very peculiar but physically important case in which the same amount of null dust as that of the collapsed one is emitted from the naked singularity as soon as the ingoing null dust hits the symmetry axis and forms the naked singularity. In this case, although this naked singularity satisfies the strong curvature condition by Krolak (limiting focusing condition), geodesics which hit the singularity can be extended uniquely across the singularity. Therefore, we may say that the collapsing null dust passes through the singularity formed by itself and then leaves for infinity. Finally, the singularity completely disappears and the flat spacetime remains.

  15. Cylindrical spreading due to downwind refraction.

    PubMed

    Makarewicz, Rufin

    2016-04-01

    Downwind propagation is analyzed for a low level jet (LLJ). The LLJ is characterized by a wind speed maximum (at least 10-20 m/s with peak speeds up to 30 m/s) a few hundred meters above the ground. Close to an elevated point source, such as a wind turbine or an aircraft, spherical spreading results in a 6 dB decrease in sound level per doubling of the distance. Wind turbine noise measurements show that at a transition distance, the downwind propagation changes the spherical spreading into a cylindrical spreading with a 3 dB decrease. It is shown how the transition distance and sound intensity depend on the LLJ parameters. The pivotal phenomenon is the non-coherent superposition of ground reflected rays in the turbulent atmosphere. PMID:27106309

  16. Dispersive cylindrical cloaks under nonmonochromatic illumination

    NASA Astrophysics Data System (ADS)

    Argyropoulos, Christos; Kallos, Efthymios; Hao, Yang

    2010-01-01

    Transformation-based cylindrical cloaks and concentrators are illuminated with nonmonochromatic waves and unusual effects are observed with interesting potential applications. The transient responses of the devices are studied numerically with the finite-difference time-domain method and the results are verified with analytical formulas. We compute the effective bandwidth of several cloaking schemes as well as the effect of losses on the performance of the structures. We also find that narrowband behavior, frequency shift effects, time delays, and spatial disturbances of the incoming waves are dominant due to the inherently dispersive nature of the devices. These effects are important and should be taken into account when designing metamaterial-based devices.

  17. Plasmonic oligomers in cylindrical vector light beams

    PubMed Central

    Hentschel, Mario; Dorfmüller, Jens; Jäger, Sebastian; Kern, Andreas M; Braun, Kai; Zhang, Dai; Meixner, Alfred J

    2013-01-01

    Summary We investigate the excitation as well as propagation of magnetic modes in plasmonic nanostructures. Such structures are particularly suited for excitation with cylindrical vector beams. We study magneto-inductive coupling between adjacent nanostructures. We utilize high-resolution lithographic techniques for the preparation of complex nanostructures consisting of gold as well as aluminium. These structures are subsequently characterized by linear optical spectroscopy. The well characterized and designed structures are afterwards studied in depth by exciting them with radial and azimuthally polarized light and simultaneously measuring their plasmonic near-field behavior. Additionally, we attempt to model and simulate our results, a project which has, to the best of our knowledge, not been attempted so far. PMID:23400561

  18. Method for making generally cylindrical underground openings

    DOEpatents

    Routh, J.W.

    1983-05-26

    A rapid, economical and safe method for making a generally cylindrical underground opening such as a shaft or a tunnel is described. A borehole is formed along the approximate center line of where it is desired to make the underground opening. The borehole is loaded with an explodable material and the explodable material is detonated. An enlarged cavity is formed by the explosive action of the detonated explodable material forcing outward and compacting the original walls of the borehole. The enlarged cavity may be increased in size by loading it with a second explodable material, and detonating the second explodable material. The process may be repeated as required until the desired underground opening is made. The explodable material used in the method may be free-flowing, and it may be contained in a pipe.

  19. Ion orbits in a cylindrical Langmuir probe

    SciTech Connect

    Taccogna, Francesco; Longo, Savino; Capitelli, Mario

    2006-04-15

    It has been suggested that in weakly collisional sheaths, potential wells and barriers could appear due to ion-neutral momentum and charge transfer collisions. These can cause the presence of repulsed and trapped ions in the region surrounding a negatively biased Langmuir probe, invalidating the commonly used orbital-motion-limited theory of ion current. This is still an open question concerning also the charging and shielding of dust grains, and at present, no fully self-consistent treatment exists. For this reason, a particle-in-cell/test-particle Monte Carlo simulation of the dynamics of an argon plasma in the region surrounding an attracting cylindrical probe at medium gas pressure has been developed. The results of the present simulation for different probe potentials and discharge pressures demonstrate the complex structure of electric potential around the probe and the failure of collisionless theories.

  20. Potential flow inside an evaporating cylindrical line.

    PubMed

    Petsi, A J; Burganos, V N

    2005-10-01

    An analytical solution to the problem of potential flow inside an evaporating line is obtained. The line is shaped as a half-cylinder lying on a substrate, and evaporates with either pinned or depinned contact lines. The solution is provided through the technique of separation of variables in the velocity potential and stream function formulations. Based on the flow field calculations, it is estimated that the coffee-stain phenomenon should be expected even for uniform evaporation flux throughout the cylindrical surface, provided that the contact lines remain anchored. A simple expression for the velocity potential is also suggested, which reproduces the local velocity vector with excellent accuracy. The vertically averaged velocity is calculated also for other contact line values, revealing for any value an outward liquid flow for pinned lines as opposed to inward flow for depinned lines. PMID:16383581

  1. SPSM and its application in cylindrical shells

    NASA Astrophysics Data System (ADS)

    Nie, Wu; Zhou, Su-Lian; Peng, Hui

    2008-03-01

    In naval architectures, the structure of prismatic shell is used widely. But there is no suitable method to analyze this kind of structure. Stiffened prismatic shell method (SPSM) presented in this paper, is one of the harmonic semi-analytic methods. Theoretically, strong stiffened structure can be analyzed economically and accurately. SPSM is based on the analytical solution of the governing differential equations for orthotropic cylindrical shells. In these differential equations, the torsional stiffness, bending stiffness and the exact position of each stiffener are taken into account with the Heaviside singular function. An algorithm is introduced, in which the actions of stiffeners on shells are replaced by external loads at each stiffener position. Stiffened shells can be computed as non-stiffened shells. Eventually, the displacement solution of the equations is acquired by the introduction of Green function. The stresses in a corrugated transverse bulkhead without pier base of an oil tanker are computed by using SPSM.

  2. Concentration profiles in drying cylindrical filaments

    NASA Astrophysics Data System (ADS)

    Czaputa, Klaus; Brenn, Günter; Meile, Walter

    2008-12-01

    We analyze theoretically the drying of cylindrical filaments. For modelling the mass transfer on the gas side of the liquid-gas interface of the shrinking circular cylindrical filament, we apply the model of Abramzon and Sirignano, which was originally developed for spherical geometry. As a consequence of mass transfer at constant Sherwood number, we obtain a d2-law for the shrinkage of the cylinder as in the case of the spherical geometry, which expresses that the cross-sectional area of the cylinder shrinks at a constant rate with time. For this situation, the diffusion equation for the liquid phase mixture components becomes separable upon transformation into similarity coordinates and is solved analytically to obtain the concentration profiles inside the filament as functions of time. The dependency of the profiles on the radial coordinate is determined by a series of Kummer’s functions. Applying this result, we study the evolution of the concentration profiles in the liquid phase with time as dependent on a parameter given as the ratio of rate of shrinkage of the cross-sectional area of the cylinder to liquid-phase diffusion coefficient, which was identified as relevant for the shape of the concentration profiles formed in the liquid during the drying process. As an example, we present computed results for the constant evaporation rate regime in the dry-spinning process of a polyvinyl-alcohol (PVA)-water system. Comparison of our analytical results with full numerical solutions of the diffusion equation from the literature, achieved with concentration-dependent diffusion coefficient, reveals very good agreement.

  3. Low-mass, high-rate cylindrical MWPC's for the MEGA experiment

    SciTech Connect

    Mischke, R.E.; Armijo, V.; Black, J.K.; Bolton, R.D.; Carius, S.; Cooper, M.D.; Espinoza, C.; Hart, G.W.; Hogan, G.E.; Piilonen, L.E.; Sandoval, J.; Schilling, S.; Sena, J.; Stanislaus, S.; Suazo, G.; Szymanski, J.J.; Whitehouse, D.A.; Wilkinson, C.A. ); Fisk, R.; Koetke, D.D.; Manweiler, R.W. ); Jui, C. )

    1990-01-01

    The construction of MWPCs for the MEGA experiment at LAMPF are described. The chambers are cylindrical, low mass (3 {times} 10{sup {minus}4} radiation lengths), and are designed to operate at high rates (3 {times} 10{sup 4} /mm{sup 2}/s). Several novel construction techniques have been developed and custom electronics have been designed to help achieve the required performance, which corresponds to that needed at high luminosity colliders. 4 refs., 3 figs.

  4. Process simulation of modified dry grind ethanol plant with recycle of pretreated and enzymatically hydrolyzed distillers' grains.

    PubMed

    Kim, Youngmi; Mosier, Nathan; Ladisch, Michael R

    2008-08-01

    Distillers' grains (DG), a co-product of a dry grind ethanol process, is an excellent source of supplemental proteins in livestock feed. Studies have shown that, due to its high polymeric sugar contents and ease of hydrolysis, the distillers' grains have potential as an additional source of fermentable sugars for ethanol fermentation. The benefit of processing the distillers' grains to extract fermentable sugars lies in an increased ethanol yield without significant modification in the current dry grind technology. Three different potential configurations of process alternatives in which pretreated and hydrolyzed distillers' grains are recycled for an enhanced overall ethanol yield are proposed and discussed in this paper based on the liquid hot water (LHW) pretreatment of distillers' grains. Possible limitations of each proposed process are also discussed. This paper presents a compositional analysis of distillers' grains, as well as a simulation of the modified dry grind processes with recycle of distillers' grains. Simulated material balances for the modified dry grind processes are established based on the base case assumptions. These balances are compared to the conventional dry grind process in terms of ethanol yield, compositions of its co-products, and accumulation of fermentation inhibitors. Results show that 14% higher ethanol yield is achievable by processing and hydrolyzing the distillers' grains for additional fermentable sugars, as compared to the conventional dry grind process. Accumulation of fermentation by-products and inhibitory components in the proposed process is predicted to be 2-5 times higher than in the conventional dry grind process. The impact of fermentation inhibitors is reviewed and discussed. The final eDDGS (enhanced dried distillers' grains) from the modified processes has 30-40% greater protein content per mass than DDGS, and its potential as a value-added process is also analyzed. While the case studies used to illustrate the

  5. The clenching-grinding spectrum and fear circuitry disorders: clinical insights from the neuroscience/paleoanthropology interface.

    PubMed

    Bracha, H Stefan; Ralston, Tyler C; Williams, Andrew E; Yamashita, Jennifer M; Bracha, Adam S

    2005-04-01

    This review discusses the clenching-grinding spectrum from the neuropsychiatric/neuroevolutionary perspective. In neuropsychiatry, signs of jaw clenching may be a useful objective marker for detecting or substantiating a self-report of current subjective emotional distress. Similarly, accelerated tooth wear may be an objective clinical sign for detecting, or substantiating, long-lasting anxiety. Clenching-grinding behaviors affect at least 8 percent of the population. We argue that during the early paleolithic environment of evolutionary adaptedness, jaw clenching was an adaptive trait because it rapidly strengthened the masseter and temporalis muscles, enabling a stronger, deeper and therefore more lethal bite in expectation of conflict (warfare) with conspecifics. Similarly, sharper incisors produced by teeth grinding may have served as weaponry during early human combat. We posit that alleles predisposing to fear-induced clenching-grinding were evolutionarily conserved in the human clade (lineage) since they remained adaptive for anatomically and mitochondrially modern humans (Homo sapiens) well into the mid-paleolithic. Clenching-grinding, sleep bruxism, myofacial pain, craniomaxillofacial musculoskeletal pain, temporomandibular disorders, oro-facial pain, and the fibromyalgia/chronic fatigue spectrum disorders are linked. A 2003 Cochrane meta-analysis concluded that dental procedures for the above spectrum disorders are not evidence based. There is a need for early detection of clenching-grinding in anxiety disorder clinics and for research into science-based interventions. Finally, research needs to examine the possible utility of incorporating physical signs into Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition posttraumatic stress disorder diagnostic criteria. One of the diagnostic criterion that may need to undergo a revision in Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition is Criterion D (persistent fear

  6. Development of the Cylindrical Wire Electrical Discharge Machining Process.

    SciTech Connect

    McSpadden, SB

    2002-01-22

    Results of applying the wire Electrical Discharge Machining (EDM) process to generate precise cylindrical forms on hard, difficult-to-machine materials are presented. A precise, flexible, and corrosion-resistant underwater rotary spindle was designed and added to a conventional two-axis wire EDM machine to enable the generation of free-form cylindrical geometries. A detailed spindle error analysis identifies the major source of error at different frequency. The mathematical model for the material removal of cylindrical wire EDM process is derived. Experiments were conducted to explore the maximum material removal rate for cylindrical and 2D wire EDM of carbide and brass work-materials. Compared to the 2D wire EDM, higher maximum material removal rates may be achieved in the cylindrical wire EDM. This study also investigates the surface integrity and roundness of parts created by the cylindrical wire EDM process. For carbide parts, an arithmetic average surface roughness and roundness as low as 0.68 and 1.7 {micro}m, respectively, can be achieved. Surfaces of the cylindrical EDM parts were examined using Scanning Electron Microscopy (SEM) to identify the craters, sub-surface recast layers and heat-affected zones under various process parameters. This study has demonstrated that the cylindrical wire EDM process parameters can be adjusted to achieve either high material removal rate or good surface integrity.

  7. A compact cylindrical-shape microstrip structure with cloaking properties for mutual coupling reduction in array antennas

    NASA Astrophysics Data System (ADS)

    Naqvi, Syed Aftab

    A cylindrical-shaped microstrip structure with cloaking properties is presented as a shielding device to reduce the mutual coupling between two patch antennas. The surface comprises of a number of 2-port microstrip (2-PM) elements printed on individual substrates and, to enclose a particular region, several 2-PM elements are interconnected into a cylindrical shape. Each 2-PM element has the capability of coupling an incident EM field on the surface to the adjacent interconnected elements. Then, because the 2-PM elements are connected into a cylindrical shape, the incident EM field is re-radiated from the other interconnected 2-PM elements in a direction away from the transmitter; achieving a behavior similar to a cloak. The prototypes in this dissertation illustrates that this surface has the additional benefit of overcoming many of the manufacturing difficulties of traditional cloaks because microstrip structures are used. To demonstrate this concept, a cylindrical surface operating at 3.89 GHz and a frequency reconfigurable surface (consisting of 2-port frequency reconfigurable microstrip elements (2-PFRM)) operating at 3.68 GHz and 3.89 GHz is simulated in HFSS, manufactured and measured in a full anechoic chamber. Moreover, as an application, the cylindrical surface operating at 3.89 GHz is used to reduce the mutual coupling between two patch antennas operating simultaneously at 3.89 GHz. The radiation pattern and the gain of a 2-element array is measured to demonstrate the negligible effects of a cylindrical surface on the far field antenna array parameters. Simulation and measurement results are in good agreement and validate the proposed EM cloak-based surface for applications such as antenna array shielding, radar cross section and communications in complex EM environments.

  8. Effect of grinding and heat treatment on the mechanical behavior of zirconia ceramic.

    PubMed

    Ramos, Gabriela Freitas; Pereira, Gabriel Kalil Rocha; Amaral, Marina; Valandro, Luiz Felipe; Bottino, Marco Antonio

    2016-01-01

    The present study investigated the effect of grinding on roughness, flexural strength, and reliability of a zirconia ceramic before and after heat treatment. Seven groups were tested (n = 15): a control group (labeled CG, untreated), and six groups of samples ground with diamond discs, simulating diamond burs, with grits of 200 µm (G80); 160 µm (G120), and 25 µm (G600), either untreated or heat-treated at 1200°C for 2 h (labeled A). Yttria tetragonal zirconia polycrystal discs were manufactured, ground, and submitted to roughness and crystalline phase analyses before the biaxial flexural strength test. There was no correlation between roughness (Ra and Rz) and flexural strength. The reliability of the materials was not affected by grinding or heat treatment, but the characteristic strength was higher after abrasion with diamond discs, irrespective of grit size. The X-ray diffraction data showed that grinding leads to a higher monoclinic (m) phase content, whereas heat treatment produces reverse transformation, leading to a fraction of m-phase in ground samples similar to that observed in the control group. However, after heat treatment, only the G80A samples presented strength similar to that of the control group, while the other groups showed higher strength values. When zirconia pieces must be adjusted for clinical use, a smoother surface can be obtained by employing finer-grit diamond burs. Moreover, when the amount of monoclinic phase is related to the degradation of zirconia, the laboratory heat treatment of ground pieces is indicated for the reverse transformation of zirconia crystals. PMID:26676188

  9. Rheology of coal-water slurries prepared by the HP roll mill grinding of coal

    SciTech Connect

    Fuerstenau, D.W.

    1992-12-01

    The objective of the research is the development of improved technology for the preparation of coal-water slurries, which have potential for replacing fuel oil in direct combustion. The fine grinding of coal is a crucial step in the manufacture of coal-water slurries. In this context, currently available grinding mills exhibit poor energy efficiency for size reduction and non-optimum packing characteristics of the ground coal. The first increases the cost of manufacture of coal-water slurries and the second adversely affects their rheological properties. The newly invented choke-fed, high-pressure roll mill is up to 50% more energy efficient and, moreover, there are reasons to believe that it produces a size distribution of ground particles which is closer to the dense packing composition. The high-pressure roll mill (which is perhaps the only really significant innovation in industrial comminution in this century) has lower capital cost, occupies less floor space, shows negligible wear rate, accepts feed with a wide range of moisture contents and, of particular importance, it can be scaled up to grind hundreds of tons of solids per hour. The high-pressure roll mill provides a unique opportunity to develop an improved technology for preparing coal-water slurries. Our research group in the University of California at Berkeley not only has a fully instrumented, laboratory-scale, choke-fed. high-pressure roll mill (the only one of its kind in the United States) but also fully instrumented laboratory ball mills for comparative fine coal preparation purposes. In this research program, our plans are to systematically investigate comminution energy consumption, deagglomeration procedures, and the stability and rheology of coal-water slurry fuel prepared with high-pressure roll mill, and to compare the results with slurry prepared with ball-milled coal.

  10. The effect of local exhaust ventilation controls on dust exposures during concrete cutting and grinding activities.

    PubMed

    Croteau, Gerry A; Guffey, Steven E; Flanagan, Mary Ellen; Seixas, Noah S

    2002-01-01

    This study assessed the effectiveness of commercially available local exhaust ventilation (LEV) systems for controlling respirable dust and crystalline silica exposures during concrete cutting and grinding activities. Work activities were performed by union-sponsored apprentices and included tuck-point grinding, surface grinding, paver block and brick cutting (masonry saw), and concrete block cutting (hand-held saw). In a randomized block design, implemented under controlled field conditions, three ventilation rates (0, 30, and 75 cfm) were tested for each tool. Each ventilation treatment was replicated three times in random order for a total of nine 15-min work sessions per study subject. With the exception of the hand-held saw, the use of LEV resulted in a significant (p < 0.05) reduction in respirable dust exposure. Mean exposure levels for the 75 cfm treatments were less than that of the 30 cfm treatments; however, differences between these two treatments were only significant for paver block cutting (p < 0.01). Although exposure reduction was significant (70-90% at the low ventilation rate and 80-95% reduction at the high ventilation rate), personal respirable dust [corrected] exposures remained very high: 1.4-2.8 x PEL (permissible exposure limit) at the low ventilation rate and 0.9-1.7 x PEL at the high ventilation rate. Exposure levels found under actual field conditions would likely be lower due to the intermittent nature of most job tasks. Despite incomplete control LEV has merit, as it would reduce the risk of workers developing disease, allow workers to use a lower level of respiratory protection, protect workers during short duration work episodes reduce exposure to nearby workers, and reduce clean-up associated dust exposures. PMID:12486779

  11. Development and mechanical characterization of a polypropylene (pp) composite with grinding sludge as fiber

    NASA Astrophysics Data System (ADS)

    Rodrigues, D. A.; Oliveira, A. S. M.; Specht, R. F.; Santana, R. M. C.

    2014-05-01

    The search for alternative materials that provide reduced costs in manufacturing processes, and the need of to recycle materials normally disposable, it has aroused great interest and much research, with regard to reduction of material consumption due to its high cost and scarcity. Within this focus, this work aims to characterize a thermoplastic composite, whose polymer matrix is polypropylene (PP), and as disperse phase "grinding sludge, GS" from the various machining processes for grinding. After drying and sieving the GS and its subsequent mixing with the thermoplastic resin to prepare the PP/GS composites formulated were 80/20, 70/30, 60/40 w/w. The composite was injected into an injection mold in the form specimen test. The specimens followed the ASTM D638 and ASTM D256 for tensile and impact respectively. Three processing parameters were varied: the content of GS, temperature and injection rate. Each of these variables has three levels: L (low), M (medium) and H (high), making all possible combinations, totaling 27 processing conditions. The experimental conditions followed a statistical design obtained with the software Statgraphics Centurion, where the effects of variables are studied according to their statistical significance. An analysis of MEV and EDS was performed to obtain the characteristics of the "grinding sludge" (geometry and composition). Despite having been sifted, the geometry of the GS was still very rough, with varied shapes and sizes, and even made up a small percentage of abrasive grains. The variable that most influenced the mechanical properties was the content of particulate GS. The values obtained for the maximum tensile strength not behaved in descending order as expected, this may be the effect of small amount of samples tested. The results of the mechanical properties showed that for the elasticity modulus increased with increasing of GS; the values of elongation and impact strength decreased with increasing of GS.

  12. Development and Experimental Study of Surface-Electrical Discharge Diamond Grinding of Al-10 wt%SiC Composite

    NASA Astrophysics Data System (ADS)

    Agrawal, Shyam Sunder; Yadava, Vinod

    2016-01-01

    As silicon carbide possesses small fracture toughness, it is difficult to grind because it leads to cracking. Metal matrix composites can be machined using electrical discharge machining (EDM) but the process is slow. Electrical discharge diamond grinding (EDDG), which consists of diamond grinding and EDM with a rotating disk which enhanced material removal rate (MRR) and produce better surface finish. This paper describes the machining characteristic of Al-SiC composite using EDDG in surface grinding configuration which is called as surface-electrical discharge diamond grinding (S-EDDG). A chain of experiments were performed on S-EDDG set up by mounting newly self designed and fabricated set up on conventional die sinking EDM machine using the approach of one parameter-at-a-time concept. Surface roughness (Ra) and MRR are taken as output parameters as both are important outcome in the manufacturing process and they materialize a major division in the manufacturing system. The effects of current, wheel speed and depth of cut is analyzed on MRR and Ra. Finally, optimization have been done through weighted principal component analysis.

  13. Cylindrical Implosion Experiments using Laser Direct Drive

    NASA Astrophysics Data System (ADS)

    Tubbs, David

    1998-11-01

    Development of high-gain targets for the National Ignition Facility relies considerably on computational modeling, and it is important that our codes are validated against relevant experimental data in convergent geometry.(W. J. Krauser et al., Phys. Plasmas 3, 2084 (1996); D. C. Wilson et al., Phys. Plasmas 5, 1953 (1998)) In collaboration with the University of Rochester, we have begun a campaign of hydrodynamic instability experiments in cylindrical geometry using direct drive,(D. L. Tubbs et al., submitted to Laser and Particle Beams (1998); C. W. Barnes et al., submitted to Rev. Sci. Instrm. (1998)) building on our success in indirect drive.( W. W. Hsing et al., Phys. Plasmas 5, 1832 (1997); W. W. Hsing and N. M. Hoffman, Phys. Rev. Lett., 3876 (1997)) Cylindrical targets facilitate direct diagnostic access to the convergent, hydrodynamic flow. The energy advantage of direct drive and its excellent target-illumination symmetry (achieved at OMEGA through use of Distributed Phase Plates and SSD) permit more energetic implosions, larger target scale (hence greater diagnostic resolution), longer acceleration timescales, and higher convergence than were possible using indirect drive. We estimate that specific laser energy delivered to the target for direct drive at OMEGA is roughly 4 times that achieved for indirect drive at Nova. Our first experiments (January 1998) yield excellent data for the first highly symmetrical direct-drive implosions, with which we benchmark zeroth-order hydrodynamic simulations. Two-dimensional (2-D) LASNEX calculations, using as-shot laser power histories and no further physics adjustments, match measured target-implosion data within theoretical and experimental errors. In addition, 2-D LASNEX simulations of single-mode (m=28, azimuthally symmetric) perturbation growth agree well with data obtained during our first week of experiments. For 1.5-micron initial perturbation amplitude, we observe Rayleigh-Taylor growth factors of order 10

  14. Converging cylindrical shocks in ideal magnetohydrodynamics

    SciTech Connect

    Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.

    2014-09-15

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=√(μ{sub 0}/p{sub 0}) I/(2 π) where I is the current, μ{sub 0} is the permeability, and p{sub 0} is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The

  15. Converging cylindrical shocks in ideal magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.

    2014-09-01

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=sqrt{μ _0/p_0} I/(2 π ) where I is the current, μ0 is the permeability, and p0 is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field

  16. Ammonia formation caused by the presence of water in the wet grinding of silicon nitride powder

    NASA Technical Reports Server (NTRS)

    Kanno, Y.; Suzuki, K.; Kuwahara, Y.

    1984-01-01

    Si3 N4 powder (amorphous, alpha-, and beta-Si3 N4) was mixed with MeOH containing 8.87 mol. % H2O and ground. The NH3 generation rapidly increased after a grinding time of 100 hours. Silicon nitride sintered material was chosen as one of the high temperature, high strength structural materials and studies of the control of the raw material powder, preparation of the sintered body (finding the right assistant, hot press, high pressure sintering, fracture toughness and oxidation at high temperature were performed.

  17. Real-time pressure monitoring for dynamic control during paper mill operation using fiber optic pressure sensors

    NASA Astrophysics Data System (ADS)

    Fielder, Robert S.; Boyd, Clark; Palmer, Matthew; Eriksen, Oddbjørn

    2006-03-01

    Fiber optic pressure sensors were integrated into the grinding plates of an operational paper pulp mill for real-time monitoring of the pulp grinding process. On-line system monitoring will allow smart, active control of the grinding plates thereby improving the quality and consistency of the pulp produced. Sensors were constructed and calibrated for use in the harsh environment of an operating paper pulp grinder. The sensors were 1.65mm in diameter including titanium housing, and were installed directly into the grooves of the grinding plates. The sensing elements were flush-mounted with the wall and exposed to the wood pulp slurry. Nine sensors were calibrated up to 1000psi. During operation, pressure was sampled at 1.0MHz, and pressure spikes up to 175psi were observed. Pressure pulses measured are due to the relative motion between the grooves and channels on two pulp grinding plates. The consistency, size distribution, and quality of paper pulp exiting from the grinder are directly related to the distance between the channels on the two rotating elements. The pressure pulses produced are also proportional to the distance between channels. Therefore, by monitoring pressure fluctuations, grinding elements can be dynamically controlled thereby producing a "smart mill."

  18. Grinding 'Grindstone'

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image taken by the Mars Exploration Rover Opportunity shows a target dubbed 'Grindstone' on a rock called 'Manitoba' in 'Endurance Crater.' Opportunity dug a hole into the target with its rock abrasion tool, then captured this picture with its microscopic imager on sol 152 (June 28, 2004). The image mosaic is about 6 centimeters (2.4 inches) across.

  19. Rotating cylindrical wormholes and energy conditions

    NASA Astrophysics Data System (ADS)

    Bronnikov, K. A.; Krechet, V. G.

    2016-01-01

    We seek wormholes among rotating cylindrically symmetric configurations in general relativity. Exact wormhole solutions are presented with such sources of gravity as a massless scalar field, a cosmological constant, and a scalar field with an exponential potential. However, none of these solutions are asymptotically flat, which excludes the existence of wormhole entrances as local objects in our Universe. To overcome this difficulty, we try to build configurations with flat asymptotic regions using the cut-and-paste procedure: on both sides of the throat, a wormhole solution is matched to a properly chosen region of flat space-time at some surfaces Σ- and Σ+. It is shown, however, that if the source of gravity in the throat region is a scalar field with an arbitrary potential, then one or both thin shells appearing on Σ- and Σ+ inevitably violate the null energy condition. Thus, although rotating wormhole solutions are easily found without exotic matter, such matter is still necessary for obtaining asymptotic flatness.

  20. Capillary effects on floating cylindrical particles

    NASA Astrophysics Data System (ADS)

    Dixit, Harish N.; Homsy, G. M.

    2012-12-01

    In this study, we develop a systematic perturbation procedure in the small parameter, B1/2, where B is the Bond number, to study capillary effects on small cylindrical particles at interfaces. Such a framework allows us to address many problems involving particles on flat and curved interfaces. In particular, we address four specific problems: (i) capillary attraction between cylinders on flat interface, in which we recover the classical approximate result of Nicolson ["The interaction between floating particles," Proc. Cambridge Philos. Soc. 45, 288-295 (1949), 10.1017/S0305004100024841], thus putting it on a rational basis; (ii) capillary attraction and aggregation for an infinite array of cylinders arranged on a periodic lattice, where we show that the resulting Gibbs elasticity obtained for an array can be significantly larger than the two cylinder case; (iii) capillary force on a cylinder floating on an arbitrary curved interface, where we show that in the absence of gravity, the cylinder experiences a lateral force which is proportional to the gradient of curvature; and (iv) capillary attraction between two cylinders floating on an arbitrary curved interface. The present perturbation procedure does not require any restrictions on the nature of curvature of the background interface and can be extended to other geometries.

  1. Buckling analysis of cylindrical shells with cracks

    SciTech Connect

    Limam, A.; Jullien, J.F.; Ouayou, B.S.

    1995-12-31

    In many areas of aeronautical nuclear and civil engineering practice, large thin-walled structural panels are increasingly becoming characteristic architectural features. Indeed, nuclear reactor vessels and cryogenic tanks of a launcher, for instance, are made up of several thin-walled panels welded together. Instability and buckling phenomenon present over-riding constraints on the design process. In addition, the presence of joints which are very often the origin of surface fissures poses increasing dangers on the overall stability of these structures. This research deals with the analysis of the effects of cracks on the behavior of cylindrical shells subject to external pressure. The study was divided into two major parts. In the first part, experiments were carried out with shells without cracks, in order to obtain reference data. A numerical study of various models explains the experimental results and shows the combined effect of the geometric imperfections and boundary conditions on the critical load. The second part focused on several experimental tests and numerical simulations on shells with in- depth fissures as a function of their population, orientation, length and position with respect to the welds or joints. The agreement between numerical and experimental results confirms the new possibility to design with the aid of the finite element program under the condition that the calculations are carried out by means of an appropriate numerical method.

  2. Technology Selections for Cylindrical Compact Fabrication

    SciTech Connect

    Jeffrey A. Phillips

    2010-10-01

    A variety of process approaches are available and have been used historically for manufacture of cylindrical fuel compacts. The jet milling, fluid bed overcoating, and hot press compacting approach being adopted in the U.S. AGR Fuel Development Program for scale-up of the compacting process involves significant paradigm shifts from historical approaches. New methods are being pursued because of distinct advantages in simplicity, yield, and elimination of process mixed waste. Recent advances in jet milling technology allow simplified dry matrix powder preparation. The matrix preparation method is well matched with patented fluid bed powder overcoating technology recently developed for the pharmaceutical industry and directly usable for high density fuel particle matrix overcoating. High density overcoating places fuel particles as close as possible to their final position in the compact and is matched with hot press compacting which fully fluidizes matrix resin to achieve die fill at low compacting pressures and without matrix end caps. Overall the revised methodology provides a simpler process that should provide very high yields, improve homogeneity, further reduce defect fractions, eliminate intermediate grading and QC steps, and allow further increases in fuel packing fractions.

  3. Force balances in systems of cylindrical polyelectrolytes.

    PubMed

    Brenner, S L; McQuarrie, D A

    1973-04-01

    A detailed analysis is made of the model system of two parallel cylindrical polyelectrolytes which contain ionizable groups on their surfaces and are immersed in an ionic bathing medium. The interaction between the cylinders is examined by considering the interplay between repulsive electrostatic forces and attractive forces of electrodynamic origin. The repulsive force arises from the screened coulomb interaction between the surface charge distributions on the cylinders and has been treated by developing a solution to the linearized Poisson-Boltzmann equation. The boundary condition at the cylinder surfaces is determined as a self-consistent functional of the potential, with the input consisting of the density of ionizable groups and their dissociation constants. It is suggested that a reasonably accurate representation for the form of the attractive force can be obtained by performing a pairwise summation of the individual interatomic forces. A quantitative estimate is obtained using a Hamaker constant chosen on the basis of rigorous calculations on simpler systems. It is found that a balance exists between these repulsive and attractive forces at separations in good agreement with those observed in arrays of tobacco mosaic virus and in the A band myosin lattice in striated muscle. The behavior of the balance point as a function of the pH and ionic strength of the bathing medium closely parallels that seen experimentally. PMID:4696760

  4. Cylindrical converging shock initiation of reactive materials

    NASA Astrophysics Data System (ADS)

    Jenkins, Charles M.; Horie, Yasuyuki; Lindsay, Christopher Michael; Butler, George C.; Lambert, David; Welle, Eric

    2012-03-01

    Recent research has been conducted that builds on the Forbes et al. (1997) study of inducing a rapid solid state reaction in a highly porous core using a converging cylindrical shock driven by a high explosive. The high explosive annular charge used in this research to compress the center reactive core was comparable to PBXN-110. Some modifications were made on the physical configuration of the test item for scale-up and ease of production. The reactive materials (I2O5/Al and I2O5/Al/Teflon) were hand mixed and packed to a tap density of about 32 percent. Data provided by a Cordon 114 high speed framing camera and a Photon Doppler Velocimetry instrument provided exit gas expansion, core particle and cylinder wall velocities. Analysis indicates that the case expansion velocity differs according to the core formulation and behaved similar to the baseline high explosive core with the exit gas of the reactive materials producing comparable velocities. Results from CTH hydrocode used to model the test item compares favorably to the experimental results.

  5. Leaf wetness duration measurement: comparison of cylindrical and flat plate sensors under different field conditons

    NASA Astrophysics Data System (ADS)

    Sentelhas, Paulo C.; Gillespie, Terry J.; Santos, Eduardo A.

    2007-03-01

    In general, leaf wetness duration (LWD) is a key parameter influencing plant disease epidemiology, since it provides the free water required by pathogens to infect foliar tissue. LWD is used as an input in many disease warning systems, which help growers to decide the best time to spray their crops against diseases. Since there is no observation standard either for sensor or exposure, LWD measurement is often problematic. To assess the performance of electronic sensors, LWD measurements obtained with painted cylindrical and flat plate sensors were compared under different field conditions in Elora, Ontario, Canada, and in Piracicaba, São Paulo, Brazil. The sensors were tested in four different crop environments—mowed turfgrass, maize, soybean, and tomatoes—during the summer of 2003 and 2004 in Elora and during the winter of 2005 in Piracicaba. Flat plate sensors were deployed facing north and at 45° to horizontal, and cylindrical sensors were deployed horizontally. At the turfgrass site, both sensors were installed 30 cm above the ground, while at the crop fields, the sensors were installed at the top and inside the canopy (except for maize, with a sensor only at the top). Considering the flat plate sensor as a reference (Sentelhas et al. Operational exposure of leaf wetness sensors. Agric For Meteorol 126:59-72, 2004a), the results in the more humid climate at Elora showed that the cylindrical sensor overestimated LWD by 1.1-4.2 h, depending on the crop and canopy position. The main cause of the overestimation was the accumulation of big water drops along the bottom of the cylindrical sensors, which required much more energy and, consequently, time to evaporate. The overall difference between sensors when evaporating wetness formed during the night was around 1.6 h. Cylindrical sensors also detected wetness earlier than did flat plates—around 0.6 h. Agreement between plate and cylinder sensors was much better in the drier climate at Piracicaba. These

  6. Influence of cubic boron nitride grinding on the fatigue strengths of carbon steels and a nickel-base superalloy

    SciTech Connect

    Kawagoishi, N.; Chen, Q.; Kondo, E.; Goto, M.; Nisitani, H.

    1999-04-01

    The influence of cubic boron nitride (CBN) grinding on fatigue strength was investigated on an annealed carbon steel, a quenched and tempered carbon steel at room temperature, and a nickel-base superalloy, Inconel 718, at room temperature and 500 C. The results were discussed from several viewpoints, including surface roughness, residual stress, and work hardening or softening due to CBN grinding. The fatigue strength increased upon CBN grinding at room temperature, primarily because of the generation of compressive residual stress in the surface region. However, in the case of Inconel 718, this marked increase in the fatigue strength tended to disappear at the elevated temperature due to the release of compressive residual stress and the decrease of crack growth resistance at an elevated temperature.

  7. The effect of grinding at various vacuum levels on the color, phenolics, and antioxidant properties of apple.

    PubMed

    Kim, Ah-Na; Kim, Hyun-Jin; Kerr, William L; Choi, Sung-Gil

    2017-02-01

    The purpose of this study was to evaluate the effect of grinding at different vacuum levels (2.67, 6.67, 13.33, 19.99, and 101.33kPa) on key quality factors of apple. In the control apple, ground at atmospheric pressure of 101.33kPa, the antioxidant activities rapidly decreased within the first 30min, then plateaued thereafter, while enzymatic browning increased. When apples were ground and held under vacuum, changes in color and antioxidant activity were much less, and the least change was measured in samples prepared at the lowest pressure. Model fitting of the data showed that antioxidant activity decreased as a function of the logarithm of the absolute pressure. The results from analysis for key phenolic compounds including chlorogenic acid, procyanidin B2, and epicatechin indicated that these compounds were least changed at vacuum grinding at 2.67kPa, compared to atmospheric grinding. PMID:27596414

  8. Modeling and research of temperature distribution in surface layer of titanium alloy workpiece during AEDG and conventional grinding

    NASA Astrophysics Data System (ADS)

    Gołąbczak, M.; Gołąbczak, A.; Konstantynowicz, A.; Święcik, R.

    2016-06-01

    Titanium and its alloys are widely recognized as the hardly machinable materials, especially due to their relatively high hardness, low thermal conductivity and possible subcritical superplasticity. Then, a thorough control of the machining process parameters shall be maintained. In this paper, we have concentrated on the grinding of the Ti6Al4V titanium alloy using cBN (boron nitride) grinding wheel combined with the AEDG (abrasive electrodischarge grinding) process. The mathematical model we have dealt with has been based mainly on Jaeger model of the heat taking over between sliding bodies with substantial upgrades related to: estimation of the frictional heat generating based on friction forces distribution,

  9. Reproducible preparation of nanospray tips for capillary electrophoresis coupled to mass spectrometry using 3D printed grinding device.

    PubMed

    Tycova, Anna; Prikryl, Jan; Foret, Frantisek

    2016-04-01

    The use of high quality fused silica capillary nanospray tips is critical for obtaining reliable and reproducible electrospray/MS data; however, reproducible laboratory preparation of such tips is a challenging task. In this work, we report on the design and construction of low-cost grinding device assembled from 3D printed and commercially easily available components. Detailed description and characterization of the grinding device is complemented by freely accessible files in stl and skp format allowing easy laboratory replication of the device. The process of sharpening is aimed at achieving maximal symmetricity, surface smoothness and repeatability of the conus shape. Moreover, the presented grinding device brings possibility to fabricate the nanospray tips of desired dimensions regardless of the commercial availability. On several samples of biological nature (reserpine, rabbit plasma, and the mixture of three aminoacids), performance of fabricated tips is shown on CE coupled to MS analysis. The special interest is paid to the effect of tip sharpness. PMID:26626777

  10. Study of the vibration of bulkhead-stiffened cylindrical shells by laser-based methods

    NASA Astrophysics Data System (ADS)

    Zhu, Ninghui

    studied. The relationship between natural frequency loci veering, mode shape localization of steady state vibration and pass- stop-band behavior of wave propagation are established in stiffened cylindrical shell structures. It is hoped that this finding can be used to emphasis the importance of mode localization when the numerical models are applied to the study of dynamic behavior of real engineering structures. Finally, a novel laser-based vibration measurement system is developed. Rather than using a photographic camera as in conventional speckle photography, this system utilizes a CCD camera and an interfaced computer to perform the digital speckle image processing. Several algorithms are developed or found to extract the mode shapes related to the vibration of objects from captured digital speckle images. The algorithms can be generally categorized into the following aspects as spatial domain filtering (e.g., image edge detection operation), spectrum domain filtering (e.g., Fourier transform operation), spatial domain correlation and image blurring model. The computer generated or processed images can provide a Chladni-like pattern showing the mode shapes of vibrating objects. This new laser-based vibration measurement technique not only inherits the common merits shared by conventional optical schemes such as whole-field, non-contact and non-destruction, but also possesses its unique features of noise-resistance, simplicity, flexibility and, most of all, practicability. The feasibility of this new technique had been proven by successful field tests at the shipyard of General Dynamic Electric Boat Division.

  11. Experimental Simulation of Boiling Phenomena with a Cylindrical Annulus Moderator Cell

    SciTech Connect

    Lee, C.H.; Lee, D.J.; Chan, Y.K.; Chang, C.J.

    2002-07-01

    The improvement and utilization promotion project of the Taiwan Research Reactor (TRR-II) has been carried out at the Institute of Nuclear Energy Research (INER). The Cold Neutron Source (CNS) with a two-phase thermosyphon will be installed in the heavy water reactor. The hydrogen cold loop consists of a cylindrical moderator cell, a single transfer tube, and a condenser. A cylindrical annulus moderator cell consists of the outer shell and the inner shell of which bottom part is open. A series of mockup tests were performed by using the full-scale mock-up test facility and Freon-11 as a working fluid. The test results show that the inner shell contains only vapor and the outer shell contains boiling liquid for simulating the TRR-II CNS in the full power operations. The liquid level in the outer shell is stable without producing a sudden bubbling against the increase of 30% power. (authors)

  12. Effect of the annular region on the performance of a cylindrical Hall plasma thruster

    SciTech Connect

    Seo, Mihui; Lee, Jongsub; Choe, Wonho; Seon, Jongho; June Lee, Hae

    2013-02-15

    Performance characteristics of a cylindrical Hall thruster depending on the depth of the annular region (L{sub a}) in front of the anode were investigated. The effect of the annular region was examined by operating thrusters corresponding to four different values of L{sub a} (0, 4, 6, and 10 mm) and a fixed length of the cylindrical region (25 mm). Various measurements such as electron and ion currents, thrust, anode efficiency, current and propellant utilizations, and ion energy distribution functions were performed. Such measurements lead to an interpretation that (1) a considerable potential difference may exist between the anode and the ionization region, which is presumably located near the end of the annular region where magnetic field lines converge; (2) this potential difference increases with respect to increasing L{sub a}; and (3) the presence of the annular region near the anode reduces the specific impulse and anode efficiency for the examined thrusters.

  13. Numerical study of cathode emission constraints on cylindrical self-field MPD thruster performance

    NASA Technical Reports Server (NTRS)

    Lapointe, Michael R.

    1993-01-01

    A stability equation relating thruster discharge current, argon propellant mass flow rate, and electrode geometry has been solved for a variety of cylindrical self-field MPD thruster configurations and discharge currents. Realistic values for cathode emission current densities were used to provide additional constraints on the thruster geometries. A two-dimensional MPD code was employed to provide better estimates of the maximum achievable specific impulse, thrust, and flow efficiency for cases of interest. The model results indicate that long life, cylindrical self-field MPD thrusters operated with argon propellant may not be able to provide specific impulse values in excess of 2100s. Alternate electrode geometries, applied magnetic fields, and/or low molecular weight propellants may be necessary to achieve higher values of specific impulse.

  14. Limit of concentration for cylindrical concentrators under extended light sources.

    PubMed

    Miñano, J C; Luque, A

    1983-08-15

    Cylindrical concentrators illuminated by an extended source with an arbitrary distribution of radiance are analyzed taking into account basic properties derived from the Fermat principle and not from the specific concentrator shape. The upper limit of concentration achievable with this type of concentrator is obtained and it is found to be lower than that of general (3-D) concentrators. Cylindrical compound parabolic concentrators are analyzed in the light of this theory, and it is shown that they achieve the highest optical concentration possible for a cylindrical concentrator. PMID:18196152

  15. Mechano-chemical radical formation and polymerization initiation during wet grinding of alumina.

    PubMed

    Damm, C; Peukert, W

    2011-11-01

    The formation of free radicals during wet grinding of alumina in a stirred media mill was studied by using the test radical 2,2-diphenyl-1-picrylhydracyl (DPPH). The kinetics of mechano-chemical radical formation follows a zeroth-order rate law. Particle breakage as well as mechanical activation of the surface of the alumina particles contributes to the radical formation. The rate constants of the radical formation due to mechanical activation of the particle surface k(A) and due to particle breakage k(B) depend on the milling process parameters. The radical formation during wet grinding of alumina was exploited to initiate mechano-chemical polymerization reactions of acrylic acid and acryl amide, respectively. In this way nanoparticles functionalized with polyacrylic acid and polyacryl amide, respectively, are obtained. The influence of the milling process parameters on the kinetics of mechano-chemical radical formation and on the grafted amount of polymer is discussed on the basis of stress energy and number of stress events in the mill. A correlation between the grafted amount of polyacryl amide on the alumina particles and the total radical formation rate was found showing that the concentration of mechano-chemically formed free radicals governs the efficacy of a chemical reaction at activated particle surfaces. PMID:21820123

  16. Measuring grinding surface roughness based on the sharpness evaluation of colour images

    NASA Astrophysics Data System (ADS)

    Huaian, Y. I.; Jian, L. I. U.; Enhui, L. U.; Peng, A. O.

    2016-02-01

    Current machine vision-based detection methods for metal surface roughness mainly use the grey values of images for statistical analysis but do not make full use of the colour information and ignore the subjective judgment of the human vision system. To address these problems, this paper proposes a method to measure surface roughness through the sharpness evaluation of colour images. Based on the difference in sharpness of virtual images of colour blocks that are formed on grinding surfaces with different roughness, an algorithm for evaluating the sharpness of colour images that is based on the difference of the RGB colour space was used to develop a correlation model between the sharpness and the surface roughness. The correlation model was analysed under two conditions: constant illumination and varying illumination. The effect of the surface textures of the grinding samples on the image sharpness was also considered, demonstrating the feasibility of the detection method. The results show that the sharpness is strongly correlated with the surface roughness; when the illumination and the surface texture have the same orientation, the sharpness clearly decreases with increasing surface roughness. Under varying illumination, this correlation between the sharpness and surface roughness was highly robust, and the sharpness of each virtual image increased linearly with the illumination. Relative to the detection method for surface roughness using gray level co-occurrence matrix or artificial neural network, the proposed method is convenient, highly accurate and has a wide measurement range.

  17. Influence of environment and grinding on the crystallisation mechanism of ZrO2 gel

    NASA Astrophysics Data System (ADS)

    Criado, J. M.; González, M.; Diánez, M. J.; Pérez-Maqueda, L. A.; Málek, Jiri

    2007-05-01

    The influence of grinding and surrounding atmosphere on the thermal transformations of zirconia gel has been studied. The XRD analysis of the products obtained by thermal decomposition of zirconia gel has shown that pure tetragonal phase is obtained if the gel decomposition is carried out under high vacuum or dry inert atmosphere, while monoclinic zirconia results from the decomposition of the zirconia gel under air or inert gas saturated with water vapour. A mechanism for the thermal crystallisation of zirconia gel has been proposed from the study of the variation of the crystal size of the monoclinic and tetragonal zirconia phases formed as a function of the temperature and the surrounding atmosphere. The thermal decomposition of ground zirconia leads to the formation of ZrO2 with a percentage of tetragonal phase closed to 90% irrespectively of the surrounding atmosphere. The stabilisation of the tetragonal phase by grinding seems to be connected with the formation of tetragonal zirconia nuclei that cannot be observed by XRD. The crystallisation enthalpy measurements carried out by DSC support this conclusion.

  18. Effects of edge grinding and sealing on mechanical properties of machine damaged laminate composites

    NASA Astrophysics Data System (ADS)

    Asmatulu, Ramazan; Yeoh, Jason; Alarifi, Ibrahim M.; Alharbi, Abdulaziz

    2016-04-01

    Fiber reinforced composites have been utilized for a number of different applications, including aircraft, wind turbine, automobile, construction, manufacturing, and many other industries. During the fabrication, machining (waterjet, diamond and band saws) and assembly of these laminate composites, various edge and hole delamination, fiber pullout and other micro and nanocracks can be formed on the composite panels. The present study mainly focuses on the edge grinding and sealing of the machine damaged fiber reinforced composites, such as fiberglass, plain weave carbon fiber and unidirectional carbon fiber. The MTS tensile test results confirmed that the composite coupons from the grinding process usually produced better and consistent mechanical properties compared to the waterjet cut samples only. In addition to these studies, different types of high strength adhesives, such as EPON 828 and Loctite were applied on the edges of the prepared composite coupons and cured under vacuum. The mechanical tests conducted on these coupons indicated that the overall mechanical properties of the composite coupons were further improved. These processes can lower the labor costs on the edge treatment of the composites and useful for different industrial applications of fiber reinforced composites.

  19. Relationships Between Abrasive Wear, Hardness, and Surface Grinding Characteristics of Titanium-Based Metal Matrix Composites

    SciTech Connect

    Blau, Peter Julian; Jolly, Brian C

    2009-01-01

    The objective of this work was to support the development of grinding models for titanium metal-matrix composites (MMCs) by investigating possible relationships between their indentation hardness, low-stress belt abrasion, high-stress belt abrasion, and the surface grinding characteristics. Three Ti-based particulate composites were tested and compared with the popular titanium alloy Ti-6Al-4V. The three composites were a Ti-6Al-4V-based MMC with 5% TiB{sub 2} particles, a Ti-6Al-4V MMC with 10% TiC particles, and a Ti-6Al-4V/Ti-7.5%W binary alloy matrix that contained 7.5% TiC particles. Two types of belt abrasion tests were used: (a) a modified ASTM G164 low-stress loop abrasion test, and (b) a higher-stress test developed to quantify the grindability of ceramics. Results were correlated with G-ratios (ratio of stock removed to abrasives consumed) obtained from an instrumented surface grinder. Brinell hardness correlated better with abrasion characteristics than microindentation or scratch hardness. Wear volumes from low-stress and high-stress abrasive belt tests were related by a second-degree polynomial. Grindability numbers correlated with hard particle content but were also matrix-dependent.

  20. Pneumoconiosis in Makers of Artificial Grinding Wheels, Including a Case of Caplan's Syndrome*

    PubMed Central

    Posner, E.

    1960-01-01

    Mass miniature radiography surveys in a factory producing artificial grinding wheels detected cases of pneumoconiosis, mostly of the silicotic type. All cases were traced to the department where the so-called “bond” is prepared and mixed with the abrasive grains of carborundum and artificial corundum. This ceramic-vitrified bond, similar in composition to English general earthenware, contained until recently a significant proportion of free silica. The miniature film survey was followed up by an investigation on full-sized films, in which 92% of all workers in the bond department participated. The radiographs were subjected to dual independent viewing and it was found that 66% of the men who had worked in the bond department for more than 10 years showed radiological evidence of pneumoconiosis with a high proportion of progressive massive fibrosis (P.M.F.) Recently the amount of free silica in the ceramic bond has been reduced by the introduction of “frits” in place of powdered flint and part of the factory has been rebuilt and new methods of dust suppression and dust extraction have been introduced. One of the cases presented with the rheumatoid-pneumoconiotic syndrome, first described by Caplan. It is suggested that some of the cases of pneumoconiosis, attributed to carborundum, may be due to the binding materials of artificial grinding wheels. Images PMID:14434374