WorldWideScience

Sample records for cylindrical roller bearing

  1. Roller bearing geometry design

    Science.gov (United States)

    Savage, M.; Pinkston, B. H. W.

    1976-01-01

    A theory of kinematic stabilization of rolling cylinders is extended and applied to the design of cylindrical roller bearings. The kinematic stabilization mechanism puts a reverse skew into the rolling elements by changing the roller taper. Twelve basic bearing modification designs are identified amd modeled. Four have single transverse convex curvature in their rollers while eight have rollers which have compound transverse curvature made up of a central cylindrical band surrounded by symmetric bands with slope and transverse curvature. The bearing designs are modeled for restoring torque per unit axial displacement, contact stress capacity, and contact area including dynamic loading, misalignment sensitivity and roller proportion. Design programs are available which size the single transverse curvature roller designs for a series of roller slopes and load separations and which design the compound roller bearings for a series of slopes and transverse radii of curvature. The compound rollers are proportioned to have equal contact stresses and minimum size. Design examples are also given.

  2. Chaotic Dynamics of Cage Behavior in a High-Speed Cylindrical Roller Bearing

    Directory of Open Access Journals (Sweden)

    Long Chen

    2016-01-01

    Full Text Available This paper presents a mathematical model to investigate the nonlinear dynamic behavior of cage in high-speed cylindrical bearing. Variations of cage behavior due to varying cage eccentricity and cage guidance gap are observed. Hydrodynamic behavior in cage contacts is taken into consideration for a more realistic calculation of acting forces owing to high working speed. Analysis of real-time cage dynamic behavior on radial plane is carried out using chaos theory based on the theoretical and mathematical model established in the paper. The analytical results of this paper provide a solid foundation for designing and manufacturing of high-speed cylindrical roller bearing.

  3. On Calculation Methods and Results for Straight Cylindrical Roller Bearing Deflection, Stiffness, and Stress

    Science.gov (United States)

    Krantz, Timothy L.

    2011-01-01

    The purpose of this study was to assess some calculation methods for quantifying the relationships of bearing geometry, material properties, load, deflection, stiffness, and stress. The scope of the work was limited to two-dimensional modeling of straight cylindrical roller bearings. Preparations for studies of dynamic response of bearings with damaged surfaces motivated this work. Studies were selected to exercise and build confidence in the numerical tools. Three calculation methods were used in this work. Two of the methods were numerical solutions of the Hertz contact approach. The third method used was a combined finite element surface integral method. Example calculations were done for a single roller loaded between an inner and outer raceway for code verification. Next, a bearing with 13 rollers and all-steel construction was used as an example to do additional code verification, including an assessment of the leading order of accuracy of the finite element and surface integral method. Results from that study show that the method is at least first-order accurate. Those results also show that the contact grid refinement has a more significant influence on precision as compared to the finite element grid refinement. To explore the influence of material properties, the 13-roller bearing was modeled as made from Nitinol 60, a material with very different properties from steel and showing some potential for bearing applications. The codes were exercised to compare contact areas and stress levels for steel and Nitinol 60 bearings operating at equivalent power density. As a step toward modeling the dynamic response of bearings having surface damage, static analyses were completed to simulate a bearing with a spall or similar damage.

  4. KINEMATICS AND DYNAMICS MODELS OF CYLINDRICAL ROLLER BEARING OF RAILWAY TRANSPORT

    Directory of Open Access Journals (Sweden)

    A. V. Gaydamaka

    2014-05-01

    Full Text Available Purpose. Lack of kinematics models and imperfection of the known dynamics models of the roller bearings of railway rolling stock axle-boxes do not allow designing the optimal structure of bearing cages, providing the required service life and reliability of bearing units of wheel sets for cars and locomotives. The studies of kinematics and dynamics of roller bearings of axle boxes for cars and locomotives and modeling of their parts interaction to create the analytical method of bearing cages calculation are necessary. Methodology. This purpose has been achieved due to the modeling of kinematics of the ideal (without gaps and real (taking account the gaps, manufacturing and installation errors bearings, substantiation of the transfer mechanism of motion from the rollers to bearing cage, modeling the dynamics of rolling, research of interaction forces of the rollers with bearing cage. Findings. It is established that the kinematics of ideal bearing is determined by the contact deformations of the rollers and rings, when the kinematics of real bearing depends mainly on the side gaps in the windows of the bearing cage. On the basis of studies of the real bearing kinematics the dynamics models of the rollers and bearing cage interaction were constructed. The conducted studies of kinematics and dynamics of rolling bearings have changed our view of them as of the planetary mechanism, explained the reason of bearing cage loading, and confirmed the possibility of destruction during operation. Originality. It was first proposed a mechanism for motion transfer from the rollers to the bearing cage of roller bearings, consisting in that the side gap in the bearing cage window is reduced gradually multiple of the number of rollers of radial loading area according to the bearing cage motion. The models of roller bearing dynamics, which allow calculating the interaction forces of parts for all modes of operation, were improved. Practical value. Use of the

  5. Design algorithm for generatrix profile of cylindrical crowned rollers

    Directory of Open Access Journals (Sweden)

    Creţu Spiridon

    2017-01-01

    Full Text Available The cross-section of roller profile controls the pressure distribution in the contact area and radically affects the roller bearings basic dynamic load rating and rating lives. Today the most used roller profiles are the logarithmic profile and cylindrical-crowned (ZB profile. The logarithmic profile has a continuous evolution with no discontinuities till the intersection with the end fillet while ZB profile has two more discontinuities at the intersections points between the crowning circle and straight line generatrix. Using a semianalytical method, a numerical study has been carried out to find the optimum ZB profile for rollers incorporated in cylindrical rollers bearings. The basic reference rating life (L10_r has been used as optimization criterion.

  6. 49 CFR 230.103 - Tender roller bearing journal boxes.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Tender roller bearing journal boxes. 230.103... Locomotives and Tenders Running Gear § 230.103 Tender roller bearing journal boxes. Tender roller bearing journal boxes shall be maintained in a safe and suitable condition. ...

  7. 49 CFR 215.115 - Defective roller bearing.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Defective roller bearing. 215.115 Section 215.115... § 215.115 Defective roller bearing. (a) A railroad may not place or continue in service a car, if the car has— (1) A roller bearing that shows signs of having been overheated as evidenced by— (i...

  8. 49 CFR 215.117 - Defective roller bearing adapter.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Defective roller bearing adapter. 215.117 Section... Suspension System § 215.117 Defective roller bearing adapter. A railroad may not place or continue in service a car, if the car has a roller bearing adapter that is— (a) Cracked or broken; (b) Not in its design...

  9. Improvement of Railroad Roller Bearing Test Procedures & Development of Roller Bearing Diagnostic Techniques. Volume 2.

    Science.gov (United States)

    1982-04-01

    A comprehensive review of existing basic diagnostic techniques applicable to the railcar roller bearing defect and failure problem was made. Of the potentially feasible diagnostic techniques identified, high frequency vibration was selected for exper...

  10. Effect of Silicon Nitride Balls and Rollers on Rolling Bearing Life

    Science.gov (United States)

    Zaretsky, Erwin V.; Vlcek, Brian L.; Hendricks, Robert C.

    2005-01-01

    Three decades have passed since the introduction of silicon nitride rollers and balls into conventional rolling-element bearings. For a given applied load, the contact (Hertz) stress in a hybrid bearing will be higher than an all-steel rolling-element bearing. The silicon nitride rolling-element life as well as the lives of the steel races were used to determine the resultant bearing life of both hybrid and all-steel bearings. Life factors were determined and reported for hybrid bearings. Under nominal operating speeds, the resultant calculated lives of the deep-groove, angular-contact, and cylindrical roller hybrid bearings with races made of post-1960 bearing steel increased by factors of 3.7, 3.2, and 5.5, respectively, from those calculated using the Lundberg-Palmgren equations. An all-steel bearing under the same load will have a longer life than the equivalent hybrid bearing under the same conditions. Under these conditions, hybrid bearings are predicted to have a lower fatigue life than all-steel bearings by 58 percent for deep-groove bearings, 41 percent for angular-contact bearings, and 28 percent for cylindrical roller bearings.

  11. A Optimal Dimension Parameters Design of Needle Roller Bearings Considering Multi Factors Affecting Life

    Science.gov (United States)

    Bai, XiaoBo; Li, Bo

    2017-12-01

    Taking into many influencing factors, a Needle Roller Bearings life calculation model was established using the Influence coefficient method and ISO formula. Take this model as the optimization objective function, some optimization variables were determined, and these variables were added constraint conditions. Using dynamic nonlinear strategy to improve the inertia weight, the arccosine strategy to adjust the learning factor, function constraints was solved by the methods of ensure particle legitimacy. Nonlinear optimization design of cylindrical roller bearings was realized by Improved Particle Swarm Algorithm. The proposed method of bearing design was verified effective by test of the optimization results.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-06-30

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

  13. Depreciation of bearing blocks of rollers of roller conveyers of rolling mills

    Science.gov (United States)

    Artiukh, Viktor; Belyaev, Michael; Ignatovich, Igor; Miloradova, Nadezda

    2017-10-01

    Essential increase in functional durability of a node of a roller of the roller conveyer of the rolling mill by the rational choice of parameters of the small-size shock-absorber (buffer adapter) is shown. At the same time dimensions of a node don’t change, costs of reconstruction are small. The possibility of management of loadings in a bearing node without change of technology parameters of the process which is carried out by the rolling mill is confirmed.

  14. 48 CFR 252.225-7016 - Restriction on acquisition of ball and roller bearings.

    Science.gov (United States)

    2010-10-01

    ... of ball and roller bearings. 252.225-7016 Section 252.225-7016 Federal Acquisition Regulations System... and roller bearings. As prescribed in 225.7009-5, use the following clause: Restriction on Acquisition of Ball and Roller Bearings (MAR 2006) (a) Definitions. As used in this clause' (1) Bearing...

  15. 48 CFR 225.7009 - Restriction on ball and roller bearings.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Restriction on ball and roller bearings. 225.7009 Section 225.7009 Federal Acquisition Regulations System DEFENSE ACQUISITION... roller bearings. ...

  16. Simple and Versatile Dynamic Model of Spherical Roller Bearing

    Directory of Open Access Journals (Sweden)

    Behnam Ghalamchi

    2013-01-01

    Full Text Available Rolling element bearings are essential components of rotating machinery. The spherical roller bearing (SRB is one variant witnessing increasing use because it is self-aligning and can support high loads. It is becoming increasingly important to understand how the SRB responds dynamically under a variety of conditions. This study introduces a computationally efficient, three-degree-of-freedom, SRB model that was developed to predict the transient dynamic behaviors of a rotor-SRB system. In the model, bearing forces and deflections were calculated as a function of contact deformation and bearing geometry parameters according to the nonlinear Hertzian contact theory. The results reveal how some of the more important parameters, such as diametral clearance, the number of rollers, and osculation number, influence ultimate bearing performance. One pair of calculations looked at bearing displacement with respect to time for two separate arrangements of the caged side-by-side roller arrays, when they are aligned and when they are staggered. As theory suggests, significantly lower displacement variations were predicted for the staggered arrangement. Following model verification, a numerical simulation was carried out successfully for a full rotor-bearing system to demonstrate the application of this newly developed SRB model in a typical real world analysis.

  17. Roller Bearing Monitoring by New Subspace-Based Damage Indicator

    Directory of Open Access Journals (Sweden)

    G. Gautier

    2015-01-01

    Full Text Available A frequency-band subspace-based damage identification method for fault diagnosis in roller bearings is presented. Subspace-based damage indicators are obtained by filtering the vibration data in the frequency range where damage is likely to occur, that is, around the bearing characteristic frequencies. The proposed method is validated by considering simulated data of a damaged bearing. Also, an experimental case is considered which focuses on collecting the vibration data issued from a run-to-failure test. It is shown that the proposed method can detect bearing defects and, as such, it appears to be an efficient tool for diagnosis purpose.

  18. Kinematic correction for roller skewing

    Science.gov (United States)

    Savage, M.; Loewenthal, S. H.

    1980-01-01

    A theory of kinematic stabilization of rolling cylinders is developed for high-speed cylindrical roller bearings. This stabilization requires race and roller crowning to product changes in the rolling geometry as the roller shifts axially. These changes put a reverse skew in the rolling elements by changing the rolling taper. Twelve basic possible bearing modifications are identified in this paper. Four have single transverse convex curvature in the rollers while eight have rollers with compound transverse curvature composed of a central cylindrical band of constant radius surrounded by symmetric bands with both slope and transverse curvature.

  19. Analytical evaluation of the roller bearing service life

    Directory of Open Access Journals (Sweden)

    Antsupov Aleksey

    2017-01-01

    Full Text Available An analytical method has been developed for the design evaluation of the service life of roller bearings by the criterion of contact endurance of elements that does not require carrying out the experimental studies. It is based on the kinetic approach to the description of the solids destruction process and the theory of parametric reliability of machine parts. In contradistinction to the standard empirical dependence, which is currently used, the method allows one to take into account the effect of the material properties, and basic design and operational parameters on the service life. The results of the theoretical studies of the service life of roller bearing No. 212 (DIN 5412 T1 are presented for the quantitative assessment of this effect. They showed that the temperature-force loading conditions or material properties that were not taken into account might result in the prediction error of 1.5 or more times.

  20. Avoiding Electroerosion in roller bearings; Elektroerosion in Waelzlagern vermeiden

    Energy Technology Data Exchange (ETDEWEB)

    Preisinger, G.; Groeschl, M. [Inst. fuer Allgemeine Physik der TU Wien (Austria); Koettritsch, H. [SKF Oesterreich AG, Steyr (Austria)

    2001-12-17

    Roller bearings in electric motors and generators can be exposed to passage of current, which failes not only components, but also changes lubricants. The erosion can be avoided by isolation layers and optimized frequency converters. [German] Waelzlager in Elektromotoren und Generatoren koennen Stromdurchgang ausgesetzt sein, der nicht nur die Teile schaedigt, sondern auch den Schmierstoff veraendert. Die Schaeden sind nicht nur auf Metallteile begrenzt. Abhilfe bieten Isolationsschichten und optimierte Frequenzumrichter. (orig.)

  1. Vibratory synchronization transmission of a cylindrical roller in a vibrating mechanical system excited by two exciters

    Science.gov (United States)

    Zhang, Xueliang; Wen, Bangchun; Zhao, Chunyu

    2017-11-01

    In present work vibratory synchronization transmission (VST) of a cylindrical roller with dry friction in a vibrating mechanical system excited by two exciters, is studied. Using the average method, the criterion of implementing synchronization of two exciters and that of ensuring VST of a roller, are achieved. The criterion of stability of the synchronous states satisfies the Routh-Hurwitz principle. The influences of the structural parameters of the system to synchronization and stability, are discussed numerically, which can be served as the theoretical foundation for engineering designs. An experiment is carried out, which approximately verify the validity of the theoretical and numerical results, as well as the feasibility of the method used. Utilizing the VST theory of a roller, some types of vibrating crushing or grinding equipments, etc., can be designed.

  2. Fast EEMD Based AM-Correntropy Matrix and Its Application on Roller Bearing Fault Diagnosis

    Directory of Open Access Journals (Sweden)

    Yunxiao Fu

    2016-06-01

    Full Text Available Roller bearing plays a significant role in industrial sectors. To improve the ability of roller bearing fault diagnosis under multi-rotating situation, this paper proposes a novel roller bearing fault characteristic: the Amplitude Modulation (AM based correntropy extracted from the Intrinsic Mode Functions (IMFs, which are decomposed by Fast Ensemble Empirical mode decomposition (FEEMD and employ Least Square Support Vector Machine (LSSVM to implement intelligent fault identification. Firstly, the roller bearing vibration acceleration signal is decomposed by FEEMD to extract IMFs. Secondly, IMF correntropy matrix (IMFCM as the fault feature matrix is calculated from the AM-correntropy model of the primary vibration signal and IMFs. Furthermore, depending on LSSVM, the fault identification results of the roller bearing are obtained. Through the bearing identification experiments in stationary rotating conditions, it was verified that IMFCM generates more stable and higher diagnosis accuracy than conventional fault features such as energy moment, fuzzy entropy, and spectral kurtosis. Additionally, it proves that IMFCM has more diagnosis robustness than conventional fault features under cross-mixed roller bearing operating conditions. The diagnosis accuracy was more than 84% for the cross-mixed operating condition, which is much higher than the traditional features. In conclusion, it was proven that FEEMD-IMFCM-LSSVM is a reliable technology for roller bearing fault diagnosis under the constant or multi-positioned operating conditions, and as such, it possesses potential prospects for a broad application of uses.

  3. High Capacity cylinder roller bearing; High Capacity Zylinderrollenlager. Ein vollrolliges Lager mit Kaefig

    Energy Technology Data Exchange (ETDEWEB)

    Reichert, J.; Baum, J. [SKF, Schweinfurt (Germany)

    2007-07-15

    The high capacity cylinder roller bearing is an example for continuous development of SKF products and does an effective contribution to increase operational safety and offers the possibility to reduce weight and compact design. (GL)

  4. Prevention of Roller Bearing-Initiated Burnoffs in Railroad Freight Car Journals

    Science.gov (United States)

    1979-01-01

    The objective of this program was to determine the technical feasibility and cost effectiveness of constructing three separate devices for the prevention of catastrophic roller bearing-initiated, railroad journal failure. 1. Construction of a low cos...

  5. Documentation of roller-bearing effect on butterfly inspired grooves

    Science.gov (United States)

    Gautam, Sashank; Lang, Amy

    2017-11-01

    Butterfly wings are covered with scales in a roof shingle pattern which align together to form grooves. The increase or decrease of laminar friction drag depends on the flow orientation to the scales. Flow in the longitudinal direction to the grooves encounters increased surface area which increases the friction drag. However, in the transverse direction, for low Re laminar flow, a single vortex is formed inside each groove and is predicted to remain stable due to the very low Re of the flow in each cavity. These embedded vortices act as roller bearings to the flow above, such that the fluid from the outer boundary layer does not mix with fluid inside the cavities. This leads to a reduction of skin friction drag when compared to a smooth surface. When the cavity flow Re is increased beyond a critical point, the vortex becomes unstable and the low-momentum fluid in the grooves mixes with the outer boundary layer flow, increasing the drag. The objective of this experiment is to determine the critical Re where the embedded vortex transitions from a stable to an unstable state using DPIV. Subsequently, for steady vortex conditions, a comparison of skin friction drag between the grooved and flat plate can show that the butterfly scaled surface can result in sub-laminar friction drag. The National Science Foundation (Grant No. 1335848).

  6. Investigating possible use of roller bearings made of plastic in belt conveyor idlers

    Energy Technology Data Exchange (ETDEWEB)

    Grzeszek, A

    1979-05-01

    This paper presents results of laboratory and operational tests of roller bearings made of polyamide in belt conveyor idlers. During operational tests the conveyor was inclined to one side so the load on individual bearings varied and the bearings were also covered with dust and dirt. The tests show that the first failures of the plastic bearings took place after 3 months but some of the bearings were in operation one year without failures. All the failures were caused by wear of the bearing due to dust and dirt on their sliding surface. Increased friction resulted in higher temperatures which deformed the bearings. The tests showed that the bearings which were not dirty operated without failure. It is concluded that the plastic-made roller bearings cannot be used under conditions of brown coal surface mines as these mines are characterized by intense dustfall and by dirt which would increase friction in the bearings. (In Polish)

  7. Performance Analysis of Functionally Graded Coatings in Contact with Cylindrical Rollers

    Directory of Open Access Journals (Sweden)

    Reza Jahedi

    2015-01-01

    Full Text Available This work presents finite element analysis (FEA and results for rolling contact of a cylindrical roller on an elastic substrate coated by functionally graded material (FGM. The rolling process and the graded coating material property and layers arrangement are modeled using finite element codes which lead to a new methodology. This novel methodology provides a trend in determining surface contact stresses, deformations, contact zones, and energy dissipation through the contact area. Effects of stiffness ratio, friction, and exponentially variation of material property on the contact stresses and deformations are studied. Some of the results are verified with analytical solutions. The study results may be beneficial in graded coated cylindrical components analysis against rolling contact failure and wear.

  8. Improvement of Roller Bearing Diagnosis with Unlabeled Data Using Cut Edge Weight Confidence Based Tritraining

    Directory of Open Access Journals (Sweden)

    Wei-Li Qin

    2016-01-01

    Full Text Available Roller bearings are one of the most commonly used components in rotational machines. The fault diagnosis of roller bearings thus plays an important role in ensuring the safe functioning of the mechanical systems. However, in most cases of bearing fault diagnosis, there are limited number of labeled data to achieve a proper fault diagnosis. Therefore, exploiting unlabeled data plus few labeled data, this paper proposed a roller bearing fault diagnosis method based on tritraining to improve roller bearing diagnosis performance. To overcome the noise brought by wrong labeling into the classifiers training process, the cut edge weight confidence is introduced into the diagnosis framework. Besides a small trick called suspect principle is adopted to avoid overfitting problem. The proposed method is validated in two independent roller bearing fault experiment vibrational signals that both include three types of faults: inner-ring fault, outer-ring fault, and rolling element fault. The results demonstrate the desirable diagnostic performance improvement by the proposed method in the extreme situation where there is only limited number of labeled data.

  9. Nanocrystalline, superhard, ductile ceramic coatings for roller-cone bit bearings

    Energy Technology Data Exchange (ETDEWEB)

    Namavar, F.; Colter, P.; Karimy, H. [Spire Corp., Bedford, MA (United States)] [and others

    1997-12-31

    The established method for construction of roller bits utilizes carburized steel, frequently with inserted metal bearing surfaces. This construction provides the necessary surface hardness while maintaining other desirable properties in the core. Protective coatings are a logical development where enhanced hardness, wear resistance, corrosion resistance, and surface properties are required. The wear properties of geothermal roller-cone bit bearings could be further improved by application of protective ceramic hard coatings consisting of nanometer-sized crystallites. Nanocrystalline protective coatings provide the required combination of hardness and toughness which has not been available thus far using traditional ceramics having larger grains. Increased durability of roller-cone bit bearings will ultimately reduce the cost of drilling geothermal wells through increased durability.

  10. 77 FR 50716 - Tapered Roller Bearings From China

    Science.gov (United States)

    2012-08-22

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-344 (Third Review)] Tapered Roller..., the United States International Trade Commission (Commission) determines, pursuant to section 751(c... notice in the Office of the Secretary, U.S. International Trade Commission, Washington, DC, and by...

  11. Adaptive Technology Application for Vibration-Based Diagnostics of Roller Bearings on Industrial Plants

    Directory of Open Access Journals (Sweden)

    Mironov Aleksey

    2014-09-01

    Full Text Available Roller bearings are widely used in equipment of different applications; therefore, the issues related to the assessment of bearing technical state and localization of bearing faults are quite important and relevant. The reason is that technical state of a bearing is a critical component, which determines efficiency of a mechanism or equipment. For bearings inspection and diagnostics, various methods of vibration-based diagnostics are used. The adaptive technology for vibration-based diagnostics developed in „D un D centrs” is an effective tool for evaluation of technical state of bearings in operation compared to the existing SKF method.

  12. A Roller Bearing Fault Diagnosis Method Based on LCD Energy Entropy and ACROA-SVM

    Directory of Open Access Journals (Sweden)

    HungLinh Ao

    2014-01-01

    Full Text Available This study investigates a novel method for roller bearing fault diagnosis based on local characteristic-scale decomposition (LCD energy entropy, together with a support vector machine designed using an Artificial Chemical Reaction Optimisation Algorithm, referred to as an ACROA-SVM. First, the original acceleration vibration signals are decomposed into intrinsic scale components (ISCs. Second, the concept of LCD energy entropy is introduced. Third, the energy features extracted from a number of ISCs that contain the most dominant fault information serve as input vectors for the support vector machine classifier. Finally, the ACROA-SVM classifier is proposed to recognize the faulty roller bearing pattern. The analysis of roller bearing signals with inner-race and outer-race faults shows that the diagnostic approach based on the ACROA-SVM and using LCD to extract the energy levels of the various frequency bands as features can identify roller bearing fault patterns accurately and effectively. The proposed method is superior to approaches based on Empirical Mode Decomposition method and requires less time.

  13. Evaluation of ball and roller bearings restored by grinding

    Science.gov (United States)

    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.

  14. Intelligence diagnosis method for roller bearings using features of AE signal

    International Nuclear Information System (INIS)

    Pan, J; Wang, H Q; Wang, F; Yang, J F; Liu, W B

    2012-01-01

    Rolling bearings are important components in rotating machines, which are wildly used in industrial production. The fault diagnosis technology plays a very important role for quality and life of machines. Based on symptom parameters of acoustic emission (AE) signals, this paper presents an intelligent diagnosis method for roller bearings using the principal component analysis, rough sets, and BP neural network to detect faults and distinguish fault types. The principal component analysis and the rough sets algorithm are used to reduce details of time-domain symptom parameters for training the BP neural network. The BP neural network, which is used for condition diagnosis of roller bearings, can obtain good convergence using the symptom parameters acquired by the principal component analysis and the rough sets during learning, and automatically distinguish fault types during diagnosing. Practical examples are provided to verify the efficiency of the proposed method.

  15. Hydrodynamic sliding bearings vs. roller bearings. Segmented sliding bearings for higher rotational speed; Hydrodynamische Gleitlager versus Waelzlager. Segmentgleitlager fuer hoehere Drehzahlen

    Energy Technology Data Exchange (ETDEWEB)

    Hagenhoff, M.; Sauer, M. [Main-Metall-Giesserei Fritz Schorr GmbH und Co. KG, Altenglan (Germany)

    2004-10-01

    Hydrodynamic sliding bearings are considered only in cases when roller bearings reach their speed limits and there is no other solution. However, this view neglects the fact that there are modern, optimised sliding bearings which have more advantages over roller bearings than should be expected. Many producers of sliding bearings also have computer programs enabling them to offer customised solutions, i.e. optimal adaptation of the bearings to their specific operating conditions. (orig.) [German] Hydrodynamische Gleitlager werden oft erst dann in Betracht gezogen, wenn man an die Drehzahlgrenzen von Waelzlagern stoesst und keine andere sinnvolle Alternative mehr in Frage kommt. Dabei uebersieht man leicht, dass es moderne, optimierte Gleitlagerkonstruktionen gibt, die weitaus haeufiger ihre Staerken im Vergleich zu Waelzlagern ausspielen koennen als zunaechst vermutet. Viele Gleitlagerhersteller haben zudem heute Berechnungsprogramme zur Verfuegung, die eine optimale Anpassung der Lager an die speziellen Betriebsbedingungen erlauben. (orig.)

  16. Bearing life in contaminated oil and oil passing into bearing for tapered roller bearing; Ensui koro jikuuke ni okeru ibutsu yuchu deno jumyo to kantsu yuryo

    Energy Technology Data Exchange (ETDEWEB)

    Asai, Y; Oshima, H; Sakamoto, K [Koyo Seiko Co. Ltd., Osaka (Japan)

    1997-10-01

    In this paper a relationship between depth of dents, area of dents gathered and bearing life has been investigated for tapered roller bearings used in differential gear case. It is effective for the longer bearing life to reduce hard particles of Fe especially among several contaminations existing in the gear case. It is also effective to make oil level lower in the case from the view point for reduction of number of dents. 8 refs., 8 figs., 4 tabs.

  17. Gearbox Reliability Collaborative High Speed Shaft Tapered Roller Bearing Calibration

    Energy Technology Data Exchange (ETDEWEB)

    Keller, J.; Guo, Y.; McNiff, B.

    2013-10-01

    The National Renewable Energy Laboratory (NREL) Gearbox Reliability Collaborative (GRC) is a project investigating gearbox reliability primarily through testing and modeling. Previous dynamometer testing focused upon acquiring measurements in the planetary section of the test gearbox. Prior to these tests, the strain gages installed on the planetary bearings were calibrated in a load frame.

  18. Compressed sensing of roller bearing fault based on multiple down-sampling strategy

    International Nuclear Information System (INIS)

    Wang, Huaqing; Ke, Yanliang; Luo, Ganggang; Tang, Gang

    2016-01-01

    Roller bearings are essential components of rotating machinery and are often exposed to complex operating conditions, which can easily lead to their failures. Thus, to ensure normal production and the safety of machine operators, it is essential to detect the failures as soon as possible. However, it is a major challenge to maintain a balance between detection efficiency and big data acquisition given the limitations of sampling theory. To overcome these limitations, we try to preserve the information pertaining to roller bearing failures using a sampling rate far below the Nyquist sampling rate, which can ease the pressure generated by the large-scale data. The big data of a faulty roller bearing’s vibration signals is firstly reduced by a down-sample strategy while preserving the fault features by selecting peaks to represent the data segments in time domain. However, a problem arises in that the fault features may be weaker than before, since the noise may be mistaken for the peaks when the noise is stronger than the vibration signals, which makes the fault features unable to be extracted by commonly-used envelope analysis. Here we employ compressive sensing theory to overcome this problem, which can make a signal enhancement and reduce the sample sizes further. Moreover, it is capable of detecting fault features from a small number of samples based on orthogonal matching pursuit approach, which can overcome the shortcomings of the multiple down-sample algorithm. Experimental results validate the effectiveness of the proposed technique in detecting roller bearing faults. (paper)

  19. Compressed sensing of roller bearing fault based on multiple down-sampling strategy

    Science.gov (United States)

    Wang, Huaqing; Ke, Yanliang; Luo, Ganggang; Tang, Gang

    2016-02-01

    Roller bearings are essential components of rotating machinery and are often exposed to complex operating conditions, which can easily lead to their failures. Thus, to ensure normal production and the safety of machine operators, it is essential to detect the failures as soon as possible. However, it is a major challenge to maintain a balance between detection efficiency and big data acquisition given the limitations of sampling theory. To overcome these limitations, we try to preserve the information pertaining to roller bearing failures using a sampling rate far below the Nyquist sampling rate, which can ease the pressure generated by the large-scale data. The big data of a faulty roller bearing’s vibration signals is firstly reduced by a down-sample strategy while preserving the fault features by selecting peaks to represent the data segments in time domain. However, a problem arises in that the fault features may be weaker than before, since the noise may be mistaken for the peaks when the noise is stronger than the vibration signals, which makes the fault features unable to be extracted by commonly-used envelope analysis. Here we employ compressive sensing theory to overcome this problem, which can make a signal enhancement and reduce the sample sizes further. Moreover, it is capable of detecting fault features from a small number of samples based on orthogonal matching pursuit approach, which can overcome the shortcomings of the multiple down-sample algorithm. Experimental results validate the effectiveness of the proposed technique in detecting roller bearing faults.

  20. Compressive Sensing of Roller Bearing Faults via Harmonic Detection from Under-Sampled Vibration Signals.

    Science.gov (United States)

    Tang, Gang; Hou, Wei; Wang, Huaqing; Luo, Ganggang; Ma, Jianwei

    2015-10-09

    The Shannon sampling principle requires substantial amounts of data to ensure the accuracy of on-line monitoring of roller bearing fault signals. Challenges are often encountered as a result of the cumbersome data monitoring, thus a novel method focused on compressed vibration signals for detecting roller bearing faults is developed in this study. Considering that harmonics often represent the fault characteristic frequencies in vibration signals, a compressive sensing frame of characteristic harmonics is proposed to detect bearing faults. A compressed vibration signal is first acquired from a sensing matrix with information preserved through a well-designed sampling strategy. A reconstruction process of the under-sampled vibration signal is then pursued as attempts are conducted to detect the characteristic harmonics from sparse measurements through a compressive matching pursuit strategy. In the proposed method bearing fault features depend on the existence of characteristic harmonics, as typically detected directly from compressed data far before reconstruction completion. The process of sampling and detection may then be performed simultaneously without complete recovery of the under-sampled signals. The effectiveness of the proposed method is validated by simulations and experiments.

  1. 78 FR 40692 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the People's Republic of...

    Science.gov (United States)

    2013-07-08

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-570-601] Tapered Roller Bearings and..., International Trade Administration, Department of Commerce. SUMMARY: The Department of Commerce (Department) is... Department selected one mandatory respondent for individual examination (i.e., Changshan Peer Bearing Co. Ltd...

  2. Vibration analysis of paper machine's asymmetric tube roll supported by spherical roller bearings

    Science.gov (United States)

    Heikkinen, Janne E.; Ghalamchi, Behnam; Viitala, Raine; Sopanen, Jussi; Juhanko, Jari; Mikkola, Aki; Kuosmanen, Petri

    2018-05-01

    This paper presents a simulation method that is used to study subcritical vibrations of a tube roll in a paper machine. This study employs asymmetric 3D beam elements based on the Timoshenko beam theory. An asymmetric beam model accounts for varying stiffness and mass distributions. Additionally, a detailed rolling element bearing model defines the excitations arising from the set of spherical roller bearings at both ends of the rotor. The results obtained from the simulation model are compared against the results from the measurements. The results indicate that the waviness of the bearing rolling surfaces contributes significantly to the subcritical vibrations while the asymmetric properties of the tube roll have only a fractional effect on the studied vibrations.

  3. Degradation Assessment and Fault Diagnosis for Roller Bearing Based on AR Model and Fuzzy Cluster Analysis

    Directory of Open Access Journals (Sweden)

    Lingli Jiang

    2011-01-01

    Full Text Available This paper proposes a new approach combining autoregressive (AR model and fuzzy cluster analysis for bearing fault diagnosis and degradation assessment. AR model is an effective approach to extract the fault feature, and is generally applied to stationary signals. However, the fault vibration signals of a roller bearing are non-stationary and non-Gaussian. Aiming at this problem, the set of parameters of the AR model is estimated based on higher-order cumulants. Consequently, the AR parameters are taken as the feature vectors, and fuzzy cluster analysis is applied to perform classification and pattern recognition. Experiments analysis results show that the proposed method can be used to identify various types and severities of fault bearings. This study is significant for non-stationary and non-Gaussian signal analysis, fault diagnosis and degradation assessment.

  4. Micromechanical study of the effect of inclusions on fatigue failure in a roller bearing

    DEFF Research Database (Denmark)

    Cerullo, Michele; Tvergaard, Viggo

    2015-01-01

    model containing a single inclusion, using the approximation of a 2D plane strain numerical analysis. The Dang Van multiaxial fatigue criterion is used for the local stresses in the matrix material, to ensure that the stresses remain within the fatigue limit. The matrix material is taken to be one...... of the most commonly used bearing steels, AISI 52100, and two different types of inclusions are considered. The macroscopic stress histories applied correspond to either a Hertzian or an elastohydrodynamic (EHL) contact pressure distribution under the rollers. Findings - The paper shows that sub...

  5. A Sparsity-Promoted Decomposition for Compressed Fault Diagnosis of Roller Bearings

    Directory of Open Access Journals (Sweden)

    Huaqing Wang

    2016-09-01

    Full Text Available The traditional approaches for condition monitoring of roller bearings are almost always achieved under Shannon sampling theorem conditions, leading to a big-data problem. The compressed sensing (CS theory provides a new solution to the big-data problem. However, the vibration signals are insufficiently sparse and it is difficult to achieve sparsity using the conventional techniques, which impedes the application of CS theory. Therefore, it is of great significance to promote the sparsity when applying the CS theory to fault diagnosis of roller bearings. To increase the sparsity of vibration signals, a sparsity-promoted method called the tunable Q-factor wavelet transform based on decomposing the analyzed signals into transient impact components and high oscillation components is utilized in this work. The former become sparser than the raw signals with noise eliminated, whereas the latter include noise. Thus, the decomposed transient impact components replace the original signals for analysis. The CS theory is applied to extract the fault features without complete reconstruction, which means that the reconstruction can be completed when the components with interested frequencies are detected and the fault diagnosis can be achieved during the reconstruction procedure. The application cases prove that the CS theory assisted by the tunable Q-factor wavelet transform can successfully extract the fault features from the compressed samples.

  6. Mechanical analysis and optimisation of large and highly-loaded bearing rollers For the "Riesenrad" Ion Gantry

    CERN Document Server

    Reimoser, S A

    2000-01-01

    A carbon ion gantry would allow the irradiation of cancer patients with carbon ions from any direction in space best suited for therapy. Till today, such a machine has not been built due to the expected size, mass and cost. A novel design, called "Riesenrad" ion gantry, promises to provide a competitive solution. The central part of the Riesenrad, which can rotate ± 90°, is supported (statically determinate) on pendular bearing units with two rollers each. High precision requirements for the structure rule out any plastic deformations in the area of contact. The present report describes the design of the highly-loaded rollers. In order to achieve a large contact area and a uniform distribution of contact stresses, a "barrel shape" for the rollers is proposed. An analysis using the finite element method (FEM) was performed to optimise the roller design, namely to establish the required crown roll (camber radius).

  7. A hybrid approach to fault diagnosis of roller bearings under variable speed conditions

    Science.gov (United States)

    Wang, Yanxue; Yang, Lin; Xiang, Jiawei; Yang, Jianwei; He, Shuilong

    2017-12-01

    Rolling element bearings are one of the main elements in rotating machines, whose failure may lead to a fatal breakdown and significant economic losses. Conventional vibration-based diagnostic methods are based on the stationary assumption, thus they are not applicable to the diagnosis of bearings working under varying speeds. This constraint limits the bearing diagnosis to the industrial application significantly. A hybrid approach to fault diagnosis of roller bearings under variable speed conditions is proposed in this work, based on computed order tracking (COT) and variational mode decomposition (VMD)-based time frequency representation (VTFR). COT is utilized to resample the non-stationary vibration signal in the angular domain, while VMD is used to decompose the resampled signal into a number of band-limited intrinsic mode functions (BLIMFs). A VTFR is then constructed based on the estimated instantaneous frequency and instantaneous amplitude of each BLIMF. Moreover, the Gini index and time-frequency kurtosis are both proposed to quantitatively measure the sparsity and concentration measurement of time-frequency representation, respectively. The effectiveness of the VTFR for extracting nonlinear components has been verified by a bat signal. Results of this numerical simulation also show the sparsity and concentration of the VTFR are better than those of short-time Fourier transform, continuous wavelet transform, Hilbert-Huang transform and Wigner-Ville distribution techniques. Several experimental results have further demonstrated that the proposed method can well detect bearing faults under variable speed conditions.

  8. 78 FR 45912 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the People's Republic of...

    Science.gov (United States)

    2013-07-30

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-570-601] Tapered Roller Bearings and..., International Trade Administration, U.S. Department of Commerce, 14th Street and Constitution Avenue NW... Duty New Shipper Review AGENCY: Import Administration, International Trade Administration, Department...

  9. Application of Dang Van criterion to rolling contact fatigue in wind turbine roller bearings under elastohydrodynamic lubrication conditions

    DEFF Research Database (Denmark)

    Cerullo, Michele

    2014-01-01

    classic Hertzian and elastohydrodynamic lubrication theories have been used to model the pressure distribution acting on the inner raceway and results are compared according to the Dang Van multiaxial fatigue criterion. The contact on the bearing raceway is simulated by substituting the roller...

  10. 77 FR 2031 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the People's Republic of...

    Science.gov (United States)

    2012-01-13

    ... Parts Thereof, Finished and Unfinished From the People's Republic of China: Extension of the Time Limit..., International Trade Administration, U.S. Department of Commerce, 14th Street and Constitution Avenue NW..., finished and unfinished from the People's Republic of China. See Tapered Roller Bearings and Parts Thereof...

  11. 76 FR 76143 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the People's Republic of...

    Science.gov (United States)

    2011-12-06

    ..., the United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service... manufacturing of tapered roller bearings and parts thereof in the United States, also notified the Department... manufacturing the domestic like product, and therefore, is an interested party pursuant to section 771(9)(D) of...

  12. Sequential Fuzzy Diagnosis Method for Motor Roller Bearing in Variable Operating Conditions Based on Vibration Analysis

    Directory of Open Access Journals (Sweden)

    Yi Cao

    2013-06-01

    Full Text Available A novel intelligent fault diagnosis method for motor roller bearings which operate under unsteady rotating speed and load is proposed in this paper. The pseudo Wigner-Ville distribution (PWVD and the relative crossing information (RCI methods are used for extracting the feature spectra from the non-stationary vibration signal measured for condition diagnosis. The RCI is used to automatically extract the feature spectrum from the time-frequency distribution of the vibration signal. The extracted feature spectrum is instantaneous, and not correlated with the rotation speed and load. By using the ant colony optimization (ACO clustering algorithm, the synthesizing symptom parameters (SSP for condition diagnosis are obtained. The experimental results shows that the diagnostic sensitivity of the SSP is higher than original symptom parameter (SP, and the SSP can sensitively reflect the characteristics of the feature spectrum for precise condition diagnosis. Finally, a fuzzy diagnosis method based on sequential inference and possibility theory is also proposed, by which the conditions of the machine can be identified sequentially as well.

  13. Gearbox Reliability Collaborative Gearbox 3 Planet Bearing Calibration

    Energy Technology Data Exchange (ETDEWEB)

    Keller, Jonathan [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2017-03-24

    The Gearbox Reliability Collaborative gearbox was redesigned to improve its load-sharing characteristics and predicted fatigue life. The most important aspect of the redesign was to replace the cylindrical roller bearings with preloaded tapered roller bearings in the planetary section. Similar to previous work, the strain gages installed on the planet tapered roller bearings were calibrated in a load frame. This report describes the calibration tests and provides the factors necessary to convert the measured units from dynamometer testing to bearing loads, suitable for comparison to engineering models.

  14. Natural roller bearing fault detection by angular measurement of true instantaneous angular speed

    Science.gov (United States)

    Renaudin, L.; Bonnardot, F.; Musy, O.; Doray, J. B.; Rémond, D.

    2010-10-01

    The challenge in many production activities involving large mechanical devices like power transmissions consists in reducing the machine downtime, in managing repairs and in improving operating time. Most online monitoring systems are based on conventional vibration measurement devices for gear transmissions or bearings in mechanical components. In this paper, we propose an alternative way of bearing condition monitoring based on the instantaneous angular speed measurement. By the help of a large experimental investigation on two different applications, we prove that localized faults like pitting in bearing generate small angular speed fluctuations which are measurable with optical or magnetic encoders. We also emphasize the benefits of measuring instantaneous angular speed with the pulse timing method through an implicit angular sampling which ensures insensitivity to speed fluctuation. A wide range of operating conditions have been tested for the two applications with varying speed, load, external excitations, gear ratio, etc. The tests performed on an automotive gearbox or on actual operating vehicle wheels also establish the robustness of the proposed methodology. By the means of a conventional Fourier transform, angular frequency channels kinematically related to the fault periodicity show significant magnitude differences related to the damage severity. Sideband effects are evidently seen when the fault is located on rotating parts of the bearing due to load modulation. Additionally, slip effects are also suspected to be at the origin of enlargement of spectrum peaks in the case of double row bearings loaded in a pure radial direction.

  15. Defect diagnosis and root cause analysis for thrust roller bearing of centrifugal charging pump

    International Nuclear Information System (INIS)

    Guo Yi

    2012-01-01

    The centrifugal charging pump is one of the most important equipment for Nuclear power plant which requires very high reliability, during C9 fuel-cycle, the continuous high level vibration alarm happened on the centrifugal charging pump B, we diagnosed its faults correctly and selected the right operation mode and right time to dismantle it which ensure the safety and economic benefits of Nuclear power plant, and through deeply analysis the root causes of thrust bearing defaults, we can learn much from it especially for the diagnosis and analysis to the bearing faults which is common for rotating equipment. (author)

  16. 75 FR 76297 - Defense Federal Acquisition Regulation Supplement; Restriction on Ball and Roller Bearings (DFARS...

    Science.gov (United States)

    2010-12-08

    ... does not have enough market leverage for it to be in the business interest of the manufacturers and... reason for changing the rule is statutory change. 10 U.S.C. 2534(a)(5) is no longer in effect because... Government leverage with regard to acquisition of commercial bearings. The Government continues to issue more...

  17. Sub-surface Fatigue Crack Growth at Alumina Inclusions in AISI 52100 Roller Bearings

    DEFF Research Database (Denmark)

    Cerullo, Michele

    2014-01-01

    Sub-surface fatigue crack growth at non metallic inclusions is studied in AISI 52100 bearing steel under typical rolling contact loads. A first 2D plane strain finite element analysis is carried out to compute the stress history in the innner race at a characteristic depth, where the Dang Van...... damage factor is highest. Subsequently the stress history is imposed as boundary conditions in a periodic unit cell model, where an alumina inclusion is embedded in a AISI 52100 matrix. Cracks are assumed to grow radially from the inclusion under cyclic loading. The growth is predicted by means...

  18. 78 FR 58996 - Tapered Roller Bearings from the People's Republic of China: Notice of Court Decision Not in...

    Science.gov (United States)

    2013-09-25

    ... Sawblades Mfrs. Coalition v. United States, 626 F.3d 1374 (Fed. Cir. 2010) (``Diamond Sawblades''), the... a complaint with the CIT to challenge various aspects of the Final Results. \\2\\ Tapered Roller...

  19. Determination of the contact stresses in double-row tapered roller bearings using the finite element method, experimental analysis and analytical models

    Energy Technology Data Exchange (ETDEWEB)

    Lostado, Ruben [University of La Rioja, Logroño (Spain); Martinez, Roberto Fernandez [University of Basque Country UPV/EHU, Bilbao (Spain); MacDonald, Bryan J. [Dublin City University, Dublin (Ireland)

    2015-11-15

    Double-row Tapered roller bearings (TRBs) are mechanical devices that are designed to support high axial, radial and torque loads. This combination of loads produces high contact stresses on the bearing raceways that are difficult to predict and validate experimentally, and can cause defects like pitting and fatigue spalling. In response, theoretical models have been proposed by many researchers to calculate the approximate distribution of contact stresses over the bearing raceways. More recently, numerical methods that are based on the Finite element method (FEM) have been used to obtain the contact stresses, although this method requires that the mesh size first be adjusted. This paper shows a process for adjusting a double-row TRB Finite element (FE) model. It is based on generating successive nonlinear FE submodels to calculate the distribution of contact stresses. A theoretical model and contact pressure sensors were used to adjust and validate the Finite element (FE) model.

  20. Transient Vibration Prediction for Rotors on Ball Bearings Using Load-dependent Non-linear Bearing Stiffness

    Science.gov (United States)

    Fleming, David P.; Poplawski, J. V.

    2002-01-01

    Rolling-element bearing forces vary nonlinearly with bearing deflection. Thus an accurate rotordynamic transient analysis requires bearing forces to be determined at each step of the transient solution. Analyses have been carried out to show the effect of accurate bearing transient forces (accounting for non-linear speed and load dependent bearing stiffness) as compared to conventional use of average rolling-element bearing stiffness. Bearing forces were calculated by COBRA-AHS (Computer Optimized Ball and Roller Bearing Analysis - Advanced High Speed) and supplied to the rotordynamics code ARDS (Analysis of Rotor Dynamic Systems) for accurate simulation of rotor transient behavior. COBRA-AHS is a fast-running 5 degree-of-freedom computer code able to calculate high speed rolling-element bearing load-displacement data for radial and angular contact ball bearings and also for cylindrical and tapered roller beatings. Results show that use of nonlinear bearing characteristics is essential for accurate prediction of rotordynamic behavior.

  1. Dynamical Simulations of a Flexible Rotor in Cylindrical Uncavitated and Cavitated Lubricated Journal Bearings

    Directory of Open Access Journals (Sweden)

    Alessandro Ruggiero

    2018-04-01

    Full Text Available Due to requirements of their operating conditions, such as high speed, high flexibility and high efficiency, rotating machines are designed to obtain larger operating ranges. These operating conditions can increase the risk of fluid-induced instability. In fact, the presence of non-linear fluid forces when the threshold speed is overcome by the rotational speed, can generate rotor lateral self-excited vibrations known as “oil whirl” or “oil whip”. These instabilities derive from the interaction between the rotor and the sliding bearing and they are typically sub-synchronous and they contribute to eventual rubbing between rotor and stator with consequent damage to the rotating machines. For these reasons, the aim of this paper is to numerically investigate the differences in the dynamic behaviour of a flexible rotor supported by cylindrical lubricated journal bearings. The study considers two different cases, uncavitated and cavitated lubricated films, in order to develop an original Matlab-Simulink algorithm for the numerical solution of the differential non-linear equations of motion of the unbalanced flexible rotor supported on hydrodynamic journal bearings. The bearings were modelled as uncavitated and cavitated (π-Film short bearings derived from classical Reynolds’ theory. Dynamic simulation allowed prediction of the shape and size of the orbit performed by the system and evaluation of the vibrating phenomena exerted by the rotor during the motion. The results show that cavitation completely modifies the behaviour of the system in every aspect. The analysis of the diagrams obtained showed that the proposed algorithm provides consistent results and represents a valuable instrument for dynamic analysis of rotating systems.

  2. Model Specification for Rework of Aircraft Engine, Power Transmission, and Accessory/Auxiliary Ball and Roller Bearings

    Science.gov (United States)

    Zaretsky, Erwin V.; Branzai, Emanuel V.

    2007-01-01

    This document provides a model specification for the rework and/or repair of bearings used in aircraft engines, helicopter main power train transmissions, and auxiliary bearings determined to be critical by virtue of performance, function, or availability. The rolling-element bearings to be processed under the provisions of this model specification may be used bearings removed after service, unused bearings returned from the field, or certain rejected bearings returned for reinspection and salvage. In commercial and military aircraft application, it has been a practice that rolling-element bearings removed at maintenance or overhaul be reworked and returned to service. Depending on the extent of rework and based upon theoretical analysis, representative life factors (LF) for bearings subject to rework ranged from 0.87 to 0.99 the lives of new bearings. Based on bearing endurance data, 92 percent of the bearing sets that would be subject to rework would result in L(sub 10) lives equaling and/or exceeding that predicted for new bearings. The remaining 8 percent of the bearings have the potential to achieve the analytically predicted life of new bearings when one of the rings is replaced at rework. The potential savings from bearing rework varies from 53 to 82 percent of that of new bearings depending on the cost, size, and complexity of the bearing

  3. Use of high frequency analysis of acoustic emission signals to determine rolling element bearing condition

    International Nuclear Information System (INIS)

    Cockerill, A; Holford, K M; Pullin, R; Clarke, A; Bradshaw, T; Cole, P

    2015-01-01

    Acoustic Emission (AE) sensors were used to detect signals arising from a cylindrical roller bearing with artificial defects seeded onto the outer raceway. An SKF N204ECP roller bearing was placed between two double row spherical roller bearings, type SKF 22202E, and loaded between 0.29 and 1.79kN. Speed was constant at 5780rpm. High frequency analysis allowed insight into the condition of the bearings through the determination of an increase in the structural resonances of the system as the size of an artificial defect was increased. As higher loads were applied, frequencies around 100kHz were excited, indicating the release of AE possibly attributed to friction and the plastic deformation as peaks, induced through engraving of the raceway, were flattened and worn down. Sensitivity of AE to this level in bearings indicates the potential of the technique to detect the early stages of bearing failure during life tests. (paper)

  4. Big bearings. Unsung hero; Kyodaina jikuuke. Hitome ni tsukanai hatarakimono

    Energy Technology Data Exchange (ETDEWEB)

    Nanba, S. [Koyo Seiko Co. Ltd., Osaka (Japan)

    1997-03-05

    This paper introduces examples of the use of big bearings. Bearings are divided largely into those used for radial load supporting and those used for thrust load supporting, while big bearings are often used for the latter usage. Thrust bearings include a cutter heat supporting bearing for tunnel excavator working underground, in addition to those used for swing motion of parabolic antennas and tower cranes. A bearing used in an excavator has an outer diameter of about half that of the excavator. The outer diameter of a shielding machine practically used in tunnel drilling currently has an outer diameter of 14,140 mm, and the outer diameter of the bearing is 7200 mm (bearing weighing 45 tons). Other big thrust bearings may include a swing tower swinging thrust bearing used in a continuous casting facility. Big radial bearings are used in iron and steel making facilities. This paper describes two examples of bearings used in this application. A spherical roller bearing to support converter trunion should be of an ultra big size to withstand total weight of about 1400 tons composed of a converter weight and weight of steel to be processed. A four-row cylindrical roller bearing to support the backup roll of a thick plate rolling mill is a bearing with durability against large loads to support reduction rolls whose size have become increasingly large. 2 refs., 5 figs.

  5. Partial tooth gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2010-01-01

    A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

  6. Roller Locking Brake

    Science.gov (United States)

    Vranish, John M.

    1993-01-01

    Roller locking brake is normally braking rotary mechanism allowing free rotation when electromagnet in mechanism energized. Well suited to robots and other machinery which automatic braking upon removal of electrical power required. More compact and reliable. Requires little electrical power to maintain free rotation and exhibits minimal buildup of heat.

  7. Enhanced DET-Based Fault Signature Analysis for Reliable Diagnosis of Single and Multiple-Combined Bearing Defects

    Directory of Open Access Journals (Sweden)

    In-Kyu Jeong

    2015-01-01

    Full Text Available To early identify cylindrical roller bearing failures, this paper proposes a comprehensive bearing fault diagnosis method, which consists of spectral kurtosis analysis for finding the most informative subband signal well representing abnormal symptoms about the bearing failures, fault signature calculation using this subband signal, enhanced distance evaluation technique- (EDET- based fault signature analysis that outputs the most discriminative fault features for accurate diagnosis, and identification of various single and multiple-combined cylindrical roller bearing defects using the simplified fuzzy adaptive resonance map (SFAM. The proposed comprehensive bearing fault diagnosis methodology is effective for accurate bearing fault diagnosis, yielding an average classification accuracy of 90.35%. In this paper, the proposed EDET specifically addresses shortcomings in the conventional distance evaluation technique (DET by accurately estimating the sensitivity of each fault signature for each class. To verify the efficacy of the EDET-based fault signature analysis for accurate diagnosis, a diagnostic performance comparison is carried between the proposed EDET and the conventional DET in terms of average classification accuracy. In fact, the proposed EDET achieves up to 106.85% performance improvement over the conventional DET in average classification accuracy.

  8. Roller-compacted concrete pavements.

    Science.gov (United States)

    2010-09-01

    Roller-compacted concrete (RCC) gets its name from the heavy vibratory steel drum and rubber-tired rollers used to help compact it into its final form. RCC has similar strength properties and consists of the same basic ingredients as conventional con...

  9. Bearing construction for refrigeration compresssor

    Science.gov (United States)

    Middleton, Marc G.; Nelson, Richard T.

    1988-01-01

    A hermetic refrigeration compressor has a cylinder block and a crankshaft rotatable about a vertical axis to reciprocate a piston in a cylinder on the cylinder block. A separate bearing housing is secured to the central portion of the cylinder block and extends vertically along the crankshaft, where it carries a pair of roller bearings to journal the crankshaft. The crankshaft has a radially extending flange which is journaled by a thrust-type roller bearing above the bearing housing to absorb the vertical forces on the crankshaft so that all three of the roller bearings are between the crankshaft and the bearing housing to maintain and control the close tolerances required by such bearings.

  10. Journal bearing

    Science.gov (United States)

    Menke, John R.; Boeker, Gilbert F.

    1976-05-11

    1. An improved journal bearing comprising in combination a non-rotatable cylindrical bearing member having a first bearing surface, a rotatable cylindrical bearing member having a confronting second bearing surface having a plurality of bearing elements, a source of lubricant adjacent said bearing elements for supplying lubricant thereto, each bearing element consisting of a pair of elongated relatively shallowly depressed surfaces lying in a cylindrical surface co-axial with the non-depressed surface and diverging from one another in the direction of rotation and obliquely arranged with respect to the axis of rotation of said rotatable member to cause a flow of lubricant longitudinally along said depressed surfaces from their distal ends toward their proximal ends as said bearing members are rotated relative to one another, each depressed surface subtending a radial angle of less than 360.degree., and means for rotating said rotatable bearing member to cause the lubricant to flow across and along said depressed surfaces, the flow of lubricant being impeded by the non-depressed portions of said second bearing surface to cause an increase in the lubricant pressure.

  11. INFLUENCE CONSTRUCTION OF THE ROLLER ON THE POWER OF THE DRIVE SYSTEM OF THE BELT CONVEYOR

    Directory of Open Access Journals (Sweden)

    Tadeusz OPASIAK

    2014-09-01

    Full Text Available The paper presents a study of new design of rollers. The study focused on the measurement of static and dynamic resistance of rotating rollers and the impact of new construction on the power consumption of the belt conveyor. Rollers have been modified through the use of class C4 bearing seals and labyrinth seal U4Exp 62/65 with a cover 2LU4 of runner construction. Measurements of static and dynamic resistance of rotating rollers were made on a universal rollers stand and power measurements were carried out on a belt conveyor power supply system Gwarek 1200 No. TW in mine KWK Mysłowice–Wesoła.

  12. Analysis of bearing steel exposed to rolling contact fatigue

    DEFF Research Database (Denmark)

    Hansen, K. T.; Fæster, Søren; Natarajan, Anand

    2017-01-01

    The objective of this work is to characterize fatigue damage in roller bearings under conditions of high load and slippage. A test rig constructed for rolling contact fatigue tests of rings is described, and test results are presented for rings taken from two spherical roller bearings. The prepar...

  13. Problematics of Reliability of Road Rollers

    Science.gov (United States)

    Stawowiak, Michał; Kuczaj, Mariusz

    2018-06-01

    This article refers to the reliability of road rollers used in a selected roadworks company. Information on the method of road rollers service and how the service affects the reliability of these rollers is presented. Attention was paid to the process of the implemented maintenance plan with regard to the machine's operational time. The reliability of road rollers was analyzed by determining and interpreting readiness coefficients.

  14. Impact Analysis of Roller System Stability for Four-High Mill Horizontal Vibration

    Directory of Open Access Journals (Sweden)

    Xiao-bin Fan

    2016-01-01

    Full Text Available In order to study the hot Compact Strip Production (CSP, four-high mill vibration characteristics, and vibration suppression method, the roller system structure stability was analyzed and calculated at first in the paper. And then, the mill stand gap was measured at field and its influence on roll transverse vibration was analyzed. The drum gear coupling effect on the roller system stability and the automatic balance conditions of the coupling transmission torque were studied; the influence of axial force caused by the roller cross on the system stability was analyzed. Finally, the roller transverse friction chatter vibration mechanics model was established; the simulation analysis was carried out with eliminating mill house-bearing clearance and adding floating support for coupling, respectively. And the characteristics of the roller “jump vibration” were studied. We applied copper gaskets to eliminate or reduce mill house-bearing clearance for suppressing the rolling mill vibration on the spot; the test results show that the roller transverse vibration was suppressed after eliminating clearance.

  15. ANALYSIS OF MOVEMENT RESISTANCE OF CONVEYOR BELT AND ROLLERS IN THE COAL MINE MYSŁOWICE-WESOŁA

    Directory of Open Access Journals (Sweden)

    Tadeusz OPASIAK

    2014-03-01

    Full Text Available The paper presents a study of new design of SAG rollers. The study focused on the measurement of static and dynamic resistance of rotating rollers and the impact of new construction on the power consumption of the conveyor. Rollers have been modified through the use of class C4 bearing seals and labyrinth seal U4Exp 62/65 with a cover 2LU4 of runner construction. Measurements of static and dynamic resistance of rotating rollers were made on a universal rollers test bench, and power measurements were carried out on a belt conveyor power supply system Gwarek 1200 No. TW in KWK Mysłowice-Wesoła

  16. Grease lubrication in rolling bearings

    CERN Document Server

    Lugt, Piet M

    2012-01-01

    The definitive book on the science of grease lubrication for roller and needle bearings in industrial and vehicle engineering. Grease Lubrication in Rolling Bearings provides an overview of the existing knowledge on the various aspects of grease lubrication (including lubrication systems) and the state of the art models that exist today. The book reviews the physical and chemical aspects of grease lubrication, primarily directed towards lubrication of rolling bearings. The first part of the book covers grease composition, properties and rheology, including thermal

  17. The 1982 epidemic--roller skating injuries.

    Science.gov (United States)

    Bunker, T. D.

    1983-01-01

    A series of 100 roller skating injuries is presented. Roller skating injuries have been occurring at a higher rate than the previously reported skateboarding epidemic of 1977. The severity of injury has been lower, 32% fractures and dislocations occurring whilst roller skating, compared to 60% whilst skateboarding. In particular a striking reduction is seen in ankle fractures. Fifty questionnaires detailing method of injury were analysed. Images p205-a Fig. 1 Fig. 2 PMID:6652406

  18. On Working Capacity Criteria for Screw-Roller Mechanisms

    Directory of Open Access Journals (Sweden)

    D. S. Blinov

    2015-01-01

    Full Text Available Today roller-screw mechanisms (RSM are the most prospective motion converters from rotary to linear type. RSM manufacturers have suggested their design in the way, similar to the rolling bearings, in static and dynamic load ratings. The latter means that during long operations the main criterion of the RSM working capacity is fatigue spalling. However, this approach does not permit to consider temporal changes of the most critical performance parameters of the RSM (such as the axial play, the efficiency factor, the axial stiffness, the accuracy, the starting torque force for zero lash RSMs, etc. through calculations. The abovementioned method was not perfect, because the choice of the main criterion of RSM working capacity was wrong. The article proves that wear-resistance is the main criterion of RSM working capacity. The proof is the RSM efficiency factor equal to 80-88% on the average. The power loss occurs because of overcoming a sliding friction between multiple (from 300 to 1000 interfacing turns of thread on the screw and the rollers as well as on the rollers and the nut. That is why the RSMs are the screwtype rolling mechanisms with an essential portion of sliding friction. High-accuracy measurements taken using the device called a form-tracer for threaded pieces permitted to determine the essential changes on the profiles of turns of threads on the rollers (a straight-line portion appeared on the radial profile; these changes could emerge only from wear. Besides, the length of this portion increased with the increasing RSM operation time. The JSC “Moskvich” has examined the RSMs, which have been put out of operation after completing their service life as parts of robot welding machines. There were no traces of fatigue spalling found on the threaded surfaces of the RSM parts, while the sizes of the straight-line portions on the turns of the roller threads were much bigger than they were during the measurements after the initial

  19. Load-bearing processes in agricultural wheel-soil systems

    NARCIS (Netherlands)

    Tijink, F.G.J.

    1988-01-01

    In soil dynamics we distinguish between loosening and loadbearing processes. Load-bearing processes which can occur under agricultural rollers, wheels, and tyres are dealt with In this dissertation.

    We classify rollers, wheels, and tyres and treat some general aspects of these

  20. Research In Diagnosing Bearing Defects From Vibrations

    Science.gov (United States)

    Zoladz, T.; Earhart, E.; Fiorucci, T.

    1995-01-01

    Report describes research in bearing-defect signature analysis - use of vibration-signal analysis to diagnose defects in roller and ball bearings. Experiments performed on bearings in good condition and other bearings in which various parts scratched to provide known defects correlated with vibration signals. Experiments performed on highly instrumented motor-driven rotor assembly at speeds up to 10,050 r/min, using accelerometers, velocity probes, and proximity sensors mounted at various locations on assembly to measure vibrations.

  1. Screw-released roller brake

    Science.gov (United States)

    Vranish, John M. (Inventor)

    1999-01-01

    A screw-released roller brake including an input drive assembly, an output drive assembly, a plurality of locking sprags, a mechanical tripper nut for unlocking the sprags, and a casing therefor. The sprags consist of three dimensional (3-D) sprag members having pairs of contact surface regions which engage respective pairs of contact surface regions included in angular grooves or slots formed in the casing and the output drive assembly. The sprags operate to lock the output drive assembly to the casing to prevent rotation thereof in an idle mode of operation. In a drive mode of operation, the tripper is either self actuated or motor driven and is translated linearly up and down against a spline and at the limit of its travel rotates the sprags which unlock while coupling the input drive assembly to the output drive assembly so as to impart a turning motion thereto in either a clockwise or counterclockwise direction.

  2. Development of ceramics for heavy-duty roller bearings in key sectors of future technologies. Ceramic bearings for turbomolecular pumps in semiconductor industry. Final report; Entwicklung von Hochleistungskeramiken fuer Keramikwaelzlager unter extremen Belastungen in Schluesselbereichen von Zukunftstechnologien. Keramikwaelzlager fuer Turbomolekularpumpen in der Halbleiterindustrie. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Stueber, H.G.; Adamietz, R.; Binninger, M. [and others

    1999-09-01

    The examined ceramic material shows high resistance against aggressive gases used in the semiconductor industry. In the test rigs for emergency bearings the full ceramic bearings without any lubricant didn't reach the requested life. Bearings with ZrO{sub 2}-rings reached higher life time compared to bearings with Si{sub 3}N{sub 4}-rings. The life of the emergency bearings increased when using C-ion implanted rings. By using this method the friction ratio decreased. In this case, bearings with ZrO{sub 2}-rings get nearly the life of the old standard hybrid emergency bearings. But they can't reach the life time of the latest state of development of hybrid bearings. A two row paired angular contact bearing seems to be a most promising modification. But this design shows problems while manufacturing. The so called pin-bush-bearing (a sliding friction bearing solution) shows good test results. It will be possible to optimise this bearing for different pumps. Tests with ceramic bearings in a conventional levitated pump were planned. It was not possible to start the tests because of the higher priority of the 'emergency bearing project'. (orig.) [German] Der untersuchte keramische Werkstoff weist eine hohe Bestaendigkeit gegenueber den in der Halbleiterindustrie verwendeten aggressiven Gasen auf. In den Fanglagerversuchen wurde deutlich, dass die untersuchten Vollkeramik-Waelzlager ohne Schmierstoff nicht die geforderten Standzeiten erreichen. Im Vergleich zwischen Si{sub 3}N{sub 4}-Ringen zur ZrO{sub 2}-Ringen lassen die Oxidringe eine hoehere Lebensdauer erwarten. Eine Verbesserung der Standzeiten konnte durch mit C-Ionen implantierten Ringe erzielt werden. Mit dieser Reibwertverbesserung konnten die Lager mit ZrO{sub 2}-Ringen zwar den alten Serienstandard mit Hybridlagern in etwa erreichen, andererseits sind zum jetzigen Serienstandard noch deutliche Unterschiede zu beobachten. Eine vielversprechende Modifikation des Lagers in Richtung eines

  3. Kinematics and Dynamics of Roller Chain Drives

    DEFF Research Database (Denmark)

    Fuglede, Niels

    There are two main subjects of this work: Kinematic and dynamic modeling and analysis of roller chain drives. In the kinematic analysis we contribute first with a complete treatment of the roller chain drive modeled as a four-bar mechanism. This includes a general, exact and approximate analysis...... which is useful for predicting the characteristic loading of the roller chain drive. As a completely novel contribution, a kinematic model and analysis is presented which includes both spans and sprockets in a simple chain drive system. A general procedure for determination of the total wrapping length...... is presented, which also allows for exact sprocket center positions for a chain with a given number of links. Results show that the total chain wrapping length varies periodically with the tooth frequency. These results are of practical importance to both the design, installation and operation of roller chain...

  4. Modelling of a mecanum wheel taking into account the geometry of road rollers

    Science.gov (United States)

    Hryniewicz, P.; Gwiazda, A.; Banaś, W.; Sękala, A.; Foit, K.

    2017-08-01

    the road rollers, is their bearings. Depending on the load, carried by the vehicle and the rotational speed of the drive wheel, the bearings themselves can greatly affect the diameter of the rollers and the whole Mecanum wheels. The solution of this problem is presented in the paper. It is illustrated with virtual models elaborated in advanced program of the CAE class.

  5. TOOL ASSEMBLY WITH BI-DIRECTIONAL BEARING

    Science.gov (United States)

    Longhurst, G.E.

    1961-07-11

    A two-direction motion bearing which is incorporated in a refueling nuclear fuel element trsnsfer tool assembly is described. A plurality of bi- directional bearing assembliesare fixed equi-distantly about the circumference of the transfer tool assembly to provide the tool assembly with a bearing surface- for both axial and rotational motion. Each bi-directional bearing assembly contains a plurality of circumferentially bulged rollers mounted in a unique arrangement which will provide a bearing surface for rotational movement of the tool assembly within a bore. The bi-direc tional bearing assembly itself is capable of rational motion and thus provides for longitudinal movement of the tool assembly.

  6. Experimental Research on the Impact of Thin-Wall Ratio and the Fillet Radius of Forming Roller on the Limiting Spinning Ratio of AMS 5504 Sheets

    Directory of Open Access Journals (Sweden)

    Kut S.

    2017-12-01

    Full Text Available Results of experimental investigations of metal spinning process of AMS 5504 sheets. cylindrical drawpieces with use of discs-shaped sheet with various diameter and thickness were shown in this work. Tests were performed on two roller metal spinning machine of a vertical axis Leifeld SFC 800 V500.

  7. Kinematics of Planetary Roller Screw Mechanism considering Helical Directions of Screw and Roller Threads

    Directory of Open Access Journals (Sweden)

    Shangjun Ma

    2015-01-01

    Full Text Available Based on the differential principle of thread transmission, an analytical model considering helical directions between screw and roller threads in planetary roller screw mechanism (PRSM is presented in this work. The model is critical for the design of PRSM with a smaller lead and a bigger pitch to realize a higher transmission accuracy. The kinematic principle of planetary transmission is employed to analyze the PRSM with different screw thread and roller thread directions. In order to investigate the differences with different screw thread and roller thread directions, the numerical model is developed by using the software Adams to validate the analytical solutions calculated by the presented model. The results indicate, when the helical direction of screw thread is identical with the direction of roller thread, that the lead of PRSM is unaffected regardless of whether sliding between screw and rollers occurs or not. Only when the direction of screw thread is reverse to the direction of roller thread, the design of PRSM with a smaller lead can be realized under a bigger pitch. The presented models and numerical simulation method can be used to research the transmission accuracy of PRSM.

  8. Profiled Roller Stress/Fatigue Life Analysis Methodology and Establishment of an Appropriate Stress/Life Exponent

    Science.gov (United States)

    1997-01-01

    The objective of this work was to determine the three dimensional volumetric stress field, surface pressure distribution and actual contact area between a 0.50" square roller with different crown profiles and a flat raceway surface using Finite Element Analysis. The 3-dimensional stress field data was used in conjunction with several bearing fatigue life theories to extract appropriate values for stress-life exponents. Also, results of the FEA runs were used to evaluate the laminated roller model presently used for stress and life prediction.

  9. Modeling of contact theories for the manipulation of biological micro/nanoparticles in the form of circular crowned rollers based on the atomic force microscope

    International Nuclear Information System (INIS)

    Korayem, M. H.; Khaksar, H.; Taheri, M.

    2013-01-01

    This article has dealt with the development and modeling of various contact theories for biological nanoparticles shaped as cylinders and circular crowned rollers for application in the manipulation of different biological micro/nanoparticles based on Atomic Force Microscope. First, the effective contact forces were simulated, and their impact on contact mechanics simulation was investigated. In the next step, the Hertz contact model was simulated and compared for gold and DNA nanoparticles with the three types of spherical, cylindrical, and circular crowned roller type contact geometries. Then by reducing the length of the cylindrical section in the circular crowned roller geometry, the geometry of the body was made to approach that of a sphere, and the results were compared for DNA nanoparticles. To anticipatory validate the developed theories, the results of the cylindrical and the circular crowned roller contacts were compared with the results of the existing spherical contact simulations. Following the development of these contact models for the manipulation of various biological micro/nanoparticles, the cylindrical and the circular crowned roller type contact theories were modeled based on the theories of Lundberg, Dowson, Nikpur, Heoprich, and Hertz for the manipulation of biological micro/nanoparticles. Then, for a more accurate validation, the results obtained from the simulations were compared with those obtained by the finite element method and with the experimental results available in previous articles. The previous research works on the simulation of nanomanipulation have mainly investigated the contact theories used in the manipulation of spherical micro/nanoparticles. However since in real biomanipulation situations, biological micro/nanoparticles of more complex shapes need to be displaced in biological environments, this article therefore has modeled and compared, for the first time, different contact theories for use in the biomanipulation of

  10. A FILTRATION METHOD AND APPARATUS INCLUDING A ROLLER WITH PORES

    DEFF Research Database (Denmark)

    2008-01-01

    The present invention offers a method for separating dry matter from a medium. A separation chamber is at least partly defined by a plurality of rollers (2,7) and is capable of being pressure regulated. At least one of the rollers is a pore roller (7) having a surface with pores allowing permeabi...

  11. High-throughput creation of micropatterned PDMS surfaces using microscale dual roller casting

    International Nuclear Information System (INIS)

    DiBartolomeo, Franklin J; Ge, Ning; Trinkle, Christine A

    2012-01-01

    This work introduces microscale dual roller casting (MDRC), a novel high-throughput fabrication method for creating continuous micropatterned surfaces using thermosetting polymers. MDRC utilizes a pair of rotating, heated cylindrical molds with microscale surface patterns to cure a continuous microstructured film. Using unmodified polydimethylsiloxane as the thermosetting polymer, we were able to create optically transparent, biocompatible surfaces with submicron patterning fidelity. Compared to other roll-to-roll fabrication processes, this method offers increased flexibility in the types of materials and topography that can be generated, including dual-sided patterning, embedded materials and tunable film thickness. (paper)

  12. Development of ceramic roller bush for diesel fuel injection pump; Nenryo funsha pump yo ceramics sei roller bush no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Noda, K; Kamiya, S; Fujimura, M; Tsuzuki, M [Toyota Motor Corp., Aichi (Japan); Taniguchi, K [Denso Corp., Aichi (Japan)

    1997-10-01

    Silicon nitride ceramics have been applied to roller bush for diesel fuel injection pump in order to improve the seizure resistance. It was found that ceramic roller bush made it possible to improve the seizure load by more than three times as compared to conventional metal roller bush when the kerosene was used as lubricant The ceramic roller bush proved to be durable under engine operating conditions. 6 refs., 13 figs., 1 tab.

  13. Rolling Bearing Life Prediction, Theory, and Application

    Science.gov (United States)

    Zaretsky, Erwin V.

    2016-01-01

    A tutorial is presented outlining the evolution, theory, and application of rolling-element bearing life prediction from that of A. Palmgren, 1924; W. Weibull, 1939; G. Lundberg and A. Palmgren, 1947 and 1952; E. Ioannides and T. Harris, 1985; and E. Zaretsky, 1987. Comparisons are made between these life models. The Ioannides-Harris model without a fatigue limit is identical to the Lundberg-Palmgren model. The Weibull model is similar to that of Zaretsky if the exponents are chosen to be identical. Both the load-life and Hertz stress-life relations of Weibull, Lundberg and Palmgren, and Ioannides and Harris reflect a strong dependence on the Weibull slope. The Zaretsky model decouples the dependence of the critical shear stress-life relation from the Weibull slope. This results in a nominal variation of the Hertz stress-life exponent. For 9th- and 8th-power Hertz stress-life exponents for ball and roller bearings, respectively, the Lundberg-Palmgren model best predicts life. However, for 12th- and 10th-power relations reflected by modern bearing steels, the Zaretsky model based on the Weibull equation is superior. Under the range of stresses examined, the use of a fatigue limit would suggest that (for most operating conditions under which a rolling-element bearing will operate) the bearing will not fail from classical rolling-element fatigue. Realistically, this is not the case. The use of a fatigue limit will significantly overpredict life over a range of normal operating Hertz stresses. (The use of ISO 281:2007 with a fatigue limit in these calculations would result in a bearing life approaching infinity.) Since the predicted lives of rolling-element bearings are high, the problem can become one of undersizing a bearing for a particular application. Rules had been developed to distinguish and compare predicted lives with those actually obtained. Based upon field and test results of 51 ball and roller bearing sets, 98 percent of these bearing sets had acceptable

  14. A Comparative Experimental Study on Identification of Defect Severity in Rolling Element Bearings using Acoustic Emission and Vibration Analysis

    Directory of Open Access Journals (Sweden)

    V.V. Rao

    2015-06-01

    Full Text Available This paper describes the comparison between Vibration Analysis (VA and Acoustic Emission (AE method to predict the defect severity in rolling element bearings with respect to the gradual increase of defect size. In bearing fault diagnosis vibration based methods are very popular, but the signals acquired by its transducers from the bearings are distorted by other faults and mechanical noise from the equipment. Vibration based methods are effective when the defect in the bearings has already become severe. AE is a non destructive testing (NDT technique used in structural health monitoring and its application for bearing defect diagnosis is gaining momentum as an alternate diagnostic tool because of its inherent high signal-to-noise-ratio (SNR. A bearing test rig was designed and set up to study the various defects in rolling element bearings in real environment. In earlier cases, though the researchers studied on different types of seeded defects with random sizes, they could not ascertain the correlation between their defect sizes and the vibration amplitude. The experimental investigation reported in this paper is centered on seeded defect of same type with gradual increase of its size on outer race of radially loaded cylindrical roller bearings and running the defective bearing at different speeds and loads. Data acquired through AE & vibration probes simultaneously for better diagnosis. Comparisons between AE and VA over a range of speed and load conditions at gradual increase of defect size are presented and from them it is concluded that AE method is superior to identify the severity of defect.

  15. Roller Skating; Physical Education: 9.8414.

    Science.gov (United States)

    Amacker, Kathy; Mikell, Lenora

    GRADES OR AGES: Grades 7-12. SUBJECT MATTER: Methods and procedures of roller skating. ORGANIZATION AND PHYSICAL APPEARANCE: The contents are divided into six areas, which are Course Guidelines, Course Description and Accreditation Standard Broad Goal, Course of Study Behavioral Objectives, Course Content, Learning Activities and Teaching…

  16. Roller compaction of moist pharmaceutical powders.

    Science.gov (United States)

    Wu, C-Y; Hung, W-L; Miguélez-Morán, A M; Gururajan, B; Seville, J P K

    2010-05-31

    The compression behaviour of powders during roller compaction is dominated by a number of factors, such as process conditions (roll speed, roll gap, feeding mechanisms and feeding speed) and powder properties (particle size, shape, moisture content). The moisture content affects the powder properties, such as the flowability and cohesion, but it is not clear how the moisture content will influence the powder compression behaviour during roller compaction. In this study, the effect of moisture contents on roller compaction behaviour of microcrystalline cellulose (MCC, Avicel PH102) was investigated experimentally. MCC samples of different moisture contents were prepared by mixing as-received MCC powder with different amount of water that was sprayed onto the powder bed being agitated in a rotary mixer. The flowability of these samples were evaluated in terms of the poured angle of repose and flow functions. The moist powders were then compacted using the instrumented roller compactor developed at the University of Birmingham. The flow and compression behaviour during roller compaction and the properties of produced ribbons were examined. It has been found that, as the moisture content increases, the flowability of moist MCC powders decreases and the powder becomes more cohesive. As a consequence of non-uniform flow of powder into the compaction zone induced by the friction between powder and side cheek plates, all produced ribbons have a higher density in the middle and lower densities at the edges. For the ribbons made of powders with high moisture contents, different hydration states across the ribbon width were also identified from SEM images. Moreover, it was interesting to find that these ribbons were split into two halves. This is attributed to the reduction in the mechanical strength of moist powder compacts with high moisture contents produced at high compression pressures. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  17. Self-Mobilization Using a Foam Roller Versus a Roller Massager: Which Is More Effective for Increasing Hamstrings Flexibility?

    Science.gov (United States)

    DeBruyne, Danielle M; Dewhurst, Marina M; Fischer, Katelyn M; Wojtanowski, Michael S; Durall, Chris

    2017-01-01

    Clinical Scenario: Increasing the length of the muscle-tendon unit may prevent musculotendinous injury. Various methods have been proposed to increase muscle-tendon flexibility, including self-mobilization using foam rollers or roller massagers, although the effectiveness of these devices is uncertain. This review was conducted to determine if the use of foam rollers or roller massagers to improve hamstrings flexibility is supported by moderate- to high-quality evidence. Are foam rollers or roller massagers effective for increasing hamstrings flexibility in asymptomatic physically active adults? Summary of Key Findings: The literature was searched for studies on the effects of using foam rollers or roller massagers to increase hamstrings flexibility in asymptomatic physically active adults. Four randomized controlled trials were included; 2 studies provided level 2 or 3 evidence regarding foam rollers and 2 studies provided level 2 or 3 evidence regarding roller massagers. Both roller-massager studies reported increases in hamstrings flexibility after treatment. Data from the foam-roller studies did not demonstrate a statistically significant increase in hamstrings flexibility, but 1 study did demonstrate a strong effect size. Clinical Bottom Line: The reviewed moderate-quality studies support the use of roller massagers but provide limited evidence on the effectiveness of foam rolling to increase hamstrings flexibility in asymptomatic physically active adults. Flexibility gains may be improved by a longer duration of treatment and administration by a trained therapist. Gains appear to decline rapidly postrolling. Neither device has been shown to confer a therapeutic benefit superior to static stretching, and the effectiveness of these devices for preventing injury is unknown. Strength of Recommendation: Grade B evidence supports the use of roller massagers to increase hamstrings flexibility in asymptomatic physically active adults.

  18. Space Station alpha joint bearing

    Science.gov (United States)

    Everman, Michael R.; Jones, P. Alan; Spencer, Porter A.

    1987-01-01

    Perhaps the most critical structural system aboard the Space Station is the Solar Alpha Rotary Joint which helps align the power generation system with the sun. The joint must provide structural support and controlled rotation to the outboard transverse booms as well as power and data transfer across the joint. The Solar Alpha Rotary Joint is composed of two transition sections and an integral, large diameter bearing. Alpha joint bearing design presents a particularly interesting problem because of its large size and need for high reliability, stiffness, and on orbit maintability. The discrete roller bearing developed is a novel refinement to cam follower technology. It offers thermal compensation and ease of on-orbit maintenance that are not found in conventional rolling element bearings. How the bearing design evolved is summarized. Driving requirements are reviewed, alternative concepts assessed, and the selected design is described.

  19. Development of roller type side slip tester; Roller shiki side slip tester no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Nishiyama, S [Hiroshima City Industrial Technology Institute, Hiroshima (Japan); Harada, S; Harada, K

    1997-10-01

    This paper presents a new development of roller type side slip tester (RTSSI). The test equipment consists of four parts, which are developed in this research. These are a roller part, a control part, a remote control part and a CRT part. In this study, we especially investigated the mechanism and performance between tire and roller. We analyzed the amount of side slip with various toe angles. The developed tester is examined under the conditions that is considered in industrial applications. We investigated the influences of toe angle, size of tire, pressure of tire, coefficient of friction between tire and roller, pushing force of tire, revolution velocity of roller, axle load and so on. The validity of the developed RTSST is confirmed under these conditions. It was found that the RTSST can be used in practical use. Some measurement results are presented in the form of parametric plots. And we also compared measurements data between the RTSST and that of flat type using several automobiles. 4 refs., 8 figs., 4 tabs.

  20. Ice-skating and roller disco injuries in Dublin.

    OpenAIRE

    Horner, C.; McCabe, M. J.

    1984-01-01

    A comparative study was carried out on a series of 72 ice-skating and 57 roller skating injuries over a sixteen month period. The average patient age was 20.5 years in the ice-skating group and 16.5 years in the roller skating group. Females predominated in both groups accounting for 72% of ice-skaters injured and 77% of roller skaters injured. Ice-skaters sustained more serious injuries than roller skaters as was evident from the significant difference in fracture numbers in the two groups. ...

  1. On-line surveillance of lubricants in bearings by means of surface acoustic waves.

    Science.gov (United States)

    Lindner, Gerhard; Schmitt, Martin; Schubert, Josephine; Krempel, Sandro; Faustmann, Hendrik

    2010-01-01

    The acoustic wave propagation in bearings filled with lubricants and driven by pulsed excitation of surface acoustic waves has been investigated with respect to the presence and the distribution of different lubricants. Experimental setups, which are based on the mode conversion between surface acoustic waves and compression waves at the interface between a solid substrate of the bearing and a lubricant are described. The results of preliminary measurements at linear friction bearings, rotation ball bearings and axial cylinder roller bearings are presented.

  2. Analysis of laboratory compaction methods of roller compacted concrete

    Science.gov (United States)

    Trtík, Tomáš; Chylík, Roman; Bílý, Petr; Fládr, Josef

    2017-09-01

    Roller-Compacted Concrete (RCC) is an ordinary concrete poured and compacted with machines typically used for laying of asphalt road layers. One of the problems connected with this technology is preparation of representative samples in the laboratory. The aim of this work was to analyse two methods of preparation of RCC laboratory samples with bulk density as the comparative parameter. The first method used dynamic compaction by pneumatic hammer. The second method of compaction had a static character. The specimens were loaded by precisely defined force in laboratory loading machine to create the same conditions as during static rolling (in the Czech Republic, only static rolling is commonly used). Bulk densities obtained by the two compaction methods were compared with core drills extracted from real RCC structure. The results have shown that the samples produced by pneumatic hammer tend to overestimate the bulk density of the material. For both compaction methods, immediate bearing index test was performed to verify the quality of compaction. A fundamental difference between static and dynamic compaction was identified. In static compaction, initial resistance to penetration of the mandrel was higher, after exceeding certain limit the resistance was constant. This means that the samples were well compacted just on the surface. Specimens made by pneumatic hammer actively resisted throughout the test, the whole volume was uniformly compacted.

  3. Ice-skating and roller disco injuries in Dublin.

    Science.gov (United States)

    Horner, C.; McCabe, M. J.

    1984-01-01

    A comparative study was carried out on a series of 72 ice-skating and 57 roller skating injuries over a sixteen month period. The average patient age was 20.5 years in the ice-skating group and 16.5 years in the roller skating group. Females predominated in both groups accounting for 72% of ice-skaters injured and 77% of roller skaters injured. Ice-skaters sustained more serious injuries than roller skaters as was evident from the significant difference in fracture numbers in the two groups. Ice-skating fractures accounted for 40% of all injuries while roller skating fractures were only 14% of their total injuries. The majority of ice-skating fractures occurred in females. As a result of our study we recommended several preventative measures. Images p207-a p207-b PMID:6487948

  4. Mathematical simulation of bearing ring grinding process

    Science.gov (United States)

    Koltunov, I. I.; Gorbunova, T. N.; Tumanova, M. B.

    2018-03-01

    The paper suggests the method of forming a solid finite element model of the bearing ring. Implementation of the model allowed one to evaluate the influence of the inner cylindrical surface grinding scheme on the ring shape error.

  5. Cylindrical neutron generator

    Science.gov (United States)

    Leung, Ka-Ngo [Hercules, CA

    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.

  6. 21 CFR 870.4370 - Roller-type cardiopulmonary bypass blood pump.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Roller-type cardiopulmonary bypass blood pump. 870... Roller-type cardiopulmonary bypass blood pump. (a) Identification. A roller-type cardiopulmonary bypass blood pump is a device that uses a revolving roller mechanism to pump the blood through the...

  7. Wear numbers for ball cup and journal bearings

    NARCIS (Netherlands)

    Ligterink, D.J.; Moes, H.

    1980-01-01

    A wear number is defined for ball cup bearings and for journal bearings where the cup and the cylindrical bearing are made of soft material. This dimensionless wear number provides a relation between the following five quantities: the radius of the ball or the length of the journal bearing in

  8. Passive magnetic bearing system

    Science.gov (United States)

    Post, Richard F.

    2014-09-02

    An axial stabilizer for the rotor of a magnetic bearing provides external control of stiffness through switching in external inductances. External control also allows the stabilizer to become a part of a passive/active magnetic bearing system that requires no external source of power and no position sensor. Stabilizers for displacements transverse to the axis of rotation are provided that require only a single cylindrical Halbach array in its operation, and thus are especially suited for use in high rotation speed applications, such as flywheel energy storage systems. The elimination of the need of an inner cylindrical array solves the difficult mechanical problem of supplying support against centrifugal forces for the magnets of that array. Compensation is provided for the temperature variation of the strength of the magnetic fields of the permanent magnets in the levitating magnet arrays.

  9. Wind Turbine Design Guideline DG03: Yaw and Pitch Rolling Bearing Life

    Energy Technology Data Exchange (ETDEWEB)

    Harris, T.; Rumbarger, J. H.; Butterfield, C. P.

    2009-12-01

    This report describes the design criteria, calculation methods, and applicable standards recommended for use in performance and life analyses of ball and roller (rolling) bearings for yaw and pitch motion support in wind turbine applications. The formulae presented here for rolling bearing analytical methods and bearing-life ratings are consistent with methods in current use by wind turbine designers and rolling-bearing manufacturers.

  10. ROLLER RIG TESTING AT THE CZECH TECHNICAL UNIVERSITY

    Directory of Open Access Journals (Sweden)

    J. Kalivoda

    2016-08-01

    Full Text Available Purpose. Although the advancements in computer simulation technology have paved way to provide very reliable simulation results, track tests still play an essential role during the process of development and homologation of any railway vehicle. On the other hand, track tests depend on weather conditions, are difficult to organize and are not suitable for testing vehicles in critical situations. On a roller rig, the tested vehicle is longitudinally fixed and a track is replaced by rotating rollers. Such device offer testing of railway vehicle running dynamics in safe and stable laboratory environment. The purpose of an article is to investigate and describe roller rig testing at the Czech technical university in Prague (CTU. Methodology. In the paper it is shown the history of development of the scaled CTU roller rig from the earlier stages until the current projects for which the CTU roller rig is utilized for. The current design of the experimental bogie, roller rig, sensors instrumentation and types of experiments conducted at the CTU roller rig are described in more detail. Findings. Although the differences in vehicle behaviour on a track and a scaled model on a roller rig are not negligible, scaled roller rig experiments are found as a relatively inexpensive way for verification and demonstration of computer simulations results. They are especially useful for verification of multibody system simulations (MBS of entirely new running gear concepts. Originality. The CTU roller rig is currently used for the experiments with active controlled wheelset guidance. According to simulations results published in many papers such systems offer, in principle, better performance compared to conventional passive vehicles. However, utilization and testing of active controlled wheelset guidance on vehicles is still rare. CTU roller rig serves as a tool to verify computer simulations and demonstrate benefits of active wheelset guidance. Practical value

  11. Roller-chain Drives Mechanics using Multibody Dynamics Tools

    DEFF Research Database (Denmark)

    Ambrosio, Jorge A. C.; Hansen, John Michael

    1999-01-01

    An integrated model for the simulation of roller-chain drives based on a multibody dynamics methodology is presented here in order to describeits complex dynamic behavior. The chain is modeled by masses lumped at the roller locations and connected by translational spring-damper elements in order ...... engagement on the sprockets responsible for the polygonal effect is thoroughly analyzed and the induced impulsive forces developed during that action are treated by a strategy where kinematic constraints between sprockets and rollers are added and deleted....

  12. Vibration based blind identification of bearing failures for autonomous wireless sensor nodes

    NARCIS (Netherlands)

    Sanchez Ramirez, Andrea; Loendersloot, Richard; Tinga, Tiedo; Bregon, A.; Daigle, M.J.

    2014-01-01

    Despite all the attention received by maintainers, undetected roller bearings failures are still a major source of concern in relation with reliability losses and high maintenance costs. Because of that, bearing condition assessment through vibration monitoring remains an intensive topic of

  13. Engine testing of ceramic cam-roller followers. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kalish, Y. [Detroit Diesel Corp., MI (United States)

    1992-04-01

    For several years, DDC has been developing monolithic ceramic heat engine components. One of the components, developed for an application in our state-of-the-art on-highway, heavy-duty diesel engine, the Series 60, is a silicon nitride cam-roller follower. Prior to starting this program, each valve train component in the Series 60 was considered for conversion to a ceramic material. Many advantages and disadvantages (benefits and risks) were considered. From this effort, one component was selected, the cam-roller follower. Using a system design approach, a ceramic cam-roller follower offered functional improvement at a reasonable cost. The purpose of the project was to inspect and test 100 domestically produced silicon nitride cam-roller followers built to the requirements of the DDC series 60 engine.

  14. Engine testing of ceramic cam-roller followers

    Energy Technology Data Exchange (ETDEWEB)

    Kalish, Y. (Detroit Diesel Corp., MI (United States))

    1992-04-01

    For several years, DDC has been developing monolithic ceramic heat engine components. One of the components, developed for an application in our state-of-the-art on-highway, heavy-duty diesel engine, the Series 60, is a silicon nitride cam-roller follower. Prior to starting this program, each valve train component in the Series 60 was considered for conversion to a ceramic material. Many advantages and disadvantages (benefits and risks) were considered. From this effort, one component was selected, the cam-roller follower. Using a system design approach, a ceramic cam-roller follower offered functional improvement at a reasonable cost. The purpose of the project was to inspect and test 100 domestically produced silicon nitride cam-roller followers built to the requirements of the DDC series 60 engine.

  15. A study on rheological characteristics of roller milled fenugreek fractions.

    Science.gov (United States)

    Sakhare, Suresh D; Inamdar, Aashitosh A; Prabhasankar, P

    2016-01-01

    Fenugreek seeds were fractionated by roller milling to get various fractions. The roller milled fractions and whole fenugreek flour (WFF) were evaluated for the flow behavior and time-dependent flow properties using a rotational viscometer at the temperatures of 10-60 (0)C. The samples subjected to a programmed shear rate increase linearly from 0 to 300 s(-1) in 3 min and successive decrease linearly shear rate from 300 s(-1) to 0 in 3 min. The roller milled fractions and WFF paste exhibited non-Newtonian pseudoplastic behavior. Difference in hysteresis loop area was observed among the roller milled fractions and WFF, being more noticeable at lower temperatures. Power law and Casson models were used to predict flow properties of samples. The power law model described well the flow behavior of the roller milled fractions and WFF at temperatures tested. Except flour (FL) fraction, consistency coefficient, m, increased with the temperature both in the forward and backward measurements. The roller milled fractions and WFF exhibited rheopectic behavior that increased viscosity with increasing the shear speed and the temperature. For all the sample tested, initial shear stress increased with increase in shear rate and temperature.

  16. Bearing system

    Science.gov (United States)

    Kapich, Davorin D.

    1987-01-01

    A bearing system includes backup bearings for supporting a rotating shaft upon failure of primary bearings. In the preferred embodiment, the backup bearings are rolling element bearings having their rolling elements disposed out of contact with their associated respective inner races during normal functioning of the primary bearings. Displacement detection sensors are provided for detecting displacement of the shaft upon failure of the primary bearings. Upon detection of the failure of the primary bearings, the rolling elements and inner races of the backup bearings are brought into mutual contact by axial displacement of the shaft.

  17. Fatigue life of drilling bit bearings under arbitrary random loads

    Energy Technology Data Exchange (ETDEWEB)

    Talimi, M.; Farshidi, R. [Calgary Univ., AB (Canada)

    2009-07-01

    A fatigue analysis was conducted in order to estimate the bearing life of a roller cone rock bit under arbitrary random loads. The aim of the study was to reduce bearing failures that can interrupt well operations. Fatigue was considered as the main reason for bearing failure. The expected value of cumulative fatigue damage was used to estimate bearing life. An equation was used to express the relation between bearing life and bearing load when the bearing was subjected to a steady load and constant speed. The Palmgren-Miner hypothesis was used to determine the ultimate tensile strength of the material. The rain flow counting principle was used to determine distinct amplitude cycles. Hertzian equations were used to determine maximum stress loads. Fourier series were used to obtain simple harmonic functions for estimating stress-life relations. It was concluded that the method can be used during the well planning phase to prevent bearing failures. 6 refs.

  18. 3000-HP Roller Gear Transmission Development Program. Volume 3. Roller Gear Manufacture

    Science.gov (United States)

    1975-07-01

    power is fed through the ramp roller clutch type free- wheel units to spur gears which mesh with the combining spur gear whose centerline is common...when the engine tends to turn faster than the main rotor shaft. It is in the free- wheel mode when the main rotor shaft tends to turn faster than the...gears are cut progrind at this time. Check face runout on each end of largo gears. Not to exceed .002" TIR 30 EBW one end 40 EBW opposite end

  19. Dropout Reasons in Iranian Youth Roller Skaters

    Directory of Open Access Journals (Sweden)

    Hosein H E Y D A R I

    2014-12-01

    Full Text Available The main drop - out reasons from the sport of roller skating amongst Iranian youth skaters has been examined. A questionnaire with 53 items (adopted from Enoksen, 2011 representing seven subscales namel y: training factors and facilities, executive factors and team, education and work obligations, motivational aspects, social - cultural environment, choice of other sport activities and interests and economic factors was especially developed for this researc h. Responses were measured on a Likert scale ranging from “strongly disagree” to “strongly agree” in relation to each statement. In all 11 2 skaters predominantly male (mean age 17.1, SD = 1.63 with a mean = 5.43 years of experience (SD = 2.92 that had di scontinued in the past two years completed the questionnaire. Results of one sample t - tests showed that all factors expect “social - cultural environment” are significant indicators for drop out from skating with “economical factors” scoring the highest rank ing. Correlational analysis showed that younger participants agree more strongly th at “executive factors and team” and “education and work obligations” were the best predictors of drop out. Those with fewer years of experience considered “training factors and facilities”, “motivational aspects and social and cultural environment” as more likely reasons for quitting. Implications of the findings are discussed.

  20. Development of a cylindrical gas-fired furnace for reycling ...

    African Journals Online (AJOL)

    This study presents the development of a cylindrical gas-fired furnace, which could be used for recycling aluminum in small-scale foundries in Nigeria. The crucible, combustion chamber, suspension shaft and bearings were appropriately sized. The furnace chamber was 410 mm high and 510 mm diameter and had a ...

  1. Failure Analysis and Thermochemical Surface Engineering of Bearings in the Wind Turbine Drivetrain

    DEFF Research Database (Denmark)

    West, Ole H.E.; Dahl, Kristian Vinter; Christiansen, Thomas Lundin

    charged rollers to reproduce WEC formation. The influence of different hoop stress levels was studied. The fracture surfaces as well as formed WECs were investigated. A detrimental effect of higher hoop stress levels on roller lifetime was found and based on the analysis of the formed WECs an incremental...... the influence of different alloying concepts, prior heat treatments and nitriding parameters on the case properties. With optimum nitriding conditions a maximum nitriding depth of 800 μm was achieved, without formation of a thick porous compound layer. The build-up of near surface compressive stresses...... was confirmed by synchrotron X–ray diffraction stress analysis. The performance of surface engineered rollers was evaluated by RCF testing under conditions that are known to provoke failure in rollers made from a standard bearing steel. One of the nitrided materials showed promising results....

  2. Structured cylindrical targets

    International Nuclear Information System (INIS)

    Arnold, R.

    1986-01-01

    A variety of experimental concepts using high-energy heavy-ion beams in cylindrical targets have been studied through numerical simulation. With an accelerator planned for GSl, plasma temperatures of 100 eV can be reached by cylindrical compression, using inhomogeneous hollow-shell targets. Magnetic insulation, using external fields, has been explored as an aid in reaching high core temperatures. Experiments on collision-pumped x-ray laser physics are also discussed. (ii) Two-dimensional PlC code simulations of homogeneous solid targets show hydrodynamic effects not found in previous 1-D calculations. (iii) Preliminary ideas for an experiment on non-equilibrium heavy-ion charge-states using an existing accelerator and a pre-formed plasma target are outlined. (author)

  3. Structured cylindrical targets

    International Nuclear Information System (INIS)

    Arnold, R.; Lackner-Russo, D.; Meyer-ter-Vehn, J.; Hoffmann, I.

    1986-01-01

    A variety of experimental concepts using high-energy heavy-ion beams in cylindrical targets have been studied through numerical simulation. With an accelerator planned for GSl, plasma temperatures of 100 eV can be reached by cylindrical compression, using inhomogenous hollow-shell targets. Magnetic insulation, using external fields, has been explored as an aid in reaching high core temperatures. Experiments on collision-pumped x-ray laser physics are also discussed. (ii) Two-dimensional PlC code simulations of homogeneous solid targets show hydrodynamic effects not found in previous l-D calculations. (iii) Preliminary ideas for an experiment on non-equilibrium heavy-ion charge-states using an existing accelerator and a pre-formed plasma target are outlined. (author)

  4. RELATIONSHIP BETWEEN ROLLING AND SLIP RESISTANCE IN ROLLING BEARINGS

    Directory of Open Access Journals (Sweden)

    L. M. Bondarenko

    2016-06-01

    Full Text Available Purpose. About one of the causes of slip rolling is known from the second half of the 19th century, it was believed that the slip resistance appears at the place of contact due to different speeds on the arc of contact. Only in the mid-20th century it was proved that this resistance is negligible in rolling resistance. However (for some unknown reason it is ignored the fact that in practice in rolling bearings may rotate both the inner ring with a stationary outer one, and vice versa almost in equal relations. It is not taken into account the fact that the ball or roller in the rolling bearings runs the different distance along the roller path of the outer and inner bearing cages in one revolution. This fact is not taken into account in determining the calculated values for the friction coefficient of a rolling bearing reduced to the shaft. Therefore, the aim of this work is to determine the influence of path length on the track riding the outer and inner race of the bearing on the determination of the calculated value of the coefficient of friction of rolling bearings is given to the shaft. Methodology. The solution technique is based on the theory of plane motion of a rigid body, the theory of Hertzian contact deformation and the analytical dependencies for determination of coefficient of rolling friction. Findings. The obtained dependences on determination of rolling resistance of the balls or rollers along the bearing tracks of inner and outer bearing cages as well as path difference metering of the rolling on them allows to analytically obtain the rolling resistance and slipping for any size of bearings and different devices of bearing units. It is also possible at the design stage of rolling nodes to handle not only the design but also the content of the node. Originality. Using the analytical dependences for determination of the rolling resistance of bodies at point and line contacts, and also account for the difference in the path of the

  5. Flywheel Challenge: HTS Magnetic Bearing

    International Nuclear Information System (INIS)

    Werfel, F N; Floegel-Delor, U; Riedel, T; Rothfeld, R; Wippich, D; Goebel, B

    2006-01-01

    A 200 mm cylindrical engineering prototype high temperature superconducting (HTS) was designed and fabricated. Measurements show that the 17 kg PM rotor can suspend safely 1000 kg in axial direction and 470 kg radially. The rationale for the bearing performance is to stabilize a 400 kg rotor of a new compact 5 kWh/280 kW flywheel energy storage system (COM - FESS). Measurements of the magnetic bearing force, stiffness and drag-torque are presented indicated the successful targeting a milestone in the HTS bearing technology. The influence of the PM configuration and the YBCO temperature on the bearing performance was experimentally studied, providing high-force or high-stiffness behaviour. The axial stiffness 5 kN/mm at 0.5 mm displacement is the highest value of a HTS bearing we know

  6. Analisa Beban Kerja Dan Gaya Dinamis Pada Round Roller Dan Sliding Roller Untuk Sistem CVT (Continuously Variable Transmission Sepeda Motor Matic

    Directory of Open Access Journals (Sweden)

    Ahmad Bagus Prasojo

    2017-01-01

    Full Text Available Primary shave weight atau sering disebut roller merupakan salah satu komponen dari sistem CVT pada motor matik yang sering mengalami kerusakan, baik itu aus maupun crack atau pecah. Metodologi yang dilakukan pada penelitian ini adalah menganalisa beban kerja (gaya yang dialami oleh roller. Selanjutnya akan dihitung besar tegangan (stress yang terjadi pada roller menggunakan teori tegangan kontak (contact stress. Kemudian analisa akan dilanjutkan menggunakan teori kelelahan (fatigue. Gaya normal yang didapat pada posisi stasioner sebesar 37,268 N dan posisi puncak sebesar 525,279 N. Untuk total tegangan ekivalen yang terjadi berbeda dikarenakan luasan kontaknya, round roller dengan luasan kontak yang lebih kecil menghasilkan total tegangan yang lebih besar yaitu 21,423 MPa sedangkan sliding roller sebesar 14,559 MPa. Dengan frekuensi real pembebanan roller sebesar 0,0667 Hz dan berdasarkan teori kelelahan Gerber stress amplitude round roller didapatkan 8,8756 Mpa dan untuk sliding roller sebesar 6,195 Mpa. Jadi setelah stress amplitude diplotkan pada sn-curve PTFE hasil prediksi umur untuk round roller adalah 4,081 ≈ 4 bulan dan untuk sliding roller adalah 5,89 ≈ 6 bulan.

  7. Pediatric fractures during skateboarding, roller skating, and scooter riding.

    Science.gov (United States)

    Zalavras, Charalampos; Nikolopoulou, Georgia; Essin, Daniel; Manjra, Nahid; Zionts, Lewis E

    2005-04-01

    Skateboarding, roller skating, and scooter riding are popular recreational and sporting activities for children and adolescents but can be associated with skeletal injury. The purpose of this study is to describe the frequency and characteristics of fractures resulting from these activities. Fractures from skateboarding, roller skating, and scooter riding compose a considerable proportion of pediatric musculoskeletal injuries. Case series; Level of evidence, 4. Demographic data and injury characteristics were analyzed for all patients who presented to the pediatric fracture clinic of the level I trauma center from January 2001 to May 2002 after sustaining fractures due to skateboarding, roller skating, and scooter riding. Among a total of 2371 fractures, the authors identified 325 fractures (13.7%) that occurred during one of these activities. There were 187 patients (mean age, 13 years; 95% male) who sustained 191 skateboard-related fractures, 64 patients (mean age, 10.8 years; 54% male) who sustained 65 fractures while roller skating, and 66 patients (mean age, 9.7 years; 64% male) who sustained 69 fractures while riding a scooter. The forearm was fractured most often, composing 48.2% of skate-boarding fractures, 63.1% of roller-skating fractures, and 50.7% of fractures due to scooter riding. Of the forearm fractures, 94% were located in the distal third. In the skateboarding group, 10 of 191 (5.2%) fractures were open injuries of the forearm, compared to 6 of 2046 (0.3%) fractures caused by other mechanisms of injury (significant odds ratio, 18.8). Skateboarding, roller-skating, and scooter-riding accidents result in a large proportion of pediatric fractures. An open fracture, especially of the forearm, was more likely to be caused by skateboarding than by other mechanisms of injury. Use of wrist and forearm protective equipment should be considered in all children who ride a skateboard.

  8. Direct fabrication of rigid microstructures on a metallic roller using a dry film resist

    International Nuclear Information System (INIS)

    Jiang, Liang-Ting; Huang, Tzu-Chien; Chang, Chih-Yuan; Ciou, Jian-Ren; Yang, Sen-Yeu; Huang, Po-Hsun

    2008-01-01

    This paper presents a novel method to fabricate a metallic roller mold with microstructures on its surface using a dry film resist (DFR). The DFR is laminated uniformly onto the curvy surface of a copper roller. After that, the micro-scale photoresist on the surface of the roller can be patterned by non-planar lithography using a flexible film photomask, followed by ferric chloride wet etching to obtain the desired microstructures. This method overcomes the uniformity issue of photoresist coating on rollers, and solves the molds sliding problem during the embossing process because the microstructures are fabricated directly on the roller surface. Furthermore, the rigid metallic roller mold has excellent strength durability and temperature endurance, which can be used in roller hot embossing with a high embossing pressure. The fabricated microstructure roller mold is used as a mold in the hybrid extrusion roller embossing process and successfully fabricates uniform micro-scale prominent line arrays on PC films. This result proves that the roller fabricated by this method can be successfully used in roller embossing for microstructure mass production. The excellent flatness of dry film resist laminating is the key in this fabrication process. The flexible film photomask can be easily designed using CAD software; this roller fabrication method enhances the design flexibility and reduces the cost and time

  9. Dropping a particle out of a roller coaster

    International Nuclear Information System (INIS)

    Mungan, Carl E; Lipscombe, Trevor C

    2014-01-01

    A rider in a roller coaster lets go of a particle such as a small marble. How far does the marble travel horizontally from the point of release before hitting the ground, assuming the speed of the roller coaster is determined by conservation of mechanical energy starting from the highest hill up which it was pulled? Where should the marble be released along the track if one wishes to maximize the range of the marble? These questions constitute interesting variations on conventional problems in two-dimensional kinematics, appropriate for an undergraduate course in classical mechanics. Exploration of various shapes of tracks could form interesting student projects for numerical or experimental investigation. (paper)

  10. Tribology of a Combined Yaw Bearing and Brake for Wind Turbines

    DEFF Research Database (Denmark)

    Poulios, Konstantinos

    disc brake is typically included as an independent system. However, the increasing size of wind turbines makes roller element bearings an economically costly option. Moreover, the additional brake system increases complexity and consequently adds further production and maintenance costs. One...... of the innovations aiming at reducing complexity in the yaw system consists in combining a segmented sliding bearing and a brake into a single system. This thesis studies the tribological implications of such a hybrid sliding bearing and brake for the yaw system of wind turbines. Based to a large extent...... that are affected by the tendency for building larger units, is the yaw system of horizontal axis wind turbines. State of the art wind turbine yaw systems consist of either a large roller element bearing or a corresponding segmented sliding bearing that connects the wind turbine nacelle and tower. An additional...

  11. Development of an aerostatic bearing system for roll-to-roll printed electronics

    Science.gov (United States)

    Chen, Shasha; Chen, Weihai; Liu, Jingmeng; Chen, Wenjie; Jin, Yan

    2018-06-01

    Roll-to-roll printed electronics is proved to be an effective way to fabricate electrical devices on various substrates. High precision overlay alignment plays a key role to create multi-layer electrical devices. Multiple rollers are adopted to support and transport the substrate web. In order to eliminate the negative effect of the machining error and assembling error of the roller, a whole roll-to-roll system including two aerostatic bearing devices with arrayed restrictors is proposed in this paper. Different to the conventional roller, the aerostatic bearing device can create a layer of air film between the web and the device to realize non-contact support and transport. Based on simplified Navier–Stokes equations, the theoretical model of the air film is established. Moreover, the pressure distribution of the whole flow field and single restrictor in different positions are modeled by conducting numerical simulation with computational fluid dynamics (CFD) software FLUENT. The load capacity curves and stiffness curves are generated to provide guidance for optimizing the structure of the device. A prototype of the aerostatic bearing system is set up and the experiment tests are carried out. For the proposed aerostatic bearing roller with a diameter of 100 mm and length of 200 mm, the experimental results show the aerostatic bearing method can achieve the position accuracy in a range of 1 μm in the vertical direction of the web, which is much better than that using existing methods.

  12. Numerically Analysed Thermal Condition of Hearth Rollers with the Water-Cooled Shaft

    Directory of Open Access Journals (Sweden)

    A. V. Ivanov

    2016-01-01

    Full Text Available Continuous furnaces with roller hearth have wide application in the steel industry. Typically, furnaces with roller hearth belong to the class of medium-temperature heat treatment furnaces, but can be used to heat the billets for rolling. In this case, the furnaces belong to the class of high temperature heating furnaces, and their efficiency depends significantly on the reliability of the roller hearth furnace. In the high temperature heating furnaces are used three types of watercooled shaft rollers, namely rollers without insulation, rollers with insulating screens placed between the barrel and the shaft, and rollers with bulk insulation. The definition of the operating conditions of rollers with water-cooled shaft greatly facilitates the choice of their design parameters when designing. In this regard, at the design stage of the furnace with roller hearth, it is important to have information about the temperature distribution in the body of the rollers at various operating conditions. The article presents the research results of the temperature field of the hearth rollers of metallurgical heating furnaces. Modeling of stationary heat exchange between the oven atmosphere and a surface of rollers, and between the cooling water and shaft was executed by finite elements method. Temperature fields in the water-cooled shaft rollers of various designs are explored. The water-cooled shaft rollers without isolation, rollers with screen and rollers with bulk insulation, placed between the barrel and the water-cooled shaft were investigated. Determined the change of the thermo-physic parameters of the coolant, the temperature change of water when flowing in a pipe and shaft, as well as the desired pressure to supply water with a specified flow rate. Heat transfer coefficients between the cooling water and the shaft were determined directly during the solution based on the specified boundary conditions. Found that the greatest heat losses occur in the

  13. Physical and mechanical behaviour of a roller compacted concrete ...

    African Journals Online (AJOL)

    In order to study the behaviour of a roller compacted concrete (RCC) reinforced with polypropylene fiber, six types of RCC were made with different content of fibers (0, 0.5, 1, 1.5, 2 and 2.5 Kg/m3). The physical parameters are the density, the workability, the shrinkage and the water absorption. For the mechanical ...

  14. Influence of quartz particles on wear in vertical roller mills

    DEFF Research Database (Denmark)

    Jensen, Lucas R.D.; Friis, Henrik; Fundal, Erling

    2010-01-01

    The standard closed circuit comminution process commonly employed in industrial vertical roller mills has been analyzed to determine the influence of typical abrasive minerals on wear rates. With the main focus on raw mixes used in cement plants, synthetic mixtures imitating were prepared. Using...

  15. R+D works for the further development of high temperature reactors. (1) Captive bearing experiments for active magnetic bearings. (2) Captive bearing test for HTR blowers

    International Nuclear Information System (INIS)

    1991-01-01

    When using active magnetic bearings as blower shaft bearings, blower motors and bearings must be protected against mechanical damage in case of faults (example: total electrical supply failure due to the supply cables breaking). So-called captive bearings are provided, in order to be able to shut the blowers down safely in such faults. These captive bearings are roller bearings which are additionally fitted in the area of the blower shaft bearings, to prevent mechanical contact between the blower rotor and stator. As there was little experience available for the given boundary conditions, such as - speed, - acceleration, - bearing load, - bearing dimensions, - ambient conditions, appropriate development and tests had to be carried out. It was important to determine suitable captive bearings and the necessary ambient conditions, which will make it possible to support the failures of the magnetic bearings to be expected in 40 years' operation of the reactor without damage and to meet the requirements of the captive bearings. (orig./GL) [de

  16. Rock 'n roller coaster : an explorative study on the evolution of the European steel roller coaster industry

    NARCIS (Netherlands)

    Timmermans, B.; Bekkers, R.N.A.; Bordoli, L.

    2012-01-01

    This article investigates the 50 years evolution of the European steel roller coaster industry, which can be classified as a complex products systems (CoPS) industry. This industry is characterized as a non-shake out industry where entry can be divided in three waves, i.e. early diversifiers, new

  17. Mechanical design problems associated with turbopump fluid film bearings

    Science.gov (United States)

    Evces, Charles R.

    1990-01-01

    Most high speed cryogenic turbopumps for liquid propulsion rocket engines currently use ball or roller contact bearings for rotor support. The operating speeds, loads, clearances, and environments of these pumps combine to make bearing wear a limiting factor on turbopump life. An example is the high pressure oxygen turbopump (HPOTP) used in the Space Shuttle Main Engine (SSME). Although the HPOTP design life is 27,000 seconds at 30,000 rpms, or approximately 50 missions, bearings must currently be replaced after 2 missions. One solution to the bearing wear problem in the HPOTP, as well as in future turbopump designs, is the utilization of fluid film bearings in lieu of continuous contact bearings. Hydrostatic, hydrodynamic, and damping seal bearings are all replacement candidates for contact bearings in rocket engine high speed turbomachinery. These three types of fluid film bearings have different operating characteristics, but they share a common set of mechanical design opportunities and difficulties. Results of research to define some of the mechanical design issues are given. Problems considered include transient strat/stop rub, non-operational rotor support, bearing wear inspection and measurement, and bearing fluid supply route. Emphasis is given to the HPOTP preburner pump (PBP) bearing, but the results are pertinent to high-speed cryogenic turbomachinery in general.

  18. Shearfree cylindrical gravitational collapse

    International Nuclear Information System (INIS)

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

    2009-01-01

    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.

  19. GAS BEARING

    Science.gov (United States)

    Skarstrom, C.W.

    1960-09-01

    A gas lubricated bearing for a rotating shaft is described. The assembly comprises a stationary collar having an annular member resiliently supported thereon. The collar and annular member are provided with cooperating gas passages arranged for admission of pressurized gas which supports and lubricates a bearing block fixed to the rotatable shaft. The resilient means for the annular member support the latter against movement away from the bearing block when the assembly is in operation.

  20. Visualization in mechanics: the dynamics of an unbalanced roller

    Science.gov (United States)

    Cumber, Peter S.

    2017-04-01

    It is well known that mechanical engineering students often find mechanics a difficult area to grasp. This article describes a system of equations describing the motion of a balanced and an unbalanced roller constrained by a pivot arm. A wide range of dynamics can be simulated with the model. The equations of motion are embedded in a graphical user interface for its numerical solution in MATLAB. This allows a student's focus to be on the influence of different parameters on the system dynamics. The simulation tool can be used as a dynamics demonstrator in a lecture or as an educational tool driven by the imagination of the student. By way of demonstration the simulation tool has been applied to a range of roller-pivot arm configurations. In addition, approximations to the equations of motion are explored and a second-order model is shown to be accurate for a limited range of parameters.

  1. Simulation and Analysis of Roller Chain Drive Systems

    DEFF Research Database (Denmark)

    Pedersen, Sine Leergaard

    The subject of this thesis is simulation and analysis of large roller chain drive systems, such as e.g. used in marine diesel engines. The aim of developing a chain drive simulation program is to analyse dynamic phenomena of chain drive systems and investigate different design changes to the syst......The subject of this thesis is simulation and analysis of large roller chain drive systems, such as e.g. used in marine diesel engines. The aim of developing a chain drive simulation program is to analyse dynamic phenomena of chain drive systems and investigate different design changes...... mathematical models, and compare to the prior done research. Even though the model is developed at first for the use of analysing chain drive systems in marine engines, the methods can with small changes be used in general, as for e.g. chain drives in industrial machines, car engines and motorbikes. A novel...

  2. Grizzly bear

    Science.gov (United States)

    Schwartz, C.C.; Miller, S.D.; Haroldson, M.A.; Feldhamer, G.; Thompson, B.; Chapman, J.

    2003-01-01

    The grizzly bear inspires fear, awe, and respect in humans to a degree unmatched by any other North American wild mammal. Like other bear species, it can inflict serious injury and death on humans and sometimes does. Unlike the polar bear (Ursus maritimus) of the sparsely inhabited northern arctic, however, grizzly bears still live in areas visited by crowds of people, where presence of the grizzly remains physically real and emotionally dominant. A hike in the wilderness that includes grizzly bears is different from a stroll in a forest from which grizzly bears have been purged; nighttime conversations around the campfire and dreams in the tent reflect the presence of the great bear. Contributing to the aura of the grizzly bear is the mixture of myth and reality about its ferocity. unpredictable disposition, large size, strength, huge canines, long claws, keen senses, swiftness, and playfulness. They share characteristics with humans such as generalist life history strategies. extended periods of maternal care, and omnivorous diets. These factors capture the human imagination in ways distinct from other North American mammals. Precontact Native American legends reflected the same fascination with the grizzly bear as modern stories and legends (Rockwell 1991).

  3. Roller kiln with very low fluoride emission. The Ecokiln

    Energy Technology Data Exchange (ETDEWEB)

    Reymer, P.S.; Denissen, A.M. [TNO TPD Materials Research and Technology, Eindhoven (Netherlands)

    2001-09-01

    In most European countries the limit for fluoride emission in ceramic kiln flue gases is set at 5 mg HF/m{sup 3} flue gas. In cooperation with Royal Mosa, Royal Sphinx, Gasunie in the Netherlands and Sacmi, Italy, a roller kiln has been developed which can operate below the fore-mentioned limit. Also, a flue gas cleaning device is not necessary. 4 refs.

  4. Pin and roller attachment system for ceramic blades

    Science.gov (United States)

    Shaffer, J.E.

    1995-07-25

    In a turbine, a plurality of blades are attached to a turbine wheel by way of a plurality of joints which form a rolling contact between the blades and the turbine wheel. Each joint includes a pin and a pair of rollers to provide rolling contact between the pin and an adjacent pair of blades. Because of this rolling contact, high stress scuffing between the blades and the turbine wheel reduced, thereby inhibiting catastrophic failure of the blade joints. 3 figs.

  5. Kinematics of roller chain drives - Exact and approximate analysis

    DEFF Research Database (Denmark)

    Fuglede, Niels; Thomsen, Jon Juel

    2016-01-01

    An exact and approximate kinematic analysis of a roller chain drive modeled as a four-bar mechanism is presented. The span connects the sprockets such that they rotate in the same direction, and the sprocket size, number of teeth, and shaft center distance can be arbitrary. The driven sprocket...... to be very good agreement. All together this gives new insights into the characteristics of chain drive kinematics and the influence of main design parameters....

  6. Kinematics and Path Following Control of an Articulated Drum Roller

    Science.gov (United States)

    BIAN, Yongming; YANG, Meng; FANG, Xiaojun; WANG, Xiahui

    2017-07-01

    Automatic navigation of an articulated drum roller, which is an articulated steering type vehicle widely used in the construction industry, is highly expected for operation cost reduction and improvement of work efficiency. In order to achieve the path following control, considering that its steering system is articulated steering and two frames are articulated by an active revolute joint, a kinematic model and an error dynamic state-space equation of an articulated drum roller are proposed. Besides, a state-feedback control law based on Lyapunov stability theory is also designed, which can be proved to achieve the purpose of control by the analysis of stability. What's more, to evaluate the performance of the proposed method, simulation under the MATLAB/Simulink and experiments using positioning algorithm and errors correction at the uneven construction site are performed, with initial displacement error (-1.5 m), heading error (-0.11 rad) and steering angle (-0.19 rad). Finally, simulation and experimental results show that the errors and steering angle can decrease gradually, and converge to zero with time. Meanwhile, the control input is not saturated. An articulated drum roller can lock into a desired path with the proposed method in uneven fields.

  7. Biomechanical pole and leg characteristics during uphill diagonal roller skiing.

    Science.gov (United States)

    Lindinger, Stefan Josef; Göpfert, Caroline; Stöggl, Thomas; Müller, Erich; Holmberg, Hans-Christer

    2009-11-01

    Diagonal skiing as a major classical technique has hardly been investigated over the last two decades, although technique and racing velocities have developed substantially. The aims of the present study were to 1) analyse pole and leg kinetics and kinematics during submaximal uphill diagonal roller skiing and 2) identify biomechanical factors related to performance. Twelve elite skiers performed a time to exhaustion (performance) test on a treadmill. Joint kinematics and pole/plantar forces were recorded separately during diagonal roller skiing (9 degrees; 11 km/h). Performance was correlated to cycle length (r = 0.77; P Push-off demonstrated performance correlations for impulse of leg force (r = 0.84), relative duration (r= -0.76) and knee flexion (r = 0.73) and extension ROM (r = 0.74). Relative time to peak pole force was associated with performance (r = 0.73). In summary, diagonal roller skiing performance was linked to 1) longer cycle length, 2) greater impulse of force during a shorter push-off with larger flexion/extension ROMs in leg joints, 3) longer leg swing, and 4) later peak pole force, demonstrating the major key characteristics to be emphasised in training.

  8. Errors of car wheels rotation rate measurement using roller follower on test benches

    Science.gov (United States)

    Potapov, A. S.; Svirbutovich, O. A.; Krivtsov, S. N.

    2018-03-01

    The article deals with rotation rate measurement errors, which depend on the motor vehicle rate, on the roller, test benches. Monitoring of the vehicle performance under operating conditions is performed on roller test benches. Roller test benches are not flawless. They have some drawbacks affecting the accuracy of vehicle performance monitoring. Increase in basic velocity of the vehicle requires increase in accuracy of wheel rotation rate monitoring. It determines the degree of accuracy of mode identification for a wheel of the tested vehicle. To ensure measurement accuracy for rotation velocity of rollers is not an issue. The problem arises when measuring rotation velocity of a car wheel. The higher the rotation velocity of the wheel is, the lower the accuracy of measurement is. At present, wheel rotation frequency monitoring on roller test benches is carried out by following-up systems. Their sensors are rollers following wheel rotation. The rollers of the system are not kinematically linked to supporting rollers of the test bench. The roller follower is forced against the wheels of the tested vehicle by means of a spring-lever mechanism. Experience of the test bench equipment operation has shown that measurement accuracy is satisfactory at small rates of vehicles diagnosed on roller test benches. With a rising diagnostics rate, rotation velocity measurement errors occur in both braking and pulling modes because a roller spins about a tire tread. The paper shows oscillograms of changes in wheel rotation velocity and rotation velocity measurement system’s signals when testing a vehicle on roller test benches at specified rates.

  9. Adaptive Spindle Balancing Using Magnetically Levitated Bearings

    International Nuclear Information System (INIS)

    BARNEY, PATRICK S.; LAUFFER, JAMES P.; PETTEYS, REBECCA; REDMOND, JAMES M.; SULLIVAN, WILLIAM N.

    1999-01-01

    A technological break through for supporting rotating shafts is the active magnetic bearing (AMB). Active magnetic bearings offer some important advantages over conventional ball, roller or journal bearings such as reduced frictional drag, no physical contact in the bearing, no need for lubricants, compatibility with high vacuum and ultra-clean environments, and ability to control shaft position within the bearing. The disadvantages of the AMB system are the increased cost and complexity, reduced bearing stiffness and the need for a controller. Still, there are certain applications, such as high speed machining, biomedical devices, and gyroscopes, where the additional cost of an AMB system can be justified. The inherent actuator capabilities of the AMB offer the potential for active balancing of spindles and micro-shaping capabilities for machine tools, The work presented in this paper concentrates on an AMB test program that utilizes the actuator capability to dynamically balance a spindle. In this study, an unbalanced AMB spindle system was enhanced with an LMS (Least Mean Squares) algorithm combined with an existing PID (proportional, integral, differential) control. This enhanced controller significantly improved the concentricity of an intentionally unbalanced shaft. The study included dynamic system analysis, test validation, control design and simulation, as well as experimental implementation using a digital LMS controller

  10. Optimization of Cylindrical Hall Thrusters

    International Nuclear Information System (INIS)

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

    2007-01-01

    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.

  11. Optimization of Cylindrical Hall Thrusters

    International Nuclear Information System (INIS)

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

    2007-01-01

    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

  12. Oriented Onion Sowing by a Forked-Roller Sowing Unit

    Directory of Open Access Journals (Sweden)

    Aleksandr G.

    2018-03-01

    Full Text Available Introduction: The existing sowing machines do not provide a single feeding of the bulbs with a planting (sowing unit that leads to a violation of the agrotechnical requirements of planting bulbs. It is necessary to search new solutions to preserve the position of the bulbs in the furrow with the bottom down and their regularly spaced distribution. Materials and Methods: The article presents the design for a prototype for a planting machine equipped with a forked-roller sowing unit for orienting the onion-sowing into a furrow. Testing the forked-roller sowing unit were carried out on a flat area where the physical and mechanical properties of the soil were determined on the days of sowing, and the indices of the quality of the onion-sowing were determined. The study of the effect of the sowing machine speed on the quality of the onion-seed bulb landing was determined by the change in the translational speed of the sowing unit in the range of 0.8 m/s to 1.2 m/s with a variation interval of 0.1 m/s. The indicators of the quality of the planting of the bulbs were determined by the opening of the closed furrow. The results of laboratory-field studies of the planting machine prototype are presented. Results: The results of laboratory-field studies of a planting machine equipped with a forked-roller sowing unit for planting onion bulbs are presented. The optimal technological parameters are determined experimentally. It was determined the number of bulbs that are for up is 51 % and the regularity of planting by the forked-roller sowing unit – 79 %. These figures are provided at the forward speed of the planting machine VM = 0.9–1.0 m/s, the height of the fall of the bulb HA = 0.12 m, and the rotation frequency of the landing drum nБ = 0.47 c-1. Discussion and Conclusions: The use of a forked-roller sowing unit makes it possible to increase the proportion of onions planted by bottom down by 200 %, and the uniformity of planting bulbs by 19 %, in

  13. Roller compaction: Effect of relative humidity of lactose powder.

    Science.gov (United States)

    Omar, Chalak S; Dhenge, Ranjit M; Palzer, Stefan; Hounslow, Michael J; Salman, Agba D

    2016-09-01

    The effect of storage at different relative humidity conditions, for various types of lactose, on roller compaction behaviour was investigated. Three types of lactose were used in this study: anhydrous lactose (SuperTab21AN), spray dried lactose (SuperTab11SD) and α-lactose monohydrate 200M. These powders differ in their amorphous contents, due to different manufacturing processes. The powders were stored in a climatic chamber at different relative humidity values ranging from 10% to 80% RH. It was found that the roller compaction behaviour and ribbon properties were different for powders conditioned to different relative humidities. The amount of fines produced, which is undesirable in roller compaction, was found to be different at different relative humidity. The minimum amount of fines produced was found to be for powders conditioned at 20-40% RH. The maximum amount of fines was produced for powders conditioned at 80% RH. This was attributed to the decrease in powder flowability, as indicated by the flow function coefficient ffc and the angle of repose. Particle Image Velocimetry (PIV) was also applied to determine the velocity of primary particles during ribbon production, and it was found that the velocity of the powder during the roller compaction decreased with powders stored at high RH. This resulted in less powder being present in the compaction zone at the edges of the rollers, which resulted in ribbons with a smaller overall width. The relative humidity for the storage of powders has shown to have minimal effect on the ribbon tensile strength at low RH conditions (10-20%). The lowest tensile strength of ribbons produced from lactose 200M and SD was for powders conditioned at 80% RH, whereas, ribbons produced from lactose 21AN at the same condition of 80% RH showed the highest tensile strength. The storage RH range 20-40% was found to be an optimum condition for roll compacting three lactose powders, as it resulted in a minimum amount of fines in the

  14. Salmonella transfer during pilot plant scale washing and roller conveying of tomatoes.

    Science.gov (United States)

    Wang, Haiqiang; Ryser, Elliot T

    2014-03-01

    Salmonella transfer during washing and roller conveying of inoculated tomatoes was quantified using a pilot scale tomato packing line equipped with plastic, foam, or brush rollers. Red round tomatoes (2.3 kg) were dip inoculated with Salmonella enterica serovar Typhimurium LT2 (avirulent) (4 log CFU/g), air dried for 2 h, and then washed in sanitizer-free water for 2 min. Inoculated tomatoes were then passed single file over a 1.5-m conveyor equipped with plastic, foam, or brush rollers followed by 25 previously washed uninoculated tomatoes. Tomato samples were collected after 2 min of both washing and roller conveying, with all 25 uninoculated tomatoes collected individually after conveying. Roller surface samples were collected before and after conveying the uninoculated tomatoes. Both tomato and surface samples were quantitatively examined for Salmonella by direct plating or membrane filtration using xylose lysine Tergitol 4 agar. Regardless of the roller type, Salmonella populations on inoculated tomatoes did not significantly (P conveyors. After conveying uninoculated tomatoes over contaminated foam rollers, 96% of the 25 tomatoes were cross-contaminated with Salmonella at >100 CFU per tomato. With plastic rollers, 24 and 76% of tomatoes were cross-contaminated with Salmonella at 10 to 100 and 1 to 10 CFU per tomato, respectively. In contrast, only 8% of 25 tomatoes were cross-contaminated with brush rollers with Salmonella populations of 1 to 10 CFU per tomato. Overall, cross-contamination was greatest with foam, followed by plastic and brush rollers (P < 0.05). Adding peroxyacetic acid or chlorine to the wash water significantly decreased cross-contamination during tomato conveying, with chlorine less effective in controlling Salmonella on foam compared with plastic and brush rollers.

  15. Condition Monitoring for Roller Bearings of Wind Turbines Based on Health Evaluation under Variable Operating States

    Directory of Open Access Journals (Sweden)

    Lei Fu

    2017-10-01

    Full Text Available Condition monitoring (CM is used to assess the health status of wind turbines (WT by detecting turbine failure and predicting maintenance needs. However, fluctuating operating conditions cause variations in monitored features, therefore increasing the difficulty of CM, for example, the frequency-domain analysis may lead to an inaccurate or even incorrect prediction when evaluating the health of the WT components. In light of this challenge, this paper proposed a method for the health evaluation of WT components based on vibration signals. The proposed approach aimed to reduce the evaluation error caused by the impact of the variable operating condition. First, the vibration signal was decomposed into a set of sub-signals using variational mode decomposition (VMD. Next, the sub-signal energy and the probability distribution were obtained and normalized. Finally, the concept of entropy was introduced to evaluate the health condition of a monitored object to provide an effective guide for maintenance. In particular, the health evaluation for CM was based on a performance review over a range of operating conditions, rather than at a certain single operating condition. Experimental investigations were performed which verified the efficiency of the evaluation method, as well as a comparison with the previous method.

  16. Diagnosis of bearing creep in wind turbine gearboxes

    DEFF Research Database (Denmark)

    Skrimpas, Georgios Alexandros; Liu, Zhenyan; Hilmisson, Reynir

    2016-01-01

    One of the most wide spread gearbox topologies in the wind energy sector consists of a slow rotating planetary stage, an intermediate speed parallel stage and finally a high speed parallel stage driving the generator rotor. The shafts of the two latter stages are supported by ball or roller...... bearings where their outer races are fixed to the gearbox and their inner races rotate at the corresponding shaft speed. Bearing inner race defects are frequently encountered in gearboxes leading to either replacement of the whole unit or exchange of the shaft or bearing where feasible. The present work...... deals with the evaluation of the development of an inner race defect from surface pitting to race axial crack resulting in excessive rotational looseness, also referred to as bearing creep. It is shown that an inner race defect can be identified efficiently at an early stage by employing well known...

  17. Simulation modeling of wheeled vehicle dynamics on the stand "Roller"

    Directory of Open Access Journals (Sweden)

    G. O. Kotiev

    2014-01-01

    Full Text Available The tests are an integral part of the wheeled vehicle design, manufacturing, and operation. The need for their conducting arises from the research and experimental activities to assess the qualitative and quantitative characteristics of the vehicles in general, as well as the individual components and assemblies. It is obvious that a variety of design features of wheeled vehicles request a development of methods both for experimental studies and for creating the original bench equipment for these purposes.The main positive feature of bench tests of automotive engineering is a broad capability to control the combinations of traction loads, speed rates, and external input conditions. Here, the steady state conditions can be used for a long time, allowing all the necessary measurements to be made, including those with video and photo recording experiment.It is known that the benefits of test "M" type (using a roller dynamometer include a wide range of test modes, which do not depend on the climatic conditions, as well as a capability to use a computer-aided testing programs. At the same time, it is known that the main drawback of bench tests of full-size vehicle is that the tire rolling conditions on the drum mismatch to the real road pavements, which are difficult to simulate on the drum surface. This problem can be solved owing to wheeled vehicle tests at the benches "Roller" to be, in efficiency, the most preferable research method. The article gives a detailed presentation of developed at BMSTU approach to its solving.Problem of simulation mathematical modeling has been solved for the vehicle with the wheel formula 8 × 8, and individual wheel-drive.The simulation results have led to the conclusion that the proposed principle to simulate a vehicle rolling on a smooth non-deformable support base using a bench " Roller " by simulation modeling is efficient.

  18. Evaluation Standard for Safety Coefficient of Roller Compacted Concrete Dam Based on Finite Element Method

    Directory of Open Access Journals (Sweden)

    Bo Li

    2014-01-01

    Full Text Available The lack of evaluation standard for safety coefficient based on finite element method (FEM limits the wide application of FEM in roller compacted concrete dam (RCCD. In this paper, the strength reserve factor (SRF method is adopted to simulate gradual failure and possible unstable modes of RCCD system. The entropy theory and catastrophe theory are used to obtain the ultimate bearing resistance and failure criterion of the RCCD. The most dangerous sliding plane for RCCD failure is found using the Latin hypercube sampling (LHS and auxiliary analysis of partial least squares regression (PLSR. Finally a method for determining the evaluation standard of RCCD safety coefficient based on FEM is put forward using least squares support vector machines (LSSVM and particle swarm optimization (PSO. The proposed method is applied to safety coefficient analysis of the Longtan RCCD in China. The calculation shows that RCCD failure is closely related to RCCD interface strength, and the Longtan RCCD is safe in the design condition. Considering RCCD failure characteristic and combining the advantages of several excellent algorithms, the proposed method determines the evaluation standard for safety coefficient of RCCD based on FEM for the first time and can be popularized to any RCCD.

  19. Roller skating--is it a dangerous sport?

    Science.gov (United States)

    Tse, P Y; Shen, W Y; Chan, K M; Leung, P C

    1987-01-01

    A prospective survey of 111 cases of roller skating injuries within one year are reported. Males were more commonly injured than females. There was a high incidence (86%) of serious injuries, 28% of which required surgical treatment. The wrist (23%) was the commonest region involved, followed by the shoulder (20%), the elbow (15%) and the ankle (12%). Collision with other skaters and loss of control were the main factors leading to injury. Better rink discipline, instruction classes and safety publicity should be helpful in minimising accidents. Images Fig. 2 & Fig. 3 PMID:3676638

  20. Cylindrical acoustic levitator/concentrator

    Science.gov (United States)

    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.

  1. Visualization and prediction of porosity in roller compacted ribbonswith near infrared chemical imaging (NIR-CI)

    DEFF Research Database (Denmark)

    Khorasani, Milad Rouhi; Amigo Rubio, Jose Manuel; Sonnergaard, Jørn

    2015-01-01

    The porosity of roller compacted ribbon is recognized as an important critical quality attribute which has a huge impact on the final product quality. The purpose of this study was to investigate the use of near-infrared chemical imaging (NIR-CI) for porosity estimation of ribbons produced...... and control of continuously operating roller compaction line....

  2. Design rules for out-of-plane stability of roller bent steel arches with FEM

    NARCIS (Netherlands)

    Spoorenberg, R.C.; Snijder, H.H.; Hoenderkamp, J.C.D.; Beg, D.

    2012-01-01

    This paper describes a numerical investigation into the out-of-plane buckling behavior of freestanding roller bent steel arches. As roller bent arches have structural imperfections which differ considerably from those of hot-rolled or welded sections, specific attention is paid to their inclusion in

  3. A Methodology of Designing the Teeth Conjugation in a Planetary Roller Screw

    Directory of Open Access Journals (Sweden)

    Lisowski Filip

    2016-12-01

    Full Text Available The paper presents the methodology for designing the teeth conjunction of planetary gears in the planetary roller screw mechanism. A function of the planetary gears is to synchronize an operation of rollers in order to avoid axial displacements. A condition of the correct operation is no axial movement of rollers in relation to the nut. The planetary gears are integral parts of rollers and therefore an operation of the gear transmissions has a direct impact on cooperation of the screw, rollers and the nut. The proper design of gear engagements is essential for reducing slippage on surfaces of the cooperating threaded elements. For this purpose, in a designing method, both the limitations of operation and kinematic conditions of rollers’ operation have to be taken into account.

  4. High-energy roller injuries to the upper extremity.

    Science.gov (United States)

    Askins, G; Finley, R; Parenti, J; Bush, D; Brotman, S

    1986-12-01

    Eleven cases of high-energy industrial roller injuries treated between 1980 and 1984 were retrospectively reviewed. The dominant extremity was affected in nine. Six patients sustained fractures and/or dislocations, and three of these patients required fasciotomies for clinical signs of impending compartment syndromes. All fracture/dislocations, with the exception of a scapula fracture, anterior dislocation of a thumb interphalangeal joint, and a fractured coronoid process of the ulna, required open reduction with internal fixation. Three patients required split-thickness skin grafting for extensive skin degloving. Two patients required immediate amputation. Late sequelae included prolonged edema, nutritional depletion, neuroma formation of the superficial branch of the radial nerve, late carpal tunnel syndrome, and partial brachial plexus palsy. Industrial roller injuries continue to be an occupational hazard associated with more severe crushing trauma than the low-energy wringer washer injuries first described by MacCollum (11). Attention must be paid to the treatment of crushed skin, muscle, and nerves, fracture stabilization, nutritional support, and occupational therapy. Concurrent monitoring for signs of a developing compartment syndrome and complications of rhabdomyolysis is essential.

  5. Hot Ductility Behavior of an 8 Pct Cr Roller Steel

    Science.gov (United States)

    Wang, Zhenhua; Sun, Shuhua; Shi, Zhongping; Wang, Bo; Fu, Wantang

    2015-04-01

    The hot ductility of an 8 pct Cr roller steel was determined between 1173 K and 1473 K (900 °C and 1200 °C) at strain rates of 0.01 to 10 s-1 through tensile testing. The fracture morphology was observed using scanning electron microscopy, and the microstructure was examined through optical microscopy and transmission electron microscopy. The dependence of the hot ductility behavior on the deformation conditions, grain size, and precipitation was analyzed. The relationship between the reduction in area and the natural logarithm of the Zener-Hollomon parameter (ln Z) was found to be a second-order polynomial. When ln Z was greater than 40 s-1, the hot ductility was poor and fracture was mainly caused by incompatible deformation between the grains. When ln Z was between 32 and 40 s-1, the hot ductility was excellent and the main fracture mechanism was void linking. When ln Z was below 32 s-1, the hot ductility was poor and fracture was mainly caused by grain boundary sliding. A fine grain structure is beneficial for homogenous deformation and dynamic recrystallization, which induces better hot ductility. The effect of M7C3 carbide particles dispersed in the matrix on the hot ductility was small. The grain growth kinetics in the 8 pct Cr steel were obtained between 1373 K and 1473 K (1100 °C and 1200 °C). Finally, optimized preheating and forging procedures for 8 pct Cr steel rollers are provided.

  6. Telescoping cylindrical piezoelectric fiber composite actuator assemblies

    Science.gov (United States)

    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.

  7. Filling of charged cylindrical capillaries

    NARCIS (Netherlands)

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

    2014-01-01

    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

  8. Optics Demonstrations Using Cylindrical Lenses

    Science.gov (United States)

    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…

  9. Dismantling OPAL's cylindrical magnet core

    CERN Multimedia

    Laurent Guiraud

    2001-01-01

    Lifting a handling device for dismounting the pressure bells, which are inside the cylindrical magnet coil on the central section of OPAL, on the right part of the photo. OPAL was a detector on the LEP accelerator, which ran from 1989 to 2000.

  10. Cylindrical thin-shell wormholes

    International Nuclear Information System (INIS)

    Eiroa, Ernesto F.; Simeone, Claudio

    2004-01-01

    A general formalism for the dynamics of nonrotating cylindrical thin-shell wormholes is developed. The time evolution of the throat is explicitly obtained for thin-shell wormholes whose metric has the form associated with local cosmic strings. It is found that the throat collapses to zero radius, remains static, or expands forever, depending only on the sign of its initial velocity

  11. Hydrodynamic bearings

    CERN Document Server

    Bonneau, Dominique; Souchet, Dominique

    2014-01-01

    This Series provides the necessary elements to the development and validation of numerical prediction models for hydrodynamic bearings. This book describes the rheological models and the equations of lubrication. It also presents the numerical approaches used to solve the above equations by finite differences, finite volumes and finite elements methods.

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

    Science.gov (United States)

    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

  13. Homotheties of cylindrically symmetric static spacetimes

    International Nuclear Information System (INIS)

    Qadir, A.; Ziad, M.; Sharif, M.

    1998-08-01

    In this note we consider the homotheties of cylindrically symmetric static spacetimes. We find that we can provide a complete list of all metrics that admit non-trivial homothetic motions and are cylindrically symmetric static. (author)

  14. Armed rollers: does nestling's vomit function as a defence against predators?

    Directory of Open Access Journals (Sweden)

    Deseada Parejo

    Full Text Available Chemical defences against predators are widespread in the animal kingdom although have been seldom reported in birds. Here, we investigate the possibility that the orange liquid that nestlings of an insectivorous bird, the Eurasian roller (Coracias garrulus, expel when scared at their nests acts as a chemical defence against predators. We studied the diet of nestling rollers and vomit origin, its chemical composition and deterrent effect on a mammal generalist predator. We also hypothesized that nestling rollers, as their main prey (i.e. grasshoppers do from plants, could sequester chemicals from their prey for their use. Grasshoppers, that also regurgitate when facing to a threat, store the harmful substances used by plants to defend themselves against herbivores. We found that nestling rollers only vomit after being grasped and moved. The production of vomit depended on food consumption and the vomit contained two deterrent chemicals (hydroxycinnamic and hydroxybenzoic acids stored by grasshoppers and used by plants to diminish herbivory, suggesting that they originate from the rollers' prey. Finally, we showed for the first time that the oral secretion of a vertebrate had a deterrent effect on a model predator because vomit of nestling rollers made meat distasteful to dogs. These results support the idea that the vomit of nestling rollers is a chemical defence against predators.

  15. The System of Simulation and Multi-objective Optimization for the Roller Kiln

    Science.gov (United States)

    Huang, He; Chen, Xishen; Li, Wugang; Li, Zhuoqiu

    It is somewhat a difficult researching problem, to get the building parameters of the ceramic roller kiln simulation model. A system integrated of evolutionary algorithms (PSO, DE and DEPSO) and computational fluid dynamics (CFD), is proposed to solve the problem. And the temperature field uniformity and the environment disruption are studied in this paper. With the help of the efficient parallel calculation, the ceramic roller kiln temperature field uniformity and the NOx emissions field have been researched in the system at the same time. A multi-objective optimization example of the industrial roller kiln proves that the system is of excellent parameter exploration capability.

  16. A roller chain drive model including contact with guide-bars

    DEFF Research Database (Denmark)

    Pedersen, Sine Leergaard; Hansen, John Michael; Ambrósio, J. A. C.

    2004-01-01

    A model of a roller chain drive is developed and applied to the simulation and analysis of roller chain drives of large marine diesel engines. The model includes the impact with guide-bars that are the motion delimiter components on the chain strands between the sprockets. The main components...... and the sprocket centre, i.e. a constraint is added when such distance is less than the pitch radius. The unilateral kinematic constraint is removed when its associated constraint reaction force, applied on the roller, is in the direction of the root of the sprocket teeth. In order to improve the numerical...

  17. Edgewise vibration control of wind turbine blades using roller and liquid dampers

    DEFF Research Database (Denmark)

    Zhang, Zili; Nielsen, Søren R.K.

    2014-01-01

    suppressing edgewise vibrations. The roller dampers are more volumetrically efficient due to the higher mass density of the steel comparing with the liquid. On the other hand, TLCDs have their advantage that it is easier to specify the optimum damping of the damper by changing the opening ratio of the orifice......This paper deals with the passive vibration control of edgewise vibrations by means of roller dampers and tuned liquid column dampers (TLCDs). For a rotating blade, the large centrifugal acceleration makes it possible to use roller dampers or TLCDs with rather small masses for effectively...

  18. Cylindrical collapse and gravitational waves

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, L [Escuela de FIsica, Faculdad de Ciencias, Universidad Central de Venezuela, Caracas, Venezuela (Venezuela); Santos, N O [Universite Pierre et Marie Curie, CNRS/FRE 2460 LERMA/ERGA, Tour 22-12, 4eme etage, BoIte 142, 4 place Jussieu, 75252 Paris Cedex 05 (France); Laboratorio Nacional de Computacao Cientifica, 25651-070 Petropolis RJ (Brazil); Centro Brasileiro de Pesquisas Fisicas, 22290-180 Rio de Janeiro RJ (Brazil)

    2005-06-21

    We study the matching conditions for a collapsing anisotropic cylindrical perfect fluid, and we show that its radial pressure is non-zero on the surface of the cylinder and proportional to the time-dependent part of the field produced by the collapsing fluid. This result resembles the one that arises for the radiation-though non-gravitational-in the spherically symmetric collapsing dissipative fluid, in the diffusion approximation.

  19. Cracking of anisotropic cylindrical polytropes

    Energy Technology Data Exchange (ETDEWEB)

    Mardan, S.A. [University of the Management and Technology, Department of Mathematics, Lahore (Pakistan); Azam, M. [University of Education, Division of Science and Technology, Lahore (Pakistan)

    2017-06-15

    We study the appearance of cracking in charged anisotropic cylindrical polytropes with generalized polytropic equation. We investigate the existence of cracking in two different kinds of polytropes existing in the literature through two different assumptions: (a) local density perturbation with conformally flat condition, and (b) perturbing polytropic index, charge and anisotropy parameters. We conclude that cracking appears in both kinds of polytropes for a specific range of density and model parameters. (orig.)

  20. Alred Roller – An Innovator and a Traditionalist

    Directory of Open Access Journals (Sweden)

    Zavarský Ján

    2017-12-01

    Full Text Available This study focuses on the scenographer Alfred Roller (1864–1935 and his productions of Wagner’s musical dramas, with emphasis on Tristan and Isolde and Parsifal. It places Roller’s aesthetics in a historical, aesthetic, and artistic context, points to his inspiration by the Swiss scenography reformer Adolphe Appia, and cooperation with the music composer and conductor Gustav Mahler in the Vienna Court Opera. The text analyses the specifics of Roller’s scenography, which diverged from illusive stage and used light work as an important production principle. It concludes with a summary of the effect of Roller’s aesthetics on Ľudovít Hradský, the first leader of the production team at the Slovak National Theatre (1923–1928. The visual aspects of the Slovak National Theatre’s productions in that period were strongly inspired by expressionism and Art Nouveau, which were typical of German theatre at that time.

  1. Bearing structures

    International Nuclear Information System (INIS)

    Lee, A.S.; Preece, G.E.

    1988-01-01

    A hydrostatic bearing for the lower end of the vertical shaft of a sodium pump comprises a support shell encircling the shaft and a bush located between the shell and shaft. Liquid sodium is fed from the pump outlet to the bush/shaft and bush/shell interfaces to provide hydrostatic support. The bush outer surface and the shell inner surface are of complementary part-spherical shape and the bush floats relative to the shaft so that the bush can align itself with the shaft axis. Monitoring of the relative rotational speed of the bush with respect to the shaft (such rotation being induced by the viscous drag forces present) is also performed for the purposes of detecting abnormal operation of the bearing or partial seizure, at least one magnet is rotatable with the bush, and a magnetic sensor provides an output having a frequency related to the speed of the bush. (author)

  2. Cylindrical Piezoelectric Fiber Composite Actuators

    Science.gov (United States)

    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.

  3. Plastic buckling of cylindrical shells

    International Nuclear Information System (INIS)

    Bandyopadhyay, K.; Xu, J.; Shteyngart, S.; Eckert, H.

    1994-01-01

    Cylindrical shells exhibit buckling under axial loads at stresses much less than the respective theoretical critical stresses. This is due primarily to the presence of geometrical imperfections even though such imperfections could be very small (e.g., comparable to thickness). Under internal pressure, the shell regains some of its buckling strength. For a relatively large radius-to-thickness ratio and low internal pressure, the effect can be reasonably estimated by an elastic analysis. However, for low radius-to-thickness ratios and greater pressures, the elastic-plastic collapse controls the failure load. in order to quantify the elastic-plastic buckling capacity of cylindrical shells, an analysis program was carried out by use of the computer code BOSOR5 developed by Bushnell of Lockheed Missiles and Space Company. The analysis was performed for various radius-to-thickness ratios and imperfection amplitudes. The purpose of the analytical program was to compute the buckling strength of underground cylindrical tanks, that are used for storage of nuclear wastes, for realistic geometric imperfections and internal pressure loads. This paper presents the results of the elastic-plastic analyses and compares them with other available information for various pressure loads

  4. Journal Bearings

    Directory of Open Access Journals (Sweden)

    Renato Brancati

    1999-01-01

    determined after acquiring and analysing the orbits described by the journal axis for assigned unbalance values in different operating conditions. Analysis of the results shows some particular operating features that were not entirely predicted by the theoretical model and which may give rise to malfunctions in the rotor-tilting pad bearings system. The tests were carried out in the rotor dynamics laboratory of the Dipartimento di Ingegneria Meccanica per l'Energetica at the University of Naples.

  5. Radiometric and ultrasonic testing of vibrating roller compacting effects

    International Nuclear Information System (INIS)

    Prikryl, F.; Habarta, J.; Kovarikova, E.

    1977-01-01

    A hole was filled with two layers of concrete mixture. Each layer was compacted using a Dynapac CA 25 vibrating roller 10,000 kg in weight, operating with a frequency of 30 Hz. A concrete block thus produced had dimensions of 11.0x2.5 m and a height of 1.6 m. After the concrete block hardening (roughly 120 days) drill cores were bored and bulk density was determined using nondestructive methods. Bulk density determination of the concrete between the drill cores was conducted using a 137 Cs emitter of an activity of 89 GBq, a FHZ-88b Geiger-Mueller counter was used as the detector. The emitter and detector were placed to touch the bore wall and were lowered to different depths in 10 cm increments. 10 count rate values were measured in each depth. The measurement time was chosen such that the decay statistical error did not exceed 1;. Bulk density of the individual segments of the drill cores was determined using 60 Co of an activitBy of 55 Mq as the radiation source and a TESLA 20/100 GWl GM counter as the detector. The detector operating voltage was 1240 V. Ultrasonic measurements were conducted using the USME-5 instrument. The measured bulk density values show that the compacting of a concrete layer 80 cm in thickness using a vibrating roller is sufficiently efficient. Both nondestructive methods were well proven, the results show that bulk density values in different depths differ due to concrete moisture content. (J.P.)

  6. Control rod upper pin and roller removal and replacement

    International Nuclear Information System (INIS)

    Giordano, B.

    1995-01-01

    There has been increasing utility interest in removing cobalt sources as a means to minimize dose rates and shipping costs associated with operations, maintenance, shipping and radioactive waste disposal. This activation product accounts for approximately 80% of the dose rates at a plant. Estimates suggest that older (original equipment) control rod blades (CRBs) using stellite rollers and Haynes Alloy 25 pins can contribute as much as 43% of the cobalt in the plant. Since CRBs are the most concentrated source of cobalt in the reactor vessel, pin and roller (P ampersand R) replacement will provide significant reductions in cobalt-60 levels. The reductions will be measurable within 2 years, and should plateau within 5 to 6 years. This paper described a new, simple, cost effective, field proven in-situ method to replace these high source term contributing components and return the CRB to the reactor core for continued service. The paper also briefly describes a methodology that has been developed to estimate the labor and material costs along with a man-rem dollar savings for removal of the upper P ampersand Rs from in-service CRBs purchased prior to 1982. This method permits comparison to the cost of early replacement of CRBs. The result of this study is an EXCEL spreadsheet cost/benefit analysis that can be made plant specific by incorporation of plant data. The Analysis shows that the removal of P ampersand Rs can be beneficial for a Co-60 contribution as low as 5-10%. Recent interest by non-utility radioactive material users in obtaining the removed P ampersand Rs may further increase the benefit and reduce the cost associated with in-situ removal

  7. Camshaft bearing arrangement

    Energy Technology Data Exchange (ETDEWEB)

    Aoi, K.; Ozawa, T.

    1986-06-10

    A bearing arrangement is described for the camshaft of an internal combustion engine or the like which camshaft is formed along its length in axial order with a first bearing surface, a first cam lobe, a second bearing surface, a second cam lobe, a third bearing surface, a third cam lobe and a fourth bearing surface, the improvement comprising first bearing means extending around substantially the full circumference of the first bearing surface and journaling the first bearing surface, second bearing means extending around substantially less than the circumference of the second bearing surface and journaling the second bearing surface, third bearing means extending around substantially less than the circumference of the third bearing surface and journaling the third bearing surface, and fourth bearing means extending around substantially the full circumference of the fourth bearing surface and journaling the first bearing surface.

  8. The thermodynamic properties of a new type catcher bearing used in active magnetic bearings system

    International Nuclear Information System (INIS)

    Jin, Chaowu; Zhu, Yili; Xu, Longxiang; Xu, Yuanping; Zheng, Yantong

    2015-01-01

    Normally a rotor levitated by active magnetic bearings (AMBs) system would rotate without contacting with any stator component, but the possibility still remains that the supporting force might lose temporarily or permanently, thus requiring the Catcher bearings (CBs) to provide backup protection in case of the failure of AMBs. A new type CB with two separate rolling element bearing series could have the speed distribution between the inner race and intermediate race according to certain ratio, in which the speed of each roller element bearing decreases with the limit speed of the whole CB increasing, offering high capability to sustain its initial rotation speed. Based on the theory of heat transfer, tribology, and rotor dynamics, this paper analyzes the thermal structure of double-decker catcher bearing (DDCB) and single-decker catcher bearing (SDCB), respectively. Through this structure, the thermal resistances and equations of heat transfer can be obtained. Then we calculate the friction heat and temperature distribution in the various CBs upon rotor's dropping on SDCB or DDCB, followed by the discussion on the CBs temperature rise's effects on lubrication conditions and rotor dynamics parameters. Finally various experiments are carried out to measure the temperature rise of different CBs. The results obtained validate the theoretical analysis and also provide main methods to reduce heat generation. Using DDCB is proved to be effective to reduce the temperature rise. - Highlights: • The DDCB is a more suitable catcher bearing for AMBs. • Compared to SDCB, using DDCB, the temperature rise can decrease in the same states. • A lower viscosity of lubricant may induce a lower temperature rise. • The inner raceway temperature of the first layer bearing is the highest. • Reducing the unbalance mass of the rotor is a method to decrease the temperature rise

  9. Simulation-driven machine learning: Bearing fault classification

    Science.gov (United States)

    Sobie, Cameron; Freitas, Carina; Nicolai, Mike

    2018-01-01

    Increasing the accuracy of mechanical fault detection has the potential to improve system safety and economic performance by minimizing scheduled maintenance and the probability of unexpected system failure. Advances in computational performance have enabled the application of machine learning algorithms across numerous applications including condition monitoring and failure detection. Past applications of machine learning to physical failure have relied explicitly on historical data, which limits the feasibility of this approach to in-service components with extended service histories. Furthermore, recorded failure data is often only valid for the specific circumstances and components for which it was collected. This work directly addresses these challenges for roller bearings with race faults by generating training data using information gained from high resolution simulations of roller bearing dynamics, which is used to train machine learning algorithms that are then validated against four experimental datasets. Several different machine learning methodologies are compared starting from well-established statistical feature-based methods to convolutional neural networks, and a novel application of dynamic time warping (DTW) to bearing fault classification is proposed as a robust, parameter free method for race fault detection.

  10. Standard test method for measurement of web/roller friction characteristics

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2003-01-01

    1.1 This test method covers the simulation of a roller/web transport tribosystem and the measurement of the static and kinetic coefficient of friction of the web/roller couple when sliding occurs between the two. The objective of this test method is to provide users with web/roller friction information that can be used for process control, design calculations, and for any other function where web/roller friction needs to be known. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  11. Roller-coaster Ride to, Relief From TMJ | NIH MedlinePlus the Magazine

    Science.gov (United States)

    ... on a roller coaster ride, seeking relief from temporomandibular joint (TMJ) disorder, which causes pain and, sometimes, dysfunction in the jaw joint and muscles of the neck, head, and face. She has endured: excruciating pain ...

  12. Cost of a roller skating rink to the local accident and emergency department.

    Science.gov (United States)

    Nayeem, N; Shires, S E; Porter, J E

    1990-01-01

    A 14 month retrospective study was undertaken to determine the cost implications of the opening of a roller skating rink to the local hospital accident and emergency department (A and E). A total of 398 patients attended following injury at the roller skating rink, of whom 384 were included in the study. The estimated cost of their injuries was determined by the hospital accounts department. The average cost per patient attending the A and E department following roller skating injury was about 100 pounds. The total cost to the A and E department of all injuries sustained at the rink over this period was 38,412 pounds. The cost implications of opening a roller skating rink for the A and E department are considerable. If proposals for self-budgeting are applied, A and E departments will have to seek additional funding if such leisure facilities are opened in their vicinity. PMID:2097020

  13. Phylogenetic relationships of rollers (Coraciidae) based on complete mitochondrial genomes and fifteen nuclear genes.

    Science.gov (United States)

    Johansson, Ulf S; Irestedt, Martin; Qu, Yanhua; Ericson, Per G P

    2018-04-06

    The rollers (Coraciidae) constitute a relative small avian family with ca. 12 species distributed in Africa, western and southern Eurasia, and eastern Australia. In this study we examine the phylogenetic relationships of all species currently recognized in the family, including two taxa whose taxonomic status is currently contested. By using shotgun sequencing on degraded DNA from museum study skins we have been able to recover complete mitochondrial genomes as well as 15 nuclear genes for in total 16 taxa. The gene sequences were analyzed both concatenated in a maximum likelihood framework as well in a species tree approach using MP-EST. The different analytical approaches yield similar, highly supported trees and support the current division of the rollers into two genera, Coracias and Eurystomus. The only conflict relates to the placement of the Blue-bellied Roller (C. cyanogaster), where the mitochondrial, and the concatenated nuclear and mitochondrial data set, place this taxon as sister to the other Coracias species, whereas nuclear data and the species tree analysis place it as the sister taxon of C. naevia and C. spatulatus. All analyses place the Eurasian roller (C. garrulus) with the two African species, Abyssinian Roller (C. abyssinica) and Liliac-breasted Roller (C. caudatus), and place this clade as the sister group to the Asian Coracias rollers. In addition, our results support a sister group relationship between the morphologically rather dissimilar Purple Roller (C. naevia) and Racquet-tailed Roller (C. spatulatus) and also support the division of Eurystomus in an African and an Asian clade. However, within the Asian clade the Azure Roller (E. azureus) from Halmahera appears to be nested within the Dollarbird (E. orientalis), indicating that that this taxon is a morphological divergent, but a rather recent offshoot, of the widespread Dollarbird. Similarly, the Purple-winged Roller (C. temminickii) from Sulawesi group together with C. benghalensis

  14. Improving feeding powder distribution to the compaction zone in the roller compaction.

    Science.gov (United States)

    Yu, Mingzhe; Omar, Chalak; Schmidt, Alexander; Litster, James D; Salman, Agba D

    2018-07-01

    In the roller compaction process, powder flow properties have a significant influence on the uniformity of the ribbon properties. The objective of this work was to improve the powder flow in the feeding zone by developing novel feeding guiders which are located in the feeding zone close to the rollers in the roller compactor (side sealing system). Three novel feeding guiders were designed by 3D printing and used in the roller compactor, aiming to control the amount of powder passing across the roller width. The new feeding guiders were used to guide more powder to the sides between the rollers and less powder to the centre comparing to the original feeding elements. Temperature profile and porosity across the ribbon width indicated the uniformity of the ribbon properties. Using the novel feeding guiders resulted in producing ribbons with uniform temperature profile and porosity distribution across the ribbon width. The design of the feeding guiders contributed to improving the tensile strength of the ribbons produced from the compaction stage as well as reducing the fines produced from the crushing stage. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Absorption factor for cylindrical samples

    International Nuclear Information System (INIS)

    Sears, V.F.

    1984-01-01

    The absorption factor for the scattering of X-rays or neutrons in cylindrical samples is calculated by numerical integration for the case in which the absorption coefficients of the incident and scattered beams are not equal. An extensive table of values having an absolute accuracy of 10 -4 is given in a companion report [Sears (1983). Atomic Energy of Canada Limited, Report No. AECL-8176]. In the present paper an asymptotic expression is derived for the absorption factor which can be used with an error of less than 10 -3 for most cases of interest in both neutron inelastic scattering and neutron diffraction in crystals. (Auth.)

  16. MacDonald Dam reconstruction : using roller-compacted concrete

    Energy Technology Data Exchange (ETDEWEB)

    O' Neil, E. [AMEC Earth and Environmental Ltd., Sydney, NS (Canada)

    2007-04-01

    Located in Nova Scotia, the MacDonald Dam was commissioned in 1928. The dam consists of a 122 metre-long, 16 metre-high concrete structure comprised of an intake structure, stoplog openings, and a 34 metre-long free-overflow spillway. A 488 metre-long power canal was added as an upgrade in the 1950s. This paper provided details of the roller-compact concrete (RCC) used in the dam's recent rehabilitation following a dam failure analysis in 2003 by Nova Scotia Power Inc. RCC was chosen to help keep the dam's construction project on schedule. The layout and cross-section of the spillway was selected with consideration given to the RCC placing operation. A lift thickness of 0.20 m was selected. A formed ogee crest consisting of conventional reinforced concrete was constructed on top of the RCC. The downstream steps of the spillway were also covered with cast-in-place concrete. A low level sluice was designed to resist the weight of the wet RCC. The design compressive strength of the RCC was 20 MPa. The forms used to support the cast-in-place facing concrete on the upstream face of the dam were constructed full height and were braced back to the downstream face of the existing concrete structure prior to the start of RCC placement. Formwork inserts were placed in the facing concrete as construction progressed. Crack inducers were pre-placed on the forms. Aggregates from a local source were transported to a pug mill as the RCC construction progressed. The RCC was spread into 0.20 m lifts using a small bull-dozer, and the facing concrete was vibrated into the lift below. RCC lifts were compacted using a 9 tonne vibratory drum roller. The RCC placing operation was completed over a period of 10 days. Following the completion of the RCC portion of the dam, the remainder of the cast-in-place concrete was completed. It was concluded that the RCC provided a durable, low-maintenance structure that was completed at a lower price and in a shorter time-frame than

  17. Study of hydrodynamic behaviour of large bearings depending on the viscosity of the lubricant

    Directory of Open Access Journals (Sweden)

    Barabas Sorin

    2017-01-01

    Full Text Available The research refers to study of hydrodynamic behavior of large bearings equipped with automatic lubrication system, where the liquid used may have a viscosity with variable values depending on the temperature or depending on the additive used. The introduction of additives with nanoparticles causes modification of viscosity and a significant reduction of friction coefficient. This study establishes a direct link between the friction, viscosity and tensions that occur in the contact area. Experimental studies confirm improving tribological properties of the contact area between the bearing rollers and raceways, through attracting nanoparticles on surfaces in contact and reducing friction coefficient. Accomplished finite element analysis showed decrease of the contact stresses, therefore decrease of the wear and increase the life of the bearing. Research has concluded that influencing viscosity and friction coefficient of lubricant can result in reducing wear of the bearing components, as well as increase the lifetime of bearing.

  18. The electrostatic cylindrical sheath in a plasma

    International Nuclear Information System (INIS)

    Wang Chunhua; Sun Xiaoxia; Bai Dongxue

    2004-01-01

    The electrostatic sheath with a cylindrical geometry in an ion-electron plasma is investigated. Assuming a Boltzmann response to electrons and cold ions with bulk flow, it is shown that the radius of the cylindrical geometry do not affect the sheath potential significantly. The authors also found that the sheath potential profile is steeper in the cylindrical sheath compared to the slab sheath. The distinct feature of the cylindrical sheath is that the ion density distribution is not monotonous. The sheath region can be divided into three regions, two ascendant regions and one descendant region. (author)

  19. Ni-Ti Next Generation Bearings for Space Applications

    Science.gov (United States)

    DellaCorte, Christopher

    2018-01-01

    NASA applications challenge traditional bearing materials. The rigors of launch often include heavy shock loads and exposure to corrosive environments (e.g., salt spray). Unfortunately, ball and roller bearings made from hardened steels are vulnerable to Brinell denting and rust which can limit performance and life. Ceramic materials can eliminate corrosion concerns but their high stiffness and extreme hardness actually makes denting problems worse. In this presentation, an emerging superelastic alloy, NiTi, is introduced for rolling element bearing applications. Through a decade of RD, NiTi alloy bearings have been put through a comprehensive series of life and performance tests. Hardness, corrosion, strength, stiffness, and rolling contact fatigue tests have been conducted and reported. Ball bearings ranging in size from 12 to 50mm bore have been successfully engineered and operated over a wide range of speeds and test conditions including being submerged in water. The combination of high hardness, moderate elastic modulus, low density, and intrinsic corrosion immunity provide new possibilities for mechanisms that operate under extreme conditions. Recent preliminary tests indicate that bearings can be made from NiTi alloys that are easily lubricated by conventional oils and greases and exhibit acceptable rolling contact fatigue resistance. This presentation introduces the NiTi materials systems and shows how NASA is using it to alleviate several specific problems encountered in advanced space applications.

  20. Diffusion from cylindrical waste forms

    International Nuclear Information System (INIS)

    Thomas, G.F.

    1985-05-01

    The diffusion of a single component material from a finite cylindrical waste form, initially containing a uniform concentration of the material, is investigated. Under the condition that the cylinder is maintained in a well-stirred bath, expressions for the fractional inventory leached and the leach rate are derived with allowance for the possible permanent immobilization of the diffusant through its decay to a stable product and/or its irreversible reaction with the waste form matrix. The usefulness of the reported results in nuclear waste disposal applications is emphasized. The results reported herein are related to those previously derived at Oak Ridge National Laboratory by Bell and Nestor. A numerical scheme involving the partial decoupling of nested infinite summations and the use of rapidly converging rational approximants is recommended for the efficient implementation of the expressions derived to obtain reliable estimates of the bulk diffusion constant and the rate constant describing the diffusant-waste form interaction from laboratory data

  1. Spiral modes in cold cylindrical systems

    International Nuclear Information System (INIS)

    Robe, H.

    1975-01-01

    The linearized hydrodynamical equations governing the non-axisymmetric free modes of oscillation of cold cylindrical stellar systems are separated in cylindrical coordinates and solved numerically for two models. Short-wavelength unstable modes corresponding to tight spirals do not exist; but there exists an unstable growing mode which has the form of trailing spirals which are quite open. (orig.) [de

  2. A method of increasing the depth of the plastically deformed layer in the roller burnishing process

    Science.gov (United States)

    Kowalik, Marek; Trzepiecinski, Tomasz

    2018-05-01

    The subject of this paper is an analysis of the determination of the depth of the plastically deformed layer in the process of roller burnishing a shaft using a newly developed method in which a braking moment is applied to the roller. It is possible to increase the depth of the plastically deformed layer by applying the braking moment to the roller during the burnishing process. The theoretical considerations presented are based on the Hertz-Bielayev and Huber-Mises theories and permit the calculation of the depth of plastic deformation of the top layer of the burnished shaft. The theoretical analysis has been verified experimentally and using numerical calculations based on the finite element method using the Msc.MARC program. Experimental tests were carried out on ring-shaped samples made of C45 carbon steel. The samples were burnished at different values of roller force and different values of braking moment. A significant increase was found in the depth of the plastically deformed surface layer of roller burnished shafts. Usage of the phenomenon of strain hardening of steel allows the technology presented here to increase the fatigue life of the shafts.

  3. Do Maximal Roller Skiing Speed and Double Poling Performance Predict Youth Cross-Country Skiing Performance?

    Directory of Open Access Journals (Sweden)

    Roland Stöggl, Erich Müller, Thomas Stöggl

    2017-09-01

    Full Text Available The aims of the current study were to analyze whether specific roller skiing tests and cycle length are determinants of youth cross-country (XC skiing performance, and to evaluate sex specific differences by applying non-invasive diagnostics. Forty-nine young XC skiers (33 boys; 13.8 ± 0.6 yrs and 16 girls; 13.4 ± 0.9 yrs performed roller skiing tests consisting of both shorter (50 m and longer durations (575 m. Test results were correlated with on snow XC skiing performance (PXC based on 3 skating and 3 classical distance competitions (3 to 6 km. The main findings of the current study were: 1 Anthropometrics and maturity status were related to boys’, but not to girls’ PXC; 2 Significant moderate to acceptable correlations between girls’ and boys’ short duration maximal roller skiing speed (double poling, V2 skating, leg skating and PXC were found; 3 Boys’ PXC was best predicted by double poling test performance on flat and uphill, while girls’ performance was mainly predicted by uphill double poling test performance; 4 When controlling for maturity offset, boys’ PXC was still highly associated with the roller skiing tests. The use of simple non-invasive roller skiing tests for determination of PXC represents practicable support for ski clubs, schools or skiing federations in the guidance and evaluation of young talent.

  4. Assessment of solid microneedle rollers to enhance transmembrane delivery of doxycycline and inhibition of MMP activity.

    Science.gov (United States)

    Omolu, Abbie; Bailly, Maryse; Day, Richard M

    2017-11-01

    Many chronic wounds exhibit high matrix metalloproteinase (MMP) activity that impedes the normal wound healing process. Intradermal delivery (IDD) of sub-antimicrobial concentrations of doxycycline, as an MMP inhibitor, could target early stages of chronic wound development and inhibit further wound progression. To deliver doxycycline intradermally, the skin barrier must be disrupted. Microneedle rollers offer a minimally invasive technique to penetrate the skin by creating multiple microchannels that act as temporary conduits for drugs to diffuse through. In this study, an innovative and facile approach for delivery of doxycycline across Strat-M TM membrane was investigated using microneedle rollers. The quantity and rate of doxycycline diffusing through the micropores directly correlated with increasing microneedle lengths (250, 500 and 750 μm). Treatment of Strat-M TM with microneedle rollers resulted in a reduction in fibroblast-mediated collagen gel contraction and MMP activity compared with untreated Strat-M TM . Our results show that treatment of an epidermal mimetic with microneedle rollers provides sufficient permeabilization for doxycycline diffusion and inhibition of MMP activity. We conclude that microneedle rollers are a promising, clinically ready tool suitable for delivery of doxycycline intradermally to treat chronic wounds.

  5. Edgewise vibration control of wind turbine blades using roller and liquid dampers

    International Nuclear Information System (INIS)

    Zhang, Z L; Nielsen, S R K

    2014-01-01

    This paper deals with the passive vibration control of edgewise vibrations by means of roller dampers and tuned liquid column dampers (TLCDs). For a rotating blade, the large centrifugal acceleration makes it possible to use roller dampers or TLCDs with rather small masses for effectively suppressing edgewise vibrations. The roller dampers are more volumetrically efficient due to the higher mass density of the steel comparing with the liquid. On the other hand, TLCDs have their advantage that it is easier to specify the optimum damping of the damper by changing the opening ratio of the orifice. In this paper, 2-DOF nonlinear models are suggested for tuning a roller damper or a TLCD attached to a rotating wind turbine blade, ignoring the coupling between the blade and the tower. The decoupled optimization is verified by incorporating the optimized damper into a more sophisticated 13- DOF wind turbine model with due consideration of the coupled blade-tower-drivetrain vibrations, quasi-static aeroelasticity as well as a collective pitch controller. Performances of the dampers are compared in terms of the control efficiency and the practical applications. The results indicate that roller dampers and TLCDs at optimal tuning can effectively suppress the dynamic response of wind turbine blades

  6. A remote engineering solution for automating a roller hearth kiln

    Directory of Open Access Journals (Sweden)

    João Bosco da Mota Alves

    2008-07-01

    Full Text Available Remote engineering (also known as online engineering may be defined as a combination of control engineering and telematics. In this area, specific activities require computacional skills in order to develop projects where electrical devives are monitored and / or controlled, in an intercative way, through a distributed network (e.g. Intranet or Internet. In our specific case, we will be dealing with an industrial plant. Within the last few years, there has been an increase in the number of activities related to remote engineering, which may be connected to the phenomenon of the large extension experienced by the Internet (e.g. bandwith, number of users, development tools, etc.. This increase opens new and future possibilities to the implementation of advance teleworking (or e-working positions. In this paper we present the architecture for a remote application, accessible through the Internet, able to monitor and control a roller hearth kiln, used in a ceramics industry for firing materials. The proposed architecture is based on a micro web server, whose main function is to monitor and control the firing process, by reading the data from a series of temperature sensors and by controlling a series of electronic valves and servo motors. This solution is also intended to be a low-cost alternative to other potential solutions. The temperature readings are obtained through K-type thermopairs and the gas flow is controlled through electrovalves. As the firing process should not be stopped before its complete end, the system is equipped with a safety device for that specific purpose. For better understanding the system to be automated and its operation we decided to develop a scale model (100:1 and experiment on it the devised solution, based on a Micro Web Server.

  7. Dynamic Characteristics of Rotors on Passive and Active Thrust Fluid-film Bearings with Fixed Pads

    Directory of Open Access Journals (Sweden)

    Babin Alexander

    2018-01-01

    Full Text Available Application of fluid-film bearings in rotor machines in many cases could have no alternative due to obvious advantages when compared to roller element bearings. Integration of information technology in mechanical engineering resulting in emergence of a new field of research – mechatronic bearings which allowed tracking condition of the most important parts of a machine and adjusting operational parameters of the system. Application of servo valves to control the flow rate through a fluid-film bearing is the most universal and simple way of rotor’s position control due to relative simplicity of modelling and absence of need to radically change the design of conventional hydrodynamic bearings. In the present paper numerical simulations of passive (conventional as opposed to mechatronic and active hybrid thrust fluid-film bearings with a central feeding chamber are presented, that are parts of a mechatronic rotor-bearing node. Numerical model of an active thrust bearing is based on solution of equations of hydrodynamics, rotor dynamics and an additional model of a servo valve. Various types of control have been investigated: P, PI and PID control, and the dynamic behaviour of a system has been estimated under various loads, namely static, periodic and impulse. A design of a test rig has been proposed to study passive and active thrust fluid-film bearings aimed at, among other, validation of numerical results of active bearings simulation.

  8. Case histories of roller cone core bit application in crystalline rock

    International Nuclear Information System (INIS)

    Dahlem, J.S.

    1988-01-01

    The increased interest in deep crystalline rock drilling projects has resulted in a requirement for premium coring bits which are effective in such a harsh and abrasive environment. Hard formation roller cone insert bits have traditionally and constantly performed well in crystalline rock. As a result, the application of state of the art roller cone rock bit technology to the design and development of core bits has made crystalline coring projects more viable than ever before. This paper follows the development of roller cone core bits by examining their use on project such as HDR (Hot Dry Rock, Los Alamos); NAGRA (Nuclear Waste Disposal Wells in Switzerland); Camborne School of Mines Geothermal Project in Cornwall, UK; Deep Gas Project in Sweden; and the KTB Deep Drilling Project in West Germany

  9. Simulation of accelerated strip cooling on the hot rolling mill run-out roller table

    International Nuclear Information System (INIS)

    Muhin, U.; Belskij, S.; Makarov, E.; Koinov, T.

    2013-01-01

    Full text: A mathematical model of the thermal state of the metal on the run-out roller table of a continuous wide hot-strip mill is presented. The mathematical model takes into account the heat generation during the polymorphic γ → α transformation of super cooled austenite phase and the influence of chemical composition on the physical properties of the steel. The model allows the calculation of modes of accelerated cooling of strips on the run-out roller table of a continuous wide hot strip mill. Winding temperature calculation error does not exceed 20 °C for 98.5 % of the strips from low-carbon and low-alloyed steels. key words: hot rolled, wide-strip, accelerated cooling, run-out roller table, polymorphic transformation, mathematical modeling

  10. Modeling of Comparative Performance of Asphalt Concrete under Hammer, Gyratory, and Roller Compaction

    Directory of Open Access Journals (Sweden)

    Saad I. Sarsam

    2016-11-01

    Full Text Available The main objective of this study is to develop predictive models using SPSS software (version 18 for Marshall Test results of asphalt mixtures compacted by Hammer, Gyratory, and Roller compaction. Bulk density of (2.351 gm/cc, at OAC of (4.7 % was obtained as a benchmark after using Marshall Compactor as laboratory compactive effort with 75-blows. Same density was achieved by Roller and Gyratory Compactors using its mix designed methods. A total of (75 specimens, for Marshall, Gyratory, and Roller Compactors have been prepared, based on OAC of (4.7 % with an additional asphalt contents of more and less than (0.5 % from the optimum value. All specimens have been subjected to Marshall Test. Mathematical models obtained indicated that variation of Marshall Stiffness is based on the variation of air voids. All of these models depend on asphalt cement content too.

  11. Roller pressure algometry as a new tool for assessing dynamic pressure sensitivity in migraine

    DEFF Research Database (Denmark)

    Guerrero-Peral, Ángel L.; Ruíz, Marina; Barón, Johanna

    2018-01-01

    from 500 to 5300 g. Each roller was moved at a speed of 0.5 cm/sec over a 60 mm horizontal line covering the temporalis muscle. The dynamic pain threshold (the pressure level of the first painful roller) and pain elicited during the pain threshold (roller evoked pain) were determined. Static pressure...... pain thresholds were assessed over the temporalis muscle, C5/C6 joint, second metacarpal, and tibialis anterior. Results Side-to-side consistency between dynamic pain threshold (rs = 0.769, p ... was slightly stronger in chronic migraine. Pain during dynamic pain threshold was negatively associated with widespread pressure pain thresholds (-0.336 

  12. An investigation into the impact of magnesium stearate on powder feeding during roller compaction.

    Science.gov (United States)

    Dawes, Jason; Gamble, John F; Greenwood, Richard; Robbins, Phil; Tobyn, Mike

    2012-01-01

    A systematic evaluation on the effect of magnesium stearate on the transmission of a placebo formulation from the hopper to the rolls during screw fed roller compaction has been carried out. It is demonstrated that, for a system with two 'knurled' rollers, addition of 0.5% w/w magnesium stearate can lead to a significant increase in ribbon mass throughput, with a consequential increase in roll gap, compared to an unlubricated formulation (manufactured at equivalent process conditions). However, this effect is reduced if one of the rollers is smooth. Roller compaction of a lubricated formulation using two smooth rollers was found to be ineffective due to a reduction in friction at the powder/roll interface, i.e. powder was not drawn through the rollers leading to a blockage in the feeding system. An increase in ribbon mass throughput could also be achieved if the equipment surfaces were pre-lubricated. However this increase was found to be temporary suggesting that the residual magnesium stearate layer was removed from the equipment surfaces. Powder sticking to the equipment surfaces, which is common during pharmaceutical manufacturing, was prevented if magnesium stearate was present either in the blend, or at the roll surface. It is further demonstrated that the influence of the hopper stirrer, which is primarily used to prevent bridge formation in the hopper and help draw powder more evenly into the auger chamber, can lead to further mixing of the formulation, and could therefore affect a change in the lubricity of the carefully blended input material.

  13. Skateboarding: more dangerous than roller skating or in-line skating.

    Science.gov (United States)

    Osberg, J S; Schneps, S E; Di Scala, C; Li, G

    1998-10-01

    To describe the circumstances, severity, and outcomes of skating-related injuries among children admitted to trauma centers. A cross-sectional comparison of roller skaters (n = 154), in-line skaters (n = 190), and skateboarders (n = 254) aged 5 to 19 years who were hospitalized with injuries. Seventy-nine hospitals and pediatric trauma centers participating in the National Pediatric Trauma Registry between October 1988 and April 1997. Three quarters (75.8%) of the study sample were male, nearly half (47.8%) were injured on roads, and more than one third (37.1%) had head injuries. Among skateboarders, 50.8% had head injuries compared with 33.7% of in-line skaters and 18.8% of roller skaters (Pskateboarders were 8 times more likely to be severe or critical compared with roller skaters' injuries and more than 2 times as likely to be severe or critical compared with in-line skaters' injuries. Mean hospital length of stay was 6.0 days for skateboarders, 3.4 days for in-line skaters, and 2.4 days for roller skaters (PSkateboarders were more likely to be male and to be injured on roads than were in-line skaters or roller skaters. Skateboarding-related injuries are more severe and have more serious consequences than roller skating or in-line skating injuries. Research is needed to identify ergonomic and behavioral factors responsible for higher head injury risk to skateboarders, and interventions are needed to reduce the risk.

  14. Intrinsic cylindrical and spherical waves

    International Nuclear Information System (INIS)

    Ludlow, I K

    2008-01-01

    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

  15. Diffusion in a cylindrical plasma

    International Nuclear Information System (INIS)

    Reid, J.

    1977-04-01

    Modern plasma containment devices, such as the Tokamak, employ magnetic fields which are toroidal in shape. They are able to contain a plasma for times approaching a second. Magnetohydrodynamics (M.H.D.) is one of the most attractive theoretical methods for understanding their behaviour, but the equations involved are complex non-linear partial differential equations, and analytic methods are not available for their solution. Numerical methods must be used. A model system of equations representing a cylindrical plasma with no axial variation is considered. It is convenient to introduce a flux function psi for the component of the magnetic field directed around the axis of the cylinder, called the poloidal field, and the M.H.D. equations are rewritten in terms of psi. This produces a set of highly coupled equations describing the evolution of the flux function, the axial field and the plasma pressure. Various steps are taken to gain a better understanding of the properties of these equations. (author)

  16. Increasing the Energy Efficiency of the Cyclic Action Mechanisms in Rolling for a Roller Bed Used as an Example

    Science.gov (United States)

    andreev, A. N.; Kolesnichenko, D. A.

    2017-12-01

    The possibility of increasing the energy efficiency of the production cycle in a roller bed is briefly reviewed and justified. The sequence diagram of operation of the electrical drive in a roller bed is analyzed, and the possible increase in the energy efficiency is calculated. A method for energy saving is described for the application of a frequency-controlled asynchronous electrical drive of drive rollers in a roller bed with an increased capacitor capacity in a dc link. A fine mathematical model is developed to describe the behavior of the electrical drive during the deceleration of a roller bed. An experimental setup is created and computer simulation and physical modeling are performed. The basic information flows of the general hierarchical automatic control system of an enterprise are described and determined with allowance for the proposed method of increasing the energy efficiency.

  17. Simulation of accelerated strip cooling on the hot rolling mill run-out roller table

    Directory of Open Access Journals (Sweden)

    E.Makarov

    2016-07-01

    Full Text Available A mathematical model of the thermal state of the metal in the run-out roller table continuous wide hot strip mill. The mathematical model takes into account heat generation due to the polymorphic γ → α transformation of supercooled austenite phase state and the influence of the chemical composition of the steel on the physical properties of the metal. The model allows calculation of modes of accelerated cooling strips on run-out roller table continuous wide hot strip mill. Winding temperature calculation error does not exceed 20°C for 98.5 % of strips of low-carbon and low-alloy steels

  18. Verkkokaupan kansainvälistäminen Facebook-mainonnalla : Case HighRoller

    OpenAIRE

    Heikkinen, Tiia

    2016-01-01

    Verkkokauppa toimii HighRoller Suomi Oy:n HighRoller-lihashuoltolaiteen pääasiallisena myyntikanavana ja Facebook-markkinointikanavana. Tähän mennessä tuotetta on markkinoitu Facebookissa ilman varsinaista strategiaa. Nyt tuotetta viedään Ruotsiin ja uusia markkinoita varten suunniteltiin ja toteutettiin Facebook-mainoskampanja. Teoreettisessä viitekehyksessä käydään läpi aluksi digimarkkinointia, minkä jälkeen pohditaan sosiaalisen median merkitystä verkkokaupalle. Seuraavaksi keskitytää...

  19. Design, development and evaluation of a divergent roller sizer for almond kernels

    Directory of Open Access Journals (Sweden)

    D Ghanbarian

    2015-09-01

    Full Text Available Introduction: Iran is one of the major producers of almonds. According to the statistics released by FAO (2011, Iran with more than 110000 tons of almonds is the third in rank throughout the world. However, most Iranian almonds are presented as an unsorted and unpackaged product. Some producers sort their products by hand which is very time-consuming and labor-intensive. So, there is an essential need for suitable grading and packaging machines especially for the export of almond kernels.Grading, which is sometimes called sorting, is basically separating the material in different homogenous groups according to its specific characteristics like size, shape, color and on the basis of quality. Weighing is one of the best methods for grading agricultural products based on size, but due to its high cost and complexity of operations, usage of weigh size sorting machines is practically limited. So, sizing of most agricultural products is accomplished based on their dimensional attributes such as diameter, length, thickness or a combination of them. Field study shows that recently vibrating sizing machines are used for grading almond kernels. This type of sizing machine is huge, expensive, noisy and it consumes a lot of energy. Thus, the main objective of the present study was the design, development and evaluation of a new prototype of an almond kernel sizing machine. Materials and methods: It is important that the machine could resolve defects of existing vibrating machines. It should provide efficient and cost effective sizing for a wide range of kernel sizes and shapes. Furthermore, it should be of simple construction and be able to accept manual feeding. Previously conducted experiments showed that the thickness of the kernel is the most appropriate dimension for its sizing. Among the different types of dimensional sizing machines, the divergent roller grader which grades the products based on their thickness is considered to be one of the simplest

  20. Ion implantation planar in targets with semi-cylindrical grooves

    International Nuclear Information System (INIS)

    Filiz, Y.; Demokan, O.

    2002-01-01

    The experimental and numerical investigations suggest that the ion-matrix phase of the sheath evolution plays a crucial role in determining the ion flux to the target surfaces . It can easily be realized that conformal mapping of the target's surface by the sheath is questionable, or even inapplicable in the case of surfaces with fine irregularities or this continuities. The theoretical analysis of such cases is evidently quite complicated. On the other hand, most actual targets fall into this category, and hence, the understanding of the corresponding sheath behavior remains vital for accomplishing uniform implantation. The ion- matrix sheaths have been treated analytically by Conrad for planar, cylindrical and spherical targets successfully. Similar y, Sheridan and Zang et al. have investigated the ion matrix sheath in cylindrical bores, without and with axial electrodes, respectively. All these works assumed targets with infinite areas or length, Zeng et al. and Kwok et al. have started studying implantation into grooves, by carrying out simulations for the inner and outer races of bearings, which are modeled as semi- cylinders of infinite length. Finally, Demokan has presented the first analytic treatment of on matrix sheaths in two- dimensions, by considering targets with rectangular grooves of infinite length, representing a broad range of industrial items. In this work, ion-matrix sheath near infinite length are theoretically analysed. Understanding the sheath formation near such targets is essential for achieving successful ion implantation on the surfaces of a broad range of industrial products, including all types of bearings. The potential profiles both inside and outside the groove are derived and the consequent ion velocity higher plasma densities may improve the uniformity of implantation on the surfaces of such grooves. Furthermore, the sheath edge deformation due to the grooves, the variation of the angle of incidence on the surface of the groove

  1. Passive magnetic bearing configurations

    Science.gov (United States)

    Post, Richard F [Walnut Creek, CA

    2011-01-25

    A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.

  2. Cylindrical fabric-confined soil structures

    Science.gov (United States)

    Harrison, Richard A.

    A cylindrical fabric-soil structural concept for implementation on the moon and Mars which provides many advantages is proposed. The most efficient use of fabric is to fashion it into cylindrical tubes, creating cylindrical fabric-confined soil structures. The length, diameter, and curvature of the tubes will depend on the intended application. The cylindrical hoop forces provide radial confinement while end caps provide axial confinement. One of the ends is designed to allow passage of the soil into the fabric tube before sealing. Transportation requirements are reduced due to the low mass and volume of the fabric. Construction requirements are reduced due to the self-erection capability via the pneumatic exoskeleton. Maintenance requirements are reduced due to the passive nature of the concept. The structure's natural ductility is well suited for any seismic activity.

  3. Cylindrical-shaped nanotube field effect transistor

    KAUST Repository

    Hussain, Muhammad Mustafa

    2015-12-29

    A cylindrical-shaped nanotube FET may be manufactured on silicon (Si) substrates as a ring etched into a gate stack and filled with semiconductor material. An inner gate electrode couples to a region of the gate stack inside the inner circumference of the ring. An outer gate electrode couples to a region of the gate stack outside the outer circumference of the ring. The multi-gate cylindrical-shaped nanotube FET operates in volume inversion for ring widths below 15 nanometers. The cylindrical-shaped nanotube FET demonstrates better short channel effect (SCE) mitigation and higher performance (I.sub.on/I.sub.off) than conventional transistor devices. The cylindrical-shaped nanotube FET may also be manufactured with higher yields and cheaper costs than conventional transistors.

  4. Cylindrical-shaped nanotube field effect transistor

    KAUST Repository

    Hussain, Muhammad Mustafa; Fahad, Hossain M.; Smith, Casey E.; Rojas, Jhonathan Prieto

    2015-01-01

    A cylindrical-shaped nanotube FET may be manufactured on silicon (Si) substrates as a ring etched into a gate stack and filled with semiconductor material. An inner gate electrode couples to a region of the gate stack inside the inner circumference of the ring. An outer gate electrode couples to a region of the gate stack outside the outer circumference of the ring. The multi-gate cylindrical-shaped nanotube FET operates in volume inversion for ring widths below 15 nanometers. The cylindrical-shaped nanotube FET demonstrates better short channel effect (SCE) mitigation and higher performance (I.sub.on/I.sub.off) than conventional transistor devices. The cylindrical-shaped nanotube FET may also be manufactured with higher yields and cheaper costs than conventional transistors.

  5. Micromagnetic simulations of cylindrical magnetic nanowires

    KAUST Repository

    Ivanov, Yurii P.; Chubykalo-Fesenko, O.

    2015-01-01

    This chapter reviews micromagnetic simulations of cylindrical magnetic nanowires and their ordered arrays. It starts with a description of the theoretical background of micromagnetism. The chapter discusses main magnetization reversal modes, domain

  6. Plasma waves in an inhomogeneous cylindrical plasma

    International Nuclear Information System (INIS)

    Pesic, S.S.

    1976-01-01

    The complete dispersion equation governing small amplitude plasma waves propagating in an inhomogeneous cylindrical plasma confined by a helical magnetic field is solved numerically. The efficiency of the wave energy thermalization in the lower hybrid frequency range is studied

  7. Gravitational Instability of Cylindrical Viscoelastic Medium ...

    Indian Academy of Sciences (India)

    similar to that of viscoelastic fluid where both properties work together. They also ... cylindrical gravitational waves provides a strong motivation in this regard. .... which represents the solenoidal character of the magnetic field and the total stress.

  8. FRICTION TORQUE IN THE SLIDE BEARINGS

    Directory of Open Access Journals (Sweden)

    BONDARENKO L. N.

    2016-09-01

    Full Text Available Summary. Problem statement. Until now slide bearings are used widely in engineering. But the calculation is made on obsolete method that is based on undetermined parameters such as wear of the bearing shell. It is accepted in the literature that if the shaft and liner material are homogeneous, the workpiece surface are cylindrical as they wear and contact between them occurs at all points contact arc. Research objective. The purpose of this study is determine a friction torque in the slide bearings of power-basis parameters. Conclusions. Since the friction is primarily responsible for wear of cinematic pairs “pin – liner” and “pivot – liner” slide bearings. It is shown that the friction torquesof angles wrap, that are obtained by the formulas and given in literature, are not only qualitatively but also quantitatively, namely, the calculation by literature to the formulas the friction torques are proportional to the angle wrap and the calculation by improved formulas the friction torques are inversely proportional to the angle wrap due to the reduction the normal pressure. Underreporting friction torque at large angle wrap is between 40 and 15 %. The difference in the magnitude of friction torque in the run-in and run-out cinematic pairs with real method of machining is 2...3 %, which it is possible to declare of reducing the finish of contacting surface of slide bearings.

  9. Radon progeny distribution in cylindrical diffusion chambers

    International Nuclear Information System (INIS)

    Pressyanov, Dobromir S.

    2008-01-01

    An algorithm to model the diffusion of radioactive decay chain atoms is presented. Exact mathematical solutions in cylindrical geometry are given. They are used to obtain expressions for the concentrations of 222 Rn progeny atoms in the volume and deposited on the wall surface in cylindrical diffusion chambers. The dependence of volume fractions of 222 Rn progeny and chamber sensitivity on the coefficient of diffusion of 222 Rn progeny atoms in air is modeled.

  10. Cylindrical geometry for proportional and drift chambers

    International Nuclear Information System (INIS)

    Sadoulet, B.

    1975-06-01

    For experiments performed around storage rings such as e + e - rings or the ISR pp rings, cylindrical wire chambers are very attractive. They surround the beam pipe completely without any dead region in the azimuth, and fit well with the geometry of events where particles are more or less spherically produced. Unfortunately, cylindrical proportional or drift chambers are difficult to make. Problems are discussed and two approaches to fabricating the cathodes are discussed. (WHK)

  11. Cylindrical dust acoustic waves with transverse perturbation

    International Nuclear Information System (INIS)

    Xue Jukui

    2003-01-01

    The nonlinear dust acoustic waves in dusty plasmas with the combined effects of bounded cylindrical geometry and the transverse perturbation are studied. Using the perturbation method, a cylindrical Kadomtsev-Petviashvili (CKP) equation that describes the dust acoustic waves is deduced for the first time. A particular solution of this CKP equation is also obtained. It is shown that the dust acoustic solitary waves can exist in the CKP equation

  12. The Pulsed Cylindrical Magnetron for Deposition

    Science.gov (United States)

    Korenev, Sergey

    2012-10-01

    The magnetron sputtering deposition of films and coatings broadly uses in microelectronics, material science, environmental applications and etc. The rate of target evaporation and time for deposition of films and coatings depends on magnetic field. These parameters link with efficiency of gas molecules ionization by electrons. The cylindrical magnetrons use for deposition of films and coatings on inside of pipes for different protective films and coatings in oil, chemical, environmental applications. The classical forming of magnetic field by permanent magnets or coils for big and long cylindrical magnetrons is complicated. The new concept of pulsed cylindrical magnetron for high rate deposition of films and coating for big and long pipes is presented in this paper. The proposed cylindrical magnetron has azimuthally pulsed high magnetic field, which allows forming the high ionized plasma and receiving high rate of evaporation material of target (central electrode). The structure of proposed pulsed cylindrical magnetron sputtering system is given. The main requirements to deposition system are presented. The preliminary data for forming of plasma and deposition of Ta films and coatings on the metal pipers are discussed. The comparison of classical and proposed cylindrical magnetrons is given. The analysis of potential applications is considered.

  13. Visualizing asphalt roller trajectories in context: acquiring, processing, and representing sensor readings

    NARCIS (Netherlands)

    Vasenev, Alexandr

    2015-01-01

    The asphalt compaction process relies heavily on the skills and knowledge of roller operators who act alongside other stakeholders involved in asphalt paving. It is essential that these construction specialists: (1) are adequately informed about the initial temperature distribution of the asphalt

  14. The two-dimensional cutting stock problem within the roller blind production process

    NARCIS (Netherlands)

    E.R. de Gelder; A.P.M. Wagelmans (Albert)

    2007-01-01

    textabstractIn this paper we consider a two-dimensional cutting stock problem encountered at a large manufacturer of window covering products. The problem occurs in the production process of made-to-measure roller blinds. We develop a solution method that takes into account the characteristics of

  15. Daylighting performance evaluation of a bottom-up motorized roller shade

    Energy Technology Data Exchange (ETDEWEB)

    Kapsis, K.; Athienitis, A.K.; Zmeureanu, R.G. [Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, QC (Canada); Tzempelikos, A. [School of Civil Engineering, Purdue University, West Lafayette, IN (United States)

    2010-12-15

    This paper presents an experimental and simulation study for quantifying the daylighting performance of bottom-up roller shades installed in office spaces. The bottom-up shade is a motorized roller shade that opens from top to bottom operating in the opposite direction of a conventional roller shade, so as to cover the bottom part of the window, while allowing daylight to enter from the top part of the window, reaching deeper into the room. A daylighting simulation model, validated with full-scale experiments, was developed in order to establish correlations between the shade position, outdoor illuminance and work plane illuminance for different outdoor conditions. Then, a shading control algorithm was developed for application in any location and orientation. The validated model was employed for a sensitivity analysis of the impact of shade optical properties and control on the potential energy savings due to the use of daylighting. The results showed that Daylight Autonomy for the bottom-up shade is 8-58% higher compared to a conventional roller shade, with a difference of 46% further away from the facade, where the use of electric lighting is needed most of the time. The potential reduction in energy consumption for lighting is 21-41%. (author)

  16. Preliminary evaluation of steel-roller round baler for woody biomass baling

    Science.gov (United States)

    B. J. Stokes; D. L. Sirois; S. L. Woodfin

    1987-01-01

    A round hay baler with little modification was used to bale small-diameter, crushed trees. The trees had been crushed using a series of compression rollers. Bale cores had to be developed by hand before the baler became self-feeding. Windrowed material was packed off the ground by the baler system after a core had been developed.

  17. Liikluseksperimendis edestas roller tsiklit ja teisi osalejaid : “2 vs 4″

    Index Scriptorium Estoniae

    2010-01-01

    12. mail toimus Tallinnas keskkonnasõbraliku motonäituse MoMa raames eksperiment, milles osalesid jalgratas, elektriroller, roller, mootorratas ja auto. Marsruudil Miidurand-Nõmme üritati hommikuses liikluses välja selgitada, milline neist sõiduvahendest kõige edukamalt toime tuleb

  18. Modelling and simulation of dynamic wheel-rail interaction using a roller rig

    International Nuclear Information System (INIS)

    Anyakwo, A; Pislaru, C; Ball, A; Gu, F

    2012-01-01

    The interaction between the wheel and rail greatly influences the dynamic response of railway vehicles on the track. A roller rig facility can be used to study and monitor real time parameters that influence wheel-rail interaction such as wear, adhesion, friction and corrugation without actual field tests being carried out. This paper presents the development of the mathematical models for full scale roller rig and 1/5 scale roller rig and the wear prediction model based on KTH wear function. The simulated critical speed for the 1/5 scale roller rig is about one-fifth of the critical speed for the full scale model so the simulated results compare well with the theory related to wheel-rail contact and dynamics. Also the differences between the simulated rolling radii for the full scale model with and without wear function are analysed. This paper presents the initial stage of a large scale research project where the influence of wear on the wheel-rail performance will be studied in more depth.

  19. Out-of-plane stability of roller bent steel arches – an experimental investigation

    NARCIS (Netherlands)

    La Poutre, D.B.; Spoorenberg, R.C.; Snijder, H.H.; Hoenderkamp, J.C.D.

    2013-01-01

    This paper presents an experimental investigation of the elastic-plastic out-of-plane buckling response of roller bent circular steel arches subjected to a single force applied to the crown. The experiments are used to validate a finite element model described in a related paper. A series of 15

  20. Acceleration in One, Two, and Three Dimensions in Launched Roller Coasters

    Science.gov (United States)

    Pendrill, Ann-Marie

    2008-01-01

    During a roller coaster ride, the body experiences acceleration in three dimensions. An accelerometer can measure and provide a graph of the forces on the body during different parts of a ride. To couple the experience of the body to pictures of the ride and an analysis of data can contribute to a deeper understanding of Newton's laws. This…

  1. Roller-massager application to the quadriceps and knee-joint range of motion and neuromuscular efficiency during a lunge.

    Science.gov (United States)

    Bradbury-Squires, David J; Noftall, Jennifer C; Sullivan, Kathleen M; Behm, David G; Power, Kevin E; Button, Duane C

    2015-02-01

    Roller massagers are used as a recovery and rehabilitative tool to initiate muscle relaxation and improve range of motion (ROM) and muscular performance. However, research demonstrating such effects is lacking. To determine the effects of applying a roller massager for 20 and 60 seconds on knee-joint ROM and dynamic muscular performance. Randomized controlled clinical trial. University laboratory. Ten recreationally active men (age = 26.6 ± 5.2 years, height = 175.3 ± 4.3 cm, mass = 84.4 ± 8.8 kg). Participants performed 3 randomized experimental conditions separated by 24 to 48 hours. In condition 1 (5 repetitions of 20 seconds) and condition 2 (5 repetitions of 60 seconds), they applied a roller massager to the quadriceps muscles. Condition 3 served as a control condition in which participants sat quietly. Visual analog pain scale, electromyography (EMG) of the vastus lateralis (VL) and biceps femoris during roller massage and lunge, and knee-joint ROM. We found no differences in pain between the 20-second and 60-second roller-massager conditions. During 60 seconds of roller massage, pain was 13.5% (5.7 ± 0.70) and 20.6% (6.2 ± 0.70) greater at 40 seconds and 60 seconds, respectively, than at 20 seconds (P joint ROM was 10% and 16% greater in the 20-second and 60-second roller-massager conditions, respectively, than the control condition (P joint ROM and neuromuscular efficiency during a lunge.

  2. Temperature and Thermal Expansion Analysis of the Cooling Roller Based on the Variable Heat Flux Boundary Condition

    Science.gov (United States)

    Li, Yongkang; Yang, Yang; He, Changyan

    2018-06-01

    Planar flow casting (PFC) is a primary method for preparing an amorphous ribbon. The qualities of the amorphous ribbon are significantly influenced by the temperature and thermal expansion of the cooling roller. This study proposes a new approach to analyze the three-dimensional temperature and thermal expansion of the cooling roller using variable heat flux that acted on the cooling roller as a boundary condition. First, a simplified two-dimensional model of the PFC is developed to simulate the distribution of the heat flux in the circumferential direction with the software FLUENT. The resulting heat flux is extended to be three-dimensional in the ribbon's width direction. Then, the extended heat flux is imported as the boundary condition by the CFX Expression Language, and the transient temperature of the cooling roller is analyzed in the CFX software. Next, the transient thermal expansion of the cooling roller is simulated through the thermal-structural coupling method. Simulation results show that the roller's temperature and expansion are unevenly distributed, reach the peak value in the middle width direction, and the quasi-steady state of the maximum temperature and thermal expansion are achieved after approximately 50 s and 150 s of casting, respectively. The minimum values of the temperature and expansion are achieved when the roller has a thickness of 45 mm. Finally, the reliability of the approach proposed is verified by measuring the roller's thermal expansion on the spot. This study provides theoretical guidance for the roller's thermal expansion prediction and the gap adjustment in the PFC.

  3. Knee joint position sense of roller hockey players: a comparative study.

    Science.gov (United States)

    Venâncio, João; Lopes, Diogo; Lourenço, Joaquim; Ribeiro, Fernando

    2016-06-01

    This study aimed to compare knee joint position sense of roller hockey players with an age-matched group of non-athletes. Forty-three male participants voluntarily participated in this cross-sectional study: 21 roller hockey players (mean age: 23.2 ± 4.2 years old, mean weight: 81.8 ± 9.8 kg, mean height: 180.5 ± 4.1 cm) and 22 age-matched non-athletes (mean age: 23.7 ± 3.9 years old, mean weight: 85.0 ± 6.2 kg, mean height: 181.5 ± 5.0 cm). Knee joint position sense of the dominant limb was evaluated using a technique of open-kinetic chain and active knee positioning. Joint position sense was reported using absolute, relative and variable angular errors. The main results indicated that the group of roller hockey players showed significantly lower absolute (2.4 ± 1.2º vs. 6.5 ± 3.2º, p ≤ 0.001) and relative (1.7 ± 2.1º vs. 5.8 ± 4.4º, p ≤ 0.001) angular errors in comparison with the non-athletes group. In conclusion, the results from this present study suggest that proprioceptive acuity, assessed by measuring joint position sense, is increased in roller hockey players. The enhanced proprioception of the roller hockey players could contribute to injury prevention and improved performance during sporting activities.

  4. DETERMINATION OF ADHESIVE STRENGTH LAYER’S ROLLER COMPACTED CONCRETE THE METHOD AXIAL EXTENSION

    Directory of Open Access Journals (Sweden)

    Tang Van Lam

    2017-07-01

    Full Text Available Roller compacted concrete for the construction of hydraulic and hydroelectric buildings is a composite material, which consists of a binder, fine aggregate (sand, coarse aggregate (gravel or crushed stone, water and special additives that provide the desired concrete workability and impart the required concrete performance properties. Concrete mixture is prepared at from concrete mixing plants strictly metered quantities of cement, water, additives and graded aggregates, whereupon they are delivered to the site laying Mixer Truck and sealing layers with each stack layer. The advantages of roller compaction technology should include the reduction of construction time, which allows fast commissioning construction projects, as well as reduce the amount of investment required. One of the main problems encountered in the process of roller compaction of the concrete mix is the need to provide the required adhesion strength between layers of concrete. This paper presents a method for determining the strength of adhesion between the concrete layers of different ages roller compacted concrete using axial tension. This method makes it possible to obtain objective and accurate results with a total thickness of layers of compacted concrete of up to 300…400 mm. Results from this method, studies have shown that the value of strength between the concrete layers in addition to the composition of the concrete and adhesion depends on the quality and the parallel end surfaces of the cylinder-models, which are mounted steel plates for axial tension, as well as the state of the contact surfaces of the concrete layer. The method can be used to determine the strength of interlayer adhesion in roller compacted concrete, which are used in the construction of dams and other hydraulic structures.

  5. An Evershed type superconducting flywheel bearing

    Energy Technology Data Exchange (ETDEWEB)

    Cansiz, A.; Campbell, A.M.; Coombs, T.A

    2003-07-15

    The objective of this work is to develop a bearing using high temperature superconductors (HTSs) for use in an energy storage flywheel. The experimental apparatus includes a cylindrical rotor levitated with the Evershed design in which the majority of the levitation force is provided by a permanent magnet arrangement and the stabilization of the system is achieved by HTS elements. The design characteristics and dynamics of the bearing associated with the rotor part are presented. The instrumentation measures the out of balance force and magnetomechanical stiffness associated with the rotor. A study of the rotational losses was performed using free spin down experiments associated with magnetic field variation measurements. The results are consistent with the loss being caused by hysteresis in the superconductor due to magnet inhomogeneity.

  6. Recalibrated Equations for Determining Effect of Oil Filtration on Rolling Bearing Life

    Science.gov (United States)

    Needelman, William M.; Zaretsky, Erwin V.

    2014-01-01

    In 1991, Needelman and Zaretsky presented a set of empirically derived equations for bearing fatigue life (adjustment) factors (LFs) as a function of oil filter ratings. These equations for life factors were incorporated into the reference book, "STLE Life Factors for Rolling Bearings." These equations were normalized (LF = 1) to a 10-micrometer filter rating at Beta(sub x) = 200 (normal cleanliness) as it was then defined. Over the past 20 years, these life factors based on oil filtration have been used in conjunction with ANSI/ABMA standards and bearing computer codes to predict rolling bearing life. Also, additional experimental studies have been made by other investigators into the relationship between rolling bearing life and the size, number, and type of particle contamination. During this time period filter ratings have also been revised and improved, and they now use particle counting calibrated to a new National Institute of Standards and Technology (NIST) reference material, NIST SRM 2806, 1997. This paper reviews the relevant bearing life studies and describes the new filter ratings. New filter ratings, Beta(sub x(c)) = 200 and Beta(sub x(c)) = 1000, are benchmarked to old filter ratings, Beta(sub x) = 200, and vice versa. Two separate sets of filter LF values were derived based on the new filter ratings for roller bearings and ball bearings, respectively. Filter LFs can be calculated for the new filter ratings.

  7. SHABERTH - ANALYSIS OF A SHAFT BEARING SYSTEM (CRAY VERSION)

    Science.gov (United States)

    Coe, H. H.

    1994-01-01

    The SHABERTH computer program was developed to predict operating characteristics of bearings in a multibearing load support system. Lubricated and non-lubricated bearings can be modeled. SHABERTH calculates the loads, torques, temperatures, and fatigue life for ball and/or roller bearings on a single shaft. The program also allows for an analysis of the system reaction to the termination of lubricant supply to the bearings and other lubricated mechanical elements. SHABERTH has proven to be a valuable tool in the design and analysis of shaft bearing systems. The SHABERTH program is structured with four nested calculation schemes. The thermal scheme performs steady state and transient temperature calculations which predict system temperatures for a given operating state. The bearing dimensional equilibrium scheme uses the bearing temperatures, predicted by the temperature mapping subprograms, and the rolling element raceway load distribution, predicted by the bearing subprogram, to calculate bearing diametral clearance for a given operating state. The shaft-bearing system load equilibrium scheme calculates bearing inner ring positions relative to the respective outer rings such that the external loading applied to the shaft is brought into equilibrium by the rolling element loads which develop at each bearing inner ring for a given operating state. The bearing rolling element and cage load equilibrium scheme calculates the rolling element and cage equilibrium positions and rotational speeds based on the relative inner-outer ring positions, inertia effects, and friction conditions. The ball bearing subprograms in the current SHABERTH program have several model enhancements over similar programs. These enhancements include an elastohydrodynamic (EHD) film thickness model that accounts for thermal heating in the contact area and lubricant film starvation; a new model for traction combined with an asperity load sharing model; a model for the hydrodynamic rolling and

  8. On the bi-dimensional variational decomposition applied to nonstationary vibration signals for rolling bearing crack detection in coal cutters

    International Nuclear Information System (INIS)

    Jiang, Yu; Li, Zhixiong; Zhang, Chao; Peng, Z; Hu, Chao

    2016-01-01

    This work aims to detect rolling bearing cracks using a variational approach. An original method that appropriately incorporates bi-dimensional variational mode decomposition (BVMD) into discriminant diffusion maps (DDM) is proposed to analyze the nonstationary vibration signals recorded from the cracked rolling bearings in coal cutters. The advantage of this variational decomposition based diffusion map (VDDM) method in comparison to the current DDM is that the intrinsic vibration mode of the crack can be filtered into a limited bandwidth in the frequency domain with an estimated central frequency, thus discarding the interference signal components in the vibration signals and significantly improving the crack detection performance. In addition, the VDDM is able to simultaneously process two-channel sensor signals to reduce information leakage. Experimental validation using rolling bearing crack vibration signals demonstrates that the VDDM separated the raw signals into four intrinsic modes, including one roller vibration mode, one roller cage vibration mode, one inner race vibration mode, and one outer race vibration mode. Hence, reliable fault features were extracted from the outer race vibration mode, and satisfactory crack identification performance was achieved. The comparison between the proposed VDDM and existing approaches indicated that the VDDM method was more efficient and reliable for crack detection in coal cutter rolling bearings. As an effective catalyst for rolling bearing crack detection, this newly proposed method is useful for practical applications. (paper)

  9. Teddy Bear Stories

    DEFF Research Database (Denmark)

    van Leeuwen, Theo; Caldas-Coulthardt, Carmen

    2014-01-01

    This paper presents a semiotic analysis of a key cultural artefact, the teddy bear. After introducing the iconography of the teddy bear, it analyses different kinds of stories to show how teddy bears are endowed with meaning in everyday life: stories from children's books, reminiscenses by adults...... bears have traditionally centred on interpersonal relations within the nuclear family, but have recently been institutionalized and commercialized....

  10. 75 FR 41148 - Tapered Roller Bearings and Parts Thereof, Finished or Unfinished, From the People's Republic of...

    Science.gov (United States)

    2010-07-15

    ...: Certain Preserved Mushrooms From the People's Republic of China, 66 FR 31204 (June 11, 2001), and... applicable to the relevant month of the data being downloaded and converted.\\40\\ \\39\\ See Certain Preserved Mushrooms from the People's Republic of China: Preliminary Results of Antidumping Duty New Shipper Review...

  11. 78 FR 12035 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the People's Republic of...

    Science.gov (United States)

    2013-02-21

    ... investigated or reviewed PRC and non-PRC exporters not listed above that have separate rates, the cash deposit... cash deposit rate will be the PRC- wide rate of 92.84 percent; and (4) for all non-PRC exporters of... expenses twice for certain sales. We unintentionally failed to offset CPZ/SKF's freight expenses with its...

  12. 77 FR 32522 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the People's Republic of...

    Science.gov (United States)

    2012-06-01

    ... is renumbered as 8708.99.8180; see Id. Bona Fides Sale Analysis For this review, consistent with the... POR. In evaluating whether or not a sale in a new shipper review is commercially reasonable, and... Shipper Review, 67 FR 11283 (March 13, 2002)). The Department preliminarily finds that the sales of...

  13. 77 FR 65668 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished From the People's Republic of...

    Science.gov (United States)

    2012-10-30

    ... Comment 3. We have recalculated surrogate financial ratios using different financial statements from those... valorem antidumping duty assessment rates based on the ratio of the total amount of dumping calculated for...

  14. 78 FR 3396 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the People's Republic of...

    Science.gov (United States)

    2013-01-16

    ... Comment 2: Financial Ratios Comment 3: Surrogate Value for Labor Comment 4: Surrogate Value and Labor... Electronic Co., Ltd. (``Zhejiang Zhaofeng''). We invited interested parties to comment on our Preliminary Results and post-preliminary analysis. Based on our analysis of the comments received, we made certain...

  15. 76 FR 3086 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the People's Republic of...

    Science.gov (United States)

    2011-01-19

    ...: Adjustments to Financial Ratio Comment 17: Wages [FR Doc. 2011-1026 Filed 1-18-11; 8:45 am] BILLING CODE 3510.... (``New Torch''). We invited interested parties to comment on our Preliminary Results. Based on our analysis of the comments received, we made certain changes to our margin calculations for PBCD, SKF, and...

  16. 77 FR 40579 - Tapered Roller Bearings and Parts Thereof, Finished or Unfinished, From the People's Republic of...

    Science.gov (United States)

    2012-07-10

    ... authority to negotiate and sign contracts and other agreements; (3) whether the company has autonomy from... other agreements; and (4) it has autonomy from the government regarding the selection of management.\\29... regarding energy reporting in financial statements. In the instant review, CPZ/SKF reported sales that were...

  17. 76 FR 41207 - Tapered Roller Bearings and Parts Thereof, Finished or Unfinished, From the People's Republic of...

    Science.gov (United States)

    2011-07-13

    ...) whether the respondent has autonomy from the government in making decisions regarding the selection of... respondent has autonomy from the government regarding the selection of management.\\28\\ \\28\\ See Sihe's SRA... published in the International Monetary Fund's International Financial Statistics.\\38\\ \\37\\ See Surrogate...

  18. 75 FR 844 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, from the People's Republic of...

    Science.gov (United States)

    2010-01-06

    ... Parts Thereof, Finished and Unfinished, from the People's Republic of China: Final Results of the 2007... Republic of China: Preliminary Results of the 2007-2008 Administrative Review of the Antidumping Duty Order..., through May 31, 2008. The administrative [[Page 845

  19. 77 FR 2271 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the People's Republic of...

    Science.gov (United States)

    2012-01-17

    ... HTSUS item numbers are provided for convenience and customs purposes, the written description of the... and TRBs,'' dated February 7, 2011. On April 18, 2011, in response to an inquiry from New Trend Engineering Limited (``New Trend''), the Department ruled that: (1) New Trend's splined and non-splined wheel...

  20. 77 FR 52682 - Tapered Roller Bearings and Parts Thereof, Finished and Unfinished, From the People's Republic of...

    Science.gov (United States)

    2012-08-30

    ....80.80.\\5\\ Although the HTSUS item numbers are provided for convenience and customs purposes, the... Trend Engineering Ltd.'s Wheel Hub Assemblies,'' dated April 18, 2011 (finding New Trend Engineering...

  1. Acute, fatal Sarcocystis calchasi-associated hepatitis in Roller pigeons (Columbia livia f. dom.) at Philadelphia Zoo

    Science.gov (United States)

    Four Roller pigeons (Columba livia f. dom.) at the Philadelphia Zoo died suddenly. Necropsy examination revealed macroscopic hepatitis. Microscopically, the predominant lesions were in liver, characterized with necrosis and mixed cell inflammatory response. Sarcocystis calchasi-like schizonts and fr...

  2. Marine aggregates and transparent exopolymeric particles (TEPs) as substrates for the stramenopilan fungi, the thraustochytrids: Roller table experimental approach.

    Digital Repository Service at National Institute of Oceanography (India)

    Damare, V.S.; Raghukumar, S.

    In order to understand the kind of organic substrates utilized by thraustochytrids in the coastal water column, their growth in the presence of Transparent Exopolymeric Substances (TEPS) and aggregates generated in roller table experiments...

  3. Long-Life, Oil-Free Polymeric, Multi-Roller Traction Drives for Planetary Vehicle Surface Exploration, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Multi-roller traction drives have several advantages relative to geared units for aerospace and commercial drive applications. Among these are zero backlash, low...

  4. Forced vibrations of rotating circular cylindrical shells

    International Nuclear Information System (INIS)

    Igawa, Hirotaka; Maruyama, Yoshiyuki; Endo, Mitsuru

    1995-01-01

    Forced vibrations of rotating circular cylindrical shells are investigated. Basic equations, including the effect of initial stress due to rotation, are formulated by the finite-element method. The characteristic relations for finite elements are derived from the energy principle by considering the finite strain. The equations of motion can be separated into quasi-static and dynamic ones, i.e., the equations in the steady rotating state and those in the vibration state. Radial concentrated impulses are considered as the external dynamic force. The transient responses of circular cylindrical shells are numerically calculated under various boundary conditions and rotating speeds. (author)

  5. Tearing instability in cylindrical plasma configuration

    International Nuclear Information System (INIS)

    Zelenyj, L.M.

    1979-01-01

    The effect of the neutral-layer cylindrical geometry on the development of the tearing instability has been investigated in detail. The increments of the instability for all the regimes have been found. The influence of cylindrical effects becomes manifesting itself at small, as compared to the layer characteristic thickness, distances from the axis, and, finally, the electron regime of the instability development transforms into an ion one. The results obtained are of interest for studying the plasma stability in the devices of the ''Astron'' type and in magnetospheres of cosmic objects

  6. Scattering of spermatozoa off cylindrical pillars

    Science.gov (United States)

    Bukatin, Anton; Lushi, Enkeleida; Kantsler, Vasily

    2017-11-01

    The motion of micro-swimmers in structured environments, even though crucial in processes such as in vivo and in vitro egg fertilization, is still not completely understood. We combine microfluidic experiments with mathematical modeling of 3D swimming near convex surfaces to quantify the dynamics of individual sperm cells in the proximity of cylindrical pillars. Our results show that the hydrodynamic and contact forces that account for the shape asymmetry and flagellar motion, are crucial in correctly describing the dynamics observed in the experiments. Last, we discuss how the size of the cylindrical obstacles determines whether the swimmers scatter off or get trapped circling the pillar.

  7. Micromagnetic simulations of cylindrical magnetic nanowires

    KAUST Repository

    Ivanov, Yurii P.

    2015-05-27

    This chapter reviews micromagnetic simulations of cylindrical magnetic nanowires and their ordered arrays. It starts with a description of the theoretical background of micromagnetism. The chapter discusses main magnetization reversal modes, domain wall types, and state diagrams in cylindrical nanowires of different types and sizes. The results of the hysteresis process in individual nanowires and nanowire arrays also are presented. Modeling results are compared with experimental ones. The chapter also discusses future trends in nanowire applications in relation to simulations, such as current-driven dynamics, spintronics, and spincaloritronics. The main micromagnetic programs are presented and discussed, together with the corresponding links.

  8. Cylindrical concave body of composite fibrous material

    International Nuclear Information System (INIS)

    1979-01-01

    The invention is concerned with a cylindrical concave body of compound fibrous material which is intended to be exposed to high rotation speeds around its own longitudinal axis. The concave body in question has at least one layer of fibrils that are interwoven and enclose an identical angle with the longitudinal axis of the concave body in both directions. The concave body in question also has at least a second layer of fibrils that run in the direction of the circumference and are fitted radially to the outside. The cylindrical concave body of the invention is particularly well suited for application as a rotor tube in a gas ultra-centrifuge

  9. Cylindrical pressure vessel constructed of several layers

    International Nuclear Information System (INIS)

    Yamauchi, Takeshi.

    1976-01-01

    For a cylindrical pressure vessel constructed of several layers whose jacket has at least one circumferential weld joining the individual layers, it is proposed to provide this at least at the first bending line turning point (counting from the weld between the jacket and vessel floor), which the sinusoidally shaped jacket has. The section of the jacket extending in between should be made as a full wall section. The proposal is based on calculations of the bending stiffness of cylindrical jackets, which could not yet be confirmed for jackets having several layers. (UWI) [de

  10. Magnetic guns with cylindrical permanent magnets

    DEFF Research Database (Denmark)

    Vokoun, David; Beleggia, Marco; Heller, Luděk

    2012-01-01

    The motion of a cylindrical permanent magnet (projectile) inside a tubular permanent magnet, with both magnets magnetized axially, illustrates nicely the physical principles behind the operation of magnetic guns. The force acting upon the projectile is expressed semi-analytically as derivative...... of the magnetostatic interaction energy. For comparison, the forces involved are also calculated numerically using finite elements methods. Based on the conservation of the magnetostatic and kinetic energies, the exit and asymptotic velocities are determined. The derived formulas can be used to optimize the generated...... forces and motion of the inner cylindrical magnet....

  11. Application research of ferrous matrix composites in roller ring used in high-speed wire/bar rolling mill

    International Nuclear Information System (INIS)

    Song Yanpei; Li Xiuqing; Bi Shuangxu

    2010-01-01

    Research highlights: → A composite structure roller rings was fabricated by centrifugal casting. → The roller rings consisted of outer WCP/Fe-C composites layer and inner Fe-C alloy matrix. → Hardness attained to HRA80-85 in the composites layer, and HRA73-76 in inner Fe-C alloy matrix where the toughness was over 8 J/cm 2 . → The wear resistance of the roller rings excelled that of high-speed steel, and approached to that of the WC hard alloy roll. → The production cost of the WCP/Fe-C composites roller ring decreased by 50%. - Abstract: Tungsten carbide particle (WC P ) reinforced ferrous matrix composites roller rings were fabricated by centrifugal casting. The microstructures, properties and application effect of the composites roller rings were investigated by SEM, TEM and various property testers. The experimental results show that the WC P were uniformly distributed in outer reinforced-layer (working-layer) of 20-50 mm in thickness and their volume fraction reached 60-80 vol.%; there was a good interface bonding between WC P and Fe-C alloy without any reaction products; hardness attained to HRA80-85 in working-layer, and HRA73-76 in inner ferrous matrix where the toughness was over 8 J/cm 2 ; the wear resistance of the composites roller rings excels that of high-speed steel; service life of the composites parts approached to that of the WC hard alloy roll when the same WC P -volume-fraction in working-layer were obtained for both of them, but the production cost of the WC P /Fe-C composites roller ring decreased by 50%.

  12. Effect of Using Porcelanite as Partial Replacement of Fine Aggregate on Roller Compacted Concrete with Different Curing Methods

    Directory of Open Access Journals (Sweden)

    Abeer Abdulqader Salih

    2016-09-01

    Full Text Available Roller-Compacted Concrete is a no-slump concrete, with no reinforcing steel, no forms, no finishing and wet enough to support compaction by vibratory rollers. Due to the effect of curing on properties and durability of concrete, the main purpose of this research is to study the effect of various curing methods (air curing, 7 days water curing, and permanent water curing and porcelanite (local material used as an Internal Curing agent with different replacement percentages of fine aggregate (volumetric replacement on some properties of Roller-Compacted Concrete and to explore the possibility of introducing practical Roller-Compacted Concrete for road pavement with minimum requirement of curing. Specimens were sawed from slabs of (380*380*100 mm for determination of Ultrasonic Pulse Velocity (UPV and Voids volume. Results show that using (5 % porcelanite improved the results of UPV and Voids volume of Roller-Compacted Concrete (with air curing as compared with reference Roller-Compacted Concrete (with permanent water curing by percentages ranging from(3.6 to 28.9% and (-8 to -15.5% respectively.

  13. Pervasive liquid metal based direct writing electronics with roller-ball pen

    Directory of Open Access Journals (Sweden)

    Yi Zheng

    2013-11-01

    Full Text Available A roller-ball pen enabled direct writing electronics via room temperature liquid metal ink was proposed. With the rolling to print mechanism, the metallic inks were smoothly written on flexible polymer substrate to form conductive tracks and electronic devices. The contact angle analyzer and scanning electron microscope were implemented to disclose several unique inner properties of the obtained electronics. An ever high writing resolution with line width and thickness as 200 μm and 80 μm, respectively was realized. Further, with the administration of external writing pressure, GaIn24.5 droplets embody increasing wettability on polymer which demonstrates the pervasive adaptability of the roller-ball pen electronics.

  14. Experimental performance investigation of glazing system combined with internal roller blinds

    DEFF Research Database (Denmark)

    Larsen, Olena Kalyanova; Jensen, Rasmus Lund; Iversen, Tore Dahl

    2016-01-01

    Modern low-energy buildings are often associated with efficient shading devices, as an inevitable component to reduce the peak heat gain in the building and to improve visual comfort. Internal shading devices may have inferior performance compared to external shading, but these are still the most...... used in practice due to lower cost, simplicity and better acceptance between architects and users. The interplay between glazing systems and internal shading devices has been studied and in everyday practice this interplay is described by the solar shading coefficient and the total g......-value of the system (window + roller blind). Solar shading coefficient in such practice is assumed to be independent of the window properties and solar incidence angle. This paper is aimed to illustrate the deviation between the actual and assumed performance of the window system with internal roller blind. This task...

  15. Granule fraction inhomogeneity of calcium carbonate/sorbitol in roller compacted granules

    DEFF Research Database (Denmark)

    Bacher, Charlotte; Olsen, P.M.; Bertelsen, P.

    2008-01-01

    The granule fraction inhomogeneity of roller compacted granules was examined on mixtures of three different morphologic forms of calcium carbonate and three particle sizes of sorbitol. The granule fraction inhomogeneity was determined by the distribution of the calcium carbonate in each of the 10...... size fractions between 0 and 2000 µm and by calculating the demixing potential. Significant inhomogeneous occurrence of calcium carbonate in the size fractions was demonstrated, depending mostly on the particles sizes of sorbitol but also on the morphological forms of calcium carbonate......, the ability of the powder to agglomerate in the roller compactor was demonstrated to be related to the ability of the powder to be compacted into a tablet, thus the most compactable calcium carbonate and the smallest sized sorbitol improved the homogeneity by decreasing the demixing potential....

  16. Study on the Effect of Steel Wheel and Ground on Single Steel Vibratory Roller

    Science.gov (United States)

    Li, Jiabo; You, Guanghui; Qiao, Jiabin; Ye, Min; Guo, Jin; Zhang, Hongyang

    2018-03-01

    In the compacting operation of single drum vibratory roller, the forces acting on the foundation of drum include the weight of the drum, the weight of the frame, the exciting force and so on. Based on the theoretical study of ground mechanics, this paper analyzes and calculates the forces acting on the steel wheel and the ground, and obtains the distribution of the laminar stress in the ground when the working plane vibrates. Derive the formula of dynamic compressive stress and static compressive stress in the foundation during vibration compaction. Through the compaction test of the soil trough of 20T single drum roller, the compressive stress data of the soil hydraulic field are obtained. The data of the dynamic compressive stress and the static compressive stress of each layer during the third compaction are obtained, and the theoretical research is verified.

  17. A roller-like bird (Coracii) from the Early Eocene of Denmark.

    Science.gov (United States)

    Bourdon, Estelle; Kristoffersen, Anette V; Bonde, Niels

    2016-09-27

    The fossil record of crown group birds (Neornithes) prior to the Cretaceous-Paleogene boundary is scarce and fragmentary. Early Cenozoic bird fossils are more abundant, but are typically disarticulated and/or flattened. Here we report the oldest roller (Coracii), Septencoracias morsensis gen. et sp. nov. (Primobucconidae), based on a new specimen from the Early Eocene (about 54 million years ago) Fur Formation of Denmark. The new fossil is a nearly complete, three-dimensionally preserved and articulated skeleton. It lies at the lower end of the size range for extant rollers. Salient diagnostic features of Septencoracias relative to other Coracii include the proportionally larger skull and the small, ovoid and dorsally positioned narial openings. Our discovery adds to the evidence that the Coracii had a widespread northern hemisphere distribution in the Eocene. Septencoracias is the oldest substantial record of the Picocoraciae and provides a reliable calibration point for molecular phylogenetic studies.

  18. An investigation on cylindrical imploding turbulent mixing

    International Nuclear Information System (INIS)

    Liao Haidong; Yang Libin; Zhang Xilin; Ouyang Kai; Li Jun

    2001-01-01

    The interfacial instability experiments in cylindrically convergent geometry are performed by imploding jelly liner with high pressure gases; and instability growth were observed with high-speed framing camera. The relevant 2D numerical simulation programs were developed and their results are in good agreement with those of experiments

  19. Wellposedness of a cylindrical shell model

    International Nuclear Information System (INIS)

    McMillan, C.

    1994-01-01

    We consider a well-known model of a thin cylindrical shell with dissipative feedback controls on the boundary in the form of forces, shears, and moments. We show that the resulting closed loop feedback problem generates a s.c. semigroup of contractions in the energy space

  20. Exact relativistic cylindrical solution of disordered radiation

    International Nuclear Information System (INIS)

    Fonseca Teixeira, A.F. da; Wolk, I.; Som, M.M.

    1976-05-01

    A source free disordered distribution of electromagnetic radiation is considered in Einstein' theory, and a time independent exact solution with cylindrical symmetry is obtained. The gravitation and pressure effects of the radiation alone are sufficient to give the distribution an equilibrium. A finite maximum concentration is found on the axis of symmetry, and decreases monotonically to zero outwards. Timelike and null geodesics are discussed

  1. Antibubbles and fine cylindrical sheets of air

    KAUST Repository

    Beilharz, D.

    2015-08-14

    Drops impacting at low velocities onto a pool surface can stretch out thin hemispherical sheets of air between the drop and the pool. These air sheets can remain intact until they reach submicron thicknesses, at which point they rupture to form a myriad of microbubbles. By impacting a higher-viscosity drop onto a lower-viscosity pool, we have explored new geometries of such air films. In this way we are able to maintain stable air layers which can wrap around the entire drop to form repeatable antibubbles, i.e. spherical air layers bounded by inner and outer liquid masses. Furthermore, for the most viscous drops they enter the pool trailing a viscous thread reaching all the way to the pinch-off nozzle. The air sheet can also wrap around this thread and remain stable over an extended period of time to form a cylindrical air sheet. We study the parameter regime where these structures appear and their subsequent breakup. The stability of these thin cylindrical air sheets is inconsistent with inviscid stability theory, suggesting stabilization by lubrication forces within the submicron air layer. We use interferometry to measure the air-layer thickness versus depth along the cylindrical air sheet and around the drop. The air film is thickest above the equator of the drop, but thinner below the drop and up along the air cylinder. Based on microbubble volumes, the thickness of the cylindrical air layer becomes less than 100 nm before it ruptures.

  2. Shear stresses around circular cylindrical openings

    NARCIS (Netherlands)

    Hoogenboom, P.C.J.; Van Weelden, C.; Blom, C.M.B.

    2010-01-01

    In this paper stress concentrations are studied around circular cylindrical openings or voids in a linear elastic continuum. The loading is such that a uniform shear stress occurs in the continuum, which is disturbed by the opening. The shear stress is in the direction of the centre axis of the

  3. On isotropic cylindrically symmetric stellar models

    International Nuclear Information System (INIS)

    Nolan, Brien C; Nolan, Louise V

    2004-01-01

    We attempt to match the most general cylindrically symmetric vacuum spacetime with a Robertson-Walker interior. The matching conditions show that the interior must be dust filled and that the boundary must be comoving. Further, we show that the vacuum region must be polarized. Imposing the condition that there are no trapped cylinders on an initial time slice, we can apply a result of Thorne's and show that trapped cylinders never evolve. This results in a simplified line element which we prove to be incompatible with the dust interior. This result demonstrates the impossibility of the existence of an isotropic cylindrically symmetric star (or even a star which has a cylindrically symmetric portion). We investigate the problem from a different perspective by looking at the expansion scalars of invariant null geodesic congruences and, applying to the cylindrical case, the result that the product of the signs of the expansion scalars must be continuous across the boundary. The result may also be understood in relation to recent results about the impossibility of the static axially symmetric analogue of the Einstein-Straus model

  4. A strong focussing cylindrical electrostatic quadrupole

    International Nuclear Information System (INIS)

    Sheng Yaochang

    1986-01-01

    The construction and performance of small cylindrical electrostatic quadrupole, which is installed in JM-400 pulse electrostatic accelerator, are described. This electrostatic quadrupole is not only used in neutron generator, but also suitable for ion injector as well as for low energy electron accelerator

  5. Cylindrical Induction Melter Modicon Control System

    International Nuclear Information System (INIS)

    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)

  6. A cylindrical furnace for absorption spectral studies

    Indian Academy of Sciences (India)

    A cylindrical furnace with three heating zones, capable of providing a temperature of 1100°C, has been fabricated to enable recording of absorption spectra of high temperature species. The temperature of the furnace can be controlled to ± 1°C of the set temperature. The salient feature of this furnace is that the material ...

  7. Antibubbles and fine cylindrical sheets of air

    KAUST Repository

    Beilharz, D.; Guyon, A.; Li, E.  Q.; Thoraval, M.-J.; Thoroddsen, Sigurdur T

    2015-01-01

    Drops impacting at low velocities onto a pool surface can stretch out thin hemispherical sheets of air between the drop and the pool. These air sheets can remain intact until they reach submicron thicknesses, at which point they rupture to form a myriad of microbubbles. By impacting a higher-viscosity drop onto a lower-viscosity pool, we have explored new geometries of such air films. In this way we are able to maintain stable air layers which can wrap around the entire drop to form repeatable antibubbles, i.e. spherical air layers bounded by inner and outer liquid masses. Furthermore, for the most viscous drops they enter the pool trailing a viscous thread reaching all the way to the pinch-off nozzle. The air sheet can also wrap around this thread and remain stable over an extended period of time to form a cylindrical air sheet. We study the parameter regime where these structures appear and their subsequent breakup. The stability of these thin cylindrical air sheets is inconsistent with inviscid stability theory, suggesting stabilization by lubrication forces within the submicron air layer. We use interferometry to measure the air-layer thickness versus depth along the cylindrical air sheet and around the drop. The air film is thickest above the equator of the drop, but thinner below the drop and up along the air cylinder. Based on microbubble volumes, the thickness of the cylindrical air layer becomes less than 100 nm before it ruptures.

  8. The positioning of federate sports in Portugal: handball, basketball, roller hockey and volleyball

    OpenAIRE

    Gonçalves, Celina; Correia, Abel

    2005-01-01

    Sport is constituted by a multiplicity of activities with different purposes, concepts and cultural representations. Before the increase of supply, Sports Federations need to understand the practitioners in relation to the several possibilities of practice and to position their sports according to their competitors. In this context, the purpose of this study is the positioning of team federate sports (handball, basketball, roller hockey and volleyball). According to Lindon et al.,...

  9. Neuromuscular Responses of Elite Skaters During Different Roller Figure Skating Jumps

    Directory of Open Access Journals (Sweden)

    Pantoja Patrícia Dias

    2014-07-01

    Full Text Available This study aimed to describe the neuromuscular activity of elite athletes who performed various roller figure skating jumps, to determine whether the muscle activation is greater during jumps with more rotations and in which phase the muscles are more active. This study also aimed to analyze if there is any difference in the muscle activity pattern between female and male skaters. Four elite skaters were evaluated, and each participated in two experimental sessions. During the first session, anthropometric data were collected, and the consent forms were signed. For the second session, neuromuscular data were collected during jumps, which were performed with skates at a rink. The following four roller figure skating jumps were evaluated: single Axel, double Axel, double Mapes and triple Mapes. The neuromuscular activity of the following seven muscles was obtained with an electromyograph which was fixed to the waist of each skater with a strap: biceps femoris, lateral gastrocnemius, tibialis anterior, rectus femoris, vastus lateralis, vastus medialis and gluteus maximus. The signal was transmitted wirelessly to a laptop. During the roller figure skating jumps, the lateral gastrocnemius, rectus femoris, vastus lateralis, biceps femoris and gluteus maximus, showed more activation during the jumps with more rotations, and the activation mainly occurred during the propulsion and flight phases. Female skaters demonstrated higher muscle activities in tibialis anterior, vastus lateralis, vastus medialis and gluteus maximus during the landing phase of the triple Mapes, when compared to their male counterparts. The results obtained in this study should be considered when planning training programs with specific exercises that closely resemble the roller figure skating jumps. This may be important for the success of elite skaters in competitions.

  10. The influence of increased distal loading on metabolic cost, efficiency, and kinematics of roller ski skating.

    Science.gov (United States)

    Bolger, Conor M; Bessone, Veronica; Federolf, Peter; Ettema, Gertjan; Sandbakk, Øyvind

    2018-01-01

    The purpose of the present study was to examine the influence of increased loading of the roller ski on metabolic cost, gross efficiency, and kinematics of roller ski skating in steep and moderate terrain, while employing two incline-specific techniques. Ten nationally ranked male cross-country skiers were subjected to four 7-minute submaximal intervals, with 0, 0.5, 1.0, and 1.5 kg added beneath the roller-ski in a randomized order. This was done on two separate days, with the G2 skating at 12% incline and 7 km/h speed and G3 skating at 5% incline and 14 km/h speed, respectively. At 12% incline, there was a significant increase in metabolic rate and a decrease in gross efficiency with added weight (P0.05). No changes in cycle characteristics were observed between the different ski loadings at either incline, although the lateral and vertical displacements of the foot/skis were slightly altered at 12% incline with added weight. In conclusion, the present study demonstrates that increased loading of the ski increases the metabolic cost and reduces gross efficiency during steep uphill roller skiing in G2 skating, whereas no significant effect was revealed when skating on relatively flat terrain in G3. Cycle characteristics remained unchanged across conditions at both inclines, whereas small adjustments in the displacement of the foot coincided with the efficiency changes in uphill terrain. The increased RPE values with added ski-weight at both inclines indicates that other factors than those measured here could have influenced effort and/or fatigue when lifting a heavier ski.

  11. Neuromuscular Responses of Elite Skaters During Different Roller Figure Skating Jumps

    Science.gov (United States)

    Pantoja, Patrícia Dias; Mello, André; Liedtke, Giane Veiga; Kanitz, Ana Carolina; Cadore, Eduardo Lusa; Pinto, Stephanie Santana; Alberton, Cristine Lima; Kruel, Luiz Fernando Martins

    2014-01-01

    This study aimed to describe the neuromuscular activity of elite athletes who performed various roller figure skating jumps, to determine whether the muscle activation is greater during jumps with more rotations and in which phase the muscles are more active. This study also aimed to analyze if there is any difference in the muscle activity pattern between female and male skaters. Four elite skaters were evaluated, and each participated in two experimental sessions. During the first session, anthropometric data were collected, and the consent forms were signed. For the second session, neuromuscular data were collected during jumps, which were performed with skates at a rink. The following four roller figure skating jumps were evaluated: single Axel, double Axel, double Mapes and triple Mapes. The neuromuscular activity of the following seven muscles was obtained with an electromyograph which was fixed to the waist of each skater with a strap: biceps femoris, lateral gastrocnemius, tibialis anterior, rectus femoris, vastus lateralis, vastus medialis and gluteus maximus. The signal was transmitted wirelessly to a laptop. During the roller figure skating jumps, the lateral gastrocnemius, rectus femoris, vastus lateralis, biceps femoris and gluteus maximus, showed more activation during the jumps with more rotations, and the activation mainly occurred during the propulsion and flight phases. Female skaters demonstrated higher muscle activities in tibialis anterior, vastus lateralis, vastus medialis and gluteus maximus during the landing phase of the triple Mapes, when compared to their male counterparts. The results obtained in this study should be considered when planning training programs with specific exercises that closely resemble the roller figure skating jumps. This may be important for the success of elite skaters in competitions. PMID:25114728

  12. Rereading "The Jack-Roller:" Hidden Histories in Sociology and Social Work

    Science.gov (United States)

    Shaw, Ian

    2009-01-01

    I revisit one of the iconic Chicago School studies, Clifford Shaw's "The Jack-Roller". A naive reading of Shaw's book leaves the reader with a sense of having been inducted into a melange of what we now know as "sociology" and "social work," but which to Shaw seems a coherent stance. I suggest that this is close to the heart of how things were,…

  13. Peculiarities of carrying capacity evaluations of cylindrical CFST columns with new type casing

    Directory of Open Access Journals (Sweden)

    Sinkovskaya Olena

    2017-01-01

    Full Text Available This paper deals with a cylindrical steel-concrete load-bearing unit. The feature of the unit is a steel mesh casing that is made from the expanded metal mesh. The optimal parameters of the suggested footing are determined taking into account anisotropy, i. e. different strength and rigidity in different directions that coincide and do not coincide with the direction of reinforcement. The optimal cell angle, when a casing deformation brings about maximum compression of a concrete core, is determined. Details for theoretical calculation of the bearing capacity of a cylindrical steel-concrete load-bearing unit are provided taking into consideration a complex three-dimensional structure of the suggested mesh casing. The validity of the calculations is confirmed by comparison them with the results of the Lira software package. The results of the calculations are provided in the form of the table showing the dependence of the adduced thickness of the plate on the longitudinal movement of the strip of the steel mesh casing. The dependencies to determine the adduced thickness of the mesh casing using the graphical method are provided for all the existing types of the mesh using concrete wedges or excluding them.

  14. The dynamic analysis of drum roll lathe for machining of rollers

    Science.gov (United States)

    Qiao, Zheng; Wu, Dongxu; Wang, Bo; Li, Guo; Wang, Huiming; Ding, Fei

    2014-08-01

    An ultra-precision machine tool for machining of the roller has been designed and assembled, and due to the obvious impact which dynamic characteristic of machine tool has on the quality of microstructures on the roller surface, the dynamic characteristic of the existing machine tool is analyzed in this paper, so is the influence of circumstance that a large scale and slender roller is fixed in the machine on dynamic characteristic of the machine tool. At first, finite element model of the machine tool is built and simplified, and based on that, the paper carries on with the finite element mode analysis and gets the natural frequency and shaking type of four steps of the machine tool. According to the above model analysis results, the weak stiffness systems of machine tool can be further improved and the reasonable bandwidth of control system of the machine tool can be designed. In the end, considering the shock which is caused by Z axis as a result of fast positioning frequently to feeding system and cutting tool, transient analysis is conducted by means of ANSYS analysis in this paper. Based on the results of transient analysis, the vibration regularity of key components of machine tool and its impact on cutting process are explored respectively.

  15. Scale up of diesel oil biodegradation in a baffled roller bioreactor.

    Science.gov (United States)

    Nikakhtari, Hossein; Song, Wanning; Kumar, Pardeep; Nemati, Mehdi; Hill, Gordon A

    2010-05-01

    Diesel oil is a suitable substance to represent petroleum contamination from accidental spills in operating and transportation facilities. Using a microbial culture enriched from a petroleum contaminated soil, biodegradation of diesel oil was carried out in 2.2, 55, and 220 L roller baffled bioreactors. The effects of bioreactor rotation speed (from 5 to 45 rpm) and liquid loading (from 18% to 73% of total volume) on the biodegradation of diesel oil were studied. In the small scale bioreactor (2.2L), the maximum rotation speed of 45 rpm resulted in the highest biodegradation rate with a first order biodegradation kinetic constant of 0.095 d(-1). In the larger scale bioreactors, rotation speed did not affect the biodegradation rate. Liquid loadings higher than 64% resulted in reduced biodegradation rates in the small scale bioreactor; however, in the larger roller bioreactors liquid loading did not affect the biodegradation rate. Biodegradation of diesel oil at 5 rpm and 73% loading is recommended for operating large scale roller baffled bioreactors. Under these conditions, high diesel oil concentrations up to 50 gL(-1) can be bioremediated at a rate of 1.61 gL(-1)d(-1). Copyright 2010 Elsevier Ltd. All rights reserved.

  16. Roller and Centrifugal Pumps: A Retrospective Comparison of Bleeding Complications in Extracorporeal Membrane Oxygenation.

    Science.gov (United States)

    Halaweish, Ihab; Cole, Adam; Cooley, Elaine; Lynch, William R; Haft, Jonathan W

    2015-01-01

    Centrifugal pumps are increasingly used for extracorporeal membrane oxygenation (ECMO) rather than roller pumps. However, shear forces induced by these types of continuousflow pumps are associated with acquired von Willebrand factor deficiency and bleeding complications. This study was undertaken to compare adverse bleeding complications with the use of centrifugal and roller pumps in patients on prolonged ECMO support. The records of all adult ECMO patients from June 2002 to 2013 were retrospectively reviewed using the University of Michigan Health System database and the Extracorporeal Life Support Organization registry, focusing on patients supported for at least 5 days. Ninety-five ECMO patients met criteria for inclusion (48 roller vs. 47 centrifugal pump). Indications included pulmonary (79%), cardiac (15%), and extracorporeal cardiopulmonary resuscitation (6%), without significant difference between the two groups. Despite lower heparin anticoagulation (10.9 vs. 13.7 IU/kg/hr) with centrifugal pumps, there was a higher incidence of nonsurgical bleeding (gastrointestinal, pulmonary, and neurological) in centrifugal pump patients (26.1 vs. 9.0 events/1,000 patient-days, p = 0.024). In conclusion, in our historical comparison, despite reduced anticoagulation, ECMO support using centrifugal pumps was associated with a higher incidence of nonsurgical bleeding. The mechanisms behind this are multifactorial and require further investigation.

  17. Effects of frequency on gross efficiency and performance in roller ski skating.

    Science.gov (United States)

    Leirdal, S; Sandbakk, O; Ettema, G

    2013-06-01

    The purpose of the present study was to examine the effect of frequency on efficiency and performance during G3 roller ski skating. Eight well-trained male cross-country skiers performed three submaximal 5-min speeds (10, 13, and 16 km/h) and a time-to-exhaustion (TTE) performance (at 20 km/h) using the G3 skating technique using freely chosen, high, and low frequency at all four speeds. All tests were done using roller skis on a large treadmill at 5% incline. Gross efficiency (GE) was calculated as power divided by metabolic rate. Power was calculated as the sum of power against frictional forces and power against gravity. Metabolic rate was calculated from oxygen consumption and blood lactate concentration. Freely chosen frequency increased from 60 to 70 strokes/min as speed increased from 10 to 20 km/h. GE increased with power. At high power (20 km/h performance test), both efficiency and performance were significantly reduced by high frequency. In regard to choice of frequency during G3 roller ski skating, cross-country skiers seems to be self-optimized both in relation to energy saving (efficiency) and performance (TTE). © 2011 John Wiley & Sons A/S.

  18. Intermittent stick-slip dynamics during the peeling of an adhesive tape from a roller.

    Science.gov (United States)

    Cortet, Pierre-Philippe; Dalbe, Marie-Julie; Guerra, Claudia; Cohen, Caroline; Ciccotti, Matteo; Santucci, Stéphane; Vanel, Loïc

    2013-02-01

    We study experimentally the fracture dynamics during the peeling at a constant velocity of a roller adhesive tape mounted on a freely rotating pulley. Thanks to a high speed camera, we measure, in an intermediate range of peeling velocities, high frequency oscillations between phases of slow and rapid propagation of the peeling fracture. This so-called stick-slip regime is well known as the consequence of a decreasing fracture energy of the adhesive in a certain range of peeling velocity coupled to the elasticity of the peeled tape. Simultaneously with stick slip, we observe low frequency oscillations of the adhesive roller angular velocity which are the consequence of a pendular instability of the roller submitted to the peeling force. The stick-slip dynamics is shown to become intermittent due to these slow pendular oscillations which produce a quasistatic oscillation of the peeling angle while keeping constant the peeling fracture velocity (averaged over each stick-slip cycle). The observed correlation between the mean peeling angle and the stick-slip amplitude questions the validity of the usually admitted independence with the peeling angle of the fracture energy of adhesives.

  19. Polar bears, Ursus maritimus

    Science.gov (United States)

    Rode, Karyn D.; Stirling, Ian

    2017-01-01

    Polar bears are the largest of the eight species of bears found worldwide and are covered in a pigment-free fur giving them the appearance of being white. They are the most carnivorous of bear species consuming a high-fat diet, primarily of ice-associated seals and other marine mammals. They range throughout the circumpolar Arctic to the southernmost extent of seasonal pack ice.

  20. EcoBears

    DEFF Research Database (Denmark)

    Nielsen, Nick; Pedersen, Sandra Bleuenn; Sørensen, Jens Ager

    2015-01-01

    In this paper, we introduce the EcoBears concept that aims to augment household appliances with functional and aesthetic features to promote their "use'' and "longevity of use'' to prevent their disposal. The EcoBears also aim to support the communication of environmental issues in the home setting....... We present our initial design and implementation of the EcoBears that consist of two bear modules (a mother and her cub). We also present our preliminary concept validations and lessons learned to be considered for future directions....

  1. Bearing restoration by grinding

    Science.gov (United States)

    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.

  2. Polar bears at risk

    Energy Technology Data Exchange (ETDEWEB)

    Norris, S.; Rosentrater, L.; Eid, P.M. [WWF International Arctic Programme, Oslo (Norway)

    2002-05-01

    Polar bears, the world's largest terrestrial carnivore, spend much of their lives on the arctic sea ice. This is where they hunt and move between feeding, denning, and resting areas. The world population, estimated at 22,000 bears, is made up of 20 relatively distinct populations varying in size from a few hundred to a few thousand animals. About 60 per cent of all polar bears are found in Canada. In general, the status of this species is stable, although there are pronounced differences between populations. Reductions in the extent and thickness of sea ice has lead the IUCN Polar Bear Specialist Group to describe climate change as one of the major threats facing polar bears today. Though the long-term effects of climate change will vary in different areas of the Arctic, impacts on the condition and reproductive success of polar bears and their prey are likely to be negative. Longer ice-free periods resulting from earlier break-up of sea ice in the spring and later formation in the fall is already impacting polar bears in the southern portions of their range. In Canada's Hudson Bay, for example, bears hunt on the ice through the winter and into early summer, after which the ice melts completely, forcing bears ashore to fast on stored fat until freeze-up in the fall. The time bears have on the ice to hunt and build up their body condition is cut short when the ice melts early. Studies from Hudson Bay show that for every week earlier that ice break-up occurs, bears will come ashore 10 kg lighter and in poorer condition. It is likely that populations of polar bears dividing their time between land and sea will be severely reduced and local extinctions may occur as greenhouse gas emissions continue to rise and sea ice melts. Expected changes in regional weather patterns will also impact polar bears. Rain in the late winter can cause maternity dens to collapse before females and cubs have departed, thus exposing occupants to the elements and to predators. Such

  3. Robotic Hand with Flexible Fingers for Grasping Cylindrical Objects

    OpenAIRE

    柴田, 瑞穂

    2015-01-01

    In this manuscript, a robotic hand for grasping a cylindrical object is proposed. This robotic hand has flexible fingers that can hold a cylindrical object during moving. We introduce a grasping strategy for a cylindrical object in terms of state transition graph. In this strategy the robotic hand picks up the cylindrical object utilizing a suction device before the hand grasp the object. We also design the flexible fingers; then, we investigate the validity of this robotic hand via several e...

  4. Thermohydrodynamic analysis of cryogenic liquid turbulent flow fluid film bearings, phase 2

    Science.gov (United States)

    Sanandres, Luis

    1994-01-01

    The Phase 2 (1994) Annual Progress Report presents two major report sections describing the thermal analysis of tilting- and flexure-pad hybrid bearings, and the unsteady flow and transient response of a point mass rotor supported on fluid film bearings. A literature review on the subject of two-phase flow in fluid film bearings and part of the proposed work for 1995 are also included. The programs delivered at the end of 1994 are named hydroflext and hydrotran. Both codes are fully compatible with the hydrosealt (1993) program. The new programs retain the same calculating options of hydrosealt plus the added bearing geometries, and unsteady flow and transient forced response. Refer to the hydroflext & hydrotran User's Manual and Tutorial for basic information on the analysis and instructions to run the programs. The Examples Handbook contains the test bearing cases along with comparisons with experimental data or published analytical values. The following major tasks were completed in 1994 (Phase 2): (1) extension of the thermohydrodynamic analysis and development of computer program hydroflext to model various bearing geometries, namely, tilting-pad hydrodynamic journal bearings, flexure-pad cylindrical bearings (hydrostatic and hydrodynamic), and cylindrical pad bearings with a simple elastic matrix (ideal foil bearings); (2) improved thermal model including radial heat transfer through the bearing stator; (3) calculation of the unsteady bulk-flow field in fluid film bearings and the transient response of a point mass rotor supported on bearings; and (4) a literature review on the subject of two-phase flows and homogeneous-mixture flows in thin-film geometries.

  5. Validation of a Functional Pyelocalyceal Renal Model for the Evaluation of Renal Calculi Passage While Riding a Roller Coaster.

    Science.gov (United States)

    Mitchell, Marc A; Wartinger, David D

    2016-10-01

    The identification and evaluation of activities capable of dislodging calyceal renal calculi require a patient surrogate or validated functional pyelocalyceal renal model. To evaluate roller coaster facilitation of calyceal renal calculi passage using a functional pyelocalyceal renal model. A previously described adult ureteroscopy and renoscopy simulator (Ideal Anatomic) was modified and remolded to function as a patient surrogate. Three renal calculi of different sizes from the patient who provided the original computed tomographic urograph on which the simulator was based were used. The renal calculi were suspended in urine in the model and taken for 20 rides on the Big Thunder Mountain Railroad roller coaster at Walt Disney World in Orlando, Florida. The roller coaster rides were analyzed using variables of renal calculi volume, calyceal location, model position on the roller coaster, and renal calculi passage. Sixty renal calculi rides were analyzed. Independent of renal calculi volume and calyceal location, front seating on the roller coaster resulted in a passage rate of 4 of 24. Independent of renal calculi volume and calyceal location, rear seating on the roller coaster resulted in a passage rate of 23 of 36. Independent of renal calculi volume in rear seating, calyceal location differed in passage rates, with an upper calyceal calculi passage rate of 100%; a middle calyceal passage rate of 55.6%; and a lower calyceal passage rate of 40.0%. The functional pyelocalyceal renal model serves as a functional patient surrogate to evaluate activities that facilitate calyceal renal calculi passage. The rear seating position on the roller coaster led to the most renal calculi passages.

  6. Cylindrical continuous martingales and stochastic integration in infinite dimensions

    NARCIS (Netherlands)

    Veraar, M.C.; Yaroslavtsev, I.S.

    2016-01-01

    In this paper we define a new type of quadratic variation for cylindrical continuous local martingales on an infinite dimensional spaces. It is shown that a large class of cylindrical continuous local martingales has such a quadratic variation. For this new class of cylindrical continuous local

  7. Investigation on Surface Roughness in Cylindrical Grinding

    Science.gov (United States)

    Rudrapati, Ramesh; Bandyopadhyay, Asish; Pal, Pradip Kumar

    2011-01-01

    Cylindrical grinding is a complex machining process. And surface roughness is often a key factor in any machining process while considering the machine tool or machining performance. Further, surface roughness is one of the measures of the technological quality of the product and is a factor that greatly influences cost and quality. The present work is related to some aspects of surface finish in the context of traverse-cut cylindrical grinding. The parameters considered have been: infeed, longitudinal feed and work speed. Taguchi quality design is used to design the experiments and to identify the significantly import parameter(s) affecting the surface roughness. By utilization of Response Surface Methodology (RSM), second order differential equation has been developed and attempts have also been made for optimization of the process in the context of surface roughness by using C- programming.

  8. Method of dismantling cylindrical structure by cutting

    International Nuclear Information System (INIS)

    Harada, Minoru; Mitsuo, Kohei; Yokota, Isoya; Nakamura, Kenjiro.

    1989-01-01

    This invention concerns a method of cutting and removing cylindrical structures, for example, iron-reinforced concrete materials such as thermal shielding walls in BWR type power plants into block-like form. That is, in a method of cutting and removing the cylindrical structure from the side of the outer wall, the structural material is cut from above to below successively in the axial direction and the circumferential direction by means abrasive jet by remote operation and cut into blocks each of a predetermined size. The cut out blocks are successively taken out. Cutting of the material from above to below by remote operation and taking out of small blocks causes no hazards to human body. Upon practicing the present invention, it is preferred to use a processing device for slurry and exhaust gases for preventing scattering of activated dismantled pieces or powdery dusts. (K.M.)

  9. Cylindrically converging blast waves in air

    Science.gov (United States)

    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.

  10. Escape and transmission probabilities in cylindrical geometry

    International Nuclear Information System (INIS)

    Bjerke, M.A.

    1980-01-01

    An improved technique for the generation of escape and transmission probabilities in cylindrical geometry was applied to the existing resonance cross section processing code ROLAIDS. The algorithm of Hwang and Toppel, [ANL-FRA-TM-118] (with modifications) was employed. The probabilities generated were found to be as accurate as those given by the method previously applied in ROLAIDS, while requiring much less computer core storage and CPU time

  11. The large cylindrical drift chamber of TASSO

    International Nuclear Information System (INIS)

    Boerner, H.; Fischer, H.M.; Hartmann, H.; Loehr, B.; Wollstadt, M.; Fohrmann, R.; Schmueser, P.; Cassel, D.G.; Koetz, U.; Kowalski, H.

    1980-03-01

    We have built and operated a large cylindrical drift chamber for the TASSO experiment at the DESY storage ring, PETRA. The chamber has a length of 3.5 m, a diameter of 2.5 m, and a total of 2340 drift cells. The cells are arranged in 15 concentric layers such that tracks can be reconstructed in three dimensions. A spatial resolution of 220 μm has been achieved for tracks of normal incidence on the drift cells. (orig.)

  12. Magnetic guns with cylindrical permanent magnets

    Czech Academy of Sciences Publication Activity Database

    Vokoun, David; Beleggia, M.; Heller, Luděk

    2012-01-01

    Roč. 324, č. 9 (2012), s. 1715-1719 ISSN 0304-8853 R&D Projects: GA ČR(CZ) GAP107/11/0391; GA AV ČR IAA100100920 Institutional research plan: CEZ:AV0Z10100520 Keywords : permanent magnet * cylindrical magnet * Earnshaw's theorem * magnetic gun * magnetostatic interaction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.826, year: 2012 http://www.sciencedirect.com/science/article/pii/S0304885311008997

  13. Transmission of infrared radiation through cylindrical waveguides

    International Nuclear Information System (INIS)

    Nucara, A.; Dore, P.; Calvani, P.; Cannavo', D.; Marcelli, A.

    1998-01-01

    Measurement of the transmittance of infrared radiation (v -1 ) through cylindrical waveguides are presented and discussed. The experimental results are compared with numerical simulations, obtained through conventional ray tracing programs. Finally, it' estimated the transmittance of a waveguide in the case of an infrared synchrotron radiation source. Are applied the results to the case of the DAΦNE collider, where a synchrotron radiation beamline for the far infrared is under construction

  14. Cylindric-like algebras and algebraic logic

    CERN Document Server

    Ferenczi, Miklós; Németi, István

    2013-01-01

    Algebraic logic is a subject in the interface between logic, algebra and geometry, it has strong connections with category theory and combinatorics. Tarski’s quest for finding structure in logic leads to cylindric-like algebras as studied in this book, they are among the main players in Tarskian algebraic logic. Cylindric algebra theory can be viewed in many ways:  as an algebraic form of definability theory, as a study of higher-dimensional relations, as an enrichment of Boolean Algebra theory, or, as logic in geometric form (“cylindric” in the name refers to geometric aspects). Cylindric-like algebras have a wide range of applications, in, e.g., natural language theory, data-base theory, stochastics, and even in relativity theory. The present volume, consisting of 18 survey papers, intends to give an overview of the main achievements and new research directions in the past 30 years, since the publication of the Henkin-Monk-Tarski monographs. It is dedicated to the memory of Leon Henkin.

  15. The analytic nodal method in cylindrical geometry

    International Nuclear Information System (INIS)

    Prinsloo, Rian H.; Tomasevic, Djordje I.

    2008-01-01

    Nodal diffusion methods have been used extensively in nuclear reactor calculations, specifically for their performance advantage, but also for their superior accuracy. More specifically, the Analytic Nodal Method (ANM), utilising the transverse integration principle, has been applied to numerous reactor problems with much success. In this work, a nodal diffusion method is developed for cylindrical geometry. Application of this method to three-dimensional (3D) cylindrical geometry has never been satisfactorily addressed and we propose a solution which entails the use of conformal mapping. A set of 1D-equations with an adjusted, geometrically dependent, inhomogeneous source, is obtained. This work describes the development of the method and associated test code, as well as its application to realistic reactor problems. Numerical results are given for the PBMR-400 MW benchmark problem, as well as for a 'cylindrisized' version of the well-known 3D LWR IAEA benchmark. Results highlight the improved accuracy and performance over finite-difference core solutions and investigate the applicability of nodal methods to 3D PBMR type problems. Results indicate that cylindrical nodal methods definitely have a place within PBMR applications, yielding performance advantage factors of 10 and 20 for 2D and 3D calculations, respectively, and advantage factors of the order of 1000 in the case of the LWR problem

  16. Fabrication of a roller type PDMS stamp using SU-8 concave molds and its application for roll contact printing

    International Nuclear Information System (INIS)

    Park, Jongho; Kim, Beomjoon

    2016-01-01

    Continuous fabrication of micropatterns at low-cost is attracting attention in various applications within industrial fields. To meet such demands, we have demonstrated a roll contact printing technique, using roller type polydimethylsiloxane (PDMS) stamps with roll-to-flat and roll-to-roll stages. Roller type PDMS stamps for roll contact printing were fabricated using a custom-made metal support and SU-8 microstructures fabricated on concave substrates as a mold. The molding/casting method which we developed here provided faster and easier fabrication than conventional methods for roller type stamps. Next, roll contact printing was performed using fabricated roller type PDMS stamps with roll-to-flat and roll-to-roll stages. Patterns with minimum widths of 3 μm and 2.1 μm were continuously fabricated for each stage, respectively. In addition, the relationship between applied pressures and dimensional changes of roll contact printed patterns was investigated. Finally, we confirmed that roll contact printing and the new fabrication method for roller stamps presented in this study demonstrated the feasibility for industrial applications. (paper)

  17. Increased Wear Resistance of Surfaces of Rotation Bearings Methods Strengthening-Smoothing Processing

    Directory of Open Access Journals (Sweden)

    A.A. Tkachuk

    2016-05-01

    Full Text Available Trends of modern engineering put forward higher requirements for quality bearings. This is especially true on production of bearings for special purposes with high speeds of rotation and resource. Much more opportunities in the technology management quality surface layers appear in the application of smoothing-strengthening methods, based on superficial plastic deformation. Working models of cutting lathes, grinders and tool smoothing sequence revealed the formation of operational parameters in the technological cycle of roller rings. The model of the dynamics of elastic deformation of the work piece tool helps identify actions radial force in the contact “surface – indenter.” Using mathematical modelling resolved a number of issues relevant process.

  18. General Case in Determining Center-To-Center Spacing Between the Screw and the Roller in a Roller Drive, and Initial Contact Point of Their Mating Thread Turns. Development of Calculation Method and Software

    Directory of Open Access Journals (Sweden)

    D. S. Blinov

    2017-01-01

    Full Text Available One of the most important trends in development of machine engineering is to improve load capacity of mechanisms, assemblies and parts without increasing their overall dimensions and weight. This is also relevant to the most promising items so far, i.e. orbital roller drives (ORD, which are the rotational-to-progressive motion converters widely used in vehicles. The previously published article suggested increasing a load capacity (by about 15% through reducing a thread turn section angle of the threaded ORD components and change of the radius of roller thread turn section outline. Due to such ORD modification, a number of the most critical ORD parameters are to be changed thereby demanding further research. Further, the article published suggests a method considering the abovementioned changes to calculate the dimensions of ORD main components and their tolerance ranges.Though this method being not complete as the increment of ORD center-to-center spacing in relation to its rated value, required for assembly, is unknown; and to determine the ORD center-to-center spacing increment, outer diameters of the roller and screw threads are to be known. Hence, these two methods are interconnected.This article presents the numerical calculation method, mathematical support and method to determine the increment of ORD center-to-center spacing and initial contact point of the mating roller and screw thread turns. Due to considerable scope of calculations, the method was turned into the software.Similar calculation methods and techniques were developed to a particular case, where the thread turn section angle of the threaded components was of 90°, and the roller thread turn section outline was a circular arc centered to the roller axis. Hence the developed numerical calculation method, mathematical support and technique refer to the general case which is to determine the ORD center-to-center spacing increment and initial contact point of the mating roller

  19. Abrasion Resistance and Mechanical Properties of Waste-Glass-Fiber-Reinforced Roller-compacted Concrete

    Science.gov (United States)

    Yildizel, S. A.; Timur, O.; Ozturk, A. U.

    2018-05-01

    The potential use of waste glass fibers in roller-compacted concrete (RCC) was investigated with the aim to improve its performance and reduce environmental effects. The research was focused on the abrasion resistance and compressive and flexural strengths of the reinforced concrete relative to those of reference mixes without fibers. The freeze-thaw resistance of RCC mixes was also examined. It was found that the use of waste glass fibers at a rate of 2 % increased the abrasion resistance of the RCC mixes considerably.

  20. Cylinder deactivation for valve trains with roller finger follower; Zylinderabschaltung fuer Ventiltriebe mit Rollenschlepphebeln

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, Hermann; Loch, Adam; Widmann, Richard [Mahle International GmbH, Stuttgart (Germany). Zentrale Voraussentwicklung; Kreussen, Gerhard; Rebbert, Martin [FEV Motorentechnik GmbH, Aachen (Germany). Abt. Dynamik; Meehsen, Daniel [FEV Motorentechnik GmbH, Aachen (Germany). Abt. Mechanik Versuch

    2009-04-15

    Cylinder deactivation increases efficiency of gasoline engines without negative effects in terms of exhaust gas emissions or driving dynamics. In particular, the advantageous cost/benefit ratio and great affinity to technologies currently used in gasoline engines support cylinder deactivation as the right path in meeting future market demands. The design and function of cylinder deactivation for valve trains with roller finger follower will be explained and examined with regard to functional aspects, such as stiffness, mass, and kinematic behavior. Based on initial results, design and production characteristics of this new technology are evaluated and technical control interactions in engine applications are presented by Mahle. (orig.)

  1. Macular hemorrhage after roller coaster riding in a single-eyed patient with congenital glaucoma

    Directory of Open Access Journals (Sweden)

    Dilek Guven

    Full Text Available ABSTRACT A 21-year-old female presented with a 4-day history of decreased vision in her only functional eye (right eye, OD. She had a history of multiple ocular surgeries in both eyes because of congenital glaucoma and had lost light perception in her left eye several years prior. Ophthalmological examination revealed 0.15 Snellen visual acuity, and fundoscopy revealed nearly total cupping and pallor of the optic disc and multiple retinal hemorrhagic foci in the macula in OD. Lesions spontaneously resolved over a few months. Gravitational forces during a roller coaster ride may have caused this macular hemorrhage.

  2. Use of flyash in roller compacted concrete for Ghatghar pumped storage scheme in Maharashtra

    Energy Technology Data Exchange (ETDEWEB)

    Damani, R.L.; Kshirsagar, S.L.; Narkhede, C.L. [MERI, Nashik (India)

    2003-07-01

    The paper described the use of 'Roller Compacted Concrete' (RCE) in which about 60% of the cement will be replaced by fly ash for construction of two storage dams - Upper dam and Lower dam in the Thane district of India. These are part of the Ghatghar Pumped Storage Scheme to generate hydropower. Fly ash from Eklahare and Dahav thermal power plant and processed fly ash, Pozzocrete 63 and 83b grade, all proved suitable for the RCC mix. 1 tab.

  3. VIRTUAL MODEL OF A ROLLER CONVEYOR INTEGRATED INTO A LOGISTIC FLOW

    Directory of Open Access Journals (Sweden)

    POPESCU Adrian

    2015-11-01

    Full Text Available In this article is presented, with the help of graphics, a logistic flow for palletizing and wrapping operations. The loaded pallets are transported by means of a roller conveyor. Creating the virtual model for the conveyer allows us to emphasize the compatibility elements between on the one hand the mechanical assemblies of the flow components and on the other hand the subassemblies of the conveyer structure. The paper has focused on the presentation of the conveyor specific assembly and how are placed the sensors on the mechanical structure of the conveyor. Finally, the main working phases are graphically presented within the flow, highlighting the loaded pallet positions in the flow.

  4. Lab-scale roller table mill for investigating the grinding behaviour of coal

    Energy Technology Data Exchange (ETDEWEB)

    Werner, V.; Zelkowski, J.; Schoenert, K. [Inst. for Energy Process Engineering and Fuel Technology and Inst. of Mineral Processing, Univ. Clausthal, Clausthal-Zellerfeld (Germany)

    1999-11-01

    The test mill is equipped with one roller. The material bed can be discharged completely after overroling. Grinding force, torque and gap width are measured. Cycle tests with three coals have been performed for simulating a closed circuit process. The grinding behaviour is characterized by the following relations: compaction of the particle bed and specific power draft vs. specific grinding force, production of fine material (dust), circuit factor, specific surface of the dust and specific work-input of the grinding circuit vs. specific power draft. (orig.)

  5. Corrective action decision document for the Roller Coaster Lagoons and North Disposal Trench (Corrective Action Unit Number 404)

    International Nuclear Information System (INIS)

    1997-01-01

    The North Disposal Trench, located north of the eastern most lagoon, was installed in 1963 to receive solid waste and construction debris from the Operation Roller Coaster man camp. Subsequent to Operation Roller Coaster, the trench continued to receive construction debris and range cleanup debris (including ordnance) from Sandia National Laboratories and other operators. A small hydrocarbon spill occurred during Voluntary Corrective Action (VCA) activities (VCA Spill Area) at an area associated with the North Disposal Trench Corrective Action Site (CAS). Remediation activities at this site were conducted in 1995. A corrective action investigation was conducted in September of 1996 following the Corrective Action Investigation Plan (CAIP); the detailed results of that investigation are presented in Appendix A. The Roller Coaster Lagoons and North Disposal Trench are located at the Tonopah Test Range (TTR), a part of the Nellis Air Force Range, which is approximately 225 kilometers (140 miles) northwest of Las Vegas, Nevada, by air

  6. Numerical Simulation of the Layer-Bylayer Destruction of Cylindrical Shells Under Explosive Loading

    Science.gov (United States)

    Abrosimov, N. A.; Novoseltseva, N. A.

    2015-09-01

    A technique of numerical analysis of the influence of reinforcement structure on the nature of the dynamic response and the process of layer-by-layer destruction of layered fiberglass cylindrical shells under an axisymmetric internal explosive loading is elaborated. The kinematic model of deformation of the laminate package is based on a nonclassical theory of shells. The geometric dependences are based on simple quadratic relations of the nonlinear theory of elasticity. The relationship between the stress and strain tensors are established by using Hooke's law for orthotropic bodies with account of degradation of stiffness characteristics of the multilayer composite due to the local destruction of some its elementary layers. An energetically consistent system of dynamic equations for composite cylindrical shells is obtained by minimizing the functional of total energy of the shell as a three-dimensional body. The numerical method for solving the formulated initial boundary-value problem is based on an explicit variational-difference scheme. Results confirming the reliability of the method used to analyze the influence of reinforcement structure on the character of destruction and the bearing capacity of pulse-loaded cylindrical shells are presented.

  7. Stress-deformed state of cylindrical specimens during indirect tensile strength testing

    Directory of Open Access Journals (Sweden)

    Levan Japaridze

    2015-10-01

    Full Text Available In this study, the interaction between cylindrical specimen made of homogeneous, isotropic, and linearly elastic material and loading jaws of any curvature is considered in the Brazilian test. It is assumed that the specimen is diametrically compressed by elliptic normal contact stresses. The frictional contact stresses between the specimen and platens are neglected. The analytical solution starts from the contact problem of the loading jaws of any curvature and cylindrical specimen. The contact width, corresponding loading angle (2θ0, and elliptical stresses obtained through solution of the contact problems are used as boundary conditions for a cylindrical specimen. The problem of the theory of elasticity for a cylinder is solved using Muskhelishvili's method. In this method, the displacements and stresses are represented in terms of two analytical functions of a complex variable. In the main approaches, the nonlinear interaction between the loading bearing blocks and the specimen as well as the curvature of their surfaces and the elastic parameters of their materials are taken into account. Numerical examples are solved using MATLAB to demonstrate the influence of deformability, curvature of the specimen and platens on the distribution of the normal contact stresses as well as on the tensile and compressive stresses acting across the loaded diameter. Derived equations also allow calculating the modulus of elasticity, total deformation modulus and creep parameters of the specimen material based on the experimental data of radial contraction of the specimen.

  8. Ultra-precision bearings

    CERN Document Server

    Wardle, F

    2015-01-01

    Ultra-precision bearings can achieve extreme accuracy of rotation, making them ideal for use in numerous applications across a variety of fields, including hard disk drives, roundness measuring machines and optical scanners. Ultraprecision Bearings provides a detailed review of the different types of bearing and their properties, as well as an analysis of the factors that influence motion error, stiffness and damping. Following an introduction to basic principles of motion error, each chapter of the book is then devoted to the basic principles and properties of a specific type of bearin

  9. Analysis of a cylindrical shell vibrating in a cylindrical fluid region

    International Nuclear Information System (INIS)

    Chung, H.; Turula, P.; Mulcahy, T.M.; Jendrzejczyk, J.A.

    1976-08-01

    Analytical and experimental methods are presented for evaluating the vibration characteristics of cylindrical shells such as the thermal liner of the Fast Flux Test Facility (FFTF) reactor vessel. The NASTRAN computer program is used to calculate the natural frequencies, mode shapes, and response to a harmonic loading of a thin, circular cylindrical shell situated inside a fluid-filled rigid circular cylinder. Solutions in a vacuum are verified with an exact solution method and the SAP IV computer code. Comparisons between analysis and experiment are made, and the accuracy and utility of the fluid-solid interaction package of NASTRAN is assessed

  10. Usefulness of extracorporeal membrane oxygenation using double roller pumps in a low body weight newborn: A novel strategy for mechanical circulatory support in an infant

    Directory of Open Access Journals (Sweden)

    Keisuke Nakanishi

    2016-01-01

    Full Text Available Extracorporeal membrane oxygenation (ECMO with a centrifugal pump requires a certain flow rate; therefore, its application for low body weight infants is frequently accompanied by oxygenator membrane malfunction and/or inadequate perfusion. To prevent low-flow associated complications, we report a case in which a novel system of dual roller pumps was used. A baby girl with a body mass index 0.25 m 2 , who experienced difficulty weaning from cardiopulmonary bypass after a Norwood-like operation, required an ECMO. Concerns for the tube lifespan reduction due to roller pump friction led to the use of a double roller pump circulation. The termination of ECMO during tube exchange is not needed, because circulation is maintained by another roller pump. The novel strategy of ECMO with double roller pumps will allow low perfusion rate to provide adequate circulatory support for low body weight patients.

  11. Modified Vertical Bearing Capacity for Circular Foundations in Sand Using Reduced Friction Angle

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Barari, Amin; Larsen, Kim André

    2012-01-01

    Recently Bucket foundation as a large cylindrical structure that is open as the base and closed at the top, has attracted much attention in offshore projects. In order to present relationship between vertical bearing capacity of a bucket foundation relative to the corresponding capacity of a circ......Recently Bucket foundation as a large cylindrical structure that is open as the base and closed at the top, has attracted much attention in offshore projects. In order to present relationship between vertical bearing capacity of a bucket foundation relative to the corresponding capacity...... of a circular plate, several loading tests on small scale bucket foundations including the circular surface footings are performed at Aalborg University. In current research, the vertical bearing capacity of circular surface footings is investigated using reduced friction angle. It is also presented a linear...

  12. DW_BEAR

    Data.gov (United States)

    Department of Homeland Security — Subset of BEAR (Bi-Weekly Examination Analysis and Reporting) data used for financial audit remediation reporting within the Coast Guard Business Intelligence (CGBI)...

  13. Fast, inexpensive, diffraction limited cylindrical microlenses

    International Nuclear Information System (INIS)

    Synder, J.J.; Reichert, P.

    1991-01-01

    We have developed a technique for fabricating fast, well corrected cylindrical microlenses. With this technique we have made a number of different microlenses with dimensions and focal lengths in the range of few hundred μm, and diffraction limited numerical apertures as high as 0.9. The microlenses are specifically designed for applications where they can increase the radiance or otherwise enhance the optical characteristics of laser diode light. The fabrication method we use is very versatile, and the microlenses produced this way would be very inexpensive in production quantities. 6 refs., 4 figs

  14. History of the small cylindrical melter

    International Nuclear Information System (INIS)

    Allen, T.L.; Iverson, D.C.; Plodinec, M.J.

    1985-08-01

    The small cylindrical melter (SCM) was designed to provide engineering data useful for operation and design of full-scale glass melters for vitrification of high-level radioactive waste. This melter was part of the research and development program for the Defense Waste Processing Facility (DWPF) at the Savannah River Plant (SRP). Extensive corrosion testing of melter materials of construction (Monofrax K3, Inconel 690), simulated radioactive waste glass characterization, and melter component development were conducted in support of the DWPF full-scale melter design. 66 figs., 14 tabs

  15. Acoustic propagation mode in a cylindrical plasma

    International Nuclear Information System (INIS)

    Ishida, Yoshio; Idehara, Toshitaka; Inada, Hideyo

    1975-01-01

    The sound velocity in a cylindrical plasma produced by a high frequency discharge is measured by an interferometer system. The result shows that the acoustic wave guide effect does exist in a neutral gas and in a plasma. It is found that the wave propagates in the mode m=2 in a rigid boundary above the cut-off frequency fsub(c) and in the mode m=0 below fsub(c). Because the mode m=0 is identical to a plane wave, the sound velocity in free space can be evaluated exactly. In the mode m=2, the sound velocity approaches the free space value, when the frequency increases sufficiently. (auth.)

  16. Cylindrical ionization chamber with compressed krypton

    International Nuclear Information System (INIS)

    Kuz'minov, V.V.; Novikov, V.M.; Pomanskii, A.A.; Pritychenko, B.V.; Viyar, J.; Garcia, E.; Morales, A.; Morales, J.; Nunes-Lagos, R.; Puimedon, J.; Saens, K.; Salinas, A.; Sarsa, M.

    1993-01-01

    A cylindrical ionization chamber with a grid is used to search for double positron decay and atomic electron conversion to a positron in 78 Kr. Krypton is the working gas material of the chamber. The spectrometric characteristics of the chamber filled with krypton and xenon are presented. The energy resolution is 2.1% for an energy of 1.84 MeV (the source of γ-quanta is 88 Y) when the chamber is filled with a mixture of Kr+0.2% H 2 under a pressure of 25 atm

  17. Cullet Manufacture Using the Cylindrical Induction Melter

    International Nuclear Information System (INIS)

    Miller, D. H.

    2000-01-01

    The base process for vitrification of the Am/Cm solution stored in F-canyon uses 25SrABS cullet as the glass former. A small portion of the cullet used in the SRTC development work was purchased from Corning while the majority was made in the 5 inch Cylindrical Induction Melter (CIM5). Task 1.01 of TTR-NMSS/SE-006, Additional Am-Cm Process Development Studies, requested that a process for the glass former (cullet) fabrication be specified. This report provides the process details for 25SrAB cullet production thereby satisfying Task 1.01

  18. Stability analysis of cylindrical Vlasov equilibria

    International Nuclear Information System (INIS)

    Short, R.W.

    1979-01-01

    A general method of stability analysis is described which may be applied to a large class of such problems, namely those which are described dynamically by the Vlasov equation, and geometrically by cylindrical symmetry. The method is presented for the simple case of the Vlasov-Poisson (electrostatic) equations, and the results are applied to a calculation of the lower-hybrid-drift instability in a plasma with a rigid rotor distribution function. The method is extended to the full Vlasov-Maxwell (electromagnetic) equations. These results are applied to a calculation of the instability of the extraordinary electromagnetic mode in a relativistic E-layer interacting with a background plasma

  19. Enhanced Performance of Cylindrical Hall Thrusters

    International Nuclear Information System (INIS)

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

    2007-01-01

    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

  20. Waves in inhomogeneous plasma of cylindrical geometry

    International Nuclear Information System (INIS)

    Rebut, P.H.

    1966-01-01

    The conductivity tensor of a hot and inhomogeneous plasma has been calculated for a cylindrical geometry using Vlasov equations. The method used consists in a perturbation method involving the first integrals of the unperturbed movement. The conductivity tensor will be particularly useful for dealing with stability problems. In the case of a cold plasma the wave equation giving the electric fields as a function of the radius is obtained. This equation shows the existence of resonant layers which lead to an absorption analogous to the Landau absorption in a hot plasma. (author) [fr

  1. Rolling bearing analysis

    CERN Document Server

    Harris, Tedric A

    2001-01-01

    One of the most well-known experts in the field brings cutting-edge research to practitioners in the new edition of this important reference. Covers the improved mathematical calculations for rolling bearing endurance developed by the American Society of Mechanical Engineers and the Society of Lubrication and Tribology Engineers. Updated with new material on Condition-Based Maintenance, new testing methods, and new bearing materials.

  2. Gear bearing drive

    Science.gov (United States)

    Mavroidis, Constantinos (Inventor); Vranish, John M. (Inventor); Weinberg, Brian (Inventor)

    2011-01-01

    A gear bearing drive provides a compact mechanism that operates as an actuator providing torque and as a joint providing support. The drive includes a gear arrangement integrating an external rotor DC motor within a sun gear. Locking surfaces maintain the components of the drive in alignment and provide support for axial loads and moments. The gear bearing drive has a variety of applications, including as a joint in robotic arms and prosthetic limbs.

  3. Stochastic Resonance algorithms to enhance damage detection in bearing faults

    Directory of Open Access Journals (Sweden)

    Castiglione Roberto

    2015-01-01

    Full Text Available Stochastic Resonance is a phenomenon, studied and mainly exploited in telecommunication, which permits the amplification and detection of weak signals by the assistance of noise. The first papers on this technique are dated early 80 s and were developed to explain the periodically recurrent ice ages. Other applications mainly concern neuroscience, biology, medicine and obviously signal analysis and processing. Recently, some researchers have applied the technique for detecting faults in mechanical systems and bearings. In this paper, we try to better understand the conditions of applicability and which is the best algorithm to be adopted for these purposes. In fact, to get the methodology profitable and efficient to enhance the signal spikes due to fault in rings and balls/rollers of bearings, some parameters have to be properly selected. This is a problem since in system identification this procedure should be as blind as possible. Two algorithms are analysed: the first exploits classical SR with three parameters mutually dependent, while the other uses Woods-Saxon potential, with three parameters yet but holding a different meaning. The comparison of the performances of the two algorithms and the optimal choice of their parameters are the scopes of this paper. Algorithms are tested on simulated and experimental data showing an evident capacity of increasing the signal to noise ratio.

  4. Load responsive hydrodynamic bearing

    Science.gov (United States)

    Kalsi, Manmohan S.; Somogyi, Dezso; Dietle, Lannie L.

    2002-01-01

    A load responsive hydrodynamic bearing is provided in the form of a thrust bearing or journal bearing for supporting, guiding and lubricating a relatively rotatable member to minimize wear thereof responsive to relative rotation under severe load. In the space between spaced relatively rotatable members and in the presence of a liquid or grease lubricant, one or more continuous ring shaped integral generally circular bearing bodies each define at least one dynamic surface and a plurality of support regions. Each of the support regions defines a static surface which is oriented in generally opposed relation with the dynamic surface for contact with one of the relatively rotatable members. A plurality of flexing regions are defined by the generally circular body of the bearing and are integral with and located between adjacent support regions. Each of the flexing regions has a first beam-like element being connected by an integral flexible hinge with one of the support regions and a second beam-like element having an integral flexible hinge connection with an adjacent support region. A least one local weakening geometry of the flexing region is located intermediate the first and second beam-like elements. In response to application of load from one of the relatively rotatable elements to the bearing, the beam-like elements and the local weakening geometry become flexed, causing the dynamic surface to deform and establish a hydrodynamic geometry for wedging lubricant into the dynamic interface.

  5. Significant changes in the skin microbiome mediated by the sport of roller derby

    Directory of Open Access Journals (Sweden)

    James F. Meadow

    2013-03-01

    Full Text Available Diverse bacterial communities live on and in human skin. These complex communities vary by skin location on the body, over time, between individuals, and between geographic regions. Culture-based studies have shown that human to human and human to surface contact mediates the dispersal of pathogens, yet little is currently known about the drivers of bacterial community assembly patterns on human skin. We hypothesized that participation in a sport involving skin to skin contact would result in detectable shifts in skin bacterial community composition. We conducted a study during a flat track roller derby tournament, and found that teammates shared distinct skin microbial communities before and after playing against another team, but that opposing teams’ bacterial communities converged during the course of a roller derby bout. Our results are consistent with the hypothesis that the human skin microbiome shifts in composition during activities involving human to human contact, and that contact sports provide an ideal setting in which to evaluate dispersal of microorganisms between people.

  6. Performance of integrated systems of automated roller shade systems and daylight responsive dimming systems

    Energy Technology Data Exchange (ETDEWEB)

    Park, Byoung-Chul; Choi, An-Seop; Jeong, Jae-Weon [Department of Architectural Engineering, Sejong University, Kunja-Dong, Kwangjin-Gu, Seoul (Korea, Republic of); Lee, Eleanor S. [Building Technologies Department, Lawrence Berkeley National Laboratory, Berkeley, CA (United States)

    2011-03-15

    Daylight responsive dimming systems have been used in few buildings to date because they require improvements to improve reliability. The key underlying factor contributing to poor performance is the variability of the ratio of the photosensor signal to daylight workplane illuminance in accordance with sun position, sky condition, and fenestration condition. Therefore, this paper describes the integrated systems between automated roller shade systems and daylight responsive dimming systems with an improved closed-loop proportional control algorithm, and the relative performance of the integrated systems and single systems. The concept of the improved closed-loop proportional control algorithm for the integrated systems is to predict the varying correlation of photosensor signal to daylight workplane illuminance according to roller shade height and sky conditions for improvement of the system accuracy. In this study, the performance of the integrated systems with two improved closed-loop proportional control algorithms was compared with that of the current (modified) closed-loop proportional control algorithm. In the results, the average maintenance percentage and the average discrepancies of the target illuminance, as well as the average time under 90% of target illuminance for the integrated systems significantly improved in comparison with the current closed-loop proportional control algorithm for daylight responsive dimming systems as a single system. (author)

  7. Decreasing inventory of a cement factory roller mill parts using reliability centered maintenance method

    Science.gov (United States)

    Witantyo; Rindiyah, Anita

    2018-03-01

    According to data from maintenance planning and control, it was obtained that highest inventory value is non-routine components. Maintenance components are components which procured based on maintenance activities. The problem happens because there is no synchronization between maintenance activities and the components required. Reliability Centered Maintenance method is used to overcome the problem by reevaluating maintenance activities required components. The case chosen is roller mill system because it has the highest unscheduled downtime record. Components required for each maintenance activities will be determined by its failure distribution, so the number of components needed could be predicted. Moreover, those components will be reclassified from routine component to be non-routine component, so the procurement could be carried out regularly. Based on the conducted analysis, failure happens in almost every maintenance task are classified to become scheduled on condition task, scheduled discard task, schedule restoration task and no schedule maintenance. From 87 used components for maintenance activities are evaluated and there 19 components that experience reclassification from non-routine components to routine components. Then the reliability and need of those components were calculated for one-year operation period. Based on this invention, it is suggested to change all of the components in overhaul activity to increase the reliability of roller mill system. Besides, the inventory system should follow maintenance schedule and the number of required components in maintenance activity so the value of procurement will be decreased and the reliability system will increase.

  8. Lake Robertson hydroelectric project. Construction of a roller compacted concrete dam

    Energy Technology Data Exchange (ETDEWEB)

    Labelle, M.; Robitaille, F. [Hydro-Quebec, Montreal, PQ (Canada)

    1995-12-31

    Construction of the Lake Robertson hydroelectric project on Quebec`s Lower North Shore was discussed in detail. The dam and powerhouse, located on the HaHa River, consists of a 134 m long concrete gravity dam, and a 21 MW powerhouse with two 69 kV transmission lines and four substations. The climate, terrain, and geography of the region, all of them characterized as severe, and the logistics of construction of the dam and power lines, aggravated by the isolation and severe conditions at the site, were described. The roller compacted concrete design and construction were noted, and justification for a concrete dam over an earth-fill dam was provided. Economics, properties, and composition of the roller compacted concrete (RCC) were examined, and control test results for the RCC concrete were provided. The use of RCC for the Lake Robertson development was described as successful in terms of the quality, watertightness, and completion time. The experience gained by the participants will make it possible to offer RCC as an alternative on various other projects. 2 figs.

  9. Automatic Identification of Subtechniques in Skating-Style Roller Skiing Using Inertial Sensors

    Science.gov (United States)

    Sakurai, Yoshihisa; Fujita, Zenya; Ishige, Yusuke

    2016-01-01

    This study aims to develop and validate an automated system for identifying skating-style cross-country subtechniques using inertial sensors. In the first experiment, the performance of a male cross-country skier was used to develop an automated identification system. In the second, eight male and seven female college cross-country skiers participated to validate the developed identification system. Each subject wore inertial sensors on both wrists and both roller skis, and a small video camera on a backpack. All subjects skied through a 3450 m roller ski course using a skating style at their maximum speed. The adopted subtechniques were identified by the automated method based on the data obtained from the sensors, as well as by visual observations from a video recording of the same ski run. The system correctly identified 6418 subtechniques from a total of 6768 cycles, which indicates an accuracy of 94.8%. The precisions of the automatic system for identifying the V1R, V1L, V2R, V2L, V2AR, and V2AL subtechniques were 87.6%, 87.0%, 97.5%, 97.8%, 92.1%, and 92.0%, respectively. Most incorrect identification cases occurred during a subtechnique identification that included a transition and turn event. Identification accuracy can be improved by separately identifying transition and turn events. This system could be used to evaluate each skier’s subtechniques in course conditions. PMID:27049388

  10. Automatic Identification of Subtechniques in Skating-Style Roller Skiing Using Inertial Sensors

    Directory of Open Access Journals (Sweden)

    Yoshihisa Sakurai

    2016-04-01

    Full Text Available This study aims to develop and validate an automated system for identifying skating-style cross-country subtechniques using inertial sensors. In the first experiment, the performance of a male cross-country skier was used to develop an automated identification system. In the second, eight male and seven female college cross-country skiers participated to validate the developed identification system. Each subject wore inertial sensors on both wrists and both roller skis, and a small video camera on a backpack. All subjects skied through a 3450 m roller ski course using a skating style at their maximum speed. The adopted subtechniques were identified by the automated method based on the data obtained from the sensors, as well as by visual observations from a video recording of the same ski run. The system correctly identified 6418 subtechniques from a total of 6768 cycles, which indicates an accuracy of 94.8%. The precisions of the automatic system for identifying the V1R, V1L, V2R, V2L, V2AR, and V2AL subtechniques were 87.6%, 87.0%, 97.5%, 97.8%, 92.1%, and 92.0%, respectively. Most incorrect identification cases occurred during a subtechnique identification that included a transition and turn event. Identification accuracy can be improved by separately identifying transition and turn events. This system could be used to evaluate each skier’s subtechniques in course conditions.

  11. The Selection of Materials for Roller Chains From The Perspective Of Manufacturing Process

    Directory of Open Access Journals (Sweden)

    Rahmat Saptono

    2010-10-01

    Full Text Available The selection of materials for an engineering component is not only requested by its design function and shape, but also the sequence through which it is manufactured. The manufacturing operation of roller chains involves drawing and trimming processes aimed at producing semi-finished chain drives component with a well-standardized dimension. In addition to final combination of properties required by design constraints, the ability of materials to be formed into a desired shape and geometry without failure is also critical. The objective of materials selection should therefore involve additional attributes that are not typically  accommodated by the standard procedure of materials selection. The present paper deals with the selection of materials for roller chains from the perspective of manufacturing process. Ears and un-uniform wall thickness have been identified as a key problem in the mass production of component. Provided all process parameters were established, the  anisotropy factor of materials is critical. Simulative test can be reasonably used to obtain material performance indices that can be added up to the standard procedure of material selection. Of three commercially available steel grades evaluated with regard to the criteria defined, one grade is more suitable for the present objective.

  12. Assesment on Reproductive Performance and Hormonal Studies in Rural Women Beedi Rollers in Jagitial District of Telangana State

    Directory of Open Access Journals (Sweden)

    Vanitha Baluka

    2017-10-01

    Full Text Available Beedi manufacturing is the second largest industry in India. It provides employment to millions of women mostly from the poor socioeconomic class. In North region of Telangana, beedi rolling is a major occupation for illiterate women in many villages. It may affect due to the inhalation of unfiltered tobacco dust and volatile and toxic components of tobacco. Biomonitoring of women beedi rollers and their reproductive performance assessment is necessary to take prevention/control the reproduction failure and carcinogen effect on cervical system. Continuous exposed to unfiltered tobacco dust may have systemic effect and lead to many disorders including hormone defects and reproductive health problems. Although studies have been carried out on beedi industry workers and tobacco smoke exposed people at national and international level, no such studies were carried out on women beedi rollers living in rural areas in Telangana State. Hence, this investigation is attempted to understand the study is find to association with hormonal levels and reproductive outcome in rural women beedi rollers of reproductive age in North Telangana. Statistical analysis was done for the obtained results to find the significance between the two groups for the reproductive outcome and Hormonal Studies. Total 50 women (married who are exposed minimum 6-10 years to the unfiltered tobacco dust beedi rollers in the age group of 25 to 45 years from villages of Jagitial district were enrolled for this study. 50 equal numbers of women in the same age group belonging to the same socio economic status and not exposed occupationally to chemical and physical agents was selected for comparison (control group. Estroidal, Progesterone the T3, T4 and TSH levels were measured found significantly T3, T4 levels were low in the beedi rollers, compared the controls. TSH levels were found to be higher in the beedi rollers. Estroidal and progesterone levels were obtained non

  13. Sealed rotary hearth furnace with central bearing support

    Science.gov (United States)

    Docherty, James P.; Johnson, Beverly E.; Beri, Joseph

    1989-01-01

    The furnace has a hearth which rotates inside a stationary closed chamber and is supported therein on vertical cylindrical conduit which extends through the furnace floor and is supported by a single center bearing. The charge is deposited through the furnace roof on the rim of the hearth as it rotates and is moved toward the center of the hearth by rabbles. Externally generated hot gases are introduced into the furnace chamber below the hearth and rise through perforations in the hearth and up through the charge. Exhaust gases are withdrawn through the furnace roof. Treated charge drops from a center outlet on the hearth into the vertical cylindrical conduit which extends downwardly through the furnace floor to which it is also sealed.

  14. Multimode interaction in axially excited cylindrical shells

    Directory of Open Access Journals (Sweden)

    Silva F. M. A.

    2014-01-01

    Full Text Available Cylindrical shells exhibit a dense frequency spectrum, especially near the lowest frequency range. In addition, due to the circumferential symmetry, frequencies occur in pairs. So, in the vicinity of the lowest natural frequencies, several equal or nearly equal frequencies may occur, leading to a complex dynamic behavior. So, the aim of the present work is to investigate the dynamic behavior and stability of cylindrical shells under axial forcing with multiple equal or nearly equal natural frequencies. The shell is modelled using the Donnell nonlinear shallow shell theory and the discretized equations of motion are obtained by applying the Galerkin method. For this, a modal solution that takes into account the modal interaction among the relevant modes and the influence of their companion modes (modes with rotational symmetry, which satisfies the boundary and continuity conditions of the shell, is derived. Special attention is given to the 1:1:1:1 internal resonance (four interacting modes. Solving numerically the governing equations of motion and using several tools of nonlinear dynamics, a detailed parametric analysis is conducted to clarify the influence of the internal resonances on the bifurcations, stability boundaries, nonlinear vibration modes and basins of attraction of the structure.

  15. Forced Vibration Analysis for a FGPM Cylindrical Shell

    Directory of Open Access Journals (Sweden)

    Hong-Liang Dai

    2013-01-01

    Full Text Available This article presents an analytical study for forced vibration of a cylindrical shell which is composed of a functionally graded piezoelectric material (FGPM. The cylindrical shell is assumed to have two-constituent material distributions through the thickness of the structure, and material properties of the cylindrical shell are assumed to vary according to a power-law distribution in terms of the volume fractions for constituent materials, the exact solution for the forced vibration problem is presented. Numerical results are presented to show the effect of electric excitation, thermal load, mechanical load and volume exponent on the static and force vibration of the FGPM cylindrical shell. The goal of this investigation is to optimize the FGPM cylindrical shell in engineering, also the present solution can be used in the forced vibration analysis of cylindrical smart elements.

  16. Conical Magnetic Bearings Developed for Active Stall Control in Gas Turbine Engines

    Science.gov (United States)

    Trudell, Jeffrey J.; Kascak, Albert F.; Provenza, Andrew J.; Buccieri, Carl J.

    2004-01-01

    replaces the ball bearing in front of the compressor, and the second replaces the roller bearing behind the burner. The rig was made operational to 10,000 rpm under Smart Efficient Components funding, and both position and current adaptive vibration control have been demonstrated. Upon program completion, recommendations will be made as to the efficacy of the conical magnetic bearing for active stall control.

  17. Note: Electrochemical etching of cylindrical nanoprobes using a vibrating electrolyte

    International Nuclear Information System (INIS)

    Wang, Yufeng; Zeng, Yongbin; Qu, Ningsong; Zhu, Di

    2015-01-01

    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

  18. Climate Drives Polar Bear Origins

    Science.gov (United States)

    In their provocative analysis of northern bears (“Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage,” Reports, 20 April, p. 344), F. Hailer et al. use independent nuclear loci to show that polar bears originated during the middle Pleistocene, rather than during t...

  19. Watchable Wildlife: The Black Bear

    Science.gov (United States)

    Lynn L. Rogers

    1992-01-01

    Black bears are the bears people most often encounter. Black bears live in forests over much of North America, unlike grizzlies that live only in Alaska, northern and western Canada, and the northern Rocky Mountains. This brochure presents the latest information on black bear life and how this species responds to an ever-increasing number of campers, hikers, and...

  20. Magnetostatic interactions and forces between cylindrical permanent magnets

    International Nuclear Information System (INIS)

    Vokoun, David; Beleggia, Marco; Heller, Ludek; Sittner, Petr

    2009-01-01

    Permanent magnets of various shapes are often utilized in magnetic actuators, sensors or releasable magnetic fasteners. Knowledge of the magnetic force is required to control devices reliably. Here, we introduce an analytical expression for calculating the attraction force between two cylindrical permanent magnets on the assumption of uniform magnetization. Although the assumption is not fulfilled exactly in cylindrical magnets, we obtain a very good agreement between the calculated and measured forces between two identical cylindrical magnets and within an array of NdFeB cylindrical magnets.

  1. Tribology of alternative bearings.

    Science.gov (United States)

    Fisher, John; Jin, Zhongmin; Tipper, Joanne; Stone, Martin; Ingham, Eileen

    2006-12-01

    The tribological performance and biological activity of the wear debris produced has been compared for highly cross-linked polyethylene, ceramic-on-ceramic, metal-on-metal, and modified metal bearings in a series of in vitro studies from a single laboratory. The functional lifetime demand of young and active patients is 10-fold greater than the estimated functional lifetime of traditional polyethylene. There is considerable interest in using larger diameter heads in these high demand patients. Highly cross-linked polyethylene show a four-fold reduction in functional biological activity. Ceramic-on-ceramic bearings have the lowest wear rates and least reactive wear debris. The functional biological activity is 20-fold lower than with highly cross-linked polyethylene. Hence, ceramic-on-ceramic bearings address the tribological lifetime demand of highly active patients. Metal-on-metal bearings have substantially lower wear rates than highly cross-linked polyethylene and wear decreases with head diameter. Bedding in wear is also lower with reduced radial clearance. Differential hardness ceramic-on-metal bearings and the application of ceramic-like coatings reduce metal wear and ion levels.

  2. Corrective action plan for CAU No. 404: Roller Coaster Sewage Lagoons and North Disposal Trench, Tonopah Test Range

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-07-01

    This Corrective Action Plan (CAP) provides the selected corrective action alternative and proposes the closure implementation methodology for the Roller Coaster Sewage Lagoons and North Disposal Trench Corrective Action Unit (CAU) No. 404. The site is located on the Tonopah Test Range. CAU 404 consists of two Corrective Action Sites (CAS): the Roller Coaster Lagoons (CAS No TA-03-001-TA-RC) and the North Disposal Trench (CAS No TA-21-001-TA-RC). A site map of the lagoons and trench is provided. The Roller Coaster Sewage Lagoons are comprised of two unlined lagoons that received liquid sanitary waste in 1963 from the Operation Roller Coaster Man Camp and debris from subsequent construction and range cleanup activities. The North Disposal Trench was excavated in approximately 1963 and received solid waste and debris from the man camp and subsequent construction and range cleanup activities. A small hydrocarbon spill occurred during the 1995 Voluntary Corrective Action (VCA) activities in an area associated with the North Disposal Trench CAS.

  3. Fire ants protect mealybugs against their natural enemies by utilizing the leaf shelters constructed by the leaf roller Sylepta derogata.

    Directory of Open Access Journals (Sweden)

    Aiming Zhou

    Full Text Available The importance of mutualism is receiving more attention in community ecology. In this study, the fire ant Solenopsis invicta was found to take advantage of the shelters constructed by the leaf roller Sylepta derogata to protect mealybugs (Phenacoccus solenopsis against their natural enemies. This protective effect of fire ant tending on the survival of mealybugs in shelters was observed when enemies and leaf rollers were simultaneously present. Specifically, fire ants moved the mealybugs inside the shelters produced by S. derogata on enemy-infested plants. Compared with that in plants without ants, the survival of mealybugs in shelters in the presence of natural enemies in plants with ants markedly improved. Both the protection of ants and the shelters provided by leaf rollers did not affect the survival of mealybugs in the absence of enemies in plants. Ants and leaf rollers significantly improved the survival of mealybugs in predator-infested plants, whereas no such improvement was observed in parasitoid-infested ones.

  4. To Enhance the Fire Resistance Performance of High-Speed Steel Roller Door with Water Film System

    Directory of Open Access Journals (Sweden)

    De-Hua Chung

    2015-01-01

    Full Text Available The structure of high-speed roller door with water film has improved in this study. The flameproof water film system is equipped with a water circulating device to reduce the water consumption of water film system. The water film is generated at the roller box of the high-speed roller door in this study. The heating test is done with the full-scale heating furnace. Both cases of the water film on unexposed surface and water film on exposed surface passed the fire resistance test based on ISO 834, proving that the high-speed roller door with water film system has 120A fire resistance period. The main findings indicate that the water film on exposed surface shows that as the amount of water film evaporated by high temperature inside the furnace must be greater than the evaporation capacity of water film on unexposed surface, the required water supply is 660 L more than the water film on unexposed surface.

  5. Corrective action plan for CAU No. 404: Roller Coaster Sewage Lagoons and North Disposal Trench, Tonopah Test Range

    International Nuclear Information System (INIS)

    1997-07-01

    This Corrective Action Plan (CAP) provides the selected corrective action alternative and proposes the closure implementation methodology for the Roller Coaster Sewage Lagoons and North Disposal Trench Corrective Action Unit (CAU) No. 404. The site is located on the Tonopah Test Range. CAU 404 consists of two Corrective Action Sites (CAS): the Roller Coaster Lagoons (CAS No TA-03-001-TA-RC) and the North Disposal Trench (CAS No TA-21-001-TA-RC). A site map of the lagoons and trench is provided. The Roller Coaster Sewage Lagoons are comprised of two unlined lagoons that received liquid sanitary waste in 1963 from the Operation Roller Coaster Man Camp and debris from subsequent construction and range cleanup activities. The North Disposal Trench was excavated in approximately 1963 and received solid waste and debris from the man camp and subsequent construction and range cleanup activities. A small hydrocarbon spill occurred during the 1995 Voluntary Corrective Action (VCA) activities in an area associated with the North Disposal Trench CAS

  6. Influence of Surface-profile and Movement-path of Roller on Thickness Thinning during Multi-pass Deep Drawing Spinning

    Directory of Open Access Journals (Sweden)

    Xia Qinxiang

    2016-01-01

    Full Text Available Over thinning is a serious defect influencing the forming quality of spun workpiece during multi-pass deep drawing spinning. Surface-profile and movement-path of roller are the key factors influencing the thinning ratio of wall thickness of spun workpiece. The influence of surface-profile and movement-path of roller on thickness thinning were studied based on numerical simulation and experimental research, four groups of forming experiments were carried out under the combination of the different surface-profile of roller (R12 and R25-12 and movement-path of roller (spinning from the bottom of the blank and spinning from the middle of the blank. The results show that both the surface-profile and movement-path of roller have great influence on wall thickness thinning during multi-pass deep drawing spinning; and compared with the movement-path of roller, the influence of surface-profile of roller is more significant. The experimental results conform well to the simulation ones. It indicates that the FEA model established is reasonable and reliable.

  7. Focusing properties of cylindrical vector vortex beams

    Science.gov (United States)

    Xiaoqiang, Zhang; Ruishan, Chen; Anting, Wang

    2018-05-01

    In this paper, following Richards and Wolf vectorial diffraction theory, the focusing properties of cylindrical vector vortex beams (CVVB) are investigated, and a diffractive optical element (DOE) is designed to spatially modulate the amplitude of the CVVB. Simulated results show that the CVVB focused by an objective also carry orbital angular momentum (OAM), and the optical fields near the focal region can be modulated by changing the topological charge of the CVVB. We numerically simulate the focus properties of radially and azimuthally polarized beams with topological charge equal to 0, 1, 2 and 10 respectively. As a result, a dark channel with a length about 20 λ can be obtained. These new properties have the potential applications such as particle acceleration, optical trapping and material processing.

  8. Indentation of Ellipsoidal and Cylindrical Elastic Shells

    KAUST Repository

    Vella, Dominic

    2012-10-01

    Thin shells are found in nature at scales ranging from viruses to hens\\' eggs; the stiffness of such shells is essential for their function. We present the results of numerical simulations and theoretical analyses for the indentation of ellipsoidal and cylindrical elastic shells, considering both pressurized and unpressurized shells. We provide a theoretical foundation for the experimental findings of Lazarus etal. [following paper, Phys. Rev. Lett. 109, 144301 (2012)PRLTAO0031-9007] and for previous work inferring the turgor pressure of bacteria from measurements of their indentation stiffness; we also identify a new regime at large indentation. We show that the indentation stiffness of convex shells is dominated by either the mean or Gaussian curvature of the shell depending on the pressurization and indentation depth. Our results reveal how geometry rules the rigidity of shells. © 2012 American Physical Society.

  9. Confined detonations with cylindrical and spherical symmetry

    International Nuclear Information System (INIS)

    Linan, A.; Lecuona, A.

    1979-01-01

    An imploding spherical or cylindrical detonation, starting in the interface of the detonantion with an external inert media, used as a reflector, creates on it a strong shock wave moving outward from the interface. An initially weak shock wave appears in the detonated media that travels toward the center, and it could reach the detonation wave, enforcing it in its process of implosion. To describe the fluid field, the Euler s equations are solved by means of expansions valid for the early stages of the process. Isentropic of the type P/pγ-K for the detonated and compressed inert media are used. For liquid or solid reflectors a more appropriate equation is used. (Author) 8 refs

  10. Unbalanced Cylindrical Magnetron for Accelerating Cavities Coating

    CERN Document Server

    Rosaz, Guillaume; Calatroni, Sergio; Sublet, Alban; Tobarelli, Mauro

    2016-01-01

    We report in this paper the design and qualification of a cylindrical unbalanced magnetron source. The dedicated magnetic assemblies were simulated using a finite element model. A hall-effect magnetic probe was then used to characterize those assemblies and compared to the theoretical magnet profiles. These show a good agreement between the expected and actual values. the qualification of the different magnetic assemblies was then performed by measuring the ion flux density reaching the surface of the sample to be coated using a commercial retarding field energy analyzer. The strongest unbalanced configuration shows an increase from 0.016A.cm^-2 to 0.074A.cm^-2 of the ion flux density reaching the sample surface compared to the standard balanced configuration for a pressure 5.10^-3 mbar and a plasma source power of 300W.

  11. Space charge emission in cylindrical diode

    International Nuclear Information System (INIS)

    Torres-Córdoba, Rafael; Martínez-García, Edgar

    2014-01-01

    In this paper, a mathematical model to describe cylindrical electron current emissions through a physics approximation method is presented. The proposed mathematical approximation consists of analyzing and solving the nonlinear Poisson's equation, with some determined mathematical restrictions. Our findings tackle the problem when charge-space creates potential barrier that disable the steady-state of the beam propagation. In this problem, the potential barrier effects of electron's speed with zero velocity emitted through the virtual cathode happens. The interaction between particles and the virtual cathode have been to find the inter-atomic potentials as boundary conditions from a quantum mechanics perspective. Furthermore, a non-stationary spatial solution of the electrical potential between anode and cathode is presented. The proposed solution is a 2D differential equation that was linearized from the generalized Poisson equation. A single condition was used solely, throughout the radial boundary conditions of the current density formation

  12. Analysis of a cylindrical imploding shock wave

    International Nuclear Information System (INIS)

    Mishkin, E.A.; Fujimoto, Y.

    1978-01-01

    the self-similar solution of the gasdynamic equations of a strong cylindrical shock wave moving through an ideal gas, with γ = csub(p)/csub(v), is considered. These equations are greatly simplified following the transformation of the reduced velocity U 1 (xi) → U 1 = 1/2(γ + 1 ) (U + xi). The requirement of a single maximum pressure, dsub(xi)P = 0, leads to an analytical determination of the self-similarity exponent α(γ). For gases with γ = 2 + 3sup(1/2), this maximum ensues right at the shock front and the pressure distribution then decreases monotonically. The postulate of analyticity by Gelfand and Butler is shown to concur with the requirement dsub(xi)P 0. The saturated density of the gas left in the wake of the shock is computed and - U is shown to be the reduced velocity of sound at P = P sub(m). (author)

  13. Cathode Effects in Cylindrical Hall Thrusters

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Solar heat gain through vertical cylindrical glass

    Energy Technology Data Exchange (ETDEWEB)

    Kassem, M.A.; Kaseb, S.; El-Refaie, M.F. [Cairo Univ., Mechanical Power Engineering Dept., Cairo (Egypt)

    1999-10-01

    Spaces with nonplanar glazed envelopes are frequently encountered in contemporary buildings. Such spaces represent a problem when calculating the solar heat gain in the course of estimating the cooling or heating load; and hence, sizing of cooling or heating systems. The calculation, using the information currently available in the literature, is tedious and/or approximate. In the present work, the computational procedure for evaluating the solar heat gain to a space having a vertical cylindrical glass envelope is established, and, a computer program is coded to carry out the necessary computations and yield the results in a detailed usable form. The program is versatile and allows for the arbitrary variation of all pertinent parameters. (Author)

  15. Solar heat gain through vertical cylindrical glass

    International Nuclear Information System (INIS)

    Kassem, M.A.; Kaseb, S.; El-Refaie, M.F.

    1999-01-01

    Spaces with nonplanar glazed envelopes are frequently encountered in contemporary buildings. Such spaces represent a problem when calculating the solar heat gain in the course of estimating the cooling or heating load; and hence, sizing of cooling or heating systems. The calculation, using the information currently available in the literature, is tedious and/or approximate. In the present work, the computational procedure for evaluating the solar heat gain to a space having a vertical cylindrical glass envelope is established, and, a computer program is coded to carry out the necessary computations and yield the results in a detailed usable form. The program is versatile and allows for the arbitrary variation of all pertinent parameters. (Author)

  16. Solar heat gain through vertical cylindrical glass

    Energy Technology Data Exchange (ETDEWEB)

    Kassem, M.A.; Kaseb, S.; El-Refaie, M.F. [Cairo Univ., Mechanical Power Engineering Dept., Cairo (Egypt)

    1999-07-01

    Spaces with nonplanar glazed envelopes are frequently encountered in contemporary buildings. Such spaces represent a problem when calculating the solar heat gain in the course of estimating the cooling or heating load; and hence, sizing of cooling or heating systems. The calculation, using the information currently available in the literature, is tedious and/or approximate. In the present work, the computational procedure for evaluating the solar heat gain to a space having a vertical cylindrical glass envelope is established, and, a computer program is coded to carry out the necessary computations and yield the results in a detailed usable form. The program is versatile and allows for the arbitrary variation of all pertinent parameters. (Author)

  17. Diffusion coefficient calculations for cylindrical cells

    International Nuclear Information System (INIS)

    Lam-Hime, M.

    1983-03-01

    An accurate and general diffusion coefficient calculation for cylindrical cells is described using isotropic scattering integral transport theory. This method has been particularly applied to large regular lattices of graphite-moderated reactors with annular coolant channels. The cells are divided into homogeneous zones, and a zone-wise flux expansion is used to formulate a collision probability problem. The reflection of neutrons at the cell boundary is accounted for by the conservation of the neutron momentum. The uncorrected diffusion coefficient Benoist's definition is used, and the described formulation does not neglect any effect. Angular correlation terms, energy coupling non-uniformity and anisotropy of the classical flux are exactly taken into account. Results for gas-graphite typical cells are given showing the importance of these approximations

  18. Study of Cylindrical Honeycomb Solar Collector

    Directory of Open Access Journals (Sweden)

    Atish Mozumder

    2014-01-01

    Full Text Available We present the results of our investigation on cylindrical honeycomb solar collector. The honeycomb has been fabricated with transparent cellulose triacetate polymer sheets. Insulation characteristics of the honeycomb were studied by varying the separation between the honeycomb and the absorber plate. The optimal value of the separation was found to be 3.3 mm for which the heat transfer coefficient is 3.06 W m−2 K−1. This supports result of previous similar experiments. Further we test the honeycomb through a field experiment conducted in Delhi (28.6°N, 77°E and found that when the incident angle of the solar radiation is within 20° then the performance of the system with the honeycomb is better than the one without the honeycomb.

  19. Bearing Fault Classification Based on Conditional Random Field

    Directory of Open Access Journals (Sweden)

    Guofeng Wang

    2013-01-01

    Full Text Available Condition monitoring of rolling element bearing is paramount for predicting the lifetime and performing effective maintenance of the mechanical equipment. To overcome the drawbacks of the hidden Markov model (HMM and improve the diagnosis accuracy, conditional random field (CRF model based classifier is proposed. In this model, the feature vectors sequences and the fault categories are linked by an undirected graphical model in which their relationship is represented by a global conditional probability distribution. In comparison with the HMM, the main advantage of the CRF model is that it can depict the temporal dynamic information between the observation sequences and state sequences without assuming the independence of the input feature vectors. Therefore, the interrelationship between the adjacent observation vectors can also be depicted and integrated into the model, which makes the classifier more robust and accurate than the HMM. To evaluate the effectiveness of the proposed method, four kinds of bearing vibration signals which correspond to normal, inner race pit, outer race pit and roller pit respectively are collected from the test rig. And the CRF and HMM models are built respectively to perform fault classification by taking the sub band energy features of wavelet packet decomposition (WPD as the observation sequences. Moreover, K-fold cross validation method is adopted to improve the evaluation accuracy of the classifier. The analysis and comparison under different fold times show that the accuracy rate of classification using the CRF model is higher than the HMM. This method brings some new lights on the accurate classification of the bearing faults.

  20. The magnetic properties of the hollow cylindrical ideal remanence magnet

    DEFF Research Database (Denmark)

    Bjørk, Rasmus

    2016-01-01

    We consider the magnetic properties of the hollow cylindrical ideal remanence magnet. This magnet is the cylindrical permanent magnet that generates a uniform field in the cylinder bore, using the least amount of magnetic energy to do so. The remanence distribution of this magnet is derived...

  1. Cylindrical and spherical dust-acoustic wave modulations in dusty ...

    Indian Academy of Sciences (India)

    Abstract. The nonlinear wave modulation of planar and non-planar (cylindrical and spherical) dust-acoustic waves (DAW) propagating in dusty plasmas, in the presence of non-extensive distribu- tions for ions and electrons is investigated. By employing multiple scales technique, a cylindrically and spherically modified ...

  2. Coupled dilaton and electromagnetic field in cylindrically symmetric ...

    Indian Academy of Sciences (India)

    The dilaton black hole solutions have attracted considerable attention for the ... theory and study the corresponding cylindrically symmetric spacetime, where .... where Йm and Йe are integration constants to be interpreted later as the ..... feature is apparent for the cylindrically symmetric spacetime in the presence of the dila-.

  3. Ingestion of six cylindrical and four button batteries

    DEFF Research Database (Denmark)

    Nielsen, Simon U; Rasmussen, Morten; Hoegberg, Lotte C G

    2010-01-01

    We report a suicidal ingestion of six cylindrical and four button batteries, in combination with overdosed prescription medicine and smoking of cannabis.......We report a suicidal ingestion of six cylindrical and four button batteries, in combination with overdosed prescription medicine and smoking of cannabis....

  4. Settling of a cylindrical particle in a stagnant fluid

    DEFF Research Database (Denmark)

    Sørensen, Henrik; Rosendahl, Lasse; Yin, Chungen

    The objective of this work is to collect data and develop models for cylindrical particles which could be used in numerical multiphase flow modeling. Trajectories of cylindrical particles settling in stagnant water are filmed from two directions in order to derive detailed information on their mo...

  5. Analysis of radial vibrations of poroelastic circular cylindrical shells ...

    African Journals Online (AJOL)

    DR OKE

    vanished, the considered problem reduces to the problem of radial vibrations of fluid-filled poroelastic circular cylindrical shell. (2). When the .... the volume change of the solid to that of liquid. ..... When the outer fluid density is zero, that is, ρof = 0 then the poroelastic cylindrical shell immersed in an acoustic medium will.

  6. Edge coating apparatus with movable roller applicator for solar cell substrates

    Science.gov (United States)

    Pavani, Luca; Abas, Emmanuel

    2012-12-04

    A non-contact edge coating apparatus includes an applicator for applying a coating material on an edge of a solar cell substrate and a control system configured to drive the applicator. The control system may drive the applicator along an axis to maintain a distance with an edge of the substrate as the substrate is rotated to have the edge coated with a coating material. The applicator may include a recessed portion into which the edge of the substrate is received for edge coating. For example, the applicator may be a roller with a groove. Coating material may be introduced into the groove for application onto the edge of the substrate. A variety of coating materials may be employed with the apparatus including hot melt ink and UV curable plating resist.

  7. Acute Lameness in a Roller Pigeon ( Columba livia ) with Multicentric Lymphosarcoma.

    Science.gov (United States)

    Williams, Susan M; Williams, Robert J; Gogal, Robert M

    2017-06-01

    A 3-yr-old adult female roller pigeon ( Columba livia ) used as part of a breeding pair for an ongoing research study presented with acute left limb lameness. Palpation of the left leg and region revealed a large lump near the coxofemoral joint. The bird was able to ambulate in the cage, but would not brood her hatchling. The bird was humanely euthanized and necropsy was performed. Grossly, multiple large white to pale tan nodules were noted in the pancreas, lung, rib cage, intestines, and unilaterally in the left kidney. Microscopic examination of the various organs revealed neoplastic proliferation of round cells consistent with lymphoblasts. Immunohistochemistry was performed with the use of antibodies to CD3, CD79a, CD20, and CD21 to phenotype the cells. The results indicated that the neoplastic infiltrating cells were predominantly of T-cell origin.

  8. The effects of poling on physiological, kinematic and kinetic responses in roller ski skating.

    Science.gov (United States)

    Grasaas, Erik; Hegge, Ann Magdalen; Ettema, Gertjan; Sandbakk, Øyvind

    2014-09-01

    We investigated the effects of poling on physiological, kinematic and kinetic responses in the G4 skating technique where the poling movement is synchronized with the leg push-off on one side (strong side) followed by a forward arm swing during the leg push-off on the other side (weak side). G4 skating with (G4-P) and without (G4-NP) poling was compared in 17 elite male cross-country skiers during 4-min submaximal tests on a 2% inclined roller ski treadmill at 10, 15 and 20 km h(-1). G4-P demonstrated less ventilatory stress and higher gross efficiency compared to G4-NP at all velocities, and the blood lactate concentration was lower at the high velocity (all P skating technique. Thus, poling provides possibilities to increase total propulsion, to reduce ski forces and to enhance skiing efficiency.

  9. The effects of the arm swing on biomechanical and physiological aspects of roller ski skating.

    Science.gov (United States)

    Hegge, Ann Magdalen; Ettema, Gertjan; de Koning, Jos J; Rognstad, Asgeir Bakken; Hoset, Martin; Sandbakk, Øyvind

    2014-08-01

    This study analyzed the biomechanical and physiological effects of the arm swing in roller ski skating, and compared leg-skating (i.e. ski skating without poles) using a pronounced arm swing (SWING) with leg-skating using locked arms (LOCKED). Sixteen elite male cross-country skiers performed submaximal stages at 10, 15 and 20kmh(-1) on a 2% inclined treadmill in the two techniques. SWING demonstrated higher peak push-off forces and a higher force impulse at all speeds, but a longer cycle length only at the highest speed (all Pskating increases the ski forces and aerobic energy cost at low and moderate speeds, whereas the greater forces at high speed lead to a longer cycle length and smaller anaerobic contribution. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Failure of the chassis of roller skates for agonistic figure skating

    Directory of Open Access Journals (Sweden)

    Giorgio Olmi

    2015-04-01

    Full Text Available The subject of this work was to investigate the early failure, which occurred in the chassis of a roller skate for figure skating. The paper deals with the preliminary analysis of the crack and with the integrated approach, which had to be followed to overcome the problem. Literature in the fields of physiology and biomechanics was studied to correctly simulate the load distribution on the chassis. Finite element simulation, experimental stress analysis and analytical modeling of impact phenomena had to be combined together to estimate the entity of dynamic loads and the corresponding state of stress. The analysis led to the determination of the primary cause of failure, bending fatigue, and to the suggestion of a simple solution to improve and optimize the project.

  11. Hot roller embossing system equipped with a temperature margin-based controller

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seyoung, E-mail: seyoungkim@kimm.re.kr; Son, Youngsu; Lee, Sunghee; Ham, Sangyong; Kim, Byungin [Department of Robotics and Mechatronics, Korea Institute of Machinery and Materials (KIMM), Daejeon (Korea, Republic of)

    2014-08-15

    A temperature control system was proposed for hot roller embossing. The roll surface was heated using induction coils and cooled with a circulating chilled water system. The temperature of the roll surface was precisely controlled by a temperature margin-based control algorithm that we developed. Implementation of the control system reduced deviations in the roll surface temperature to less than ±2 °C. The tight temperature control and the ability to rapidly increase and decrease the roll temperature will allow optimum operating parameters to be developed quickly. The temperature margin-based controller could also be used to optimize the time course of electrical power and shorten the cooling time by choosing an appropriate temperature margin, possibly for limited power consumption. The chiller-equipped heating roll with the proposed control algorithm is expected to decrease the time needed to determine the optimal embossing process.

  12. Field Assessment and Specification Review for Roller-Integrated Compaction Monitoring Technologies

    Directory of Open Access Journals (Sweden)

    David J. White

    2011-01-01

    Full Text Available Roller-integrated compaction monitoring (RICM technologies provide virtually 100-percent coverage of compacted areas with real-time display of the compaction measurement values. Although a few countries have developed quality control (QC and quality assurance (QA specifications, broader implementation of these technologies into earthwork construction operations still requires a thorough understanding of relationships between RICM values and traditional in situ point test measurements. The purpose of this paper is to provide: (a an overview of two technologies, namely, compaction meter value (CMV and machine drive power (MDP; (b a comprehensive review of field assessment studies, (c an overview of factors influencing statistical correlations, (d modeling for visualization and characterization of spatial nonuniformity; and (e a brief review of the current specifications.

  13. New roller cone bits with unique nozzle designs reduce drilling costs

    International Nuclear Information System (INIS)

    Moffitt, S.R.; Pearce, D.E.; Ivie, C.R.

    1992-01-01

    This paper reports that selection of the optimum rock bit design to achieve the lowest drilling cost in a given application is often difficult due to a large number of rock bit performance considerations. However, in a majority of applications increased penetration rate is the key consideration in reducing drilling costs. Discovery of a new bit design concept has led to the development of roller cone bits that achieve significant penetration rate increases using superior hydraulic nozzle designs. Prototype designs have achieved 20 to 40% increases in penetration rate with comparable footage drilled when tested in 6 1/2, 8 1/2, 8-3/4, 9-7/8 and 12 1/4 IADC 437, 517 and 537 type bits in the U.S., North Sea, Italy, and Oman. Second-generation designs tested in a full-scale drilling laboratory have delivered 70% increases in penetration rates

  14. The effects of adding waste plastic fibers on some properties of roller compacted concrete

    Directory of Open Access Journals (Sweden)

    Abed Adil

    2018-01-01

    Full Text Available An attempt to produce of roller compacted concrete (RCC improved by adding waste plastic fibers (WPFs resulting from cutting the PET beverage bottles was recorded in this study. The method which is used for production of RCC is an approved design method for ACI committee (5R-207,1980[1]. WPF was added by volumetric percentages ranging between (0.5 to 2 % and reference concrete mix was produced for comparison reason. Many tests were conducted on the models produced by rolling compacted concrete like compressive strength, flexural strength, modulus of elasticity, dry density, water absorption and ultrasonic pulse velocity. The analysis of the results showed that the use of plastic waste fibers (1% had led to improvement in the properties of each of the compressive strength and flexural strength compared with reference concrete. Results also showed that the addition of these, fibers increase water absorption and reduce the speed of Ultrasonic pulse velocity.

  15. The physiological and biomechanical contributions of poling to roller ski skating.

    Science.gov (United States)

    Sandbakk, Øyvind; Ettema, Gertjan; Holmberg, Hans-Christer

    2013-08-01

    Poling is considered to make a significant contribution to cross-country skiing with the skating technique. To better understand this contribution, the current investigation compared roller ski skating on a treadmill with the so-called G3 skating technique with (G3-P) and without poling (G3-NP). Seven male elite skiers performed 5-min submaximal tests at 8, 12, and 15 km h(-1), as well as an incremental test to exhaustion with both techniques on a 5 % incline. Ventilatory variables were assessed by open-circuit indirect calorimetry and three-dimensional kinematics analyzed using the Qualisys Pro Reflex system. G3-P was associated with approximately 15 % higher peak velocity and 10 % higher peak oxygen uptake than G3-NP in the incremental test (both P skating, specifically by enhancing peak oxygen uptake, skiing efficiency and associated biomechanical variables.

  16. Kinematic and dynamic modeling and approximate analysis of a roller chain drive

    DEFF Research Database (Denmark)

    Fuglede, Niels; Thomsen, Jon Juel

    2016-01-01

    for analytical studies of the coupled motion of the chain spans and driven sprocket. Parametric excitation of the spans come from sprocket angular displacements, and the driven sprocket acts as a boundary which can be compliant in the axial direction. External transverse excitation of the spans comes from...... polygonal action, and is treated through kinematic forcing at the moving string boundaries. Perturbation analysis of the model is carried out using the method of multiple scales. Results show a multitude of internal and external resonance conditions, and some examples are presented of both decoupled...... and coupled motion. Together, the kinematic and dynamic model are aimed toward providing a framework for conducting and understanding both numerical, and experimental investigations of roller chain drive dynamics....

  17. A G-function-based reliability-based design methodology applied to a cam roller system

    International Nuclear Information System (INIS)

    Wang, W.; Sui, P.; Wu, Y.T.

    1996-01-01

    Conventional reliability-based design optimization methods treats the reliability function as an ordinary function and applies existing mathematical programming techniques to solve the design problem. As a result, the conventional approach requires nested loops with respect to g-function, and is very time consuming. A new reliability-based design method is proposed in this paper that deals with the g-function directly instead of the reliability function. This approach has the potential of significantly reducing the number of calls for g-function calculations since it requires only one full reliability analysis in a design iteration. A cam roller system in a typical high pressure fuel injection diesel engine is designed using both the proposed and the conventional approach. The proposed method is much more efficient for this application

  18. Hot roller embossing system equipped with a temperature margin-based controller

    International Nuclear Information System (INIS)

    Kim, Seyoung; Son, Youngsu; Lee, Sunghee; Ham, Sangyong; Kim, Byungin

    2014-01-01

    A temperature control system was proposed for hot roller embossing. The roll surface was heated using induction coils and cooled with a circulating chilled water system. The temperature of the roll surface was precisely controlled by a temperature margin-based control algorithm that we developed. Implementation of the control system reduced deviations in the roll surface temperature to less than ±2 °C. The tight temperature control and the ability to rapidly increase and decrease the roll temperature will allow optimum operating parameters to be developed quickly. The temperature margin-based controller could also be used to optimize the time course of electrical power and shorten the cooling time by choosing an appropriate temperature margin, possibly for limited power consumption. The chiller-equipped heating roll with the proposed control algorithm is expected to decrease the time needed to determine the optimal embossing process

  19. Multivariable H force/level control of the twin-roller strip caster

    International Nuclear Information System (INIS)

    Cavazos, A.; Edwards, J.B.

    2005-01-01

    Twin-roller steel strip casters may offer some advantages with respect to classical continuous casting hot rolling processes. Some works have reported control aspects of this process and although the process has been found to be highly interactive and non-linear, little or no attention has been given to its multivariable characteristics. The purpose of this work is to design a multivariable control capable of decoupling the system. This paper presents some important aspects of the strip caster modeling and reports the simulation results of the application of the multivariable H-optimal control for nominal performance to force/level control. Various controllers have been designed for different pool level heights and it is shown that they can decouple the system, allowing the application of PI decentralized controllers to considerably improve performance. (author)

  20. Magnetically leviated superconducting bearing

    Science.gov (United States)

    Weinberger, Bernard R.; Lynds, Jr., Lahmer

    1993-01-01

    A magnetically levitated superconducting bearing includes a magnet (2) mounted on a shaft (12) that is rotatable around an axis of rotation and a Type II superconductor (6) supported on a stator (14) in proximity to the magnet (2). The superconductor (6) is positioned so that when it is cooled to its superconducting state in the presence of a magnetic field, it interacts with the magnet (2) to produce an attractive force that levitates the magnet (2) and supports a load on the shaft (12). The interaction between the superconductor (6) and magnet(2) also produces surface screening currents (8) that generate a repulsive force perpendicular to the load. The bearing also has means for maintaining the superconductor at a temperature below its critical temperature (16, 18). The bearing could also be constructed so the magnet (2) is supported on the stator (14) and the superconductor (6) is mounted on the shaft (12). The bearing can be operated by cooling the superconductor (6) to its superconducting state in the presence of a magnetic field.

  1. Fast calculation method for computer-generated cylindrical holograms.

    Science.gov (United States)

    Yamaguchi, Takeshi; Fujii, Tomohiko; Yoshikawa, Hiroshi

    2008-07-01

    Since a general flat hologram has a limited viewable area, we usually cannot see the other side of a reconstructed object. There are some holograms that can solve this problem. A cylindrical hologram is well known to be viewable in 360 deg. Most cylindrical holograms are optical holograms, but there are few reports of computer-generated cylindrical holograms. The lack of computer-generated cylindrical holograms is because the spatial resolution of output devices is not great enough; therefore, we have to make a large hologram or use a small object to fulfill the sampling theorem. In addition, in calculating the large fringe, the calculation amount increases in proportion to the hologram size. Therefore, we propose what we believe to be a new calculation method for fast calculation. Then, we print these fringes with our prototype fringe printer. As a result, we obtain a good reconstructed image from a computer-generated cylindrical hologram.

  2. Disentangling migratory routes and wintering grounds of Iberian near-threatened European Rollers Coracias garrulus.

    Directory of Open Access Journals (Sweden)

    Juan Rodríguez-Ruiz

    Full Text Available Long-distance migrants are suffering drastic declines in the last decades. Causes beneath this problem are complex due to the wide spatial and temporal scale involved. We aim to reveal migratory routes, stopover areas, wintering grounds, and migratory strategies for the most southwestern populations of the near-threatened European Roller Coracias garrulus in order to identify conservation key areas for the non-breeding stage of this species. To this end, we used tracking data from seven satellite transmitters fitted to birds breeding in different populations throughout the Iberian Peninsula and four geolocators fitted to individuals in a southeastern Iberian population. Precise satellite data were used to describe daily activity patterns and speed in relation to the main regions crossed during the migration. Individuals from the most southwestern Iberian populations made a detour towards the Atlantic African coast whereas those from northeastern populations followed a straight north-to-south route. We identified important stopover areas in the Sahel belt, mainly in the surroundings of the Lake Chad, and wintering grounds on southwestern Africa farther west than previously reported for the species. Concerning the migratory strategy, satellite data revealed: 1 a mainly nocturnal flying activity, 2 that migration speed depended on the type of crossed habitat, with higher average speed while crossing the desert; and 3 that the migration was slower and lasted longer in autumn than in spring. The studied populations showed weak migratory connectivity, suggesting the confluence of birds from a wide range of breeding grounds in a restricted wintering area. Therefore, we suggest to target on defining precisely key areas for this species and identifying specific threats in them in order to develop an appropriate global conservation programme for the European Roller.

  3. Quantitative evaluation of hand cranking a roller pump in a crisis management drill.

    Science.gov (United States)

    Tomizawa, Yasuko; Tokumine, Asako; Ninomiya, Shinji; Momose, Naoki; Matayoshi, Toru

    2008-01-01

    The heart-lung machines for open-heart surgery have improved over the past 50 years; they rarely break down and are almost always equipped with backup batteries. The hand-cranking procedure only becomes necessary when a pump breaks down during perfusion or after the batteries have run out. In this study, the performance of hand cranking a roller pump was quantitatively assessed by an objective method using the ECCSIM-Lite educational simulator system. A roller pump connected to an extracorporeal circuit with an oxygenator and with gravity venous drainage was used. A flow sensor unit consisting of electromagnetic sensors was used to measure arterial and venous flow rates, and a built-in pressure sensor was used to measure the water level in the reservoir. A preliminary study of continuous cranking by a team of six people was conducted as a surprise drill. This system was then used at a perfusion seminar. At the seminar, 1-min hand-cranking drills were conducted by volunteers according to a prepared scenario. The data were calculated on site and trend graphs of individual performances were given to the participants as a handout. Preliminary studies showed that each person's performance was different. Results from 1-min drills showed that good performance was not related to the number of clinical cases experienced, years of practice, or experience in hand cranking. Hand cranking to maintain the target flow rate could be achieved without practice; however, manipulating the venous return clamp requires practice. While the necessity of performing hand cranking during perfusion due to pump failure is rare, we believe that it is beneficial for perfusionists and patients to include hand-cranking practice in periodic extracorporeal circulation crisis management drills because a drill allows perfusionists to mentally rehearse the procedures should such a crisis occur.

  4. Roller compaction: Effect of morphology and amorphous content of lactose powder on product quality.

    Science.gov (United States)

    Omar, Chalak S; Dhenge, Ranjit M; Osborne, James D; Althaus, Tim O; Palzer, Stefan; Hounslow, Michael J; Salman, Agba D

    2015-12-30

    The effect of morphology and amorphous content, of three types of lactose, on the properties of ribbon produced using roller compaction was investigated. The three types of lactose powders were; anhydrous SuperTab21AN, α-lactose monohydrate 200 M, and spray dried lactose SuperTab11SD. The morphology of the primary particles was identified using scanning electron microscopy (SEM) and the powder amorphous content was quantified using NIR technique. SEM images showed that 21AN and SD are agglomerated type of lactose whereas the 200 M is a non-agglomerated type. During ribbon production, an online thermal imaging technique was used to monitor the surface temperature of the ribbon. It was found that the morphology and the amorphous content of lactose powders have significant effects on the roller compaction behaviour and on ribbon properties. The agglomerated types of lactose produced ribbon with higher surface temperature and tensile strength, larger fragment size, lower porosity and lesser fines percentages than the non-agglomerated type of lactose. The lactose powder with the highest amorphous content showed to result in a better binding ability between the primary particles. This type of lactose produced ribbons with the highest temperature and tensile strength, and the lowest porosity and amount of fines in the product. It also produced ribbon with more smooth surfaces in comparison to the other two types of lactose. It was noticed that there is a relationship between the surface temperature of the ribbon during production and the tensile strength of the ribbon; the higher the temperature of the ribbon during production the higher the tensile strength of the ribbon. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Converging cylindrical shocks in ideal magnetohydrodynamics

    International Nuclear Information System (INIS)

    Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.

    2014-01-01

    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=√(μ 0 /p 0 ) I/(2 π) where I is the current, μ 0 is the permeability, and p 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 diverging magnetic field

  6. Converging cylindrical shocks in ideal magnetohydrodynamics

    KAUST Repository

    Pullin, D. I.

    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 = √μ0/p0 I/(2π) 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 then

  7. Converging cylindrical shocks in ideal magnetohydrodynamics

    KAUST Repository

    Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, Ravi

    2014-01-01

    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 = √μ0/p0 I/(2π) 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 then

  8. Converging cylindrical shocks in ideal magnetohydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Pullin, D. I. [Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, California 91125 (United States); Mostert, W.; Wheatley, V. [School of Mechanical and Mining Engineering, University of Queensland, Queensland 4072 (Australia); Samtaney, R. [Mechanical Engineering, Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia)

    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

  9. Actuators for Active Magnetic Bearings

    Directory of Open Access Journals (Sweden)

    Eric H. Maslen

    2017-10-01

    Full Text Available The literature of active magnetic bearing (AMB technology dates back to at least 1937 when the earliest work that clearly describes an active magnetic bearing system was published by Jesse Beams [...

  10. A General Case to Determine Dimensions and Their Tolerance Zones for the Thread Parts of Epicyclic Roller-Screw Mechanisms

    Directory of Open Access Journals (Sweden)

    D. S. Blinov

    2017-01-01

    Full Text Available The most important trend in the development of aerospace industry is to increase load capacity of mechanisms, assemblies, and parts without increasing their size and weight. The above is also true for widely used in aircrafts and the most promising up to date Epicyclic Roller-Screw Mechanisms (ERSM that convert rotational movement into translational one. Previously (in the article, it was proposed to increase the load capacity (approximately by 15% through reduction of included angle of ERSM threaded parts from 90° to 70°.However, such improvement of ERSM will change dimensions of the mechanism parts and its parameters and characteristics (efficiency factor, position of initial point of contact of the conjugated thread turns and parameters of their contact interaction, as well as kinematic parameters, which will require additional studies. If we take into account the priority of these studies, then surely we must begin with development of technique to determine dimensions of the ERSM main parts and their tolerance zones because we need drawings to manufacture and test the upgraded ERSM. We have developed a technique to calculate dimensions of the main parts of ERSM and associated tolerance zones that takes in to account the change of included angle of threaded parts of the mechanism and radius of circular arc according to which roller thread profile has been fulfilled. So the proposed technique is the general one in comparison with the previous ones.This technique uses various conditions and equations to determine dimensions of parts and associated tolerance zones. For example, a nut encircles a screw with rollers, and their dimensions form a closed dimension chain, in which the dimensions and associated tolerances must be such as to ensure ERSM assembling, on the one hand, and, on the other hand the backlash of the mechanism should be minimal to ensure high load capacity, kinematic accuracy, and rigidity of ERSM. We used the following

  11. Arbitrarily elliptical-cylindrical invisible cloaking

    International Nuclear Information System (INIS)

    Jiang Weixiang; Cui Tiejun; Yu Guanxia; Lin Xianqi; Cheng Qiang; Chin, J Y

    2008-01-01

    Based on the idea of coordinate transformation (Pendry, Schurig and Smith 2006 Science 312 1780), arbitrarily elliptical-cylindrical cloaks are proposed and designed. The elliptical cloak, which is composed of inhomogeneous anisotropic metamaterials in an elliptical-shell region, will deflect incoming electromagnetic (EM) waves and guide them to propagate around the inner elliptical region. Such EM waves will return to their original propagation directions without distorting the waves outside the elliptical cloak. General formulations of the inhomogeneous and anisotropic permittivity and permeability tensors are derived for arbitrarily elliptical axis ratio k, which can also be used for the circular cloak when k = 1. Hence the elliptical cloaks can make a large range of objects invisible, from round objects (when k approaches 1) to long and thin objects (when k is either very large or very small). We also show that the material parameters in elliptical cloaking are singular at only two points, instead of on the whole inner circle for circular cloaking, which are much easier to be realized in actual applications. Full-wave simulations are given to validate the arbitrarily elliptical cloaking

  12. Electrical tensor Green functions for cylindrical waveguides

    International Nuclear Information System (INIS)

    Prijmenko, S.D.; Papkovich, V.G.; Khizhnyak, N.A.

    1988-01-01

    Formation of electrical tensor Green functions for cylindrical waveguides is considered. Behaviour of these functions in the source region is studied. Cases of electrical tensor Green functions for vector potential G E (r-vector, r'-vector) and electric field G e (r-vector, r'-vector) are analysed. When forming G E (r-vector, r'-vector), its dependence on lateral coordinates is taken into account by means of two-dimensional fundamental vector Hansen functions, several methods are used to take into account the dependence on transverse coordinate. When forming G e (r-vector, r'-vector) we use the fact that G E (r-vector, r'-vector) and G e (r-vector, r'-vector) are the generalized functions. It is shown that G e (r-vector, r'-vector) behaviour in the source region is defined by a singular term, which properties are described by the delta-function. Two variants of solving the problem of defining singular and regular sides of tensor function G E (r-vector, r'-vector) are presented. 23 refs

  13. Cylindrical Hall Thrusters with Permanent Magnets

    International Nuclear Information System (INIS)

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

    2010-01-01

    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.

  14. Electron emitter pulsed-type cylindrical IEC

    International Nuclear Information System (INIS)

    Miley, G.H.; Gu, Y.; Stubbers, R.; Zich, R.; Anderl, R.; Hartwell, J.

    1997-01-01

    A cylindrical version of the single grid Inertial Electrostatic Confinement (IEC) device (termed the C-device) has been developed for use as a 2.5-MeV D-D fusion neutron source for neutron activation analysis. The C-device employs a hollow-tube type cathode with similar anodes backed up by ''reflector'' dishes. The resulting discharge differs from a conventional hollow cathode discharge, by creating an explicit ion beam which is ''pinched'' in the cathode region. Resulting fusion reactions generate ∼10 6 neutron/s. A pulsed version is under development for applications requiring higher fluxes. Several pulsing techniques are under study, including an electron emitter (e-emitter) assisted discharge in a thorated tungsten wire emitter located behind a slotted area in the reflector dishes. Pulsing is initiated after establishing a low power steady-state discharge by pulsing the e-emitter current using a capacitor switch type circuit. The resulting electron jet, coupled with the discharge by the biased slot array, creates a strong pulse in the pinched ion beam. The pulse length/repetition rate are controlled by the e-emitter pulse circuit. Typical parameters in present studies are ∼30micros, 10Hz and 1-amp ion current. Corresponding neutron measurements are an In-foil type activation counter for time averaged rates. Results for a wide variety of operating conditions are presented

  15. Parametric Investigation of Miniaturized Cylindrical and Annular Hall Thrusters

    International Nuclear Information System (INIS)

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

    2002-01-01

    Conventional annular Hall thrusters become inefficient when scaled to low power. An alternative approach, a 2.6-cm miniaturized cylindrical Hall thruster with a cusp-type magnetic field distribution, was developed and studied. Its performance was compared to that of a conventional annular thruster of the same dimensions. The cylindrical thruster exhibits discharge characteristics similar to those of the annular thruster, but it has a much higher propellant ionization efficiency. Significantly, a large fraction of multi-charged xenon ions might be present in the outgoing ion flux generated by the cylindrical thruster. The operation of the cylindrical thruster is quieter than that of the annular thruster. The characteristic peak in the discharge current fluctuation spectrum at 50-60 kHz appears to be due to ionization instabilities. In the power range 50-300 W, the cylindrical and annular thrusters have comparable efficiencies (15-32%) and thrusts (2.5-12 mN). For the annular configuration, a voltage less than 200 V was not sufficient to sustain the discharge at low propellant flow rates. The cylindrical thruster can operate at voltages lower than 200 V, which suggests that a cylindrical thruster can be designed to operate at even smaller power

  16. Delayed child-bearing.

    Science.gov (United States)

    Johnson, Jo-Ann; Tough, Suzanne

    2012-01-01

    To provide an overview of delayed child-bearing and to describe the implications for women and health care providers. Delayed child-bearing, which has increased greatly in recent decades, is associated with an increased risk of infertility, pregnancy complications, and adverse pregnancy outcome. This guideline provides information that will optimize the counselling and care of Canadian women with respect to their reproductive choices. Maternal age is the most important determinant of fertility, and obstetric and perinatal risks increase with maternal age. Many women are unaware of the success rates or limitations of assisted reproductive technology and of the increased medical risks of delayed child-bearing, including multiple births, preterm delivery, stillbirth, and Caesarean section. This guideline provides a framework to address these issues. Studies published between 2000 and August 2010 were retrieved through searches of PubMed and the Cochrane Library using appropriate key words (delayed child-bearing, deferred pregnancy, maternal age, assisted reproductive technology, infertility, and multiple births) and MeSH terms (maternal age, reproductive behaviour, fertility). The Internet was also searched using similar key words, and national and international medical specialty societies were searched for clinical practice guidelines and position statements. Data were extracted based on the aims, sample, authors, year, and results. The quality of evidence was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table 1). The Society of Obstetricians and Gynaecologists of Canada. RECOMMENDATIONS 1. Women who delay child-bearing are at increased risk of infertility. Prospective parents, especially women, should know that their fecundity and fertility begin to decline significantly after 32 years of age. Prospective parents should know that assisted reproductive technologies cannot guarantee a live birth or completely

  17. Government Risk-Bearing

    CERN Document Server

    1993-01-01

    The u.s. government bulks large in the nation's financial markets. The huge volume of government-issued and -sponsored debt affects the pricing and volume ofprivate debt and, consequently, resource allocation between competing alternatives. What is often not fully appreciated is the substantial influence the federal government wields overresource allocation through its provisionofcreditandrisk-bearing services to the private economy. Because peopleand firms generally seekto avoid risk, atsomeprice they are willing to pay another party to assume the risk they would otherwise face. Insurance companies are a class of private-sector firms one commonly thinks of as providing these services. As the federal government has expanded its presence in the U.S. economy during this century, it has increasingly developed programs aimed at bearing risks that the private sector either would not take on at any price, or would take on but atapricethoughtto besogreatthatmostpotentialbeneficiarieswouldnotpurchase the coverage. To...

  18. Stacked magnet superconducting bearing

    International Nuclear Information System (INIS)

    Rigney, T.K. II; Saville, M.P.

    1993-01-01

    A superconducting bearing is described, comprising: a plurality of permanent magnets magnetized end-to-end and stacked side-by-side in alternating polarity, such that flux lines flow between ends of adjacent magnets; isolating means, disposed between said adjacent magnets, for reducing flux leakage between opposing sides of said adjacent magnets; and a member made of superconducting material having at least one surface in communication with said flux lines

  19. Radium bearing waste disposal

    International Nuclear Information System (INIS)

    Tope, W.G.; Nixon, D.A.; Smith, M.L.; Stone, T.J.; Vogel, R.A.; Schofield, W.D.

    1995-01-01

    Fernald radium bearing ore residue waste, stored within Silos 1 and 2 (K-65) and Silo 3, will be vitrified for disposal at the Nevada Test Site (NTS). A comprehensive, parametric evaluation of waste form, packaging, and transportation alternatives was completed to identify the most cost-effective approach. The impacts of waste loading, waste form, regulatory requirements, NTS waste acceptance criteria, as-low-as-reasonably-achievable principles, and material handling costs were factored into the recommended approach

  20. Magnetic translator bearings

    Science.gov (United States)

    Hockney, Richard L. (Inventor); Downer, James R. (Inventor); Eisenhaure, David B. (Inventor); Hawkey, Timothy J. (Inventor); Johnson, Bruce G. (Inventor)

    1990-01-01

    A magnetic bearing system for enabling translational motion includes a carriage and a shaft for movably supporting the carriage; a first magnetic bearing fixed to one of the carriage and shaft and slidably received in a first channel of the other of the carriage and shaft. The first channel is generally U shaped with two side walls and a back wall. The magnetic bearing includes a pair of spaced magnetic pole pieces, each pole piece having a pair of electromagnetic coils mounted on poles on opposite ends of the pole piece proximate the side walls, and a third electromagnetic coil mounted on a pole of the pole piece proximate the backwall; a motion sensor for sensing translational motion along two axes and rotationally about three axes of the carriage and shaft relative to each other; and a correction circuit responsive to the sensor for generating a correction signal to drive the coils to compensate for any misalignment sensed between the carriage and the shaft.

  1. Cylindrical solitons in shallow water of variable depth

    International Nuclear Information System (INIS)

    Carbonaro, P.; Floris, R.; Pantano, P.

    1983-01-01

    The propagation and the interaction of cylindrical solitons in shallow water of variable depth are studied. Starting from the cylindrically symmetric version of the equations describing long waves in a beach, a Korteweg-de Vries equation is derived. Since no exact analytical solution has been found to date for this equation, some remarkable cases in which the equation takes up a tractable form are analyzed. Finally the intercation between cylindrical imploding and expanding waves is considered and the phase shifts caused by the head-on collision are given

  2. Vibrational analysis of submerged cylindrical shells based on elastic foundations

    International Nuclear Information System (INIS)

    Shah, A.G.; Naeem, M.N.

    2014-01-01

    In this study a vibration analysis was performed of an isotropic cylindrical shell submerged in fluid, resting on Winkler and Pasternak elastic foundations for simply supported boundary condition. Love's thin shell theory was exploited for strain- and curvature- displacement relationship. Shell problem was solved by using wave propagation approach. Influence of fluid and Winkler as well as Pasternak elastic foundations were studied on the natural frequencies of submerged isotropic cylindrical shells. Results were validated by comparing with the existing results in literature. Vibration, Submerged cylindrical shell, Love's thin shell theory, Wave propagation method, Winkler and Pasternak foundations. (author)

  3. The selection of flying roller as an effort to increase the power of scooter-matic as the main power of centrifugal pump for fire fighter motor cycle

    Science.gov (United States)

    Hadi Sutrisno, Himawan

    2018-03-01

    In densely populated settlements, fires often occur and cause losses. In some instances, the process of the occurrence of fires takes place so quickly that to reduce and avoid the occurrence of a fire disaster effort is required in accordance with the existing environmental condition. Fire fighter motorcycle by using motorcycle scooter-matic is considered suitable as one alternative to combating fire hazard in densely populated residential settlements. The use of motorcycle engines as the driving force of the pump often leads to unstable and not optimum power. Thus, the water spray on the centrifugal pump also becomes not maximum. To increase the engine power at scooter-matic engine idle rotation (700-2000 rpm), then the flying roller replacement with certain mass weight becomes an option. By selecting a 10 to 14 gram flying roller mass, the power analysis using a dynotest engine produces several variations. Of the calculation, the mass of a 14 gram flying roller provides a significant increase in motor power on the upper rotation. Meanwhile, on the lower power rotation using a flying roller with a mass of 10 grams provides an increase in power compared to a standard flying roller on a scooter matic motor engine. As a reference to the use of scooter-matic motor power as the pump power, the result of use of the flying roller with a mass of 10 grams becomes the best option.

  4. Bearing for liquid metal pump

    International Nuclear Information System (INIS)

    Dickinson, R.J.; Pennell, W.E.; Wasko, J.

    1984-01-01

    A liquid metal pump bearing support comprises a series of tangentially oriented spokes that connect the bearing cylinder to the pump internals structure. The spokes may be arranged in a plurality of planes extending from the bearing cylinder to the pump internals with the spokes in one plane being arranged alternately with those in the next plane. The bearing support structure provides the pump with sufficient lateral support for the bearing structure together with the capability of accommodating differential thermal expansion without adversely affecting pump performance

  5. Analysis of the Impacts of Bearing on Vibration Characteristics of Rotor

    Directory of Open Access Journals (Sweden)

    Peiji Yang

    2017-01-01

    Full Text Available Aiming at a Top Gas Recovery Turbine Unit (TRT with double support rotor and the extending disk end, theoretical and experimental analysis about influence of cylindrical bearing and four-lobe bearing on vibration of TRT rotor system are conducted in this paper. The results indicate that vibration of the rotor supported by cylindrical bearing is more stable than that supported by four-lobe bearing at the driving end (DE and the nondriving end (NDE. The amplitude of rotor is supported by both of these types of bearing increases as the speed increases at the NDE, while the amplitude of the DE remains unchanged. Comparing with the result of theoretical analysis, the practical test results are more consistent with the theoretical response analysis conducted by applying unbalanced mass at the extending disk end. This paper presents an analysis method of the critical characteristics of a double support rotor system with the extending disk end and provides reference value for dealing with vibration fault of double support rotor system with the extending disk end.

  6. External Cylindrical Nozzle with Controlled Vacuum

    Directory of Open Access Journals (Sweden)

    V. N. Pil'gunov

    2015-01-01

    Full Text Available There is a developed design of the external cylindrical nozzle with a vacuum camera. The paper studies the nozzle controllability of flow rate via regulated connection of the evacuated chamber to the atmosphere through an air throttle. Working capacity of the nozzle with inlet round or triangular orifice are researched. The gap is provided in the nozzle design between the external wall of the inlet orifice and the end face of the straight case in the nozzle case. The presented mathematical model of the nozzle with the evacuated chamber allows us to estimate the expected vacuum amount in the compressed section of a stream and maximum permissible absolute pressure at the inlet orifice. The paper gives experimental characteristics of the fluid flow process through the nozzle for different values of internal diameter of a straight case and an extent of its end face remoteness from an external wall of the inlet orifice. It estimates how geometry of nozzle constructive elements influences on the volume flow rate. It is established that the nozzle capacity significantly depends on the shape of inlet orifice. Triangular orifice nozzles steadily work in the mode of completely filled flow area of the straight case at much more amounts of the limit pressure of the flow. Vacuum depth in the evacuated chamber also depends on the shape of inlet orifice: the greatest vacuum is reached in a nozzle with the triangular orifice which 1.5 times exceeds the greatest vacuum with the round orifice. Possibility to control nozzle capacity through the regulated connection of the evacuated chamber to the atmosphere was experimentally estimated, thus depth of flow rate regulation of the nozzle with a triangular orifice was 45% in comparison with 10% regulation depth of the nozzle with a round orifice. Depth of regulation calculated by a mathematical model appeared to be much more. The paper presents experimental dependences of the flow coefficients of nozzle input orifice

  7. Experimental studies in Ultrasonic Pulse Velocity of roller compacted concrete pavement containing fly ash and M-sand

    Directory of Open Access Journals (Sweden)

    S. Krishna Rao

    2016-07-01

    Full Text Available This paper presents the experimental investigation results of Ultrasonic Pulse Velocity (UPV tests conducted on roller compacted concrete pavement (RCCP material containing Class F fly ash of as mineral admixture. River sand, M-sand and combination of M-sand and River sand are used as fine aggregate in this experimental work. Three types of fly ash roller compacted concrete mixes are prepared using above three types of fine aggregates and they are designated as Series A (River sand, Series B (manufactured sand and Series C (combination of River sand and M-sand. In each series the fly ash content in place of cement is varied from 0% to 60%. In each series and for different ages of curing (i.e 3, 7, 28 and 90 days forty two cube specimens are cast and tested for compressive strength and UPV. The UPV results of fly ash containing roller compacted concrete pavement (FRCCP show lower values at all ages from 3 days to 90 days in comparison with control mix concrete (0% fly ash in all mixes. However, it is also observed that Series B and C mixes containing fly ash show better results in UPV values, compressive strength and Dynamic Elastic Modulus in comparison to Series A mixes with fly ash. Relationships between compressive strength of FRCCP and UPV and Dynamic Elastic Modulus are proposed for all series mixes. A new empirical equation is proposed to determine the Dynamic Elastic Modulus of FRCCP. Keywords: Compressive strength, Dynamic Elastic Modulus, Fly ash, Roller compacted concrete pavement, Ultrasonic Pulse Velocity

  8. A comparative study of physical and chemical properties of different pozzolanic materials used for roller compacted concrete RCC dams

    OpenAIRE

    Husein Malkawi Abdallah I.; Shatnawi Ehab; Husein Malkawi Dima A.

    2017-01-01

    This paper addresses the feasibility and the efficiency of using Natural Pozzolan and/or Rock flour in Roller Compacted Concrete (RCC) gravity dams. For this purpose, five identical mortar trial mixes were prepared using five different supplementary materials, i.e., fly ash produced in South Africa (proven to be effective in RCC construction), fly ash produced in Turkey, Jordanian natural pozzolan, Saudi natural pozzolan, and rock flour from Mujib Dam basalt quarry. The physical and chemical ...

  9. Seismic response of flexible cylindrical tanks

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, T A; Boley, B A [comps.

    1977-01-01

    An experimental study of the seismic behavior of thin shell circular cylindrical liquid storage tanks is described. The investigation was planned to evaluate the adequacy of present methods of tank design, and was conducted using the Earthquake Simulator Facility of the University of California, Berkeley. The model tank considered in this paper was 6 ft high by 12 ft in diameter, and was welded from thin sheet aluminum to simulate a steel tank 36 feet in diameter. During testing the tank had an open top, held 60 inches of water, and was subjected to a time scaled El Centro (1940) earthquake, amplified to a peak acceleration of 0.5 g. Both base free and base fixed conditions were studied. Results of the experiments demonstrate that fluid pressures included both impulsive and convective components, and that the wave sloshing followed basic theory quite closely. But it also was apparent that the tank flexibility influenced the hydrodynamic pressures, as indicated by pressure amplification in the clamped tank, and by a total change of pressure history in the unclamped case. Significant out of round distortions of the tank were developed, of a three lobe form or the free base case and with four lobes in the fixed base case. Uplift of the tank base was closely related to the out-of-round deformation of the unanchored tank, whereas initial eccentricities apparently caused the section distortions in the anchored system. Stresses in the tank wall do not follow the expected pattern of response to overturning moment; instead they seem to be mainly associated with the section distortions. At present there is no analytical procedure for predicting these distortions .

  10. 77 FR 70423 - Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC...

    Science.gov (United States)

    2012-11-26

    ... Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC; Notice of..., 2012, Black Bear Hydro Partners, LLC, sole licensee (transferor) and Black Bear Development Holdings, LLC and Black Bear SO, LLC (transferees) filed an application for the partial the transfer of licenses...

  11. An Analysis of US Emergency Department Visits From Falls From Skiing, Snowboarding, Skateboarding, Roller-Skating, and Using Nonmotorized Scooters.

    Science.gov (United States)

    Nathanson, Brian H; Ribeiro, Kara; Henneman, Philip L

    2016-07-01

    We analyzed the US incidence of emergency department (ED) visits and hospitalizations for falls from skiing, snowboarding, skateboarding, roller-skating, and nonmotorized scooters in 2011. The outcome was hospital admission from the ED. The primary analysis compared pediatric patients aged 1 to 17 years to adults aged 18 to 44 years. The analysis used ICD-9 E-codes E885.0 to E885.4 using discharge data from the Nationwide Emergency Department Sample, Healthcare Cost and Utilization Project, Agency for Healthcare Research and Quality. Approximately 214 000 ED visits met study criteria. Skiing injuries had the highest percentage of hospitalizations (3.30% in pediatric patients and 6.65% in adults 18-44 years old). Skateboard and snowboard injuries were more likely to require hospitalization than roller skating injuries in pediatric patients (odds ratio = 2.42; 95% CI = 2.14-2.75 and odds ratio = 1.83; 95% CI =1.55-2.15, respectively). In contrast, skateboard and snowboard injuries were less severe than roller-skating injuries in adults. © The Author(s) 2015.

  12. An optimum design on rollers containing the groove with changeable inner diameter based on response surface methodology

    Directory of Open Access Journals (Sweden)

    Xi Zhao

    2016-05-01

    Full Text Available In order to realize the precision plastic forming of the revolving body component with changeable wall thickness, a kind of roller containing grooves with changeable inner diameter is put forward, as the forming mould of the technology of rolling-extrusion. Specifically, first, the arc length of the groove in the roller is designed according to the prediction on the forward slip value during the process of forming, to make accurate control of the actual length of the forming segments; then, to obtain better parameters of the roller structure, a second-order response surface model combining finite element numerical simulation and response surface methodology was put forward, taking the factor of forming uniformity as evaluation index. The result of the experiment shows that, for the formed component, not only the size can meet the needs but also each mechanical property index can be greatly improved, which verify the rationality of the forward slip model and the structural parameter of the optimum model based on the response surface methodology.

  13. Numerical determination of transmission probabilities in cylindrical geometry

    International Nuclear Information System (INIS)

    Queiroz Bogado Leite, S. de.

    1989-11-01

    Efficient methods for numerical calculation of transmission probabilities in cylindrical geometry are presented. Relative errors of the order of 10 -5 or smaller are obtained using analytical solutions and low order quadrature integration schemes. (author) [pt

  14. Cylindrical Field Effect Transistor: A Full Volume Inversion Device

    KAUST Repository

    Fahad, Hossain M.

    2010-01-01

    inversion in the body. However, these devices are still limited by lithographic and processing challenges making them unsuitable for commercial production. This thesis explores a unique device structure called the CFET (Cylindrical Field Effect Transistors

  15. Response of an electrostatic probe for a right cylindrical spacer

    DEFF Research Database (Denmark)

    Rerup, T; Crichton, George C; McAllister, Iain Wilson

    1994-01-01

    During the last decade many experimental studies of surface charge phenomena have been undertaken employing right cylindrical spacers. Measurement of the surface charge was performed using small electrostatic field probes to scan across the dielectric surface. Charges are electrostatically induced...

  16. Analysis of Hall Probe Precise Positioning with Cylindrical Permanent Magnet

    International Nuclear Information System (INIS)

    Belicev, P.; Vorozhtsov, A.S.; Vorozhtsov, S.B.

    2007-01-01

    Precise positioning of a Hall probe for cyclotron magnetic field mapping, using cylindrical permanent magnets, was analyzed. The necessary permanent magnet parameters in order to achieve ±20 μm position precision, were determined. (author)

  17. Improving the performance parameters of metal cylindrical grid shell ...

    African Journals Online (AJOL)

    Improving the performance parameters of metal cylindrical grid shell structures. ... Finite element models are designed taking into account minimization of production and ... The force factors and deformation parameters of the basic circuits of a ...

  18. Rotating solitary wave at the wall of a cylindrical container

    KAUST Repository

    Amaouche, Mustapha; Ait Abderrahmane, Hamid; Vatistas, Georgios H.

    2013-01-01

    This paper deals with the theoretical modeling of a rotating solitary surface wave that was observed during water drainage from a cylindrical reservoir, when shallow water conditions were reached. It represents an improvement of our previous study

  19. A single-electron current in a cylindrical nanolayer

    International Nuclear Information System (INIS)

    Kazaryan, E.M.; Aghekyan, N.G.; Sarkisyan, H.A.

    2012-01-01

    The orbital current and the spin magnetic moment current of an electron in a cylindrical nanolayer are investigated. It is shown that under certain conditions, the main contribution to the total current is specified by the spin magnetic moment current

  20. Introgressive hybridization: brown bears as vectors for polar bear alleles.

    Science.gov (United States)

    Hailer, Frank

    2015-03-01

    The dynamics and consequences of introgression can inform about numerous evolutionary processes. Biologists have therefore long been interested in hybridization. One challenge, however, lies in the identification of nonadmixed genotypes that can serve as a baseline for accurate quantification of admixture. In this issue of Molecular Ecology, Cahill et al. (2015) analyse a genomic data set of 28 polar bears, eight brown bears and one American black bear. Polar bear alleles are found to be introgressed into brown bears not only near a previously identified admixture zone on the Alaskan Admiralty, Baranof and Chichagof (ABC) Islands, but also far into the North American mainland. Elegantly contrasting admixture levels at autosomal and X chromosomal markers, Cahill and colleagues infer that male-biased dispersal has spread these introgressed alleles away from the Late Pleistocene contact zone. Compared to a previous study on the ABC Island population in which an Alaskan brown bear served as a putatively admixture-free reference, Cahill et al. (2015) utilize a newly sequenced Swedish brown bear as admixture baseline. This approach reveals that brown bears have been impacted by introgression from polar bears to a larger extent (up to 8.8% of their genome), than previously known, including the bear that had previously served as admixture baseline. No evidence for introgression of brown bear into polar bear is found, which the authors argue could be a consequence of selection. Besides adding new exciting pieces to the puzzle of polar/brown bear evolutionary history, the study by Cahill and colleagues highlights that wildlife genomics is moving from analysing single genomes towards a landscape genomics approach. © 2015 John Wiley & Sons Ltd.

  1. Instrumented roll technology for the design space development of roller compaction process.

    Science.gov (United States)

    Nesarikar, Vishwas V; Vatsaraj, Nipa; Patel, Chandrakant; Early, William; Pandey, Preetanshu; Sprockel, Omar; Gao, Zhihui; Jerzewski, Robert; Miller, Ronald; Levin, Michael

    2012-04-15

    Instrumented roll technology on Alexanderwerk WP120 roller compactor was developed and utilized successfully for the measurement of normal stress on ribbon during the process. The effects of process parameters such as roll speed (4-12 rpm), feed screw speed (19-53 rpm), and hydraulic roll pressure (40-70 bar) on normal stress and ribbon density were studied using placebo and active pre-blends. The placebo blend consisted of 1:1 ratio of microcrystalline cellulose PH102 and anhydrous lactose with sodium croscarmellose, colloidal silicon dioxide, and magnesium stearate. The active pre-blends were prepared using various combinations of one active ingredient (3-17%, w/w) and lubricant (0.1-0.9%, w/w) levels with remaining excipients same as placebo. Three force transducers (load cells) were installed linearly along the width of the roll, equidistant from each other with one transducer located in the center. Normal stress values recorded by side sensors and were lower than normal stress values recorded by middle sensor and showed greater variability than middle sensor. Normal stress was found to be directly proportional to hydraulic pressure and inversely to screw to roll speed ratio. For active pre-blends, normal stress was also a function of compressibility. For placebo pre-blends, ribbon density increased as normal stress increased. For active pre-blends, in addition to normal stress, ribbon density was also a function of gap. Models developed using placebo were found to predict ribbon densities of active blends with good accuracy and the prediction error decreased as the drug concentration of active blend decreased. Effective angle of internal friction and compressibility properties of active pre blend may be used as key indicators for predicting ribbon densities of active blend using placebo ribbon density model. Feasibility of on-line prediction of ribbon density during roller compaction was demonstrated using porosity-pressure data of pre-blend and normal stress

  2. Wayside Bearing Fault Diagnosis Based on a Data-Driven Doppler Effect Eliminator and Transient Model Analysis

    Science.gov (United States)

    Liu, Fang; Shen, Changqing; He, Qingbo; Zhang, Ao; Liu, Yongbin; Kong, Fanrang

    2014-01-01

    A fault diagnosis strategy based on the wayside acoustic monitoring technique is investigated for locomotive bearing fault diagnosis. Inspired by the transient modeling analysis method based on correlation filtering analysis, a so-called Parametric-Mother-Doppler-Wavelet (PMDW) is constructed with six parameters, including a center characteristic frequency and five kinematic model parameters. A Doppler effect eliminator containing a PMDW generator, a correlation filtering analysis module, and a signal resampler is invented to eliminate the Doppler effect embedded in the acoustic signal of the recorded bearing. Through the Doppler effect eliminator, the five kinematic model parameters can be identified based on the signal itself. Then, the signal resampler is applied to eliminate the Doppler effect using the identified parameters. With the ability to detect early bearing faults, the transient model analysis method is employed to detect localized bearing faults after the embedded Doppler effect is eliminated. The effectiveness of the proposed fault diagnosis strategy is verified via simulation studies and applications to diagnose locomotive roller bearing defects. PMID:24803197

  3. On cylindrically converging shock waves shaped by obstacles

    Energy Technology Data Exchange (ETDEWEB)

    Eliasson, V; Henshaw, W D; Appelo, D

    2007-07-16

    Motivated by recent experiments, numerical simulations were performed of cylindrically converging shock waves. The converging shocks impinged upon a set of zero to sixteen regularly space obstacles. For more than two obstacles the resulting diffracted shock fronts formed polygonal shaped patterns near the point of focus. The maximum pressure and temperature as a function of number of obstacles were studied. The self-similar behavior of cylindrical, triangular and square-shaped shocks were also investigated.

  4. Theory and modeling of cylindrical thermo-acoustic transduction

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Lihong, E-mail: lhtong@ecjtu.edu.cn [School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang, Jiangxi (China); Lim, C.W. [Department of Architecture and Civil Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR (China); Zhao, Xiushao; Geng, Daxing [School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang, Jiangxi (China)

    2016-06-03

    Models both for solid and thinfilm-solid cylindrical thermo-acoustic transductions are proposed and the corresponding acoustic pressure solutions are obtained. The acoustic pressure for an individual carbon nanotube (CNT) as a function of input power is investigated analytically and it is verified by comparing with the published experimental data. Further numerical analysis on the acoustic pressure response and characteristics for varying input frequency and distance are also examined both for solid and thinfilm-solid cylindrical thermo-acoustic transductions. Through detailed theoretical and numerical studies on the acoustic pressure solution for thinfilm-solid cylindrical transduction, it is concluded that a solid with smaller thermal conductivity favors to improve the acoustic performance. In general, the proposed models are applicable to a variety of cylindrical thermo-acoustic devices performing in different gaseous media. - Highlights: • Theory and modeling both for solid and thinfilm-solid cylindrical thermo-acoustic transductions are proposed. • The modeling is verified by comparing with the published experimental data. • Acoustic response characteristics of cylindrical thermo-acoustic transductions are predicted by the proposed model.

  5. Micropatterning on cylindrical surfaces via electrochemical etching using laser masking

    International Nuclear Information System (INIS)

    Cho, Chull Hee; Shin, Hong Shik; Chu, Chong Nam

    2014-01-01

    Highlights: • Various micropatterns were fabricated on the cylindrical surface of a stainless steel shaft. • Selective electrochemical dissolution was achieved via a series process of laser masking and electrochemical etching. • Laser masking characteristics on the non-planar surface were investigated. • A uniform mask layer was formed on the cylindrical surface via synchronized laser line scanning with a rotary system. • The characteristics of electrochemical etching on the non-planar surface were investigated. - Abstract: This paper proposes a method of selective electrochemical dissolution on the cylindrical surfaces of stainless steel shafts. Selective electrochemical dissolution was achieved via electrochemical etching using laser masking. A micropatterned recast layer was formed on the surface via ytterbium-doped pulsed fiber laser irradiation. The micropatterned recast layer could be used as a mask layer during the electrochemical etching process. Laser masking condition to form adequate mask layer on the planar surface for etching cannot be used directly on the non-planar surface. Laser masking condition changes depending on the morphological surface. The laser masking characteristics were investigated in order to form a uniform mask layer on the cylindrical surface. To minimize factors causing non-uniformity in the mask layer on the cylindrical surface, synchronized laser line scanning with a rotary system was applied during the laser masking process. Electrochemical etching characteristics were also investigated to achieve deeper etched depth, without collapsing the recast layer. Consequently, through a series process of laser masking and electrochemical etching, various micropatternings were successfully performed on the cylindrical surfaces

  6. Self lubricating fluid bearings

    International Nuclear Information System (INIS)

    Kapich, D.D.

    1980-01-01

    The invention concerns self lubricating fluid bearings, which are used in a shaft sealed system extending two regions. These regions contain fluids, which have to be isolated. A first seal is fluid tight for the first region between the carter shaft and the shaft. The second seal is fluid tight between the carter and the shaft, it communicates with the second region. The first fluid region is the environment surrounding the shaft carter. The second fluid region is a part of a nuclear reactor which contains the cooling fluid. The shaft is conceived to drive a reactor circulating and cooling fluid [fr

  7. Three-dimensional earthquake analysis of roller-compacted concrete dams

    Directory of Open Access Journals (Sweden)

    M. E. Kartal

    2012-07-01

    Full Text Available Ground motion effect on a roller-compacted concrete (RCC dams in the earthquake zone should be taken into account for the most critical conditions. This study presents three-dimensional earthquake response of a RCC dam considering geometrical non-linearity. Besides, material and connection non-linearity are also taken into consideration in the time-history analyses. Bilinear and multilinear kinematic hardening material models are utilized in the materially non-linear analyses for concrete and foundation rock respectively. The contraction joints inside the dam blocks and dam–foundation–reservoir interaction are modeled by the contact elements. The hydrostatic and hydrodynamic pressures of the reservoir water are modeled with the fluid finite elements based on the Lagrangian approach. The gravity and hydrostatic pressure effects are employed as initial condition before the strong ground motion. In the earthquake analyses, viscous dampers are defined in the finite element model to represent infinite boundary conditions. According to numerical solutions, horizontal displacements increase under hydrodynamic pressure. Besides, those also increase in the materially non-linear analyses of the dam. In addition, while the principle stress components by the hydrodynamic pressure effect the reservoir water, those decrease in the materially non-linear time-history analyses.

  8. EAF Slag Aggregate in Roller-Compacted Concrete Pavement: Effects of Delay in Compaction

    Directory of Open Access Journals (Sweden)

    My Ngoc-Tra Lam

    2018-04-01

    Full Text Available This study investigates the effect of delay in compaction on the optimum moisture content and the mechanical propertie s (i.e., compressive strength, ultrasonic pulse velocity, splitting tensile strength, and modulus of elasticity of roller-compacted concrete pavement (RCCP made of electric arc furnace (EAF slag aggregate. EAF slag with size in the range of 4.75–19 mm was used to replace natural coarse aggregate in RCCP mixtures. A new mixing method was proposed for RCCP using EAF slag aggregate. The optimum moisture content of RCCP mixtures in this study was determined by a soil compaction method. The Proctor test assessed the optimum moisture content of mixtures at various time after mixing completion (i.e., 0, 15, 30, 60, and 90 min. Then, the effect of delay in compaction on the mechanical properties of RCCP mixtures at 28 days of age containing EAF slag aggregate was studied. The results presented that the negative effect on water content in the mixture caused by the higher water absorption characteristic of EAF slag was mitigated by the new mixing method. The optimum water content and maximum dry density of RCCP experience almost no effect from the delay in compaction. The compressive strength and splitting tensile strength of RCCP using EAF slag aggregate fulfilled the strength requirements for pavement with 90 min of delay in compaction.

  9. Extracorporeal tubing in the roller pump raceway: physical changes and particulate generation.

    Science.gov (United States)

    Spiwak, Allison J Bednarski; Horbal, Alexander; Leatherbury, Robert; Hansford, Derek J

    2008-09-01

    Plasticized polyvinyl chloride tubing is used as the blood conduit in the heart lung bypass circuit. The section in the roller pump undergoes rigorous compression. Fatigue leads to material changes in weight and length of the bulk material. Particles are released during normal pump operation. This study evaluates the time course of particle loss. Three segments of 1/2" ID tubing run in the raceway for 30-minute, 1-hour, or 2-hour. The fluid path of each segment includes an oxygenator; a castor oil blend was used for the prime. The 5 mL sample was acquired at 10 minute intervals. Raceway tubing segments were measured for a change in weight and length. The same procedure repeated with 1/4" ID and 3/8" ID tubing. All tubing increased at least 5 mm by the 2-hour trial. There were no remarkable changes in weight. Particles were measured for size and percent volume. Tubing with 1/2" ID performed most consistently for particle release during all trials. Particles were observed as small as 1 nm. Particles as large as 3 micron could be confirmed. For all tubing there was particle release by 30 minutes. Perfusionists must consider tubing inner diameter and wall thickness in choosing the pPVC for the raceway in order to minimize particulate emboli. This research suggests that 3/8" ID tubing produces spalls inconsistently compared to 2" ID tubing. Thinner wall thickness tubing also has the potential to limit spall formation.

  10. Structural Design and Economic Evaluation of Roller Compacted Concrete Pavement with Recycled Aggregates

    Science.gov (United States)

    Abut, Yavuz; Taner Yildirim, Salih

    2017-10-01

    Using recycled aggregates in the concrete offers advantages in many areas such as waste management, energy save and natural resources, conservation of ecological balance, low CO2 emissions, and users are encouraged in this regard to use these materials. In this study, the profit / loss account arising in the structural design phase was investigated when Reclaimed Asphalt Pavement (RAP), which is limited to use in Roller Compacted Concrete (RCC) pavements, was used as coarse aggregate. RAP materials were used as coarse aggregates by the levels of 0%, 15% and 20% and mechanical properties such as compressive strength, flexural strength, splitting tensile strength and modulus of elasticity were investigated. In the last stage, the mechanical properties obtained from these experimental studies were entered into KENSLABS software as input, and the slab layer thicknesses were determined according to three different subgrade conditions and a certain fatigue criterion. According to the results, it has been determined that the use of RAP at a level of 20% is a serious reducing effect on mechanical properties and and the use of RAP at a level of 15% does not bring a great economic benefit but it is reasonable to use it as coarse aggregate in RCC mixes in consideration of environmental effects.

  11. Nanoprecipitation in bearing steels

    International Nuclear Information System (INIS)

    Barrow, A.T.W.; Rivera-Diaz-del-Castillo, P.E.J.

    2011-01-01

    θ-phase is the main hardening species in bearing steels and appears in both martensitically and bainitically hardened microstructures. This work presents a survey of the microstrucural features accompanying nanoprecipitation in bearing steels. Nanoprecipitate structures formed in 1C-1.5Cr wt.% with additions of Cr, Mn, Mo, Si and Ni are studied. The work is combined with thermodynamic calculations and neural networks to predict the expected matrix composition, and whether this will transform martensitically or bainitically. Martensite tetragonality, composition and the amount of retained austenite are related to hardness and the type of nanoprecipitate structures in martensitic grades. The θ-phase volume fraction, the duration of the bainite to austenite transformation and the amount of retained austenite are related to hardness and a detailed quantitative description of the precipitate nanostructures. Such description includes compositional studies using energy-dispersive spectroscopy, which shows that nanoprecipitate formation takes place under paraequilibrium. Special attention is devoted to a novel two-step bainite tempering process which shows maximum hardness; we prove that this is the most effective process for incorporating solute into the precipitates, which are finer than those resulting from one-step banitic transformation processes.

  12. Superconducting bearings in flywheels

    Energy Technology Data Exchange (ETDEWEB)

    Coombs, T.A.; Campbell, A.M.; Ganney, I.; Lo, W. [Cambridge Univ. (United Kingdom). Interdisciplinary Research Centre in Superconductivity (IRC); Twardowski, T. [International Energy Systems, Chester High Road, Neston, South Wirral (United Kingdom); Dawson, B. [British Nuclear Fuels, Capenhurst, South Wirral (United Kingdom)

    1998-05-01

    Investigations are being carried out into the use of superconducting magnetic bearings to levitate energy storage flywheels. In a planned program of work, Cambridge University are aiming to produce a practical bearing system for Pirouette(TM). The Pirouette(TM) system is designed to provide 5 kWh of recoverable energy which is currently recoverable at a rate of 5 kW (future revisions will provide up to 50 kW). IES (a British Nuclear Fuels subsidiary) the owners of the Pirouette(TM) machine have supplied Cambridge with a flywheel. This flywheel weighs >40 kg and is being levitated using an Evershed-type arrangement in which the superconductor is being used to stabilize the interaction between two magnets. To date we have demonstrated stable levitation in static and low speed tests in a rig designed for low speeds of rotation in air. A second rig which is currently under construction at BNFL will run in vacuum at speeds of up to 50 (orig.) 5 refs.

  13. Optimum IMFs Selection Based Envelope Analysis of Bearing Fault Diagnosis in Plunger Pump

    Directory of Open Access Journals (Sweden)

    Wenliao Du

    2016-01-01

    Full Text Available As the plunger pump always works in a complicated environment and the hydraulic cycle has an intrinsic fluid-structure interaction character, the fault information is submerged in the noise and the disturbance impact signals. For the fault diagnosis of the bearings in plunger pump, an optimum intrinsic mode functions (IMFs selection based envelope analysis was proposed. Firstly, the Wigner-Ville distribution was calculated for the acquired vibration signals, and the resonance frequency brought on by fault was obtained. Secondly, the empirical mode decomposition (EMD was employed for the vibration signal, and the optimum IMFs and the filter bandwidth were selected according to the Wigner-Ville distribution. Finally, the envelope analysis was utilized for the selected IMFs filtered by the band pass filter, and the fault type was recognized by compared with the bearing character frequencies. For the two modes, inner race fault and compound fault in the inner race and roller of rolling element bearing in plunger pump, the experiments show that a promising result is achieved.

  14. Roller Testing to Mimic Damage of the ISS SARJ Ring and Durability Test to Simulate Fifteen Years of SARJ Operation Using the Damaged Surface

    Science.gov (United States)

    Krantz, Timothy L.; Elchert, Justin P.; DellaCorte, Christopher; Dube, Michael J.

    2016-01-01

    The International Space Station's starboard Solar Alpha Rotary Joint (SARJ) experienced a breakdown of the joint's race ring surface. The starboard SARJ mechanism was cleaned and lubricated with grease. To provide some guidance on the expected behavior of the damaged SARJ ring with continued operations, experiments were conducted using rollers and a vacuum roller test rig. The approach of the experimental work involved three main steps: (1) initiate damage using conditions representative of the SARJ with inadequate lubrication; (2) propagate the damage by operating the test rollers without lubrication; and (3) assess the durability of the roller by testing to simulate the equivalent of 15 years of SARJ operation on the damaged surface assuming adequate grease lubrication. During the rig testing, additional and/or replacement grease was introduced at regular intervals to maintain good lubrication in the rig. The damage to the nitride layer continued even after application of grease. The grease lubrication proved to be effective for limiting the value of the axial force that can be developed. Limiting the axial force on the SARJ mechanism is important since the larger the axial force the more concentrated the load pressure becomes on the blend-radius location on the SARJ roller. After the testing simulating 15 years of SARJ operations, the wear depths were the order of 0.2 mm for the nitrided 15-5 roller and the order of 0.06 mm for the mating 440C roller. Metallographic inspections were done to search for indications of impending fatigue or other fracture indications that might eventually propagate and cause structural failure. There were no indications or features found that could eventually compromise structural integrity.

  15. Computational design of rolling bearings

    CERN Document Server

    Nguyen-Schäfer, Hung

    2016-01-01

    This book comprehensively presents the computational design of rolling bearings dealing with many interdisciplinary difficult working fields. They encompass elastohydrodynamics (EHD), Hertzian contact theory, oil-film thickness in elastohydrodynamic lubrication (EHL), bearing dynamics, tribology of surface textures, fatigue failure mechanisms, fatigue lifetimes of rolling bearings and lubricating greases, Weibull distribution, rotor balancing, and airborne noises (NVH) in the rolling bearings. Furthermore, the readers are provided with hands-on essential formulas based on the up-to-date DIN ISO norms and helpful examples for computational design of rolling bearings. The topics are intended for undergraduate and graduate students in mechanical and material engineering, research scientists, and practicing engineers who want to understand the interactions between these working fields and to know how to design the rolling bearings for automotive industry and many other industries.

  16. Hydrostatic and hybrid bearing design

    CERN Document Server

    Rowe, W B

    1983-01-01

    Hydrostatic and Hybrid Bearing Design is a 15-chapter book that focuses on the bearing design and testing. This book first describes the application of hydrostatic bearings, as well as the device pressure, flow, force, power, and temperature. Subsequent chapters discuss the load and flow rate of thrust pads; circuit design, flow control, load, and stiffness; and the basis of the design procedures and selection of tolerances. The specific types of bearings, their design, dynamics, and experimental methods and testing are also shown. This book will be very valuable to students of engineering des

  17. PECULIARITIES OF ASSIGNMENT OF ROLLING BEARING MOUNTING AND PARAMETERS OF GEOMETRIC ACCURACY OF MOUNTING SURFACES OF SHAFTS AND FRAMES

    Directory of Open Access Journals (Sweden)

    Adamenko Yu. І.

    2017-04-01

    Full Text Available The standards and methods concerning assignment of rolling bearing fit with shafts and frames via example of bearing 6-208 are analyzed. We set certain differences of recommendations according to GOST 3325-85, "Rolling bearings. Tolerance zones and technical requirements to mounting surfaces of shafts and frames. Attachment" and by reference of rolling bearing manufacturers. The following factors should be taken into consideration when assigning the mounting with the tension the internal ring of the bearing with shaft and mounting with a gap in the outer ring with a housing bore. The methods of achieving accuracy of mounting surfaces of shafts and frames via form tolerance assignment: roundness tolerance, profile of longitudinal cut, cross section, cylindricity and others. It is possible to limit the bearing rings in different ways, for example appointing the cylindrical mounting surfaces and bead end surfaces the appropriate tolerances, namely: coaxiality tolerance or full radial beat of mounting surfaces, and also perpendicularity tolerance, butt beats and full butt beats of mounting end surfaces. We suggest to expand methods of achieving the accuracy of shafts and frames depending on seriation of production and production operations metrology support.

  18. Power deposition in a cylindrical geometry using B-10 coatings

    International Nuclear Information System (INIS)

    Chung, A.K.; Prelas, M.A.

    1983-01-01

    The transport of charged particles produced by 10 B (n, α) Li and 235 U (n, νn) ff nuclear reactions in a two region cylindrical geometry is predicted. We employed a mean-range straight-flight approximation to calculate the power deposition by the charged particles in a gaseous medium. Our model demonstrated some features in a cylindrical experiment which were suspected but not proven. In the common slab model used by Guyot et al 1 and Romero 2 , the spatial distribution of power deposition is much flatter than it would be in a cylindrical model. A steeper gradient in the power deposition is expected in a cylindrical geometry than in a slab geometry. We also found that for a standard thickness of Boron-10 coating (1.73 μm) used in NPLs, the expected efficiency of a cylindrical geometry (7.5%) is much lower than the 12% efficiency predicted by the slab model. Indeed the use of slab geometry in modeling current NPL experimental devices is not accurate

  19. Sensitivity optimization in whispering gallery mode optical cylindrical biosensors

    Science.gov (United States)

    Khozeymeh, F.; Razaghi, M.

    2018-01-01

    Whispering-gallery-mode resonances propagated in cylindrical resonators have two angular and radial orders of l and i. In this work, the higher radial order whispering-gallery-mode resonances, (i = 1 - 4), at a fixed l are examined. The sensitivity of theses resonances is analysed as a function of the structural parameters of the cylindrical resonator like different radii and refractive index of composed material of the resonator. A practical application where cylindrical resonators are used for the measurement of glucose concentration in water is presented as a biosensor demonstrator. We calculate the wavelength shifts of the WG1-4, in several glucose/water solutions, with concentrations spanning from 0.0% to 9.0.% (weight/weight). Improved sensitivity can be achieved using multi-WGM cylindrical resonators with radius of R = 100 μm and resonator composed material of MgF 2 with refractive index of nc = 1.38. Also the effect of polarization on sensitivity is considered for all four WGMs. The best sensitivity of 83.07 nm/RIU for the fourth WGM with transverse magnetic polarization, is reported. These results propose optimized parameters aimed to fast designing of cylindrical resonators as optical biosensors, where both the sensitivity and the geometries can be optimized.

  20. The decrease of cylindrical pempek quality during boiling

    Science.gov (United States)

    Karneta, R.; Gultom, N. F.

    2017-09-01

    The research objective was to study the effects of temperature and formulation on quality of pempek lenjer during boiling. Treatments in this study were four levels of pempek formulation and five levels of temperature. Data was processed by using analysis of variance (Anova). If test results showed that samples were significantly different or highly significantly different, then further test was conducted by using Honestly Significant Different. The results showed that chemical analysis showed that fish dominant formula of cylindrical pempek had higher water content, protein content, lipid content and ash content than that of tapioca starch dominant formula, but it had lower carbohydrate content and fibre content than that of tapioca starch dominant formula.The higher the temperature at center point of cylindrical pempek, the lower the chemical quality of cylindrical pempek. The effect of formula on physical quality of cylindrical pempek showed that tapioca starch dominant formula had more rubbery texture, more neutral pH and brighter color than that of fish dominant formula.The temperature change had no significant effect on texture and pH of cylindrical pempek, but it had significant effect on lightness, intensity and chromatic color especially after exceeding optimum time of boiling.

  1. Novel spherical hohlraum with cylindrical laser entrance holes and shields

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Ke [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Zheng, Wudi [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)

    2014-09-15

    Our recent works [K. Lan et al., Phys. Plasmas 21, 010704 (2014); K. Lan et al., Phys. Plasmas 21, 052704 (2014)] have shown that the octahedral spherical hohlraums are superior to the cylindrical hohlraums in both higher symmetry during the capsule implosion and lower backscatter without supplementary technology. However, both the coupling efficiency from the drive laser energy to the capsule and the capsule symmetry decrease remarkably when larger laser entrance holes (LEHs) are used. In addition, the laser beams injected at angles > 45° transport close to the hohlraum wall, thus the wall blowoff causes the LEH to close faster and results in strong laser plasma interactions inside the spherical hohlraums. In this letter, we propose a novel octahedral hohlraum with LEH shields and cylindrical LEHs to alleviate these problems. From our theoretical study, with the LEH shields, the laser coupling efficiency is significantly increased and the capsule symmetry is remarkably improved in the spherical hohlraums. The cylindrical LEHs take advantage of the cylindrical hohlraum near the LEH and mitigate the influence of the blowoff on laser transport inside a spherical hohlraum. The cylindrical LEHs can also be applied to the rugby and elliptical hohlraums.

  2. Novel spherical hohlraum with cylindrical laser entrance holes and shields

    International Nuclear Information System (INIS)

    Lan, Ke; Zheng, Wudi

    2014-01-01

    Our recent works [K. Lan et al., Phys. Plasmas 21, 010704 (2014); K. Lan et al., Phys. Plasmas 21, 052704 (2014)] have shown that the octahedral spherical hohlraums are superior to the cylindrical hohlraums in both higher symmetry during the capsule implosion and lower backscatter without supplementary technology. However, both the coupling efficiency from the drive laser energy to the capsule and the capsule symmetry decrease remarkably when larger laser entrance holes (LEHs) are used. In addition, the laser beams injected at angles > 45° transport close to the hohlraum wall, thus the wall blowoff causes the LEH to close faster and results in strong laser plasma interactions inside the spherical hohlraums. In this letter, we propose a novel octahedral hohlraum with LEH shields and cylindrical LEHs to alleviate these problems. From our theoretical study, with the LEH shields, the laser coupling efficiency is significantly increased and the capsule symmetry is remarkably improved in the spherical hohlraums. The cylindrical LEHs take advantage of the cylindrical hohlraum near the LEH and mitigate the influence of the blowoff on laser transport inside a spherical hohlraum. The cylindrical LEHs can also be applied to the rugby and elliptical hohlraums

  3. A cylindrical specimen holder for electron cryo-tomography

    International Nuclear Information System (INIS)

    Palmer, Colin M.; Löwe, Jan

    2014-01-01

    The use of slab-like flat specimens for electron cryo-tomography restricts the range of viewing angles that can be used. This leads to the “missing wedge” problem, which causes artefacts and anisotropic resolution in reconstructed tomograms. Cylindrical specimens provide a way to eliminate the problem, since they allow imaging from a full range of viewing angles around the tilt axis. Such specimens have been used before for tomography of radiation-insensitive samples at room temperature, but never for frozen-hydrated specimens. Here, we demonstrate the use of thin-walled carbon tubes as specimen holders, allowing the preparation of cylindrical frozen-hydrated samples of ribosomes, liposomes and whole bacterial cells. Images acquired from these cylinders have equal quality at all viewing angles, and the accessible tilt range is restricted only by the physical limits of the microscope. Tomographic reconstructions of these specimens demonstrate that the effects of the missing wedge are substantially reduced, and could be completely eliminated if a full tilt range was used. The overall quality of these tomograms is still lower than that obtained by existing methods, but improvements are likely in future. - Highlights: • The missing wedge is a serious problem for electron cryo-tomography. • Cylindrical specimens allow the missing wedge to be eliminated. • Carbon nanopipettes can be used as cylindrical holders for tomography of frozen-hydrated specimens. • Cryo-tomography of cylindrical biological samples demonstrates a reduction of deleterious effects associated with the missing wedge

  4. The effect of extrusion and drying on roller techniques concerning the rheological characteristics of rice-, corn-, sweet potato-, bean- and cassava root- and leaf- based composite flour

    Directory of Open Access Journals (Sweden)

    Johanna Aristizábal Galvis

    2013-01-01

    Full Text Available Promoting food security in Latin-America and the Caribbean is directly related to agricultural products. The region faces a food crisis which has reduced large population groups’ access to food. This work contributes to the study of obtaining precooked composite flour made from biofortified crops using protein, vitamin A and/or minerals. This study evaluated the effect of precooked flour’s composition and precooking on its solubility in water, water absorption capacity, consistency and viscosity; such flour was obtained by extrusion and drying on rollers. The composite flours were obtained from cassava roots, sweet potato tubers, corn, rice and bean grains and cassava leaves. Four composite flours were formulated taking four- to six-year-old children’s daily nutrient requirements (protein, iron, zinc and beta-carotenes as a basis. The extruder was operated at 90ºC, 300 rpm screw rotation speed, 17.64 g/min feed flow, with 30% moisture mixture. The dryer rollers were operated at 4 rpm roller rotation speed, 90ºC surface temperature and 1 mm separation between rollers. It was determined that flour dried on rollers led to more complete cooking and modified starch granule structure than precooking by extrusion, thereby producing flour having greater solubility in water, less water absorption, higher consistency and smaller viscosity, comparable to that of pattern flour.

  5. Importance of using roller compacted concrete in techno-economic investigation and design of small dams

    Science.gov (United States)

    Rouissat, Bouchrit; Smail, N.; Zenagui, S.

    2017-12-01

    In recent years, and under constraints caused by persistent drought, Algeria has launched a new mobilization strategy for surface water resources from small and medium dams. However, by making a review of the studies and achievements of twenty small dams in the west of Algeria, some deficiencies appeared. In addition to reservoir siltation assessment, operation spillways have been the major constraint on the reliability of these types of dams. The objective of this paper is to use the roller compacted concrete (RCC) for small dams' design for the benefit it offers and its ability to incorporate spillways. The development of this reflection was applied to the Khneg Azir earth dam situated in southwest of Algeria. Its uncontrolled lateral spillway has registered significant damage following the flood of October 2005, amounted, at that time, to more than 100 million Algerian dinars (1 million US Dollars). The present research encompasses a technical and economical comparative analysis concerning multiple criteria dam design types coupled with the conjugation of the spillways. Thus, on the basis of financial estimates calculated for all design types, the variant RCC remains competitive with that of the earth dam's spillway isolated (Less than 40% of the cost). To assess the mechanical behavior of the foundations for both types of dams, (earth and RCC dams), numerical modeling has been undertaken, according to the comparative analysis of deformations in the foundations. Analysis of deformations showed that the average foundation deformations was between (0.052-0.85) m for earth dam and (0.023-0.373) m for RCC dam. These economical and technical considerations open up important prospects for the use of RCC in the design of small dams.

  6. Closure Report for Corrective Action Unit 407: Roller Coaster RADSAFE Area, Tonopah Test Range, Nevada

    International Nuclear Information System (INIS)

    Fitzmaurice, T. M.

    2001-01-01

    This closure report (CR) provides documentation for the closure of the Roller Coaster RADSAFE Area (RCRSA) Corrective Action Unit (CAU) 407 identified in the Federal Facility Agreement and Consent Order (FFACO) (Nevada Division of Environmental Protection [NDEP] et al., 1996). CAU 407 is located at the Tonopah Test Range (TTR), Nevada. The TTR is approximately 225 kilometers (km) (140 miles [mi]) northwest of Las Vegas, Nevada (Figure 1). The RCRSA is located on the northeast comer of the intersection of Main Road and Browne's Lake Road, which is approximately 8 km (5 mi) south of Area 3 (Figure 1). The RCRSA was used during May and June of 1963 to decontaminate vehicles, equipment, and personnel from the Double Tracks and Clean Slate tests. Investigation of the RCRSA was conducted from June through November of 1998. A Corrective Action Decision Document (CADD) (U.S. Department of Energy, Nevada Operations Office [DOEN], 1999) was approved in October of 1999. The purpose of this CR is to: Document the closure activities as proposed in the Corrective Action Plan (CAP) (DOEM, 2000). Obtain a Notice of Completion from the NDEP. Recommend the movement of CAU 407 from Appendix III to Appendix IV of the FFACO. The following is the scope of the closure actions implemented for CAU 407: Removal and disposal of surface soils which were over three times background for the area. Soils identified for removal were disposed of at the Area 5 Radioactive Waste Management Site (RWMS) at the Nevada Test Site (NTS). Excavated areas were backfilled with clean borrow soil located near the site. A soil cover was constructed over the waste disposal pit area, where subsurface constituents of concern remain. The site was fenced and posted as an ''Underground Radioactive Material'' area

  7. Corrective Action Plan for Corrective Action Unit 407: Roller Coaster RADSAFE Area, Tonopah Test Range, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    T. M. Fitzmaurice

    2000-05-01

    This Corrective Action Plan (CAP) has been prepared for the Roller Coaster RADSAFE Area Corrective Action Unit 407 in accordance with the Federal Facility and Consent Order (Nevada Division of Environmental Protection [NDEP] et al., 1996). This CAP provides the methodology for implementing the approved Corrective Action Alternative as listed in the Corrective Action Decision Document (U.S. Department of Energy, Nevada Operations Office, 1999). The RCRSA was used during May and June of 1963 to decontaminate vehicles, equipment, and personnel from the Clean Slate tests. The Constituents of Concern (COCs) identified during the site characterization include plutonium, uranium, and americium. No other COCS were identified. The following closure actions will be implemented under this plan: (1) Remove and dispose of surface soils which are over three times background for the area. Soils identified for removal will be disposed of at an approved disposal facility. Excavated areas will be backfilled with clean borrow soil fi-om a nearby location. (2) An engineered cover will be constructed over the waste disposal pit area where subsurface COCS will remain. (3) Upon completion of the closure and approval of the Closure Report by NDEP, administrative controls, use restrictions, and site postings will be used to prevent intrusive activities at the site. Barbed wire fencing will be installed along the perimeter of this unit. Post closure monitoring will consist of site inspections to determine the condition of the engineered cover. Any identified maintenance and repair requirements will be remedied within 90 working days of discovery and documented in writing at the time of repair. Results of all inspections/repairs for a given year will be addressed in a single report submitted annually to the NDEP.

  8. Long-Life, Lightweight, Multi-Roller Traction Drives for Planetary Vehicle Surface Exploration

    Science.gov (United States)

    Klein, Richard C.; Fusaro, Robert L.; Dimofte, Florin

    2012-01-01

    NASA s initiative for Lunar and Martian exploration will require long lived, robust drive systems for manned vehicles that must operate in hostile environments. The operation of these mechanical drives will pose a problem because of the existing extreme operating conditions. Some of these extreme conditions include operating at a very high or very cold temperature, operating over a wide range of temperatures, operating in very dusty environments, operating in a very high radiation environment, and operating in possibly corrosive environments. Current drive systems use gears with various configurations of teeth. These gears must be lubricated with oil (or grease) and must have some sort of a lubricant resupply system. For drive systems, oil poses problems such as evaporation, becoming too viscous and eventually freezing at cold temperatures, being too thin to lubricate at high temperatures, being degraded by the radiation environment, being contaminated by the regolith (soil), and if vaporized (and not sealed), it will contaminate the regolith. Thus, it may not be advisable or even possible to use oil because of these limitations. An oil-less, compact traction vehicle drive is a drive designed for use in hostile environments like those that will be encountered on planetary surfaces. Initially, traction roller tests in vacuum were conducted to obtain traction and endurance data needed for designing the drives. From that data, a traction drive was designed that would fit into a prototype lunar rover vehicle, and this design data was used to construct several traction drives. These drives were then tested in air to determine their performance characteristics, and if any final corrections to the designs were necessary. A limitation with current speed reducer systems such as planetary gears and harmonic drives is the high-contact stresses that occur at tooth engagement and in the harmonic drive wave generator interface. These high stresses induce high wear of solid

  9. Superconducting bearings for flywheel applications

    Energy Technology Data Exchange (ETDEWEB)

    Abrahamsen, Asger Bech

    2001-05-01

    A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found on the applications of superconducting bearings in flywheels. (au)

  10. Superconducting bearings for flywheel applications

    DEFF Research Database (Denmark)

    Abrahamsen, A.B.

    2001-01-01

    A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found onthe applications of superconducting bearings...

  11. Cylindrical-confinement-induced phase behaviours of diblock copolymer melts

    International Nuclear Information System (INIS)

    Mei-Jiao, Liu; Shi-Ben, Li; Lin-Xi, Zhang; Xiang-Hong, Wang

    2010-01-01

    The phase behaviours of diblock copolymers under cylindrical confinement are studied in two-dimensional space by using the self-consistent field theory. Several phase parameters are adjusted to investigate the cylindrical-confinement-induced phase behaviours of diblock copolymers. A series of lamella-cylinder mixture phases, such as the mixture of broken-lamellae and cylinders and the mixture of square-lamellae and cylinders, are observed by varying the phase parameters, in which the behaviours of these mixture phases are discussed in the corresponding phase diagrams. Furthermore, the free energies of these mixture phases are investigated to illustrate their evolution processes. Our results are compared with the available observations from the experiments and simulations respectively, and they are in good agreement and provide an insight into the phase behaviours under cylindrical confinement. (cross-disciplinary physics and related areas of science and technology)

  12. The cylindrical GEM detector of the KLOE-2 experiment

    International Nuclear Information System (INIS)

    Bencivenni, G.; Ciambrone, P.; De Lucia, E.; Domenici, D.; Felici, G.; Fermani, P.; Morello, G.; Branchini, P.; Cicco, A. Di; Czerwinski, E.

    2017-01-01

    The KLOE-2 experiment started its data taking campaign in November 2014 with an upgraded tracking system at the DAΦNE electron-positron collider at the Frascati National Laboratory of INFN. The new tracking device, the Inner Tracker, operated together with the KLOE-2 Drift Chamber, has been installed to improve track and vertex reconstruction capabilities of the experimental apparatus. The Inner Tracker is a cylindrical GEM detector composed of four cylindrical triple-GEM detectors, each provided with an X-V strips-pads stereo readout. Although GEM detectors are already used in high energy physics experiments, this device is considered a frontier detector due to its fully-cylindrical geometry: KLOE-2 is the first experiment benefiting of this novel detector technology. Alignment and calibration of this detector will be presented together with its operating performance and reconstruction capabilities.

  13. Errors due to the cylindrical cell approximation in lattice calculations

    Energy Technology Data Exchange (ETDEWEB)

    Newmarch, D A [Reactor Development Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)

    1960-06-15

    It is shown that serious errors in fine structure calculations may arise through the use of the cylindrical cell approximation together with transport theory methods. The effect of this approximation is to overestimate the ratio of the flux in the moderator to the flux in the fuel. It is demonstrated that the use of the cylindrical cell approximation gives a flux in the moderator which is considerably higher than in the fuel, even when the cell dimensions in units of mean free path tend to zero; whereas, for the case of real cells (e.g. square or hexagonal), the flux ratio must tend to unity. It is also shown that, for cylindrical cells of any size, the ratio of the flux in the moderator to flux in the fuel tends to infinity as the total neutron cross section in the moderator tends to zero; whereas the ratio remains finite for real cells. (author)

  14. Buckling localization in a cylindrical panel under axial compression

    DEFF Research Database (Denmark)

    Tvergaard, Viggo; Needleman, A.

    2000-01-01

    Localization of an initially periodic buckling pattern is investigated for an axially compressed elastic-plastic cylindrical panel of the type occurring between axial stiffeners on cylindrical shells. The phenomenon of buckling localization and its analogy with plastic flow localization in tensile...... test specimens is discussed in general. For the cylindrical panel, it is shown that buckling localization develops shortly after a maximum load has been attained, and this occurs for a purely elastic panel as well as for elastic-plastic panels. In a case where localization occurs after a load maximum......, but where subsequently the load starts to increase again, it is found that near the local load minimum, the buckling pattern switches back to a periodic type of pattern. The inelastic material behavior of the panel is described in terms of J(2) corner theory, which avoids the sometimes unrealistically high...

  15. Tight multilattices calculated by extended-cell cylindrization

    Energy Technology Data Exchange (ETDEWEB)

    Segev, M; Carmona, S

    1983-01-01

    Among the common features of advanced LWR concepts are the tightness of lattices and the symbiotic setting of different fuels. Such symbioses often come in the form of multilattices, whose numerically-repeated unit is a configuration of several pins, typically with one pin type at the center and pins of a second type surrounding the center pin. If this extended-cell (EC) unit is cylindricized, then a simple transport calculation of the unit will be possible. If the lattice of such units is tight, there is further an a priori reason to expect the cylindrization to introduce only a small distortion of the true neutron fluxes in the lattice. A strict numerical validation of the EC cylindrization approximation is impractical, but similar validations can be carried out for regular lattices, viewed as being made up of multicell units whose centers are moderators and whose peripheries are fuel pins. In these comparisons the EC cylindrization approximation gives good results.

  16. Cylindrical optical resonators: fundamental properties and bio-sensing characteristics

    Science.gov (United States)

    Khozeymeh, Foroogh; Razaghi, Mohammad

    2018-04-01

    In this paper, detailed theoretical analysis of cylindrical resonators is demonstrated. As illustrated, these kinds of resonators can be used as optical bio-sensing devices. The proposed structure is analyzed using an analytical method based on Lam's approximation. This method is systematic and has simplified the tedious process of whispering-gallery mode (WGM) wavelength analysis in optical cylindrical biosensors. By this method, analysis of higher radial orders of high angular momentum WGMs has been possible. Using closed-form analytical equations, resonance wavelengths of higher radial and angular order WGMs of TE and TM polarization waves are calculated. It is shown that high angular momentum WGMs are more appropriate for bio-sensing applications. Some of the calculations are done using a numerical non-linear Newton method. A perfect match of 99.84% between the analytical and the numerical methods has been achieved. In order to verify the validity of the calculations, Meep simulations based on the finite difference time domain (FDTD) method are performed. In this case, a match of 96.70% between the analytical and FDTD results has been obtained. The analytical predictions are in good agreement with other experimental work (99.99% match). These results validate the proposed analytical modelling for the fast design of optical cylindrical biosensors. It is shown that by extending the proposed two-layer resonator structure analyzing scheme, it is possible to study a three-layer cylindrical resonator structure as well. Moreover, by this method, fast sensitivity optimization in cylindrical resonator-based biosensors has been possible. Sensitivity of the WGM resonances is analyzed as a function of the structural parameters of the cylindrical resonators. Based on the results, fourth radial order WGMs, with a resonator radius of 50 μm, display the most bulk refractive index sensitivity of 41.50 (nm/RIU).

  17. Far-field potentials in cylindrical and rectangular volume conductors.

    Science.gov (United States)

    Dumitru, D; King, J C; Rogers, W E

    1993-07-01

    The occurrence of a transient dipole is one method of producing a far-field potential. This investigation qualitatively defines the characteristics of the near-field and far-field electrical potentials produced by a transient dipole in both cylindrical and rectangular volume conductors. Most body segments of electrophysiologic interest such as arms, legs, thorax, and neck are roughly cylindrical in shape. A centrally located dipole generator produces a nonzero equipotential region which is found to occur along the cylindrical wall at a distance from the dipole of approximately 1.4 times the cylinder's radius and 1.9 times the cylinder's radius for the center of the cylinder. This distance to the equi-potential zone along the surface wall expands but remains less than 3.0 times the cylindrical radius when the dipole is eccentrically placed. The magnitude of the equipotential region resulting from an asymmetrically placed dipole remains identical to that when the dipole is centrally located. This behavior is found to be very similar in rectangular shallow conducting volumes that model a longitudinal slice of the cylinder, thus allowing a simple experimental model of the cylinder to be utilized. Amplitudes of the equipotential region are inversely proportional to the cylindrical or rectangular volume's cross-sectional area at the location of dipolar imbalance. This study predicts that referential electrode montages, when placed at 3.0 times the radius or greater from a dipolar axially aligned far-field generator in cylindrical homogeneous volume conductors, will record only equipotential far-field effects.

  18. Development of new cylindrical magnetrons for industrial use

    International Nuclear Information System (INIS)

    Clayton, B.

    2000-09-01

    A number of alternative techniques were considered and tested with a view to the construction of a cylindrical sputtering device. This device was required to be capable of depositing tribological coatings inside approximately cylindrical substrates of diameters less than 100mm, in an industrial situation. A cylindrical magnetron device was designed, and constructed as a prototype, using a magnetic assembly inside a cylindrical target with outside diameter (o.d.) 40mm. Two alternative magnetic assemblies were tested, and found to have complimentary advantages. The magnetron characteristics of the device were tested, as were key properties (such as adhesion level and hardness) of the coatings deposited. In all cases good results were obtained. A 22mm o.d. device based on the same design was shown to operate, but with less satisfactory characteristics. In an attempt to improve the miniaturised design, the feasibility of gas cooling (rather than water cooling) the cylindrical magnetron was demonstrated. A system incorporating four 40mm o.d. cylindrical magnetrons was designed, constructed and briefly tested. This was intended to prove the feasibility of using a multi-magnetron system to reduce the cost to coat. Its dimensions and design were tailored to an industrially specified engine block. In use the plasma rings formed on the 40mm magnetron target surfaces during operation were found to be of unequal intensities, especially on the shorter magnetron design used in the four-fold system. In an attempt to tackle this problem, a finite element model of the magnetic field generated by the magnetic assembly was built, run and verified. Changes were made to this model, and a new .magnet assembly was built and tested based on the results obtained. This did not lead to a final solution of the problem, but has set bounds within which the solution must lie. (author)

  19. Journal bearing impedance descriptions for rotordynamic applications

    NARCIS (Netherlands)

    Childs, D.W.; Moes, H.; Leeuwen, van H.J.

    1977-01-01

    Bearing impedance vectors are introduced for plain journal bearings which define the bearing reaction force components as a function of the bearing motion. Impedance descriptions are developed directly for the approximate Ocvirk (short) and Sommerfeld (long) bearing solutions. The impedance vector

  20. Energy corrections in pulsed neutron measurements for cylindrical geometry

    International Nuclear Information System (INIS)

    Drozdowicz, K.; Woznicka, U.

    1982-01-01

    A solution of the thermal neutron diffusion equation for a two-region concentric cylindrical system, with a constant neutron flux in the inner medium assumed, is given. The velocity-averaged dynamic parameters for thermal neutrons are used in the method. The corrections due to the diffusion cooling are introduced into the dynamic material buckling and into the velocity distribution of the thermal neutron flux. Detailed relations obtained for a hydrogenous moderator are given. Results of the measurements of the thermal neutron macroscopic absorption cross-sections for the samples in the two-region cylindrical systems are presented. (author)

  1. Confined and interface phonons in combined cylindrical nanoheterosystem

    Directory of Open Access Journals (Sweden)

    O.M.Makhanets

    2006-01-01

    Full Text Available The spectra of all types of phonons existing in a complicated combined nanoheterosystem consisting of three cylindrical quantum dots embedded into the cylindrical quantum wire placed into vacuum are studied within the dielectric continuum model. It is shown that there are confined optical (LO and interface phonons of two types: top surface optical (TSO and side surface optical (SSO modes of vibration in such a nanosystem. The dependences of phonon energies on the quasiwave numbers and geometrical parameters of quantum dots are investigated and analysed.

  2. The magnetic properties of the hollow cylindrical ideal remanence magnet

    DEFF Research Database (Denmark)

    Bjørk, Rasmus

    2016-01-01

    We consider the magnetic properties of the hollow cylindrical ideal remanence magnet. This magnet is the cylindrical permanent magnet that generates a uniform field in the cylinder bore, using the least amount of magnetic energy to do so. The remanence distribution of this magnet is derived...... and the generated field is compared to that of a Halbach cylinder of equal dimensions. The ideal remanence magnet is shown in most cases to generate a significantly lower field than the equivalent Halbach cylinder, although the field is generated with higher efficiency. The most efficient Halbach cylinder is shown...... to generate a field exactly twice as large as the equivalent ideal remanence magnet....

  3. Two-dimensional collapse calculations of cylindrical clouds

    International Nuclear Information System (INIS)

    Bastien, P.; Mitalas, R.

    1979-01-01

    A two-dimensional hydrodynamic computer code has been extensively modified and expanded to study the collapse of non-rotating interstellar clouds. The physics and the numerical methods involved are discussed. The results are presented and discussed in terms of the Jeans number. The critical Jeans number for collapse of non-rotating cylindrical clouds whose length is the same as their diameter is 1.00. No evidence for fragmentation has been found for these clouds, but fragmentation seems quite likely for more elongated cylindrical clouds. (author)

  4. Gravitational collapse of a cylindrical null shell in vacuum

    Directory of Open Access Journals (Sweden)

    S. Khakshournia

    2008-03-01

    Full Text Available   Barrabès-Israel null shell formalism is used to study the gravitational collapse of a thin cylindrical null shell in vacuum. In general the lightlike matter shell whose history coincides with a null hypersurface is characterized by a surface energy density. In addition, a gravitational impulsive wave is present on this null hypersurface whose generators admit both the shear and expansion. In the case of imposing the cylindrical flatness the surface energy-momentum tensor of the matter shell on the null hypersurface vanishes and the null hyper- surface is just the history of the gravitational wave .

  5. Analytic descriptions of cylindrical electromagnetic waves in a nonlinear medium

    Science.gov (United States)

    Xiong, Hao; Si, Liu-Gang; Yang, Xiaoxue; Wu, Ying

    2015-01-01

    A simple but highly efficient approach for dealing with the problem of cylindrical electromagnetic waves propagation in a nonlinear medium is proposed based on an exact solution proposed recently. We derive an analytical explicit formula, which exhibiting rich interesting nonlinear effects, to describe the propagation of any amount of cylindrical electromagnetic waves in a nonlinear medium. The results obtained by using the present method are accurately concordant with the results of using traditional coupled-wave equations. As an example of application, we discuss how a third wave affects the sum- and difference-frequency generation of two waves propagation in the nonlinear medium. PMID:26073066

  6. Spherical and cylindrical particle resonator as a cloak system

    Science.gov (United States)

    Minin, I. V.; Minin, O. V.; Eremeev, A. I.; Tseplyaev, I. S.

    2018-05-01

    The concept of dielectric spherical or cylindrical particle in resonant mode as a cloak system is offered. In fundamental modes (modes with the smallest volume correspond to |m| = l, and s = 1) the field is concentrated mostly in the equatorial plane and at the surface of the sphere. Thus under resonance modes, such perturbation due to cuboid particle inserted in the spherical or cylindrical particle has almost no effect on the field forming resonance regardless of the value of internal particle material (defect) as long as this material does not cover the region where resonance takes place.

  7. Experiments on cylindrically converging blast waves in atmospheric air

    Science.gov (United States)

    Matsuo, Hideo; Nakamura, Yuichi

    1980-06-01

    Cylindrically converging blast waves have been produced in normal atmospheric conditions by the detonation of the explosives, pentaerythritoltetranitrate, (PETN), over cylindrical surfaces. The shocks generated in this way are so strong that the fronts propagating through the air become luminous of themselves. The production and the propagation of the shocks have been monitored with a framing camera and a streak camera, and the time-space relations of the shock propagations have been determined using an electrical ionization probing system. The results have shown that the trajectory of the shock fronts near the axis of the cylinder can be approximately represented by the Guderley's formula.

  8. Metallurgical Evaluation of the Five-Inch Cylindrical Induction Melter

    International Nuclear Information System (INIS)

    Imrich, K.J.

    2000-01-01

    A metallurgical evaluation of the 5-inch cylindrical induction melter (CIM) vessel was performed by the Materials Technology Section to evaluate the metallurgical condition after operating for approximately 375 hours at 1400 to 1500 Degrees Celsius during a 2 year period. Results indicate that wall thinning and significant grain growth occurred in the lower portion of the conical section and the drain tube. No through-wall penetrations were found in the cylindrical and conical sections of the CIM vessel and only one leak site was identified in the drain tube. Failure of the drain tube was associated with a localized over heating and intercrystalline fracture

  9. Fabrication of cermet bearings for the control system of a high temperature lithium cooled nuclear reactor

    Science.gov (United States)

    Yacobucci, H. G.; Heestand, R. L.; Kizer, D. E.

    1973-01-01

    The techniques used to fabricate cermet bearings for the fueled control drums of a liquid metal cooled reference-design reactor concept are presented. The bearings were designed for operation in lithium for as long as 5 years at temperatures to 1205 C. Two sets of bearings were fabricated from a hafnium carbide - 8-wt. % molybdenum - 2-wt. % niobium carbide cermet, and two sets were fabricated from a hafnium nitride - 10-wt. % tungsten cermet. Procedures were developed for synthesizing the material in high purity inert-atmosphere glove boxes to minimize oxygen content in order to enhance corrosion resistance. Techniques were developed for pressing cylindrical billets to conserve materials and to reduce machining requirements. Finishing was accomplished by a combination of diamond grinding, electrodischarge machining, and diamond lapping. Samples were characterized in respect to composition, impurity level, lattice parameter, microstructure and density.

  10. Acute, fatal Sarcocystis calchasi-associated hepatitis in Roller pigeons (Columba livia f. dom.) at Philadelphia Zoo.

    Science.gov (United States)

    Trupkiewicz, J G; Calero-Bernal, R; Verma, S K; Mowery, J; Davison, S; Habecker, P; Georoff, T A; Ialeggio, D M; Dubey, J P

    2016-01-30

    Four Roller pigeons (Columba livia f. dom.) at the Philadelphia Zoo died suddenly. Necropsy examination revealed macroscopic hepatitis. Microscopically, the predominant lesions were in liver, characterized with necrosis and mixed cell inflammatory response. Sarcocystis calchasi-like schizonts and free merozoites were identified in liver. Transmission electron microscopy confirmed that schizonts were in hepatocytes. A few schizonts were in spleen. PCR using S. calchasi-specific primers confirmed the diagnosis. Neither lesions nor protozoa were found in brain and muscles. This is the first report of acute visceral S. calchasi-associated sarcocystosis in naturally infected avian hosts. Published by Elsevier B.V.

  11. Eastern slopes grizzly bear project

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-01-01

    The cumulative effects of human activities on the grizzly bears in the central Canadian Rockies are not well known. As a result, a project was initiated in 1994 to address the urgent requirement for accurate scientific information on the habitat and populations of grizzly bears in the area of the Banff National Park and Kananaskis Country. This area is probably the most heavily used and developed area where the grizzly still survives. The information gathered throughout the course of this study will be used to better protect and manage the bears and other sensitive carnivores in the region. Using telemetry, researchers are monitoring 25 grizzly bears which were radio-collared in a 22,000 square-kilometer area in the upper Bow Valley drainage of the eastern Alberta slopes. The researchers involved in the project are working with representatives from Husky Oil and Talisman Energy on the sound development of the Moose Mountain oil and gas field without adversely affecting the grizzly bear population. Information collected over seven years indicated that the grizzly bears have few and infrequent offspring. Using the information gathered so far, the location of the Moose Mountain to Jumping Pound pipeline was carefully selected, since the bears recover very slowly from high mortality, and also considering that the food and cover had already been compromised by the high number of roads, trails and other human activities in the area. The status of the population and habitat of the grizzly bear will be assessed upon the conclusion of the field research phase in 2001. Models will be updated using the data obtained during eight years and will assist in the understanding of complex variables that affect grizzly bears.

  12. EFFECT OF BEARING MACROGEOMETRY ON BEARING PERFORMANCE IN ELASTOHYDRODYNAMIC LUBRICATION

    Directory of Open Access Journals (Sweden)

    Emin GÜLLÜ

    2000-01-01

    Full Text Available During manufacturing, ideal dimension and mutual positioning of machine elements proposed in project desing can be achieved only within certain range of tolerances. These tolerances, being classified in two groups, related to micro and macro geometry of machine elements, don't have to effect the functioning of these elements. So, as for all machine elements, investigation of the effects of macro and micro tolerances for journal bearings is important. In this study, we have investigated the effect of macro geometric irregularities of journal bearings on performance characteristics. In this regard, we have studied the change of bearing performance in respect to deviation from ideal circle for an elliptic shaft with small ovality rolling in circular journal bearing.

  13. Superconducting-electromagnetic hybrid bearing using YBCO bulk blocks for passive axial levitation

    Science.gov (United States)

    Nicolsky, R.; de Andrade, R., Jr.; Ripper, A.; David, D. F. B.; Santisteban, J. A.; Stephan, R. M.; Gawalek, W.; Habisreuther, T.; Strasser, T.

    2000-06-01

    A superconducting/electromagnetic hybrid bearing has been designed using active radial electromagnetic positioning and a superconducting passive axial levitator. This bearing has been tested for an induction machine with a vertical shaft. The prototype was conceived as a four-pole, two-phase induction machine using specially designed stator windings for delivering torque and radial positioning simultaneously. The radial bearing uses four eddy-current sensors, displaced 90° from each other, for measuring the shaft position and a PID control system for feeding back the currents. The stator windings have been adapted from the ones of a standard induction motor. The superconducting axial bearing has been assembled with commercial NdFeB permanent magnets and a set of seven top-seeded-melt-textured YBCO large-grain cylindrical blocks. The bearing set-up was previously simulated by a finite element method for different permanent magnet-superconductor block configurations. The stiffness of the superconducting axial bearing has been investigated by measuring by a dynamic method the vertical and transversal elastic constants for different field cooling processes. The resulting elastic constants show a linear dependence on the air gap, i.e. the clearance between the permanent magnet assembly and the set of superconducting large-grain blocks, which is dependent on cooling distance.

  14. Non-contacting "snubber bearing" for passive magnetic bearing systems

    Science.gov (United States)

    Post, Richard F

    2017-08-22

    A new non-contacting magnetic "snubber" bearing is provided for application to rotating systems such as vehicular electromechanical battery systems subject to frequent accelerations. The design is such that in the equilibrium position the drag force of the snubber is very small (milliwatts). However in a typical case, if the rotor is displaced by as little as 2 millimeters a large restoring force is generated without any physical contact between the stationary and rotating parts of the snubber bearing.

  15. Bears, Big and Little. Young Discovery Library Series.

    Science.gov (United States)

    Pfeffer, Pierre

    This book is written for children 5 through 10. Part of a series designed to develop their curiosity, fascinate them and educate them, this volume describes: (1) the eight species of bears, including black bear, brown bear, grizzly bear, spectacled bear, sun bear, sloth bear, polar bear, and giant panda; (2) geographical habitats of bears; (3)…

  16. Magnetization curves for general cylindrical samples in a transverse ...

    Indian Academy of Sciences (India)

    complexity associated with the task of determining and studying the movement of the flux- front as the flux ... a volume current density causing the flux-front to move by an appropriate amount. Since the flux-front does ... Let us consider an infinite cylindrical sample with its axis along the z-axis and its cross- section bounded ...

  17. Acoustic characteristics of sand sediment with circular cylindrical pores

    International Nuclear Information System (INIS)

    Roh, Heui-Seol; Lee, Kang-Il; Yoon, Suk-Wang

    2004-01-01

    The acoustic pressure transmission coefficient and the phase velocity are experimentally measured as functions of the frequency and the porosity in sand sediment slabs with circular cylindrical pores filled with water and air. They are also theoretically estimated with the modified Biot-Attenborough (MBA) model, which uses a separate treatment of the viscous and the thermal effects in a non-rigid porous medium with water- and air-filled cylindrical pores. In this study, the fast (first kind) wave and the slow (second kind) wave are not separated in the transmitted signals through a sediment slab without the circular cylindrical pores, but they are separated in the transmitted signals through a sediment slab with pores. Both the phase velocities and the transmission coefficients of the fast wave and the slow wave in the sediment slabs with water- and air-filled cylindrical pores are sensitive to the air and the water porosities. It is proposed that the fast and the slow waves have opposite behaviors for several acoustic characteristics. The generalized tortuosity factor and the dynamic shape factor are introduced from the acoustic characteristics of the fast wave. The experimental results show reasonable agreement with the theoretical results estimated with the MBA model. These results suggest the possibility of predicting the acoustic characteristics of a sediment as functions of arbitrary water and air porosities. This study may also be applicable to understanding acoustic wave propagations in a bubbly liquid sediment for underwater applications and in cancellous bone for the diagnosis of osteoporosis.

  18. An approximate solution for spherical and cylindrical piston problem

    Indian Academy of Sciences (India)

    the growth and decay of shock strengths for spherical and cylindrical pistons starting from a non-zero ... conditions at an appropriate level, a new theory of shock dynamics (NTSD) has been proposed (Ravindran and ..... sive, its packing density etc. which are not included in our mathematical formulation, it may explain the ...

  19. Coupled dilaton and electromagnetic field in cylindrically symmetric ...

    Indian Academy of Sciences (India)

    An exact solution is obtained for coupled dilaton and electromagnetic field in a cylindrically symmetric spacetime where an axial magnetic field as well as a radial electric field both are present. Depending on the choice of the arbitrary constants our solution reduces either to dilatonic gravity with pure electric field or to that ...

  20. ELECTROMAGNETIC FIELDS IN CYLINDRICAL INDUCTION INDUCTOR SYSTEM WITH MASSIVE SHIELD

    Directory of Open Access Journals (Sweden)

    D. Piskun

    2010-12-01

    Full Text Available The processes in a cylindrical induction inductor system with a massive additional non-magnetic shield and a thin ferromagnetic sheet blank are considered and the formula for induced currents and the strength of excited fields have been obtained.