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Sample records for spiral bevel gears

  1. Analisa Kekuatan Spiral Bevel Gear Dengan Variasi Sudut Spiral Menggunakan Metode Elemen Hingga

    OpenAIRE

    Deta Rachmat Andika; Agus Sigit Pramono

    2017-01-01

    Seiring perkembangan zaman,  teknologi roda gigi dituntut untuk mampu mentransmisikan daya yang besar dengan efisiensi yang besar pula. Pada jenis intersecting shaft gear, tipe roda gigi payung spiral (spiral bevel gear)  merupakan perkembangan dari roda gigi payung bergigi lurus (straight bevel gear). Kelebihan dari spiral bevel gear antara  lain adalah kemampuan transmisi daya dan efisiensi yang lebih besar pada geometri yang sama serta tidak terlalu berisik. Akan tetapi spiral bevel gear j...

  2. Recent Advances in the Analysis of Spiral Bevel Gears

    Science.gov (United States)

    Handschuh, Robert F.

    1997-01-01

    A review of recent progress for the analysis of spiral bevel gears will be described. The foundation of this work relies on the description of the gear geometry of face-milled spiral bevel gears via the approach developed by Litvin. This methodology was extended by combining the basic gear design data with the manufactured surfaces using a differential geometry approach, and provides the data necessary for assembling three-dimensional finite element models. The finite element models have been utilized to conduct thermal and structural analysis of the gear system. Examples of the methods developed for thermal and structural/contact analysis are presented.

  3. Advanced Manufacture of Spiral Bevel and Hypoid Gears

    Directory of Open Access Journals (Sweden)

    Vilmos Simon

    2016-11-01

    Full Text Available In this study, an advanced method for the manufacture of spiral bevel and hypoid gears on CNC hypoid generators is proposed. The optmal head-cutter geometry and machine tool settings are determined to introduce the optimal tooth surface modifications into the teeth of spiral bevel and hypoid gears. The aim of these tooth surface modifications is to simultaneously reduce the tooth contact pressure and the transmission errors, to maximize the EHD load carrying capacity of the oil film, and to minimize power losses in the oil film. The proposed advanced method for the manufacture of spiral bevel and hypoid gears is based on machine tool setting variation on the cradle-type generator conducted by optimal polynomial functions and on the use of a CNC hypoid generator. An algorithm is developed for the execution of motions on the CNC hypoid generator using the optimal relations on the cradle-type machine. Effectiveness of the method was demonstrated by using spiral bevel and hypoid gear examples. Significant improvements in the operating characteristics of the gear pairs are achieved.

  4. New generation methods for spur, helical, and spiral-bevel gears

    Science.gov (United States)

    Litvin, F. L.; Tsung, W.-J.; Coy, J. J.; Handschuh, R. F.; Tsay, C.-B. P.

    1987-01-01

    New methods for generating spur, helical, and spiral-bevel gears are proposed. These methods provide the gears with conjugate gear tooth surfaces, localized bearing contact, and reduced sensitivity to gear misalignment. Computer programs have been developed for simulating gear meshing and bearing contact.

  5. Evaluation of Low-Noise, Improved-Bearing-Contact Spiral Bevel Gears

    National Research Council Canada - National Science Library

    Lewicki, Davide

    2003-01-01

    .... Experimental tests were performed on the OH-58D helicopter main-rotor transmission in the NASA Glenn 500-hp Helicopter Transmission Test Stand Low-noise, improved-bearing- contact spiral-bevel gears...

  6. Tooth Fracture Detection in Spiral Bevel Gears System by Harmonic Response Based on Finite Element Method

    OpenAIRE

    Chen, Yuan; Zhu, Rupeng; Jin, Guanghu; Xiong, Yeping

    2017-01-01

    Spiral bevel gears occupy several advantages such as high contact ratio, strong carrying capacity, and smooth operation, which become one of the most widely used components in high-speed stage of the aeronautical transmission system. Its dynamic characteristics are addressed by many scholars. However, spiral bevel gears, especially tooth fracture occurrence and monitoring, are not to be investigated, according to the limited published issues. Therefore, this paper establishes a three-dimensio...

  7. Five-Axis Milling of Large Spiral Bevel Gears: Toolpath Definition, Finishing, and Shape Errors

    Directory of Open Access Journals (Sweden)

    Álvaro Álvarez

    2018-05-01

    Full Text Available In this paper, a five-axis machining process is analyzed for large spiral-bevel gears, an interesting process for one-of-kind manufacturing. The work is focused on large sized spiral bevel gears manufacturing using universal multitasking machines or five-axis milling centers. Different machining strategies, toolpath patterns, and parameters are tested for both gear roughing and finishing operations. Machining time, tools’ wear, and gear surface are analyzed in order to determine which are the best strategies and parameters for large modulus gear manufacturing on universal machines. The case study results are discussed in the last section, showing the capacity of a universal five-axis milling for this niche. Special attention was paid to the possible affectations of the metal surfaces, since gear durability is very sensitive to thermo-mechanical damage, affected layers, and flank gear surface state.

  8. Integrating Condition Indicators and Usage Parameters for Improved Spiral Bevel Gear Health Monitoring

    Science.gov (United States)

    Dempsey, Paula J.; Handschuh, Robert F.; Delgado, Irebert, R.

    2013-01-01

    The objective of this study was to illustrate the importance of combining Health Usage Monitoring Systems (HUMS) data with usage monitoring system data when detecting rotorcraft transmission health. Three gear sets were tested in the NASA Glenn Spiral Bevel Gear Fatigue Rig. Damage was initiated and progressed on the gear and pinion teeth. Damage progression was measured by debris generation and documented with inspection photos at varying torque values. A contact fatigue analysis was applied to the gear design indicating the effect temperature, load and reliability had on gear life. Results of this study illustrated the benefits of combining HUMS data and actual usage data to indicate progression of damage for spiral bevel gears.

  9. Effects of Geometry Design Parameters on the Static Strength and Dynamics for Spiral Bevel Gear

    Directory of Open Access Journals (Sweden)

    Zhiheng Feng

    2017-01-01

    Full Text Available Considering the geometry design parameters, a quasi-static mesh model of spiral bevel gears was established and the mesh characteristics were computed. Considering the time-varying effects of mesh points, mesh force, line-of-action vector, mesh stiffness, transmission error, friction force direction, and friction coefficient, a nonlinear lumped parameter dynamic model was developed for the spiral bevel gear pair. Based on the mesh model and the nonlinear dynamic model, the effects of main geometry parameters on the contact and bending strength were analyzed. Also, the effects on the dynamic mesh force and dynamic transmission error were investigated. Results show that higher value for the pressure angle, root fillet radius, and the ratio of tooth thickness tend to improve the contact and bending strength and to reduce the risk of tooth fracture. Improved gears have a better vibration performance in the targeted frequency range. Finally, bench tests for both types of spiral bevel gears were performed. Results show that the main failure mode is the tooth fracture and the life was increased a lot for the spiral bevel gears with improved geometry parameters compared to the original design.

  10. A Procedure for 3-D Contact Stress Analysis of Spiral Bevel Gears

    Science.gov (United States)

    Kumar, A.; Bibel, G.

    1994-01-01

    Contact stress distribution of spiral bevel gears using nonlinear finite element static analysis is presented. Procedures have been developed to solve the nonlinear equations that identify the gear and pinion surface coordinates based on the kinematics of the cutting process and orientate the pinion and the gear in space to mesh with each other. Contact is simulated by connecting GAP elements along the intersection of a line from each pinion point (parallel to the normal at the contact point) with the gear surface. A three dimensional model with four gear teeth and three pinion teeth is used to determine the contact stresses at two different contact positions in a spiral bevel gearset. A summary of the elliptical contact stress distribution is given. This information will be helpful to helicopter and aircraft transmission designers who need to minimize weight of the transmission and maximize reliability.

  11. Tooth Fracture Detection in Spiral Bevel Gears System by Harmonic Response Based on Finite Element Method

    Directory of Open Access Journals (Sweden)

    Yuan Chen

    2017-01-01

    Full Text Available Spiral bevel gears occupy several advantages such as high contact ratio, strong carrying capacity, and smooth operation, which become one of the most widely used components in high-speed stage of the aeronautical transmission system. Its dynamic characteristics are addressed by many scholars. However, spiral bevel gears, especially tooth fracture occurrence and monitoring, are not to be investigated, according to the limited published issues. Therefore, this paper establishes a three-dimensional model and finite element model of the Gleason spiral bevel gear pair. The model considers the effect of tooth root fracture on the system due to fatigue. Finite element method is used to compute the mesh generation, set the boundary condition, and carry out the dynamic load. The harmonic response spectra of the base under tooth fracture are calculated and the influence of main parameters on monitoring failure is investigated as well. The results show that the change of torque affects insignificantly the determination of whether or not the system has tooth fracture. The intermediate frequency interval (200 Hz–1000 Hz is the best interval to judge tooth fracture occurrence. The best fault test region is located in the working area where the system is going through meshing. The simulation calculation provides a theoretical reference for spiral bevel gear system test and fault diagnosis.

  12. Mathematical models for the synthesis and optimization of spiral bevel gear tooth surfaces. [for helicopter transmissions

    Science.gov (United States)

    Litvin, F. L.; Rahman, P.; Goldrich, R. N.

    1982-01-01

    The geometry of spiral bevel gears and to their rational design are studied. The nonconjugate tooth surfaces of spiral bevel gears are, in theory, replaced (or approximated) by conjugated tooth surfaces. These surfaces can be generated by two conical surfaces, and by a conical surface and a revolution. Although these conjugated tooth surfaces are simpler than the actual ones, the determination of their principal curvatures and directions is still a complicated problem. Therefore, a new approach, to the solution of these is proposed. Direct relationships between the principal curvatures and directions of the tool surface and those of the generated gear surface are obtained. With the aid of these analytical tools, the Hertzian contact problem for conjugate tooth surfaces can be solved. These results are useful in determining compressive load capacity and surface fatigue life of spiral bevel gears. A general theory of kinematical errors exerted by manufacturing and assembly errors is developed. This theory is used to determine the analytical relationship between gear misalignments and kinematical errors. This is important to the study of noise and vibration in geared systems.

  13. Remanufacturing the Pinion: An Application of a New Design Method for Spiral Bevel Gears

    Directory of Open Access Journals (Sweden)

    Baozhen Lei

    2014-03-01

    Full Text Available Damages of a large spiral bevel gear drive as used in heavy industry typically affect the pinion. Even if the gear still could be used, the complete pair has to be changed. This leads to long off times, high costs, and unnecessary waste. This paper applies a recent design technology for spiral bevel gears to the production of a replacement pinion for the sake of energy saving, reduction of costs and off times, and for the realization of green engineering. The process involves the following steps. First, the real tool surface of the gear is measured by a CMM. Based on the new design method, the tooth surface of the mating pinion is derived from this discrete point cloud. In order to improve the meshing performance, the resulting surface of the pinion is modified in the third step. Finally, the pinion is produced on a CNC machining center. In contrast to other approaches, none of these steps needs the parameters of the special machine tool defining the original gear pair. It is worth noting that our technology can also be profitable to gain more freedom in the design of new gear pairs.

  14. Manual for automatic generation of finite element models of spiral bevel gears in mesh

    Science.gov (United States)

    Bibel, G. D.; Reddy, S.; Kumar, A.

    1994-01-01

    The goal of this research is to develop computer programs that generate finite element models suitable for doing 3D contact analysis of faced milled spiral bevel gears in mesh. A pinion tooth and a gear tooth are created and put in mesh. There are two programs: Points.f and Pat.f to perform the analysis. Points.f is based on the equation of meshing for spiral bevel gears. It uses machine tool settings to solve for an N x M mesh of points on the four surfaces, pinion concave and convex, and gear concave and convex. Points.f creates the file POINTS.OUT, an ASCI file containing N x M points for each surface. (N is the number of node points along the length of the tooth, and M is nodes along the height.) Pat.f reads POINTS.OUT and creates the file tl.out. Tl.out is a series of PATRAN input commands. In addition to the mesh density on the tooth face, additional user specified variables are the number of finite elements through the thickness, and the number of finite elements along the tooth full fillet. A full fillet is assumed to exist for both the pinion and gear.

  15. Computerized Design of Low-noise Face-milled Spiral Bevel Gears

    Science.gov (United States)

    Litvin, Faydor L.; Zhang, YI; Handschuh, Robert F.

    1994-01-01

    An advanced design methodology is proposed for the face-milled spiral bevel gears with modified tooth surface geometry that provides a reduced level of noise and has a stabilized bearing contact. The approach is based on the local synthesis of the gear drive that provides the 'best' machine-tool settings. The theoretical aspects of the local synthesis approach are based on the application of a predesigned parabolic function for absorption of undesirable transmission errors caused by misalignment and the direct relations between principal curvatures and directions for mating surfaces. The meshing and contact of the gear drive is synthesized and analyzed by a computer program. The generation of gears with the proposed geometry design can be accomplished by application of existing equipment. A numerical example that illustrates the proposed theory is presented.

  16. Dynamic analysis of spiral bevel and hypoid gears with high-order transmission errors

    Science.gov (United States)

    Yang, J. J.; Shi, Z. H.; Zhang, H.; Li, T. X.; Nie, S. W.; Wei, B. Y.

    2018-03-01

    A new gear surface modification methodology based on curvature synthesis is proposed in this study to improve the transmission performance. The generated high-order transmission error (TE) for spiral bevel and hypoid gears is proved to reduce the vibration of geared-rotor system. The method is comprised of the following steps: Firstly, the fully conjugate gear surfaces with pinion flank modified according to the predesigned relative transmission movement are established based on curvature correction. Secondly, a 14-DOF geared-rotor system model considering backlash nonlinearity is used to evaluate the effect of different orders of TE on the dynamic performance a hypoid gear transmission system. For case study, numerical simulation is performed to illustrate the dynamic response of hypoid gear pair with parabolic, fourth-order and sixth-order transmission error derived. The results show that the parabolic TE curve has higher peak to peak amplitude compared to the other two types of TE. Thus, the excited dynamic response also shows larger amplitude at response peaks. Dynamic responses excited by fourth and sixth order TE also demonstrate distinct response components due to their different TE period which is expected to generate different sound quality or other acoustic characteristics.

  17. Modeling and Analysis of Deformation for Spiral Bevel Gear in Die Quenching Based on the Hardenability Variation

    Science.gov (United States)

    Zhang, Yingtao; Wang, Gang; Shi, Wankai; Yang, Lin; Li, Zhichao

    2017-07-01

    Spiral bevel gears are widely used to transmit energy between intersecting axes. The strength and fatigue life of the gears are improved by carburizing and quenching. A die quenching process is used to control the deformation of the gear. The deformation is determined by the variations in the hardenability for a certain die quenching process. The relationship between hardenability, phase transformation and deformation needs to be studied to minimize deformation during the adjustment of the die quenching process parameters. In this paper, material properties for 22CrMoH steel are determined by the results of Jominy tests, dilatometry experiments and static mechanical property tests. The material models were built based on testing results under the consideration of hardenability variation. An finite element analysis model was developed to couple the phase transformation and deformation history of the complete carburizing and die quenching process for the spiral bevel gears. The final microstructures in the gear were bainite for low hardenability steel and a mixture of bainite and ferrite for high hardenability steel. The largest buckling deformation at the gear bottom surface is 0.375 mm at the outer circle for the low hardenability gear and 0.091 mm at the inner circle for the high hardenability gear.

  18. Investigation of Spiral Bevel Gear Condition Indicator Validation via AC-29-2C Using Fielded Rotorcraft HUMS Data

    Science.gov (United States)

    Dempsey, Paula J.; Wade, Daniel R.; Antolick, Lance J.; Thomas, Josiah

    2014-01-01

    This report presents the analysis of gear condition indicator data collected on a helicopter when damage occurred in spiral bevel gears. The purpose of the data analysis was to use existing in-service helicopter HUMS flight data from faulted spiral bevel gears as a Case Study, to better understand the differences between HUMS data response in a helicopter and a component test rig, the NASA Glenn Spiral Bevel Gear Fatigue Rig. The reason spiral bevel gear sets were chosen to demonstrate differences in response between both systems was the availability of the helicopter data and the availability of a test rig that was capable of testing spiral bevel gear sets to failure. The objective of the analysis presented in this paper was to re-process helicopter HUMS data with the same analysis techniques applied to the spiral bevel rig test data. The damage modes experienced in the field were mapped to the failure modes created in the test rig. A total of forty helicopters were evaluated. Twenty helicopters, or tails, experienced damage to the spiral bevel gears in the nose gearbox. Vibration based gear condition indicators data was available before and after replacement. The other twenty tails had no known anomalies in the nose gearbox within the time frame of the datasets. These twenty tails were considered the baseline dataset. The HUMS gear condition indicators evaluated included gear condition indicators (CI) Figure of Merit 4 (FM4), Root Mean Square (RMS) or Diagnostic Algorithm 1 (DA1) and +/- 3 Sideband Index (SI3). Three additional condition indicators, not currently calculated on-board, were calculated from the archived data. These three indicators were +/- 1 Sideband Index (SI1), the DA1 of the difference signal (DiffDA1) and the peak-to-peak of the difference signal (DP2P). Results found the CI DP2P, not currently available in the on-board HUMS, performed the best, responding to varying levels of damage on thirteen of the fourteen helicopters evaluated. Two

  19. Investigation of Spiral Bevel Gear Condition Indicator Validation Via AC-29-2C Using Damage Progression Tests

    Science.gov (United States)

    Dempsey, Paula J.

    2014-01-01

    This report documents the results of spiral bevel gear rig tests performed under a NASA Space Act Agreement with the Federal Aviation Administration (FAA) to support validation and demonstration of rotorcraft Health and Usage Monitoring Systems (HUMS) for maintenance credits via FAA Advisory Circular (AC) 29-2C, Section MG-15, Airworthiness Approval of Rotorcraft (HUMS) (Ref. 1). The overarching goal of this work was to determine a method to validate condition indicators in the lab that better represent their response to faults in the field. Using existing in-service helicopter HUMS flight data from faulted spiral bevel gears as a "Case Study," to better understand the differences between both systems, and the availability of the NASA Glenn Spiral Bevel Gear Fatigue Rig, a plan was put in place to design, fabricate and test comparable gear sets with comparable failure modes within the constraints of the test rig. The research objectives of the rig tests were to evaluate the capability of detecting gear surface pitting fatigue and other generated failure modes on spiral bevel gear teeth using gear condition indicators currently used in fielded HUMS. Nineteen final design gear sets were tested. Tables were generated for each test, summarizing the failure modes observed on the gear teeth for each test during each inspection interval and color coded based on damage mode per inspection photos. Gear condition indicators (CI) Figure of Merit 4 (FM4), Root Mean Square (RMS), +/- 1 Sideband Index (SI1) and +/- 3 Sideband Index (SI3) were plotted along with rig operational parameters. Statistical tables of the means and standard deviations were calculated within inspection intervals for each CI. As testing progressed, it became clear that certain condition indicators were more sensitive to a specific component and failure mode. These tests were clustered together for further analysis. Maintenance actions during testing were also documented. Correlation coefficients were

  20. A Method for Determining Spiral-Bevel Gear Tooth Geometry for Finite Element Analysis

    Science.gov (United States)

    1991-08-01

    to0itated Ins.pecttion aind Pceci.i’i (;Irtdtite Lit Spiral Betel pp 1i7 33;4. Gear.. NA.SA- CR 4083.AASCONI FR 87 -C’ 1 1,I98-1 4 ((taint. SB H...ti-io..n. NASA 1t) 27115. A .NSC( (Nt IR [,It\\. 1ii. 1... ei al, Nietlid 1h1 irCiciteatin Lit Spiral Betel Gear.. W%’itl 86 (’-42. 1987. C𔃻...P.C , Silrlace Geiiiitetr. ’I StraiLght lintl Spiril A.SM1 ilpaper X4-DET:- 169. Oct. 1984 Betel Gear... j NCIec trait.. Nutittlat. Dc... .o iIlt

  1. Enhanced Computer Aided Simulation of Meshing and Contact With Application for Spiral Bevel Gear Drives

    National Research Council Canada - National Science Library

    Litvin, F

    1999-01-01

    An integrated tooth contact analysis (TCA) computer program for the simulation of meshing and contact of gear drives that calculates transmission errors and shift of hearing contact for misaligned gear drives has been developed...

  2. Investigation of Spiral Bevel Gear Condition Indicator Validation via AC-29-2C Combining Test Rig Damage Progression Data with Fielded Rotorcraft Data

    Science.gov (United States)

    Dempsey, Paula J.

    2015-01-01

    This is the final of three reports published on the results of this project. In the first report, results were presented on nineteen tests performed in the NASA Glenn Spiral Bevel Gear Fatigue Test Rig on spiral bevel gear sets designed to simulate helicopter fielded failures. In the second report, fielded helicopter HUMS data from forty helicopters were processed with the same techniques that were applied to spiral bevel rig test data. Twenty of the forty helicopters experienced damage to the spiral bevel gears, while the other twenty helicopters had no known anomalies within the time frame of the datasets. In this report, results from the rig and helicopter data analysis will be compared for differences and similarities in condition indicator (CI) response. Observations and findings using sub-scale rig failure progression tests to validate helicopter gear condition indicators will be presented. In the helicopter, gear health monitoring data was measured when damage occurred and after the gear sets were replaced at two helicopter regimes. For the helicopters or tails, data was taken in the flat pitch ground 101 rotor speed (FPG101) regime. For nine tails, data was also taken at 120 knots true airspeed (120KTA) regime. In the test rig, gear sets were tested until damage initiated and progressed while gear health monitoring data and operational parameters were measured and tooth damage progression documented. For the rig tests, the gear speed was maintained at 3500RPM, a one hour run-in was performed at 4000 in-lb gear torque, than the torque was increased to 8000 in-lbs. The HUMS gear condition indicator data evaluated included Figure of Merit 4 (FM4), Root Mean Square (RMS) or Diagnostic Algorithm 1(DA1), + 3 Sideband Index (SI3) and + 1 Sideband Index (SI1). These were selected based on their sensitivity in detecting contact fatigue damage modes from analytical, experimental and historical helicopter data. For this report, the helicopter dataset was reduced to

  3. Bevel gear driver and method having torque limit selection

    Science.gov (United States)

    Cook, Joseph S., Jr.

    1994-08-01

    This invention comprises a torque drive mechanism utilizing axially translatable, mutually engageable transmission members having mating crown gears, driven and driving members with a three-element drive train being biased together by resilient means or by a fluid actuator system, the apparatus being operable to transmit a precisely controlled degree of torque to a driven member. The apparatus is applicable for use in hand tools and as a replacement for impact torque drivers, torque wrenches, motorized screw drivers, or the like, wherein the applied torque must be precisely controlled or limited. The bevel torque drive includes a drive gear which is axially displaceable and rotatable within cylindrical driver housing, a rotatable intermediate gear, and an output gear. Key rotationally secures displaceable gear with respect to input shaft but permits axial movement therebetween. A thrust bearing is preferably connected to the lower end of shaft for support to reduce play and friction between shaft and a transmission joint disc during rotation of the gear train. Coaxially mounted coiled spring is footed against displaceable gear for biasing the displaceable gear toward and into engagement with the intermediate gear for driving intermediate gear and output gear. Torque control is achieved by the use of straight or spiral beveled gears which are of configurations adapted to withdraw from mutual engagement upon the torque exceeding a predetermined limit. The novel, advantageous features of the invention include the configuration of the mating, crown gear sets and the axially translatable, slidable drive gear. The mechanism is capable of transmitting a high degree of torque within a narrow, compact transmission housing. The compact size and narrow, elongated configuration of the housing is particularly applicable for use in hand tools and in multiple torque driver mechanisms in which it is necessary to drive multiple fasteners which are located in close proximity. Prior

  4. New Siemens applications for designing bevel gears

    Science.gov (United States)

    Goanta, A. M.; Dumitrache, P.

    2017-08-01

    The current situation in the design of gearings is different from software to software and in some cases requires specialized settings with or without additional costs. There are two ways of generating evolving tooting: one is based on the designer’s solid knowledge of geometry and gearing and the other is based on a series of automation subprograms for 3D modelling of gears. The first method is a general one, applicable to all design software that is based on generating a curve evolving specific to a tooth flank, continued with the construction of the symmetrical flank, the pattern multiplication of circular type around the center of the gear and finally generation of the three-dimensional characteristic of each individual tooth. The second method is much faster and requires only general knowledge about the gear but sufficiently advanced to allow permanent dialogue with the subprogram for generating cone gears. Absolute novelty items are brought about by the new NX design applications that lead to getting gears with curved teeth. In conclusion the paper shows how different variants of bevel gears are generated using various subprograms or performance settings, installed over the SIEMENS NX. An essential component of the paper is highlighting generation capacity of gears and gearing intended for predefined types of gear cutting machines such as those for Gleason and Oerlikon teeth.

  5. Hybrid foundry patterns of bevel gears

    Directory of Open Access Journals (Sweden)

    Budzik G.

    2007-01-01

    Full Text Available Possibilities of making hybrid foundry patterns of bevel gears for investment casting process are presented. Rapid prototyping of gears with complex tooth forms is possible with the use of modern methods. One of such methods is the stereo-lithography, where a pattern is obtained as a result of resin curing with laser beam. Patterns of that type are applicable in precision casting. Removing of stereo-lithographic pattern from foundry mould requires use of high temperatures. Resin burning would generate significant amounts of harmful gases. In case of a solid stereo-lithographic pattern, the pressure created during gas burning may cause the mould to crack. A gas volume reduction may be achieved by using patterns of honeycomb structure. However, this technique causes a significant worsening of accuracy of stereo-lithographic patterns in respect of their dimensions and shape. In cooperation with WSK PZL Rzeszów, the Machine Design Department of Rzeszow University of Technology carried out research on the design of hybrid stereo-lithographic patterns. Hybrid pattern consists of a section made by stereo-lithographic process and a section made of casting wax. The latter material is used for stereo-lithographic pattern filling and for mould gating system. The hybrid pattern process consists of two stages: wax melting and then the burn-out of stereolithographic pattern. Use of hybrid patterns reduces the costs of production of stereolithographic patterns. High dimensional accuracy remains preserved in this process.

  6. Distribution of Microstructure and Vickers Hardness in Spur Bevel Gear Formed by Cold Rotary Forging

    Directory of Open Access Journals (Sweden)

    Wuhao Zhuang

    2014-11-01

    Full Text Available Cold rotary forging is a novel metal forming technology which is widely used to produce the high performance gears. Investigating the microstructure and mechanical property of cold rotary forged gears has a great significance in improving their service performance. In this study, the grain morphology in different regions of the spur bevel gear which is processed by cold rotary forging is presented. And the distribution regulars of the grain deformation and Vickers hardness in the transverse and axial sections of the gear tooth are studied experimentally. A three-dimensional rigid-plastic FE model is developed to simulate the cold rotary forging process of a spur bevel gear under the DEFORM-3D software environment. The variation of effective strain in the spur bevel gear has been investigated so as to explain the distribution regulars of the microstructure and Vickers hardness. The results of this research thoroughly reveal the inhomogeneous deformation mechanisms in cold rotary forging of spur bevel gears and provide valuable guidelines for improving the performance of cold rotary forged spur bevel gears.

  7. Reingeniería de la geometría desconocida de engranajes cónicos con dientes rectos y curvilíneos. // Determination of the unknown geometry of straight and spiral bevel gears by means of inverse engineering.

    Directory of Open Access Journals (Sweden)

    G. González Rey

    2008-09-01

    Full Text Available En el trabajo se presenta un procedimiento para dar solución al problema de solución inversa asociado con la determinaciónde la geometría desconocida del dentado de un engranaje cónico con ejes ortogonales y dientes de altura proporcional enbase a cálculos de ingeniería de engranajes y con empleo de mediciones con herramientas de taller. El procedimientopropone un método práctico, con asistencia de un cálculo organizado linealmente y una búsqueda exhaustiva, para obtenerlos parámetros fundamentales del engranaje que puedan ser utilizados para el cálculo de la capacidad de carga deengranajes cónicos o cuando son “copiados” para realizar la generación de un nuevo engranaje según Normas ISO. Elprocedimiento de reingeniería, basado en la experiencia de los autores, establece su fundamento en minimizar la diferenciaentre parámetros geométricos medidos y calculados, como son los diámetros de crestas de las ruedas, alturas y espesores delos dientes. Los mencionados parámetros pueden ser calculados con una conveniente organización y evaluación de unsistema de fórmulas que involucran las relaciones entre las variables dependientes y variables independientes que se buscanen el proceso de solución al problema inverso de la geometría desconocida, como pueden ser el módulo, los parámetros dela herramienta de generación, los coeficientes de corrección radial y tangencial y el ángulo de la hélice de los dientes.Palabras claves: Engranaje cónico, ingeniería inversa, geometría de engranaje.______________________________________________________________________________AbstractA procedure for the solution of inverse problem to assist gear engineering designers in the cases of the determination ofthe basic unknown geometry of bevel gear with shaft angle of 90 degrees and standard depthwise tooth taper has beenpresented. The proposed method can be used as an alternative procedure to determine the unknown bevel gear geometryusing

  8. Hydrostatic self-locking bevel differential gear; Hydrostatisch selbstsperrendes Kegelraddifferentialgetriebe

    Energy Technology Data Exchange (ETDEWEB)

    Kalmbach, K.

    2001-07-01

    The product range of the rail vehicle industry comprises the construction of railroad material for long-distance and short-distance transport. This includes, for example, locomotives and cars, subway, light railway and tramway cars as well as rail vehicle equipment. The development of the industry is determined by the demand for transport services and government actions for the extension of railways and procurement of suitable vehicle types. In contrast to road vehicles, differential gears are only used in a negligible percentage of rail vehicles. Primarily in the short-distance rail transport sector, the demand for differential gears is growing due to increased drive power, smaller wheel diameters, lower vehicle mass with higher load capacity, the introduction of low-floor technology as well as the requirement of employing ever more quiet vehicles. In hydrostatic self-locking differential gears, oil is supplied to the gears within the differential gearbox. They only rotate relative to each other when the differential gear performs a compensation movement. In this case, oil is transported in the tooth space to the meshing of the gears, where it is displaced due to the meshing and must drain through tight gaps. The pressure generated by this process acts against the compensation movement of the gear, and the drive torque is transmitted to the wheel that has the higher friction. The achievable locking torque is linearly dependent on the differential speed of the drive wheel. This locking effect is achieved without wear-prone components and works automatically without active external intervention. The design space required corresponds to that of conventional differential gears, as the locking effect is integrated in the existing design. (orig.)

  9. Wear Characterization of Carbon Nanotubes Reinforced Acetal Spur, Helical, Bevel and Worm Gears Using a TS Universal Test Rig

    Science.gov (United States)

    Yousef, Samy; Osman, T. A.; Abdalla, Abdelrahman H.; Zohdy, Gamal A.

    2015-12-01

    Although the applications of nanotechnologies are increasing, there remains a significant barrier between nanotechnology and machine element applications. This work aims to remove this barrier by blending carbon nanotubes (CNT) with common types of acetal polymer gears (spur, helical, bevel and worm). This was done by using adhesive oil (paraffin) during injection molding to synthesize a flange and short bars containing 0.02% CNT by weight. The flanges and short bars were machined using hobbing and milling machines to produce nanocomposite polymer gears. Some defects that surfaced in previous work, such as the appearance of bubbles and unmelted pellets during the injection process, were avoided to produce an excellent dispersion of CNT in the acetal. The wear resistances of the gears were measured by using a TS universal test rig using constant parameters for all of the gears that were fabricated. The tests were run at a speed of 1420 rpm and a torque of 4 Nm. The results showed that the wear resistances of the CNT/acetal gears were increased due to the addition of CNT, especially the helical, bevel and worm gears.

  10. A New Design of the Universal Test Rig to Measure the Wear Characterizations of Polymer Acetal Gears (Spur, Helical, Bevel, and Worm

    Directory of Open Access Journals (Sweden)

    Samy Yousef

    2015-01-01

    Full Text Available This work aims to study the wear characterization of common types of acetal polymer gears (spur, helical, bevel, and worm using a new TS universal test rig, in order to obtain reliable results and as a reference when compared with acetal nanocomposite gears later. The TS universal test rig consists of three different units that are connected by a main driver shaft and a pair of constantly meshing metal spur gears, which transfer power to the bevel and worm test units. The first unit is used to test the bevel gears, the second unit is used to test the spur and helical gears, and the third unit is used to test the worm gears. The loading mechanism is similarly designed to block the brake mechanism. Hobbing and milling machines were used to machine an injection-moulded polymer flanges and produce the tested gears. All gear pairs, except the worm gear, have identical gear ratios. The experiments were performed at speed 1420 rpm and the torque was 4 Nm. The results showed that the wear rates (in the form of weight loss of spur gears were consistent with the previous results and the other gear types had larger wear rates.

  11. Importance of material and friction characterisation for FE-aided process design of hybrid bevel gears

    Science.gov (United States)

    Behrens, B.-A.; Bouguecha, A.; Bonk, C.; Matthias, T.

    2017-10-01

    Solid-forming components are often used in areas where they are subjected to very high loads. For most solid components locally divergent and sometimes contradictory requirements exist. Despite these contradictory requirements, almost exclusively monomaterials are nowadays used for the production of solid components. These components often reach their material-specific limits because of increasing demands on the products. Thus a significant increase in product quality and profitability would result from combining different materials in order to create tailored properties. In the Collaborative Research Center (CRC) 1153 "Tailored Forming" at the Leibniz Universität Hannover, this topic is investigated. The primary objective of the CRC 1153 is to develop and investigate new tailored manufacturing processes to produce reliable hybrid solid semi-finished components. In contrast to existing production processes of hybrid solid components, semi-finished workpieces in the CRC 1153 are joined before the forming phase. Thus, it will be possible to produce complex and highly stressable solid components made of different metals, which cannot be produced yet with the current used technologies. In this work the material and friction characteristics are investigated and the forming tool for the production of hybrid bevel gears made of different steel alloys (C22 and 41Cr4) is designed by numerical simulations. For this purpose, flow curves of both materials are determined by means of upsetting tests at process-related forming temperatures and strain rates. The temperature range for the forming process of the semi-finished product is determined by comparing the respective flow curves regarding similar flow stresses. Furthermore, the friction between the tool and the joining materials is investigated by means of ring upsetting tests at a process-relevant temperature. Finally, a stress analysis of the forming tools is carried out.

  12. Distortion control in 20MnCr5 bevel gears after liquid nitriding process to maintain precision dimensions

    Science.gov (United States)

    Mahendiran, M.; Kavitha, M.

    2018-02-01

    Robotic and automotive gears are generally very high precision components with limitations in tolerances. Bevel gears are more widely used and dimensionally very close tolerance components that need stability without any backlash or distortion for smooth and trouble free functions. Nitriding is carried out to enhance wear resistance of the surface. The aim of this paper is to reduce the distortion in liquid nitriding process, though plasma nitriding is preferred for high precision components. Various trials were conducted to optimize the process parameters, considering pre dimensional setting for nominal nitriding layer growth. Surface cleaning, suitable fixtures and stress relieving operations were also done to optimize the process. Micro structural analysis and Vickers hardness testing were carried out for analyzing the phase changes, variation in surface hardness and case depth. CNC gear testing machine was used for determining the distortion level. The presence of white layer was found for about 10-15μm in the case depth of 250± 3.5μm showing an average surface hardness of 670 HV. Hence the economical liquid nitriding process was successfully used for producing high hardness and wear resistant coating over 20MnCr5 material with less distortion and reduced secondary grinding process for dimensional control.

  13. The Influence of Changes in the Geometry of the Tooth Surface of the Pinion Bevel Gear on the Kinematic Accuracy of Pair Mesh

    Directory of Open Access Journals (Sweden)

    Płocica Mieczysław

    2014-08-01

    Full Text Available The paper describes the possibilities of bevel gears kinematics design on the basis of the motion graph and improving modifications to cut the pinion teeth flanks. The result is the ability to increase the accuracy of the kinematic transmission. The issue of changing the geometry of the pinion gear is considered in respect of a gear intended for the use in aviation, which requires the cooperation of high quality meshing. The basic geometric features that have been modified include the profile angle, the angle of tooth line, crowning trans-verse and longitudinal and lateral surface twist angle of the tooth. The modification of each of the selected geometrical parameters has had a different effect on the chart of transmission. It has been shown that the effect of the intended changes in the geometry of the pinion may reduce the deviation of motion delays gear and an improve the gear transmission chart.

  14. Computerized Design and Generation of Gear Drives With a Localized Bearing Contact and a Low Level of Transmission Errors

    Science.gov (United States)

    Litvin, F.; Chen, J.; Seol, I.; Kim, D.; Lu, J.; Zhao, X.; Handschuh, R.

    1996-01-01

    A general approach developed for the computerized simulation of loaded gear drives is presented. In this paper the methodology used to localize the bearing contact, provide a parabolic function of transmission errors, and simulate meshing and contact of unloaded gear drives is developed. The approach developed is applied to spur and helical gears, spiral bevel gears, face-gear drives, and worm-gear drives with cylindrical worms.

  15. Investigation of Sideband Index Response to Prototype Gear Tooth Damage

    Science.gov (United States)

    Dempsey, Paula J.

    2013-01-01

    The objective of this analysis was to evaluate the ability of gear condition indicators (CI) to detect contact fatigue damage on spiral bevel gear teeth. Tests were performed in the NASA Glenn Spiral Bevel Gear Fatigue Rig on eight prototype gear sets (pinion/gear). Damage was initiated and progressed on the gear and pinion teeth. Vibration data was measured during damage progression at varying torque values while varying damage modes to the gear teeth were observed and documented with inspection photos. Sideband indexes (SI) and root mean square (RMS) CIs were calculated from the time synchronous averaged vibration data. Results found that both CIs respond differently to varying torque levels, damage levels and damage modes

  16. Fabricación del dentado de engranajes cónicos helicoidales en fresadoras universales. // Helical bevel gears manufacturing in universal milling machines.

    Directory of Open Access Journals (Sweden)

    R. Hernández Riverón

    2004-01-01

    Full Text Available Este trabajo desarrolla el procedimiento para el cálculo de fabricación (fresado de engranajes cónicos helicoidales contecnología universal, obteniéndose de forma muy económica, significativamente rápida y con calidad satisfactoria, que lespermite operar por años en equipos que trabajan en régimen de explotación bastante intenso, como cabezales de fresadoras,cabezales de engrane para bombas de pozo profundo, etc.Palabras claves: Engranajes cónicos helicoidales, fresadoras helicoidales, tecnología universal.____________________________________________________________________________AbstractThis paper develops the method for manufacturing calculations (milling of helical bevel gears by means of universaltechnology, getting this in an economical way, fast and with satisfactory quality, which ensures to operate for years in hardworking conditions, such as milling machine heads, deep well pump heads etc.Key words: Helical bevel gears, universal milling machines, universal technology.

  17. Gears and gear drives

    CERN Document Server

    Jelaska, Damir T

    2012-01-01

    Understanding how gears are formed and how they interact or 'mesh' with each other is essential when designing equipment that uses gears or gear trains. The way in which gear teeth are formed and how they mesh is determined by their geometry and kinematics, which is the topic of this book.  Gears and Gear Drives provides the reader with comprehensive coverage of gears and gear drives. Spur, helical, bevel, worm and planetary gears are all covered, with consideration given to their classification, geometry, kinematics, accuracy control, load capacity and manufacturing. Cylindric

  18. Face Gear Technology for Aerospace Power Transmission Progresses

    Science.gov (United States)

    2005-01-01

    The use of face gears in an advanced rotorcraft transmission design was first proposed by the McDonnell Douglas Helicopter Company during their contracted effort with the U.S. Army under the Advanced Rotorcraft Transmission (ART) program. Face gears would be used to turn the corner between the horizontal gas turbine engine and the vertical output rotor shaft--a function currently done by spiral bevel gears. This novel gearing arrangement would substantially lower the drive system weight partly because a face gear mesh would be used to split the input power between two output gears. However, the use of face gears and their ability to operate successfully at the speeds and loads required for an aerospace environment was unknown. Therefore a proof-of-concept phase with an existing test stand at the NASA Lewis Research Center was pursued. Hardware was designed that could be tested in Lewis' Spiral Bevel Gear Test Rig. The initial testing indicated that the face gear mesh was a feasible design that could be used at high speeds and load. Surface pitting fatigue was the typical failure mode, and that could lead to tooth fracture. An interim project was conducted to see if slight modifications to the gear tooth geometry or an alternative heat treating process could overcome the surface fatigue problems. From the initial and interim tests, it was apparent that for the surface fatigue problems to be overcome the manufacturing process used for this component would have to be developed to the level used for spiral bevel gears. The current state of the art for face gear manufacturing required using less than optimal gear materials and manufacturing techniques because the surface of the tooth form does not receive final finishing after heat treatment as it does for spiral bevel gears. This resulted in less than desirable surface hardness and manufacturing tolerances. An Advanced Research and Projects Agency (ARPA) Technology Reinvestment Project has been funded to investigate

  19. On the automatic generation of FEM models for complex gears - A work-in-progress report

    Science.gov (United States)

    Drago, R. J.

    1982-01-01

    A description is presented of the development and use of a preprocessor to create a NASTRAN finite element model of a complex spur, helical, or spiral bevel gear quickly, inexpensively, and accurately. The preprocessor creates a ready to run NASTRAN input deck including the executive, case control, and bulk data sections. It generates nodes and solid elements to model spur, helical, or spiral bevel gear teeth with integral shafting. Either a complete gear shafting model or a symmetric model is created. The fundamental building block of the gear model is the base layer. The base layer is the mesh configuration of one layer of one tooth segment which is in turn duplicated, translated, and rotated to create the completed model of the gear. Once the base layer is created, the construction of the finite element model is straightforward.

  20. Vibration Based Sun Gear Damage Detection

    Science.gov (United States)

    Hood, Adrian; LaBerge, Kelsen; Lewicki, David; Pines, Darryll

    2013-01-01

    Seeded fault experiments were conducted on the planetary stage of an OH-58C helicopter transmission. Two vibration based methods are discussed that isolate the dynamics of the sun gear from that of the planet gears, bearings, input spiral bevel stage, and other components in and around the gearbox. Three damaged sun gears: two spalled and one cracked, serve as the focus of this current work. A non-sequential vibration separation algorithm was developed and the resulting signals analyzed. The second method uses only the time synchronously averaged data but takes advantage of the signal/source mapping required for vibration separation. Both algorithms were successful in identifying the spall damage. Sun gear damage was confirmed by the presence of sun mesh groups. The sun tooth crack condition was inconclusive.

  1. Gear Tooth Wear Detection Algorithm

    Science.gov (United States)

    Delgado, Irebert R.

    2015-01-01

    Vibration-based condition indicators continue to be developed for Health Usage Monitoring of rotorcraft gearboxes. Testing performed at NASA Glenn Research Center have shown correlations between specific condition indicators and specific types of gear wear. To speed up the detection and analysis of gear teeth, an image detection program based on the Viola-Jones algorithm was trained to automatically detect spiral bevel gear wear pitting. The detector was tested using a training set of gear wear pictures and a blind set of gear wear pictures. The detector accuracy for the training set was 75 percent while the accuracy for the blind set was 15 percent. Further improvements on the accuracy of the detector are required but preliminary results have shown its ability to automatically detect gear tooth wear. The trained detector would be used to quickly evaluate a set of gear or pinion pictures for pits, spalls, or abrasive wear. The results could then be used to correlate with vibration or oil debris data. In general, the program could be retrained to detect features of interest from pictures of a component taken over a period of time.

  2. Bifurcation Observation of Combining Spiral Gear Transmission Based on Parameter Domain Structure Analysis

    Directory of Open Access Journals (Sweden)

    He Lin

    2016-01-01

    Full Text Available This study considers the bifurcation evolutions for a combining spiral gear transmission through parameter domain structure analysis. The system nonlinear vibration equations are created with piecewise backlash and general errors. Gill’s numerical integration algorithm is implemented in calculating the vibration equation sets. Based on cell-mapping method (CMM, two-dimensional dynamic domain planes have been developed and primarily focused on the parameters of backlash, transmission error, mesh frequency and damping ratio, and so forth. Solution demonstrates that Period-doubling bifurcation happens as the mesh frequency increases; moreover nonlinear discontinuous jump breaks the periodic orbit and also turns the periodic state into chaos suddenly. In transmission error planes, three cell groups which are Period-1, Period-4, and Chaos have been observed, and the boundary cells are the sensitive areas to dynamic response. Considering the parameter planes which consist of damping ratio associated with backlash, transmission error, mesh stiffness, and external load, the solution domain structure reveals that the system step into chaos undergoes Period-doubling cascade with Period-2m (m: integer periodic regions. Direct simulations to obtain the bifurcation diagram and largest Lyapunov exponent (LE match satisfactorily with the parameter domain solutions.

  3. Gearing.

    Science.gov (United States)

    1985-12-01

    trichloroethyl phosphite and a phosphate ester containing a pentachlorphenyl radical. Most of the Asperity heights phosphorous compounds in gear oils...108) found that phosphorous compounds chemisorption. These boundary films can be thinner than ( 1 0 u ts n 0.025 pm (I in ) or several microinches thick...Pinion 1 .. dibutylxanthic acid disulfide. Ŗ %- Lead soaps have been used in lubricants for many 02 years. They resist the wiping and sliding action in

  4. An enhancement to the NA4 gear vibration diagnostic parameter

    Science.gov (United States)

    Decker, Harry J.; Handschuh, Robert F.; Zakrajsek, James J.

    1994-01-01

    A new vibration diagnostic parameter for health monitoring of gears, NA4*, is proposed and tested. A recently developed gear vibration diagnostic parameter NA4 outperformed other fault detection methods at indicating the start and initial progression of damage. However, in some cases, as the damage progressed, the sensitivity of the NA4 and FM4 parameters tended to decrease and no longer indicated damage. A new parameter, NA4* was developed by enhancing NA4 to improve the trending of the parameter. This allows for the indication of damage both at initiation and also as the damage progresses. The NA4* parameter was verified and compared to the NA4 and FM4 parameters using experimental data from single mesh spur and spiral bevel gear fatigue rigs. The primary failure mode for the test cases was naturally occurring tooth surface pitting. The NA4* parameter is shown to be a more robust indicator of damage.

  5. On the Boundary between Nonlinear Jump Phenomenon and Linear Response of Hypoid Gear Dynamics

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2011-01-01

    Full Text Available A nonlinear time-varying (NLTV dynamic model of a hypoid gear pair system with time-dependent mesh point, line-of-action vector, mesh stiffness, mesh damping, and backlash nonlinearity is formulated to analyze the transitional phase between nonlinear jump phenomenon and linear response. It is found that the classical jump discontinuity will occur if the dynamic mesh force exceeds the mean value of tooth mesh force. On the other hand, the propensity for the gear response to jump disappears when the dynamic mesh force is lower than the mean mesh force. Furthermore, the dynamic analysis is able to distinguish the specific tooth impact types from analyzing the behaviors of the dynamic mesh force. The proposed theory is general and also applicable to high-speed spur, helical and spiral bevel gears even though those types of gears are not the primary focus of this paper.

  6. Establecimiento del cálculo del diámetro de cresta exterior de un engranaje cónico con técnicas de grafos. // Procedure for the calculation of outer tip diameter on straight bevel gear by means of graphs technique.

    Directory of Open Access Journals (Sweden)

    G. González Rey

    2007-09-01

    Full Text Available Mediante un modelo matemático son dadas las principales relaciones entre los parámetros geométricos básicos requeridosen la evaluación del diámetro de cresta exterior de un engranaje ortogonal de ruedas cónicas con dientes rectos y suma decorrecciones radiales iguales a cero. Adicionalmente, serán brindados algunos resultados que asocian la correspondenciaentre una geometría racional y la capacidad de carga de un engranaje cónico con restricciones del diámetro de crestaexterior. Para la determinación de los procedimientos de cálculo, los problemas planteados sobre los modelos matemáticoshan sido serán representados por medio de grafos bicromáticos.Palabras claves: Engranajes cónicos, diseño racional, modelo matemático._______________________________________________________________________________Abstract:By means of a mathematical model, the main relations for the evaluation of the outer tip diameter on straight bevelgear with sum of the profile shift coefficients equal to zero are given. Additionally, some results associated with arational geometry and high load capacities of straight bevel gear with restrictions in the outer tip diameter arepresented. For the determination of the calculation procedures based on mathematical models was used thetechnique of representation by means of graphs.Key words: Straight bevel gear, rational design, mathematical models, graphs technique.

  7. Computer simulation of gear tooth manufacturing processes

    Science.gov (United States)

    Mavriplis, Dimitri; Huston, Ronald L.

    1990-01-01

    The use of computer graphics to simulate gear tooth manufacturing procedures is discussed. An analytical basis for the simulation is established for spur gears. The simulation itself, however, is developed not only for spur gears, but for straight bevel gears as well. The applications of the developed procedure extend from the development of finite element models of heretofore intractable geometrical forms, to exploring the fabrication of nonstandard tooth forms.

  8. Evaluation of MEMS-Based Wireless Accelerometer Sensors in Detecting Gear Tooth Faults in Helicopter Transmissions

    Science.gov (United States)

    Lewicki, David George; Lambert, Nicholas A.; Wagoner, Robert S.

    2015-01-01

    The diagnostics capability of micro-electro-mechanical systems (MEMS) based rotating accelerometer sensors in detecting gear tooth crack failures in helicopter main-rotor transmissions was evaluated. MEMS sensors were installed on a pre-notched OH-58C spiral-bevel pinion gear. Endurance tests were performed and the gear was run to tooth fracture failure. Results from the MEMS sensor were compared to conventional accelerometers mounted on the transmission housing. Most of the four stationary accelerometers mounted on the gear box housing and most of the CI's used gave indications of failure at the end of the test. The MEMS system performed well and lasted the entire test. All MEMS accelerometers gave an indication of failure at the end of the test. The MEMS systems performed as well, if not better, than the stationary accelerometers mounted on the gear box housing with regards to gear tooth fault detection. For both the MEMS sensors and stationary sensors, the fault detection time was not much sooner than the actual tooth fracture time. The MEMS sensor spectrum data showed large first order shaft frequency sidebands due to the measurement rotating frame of reference. The method of constructing a pseudo tach signal from periodic characteristics of the vibration data was successful in deriving a TSA signal without an actual tach and proved as an effective way to improve fault detection for the MEMS.

  9. Quantification of Gear Tooth Damage by Optimal Tracking of Vibration Signatures

    Science.gov (United States)

    Choy, F. K.; Veillette, R. J.; Polyshchuk, V.; Braun, M. J.; Hendricks, R. C.

    1996-01-01

    This paper presents a technique for quantifying the wear or damage of gear teeth in a transmission system. The procedure developed in this study can be applied as a part of either an onboard machine health-monitoring system or a health diagnostic system used during regular maintenance. As the developed methodology is based on analysis of gearbox vibration under normal operating conditions, no shutdown or special modification of operating parameters is required during the diagnostic process. The process of quantifying the wear or damage of gear teeth requires a set of measured vibration data and a model of the gear mesh dynamics. An optimization problem is formulated to determine the profile of a time-varying mesh stiffness parameter for which the model output approximates the measured data. The resulting stiffness profile is then related to the level of gear tooth wear or damage. The procedure was applied to a data set generated artificially and to another obtained experimentally from a spiral bevel gear test rig. The results demonstrate the utility of the procedure as part of an overall health-monitoring system.

  10. Bevel Gearbox Fault Diagnosis using Vibration Measurements

    Directory of Open Access Journals (Sweden)

    Hartono Dennis

    2016-01-01

    Full Text Available The use of vibration measurementanalysis has been proven to be effective for gearbox fault diagnosis. However, the complexity of vibration signals observed from a gearbox makes it difficult to accurately detectfaults in the gearbox. This work is based on a comparative studyof several time-frequency signal processing methods that can be used to extract information from transient vibration signals containing useful diagnostic information. Experiments were performed on a bevel gearbox test rig using vibration measurements obtained from accelerometers. Initially, thediscrete wavelet transform was implementedfor vibration signal analysis to extract the frequency content of signal from the relevant frequency region. Several time-frequency signal processing methods werethen incorporated to extract the fault features of vibration signals and their diagnostic performances were compared. It was shown thatthe Short Time Fourier Transform (STFT could not offer a good time resolution to detect the periodicity of the faulty gear tooth due the difficulty in choosing an appropriate window length to capture the impulse signal. The Continuous Wavelet Transform (CWT, on the other hand, was suitable to detection of vibration transients generated by localized fault from a gearbox due to its multi-scale property. However, both methods still require a thorough visual inspection. In contrast, it was shown from the experiments that the diagnostic method using the Cepstrumanalysis could provide a direct indication of the faulty tooth without the need of a thorough visual inspection as required by CWT and STFT.

  11. Hybrid Gear

    Science.gov (United States)

    Handschuh, Robert F. (Inventor); Roberts, Gary D. (Inventor)

    2016-01-01

    A hybrid gear consisting of metallic outer rim with gear teeth and metallic hub in combination with a composite lay up between the shaft interface (hub) and gear tooth rim is described. The composite lay-up lightens the gear member while having similar torque carrying capability and it attenuates the impact loading driven noise/vibration that is typical in gear systems. The gear has the same operational capability with respect to shaft speed, torque, and temperature as an all-metallic gear as used in aerospace gear design.

  12. Validation of Helicopter Gear Condition Indicators Using Seeded Fault Tests

    Science.gov (United States)

    Dempsey, Paula; Brandon, E. Bruce

    2013-01-01

    A "seeded fault test" in support of a rotorcraft condition based maintenance program (CBM), is an experiment in which a component is tested with a known fault while health monitoring data is collected. These tests are performed at operating conditions comparable to operating conditions the component would be exposed to while installed on the aircraft. Performance of seeded fault tests is one method used to provide evidence that a Health Usage Monitoring System (HUMS) can replace current maintenance practices required for aircraft airworthiness. Actual in-service experience of the HUMS detecting a component fault is another validation method. This paper will discuss a hybrid validation approach that combines in service-data with seeded fault tests. For this approach, existing in-service HUMS flight data from a naturally occurring component fault will be used to define a component seeded fault test. An example, using spiral bevel gears as the targeted component, will be presented. Since the U.S. Army has begun to develop standards for using seeded fault tests for HUMS validation, the hybrid approach will be mapped to the steps defined within their Aeronautical Design Standard Handbook for CBM. This paper will step through their defined processes, and identify additional steps that may be required when using component test rig fault tests to demonstrate helicopter CI performance. The discussion within this paper will provide the reader with a better appreciation for the challenges faced when defining a seeded fault test for HUMS validation.

  13. Logarithmic Spiral

    Indian Academy of Sciences (India)

    Switzerland) even today can see the. Archimedian spiral and the inscription under it on the tombstone of Jacob Bernoulli 1. Logarithmic Spiral in Nature. Apart from logarithmic spiral no other curve seems to have attracted the attention of scientists, ...

  14. Spiral symmetry

    CERN Document Server

    Hargittai, Istvan

    1992-01-01

    From the tiny twisted biological molecules to the gargantuan curling arms of many galaxies, the physical world contains a startling repetition of spiral patterns. Today, researchers have a keen interest in identifying, measuring, and defining these patterns in scientific terms. Spirals play an important role in the growth processes of many biological forms and organisms. Also, through time, humans have imitated spiral motifs in their art forms, and invented new and unusual spirals which have no counterparts in the natural world. Therefore, one goal of this multiauthored book is to stress the c

  15. A study on the automated design system for gear

    Energy Technology Data Exchange (ETDEWEB)

    Cho, H. Y.; Nam, G. J.; Oh, B. K. [Chungbuk National Univ., Cheongju (Korea, Republic of)

    2001-07-01

    A computer aided design system for spur, helical, bevel and worm gears by using AutoCAD system and its AutoLISP computer language was newly developed in this study. Two methods are available for a designer to draw a gear. The first method needs the gear design parameters such as pressure, module, number of tooth, shaft angle, velocity, materials, etc. When the gear design parameters are inputted, a gear is drawn in AutoCAD system and maximum allowable power and shaft diameter are calculated additionally. The second method calculates all dimensions and gear design parameters to draw a gear when the information such as transmission, reduction ratio, rpm, materials and pressure are inputted. The system includes four programs. Each program is composed of a data input module, a database module, a strength calculation module, a drawing module, a text module and a drawing edit module. In conclusion, the CAD system would be widely used in companies to find the geometric data and manufacturing course.

  16. A study on the automated design system for gear

    International Nuclear Information System (INIS)

    Cho, H. Y.; Nam, G. J.; Oh, B. K.

    2001-01-01

    A computer aided design system for spur, helical, bevel and worm gears by using AutoCAD system and its AutoLISP computer language was newly developed in this study. Two methods are available for a designer to draw a gear. The first method needs the gear design parameters such as pressure, module, number of tooth, shaft angle, velocity, materials, etc. When the gear design parameters are inputted, a gear is drawn in AutoCAD system and maximum allowable power and shaft diameter are calculated additionally. The second method calculates all dimensions and gear design parameters to draw a gear when the information such as transmission, reduction ratio, rpm, materials and pressure are inputted. The system includes four programs. Each program is composed of a data input module, a database module, a strength calculation module, a drawing module, a text module and a drawing edit module. In conclusion, the CAD system would be widely used in companies to find the geometric data and manufacturing course

  17. On the aeroacoustic properties of a beveled plate

    NARCIS (Netherlands)

    Van der Velden, W.C.P.; Van Zuijlen, A.H.; De Jong, A.T.; Bijl, H.

    2015-01-01

    The flow around a beveled flat plate model with an asymmetric 25 degrees trailing edge with three rounding radii is analyzed using a Navier-Stokes based open source software package OpenFOAM in order to predict the aeroacoustic properties of the models. A Large Eddy Simulation with a dynamic

  18. Frequency spirals

    International Nuclear Information System (INIS)

    Ottino-Löffler, Bertrand; Strogatz, Steven H.

    2016-01-01

    We study the dynamics of coupled phase oscillators on a two-dimensional Kuramoto lattice with periodic boundary conditions. For coupling strengths just below the transition to global phase-locking, we find localized spatiotemporal patterns that we call “frequency spirals.” These patterns cannot be seen under time averaging; they become visible only when we examine the spatial variation of the oscillators' instantaneous frequencies, where they manifest themselves as two-armed rotating spirals. In the more familiar phase representation, they appear as wobbly periodic patterns surrounding a phase vortex. Unlike the stationary phase vortices seen in magnetic spin systems, or the rotating spiral waves seen in reaction-diffusion systems, frequency spirals librate: the phases of the oscillators surrounding the central vortex move forward and then backward, executing a periodic motion with zero winding number. We construct the simplest frequency spiral and characterize its properties using analytical and numerical methods. Simulations show that frequency spirals in large lattices behave much like this simple prototype.

  19. Frequency spirals

    Energy Technology Data Exchange (ETDEWEB)

    Ottino-Löffler, Bertrand; Strogatz, Steven H., E-mail: strogatz@cornell.edu [Center for Applied Mathematics, Cornell University, Ithaca, New York 14853 (United States)

    2016-09-15

    We study the dynamics of coupled phase oscillators on a two-dimensional Kuramoto lattice with periodic boundary conditions. For coupling strengths just below the transition to global phase-locking, we find localized spatiotemporal patterns that we call “frequency spirals.” These patterns cannot be seen under time averaging; they become visible only when we examine the spatial variation of the oscillators' instantaneous frequencies, where they manifest themselves as two-armed rotating spirals. In the more familiar phase representation, they appear as wobbly periodic patterns surrounding a phase vortex. Unlike the stationary phase vortices seen in magnetic spin systems, or the rotating spiral waves seen in reaction-diffusion systems, frequency spirals librate: the phases of the oscillators surrounding the central vortex move forward and then backward, executing a periodic motion with zero winding number. We construct the simplest frequency spiral and characterize its properties using analytical and numerical methods. Simulations show that frequency spirals in large lattices behave much like this simple prototype.

  20. Reingeniería de la geometría desconocida de engranajes cónicos con dientes rectos y curvilíneos. // Determination of the unknown geometry of straight and spiral bevel gears by means of inverse engineering.

    OpenAIRE

    G. González Rey; S. A. Marrero Osorio

    2008-01-01

    En el trabajo se presenta un procedimiento para dar solución al problema de solución inversa asociado con la determinaciónde la geometría desconocida del dentado de un engranaje cónico con ejes ortogonales y dientes de altura proporcional enbase a cálculos de ingeniería de engranajes y con empleo de mediciones con herramientas de taller. El procedimientopropone un método práctico, con asistencia de un cálculo organizado linealmente y una búsqueda exhaustiva, para obtenerlos parámetros fundame...

  1. Acoustic Emission Signatures of Fatigue Damage in Idealized Bevel Gear Spline for Localized Sensing

    Directory of Open Access Journals (Sweden)

    Lu Zhang

    2017-06-01

    Full Text Available In many rotating machinery applications, such as helicopters, the splines of an externally-splined steel shaft that emerges from the gearbox engage with the reverse geometry of an internally splined driven shaft for the delivery of power. The splined section of the shaft is a critical and non-redundant element which is prone to cracking due to complex loading conditions. Thus, early detection of flaws is required to prevent catastrophic failures. The acoustic emission (AE method is a direct way of detecting such active flaws, but its application to detect flaws in a splined shaft in a gearbox is difficult due to the interference of background noise and uncertainty about the effects of the wave propagation path on the received AE signature. Here, to model how AE may detect fault propagation in a hollow cylindrical splined shaft, the splined section is essentially unrolled into a metal plate of the same thickness as the cylinder wall. Spline ridges are cut into this plate, a through-notch is cut perpendicular to the spline to model fatigue crack initiation, and tensile cyclic loading is applied parallel to the spline to propagate the crack. In this paper, the new piezoelectric sensor array is introduced with the purpose of placing them within the gearbox to minimize the wave propagation path. The fatigue crack growth of a notched and flattened gearbox spline component is monitored using a new piezoelectric sensor array and conventional sensors in a laboratory environment with the purpose of developing source models and testing the new sensor performance. The AE data is continuously collected together with strain gauges strategically positioned on the structure. A significant amount of continuous emission due to the plastic deformation accompanied with the crack growth is observed. The frequency spectra of continuous emissions and burst emissions are compared to understand the differences of plastic deformation and sudden crack jump. The correlation of the cumulative AE events at the notch tip and the strain data is used to predict crack growth. The performance of the new sensor array is compared with the conventional AE sensors in terms of signal to noise ratio and the ability to detect fatigue cracking.

  2. Modern gear production

    CERN Document Server

    Watson, H J

    1970-01-01

    Modern Gear Production focuses on the processes and methods in gear making. The book first gives information on the history of gear making and types of gears. Topics such as the classification of gears based on the disposition of their shafts; shafts lying in the same plane with axes intersecting; and shafts lying in parallel planes but with axes inclined to one another are then discussed. The text describes gear groups, tooth forms, and gear materials. Heat treatment of steels, casehardening, nitriding, induction hardening, sulfinuzing, and flame hardening are explained. The book takes a look

  3. Kinematic geometry of gearing

    CERN Document Server

    Dooner, David B

    2012-01-01

    Building on the first edition published in 1995 this new edition of Kinematic Geometry of Gearing has been extensively revised and updated with new and original material. This includes the methodology for general tooth forms, radius of torsure', cylinder of osculation, and cylindroid of torsure; the author has also completely reworked the '3 laws of gearing', the first law re-written to better parallel the existing 'Law of Gearing" as pioneered by Leonard Euler, expanded from Euler's original law to encompass non-circular gears and hypoid gears, the 2nd law of gearing describing a unique relat

  4. 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.

  5. Offset Compound Gear Drive

    Science.gov (United States)

    Stevens, Mark A.; Handschuh, Robert F.; Lewicki, David G.

    2010-01-01

    The Offset Compound Gear Drive is an in-line, discrete, two-speed device utilizing a special offset compound gear that has both an internal tooth configuration on the input end and external tooth configuration on the output end, thus allowing it to mesh in series, simultaneously, with both a smaller external tooth input gear and a larger internal tooth output gear. This unique geometry and offset axis permits the compound gear to mesh with the smaller diameter input gear and the larger diameter output gear, both of which are on the same central, or primary, centerline. This configuration results in a compact in-line reduction gear set consisting of fewer gears and bearings than a conventional planetary gear train. Switching between the two output ratios is accomplished through a main control clutch and sprag. Power flow to the above is transmitted through concentric power paths. Low-speed operation is accomplished in two meshes. For the purpose of illustrating the low-speed output operation, the following example pitch diameters are given. A 5.0 pitch diameter (PD) input gear to 7.50 PD (internal tooth) intermediate gear (0.667 reduction mesh), and a 7.50 PD (external tooth) intermediate gear to a 10.00 PD output gear (0.750 reduction mesh). Note that it is not required that the intermediate gears on the offset axis be of the same diameter. For this example, the resultant low-speed ratio is 2:1 (output speed = 0.500; product of stage one 0.667 reduction and stage two 0.750 stage reduction). The design is not restricted to the example pitch diameters, or output ratio. From the output gear, power is transmitted through a hollow drive shaft, which, in turn, drives a sprag during which time the main clutch is disengaged.

  6. The spiral

    DEFF Research Database (Denmark)

    Bibace, Roger; Kharlamov, Nikita

    2013-01-01

    ’s work with Bernard Kaplan on symbol formation is a primer on this idea. This paper examines the idea of spirality and develops the notion of dynamic coexistence that can clarify the issue of directionality of development; that is, what is the general trajectory or ground plan that development assumes...... and the environment. The idea of dynamic coexistence is developed on this foundation. In the context of Werner and Kaplan’s work, dynamic coexistence represents the syncretic nature of processes and levels of organization: they are neither innately fused nor organized. Instead, the antithesis between fusion...

  7. On the aeroacoustic properties of a beveled plate

    Directory of Open Access Journals (Sweden)

    van der Velden W.C.P.

    2015-01-01

    Full Text Available The flow around a beveled flat plate model with an asymmetric 25 degrees trailing edge with three rounding radii is analyzed using a Navier-Stokes based open source software package OpenFOAM in order to predict the aeroacoustic properties of the models. A Large Eddy Simulation with a dynamic Smagorinsky and implicit model are used as closure model for the flow solver, and are compared regarding their aeroacoustic performance. Velocity coherence and pressure correlation is determined in spanwise direction. The acoustic far field spectrum is obtained by solving Curle’s analogy in frequency domain as a post-processing step.

  8. Parametric surface and properties defined on parallelogrammic domain

    OpenAIRE

    Shuqian Fan; Jinsong Zou; Mingquan Shi

    2014-01-01

    Similar to the essential components of many mechanical systems, the geometrical properties of the teeth of spiral bevel gears greatly influence the kinematic and dynamic behaviors of mechanical systems. Logarithmic spiral bevel gears show a unique advantage in transmission due to their constant spiral angle property. However, a mathematical model suitable for accurate digital modeling, differential geometrical characteristics, and related contact analysis methods for tooth surfaces have not b...

  9. Landing gear noise attenuation

    Science.gov (United States)

    Moe, Jeffrey W. (Inventor); Whitmire, Julia (Inventor); Kwan, Hwa-Wan (Inventor); Abeysinghe, Amal (Inventor)

    2011-01-01

    A landing gear noise attenuator mitigates noise generated by airframe deployable landing gear. The noise attenuator can have a first position when the landing gear is in its deployed or down position, and a second position when the landing gear is in its up or stowed position. The noise attenuator may be an inflatable fairing that does not compromise limited space constraints associated with landing gear retraction and stowage. A truck fairing mounted under a truck beam can have a compliant edge to allow for non-destructive impingement of a deflected fire during certain conditions.

  10. Estimating Gear Teeth Stiffness

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard

    2013-01-01

    The estimation of gear stiffness is important for determining the load distribution between the gear teeth when two sets of teeth are in contact. Two factors have a major influence on the stiffness; firstly the boundary condition through the gear rim size included in the stiffness calculation...... and secondly the size of the contact. In the FE calculation the true gear tooth root profile is applied. The meshing stiffness’s of gears are highly non-linear, it is however found that the stiffness of an individual tooth can be expressed in a linear form assuming that the contact length is constant....

  11. Spiral tectonics

    Science.gov (United States)

    Hassan Asadiyan, Mohammad

    2014-05-01

    Spiral Tectonics (ST) is a new window to global tectonics introduced as alternative model for Plate Tectonics (PT). ST based upon Dahw(rolling) and Tahw(spreading) dynamics. Analogues to electric and magnetic components in the electromagnetic theory we could consider Dahw and Tahw as components of geodynamics, when one component increases the other decreases and vice versa. They are changed to each other during geological history. D-component represents continental crust and T-component represents oceanic crust. D and T are two arm of spiral-cell. T-arm 180 degree lags behind D-arm so named Retard-arm with respect to D or Forward-arm. It seems primary cell injected several billions years ago from Earth's center therefore the Earth's core was built up first then mantel and finally the crust was build up. Crust building initiate from Arabia (Mecca). As the universe extended gravitation wave swirled the earth fractaly along cycloid path from big to small scale. In global scale (order-0) ST collect continents in one side and abandoned Pacific Ocean in the other side. Recent researches also show two mantels upwelling in opposite side of the Earth: one under Africa (tectonic pose) and the other under Pacific Ocean (tectonic tail). In higher order (order-1) ST build up Africa in one side and S.America in the other side therefore left Atlantic Ocean meandered in between. In order-n e.g. Khoor Musa and Bandar-Deylam bay are seen meandered easterly in the Iranian part but Khoor Abdullah and Kuwait bay meandered westerly in the Arabian part, they are distributed symmetrically with respect to axis of Persian Gulf(PG), these two are fractal components of easterly Caspian-wing and westerly Black Sea-wing which split up from Anatoly. Caspian Sea and Black Sea make two legs of Y-like structure, this shape completely fitted with GPS-velocity map which start from PG and split up in the Catastrophic Point(Anatoly). We could consider PG as remnants of Ancient Ocean which spent up

  12. 50 CFR 665.127 - Allowable gear and gear restrictions.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Allowable gear and gear restrictions. 665... Fisheries § 665.127 Allowable gear and gear restrictions. (a) American Samoa coral reef ecosystem MUS may be taken only with the following allowable gear and methods: (1) Hand harvest; (2) Spear; (3) Slurp gun; (4...

  13. 50 CFR 665.627 - Allowable gear and gear restrictions.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Allowable gear and gear restrictions. 665... Island Area Fisheries § 665.627 Allowable gear and gear restrictions. (a) Coral reef ecosystem MUS may be taken only with the following allowable gear and methods: (1) Hand harvest; (2) Spear; (3) Slurp gun; (4...

  14. 50 CFR 665.227 - Allowable gear and gear restrictions.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Allowable gear and gear restrictions. 665... Fisheries § 665.227 Allowable gear and gear restrictions. (a) Hawaii coral reef ecosystem MUS may be taken only with the following allowable gear and methods: (1) Hand harvest; (2) Spear; (3) Slurp gun; (4...

  15. 50 CFR 665.427 - Allowable gear and gear restrictions.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Allowable gear and gear restrictions. 665... Archipelago Fisheries § 665.427 Allowable gear and gear restrictions. (a) Mariana coral reef ecosystem MUS may be taken only with the following allowable gear and methods: (1) Hand harvest; (2) Spear; (3) Slurp...

  16. Gearing Up for Mountain Biking.

    Science.gov (United States)

    Jahnke, Thomas; Hamson, Mike

    1999-01-01

    Examines the gear system of a mountain bike to discover any redundancy in the many gear settings available to the cyclist. Suggests a best strategy for changing up through the gears on a typical 21-gear system and an adjustment to the available gears that would result in a smoother change. (Author/ASK)

  17. 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.

  18. Observations of barred spirals

    International Nuclear Information System (INIS)

    Elmegreen, D.M.

    1990-01-01

    Observations of barred spiral galaxies are discussed which show that the presence of a bar increases the likelihood for grand design spiral structure only in early Hubble types. This result is contrary to the more common notion that grand design spiral structure generally accompanies bars in galaxies. Enhanced deprojected color images are shown which reveal that a secondary set of spiral arms commonly occurs in barred galaxies and also occasionally in ovally distorted galaxies. 6 refs

  19. Communication: Molecular gears

    Energy Technology Data Exchange (ETDEWEB)

    Burnell, E. Elliott, E-mail: elliott.burnell@ubc.ca [Chemistry Department, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1 (Canada); Lange, Cornelis A. de, E-mail: c.a.de.lange@vu.nl [Atomic, Molecular and Laser Physics, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands); Meerts, W. Leo, E-mail: leo.meerts@science.ru.nl [Atomic, Molecular and Laser Physics, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands); Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, NL-6525 AJ Nijmegen (Netherlands)

    2016-09-07

    The {sup 1}H nuclear magnetic resonance spectrum of hexamethylbenzene orientationally ordered in the nematic liquid crystal ZLI-1132 is analysed using covariance matrix adaptation evolution strategy. The spectrum contains over 350 000 lines with many overlapping transitions, from which four independent direct dipolar couplings are obtained. The rotations of the six methyl groups appear to be correlated due to mutual steric hindrance. Adjacent methyl groups show counter-rotating or geared motion. Hexamethylbenzene thus behaves as a molecular hexagonal gear.

  20. The cycloid Permanent Magnetic Gear

    DEFF Research Database (Denmark)

    Rasmussen, Peter Omand; Andersen, Torben Ole; Jørgensen, Frank T.

    2008-01-01

    This paper presents a new permanent-magnet gear based on the cycloid gearing principle. which normally is characterized by an extreme torque density and a very high gearing ratio. An initial design of the proposed magnetic gear was designed, analyzed, and optimized with an analytical model...... regarding torque density. The results were promising as compared to other high-performance magnetic-gear designs. A test model was constructed to verify the analytical model....

  1. Electromechanics of graphene spirals

    Energy Technology Data Exchange (ETDEWEB)

    Korhonen, Topi; Koskinen, Pekka, E-mail: pekka.koskinen@iki.fi [NanoScience Center, Department of Physics, University of Jyväskylä, 40014 Jyväskylä (Finland)

    2014-12-15

    Among the most fascinating nanostructure morphologies are spirals, hybrids of somewhat obscure topology and dimensionality with technologically attractive properties. Here, we investigate mechanical and electromechanical properties of graphene spirals upon elongation by using density-functional tight-binding, continuum elasticity theory, and classical force field molecular dynamics. It turns out that electronic properties are governed by interlayer interactions as opposed to strain effects. The structural behavior is governed by van der Waals interaction: in its absence spirals unfold with equidistant layer spacings, ripple formation at spiral perimeter, and steadily increasing axial force; in its presence, on the contrary, spirals unfold via smooth local peeling, complex geometries, and nearly constant axial force. These electromechanical trends ought to provide useful guidelines not only for additional theoretical investigations but also for forthcoming experiments on graphene spirals.

  2. Do Superior or Inferior Interlaminar Approach or Bevel Orientation Predispose to Nonepidural Needle Penetration?

    Science.gov (United States)

    Koontz, Nicholas A; Wiggins, Richard H; Stoddard, Gregory J; Shah, Lubdha M

    2017-10-01

    There is a paucity of evidence-based literature regarding the advantages and disadvantages of the interlaminar approach and needle bevel orientation for performing a lumbar interlaminar epidural steroid injection (ESI). The purpose of this study was to determine if superior versus inferior lamina approach, needle bevel tip orientation, or both may predispose to inadvertent nonepidural penetration during lumbar interlaminar ESI. A prospective study was performed of patients with low back pain with or without radicular pain or neurogenic claudication referred for lumbar interlaminar ESI. Two hundred eleven patients were randomized by interlaminar approach (superior vs inferior) and bevel tip orientation (cranial vs caudal). Lumbar interlaminar ESI was performed by six interventionalists of varying levels of experience using fluoroscopic guidance with curved tip epidural needles, using loss-of-resistance technique and confirmation with contrast opacification. Exact Poisson regression was used to model the study outcome. Two hundred twenty-one lumbar interlaminar ESIs were performed on 211 patients, randomized to a superior (n = 121) or inferior lamina approach (n = 100) and to a cranial (n = 103) or caudal (n = 118) orientation of the bevel tip. Epidural needle placement was confirmed in 96.4% (n = 213) of cases. Nonepidural needle placement was most commonly associated with superior lamina approach and caudal bevel tip orientation, which was marginally significant (adjusted risk ratio, 6.88; 95% CI, 0.93-∞; p = 0.059). Inadvertent nonepidural needle penetration during fluoroscopically guided lumbar interlaminar ESI appears to be affected by approach, with superior lamina approach and caudal bevel tip orientation being the least favorable technique.

  3. A superconducting magnetic gear

    International Nuclear Information System (INIS)

    Campbell, A M

    2016-01-01

    A comparison is made between a magnetic gear using permanent magnets and superconductors. The objective is to see if there are any fundamental reasons why superconducting magnets should not provide higher power densities than permanent magnets. The gear is based on the variable permeability design of Attilah and Howe (2001 IEEE Trans. Magn. 37 2844–46) in which a ring of permanent magnets surrounding a ring of permeable pole pieces with a different spacing gives an internal field component at the beat frequency. Superconductors can provide much larger fields and forces but will saturate the pole pieces. However the gear mechanism still operates, but in a different way. The magnetisation of the pole pieces is now constant but rotates with angle at the beat frequency. The result is a cylindrical Halbach array which produces an internal field with the same symmetry as in the linear regime, but has an analytic solution. In this paper a typical gear system is analysed with finite elements using FlexPDE. It is shown that the gear can work well into the saturation regime and that the Halbach array gives a good approximation to the results. Replacing the permanent magnets with superconducting tapes can give large increases in torque density, and for something like a wind turbine a combined gear and generator is possible. However there are major practical problems. Perhaps the most fundamental is the large high frequency field which is inevitably present and which will cause AC losses. Also large magnetic fields are required, with all the practical problems of high field superconducting magnets in rotating machines. Nevertheless there are ways of mitigating these difficulties and it seems worthwhile to explore the possibilities of this technology further. (paper)

  4. Laser processing for bevel termination of high voltage pn junction in SiC

    International Nuclear Information System (INIS)

    Kubiak, A; Ruta, Ł; Rosowski, A; French, P

    2016-01-01

    Proper edge termination of the p-n junction in silicon carbide is a key requirement in the fabrication of discrete devices able to withstand high voltages in reverse polarization. Due to the hardness of SiC the creation of the bevel termination remains difficult using mechanical machining. The use of laser beam sources with medium wavelength (532 nm) gives new possibilities in the machining of the silicon carbide. The paper presents the fabrication of the bevel termination structure in SiC using a green DPSS laser equipped with scanner and dedicated rotating sample holder. Characterization of the resulting structures proves the high potential of the proposed approach. (paper)

  5. Vehicle transmission gear 2009; Getriebe in Fahrzeugen 2009

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-07-01

    : functionality, design and development methodology (A. Giacometti); (18) DCT system approach: Choose drive away and shift feeling (O. Einfinger); (19) An example for the use of adaptive methods in powertrain control of heavy duty vehicles (C. Joachim); (20) The effect of lubricating oils on bearing fatigue-life using the Evonik RohMax pitting test procedure (T. Bartels); (21) Influence of lubricant on the pitting capacity of gears - Comparison and discussion of main pitting test methods (B.-R. Hoehn); (22) Reduction of CO{sub 2} emission by means of innovative, tailor-made gear oils (P. Kraneburg); (23) Development of a force element for the emulation of the dynamic behaviour of bevel gears (C. Brecher); (24) A simulation software for the optimisation of the gearing of conical toothed gears (H. Alxneit); (25) Fatigue life optimization for hypoid gears (Ch. Haberer); (26) BorgWarner DualTronic {sup registered} transmission concepts for efficiency, cost and robustness (A. Moser); (27) Hy Tronic - The hybrid system for distributor commercial vehicles on the bases of a modular NKW gear family (S. Wallner); (28) New drive axles for hybrid applications in low-floor city busses (U. Solka); (29) Design, construction and integration of hybrid drive components in commercial vehicles (S. Kerschl); (30) Cold trip to chassis roller dyno (J. Lewis); (31) Model-based development of a dual-clutch transmission using rapid prototyping and SiL (H. Brueckmann); (31) New synchroniser system for modern transmissions (O. Back); (32) Improving shift dynamics and efficiency of MTs, AMTs and DCTs using full servo synchronizers (T. Hackl); (33) N{sup T} {sup registered} LightDiff: Innovative, lightweight concept for bevel-gear differentials (M. Derse); (34) Hybrid concepts of the co-operation GETRAG-BOSCH and their realisation in a demonstrator car (B. Blankenbach); (35) The conservation potential of consumption of the ZF hybrid gear system (R. Kubalczyk); (36) FEV's new parallel hybrid transmission

  6. On gear tooth stiffness evaluation

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard; Jørgensen, Martin Felix

    2014-01-01

    The estimation of gear stiffness is important for determining the load distribution between the gear teeth when two sets of teeth are in contact. Two factors have a major influence on the stiffness; firstly the boundary condition through the gear rim size included in the stiffness calculation...

  7. 49 CFR 230.89 - Reverse gear.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Reverse gear. 230.89 Section 230.89 Transportation... Reversing Gear § 230.89 Reverse gear. (a) General provisions. Reverse gear, reverse levers, and quadrants... quadrant. Proper counterbalance shall be provided for the valve gear. (b) Air-operated power reverse gear...

  8. analysis of gear milling at vari gear milling at various gear milling

    African Journals Online (AJOL)

    eobe

    2 DEPARTMENT OF INDUSTRIAL AND ... conventional machine tools, cutter tool wear, .... speed, and tool wear on case-hardened gear is also .... study. The gear cutter is mounted on the spindle. Spindle speeds and feed rates are essential ...

  9. Triangular spiral tilings

    International Nuclear Information System (INIS)

    Sushida, Takamichi; Hizume, Akio; Yamagishi, Yoshikazu

    2012-01-01

    The topology of spiral tilings is intimately related to phyllotaxis theory and continued fractions. A quadrilateral spiral tiling is determined by a suitable chosen triple (ζ, m, n), where ζ element of D/R, and m and n are relatively prime integers. We give a simple characterization when (ζ, m, n) produce a triangular spiral tiling. When m and n are fixed, the admissible generators ζ form a curve in the unit disk. The family of triangular spiral tilings with opposed parastichy pairs (m, n) is parameterized by the divergence angle arg (ζ), while triangular spiral tilings with non-opposed parastichy pairs are parameterized by the plastochrone ratio 1/|ζ|. The generators for triangular spiral tilings with opposed parastichy pairs are not dense in the complex parameter space, while those with non-opposed parastichy pairs are dense. The proofs will be given in a general setting of spiral multiple tilings. We present paper-folding (origami) sheets that build spiral towers whose top-down views are triangular tilings. (paper)

  10. Spiral Countercurrent Chromatography

    Science.gov (United States)

    Ito, Yoichiro; Knight, Martha; Finn, Thomas M.

    2013-01-01

    For many years, high-speed countercurrent chromatography conducted in open tubing coils has been widely used for the separation of natural and synthetic compounds. In this method, the retention of the stationary phase is solely provided by the Archimedean screw effect by rotating the coiled column in the centrifugal force field. However, the system fails to retain enough of the stationary phase for polar solvent systems such as the aqueous–aqueous polymer phase systems. To address this problem, the geometry of the coiled channel was modified to a spiral configuration so that the system could utilize the radially acting centrifugal force. This successfully improved the retention of the stationary phase. Two different types of spiral columns were fabricated: the spiral disk assembly, made by stacking multiple plastic disks with single or four interwoven spiral channels connected in series, and the spiral tube assembly, made by inserting the tetrafluoroethylene tubing into a spiral frame (spiral tube support). The capabilities of these column assemblies were successfully demonstrated by separations of peptides and proteins with polar two-phase solvent systems whose stationary phases had not been well retained in the earlier multilayer coil separation column for high-speed countercurrent chromatography. PMID:23833207

  11. Spirals on the sea

    Directory of Open Access Journals (Sweden)

    Walter Munk

    2001-12-01

    Full Text Available Spiral eddies were first seen in the sun glitter on the Apollo Mission 30 years ago; they have since been recorded on SAR missions and in the infrared. The spirals are globally distributed, 10-25 km in size and overwhelmingly cyclonic. They have not been explained. Under light winds favorable to visualization, linear surface features with high surfactant density and low surface roughness are of common occurrence. We have proposed that frontal formations concentrate the ambient shear and prevailing surfactants. Horizontal shear instabilities ensue when the shear becomes comparable to the coriolis frequency. The resulting vortices wind the liner features into spirals. The hypothesis needs to be tested by prolonged measurements and surface truth. Spiral eddies are a manifestation of a sub-mesoscale oceanography associated with upper ocean stirring; dimensional considerations suggest a horizontal diffusivity of order 103 m2 s-1.

  12. Spiral 2 Week

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    The main goal of this meeting is to present and discuss the current status of the Spiral-2 project at GANIL in front of a large community of scientists and engineers. Different issues have been tackled particularly the equipment around Spiral-2 like injectors, cryo-modules or beam diagnostics, a workshop was devoted to other facilities dedicated to radioactive ion beam production. This document gathers only the slides of the presentations.

  13. Stacking the Equiangular Spiral

    OpenAIRE

    Agrawal, A.; Azabi, Y. O.; Rahman, B. M.

    2013-01-01

    We present an algorithm that adapts the mature Stack and Draw (SaD) methodology for fabricating the exotic Equiangular Spiral Photonic Crystal Fiber. (ES-PCF) The principle of Steiner chains and circle packing is exploited to obtain a non-hexagonal design using a stacking procedure based on Hexagonal Close Packing. The optical properties of the proposed structure are promising for SuperContinuum Generation. This approach could make accessible not only the equiangular spiral but also other qua...

  14. Spiral 2 Week

    International Nuclear Information System (INIS)

    2007-01-01

    The main goal of this meeting is to present and discuss the current status of the Spiral-2 project at GANIL in front of a large community of scientists and engineers. Different issues have been tackled particularly the equipment around Spiral-2 like injectors, cryo-modules or beam diagnostics, a workshop was devoted to other facilities dedicated to radioactive ion beam production. This document gathers only the slides of the presentations

  15. High-Assurance Spiral

    Science.gov (United States)

    2017-11-01

    HIGH-ASSURANCE SPIRAL CARNEGIE MELLON UNIVERSITY NOVEMBER 2017 FINAL TECHNICAL REPORT APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED STINFO...MU 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Carnegie Mellon University 5000 Forbes Ave Pittsburgh, PA 15217 8. PERFORMING ORGANIZATION...Approved for Public Release; Distribution Unlimited. Carnegie Mellon Carnegie Mellon HA SPIRAL Code Synthesis KeYmaera X Hybrid Theorem Prover

  16. High assurance SPIRAL

    Science.gov (United States)

    Franchetti, Franz; Sandryhaila, Aliaksei; Johnson, Jeremy R.

    2014-06-01

    In this paper we introduce High Assurance SPIRAL to solve the last mile problem for the synthesis of high assurance implementations of controllers for vehicular systems that are executed in today's and future embedded and high performance embedded system processors. High Assurance SPIRAL is a scalable methodology to translate a high level specification of a high assurance controller into a highly resource-efficient, platform-adapted, verified control software implementation for a given platform in a language like C or C++. High Assurance SPIRAL proves that the implementation is equivalent to the specification written in the control engineer's domain language. Our approach scales to problems involving floating-point calculations and provides highly optimized synthesized code. It is possible to estimate the available headroom to enable assurance/performance trade-offs under real-time constraints, and enables the synthesis of multiple implementation variants to make attacks harder. At the core of High Assurance SPIRAL is the Hybrid Control Operator Language (HCOL) that leverages advanced mathematical constructs expressing the controller specification to provide high quality translation capabilities. Combined with a verified/certified compiler, High Assurance SPIRAL provides a comprehensive complete solution to the efficient synthesis of verifiable high assurance controllers. We demonstrate High Assurance SPIRALs capability by co-synthesizing proofs and implementations for attack detection and sensor spoofing algorithms and deploy the code as ROS nodes on the Landshark unmanned ground vehicle and on a Synthetic Car in a real-time simulator.

  17. Spiral silicon drift detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Gatti, E.; Longoni, A.; Sampietro, M.; Holl, P.; Lutz, G.; Kemmer, J.; Prechtel, U.; Ziemann, T.

    1988-01-01

    An advanced large area silicon photodiode (and x-ray detector), called Spiral Drift Detector, was designed, produced and tested. The Spiral Detector belongs to the family of silicon drift detectors and is an improvement of the well known Cylindrical Drift Detector. In both detectors, signal electrons created in silicon by fast charged particles or photons are drifting toward a practically point-like collection anode. The capacitance of the anode is therefore kept at the minimum (0.1pF). The concentric rings of the cylindrical detector are replaced by a continuous spiral in the new detector. The spiral geometry detector design leads to a decrease of the detector leakage current. In the spiral detector all electrons generated at the silicon-silicon oxide interface are collected on a guard sink rather than contributing to the detector leakage current. The decrease of the leakage current reduces the parallel noise of the detector. This decrease of the leakage current and the very small capacities of the detector anode with a capacitively matched preamplifier may improve the energy resolution of Spiral Drift Detectors operating at room temperature down to about 50 electrons rms. This resolution is in the range attainable at present only by cooled semiconductor detectors. 5 refs., 10 figs

  18. Gear ratting noise reduction of diesel engine; Diesel engine no gear hauchi soon teigen

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, S; Miura, Y [Hino Motors, Ltd., Tokyo (Japan)

    1997-10-01

    Gear raffling noise of diesel engine at idling condition is required to reduce for keeping quiet environment and comfort of driver and passengers on track and bus. Decrease of gear backlash is generally adopted for reducing gear rattling noise. On the other hand, it has been found that newly devised measurement of gear teeth speed and gear meshing error has clarified phenomena of gear rattling between the crankshaft gear and the camshaft gear of the diesel engine. And it has been also found that gear ratting noise is reduced by changing meshing between the crankshaft gear and the camshaft gear. 2 refs., 10 figs.

  19. 46 CFR 28.885 - Cargo gear.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Cargo gear. 28.885 Section 28.885 Shipping COAST GUARD... Aleutian Trade Act Vessels § 28.885 Cargo gear. (a) The safe working load (SWL) for the assembled gear... the load the gear is approved to lift, excluding the weight of the gear itself. (b) All wire rope...

  20. Double Helical Gear Performance Results in High Speed Gear Trains

    Science.gov (United States)

    Handschuh, Robert F.; Ehinger, Ryan; Sinusas, Eric; Kilmain, Charles

    2010-01-01

    The operation of high speed gearing systems in the transmissions of tiltrotor aircraft has an effect on overall propulsion system efficiency. Recent work has focused on many aspects of high-speed helical gear trains as would be used in tiltrotor aircraft such as operational characteristics, comparison of analytical predictions to experimental data and the affect of superfinishing on transmission performance. Baseline tests of an aerospace quality system have been conducted in the NASA Glenn High-Speed Helical Gear Train Test Facility and have been described in earlier studies. These earlier tests had utilized single helical gears. The results that will be described in this study are those attained using double helical gears. This type of gear mesh can be configured in this facility to either pump the air-oil environment from the center gap between the meshing gears to the outside of tooth ends or in the reverse direction. Tests were conducted with both inward and outward air-oil pumping directions. Results are compared to the earlier baseline results of single helical gears.

  1. High Pressure Angle Gears: Comparison to Typical Gear Designs

    Science.gov (United States)

    Handschuh, Robert F.; Zabrajsek, Andrew J.

    2010-01-01

    A preliminary study has been completed to determine the feasibility of using high-pressure angle gears in aeronautic and space applications. Tests were conducted in the NASA Glenn Research Center (GRC) Spur Gear Test Facility at speeds up to 10,000 rpm and 73 N*m (648 in.*lb) for 3.18, 2.12, and 1.59 module gears (8, 12, and 16 diametral pitch gears), all designed to operate in the same test facility. The 3.18 module (8-diametral pitch), 28 tooth, 20deg pressure angle gears are the GRC baseline test specimen. Also, 2.12 module (12-diametral pitch), 42 tooth, 25deg pressure angle gears were tested. Finally 1.59 module (16-diametral pitch), 56 tooth, 35deg pressure angle gears were tested. The high-pressure angle gears were the most efficient when operated in the high-speed aerospace mode (10,000 rpm, lubricated with a synthetic turbine engine oil), and produced the lowest wear rates when tested with a perfluoroether-based grease. The grease tests were conducted at 150 rpm and 71 N*m (630 in.*lb).

  2. Plasma Generator Using Spiral Conductors

    Science.gov (United States)

    Szatkowski, George N. (Inventor); Dudley, Kenneth L. (Inventor); Ticatch, Larry A. (Inventor); Smith, Laura J. (Inventor); Koppen, Sandra V. (Inventor); Nguyen, Truong X. (Inventor); Ely, Jay J. (Inventor)

    2016-01-01

    A plasma generator includes a pair of identical spiraled electrical conductors separated by dielectric material. Both spiraled conductors have inductance and capacitance wherein, in the presence of a time-varying electromagnetic field, the spiraled conductors resonate to generate a harmonic electromagnetic field response. The spiraled conductors lie in parallel planes and partially overlap one another in a direction perpendicular to the parallel planes. The geometric centers of the spiraled conductors define endpoints of a line that is non-perpendicular with respect to the parallel planes. A voltage source coupled across the spiraled conductors applies a voltage sufficient to generate a plasma in at least a portion of the dielectric material.

  3. Barred spiral structure of galaxies

    International Nuclear Information System (INIS)

    Chen, Z.; Weng, s.; Xu, M.

    1982-01-01

    Observational data indicate the grand design of spiral or barred spiral structure in disk galaxies. The problem of spiral structure has been thoroughly investigated by C. C. Lin and his collaborators, but yet the problem of barred spiral structure has not been investigated systematically, although much work has been done, such as in Ref. 3--7. Using the gasdynamic model for galaxies and a method of integral transform presented in Ref. 1, we investigated the barred spiral structure and obtained an analytical solution. It gives the large-scale pattern of barred-spirals, which is in fairly good agreement with observational data

  4. Design and construction of permanent magnetic gears

    DEFF Research Database (Denmark)

    Jørgensen, Frank Thorleif

    /l]. Measurement from this gear has resulted in a measured total torque density of 23 [Nm/l]. Mechanical versions of this gear type are found with total torque density in the 16 to 31 [Nm/l] range. The third and last gear technology that is investigated is a gear that reminds of a planetary gear. Research shows......This thesis deals with design and development of permanent magnetic gears. The goal of this thesis is to develop knowledge and calculation software for magnetic gears. They use strong NdFeB permanent magnets and a new magnetic gear technology, which will be a serious alternative to classical...... mechanical gears. The new magnetic gear will have a high torque density1 relationship –high efficiency and are maintenance free. In this project was manufactured two test gears which is tested and verified with models developed in this project. Present technological status for magnetic gears is introduced...

  5. Combined 30-degree bevel up and down technique against 0-degree phaco tip for phacoemulsification surgery of hard cataracts

    Directory of Open Access Journals (Sweden)

    Joshi RS

    2017-06-01

    Full Text Available Rajesh Subhash Joshi, Sonal Jayant Muley Department of Ophthalmology, Vasantrao Naik Government Medical College, Yavatmal, Maharashtra, India Purpose: To evaluate the effective phaco time (EPT, cumulative dissipated energy (CDE and nucleus emulsification time (NET as phaco parameters with 0- and 30-degree phaco tip. Patients and methods: This prospective, interventional and observational case series included 294 patients scheduled for cataract removal by phacoemulsification technique. Patients with nuclear cataracts of grade 4 and 5 nuclear opalescence of Lens Opacities Classification System III were included in the study. Patients were consecutively allocated to phaco chop technique with 0-degree (0-degree group, n=147 and combined bevel up and down position using 30-degree phaco tip (combined bevel up/down group, n=147. The 0-degree group had phacoemulsification with 0-degree phaco tip, while the 30-degree group had chopping of the nucleus with bevel down phaco tip and emulsification of nuclear fragments was accomplished with bevel up tip. EPT, CDE, NET and intraoperative complications were noted and compared between the groups using analysis of variance. Results: Average EPT, CDE and NET were lower in the 30-degree group than in the 0-degree group. However, no statistically significant difference was found in EPT (P=0.0733, CDE (P=0.0663 and NET (P=0.0633 between the two groups. No serious intraoperative complications were noted. The anterior chamber was maintained throughout the procedure in both groups. No patients had wound burn and miosis during the procedure. None of the patients developed bullous keratopathy, uveitis and cystoid macular edema during the follow-up period. Conclusion: Combined bevel up and down 30-degree tip can yield effective hard nucleus phacoemulsification. Bevel down tip of 30-degree helps in effective chopping and bevel up tip assists in emulsification of the nuclear fragments. Although combined bevel up and down 30

  6. Chiral Magnetic Spirals

    International Nuclear Information System (INIS)

    Basar, Goekce; Dunne, Gerald V.; Kharzeev, Dmitri E.

    2010-01-01

    We argue that the presence of a very strong magnetic field in the chirally broken phase induces inhomogeneous expectation values, of a spiral nature along the magnetic field axis, for the currents of charge and chirality, when there is finite baryon density or an imbalance between left and right chiralities. This 'chiral magnetic spiral' is a gapless excitation transporting the currents of (i) charge (at finite chirality), and (ii) chirality (at finite baryon density) along the direction of the magnetic field. In both cases it also induces in the transverse directions oscillating currents of charge and chirality. In heavy ion collisions, the chiral magnetic spiral possibly provides contributions both to the out-of-plane and the in-plane dynamical charge fluctuations recently observed at BNL RHIC.

  7. The Spiral of Euroscepticism

    DEFF Research Database (Denmark)

    Galpin, Charlotte; Trenz, Hans-Jörg

    2017-01-01

    of Euroscepticism’, taking media autonomy seriously to understand how media logics and selective devices contribute to the shaping of public discourse about the EU. We review the literature on the media and EU legitimacy to show how media frames and their amplification on social media can account for the salience......Media scholars have increasingly examined the effects of a negativity bias that applies to political news. In the ‘spiral of cynicism’, journalist preferences for negative news correspond to public demands for sensational news. We argue that this spiral of cynicism in EU news results in a ‘spiral...... of Eurosceptic opinions in the public sphere that then push parties to contest the EU in predominantly negative terms....

  8. Embracing the Spiral

    Directory of Open Access Journals (Sweden)

    Li Mao

    2016-12-01

    Full Text Available Critical research demands that we interrogate our own positionality and social location. Critical reflexivity is a form of researcher critical consciousness that is constant and dynamic in a complex spiral-like process starting within our own experiences as racialized, gendered, and classed beings embedded in particular sociopolitical contexts. Across diverse critical methodologies, a group of graduate students and their supervisor explored their own conceptualization of the reflexivity spiral by reflecting on how their research motivations and methodologies emerged from their racializing, colonizing, language-learning, parenting, and identity negotiating experiences. In this article, they present a spiral model of the critical reflexivity process, review the literature on reflexivity, and conclude with a description of critical reflexivity as a social practice within a supportive and collaborative graduate school experience.

  9. The spinning ball spiral

    International Nuclear Information System (INIS)

    Dupeux, Guillaume; Le Goff, Anne; Quere, David; Clanet, Christophe

    2010-01-01

    We discuss the trajectory of a fast revolving solid ball moving in a fluid of comparable density. As the ball slows down owing to drag, its trajectory follows an exponential spiral as long as the rotation speed remains constant: at the characteristic distance L where the ball speed is significantly affected by the drag, the bending of the trajectory increases, surprisingly. Later, the rotation speed decreases, which makes the ball follow a second kind of spiral, also described in the paper. Finally, the use of these highly curved trajectories is shown to be relevant to sports.

  10. Are spiral galaxies heavy smokers?

    International Nuclear Information System (INIS)

    Davies, J.; Disney, M.; Phillipps, S

    1990-01-01

    The dustiness of spiral galaxies is discussed. Starburst galaxies and the shortage of truly bright spiral galaxies is cited as evidence that spiral galaxies are far dustier than has been thought. The possibility is considered that the dust may be hiding missing mass

  11. Analysis of justification for applying two gear sets within the universal gear reducers

    OpenAIRE

    Rackov Milan; Kuzmanović Siniša; Knežević Ivan; Čavić Maja; Penčić Marko

    2017-01-01

    In the area of universal gear reducers, standard does not prescribe relations between load capacity, gear ratios and axis heights. Therefore, larger load capacity of some gear reducers manufacturers has advantage for lower gear ratio and, vice versa, smaller load capacity of the gearbox achieves higher values of gear ratio. However, there are some manufacturers who produce gear reducers with smaller or larger load capacity for higher or lower gear ratio, within the same axis height. This pape...

  12. Interlocking Molecular Gear Chains Built on Surfaces.

    Science.gov (United States)

    Zhao, Rundong; Qi, Fei; Zhao, Yan-Ling; Hermann, Klaus E; Zhang, Rui-Qin; Van Hove, Michel A

    2018-05-17

    Periodic chains of molecular gears in which molecules couple with each other and rotate on surfaces have been previously explored by us theoretically using ab initio simulation tools. On the basis of the knowledge and experience gained about the interactions between neighboring molecular gears, we here explore the transmission of rotational motion and energy over larger distances, namely, through a longer chain of gear-like passive "slave" molecules. Such microscopic gears exhibit quite different behaviors compared to rigid cogwheels in the macroscopic world due to their structural flexibility affecting intermolecular interaction. Here, we investigate the capabilities of such gear chains and reveal the mechanisms of the transmission process in terms of both quantum-level density functional theory (DFT) and simple classical mechanics. We find that the transmission of rotation along gear chains depends strongly on the gear-gear distance: short distances can cause tilting of gears and even irregular "creep-then-jump" (or "stick-slip") motion or expulsion of gears; long gear-gear distances cause weak coupling between gears, slipping and skipping. More importantly, for transmission of rotation at intermediate gear-gear distances, our modeling clearly exhibits the relative roles of several important factors: flexibility of gear arms, axles, and supports, as well as resulting rotational delays, slippages, and thermal and other effects. These studies therefore allow better informed design of future molecular machine components involving motors, gears, axles, etc.

  13. Properties of spiral resonators

    International Nuclear Information System (INIS)

    Haeuser, J.

    1989-10-01

    The present thesis deals with the calculation and the study of the application possibilities of single and double spiral resonators. The main aim was the development and the construction of reliable and effective high-power spiral resonators for the UNILAC of the GSI in Darmstadt and the H - -injector for the storage ring HERA of DESY in Hamburg. After the presentation of the construction and the properties of spiral resonators and their description by oscillating-circuit models the theoretical foundations of the bunching are presented and some examples of a rebuncher and debuncher and their influence on the longitudinal particle dynamics are shown. After the description of the characteristic accelerator quantities by means of an oscillating-circuit model and the theory of an inhomogeneous λ/4 line it is shown, how the resonance frequency and the efficiency of single and double spiral resonators can be calculated from the geometrical quantities of the structure. In the following the dependence of the maximal reachable resonator voltage in dependence on the gap width and the surface of the drift tubes is studied. Furthermore the high-power resonators are presented, which were built for the different applications for the GSI in Darmstadt, DESY in Hamburg, and for the FOM Institute in Amsterdam. (orig./HSI) [de

  14. Development in Geared Turbofan Aeroengine

    Science.gov (United States)

    Mohd Tobi, A. L.; Ismail, A. E.

    2016-05-01

    This paper looks into the implementation of epicyclic gear system to the aeroengine in order to increase the efficiency of the engine. The improvement made is in the direction of improving fuel consumption, reduction in pollutant gasses and perceived noise. Introduction of epicyclic gear system is capable to achieve bypass ratio of up to 15:1 with the benefits of weight and noise reduction. Radical new aircraft designs and engine installation are being studied to overcome some of the challenges associated with the future geared turbofan and open-rotor engine.

  15. 29 CFR 1918.54 - Rigging gear.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Rigging gear. 1918.54 Section 1918.54 Labor Regulations...) SAFETY AND HEALTH REGULATIONS FOR LONGSHORING Vessel's Cargo Handling Gear § 1918.54 Rigging gear. (a... other alternate device shall be provided to allow trimming of the gear and to prevent employees from...

  16. Tracking Target and Spiral Waves

    DEFF Research Database (Denmark)

    Jensen, Flemming G.; Sporring, Jon; Nielsen, Mads

    2002-01-01

    A new algorithm for analyzing the evolution of patterns of spiral and target waves in large aspect ratio chemical systems is introduced. The algorithm does not depend on finding the spiral tip but locates the center of the pattern by a new concept, called the spiral focus, which is defined...... by the evolutes of the actual spiral or target wave. With the use of Gaussian smoothing, a robust method is developed that permits the identification of targets and spirals foci independently of the wave profile. Examples of an analysis of long image sequences from experiments with the Belousov......–Zhabotinsky reaction catalyzed by ruthenium-tris-bipyridyl are presented. Moving target and spiral foci are found, and the speed and direction of movement of single as well as double spiral foci are investigated. For the experiments analyzed in this paper it is found that the movement of a focus correlates with foci...

  17. 50 CFR 648.84 - Gear-marking requirements and gear restrictions.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Gear-marking requirements and gear... Management Measures for the NE Multispecies and Monkfish Fisheries § 648.84 Gear-marking requirements and gear restrictions. (a) Bottom-tending fixed gear, including, but not limited to, gillnets and longlines...

  18. Modelling the Meshing of Cycloidal Gears

    Directory of Open Access Journals (Sweden)

    Nachimowicz Jerzy

    2016-06-01

    Full Text Available Cycloidal drives belong to the group of planetary gear drives. The article presents the process of modelling a cycloidal gear. The full profile of the planetary gear is determined from the following parameters: ratio of the drive, eccentricity value, the equidistant (ring gear roller radius, epicycloid reduction ratio, roller placement diameter in the ring gear. Joong-Ho Shin’s and Soon-Man Kwon’s article (Shin and Know, 2006 was used to determine the profile outline of the cycloidal planetary gear lobes. The result was a scatter chart with smooth lines and markers, presenting the full outline of the cycloidal gear.

  19. Forming Spirals From Shadows

    Science.gov (United States)

    Kohler, Susanna

    2016-07-01

    What causes the large-scale spiral structures found in some protoplanetary disks? Most models assume theyre created by newly-forming planets, but a new study suggests that planets might have nothing to do with it.Perturbations from Planets?In some transition disks protoplanetary disks with gaps in their inner regions weve directly imaged large-scale spiral arms. Many theories currently attribute the formation of these structures to young planets: either the direct perturbations of a planet embedded in the disk cause the spirals, or theyre indirectly caused by the orbit of a planetary body outside of the arms.Another example of spiral arms detected in a protoplanetary disk, MWC 758. [NASA/ESA/ESO/M. Benisty et al.]But what if you could get spirals without any planets? A team of scientists led by Matas Montesinos (University of Chile) have recently published a study in which they examine what happens to a shadowed protoplanetary disk.Casting Shadows with WarpsIn the teams setup, they envision a protoplanetary disk that is warped: the inner region is slightly tilted relative to the outer region. As the central star casts light out over its protoplanetary disk, this disk warping would cause some regions of the disk to be shaded in a way that isnt axially symmetric with potentially interesting implications.Montesinos and collaborators ran 2D hydrodynamics simulations to determine what happens to the motion of particles within the disk when they pass in and out of the shadowed regions. Since the shadowed regions are significantly colder than the illuminated disk, the pressure in these regions is much lower. Particles are therefore accelerated and decelerated as they pass through these regions, and the lack of axial symmetry causes spiral density waves to form in the disk as a result.Initial profile for the stellar heating rate per unit area for one of the authors simulations. The regions shadowed as a result of the disk warp subtend 0.5 radians each (shown on the left

  20. Theory of spiral structure

    International Nuclear Information System (INIS)

    Lin, C.C.

    1977-01-01

    The density wave theory of galactic spirals has now developed into a form suitable for consideration by experts in Applied Mechanics. On the one hand, comparison of theoretical deductions with observational data has convinced astrophysicists of the validity of the basic physical picture and the calculated results. On the other hand, the dynamical problems of a stellar system, such as those concerning the origin of spiral structure in galaxies, have not been completely solved. This paper reviews the current status of such developments, including a brief summary of comparison with observations. A particularly important mechanism, currently called the mechanism of energy exchange, is described in some detail. The mathematical problems and the physical processes involved are similar to those occurring in certain instability mechanisms in the 'magnetic bottle' designed for plasma containment. Speculations are given on the future developments of the theory and on observational programs. (Auth.)

  1. Spiral 2 workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The accelerator and experimental facilities at GANIL will be transformed over the next 5-10 years. The centerpiece of the additions to the accelerator complex will be Spiral-2. This is the first phase of a new radioactive beam facility based on the ISOL principle. The main aim of Spiral-2 will be to produce intense, high quality beams of neutron-rich nuclei created in neutron-induced fission of heavy elements and accelerated by the existing CIME cyclotron. The principal aims of this workshop will be a) to publicize the new facilities, b) to discuss and define the science which might be carried out with them, c) to discuss the instrumentation and infrastructure required to exploit the new facilities and d) to help form collaborations of scientists wishing to design and construct the equipment needed to undertake the science programme. This document gathers most of the slides presented in the workshop.

  2. Spiral nonimaging optical designs

    Science.gov (United States)

    Zamora, Pablo; Benítez, Pablo; Miñano, Juan C.; Vilaplana, Juan

    2011-10-01

    Manufacturing technologies as injection molding or embossing specify their production limits for minimum radii of the vertices or draft angle for demolding, for instance. In some demanding nonimaging applications, these restrictions may limit the system optical efficiency or affect the generation of undesired artifacts on the illumination pattern. A novel manufacturing concept is presented here, in which the optical surfaces are not obtained from the usual revolution symmetry with respect to a central axis (z axis), but they are calculated as free-form surfaces describing a spiral trajectory around z axis. The main advantage of this new concept lies in the manufacturing process: a molded piece can be easily separated from its mold just by applying a combination of rotational movement around axis z and linear movement along axis z, even for negative draft angles. Some of these spiral symmetry examples will be shown here, as well as their simulated results.

  3. Spiral 2 workshop

    International Nuclear Information System (INIS)

    2004-01-01

    The accelerator and experimental facilities at GANIL will be transformed over the next 5-10 years. The centerpiece of the additions to the accelerator complex will be Spiral-2. This is the first phase of a new radioactive beam facility based on the ISOL principle. The main aim of Spiral-2 will be to produce intense, high quality beams of neutron-rich nuclei created in neutron-induced fission of heavy elements and accelerated by the existing CIME cyclotron. The principal aims of this workshop will be a) to publicize the new facilities, b) to discuss and define the science which might be carried out with them, c) to discuss the instrumentation and infrastructure required to exploit the new facilities and d) to help form collaborations of scientists wishing to design and construct the equipment needed to undertake the science programme. This document gathers most of the slides presented in the workshop

  4. Holographic Chiral Magnetic Spiral

    International Nuclear Information System (INIS)

    Kim, Keun-Young; Sahoo, Bindusar; Yee, Ho-Ung

    2010-06-01

    We study the ground state of baryonic/axial matter at zero temperature chiral-symmetry broken phase under a large magnetic field, in the framework of holographic QCD by Sakai-Sugimoto. Our study is motivated by a recent proposal of chiral magnetic spiral phase that has been argued to be favored against previously studied phase of homogeneous distribution of axial/baryonic currents in terms of meson super-currents dictated by triangle anomalies in QCD. Our results provide an existence proof of chiral magnetic spiral in strong coupling regime via holography, at least for large axial chemical potentials, whereas we don't find the phenomenon in the case of purely baryonic chemical potential. (author)

  5. LHC preparations change gear

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    After the formal approval by CERN Council in December (January, page 1) of the LHC protonproton collider for CERN's 27- kilometre LEP tunnel, preparations for the new machine change gear. Lyndon Evans becomes LHC Project Leader, and CERN's internal structure will soon be reorganized to take account of the project becoming a definite commitment. On the experimental side, the full Technical Proposals for the big general purpose ATLAS and CMS detectors were aired at a major meeting of the LHC Committee at CERN in January. These Technical Proposals are impressive documents each of some several hundred pages. (Summaries of the detector designs will appear in forthcoming issues of the CERN Courier.) The ALICE heavy ion experiment is not far behind, and plans for other LHC experiments are being developed. Playing an important role in this groundwork has been the Detector Research and Development Committee (DRDC), founded in 1990 to foster detector development for the LHC experimental programme and structured along the lines of a traditional CERN Experiments Committee. Established under the Director Generalship of Carlo Rubbia and initially steered by Research Director Walter Hoogland, the DRDC has done sterling work in blazing a trail for LHC experiments. Acknowledging that the challenge of LHC experimentation needs technological breakthroughs as well as specific detector subsystems, DRDC proposals have covered a wide front, covering readout electronics and computing as well as detector technology. Its first Chairman was Enzo larocci, succeeded in 1993 by Michal Turala. DRDC's role was to evaluate proposals, and make recommendations to CERN's Research Board for approval and resource allocation, not an easy task when the LHC project itself had yet to be formally approved. Over the years, a comprehensive portfolio of detector development has been built up, much of which has either led to specific LHC detector subsystems for traditional detector tasks

  6. Band-notched spiral antenna

    Science.gov (United States)

    Jeon, Jae; Chang, John

    2018-03-13

    A band-notched spiral antenna having one or more spiral arms extending from a radially inner end to a radially outer end for transmitting or receiving electromagnetic radiation over a frequency range, and one or more resonance structures positioned adjacent one or more segments of the spiral arm associated with a notch frequency band or bands of the frequency range so as to resonate and suppress the transmission or reception of electromagnetic radiation over said notch frequency band or bands.

  7. Nature of galaxy spiral arms

    International Nuclear Information System (INIS)

    Efremov, Yu.N.

    1984-01-01

    The nature of galaxy spiral arms is discussed in a popular form. Two approaches in the theory of spiral arms are considered; they are related to the problem of differential galaxy rotation and the spiral structure wave theory. The example of Galaxy M31 is considered to compare the structural peculiarity of its spiral arms with the wave theory predictions. The situation in the central and south-eastern part of arm S4 in Galaxy M31 noted to be completely explained by the wave theory and modern concepts on the origin of massive stars

  8. Measuring nutrient spiralling in streams

    Energy Technology Data Exchange (ETDEWEB)

    Newbold, J D; Elwood, J W; O' Neill, R V; Van Winkle, W

    1981-01-01

    Nutrient cycling in streams involves some downstream transport before the cycle is completed. Thus, the path traveled by a nutrient atom in passing through the cycle can be visualized as a spiral. As an index of the spiralling process, we introduce spiralling length, defined as the average distance associated with one complete cycle of a nutrient atom. This index provides a measure of the utilization of nutrients relative to the available supply from upstream. Using /sup 32/p as a tracer, we estimated a spiralling length of 193 m for phosphorus in a small woodland stream.

  9. Three phase spiral liver Scanning

    International Nuclear Information System (INIS)

    Kanyanja, T.A.

    2006-01-01

    The ability to perform rapid back-to-back spiral acquisitions is an important recent technical advantage of spiral CT. this allows imaging of the upper abdomen (liver) during peak arterial enhancement (arterial phase) and during peak hepatic parenchymal enhancement (portal venous phase). Breatheld spiral CT has completely replaced dynamic incremental CT for evaluation of the liver. in selected patients with hyper vascular metastasis (hepatoma, neuroendocrine tumors, renal cell carcinoma, etc.) a biphasic examination is performed with one spiral acquisition obtained during the hepatic arterial phase and a second acquisition during the portal venous phase

  10. Theory of gearing kinematics, geometry, and synthesis

    CERN Document Server

    Radzevich, Stephen P

    2012-01-01

    The first book of its kind, Theory of Gearing: Kinematics, Geometry, and Synthesis systematically develops a scientific theory of gearing that makes it possible to synthesize novel gears with the desired performance. Written by a leading gearing expert who holds more than 200 patents, it presents a modern methodology for gear design. The proposed theory is based on a key postulate: all the design parameters for an optimal gear pair for a particular application can be derived from (a) a given configuration of the rotation vectors of the driving and driven shafts and (b) the power transmitted by

  11. Advanced Face Gear Surface Durability Evaluations

    Science.gov (United States)

    Lewicki, David G.; Heath, Gregory F.

    2016-01-01

    The surface durability life of helical face gears and isotropic super-finished (ISF) face gears was investigated. Experimental fatigue tests were performed at the NASA Glenn Research Center. Endurance tests were performed on 10 sets of helical face gears in mesh with tapered involute helical pinions, and 10 sets of ISF-enhanced straight face gears in mesh with tapered involute spur pinions. The results were compared to previous tests on straight face gears. The life of the ISF configuration was slightly less than that of previous tests on straight face gears. The life of the ISF configuration was slightly greater than that of the helical configuration.

  12. The subtropical nutrient spiral

    Science.gov (United States)

    Jenkins, William J.; Doney, Scott C.

    2003-12-01

    We present an extended series of observations and more comprehensive analysis of a tracer-based measure of new production in the Sargasso Sea near Bermuda using the 3He flux gauge technique. The estimated annually averaged nitrate flux of 0.84 ± 0.26 mol m-2 yr-1 constitutes only that nitrate physically transported to the euphotic zone, not nitrogen from biological sources (e.g., nitrogen fixation or zooplankton migration). We show that the flux estimate is quantitatively consistent with other observations, including decade timescale evolution of the 3H + 3He inventory in the main thermocline and export production estimates. However, we argue that the flux cannot be supplied in the long term by local diapycnal or isopycnal processes. These considerations lead us to propose a three-dimensional pathway whereby nutrients remineralized within the main thermocline are returned to the seasonally accessible layers within the subtropical gyre. We describe this mechanism, which we call "the nutrient spiral," as a sequence of steps where (1) nutrient-rich thermocline waters are entrained into the Gulf Stream, (2) enhanced diapycnal mixing moves nutrients upward onto lighter densities, (3) detrainment and enhanced isopycnal mixing injects these waters into the seasonally accessible layer of the gyre recirculation region, and (4) the nutrients become available to biota via eddy heaving and wintertime convection. The spiral is closed when nutrients are utilized, exported, and then remineralized within the thermocline. We present evidence regarding the characteristics of the spiral and discuss some implications of its operation within the biogeochemical cycle of the subtropical ocean.

  13. Rebuilding Spiral Galaxies

    Science.gov (United States)

    2005-01-01

    Major Observing Programme Leads to New Theory of Galaxy Formation Summary Most present-day large galaxies are spirals, presenting a disc surrounding a central bulge. Famous examples are our own Milky Way or the Andromeda Galaxy. When and how did these spiral galaxies form? Why do a great majority of them present a massive central bulge? An international team of astronomers [1] presents new convincing answers to these fundamental questions. For this, they rely on an extensive dataset of observations of galaxies taken with several space- and ground-based telescopes. In particular, they used over a two-year period, several instruments on ESO's Very Large Telescope. Among others, their observations reveal that roughly half of the present-day stars were formed in the period between 8,000 million and 4,000 million years ago, mostly in episodic burst of intense star formation occurring in Luminous Infrared Galaxies. From this and other evidence, the astronomers devised an innovative scenario, dubbed the "spiral rebuilding". They claim that most present-day spiral galaxies are the results of one or several merger events. If confirmed, this new scenario could revolutionise the way astronomers think galaxies formed. PR Photo 02a/05: Luminosity - Oxygen Abundance Relation for Galaxies (VLT) PR Photo 02b/05: The Spiral Rebuilding Scenario A fleet of instruments How and when did galaxies form? How and when did stars form in these island universes? These questions are still posing a considerable challenge to present-day astronomers. Front-line observational results obtained with a fleet of ground- and space-based telescopes by an international team of astronomers [1] provide new insights into these fundamental issues. For this, they embarked on an ambitious long-term study at various wavelengths of 195 galaxies with a redshift [2] greater than 0.4, i.e. located more than 4000 million light-years away. These galaxies were studied using ESO's Very Large Telescope, as well as the

  14. Advanced theories of hypoid gears

    CERN Document Server

    Wang, Xudong

    2013-01-01

    In order to develop more efficient types of gears, further investigation into the theories of engagement is necessary. Up until now most of the research work on the theories of engagement has been carried out separately on different groups, and based on individual types of profiles. This book aims at developing some universal theories, which can not only be used for all types of gears, but can also be utilized in other fields such as sculptured surfaces. The book has four characteristics: the investigations are concentrated on mismatched tooth surfaces; all the problems are dealt with from a

  15. Induction Hardening of External Gear

    Science.gov (United States)

    Bukanin, V. A.; Ivanov, A. N.; Zenkov, A. E.; Vologdin, V. V.; Vologdin, V. V., Jr.

    2018-03-01

    Problems and solution of gear induction hardening are described. Main attention is paid to the parameters of heating and cooling systems. ELTA 7.0 program has been used to obtain the required electrical parameters of inductor, power sources, resonant circuits, as well as to choose the quenching media. Comparison of experimental and calculated results of investigation is provided. In order to compare advantages and disadvantages of single- and dual-frequency heating processes, many variants of these technologies were simulated. The predicted structure and hardness of steel gears are obtained by use of the ELTA data base taken into account the Continuous Cooling Transformation diagrams.

  16. Spiral branches and star formation

    International Nuclear Information System (INIS)

    Zasov, A.V.

    1974-01-01

    Origin of spiral branches of galaxies and formation of stars in them are considered from the point of view of the theory of the gravitational gas condensation, one of comparatively young theories. Arguments are presented in favour of the stellar condensation theory. The concept of the star formation of gas is no longer a speculative hypothesis. This is a theory which assumes quantitative verification and explains qualitatively many facts observed. And still our knowledge on the nature of spiral branches is very poor. It still remains vague what processes give origin to spiral branches, why some galaxies have spirals and others have none. And shapes of spiral branches are diverse. Some cases are known when spiral branches spread outside boundaries of galaxies themselves. Such spirals arise exclusively in the region where there are two or some interacting galaxies. Only first steps have been made in the explanation of the galaxy spiral branches, and it is necessary to carry out new observations and new theoretical calculations

  17. Global extinction in spiral galaxies

    NARCIS (Netherlands)

    Tully, RB; Pierce, MJ; Saunders, W; Verheijen, MAW; Witchalls, PL

    Magnitude-limited samples of spiral galaxies drawn from the Ursa Major and Pisces Clusters are used to determine their extinction properties as a function of inclination. Imaging photometry is available for 87 spirals in the B, R, I, and K' bands. Extinction causes systematic scatter in

  18. The perfect shape spiral stories

    CERN Document Server

    Hammer, Øyvind

    2016-01-01

    This book uses the spiral shape as a key to a multitude of strange and seemingly disparate stories about art, nature, science, mathematics, and the human endeavour. In a way, the book is itself organized as a spiral, with almost disconnected chapters circling around and closing in on the common theme. A particular strength of the book is its extremely cross-disciplinary nature - everything is fun, and everything is connected! At the same time, the author puts great emphasis on mathematical and scientific correctness, in contrast, perhaps, with some earlier books on spirals. Subjects include the mathematical properties of spirals, sea shells, sun flowers, Greek architecture, air ships, the history of mathematics, spiral galaxies, the anatomy of the human hand, the art of prehistoric Europe, Alfred Hitchcock, and spider webs, to name a few.

  19. GEAR UP Aspirations Project Evaluation

    Science.gov (United States)

    Trimble, Brad A.

    2013-01-01

    The purpose of this study was to conduct a formative evaluation of the first two years of the Gaining Early Awareness and Readiness for Undergraduate Programs (GEAR UP) Aspirations Project (Aspirations) using a Context, Input, Process, and Product (CIPP) model so as to gain an in-depth understanding of the project during the middle school…

  20. Lopsided spiral galaxies

    International Nuclear Information System (INIS)

    Jog, Chanda J.; Combes, Francoise

    2009-01-01

    The light distribution in the disks of many galaxies is 'lopsided' with a spatial extent much larger along one half of a galaxy than the other, as seen in M101. Recent observations show that the stellar disk in a typical spiral galaxy is significantly lopsided, indicating asymmetry in the disk mass distribution. The mean amplitude of lopsidedness is 0.1, measured as the Fourier amplitude of the m=1 component normalized to the average value. Thus, lopsidedness is common, and hence it is important to understand its origin and dynamics. This is a new and exciting area in galactic structure and dynamics, in contrast to the topic of bars and two-armed spirals (m=2) which has been extensively studied in the literature. Lopsidedness is ubiquitous and occurs in a variety of settings and tracers. It is seen in both stars and gas, in the outer disk and the central region, in the field and the group galaxies. The lopsided amplitude is higher by a factor of two for galaxies in a group. The lopsidedness has a strong impact on the dynamics of the galaxy, its evolution, the star formation in it, and on the growth of the central black hole and on the nuclear fuelling. We present here an overview of the observations that measure the lopsided distribution, as well as the theoretical progress made so far to understand its origin and properties. The physical mechanisms studied for its origin include tidal encounters, gas accretion and a global gravitational instability. The related open, challenging problems in this emerging area are discussed

  1. Arsia Mons Spiral Cloud

    Science.gov (United States)

    2002-01-01

    One of the benefits of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) Extended Mission is the opportunity to observe how the planet's weather changes during a second full martian year. This picture of Arsia Mons was taken June 19, 2001; southern spring equinox occurred the same day. Arsia Mons is a volcano nearly large enough to cover the state of New Mexico. On this particular day (the first day of Spring), the MOC wide angle cameras documented an unusual spiral-shaped cloud within the 110 km (68 mi) diameter caldera--the summit crater--of the giant volcano. Because the cloud is bright both in the red and blue images acquired by the wide angle cameras, it probably consisted mostly of fine dust grains. The cloud's spin may have been induced by winds off the inner slopes of the volcano's caldera walls resulting from the temperature differences between the walls and the caldera floor, or by a vortex as winds blew up and over the caldera. Similar spiral clouds were seen inside the caldera for several days; we don't know if this was a single cloud that persisted throughout that time or one that regenerated each afternoon. Sunlight illuminates this scene from the left/upper left.Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

  2. Feasibility of attaining uniform grain structure and enhanced ductility in aluminum alloy by employing a beveled punch in equal-channel angular pressing

    Energy Technology Data Exchange (ETDEWEB)

    Nejadseyfi, Omid, E-mail: o.nejadseyfi@gmail.com [Advanced Materials and Nanotechnology Research Lab, Department of Mechanical Engineering, K.N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Shokuhfar, Ali [Advanced Materials and Nanotechnology Research Lab, Department of Mechanical Engineering, K.N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Sadeghi, Seyedali [Department of Mechanical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

    2016-01-10

    The advantage of using a beveled-edge punch in equal-channel angular pressing is investigated. Lambda angle (λ), the clockwise angle between the theoretical shear plane and punch/billet interface, is used to demonstrate how the punch tip is inclined. Transmission electron microscope is used to assess the microstructure of the samples processed using a beveled-edge punch. In addition, tensile tests at elevated temperature are performed. The results show that using a beveled-edge punch (λ=90°) in the process leads to formation of uniform subgrain structure and increases the tensile ductility for the samples at elevated temperature. Additionally, finite element simulations are performed to study the correlation between measured properties and mechanism of material deformation by employing a beveled-edge punch. Numerical simulations confirm the irregular deformation in case of λ=0° and uniform strain distribution for λ=90°, which were the main reasons of variation in mechanical properties.

  3. Beveled fiber-optic probe couples a ball lens for improving depth-resolved fluorescence measurements of layered tissue: Monte Carlo simulations

    International Nuclear Information System (INIS)

    Jaillon, Franck; Zheng Wei; Huang Zhiwei

    2008-01-01

    In this study, we evaluate the feasibility of designing a beveled fiber-optic probe coupled with a ball lens for improving depth-resolved fluorescence measurements of epithelial tissue using Monte Carlo (MC) simulations. The results show that by using the probe configuration with a beveled tip collection fiber and a flat tip excitation fiber associated with a ball lens, discrimination of fluorescence signals generated in different tissue depths is achievable. In comparison with a flat-tip collection fiber, the use of a large bevel angled collection fiber enables a better differentiation between the shallow and deep tissue layers by changing the excitation-collection fiber separations. This work suggests that the beveled fiber-optic probe coupled with a ball lens has the potential to facilitate depth-resolved fluorescence measurements of epithelial tissues

  4. Polarization study of spiral galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Ward-Thompson, D

    1987-01-01

    Optical polarimetry results are presented for four spiral galaxies: NGC 5194 (M51), NGC 1068, NGC 4565 and NGC 4594 (M104). M51 and NGC 1068 show spiral polarization patterns interpreted as indicating a spiral magnetic field in each case. NGC 4565 and M104 show polarizations in their dust lanes which are parallel to their galactic planes, and which are interpreted in terms of a magnetic field in the plane of each. It is hypothesized that the observed magnetic fields may be linked to galactic shocks. A discussion of the origin of galactic magnetic fields concludes that there is not evidence that necessitates a primordial magnetic field.

  5. Spiral phases of doped antiferromagnets

    International Nuclear Information System (INIS)

    Shraiman, B.I.; Siggia, E.D.

    1990-01-01

    The dipole density field describing the holls in a doped antiferromagnet is considered for law hole density in the semiclassical limit. This yields a phase in which the order parameter is planar and spirals round a fixed direction. The single spiral state breaks the continuous spin rotational symmetry and exhibits long-range order at zero temperature. In it there is a global spin direction as rotation axis. The double spiral state, in which there are two perpendicular directions, is isotropic in both spin and real space. Several results of microscopic calculations, carried out to understand the electronic states, quantum fluctuations, lattice effects and normal mode dynamics, are recapitulated. 8 refs

  6. Parametric surface and properties defined on parallelogrammic domain

    Directory of Open Access Journals (Sweden)

    Shuqian Fan

    2014-01-01

    Full Text Available Similar to the essential components of many mechanical systems, the geometrical properties of the teeth of spiral bevel gears greatly influence the kinematic and dynamic behaviors of mechanical systems. Logarithmic spiral bevel gears show a unique advantage in transmission due to their constant spiral angle property. However, a mathematical model suitable for accurate digital modeling, differential geometrical characteristics, and related contact analysis methods for tooth surfaces have not been deeply investigated, since such gears are not convenient in traditional cutting manufacturing in the gear industry. Accurate mathematical modeling of the tooth surface geometry for logarithmic spiral bevel gears is developed in this study, based on the basic gearing kinematics and spherical involute geometry along with the tangent planes geometry; actually, the tooth surface is a parametric surface defined on a parallelogrammic domain. Equivalence proof of the tooth surface geometry is then given in order to greatly simplify the mathematical model. As major factors affecting the lubrication, surface fatigue, contact stress, wear, and manufacturability of gear teeth, the differential geometrical characteristics of the tooth surface are summarized using classical fundamental forms. By using the geometrical properties mentioned, manufactura-bility (and its limitation in logarithmic spiral bevel gears is analyzed using precision forging and multi-axis freeform milling, rather than classical cradle-type machine tool based milling or hobbing. Geometry and manufacturability analysis results show that logarithmic spiral gears have many application advantages, but many urgent issues such as contact tooth analysis for precision plastic forming and multi-axis freeform milling also need to be solved in a further study.

  7. Spiral-shaped disinfection reactors

    KAUST Repository

    Ghaffour, NorEddine; Ait-Djoudi, Fariza; Naceur, Wahib Mohamed; Soukane, Sofiane

    2015-01-01

    This disclosure includes disinfection reactors and processes for the disinfection of water. Some disinfection reactors include a body that defines an inlet, an outlet, and a spiral flow path between the inlet and the outlet, in which the body

  8. Spiral-shaped disinfection reactors

    KAUST Repository

    Ghaffour, Noreddine

    2015-08-20

    This disclosure includes disinfection reactors and processes for the disinfection of water. Some disinfection reactors include a body that defines an inlet, an outlet, and a spiral flow path between the inlet and the outlet, in which the body is configured to receive water and a disinfectant at the inlet such that the water is exposed to the disinfectant as the water flows through the spiral flow path. Also disclosed are processes for disinfecting water in such disinfection reactors.

  9. Design of Gear Churning Power Loss Measurement Device

    OpenAIRE

    Wang Bin; Zhou Ya Jie; Wang Ping

    2017-01-01

    To explore the impacts of gear churning power losses, a research was conducted to achieve the internal causes of power losses of churning gear by designing a gear churning power losses measurement device. The gear churning power losses could be influenced by different gear modules, the number of teeth and the axial position of gear. Finally, the impacts of gear churning power losses were discussed by comparing experimental data and theoretical data.

  10. Investigation on wear characteristic of biopolymer gear

    Science.gov (United States)

    Ghazali, Wafiuddin Bin Md; Daing Idris, Daing Mohamad Nafiz Bin; Sofian, Azizul Helmi Bin; Basrawi, Mohamad Firdaus bin; Khalil Ibrahim, Thamir

    2017-10-01

    Polymer is widely used in many mechanical components such as gear. With the world going to a more green and sustainable environment, polymers which are bio based are being recognized as a replacement for conventional polymers based on fossil fuel. The use of biopolymer in mechanical components especially gear have not been fully explored yet. This research focuses on biopolymer for spur gear and whether the conventional method to investigate wear characteristic is applicable. The spur gears are produced by injection moulding and tested on several speeds using a custom test equipment. The wear formation such as tooth fracture, tooth deformation, debris and weight loss was observed on the biopolymer spur gear. It was noted that the biopolymer gear wear mechanism was similar with other type of polymer spur gears. It also undergoes stages of wear which are; running in, linear and rapid. It can be said that the wear mechanism of biopolymer spur gear is comparable to fossil fuel based polymer spur gear, thus it can be considered to replace polymer gears in suitable applications.

  11. Micro-Raman depth profile investigations of beveled Al+-ion implanted 6H-SiC samples

    International Nuclear Information System (INIS)

    Zuk, J.; Romanek, J.; Skorupa, W.

    2009-01-01

    6H-SiC single crystals were implanted with 450 keV Al + -ions to a fluence of 3.4 x 10 15 cm -2 , and in a separate experiment subjected to multiple Al + implantations with the four energies: 450, 240, 115 and 50 keV and different fluences to obtain rectangular-like depth distributions of Al in SiC. The implantations were performed along [0 0 0 1] channeling and non-channeling ('random') directions. Subsequently, the samples were annealed for 10 min at 1650 deg. C in an argon atmosphere. The depth profiles of the implanted Al atoms were obtained by secondary ion mass spectrometry (SIMS). Following implantation and annealing, the samples were beveled by mechanical polishing. Confocal micro-Raman spectroscopic investigations were performed with a 532 nm wavelength laser beam of a 1 μm focus diameter. The technique was used to determine precisely the depth profiles of TO and LO phonon lines intensity in the beveled samples to a depth of about 2000 nm. Micro-Raman spectroscopy was also found to be useful in monitoring very low levels of disorder remaining in the Al + implanted and annealed 6H-SiC samples. The micro-Raman technique combined with sample beveling also made it possible the determination of optical absorption coefficient profiles in implanted subsurface layers.

  12. Reduction of belt CVT gear noise by gear train modification. Optimize vibration characteristics of gear train; Belt CVT no gear noise teigen gijutsu. Gear train shindo tokusei no saitekika

    Energy Technology Data Exchange (ETDEWEB)

    Arimatsu, M; Kawakami, T [Nissan Motor Co. Ltd., Tokyo (Japan)

    1997-10-01

    With the reduction of vehicle noise, the requirements for an efficient method to reduce transmission gear noise have become stronger yearly. So far efforts to reduce gear noise have generally focused on ways of improving the gears themselves. In addition to these traditional methods, it proved very beneficial to us to optimize the gear train structure. Nissan has just released the new Belt CVT for 2.0L Front wheel drive vehicles. We have been analyzing vibration of the gear train by using a finite element model since the early development stage, and we could achieve the quiet gears effectively. 2 refs., 9 figs.

  13. Gear failure of a PHWR refuelling machine

    International Nuclear Information System (INIS)

    Iorio, A.F.; Crespi, J.C.

    1986-01-01

    After ten year service in Atucha Nuclear Station a gear belonging to a pressurized heavy water reactor refuelling machine, failed. The gear box was used to transmit motion to the inlet-outlet heavy-water valve of that machine. Visual examination of the gear device revealed an absence of lubricant and several gear teeth were broken off at the root. The gear motion was transmitted from a speed-reducing device with controlled adjustable times in order to produce a right fitness of the valve closure. The main cause of gear failure was due to misalignment produced during assembly or in-service operation. It is suggested to control periodically the level of oil lubricant. (orig./IHOE) [de

  14. Lubrication and cooling for high speed gears

    Science.gov (United States)

    Townsend, D. P.

    1985-01-01

    The problems and failures occurring with the operation of high speed gears are discussed. The gearing losses associated with high speed gearing such as tooth mesh friction, bearing friction, churning, and windage are discussed with various ways shown to help reduce these losses and thereby improve efficiency. Several different methods of oil jet lubrication for high speed gearing are given such as into mesh, out of mesh, and radial jet lubrication. The experiments and analytical results for the various methods of oil jet lubrication are shown with the strengths and weaknesses of each method discussed. The analytical and experimental results of gear lubrication and cooling at various test conditions are presented. These results show the very definite need of improved methods of gear cooling at high speed and high load conditions.

  15. 29 CFR 1919.19 - Gear requiring welding.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Gear requiring welding. 1919.19 Section 1919.19 Labor... (CONTINUED) GEAR CERTIFICATION Certification of Vessels' Cargo Gear § 1919.19 Gear requiring welding. Chains or other gear which have been lengthened, altered or repaired by welding shall be properly heat...

  16. 50 CFR 697.23 - Restricted gear areas.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Restricted gear areas. 697.23 Section 697... Measures § 697.23 Restricted gear areas. (a) Resolution of lobster gear conflicts with fisheries managed...) Restricted Gear Area I—(1) Duration—(i) Mobile Gear. From October 1 through June 15 of each fishing year, no...

  17. A Circularly Arranged Sextuple Triptycene Gear Molecule.

    Science.gov (United States)

    Ube, Hitoshi; Yamada, Ryo; Ishida, Jun-Ichi; Sato, Hiroyasu; Shiro, Motoo; Shionoya, Mitsuhiko

    2017-11-22

    Herein we report the synthesis of a circularly arranged sextuple triptycene gear molecule, hexakis(10-dodecyloxy-9-triptycyl)ethynylbenzene, via the trimerization of the corresponding triyne with a cobalt catalyst. The six triptycene gears are closely engaged with each other as confirmed by single crystal X-ray structure analysis, and their motion in solution was established by NMR spectroscopy. Notably, when one bulky RuCp* complex was attached to one triptycene gear, the whole movement of the six gears was highly restricted via their mechanical engagement. Development of such a multigear molecule would provide a structural basis for molecular motion transmission systems with a switching function.

  18. Linear dynamic coupling in geared rotor systems

    Science.gov (United States)

    David, J. W.; Mitchell, L. D.

    1986-01-01

    The effects of high frequency oscillations caused by the gear mesh, on components of a geared system that can be modeled as rigid discs are analyzed using linear dynamic coupling terms. The coupled, nonlinear equations of motion for a disc attached to a rotating shaft are presented. The results of a trial problem analysis show that the inclusion of the linear dynamic coupling terms can produce significant changes in the predicted response of geared rotor systems, and that the produced sideband responses are greater than the unbalanced response. The method is useful in designing gear drives for heavy-lift helicopters, industrial speed reducers, naval propulsion systems, and heavy off-road equipment.

  19. Razón de contacto total en los engranajes cónicos circulares. // Contact Rate in circular Bevel gears.

    OpenAIRE

    E. Mirabet Lemos; L. Martínez Delgado

    2006-01-01

    En el presente trabajo se realiza un análisis deductivo de las expresiones que permiten evaluar la razón de contacto total enlos engranajes cónicos circulares. Dicho análisis se ha realizado haciendo uso de la transmisión cilíndrica virtual.Se obtienen dos formulas equivalentes, pero que se diferencian en algunos de los parámetros que las conforman. Cada unade estas formulas esta basada en formas diferentes de analizar la razón de contacto total y en particular uno de suscomponentes, la razón...

  20. Load Sharing Behavior of Star Gearing Reducer for Geared Turbofan Engine

    Science.gov (United States)

    Mo, Shuai; Zhang, Yidu; Wu, Qiong; Wang, Feiming; Matsumura, Shigeki; Houjoh, Haruo

    2017-07-01

    Load sharing behavior is very important for power-split gearing system, star gearing reducer as a new type and special transmission system can be used in many industry fields. However, there is few literature regarding the key multiple-split load sharing issue in main gearbox used in new type geared turbofan engine. Further mechanism analysis are made on load sharing behavior among star gears of star gearing reducer for geared turbofan engine. Comprehensive meshing error analysis are conducted on eccentricity error, gear thickness error, base pitch error, assembly error, and bearing error of star gearing reducer respectively. Floating meshing error resulting from meshing clearance variation caused by the simultaneous floating of sun gear and annular gear are taken into account. A refined mathematical model for load sharing coefficient calculation is established in consideration of different meshing stiffness and supporting stiffness for components. The regular curves of load sharing coefficient under the influence of interactions, single action and single variation of various component errors are obtained. The accurate sensitivity of load sharing coefficient toward different errors is mastered. The load sharing coefficient of star gearing reducer is 1.033 and the maximum meshing force in gear tooth is about 3010 N. This paper provides scientific theory evidences for optimal parameter design and proper tolerance distribution in advanced development and manufacturing process, so as to achieve optimal effects in economy and technology.

  1. Orientation decoding: Sense in spirals?

    Science.gov (United States)

    Clifford, Colin W G; Mannion, Damien J

    2015-04-15

    The orientation of a visual stimulus can be successfully decoded from the multivariate pattern of fMRI activity in human visual cortex. Whether this capacity requires coarse-scale orientation biases is controversial. We and others have advocated the use of spiral stimuli to eliminate a potential coarse-scale bias-the radial bias toward local orientations that are collinear with the centre of gaze-and hence narrow down the potential coarse-scale biases that could contribute to orientation decoding. The usefulness of this strategy is challenged by the computational simulations of Carlson (2014), who reported the ability to successfully decode spirals of opposite sense (opening clockwise or counter-clockwise) from the pooled output of purportedly unbiased orientation filters. Here, we elaborate the mathematical relationship between spirals of opposite sense to confirm that they cannot be discriminated on the basis of the pooled output of unbiased or radially biased orientation filters. We then demonstrate that Carlson's (2014) reported decoding ability is consistent with the presence of inadvertent biases in the set of orientation filters; biases introduced by their digital implementation and unrelated to the brain's processing of orientation. These analyses demonstrate that spirals must be processed with an orientation bias other than the radial bias for successful decoding of spiral sense. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. The Dilemma of Derelict Gear.

    Science.gov (United States)

    Scheld, A M; Bilkovic, D M; Havens, K J

    2016-01-21

    Every year, millions of pots and traps are lost in crustacean fisheries around the world. Derelict fishing gear has been found to produce several harmful environmental and ecological effects, however socioeconomic consequences have been investigated less frequently. We analyze the economic effects of a substantial derelict pot removal program in the largest estuary of the United States, the Chesapeake Bay. By combining spatially resolved data on derelict pot removals with commercial blue crab (Callinectes sapidus) harvests and effort, we show that removing 34,408 derelict pots led to significant gains in gear efficiency and an additional 13,504 MT in harvest valued at US $21.3 million--a 27% increase above that which would have occurred without removals. Model results are extended to a global analysis where it is seen that US $831 million in landings could be recovered annually by removing less than 10% of the derelict pots and traps from major crustacean fisheries. An unfortunate common pool externality, the degradation of marine environments is detrimental not only to marine organisms and biota, but also to those individuals and communities whose livelihoods and culture depend on profitable and sustainable marine resource use.

  3. Involute Spur Gear Template Development by Parametric Technique ...

    African Journals Online (AJOL)

    Nekky Umera

    cylindrical coordinate systems to create the involute curve profile. Since spur gear ... Template gear development using parametric method means that the dimensions control the ... and rapid prototyping of interlocking gears. Excel is a common ...

  4. VARIABLE MESH STIFFNESS OF SPUR GEAR TEETH USING ...

    African Journals Online (AJOL)

    gear engagement. A gear mesh kinematic simulation ... model is appropnate for VMS of a spur gear tooth. The assumptions for ... This process has been continued until one complete tooth meshing cycle is ..... Element Method. Using MATLAB,.

  5. Origins of galactic spiral structures

    International Nuclear Information System (INIS)

    Piddington, J.H.

    1978-01-01

    Theories of galactic structure are reviewed briefly before comparing them with recent observations. Also reviewed is the evidence for an intergalactic magnetic field and its possible effects on gas concentrations and patterns of star creation, including spiral arms. It is then shown that normal spiral galaxies may be divided into the M51-type and others. The rare M51-type have H I gas arms coincident with unusually filamentary and luminous optical arms; they also have a companion galaxy. The remaining great majority of spirals have no well-defined gas arms and their optical arms are irregular, broader and less luminous; they have no companion galaxy. It appears that without exception the half-dozen or so galaxies whose structures appear to support the density-wave theory show one or more of the characteristics of the rare type of spiral, and that 'the three principal confirmations of the spiral-wave idea' (M51, M81, M101) have companions which may account for their arms. Toomre has rejected this idea on the grounds that his models do not agree with the observed structures. It is shown that these models are inadequate in two major respects, and when replaced by magneto-tidal models using non-uniform gas disks one might expect agreement. The original hydromagnetic model of spiral arms is now reserved for non-interacting galaxies, of which M33 might be taken as a prototype. The model predicts broad or 'massive' optical arms and no corresponding arms of neutral hydrogen, as observed. (Auth.)

  6. Dark matter in spiral galaxies

    International Nuclear Information System (INIS)

    Persic, M.; Salucci, P.

    1990-01-01

    The Tully-Fisher relation is used to probe dark matter (DM) in the optical regions of spiral galaxies. By establishing it at several different isophotal radii in an appropriate sample of 58 galaxies with good B-band photometry and rotation curves, it is shown that some of its attributes (such as scatter, residuals, nonlinearity, and bias) dramatically decrease moving from the disk edge inward. This behavior challenges any mass model which assumes no DM or a luminosity-independent DM mass fraction interior to the optical radius of spiral galaxies. 58 refs

  7. Surface contact fatigue failures in gears

    CSIR Research Space (South Africa)

    Fernandes, PJL

    1997-06-01

    Full Text Available Surface contact fatigue is the most common cause of gear failure. It results in damage to contacting surfaces which can significantly reduce the load-carrying capacity of components, and may ultimately lead to complete failure of a gear. Three types...

  8. Shimmy of Aircraft Main Landing Gears

    NARCIS (Netherlands)

    Besselink, I.J.M.

    2000-01-01

    The landing gear is an important aircraft system, which has to meet many different design requirements. It is a highly loaded structure, which is designed for minimum weight. Shimmy is a dynamic instability of the landing gear, which is caused by the interaction of the dynamic behaviour of the

  9. Tooth bending fatigue failures in gears

    CSIR Research Space (South Africa)

    Fernandes, PJL

    1996-09-01

    Full Text Available . It results in progressive damage to gear teeth and ultimately leads to complete failure of the gear. The characteristics of this failure mode are discussed in detail and a number of actual case studies are presented which show the occurrence of this failure...

  10. A method for gear fatigue life prediction considering the internal flow field of the gear pump

    Science.gov (United States)

    Shen, Haidong; Li, Zhiqiang; Qi, Lele; Qiao, Liang

    2018-01-01

    Gear pump is the most widely used volume type hydraulic pump, and it is the main power source of the hydraulic system. Its performance is influenced by many factors, such as working environment, maintenance, fluid pressure and so on. It is different from the gear transmission system, the internal flow field of gear pump has a greater impact on the gear life, therefore it needs to consider the internal hydraulic system when predicting the gear fatigue life. In this paper, a certain aircraft gear pump as the research object, aim at the typical failure forms, gear contact fatigue, of gear pump, proposing the prediction method based on the virtual simulation. The method use CFD (Computational fluid dynamics) software to analyze pressure distribution of internal flow field of the gear pump, and constructed the unidirectional flow-solid coupling model of gear to acquire the contact stress of tooth surface on Ansys workbench software. Finally, employing nominal stress method and Miner cumulative damage theory to calculated the gear contact fatigue life based on modified material P-S-N curve. Engineering practice show that the method is feasible and efficient.

  11. Quasicrystallography on the spiral of Archimedes

    International Nuclear Information System (INIS)

    Bursill, L.A.

    1990-01-01

    The concept of a spiral lattice is discussed. Some examples of known mineral structures, namely clino asbestos, halloysite and cylindrite, are then interpreted in terms of this structural principle. An example of a synthetic sulphide catalyst spiral structure having atomic dimensions is also described. All of these inorganic spiral structures are based on the sprial of Archimedes. The principles for a new type of crystallography, based on the Archimedian spiral, are then presented. 45 refs., 8 figs

  12. A study of spiral galaxies

    International Nuclear Information System (INIS)

    Wevers, B.M.H.R.

    1984-01-01

    Attempts have been made to look for possible correlations between integral properties of spiral galaxies as a function of morphological type. To investigate this problem, one needs the detailed distribution of both the gaseous and the stellar components for a well-defined sample of spiral galaxies. A sample of about 20 spiral galaxies was therefore defined; these galaxies were observed in the 21 cm neutral hydrogen line with the Westerbork Synthesis Radio Telescope and in three broad-band optical colours with the 48-inch Palomar Smidt Telescope. First, an atlas of the combined radio and optical observations of 16 nearby northern-hemisphere spiral galaxies is presented. Luminosity profiles are discussed and the scale lengths of the exponential disks and extrapolated central surface brightnesses are derived, as well as radial color distributions; azimuthal surface brightness distributions and rotation curves. Possible correlations with optical features are investigated. It is found that 20 to 50 per cent of the total mass is in the disk. (Auth.)

  13. The Spiral Pattern During Development*

    African Journals Online (AJOL)

    1971-08-07

    Aug 7, 1971 ... which are destined to become the limb areas bud out laterally. Fig. 8. The early cells, which are destined to develop into the upper and the lower limbs, after lateral budding has occurred. Fig. 11 demonstrates the human embryo of about 5 mm. CR length and age of about 32 days. The spiral pattern is.

  14. TESTING THEORIES IN BARRED-SPIRAL GALAXIES

    International Nuclear Information System (INIS)

    Martínez-García, Eric E.

    2012-01-01

    According to one version of the recently proposed 'manifold' theory that explains the origin of spirals and rings in relation to chaotic orbits, galaxies with stronger bars should have a higher spiral arms pitch angle when compared to galaxies with weaker bars. A subsample of barred-spiral galaxies in the Ohio State University Bright Galaxy Survey was used to analyze the spiral arms pitch angle. These were compared with bar strengths taken from the literature. It was found that the galaxies in which the spiral arms maintain a logarithmic shape for more than 70° seem to corroborate the predicted trend.

  15. Comparative study of the endoscope-based bevelled and volume fiber-optic Raman probes for optical diagnosis of gastric dysplasia in vivo at endoscopy.

    Science.gov (United States)

    Wang, Jianfeng; Lin, Kan; Zheng, Wei; Ho, Khek Yu; Teh, Ming; Yeoh, Khay Guan; Huang, Zhiwei

    2015-11-01

    This study aims to compare the diagnostic performance of the two different endoscope-based fiber-optic Raman probe designs (i.e., bevelled and volume Raman probes) for real-time, in vivo detection of gastric dysplasia at endoscopy. To conduct the clinical comparison, a total of 1,050 in vivo tissue Raman spectra (normal: n = 864; dysplasia: n = 186) were acquired from 66 gastric patients (normal: n = 48; dysplasia: n = 18) by using bevelled Raman probe, while a total of 1,913 in vivo tissue Raman spectra (normal: n = 1,786; dysplasia: n = 127) were acquired from 98 gastric patients (normal: n = 87; dysplasia: n = 11) by using volume Raman probe. The bevelled Raman probe provides approximately twofold improvements in tissue Raman-to-autofluorescence intensity ratios as compared to the use of volume Raman probe. Partial least squares discriminant analysis together with leave-one patient-out cross-validation on in vivo tissue Raman spectra acquired yields a diagnostic accuracy of 93.0 % (sensitivity of 92.5 %; specificity of 93.1 %) for differentiating gastric dysplasia from normal gastric tissue by using the bevelled fiber-optic Raman probe, which is superior to the diagnostic performance (accuracy of 88.4 %; sensitivity of 85.8 %; specificity of 88.6 %) by using the volume Raman probe. This work demonstrates that the Raman spectroscopic technique coupled with bevelled fiber-optic Raman probe has great potential to enhance in vivo diagnosis of gastric precancer and early cancer at endoscopy. Graphical Abstract Comparison of in vivo gastric tissue Raman spectra acquired by using bevelled and volume fiber-optic Raman probes.

  16. Interaction of multiarmed spirals in bistable media.

    Science.gov (United States)

    He, Ya-feng; Ai, Bao-quan; Liu, Fu-cheng

    2013-05-01

    We study the interaction of both dense and sparse multiarmed spirals in bistable media modeled by equations of the FitzHugh-Nagumo type. A dense one-armed spiral is characterized by its fixed tip. For dense multiarmed spirals, when the initial distance between tips is less than a critical value, the arms collide, connect, and disconnect continuously as the spirals rotate. The continuous reconstruction between the front and the back drives the tips to corotate along a rough circle and to meander zigzaggedly. The rotation frequency of tip, the frequency of zigzagged displacement, the frequency of spiral, the oscillation frequency of media, and the number of arms satisfy certain relations as long as the control parameters of the model are fixed. When the initial distance between tips is larger than the critical value, the behaviors of individual arms within either dense or sparse multiarmed spirals are identical to that of corresponding one-armed spirals.

  17. Engagement of Metal Debris into Gear Mesh

    Science.gov (United States)

    handschuh, Robert F.; Krantz, Timothy L.

    2010-01-01

    A series of bench-top experiments was conducted to determine the effects of metallic debris being dragged through meshing gear teeth. A test rig that is typically used to conduct contact fatigue experiments was used for these tests. Several sizes of drill material, shim stock and pieces of gear teeth were introduced and then driven through the meshing region. The level of torque required to drive the "chip" through the gear mesh was measured. From the data gathered, chip size sufficient to jam the mechanism can be determined.

  18. 50 CFR 622.46 - Prevention of gear conflicts.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Prevention of gear conflicts. 622.46... Management Measures § 622.46 Prevention of gear conflicts. (a) No person may knowingly place in the Gulf EEZ any article, including fishing gear, that interferes with fishing or obstructs or damages fishing gear...

  19. 46 CFR 108.641 - Instructions for changing steering gear.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Instructions for changing steering gear. 108.641 Section... steering gear. Instructions stating, in order, the different steps to be taken for changing to emergency and secondary steering gear must be posted in the steering gear room and at each secondary steering...

  20. 14 CFR 25.1515 - Landing gear speeds.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Landing gear speeds. 25.1515 Section 25... Limitations § 25.1515 Landing gear speeds. (a) The established landing gear operating speed or speeds, V LO, may not exceed the speed at which it is safe both to extend and to retract the landing gear, as...

  1. 50 CFR 654.25 - Prevention of gear conflicts.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Prevention of gear conflicts. 654.25... Measures § 654.25 Prevention of gear conflicts. (a) No person may knowingly place in the management area any article, including fishing gear, that interferes with fishing or obstructs or damages fishing gear...

  2. 49 CFR 230.77 - Foundation brake gear.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Foundation brake gear. 230.77 Section 230.77... Tenders Brake and Signal Equipment § 230.77 Foundation brake gear. (a) Maintenance. Foundation brake gear...) Distance above the rails. No part of the foundation brake gear of the steam locomotive or tender shall be...

  3. 50 CFR 640.22 - Gear and diving restrictions.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Gear and diving restrictions. 640.22... ATLANTIC Management Measures § 640.22 Gear and diving restrictions. (a) Prohibited gear and methods. (1) A spiny lobster may not be taken in the EEZ with a spear, hook, or similar device, or gear containing such...

  4. 29 CFR 1919.31 - Proof tests-loose gear.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Proof tests-loose gear. 1919.31 Section 1919.31 Labor... (CONTINUED) GEAR CERTIFICATION Certification of Vessels: Tests and Proof Loads; Heat Treatment; Competent Persons § 1919.31 Proof tests—loose gear. (a) Chains, rings, shackles and other loose gear (whether...

  5. 46 CFR 58.25-20 - Piping for steering gear.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Piping for steering gear. 58.25-20 Section 58.25-20... MACHINERY AND RELATED SYSTEMS Steering Gear § 58.25-20 Piping for steering gear. (a) Pressure piping must... the hydraulic system can be readily recharged from within the steering-gear compartment and must be...

  6. DESIGN FOR A BI-PLANETARY GEAR TRAIN

    Directory of Open Access Journals (Sweden)

    Józef DREWNIAK

    2016-06-01

    Full Text Available The article presents the design for a bi-planetary gear train. The project description is supplemented with calculations of kinematics, statics and meshing efficiency of the gear wheels included in the gear train. Excluded are calculations of strength and geometry of gears, shaft and rolling bearing, since they are similar to classical calculations for planetary gears. An assembly drawing in 2D and assembly drawings in 3D of the designed bi-planetary gear train are also shown. This gear train will form the main element of the research in hand.

  7. 50 CFR 654.22 - Gear restrictions.

    Science.gov (United States)

    2010-10-01

    ..., DEPARTMENT OF COMMERCE STONE CRAB FISHERY OF THE GULF OF MEXICO Management Measures § 654.22 Gear... retaining chamber. (6) A plastic or wire trap must have a degradable panel. (i) A plastic trap will be...

  8. Sea Turtle Human/Gear Interactions Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Southeast Fisheries Science Center Mississippi Laboratories is responsible for new gear development and testing to reduce bycatch and incidental interactions of...

  9. Gulf of Mexico Shrimp Permit Gear Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data set contains annual vessel gear characterization of permit holders shrimp vessel. Data includes net type, TED type, BRD type, etc.

  10. 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

  11. Tooth contact analysis of spur gears. Part 2-Analysis of modified gears

    Directory of Open Access Journals (Sweden)

    Pop Nicolae

    2017-01-01

    Full Text Available The misalignment between gears axes or direction deviations of teeth leads accentuate the edge effect, Modified spur gears which localize the initial bearing contact by proper modifications of the lead profile are used to avoid the development of the edge effect. A semi-analytical method was involved to find the contact area, pressures distribution and depth stresses states for the standard gears and gears with modified lead profile. The lead modifications concerned the crowning of the flank surface and the end relieving of the tooth flanks, both being applied to the pinion teeth only.

  12. Low-pressure CVD-grown β-Ga2O3 bevel-field-plated Schottky barrier diodes

    Science.gov (United States)

    Joishi, Chandan; Rafique, Subrina; Xia, Zhanbo; Han, Lu; Krishnamoorthy, Sriram; Zhang, Yuewei; Lodha, Saurabh; Zhao, Hongping; Rajan, Siddharth

    2018-03-01

    We report (010)-oriented β-Ga2O3 bevel-field-plated mesa Schottky barrier diodes grown by low-pressure chemical vapor deposition (LPCVD) using a solid Ga precursor and O2 and SiCl4 sources. Schottky diodes with good ideality and low reverse leakage were realized on the epitaxial material. Edge termination using beveled field plates yielded a breakdown voltage of -190 V, and maximum vertical electric fields of 4.2 MV/cm in the center and 5.9 MV/cm at the edge were estimated, with extrinsic R ON of 3.9 mΩ·cm2 and extracted intrinsic R ON of 0.023 mΩ·cm2. The reported results demonstrate the high quality of homoepitaxial LPCVD-grown β-Ga2O3 thin films for vertical power electronics applications, and show that this growth method is promising for future β-Ga2O3 technology.

  13. High Speed Gear Sized and Configured to Reduce Windage Loss

    Science.gov (United States)

    Kunz, Robert F. (Inventor); Medvitz, Richard B. (Inventor); Hill, Matthew John (Inventor)

    2013-01-01

    A gear and drive system utilizing the gear include teeth. Each of the teeth has a first side and a second side opposite the first side that extends from a body of the gear. For each tooth of the gear, a first extended portion is attached to the first side of the tooth to divert flow of fluid adjacent to the body of the gear to reduce windage losses that occur when the gear rotates. The gear may be utilized in drive systems that may have high rotational speeds, such as speeds where the tip velocities are greater than or equal to about 68 m/s. Some embodiments of the gear may also utilize teeth that also have second extended portions attached to the second sides of the teeth to divert flow of fluid adjacent to the body of the gear to reduce windage losses that occur when the gear rotates.

  14. Low surface brightness spiral galaxies

    International Nuclear Information System (INIS)

    Romanishin, W.

    1980-01-01

    This dissertation presents an observational overview of a sample of low surface brightness (LSB) spiral galaxies. The sample galaxies were chosen to have low surface brightness disks and indications of spiral structure visible on the Palomar Sky Survey. They are of sufficient angular size (diameter > 2.5 arcmin), to allow detailed surface photometry using Mayall 4-m prime focus plates. The major findings of this dissertation are: (1) The average disk central surface brightness of the LSB galaxies is 22.88 magnitude/arcsec 2 in the B passband. (2) From broadband color measurements of the old stellar population, we infer a low average stellar metallicity, on the order of 1/5 solar. (3) The spectra and optical colors of the HII regions in the LSB galaxies indicate a lack of hot ionizing stars compared to HII regions in other late-type galaxies. (4) The average surface mass density, measured within the radius containing half the total mass, is less than half that of a sample of normal late-type spirals. (5) The average LSB galaxy neutral hydrogen mass to blue luminosity ratio is about 0.6, significantly higher than in a sample of normal late-type galaxies. (6) We find no conclusive evidence of an abnormal mass-to-light ratio in the LSB galaxies. (7) Some of the LSB galaxies exhibit well-developed density wave patterns. (8) A very crude calculation shows the lower metallicity of the LSB galaxies compared with normal late-type spirals might be explained simply by the deficiency of massive stars in the LSB galaxies

  15. Dynamical models of spiral galaxies

    International Nuclear Information System (INIS)

    Grosbol, P.

    1990-01-01

    The effects of changing the basic parameters of rotation curve steepness, amount of bulge, and pitch angle of the imposed spiral pattern in the galactic model of Contoupolos and Grosbel (1986) are investigated. The general conclusions of the model are confirmed and shown to be insensitive to the specific choice of parameters for the galactic potential. The exact amplitude at which the nonlinear effects at the 4:1 resonance become important do, however, depend on the model

  16. Multiple mechanisms quench passive spiral galaxies

    Science.gov (United States)

    Fraser-McKelvie, Amelia; Brown, Michael J. I.; Pimbblet, Kevin; Dolley, Tim; Bonne, Nicolas J.

    2018-02-01

    We examine the properties of a sample of 35 nearby passive spiral galaxies in order to determine their dominant quenching mechanism(s). All five low-mass (M⋆ environments. We postulate that cluster-scale gas stripping and heating mechanisms operating only in rich clusters are required to quench low-mass passive spirals, and ram-pressure stripping and strangulation are obvious candidates. For higher mass passive spirals, while trends are present, the story is less clear. The passive spiral bar fraction is high: 74 ± 15 per cent, compared with 36 ± 5 per cent for a mass, redshift and T-type matched comparison sample of star-forming spiral galaxies. The high mass passive spirals occur mostly, but not exclusively, in groups, and can be central or satellite galaxies. The passive spiral group fraction of 74 ± 15 per cent is similar to that of the comparison sample of star-forming galaxies at 61 ± 7 per cent. We find evidence for both quenching via internal structure and environment in our passive spiral sample, though some galaxies have evidence of neither. From this, we conclude no one mechanism is responsible for quenching star formation in passive spiral galaxies - rather, a mixture of mechanisms is required to produce the passive spiral distribution we see today.

  17. Instrumentation and test gear circuits manual

    CERN Document Server

    Marston, R M

    2013-01-01

    Instrumentation and Test Gear Circuits Manual provides diagrams, graphs, tables, and discussions of several types of practical circuits. The practical circuits covered in this book include attenuators, bridges, scope trace doublers, timebases, and digital frequency meters. Chapter 1 discusses the basic instrumentation and test gear principles. Chapter 2 deals with the design of passive attenuators, and Chapter 3 with passive and active filter circuits. The subsequent chapters tackle 'bridge' circuits, analogue and digital metering techniques and circuitry, signal and waveform generation, and p

  18. Ultrasonic test of highly stressed gear shafts

    Energy Technology Data Exchange (ETDEWEB)

    Schreiner, T. [Siemens AG, Power Generation, KWU, Muelheim (Germany); Heinrich, W. [Siemens AG, Power Generation, KWU, Berlin (Germany); Achtzehn, J. [Siemens AG, Power Generation, ICVW, Erlangen (Germany); Hensley, H. [Siemens Power Generation (Germany)

    1998-12-31

    In the power plant industry, gears are used for increasingly higher turbine capacities. Efficiency enhancements, particularly for the combined gas and steam turbine process, lead to an increase in stresses, even for high-performance gears. Consequently, the requirements for non-destructive material testing are on the increase as well. At Siemens KWU, high-performance gears are used so far only for gas turbines with lower rating (65 MW) to adapt the gas turbine speed (5413 rpm) to the generator speed (3000 rpm/ 50 Hz or 3600 rpm/60 Hz). The gear train consists of a forged and case-hardened wheel shaft and pinion shaft made of material 17 CrNiMo 6, where the wheel shaft can be either a solid or a hollow shaft. Dimensions are typically 2.3 m length and 1 m diameter. As a rule, pinion shafts are solid. The gear design, calling for an additional torsion shaft turning inside the hollow wheel shaft, can absorb more torsional load surges and is more tolerant of deviations during gear train alignment. This design requires two additional forgings (torsion shaft and hub) and an additional bearing 2 refs.

  19. Ultrasonic test of highly stressed gear shafts

    Energy Technology Data Exchange (ETDEWEB)

    Schreiner, T [Siemens AG, Power Generation, KWU, Muelheim (Germany); Heinrich, W [Siemens AG, Power Generation, KWU, Berlin (Germany); Achtzehn, J [Siemens AG, Power Generation, ICVW, Erlangen (Germany); Hensley, H [Siemens Power Generation (Germany)

    1999-12-31

    In the power plant industry, gears are used for increasingly higher turbine capacities. Efficiency enhancements, particularly for the combined gas and steam turbine process, lead to an increase in stresses, even for high-performance gears. Consequently, the requirements for non-destructive material testing are on the increase as well. At Siemens KWU, high-performance gears are used so far only for gas turbines with lower rating (65 MW) to adapt the gas turbine speed (5413 rpm) to the generator speed (3000 rpm/ 50 Hz or 3600 rpm/60 Hz). The gear train consists of a forged and case-hardened wheel shaft and pinion shaft made of material 17 CrNiMo 6, where the wheel shaft can be either a solid or a hollow shaft. Dimensions are typically 2.3 m length and 1 m diameter. As a rule, pinion shafts are solid. The gear design, calling for an additional torsion shaft turning inside the hollow wheel shaft, can absorb more torsional load surges and is more tolerant of deviations during gear train alignment. This design requires two additional forgings (torsion shaft and hub) and an additional bearing 2 refs.

  20. Systems and Methods for Implementing Bulk Metallic Glass-Based Strain Wave Gears and Strain Wave Gear Components

    Science.gov (United States)

    Hofmann, Douglas C. (Inventor); Wilcox, Brian (Inventor)

    2016-01-01

    Bulk metallic glass-based strain wave gears and strain wave gear components. In one embodiment, a strain wave gear includes: a wave generator; a flexspline that itself includes a first set of gear teeth; and a circular spline that itself includes a second set of gear teeth; where at least one of the wave generator, the flexspline, and the circular spline, includes a bulk metallic glass-based material.

  1. Collective excitations in itinerant spiral magnets

    International Nuclear Information System (INIS)

    Kampf, A.P.

    1996-01-01

    We investigate the coupled charge and spin collective excitations in the spiral phases of the two-dimensional Hubbard model using a generalized random-phase approximation. Already for small doping the spin-wave excitations are strongly renormalized due to low-energy particle-hole excitations. Besides the three Goldstone modes of the spiral state the dynamical susceptibility reveals an extra zero mode for low doping and strong coupling values signaling an intrinsic instability of the homogeneous spiral state. In addition, near-zero modes are found in the vicinity of the spiral pitch wave number for out-of-plane spin fluctuations. Their origin is found to be the near degeneracy with staggered noncoplanar spiral states which, however, are not the lowest energy Hartree-Fock solutions among the homogeneous spiral states. copyright 1996 The American Physical Society

  2. 78 FR 68817 - Proposed Information Collection; Comment Request; Northeast Region Gear Identification

    Science.gov (United States)

    2013-11-15

    ... gear type being used to help prevent gear conflicts. II. Method of Collection No information is... certain types of fishing gear mark the gear with specified information. The gear marking requirements... for marking several strings of a given gear type, or may use multiple different gear types that...

  3. Gear Tooth Root Stresses of a Very Heavily Loaded Gear Pair-Case Study: Orbiter Body Flap Actuator Pinion and Ring Gear

    Science.gov (United States)

    Krantz, Timothy L.; Handschuh, Robert F.

    2015-01-01

    The space shuttle orbiter's body flap actuator gearing was assessed as a case study of the stresses for very heavily loaded external-internal gear pairs (meshing pinion and ring gear). For many applications, using the high point of single tooth contact (HPSTC) to locate the position of the tooth force is adequate for assessing the maximum tooth root stress condition. But for aerospace gearing such an approach may be inadequate for assessing the stress condition while also simultaneously minimizing mass. In this work specialized contact analyses and finite element methods were used to study gear tooth stresses of body flap actuator gears. The analytical solutions considered the elastic deformations as an inherent part of the solutions. The ratio for the maximum tooth stresses using the HPSTC approach solutions relative to the contact analysis and finite element solutions were 1.40 for the ring gear and 1.28 for the pinion gear.

  4. Research on the Problem of Spur Gear Teeth Contact in the Car Gear Box

    Directory of Open Access Journals (Sweden)

    Viktor Skrickij

    2011-04-01

    Full Text Available The article presents research on the problem of two gear contact in the car gearbox. Contact stiffness is evaluated for the whole period of mesh. Also, contact stresses are evaluated in the contact place. The presented method can be used for calculating spur gear.Article in Lithuanian

  5. Solvable model of spiral wave chimeras.

    Science.gov (United States)

    Martens, Erik A; Laing, Carlo R; Strogatz, Steven H

    2010-01-29

    Spiral waves are ubiquitous in two-dimensional systems of chemical or biological oscillators coupled locally by diffusion. At the center of such spirals is a phase singularity, a topological defect where the oscillator amplitude drops to zero. But if the coupling is nonlocal, a new kind of spiral can occur, with a circular core consisting of desynchronized oscillators running at full amplitude. Here, we provide the first analytical description of such a spiral wave chimera and use perturbation theory to calculate its rotation speed and the size of its incoherent core.

  6. Evolutionary Acquisition and Spiral Development Tutorial

    National Research Council Canada - National Science Library

    Hantos, P

    2005-01-01

    .... NSS Acquisition Policy 03-01 provided some space-oriented customization and, similarly to the original DOD directives, also positioned Evolutionary Acquisition and Spiral Development as preferred...

  7. Solvable Model of Spiral Wave Chimeras

    DEFF Research Database (Denmark)

    Martens, Erik Andreas; Laing, Carlo R.; Strogatz, Steven H.

    2010-01-01

    Spiral waves are ubiquitous in two-dimensional systems of chemical or biological oscillators coupled locally by diffusion. At the center of such spirals is a phase singularity, a topological defect where the oscillator amplitude drops to zero. But if the coupling is nonlocal, a new kind of spiral...... can occur, with a circular core consisting of desynchronized oscillators running at full amplitude. Here, we provide the first analytical description of such a spiral wave chimera and use perturbation theory to calculate its rotation speed and the size of its incoherent core....

  8. Application of Face-Gear Drives in Helicopter Transmissions

    Science.gov (United States)

    Litvin, F. L.; Wang, J.-C.; Bossler, R. B., Jr.; Chen, Y.-J. D.; Heath, G.; Lewicki, D. G.

    1992-01-01

    The use of face gears in helicopter transmissions was explored. A light-weight, split torque transmission design utilizing face gears was described. Face-gear design and geometry were investigated. Topics included tooth generation, limiting inner and outer radii, tooth contact analysis, contact ratio, gear eccentricity, and structural stiffness. Design charts were developed to determine minimum and maximum face-gear inner and outer radii. Analytical study of transmission error showed face-gear drives were relatively insensitive to gear misalignment, but tooth contact was affected by misalignment. A method of localizing bearing contact to compensate for misalignment was explored. The proper choice of shaft support stiffness enabled good load sharing in the split torque transmission design. Face-gear experimental studies were also included and the feasibility of face gears in high-speed, high-load applications such as helicopter transmissions was demonstrated.

  9. Spiral 2 the scientific objectives

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-06-15

    The French ministry of research took the decision to build Spiral-2 in May 2005. Its construction costs are estimated to 130 million euros while its operating costs will near 8.5 million euros per year. The construction works will last 5 years. The Spiral-2 facility is based on a high power, superconducting driver Linac, which will deliver a high intensity, 40 MeV deuteron beam as well as a variety of heavy-ion beams with mass over charge ratio equal to 3 and energy up to 14.5 MeV/nucleon. Using a carbon converter, fast neutrons from the breakup of the 5 mA of deuterons impinging on a uranium carbide target will induce a rate of up to 10{sup 14} fissions/s. The radioactive ion beam intensities in the mass range from A = 60 to 140 will be of the order of 10{sup 6} to 10{sup 11} particles/s surpassing by one or two orders-of-magnitude any existing facility in the world. A direct irradiation of the UC{sub 2} target with {sup 3,4}He, {sup 6,7}Li or {sup 12}C may also be used. Different production targets will be used to produce high-intensity beams of light radioactive species with the Isol technique. The extracted radioactive ion beam will be accelerated to energies up to 20 MeV/nucleons by the existing Cime cyclotron. One of the most important features of the future Ganil accelerator complex will be the capability of delivering up to 5 stable or radioactive beams simultaneously in the energy range from the keV to several tens of MeV/nucleons. The document details also the future contribution of Spiral-2 concerning the structure of exotic nuclei, the thermodynamical aspects of nuclear matter, nucleosynthesis, the fundamental basic interactions, and the use of neutrons. (A.C.)

  10. Spiral 2 the scientific objectives

    International Nuclear Information System (INIS)

    2006-06-01

    The French ministry of research took the decision to build Spiral-2 in May 2005. Its construction costs are estimated to 130 million euros while its operating costs will near 8.5 million euros per year. The construction works will last 5 years. The Spiral-2 facility is based on a high power, superconducting driver Linac, which will deliver a high intensity, 40 MeV deuteron beam as well as a variety of heavy-ion beams with mass over charge ratio equal to 3 and energy up to 14.5 MeV/nucleon. Using a carbon converter, fast neutrons from the breakup of the 5 mA of deuterons impinging on a uranium carbide target will induce a rate of up to 10 14 fissions/s. The radioactive ion beam intensities in the mass range from A = 60 to 140 will be of the order of 10 6 to 10 11 particles/s surpassing by one or two orders-of-magnitude any existing facility in the world. A direct irradiation of the UC 2 target with 3,4 He, 6,7 Li or 12 C may also be used. Different production targets will be used to produce high-intensity beams of light radioactive species with the Isol technique. The extracted radioactive ion beam will be accelerated to energies up to 20 MeV/nucleons by the existing Cime cyclotron. One of the most important features of the future Ganil accelerator complex will be the capability of delivering up to 5 stable or radioactive beams simultaneously in the energy range from the keV to several tens of MeV/nucleons. The document details also the future contribution of Spiral-2 concerning the structure of exotic nuclei, the thermodynamical aspects of nuclear matter, nucleosynthesis, the fundamental basic interactions, and the use of neutrons. (A.C.)

  11. The rotation of spiral galaxies.

    Science.gov (United States)

    Rubin, V C

    1983-06-24

    There is accumulating evidence that as much as 90 percent of the mass of the universe is nonluminous and is clumped, halo-like, around individual galaxies. The gravitational force of this dark matter is presumed to be responsible for the high rotational velocities of stars and gas in the disks of spiral galaxie. At present, the form of the dark matter is unknown. Possible candidates span a range in mass of 10(70), from non-zero-mass neutrinos to massive black holes.

  12. A Computational Investigation of Gear Windage

    Science.gov (United States)

    Hill, Matthew J.; Kunz, Robert F.

    2012-01-01

    A CFD method has been developed for application to gear windage aerodynamics. The goals of this research are to develop and validate numerical and modeling approaches for these systems, to develop physical understanding of the aerodynamics of gear windage loss, including the physics of loss mitigation strategies, and to propose and evaluate new approaches for minimizing loss. Absolute and relative frame CFD simulation, overset gridding, multiphase flow analysis, and sub-layer resolved turbulence modeling were brought to bear in achieving these goals. Several spur gear geometries were studied for which experimental data are available. Various shrouding configurations and free-spinning (no shroud) cases were studied. Comparisons are made with experimental data from the open literature, and data recently obtained in the NASA Glenn Research Center Gear Windage Test Facility. The results show good agreement with experiment. Interrogation of the validative and exploratory CFD results have led, for the first time, to a detailed understanding of the physical mechanisms of gear windage loss, and have led to newly proposed mitigation strategies whose effectiveness is computationally explored.

  13. D Modelling with the Samsung Gear 360

    Science.gov (United States)

    Barazzetti, L.; Previtali, M.; Roncoroni, F.

    2017-02-01

    The Samsung Gear 360 is a consumer grade spherical camera able to capture photos and videos. The aim of this work is to test the metric accuracy and the level of detail achievable with the Samsung Gear 360 coupled with digital modelling techniques based on photogrammetry/computer vision algorithms. Results demonstrate that the direct use of the projection generated inside the mobile phone or with Gear 360 Action Direction (the desktop software for post-processing) have a relatively low metric accuracy. As results were in contrast with the accuracy achieved by using the original fisheye images (front and rear facing images) in photogrammetric reconstructions, an alternative solution to generate the equirectangular projections was developed. A calibration aimed at understanding the intrinsic parameters of the two lenses camera, as well as their relative orientation, allowed one to generate new equirectangular projections from which a significant improvement of geometric accuracy has been achieved.

  14. MODELING THE DOUBLE WORM-FACE GEARS

    Directory of Open Access Journals (Sweden)

    BOLOŞ Codruţa

    2015-06-01

    Full Text Available The worm-face gear family, invented 60 years ago, contains in its structure several variants which have the following defining elements: tapered worm, reverse tapered worm and cylindrical worm. This type of gear can be realized with a single wheel and also in engagement with the second embodiment of the front worm wheels. This paper presents the matrix - vectorial mathematical model of the double worm-face gear with cylindrical worm and a graphical modeling which is based on the specific geometrical characteristics accomplished by means of the Autodesk Inventor 3D modeling program. The applicability of the study, considering the solutions which it suggests, aims to create opportunities for the use of modern rapid prototyping and analysis of stress FEM technique.

  15. Spiral density waves in M81. I. Stellar spiral density waves

    International Nuclear Information System (INIS)

    Feng, Chien-Chang; Lin, Lien-Hsuan; Wang, Hsiang-Hsu; Taam, Ronald E.

    2014-01-01

    Aside from the grand-design stellar spirals appearing in the disk of M81, a pair of stellar spiral arms situated well inside the bright bulge of M81 has been recently discovered by Kendall et al. The seemingly unrelated pairs of spirals pose a challenge to the theory of spiral density waves. To address this problem, we have constructed a three-component model for M81, including the contributions from a stellar disk, a bulge, and a dark matter halo subject to observational constraints. Given this basic state for M81, a modal approach is applied to search for the discrete unstable spiral modes that may provide an understanding for the existence of both spiral arms. It is found that the apparently separated inner and outer spirals can be interpreted as a single trailing spiral mode. In particular, these spirals share the same pattern speed 25.5 km s –1 kpc –1 with a corotation radius of 9.03 kpc. In addition to the good agreement between the calculated and the observed spiral pattern, the variation of the spiral amplitude can also be naturally reproduced.

  16. QS Spiral: Visualizing Periodic Quantified Self Data

    DEFF Research Database (Denmark)

    Larsen, Jakob Eg; Cuttone, Andrea; Jørgensen, Sune Lehmann

    2013-01-01

    In this paper we propose an interactive visualization technique QS Spiral that aims to capture the periodic properties of quantified self data and let the user explore those recurring patterns. The approach is based on time-series data visualized as a spiral structure. The interactivity includes ...

  17. 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

  18. Spiral groove seal. [for rotating shaft

    Science.gov (United States)

    Ludwig, L. P.; Strom, T. N. (Inventor)

    1974-01-01

    Mating flat surfaces inhibit leakage of a fluid around a stationary shaft. A spiral groove produces a pumping action toward the fluid when the shaft rotates. This prevents leakage while a generated hydraulic lifting force separates the mating surfaces to minimize wear. Provision is made for placing these spiral grooves in communication with the fluid to accelerate the generation of the hydraulic lifting force.

  19. ANGULAR-MOMENTUM IN BINARY SPIRAL GALAXIES

    NARCIS (Netherlands)

    OOSTERLOO, T

    In order to investigate the relative orientations of spiral galaxies in pairs, the distribution of the angle between the spin-vectors for a new sample of 40 binary spiral galaxies is determined. From this distribution it is found, contrary to an earlier result obtained by Helou (1984), that there is

  20. Colours and morphology of spiral galaxies

    International Nuclear Information System (INIS)

    Wyse, R.F.G.

    1981-01-01

    Tinsley has proposed that late-type spirals have relatively more non-luminous material than early-type spirals. A re-examination of the data indicates that this proposal is equally consistent with dark matter being more dominant in barred galaxies than in unbarred galaxies. Neither conclusion can be firm, since the dataset is far from ideal. (author)

  1. Scaling effects in spiral capsule robots.

    Science.gov (United States)

    Liang, Liang; Hu, Rong; Chen, Bai; Tang, Yong; Xu, Yan

    2017-04-01

    Spiral capsule robots can be applied to human gastrointestinal tracts and blood vessels. Because of significant variations in the sizes of the inner diameters of the intestines as well as blood vessels, this research has been unable to meet the requirements for medical applications. By applying the fluid dynamic equations, using the computational fluid dynamics method, to a robot axial length ranging from 10 -5 to 10 -2  m, the operational performance indicators (axial driving force, load torque, and maximum fluid pressure on the pipe wall) of the spiral capsule robot and the fluid turbulent intensity around the robot spiral surfaces was numerically calculated in a straight rigid pipe filled with fluid. The reasonableness and validity of the calculation method adopted in this study were verified by the consistency of the calculated values by the computational fluid dynamics method and the experimental values from a relevant literature. The results show that the greater the fluid turbulent intensity, the greater the impact of the fluid turbulence on the driving performance of the spiral capsule robot and the higher the energy consumption of the robot. For the same level of size of the robot, the axial driving force, the load torque, and the maximum fluid pressure on the pipe wall of the outer spiral robot were larger than those of the inner spiral robot. For different requirements of the operating environment, we can choose a certain kind of spiral capsule robot. This study provides a theoretical foundation for spiral capsule robots.

  2. Improved reconstruction for IDEAL spiral CSI

    DEFF Research Database (Denmark)

    Hansen, Rie Beck; Mariager, Christian; Laustsen, Christoffer

    2017-01-01

    In this study we demonstrate how reconstruction for IDEAL spiral CSI (spectroscopic imaging scheme developed for hyperpolarized dynamic metabolic MR imaging) can be improved by using regularization with a sparsity constraint. By exploiting sparsity of the spectral domain, IDEAL spiral CSI can...

  3. Effect of tooth profile modification on wear in internal gears

    Science.gov (United States)

    Tunalioglu, M. S.; Tuc, B.

    2018-05-01

    Internal gears are often used in the automotive industry when two gears are required to rotate in the same direction. Tooth shapes, slippage speeds at the beginning and end of meshing are different according to the external gears. Manufacturing of internal gears is more difficult than external gears. Thus, it is necessary to determine the working conditions and wear behavior of internal gears carefully. The profile modification method in terms of strength and surface tension of the gear mechanism are performed in order to increase the load-carrying capability. In this study, profile modification method was performed in the internal gears to reduce the wear on the teeth. For this purpose, the wear of the internal gears was theoretically investigated by adapting the Archard wear equation to the internal gears. Closed circuit power circulation system was designed and manufactured to experimentally investigate the wear in internal gears. With this system, wear tests of gears made of St 50 material without profile modification and different profile modifications were made and the results were compared. Experimental study was performed in the same loading and cycle time conditions to validate the theoretical results and it was seen that the results are compatible. According to the experimental results, it is seen that in the internal gears, when profile modification done the wear is decreased in the teeth tip region.

  4. Shuttle Rudder/Speed Brake Power Drive Unit (PDU) Gear Scuffing Tests With Flight Gears

    Science.gov (United States)

    Proctor, Margaret P.; Oswald, Fred B.; Krants, Timothy L.

    2005-01-01

    Scuffing-like damage has been found on the tooth surfaces of gears 5 and 6 of the NASA space shuttle rudder/speed brake power drive unit (PDU) number 2 after the occurrence of a transient back-driving event in flight. Tests were conducted using a pair of unused spare flight gears in a bench test at operating conditions up to 2866 rpm and 1144 in.-lb at the input ring gear and 14,000 rpm and 234 in.-lb at the output pinion gear, corresponding to a power level of 52 hp. This test condition exceeds the maximum estimated conditions expected in a backdriving event thought to produce the scuffing damage. Some wear marks were produced, but they were much less severe than the scuffing damaged produced during shuttle flight. Failure to produce scuff damage like that found on the shuttle may be due to geometrical variations between the scuffed gears and the gears tested herein, more severe operating conditions during the flight that produced the scuff than estimated, the order of the test procedures, the use of new hydraulic oil, differences between the dynamic response of the flight gearbox and the bench-test gearbox, or a combination of these. This report documents the test gears, apparatus, and procedures, summarizes the test results, and includes a discussion of the findings, conclusions, and recommendations.

  5. Comparison of an Inductance In-Line Oil Debris Sensor and Magnetic Plug Oil Debris Sensor

    Science.gov (United States)

    Dempsey, Paula J.; Tuck, Roger; Showalter, Stephen

    2012-01-01

    The objective of this research was to compare the performance of an inductance in-line oil debris sensor and magnetic plug oil debris sensor when detecting transmission component health in the same system under the same operating conditions. Both sensors were installed in series in the NASA Glenn Spiral Bevel Gear Fatigue Rig during tests performed on 5 gear sets (pinion/gear) when different levels of damage occurred on the gear teeth. Results of this analysis found both the inductance in-line oil debris sensor and magnetic plug oil debris sensor have benefits and limitations when detecting gearbox component damage.

  6. Vibration behavior optimization of planetary gear sets

    Directory of Open Access Journals (Sweden)

    Farshad Shakeri Aski

    2014-12-01

    Full Text Available This paper presents a global optimization method focused on planetary gear vibration reduction by means of tip relief profile modifications. A nonlinear dynamic model is used to study the vibration behavior. In order to investigate the optimal radius and amplitude, Brute Force method optimization is used. One approach in optimization is straightforward and requires considerable computation power: brute force methods try to calculate all possible solutions and decide afterwards which one is the best. Results show the influence of optimal profile on planetary gear vibrations.

  7. Power Consumption Optimization in Tooth Gears Processing

    Science.gov (United States)

    Kanatnikov, N.; Harlamov, G.; Kanatnikova, P.; Pashmentova, A.

    2018-01-01

    The paper reviews the issue of optimization of technological process of tooth gears production of the power consumption criteria. The authors dwell on the indices used for cutting process estimation by the consumed energy criteria and their applicability in the analysis of the toothed wheel production process. The inventors proposed a method for optimization of power consumptions based on the spatial modeling of cutting pattern. The article is aimed at solving the problem of effective source management in order to achieve economical and ecological effect during the mechanical processing of toothed gears. The research was supported by Russian Science Foundation (project No. 17-79-10316).

  8. Improving bending stress in spur gears using asymmetric gears and shape optimization

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard

    2010-01-01

    Bending stress plays a significant role in gear design wherein its magnitude is controlled by the nominal bending stress and the stress concentration due to the geometrical shape. The bending stress is indirectly related to shape changes made to the cutting tool. This work shows that the bending...... stress can be reduced significantly by using asymmetric gear teeth and by shape optimizing the gear through changes made to the tool geometry. However, to obtain the largest possible stress reduction a custom tool must be designed depending on the number of teeth, but the stress reductions found...

  9. Tooth contact analysis of spur gears. Part 1-SAM analysis of standard gears

    Directory of Open Access Journals (Sweden)

    Creţu Spiridon

    2017-01-01

    Full Text Available The involute gears are sensitive to the misalignment of their axes which determines transmission errors and perturbations of pressures distributions along the tooth flank. The concentrated contacts in gears are no longer as Hertz type. A semi-analytical method was developed to find the contact area, pressures distribution and depth stresses state. The matrix of initial separations is found analytically for standard and non-standard spur gears. The presence of misalignment as well as the flank crowning and flank end relief are included in the numerical analysis process.

  10. Gear Fault Diagnosis Based on BP Neural Network

    Science.gov (United States)

    Huang, Yongsheng; Huang, Ruoshi

    2018-03-01

    Gear transmission is more complex, widely used in machinery fields, which form of fault has some nonlinear characteristics. This paper uses BP neural network to train the gear of four typical failure modes, and achieves satisfactory results. Tested by using test data, test results have an agreement with the actual results. The results show that the BP neural network can effectively solve the complex state of gear fault in the gear fault diagnosis.

  11. 50 CFR 622.31 - Prohibited gear and methods.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Prohibited gear and methods. 622.31... Management Measures § 622.31 Prohibited gear and methods. In addition to the prohibited gear/methods specified in this section, see §§ 622.33, 622.34, and 622.35 for seasonal/area prohibited gear/methods and...

  12. Mathematical Modelling of Involute Spur Gears Manufactured by Rack Cutter

    Directory of Open Access Journals (Sweden)

    Tufan Gürkan YILMAZ

    2016-05-01

    Full Text Available In this study, mathematical modelling of asymmetric involute spur gears was situated in by Litvin approach. In this context, firstly, mathematical expressions of rack cutter which manufacture asymmetric involute spur gear, then mathematical expression of asymmetric involute spur gear were obtained by using differential geometry, coordinate transformation and gear theory. Mathematical expressions were modelled in MATLAB and output files including points of involute spur gear’s teeth were designed automatically thanks to macros.

  13. Mass of the spirals galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Maupome, L; Pismis, P; Aguilar, L [Universidad Nacional Autonoma de Mexico, Mexico City. Inst. de Astronomia

    1981-01-01

    In an earlier paper we have found that the total mass of galaxies-especially of the spirals-based on values published until 1975, decreased as the Hubble type varied from Sa through Sc and Irregulars. It was also pointed out that masses determined from the hydrogen 21-cm line were higher than the optically determined masses. To investigate the cause of these tendencies we have estimated the masses using an analytic rotation curve of Brandt adjusted to the optical observations in order to include all the mass of a galaxy up to the last observed point. Although the masses computed in this manner were found to be larger, as expected, the decrease of mass with Hubble type found earlier is confirmed. However, there is a discrepancy in the earlier types (Sa, Sab) in that their radio-masses are smaller than the optically determined ones. At present, the cause of this is not clear.

  14. Characteristics of Reduction Gear in Electric Agricultural Vehicle

    Science.gov (United States)

    Choi, W. S.; Pratama, P. S.; Supeno, D.; Jeong, S. W.; Byun, J. Y.; Woo, J. H.; Lee, E. S.; Park, C. S.

    2018-03-01

    In electric agricultural machine a reduction gear is needed to convert the high speed rotation motion generated by DC motor to lower speed rotation motion used by the vehicle. The reduction gear consists of several spur gears. Spur gears are the most easily visualized gears that transmit motion between two parallel shafts and easy to produce. The modelling and simulation of spur gears in DC motor reduction gear is important to predict the actual motion behaviour. A pair of spur gear tooth in action is generally subjected to two types of cyclic stress: contact stress and bending stress. The stress may not attain their maximum values at the same point of contact fatigue. These types of failure can be minimized by analysis of the problem during the design stage and creating proper tooth surface profile with proper manufacturing methods. To improve its life expectation in this study modal and stress analysis of reduction gear is simulated using ANSYS workbench based on finite element method (FEM). The modal analysis was done to understand reduction gear deformation behaviour when vibration occurs. FEM static stress analysis is also simulated on reduction gear to simulate the gear teeth bending stress and contact stress behaviour.

  15. Gear cutting tools fundamentals of design and computation

    CERN Document Server

    Radzevich, Stephen P

    2010-01-01

    Presents the DG/K-based method of surface generation, a novel and practical mathematical method for designing gear cutting tools with optimal parameters. This book proposes a scientific classification for the various kinds of the gear machining meshes, discussing optimal designs of gear cutting tools.

  16. Intelligent Test Mechanism Design of Worn Big Gear

    Directory of Open Access Journals (Sweden)

    Hong-Yu LIU

    2014-10-01

    Full Text Available With the continuous development of national economy, big gear was widely applied in metallurgy and mine domains. So, big gear plays an important role in above domains. In practical production, big gear abrasion and breach take place often. It affects normal production and causes unnecessary economic loss. A kind of intelligent test method was put forward on worn big gear mainly aimed at the big gear restriction conditions of high production cost, long production cycle and high- intensity artificial repair welding work. The measure equations transformations were made on involute straight gear. Original polar coordinate equations were transformed into rectangular coordinate equations. Big gear abrasion measure principle was introduced. Detection principle diagram was given. Detection route realization method was introduced. OADM12 laser sensor was selected. Detection on big gear abrasion area was realized by detection mechanism. Tested data of unworn gear and worn gear were led in designed calculation program written by Visual Basic language. Big gear abrasion quantity can be obtained. It provides a feasible method for intelligent test and intelligent repair welding on worn big gear.

  17. Electrostatic microactuators with integrated gear linkages for mechanical power transmission

    NARCIS (Netherlands)

    Legtenberg, R.; Legtenberg, Rob; Berenschot, Johan W.; Elwenspoek, Michael Curt; Fluitman, J.H.J.

    1996-01-01

    In this paper a surface micromachining process is presented which has been used to fabricate electrostatic microactuators that are interconnected with each other and linked to other movable microstructures by integrated gear linkages. The gear linkages consist of rotational and linear gear

  18. 50 CFR 635.21 - Gear operation and deployment restrictions.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Gear operation and deployment restrictions....21 Gear operation and deployment restrictions. Link to an amendment published at 75 FR 57701, Sept. 22, 2010. The green-stick gear authorization requirements under paragraphs (c)(2)(v)(A), (c)(2)(v)(B...

  19. 46 CFR 182.610 - Main steering gear.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Main steering gear. 182.610 Section 182.610 Shipping...) MACHINERY INSTALLATION Steering Systems § 182.610 Main steering gear. (a) A vessel must be provided with a main steering gear that is: (1) Of adequate strength and capable of steering the vessel at all service...

  20. Gear shift map design methodology for automotive transmissions

    NARCIS (Netherlands)

    Ngo, Viet Dac; Hofman, Theo; Steinbuch, Maarten; Serrarens, Alex

    In this paper, a design methodology is developed to condtruct the gear shift map for the automotive transmissions used in conventional and hybrid electric vehicles. The methodology utilizes an optimal gear shift strategy to derive the optimal gear shift patterns over a wide range of driving

  1. 46 CFR 167.65-25 - Steering gear tests.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Steering gear tests. 167.65-25 Section 167.65-25... SHIPS Special Operating Requirements § 167.65-25 Steering gear tests. On all nautical school ships making voyages of more than 48 hours' duration, the entire steering gear, the whistle, the means of...

  2. 30 CFR 75.1404 - Automatic brakes; speed reduction gear.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Automatic brakes; speed reduction gear. 75.1404... Automatic brakes; speed reduction gear. [Statutory Provisions] Each locomotive and haulage car used in an... permit automatic brakes, locomotives and haulage cars shall be subject to speed reduction gear, or other...

  3. 46 CFR 61.20-1 - Steering gear.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Steering gear. 61.20-1 Section 61.20-1 Shipping COAST... Periodic Tests of Machinery and Equipment § 61.20-1 Steering gear. (a) The marine inspector must inspect the steering gear at each inspection for certification for vessels whose Certificate of Inspections...

  4. Evaluation Of Vibration-Monitoring Gear-Diagnostic System

    Science.gov (United States)

    Townsend, Dennis P.; Zakrajsek, James J.

    1995-01-01

    Report describes experimental evaluation of commercial electronic system designed to monitor vibration signal from accelerometer on gear-box to detect vibrations indicative of damage to gears. System includes signal-conditioning subsystem and personal computer in which analog-to-digital converter installed. Results show system fairly effective in detecting surface fatigue pits on spur-gear teeth.

  5. Analysis of landing gear noise during approach

    NARCIS (Netherlands)

    Merino Martinez, R.; Snellen, M.; Simons, D.G.

    2016-01-01

    Airframe noise is becoming increasingly important during approach, even reaching higher noise levels than the engines in some cases. More people are a_ected due to low ight altitudes and _xed tra_c routing associated with typical approaches. For most air- craft types, the landing gear system is a

  6. Energy efficiency improvement by gear shifting optimization

    Directory of Open Access Journals (Sweden)

    Blagojevic Ivan A.

    2013-01-01

    Full Text Available Many studies have proved that elements of driver’s behavior related to gear selection have considerable influence on the fuel consumption. Optimal gear shifting is a complex task, especially for inexperienced drivers. This paper presents an implemented idea for gear shifting optimization with the aim of fuel consumption minimization with more efficient engine working regimes. Optimized gear shifting enables the best possible relation between vehicle motion regimes and engine working regimes. New theoretical-experimental approach has been developed using On-Board Diagnostic technology which so far has not been used for this purpose. The matrix of driving modes according to which tests were performed is obtained and special data acquisition system and analysis process have been developed. Functional relations between experimental test modes and adequate engine working parameters have been obtained and all necessary operations have been conducted to enable their use as inputs for the designed algorithm. The created Model has been tested in real exploitation conditions on passenger car with Otto fuel injection engine and On-Board Diagnostic connection without any changes on it. The conducted tests have shown that the presented Model has significantly positive effects on fuel consumption which is an important ecological aspect. Further development and testing of the Model allows implementation in wide range of motor vehicles with various types of internal combustion engines.

  7. IMRT delivery verification using a spiral phantom

    International Nuclear Information System (INIS)

    Richardson, Susan L.; Tome, Wolfgang A.; Orton, Nigel P.; McNutt, Todd R.; Paliwal, Bhudatt R.

    2003-01-01

    In this paper we report on the testing and verification of a system for IMRT delivery quality assurance that uses a cylindrical solid water phantom with a spiral trajectory for radiographic film placement. This spiral film technique provides more complete dosimetric verification of the entire IMRT treatment than perpendicular film methods, since it samples a three-dimensional dose subspace rather than using measurements at only one or two depths. As an example, the complete analysis of the predicted and measured spiral films is described for an intracranial IMRT treatment case. The results of this analysis are compared to those of a single field perpendicular film technique that is typically used for IMRT QA. The comparison demonstrates that both methods result in a dosimetric error within a clinical tolerance of 5%, however the spiral phantom QA technique provides a more complete dosimetric verification while being less time consuming. To independently verify the dosimetry obtained with the spiral film, the same IMRT treatment was delivered to a similar phantom in which LiF thermoluminescent dosimeters were arranged along the spiral trajectory. The maximum difference between the predicted and measured TLD data for the 1.8 Gy fraction was 0.06 Gy for a TLD located in a high dose gradient region. This further validates the ability of the spiral phantom QA process to accurately verify delivery of an IMRT plan

  8. Stuck in gear: age-related loss of variable gearing in skeletal muscle.

    Science.gov (United States)

    Holt, Natalie C; Danos, Nicole; Roberts, Thomas J; Azizi, Emanuel

    2016-04-01

    Skeletal muscles power a broad diversity of animal movements, despite only being able to produce high forces over a limited range of velocities. Pennate muscles use a range of gear ratios, the ratio of muscle shortening velocity to fiber shortening velocity, to partially circumvent these force-velocity constraints. Muscles operate with a high gear ratio at low forces; fibers rotate to greater angles of pennation, enhancing velocity but compromising force. At higher forces, muscles operate with a lower gear ratio; fibers rotate little so limiting muscle shortening velocity, but helping to preserve force. This ability to shift gears is thought to be due to the interplay of contractile force and connective tissue constraints. In order to test this hypothesis, gear ratios were determined in the medial gastrocnemius muscles of both healthy young rats, and old rats where the interaction between contractile and connective tissue properties was assumed to be disrupted. Muscle fiber and aponeurosis stiffness increased with age (PGear ratio decreased with increasing force in young (Pgearing is lost in old muscle. These findings support the hypothesis that variable gearing results from the interaction between contractile and connective tissues and suggest novel explanations for the decline in muscle performance with age. © 2016. Published by The Company of Biologists Ltd.

  9. Application of the Electrical (Geophysical) Method for the Identification of the Sealed Bevel in the Coastal Region of Walidia Province of el Jadida - Morocco

    Science.gov (United States)

    Elfjiji, H.; Boukdir, A.; Zitouni, A.

    2018-05-01

    The Walidia area knows a great development of agricultural, industrial, maritime activities and a very great demographic expansion. This development is accompanied by a growing demand for water. On the other hand, any intense abstraction of fresh water at a coastal aquifer capture field causes a decrease in groundwater flow and a lowering of the piezometric surface. There is therefore a danger of advancing towards the land of the saltwater bevel and salinization of groundwater which is gradually loaded into mineral salts and can reach abnormally high levels. This work deals with the application of geophysics by electrical sounding method to the in-depth study of the freshwater-salt water interface (salted bevel) on the one hand and the study of the lateral and vertical evolution of the geometry of the different aquifers. The principle of the method is, when performing an electrical survey, to research how varies, at a given point on the surface, the resistivity of the subsoil vertically. For this one executes in a same place a succession of measurements, increasing each time the dimensions of the device and thus the depth of investigation which is proportional to them. At this site, we explore a slice of ground increasingly thick and thus highlights the changes in geological constitution along the vertical. The electrical soundings were carried out with the classic Schlumberger device. The interpretation and the exploitation of the data of the electric soundings carried out made it possible to : Follow the evolution of the salted bevel roof, Draw the upstream limit (marine invasion) of salted bevel Hauterivian, on the one hand, and Valanginian and Jurassic on the other hand, Follow the roof structure of Dridrat limestone (Hauterivien) and limestones of Valanginien and Upper Jurassic, Draw the map of the marl roof of Safi (Hauterivian) constituting the impermeable substratum of Dridrat limestones.

  10. Technologies for the marking of fishing gear to identify gear components entangled on marine animals and to reduce abandoned, lost or otherwise discarded fishing gear.

    Science.gov (United States)

    He, Pingguo; Suuronen, Petri

    2018-04-01

    Fishing gears are marked to establish and inform origin, ownership and position. More recently, fishing gears are marked to aid in capacity control, reduce marine litter due to abandoned, lost or otherwise discarded fishing gear (ALDFG) and assist in its recovery, and to combat illegal, unreported and unregulated (IUU) fishing. Traditionally, physical marking, inscription, writing, color, shape, and tags have been used for ownership and capacity purposes. Buoys, lights, flags, and radar reflectors are used for marking of position. More recently, electronic devices have been installed on marker buoys to enable easier relocation of the gear by owner vessels. This paper reviews gear marking technologies with focus on coded wire tags, radio frequency identification tags, Automatic Identification Systems, advanced electronic buoys for pelagic longlines and fish aggregating devices, and re-location technology if the gear becomes lost. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Dynamics of High-Speed Precision Geared Rotor Systems

    Directory of Open Access Journals (Sweden)

    Lim Teik C.

    2014-07-01

    Full Text Available Gears are one of the most widely applied precision machine elements in power transmission systems employed in automotive, aerospace, marine, rail and industrial applications because of their reliability, precision, efficiency and versatility. Fundamentally, gears provide a very practical mechanism to transmit motion and mechanical power between two rotating shafts. However, their performance and accuracy are often hampered by tooth failure, vibrations and whine noise. This is most acute in high-speed, high power density geared rotor systems, which is the primary scope of this paper. The present study focuses on the development of a gear pair mathematical model for use to analyze the dynamics of power transmission systems. The theory includes the gear mesh representation derived from results of the quasi-static tooth contact analysis. This proposed gear mesh theory comprising of transmission error, mesh point, mesh stiffness and line-of-action nonlinear, time-varying parameters can be easily incorporated into a variety of transmission system models ranging from the lumped parameter type to detailed finite element representation. The gear dynamic analysis performed led to the discovery of the out-of-phase gear pair torsion modes that are responsible for much of the mechanical problems seen in gearing applications. The paper concludes with a discussion on effectual design approaches to minimize the influence of gear dynamics and to mitigate gear failure in practical power transmission systems.

  12. Efficiency of fishing gears in the river Halda, Chittagong, Bangladesh

    Directory of Open Access Journals (Sweden)

    Mohammad Arshad-Ul-Alam

    2015-12-01

    Full Text Available To determine the catch efficiency of fishing gears, catch per unit effort (CPUEdata were collected for two years during January 2007 to December 2008 from the river Halda. Analyses were done to examine the variation of CPUE among gears, studied sections, months and years. The mean CPUE for pooled data of all gears was 2.247±0.265 kg.gear-1day-1 and 2.697±0.355 kg.gear-1day-1 for 2007 and 2008 respectively. Among eight gear categories, bag nets yielded the highest CPUE during 2007 (5.957±0.704 kg.gear-1day-1 and seine nets during 2008 (7.288±1.477 kg.gear-1day-1. Among 31 gear types, small meshed bag nets yielded the highest CPUE (18.065±6.660 and 15.69±4.479 kg.gear-1day-1 during 2007 and 2008 respectively. CPUE was highest during March-April and September-November periods. Analysis of variance showed significant difference among catch rates of different fishing gears. The CPUE differed significantly among different months for net fence, gill net, cast net and scoop net during 2007; and for seine net, net fence, bag net and cast net during 2008.

  13. Finite Element Residual Stress Analysis of Planetary Gear Tooth

    Directory of Open Access Journals (Sweden)

    Jungang Wang

    2013-01-01

    Full Text Available A method to simulate residual stress field of planetary gear is proposed. In this method, the finite element model of planetary gear is established and divided to tooth zone and profile zone, whose different temperature field is set. The gear's residual stress simulation is realized by the thermal compression stress generated by the temperature difference. Based on the simulation, the finite element model of planetary gear train is established, the dynamic meshing process is simulated, and influence of residual stress on equivalent stress of addendum, pitch circle, and dedendum of internal and external meshing planetary gear tooth profile is analyzed, according to non-linear contact theory, thermodynamic theory, and finite element theory. The results show that the equivalent stresses of planetary gear at both meshing and nonmeshing surface are significantly and differently reduced by residual stress. The study benefits fatigue cracking analysis and dynamic optimization design of planetary gear train.

  14. Power loss analysis in altered tooth-sum spur gearing

    Directory of Open Access Journals (Sweden)

    Sachidananda H. K.

    2018-01-01

    Full Text Available The main cause of power loss or dissipation of heat in case of meshed gears is due to friction existing between gear tooth mesh and is a major concern in low rotational speed gears, whereas in case of high operating speed the power loss taking place due to compression of air-lubricant mixture (churning losses and windage losses due to aerodynamic trial of air lubricant mixture which controls the total efficiency needs to be considered. Therefore, in order to improve mechanical efficiency it is necessary for gear designer during gear tooth optimization to consider these energy losses. In this research paper the power loss analysis for a tooth-sum of 100 altered by ±4% operating between a specified center distance is considered. The results show that negative altered tooth-sum gearing performs better as compared to standard and positive altered tooth-sum gearing.

  15. Modeling of automotive driveline system for reducing gear rattles

    Science.gov (United States)

    Shangguan, Wen-Bin; Liu, Xue-Lai; Yin, Yuming; Rakheja, Subhash

    2018-03-01

    A nonlinear torsional model for a driveline system with 4 degrees of freedom is proposed for studying gear rattle if a car is at idle. The time-varying meshing stiffness of geared teeth, gear backlash, and the damping from oil film are included in the model. The dynamic responses of the driveline system, such as clutch angular displacement, meshing force and relative displacement between geared teeth, are calculated using the presented model. The influences of stiffness and damping of a clutch on gear rattle of geared teeth in a generic transmission are investigated. Based on the calculation and analysis results, a design guideline to select clutch's stiffness and damping is developed to reduce gear rattle for a car at idle. Taking a generic driveline system of a passenger car as an example, the developed method is experimentally validated by comparing the baseline clutch and revised clutch, in terms of the measured noise inside engine compartment and cab and vibrations at transmission housing.

  16. Echo-Interleaved-Spiral MR Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Rosenthal, Shirrie; Azhari, Haim [Department of Biomedical Engineering, Technion, Israel Institute of Technology, Haifa 32000 (Israel); Montag, Avram [Elscint Ltd., MRI division, Haifa (Israel)

    1999-12-31

    Interleaved-Spiral imaging is an efficient method for MRI fast scans. However, images suffer from blurring and artifacts due to field inhomogeneities and the long readout times. In this paper, we combine interleaved-spirals with spin-echo for 3D scans. The refocusing RF-pulses (echoes) refocus off-resonance spins, thus allowing longer acquisition times per excitation, by limiting inhomogeneity effects. The total number of excitations for a 3D scan is reduced by half. The 3D Fourier transform of an object is divided into pairs of slices, one slice is scanned in an outgoing interleaved-spiral, initiated after a 90 degree pulse has been applied. The second slice is scanned in an ingoing interleaved-spiral, after a 180 degree pulse has been applied, thus reaching the slice origin at the echo time. (authors) 4 refs., 3 figs.

  17. Echo-Interleaved-Spiral MR Imaging

    International Nuclear Information System (INIS)

    Rosenthal, Shirrie; Azhari, Haim; Montag, Avram

    1998-01-01

    Interleaved-Spiral imaging is an efficient method for MRI fast scans. However, images suffer from blurring and artifacts due to field inhomogeneities and the long readout times. In this paper, we combine interleaved-spirals with spin-echo for 3D scans. The refocusing RF-pulses (echoes) refocus off-resonance spins, thus allowing longer acquisition times per excitation, by limiting inhomogeneity effects. The total number of excitations for a 3D scan is reduced by half. The 3D Fourier transform of an object is divided into pairs of slices, one slice is scanned in an outgoing interleaved-spiral, initiated after a 90 degree pulse has been applied. The second slice is scanned in an ingoing interleaved-spiral, after a 180 degree pulse has been applied, thus reaching the slice origin at the echo time. (authors)

  18. Corrosion of Spiral Rib Aluminized Pipe : [Summary

    Science.gov (United States)

    2012-01-01

    Large diameter, corrugated steel pipes are a common sight in the culverts that run alongside many Florida roads. Spiral-ribbed aluminized pipe (SRAP) has been widely specified by the Florida Department of Transportation (FDOT) for runoff drainage. Th...

  19. Corrosion of Spiral Rib Aluminized Pipe

    Science.gov (United States)

    2012-08-01

    Large diameter, corrugated steel pipes are a common sight in the culverts that run alongside many Florida roads. Spiral-ribbed aluminized pipe (SRAP) has been widely specified by the Florida Department of Transportation (FDOT) for runoff drainage. Th...

  20. Pulsatile spiral blood flow through arterial stenosis.

    Science.gov (United States)

    Linge, Fabian; Hye, Md Abdul; Paul, Manosh C

    2014-11-01

    Pulsatile spiral blood flow in a modelled three-dimensional arterial stenosis, with a 75% cross-sectional area reduction, is investigated by using numerical fluid dynamics. Two-equation k-ω model is used for the simulation of the transitional flow with Reynolds numbers 500 and 1000. It is found that the spiral component increases the static pressure in the vessel during the deceleration phase of the flow pulse. In addition, the spiral component reduces the turbulence intensity and wall shear stress found in the post-stenosis region of the vessel in the early stages of the flow pulse. Hence, the findings agree with the results of Stonebridge et al. (2004). In addition, the results of the effects of a spiral component on time-varying flow are presented and discussed along with the relevant pathological issues.

  1. Magnetic spiral arms in galaxy haloes

    Science.gov (United States)

    Henriksen, R. N.

    2017-08-01

    We seek the conditions for a steady mean field galactic dynamo. The parameter set is reduced to those appearing in the α2 and α/ω dynamo, namely velocity amplitudes, and the ratio of sub-scale helicity to diffusivity. The parameters can be allowed to vary on conical spirals. We analyse the mean field dynamo equations in terms of scale invariant logarithmic spiral modes and special exact solutions. Compatible scale invariant gravitational spiral arms are introduced and illustrated in an appendix, but the detailed dynamical interaction with the magnetic field is left for another work. As a result of planar magnetic spirals `lifting' into the halo, multiple sign changes in average rotation measures forming a regular pattern on each side of the galactic minor axis, are predicted. Such changes have recently been detected in the Continuum Halos in Nearby Galaxies-an EVLA Survey (CHANG-ES) survey.

  2. Statistical analysis of metallicity in spiral galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Galeotti, P [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica; Turin Univ. (Italy). Ist. di Fisica Generale)

    1981-04-01

    A principal component analysis of metallicity and other integral properties of 33 spiral galaxies is presented; the involved parameters are: morphological type, diameter, luminosity and metallicity. From the statistical analysis it is concluded that the sample has only two significant dimensions and additonal tests, involving different parameters, show similar results. Thus it seems that only type and luminosity are independent variables, being the other integral properties of spiral galaxies correlated with them.

  3. Galactic models with variable spiral structure

    International Nuclear Information System (INIS)

    James, R.A.; Sellwood, J.A.

    1978-01-01

    A series of three-dimensional computer simulations of disc galaxies has been run in which the self-consistent potential of the disc stars is supplemented by that arising from a small uniform Population II sphere. The models show variable spiral structure, which is more pronounced for thin discs. In addition, the thin discs form weak bars. In one case variable spiral structure associated with this bar has been seen. The relaxed discs are cool outside resonance regions. (author)

  4. SIGNATURES OF LONG-LIVED SPIRAL PATTERNS

    International Nuclear Information System (INIS)

    Martínez-García, Eric E.; González-Lópezlira, Rosa A.

    2013-01-01

    Azimuthal age/color gradients across spiral arms are a signature of long-lived spirals. From a sample of 19 normal (or weakly barred) spirals where we have previously found azimuthal age/color gradient candidates, 13 objects were further selected if a two-armed grand-design pattern survived in a surface density stellar mass map. Mass maps were obtained from optical and near-infrared imaging, by comparison with a Monte Carlo library of stellar population synthesis models that allowed us to obtain the mass-to-light ratio in the J band, (M/L) J , as a function of (g – i) versus (i – J) color. The selected spirals were analyzed with Fourier methods in search of other signatures of long-lived modes related to the gradients, such as the gradient divergence toward corotation, and the behavior of the phase angle of the two-armed spiral in different wavebands, as expected from theory. The results show additional signatures of long-lived spirals in at least 50% of the objects.

  5. Chiralities of spiral waves and their transitions.

    Science.gov (United States)

    Pan, Jun-ting; Cai, Mei-chun; Li, Bing-wei; Zhang, Hong

    2013-06-01

    The chiralities of spiral waves usually refer to their rotation directions (the turning orientations of the spiral temporal movements as time elapses) and their curl directions (the winding orientations of the spiral spatial geometrical structures themselves). Traditionally, they are the same as each other. Namely, they are both clockwise or both counterclockwise. Moreover, the chiralities are determined by the topological charges of spiral waves, and thus they are conserved quantities. After the inwardly propagating spirals were experimentally observed, the relationship between the chiralities and the one between the chiralities and the topological charges are no longer preserved. The chiralities thus become more complex than ever before. As a result, there is now a desire to further study them. In this paper, the chiralities and their transition properties for all kinds of spiral waves are systemically studied in the framework of the complex Ginzburg-Landau equation, and the general relationships both between the chiralities and between the chiralities and the topological charges are obtained. The investigation of some other models, such as the FitzHugh-Nagumo model, the nonuniform Oregonator model, the modified standard model, etc., is also discussed for comparison.

  6. Global Analysis of a Planetary Gear Train

    Directory of Open Access Journals (Sweden)

    Tongjie Li

    2014-01-01

    Full Text Available By using the Poincaré-like cell-to-cell mapping method and shooting method, the global characteristics of a planetary gear train are studied based on the torsional vibration model with errors of transmission, time-varying meshing stiffness, and multiple gear backlashes. The study results reveal that the planetary with a certain set of parameters has four coexisting periodic orbits, which are P-1, P-2, P-4, and P-8, respectively. P-1 and P-2 motions are not of long-term stability, P-8 motion is of local stability, and P-4 motion is of global stability. Shooting method does not have the capacity of searching coexisting periodic orbits in a global scope, and it is easy to omit some periodic orbits which are far away from the main gropes of periodic orbits.

  7. Geared Topological Metamaterials with Tunable Mechanical Stability

    Directory of Open Access Journals (Sweden)

    Anne S. Meeussen

    2016-11-01

    Full Text Available The classification of materials into insulators and conductors has been shaken up by the discovery of topological insulators that conduct robustly at the edge but not in the bulk. In mechanics, designating a material as insulating or conducting amounts to asking if it is rigid or floppy. Although mechanical structures that display topological floppy modes have been proposed, they are all vulnerable to global collapse. Here, we design and build mechanical metamaterials that are stable and yet capable of harboring protected edge and bulk modes, analogous to those in electronic topological insulators and Weyl semimetals. To do so, we exploit gear assemblies that, unlike point masses connected by springs, incorporate both translational and rotational degrees of freedom. Global structural stability is achieved by eliminating geometrical frustration of collective gear rotations extending through the assembly. The topological robustness of the mechanical modes makes them appealing across scales from engineered macrostructures to networks of toothed microrotors of potential use in micromachines.

  8. Spiral 2: preliminary design study

    International Nuclear Information System (INIS)

    2001-11-01

    The scientific council of GANIL asked to perform a comparative study on the production methods based on gamma induced fission and rapid-neutron induced fission concerning the nature and the intensity of the neutron-rich products. The production rate expected should be around 10 13 fissions per second. The study should include the implantation and the costs of the concerned accelerators. The scientific committee recommended also to study the possibility to re-inject the radioactive beams of SPIRAL-II in the cyclotrons available at GANIL in order to give access to an energy range from 1.7 to 100 MeV/nucleon. For that purpose, some study groups have been formed to evaluate the possibility of such a project in the different components: physics case, target-ion sources, drivers, post-acceleration and general infrastructure. The organization of the project study is given at the end of this report. The following report presents an overview of the study. Particularly the total costs have been assessed according to 3 options for the driver: 38.0*10 6 euros for a 40 MeV deuteron linac, 18.7*10 6 euros for a 45 MeV electron linac, and 29.1*10 6 euros for a 80 MeV deuteron cyclotron

  9. Spiral 2: preliminary design study

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-11-15

    The scientific council of GANIL asked to perform a comparative study on the production methods based on gamma induced fission and rapid-neutron induced fission concerning the nature and the intensity of the neutron-rich products. The production rate expected should be around 10{sup 13} fissions per second. The study should include the implantation and the costs of the concerned accelerators. The scientific committee recommended also to study the possibility to re-inject the radioactive beams of SPIRAL-II in the cyclotrons available at GANIL in order to give access to an energy range from 1.7 to 100 MeV/nucleon. For that purpose, some study groups have been formed to evaluate the possibility of such a project in the different components: physics case, target-ion sources, drivers, post-acceleration and general infrastructure. The organization of the project study is given at the end of this report. The following report presents an overview of the study. Particularly the total costs have been assessed according to 3 options for the driver: 38.0*10{sup 6} euros for a 40 MeV deuteron linac, 18.7*10{sup 6} euros for a 45 MeV electron linac, and 29.1*10{sup 6} euros for a 80 MeV deuteron cyclotron.

  10. Dark matter in spiral galaxies

    International Nuclear Information System (INIS)

    Albada, T.S. van; Sancisi, R.

    1986-01-01

    Mass models of spiral galaxies based on the observed light distribution, assuming constant M/L for bulge and disc, are able to reproduce the observed rotation curves in the inner regions, but fail to do so increasingly towards and beyond the edge of the visible material. The discrepancy in the outer region can be accounted for by invoking dark matter; some galaxies require at least four times as much dark matter as luminous matter. There is no evidence for a dependence on galaxy luminosity or morphological type. Various arguments support the idea that a distribution of visible matter with constant M/L is responsible for the circular velocity in the inner region, i.e. inside approximately 2.5 disc scalelengths. Luminous matter and dark matter seem to 'conspire' to produce the flat observed rotation curves in the outer region. It seems unlikely that this coupling between disc and halo results from the large-scale gravitational interaction between the two components. Attempts to determine the shape of dark halos have not yet produced convincing results. (author)

  11. Electrohydraulic drive system with planetary superposed gears

    Energy Technology Data Exchange (ETDEWEB)

    Graetz, A.; Klimek, K.H.; Welz, H.

    1989-01-01

    To prevent drive problems in ploughs the drives must be designed in such a way as to compensate for asymmetries. If electromechanical drives are replaced by an electrohydraulic drive system with superposed planetary gears and hydrostatic torque reaction supports the following advantages occur: load-free acceleration, load equalisation between main and auxiliary drive, overload protection, and reduction of systems vibrations. 2 figs., 2 tabs.

  12. Generating Cycloidal Gears for 3D Printing

    OpenAIRE

    Daniels, Sunny

    2016-01-01

    (Shortened version of abstract in article itself) This article describes an algorithm for producing, for any desired resolution and any desired numbers of wheel and pinion teeth, polygonal approximations to the shapes of a pair of cycloidal gears that mesh correctly. An Octave implementation of the algorithm, mostly written in 2014, is included. The Octave implementation contains a (crude, but evidently adequate, at least for reasonable numbers of wheel and pinion teeth) solution of the probl...

  13. Six Decades of Spiral Density Wave Theory

    Science.gov (United States)

    Shu, Frank H.

    2016-09-01

    The theory of spiral density waves had its origin approximately six decades ago in an attempt to reconcile the winding dilemma of material spiral arms in flattened disk galaxies. We begin with the earliest calculations of linear and nonlinear spiral density waves in disk galaxies, in which the hypothesis of quasi-stationary spiral structure (QSSS) plays a central role. The earliest success was the prediction of the nonlinear compression of the interstellar medium and its embedded magnetic field; the earliest failure, seemingly, was not detecting color gradients associated with the migration of OB stars whose formation is triggered downstream from the spiral shock front. We give the reasons for this apparent failure with an update on the current status of the problem of OB star formation, including its relationship to the feathering substructure of galactic spiral arms. Infrared images can show two-armed, grand design spirals, even when the optical and UV images show flocculent structures. We suggest how the nonlinear response of the interstellar gas, coupled with overlapping subharmonic resonances, might introduce chaotic behavior in the dynamics of the interstellar medium and Population I objects, even though the underlying forces to which they are subject are regular. We then move to a discussion of resonantly forced spiral density waves in a planetary ring and their relationship to the ideas of disk truncation, and the shepherding of narrow rings by satellites orbiting nearby. The back reaction of the rings on the satellites led to the prediction of planet migration in protoplanetary disks, which has had widespread application in the exploding data sets concerning hot Jupiters and extrasolar planetary systems. We then return to the issue of global normal modes in the stellar disk of spiral galaxies and its relationship to the QSSS hypothesis, where the central theoretical concepts involve waves with negative and positive surface densities of energy and angular

  14. A Generalized Dynamic Model of Geared System: Establishment and Application

    Directory of Open Access Journals (Sweden)

    Hui Liu

    2011-12-01

    Full Text Available In order to make the dynamic characteristic simulation of the ordinary and planetary gears drive more accurate and more efficient , a generalized dynamic model of geared system is established including internal and external mesh gears in this paper. It is used to build a mathematical model, which achieves the auto judgment of the gear mesh state. We do not need to concern about active or passive gears any more, and the complicated power flow analysis can be avoided. With the numerical integration computation, the axis orbits diagram and dynamic gear mesh force characteristic are acquired and the results show that the dynamic response of translational displacement is greater when contacting line direction change is considered, and with the quickly change of direction of contacting line, the amplitude of mesh force would be increased, which easily causes the damage to the gear tooth. Moreover, compared with ordinary gear, dynamic responses of planetary gear would be affected greater by the gear backlash. Simulation results show the effectiveness of the generalized dynamic model and the mathematical model.

  15. DESIGN IMPROVEMENT OF THE LOCOMOTIVE RUNNING GEARS

    Directory of Open Access Journals (Sweden)

    S. V. Myamlin

    2013-09-01

    Full Text Available Purpose. To determine the dynamic qualities of the mainline freight locomotives characterizing the safe motion in tangent and curved track sections at all operational speeds, one needs a whole set of studies, which includes a selection of the design scheme, development of the corresponding mathematical model of the locomotive spatial fluctuations, construction of the computer calculation program, conducting of the theoretical and then experimental studies of the new designs. In this case, one should compare the results with existing designs. One of the necessary conditions for the qualitative improvement of the traction rolling stock is to define the parameters of its running gears. Among the issues related to this problem, an important place is occupied by the task of determining the locomotive dynamic properties on the stage of projection, taking into account the selected technical solutions in the running gear design. Methodology. The mathematical modeling studies are carried out by the numerical integration method of the dynamic loading for the mainline locomotive using the software package «Dynamics of Rail Vehicles » («DYNRAIL». Findings. As a result of research for the improvement of locomotive running gear design it can be seen that the creation of the modern locomotive requires from engineers and scientists the realization of scientific and technical solutions. The solutions enhancing design speed with simultaneous improvement of the traction, braking and dynamic qualities to provide a simple and reliable design, especially the running gear, reducing the costs for maintenance and repair, low initial cost and operating costs for the whole service life, high traction force when starting, which is as close as possible to the ultimate force of adhesion, the ability to work in multiple traction mode and sufficient design speed. Practical Value. The generalization of theoretical, scientific and methodological, experimental studies aimed

  16. Određivanje krutosti planetarnog prenosnika / Determination of gear mesh stiffness in planetary gearing

    Directory of Open Access Journals (Sweden)

    Vojislav Batinić

    2008-04-01

    Full Text Available Kontaktna krutost zubaca jedan je od glavnih generatora unutrašnjih dinamičkih sila u spregama zupčanika planetarnih prenosnika. Neophodan je pri opisivanju dinamičkog ponašanja planetarnih prenosnika, tj. pri postavljanju jednačina dinamičke ravnoteže. U radu je prikazan metodološki pristup analitičkom i eksperimentalnom određivanju krutosti posmatranog planetarnog prenosnika. / Gear mesh stiffness in planetary gearing is one of the main generators of internal dynamic forces. It is necessary in describing dynamic behavior of planetary trains, i.e. in defining their equations of dynamic balance. This paper presents a methodological approach to experimental and analytical calculation of stiffness in planetary gearing.

  17. Influence of material and gear parameters on the safety of gearing in metallurgical industry

    Directory of Open Access Journals (Sweden)

    S. Medvecká - Beňová

    2015-01-01

    Full Text Available This paper deals with the appropriate choice of parameters to obtain the desired level of safety of gears in a gearbox to drive the conveyor in the metallurgical industry under increased load. Steel with surface hardness up to 350 HBW, or heat treated steel with hardness of 500 - 650 HBW are used. As a final heat treatment are used surface hardening, cementation and hardening, nitridation. Good properties of heat-treated steels are at the correct thickness of the heat-treated layer of the tooth. Results are presented for dual-ratio gearbox with spur gears from operation of an integrated steel company.

  18. Magnet-Sleeve-Sealed Mini Trochoidal-Gear Pump Prototype with Polymer Composite Gear

    Directory of Open Access Journals (Sweden)

    Pedro Javier Gamez-Montero

    2017-09-01

    Full Text Available The trochoidal-gear technology has been growing in groundbreaking fields. Forthcoming applications are demanding to this technology a step forward in the conceiving stage of positive displacement machines. The compendium of the qualities and the inherent characteristics of trochoidal-gear technology, especially towards the gerotor pump, together with scale/size factor and magnetic-driven transmission has led to the idea of a magnet-sleeve-sealed variable flow mini trochoidal-gear pump. From its original concept, to the last phase of the design development, the proof of concept, this new product will intend to overcome problems such as noise, vibration, maintenance, materials, and dimensions. The paper aims to show the technological path followed from the concept, design, and model, to the manufacture of the first prototype, where the theoretical and numerical approaches are not always directly reflected in the prototype performance results. Early in the design process, from a standard-commercial sintered metal mini trochoidal-gear unit, fundamental characteristics and dimensional limitations have been evaluated becoming the strategic parameters that led to its configuration. The main technical challenge to confront is being sealed with non-exterior driveshaft, ensuring that the whole interior is filled and wetted with working fluid and helping the hydrodynamic film formation, the pumping effect, and the heat dissipation. Subsequently, the mini pump architecture, embodiment, methodology, materials, and manufacture are presented. The trend of applications of polymer composite materials and their benefits wanted to be examined with this new mini pump prototype, and a pure polyoxymethylene mini trochoidal-gear set has been designed and manufactured. Finally, both the sintered and the polymer trochoidal-gear units have been experimentally tested in an in-house full-instrumented mini test bench. Although the main goal of the presented work is the

  19. Investigation of logarithmic spiral nanoantennas at optical frequencies

    Science.gov (United States)

    Verma, Anamika; Pandey, Awanish; Mishra, Vigyanshu; Singh, Ten; Alam, Aftab; Dinesh Kumar, V.

    2013-12-01

    The first study is reported of a logarithmic spiral antenna in the optical frequency range. Using the finite integration technique, we investigated the spectral and radiation properties of a logarithmic spiral nanoantenna and a complementary structure made of thin gold film. A comparison is made with results for an Archimedean spiral nanoantenna. Such nanoantennas can exhibit broadband behavior that is independent of polarization. Two prominent features of logarithmic spiral nanoantennas are highly directional far field emission and perfectly circularly polarized radiation when excited by a linearly polarized source. The logarithmic spiral nanoantenna promises potential advantages over Archimedean spirals and could be harnessed for several applications in nanophotonics and allied areas.

  20. Bifurcation phenomena in internal dynamics of gear systems

    Directory of Open Access Journals (Sweden)

    Hortel M.

    2007-10-01

    Full Text Available The impact effects in gear mesh represent specific phenomena in the dynamic investigation of highspeed light transmission systems with kinematic couplings. They are caused of greater dynamic than static elastic deformations in meshing gear profiles. In term of internal dynamics they are influenced among others by time heteronomous stiffness functions in gear mesh and resonance tuning of stiffness level. The damping in gear mesh and in gear system is concerned significantly in the amplitude progress, greatness and phase shift of relative motion towards stiffness function alternatively towards its modify form in gear mesh. In consequence of these and another actions rise above resonance characteristics certain singular locations with jump amplitude course.

  1. Nonlinear dynamics modelling of multistage micro-planetary gear transmission

    Directory of Open Access Journals (Sweden)

    Li Jianying

    2018-01-01

    Full Text Available The transmission structure of a 2K-H multistage micro-planetary gear transmission reducer is described in detail, and three assumptions are supposed in dynamic modelling. On basis of these assumptions, a three stages 2K-H micro-planetary gear transmission dynamic model is established, in which the relative displacement each meshing gear pairs can be obtained after including the comprehensive transmission error. According to gear kinematics, the friction arms between the sun gear, the ring gear and the nth planet are also obtained, and the friction coefficient in the mixed elastohydrodynamic lubrication is considered, the transmission system motion differential equations are obtained, including above factors and the time-varying meshing stiffness, damping and backlash, inter-stage coupling stiffness, it can be provided an theoretical foundation for further analysing the parameter sensitivity, dynamic stability and designing.

  2. Prediction of potential failures in hydraulic gear pumps

    Directory of Open Access Journals (Sweden)

    E. Lisowski

    2010-07-01

    Full Text Available Hydraulic gear pumps are used in many machines and devices. In hydraulic systems of machines gear pumps are main component ofsupply unit or perform auxiliary function. Gear pumps opposite to vane pumps are less complicated. They consists of such components as:housing, gear wheels, bearings, shaft, seal for rotation motion which are not very sensitive for damage and that is why they are using veryoften. However, gear pumps are break down from time to time. Usually damage of pump cause shutting down of machines and devices.One of the way for identifying potential failures and foreseeing their effects is a quality method. On the basis of these methods apreventing action might be undertaken before failure appear. In this paper potential failures and damages of a gear pump were presented bythe usage of matrix FMEA analysis.

  3. Economic method for helical gear flank surface characterisation

    Science.gov (United States)

    Koulin, G.; Reavie, T.; Frazer, R. C.; Shaw, B. A.

    2018-03-01

    Typically the quality of a gear pair is assessed based on simplified geometric tolerances which do not always correlate with functional performance. In order to identify and quantify functional performance based parameters, further development of the gear measurement approach is required. Methodology for interpolation of the full active helical gear flank surface, from sparse line measurements, is presented. The method seeks to identify the minimum number of line measurements required to sufficiently characterise an active gear flank. In the form ground gear example presented, a single helix and three profile line measurements was considered to be acceptable. The resulting surfaces can be used to simulate the meshing engagement of a gear pair and therefore provide insight into functional performance based parameters. Therefore the assessment of the quality can be based on the predicted performance in the context of an application.

  4. Galaxy Zoo: dust in spiral galaxies

    Science.gov (United States)

    Masters, Karen L.; Nichol, Robert; Bamford, Steven; Mosleh, Moein; Lintott, Chris J.; Andreescu, Dan; Edmondson, Edward M.; Keel, William C.; Murray, Phil; Raddick, M. Jordan; Schawinski, Kevin; Slosar, Anže; Szalay, Alexander S.; Thomas, Daniel; Vandenberg, Jan

    2010-05-01

    We investigate the effect of dust on spiral galaxies by measuring the inclination dependence of optical colours for 24276 well-resolved Sloan Digital Sky Survey (SDSS) galaxies visually classified via the Galaxy Zoo project. We find clear trends of reddening with inclination which imply a total extinction from face-on to edge-on of 0.7, 0.6, 0.5 and 0.4mag for the ugri passbands (estimating 0.3mag of extinction in z band). We split the sample into `bulgy' (early-type) and `discy' (late-type) spirals using the SDSS fracdeV (or fDeV) parameter and show that the average face-on colour of `bulgy' spirals is redder than the average edge-on colour of `discy' spirals. This shows that the observed optical colour of a spiral galaxy is determined almost equally by the spiral type (via the bulge-disc ratio and stellar populations), and reddening due to dust. We find that both luminosity and spiral type affect the total amount of extinction, with discy spirals at Mr ~ -21.5mag having the most reddening - more than twice as much as both the lowest luminosity and most massive, bulge-dominated spirals. An increase in dust content is well known for more luminous galaxies, but the decrease of the trend for the most luminous has not been observed before and may be related to their lower levels of recent star formation. We compare our results with the latest dust attenuation models of Tuffs et al. We find that the model reproduces the observed trends reasonably well but overpredicts the amount of u-band attenuation in edge-on galaxies. This could be an inadequacy in the Milky Way extinction law (when applied to external galaxies), but more likely indicates the need for a wider range of dust-star geometries. We end by discussing the effects of dust on large galaxy surveys and emphasize that these effects will become important as we push to higher precision measurements of galaxy properties and their clustering. This publication has been made possible by the participation of more than

  5. Analysis of spiral components in 16 galaxies

    International Nuclear Information System (INIS)

    Considere, S.; Athanassoula, E.

    1988-01-01

    A Fourier analysis of the intensity distributions in the plane of 16 spiral galaxies of morphological types from 1 to 7 is performed. The galaxies processed are NGC 300,598,628,2403,2841,3031,3198,3344,5033,5055,5194,5247,6946,7096,7217, and 7331. The method, mathematically based upon a decomposition of a distribution into a superposition of individual logarithmic spiral components, is first used to determine for each galaxy the position angle PA and the inclination ω of the galaxy plane onto the sky plane. Our results, in good agreement with those issued from different usual methods in the literature, are discussed. The decomposition of the deprojected galaxies into individual spiral components reveals that the two-armed component is everywhere dominant. Our pitch angles are then compared to the previously published ones and their quality is checked by drawing each individual logarithmic spiral on the actual deprojected galaxy images. Finally, the surface intensities for angular periodicities of interest are calculated. A choice of a few of the most important ones is used to elaborate a composite image well representing the main spiral features observed in the deprojected galaxies

  6. Prediction of Landing Gear Noise Reduction and Comparison to Measurements

    Science.gov (United States)

    Lopes, Leonard V.

    2010-01-01

    Noise continues to be an ongoing problem for existing aircraft in flight and is projected to be a concern for next generation designs. During landing, when the engines are operating at reduced power, the noise from the airframe, of which landing gear noise is an important part, is equal to the engine noise. There are several methods of predicting landing gear noise, but none have been applied to predict the change in noise due to a change in landing gear design. The current effort uses the Landing Gear Model and Acoustic Prediction (LGMAP) code, developed at The Pennsylvania State University to predict the noise from landing gear. These predictions include the influence of noise reduction concepts on the landing gear noise. LGMAP is compared to wind tunnel experiments of a 6.3%-scale Boeing 777 main gear performed in the Quiet Flow Facility (QFF) at NASA Langley. The geometries tested in the QFF include the landing gear with and without a toboggan fairing and the door. It is shown that LGMAP is able to predict the noise directives and spectra from the model-scale test for the baseline configuration as accurately as current gear prediction methods. However, LGMAP is also able to predict the difference in noise caused by the toboggan fairing and by removing the landing gear door. LGMAP is also compared to far-field ground-based flush-mounted microphone measurements from the 2005 Quiet Technology Demonstrator 2 (QTD 2) flight test. These comparisons include a Boeing 777-300ER with and without a toboggan fairing that demonstrate that LGMAP can be applied to full-scale flyover measurements. LGMAP predictions of the noise generated by the nose gear on the main gear measurements are also shown.

  7. Landing Gear Door Liners for Airframe Noise Reduction

    Science.gov (United States)

    Jones, Michael G. (Inventor); Howerton, Brian M. (Inventor); Van De Ven, Thomas (Inventor)

    2014-01-01

    A landing gear door for retractable landing gear of aircraft includes an acoustic liner. The acoustic liner includes one or more internal cavities or chambers having one or more openings that inhibit the generation of sound at the surface and/or absorb sound generated during operation of the aircraft. The landing gear door may include a plurality of internal chambers having different geometries to thereby absorb broadband noise.

  8. Diagnostics of power transmissions system with tooth gear

    Directory of Open Access Journals (Sweden)

    Grzegorz WOJNAR

    2008-01-01

    Full Text Available This paper presents results of laboratory tests that were aimed at detecting early stages of various faults in toothed wheels by measurement and analysis of transverse vibration speed of the transmission gear shafts. In experimental investigation, cracking of the root tooth and chipping of the tooth were detected. The laser vibrometer Ometron VH300+ was used for non-contact measurement of shaft transversal vibration speed. Gear vibrations were recorded in selected points of gear housing and gear shafts at different speeds and gear loads. Results were analyzed and compared but in this paper is presented only selected examples. This paper shows that on the basis of the transverse vibration speed of transmission gear shafts, it is possible to detect defects at an earlier stage than on the basis of the housing vibration accelerations. In the case of measuring gear shaft vibration velocity, the way of the signal generated by the defect of a gear wheel (or bearing is shortened as well as the influence of composed transmittance of the bearing-gear housing system is eliminated. WV time-frequency analysis and complex continuous wavelet transformations were used for detection. The authors introduced a measure of local tooth damage, which was proportional to the size of damage. The results of research presented in this paperconfirmed that the defect's measure is very sensitive to the development of teeth faults.

  9. Turbine Engine with Differential Gear Driven Fan and Compressor

    Science.gov (United States)

    Suciu, Gabriel L. (Inventor); Pagluica, Gino J. (Inventor); Duong, Loc Quang (Inventor); Portlock, Lawrence E. (Inventor)

    2013-01-01

    A gas turbine engine provides a differential gear system coupling the turbine to the bypass fan and the compressor. In this manner, the power/speed split between the bypass fan and the compressor can be optimized under all conditions. In the example shown, the turbine drives a sun gear, which drives a planet carrier and a ring gear in a differential manner. One of the planet carrier and the ring gear is coupled to the bypass fan, while the other is coupled to the compressor.

  10. The theory and practice of worm gear drives

    CERN Document Server

    Dudás, Ilés

    2005-01-01

    Worm gears are special gears that resemble screws, and can be used to drive other gears. Worm gears, enable two non-touching shafts in a machine to mesh (join) together. This publication, unique in that it combines both theoretical and practical design aspects, including the latest results of research and development, provides detailed treatment of the theory and production of worm drives, as well as the overarching subject of production geometry of helicoidal surfaces.Included are mathematical models for a number of practical applications; a description of dressing equipment r

  11. Offset Compound Gear Inline Two-Speed Drive

    Science.gov (United States)

    Stevens, Mark A. (Inventor); Handschuh, Robert F. (Inventor); Lewicki, David G. (Inventor)

    2014-01-01

    A two-speed transmission having an input shaft and an output shaft, the transmission being capable of transitioning between fixed ratios, the high-range ratio being direct 1:1 and the low-range ratio being about 2:1. The transmission is a simple lightweight, yet robust, configuration utilizing only two gear meshes, being comprised of an input gear, a cluster gear, and an output gear. The transmission is controlled with a clutch and a sprag and with the input and output shafts turning in the same direction.

  12. Gear-shaft linkage, especially for nuclear reactor coolant pumps

    International Nuclear Information System (INIS)

    Delaunois, T.; Lefevre, R.

    1990-01-01

    The pump comprises: - inlet and outlet channels for the pumped fluid - a rotating shaft - a gear wheel mounted on the shaft by an axial locking nut which can support the axial hydraulic force - a thermal barrier above the gear wheel. A hydrostatic bearing fitted to the exterior surround of the gear wheel, the gear shaft linkage is made by at least a centering and locating device having a cylindrical span and an axial stop and another independent device which can take up the torque [fr

  13. Sharp corners as sources of spiral pairs

    International Nuclear Information System (INIS)

    Biton, Y.; Rabinovitch, A.; Braunstein, D.; Friedman, M.; Aviram, I.

    2010-01-01

    It is demonstrated that using the FitzHugh-Nagumo model, stimulation of excitable media inside a region possessing sharp corners, can lead to the appearance of sources of spiral-pairs of sustained activity. The two conditions for such source creation are: The corners should be less than 120 deg. and the range of stimulating amplitudes should be small, occurring just above the threshold value and decreasing with the corner angle. The basic mechanisms driving the phenomenon are discussed. These include: A. If the corner angle is below 120 deg., the wave generated inside cannot emerge at the corner tip, resulting in the creation of two free edges which start spiraling towards each other. B. Spiraling must be strong enough; otherwise annihilation of the rotating arms would occur too soon to create a viable source. C. The intricacies of the different radii involved are elucidated. Possible applications in heart stimulation and in chemical reactions are considered.

  14. Principles of spiral CT: III. Quality assurance

    International Nuclear Information System (INIS)

    Suess, C.; Kalender, W.A.

    1998-01-01

    Since its introduction in 1989 spiral CT has gained wide clinical acceptance and meanwhile it covers a large range of CT applications. This new technology, however, has not yet been recognized and acknowledged in the national or international regulations on scanner quality assurance (QA) programs. The conventional QA procedures should be extended to check the distribution of resolution and noise within the image plane. Imaging performance in the axial direction constitutes one of the major advantages of spiral scanning. Therefore, the slice sensitivity profiles and the spatial and low-contrast resolution along the z-axis have to be assessed. The high demands on table feed accuracy require additional tests. We suggest phantoms and procedures to check and quantify these parameters. Thereby, we hope to support the ongoing discussion about spiral CT quality assurance. (orig.) [de

  15. Spiral loaded cavities for heavy ion acceleration

    International Nuclear Information System (INIS)

    Schempp, A.; Klein, H.

    1976-01-01

    A transmission line theory of the spiral resonator has been performed and the calculated and measured properties will be compared. Shunt impedances up to 50 MΩ/m have been measured. In a number of high power tests the structure has been tested and its electrical and mechanical stability has been investigated. The static frequency shift due to ponderomotoric forces was between 0.2 and 50 kHz/kW dependent on the geometrical parameters of the spirals. The maximum field strength obtained on the axis was 16 MV/m in pulsed operation and 9.2 MV/m in cw, corresponding to a voltage gain per cavity of up to 0.96 MV. The results show that spiral resonators are well suited as heavy ion accelerator cavities. (author)

  16. Organic carbon spiralling in stream ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Newbold, J D; Mulholland, P J; Elwood, J W; O' Neill, R V

    1982-01-01

    The term spiralling has been used to describe the combined processes of cycling and longitudinal transport in streams. As a measure or organic carbon spiralling, we introduced organic carbon turnover length, S, defined as the average or expected downstream distance travelled by a carbon atom between its entry or fixation in the stream and its oxidation. Using a simple model for organic carbon dynamics in a stream, we show that S is closely related to fisher and Likens' ecosystem efficiency. Unlike efficiency, however, S is independent of the length of the study reach, and values of S determined in streams of differing lengths can be compared. Using data from three different streams, we found the relationship between S and efficiency to agree closely with the model prediction. Hypotheses of stream functioning are discussed in the context of organic carbeon spiralling theory.

  17. Spiral arms, comets and terrestrial catastrophism

    International Nuclear Information System (INIS)

    Clube, S.V.M.; Napier, W.M.

    1982-01-01

    A review is presented of an hypothesis of terrestrial catastrophism in which comets grow in molecular clouds and are captured by the Sun as it passes through the spiral arms of the Galaxy. Assuming that comets are a major supplier of the Earth-crossing (Appollo) asteroid population, the latter fluctuates correspondingly and leads to episodes of terrestrial bombardment. Changes in the rotational momentum of core and mantle, generated by impacts, lead to episodes of magnetic field reversal and tectonic activity, while surface phenomena lead to ice-ages and mass extinctions. An episodic geophysical history with an interstellar connection is thus implied. If comets in spiral arms are necessary intermediaries in the process of star formation, the theory also has implications relating to early solar system history and galactic chemistry. These aspects are briefly discussed with special reference to the nature of spiral arms. (author)

  18. Considerations of an oscillating spiral universe cosmology

    International Nuclear Information System (INIS)

    Sachs, M.

    1989-01-01

    It is proposed that if the spiral configuration of galaxies is explicable in terms of the equations of motion of its constituent stars, as an expression of global laws of nature, then the universe as a whole may be similarly described in terms of the motions of its constituent galaxies with a similar spiral dynamics. With the functional form of the spiral paths in terms of Fresnel integrals, taken from solutions of equations in general relativity (from previous analyses of galactic configurations) the density of the universe at the big bang stage is determined. It is found to depend, numerically, on the neutron lifetime and the period of oscillation of the universe as a whole. There is some concluding discussion of the implications of this analysis of the matter of the universe at the big bang stage vis a vis the black hole state of matter

  19. Molecular clouds and galactic spiral structure

    International Nuclear Information System (INIS)

    Dame, T.M.

    1984-02-01

    Galactic CO line emission at 115 GHz was surveyed in order to study the distribution of molecular clouds in the inner galaxy. Comparison of this survey with similar H1 data reveals a detailed correlation with the most intense 21 cm features. To each of the classical 21 cm H1 spiral arms of the inner galaxy there corresponds a CO molecular arm which is generally more clearly defined and of higher contrast. A simple model is devised for the galactic distribution of molecular clouds. The modeling results suggest that molecular clouds are essentially transient objects, existing for 15 to 40 million years after their formation in a spiral arm, and are largely confined to spiral features about 300 pc wide

  20. Spiral CT manifestations of spherical pneumonia

    International Nuclear Information System (INIS)

    Li Xiaohong; Yang Hongwei; Xu Chunmin; Qin Xiu

    2008-01-01

    Objective: To explore the Spiral CT manifestations and differential diagnosis of spherical pneumonia. Methods: 18 cases of spherical pneumonia and 20 cases of peripheral pulmonary carcinoma were selected, both of them were confirmed by clinic and/or pathology. The SCT findings of both groups were compared retrospectively. Results: Main spiral CT findings of spherical pneumonia were showed as followings: square or triangular lesions adjacent to pleura; with irregular shape, blurry, slightly lobulated margin, sometimes with halo sign. Small inflammatory patches and intensified vascular markings around the lesions were seen. Lesions became smaller or vanished after short-term anti-inflammatory treatment. Conclusion: Spherical pneumonia showed some characteristics on Spiral CT scan, which are helpful in diagnosis and differential diagnosis of this disease. (authors)

  1. Spiral CT for evaluation of chest trauma

    International Nuclear Information System (INIS)

    Roehnert, W.; Weise, R.

    1997-01-01

    After implementation of spiral CT in our department, we carried out an analysis for determining anew the value of CT as a modality of chest trauma diagnosis in the emergency department. The retrospective study covers a period of 10 months and all emergency patients with chest trauma exmined by spiral CT. The major lesions of varying seriousness covered by this study are: pneumothorax, hematothorax, pulmonary contusion or laceration, mediastinal hematoma, rupture of a vessel, injury of the heart and pericardium. The various fractures are not included in this study. In many cases, spiral CT within relatively short time yields significant diagnostic findings, frequently saving additional angiography. A rigid diagnostic procedure cannot be formulated. Plain-film chest radiography still remains a diagnostic modality of high value. (Orig.) [de

  2. Simulations of the flocculent spiral M33: what drives the spiral structure?

    Science.gov (United States)

    Dobbs, C. L.; Pettitt, A. R.; Corbelli, E.; Pringle, J. E.

    2018-05-01

    We perform simulations of isolated galaxies in order to investigate the likely origin of the spiral structure in M33. In our models, we find that gravitational instabilities in the stars and gas are able to reproduce the observed spiral pattern and velocity field of M33, as seen in HI, and no interaction is required. We also find that the optimum models have high levels of stellar feedback which create large holes similar to those observed in M33, whilst lower levels of feedback tend to produce a large amount of small scale structure, and undisturbed long filaments of high surface density gas, hardly detected in the M33 disc. The gas component appears to have a significant role in producing the structure, so if there is little feedback, both the gas and stars organise into clear spiral arms, likely due to a lower combined Q (using gas and stars), and the ready ability of cold gas to undergo spiral shocks. By contrast models with higher feedback have weaker spiral structure, especially in the stellar component, compared to grand design galaxies. We did not see a large difference in the behaviour of Qstars with most of these models, however, because Qstars stayed relatively constant unless the disc was more strongly unstable. Our models suggest that although the stars produce some underlying spiral structure, this is relatively weak, and the gas physics has a considerable role in producing the large scale structure of the ISM in flocculent spirals.

  3. Neutrons for science (NFS) at spiral-2

    International Nuclear Information System (INIS)

    Ridikas, D.

    2005-01-01

    Both cross section measurements and various applications could be realised successfully using the high energy neutrons that will be produced at SPIRAL-2. Two particular cases were examined in more detail, namely: (a) neutron time-of-flight (nToF) measurements with pulsed neutron beams, and (b) material activation-irradiation with high-energy high-intensity neutron fluxes. Thanks to the high energy and high intensity neutron flux available, SPIRAL-2 offers a unique opportunity for material irradiations both for fission and fusion related research, tests of various detection systems and of resistance of electronics components to irradiations, etc. SPIRAL-2 also could be considered as an intermediate step towards new generation dedicated irradiation facilities as IFMIF previewed only beyond 2015. Equally, the interval from 0.1 MeV to 40 MeV for neutron cross section measurements is an energy range that is of particular importance for energy applications, notably accelerator driven systems (ADS) and Gen-IV fast reactors, as well as for fusion related devices. It is also the region where pre-equilibrium approaches are often used to link the low (evaporation) and high energy (intra-nuclear cascade) reaction models. With very intense neutron beams of SPIRAL-2 measurements of very low mass (often radioactive) targets and small cross sections become feasible in short experimental campaigns. Production of radioactive targets for dedicated physics experiments is also an attractive feature of SPIRAL-2. In brief, it was shown that SPIRAL-2 has got a remarkable potential for neutron based research both for fundamental physics and various applications. In addition, in the neutron energy range from a few MeV to, say, 35 MeV this research would have a leading position for the next 10-15 years if compared to other neutron facilities in operation or under construction worldwide. (author)

  4. Kidney spiral CT, indications, realization, results

    International Nuclear Information System (INIS)

    Braunschweig, R.; Beilicke, M.; Hundt, W.; Breiteneder, T.; Reiser, M.

    1999-01-01

    The introduction of spiral computed tomography (spiral CT) has vastly enriched the methodologically diversity of computer-tomographic scans. It allows for the recording of different perfusion or excretion stages of the kidney parenchyma of the urine draining paths by carrying out long-distance, phase-identical multiple examinations of the retroperitoneum. The description of the findings which are characterized by their local and contrasts behavior is possible. The following report describes the indications and technological process of kidney spiral CT using kidney-typical intravenous contrast media. Special emphasis is put on the advantages and limits of multiple phase spiral CT. Decisive preconditions are: 1. Specific clinical query, 2. selection of the corresponding phase contrasts of the kidneys and uretra or bladder, 3. exact technical and temporal adjustment of the acquisition parameters. Scanning times are in the range of seconds. The overall examination can be carried out quick and without any major strain on the part of the patient. A sound proof and a general differentiation of focal kideny lesions can be derived from the acquired data. This is also true for kidneys and ureters findings. Bladder findings can be localized and differentiated according to stage. More than two 'spiral acquisitions' should be carried out with restraint taking exposure to radiation into account. Due to the sound registration of focal lesions, its capability of reproduction and its short-time examination, the spiral CT of the kidneys can be said to be the most effective current scanning method of the retroperitoneum following clinical examinations and sonography. (orig.) [de

  5. Graphite target for the spiral project

    International Nuclear Information System (INIS)

    Putaux, J.C.; Ducourtieux, M.; Ferro, A.; Foury, P.; Kotfila, L.; Mueller, A.C.; Obert, J.; Pauwels, N.; Potier, J.C.; Proust, J.; Loiselet, M.

    1996-01-01

    A study of the thermal and physical properties of graphite targets for the SPIRAL project is presented. The main objective is to develop an optimized set-up both mechanically and thermally resistant, presenting good release properties (hot targets with thin slices). The results of irradiation tests concerning the mechanical and thermal resistance of the first prototype of SPIRAL target with conical geometry are presented. The micro-structural properties of the graphite target is also studied, in order to check that the release properties are not deteriorated by the irradiation. Finally, the results concerning the latest pilot target internally heated by an electrical current are shown. (author)

  6. Packing of equal discs on a parabolic spiral lattice

    International Nuclear Information System (INIS)

    Xudong, F.; Bursill, L.A.; Julin, P.

    1989-01-01

    A contact disc model is investigated to determine the most closely-packed parabolic spiral lattice. The most space-efficient packings have divergence angles in agreement with the priority ranking of natural spiral structures

  7. Fishing gear-related injury in California marine wildlife.

    Science.gov (United States)

    Dau, Brynie Kaplan; Gilardi, Kirsten V K; Gulland, Frances M; Higgins, Ali; Holcomb, Jay B; Leger, Judy St; Ziccardi, Michael H

    2009-04-01

    We reviewed medical records from select wildlife rehabilitation facilities in California to determine the prevalence of injury in California Brown Pelicans (Pelecanus occidentalis), gulls (Larus spp.), and pinniped species (Zalophus californianus, Mirounga angustirostris, and Phoca vitulina) due to fishing gear entanglement and ingestion from 2001 to 2006. Of 9,668 Brown Pelican, gull, and pinniped cases described during the 6-yr study period (2001-06), 1,090 (11.3%) were fishing gear-related. Pelican injuries caused by fishing gear were most common in the Monterey Bay region, where 59.6% of the pelicans rescued in this area and admitted to a rehabilitation center were injured by fishing gear over the 6-yr period. The highest prevalence of fishing gear-related injury in gulls was documented in the Los Angeles/Orange County region (16.1%), whereas the highest prevalences in pinnipeds were seen in the San Diego region (3.7%). Despite these higher prevalences of gull and pinniped fishing gear-related injuries in these specific regions, there was no statistical significance in these trends. Juvenile gulls and pinnipeds were more commonly injured by fishing gear than adults (gulls: P = 0.03, odds ratio = 1.29; pinnipeds: P = 0.01, odds ratio = 2.07). Male pinnipeds were twice as likely to be injured by fishing gear as females (P gear-related injury cases that were successfully rehabilitated and released (percentage of cases successfully rehabilitated to the point of release out of the total number of fishing gear-related injury cases) was high in all three species groups (pelicans: 63%; gulls: 54%; pinnipeds: 70%). Fishing gear-related injuries in Brown Pelicans and gulls were highest in the fall, but there was only a significant difference between seasons for fishing gear-related injuries in pelicans. Fishing gear-related injuries in pinnipeds most commonly occurred in summer; however, a statistical difference was not detected between seasons for pinnipeds. Derelict

  8. Variable gearing in a biologically inspired pneumatic actuator array

    International Nuclear Information System (INIS)

    Azizi, Emanuel; Roberts, Thomas J

    2013-01-01

    A fundamental feature of pennate muscles is that muscle fibers are oriented at an angle to the line of action and rotate as they shorten, becoming more oblique throughout a contraction. This change in fiber orientation (pennation angle) can amplify the shortening velocity of a fiber and increase output velocity of the muscle. The velocity advantage resulting from dynamic changes in pennation angle can be characterized as a gear ratio (muscle velocity/fiber velocity). A recent study has shown that a pennate muscle's gear ratio varies automatically depending on the load such that a muscle operates with a high gear during rapid contractions and low gear during forceful contractions. We examined whether this variable gearing behavior can be replicated in a pennate array of artificial muscles. We used McKibben type pneumatic actuators, which shorten in tension when filled with compressed gas. Similar to muscle fibers, the actuators expand radially during shortening, a feature thought to be a critical part of the variable gearing mechanism in pennate muscles. We arranged McKibben actuators in an array oriented to mimic a pennate muscle, and quantified the system's gear ratio during contraction against a range of loads. Video was used to measure the gear ratio during each contraction. We find that similar to pennate muscles, the gear ratio decreases significantly with increasing load and that variable gearing results from load-dependent variation in the amount of actuator rotation. These results support the idea that variable gearing in pennate muscles is mediated by difference is fiber rotation and the direction of muscle bulging. The behavior of our artificial muscle array also highlights the potential benefits of bio-inspired architectures in artificial muscle arrays, including the ability to vary force and speed automatically in response to variable loading conditions. (paper)

  9. Variable gearing in a biologically inspired pneumatic actuator array.

    Science.gov (United States)

    Azizi, Emanuel; Roberts, Thomas J

    2013-06-01

    A fundamental feature of pennate muscles is that muscle fibers are oriented at an angle to the line of action and rotate as they shorten, becoming more oblique throughout a contraction. This change in fiber orientation (pennation angle) can amplify the shortening velocity of a fiber and increase output velocity of the muscle. The velocity advantage resulting from dynamic changes in pennation angle can be characterized as a gear ratio (muscle velocity/fiber velocity). A recent study has shown that a pennate muscle's gear ratio varies automatically depending on the load such that a muscle operates with a high gear during rapid contractions and low gear during forceful contractions. We examined whether this variable gearing behavior can be replicated in a pennate array of artificial muscles. We used McKibben type pneumatic actuators, which shorten in tension when filled with compressed gas. Similar to muscle fibers, the actuators expand radially during shortening, a feature thought to be a critical part of the variable gearing mechanism in pennate muscles. We arranged McKibben actuators in an array oriented to mimic a pennate muscle, and quantified the system's gear ratio during contraction against a range of loads. Video was used to measure the gear ratio during each contraction. We find that similar to pennate muscles, the gear ratio decreases significantly with increasing load and that variable gearing results from load-dependent variation in the amount of actuator rotation. These results support the idea that variable gearing in pennate muscles is mediated by difference is fiber rotation and the direction of muscle bulging. The behavior of our artificial muscle array also highlights the potential benefits of bio-inspired architectures in artificial muscle arrays, including the ability to vary force and speed automatically in response to variable loading conditions.

  10. VARIABLE GEARING IN A BIOLOGICALLY-INSPIRED PNEUMATIC ACTUATOR ARRAY

    Science.gov (United States)

    Azizi, Emanuel; Roberts, Thomas J.

    2013-01-01

    A fundamental feature of pennate muscles is that muscle fibers are oriented at an angle to the line of action and rotate as they shorten, becoming more oblique throughout a contraction. This change in fiber orientation (pennation angle) can amplify the shortening velocity of a fiber and increase output velocity of the muscle. The velocity advantage resulting from dynamic changes in pennation angle can be characterized as a gear ratio (muscle velocity/fiber velocity). A recent study has shown that a pennate muscle’s gear ratio varies automatically depending on the load such that a muscle operates with a high gear during rapid contractions and low gear during forceful contractions. We examined whether this variable gearing behavior can be replicated in a pennate array of artificial muscles. We used McKibben type pneumatic actuators, which shorten in tension when filled with compressed gas. Similar to muscle fibers, the actuators expand radially during shortening, a feature thought to be a critical part of the variable gearing mechanism in pennate muscles. We arranged McKibben actuators in an array oriented to mimic a pennate muscle, and quantified the system’s gear ratio during contraction against a range of loads. Video was used to measure the gear ratio during each contraction. We find that similar to pennate muscles, the gear ratio decreases significantly with increasing load and that variable gearing results from load-dependent variation in the amount of actuator rotation. These results support the idea that variable gearing in pennate muscles is mediated by difference is fiber rotation and the direction of muscle bulging. The behavior of our artificial muscle array also highlights the potential benefits of bio-inspired architectures in artificial muscle arrays, including the ability to vary force and speed automatically in response to variable loading conditions. PMID:23462288

  11. 78 FR 17188 - Agency Information Collection Activities; Comment Request; Evaluation of the GEAR UP College...

    Science.gov (United States)

    2013-03-20

    ...; Comment Request; Evaluation of the GEAR UP College Savings Account Research Demonstration AGENCY... of Collection: Evaluation of the GEAR UP College Savings Account Research Demonstration. OMB Control..., Gaining Early Awareness and Readiness for Undergraduate Programs (GEAR UP). This first Information...

  12. The dynamics of the spiral galaxy M81

    International Nuclear Information System (INIS)

    Visser, H.C.D.

    1978-01-01

    A detailed comparison of the observations of the spiral galaxy M81 with the density-wave theory for tightly-wound spirals is presented. In particular, hydrogen-line observations are compared with the nonlinear density-wave theory for the gas with the aim of constructing a density-wave model for the spiral galaxy M81

  13. Adaptation of the control system in view of SPIRAL integration

    International Nuclear Information System (INIS)

    Lecorche, E.

    1998-01-01

    As soon as the collaboration between the SPIRAL project and the Control Group has been defined, the first implementation of the SPIRAL control system started following various directions. Both the global hardware and software architectures has been specified and some practical works have been undertaken such as the Ethernet network installation or the first SPIRAL oriented software design and coding. (authors)

  14. Survey gear calibration independent of spatial fish distribution

    DEFF Research Database (Denmark)

    Lewy, Peter; Nielsen, J. Rasmus; Hovgård, Holger

    2004-01-01

    Trawl surveys provide important information for evaluation of relative stock abundance fluctuations over time. Therefore, when survey gears or vessels are changed, it is important to compare the efficiency and selectivity of old and new gears and vessels. A method for estimation of conversion fac...

  15. Contact stress analysis of involute spur gear by Finite Element ...

    African Journals Online (AJOL)

    In this paper the contact stress in rolling-sliding contact of involute spur gear and the effect of coefficient of friction was analyzed. To achieve this, first, three dimensional involute spur gear pairs were developed in Solid works 2012 Premium and the 3D model was exported to ANSYS workbench 14.5. Next, the analysis was ...

  16. Adaptive landing gear concept—feedback control validation

    Science.gov (United States)

    Mikulowski, Grzegorz M.; Holnicki-Szulc, Jan

    2007-12-01

    The objective of this paper is to present an integrated feedback control concept for adaptive landing gears (ALG) and its experimental validation. Aeroplanes are subjected to high dynamic loads as a result of the impact during each landing. Classical landing gears, which are in common use, are designed in accordance with official regulations in a way that ensures the optimal energy dissipation for the critical (maximum) sink speed. The regulations were formulated in order to ensure the functional capability of the landing gears during an emergency landing. However, the landing gears, whose characteristics are optimized for these critical conditions, do not perform well under normal impact conditions. For that situation it is reasonable to introduce a system that would adapt the characteristics of the landing gears according to the sink speed of landing. The considered system assumes adaptation of the damping force generated by the landing gear, which would perform optimally in an emergency situation and would adapt itself for regular landings as well. This research covers the formulation and design of the control algorithms for an adaptive landing gear based on MR fluid, implementation of the algorithms on an FPGA platform and experimental verification on a lab-scale landing gear device. The main challenge of the research was to develop a control methodology that could operate effectively within 50 ms, which is assumed to be the total duration of the phenomenon. The control algorithm proposed in this research was able to control the energy dissipation process on the experimental stand.

  17. Nonlinear Vibroimpact Characteristics of a Planetary Gear Transmission System

    Directory of Open Access Journals (Sweden)

    Jianxing Zhou

    2016-01-01

    Full Text Available In order to research the vibroimpact characteristics of a planetary gear transmission system under high speed and lightly loaded conditions, a new modeling method is proposed. In the modeling process, linear spring was used to simulate gear mesh elasticity under heavy load cases, and Hertz contact theory was used to calculate the contact force of gear pair under light load cases. Then, effects of the working conditions on the system vibroimpact characteristics are analyzed. The results show that, with input speed growing, the mesh force produced obvious fluctuations on the resonance frequencies of the sun gear and carrier torsion vibration, ring gear’s transverse vibration under the heavy load. Under light load condition, the collision vibration occurs in the gear pair; the changing trend of the contact force shows strongly nonlinear characteristics. The time of mesh-apart in gears pair decreases gradually as the load is increased; until it reaches collision vibration threshold value, the gear pair is no longer mesh-apart. With increasing of the input speed, the time of mesh-apart is decreased gradually; the fluctuation amplitude of contact force shows a linearly increasing trend. The study provides useful theoretical guideline for planetary gear transmission low-noise design.

  18. 49 CFR 229.57 - Foundation brake gear.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Foundation brake gear. 229.57 Section 229.57 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Foundation brake gear. A lever, rod, brake beam, hanger, or pin may not be worn through more than 30 percent...

  19. Potential for Landing Gear Noise Reduction on Advanced Aircraft Configurations

    Science.gov (United States)

    Thomas, Russell H.; Nickol, Craig L.; Burley, Casey L.; Guo, Yueping

    2016-01-01

    The potential of significantly reducing aircraft landing gear noise is explored for aircraft configurations with engines installed above the wings or the fuselage. An innovative concept is studied that does not alter the main gear assembly itself but does shorten the main strut and integrates the gear in pods whose interior surfaces are treated with acoustic liner. The concept is meant to achieve maximum noise reduction so that main landing gears can be eliminated as a major source of airframe noise. By applying this concept to an aircraft configuration with 2025 entry-into-service technology levels, it is shown that compared to noise levels of current technology, the main gear noise can be reduced by 10 EPNL dB, bringing the main gear noise close to a floor established by other components such as the nose gear. The assessment of the noise reduction potential accounts for design features for the advanced aircraft configuration and includes the effects of local flow velocity in and around the pods, gear noise reflection from the airframe, and reflection and attenuation from acoustic liner treatment on pod surfaces and doors. A technical roadmap for maturing this concept is discussed, and the possible drag increase at cruise due to the addition of the pods is identified as a challenge, which needs to be quantified and minimized possibly with the combination of detailed design and application of drag reduction technologies.

  20. Spiral kicker for the beam abort system

    Energy Technology Data Exchange (ETDEWEB)

    Martin, R.L.

    1983-01-01

    A brief study was carried out to determine the feasibility of a special kicker to produce a damped spiral beam at the beam dump for the beam abort system. There appears to be no problem with realizing this concept at a reasonably low cost.

  1. Spiral kicker for the beam abort system

    International Nuclear Information System (INIS)

    Martin, R.L.

    1983-01-01

    A brief study was carried out to determine the feasibility of a special kicker to produce a damped spiral beam at the beam dump for the beam abort system. There appears to be no problem with realizing this concept at a reasonably low cost

  2. Irrational Numbers Can "In-Spiral" You

    Science.gov (United States)

    Lewis, Leslie D.

    2007-01-01

    This article describes the instructional process of helping students visualize irrational numbers. Students learn to create a spiral, called "the wheel of Theodorus," which demonstrates irrational and rational lengths. Examples of student work help the reader appreciate the delightful possibilities of this project. (Contains 4 figures.)

  3. Importance of packing in spiral defect chaos

    Indian Academy of Sciences (India)

    We develop two measures to characterize the geometry of patterns exhibited by the state of spiral defect chaos, a weakly turbulent regime of Rayleigh-Bénard convection. These describe the packing of contiguous stripes within the pattern by quantifying their length and nearest-neighbor distributions. The distributions ...

  4. Spiral CT-angiography of the aorta

    NARCIS (Netherlands)

    Balm, R.; Eikelboom, B. C.; van Leeuwen, M. S.; Noordzij, J.

    1994-01-01

    AIMS: To determine whether the new technique of CT-angiography was accurate in displaying the complex anatomy of the aorta and its major branches. METHODS: Seventeen patients with a variety of aortic pathology were examined. Using a spiral CT-scanner a volumetric scan was made during injection of

  5. STRUCTURED MOLECULAR GAS REVEALS GALACTIC SPIRAL ARMS

    Energy Technology Data Exchange (ETDEWEB)

    Sawada, Tsuyoshi [Joint ALMA Office, Alonso de Cordova 3107, Vitacura, Santiago 763-0355 (Chile); Hasegawa, Tetsuo [NAOJ Chile Observatory, Joaquin Montero 3000 Oficina 702, Vitacura, Santiago 763-0409 (Chile); Koda, Jin, E-mail: sawada.tsuyoshi@nao.ac.jp [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States)

    2012-11-01

    We explore the development of structures in molecular gas in the Milky Way by applying the analysis of the brightness distribution function and the brightness distribution index (BDI) in the archival data from the Boston University-Five College Radio Astronomy Observatory {sup 13}CO J = 1-0 Galactic Ring Survey. The BDI measures the fractional contribution of spatially confined bright molecular emission over faint emission extended over large areas. This relative quantity is largely independent of the amount of molecular gas and of any conventional, pre-conceived structures, such as cores, clumps, or giant molecular clouds. The structured molecular gas traced by higher BDI is located continuously along the spiral arms in the Milky Way in the longitude-velocity diagram. This clearly indicates that molecular gas changes its structure as it flows through the spiral arms. Although the high-BDI gas generally coincides with H II regions, there is also some high-BDI gas with no/little signature of ongoing star formation. These results support a possible evolutionary sequence in which unstructured, diffuse gas transforms itself into a structured state on encountering the spiral arms, followed by star formation and an eventual return to the unstructured state after the spiral arm passage.

  6. Investigation of Spiral and Sweeping Holes

    Science.gov (United States)

    Thurman, Douglas; Poinsatte, Philip; Ameri, Ali; Culley, Dennis; Raghu, Surya; Shyam, Vikram

    2015-01-01

    Surface infrared thermography, hotwire anemometry, and thermocouple surveys were performed on two new film cooling hole geometries: spiral/rifled holes and fluidic sweeping holes. The spiral holes attempt to induce large-scale vorticity to the film cooling jet as it exits the hole to prevent the formation of the kidney shaped vortices commonly associated with film cooling jets. The fluidic sweeping hole uses a passive in-hole geometry to induce jet sweeping at frequencies that scale with blowing ratios. The spiral hole performance is compared to that of round holes with and without compound angles. The fluidic hole is of the diffusion class of holes and is therefore compared to a 777 hole and Square holes. A patent-pending spiral hole design showed the highest potential of the non-diffusion type hole configurations. Velocity contours and flow temperature were acquired at discreet cross-sections of the downstream flow field. The passive fluidic sweeping hole shows the most uniform cooling distribution but suffers from low span-averaged effectiveness levels due to enhanced mixing. The data was taken at a Reynolds number of 11,000 based on hole diameter and freestream velocity. Infrared thermography was taken for blowing rations of 1.0, 1.5, 2.0, and 2.5 at a density ration of 1.05. The flow inside the fluidic sweeping hole was studied using 3D unsteady RANS.

  7. High-displacement spiral piezoelectric actuators

    Science.gov (United States)

    Mohammadi, F.; Kholkin, A. L.; Jadidian, B.; Safari, A.

    1999-10-01

    A high-displacement piezoelectric actuator, employing spiral geometry of a curved piezoelectric strip is described. The monolithic actuators are fabricated using a layered manufacturing technique, fused deposition of ceramics, which is capable of prototyping electroceramic components with complex shapes. The spiral actuators (2-3 cm in diameter) consisted of 4-5 turns of a lead zirconate titanate ceramic strip with an effective length up to 28 cm. The width was varied from 0.9 to 1.75 mm with a height of 3 mm. When driven by the electric field applied across the width of the spiral wall, the tip of the actuator was found to displace in both radial and tangential directions. The tangential displacement of the tip was about 210 μm under the field of 5 kV/cm. Both the displacement and resonant frequency of the spirals could be tailored by changing the effective length and wall width. The blocking force of the actuator in tangential direction was about 1 N under the field of 5 kV/cm. These properties are advantageous for high-displacement low-force applications where bimorph or monomorph actuators are currently employed.

  8. Biofouling of spiral wound membrane systems

    NARCIS (Netherlands)

    Vrouwenvelder, J.S.

    2009-01-01

    Biofouling of spiral wound membrane systems High quality drinking water can be produced with membrane filtration processes like reverse osmosis (RO) and nanofiltration (NF). Because the global demand for fresh clean water is increasing, these membrane technologies will increase in importance in the

  9. Space charge effect in the spiral inflector

    International Nuclear Information System (INIS)

    Toprek, Dragan

    2000-01-01

    This paper presents the analytical and numerical theory of the space charge effects in the beam in the spiral inflector. It considers a simplified model of a 'straight' cylindrical beam by using a uniform particle distribution. Numerical results represented in this paper are obtained by using a modified version of the program CASINO

  10. Some optical properties of the spiral inflector

    International Nuclear Information System (INIS)

    Toprek, Dragan; Subotic, Krunoslav

    1999-01-01

    This paper compares some optical properties of different spiral inflectors using the program CASINO. The electric field distribution in the inflectors has been numerically calculated from an electric potential map produced by the program RELAX3D. The magnetic field is assumed to be constant. We have also made an effort to minimize the inflector fringe field using the RELAX3D program. (author)

  11. A nutrient’s downstream spiral

    Science.gov (United States)

    Indicators of a stream’s ability to remove nutrients provide insights on watershed integrity and stream habitat characteristics that are needed to help managers to restore stream ecosystem services. We used the Tracer Additon Spiraling Characterization Curve (TASCC) to mea...

  12. Spiral groove seal. [for hydraulic rotating shaft

    Science.gov (United States)

    Ludwig, L. P. (Inventor)

    1973-01-01

    Mating flat surfaces inhibit leakage of a fluid around a stationary shaft. A spiral groove pattern produces a pumping action toward the fluid when the shaft rotates which prevents leakage while a generated hydraulic lifting force separates the mating surfaces to minimize wear.

  13. Logarithmic spiral trajectories generated by Solar sails

    Science.gov (United States)

    Bassetto, Marco; Niccolai, Lorenzo; Quarta, Alessandro A.; Mengali, Giovanni

    2018-02-01

    Analytic solutions to continuous thrust-propelled trajectories are available in a few cases only. An interesting case is offered by the logarithmic spiral, that is, a trajectory characterized by a constant flight path angle and a fixed thrust vector direction in an orbital reference frame. The logarithmic spiral is important from a practical point of view, because it may be passively maintained by a Solar sail-based spacecraft. The aim of this paper is to provide a systematic study concerning the possibility of inserting a Solar sail-based spacecraft into a heliocentric logarithmic spiral trajectory without using any impulsive maneuver. The required conditions to be met by the sail in terms of attitude angle, propulsive performance, parking orbit characteristics, and initial position are thoroughly investigated. The closed-form variations of the osculating orbital parameters are analyzed, and the obtained analytical results are used for investigating the phasing maneuver of a Solar sail along an elliptic heliocentric orbit. In this mission scenario, the phasing orbit is composed of two symmetric logarithmic spiral trajectories connected with a coasting arc.

  14. The Spiral Curriculum. Research into Practice

    Science.gov (United States)

    Johnston, Howard

    2012-01-01

    The Spiral Curriculum is predicated on cognitive theory advanced by Jerome Bruner (1960), who wrote, "We begin with the hypothesis that any subject can be taught in some intellectually honest form to any child at any stage of development." In other words, even the most complex material, if properly structured and presented, can be understood by…

  15. Spiral Growth in Plants: Models and Simulations

    Science.gov (United States)

    Allen, Bradford D.

    2004-01-01

    The analysis and simulation of spiral growth in plants integrates algebra and trigonometry in a botanical setting. When the ideas presented here are used in a mathematics classroom/computer lab, students can better understand how basic assumptions about plant growth lead to the golden ratio and how the use of circular functions leads to accurate…

  16. The Spiral-Interactive Program Evaluation Model.

    Science.gov (United States)

    Khaleel, Ibrahim Adamu

    1988-01-01

    Describes the spiral interactive program evaluation model, which is designed to evaluate vocational-technical education programs in secondary schools in Nigeria. Program evaluation is defined; utility oriented and process oriented models for evaluation are described; and internal and external evaluative factors and variables that define each…

  17. The handedness of historiated spiral columns.

    Science.gov (United States)

    Couzin, Robert

    2017-09-01

    Trajan's Column in Rome (AD 113) was the model for a modest number of other spiral columns decorated with figural, narrative imagery from antiquity to the present day. Most of these wind upwards to the right, often with a congruent spiral staircase within. A brief introductory consideration of antique screw direction in mechanical devices and fluted columns suggests that the former may have been affected by the handedness of designers and the latter by a preference for symmetry. However, for the historiated columns that are the main focus of this article, the determining factor was likely script direction. The manner in which this operated is considered, as well as competing mechanisms that might explain exceptions. A related phenomenon is the reversal of the spiral in a non-trivial number of reproductions of the antique columns, from Roman coinage to Renaissance and baroque drawings and engravings. Finally, the consistent inattention in academic literature to the spiral direction of historiated columns and the repeated publication of erroneous earlier reproductions warrants further consideration.

  18. Nobeyama CO Atlas of Nearby Spiral Galaxies

    Science.gov (United States)

    Kuno, N.; Nakai, N.; Sorai, K.; Sato, N..; Yamauchi, A.; Tosaki, T.; Shioya, Y.; Vila-Vilaró, B.; Nishiyama, K.; Ishihara, Y.; Cepa, J.

    BEARS is a 25-beam focal plane array receiver mounted on the Nobeyama 45-m telescope. The combination of the large dish size of the telescope with the excellent performance of this receiver makes it an ideal tool for mapping observations of extended regions of the sky. We present here one of its current applications in a CO mapping survey of nearby spiral galaxies.

  19. Surface micromachined counter-meshing gears discrimination device

    Science.gov (United States)

    Polosky, Marc A.; Garcia, Ernest J.; Allen, James J.

    2000-12-12

    A surface micromachined Counter-Meshing Gears (CMG) discrimination device which functions as a mechanically coded lock. Each of two CMG has a first portion of its perimeter devoted to continuous driving teeth that mesh with respective pinion gears. Each EMG also has a second portion of its perimeter devoted to regularly spaced discrimination gear teeth that extend outwardly on at least one of three levels of the CMG. The discrimination gear teeth are designed so as to pass each other without interference only if the correct sequence of partial rotations of the CMG occurs in response to a coded series of rotations from the pinion gears. A 24 bit code is normally input to unlock the device. Once unlocked, the device provides a path for an energy or information signal to pass through the device. The device is designed to immediately lock up if any portion of the 24 bit code is incorrect.

  20. Study of a spur gear dynamic behavior in transient regime

    Science.gov (United States)

    Khabou, M. T.; Bouchaala, N.; Chaari, F.; Fakhfakh, T.; Haddar, M.

    2011-11-01

    In this paper the dynamic behavior of a single stage spur gear reducer in transient regime is studied. Dynamic response of the single stage spur gear reducer is investigated at different rotating velocities. First, gear excitation is induced by the motor torque and load variation in addition to the fluctuation of meshing stiffness due to the variation of input rotational speed. Then, the dynamic response is computed using the Newmark method. After that, a parameter study is made on spur gear powered in the first place by an electric motor and in the second place by four strokes four cylinders diesel engine. Dynamic responses come to confirm a significant influence of the transient regime on the dynamic behavior of a gear set, particularly in the case of engine acyclism condition.

  1. GEAR: A database of Genomic Elements Associated with drug Resistance

    Science.gov (United States)

    Wang, Yin-Ying; Chen, Wei-Hua; Xiao, Pei-Pei; Xie, Wen-Bin; Luo, Qibin; Bork, Peer; Zhao, Xing-Ming

    2017-01-01

    Drug resistance is becoming a serious problem that leads to the failure of standard treatments, which is generally developed because of genetic mutations of certain molecules. Here, we present GEAR (A database of Genomic Elements Associated with drug Resistance) that aims to provide comprehensive information about genomic elements (including genes, single-nucleotide polymorphisms and microRNAs) that are responsible for drug resistance. Right now, GEAR contains 1631 associations between 201 human drugs and 758 genes, 106 associations between 29 human drugs and 66 miRNAs, and 44 associations between 17 human drugs and 22 SNPs. These relationships are firstly extracted from primary literature with text mining and then manually curated. The drug resistome deposited in GEAR provides insights into the genetic factors underlying drug resistance. In addition, new indications and potential drug combinations can be identified based on the resistome. The GEAR database can be freely accessed through http://gear.comp-sysbio.org. PMID:28294141

  2. Spiral CT for evaluation of chest trauma; Spiral-CT beim Thoraxtrauma

    Energy Technology Data Exchange (ETDEWEB)

    Roehnert, W. [Universitaetsklinikum Dresden (Germany). Inst. und Poliklinik fuer Radiologische Diagnostik; Weise, R. [Universitaetsklinikum Dresden (Germany). Inst. und Poliklinik fuer Radiologische Diagnostik

    1997-07-01

    After implementation of spiral CT in our department, we carried out an analysis for determining anew the value of CT as a modality of chest trauma diagnosis in the emergency department. The retrospective study covers a period of 10 months and all emergency patients with chest trauma exmined by spiral CT. The major lesions of varying seriousness covered by this study are: pneumothorax, hematothorax, pulmonary contusion or laceration, mediastinal hematoma, rupture of a vessel, injury of the heart and pericardium. The various fractures are not included in this study. In many cases, spiral CT within relatively short time yields significant diagnostic findings, frequently saving additional angiography. A rigid diagnostic procedure cannot be formulated. Plain-film chest radiography still remains a diagnostic modality of high value. (Orig.) [Deutsch] Nach Einfuehrung der Spiral-CT in unserer Einrichtung versuchten wir, den Stellenwert der Computertomographie in der Notfalldiagnostik des Thoraxtraumas neu zu bestimmen. Dazu wurden retrospektiv ueber einen Zeitraum von 10 Monaten alle mittels Spiral-CT untersuchten Notfallpatienten mit Thoraxverletzungen ausgewertet. Im Vordergrund standen folgende Befunde unterschiedlichen Schweregrades: Pneumothorax, Haematothorax, Lungenkontusion/-lazeration, Mediastinalhaematom, Gefaessruptur, Herz- und Herzbeutelverletzung. Auf die unterschiedlichen Frakturen wird bewusst nicht naeher eingegangen. In vielen Faellen liefert die Spiral-CT mit relativ geringem Zeitaufwand wesentliche diagnostische Aussagen. Haeufig kann auf eine Angiographie verzichtet werden. Ein starres diagnostisches Stufenschema laesst sich nicht definieren. Die Thoraxuebersichtsaufnahme besitzt einen unveraendert hohen Stellenwert. (orig.)

  3. Nutrient spiraling in streams and river networks

    Science.gov (United States)

    Ensign, Scott H.; Doyle, Martin W.

    2006-12-01

    Over the past 3 decades, nutrient spiraling has become a unifying paradigm for stream biogeochemical research. This paper presents (1) a quantitative synthesis of the nutrient spiraling literature and (2) application of these data to elucidate trends in nutrient spiraling within stream networks. Results are based on 404 individual experiments on ammonium (NH4), nitrate (NO3), and phosphate (PO4) from 52 published studies. Sixty-nine percent of the experiments were performed in first- and second-order streams, and 31% were performed in third- to fifth-order streams. Uptake lengths, Sw, of NH4 (median = 86 m) and PO4 (median = 96 m) were significantly different (α = 0.05) than NO3 (median = 236 m). Areal uptake rates of NH4 (median = 28 μg m-2 min-1) were significantly different than NO3 and PO4 (median = 15 and 14 μg m-2 min-1, respectively). There were significant differences among NH4, NO3, and PO4 uptake velocity (median = 5, 1, and 2 mm min-1, respectively). Correlation analysis results were equivocal on the effect of transient storage on nutrient spiraling. Application of these data to a stream network model showed that recycling (defined here as stream length ÷ Sw) of NH4 and NO3 generally increased with stream order, while PO4 recycling remained constant along a first- to fifth-order stream gradient. Within this hypothetical stream network, cumulative NH4 uptake decreased slightly with stream order, while cumulative NO3 and PO4 uptake increased with stream order. These data suggest the importance of larger rivers to nutrient spiraling and the need to consider how stream networks affect nutrient flux between terrestrial and marine ecosystems.

  4. Utilization of the ion traps by SPIRAL

    International Nuclear Information System (INIS)

    Le Brun, C.; Lienard, E.; Mauger, F.; Tamain, B.

    1997-01-01

    An ion trap is a device capable of confine particles, ions or atoms in a well-controlled environment isolated from any exterior perturbations. There are different traps. They are utilized to collect or stock ions, to cool them after in order to subject them to high precision measurement of masses, magnetic moments, hyperfine properties, beta decay properties, etc. Some dozen of traps are currently used all over the world to study stable or radioactive ions.. SPIRAL has been designed and built to produce radioactive ions starting from various heavy ion beams. SPIRAL has the advantage that the projectile parameters, the target and the energy can be chosen to optimize the production in various regions of the nuclear chart. Also, in SPIRAL it is possible to extract more rapidly the radioactive ions formed in the targets. In addition, in SPIRAL the multicharged ion production in a ECR source is possible. The utilization of multicharged ions is indeed very useful for fast mass measurements or for the study of the interaction between the nucleus and the electronic cloud. Finally, utilization of a ion trap on SPIRAL can be designed first at the level of production target by installing a low energy output line. Than, the trap system could be up-graded and brought to its full utilization behind of the recoil spectrometer. It must be capable of selecting and slowing down the ions produced in the reactions (fusion transfer, very inelastic collisions, etc.) induced by the radioactive ions accelerated in CIME. At present, the collaboration is debating on the most favored subject to study and the most suited experimental setups. The following subjects were selected: ion capture, purification and manipulation; isomers (separation and utilization); mass measurements; hyperfine interactions; lifetimes, nuclear electric cloud; β decays; study of the N = Z nuclei close to the proton drip line; physical and chemical properties of transuranium systems

  5. Molecular clouds and galactic spiral structure

    International Nuclear Information System (INIS)

    Dame, T.M.

    1983-01-01

    Galactic CO line emission at 115 GHz has been surveyed in the region 12 0 less than or equal to l less than or equal to 60 0 and -1 0 less than or equal to b less than or equal to 1 0 in order to study the distribution of molecular clouds in the inner galaxy; an inner strip 0 0 .5 wide has been sampled every beamwidth (0 0 .125), the rest every two beamwidths. Comparison of the survey with similar HI data reveals a detailed correlation with the most intense 21-cm features, implying that the CO and HI trace the same galactic features and have the same large-scale kinematics. To each of the classical 21-cm (HI) spiral arms of the inner galaxy there corresponds a CO molecular arm which is generally more clearly defined and of higher contrast. A simple model is developed in which all of the CO emission from the inner galaxy arises from spiral arms. The modeling results suggest that molecular clouds are essentially transient objects, existing for 15 to 40 million years after their formation in a spiral arm, and are largely confined to spiral features about 300 pc wide. A variety of methods are employed to estimate distances and masses for the largest clouds detected by the inner-galaxy survey and a catalogue is compiled. The catalogued clouds, the largest of which have masses of several 10 6 M/sub sunmass/ and linear dimensions in excess of 100 pc, are found to be excellent spiral-arm tracers. One of the nearest of the clouds, that associated with the supernova remnant W44, is fully mapped in both CO and 13 CO and is discussed in detail

  6. Generation of gear tooth surfaces by application of CNC machines

    Science.gov (United States)

    Litvin, F. L.; Chen, N. X.

    1994-01-01

    This study will demonstrate the importance of application of computer numerically controlled (CNC) machines in generation of gear tooth surfaces with new topology. This topology decreases gear vibration and will extend the gear capacity and service life. A preliminary investigation by a tooth contact analysis (TCA) program has shown that gear tooth surfaces in line contact (for instance, involute helical gears with parallel axes, worm gear drives with cylindrical worms, etc.) are very sensitive to angular errors of misalignment that cause edge contact and an unfavorable shape of transmission errors and vibration. The new topology of gear tooth surfaces is based on the localization of bearing contact, and the synthesis of a predesigned parabolic function of transmission errors that is able to absorb a piecewise linear function of transmission errors caused by gear misalignment. The report will describe the following topics: description of kinematics of CNC machines with six degrees of freedom that can be applied for generation of gear tooth surfaces with new topology. A new method for grinding of gear tooth surfaces by a cone surface or surface of revolution based on application of CNC machines is described. This method provides an optimal approximation of the ground surface to the given one. This method is especially beneficial when undeveloped ruled surfaces are to be ground. Execution of motions of the CNC machine is also described. The solution to this problem can be applied as well for the transfer of machine tool settings from a conventional generator to the CNC machine. The developed theory required the derivation of a modified equation of meshing based on application of the concept of space curves, space curves represented on surfaces, geodesic curvature, surface torsion, etc. Condensed information on these topics of differential geometry is provided as well.

  7. Safe Control for Spiral Recovery of Unmanned Aerial Vehicle

    Directory of Open Access Journals (Sweden)

    Chang-Jian Ru

    2014-01-01

    Full Text Available With unmanned aerial vehicles (UAVs widely used in both military and civilian fields, many events affecting their safe flying have emerged. That UAV’s entering into the spiral is such a typical safety issue. To solve this safety problem, a novel recovery control approach is proposed. First, the factors of spiral are analyzed. Then, based on control scheduling of state variables and nonlinear dynamic inversion control laws, the spiral recovery controller is designed to accomplish guidance and control of spiral recovery. Finally, the simulation results have illustrated that the proposed control method can ensure the UAV autonomous recovery from spiral effectively.

  8. How does a planet excite multiple spiral arms?

    Science.gov (United States)

    Bae, Jaehan; Zhu, Zhaohuan

    2018-01-01

    Protoplanetary disk simulations show that a single planet excites multiple spiral arms in the background disk, potentially supported by the multi-armed spirals revealed with recent high-resolution observations in some disks. The existence of multiple spiral arms is of importance in many aspects. It is empirically found that the arm-to-arm separation increases as a function of the planetary mass, so one can use the morphology of observed spiral arms to infer the mass of unseen planets. In addition, a spiral arm opens a radial gap as it steepens into a shock, so when a planet excites multiple spiral arms it can open multiple gaps in the disk. Despite the important implications, however, the formation mechanism of multiple spiral arms has not been fully understood by far.In this talk, we explain how a planet excites multiple spiral arms. The gravitational potential of a planet can be decomposed into a Fourier series, a sum of individual azimuthal modes having different azimuthal wavenumbers. Using a linear wave theory, we first demonstrate that appropriate sets of Fourier decomposed waves can be in phase, raising a possibility that constructive interference among the waves can produce coherent structures - spiral arms. More than one spiral arm can form since such constructive interference can occur at different positions in the disk for different sets of waves. We then verify this hypothesis using a suite of two-dimensional hydrodynamic simulations. Finally, we present non-linear behavior in the formation of multiple spiral arms.

  9. Model for the local spiral structure of the galaxy

    International Nuclear Information System (INIS)

    Humphreys, R.M.

    1976-01-01

    The spatial distribution of the most luminous stars, associations, clusters, and H II regions in the region l = 270 0 to 30 0 reveal a major spiral arm, Sagittarius-Carina, which can be observed to 9 or 10 kpc from the sun in the direction l = 290 0 to 305 0 . Evidence is also presented for a spur at l = 305 0 to 310 0 on the inner side of the Saggitarius-Carina arm. The noncircular motions observed in the Carina and Sagittarius spiral features agree in both magnitude and direction and support the suggestion that Sagittarius-Carina is a major spiral arm. A model is presented for the local spiral structure with wide, massive, spiral arms which show fragmentation in our region of the Galaxy. On the basis of the optical spiral structure, the Milky Way is an Sc type spiral galaxy, perhaps of the M 101 type

  10. Mechanism of spiral formation in heterogeneous discretized excitable media.

    Science.gov (United States)

    Kinoshita, Shu-ichi; Iwamoto, Mayuko; Tateishi, Keita; Suematsu, Nobuhiko J; Ueyama, Daishin

    2013-06-01

    Spiral waves on excitable media strongly influence the functions of living systems in both a positive and negative way. The spiral formation mechanism has thus been one of the major themes in the field of reaction-diffusion systems. Although the widely believed origin of spiral waves is the interaction of traveling waves, the heterogeneity of an excitable medium has recently been suggested as a probable cause. We suggest one possible origin of spiral waves using a Belousov-Zhabotinsky reaction and a discretized FitzHugh-Nagumo model. The heterogeneity of the reaction field is shown to stochastically generate unidirectional sites, which can induce spiral waves. Furthermore, we found that the spiral wave vanished with only a small reduction in the excitability of the reaction field. These results reveal a gentle approach for controlling the appearance of a spiral wave on an excitable medium.

  11. Analysis of Pitch Gear Deterioration using Indicators

    DEFF Research Database (Denmark)

    Nielsen, Jannie Jessen; Sørensen, John Dalsgaard

    2011-01-01

    This work concerns a case study in the context of risk-based operation and maintenance of offshore wind turbines. For wind turbines with electrical pitch systems, deterioration can generally be observed at the pitch gear teeth; especially at the point where the blades are located during normal...... of the damage, and can be used for Bayesian updating of a damage model used for risk-based decision making. For this decision problem, the risk of failure should be compared to the cost of preventive maintenance. The hypothesis that the maximum pitch motor torque is an indicator of the damage size is supported...... changes in the temperature are the primary cause of the decrease. A model is established to remove the effect of the explained variation, and it is investigated if deterioration can be detected as changes in the peak torque. A small increase could be detected after the maintenance, but before...

  12. Investigating Vibration Properties of a Planetary Gear Set with a Cracked Tooth in a Planet Gear

    Science.gov (United States)

    2014-12-23

    sidebands appear at mfm±nfplanet± kfc or mfm±nfplanet±kfp, where m, n and k are all integers; fp represents rotation frequency of the planet gear and...region from 43 fm to 45 fm. Sidebands are not symmetric and sizable sidebands located at mfm±nfplanet± kfc or mfm±nfplanet±kfp, where m, n and k are

  13. The design and analysis of single flank transmission error testor for loaded gears

    Science.gov (United States)

    Houser, D. R.; Bassett, D. E.

    1985-01-01

    Due to geometrical imperfections in gears and finite tooth stiffnesses, the motion transmitted from an input gear shaft to an output gear shaft will not have conjugate action. In order to strengthen the understanding of transmission error and to verify mathematical models of gear transmission error, a test stand that will measure the transmission error of a gear pair at operating loads, but at reduced speeds would be desirable. This document describes the design and development of a loaded transmission error tester. For a gear box with a gear ratio of one, few tooth meshing combinations will occur during a single test. In order to observe the effects of different tooth mesh combinations and to increase the ability to load test gear pairs with higher gear ratios, the system was designed around a gear box with a gear ratio of two.

  14. Two dimensional model of a permanent magnet spur gear

    DEFF Research Database (Denmark)

    Jørgensen, Frank Thorleif; Andersen, Torben Ole; Rasmussen, Peter Omand

    2005-01-01

    This paper presents calculation and measurement results of a high-performance permanent-magnetic gear. The analyzed permanent-magnetic gear has a gear ratio of 5.5 and is able to deliver 27 N/spl middot/m. The analysis has shown that special attention needs to be paid to the system where the gear...... is to be installed because of a low natural torsion spring constant. The analyzed gear was also constructed in practice in order to validate the analysis and predict the efficiency. The measured torque from the magnetic gear was only 16 N/spl middot/m reduced by the large end-effects. A systematic analysis...... of the loss components in the magnetic gear is also performed in order to figure out why the efficiency for the actual construction was only 81%. A large magnetic loss component originated in the bearings, where an unplanned extra bearing was necessary due to mechanical problems. Without the losses...

  15. Hybrid Gear Performance Under Loss-of-Lubrication Conditions

    Science.gov (United States)

    Laberge, Kelsen E.; Berkebile, Stephen P.; Handschuh, Robert F.; Roberts, Gary D.

    2017-01-01

    Hybrid composite gear technology is being investigated to increase power density in rotorcraft drive systems. These gears differ from conventional steel gears in that the structural web material is replaced with a lightweight carbon fiber composite. Past studies have focused on performance of this technology under normal operating conditions, however, for this technology to be viable it must also withstand adverse conditions. The study presented here evaluates the performance of hybrid gears under loss-of-lubrication conditions in NASA Glenn Research Centers Contact Fatigue Test Facility. Two experiments are presented using small-scale 3.5 inch (8.9 cm) pitch diameter hybrid gears and compared to a baseline steel gear pair. Results of these tests show that there are limitations to the use of a hexagonal interlock pattern between the steel and composite. There is also evidence that the presence of polymer in the gear during an oil out event has a potential to increase time to failure. Further studies are planned to expand on these initial findings.

  16. Evaluation of Gear Condition Indicator Performance on Rotorcraft Fleet

    Science.gov (United States)

    Antolick, Lance J.; Branning, Jeremy S.; Wade, Daniel R.; Dempsey, Paula J.

    2010-01-01

    The U.S. Army is currently expanding its fleet of Health Usage Monitoring Systems (HUMS) equipped aircraft at significant rates, to now include over 1,000 rotorcraft. Two different on-board HUMS, the Honeywell Modern Signal Processing Unit (MSPU) and the Goodrich Integrated Vehicle Health Management System (IVHMS), are collecting vibration health data on aircraft that include the Apache, Blackhawk, Chinook, and Kiowa Warrior. The objective of this paper is to recommend the most effective gear condition indicators for fleet use based on both a theoretical foundation and field data. Gear diagnostics with better performance will be recommended based on both a theoretical foundation and results of in-fleet use. In order to evaluate the gear condition indicator performance on rotorcraft fleets, results of more than five years of health monitoring for gear faults in the entire HUMS equipped Army helicopter fleet will be presented. More than ten examples of gear faults indicated by the gear CI have been compiled and each reviewed for accuracy. False alarms indications will also be discussed. Performance data from test rigs and seeded fault tests will also be presented. The results of the fleet analysis will be discussed, and a performance metric assigned to each of the competing algorithms. Gear fault diagnostic algorithms that are compliant with ADS-79A will be recommended for future use and development. The performance of gear algorithms used in the commercial units and the effectiveness of the gear CI as a fault identifier will be assessed using the criteria outlined in the standards in ADS-79A-HDBK, an Army handbook that outlines the conversion from Reliability Centered Maintenance to the On-Condition status of Condition Based Maintenance.

  17. Radial distributions of arm-gas offsets as an observational test of spiral theories

    OpenAIRE

    Baba, Junichi; Morokuma-Matsui, Kana; Egusa, Fumi

    2015-01-01

    Theories of stellar spiral arms in disk galaxies can be grouped into two classes based on the longevity of a spiral arm. Although the quasi-stationary density wave theory supposes that spirals are rigidly-rotating, long-lived patterns, the dynamic spiral theory predicts that spirals are differentially-rotating, transient, recurrent patterns. In order to distinguish between the two spiral models from observations, we performed hydrodynamic simulations with steady and dynamic spiral models. Hyd...

  18. Technology Innovation of Power Transmission Gearing in Aviation

    Science.gov (United States)

    Handschuh, Robert F.

    2009-01-01

    An overview of rotary wing evolution and innovations over the last 20 years was presented. This overview is provided from a drive system perspective. Examples of technology innovations that have changed and advanced drive systems of rotary wing vehicles will be provided. These innovations include full 6-axis CNC gear manufacture, face gear development to aerospace standards, health and usage monitoring, and gear geometry and bearing improvements. Also, an overview of current state-of-the-art activities being conducted at NASA Glenn is presented with a short look to fixed and rotary wing aircraft and systems needed for the future.

  19. Multi-stage internal gear/turbine fuel pump

    Energy Technology Data Exchange (ETDEWEB)

    Maier, Eugen; Raney, Michael Raymond

    2004-07-06

    A multi-stage internal gear/turbine fuel pump for a vehicle includes a housing having an inlet and an outlet and a motor disposed in the housing. The multi-stage internal gear/turbine fuel pump also includes a shaft extending axially and disposed in the housing. The multi-stage internal gear/turbine fuel pump further includes a plurality of pumping modules disposed axially along the shaft. One of the pumping modules is a turbine pumping module and another of the pumping modules is a gerotor pumping module for rotation by the motor to pump fuel from the inlet to the outlet.

  20. ARTIFICIAL NEURAL NETWORKS BASED GEARS MATERIAL SELECTION HYBRID INTELLIGENT SYSTEM

    Institute of Scientific and Technical Information of China (English)

    X.C. Li; W.X. Zhu; G. Chen; D.S. Mei; J. Zhang; K.M. Chen

    2003-01-01

    An artificial neural networks(ANNs) based gear material selection hybrid intelligent system is established by analyzing the individual advantages and weakness of expert system (ES) and ANNs and the applications in material select of them. The system mainly consists of tow parts: ES and ANNs. By being trained with much data samples,the back propagation (BP) ANN gets the knowledge of gear materials selection, and is able to inference according to user input. The system realizes the complementing of ANNs and ES. Using this system, engineers without materials selection experience can conveniently deal with gear materials selection.

  1. A MATHEMATICAL MODEL OF CHP 2000 TYPE PROGRESSIVE GEAR

    Directory of Open Access Journals (Sweden)

    Paweł Lonkwic

    2016-12-01

    Full Text Available The project of CHP2000 type progressive gear has been presented in the article. The offered solution from its construction point of view differs from the existing solutions due to the application of Belleville springs packets supporting the braking roller cam and achieving a flexible range of the gear loading. The standard concept of the gear loading within a mathematical and a geometrical model has been presented in the article. The proposed solution can be used in the friction lifts with the loading capacity from 8500 up to 20000 N.

  2. Engagement of Metal Debris into a Gear Mesh

    Science.gov (United States)

    Handschuh, Robert F.; Krantz, Timothy L.

    2010-01-01

    A series of bench top experiments was conducted to determine the effects of metallic debris being dragged through meshing gear teeth. A test rig that is typically used to conduct contact fatigue experiments was used for these tests. Several sizes of drill material, shim stock, and pieces of gear teeth were introduced and then driven through the meshing region. The level of torque required to drive the "chip" through the gear mesh was measured. From the data gathered, chip size sufficient to jam the mechanism can be determined.

  3. Natural Characteristics of The Herringbone Gear Transmission System

    Science.gov (United States)

    Zhou, Jianxing; Sun, Wenlei; Cao, Li

    2018-03-01

    According to the structure characteristics of herringbone gear transmission, a more realistic dynamic model of the transmission system is built in consideration of the inner excitation, herringbone gears axial positioning and sliding bearing etc. The natural frequencies of the system are calculated, and the vibration mode is divided into symmetric vibration modes and asymmetric vibration modes. The time history of system dynamic force is obtained by solving the dynamic model. The effects of the connection stiffness of left and right sides of herringbone gears and axial support stiffness on natural characteristics are discussed.

  4. Spiral optical designs for nonimaging applications

    Science.gov (United States)

    Zamora, Pablo; Benítez, Pablo; Miñano, Juan C.; Vilaplana, Juan; Buljan, Marina

    2011-10-01

    Manufacturing technologies as injection molding or embossing specify their production limits for minimum radii of the vertices or draft angle for demolding, for instance. In some demanding nonimaging applications, these restrictions may limit the system optical efficiency or affect the generation of undesired artifacts on the illumination pattern. A novel manufacturing concept is presented here, in which the optical surfaces are not obtained from the usual revolution symmetry with respect to a central axis (z axis), but they are calculated as free-form surfaces describing a spiral trajectory around z axis. The main advantage of this new concept lies in the manufacturing process: a molded piece can be easily separated from its mold just by applying a combination of rotational movement around axis z and linear movement along axis z, even for negative draft angles. Some of these spiral symmetry examples will be shown here, as well as their simulated results.

  5. Diagnosing extracranial atherosclerotic diseases with spiral CT

    International Nuclear Information System (INIS)

    Moran, C.J.; Vannier, M.W.; Erickson, K.K.; Broderick, D.F.; Kido, D.K.; Yoffie, R.L.

    1991-01-01

    This paper reports that this discovery study was performed to determine whether extracranial carotid artery plaques could be diagnosed with a new CT technique (spiral CT) that allows nondistorted three-dimensional (3D) reconstructions in the z axis. Twenty carotid arteries were examined with spiral CT in normal volunteers and in patients suspected of having atherosclerotic plaques in the extracranial carotid arteries. The Somatom Plus CT table was advanced at a constant rate, the x-ray tube was continuously rotated, and 3D data were continuously acquired. Sixty milliliters of nonionic contrast medium was injected intravenously previous to and during the acquisition of data. The carotid bifurcations were identified in all patients. Planar images, similar to conventional intraarterial angiograms, were routinely produced from the volumetric CT data

  6. Status of the SPIRAL2 injector commissioning

    Energy Technology Data Exchange (ETDEWEB)

    Thuillier, T., E-mail: thuillier@lpsc.in2p3.fr; Angot, J.; Jacob, J.; Lamy, T.; Sole, P. [LPSC, Université Grenoble Alpes, CNRS/IN2P3, 53 rue des Martyrs, 38026 Grenoble Cedex (France); Barué, C.; Bertrand, P.; Canet, C.; Ferdinand, R.; Flambard, J.-L.; Jardin, P.; Lemagnen, F.; Maunoury, L.; Osmond, B. [GANIL, CNRS/IN2P3, Bvd Henri Becquerel, BP 55027, 14076 Caen Cedex 5 (France); Biarrotte, J. L. [IPN Orsay, Université Paris Sud, CNRS/IN2P3, 15 rue Georges Clémenceau, 91406 Orsay Cedex (France); Denis, J.-F.; Roger, A.; Touzery, R.; Tuske, O.; Uriot, D. [Irfu, CEA Saclay, DSM/Irfu/SACM, 91191 Gif Sur Yvette (France); and others

    2016-02-15

    The SPIRAL2 injector, installed in its tunnel, is currently under commissioning at GANIL, Caen, France. The injector is composed of two low energy beam transport lines: one is dedicated to the light ion beam production, the other to the heavy ions. The first light ion beam, created by a 2.45 GHz electron cyclotron resonance ion source, has been successfully produced in December 2014. The first beam of the PHOENIX V2 18 GHz heavy ion source was analyzed on 10 July 2015. A status of the SPIRAL2 injector commissioning is given. An upgrade of the heavy ion source, named PHOENIX V3 aimed to replace the V2, is presented. The new version features a doubled plasma chamber volume and the high charge state beam intensity is expected to increase by a factor of 1.5 to 2 up to the mass ∼50. A status of its assembly is proposed.

  7. Rolling motions in an inner spiral arm

    International Nuclear Information System (INIS)

    Strauss, F.M.; Poeppel, W.

    1976-01-01

    Hydrogen line observations made at low galactic latitudes for l=318degree, 326degree, 334degree, and 337degree show the presence of velocity gradients in latitude in the nearest inner spiral arm, similar to those found by other observations in different regions. Maximum velocity change is about 10 km s -1 for l=337degree. By generating synthetic line profiles constructed from a model spiral arm, several possible causes of these ''rolling motions'' were studied, such as a vertical displacement or a tilt of the arm (which failed to account for the observations) and rotation or shearing in the arm. It was futher shown that a typical arm can maintain such a motion (approx. =75 km s -1 kpc -1 ) with its own gravitational potential. The results are used to study the origin and tilt of Gould's Belt

  8. Stationary spiral flow in polytropic stellar models

    Science.gov (United States)

    Pekeris, C. L.

    1980-01-01

    It is shown that, in addition to the static Emden solution, a self-gravitating polytropic gas has a dynamic option in which there is stationary flow along spiral trajectories wound around the surfaces of concentric tori. The motion is obtained as a solution of a partial differential equation which is satisfied by the meridional stream function, coupled with Poisson's equation and a Bernoulli-type equation for the pressure (density). The pressure is affected by the whole of the Bernoulli term rather than by the centrifugal part only, which acts for a rotating model, and it may be reduced down to zero at the center. The spiral type of flow is illustrated for an incompressible fluid (n = 0), for which an exact solution is obtained. The features of the dynamic constant-density model are discussed as a basis for future comparison with the solution for compressible models. PMID:16592825

  9. Gastric spiral bacteria in small felids.

    Science.gov (United States)

    Kinsel, M J; Kovarik, P; Murnane, R D

    1998-06-01

    Nine small cats, including one bobcat (Felis rufus), one Pallas cat (F. manul), one Canada lynx (F. lynx canadensis), two fishing cats (F. viverrina), two margays (F. wiedii), and two sand cats (F. margarita), necropsied between June 1995 and March 1997 had large numbers of gastric spiral bacteria, whereas five large cats, including one African lion (Panthera leo), two snow leopards (P. uncia), one Siberian tiger (P. tigris altaica), and one jaguar (P. onca), necropsied during the same period had none. All of the spiral organisms from the nine small cats were histologically and ultrastructurally similar. Histologically, the spiral bacteria were 5-14 microm long with five to nine coils per organism and were located both extracellularly within gastric glands and surface mucus, and intracellularly in parietal cells. Spiral bacteria in gastric mucosal scrapings from the Canada lynx, one fishing cat, and the two sand cats were gram negative and had corkscrewlike to tumbling motility when viewed with phase contrast microscopy. The bacteria were 0.5-0.7 microm wide, with a periodicity of 0.65-1.1 microm in all cats. Bipolar sheathed flagella were occasionally observed, and no periplasmic fibrils were seen. The bacteria were extracellular in parietal cell canaliculi and intracellular within parietal cells. Culture of mucosal scrapings from the Canada lynx and sand cats was unsuccessful. Based on morphology, motility, and cellular tropism, the bacteria were probably Helicobacter-like organisms. Although the two margays had moderate lymphoplasmacytic gastritis, the other cats lacked or had only mild gastric lymphoid infiltrates, suggesting that these organisms are either commensals or opportunistic pathogens.

  10. Star distribution in the Orion spiral arm

    International Nuclear Information System (INIS)

    Basharina, T.S.; Pavlovskaya, E.D.; Filippova, A.A.

    1985-01-01

    The structure of the Orion spiral arm is studied by numerical experiments, assuming that in each direction considered the star distribution along the line of sight is a combination of two Gaussian laws. The corresponding parameters are evaluated for four Milky Way fields; the bimodal laws now fit the observations by the chi 2 criterion. In the Orion arm the line-of-sight star densities follow asymmetric curves, steeper at the outer edge of the arm

  11. The surface brightness of spiral galaxies

    International Nuclear Information System (INIS)

    Phillipps, S.; Disney, M.

    1983-01-01

    It is proposed that Freeman's discovery that the extrapolated central surface brightness of spiral galaxies is approximately constant can be simply explained if the galaxies contain a spheroidal component which dominates the light in their outer isophotes. Calculations of an effective central surface brightness indicate a wide spread of values. This requires either a wide spread in disc properties or significant spheroidal components or, most probably, both. (author)

  12. A Fermat's spiral multifilament-core fiber

    Science.gov (United States)

    Tartara, L.; Codemard, C.

    2013-02-01

    A multifilament-core optical fiber where the microstructure is arranged in a Fermat's spiral is presented. The properties of such a fiber to be exploited for laser light amplification are numerically investigated by means of a full-vectorial finite-element method. Thanks to this peculiar microstructure, the fiber is shown to have an increased Brillouin threshold power and very low bending losses, while preserving a very good beam spatial quality.

  13. Spiral-arm instability: giant clump formation via fragmentation of a galactic spiral arm

    Science.gov (United States)

    Inoue, Shigeki; Yoshida, Naoki

    2018-03-01

    Fragmentation of a spiral arm is thought to drive the formation of giant clumps in galaxies. Using linear perturbation analysis for self-gravitating spiral arms, we derive an instability parameter and define the conditions for clump formation. We extend our analysis to multicomponent systems that consist of gas and stars in an external potential. We then perform numerical simulations of isolated disc galaxies with isothermal gas, and compare the results with the prediction of our analytic model. Our model describes accurately the evolution of the spiral arms in our simulations, even when spiral arms dynamically interact with one another. We show that most of the giant clumps formed in the simulated disc galaxies satisfy the instability condition. The clump masses predicted by our model are in agreement with the simulation results, but the growth time-scale of unstable perturbations is overestimated by a factor of a few. We also apply our instability analysis to derive scaling relations of clump properties. The expected scaling relation between the clump size, velocity dispersion, and circular velocity is slightly different from that given by the Toomre instability analyses, but neither is inconsistent with currently available observations. We argue that the spiral-arm instability is a viable formation mechanism of giant clumps in gas-rich disc galaxies.

  14. Rigid MATLAB drivetrain model of a 500 kW wind turbine for predicting maximum gear tooth stresses in a planetary gearbox using multibody gear constraints

    DEFF Research Database (Denmark)

    Jørgensen, Martin Felix; Pedersen, Niels Leergaard; Sørensen, Jens Nørkær

    2014-01-01

    multiple planetary gears are not taken into account. Finite Element Method (FEM) calculations show that when the wind turbine runs close to the maximum wind speed, the maximum gear tooth stress is in the range of 500–700 MPa, which is considered to be realistic using a “worst-case” method. The presented...... for not only transferring torque but also for calculating the gear tooth and internal body reaction forces. The method is appropriate for predicting gear tooth stresses without considering all the complexity of gear tooth geometries. This means that, e.g. gear tooth load-sharing and load-distribution among...

  15. Incorporating hydrologic variability into nutrient spiraling

    Science.gov (United States)

    Doyle, Martin W.

    2005-09-01

    Nutrient spiraling describes the path of a nutrient molecule within a stream ecosystem, combining the biochemical cycling processes with the downstream driving force of stream discharge. To date, nutrient spiraling approaches have been hampered by their inability to deal with fluctuating flows, as most studies have characterized nutrient retention within only a small range of discharges near base flow. Here hydrologic variability is incorporated into nutrient spiraling theory by drawing on the fluvial geomorphic concept of effective discharge. The effective discharge for nutrient retention is proposed to be that discharge which, over long periods of time, is responsible for the greatest portion of nutrient retention. A developed analytical model predicts that the effective discharge for nutrient retention will equal the modal discharge for small streams or those with little discharge variability. As modal discharge increases or discharge variability increases, the effective discharge becomes increasingly less than the modal discharge. In addition to the effective discharge, a new metric is proposed, the functionally equivalent discharge, which is the single discharge that will reproduce the magnitude of nutrient retention generated by the full hydrologic frequency distribution when all discharge takes place at that rate. The functionally equivalent discharge was found to be the same as the modal discharge at low hydrologic variability, but increasingly different from the modal discharge at large hydrologic variability. The functionally equivalent discharge provides a simple quantitative means of incorporating hydrologic variability into long-term nutrient budgets.

  16. Rarefied, rotational gas flows in spiral galaxies

    International Nuclear Information System (INIS)

    Roberts, W.W. Jr.; Hausman, M.A.

    1983-01-01

    We develop a computational model of a rotating, rarefied gas in which the individual molecules collide inelastically and are subject to circularly asymmetric external forces and internal heating sources. This model is applied to the interstellar medium (ISM) of spiral galaxies, in which most of the matter is confined to discrete gas clouds separated by a tenuous intercloud medium. We identify inelastically-colliding gas molecules with interstellar clouds which orbit ballistically in the galactic gravitational field and are perturbed by expanding shells surrounding supernovae. When a small, spiral perturbation is added to the gravitational force to mimic a spiral galaxy, the cloud distribution responds with a strong, global shock. In the model, stars are formed from the gas when clouds collide or are perturbed by supernovae; these stars are the internal heating sources for the gas cloud system. We determine the morphologies (evolution, distribution) of the two components, gas and stars, in the model as functions of varying input physics. Variation of the cloud system's collisional mean free path (over physically-realistic ranges) has remarkably little influence on the computed shock structure

  17. The 1+/n+ solution for SPIRAL ?

    International Nuclear Information System (INIS)

    Villari, A.C.C.; Bruandet, J.S.; Chauvin, N.; Curdy, J.C.; Gaubert, G.; Lamy, T.; Maunoury, L.; Sole, J.P.; Sortais, P.; Vieux-Rochaz, J.L.

    1997-01-01

    The use of a primary ion source for the production of 1+ ions in the production cave of SPIRAL with subsequent injection in an ECRIS (Electron Cyclotron Resonance Ion Source) for charge multiplication is discussed. The first results obtained at ISN Grenoble for the production of Rb (9+) and Ar (8+) stable beams are presented. The overall efficiency of this system for the production of the Ar beams is compared with the present situation where the ECRIS is placed inside the cave of SPIRAL. An important gain in the reliability and reduction of functioning costs would be obtained in the case of the implementation of the 1+/n+ mode in the SPIRAL project at GANIL. A reduction of overall efficiency of a factor 1.5 to 3 with respect to the present NANOGAN-II ensemble is expected for light noble gas radioactive ion beams. This factor can be reduced depending on the choice of the ECRIS for a particular multicharged ion production. Finally, important R and D is needed for extending the range of elements to be produced in the 1+/n+ mode and to define 'good' ion sources with small energy dispersion for 1+ production. (authors)

  18. 49 CFR 230.90 - Draw gear between steam locomotive and tender.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Draw gear between steam locomotive and tender. 230... Steam Locomotives and Tenders Draw Gear and Draft Systems § 230.90 Draw gear between steam locomotive and tender. (a) Maintenance and testing. The draw gear between the steam locomotive and tender...

  19. 50 CFR 660.319 - Open access fishery gear identification and marking.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Open access fishery gear identification... COAST STATES West Coast Groundfish-Open Access Fisheries § 660.319 Open access fishery gear identification and marking. (a) Gear identification. (1) Open access fixed gear (longline, trap or pot, set net...

  20. 75 FR 12462 - Fisheries of the Northeastern United States; Northeast Multispecies Fishery; Removal of Gear...

    Science.gov (United States)

    2010-03-16

    ...; Removal of Gear Restriction for the U.S./Canada Management Area AGENCY: National Marine Fisheries Service...; removal of gear restrictions. SUMMARY: This action removes temporary gear restrictions in both the Eastern... Management Act (Magnuson- Stevens Act). DATES: Removal of the temporary gear restriction in the Western U.S...

  1. 46 CFR 97.37-33 - Instructions for changing steering gear.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Instructions for changing steering gear. 97.37-33... steering gear. (a) Instructions in at least 1/2 inch letters and figures shall be posted in the steering... gear. Each clutch, gear, wheel, lever, valve, or switch which is used during the changeover shall be...

  2. 46 CFR 58.25-10 - Main and auxiliary steering gear.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Main and auxiliary steering gear. 58.25-10 Section 58.25... AUXILIARY MACHINERY AND RELATED SYSTEMS Steering Gear § 58.25-10 Main and auxiliary steering gear. (a) Power-operated main and auxiliary steering gear must be separate systems that are independent throughout their...

  3. 50 CFR Table 19 to Part 679 - Seabird Avoidance Gear Codes

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Seabird Avoidance Gear Codes 19 Table 19... ALASKA Pt. 679, Table 19 Table 19 to Part 679—Seabird Avoidance Gear Codes VESSEL LOGBOOK CODE SEABIRD AVOIDANCE GEAR OR METHOD. 1 Paired Streamer Lines: Used during deployment of hook-and-line gear to prevent...

  4. Transitions between Taylor vortices and spirals via wavy Taylor vortices and wavy spirals

    International Nuclear Information System (INIS)

    Hoffmann, Ch; Altmeyer, S; Pinter, A; Luecke, M

    2009-01-01

    We present numerical simulations of closed wavy Taylor vortices and of helicoidal wavy spirals in the Taylor-Couette system. These wavy structures appearing via a secondary bifurcation out of Taylor vortex flow and out of spiral vortex flow, respectively, mediate transitions between Taylor and spiral vortices and vice versa. Structure, dynamics, stability and bifurcation behaviour are investigated in quantitative detail as a function of Reynolds numbers and wave numbers for counter-rotating as well as corotating cylinders. These results are obtained by solving the Navier-Stokes equations subject to axial periodicity for a radius ratio η=0.5 with a combination of a finite differences method and a Galerkin method.

  5. Stress analyses of pump gears produced by powder metallurgy

    Energy Technology Data Exchange (ETDEWEB)

    Cetinel, Hakan [Celal Bayar Univ., Mechanical Engineering Dept. (Turkey); Yilmaz, Burak

    2013-06-01

    In this study, trochoidal type (gerotor) hydraulic pump gears were produced by powder metallurgy (P/M) technique. Several gears with different mechanical properties have been obtained by changing process variables. The tooth contact stresses were calculated analytically under particular operation conditions of the hydraulic pump. The 3D models have been obtained from real gears by using Capability Maturity Model (CMM, 3D scanning) operation and SOLIDWORKS software. Stress analyses were conducted on these 3D models by using ANSYS WORKBENCH software. It was found that the density increases by the increase of sintering duration and mechanical properties were positively affected by the increase of density. Maximum deformation takes place in the region of the outer gear where failure generally occurs with the minimum cross-section area.

  6. 29 CFR 1915.116 - Use of gear.

    Science.gov (United States)

    2010-07-01

    ... manually or by a crane, winch, hoist, or derrick, shall be completely opened. The beam or pontoon left in... employees are in the square of the hatch below. (p) Before loads or empty lifting gear are raised, lowered...

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  8. Teaching Planetary Gear Trains with the Aid of Nomographs

    Directory of Open Access Journals (Sweden)

    Essam Lauibi Esmail

    2013-01-01

    Full Text Available Planetary gear trains (PGTs are introduced to undergraduate mechanical engineering students in the course of Theory of Machines. The complexity of the traditional methods for analyzing PGTs has kept many from becoming familiar with the capability of PGTs in mechanisms and machine design. In this paper a unified general formulation for simultaneously visualizing velocities, torques, and power flow through a train is presented on a single nomograph. Therefore, the increasing complex mechanical systems, such as automotive transmissions, are much easier to understand. Nomographs of Fundamental Gear Entities (FGEs are constructed based on the nomographs of their fundamental circuits, without specifying the exact gear dimensions. They are then unified in one system nomograph. Nomographs are promising to provide designers with an efficient tool for the design of geared mechanisms.

  9. OPTIMIZATION OF HEATING OF GEAR WHEEL USING NUMERICAL MODELING

    Directory of Open Access Journals (Sweden)

    Soňa Benešová

    2013-09-01

    Full Text Available Successful heat treating and carburizing of gear wheels for wind turbine gear boxes requires that plastic deformation in the wheel is minimized. Numerical modeling using the DEFORM software was aimed at exploring the effects of the base, on which the gear wheel rests during heating, on the heating process. Homogeneous heating was assumed. It was found that the base heats up more quickly than the workpiece. It is the consequence of the base's shape and volume. As a result, the base expands and slides against the wheel, predominantly at the first heating stage. Later on, it prevents the gear wheel from expanding, causing plastic deformation in the wheel. The findings were used for designing new heating schedules to minimize these undesirable interactions and to reduce the plastic deformation to a negligible magnitude. In addition, this paper presents an example of a practical use of numerical modeling in the DEFORM software.

  10. OPTIMIZATION OF HEATING OF GEAR WHEEL USING NUMERICAL MODELING

    Directory of Open Access Journals (Sweden)

    Sona Benesova

    2013-05-01

    Full Text Available Successful heat treating and carburizing of gear wheels for wind turbine gear boxes requires that plastic deformation in the wheel is minimized. Numerical modeling using the DEFORM software was aimed at exploring the effects of the base, on which the gear wheel rests during heating, on the heating process. Homogeneous heating was assumed. It was found that the base heats up more quickly than the workpiece. It is the consequence of the base's shape and volume. As a result, the base expands and slides against the wheel, predominantly at the first heating stage. Later on, it prevents the gear wheel from expanding, causing plastic deformation in the wheel. The findings were used for designing new heating schedules to minimize these undesirable interactions and to reduce the plastic deformation to a negligible magnitude. In addition, this paper presents an example of a practical use of numerical modeling in the DEFORM software.

  11. Toothed gear pumps for special applications; Zahnradpumpen fuer Sonderanwendungen

    Energy Technology Data Exchange (ETDEWEB)

    Kremer, H. [WITTE PUMPS und TECHNOLOGY GmbH, Uetersen (Germany)

    2007-07-01

    Gear pumps are utilized in a big variety of industrial processes. This essay discusses the typical applications gear pumps are used for. Based on the general function of gear pumps the technical features of these different pump types are pointed out. The process parameters have been more or less the same for the last decades. Nowadays a higher demand regarding pressures and temperatures, sometimes even a combination of both, can be observed. This development is the challenge to go for special constructions and new materials. The range of applications is extended step by step, always aware of the fact, that these gear pumps are often operating at their specific limits. Finally some examples right from the plant give an overview over this development. (orig.)

  12. Characteristics study of the gears by the CAD/CAE

    Science.gov (United States)

    Wang, P. Y.; Chang, S. L.; Lee, B. Y.; Nguyen, D. H.; Cao, C. W.

    2017-09-01

    Gears are the most important transmission component in machines. The rapid development of the machines in industry requires a shorter time of the analysis process. In traditional, the gears are analyzed by setting up the complete mathematical model firstly, considering the profile of cutter and coordinate systems relationship between the machine and the cutter. It is a really complex and time-consuming process. Recently, the CAD/CAE software is well developed and useful in the mechanical design. In this paper, the Autodesk Inventor® software is introduced to model the spherical gears firstly, and then the models can also be transferred into ANSYS Workbench for the finite element analysis. The proposed process in this paper is helpful to the engineers to speed up the analyzing process of gears in the design stage.

  13. Experimental Research on Vibrations of Double Harmonic Gear Transmission

    Directory of Open Access Journals (Sweden)

    Sava Ianici

    2017-11-01

    Full Text Available Gears transmission can be important sources of vibration in the mechanical system structures and can have a significant share in the overall vibration level. The current trend of significant increase in powers and speeds transmitted by modern mechanical systems, along with the size reduction, may cause a worsening of the behaviour of transmissions with gears in terms of vibration, especially when the optimization criteria were not respected in the design, execution and installation phase. This paper presents a study of vibrations that occur in a double harmonic gear transmission (DHGT, based on experimental research. The experimental researches revealed that in a double harmonic gear transmission the vibrations are initiated and develop in the multipara harmonics engagement of the teeth and in the kinematic couplings materialized between the wave generator and the flexible toothed wheel. These vibrations are later transmitted by means of the shafts and bearings to the transmission housing, respectively, through the walls of it, propagating in the air.

  14. Feedforward Control of Gear Mesh Vibration Using Piezoelectric Actuators

    Directory of Open Access Journals (Sweden)

    Gerald T. Montague

    1994-01-01

    Full Text Available This article presents a novel means for suppressing gear mesh related vibrations. The key components in this approach are piezoelectric actuators and a high-frequency, analog feed forward controller. Test results are presented and show up to a 70% reduction in gear mesh acceleration and vibration control up to 4500 Hz. The principle of the approach is explained by an analysis of a harmonically excited, general linear vibratory system.

  15. Darwin-industrien i højt gear

    DEFF Research Database (Denmark)

    Kjærgaard, Peter C.

    2008-01-01

    Darwin-industrien i højt gear. Næste år bliver et 'Darwin-år' - både tilhængere og kritikere gør sig klar. Udgivelsesdato: 12. december......Darwin-industrien i højt gear. Næste år bliver et 'Darwin-år' - både tilhængere og kritikere gør sig klar. Udgivelsesdato: 12. december...

  16. Investigation of the paired-gear method in selectivity studies

    DEFF Research Database (Denmark)

    Sistiaga, Manu; Herrmann, Bent; Larsen, R.B.

    2009-01-01

    was repeated throughout the eight cases in this investigation. When using the paired-gear method, the distribution of the estimated L50 and SR is wider; the distribution of the estimated split parameter has a higher variability than the true split; the estimated mean L50 and SR can be biased; the estimated...... recommend that the methodology used to obtain selectivity estimates using the paired-gear method be reviewed....

  17. Ablation acceleration of macroparticle in spiral magnetic fields

    International Nuclear Information System (INIS)

    Ikuta, Kazunari.

    1981-05-01

    The rocket motion of macroparticles heated by energetic pulses in a spiral magnetic field was studied. The purpose of the present work is to study the ablation acceleration of a macroparticle in a spiral magnetic field with the help of the law of conservation of angular momentum. The basic equation of motion of ablatively accelerated projectile in a spiral magnetic field was derived. Any rocket which is ejecting fully ionized plasma in an intense magnetic field with rotational transform is able to have spin by the law of conservation of momentum. The effect of spiral magnetic field on macroparticle acceleration is discussed. The necessary mass ratio increase exponentially with respect to the field parameter. The spiral field should be employed with care to have only to stabilize the position of macroparticles. As conclusion, it can be said that the ablation acceleration of the projectile in a spiral field can give the accelerated body spin quite easily. (Kato, T.)

  18. Mechanical response of spiral interconnect arrays for highly stretchable electronics

    KAUST Repository

    Qaiser, Nadeem

    2017-11-21

    A spiral interconnect array is a commonly used architecture for stretchable electronics, which accommodates large deformations during stretching. Here, we show the effect of different geometrical morphologies on the deformation behavior of the spiral island network. We use numerical modeling to calculate the stresses and strains in the spiral interconnects under the prescribed displacement of 1000 μm. Our result shows that spiral arm elongation depends on the angular position of that particular spiral in the array. We also introduce the concept of a unit-cell, which fairly replicates the deformation mechanism for full complex hexagon, diamond, and square shaped arrays. The spiral interconnects which are axially connected between displaced and fixed islands attain higher stretchability and thus experience the maximum deformations. We perform tensile testing of 3D printed replica and find that experimental observations corroborate with theoretical study.

  19. Optical and theoretical studies of giant clouds in spiral galaxies

    International Nuclear Information System (INIS)

    Elmegreen, B.G.; Elmegreen, D.M.

    1980-01-01

    An optical study of four spiral galaxies, combined with radiative transfer models for transmitted and scattered light, has led to a determination of the opacities and masses of numerous dark patches and dust lanes that outline spiral structure. The observed compression factors for the spiral-like dust lanes are in accord with expectations from the theory of gas flow in spiral density waves. Several low density (10 2 cm -3 ) clouds containing 10 6 to 10 7 solar masses were also studied. These results are discussed in terms of recent theoretical models of cloud and star formation in spiral galaxies. The long-term evolution of giant molecular clouds is shown to have important consequences for the positions and ages of star formation sites in spiral arms. (Auth.)

  20. Wave-particle dualism of spiral waves dynamics.

    Science.gov (United States)

    Biktasheva, I V; Biktashev, V N

    2003-02-01

    We demonstrate and explain a wave-particle dualism of such classical macroscopic phenomena as spiral waves in active media. That means although spiral waves appear as nonlocal processes involving the whole medium, they respond to small perturbations as effectively localized entities. The dualism appears as an emergent property of a nonlinear field and is mathematically expressed in terms of the spiral waves response functions, which are essentially nonzero only in the vicinity of the spiral wave core. Knowledge of the response functions allows quantitatively accurate prediction of the spiral wave drift due to small perturbations of any nature, which makes them as fundamental characteristics for spiral waves as mass is for the condensed matter.

  1. Mechanical response of spiral interconnect arrays for highly stretchable electronics

    KAUST Repository

    Qaiser, Nadeem; Khan, S. M.; Nour, Maha A.; Rehman, M. U.; Rojas, J. P.; Hussain, Muhammad Mustafa

    2017-01-01

    A spiral interconnect array is a commonly used architecture for stretchable electronics, which accommodates large deformations during stretching. Here, we show the effect of different geometrical morphologies on the deformation behavior of the spiral island network. We use numerical modeling to calculate the stresses and strains in the spiral interconnects under the prescribed displacement of 1000 μm. Our result shows that spiral arm elongation depends on the angular position of that particular spiral in the array. We also introduce the concept of a unit-cell, which fairly replicates the deformation mechanism for full complex hexagon, diamond, and square shaped arrays. The spiral interconnects which are axially connected between displaced and fixed islands attain higher stretchability and thus experience the maximum deformations. We perform tensile testing of 3D printed replica and find that experimental observations corroborate with theoretical study.

  2. Spiral: a new equipment for exotic nuclei; Spiral: un nouvel equipement pour les noyaux exotiques

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-02-01

    This document presents the GANIL activities and more specially the SPIRAL project. The missions of the GANIL are to allow scientists fundamental researches in Nuclear Physics and to develop applications for heavy ions in other domains. Spiral is an european project, decided by NuPECC (NUclear Physics European Collaboration Committee). It is a first generation equipment allowing the production and the acceleration of light and moderately heavy nuclei at energy range of 2 to 25 MeV/nucleus. (A.L.B.)

  3. VTVL concept optimisation of the landing gear

    Directory of Open Access Journals (Sweden)

    Camelia Elena MUNTEANU

    2017-03-01

    Full Text Available Vertical takeoff, vertical landing (VTVL is a subject of international interest at the moment thanks to the successful recovery of the Blue Origin vehicle. Aggressive weight targets with a short development time in the aerospace and space industry clearly need an integration of advanced computer aided structural optimization methods. Topological optimization is used from the concept phase of a design process development in order to obtain a fundamental design approach. The aim of the article is to determine the principal directions for distribution of the material for a VTVL landing gear within the specified volume in order to obtain the initial design approach. To achieve the maximum performance within the studied component, the result is then refined from a manufacturability point of view. The use of such methods notably reduces the development iterations between the design and stress departments. Thus, the overall time is reduced which translates into a lower overall cost and shorter time development from the concept to the final product.

  4. Continued Evaluation of Gear Condition Indicator Performance on Rotorcraft Fleet

    Science.gov (United States)

    Delgado, Irebert R.; Dempsey, Paula J.; Antolick, Lance J.; Wade, Daniel R.

    2013-01-01

    This paper details analyses of condition indicator performance for the helicopter nose gearbox within the U.S. Army's Condition-Based Maintenance Program. Ten nose gearbox data sets underwent two specific analyses. A mean condition indicator level analysis was performed where condition indicator performance was based on a 'batting average' measured before and after part replacement. Two specific condition indicators, Diagnostic Algorithm 1 and Sideband Index, were found to perform well for the data sets studied. A condition indicator versus gear wear analysis was also performed, where gear wear photographs and descriptions from Army tear-down analyses were categorized based on ANSI/AGMA 1010-E95 standards. Seven nose gearbox data sets were analyzed and correlated with condition indicators Diagnostic Algorithm 1 and Sideband Index. Both were found to be most responsive to gear wear cases of micropitting and spalling. Input pinion nose gear box condition indicators were found to be more responsive to part replacement during overhaul than their corresponding output gear nose gear box condition indicators.

  5. Nonlinear dynamics of breathers in the spiral structures of magnets

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, V. V., E-mail: kiselev@imp.uran.ru; Raskovalov, A. A. [Russian Academy of Sciences, Mikheev Institute of Metal Physics, Ural Branch (Russian Federation)

    2016-06-15

    The structure and properties of pulsating solitons (breathers) in the spiral structures of magnets are analyzed within the sine-Gordon model. The breather core pulsations are shown to be accompanied by local shifts and oscillations of the spiral structure with the formation of “precursors” and “tails” in the moving soliton. The possibilities for the observation and excitation of breathers in the spiral structures of magnets and multiferroics are discussed.

  6. Compression of interstellar clouds in spiral density-wave shocks

    International Nuclear Information System (INIS)

    Woodward, P.R.

    1979-01-01

    A mechanism of triggering star formation by galactic shocks is discussed. The possibilty that shocks may form along spiral arms in the gaseous component of a galactic disk is by now a familiar feature of spiral wave theory. It was suggested by Roberts (1969) that these shocks could trigger star formation in narrow bands forming a coherent spiral pattern over most of the disk of a galaxy. Some results of computer simulations of such a triggering process for star formation are reported. (Auth.)

  7. Cochlea and other spiral forms in nature and art.

    Science.gov (United States)

    Marinković, Slobodan; Stanković, Predrag; Štrbac, Mile; Tomić, Irina; Ćetković, Mila

    2012-01-01

    The original appearance of the cochlea and the specific shape of a spiral are interesting for both the scientists and artists. Yet, a correlation between the cochlea and the spiral forms in nature and art has been very rarely mentioned. The aim of this study was to investigate the possible correlation between the cochlea and the other spiral objects in nature, as well as the artistic presentation of the spiral forms. We explored data related to many natural objects and examined 13,625 artworks created by 2049 artists. We also dissected 2 human cochleas and prepared histologic slices of a rat cochlea. The cochlea is a spiral, cone-shaped osseous structure that resembles certain other spiral forms in nature. It was noticed that parts of some plants are arranged in a spiral manner, often according to Fibonacci numbers. Certain animals, their parts, or their products also represent various types of spirals. Many of them, including the cochlea, belong to the logarithmic type. Nature created spiral forms in the living world to pack a larger number of structures in a limited space and also to improve their function. Because the cochlea and other spiral forms have a certain aesthetic value, many artists presented them in their works of art. There is a mathematical and geometric correlation between the cochlea and natural spiral objects, and the same functional reason for their formation. The artists' imagery added a new aspect to those domains. Obviously, the creativity of nature and Homo sapiens has no limits--like the infinite distal part of the spiral. Copyright © 2012 Elsevier Inc. All rights reserved.

  8. Diagnosis of pancreatic tumors by spiral angio CT

    International Nuclear Information System (INIS)

    Miura, Kohi; Nakao, Norio; Takayasu, Yukio; Okawa, Tomohisa

    1995-01-01

    Spiral angio were performed with injection of 30 ml of contrast material at a rate of 1 ml/sec with a scan delay of 6 sec through catheter into the celiac artery while the blood flow of the superior mesenteric artery (SMA) was occluded by the inflated balloon catheter. Spiral CT scans were obtained using Somatom Plus (Siemens). Parameter for spiral CT were 24-sec acquisition time, 5 mm collimation, 5 mm/sec table incrementation. Reconstructions were performed every 5 mm. Pancreatic cancers were characteristically depicted with spiral angio CT as hypodensity relative to normal enhanced pancreatic parenchyma. On dynamic angio CT studies performed in pancreatic cancers, the area of cancer and normal parenchyma had maximum level of enhancement at 10-15 sec after injection of contrast material via catheter into the celiac, and there was no difference in enhancement between tumor and normal parenchyma. On the other hand, the lesions of cancer were revealed as hypodensity with spiral angio CT. In case of chronic pancreatitis, the enhancement of the entire pancreas obtained with spiral angio CT was homogeneous. Insulinoma in the tail of pancreas was detected by spiral angio CT but was not detected by both selective angiography and conventional CT. Three-dimensional (3-D) rendering spiral angio CT data shows the extent of vascular involvement by pancreatic cancer and provides useful information for surgical planning. Spiral angio CT is the most useful procedure for diagnosis of pancreatic tumor. (author)

  9. SPIRAL2 Week 2012 - Slides of the presentations

    International Nuclear Information System (INIS)

    Staley, F.; Jacquemet, M.; Lewitowicz, M.; Bertrand, P.; Tuske, O.; Caruso, A.; Leyge, J.F.; Perrot, L.; Di Giacomo, M.; Ausset, P.; Moscatello, M.H.; Savalle, A.; Rannou, B.; Lambert, M.; Petit, E.; Hulin, X.; Barre-Boscher, N.; Tusseau-Nenez, S.; Tecchio, L.B.

    2013-01-01

    The main goal of the 5. edition of the SPIRAL2 Week is to present and discuss the current status of the SPIRAL2 project in front of a large community of scientists and engineers. The program of the meeting will include presentations on scientific and technical developments related to the baseline project, experiments and theory. The main topics to be discussed at the conference are: -) physics and detectors at SPIRAL2, -) driver accelerators, -) production of radioactive ion beams (RIB), -) safety, -) buildings and infrastructure, -) RIB facilities worldwide, and -) SPIRAL2 preparatory phase. This document is made up of the slides of the presentations

  10. Algorithms for computing efficient, electric-propulsion, spiralling trajectories

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop techniques for rapidly designing many-revolution, electric-propulsion, spiralling trajectories, including the effects of shadowing, gravity harmonics, and...

  11. On the nature of the ramified spiral structure of galaxies

    International Nuclear Information System (INIS)

    Mishurov, Yu.N.; Suchkov, A.A.

    1976-01-01

    The nature of large-scale branching of spiral arms observed in a number of galaxies has been explained in the framework of the density wave theory. The solutions of the dispersion equation of spiral waves of density relative to the wave number k(r) in the models of galaxies in the form of two discs rotating with different angular velocities have been shown to be branching functions of the parameter r (r is the galacto-centric distance) under definite conditions; it corresponds to the branching of spiral arms. Hydrodynamic and kinetic considerations are also presented. The last one makes possible the understanding several other structural properties of spiral galaxies

  12. Influence of excitability on unpinning and termination of spiral waves.

    Science.gov (United States)

    Luengviriya, Jiraporn; Sutthiopad, Malee; Phantu, Metinee; Porjai, Porramain; Kanchanawarin, Jarin; Müller, Stefan C; Luengviriya, Chaiya

    2014-11-01

    Application of electrical forcing to release pinned spiral waves from unexcitable obstacles and to terminate the rotation of free spiral waves at the boundary of excitable media has been investigated in thin layers of the Belousov-Zhabotinsky (BZ) reaction, prepared with different initial concentrations of H_{2}SO_{4}. Increasing [H_{2}SO_{4}] raises the excitability of the reaction and reduces the core diameter of free spiral waves as well as the wave period. An electric current with density stronger than a critical value Junpin causes a pinned spiral wave to drift away from the obstacle. For a given obstacle size, Junpin increases with [H_{2}SO_{4}]. Under an applied electrical current, the rotation center of a free spiral wave drifts along a straight path to the boundary. When the current density is stronger than a critical value Jterm, the spiral tip is forced to hit the boundary, where the spiral wave is terminated. Similar to Junpin for releasing a pinned spiral wave, Jterm also increases with [H_{2}SO_{4}]. These experimental findings were confirmed by numerical simulations using the Oregonator model, in which the excitability was adjusted via the ratio of the excitation rate to the recovery rate of the BZ reaction. Therefore, our investigation shows that decreasing the excitability can facilitate elimination of spiral waves by electrical forcing, either in the presence of obstacles or not.

  13. Epistaxis during nasotracheal intubation: a randomized trial of the Parker Flex-Tip™ nasal endotracheal tube with a posterior facing bevel versus a standard nasal RAE endotracheal tube.

    Science.gov (United States)

    Earle, Rosie; Shanahan, Enda; Vaghadia, Himat; Sawka, Andrew; Tang, Raymond

    2017-04-01

    Nasotracheal intubation is a widely performed technique to facilitate anesthesia induction during oral, dental, and maxillofacial surgeries. The technique poses several risks not encountered with oropharyngeal intubation, most commonly epistaxis due to nasal mucosal abrasion. The purpose of this study was to test whether the use of the Parker Flex-Tip™ (PFT) nasal endotracheal tube (ETT) with a posterior facing bevel reduces epistaxis when compared with the standard nasal RAE ETT with a leftward facing bevel. Sixty American Society of Anesthesiologists physical status I and II patients undergoing oral or maxillofacial surgery with nasotracheal intubation were recruited. Patients were randomized to either a standard nasal RAE ETT or a PFT nasal ETT. The ETT was thermosoftened and lubricated for both study groups prior to insertion, and the size of the tube was chosen at the discretion of the attending anesthesiologist. The primary outcome was the incidence of epistaxis, with a secondary outcome of epistaxis severity (scored as none, mild, moderate, or severe). An investigator measured both outcomes five minutes after intubation was completed. Mild or moderate epistaxis was experienced by 22 of 30 (73%) patients in the PFT group compared with 21 of 30 (70%) patients in the standard nasal RAE ETT group (absolute risk reduction, 3%; 95% confidence interval, -19 to 25; P = 0.78). There were no occurrences of severe epistaxis in either group. There was no difference in the incidence or severity of epistaxis following nasal intubation using the Parker Flex-Tip nasal ETT when compared with a standard nasal RAE ETT. This trial was registered at ClinicalTrials.gov, identifier: NCT02315677.

  14. Large rotorcraft transmission technology development program

    Science.gov (United States)

    Mack, J. C.

    1983-01-01

    Testing of a U.S. Army XCH-62 HLH aft rotor transmission under NASA Contract NAS 3-22143 was successfully completed. This test establishes the feasibility of large, high power rotorcraft transmissions as well as demonstrating the resolution of deficiencies identified during the HLH advanced technology programs and reported by USAAMRDLTR-77-38. Over 100 hours of testing was conducted. At the 100% design power rating of 10,620 horsepower, the power transferred through a single spiral bevel gear mesh is more than twice that of current helicopter bevel gearing. In the original design of these gears, industry-wide design methods were employed and failures were experienced which identified problem areas unique to gear size. To remedy this technology shortfall, a program was developed to predict gear stresses using finite element analysis for complete and accurate representation of the gear tooth and supporting structure. To validate the finite element methodology gear strain data from the existing U.S. Army HLH aft transmission was acquired, and existing data from smaller gears were made available.

  15. Gear Design Effects on the Performance of High Speed Helical Gear Trains as Used in Aerospace Drive Systems

    Science.gov (United States)

    Handschuh, R.; Kilmain, C.; Ehinger, R.; Sinusas, E.

    2013-01-01

    The performance of high-speed helical gear trains is of particular importance for tiltrotor aircraft drive systems. These drive systems are used to provide speed reduction / torque multiplication from the gas turbine output shaft and provide the necessary offset between these parallel shafts in the aircraft. Four different design configurations have been tested in the NASA Glenn Research Center, High Speed Helical Gear Train Test Facility. The design configurations included the current aircraft design, current design with isotropic superfinished gear surfaces, double helical design (inward and outward pumping), increased pitch (finer teeth), and an increased helix angle. All designs were tested at multiple input shaft speeds (up to 15,000 rpm) and applied power (up to 5,000 hp). Also two lubrication, system-related, variables were tested: oil inlet temperature (160 to 250 degF) and lubricating jet pressure (60 to 80 psig). Experimental data recorded from these tests included power loss of the helical system under study, the temperature increase of the lubricant from inlet to outlet of the drive system and fling off temperatures (radially and axially). Also, all gear systems were tested with and without shrouds around the gears. The empirical data resulting from this study will be useful to the design of future helical gear train systems anticipated for next generation rotorcraft drive systems.

  16. A Unified Scaling Law in Spiral Galaxies.

    Science.gov (United States)

    Koda; Sofue; Wada

    2000-03-01

    We investigate the origin of a unified scaling relation in spiral galaxies. Observed spiral galaxies are spread on a plane in the three-dimensional logarithmic space of luminosity L, radius R, and rotation velocity V. The plane is expressed as L~&parl0;VR&parr0;alpha in the I passband, where alpha is a constant. On the plane, observed galaxies are distributed in an elongated region which looks like the shape of a surfboard. The well-known scaling relations L-V (Tully-Fisher [TF] relation), V-R (also the TF relation), and R-L (Freeman's law) can be understood as oblique projections of the surfboard-like plane into two-dimensional spaces. This unified interpretation of the known scaling relations should be a clue to understand the physical origin of all the relations consistently. Furthermore, this interpretation can also explain why previous studies could not find any correlation between TF residuals and radius. In order to clarify the origin of this plane, we simulate formation and evolution of spiral galaxies with the N-body/smoothed particle hydrodynamics method, including cooling, star formation, and stellar feedback. Initial conditions are set to 14 isolated spheres with two free parameters, such as mass and angular momentum. The cold dark matter (h=0.5, Omega0=1) cosmology is considered as a test case. The simulations provide the following two conclusions: (1) The slope of the plane is well reproduced but the zero point is not. This zero-point discrepancy could be solved in a low-density (Omega00.5) cosmology. (2) The surfboard-shaped plane can be explained by the control of galactic mass and angular momentum.

  17. New compact cyclotron design for SPIRAL

    International Nuclear Information System (INIS)

    Duval, M.; Bourgarel, M.P.; Ripouteau, F.

    1995-01-01

    The SPIRAL project whose purpose is the production and the acceleration of radioactive nuclei is under realization at GANIL. The new facility uses a cyclotron as post accelerator taking place behind the present machine. The magnet structure is made of 4 independent return yokes and a common circular pole piece (3.5 m in diameter) with 4 sectors. The average induction needed is 1.56 Tesla with hill and valley gaps of respectively 0.12 and 0.3 m. The required field patterns are adjusted by means of circular trim coils located between the sectors and the pole piece. (author)

  18. Spiral Light Beams and Contour Image Processing

    Science.gov (United States)

    Kishkin, Sergey A.; Kotova, Svetlana P.; Volostnikov, Vladimir G.

    Spiral beams of light are characterized by their ability to remain structurally unchanged at propagation. They may have the shape of any closed curve. In the present paper a new approach is proposed within the framework of the contour analysis based on a close cooperation of modern coherent optics, theory of functions and numerical methods. An algorithm for comparing contours is presented and theoretically justified, which allows convincing of whether two contours are similar or not to within the scale factor and/or rotation. The advantages and disadvantages of the proposed approach are considered; the results of numerical modeling are presented.

  19. Controls and automation in the SPIRAL project

    International Nuclear Information System (INIS)

    Bothner, U.; Boulot, A.; Maherault, J.; Martial, L.

    1999-01-01

    The control and automation team of the R and D of Accelerator-Exotic Beam Department has had in the framework of SPIRAL collaboration the following tasks: 1. automation of the resonator high frequency equipment of the CIME cyclotron; 2. automation of the vacuum equipment, i.e. the low energy line (TBE), the CIME cyclotron, the low energy line (BE); 3. automation of load safety for power supply; 4. for each of these tasks a circuitry file based on the SCHEMA software has been worked out. The programs required in the automation of load safety for power supply (STEP5, PROTOOL, DESIGNER 4.1) were developed and implemented for PC

  20. Production and post acceleration scheme for spiral

    International Nuclear Information System (INIS)

    Bibet, D.

    2001-01-01

    SPIRAL, the R.I.B. facility of GANIL uses heavy ion beams to produce radioactive atoms inside a thick target. Atoms are ionised in a compact permanent magnet ECR ion source. The compact cyclotron CIME accelerates the radioactive ions in an energy range from 1.7 to 25 MeV/u. The cyclotron acts as a mass separator with resolving power of 2500. Plastic scintillator and silicon detectors are used to tune the machine at a very low intensity. An overview of the facility, stable beam tests results and the R and D program will be presented. (authors)

  1. SPIRAL2/DESIR high resolution mass separator

    Energy Technology Data Exchange (ETDEWEB)

    Kurtukian-Nieto, T., E-mail: kurtukia@cenbg.in2p3.fr [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Baartman, R. [TRIUMF, 4004 Wesbrook Mall, Vancouver B.C., V6T 2A3 (Canada); Blank, B.; Chiron, T. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Davids, C. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Delalee, F. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Duval, M. [GANIL, CEA/DSM-CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France); El Abbeir, S.; Fournier, A. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Lunney, D. [CSNSM-IN2P3-CNRS, Université de Paris Sud, F-91405 Orsay (France); Méot, F. [BNL, Upton, Long Island, New York (United States); Serani, L. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Stodel, M.-H.; Varenne, F. [GANIL, CEA/DSM-CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France); and others

    2013-12-15

    DESIR is the low-energy part of the SPIRAL2 ISOL facility under construction at GANIL. DESIR includes a high-resolution mass separator (HRS) with a designed resolving power m/Δm of 31,000 for a 1 π-mm-mrad beam emittance, obtained using a high-intensity beam cooling device. The proposed design consists of two 90-degree magnetic dipoles, complemented by electrostatic quadrupoles, sextupoles, and a multipole, arranged in a symmetric configuration to minimize aberrations. A detailed description of the design and results of extensive simulations are given.

  2. Temperature simulations for the SPIRAL ISOL target

    International Nuclear Information System (INIS)

    Maunoury, L.; Bajeat, O.; Lichtenthaler, R.; Villari, A.C.C.

    2001-01-01

    Simulations of the power deposition and target temperature distributions in the SPIRAL ISOL target are presented. These simulations consider different heavy-ion beams with intensities corresponding to 2 and 6 kW on a carbon target. A new solutions, which corresponds to the splitting of the production target into two parts, where the first is cooled and the second is heated, allows keeping the overall size of the target ensemble relatively small. An extrapolation of the considered target geometry to primary beam intensities up to 1 MW is also presented. (authors)

  3. Galaxy Zoo: dust in spiral galaxies star

    OpenAIRE

    Masters, Karen L.; Nichol, Robert; Bamford, Steven; Mosleh, Moein; Lintott, Chris J.; Andreescu, Dan; Edmondson, Edward M.; Keel, William C.; Murray, Phil; Raddick, M. Jordan; Schawinski, Kevin; Slosar, Anze; Szalay, Alexander S.; Thomas, Daniel; Vandenberg, Jan

    2010-01-01

    We investigate the effect of dust on spiral galaxies by measuring the inclination dependence of optical colours for 24 276 well-resolved Sloan Digital Sky Survey (SDSS) galaxies visually classified via the Galaxy Zoo project. We find clear trends of reddening with inclination which imply a total extinction from face-on to edge-on of 0.7, 0.6, 0.5 and 0.4 mag for the ugri passbands (estimating 0.3 mag of extinction in z band). We split the sample into ‘bulgy’ (early-type) and ‘discy’ (late-typ...

  4. Planet-driven Spiral Arms in Protoplanetary Disks. II. Implications

    Science.gov (United States)

    Bae, Jaehan; Zhu, Zhaohuan

    2018-06-01

    We examine whether various characteristics of planet-driven spiral arms can be used to constrain the masses of unseen planets and their positions within their disks. By carrying out two-dimensional hydrodynamic simulations varying planet mass and disk gas temperature, we find that a larger number of spiral arms form with a smaller planet mass and a lower disk temperature. A planet excites two or more spiral arms interior to its orbit for a range of disk temperatures characterized by the disk aspect ratio 0.04≤slant {(h/r)}p≤slant 0.15, whereas exterior to a planet’s orbit multiple spiral arms can form only in cold disks with {(h/r)}p≲ 0.06. Constraining the planet mass with the pitch angle of spiral arms requires accurate disk temperature measurements that might be challenging even with ALMA. However, the property that the pitch angle of planet-driven spiral arms decreases away from the planet can be a powerful diagnostic to determine whether the planet is located interior or exterior to the observed spirals. The arm-to-arm separations increase as a function of planet mass, consistent with previous studies; however, the exact slope depends on disk temperature as well as the radial location where the arm-to-arm separations are measured. We apply these diagnostics to the spiral arms seen in MWC 758 and Elias 2–27. As shown in Bae et al., planet-driven spiral arms can create concentric rings and gaps, which can produce a more dominant observable signature than spiral arms under certain circumstances. We discuss the observability of planet-driven spiral arms versus rings and gaps.

  5. SELF-DESTRUCTING SPIRAL WAVES: GLOBAL SIMULATIONS OF A SPIRAL-WAVE INSTABILITY IN ACCRETION DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Jaehan; Hartmann, Lee [Department of Astronomy, University of Michigan, 1085 S. University Ave., Ann Arbor, MI 48109 (United States); Nelson, Richard P.; Richard, Samuel, E-mail: jaehbae@umich.edu, E-mail: lhartm@umich.edu, E-mail: r.p.nelson@qmul.ac.uk, E-mail: samuel.richard@qmul.ac.uk [Astronomy Unit, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)

    2016-09-20

    We present results from a suite of three-dimensional global hydrodynamic simulations that shows that spiral density waves propagating in circumstellar disks are unstable to the growth of a parametric instability that leads to break down of the flow into turbulence. This spiral wave instability (SWI) arises from a resonant interaction between pairs of inertial waves, or inertial-gravity waves, and the background spiral wave. The development of the instability in the linear regime involves the growth of a broad spectrum of inertial modes, with growth rates on the order of the orbital time, and results in a nonlinear saturated state in which turbulent velocity perturbations are of a similar magnitude to those induced by the spiral wave. The turbulence induces angular momentum transport and vertical mixing at a rate that depends locally on the amplitude of the spiral wave (we obtain a stress parameter α ∼ 5 × 10{sup −4} in our reference model). The instability is found to operate in a wide range of disk models, including those with isothermal or adiabatic equations of state, and in viscous disks where the dimensionless kinematic viscosity ν ≤ 10{sup −5}. This robustness suggests that the instability will have applications to a broad range of astrophysical disk-related phenomena, including those in close binary systems, planets embedded in protoplanetary disks (including Jupiter in our own solar system) and FU Orionis outburst models. Further work is required to determine the nature of the instability and to evaluate its observational consequences in physically more complete disk models than we have considered in this paper.

  6. SELF-DESTRUCTING SPIRAL WAVES: GLOBAL SIMULATIONS OF A SPIRAL-WAVE INSTABILITY IN ACCRETION DISKS

    International Nuclear Information System (INIS)

    Bae, Jaehan; Hartmann, Lee; Nelson, Richard P.; Richard, Samuel

    2016-01-01

    We present results from a suite of three-dimensional global hydrodynamic simulations that shows that spiral density waves propagating in circumstellar disks are unstable to the growth of a parametric instability that leads to break down of the flow into turbulence. This spiral wave instability (SWI) arises from a resonant interaction between pairs of inertial waves, or inertial-gravity waves, and the background spiral wave. The development of the instability in the linear regime involves the growth of a broad spectrum of inertial modes, with growth rates on the order of the orbital time, and results in a nonlinear saturated state in which turbulent velocity perturbations are of a similar magnitude to those induced by the spiral wave. The turbulence induces angular momentum transport and vertical mixing at a rate that depends locally on the amplitude of the spiral wave (we obtain a stress parameter α ∼ 5 × 10 −4 in our reference model). The instability is found to operate in a wide range of disk models, including those with isothermal or adiabatic equations of state, and in viscous disks where the dimensionless kinematic viscosity ν ≤ 10 −5 . This robustness suggests that the instability will have applications to a broad range of astrophysical disk-related phenomena, including those in close binary systems, planets embedded in protoplanetary disks (including Jupiter in our own solar system) and FU Orionis outburst models. Further work is required to determine the nature of the instability and to evaluate its observational consequences in physically more complete disk models than we have considered in this paper.

  7. Estimation of seafloor impact from demersal trawls, seines and dredges based on gear design and dimensions

    DEFF Research Database (Denmark)

    Eigaard, Ole Ritzau; Bastardie, Francois; Breen, Michael

    a different approach using the gear itself (design and dimensions) for understanding and estimation of the physical interactions with the seafloor at the individual fishing operation level. With reference to the métier groupings of EU logbooks, we defined 17 distinct towed gear groups in European waters (11...... otter trawl groups, 3 beam trawl groups, 2 demersal seine groups, and 1 dredge group), for which we established seafloor “footprints”. The footprint of a gear was defined as the relative contribution from individual larger gear components, such as the trawl doors, sweeps and ground gear, to the total...... types based on a review of the scientific literature. For each defined gear group a vessel-size (kW or total length) – gear size (total gear width or circumference) relationship was estimated to enable the prediction of gear footprint area and sediment penetration from vessel size. The implications...

  8. Vibration and Operational Characteristics of a Composite-Steel (Hybrid) Gear

    Science.gov (United States)

    Handschuh, Robert F.; LaBerge, Kelsen E.; DeLuca, Samuel; Pelagalli, Ryan

    2014-01-01

    Hybrid gears have been tested consisting of metallic gear teeth and shafting connected by composite web. Both free vibration and dynamic operation tests were completed at the NASA Glenn Spur Gear Fatigue Test Facility, comparing these hybrid gears to their steel counterparts. The free vibration tests indicated that the natural frequency of the hybrid gear was approximately 800 Hz lower than the steel test gear. The dynamic vibration tests were conducted at five different rotational speeds and three levels of torque in a four square test configuration. The hybrid gears were tested both as fabricated (machined, composite layup, then composite cure) and after regrinding the gear teeth to the required aerospace tolerance. The dynamic vibration tests indicated that the level of vibration for either type of gearing was sensitive to the level of load and rotational speed.

  9. Propulsion using the electron spiral toroid

    International Nuclear Information System (INIS)

    Seward, Clint

    1998-01-01

    A new propulsion method is proposed which could potentially reduce propellant needed for space travel by three orders of magnitude. It uses the newly patented electron spiral toroid (EST), which stores energy as magnetic field energy. The EST is a hollow toroid of electrons, all spiraling in parallel paths in a thin outer shell. The electrons satisfy the coupling condition, forming an electron matrix. Stability is assured as long as the coupling condition is satisfied. The EST is held in place with a small external electric field; without an external magnetic field. The EST system is contained in a vacuum chamber. The EST can be thought of as an energetic entity, with electrons at 10,000 electron volts. Propulsion would not use combustion, but would heat propellant through elastic collisions with the EST surface and eject them for thrust. Chemical rocket combustion heats propellant to 4000 deg. C; an EST will potentially heat the propellant 29,000 times as much, reducing propellant needs accordingly. The thrust can be turned ON and OFF. The EST can be recharged as needed

  10. Optimising imaging parameters in experimental spiral CT

    International Nuclear Information System (INIS)

    Tiitola, M.; Vehmas, T.; Kivisaari, R.P.; Kivisaari, L.

    1997-01-01

    Purpose: This in vitro study was conducted to analyse lesion detection and relative radiation exposure in different CT techniques. Material and Methods: We used a plastic phantom (12 x 8 x 2 cm) containing holes filled with air or fluid of varying densities to simulate lesions. This was imaged with Siemens Somatom Plus S and GE High Speed Advantage units. We varied table feeds (3 and 6 mm/s in Siemens and 3 and 4.5 mm/s in GE) and increments (2 mm and 4 mm) while keeping collimation at 3 mm. The SmartScan program of GE and the reformating algorithm of Siemens were also analysed. To evaluate the different methods, the phatnom lesions were counted by 3 observers. Radiation exposures associated with each technique were also measured. Results: The images reformatted to a coronal direction were significantly inferior (p<0.01) to those in other techniques. The use of SmartScan did not influence lesion detection, nor did changes in pitch or increment. Spiral and non-spiral techniques proved to be equal. Radiation exposure was lowest when a greater pitch or the SmartScan program was used. Conclusion: Radiation exposure in CT can be limited without significantly impairing the image quality by using low-dose techniques. Reformatting to a coronal direction should be used with care as it debases the image quality. (orig.)

  11. Spiral-shaped reactor for water disinfection

    KAUST Repository

    Soukane, Sofiane

    2016-04-20

    Chlorine-based processes are still widely used for water disinfection. The disinfection process for municipal water consumption is usually carried out in large tanks, specifically designed to verify several hydraulic and disinfection criteria. The hydrodynamic behavior of contact tanks of different shapes, each with an approximate total volume of 50,000 m3, was analyzed by solving turbulent momentum transport equations with a computational fluid dynamics code, namely ANSYS fluent. Numerical experiments of a tracer pulse were performed for each design to generate flow through curves and investigate species residence time distribution for different inlet flow rates, ranging from 3 to 12 m3 s−1. A new nature-inspired Conch tank design whose shape follows an Archimedean spiral was then developed. The spiral design is shown to strongly outperform the other tanks’ designs for all the selected plug flow criteria with an enhancement in efficiency, less short circuiting, and an order of magnitude improvement in mixing and dispersion. Moreover, following the intensification philosophy, after 50% reduction in its size, the new design retains its properties and still gives far better results than the classical shapes.

  12. Model for Spiral Galaxys Rotation Curves

    Science.gov (United States)

    Hodge, John

    2003-11-01

    A model of spiral galaxy dynamics is proposed. An expression describing the rotation velocity of particles v in a galaxy as a function of the distance from the center r (RC) is developed. The resulting, intrinsic RC of a galaxy is Keplerian in the inner bulge and rising in the disk region without modifying the Newtonian gravitational potential (MOND) and without unknown dark matter. The v^2 is linearly related to r of the galaxy in part of the rapidly rising region of the HI RC (RRRC) and to r^2 in another part of the RRRC. The r to discontinuities in the surface brightness versus r curve is related to the 21 cm line width, the measured mass of the central supermassive black hole (SBH), and the maximum v^2 in the RRRC. The distance to spiral galaxies can be calculated from these relationships that tightly correlates with the distance calculated using Cepheid variables. Differing results in measuring the mass of the SBH from differing measurement procedures are explained. This model is consistent with previously unexplained data, has predicted new relationships, and suggests a new model of the universe. Full text: http://web.infoave.net/ ˜scjh.

  13. Stellar complexes in spiral arms of galaxies

    Science.gov (United States)

    Efremov, Yu. N.

    The history of the introduction and development of the star complexes conception is briefly described. These large groups of stars were picked out and named as such ones in our Galaxy with argumentation and evidence for their physical unity (using the Cepheid variables the distances and ages of which are easy determined from their periods); anyway earlier the complexes were noted along the spiral arms of the Andromeda galaxy, but were not recognized as a new kind of star group. The chains of complexes along the spiral arms are observed quite rarely; their origin is explained by magneto- gravitational or purely gravitational instability developing along the arm. It is not clear why these chains are quite a rare phenomenon - and more so why sometimes the regular chain of complexes are observed in one arm only. Probably intergalactic magnetic field participated in formation of such chains. Apart from the complexes located along the arms, there are isolated giant complexes known (up to 700 pc in diameter) which look like super-gigantic but rather rarefied globular clusters. Until now only two of these formations are studied, in NGC 6946 and M51.

  14. Spiral blood flow in aorta-renal bifurcation models.

    Science.gov (United States)

    Javadzadegan, Ashkan; Simmons, Anne; Barber, Tracie

    2016-01-01

    The presence of a spiral arterial blood flow pattern in humans has been widely accepted. It is believed that this spiral component of the blood flow alters arterial haemodynamics in both positive and negative ways. The purpose of this study was to determine the effect of spiral flow on haemodynamic changes in aorta-renal bifurcations. In this regard, a computational fluid dynamics analysis of pulsatile blood flow was performed in two idealised models of aorta-renal bifurcations with and without flow diverter. The results show that the spirality effect causes a substantial variation in blood velocity distribution, while causing only slight changes in fluid shear stress patterns. The dominant observed effect of spiral flow is on turbulent kinetic energy and flow recirculation zones. As spiral flow intensity increases, the rate of turbulent kinetic energy production decreases, reducing the region of potential damage to red blood cells and endothelial cells. Furthermore, the recirculation zones which form on the cranial sides of the aorta and renal artery shrink in size in the presence of spirality effect; this may lower the rate of atherosclerosis development and progression in the aorta-renal bifurcation. These results indicate that the spiral nature of blood flow has atheroprotective effects in renal arteries and should be taken into consideration in analyses of the aorta and renal arteries.

  15. A comment on spiral motions in projective relativity

    International Nuclear Information System (INIS)

    Muzzio, J.C.; Lousto, C.O.; Instituto de Astronomia y Fisica del Espacio de la Republica Argentina)

    1985-01-01

    Astronomical evidence has been inadequately invoked to support projective relativity. The spiral structure cannot be explained just by the existence of spiral orbits, and the use of Oort's constant to support the theory is also a misunderstanding. Besides, some mathematical inaccuracies make the application invalid. (author)

  16. Drift of Spiral Waves in Complex Ginzburg-Landau Equation

    International Nuclear Information System (INIS)

    Yang Junzhong; Zhang Mei

    2006-01-01

    The spontaneous drift of the spiral wave in a finite domain in the complex Ginzburg-Landau equation is investigated numerically. By using the interactions between the spiral wave and its images, we propose a phenomenological theory to explain the observations.

  17. Strained spiral vortex model for turbulent fine structure

    Science.gov (United States)

    Lundgren, T. S.

    1982-01-01

    A model for the intermittent fine structure of high Reynolds number turbulence is proposed. The model consists of slender axially strained spiral vortex solutions of the Navier-Stokes equation. The tightening of the spiral turns by the differential rotation of the induced swirling velocity produces a cascade of velocity fluctuations to smaller scale. The Kolmogorov energy spectrum is a result of this model.

  18. Nonuniqueness of self-propagating spiral galaxy models

    International Nuclear Information System (INIS)

    Freedman, W.L.; Madore, B.F.

    1984-01-01

    We demonstrate the nonuniqueness of the basic assumptions leading to spiral structure in self-propagating star formation models. Even in the case where star formation occurs purely spontaneously and does not propagate, we have generated spiral structure by adopting the radically different assumption where star formation is systematically inhibited

  19. A Fundamental Plane of Spiral Structure in Disk Galaxies

    NARCIS (Netherlands)

    Davis, Benjamin L.; Kennefick, Daniel; Kennefick, Julia; Westfall, Kyle B.; Shields, Douglas W.; Flatman, Russell; Hartley, Matthew T.; Berrier, Joel C.; Martinsson, Thomas P. K.; Swaters, Rob A.

    Spiral structure is the most distinctive feature of disk galaxies and yet debate persists about which theory of spiral structure is correct. Many versions of the density wave theory demand that the pitch angle be uniquely determined by the distribution of mass in the bulge and disk of the galaxy. We

  20. Profiles of the stochastic star formation process in spiral galaxies

    International Nuclear Information System (INIS)

    Comins, N.

    1981-01-01

    The formation of spiral arms in disc galaxies is generally attributed to the effects of spiral density waves. These relatively small (i.e. 5 per cent) non-axisymmetric perturbations of the interstellar medium cause spiral arms highlighted by O and B type stars to be created. In this paper another mechanism for spiral arm formation, the stochastic self-propagating star formation (SSPSF) process is examined. The SSPSF process combines the theory that shock waves from supernovae will compress the interstellar medium to create new stars, some of which will be massive enough to also supernova, with a disc galaxy's differential rotation to create spiral arms. The present work extends this process to the case where the probability of star formation from supernova shocks decreases with galactic radius. Where this work and previous investigations overlap (namely the uniform probability case), the agreement is very good, pretty spirals with various numbers of arms are generated. The decreasing probability cases, taken to vary as rsup(-j), still form spiral arms for 0 1.5 the spiral structure is essentially non-existent. (author)

  1. The cold interstellar medium - An HI view of spiral galaxies

    NARCIS (Netherlands)

    Sancisi, R; Bender, R; Davies, RL

    1996-01-01

    An HI view of spiral galaxies is presented. In the first part the standard picture of isolated, normal spiral galaxies is briefly reviewed. In the second part attention is drawn to all those phenomena, such as tidal interactions, accretion and mergers, that depend on the galaxy environment and seem

  2. Star formation and the surface brightness of spiral galaxies

    International Nuclear Information System (INIS)

    Phillipps, S.; Disney, M.

    1985-01-01

    The (blue) surface brightness of spiral galaxies is significantly correlated with their Hα linewidth. This can be most plausibly interpreted as a correlation of surface brightness with star formation rate. There is also a significant difference in surface brightness between galaxies forming stars in a grand design spiral pattern and those with floc star formation regions. (author)

  3. Up the Down Spiral with English: Guidelines, Project Insight.

    Science.gov (United States)

    Catholic Board of Education, Diocese of Cleveland, OH.

    This curriculum guide presents the philosophy, objectives, and processes which unify a student-centered English program based on Jerome Bruner's concept of the spiral curriculum. To illustrate the spiraling of the learning process (i.e., engagement, perception, interpretation, evaluation, and personal integration), the theme of "hero" is traced…

  4. Vibration Propagation of Gear Dynamics in a Gear-Bearing-Housing System Using Mathematical Modeling and Finite Element Analysis

    Science.gov (United States)

    Parker, Robert G.; Guo, Yi; Eritenel, Tugan; Ericson, Tristan M.

    2012-01-01

    Vibration and noise caused by gear dynamics at the meshing teeth propagate through power transmission components to the surrounding environment. This study is devoted to developing computational tools to investigate the vibro-acoustic propagation of gear dynamics through a gearbox using different bearings. Detailed finite element/contact mechanics and boundary element models of the gear/bearing/housing system are established to compute the system vibration and noise propagation. Both vibration and acoustic models are validated by experiments including the vibration modal testing and sound field measurements. The effectiveness of each bearing type to disrupt vibration propagation is speed-dependent. Housing plays an important role in noise radiation .It, however, has limited effects on gear dynamics. Bearings are critical components in drivetrains. Accurate modeling of rolling element bearings is essential to assess vibration and noise of drivetrain systems. This study also seeks to fully describe the vibro-acoustic propagation of gear dynamics through a power-transmission system using rolling element and fluid film wave bearings. Fluid film wave bearings, which have higher damping than rolling element bearings, could offer an energy dissipation mechanism that reduces the gearbox noise. The effectiveness of each bearing type to disrupt vibration propagation in explored using multi-body computational models. These models include gears, shafts, rolling element and fluid film wave bearings, and the housing. Radiated noise is mapped from the gearbox surface to surrounding environment. The effectiveness of rolling element and fluid film wave bearings in breaking the vibro-acoustic propagation path from the gear to the housing is investigated.

  5. The Selected Problems of Studies of Aircraft Landing Gear

    Directory of Open Access Journals (Sweden)

    Rośkowicz Marek

    2016-12-01

    Full Text Available The article portrays the results of experimental studies conducted in the field of static strength test of main landing gear of lightweight aircraft as well as in the area of establishing the pneumatic tyre characteristics of main landing gear. The studies were carried out in compliance with methodologies of performing studies for the purposes of solutions implemented in aviation structures. It was stated that static strength tests of landing gear should not be done with the use of shock absorbers, due to the fact that this element, distinguished by high viscoelastic properties, by being statically loaded, is subject to displacements that do not occur during normal operation of the aircraft. Excessive displacements of shock absorber result in the load distribution in other landing gear elements being incompatible with project assumptions, which in turn leads to this strength test being interrupted, bearing in mind significantly lower loads than anticipated. It was also concluded that in order to determine pneumatic tyre characteristics it is not necessary to carry out tests on the whole landing gear strut, because the results obtained in the compression test of the wheel itself with pneumatic tyre are identical as the results acquired during tests conducted in accordance with methodology. Test preparation process with the use of the wheel itself and its realization is less time-consuming, less expensive and does not entail the necessity to build complex test stands.

  6. Materials and lubrication for gear and bearing surfaces in uhv

    International Nuclear Information System (INIS)

    Kirby, R.E.; Collet, G.J.; Garwin, E.L.

    1980-06-01

    During design and construction of the SLAC polarized LEED (PLEED) system, a search was made for a dependable gear, bearing, and lubrication system for the computer-controlled Faraday cup used to measure diffracted beams. Components must be nonmagnetic, bakeable to 250 0 C, and at room temperature must operate at pressures in the 10 -9 to 10 -10 Pa range. A test system was constructed which incorporated a meshed pair of dissimilar pitch diameter spur gears, one of which was confined to (by bushings) and rotated on a fixed shaft, while the other gear was driven by a commercial rotary motion feedthrough which was rotated by a servo motor driven in sine fashion with a direction reversal every six turns and peak speeds of 50 rpm. The criterion for a successful pair was approx. 10 5 turns, the life rating for the feedthrough. Pairs had actual turn counts from less than 1 to 91,000. Materials for gears included stainless steel, beryllium copper, and aluminum alloys. Lubricants used singly and in concert were MoS 2 , WS 2 , Ag, hard chrome, and a MoS 2 -graphite-sodium silicate mixture. The successful gear pair was Ag-plated Al alloy and MoS 2 -graphite-sodium silicate-coated Be-Cu. Subsequent performance in the PLEED system after repeated bakeouts will also be discussed

  7. Gear Mesh Loss-of-Lubrication Experiments and Analytical Simulation

    Science.gov (United States)

    Handschuh, Robert F.; Polly, Joseph; Morales, Wilfredo

    2011-01-01

    An experimental program to determine the loss-of-lubrication (LOL) characteristics of spur gears in an aerospace simulation test facility has been completed. Tests were conducted using two different emergency lubricant types: (1) an oil mist system (two different misted lubricants) and (2) a grease injection system (two different grease types). Tests were conducted using a NASA Glenn test facility normally used for conducting contact fatigue. Tests were run at rotational speeds up to 10000 rpm using two different gear designs and two different gear materials. For the tests conducted using an air-oil misting system, a minimum lubricant injection rate was determined to permit the gear mesh to operate without failure for at least 1 hr. The tests allowed an elevated steady state temperature to be established. A basic 2-D heat transfer simulation has been developed to investigate temperatures of a simulated gear as a function of frictional behavior. The friction (heat generation source) between the meshing surfaces is related to the position in the meshing cycle, the load applied, and the amount of lubricant in the contact. Experimental conditions will be compared to those from the 2-D simulation.

  8. Effects on Diagnostic Parameters After Removing Additional Synchronous Gear Meshes

    Science.gov (United States)

    Decker, Harry J.

    2003-01-01

    Gear cracks are typically difficult to diagnose with sufficient time before catastrophic damage occurs. Significant damage must be present before algorithms appear to be able to detect the damage. Frequently there are multiple gear meshes on a single shaft. Since they are all synchronous with the shaft frequency, the commonly used synchronous averaging technique is ineffective in removing other gear mesh effects. Carefully applying a filter to these extraneous gear mesh frequencies can reduce the overall vibration signal and increase the accuracy of commonly used vibration metrics. The vibration signals from three seeded fault tests were analyzed using this filtering procedure. Both the filtered and unfiltered vibration signals were then analyzed using commonly used fault detection metrics and compared. The tests were conducted on aerospace quality spur gears in a test rig. The tests were conducted at speeds ranging from 2500 to 5000 revolutions per minute and torques from 184 to 228 percent of design load. The inability to detect these cracks with high confidence results from the high loading which is causing fast fracture as opposed to stable crack growth. The results indicate that these techniques do not currently produce an indication of damage that significantly exceeds experimental scatter.

  9. Unilateral maxillary molar distalization with zygoma-gear appliance.

    Science.gov (United States)

    Kilkis, Dogan; Bayram, Mehmet; Celikoglu, Mevlut; Nur, Metin

    2012-08-01

    The aim of this study was to present the orthodontic treatment of a 15-year-old boy with a unilateral maxillary molar distalization system, called the zygoma-gear appliance. It consisted of a zygomatic anchorage miniplate, an inner bow, and a Sentalloy closed coil spring (GAC International, Bohemia, NY). A distalizing force of 350 g was used during the distalization period. The unilateral Class II malocclusion was corrected in 5 months with the zygoma-gear appliance. The maxillary left first molar showed distalization of 4 mm with an inclination of 3°. The maxillary premolars moved distally with the help of the transseptal fibers. In addition, there were slight decreases in overjet (-0.5 mm) and maxillary incisor inclination (-1°), indicating no anchorage loss from the zygoma-gear appliance. Preadjusted fixed appliances (0.022 × 0.028-in, MBT system; 3M Unitek, Monrovia, Calif) were placed in both arches to achieve leveling and alignment. After 14 months of unilateral distalization with the zygoma-gear appliance and fixed appliances, Class I molar and canine relationships were established with satisfactory interdigitation of the posterior teeth. Acceptable overjet and overbite were also achieved. This article shows that this new system, the zygoma-gear appliance, can be used for unilateral maxillary molar distalization without anchorage loss. Copyright © 2012 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  10. Topographic Beta Spiral and Onshore Intrusion of the Kuroshio Current

    Science.gov (United States)

    Yang, De-Zhou; Huang, Rui Xin; Yin, Bao-shu; Feng, Xing-Ru; Chen, Hai-ying; Qi, Ji-Feng; Xu, Ling-jing; Shi, Yun-long; Cui, Xuan; Gao, Guan-Dong; Benthuysen, Jessica A.

    2018-01-01

    The Kuroshio intrusion plays a vitally important role in carrying nutrients to marginal seas. However, the key mechanism leading to the Kuroshio intrusion remains unclear. In this study we postulate a mechanism: when the Kuroshio runs onto steep topography northeast of Taiwan, the strong inertia gives rise to upwelling over topography, leading to a left-hand spiral in the stratified ocean. This is called the topographic beta spiral, which is a major player regulating the Kuroshio intrusion; this spiral can be inferred from hydrographic surveys. In the world oceans, the topographic beta spirals can be induced by upwelling generated by strong currents running onto steep topography. This is a vital mechanism regulating onshore intruding flow and the cross-shelf transport of energy and nutrients from the Kuroshio Current to the East China Sea. This topographic beta spiral reveals a long-term missing link between the oceanic general circulation theory and shelf dynamic theory.

  11. Spatial and mass distributions of molecular clouds and spiral structure

    International Nuclear Information System (INIS)

    Kwan, J.; Valdes, F.; National Optical Astronomy Observatories, Tucson, AZ)

    1987-01-01

    The growth of molecular clouds resulting from cloud-cloud collisions and coalescence in the Galactic ring between 4 and 8 kpc are modeled, taking into account the presence of a spiral potential and the mutual cloud-cloud gravitational attraction. The mean lifetime of molecular clouds is determined to be about 200 million years. The clouds are present in both spiral arm and interarm regions, but a spiral pattern in their spatial distribution is clearly discernible, with the more massive clouds showing a stronger correlation with the spiral arms. As viewed from within the Galactic disk, however, it is very difficult to ascertain that the molecular cloud distribution in longitude-velocity space has a spiral pattern. 19 references

  12. Suppression of Spiral Wave in Modified Orengonator Model

    International Nuclear Information System (INIS)

    Ma Jun; Wang Chunni; Jin Wuyin; Yi Ming

    2008-01-01

    In this paper, a spatial perturbation scheme is proposed to suppress the spiral wave in the modified Orengonator model, which is used to describe the chemical reaction in the light-sensitive media. The controllable external illumination Φ is perturbed with a spatial linear function. In our numerical simulation, the scheme is investigated by imposing the external controllable illumination on the space continuously and/or intermittently. The numerical simulation results confirm that the stable rotating spiral wave still can be removed with the scheme proposed in this paper even if the controllable Φ changed vs. time and space synchronously. Then the scheme is also used to control the spiral wave and turbulence in the modified Fitzhugh-Nagumo model. It is found that the scheme is effective to remove the sable rotating and meandering spiral wave but it costs long transient period and intensity of the gradient parameter to eliminate the spiral turbulence

  13. Neutral hydrogen and spiral structure in M33

    International Nuclear Information System (INIS)

    Newton, K.

    1980-01-01

    Observations of neutral hydrogen (H I) in the galaxy M33 are presented which have sufficient angular resolution (47 x 93 arcsec) to distinguish detailed H I spiral structure for the first time. H I spiral features extend over the entire disc; the pattern is broken and multi-armed with the best-defined arms lying at radii outside the brightest optical features. Several very narrow spiral 'filaments' are unresolved by the beam, implying true widths -1 , is perturbed near the inner spiral arms. These perturbations agree with the predictions of density-wave theory but may simply arise from the self-gravity of massive arms whether or not they are a quasi-stationary wave phenomenon. If the outer spiral features form a rigidly rotating density-wave pattern, the absence of large radial streaming motions along the features implies a small pattern speed ( -1 kpc -1 ), with corotation in the outer parts of the disc. (author)

  14. A FUNDAMENTAL PLANE OF SPIRAL STRUCTURE IN DISK GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Benjamin L.; Kennefick, Daniel; Kennefick, Julia; Shields, Douglas W. [Arkansas Center for Space and Planetary Sciences, University of Arkansas, 346 1/2 North Arkansas Avenue, Fayetteville, AR 72701 (United States); Westfall, Kyle B. [Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, NL-9700 AV Groningen (Netherlands); Flatman, Russell [School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332 (United States); Hartley, Matthew T. [Department of Physics, University of Arkansas, 226 Physics Building, 835 West Dickson Street, Fayetteville, AR 72701 (United States); Berrier, Joel C. [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854-8019 (United States); Martinsson, Thomas P. K. [Leiden Observatory, P.O. Box 9513, NL-2300 RA Leiden (Netherlands); Swaters, Rob A., E-mail: bld002@email.uark.edu [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)

    2015-03-20

    Spiral structure is the most distinctive feature of disk galaxies and yet debate persists about which theory of spiral structure is correct. Many versions of the density wave theory demand that the pitch angle be uniquely determined by the distribution of mass in the bulge and disk of the galaxy. We present evidence that the tangent of the pitch angle of logarithmic spiral arms in disk galaxies correlates strongly with the density of neutral atomic hydrogen in the disk and with the central stellar bulge mass of the galaxy. These three quantities, when plotted against each other, form a planar relationship that we argue should be fundamental to our understanding of spiral structure in disk galaxies. We further argue that any successful theory of spiral structure must be able to explain this relationship.

  15. The study about planetary gearbox virtual prototyping with nonlinear gear contact characteristics

    International Nuclear Information System (INIS)

    Yin Huabing; Zhou Guangming

    2010-01-01

    The virtual prototypes of gear transmission system built in most multi-body dynamic software have difficulties in describing the gear mesh characteristics. The gear mesh contact is modelled as rigid contact and this is not accurate for the gear mesh contact, which is elastic or flexible. The gear contact formula used in the multi-body dynamic software does not reveal the gear contact nonlinear stiffness characteristic. The model built with gear meshing contact is difficult to solve because of its time-consuming algorithm. In the paper a new method is put forward to build the virtual prototype of planetary gearbox system according to the nonlinear mesh stiffness and mesh phase obtained through FEM models. This new FEM method of gear mesh stiffness calculation is much more accurate than the common formulas. The gear mesh nonlinear stiffness of sun gear- pinion and pinion-ring gear of all the planetary gear sets in gearbox are obtained through MATALB code, which is used to read and plot the analyzing result data. The gear mesh phase differences between different pinions with suns or rings of different planetary gear set can be also obtained. With all these data modelled in simulink (or other software) and integrated with the multi-body dynamic planetary gearbox model and the gear meshing contact problem in multi-body gear models is solved easily and accurately. The interfaces for gear mesh stiffness and mesh phases are designed for multi-body dynamic model and simulink. The nonlinear planetary gear set prototyping models are integrated to become the whole planetary gear box model and the whole vehicle system model built in multi-body dynamic software can be integrated to simulate different duty conditions. At last high speed input is put into the nonlinear planetary transmission model and the different duty cases are simulated. The dynamic characteristics of different parts are obtained. The dynamic characteristic comparison between nonlinear and linear models is made

  16. Imaging of head and neck tumors -- methods: CT, spiral-CT, multislice-spiral-CT

    International Nuclear Information System (INIS)

    Baum, Ulrich; Greess, Holger; Lell, Michael; Noemayr, Anton; Lenz, Martin

    2000-01-01

    Spiral-CT is standard for imaging neck tumors. In correspondence with other groups we routinely use spiral-CT with thin slices (3 mm), a pitch of 1.3-1.5 and an overlapping reconstruction increment (2-3 mm). In patients with dental fillings a short additional spiral parallel to the corpus of the mandible reduces artifacts behind the dental arches and improves the diagnostic value of CT. For the assessment of the base of the skull, the orbital floor, the palate and paranasal sinuses an additional examination in the coronal plane is helpful. Secondary coronal reconstructions of axial scans are helpful in the evaluation of the crossing of the midline by small tumors of the tongue base or palate. For an optimal vascular or tissue contrast a sufficient volume of contrast medium and a start delay greater than 70-80 s are necessary. In our opinion the best results can be achieved with a volume of 150 ml, a flow of 2.5 ml/s and a start delay of 80 s. Dynamic enhanced CT is only necessary in some special cases. There is clear indication for dynamic enhanced CT where a glomus tumor is suspected. Additional functional CT imaging during i-phonation and/or Valsalva's maneuver are of great importance to prove vocal cords mobility. Therefore, imaging during i-phonation is an elemental part of every thorough examination of the hypopharynx and larynx region. Multislice-spiral-CT allows almost isotropic imaging of the head and neck region and improves the assessment of tumor spread and lymph node metastases in arbitrary oblique planes. Thin structures (the base of the skull, the orbital floor, the hard palate) as well as the floor of the mouth can be evaluated sufficiently with multiplanar reformations. Usually, additional coronal scanning is not necessary with multislice-spiral-CT. Multislice-spiral-CT is especially advantageous in defining the critical relationships of tumor and lymph node metastases and for functional imaging of the hypopharynx and larynx not only in the

  17. Pathomorphism of spiral tibial fractures in computed tomography imaging.

    Science.gov (United States)

    Guzik, Grzegorz

    2011-01-01

    Spiral fractures of the tibia are virtually homogeneous with regard to their pathomorphism. The differences that are seen concern the level of fracture of the fibula, and, to a lesser extent, the level of fracture of the tibia, the length of fracture cleft, and limb shortening following the trauma. While conventional radiographs provide sufficient information about the pathomorphism of fractures, computed tomography can be useful in demonstrating the spatial arrangement of bone fragments and topography of soft tissues surrounding the fracture site. Multiple cross-sectional computed tomography views of spiral fractures of the tibia show the details of the alignment of bone chips at the fracture site, axis of the tibial fracture cleft, and topography of soft tissues that are not visible on standard radiographs. A model of a spiral tibial fracture reveals periosteal stretching with increasing spiral and longitudinal displacement. The cleft in tibial fractures has a spiral shape and its line is invariable. Every spiral fracture of both crural bones results in extensive damage to the periosteum and may damage bellies of the long flexor muscle of toes, flexor hallucis longus as well as the posterior tibial muscle. Computed tomography images of spiral fractures of the tibia show details of damage that are otherwise invisible on standard radiographs. Moreover, CT images provide useful information about the spatial location of the bone chips as well as possible threats to soft tissues that surround the fracture site. Every spiral fracture of the tibia is associated with disruption of the periosteum. 1. Computed tomography images of spiral fractures of the tibia show details of damage otherwise invisible on standard radiographs, 2. The sharp end of the distal tibial chip can damage the tibialis posterior muscle, long flexor muscles of the toes and the flexor hallucis longus, 3. Every spiral fracture of the tibia is associated with disruption of the periosteum.

  18. Adaptive Landing Gear: Optimum Control Strategy and Potential for Improvement

    Directory of Open Access Journals (Sweden)

    Grzegorz Mikułowski

    2009-01-01

    Full Text Available An adaptive landing gear is a landing gear (LG capable of active adaptation to particular landing conditions by means of controlled hydraulic force. The objective of the adaptive control is to mitigate the peak force transferred to the aircraft structure during touch-down, and thus to limit the structural fatigue factor. This paper investigates the ultimate limits for improvement due to various strategies of active control. Five strategies are proposed and investigated numerically using a~validated model of a real, passive landing gear as a reference. Potential for improvement is estimated statistically in terms of the mean and median (significant peak strut forces as well as in terms of the extended safe sinking velocity range. Three control strategies are verified experimentally using a laboratory test stand.

  19. Worm gearing for valve automation; Schneckengetriebe fuer die Armaturenautomatisierung

    Energy Technology Data Exchange (ETDEWEB)

    Herbstritt, Michael [AUMA Riester GmbH und Co. KG, Muellheim (Germany)

    2010-11-15

    Part-turn gearboxes are indispensable for exertion of the torques necessary for large part-turn valves. Torque demand has increased in the past decade, as a result, for example, of the use of pipelines of ever greater diameters in large conurbations, and of the operation of such pipelines at ever higher pressures. The design principle of a worm gear is useful in this context. Worm gearing systems with initial torques of up to 675,000 Nm are now available. The design of gearing systems capable of handling forces of this magnitude necessitates great know-how and experience. The very maximum of reliability is a basic requirement for actuator systems for applications involving such dimensions, since a failure may have catastrophic consequences. (orig.)

  20. Geared-elevator flutter study. [transonic flutter characteristics of empennage

    Science.gov (United States)

    Ruhlin, C. L.; Doggett, R. V., Jr.; Gregory, R. A.

    1976-01-01

    The paper describes an experimental and analytical study of the transonic flutter characteristics of an empennage flutter model having an all-movable horizontal tail with a geared elevator. Two configurations were flutter tested: one with a geared elevator and one with a locked elevator with the model cantilever-mounted on a sting in the wind tunnel. The geared-elevator configuration fluttered experimentally at about 20% higher dynamic pressures than the locked-elevator configuration. The experimental flutter boundary was nearly flat at transonic speeds for both configurations. It was found that an analysis which treated the elevator as a discrete surface predicted flutter dynamic pressure levels better than analyses which treated the stabilizer and elevator as a warped surface. Warped-surface methods, however, predicted more closely the experimental flutter frequencies and Mach number trends.

  1. 3D MODELLING WITH THE SAMSUNG GEAR 360

    Directory of Open Access Journals (Sweden)

    L. Barazzetti

    2017-02-01

    Full Text Available The Samsung Gear 360 is a consumer grade spherical camera able to capture photos and videos. The aim of this work is to test the metric accuracy and the level of detail achievable with the Samsung Gear 360 coupled with digital modelling techniques based on photogrammetry/computer vision algorithms. Results demonstrate that the direct use of the projection generated inside the mobile phone or with Gear 360 Action Direction (the desktop software for post-processing have a relatively low metric accuracy. As results were in contrast with the accuracy achieved by using the original fisheye images (front and rear facing images in photogrammetric reconstructions, an alternative solution to generate the equirectangular projections was developed. A calibration aimed at understanding the intrinsic parameters of the two lenses camera, as well as their relative orientation, allowed one to generate new equirectangular projections from which a significant improvement of geometric accuracy has been achieved.

  2. Ideas for Testing of Planetary Gear Sets of Automotive Transmissions

    Directory of Open Access Journals (Sweden)

    Achtenová Gabriela

    2017-06-01

    Full Text Available The article describes the concept of modular stand, where is possible to provide tests of gear pairs with fixed axes from mechanical automotive gearboxes, as well as tests of separate planetary sets from automatic gearboxes. Special attention in the article will be paid to the variant dedicated for testing of planetary gear sets. This variant is particularly interesting because: 1 it is rarely described in the literature, and 2 this topology allows big simplification with respect to testing of standard gearwheels. In the planetary closed-loop stand it is possible to directly link two identical planetary sets. Without any bracing flange or other connecting clutches, shafts or gear sets, just two planetary sets face-to-face will be assembled and connected to the electric motor.

  3. An efficient finite element solution for gear dynamics

    International Nuclear Information System (INIS)

    Cooley, C G; Parker, R G; Vijayakar, S M

    2010-01-01

    A finite element formulation for the dynamic response of gear pairs is proposed. Following an established approach in lumped parameter gear dynamic models, the static solution is used as the excitation in a frequency domain solution of the finite element vibration model. The nonlinear finite element/contact mechanics formulation provides accurate calculation of the static solution and average mesh stiffness that are used in the dynamic simulation. The frequency domain finite element calculation of dynamic response compares well with numerically integrated (time domain) finite element dynamic results and previously published experimental results. Simulation time with the proposed formulation is two orders of magnitude lower than numerically integrated dynamic results. This formulation admits system level dynamic gearbox response, which may include multiple gear meshes, flexible shafts, rolling element bearings, housing structures, and other deformable components.

  4. Detection of Pitting in Gears Using a Deep Sparse Autoencoder

    Directory of Open Access Journals (Sweden)

    Yongzhi Qu

    2017-05-01

    Full Text Available In this paper; a new method for gear pitting fault detection is presented. The presented method is developed based on a deep sparse autoencoder. The method integrates dictionary learning in sparse coding into a stacked autoencoder network. Sparse coding with dictionary learning is viewed as an adaptive feature extraction method for machinery fault diagnosis. An autoencoder is an unsupervised machine learning technique. A stacked autoencoder network with multiple hidden layers is considered to be a deep learning network. The presented method uses a stacked autoencoder network to perform the dictionary learning in sparse coding and extract features from raw vibration data automatically. These features are then used to perform gear pitting fault detection. The presented method is validated with vibration data collected from gear tests with pitting faults in a gearbox test rig and compared with an existing deep learning-based approach.

  5. Torsional vibration signal analysis as a diagnostic tool for planetary gear fault detection

    Science.gov (United States)

    Xue, Song; Howard, Ian

    2018-02-01

    This paper aims to investigate the effectiveness of using the torsional vibration signal as a diagnostic tool for planetary gearbox faults detection. The traditional approach for condition monitoring of the planetary gear uses a stationary transducer mounted on the ring gear casing to measure all the vibration data when the planet gears pass by with the rotation of the carrier arm. However, the time variant vibration transfer paths between the stationary transducer and the rotating planet gear modulate the resultant vibration spectra and make it complex. Torsional vibration signals are theoretically free from this modulation effect and therefore, it is expected to be much easier and more effective to diagnose planetary gear faults using the fault diagnostic information extracted from the torsional vibration. In this paper, a 20 degree of freedom planetary gear lumped-parameter model was developed to obtain the gear dynamic response. In the model, the gear mesh stiffness variations are the main internal vibration generation mechanism and the finite element models were developed for calculation of the sun-planet and ring-planet gear mesh stiffnesses. Gear faults on different components were created in the finite element models to calculate the resultant gear mesh stiffnesses, which were incorporated into the planetary gear model later on to obtain the faulted vibration signal. Some advanced signal processing techniques were utilized to analyses the fault diagnostic results from the torsional vibration. It was found that the planetary gear torsional vibration not only successfully detected the gear fault, but also had the potential to indicate the location of the gear fault. As a result, the planetary gear torsional vibration can be considered an effective alternative approach for planetary gear condition monitoring.

  6. HOW TO STEER THE TRANSMISSION RATIO OF PLANETARY CONTINUOUSLY ADJUSTABLE GEAR TRAIN

    Directory of Open Access Journals (Sweden)

    A. M. Dankov

    2016-01-01

    Full Text Available The known attempts to create a continuously-adjustable gear train with solid gears have led to development of some so-called adaptive gears. The most structurally simple version of continuously- adjustable gear train is a two-wheel planetary gear. It is an obvious fact that an active regulation of gear ratio for the gear should be based on the presence of con- trolled elements (parameters and a mechanism for their control. In respect of the mentioned gear one of the controlled elements that is a compound central toothed gear has such controlled parameter as a nominal pitch diameter. In this case it can rotate or remain motionless. Other controlled element which is a planetary carrier has its own radius as a controlled parameter and makes a rotary motion with a great speed of a leading element. The purpose of the control mechanism is to ensure radial displacement of central toothed gear and planet gear sectors in the working gear. The paper describes the mechanism modifications and considers two variants for transfer of control action from its source to an object to be controlled. The transfer is ensured by mechanical gears (two variants and hydraulics.

  7. The Strength Analysis of Differential Planetary Gears of Gearbox for Concrete Mixer Truck

    Science.gov (United States)

    Bae, M. H.; Bae, T. Y.; Kim, D. J.

    2018-03-01

    The power train of mixer gearbox for concrete mixer truck includes differential planetary gears to get large reduction ratio for operating mixer a drum and simple structure. The planetary gears are very important part of a mixer gearbox where strength problems namely gear bending stress, gear compressive stress and scoring failure are the main concern. In the present study, calculating specifications of the differential planetary gears and analyzing the gear bending and compressive stresses as well as scoring factor of the differential planetary gears gearbox for an optimal design of the mixer gearbox in respect to cost and reliability are investigated. The analyses of actual gear bending and compressive stresses of the differential planetary gears using Lewes & Hertz equation and verifications of the calculated specifications of the differential planetary gears evaluate the results with the data of allowable bending and compressive stress from the Stress-No. of cycles curves of gears. In addition, we also analyze actual gear scoring factor as well as evaluate the possibility of scoring failure of the differential planetary gear.

  8. From design to manufacturing of asymmetric teeth gears using computer application

    Science.gov (United States)

    Suciu, F.; Dascalescu, A.; Ungureanu, M.

    2017-05-01

    The asymmetric cylindrical gears, with involutes teeth profiles having different base circle diameters, are nonstandard gears, used with the aim to obtain better function parameters for the active profile. We will expect that the manufacturing of these gears became possible only after the design and realization of some specific tools. The paper present how the computer aided design and applications developed in MATLAB, for obtain the geometrical parameters, in the same time for calculation some functional parameters like stress and displacements, transmission error, efficiency of the gears and the 2D models, generated with AUTOLISP applications, are used for computer aided manufacturing of asymmetric gears with standard tools. So the specific tools considered one of the disadvantages of these gears are not necessary and implicitly the expected supplementary costs are reduced. The calculus algorithm established for the asymmetric gear design application use the „direct design“ of the spur gears. This method offers the possibility of determining first the parameters of the gears, followed by the determination of the asymmetric gear rack’s parameters, based on those of the gears. Using original design method and computer applications have been determined the geometrical parameters, the 2D and 3D models of the asymmetric gears and on the base of these models have been manufacturing on CNC machine tool asymmetric gears.

  9. Hybrid Gear Preliminary Results-Application of Composites to Dynamic Mechanical Components

    Science.gov (United States)

    Handschuh, Robert F.; Roberts Gary D.; Sinnamon, R.; Stringer, David B.; Dykas, Brian D.; Kohlman, Lee W.

    2012-01-01

    Composite spur gears were fabricated and then tested at NASA Glenn Research Center. The composite material served as the web of the gear between the gear teeth and a metallic hub for mounting to the torque-applying shaft. The composite web was bonded only to the inner and outer hexagonal features that were machined from an initially all-metallic aerospace quality spur gear. The Hybrid Gear was tested against an all-steel gear and against a mating Hybrid Gear. As a result of the composite to metal fabrication process used, the concentricity of the gears were reduced from their initial high-precision value. Regardless of the concentricity error, the hybrid gears operated successfully for over 300 million cycles at 10000 rpm and 490 in.*lbs torque. Although the design was not optimized for weight, the composite gears were found to be 20% lighter than the all-steel gears. Free vibration modes and vibration/noise tests were also conduct to compare the vibration and damping characteristic of the Hybrid Gear to all-steel gears. The initial results indicate that this type of hybrid design may have a dramatic effect on drive system weight without sacrificing strength.

  10. Time domain series system definition and gear set reliability modeling

    International Nuclear Information System (INIS)

    Xie, Liyang; Wu, Ningxiang; Qian, Wenxue

    2016-01-01

    Time-dependent multi-configuration is a typical feature for mechanical systems such as gear trains and chain drives. As a series system, a gear train is distinct from a traditional series system, such as a chain, in load transmission path, system-component relationship, system functioning manner, as well as time-dependent system configuration. Firstly, the present paper defines time-domain series system to which the traditional series system reliability model is not adequate. Then, system specific reliability modeling technique is proposed for gear sets, including component (tooth) and subsystem (tooth-pair) load history description, material priori/posterior strength expression, time-dependent and system specific load-strength interference analysis, as well as statistically dependent failure events treatment. Consequently, several system reliability models are developed for gear sets with different tooth numbers in the scenario of tooth root material ultimate tensile strength failure. The application of the models is discussed in the last part, and the differences between the system specific reliability model and the traditional series system reliability model are illustrated by virtue of several numerical examples. - Highlights: • A new type of series system, i.e. time-domain multi-configuration series system is defined, that is of great significance to reliability modeling. • Multi-level statistical analysis based reliability modeling method is presented for gear transmission system. • Several system specific reliability models are established for gear set reliability estimation. • The differences between the traditional series system reliability model and the new model are illustrated.

  11. Magnetic transmission gear finite element simulation with iron pole hysteresis

    Science.gov (United States)

    Filippini, Mattia; Alotto, Piergiorgio; Glehn, Gregor; Hameyer, Kay

    2018-04-01

    Ferromagnetic poles in a magnetic transmission gear require particular attention during their design process. Usually, during the numerical simulation of these devices the effects of hysteresis for loss estimation are neglected and considered only during post-processing calculations. Since the literature lacks hysteresis models, this paper adopts a homogenized hysteretic model able to include eddy current and hysteresis losses in 2D laminated materials for iron poles. In this article the results related to the hysteresis in a magnetic gear are presented and compared to the non-hysteretic approach.

  12. Gear Fault Detection Based on Teager-Huang Transform

    Directory of Open Access Journals (Sweden)

    Hui Li

    2010-01-01

    Full Text Available Gear fault detection based on Empirical Mode Decomposition (EMD and Teager Kaiser Energy Operator (TKEO technique is presented. This novel method is named as Teager-Huang transform (THT. EMD can adaptively decompose the vibration signal into a series of zero mean Intrinsic Mode Functions (IMFs. TKEO can track the instantaneous amplitude and instantaneous frequency of the Intrinsic Mode Functions at any instant. The experimental results provide effective evidence that Teager-Huang transform has better resolution than that of Hilbert-Huang transform. The Teager-Huang transform can effectively diagnose the fault of the gear, thus providing a viable processing tool for gearbox defect detection and diagnosis.

  13. Procedure for the automatic mesh generation of innovative gear teeth

    Directory of Open Access Journals (Sweden)

    Radicella Andrea Chiaramonte

    2016-01-01

    Full Text Available After having described gear wheels with teeth having the two sides constituted by different involutes and their importance in engineering applications, we stress the need for an efficient procedure for the automatic mesh generation of innovative gear teeth. First, we describe the procedure for the subdivision of the tooth profile in the various possible cases, then we show the method for creating the subdivision mesh, defined by two series of curves called meridians and parallels. Finally, we describe how the above procedure for automatic mesh generation is able to solve specific cases that may arise when dealing with teeth having the two sides constituted by different involutes.

  14. Electron Beam Welding of Gear Wheels by Splitted Beam

    Directory of Open Access Journals (Sweden)

    Dřímal Daniel

    2014-06-01

    Full Text Available This contribution deals with the issue of electron beam welding of high-accurate gear wheels composed of a spur gearing and fluted shaft joined with a face weld for automotive industry. Both parts made of the high-strength low-alloy steel are welded in the condition after final machining and heat treatment, performed by case hardening, whereas it is required that the run-out in the critical point of weldment after welding, i. e. after the final operation, would be 0.04 mm max..

  15. Induction heating of gears - pulsing dual-frequency concept

    Directory of Open Access Journals (Sweden)

    R. Przyłucki

    2013-04-01

    Full Text Available The paper concerns analysis of gears hardening process. In order to obtain required temperature distribution several variations of single and combined frequencies for selected gear-wheel configurations were considered. The paper includes the calculation models and analysis of geometry and current intensity as well frequency influence on temperature distribution of the tooth surface. All calculations have been carried out by means of the use of Flux3D simulation program, which enables to provide, coupled electromagnetic and temperature fields analysis.

  16. Spiral model pilot project information model

    Science.gov (United States)

    1991-01-01

    The objective was an evaluation of the Spiral Model (SM) development approach to allow NASA Marshall to develop an experience base of that software management methodology. A discussion is presented of the Information Model (IM) that was used as part of the SM methodology. A key concept of the SM is the establishment of an IM to be used by management to track the progress of a project. The IM is the set of metrics that is to be measured and reported throughout the life of the project. These metrics measure both the product and the process to ensure the quality of the final delivery item and to ensure the project met programmatic guidelines. The beauty of the SM, along with the IM, is the ability to measure not only the correctness of the specification and implementation of the requirements but to also obtain a measure of customer satisfaction.

  17. SPIRAL 2 RFQ Prototype First Tests

    CERN Document Server

    Ferdinand, Robin; Congretel, G; Curtoni, Aline; Delferriere, Olivier; Di Giacomo, Marco; France, Alain; Leboeuf, Didier; Thinel, Jean; Toussaint, Jean-Christian

    2005-01-01

    The SPIRAL2 RFQ is designed to accelerate at 88MHz two kinds of charge-over-mass ratio, Q/A, particles. The proposed injector can accelerate a 5 mA deuteron beam (Q/A=1/2) or a 1 mA particles beam with q/A=1/3 up to 0.75 MeV/A. It is a CW machine which has to show stable operation, provide the request availability, have the minimum losses in order to minimize the activation constraints and show the best quality/cost ratio. The prototype of this 4-vane RFQ has been built and tested. It allowed to verify the mechanical assembly concept (RFQ without any brazing step). The full power was easily injected in the cavity, with no concerns for the RF joints. The paper describes the different achievements.

  18. Fluid flow in a spiral microfluidic duct

    Science.gov (United States)

    Harding, Brendan; Stokes, Yvonne

    2018-04-01

    We consider the steady, pressure driven flow of a viscous fluid through a microfluidic device having the geometry of a planar spiral duct with a slowly varying curvature and height smaller than width. For this problem, it is convenient to express the Navier-Stokes equations in terms of a non-orthogonal coordinate system. Then, after applying appropriate scalings, the leading order equations admit a relatively simple solution in the central region of the duct cross section. First-order corrections with respect to the duct curvature and aspect ratio parameters are also obtained for this region. Additional correction terms are needed to ensure that no slip and no penetration conditions are satisfied on the side walls. Our solutions allow for a top wall shape that varies with respect to the radial coordinate which allows us to study the flow in a variety of cross-sectional shapes, including trapezoidal-shaped ducts that have been studied experimentally. At leading order, the flow is found to depend on the local height and slope of the top wall within the central region. The solutions are compared with numerical approximations of a classical Dean flow and are found to be in good agreement for a small duct aspect ratio and a slowly varying and small curvature. We conclude that the slowly varying curvature typical of spiral microfluidic devices has a negligible impact on the flow in the sense that locally the flow does not differ significantly from the classical Dean flow through a duct having the same curvature.

  19. Research on vibration signal analysis and extraction method of gear local fault

    Science.gov (United States)

    Yang, X. F.; Wang, D.; Ma, J. F.; Shao, W.

    2018-02-01

    Gear is the main connection parts and power transmission parts in the mechanical equipment. If the fault occurs, it directly affects the running state of the whole machine and even endangers the personal safety. So it has important theoretical significance and practical value to study on the extraction of the gear fault signal and fault diagnosis of the gear. In this paper, the gear local fault as the research object, set up the vibration model of gear fault vibration mechanism, derive the vibration mechanism of the gear local fault and analyzes the similarities and differences of the vibration signal between the gear non fault and the gears local faults. In the MATLAB environment, the wavelet transform algorithm is used to denoise the fault signal. Hilbert transform is used to demodulate the fault vibration signal. The results show that the method can denoise the strong noise mechanical vibration signal and extract the local fault feature information from the fault vibration signal..

  20. Estimating seabed pressure from demersal trawls, seines, and dredges based on gear design and dimensions

    DEFF Research Database (Denmark)

    Eigaard, Ole Ritzau; Bastardie, Francois; Breen, Mike

    2016-01-01

    such as logbook data. Here, we take a different approach starting from the gear itself (design and dimensions) to estimate the physical interactions with the seabed at the level of the individual fishing operation. We defined 14 distinct towed gear groups in European waters (eight otter trawl groups, three beam...... trawl groups, two demersal seine groups, and one dredge group), for which we established gear “footprints”. The footprint of a gear is defined as the relative contribution from individual larger gear components, such as trawl doors, sweeps, and groundgear, to the total area and severity of the gear...... to enable the prediction of gear footprint area and sediment penetration from vessel size. Application of these relationships with average vessel sizes and towing speeds provided hourly swept-area estimates by métier. Scottish seining has the largest overall gear footprint of ∼1.6 km2 h−1 of which 0.08 km2...

  1. 14 CFR 23.729 - Landing gear extension and retraction system.

    Science.gov (United States)

    2010-01-01

    ... retracted) position. If switches are used, they must be located and coupled to the landing gear mechanical... burst, or rocks, water, and slush that may enter the landing gear bay. [Doc. No. 4080, 29 FR 17955, Dec...

  2. Magnetization reversal in ferromagnetic spirals via domain wall motion

    Science.gov (United States)

    Schumm, Ryan D.; Kunz, Andrew

    2016-11-01

    Domain wall dynamics have been investigated in a variety of ferromagnetic nanostructures for potential applications in logic, sensing, and recording. We present a combination of analytic and simulated results describing the reliable field driven motion of a domain wall through the arms of a ferromagnetic spiral nanowire. The spiral geometry is capable of taking advantage of the benefits of both straight and circular wires. Measurements of the in-plane components of the spirals' magnetization can be used to determine the angular location of the domain wall, impacting the magnetoresistive applications dependent on the domain wall location. The spirals' magnetization components are found to depend on the spiral parameters: the initial radius and spacing between spiral arms, along with the domain wall location. The magnetization is independent of the parameters of the rotating field used to move the domain wall, and therefore the model is valid for current induced domain wall motion as well. The speed of the domain wall is found to depend on the frequency of the rotating driving field, and the domain wall speeds can be reliably varied over several orders of magnitude. We further demonstrate a technique capable of injecting multiple domain walls and show the reliable and unidirectional motion of domain walls through the arms of the spiral.

  3. Galaxy Zoo: constraining the origin of spiral arms

    Science.gov (United States)

    Hart, Ross E.; Bamford, Steven P.; Keel, William C.; Kruk, Sandor J.; Masters, Karen L.; Simmons, Brooke D.; Smethurst, Rebecca J.

    2018-05-01

    Since the discovery that the majority of low-redshift galaxies exhibit some level of spiral structure, a number of theories have been proposed as to why these patterns exist. A popular explanation is a process known as swing amplification, yet there is no observational evidence to prove that such a mechanism is at play. By using a number of measured properties of galaxies, and scaling relations where there are no direct measurements, we model samples of SDSS and S4G spiral galaxies in terms of their relative halo, bulge and disc mass and size. Using these models, we test predictions of swing amplification theory with respect to directly measured spiral arm numbers from Galaxy Zoo 2. We find that neither a universal cored or cuspy inner dark matter profile can correctly predict observed numbers of arms in galaxies. However, by invoking a halo contraction/expansion model, a clear bimodality in the spiral galaxy population emerges. Approximately 40 per cent of unbarred spiral galaxies at z ≲ 0.1 and M* ≳ 1010M⊙ have spiral arms that can be modelled by swing amplification. This population display a significant correlation between predicted and observed spiral arm numbers, evidence that they are swing amplified modes. The remainder are dominated by two-arm systems for which the model predicts significantly higher arm numbers. These are likely driven by tidal interactions or other mechanisms.

  4. Propagation of spiral waves pinned to circular and rectangular obstacles.

    Science.gov (United States)

    Sutthiopad, Malee; Luengviriya, Jiraporn; Porjai, Porramain; Phantu, Metinee; Kanchanawarin, Jarin; Müller, Stefan C; Luengviriya, Chaiya

    2015-05-01

    We present an investigation of spiral waves pinned to circular and rectangular obstacles with different circumferences in both thin layers of the Belousov-Zhabotinsky reaction and numerical simulations with the Oregonator model. For circular objects, the area always increases with the circumference. In contrast, we varied the circumference of rectangles with equal areas by adjusting their width w and height h. For both obstacle forms, the propagating parameters (i.e., wavelength, wave period, and velocity of pinned spiral waves) increase with the circumference, regardless of the obstacle area. Despite these common features of the parameters, the forms of pinned spiral waves depend on the obstacle shapes. The structures of spiral waves pinned to circles as well as rectangles with the ratio w/h∼1 are similar to Archimedean spirals. When w/h increases, deformations of the spiral shapes are observed. For extremely thin rectangles with w/h≫1, these shapes can be constructed by employing semicircles with different radii which relate to the obstacle width and the core diameter of free spirals.

  5. Possiblity of substituting 12XH3A steel in the manufacture of gears for a Sova motorcycle gearing box

    Science.gov (United States)

    Abramov, L. M.; Karabanov, V. P.; Abramov, V. L.; Astakhin, A. S.

    1996-03-01

    The experimental work describes the possibility of substituting the expensive alloying steel 12XH3A for the low-cost material (steel 40X) in manufacturing gears of the motor cycle gearing box. It ban be achieved on the basis of the obtained results and with the help of laser melting treatment of small-alloying steel. We can speak about the dependence of laser melting radiation efficiency on the regimes and procedures. The breakage of the gearing box of the motor cycle 'Sova' may be explained by the low carry ability of its first gearing box gear. This investigation includes the determination of the cause of this problem. One of the most wide spread methods of such decisions is the substitution of the used materials by another. The most important criteria for the new materials are: (1) the increase of mechanical characteristics (solidity, plasticity); (2) the increase of such characteristics as hardness, specific percussive viscosity; (3) the improvement of the technological characteristics; (4) the condencention of the manufacturing expenditures (economical effect). In accordance with these creations some materials (35X, 40X, 20XH, 40XHM steels) were chosen. The best material is 40X steel, because it allows us to treat the gears by laser radiation with the surface melt. Surface melt allows us to produce: (1) martensite structure with high solidity and low percussive viscosity; (2) martensite structure with chrome carbides and high percussive viscosity, but low plasticity; (3) amorphous or monocrystallic structures with the best characteristics. The last structure has the best characteristics because dislocation defects in such material are practically absent. Also, the amorphous surface of the materials is the most interesting. The spirit of the investigation is to define the parameters of production such as radiation power, size of laser spot, and speed of spot.

  6. The effect of pitch in multislice spiral/helical CT

    International Nuclear Information System (INIS)

    Wang, G.; Vannier, M.W.

    2000-01-01

    The purpose of this study is to understand the effect of pitch on raw data interpolation in multislice spiral/helical computed tomography (CT) and provide guidelines for scanner design and protocol optimization. Multislice spiral CT is mainly characterized by the three parameters: the number of detector arrays, the detector collimation, and the table increment per x-ray source rotation. The pitch in multislice spiral CT is defined as the ratio of the table increment over the detector collimation in this study. In parallel to the current framework for studying longitudinal image resolution, the central fan-beam rays of direct and opposite directions are considered, assuming a narrow cone-beam angle. Generally speaking, sampling in the Radon domain by the direct and opposite central rays is nonuniform along the longitudinal axis. Using a recently developed methodology for quantifying the sensibility of signal reconstruction from non-uniformly sampled finite points, the effect of pitch on raw data interpolation is analyzed in multislice spiral CT. Unlike single-slice spiral CT, in which image quality decreases monotonically as the pitch increases, the sensibility of raw data interpolation in multislice spiral CT increases, suggesting that image quality does not decrease monotonically in this case. The most favorable pitch can be found from the sensitivity-slice spiral CT is provided. The study on the effect of pitch using the sensitivity analysis approach reveals the fundamental characteristics of raw data interpolation in multislice spiral CT, and gives insights into interaction between pitch and image quality. These results may be valuable for design of multislice spiral CT scanners and imaging protocol optimization in clinical applications. (authors)

  7. Dynamic load-sharing characteristic analysis of face gear power-split gear system based on tooth contact characteristics

    Science.gov (United States)

    Dong, Hao; Hu, Yahui

    2018-04-01

    The bend-torsion coupling dynamics load-sharing model of the helicopter face gear split torque transmission system is established by using concentrated quality standard, to analyzing the dynamic load-sharing characteristic. The mathematical models include nonlinear support stiffness, time-varying meshing stiffness, damping, gear backlash. The results showed that the errors collectively influenced the load sharing characteristics, only reduce a certain error, it is never fully reached the perfect loading sharing characteristics. The system load-sharing performance can be improved through floating shaft support. The above-method will provide a theoretical basis and data support for its dynamic performance optimization design.

  8. Fabrication techniques of X-ray spiral zone plates

    International Nuclear Information System (INIS)

    Gao Nan; Zhu Xiaoli; Li Hailiang; Xie Changqing

    2010-01-01

    The techniques to make X-ray spiral zone plates using electron beam and X-ray lithography were studied. A master mask was fabricated on polyimide membrane by E-beam lithography and micro-electroplating. Spiral zone plates were efficiently replicated by X-ray lithography and micro-electroplating. By combining the techniques, spiral zone plates at 1 keV were successfully fabricate. With an outermost zone width of the 200 nm, and the gold absorbers thickness of 700 nm, the high quality zone plates can be used for X-ray phase contrast microscopy.(authors)

  9. Comments on H. Arp 'The persistent problem of spiral galaxies'

    International Nuclear Information System (INIS)

    Alfven, H.

    1987-04-01

    In his paper 'The persistent problem of Spiral Galaxies' H. Arp criticises the standard theory of spiral galaxies and demonstrates that introduction of plasma theory is necessary in order to understand the structure of spiral galaxies. In the present paper arguments are given in support of Arp's theory and suggestions are made how Arp's ideas should be developed. An important result of Arp's new approach is that there is no convincing argument for the belief that there is a 'missing mass'. This is important from a cosmological point of view. (author)

  10. A Software Development Simulation Model of a Spiral Process

    Science.gov (United States)

    Mizell, Carolyn; Malone, Linda

    2007-01-01

    There is a need for simulation models of software development processes other than the waterfall because processes such as spiral development are becoming more and more popular. The use of a spiral process can make the inherently difficult job of cost and schedule estimation even more challenging due to its evolutionary nature, but this allows for a more flexible process that can better meet customers' needs. This paper will present a discrete event simulation model of spiral development that can be used to analyze cost and schedule effects of using such a process in comparison to a waterfall process.

  11. Investigation on filter method for smoothing spiral phase plate

    Science.gov (United States)

    Zhang, Yuanhang; Wen, Shenglin; Luo, Zijian; Tang, Caixue; Yan, Hao; Yang, Chunlin; Liu, Mincai; Zhang, Qinghua; Wang, Jian

    2018-03-01

    Spiral phase plate (SPP) for generating vortex hollow beams has high efficiency in various applications. However, it is difficult to obtain an ideal spiral phase plate because of its continuous-varying helical phase and discontinued phase step. This paper describes the demonstration of continuous spiral phase plate using filter methods. The numerical simulations indicate that different filter method including spatial domain filter, frequency domain filter has unique impact on surface topography of SPP and optical vortex characteristics. The experimental results reveal that the spatial Gaussian filter method for smoothing SPP is suitable for Computer Controlled Optical Surfacing (CCOS) technique and obtains good optical properties.

  12. Elimination of spiral chaos by periodic force for the Aliev-Panfilov model

    OpenAIRE

    Sakaguchi, Hidetsugu; Fujimoto, Takefumi

    2003-01-01

    Spiral chaos appears in the two dimensional Aliev-Panfilov model. The generation mechanism of the spiral chaos is related to the breathing instability of pulse trains. The spiral chaos can be eliminated by applying periodic force uniformly. The elimination of spiral chaos is most effective, when the frequency of the periodic force is close to that of the breathing motion.

  13. Research of Planetary Gear Fault Diagnosis Based on Permutation Entropy of CEEMDAN and ANFIS

    NARCIS (Netherlands)

    Kuai, Moshen; Cheng, Gang; Pang, Y.; Li, Yong

    2018-01-01

    For planetary gear has the characteristics of small volume, light weight and large transmission ratio, it is widely used in high speed and high power mechanical system. Poor working conditions result in frequent failures of planetary gear. A method is proposed for diagnosing faults in planetary gear

  14. Minimizing tooth bending stress in spur gears with simplified shapes of fillet and tool shape determination

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard

    2015-01-01

    by different standards, with the ISO standard probably being the most common one. Gears are manufactured using two principally different tools: rack tools and gear tools. In this work, the bending stress of involute teeth is minimized by shape optimization made directly on the final gear. This optimized shape...

  15. Light and Heavy Tactical Wheeled Vehicle Fuel Consumption Evaluations Using Fuel Efficient Gear Oils (FEGO)

    Science.gov (United States)

    2016-05-01

    UNCLASSIFIED LIGHT AND HEAVY TACTICAL WHEELED VEHICLE FUEL CONSUMPTION EVALUATIONS USING FUEL EFFICIENT GEAR OILS (FEGO) FINAL... HEAVY TACTICAL WHEELED VEHICLE FUEL CONSUMPTION EVALUATIONS USING FUEL EFFICIENT GEAR OILS (FEGO) FINAL REPORT TFLRF No. 477 by Adam C...August 2014 – March 2016 4. TITLE AND SUBTITLE LIGHT AND HEAVY TACTICAL WHEELED VEHICLE FUEL CONSUMPTION EVALUATIONS USING FEUL EFFICIENT GEAR OILS

  16. 77 FR 36998 - Proposed Information Collection; Comment Request; Mandatory Shrimp Vessel and Gear...

    Science.gov (United States)

    2012-06-20

    ... Collection; Comment Request; Mandatory Shrimp Vessel and Gear Characterization Survey AGENCY: National... under the Shrimp Fishery Management Plan (FMP). The regulations for the Gulf Shrimp Vessel and Gear... and Gear Characterization Form. The form will be provided by NMFS at the time of permit application...

  17. 78 FR 40436 - Proposed Information Collection; Comment Request; Mandatory Shrimp Vessel and Gear...

    Science.gov (United States)

    2013-07-05

    ... Collection; Comment Request; Mandatory Shrimp Vessel and Gear Characterization Survey AGENCY: National... under the Shrimp Fishery Management Plan (FMP). The regulations for the Gulf Shrimp Vessel and Gear... Gear Characterization Form. The form will be provided by NMFS at the time of permit application and...

  18. 46 CFR 78.47-55 - Instructions for changing steering gear.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 3 2010-10-01 2010-10-01 false Instructions for changing steering gear. 78.47-55... OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 78.47-55 Instructions for changing steering gear..., relating in order, the different steps to be taken in changing to the emergency steering gear. Each clutch...

  19. 76 FR 5402 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Gear...

    Science.gov (United States)

    2011-01-31

    ... for OMB Review; Comment Request; Gear Certification ACTION: Notice. SUMMARY: The Department of Labor...) sponsored information collection request (ICR) titled, ``Gear Certification,'' to the Office of Management... cranes, derricks, and accessory gear used in the longshoring, marine terminal, and shipyard industries...

  20. 46 CFR 196.37-33 - Instructions for changing steering gear.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Instructions for changing steering gear. 196.37-33... steering gear. (a) Instructions in at least 1/2 inch letters and figures shall be posted in the steering engineroom, relating in order, the different steps to be taken in changing to the emergency steering gear...