WorldWideScience

Sample records for bucket wheel excavators

  1. Method of Assessment of Hard Rock Workability using Bucket Wheel Excavators

    Science.gov (United States)

    Machniak, Łukasz; Kozioł, Wiesław

    2017-03-01

    A new hypothesis concerning a process of the mining solid rocks using bucket wheel excavators (BWE). Destroying of the rock mass structure is a result of breaking and not, as so far accepted, of cutting. This approach excludes, for the description of solid rock workability using bucket wheel excavators, used classifications based on individual linear or surface resistances of cutting. The possibility of a replacement mechanism for determining of the workability by bucket wheel excavators using rippers was assumed. On this basis, an innovative method for assessing the workability of solid rocks was developed, which is a combination of an derived empirical energy relationship LSE of breaking by tractor rippers from a compressive strength, a seismic wave velocity, a density of solid rock, and the modified classification of workability by bucket wheel excavators according to Bulukbasi (1991). The proposed method allows for multi-parameter assessment of the workability class based on the parameters that are independent variables in the specified dependencies.

  2. MPED: An ISRU Bucket Ladder Excavator Demonstrator System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Abstract: The Multi-Purpose Excavation Demonstrator (MPED) is a commercial effort and a third generation of technology, following Bucket Wheel Excavator and Bucket...

  3. Investigation of Bucket Wheel Excavator Lattice Structure Internal Stress in Harsh Environment through a Remote Measurement System

    Science.gov (United States)

    Risteiu, M.; Dobra, R.; Andras, I.; Roventa, M.; Lorincz, A.

    2017-06-01

    The paper shows the results of a lab model for strain gauges based measuring system for multiple measuring heads of the mechanical stress in lattice structures of the bucket wheel excavator for open pit mines-harsh environment. The system is designed around a microcontroller system. Because of specific working conditions, the measuring system sends data to a processing system (a PC with Matlab software), we have implemented a secure communication solution based on ISM standard, by using NRF24L01 module. The transceiver contains a fully integrated frequency synthesizer based on crystal oscillator, and a Enhanced ShockBurst™ protocol engine. The proposed solution has a current consumption around 9.0 mA at an output power of -6dBm and 12.3mA in RX mode. Built-in Power Down and Standby modes makes power saving easily realizable for our solution battery powered. The stress from structures is taken by specific strain gauges adapted to low frequency vibrations. We are using a precision 24-bit analog-to-digital converter (ADC) designed for weigh scales and industrial control applications to interface directly with a bridge sensor-instrumentation device, with low drift voltage, low noise, common mode rejection signal, frequency and temperature stability. As backup implementation for measurements a high speed storage implementation is used.

  4. Wear model of an excavator bucket

    Science.gov (United States)

    Sarychev, Vladimir D.; Granovskii, Alexey Yu.; Nevskii, Sergey A.; Konovalov, Sergey V.; Gromov, Victor E.

    2017-12-01

    A mathematical model describing wear of the interior faces of the excavator bucket during the long-termed operation is proposed. The model is based on the Navier-Stocks equation and boundary conditions. The bucket was modeled as a rectangular parallelepiped; one of its faces is permeable for a granular material, whereas the others meet the conditions of impermeability and adhesion. In the approximation of viscous fluid, motion equations of a granular material in the excavator bucket were solved by the finite elements method. The velocity distribution curves of material particles along the bucket surface are obtained. A vortex structure is revealed at the bottom-back wall edge of the bucket, and it is thought to be the reason for high wear in these zones. As shown by the granular material pressure distributed along the bucket walls, its maximum is at the bottom-back wall edge of the excavator bucket. It is considered to be the reason for high wear in the operation process. Therefore, the bottom and back walls of the excavator bucket should be coated with a composite armouring mesh via arc surfacing.

  5. Torsional Moment Measurement on Bucket Wheel Shaft of Giant Machine

    Directory of Open Access Journals (Sweden)

    Jiří FRIES

    2011-06-01

    Full Text Available Bucket wheel loading at the present time (torsional moment on wheel shaft, peripheral cutting force is determined from electromotor incoming power or reaction force measured on gearbox hinge. Both methods together are weighted by steel construction absorption of driving units and by inertial forces of motor rotating parts. In the article is described direct method of the torsional moment measurement, which eliminates mentioned unfavourable impacts except absorption of steel construction of bucket wheel itself.

  6. Method of defining rational parameters for excavator buckets vibrating devices in order to reduce soil adhesion

    Science.gov (United States)

    Zenkov, S. A.

    2017-10-01

    The article describes the method of defining rational parameters for excavator buckets vibrating devices in order to reduce soil adhesion under various operating conditions. The method includes limits formation, calculating geometric parameters of curved mold concentrator for excavator buckets with magnetostriction vibration exciters; calculating parameters of acoustic influence equipment; calculating power demand of equipment, defining adhesive forces of soil to buckets with given values of external factors; defining equipment operation mode (turn-on frequency, exposure time). Suggested method enables one to define required parameters of vibrating equipment to excavator buckets during the design phase.

  7. Comments on "Determination and Analysis of the Theoretical Production of a Bucket Wheel Excavator" / Uwagi I Komentarze Do Pracy: "Określanie I Analiza Teoretycznej Wydajności Pracy Koparki Wielonaczyniowej Kołowej"

    Science.gov (United States)

    Bošnjak, Srđan M.

    2015-03-01

    This paper comments on the recently published work dealing with the problem in the determination of the theoretical output of the bucket wheel excavator. It also includes remarks on the inadequacy in the problem approach and highlights the mistakes in the mathematical model. This work emphasizes the demand for a much wider and deeper approach to the problem of determining the output of the bucket wheel excavator. Opublikowany niedawno artykuł autorstwa Che i Chena (2014) poświecony jest ważnej kwestii jaką jest określenie teoretycznej wydajności koparki kołowej wielonaczyniowej. W załączonym przeglądzie literatury Che i Chen (2014) nie umieścili pozycji odnoszących się do metod urabiania, parametrów pracy koparki oraz teoretycznej wydajności wydobycia i być może to właśnie jest przyczyną pewnych niedokładności powstałych w trakcie rozwiązywania problemu. Intencją autora obecnej publikacji było: • Odniesienie się do krytycyzmu wyrażonego przez Che i Chena (2014) dotyczącego procedury obliczania prędkości w ruchu łukowym podanej w cytowanej literaturze przedmiotu (Pajer i in., 1971; Vetrov, 1971; Rasper, 1975; Durst i Vogt, 1988); • Zbadanie różnic pomiędzy procedurą określania teoretycznej wydajności zaproponowaną w pracy Che i Chena (2014) a odpowiednimi rozwiązaniami podanymi w literaturze; • Określenie prawidłowości i stosowalności teorii zaprezentowanej w pracy Che i Chena (2014) poprzez porównanie wyników uzyskanych z wykorzystaniem ich teorii oraz teorii podanych w wymienionych pozycjach literatury. W rozdziale 2 pracy (Che i Chen 2014) zatytułowanym " Uprzednio stosowane metody określania teoretycznej wydajności pracy koparki kołowej wielonaczyniowej" autorzy nie podali głównych odniesień literaturowych z których zaczerpnięte zostały równania (1)-(6)**. Ponadto, nie podali charakterystyki modelu działania koparki, na podstawie którego wyprowadzone zostały rzeczone równania, co stanowi powa

  8. Performance Evaluation of Bucket based Excavating, Loading and Transport (BELT) Equipment - An OEE Approach

    Science.gov (United States)

    Mohammadi, Mousa; Rai, Piyush; Gupta, Suprakash

    2017-03-01

    Overall Equipment Effectiveness (OEE) has been used since last over two decades as a measure of performance in manufacturing industries. Unfortunately, enough, application of OEE in mining and excavation industry has not been duly adopted. In this paper an effort has been made to identify the OEE for performance evaluation of Bucket based Excavating, Loading and Transport (BELT) equipment. The conceptual model of OEE, as used in the manufacturing industries, has been revised to adapt to the BELT equipment. The revised and adapted model considered the operational time, speed and bucket capacity utilization losses as the key OEE components for evaluating the performance of BELT equipment. To illustrate the efficacy of the devised model on real-time basis, a case study was undertaken on the biggest single bucket excavating equipment - the dragline, in a large surface coal mine. One-year data was collected in order to evaluate the proposed OEE model.

  9. MPED: An ISRU Bucket Ladder Excavator Demonstrator System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation is a planetary surface tool called the Multi Purpose Excavation Demonstrator (MPED), which is intended to both extract Lunar Soil to feed an...

  10. MATHEMATICAL MODEL OF ATTITUDE CONTROL BUCKET‐WHEEL EXCAVATOR

    Directory of Open Access Journals (Sweden)

    Ivana ONDERKOVÁ

    2013-07-01

    Full Text Available This lecture deals with the application problems of convertibility GPS system at paddle excavator K 800. The claims of the modern operating surface mining of the excavators requires a lot of information for monitoring of mining process, capacity mining, selective extraction etc. The utilization of monitoring the excavator setting by GPS system proved to be the only one proper because the receivers are resistant to the vibration, dust, temperature divergence and weather changeable. Only the direct contact with communications satellite is required. It means that they can´t be located in a metal construction space (shadow caused by construction elements, influence of electrical high voltage cables even they can´t be located close to the paddle wheel on the paddle boom (shadow possibility caused by cuttinng edge created during lower gangplanks mining. This is the reason that GPS receivers are set uppermost on the metal construction excavator and the mathematical formulation is required for determination of paddle wheel petting. The relations for calculation of the paddle wheel coordinate were defined mathematically and after that the mathematical model was composed.

  11. Designing Pattern Recognition-Based Method for Fast Visual Inspection of the Bucket Wheel Excavator Lattice Structure

    Science.gov (United States)

    Risteiu, M.; Lorincz, A.; Dobra, R.; Dasic, P.; Andras, I.; Roventa, M.

    2017-06-01

    The proposed paper shows some experimental results of a research in metallic structures inspection by using a high definition camera controller by high processing capabilities. The dedicated ARM Cortex-M4 initializes the ARM Cortex-M0 system for image acquiring. Then, by programming options, we are action for patterns (abnormal situations like metal cracks, or discontinuities) types and tuning, for enabling overexposure highlighting and adjusting camera brightness/exposure, to adjust minimum brightness, and to adjust the pattern’s teach threshold. The proposed system has been tested in normal lighting conditions from the typical site.

  12. Smart Calibration of Excavators

    DEFF Research Database (Denmark)

    Bro, Marie; Døring, Kasper; Ellekilde, Lars-Peter

    2005-01-01

    Excavators dig holes. But where is the bucket? The purpose of this report is to treat four different problems concerning calibrations of position indicators for excavators in operation at concrete construction sites. All four problems are related to the question of how to determine the precise...... geographic and/or site-relative position of a given excavator and its bucket. However, our presentations and solutions to the problems can, nevertheless, be read and studied in any order and independently of each other. This also implies and induces a gentle warning to the reader: The {\\em{notation}} need...

  13. Bucket foundations

    DEFF Research Database (Denmark)

    Foglia, Aligi; Ibsen, Lars Bo

    In this report, bearing behaviour and installation of bucket foundations are reviewed. Different methods and standards are compared with the experimental data presented in Foglia and Ibsen (2014a). The most important studies on these topics are suggested. The review is focused on the response...... of monopod bucket foundations supporting offshore wind turbines....

  14. Suction Buckets

    DEFF Research Database (Denmark)

    Feld, T.

    This Ph.D. thesis deals with bucket foundations and their applicability for offshore wind turbines. The main concern is the establishment of an analytical model for frictional materials, combined with simulations of buckets with varying geometry. An analytical model is proposed, consisting...... of different parts describing the penetration resistance during installation, the phenomenon critical suction and calculation methods for determination of the pullout force, respectively the response under combined loading, equivalent to ship impact, wave actions etc. A series of experimental tests conducted...... of simulating the change in size and shape of the failure locus in the H-M/D space, as revealed in the laboratory. An economic comparison between different foundation concepts is made. The advantages and disadvantages using bucket foundation are outlined. Concluding a design chart is proposed, based...

  15. Second-stage turbine bucket airfoil

    Science.gov (United States)

    Wang, John Zhiqiang; By, Robert Romany; Sims, Calvin L.; Hyde, Susan Marie

    2002-01-01

    The second-stage buckets have airfoil profiles substantially in accordance with Cartesian coordinate values of X, Y and Z set forth in inches in Table I wherein Z is a perpendicular distance from a plane normal to a radius of the turbine centerline and containing the X and Y values with the Z value commencing at zero in the X, Y plane at the radially innermost aerodynamic section of the airfoil and X and Y are coordinate values defining the airfoil profile at each distance Z. The X and Y values may be scaled as a function of the same constant or number to provide a scaled-up or scaled-down airfoil section for the bucket. The second-stage wheel has sixty buckets.

  16. The Monopod Bucket Foundation

    DEFF Research Database (Denmark)

    Bakmar, Christian LeBlanc; Ahle, Kim; Nielsen, Søren A.

    2009-01-01

    Following the successful installation of a prototype of a monopod bucket foundation, also called a “monopod suction caisson”, at Horns Rev 2 Offshore Wind Farm, Denmark, in 2009, DONG Energy is currently developing a commercialization strategy. The monopod bucket foundation is a promising...

  17. Percussive Excavation of Lunar Soil

    Science.gov (United States)

    Whittaker, Matthew P.

    2008-01-01

    It has been suggested using a percussive motion could improve the efficiency of excavation by up to 90%. If this is proven to be true it would be very beneficial to excavation projects on the Moon and Mars. The purpose of this study is to design, build and test a percussive tool which could dig a trench and then compare this data against that of a non-percussive tool of the same shape and size. The results of this test thus far have been inconclusive due to malfunctions in the testbed and percussive bucket; however, experimental results from small scale experiments confirm this higher efficiency and support further testing.

  18. Buckling of Bucket Foundations

    DEFF Research Database (Denmark)

    Madsen, Søren; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo

    2012-01-01

    In this paper, the risk of structural buckling during installation of large-diameter bucket foundations is addressed using numerical methods. Imperfect geometries are introduced based on the pre-buckling mode shapes from a linear Eigenvalue buckling analysis. Various imperfect geometries are intr......In this paper, the risk of structural buckling during installation of large-diameter bucket foundations is addressed using numerical methods. Imperfect geometries are introduced based on the pre-buckling mode shapes from a linear Eigenvalue buckling analysis. Various imperfect geometries...

  19. The Offshore Bucket Trail Installation

    DEFF Research Database (Denmark)

    Nielsen, Søren Andreas; Ibsen, Lars Bo

    The Bucket Trail Installation project has gathered a substantial amount of date in a unique soil database which enable update of the used standards for penetration prediction. This update will lead to less conservative design of bucket foundations and is vital for the aim of cost reduction...... in the offshore wind business. Furthermore is serial offshore operation with the bucket concept was demonstrated with achieving full installation depth and inclination within given tolerance....

  20. Recycler barrier RF buckets

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, C.M.; /Fermilab

    2011-03-01

    The Recycler Ring at Fermilab uses a barrier rf systems for all of its rf manipulations. In this paper, I will give an overview of historical perspective on barrier rf system, the longitudinal beam dynamics issues, aspects of rf linearization to produce long flat bunches and methods used for emittance measurements of the beam in the RR barrier rf buckets. Current rf manipulation schemes used for antiproton beam stacking and longitudinal momentum mining of the RR beam for the Tevatron collider operation are explained along with their importance in spectacular success of the Tevatron luminosity performance.

  1. Research on Trajectory Planning and Autodig of Hydraulic Excavator

    Directory of Open Access Journals (Sweden)

    Bin Zhang

    2017-01-01

    Full Text Available As the advances in computer control technology keep emerging, robotic hydraulic excavator becomes imperative. It can improve excavation accuracy and greatly reduce the operator’s labor intensity. The 12-ton backhoe bucket excavator has been utilized in this research work where this type of excavator is commonly used in engineering work. The kinematics model of operation device (boom, arm, bucket, and swing in excavator is established in both Denavit-Hartenberg coordinates for easy programming and geometric space for avoiding blind spot. The control approach is based on trajectory tracing method with displacements and velocities feedbacks. The trajectory planning and autodig program is written by Visual C++. By setting the bucket teeth’s trajectory, the program can automatically plan the velocity and acceleration of each hydraulic cylinder and motor. The results are displayed through a 3D entity simulation environment which can present real-time movements of excavator kinematics. Object-Oriented Graphics Rendering Engine and skeletal animation are used to give accurate parametric control and feedback. The simulation result shows that a stable linear autodig can be achieved. The errors between trajectory planning command and simulation model are analyzed.

  2. Setting up excavators with growing cracks in their metal structures for repairs

    Science.gov (United States)

    Nasonov, M. Y.; Lykov, Y. V.

    2017-10-01

    When determining the loads that arise on the working bodies of excavators, it is assumed that the developed soils and blown rock are homogeneous and are cut by a bucket in the form of shavings of a certain thickness. At the same time, it is considered that in metal structures of excavators there are no stress jumps from the bucket collision with individual pieces of rock, and cyclic loads are related only to the loading and unloading cycle of the bucket. Studies have shown that in cyclic loading of metal structures, the bucket collides with each piece of rock. The magnitude of voltage jump depends on the size of rock piece. Presently, theoretical calculation of stresses in metal structures of excavators is carried out without taking into account the concentration of stresses in zones of welding defects and this gives underestimated stresses. Studies have also shown that in zones with defects, the stresses can differ several times from nominal stresses.

  3. Static Behaviour of Bucket Foundations

    DEFF Research Database (Denmark)

    Larsen, Kim André

    as well as large-scale tests on bucket foundations subjected to low vertical load are performed during this work. Numerical simulations of the tests performed are carried out using the Mohr Coulomb material model and the commercial finite element code ABAQUS. Based on the present work, the finite element......One new foundation concept in relation to offshore wind turbines is bucket foundations. The concept is known from the oil and gas industry, though the load conditions here are significantly different. The bucket foundation can be used as monopod or e.g. tripod foundations for offshore wind turbines....... The monopod concept is investigated in this thesis, regarding the static behaviour from loads relevant to offshore wind turbines. The main issue in this concept is the rotational stiffness of the foundation and the combined capacity dominated by moments. The vertical bearing capacity of bucket foundations...

  4. Reducing Extra-Terrestrial Excavation Forces with Percussion

    Science.gov (United States)

    Mueller, Robert; Schuler, Jason M.; Smith, Jonathan Drew; Nick, Andrew J.; Lippitt, Thomas

    2012-01-01

    High launch costs and mission requirements drive the need for low mass excavators with mobility platforms, which in turn have little traction and excavation reaction capacity in low gravity environments. This presents the need for precursor and long term future missions with low mass robotic mining technology to perform In-Situ Resource Utilization (ISRU) tasks. This paper discusses a series of experiments that investigate the effectiveness of a percussive digging device to reduce excavation loads and thereby the mass of the excavator itself. A percussive mechanism and 30" wide pivoting bucket were attached at the end of the arm simulating a basic backhoe with a percussion direction tangent to the direction of movement. Impact energies from 13.6J to 30.5J and frequencies from 0 BPM to 700 BPM were investigated. A reduction in excavation force of as much as 50% was achieved in this experimental investigation.

  5. Characteristic Behavior of Bucket Foundations

    DEFF Research Database (Denmark)

    Barari, Amin

    engineering experiments to gain insight into the behavior of offshore bucket foundations, and development of methods to improve the study of infiltration intounsaturated soils, an important problem in geo-environmental engineering. The outcomes of the research have the potential to directly or indirectly...... reduce the risks and costsrelated to offshore geotechnics. The thesis examines: 1.Characteristic Behavior of Bucket Foundations 2. Modeling of Water Flow through Porous Media The outcomes of each of the research contributions are summarized in four research articles, either directly or indirectly...

  6. Characteristic Behavior of Bucket Foundations

    DEFF Research Database (Denmark)

    Barari, Amin

    the design of offshore wind turbine foundations. The work was divided into two main research efforts: geotechnical engineering experiments to gain insight into the behavior of offshore bucket foundations, and development of methods to improve the study of infiltration into unsaturated soils, an important...

  7. Lightweight Robotic Excavation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Robust, lightweight, power-efficient excavation robots are mission enablers for lunar outposts and surface systems. Lunar excavators of this type cost-effectively...

  8. Second Stage Turbine Bucket Airfoil.

    Science.gov (United States)

    Xu, Liming; Ahmadi, Majid; Humanchuk, David John; Moretto, Nicholas; Delehanty, Richard Edward

    2003-05-06

    The second-stage buckets have airfoil profiles substantially in accordance with Cartesian coordinate values of X, Y and Z set forth in inches in Table I wherein Z is a perpendicular distance from a plane normal to a radius of the turbine centerline and containing the X and Y values with the Z value commencing at zero in the X, Y plane at the radially innermost aerodynamic section of the airfoil and X and Y are coordinate values defining the airfoil profile at each distance Z. The X, Y and Z values may be scaled as a function of the same constant or number to provide a scaled-up or scaled-down airfoil section for the bucket.

  9. Buckets of Higgs and tops

    Energy Technology Data Exchange (ETDEWEB)

    Buckley, Matthew R. [Center for Particle Astrophysics, Fermi National Accelerator Laboratory,Batavia, IL (United States); Department of Physics and Astronomy, Rutgers University,Piscataway, NJ (United States); Plehn, Tilman; Schell, Torben [Institut für Theoretische Physik, Universität Heidelberg,Heidelberg (Germany); Takeuchi, Michihisa [Theoretical Particle Physics and Cosmology Group, Department of Physics,King’s College London, London WC2R 2LS (United Kingdom)

    2014-02-28

    We show that associated production of a Higgs with a top pair can be observed in purely hadronic decays. Reconstructing the top quarks in the form of jet buckets allows us to control QCD backgrounds as well as signal combinatorics. The background can be measured from side bands in the reconstructed Higgs mass. We back up our claims with a detailed study of the QCD event simulation, both for the signal and for the backgrounds.

  10. Focal Choroidal Excavation.

    Science.gov (United States)

    Cebeci, Zafer; Bayraktar, Şerife; Oray, Merih; Kır, Nur

    2016-12-01

    Focal choroidal excavation is a choroidal pit that can be detected by optical coherence tomography. Central serous chorioretinopathy, choroidal neovascularization and polypoidal choroidal vasculopathy are pathologies associated with focal choroidal excavation. In this article, we present the follow-up and treatment outcomes of three eyes of two patients with focal choroidal excavation.

  11. Determination of Critical Rock Mass in a Bucket of a Dinting Loader

    Science.gov (United States)

    Remiorz, Eryk

    2017-09-01

    The extraction of hard coal deposits lying in increasing depth causes significant problems with maintenance of roadways (maingates, tailgates, etc.). The reduction of the cross section of such excavations, caused by the floor upheaval, leads to the occurrence of many problems with transport and ventilation. Dinting loaders are employed to restore the original size of roadways tightened due to the activity of adverse stresses occurring in the rock mass. These are tracked machines, usually with small width of about 1 m. They often work in roadways with high longitudinal and lateral inclination, as a result of which they are especially susceptible to overturning. The article presents a mathematical model allowing to determine the critical mass of broken rock in a bucket. The model also allows to determine spatial coordinates of a dinting loader's centre of gravity depending on temporary position of movable elements of the loader such as a turntable, boom, coupler and bucket, and depending on the level of loading the bucket with broken rock. It also enables to determine critical angles of the roadways' longitudinal and lateral inclination. The outcomes of computer studies of variations in the position of the loader's centre of gravity depending on deflection angles of moving elements of the loader and the mass of broken rock in the bucket are also presented. Variability ranges of spatial coordinates of the centre of gravity of the loader are also established and examples are given for values of the critical mass of broken rock in the bucket.

  12. Instability of Bucket Foundations during Installation

    DEFF Research Database (Denmark)

    Madsen, Søren; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo

    The bucket foundation is an upcoming technology for offshore wind turbines. The bucket foundation is a large cylindrical monopod foundation constructed as a thin steel shell structure. A bucket foundation does not require heavy installation equipment since it is installed by suction forces....... The combination of a thin shell structure and suction forces leads to the fact that instability, in form of buckling, becomes a crucial issue during installation. The hydrostatic buckling pressure of the bucket foundation is addressed using three-dimensional, non-linear finite element analysis. The results...

  13. Holey buckets! Monitoring plot-scale runoff

    Science.gov (United States)

    Rupp, D. E.; Stewart, R. D.; Abou Najm, M. R.; Selker, J. S.; Selker, F.; Van De Giesen, N.

    2011-12-01

    Measurement of plot-scale surface runoff is commonly achieved by diverting flow through a flume or tipping bucket system, or into a storage tank, such as bucket. The principle advantages of the "bucket method" are relative simplicity and low cost. The principle drawback is that the bucket requires frequent emptying during heavy runoff, unless the bucket volume is very large. As a solution to the problem of emptying the bucket while still retaining the properties of simplicity and economy, we used a holey bucket. Our "bucket" is vertical 4"-diameter ABS pipe, sealed at the bottom, and with holes along the side of the pipe. A screen in the pipe catches debris that could block the holes. The holes' diameters and locations were chosen to capture both low (100 L min-1) flows. Runoff is diverted into the top of the pipe. The runoff rate is determined from the water level and the rate of change in water level: the water level gives the flow rate out of the submerged holes (using Torricelli's Law) and the change in water level gives the rate of change in storage in the pipe. The runoff is calculated as the sum of the hole discharge and the rate of change in storage. A calibration parameter is applied to account for departures from assumptions of the theory. The design is currently being utilized to monitor runoff from experimental plots on a rural hillslope in Chile.

  14. Scour and Scour Protection for Bucket Foundations

    DEFF Research Database (Denmark)

    Larsen, Brian Juul; Frigaard, Peter

    A test programme has been performed to determine the scour around a bucket foundation for an offshore windturbine. furthermore the necessary scour protection has been investigated.......A test programme has been performed to determine the scour around a bucket foundation for an offshore windturbine. furthermore the necessary scour protection has been investigated....

  15. Vitelliform focal choroidal excavation.

    Science.gov (United States)

    Or, Chris; Forooghian, Farzin

    2014-05-30

    Focal choroidal excavations (FCE) are characterized by foveal or perifoveal choroid excavations seen on optical coherence tomography (OCT). The authors report a case of FCE associated with a vitelliform lesion within the excavation. A case of FCE associated with a small vitelliform lesion has been described previously, but the larger extent of the vitelliform lesion observed in the current case has not been previously reported. This may represent a novel category of FCE, vitelliform focal choroidal excavation, in which deposition of vitelliform material is associated with its development. Copyright 2014, SLACK Incorporated.

  16. Discrete Element Modeling for Mobility and Excavation

    Science.gov (United States)

    Knuth, M. A.; Hopkins, M. A.

    2011-12-01

    The planning and completion of mobility and excavation efforts on the moon requires a thorough understanding of the planetary regolith. In this work, a discrete element method (DEM) model is created to replicate those activities in the laboratory and for planning mission activities in the future. The crux of this work is developing a particle bed that best replicates the regolith tool/wheel interaction seen in the laboratory. To do this, a DEM geotechnical triaxial strength cell was created allowing for comparison of laboratory JSC-1a triaxial tests to DEM simulated soils. This model relies on a triangular lattice membrane covered triaxial cell for determining the macroscopic properties of the modeled granular material as well as a fast and efficient contact detection algorithm for a variety of grain shapes. Multiple grain shapes with increasing complexity (ellipsoid, poly-ellipsoid and polyhedra) have been developed and tested. This comparison gives us a basis to begin scaling DEM grain size and shape to practical values for mobility and excavation modeling. Next steps include development of a DEM scoop for percussive excavation testing as well as continued analysis of rover wheel interactions using a wide assortment of grain shape and size distributions.

  17. Crane and Excavator Operator.

    Science.gov (United States)

    Marine Corps Inst., Washington, DC.

    Developed as part of the Marine Corps Institute (MCI) correspondence training program, this course on crane and excavator operation is designed to enable the crane and excavator operator to perform his/her duties more proficiently. Introductory materials include specific information for MCI students, a course introduction, and a study guide…

  18. Bucket Foundation Response Under Various Displacement Rates

    DEFF Research Database (Denmark)

    Vaitkunaite, Evelina; Nielsen, Benjaminn Nordahl; Ibsen, Lars Bo

    2016-01-01

    The present testing program aims at showing the pore pressure response around a bucket foundation skirt as well as the load and displacement change due to ten different displacement rates. Research findings are useful for a numerical model calibration focusing on the design of the upwind foundation...... in a multi-bucket foundation system. The foundation model is at a scale of approximately 1:20 prototype foundation size. The tests are performed in a pressure tank with the foundation model installed in dense sand. Based on the data, the conclusion is that the bucket foundation design in a storm case should...

  19. Principles of Mechanical Excavation

    Energy Technology Data Exchange (ETDEWEB)

    Lislerud, A. [Tamrock Corp., Tampere (Finland)

    1997-12-01

    Mechanical excavation of rock today includes several methods such as tunnel boring, raiseboring, roadheading and various continuous mining systems. Of these raiseboring is one potential technique for excavating shafts in the repository for spent nuclear fuel and dry blind boring is promising technique for excavation of deposition holes, as demonstrated in the Research Tunnel at Olkiluoto. In addition, there is potential for use of other mechanical excavation techniques in different parts of the repository. One of the main objectives of this study was to analyze the factors which affect the feasibility of mechanical rock excavation in hard rock conditions and to enhance the understanding of factors which affect rock cutting so as to provide an improved basis for excavator performance prediction modeling. The study included the following four main topics: (a) phenomenological model based on similarity analysis for roller disk cutting, (b) rock mass properties which affect rock cuttability and tool life, (c) principles for linear and field cutting tests and performance prediction modeling and (d) cutter head lacing design procedures and principles. As a conclusion of this study, a test rig was constructed, field tests were planned and started up. The results of the study can be used to improve the performance prediction models used to assess the feasibility of different mechanical excavation techniques at various repository investigation sites. (orig.). 21 refs.

  20. Fixing the Hole in My Bucket

    Science.gov (United States)

    Nitkewicz, Edward J.

    2011-01-01

    Like many people, the author has spent the better part of his life fashioning a list of places he wanted to go and things he wanted to do. Because he is a typical American male, his "Bucket List" is mostly populated by sporting venues he wants to visit and sporting events he wants to witness. Sharing his "Bucket List" with his son would be a gift…

  1. Bucket foundations under lateral cyclic loading

    DEFF Research Database (Denmark)

    Foglia, Aligi

    To enable a prosperous development of offshore wind energy, economically feasible technologies must be developed. The monopod bucket foundation is likely to become a cost-effective sub-structure for offshore wind turbines and has the potential to make offshore wind more cost-competitive in the en......To enable a prosperous development of offshore wind energy, economically feasible technologies must be developed. The monopod bucket foundation is likely to become a cost-effective sub-structure for offshore wind turbines and has the potential to make offshore wind more cost......-competitive in the energy market. This thesis addresses issues concerning monopod bucket foundations in the hope of providing tools and ideas that could be used to optimize the design of this sub-structure. The work is focussed on the behaviour of bucket foundations under lateral cyclic loading. Other related...... and propaedeutic topics, such as bucket foundations under transient lateral loading and under monotonic lateral loading, are also investigated. All the scientific work is fundamentally based on small-scale experimental tests of bucket foundations in dense water-saturated sand. The most important scientific...

  2. Bucket transport of energetic ions in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Yakovenko, Yu.V., E-mail: yakovenko@kinr.kiev.ua [Institute for Nuclear Research, Prospekt Nauky 47, Kyiv 03680 (Ukraine); National University of Kyiv Mohyla Academy, Vul. Skovorody 2, Kyiv 04070 (Ukraine); Burdo, O.S.; Kolesnichenko, Ya.I.; Tyshchenko, M.H. [Institute for Nuclear Research, Prospekt Nauky 47, Kyiv 03680 (Ukraine)

    2015-09-25

    The so-called “bucket transport” of energetic ions — the spatial mixing of these ions due to spatial displacement of resonances — is studied with special attention to quasi-steady-state magnetic perturbations. A Hamiltonian formalism suitable to the case when the resonance displacement results from the collisional slowing down of the particles and the temporal evolution of the safety factor profile is suggested. The energy flux produced due to the bucket transport is shown to be considerable in configurations with low shear. It is shown that the bucket transport flux associated with magnetic islands tends to be localized at some distance from the islands. The bucket transport caused by perturbations with non-zero frequencies is also discussed. - Highlights: • The bucket transport of energetic ions is the spatial mixing due to spatial displacements of resonances. • The bucket transport may be of importance when the magnetic shear is small. • The particle and energy fluxes are located apart from the magnetic islands causing the transport. • The transport due to non-zero-frequency perturbations is less sensitive to the shear and may contribute to ash removal.

  3. Buckets: Smart Objects for Digital Libraries

    Science.gov (United States)

    Nelson, Michael L.

    2001-01-01

    Current discussion of digital libraries (DLs) is often dominated by the merits of the respective storage, search and retrieval functionality of archives, repositories, search engines, search interfaces and database systems. While these technologies are necessary for information management, the information content is more important than the systems used for its storage and retrieval. Digital information should have the same long-term survivability prospects as traditional hardcopy information and should be protected to the extent possible from evolving search engine technologies and vendor vagaries in database management systems. Information content and information retrieval systems should progress on independent paths and make limited assumptions about the status or capabilities of the other. Digital information can achieve independence from archives and DL systems through the use of buckets. Buckets are an aggregative, intelligent construct for publishing in DLs. Buckets allow the decoupling of information content from information storage and retrieval. Buckets exist within the Smart Objects and Dumb Archives model for DLs in that many of the functionalities and responsibilities traditionally associated with archives are pushed down (making the archives dumber) into the buckets (making them smarter). Some of the responsibilities imbued to buckets are the enforcement of their terms and conditions, and maintenance and display of their contents.

  4. Lightweight Robotic Excavation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Lightweight robotic excavators address the need for machines that dig, collect, transport and dump lunar soil. Robust and productive small robots enable mining rich...

  5. Lunar Excavator Validation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Energid Technologies proposes to create a tool for simulation-based verification of lunar excavator designs. Energid will combine the best of 1) automatic control...

  6. Preserving the Pyramid of STI Using Buckets

    Science.gov (United States)

    Nelson, Michael L.; Maly, Kurt

    2004-01-01

    The product of research projects is information. Through the life cycle of a project, information comes from many sources and takes many forms. Traditionally, this body of information is summarized in a formal publication, typically a journal article. While formal publications enjoy the benefits of peer review and technical editing, they are also often compromises in media format and length. As such, we consider a formal publication to represent an abstract to a larger body of work: a pyramid of scientific and technical information (STI). While this abstract may be sufficient for some applications, an in-depth use or analysis is likely to require the supporting layers from the pyramid. We have developed buckets to preserve this pyramid of STI. Buckets provide an archive- and protocol-independent container construct in which all related information objects can be logically grouped together, archived, and manipulated as a single object. Furthermore, buckets are active archival objects and can communicate with each other, people, or arbitrary network services. Buckets are an implementation of the Smart Object, Dumb Archive (SODA) DL model. In SODA, data objects are more important than the archives that hold them. Much of the functionality traditionally associated with archives is pushed down into the objects, such as enforcing terms and conditions, negotiating display, and content maintenance. In this paper, we discuss the motivation, design, and implication of bucket use in DLs with respect to grey literature.

  7. Lunar Regolith Excavation Competition

    Science.gov (United States)

    Liles, Cassandra

    2009-01-01

    The Lunar Regolith Excavation Competition is a new competition that needs graphics, logos, rules, as well as an arena. Although this is the first year of the competition, the competition is modeled after an existing competition, the Centennial Lunar Excavator Challenge. This competition however is aimed at college students. This makes the challenge identifying key aspects of the original competition and modeling them to fit into an easier task, and creating exciting advertisement that helps encourage participation. By using a youth focus group, young insight, as well as guiding advice from experts in the field, hopefully an arena can be designed and built, rules can be molded and created to fit, and alluring graphics can be printed to bring about a successful first year of the Lunar Regolith Excavation Competition.

  8. Mobile continuous lunar excavation

    Science.gov (United States)

    Paterson, John L.

    1992-01-01

    A novel approach to the concept of lunar mining and the use of in situ oxygen, metallics, and ceramics is presented. The EVA time required to set up, relocate, and maintain equipment, as well as the cost per pound of shipping the mining and processing equipment to the moon are considered. The proposed soil fracturing/loading mechanisms are all based loosely on using the Apollo Lunar Roving Vehicle (LRV) Frame. All use motor driven tracks for mobility in the forward/reverse and left/right direction. All mechanisms employ the concept of rototillers which are attached to a gantry which, through the use of motor-driven lead screws, provide the rototillers with an up/down capability. A self-reactant excavator, a local mass enhanced excavator, and a soil reactant excavator are illustrated.

  9. Barrier bucket experiment at the AGS

    Directory of Open Access Journals (Sweden)

    M. Fujieda

    1999-12-01

    Full Text Available A barrier bucket experiment with two dedicated barrier cavities was performed at the Brookhaven AGS. One of the barrier cavities was a magnetic alloy (MA–loaded cavity and the other was a ferrite-loaded cavity. They generated a single sine wave with a peak voltage of 40 kV at a repetition rate of 351 kHz. A barrier rf system was established with these cavities and five bunches from the AGS booster were accumulated. A total of 3×10^{13} protons were stored without beam loss, and were successfully rebunched and accelerated. The longitudinal emittance growth was observed during accumulation by the barrier bucket, the blowup factor of which was about 3. The longitudinal mismatch between the rf bucket and the beam bunch was the main reason for the emittance growth. The potential distortions by beam loading of the ferrite cavity and the overshooting voltage of the MA cavity disturbed the smooth debunching.

  10. Word wheels

    CERN Document Server

    Clark, Kathryn

    2013-01-01

    Targeting the specific problems learners have with language structure, these multi-sensory exercises appeal to all age groups including adults. Exercises use sight, sound and touch and are also suitable for English as an Additional Lanaguage and Basic Skills students.Word Wheels includes off-the-shelf resources including lesson plans and photocopiable worksheets, an interactive CD with practice exercises, and support material for the busy teacher or non-specialist staff, as well as homework activities.

  11. Towards international excavation tasks

    NARCIS (Netherlands)

    Ike, Paul

    1999-01-01

    Over the last twenty years social opposition to mineral excavation has increased to such an extent in the densely populated Netherlands, that it is getting extremely difficult to discover new sites for quarrying coarse sand for concrete. While the Dutch government has attempted for many years to

  12. Prototype bucket foundation for wind turbines

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Liingaard, Morten

    The first full scale prototype bucket foundation for wind turbines has been installed in October 2002 at Aalborg University offshore test facility in Frederikshavn, Denmark. The suction caisson and the wind turbine have been equipped with an online monitoring system, consisting of 15 accelerometers...

  13. Monopod Bucket Foundations Under Cyclic Lateral Loading

    DEFF Research Database (Denmark)

    Foglia, Aligi; Ibsen, Lars Bo

    2016-01-01

    The monopod bucket foundation has the potential to become a cost-reducing substructure for offshore wind turbines. To avoid problems during the energy converter operation, the long-term effect of cyclic loading must be considered in the design of the foundation. In this paper, a 1-g testing rig...

  14. Monopod bucket foundations under cyclic lateral loading

    DEFF Research Database (Denmark)

    Foglia, Aligi; Ibsen, Lars Bo

    The monopod bucket foundation can be a cost-reducing sub-structure for offshore wind turbines. To avoid problems during the turbine operation, the long-term effect of cyclic loading must be considered in the design of the foundation. In this paper a 1g testing rig is adopted to extend the knowledge...

  15. From Newton's bucket to rotating polygons

    DEFF Research Database (Denmark)

    Bach, B.; Linnartz, E. C.; Vested, Malene Louise Hovgaard

    2014-01-01

    and move from a rigidly rotating 'Newton's bucket' flow to one where bottom and cylinder wall are rotating oppositely and the surface is strongly turbulent but flat on average. Between those two extremes, we find polygonal states for which the rotational symmetry is spontaneously broken. We investigate...

  16. Excavator Design Validation

    Science.gov (United States)

    Pholsiri, Chalongrath; English, James; Seberino, Charles; Lim, Yi-Je

    2010-01-01

    The Excavator Design Validation tool verifies excavator designs by automatically generating control systems and modeling their performance in an accurate simulation of their expected environment. Part of this software design includes interfacing with human operations that can be included in simulation-based studies and validation. This is essential for assessing productivity, versatility, and reliability. This software combines automatic control system generation from CAD (computer-aided design) models, rapid validation of complex mechanism designs, and detailed models of the environment including soil, dust, temperature, remote supervision, and communication latency to create a system of high value. Unique algorithms have been created for controlling and simulating complex robotic mechanisms automatically from just a CAD description. These algorithms are implemented as a commercial cross-platform C++ software toolkit that is configurable using the Extensible Markup Language (XML). The algorithms work with virtually any mobile robotic mechanisms using module descriptions that adhere to the XML standard. In addition, high-fidelity, real-time physics-based simulation algorithms have also been developed that include models of internal forces and the forces produced when a mechanism interacts with the outside world. This capability is combined with an innovative organization for simulation algorithms, new regolith simulation methods, and a unique control and study architecture to make powerful tools with the potential to transform the way NASA verifies and compares excavator designs. Energid's Actin software has been leveraged for this design validation. The architecture includes parametric and Monte Carlo studies tailored for validation of excavator designs and their control by remote human operators. It also includes the ability to interface with third-party software and human-input devices. Two types of simulation models have been adapted: high-fidelity discrete

  17. Scour properties of mono bucket foundation

    DEFF Research Database (Denmark)

    Stroescu, Ionut Emanuel; Frigaard, Peter Bak

    2016-01-01

    Field experience proved that the Mono Bucket Foundations (MBFs) have good response against scour development. Moreover, the ratio between large diameter (bucket lid) and the small diameter (shaft tower) is the driving parameter for the process of erosion/backfill, like scour protection diameter...... the North Sea and compared with lab tests. The results showed a sensibility to the misalignment height comparable with the berm height of the scour protection on traditional monopiles leading to edge scour. Design improvements to limit the scour and increase backfill have been found. The experimental...... analysis compared with real surveys and existing studies showed good agreements. Scour protection based on collar solution shows high efficiency when scour protection should be required. The paper demonstrates good agreement between field measurements and small-scale studies. The unique value of the field...

  18. Third-stage turbine bucket airfoil

    Science.gov (United States)

    Pirolla, Peter Paul; Siden, Gunnar Leif; Humanchuk, David John; Brassfield, Steven Robert; Wilson, Paul Stuart

    2002-01-01

    The third-stage buckets have airfoil profiles substantially in accordance with Cartesian coordinate values of X, Y and Z set forth in inches in Table I wherein Z is a perpendicular distance from a plane normal to a radius of the turbine centerline and containing the X and Y values with the Z value commencing at zero in the X, Y plane at the radially innermost aerodynamic section of the airfoil and X and Y are coordinates defining the airfoil profile at each distance Z. The X, Y and Z values may be scaled as a function of the same constant or number to provide a scaled-up or scaled-down airfoil section for the bucket.

  19. Kicking the Bucket: It's All about Living

    Science.gov (United States)

    Perry, Kekailoa

    2013-01-01

    In Hawai'i there is a myth known as the alamihi crab syndrome. The myth is a creation of foreign origin used to explain a Western worldview of Hawaiians. It is deployed to explain everything from the 1893 overthrow of the monarchy to the reason why Hawaiians can never better their lives. Crabs in a bucket have a tendency to struggle and fight to…

  20. Thermal Insulation System for Large Flame Buckets

    Science.gov (United States)

    Callens, E. Eugene, Jr.; Gamblin, Tonya Pleshette

    1996-01-01

    The objective of this study is to investigate the use of thermal protection coatings, single tiles, and layered insulation systems to protect the walls of the flame buckets used in the testing of the Space Shuttle Main Engine, while reducing the cost and maintenance of the system. The physical behavior is modeled by a plane wall boundary value problem with a convective frontface condition and a backface condition designed to provide higher heat rates through the material.

  1. Optimal Design of Stiffeners for Bucket Foundations

    DEFF Research Database (Denmark)

    Courtney, William Tucker; Stolpe, Mathias; Buhl, Thomas

    2015-01-01

    The potential for structural optimization of the bucket foundation’s outer stiffeners is investigated using commercial optimization software. In order to obtain the optimal design both shape and topology optimization problems are formulated and solved using the structural optimization software To...... led to a new design concept with a mass reduction of 25.5% (19.2 tons) when compared to the original design....

  2. MANAJEMEN BANDWIDTH MENGGUNAKAN METODE HIERARCHICAL TOKEN BUCKET

    Directory of Open Access Journals (Sweden)

    Lisnawita Lisnawita

    2016-02-01

    Full Text Available AbstrakInternet pada era sekarang ini adalah salah satu kebutuhan manusia, karena itu dibutuhkan bandwidth yang besar supaya bisa download atau upload dengan cepat, tapi karena keterbatasan bandwidth yang ada, maka perlu Manajemen bandwidth dengan metode Hierarchical Token Bucket(HTB, metode ini banyak digunakan untuk mengatasi permasalahan pada koneksi Internet, memaksimalkan penggunaan bandwidth sehingga semua user dapat menggunakan bandwidth secara adil dan semua user mendapatkan kenyamanan dan kepuasan ketika browsing, Penelitian ini menggunakan metode Hierarchical Token Bucket(HTB yaitu salah satu metode yang dirancang untuk bisa melakukan manajemen bandwidth dengan baik, dimana algoritma ini menerapkan disiplin antrian yang mempunyai kelebihan dalam pembatasan trafik pada tiap level maupun klasifikasi, sehingga bandwidth yang tidak dipakai oleh level yang tinggi dapat digunakan atau dibagi oleh level yang lebih rendah.Kata Kunci: Bandwidth,Manajemen Bandwidth,HTBAbstractInternet in this era is one of human needs, because it takes a large bandwid thin order to download or upload quickly,but due to the limited bandwidth available, the necessary management bandwidth by using Hierarchical Token Bucket(HTB, this method is widely used for solve the problems on Internet connections, maximizing the use of bandwidth so that all users can use the bandwidth fairly and users get the comfort and satisfaction when browsing, this researchusing Hierarchical Token Bucket(HTB is one method that is designed to be able to perform bandwidth management,where the algorithm queuing discipline which have advantage sin traffic restriction soneach level and classification, so that the bandwidth is not used by a high level can be used or share by a low levelKeywords: Bandwidth, Bandwidth Management, HTB

  3. Safety excavation; Seguranca em escavacoes

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Walter Manoel [TRANSPETRO - PETROBRAS Transporte S.A., Rio de Janeiro, RJ (Brazil)

    2003-07-01

    In the construction and maintenance services of buried pipelines, the excavation is the activity that contains larger risk, could cause serious accidents. Norms, procedures and technical articles, national and international goods, should be followed for legal and technical aspects. This paper - Safety in Excavations - has purpose to gather all the technical concepts and of safety in a document denominated Procedure of Safety Excavation, serving as instrument to systematize and control the execution of excavation services in construction civil, assembly and pipelines repairs, seeking the people, facilities and the environment's safety. (author)

  4. Testing of Axially Loaded Bucket Foundation with Applied Overburden Pressure

    DEFF Research Database (Denmark)

    Vaitkunaite, Evelina; Ibsen, Lars Bo; Nielsen, Benjaminn Nordahl

    This report analyses laboratory testing data performed with a bucket foundation model subjected to axial loading. The examinations were conducted at the Geotechnical laboratory of Aalborg University. The report aims at showing and discussing the results of the static and cyclic axial loading tests...... on the bucket foundation model. Finally, a cyclic loading interaction diagram is given that can be applied for a full-scale bucket foundation design....

  5. Thin-walled reinforcement lattice structure for hollow CMC buckets

    Energy Technology Data Exchange (ETDEWEB)

    de Diego, Peter

    2017-06-27

    A hollow ceramic matrix composite (CMC) turbine bucket with an internal reinforcement lattice structure has improved vibration properties and stiffness. The lattice structure is formed of thin-walled plies made of CMC. The wall structures are arranged and located according to high stress areas within the hollow bucket. After the melt infiltration process, the mandrels melt away, leaving the wall structure to become the internal lattice reinforcement structure of the bucket.

  6. Improved Concrete Cutting and Excavation Capabilities for Crater Repair, Phase 1

    Science.gov (United States)

    2014-04-01

    required manpower, using Caterpillar SW45 and Sw60 wheel saws and Caterpillar and Volvo excavators, respectively, in 18-in.-thick PCC pavement did not...15 3.3 Husqvarna FS 6600D walk-behind saw ..................................................................... 17 3.4 Volvo ...FS 6600D. .............................................................................................................. 18 Figure 13. Volvo EW180D

  7. Vertical Capacity of Bucket Foundations in Undrained Soil

    DEFF Research Database (Denmark)

    Barari, Amin; Ibsen, Lars Bo

    2014-01-01

    Offshore wind turbine structures are traditionally founded on gravity concrete foundations or mono-piles. Bucket foundations were developed for the offshore oil and gas industry and are now being used in wind turbine construction. The loading in this application is characterized by a vertical load...... due to the slender construction combined with horizontal forces inducing a large overturning moment. Field tests on bucket foundations were performed to gain insight into the vertical load response of bucket foundations in clay soils. The field tests were accompanied by finite element numerical...... simulations in order to provide a better understanding of the parameters influencing bucket foundation behavior....

  8. Undrained Response of Bucket Foundations to Moment Loading

    DEFF Research Database (Denmark)

    Barari, Amin; Ibsen, Lars Bo

    2012-01-01

    Bucket foundation as a large cylindrical structure that is open at the base and closed at the top, is recently being used within the offshore wind turbines projects. The bearing capacity of bucket foundations to moment loading in undrained soil is of interest particularly to the offshore...... geotechnical engineers. This paper presents the experimental and numerical results of moment loading on small scale models of bucket foundations installed on Yoldia clay. The moment loading is experienced via the horizontal forces applied to features on a tower installed on bucket foundations. Different arm...

  9. Qajaa Excavations 1981 and 1982

    DEFF Research Database (Denmark)

    Fog Jensen, Jens

    2015-01-01

    This report is an account of excavations conducted in 1981 and 1982 by Jørgen Meldgaard (1927-2007) The National Museum of Denmark at the Qajaa site in West Greenland. A total of 388 wooden objects, 255 bone artefacts, 696 lithic tools and more than 4000 flakes have been excavated and are presented...

  10. Numerical Investigation Cavitation Buckets for Hydrofoil Parametrically

    Directory of Open Access Journals (Sweden)

    Mehmet Salih KARAALİOĞLU

    2015-12-01

    Full Text Available Cavitation is a general fluid mechanics phenomenon that is appeared in system such as pumps, turbines, marine propellers and hydrofoils which induces pressure and velocity fluctuation in the fluid (Brennen, 2013. Cavitation can be defined as the formation of vapour regions due to a decrease in local pressure. Undesirable consequences which can cause a fall in the performance of a system, structural failure, production of noise and vibration, material damage, are encountered due to cavitation (Uşar, 2015. In this study, cavitation was analysed using a bucket diagram. Bucket diagram represents the cavitation behaviour of a wing, fin or propeller blade in a two dimensional sense. This diagram is plotted as a function of section (hydrofoil angle of attack (α versus section cavitation number (σ. Pressure distribution can be calculated on two dimensional geometry of hydrofoil by using BEM (Boundary Element Method and cavitation bucket diagram can be computed. The cavitation inception case and partial cavitation cases have been investigated and the results of the present BEM were successfully compared with those of given in literature in the past and each other. While a constant source-dipole panel method has been used to calculate the pressure distribution at cavitation inception case, PCPAN programme that solves the sheet type of cavity on the hydrofoil by potential based panel method, has been used to calculate pressure distribution for the cases of partial cavitation. Effects of maximum hydrofoil thickness, maximum camber and location of maximum camber on cavitation have been analyzed by means of cavitation bucklet diagrams. All results are discussed in a detailed manner.

  11. Adaptive plasticity model for bucket foundations

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Barari, Amin; Larsen, Kim A.

    2014-01-01

    Based on experimental investigations, the literature proposes different methods for modeling the behavior and capacity of foundations subjected to combined loading. Generally, two methods are used to predict the behavior of foundations: traditional approaches and hardening plasticity solutions....... The first method is only capable of determining the capacity of the foundations and not the prepeak behavior. Thus, a new strain-hardening criterion is developed by calibrating failure criteria by employing data from small-scale tests on bucket foundations subjected to static loads. The shape of the yield...

  12. Stiffness Formulation of Flexible Bucket Foundation

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Liingaard, Morten; Larsen, Kim André

    that it can be properly included and analysed in a composite structure-foundation system. The typical approach for analysing the structure-foundation system is to use a finite-element method. Such an approach is, however, inefficient and time consuming. The Elastic Macro Model describes the foundation......The response of offshore wind turbines e.g. static, eigen frequencies and eigen modes, are affected by elastic properties of the foundation and the subsoil. The Elastic Macro Model is developed to evaluate the soil-structure interaction of flexible bucket foundations for offshore wind turbines so...

  13. An Innovative Physical Model for Testing Bucket Foundations

    DEFF Research Database (Denmark)

    Foglia, Aligi; Ibsen, Lars Bo; Andersen, Lars Vabbersgaard

    2012-01-01

    Monopod bucket foundations promise to become a reliable and cost-effective solution for offshore wind turbines. In this paper, six small scale tests of a steel bucket foundation subjected to quasi-static lateral load, are presented. When conducting small scale experiments on soil, scale effects can...

  14. Thick barrier buckets using the SPS travelling wave structures

    CERN Document Server

    Bohl, T; Shaposhnikova, Elena; CERN. Geneva. SPS and LEP Division

    2000-01-01

    The barrier bucket technique has many interesting applications and has been tested in different laboratories around the world. In all these cases; specially designed, very broad band (Q = 1) cavities were installed in the ring. We used the existing travelling wave cavities in the SPS to create multi-period barrier buckets and hold the beam.

  15. Comparison of design methods for axially loaded buckets in sand

    DEFF Research Database (Denmark)

    Vaitkunaite, Evelina; Nielsen, Benjaminn Nordahl; Ibsen, Lars Bo

    2015-01-01

    A study of the present knowledge about the bucket resistance for axial loading was performed considering analytical and numerical design methods as well as physical models. A case study was performed with two bucket foundations of equal diameter, but different skirt lengths installed in dense san...

  16. Airfoil shape for a turbine bucket

    Science.gov (United States)

    Hyde, Susan Marie; By, Robert Romany; Tressler, Judd Dodge; Schaeffer, Jon Conrad; Sims, Calvin Levy

    2005-06-28

    Third stage turbine buckets have airfoil profiles substantially in accordance with Cartesian coordinate values of X, Y and Z set forth Table I wherein X and Y values are in inches and the Z values are non-dimensional values from 0 to 0.938 convertible to Z distances in inches by multiplying the Z values by the height of the airfoil in inches. The X and Y values are distances which, when connected by smooth continuing arcs, define airfoil profile sections at each distance Z. The profile sections at each distance Z are joined smoothly to one another to form a complete airfoil shape. The X and Y distances may be scalable as a function of the same constant or number to provide a scaled up or scaled down airfoil section for the bucket. The nominal airfoil given by the X, Y and Z distances lies within an envelop of .+-.0.150 inches in directions normal to the surface of the airfoil.

  17. Wheel inspection system environment.

    Science.gov (United States)

    2008-11-18

    International Electronic Machines Corporation (IEM) has developed and is now marketing a state-of-the-art Wheel Inspection System Environment (WISE). WISE provides wheel profile and dimensional measurements, i.e. rim thickness, flange height, flange ...

  18. Three-Wheel Brush-Wheel Sampler

    Science.gov (United States)

    Duckworth, Geoffrey A.; Liu, Jun; Brown, Mark G.

    2010-01-01

    A new sampler is similar to a common snow blower, but is robust and effective in sample collection. The brush wheels are arranged in a triangle shape, each driven by a brushless DC motor and planetary gearhead embedded in the wheel shaft. Its speed can be varied from 800 - 2,000 rpm, depending on the surface regolith resistance. The sample-collecting flow path, and internal features, are designed based on flow dynamics, and the sample-collecting rates have consistently exceeded the requirement under various conditions that span the range of expected surface properties. The brush-wheel sampler (BWS) is designed so that the flow channel is the main body of the apparatus, and links the brush-wheel assembly to the sample canister. The combination of the three brush wheels, the sample flow path, and the canister location make sample collection, storage, and transfer an easier task.

  19. Buckling of Bucket Foundations During Installation

    DEFF Research Database (Denmark)

    Madsen, Søren

    There is a great politically will to expand the green energy market in these times. A proven green technology is wind turbines. Wind turbines have been installed in great numbers on land over the last decades. However, the current development in wind turbine design leads to larger turbine sizes...... in order to reduce the cost of energy. This limits the on land application due to transportation limitations and unwillingness from prospect neighbours. Thus, offshore wind energy started developing over the last couple of years. Although installing the wind turbines offshore resolves the before men tioned...... issues, it brings up the cost of energy mainly due to increased installation and maintenance costs. A very large part—up to 30–50% using current technology—of the installation cost origins from the expenses related to the installation of foundations. A new foundation concept—the bucket foundation...

  20. Multispectral imaging using a single bucket detector

    CERN Document Server

    Bian, Liheng; Situ, Guohai; Li, Ziwei; Chen, Feng; Dai, Qionghai

    2015-01-01

    Current multispectral imagers suffer from low photon efficiency and limited spectrum range. These limitations are partially due to the technological limitations from array sensors (CCD or CMOS), and also caused by separative measurement of the entries/slices of a spatial-spectral data cube. Besides, they are mostly expensive and bulky. To address above issues, this paper proposes to image the 3D multispectral data with a single bucket detector in a multiplexing way. Under the single pixel imaging scheme, we project spatial-spectral modulated illumination onto the target scene to encode the scene's 3D information into a 1D measurement sequence. Conventional spatial modulation is used to resolve the scene's spatial information. To avoid increasing requisite acquisition time for 2D to 3D extension of the latent data, we conduct spectral modulation in a frequency-division multiplexing manner in the speed gap between slow spatial light modulation and fast detector response. Then the sequential reconstruction falls...

  1. 18 CFR 1304.303 - Channel excavation.

    Science.gov (United States)

    2010-04-01

    ... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Channel excavation... Activities on TVA Flowage Easement Shoreland § 1304.303 Channel excavation. (a) Channel excavation of... encourage owners of flowage easement property to adopt the standards for channel excavation applicable to...

  2. Laser cooling of fast stored ions in barrier buckets

    CERN Document Server

    Eisenbarth, U; Grieser, M; Grimm, R; Lauer, I; Lenisa, P; Luger, V; Mudrich, M; Schätz, T; Schramm, U; Schwalm, D; Weidemüller, M

    2000-01-01

    We apply novel bunch forms for efficient laser cooling of fast stored ion beams at the Heidelberg Test Storage Ring. sup 9 Be sup + ions are longitudinally confined in barrier buckets providing free motion of the cooled ions inside the bucket (quasi-coasting beam). The implementation of laser cooling in barrier buckets is described, and longitudinal dynamics of laser cooling is compared to electron cooling. With laser cooling, longitudinal temperatures far below 1 K are reached, corresponding to a momentum spread of DELTA p/p<10 sup - sup 6. When the thermal energy becomes sufficiently small, significant modifications of the ion distribution due to space-charge effects are observed.

  3. Improved Concrete Cutting and Excavation Capabilities for Crater Repair Phase 2

    Science.gov (United States)

    2015-05-01

    than the goal of 1 ft/min. The SW60 wheel saw was the only option tested for saw cutting 24-in.-thick PCC to full depth. • The Volvo EW180D...excavator with the Volvo HB1400 moil point hammer was the most efficient technology for breaking up the 18- and 24-in.-thick PCC and required far less...time than the goal of 16 min per repair slab. The Volvo EW180D excavator with the Volvo HB1400 chisel point hammer was also capable of requiring less

  4. Effect of embedment on the plastic behaviour of Bucket Foundations

    DEFF Research Database (Denmark)

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

    2015-01-01

    studies have indicated the possibility of defining foundation response using plasticity theory. Results of multiple loading tests addressing the effect of embedment on the strain-hardening behavior of shallow bucket foundations under combined loading are reported. The kinematic mechanisms accompanying pre......-failure are presented. It is argued that the drained capacity of offshore bucket foundations and the ratio of plastic increments are largely influenced by embedment depth and the preload ratio V/Vpeak....

  5. SLOPE STABILITY EVALUATION AND EQUIPMENT SETBACK DISTANCES FOR BURIAL GROUND EXCAVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    MCSHANE DS

    2010-03-25

    After 1970 Transuranic (TRU) and suspect TRU waste was buried in the ground with the intention that at some later date the waste would be retrieved and processed into a configuration for long term storage. To retrieve this waste the soil must be removed (excavated). Sloping the bank of the excavation is the method used to keep the excavation from collapsing and to provide protection for workers retrieving the waste. The purpose of this paper is to document the minimum distance (setback) that equipment must stay from the edge of the excavation to maintain a stable slope. This evaluation examines the equipment setback distance by dividing the equipment into two categories, (1) equipment used for excavation and (2) equipment used for retrieval. The section on excavation equipment will also discuss techniques used for excavation including the process of benching. Calculations 122633-C-004, 'Slope Stability Analysis' (Attachment A), and 300013-C-001, 'Crane Stability Analysis' (Attachment B), have been prepared to support this evaluation. As shown in the calculations the soil has the following properties: Unit weight 110 pounds per cubic foot; and Friction Angle (natural angle of repose) 38{sup o} or 1.28 horizontal to 1 vertical. Setback distances are measured from the top edge of the slope to the wheels/tracks of the vehicles and heavy equipment being utilized. The computer program utilized in the calculation uses the center of the wheel or track load for the analysis and this difference is accounted for in this evaluation.

  6. Bucket shaking stops bunch dancing in Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Burov, A.; Tan, C.Y.; /Fermilab

    2011-03-01

    Bunches in Tevatron are known to be longitudinally unstable: their collective oscillations, also called dancing bunches, persist without any signs of decay. Typically, a damper is used to stop these oscillations, but recently, it was theoretically predicted that the oscillations can be stabilized by means of small bucket shaking. Dedicated measurements in Tevatron have shown that this method does stop the dancing. According to predictions of Refs. [2,3], the flattening of the bunch distribution at low amplitudes should make the bunch more stable against LLD. An experiment has been devised to flatten the distribution by modulating the RF phase at the low-amplitude synchrotron frequency for a few degrees of amplitude. These beam studies show that stabilisation really happens. After several consecutive shakings, the dancing disappears and the resulting bunch profile becomes smoother at the top. Although not shown in this report, sometimes a little divot forms at the centre of the distribution. These experiments confirm that resonant RF shaking flattens the bunch distribution at low amplitudes, and the dancing stops.

  7. Why Wheels Work.

    Science.gov (United States)

    Stepp, Richard D.

    1982-01-01

    Discusses how the wheel works. The inherent mechanical advantage of wheel-and-axle system is that it reduced the distance the load-bearing surfaces have to slip relative to one another when the whole apparatus advances some given distance reducing (with leverage) the force needed to propel the system. (Author/JN)

  8. Reimagining the Color Wheel

    Science.gov (United States)

    Snyder, Jennifer

    2011-01-01

    Color wheels are a traditional project for many teachers. The author has used them in art appreciation classes for many years, but one problem she found when her pre-service art education students created colored wheels was that they were boring: simple circles, with pie-shaped pieces, which students either painted or colored in. This article…

  9. Reinventing the Wheel

    Science.gov (United States)

    Kim, Mihyeon; Bland, Lori C.; Chandler, Kimberley

    2009-01-01

    "The Wheel of Scientific Investigation and Reasoning" (Kramer 1987; Paul and Binker 1992) is a graphic representation of the scientific investigative process. The scientific process is depicted in a wheel rather than in a list because "the process of scientific inquiry can begin from any stage, and that stage may be revisited as often as the…

  10. Low-energy Planetary Excavator (LPE) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC is developing an innovative Low-energy Planetary Excavator (LPE) to excavate in situ regolith, ice-regolith mixes, and a variety of other geologic materials...

  11. Low-energy Planetary Excavator (LPE) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC proposes to develop an innovative Low-energy Planetary Excavator (LPE) to excavate in situ regolith, ice-regolith mixes, and a variety of other geologic...

  12. A Nontoxic Barlow's Wheel

    Science.gov (United States)

    Daffron, John A.; Greenslade, Thomas B.

    2015-01-01

    Barlow's wheel has been a favorite demonstration since its invention by Peter Barlow (1776-1862) in 1822.1 In the form shown in Fig. 1, it represents the first electric motor. The interaction between the electric current passing from the axle of the wheel to the rim and the magnetic field produced by the U-magnet produces a torque that turns the wheel. The original device used mercury to provide electrical contact to the rim, and the dangers involved with the use of this heavy metal have caused the apparatus to disappear from the lecture hall.

  13. The Reaction Wheel Pendulum

    CERN Document Server

    Block, Daniel J; Spong, Mark W

    2007-01-01

    This monograph describes the Reaction Wheel Pendulum, the newest inverted-pendulum-like device for control education and research. We discuss the history and background of the reaction wheel pendulum and other similar experimental devices. We develop mathematical models of the reaction wheel pendulum in depth, including linear and nonlinear models, and models of the sensors and actuators that are used for feedback control. We treat various aspects of the control problem, from linear control of themotor, to stabilization of the pendulum about an equilibrium configuration using linear control, t

  14. Cost-Effective Mass Production of Mono Bucket Foundations

    DEFF Research Database (Denmark)

    Gres, Szymon; Nielsen, Søren Andreas; Fejerskov, Morten

    2015-01-01

    No recognized procedures exist for the Mono Bucket Foundation design, which is an obstruction for mass customization/production and industrialization in relation to certifying authorities. This paper presents the outcome of on-going research and development program that provides solution for inno......No recognized procedures exist for the Mono Bucket Foundation design, which is an obstruction for mass customization/production and industrialization in relation to certifying authorities. This paper presents the outcome of on-going research and development program that provides solution...

  15. A Preliminary Study on Bucket Foundations under Transient Lateral Loading

    DEFF Research Database (Denmark)

    Foglia, Aligi; Ibsen, Lars Bo; Nielsen, Søren Kjær

    2013-01-01

    This study aims at investigating the behaviour of monopod bucket foundations through a physical model. The foundation is installed in dense water-saturated sand and is subjected to lateral load applied at different rates. The different loading rates allow for exploring the patterns of response...... of bucket foundations in different drainage conditions. Particular focus is given to the rapid loading response of the foundation (simulating a 50 year wave or emergency stop of a wind turbine). Important knowledge on the pore pressure development within and around the foundation during loading is achieved....

  16. Wheeled hopping robot

    Science.gov (United States)

    Fischer, Gary J [Albuquerque, NM

    2010-08-17

    The present invention provides robotic vehicles having wheeled and hopping mobilities that are capable of traversing (e.g. by hopping over) obstacles that are large in size relative to the robot and, are capable of operation in unpredictable terrain over long range. The present invention further provides combustion powered linear actuators, which can include latching mechanisms to facilitate pressurized fueling of the actuators, as can be used to provide wheeled vehicles with a hopping mobility.

  17. Integer Valued Autoregressive Models for Tipping Bucket Rainfall Measurements

    DEFF Research Database (Denmark)

    Thyregod, Peter; Carstensen, Niels Jacob; Madsen, Henrik

    1999-01-01

    A new method for modelling the dynamics of rain sampled by a tipping bucket rain gauge is proposed. The considered models belong to the class of integer valued autoregressive processes. The models take the autocorelation and discrete nature of the data into account. A first order, a second order...

  18. Laboratory experiments of bucket foundations under cyclic loading

    DEFF Research Database (Denmark)

    Foglia, Aligi; Ibsen, Lars Bo

    This report collects information on the experimental campaign concerning bucket foundations under lateral cyclic loading conducted by the authors between 2011 and 2014. The report includes a step by step manual on the test procedures and a number of information and graphs for each experiment...

  19. Small-scale Testing of Bucket Foundations in Sand

    DEFF Research Database (Denmark)

    Knudsen, Bjørn S.; Østergaard, Martin Underlin; Ibsen, Lars Bo

    For offshore foundation structures, the loads are of varying nature both in magnitude and duration. For the bucket foundation the dissipation of the pore pressure is highly relevant since it greatly affects the strength of the structure. The build up of pore pressures with varying loading rate is...

  20. Transient Monotonic and Cyclic Load Effects on Mono Bucket Foundations

    DEFF Research Database (Denmark)

    Nielsen, Søren Dam

    and when hitting the foundation they induce high impact loads with a short duration. It is important that the foundation is able to resists these huge loads. Fortunately, the conducted research showed that the capacity of the mono bucket foundation is high to impact loads. When exposed to a huge wave load...

  1. Cost-Effective Mass Production of Mono Bucket Foundations

    DEFF Research Database (Denmark)

    Gres, Szymon; Nielsen, Søren Andreas; Fejerskov, Morten

    2015-01-01

    No recognized procedures exist for the Mono Bucket Foundation design, which is an obstruction for mass customization/production and industrialization in relation to certifying authorities. This paper presents the outcome of on-going research and development program that provides solution...

  2. Numerical analysis of the bucket surface roughness effects in Pelton turbine

    Science.gov (United States)

    Xiao, Y. X.; Zeng, C. J.; Zhang, J.; Yan, Z. G.; Wang, Z. W.

    2013-12-01

    The internal flow of a Pelton turbine is quite complex. It is difficult to analyse the unsteady free water sheet flow in the rotating bucket owing to the lack of a sound theory. Affected by manufacturing technique and silt abrasion during the operation, the bucket surface roughness of Pelton turbine may be too great, and thereby influence unit performance. To investigate the effect of bucket roughness on Pelton turbine performance, this paper presents the numerical simulation of the interaction between the jet and the bucket in a Pelton turbine. The unsteady three-dimensional numerical simulations were performed with CFX code by using the SST turbulence model coupling the two-phase flow volume of fluid method. Different magnitude orders of bucket surface roughness were analysed and compared. Unsteady numerical results of the free water sheet flow patterns on bucket surface, torque and unit performance for each bucket surface roughness were generated. The total pressure distribution on bucket surface is used to show the free water sheet flow pattern on bucket surface. By comparing the variation of water sheet flow patterns on bucket surface with different roughness, this paper qualitatively analyses how the bucket surface roughness magnitude influences the impeding effect on free water sheet flow. Comparison of the torque variation of different bucket surface roughness highlighted the effect of the bucket surface roughness on the Pelton turbine output capacity. To further investigate the effect of bucket surface roughness on Pelton turbine performance, the relation between the relative efficiency loss rate and bucket surface roughness magnitude is quantitatively analysed. The result can be used to predict and evaluate the Pelton turbine performance.

  3. Reliability and Assessment Techniques on Ground Excavation

    Directory of Open Access Journals (Sweden)

    Sanga Tangchawal

    2009-05-01

    Full Text Available Planning and assessment on the excavation of the brittle materials (soil or rock can be done by using the machinery and/or explosives. The reliability assessment has been proposed to predict the failure of ground during excavation process. The stability planning on cutting soil (rock face by machinery can be compared between the deterministic and the statistical method. The risk of using explosives for rock excavation has to concern on the damage and environmental impacts after blasting events.

  4. Effect of Embedment on the Vertical Bearing Capacity of Bucket Foundations in Clay

    DEFF Research Database (Denmark)

    Barari, Amin; Ibsen, Lars Bo

    2011-01-01

    To evaluate the undrained behaviour of bucket foundations installed on Yoldia clay, 100 tests on bucket foundations subject to vertical and moment loadings were conducted at Aalborg university geotechnical centre. Bucket foundations are tubular steel foundations that are installed by sealing...... the top and applying suction inside the bucket. The hydrostatic pressure difference and the deadweight cause the bucket to penetrate the soil. In the present study, results of an experimental study addressing the effect of embedment (skirt length to the diameter) on the undrained bearing capacity...

  5. Slope excavation quality assessment and excavated volume calculation in hydraulic projects based on laser scanning technology

    Directory of Open Access Journals (Sweden)

    Chao Hu

    2015-04-01

    Full Text Available Slope excavation is one of the most crucial steps in the construction of a hydraulic project. Excavation project quality assessment and excavated volume calculation are critical in construction management. The positioning of excavation projects using traditional instruments is inefficient and may cause error. To improve the efficiency and precision of calculation and assessment, three-dimensional laser scanning technology was used for slope excavation quality assessment. An efficient data acquisition, processing, and management workflow was presented in this study. Based on the quality control indices, including the average gradient, slope toe elevation, and overbreak and underbreak, cross-sectional quality assessment and holistic quality assessment methods were proposed to assess the slope excavation quality with laser-scanned data. An algorithm was also presented to calculate the excavated volume with laser-scanned data. A field application and a laboratory experiment were carried out to verify the feasibility of these methods for excavation quality assessment and excavated volume calculation. The results show that the quality assessment indices can be obtained rapidly and accurately with design parameters and scanned data, and the results of holistic quality assessment are consistent with those of cross-sectional quality assessment. In addition, the time consumption in excavation project quality assessment with the laser scanning technology can be reduced by 70%−90%, as compared with the traditional method. The excavated volume calculated with the scanned data only slightly differs from measured data, demonstrating the applicability of the excavated volume calculation method presented in this study.

  6. Slope excavation quality assessment and excavated volume calculation in hydraulic projects based on laser scanning technology

    Directory of Open Access Journals (Sweden)

    Chao Hu

    2015-04-01

    Full Text Available Slope excavation is one of the most crucial steps in the construction of a hydraulic project. Excavation project quality assessment and excavated volume calculation are critical in construction management. The positioning of excavation projects using traditional instruments is inefficient and may cause error. To improve the efficiency and precision of calculation and assessment, three-dimensional laser scanning technology was used for slope excavation quality assessment. An efficient data acquisition, processing, and management workflow was presented in this study. Based on the quality control indices, including the average gradient, slope toe elevation, and overbreak and underbreak, cross-sectional quality assessment and holistic quality assessment methods were proposed to assess the slope excavation quality with laser-scanned data. An algorithm was also presented to calculate the excavated volume with laser-scanned data. A field application and a laboratory experiment were carried out to verify the feasibility of these methods for excavation quality assessment and excavated volume calculation. The results show that the quality assessment indices can be obtained rapidly and accurately with design parameters and scanned data, and the results of holistic quality assessment are consistent with those of cross-sectional quality assessment. In addition, the time consumption in excavation quality assessment with the laser scanning technology can be reduced by 70%–90%, as compared with the traditional method. The excavated volume calculated with the scanned data only slightly differs from measured data, demonstrating the applicability of the excavated volume calculation method presented in this study.

  7. Evolution of Multidirectional Wheels Researches

    Directory of Open Access Journals (Sweden)

    Vasile Cojocaru

    2006-10-01

    Full Text Available The problem of the insufficient space for the internal transport in industrial halls have generated new constructive solutions of wheels, able to facilitate the movement of vehicle in any direction without a rotation of chassis. The main types of multidirectional wheels are presented in this paper (Grabowiecki patent, Mecanum wheel, Kilough platform, Blumrich wheel. In the final part of the paper a graphical analyses of the economized space by omnidirectional vehicles is presented. The paper represents a bibliographical study.

  8. 49 CFR 570.63 - Wheel assemblies.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 6 2010-10-01 2010-10-01 false Wheel assemblies. 570.63 Section 570.63... 10,000 Pounds § 570.63 Wheel assemblies. (a) Wheel integrity. A tire rim, wheel disc or spider shall...) Inspection procedure. Examine visually for the conditions indicated. (b) Cast wheels. Cast wheels shall not...

  9. Toxic hazards of underground excavation

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R.; Chitnis, V.; Damasian, M.; Lemm, M.; Popplesdorf, N.; Ryan, T.; Saban, C.; Cohen, J.; Smith, C.; Ciminesi, F.

    1982-09-01

    Inadvertent intrusion into natural or man-made toxic or hazardous material deposits as a consequence of activities such as mining, excavation or tunnelling has resulted in numerous deaths and injuries in this country. This study is a preliminary investigation to identify and document instances of such fatal or injurious intrusion. An objective is to provide useful insights and information related to potential hazards due to future intrusion into underground radioactive-waste-disposal facilities. The methodology used in this study includes literature review and correspondence with appropriate government agencies and organizations. Key categories of intrusion hazards are asphyxiation, methane, hydrogen sulfide, silica and asbestos, naturally occurring radionuclides, and various mine or waste dump related hazards.

  10. Excavation costs for lunar materials

    Science.gov (United States)

    Carrier, W. D., III

    1979-01-01

    A lunar strip mining system is presented which is capable of excavating and transporting 3 million metric tons of ore per year to a central processing plant on the moon's surface. The mining system would grow from a single front-end loader in the first year, to a fleet of ten haulers in the 30th year. Lunar personnel requirements would consist of a single individual, whose primary function would be to perform maintenance. All of the mining equipment would either operate automatically or by remote control from earth. The projected cost for the lunar mining system is approximately $12 to $37 per ton of ore over the life of the mine, an important part of the overall economics of exploiting lunar resources.

  11. Stockyard equipment buoyed by commodity prices

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-03-15

    Recent contract signings by heavy plant manufacturers show that the market for stockyard equipment is holding its own, despite continued economic uncertainty worldwide. Development by major manufacturers of stacker/reclaimers and bucket wheel excavators are reported. 1 photo.

  12. Simulation-Based Lunar Telerobotics Design, Acquisition and Training Platform for Virtual Exploration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Phase I proposal will develop a virtual test fixture performing a high caliber 3D dynamic reproduction of an prototype lunar bucket wheel excavator prototype...

  13. Handleiding Mont Ventoux on Wheels

    NARCIS (Netherlands)

    Dr. A.E. Schep-Akkerman; Drs. J.T. van der Vinne

    2017-01-01

    De handleiding Mont Ventoux on Wheels is ontwikkeld door Stichting WIEL en Werkplaats Sociaal Domein. In 2017-2018 wordt (evaluatie)onderzoek gedaan naar praktijkervaringen met de aanpak van Mont Ventoux on Wheels. De kern van Mont Ventoux on Wheels is dat een gemengde groep van deelnemers,

  14. Wheel/rail interface optimisation

    NARCIS (Netherlands)

    Shevtsov, I.Y.

    2008-01-01

    In this thesis, wheel/rail interface optimisation, and particularly the problems of wheel and rail profile design are considered. The research task pursued by this thesis engenders investigation of a range of problems. First, geometric properties of contact between wheel and rail are investigated.

  15. Wheel Diameter and Speedometer Reading

    Science.gov (United States)

    Murray, Clifton

    2010-01-01

    Most introductory physics students have seen vehicles with nonstandard wheel diameters; some may themselves drive "low-rider" cars or "big-wheel" pickup trucks. But how does changing wheel diameter affect speedometer readout for a given speed? Deriving the answer can be followed readily by students who have been introduced to rotation, and it…

  16. Archaeology Excavation Simulation: Correcting the Emphasis

    Science.gov (United States)

    Thistle, Paul C.

    2012-01-01

    Museums offering archaeological programs often attempt to use the "sandbox approach" to simulate archaeological excavation work. However, in light of the definition of simulation, and given the realities of actual professional practice in archaeological excavation, the author argues that the activity of troweling for artifacts in loose sand places…

  17. Excavations of Islamic Jarash, 2002-2005

    DEFF Research Database (Denmark)

    Walmsley, Alan George

    2005-01-01

    A preliminary report on the excavations at Jarash's mosque by the Danish-Jordanian Islamic Jarash Project during four seasons between 2002 and 2005.......A preliminary report on the excavations at Jarash's mosque by the Danish-Jordanian Islamic Jarash Project during four seasons between 2002 and 2005....

  18. Understanding Wheel Dynamics.

    Science.gov (United States)

    Proffitt, Dennis R.; And Others

    1990-01-01

    In 5 experiments, assessments were made of subjects' understandings of the dynamics of wheels. The subjects--111 undergraduates and 19 high school physics teachers--made highly erroneous dynamical judgments about this commonplace event, both in explicit problem-solving contexts and when viewing ongoing events. Findings are related to accounts of…

  19. Rotating Wheel Wake

    Science.gov (United States)

    Lombard, Jean-Eloi; Xu, Hui; Moxey, Dave; Sherwin, Spencer

    2016-11-01

    For open wheel race-cars, such as Formula One, or IndyCar, the wheels are responsible for 40 % of the total drag. For road cars, drag associated to the wheels and under-carriage can represent 20 - 60 % of total drag at highway cruise speeds. Experimental observations have reported two, three or more pairs of counter rotating vortices, the relative strength of which still remains an open question. The near wake of an unsteady rotating wheel. The numerical investigation by means of direct numerical simulation at ReD =400-1000 is presented here to further the understanding of bifurcations the flow undergoes as the Reynolds number is increased. Direct numerical simulation is performed using Nektar++, the results of which are compared to those of Pirozzoli et al. (2012). Both proper orthogonal decomposition and dynamic mode decomposition, as well as spectral analysis are leveraged to gain unprecedented insight into the bifurcations and subsequent topological differences of the wake as the Reynolds number is increased.

  20. Color Wheel Windows

    Science.gov (United States)

    Leonard, Stephanie

    2012-01-01

    In this article, the author describes a painting and drawing lesson which was inspired by the beautiful circular windows found in cathedrals and churches (also known as "rose windows"). This two-week lesson would reinforce both the concept of symmetry and students' understanding of the color wheel. (Contains 1 online resource.)

  1. 3-D Color Wheels

    Science.gov (United States)

    DuBois, Ann

    2010-01-01

    The blending of information from an academic class with projects from art class can do nothing but strengthen the learning power of the student. Creating three-dimensional color wheels provides the perfect opportunity to combine basic geometry knowledge with color theory. In this article, the author describes how her seventh-grade painting…

  2. First-stage high pressure turbine bucket airfoil

    Science.gov (United States)

    Brown, Theresa A.; Ahmadi, Majid; Clemens, Eugene; Perry, II, Jacob C.; Holiday, Allyn K.; Delehanty, Richard A.; Jacala, Ariel Caesar

    2004-05-25

    The first-stage buckets have airfoil profiles substantially in accordance with Cartesian coordinate values of X, Y and Z set forth in Table I wherein Z is a perpendicular distance from a plane normal to a radius of the turbine centerline and containing the X and Y values with the Z value commencing at zero in the X, Y plane at the radially innermost aerodynamic section of the airfoil and X and Y are coordinates defining the airfoil profile at each distance Z. The X, Y and Z values may be scaled as a function of the same constant or number to provide a scaled-up or scaled-down airfoil section for the bucket.

  3. Physical Modelling of Bucket Foundations Subjected to Axial Loading

    DEFF Research Database (Denmark)

    Vaitkunaite, Evelina

    Compared to oil and gas structures, marine renewable energy devices are usually much lighter, operate in shallower waters and are subjected to severe cyclic loading and dynamic excitations. These factors result in different structural behaviours. Bucket foundations are a potentially cost-effectiv......Compared to oil and gas structures, marine renewable energy devices are usually much lighter, operate in shallower waters and are subjected to severe cyclic loading and dynamic excitations. These factors result in different structural behaviours. Bucket foundations are a potentially cost......-effective solution for various offshore structures, and not least marine renewables. The present thesis focuses on several critical design problems related to the behaviour of bucket foundations exposed to tensile loading. Among those are the soil-structure interface parameters, tensile loading under various...... displacement rates and tensile cyclic loading. A new laboratory testing facility is constructed allowing large scale foundation model testing under long-term cyclic loadings. Another test set-up - a pressure tank – is employed for the displacement rate analysis. The extensive testing campaign provides valuable...

  4. Fault Analysis and Solution on Bucket Dropping Accident in Hoisting System

    Directory of Open Access Journals (Sweden)

    Chunhui Liu

    2014-01-01

    Full Text Available Overwinding was the main accident in lifting systems of coal mine and bucket dropping accident was the most serious overwinding accident. According to the cause and mechanism of the bucket dropping accident in main shaft hoisting systems, the conclusion that overloading promotion was the main cause of bucket crash accident was obtained with the fault tree analysis method. One theoretical analysis model was established in order to prevent the occurrence of overloaded bucket dropping accident. The model provided scientific basis and steps in theory for qualitative and quantitative analysis on the cause of falling bucket accident and for the study on accident prediction and prevention. This article proposed several feasible technical measures to prevent the bucket crash accident, which had important guiding significance in practical application.

  5. Determination of p-y Curves for Bucket Foundations in Sand Using Finite Element Modeling

    DEFF Research Database (Denmark)

    Knudsen, Bjørn S.; Østergaard, Martin Underlin; Ibsen, Lars Bo

    , the suction bucket has a much smaller ratio between length and diameter, and the suction buckets will thus act more as a rigid object during rotation in the soil. To improve the design of suction buckets through analytical methods, the soil pressure needs to be calculated more precisely since currently...... available p􀀀y curves, linking displacement and soil pressure, are based on more slender cylindrical structures. Using finite element methods, the p􀀀y curves for suction buckets will be determined as a function of the internal angle of friction of the soil, the diameter and the skirt length...... of the suction buckets, which can in turn be applied in determination of soil pressures for analytical design methods of suction bucket foundations....

  6. The ubiquitous photonic wheel

    CERN Document Server

    Aiello, Andrea

    2016-01-01

    A circularly polarized electromagnetic plane wave carries an electric field that rotates clockwise or counterclockwise around the propagation direction of the wave. According to the handedness of this rotation, its \\emph{longitudinal} spin angular momentum density is either parallel or antiparallel to the propagation of light. However, there are also light waves that are not simply plane and carry an electric field that rotates around an axis perpendicular to the propagation direction, thus yielding \\emph{transverse} spin angular momentum density. Electric field configurations of this kind have been suggestively dubbed "photonic wheels". It has been recently shown that photonic wheels are commonplace in optics as they occur in electromagnetic fields confined by waveguides, in strongly focused beams, in plasmonic and evanescent waves. In this work we establish a general theory of electromagnetic waves {propagating along a well defined direction, which carry} transverse spin angular momentum density. We show th...

  7. Hopping Robot with Wheels

    Science.gov (United States)

    Barlow, Edward; Marzwell, Nevellie; Fuller, Sawyer; Fionni, Paolo; Tretton, Andy; Burdick, Joel; Schell, Steve

    2003-01-01

    A small prototype mobile robot is capable of (1) hopping to move rapidly or avoid obstacles and then (2) moving relatively slowly and precisely on the ground by use of wheels in the manner of previously reported exploratory robots of the "rover" type. This robot is a descendant of a more primitive hopping robot described in "Minimally Actuated Hopping Robot" (NPO- 20911), NASA Tech Briefs, Vol. 26, No. 11 (November 2002), page 50. There are many potential applications for robots with hopping and wheeled-locomotion (roving) capabilities in diverse fields of endeavor, including agriculture, search-and-rescue operations, general military operations, removal or safe detonation of land mines, inspection, law enforcement, and scientific exploration on Earth and remote planets. The combination of hopping and roving enables this robot to move rapidly over very rugged terrain, to overcome obstacles several times its height, and then to position itself precisely next to a desired target. Before a long hop, the robot aims itself in the desired hopping azimuth and at a desired takeoff angle above horizontal. The robot approaches the target through a series of hops and short driving operations utilizing the steering wheels for precise positioning.

  8. Numerical simulation of cavitation flow characteristic on Pelton turbine bucket surface

    Science.gov (United States)

    Zeng, C. J.; Xiao, Y. X.; Zhu, W.; Yao, Y. Y.; Wang, Z. W.

    2015-01-01

    The internal flow in the rotating bucket of Pelton turbine is free water sheet flow with moving boundary. The runner operates under atmospheric and the cavitation in the bucket is still a controversial problem. While more and more field practice proved that there exists cavitation in the Pelton turbine bucket and the cavitation erosion may occur at the worst which will damage the bucket. So a well prediction about the cavitation flow on the bucket surface of Pelton turbine and the followed cavitation erosion characteristic can effectively guide the optimization of Pelton runner bucket and the stable operation of unit. This paper will investigate the appropriate numerical model and method for the unsteady 3D water-air-vapour multiphase cavitation flow which may occur on the Pelton bucket surface. The computational domain will include the nozzle pipe flow, semi-free surface jet and runner domain. Via comparing the numerical results of different turbulence, cavity and multiphase models, this paper will determine the suitable numerical model and method for the simulation of cavitation on the Pelton bucket surface. In order to investigate the conditions corresponding to the cavitation phenomena on the bucket surface, this paper will adopt the suitable model to simulate the various operational conditions of different water head and needle travel. Then, the characteristics of cavitation flow the development process of cavitation will be analysed in in great detail.

  9. The quadruple cruciate sign of simultaneous bicompartmental medial and lateral bucket-handle meniscal tears

    Energy Technology Data Exchange (ETDEWEB)

    Bugnone, Alejandro N. [University of Miami School of Medicine/Jackson Memorial Hospital, Department of Radiology, Miami, FL (United States); Ramnath, R.R. [Neuroskeletal Imaging, Merritt Island, FL (United States); Davis, S.B. [Orthopedic Center, Huntsville, Alabama (United States); Sedaros, R. [Space Coast Orthopedics, Merritt Island, FL (United States)

    2005-11-01

    We report the second known case of bicompartmental bucket-handle tears of the medial and lateral menisci and the first documented case of the bucket-handle tears occurring simultaneously following trauma, which occurred after a motorcycle accident. Both bucket-handle fragments were displaced into the intercondylar notch. An anterior cruciate ligament tear was also present. Coronal images demonstrated four structures in the intercondylar notch: the anterior and posterior cruciate ligaments and the medial and lateral bucket-handle meniscal fragments. (orig.)

  10. Set-up and Test Procedure for Suction Installation and Uninstallation of Bucket Foundation

    DEFF Research Database (Denmark)

    Koteras, Aleksandra Katarzyna

    This technical report describes the set-up and the test procedures for installation and uninstallation of medium-scale model of bucket foundation that can be performed in the geotechnical part of laboratory in Aalborg University. The installation of bucket foundation can be tested with the use...... of suction under the bucket lid or by applying additional force through the hydraulic piston, forcing the bucket to penetrate into the soil. Tests for uninstallation are performed also with the use of water pressure, as a reverse process to the suction installation. Both installation and uninstallation tests...

  11. The huge ATLAS cavern now fully excavated

    CERN Multimedia

    2002-01-01

    Excavation of the ATLAS cavern is now complete! At the end of two years' work involving a tremendous technical challenge, the civil engineering contractors have succeeded in digging out one of the biggest experimental caverns in the world. Bravo!

  12. 49 CFR 570.10 - Wheel assemblies.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 6 2010-10-01 2010-10-01 false Wheel assemblies. 570.10 Section 570.10... Pounds or Less § 570.10 Wheel assemblies. (a) Wheel integrity. A tire rim, wheel disc, or spider shall... bead through one full wheel revolution and note runout in excess of one-eighth of an inch. (c) Mounting...

  13. 49 CFR 230.114 - Wheel centers.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Wheel centers. 230.114 Section 230.114... Tenders Wheels and Tires § 230.114 Wheel centers. (a) Filling blocks and shims. Driving and trailing wheel... and the wheel center, not more than two thicknesses of shims may be used, one of which must extend...

  14. An in vitro comparison of fluorescence-aided caries excavation and conventional excavation by microhardness testing.

    Science.gov (United States)

    Lai, Guangyun; Zhu, Laikuan; Xu, Xiaohui; Kunzelmann, Karl-Heinz

    2014-01-01

    The aim of this in vitro study was to compare fluorescence-aided caries excavation with conventional excavation based on the Martens and Vickers hardness of dentin at the cavity floor after caries removal. In total, 20 extracted human teeth with dentin caries were bisected through the lesion center into two halves, which were assigned to either the fluorescence-aided caries excavation group or the conventional excavation group. After the treatment, embedding, mounting, and polishing, a line of indentations from the dental pulp across the sound dentin to the cavity floor was made on each sample. The data were compared with Student's t and Mann-Whitney U tests. The calculated Vickers hardness of the sound dentin was 57 ± 10 kg/mm(2) in the fluorescence-aided caries excavation group and 59 ± 8 kg/mm(2) in the conventional excavation group, which is consistent with the previous studies. The absolute and relative Martens hardness measurements of the cavity floor were 224 ± 93 N/mm(2) and 46 ± 17%, respectively, in the fluorescence-aided caries excavation group and 412 ± 75 N/mm(2) and 81 ± 14%, respectively, in the conventional excavation group. Based on either the Martens or Vickers hardness, both the absolute and relative microhardness measurements of the cavity floor after fluorescence-aided caries excavation were significantly lower than the values obtained by conventional excavation. Fluorescence-aided caries excavation showed the tissue-preserving property and was more conservative than the conventional excavation in this in vitro study.

  15. Focal choroidal excavation complicated by choroidal neovascularization.

    Science.gov (United States)

    Xu, Haifeng; Zeng, Fanxing; Shi, Depeng; Sun, Xiaolei; Chen, Xiuli; Bai, Yao

    2014-01-01

    To evaluate the clinical findings of focal choroidal excavation (FCE) complicated by choroidal neovascularization (CNV). Retrospective, observational case series. Twelve patients (15 eyes) with FCE and CNV. The medical records of the patients were reviewed. Clinical findings including age, sex, refraction, color photography, fundus fluorescein angiography (FFA), indocyanine green angiography (ICGA), and spectral-domain optical coherence tomography (OCT) were analyzed. Fundus fluorescein angiography, ICGA, and OCT findings. The 12 patients included 6 women and 6 men. The mean age was 46.8±13.4 years (range, 26-64 years). One half of the patients were emmetropic, and the others were myopic (-0.5 to -3.0 diopters). All subjects were Chinese. Before CNV development, normal appearance or nonspecific pigment disturbance could be seen around the choroidal excavation. Corresponding to the excavation, window defects were observed by FFA, whereas hypofluorescence was found on ICGA images. Choroidal neovascularization in all eyes was classic as revealed by FFA. The OCT images showed that all eyes had a single choroidal excavation. In 7 of the 15 eyes, the choroidal excavation was located subfoveally, and in the other 8 eyes, it was eccentric. All CNV lesions grew from the bottom or slope of the excavation. Three patients had bilateral involvement. Choroidal neovascularization occurred in both conforming and nonconforming type FCEs, regardless of whether the excavation was shallow or deep, subfoveal or eccentric. All CNV lesions responded well to intravitreal injection of anti-vascular endothelial growth factor (VEGF) agents. After a single injection, CNV regressed in 13 of 15 eyes. Two eyes received an additional injection. Nonconforming FCE changed to the conforming type after successful treatment of CNV. Focal choroidal excavation is not always stable. Choroidal neovascularization commonly can be seen in patients with FCE and responds well to intravitreal anti-VEGF agents

  16. BILATERAL CHOROIDAL EXCAVATION IN JUVENILE LOCALIZED SCLERODERMA.

    Science.gov (United States)

    Franklin, Mackenzie L; Day, Shelley

    2018-01-01

    To describe a case of bilateral choroidal excavation in a patient with juvenile localized scleroderma. Case report. An asymptomatic 12-year-old boy with localized scleroderma presented for examination and was found to have bilateral areas of choroidal excavation temporal to the fovea. Previous reports of ocular complications of localized scleroderma have primarily described adnexal and anterior segment changes. This is the second report of choroidal changes in a patient with localized scleroderma, and the first in a pediatric patient.

  17. Robotic Two-Wheeled Vehicle

    Science.gov (United States)

    Nesnas, Issa A. D. (Inventor); Matthews, Jaret B. (Inventor); Edlund, Jeffrey E. (Inventor); Burdick, Joel (Inventor); Abad-Manterola, Pablo (Inventor)

    2014-01-01

    A robotic two-wheeled vehicle comprising a connection body interposed between the two wheels are described. A drum can be coaxially located in a central region of the connection body and can support a hollow arm projecting radially from the drum. A tether can be inserted in the arm and connected to a second drum. Instruments and sensors can be accommodated in a case housed inside each wheel.

  18. Sacred activity by the Method of Excavation

    Directory of Open Access Journals (Sweden)

    Eliana Anjos Furtado

    2014-04-01

    Full Text Available Excavation is a clinical and teaching methodology created by the first author of this article. It constitutes a way of helping subjects think, make and speak. This process occurs through the xcavation of making, unblinding and/or unveiling elements in search for the understanding of sacred activity. Through xcavation, subjects understand their thoughts, values and the society in which they live in as they excavate their life stories and their relations with making, including their daily, social and work activities. We applied a thoughtful analysis to approach the role of excavation and the concept of sacred activity. Sacred activity is the core activity of every human being, which is not necessarily the activity we perform in our everyday or work life. Sacred activity is that in which subjects are inserted and experience integrally, genuinely and with no masking. Through sacred activities, subjects surrender, not only to the activity itself, but also to the other, to himself and into himself, by quest. Seeking sacred activity is, therefore, a process of questioning, excavating the routine of subjects, watching and understanding the content of this excavation, replacing and adjusting what is being unveiled, and thus making this activity sacred. In this analysis, we concluded that, by the method of excavation, the sacralization of this action should allow subjects to have tender relationships, and thus be cured.

  19. Characteristics of Braced Excavation under Asymmetrical Loads

    Directory of Open Access Journals (Sweden)

    Changjie Xu

    2013-01-01

    Full Text Available Numerous excavation practices have shown that large discrepancies exist between field monitoring data and calculated results when the conventional symmetry-plane method (with half-width is used to design the retaining structure under asymmetrical loads. To examine the characteristics of a retaining structure under asymmetrical loads, we use the finite element method (FEM to simulate the excavation process under four different groups of asymmetrical loads and create an integrated model to tackle this problem. The effects of strut stiffness and wall length are also investigated. The results of numerical analysis clearly imply that the deformation and bending moment of diaphragm walls are distinct on different sides, indicating the need for different rebar arrangements when the excavation is subjected to asymmetrical loads. This study provides a practical approach to designing excavations under asymmetrical loads. We analyze and compare the monitoring and calculation data at different excavation stages and find some general trends. Several guidelines on excavation design under asymmetrical loads are drawn.

  20. A Basic Robotic Excavator (the Glenn Digger): Description, Design, and Initial Operation

    Science.gov (United States)

    Bauman, Steve; Newman, Paul; Izadnegahdar, Alain; Johnson, Kyle; Abel, Phillip

    2016-01-01

    This paper describes the design, commercial part selections, fabrication, assembly, installation, and initial operation of a two degree of freedom robotic excavator. Colloquially referred to as "the NASA Glenn Digger," it was designed specifically to be mounted onto, and to operate with, the then newly developed Centaur 2 robotic mobility base. The excavator, when mounted to Centaur 2, is designed to scoop loose regolith from the terrain, raise its loaded bucket up and dump the load into a hopper of at least a 1-m-height. The hopper represents the input to a machine that would process the raw material, such as to produce oxygen from lunar regolith as would be required for long-term lunar habitation. This equipment debuted at the annual Research and Technology Studies ("Desert RATS", Ref. 1) event held north of Flagstaff, Arizona, in September of 2010, when the Digger was successfully joined to Centaur 2 and the shoveling articulation was demonstrated. During 2011, the hardware was modified for added strength, strain gauges were added to measure loads, and the controls were improved in preparation for the 2011 Desert RATS event, where additional "field operations" experience was gained.

  1. Results of Dynamic Calibration of Tipping-Bucket Rain Gauges

    Science.gov (United States)

    Kvicera, V.; Grabner, M.

    2009-04-01

    Experimental research in the Department of Frequency Engineering in the Czech Metrology Institute (CMI) in Prague, the Czech Republic, is focused on stability of received signal on terrestrial radio and optical paths. Rain can cause serious attenuation of electromagnetic waves in the frequency bands over 10 GHz. Therefore, our experimental research is also focused on our own meteorological measurement in the vicinity of experimental radio and optical paths. The heated tipping-bucket raingauge MR3H manufactured by Meteoservis, the Czech Republic, with the collector area of 500 cm2 and the rain amount per tip of 0.1 mm is used at CMI for the measurement of rainfall intensities. The time of tips is recorded with uncertainty of 0.1 second. The obtained time of tips are stored by PC and recorded on CD-ROM. It is generally known higher rainfall intensities measured by tipping-bucket rain gauges are underestimated. Therefore, after static calibration the tipping-bucket rain gauge was dynamically calibrated by water flowmeters. The Brooks FLOMEGA Flow Meters models 5882 and 3750 were used for the rain gauge calibration in the range from 2.6 mm/h to 530 mm/h. The used method of dynamic calibration of raingauges and our experience obtained will be described. The dependence of the measured rain intensity on the reference rain intensity (calibration curve) will be presented. Both the results obtained and the influence of dynamic calibration on our results concerning attenuation of electromagnetic waves due to rain will be discussed. Ministry of Education, Youth and Sports of the Czech Republic under the Project No. OC09076 supported the described work.

  2. Comparison of Calculation Models for Bucket Foundation in Sand

    DEFF Research Database (Denmark)

    Vaitkunaite, Evelina; Molina, Salvador Devant; Ibsen, Lars Bo

    The possibility of fast and rather precise preliminary offshore foundation design is desirable. The ultimate limit state of bucket foundation is investigated using three different geotechnical calculation tools: [Ibsen 2001] an analytical method, LimitState:GEO and Plaxis 3D. The study has focused...... on resultant bearing capacity of variously embedded foundation in sand. The 2D models, [Ibsen 2001] and LimitState:GEO can be used for the preliminary design because they are fast and result in a rather similar bearing capacity calculation compared with the finite element models of Plaxis 3D. The 2D models...

  3. Modelling the embedded rainfall process using tipping bucket data

    DEFF Research Database (Denmark)

    Thyregod, Peter; Arnbjerg-Nielsen, Karsten; Madsen, Henrik

    1998-01-01

    A new method for modelling the dynamics of rain measurement processes is suggested. The method takes the discrete nature and autocorrelation of measurements from the tipping bucket rain gauge into consideration. The considered model is a state space model with a Poisson marginal distribution....... In the model there is only one parameter, a thinning parameter. The model is tested on 39 rain events. The estimated value for the various rain events is reflecting a subjective classification of rain events into frontal and convective rain. Finally, it is demonstrated how the model can be used for simulation...

  4. Lumped-parameter Model of a Bucket Foundation

    DEFF Research Database (Denmark)

    Andersen, Lars; Ibsen, Lars Bo; Liingaard, Morten

    2009-01-01

    As an alternative to gravity footings or pile foundations, offshore wind turbines at shallow water can be placed on a bucket foundation. The present analysis concerns the development of consistent lumped-parameter models for this type of foundation. The aim is to formulate a computationally......, and the quality of the models are tested in the time and frequency domains. It is found that precise results are achieved by lumped-parameter models with two to four internal degrees of freedom per displacement or rotation of the foundation. Further, coupling between the horizontal sliding and rocking cannot...

  5. Reaction Wheel with Embedded MEMS IMU Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation is to embed a MEMS IMU Sensor Chip into a reaction wheel to measure its spin rate as well as wheel attitude rate. We propose to use a reaction wheel...

  6. Clamshell excavation of a permeable reactive barrier

    Science.gov (United States)

    Molfetta, Antonio Di; Sethi, Rajandrea

    2006-06-01

    Nowadays, permeable reactive barriers (PRB) are one of the most widespread techniques for the remediation of contaminated aquifers. Over the past 10 years, the use of iron-based PRBs has evolved from innovative to accepted standard practice for the treatment of a variety of groundwater contaminants (ITRC in: Permeable reactive barriers: lessons learned/new directions. The Interstate Technology and Regulatory Council, Permeable Reactive Barriers Team 2005). Although, a variety of excavation methods have been developed, backhoe excavators are often used for the construction of PRBs. The aim of this study is to describe the emplacement of a full-scale PRB and the benefits deriving from the use of a crawler crane equipped with a hydraulic grab (also known as clamshell excavator) in the excavation phases. The studied PRB was designed to remediate a chlorinated hydrocarbons plume at an old industrial landfill site, in Avigliana, near the city of Torino, in Italy. The continuous reactive barrier was designed to be 120 m long, 13 m deep, and 0.6 m thick. The installation of the barrier was accomplished using a clamshell for the excavation of the trench and a guar-gum slurry to support the walls. The performance of this technique was outstanding and allowed the installation of the PRB in 7 days. The degree of precision of the excavation was very high because of the intrinsic characteristics of this excavation tool and of the use of a concrete curb to guide the hydraulic grab. Moreover, the adopted technique permitted a saving of bioslurry thus minimizing the amount of biocide required.

  7. Mechanical Design Engineering Enabler Project wheel and wheel drives

    Science.gov (United States)

    Nutt, Richard E.; Couch, Britt K.; Holley, John L., Jr.; Garris, Eric S.; Staut, Paul V.

    1992-01-01

    Our group was assigned the responsibility of designing the wheel and wheel drive system for a proof-of-concept model of the lunar-based ENABLER. ENABLER is a multi-purpose, six wheeled vehicle designed to lift and transport heavy objects associated with the construction of a lunar base. The resulting design was based on the performance criteria of the ENABLER. The drive system was designed to enable the vehicle to achieve a speed of 7 mph on a level surface, climb a 30 percent grade, and surpass a one meter high object and one meter wide crevice. The wheel assemblies were designed to support the entire weight of the vehicle on two wheels. The wheels were designed to serve as the main component of the vehicle's suspension and will provide suitable traction for lunar-type surfaces. The expected performance of the drive system for the ENABLER was influenced by many mechanical factors. The expected top speed on a level sandy surface is 4 mph instead of the desired 7 mph. This is due to a lack of necessary power at the wheels. The lack of power resulted from dimension considerations that allowed only an eight horsepower engine and also from mechanical inefficiencies of the hydraulic system. However, the vehicle will be able to climb a 30 percent grade, surpass a one meter high object and one meter wide crevice. The wheel assemblies will be able to support the entire weight of the vehicle on two wheels. The wheels will also provide adequate suspension for the vehicle and sufficient traction for lunar-type surfaces.

  8. Bucket Game with Applications to Set Multicover and Dynamic Page Migration

    NARCIS (Netherlands)

    M. Bienkowski; J. Byrka (Jaroslaw)

    2005-01-01

    htmlabstractWe present a simple two-person Bucket Game, based on throwing balls into buckets, and we discuss possible players’ strategies. We use these strategies to create an approximation algorithm for a generalization of the well known Set Cover problem, where we need to cover each element by at

  9. Unsteady CFD simulation for bucket design optimization of Pelton turbine runner

    Science.gov (United States)

    KUMASHIRO, Takashi; FUKUHARA, Haruki; TANI, Kiyohito

    2016-11-01

    To investigate flow patterns on the bucket of Pelton turbine runners is one of the important issues to improve the turbine performance. By studying the mechanism of loss generation on the flow around the bucket, it becomes possible to optimize the design of inner and outer bucket shape. For making it into study, computational fluid dynamics (CFD) is quite an effective method. It is normally used to simulate the flow in turbines and to expect the turbine performances in the development for many kind of water turbine including Pelton type. Especially in the bucket development, the numerical investigations are more useful than observations and measurements obtained in the model test to understand the transient flow patterns. In this paper, a numerical study on two different design buckets is introduced. The simplified analysis domain with consideration for reduction of computational load is also introduced. Furthermore the model tests of two buckets are also performed by using the same test equipment. As the results of the model test, a difference of turbine efficiency is clearly confirmed. The trend of calculated efficiencies on both buckets agrees with the experiment. To investigate the causes of that, the difference of unsteady flow patterns between two buckets is discussed based on the results of numerical analysis.

  10. New Medium-Scale Laboratory Testing of Bucket Foundation Capacity in Sand

    DEFF Research Database (Denmark)

    Vaitkunaite, Evelina; Ibsen, Lars Bo; Nielsen, Benjaminn Nordahl

    2014-01-01

    This article presents a new testing rig for axially loaded bucket foundations. The medium-scale physical model gives the ability to examine the influence of axial tensile, compressive as well as cyclic loading on bucket foundations subjected to various levels of overburden stress. The properties...

  11. Crafting the Set of Buckets in a R&D Portfolio

    DEFF Research Database (Denmark)

    Santiago, Leonardo; Soares, Verônica Mariana Oliveira

    2017-01-01

    The fact that R&D portfolio should be aligned with firm’s strategy is self-evident. The strategic buckets method is often posited in the literature as an alternative to ensure the strategic alignment. However, crafting the right set of buckets is not a straightforward task. In this paper, we...

  12. Study of a 3D-Finite Element Calculation of Bucket Foundation

    DEFF Research Database (Denmark)

    André Larsen, Kim; Ibsen, Lars Bo

    2004-01-01

    The bucket foundation is a new type of foundation, which has been developed over the past 3 years and today it is used for a Vestas V90-3.0 MW offshore wind turbine as a prototype. Ibsen et al.(2003). The bucket foundation is believed to have great potential in the future offshore wind parks as t...

  13. Buckling Analysis of Bucket Foundations for Wind Turbines in Deep Water

    DEFF Research Database (Denmark)

    Madsen, Søren; Andersen, Lars; Ibsen, Lars Bo

    2011-01-01

    Using large suction caissons for offshore wind turbines is an upcoming technology also referred to as bucket foundations. The bucket foundation does not require heavy installation equipment, but since it is constructed as a thin steel shell structure, instability, in form of buckling, becomes...

  14. Medium-scale Laboratory Installation of Suction Bucket Foundation in Sand

    DEFF Research Database (Denmark)

    Koteras, Aleksandra Katarzyna; Ibsen, Lars Bo

    in appendix. Main report includes also main findings and comparisons of tests. Similar work on the seepage analysis for installation of bucket foundation has been performed based on numerical results. Tests results obtained in laboratory campaign are compared with numerical findings in order to improve...... the design method for installation of the suction bucket foundation...

  15. Dragline bucket improvement survey. Final report, September 30, 1977-September 29, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Stilwell, T.; Kelly, H.; Rumbarger, J.; Dowling, M.

    1979-01-01

    An operating dragline bucket receives a lot of abuse. It logs about a million dig cycles every two or three years, all the while operating through abrasive overburden on a round-the-clock basis. It is to the credit of designers, operators and maintenance men alike that these buckets perform so well under such adverse conditions. Comments made in this report are for the purpose of focusing on areas in which further improvements can be made, and in no way are intended to reflect adversely on the generally high quality of bucket design, use and repair. From December 1977 to September 1978, investigators visited nine surface coal mines to review first-hand the techniques and problems associated with dragline equipment. The contractor also conducted some basic analyses regarding bucket geometry and force patterns. The report concludes that: dragline bucket and rigging designs, while traditionally satisfactory, could be bettered in some areas; the major maintenance problem associated with buckets and associated rigging is abrasive wear; the repair costs for associated rigging (primarily chains) can run in excess of 50% of the repair costs for buckets; there is no established engineering information available regarding stresses, forces, soil flow and soil resistance in relation to dragline buckets; present computer monitoring and analysis equipment could, with appropriate modifications, be utilized to yield useful engineering information.

  16. Constructing a Celestial Calendar Wheel.

    Science.gov (United States)

    Cousineau, Sarah M.

    1999-01-01

    Explains how to create a paper replica of the Bighorn Medicine Wheel, an ancient timepiece thought to have been constructed by the Lakota Indians around 1700 A.D. The Bighorn Wheel uses four key seasonal stars as well as the solstice sunrise and sunset to mark the passage of time through the summer. (WRM)

  17. The expanded spectrum of focal choroidal excavation.

    Science.gov (United States)

    Margolis, Ron; Mukkamala, Sri Krishna; Jampol, Lee M; Spaide, Richard F; Ober, Michael D; Sorenson, John A; Gentile, Ronald C; Miller, Joel A; Sherman, Jerome; Freund, K Bailey

    2011-10-01

    To describe the clinical and imaging findings in patients with focal choroidal excavation. Retrospective observational case series. The medical records of 12 patients (13 eyes) with focal choroidal excavation were reviewed. Clinical histories and imaging findings (including color photography, fundus autofluorescence imaging, fluorescein angiography, indocyanine green angiography, spectral-domain optical coherence tomography, and enhanced depth imaging spectral-domain optical coherence tomography) were analyzed. The mean age of the patients was 45 years (range, 22-62 years). Four patients were Asian. Mean visual acuity was 20/31 (range, 20/20 to 20/100). Mean refractive error was -3.54 diopters (D) (range, 6.00 to -8.00 D). One patient had bilateral involvement. All patients manifested varying degrees of foveal pigmentary changes that were usually hypoautofluorescent on fundus autofluorescence images. Fluorescein angiographic findings varied with degree of retinal pigment epithelial alterations. Indocyanine green angiography revealed relative hypofluorescence. In 7 eyes, spectral-domain optical coherence tomography revealed outer retinal layers conforming to retinal pigment epithelial alterations within the excavation. In the other 6 eyes, spectral-domain optical coherence tomography revealed a separation between the outer retina and the retinal pigment epithelium within the excavation. In 7 eyes studied with enhanced depth imaging spectral-domain optical coherence tomography, there was no evidence of scleral ectasia. Mean choroidal thickness of the uninvolved choroid was thicker than normal at 319 μm (range, 244-439 μm). All lesions remained stable except for in 1 eye, which had findings of central serous chorioretinopathy and secondary type 2 (subretinal) neovascularization. Focal choroidal excavation is a newly described idiopathic entity in eyes having 1 or more focal areas of choroidal excavation. In some patients, there may be an association with central

  18. Stepwise excavation in a permanent molar

    DEFF Research Database (Denmark)

    Lima, Fernanda Ferruzzi; Pascotto, Renata Corrêa; Benetti, Ana Raquel

    2010-01-01

    The current study presents a 17-year clinical report of stepwise excavation and indirect pulp capping in a lower right first molar, with great dentin destruction and a lack of dentin support of the cusps. At the first appointment, indirect pulp capping with calcium hydroxide and a temporary filling...... with zinc oxide cement were performed to minimize the risk of pulp exposure during excavation. After 45 days, the remaining carious tissue was removed and a restoration with glass-ionomer lining (Vitrebond) and resin composite (P-50) was performed. Satisfactory morphology and function of the restoration...

  19. Natural course of symptomatic focal choroidal excavation.

    Science.gov (United States)

    Pierro, Luisa; Casalino, Giuseppe; Introini, Ugo; Gagliardi, Marco; Sergenti, Jessica; Cascavilla, Maria Lucia; Bandello, Francesco

    2015-01-01

    A 32-year-old man was referred to the authors' department for nonspecified macular dystrophy with persistent metamorphopsia in the right eye diagnosed 10 years before and followed using optical coherence tomography. The patient underwent a comprehensive ocular examination, including multimodal imaging evaluation and electrofunctional testing. The diagnosis was consistent with nonconforming focal choroid excavation. Over 10 years, no complications occurred, visual acuity was stable, and optical coherence tomography showed no progression of the lesion during follow-up. In this case, nonconforming symptomatic focal choroid excavation was a nonprogressive condition with good long-term visual outcome. Copyright 2015, SLACK Incorporated.

  20. Pajarito Plateau archaeological surveys and excavations. II

    Energy Technology Data Exchange (ETDEWEB)

    Steen, C R

    1982-04-01

    Los Alamos National Laboratory continues its archaeological program of data gathering and salvage excavations. Sites recently added to the archaeological survey are described, as well as the results of five excavations. Among the more interesting and important discoveries are (1) the apparently well-established local use of anhydrous lime, and (2) a late pre-Columbian use of earlier house sites and middens for garden plots. Evidence indicated that the local puebloan population was the result of an expansion of upper Rio Grande peoples, not an influx of migrants.

  1. Wheel running in the wild.

    Science.gov (United States)

    Meijer, Johanna H; Robbers, Yuri

    2014-07-07

    The importance of exercise for health and neurogenesis is becoming increasingly clear. Wheel running is often used in the laboratory for triggering enhanced activity levels, despite the common objection that this behaviour is an artefact of captivity and merely signifies neurosis or stereotypy. If wheel running is indeed caused by captive housing, wild mice are not expected to use a running wheel in nature. This however, to our knowledge, has never been tested. Here, we show that when running wheels are placed in nature, they are frequently used by wild mice, also when no extrinsic reward is provided. Bout lengths of running wheel behaviour in the wild match those for captive mice. This finding falsifies one criterion for stereotypic behaviour, and suggests that running wheel activity is an elective behaviour. In a time when lifestyle in general and lack of exercise in particular are a major cause of disease in the modern world, research into physical activity is of utmost importance. Our findings may help alleviate the main concern regarding the use of running wheels in research on exercise.

  2. Wheel-type magnetic refrigerator

    Science.gov (United States)

    Barclay, J.A.

    1982-01-20

    The disclosure is directed to a wheel-type magnetic refrigerator capable of cooling over a large temperature range. Ferromagnetic or paramagnetic porous materials are layered circumferentially according to their Curie temperature. The innermost layer has the lowest Curie temperature and the outermost layer has the highest Curie temperature. The wheel is rotated through a magnetic field perpendicular to the axis of the wheel and parallel to its direction of rotation. A fluid is pumped through portions of the layers using inner and outer manifolds to achieve refrigeration of a thermal load.

  3. Carrying BioMath education in a Leaky Bucket.

    Science.gov (United States)

    Powell, James A; Kohler, Brynja R; Haefner, James W; Bodily, Janice

    2012-09-01

    In this paper, we describe a project-based mathematical lab implemented in our Applied Mathematics in Biology course. The Leaky Bucket Lab allows students to parameterize and test Torricelli's law and develop and compare their own alternative models to describe the dynamics of water draining from perforated containers. In the context of this lab students build facility in a variety of applied biomathematical tools and gain confidence in applying these tools in data-driven environments. We survey analytic approaches developed by students to illustrate the creativity this encourages as well as prepare other instructors to scaffold the student learning experience. Pedagogical results based on classroom videography support the notion that the Biology-Applied Math Instructional Model, the teaching framework encompassing the lab, is effective in encouraging and maintaining high-level cognition among students. Research-based pedagogical approaches that support the lab are discussed.

  4. BONE CHAR BASED BUCKET DEFLUORIDATOR IN TANZANIAN HOUSEHOLDS

    DEFF Research Database (Denmark)

    Jacobsen, P.; Dahi, Elian

    1997-01-01

    A household defluoridator, made of a 20 L plastic bucket and 10 kg of bone char, is tested and found efficient to remove fluoride at a capacity of 1.1 mg/g. On an average, the defluoridator reduced the original contents of 8.5 mgF/L to 0.37 mgF/L, i.e. 95.6 %, for a period of 2 months, where 32.5 L...... were treated every day. The defluoridator could be manufactured locally in Ngurdoto village, Arusha Region Tanzania for a price of about 10 US $ per unit. The defluoridator is monitored as operated in 10 households. The defluoridator reduced the fluoride concentration from 10.5 mg/L to less than 1 mg....../L for periods between 4 and 13 months. The users expressed their acceptability of the defluoridator and its performance....

  5. Mountain Bike Wheel Endurance Testing and Modeling

    Science.gov (United States)

    2012-01-01

    Published by Elsevier Ltd. Keywords: Mountain biking; wheels; failure testing 1. Introduction Mountain bike ( MTB ) wheels are subject to a wide range of...accumulates over the life of the wheel and leads to part failure. MTB wheels must be designed to withstand many miles of this loading before failure

  6. Dilmun revisited: excavations at Saar, Bahrain

    Directory of Open Access Journals (Sweden)

    Harriet Crawford

    1997-11-01

    Full Text Available About 2000 BC the island of Bahrain was at the centre of a prosperous trading community - the Early Dilmun civilization - that stretched from Mesopotamia to the Indus Valley. Excavations at the site of Saar have, since 1989, recovered much new information about the layout of the settlement and its local economy and social system.

  7. Excavated Documents Dealing with Chinese Astronomy

    Science.gov (United States)

    Guan, Yuzhen

    The materials ancient Chinese scholars used to write on changed from bamboo strips, wooden tablets, and silk in early China to paper in the later dynasties. This chapter will focus on excavated documents dealing with ancient Chinese astronomy and explore some of the ways that scholars have made use of these archaeological resources.

  8. Archaeological Rescue Excavations at the Dejazmach Gebreslassie ...

    African Journals Online (AJOL)

    Archaeological rescue test excavations that were carried out by the Ethiopian Cultural Heritage Project Site Planning and Conservation sub-component at the Gebreslassie Bariya Gabir palace enclosure at the back of The Main Stelae Field in Aksum from the 5th of June to the 15th of July 2005 yielded at least four ...

  9. Heathrow Terminal 5 Excavation Archive (Data Paper

    Directory of Open Access Journals (Sweden)

    Framework Archaeology

    2014-06-01

    Full Text Available Framework Archaeology is a Joint Venture agreement between Oxford Archaeology (OA and Wessex Archaeology (WA to provide archaeological services to BAA (formerly British Airports Authority, now Heathrow Airport Holdings Ltd. Given the potential scale of some of BAA's projects, the joint venture enables Framework Archaeology to draw on the full resources of both OA and WA, including site staff, specialist managers, administrative support, and technical facilities. In 1993, BAA plc and Heathrow Airport Limited submitted a joint planning application to develop an additional passenger terminal complex (Terminal 5, together with the provision of aircraft aprons and taxiways, and include the realignment of rivers and landscaping. The resulting archaeological excavations were undertaken as three main phases of work. Excavations in 1996 by the Museum of London Archaeology Service of approximately 4 ha of sludge stockpile areas (site code POK96. Between 1999-2000 Framework Archaeology excavated approximately 21 ha in the Perry Oaks sludge works and adjacent areas (WPR98. Framework Archaeology also undertook excavations between 2002-2007 as part of the construction of Terminal 5 (PSH02, TEC05 covering a further 50 hectares. Importantly the aim of the Terminal 5 archaeological programme was to move beyond the description and recovery of archaeological remains and to arrive at an understanding of the history of human inhabitation and the practical ways in which people established their presence in the material, social and political conditions of their day.

  10. Capacities and failure modes of suction bucket foundation with internal bulkheads

    Science.gov (United States)

    Xiao, Zhong; Ge, Borui; Wang, Yan

    2017-08-01

    Suction bucket foundations can be divided into four compartments by cruciform internal bulkheads, thereby yielding better capacity in certain conditions than those without internal bulkheads. As yet, no systematic study has been conducted regarding the effects of cruciform internal bulkheads on the capacities of suction bucket foundations. In this study, we established a large number of finite element models of suction bucket foundations with and without cruciform internal bulkheads and of solid embedded circular foundations. We found the uniaxial capacities and failure modes of suction bucket foundations with various depth ratios to remain basically unaffected by internal bulkheads in uniform clays. However, in inhomogeneous clay with high strength heterogeneity, we observed the uniaxial moment and horizontal capacities and corresponding failure modes of suction bucket foundations with a low depth ratio to be obviously affected by internal bulkheads. In this case, the uniaxial moment capacities, in particular, as well as the horizontal capacities of suction bucket foundations with cruciform internal bulkheads become obviously greater than those without internal bulkheads. Under combined loading, we found the failure envelopes of suction bucket foundations with and without cruciform internal bulkheads and of solid circular foundation to also be basically consistent in uniform clays. However, in inhomogeneous clay with high strength heterogeneity, cruciform internal bulkheads can obviously change the shapes of the failure envelopes of bucket foundations with a small depth ratio. We conclude that when the acting vertical load or foundation depth is relatively small, suction bucket foundations with cruciform internal bulkheads can be subjected to larger moment and horizontal loads in soft clays with high strength heterogeneity.

  11. Voluntary Wheel Running in Mice.

    Science.gov (United States)

    Goh, Jorming; Ladiges, Warren

    2015-12-02

    Voluntary wheel running in the mouse is used to assess physical performance and endurance and to model exercise training as a way to enhance health. Wheel running is a voluntary activity in contrast to other experimental exercise models in mice, which rely on aversive stimuli to force active movement. This protocol consists of allowing mice to run freely on the open surface of a slanted, plastic saucer-shaped wheel placed inside a standard mouse cage. Rotations are electronically transmitted to a USB hub so that frequency and rate of running can be captured via a software program for data storage and analysis for variable time periods. Mice are individually housed so that accurate recordings can be made for each animal. Factors such as mouse strain, gender, age, and individual motivation, which affect running activity, must be considered in the design of experiments using voluntary wheel running. Copyright © 2015 John Wiley & Sons, Inc.

  12. Wheels lining up for ATLAS

    CERN Document Server

    2003-01-01

    On 30 October, the mechanics test assembly of the central barrel of the ATLAS tile hadronic calorimeter was completed in building 185. It is the second wheel for the Tilecal completely assembled this year.

  13. The big wheels of ATLAS

    CERN Multimedia

    2006-01-01

    The ATLAS cavern is filling up at an impressive rate. The installation of the first of the big wheels of the muon spectrometer, a thin gap chamber (TGC) wheel, was completed in September. The muon spectrometer will include four big moving wheels at each end, each measuring 25 metres in diameter. Of the eight wheels in total, six will be composed of thin gap chambers for the muon trigger system and the other two will consist of monitored drift tubes (MDTs) to measure the position of the muons (see Bulletin No. 13/2006). The installation of the 688 muon chambers in the barrel is progressing well, with three-quarters of them already installed between the coils of the toroid magnet.

  14. Physical Modelling of Bucket Foundation Under Long-Term Cyclic Lateral Loading

    DEFF Research Database (Denmark)

    Foglia, Aligi; Ibsen, Lars Bo; Andersen, Lars Vabbersgaard

    2012-01-01

    Offshore wind farms are a promising renewable energy source. The monopod bucket foundation has the potential to become a reliable and cost-effective concept for offshore wind turbines. The bucket foundation must be designed by accounting for the cyclic loading which might endanger the turbine...... functioning. In this article a 1g physical model of bucket foundation under horizontal and moment cyclic loading is described. A testing program including four tests was carried out. Every test was conducted for at least 30000 cycles, each with different loading features. The capability of the model...

  15. 49 CFR 215.103 - Defective wheel.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Defective wheel. 215.103 Section 215.103... § 215.103 Defective wheel. A railroad may not place or continue in service a car, if— (a) A wheel flange... tread of the wheel; (b) The height of a wheel flange on the car, from the tread to the top of the flange...

  16. The possibilites of coal seam underground excavation in Republic of Macedonia with high productive excavation methods

    OpenAIRE

    Despodov, Zoran; Doneva, Nikolinka; Mijalkovski, Stojance

    2008-01-01

    The paper presents mining and geology properties of coal deposits in R.Macedonia predetermined for underground exploitation. Also it will be shown the way of coal seams preparation and development for underground excavation with longwall mining methods. Based on mining and geology properties of coal and it’s caloric value it will be observed the possibilities for application on the longwall mining which is among excavation methods with highest production and capacity applied in the contemp...

  17. MicroCT-based comparison between fluorescence-aided caries excavation and conventional excavation.

    Science.gov (United States)

    Lai, Guangyun; Kaisarly, Dalia; Xu, Xiaohui; Kunzelmann, Karl-Heinz

    2014-02-01

    To evaluate and compare the use of micro-computed tomography (microCT) to investigate the mineral concentration of the treated dentin surface after caries removal with fluorescence-aided caries excavation (FACE) and conventional excavation. 20 extracted human teeth with dentin caries were bisected through the lesion center into two halves which were distributed to a FACE and a conventional excavation group. Tungsten-carbide round burs were used for both groups. Each specimen was investigated with microCT after excavation. The obtained images of all the specimens were evaluated using Image J. Based on the grey values, the linear attenuation coefficients were calculated. Four resin-embedded solid hydroxyapatite phantoms with the gradually increased mineral concentration were used to obtain a calibration curve and equation. Finally, the mineral concentration values of the superficial dentin of each specimen after removal and sound dentin were calculated. The data were compared with the Student's t-test. The statistical results showed that the linear attenuation coefficient (LAC) of the treated surface was significantly lower (P excavation group was 2.98 +/- 0.19 cm(-1). The LAC of sound dentin was 3.89 +/- 0.10 cm(-1). By using the calibration equation, the calculated mineral concentration of the superficial dentin after caries removal were 0.68 +/- 0.14 g/cm3 in the FACE group and 1.05 +/- 0.08 g/cm3 in the conventional excavation group. The mineral concentration of sound dentin was 1.44 +/- 0.04 g/cm3. The mineral concentration of the superficial dentin after caries removal in the FACE group was about 47% of that of sound dentin, while the value in the conventional excavation group was approximately 73% of that of sound dentin. Under the conditions of this in vitro study, the results of the microCT evaluation may imply that FACE was more conservative than conventional excavation.

  18. Fluorescence-aided caries excavation (FACE), caries detector, and conventional caries excavation in primary teeth.

    Science.gov (United States)

    Lennon, Aine M; Attin, Thomas; Martens, Sabine; Buchalla, Wolfgang

    2009-01-01

    The purpose of this paper was to compare the ability of fluorescence-aided caries excavation (FACE) to remove infected dentin in primary teeth with that of conventional methods. Sixty-six extracted carious primary teeth were divided according to lesion size into 3 groups of 22 teeth. Caries excavation was carried out with a slow-speed handpiece and round burs for all groups. In the first group, caries was excavated conventionally using visual tactile criteria. In the second group, a caries detector dye was used to detect carious dentin. In the FACE group, cavities were excited with violet light (370-420 nm) and observed through a 530 nm highpass filter. Orange-red fluorescing areas were removed. Undecalcified thin slices were prepared, stained with Giemsa, and examined for presence of infected dentin using light microscopy. Four samples were lost during processing. Histology showed infected dentin in significantly less FACE samples (3 of 22) compared to conventional excavation (9 of 20; P=.03), but not significantly less compared to caries detector (5 of 20; P=.35). Within the limitations of this in vitro study, it can be concluded that fluorescence-aided caries excavation is more effective than conventional excavation in removal of infected primary dentin.

  19. Estimating the Backup Reaction Wheel Orientation Using Reaction Wheel Spin Rates Flight Telemetry from a Spacecraft

    Science.gov (United States)

    Rizvi, Farheen

    2013-01-01

    A report describes a model that estimates the orientation of the backup reaction wheel using the reaction wheel spin rates telemetry from a spacecraft. Attitude control via the reaction wheel assembly (RWA) onboard a spacecraft uses three reaction wheels (one wheel per axis) and a backup to accommodate any wheel degradation throughout the course of the mission. The spacecraft dynamics prediction depends upon the correct knowledge of the reaction wheel orientations. Thus, it is vital to determine the actual orientation of the reaction wheels such that the correct spacecraft dynamics can be predicted. The conservation of angular momentum is used to estimate the orientation of the backup reaction wheel from the prime and backup reaction wheel spin rates data. The method is applied in estimating the orientation of the backup wheel onboard the Cassini spacecraft. The flight telemetry from the March 2011 prime and backup RWA swap activity on Cassini is used to obtain the best estimate for the backup reaction wheel orientation.

  20. 43 CFR 10.3 - Intentional archaeological excavations.

    Science.gov (United States)

    2010-10-01

    ... Cultural Patrimony From Federal or Tribal Lands § 10.3 Intentional archaeological excavations. (a) General... objects, sacred objects, or objects of cultural patrimony that are excavated intentionally from Federal or... excavation of human remains, funerary objects, sacred objects, or objects of cultural patrimony from Federal...

  1. 29 CFR 1926.651 - Specific excavation requirements.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Specific excavation requirements. 1926.651 Section 1926.651..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Excavations § 1926.651 Specific excavation requirements. (a) Surface encumbrances. All surface encumbrances that are located so as...

  2. Numerical and Experimental Investigations of the Flow in a Stationary Pelton Bucket

    Science.gov (United States)

    Nakanishi, Yuji; Fujii, Tsuneaki; Kawaguchi, Sho

    A numerical code based on one of mesh-free particle methods, a Moving-Particle Semi-implicit (MPS) Method has been used for the simulation of free surface flows in a bucket of Pelton turbines so far. In this study, the flow in a stationary bucket is investigated by MPS simulation and experiment to validate the numerical code. The free surface flow dependent on the angular position of the bucket and the corresponding pressure distribution on the bucket computed by the numerical code are compared with that obtained experimentally. The comparison shows that numerical code based on MPS method is useful as a tool to gain an insight into the free surface flows in Pelton turbines.

  3. A Similitude Theory for Bucket Foundations Under Monotonic Horizontal Load in Dense Sand

    DEFF Research Database (Denmark)

    Foglia, Aligi; Ibsen, Lars Bo

    2013-01-01

    of bucket foundations under horizontal load, is put forward. A constitutive law of the soil and a load-displacement relationship for the bucket foundation are theoretically obtained. Triaxial tests of sand, and small-scale tests of bucket foundation, are respectively employed to corroborate the theory....... Attention is given to the different behaviour shown during the compressive and dilative phases of the soil. Some analogy between triaxial tests and tests of bucket foundation are pointed out. A theoretically derived power law is found capable to represent the dimensionless horizontal load......-displacement curves of experimental results. In accordance with the theory, the exponent of the power law slightly varies between tests with considerably different features. The non-dimensional moment-rotation relationship is represented by a power law as well. The approach is considered valid for fatigue design...

  4. Climate Prediction Center (CPC) Global Monthly Leaky Bucket Soil Moisture Analysis

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Monthly global soil moisture, runoff, and evaporation data sets produced by the Leaky Bucket model at 0.5? ? 0.5? resolution for the period from 1948 to the present....

  5. Spontaneous healing of bucket handle tear of the medial meniscus associated with ACL tear

    OpenAIRE

    Rabelo,Neiffer Nunes; Rabelo,Nícollas Nunes; Cunha,Aluísio Augusto Gonçalves; Correia,Francisco

    2013-01-01

    We report a case of injury of the medial bucket handle meniscal tears (BH), which resolved spontaneously, in association with anterior cruciate ligament (ACL) injury. The patient twisted his left knee during a fight in martial arts, progressing to pain and joint locking and a sense of distortion. In NMR it could be seen bucket-handle tear of the medial meniscus with displacement of the fragment to the intercondylar region, rupture of the lateral meniscus and ACL tear. After conservative treat...

  6. Selected aspects of designing deep excavations

    Directory of Open Access Journals (Sweden)

    Obrzud Rafał F.

    2016-09-01

    Full Text Available This paper analyzes two approaches to serviceability limit state (SLS verification for the deep excavation boundary value problem. The verification is carried out by means of the finite element (FE method with the aid of the commercial program ZSoil v2014. In numerical simulations, deep excavation in non-cohesive soil is supported with a diaphragm wall. In the first approach, the diaphragm wall is modeled with the Hookean material assuming reduced average stiffness and possible concrete cracking. The second approach is divided into two stages. In the first stage, the wall is modeled by defining its stiffness with the highest nominal Young’s modulus. The modulus makes it possible to find design bending moments which are used to compute the minimal design cross-section reinforcement for the retaining structure. The computed reinforcement is then used in a non-linear structural analysis which is viewed as the “actual” SLS verification.

  7. Focal choroidal excavation associated with focal retinochoroiditis.

    Science.gov (United States)

    Ohki, Tetsutaro; Sakai, Tsutomu; Tsuneoka, Hiroshi

    2015-01-01

    To describe detailed spectral-domain optical coherence tomography (OCT) findings for two patients with focal choroidal excavation (FCE) associated with focal retinochoroiditis. Three eyes from two patients with FCE associated with focal retinochoroiditis were evaluated by funduscopy, fluorescence angiography, indocyanine green angiography, and spectral-domain OCT during follow-up. Both patients with focal retinochoroiditis developed new FCE after oral steroid treatment and two eyes showed regression of the FCE during the follow-up. Both eyes from one patient transformed from the conforming to the nonconforming type and neither of the eyes were stable during the follow-up. Ultimately, all eyes exhibited the conforming-type FCE. Focal choroidal excavation can be seen as a tomographic phenotype after the treatment of focal retinochoroiditis. Spectral-domain OCT was useful for detecting the development of FCE after the treatment and for observing FCE regression.

  8. Excavating and loading equipment for peat mining

    Science.gov (United States)

    Mikhailov, A. V.; Zhigulskaya, A. I.; Yakonovskaya, T. B.

    2017-10-01

    Recently, the issues of sustainable development of Russian regions, related to ensuring energy security, are more urgent than ever. To achieve sustainable development, an integrated approach to the use of local natural resources is needed. Practically in all north regions of the Russian Federation, peat as a local natural resource is widespread, which has a practical application in the area of housing services. The paper presents the evaluation of technologies for open-pit peat mining, as well as analysis of technological equipment for peat production. Special attention is paid to a question of peat materials excavating and loading. The problem of equipment selection in a peat surface mine is complex. Many features, restrictions and criteria need to be considered. Use of low and ultra-low ground pressure excavators and low ground pressure front-end loaders with full-range tires to provide the necessary floatation in the peat bog environment is offered.

  9. Choroidal neovascularization associated with focal choroidal excavation.

    Science.gov (United States)

    Lee, Jae Hyung; Lee, Won Ki

    2014-03-01

    To describe the clinical and imaging characteristics of choroidal neovascularization (CNV) accompanied by focal choroidal excavation. Retrospective, interventional case series. The medical records of 16 patients (16 eyes) were reviewed. Imaging findings including fluorescein angiography (FA), indocyanine green angiography, and spectral-domain optical coherence tomography (SD OCT) were analyzed. CNV complexes were primarily located beneath the retinal pigment epithelium (type 1 CNV) in 9 eyes and in the subneurosensory retinal space (type 2 CNV) in 7 eyes, as assessed by SD OCT. Seven of 8 patients over 50 years old had type 1 CNV, and 6 of 8 patients under 50 had type 2 lesions. All 7 eyes with type 2 CNV exhibited classic CNV on FA. Additionally, 7 of 9 eyes with type 1 CNV had the classic pattern, and in these eyes, the CNV complexes were confined to the concavity of choroidal excavation. In 15 patients treated by anti-vascular endothelial growth factor (anti-VEGF) injections, the mean best-corrected visual acuity improved from 20/44 to 20/26 with a mean of 3.7 injections during a mean follow-up period of 14.5 months. The CNV growth pattern and extent seem to be determined by the degree of damage to the retinal pigment epithelium/Bruch membrane complex resulting from choroidal excavation, as well as age. Neovascular complexes tend to be located within the boundary of choroidal excavation and are revealed as classic patterns on FA, even in type 1 CNV. Anti-VEGF was notably effective for treating these lesions, with a low rate of recurrence. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Lunar Regolith Excavation Student Competition Design

    Science.gov (United States)

    Nething, Julia

    2009-01-01

    The Surface Systems team is working to learn about lunar regolith and how we can use it as a source of air, water, and fuel for spacecrafts. However, excavation of this valuable regolith is difficult because the robot has to conform to many specifications (mass limit, efficiency level, etc.). NASA has therefore decided to include college students and companies in the search to create the best robot by making it into a competition.

  11. Forces acting on particles in a Pelton bucket and similarity considerations for erosion

    Science.gov (United States)

    Rai, A. K.; Kumar, A.; Staubli, T.

    2016-11-01

    High sediment transport rates cause severe erosion issues in hydropower plants leading to interruptions in power generation, decrease in efficiency and shutdown for repair and maintenance. For Pelton turbines operating at high head, the issue of erosion is severe, especially in components like buckets, nozzle rings and needles. Goal of the study is to develop erosion focussed guidelines for both designing as well as operating hydropower plants with Pelton runners. In this study, the flow of sediment inside a Pelton bucket with respect to forces acting on solid particles is analysed with an analytical approach by considering different dynamic forces originating from the rotation of the turbine, the curvature of the buckets, and the Coriolis effect. Further, the path of sediment particles and its effect on erosion phenomena are analysed based on the process of separation of different sized sediment particles from streamlines. The data relating to head, power, discharge, number of jet and efficiency of 250 hydropower plants installed all over the world were analysed in this study to find the major factors related to erosion in Pelton turbine bucket. From analysis of different force ratios, it is found that an increase of D/B, i.e. the ratio of pitch circle diameter and bucket width, and/or decrease of specific speed (nq) enhances erosion. As the erosion process depends significantly on nondimensional parameters D/B and nq, these are considered as similarity measures for scaling of the erosion process in the Pelton buckets of various sizes.

  12. Contiguous Pile Wall as a Deep Excavation Supporting System

    Directory of Open Access Journals (Sweden)

    Venkata Ramasubbarao GODAVARTHI

    2012-08-01

    Full Text Available Providing space for parking, public amenities, etc in multi-storey buildings at town centres has created a need to go deep excavations into ground. Deep excavations are supported by systems like conventional retaining walls, sheet pile walls, braced walls, diaphragm walls and pile walls. This article describes various excavation supporting systems that are in vogue essentially contiguous pile wall and its advantages. A detailed design methodology of an excavation supporting system is furnished in this study. A case study on the Contiguous pile wall retaining system for supporting a deep excavation at a town centre is presented.

  13. Telerobotic excavation system for unexploded ordnance retrieval

    Energy Technology Data Exchange (ETDEWEB)

    Burks, B.L.; Killough, S.M.; Thompson, D.H. [Oak Ridge National Lab., TN (United States). Robotics and Process Systems Div.; Rossi, R.A. [Office of the Project Manager for Ammunition Logistics, Picatinny Arsenal, NJ (United States)

    1994-12-31

    The small emplacement excavator (SEE) is a ruggedized military vehicle with backhoe and front loader used by the US Army for unexploded ordnance (UXO) retrieval and general utility excavation activities. In order to evaluate the feasibility of removing personnel from the vehicle during high-risk excavation tasks a development and demonstration project was initiated to evaluate performance capabilities of the SEE under telerobotic control. A technology demonstration of the TSEE was conducted at McKinley Range, Redstone Arsenal, Huntsville, Alabama on 13--17 September, 1993. The primary objective of the demonstration was to evaluate and demonstrate the feasibility of remote UXO retrieval. During the demonstration, explosive ordnance disposal specialists were instructed on telerobotic operation of the TSEE, and then were asked to complete a simulated UXO retrieval task. Participants then submitted an evaluation of the system including human factors performance data. This presentation will describe the TSEE, retrieval demonstration, and summarize results of the performance evaluations. Some examples of the results are given below. Seventy percent of the demonstration participants found the tasks were as easy or easier to accomplish utilizing the remote system than with an unmodified system. Similarly, eighty percent of the participants found the TSEE hand controller was as easy or easier to use than the normal manual controls.

  14. National Advanced Drilling and Excavation Technologies Program

    Energy Technology Data Exchange (ETDEWEB)

    None

    1993-06-15

    The second meeting of Federal agency representatives interested in the National Advanced Drilling and Excavation Technologies (NADET) Program took place on June 15, 1993. The Geothermal Division of the U.S. Department of Energy (DOE) hosted the meeting at the Washington, D.C., offices of DOE. Representatives from the National Science Foundation, U.S. Geological Survey, U.S. Bureau of Mines, National Institute of Standards and Technology, National Aeronautics and Space Administration, Environmental Protection Agency, and various offices within the Department of Energy attended. For a complete list of attendees see Attachment A. The purpose of the meeting was: (1) to cover the status of efforts to gain formal approval for NADET, (2) to brief participants on events since the last meeting, especially two recent workshops that explored research needs in drilling and excavation, (3) to review some recent technological advances, and (4) to solicit statements of the importance of improving drilling and excavation technologies to the missions of the various agencies. The meeting agenda is included as Attachment B.

  15. Bucket Brigades to Increase Productivity in a Luxury Assembly Line

    Directory of Open Access Journals (Sweden)

    Filippo De Carlo

    2013-08-01

    Full Text Available One of the most challenging issues in manual assembly lines is to achieve the best balance of workloads. There are many analytic approaches to solve this problem, but they are often neglected, since they are time-consuming and require high level engineering skills. Fashion bags packaging lines must comply with a number of different products with low production volumes, while the organization of the line is often under the mere responsibility of the foreman, who balances workloads in an empirical way. The aim of this work is to evaluate the effectiveness of the arrangement of bucket brigades (BBs for an assembly line of luxury handbags. To do this, it was decided to perform a testing activity in a company producing fashion handbags in order to compare the self-made design with the BBs and with a simple assembly line balancing problem algorithm. The originality of this research lies in the fact that there are no studies in the literature on BBs applied to the packaging of highly variable small batches. The results were excellent, showing the advantages of BBs in terms of flexibility, the reduction of work in the process and the ability to handle small anomalies.

  16. Excavation of Regolith by Impinging Jets of Gas

    Science.gov (United States)

    Metzger, Philip T.; Immer, Christopher D.; Vu, Bruce T.; Donahue, Carly M.

    2006-01-01

    There are many situations in nature and technology where particulate matter is excavated by a fluid jet. Such a process is often used to excavate soil or to dig wells. Air jets are often used to transport particulate matter such as powders in various industrial processes. Similar situations occur in nature, as when waterfalls scour holes in sand. In other cases, the excavation is unwanted such as when a rocket lands on the sandy or dusty surface of a planet or moon. Recent research into regolith excavation by gas jets has obtained new insights into the physical processes of that excavation, and these may lead to new advances in technology for more efficient fluid-jet excavation processes and for better control of the unwanted excavation effects of landing rockets. This talk will explain the new insights and point to future work supporting lunar exploration.

  17. Focal choroidal excavation in eyes with central serous chorioretinopathy.

    Science.gov (United States)

    Ellabban, Abdallah A; Tsujikawa, Akitaka; Ooto, Sotaro; Yamashiro, Kenji; Oishi, Akio; Nakata, Isao; Miyake, Masahiro; Akagi-Kurashige, Yumiko; Ueda-Arakawa, Naoko; Arichika, Shigeta; Yoshitake, Shin; Takahashi, Ayako; Yoshimura, Nagahisa

    2013-10-01

    To study the prevalence and 3-dimensional (3-D) tomographic features of focal choroidal excavations in eyes with central serous chorioretinopathy (CSC) using swept-source optical coherence tomography (OCT). Prospective, cross-sectional study. We examined 116 consecutive eyes with CSC with a prototype 3-D swept-source OCT. 3-D images of the shape of the macular area, covering 6 × 6 mm(2), were reconstructed by segmentation of the outer surface of the retinal pigment epithelium (RPE). The 3-D swept-source OCT detected focal choroidal excavations in 9 eyes (7.8%). The 3-D scanning protocol, coupled with en face scans, allowed for clear visualization of the excavation morphology. In 5 eyes with focal excavations, unusual choroidal tissue was found beneath the excavation, bridging the bottom of the excavation and the outer choroidal boundary. Additionally, 3 of those 5 eyes showed a suprachoroidal space below the excavation, as if the outer choroidal boundary is pulled inward by this bridging tissue. The focal choroidal excavations were located within fluorescein leakage points and areas of choroidal hyperpermeability. Eyes with focal choroidal excavations were more myopic (-4.42 ± 2.92 diopters) than eyes without excavations (-0.27 ± 1.80 diopters, P = .001). Subfoveal choroidal thickness was significantly thinner (301.3 ± 60.1 μm) in eyes with focal excavations than in eyes without the excavations (376.6 ± 104.8 μm, P = .036). Focal choroidal excavations were present in 7.8% of eyes with CSC. In these eyes, focal choroidal excavations may have formed from RPE retraction caused by focal scarring of choroidal connective tissue. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Two new wheels for ATLAS

    CERN Multimedia

    2002-01-01

    Juergen Zimmer (Max Planck Institute), Roy Langstaff (TRIUMF/Victoria) and Sergej Kakurin (JINR), in front of one of the completed wheels of the ATLAS Hadronic End Cap Calorimeter. A decade of careful preparation and construction by groups in three continents is nearing completion with the assembly of two of the four 4 m diameter wheels required for the ATLAS Hadronic End Cap Calorimeter. The first two wheels have successfully passed all their mechanical and electrical tests, and have been rotated on schedule into the vertical position required in the experiment. 'This is an important milestone in the completion of the ATLAS End Cap Calorimetry' explains Chris Oram, who heads the Hadronic End Cap Calorimeter group. Like most experiments at particle colliders, ATLAS consists of several layers of detectors in the form of a 'barrel' and two 'end caps'. The Hadronic Calorimeter layer, which measures the energies of particles such as protons and pions, uses two techniques. The barrel part (Tile Calorimeter) cons...

  19. Optical wheel-rotation sensor

    Science.gov (United States)

    Veeser, Lynn R.; Rodriguez, Patrick A.; Forman, Peter; Deeter, Merritt N.

    1994-09-01

    We describe a fiber-optic rotation sensor being developed for anti-lock braking systems. The basis of the sensor is the magneto-optic detection of the magnetic fields generated by a wheel of alternating magnetized magnets fixed to a wheel of the automobile. Highly sensitive iron garnet crystals serve as the magneto-optic sensing elements. For films with perpendicularly- magnetized domains, the domain structure produces diffraction which is magnetic-field dependent. Exploitation of this effect permits the construction of magneto-optic magnetic field sensors requiring no polarization elements or lenses.

  20. Chemistry. Inventing the nanomolecular wheel.

    Science.gov (United States)

    Siegel, Jay

    2005-10-07

    The wheel is considered the canonical invention leading to all manner of mechanical devices. Rotating machinery is also being investigated at the nanoscale as researchers attempt to create molecular analogs of wheels and motors. But will these devices be merely imitations of macroscopic machines? In his Perspective, Siegel discusses results reported in the same issue by Fletcher et al. in which a four-stroke chemical nanoengine is reported. By a series of bond-breaking and bond-forming steps, a molecular structure is caused to undergo directed rotation. The development of structures of this kind, which are not merely miniaturized macromachines, may lead to other devices for executing controlled oscillatory motion.

  1. Propulsion Wheel Motor for an Electric Vehicle

    Science.gov (United States)

    Figuered, Joshua M. (Inventor); Herrera, Eduardo (Inventor); Waligora, Thomas M. (Inventor); Bluethmann, William J. (Inventor); Farrell, Logan Christopher (Inventor); Lee, Chunhao J. (Inventor); Vitale, Robert L. (Inventor); Winn, Ross Briant (Inventor); Eggleston, IV, Raymond Edward (Inventor); Guo, Raymond (Inventor); hide

    2016-01-01

    A wheel assembly for an electric vehicle includes a wheel rim that is concentrically disposed about a central axis. A propulsion-braking module is disposed within an interior region of the wheel rim. The propulsion-braking module rotatably supports the wheel rim for rotation about the central axis. The propulsion-braking module includes a liquid cooled electric motor having a rotor rotatable about the central axis, and a stator disposed radially inside the rotor relative to the central axis. A motor-wheel interface hub is fixedly attached to the wheel rim, and is directly attached to the rotor for rotation with the rotor. The motor-wheel interface hub directly transmits torque from the electric motor to the wheel rim at a 1:1 ratio. The propulsion-braking module includes a drum brake system having an electric motor that rotates a cam device, which actuates the brake shoes.

  2. Reaction Wheel Disturbance Model Extraction Software Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Reaction wheel disturbances are some of the largest sources of noise on sensitive telescopes. Such wheel-induced mechanical noises are not well characterized....

  3. Experimental heat and mass transfer of the separated and coupled rotating desiccant wheel and heat wheel

    Energy Technology Data Exchange (ETDEWEB)

    Enteria, Napoleon; Yoshino, Hiroshi; Mochida, Akashi; Takaki, Rie [Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan); Satake, Akira [Technical Research Institute, Maeda Corporation, Tokyo 179-8914 (Japan); Yoshie, Ryuichiro [Faculty of Engineering, Tokyo Polytechnic University, Atsugi 243-0297 (Japan); Mitamura, Tiruaki [Faculty of Engineering, Ashikaga Institute of Technology, Ashikaga 326-8558 (Japan); Baba, Seizo [Earth Clean Tohoku Co., Ltd., Sendai 984-0038 (Japan)

    2010-07-15

    The experimental evaluation of the separated and coupled rotating desiccant wheel and heat wheel is reported. The study aims to investigate the performance of the desiccant wheel and of the heat wheel both when operated separately and jointly. The performance evaluation of the desiccant wheel is based on its moisture removal capacity (MRC), moisture removal regeneration (MRR), and moisture mass balance (MMB). In addition, the study used the total energy balance (TEB), sensible coefficient of performance (COP{sub Sensible}), latent coefficient of performance (COP{sub Latent}) and, total coefficient of performance (COP{sub Total}). The performance of the heat wheel is based on its effectiveness. The COP{sub Sensible}, COP{sub Latent} and, COP{sub Total} are used in the performance evaluation of the coupled desiccant wheel and heat wheel. The general results of the study show that the MRC, MRR and MMB coupled with the TEB, COP{sub Latent}, COP{sub Sensible} and COP{sub Total} predict adequately the performance of the desiccant wheel. In addition, the coupled operation of the desiccant wheel and heat wheel, contributed to the reduction of the external thermal energy requirement for the regeneration of the desiccant wheel. This study can be applied in other researches seeking evaluation of the desiccant wheel, heat wheel, and their combined operation. Moreover, the data presented here are significant for the desiccant wheel benchmarking and for evaluation of the desiccant wheel models. (author)

  4. Some peculiarities of corrosion of wheel steel

    OpenAIRE

    Alexander SHRAMKO; Alfred KOZLOWSKY; Elena BELAJA; Yuriy PROIDAK; Sofia PINCHUK; Svetlana GUBENKO

    2009-01-01

    Corrosion mechanism and rate of different chemical composition and structural condition of wheel steel were investigated. It was shown that “white layers”, variation in grain size and banding of wheel steel structure results in corrosion rate. Microstructure of steel from different elements of railway wheels after operation with corrosion was investigated. Wheel steel with addition of vanadium corroded more quickly than steel without vanadium. Non-metallic inclusions are the centre of corrosi...

  5. Bucket-handle meniscal tears of the knee: sensitivity and specificity of MRI signs

    Energy Technology Data Exchange (ETDEWEB)

    Dorsay, Theodore A.; Helms, Clyde A. [Department of Radiology, Duke University Medical Center, Erwin Road, Room 1504, NC 27710, Durham (United States)

    2003-05-01

    To determine the sensitivity and specificity of reported MRI signs in the evaluation of bucket-handle tears of the knee.Design and patients A retrospective analysis of 71 knee MR examinations that were read as displaying evidence of a bucket-handle or ''bucket-handle type'' tear was performed. We evaluated for the presence or absence of the absent bow tie sign, the coronal truncation sign, the double posterior cruciate ligament (PCL) sign, the anterior flipped fragment sign, and a fragment displaced into the intercondylar notch. Sensitivity and specificity were calculated relative to the gold standard of arthroscopy. Forty-three of 71 cases were surgically proven as bucket-handle tears. The absent bow tie sign demonstrated a sensitivity of 88.4%. The presence of at least one of the displaced fragment signs had a sensitivity of 90.7%. A finding of both the absent bow tie sign and one of the displaced fragment signs demonstrated a specificity of 85.7%. The double PCL sign demonstrated a specificity of 100%. The anterior flipped meniscus sign had a specificity of 89.7%. Bucket-handle tears of the menisci, reported in about 10% of most large series, have been described by several signs with MRI. This report gives the sensitivity and specificity of MRI for bucket-handle tears using each of these signs independently and in combination. MRI is shown to be very accurate for diagnosing bucket-handle tears when two or more of these signs coexist. (orig.)

  6. 49 CFR 230.113 - Wheels and tire defects.

    Science.gov (United States)

    2010-10-01

    .... Except as provided in § 230.114, welding on wheels and tires is prohibited. A wheel that has been welded is a welded wheel for the life of the wheel. (a) Cracks or breaks. Wheels and tires may not have a crack or break in the flange, tread, rim, plate, hub or brackets. (b) Flat spots. Wheels and tires may...

  7. Roughness on Dutch railway wheels and rails

    NARCIS (Netherlands)

    Dings, P.C.; Dittrich, M.G.

    1996-01-01

    Surface roughness on 150 railway wheels and on the rails of 30 sites in the Netherlands have been measured. Block braked wheels were found to show higher roughnesses than the rail at any site. The smoothest rail is 8 dB smoother than the smoothest wheel. It was concluded that in reducing railway

  8. 49 CFR 229.73 - Wheel sets.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Wheel sets. 229.73 Section 229.73 Transportation... TRANSPORTATION RAILROAD LOCOMOTIVE SAFETY STANDARDS Safety Requirements Suspension System § 229.73 Wheel sets. (a) The variation in the circumference of wheels on the same axle may not exceed 1/4 inch (two tape sizes...

  9. 16 CFR 1507.8 - Wheel devices.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Wheel devices. 1507.8 Section 1507.8... FIREWORKS DEVICES § 1507.8 Wheel devices. Drivers in fireworks devices commonly known as “wheels” shall be... operation. Wheel devices intended to operate in a fixed location shall be designed in such a manner that the...

  10. PERFORMANCE (ASSESSMENT) OF TWO- WHEEL TRACTORS ...

    African Journals Online (AJOL)

    CHIKA

    within the cash or credit reach of a “small farmer.” For the purpose of this paper, two- wheel tractors are classified as small tractors. Two-wheel tractors are sometimes called by other names such as: single axle tractor, hand- tractor, walking tractor, walk. - behind tractor, etc.[2] The two-wheel tractor with different attachments.

  11. Airborne asbestos fibres monitoring in tunnel excavation.

    Science.gov (United States)

    Gaggero, Laura; Sanguineti, Elisa; Yus González, Adrián; Militello, Gaia Maria; Scuderi, Alberto; Parisi, Giovanni

    2017-07-01

    Tunnelling across ophiolitic formation with Naturally Occurring Asbestos (NOA) can release fibres into the environment, exposing workers, and the population, if fibres spread outside the tunnel, leading to increased risk of developing asbestos-related disease. Therefore, a careful plan of environmental monitoring is carried out during Terzo Valico tunnel excavation. In the present study, data of 1571 samples of airborne dust, collected between 2014 and 2016 inside the tunnels, and analyzed by SEM-EDS for quantification of workers exposure, are discussed. In particular, the engineering and monitoring management of 100 m tunnelling excavation across a serpentinite lens (Cravasco adit), intercalated within calcschists, is reported. At this chrysotile occurrence, 84% of 128 analyzed samples (from the zone closer to the front rock) were above 2 ff/l. However, thanks to safety measures implemented and tunnel compartmentation in zones, the asbestos fibre concentration did not exceed the Italian standard of occupational exposure (100 ff/l) and 100% of samples collected in the outdoor square were below 1 ff/l. During excavation under normal working conditions, asbestos concentrations were below 2 ff/l in 97.4% of the 668 analyzed samples. Our results showed that air monitoring can objectively confirm the presence of asbestos minerals at a rock front in relative short time and provide information about the nature of the lithology at the front. The present dataset, the engineering measures described and the operative conclusions are liable to support the improvement of legislation on workers exposure to asbestos referred to the tunnelling sector, lacking at present. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Focal choroidal excavation: Clinical findings and complications.

    Science.gov (United States)

    Castro Navarro, V; Montero Hernández, J; Navarro Palop, C; Palomares Fort, P; Cervera Taulet, E

    2016-01-01

    To describe the clinical findings and its complications in 2 patients with focal choroidal excavation (FCE). A retrospective case-series including 4 eyes of 2 patients with FCE that underwent a comprehensive ophthalmological examination including slit-lamp examination, colour fundus photography, spectral-domain optical coherence tomography (SD-OCT), fluorescein angiography (FA), and indocyanine green angiography. In the 2 patients, both the anterior and posterior segment evaluations were mostly normal despite the of presence yellowish spots in the macular area of the right eye of patient 1, and of a small yellowish elevated lesion with serous macular detachment in the macular area of the left eye in patient 2. At diagnosis, SD-OCT revealed a conforming FCE in patient 1, and in patient 2, an FCE with perilesional subretinal fluid and a neuroepithelium detachment, suspicious of FCE complicated with central serous retinopathy (CSCR). At one year of follow-up, patient 1 developed choroidal neovascularisation (CNV) over the focal choroidal excavation. FA and indocyanine green angiography examinations revealed areas with hypofluorescence in earlier frames, and a diffuse leakage in late frames. After ranibizumab injections, the SD-OCT of patient 1 revealed no active exudation, while patient 2 showed partial resolution of subretinal fluid. FCE is a newly described entity of unclear aetiology. It is characterised by a choroidal excavation in eyes, with absence of posterior staphyloma, scleral ectasia, trauma, or retinal disease. Although most lesions remain stable, there could be an association with CRSC or CNV. Copyright © 2015 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

  13. Note: Planetary gravities made simple: Sample test of a Mars rover wheel

    Science.gov (United States)

    Viera-López, G.; Serrano-Muñoz, A.; Amigó-Vega, J.; Cruzata, O.; Altshuler, E.

    2017-08-01

    We introduce an instrument for a wide spectrum of experiments on gravities other than our planet's. It is based on a large Atwood machine where one of the loads is a bucket equipped with a single board computer and different sensors. The computer is able to detect the falling (or rising) and then the stabilization of the effective gravity and to trigger actuators depending on the experiment. Gravities within the range 0.4 g-1.2 g are easily achieved with acceleration noise of the order of 0.01 g. Under Martian gravity, we are able to perform experiments of approximately 1.5 s duration. The system includes features such as WiFi and a web interface with tools for the setup, monitoring, and data analysis of the experiment. We briefly show a case study in testing the performance of a model Mars rover wheel in low gravities.

  14. Getting Off the Hamster Wheel

    Science.gov (United States)

    Sammon, Grace

    2005-01-01

    Even with all the external elements of school reform in place, educators can end up spinning their wheels. To make progress, schools must identify the nonnegotiable key elements of their reform plans and use the habits of highly effective schools to turn them into school practice. These habits are: (1) demonstrate high expectations and a vision…

  15. Friction in wheel - rail contacts

    NARCIS (Netherlands)

    Popovici, R.I.

    2010-01-01

    In the autumn, railroad traffic is often interrupted due to the occurrence of slippery tracks. The Dutch main operator (NS) and the infrastructure manager (ProRail) struggle with repeated delays. The layer between wheel and rail causing this phenomenon has not yet been identified, but can be

  16. Computational analysis of Pelton bucket tip erosion using digital image processing

    Science.gov (United States)

    Shrestha, Bim Prasad; Gautam, Bijaya; Bajracharya, Tri Ratna

    2008-03-01

    Erosion of hydro turbine components through sand laden river is one of the biggest problems in Himalayas. Even with sediment trapping systems, complete removal of fine sediment from water is impossible and uneconomical; hence most of the turbine components in Himalayan Rivers are exposed to sand laden water and subject to erode. Pelton bucket which are being wildly used in different hydropower generation plant undergoes erosion on the continuous presence of sand particles in water. The subsequent erosion causes increase in splitter thickness, which is supposed to be theoretically zero. This increase in splitter thickness gives rise to back hitting of water followed by decrease in turbine efficiency. This paper describes the process of measurement of sharp edges like bucket tip using digital image processing. Image of each bucket is captured and allowed to run for 72 hours; sand concentration in water hitting the bucket is closely controlled and monitored. Later, the image of the test bucket is taken in the same condition. The process is repeated for 10 times. In this paper digital image processing which encompasses processes that performs image enhancement in both spatial and frequency domain. In addition, the processes that extract attributes from images, up to and including the measurement of splitter's tip. Processing of image has been done in MATLAB 6.5 platform. The result shows that quantitative measurement of edge erosion of sharp edges could accurately be detected and the erosion profile could be generated using image processing technique.

  17. Seepage Study for Suction Installation of Bucket Foundation in Different Soil Combinations

    DEFF Research Database (Denmark)

    Koteras, Aleksandra Katarzyna; Ibsen, Lars Bo; Clausen, Johan Christian

    2016-01-01

    Research has proven the bucket foundation to be a feasible and an attractive solution for offshore wind turbines. Its potential derives partly from the cost-effectiveness due to the suction-assisted installation. The suction applied under the bucket lid produces a downward driving force and addit......Research has proven the bucket foundation to be a feasible and an attractive solution for offshore wind turbines. Its potential derives partly from the cost-effectiveness due to the suction-assisted installation. The suction applied under the bucket lid produces a downward driving force...... and additionally reduces the soil penetration resistance. This installation process is the most effective in soil with high coefficient of permeability where the flow of pore water is easily induced. However, the technology is still under development and some issues require further investigation and reliable...... around the bucket skirt. The exceedance of critical suction might lead to installation failure due to formation of piping channels, which break the hydraulic seal between the skirt and soil. The excess pore pressure arising due to applied suction changes the effective stress, hence the penetration...

  18. Some peculiarities of corrosion of wheel steel

    Directory of Open Access Journals (Sweden)

    Alexander SHRAMKO

    2009-01-01

    Full Text Available Corrosion mechanism and rate of different chemical composition and structural condition of wheel steel were investigated. It was shown that “white layers”, variation in grain size and banding of wheel steel structure results in corrosion rate. Microstructure of steel from different elements of railway wheels after operation with corrosion was investigated. Wheel steel with addition of vanadium corroded more quickly than steel without vanadium. Non-metallic inclusions are the centre of corrosion nucleation and their influence on corrosion depends on type of inclusion. Mechanism of corrosion of wheel steel corrosion was discussed.

  19. A Novel Energy Recovery System for Parallel Hybrid Hydraulic Excavator

    OpenAIRE

    Li, Wei; Cao, Baoyu; Zhu, Zhencai; Chen, Guoan

    2014-01-01

    Hydraulic excavator energy saving is important to relieve source shortage and protect environment. This paper mainly discusses the energy saving for the hybrid hydraulic excavator. By analyzing the excess energy of three hydraulic cylinders in the conventional hydraulic excavator, a new boom potential energy recovery system is proposed. The mathematical models of the main components including boom cylinder, hydraulic motor, and hydraulic accumulator are built. The natural frequency of the pro...

  20. A STRUCTURAL MODEL OF AN EXCAVATOR WORKFLOW CONTROL SYSTEM

    Directory of Open Access Journals (Sweden)

    A. Gurko

    2016-12-01

    Full Text Available Earthwork improving is connected with excavators automation. In this paper, on the basis of the analysis of problems that a hydraulic excavator control system have to solve, the hierarchical structure of a control system have been proposed. The decomposition of the control process had been executed that allowed to develop the structural model which reflects the characteristics of a multilevel space-distributed control system of an excavator workflow.

  1. Pneumatic Excavation Mechanism for Lunar Resource Utilization Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Honeybee Robotics, in collaboration with Firestar Engineering, proposes to continue development of a pneumatic regolith excavating, moving and heating approach. With...

  2. Focal Choroidal Excavation in Best Vitelliform Macular Dystrophy: Case Report.

    Science.gov (United States)

    Esfahani, Mohammad Riazi; Esfahani, Hamid Riazi; Mahmoudi, Alireza; Johari, Mohammad Karim; Hemati, Karim

    2015-05-01

    Focal choroidal excavation (FCE) was first reported as a choroidal posteriorly excavated zone without any scleral change. Choroidal excavation also divided into conforming and nonconforming type. Numerous reports demonstrated association between FCE and other disease such as choroidal neovascularization and central serous choroidoretinopathy. Here, we report a rare case of FCE in a patient with Best disease. The patient was diagnosed by spectoral domain optical coherence tomography (SD-OCT). To the best of our knowledge, our patient is the second report of choroidal excavation in Best vitelliform macular dystrophy.

  3. Theory and technology of rock excavation for civil engineering

    CERN Document Server

    Zou, Dingxiang

    2017-01-01

    This book summarizes the technical advances in recent decades and the various theories on rock excavation raised by scholars from different countries, including China and Russia. It not only focuses on rock blasting but also illustrates a number of non-blasting methods, such as mechanical excavation in detail. The book consists of 3 parts: Basic Knowledge, Surface Excavation and Underground Excavation. It presents a variety of technical methods and data from diverse sources in the book, making it a valuable theoretical and practical reference resource for engineers, researchers and postgraduates alike.

  4. On fan-wheel and tree-wheel Ramsey numbers

    NARCIS (Netherlands)

    Zhang, Yanbo; Zhang, Yanbo; Broersma, Haitze J.; Chen, Yaojun

    2016-01-01

    For graphs G1 and G2, the Ramsey number R(G1,G2) is the smallest integer N such that, for any graph G of order N, G contains G1 as a subgraph or the complement of G contains G2 as a subgraph. Let Tn denote a tree of order n, Wn a wheel of order n+1 and Fn a fan of order 2n+1. We establish Ramsey

  5. Injection Bucket Jitter Compensation Using Phase Lock System at Fermilab Booster

    Energy Technology Data Exchange (ETDEWEB)

    Seiya, K. [Fermilab; Drennan, C. [Fermilab; Pellico, W. [Fermilab; Chaurize, S. [Fermilab

    2017-05-12

    The extraction bucket position in the Fermilab Booster is controlled with a cogging process that involves the comparison of the Booster rf count and the Recycler Ring revolution marker. A one rf bucket jitter in the ex-traction bucket position results from the variability of the process that phase matches the Booster to the Recycler. However, the new slow phase lock process used to lock the frequency and phase of the Booster rf to the Recycler rf has been made digital and programmable and has been modified to correct the extraction notch position. The beam loss at the Recycler injection has been reduced by 20%. Beam studies and the phase lock system will be discussed in this paper.

  6. An Experimental Study of the Drained Capacity of Bucket Foundations for Offshore Applications

    DEFF Research Database (Denmark)

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

    2013-01-01

    Today, wind energy offers the most competitive production prices for renewable energy. Therefore there are strong political and industrial forces, especially in northern Europe, which support the development of the offshore wind industry. The present paper presents the results of drained tests...... on offshore bucket foundations for wind turbines in saturated dense sand. The bearing capacity of bucket foundations subject to combined loadings which are of interest particularly to the offshore geotechnical engineers, were calculated and found to be largely dependent on embedment ratios and load paths....... Based on the results of the analyses, new failure criteria are calibrated for bucket foundations, in contrast to previous studies using the failure envelop e approach which have suggested that yield surface is constant in shape....

  7. Test Procedure for Axially Loaded Bucket Foundations in Sand (Large Yellow Box)

    DEFF Research Database (Denmark)

    Vaitkunaite, Evelina

    This is a practical guide for preparing the soil, running a CPT test, installing a scaled bucket foundation model and running a test in the large yellow sand box cos(Kristina) in the geotechnical laboratory at Aalborg University. The test procedure is used for the examination of statically...... and cyclically axially loaded bucket foundation model In dense sand. The foundation model in scale of approximately 1:10 compared to the prototype size. The guide describes the step-by-step procedure for tests with and without surface pressure. A detailed description of test setup using the large yellow sand box...

  8. Literature review on cyclic lateral loading effects of mono-bucket foundations

    DEFF Research Database (Denmark)

    Kapitanov, Lachezar Rosenov; Duroska, Peter; Quirante, Cesar Antonio Garcia

    2016-01-01

    and consequently cost-effectiveness compared to other common solutions. The long-term cyclic loading can cause degradation of soil-bucket system stiffness, which yields into accumulated and permanent deformations. Despite of the advantages, there is no standard procedure to design the foundation especially...... for assessing the accumulated deformations under environmental longterm loading. However, numerical and semi-empirical methods already used for offshore foundations can be adopted to take into account the effect of cyclic loading on Mono-Buckets. Among them, load-displacement techniques as cyclic p-y curves...

  9. Turbine bucket for use in gas turbine engines and methods for fabricating the same

    Science.gov (United States)

    Garcia-Crespo, Andres

    2014-06-03

    A turbine bucket for use with a turbine engine. The turbine bucket includes an airfoil that extends between a root end and a tip end. The airfoil includes an outer wall that defines a cavity that extends from the root end to the tip end. The outer wall includes a first ceramic matrix composite (CMC) substrate that extends a first distance from the root end to the tip end. An inner wall is positioned within the cavity. The inner wall includes a second CMC substrate that extends a second distance from the root end towards the tip end that is different than the first distance.

  10. Numerical Study of Piping Limits for Installation of Large Diameter Buckets in Layered Sand

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Thilsted, C.L.

    2010-01-01

    The bucket foundations, often referred as ‘suction caissons’, are large cylindrical structures, typically made in steel. The bucket foundations have the potential to be the cost-effective option for offshore wind turbines, if suction assisted penetration is employed. Suction installation may cause...... formation of piping channels, which break down the hydraulic seal and prevent further installation. This paper presents a numerical study of failure limits during suction installation in respect to both homogenous and layered soil profile. A numerical flow analysis is performed to determine the hydraulic...

  11. Investigation of seepage around the bucket skirt during installation in sand

    DEFF Research Database (Denmark)

    Koteras, Aleksandra Katarzyna; Ibsen, Lars Bo

    pressure that will create piping channels at exit, which is near to seabed and to the caisson wall, along bucket wall and at the tip. That is how the limits for suction installation can be assumed. Finally, the critical suction is used for predicting the reduction of penetration resistance and the method...... describing this approach is presented in the report with its assumptions. The method is called AAU CPT-based method and it is a great step in the development of practical design tool for bucket foundation installation process....

  12. Comparison of numerical formulations for the modeling of tensile loaded suction buckets

    DEFF Research Database (Denmark)

    Sørensen, Emil Smed; Clausen, Johan Christian; Damkilde, Lars

    2017-01-01

    The tensile resistance of a suction bucket is investigated using three different numerical formulations. The first formulation utilizes the three-field u-p-U formulation accounting for solid and fluid displacements, u and U, as well as the pore-fluid pressure, p. The two other formulations comprise...... the simpler u-p formulation in its dynamic and quasi-static form, accounting only for solid displacement and pore-fluid pressure. As basis for comparison, the tensile resistance of a single suction bucket is investigated using a velocity-driven model for a wide range of velocities. It is found, that the quasi...

  13. IMPLEMENTASI MANAJEMEN BANDWIDTH DENGAN DISIPLIN ANTRIAN HIERARCHICAL TOKEN BUCKET (HTB PADA SISTEM OPERASI LINUX

    Directory of Open Access Journals (Sweden)

    Muhammad Nugraha

    2017-01-01

    Full Text Available Important Problem on Internet networking is exhausted resource and bandwidth by some user while other user did not get service properly. To overcome that problem we need to implement traffic control and bandwidth management system in router. In this research author want to implement Hierarchical Token Bucket algorithm as queue discipline (qdisc to get bandwidth management accurately in order the user can get bandwidth properly. The result of this research is form the management bandwidth cheaply and efficiently by using Hierarchical Token Bucket qdisc on Linux operating system were able to manage the user as we want.

  14. Flooding and sedimentation in Wheeling Creek basin, Belmont County, Ohio

    Science.gov (United States)

    Kolva, J.R.; Koltun, G.F.

    1987-01-01

    The Wheeling Creek basin, which is located primarily in Belmont County, Ohio, experienced three damaging floods and four less severe floods during the 29-month period from February 1979 through June 1981. Residents of the basin became concerned about factors that could have affected the severity and frequency of out-of-bank floods. In response to those concerns, the U.S. Geological Survey, in cooperation with the Ohio Department of Natural Resources, undertook a study to estimate peak discharges and recurrence intervals for the seven floods of interest, provide information on current and historical mining-related stream-channel fill or scour, and examine storm-period subbasin contributions to the sediment load in Wheeling Creek. Streamflow data for adjacent basins, rainfall data, and, in two cases, flood-profile data were used in conjunction with streamflow data subsequently collected on Wheeling Creek to provide estimates of peak discharge for the seven floods that occurred from February 1979 through June 1981. Estimates of recurrence intervals were assigned to the Peak discharges on the basin of regional regression equations that relate selected basin characteristics to peak discharge with fixed recurrence intervals. These estimates indicate that a statistically unusual number of floods with recurrence intervals of 2 years or more occurred within that time period. Three cross sections located on Wheeling Creek and four located on tributaries were established and surveyed quarterly for approximately 2 years. No evidence of appreciable stream-channel fill or scour was observed at any of the cross sections, although minor profile changes were apparent at some locations. Attempts were made to obtain historical cross-section profile data for comparison with current cross-section profiles; however, no usable data were found. Excavations of stream-bottom materials were made near the three main-stem cross-section locations and near the mouth of Jug Run. The bottom

  15. Focal Choroidal Excavation in Retinal Dystrophies.

    Science.gov (United States)

    Braimah, Imoro Zeba; Rapole, Shruthi; Dumpala, Sunila; Chhablani, Jay

    2016-08-17

    To investigate the presence of focal choroidal excavation (FCE) in patients with retinitis pigmentosa (RP), Stargardt's disease (STGD), and Best disease in the Indian population. This retrospective consecutive case series included 309 eyes of 157 patients with RP (183 eyes), STGD (93 eyes), and Best disease (33 eyes) with good-quality, enhanced-depth spectral domain optical coherence tomography scans. Comprehensive ophthalmic examination data were collected. Characteristics of FCE, including location of FCE, type (conforming and non-conforming), maximal width, and depth, were noted. FCE was found in 2 out of 33 (6%) eyes with Best disease and no FCE was found in eyes with RP or STGD. The location of the FCE was extrafoveal in both cases. The first case had non-conforming FCE while the second case had the conforming type and the FCE occurred in association with choroidal neovascularization in the second case. The first case maintained good visual acuity of 20/20 over the entire period of follow-up (14 months), while the second case had a visual acuity of 20/200 at the last follow-up (three years) due to scarred choroidal neovascular membranes. The FCE showed no change in both eyes over the entire duration of follow-up. Focal choroidal excavation was found in 6% of eyes with Best disease, which remained stable throughout follow up. Eyes with RP and STGD did not have any FCE. Further studies are required to determine the role of vitelliform material in FCE development in Best disease.

  16. Lightweight, Self-Deployable Wheels

    Science.gov (United States)

    Chmielewski, Artur; Sokolowski, Witold; Rand, Peter

    2003-01-01

    Ultra-lightweight, self-deployable wheels made of polymer foams have been demonstrated. These wheels are an addition to the roster of cold hibernated elastic memory (CHEM) structural applications. Intended originally for use on nanorovers (very small planetary-exploration robotic vehicles), CHEM wheels could also be used for many commercial applications, such as in toys. The CHEM concept was reported in "Cold Hibernated Elastic Memory (CHEM) Expandable Structures" (NPO-20394), NASA Tech Briefs, Vol. 23, No. 2 (February 1999), page 56. To recapitulate: A CHEM structure is fabricated from a shape-memory polymer (SMP) foam. The structure is compressed to a very small volume while in its rubbery state above its glass-transition temperature (Tg). Once compressed, the structure can be cooled below Tg to its glassy state. As long as the temperature remains shape. Once thus deployed, the CHEM structure can be rigidified by cooling below Tg to the glassy state. The structure could be subsequently reheated above Tg and recompacted. The compaction/deployment/rigidification cycle could be repeated as many times as needed.

  17. Woodpecker Excavation and Use of Cavities in Polystyrene Snags

    Science.gov (United States)

    Richard N. Conner; Daniel Saenz

    1996-01-01

    We examined woodpecker excavation and use of artificial polystyrene snags in four forest types in eastern Texas for five years. Twenty-three of 47 artificial snags were used by Downy Woodpeckers (Picoides pubescens) for cavity excavation and subsequent nocturnal roosting; they did not use the artificial snags for nesting. Although six ather species of woodpeckers...

  18. Preliminary results of excavations at Lincoln Cave, Sterkfontein, South Africa

    CSIR Research Space (South Africa)

    Reynolds, SC

    2003-05-01

    Full Text Available Recent excavations of undisturbed deposits within the Lincoln Cave, Sterkfontein, have conclusively demonstrated that at least one of the deposits is mid-late Pleistocene in age. The artefacts recovered from this excavation are in a datable context...

  19. Reaction wheels for kinetic energy storage

    Science.gov (United States)

    Studer, P. A.

    1984-01-01

    In contrast to all existing reaction wheel implementations, an order of magnitude increase in speed can be obtained efficiently if power to the actuators can be recovered. This allows a combined attitude control-energy storage system to be developed with structure mounted reaction wheels. The feasibility of combining reaction wheels with energy storage wwheels is demonstrated. The power required for control torques is a function of wheel speed but this energy is not dissipated; it is stored in the wheel. The I(2)R loss resulting from a given torque is shown to be constant, independent of the design speed of the motor. What remains, in order to efficiently use high speed wheels (essential for energy storage) for control purposes, is to reduce rotational losses to acceptable levels. Progress was made in permanent magnet motor design for high speed operation. Variable field motors offer more control flexibility and efficiency over a broader speed range.

  20. Aerodynamic Drag Reduction Apparatus For Wheeled Vehicles In Ground Effect

    Science.gov (United States)

    Ortega, Jason M.; Salari, Kambiz

    2005-12-13

    An apparatus for reducing the aerodynamic drag of a wheeled vehicle in a flowstream, the vehicle having a vehicle body and a wheel assembly supporting the vehicle body. The apparatus includes a baffle assembly adapted to be positioned upstream of the wheel assembly for deflecting airflow away from the wheel assembly so as to reduce the incident pressure on the wheel assembly.

  1. Flow simulation of a Pelton bucket using finite volume particle method

    Science.gov (United States)

    Vessaz, C.; Jahanbakhsh, E.; Avellan, F.

    2014-03-01

    The objective of the present paper is to perform an accurate numerical simulation of the high-speed water jet impinging on a Pelton bucket. To reach this goal, the Finite Volume Particle Method (FVPM) is used to discretize the governing equations. FVPM is an arbitrary Lagrangian-Eulerian method, which combines attractive features of Smoothed Particle Hydrodynamics and conventional mesh-based Finite Volume Method. This method is able to satisfy free surface and no-slip wall boundary conditions precisely. The fluid flow is assumed weakly compressible and the wall boundary is represented by one layer of particles located on the bucket surface. In the present study, the simulations of the flow in a stationary bucket are investigated for three different impinging angles: 72°, 90° and 108°. The particles resolution is first validated by a convergence study. Then, the FVPM results are validated with available experimental data and conventional grid-based Volume Of Fluid simulations. It is shown that the wall pressure field is in good agreement with the experimental and numerical data. Finally, the torque evolution and water sheet location are presented for a simulation of five rotating Pelton buckets.

  2. Energy Bucket: A Tool for Power Profiling and Debugging of Sensor Nodes

    DEFF Research Database (Denmark)

    Andersen, Jacob; Hansen, Morten Tranberg

    2009-01-01

    of current draw. The Energy Bucket provides a light-weight state API for the target system, which facilitates easy scorekeeping of energy consumption between different parts of a target program. We demonstrate how this tool can be used to discover programming errors and debug sensor network applications...

  3. Assessment of measurement errors and dynamic calibration methods for three different tipping bucket rain gauges

    Science.gov (United States)

    Three different models of tipping bucket rain gauges (TBRs), viz. HS-TB3 (Hydrological Services Pty Ltd), ISCO-674 (Isco, Inc.) and TR-525 (Texas Electronics, Inc.), were calibrated in the lab to quantify measurement errors across a range of rainfall intensities (5 mm.h-1 to 250 mm.h-1) and three di...

  4. Measuring water and sediment discharge from a road plot with a settling basin and tipping bucket

    Science.gov (United States)

    Thomas A. Black; Charles H. Luce

    2013-01-01

    A simple empirical method quantifies water and sediment production from a forest road surface, and is well suited for calibration and validation of road sediment models. To apply this quantitative method, the hydrologic technician installs bordered plots on existing typical road segments and measures coarse sediment production in a settling tank. When a tipping bucket...

  5. Buckling of Monopod Bucket Foundations – Influence of Boundary Conditions and Soil-structure Interaction

    DEFF Research Database (Denmark)

    Madsen, Søren; Pinna, Rodney; Randolph, M. F.

    2015-01-01

    of large-diameter bucket foundations. Since shell structures are generally sensitive to initially imperfect geometries, eigenmode-affine imperfections are introduced in a nonlinear finite-element analysis. The influence of modelling the real lid structure compared to classic boundary conditions...

  6. Observations on bucket foundations under cyclic loading in dense saturated sand

    DEFF Research Database (Denmark)

    Foglia, Aligi; Ibsen, Lars Bo; Nicolai, Giulio

    2014-01-01

    Offshore wind farms will play a significant role in the European energy supply of the coming years. Today, one of the main challenges faced by the offshore wind market is to reduce the cost of turbine foundations. The monopod bucket foundation is a possible solution to this problem. The long...

  7. The tale of two buckets and associated containers: impact on aedes albopictus oviposition

    Science.gov (United States)

    Aedes albopictus is an invasive species. Its oviposition behavior is the subject of several projects in our research unit. The main emphasis of this presentation is a study which utilizes two five gallon buckets, one heated and one with ambient temperature. The heat is provided by an aquarium hea...

  8. Multi-bucket optimization for integrated planning and scheduling in the perishable dairy supply chain

    NARCIS (Netherlands)

    Sel, C.; Bilgen, B.; Bloemhof, J.M.; Vorst, van der J.G.A.J.

    2015-01-01

    This paper considers a dairy industry problem on integrated planning and scheduling of set yoghurt production. A mixed integer linear programming formulation is introduced to integrate tactical and operational decisions and a heuristic approach is proposed to decompose time buckets of the decisions.

  9. Literature review on cyclic lateral loading effects of mono-bucket foundations

    DEFF Research Database (Denmark)

    Kapitanov, Lachezar Rosenov; Duroska, Peter; Quirante, Cesar Antonio Garcia

    2016-01-01

    calculation is highly demanded at the different design phases. The intention of the current study is to present, review and summarize the existing techniques to assess the effect of cyclic loading on Mono-Bucket foundations while emphasizing the advantage and disadvantage of each of them. Additionally...

  10. Dynamic behaviour of mono bucket foundations subjected to combined transient loading

    DEFF Research Database (Denmark)

    Nielsen, Søren Dam; Ibsen, Lars Bo; Nielsen, Benjaminn Nordahl

    2015-01-01

    This article presents the results from small scale testing, investigating the effect of transient combined loading of a bucketfoundation. The tests are performed inside a pressure tank at Aalborg University, Denmark. The bucket foundation was installed in dense water saturated sand and transient ...

  11. Unsteady aerodynamics of single and tandem wheels

    OpenAIRE

    Spagnolo, Stefano; Zhang, Xin; Hu, Zhiwei; Stalnov, Oksana; Angland, David

    2017-01-01

    The major unsteady aerodynamic forces and major physics of a generic single wheel and tandem wheels are studied for the first time using wind tunnel tests. The wind-tunnel tests are performed in the 2.1 m × 1.5 m wind tunnel at the University of Southampton. The tandem-wheel configuration consists of two in-line wheels that can be tested at different inter-axis distances and various installation angles. A vibration test is performed in situ on the model assembly to validate the unsteady-load ...

  12. ATLAS- lowering the muon small wheel

    CERN Multimedia

    CERN Audiovisual Service

    2008-01-01

    ATLAS - the two muon small wheels lowered into the cavern Like briefly separated twin sisters, ATLAS’s small wheels were once again united at the experiment’s surface building at Point 1 on St Valentine’s Day. The lowering of the small wheels into the tunnel will mark the end of the installation of detector components for the experiment. At around 15.40 on Friday 29th February the ATLAS collaboration cracked open the champagne as the second of the small wheels was lowered into the cavern.

  13. Origami Wheel Transformer: A Variable-Diameter Wheel Drive Robot Using an Origami Structure.

    Science.gov (United States)

    Lee, Dae-Young; Kim, Sa-Reum; Kim, Ji-Suk; Park, Jae-Jun; Cho, Kyu-Jin

    2017-06-01

    A wheel drive mechanism is simple, stable, and efficient, but its mobility in unstructured terrain is seriously limited. Using a deformable wheel is one of the ways to increase the mobility of a wheel drive robot. By changing the radius of its wheels, the robot becomes able to pass over not only high steps but also narrow gaps. In this article, we propose a novel design for a variable-diameter wheel using an origami-based soft robotics design approach. By simply folding a patterned sheet into a wheel shape, a variable-diameter wheel was built without requiring lots of mechanical parts and a complex assembly process. The wheel's diameter can change from 30 to 68 mm, and it is light in weight at about 9.7 g. Although composed of soft materials (fabrics and films), the wheel can bear more than 400 times its weight. The robot was able to change the wheel's radius in response to terrain conditions, allowing it to pass over a 50-mm gap when the wheel is shrunk and a 50-mm step when the wheel is enlarged.

  14. The displaced bucket-handle tear of the meniscus: MRI findings

    Energy Technology Data Exchange (ETDEWEB)

    Park, Gyung Hi; Juhng, Seon Kwan; Kim, Gang Deuk; Kwon, Young Mi; Won, Jong Jin [Wonkwang University School of Medicine, Iri (Korea, Republic of)

    1994-07-15

    To describe the features of displaced bucket-handle tears of the menisci on magnetic resonance(MR) images and to assess associated knee injuries. We retrospectively reviewed coronal and sagittal MR images in 21 bucket-handle tears. The subjects were patients who had underwent preoperative MR evaluations of the knee and were identified from the arthroscopic surgical records as bucket-handle tear. We also described patterns of associated injuries. On coronal MR images, (a) in all cases, peripheral portion of the meniscus(bucket) had the appearance of a truncated or altered wedge; (b) central fragments(handle) were observed to be sitting in the intercondylar notch (16 cases) or located between the femoral condyle and tibial plateau (5 cases). On sequential sagittal MR images, (c) the bow-tie appearance of the body of the meniscus was not seen (13 cases); (d) the bow-tie appearance of the displaced inner fragment was seen at the intercondylar notch level (9 cases); (e) 'double posterior cruciate ligament' sign was presented (7 cases). Associated joint abnormalities included anterior cruciate ligament tears(11), contralateral meniscal tears(11), posterior cruciate ligament tears(3), medial collateral ligament tears(3), osteoarthritis(1), and Baker's cyst(1). Awareness of these characteristic MR images(a-e) may increase the sensitivity of MR imaging in the diagnosis of displaced bucket-handle tears, and the MRI may be helpful to correctly characterize the displaced fragment and patterns of associated injury, providing arthroscopists a guide to appropriate surgical plans.

  15. Bucket handle tears of the medial meniscus: meniscal intrusion rather than meniscal extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Schlossberg, S. [Jacobi Medical Center, Department of Radiology, Bronx, NY (United States); Umans, H. [Jacobi Medical Center, Department of Radiology, Bronx, NY (United States); Jacobi Medical Center, Department of Surgery Division of Orthopedic Surgery, Bronx, NY (United States); Flusser, G. [Tel Aviv Sourasky Medical Center, Department of Radiology, Tel Aviv (Israel); DiFelice, G.S. [Jacobi Medical Center, Department of Surgery Division of Orthopedic Surgery, Bronx, NY (United States); Lerer, D.B. [Montefiore Medical Center, Department of Radiology, Bronx, NY (United States)

    2007-01-15

    To determine the frequency of medial meniscal extrusion (MME) versus ''medial meniscal intrusion'' in the setting of bucket handle tears. Images were evaluated for previously reported risk factors for MME, including: medial meniscal root tear, radial tear, degenerative joint disease and joint effusion. Forty-one consecutive cases of bucket handle tear of the medial meniscus were reviewed by consensus by two musculoskeletal radiologists. Imaging was performed using a 1.5 GE Signa MR unit. Patient age, gender, medial meniscal root integrity, MME, medial meniscal intrusion, degenerative joint disease, effusion and anterior cruciate ligament (ACL) tear were recorded. Thirteen females and 27 males (age 12-62 years, median=30 years) were affected; one had bucket handle tear of each knee. Effusion was small in 13, moderate in 9 and large in 18. Degenerative joint disease was mild in three, moderate in two and severe in one. 26 ACL tears included three partial and three chronic. Medial meniscal root tear was complete in one case and partial thickness in two. None of the 40 cases with an intact or partially torn medial meniscal root demonstrated MME. MME of 3.1 mm was seen in the only full-thickness medial meniscal root tear, along with chronic ACL tear, moderate degenerative joint disease and large effusion. Medial meniscal intrusion of the central bucket handle fragment into the intercondylar notch was present in all 41 cases. Given an intact medial meniscal root in the setting of a ''pure'' bucket handle tear, there is no MME. (orig.)

  16. SABRE: A Sensitive Attribute Bucketization and REdistribution framework for t-closeness

    KAUST Repository

    Cao, Jianneng

    2010-05-19

    Today, the publication of microdata poses a privacy threat: anonymous personal records can be re-identified using third data sources. Past research has tried to develop a concept of privacy guarantee that an anonymized data set should satisfy before publication, culminating in the notion of t-closeness. To satisfy t-closeness, the records in a data set need to be grouped into Equivalence Classes (ECs), such that each EC contains records of indistinguishable quasi-identifier values, and its local distribution of sensitive attribute (SA) values conforms to the global table distribution of SA values. However, despite this progress, previous research has not offered an anonymization algorithm tailored for t-closeness. In this paper, we cover this gap with SABRE, a SA Bucketization and REdistribution framework for t-closeness. SABRE first greedily partitions a table into buckets of similar SA values and then redistributes the tuples of each bucket into dynamically determined ECs. This approach is facilitated by a property of the Earth Mover\\'s Distance (EMD) that we employ as a measure of distribution closeness: If the tuples in an EC are picked proportionally to the sizes of the buckets they hail from, then the EMD of that EC is tightly upper-bounded using localized upper bounds derived for each bucket. We prove that if the t-closeness constraint is properly obeyed during partitioning, then it is obeyed by the derived ECs too. We develop two instantiations of SABRE and extend it to a streaming environment. Our extensive experimental evaluation demonstrates that SABRE achieves information quality superior to schemes that merely applied algorithms tailored for other models to t-closeness, and can be much faster as well. © 2010 Springer-Verlag.

  17. System for opening and mining stratified and rock embedded deposits by means of discontinuous loading and continuous haulage of excavated material. Sistem otkrivanja i eksploatacije slojeva lezista u cvrstim stijenama uz primjenu diskontinuiranog utovara i kontinuiranog transporta iskopine

    Energy Technology Data Exchange (ETDEWEB)

    0Voncina, Z.; Tanackovic, S.; Hamidovic, F. (Rudis, Ljubljana (Yugoslavia))

    1990-01-01

    Presents project features of a mobile crusher designed by the Tuzla Mining Institute and the Rudis Design Bureau in Ljubljana. The crusher is to be employed in coal or ore surface mines with rock spoil. A crusher unit ensures higher production by shovel excavators and draglines, reduces operating cost, achieves better utilization of belt conveyors and build-up of higher mine benches. The crusher is designed for operation in configuration with shovel excavators, hydraulic excavators, draglines and wheel loaders, and crushes blasted rock for haulage on belt conveyors. Three model sizes of this crushing unit are proposed for manufacturing: a unit with 1,000 t/h capacity, one with 1-2,500 t/h and the largest with 2,000-3,500 t per unit. A scheme of equipment design is provided.

  18. MR imaging of meniscal bucket-handle tears: a review of signs and their relation to arthroscopic classification

    Energy Technology Data Exchange (ETDEWEB)

    Aydingoez, Uestuen; Firat, Ahmet K. [Department of Radiology, Hacettepe University Medical Center, 06100 Ankara (Turkey); Atay, Ahmet Oe.; Doral, Nedim M. [Department of Orthopaedics and Traumatology, Hacettepe University Medical Center, 06100 Ankara (Turkey)

    2003-03-01

    Our objective was to review the MR imaging signs of meniscal bucket-handle tears and assess the relevance of these signs to the arthroscopic classification of displaced meniscal tears. Forty-five menisci in 42 patients who had a diagnosis of bucket-handle tear either on MR imaging or on subsequent arthroscopy (in which Dandy's classification of meniscal tears was used) were retrospectively analyzed for MR imaging findings of double posterior cruciate ligament (PCL), fragment within the intercondylar notch, absent bow tie, flipped meniscus, double-anterior horn, and disproportional posterior horn signs. Arthroscopy, which was considered as the gold standard, revealed 41 bucket-handle tears (either diagnosed or not diagnosed by MR imaging) in 38 patients (33 males, 5 females). There was a stastistically significant male preponderance for the occurrence of meniscal bucket-handle tears. Overall, sensitivity and positive predictive value of MR imaging for the detection of meniscal bucket-handle tears were calculated as 90%. Common MR imaging signs of meniscal bucket-handle tears in arthroscopically proven cases of such tears were the fragment in the notch and absent bow tie signs (98% frequency for each). Double-PCL, flipped meniscus, double-anterior horn, and disproportional posterior horn signs, however, were less common (32, 29, 29, and 27%, respectively). An arthroscopically proven bucket-handle tear was found in all patients who displayed at least three of the six MR imaging signs of meniscal bucket-handle tears. The presence of three or more MR imaging signs of meniscal bucket-handle tears is highly suggestive of this condition. (orig.)

  19. FOCAL CHOROIDAL EXCAVATION AND CHOROIDAL NEOVASCULARIZATION WITH ASSOCIATED PACHYCHOROID.

    Science.gov (United States)

    Ghadiali, Quraish; Dansingani, Kunal K; Freund, K Bailey

    2016-01-01

    To report a case of focal choroidal excavation and choroidal neovascularization in the setting of pachychoroid disease. Multimodal imaging, including fundus photography, fundus autofluorescence, enhanced depth imaging optical coherence tomography, indocyanine green angiography, and en face structural and angiographic optical coherence tomography. The authors describe a 39-year-old female with moderately high myopia presenting with focal choroidal excavation and associated choroidal neovascularization. Multimodal imaging demonstrated pachychoroid features with dilated choroidal vessels surrounding the lesion. Optical coherence tomography angiography showed Type 2 neovascularization. Some cases of focal choroidal excavation and associated neovascularization may be related to structural abnormalities of the associated choroidal vasculature.

  20. A Gigantic Molecular Wheel of {Gd140}: A New Member of the Molecular Wheel Family.

    Science.gov (United States)

    Zheng, Xiu-Ying; Jiang, You-Hong; Zhuang, Gui-Lin; Liu, Da-Peng; Liao, Hong-Gang; Kong, Xiang-Jian; Long, La-Sheng; Zheng, Lan-Sun

    2017-12-20

    Nanoscale inorganic wheel-shaped structures are one of the most striking types of molecular aggregations. Here, we report the synthesis of a gigantic lanthanide wheel cluster containing 140 Gd 3+ atoms. As the largest lanthanide cluster reported thus far, {Gd 140 } features an attractive wheel-like structure with 10-fold symmetry. The nanoscopic molecular wheel possesses the largest diameter of 6.0 nm and displays high stability in solution, which allows direct visualization by scanning transmission electron microscopy. The newly discovered lanthanide {Gd 140 } cluster represents a new member of the molecular wheel family.

  1. Determination of p-y Curves using Finite Element Modelling for Bucket Foundation in Undrained Soft and Medium Clay

    DEFF Research Database (Denmark)

    Hvidberg, Mogens Bonde; Ibsen, Lars Bo

    In many years the types of foundation, such as monopiles and bucket foundation which are used in the offshore wind turbine industry, have been analysed analytically with formulations that are based on much slender piles, than are used today. Because of that, the analytical calculation...... is not describing the connection between the horizontal bearing capacity of the soil and the displacement of the foundation accurate, in particular for the bucket foundation because of the much smaller slenderness of the profile. Numerical modelling is used to examine that bearing capacity the bucket foundation has...

  2. Chemomechanical Excavation is More Time-consuming Than Rotary, but not Necessarily Hand Excavation.

    Science.gov (United States)

    Schwendicke, Falk

    2015-12-01

    Systematic review and meta-analysis of randomized clinical trials on chemomechanical caries removal. Hamama, H., et al.Oper Dent 2015;40(4):E167-178. Falk Schwendicke, DDS, PhD PURPOSE/QUESTION: How valid were the methodologies of studies on chemomechnical caries removal, and is chemomechanical caries removal more time-consuming than conventional hand or rotary excavation? Information not available Systematic review with meta-analysis of data Level 3: Other evidence Grade C (no patient-centered/relevant outcomes). Copyright © 2015 Elsevier Inc. All rights reserved.

  3. REINVENTING THE WHEEL: Comparison of Two Wheel Cage Styles for Assessing Mouse Voluntary Running Activity.

    Science.gov (United States)

    Seward, Tanya; Harfmann, Brianna D; Esser, Karyn A; Schroder, Elizabeth A

    2017-12-21

    Voluntary wheel cage assessment of mouse activity is commonly employed in exercise and behavioral research. Currently, no standardization for wheel cages exists resulting in an inability to compare results among data from different labs. The purpose of this study was to determine whether the distance run or average speed data differs depending on the use of two commonly used commercially available wheel cage systems. Two different wheel cages with structurally similar but functionally different wheels (electromechanical switch vs magnetic switch) were compared side-by-side to measure wheel running data differences. Other variables, including enrichment and cage location, were also tested to assess potential impacts on the running wheel data. We found that cages with the electromechanical switch had greater inherent wheel resistance and consistently led to higher greater running distance/day and higher average running speed. Mice rapidly, within 1-2 days, adapted their running behavior to the type of experimental switch used suggesting these running differences are more behavioral than due to intrinsic musculoskeletal, cardiovascular or metabolic limits. The presence of enrichment or location of the cage had no detectable impact on voluntary wheel running. These results demonstrate that mice run differing amounts depending on the type of cage and switch mechanism used and thus, investigators need to report wheel cage type/ wheel resistance and use caution when interpreting distance/speed run across studies.

  4. Non-Circular Wheels: Reuleaux and Squares

    Science.gov (United States)

    Mills, Allan

    2011-01-01

    Circular wheels are so familiar on vehicles of all types that it is seldom realized that alternatives do exist. This short non-mathematical article describes Reuleaux and square wheels that, rolling along appropriate tracks, can maintain a moving platform at a constant height. Easily made working models lend themselves to demonstrations at science…

  5. Dynamic and Acoustic Characterisation of Automotive Wheels

    Directory of Open Access Journals (Sweden)

    Francesca Curà

    2004-01-01

    Full Text Available The subject of this paper is the dynamic and acoustic characterisation of an automotive wheel. In particular, an experimental research activity previously performed by the authors about the dynamic behaviour of automotive wheels has been extended to the acoustic field.

  6. A Full Disturbance Model for Reaction Wheels

    NARCIS (Netherlands)

    Le, M.P.; Ellenbroek, Marcellinus Hermannus Maria; Seiler, R; van Put, P.; Cottaar, E.J.E.

    2014-01-01

    Reaction wheels are rotating devices used for the attitude control of spacecraft. However, reaction wheels also generate undesired disturbances in the form of vibrations, which may have an adverse effect on the pointing accuracy and stability of spacecraft (optical) payloads. A disturbance model for

  7. Riding the Ferris Wheel: A Sinusoidal Model

    Science.gov (United States)

    Mittag, Kathleen Cage; Taylor, Sharon E.

    2011-01-01

    When thinking of models for sinusoidal waves, examples such as tides of the ocean, daily temperatures for one year in your town, light and sound waves, and certain types of motion are used. Many textbooks [1, p. 222] also present a "Ferris wheel description problem" for students to work. This activity takes the Ferris wheel problem out of the…

  8. Quantity of remaining bacteria and cavity size after excavation with FACE, caries detector dye and conventional excavation in vitro.

    Science.gov (United States)

    Lennon, Aine M; Attin, Thomas; Buchalla, Wolfgang

    2007-01-01

    In this in vitro study, quantitative confocal microscopy was used to show differences in the quantity of bacteria remaining in dentin after excavation with different methods. A further parameter was the cavity volume after excavation relative to the original lesion size. Teeth with dentin caries were divided into three groups of 20 each. The caries was removed by a single operator using a slow handpiece and a round bur. In the first group, Fluorescence Aided Caries Excavation (FACE) was carried out: violet light was used to illuminate the operating field and the operator observed the cavity through a high-pass filter and removed the orange-red fluorescing areas. The second group was excavated using Caries Detector, while the third group used conventional excavation. After excavation, cavity volume was measured; samples were stained for bacteria with ethidium bromide, and they were examined using confocal microscopy under standardized conditions. The bound stain was quantified in terms of fluorescence intensity on the confocal images. Total pixel intensity was significantly lower in the FACE Group than in the Caries Detector group (p = 0.046) and in the conventional excavation group (p = 0.021). Differences in cavity volume relative to original lesion size were not statistically significant (p = 0.86, 0.35 and 0.51). Within the limitations of this in vitro study, it can be concluded that FACE is more effective in removing infected dentin without significantly increasing cavity size when compared to conventional excavation and excavation with the aid of caries detector dye.

  9. Omni rotational driving and steering wheel

    DEFF Research Database (Denmark)

    2008-01-01

    Abstract of WO 2008138346  (A1) There is disclosed a driving and steering wheel (112) module (102) with an omni rotational part (106), the module comprising a flange part (104) fixable on a robot, and the omni rotational part (106) comprises an upper omni rotational part (105) and a driving...... and steering wheel part (108), where the omni rotational part (106) is provided for infinite rotation relative to the flange part (104) by both a drive motor (110) and a steering motor (114) being positionable on the flange part (104), and the driving and steering wheel part (108) is suspended from the upper...... omni rotational part (105) with a suspension (116) such that wheel part (108) can move relatively to the upper omni rotational part (105) in a suspension direction (118), and a reduction gear (120) for gearing the drive torque is provided in the wheel part (108) in order e.g. to assure traction...

  10. Impact-Actuated Digging Tool for Lunar Excavation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Honeybee Robotics proposes to develop a vacuum compatible, impact-actuated digging tool for the excavation of frozen and compacted regolith on the lunar surface and...

  11. Double and triple-harmonic RF buckets and their use for bunch squeezing in AGS

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, C. J. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-08-24

    For the past several years we have merged bunches in AGS in order to achieve the desired intensity per bunch prior to injection into RHIC. The merging is done on a flat porch at or above AGS injection energy. Because the merges involve the reduction of the RF harmonic number by a factor of 2 (for a 2 to 1 merge) and then a factor of 3 (for a 3 to 1 merge), one requires RF frequencies 6hfs, 3hfs, 2hfs and hfs, where fs is the revolution frequency on the porch and h = 4 is the fundamental harmonic number. The standard AGS RF cavities cannot operate at the lowest frequencies 2hfs and hfs; these are provided by two modified cavities. Upon completion of the merges, the bunches are sitting in harmonic h buckets. In order to be accelerated they need to be squeezed into harmonic 3h buckets. This is accomplished by producing a double-harmonic bucket in which harmonics h and 2h act in concert, and then a triple-harmonic bucket in which harmonics h, 2h, and 3h act in concert. Simulations have shown that the squeeze presents an acceptance bottleneck which limits the longitudinal emittance that can be put into the harmonic 3h bucket. In this note the areas of the double and triple-harmonic buckets are calculated explicitly, and it is shown that these go through a minimum as the RF voltages are raised to the desired values. Several RF voltage ranges are examined, and the acceptance bottleneck is determined for each of these. Finally, the acceptance bottleneck for Au77+ bunches in AGS is calculated for several RF voltage ranges. The main result is that the RF voltages for the low-frequency harmonic h and 2h cavities both must be at least 22 kV in order to achieve an acceptance of 0:6 eV s per nucleon. If the harmonic h and 2h voltages are 15 and 22 kV, respectively, then the acceptance is reduced to 0:548 eV s per nucleon.

  12. Biaxial wheel/hub test facility. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, G.; Grubisic, V. [eds.

    2000-07-01

    The 4{sup th} meeting aims to exchange the experience and knowledge of engineers during several presentations and discussions about new developments required for a reliable, time and cost reducing validation of the wheel/hub assembly. Tremendous development of the wheel performance, described by the ratio of the rated load (kg) versus the wheel weight (kg) had taken place during the last 5000 years. Starting from the ratio of 3 for wooden 2-piece-disc-wheels in Mesopotamia it needed nearly 1000 years to increase the ratio to approx 5 at light-weight spoke wheels for fighting carriages, found in the grave of king Tutenchamon in Egypt. Modern light alloy wheels of commercial vehicles reach values up to 160 kg/kg. Additionally the comlex design of the modern systems for cars and commercial vehicles comprising wheel, brake, hub, bearing, spindle and hub carrier, including different materials and their treatment, fasteners, press-fits, require an appropriate testing procedure. The variable loading conditions, caused by operational wheel forces, brake and torque moments including heating, may result in changing tolerances and press-fits during operation and consequently in different damage mechanisms. This can be simulated in the Biaxial Wheel Test Machine, whereby corresponding load programs are necessary. An overview about all biaxial test machines in usage at the end of 1999 is shown in the introduction. The total number is 17 for cars, 7 for commercial vehicles and 1 for trains. The six presentations of this meeting were consequently concentrated on: (a) recommendations for a standardization of load programs of the German Wheel Committee, (b) the simulation of brake and torque events and (c) the possibility for a numerical stress analyses and fatigue life assessment. (orig./AKF)

  13. Telerobotic Excavator Designed to Compete in NASA's Lunabotics Mining Competition

    Science.gov (United States)

    Nash, Rodney; Santin, Cara; Yousef, Ahmed; Nguyen, Thien; Helferty, John; Pillapakkam, Shriram

    2011-01-01

    The second annual NASA Lunabotics Mining competition is to be held in May 23-28, 2011. The goal of the competition is for teams of university level students to design, build, test and compete with a fully integrated lunar excavator on a simulated lunar surface. Our team, named Lunar Solutions I, will be representing Temple University's College of Engineering in the competition. The team's main goal was to build a robot which is able to compete with other teams, and ultimately win the competition. The main challenge of the competition was to build a wireless robot that can excavate and collect a minimum of 10 kilograms of the regolith material within 15 minutes. The robot must also be designed to operate in conditions similar to those found on the lunar surface. The design of the lunar excavator is constrained by a set of requirements determined by NASA and detailed in the competition's rulebook. The excavator must have the ability to communicate with the "main base" wirelessly, and over a Wi-Fi network. Human operators are located at a remote site approximately 60 meters away from the simulated lunar surface upon which the robot must excavate the lunar regolith surface. During the competition, the robot will operate in a separate area from the control room in an area referred to as the "Lunarena." From the control room, the operators will have to control the robot using visual feedback from cameras placed both within the arena and on the robot. Using this visual feedback the human operators control the robots movement using both keyboard and joystick commands. In order to place in the competition, a minimum of 10 kg of regolith material has to be excavated, collected, and dumped into a specific location. For that reason, the robot must be provided with an effective and powerful excavation system. Our excavator uses tracks for the drive system. After performing extensive research and trade studies, we concluded that tracks would be the most effective method for

  14. Impact-Actuated Digging Tool for Lunar Excavation

    Science.gov (United States)

    Wilson, Jak; Chu, Philip; Craft, Jack; Zacny, Kris; Santoro, Chris

    2013-01-01

    NASA s plans for a lunar outpost require extensive excavation. The Lunar Surface Systems Project Office projects that thousands of tons of lunar soil will need to be moved. Conventional excavators dig through soil by brute force, and depend upon their substantial weight to react to the forces generated. This approach will not be feasible on the Moon for two reasons: (1) gravity is 1/6th that on Earth, which means that a kg on the Moon will supply 1/6 the down force that it does on Earth, and (2) transportation costs (at the time of this reporting) of $50K to $100K per kg make massive excavators economically unattractive. A percussive excavation system was developed for use in vacuum or nearvacuum environments. It reduces the down force needed for excavation by an order of magnitude by using percussion to assist in soil penetration and digging. The novelty of this excavator is that it incorporates a percussive mechanism suited to sustained operation in a vacuum environment. A percussive digger breadboard was designed, built, and successfully tested under both ambient and vacuum conditions. The breadboard was run in vacuum to more than 2..times the lifetime of the Apollo Lunar Surface Drill, throughout which the mechanism performed and held up well. The percussive digger was demonstrated to reduce the force necessary for digging in lunar soil simulant by an order of magnitude, providing reductions as high as 45:1. This is an enabling technology for lunar site preparation and ISRU (In Situ Resource Utilization) mining activities. At transportation costs of $50K to $100K per kg, reducing digging forces by an order of magnitude translates into billions of dollars saved by not launching heavier systems to accomplish excavation tasks necessary to the establishment of a lunar outpost. Applications on the lunar surface include excavation for habitats, construction of roads, landing pads, berms, foundations, habitat shielding, and ISRU.

  15. Dépistage de grandes excavations papillaires dans la population ...

    African Journals Online (AJOL)

    Objectif : Décrire les caractéristiques de l'excavation papillaire et déterminer la prévalence de grandes excavations papillaires dans une population jeune mélanoderme. Patients et Méthodes : Il s'agit d'une étude de population conduite dans des agglomérations rurales du district de Bassar au Nord du Togo où la ...

  16. Choroidal Excavation in Eye with Normal Tension Glaucoma

    Directory of Open Access Journals (Sweden)

    Kazunobu Asao

    2014-05-01

    Full Text Available Purpose: To report the case of an eye with normal tension glaucoma and a choroidal excavation. Methods: This is an observational case report. Results: A 59-year-old woman with normal tension glaucoma had a choroidal excavation in the left eye. Her best-corrected visual acuity and intraocular pressure were within normal limits and had been stable for 5 years. Fundus examination showed a small white lesion inferior to the macula and a nerve fiber layer defect at the inferior edge of the optic disc. Humphrey Field Analyzer (HFA showed visual field defects corresponding to the nerve fiber layer defect with C30-2, and a central scotoma superior to the macula with C10-2. Optical coherence tomography (OCT showed a 150-µm deep choroidal excavation. Disruptions of the IS/OS line were detected only in the area inferior to the choroidal excavation. During the 5 months of follow-up, her best-corrected visual acuity remained at 1.0 and the IOP ranged from 12 to 14 mm Hg in the left eye. The fundus and OCT images did not deteriorate and the choroidal excavation did not enlarge. Conclusions: The disruption of the inner/outer segment (IS/OS line was detected only at the area surrounding the choroidal excavation. OCT examinations are useful in assessing the area of the residual IS/OS line, and HFA can be used to estimate the residual central visual field.

  17. Another Form of Focal Choroidal Excavation Based on Multimodality Imaging.

    Science.gov (United States)

    Wang, Shiyuan; Zhao, Peiquan

    2016-10-01

    To describe a peculiar choroidal entity using multimodality imaging and to further understand the relationship between focal choroidal excavation and central serous chorioretinopathy. A peculiar entity was detected in both eyes of a 20-year-old male patient who was followed for more than 4 years; one perifoveal focal choroidal excavation and two extrafoveal focal choroidal excavations were noted in each eye. The bilateral perifoveal focal choroidal excavations exhibited progressive development with repeated interconversion between the nonconforming and conforming types. Dilated choroid blood vessels were detected by en face spectral-domain optical coherence tomography (SD-OCT). Although the ellipsoid zone and retinal pigment epithelium layer defect also involved the fovea, a visual acuity of 20/20 was maintained in both eyes, with neither metamorphopsia by Amsler grid nor abnormalities noted by multifocal electroretinogram. However, pigment epithelium detachment finally appeared in the right eye. The microperimetry test revealed reduced threshold sensitivity corresponding to the lesions, and near-infrared autofluorescence revealed increased hyperfluorescence at the latest visit. Idiopathic focal choroidal excavation may convert to the structure of central serous chorioretinopathy alike, which likely indicates another rare condition of focal choroidal excavation or central serous chorioretinopathy. Wide- and deep-scanning modes should be routinely applied in OCT imaging to detect choroidal disorders.

  18. Choroidal excavation in vogt-koyanagi-harada disease.

    Science.gov (United States)

    Hashida, Noriyasu; Fok, Andrew; Nishida, Kohji

    2014-05-01

    To report a case of choroidal excavation accompanied by Vogt-Koyanagi-Harada disease (VKH). A 54-year-old Japanese woman who was complaining of bilateral blurring of vision associated with headache underwent optical coherence tomography (OCT), fluorescein angiography, and indocyanine green angiography as well as a routine ophthalmological examination. Fundoscopy showed papilloedema and serous retinal detachment in both eyes. Fluorescein angiography detected bilateral multifocal leakage with pooling of dye in the subretinal space. Indocyanine green angiography showed patches of hyperfluorescence and hypofluorescent spots bilaterally. A diagnosis of VKH was reached soon afterwards. OCT of the left eye revealed the presence of a unilateral choroidal excavation under the fovea and subretinal fibrin over the site of the excavation. Treatment successfully resolved VKH symptoms with gradual resolution of subretinal fibrin and fluid; however, the choroidal excavation remained. This case is the first report of choroidal excavation associated with VKH. Our results suggest that choroidal excavation can be induced by choroidal inflammation caused by VKH.

  19. Choroidal excavation in eye with normal tension glaucoma.

    Science.gov (United States)

    Asao, Kazunobu; Morimoto, Takeshi; Nakada, Atsuko; Kawasaki, Yoshimi

    2014-05-01

    To report the case of an eye with normal tension glaucoma and a choroidal excavation. This is an observational case report. A 59-year-old woman with normal tension glaucoma had a choroidal excavation in the left eye. Her best-corrected visual acuity and intraocular pressure were within normal limits and had been stable for 5 years. Fundus examination showed a small white lesion inferior to the macula and a nerve fiber layer defect at the inferior edge of the optic disc. Humphrey Field Analyzer (HFA) showed visual field defects corresponding to the nerve fiber layer defect with C30-2, and a central scotoma superior to the macula with C10-2. Optical coherence tomography (OCT) showed a 150-µm deep choroidal excavation. Disruptions of the IS/OS line were detected only in the area inferior to the choroidal excavation. During the 5 months of follow-up, her best-corrected visual acuity remained at 1.0 and the IOP ranged from 12 to 14 mm Hg in the left eye. The fundus and OCT images did not deteriorate and the choroidal excavation did not enlarge. The disruption of the inner/outer segment (IS/OS) line was detected only at the area surrounding the choroidal excavation. OCT examinations are useful in assessing the area of the residual IS/OS line, and HFA can be used to estimate the residual central visual field.

  20. Greenhouse Gas Emissions from Excavation on Residential Construction Sites

    Directory of Open Access Journals (Sweden)

    Perry Forsythe

    2014-12-01

    Full Text Available Despite considerable research concerning the manifestation of greenhouse gases in the usage of buildings, little has been done concerning emissions arising from the construction process itself. This paper specifically examines emissions arising from cut and fill excavation on residential construction sites. Even though such excavation is often seen as being economical in terms of providing a flat base for concrete raft slab construction, the environmental consequences of this approach need to be considered more fully in terms of impact on the environment. This is particularly important when steeply sloping sites are involved and for different soil types. The paper undertakes a study that quantitatively assesses the cumulative greenhouse gas emissions caused by cut and fill excavation on 52 residential projects in Australia for a range of slope and soil types. The paper presents results from the study and concludes that greenhouse gas emissions increase as site slope increases; the building footprint area (as distinct from Gross Floor Area, exposes the need to reduce the area of the building to reduce greenhouse gas emissions; excavation of rock soils creates higher emissions than other soil types; and cut and fill excavation on steeply slope sites increase emissions. Potential alternative construction includes suspended floor construction systems which involve less excavation.

  1. Greenhouse Gas Emissions from Excavation on Residential Construction Sites

    Directory of Open Access Journals (Sweden)

    Perry Forsythe

    2014-12-01

    Full Text Available Despite considerable research concerning the manifestation of greenhouse gases in the usage of buildings, little has been done concerning emissions arising from the construction process itself. This paper specifically examines emissions arising from cut and fill excavation on residential construction sites. Even though such excavation is often seen as being economical in terms of providing a flat base for concrete raft slab construction, the environmental consequences of this approach need to be considered more fully in terms of impact on the environment. This is particularly important when steeply sloping sites are involved and for different soil types. The paper undertakes a study that quantitatively assesses the cumulative greenhouse gas emissions caused by cut and fill excavation on 52 residential projects in Australia for a range of slope and soil types. The paper presents results from the study and concludes that greenhouse gas emissions increase as site slope increases; the building footprint area (as distinct from Gross Floor Area, exposes the need to reduce the area of the building to reduce greenhouse gas emissions; excavation of rock soils creates higher emissions than other soil types; and cut and fill excavation on steeply slope sites increase emissions. Potential alternative construction includes suspended floor construction systems which involve less excavation

  2. A load-displacement based approach to assess the bearing capacity and deformations of mono-bucket foundations

    DEFF Research Database (Denmark)

    Vahdatirad, Mohammadjavad; Diaz, Alberto Troya; Nielsen, Søren

    2016-01-01

    It is now accepted that a larger effort must be made in order to optimize the design so that offshore wind turbines can be competitive with the other energy resources. In this regard, mono-buckets are known as a cost-effective offshore foundation solution. In the current study, a load–displacemen......It is now accepted that a larger effort must be made in order to optimize the design so that offshore wind turbines can be competitive with the other energy resources. In this regard, mono-buckets are known as a cost-effective offshore foundation solution. In the current study, a load......–displacement based approach is introduced to assess the bearing capacity as well as the deformation of a mono-bucket foundation subjected to combined loading. A p-y curve developed for the bucket foundation is used to quantify the lateral soil response around the foundation. A numerical routine to set up the model...

  3. Cratos: A Simple Low Power Excavation and Hauling System for Lunar Oxygen Production and General Excavation Tasks

    Science.gov (United States)

    Caruso, John J.; Greer, Lawrence C.; John, Wentworth T.; Spina, Dan C.; Krasowski, Mike J.; Abel, Phillip B.; Prokop, Norman F.; Flatico, Joseph M.; Sacksteder, Kurt R.

    2007-01-01

    The development of a robust excavating and hauling system for lunar and planetary excavation is critical to the NASA mission to the Moon and Mars. Cratos was developed as a low center of gravity, small (.75m x .75m x 0.3m), low power tracked test vehicle. The vehicle was modified to excavate and haul because it demonstrated good performance capabilities in a laboratory and field testing. Tested on loose sand in the SLOPE facility, the vehicle was able to pick up, carry, and dump sand, allowing it to accomplish the standard requirements delivery of material to a lunar oxygen production site. Cratos can pick up and deliver raw material to a production plant, as well as deliver spent tailings to a disposal site. The vehicle can complete many other In-Situ Resource Utilization (ISRU) excavation chores and in conjunction with another vehicle or with additional attachments may be able to accomplish all needed ISRU tasks.

  4. The response of a high-speed train wheel to a harmonic wheel-rail force

    Science.gov (United States)

    Sheng, Xiaozhen; Liu, Yuxia; Zhou, Xin

    2016-09-01

    The maximum speed of China's high-speed trains currently is 300km/h and expected to increase to 350-400km/h. As a wheel travels along the rail at such a high speed, it is subject to a force rotating at the same speed along its periphery. This fast moving force contains not only the axle load component, but also many components of high frequencies generated from wheel-rail interactions. Rotation of the wheel also introduces centrifugal and gyroscopic effects. How the wheel responds is fundamental to many issues, including wheel-rail contact, traction, wear and noise. In this paper, by making use of its axial symmetry, a special finite element scheme is developed for responses of a train wheel subject to a vertical and harmonic wheel-rail force. This FE scheme only requires a 2D mesh over a cross-section containing the wheel axis but includes all the effects induced by wheel rotation. Nodal displacements, as a periodic function of the cross-section angle 6, can be decomposed, using Fourier series, into a number of components at different circumferential orders. The derived FE equation is solved for each circumferential order. The sum of responses at all circumferential orders gives the actual response of the wheel.

  5. Influence of polygonal wear of railway wheels on the wheel set axle stress

    Science.gov (United States)

    Wu, Xingwen; Chi, Maoru; Wu, Pingbo

    2015-11-01

    The coupled vehicle/track dynamic model with the flexible wheel set was developed to investigate the effects of polygonal wear on the dynamic stresses of the wheel set axle. In the model, the railway vehicle was modelled by the rigid multibody dynamics. The wheel set was established by the finite element method to analyse the high-frequency oscillation and dynamic stress of wheel set axle induced by the polygonal wear based on the modal stress recovery method. The slab track model was taken into account in which the rail was described by the Timoshenko beam and the three-dimensional solid finite element was employed to establish the concrete slab. Furthermore, the modal superposition method was adopted to calculate the dynamic response of the track. The wheel/rail normal forces and the tangent forces were, respectively, determined by the Hertz nonlinear contact theory and the Shen-Hedrick-Elkins model. Using the coupled vehicle/track dynamic model, the dynamic stresses of wheel set axle with consideration of the ideal polygonal wear and measured polygonal wear were investigated. The results show that the amplitude of wheel/rail normal forces and the dynamic stress of wheel set axle increase as the vehicle speeds rise. Moreover, the impact loads induced by the polygonal wear could excite the resonance of wheel set axle. In the resonance region, the amplitude of the dynamic stress for the wheel set axle would increase considerably comparing with the normal conditions.

  6. A Theoretical Framework for Managing the New Product Development Portfolio: When and How to Use Strategic Buckets

    OpenAIRE

    Raul O. Chao; Stylianos Kavadias

    2008-01-01

    Developing the "right" new products is critical to firm success and is often cited as a key competitive dimension. This paper explores new product development (NPD) portfolio strategy and the balance between incremental and radical innovation. We characterize innovative effort through a normative theoretical framework that addresses a popular practice in NPD portfolio management: the use of strategic buckets. Strategic buckets encourage the division of the overall NPD resource budget into sma...

  7. Material Composition of Bucket Foundation Transition Piece for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Nezhentseva, Anastasia; Andersen, Lars; Ibsen, Lars Bo

    2010-01-01

    In Denmark, production of renewable energy is focused on offshore wind turbines, since they make little if any inconvenience for residents in inhabited areas. High requirements are placed on the installation of the foundations which can cost about 30% of the total cost of the wind turbine....... This paper deals with the transition piece for a relatively novel type of foundation, the so-called suction bucket (caisson), focusing on the design of a transition piece connecting the turbine column with a suction bucket used as a monopod foundation for an offshore wind turbine. Since the current design...... practice is limited to the use of steel-flange-reinforced shear panels for the transition piece—a production that requires extensive welding work—a desirable solution is to find a material that provides lower cost and easier manufacturing without compromising the strength and stiffness. The paper compares...

  8. Nanoscale Tipping Bucket Effect in a Quantum Dot Transistor-Based Counter.

    Science.gov (United States)

    Hartmann, F; Maier, P; Rebello Sousa Dias, M; Göpfert, S; Castelano, L K; Emmerling, M; Schneider, C; Höfling, S; Kamp, M; Pershin, Y V; Marques, G E; Lopez-Richard, V; Worschech, L

    2017-04-12

    Electronic circuits composed of one or more elements with inherent memory, that is, memristors, memcapacitors, and meminductors, offer lower circuit complexity and enhanced functionality for certain computational tasks. Networks of these elements are proposed for novel computational paradigms that rely on information processing and storage on the same physical platform. We show a nanoscaled memdevice able to act as an electronic analogue of tipping buckets that allows reducing the dimensionality and complexity of a sensing problem by transforming it into a counting problem. The device offers a well adjustable, tunable, and reliable periodic reset that is controlled by the amounts of transferred quantum dot charges per gate voltage sweep. When subjected to periodic voltage sweeps, the quantum dot (bucket) may require up to several sweeps before a rapid full discharge occurs thus displaying period doubling, period tripling, and so on between self-governing reset operations.

  9. Heart rot hotel: fungal communities in red-cockaded woodpecker excavations

    Science.gov (United States)

    Michelle A. Jusino; Daniel L. Lindner; Mark T. Banik; Jeffrey R. Walters

    2015-01-01

    Tree-cavity excavators such as woodpeckers are ecosystem engineers that have potentially complex but poorly documented associations with wood decay fungi. Fungi facilitate cavity excavation by preparing and modifying excavation sites for cavity excavators. Associations between fungi and endangered red-cockaded woodpeckers (RCWs) are particularly interesting because...

  10. Minisatellite Attitude Guidance Using Reaction Wheels

    Directory of Open Access Journals (Sweden)

    Ion STROE

    2015-06-01

    Full Text Available In a previous paper [2], the active torques needed for the minisatellite attitude guidance from one fixed attitude posture to another fixed attitude posture were determined using an inverse dynamics method. But when considering reaction/momentum wheels, instead of this active torques computation, the purpose is to compute the angular velocities of the three reaction wheels which ensure the minisatellite to rotate from the initial to the final attitude. This paper presents this computation of reaction wheels angular velocities using a similar inverse dynamics method based on inverting Euler’s equations of motion for a rigid body with one fixed point, written in the framework of the x-y-z sequence of rotations parameterization. For the particular case A=B not equal C of an axisymmetric minisatellite, the two computations are compared: the active torques computation versus the computation of reaction wheels angular velocities ̇x , ̇y and ̇z. An interesting observation comes out from this numerical study: if the three reaction wheels are identical (with Iw the moment of inertia of one reaction wheel with respect to its central axis, then the evolutions in time of the products between Iw and the derivatives of the reaction wheels angular velocities, i.e. ̇ , ̇ and ̇ remain the same and do not depend on the moment of inertia Iw.

  11. Analysis of windlass sprocket wheel intensity

    Directory of Open Access Journals (Sweden)

    Shi Yang-yang

    2017-01-01

    Full Text Available The multi-body dynamics model of windlass was established by RecurDyn and Pro/E in this paper, and the multi-body dynamics simulation was also conducted. According to the results of the multi-body dynamics simulation, structural static analysis on sprocket wheel in dangerous conditions were executed by ANSYS Workbench. The results showed that there are three bearing situations in the meshing transmission process of sprocket wheel and chain: Single tooth bearing, two tooth bearing and carrying equal contact force and two tooth bearing but one tooth contact force reaches the maximum value. The equivalent stress value at the contact position of sprocket wheel and chain exceeds the yield stress of the chain wheel material, but it does not cause damage to chain wheel. In addition to the contact location, the equivalent stress value of the remaining parts of sprocket wheel are in the allowable stress range of sprocket wheel material, comply with the requirement of strength design.

  12. Simultaneous bicompartmental bucket-handle meniscal tears with intact anterior cruciate ligament: a case report

    Directory of Open Access Journals (Sweden)

    Beris Alexandros E

    2010-02-01

    Full Text Available Abstract Introduction Bucket handle tear of the menisci is a common type of lesion resulting from injury to the knee joint. Bucket handle injury of both menisci in almost all cases is associated with a lesion to either the anterior or the posterior cruciate ligament of the knee joint. We describe a case of acute bucket-handle tear of the medial and lateral menisci with intact anterior and posterior cruciate ligaments in a dancer. To the best of our knowledge, there are no previous reports of this type of injury in the literature. Case presentation A 28-year-old Caucasian Greek woman presented to the emergency department after sustaining an injury to her right knee during dancing. An MRI evaluation demonstrated tears in both menisci of the right knee, while the anterior and posterior cruciate ligaments were found to be intact. A partial medial and lateral meniscectomy was then performed. At a follow-up examination six months after her injury, clinical tests demonstrated that our patient's right knee was stable, had a full range of motion and had no tenderness. She was satisfied with the outcome of the operation and returned to her pre-injury activities. Conclusion We present the first case in the literature that describes a combined bucket-handle injury of both the medial and lateral menisci with an intact anterior cruciate ligament. The clinical examination of the anterior cruciate ligament was unremarkable, with no signs of deficiency or rupture. The posterior cruciate ligament was also intact. On magnetic resonance imaging, the ligaments were visualised as intact in all their length. These findings were confirmed by arthroscopic evaluation.

  13. Experimental damping assessment of a full scale offshore mono bucket foundation

    DEFF Research Database (Denmark)

    Gres, Szymon; Fejerskov, Morten; Ibsen, Lars Bo

    2016-01-01

    This paper quantifies the system damping of a offshore meteorological mast supported by a Mono Bucket foundation based on a long-term experimental campaign. The structure is located at Dogger Bank west, North Sea, and equipped with a measurement system monitoring acceleration, strain, inclination...... shows that the total damping ratio of the lowest eigenmode is normally distributed with mean value of 1.11% of critical damping. Linear correlation between the damping ratio and the significant wave height is observed....

  14. Prisen Årets studenter start-up går til Drop Bucket

    DEFF Research Database (Denmark)

    Lassen, Lisbeth

    2015-01-01

    DTU’s ny pris for årets mest innovative studerende blev ved universitetets årsfest givet til Heiða Gunnarsdóttir Nolsøe og Marie Stampe Berggreen, som står bag virksomheden Drop Bucket. Koncerndirektør for innovation og entreprenørskab, Marianne Thellersen, overakte prisen til de to innovatører s...

  15. The Bucket System – A computer mediated signaling system for group improvisation

    DEFF Research Database (Denmark)

    Dahlstedt, Palle; Nilsson, Per Anders; Robair, Gino

    2015-01-01

    The Bucket System is a new system for computer-mediated ensemble improvisation, designed by improvisers for improvisers. Coming from a tradition of structured free ensemble improvisation practices (comprovisation), influenced by post-WW2 experimental music practices, it is a signaling system...... implemented with a set of McMillen QuNeo controllers as input and output interfaces, powered by custom software. It allows for a new kind of on-stage compositional/improvisation interaction....

  16. Numerical analysis of non-stationary free surface flow in a Pelton bucket

    Energy Technology Data Exchange (ETDEWEB)

    Hana, Morten

    1999-07-01

    Computation and analysis of flow in Pelton buckets have been carried out. First a graphical method is investigated and partially improved. In order to decide whether to improve the method further or disregard it in favour of commercial computational fluid dynamics (CFD) codes, a study on numerical methods for free surface flow was carried out. This part of this work concentrates on the theoretical background for different numerical methods, and describes some practical considerations. Although small programs were created based on the literature survey, but only one reported herein, it was soon found that commonly available numerical codes were favourable in use. A code, RIPPLE, was acquired to study the Volume of Fluid (VOF) method in detail. The commercial codes used were Flow-3D and CFX-4. These programs were used in three different cases. First, a simplified 2-dimensional case was verified experimentally. Next, a 3-dimensional fixed jet calculation was carried out. Finally, numerical calculations with relative motion between the jet and buckets were carried out with CFX-4. The conclusion is that commercial CFD codes can replace the graphical method. But careful implementation is needed in order to resolve the special features of Pelton turbines, which are the free surface, the complex geometry and the relative motion between the jet and the bucket.

  17. Erosion of Pelton buckets and changes in turbine efficiency measured in the HPP Fieschertal

    Science.gov (United States)

    Abgottspon, A.; Staubli, T.; Felix, D.

    2016-11-01

    Geometrical changes and material loss of Pelton turbine runners as well as changes in turbine efficiency were measured at HPP Fieschertal in Valais, Switzerland. The HPP is equipped with two horizontal axis Pelton units, with each 32 MW nominal power, 7.5 m3/s design discharge, 515 m head and two injectors. The injectors and the buckets are hard-coated. Hydro-abrasive erosion was quantified based on repeated measurements on two runner buckets using (i) 3d-scanning and (ii) a coating thickness gauge. Changes in efficiency were measured by applying the sliding needle procedure. In addition to these periodically performed measurements, efficiency was also continuously monitored. The highest erosion rate was measured during the first half of the sediment season 2012 including a major sediment transport event. Because the runner was not fully reconditioned at the beginning of this season, progressive damages occurred. After the event, a splitter width of 10 mm was measured, corresponding to 1.5 % of the inner bucket width. The cut-outs were eroded by up to 9 mm towards the axis. The efficiency reductions ranged from 1 % in the year with the major sediment transport event to insignificant differences in 2014, when the sediment load was small and only little hydro-abrasive erosion occurred.

  18. Bucket and straw technique to facilitate passage of a ventriculoperitoneal shunt through the distal tunneling sheath.

    Science.gov (United States)

    Downes, Angela E; Vandergrift, William A; Beckman, Joshua M; Truong, Devon; Tuite, Gerald F

    2014-12-01

    Placement of a ventriculoperitoneal shunt (VPS) is a procedure comprising many small steps. Difficulties and delays can arise when passing the distal shunt tubing down the distal tunneling sheath during surgery. The authors of this report describe a simple technique for quickly passing the distal catheter of a VPS through the tunneler sheath, whereby the sheath is used as a fluid tube to allow the distal catheter to be drawn through the fluid tube under suction pressure. The plastic sheath that surrounds the shunt tunneler device is used as a fluid tube, or "straw," with the proximal aperture submerged into a bucket of sterile irrigation liquid containing the distal catheter. Suction pressure is placed against the distal aperture of the tunneler, and the shunt catheter is quickly drawn through the sheath. No special equipment is required. In time trials, the bucket and straw technique took an average of 0.43 seconds, whereas traditional passage methods took 32.3 seconds. The "bucket and straw" method for passing distal shunt tubing through the tunneler sheath is a technique that increases surgical efficiency and reduces manual contact with shunt hardware.

  19. COMBINED INSIDE-OUT AND ALL-INSIDE TECHNIQUE IN BUCKET-HANDLE MENISCUS TEARS.

    Science.gov (United States)

    Yılmaz, Serdar; Cankaya, Deniz; Fırat, Ahmet; Devecı, Alper; Ozkurt, Bulent; Bozkurt, Murat

    2016-01-01

    To determine the outcomes after combined inside-out and all-inside repair technique of bucket-handle meniscus tears. A retrospective review was made of patients with bucket-handle meniscus tears repaired with combined techniques, using the all-inside technique in posterior meniscal tears and the inside-out technique in the middle part of the meniscal tears. Meniscal healing was assessed clinically using Barrett's criteria and MRI. The study comprised 52 patients with a mean age of 28.4 years old (range, 19-52 years old). The mean follow-up period was 31.3 months (range, 24-59 months). Two patients had ACL re-rupture, and complete meniscal healing was achieved in all but one patient. Although improved from preoperative status, Tegner and Lysholm scores were lower in the ACL reconstructed patients than in the intact ACL patients. Combined inside-out and all-inside meniscal repair technique is a successful and cost-effective treatment method in bucket-handle meniscus tears. Level of Evidence IV, Therapeutic Study.

  20. Subjective visual vertical with the bucket method in Brazilian healthy individuals.

    Science.gov (United States)

    Ferreira, Maristela Mian; Cunha, Fabiana; Ganança, Cristina Freitas; Ganança, Maurício Malavasi; Caovilla, Heloisa Helena

    2016-01-01

    The capacity of a healthy individual to estimate the true vertical in relation to the Earth when a fluorescent line is aligned in a completely dark room is called the subjective visual vertical. To evaluate subjective visual vertical using the bucket method in healthy Brazilian individuals. Binocular subjective visual vertical was measured in 100 healthy volunteers, 50 females and 50 males. The volunteers indicated the estimated position in which a fluorescent line inside a bucket reached the vertical position. A total of ten repetitions were performed, five clockwise and five counterclockwise. Data were tabulated and analyzed statistically. It was observed that the highest concentration of absolute values of vertical deviation was present up to 3°, regardless of gender, and the vertical deviation did not increase with age. The analysis of the mean of the absolute values of deviations from the vertical of 90% of the sample showed a maximum value of 2.6°, and at the analysis of 95%, the maximum value was 3.4° deviation from the vertical. The bucket method is easy to perform and interpret when assessing the deviation of the subjective visual vertical in relation to the true vertical in healthy Brazilian individuals. Copyright © 2016 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  1. Design and Development of Electro-Mechanical Twins Tipping Buckets Runoff-Meter

    Directory of Open Access Journals (Sweden)

    Olotu Yahaya

    2014-07-01

    Full Text Available Electro-mechanical tipping bucket runoff-meter was designed and developed to measure surface runoff water using locally-sourced components. The instrument consists of metallic-fabricated runoff plot area of 2 m 2 , depth 0.25 m and metal gauge of 3mm. The tipping operation was initiated by arranging the sensitive electro-mechanical components such digital micro-switch (SW1,SW2, SW3 and SW4, pair of open/close circuit breakers (No,Nc, electronic speed gear and circular rotating disc to a pair of twins buckets of runoff volume 0.141 liter capacity per bucket which corresponds to 0.25 mm runoff depth. The whole arrangement was powered by a 12V by 75 AH battery and the tipping processes was being recorded by the electro-mechanical data logger. The instrument has a measuring accuracy of ±0.001 liter per tip. It was calibrated to measure minimum and maximum runoff volume from 0.14l to 200 liters, these values correspond to 0.25 mm and 800 mm runoff depths respectively. Therefore, precise results obtained using the instrument could be used to establish strong database for measuring and storing accurate surface runoff data which in turn could be applied for hydrological modeling for sustainable water resources management and design of hydraulic structures

  2. 49 CFR 393.209 - Steering wheel systems.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Steering wheel systems. 393.209 Section 393.209... NECESSARY FOR SAFE OPERATION Frames, Cab and Body Components, Wheels, Steering, and Suspension Systems § 393.209 Steering wheel systems. (a) The steering wheel shall be secured and must not have any spokes...

  3. Improving of operating ability of wheels and rail tracks

    Directory of Open Access Journals (Sweden)

    George TUMANISHVILI

    2014-09-01

    Full Text Available The high cost of wheels and rails due to wear and rolling contact fatigue is one of the main problems in the railway transport. The values of creepage, sliding distance and wear rate of wheels and rails at rolling of a wheel on the rail greatly depend on geometric characteristics of working profiles of wheels and rails and location of wheels relative to rails. In the present work the functional requirements of various parts of profiles of wheels and rails and dominating kinds of their damage in various operating conditions are considered and a new profile of a wheel and device for fastening of rails are offered.

  4. Impact and modal analysis for different alloy wheel compositions

    Science.gov (United States)

    Suman, Shwetabh; Abhimanyu Abrol, J.; Ravi, K.

    2017-11-01

    Wheels are an important component in the vehicle. The strength of the Alloy wheel rim is an important property of the Alloy wheel, which plays an important part in determining the overall performance of the vehicle, the structural integrity of the rim and the life of the Alloy wheel rim. With the advent of new Alloy wheel materials, new options are available to replace the conventional Aluminium Alloy wheels with new ones. The new Alloy wheel rim material and design need to be tested virtually for optimizing the appropriate design and material and the optimised wheel in virtual mode can be tested experimentally for the performance in real-time conditions before they can be used in the vehicles. The work in this project includes doing the impact and modal analysis for different alloy wheel compositions. From the results obtained, the optimum alloy wheel is suggested, which can be considered with further experimental validation.

  5. The Influence of Wheel/Rail Contact Conditions on the Microstructure and Hardness of Railway Wheels

    Science.gov (United States)

    Davis, Claire

    2014-01-01

    The susceptibility of railway wheels to wear and rolling contact fatigue damage is influenced by the properties of the wheel material. These are influenced by the steel composition, wheel manufacturing process, and thermal and mechanical loading during operation. The in-service properties therefore vary with depth below the surface and with position across the wheel tread. This paper discusses the stress history at the wheel/rail contact (derived from dynamic simulations) and observed variations in hardness and microstructure. It is shown that the hardness of an “in-service” wheel rim varies significantly, with three distinct effects. The underlying hardness trend with depth can be related to microstructural changes during manufacturing (proeutectoid ferrite fraction and pearlite lamellae spacing). The near-surface layer exhibits plastic flow and microstructural shear, especially in regions which experience high tangential forces when curving, with consequentially higher hardness values. Between 1 mm and 7 mm depth, the wheel/rail contacts cause stresses exceeding the material yield stress, leading to work hardening, without a macroscopic change in microstructure. These changes in material properties through the depth of the wheel rim would tend to increase the likelihood of crack initiation on wheels toward the end of their life. This correlates with observations from several train fleets. PMID:24526883

  6. The influence of wheel/rail contact conditions on the microstructure and hardness of railway wheels.

    Science.gov (United States)

    Molyneux-Berry, Paul; Davis, Claire; Bevan, Adam

    2014-01-01

    The susceptibility of railway wheels to wear and rolling contact fatigue damage is influenced by the properties of the wheel material. These are influenced by the steel composition, wheel manufacturing process, and thermal and mechanical loading during operation. The in-service properties therefore vary with depth below the surface and with position across the wheel tread. This paper discusses the stress history at the wheel/rail contact (derived from dynamic simulations) and observed variations in hardness and microstructure. It is shown that the hardness of an "in-service" wheel rim varies significantly, with three distinct effects. The underlying hardness trend with depth can be related to microstructural changes during manufacturing (proeutectoid ferrite fraction and pearlite lamellae spacing). The near-surface layer exhibits plastic flow and microstructural shear, especially in regions which experience high tangential forces when curving, with consequentially higher hardness values. Between 1 mm and 7 mm depth, the wheel/rail contacts cause stresses exceeding the material yield stress, leading to work hardening, without a macroscopic change in microstructure. These changes in material properties through the depth of the wheel rim would tend to increase the likelihood of crack initiation on wheels toward the end of their life. This correlates with observations from several train fleets.

  7. The Influence of Wheel/Rail Contact Conditions on the Microstructure and Hardness of Railway Wheels

    Directory of Open Access Journals (Sweden)

    Paul Molyneux-Berry

    2014-01-01

    Full Text Available The susceptibility of railway wheels to wear and rolling contact fatigue damage is influenced by the properties of the wheel material. These are influenced by the steel composition, wheel manufacturing process, and thermal and mechanical loading during operation. The in-service properties therefore vary with depth below the surface and with position across the wheel tread. This paper discusses the stress history at the wheel/rail contact (derived from dynamic simulations and observed variations in hardness and microstructure. It is shown that the hardness of an “in-service” wheel rim varies significantly, with three distinct effects. The underlying hardness trend with depth can be related to microstructural changes during manufacturing (proeutectoid ferrite fraction and pearlite lamellae spacing. The near-surface layer exhibits plastic flow and microstructural shear, especially in regions which experience high tangential forces when curving, with consequentially higher hardness values. Between 1 mm and 7 mm depth, the wheel/rail contacts cause stresses exceeding the material yield stress, leading to work hardening, without a macroscopic change in microstructure. These changes in material properties through the depth of the wheel rim would tend to increase the likelihood of crack initiation on wheels toward the end of their life. This correlates with observations from several train fleets.

  8. The use of knowledge-based Genetic Algorithm for starting time optimisation in a lot-bucket MRP

    Science.gov (United States)

    Ridwan, Muhammad; Purnomo, Andi

    2016-01-01

    In production planning, Material Requirement Planning (MRP) is usually developed based on time-bucket system, a period in the MRP is representing the time and usually weekly. MRP has been successfully implemented in Make To Stock (MTS) manufacturing, where production activity must be started before customer demand is received. However, to be implemented successfully in Make To Order (MTO) manufacturing, a modification is required on the conventional MRP in order to make it in line with the real situation. In MTO manufacturing, delivery schedule to the customers is defined strictly and must be fulfilled in order to increase customer satisfaction. On the other hand, company prefers to keep constant number of workers, hence production lot size should be constant as well. Since a bucket in conventional MRP system is representing time and usually weekly, hence, strict delivery schedule could not be accommodated. Fortunately, there is a modified time-bucket MRP system, called as lot-bucket MRP system that proposed by Casimir in 1999. In the lot-bucket MRP system, a bucket is representing a lot, and the lot size is preferably constant. The time to finish every lot could be varying depends on due date of lot. Starting time of a lot must be determined so that every lot has reasonable production time. So far there is no formal method to determine optimum starting time in the lot-bucket MRP system. Trial and error process usually used for it but some time, it causes several lots have very short production time and the lot-bucket MRP would be infeasible to be executed. This paper presents the use of Genetic Algorithm (GA) for optimisation of starting time in a lot-bucket MRP system. Even though GA is well known as powerful searching algorithm, however, improvement is still required in order to increase possibility of GA in finding optimum solution in shorter time. A knowledge-based system has been embedded in the proposed GA as the improvement effort, and it is proven that the

  9. Magnetic Levitation Experiments with the Electrodynamic Wheel

    Science.gov (United States)

    Cordrey, Vincent; Gutarra-Leon, Angel; Gaul, Nathan; Majewski, Walerian

    Our experiments explored inductive magnetic levitation using circular Halbach arrays with the strong variable magnetic field on the outer rim of the ring. Such a system is usually called an Electrodynamic Wheel (EDW). Rotating this wheel around a horizontal axis above a flat conducting surface should induce eddy currents in said surface through the variable magnetic flux. The eddy currents produce, in turn, their own magnetic fields which interact with the magnets of the EDW. We constructed two Electrodynamic Wheels with different diameters and demonstrated that the magnetic interactions produce both lift and drag forces on the EDW which can be used for levitation and propulsion of the EDW. The focus of our experiments is the direct measurement of lift and drag forces to compare with theoretical models using wheels of two different radii. Supported by Grants from the Virginia Academy of Science, Society of Physics Students, Virginia Community College System, and the NVCC Educational Foundation.

  10. UT Biomedical Informatics Lab (BMIL) Probability Wheel.

    Science.gov (United States)

    Huang, Sheng-Cheng; Lee, Sara; Wang, Allen; Cantor, Scott B; Sun, Clement; Fan, Kaili; Reece, Gregory P; Kim, Min Soon; Markey, Mia K

    2016-01-01

    A probability wheel app is intended to facilitate communication between two people, an "investigator" and a "participant," about uncertainties inherent in decision-making. Traditionally, a probability wheel is a mechanical prop with two colored slices. A user adjusts the sizes of the slices to indicate the relative value of the probabilities assigned to them. A probability wheel can improve the adjustment process and attenuate the effect of anchoring bias when it is used to estimate or communicate probabilities of outcomes. The goal of this work was to develop a mobile application of the probability wheel that is portable, easily available, and more versatile. We provide a motivating example from medical decision-making, but the tool is widely applicable for researchers in the decision sciences.

  11. Reaction Wheel with Embedded MEMS IMU Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Reaction wheels are used to stabilize satellites and to slew their orientation from object to object with precision and accuracy by varying the rotational speed of...

  12. Reaction Wheel Disturbance Model Extraction Software Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Reaction wheel mechanical noise is one of the largest sources of disturbance forcing on space-based observatories. Such noise arises from mass imbalance, bearing...

  13. ANALYSIS OF FORMING TREAD WHEEL SETS

    Directory of Open Access Journals (Sweden)

    Igor IVANOV

    2017-09-01

    Full Text Available This paper shows the results of a theoretical study of profile high-speed grinding (PHSG for forming tread wheel sets during repair instead of turning and mold-milling. Significant disadvantages of these methods are low capacity to adapt to the tool and inhomogeneous structure of the wheel material. This leads to understated treatment regimens and difficulties in recovering wheel sets with thermal and mechanical defects. This study carried out modeling and analysis of emerging cutting forces. Proposed algorithms describe the random occurrence of the components of the cutting forces in the restoration profile of wheel sets with an inhomogeneous structure of the material. To identify the statistical features of randomly generated structures fractal dimension and the method of random additions were used. The multifractal spectrum formed is decomposed into monofractals by wavelet transform. The proposed method allows you to create the preconditions for controlling the parameters of the treatment process.

  14. Collective workload organization in confined excavation of granular media

    Science.gov (United States)

    Monaenkova, Daria; Linevich, Vadim; Goodisman, Michael A.; Goldman, Daniel I.

    2015-03-01

    Many social insects collectively construct large nests in complex substrates; such structures are often composed of narrow tunnels. The benefits of collective construction, including reduced construction costs per worker come with challenges of navigation in crowded, confined spaces. Here we study the workforce organization of groups of S. invicta fire ants creating tunnels in wet granular media. We monitor the activity levels of marked (painted) workers-defined as a number of tunnel visits over 12 hours- during initiation of tunnels. The activity levels are described by a Lorenz curve with a Gini coefficient of ~ 0 . 7 indicating that a majority of the excavation is performed by a minority of workers. We hypothesize that this workload distribution is beneficial for excavation in crowded conditions, and use a 2D cellular automata (CA) model to reproduce behaviors of the excavating ants. CA simulations reveal that tunnel construction rates decrease in groups of equally active animals compared to groups with the natural workload distribution. We use predictions of the CA model to organize collective excavation of granular material by teams of digging robots, and use the robots to test hypotheses of crowded excavation in the physical world. We acknowledge support of National Science Foundation, Physics of Living Systems division.

  15. Radiopaque Tagging Masks Caries Lesions following Incomplete Excavation in vitro.

    Science.gov (United States)

    Schwendicke, F; Meyer-Lueckel, H; Schulz, M; Dörfer, C E; Paris, S

    2014-06-01

    One-step incomplete excavation seals caries-affected dentin under a restoration and appears to be advantageous in the treatment of deep lesions. However, it is impossible to discriminate radiographically between intentionally left, arrested lesions and overlooked or active lesions. This diagnostic uncertainty decreases the acceptance of minimally invasive excavation and might lead to unnecessary re-treatment of incompletely excavated teeth. Radiopaque tagging of sealed lesions might mask arrested lesions and assist in discrimination from progressing lesions. Therefore, we microradiographically screened 4 substances (SnCl2, AgNO3, CsF, CsCH3COO) for their effect on artificial lesions. Since water-dissolved tin chloride (SnCl2×Aq) was found to stably mask artificial lesions, we then investigated its radiographic effects on progressing lesions. Natural lesions were incompletely excavated and radiopaque tagging performed. Grey-value differences (△GV) between sound and carious dentin were determined and radiographs assessed by 20 dentists. While radiographic effects of SnCl2×Aq were stable for non-progressing lesions, they significantly decreased during a second demineralization (p excavation. © International & American Associations for Dental Research.

  16. A Nontoxic Barlow's Wheel

    Science.gov (United States)

    Daffron, John A.; Greenslade, Thomas B., Jr.

    2015-01-01

    Barlow's wheel has been a favorite demonstration since its invention by Peter Barlow (1776-1862) in 1822. In the form shown in Fig. 1, it represents the first electric motor. The interaction between the electric current passing from the axle of the wheel to the rim and the magnetic field produced by the U-magnet produces a torque that turns…

  17. Aerodynamic analysis of an isolated vehicle wheel

    Science.gov (United States)

    Leśniewicz, P.; Kulak, M.; Karczewski, M.

    2014-08-01

    Increasing fuel prices force the manufacturers to look into all aspects of car aerodynamics including wheels, tyres and rims in order to minimize their drag. By diminishing the aerodynamic drag of vehicle the fuel consumption will decrease, while driving safety and comfort will improve. In order to properly illustrate the impact of a rotating wheel aerodynamics on the car body, precise analysis of an isolated wheel should be performed beforehand. In order to represent wheel rotation in contact with the ground, presented CFD simulations included Moving Wall boundary as well as Multiple Reference Frame should be performed. Sliding mesh approach is favoured but too costly at the moment. Global and local flow quantities obtained during simulations were compared to an experiment in order to assess the validity of the numerical model. Results of investigation illustrates dependency between type of simulation and coefficients (drag and lift). MRF approach proved to be a better solution giving result closer to experiment. Investigation of the model with contact area between the wheel and the ground helps to illustrate the impact of rotating wheel aerodynamics on the car body.

  18. A novel energy recovery system for parallel hybrid hydraulic excavator.

    Science.gov (United States)

    Li, Wei; Cao, Baoyu; Zhu, Zhencai; Chen, Guoan

    2014-01-01

    Hydraulic excavator energy saving is important to relieve source shortage and protect environment. This paper mainly discusses the energy saving for the hybrid hydraulic excavator. By analyzing the excess energy of three hydraulic cylinders in the conventional hydraulic excavator, a new boom potential energy recovery system is proposed. The mathematical models of the main components including boom cylinder, hydraulic motor, and hydraulic accumulator are built. The natural frequency of the proposed energy recovery system is calculated based on the mathematical models. Meanwhile, the simulation models of the proposed system and a conventional energy recovery system are built by AMESim software. The results show that the proposed system is more effective than the conventional energy saving system. At last, the main components of the proposed energy recovery system including accumulator and hydraulic motor are analyzed for improving the energy recovery efficiency. The measures to improve the energy recovery efficiency of the proposed system are presented.

  19. A Novel Energy Recovery System for Parallel Hybrid Hydraulic Excavator

    Directory of Open Access Journals (Sweden)

    Wei Li

    2014-01-01

    Full Text Available Hydraulic excavator energy saving is important to relieve source shortage and protect environment. This paper mainly discusses the energy saving for the hybrid hydraulic excavator. By analyzing the excess energy of three hydraulic cylinders in the conventional hydraulic excavator, a new boom potential energy recovery system is proposed. The mathematical models of the main components including boom cylinder, hydraulic motor, and hydraulic accumulator are built. The natural frequency of the proposed energy recovery system is calculated based on the mathematical models. Meanwhile, the simulation models of the proposed system and a conventional energy recovery system are built by AMESim software. The results show that the proposed system is more effective than the conventional energy saving system. At last, the main components of the proposed energy recovery system including accumulator and hydraulic motor are analyzed for improving the energy recovery efficiency. The measures to improve the energy recovery efficiency of the proposed system are presented.

  20. Excavation Equipment Recognition Based on Novel Acoustic Statistical Features.

    Science.gov (United States)

    Cao, Jiuwen; Wang, Wei; Wang, Jianzhong; Wang, Ruirong

    2017-12-01

    Excavation equipment recognition attracts increasing attentions in recent years due to its significance in underground pipeline network protection and civil construction management. In this paper, a novel classification algorithm based on acoustics processing is proposed for four representative excavation equipments. New acoustic statistical features, namely, the short frame energy ratio, concentration of spectrum amplitude ratio, truncated energy range, and interval of pulse are first developed to characterize acoustic signals. Then, probability density distributions of these acoustic features are analyzed and a novel classifier is presented. Experiments on real recorded acoustics of the four excavation devices are conducted to demonstrate the effectiveness of the proposed algorithm. Comparisons with two popular machine learning methods, support vector machine and extreme learning machine, combined with the popular linear prediction cepstral coefficients are provided to show the generalization capability of our method. A real surveillance system using our algorithm is developed and installed in a metro construction site for real-time recognition performance validation.

  1. Development of Force Reflecting Joystick for Hydraulic Excavator

    Science.gov (United States)

    Ahn, Kyoungkwan

    In teleoperation field robotic system such as hydraulically actuated robotic excavator, the maneuverability and convenience is the most important in the operation of robotic excavator. Particularly the force information is important in dealing with digging and leveling operation in the teleoperated excavator. This paper presents a new force reflecting joystick in a velocity-force type bilateral teleoperation system. The master system is electrical joystick and the slave system is hydraulic cylinder. Particularly pneumatic motor is used newly in the master joystick for force reflection and the information of the pressure of slave cylinder is measured and utilized as force feedback signal. This paper also proposes a novel force-reflection gain selecting algorithm based on artificial neural network. Finally a series of experiments are conducted under various load conditions using a laboratory-made one axis slave cylinder and load simulator.

  2. High frequency vibration characteristics of electric wheel system under in-wheel motor torque ripple

    Science.gov (United States)

    Mao, Yu; Zuo, Shuguang; Wu, Xudong; Duan, Xianglei

    2017-07-01

    With the introduction of in-wheel motor, the electric wheel system encounters new vibration problems brought by motor torque ripple excitation. In order to analyze new vibration characteristics of electric wheel system, torque ripple of in-wheel motor based on motor module and vector control system is primarily analyzed, and frequency/order features of the torque ripple are discussed. Then quarter vehicle-electric wheel system (QV-EWS) dynamics model based on the rigid ring tire assumption is established and the main parameters of the model are identified according to tire free modal test. Modal characteristics of the model are further analyzed. The analysis indicates that torque excitation of in-wheel motor is prone to arouse horizontal vibration, in which in-phase rotational, anti-phase rotational and horizontal translational modes of electric wheel system mainly participate. Based on the model, vibration responses of the QV-EWS under torque ripple are simulated. The results show that unlike vertical low frequency (lower than 20 Hz) vibration excited by road roughness, broadband torque ripple will arouse horizontal high frequency (50-100 Hz) vibration of electric wheel system due to participation of the three aforementioned modes. To verify the theoretical analysis, the bench experiment of electric wheel system is conducted and vibration responses are acquired. The experiment demonstrates the high frequency vibration phenomenon of electric wheel system and the measured order features as well as main resonant frequencies agree with simulation results. Through theoretical modeling, analysis and experiments this paper reveals and explains the high frequency vibration characteristics of electric wheel system, providing references for the dynamic analysis, optimal design of QV-EWS.

  3. Support system, excavation arrangement, and process of supporting an object

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, Bill W.

    2017-08-01

    A support system, an excavation arrangement, and a process of supporting an object are disclosed. The support system includes a weight-bearing device and a camming mechanism positioned below the weight-bearing device. A downward force on the weight-bearing device at least partially secures the camming mechanism to opposing surfaces. The excavation arrangement includes a borehole, a support system positioned within and secured to the borehole, and an object positioned on and supported by the support system. The process includes positioning and securing the support system and positioning the object on the weight-bearing device.

  4. Asteroid Icy Regolith Excavation and Volatile Capture Project

    Science.gov (United States)

    Zeitlin, Nancy; Mantovani, James; Swanger, Adam; Townsend, Ivan

    2015-01-01

    Icy regolith simulants will be produced in a relevant vacuum environment using various minerals, including hydrated minerals, that are found in C-type meteorites and in other types of planetary regolith. This will allow us to characterize the mechanical strength of the icy regolith as a function of ice content using penetration, excavation, and sample capture devices. The results of this study will benefit engineers in designing efficient regolith excavators and ISRU processing systems for future exploration missions to asteroids and other planetary bodies.

  5. Rock Properties Determined Continuously from TBM Excavation Process

    Directory of Open Access Journals (Sweden)

    Edita Lazarová

    2004-12-01

    Full Text Available The computer monitoring system used at excavation of exploratory galleries of motorway tunnels Branisko and Višòové-Dubná skala (excavated by Wirth TB-II-330H/M and Voest Alpine ATB 35H, respectively brought an ample study material. Several characteristics of rock environment in the line of exploratory galleries were determined using developed mathematical models. The verification of the models was carried out based on the comparison of results of mathematical models with results of common procedures of detailed engineering-geological investigation. The description of the continuous method and the results of comparisons are subject of this paper.

  6. Model Predictive Control considering Reachable Range of Wheels for Leg / Wheel Mobile Robots

    Science.gov (United States)

    Suzuki, Naito; Nonaka, Kenichiro; Sekiguchi, Kazuma

    2016-09-01

    Obstacle avoidance is one of the important tasks for mobile robots. In this paper, we study obstacle avoidance control for mobile robots equipped with four legs comprised of three DoF SCARA leg/wheel mechanism, which enables the robot to change its shape adapting to environments. Our previous method achieves obstacle avoidance by model predictive control (MPC) considering obstacle size and lateral wheel positions. However, this method does not ensure existence of joint angles which achieves reference wheel positions calculated by MPC. In this study, we propose a model predictive control considering reachable mobile ranges of wheels positions by combining multiple linear constraints, where each reachable mobile range is approximated as a convex trapezoid. Thus, we achieve to formulate a MPC as a quadratic problem with linear constraints for nonlinear problem of longitudinal and lateral wheel position control. By optimization of MPC, the reference wheel positions are calculated, while each joint angle is determined by inverse kinematics. Considering reachable mobile ranges explicitly, the optimal joint angles are calculated, which enables wheels to reach the reference wheel positions. We verify its advantages by comparing the proposed method with the previous method through numerical simulations.

  7. The Goal Wheel: Adapting Navajo Philosophy and the Medicine Wheel to Work with Adolescents

    Science.gov (United States)

    Garner, Holly; Bruce, Mary Alice; Stellern, John

    2011-01-01

    The purpose of this article is to describe a group counseling model that is based on the indigenous medicine wheel as well as Navajo philosophy by which to help troubled adolescents restore harmony and balance in their lives, through establishing goals and sequential steps to accomplish these goals. The authors call this model the Goal Wheel. A…

  8. Wheel running, food intake, and body weight in male rats.

    Science.gov (United States)

    Looy, H; Eikelboom, R

    1989-02-01

    The acquisition of wheel running, its effects on food intake and body weight, and the effects of wheel deprivation, were examined in male rats. Running increased during the first 15 days of access, then plateaued. When wheels were unlocked after 10 days of deprivation, running was reduced, but quickly recovered to original levels. Animals first given wheel access 49 days into the study ran little, with no increase over days. Food intake dropped each time with wheel access, but recovered to control levels over 10-14 days. Wheel deprivation resulted in a temporary hyperphagia. With wheel access, weight initially dropped and was then maintained at a reduced percentage of homecage-housed animals. In male rats wheel access appears to have temporary effects on food intake, and long term effects on weight. Marked differences in the activity of same-age rats suggest that wheel running is in part a function of housing history.

  9. Project considerations and design of systems for wheeling cogenerated power

    Energy Technology Data Exchange (ETDEWEB)

    Tessmer, R.G. Jr.; Boyle, J.R.; Fish, J.H. III; Martin, W.A.

    1994-08-01

    Wheeling electric power, the transmission of electricity not owned by an electric utility over its transmission lines, is a term not generally recognized outside the electric utility industry. Investigation of the term`s origin is intriguing. For centuries, wheel has been used to describe an entire machine, not just individual wheels within a machine. Thus we have waterwheel, spinning wheel, potter`s wheel and, for an automobile, wheels. Wheel as a verb connotes transmission or modification of forces and motion in machinery. With the advent of an understanding of electricity, use of the word wheel was extended to be transmission of electric power as well as mechanical power. Today, use of the term wheeling electric power is restricted to utility transmission of power that it doesn`t own. Cogeneration refers to simultaneous production of electric and thermal power from an energy source. This is more efficient than separate production of electricity and thermal power and, in many instances, less expensive.

  10. Design of Wheeled Mobile Robot with Tri-Star Wheel as Rescue Robot

    Directory of Open Access Journals (Sweden)

    Rafiuddin Syam

    2016-05-01

    Full Text Available This study aims to design, and analyze a mobilerobot that can handle some of the obstacles, they are unevensurfaces, slopes, can also climb stairs. WMR in this study is Tristarwheel that is containing three wheels for each set. Onaverage surface only two wheels in contact with the surface, ifthere is an uneven surface or obstacle then the third wheel willrotate with the rotation center of the wheel in contact with theleading obstacle then only one wheel in contact with the surface.This study uses the C language program. Furthermore, theminimum thrust to be generated torque of the motor andtransmission is 9.56 kg. The results obtained by calculation andanalysis of DC motors used must have a torque greater than14.67 kg.cm. Minimum thrust to be generated motor torque andthe transmission is 9.56 kg. The experimental results give goodresults for robot to moving forward, backward, turn left, turnright and climbing the stairs

  11. Investigations on macro-element modelling of bucket foundations for offshore wind turbines

    DEFF Research Database (Denmark)

    Foglia, Aligi; Govoni, Laura; Gottardi, Guido

    In this report a macro-element model for bucket foundations is formulated and validated against small-scale experimental results. The topics investigated are the response of the foundation under general monotonic loading and the long-term accumulated displacements under cyclic loading. The macro......-model for shallow foundations proposed by Nova and Montrasio (1991) is modified to comply with the response of skirted foundations for offshore wind turbines under general loading. On the base of di Prisco et al. (2003a), the constitutive relationship is modified to account for cyclic loading. The validation...

  12. Cooling supply system for stage 3 bucket of a gas turbine

    Science.gov (United States)

    Eldrid, Sacheverel Quentin; Burns, James Lee; Palmer, Gene David; Leone, Sal Albert; Drlik, Gary Joseph; Gibler, Edward Eugene

    2002-01-01

    In a land based gas turbine including a compressor, a combustor and turbine section including at least three stages, an improvement comprising an inlet into a third stage nozzle from the compressor for feeding cooling air from the compressor to the third stage nozzle; at least one passageway running substantially radially through each airfoil of the third stage nozzle and an associated diaphragm, into an annular space between the rotor and the diaphragm; and passageways communicating between the annular space and individual buckets of the third stage.

  13. Quicksort, largest bucket, and min-wise hashing with limited independence

    DEFF Research Database (Denmark)

    Knudsen, Mathias Bæk Tejs; Stöckel, Morten

    2015-01-01

    to be k-independent if every variable is uniform and every size k subset is independent. In this paper we consider three classic algorithms under limited independence. Besides the theoretical interest in removing the unrealistic assumption of full independence, the work is motivated by lower independence...... being more practical. We provide new bounds for randomized quicksort, min-wise hashing and largest bucket size under limited independence. Our results can be summarized as follows. Randomized Quicksort. When pivot elements are computed using a 5-independent hash function, Karloff and Raghavan, J.ACM’93...

  14. Small-Scale Testing of Laterally Loaded Bucket Foundations in Dense Sand

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Foglia, Aligi

    Monopod bucket foundations promise to become a reliable and cost-effective concept for offshore wind turbine. Physical models are essential to understand the behavior of soil-structure systems. When conducting small-scale experiments on soil, scale effects can considerably affect the tests outcome....... In a bid for overcoming this issue, a novel testing system based on the application of suction between the soil surface and a membrane is employed. The comparison between the tests conducted at stress levels of 0 kPa, and the tests with increased stress level, shows remarkable differences. In particular...

  15. Reaction Wheel Disturbance Model Extraction Software - RWDMES

    Science.gov (United States)

    Blaurock, Carl

    2009-01-01

    The RWDMES is a tool for modeling the disturbances imparted on spacecraft by spinning reaction wheels. Reaction wheels are usually the largest disturbance source on a precision pointing spacecraft, and can be the dominating source of pointing error. Accurate knowledge of the disturbance environment is critical to accurate prediction of the pointing performance. In the past, it has been difficult to extract an accurate wheel disturbance model since the forcing mechanisms are difficult to model physically, and the forcing amplitudes are filtered by the dynamics of the reaction wheel. RWDMES captures the wheel-induced disturbances using a hybrid physical/empirical model that is extracted directly from measured forcing data. The empirical models capture the tonal forces that occur at harmonics of the spin rate, and the broadband forces that arise from random effects. The empirical forcing functions are filtered by a physical model of the wheel structure that includes spin-rate-dependent moments (gyroscopic terms). The resulting hybrid model creates a highly accurate prediction of wheel-induced forces. It accounts for variation in disturbance frequency, as well as the shifts in structural amplification by the whirl modes, as the spin rate changes. This software provides a point-and-click environment for producing accurate models with minimal user effort. Where conventional approaches may take weeks to produce a model of variable quality, RWDMES can create a demonstrably high accuracy model in two hours. The software consists of a graphical user interface (GUI) that enables the user to specify all analysis parameters, to evaluate analysis results and to iteratively refine the model. Underlying algorithms automatically extract disturbance harmonics, initialize and tune harmonic models, and initialize and tune broadband noise models. The component steps are described in the RWDMES user s guide and include: converting time domain data to waterfall PSDs (power spectral

  16. Detecting defects in diaphragm walls prior to excavation

    NARCIS (Netherlands)

    Spruit, R.; Hopman, V.; Van Tol, A.F.; Broere, W.

    2011-01-01

    Recent incidents with leaking diaphragm walls during construction of subway lines in Amsterdam and Rotterdam (Netherlands) have led to reconsideration of the diaphragm wall as a retaining wall construction for deep excavations. In our opinion the joints between the panels are the weak spot. During

  17. Choroidal excavation with polypoidal choroidal vasculopathy: a case report.

    Science.gov (United States)

    Kobayashi, Wataru; Abe, Toshiaki; Tamai, Hiroshi; Nakazawa, Toru

    2012-01-01

    This is a report of a case of choroidal excavation accompanied by polypoidal choroidal vasculopathy (PCV) and retinal pigment epithelium detachment (PED). A 57-year-old Japanese woman who had begun complaining of metamorphopsia in her left eye 7 months earlier underwent spectral-domain optical coherence tomography (SD-OCT), fluorescein angiography (FA), and indocyanine green angiography (IA), as well as a routine ophthalmological examination. The patient's intraocular pressure, visual acuity, and visual field were within normal range. Ophthalmoscopy revealed a serous macular detachment, soft drusen, exudates, and a reddish-orange elevated lesion in the macula of the left eye. The right eye was normal. SD-OCT revealed two lesions in the left eye. One was a PED accompanied by a notch sign, and the other was a choroidal excavation. Additionally, FA revealed a window defect in the PED, and IA showed typical PCV. Three monthly injections of antivascular endothelial growth factor preserved visual acuity, but failed to have any visible effect on the lesion during the 6-month follow up period. This is the first report of choroidal excavation accompanied by PED and PCV. The data suggest that choroidal excavation may be associated with various changes that have not been previously reported. Careful observation of such cases may therefore be necessary.

  18. Excavations at Wodoku and Lodoku and their implications for the ...

    African Journals Online (AJOL)

    Finds from excavations at Wodoku and Ladoku, the original home of the Nungwa and La people respectively are described, and their implications for the archaeology of the Accra Plains, particularly as they relate to the pottery sequence, Ga-Dangme origins, chronology of settlements, economy and subsistence practices ...

  19. Complete excavation and mapping of a Texas leafcutting ant nest

    Science.gov (United States)

    John C. Moser

    2006-01-01

    A medium-sized nest of the Texas leafcutting ant, Atta texana (Buckley), in northern Louisiana was excavated completely, and a three-dimensional model of its external and subterranean features was constructed. In total, 97 fungus gardens, 27 dormancy cavities, and 45 detritus cavities were located. At the lower center of the funnel-shaped nest was a...

  20. Telemanipulation and supervisory control of a backhoe excavator

    Science.gov (United States)

    Luengo, Oscar; Barrientos, Antonio

    1998-12-01

    The excavation tasks present one of the more challenging area in robotic research. The environment is highly unstructured, the forces that appear are very large it is very important the detection of underground obstacles to avoid any damage, and the modeling of the hydraulic actuators is highly nonlinear. In recent years, the remote control of the excavation has found applications in very dangerous environments for human beings, like nuclear power plants, nuclear and chemical waste facilities and terrestrial and extra-terrestrial mining. Some kind of intelligence is required due to the presence of unexpected situations. The first approach to deal with the problem is to put a human being in the loop, that is: teleoperation. The next step towards the total automation of the excavation is the supervisory control of the task. In this scheme, the operator acts like a supervisor, providing high level commands, and checking the development and accomplishment of the task. The solutions that DISAM has developed are presented in this paper, as well as future work that will be very useful in the search for the total automation of excavation tasks.

  1. Choroidal excavation with polypoidal choroidal vasculopathy: a case report

    Directory of Open Access Journals (Sweden)

    Kobayashi W

    2012-08-01

    Full Text Available Wataru Kobayashi,1 Toshiaki Abe,2 Hiroshi Tamai,1 Toru Nakazawa11Department of Ophthalmology, 2Division of Clinical Cell Therapy, Center for Advanced Medical Research and Development (ART, Tohoku University Graduate School of Medical Science, Sendai, JapanPurpose: This is a report of a case of choroidal excavation accompanied by polypoidal choroidal vasculopathy (PCV and retinal pigment epithelium detachment (PED.Methods: A 57-year-old Japanese woman who had begun complaining of metamorphopsia in her left eye 7 months earlier underwent spectral-domain optical coherence tomography (SD-OCT, fluorescein angiography (FA, and indocyanine green angiography (IA, as well as a routine ophthalmological examination.Results: The patient’s intraocular pressure, visual acuity, and visual field were within normal range. Ophthalmoscopy revealed a serous macular detachment, soft drusen, exudates, and a reddish-orange elevated lesion in the macula of the left eye. The right eye was normal. SD-OCT revealed two lesions in the left eye. One was a PED accompanied by a notch sign, and the other was a choroidal excavation. Additionally, FA revealed a window defect in the PED, and IA showed typical PCV. Three monthly injections of antivascular endothelial growth factor preserved visual acuity, but failed to have any visible effect on the lesion during the 6-month follow up period.Conclusions: This is the first report of choroidal excavation accompanied by PED and PCV. The data suggest that choroidal excavation may be associated with various changes that have not been previously reported. Careful observation of such cases may therefore be necessary.Keywords: choroidal excavation, polypoidal choroidal vasculopathy, anti-vascular endothelial growth factor treatment

  2. Precision truing of diamond wheel with sharp edge

    Science.gov (United States)

    Ge, Cheng; Guo, Bing; Zhao, QIngliang; Chen, Bing; Wang, Jinhu

    2014-08-01

    Diamond wheel with sharp edge has small contour structures, which can lead to fast wear of wheel in the grinding process. Traditional truing methods are hard to apply to this kind of wheels. Therefore, as for the difficulty of precision truing of diamond wheel with sharp edge, the novel methods for resin and metal bonded diamond wheels with sharp edge are presented, respectively. In this experiment, a conditioning procedure with rare metal alloy block Ta was used to true the resin bonded diamond grinding wheel and in the same way Nb alloy block was utilized to complete rough truing of metal bonded diamond grinding wheel. Then a CNC truing technique with rotational green carbide (GC) truing stick was applied to precise truing of metal bonded diamond grinding wheel. Methods mentioned above were measured in order to evaluate the performance of truing. Geometric features of the wheel sharp edge were duplicated on the organic glass (PMMA) in order to measure and calculate the radius of the sharp edge. The edge radius of trued resin bonded wheel and metal bonded wheel is perceived as an important assessment. The experiments results revealed that the edge radius of 12.45μm for the resin bonded wheel and the edge radius of 30.17μm for the metal bonded wheel could be achieved.

  3. The twins and the bucket: How Einstein made gravity rather than motion relative in general relativity

    Science.gov (United States)

    Janssen, Michel

    2012-08-01

    In publications in 1914 and 1918, Einstein claimed that his new theory of gravity in some sense relativizes the rotation of a body with respect to the distant stars (a stripped-down version of Newton's rotating bucket experiment) and the acceleration of the traveler with respect to the stay-at-home in the twin paradox. What he showed was that phenomena seen as inertial effects in a space-time coordinate system in which the non-accelerating body is at rest can be seen as a combination of inertial and gravitational effects in a (suitably chosen) space-time coordinate system in which the accelerating body is at rest. Two different relativity principles play a role in these accounts: (a) the relativity of non-uniform motion, in the weak sense that the laws of physics are the same in the two space-time coordinate systems involved; (b) what Einstein in 1920 called the relativity of the gravitational field, the notion that there is a unified inertio-gravitational field that splits differently into inertial and gravitational components in different coordinate systems. I provide a detailed reconstruction of Einstein's rather sketchy accounts of the twins and the bucket and examine the role of these two relativity principles. I argue that we can hold on to (b) but that (a) is either false or trivial.

  4. Assessment of snowfall accumulation underestimation by tipping bucket gauges in the Spanish operational network

    Science.gov (United States)

    Buisán, Samuel T.; Earle, Michael E.; Luís Collado, José; Kochendorfer, John; Alastrué, Javier; Wolff, Mareile; Smith, Craig D.; López-Moreno, Juan I.

    2017-03-01

    Within the framework of the World Meteorological Organization Solid Precipitation Intercomparison Experiment (WMO-SPICE), the Thies tipping bucket precipitation gauge was assessed against the SPICE reference configuration at the Formigal-Sarrios test site located in the Pyrenees mountain range of Spain. The Thies gauge is the most widely used precipitation gauge by the Spanish Meteorological State Agency (AEMET) for the measurement of all precipitation types including snow. It is therefore critical that its performance is characterized. The first objective of this study is to derive transfer functions based on the relationships between catch ratio and wind speed and temperature. Multiple linear regression was applied to 1 and 3 h accumulation periods, confirming that wind is the most dominant environmental variable affecting the gauge catch efficiency, especially during snowfall events. At wind speeds of 1.5 m s-1 the tipping bucket recorded only 70 % of the reference precipitation. At 3 m s-1, the amount of measured precipitation decreased to 50 % of the reference, was even lower for temperatures colder than -2 °C and decreased to 20 % or less for higher wind speeds.The implications of precipitation underestimation for areas in northern Spain are discussed within the context of the present analysis, by applying the transfer function developed at the Formigal-Sarrios and using results from previous studies.

  5. Optically trapped and driven paddle-wheel

    OpenAIRE

    Asavei, T.; Nieminen, T.A.; Loke, V.L.Y.; Stilgoe, A.B.; Bowman, R.; Preece, D.; Padgett, M.J.; Heckenberg, N.R.; Rubinsztein-Dunlop, H.

    2013-01-01

    We demonstrate the control and rotation of an optically trapped object, an optical paddle-wheel, with the rotation direction normal to the beam axis. This is in contrast to the usual situation where the rotation is about the beam axis. The paddle-wheel can be optically driven and moved to any position in the field of view of the microscope, which can be of interest for various biological applications where controlled application of a fluid flow is needed in a particular location and in a spec...

  6. Steady state modeling of desiccant wheels

    DEFF Research Database (Denmark)

    Bellemo, Lorenzo; Elmegaard, Brian; Kærn, Martin Ryhl

    2014-01-01

    Desiccant wheels are rotary desiccant dehumidifiers used in air conditioning and drying applications. The modeling of simultaneous heat and mass transfer in these components is crucial for estimating their performances, as well as for simulating and optimizing their implementation in complete...... systems. A steady state two-dimensional model is formulated and implemented aiming to obtain good accuracy and short computational times. Comparison with experimental data from the literature shows that the model reproduces the physical behavior of desiccant wheels. Mass diffusion in the desiccant should...

  7. GEAR WHEELS THE PROCESSED BY ELECTRICAL EROSION

    Directory of Open Access Journals (Sweden)

    MARCEL S.POPA

    2015-12-01

    Full Text Available For low tooth loads and low peripheral speeds between 0.3 and 2 m / s are chosen based alloys and steels, gray cast iron. In industry are preferable ferrous alloys: bronze, brass and aluminum alloys, and where speeds and demands are low gears are made of sheet steel or alloys. Wheel group required less include some hand-operated mechanisms, such as jacks, some trolls. These wheels are larger and they are made of alloy steel, semi-hard and sometimes gray cast iron FC250, FC300.

  8. Maximum Torque and Momentum Envelopes for Reaction Wheel Arrays

    Science.gov (United States)

    Markley, F. Landis; Reynolds, Reid G.; Liu, Frank X.; Lebsock, Kenneth L.

    2009-01-01

    Spacecraft reaction wheel maneuvers are limited by the maximum torque and/or angular momentum that the wheels can provide. For an n-wheel configuration, the torque or momentum envelope can be obtained by projecting the n-dimensional hypercube, representing the domain boundary of individual wheel torques or momenta, into three dimensional space via the 3xn matrix of wheel axes. In this paper, the properties of the projected hypercube are discussed, and algorithms are proposed for determining this maximal torque or momentum envelope for general wheel configurations. Practical strategies for distributing a prescribed torque or momentum among the n wheels are presented, with special emphasis on configurations of four, five, and six wheels.

  9. 29 CFR 1926.913 - Blasting in excavation work under compressed air.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Blasting in excavation work under compressed air. 1926.913... Use of Explosives § 1926.913 Blasting in excavation work under compressed air. (a) Detonators and... use in wet holes shall be water-resistant and shall be Fume Class 1. (g) When tunnel excavation in...

  10. 29 CFR 570.68 - Occupations in excavation operations (Order 17).

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Occupations in excavation operations (Order 17). 570.68...-Being § 570.68 Occupations in excavation operations (Order 17). (a) Finding and declaration of fact. The following occupations in excavation operations are particularly hazardous for the employment of persons...

  11. Does the availability of artificial cavities affect cavity excavation rates in red-cockaded woodpeckers?

    Science.gov (United States)

    Richard N. Conner; Daniel Saenz; D. Craig Rudolph; Richard R. Schaefer

    2002-01-01

    Rates of cavity excavation by Red-cockaded Woodpeckers (Picoides borealis) were examined from 1983 to 1999 on the Angelina National Forest in east Texas. We compared the rare of natural cavity excavation between 1983 and 1990 (before artificial cavities were available) with the rate of cavity excavation between 1992 and 1993, a period when...

  12. 18 CFR 1304.207 - Channel excavation on TVA-owned residential access shoreland.

    Science.gov (United States)

    2010-04-01

    ... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Channel excavation on... OF STRUCTURES AND OTHER ALTERATIONS TVA-Owned Residential Access Shoreland § 1304.207 Channel excavation on TVA-owned residential access shoreland. (a) Excavation of individual boat channels shall be...

  13. A Review of Lunar Regolith Excavation Robotic Device Prototypes

    Science.gov (United States)

    Mueller, Robert P.; Van Susante, Paul J.

    2011-01-01

    The excavation of lunar regolith is desirable for use as a feedstock for oxygen production processes as well as civil engineering purposes and for the fabrication of parts and structures. This is known as In-Situ Resource Utilization (ISRU). More recently, there has been mounting evidence that water ice exists at the poles of the Moon, buried in the regolith where thermally stable conditions exist. This means that regolith excavation will be required to mine the water ice which is believed to be. mixed in with the regolith, or bonded to it. The mined water ice can then be electrolyzed to produce hydrogen and oxygen propellants which could form the basis of a cis-lunar transportation system using in-situ derived propellants. In 2007, the National Aeronautics & Space Administration (NASA) sponsored a Lunar Regolith Excavation Competition as part of its Centennial Challenges program, The competition was not won and it was held again in 2008 and 2009, when it was won by a university team. A $500,000 prize was awarded to the winning team by NASA. In 2010, NASA continued the competition as a spinoff of the Centennial Challenges, which is restricted to university participation only. This competition is known as the "Lunabotics Mining Competition" and is hosted by NASA at Kennedy Space Center. Twenty three American university teams competed in the 2010 Lunabotics Mining Competition. The competition was held again in May 2011 with over 60 teams registered, including international participation. The competition will be held again in May 2012 at Kennedy Space Center in Florida. . This paper contains a thorough review of the various regolith eX,cavation robotic device prototypes that competed in these NASA competitions, and will. classify the machines and their methods of excavation to document the variety of ideas that were spawned and built to compete at these events. It is hoped that documentation of these robots will serve to help future robotic excavation designers and

  14. Experimental Investigation on the Aerodynamics of Isolated Rotating Wheels and Evaluation of Wheel Rotation Models Using Unsteady CFD

    National Research Council Canada - National Science Library

    Haag, Lukas; Blacha, Thomas; Indinger, Thomas

    2017-01-01

    .... In modern wind-tunnels the wheel rotation can be resembled close to reality, while, in their CFD development process, car manufactures rely on simplified models for considering rotating wheels...

  15. 14 CFR 23.497 - Supplementary conditions for tail wheels.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Supplementary conditions for tail wheels... Structure Ground Loads § 23.497 Supplementary conditions for tail wheels. In determining the ground loads on the tail wheel and affected supporting structures, the following apply: (a) For the obstruction load...

  16. Disturbances in reaction wheels; from measurement to modelling

    NARCIS (Netherlands)

    Le, M.P.; Ellenbroek, Marcellinus Hermannus Maria; Seiler, R; van Put, P.; Cottaar, E.J.E.

    2014-01-01

    Disturbances in reaction wheels have been long a crucial aspect for many scientific observation missions. An accurate and reliable disturbance model to understand and evaluate the influence of reaction wheel disturbances to the spacecraft is critically needed. Several reaction wheel disturbance

  17. 16 CFR 1512.12 - Requirements for wheel hubs.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Requirements for wheel hubs. 1512.12 Section... REGULATIONS REQUIREMENTS FOR BICYCLES Regulations § 1512.12 Requirements for wheel hubs. All bicycles (other than sidewalk bicycles) shall meet the following requirements: (a) Locking devices. Wheels shall be...

  18. 14 CFR 23.745 - Nose/tail wheel steering.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Nose/tail wheel steering. 23.745 Section 23.745 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... Landing Gear § 23.745 Nose/tail wheel steering. (a) If nose/tail wheel steering is installed, it must be...

  19. 14 CFR 25.497 - Tail-wheel yawing.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Tail-wheel yawing. 25.497 Section 25.497... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.497 Tail-wheel yawing. (a) A vertical ground reaction equal to the static load on the tail wheel, in combination with a side component of equal...

  20. All-wheel drive and winter-weather safety.

    Science.gov (United States)

    2013-03-01

    It is frequently stated that people living in northern states, the so called Snowbelt of the United : States, benefit with respect to safety from driving all-wheel or four-wheel drive vehicles as : opposed to front or rear-wheel drive only. This stud...

  1. 29 CFR 1910.215 - Abrasive wheel machinery.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 5 2010-07-01 2010-07-01 false Abrasive wheel machinery. 1910.215 Section 1910.215 Labor... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Machinery and Machine Guarding § 1910.215 Abrasive wheel machinery. (a) General requirements—(1) Machine guarding. Abrasive wheels shall be used only on machines provided with...

  2. 49 CFR 229.75 - Wheels and tire defects.

    Science.gov (United States)

    2010-10-01

    ... inch thick on a locomotive in road service or less than 3/4 inch on a locomotive in yard service. (k) A... may not be used on tires or steel wheels of locomotives, except for the repair of flat spots and worn flanges on locomotives used exclusively in yard service. A wheel that has been welded is a welded wheel...

  3. Rolling Friction on a Wheeled Laboratory Cart

    Science.gov (United States)

    Mungan, Carl E.

    2012-01-01

    A simple model is developed that predicts the coefficient of rolling friction for an undriven laboratory cart on a track that is approximately independent of the mass loaded onto the cart and of the angle of inclination of the track. The model includes both deformation of the wheels/track and frictional torque at the axles/bearings. The concept of…

  4. Performance Evaluation of Abrasive Grinding Wheel Formulated ...

    African Journals Online (AJOL)

    This paper presents a study on the formulation and manufacture of abrasive grinding wheel using locally formulated silicon carbide abrasive grains. Six local raw material substitutes were identified through pilot study and with the initial mix of the identified materials, a systematic search for an optimal formulation of silicon ...

  5. Omnidirectional Wheel-Legged Hybrid Mobile Robot

    Directory of Open Access Journals (Sweden)

    István Vilikó

    2015-06-01

    Full Text Available The purpose of developing hybrid locomotion systems is to merge the advantages and to eliminate the disadvantages of different type of locomotion. The proposed solution combines wheeled and legged locomotion methods. This paper presents the mechatronic design approach and the development stages of the prototype.

  6. On equitable coloring of corona of wheels

    Directory of Open Access Journals (Sweden)

    J. Vernold Vivin

    2016-10-01

    Full Text Available The notion of equitable colorability was introduced by Meyer in $1973$ \\cite{meyer}. In this paper we obtain interesting results regarding the equitable chromatic number $\\chi_{=}$ for the corona graph of a simple graph with a wheel graph $G\\circ W_n$. Some extensions into $l$-corona products are also determined.

  7. Investigating Functions with a Ferris Wheel

    Science.gov (United States)

    Johnson, Heather Lynn; Hornbein, Peter; Azeem, Sumbal

    2016-01-01

    The authors provide a dynamic Ferris wheel computer activity that teachers can use as an instructional tool to help students investigate functions. They use a student's work to illustrate how students can use relationships between quantities to further their thinking about functions.

  8. Reinventing the Wheel: Design and Problem Solving

    Science.gov (United States)

    Blasetti, Sean M.

    2010-01-01

    This article describes a design problem that not only takes students through the technological design process, but it also provides them with real-world problem-solving experience as it relates to the manufacturing and engineering fields. It begins with a scenario placing the student as a custom wheel designer for an automotive manufacturing…

  9. Examination of a failed fifth wheel coupling

    CSIR Research Space (South Africa)

    Fernandes, PJL

    1998-03-01

    Full Text Available Examination of a fifth wheel coupling which had failed in service showed that it had been modified and that the operating handle had been moved from its original design position. This modification completely eliminated the safety device designed...

  10. Various Tunnel Excavation Methods used on the LHC Project

    CERN Document Server

    Fielder, R

    2000-01-01

    Civil Engineering construction work for the LHC Project began in April 1998 and is now well underway. A major part of this work is the construction of the new tunnels, caverns and cavern enlargements for the LHC experiments and machine. Currently, this underground work is being carried out for the two injection tunnels, TI2 and TI8, and at Point 1 for the Atlas Experiment. There are three contractors involved in these tunnelling works and each contactor is using a different technique. This paper will outline the different methods used for excavation and the reasons for these differences. It will also examine the other operations involved in the construction of major underground structures such as supply of materials to the tunnel face, evacuation of excavated material and ventilation.

  11. Hierarchical stochastic model of terrain subsidence during tunnel excavation

    Science.gov (United States)

    Janda, Tomáš; Šejnoha, Jiří; Šejnoha, Michal

    2017-09-01

    In this contribution the Bayesian statistical method is applied to assess the expected probability distribution of the terrain subsidence in the course of tunnel excavation. The approach utilizes a number of simplifying assumptions regarding the system kinematics to arrive at a very simple model with just a few degrees of freedom. This deterministic model together with the intrinsic uncertainties of its parameters and measurement inaccuracies are used to formulate the stochastic model which defines a distribution of the predicted values of terrain subsidence. Assuming the measured data to be fixed, the stochastic model thus defines the likelihood function of the model parameters which is directly used for updating their prior distribution. This way the model parameters can be incrementally updated with each excavation step and the prediction of the model refined.

  12. The excavation stage of basin formation - A qualitative model

    Science.gov (United States)

    Croft, S. K.

    1981-01-01

    One of the most complex problems in planetary geology and geophysics is the determination of the nature of the impact cratering processes at scales of tens to thousands of kilometers that produce the complex morphological structures of multiring basins. The cratering process is frequently considered to be divided into three stages, including a short high-pressure stage of initial contact between the projectile and the planetary crust, a longer excavation or cratering flow stage culminating in the formation of a transient crater, and a still longer modification stage during which the transient crater is modified into the observed final geologic form. The transient crater may be considered as the initial boundary condition of the modification stage. In the present investigation, the nature of the transient crater is indicated by the cratering flow field determined from numerical simulations of the excavation stage. Attention is given to empirical and theoretical scaling.

  13. Real-Time Engineering Simulation of Lunar Excavation

    Energy Technology Data Exchange (ETDEWEB)

    Bruce Damer, George Tompkins, Sheldon Freid, Dave Rasmussen, Peter Newman, Brad Blair

    2007-06-12

    DigitalSpace Corporation has been building an open source real-time three-dimensional (3-D) collaborative design engineering and training platform called Digital Spaces (DSS) in support of the Exploration Vision of the National Aeronautics and Space Administration (NASA). Real-time 3-D simulation has reached a level of maturity where it is capable of supporting engineering design and operations using off-the-shelf game chipsets and open source physics and rendering technologies. This paper will illustrate a state-of-the-art real-time engineering simulation utilizing DSS in support of NASA lunar excavation studies. During the project DigitalSpace building driveable 3-D models of lunar excavators and South Polar terrain, and added a soil mechanics physics model as well as a random failure generator to the repertoire of standard mobility platform physics in prior use for real-time engineering and operational analysis at NASA.

  14. Emergency Survey and Excavation in Southwestern New Mexico.

    Science.gov (United States)

    1980-01-01

    Period 90 * The Apache 90 The Spanish, Mexican, and American Occupations 90 ii *li APPENDIX B - BOTANICAL RIMAIS 92 Mollie Struever and Marcia Donaldson...probably the scene of seasonal mesquite-gathering and hunting expeditions. The Cochise Cul- ture is also known from Tularosa and Cordova Caves near the upper... Cordova Caves (Martin and Rinaldo 1952). Additional chronology was provided by excavations in Bat Cave (Dick 1965). Tentatively dated at 300 B.C., the

  15. Behavioral and mechanical determinants of collective subsurface nest excavation.

    Science.gov (United States)

    Monaenkova, Daria; Gravish, Nick; Rodriguez, Greggory; Kutner, Rachel; Goodisman, Michael A D; Goldman, Daniel I

    2015-05-01

    Collective construction of topologically complex structures is one of the triumphs of social behavior. For example, many ant species construct underground nests composed of networks of tunnels and chambers. Excavation by these 'superorganisms' depends on the biomechanics of substrate manipulation, the interaction of individuals, and media stability and cohesiveness. To discover principles of robust social excavation, we used X-ray computed tomography to monitor the growth in three dimensions of nests built by groups of fire ants (Solenopsis invicta) in laboratory substrates composed of silica particles, manipulating two substrate properties: particle size and gravimetric moisture content. Ants were capable of nest construction in all substrates tested other than completely dry or fully saturated; for a given particle size, nest volume was relatively insensitive to moisture content. Tunnels were deepest at intermediate moisture content and the maximum tunnel depth correlated with measured yield force on small rod-shaped intruders (a proxy for cohesive strength). This implies that increased cohesive strength allowed creation of tunnels that were resistant to perturbation but did not decrease individual excavation ability. Ants used two distinct behaviors to create pellets composed of wetted particles, depending on substrate composition. However, despite the ability to create larger stable pellets in more cohesive substrates, pellet sizes were similar across all conditions. We posit that this pellet size balances the individual's load-carrying ability with the need to carry this pellet through confined crowded tunnels. We conclude that effective excavation of similarly shaped nests can occur in a diversity of substrates through sophisticated digging behaviors by individuals which accommodate both differing substrate properties and the need to work within the collective. © 2015. Published by The Company of Biologists Ltd.

  16. The Application of Foundation Pit Monitoring Technology to the Excavation

    OpenAIRE

    Qiu Jin; Li Fei

    2015-01-01

    The foundation pit monitoring plays an important role in the foundation pit supporting projects especially in those deep foundation pit projects. Through the whole monitoring of the foundation pit construction from the excavation to the backfill, we can learn about the forcing and deforming process of the foundation pit supporting system, and grasp the impact of external condition changes on the foundation pit. This paper takes a project in Jinan as an example to establish a specific monitori...

  17. Storage solutions for excavated textiles tending to their recalcitrant behaviour

    DEFF Research Database (Denmark)

    Margariti, Christina; Loukopoulou, Polytimi

    2016-01-01

    This paper discusses the selection of packaging and storage means that facilitate the preservation, protection andmanagerial needs for a group of excavated textiles where their physical and chemical properties have been unrecognisably altered as a result of the burial process (in this case minera...... foam, copolymer polyethylene and polypropylene board, non-woven polyethylene fabric and the antistatic type of polyester film. All materials and methods applied exhibit great versatility and are potentially useful for conservators in similar situations....

  18. 77 FR 67400 - RG Steel Wheeling, LLC, a Division of RG Steel, LLC, Doing Business as Wheeling Corrugating...

    Science.gov (United States)

    2012-11-09

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF LABOR Employment and Training Administration RG Steel Wheeling, LLC, a Division of RG Steel, LLC, Doing Business as Wheeling Corrugating Company, Including Workers Whose Wages Were Reported Through Severstal Wheeling, Beech Bottom, WV; Amended Certification...

  19. Umbrella Wheel - a stair-climbing and obstacle-handling wheel design concept

    DEFF Research Database (Denmark)

    Iversen, Simon; Jouffroy, Jerome

    This paper proposes a new design for stair-climbing using a wheel that can split into segments and walk up stairs or surmount other obstacles often found where humans traverse, while still being able to retain a perfectly round shape for traveling on smooth ground. Using this change of configurat......This paper proposes a new design for stair-climbing using a wheel that can split into segments and walk up stairs or surmount other obstacles often found where humans traverse, while still being able to retain a perfectly round shape for traveling on smooth ground. Using this change...... of configuration, staircases with a wide range of dimensions can be covered efficiently and safely. The design, named Umbrella Wheel, can consist of as many wheel segments as desired, and as few as two. A smaller or higher number of wheel segments has advantages and disadvantages depending on the specific...... situation. Modeling the trajectory of the wheel when as it ascends or descends stairs is given and the results are analyzed....

  20. Umbrella Wheel - a stair-climbing and obstacle-handling wheel design concept

    DEFF Research Database (Denmark)

    Iversen, Simon; Jouffroy, Jerome

    2017-01-01

    This paper proposes a new design for stair-climbing using a wheel that can split into segments and walk up stairs or surmount other obstacles often found where humans traverse, while still being able to retain a perfectly round shape for traveling on smooth ground. Using this change of configurat......This paper proposes a new design for stair-climbing using a wheel that can split into segments and walk up stairs or surmount other obstacles often found where humans traverse, while still being able to retain a perfectly round shape for traveling on smooth ground. Using this change...... of configuration, staircases with a wide range of dimensions can be covered efficiently and safely. The design, named Umbrella Wheel, can consist of as many wheel segments as desired, and as few as two. A smaller or higher number of wheel segments has advantages and disadvantages depending on the specific...... situation. Modeling the trajectory of the wheel when as it ascends or descends stairs is given and the results are analyzed....

  1. Design of Wheeled Mobile Robot with Tri-Star Wheel as Rescue Robot

    Directory of Open Access Journals (Sweden)

    Rafiuddin Syam

    2014-10-01

    Full Text Available This study aims to design, and analyze a mobile robot that can handle some of the obstacles, they are uneven surfaces, slopes, can also climb stairs. WMR in this study is Tristar wheel that is containing three wheels for each set. On average surface only two wheels in contact with the surface, if there is an uneven surface or obstacle then the third wheel will rotate with the rotation center of the wheel in contact with the leading obstacle then only one wheel in contact with the surface. This study uses the C language program. Furthermore, the minimum thrust to be generated torque of the motor and transmission is 9.56 kg. The results obtained by calculation and analysis of DC motors used must have a torque greater than 14.67 kg.cm. Minimum thrust to be generated motor torque and the transmission is 9.56 kg. The experimental results give good results for robot to moving forward, backward, turn left, turn right and climbing the stairs.

  2. Lunar Excavation Experiments in Simulant Soil Test Beds-Revisiting the Surveyor Geotechnical Data

    Science.gov (United States)

    Agui, Juan H.; Wilkinson, R. Allen

    2012-01-01

    (1) Establishing ISRU technologies on planetary bodies is an important long-term goal of NASA; (2) Excavation is a key component of these ISRU processes; (3) Lack of flight data relevant to lunar excavation; (4) Existing models of the excavation-cutting phenomenon give varying results; (5) The lack of predictive models of the dynamic behavior of soils in excavation implements is a major driver for these studies; and (6) Objective: Need to develop robust models of excavation cutting phenomena that generate predictive capabilities to aid the designer and engineer.

  3. Large choroidal excavation in a patient with rubella retinopathy.

    Science.gov (United States)

    Battaglia Parodi, Maurizio; Romano, Francesco; Montagna, Marco; Bandello, Francesco

    2017-10-17

    To describe a case of rubella retinopathy complicated by bilateral choroidal neovascularization (CNV) and late development of large choroidal excavation (LCE). A 19-year-old woman with a diagnosis of rubella retinopathy underwent her annual ophthalmologic examination, including visual acuity testing and slit-lamp biomicroscopy with dilated fundus examination. Color fundus photography, spectral-domain optical coherence tomography (SD-OCT) scans, and optical coherence tomography angiography were acquired to complete the investigation of her ocular condition. The main findings are described in this case report. This woman came to our attention in 2010 with a history of rubella retinopathy, complicated by bilateral CNV and treated with photodynamic therapy (PDT) in 2006. After 6 years of annual follow-up examinations, her visual acuity remained stable in both eyes (20/100), whereas SD-OCT scans uncovered the development of a bilateral LCE in the macular area, associated with a macular hole in the right eye. Optical coherence tomography angiography revealed a vascular network surrounding the choroidal excavation. Large choroidal excavation is a rare finding that has been described in few chorioretinal diseases, e.g., North Carolina macular dystrophy and toxoplasmosis. We propose to include rubella retinopathy complicated by CNV in the differential diagnosis of LCE, although we recognize the possibility that PDT might have induced or facilitated its formation.

  4. Soil Lysimeter Excavation for Coupled Hydrological, Geochemical, and Microbiological Investigations.

    Science.gov (United States)

    Sengupta, Aditi; Wang, Yadi; Meira Neto, Antonio A; Matos, Katarena A; Dontsova, Katerina; Root, Rob; Neilson, Julie W; Maier, Raina M; Chorover, Jon; Troch, Peter A

    2016-09-11

    Studying co-evolution of hydrological and biogeochemical processes in the subsurface of natural landscapes can enhance the understanding of coupled Earth-system processes. Such knowledge is imperative in improving predictions of hydro-biogeochemical cycles, especially under climate change scenarios. We present an experimental method, designed to capture sub-surface heterogeneity of an initially homogeneous soil system. This method is based on destructive sampling of a soil lysimeter designed to simulate a small-scale hillslope. A weighing lysimeter of one cubic meter capacity was divided into sections (voxels) and was excavated layer-by-layer, with sub samples being collected from each voxel. The excavation procedure was aimed at detecting the incipient heterogeneity of the system by focusing on the spatial assessment of hydrological, geochemical, and microbiological properties of the soil. Representative results of a few physicochemical variables tested show the development of heterogeneity. Additional work to test interactions between hydrological, geochemical, and microbiological signatures is planned to interpret the observed patterns. Our study also demonstrates the possibility of carrying out similar excavations in order to observe and quantify different aspects of soil-development under varying environmental conditions and scale.

  5. ROCK MASS DAMAGED ZONE CAUSED BY BLASTING DURING TUNNEL EXCAVATION

    Directory of Open Access Journals (Sweden)

    Hrvoje Antičević

    2012-07-01

    Full Text Available Design of underground spaces, including tunnels, and repositories for radioactive waste include the application of the same or similar technologies. Tunnel excavation by blasting inevitably results in the damage in the rock mass around the excavation profile. The damage in the rock mass immediately next to the tunnel profile emerges as the expanding of the existing cracks and the appearance of new cracks, i.e. as the change of the physical and-mechanical properties of the rock mass. Concerning the design of deep geological repositories, requirements in terms of damaged rock are the same or more rigorous than for the design of tunnel. The aforementioned research is directed towards determining the depth of damage zone caused by blasting. The depth of the damage zone is determined by measuring the changes of physical and-mechanical properties of the rock mass around the tunnel excavation profile. By this research the drilling and blasting parameters were correlated with the depth and size of the damage zone (the paper is published in Croatian.

  6. A load-displacement based approach to assess the bearing capacity and deformations of mono-bucket foundations

    DEFF Research Database (Denmark)

    Vahdatirad, Mohammadjavad; Diaz, Alberto Troya; Nielsen, Søren

    2016-01-01

    It is now accepted that a larger effort must be made in order to optimize the design so that offshore wind turbines can be competitive with the other energy resources. In this regard, mono-buckets are known as a cost-effective offshore foundation solution. In the current study, a load...

  7. Silica exposure to excavation workers during the excavation of a low level radiological waste pit and tritium disposal shafts

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, K.M.

    1995-01-01

    This study evaluated the task-length average (TLA) respirable dust and respirable silica airborne concentrations to which construction workers excavating volcanic tuff at Los Alamos National Laboratory (LANL) were exposed. These workers were excavating a low level radiological waste disposal pit of final dimensions 720 feet long, 132 feet wide and 60 feet deep. The objectives of this study were as follows: (1) evaluate exposures; (2) determine if the type of machinery used affects the respirable dust concentration in the breathing zone of the worker; (3) evaluate the efficacy of wetting the pit to reduce the respirable dust exposure; and (4) determine if exposure increases with increasing depth of pit due to the walls of the pit blocking the cross wind ventilation.

  8. The Running Wheel Enhances Food Anticipatory Activity: An Exploratory Study.

    Science.gov (United States)

    Flôres, Danilo E F L; Bettilyon, Crystal N; Jia, Lori; Yamazaki, Shin

    2016-01-01

    Rodents anticipate rewarding stimuli such as daily meals, mates, and stimulant drugs. When a single meal is provided daily at a fixed time of day, an increase in activity, known as food anticipatory activity (FAA), occurs several hours before feeding time. The factors affecting the expression of FAA have not been well-studied. Understanding these factors may provide clues to the undiscovered anatomical substrates of food entrainment. In this study we determined whether wheel-running activity, which is also rewarding to rodents, modulated the robustness of FAA. We found that access to a freely rotating wheel enhanced the robustness of FAA. This enhancement was lost when the wheel was removed. In addition, while prior exposure to a running wheel alone did not enhance FAA, the presence of a locked wheel did enhance FAA as long as mice had previously run in the wheel. Together, these data suggest that FAA, like wheel-running activity, is influenced by reward signaling.

  9. Orbiter Payload Bay Bucket Hoist Mishap...An Accident We Should Never Forget

    Science.gov (United States)

    Lytle, Bradford P.

    2009-01-01

    This slide presentation reviews the accident that occurred in 1985 when a bay bucket hoist fell from its stowed position. This accident damaged the orbiter, injured a technician, and delayed the launch. The accident was investigated, and the cause of the accident was determined to be the practice of two-blocking. Two-blocking is the result of hoisting beyond the intended safe upper limit of hook travel to the point of solid contact between the load block and the upper block or hoist/trolley structure. The usual result is immediate failure of the wire rope, due to the ropes being cut by the grooves of the drum or sheaves. The design of the hoist, the inspection, and the operator training were all in part responsible for this failure.

  10. Wave Forces on Transition Pieces for Bucket Foundations for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Nezhentseva, Anastasia; Andersen, Thomas Lykke; Andersen, Lars Vabbersgaard

    Since offshore wind turbines continually increase in size and move to deep water depths (>25 m), significant wave loading becomes a major concern for their design. A monopile foundation is one of the most commonly used types of the offshore wind turbine foundations today. This solution, however...... to a bucket foundation (suction caisson) located at 35 m water depth in the North Sea. Several models of the TPs (wedge-shaped steel flange-reinforced shear panels, conical and doubly curved with or without cutaways) are tested in a wave flume and compared with respect to wave loading. Due to a larger size...... of the suggested TPs compared to a typical slender monopole foundation, wave loads acting on these TPs are also expected to be considerably higher and much more difficult to predict. The results of the present investigation can be further applied for other wind turbine types....

  11. Seepage Study for Suction Installation of Bucket Foundation in Different Soil Combinations

    DEFF Research Database (Denmark)

    Koteras, Aleksandra Katarzyna; Ibsen, Lars Bo; Clausen, Johan Christian

    2016-01-01

    and additionally reduces the soil penetration resistance. This installation process is the most effective in soil with high coefficient of permeability where the flow of pore water is easily induced. However, the technology is still under development and some issues require further investigation and reliable...... and different boundaries. The flow of pore water is studied for homogenous sand, sand overlaid by impermeable layer and sand situated above impermeable layer. In all three cases the seepage analysis gives the required information on the critical suction pressure and on the distribution of excess pore pressure...... around the bucket skirt. The exceedance of critical suction might lead to installation failure due to formation of piping channels, which break the hydraulic seal between the skirt and soil. The excess pore pressure arising due to applied suction changes the effective stress, hence the penetration...

  12. PEMBATAS KECEPATAN DATA PADA PC-ROUTER BERBASIS LINUX MENGGUNAKAN DISIPLIN ANTRIAN HIERARCHICAL TOKEN BUCKET (HTB

    Directory of Open Access Journals (Sweden)

    Hari Siswantoro

    2007-08-01

    Full Text Available A common problem which occurred on a network router is bottle-neck phenomenon. This problem appear if the router is connecting high speed network (e.g. a 100 Mbps fast ethernet LAN to low speed network (e.g. 512 kbps DSL internet line. To avoid traffic congestion, there must be a mechanism to control the link sharing. This paper discusses the use of Hierarchical Token Bucket (HTB algorithm, which is embedded in Linux kernel, to share the bandwidth on a link in a controlled fashion. Hierarchical link sharing allows multiple hosts, agencies, or protocol families to share the bandwidth. By implementing the HTB algorithm, we intend to achieve a fair bandwidth sharing according to the policy

  13. Structural Optimization of an Offshore Wind Turbines Transition Pieces for Bucket Foundations

    DEFF Research Database (Denmark)

    Nezhentseva, Anastasia; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo

    in residual soil conditions for depths up to approximately 40 m. The existing design practice is limited to the use of steel-flange-reinforced shear panels. Desirable outcome is proposal of an alternative material which does not require extensive welding work. Compact reinforced composite (CRC) is suggested....... Three construction materials were proposed: CRC with main reinforcement, composite CRC‒steel shell elements and steel sheets (reference case). The conical shape of the TP structure has been found to provide the smooth transition of forces from the wind turbine tower down to the bucket skirt. Doubly...... curved segments have been introduced between the conical part and the tubular parts of the structure. While the minimum amount of steel and concrete was required for the composite CRC–steel shell model, the pure CRC model appeared to be the least sensitive to geometrical imperfections, corresponding...

  14. Multi-leg Seat Inventory Control Based on EMSU and Virtual Bucket

    Directory of Open Access Journals (Sweden)

    Wei Fan

    2014-01-01

    Full Text Available Expected marginal seat revenue (EMSR is a well-known method for airline seat inventory control airlines. However, this method employs a static model to study the dynamic reservation process, and does not take into account the risk tolerance of policy makers. Expected marginal seat utility (EMSU replaces revenue by utility, which addresses the real situation of seat inventory control. However, there is still a lack of multi-leg seat control algorithms based on EMSU. Therefore, using EMSU and bucket algorithms, this paper applies the Markov decision-making process to simulate the flight reservation process and builds a dynamic multi-leg seat inventory control model. Experimental results validate the effectiveness of the proposed method.

  15. Seepage Study for Suction Installation of Bucket Foundation in Different Soil Combinations

    DEFF Research Database (Denmark)

    Koteras, Aleksandra Katarzyna; Ibsen, Lars Bo; Clausen, Johan Christian

    2016-01-01

    around the bucket skirt. The exceedance of critical suction might lead to installation failure due to formation of piping channels, which break the hydraulic seal between the skirt and soil. The excess pore pressure arising due to applied suction changes the effective stress, hence the penetration...... and additionally reduces the soil penetration resistance. This installation process is the most effective in soil with high coefficient of permeability where the flow of pore water is easily induced. However, the technology is still under development and some issues require further investigation and reliable...... resistance of soil. Therefore, both matters are important for the design. The results show that the appearance of the impermeable layer above or below sand affects the excess pore pressure in this layer. Moreover, it has been found that the appearance of impermeable layer increases the allowable suction...

  16. Design of Transition Pieces for Bucket Foundations for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Nezhentseva, Anastasia

    -Reinforced Concrete (UHPFRC) with dense main reinforcement. A study on workability of UHPFRC material, compressive strength, and non-destructive Computed Tomography (CT-scanning) tests for analysis of fibre orientation, distribution and presence of cracks and air voids were carried out on a batch of UHPFRC samples...... with the suction bucket used as a monopod foundation for an offshore wind turbine. Traditionally, this part is made of steel triangular flange-reinforced shear panels (stiffeners) which require expensive production, corrosion protection, and suffer from fatigue at the welded joints due to cyclic loading produced......, potentially, minimize scour and wave loading on the TPs. Several shapes of TPs were selected for scour evaluation under constant unidirectional currents, and “clear water” and “live bed” regimens were generated in a small-scale facility. Development of the scour hole geometry, the scour volume...

  17. Large Aperture "Photon Bucket" Optical Receiver Performance in High Background Environments

    Science.gov (United States)

    Vilnrotter, Victor A.; Hoppe, D.

    2011-01-01

    The potential development of large aperture groundbased "photon bucket" optical receivers for deep space communications, with acceptable performance even when pointing close to the sun, is receiving considerable attention. Sunlight scattered by the atmosphere becomes significant at micron wavelengths when pointing to a few degrees from the sun, even with the narrowest bandwidth optical filters. In addition, high quality optical apertures in the 10-30 meter range are costly and difficult to build with accurate surfaces to ensure narrow fields-of-view (FOV). One approach currently under consideration is to polish the aluminum reflector panels of large 34-meter microwave antennas to high reflectance, and accept the relatively large FOV generated by state-of-the-art polished aluminum panels with rms surface accuracies on the order of a few microns, corresponding to several-hundred micro-radian FOV, hence generating centimeter-diameter focused spots at the Cassegrain focus of 34-meter antennas. Assuming pulse-position modulation (PPM) and Poisson-distributed photon-counting detection, a "polished panel" photon-bucket receiver with large FOV will collect hundreds of background photons per PPM slot, along with comparable signal photons due to its large aperture. It is demonstrated that communications performance in terms of PPM symbol-error probability in high-background high-signal environments depends more strongly on signal than on background photons, implying that large increases in background energy can be compensated by a disproportionally small increase in signal energy. This surprising result suggests that large optical apertures with relatively poor surface quality may nevertheless provide acceptable performance for deep-space optical communications, potentially enabling the construction of cost-effective hybrid RF/optical receivers in the future.

  18. Transmissibility of the Ice Bucket Challenge among globally influential celebrities: retrospective cohort study

    Science.gov (United States)

    Chan, Brandford H Y; Leung, Gabriel M; Lau, Eric H Y; Pang, Herbert

    2014-01-01

    Objectives To estimate the transmissibility of the Ice Bucket Challenge among globally influential celebrities and to identify associated risk factors. Design Retrospective cohort study. Setting Social media (YouTube, Facebook, Twitter, Instagram). Participants David Beckham, Cristiano Ronaldo, Benedict Cumberbatch, Stephen Hawking, Mark Zuckerberg, Oprah Winfrey, Homer Simpson, and Kermit the Frog were defined as index cases. We included contacts up to the fifth generation seeded from each index case and enrolled a total of 99 participants into the cohort. Main outcome measures Basic reproduction number R0, serial interval of accepting the challenge, and odds ratios of associated risk factors based on fully observed nomination chains; R0 is a measure of transmissibility and is defined as the number of secondary cases generated by a single index in a fully susceptible population. Serial interval is the duration between onset of a primary case and onset of its secondary cases. Results Based on the empirical data and assuming a branching process we estimated a mean R0 of 1.43 (95% confidence interval 1.23 to 1.65) and a mean serial interval for accepting the challenge of 2.1 days (median 1 day). Higher log (base 10) net worth of the participants was positively associated with transmission (odds ratio 1.63, 95% confidence interval 1.06 to 2.50), adjusting for age and sex. Conclusions The Ice Bucket Challenge was moderately transmissible among a group of globally influential celebrities, in the range of the pandemic A/H1N1 2009 influenza. The challenge was more likely to be spread by richer celebrities, perhaps in part reflecting greater social influence. PMID:25514905

  19. Transmissibility of the Ice Bucket Challenge among globally influential celebrities: retrospective cohort study.

    Science.gov (United States)

    Ni, Michael Y; Chan, Brandford H Y; Leung, Gabriel M; Lau, Eric H Y; Pang, Herbert

    2014-12-16

    To estimate the transmissibility of the Ice Bucket Challenge among globally influential celebrities and to identify associated risk factors. Retrospective cohort study. Social media (YouTube, Facebook, Twitter, Instagram). David Beckham, Cristiano Ronaldo, Benedict Cumberbatch, Stephen Hawking, Mark Zuckerberg, Oprah Winfrey, Homer Simpson, and Kermit the Frog were defined as index cases. We included contacts up to the fifth generation seeded from each index case and enrolled a total of 99 participants into the cohort. Basic reproduction number R0, serial interval of accepting the challenge, and odds ratios of associated risk factors based on fully observed nomination chains; R0 is a measure of transmissibility and is defined as the number of secondary cases generated by a single index in a fully susceptible population. Serial interval is the duration between onset of a primary case and onset of its secondary cases. Based on the empirical data and assuming a branching process we estimated a mean R0 of 1.43 (95% confidence interval 1.23 to 1.65) and a mean serial interval for accepting the challenge of 2.1 days (median 1 day). Higher log (base 10) net worth of the participants was positively associated with transmission (odds ratio 1.63, 95% confidence interval 1.06 to 2.50), adjusting for age and sex. The Ice Bucket Challenge was moderately transmissible among a group of globally influential celebrities, in the range of the pandemic A/H1N1 2009 influenza. The challenge was more likely to be spread by richer celebrities, perhaps in part reflecting greater social influence. © Ni et al 2014.

  20. The development of a material model and wheel-tissue interaction for simulating wheeled surgical robot mobility.

    Science.gov (United States)

    Rentschler, Mark E; Reid, John D

    2009-04-01

    In vivo surgical robot wheel and tissue interaction was studied using a nonlinear finite element model. A liver material model, derived from laboratory experiments, was implemented as a viscoelastic material. A finite element simulation of this laboratory test confirmed the accuracy of the liver material model. This material model was then used as the tissue model to study wheel performance. A helical wheel moving on the liver model was used to replicate laboratory experiments that included several different slip ratios and applied loads. The drawbar force produced in this model showed good agreement with the physical tests. These results have provided the baseline for studying how changes in wheel geometry, such as tread height, tread spacing and wheel diameter, affect drawbar force and ultimately wheel performance. These results will be used in future surgical robot wheel designs.

  1. Wheeled and Tracked Vehicle Endurance Testing

    Science.gov (United States)

    2014-10-02

    board power, and lift /tow (wreckers) to identify equipment damage or degradation. When establishing test mileage cycles, identify the number of...Standing Operating Procedures (SOPs) throughout test operations. b. Maintain correct levels of standard military lubricants, hydraulic fluids...Trailer, Light and Medium 50 40 10 a - Wheeled Truck-Tractor and Trailer, Heavy 40 45 15 a - Motorcycle 10 10 50 30 Quad / All Terrain

  2. Influence of wheel configuration on wheelchair basketball performance: wheel stiffness, tyre type and tyre orientation.

    Science.gov (United States)

    Mason, B S; Lemstra, M; van der Woude, L H V; Vegter, R; Goosey-Tolfrey, V L

    2015-04-01

    The aim of the current investigation was to explore the lateral stiffness of different sports wheelchair wheels available to athletes in 'new' and 'used' conditions and to determine the effect of (a) stiffness, (b) tyre type (clincher vs. tubular) and (c) tyre orientation on the physiological and biomechanical responses to submaximal and maximal effort propulsion specific to wheelchair basketball. Eight able-bodied individuals participated in the laboratory-based testing, which took place on a wheelchair ergometer at two fixed speeds (1.1 and 2.2 m s(-1)). Outcome measures were power output and physiological demand (oxygen uptake and heart rate). Three participants with experience of over-ground sports wheelchair propulsion also performed 2 × 20 m sprints in each wheel configuration. Results revealed that wheels differed significantly in lateral stiffness with the 'new' Spinergy wheel shown to be the stiffest (678.2 ± 102.1 N mm(-1)). However the effects of stiffness on physiological demand were minimal compared to tyre type whereby tubular tyres significantly reduced the rolling resistance and power output in relation to clincher tyres. Therefore tyre type (and subsequently inflation pressure) remains the most important aspect of wheel specification for athletes to consider and monitor when configuring a sports wheelchair. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

  3. Rock samples from LEP/LHC tunnel excavation

    CERN Multimedia

    1985-01-01

    Rock samples taken from 0 to 170 m below ground on the CERN site when the LEP (Large Electron Positron collider) pit number 6 was drilled in Bois-chatton (Versonnex). The challenges of LHC civil engineering: A mosaic of works, structures and workers of differents crafts and origins. Three consulting consortia for the engineering and the follow-up of the works. Four industrial consortia for doing the job. A young team of 25 CERN staff, 30 surface buildings, 32 caverns of all sizes, 170 000 m3 of concrete, 420 000 m3 excavated. 1998-2004 : six years of work and 340 millions Swiss Francs.

  4. Kirke Hyllinge and Snesere - Romanesque Twin Towers Recently Excavated

    DEFF Research Database (Denmark)

    Rensbro, Henriette; Vedsø, Mogens

    2015-01-01

    Mirator, 2015. Co-author: Mogens Vedsø. Romanesque twin towers in Danish village churches have long tradition of research. Two recent excavations in Kirke Hyllinge and Snesere have revealed archaeological traces of rectangular towers which in this article are compared to other examples from Denmark....... Kirke Hyllinge church is an outstanding example of twin towers due to the length of the west-section of 16 meters. The only parallel is a planned three-aisled village church in the other end of the country. While for Snesere church the main question is the design of the top section, whether...... it was a twin tower or not....

  5. Problems of locomotive wheel wear in fleet replacement

    Directory of Open Access Journals (Sweden)

    L.P. Lingaytis

    2013-08-01

    Full Text Available Purpose. To conduct a research and find out the causes of defects appearing on the wheel thread of freight locomotives 2М62 and SIEMENS ER20CF. Methodology. To find the ways to solve this problem comparing the locomotive designs and their operating conditions. Findings. After examining the nature of the wheel wear the main difference was found: in locomotives of the 2M62 line wears the wheel flange, and in the locomotives SIEMENS ER20CF – the tread surface. After installation on the 2M62 locomotive the lubrication system of flanges their wear rate significantly decreased. On the new freight locomotives SIEMENS ER20CF the flange lubrication systems of the wheel set have been already installed at the factory, however the wheel thread is wearing. As for locomotives 2M62, and on locomotives SIEMENS ER20CF most wear profile skating wheels of the first wheel set. On both locomotive lines the 2М62 and the SIEMENS ER20CF the tread profile of the first wheel set most of all is subject to the wear. After reaching the 170 000 km run, the tread surface of some wheels begins to crumble. There was a suspicion that the reason for crumb formation of the wheel surface may be insufficient or excessive wheel hardness or its chemical composition. In order to confirm or deny this suspicion the following studies were conducted: the examination of the rim surface, the study of the wheel metal hardness and the document analysis of the wheel production and their comparison with the results of wheel hardness measurement. Practical value. The technical condition of locomotives is one of the bases of safety and reliability of the rolling stock. The reduction of the wheel wear significantly reduces the operating costs of railway transport. After study completion it was found that there was no evidence to suggest that the ratio of the wheel-rail hardness could be the cause of the wheel surface crumbling.

  6. Environmental problems caused by Istanbul subway excavation and suggestions for remediation

    Science.gov (United States)

    Ocak, Ibrahim

    2009-10-01

    Many environmental problems caused by subway excavations have inevitably become an important point in city life. These problems can be categorized as transporting and stocking of excavated material, traffic jams, noise, vibrations, piles of dust mud and lack of supplies. Although these problems cause many difficulties, the most pressing for a big city like Istanbul is excavation, since other listed difficulties result from it. Moreover, these problems are environmentally and regionally restricted to the period over which construction projects are underway and disappear when construction is finished. Currently, in Istanbul, there are nine subway construction projects in operation, covering approximately 73 km in length; over 200 km to be constructed in the near future. The amount of material excavated from ongoing construction projects covers approximately 12 million m3. In this study, problems—primarily, the problem with excavation waste (EW)—caused by subway excavation are analyzed and suggestions for remediation are offered.

  7. Discrete element analysis of the excavation effect of cross-river tunnel on the surroundings

    Directory of Open Access Journals (Sweden)

    Liu Dongyuan

    2017-01-01

    Full Text Available Cross-river tunnel as one of the underground constructions is complicated during its construction. For stability of tunnel excavation, it is emergency to analyze the dynamic characteristics of tunnel deformation under high water pressure. Therefore, a cross-river tunnel model is proposed based on DEM in this paper. Stiffness of particles decreases during excavation process which is as one of excavation methods. Porosity ratio of original porosity over its value at different excavation time has been considered. Radial displacements of particles at different angle around the tunnel are detected during excavation process. It shows that large deformation occurs at the vault of the excavation zone which accompanies with large radial displacement. The upper half of the tunnel performs larger deformation than the lower half part which results in many cracks in the concrete lining, the high water pressure may play an crucial role in it.

  8. The colour wheels of art, perception, science and physiology

    Science.gov (United States)

    Harkness, Nick

    2006-06-01

    Colour is not the domain of any one discipline be it art, philosophy, psychology or science. Each discipline has its own colour wheel and this presentation examines the origins and philosophies behind the colour circles of Art, Perception, Science and Physiology (after image) with reference to Aristotle, Robert Boyle, Leonardo da Vinci, Goethe, Ewald Hering and Albert Munsell. The paper analyses and discusses the differences between the four colour wheels using the Natural Colour System® notation as the reference for hue (the position of colours within each of the colour wheels). Examination of the colour wheels shows the dominance of blue in the wheels of art, science and physiology particularly at the expense of green. This paper does not consider the three-dimensionality of colour space its goal was to review the hue of a colour with regard to its position on the respective colour wheels.

  9. Food offerings, flowers, a bronze bucket and a waggon: a multidisciplinary approach regarding the Hallstatt princely grave from Prague-Letňany, Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Kozáková, Radka; Kyselý, René; Trefný, M.; Drábková, K.; Kočár, Petr; Frolíková, Drahomíra; Kočárová, R.; Moravcová, Kamila

    -, - (2017) ISSN 1866-9557 Institutional support: RVO:67985912 Keywords : grave * meat offerings * pollen * bronze bucket * paint * infrared spectroscopy * xylotomic analysis Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 1.844, year: 2016

  10. Evaluation of bending moment and deflection of cantilever supported excavations

    Directory of Open Access Journals (Sweden)

    Seyed Hamid Yasrebi

    2017-11-01

    Full Text Available In many conditions, because of several restrictions, cantilever walls are the only way to stabilize the excavations. It is no doubt that one of the most important parameters in design of such walls is wall stiffness. Therefore, in this study, a large number of case histories are collected and the most commonly used range of wall thickness and stiffness are determined based on this database. In addition, validation of limit equilibrium method (LEM in granular soils showed that this method can only estimate bending moment of rigid walls. Therefore, for more accurate estimating, a new equation is presented for the most commonly used range of wall stiffness and various types of granular soils. Moreover, LEM based equation is replaced with a modified version. The new equation was successfully validated using 70 numerical models and results lied in range of 85% to 115% times the predicted values obtained from FEM. According to the results, in loose and very loose soils, the common cantilever walls can only stabilize the excavations with depth less than 10 m. While if depth is more than 15 m, soil type should be dense or very dense with “E” more than about 70 MPa. The results also show that the effect of wall stiffness is negligible in bending moments less than 2000 kN.m.

  11. Target and Projectile: Material Effects on Crater Excavation and Growth

    Science.gov (United States)

    Anderson, J. L. B.; Burleson, T.; Cintala, Mark J.

    2010-01-01

    Scaling relationships allow the initial conditions of an impact to be related to the excavation flow and final crater size and have proven useful in understanding the various processes that lead to the formation of a planetary-scale crater. In addition, they can be examined and tested through laboratory experiments in which the initial conditions of the impact are known and ejecta kinematics and final crater morphometry are measured directly. Current scaling relationships are based on a point-source assumption and treat the target material as a continuous medium; however, in planetary-scale impacts, this may not always be the case. Fragments buried in a megaregolith, for instance, could easily approach or exceed the dimensions of the impactor; rubble-pile asteroids could present similar, if not greater, structural complexity. Experiments allow exploration into the effects of target material properties and projectile deformation style on crater excavation and dimensions. This contribution examines two of these properties: (1) the deformation style of the projectile, ductile (aluminum) or brittle (soda-lime glass) and (2) the grain size of the target material, 0.5-1 mm vs. 1-3 mm sand.

  12. Reduction of excavation face collapse risk in tunnelling.

    Science.gov (United States)

    Ariani, Filippo; Baldasseroni, Alberto; Muller, Alessandro; Biffino, Marco; Matteucci, Alessandro

    2017-12-14

    Two large road tunnels, recently developed near Florence, showed instabilities of the excavation face which subsequently caused sixteen collapses. Due to the risk for workers' safety, the public authority for occupational health and safety (ASL) has monitored the failure rate and other background variables in order to assess the possible correlations between risk reductions, its own actions, and those of the various safety actors involved. To evaluate if the interventions carried out by the design team were able to reduce the risks of collapse and which of the ASL actions and/or which other factors were more effective in changing the attitudes of the parties involved, leading to a more expensive but safer project variant. After adoption of the second of two project variants, no more collapses were observed. No correlation was found between trend of ASL inspections and observed variation of collapse rate. Conversely, the adoption of strongly coercive measures and investigation reporting by local media coincided with periods of risk reduction, even if the low number of events does not allow for statistical evaluation. These findings appear to be coherent with the ratio of the cost of penalties related to health and safety infringements (thousands of euros) to the overall cost of the safer project variant (a hundred times greater).  The safer variant required 7% more labour but avoided forced interruptions caused by the collapses, allowing a 13% faster excavation rate.

  13. Evaluation of excavation experience: Pierre shale. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Abel, J.F. Jr.; Gentry, D.W.

    1975-06-27

    Pierre shale and its stratigraphic equivalents represent a potentially favorable geologic environment for underground storage of hazardous waste products. These rock formations cover great areal and vertical extents, and represent some of the least permeable rock formations within the continental United States. There are, however, several engineering problems associated with constructing underground openings in Pierre shale. This formation is relatively weak and tends to deteriorate rather rapidly if not protected from the mine environment. It will be necessary to place all underground openings below the surficially weathered upper 50 to 70 feet of Pierre shale which contains groundwater moving on fracture permeability. The optimum site for disposal of hazardous waste in Pierre shale, or its stratigraphic equivalents, would be a seismically stable platform bounded on all sides by faults. The optimum size of individual openings would be the minimum necessary for access, storage, and retrieval of waste components. Underground excavations in Pierre shale must be made with care, must be of limited dimensions, must be widely spaced, must be protected from prolonged contact with the mine environment, must be supported immediately after excavation, and must be sited to avoid areas of faulting and(or) intense jointing. Underground openings constructed with boring machines and supported with wet shotcrete are recommended.

  14. From Excavations to Web: a GIS for Archaeology

    Science.gov (United States)

    D'Urso, M. G.; Corsi, E.; Nemeti, S.; Germani, M.

    2017-05-01

    The study and the protection of Cultural Heritage in recent years have undergone a revolution about the search tools and the reference disciplines. The technological approach to the problem of the collection, organization and publication of archaeological data using GIS software has completely changed the essence of the traditional methods of investigation, paving the way to the development of several application areas, up to the Cultural Resource Management. A relatively recent specific sector of development for archaeological GIS development sector is dedicated to the intra - site analyses aimed to recording, processing and display information obtained during the excavations. The case - study of the archaeological site located in the south - east of San Pietro Vetere plateau in Aquino, in the Southern Lazio, is concerned with the illustration of a procedure describing the complete digital workflow relative to an intra-site analysis of an archaeological dig. The GIS project implementation and its publication on the web, thanks to several softwares, particularly the FOSS (Free Open Source Software) Quantum - GIS, are an opportunity to reflect on the strengths and the critical nature of this particular application of the GIS technology. For future developments in research it is of fundamental importance the identification of a digital protocol for processing of excavations (from the acquisition, cataloguing, up data insertion), also on account of a possible future Open Project on medieval Aquino.

  15. A CASE OF FULL-THICKNESS MACULAR HOLE IN EYE WITH FOCAL CHOROIDAL EXCAVATION.

    Science.gov (United States)

    Fayyad, Omar Faisal; Al-Hashimi, Mustafa Raad; Fayyad, Faisal Tawfeeq

    2016-12-09

    To report an association between a Stage 4 full-thickness macular hole and focal choroidal excavation. Case report. A 46-year-old male patient with high myopia was referred for macular hole surgery and found to have an associated focal choroidal excavation. The patient underwent uneventful combined procedure with closure of macular hole. Successful macular hole surgery can be achieved even in the presence of focal choroidal excavation.

  16. Analysis of traversable pits model to make intelligent wheeled vehicles

    Directory of Open Access Journals (Sweden)

    F. Abbasi

    2017-11-01

    Full Text Available In this paper, the issue of passing wheeled vehicles from pits is discussed. The issue is modeled by defining the limits of passing wheeled vehicles. The proposed model has been studied based on changes in the effective parameters. Finally, in order to describe the problem, the proposed model has been solved for wheeled vehicles based on the effective parameters by using one of the numerical methods.

  17. Developement of Vibrodiagnostic System of Tram Wheel for Damage Analysis

    OpenAIRE

    Pešek, Luděk; Vaněk, František; Balda, Miroslav; Procházka, Pavel; Vaněk, Petr; Cibulka, Jan; Bula, Vítězslav

    2008-01-01

    The vibrodiagnostic system VDS-UT2 was developed for the investigation of a tram wheel operational vibration and deformation. The system consists of measuring, acquisition and processing tools for monitoring of tram wheels and their operational parameters, e.g. static and dynamic deformation, displacement, velocity, acceleration and temperature. The measuring on a rotating wheel is realized both by telemetric and by top-timing system. Measured data can be remote-observed via Internet connecti...

  18. Wheel Rail Lateral Impact and Derailment Safety Assessment

    Science.gov (United States)

    Guan, Qinghua; Zeng, Jing

    It is known to all that derailment is the vital problem in railway transportation. As the increase of vehicle speed, the possibility of derailment due to the lateral impact between the wheel flange and the rail increases. An impact model for the impact between the wheel and rail together with an accurate kinematic analysis is presented in order to shed some light on the wheel lift derailment of high-speed vehicles.

  19. Parameterization of a bucket model for soil-vegetation-atmosphere modeling under seasonal climatic regimes

    Directory of Open Access Journals (Sweden)

    N. Romano

    2011-12-01

    Full Text Available We investigate the potential impact of accounting for seasonal variations in the climatic forcing and using different methods to parameterize the soil water content at field capacity on the water balance components computed by a bucket model (BM. The single-layer BM of Guswa et al. (2002 is employed, whereas the Richards equation (RE based Soil Water Atmosphere Plant (SWAP model is used as a benchmark model. The results are analyzed for two differently-textured soils and for some synthetic runs under real-like seasonal weather conditions, using stochastically-generated daily rainfall data for a period of 100 years. Since transient soil-moisture dynamics and climatic seasonality play a key role in certain zones of the World, such as in Mediterranean land areas, a specific feature of this study is to test the prediction capability of the bucket model under a condition where seasonal variations in rainfall are not in phase with the variations in plant transpiration. Reference is made to a hydrologic year in which we have a rainy period (starting 1 November and lasting 151 days where vegetation is basically assumed in a dormant stage, followed by a drier and rainless period with a vegetation regrowth phase. Better agreement between BM and RE-SWAP intercomparison results are obtained when BM is parameterized by a field capacity value determined through the drainage method proposed by Romano and Santini (2002. Depending on the vegetation regrowth or dormant seasons, rainfall variability within a season results in transpiration regimes and soil moisture fluctuations with distinctive features. During the vegetation regrowth season, transpiration exerts a key control on soil water budget with respect to rainfall. During the dormant season of vegetation, the precipitation regime becomes an important climate forcing. Simulations also highlight the occurrence of bimodality in the probability distribution of soil moisture during the season when plants are

  20. [The "Ice Bucket Challenge": wondering about the impact of social networks to promote public health interventions].

    Science.gov (United States)

    Gualano, Maria Rosaria; Bert, Fabrizio; Gili, Renata; Andriolo, Violetta; Scaioli, Giacomo; Siliquini, Roberta

    2015-01-01

    The "Ice Bucket Challenge" was an activity launched to promote awareness of amyotrophic lateral sclerosis (ALS) and encourage donations to research for this disease. The campaign went viral on social media during July to August 2014. It consisted in nominating people and challenging them to donate 100 dollars to the ALS Association or pour a bucket of ice water over their head and post the video on the web. Participants in turn then had to challenge others to do the same. The initiative was hugely successful, involved millions of people and, just in the US, collected 35 times more money than in the same time period in 2013. We analyzed possible factors that determined the success of this initiative, to identify strengths and weaknesses of the activity and evaluate the possibility of applying the same model to promote public health interventions. Several features of the challenge were identified as strengths: the involvement of wellknown people from different contexts, the "public platform" which triggers a positive combination of competitiveness, social pressure and narcissism, the chain-letter like method of nomination, the ironic and entertaining nature of the performance. Besides these strengths, weaknesses were also identified: information spread via social media can only partially reach potential donors and supporters, due to the digital divide phenomenon which excludes people who do not have web access. Also, it is not possible to predict if the message will be long-lasting or will cease shortly after the end of the campaign. The latter could be acceptable for fund-raising, where the aim is simply to collect as much money as possible, but not for a public health intervention program, whose success requires that the intended message has a long-lasting effect to produce an effective change in people's behavior. Despite the above-mentioned limits, social networks undeniably show great potential to spread messages to the community and to involve a large number of

  1. Parametric Optimization and Prediction Tool for Excavation and Prospecting Tasks Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Honeybee Robotics therefore proposed to develop a software tool for facilitating prospecting and excavation system trades in support of selecting an optimal...

  2. The bucket and the searchlight: formulating and testing risk hypotheses about the weediness and invasiveness potential of transgenic crops.

    Science.gov (United States)

    Raybould, Alan

    2010-01-01

    The bucket and the searchlight are metaphors for opposing theories of the growth of scientific knowledge. The bucket theory proposes that knowledge is gained by observing the world without preconceptions, and that knowledge emerges from the accumulation of observations that support a hypothesis. There are many problems with this theory, the most serious of which is that it does not appear to offer a means to distinguish between the many hypotheses that could explain a particular set of observations. The searchlight theory proposes that preconceptions are unavoidable and that knowledge advances through the improvement of our preconceptions - our hypotheses - by continuous criticism and revision. A hypothesis is a searchlight that illuminates observations that test the hypothesis and reveal its flaws, and knowledge thereby increases through the elimination of false hypotheses. Research into the risks posed by the cultivation of transgenic crops often appears to apply the bucket theory; many data are produced, but knowledge of risk is not advanced. Application of the searchlight theory, whereby risk assessments test hypotheses that transgenic crops will not be harmful, seems to offer a better way to characterise risk. The effectiveness of an environmental risk assessment should not be measured by the size of the bucket of observations on a transgenic crop, but by the power of the risk hypothesis searchlights to clarify the risks that may arise from cultivation of that crop. These points are illustrated by examples of hypotheses that could be tested to assess the risks from transgenic crops and their hybrids becoming weeds or invading non-agricultural habitats. © ISBR, EDP Sciences, 2011.

  3. Wheel traffic effect on air-filled porosity and air permeability in a soil catena across the wheel rut

    DEFF Research Database (Denmark)

    Berisso, Feto Esimo; Schjønning, Per; Lamandé, Mathieu

    The impact of wheel traffic on soil physical properties is usually quantified by randomly collecting soil cores at specific depths below the wheeled surface. However, modeling studies as well as few measurements indicated a non-uniform stress distribution in a catena across the wheel rut, which...... might induce different effects on soil physical properties. The objective of this study was to investigate the impact of vehicle traffic on soil physical properties and air permeability by systematic collection of samples in a transect running from the center to the outside of the wheel rut. A field...... experiment was conducted on a clay loam soil at Suberg, Switzerland, in 2010. Four repeated wheeling were performed by driving a forage harvester (wheel load of 6100 kg and a tyre width of 0.8 m) forward and rearward in the same track. We sampled 100 cm3 intact cores at 10, 30 and 50 cm depth in a soil...

  4. Delta FosB regulates wheel running.

    Science.gov (United States)

    Werme, Martin; Messer, Chad; Olson, Lars; Gilden, Lauren; Thorén, Peter; Nestler, Eric J; Brené, Stefan

    2002-09-15

    DeltaFosB is a transcription factor that accumulates in a region-specific manner in the brain after chronic perturbations. For example, repeated administration of drugs of abuse increases levels of DeltaFosB in the striatum. In the present study, we analyzed the effect of spontaneous wheel running, as a model for a natural rewarding behavior, on levels of DeltaFosB in striatal regions. Moreover, mice that inducibly overexpress DeltaFosB in specific subpopulations of striatal neurons were used to study the possible role of DeltaFosB on running behavior. Lewis rats given ad libitum access to running wheels for 30 d covered what would correspond to approximately 10 km/d and showed increased levels of DeltaFosB in the nucleus accumbens compared with rats exposed to locked running wheels. Mice that overexpress DeltaFosB selectively in striatal dynorphin-containing neurons increased their daily running compared with control littermates, whereas mice that overexpress DeltaFosB predominantly in striatal enkephalin-containing neurons ran considerably less than controls. Data from the present study demonstrate that like drugs of abuse, voluntary running increases levels of DeltaFosB in brain reward pathways. Furthermore, overexpression of DeltaFosB in a distinct striatal output neuronal population increases running behavior. Because previous work has shown that DeltaFosB overexpression within this same neuronal population increases the rewarding properties of drugs of abuse, results of the present study suggest that DeltaFosB may play a key role in controlling both natural and drug-induced reward.

  5. Influence of wheel configuration on wheelchair basketball performance : Wheel stiffness, tyre type and tyre orientation

    NARCIS (Netherlands)

    Mason, B. S.; Lemstra, M.; van der Woude, L. H. V.; Vegter, R.; Goosey-Tolfrey, V. L.

    The aim of the current investigation was to explore the lateral stiffness of different sports wheelchair wheels available to athletes in 'new' and 'used' conditions and to determine the effect of (a) stiffness, (b) tyre type (clincher vs. tubular) and (c) tyre orientation on the physiological and

  6. The Drag of Airplane Wheels, Wheel Fairings and Landing Gears-I

    Science.gov (United States)

    1934-01-01

    thle tire 12 (’(lull have a1 eobivetitiotilll’(leo strilt but t~it( whell ’’ diameter (8.54-10) wheel and time) .fairitor E conlsists %Vliiid swvingll...appreciably at high speeds. of wings as well as the wing areas may affect the re- suilts somewhat, it is believed that the wings selected CONCLUSIONS will

  7. Fabrication of gas turbine water-cooled composite nozzle and bucket hardware employing plasma spray process

    Science.gov (United States)

    Schilke, Peter W.; Muth, Myron C.; Schilling, William F.; Rairden, III, John R.

    1983-01-01

    In the method for fabrication of water-cooled composite nozzle and bucket hardware for high temperature gas turbines, a high thermal conductivity copper alloy is applied, employing a high velocity/low pressure (HV/LP) plasma arc spraying process, to an assembly comprising a structural framework of copper alloy or a nickel-based super alloy, or combination of the two, and overlying cooling tubes. The copper alloy is plamsa sprayed to a coating thickness sufficient to completely cover the cooling tubes, and to allow for machining back of the copper alloy to create a smooth surface having a thickness of from 0.010 inch (0.254 mm) to 0.150 inch (3.18 mm) or more. The layer of copper applied by the plasma spraying has no continuous porosity, and advantageously may readily be employed to sustain a pressure differential during hot isostatic pressing (HIP) bonding of the overall structure to enhance bonding by solid state diffusion between the component parts of the structure.

  8. Drowsy Driver Detection via Steering Wheel

    Directory of Open Access Journals (Sweden)

    Herlina ABDUL RAHIM

    2010-09-01

    Full Text Available The main purpose of this project is to produce a safety system especially for fatigue car driver so as to prevent from accidents. The statistic on road fatality shows that human error constitute of 64.84 % road accidents fatality and 17.4 % due to technical factors. These systems encompassed the approach of hand pressure applied on the steering wheel. The steering will be installed with pressure sensors. At the same time these sensors can be used to measure gripping force while driving.

  9. Innovative stair climber using associated wheels

    Science.gov (United States)

    Modak, Girish Sudhir; Bhoomkar, Manmohan Manikrao

    2016-09-01

    The study proposes an innovative and completely new but low-cost configuration of a platform that can easily climb stairs. This platform serves the purpose of a chassis. Different versions, such as staircase-climbing wheelchair or staircase-climbing trolley for material transferring, can be derived depending on the structure built on the platform. The driving wheels have a shape that completely matches with the profile of the steps. Complex components are eliminated. Thus, this platform is conveniently applicable in the configurations useful for climbing staircases.

  10. Shaft Excavation in Frozen Ground at Point 5

    CERN Document Server

    Osborne, J

    2000-01-01

    Construction work on the 112 MCHF civil engineering contract started at Point 5 in August 1998. The new surface buildings and underground structures are necessary to accommodate the CMS detector for the LHC Project. The principal underground works consist of two new shafts, two parallel caverns separated by a supporting pillar, and a number of small connection tunnels and service galleries. The two shafts are to be sunk through approximately 50 m of water-bearing moraine to the underlying molasse rock. From a number of possible construction methods, ground freezing of the moraine was considered to be most appropriate. The ground freezing is used to control the groundwater and to support temporarily the moraine during excavation and lining of the shafts. The aim of this paper is to present the ground-freezing technique and to discuss the advantages and disadvantages of the system in the light of its first few months of running on the Point 5 site.

  11. Groundwater flow modelling of the excavation and operational phases - Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Urban (Computer-aided Fluid Engineering AB, Lyckeby (Sweden)); Rhen, Ingvar (SWECO Environment AB, Falun (Sweden))

    2010-12-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. The modelling study reported here presents calculated inflow rates, drawdown of the groundwater table and upconing of deep saline water for different levels of grouting efficiency during the excavation and operational phases of a final repository at Laxemar. The inflow calculations were accompanied by a sensitivity study, which among other matters handled the impact of different deposition hole rejection criteria. The report also presents tentative modelling results for the duration of the saturation phase, which starts once the used parts of the repository are being backfilled

  12. Theoretical study of short pile effect in tunnel excavation

    Science.gov (United States)

    Tian, Xiao-yan; Liu, Jing; Gao, Xiao-mei; Li, Yuan

    2017-09-01

    The Misaki Sato Go ideal elastoplastic model is adopted and the two stage analysis theory is used to study the effect of tunnel excavation on short pile effect in this paper. In the first stage, the free field vertical displacement of the soil at the corresponding pile location is obtained by using empirical formula. In the second stage, the displacement is applied to the corresponding pile location. The equilibrium condition of micro physical differential equation settlement of piles. Then through logical deduction and the boundary condition expressions of the settlement calculation, obtain the pile side friction resistance and axial force of the week. Finally, an engineering example is used to analyze the influence of the change of main parameters on their effects.

  13. Stability assessment for underground excavations and key construction techniques

    CERN Document Server

    Zhu, Hanhua; Zhao, Yu; Niu, Fusheng

    2017-01-01

    This book examines how the state of underground structures can be determined with the assistance of force, deformation and energy. It then analyzes mechanized shield methods, the New Austrian tunneling method (NATM) and conventional methods from this new perspective. The book gathers a wealth of cases reflecting the experiences of practitioners and administrators alike. Based on statistical and engineering studies of these cases, as well as lab and field experiments, it develops a stability assessment approach incorporating a stable equilibrium, which enables engineers to keep the structure and surrounding rocks safe as long as the stable equilibrium and deformation compliance are maintained. The book illustrates the implementation of the method in various tunneling contexts, including soil-rock mixed strata, tunneling beneath operating roads, underwater tunnels, and tunnel pit excavation. It offers a valuable guide for researchers, designers and engineers, especially those who are seeking to understand the u...

  14. Pajarito Plateau archaeological survey and excavations. [Los Alamos Reservation

    Energy Technology Data Exchange (ETDEWEB)

    Steen, C.R.

    1977-05-01

    Los Alamos Scientific Laboratory lands were surveyed to locate pre-Columbian Indian ruins. The survey results will permit future construction to be planned so that most of the ancient sites in the area can be preserved. Indian occupation of the area occurred principally from late Pueblo III times (late 13th century) until early Pueblo V (about the middle of the 16th century). There are evidences of sporadic Indian use of the area for some 10,000 years. One Folsom point has been found, as well as many other archaic varieties of projectile points. Continued use of the region well into the historic period is indicated by pictographic art that portrays horses. In addition to an account of the survey, the report contains summaries of excavations made on Laboratory lands between 1950 and 1975.

  15. The Application of Foundation Pit Monitoring Technology to the Excavation

    Directory of Open Access Journals (Sweden)

    Qiu Jin

    2015-01-01

    Full Text Available The foundation pit monitoring plays an important role in the foundation pit supporting projects especially in those deep foundation pit projects. Through the whole monitoring of the foundation pit construction from the excavation to the backfill, we can learn about the forcing and deforming process of the foundation pit supporting system, and grasp the impact of external condition changes on the foundation pit. This paper takes a project in Jinan as an example to establish a specific monitoring program, and then conducts the analysis and evaluation of the monitoring data; the real-time grasp of the foundation pit deformation and internal force changes can help to further ensure the security status of the foundation pit, thus better guiding the construction.

  16. THE EXPANDING CLINICAL SPECTRUM OF CHOROIDAL EXCAVATION IN MACULAR DYSTROPHIES.

    Science.gov (United States)

    Battaglia Parodi, Maurizio; Casalino, Giuseppe; Iacono, Pierluigi; Introini, Ugo; Adamyan, Tatevik; Bandello, Francesco

    2017-08-09

    To assess the prevalence and the clinical course of focal choroidal excavation (FCE) in patients affected by macular dystrophies. Prospective case series. All the patients underwent a complete ophthalmologic examination, including best-corrected visual acuity and spectral domain optical coherence tomography. The presence of choroidal neovascularization (CNV) was assessed on the basis of the leakage detected on fluorescein angiography. A total of 162 eyes from 81 patients with macular dystrophy were included in the study. FCE was diagnosed in seven eyes (4.3% of the eyes), including four eyes with Best vitelliform dystrophy, two eyes with pattern dystrophy associated with pseudoxanthoma elasticum, and one case of Stargardt disease. In eyes with FCE and macular dystrophy, the mean best-corrected visual acuity was 0.4 ± 0.1 logarithm of the minimum angle of resolution (approximately corresponding to 20/50 Snellen equivalent) at baseline and was stable to 0.41 ± 0.1 logarithm of the minimum angle of resolution (approximately corresponding to 20/50 Snellen equivalent) at the final visit. In four of these seven eyes, FCE was associated with a subfoveal CNV. The CNV was managed with one intravitreal anti-vascular endothelial growth factor injection, achieving the complete anatomical stabilization of the CNV and recovery of the best-corrected visual acuity. Focal choroidal excavation can be infrequently encountered in patients with macular dystrophies. The presence of CNV may complicate FCE in these patients, and anti-vascular endothelial growth factor seems to be an effective treatment with no progression of FCE over time.

  17. Full-face excavation of large tunnels in difficult conditions

    Directory of Open Access Journals (Sweden)

    Giovanni Barla

    2016-06-01

    Full Text Available Following a few preliminary remarks on the tunneling methods at the beginning of the 20th century, the successful applications of the full-face method also in difficult conditions are underlined. The attention is posed on the use of a systematic reinforcement of the face and of the ground, by means of fiber-glass elements. A selection of tunnels where this method was used successfully is reported with the purpose of illustrating the wide spectrum of ground conditions where it has been applied. Then, following a description of the main concepts behind the method, the attention moves from the so-called “heavy method”, where deformations are restrained, to the “light method”, where deformations are allowed with the intention to decrease the stresses acting on the primary and final linings. The progress in the application of the “light method” is underlined, up to the development of a novel technique, which relies on the use of a yielding support composed of top head steel sets with sliding joints and special deformable elements inserted in the primary lining. The well-known case study of the Saint Martin La Porte access adit, along the Lyon-Turin Base Tunnel, is described. In this tunnel, a yield-control support system combined with full-face excavation has been adopted successfully in order to cope with the large deformations experienced during face advance through the Carboniferous formation. The monitoring results obtained during excavation are illustrated, together with the modeling studies performed when paying attention to the rock mass time-dependent behavior.

  18. Longitudinal wheel slip during ABS braking

    Science.gov (United States)

    Hartikainen, Lassi; Petry, Frank; Westermann, Stephan

    2015-02-01

    Anti-lock braking system (ABS) braking tests with two subcompact passenger cars were performed on dry and wet asphalt, as well as on snow and ice surfaces. The operating conditions of the tyres in terms of wheel slip were evaluated using histograms of the wheel slip data. The results showed different average slip levels for different road surfaces. It was also found that changes in the tyre tread stiffness affected the slip operating range through a modification of the slip value at which the maximum longitudinal force is achieved. Variation of the tyre footprint length through modifications in the inflation pressure affected the slip operating range as well. Differences in the slip distribution between vehicles with different brake controllers were also observed. The changes in slip operating range in turn modified the relative local sliding speeds between the tyre and the road. The results highlight the importance of the ABS controller's ability to adapt to changing slip-force characteristics of tyres and provide estimates of the magnitude of the effects of different tyre and road operating conditions.

  19. Camber Angle Inspection for Vehicle Wheel Alignments

    Directory of Open Access Journals (Sweden)

    Jieh-Shian Young

    2017-02-01

    Full Text Available This paper introduces an alternative approach to the camber angle measurement for vehicle wheel alignment. Instead of current commercial approaches that apply computation vision techniques, this study aims at realizing a micro-control-unit (MCU-based camber inspection system with a 3-axis accelerometer. We analyze the precision of the inspection system for the axis misalignments of the accelerometer. The results show that the axes of the accelerometer can be aligned to the axes of the camber inspection system imperfectly. The calibrations that can amend these axis misalignments between the camber inspection system and the accelerometer are also originally proposed since misalignments will usually happen in fabrications of the inspection systems. During camber angle measurements, the x-axis or z-axis of the camber inspection system and the wheel need not be perfectly aligned in the proposed approach. We accomplished two typical authentic camber angle measurements. The results show that the proposed approach is applicable with a precision of ± 0.015 ∘ and therefore facilitates the camber measurement process without downgrading the precision by employing an appropriate 3-axis accelerometer. In addition, the measured results of camber angles can be transmitted via the medium such as RS232, Bluetooth, and Wi-Fi.

  20. New Small Wheel Technical Design Report

    CERN Document Server

    AUTHOR|(CDS)2071368; Pontecorvo, L; Dubbert, J; Mikenberg, G; Iengo, P; Dallapiccola, C; Amelung, C; Levinson, L; Richter, R; Lellouch, D; CERN. Geneva. The LHC experiments Committee; LHCC

    2013-01-01

    In order to benefit from the expected high luminosity performance that will be provided by the Phase-I upgraded LHC, the first station of the ATLAS muon end-cap system (Small Wheel,SW) will need to be replaced. The New Small Wheel (NSW) will have to operate in a high background radiation region (up to 15 kHz=cm2) while reconstructing muon tracks with high precision, as well as furnishing information for the Level-1 trigger. These performance criteria are demanding. In particular, the precision reconstruction of tracks for offline analysis requires a spatial resolution of about 100microns, and the Level-1 trigger track segments have to be reconstructed online with an angular resolution of approximately 1mrad. The NSW will have two chamber technologies, one primarily devoted to the Level-1 trigger function (small-strip Thin Gap Chambers, sTGC) and one dedicated to precision tracking (Micromegas detectors, MM). The sTGC are primarily deployed for triggering given their single bunch crossing identification capabi...

  1. Simulation of Intelligent Single Wheel Mobile Robot

    Directory of Open Access Journals (Sweden)

    Maki K. Rashid

    2008-11-01

    Full Text Available Stabilization of a single wheel mobile robot attracted researcher attentions in robotic area. However, the budget requirements for building experimental setups capable in investigating isolated parameters and implementing others encouraged the development of new simulation methods and techniques that beat such limitations. In this work we have developed a simulation platform for testing different control tactics to stabilize a single wheel mobile robot. The graphic representation of the robot, the dynamic solution, and, the control scheme are all integrated on common computer platform using Visual Basic. Simulation indicates that we can control such robot without knowing the detail of it's internal structure or dynamics behaviour just by looking at it and using manual operation tactics. Twenty five rules are extracted and implemented using Takagi-Sugeno's fuzzy controller with significant achievement in controlling robot motion during the dynamic simulation. The resulted data from the successful implementation of the fuzzy model are used to utilize and train a neurofuzzy controller using ANFIS scheme to produce further improvement in robot performance

  2. Simulation of Intelligent Single Wheel Mobile Robot

    Directory of Open Access Journals (Sweden)

    Maki K. Rashid

    2007-03-01

    Full Text Available Stabilization of a single wheel mobile robot attracted researcher attentions in robotic area. However, the budget requirements for building experimental setups capable in investigating isolated parameters and implementing others encouraged the development of new simulation methods and techniques that beat such limitations. In this work we have developed a simulation platform for testing different control tactics to stabilize a single wheel mobile robot. The graphic representation of the robot, the dynamic solution, and, the control scheme are all integrated on common computer platform using Visual Basic. Simulation indicates that we can control such robot without knowing the detail of it's internal structure or dynamics behaviour just by looking at it and using manual operation tactics. Twenty five rules are extracted and implemented using Takagi-Sugeno's fuzzy controller with significant achievement in controlling robot motion during the dynamic simulation. The resulted data from the successful implementation of the fuzzy model are used to utilize and train a neurofuzzy controller using ANFIS scheme to produce further improvement in robot performance

  3. Possibilities of using welding-on technologies in crane wheel ...

    Indian Academy of Sciences (India)

    WINTEC

    Abstract. The paper deals with analysis of welds-on quality of traverse crane wheels made from gr. 90–60 mate- rial, ASTM A148. Three types of welding-on technology with various filling materials were used. On wheel after wearing was welded-on one interlayer by a combination of additional materials, wire A 106 with F 11 ...

  4. The Botswana Medical Eligibility Criteria Wheel: Adapting a Tool to ...

    African Journals Online (AJOL)

    AJRH Managing Editor

    adaptation of the Medical eligibility criteria for contraceptive use (MEC) wheel. The main objectives of this process were to ... and to adapt the MEC wheel to meet the needs of the Botswanian people. This commentary focuses on the .... use among sexually active men and women aged. 15–49 years4. The stakeholders ...

  5. Wheelchair users' perceptions of and experiences with power assist wheels.

    Science.gov (United States)

    Giacobbi, Peter R; Levy, Charles E; Dietrich, Frederick D; Winkler, Sandra Hubbard; Tillman, Mark D; Chow, John W

    2010-03-01

    To assess wheelchair users' perceptions of and experiences with power assist wheels using qualitative interview methods. Qualitative evaluations were conducted in a laboratory setting with a focus on users' experiences using power assist wheel in their naturalistic environments. Participants consisted of seven women and 13 men (M(age) = 42.75, SD = 14.68) that included one African American, one Hispanic, 17 whites, and one individual from Zambia. Qualitative interviews were conducted before, during, and after use of a power assist wheel. Main outcome measures included the wheelchair users' evaluations and experiences related to the use of power assist wheels. The primary evaluations included wheeling on challenging terrains, performance of novel activities, social/family aspects, fatigue, and pain. These descriptions indicated that most participants perceived positive experiences with the power assist wheels, including access to new and different activities. Secondary evaluations indicated that the unit was cumbersome and prohibitive for some participants because of difficulties with transport in and out of a vehicle and battery life. Most participants felt that power assist wheels provided more independence and social opportunities. The power assist wheel seems to offer physical and social benefits for most wheelers. Clinicians should consider users' home environment and overall life circumstances before prescribing.

  6. Low Adhesion in the Wheel-Rail Contact

    NARCIS (Netherlands)

    Arias-Cuevas, O.

    2010-01-01

    Adhesion, or adhesion coefficient, is given by the ratio of the longitudinal tangential (i.e., braking or traction) force over the normal force at the wheel-rail contact. The tangential force that a braking or tractive railway wheel can exert on a rail is limited by the friction coefficient

  7. Research on Walking Wheel Slippage Control of Live Inspection Robot

    Science.gov (United States)

    Yan, Yu; Liu, Xiaqing; Guo, Hao; Li, Jinliang; Liu, Lanlan

    2017-07-01

    To solve the problem of walking wheel slippage of a live inspection robot during walking or climbing, this paper analyzes the climbing capacity of the robot with a statics method, designs a pressing wheel mechanism, and presents a method of indirectly identifying walking wheel slippage by reading speed of the pressing wheel due to the fact that the linear speed of the pressing wheel and the walking wheel at the contract point is the same; and finds that the slippage state can not be controlled through accurate mathematical models after identifying the slippage state, whereas slippage can be controlled with fuzzy control. The experiment results indicate that due to design of the pressing wheel mechanism, friction force of the walking wheel is increased, and the climbing capability of the robot is improved. Within the range of climbing capability of the robot, gradient is the key factor that has influence on slippage of robot, and slippage can be effectively eliminated through the fuzzy control method proposed in this paper.

  8. First Wheel of the Hadronic EndCap Calorimeter Completed

    CERN Document Server

    Oram, C.J.

    2002-01-01

    With the LAr calorimeters well advanced in module production, the attention is turning to Batiment 180 where the calorimeter modules are formed into complete detectors and inserted into their respective cryostats. For the Hadronic End Cap (HEC) Group the task in B180 is to assemble the wheels, rotate them into their final orientation, and put them onto the cradle in front of the End Cap Cryostat. These tasks have been completed for the first HEC wheel in the B180 End Cap Clean Room. Given that this wheel weighs 70 tons the group is very relieved to have established that these gymnastics with the wheel proceed in a routine fashion. To assemble a wheel we take modules that have already been cold tested, do the final electrical testing and locate them onto the HEC wheel assembly table. Four wheels are required in total, each consisting of 32 modules. Wheel assembly is done in the horizontal position, creating a doughnut-like object sitting on the HEC table. The first picture shows the last module being added ...

  9. Dynamics of Railway Vehicles and Rail/Wheel Contact

    DEFF Research Database (Denmark)

    True, Hans

    2007-01-01

    In these notes the fundamentals of the mechanics of rail/wheel contact and deterministic vehicle dynamics is explained. Chapter 1 describes the kinematics and dynamics of rail/wheel contact. Chapter 2 explains why vehicle dynamics must be treated as a nonlinear dynamic problem and how the model...

  10. Considering the Influence of Prerequisite Performance on Wheel Spinning

    Science.gov (United States)

    Wan, Hao; Beck, Joseph Barbosa

    2015-01-01

    The phenomenon of wheel spinning refers to students attempting to solve problems on a particular skill, but becoming stuck due to an inability to learn the skill. Past research has found that students who do not master a skill quickly tend not to master it at all. One question is why do students wheel spin? A plausible hypothesis is that students…

  11. Procedure and applications of combined wheel/rail roughness measurement

    NARCIS (Netherlands)

    Dittrich, M.G.

    2009-01-01

    Wheel-rail roughness is known to be the main excitation source of railway rolling noise. Besides the already standardised method for direct roughness measurement, it is also possible to measure combined wheel-rail roughness from vertical railhead vibration during a train pass-by. This is a different

  12. Hybrid Control Design for a Wheeled Mobile Robot

    DEFF Research Database (Denmark)

    Bak, Thomas; Bendtsen, Jan Dimon; Ravn, Anders Peter

    We present a hybrid systems solution to the problem of trajectory tracking for a four-wheel steered four-wheel driven mobile robot. The robot is modelled as a non-holonomic dynamic system subject to pure rolling, no-slip constraints. Under normal driving conditions, a nonlinear trajectory tracking...

  13. Hybrid Control Design for a Wheeled Mobile Robot

    DEFF Research Database (Denmark)

    Bak, Thomas; Bendtsen, Jan Dimon; Ravn, Anders Peter

    2003-01-01

    We present a hybrid systems solution to the problem of trajectory tracking for a four-wheel steered four-wheel driven mobile robot. The robot is modelled as a non-holonomic dynamic system subject to pure rolling, no-slip constraints. Under normal driving conditions, a nonlinear trajectory tracking...

  14. Motion Planning for a Wheeled Robot (Kinematic Approximation)

    Science.gov (United States)

    Larin, V. B.

    2005-02-01

    The motion-planning problem for a wheeled robot is solved in kinematic approximation. The solution is given for robots with one and two steering wheels. The results of solving the problem for a specific system are compared with the results obtained by other authors

  15. Motion Planning for a Mobile Robot with Two Steerable Wheels

    Science.gov (United States)

    Larin, V. B.

    2005-05-01

    A nonholonomic model of a wheeled robot with two steerable wheels is considered. The model accounts for dynamic effects. The motion-planning problem for this model is solved by reducing it to a linear two-point boundary-value problem

  16. The Wheels of Stress Go 'Round and 'Round

    Science.gov (United States)

    Brey, Rebecca A.; Clark, Susan E.

    2012-01-01

    "The Wheels of Stress Go Round and Round" teaching idea uses three activity wheels to reinforce stress-related content and concepts. After presenting a definition of stress, the instructor assists students in identifying stressors, and aids in formulating a list of negative, reactive behaviors and a list of positive coping mechanisms. Using…

  17. Complex eigenvalue analysis of railway wheel/rail squeal | Goo ...

    African Journals Online (AJOL)

    Wheel/rail squeal noise of trains is one of the challenging problems of trains, but a successful model for the squeal problem has not been presented until now. In this study, a new approach was presented to investigate the basic mechanism of the wheel/rail squeal noise, using complex eigenvalue analysis by the finite ...

  18. Residual stress distribution of wheel tread for freight car due to aging effect

    Science.gov (United States)

    Kwon, Seok-Jin; Lee, Dong-Hyung; Seo, Jung-Won; Kwon, Sung-Tae

    2010-03-01

    Recently, several wheels for freight car in running had experienced the wheel failure due to fatigue crack, overheat braking and other factors. Severe heating of the wheel during tread braking was believed to be a contributing factor of derailment. It is necessary to evaluate the residual stress in wheel tread in order to manage the safety of wheel. In the present paper, the residual stress of wheel regarding to running distance using x-ray diffraction system is investigated. The result shows that the residual stress of wheel is depend on the running distance, wear rate of wheel and thermal gradient during brake application.

  19. The excavating sponges of the Santa Marta area, Colombia, with description of a new species

    NARCIS (Netherlands)

    Hofman, Caroline C.; Kielman, Margriet

    1992-01-01

    From June till December 1987 an inventory of the excavating sponges of the Santa Marta area, Colombian Caribbean, was made by scuba diving to depths not exceeding 18 m. Sixteen species were recorded and compared morphologically, using spicule sizes, papillae shapes, and excavation characteristics.

  20. The role of wood hardness in limiting nest site selection in avian cavity excavators

    Science.gov (United States)

    Teresa J. Lorenz; Kerri T. Vierling; Timothy R. Johnson; Philip C. Fischer

    2015-01-01

    Woodpeckers and other primary cavity excavators (PCEs) are important worldwide for excavating cavities in trees, and a large number of studies have examined their nesting preferences. However, quantitative measures of wood hardness have been omitted from most studies, and ecologists have focused on the effects of external tree- and habitat-level features on nesting....

  1. Deformations and damage to buildings adjacent to deep excavations in soft soils

    NARCIS (Netherlands)

    Korff, M.

    2009-01-01

    The objective of this study is to gain insight into mechanisms of soil-structure interaction for buildings adjacent to deep excavations and to find a reliable method to design and monitor deep excavations in urban areas with soft soil conditions. The research focuses on typical Dutch conditions. The

  2. Drill, baby, drill: the influence of woodpeckers on post-fire vertebrate communities through cavity excavation

    Science.gov (United States)

    Gina L. Tarbill; Patricia N. Manley; Angela M. White

    2015-01-01

    Several studies have addressed the importance of woodpeckers as ecological engineers in forests due to their excavation of cavities. Although research in green, unburned forests has identified the influence of different excavators on secondary use by cavity-dependent species, little is known about the relative importance of cavities created by woodpeckers in recently...

  3. Excavation of Precious-Metal-Based Alloy Nanoparticles for Efficient Catalysis.

    Science.gov (United States)

    Tao, Franklin Feng

    2016-12-05

    Methods have recently been developed for the synthesis of excavated alloy nanoparticles. However, various challenges still need to be overcome for a broad range of excavated nanoparticles with different sizes, surface structures, compositions, and constituent elements to be available for chemical and energy transformations through thermal catalysis and electrocatalysis. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Relevant risk factors associated with the construction of excavated tunnel cross-passages in soft soils

    NARCIS (Netherlands)

    Chivatá Cárdenas, Ibsen; Al-Jibouri, Saad H.S.; Halman, Johannes I.M.

    2013-01-01

    This paper reports on an investigation of risk factors associated with the construction of excavated tunnel cross-passages in soft soils. The investigation focused on excavations where freezing technologies are used to provide temporary support. The relevant risk factors and their associated

  5. Investigation of Hexavalent Chromium Flux to Groundwater at the 100-C-7:1 Excavation Site

    Energy Technology Data Exchange (ETDEWEB)

    Truex, Michael J.; Vermeul, Vincent R.; Fritz, Brad G.; Mackley, Rob D.; Horner, Jacob A.; Johnson, Christian D.; Newcomer, Darrell R.

    2012-11-16

    Deep excavation of soil has been conducted at the 100-C-7 and 100-C-7:1 waste sites within the 100-BC Operable Unit at the Department of Energy (DOE) Hanford Site to remove hexavalent chromium (Cr(VI)) contamination with the excavations reaching to near the water table. Soil sampling showed that Cr(VI) contamination was still present at the bottom of the 100-C-7:1 excavation. In addition, Cr(VI) concentrations in a downgradient monitoring well have shown a transient spike of increased Cr(VI) concentration following initiation of excavation. Potentially, the increased Cr(VI) concentrations in the downgradient monitoring well are due to Cr(VI) from the excavation site. However, data were needed to evaluate this possibility and to quantify the overall impact of the 100-C-7:1 excavation site on groundwater. Data collected from a network of aquifer tubes installed across the floor of the 100-C-7:1 excavation and from temporary wells installed at the bottom of the entrance ramp to the excavation were used to evaluate Cr(VI) releases into the aquifer and to estimate local-scale hydraulic properties and groundwater flow velocity.

  6. Characterization of Wheel Surface Topography in cBN Grinding

    Science.gov (United States)

    Fujimoto, Masakazu; Ichida, Yoshio; Sato, Ryunosuke; Morimoto, Yoshitaka

    The wheel surface topography in the grinding process with vitrified cBN wheels has been investigated on the basis of 3-dimensional analysis using a multi-probe SEM, and the relationships between these results and the grinding characteristic parameters have been discussed. Moreover, the change of the wheel surface profile in the grinding process has been evaluated using fractal analysis. There are two regions: an initial wear region and a steady-state wear region, in the grinding process. In the initial wear region, a rapid decrease of grinding force and a rapid increase of wheel wear occur with increasing stock removal. In the steady-state wear region, the micro self-sharpening phenomenon owing to the micro fracture as well as the attritious wear of cutting edge occurs. The change in fractal dimension of the wheel surface is closely related to the change of grinding force dominated by the wear behavior of grain cutting edges.

  7. CLINICAL COURSE OF INFLAMMATORY CHOROIDAL NEOVASCULARIZATION ASSOCIATED WITH FOCAL CHOROIDAL EXCAVATION.

    Science.gov (United States)

    Corbelli, Eleonora; Sacconi, Riccardo; Querques, Lea; Carnevali, Adriano; Giuffrè, Chiara; Rabiolo, Alessandro; Bandello, Francesco; Querques, Giuseppe

    2017-10-23

    To report the clinical course of focal choroidal excavation associated with choroidal neovascularization in a case of choroidal inflammation. Case report. A 41-year-old man presented with blurred vision and metamorphopsia in his left eye. Multimodal imaging including optical coherence tomography angiography showed nonconforming focal choroidal excavation in the setting of choroidal inflammation and the presence of choroidal neovascularization at the border of the excavation, nicely visualized by optical coherence tomography angiography. Pattern alteration from nonconforming to conforming focal choroidal excavation and choroidal neovascularization involution were observed after treatment with oral steroids. Multimodal imaging, including optical coherence tomography angiography, allowed to detect and monitor pattern focal choroidal excavation transformation and choroidal neovascularization reduction after treatment with oral steroids.

  8. Dam geology and basic treatment(2). Adit substitution technique and measures against landslide involved in excavation

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Kin' ichi (Kinki Geological Center, Co. Ltd., Kyoto, Japan (JP))

    1988-12-25

    This paper discusses the adit substitution technique which is a method for special treatment of dams and measures against landslide involved in excavation. The adit substitution technique consists of excavating an adit in the natural ground, excavating another adit which is in contact with the first adit and is at a level higher than the first adit, placing concrete from the upper adit to the lower adit to fill first adit completely with concrete, excavating a third adit, filling the second adit with concrete similarly, and proceeding with this process to construct a water barrier within the natural ground until the water barrier reaches the required height. The paper explains examples of this technique used on four dams. It also explains examples of measures against excavation-induced landslide adopted on three dams. 13 refs., 8 figs., 2 tabs.

  9. The influence of friction coefficient and wheel/rail profiles on energy dissipation in the wheel/rail contact

    NARCIS (Netherlands)

    Idarraga Alarcon, G.A.; Burgelman, N.D.M.; Meza Meza, J.; Toro, A.; Li, Z.

    2015-01-01

    This work investigates the energy dissipation in a wheel/rail system through friction work modeling. In order to identify the effect of the friction coefficient on the energy dissipation in the wheel/rail contact, several simulations were performed using a 3D multibody model of a railway vehicle

  10. 77 FR 70478 - RG Steel Wheeling, LLC, Wheeling Office, A Division Of RG Steel, LLC, Including On-Site Leased...

    Science.gov (United States)

    2012-11-26

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF LABOR Employment and Training Administration RG Steel Wheeling, LLC, Wheeling Office, A Division Of RG Steel, LLC, Including On-Site Leased Workers From Pro Unlimited and Green Energy Initiatives LLC, Including Workers Whose Wages Were Reported Through Severstal...

  11. Installation of the first of the big wheels of the ATLAS muon spectrometer, a thin gap chamber (TGC) wheel

    CERN Multimedia

    Claudia Marcelloni

    2006-01-01

    The muon spectrometer will include four big moving wheels at each end, each measuring 25 metres in diameter. Of the eight wheels in total, six will be composed of thin gap chambers for the muon trigger system and the other two will consist of monitored drift tubes (MDTs) to measure the position of the muons

  12. Association of focal choroidal excavation with age-related macular degeneration.

    Science.gov (United States)

    Kuroda, Yoshimasa; Tsujikawa, Akitaka; Ooto, Sotaro; Yamashiro, Kenji; Oishi, Akio; Nakanishi, Hideo; Kumagai, Kyoko; Hata, Masayuki; Arichika, Shigeta; Ellabban, Abdallah A; Yoshimura, Nagahisa

    2014-09-04

    To study the prevalence, tomographic features, and clinical characteristics of focal choroidal excavation (FCE) in eyes with exudative age-related macular degeneration (AMD). We examined 243 consecutive eyes with exudative AMD with a prototype swept-source optical coherence tomography (OCT) system. Three-dimensional images of the macular area, covering 6 × 6 mm(2), were reconstructed by segmentation of the outer surface of the retinal pigment epithelium. Three-dimensional swept-source OCT revealed 15 excavations in 12 eyes (4.9%); 10 had a single excavation and 2 had multiple excavations (2 and 3 excavations, respectively). In multiaveraged scans, unusual choroidal tissue was found beneath 5 excavations, bridging the excavation with the outer choroidal boundary. Additionally, the suprachoroidal space was observed beneath 7 excavations-the outer choroidal boundary appeared to be pulled inward by this bridging tissue. In 9 excavations, color fundus photographs showed pigmentary disturbance. Fourteen excavations (93.3%) were located within or adjacent to the choroidal neovascularization area. Compared with eyes without FCE, in eyes with FCE, the mean age was significantly higher (P = 0.040) and mean visual acuity was significantly better (P = 0.014). In addition, polypoidal lesions were observed in 8 of 12 eyes with FCE, but they appeared to have a limited effect on either the rate of FCE (P = 0.44) or the clinical characteristics of the eyes. While FCE may be partially related to the choroidal neovascularization associated with exudative AMD, other factors may also influence this association. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  13. Clinical and optic coherence tomography findings of focal choroidal excavation in Chinese patients.

    Science.gov (United States)

    Guo, Jie; Zhong, Lu; Jiang, Chunhui; Zhou, Xin; Xu, Gezhi; Wang, Wenji; Wang, Yuliang

    2014-05-06

    To describe the clinical and optical coherence tomography (OCT) features of focal choroidal excavation in Chinese patients. Retrospectively, thirty-seven eyes (in 31 patients) that demonstrated focal choroidal excavation on spectral-domain OCT were collected. Their clinical characteristics and other features were also collected and analyzed. In total, 42 focal choroidal excavations were identified in 31 patients, including 25 unilateral and 6 bilateral (37 eyes). The abnormal changes in these eyes with choroidal excavation were more prominent at the outer part of the neuro-retina, the retinal pigment epithelium (RPE) and the choroid. The average transverse diameter and depth of the excavations were 670.8 μm and 106.9 μm, respectively. In addition to the conforming and nonconforming types, the excavations could also be classified into 2 types according to their shape: type 1 - small with a sharp, cut-down contour; and type 2 - slightly larger with a gradual edge. The transverse diameter/depth ratio of the two types were significantly different (type1: 4.57 ± 1.65, type 2: 10.0 ± 5.2; p = 0.000). Four central serous chorioretinopathy (CSCR) cases were confirmed by fluorescein angiography; in these cases, the retinal detachment was larger than the area of excavation, and the inner segment/outer segment (IS/OS) and external limiting membrane (ELM) were above those of the normal part. Concomitant CNV was also found in another 2 cases. Focal choroidal excavation was not uncommon in Chinese patients. The choroid and the RPE at the excavation were impaired or vulnerable to other damage. Additionally, OCT might be useful in the differentiation between nonconforming excavations and ones with CSCR.

  14. Photos taken during the assembly of the first 4-plane wheel prototype, built in 1998.

    CERN Multimedia

    Dixon, N.

    1998-01-01

    Photo 1 - End Cap. 4 -plane wheel prototype - One plane complete. Photo 2 - End Cap. 4 -plane wheel prototype - Radiator Foil. Photo 3 - End Cap. 4-plane wheel prototype - Glueing technique. Photo 4 - End Cap. 4-plane wheel prototype - Glueing ring. Photo 5 - End Cap. 4-plane wheel prototype - Glueing ring. Photo 6 - End Cap. 4-plane wheel prototype - Completed straw plane. Photo 7 - End Cap. 4-plane wheel prototype - Webs on assembly table. Photo 8 - End Cap. 4-plane wheel prototype - Operations on inner ring. Photo 9 - End Cap. 4-plane wheel prototype - Glueing operations. Photo 10 - End Cap. 4-plane wheel prototype - Glueing equipment. Photo 11 - End Cap. 4-plane wheel prototype - Assembly of 4-plane wheel. Photo 12 - End Cap. 4-plane wheel prototype - Positioning tool. Photo 13 - End Cap. 4-plane wheel prototype - Testing. Photo 14 - End Cap. 4-plane wheel prototype - Glued to web ring 2. Photo 15 - End Cap. 4-plane wheel prototype - Positioning tool. Photo 16 - End Cap. 4-plane wheel prototype - Detail o...

  15. Rover's Wheel Churns Up Bright Martian Soil

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Spirit acquired this mosaic on the mission's 1,202nd Martian day, or sol (May 21, 2007), while investigating the area east of the elevated plateau known as 'Home Plate' in the 'Columbia Hills.' The mosaic shows an area of disturbed soil, nicknamed 'Gertrude Weise' by scientists, made by Spirit's stuck right front wheel. The trench exposed a patch of nearly pure silica, with the composition of opal. It could have come from either a hot-spring environment or an environment called a fumarole, in which acidic, volcanic steam rises through cracks. Either way, its formation involved water, and on Earth, both of these types of settings teem with microbial life. Spirit acquired this mosaic with the panoramic camera's 753-nanometer, 535-nanometer, and 432-nanometer filters. The view presented here is an approximately true-color rendering.

  16. Wheel liner design for improved sound and structural performances

    Science.gov (United States)

    Oltean, Alexandru; Diaconescu, Claudiu; Tabacu, Ştefan

    2017-10-01

    Vehicle noise is composed mainly of wheel-road noise and noise from the power unit. At low speeds power unit noise dominates while at high speeds wheel-road noise dominates as wheel-road noise level increases approximately logarithmically with speed. The wheel liner is designed as a component of the vehicle that has a multiple role. It has to prevent the dirt or water from the road surface that are engaged by the wheel to access the engine/front bay. Same time it has the important role to reduce perceived noised in the passenger’s compartment that comes from the wheel-road interaction. Progress in plastic injection moulding technology allowed for new structures to be developed – nonwoven materials in combination with a PP based carrier structure which benefits from a cell structure caused by MuCell injection moulding. The results are light parts with increased sound absorption performances. An adapted combination of materials and production processes can provide the solution for stiff yet soundproofing structures valued for modern vehicles. Sound absorption characteristics of materials used for wheel liners applications were reported in this study. Different polypropylene and polyester fibre-based thermally bonded nonwovens varying in weight and thickness were investigated. Having as a background the performances of the nonwoven material the microcellular structure was part of the analysis. Acoustical absorptive behaviour was explained by analysing the results obtained using the impedance tube and correlating with the knowledge of materials structure.

  17. Diagnostics of the wheel thread of railway rolling stock

    Directory of Open Access Journals (Sweden)

    S. Yu. Buryak

    2013-02-01

    Full Text Available Purpose. At present, the devastating impact of faulty wheels on rails on the move is a major problem of railway transport. This factor is one of the most important, which causes the shift from traditional manual methods of verification and external examination to the automated diagnostic system of rolling stock in operation. Methodology. To achieve this goal the main types of wheel damages and the way they appear are analyzed. The methods for defects and abnormalities of the wheel thread determining as well as their advantages and disadvantages were presented. Nowadays these methods are under usage in both the international practice and in the one of the CIS countries. Findings. The faulty wheel sound on the move was researched and analyzed. The necessity of using the automated system, enabling one to reduce significantly the human factor is substantiated. Originality. The method to determine the wheel thread damage on the basis of a sound diagnostic is proposed. Practical value. Automatic tracking system of the wheels condition allows performing their more qualitative diagnostics, detecting a fault at the early stage and forecasting the rate of its extension. Besides detecting the location of the faulty wheel in the rolling stock, it is also possible to trace the dynamics of the fault extension and to give the recommendations on how to eliminate it.

  18. 76 FR 19129 - Excavations (Design of Cave-in Protection Systems); Extension of the Office of Management and...

    Science.gov (United States)

    2011-04-06

    ... Occupational Safety and Health Administration Excavations (Design of Cave-in Protection Systems); Extension of... information collection requirements contained in the Standard on Excavations (Design of Cave-in Protection... use protective systems to prevent cave-ins during excavation work; these systems include sloping the...

  19. Intelligent Risk Assessment for Dewatering of Metro-Tunnel Deep Excavations

    Directory of Open Access Journals (Sweden)

    X. W. Ye

    2012-01-01

    Full Text Available In recent years, China has been undergoing a metro railway construction boom in order to alleviate the urban traffic congestion problem resulting from the rapid urbanization and population growth in many metropolises. In the construction of metro systems, deep excavations and continuous dewatering for construction of the metro tunnels and stations remain a challenging and high risk task in densely populated urban areas. Intelligent computational methods and techniques have exhibited the exceptional talent in dealing with the complicated problems inherent in the deep excavation and dewatering practice. In this paper, an intelligent risk assessment system for deep excavation dewatering is developed and has been applied in the project of Hangzhou Metro Line 1 which is the first metro line of the urban rapid rail transit system in Hangzhou, China. The specific characteristics and great challenges in deep excavation dewatering of the metro-tunnel airshaft of Hangzhou Metro Line 1 are addressed. A novel design method based on the coupled three-dimensional flow theory for dewatering of the deep excavation is introduced. The modularly designed system for excavation dewatering risk assessment is described, and the field observations in dewatering risk assessment of the airshaft excavation of Hangzhou Metro Line 1 are also presented.

  20. Two cases of focal choroidal excavation detected by spectral-domain optical coherence tomography.

    Science.gov (United States)

    Katome, Takashi; Mitamura, Yoshinori; Hotta, Fumika; Niki, Masanori; Naito, Takeshi

    2012-01-01

    To report the clinical findings of 2 patients with focal choroidal excavation in the macula detected by spectral-domain optical coherence tomography (SD-OCT). Three eyes of 2 patients with a focal macular choroidal excavation detected by SD-OCT were studied. The eyes were examined by fundus autofluorescence (FAF), fluorescein angiography, fundus-related microperimetry, and multifocal electroretinography (mfERG). In spite of a complaint of metamorphopsia, the visual acuity was normal in 2 eyes. SD-OCT demonstrated a choroidal excavation in the macula but the foveal contour was normal in 3 eyes. The excavation involved the outer retinal layers up to the external limiting membrane in all eyes, and a type 2 secondary choroidal neovascularization (CNV) developed in 1 of the 3 eyes. There were areas of hypoautofluorescence in the FAF images, and areas of decreased retinal sensitivity determined by microperimetry. These areas corresponded to the choroidal excavation in all eyes. The P1 amplitudes of the mfERGs were decreased in the fovea of 1 eye without a CNV. The choroidal excavation remained stable for 3 years in 2 eyes, a secondary CNV developed in 1 eye during the course of the disease. More cases and longer follow-up periods will be necessary to determine the etiology, clinical course, and visual prognosis of eyes with a choroidal excavation.

  1. Arthroscopic Inside-Out Repair of a Meniscus Bucket-Handle Tear Augmented With Bone Marrow Aspirate Concentrate.

    Science.gov (United States)

    Muckenhirn, Kyle J; Kruckeberg, Bradley M; Cinque, Mark E; Chahla, Jorge; DePhillipo, Nicholas N; Godin, Jonathan A; LaPrade, Robert F

    2017-08-01

    Bucket-handle tears of the meniscus comprise nearly 10% of all meniscus tears and commonly affect the young male population. Displacement of the free segment can lead to significant pain and disability, necessitating reduction and surgical treatment. General contraindications include malalignment, severe arthritis, significant comorbidities, or chronic asymptomatic tears, but otherwise repair should almost always be performed. Options for surgical treatment include partial meniscectomy and arthroscopic repair using an all-inside, outside-in, or inside-out technique. The purpose of this Technical Note is to detail our arthroscopic inside-out repair technique augmented with bone marrow aspirate concentrate.

  2. Determination of p-y Curves for Bucket Foundations in Silt and Sand Using Finite Element Modelling

    DEFF Research Database (Denmark)

    Vethanayagam, Vinojan; Ibsen, Lars Bo

    Design of offshore wind turbine foundations are today based on analytical formulas, which describes the link between a displacement, y, and the associated soil pressure, p. The formulas are empirically developed on slender piles with a slenderness ratio L=D > 30, but foundations of today are less...... herefore shows to be more versatile and precise than the formulation suggested by Østergaard et al. [2015]. The developed p-y formulations are functions of the effective vertical in-situ stress, soil stiffness, diameter of the bucket and the internal friction angle/the undrained shear strength....

  3. The use of computer-assisted FACE for minimal-invasive caries excavation.

    Science.gov (United States)

    Ganter, Philip; Al-Ahmad, Ali; Wrbas, Karl-Thomas; Hellwig, Elmar; Altenburger, Markus Jörg

    2014-04-01

    Caries excavation is still a demanding procedure today. In the past years, methods using light-induced fluorescence have proven their ability to detect bacteria remaining in the tooth's hard tissues. However, methods to control the complete removal of infected dentine have not yet been validated. The aim of the present study was to evaluate the degree of dentine removal during caries excavation using a camera- and software-based device as a guide for fluorescence-aided caries excavation (FACE) in comparison to visual-tactile inspection and a dye-staining method. One hundred teeth with carious lesions (C3) were randomly allocated to four groups and excavated with the respective method as primary excavation control method. When the first method indicated complete caries excavation, a second method was used to affirm this. Subsequently, dentine samples were taken to determine residual contamination using PCR. After embedding and sectioning the teeth dentine, microhardness was measured perpendicular to the cavity floor. By using the camera- and software-based device, 94 % of the cavities tested were free of bacterial contamination. All cavities excavated with the dye-staining or visual-tactile control method were free of bacterial contamination but resulted in a significantly higher dentine removal. The camera- and software-assisted caries excavation seems to be an adequate method to remove contaminated dentine without removing affected dentine. Beside its original application to monitor carious, the device is safe, effective, and easy to use for guided caries excavation and is of worth for both everyday practice and undergraduate education.

  4. Life Assessment and Life Extension of an Aircraft Wheel

    Directory of Open Access Journals (Sweden)

    M. Aghaie-Khafri

    2012-01-01

    Full Text Available The effect of heat treatment and shot peening on the fatigue life of an aluminum aircraft wheel was studied. The effect of residual stress and heat treatment on the fatigue of specimens was studied by means of fatigue testing, residual stress measurement, and fractography. Finite element simulation was used for life assessment and evaluation of the effect of surface treatments on the life extension of the aircraft wheel. The results obtained show that the operational life of the aircraft wheel extended by imposed compressive residual stress and aging treatment.

  5. Model-based analysis and simulation of regenerative heat wheel

    DEFF Research Database (Denmark)

    Wu, Zhuang; Melnik, Roderick V. N.; Borup, F.

    2006-01-01

    The rotary regenerator (also called the heat wheel) is an important component of energy intensive sectors, which is used in many heat recovery systems. In this paper, a model-based analysis of a rotary regenerator is carried out with a major emphasis given to the development and implementation...... of mathematical models for the thermal analysis of the fluid and wheel matrix. The effect of heat conduction in the direction of the fluid flow is taken into account and the influence of variations in rotating speed of the wheel as well as other characteristics (ambient temperature, airflow and geometric size...

  6. Dynamics of omnidirectional unmanned rescue vehicle with mecanum wheels

    Science.gov (United States)

    Typiak, Andrzej; Łopatka, Marian Janusz; Rykała, Łukasz; Kijek, Magdalena

    2018-01-01

    The work presents the dynamic equations of motion of a unmanned six-wheeled vehicle with mecanum wheels for rescue applications derived with the of Lagrange equations of the second kind with multipliers. Analysed vehicle through using mecanum wheels has three degrees of freedom and can move on a flat ground in any direction with any configuration of platform's frame. In order to derive dynamic equations of motion of mentioned object, kinetic potential of the system and generalized forces affecting the system are determined. The results of a solution of inverse dynamics problem are also published.

  7. Dye staining and excavation of a lateral preferential flow network

    Directory of Open Access Journals (Sweden)

    A. E. Anderson

    2009-06-01

    Full Text Available Preferential flow paths have been found to be important for runoff generation, solute transport, and slope stability in many areas around the world. Although many studies have identified the particular characteristics of individual features and measured the runoff generation and solute transport within hillslopes, very few studies have determined how individual features are hydraulically connected at a hillslope scale. In this study, we used dye staining and excavation to determine the morphology and spatial pattern of a preferential flow network over a large scale (30 m. We explore the feasibility of extending small-scale dye staining techniques to the hillslope scale. We determine the lateral preferential flow paths that are active during the steady-state flow conditions and their interaction with the surrounding soil matrix. We also calculate the velocities of the flow through each cross-section of the hillslope and compare them to hillslope scale applied tracer measurements. Finally, we investigate the relationship between the contributing area and the characteristics of the preferential flow paths. The experiment revealed that larger contributing areas coincided with highly developed and hydraulically connected preferential flow paths that had flow with little interaction with the surrounding soil matrix. We found evidence of subsurface erosion and deposition of soil and organic material laterally and vertically within the soil. These results are important because they add to the understanding of the runoff generation, solute transport, and slope stability of preferential flow-dominated hillslopes.

  8. Groundwater flow modelling of the excavation and operational phases - Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Urban (Computer-aided Fluid Engineering AB, Lyckeby (Sweden)); Follin, Sven (SF GeoLogic AB, Taeby (Sweden))

    2010-07-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different climate conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. The modelling study reported here presents calculated inflow rates, drawdown of the groundwater table and upconing of deep saline water for different levels of grouting efficiency during the excavation and operational phases of a final repository at Forsmark. The inflow calculations are accompanied by a sensitivity study, which among other matters handles the impact of parameter heterogeneity, different deposition hole rejection criteria, and the SFR facility (the repository for short-lived radioactive waste located approximately 1 km to the north of the investigated candidate area for a final repository at Forsmark). The report also presents tentative modelling results for the duration of the saturation phase, which starts once the used parts of the repository are being backfilled.

  9. Does Avalanche Shovel Shape Affect Excavation Time: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Kurt Schindelwig

    2017-05-01

    Full Text Available In Europe and North America, approximately 150 fatalities occur as a result of avalanches every year. However, it is unclear whether certain shovel shapes are more effective than others in snow removal during avalanche victim recovery. The objective was to determine the performance parameters with a developed standardized test using different shovel shapes and to determine sex-specific differences. Hence, several parameters were determined for clearing the snow from a snow filled box (15 men, 14 women. A flat (F and a deep (D shovel blade with the shaft connected straight (S or in clearing mode (C were used for the investigation of the shovel shapes FS, DC and the subsequent use of DC&DS. Mean snow mass shifted per unit time increased significantly from 1.50 kg/s with FS to 1.71 kg/s (14% with DS and further to 1.79 kg/s (4% with DC&DS for all participants. Snow mass shifted per unit time was 44% higher (p < 0.05 for men than for women. In excavation operations, the sex-specific physical performance should be taken into account. The results were limited to barely binding snow, because only with this snow did the tests show a high reliability.

  10. Focal choroidal excavation in patients with central serous chorioretinopathy

    Science.gov (United States)

    Luk, F O J; Fok, A C T; Lee, A; Liu, A T W; Lai, T Y Y

    2015-01-01

    Purpose To evaluate the prevalence and clinical features of focal choroidal excavation (FCE) in patients presenting with central serous chorioretinopathy (CSC). Methods This is a retrospective consecutive case series of consecutive patients with CSC who were referred for spectral domain optical coherence tomography (SD-OCT) between January 2010 and December 2011. Medical records were reviewed and clinical features including presence of FCE in SD-OCT, fluorescence angiography (FA), and indocyanine green angiography (ICGA) were studied. Results Among the 116 CSC patients assessed, FCE was found in 11 eyes of 7 (6.0%) patients. FCE was associated with subretinal fluid in six eyes of six patients and serous pigment epithelial detachment in three eyes of two patients. The mean central subfield retinal thickness of CSC eyes with FCE was 283.7 μm, compared with 377.5 μm for CSC eyes without FCE (Mann–Whitney U-test, P=0.020). Five FCE eyes of five patients had focal leakage on FA. Choroidal hyperpermeability on ICGA was found in seven CSC eyes with FCE, with four eyes showing hypofluorescent spot corresponding to the FCE. After a mean follow-up of 16 months, visual acuity of all 11 eyes with FCE remained stable or improved at the last follow-up. Conclusion FCE is not an uncommon feature in patients with CSC and might be associated with choroidal hemodynamic disturbances. PMID:25853402

  11. Choroidal excavation in choroidal osteoma complicated by choroidal neovascularization.

    Science.gov (United States)

    Pierro, L; Marchese, A; Gagliardi, M; Introini, U; Battaglia Parodi, M; Casalino, G; Bandello, F

    2017-12-01

    PurposeTo describe multimodal imaging features of choroidal osteoma (CO) complicated by choroidal neovascularization (CNV) and focal choroidal excavation (FCE).MethodsPatients presenting with CO and CNV between January and October 2016 were considered for this study. Diagnosis of CO was confirmed by ultrasound examination. All patients underwent multimodal imaging including optical coherence tomography (OCT), swept-source OCT angiography (DRI OCT Triton, Topcon, Inc., Tokyo, Japan) and fluorescein angiography (Spectralis HRA+OCT; Heidelberg Engineering, Heidelberg, Germany).ResultsTwo patients (one with bilateral CO) were included in the study. OCT showed a FCE in two eyes of two patients (one in correspondence of the CNV and the other adjacent to the CNV). OCT-A demonstrated presence of microvascular flow within neovascular network of the CNVs. Decalcification of the tumor was noted in correspondence of one eye with FCE.ConclusionsFCE may be found in eyes with choroidal osteoma and CNV. OCT-A was a valuable tool for detection of CNV complicating choroidal osteoma. Decalcification of choroidal osteoma may represent a common pathogenic pathway for development of FCE and CNV in choroidal osteoma.

  12. CHOROIDAL NEVI WITH FOCAL CHOROIDAL EXCAVATION AND POLYPOIDAL CHOROIDAL NEOVASCULARIZATION.

    Science.gov (United States)

    Simhaee, Daniel; Dolz-Marco, Rosa; Freund, K Bailey

    2017-08-10

    To report two cases of choroidal nevi associated with focal choroidal excavation (FCE) and polypoidal choroidal neovascularization (PCN). Report of two patients with choroidal nevi showing FCE and PCN who underwent multimodal imaging including color fundus photography, fluorescein angiography, indocyanine green angiography, fundus autofluorescence, spectral domain optical coherence tomography, swept-source optical coherence tomography, and optical coherence tomography angiography. Two patients presented with choroidal nevi associated with FCE and PCN. In the first case, a 74-year-old woman, the nevus had sharp margins, a deep FCE, surrounding drusen, and subretinal exudation at its inferior edge due to PCN that responded well to intravitreal anti-vascular endothelial growth factor therapy. In the second case, a 64-year-old woman, the nevus had ill-defined margins, a shallow FCE, and angiographic evidence of PCN without associated exudation. There have been several reports showing an association of either choroidal nevi or FCE with PCN. To our knowledge, there have been no previous reports of FCE identified within choroidal nevi, with or without associated PCN. Since, in one of our cases, the FCE was not apparent on clinical examination, the prevalence of FCE within nevi may be underdiagnosed.

  13. EXCAVATION OF PITS (CHANNELS BY IMPACT OF PULSE POWER LOADING

    Directory of Open Access Journals (Sweden)

    Anakhaev Koshkinbai Nazirovich

    2017-08-01

    Full Text Available The paper provides an innovative hydromechanical solution of the problem of profiles development of pits and channels by impact of pulse (blasting power load on a surface of homogeneous soil mass, for example, when excavating solid rocks, frozen soil, etc. Thus, soil would be considered as an ideal heavy liquid (disregarding its mechanical strength and plastic properties. The solution of this problem is achieved by the method of consecutive conformal mappings of physical flow region (in the form of Kirchhoff complex on the region of complex potential (in the form of a rectangle. Thus, the new technique of geometrical image generation of the latter in the presence in the flow region of a fixed point with discontinuous variations of pressure head-flow function and the direction of speed of flow and representation of an elliptic sine of Jacobi by means of elementary functions are used. The received analytical functional dependencies allow to determine an outline of a funnel of the soil ejection and all the required hydromechanical characteristics of flow (head-flow function, function of flow, speed of flow, etc.. Thus, the soil ejection funnel outline (for a benchmark problem completely coincides with subproduct of the known rigorous solution of Lavrentyev-Kuznetsov.

  14. 14 CFR 23.511 - Ground load; unsymmetrical loads on multiple-wheel units.

    Science.gov (United States)

    2010-01-01

    ... multiple-wheel units. 23.511 Section 23.511 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... CATEGORY AIRPLANES Structure Ground Loads § 23.511 Ground load; unsymmetrical loads on multiple-wheel units... distribution, to the dual wheels and tires in each dual wheel landing gear unit. (c) Deflated tire loads. For...

  15. 14 CFR 29.511 - Ground load: unsymmetrical loads on multiple-wheel units.

    Science.gov (United States)

    2010-01-01

    ... multiple-wheel units. 29.511 Section 29.511 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... Requirements Ground Loads § 29.511 Ground load: unsymmetrical loads on multiple-wheel units. (a) In dual-wheel gear units, 60 percent of the total ground reaction for the gear unit must be applied to one wheel and...

  16. 14 CFR 25.511 - Ground load: unsymmetrical loads on multiple-wheel units.

    Science.gov (United States)

    2010-01-01

    ... multiple-wheel units. 25.511 Section 25.511 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION... Loads § 25.511 Ground load: unsymmetrical loads on multiple-wheel units. (a) General. Multiple-wheel...-wheel unit; and (2) In determining the total load on a gear unit with respect to the provisions of...

  17. Determining Wheel-Soil Interaction Loads Using a Meshfree Finite Element Approach Assisting Future Missions with Rover Wheel Design

    Science.gov (United States)

    Contreras, Michael T.; Peng, Chia-Yen; Wang, Dongdong; Chen, Jiun-Shyan

    2012-01-01

    A wheel experiencing sinkage and slippage events poses a high risk to rover missions as evidenced by recent mobility challenges on the Mars Exploration Rover (MER) project. Because several factors contribute to wheel sinkage and slippage conditions such as soil composition, large deformation soil behavior, wheel geometry, nonlinear contact forces, terrain irregularity, etc., there are significant benefits to modeling these events to a sufficient degree of complexity. For the purposes of modeling wheel sinkage and slippage at an engineering scale, meshfree finite element approaches enable simulations that capture sufficient detail of wheel-soil interaction while remaining computationally feasible. This study demonstrates some of the large deformation modeling capability of meshfree methods and the realistic solutions obtained by accounting for the soil material properties. A benchmark wheel-soil interaction problem is developed and analyzed using a specific class of meshfree methods called Reproducing Kernel Particle Method (RKPM). The benchmark problem is also analyzed using a commercially available finite element approach with Lagrangian meshing for comparison. RKPM results are comparable to classical pressure-sinkage terramechanics relationships proposed by Bekker-Wong. Pending experimental calibration by future work, the meshfree modeling technique will be a viable simulation tool for trade studies assisting rover wheel design.

  18. Research on Application of Regression Least Squares Support Vector Machine on Performance Prediction of Hydraulic Excavator

    Directory of Open Access Journals (Sweden)

    Zhan-bo Chen

    2014-01-01

    Full Text Available In order to improve the performance prediction accuracy of hydraulic excavator, the regression least squares support vector machine is applied. First, the mathematical model of the regression least squares support vector machine is studied, and then the algorithm of the regression least squares support vector machine is designed. Finally, the performance prediction simulation of hydraulic excavator based on regression least squares support vector machine is carried out, and simulation results show that this method can predict the performance changing rules of hydraulic excavator correctly.

  19. Modeling of Railway Wheels Made of Austempered Ductile Iron

    Directory of Open Access Journals (Sweden)

    Giętka T.

    2016-12-01

    Full Text Available A person is forced to travel constantly throughout its entire life. The more modern the society, the greater the pace of life, and the greater the need to be present in many places that are distant from each other. Rail transport occupies second place in this regard, after air transport. This means of transportation has many advantages, however the time of travel requires continuous improvement, in particular, to match the competition. One factor limiting the speed of travel is inter-operation between the wheels – rail kinematic pair. When rolling on a rail, a wheel is subject to wear, which unavoidably leads to its degradation. Frequent damage to both the wheel and the rail necessitates consideration of this problem. Because any changes to the rail are very expensive and time-consuming, this paper focuses on possible changes to the wheel.

  20. TECHNOLOGICAL FEATURES OF MANUFACTURE OF REINFORCED RAIL WHEEL

    Directory of Open Access Journals (Sweden)

    I. O. Vakulenko

    2008-01-01

    Full Text Available The results of research of influence of parameters of thermomechanical hardening on the structure, complex of physico-mechanical and service properties of hardened railway wheels are presented.