WorldWideScience

Sample records for bearing capacity

  1. The ultimate bearing capacity of ice beams

    Directory of Open Access Journals (Sweden)

    Li Liang

    2013-02-01

    Full Text Available It is usually proposed that bearing capacity of the ice beam during its interaction with a sloping hydraulic structure is exhausted when tensile stresses in the beam’s cross-section reach some limit. But besides the tensile stress there is a compressive stress during the interaction with a sloping structure. This can change our estimations of the ultimate bearing capacity and load exerted on the structure. The purpose of the study was to estimate influence of the longitudinal compressive stress on the ice beam’s ultimate bearing capacity. The solution was obtained with the program complex LS-DYNA. Results of the mathematical modeling were compared with data of physical experiments conducted by Sodhi. Good correlation of the results gave possibility to conduct wide numerical experiments and to suggest corrections to the existing methodology.

  2. Grouted Pile and Its Bearing Capacity

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The grouting method applied in bored pile is an improvement to the conventional bored pile. Load tests have proved that grouting under the bored pile tip is an effective method to enhance the bearing capacity of the pile and to reduce the pile settlement. In this paper, the grouting technology is described and pile-load test results are discussed. In order to put the grouting method into design practice, the authors analyze the working mechanism of soil compaction. And, based on the theory of cavities expansion in soil mass, approximate formulae are proposed for estimating the bearing capacity of the grouted pile. The theoretical prediction agrees well with the load test results.

  3. Load-Bearing Capacity of Roof Trusses

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Damkilde, Lars; Munch-Andersen, J.

    2004-01-01

    systems such as roof trusses are established and statistical characteristics of the load bearing capacity are determined. The results show that there is a significant increase in the characteristic (nominal) value and a reduction in the coefficient of variation (COV) for typical loads such as permanent...

  4. 24 CFR 3285.202 - Soil classifications and bearing capacity.

    Science.gov (United States)

    2010-04-01

    ... capacity. 3285.202 Section 3285.202 Housing and Urban Development Regulations Relating to Housing and Urban... Soil classifications and bearing capacity. The soil classification and bearing capacity of the soil... bearing capacity must be determined by one or more of the following methods, unless the soil...

  5. Lightweight Aggregate Concrete Beams. Load-bearing Capacity

    DEFF Research Database (Denmark)

    Larsen, Henning; Goltermann, Per; Ingholt, N.U.

    1997-01-01

    This paper deals with the load-bearing capacity of reinforced beams made of lightweight aggregate concrete with open structure and documents formulas for the moment capacity as well as the shear force capacity.......This paper deals with the load-bearing capacity of reinforced beams made of lightweight aggregate concrete with open structure and documents formulas for the moment capacity as well as the shear force capacity....

  6. Lightweight Aggregate Concrete Components. Load-bearing Capacity

    DEFF Research Database (Denmark)

    Larsen, Henning; Ingholt, N.U.; Goltermann, Per

    1996-01-01

    The project presented here deals with the load-bearing capacity of reinforced beams made of lightweight aggregate concrete with open structure and documents expressions for the moment capacity as well as the shear force capacity......The project presented here deals with the load-bearing capacity of reinforced beams made of lightweight aggregate concrete with open structure and documents expressions for the moment capacity as well as the shear force capacity...

  7. Increasing the load bearing capacity of barrel vaults

    NARCIS (Netherlands)

    Kamerling, M.W.

    2011-01-01

    Just after World War II many barrel vaults and domes were built with a structural system, known as Fusée Ceramique. This paper analyses the load bearing capacity of these vaults. Schemes, theories, idealizations and assumptions are analysed, validated and discussed. Methods to increase the load bear

  8. Bearing capacity analysis using the method of characteristics

    Institute of Scientific and Technical Information of China (English)

    Jian-Ping Sun; Zhi-Ye Zhao; Yi-Pik Cheng

    2013-01-01

    Using the method of characteristics,the bearing capacity for a strip footing is analyzed.The method of characteristics leads to an exact true limit load when the calculations of the three terms in the bearing capacity formula are consistent with one collapse mechanism and the soil satisfies the associated flow rule.At the same time,the method of characteristics avoids the assumption of arbitrary slip surfaces,and produces zones within which equilibrium and plastic yield are simultaneously satisfied for given boundary stresses.The exact solution without superposition approximation can still be expressed by Terzaghi's equation of bearing capacity,in which the bearing capacity factor Nyλ is dependent on the dimensionless parameterλand the friction angle φ.The influence of groundwater on the bearing capacity of the shallow strip footing is considered,which indicates that when the groundwater effect is taken into account,the error induced by the superposition approximation can be reduced as compared with dry soil condition.The results are presented in the form of charts which give the modified value (yλcw/Nyλc) of bearing capacity factor.Finally,an approximated analytical expression,which provides results in close agreement with those obtained by numerical analysis in this paper,has been suggested for practical application purposes.

  9. Seismic ultimate bearing capacity of strip footings on slope

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The influence of earthquake forces on ultimate bearing capacity of foundations on sloping ground was studied. A solution to seismic ultimate bearing capacity of strip footings on slope was obtained by utilizing pseudo-static analysis method and taking the effect of intermediate principal stress into consideration. Based on limit equilibrium theory, the formulae for computing static bearing capacity factors, Nq, Nc, Nγ, and dynamic bearing capacity factors, Nqd, Ncd, Nγd, which are associated with surcharge, cohesion and self-weight of soils respectively, were presented. A great number of analysis calculations were carried out to obtain the relationship curves of the static and dynamic bearing capacity factors versus various calculation parameters. The curves can serve as the practical engineering design. The calculation results also show that when the values of horizontal and vertical seismic coefficients are 0.2, the dynamic bearing capacity factors Nqd, Ncd and Nγd, in which the effects of intermediate principal stress are taken into consideration, increase by 4%-42%, 3%-27% and 34%-57%, respectively.

  10. Bearing capacity and mechanical behavior of CFG pile composite foundation

    Institute of Scientific and Technical Information of China (English)

    陈秋南; 赵明华; 周国华; 张主华

    2008-01-01

    CFG pile (i.e., pile constructed by granular materials of cement, fly-ash and gravel) composite foundation is applied in subsoil treatment widely and successfully. In order to have a further study of this kind of subsoil treatment technology, the influencing factors and calculation methods of the vertical bearing capacity of single CFG pile and the CFG pile composite foundation were discussed respectively. And based on the obtained solutions, effects by the cushion and measurements to reduce negative friction area were analyzed. Moreover, the developing law of settlement and bearing capacity eigenvalue controlled by the material strength with the increase of load were given for the CFG composite foundation. The in-situ static load test was tested for CFG pile. The results of test show that the maximum test load or half of the ultimate load is used from all the points of test, the average bearing capacity eigenvalue of single pile is 390 kN, and slightly greater than the design value of bearing capacity. The bearing capacity eigenvalues of composite foundation for 3 piles are greater than 300 kPa, and the mechanical properties of CFG pile composite foundation are almost identical in the case of the same load and cushion thickness. The pile-soil stress ratio and the load-sharing ratio can be adjusted through setting up cushion thickness.

  11. The Influence of Time on Bearing Capacity of Driven Piles

    DEFF Research Database (Denmark)

    Jensen, J. Lysebjerg; Augustesen, A.; Sørensen, Carsten S.

    2004-01-01

    In Danish engineering practice, one of the ways to determine the ultimate bearing capacity of an axially loaded pile is by means of geostatic formulas. In the equation describing the contribution from the shaft friction to the total bearing capacity for piles located entirely or partly in clay......, a regeneration factor appears. The regeneration factor accounts for effects of dissipation of pore pressure due to pile driving and true time effects such as ageing on the ultimate bearing capacity. Normally the factor is 0.4 but in this paper, the influence of the undrained shear strength and time...... on the regeneration factor is investigated. A relation between the quantities is proposed, which in the end may imply an economical benefit in the design of pile foundations....

  12. Numerical analysis of soil bearing capacity by changing soil characteristics

    Directory of Open Access Journals (Sweden)

    Mehdi Khodashenas Pelko

    2009-10-01

    Full Text Available In this research work by changing different parameters of soil foundation like density, cohesion and foundation depth and width of square foundation at angle of friction of 0° to 50° with increment of 5°, numerically safe bearing capacity of soil foundation is calculated and it is attempted to assess economical dimension of foundation as well as understanding variation range of bearing capacity at different degree. It could help of civil engineering in design of foundations at any situation.

  13. Bearing Capacity of Foundations subjected to Impact Loads

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Jakobsen, Kim Parsberg

    1996-01-01

    In the design process for foundations, the bearing capacity calculations are normally restricted to monotonic loads. Even in cases where the impact load is of significance the dynamic aspects are neglected by use of a traditional deterministic ultimate limit state analysis. Nevertheless it is com......In the design process for foundations, the bearing capacity calculations are normally restricted to monotonic loads. Even in cases where the impact load is of significance the dynamic aspects are neglected by use of a traditional deterministic ultimate limit state analysis. Nevertheless...

  14. Bearing capacity evaluation of rubblized concrete pavements

    Directory of Open Access Journals (Sweden)

    González, M.

    2009-03-01

    Full Text Available The paper presents the findings of a research work performed on a real scale concrete pavement project where Rubblizing technology was used for its structural rehabilitation. Rubblizing may be defined as a fracture technique in which a concrete pavement slab is transformed in a granular base with a very high Modulus. This technique, fractures the concrete slab in angular pieces by using a concentrated dynamic load of low amplitude and high frequency. The research work was based on field study on the rehabilitation of 5 km motorway. The structural evaluations where made, before, during and after one year construction. Measurements and site evaluation where made by using DCP, Light Weight Deflectometer and FWD (on top of asphalt layer and excavating inside pits. The structural capacity of the Rubblized layer was evaluated through theoretical analysis. Because of the anisotropic properties of the Rubblized layer the results are presented using AASHTO structural layer coefficient. The structural layer coefficients recommended are between the range of 0.25 and 0.30 for concrete slabs with thickness grater than 220 mm.El trabajo presenta los resultados de un estudio a escala real de la capacidad estructural de un firme de hormigón rehabilitado utilizando la técnica de Rubblizing. La técnica de Rubblizing ha sido traducida como el pulverizado del firme de hormigón pero, es más bien un efecto combinado de trituración y fracturación de la losa de hormigón en todo su espesor para convertir esta en una base granular de alto módulo. Esta tecnica fractura la losa de hormigón en trozos angulares y entrelazados empleando una carga dinámica concentrada, de baja amplitud y alta frecuencia. La investigación se basó en el estudio de la rehabilitación de 5 km de autopista. Los estudios de la capacidad estructural fueron realizados durante, al término y un año después de la construcción. Para las mediciones y evaluaciones de terreno se utilizó, el

  15. Dynamic Carrying Capacity Analysis of Double-Row Four-Point Contact Ball Slewing Bearing

    OpenAIRE

    Yunfeng Li; Di Jiang

    2015-01-01

    Carrying capacity is the most important performance index for slewing bearings. Maximizing the carrying capacity of slewing bearing is one pursuing goal for the bearing designer; this is usually realized by optimizing the design parameters. A method of analyzing the carrying capacity of double-row four-point contact ball slewing bearing by using dynamic carrying capacity surfaces was proposed in this paper. Based on the dynamic load carrying capacity surface of the slewing bearing, the effect...

  16. The Bearing Capacity of Circular Footings in Sand

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Clausen, Johan; Damkilde, Lars

    2012-01-01

    dependent on the stress level and on the basis of the test results, a non linear Mohr failure criterion has been proposed. This yield criterion has been implemented in a finite element program and an analysis of the bearing capacity of a circular shaped model foundation, diameter 100mm, has been conducted...

  17. Dynamic Carrying Capacity Analysis of Double-Row Four-Point Contact Ball Slewing Bearing

    Directory of Open Access Journals (Sweden)

    Yunfeng Li

    2015-01-01

    Full Text Available Carrying capacity is the most important performance index for slewing bearings. Maximizing the carrying capacity of slewing bearing is one pursuing goal for the bearing designer; this is usually realized by optimizing the design parameters. A method of analyzing the carrying capacity of double-row four-point contact ball slewing bearing by using dynamic carrying capacity surfaces was proposed in this paper. Based on the dynamic load carrying capacity surface of the slewing bearing, the effect of changes of the bearing design parameters, such as axial clearance, raceway groove radius coefficient, and contact angle, on the dynamic carrying capacity of the slewing bearing was researched; the trend and the degree of the effect of the micro changes of the bearing design parameters on the dynamic load carrying capacity of the bearing were discussed, and the results provide the basis for optimizing the design parameter of this type of slewing bearing.

  18. Bearing Capacity of Mixed Pile with Stiffness Core

    Institute of Scientific and Technical Information of China (English)

    YUE Jianwei; JIANG Xinliang; LING Guangrong

    2006-01-01

    To study load transfer mechanism and bearing capacity of a mixed pile with stiffness core (MPSC), which is formed by inserting a precast reinforced concrete pile (PRCP), in-situ tests involving MPSCs with different lengths, diameters, water cement ratios and PRCPs, cement mixed piles, and drilling hole piles, were carried out.Limit bearing capacities, load-settlement curves and stress distribution of MPSCs and mixed piles were obtained.The load transfer between cement soil and PRCP was analyzed by finite element method (FEM).Test results and FEM analysis show that an MPSC has fully utilized the big friction from a cement mixed pile and the high compressive strength from a PRCP which transfers outer top load into the inner cement soil, and that inserting a PRCP into a mixed pile changes the stress distribution of a mixed pile and improves frictional resistance between a mixed pile and soil.The length and the section area on PRCP of an MPSC both have an optimum value.Adopting MPSC is effective in improving the bearing capacity of soft soil ground.

  19. Vertical bearing capacity of pile based on load transfer model

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ming-hua; YANG Ming-hui; ZOU Xin-jun

    2005-01-01

    The load transfer analytical method is applied to study the bearing mechanism of piles with vertical load in this paper. According to the different hardening rules of soil or rock around the pile shaft, such as work-softening, ideal elasto-plastic and work-hardening, a universal tri-linear load transfer model is suggested for the development of side and tip resistance by various types of soil (rock) with the consideration of sediment at the bottom of the pile. Based on the model, a formula is derived for the relationship between the settlement and load on the pile top to determine the vertical bearing capacity, taking into account such factors as the characteristics of the stratum, the side resistance along the shaft, and tip resistance under the pile tip. A close agreement of the calculated results with the measured data from a field test pile lends confidence to the future application of the present approach in engineering practice.

  20. Unconventional Bearing Capacity Analysis and Optimization of Multicell Box Girders

    Directory of Open Access Journals (Sweden)

    Jovan Tepic

    2014-01-01

    Full Text Available This study deals with unconventional bearing capacity analysis and the procedure of optimizing a two-cell box girder. The generalized model which enables the local stress-strain analysis of multicell girders was developed based on the principle of cross-sectional decomposition. The applied methodology is verified using the experimental data (Djelosevic et al., 2012 for traditionally formed box girders. The qualitative and quantitative evaluation of results obtained for the two-cell box girder is realized based on comparative analysis using the finite element method (FEM and the ANSYS v12 software. The deflection function obtained by analytical and numerical methods was found consistent provided that the maximum deviation does not exceed 4%. Multicell box girders are rationally designed support structures characterized by much lower susceptibility of their cross-sectional elements to buckling and higher specific capacity than traditionally formed box girders. The developed local stress model is applied for optimizing the cross section of a two-cell box carrier. The author points to the advantages of implementing the model of local stresses in the optimization process and concludes that the technological reserve of bearing capacity amounts to 20% at the same girder weight and constant load conditions.

  1. Bearing capacity of Skirt circular footing on sand

    Directory of Open Access Journals (Sweden)

    Amr Z. EL Wakil

    2013-09-01

    Full Text Available Skirts are used to improve the bearing capacity of shallow footings on sandy soil by constraining the soil beneath and containing the plastic flow of soil. They are used as an alternative to deep foundations in soils with low strength at the surface. As there has been available little work studying the performance of skirted foundation, we are performing eighteen laboratory experiments on circular steel footings of different diameters and different skirt lengths. The aim of these experiments is to shed some lights on the effects of skirts on the bearing capacity of shallow footings. The effects of skirt length and the relative density of sand on the ultimate load attained were investigated. From the accomplished laboratory tests, it was found that skirts improve appreciably the sustainability of shallow footings to applied load as they increase the ultimate load of shallow footings by some up to 6.25 times for the current study conditions and variables. The performance of skirted footing depends upon the relative density of sand and on the skirt length to footing diameter ratio. Skirts are more beneficial in case of footings on loose sand than in case of medium and dense sand.

  2. Analytical and experimental bearing capacities of system scaffolds

    Institute of Scientific and Technical Information of China (English)

    Jui-lin PENG; Tsong YEN; Ching-chi KUO; Siu-lai CHAN

    2009-01-01

    We investigated the structural behavior and bearing capacity of system scaffolds. The research showed that the critical load of a system scaffold structure without diagonal braces is similar to that of a door-shaped steel scaffold structure. Joint stiffness between vertical props in system scaffolds can be defined based on a comparison between analytical and experimental results. When the number of scaffold stories increases, the critical loads of system scaffolds decrease. Diagonal braces markedly enhance the critical load of system scaffolds. The coupling joint position between vertical props should be kept away from story-to-story joints to prevent a reduction in critical loads. The critical load of a system scaffold decreases as the quantity of extended vertical props at the bottom of the structure increases. A large Christmas tree set up by system scaffolds under various loads was used as an example for analysis and to check the design of system scaffolds.

  3. Mechanism Research on the Improvement of Bearing Capacity of Single Pile by Pile-base Post Grouting Technique and Estimation of Bearing Capacity

    Directory of Open Access Journals (Sweden)

    Zhao Feng

    2015-01-01

    Full Text Available The slurry wall bored grouting has some defects. The pile-base post grouting technique can efficiently make up these defects and greatly improve the bearing capacity. Based on the pile-base post grouting technique and its process analysis, this paper carries out a detailed analysis about the improvement of mechanism of bearing capacity and mechanism of spherical expansion by the use of pile-base post grouting technique, as well as the estimation method of the bearing capacity of pile-base post grouting pile, which has a certain reference value for theoretical research and technical application of the technique.

  4. Contribution to Estimating Bearing Capacity of Pile in Clayey Soils

    Directory of Open Access Journals (Sweden)

    Drusa Marián

    2016-12-01

    Full Text Available The estimation of real geotechnical parameters is key factor for safe and economic design of geotechnical structures. One of these are pile foundations, which require proper design and evaluation due to accessing more deep foundation soil and because remediation work of not bearable piles or broken piles is a crucial operation. For this reason, geotechnical field testing like cone penetration test (CPT, standard penetration (SPT or dynamic penetration test (DP are realized in order to receive continuous information about soil strata. Comparing with rotary core drilling type of survey with sampling, these methods are more progressive. From engineering geologist point of view, it is more important to know geological characterization of locality but geotechnical engineers have more interest above the real geotechnical parameters of foundation soils. The role of engineering geologist cannot be underestimated because important geological processes in origin or during history can explain behaviour of a geological environment. In effort to streamline the survey, investigation by penetration tests is done as it is able to provide enough information for designers. This paper deals with actual trends in pile foundation design; because there are no new standards and usable standards are very old. Estimation of the bearing capacity of a single pile can be demonstrated on the example of determination of the cone factor Nk from CPT testing. Then results were compared with other common methods.

  5. Contribution to Estimating Bearing Capacity of Pile in Clayey Soils

    Science.gov (United States)

    Drusa, Marián; Gago, Filip; Vlček, Jozef

    2016-12-01

    The estimation of real geotechnical parameters is key factor for safe and economic design of geotechnical structures. One of these are pile foundations, which require proper design and evaluation due to accessing more deep foundation soil and because remediation work of not bearable piles or broken piles is a crucial operation. For this reason, geotechnical field testing like cone penetration test (CPT), standard penetration (SPT) or dynamic penetration test (DP) are realized in order to receive continuous information about soil strata. Comparing with rotary core drilling type of survey with sampling, these methods are more progressive. From engineering geologist point of view, it is more important to know geological characterization of locality but geotechnical engineers have more interest above the real geotechnical parameters of foundation soils. The role of engineering geologist cannot be underestimated because important geological processes in origin or during history can explain behaviour of a geological environment. In effort to streamline the survey, investigation by penetration tests is done as it is able to provide enough information for designers. This paper deals with actual trends in pile foundation design; because there are no new standards and usable standards are very old. Estimation of the bearing capacity of a single pile can be demonstrated on the example of determination of the cone factor Nk from CPT testing. Then results were compared with other common methods.

  6. Numerical analysis on bearing capacity of middle pylon caisson foundation of Taizhou Bridge

    Institute of Scientific and Technical Information of China (English)

    Wang Jun; Shao Guojian; Hu Feng; Gu Lijun

    2012-01-01

    Because of the computation difficulty of the beating capacity of large underwater caisson foundation on thick overburden layer ground, the geotechnieal software FLAC3D was utilized in the 3D numerical analysis on the bearing capacity of middle pylon foundation. From the computational results, it is concluded that the caisson foundation has a good bearing capacity on thick overburden layer ground and the beating capacity can be improved assuming that the soil near the area of basal comer is reinforced.

  7. Bearing Capacity Analyses for the Great Belt East Bridge Anchor Blocks

    DEFF Research Database (Denmark)

    Sørensen, Carsten Steen; Clausen, Carl J. Frimann; Andersen, Henrik

    1993-01-01

    This paper presents a comparison between different methods of bearing capacity analyses: Upper Bound Method. Limit Equilibrium Analysis and Finite Element Analysis. For the Great Belt East Bridge anchor blocks it was concluded that these methods of calculation agree within 5%. However, for cases...... where the bearing capacity is dominated by frictional materials, much higher differences should be expected....

  8. Effect of lobe profile on the load capacity of 2-lobe journal bearing

    Institute of Scientific and Technical Information of China (English)

    Stanislaw; STRZELECKI

    2001-01-01

    The rotors of turbogenerators operate in 2-lobe journal bearings. These bearings can bedesigned with the same or different profile of upper and bottom lobe, e.g. the upper lobe has cylin-drical and bottom one the offset profile. Shaping the bearing profile this way allows the variation ofstatic and dynamic characteristics of bearing. The static characteristics consist among others theload capacity of bearing which is very important parameter. The paper introduces the results ofcalculations of load capacity of 2-lobe journal bearing characterised by different profiles of upperand bottom lobe. The laminar, adiabatic oil flow in the bearing lubricating gap, parallel orientationof journal and bearing axis as well as the static equilibrium position of journal have been assumed.

  9. Analytical Model for the End-Bearing Capacity of Tapered Piles Using Cavity Expansion Theory

    Directory of Open Access Journals (Sweden)

    Suman Manandhar

    2012-01-01

    Full Text Available On the basis of evidence from model tests on increasing the end-bearing behavior of tapered piles at the load-settlement curve, this paper proposes an analytical spherical cavity expansion theory to evaluate the end-bearing capacity. The angle of tapering is inserted in the proposed model to evaluate the end-bearing capacity. The test results of the proposed model in different types of sands and different relative densities show good effects compared to conventional straight piles. The end-bearing capacity increases with increases in the tapering angle. The paper then propounds a model for prototypes and real-type pile tests which predicts and validates to evaluate the end-bearing capacity.

  10. Improvement of Bearing Capacity of Shallow Foundation on Geogrid Reinforced Silty Clay and Sand

    Directory of Open Access Journals (Sweden)

    P. K. Kolay

    2013-01-01

    Full Text Available The present study investigates the improvement in the bearing capacity of silty clay soil with thin sand layer on top and placing geogrids at different depths. Model tests were performed for a rectangular footing resting on top of the soil to establish the load versus settlement curves of unreinforced and reinforced soil system. The test results focus on the improvement in bearing capacity of silty clay and sand on unreinforced and reinforced soil system in non-dimensional form, that is, BCR. The results show that bearing capacity increases significantly with the increased number of geogrid layers. The bearing capacity for the soil increases with an average of 16.67% using one geogrid layer at interface of soils with equal to 0.667 and the bearing capacity increases with an average of 33.33% while using one geogrid in middle of sand layer with equal to 0.33. The improvement in bearing capacity for sand underlain silty clay maintaining and equal to 0.33; for two, three and four number geogrid layer were 44.44%, 61.11%, 72.22%, respectively. The finding of this research work may be useful to improve the bearing capacity of soil for shallow foundation and pavement design for similar type of soil available elsewhere.

  11. Parametric analysis of thermal effect on hydrostatic slipper bearing capacity of axial piston pump

    Institute of Scientific and Technical Information of China (English)

    汤何胜; 訚耀保; 张阳; 李晶

    2016-01-01

    Hydrostatic slipper was often used in friction bearing design, allowing improvement of the latter’s dynamic behavior. The influence of thermal effect on hydrostatic slipper bearing capacity of axial piston pump was investigated. A set of lumped parameter mathematical models were developed based on energy conservation law of slipper/ swash plate pair. The results show that thermal equilibrium clearance due to solid thermal deformation periodically changes with shaft rotational angle. The slipper bearing capacity increases dramatically with decreasing thermal equilibrium clearance. In order to improve the slipper bearing capacity, length-to-diameter ratio of fixed damper varies from 3.5 to 8.75 and radius ratio of slipper varies from 1.5 to 2.0. In addition, the higher slipper thermal conductivity is useful to improve slipper bearing capability, but the thermal equilibrium clearance is not compromised.

  12. Evaluation of Bearing Capacity of Strip Footing Using Random Layers Concept

    Directory of Open Access Journals (Sweden)

    Kawa Marek

    2015-09-01

    Full Text Available The paper deals with evaluation of bearing capacity of strip foundation on random purely cohesive soil. The approach proposed combines random field theory in the form of random layers with classical limit analysis and Monte Carlo simulation. For given realization of random the bearing capacity of strip footing is evaluated by employing the kinematic approach of yield design theory. The results in the form of histograms for both bearing capacity of footing as well as optimal depth of failure mechanism are obtained for different thickness of random layers. For zero and infinite thickness of random layer the values of depth of failure mechanism as well as bearing capacity assessment are derived in a closed form. Finally based on a sequence of Monte Carlo simulations the bearing capacity of strip footing corresponding to a certain probability of failure is estimated. While the mean value of the foundation bearing capacity increases with the thickness of the random layers, the ultimate load corresponding to a certain probability of failure appears to be a decreasing function of random layers thickness.

  13. Regressive approach for predicting bearing capacity of bored piles from cone penetration test data

    Directory of Open Access Journals (Sweden)

    Iyad S. Alkroosh

    2015-10-01

    Full Text Available In this study, the least square support vector machine (LSSVM algorithm was applied to predicting the bearing capacity of bored piles embedded in sand and mixed soils. Pile geometry and cone penetration test (CPT results were used as input variables for prediction of pile bearing capacity. The data used were collected from the existing literature and consisted of 50 case records. The application of LSSVM was carried out by dividing the data into three sets: a training set for learning the problem and obtaining a relationship between input variables and pile bearing capacity, and testing and validation sets for evaluation of the predictive and generalization ability of the obtained relationship. The predictions of pile bearing capacity by LSSVM were evaluated by comparing with experimental data and with those by traditional CPT-based methods and the gene expression programming (GEP model. It was found that the LSSVM performs well with coefficient of determination, mean, and standard deviation equivalent to 0.99, 1.03, and 0.08, respectively, for the testing set, and 1, 1.04, and 0.11, respectively, for the validation set. The low values of the calculated mean squared error and mean absolute error indicated that the LSSVM was accurate in predicting the pile bearing capacity. The results of comparison also showed that the proposed algorithm predicted the pile bearing capacity more accurately than the traditional methods including the GEP model.

  14. Influences of Taper Geometry Modified Oil-Grooves on Load Carrying Capacity of Crosshead Bearings

    Science.gov (United States)

    Kitahara, Tatsumi; Otsubo, Masaru; Nakahara, Daisuke

    The crosshead bearing in large two-stroke diesel engines operates under severe lubrication conditions, because the bearing oscillates within a small angle at a low speed and is always subject to a high downward load. The recent trend towards more compact engines with increased output raises the bearing specific load, thereby causing the lubrication severity to increase significantly. Thus it is very important to improve the load carrying capacity of the crosshead bearing. In the present study, experiments using a dynamically loaded bearing seizure test apparatus were carried out to clarify the influences of the clearance ratio and the oil-groove geometry on the load carrying capacity. The electrical resistance of the oil film was also measured to evaluate the extent of the oil film formation. The major results are: (1) A decrease in the clearance ratio is effective in enhancing squeeze action on the entirety of the bearing pads, thereby improving the load carrying capacity. When the clearance ratio becomes too low, however, the ability to form an adequate wedge film is degraded, causing the load carrying capacity to decrease; (2) A significant improvement in the load carrying capacity can be expected, because incorporating the taper geometry on both sides of the oil-groove promotes a thicker oil film; and (3) A taper geometry with a subtended length of 5 degrees and a taper angle of 0.1 degree produces the maximum load carrying capacity.

  15. Evaluation of Strip Footing Bearing Capacity Built on the Anthropogenic Embankment by Random Finite Element Method

    Science.gov (United States)

    Pieczynska-Kozlowska, Joanna

    2014-05-01

    One of a geotechnical problem in the area of Wroclaw is an anthropogenic embankment layer delaying to the depth of 4-5m, arising as a result of historical incidents. In such a case an assumption of bearing capacity of strip footing might be difficult. The standard solution is to use a deep foundation or foundation soil replacement. However both methods generate significant costs. In the present paper the authors focused their attention on the influence of anthropogenic embankment variability on bearing capacity. Soil parameters were defined on the basis of CPT test and modeled as 2D anisotropic random fields and the assumption of bearing capacity were made according deterministic finite element methods. Many repeated of the different realizations of random fields lead to stable expected value of bearing capacity. The algorithm used to estimate the bearing capacity of strip footing was the random finite element method (e.g. [1]). In traditional approach of bearing capacity the formula proposed by [2] is taken into account. qf = c'Nc + qNq + 0.5γBN- γ (1) where: qf is the ultimate bearing stress, cis the cohesion, qis the overburden load due to foundation embedment, γ is the soil unit weight, Bis the footing width, and Nc, Nq and Nγ are the bearing capacity factors. The method of evaluation the bearing capacity of strip footing based on finite element method incorporate five parameters: Young's modulus (E), Poisson's ratio (ν), dilation angle (ψ), cohesion (c), and friction angle (φ). In the present study E, ν and ψ are held constant while c and φ are randomized. Although the Young's modulus does not affect the bearing capacity it governs the initial elastic response of the soil. Plastic stress redistribution is accomplished using a viscoplastic algorithm merge with an elastic perfectly plastic (Mohr - Coulomb) failure criterion. In this paper a typical finite element mesh was assumed with 8-node elements consist in 50 columns and 20 rows. Footings width B

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

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  17. Bearing Capacity Estimation of Bridge Piles Using the Impulse Transient Response Method

    Directory of Open Access Journals (Sweden)

    Meng Ma

    2016-01-01

    Full Text Available A bearing capacity estimation method for bridge piles was developed. In this method, the pulse echo test was used to select the intact piles; the dynamic stiffness was obtained by the impulse transient response test. A total of 680 bridge piles were tested, and their capacities were estimated. Finally, core drilling analysis was used to check the reliability of this method. The results show that, for intact piles, an obvious positive correlation exits between the dynamic stiffness and bearing capacity of the piles. The core drilling analysis proved that the estimation method was reliable.

  18. Dynamic load testing on the bearing capacity of prestressed tubular concrete piles in soft ground

    Science.gov (United States)

    Yu, Chuang; Liu, Songyu

    2008-11-01

    Dynamic load testing (DLT) is a high strain test method for assessing pile performance. The shaft capacity of a driven PTC (prestressed tubular concrete) pile in marine soft ground will vary with time after installation. The DLT method has been successfully transferred to the testing of prestressed pipe piles in marine soft clay of Lianyungang area in China. DLT is investigated to determine the ultimate bearing capacity of single pile at different period after pile installation. The ultimate bearing capacity of single pile was founded to increase more than 70% during the inventing 3 months, which demonstrate the time effect of rigid pile bearing capacity in marine soft ground. Furthermore, the skin friction and axial force along the pile shaft are presented as well, which present the load transfer mechanism of pipe pile in soft clay. It shows the economy and efficiency of DLT method compared to static load testing method.

  19. Bearing Capacity Factors for Eccentrically Loaded Strip Footings Using Variational Analysis

    Directory of Open Access Journals (Sweden)

    Xinggao Li

    2013-01-01

    Full Text Available Bearing capacity factors for eccentrically loaded strip smooth footings on homogenous cohesive frictional material are deduced by the variational limit equilibrium method and by assuming general shear failure along continuous curved slip surface. From the calculated results, the effective width rule suggested by Meyerhof for bearing capacity factors due to cohesion of soil is justified, and the superposition principle of bearing capacity for eccentrically loaded strip smooth footings is derived together with the bearing capacity factors for cohesion and unit weight of soil. The two factors are represented by soil strength parameters and eccentricity of load. The bearing capacity factor related to unit weight for cohesionless soil is less than that for cohesive frictional soil. The reason for this discrepancy lies in the existence of the soil cohesion, for the shape of the critical rupture surface of footing soil depends on both soil strength parameters rather than on friction angle alone in the previous limit equilibrium solutions. The contact between footing and soil is decided by both the load and the mechanical properties of soil. Under conditions of higher eccentricity and less strength properties of soil, part of the footing will separate from the underlying soil.

  20. New design equations for estimation of ultimate bearing capacity of shallow foundations resting on rock masses

    Institute of Scientific and Technical Information of China (English)

    Amir H Alavi; Ehsan Sadrossadat

    2016-01-01

    Rock masses are commonly used as the underlying layer of important structures such as bridges, dams and transportation constructions. The success of a foundation design for such structures mainly depends on the accuracy of estimating the bearing capacity of rock beneath them. Several traditional numerical approaches are proposed for the estimation of the bearing capacity of foundations resting on rock masses to avoid performing elaborate and expensive experimental studies. Despite this fact, there still exists a serious need to develop more robust predictive models. This paper proposes new nonlinear prediction models for the ultimate bearing capacity of shallow foundations resting on non-fractured rock masses using a novel evolutionary computational approach, called linear genetic programming. A comprehen-sive set of rock socket, centrifuge rock socket, plate load and large-scaled footing load test results is used to develop the models. In order to verify the validity of the models, the sensitivity analysis is conducted and discussed. The results indicate that the proposed models accurately characterize the bearing capacity of shallow foundations. The correlation coefficients between the experimental and predicted bearing capacity values are equal to 0.95 and 0.96 for the best LGP models. Moreover, the derived models reach a notably better prediction performance than the traditional equations.

  1. Experimental Study on Post Grouting Bearing Capacity of Large Diameter Bored Piles

    Directory of Open Access Journals (Sweden)

    Wang Duanduan

    2015-01-01

    Full Text Available Post grouting can improve the inherent defects such as the formation of the mud cake at pile side and the sediment at pile end in the process of bored pile construction. Thus post grouting has been widely used in Engineering. The purpose of this paper is to research the influences of post grouting to pile bearing capacity more systematically and intuitively. Combined with the static load test of four test piles in Weihe River Bridge test area of new airport highway in Xi’an, the bearing capacity and settlement of routine piles and post grouting piles are comparatively analyzed. The test results show that under the same geological condition, post grouting can improve the properties of pile tip and pile shaft soil of bored piles significantly, enhance the ultimate resistance, improve the ultimate bearing capacity and reduce the pile tip settlement. Then post grouting can aim to optimize pile foundation.

  2. Reliability Analysis of Bearing Capacity of Large-Diameter Piles under Osterberg Test

    Directory of Open Access Journals (Sweden)

    Lei Nie

    2013-05-01

    Full Text Available This study gives the reliability analysis of bearing capacity of large-diameter piles under osterberg test. The limit state equation of dimensionless random variables is utilized in the reliability analysis of vertical bearing capacity of large-diameter piles based on Osterberg loading tests. And the reliability index and the resistance partial coefficient under the current specifications are calculated using calibration method. The results show: the reliable index of large-diameter piles is correlated with the load effect ratio and is smaller than the ordinary piles; resistance partial coefficient of 1.53 is proper in design of large-diameter piles.

  3. Lower-Bound Calculations of the Bearing Capacity of Eccentrically Loaded Footings in Cohesionless Soil

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

    2012-01-01

    Lower-bound calculations based on the finite element method are used to determine the bearing capacity of a strip foundation subjected to a vertical, eccentric load on cohesionless soil with varying surcharges. The soil is assumed perfectly plastic following the Mohr-Coulomb failure criterion....... The results are reported as tables and graphs showing the bearing capacity as a function of the eccentricity and surcharge. Normalised interaction diagrams in the vertical force versus moment plane have been produced. The results from the analysis are in reasonable agreement with existing methods for smaller...

  4. Ældre betonbroers bæreevne (Load bearing capacity of old concrete bridges)

    DEFF Research Database (Denmark)

    Nielsen, Anders

    1999-01-01

    was carried. - The other is a motor way bridge from 1939, which were reinforced 1991 with external steel plates on the areas of shear on the beams. Four beams were carried to our laboratory and load tested. The steel plates have doubled the load bearing capacity of the beams....

  5. The Bearing Capacity of Strip Footings in Cohesionless Soil Subject to Eccentric and Inclined Loads

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

    2014-01-01

    Lower bound calculations based on the finite element method is used to determine the bearing capacity of a strip foundation subjected to an inclined, eccentric load on cohesionless soil with varying surcharges and with friction angles 25, 30 and 35°. The soil is assumed perfectly plastic followin...

  6. The effect of loading rate on pile bearing capacity of saturated sand

    NARCIS (Netherlands)

    Archeewa, E.

    2005-01-01

    Pile load tests are commonly used by engineers to determine its bearing capacity. At present, there are three methods of pile load tests: the static, the dynamic and the quasi-static test. The static pile load test is done by applying an axial load on the pile with a long duration. The dynamic and q

  7. Stålplader gav dobbelt bæreevne (Steel plates doubled the load bearing capacity)

    DEFF Research Database (Denmark)

    Nielsen, Jan Broch

    1999-01-01

    Abstract from an examination of motor road bridge beams reinforced with steel plates on the sides and bottom. The plates doubled the load bearing capacity of the beams.......Abstract from an examination of motor road bridge beams reinforced with steel plates on the sides and bottom. The plates doubled the load bearing capacity of the beams....

  8. Influences of nonassociated flow rules on seismic bearing capacity factors of strip footing on soil slope by energy dissipation method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Seismic bearing capacity factors of a strip footing placed on soil slope were determined with both associated and nonassociated flow rules. Quasi-static representation of earthquake effects using a seismic coefficient concept was adopted for seismic bearing capacity calculations. A multi-wedge translational failure mechanism was used to obtain the seismic bearing capacity factors for different seismic coefficients and various inclined angles. Employing the associated flow rule, numerical results were compared with the published solutions. For bearing capacity factors related to cohesion and equivalent surcharge load, the maximum difference approximates 0.1%. However, the difference of bearing capacity factor related to unit weight is larger. With the two flow rules, the seismic bearing capacity factors were presented in the form of design charts for practical use. The results show that seismic bearing capacity factors related to the cohesion, the equivalent surcharge load and the unit weight increase greatly as the dilatancy angle increases, and that the nonassociated flow rule has important influences on the seismic bearing capacity.

  9. LOADING CAPACITY ANALYSIS OF THE MISALIGNED CONICAL-CYLINDRICAL BEARING WITH NON-NEWTONIAN LUBRICANTS

    Institute of Scientific and Technical Information of China (English)

    Yang Yongkuang; Yang Rongtai; Ho Minghsiung; Jheng Mingchang

    2004-01-01

    A novel numerical method to lubricate a conventional finite diameter conical(cylindrical bearing with a non-Newtonian lubricant, while adhering to the power-law model, is presented. The elastic deformation of bearing and varied viscosity of lubrication due to the pressure distribution of film thickness are also considered. Simulation results indicate that the normal load carrying capacity is more pronounced for higher values of flow behavior index n, higher eccentricity ratios and larger misalignment factors. It is found that the viscosity-pressure to the effect of lubricant viscosity is significant.

  10. The effect of manufacturing tolerances on the load carrying capacity of large diameter bearings

    Indian Academy of Sciences (India)

    Starvin M S; Manisekar K

    2015-09-01

    This paper deals with simplified 3D finite element (FE) analysis on the effect of manufacturing tolerances on the load carrying capacity of large diameter bearings based on Hertz theory. The nonlinear connector elements are used to model the rolling elements. This model enables us to evaluate the contact load on the rolling elements with relatively reduced calculation time. FE study has been carried out by allocating tolerance on balls and raceways using Monte Carlo simulation technique. The variation in dimension on balls is taken as per IS 2898-1976. A coding has been developed and employed for Monte Carlo simulation. Using the results of Monte Carlo simulation, tolerance has been assigned to the elements of large diameter bearing. From the results of finite element analysis, it is identified that analysis of large diameter bearing with tolerance on ball and raceway will lead to safe design.

  11. Seismic bearing capacity of strip footings on rock masses using the Hoek–Brown failure criterion

    Directory of Open Access Journals (Sweden)

    Amin Keshavarz

    2016-04-01

    Full Text Available In this paper, the bearing capacity of strip footings on rock masses has been studied in the seismic case. The stress characteristics or slip line method was used for analysis. The problem was analyzed in the plane strain condition using the Hoek–Brown failure criterion. First, the equilibrium equations along the stress characteristics were obtained and the rock failure criterion was applied. Then, the equations were solved using the finite difference method. A computer code has been provided for analysis. Given the footing and rock parameters, the code can calculate the stress characteristics network and obtain the stress distribution under the footing. The seismic effects have been applied as the horizontal and vertical pseudo-static coefficients. The results of this paper are very close to those of the other studies. The seismic bearing capacity of weightless rock masses can be obtained using the proposed equations and graphs without calculating the whole stress characteristics network.

  12. Comparison of standard penetration test methods on bearing capacity of shallow foundations on sand

    Directory of Open Access Journals (Sweden)

    Scott Bernard Akpila

    2013-03-01

    Full Text Available A comparison of standard penetration test methods on bearing capacity analysis of shallow foundations on sand using analytical methods proposed by Parry, Meyerhof and modified Meyerhof has been carried out. The results showed three bound limits; upper, middle and lower bonds of net allowable bearing capacity, qn(a, values for isolated pad foundations placed on sand. Perry’s method gave higher values followed by the modified Meyerhof’s method and lastly by the Meyerhof’s method. Generally, qn(a showed a decreasing trend as foundation breadth and depth increased. The qn(a of modified Meyerhof’s model can be approximated by applying a factor of safety, FS, of 3.25 on Perry’s model. Similarly, qn(a of Meyerhof’s model can be approximated by applying a factor of safety, FS, of 2.0 on the modified Meyerhof’s model.

  13. Bearing Capacity of High Density Polyethylene (HDPE Reinforced Sand Using Plate Load Test

    Directory of Open Access Journals (Sweden)

    Er. Aly K

    2015-06-01

    Full Text Available The work presented here is a study to examine the improvement in bearing capacity of coastal sand of Trivandrum, Kerala, India using high density polyethylene (HDPE /woven fabric as reinforcement in discrete layers. The bearing capacity was evaluated using plate load test. The effect of reinforcement configurations like sheet reinforcement (sanded with adhesive, with adhesive and sheet alone and strip reinforcement (single and grid pattern are investigated. The test parameters chosen for the present study are, depth of topmost layer of reinforcement layer below footing, compacted density and number of layers of reinforcement etc. From the tests, it has been observed that sheet reinforcement is more effective than sheet sanded with adhesive and strip reinforcements. It is found that the synthetic adhesive gives no binding action at the interface of the reinforcement and soil. But it is to be noted that the sheet with adhesive dried has a marked influence on the bearing capacity especially at lower densities. The strip reinforcements in single pattern is considered to be a favorable choice for minimum reinforcement. The strip reinforcement in single or grid pattern gives sufficient improvement in strength.

  14. BEARING CAPACITY OF A HORIZONTALLY LOADED SINGLE PILE SUPPORT WITH SLEEPERS

    Directory of Open Access Journals (Sweden)

    Buslov Anatoliy Semenovich

    2015-09-01

    Full Text Available The supports of a overhead wiring used in transport take up substantial loads both because of wires and constructions holding them and wind, dynamic and other extraordinary impacts. In case of using single-member piles a question about their stability appears. For this reason different sleepers constructions are used. In order to improve the bearing capacity of horizontally loaded single pile supports of the contact systems used in urban, road and rail transport, power lines, etc.., it is recommended to use sleepers as horizontally laid under the ground in the depth of support beams. The calculation methods for different support sleepers of different lengths and cross sections are not well investigated. The proposed calculation method allows determining the carrying capacity of horizontally loaded bearings with soil pieces of different structural dimensions and their location in the soil, which allows choosing the best option for cost and material consumption. The calculations offered by the authors prove the efficiency of sleepers use in order to increase the bearing capacity of horizontally loaded piles and the possibility to chose their size.

  15. The influence of selecting the correlation model on soil parameters and bearing capacity

    Science.gov (United States)

    Pieczynska-Kozlowska, Joanna M.

    2016-04-01

    Consideration of soil spatial variability in the geotechnical design is still marginalized. The design process is based on taking the average parameters, which often results the oversize of geotechnical constructions. This procedure works until there are no geotechnical design problems. In most cases, geotechnical constructions represent a small percentage of the total investment so effects lacking developed of optimization procedures. If the optimization is needed requires the most accurate mapping of the soil. The basic background for statistical interpretation of soil spatially variables are Cone Penetration Tests, which represents variable nature of the soil with depth. Assuming the soil structure as a spatially random variable can be applied by description based on random fields. Field parameters are the probability distribution and correlation model dependent of a scale of fluctuation estimated from CPT. The main goal of this study is to contribute to the understanding on how the choice of correlation model affects random soil properties and for example shallow foundation bearing capacity. The study is particularly focused on scale of fluctuation as related to the reduction of bearing capacity. Scale of fluctuation were estimated using two effective methods: Vanmarcke and Rice. Soil properties were analyzed from 12 Cone Penetration Tests distributed throughout the regions of Świebodzice (Lower Silesia, Poland). While the project was developed in hilly terrain the macrolevelling were taken involving the displacement of native soil mass to form a working platform for shallow foundation. The construction of embankment has been tested by cone resistance tests to determine the parameters for the design. The procedure adopted to this study include the modeling soil variability from the CPT results and calculate the bearing capacity of shallow foundation using random finite element method and different correlation models. The aim of study was to answer questions

  16. Bear

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The famous physicist made for his scholars this riddle. A fellow encountered a bear in a wasteland. There was nobody else there. Both were frightened and ran away. Fellow to the north, bear to the west. Suddenly the fellow stopped, aimed his gun to the south and shot the bear. What colour was the bear?

  17. Effect of slope height and horizontal forces on the bearing capacity of strip footings near slopes in cohesionless soil

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

    2016-01-01

    , and in such cases the bearing capacity of the footing cannot be found using the existing methods. The present work comprises finite element based upper- and lower-bound calculations, using the geotechnical software OptumG2 to investigate the effect of the slope height and horizontal forces on the total bearing...

  18. Finite Element Analysis of the Effect on Edge Distance of the Tensile Bearing Capacity of Embedded Hanging Parts

    OpenAIRE

    Meng Xian Hong; Liu Wei

    2016-01-01

    In order to explore the trend of tensile bearing capacity of embedded hanging parts when change the edge distance. Based on the finite element analysis software ABAQUS, the four simulation model was established. The buried depth and strength of concrete remain unchanged, but the edge distance was gradient change. By the load - displacement curve of every model known, the greater the edge distance, the greater the bearing capacity. When the edge distance reaches 1.5 times buried depth, the eff...

  19. Random analysis of bearing capacity of square footing using the LAS procedure

    Directory of Open Access Journals (Sweden)

    Kawa Marek

    2016-09-01

    Full Text Available In the present paper, a three-dimensional problem of bearing capacity of square footing on random soil medium is analyzed. The random fields of strength parameters c and φ are generated using LAS procedure (Local Average Subdivision, Fenton and Vanmarcke 1990. The procedure used is re-implemented by the authors in Mathematica environment in order to combine it with commercial program. Since the procedure is still tested the random filed has been assumed as one-dimensional: the strength properties of soil are random in vertical direction only.

  20. Bearing Capacity of Footings on Thin Layer of Sand on Soft Cohesive Soil

    DEFF Research Database (Denmark)

    Philipsen, J.; Sørensen, Carsten S.

    2004-01-01

    This paper contains the results of some numerical calculations performed with the aim to determine the bearing capacities of footings placed on a thin layer of sand underlain by soft cohesive soil. During the last 30-35 years different analytical and empirical calculation methods for this situation...... have been presented. These methods often give widely different results. Therefore, in the light of the numerical calculations, the analytical and empirical calculation methods have been evaluated and compared. The calculations have been carried out based on results from well documented and well...

  1. VIS-NIR, SWIR and LWIR Imagery for Estimation of Ground Bearing Capacity

    Directory of Open Access Journals (Sweden)

    Roemi Fernández

    2015-06-01

    Full Text Available Ground bearing capacity has become a relevant concept for site-specific management that aims to protect soil from the compaction and the rutting produced by the indiscriminate use of agricultural and forestry machines. Nevertheless, commonly known techniques for its estimation are cumbersome and time-consuming. In order to alleviate these difficulties, this paper introduces an innovative sensory system based on Visible-Near InfraRed (VIS-NIR, Short-Wave InfraRed (SWIR and Long-Wave InfraRed (LWIR imagery and a sequential algorithm that combines a registration procedure, a multi-class SVM classifier, a K-means clustering and a linear regression for estimating the ground bearing capacity. To evaluate the feasibility and capabilities of the presented approach, several experimental tests were carried out in a sandy-loam terrain. The proposed solution offers notable benefits such as its non-invasiveness to the soil, its spatial coverage without the need for exhaustive manual measurements and its real time operation. Therefore, it can be very useful in decision making processes that tend to reduce ground damage during agricultural and forestry operations.

  2. Experimental research on ultimate bearing capacity of grouted-round-steel-tube N-joint

    Institute of Scientific and Technical Information of China (English)

    ZHENG Wen-zhong; LIU Xu-dong; ZHANG Ge-ming; ZHANG Bo-yi

    2007-01-01

    As an important structural member in self-supporting concrete floor during construction, encased steel truss-concrete composite beam has brilliant prospect in outer-jacketing structures for adding stories or mega frame structures. Compared with encased angle truss, encased round steel tube truss can facilitate layout of itself in column and facilitate layout and anchorage of prestressed reinforcement placed horizontally. N-joint is wildly used in encased steel truss. For cave-in failure easily occurs in hollow steel-tube joint, the idea that the chord is grouted to increase cave-in bearing capacity of hollow tube is proposed. Test results of 8 grouted-roundsteel-tube N-joints from the beginning of loading to failure are reported. Mechanical property and failure mode of this kind of truss joint are analyzed, and the formulas of ultimate bearing capacity of the joint corresponding to different failure modes are established. All these can provide basic data for spreading encased steel truss-concrete composite beam.

  3. Numerical simulation of the influence of soil core on the bearing capacity of pipe pile

    Directory of Open Access Journals (Sweden)

    G.Ya. Bulatov

    2010-03-01

    Full Text Available The cost of the foundation can be up to 20-30% of the total building cost. Reducing consumption of materials and quality selection of the required characteristics of the pile can reduce both the estimated cost and time of work.In terms of compact construction and the high land prices the most relevant is high-rise building. But it is hard to build in soft ground conditions (for example, in St. Petersburg. The situation is complicated by insufficiently explored methods of selection and design of piles (especially steel-tube piles for specific cases of construction, as well as by the absence of regulatory documents related to the high-performance technology.The article considers the clarification methods for calculating the bearing capacity of tubular steel piles. An additional contribution of soil core to the overall bearing capacity due to accounting an effect of its "natural" selflocking in the cavity of the steel pipe is considered.The conclusions about the effectiveness of the piles, depending on different initial parameters are made.

  4. VIS-NIR, SWIR and LWIR Imagery for Estimation of Ground Bearing Capacity

    Science.gov (United States)

    Fernández, Roemi; Montes, Héctor; Salinas, Carlota

    2015-01-01

    Ground bearing capacity has become a relevant concept for site-specific management that aims to protect soil from the compaction and the rutting produced by the indiscriminate use of agricultural and forestry machines. Nevertheless, commonly known techniques for its estimation are cumbersome and time-consuming. In order to alleviate these difficulties, this paper introduces an innovative sensory system based on Visible-Near InfraRed (VIS-NIR), Short-Wave InfraRed (SWIR) and Long-Wave InfraRed (LWIR) imagery and a sequential algorithm that combines a registration procedure, a multi-class SVM classifier, a K-means clustering and a linear regression for estimating the ground bearing capacity. To evaluate the feasibility and capabilities of the presented approach, several experimental tests were carried out in a sandy-loam terrain. The proposed solution offers notable benefits such as its non-invasiveness to the soil, its spatial coverage without the need for exhaustive manual measurements and its real time operation. Therefore, it can be very useful in decision making processes that tend to reduce ground damage during agricultural and forestry operations. PMID:26083227

  5. Effect of Bearing Capacity of Strip Footing on Reinforced Double Layer Soil System with Fly ash Stabilized Clayey Soil

    Directory of Open Access Journals (Sweden)

    Love Sharma

    2015-08-01

    Full Text Available This research was performed to investigate the effect of bearing capacity of strip footing on geogrid reinforced sand overlay on stabilized expansive soil (i.e. double layer soil system and check the different parameters contributing to their performance using laboratory model tank tests. The parameters investigated in this study include H/B (thickness of top sandy layer to width of footing u/B (location of the 1st layer of reinforcement to width of footing, h/B (vertical spacing between consecutive geogrid layers to width of footing, b/B (length of the geogrid layer to width of footing. The effect of different H/B ratios and geogrid reinforcement N values on the bearing capacity ration (BCR and settlement reduction ratio (SRR were also investigated. The results show that bearing capacity increases significantly with increasing the H/B ratio as well as number of geogrid layers. The bearing capacity for the soil increases with an average of 12.35% using H/B equal to0.5 and the bearing capacity increases with an average of 35.76%, 75.56% & 230.83% while using H/B equal to 1.0, 1.5 & 2.0. It also found that the use of sandy layers over flyash mixed clayey soil has a considerable effect on the bearing capacity characteristics and the use of geogrid layers in the granular overlay has remarkable effect on Bearing capacity ratio (BCR & Settlement reduction ratio (SRR.

  6. Analysis of Bearing Capacity of Suction Bucket Foundation Subjected to Horizontal and Moment Loadings

    Directory of Open Access Journals (Sweden)

    W.U. Ke

    2013-07-01

    Full Text Available The suction bucket foundation is not only supporting the vertical loading such as the sea platform and weight itself, but also subjecting to horizontal and moment loading due to wind and wave. The response of bucket foundation to combined Horizontal (H and Moment (M loading has been studied using 3D finite element analysis Then the proposed method is numerically implemented in the framework of the general-purpose FEM software ABAQUS. Relationship curve between the coefficient of ultimate bearing capacity and displacement is obtained by the application of load-displacement controlled method in homogeneous soft foundation the failure envelope of foundation in the M-H is obtained by the application of swipe testing. The behavior is explained using upper bound plasticity mechanisms suggested by the soil deformation mechanisms observed in the finite element analysis. The numerical results computed by the proposed method will be helpful in engineering practices.

  7. Ultimate bearing capacity and settlement of coal pillar sub-strata

    Energy Technology Data Exchange (ETDEWEB)

    Chugh, Y.P.; Pula, O.; Pytel, W.M. (Southern Illinois University, Carbondale, IL (USA). Dept. of Mining Engineering)

    1990-06-01

    This paper develops a rational approach for design of coal pillars under weak floor strata conditions considering ultimate bearing capacity (UBC) as well as pillar settlement. An approximate solution is presented for estimation of UBC for a shallow foundation on a two-layered rock system with consideration of both cohesion ({ital c}) and ({phi}) for both layers. Similarly, deformability underneath a full-size pillar is estimated from deformability calculated from plate loading tests. The effect of adjacent pillars on UBC and deformability of coal pillars in a panel is considered using foundation engineering analysis techniques. The design of pillars based on limiting settlements considers both differential settlements as well as mean settlement of pillar in a panel. An attempt is made to validate the proposed design approach based on field data and observations at an Illinois mine. 37 refs., 12 figs., 1 tab.

  8. 3D Bearing Capacity of Structured Cells Supported on Cohesive Soil: Simplified Analysis Method

    Directory of Open Access Journals (Sweden)

    Martínez-Galván Sergio Antonio

    2013-06-01

    Full Text Available In this paper a simplified analysis method to compute the bearing capacity of structured cell foundations subjected to vertical loading and supported in soft cohesive soil is proposed. A structured cell is comprised by a top concrete slab structurally connected to concrete external walls that enclose the natural soil. Contrary to a box foundation it does not include a bottom slab and hence, the soil within the walls becomes an important component of the structured cell. This simplified method considers the three-dimensional geometry of the cell, the undrained shear strength of cohesive soils and the existence of structural continuity between the top concrete slab and the surrounding walls, along the walls themselves and the walls structural joints. The method was developed from results of numerical-parametric analyses, from which it was found that structured cells fail according to a punching-type mechanism.

  9. [Change of resource environmental bearing capacity of Beijing-Tianjin-Hebei region and its driving factors].

    Science.gov (United States)

    Guo, Ke; Wang, Li-qun

    2015-12-01

    Based on the evaluation index system established for measuring the resource environmental bearing capacity (REBC), this paper measured the REBC of Beijing-Tianjin-Hebei region by applying the state space model and analyzed their driving factors by using the Tobit model. The results showed that the REBC of Beijing-Tianjin-Hebei region was in the available state and at the rising stage as well during 2000-2012. The social economic growth had great pressure on the resources and environment. The bearing ratios of the REBCs of Beijing, Tianjin and Hebei all presented a U curve and located at low levels, which meant that there was high REBC potential in these regions. Both of the permanent population and the urban residents 'Engel' s coefficient were the influence factors of the REBC of Beijing-Tianjin-Hebei region. The population problem was likely to become the bottleneck to restrict the regional social and economic development, and also threaten the resources and environment. The specific driving factors of the REBC were different in Beijing, Tianjin and Hebei. For example, energy consumption per unit of GDP only had significant impact on Tianjin. At last, the paper proposed that the three regions should complement each other in resources and environment, social development, and economic structure, also the REBC should be taken a reference in decision and policy making.

  10. Approximate Solution of Oil Film Load-carrying Capacity of Turbulent Journal Bearing with Couple Stress Flow

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yongfang; WU Peng; GUO Bo; L Yanjun; LIU Fuxi; YU Yingtian

    2015-01-01

    The instability of the rotor dynamic system supported by oil journal bearing is encountered frequently, such as the half-speed whirl of the rotor, which is caused by oil film lubricant with nonlinearity. Currently, more attention is paid to the physical characteristics of oil film due to an oil-lubricated journal bearing being the important supporting component of the bearing-rotor systems and its nonlinear nature. In order to analyze the lubrication characteristics of journal bearings efficiently and save computational efforts, an approximate solution of nonlinear oil film forces of a finite length turbulent journal bearing with couple stress flow is proposed based on Sommerfeld and Ocvirk numbers. Reynolds equation in lubrication of a finite length turbulent journal bearing is solved based on multi-parametric principle. Load-carrying capacity of nonlinear oil film is obtained, and the results obtained by different methods are compared. The validation of the proposed method is verified, meanwhile, the relationships of load-carrying capacity versus eccentricity ratio and width-to-diameter ratio under turbulent and couple stress working conditions are analyzed. The numerical results show that both couple stress flow and eccentricity ratio have obvious influence on oil film pressure distribution, and the proposed method approximates the load-carrying capacity of turbulent journal bearings efficiently with various width-to-diameter ratios. This research proposes an approximate solution of oil film load-carrying capacity of turbulent journal bearings with different width-to-diameter ratios, which are suitable for high eccentricity ratios and heavy loads.

  11. Effects of design parameters on carrying capacity of a double-row tapered roller slewing bearing used in wind turbine

    Directory of Open Access Journals (Sweden)

    Yunfeng Li

    2016-07-01

    Full Text Available Mechanical model with detailed design parameters of a rotor slewing bearing with the structure type of double-row tapered roller for supporting the rotor of the wind turbine was presented. The internal geometrical relationships of the rotor slewing bearing were established in the Cartesian coordinate system. The elastic contact deformations between each tapered roller and the raceways were expressed through the geometrical transformation. The mechanical model was established using the equilibrium relations in the rotor slewing bearing. The safety factor and the fatigue life which represents, respectively, the ability of resisting the rolling contact plastic deformation failure and the rolling contact fatigue failure of the rotor slewing bearing were obtained based on the solution of the mechanical model. Effects of the detailed design parameters such as axial clearance, contact angle, and roller semi-cone angle on the carrying capacity of the rotor slewing bearing were analyzed. The results show that right amount of small negative axial clearance, increase in contact angle, and decrease in roller semi-cone angle are advantageous for enhancing the carrying capacity of the rotor slewing bearing. This provides the basis for the reasonable value selection of the design parameters of the double-row tapered roller slewing bearing for supporting the rotor of the wind turbine.

  12. DESIGN OF STRUCTURAL ELEMENTS IN THE EVENT OF THE PRE-SET RELIABILITY, REGULAR LOAD AND BEARING CAPACITY DISTRIBUTION

    Directory of Open Access Journals (Sweden)

    Tamrazyan Ashot Georgievich

    2012-10-01

    Full Text Available Accurate and adequate description of external influences and of the bearing capacity of the structural material requires the employment of the probability theory methods. In this regard, the characteristic that describes the probability of failure-free operation is required. The characteristic of reliability means that the maximum stress caused by the action of the load will not exceed the bearing capacity. In this paper, the author presents a solution to the problem of calculation of structures, namely, the identification of reliability of pre-set design parameters, in particular, cross-sectional dimensions. If the load distribution pattern is available, employment of the regularities of distributed functions make it possible to find the pattern of distribution of maximum stresses over the structure. Similarly, we can proceed to the design of structures of pre-set rigidity, reliability and stability in the case of regular load distribution. We consider the element of design (a monolithic concrete slab, maximum stress S which depends linearly on load q. Within a pre-set period of time, the probability will not exceed the values according to the Poisson law. The analysis demonstrates that the variability of the bearing capacity produces a stronger effect on relative sizes of cross sections of a slab than the variability of loads. It is therefore particularly important to reduce the coefficient of variation of the load capacity. One of the methods contemplates the truncation of the bearing capacity distribution by pre-culling the construction material.

  13. Effect of slope height and horizontal forces on the bearing capacity of strip footings near slopes in cohesionless soil

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

    2016-01-01

    The problem of determining the bearing capacity of a strip foundation located near a slope of infinite height has been dealt with by several authors. Very often in practical problems the slope is of limited height, and furthermore the resulting load may be inclined at an angle to the horizontal, ...

  14. Experimental research on the creep behavior and bearing capacity of repeatedly prestressed concrete beam

    Institute of Scientific and Technical Information of China (English)

    SHAO Xudong; LI Lifeng; YANG Jianjun

    2007-01-01

    In the prestress tensioning process of medium or short span prestressed concrete beam bridges,there are always many serious problems,such as the camber of straight beam being too large,curved beam going crosswise,and columns of rigid beam bridge cracking,that can be commonly seen because of its greater additional stress in prestressing.To solve the above problems,a new concept of repeatedly prestressed bridge structure was innovatively proposed in this work.It was proved,through theoretical and experimental comparison between this new structure and the traditional prestressed structure,that the application of repeated prestressing technology can greatly improve the mechanical and deformational performance of the low height beam during construction and long-term use.Furthermore,a kind of computational formula to calculate creep strain and deformation due to repeated prestressing in terms of time t was derived in this paper and the bearing capacity of this new structure has been tested.Finally,the work concludes that there is a bright application prospect for this new structure for medium and short span prestressed beam bridges to control deformations.

  15. Development of REBCO HTS Magnet of Magnetic Bearing for Large Capacity Flywheel Energy Storage System

    Science.gov (United States)

    Mukoyama, Shinichi; Matsuoka, Taro; Furukawa, Makoto; Nakao, Kengo; Nagashima, Ken; Ogata, Masafumi; Yamashita, Tomohisa; Hasegawa, Hitoshi; Yoshizawa, Kazuhiro; Arai, Yuuki; Miyazaki, Kazuki; Horiuchi, Shinichi; Maeda, Tadakazu; Shimizu, Hideki

    A flywheel energy storage system (FESS) is a promising electrical storage system that moderates fluctuation of electrical power from renewable energy sources. The FESS can charge and discharge the surplus electrical power repetitively with the rotating energy. Particularly, the FESS that utilizes a high temperature superconducting magnetic bearing (HTS bearing) is lower loss than conventional FESS that has mechanical bearing, and has property of longer life operation than secondary batteries. The HTS bearing consists of a HTS bulk and double-pancake coils used 2nd generation REBCO wires. In the development, the HTS double-pancake coils were fabricated and were provided for a levitation test to verify the possibility of the HTS bearing. We successfully confirmed the magnetic field was achieved to design value, and levitation force in the configuration of one YBCO bulk and five double pan-cake coils was obtained to a satisfactory force of 39.2 kN (4 tons).

  16. Thermal shaft effects on load-carrying capacity of a fully coupled, variable-properties cryogenic journal bearing

    Science.gov (United States)

    Braun, M. J.; Wheeler, R. L., III; Hendricks, R. C.

    1986-01-01

    The purpose of this work was to perform a rather complete analysis for a cryogenic (oxygen) journal bearing. The Reynolds equation required coupling and simultaneous solution with the fluid energy equation. To correctly account for the changes in the fluid viscosity, the fluid energy equation was coupled with the shaft and bearing heat conduction energy equations. The effects of pressure and temperature on the density, viscosity, and load-carrying capacity were further discussed as analysis parameters, with respect to relative eccentricity and the angular velocity. The isothermal fluid case and the adiabatic fluid case represented the limiting boundaries. The discussion was further extrapolated to study the Sommerfeld number dependency on the fluid Nusselt number and its consequence on possible total loss of load-carrying capacity and/or seizure (catastrophic failure).

  17. Analysis of Theoretical Basis of the Bearing Capacity Study from the Properties of the Bearing Capacity%从承载力的属性分析承载力研究的理论基础

    Institute of Scientific and Technical Information of China (English)

    张宏亮; 何波

    2013-01-01

    This paper argues that the study on the issue of the bearing capacity should focus on its properties. From the perspective of economics, there are three economical characters, namely, there is long-term and short term;the bearing capacity can be measured by the marginal output effect among macro factors;and there is action and reaction. From the perspective of physics, carrying objects include structure, components or materials, and their physical attribute can map the properties of the generalized bearing objects. Abandoningthecontroloverstatisticalphysics,andusingtheotherbranchofphysicsmightbemorebeneifcialtocarryingcapacityusing econophysics to build study theory. Factor mobility bears much resemblance with the motion of objects on the physical space. And research foundation of bearing capacity established by factor-factor relation can be made the detail analysis by using generalized method of physics. In conclusion, resources and environment comprehensive bearing capacity of a certain area can be studied via building the model of the external relations of production and internal physical relationship model.%承载力问题的研究,应该回归到对承载力本身的属性研究上来。从经济学出发,承载力有三点经济属性,一是有长期与短期之分,二是可由宏观要素间的边际产出效果来衡量,三是有作用力与反作用力。从物理学出发,一是结构、构件或材料即为承载对象,其物理属性可以映射为广义承载对象的属性;二是放开对统计物理的限定,利用其他物理分支可能更有利于承载力利用经济物理来构建研究理论;三是要素的流动与物理空间上物体的运动具有很大的相似性,以要素关系建立起来的承载力研究基础,也可以通过广义物理的方法来进行细节化的分析。总之,一定区域的资源环境综合承载力,可以通过构建外在的生产关系模型和内在的物理关系模型来研究。

  18. Influence of particles on the loading capacity and the temperature rise of water film in Ultra-high speed hybrid bearing

    Science.gov (United States)

    Zhu, Aibin; Li, Pei; Zhang, Yefan; Chen, Wei; Yuan, Xiaoyang

    2015-04-01

    Ultra-high speed machining technology enables high efficiency, high precision and high integrity of machined surface. Previous researches of hybrid bearing rarely consider influences of solid particles in lubricant and ultra-high speed of hybrid bearing, which cannot be ignored under the high speed and micro-space conditions of ultra-high speed water-lubricated hybrid bearing. Considering the impact of solid particles in lubricant, turbulence and temperature viscosity effects of lubricant, the influences of particles on pressure distribution, loading capacity and the temperature rise of the lubricant film with four-step-cavity ultra-high speed water-lubricated hybrid bearing are presented in the paper. The results show that loading capacity of the hybrid bearing can be affected by changing the viscosity of the lubricant, and large particles can improve the bearing loading capacity higher. The impact of water film temperature rise produced by solid particles in lubricant is related with particle diameter and minimum film thickness. Compared with the soft particles, hard particles cause the more increasing of water film temperature rise and loading capacity. When the speed of hybrid bearing increases, the impact of solid particles on hybrid bearing becomes increasingly apparent, especially for ultra-high speed water-lubricated hybrid bearing. This research presents influences of solid particles on the loading capacity and the temperature rise of water film in ultra-high speed hybrid bearings, the research conclusions provide a new method to evaluate the influence of solid particles in lubricant of ultra-high speed water-lubricated hybrid bearing, which is important to performance calculation of ultra-high speed hybrid bearings, design of filtration system, and safe operation of ultra-high speed hybrid bearings.

  19. Influence of Particles on the Loading Capacity and the Temperature Rise of Water Film in Ultra-high Speed Hybrid Bearing

    Institute of Scientific and Technical Information of China (English)

    ZHU Aibin; LI Pei; ZHANG Yefan; CHEN Wei; YUAN Xiaoyang

    2015-01-01

    Ultra-high speed machining technology enables high efficiency, high precision and high integrity of machined surface. Previous researches of hybrid bearing rarely consider influences of solid particles in lubricant and ultra-high speed of hybrid bearing, which cannot be ignored under the high speed and micro-space conditions of ultra-high speed water-lubricated hybrid bearing. Considering the impact of solid particles in lubricant, turbulence and temperature viscosity effects of lubricant, the influences of particles on pressure distribution, loading capacity and the temperature rise of the lubricant film with four-step-cavity ultra-high speed water-lubricated hybrid bearing are presented in the paper. The results show that loading capacity of the hybrid bearing can be affected by changing the viscosity of the lubricant, and large particles can improve the bearing loading capacity higher. The impact of water film temperature rise produced by solid particles in lubricant is related with particle diameter and minimum film thickness. Compared with the soft particles, hard particles cause the more increasing of water film temperature rise and loading capacity. When the speed of hybrid bearing increases, the impact of solid particles on hybrid bearing becomes increasingly apparent, especially for ultra-high speed water-lubricated hybrid bearing. This research presents influences of solid particles on the loading capacity and the temperature rise of water film in ultra-high speed hybrid bearings, the research conclusions provide a new method to evaluate the influence of solid particles in lubricant of ultra-high speed water-lubricated hybrid bearing, which is important to performance calculation of ultra-high speed hybrid bearings, design of filtration system, and safe operation of ultra-high speed hybrid bearings.

  20. Progressive collapse resisting capacity of reinforced concrete load bearing wall structures

    Institute of Scientific and Technical Information of China (English)

    Alireza Rahai; Alireza Shahin; Farzad Hatami

    2015-01-01

    Reinforced concrete (RC) load bearing wall is widely used in high-rise and mid-rise buildings. Due to the number of walls in plan and reduction in lateral force portion, this system is not only stronger against earthquakes, but also more economical. The effect of progressive collapse caused by removal of load bearing elements, in various positions in plan and stories of the RC load bearing wall system was evaluated by nonlinear dynamic and static analyses. For this purpose, three-dimensional model of 10-story structure was selected. The analysis results indicated stability, strength and stiffness of the RC load-bearing wall system against progressive collapse. It was observed that the most critical condition for removal of load bearing walls was the instantaneous removal of the surrounding walls located at the corners of the building where the sections of the load bearing elements were changed. In this case, the maximum vertical displacement was limited to 6.3 mm and the structure failed after applying the load of 10 times the axial load bored by removed elements. Comparison between the results of the nonlinear dynamic and static analyses demonstrated that the “load factor” parameter was a reasonable criterion to evaluate the progressive collapse potential of the structure.

  1. Hertzian Load-bearing Capacity of Hybrid and Nano-hybrid Resin Composites Stored Dry and Wet

    Directory of Open Access Journals (Sweden)

    Farmani S

    2016-03-01

    Full Text Available Statement of Problem: Hertzian indentation test has been proven to be an efficient and reliable alternative upon Vickers hardness test. This method has been used to test dental ceramics, amalgams, glass ionomers and luting cements.There is limited published information about the load-bearing capacity of resin composites using Hertizian indentation test. Objectives: To investigate the load-bearing capacity of hybrid and nano-hybrid resin composites stored dry or wet up to 30 days, using Hertzian indentation test. Materials and Methods: Three resin composites were used: two nano-hybrids (Filtek Supreme, and Luna and one hybrid, (Rok. A total of 108 disc-shaped specimens (1mm thick x 10 mm diameter were prepared using polyethylene mould. The specimens of each material were randomly divided into 6 groups of 6 (n=6 and stored at 370C either in distilled water or dry for 1, 7 and 30 days. The specimens were tested using Hertzian jig aligned in the universal testing machine. The specimen was placed on the top of a disc-shaped substrate. The load was applied at the center of each specimen and the load at the first crack was recorded. Data were analyzed by ANOVA, Tukey’sand student’s t-test using SPSS version 18.0. Results: Three-way ANOVA showed a significant interaction between all the factors (p = .0001. The load bearing capacity of almost all materials reduced significantly in the wet condition in comparison with the dry condition (p = .0001. After seven days of immersion in distilled water, Filtek Supreme had significantly lower values than those of Rok and Luna, there was no significant differences between materials in the dry condition. Conclusions:In contrast to dry condition, the load-bearing capacity of specimens stored in distilled water decreased significantly over the 30 days of immersion. The load bearing capacity of nano-hybrid composites tested in this study was shown to be comparable with that of the hybrid composite.

  2. ANALYSIS OF SUFFICIENCY OF THE BEARING CAPACITY OF BUILDING STRUCTURES OF OPERATING SITES OF MAIN BUILDINGS OF THERMAL POWER PLANTS

    Directory of Open Access Journals (Sweden)

    Alekseeva Ekaterina Leonidovna

    2012-10-01

    Full Text Available Upon examination of eleven main buildings of power plants, analysis of defects and damages of building structures was performed. Thereafter, the damageability of principal bearing structures of main buildings of thermal plants was analyzed. It was identified that the fastest growing defects and damages were concentrated in the structures of operating sites. The research of the rate of development of the most frequent damages and defects made it possible to conclude that internal corrosion of the reinforcing steel was the most dangerous defect, as far as the reinforced concrete elements of operating sites were concerned. Methods of mathematical statistics were applied to identify the reinforcing steel development pattern inside reinforced concrete elements of floors of operating sites. It was identified that the probability of corrosion of reinforced concrete elements of operating sites was distributed in accordance with the demonstrative law. Based on these data, calculation of strength of reinforced concrete slabs and metal beams was performed in terms of their regular sections, given the natural loads and the realistic condition of structures. As a result, dependence between the bearing capacity reserve ratio and the corrosion development pattern was identified for reinforced concrete slabs and metal beams of operating sites. In order to analyze the sufficiency of the bearing capacity of building structures of operating sites in relation to their time in commission, equations were derived to identify the nature of dependence between the sufficiency of the bearing capacity of reinforced concrete slabs and metal beams of the operating sites and their time in commission.

  3. ULTIMATE LOAD-BEARING CAPACITY OF CYLINDER DERIVED FROM AUTOFRETTAGE UNDER IDEAL CONDITION

    Institute of Scientific and Technical Information of China (English)

    ZHU Ruilin

    2008-01-01

    According to the basic theory on autofrettage and according to the 4th strength theory, several parameters and their relations are studied under ideal condition, including σej/σy, the equivalent stress of total stresses at elastoplastic juncture; σei/σy, the equivalent stress of total stresses at inside surface; σej′/σy, the equivalent stress of residual stresses at elastoplastic juncture; σei′/σy, the equivalent stress of residual stresses at inside surface; and p/σy, load-bearing capaciσy of an autofrettaged σylinder. σy theoretical stuσy on relations between the parameters, noticeable results and laws are achieved: to satisσy |σei′|=σy, the relation between kj and k is, k2lnkj2-k2-kj2+2=0, when k→∞, 1.648 72, as based on the 3rd strength theoσy, where k is the outside/inside radius ratio of a σylinder, kj is the ratio of elastoplastic juncture radius to inside radius of a σylinder; If the plastic region covers the whole wall of a σylinder, for compressiveσyield not to occur after removing autofrettage pressure, the ultimate k is k=2.218 46 as based on the 3rd strength theoσy; With k=2.218 46, a σylinder's ultimate load-bearing capaciσy equals its entireσyield pressure, or p/σy=2lnk/; The maximum and optimum load-bearing capaciσy of an autofrettaged σylinder is just 2 times the loading which an unautofrettaged σylinder can bear elasticalσy, or p/σy=2(k2-1)/k2, and the limit of the load-bearing capaciσy of an autofrettaged σylinder is also just 2 times that of an unautofrettaged σylinder. The conclusions are the same as based on the 3rd strength theoσy, but some equations are different from each other.

  4. Reliability Analysis of Bearing Capacity of Square Footing on Soil with Strength Anisotropy Due to Layered Microstructure

    Directory of Open Access Journals (Sweden)

    Kawa Marek

    2015-12-01

    Full Text Available The paper deals with reliability analysis of square footing on soil with strength anisotropy. The strength of the soil has been described with identified anisotropic strength criterion dedicated to geomaterials with layered microstructure. The analysis assumes dip angle α and azimuth angle β which define direction of lamination of the structure to be random variables with given probability density functions. Bearing capacity being a function of these variables is approximated based on results of deterministic simulations obtained for variety of orientations. The weighted regression method by Kaymaz and McMahon within the framework of Response Surface Method is used for the approximation. As a result of analysis, global factor of safety that corresponds to assumed value of probability of failure is determined. The value of the safety factor denotes the ratio between the value of the design load and the mean value of bearing capacity which is needed to reduce the probability of failure to the acceptable level. The procedure of calculating the factor has been presented for two different cases. In the first case, no information about lamination direction of the soil has been provided and thus all the orientations are assumed to be equally probable (uniform distribution. In the second case, statistical information including mean, variance and assumed probability distribution for both α and β angle is known. For the latter case, using results obtained for few different values of mean of angle α, also the influence of strength anisotropy on the value of global factor of safety is shown.

  5. Influence of cyclic fatigue in water on the load-bearing capacity of dental bridges made of zirconia.

    Science.gov (United States)

    Kohorst, Philipp; Dittmer, Marc Philipp; Borchers, Lothar; Stiesch-Scholz, Meike

    2008-09-01

    The humid atmosphere and permanent occurrence of chewing forces in the oral environment lead to degradation of ceramics used for prosthetic restorations. The aim of this in vitro study was to evaluate the influence of artificial aging on the load-bearing capacity of four-unit bridges, with both undamaged and predamaged zirconia frameworks. Additionally, different parameters for chewing simulation have been investigated and a finite element analysis was made to predict the location of highest tensile stresses within the bridges. A total of 60 frameworks were milled from presintered zirconia and divided into six homogeneous groups. Prior to veneering, frameworks of two groups were "damaged" by a defined saw cut similar to an accidental flaw generated during shape cutting. After veneering, FPDs were subjected to thermal and mechanical cycling - with the exception of control groups. The load-bearing capacity of tested FPDs was significantly reduced by artificial aging. In comparison to unaged specimens, fracture resistance decreased by about 40%, whereas preliminary damage did not have a significant effect. Increasing number of cycles and increasing upper load limit failed to show any additional effect on fracture force. To predict the progression of degradation under the terms of in vitro simulation for even longer periods, further aging experiments are required.

  6. Numerical Analyses of Bearing Capacity of Deep-Embedded Large-Diameter Cylindrical Structure on Soft Ground Against Lateral Loads

    Institute of Scientific and Technical Information of China (English)

    LUAN Mao-tian; FAN Qing-lai

    2006-01-01

    Presented in this paper is a three-dimensional plastic limit analysis method of bearing capacity of the deeply-embedded large-diameter cylindrical structure in the cross-anisotropic soft ground. The most likely failure mechanism is assumed to be of a composite rupture surface which is composed of an individual wedge in the passive zone or two wedges in both active and passive zones near the mudline, depending on the separation or bonding state at the interface between the cylindrical structure and neighboring soils in the active wedge, and a truncated spherical slip surface at the base of the cylinder when the structure tends to overturn around a point located on the symmetry axis of the structure. The cylindrical structure and soil interaction system under consideration is also numerically analyzed by the finite element method by virtue of the general-purpose FEM software ABAQUS, in which the soil is assumed to obey tie Hill's criterion of yield. Both the failure mechanism assumed and the plastic limit analysis predictions are validated by numerical computations based on FEM. For the K0-consolidated ground of clays typically with anisotropic undrained strength property, it is indicated through a parametric study that limit analysis without consideration of anisotropy of soil overestimates the lateral ultimate bearing capacity of a deeply-embedded cylindrical structure in soft ground in a certain condition.

  7. Embedment Effects on the Vertical Bearing Capacity of Offshore Bucket Foundations on Cohesionless Soil

    DEFF Research Database (Denmark)

    Barari, Amin; Ibsen, Lars Bo; Ghalesari, Abbasali Taghavi;

    2017-01-01

    This paper presents the results from a series of physical modeling and three-dimensional finite 9 element (FE) analyses, which examined the uniaxial vertical capacity of suction caissons for 10 offshore wind turbines. The experiments were carried out in quartz sand and involved monotonic 11...... application of vertical load. It was found that the drained capacity of suction caissons is 12 dependent on embedment ratio. On the other hand, predictions from conventional semi-empirical 13 depth factors were found to somewhat underestimate when applied to rough foundations. On the 14 basis of the tests...

  8. Bearing Capacity of Floating Ice Sheets under Short-Term Loads: Over-Sea-Ice Traverse from McMurdo Station to Marble Point

    Science.gov (United States)

    2015-01-01

    ER D C/ CR RE L TR -1 5- 1 Engineering for Polar Operations, Logistics, and Research (EPOLAR) Bearing Capacity of Floating Ice Sheets...Operations, Logistics, and Research (EPOLAR) ERDC/CRREL TR-15-1 January 2015 Bearing Capacity of Floating Ice Sheets under Short-Term Loads Over-Sea-Ice... capacity for a single axle load of 66,000 lb; and the main beams have a minimum yield stress of 36 ksi.* The rounded ends of each girder reduce

  9. Embedment Effects on the Vertical Bearing Capacity of Offshore Bucket Foundations on Cohesionless Soil

    DEFF Research Database (Denmark)

    Barari, Amin; Ibsen, Lars Bo; Ghalesari, Abbasali Taghavi;

    2016-01-01

    This paper presents the results from a series of physical modeling and three-dimensional finite 9 element (FE) analyses, which examined the uniaxial vertical capacity of suction caissons for 10 offshore wind turbines. The experiments were carried out in quartz sand and involved monotonic 11 appli...... and FE analyses, new expressions for depth factor of shallow foundations have 15 been validated for embedment ratios (aspect ratios) up to unity, calibrating the fitting parameters 16 by employing data from a range of soil profiles....... application of vertical load. It was found that the drained capacity of suction caissons is 12 dependent on embedment ratio. On the other hand, predictions from conventional semi-empirical 13 depth factors were found to somewhat underestimate when applied to rough foundations. On the 14 basis of the tests...

  10. Improvement of Bearing Capacity in Recycled Aggregates Suitable for Use as Unbound Road Sub-Base

    Directory of Open Access Journals (Sweden)

    Laura Garach

    2015-12-01

    Full Text Available Recycled concrete aggregates and mixed recycled aggregates are specified as types of aggregates with lower densities, higher water absorption capacities, and lower mechanical strength than natural aggregates. In this paper, the mechanical behaviour and microstructural properties of natural aggregates, recycled concrete aggregates and mixed recycled aggregates were compared. Different specimens of unbound recycled mixtures demonstrated increased resistance properties. The formation of new cement hydrated particles was observed, and pozzolanic reactions were discovered by electronon microscopy in these novel materials. The properties of recycled concrete aggregates and mixed recycled aggregates suggest that these recycled materials can be used in unbound road layers to improve their mechanical behaviour in the long term.

  11. Highly porous organic polymers bearing tertiary amine group and their exceptionally high CO2 uptake capacities

    Science.gov (United States)

    Gomes, Ruth; Bhaumik, Asim

    2015-02-01

    We report a very simple and unique strategy for synthesis of a tertiary amine functionalized high surface area porous organic polymer (POP) PDVTA-1 through the co-polymerization of monomers divinylbenzene (DVB) and triallylamine (TAA) under solvothermal reaction conditions. Two different PDVTA-1 samples have been synthesized by varying the molar ratio of the monomers. The porous polymeric materials have been thoroughly characterized by solid state 13C CP MAS-NMR, FT-IR and UV-vis spectroscopy, N2 sorption, HR TEM and FE SEM to understand its chemical environment, nanostructure, bonding, morphology and related surface properties. PDVTA-1 with higher amine content (DVB/TAA=4.0) showed exceptionally high CO2 uptake capacity of 85.8 wt% (19.5 mmol g-1) at 273 K and 43.69 wt% (9.93 mmol g-1) at 298 K under 3 bar pressure, whereas relatively low amine loaded material (DVB/TAA=7.0) shows uptake capacity of 59.2 wt% (13.45 mmol g-1) at 273 K and 34.36 wt% (7.81 mmol g-1) at 298 K. Highly porous nanostructure together with very high surface area and basicity at the surface due to the presence of abundant basic tertiary amine N-sites in the framework of PDVTA-1 could be responsible for very high CO2 adsorption.

  12. On Bearing Capacity of the Tourism Environment in China%我国旅游环境承载力研究综述

    Institute of Scientific and Technical Information of China (English)

    吴夏楠; 黄倩辉

    2014-01-01

    The development of tourism industry in China shows that the bearing capacity of the tourism environment is a problem for the sustainable development of the tourism industry. The paper systematically reviews the research of theo-retical principles, methods of measurement, practical bearing capacity of the tourism environment in China and the pros-pect of the development trend, which is a summarization of the bearing capacity of tourism environment in China.%文章通过文献法,分别从基础理论、测量方法、实证和发展趋势四个方面,对我国学术界关于旅游环境承载力研究进行了综述。

  13. Least Limiting Water Range and Load Bearing Capacity of Soil under Types of Tractor-Trailers for Mechanical Harvesting of Green Sugarcane

    Directory of Open Access Journals (Sweden)

    Antonio Higino Frederico Pereira

    2015-12-01

    Full Text Available ABSTRACT The expansion of the sugarcane industry in Brazil has intensified the mechanization of agriculture and caused effects on the soil physical quality. The purpose of this study was to evaluate the limiting water range and soil bearing capacity of a Latossolo Vermelho distroférrico típico (Rhodic Hapludox under the influence of different tractor-trailers used in mechanical sugarcane harvesting. The experiment was arranged in a randomized block design with five replications. The treatments consisted of green sugarcane harvesting with: harvester without trailer (T1; harvester with two trailers with a capacity of 10 Mg each (T2; harvester with trailer with a capacity of 20 Mg (T3 and harvester and truck with trailer with a capacity of 20 Mg (10 Mg per compartment (T4. The least limiting water range and soil bearing capacity were evaluated. The transport equipment to remove the harvested sugarcane from the field (trailer at harvest decreased the least limiting water range, reducing the structural soil quality. The truck trailer caused the greatest impact on the soil physical properties studied. The soil load bearing capacity was unaffected by the treatments, since the pressure of the harvester (T1 exceeded the pre-consolidation pressure of the soil.

  14. Interlayer design for the graphite-like carbon film with high load-bearing capacity under sliding-friction condition in water

    Science.gov (United States)

    Wang, Yongxin; Pu, Jibin; Wang, Jiafan; Li, Jinlong; Chen, Jianmin; Xue, Qunji

    2014-08-01

    GLC films with single Ti interlayer, single Cr interlayer, thickness gradient Cr/C interlayer and composition gradient Cr/C interlayer were fabricated by magnetron sputtering technique. The microstructures, mechanical properties and tribological performance under sliding friction in distilled water and seawater of the as-deposited GLC films were investigated. Results showed that the adhesion strength and the load-bearing capacity under sliding-friction condition in water of GLC film could be improved effectively by interlayer design. GLC film with composition gradient Cr/C interlayer exhibited highest adhesion strength and load-bearing capacity under sliding-friction conditions in water, which was closely related to nano-interlocked microstructure and hard carbide phase formations inside the interlayer. The adhesion strength in scratch test and the critical bearing load under sliding-friction in water of the GLC film with composition gradient Cr/C interlayer exceeded 50 N and 2.73 GPa, respectively.

  15. 爆炸荷载下桩基竖向动承载力研究%Study on vertical bearing capacity of pile foundation under blast loading

    Institute of Scientific and Technical Information of China (English)

    王后裕; 姚焕忠; 言志信; 张剑寒; 杨进勇

    2013-01-01

    针对地面抗爆工程建设中桩基设计问题,采用动三轴试验、动力有限元方法等手段,开展了爆炸作用下地基土的动力特性及桩基抗爆承载力研究,结果表明桩基竖向极限抗爆承载力为其竖向极限静承载力2倍以上,高于按照现行桩基规范得到的1.25 ~1.5倍范围值,表明将常规抗震设计的办法直接用于抗爆炸冲击荷载的桩基设计时偏保守.%For the problem of pile foundation design of ground protective projects subjected to blast loading,a series of resrearches of dynamic property of soil and bearing capacity of pile under shock waves are carried out by the methods of dynamic triaxial test and dynamic FEM and so on.The result shows that the dynamic bearing capacity of pile is two times greater than that of static bearing capacity and 1.25 ~ 1.5 times greater than that of current pile code method.Therefore it is conservative to estimate the dynamic bearing capacity of pile with current pile code method.

  16. The influence of framework design on the load-bearing capacity of laboratory-made inlay-retained fibre-reinforced composite fixed dental prostheses

    NARCIS (Netherlands)

    F. Keulemans; L.V.J. Lassilla; S. Garoushi; P.K. Vallittu; C.J. Kleverlaan; A.J. Feilzer

    2009-01-01

    Delamination of the veneering composite is frequently encountered with fibre-reinforced composite (FRC) fixed dental prosthesis (FDPs). The aim of this study is to evaluate the influence of framework design on the load-bearing capacity of laboratory-made three-unit inlay-retained FRC-FDPs. Inlay-ret

  17. Nonlocal axial load-bearing capacity of two neighboring perpendicular single-walled carbon nanotubes accounting for shear deformation

    Science.gov (United States)

    Kiani, Keivan

    2015-11-01

    This study is devoted to examine load-bearing capacity of a nanosystem composed of two adjacent perpendicular single-walled carbon nanotubes (SWCNTs) which are embedded in an elastic matrix. Accounting for the nonlocality and the intertube van der Waals forces, the governing equations are established based on the nonlocal Euler-Bernoulli, Timoshenko, and higher-order beam theories. These are sets of coupled integro-ordinary differential equations whose analytical solutions are unavailable. Hence, an efficient meshless methodology is proposed and the discrete governing equations are obtained via Galerkin approach. By solving the resulting set of eigenvalue equations, the axial buckling load of the elastically embedded nanosystem is evaluated. The roles of the radius and slenderness ratio of the constitutive SWCNTs, free distance between two tubes, small-scale parameter, aspect ratio, transverse and rotational stiffness of the surrounding matrix on the axial buckling load of the nanosystem are comprehensively addressed. The obtained results can be regarded as a pivotal step for better understanding the mechanism of elastic buckling of more complex systems such as elastically embedded-orthogonal membranes or even forests of SWCNTs.

  18. Comparison of Effects of Using Geosynthetics and Lime Stabilization to Increase Bearing Capacity of Unpaved Road Subgrade

    Directory of Open Access Journals (Sweden)

    Erhan Burak Pancar

    2016-01-01

    Full Text Available So many soil improvement methods have been developed in order to increase bearing capacity of superstructure of the road to be constructed on the soft clayey road base soils, decrease settlements, and increase other strength specifications (CBR, k, MR values, etc.. In this paper, lime stabilization of clayey road base soil with high water content and its improvement with geosynthetics (geocell + geotextile reinforcement and comparisons of these two different improvement methods were made. For this purpose, plate loading experimental comparisons of clayey soil, which had high water content by 10% increasing the optimum water content, were made after it was improved with lime at the rates of 3, 6, and 12%, geotextile reinforcement, geocell reinforcement, geosynthetics reinforcement, and geosynthetics reinforcement + lime stabilization at various rates. It was understood that these improvement methods will not yield sufficient results on clayey soils with high water content on their own, and method of improvement with lime and then reinforcement with geosynthetics yields better results on these types of soils. Only one improvement state among ten different states examined in this study gave the sufficient results for the soil to be used for unpaved roads.

  19. Load-bearing capacity of all-ceramic posterior four-unit fixed partial dentures with different zirconia frameworks.

    Science.gov (United States)

    Kohorst, Philipp; Herzog, Timo J; Borchers, Lothar; Stiesch-Scholz, Meike

    2007-04-01

    The aim of this in vitro study was to compare the load-bearing capacity of posterior four-unit fixed partial dentures (FPDs) produced with two different yttria-stabilized polycrystalline tetragonal zirconia (Y-TZP) ceramics, one being a presintered material, the other a fully sintered, hot isostatically pressed material. Additionally, as a novel approach, the influence of preliminary mechanical damage upon the fracture force of an FPD has been investigated. A total of 20 frameworks each were milled from presintered zirconia and from fully sintered zirconia. Prior to veneering, 10 frameworks of each material were 'damaged' by a defined saw cut similar to an accidental flaw generated during shape cutting. Before fracture testing, all FPDs were subjected to thermal and mechanical cycling. Additionally, scanning electron microscopy was used to investigate fracture surfaces. Statistical analysis showed that FPDs milled from fully sintered zirconia had a significantly higher fracture resistance compared with specimens made from presintered material, whereas preliminary damage did not have a significant effect. After aging, FPDs made from both materials were capable of withstanding occlusal forces reported in the literature. Therefore, both types of Y-TZP may be suitable for posterior four-unit all-ceramic FPDs, although further prolonged aging experiments and prospective clinical trials are required to prove their fitness for clinical use.

  20. The Effect of Indenter Ball Radius on the Static Load Capacity of the Superelastic 60NiTi for Rolling Element Bearings

    Science.gov (United States)

    DellaCorte, Christopher; Moore, Lewis E., III; Clifton, Joshua S.

    2014-01-01

    Static load capacity is a critical design parameter for rolling element bearings used in space mechanisms because of the potential for Brinell (surface dent) damage due to shock and vibration loading events during rocket launch. Brinell damage to bearing raceways can lead to torque variations (noise) and reduced bearing life. The growing use of ceramic rolling elements with high stiffness in hybrid bearings exacerbates the situation. A new family of hard yet resilient materials based upon nickel-titanium is emerging to address such bearing challenges. 60NiTi is a superelastic material that simultaneously exhibits high hardness and a relatively low elastic modulus (approx. 100 GigaPascals) and has been shown to endure higher indentation loads than conventional and high performance steel. Indentation load capacity has been reported for relatively large (12.7 millimeters diameter) ceramic (Si3N4) indenter balls pressed against flat plates of 60NiTi. In order to develop damage load threshold criteria applicable to a wide range of bearing designs and sizes, the effects of indenter ball radius and the accuracy of interpolation of the Hertz contact stress relations for 60NiTi must be ascertained. In this paper, results of indentation tests involving ceramic balls ranging from 6.4 to 12.7 mm in diameter and highly polished 60NiTi flat plates are presented. When the resulting dent depth data for all the indenter ball sizes are normalized using the Hertz equations, the data (dent depth versus stress) are comparable. Thus when designing bearings made from 60NiTi, the Hertz stress relations can be applied with relative confidence over a range of rolling element sizes and internal geometries.

  1. Experimental and prediction study for bearing capacity of inflatable wing%柔性机翼承载能力的试验与预测

    Institute of Scientific and Technical Information of China (English)

    王志飞; 王华; 王伟; 贾青萍

    2012-01-01

    Experimental and prediction study for bearing capacity of inflatable wing have been done and described in this paper. Firstly, model of aerofoil was established, structure of inflatable wing was analyzed and optimized, then method of orthogonal experiment was used to ascertain the main impact of influence bearing capacity and experimental of inflatable wing was finished for bearing capacity. Artificial neural network was finally adopted to pre- dict bearing capacity. The results show that: (1) In the initial experiment, at the same pressure, the relationship between loading and deflection approximately abides by linearity relations. When reached the fixed pressure, the relationship between loading and deflection is also linearity, but the slope abruptly increases. (2) The relative error between the pre- dicted result and the experiment result is 12G, and standard deviation 0.39%, and show that the bearing capacity prediction model of neural net work can predict the bearing capacity of inflatable wing accurately and rapidly.%对柔性机翼进行了承载能力的试验及预测研究,首先对柔性机翼的翼型结构进行建模,并对充气机翼的结构进行了分析和优化;其次应用正交试法确定出影响柔性机翼承载能力的主要影响因素,以优化后的结果建立实物模型和主要影响因素为变量进行试验;最后以大量的试验数据为训练样本建立改进的神经网络模型,并进行承载能力预测.试验与预测结果对比研究表明:在初始阶段,柔性机翼在压强一定时,载荷与挠度近似呈线性关系;在同一气压值下,载荷增加到一定值时,载荷与挠度的关系曲线呈近似线性关系,而是斜率突然减小;神经网络测试值和试验实测值最大相对误差与标准方差只有12%和0.39%,人工神经网络解析方法可以用于对充气机翼抗弯刚度的分析.

  2. The Test and Study of RPC Capping Plate Bearing Capacity and Crack Resistance%RPC盖板承载力与抗裂性试验研究

    Institute of Scientific and Technical Information of China (English)

    黄旭毅; 吴伟

    2013-01-01

      以京沪高速铁路三标段曲阜 RPC 混凝土盖板厂为依托,介绍 WDW -10型微机监测高强道板抗弯承载力试验机的开发和设计情况,并对 RPC 盖板承载力与抗裂性进行试验研究。%  The paper briefs the development and the design of the type WDW – 10 microcomputer - moni-tored high strength side walk slab bending resistant bearing capacity tester by relying on Qufu RPC Cap -ping Plate Precast Factory for the Bid 3 section of the Beijing - Shanghai High Speed Railway .Both test and study of RPC capping plate bearing capacity and crack resistance have been performed .

  3. Load-bearing capacity of screw-retained CAD/CAM-produced titanium implant frameworks (I-Bridge®2 before and after cyclic mechanical loading

    Directory of Open Access Journals (Sweden)

    Marc Philipp Dittmer

    2013-07-01

    Full Text Available Implant-supported screw-retained fixed dental prostheses (FDPs produced by CAD/ CAM have been introduced in recent years for the rehabilitation of partial or total endentulous jaws. However, there is a lack of data about the long-term mechanical characteristics. OBJECTIVE: The aim of this study was to investigate the failure mode and the influence of extended cyclic mechanical loading on the load-bearing capacity of these frameworks. MATERIAL AND METHODS: Ten five-unit FDP frameworks simulating a free-end situation in the mandibular jaw were manufactured according to the I-Bridge®2-concept (I-Bridge®2, Biomain AB, Helsingborg, Sweden and each was screw-retained on three differently angulated Astra Tech implants (30º buccal angulation/0º angulation/30º lingual angulation. One half of the specimens was tested for static load-bearing capacity without any further treatment (control, whereas the other half underwent five million cycles of mechanical loading with 100 N as the upper load limit (test. All specimens were loaded until failure in a universal testing machine with an occlusal force applied at the pontics. Load-displacement curves were recorded and the failure mode was macro- and microscopically analyzed. The statistical analysis was performed using a t-test (p=0.05. RESULTS: All the specimens survived cyclic mechanical loading and no obvious failure could be observed. Due to the cyclic mechanical loading, the load-bearing capacity decreased from 8,496 N±196 N (control to 7,592 N±901 N (test. The cyclic mechanical loading did not significantly influence the load-bearing capacity (p=0.060. The failure mode was almost identical in all specimens: large deformations of the framework at the implant connection area were obvious. CONCLUSION: The load-bearing capacity of the I-Bridge®2 frameworks is much higher than the clinically relevant occlusal forces, even with considerably angulated implants. However, the performance under functional

  4. Vertical variation of trace elements and its relation to the water-bearing capacity of Ordovician strata,in Datun coal field

    Institute of Scientific and Technical Information of China (English)

    LIU Huai-zhong; HAN Bao-ping

    2009-01-01

    We tested for fourteen trace elements in samples collected from the Ordovician strata in Datun coal field. The vertical concentration variation of these trace elements is reported. The relationship of the variation to the water-beating capacity of the Ordovician strata is discussed. The minimum concentration of eleven (of 14 total) trace elements appears in the lower Majiagou formation. The maximum concentrations mainly appear in the Badou and Jiawang formations: eight maxima are located in Badou and four more are in Jiawang. The study of karst development and the water-bearing capacity of Ordovician strata shows that karst is well developed in the Majiagou formation and there is a consequent high water-beating capacity in this formation: Badou and Jiawang formations are contrary to this situation. The results illustrate that the minimum concentrations of most trace elements within certain Ordovician formations can be taken as strong evidence for the existence of a well developed karst and a high wa-ter-bearing capacity.

  5. PHC管桩受弯承载力的分析%ANALYSIS ON THE FLEXURAL BEARING CAPACITY OF PHC PIPE PILE

    Institute of Scientific and Technical Information of China (English)

    高安; 张亮

    2013-01-01

    利用ABAQUS有限元软件,建立4个PHC管桩有限元模型,分析桩型(AB型和A型)、箍筋间距和箍筋直径对PHC管桩受弯承载力的影响.比较了公式和有限元计算得出的极限弯矩之间的差异.分析结果表明,AB型管桩的受弯承载力大于A型管桩的受弯承载力,减小箍筋间距和增大箍筋直径不能提高PHC管桩的极限弯矩,有限元分析得到的结果大于公式计算的结果.%Through the finite element software of ABAQUS,the impact of the pile type and stirrup on PHC pipe pile' s flexural bearing capacity is analyzed. The difference of the ultimate bending moment between the formula and finite element is compared. The results show that: the flexural bearing capacity of AB - type is greater than that of A - type. Decreasing stirrup spacing and increasing stirrup diameter can t improve the ultimate bending moment of PHC pipe pile. The result of finite element is bigger than the result of the formula.

  6. Relationship between pile foundation bearing capacity and its dynamic stiffness%桩基承载力与其动刚度的关系

    Institute of Scientific and Technical Information of China (English)

    刘建磊; 马蒙; 张勇; 缴玉森

    2015-01-01

    为分析桩基承载力与机械阻抗法中动刚度的关系,在同一场地设计了4根相同尺寸的带有不同程度缺陷的模型桩(缩颈桩或断桩),对模型桩进行了机械阻抗法动测和静载试验。建立了桩—土有限元模型,利用模型桩测试数据对有限元模型进行校准,并分析了完整桩在冲击动荷载和静载试验中对主要物理参数的敏感性;同时分析了缩颈、扩颈缺陷对桩基动刚度的影响规律。研究结果表明:对于相同形式、相近地层环境中的桩基,动刚度能很好地反映静力特性;动刚度对影响桩基承载能力的缺陷较为敏感,合理动刚度下限值可以作为桩基承载力的预警值。%In order to investigate the relationship between the bearing capacity of pile foundation and its dynamic stiffness in the impulse transient response method ( T RM ) ,four model piles,with same size but different damage ( necking or breaking) ,were designed in a same test field. Dynamic response was measured with T RM and static load test was performed. A pile-soil finite element model was built,calibrated by model pile tests. Sensitivity of main parameters were analyzed for intact piles under impulse and static loads,and the effect of necking or expanding defects on dynamic stiffness were studied. It revealed that dynamic stiffness reflected the corresponding static characteristics for pile foundations with the same type and located in similar ground environment. Dynamic stiffness is sensitive to the defects which affect the pile bearing capacity,and a reasonable lower bound of dynamic stiffness can be used as a precaution for pile bearing capacity.

  7. Foil bearings

    Science.gov (United States)

    Elrod, David A.

    1993-11-01

    The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are: (1) rolling or sliding contact within the bearing has life-limiting consequences; and (2) REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contracts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exists for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. This report describes the first phase of a structural analysis of a bending-dominated, multileaf CFB. A brief discussion of CFB literature is followed by a description and results of the present analysis.

  8. Foil bearings

    Science.gov (United States)

    Elrod, David A.

    1993-01-01

    The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are: (1) rolling or sliding contact within the bearing has life-limiting consequences; and (2) REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contracts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exists for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. This report describes the first phase of a structural analysis of a bending-dominated, multileaf CFB. A brief discussion of CFB literature is followed by a description and results of the present analysis.

  9. 桩基承载能力的有限元分析%Finite Element Analysis of Bearing Capacity of Pile Foundation

    Institute of Scientific and Technical Information of China (English)

    彭银辉; 吕世斌; 耿立伟

    2012-01-01

    针对工程实例,利用ABAQUS有限元软件建立单桩承载力的有限元计算模型,研究桩基承载特性,并与桩基静载试验所得实测数据比较。结果表明,模拟计算结果与工程实际基本吻合,说明采用的计算方法和模型是合理可行的。同时研究了在不同桩土界面摩擦系数条件下桩的沉降和轴向力变化情况,为不同工程地质条件的桩基设计提供参考。%On account of practical case,finite element calculation model of single pile bearing capacity is established with ABAQUS to study the bearing characteristics of pile foundation and compare with actual measurement data of static loading test of pile foundation.The result shows that simulated calculation result is basically consistent with actual engineering,which indicates that the adopted calculation method and model are reasonable and feasible.Meanwhile,the change of settlement and axial force of pile under different frictional coefficient of pile soil is studied,providing references for pile foundation design in different engineering geological conditions.

  10. Vulnerability Assessment on Government's Marine Disaster Bearing Capacity%海洋灾害中政府承灾力脆弱性研究

    Institute of Scientific and Technical Information of China (English)

    赵昕; 王晓婷

    2011-01-01

    The information diffusion method can turn a distinct value of the sample point into a fuzzy set, and turn a single point into set-valued sample point. This method is especially applicable to the situation in which marine disaster is non-continuous and sample points are fewer in number. It can dig out the maximum information carried by the data themselves. This paper's study subject is the municipal area. First, an evaluation model of the vulnerability of government's disaster bearing capacity is setup based on the information diffusion principle. And the exceeding probability of a government's disaster bearing coefficient is brought in to evaluate it. Next, the vulnerability made through the hierarchical clustering method is given, taking Shandong province as an erample for an empirical research. Then, the vulnerability of government's marine bearing capacity of the coastal cities in Shandong Province is classified. At the end, a risk map is drawn. The research results show that the vulnerability of government's disaster bearing capacity is the heaviest in the cities of Weihai, Yantai, Dongying and Rizhao; Qingdao and Binzhou are the second; Weifang is the city with the minimum vulnerability of government's disaster bearing capacity. The causes for the difference of vulnerability vary from city to city, mainly in the disaster occur rence probability of each city, the level of economic development, and attention to the disaster. In the long run, the improvement of government's marine disaster bearing capacity depends on minimizing the economic loss of marine disasters and maximum funds preparation to cope with the disaster. All of these can give some reference to the concerned departments at all levels when policies are formulated to improve disaster resistance and reduction capacity.%信息扩散方法可以将一个分明值的样本点变成一个模糊集,把单值点变成集值样本点.这种方法对于海洋灾害呈现的非连续、样本点个数少的

  11. Highly porous organic polymers bearing tertiary amine group and their exceptionally high CO{sub 2} uptake capacities

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Ruth; Bhaumik, Asim, E-mail: msab@iacs.res.in

    2015-02-15

    We report a very simple and unique strategy for synthesis of a tertiary amine functionalized high surface area porous organic polymer (POP) PDVTA-1 through the co-polymerization of monomers divinylbenzene (DVB) and triallylamine (TAA) under solvothermal reaction conditions. Two different PDVTA-1 samples have been synthesized by varying the molar ratio of the monomers. The porous polymeric materials have been thoroughly characterized by solid state {sup 13}C CP MAS-NMR, FT-IR and UV–vis spectroscopy, N{sub 2} sorption, HR TEM and FE SEM to understand its chemical environment, nanostructure, bonding, morphology and related surface properties. PDVTA-1 with higher amine content (DVB/TAA=4.0) showed exceptionally high CO{sub 2} uptake capacity of 85.8 wt% (19.5 mmol g{sup −1}) at 273 K and 43.69 wt% (9.93 mmol g{sup −1}) at 298 K under 3 bar pressure, whereas relatively low amine loaded material (DVB/TAA=7.0) shows uptake capacity of 59.2 wt% (13.45 mmol g{sup −1}) at 273 K and 34.36 wt% (7.81 mmol g{sup −1}) at 298 K. Highly porous nanostructure together with very high surface area and basicity at the surface due to the presence of abundant basic tertiary amine N-sites in the framework of PDVTA-1 could be responsible for very high CO{sub 2} adsorption. - Graphical abstract: Exceptionally high CO2 uptake (85.8 wt % at 273 K) has been observed over a high surface area porous organic polymer PDVTA-1 synthesized through copolymerization of divinylbenzene and triallyl amine. - Highlights: • Designing the synthesis of a new N-rich cross-linked porous organic polymer PDVTA-1. • PDVTA-1 showed mesoporosity with very high surface area of 903 m{sup 2} g{sup −1}. • High surface area and presence of basic sites facilitates the CO{sub 2} uptake. • PDVTA-1 showed exceptionally high CO{sub 2} adsorption capacity of 85.8 wt% at 273 K, 3 bar pressure.

  12. Experimental Methods of Load Bearing Capacity Under High Temperature in Aerospace Composite Materials%航天用复合材料结构高温极限承载能力试验方法

    Institute of Scientific and Technical Information of China (English)

    卢睿; 范新中; 王世勋; 王婧超

    2012-01-01

    Countering the flight character of astronautical flight vehicle, two experimental methods of load bearing capacity were summarized, in order to obtain the structural load bearing capacity under different flight temperature and different flight duration. It was able to express the high temperature load bearing capacity of the material in the process of heat transfer, reducing the weight of structural heat resistance.%针对航天飞行器飞行特点,本文给出两种基于破坏时间的承载能力试验方法,可以获得结构在不同飞行温度和时间下的承载能力.能够充分发挥材料在传热过程中的高温承载能力,降低结构防热质量.

  13. Application of Excel in Estimating the Vertical Bearing Capacity of Pile Foundation%Excel在桩基竖向承载力估算中的应用

    Institute of Scientific and Technical Information of China (English)

    尤苏南

    2013-01-01

    Use Excel's strong functions of data looking for, data calculation and data processing, carry out the estimation of vertical bearing capacity of single-pile comply with the common formula, large diameter pile formula, socket-pile formula, anti-pull up pile formula, later inject mortar formula etc. only need to set up its function, formula and simple macro order, enter the stratum data and the parameter of pile foundation calculation. Specially fit for the pile foundation scheme selection for the large and complicated project with different location, different device, different pile type, different pile diameter and different pile end bearing layer, largely enhance the work efficiency.%  利用Excel强大的数据查找、计算、处理功能,只需进行Excel的函数、公式、简单宏命令设置,输入地层数据和桩基计算参数,就能按桩基的通用公式、大直径桩公式、嵌岩桩公式、抗拔桩公式、后注浆公式等,进行单桩竖向承载力估算。尤其适用于大型或复杂工程中不同工点、不同装置、不同桩型、不同桩径、不同桩端持力层等多种条件下的桩基方案比选,可以大大提高工作效率。

  14. 地下水位上涨对地基土承载力的影响分析%Analysis of the influence on bearing capacity of foundation by water table rise

    Institute of Scientific and Technical Information of China (English)

    陆亚兵; 李春博

    2014-01-01

    从地基土承载力的计算公式出发,对比分析了不同基础宽度、不同基础埋深、不同土性的地基土承载力受水位变化的影响,分析显示:地下水位在基础底板以下变化时,对地基土的承载力影响较小,地下水位上涨至基础底板以上时,承载力明显下降。%The goal of this paper is to comparative analysis the influence of the bearing capacity of the foundation soil by the change of water level in different width of foundation,depth of the subbasement and quality of the foundation soil which is based on the bearing capacity equation in code,the analyzation shows that there is little effect to the bearing capacity when water level changes under the baseplate,nevertheless,when the head of groundwater raise upon the baseboard,bearing capacity will decline significantly.

  15. 复合桩基地基极限承载力的下限有限元解%Finite element lower bound limit solutions for ultimate bearing capacity of subsoil under raft of composite piled foundations

    Institute of Scientific and Technical Information of China (English)

    蒋刚; 孙君; 王旭东

    2011-01-01

    When the composite piled foundation reaches the general ultimate bearing capacity status, an increment of the ultimate bearing capacity for natural foundation is induced by "barrier effect" of piles.The analysis of the problem can be simplified for both the sum of the vertical ultimate bearing capacity of foundation and the increment of the ultimate bearing capacity of foundation soil horizontally sliding around piles.Based on the finite element plastic lower bound limit method, the numerical solutions for the vertical ultimate bearing capacity of foundation and the horizontal resistance sliding around piles varying with soil depth are obtained, and the sliding resistance formula is also established.The sliding resistance coefficient &s reduces with the increase of pile spacing.The increment of the ultimate bearing capacity △fu decreases with the increase of pile spacing.The results indicate that the resistance sliding around piles in the composite piled foundation is being and can not be ignored, and that the ultimate bearing capacity of the composite piled foundation has certain increment, which can be regarded as the security reserve of foundation.%复合桩基在达到整体极限承载状态时,因桩的"遮拦作用"使得地基极限承载力较天然地基有一定提高.其分析可简化为地基竖向极限承载力和地基土水平向绕桩作用产生的极限承载力提高值的叠加.利用下限有限元方法,求解得到地基的极限承载力和不同深度处土体绕桩阻力的数值解,并建立了绕桩阻力计算公式.绕桩阻力系数ks随桩间距的增加而逐渐减小.地基极限承载力提高值△fu随桩间距的增加而逐渐降低.计算表明:复合桩基下绕桩阻力存在并不可忽视,承台下地基极限承载力有明确的提高,可以作为地基的安全储备.

  16. Water resource bearing capacity study for Xijiang River economic belt in Guangxi%广西西江经济带水资源承载力研究

    Institute of Scientific and Technical Information of China (English)

    孙夏平

    2014-01-01

    分析西江经济带现状供用水情况,计算西江经济带可利用水资源潜力并进行评价;按照实行最严格水资源管理制度要求,分析西江经济带水资源承载力,并提出合理调整经济布局、加快产业结构调整、转变用水方式,以及加强水资源管理等建议。%For the Xijiang River economic belt in Guangxi,the author analyzed the current status of water supply and demands;calculated and appraised the potential of water resources;predicted the bearing capacity of water re-sources in accordance with requirements of the most strict water resources administration system;and proposed to properly adjust the economic layout,accelerate adjustment of industrial structure,change water use mode,and strengthen administration of water resources.

  17. Shear Bearing Capacity of Ultra-High Performance Concrete Shear Wall%超高性能混凝土剪力墙抗剪承载力分析

    Institute of Scientific and Technical Information of China (English)

    钟益东; 童小龙; 甘文举

    2015-01-01

    This paper uses nonlinear finite element analysis upon the basic behavior of Ultra -high performance concrete shear wall subjected to monodirectional lateral load, and studies the effect of axial load ratio, shear span ratio, the ratio of hidden column longitudinal, the volumetric ratio of hidden column and the ratio of web reinforcement on the shear bearing capacity. The research shows that: the bearing capacity of UHPC shear wall is high; the displacement ductility of UHPC shear wall is well. With the increased of axial load ratio, the bearing capacity is first increased and then decreased, the ductility drop significantly, so axial load ratio should be strictly controlled; With the shear span ratio increased, the destruction of morphological change and the bearing capacity increase; With the ratio of hidden column longitudinal increasing, the bearing capacity increase; the volumetric ratio of hidden column, the ratio of web horizontal reinforcement and the ratio of web vertical reinforcement effect on bearing capacity are not very obvious.%对超高性能混凝土UHPC(Ultra-High Performance Concrete)剪力墙在单向水平荷载作用下的受力过程进行了非线性有限元分析。重点分析了轴压比、剪跨比、暗柱纵筋配筋率、暗柱箍筋配箍率、分布钢筋配筋率等因素对UHPC剪力墙抗剪承载力的影响。结果表明: UHPC混凝土剪力墙抗剪承载力高,延性较好,值得在工程领域应用。随着轴压比的增大,承载力先增大后减小,延性大幅下降,应该严格控制轴压比;随着剪跨比增大,破坏形态发生变化,承载力减小;随着暗柱纵筋配筋率的增大,承载力增大;暗柱箍筋体积配箍率及分布钢筋的增大对承载力的影响不很明显。

  18. Discussion on Calculation of Vertical Bearing Capacity of Rock-socketed Pile%嵌岩桩竖向承载力计算问题探讨

    Institute of Scientific and Technical Information of China (English)

    吕世明; 范开敏

    2014-01-01

    The formulas for bearing capacity of the rock-socketed pile in current industry standards are different from each other.The cause of the difference is pointed out based on analyzing the existing data comprehensively, and also some of the other problems.The results of comparative analysis show that the standard empirical formu-lae have the advantages as easy calculating and convenient spreading,which are calculated by the use of uniaxial compressive strength,but there is limitation of weak control for the influencing factors,and the calculated results tend to be conservative.Although theoretical analytic solutions are usually more closer to the in-site measured values than empirical values,it is not suitable for engineering works because of the multitudinous variables and complex calculation;so it is recommended that the design and application of the rock-socketed pile should focus on the accumulation of experiences and the establishment of regional standards.Furthermore,a method is pro-posed to determine the optimal embedding depth,and it is corresponding to the depth when the lateral resistance or end resistance accounting for the total load of the embedded section about 40% to 60%,by the way,the cal-culation of the bearing capacity of the pile at this depth is achieved by the introduction of partial coefficients.%在综合分析现有文献的基础上,指出现行各行业规范中嵌岩桩承载力计算公式产生差异的缘由及存在的问题。通过对比分析指出,规范经验公式采用岩石单轴抗压强度计算嵌岩桩承载力具有计算简单、便于推广应用的优点,但也存在对影响因素控制性差的局限,计算结果往往偏保守;理论计算通常较规范经验值更接近于现场实测值,但其参数繁多、计算复杂而不便于应用。建议嵌岩桩设计应在现行国家标准规范的基础上,注重地区经验的积累并建立健全地方标准。通过对嵌岩深度问题的深入分析

  19. Study on bearing capacity of concrete gravity dam%混凝土重力坝承载能力的分析研究

    Institute of Scientific and Technical Information of China (English)

    孙恭尧; 钱之光; 殷有泉

    2001-01-01

    混凝土重力坝的承载能力是高坝设计中重要的研究课题.本文根据应变空间表述的弹塑性增量理论,采用稳定性分析方法研究重力坝的承载能力,给出混凝土重力坝与坝基岩石系统失稳的判别准则,同时按两种不同的材料强度储备方式,研究重力坝的承载能力.这种方法能反映因混凝土和岩石材料损伤和软化导致重力坝系统失稳的物理机制,使分析建立在一个严谨的力学基础之上.计算实例表明,本方法可作为一个合理和可行的分析方法.%Based on the elastic-plastic increment theory the bearing capacity of concrete gravity dam is studied using stability and analytic method expressed in strain space. Criterion for stability of concrete gravity dam and foundation rock system is proposed. Two kinds of material strength margin are considered in the study. This analytical method is able to reflect the physical mechanism of concrete gravity dam system if unstable state is occurred due to damage or softening of concrete and rock. The calculation result indicates that the method is rational and feasible.

  20. Calculation of axially bearing capacity of a batter pile based on mechanism of deformation compatibility%基于变形协调的斜桩轴向承载力计算方法

    Institute of Scientific and Technical Information of China (English)

    张麒蛰; 卓卫东; 范立础

    2013-01-01

    In order to obtain the axial bearing capacity of a batter pile , the calculation formula for the axially bearing capacity of a batter pile was deduced based on the non-uniform distribution char-acteristics of the friction resistance around the batter pile shaft and the mechanism of pile -soil deformation compatibility .The results calculated by the proposed formula and the method given by the design code of pile were compared to explore the influence of the factors , such as pile inclina-tion, diameter, length and utmost friction resistance around pile shaft , on axial bearing capacity. The calculated results showed that the value of the pile axially bearing capacity calculated by the proposed formula decreased with the increase of pile inclination .For different pile diameters , the pile axially bearing capacity was 7%smaller than that calculated by the code's formula.The shorter of the pile length or the lesser of the utmost friction resistance of the pile was , the smaller bearing capacity calculated by the code's formula was than the values calculated by the proposed formula . Finally , with the increase of the pile length or utmost friction resistance , the value of bearing capaci-ty calculated by this proposed formula was greater than the value calculated by the code's formula. The proposed formula also takes into account of the influence of pile inclination and the mechanism of pile-soil deformation compatibility .It can be a reference to calculate axial bearing capacity of bat-ter piles.%为进一步研究斜桩轴向承载力计算方法,基于斜桩的桩周摩阻力不均匀分布的特性和桩-土受力变形协调的原则,推导了斜桩轴向承载力计算公式,通过对比本文公式与规范公式的计算结果,揭示了桩身倾角、桩径、桩长和桩侧极限摩阻力等因素对斜桩轴向容许承载力的影响规律。结果表明:鉴于规范公式未考虑斜桩桩身倾角对承载力的影响,本文公式计算得

  1. 矿柱下软弱夹层的极限承载力分析%Analysis of Ultimate Bearing Capacity of Soft Interlayer under Pillar

    Institute of Scientific and Technical Information of China (English)

    殷勇; 乔来军; 周国庆

    2015-01-01

    软弱夹层是一种广泛存在的地质构造,地下采矿工程中软弱夹层的存在往往给矿柱的设计及稳定性分析带来不利。针对软弱夹层的极限承载力,采用Prandtl塑性挤出破坏模式和极限分析上限法,同时考虑夹层面不同位置的剪应力条件,求得了平面应变条件及空间轴对称条件下软弱夹层极限压力的计算式。对计算数据的分析表明,软弱夹层的极限压力与夹层的宽高比及夹层面的摩擦系数之间具有一定的规律。总体而言,软弱夹层的极限压力随夹层的宽高比及夹层面摩擦系数的增加而增大,同时夹层面的摩擦条件对极限压力的影响也随宽高比的增加而更加显著,但摩擦系数增加至一定程度时其对各种宽高比尺度下极限压力的影响逐步减弱直至消失。此外,与夹层面采用单一摩擦条件的其他方法相比,夹层宽高比较小时所得到的解答与其他方法解答相差不大,夹层宽高比较大时解答结果高于其他方法,但在摩擦系数或粗糙程度极高的情况下几种方法的解答近似相等。推导得出的极限承载力计算式可以为下伏软弱夹层的矿柱设计及稳定性分析提供参考。%Soft interlayer in rock and soil mass is a widespread geological structure. In underground mining engineering, the existence of soft interlayer will bring disadvantages to the design and stability analysis of pillar. In view of the ultimate bear-ing capacity of soft interlayer,based on Prandtl's plastic extrusion failure mode and upper bound limit analysis method,formu-lae of ultimate pressure of soft interlayer are deduced under plane strain condition and space axisymmetric condition,where dif-ferent shearing stress conditions of various locations on the surface of soft layer are also taken into account. Analysis of calculat-ed data shows that,the ultimate pressure of soft interlayer has a relationship with width

  2. 热模锻传动轴滑动轴承承载力分析%Analysis on the Load Capacity of Slip Bearing for Cardan Shaft of Hot Die Forging Press

    Institute of Scientific and Technical Information of China (English)

    魏田华; 殷文齐; 杜建伟

    2015-01-01

    The essay introduces the Reynolds equation used to calculate the load capacity of oil film of slip bearing which is in dynamic pressure and radial type for the cardan shaft of the hot die forging press. The key dimension of the bearing is designed by Reynolds model. The finite element model is created based upon such dynamic pressure and radial slip bearing, the result of which analyse the pressure distribution on the oil film and variation of load capacity under different minimum oil film thickness. It concludes the maximum load capacity and the corresponding different minimum oil film thickness.%介绍用于动压径向滑动轴承油膜承载能力计算的雷诺方程。根据雷诺计算模型确定某热模锻压机传动轴滑动轴承的关键尺寸,并以该动压径向滑动轴承为基础,建立有限元模型,分析在不同最小油膜厚度下油膜上的压力分布和承载力变化,分析得出滑动轴承的最大承载能力及其所对应的最小油膜厚度。

  3. Study about Ultimate Bearing Capacity of Large Steel Box Girder under the Action of Shear Force%剪力作用下大型钢箱梁极限承载力研究

    Institute of Scientific and Technical Information of China (English)

    王龙奉; 吕彭民; 徐田

    2015-01-01

    The rules about the ultimate bearing capacity of the welded box girder in the current GB5001 7-2003 “Structural Design Specification”are faulty.The influences of the material non-linearity, geometrical non-linearity and the initial defect are considered in this paper.The arc length increment method obtained by revising Newton-Raphson formula is used to solve the ultimate bearing capacity of welded box girder under the action of the shear force,and the correctness of the calculation method is validated through the model tests.The formula used to calculate the stable ultimate bearing capacity under the action of the shear force of the box girder is summarized through large of simulation calculations.The method relates di-rectly the ultimate bearing capacity to the height to thickness ratio of the web and width to thickness ratio of the wing plate,which has the reference value to calculate and design the stable ultimate bearing capacity of the welded box girder.%现行 GB50017-2003《钢结构设计规范》对焊接箱形截面梁极限承载力规定还比较粗糙,本文考虑材料非线性、几何非线性和箱梁初始缺陷的影响,采用对 Nweton-Raphson 公式进行修正的弧长增量法求解剪力作用下焊接箱梁极限承载力,并通过模型试验,验证了计算方法的正确性。通过大量的数值模拟仿真计算,归纳总结出了箱形截面梁在剪力作用下稳定极限承载力计算公式。该公式把极限承载力与腹板高厚比、翼板宽厚比直接关联起来,对焊接箱形截面梁稳定极限承载力的计算及设计具有参考价值。

  4. 多种加固方法应用于双曲拱桥主拱圈的提载加固%Reinforcement for Improving Bearing Capacity of A Double Arch Bridge Main Arch by Strengthen Methods

    Institute of Scientific and Technical Information of China (English)

    黄伟; 申波; 薛守宝; 梁影

    2012-01-01

    In this paper, reinforcement for improving the bearing capacity of a double arch bridge is studied. Based on the test results of a double-arched bridge of Anshun in Guizhou province, the strengthening program of the main arch is proposed. At the section of arch feet, the moment bearing capacity is improved by enlarged upper edge concrete and lower edge concrete of the section, the section is changed to box section. At the other section of the arch, the negative moment bearing capacity is improved by enlarged upper edge concrete of the section, and the positive moment bearing capacity is improved. For the deficiencies of the positive moment bearing capacity, the bonding steel plate is recommended at the arch rib of the other section. The results show that the reinforcement methods can improve load level of the bridge effectively. The construction of the bridge is convenient and can satisfy the design goals.%针对双曲拱桥的提载加固,基于贵州省安顺市木浪河大桥的检测结果,提出了在主拱圈的拱脚上缘增大截面、下缘增大截面改造为箱形断面,以提高拱脚抵抗负弯矩、正弯矩的承载能力;对其它截面采用拱背增大截面以提高抵抗负弯矩的承载能力,相应也提高了抵抗正弯矩的承载能力;对正弯矩承载能力不足的截面,采用粘贴钢板的加固方法.结果表明:采用这种提载加固的设计方法,达到了提高荷载等级的目的,同时方便施工,便于达到加固效果.

  5. Research on fire-resistant bearing capacity of steel column with wall board in fire%火灾下带墙板钢柱抗火承载力的研究

    Institute of Scientific and Technical Information of China (English)

    陈雷; 徐雁飞

    2011-01-01

    与ALC墙板相连的高频焊接H型钢柱与单纯钢柱的抗火承载力将会有所差别,文章通过有限元分析,研究了墙板对火灾下钢柱的抗火承载力影响和钢柱在火灾下的特性;将有限元分析结果与规程计算结果进行比较,验证了有限元分析的可靠性,并在此基础上分析了荷载比和截面温度梯度,为带墙板的钢柱抗火设计提供依据.%The fire-resistant bearing capacity of high-frequency welded H steel column with ATC wall board attached is different from that of pure steel column. Through the finite element analysis, the effect of wall board on the fire-resistant bearing capacity of steel column in fire is studied as well as the properties of steel column in fire. The results of the finite element analysis are compared with those of the calculation according to related standard, which validates the reliability of the finite element analysis. The relevant parameters are also analyzed including bearing ratio and section temperature gradient. The study can promote the fire-resistant design of steel column with wall board.

  6. 大直径钻孔灌注桩的竖向承载性能%Vertical bearing capacity of large-diameter bored pile

    Institute of Scientific and Technical Information of China (English)

    刘念武; 龚晓南; 俞峰

    2015-01-01

    T he self‐balancing test w as conducted on tw o 2 .2 m diameter drilled piles in order to analyze the bearing capacity of large diameter bored piles .The test results were compared with in‐situ test results . Results show that the change of load‐displacement of pile with post‐grouting is slower than pile without post‐grouting .The end resistance reached the limit state when pile tip displacements approached 20 mm (1% D ,D is the pile diameter) .The side resistance increased firstly and maintained a stable trend with the increase of pile‐soil relative displacement .The critical displacement was 1 .5‐3 .0 mm .Post‐grouting can improve the side resistance over a certain depth from the pile tip ,and the improvement in round gravel mixed pebble bed is 18 percent . Resistive loads up and dow n the side of the load cell is different and transformation coefficient is 0 .92 and 0 .91 , respectively . Side resistance and undrained vane‐shear strength has a linear relationship and has a better goodness of fit .The ultimate side resistance of round gravel mixed can be estimated by dynamic sounding (63 .5 kg) hits .%为了分析大直径钻孔灌注桩的承载性能,对2根直径分别为2.2m的钻孔灌注桩开展自平衡试验,将试验结果与原位测试结果进行对比分析.通过对测试结果的分析发现,注浆后荷载箱的向上及向下荷载‐位移曲线的变化更加缓慢,当桩端位移为20 mm(1% D ,其中 D为桩径)左右时,端阻达到极限状态,未注浆桩和注浆桩的极限端阻分别为2834、3561 kPa .桩身侧阻随着桩土相对位移的增大呈先增大后保持稳定的趋势,淤泥质粉土层、黏土夹粉砂层、圆砾混卵石层的侧阻在桩土相对位移为1.5~3.0mm时达到稳定.注浆能够提高桩端以上一定深度的桩身侧阻,圆砾混卵石层中侧阻的提高幅度约为18%.荷载箱上下的侧阻随位移的变化模式不同,未注浆桩

  7. 高强度钢柱高温下承载力数值计算方法%Numerical Method for Load Bearing Capacity of High Strength Steel Columns at Elevated Temperature

    Institute of Scientific and Technical Information of China (English)

    王卫永; 李国强

    2011-01-01

    In order to make fire resistance design of high strength steel columns in building structures, the numerical calculation method on load bearing capacity of high strength steel columns at elevated temperature was investigated. By taking the mechanical property of high strength steel at elevated temperature into consideration, extension was made on the inverse calculation segment length method and the program to compute the load bearing capacity of high strength steel columns at elevated temperature was performed. The program was adopted to compute the load bearing capacity. The results obtained by the program and the finite element analysis were compared and good agreement had been found. The influence of magnitude, distribution mode of residual stress and initial geometry imperfection on ultimate load bearing capacity was analyzed by employing the program. It is shown that the extended method can be is shown used to calculate the load bearing capacity of high strength steel columns at elevated temperature; the magnitude and distribution mode of residual stress had little influence but the geometry imperfection have significant influence on ultimate load bearing capacity.%为了对建筑结构中的高强度钢柱进行抗火设计和验算,研究了高强度钢柱在高温下的极限承载力数值计算方法.考虑温度对高强度钢材力学性能的影响,对常温下钢柱极限承载力计算的逆算单元长度法进行了延伸,编制了高温下高强度钢柱极限承载力计算程序.采用编制的程序对高强度钢柱在高温下的极限承载力进行了计算,将计算结果与有限元分析结果进行了比较,发现吻合较好.分析了高强度钢柱截面上残余应力的分布模式,残余应力大小和柱的初始几何缺陷对极限承载力的影响.研究表明:延伸的逆算单元长度法可以用于高强度钢柱高温下极限承载力计算,残余应力的分布模式和大小对高温下高强度钢柱的极限承载

  8. 输电塔K 节点极限承载力影响因素分析%Analysis on Influence Factor on Ultimate Bearing Capacity of K Node of Power Transmission Tower

    Institute of Scientific and Technical Information of China (English)

    陈加宝; 雷俊方

    2015-01-01

    In order to study characteristics of nodes of power transmission steel tube tower and steel tube angle combined tow-er,finite element software ANSYS was used to establish a 3D entity model of K node of power transmission steel tube angle combined tower. Influence on ultimate bearing capacity of K node by three failure modes of K node,length and thickness of steel angle and length of node plate was analyzed. The results indicates that ultimate bearing capacity of K node of power transmission steel tube angle combined tower obviously increases with increase of thickness of node plate and steel angle. Secondly,thickness of the steel angle is not suitable to be less than 1 0 mm in design. Influence on ultimate bearing capacity of K node by length of node plate and steel angle is small.%为研究输电钢管塔及钢管角钢组合塔节点的特性,采用有限元软件 ANSYS 建立输电钢管角钢组合塔 K节点三维实体模型,分析K节点的三种破坏模式以及角钢长度、角钢厚度和节点板长度对 K 节点极限承载力的影响。结果表明:输电钢管角钢组合塔K节点的极限承载力随着节点板和角钢厚度的增加而显著增大,在设计时角钢厚度不宜小于10 mm;输电塔K节点的极限承载力受节点板长度、角钢长度的影响较小。

  9. 粒料桩复合地基承载力发挥值试验研究%Experimental Study on Efficiency Factor of Bearing Capacity of Granular Pile Composite Foundation

    Institute of Scientific and Technical Information of China (English)

    轩勇; 刘军勇

    2013-01-01

    结合实体公路工程,通过现场试验段土压力监测,计算复合地基承载力发挥值;结合破坏模式,对其复合地基承载力发挥值进行分析.研究结果表明:粒料桩复合地基按照土体先破坏计算的复合地基承载力发挥值,接近现场载荷试验结果,复合地基承载力可通过桩墩间土压力进行计算确定;不论是强夯置换砾石墩还是振动砾石桩,其破坏形式是桩(墩)间土先破坏引起的整个复合地基的破坏.%Combining with substantial highway engineering,efficiency factor of bearing capacity of composite foundation was calculated through soil pressure monitoring at the section for site test and,with failure mode,it was analyzed as well.The study result shows that for granular pile composite foundation,the efficiency factor of bearing capacity calculated in terms of earth mass failure taken place first is close to the result of on-site load test and the bearing capacity may be calculated through soil pressure between piles/piers.In addition,the failure mode is such that the whole composite foundation is destroyed in the event that the soil between piles (piers) is destructed at first,regardless of dynamic replacement gravel pier or vibration gravel pile.

  10. CFRP加固混凝土梁抗弯极限承载力计算方法%Calculating Method of Bending Ultimate Bearing Capacity of CFRP Reinforced Concrete Beam

    Institute of Scientific and Technical Information of China (English)

    林巧吟

    2009-01-01

    The article studies the destroyed form and ultimate status of carbon fiber material strengthened steel reinforced concrete bending members, and puts forward a practical calculation method for the front sectional bending bearing capacity, which can provide the reference for the practical engineering design.%该文对碳纤维材料补强加固钢筋混凝土抗弯构件的破坏形态和极限状态进行了研究,提出了正截面受弯承载力的实用计算方法,可为实际工程设计提供参考.

  11. Experiment Study on Normal Section Bearing Capacity of Masonry Arch?Bridge Reinforced with Composite Arch Ring%复合拱圈加固圬工拱桥正截面承载力试验研究

    Institute of Scientific and Technical Information of China (English)

    乔文靖; 孙克东; 李成华

    2016-01-01

    In order to research on normal section bearing capacity of masonry arch bridge that is strengthened by composite arch ring under cracks of original arch ring,the three sectional models of masonry arch bridge strengthened by composite arch circle are designed,considering the cracks of original arch ring and the mechanical properties of different materials,numerical simulation and experimental research are carried out based on common stress and deformation coordination between the original arch ring and reinforced layer.The results show:When the crack width is 1/4 original arch width,the bearing capacity is 14.5% less than the non crack arch segment;When the crack width is 1/2 original arch width,the bearing capacity is 3 7 .3% less than the non crack arch segment;The bearing capacity decreases in proportion of the increased crack width.%为了研究原拱圈在裂缝作用下,复合拱圈加固圬工拱桥的正截面承载力计算问题,建立了3个复合拱圈加固圬工拱桥节段模型,考虑原拱圈的裂缝和不同材料的力学性能,基于原拱圈和加固层共同受力和协调变形,进行了数值模拟和试验研究.结果表明:当裂缝宽度为原拱圈宽度1/4时,实测承载力比无裂缝拱段减少了14.5%;当裂缝宽度为原拱圈宽度1/2时,实测承载力比无裂缝拱段减少了37.3%,裂缝增大使承载力成比例减小.

  12. Stable bearing capacity coculation of greenhouse structures considering skin effect of covering material%考虑覆盖材料蒙皮效应的温室结构稳定承载力计算

    Institute of Scientific and Technical Information of China (English)

    丁敏; 李密密; 施旭栋; 张鹏; 蒋秀根

    2016-01-01

    The greenhouse is a kind of agriculture production building facilities. It should bear all kinds of loads, including the loads induced by gravity, improper operation, and live loads, such as wind load and snow load. At the present time, a large number of research studies on greenhouse have focused on illumination, temperature, gas and humidity, whereas there are few researches published on greenhouse structures, especially on greenhouse structure design theory taking the supporting role of covering materials into account. It is necessary to carry out the research on space robustness of greenhouse structure by bringing the design work condition into correspondence with the actual work condition. Then three types of greenhouse including Huabei-type greenhouse, venlo greenhouse and sunlight greenhouse, were chosen to be prototypes, and the numerical simulations on the overall collapse process of single hinged frame, whole frame structure, whole frame structure with plate glass covering, whole frame structure with PC board covering, and whole frame structure with membrane covering under windstorm and snowstorm were carried out by using finite element analysis software ANSYS with consideration of geometric imperfections, material nonlinearity and geometric large deformation. The collapse modes of greenhouse structure and the corresponding load-displacement curves were obtained. The stable bearing capacity and the space robustness of greenhouse structures were analyzed under three typical weather disasters. At the same time their ultimate load coefficient and stable bearing capacity coefficient were provided. The results showed that buckling failure mode happens easily for greenhouse structure under vertical snow load, the whole structure bearing capacity was higher for greenhouse structure under horizontal wind load considering skin effect of covering material. It was due to more compression-flexure members existing in greenhouse structure under vertical snow load than

  13. 钢筋混凝土桥墩承载力计算方法讨论%Discussion of Computing Methods for Bearing Capacity of Reinforced Concrete Bridge Piers

    Institute of Scientific and Technical Information of China (English)

    林上顺

    2015-01-01

    在我国山区公路桥梁工程中,钢筋混凝土高桥墩较为常见。对国内外钢筋混凝土高桥墩承载力计算方法进行分析与比较,发现我国公路桥涵设计规范的计算方法还存在不合理之处,且偏于不安全。为此,提出钢筋混凝土高桥墩承载力计算需要进一步研究的内容。%In highway bridge projects in mountainous area of China reinforced concrete high bridge piers are common.This paper analyzes and compares computing methods for bearing capacity of reinforced concrete high bridge piers at home and abroad and finds out that the computing methods in desing codes for China national highway bridges and culverts are irrational and unsafe .For this reasons , the paper proposes the conents to be further researched in computation of bearing capacity of reinforced concrete high brdige piers .

  14. Determining the pile bearing capacity by the curve match method of high strain dynamic testing%确定基桩承载力的高应变实测曲线拟合法

    Institute of Scientific and Technical Information of China (English)

    王秉宇; 崔建波; 王士杰; 孙东岭

    2012-01-01

    采用高应变实测曲线拟合法确定基桩承载力及桩侧摩阻力的分布,通过基桩承载力动、静试验结果的对比,分析了高应变实测曲线拟合法的测试精度和可靠性,探究了高应变动测法确定基桩承载力的误差来源及因由,为合理确定桩基工程设计参数提供可靠保证.%This essay will determine, the bearing capacity of the pile and shaft resistance by the curve match method of high strain dynamic testing. By the pile of bearing capacity of the contrast between the testing results of static loading and dynamic high strain, analyses the reliability and surveying precision of the curve match method and exdores the error sources and reason, which reasonably determine the pile foundation engineering of design parameters.

  15. 工业缝纫机气浮旋梭轴承气膜承载特性分析%Analysis on Load Capacity Properties of Gas Film for Air -Floating Hook Bearings in Industrial Sewing Machine

    Institute of Scientific and Technical Information of China (English)

    吴昱桦; 李军宁; 卢志伟; 刘波; 张君安

    2016-01-01

    Based on analysis of overall mechanism for industrial sewing machine,the surface fitting of gas film height of air -floating hook bearings is carried out through establishment of physical model under eccentric hook shafting.The gas film pressure distribution is obtained based on finite difference method.The change rule of load capacity and gas consumption of air -floating hook bearings is analyzed under different eccentricity,rotational speed and the distance from supply hole to end face.The results show that the gas pressure is same,the eccentricity of the hook shaft is grea-ter,the rotational speed is faster,and the distance from supply hole to end face of bearing is farther with the increase of load capacity and gas consumption.%在对工业缝纫机整体机构分析的基础上,建立了旋梭轴系偏心下的物理模型,对气浮旋梭轴承气膜高度进行曲面拟合,并基于有限差分法获得气膜压力分布。利用气体流量平衡方程及承载力方程求得旋梭轴在不同偏心距、转速、供气孔距轴承端面距离等工况下,气浮旋梭轴承的承载力、耗气量的变化规律。结果表明:在同一供气压力下,旋梭轴偏心距越大、转速越快、供气孔距轴承端面距离越远,承载力越大,耗气量也越大。

  16. Bearing Capacity of Composite Columns of Waste Tires Filled with Granular Material%内填散体材料废弃轮胎叠合体承载能力研究

    Institute of Scientific and Technical Information of China (English)

    王凤池; 高寰; 张倍川; 徐云龙

    2016-01-01

    为提高废弃轮胎在土木工程上的利用率 ,提出利用废弃轮胎环箍约束散体材料 ,形成具有良好载荷能力的叠合体.通过竖向载荷试验 ,测得不同因素对叠合体承载能力和变形特点的影响情况.分析出叠合体的承载力主要与填充材料的性质和轮胎的直径有关 ,实验表明叠合体的承载力与内摩擦角或轮胎的直径呈正相关关系 ,当后者增大时 ,前者也随之增大 ;当叠合体内填充不同的材料时 ,它的横向变形量沿高度分布情况也不同 ,即变形特点与填充材料有关 ;旧轮胎能够提供相当大的环向约束力 ,给出了横向约束力和横向位移的计算公式 ,具有较好的计算精度 ;该叠合体能够承受很大的上部载荷 ,其颗粒材料的抗剪强度和轮胎的环向约束能力被充分发挥.%The treatment of waste tires is gaining more and more attention .In order to improve the utilization of waste tires in civil engineering ,composite column of waste tires was proposed which was used to constrain the granular material thus had good bearing capacity .By vertical loading tests ,effects of various factors on the bearing capacity and deforma-tion properties of composite columns were studied .The bearing capacity was related with diameter of tires and natures of filling material closely .With the increase of the internal friction angle and the tire diameter ,the bearing capacity of com-posite columns increase as well .Deformation features of composite columns relate to the filling material .Different filling materials lead to different distribution of lateral deformation along the height .Waste tires can provide considerable circu-lar confining force ,calculation formula for lateral binding and transverse displacement was given which has higher calcu-lation accuracy .The results showed that the composite columns filling with granular material could play the roles of shear strength of granular material and the confining

  17. Bearing capacity of thin-walled shallow foundations:an experimental and artificial intelligence-based study%基于人工智能的薄壁浅地基的承重能力研究

    Institute of Scientific and Technical Information of China (English)

    Hossein REZAEI; Ramli NAZIR; Ehsan MOMENI

    2016-01-01

    Thin-walled spread foundations are used in coastal projects where the soil strength is relatively low. Developing a predictive model of bearing capacity for this kind of foundation is of interest due to the fact that the famous bearing capacity equations are proposed for conventional footings. Many studies underlined the applicability of artificial neural networks (ANNs) in predicting the bearing capacity of foundations. However, the majority of these models are built using conventional ANNs, which suffer from slow rate of learning as well as getting trapped in local minima. Moreover, they are mainly developed for conventional footings. The prime objective of this study is to propose an improved ANN-based predictive model of bearing capacity for thin-walled shallow foundations. In this regard, a relatively large dataset comprising 145 recorded cases of related footing load tests was compiled from the literature. The dataset includes bearing capacity (Qu), friction angle, unit weight of sand, footing width, and thin-wall length to footing width ratio (Lw/B). Apart fromQu, other parameters were set as model inputs. To enhance the diversity of the data, four more related laboratory footing load tests were conducted on the Johor Bahru sand, and results were added to the dataset. Experimental findings suggest an almost 0.5 times increase in the bearing capacity in loose and dense sands whenLw/B is increased from 0.5 to 1.12. Overall, findings show the feasibility of the ANN-based predictive model improved with particle swarm optimization (PSO). The correlation coefficient was 0.98 for testing data, suggesting that the model serves as a reliable tool in predicting the bearing capacity.%目的:薄壁扩展式地基已被广泛应用于土壤强度相对较低的沿海工程。目前,已有很多学者对其进行了人工神经网络的适用性研究,希望用此对地基的承重能力进行预测。但是这些研究多数是基于传统的人工神经网络,

  18. 陆上风机圆形基础底板承载力计算方法研究%Calculation Method for Bearing Capacity of Circular Foundation Slab Supporting Onshore Wind Turbine

    Institute of Scientific and Technical Information of China (English)

    梅毕祥; 杨敏

    2016-01-01

    不同于常规构筑物基础,陆上风机圆形基础具有受荷动力效应显著、截面尺寸大等特点.以常规构筑物圆板基础破坏模式为基础,使用极限平衡方法,对风机基础在主要破坏模式下的极限荷载进行了理论推导,开展了风机基础截面尺寸、径环向配筋量等参量的影响分析.分析表明,风机圆形基础的承载力由基础外悬挑扇形块破坏模式确定,其他破坏模式不起控制作用;烟囱规范的长悬挑圆形基础承载力计算公式不适用于风机基础设计;本文提出了风机圆形基础承载力的计算公式及相配套的设计建议,可望为风机基础规范的制定和基础工程设计提供有益参考.%Different from conventional building foundation, obvious load dynamic effect and large size of cross-section characterize the circular foundation of onshore wind turbine. Based on the failure patterns of circular slab foundation for conventional building, limiting equilibrium method is adopted to carry out theoretical derivation of limit load on wind turbine foundation in major failure patterns, and make impact analysis of the parameters including the section size and radial reinforcement of wind turbine foundation. The analysis results show that the bearing capacity of circular foundation slab is determined by the failure pattern of fan-shaped cantilever block and other failure patterns do not apply. Code of chimneys includes the calculation formula for the bearing capacity of long-cantilever circular foundation, which isn't suitable for the design of wind turbine foundation. Thus a new formula for calculating the bearing capacity of wind turbine circular foundation and relevant design suggestions are proposed, which may serve as a reference for the establishment of code of wind turbine foundation and the design of foundation engineering.

  19. 轴向荷载对斜桩水平承载特性影响试验及理论研究%Test and theoretical research on influence of axial load on lateral bearing capacity of batter piles

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

      斜群桩受水平荷载作用时,群桩中的基桩受到径向荷载、轴向荷载和弯矩的共同作用。为研究轴向荷载对斜桩水平承载特性的影响,完成了3根单桩以及1组1×2斜桩的大尺寸模型试验。试验结果表明:轴向拉力作用会降低斜桩的水平刚度和极限承载力;而轴向压力作用则会使其水平刚度和极限承载力提高。基于桩侧浅层土体楔形破坏假定,推导了考虑轴向荷载影响的斜桩水平极限土抗力计算公式,提出了桩侧土抗力的p-y曲线方法,并通过模型试验及现场试验验证其合理性。%When batter pile group are under lateral load, the foundation piles in pile group are subjected to radial load, axial load and bending moment. In order to study the influence of axial load on lateral bearing capacity of batter piles, large-scale model tests of three single piles and a 1×2 batter pile group have been conducted in a larger soil tank. It is found that the upward axial force on the pile top decreases the lateral stiffness and the lateral ultimate bearing capacity of batter pile; while the downward axial force enhances the horizontal stiffness and the lateral ultimate bearing capacity of batter pile. Based on the assumption of wedge failure of the shallow soil around piles, considering the influence of axial load on piles, a formula for calculating the lateral ultimate resistance force of soil is deduced. Then, a p-y curve method for resistance force of soil around piles is proposed. Finally, the formula and the proposed p-y curve method for batter pile are verified by model tests and field tests.

  20. 水平荷载作用下裙式吸力基础承载性能研究%Bearing capacity of skirted suction caisson in sand under horizontal monotonic/cyclic loading

    Institute of Scientific and Technical Information of China (English)

    李大勇; 曹立雪; 高盟; 刘炜炜

    2013-01-01

    Traditional suction caisson is an upside down bucket-shaped structure, which is widely used as an alternative to support offshore platforms and mooring floating structures. It currently acts extensively as the foundation of offshore wind turbines. Its lateral bearing capacity plays an important role in the design. To increase the lateral bearing capacity, a new type of suction caisson, the skirted suction caisson, is presented. The skirted suction caisson in sand is investigated in comparison with the traditional suction caisson by u-sing the finite element method under the monotonic and cyclic loading. The corresponding load-deformation curves are obtained. The results show that the horizontal bearing capacity is significantly enhanced to resist the static and cyclic loads due to the additional structure of the skirt.%传统吸力基础是一个单桶结构,被广泛作为海洋平台、漂浮结构的基础,近年来也被推广到海上风电塔架.作为风电塔架基础,要充分提高其水平承载能力.为此,提出一种改进的基础形式一裙式吸力基础.采用Z_SOIL有限元软件,针对砂土地基,从水平单调加载和循环加载两个方面,对传统单桶吸力基础和裙式吸力基础进行了承载性能对比研究,得到了相应的荷载-位移曲线.研究结果表明,裙式吸力基础由于设置了“裙”结构,显著提高了其抵抗水平静载和循环水平动力荷载的能力,并能有效控制基础的水平位移,是值得推广应用的一种新型海洋工程基础形式.

  1. Analysis of ultimate bearing capacity of prestressed concrete box -girder bridge with large -cantilever -wing%大悬臂展翅预应力混凝土宽箱梁桥极限承载力分析

    Institute of Scientific and Technical Information of China (English)

    余晓琳; 贾布裕; 杨铮; 颜全胜

    2015-01-01

    To study the ultimate bearing capacity of the large cantilever structure,an accurate space finite ele-ment model was built for numerical analysis with the background of a prestressed concrete box -girder bridge with large -cantilevev -wing.Taking into account of the geometric nonlinearity and the material nonlinearity, the structure ultimate bearing capacity and the distribution regularity of cracks under three load cases(eccentric concentrated load,symmetrical concentrated load and uniform distributed load)were analyzed.It is concluded that the structure ultimate bearing capacity under the load case of symmetrical load is larger than that under the case of asymmetrical load;the distributions of the stress and cracks under the load case of asymmetrical load are also asymmetrical and cracks are more likely to appear in the root of the cantilever wing.The stress condition of side span is worse than mid -span under uniformly distributed load.%针对大悬臂展翅结构的极限承载能力问题,以某大悬臂展翅预应力混凝土宽箱梁桥为实际工程背景,建立精细的空间有限元模型进行数值分析。考虑结构几何非线性和材料非线性,研究偏心集中荷载、对称集中荷载、均布荷载3种工况作用下,结构的极限承载能力及裂缝的分布规律。结果表明,对称加载形式的极限承载能力大于非对称加载形式的极限承载能力;非对称荷载作用下,桥梁应力及裂缝分布也具有较大非对称性,且悬臂板根部更加容易出现裂缝,均布荷载作用下,桥梁边跨应力状况劣于中跨。

  2. Journal bearing

    Science.gov (United States)

    Menke, John R.; Boeker, Gilbert F.

    1976-05-11

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

  3. 大跨钢桁拱钢-混组合桥面板极限承载力试验%Experiment on Ultimate Bearing Capacity of Steel and Concrete Composite Deck Slab of Long Span Steel Truss Arch Bridge

    Institute of Scientific and Technical Information of China (English)

    卢彭真; 赵人达; 任剑

    2012-01-01

    To assess the ultimate bearing capacity of the steel-concrete composite deck slab subject to highway load, ultimate bearing capacity tests were carried out. According to Saint Venant Principle, by taking the part steel-concrete deck slab in column area with positive and negative bending moments as finite element models of the actual bridge, the study focused on the ultimate bearing capacity of the steel-concrete deck slab in column area with positive and negative bending moments for 2 composite deck slab specimens (model A and model B). The results show that tensile failure has occurred in the concrete slab of model A. The upper and lower flange plates of I beam, web plate and longitudinal reinforcement have not yielded under ultimate load, but steel bottom plate, PBL and lateral reinforcement have yielded before failure. The failure load of model A is 1 750 kN. As for model B, concrete slab has compression failure, PBL has yielded before failure, and the failure load of model B is 2 200 kN. Research results provide reference for design calculation of the ultimate bearing capacity of steel-concrete composite deck slab.%为评估钢一混组合桥面板结构在公路荷栽作用下的极限承载力,对其进行极限承载力性能试验研究。根据圣维南原理,选取正负双向弯矩受力的立柱区部分桥面板作为实桥的有限元分析模型,并试验制作了2个等尺模型试件A和B,用于考察钢一混组合桥面板正负双向弯矩区的极限承载力性能。试验结果表明:模型A混凝土板被拉坏,工.字钢上下翼缘板、腹板以及纵向钢筋始终未屈服,PBL、钢底板以及横向钢筋均在破坏之前屈服,模型A的破坏荷载为1750kN;模型B混凝土板被压坏,PBL在破坏之前屈服,模型B的破坏荷载为2200kN。研究结果可为钢一混组合桥面板极限承栽能力设计计算提供参考。

  4. T形、Y形带内置环肋圆钢管相贯节点承载力计算方法%Calculation method for bearing capacities of internal ring-stiffened tubular T-and Y-joints

    Institute of Scientific and Technical Information of China (English)

    王帆; 陈志进; 刘丁丁; 罗敏; 宁晨; 蓝小艺

    2014-01-01

    为了得到T形、Y形带内置环肋圆钢管相贯节点的承载力计算公式,对528个节点进行参数化分析.结果表明:T形、Y形节点的环肋设置在冠点时,对节点承载力提高率的贡献最小,而设置在距冠点到鞍点距离的0.7~0.8倍时,贡献最大;支管受压时,T形带肋节点承载力提高值随环肋厚度和宽度的增大而增大,但受支主管直径比和主管径厚比的影响较小;T形、Y形带肋节点承载力提高值之比受支主管直径比和环肋厚度、宽度的影响较小,而随支主管夹角的增大呈近似线性增加;考虑主管应力比以及支管拉力的影响时,可沿用现行规范中无肋节点的相关参数.结合现行规范,提出了T形和Y形节点的承载力计算公式,适用性检验结果证明了所提公式的可靠性.%In order to obtain calculation equations for the bearing capacities of internal ring-stiffened tubular T-and Y-joints,parametric analysis for 528 tubular joints is carried out.The results show that for T-and Y-joints,the smallest increase in joints’ bearing capacity occurs when the stiffeners are lo-cated on the crown,while the increases are highest when the stiffeners are located 0.7 to 0.8 times of the distance between the crown and the saddle from the crown.When the brace is under compres-sion,the ring-stiffened T-joints’ bearing capacity increases with the increase of the thickness and the width of the ring-stiffeners,and the effects of the ratio of brace diameter to chord diameter and the ratio of chord diameter to chord thickness are insignificant.The ratio of the increase of the bearing capacity of T-joints to that of Y-joints linearly increases with the increase of the angle between the brace and the chord,and the ratio of brace diameter to chord diameter, as well as the thickness and the width of ring-stiffeners are less effective.The related parameters of the unstiffened joints in exist-ing codes can be

  5. 土工合成材料加筋地基承载力的可靠度分析%Reliability Analysis of Bearing Capacity of Foundation Reinforced with Geosynthetics

    Institute of Scientific and Technical Information of China (English)

    张晓君

    2001-01-01

    首先选用土工合成材料加筋地基承载力的极限状态方程,对随机变量的概率模型进行了分析,最后结合工程实例,采用优化方法进行了复合地基可靠度的计算.%Firstlythe state equation of bearing capacity of foundation reinforced with geosynthetics was Constructed .Secondlythe probabilistic models of parameters treated as stochastic variables were analyzed. Finallyusing a case historythe reliability of composite foundation was calculated by way of microsoft Excel 2000 solver.

  6. 基于接触非线性的金具安全销极限承载力分析%Ultimate Bearing Capacity Analysis of Safety Pin Based on Nonlinear Contact

    Institute of Scientific and Technical Information of China (English)

    鞠彦忠; 蒋菲; 王德弘; 门丽丽; 曾淑珍

    2012-01-01

    基于输电线路防灾减灾金具的设计,考虑金具之间的接触,建立了碗头挂板、联板、安全销的整体有限元模型,采用增量有限元法分析了安全销上的接触应力,验证了模型的正确性.对安全销的应力分布及极限承载力分析表明,通过调整安全销的槽深,可得到不同孔径比下安全销的极限承载力,确定了在外荷载达到塔线分离荷载前实现塔线分离的安全销尺寸,为安全销的改进提供了合理、有效的方法.%Based on the design of safety pin to prevent disasters in transmission lines, the whole finite clement model of bowl head hanging board, yoke plate and safety pin is established by considering the contact among the fittings. The contact stress distribution of the safety pin is analyzed by using incremental finite element method and the correctness of the model is verified. The load-displacement curve of the safety pin is drawn through analysis of the stress distribution and the ultimate bearing capacity of the safety pin. Ultimate bearing capacities in different aperture ratio are obtained by adjusting slot depth. The size of the safety pin, which makes tower-lines separate before external load attaining tower-line separation load, is determined. Thus, it provides a reasonable effective way for improvement of safety pin.

  7. Theoretical solution for time effect of shaft bearing capacity of single pile in soft soils%软土中单桩桩侧承载力时效性理论解

    Institute of Scientific and Technical Information of China (English)

    曹权; 施建勇; 雷国辉; 艾英钵; 陈鸿

    2011-01-01

    以有效应力原理为基础,结合考虑应变软化、桩径和弹性区孔压分布等因素的桩周土固结解,推导出软土中单桩桩侧承载力时效性的理论解.与传统桩的承载力时效性简化分析方法不同,该理论解不仅考虑了多土层地基中各土层刚度指数的差异对固结过程的影响,还考虑了各土层因固结系数不同对孔压消散速率的影响.通过现场不同间歇期的单桩载荷试验测试结果验证了其合理性.%Based on the theory of effective stress, consolidation solution around the pile which is taken into account the influence of strain softening, magnitude of pile radius and range of excess pore water pressure, a theoretical relationship about time-effect of bearing capacity of single pile is developed, which can be used to predict the variation of shaft bearing capacity of a jacked-in pile with time in saturated soft clay. Different from the traditional way, the effect of different stiffness indices and different consolidation coefficients on the consolidation process in varied clays and highly stratified deposits are considered in the new consolidation solution. Besides, the rationality of the solution is verified by the pile load tests in different time periods after installation.

  8. Assembly of supramolecular DNA complexes containing both G-quadruplexes and i-motifs by enhancing the G-repeat-bearing capacity of i-motifs

    Science.gov (United States)

    Cao, Yanwei; Gao, Shang; Yan, Yuting; Bruist, Michael F.; Wang, Bing; Guo, Xinhua

    2017-01-01

    The single-step assembly of supramolecular complexes containing both i-motifs and G-quadruplexes (G4s) is demonstrated. This can be achieved because the formation of four-stranded i-motifs appears to be little affected by certain terminal residues: a five-cytosine tetrameric i-motif can bear ten-base flanking residues. However, things become complex when different lengths of guanine-repeats are added at the 3′ or 5′ ends of the cytosine-repeats. Here, a series of oligomers d(XGiXC5X) and d(XC5XGiX) (X = A, T or none; i < 5) are designed to study the impact of G-repeats on the formation of tetrameric i-motifs. Our data demonstrate that tetramolecular i-motif structure can tolerate specific flanking G-repeats. Assemblies of these oligonucleotides are polymorphic, but may be controlled by solution pH and counter ion species. Importantly, we find that the sequences d(TGiAC5) can form the tetrameric i-motif in large quantities. This leads to the design of two oligonucleotides d(TG4AC7) and d(TGBrGGBrGAC7) that self-assemble to form quadruplex supramolecules under certain conditions. d(TG4AC7) forms supramolecules under acidic conditions in the presence of K+ that are mainly V-shaped or ring-like containing parallel G4s and antiparallel i-motifs. d(TGBrGGBrGAC7) forms long linear quadruplex wires under acidic conditions in the presence of Na+ that consist of both antiparallel G4s and i-motifs. PMID:27899568

  9. Bearing capacity of thin-walled steel tube short columns filled with lightweight aggregate concrete under axial load%薄壁钢管轻骨料混凝土轴压短柱承载力分析

    Institute of Scientific and Technical Information of China (English)

    肖海兵; 赵均海; 孙楚平; 彭宁; 孙珊珊

    2012-01-01

    Based on the unified strength theory, considering the effects of the intermediate principal stress and the differences of the multi-axial strength criterion for the lightweight aggregate concrete and common concrete, by introducing parameter αu and/βu, loop tensile stress σθ , longitudinal compressive stress σ, and radial compressiye stress σ of the thin- walled steel tube in ultimate bearing condition were obtained. Thus the calculation formula of ultimate bearing capacity of thin-walled steel tube short columns filled with lightweight aggregate concrete was deduced, and the influence complication was analyzed. Compared with the obtained solution and the test results in reference, good agreement can be found. The results indicate that the unified strength theory has the good applicability in the calculation of ultimate bearing capacity of thin-walled steel tube short columns filled with lightweight aggregate concrete. The results can provide theoretical foundation for the design of thin-walled steel tube filled with lightweight aggregate concrete.%运用统一强度理论,考虑中间主应力的影响,引入参数αu,βu确定薄壁钢管在极限荷载时的环向拉应力σθ、纵向压应力σz和径向压应力σr,并考虑轻骨料混凝土与普通混凝土多轴强度准则差异的影响,推导出薄壁钢管轻骨料混凝土轴压短柱的极限承载力公式,并对影响因素进行了分析。将本文计算结果与文献试验数据进行比较,结果吻合良好,表明将统一强度理论运用于薄壁钢管轻骨料混凝土轴压短柱承载力计算是可行的。该结果为薄壁钢管轻骨料混凝土的优化设计提供了一定的理论依据。

  10. 输电线路沙漠地区偏心装配式基础的承载性能研究%RESEARCH ON BEARING CAPACITY OF ECCENTRIC ASSEMBLY FOUNDATION OF TRANSMISSION LINE IN DESERT AREA

    Institute of Scientific and Technical Information of China (English)

    侯鹏翔; 郑卫锋; 李维

    2016-01-01

    On geogrid reinforced aeolian sand ground in Ningxia, a full-scale in-site comparison experiments of the uplift bearing capacity for eccentric assembly foundation were tested under uplift loading and uplift combined with horizontal loadings.Both the site conditions and the load tests were recorded comprehensively, allowing for a thorough evaluation of the loading-displacement behavior.Based on the displacement of top plane of foundaiton and the soil reaction forces, the mechanism of the the eccentric assembly foundation on reinforced aeolian sand ground was obtained.Through taking geogrid reinforcement and eccentric structure measures, the bearing performance of assembly foundation was significantly improved, which could improve its anti-horizontal bearing capacity and did not reduce the uplift performance.The test result provided useful evidence for its practice in transmission line projects in aeolian sand.%在宁夏毛乌素加筋风积沙地基中开展偏心装配式基础在单上拔、上拔与水平力组合工况下的现场对比试验,通过监测其顶部荷载位移曲线、地表竖向位移及基础底板土压力数据,分析偏心装配式基础的抗拔承载机理。试验表明:采用增强地基稳定的加筋和设置基础偏心的结构措施,可显著改善装配式基础的受力性能,在提高其抗水平承载性能的同时不降低其抗拔性能,为沙漠地区输电线路工程中应用装配式基础提供了试验数据。

  11. Grizzly bear

    Science.gov (United States)

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

    2003-01-01

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

  12. 玻璃钢锚环承载性能的有限元分析%Finite Element Analysis of Bearing Capacity of Glass Fiber Reinforced Plastics Anchor Ring

    Institute of Scientific and Technical Information of China (English)

    刘建月; 崔小朝; 刘伟婧; 郑亚东

    2016-01-01

    通过 ABAQUS 有限元分析软件建立了连续玻璃纤维缠绕的聚酯树脂基玻璃钢锚环的有限元计算模型,对玻璃钢锚环与金属夹片、钢绞线配合使用的支护系统进行了加载分析。通过改变玻璃钢锚环的半锥角,研究了玻璃钢锚环与夹片的锥角搭配对锚具承载性能的影响。计算分析表明,在300 kN载荷作用下,计算模型中锚环纤维方向承载性能良好;轴对称面内最大主应力集中在锚环与夹片接触面附近,此处小范围基体开裂对锚环承载性能影响不大;锚环对称面内剪应力大面积超出基体强度极限,是影响锚环承载性能的主要因素。当夹片半锥角为7°时,玻璃钢锚环半锥角为6.3°~6.5°能改善锚环的应力分布状态,提高锚具的承载能力。%This paper established a finite element calculation model of continuous glass fiber winding and polyester resin GFRP anchor ring with ABAQUS,which conducted a loading analysis on the supporting system consisting of GFRP anchor ring,metal clip and steel strand.A research was made on the influence on the loading capacity of an-chor ring by changing the match of taper angles of GFRP anchor ring and clip.According to the calculation analy-sis,the anchor ring of the calculation model has a good bearing capacity in fiber direction under the load of 300 kN;in the symmetrical plane,the maximum principal stress is concentrated nearby the contact face between anchor ring and clip,and the crack of resin in small scale has small influence on the anchor ring bearing capacity;in sym-metrical plane,a large area of shearing stress of anchor ring surpassing resin ultimate stress is the main factor which can influence the loading capacity of anchor ring.When the half taper angle of clip is 7°and that of GFRP anchor ring is 6.3°~6.5°,the stress distribution and loading capacity of anchor ring can be well improved.

  13. RESEARCH ON DISTORTIONAL BUCKLING BEARING CAPACITY OF COLD-FORMED THIN-WALLED STEEL COLUMNS%冷弯薄壁型钢柱畸变屈曲承载力研究

    Institute of Scientific and Technical Information of China (English)

    姚永红; 武振宇

    2016-01-01

    Cold-formed thin-walled steel has been used widely in building structures due to its many advantages.It has been found that the existing calculated values of distortional buckling bearing capacity of columns can' t reflect the experimental law well, and the calculation process of elastic distortional buckling stress is too cumbersome.The suggested direct strength method considering distortional and global interactive buckling and a rotational restraint calculation formula without iteration used for estimating the elastic distortional buckling stress was presented.The values of distortional buckling bearing capacity calculated by proposed method were safe compared with the experiment data, and decreased with the increasing of the column length, which was in accord with the experimental law.Which provided a reference for revision of Technical Code of Cold-Formed Thin-Walled Steel Structures in the future.%冷弯薄壁型钢构件由于自身的诸多优点,已广泛应用于建筑结构之中.分析发现现有柱试件畸变屈曲承载力计算值不能较好地反映试验规律,并且弹性畸变屈曲应力公式计算过程较繁琐.经过理论分析,提出考虑畸变与整体相关屈曲的直接强度法设计公式,给出无需迭代的转动约束刚度建议公式以用于弹性畸变屈曲应力的计算.通过与试验数据对比发现,所提出的建议公式可以较安全地计算柱试件的畸变屈曲承载力,其计算值随柱长增加而减小,符合试验规律,可为《冷弯薄壁型钢结构技术规范》的修订提供参考.

  14. 冷弯薄壁型钢拼合截面柱轴压承载力计算%Calculation Method for Bearing Capacity of Cold-formed Steel Built-up Columns Under Axial Compression

    Institute of Scientific and Technical Information of China (English)

    周绪红; 李喆; 刘永健; 石宇

    2012-01-01

    In order to investigate bearing capacity of cold-formed steel built-up columns under axial compression, authors used ANSYS finite element program to analyze the cold-formed steel built-up columns at home and abroad. Compared with experimental results, the validity of the finite element method (FEM) was verified. Furthermore, a detailed parametric study by FEM was carried out to mainly determine the influence of cross-section form, cross-section dimension and slenderness ratio of component for the built-up effect. The simplified calculation method to the bearing capacity of cold-formed steel built-up columns under axial compression was extracted. The analytical results show that with the increase of the slenderness ratio, the built-up effect improves. As for these columns connected with screws through web, when width-thickness ratio of flange is certain, with the increase of width-height ratio of cross-section, the integrity of the built-up web increases, which leads the built-up effect to strengthen. But the influences of different areas of cross-sections are not so obvious.%为了研究冷弯薄壁型钢拼合截面柱的轴压承载力,对各国有关冷弯薄壁型钢拼合截面柱的轴压试验进行了ANSYS有限元模拟分析,有限元计算结果与试验结果吻合良好,从而验证了有限元方法的正确性.采用有限元方法分析了构件截面形式、截面尺寸以及长细比对冷弯薄壁型钢拼合截面柱拼合效应的影响,提出了冷弯薄壁型钢拼合截面柱轴压承载力的简化计算方法.分析结果表明:随着长细比的增大,拼合截面柱的拼合效应随之增大.对于主要通过螺钉将腹板进行拼合的构件,当翼缘宽厚比一定时,随着截面宽高比的增大,腹板拼合的整体性增强,从而使拼合效应增大,而截面面积的改变对拼合效应的影响则不是很明显.

  15. Experimental study on pressure bearing capacity of recycled aggregate concrete perforated brick walls%再生混凝土多孔砖墙体受压承载力试验研究

    Institute of Scientific and Technical Information of China (English)

    郭樟根; 徐一凡; 孙伟民; 沈丹; 陈建龙

    2011-01-01

    再生骨料替代率为75%,再生混凝土多孔砖强度等级接近MU10.考察再生混凝土多孔砖墙体的受压性能,通过对2片再生混凝土多孔砖墙体进行轴心竖向荷载作用下的试验研究.结果表明,再生混凝土多孔砖墙体在竖向荷载作用下的破环全过程和普通混凝七多孔砖墙体基本相似,受力全过程分为3个阶段:弹性阶段、裂缝发展阶段以及破坏阶段.偏于安全考虑,再生混凝土多孔砖砌体的轴心受压承载力可参照GB 50003-2010(征求意见稿)中有关砌体受压承载力计算公式进行计算.%The strength grade of recycled concrete perforated brick wall is close to MU1O when the replacement ratio of recycled aggregate is 75%. The compressive performance of the recycled concrete perforated brick wall was investigated by the experimental study on two recycled concrete perforated brick walls under the function of axial vertical loading. The results show that the compression failure process of recycled concrete perforated brick wall is similar to tbat of ordinary concrete brick walls,which was divided into three stages:elastic stage,crack development stage and the destruction phase. For the sake of safety,the calculation of axial pressure bearing capacity of recycled concrete perforated brick wall can be made with reference to the formula for pressure bearing capacity of masonry as specified in standard CB 50003-2010 "Masonry Structure Design Code"(Draft).

  16. 氢腐蚀分层对换热器筒体承载能力的影响%Influence of bearing capacity of heat exchanger shell caused by hydrogen corrosion delaminating crack

    Institute of Scientific and Technical Information of China (English)

    何家胜; 李超; 朱晓明; 陈伟; 路远明; 杨峰

    2013-01-01

    To explore the influence of hydrogen corrosion delaminating crack on the mechanical properties and bearing capacity in operation of the layered heat exchanger shell, the material capability of layered heat exchanger shell was analyzed by using chemical constituents analysis, hardness test, tensile tests, Charpy V-notch pendulum impact test. The finite element method was used to calculate the stress distribution of heat exchanger shell and to discuss the stress intensity factors of crack tip. The results show that the Mn element is lower in the chemical constituents, other elements accord with the National Standards; the material hardness meets the requirements, but the toughness declines obviously. The material of heat layered exchanger shell is deteriorated by the hydrogen corrosion, which destroys the continuity and uniformity of the material, decreases the ultimate strength, but increases the yield-strength ratio. The film stress state is destroyed, and material resistance to crack growth decreases. The hydrogen corrosion delaminating crack causes biggish partial stress and makes bearing capacity of the heat exchanger shell decrease.%为了解换热器筒体发生氢腐蚀分层后,其简体局部材料的性能发生的变化及对换热器运行中的承载能力带来的影响,采用化学成分分析、硬度测试、拉伸试验、夏比V口冲击韧性试验等方法对换热器筒体材料的性能进行了分析;运用有限元分析方法计算了简体分层处的应力分布,并探讨了裂纹尖端应力强度因子的变化情况.研究结果表明:材料化学成分中除Mn元素的含量偏低外,其它元素含量符合国家标准;材料的硬度符合要求,材料的强度极限降低,屈强比上升,韧性明显降低.氢腐蚀分层使换热器筒体材料局部劣化,破坏了材料的均匀性和连续性,破坏了简体的薄膜应力状态,产生了较大的局部应力,使换热器筒体承载能力下降.

  17. Influential Study on Wave Loading to Vertical Bearing Capacity of Wharf Pile Foundation%波浪荷载对码头桩基竖向承载力的影响研究

    Institute of Scientific and Technical Information of China (English)

    袁伟; 闫澍旺; 赵亮

    2011-01-01

    The soil around pile foundation in the wharf will suffer from strength reduction under the cycle wave loading conditions, which would further influence the vertical bearing capacity of the pile foundation. Through the indoor dynamic biaxial GDS to simulate' the cycle wave loading and apply these loads to the soil sample of Tianjin port, the strength reduction laws of soil under the dynamic cycle loads in different depths are obtained. Next, with the help of ABAQUS, combining the working loads with cycle wave loading on the pile foundation, the distribution laws of soil dynamic stress around the pile are analyzed. After synthesizing the dynamic biaxial test, the final results are obtained, which show the soil suffered from strength reduction spreads to the depth up to 5 m, the maximum strength reduction rate nearby soil can reach 85.3 % and the vertical bearing capacity of wharf pile foundation reduction rate is 5.73 % .%码头桩基在波浪循环荷载的长期作用下,桩周一定范围的土体会出现强度弱化,进而会一定程度的影响基桩竖向承载力.该文首先通过室内GDS动态三轴仪对天津港码头地基土样作用模拟的波浪循环荷载,研究不同深度土体受到不同幅值的循环动应力荷载作用后其强度的折减规律.然后通过ABAQUS有限元软件计算模拟码头桩基在上部既有结构相互作用的同时,桩身上部受波浪循环荷载,桩周土动应力的分布规律.结合室内动三轴试验结果,计算得到该码头桩基在波浪循环荷载作用下桩周土体弱化的影响深度约为5m,桩周土体的强度折减率最大达到85.3%,码头桩基竖向承载力的折减率为5.73%.

  18. 基于有效耗能的钢骨超高强混凝土框架节点剩余承载力评估%Calculation and Evaluation of Steel Reinforced High Strength Concrete Frame Node Residual Bearing Capacity After Seismic Action

    Institute of Scientific and Technical Information of China (English)

    常智慧; 闫长旺; 贾金青; 包联进; 王存贵; 刘波

    2016-01-01

    In order to determine the residual bearing capacity of steel reinforced super high strength concrete frame joints after earthquake, this paper established the calculation formula of the residual bearing capacity on the basis of analyzing the seismic damage model by low cycle repeated load test of 12 joint test specimens and discussing the influence of test parameters on the residual bearing capacity. Results show that the calculated results are close to the experimental results. The test parameters have little effect on the decline rate of the load bearing capacity, moreover, the residual bearing capacity increases with the increase of axial compression ratio;specimens with high hoop ratio have higher residual bearing capacity;cross type steel bearing capacity is greater than the remaining test specimens of H-shaped steel; The proposed calculation formula can better reflect the force mechanism of the node, and it can provide theoretical basis for the seismic design and the post earthquake reinforcement of this kind of joints.%为了确定地震作用下钢骨超高强混凝土框架节点的剩余承载力,通过12个节点试件的低周反复荷载试验,在分析地震损伤模型的基础上,建立了剩余承载力计算表达式,并讨论了试验参数对剩余承载力的影响。结果表明:计算结果与试验结果较为接近,试验参数对承载力的下降速率影响不大,剩余承载力随轴压比的增大而增大,配箍率大的试件剩余承载力较高,十字型钢骨试件的剩余承载力大于工字型钢骨试件;所提出的计算公式能较好反映节点的受力机理,可为该类节点的抗震设计和地震后的加固提供理论依据。

  19. 薄膜承载力及其对日光温室结构稳定性能的影响%Load-bearing capacity of films and its effect on structure stability of Chinese solar greenhouse

    Institute of Scientific and Technical Information of China (English)

    丁敏; 施旭栋; 李密密; 剧锦三; 蒋秀根

    2013-01-01

    of film thickness, film span, film pre-tension and load on load-bearing capacity of the single film was analyzed. At the same time, three computation models of solar greenhouse structures, including single hinged arch structure, whole frame structure without film, and whole frame structure with film, were made. The overall failure process and space coefficient of solar greenhouse structure were obtained. The effect of tensioned film on the solar greenhouse structure stability was discussed with parameters such as film thickness, film elastic modulus and film pre-tension changing. The results showed that film dimension and thickness are the main factors affecting its load-bearing properties, and the ratio of film length to film width should also be considered appropriately. Film at 0.2mm thick can prevent disaster caused by extra heavy hail. Tension film was used in favor of wind resistance for solar greenhouse structures, but is not effective for snow resistance. The space coefficient of solar greenhouse structures is least effected by film elastic modulus in all analyzed parameters. The ultimate bearing capacity of the whole frame structure without film is higher than that of the single hinged arch structure under wind and snow loads. The reason is that the stiffness out of plane is enhanced by purelines. Film also plays an important role on improving the ultimate load bearing capacity of greenhouse structures. The fruits are useful to the wind, snow and hail resistant design of solar greenhouse structure covered film.

  20. Decision-Making Model of Power Network Planning with Wind Power Integration Considering Environmental Bearing Capacity%计及环境承载力的风电并网规划决策模型

    Institute of Scientific and Technical Information of China (English)

    曾鸣; 向红伟; 陈英杰; 刘晓立; 刘洋; 邹晖

    2013-01-01

    To maintain the reliability of wind power integration, a four-dimensional environment of decision-making of power network planning with wind power integration is proposed. To consider the features of new energy integration, this article focuses especially on the impact of technical environment and ecological environment on power network planning. Based on the theory of environmental bearing capacity, the decision of power network planning with wind power integration considered is studied, which helps to make a comprehensive and accurate decision of power network planning from aspects of technique, ecology, economy and policy.%为维持风电并网的可靠性,以某区域电网为例,提出了风电并网规划决策的四维环境并分别进行了承压度建模,针对新能源接入特性分析了技术环境和生态环境对电网规划的影响,基于环境承载力理论研究了风电接入电网规划决策,从技术、生态、经济及政策等方面准确地作出电网规划的决策.

  1. Discussion on Determination Method of Bearing Capacity of Angular Gravel Heterogeneity Soil Foundation%探讨确定碎石类非均质土地基承载力的方法

    Institute of Scientific and Technical Information of China (English)

    秦志光; 胡亚龙

    2012-01-01

    通过将载荷试验、重型动力触探试验和瑞雷波法三种试验方法,应用于含有较大块径的碎石土非均质强夯地基试验检测中,将试验结果进行分析,探讨了三种试验方法本身存在的局限性以及在实际应用中试验结果的差异性,重点指出对于碎石土等非均质土地基承载力的判定上使用三种试验方法应注意的问题.%The loading test,heavy dynamic sounding test and rayleigh wave method are used to test heterogeneity dynamic foundation for large-diameter angular gravel.By analyzing the test results, the limitations among three testing methods and the differences of test results in the actual application are discussed, it mainly points that the attentions for decision the bearing capacity of angular gravel etc. heterogeneity soil foundation using three test methods.

  2. The high strain dynamic test method of foundation pile bearing capacity based on genetic algorithm%基于遗传算法的基桩承载力高应变动测法

    Institute of Scientific and Technical Information of China (English)

    闫明

    2014-01-01

    为了准确得到桩基的承载力,在实测曲线拟合方面提出了采取遗传算法来代替传统人工试凑的方法,以通过编程实现自动求解,并结合工程实例试验,将采用遗传算法的拟合结果与静载荷试验结果作了对比,证实了该方法的可行性与可靠性。%In order to get the accurate bearing capacity of pile foundation,this paper used the genetic algorithm to replace the traditional manual test in measured curve fitting method,through the program realization of automatic solution,and combining with practical engineering test,con-trasted the fitting results and static load test results of genetic algorithm,verified the feasibility and reliability of the method.

  3. 圆形浅基础承载力计算新模型及验证%A New Bearing Capacity Calculation Model and Validation of Circular Shallow Foundation

    Institute of Scientific and Technical Information of China (English)

    任志善; 张慧乐; 李从昀

    2009-01-01

    This article assumes that the overall foundation shear damage happened, the sliding surface damage is given, the greatest possible expansion extent of the soil plasticity balance area with the variety of foundation embedment is considered, and both sides of the foundation soil shear strength are taken into account. Circular shallow foundation bearing capacity is theoretically derived with Limit equilibrium method. Using practical engineering examples and numerical simulation with finite element program (ADINA), the correctness of shallow foundation damage model and theoretical derivation are further validated.%通过假定地基发生整体剪切破坏,给出滑动破坏面,考虑地基土的塑性平衡区随着基础埋置深度的不同而扩展到最大可能的程度,并且计及基础两侧土的抗剪强度对承载力的影响,采用极限平衡法,理论上推导出了圆形浅基础承载力.结合工程实例,并利用有限元程序(ADINA)进行数值模拟,进一步验证了浅基础破坏模式的正确性,以及理论推导的可靠性.

  4. Load-bearing capacity of indirect inlay-retained fixed dental prostheses made of particulate filler composite alone or reinforced with E-glass fibers impregnated with various monomers.

    Science.gov (United States)

    Özcan, Mutlu; Koekoek, Winand; Pekkan, Gurel

    2012-08-01

    The load-bearing capacity and failure types of indirect inlay-retained fixed dental prostheses (FDP), made of particulate filler composite (PFC) (Estenia) alone or reinforced with E-glass fibers impregnated with various monomers were evaluated. Indirect inlay-retained FDPs were made between first premolars and first molars (N=30, 10/per group). The inlay parts of the specimens were silica coated and silanized and the specimens were cemented with dual-polymerized resin cement under ultrasonic vibrations. The experimental groups were as follows: Group 1: FRC1 (BR-100, UTMA) + PFC; Group 2: FRC2 (everStick C&B, Bis-GMA/PMMA) + PFC; Group 3: PFC only. The specimens were kept in distilled water at 37 °C for one month and then subjected to fracture strength test. No significant difference was found between the Group 1 and Group 2 FDPs (1357±301 N and 1213±316 N, respectively) (p>0.05) (ANOVA). Group 3 (856±299 N) showed significantly lower results than those of FRC reinforced groups (pinlay cavities. FDPs made of PFC only showed mainly catastrophic fracture of the pontic. In the FRC reinforced groups, predominantly delamination of the veneering was observed. The use of silica coating and silanization in combination with the dual-polymerized resin cement used; under ultrasonic cementation procedure provided sufficient adhesion to withstand static loading forces at the cementation interface, since the failures were predominantly delamination of the veneering in the FRC reinforced groups.

  5. 水平荷载作用下高承台管桩的荷载传递性状及承载力研究%Load Transfer and Bearing Capacity of High-Cap Pipe Piles under Horizontal Load

    Institute of Scientific and Technical Information of China (English)

    雷华阳; 刘利霞; 霍海峰; 陆培毅; 付瑞清; 付海峰

    2012-01-01

    exposing height is less than 1.7m. ultimate horizontal bearing capacity of high cap pipe piles stays constantly, when the exposing height is more than 1. 7 m, it decreases rapidly. Increasing the soil strength, the modulus and diameter of piles could be favorable to the horizontal bearing capacity, while changing the length has little influence.

  6. 长江南京段水污染现状及限排总量%Water pollution and permissible pollution bearing capacity of water function zones in Nanjing reach of Yangtze River

    Institute of Scientific and Technical Information of China (English)

    沈乐

    2013-01-01

    Based on a five-year variation trend of the water quality of 18 water function zones in the Nanjing reach of the Yangtze River, the main pollution sources and the quantity of pollutants discharged into the river were evaluated and analyzed.Suggestions on permissible pollution bearing capacity and pollutant reduction of the water function zones are made.The results of the study show the following: The up-to-standard rates of 83.3% of the water function zones decreased with time during the period from 2005 to 2009.The monitored water quality in 83.3% of the water function zones in 2009 did not reach standards.The main pollution sources were the rivers connecting with the Yangtze River, where the discharge of COD and NH 3-N were, respectively, 65.7% and 49.9% of the total discharge into the river.The discharge of COD and NH 3-N at industrial sewage outlets were, respectively, 20.9% and 25.0% of the total discharge into the river.The permissible pollution bearing capacities of COD and NH3-N in the Nanjing reach of the Yangtze River were 6.59 ×10 4 tons per year and 0.26 ×10 4 tons per year, respectively.Pollutants need to be reduced in the water function zones , including five drinking water source regions, one reserved area, and three fishery, agricultural, and industrial water use areas.The pollutants in the drinking water source regions need to be reduced to as large degree as possible .The reduction rates of COD and NH3-N ranged from 87.0% to 99.0%, and 17.8% to 97.4%, respectively.%  通过长江南京段18个水功能区水质的5 a 变化趋势,分析主要污染源及其入江排污量,提出了各水功能区限制排污总量和入江污染物削减建议.结果表明:长江南京段2005—2009年期间,83畅3%的水功能区达标率均随时间呈下降趋势,2009年83畅3%的水功能区所有的水质监测点均没有达到其水质目标;主要污染源头为通江河道,其 COD、NH3-N 排放量分别占入江排污总量的65畅7%、49畅9%

  7. Discrete Estimation of Beam Column Structure Nappe Lateral Bearing Capacity Under Intense Earthquake%强地震下梁-柱结构推覆侧向承载力离散估计

    Institute of Scientific and Technical Information of China (English)

    肖湘

    2014-01-01

    In the strong earthquake, the accurate estimation of earthquake under the action of the beam column structure nappe lateral bearing capacity, prediction of maximum play beam column structure plastic layer displacement, is building frame design, an important way to enhance the seismic performance of buildings. In the beam column element model is the basis for analysis of frame structural finite element structural mechanics, through multi seismic simulation shaking table system, deformation of foundation dynamic characteristics and the beam column structure system is researched. According to the similarity theory to design the experiment model, considering the SSI effect of the ground motion input, impedance function is obtained based on reasonable selection. The overall yielding mechanism of beam to column structure nappe lat⁃eral discrete estimation method of bearing capacity is proposed, the estimation formula and process analysis is taken. The experimental results show that, the estimation method can accurately judge the layers appear weak layer destruction mecha⁃nisms and the possibility of size, it can predict the structural framework of the Elasto-Plastic Earthquake response, it pro⁃vides reliability of instructing the design of building structure.%在罕见强地震作用下,准确估计强震作用下的梁-柱结构推覆侧向承载力,预测梁-柱结构的最大弹塑性层间位移,是进行建筑框架设计,提高建筑抗震性能的重要方面。在梁-柱单元模型是杆系结构有限元结构力学分析的基础上,通过多子台地震模拟振动台系统,研究地基变形与整个梁-柱结构体系的动力特性,按照相似理论设计试验模型,考虑SSI效应的地震动输入,基于选用的合理的阻抗函数,提出针对具有整体型屈服机制的梁-柱结构推覆侧向承载力离散估计方法,得出估计公式和分析流程。实验结果表明,该估计方法能准确判断各层出

  8. Reliability analysis of foundation bearing capacity based on combined coefficients of variation%基于综合变异系数的地基承载力可靠性分析

    Institute of Scientific and Technical Information of China (English)

    曹宇春; 刘富玲

    2014-01-01

    A simplified reliability and risk analysis method of foundation bearing capacity based on combined coefficients of variation of random variables is proposed using first order second moment technique. The laboratory results and historical published ones of coefficients of variation are taken into consideration as the combined coefficients of variation, which are adopted as the calculated coefficients of variation. The most likely values and their possible ranges of degrees of reliability, probabilities of failure and average expected losses can be obtained using suitable coefficients of variation besides the conventional deterministic analysis. This enables to make optimal design scheme and engineering decision. It has shown that the degrees of reliability of foundation bearing capacity are more sensitive to the internal friction angle compared with the unit weight and the cohesion. The width or area of foundation can be decided upon in terms of the required factor of safety, degree of reliability and probability of failure. Moreover, the combined coefficients of variation of random variables will gradually decrease with the weights increasing of coefficients of variation based on the in-situ investigation results;the corresponding degrees of reliability will increase and the probabilities of failure decrease due to that decrease of combined coefficients of variation.%采用一次二阶矩法,考虑岩土参量变异系数的试验及历史数据,提出了基于综合变异系数的地基承载力简化可靠性与风险分析方法。利用提出的简化可靠性与风险分析方法,可在传统确定性分析的基础上,采用合理的变异系数,分别得到与地基承载力有关的可靠度、破坏概率和平均期望损失的最可能值及其变化范围,为提出优化的地基基础设计方案和工程决策奠定基础;相对于土重度和黏聚力,地基承载力可靠度对于内摩擦角的变化更加敏感;设计时可以

  9. THE NUMERICAL ANALYSIS ON BEARING CAPACITY OF CFG PILE COMPOSITE FOUNDATION UNDER BLASTING%爆破地震作用下CFG桩复合地基动力特性的数值分析

    Institute of Scientific and Technical Information of China (English)

    王维玉; 赵拓; 孟艳杰

    2012-01-01

    Through CFG pile composite foundation dynamic test, a test model was built by using finite element analysis software. The analyses were made for the horizontal acceleration, vertical acceleration, horizontal displacement, vertical displacement and stress, which were dynamic response about the same position different depth and the same depth different locations. The analysis results of the dynamic response were in good agreement with the test results. The factors of dynamic response were studied by numerical simulation. Compared with the dynamic response results of natural foundation, we obtained the conclusions in guiding the significance. A basis is supplied for load bearing capacity, deformation and dynamic characteristics of a CFG pile composite foundation.%该文以CFG桩复合地基在爆破地震作用下的现场动力试验为背景,应用有限元软件建立有限元动力分析的数值模拟模型,从水平加速度、竖向加速度、水平位移、竖向位移及应力几个方面对复合地基同一位置不同深度和同一深度不同位置的动力响应进行了分析,其分析结果与试验结果吻合较好.通过数值模拟对动力响应的影响因素进行了比较研究.并与天然地基的动力响应结果进行对比,得出了有指导意义的结论.为今后探讨CFG桩复合地基的承载力、变形和动力特性提供了研究基础.

  10. 闭口截面压型钢板组合楼板纵向剪切粘结承载力研究%Longitudinal shear-bond bearing capacity study of cold-formed steel deck and concrete composite floors

    Institute of Scientific and Technical Information of China (English)

    张欣颖; 史庆轩

    2012-01-01

    This paper refers to the normative test method advanced by American ASCE Standard for the Structural Design of Composite Slabs, to use ranges of thickness and shearspanlength,compare of the failure mode under the continuous loading. It show that the longitudinal shearing have greater control function to the shorter shearspanlength test specimen. According to practical dataes, the shear-bond coefficients m & k whichs are characterized by concrete tension strength f1 and the equation for calculating the longitudinal shear-bond bearing capacity is advanced in regression analysis. Experiment results show that this type of cold-formed steel deck has better cooperative capability with the concrete and displacement ductility. So it can be used in engineering.%参照美国ASCE组合楼板结构设计规范提出的标准试验方法,采用不同厚度和不同剪跨的试件进行连续加载,对比其纵向剪切粘结破坏形态及受力性能,发现纵向剪力对小剪跨组合板的破坏有较大的控制作用.采集试验数据并进行回归分析,得到以混凝土抗拉强度值f1表征的试验板型剪切粘结系数m,k,进而提出相应的组合楼板纵向剪切粘结承载力计算公式,为工程应用提供参考.试验表明此类压型钢板与混凝土协调工作较好,且延性较大,能够在实际工程中投入使用.

  11. Hydrodynamic bearings

    CERN Document Server

    Bonneau, Dominique; Souchet, Dominique

    2014-01-01

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

  12. Reliability Evaluation of Vertical Bearing Capacity of Post-grouting Bored Piles%后注浆灌注桩桩端竖向承载力可靠性分析

    Institute of Scientific and Technical Information of China (English)

    张杰; 朱晓丽

    2015-01-01

    后注浆钻孔灌注桩目前广泛应用于软土地区中,其承载力较大,沉降较小,因此对其承载力的估算一直受到重视。研究桩端位于砂土层中的桩端后注浆灌注桩竖向抗压承载力可靠度,并编写了相应Matlab程序。考虑到在实际进行可靠度计算时,极限状态方程的确立、随机变量的选择对最后得到的可靠度指标有很大影响,比较了2个随机变量、4个随机变量以及6个随机变量这样3种情况计算同一算例的可靠度指标。对于极限状态方程的确定,本文建立了3种不同的极限状态方程,研究结果发现极限状态方程的选取对可靠度指标的影响较小,可按照实际工程掌握数据选取随机变量。由于进行可靠度研究时,随机变量的均值和标准差都是基于大量数据确定的,会有误差存在,因此研究各个随机变量的敏感性能对实际工程计算可靠度指标的精度提高有所帮助。%Post-grouting bored piles are widely used in soft soil area, whose carrying capacity is large and settlement is small, so estimation of carrying capacity is much accounted of.In this paper, the study was mainly about the reliability evaluation of vertical bearing capacity of the base-grouting bored piles which is lo-cated in the sandy soil and wrote the Matlab program about it.Considering the limit state equation, the choice of the random variables has a great influence on the reliability index.Three conditions, which are of 2 random vari-ables, 4 random variables and 6 random variables, were used to calculate the reliability evaluation of the same example.About selecting limit state equation, three different limit state equations were chosen.And the limit state equation has little effect on reliability evaluation showed in the result.So random variable can be chosen ac-cording to the practical engineering.Considering the mean value and standard deviation of random variables base on mass

  13. Prediction of bearing capacity of CFG piles composite foundation based on wavelet neural network%基于小波神经网络的CFG桩复合地基承载力预测

    Institute of Scientific and Technical Information of China (English)

    李万庆; 闫冠勇; 孟文清; 石华旺

    2011-01-01

    针对BP神经网络学习时间长、收敛速度慢等缺陷,借助小波分析理论,将母小波平移和伸缩构成的小波基作为神经网络的激励函数,通过指导网络的初始化和参数选取,使网络以较简单的拓扑结构实现函数逼近,利用网络训练建立起承载力与其影响因素之间的非线性关系.在相同结构和参数下,与BP神经网络进行分析对比.结果表明:利用小波变换对数据时频局域化分析的能力并结合人工神经网络的自学习功能,使得小波神经网络预测模型具有较强的逼近和容错能力,预测结果比传统的BP神经网络具有更快的收敛速度和更高的精度.%Aiming at the long training time and slow convergence rate of BP neural network, wavelet basis consisted by the translation and stretch of mother wavelet constitutes the activation function of neural network basing on the theory of wavelet analysis. The neural network can use simple topology to approximate function by the guidance of network initialization and parameters selection. The nonlinear relationship between the bearing capacity of CFG piles composite foundation and its main factors is established by using the trained network. Under the same structure and parameters, the prediction results are analyzed and compared with the BP neural network. The result shows that this forecast model makes full use of the wavelet transformation to analysis the data of time - frequency localization and is combined with the self- learning function of artificial neural network,which makes it have a strong a-bility to approach and fault tolerance. The precision and speed by using the trained wavelet neural network is higher and its predicting result is more accurate than that of BP network.

  14. Experimental study on ultimate bearing capacity of axially compressed high strength steel columns%高强钢焊接箱形柱轴心受压极限承载力试验研究

    Institute of Scientific and Technical Information of China (English)

    李国强; 王彦博,; 陈素文

    2012-01-01

    An experimental and theoretical study was presented on ultimate bearing capacity of axially compressed high strength steel columns. The experimental program included 7 welded box columns of 3 different cross sections which were welded with 11 mm-thick Q460 high strength steel plates made in China. The FEA models were built up according to measured sizes of members and tension coupon test results. And initial geometric imperfections and residual stress were taken into account in the FEA models. The experimental result shows that the stability coefficients of welded box columns of high strength steel are higher than the values of type c column curve in GB 50017--2003, and even higher than the values of type b curve for most of the specimens. However, due to the limited test result, the adoption of type b curve needs further verification. The FEA result agrees well with experimental result and could be a valid supplement of test data.%为了研究高强钢中厚板焊接箱形柱的极限承载力,以11 mm厚国产Q460高强钢中厚板制作了7个焊接箱形柱进行轴心受压试验。试件共包含宽厚比8、12、18三种截面,长细比分别为35、50、70。根据试件的实测尺寸、钢材的力学性能建立有限元模型,以初始缺陷的形式考虑了试件的初始挠度、初始偏心及焊接残余应力,分析预测了试件的极限承载力。试验结果表明,高强钢焊接箱形柱稳定系数采用GB 50017—2003《钢结构设计规范》中的c类截面柱子曲线偏保守,试验结果平均曲线更接近b类截面曲线,但仍需进一步验证。分析结果表明,考虑了初始缺陷的有限元模型可准确预测柱的极限承载力,可以作为试验数据的补充。

  15. Prediction of Vertical Ultimate Bearing Capacity and Dynamic Stability Analysis of Super-Long Pile%超长桩竖向极限承载力预测与动力稳定性分析

    Institute of Scientific and Technical Information of China (English)

    姚文娟; 钟倩倩; 郭志兴; 胡宝琳; 仇元忠

    2011-01-01

    Based on the catastrophe theory, a cusp catastrophe model of super-long pile under vertical sta-tic load was established, and the predictor formula was derived. Based on the above analysis, dynamic load was tested, the double cusps catastrophe model of super-long pile under combined load was proposed and used in the analysis of the dynamic stability. Dynamic analysis showed that; The relationship among the amplitude H, the Frequency q and the nonlinear coefficient a was conformed to the double cusps ca-tastrophe model when combined load was applied on super-long pile; there was a certain relationship a-mong the change value of dynamic loading frequency, the previous deformation value of pile and the non-linear coefficient of systems in the process of destabilization of super-long pile; important influence on the response characteristics of super-long pile was obtained under the different dynamic loading path. Project example results show that: the cusp catastrophe model is applicable in predicting vertical ultimate bearing capacity of super-long pile.%应用突变理论建立了超长桩在竖向静荷载作用下的尖点突变模型,推导得到了超长桩的竖向极限承载力预测公式.在静荷载分析的基础上,引入动荷载,建立了超长桩在动静组合荷载作用下的双尖点突变模型,并对其动力稳定性进行了分析.动力分析表明:动静组合荷载作用下超长桩的振幅H、频率关系q与结构非线性系数a三者之间符合双尖点突变模型;超长桩失稳时动载频率的变化值与桩顶预变形值及系统非线性系数有一定的关系;动载作用“路径”对超长桩的响应特征有很大的影响.工程算例表明:应用尖点突变理论对超长桩的竖向极限承载力进行预测具有较好的适用性.

  16. EXPERIMENT STUDIES ON BEARING CAPACITY OF PREFABRICATED STEEL FRAME WITH INCLINED BRACES%装配式斜支撑钢框架承载力性能试验研究

    Institute of Scientific and Technical Information of China (English)

    张爱林; 马靖; 刘学春

    2014-01-01

    New Industrial prefabricated steel frame with diagonal brace is consists of steel truss beam , steel column and steel diagonal brace .The truss beam and diagonal brace are different from the traditional one , whose transferring way of force , mechanical behavior and failure mechanism are not examined .The static test and finite element analysis were done for the single span , single cross and single deck steel frame , aims to study the ultimate bearing capacity of horizontal load , deformation characteristics , failure mechanism and ductility performance .The results of test and analysis show that prefabricated brace frame has strong ability to withstand the horizontal load , the power transmission path is clear , and the damage is located at the mid web member of truss beam .While truss beam is damaged , the frame column and the nodes are in elastic state .The frame can meet the structural requirements of “strong jiont , weak components” and “strong column,weak beam” seismic design requirements .%新型工业化装配式斜支撑钢框架由钢桁架梁、钢立柱、钢斜支撑等构件所组成,该框架的桁架梁和斜支撑不同于传统框架,其传力路径、受力性能、破坏机理未经考证。通过对单榀单跨斜支撑钢框架进行静力试验及有限元模拟分析,旨在研究分析其水平荷载极限承载能力、变形特性、破坏机理及延性性能。试验及分析结果表明:装配式斜支撑钢框架承受水平荷载能力较强,斜支撑将水平荷载传递到桁架梁中部的耗能梁段,传力路径明确合理,破坏位置发生在桁架梁中部腹杆,且破坏时框架柱处于弹性工作状态,满足“强节点,弱构件”及“强柱弱梁”的建筑结构设计要求。

  17. Capacidade de suporte e compressibilidade de um argissolo, influenciadas pelo tráfego e por plantas de cobertura de inverno Bearing capacity and compressibility of argisol (paleudult as affected by traffic and winter cover crops

    Directory of Open Access Journals (Sweden)

    Henrique Debiasi

    2008-12-01

    Full Text Available Uma das medidas mais efetivas na prevenção da compactação do solo é a aplicação de pressões inferiores à sua capacidade de suporte de carga, estimada pela tensão de pré-consolidação (σp. Visando a quantificar o efeito de plantas de cobertura de inverno e do tráfego de rodados de trator sobre a σp e sobre o índice de compressibilidade (IC, vem sendo realizado, desde 2002, um experimento em Eldorado do Sul (RS, em Argissolo Vermelho distrófico franco-argilo-arenoso. Os tratamentos, sob semeadura direta, abrangem três coberturas de inverno (pousio, aveia preta e aveia preta + ervilhaca, substituída em 2006 por nabo forrageiro e duas condições de tráfego (com ou sem tráfego de rodados de trator. No verão, foram semeados milho e soja, em rotação anual. Amostras de solo indeformadas, visando à determinação de algumas propriedades físicas e da σp e do IC, foram coletadas, em junho e novembro de 2006, nas camadas de 0,03-0,06 e 0,12-0,15 m, e equilibradas a diferentes tensões de água. Independentemente da época de avaliação e do tráfego, o pousio resultou nos maiores valores de σp e menores de IC na camada de 0,03-0,06 m. Com menor teor de água no solo, as diferenças na σp entre o pousio e as plantas de cobertura tenderam a diminuir. A realização de sete tráfegos em cinco anos aumentou a σp apenas na superfície do solo, mas não afetou o IC. O uso de plantas de cobertura de inverno, aliado à ausência de tráfego, ao reduzir a densidade do solo e aumentar a macroporosidade, diminuiu a capacidade de suporte de carga e aumentou a susceptibilidade da superfície do solo à compactação.One of the most effective practices in preventing soil compaction is to apply stresses below the bearing capacity of the soil, often estimated by the pre-compression stress (σp. To evaluate the effects of cover crops and tractor traffic on σp and compression index (CI, a field experiment was initiated in 2002 on sandy clay

  18. Research on Bored Bearing Characteristics in Xi’an

    Directory of Open Access Journals (Sweden)

    Zhang Lipeng

    2015-01-01

    Full Text Available To analyze the influence of different soil properties on pile foundation load-bearing characteristics, taking a section of railway in Xi’an and a bridge of Xi’an as test area, and by field static load test to study load transfer characteristics after the test piles under axial pressure, including the distribution of axial force, pile lateral friction, tip resistance traits, ultimate bearing capacity determine, and compare with the theory bearing capacity. Experimental results show that, adjacent soil properties change large, axial force and lateral friction mutation at the junction of corresponding soil layer. Silty clay in different parts is below ground, and its lateral friction plays much difference. Pile lateral friction plays an important role in bearing capacity, but the role of round gravel soil end bearing capacity to pile bearing capacity can’t be ignored. Tests calculate pile bearing capacity significantly larger than standardized formula calculation bearing capacity, which are respectively 55.35% and 119.1%. And give the similar project condition the suggested values of pile bearing capacity and soil friction, to provide reference for similar pile foundation design.

  19. Three-Dimensional Nonlinear Bearing Capacity Analysis of Preloaded Filling Spiral Case%充水保压蜗壳结构联合承载三维非线性分析

    Institute of Scientific and Technical Information of China (English)

    郭涛; 张立翔; 罗竹梅

    2016-01-01

    In order to analyze the cracking treds of concrete,a three -dimensional nonlinear method base on Drucker-Prager model was applied to calculate the elastoplastic damage distribution of preloade filling spiral case structure.The analysis focuses on the damage range of surrounding concrete under overload.The results show that the damage range of surrounding concrete is very small when the internal water pressure reaches the de-sign preloading value.If the overload coefficient exceeds 1.15,the damage range and damage degree on the con-crete increase rapidly.When the coefficient reaches 1.7,the penetrating crack appeared.The top of stay ring, the roots of turbine pier and the entrance of spiral case is the dangerous position of crack initiation and propaga-tion,which should be given more attention.The Drucker-Prager damage plasticity model can well simulation the cracking trends of concrete,and it is very effective to calculate the bearing capacity of concrete structure.%基于Drucker-Prager的弹塑性混凝土本构模型,采用简化算法对充水保压蜗壳进行三维非线性分析,通过超载计算,研究内水压力上升过程中蜗壳外围混凝土可能发生塑性区的危险部位及其塑性区扩展情况.结果表明,在设计内水压力作用下,外围混凝土仍处于弹性工作状态,结构的强度安全性较高;当超载系数大于1.15以后,混凝土塑性区出现并随着内水压力的增加,塑性区迅速增大,当超载系数达到1.7时,出现大面积贯穿性塑性区.座环上下环板附近、机墩根部与水轮机层交界处,由于混凝土较薄,而且属于应力集中区域,始终是塑性区出现的危险部位,应该给予重点关注.另外,当内水压力增高时,蜗壳进口直管段右侧腰部也是塑性区扩展的薄弱部位.

  20. 灌芯率及灌芯位置对配筋砌体墙混凝土框架的极限承载力的影响%Effects of Location Irrigation and Irrigation Rate on Bearing Capacity of Concrete Frame of Reinforced Masonry Wall

    Institute of Scientific and Technical Information of China (English)

    姜俊铭

    2014-01-01

    This paper analyzed, by finite element method, the bearing capacity of concrete frame of reinforced masonry wal of which the frame and the wal is constructed by rigid conn- ection and effects of different location irrigation and irrigation rate on bearing capacity. Research shows that, with the inc- rease of the grouted rate, the carrying capacity of structure tends to increase, but it is also affected by the irrigation of core position.%本文利用有限元方法分析了墙、框刚性连接的配筋砌体墙混凝土框架的极限承载力,以及不同灌芯率和灌芯位置对其承载力的影响。研究表明,随着灌芯率的提高,结构的极限承载力呈逐渐增大趋势,但亦受灌芯位置的影响。

  1. 基于灰色理论和Usher曲线的PHC管桩单桩竖向极限承载力预测%The single pile vertical ultimate bearing capacity prediction of PHC pipe piles based on the grey theory and Usher curve

    Institute of Scientific and Technical Information of China (English)

    王少东; 方光秀

    2014-01-01

    针对利用现行规范公式计算 PHC管桩的竖向极限承载力值存在结果偏低的问题,根据竖向静载荷文献资料,基于灰色理论 GM(1,1)模型和 Usher曲线模型预测单桩的极限承载力,并采用 MATLAB软件实现预测模型算法。工程实例分析表明:灰色预测模型的预测精度与竖向静载试验数据级数选取、预测距离有密切关系;Usher曲线模型对桩极限承载力的预测精度大大高于灰色模型,此结果可为类似工程地质条件下 PHC管桩单桩竖向极限承载力的预测提供借鉴。%In view of the current specification formula for calculating the ultimate bearing capacity of PHC pipe piles vertical value is generally low,according to the literature data of vertical static load,using the theory of grey GM(1,1)model and Usher curve model for predicting ultimate bearing capacity of single pile,to realize the predictive model algorithm by using MATLAB software.The analysis of proj ect instance shows that:the prediction accuracy of grey forecasting model is closely related to the selection of vertical static load test data series and prediction distance;Usher curve model has higher precision than the grey model for the forecast of ultimate bearing capacity of pile,which can provide appreciation for the similar engineering geology PHC pipe piles under the condition of the single pile vertical ultimate bearing capacity prediction.

  2. 非共轴本构模型在吸力式桶形基础承载力数值计算中应用%Application of non-coaxial constitutive model to numerical calculation of bearing capacity of suction bucket

    Institute of Scientific and Technical Information of China (English)

    罗强; 栾茂田; 杨蕴明; 王忠涛

    2012-01-01

    When the suction bucket is subjected to vertical load, it is very easy to induce the integral shear failure of the foundation surrounding the bucket. However, it is not reasonable to ignore the non-coaxial phenomenon, which is caused by the principal stress rotation. Based on the UMAT of FEM software ABAQUS, the non-coaxial model is adopted into the numerical analysis of vertial suction bucket foundationrs bearing capacity problem. The results show that the non-coaxial model has little influence on the integral shear failure mechanism of the foundation, but it not only has a visible softening effect on the bearing capacity-settlement curve, but also decreases the vertical ultimate bearing capacity of the foundation. Itrs safe to take the non-coaxial model into the assessment of the foundation's bearing capacity, which is often determined by the vertical displacement.%当吸力式桶形基础承受竖向荷载作用时,其周围地基容易发生整体剪切破坏,由主应力旋转引起的非共轴现象不容忽视.基于有限元软件ABAQUS二次开发端口UMAT,将非共轴本构模型应用到桶形基础的竖向地基承载力问题的有限元计算中.结果表明,非共轴模型对地基的整体剪切破坏模式没有影响,但是对地基竖向承载力一位移曲线具有显著的软化作用,同时,对地基的竖向极限承载力具有降低作用.如果通过竖向位移来确定地基容许承载力,则非共轴模型得到的计算结果是比较安全的.

  3. Model tests on bearing capacities of suction anchors with taut mooring systems under combined static and cyclic loads%静荷载与循环荷载作用下张紧式吸力锚承载特性的模型试验

    Institute of Scientific and Technical Information of China (English)

    王建华; 刘晶磊; 周扬锐

    2012-01-01

    Load-controlled model tests are conducted to study the bearing capacities of suction anchors with taut mooring systems under combined static and cyclic loads at the optimal loading point using an electric servo loading apparatus developed by the authors. Failure modes of anchors, effects of static loads on cyclic bearing capacities and variations of cyclic bearing capacities with the number of cycles to failure are analyzed based on test results. The following conclusions are drawn. Failure of anchors is the translational failure mode of pullout from the soft stratum if the vertical ultimate resistance acting on anchors is less than the lateral one acting on anchors under combined static and cyclic loads. The displacement along the mooring direction at the loading point is about 0.6 times the anchor diameter when anchors are in the ultimate states under static loads. The cyclic bearing capacity of anchors increases with the increase of static load ratios and the cyclic load withstood by anchors also depends on static load ratio for a specified number of cycles to failure. The cyclic load withstood by anchors is the maximum when the static load ratio is about 0.5. Cyclic bearing capacities of anchors decrease with the increase of the number of cycles to failure for a specified static load ratio. The effect of loading directions on the variation of the cyclic bearing capacity with the number of cycles to failure is not obvious when the loading direction varies from 30 to 40 degrees for a specified static load ratio. The cyclic bearing capacity of anchors is not less than 75% of the static bearing capacity if the static load ratio is greater than 0.5 and the number of cycles to failure is less than 1000.%利用自行开发的电动伺服加载装置,在荷载控制方式下,进行了张紧式吸力锚在最佳系泊点受静荷载作用、受静荷载与循环荷载共同作用时的承载力模型试验。依据试验结果,分析了锚的破坏模式、加载

  4. 基于主成分分析法的福建省资源环境承载力空间差异研究%Study of Spatial Differences of Resource and Environmental Bearing Capacity in Fujian Province Based on Principal Component Analysis

    Institute of Scientific and Technical Information of China (English)

    李庆贺; 伍博炜; 曾月娥; 王佳韡

    2014-01-01

    基于主成分分析法,利用SPSS19.0软件对福建省的资源环境承载力进行了研究分析。结果表明:从总体上看,沿海地区资源环境承载力综合得分大于内陆地区,但沿海地区内部差异较大,其中,厦漳泉地区以及福州地区资源环境承载力明显高于其它地区。为了促进经济社会的可持续发展,必须充分合理地利用资源环境。%Based on principal component analysis , this article analyzes the spatial differences of resource and environmental bearing capacity in Fujian Province by using SPSS19 .0 .The results show that on the whole ,the composite scores of resource and environmental bearing capacity in coastal areas are greater than those in inland areas .But there are obvious differences in coastal areas ,for example ,the areas of Xiamen-Zhangzhou-Quanzhou and Fuzhou get the significantly higher scores than others .Finally ,it points out that the resource and environment must be utilized reasonably and efficiently in order to ensure sustainable socio -economic development .

  5. Station Capacity

    DEFF Research Database (Denmark)

    Landex, Alex

    2011-01-01

    Stations are often limiting the capacity of railway networks. This is due to extra need of tracks when trains stand still, trains turning around, and conflicting train routes. Although stations are often the capacity bottlenecks, most capacity analysis methods focus on open line capacity. Therefore......, this paper presents methods to analyze station capacity. Four methods to analyze station capacity are developed. The first method is an adapted UIC 406 capacity method that can be used to analyze switch zones and platform tracks at stations that are not too complex. The second method examines the need...... for platform tracks and the probability that arriving trains will not get a platform track immediately at arrival. The third method is a scalable method that analyzes the conflicts in the switch zone(s). In its simplest stage, the method just analyzes the track layout while the more advanced stages also take...

  6. Comparison of field and laboratory models of the load bearing capacity in coffee plantations Comparação de modelos de capacidade de suporte de carga do solo de campo e laboratório em plantações de café

    Directory of Open Access Journals (Sweden)

    Piero Iori

    2013-04-01

    Full Text Available Precompression stress is an important property for assessment of tropical soil structure sustainability and is often determined in laboratory tests. The objective of this study was to compare the load bearing capacity models obtained with controlled moisture in laboratory and those obtained with natural field moistures determined a long one year. The evaluation of soil structural sustainability follows four distinct steps: soil sampling in the field, uniaxial compression test of the samples in the laboratory, determination of precompression stress and estimation of the load bearing capacity models. Laboratory estimates of precompression stress were obtained from moisture controlled in laboratory and from natural moisture determined in a field a long one year. In this process, the soil samples were saturated by capillarity with distilled water in laboratory, and after 48 hours, the samples were air dried to obtain the different moisture contents. Then, the precompression stress was determined for this both conditions. To verify if the load bearing capacity models obtained with controlled moisture in laboratory may represent the load bearing models obtained with natural field moisture, these models were compared using the homogeneity test procedure. It was observed that 75% of field models analyzed were similar to the laboratory models. Thus, due to the similarity on the load-bearing capacity models obtained using natural (field or controlled (laboratory moisture contents, the assessment of the soil structure sustainability can be done using both methods.Pressão de pré-consolidação é uma importante propriedade na avaliação da sustentabilidade estrutural do solo e é determinada em testes de laboratório. Neste estudo, objetivou-se comparar modelos de capacidade de suporte de carga obtidos com umidade controlada em laboratório e com umidade natural de campo ao longo de um ano. A avaliação da sustentabilidade estrutural do solo ocorreu em

  7. Conical Magnetic Bearing Development and Magnetic Bearing Testing for Extreme Temperature Environments

    Science.gov (United States)

    Keith, Theo G., Jr.; Jansen, Mark

    2004-01-01

    The main proposed research of this grant were: to design a high-temperature, conical magnetic bearing facility, to test the high-temperature, radial magnetic bearing facility to higher speeds, to investigate different backup bearing designs and materials, to retrofit the high-temperature test facility with a magnetic thrust bearing, to evaluate test bearings at various conditions, and test several lubricants using a spiral orbit tribometer. A high-temperature, conical magnetic bearing facility has been fully developed using Solidworks. The facility can reuse many of the parts of the current high-temperature, radial magnetic bearing, helping to reduce overall build costs. The facility has the ability to measure bearing force capacity in the X, Y, and Z directions through a novel bearing mounting design. The high temperature coils and laminations, a main component of the facility, are based upon the current radial design and can be fabricated at Texas A&M University. The coil design was highly successful in the radial magnetic bearing. Vendors were contacted about fabrication of the high temperature lamination stack. Stress analysis was done on the laminations. Some of the components were procured, but due to budget cuts, the facility build up was stopped.

  8. Analysis of Flexural Behavior and Bearing Capacity of Steel Rebar-Reinforced Steel Fiber-Reinforced Self-Compacting Concrete Beams%钢筋-纤维自密实混凝土梁受弯性能与承载力分析

    Institute of Scientific and Technical Information of China (English)

    宁喜亮; 丁一宁

    2015-01-01

    Bending tests under four point loading were conducted on steel rebar-reinforced steel fiber-reinforced self-compacting concrete ( SFRSCC ) beams , and the corresponding loading-mid-span deflection curve , longitudinal reinforcement strain-longitudinal reinforcement strain curve and failure mode were obtained .The flexural bearing capacity of the beams and the hybrid effect of steel rebar and macro steel fibers were also examined .It is found that the addition of steel fibers can improve the flexural bearing capacity by 10%~42%.Moreover, by taking into ac-count the steel fiber distribution and its force transfer mechanism crossing the crack , a calculation formula is pro-posed to predict the flexural bearing capacity of the beams , and it is compared with the formulas of ACI 544 and CECS 38:2004.Calculation results show that the proposed formula has a better fit with the test results .Thus, it is suitable for the flexural analysis and design of SFRSCC beams .%通过四点弯曲试验得到钢筋-纤维自密实混凝土梁式构件的荷载-跨中挠度曲线、荷载-纵筋应变曲线和破坏形态,对梁式构件的受弯承载力及纤维与钢筋的混杂效应进行了分析。结果表明:钢纤维的加入使钢筋-纤维自密实混凝土梁式构件的抗弯承载力提高了10%~42%。考虑钢纤维跨越裂缝的传力机理及分布情况提出了钢筋-纤维混凝土梁式构件受弯承载力计算公式,并与ACI 544和CECS 38:2004的公式进行了对比,计算结果表明:文中建议公式计算的受弯承载力与试验结果最为接近,可用于钢筋-纤维自密实混凝土梁式构件的受弯分析与设计。

  9. 铁路桥梁群钉组合结构极限承载力和静力行为分析%Analysis on the Ultimate Bearing Capacity and the Statical Behavior of the Composite Structures with Grouped Studs in Railway Bridge

    Institute of Scientific and Technical Information of China (English)

    侯文崎; 叶梅新

    2011-01-01

    Aiming at the application of the composite structures in railway bridges, and according to the results of the push-out tests, the load-slip relationship expressions of Φ13 and Φ22 studs in C50 concrete were acquired by nonlinear least-square fit. Through the ultimate bearing capacity experiments of the composite structures with grouped studs, adopting the proposed FEA simulating method, the reduction of the average ultimate bearing capacity and the shear force distribution of the grouped studs were well studied, as well as the relative influencing factors. Research results reveal that the average ultimate bearing capacity of the grouped studs shows quite big reduction compared with a single stud, which is at most 18%. The shear force distribution of the grouped studs presents an evident non-uniformity with a shape of saddle from top to bottom, which is redistributed as the load increasing. When the load is near to the ultimate bearing capacity, the grouped studs tend to bear the even shear force. The stud stiffness and ways of the load transmission are both important influencing factors on the non-uniform shear force distribution of the grouped studs. The bigger the stud stiffness is, the more the average ultimate bearing capacity of grouped studs will be reduced. The ways of load transmission have little influence on the ultimate bearing capacity of the composite structures with the grouped studs, but have important influence on the non-uniform shear force distribution of grouped studs when the load is at a low level, and the influence will be diminished with load increasing. Analytical results of FEA show good agreement with the experimental results, which demonstrates the correctness and the feasibility of the proposed FEA method.%针对我国铁路桥梁中应用钢-混凝土组合结构,根据推出试验结果,采用最小二乘非线性拟合得到C 50混凝土中φ13和φ22栓钉的荷载-滑移关系式.通过群钉组合结构极限承载力试验,

  10. Porous Squeeze Film Bearing with Rough Surfaces Lubricated by a Bingham Fluid

    Science.gov (United States)

    Walicka, A.; Walicki, E.; Jurczak, P.; Falicki, J.

    2014-11-01

    In the paper the effect of both bearing surfaces and the porosity of one bearing surface on the pressure distribution and load-carrying capacity of a squeeze film bearing is discussed. The equations of motion of a Bingham fluid in a bearing clearance and in a porous layer are presented. Using the Morgan-Cameron approximation and Christensen theory of rough lubrication the modified Reynolds equation is obtained. The analytical solutions of this equation for a squeeze film bearing are presented. As a result one obtains the formulae expressing pressure distribution and load-carrying capacity. A thrust radial bearing is considered as a numerical example.

  11. Porous Squeeze Film Bearing with Rough Surfaces Lubricated by a Bingham Fluid

    Directory of Open Access Journals (Sweden)

    Walicka A.

    2014-11-01

    Full Text Available In the paper the effect of both bearing surfaces and the porosity of one bearing surface on the pressure distribution and load-carrying capacity of a squeeze film bearing is discussed. The equations of motion of a Bingham fluid in a bearing clearance and in a porous layer are presented. Using the Morgan-Cameron approximation and Christensen theory of rough lubrication the modified Reynolds equation is obtained. The analytical solutions of this equation for a squeeze film bearing are presented. As a result one obtains the formulae expressing pressure distribution and load-carrying capacity. A thrust radial bearing is considered as a numerical example.

  12. ANALYSIS OF BEARING CAPACITY OF DOUBLE COLD-FORMED THIN-WALLED C STEEL BACK-TO-BACK COMPOSITE COLUMN WITH PLATE COUPLED%带垫板的双肢背靠背C型钢组合柱承载力分析

    Institute of Scientific and Technical Information of China (English)

    陈明; 芦文文; 刘凯

    2014-01-01

    According to the composite column of double cold-formed thin-walled C steel back to back connected with gusset plate, the test and finite element analysis were carried out to study the stability bearing capacity and failure modes of the specimen under eccentric loading.The elements such as slenderness ratio, gusset plate thickness and gusset plate spacing were discussed , which produced the impacts to composite column ’ s bearing capacity, the relationship between stiffness and axial loading, and the curves of M-φof eccentricity.The results revealed that before the overall instability the local-buckling was occurred, the failure modes were belonging to the in-plane-flexural buckling.The major factors are slenderness ratio, eccentricity and gusset plate spacing which effected the mechanical behavior, while the gusset plate thickness has no obvious impact.In the end, the calculation method of the bearing capacity of the cold-formed thin-walled column was compared with that in“Technical Code of Cold-Formed Thin-Walled Section Steel Structures” ( GB 50018-2002 ) , some suggestions based on the type of composite section column calculation were put forward , and the bearing capacity correction coefficient of the steel composite columns was given .%针对带垫板的双肢背靠背C型钢组合柱,通过试验和有限元模拟分析,研究该类型组合柱在偏心荷载作用下的受力特性,就偏心距、长细比、垫板厚度和间距等参数对组合柱承载力、刚度与轴向荷载的关系和M-φ曲线的影响进行讨论。结果表明:C型钢腹板和受压翼缘在整体失稳之前出现了严重的局部屈曲,组合柱的破坏模式均为弯矩作用平面内的弯曲失稳。长细比、偏心距和垫板间距是影响组合柱受力性能的主要因素,垫板厚度的影响有限。最后与规范GB 50018-2002《冷弯薄壁型钢结构技术规范》规定的柱承载力的计算方法进行对比,对该类组合柱的

  13. CFRP片材加固混凝土连续梁长期受力性能与极限承载力试验%Long-term behaviors and ultimate bearing capacity test of concrete continuous beam strengthened with CFRP laminates

    Institute of Scientific and Technical Information of China (English)

    刘小芳; 李旭

    2011-01-01

    Three rectangular cross-section concrete continuous beam were made, CFRP laminates strenghening, temperature, shrinkage and other factors were considered. The long-term creep behaviors were tested for 648 days, the ultimate bearing capacity of three beams were tested.%制作了3根钢筋混凝土矩形截面连续梁,考虑了CFRP片材加固、温度等因素影响,对3根梁进行长达648d的长期荷载试验,研究了长期荷载作用下的徐变性能,并对3根梁进行了极限承载力试验.

  14. Carrying Capacity

    DEFF Research Database (Denmark)

    Schroll, Henning; Andersen, Jan; Kjærgård, Bente

    2012-01-01

    A spatial planning act was introduced inIndonesia 1992 and renewed in 2008. It emphasised the planning role of decentralised authorities. The spatial planning act covers both spatial and environmental issues. It defines the concept of carrying capacity and includes definitions of supportive...... carrying capacity (SCC) and assimilative carrying capacity (ACC). The act mandates that the latter two aspects must be taken into consideration in the local spatial plans. The present study aimed at developing a background for a national guideline for carrying capacity in Indonesian provinces and districts...... standard or governmental political objective exists. In most cases it was possible to select a set of indicators, including thresholds that are workable in a carrying capacity planning at the local administrative levels. Not all relevant sectors at the decentralized level were included. Indicators of SCC...

  15. Research on ultimate bearing capacity of hybrid fiber reinforced concrete square column%混杂纤维加固混凝土方形短柱极限承载力研究

    Institute of Scientific and Technical Information of China (English)

    尹毓良; 张鸿梅

    2012-01-01

    采用碳纤维布、玻璃纤维布、芳纶纤维布层间混杂加固混凝土方形短柱,就不同加固类型柱体的极限承载力进行对比试验,结果表明混杂纤维的协调匹配能够充分发挥不同纤维的优势,扬长避短,提高承载力,降低成本。%The study adopts the hybrid reinforced concrete square columns with the carbon fiber sheet,the glass fiber and the aramid fiber reinforced plastic sheets,undertakes the comparative experiments on the ultimate loading capacity of columns with various reinforced types,and proves by the result that the coordinative matches of the hybrid fiber can fully exert the advantages of the different fibers,improve the loading capacity and lower the cost.

  16. Actual Analysis of Bearing Capacity of Piles with Super-large Diameter and Deep Penetration Based on Statnamic Method%基于静动法的大直径超长桩承载力实测分析

    Institute of Scientific and Technical Information of China (English)

    王湛; 刘宇峰; 娄学谦; 戴宇文; 桑登峰

    2014-01-01

    Piles with super-large diameters and deep penetration are widely used in ocean and bridge engineering;however,traditional capacity test methods used for such piles have limitations.Focusing on the imperfections of nor-mal static load and Osterberg cell (O-cell)methods,the statnamic testing method is investigated on the basis of the Second Penang Bridge project in Malaysia.The capacities of piles with super-large diameters and deep penetration in sandy strata are studied.Compared with the results of the O-cell method used on the same pile,the applicability of statnamic testing for super-large diameter,deep-penetration piles is analyzed.Results indicate that the equivalent stat-ic capacities resulting from the Unloading Point Method (UPM)and the Segmental Unloading Point Method (SUPM)are 30% larger than the results when using the O-cell method.Because of the influences of dynamic soil re-sistance and pore pressure,the side friction of statnamic testing is also larger than that when using the O-cell meth-od.Therefore,the statnamic method still requires modification.%大直径超长桩在海洋工程和桥梁工程中应用广泛,但目前常用的测试方法均有各自的局限性。针对普通静载费时费力,自平衡测试方法研究不够完善等不足,基于马来西亚槟城二桥工程,采用现场实测方法对砂土地层中大直径超长嵌岩桩的静动法测试进行研究。通过对同一根桩上的自平衡法测试结果进行对比,分析静动法测试大直径超长桩承载力的适用性。通过对比发现,静动法测试结果用传统卸荷点法和分段卸荷点法处理得到的等效静承载力比自平衡法大30%左右;且由于土动摩阻和孔隙水压力影响,静动法测得的桩身摩阻力也大于自平衡测试结果,需要进行修正。

  17. Cryogenic Hybrid Magnetic Bearing

    Science.gov (United States)

    Meeks, Crawford R.; Dirusso, Eliseo; Brown, Gerald V.

    1994-01-01

    Cryogenic hybrid magnetic bearing is example of class of magnetic bearings in which permanent magnets and electromagnets used to suspend shafts. Electromagnets provide active control of position of shaft. Bearing operates at temperatures from -320 degrees F (-196 degrees C) to 650 degrees F (343 degrees C); designed for possible use in rocket-engine turbopumps, where effects of cryogenic environment and fluid severely limit lubrication of conventional ball bearings. This and similar bearings also suitable for terrestrial rotating machinery; for example, gas-turbine engines, high-vacuum pumps, canned pumps, precise gimbals that suspend sensors, and pumps that handle corrosive or gritty fluids.

  18. TOPICAL REVIEW: Superconducting bearings

    Science.gov (United States)

    Hull, John R.

    2000-02-01

    The physics and technology of superconducting bearings is reviewed. Particular attention is given to the use of high-temperature superconductors (HTSs) in rotating bearings. The basic phenomenology of levitational forces is presented, followed by a brief discussion of the theoretical models that can be used for conceptual understanding and calculations. The merits of various HTS bearing designs are presented, and the behaviour of HTS bearings in typical situations is discussed. The article concludes with a brief survey of various proposed applications for HTS bearings.

  19. Study on load-bearing characteristics of a new pile group foundation for an offshore wind turbine.

    Science.gov (United States)

    Lang, Ruiqing; Liu, Run; Lian, Jijian; Ding, Hongyan

    2014-01-01

    Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect.

  20. Study on Load-Bearing Characteristics of a New Pile Group Foundation for an Offshore Wind Turbine

    Directory of Open Access Journals (Sweden)

    Ruiqing Lang

    2014-01-01

    Full Text Available Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect.

  1. Novel nano bearings constructed by physical adsorption

    Science.gov (United States)

    Zhang, Yongbin

    2015-09-01

    The paper proposes a novel nano bearing formed by the physical adsorption of the confined fluid to the solid wall. The bearing is formed between two parallel smooth solid plane walls sliding against one another, where conventional hydrodynamic lubrication theory predicted no lubricating effect. In this bearing, the stationary solid wall is divided into two subzones which respectively have different interaction strengths with the lubricating fluid. It leads to different physical adsorption and slip properties of the lubricating fluid at the stationary solid wall respectively in these two subzones. It was found that a significant load-carrying capacity of the bearing can be generated for low lubricating film thicknesses, because of the strong physical adsorption and non-continuum effects of the lubricating film.

  2. Teddy Bear Stories

    DEFF Research Database (Denmark)

    van Leeuwen, Theo; Caldas-Coulthardt, Carmen

    2014-01-01

    This paper presents a semiotic analysis of a key cultural artefact, the teddy bear. After introducing the iconography of the teddy bear, it analyses different kinds of stories to show how teddy bears are endowed with meaning in everyday life: stories from children's books, reminiscenses by adults...... about their childhood teddy bears, and children's accounts of what they do with teddy bears, both written for school and told 'out of school', The chapter sees teddy bears as artefacts that provide a cultural channeling for the child's need of a transitional object and argues that the meanings of teddy...... bears have traditionally centred on interpersonal relations within the nuclear family, but have recently been institutionalized and commercialized....

  3. Tests of Lead-bronze Bearings in the DVL Bearing-testing Machine

    Science.gov (United States)

    Fischer, G

    1940-01-01

    The lead-bronze bearings tested in the DVL machine have proven themselves very sensitive to load changes as in comparison with bearings of light metal. In order to prevent surface injuries and consequently running interruptions, the increase of the load has to be made in small steps with sufficient run-in time between steps. The absence of lead in the running surface, impurities in the alloy (especially iron) and surface irregularities (pores) decreases the load-carrying capacity of the bearing to two or three times that of the static load.

  4. Conceptual Design and Feasibility of Foil Bearings for Rotorcraft Engines: Hot Core Bearings

    Science.gov (United States)

    Howard, Samuel A.

    2007-01-01

    Recent developments in gas foil bearing technology have led to numerous advanced high-speed rotating system concepts, many of which have become either commercial products or experimental test articles. Examples include oil-free microturbines, motors, generators and turbochargers. The driving forces for integrating gas foil bearings into these high-speed systems are the benefits promised by removing the oil lubrication system. Elimination of the oil system leads to reduced emissions, increased reliability, and decreased maintenance costs. Another benefit is reduced power plant weight. For rotorcraft applications, this would be a major advantage, as every pound removed from the propulsion system results in a payload benefit.. Implementing foil gas bearings throughout a rotorcraft gas turbine engine is an important long-term goal that requires overcoming numerous technological hurdles. Adequate thrust bearing load capacity and potentially large gearbox applied radial loads are among them. However, by replacing the turbine end, or hot section, rolling element bearing with a gas foil bearing many of the above benefits can be realized. To this end, engine manufacturers are beginning to explore the possibilities of hot section gas foil bearings in propulsion engines. This overview presents a logical follow-on activity by analyzing a conceptual rotorcraft engine to determine the feasibility of a foil bearing supported core. Using a combination of rotordynamic analyses and a load capacity model, it is shown to be reasonable to consider a gas foil bearing core section. In addition, system level foil bearing testing capabilities at NASA Glenn Research Center are presented along with analysis work being conducted under NRA Cooperative Agreements.

  5. 长桁与蒙皮脱粘对复合材料加筋板承载能力影响分析%Influence analysis of stringer-skin debonding on load-bearing capacity of stiffened composite panel

    Institute of Scientific and Technical Information of China (English)

    张阿盈; 邓凡尘; 于飞; 袁菲

    2014-01-01

    复合材料结构在制造和使用过程中,难免产生分层损伤,这些损伤都会在不同程度上影响结构的承载能力。针对复合材料加筋板,采用有限元动态显式分析方法,分析长桁与蒙皮脱粘面积对加筋壁板结构屈曲和后屈曲承载能力的影响。在ABAQUS商业化有限元分析软件及其二次开发平台上,利用用户自定义材料(VUMAT)的方法对材料性能进行连续衰减,实现加筋板轴压载荷作用下的渐进式失效分析。建立了脱粘面积与结构承载能力之间的关系,研究结果可为合理制定复合材料构件缺陷验收标准和结构修理容限提供分析依据。%Composite structure is prone to damage in the process of manufactory and service. This damage can influence the load-bearing capability of the structure. In this paper, stiffened composite panel with stringer-skin debonding was studied using finite element dynamic explicit analysis technique. The VUMAT subroutine was adopt to degrade material stiffness consecutively while damage occurred. The progressive analysis of panel under axial compressive load was conducted. Parameter analysis of debonding area was done. The relationship between failure load and debonding size was built. The study of this paper can provide analytic basis for establishing standards of eligibility and repair tolerance for composite structure.

  6. New configuration of bearings for rotor shafts in wind turbines; Neue Lagerkonfiguration fuer Windturbinen-Rotorwellen

    Energy Technology Data Exchange (ETDEWEB)

    Pontius, Thierry [The Timken Company, Canton, OH (United States); Ionescu, Laurentiu

    2010-07-01

    Nowadays, the main bearings of a wind turbine consist of a double-serial pendulum roller bearing as a fixed bearing. This is not an ideal solution. Under this aspect, the authors of the contribution under consideration report on a new configuration of bearings for rotor shafts in wind turbines. A combination of a double-serial tapered roller bearing and a cylinder roller bearing has clear advantages in relation to the use of two pendulum roller bearings: (1) Outstanding radial and axial load carrying capacity; (2) Improved load zone with a balanced distribution of load distribution and an optimized L10 lifetime; (3) Particularly good static and dynamic rigidity.

  7. Ball Bearing Stacking Automation System

    Directory of Open Access Journals (Sweden)

    Shafeequerrahman S . Ahmed

    2013-01-01

    Full Text Available This document is an effort to introduce the concept of automation in small scale industries and or small workshops that are involved in the manufacturing of small objects such as nuts, bolts and ball bearing in this case. This an electromechanical system which includes certain mechanical parts that involves one base stand on which one vertical metallic frame is mounted and hinged to this vertical stand is an in humanized effort seems inadequate in this era making necessary the use of Electronics, Computer in the manufacturing processes leading to the concept of Automated Manufacturing System (AMS.The ball bearing stack automation is an effort in this regard. In our project we go for stack automation for any object for example a ball bearing, be that is still a manual system there. It will be microcontroller based project control system equipped with microcontroller 89C51 from any manufacturer like Atmel or Philips. This could have been easily implemented if a PLC could be used for manufacturing the staking unit but I adopted the microcontroller based system so that some more modification in the system can be effected at will as to use the same hardware .Although a very small object i.e. ball bearig or small nut and fixture will be tried to be stacked, the system with more precision and more power handling capacity could be built for various requirements of the industry. For increasing more control capacity, we can use another module of this series. When the bearing is ready, it will be sent for packing. This is sensed by an inductive sensor. The output will be proceeds by PLC and microcontroller card which will be driving the assembly in order to put it into pads or flaps. This project will also count the total number of bearings to be packed and will display it on a LCD for real time reference and a provision is made using a higher level language using hyper terminal of the computer

  8. Three-dimensional nonlinear simulation analysis and bearing capacity of preloaded filling spiral case%充水保压蜗壳三维非线性仿真与承载力研究

    Institute of Scientific and Technical Information of China (English)

    刘波; 刘健华; 伍鹤皋

    2013-01-01

    A three-dimensional nonlinear simulation was made for analysis of a preloaded filling steel spiral case and its overload computation on the basis of an elastoplastic damage model for concrete and the contact nonlinear theory. The analysis focuses on the behavior of spiral case under water pressure increasing, including stress and reinforcement, damage range of surrounding concrete, displacement of generator pier, and deformation of stay ring. The results show that the spiral case alone almost bears all the internal water pressure and its stress increases very rapidly before the internal water pressure reaches the design preloading value. When internal pressure reaches the design value, the damage range of surrounding concrete and the stress of reinforcement become very small. If the overload coefficient exceeds 1.1, the damage range and damage degree on the surrounding concrete increase rapidly, and the deformations of generator pier and stay ring are significant. The spiral case structure still has a certain margin of safety, however, even when this coefficient reaches 1.5. Three-dimensional nonlinear algorithm can produce a simulation closer to the real case, and it should be adopted in design and study of preloaded filling spiral case structure.%基于混凝土弹塑性损伤模型和接触非线性理论,采用仿真算法对充水保压蜗壳进行三维非线性仿真分析并对其进行超载计算,研究内水压力上升过程中钢蜗壳和钢筋应力、外围混凝土损伤区、机墩结构位移和座环变形的变化规律以及结构的超载能力.结果表明,内水压力达到保压值以前,钢蜗壳几乎处于单独承载状态,应力增加较快;在设计内水压力作用下,外围混凝土局部有较小范围的损伤,钢筋应力较小;超载系数大于1.1以后,外围混凝土的损伤区域和损伤程度迅速增大,机墩和座环的变形明显;但超载系数达到1.5时,蜗壳结构仍然具备一定的安全裕度.三维非

  9. 砂土中吸力式沉箱基础的最大承载力计算方法%Calculation method for maximum bearing capacity of suction caisson foundation in sand

    Institute of Scientific and Technical Information of China (English)

    黎冰; 高玉峰; 沙成明; 童小东

    2012-01-01

    To accurately determine the maximum pull-out loading capacity of suction caisson foundation in sand, the limit equilibrium method is applied. Based on the mechanical characteristics of suction caisson foundation with horizontal translation, a method for three-dimensional limit equilibrium analysis of maximum pull-out loading capacity of suction caisson foundation in sand is proposed. In the proposed method, the development process of earth pressure and shear resistance with displacement, and the characteristics of different earth pressure and side shear resistance over the caisson cross-section are considered. The earth pressure acting on the caisson is assumed to obey the Winkler model and is not in excess of the limiting earth pressure. The shear resistance between caisson and soil is assumed to be linearly proportional to the relative displacement between them before reaching its ultimate value. Fifteen model tests of suction caisson foundation under horizontal loading in sand are conducted to investigate its pull-out behaviors, and the load-displacement curves are obtained. The calculation results by the proposed method agree well with the experimental results, indicating that the proposed method is accurate and effective. Key w%为了准确确定砂土中吸力式沉箱基础的最大承载力,应用极限平衡法对其进行分析.基于吸力式沉箱基础平动时的受力特点,充分考虑土压力和摩擦力的发挥过程以及沉箱横截面上各点土压力大小的不同,提出了一种计算砂土中吸力式沉箱基础最大承载力的三维极限平衡方法.方法中假定沉箱侧壁土压力满足Winkler模型,但其值不超过水平极限土压力值;假定沉箱侧壁与地基土之间的摩擦力在达到最大值之前与两者之间的相对位移成线性正比关系.开展了15组水平荷载作用下吸力式沉箱基础的模型试验,得到了吸力式沉箱基础的荷载-位移曲线.利用所提方法得到的计

  10. EcoBears

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  11. Large deflection analysis of a tension-foil bearing

    Science.gov (United States)

    Elrod, David A.

    1996-01-01

    The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are as follows: rolling or sliding contact within the bearing has life-limiting consequences; and REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's. CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contacts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exist for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. Recently, a new tension-foil bearing configuration has been proposed for turbomachinery applications.

  12. Damper bearing rotordynamics

    Science.gov (United States)

    Elrod, David A.

    1990-01-01

    High side loads reduce the life of the Space Shuttle Main Engine (SSME) High Pressure Oxygen Turbopump (HPOTP) bearings. High stiffness damper seals were recommended to reduce the loads on the pump and turbine end bearings in the HPOTP. The seals designed for use on the pump end are expected to adequately reduce the bearing loads; the predicted performance of the planned turbine end seal is marginal. An alternative to the suggested turbine end seal design is a damper bearing with radial holes from the pressurized center of the turbopump rotor, feeding a smooth land region between two rough-stator/smooth-rotor annular seals. An analysis was prepared to predict the leakage and rotor dynamic coefficients (stiffness, damping, and added mass) of the damper bearing. Governing equations of the seal analysis modified to model the damper bearing; differences between the upstream conditions of the damper bearing and a typical annular seal; prediction of the damper bearing analysis; and assumptions of the analysis which require further investigation are described.

  13. Research on the Mechanical Properties of "Z" Type Double-Decker Ball Bearings.

    Science.gov (United States)

    Yu, Chengtao; Xu, Longxiang; Yu, Xudong

    2014-01-01

    The mechanical model of a "Z" type double-decker ball bearing under the action of radial load is established in this paper on the basis of the Hertz contact theory. According to the security contact angle theory, the influences of inner and outer bearings' internal clearances on the bearing's static load carrying capacity, radial deformation, radial stiffness, and load distribution of balls are analyzed. This model is verified in both stationary and rotational loading experiments. Moreover, the simulation results show that the static load carrying capacity of Z type bearing is smaller than that of either inner bearing or outer bearing that is contributed to compose the Z type bearing. The static load carrying capacity of a Z type bearing reduces with the increase of the inner and outer bearings' internal clearance. These simulation results also indicate that the contact angle of the maximum loaded ball in the outer bearing easily exceeds its security contact angle compared with the inner bearing, which, as the main factor, may cause the Z type bearing to overload and to fail. In this sense, the investigated Z type bearings are unfit to apply to situations with heavy load, high speed, or high precision.

  14. Analysis of Land Ecological Security and Bearing Capacity in New-type Urbanization-Based on Ecological Footprint Model%湖南省新型城镇化的土地承载力与生态安全分析--基于生态足迹模型

    Institute of Scientific and Technical Information of China (English)

    何文举; 罗畅; 李国峰

    2016-01-01

    运用国家生态足迹账户计算方法,对湖南省2012年的各项生物生产性土地类型进行了生态足迹和土地承载力的测算,结果表明,2012年湖南省的人均生态足迹、人均生态赤字、人均土地承载力分别为2.896282公顷、.45216公顷、0.444124公顷,湖南省整个土地生态系统造成的影响已经远超土地承载力的范围并处于危险状态。运用GM(1,1)模型预测2015年、2020年湖南省生态压力指数分别增至5.0559、6.0105,年增长率为3.84%,这表明湖南省土地生态安全状况如果不能有效解善,在未来几年将呈现继续恶化的趋势,也预示十二五背景下湖南省政府“四化两型”战略目标的实现存在一定阻力。文章最后根据湖南省土地承载力现状特点及预测结果,提出了相关建议。%This paper adopts national footprint accounts to calculate and analyze the ecological footprint and ecological bearing capacity in all kinds of biological productive areas of Hunan Province in 2012.The results show that the ecological footprint per capita is 2.896282 hm2,the ecological capacity per capita is 0.293740 hm2,and the ecological deficit per capita is 1.658285 hm2 , indicating that the scope of the impact of the land ecosystem in Hunan province has far exceeded the bearing capacity of land?and is in a dangerous state. Then it applies the GM (1,1)model and predicts that ecological stress index in 2015, 2020 will expand to 5.0559,6.0105,with average annual growth rate of 3.84%, indicating the land ecological security of Hunan Province will be worse in the future and fall into the extremely fragile state, the prediction also reveals the intensive pressure and resistance on the achievement of development strategy“four evolutions,two patterns”under the background of“Twelfth Five Year Plan”of Hunan Province. Finally, combining the status of the land ecological capacity and predictive trend in Hunan Province, this

  15. Ultra-precision bearings

    CERN Document Server

    Wardle, F

    2015-01-01

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

  16. Compliant Foil Journal Bearing Performance at Alternate Pressures and Temperatures

    Science.gov (United States)

    Bruckner, Robert J.; Puleo, Bernadette J.

    2008-01-01

    An experimental test program has been conducted to determine the highly loaded performance of current generation gas foil bearings at alternate pressures and temperatures. Typically foil bearing performance has been reported at temperatures relevant to turbomachinery applications but only at an ambient pressure of one atmosphere. This dearth of data at alternate pressures has motivated the current test program. Two facilities were used in the test program, the ambient pressure rig and the high pressure rig. The test program utilized a 35 mm diameter by 27 mm long foil journal bearing having an uncoated Inconel X-750 top foil running against a shaft with a PS304 coated journal. Load capacity tests were conducted at 3, 6, 9, 12, 15, 18, and 21 krpm at temperatures from 25 to 500 C and at pressures from 0.1 to 2.5 atmospheres. Results show an increase in load capacity with increased ambient pressure and a reduction in load capacity with increased ambient temperature. Below one-half atmosphere of ambient pressure a dramatic loss of load capacity is experienced. Additional lightly loaded foil bearing performance in nitrogen at 25 C and up to 48 atmospheres of ambient pressure has also been reported. In the lightly loaded region of operation the power loss increases for increasing pressure at a fixed load. Knowledge of foil bearing performance at operating conditions found within potential machine applications will reduce program development risk of future foil bearing supported turbomachines.

  17. Estimation of optimum operating point for thrust magnetic bearing with solid magnet

    Institute of Scientific and Technical Information of China (English)

    孙首群; 田育民

    2003-01-01

    A carrying capacity-temperature rise analysis model has been established for analysis of the carrying capacity, temperature rise and carrying capacity-temperature rise characteristic of a thrust magnetic bearing with solid magnet. The results indicate that there must be an optimal operating point for the thrust magnetic beating with solid magnet. The main factors having effect on carrying capacity-temperature rise include static gap and/or ampere-turns. With proper static gap chosen, the bearing can be run near the optimal operating point by adjhusting ampere-turns, thereby optimizing the bearing properties.

  18. 液压高频振动沉桩的饱和土超静孔压及单桩静载特性试验研究%Experimental studies on pore pressure of saturated soils and bearing capacity of piles driven by high-frequency hydraulic vibrator

    Institute of Scientific and Technical Information of China (English)

    邓俊杰; 陈龙珠; 邢爱国; 宋春雨

    2011-01-01

    为解决常规锤击、电动中低频振动法进行桩基施工时引起较为严重的噪声、振动和增大电网负荷等问题,发达国家已在应用液压高频振动施工技术,但沉桩的土动力学机理以及单桩静力荷载-沉降特性等尚缺乏深入的室内外试验研究.利用大吨位液压高频振动锤,在某深厚饱和软土场地对直径500 mm、长度26~29 m的预应力管桩进行了沉桩施工试验,观测了邻近地基土超静孔压随沉桩深度而上升及其后续消散的过程;在休止期满后进行了单桩怪向静载荷试验,并将实测极限承载力与其它常规施工方法的进行了比较分析.试验结果对推广应用液压高频振动沉桩新技术,具有重要的学术和应用参考价值.%To solve the serious noise and vibration problems as well as the high pressure on the capacity of city power supply caused by the existing piling methods with falling hammers and low-frequency electric vibrators, a new piling technique using high-frequency hydraulic vibrators has been used in some developed european countries and the USA.The piling mechanism related to soil dynamics at high frequency and the bearing capacity of piles after installation with the hydraulic vibrators should be investigated in laboratory and construction sites.Using a high-frequency hydraulic vibrator manufactured by a Shanghai machinery company, pre-casted/pre-stressed concrete pipe piles with diameter of 500 mm and length of 26-29 m are driven into the saturated soft ground in the Minhang campus of Shanghai Jiaotong University in China, and the induced excess pore water pressures of adjacent soil at different depths are investigated for about one month.After the specified interruption period of 28 days after piling, the ultimate bearing capacity of each pile is studied by means of the conventional static loading tests and compared with that of piles installed with falling hammers and statically jetting.The experimental

  19. Effect of Bearing Compliance on Thermo-hydrodynamic Lubrication of High Speed Misaligned Journal Bearing Lubricated with Bubbly Oil

    Directory of Open Access Journals (Sweden)

    Basim Ajeel Abass

    2015-03-01

    Full Text Available In the present work the effect of bearing compliance on the performance of high speed misaligned journal bearing lined with a compliant PTFE liner lubricated with bubbly oil at high speeds has been studied. The effect of induced oil film temperature due to shearing effect has been implemented. Hydrodynamic effect of the complaint bearing and the influence of aerated oil have been examined by the classical thermohydrodynamic lubrication theory modified to include the effect of oil film turbulence and oil film temperature with suitable models for bubbly oil viscosity and density. The effect of liner elastic deformation has been implemented by using Winkler model. The effects of variable density and specific heat on the most importantbearing parameters such as maximum pressure, maximum temperature, bearing load carrying capacity and power losses have been investigated.The results obtained show that the oil film pressure and load carrying capacity increased for the bearing lubricated with bubbly oil of higher aeration level and smaller size of air bubbles. Including the effect of elastic deformation of the bearing liner reduces the oil film pressure, load carrying capacity and frictional power loss for the misaligned bearing working at the same circumstances

  20. Gear bearing drive

    Science.gov (United States)

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

    2011-01-01

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

  1. Rolling bearing analysis

    CERN Document Server

    Harris, Tedric A

    2001-01-01

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

  2. My Little Teddy Bear

    Institute of Scientific and Technical Information of China (English)

    钱佳楠

    2005-01-01

    @@ As Valentine's Day came closer,every shop was full of colourful gifts such as cookies in the shape of heart, chocolates,Teddy Bears and so on.When I step into a shop on February 14th,I felt most lonely as I was alone.With mv eves fixed on a lovely Teddy Bear, I wished that someone could send me this stuffed toy.

  3. Stability Analysis of Space Compcoite Structoreand Its Ultimate Bearing Capacity

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    StabilityAnalysisofSpaceCompcoiteStructoreandItsUltimateBearingCapacityZhaoLel;PenJunsheng;DuZhengguo(DepartmentofArchitectur...

  4. Capacity and Capacity Utilization in Fishing Industries

    OpenAIRE

    Kirkley, James E; Squires, Dale

    1999-01-01

    Excess capacity of fishing fleets is one of the most pressing problems facing the world's fisheries and the sustainable harvesting of resource stocks. Considerable confusion persists over the definition and measurement of capacity and capacity utilization in fishing. Fishing capacity and capacity utilization, rather than capital (or effort) utilization, provide the appropriate framework. This paper provides both technological-economic and economic definitions of capacity and excess capacity i...

  5. Magnetic Bearing Consumes Low Power

    Science.gov (United States)

    Studer, P. A.

    1982-01-01

    Energy-efficient linear magnetic bearing maintains a precise small separation between its moving and stationary parts. Originally designed for cryogenic compressors on spacecraft, proposed magnetic bearing offers an alternative to roller or gas bearing in linear motion system. Linear noncontacting bearing operates in environments where lubricants cannot be used.

  6. Modeling of Tilting-Pad Journal Bearings with Transfer Functions

    Directory of Open Access Journals (Sweden)

    J. A. Vázquez

    2001-01-01

    Full Text Available Tilting-pad journal bearings are widely used to promote stability in modern rotating machinery. However, the dynamics associated with pad motion alters this stabilizing capacity depending on the operating speed of the machine and the bearing geometric parameters, particularly the bearing preload. In modeling the dynamics of the entire rotor-bearing system, the rotor is augmented with a model of the bearings. This model may explicitly include the pad degrees of freedom or may implicitly include them by using dynamic matrix reduction methods. The dynamic reduction models may be represented as a set of polynomials in the eigenvalues of the system used to determine stability. All tilting-pad bearings can then be represented by a fixed size matrix with polynomial elements interacting with the rotor. This paper presents a procedure to calculate the coefficients of polynomials for implicit bearing models. The order of the polynomials changes to reflect the number of pads in the bearings. This results in a very compact and computationally efficient method for fully including the dynamics of tilting-pad bearings or other multiple degrees of freedom components that interact with rotors. The fixed size of the dynamic reduction matrices permits the method to be easily incorporated into rotor dynamic stability codes. A recursive algorithm is developed and presented for calculating the coefficients of the polynomials. The method is applied to stability calculations for a model of a typical industrial compressor.

  7. Parametric analysis of ultimate bearing capacity of Q460 high strength steel welded box columns under axial compression%Q460高强钢焊接箱形柱轴心受压极限承载力参数分析

    Institute of Scientific and Technical Information of China (English)

    李国强; 王彦博; 陈素文; 孙飞飞

    2011-01-01

    A parametric analysis on ultimate bearing capacity of fabricated box-section steel columns with the nominal yield strength of 460 MPa was presented.The analysis aims to investigate whether the current design codes for ordinary steel are applicable for high strength steel columns or whether the codes need to be modified to include high strength steel.The calculation program base on numerical integration method(NIM) was written by authors.And the commercial finite element analysis software ANSYS was also adopted for comparison.Numerical models including initial geometric imperfections and residual stresses were verified by test results.The main parameters were width to thickness ratio and column slenderness,which ranged from 7.8 to 17.2 and from 10 to 130 respectively.The effects of residual stresses and initial geometric imperfections on the ultimate bearing capacity with varyious parameters were investigated and discussed.A proposal for the design of high strength steel columns was given based on the comparison of parametric analysis with GB 50017—2003.The curve b,which is higher than the suggested curve c for ordinary steel welded box columns,suits better for the design of box columns fabricated from Q460 steel plates with width to thickness ratio no more than 20.%为研究现有钢结构设计规范是否仍适用于高强钢中厚板焊接箱形柱的设计,对Q460钢轴心受压柱的极限承载力进行了参数分析。采用数值积分法,并与有限元程序ANSYS的数值计算结果作进行对比。数值模型考虑了1/1 000柱长的初始弯曲及由相应截面尺寸残余应力试验提出的残余应力分布简化模型。试件的主要参数为截面宽厚比(7.8~17.2)与柱长细比(10~130)。计算结果表明:考虑相同初始缺陷的有限单元法与数值积分法所得计算结果吻合较好;与普通强度钢柱相比,初始几何缺陷对高强钢焊接箱形柱的极限承载力影响降低,柱的稳定系数

  8. Experimental study on bearing capacity of welded H-section columns using Q460 high strength steel under bending and axial compression%Q460高强度钢材焊接H形截面弱轴压弯柱承载力试验研究

    Institute of Scientific and Technical Information of China (English)

    李国强; 闫晓雷; 陈素文

    2012-01-01

    This paper presented a study on the ultimate bearing capacity of high strength steel columns under eccentric load.Through the tension coupon tests and the measurement of the residual stress of H-section,initial geometric imperfections and ultimate loads of each column,tests on six specimens of welded H-section columns with three different cross sections made by Q460 high strength steel were conducted.The measured ultimate loads were compared with the values predicted by design formulas specified in Chinese codes.FEA models were employed to simulate the results of the tests.Initial deficiencies including geometric imperfection and residual stress were considered in the FEA models.The distribution of the residual stress and the material properties used in FEA models were taken from the tests.Q460 low alloy steel has high strength and high performance plastic property.The distribution of the residual stress of welded H-section columns using Q460 high strength steel and the distribution of the residual stress using ordinary steels were basically identical.The experimental results show that the bearing capacity of welded H-section columns of high strength steel are higher than the values predicted according to the Chinese code for design of steel structures.The results predicted by FEA models fit well with those obtained from the tests.This study provides the basis for the application of Q460 high strength steel in practical engineering.%为了研究高强度钢材中厚板焊接H形截面压弯柱的承载力,采用国产Q460高强度钢材11 mm、21 mm中厚板制作了6个焊接H形截面压弯柱,试件截面自由外伸翼缘板宽厚比分别为7、5、3,长细比分别为40、55、80。通过对Q460低合金高强度钢材的材性测试、3种焊接截面残余应力测试、各试件初始几何缺陷测量及承载力试验,进行了H形截面弱轴压弯构件整体失稳承载力的试验研究,并与采用GB 50017—2003《钢结构设计规范》进行计

  9. Tribology of alternative bearings.

    Science.gov (United States)

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

    2006-12-01

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

  10. 岛状多年冻土地区桥梁桩基回冻后承载力的静载与动测对比试验研究%STATIC AND DYNAMIC CONTRAST TEST FOR BEARING CAPACITY OF REFROZEN BRIDGE PILE FOUNDATION IN PATCHY PERMAFROST REGIONS

    Institute of Scientific and Technical Information of China (English)

    宇德忠; 程培峰; 季成; 崔志刚

    2015-01-01

    为了准确掌握岛状多年冻土地区桥梁钻孔灌注桩的回冻时间及桩基回冻后的承载力,在岛状多年冻土地区选择2个试验地点,每个试验地点浇筑了2根15 m长的试验桩,并在其中一根试验桩处布设温度监测系统,采集桩基回冻过程中的温度数据,根据温度监测结果判断桩基回冻状态,在桩基完成回冻后进行静载与动测试验,测出桩基极限承载力。监测及试验结果表明:试验桩所在区域岛状多年冻土地温约为-1.9℃,桩基完成回冻后桩身内部温度与桩侧1 m处的土体温度变化趋势相同,相同深度处的温差小于0.1℃;用静载法实测出的各土层回冻后的桩侧摩阻力值修正高应变动测法桩–土力学模型中的土层参数,计算曲线与实测曲线拟合较好;动测与静载试验所得到的桩基极限承载力误差为3.91%,试验结果相符合。研究成果可为类似冻土条件下的桩基设计及承载力检测提供理论依据。%To accurately know the refreezing time and capacity of the bridge bored pile constructed in polygonal permafrost regions,two test sites were chosen. Within each site,two 15 m test piles were built. The temperature monitoring system was established in one of the two sites to record and monitor the pile refreezing process. Based on the refreezing condition,static load and dynamic load tests were performed to determine the bearing capacity of the pile. Test results indicate that the mean permafrost temperature is-1.9℃. The trend of temperature change within the pile in refreezing process is similar to that of the permafrost temperature change 1 m beside the pile, which indicates that the difference of temperature change is smaller than 0.1℃. The calculated pile capacity fits well with the testing data by introducing the refreezing pile lateral frictional parameter to modify the soil mechanical model. The capacity error obtains from static load test

  11. On The Modeling Of Hybrid Aerostatic - Gas Journal Bearings

    DEFF Research Database (Denmark)

    Morosi, Stefano; Santos, Ilmar

    2010-01-01

    Gas journal bearing have been increasingly adopted in modern turbo-machinery applications, as they meet the demands of operation at higher rotational speeds, in clean environment and great efficiency. Due to the fact that gaseous lubricants, typically air, have much lower viscosity than more...... conventional oil bearings, carrying capacity and dynamic characteristics of passive systems are generally poorer. In order to enhance these characteristics, one solution is to employ active control strategies. The present contribution presents a detailed mathematical modeling for active lubrication...... of a compressible fluid film journal bearing. Control forces are generated by injecting pressurized air into the bearing gap through orifices located on the bearing walls. A modified form of the compressible Reynolds equation for active lubrication is derived. By solving this equation, stiffness and damping...

  12. Radial Halbach Magnetic Bearings

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2009-01-01

    Radial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Radial Halbach magnetic bearings are based on the same principle as that of axial Halbach magnetic bearings, differing in geometry as the names of these two types of bearings suggest. Both radial and axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control. Axial Halbach magnetic bearings were described in Axial Halbach Magnetic Bearings (LEW-18066-1), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), page 85. In the remainder of this article, the description of the principle of operation from the cited prior article is recapitulated and updated to incorporate the present radial geometry. In simplest terms, the basic principle of levitation in an axial or radial Halbach magnetic bearing is that of the repulsive electromagnetic force between (1) a moving permanent magnet and (2) an electric current induced in a stationary electrical conductor by the motion of the magnetic field. An axial or radial Halbach bearing includes multiple permanent magnets arranged in a Halbach array ("Halbach array" is defined below) in a rotor and multiple conductors in the form of wire coils in a stator, all arranged so the rotary motion produces an axial or radial repulsion that is sufficient to levitate the rotor. A basic Halbach array (see Figure 1) consists of a row of permanent magnets, each oriented so that its magnetic field is at a right angle to that of the adjacent magnet, and the right-angle turns are sequenced so as to maximize the magnitude of the magnetic flux density on one side of the row while

  13. Partial tooth gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2010-01-01

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

  14. WORK PRINCIPLE AND CHARACTERISTIC ANALYSES OF HYDROSTATIC BEARING

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Aiming at the new characteristic of water hydraulic system, a kind of hydrostatic bearing with a concentric gap damper is introduced. The lubricative film thickness of the hydrostatic bearing possesses inflexibility and the loading capacity is just determined by the geometrical dimension of the piston-slipper subassembly and has no relation with system pressure, viscosity and temperature of water and speed of rotor. Theoretical analyses and the verification of scheme done at the test rig show that the hydrostatic bearing with a concentric gap damper is especially fit for water hydraulic components.

  15. The Little Bear

    Institute of Scientific and Technical Information of China (English)

    林战峰; 乐伟国

    2007-01-01

    @@ 一、故事内容 A little bear has a magic stick.It can make his wishes come true. One day,the little bear is walking in the forest.He sees a bird.It is flying in the sky.It has two beautiful wings."I want two beautiful wings.I wish I can fly like a bird,"he says to the magic stick.Two beautiful wings come out from his back and he can fly like a bird now.He is very happy.

  16. Modular gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2009-01-01

    A gearing system using modular gear bearing components. Each component is composed of a core, one or more modules attached to the core and two or more fastening modules rigidly attaching the modules to the core. The modules, which are attached to the core, may consist of gears, rollers or gear bearing components. The core orientation affects the orientation of the modules attached to the core. This is achieved via the keying arrangement of the core and the component modules that attach to the core. Such an arrangement will also facilitate the phase tuning of gear modules with respect to the core and other gear modules attached to the core.

  17. Method to Increase Performance of Foil Bearings Through Passive Thermal Management

    Science.gov (United States)

    Bruckner, Robert

    2013-01-01

    This invention is a new approach to designing foil bearings to increase their load capacity and improve their reliability through passive thermal management. In the present case, the bearing is designed in such a way as to prevent the carryover of lubricant from the exit of one sector to the inlet of the ensuing sector of the foil bearing. When such passive thermal management techniques are used, bearing load capacity is improved by multiples, and reliability is enhanced when compared to current foil bearings. This concept has recently been tested and validated, and shows that load capacity performance of foil bearings can be improved by a factor of two at relatively low speeds with potentially greater relative improvements at higher speeds. Such improvements in performance with respect to speed are typical of foil bearings. Additionally, operation of these newly conceived bearings shows much more reliability and repeatable performance. This trait can be exploited in machine design to enhance safety, reliability, and overall performance. Finally, lower frictional torque has been demonstrated when operating at lower (non-load capacity) loads, thus providing another improvement above the current state of the art. The objective of the invention is to incorporate features into a foil bearing that both enhance passive thermal management and temperature control, while at the same time improve the hydrodynamic (load capacity) performance of the foil bearing. Foil bearings are unique antifriction devices that can utilize the working fluid of a machine as a lubricant (typically air for turbines and motors, liquids for pumps), and as a coolant to remove excess energy due to frictional heating. The current state of the art of foil bearings utilizes forced cooling of the bearing and shaft, which represents poor efficiency and poor reliability. This invention embodies features that utilize the bearing geometry in such a manner as to both support load and provide an inherent and

  18. Influence of load capacity on hydrostatic journal support deformation in finite element calculation

    Institute of Scientific and Technical Information of China (English)

    邵俊鹏; 张艳芹; 李永海; 于晓东; 姜辉

    2008-01-01

    Based on the application of the four-oil-pad radial hydrostatic bearing in heavy equipments, the deformation of the four-oil-pad radial hydrostatic bearing was calculated by using the finite element method. The formula of film stiffness, film thickness and carrying capacity were established; the influence of the main parameters, such as load, load area and deformation on the supportability was analyzed; and the capacity of the two kinds of bearings was compared. The result shows that the carrying capacity of typeⅠ is prior to that of type Ⅱ . Calculations provide a theoretical basis for the bearing choosing and structure designing in the actual project.

  19. Silver Bear for Screenplay

    Institute of Scientific and Technical Information of China (English)

    LIU YUNYUN

    2010-01-01

    @@ Chinese director Wang Quan'an won the Silver Bear Prize at the 60th Berlin International Film Festival that lasted during February 11 to 21 tor the best screenplay for his movie Apart Together.The film also opened the festival.

  20. Hybrid superconductor magnet bearings

    Science.gov (United States)

    Chu, Wei-Kan

    1995-01-01

    Hybrid superconductor magnet bearings (HSMB's) utilize high temperature superconductors (HTS's) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS's, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, we present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

  1. Analysis of a Thrust Bearing with Flexible Pads and Flexible Supports

    DEFF Research Database (Denmark)

    Klit, Peder; Thomsen, Kim

    2007-01-01

    A theoretical analysis of a hydrodynamic thrust bearing is presented. The bearing investigated is used in an ndustrial product. The lubricant is water, but the results are valid also for other lubricants.At first the results from a 1-dimensional model for the fluid film forces and the associated ...... improvements in load carrying capacity is presented....... deformation of the bearing geometry is presented. This model enlightens the influence of pad flexibility and support location and flexibility. Subsequently results from a 2-dimensional model of the bearing is presented. The model is used to carry out an optimization of the bearing design, and the obtained...

  2. Magnetic bearings for cryogenic turbomachines

    Science.gov (United States)

    Iannello, Victor; Sixsmith, Herbert

    1991-01-01

    Magnetic bearings offer a number of advantages over gas bearings for the support of rotors in cryogenic turboexpanders and compressors. Their performance is relatively independent of the temperature or pressure of the process gas for a large range of conditions. Active magnetic bearing systems that use capacitive sensors have been developed for high speed compressors for use in cryogenic refrigerators. Here, the development of a magnetic bearing system for a miniature ultra high speed compressor is discussed. The magnetic bearing has demonstrated stability at rotational speeds exceeding 250,000 rpm. This paper describes the important features of the magnetic bearing and presents test results demonstrating its performance characteristics.

  3. Numerical Analysis of Turbocharger’s Bearing using Dynamic Mesh

    Directory of Open Access Journals (Sweden)

    J. Moradi Cheqamahi

    2016-01-01

    Full Text Available Journal bearings are widely used in different machineries. Reynolds equation is the governing equation to predict pressure distribution and load bearing capacity in journal bearings. There are many analytical and numerical methods for solving this equation. The main disadvantage of these methods is their inability to analyze complex geometries. In this paper, a comprehensive method based on dynamic mesh method is developed to solve the conservation equations of mass, momentum and energy. This method has smaller error compared to other techniques. To verify the accuracy of this method, the bearings with different length to diameter ratios are analytically and numerically analyzed under different loads and compared with each other. In continue, the turbocharger’s bearing is numerically simulated and the effects of rotational speed change are studied. Finally, the turbocharger’s bearing with four axial grooves are simulated. The simulations results show that adding grooves to the turbocharger’s bearing causes the bearing eccentricity ratio and lubricant flow rate to increase and the attitude angle, rate of temperature rise and frictional torque to decrease.

  4. Magnetic bearings grow more attractive

    Science.gov (United States)

    1993-10-01

    Advances in materials and electronics have enabled designers to devise simpler, smaller magnetic bearings. As a result, costs have dropped, widening the applications for these very-low-friction devices. Avcon (Advanced Controls Technology) has patented a permanent-magnet bias actively controlled bearing. Here high-energy rare earth permanent-magnet materials supply the basic bearing load levitation, while servo-driven electromagnets generate stabilization and centering forces for motion contol. Previous heavy-duty magnetic bearings used electromagnets entirely for suspension and control, which led to large bearings and control systems with higher power requirements. Avcon has developed several types of permanent-magnet bias bearings. The simplest is the radial repulsion bearing. Avcon's homopolar permanent-magnet bias active bearing is the most versatile of the company's designs.

  5. Adaptação de métodos semi-empíricos para estimar capacidade de carga de estacas de pequeno diâmetro no solo de Londrina, Estado do Paraná = Adaptation of the semi-empiric methods to calculate small diameter piles bearing capacity in the soil of Londrina City, Paraná State

    Directory of Open Access Journals (Sweden)

    Miriam Gonçalves Miguel

    2005-07-01

    Full Text Available A cidade de Londrina, Estado do Paraná, possui um perfil geotécnicoconstituído de uma camada superficial de solo argilo-siltoso, poroso, laterítico e muitas vezes colapsível, que se estende até a profundidade máxima de 12 metros. As estacas utilizadas em obras de pequeno a médio porte se encontram totalmente embutidas nesta camada, sofrendo a influência de seu comportamento laterítico e colapsível. Os métodos clássicos brasileiros de estimativa de capacidade de carga de estacas tornam-se conservadores, frente aos resultados reais, quando aplicados em solos lateríticos e, contra a segurança, quando aplicados em solos colapsíveis, isto é, na condição crítica ao colapso. Este trabalho avalia os coeficientes de ajuste das resistências de ponta e ao atrito lateral para esses métodos, no caso de estacas apiloadas, sendo estes coeficientes obtidos pela retro-análise de resultados de provas de carga estática à compressão, realizadas no Campo Experimental de Engenharia Geotécnica da Universidade Estadual de Londrina.The city of Londrina, Paraná, has a typical geotechnical profile defined by a superficial layer of porous silty clay with maximum depth of about 12 meters, that shows lateritic characteristics, andmany times, collapsibility. Casts in place piles are often used for small buildings in the region and are fully embedded in this soil layer. Therefore, this type of foundation is subjected to the lateritic and occasionally collapsible influence of soil. Brazilian pile bearing capacity methods may yield conservative results when applied to tropical soils, as far as the lateritic origin in concerned. On the other hand, it can be unsafe if collapsibility prevails. This paper evaluates coefficients to adjust both point and lateral resistance of cast in place small diameter piles in the situation described. The work was carried out at the Londrina State University Geotechnical Experimental Site, and back analysis from static

  6. 考虑损伤累积及杆件失稳效应的网壳结构极限承载力分析%ANALYSIS ON ULTIMATE BEARING CAPACITY OF RETICULATED SHELL CONSIDERING CUMULATIVE DAMAGE AND INSTABILITY OF MEMBER

    Institute of Scientific and Technical Information of China (English)

    丁阳; 葛金刚; 李忠献

    2012-01-01

    Elastic-plastic constitutive model of circular steel tube,which is the stressed members of reticulated shell,is derived from mixed hardening considering cumulative damage.The discrimination criteria of instability and mechanical model after instability are introduced.VUMAT-DMB,the user material subroutine of ABAQUS suitable for 3D beam-column element,is compiled to apply cumulative damage model and instability of member in ABAQUS.The performance characteristics of the circular steel tube cantilever are compared with the results measured in the field to verify the theoretical analysis.The comparison indicates that VUMAT-DMB is accurate in evaluating the mechanical behavior of structure or members.The analysis results about a reticulated shell indicate that the cumulative damage has little effect on ultimate bearing capacity of structure,which decreased significantly when considering instability of member.%为准确分析地震作用下网壳结构的极限承载力,推导了适用于网壳结构常用杆件圆钢管的考虑损伤累积的混合强化本构模型;引入了杆件失稳判别条件和杆件失稳后的力学模型;编写了考虑损伤累积和杆件失稳效应的基于有限元软件ABAQUS空间梁单元的材料子程序VUMAT-DMB。通过与理论计算结果和已有试验结果进行比较,验证了所编程序的正确性和准确性。算例分析表明:考虑损伤累积对网壳结构极限承载力影响不大,杆件失稳效应将明显降低网壳结构极限承载力。

  7. Centrifugally decoupling touchdown bearings

    Science.gov (United States)

    Post, Richard F

    2014-06-24

    Centrifugally decoupling mechanical bearing systems provide thin tensioned metallic ribbons contained in a support structure. This assembly rotates around a stationary shaft being centered at low speeds by the action of the metal ribbons. Tension springs are connected on one end to the ribbons and on the other end to the support structure. The ribbons pass through slots in the inner ring of the support structure. The spring preloading thus insures contact (or near-contact) between the ribbons and the shaft at rotation speeds below the transition speed. Above this speed, however, the centrifugal force on the ribbons produces a tensile force on them that exceeds the spring tensile force so that the ribbons curve outward, effectively decoupling them from mechanical contact with the shaft. They still remain, however, in position to act as a touchdown bearing in case of abnormally high transverse accelerations.

  8. Government Risk-Bearing

    CERN Document Server

    1993-01-01

    The u.s. government bulks large in the nation's financial markets. The huge volume of government-issued and -sponsored debt affects the pricing and volume ofprivate debt and, consequently, resource allocation between competing alternatives. What is often not fully appreciated is the substantial influence the federal government wields overresource allocation through its provisionofcreditandrisk-bearing services to the private economy. Because peopleand firms generally seekto avoid risk, atsomeprice they are willing to pay another party to assume the risk they would otherwise face. Insurance companies are a class of private-sector firms one commonly thinks of as providing these services. As the federal government has expanded its presence in the U.S. economy during this century, it has increasingly developed programs aimed at bearing risks that the private sector either would not take on at any price, or would take on but atapricethoughtto besogreatthatmostpotentialbeneficiarieswouldnotpurchase the coverage. To...

  9. Leakage-free journal bearings

    Science.gov (United States)

    Pinkus, O.; Etsion, I.

    1976-01-01

    A new concept of a journal bearing is developed which prevents side leakage of the lubricant, thus eliminating the need for sealing and collecting this leakage. The cooling of the bearing is accomplished by the prevailing circumferential flow. An analysis is performed and solutions are given for the bearing geometries and inlet pressures required to achieve the above purpose.

  10. Study on the seismic performance of a double spherical seismic isolation bearing

    Institute of Scientific and Technical Information of China (English)

    Peng Tianbo; Li Jianzhong; Xu Yan; Fan Lichu

    2008-01-01

    In this paper,the configuration and working mechanism of the recently developed double spherical seismic isolation (DSSI) bearing are introduced in detail.Then,vertical displacement of the DSSI bearing due to sliding on a spherical surface is analyzed.The results from seismic performance testing of the bearing are given,and a numerical analysis of a four span continuous girder bridge is performed.The numerical analysis compares the influence of three different bearing arrangement schemes on the structural seismic response,and the results show that the DSSI bearing is effective in increasing the vertical load bearing capacity,reducing the vertical displacement,and controlling the energy dissipation capacity within a certain range.

  11. Bearing Behaviors of Stiffened Deep Cement Mixed Pile

    Institute of Scientific and Technical Information of China (English)

    WU Mai; ZHAO Xin

    2006-01-01

    A series of investigations were conducted to study the bearing capacity and load transfer mechanism of stiffened deep cement mixed (SDCM) pile.Laboratory tests including six specimens were conducted to investigate the frictional resistance between the concrete core and the cementsoil.Two model piles and twenty-four full-scale piles were tested to examine the bearing behavior of single pile.Laboratory and model tests results indicate that the cohesive strength is large enough to ensure the interaction between core pile and the outer cement-soil.The full-scale test results show that the SDCM piles exhibit similar bearing behavior to bored and cast-in-place concrete piles.In general, with the rational composite structure the SDCM piles can transmit the applied load effectively, and due to the addition of the stiffer core, the SDCM piles possess high bearing capacity.Based on the findings of these experimental investigations and theoretical analysis, a practical design method is developed to predict the vertical bearing capacity of SDCM pile.

  12. The Effect of Computerized Testing on Sun Bear Behavior and Enrichment Preferences

    OpenAIRE

    Perdue, Bonnie M.

    2016-01-01

    The field of comparative cognition investigates species’ differences and similarities in cognitive abilities, and sheds light on the evolutionary origins of such capacities. Cognitive testing has been carried out in a variety of species; however, there are some taxa that are underrepresented in this field. The current work follows on a recent increase in cognitive research in the order Carnivora with a specific focus on sun bears. Sun bears are the smallest existing bear species and live in t...

  13. Numerical analysis of bump foil bearings without nominal radial clearance

    Institute of Scientific and Technical Information of China (English)

    LIU Zhan-sheng; XU Huai-jin; ZHANG Guang-hui

    2008-01-01

    Bump foil bearings without nominal radial clearance were analyzed. An air film thickness model and a bearing theoretical analytical model were developed accounting for air compressibility and foil deformation. To analyze hydrodynamic characteristics of bump foil beatings with different operating eccentricities, the air film thickness equation and Reynolds equation were coupled through pressure and solved by Newton-Raphson Method(NRM) and Finite Difference Method (FDM). The characteristics of an bump foil bearing model were dis-cussed including load carrying capacity, film thickness and pressure distributions. The results of simulation show that bump foil beating without nominal radial clearance can provide better stability and greater load capaci-ty. This numerical analytical method also reveals a good convergence in numerical calculation.

  14. Anti-backlash gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2009-01-01

    A gear bearing having a first gear and a second gear, each having a plurality of teeth. Each gear operates on two non-parallel surfaces of the opposing gear teeth to perform both gear and bearing functions simultaneously. The gears are moving at substantially the same speed at their contact points. The gears may be roller gear bearings or phase-shifted gear bearings, and may be arranged in a planet/sun system or used as a transmission. One preferred embodiment discloses and describes an anti-backlash feature to counter ''dead zones'' in the gear bearing movement.

  15. Simulation of the fluid structure interaction for an aerostatic bearing and a flexible substrate

    NARCIS (Netherlands)

    Olieslagers, R.; Wild, M. de; Melick, S. van; Knaapen, R.

    2014-01-01

    The fluid structure interaction for an aerostatic bearing and a substrate is solved numerically by a semi-analytical model, programmed in the software package MATLAB. This semi-analytical model uses a fluidic network of resistances and capacities to solve the pressure field in the bearing channel. T

  16. Damping Bearings In High-Speed Turbomachines

    Science.gov (United States)

    Von Pragenau, George L.

    1994-01-01

    Paper presents comparison of damping bearings with traditional ball, roller, and hydrostatic bearings in high-speed cryogenic turbopumps. Concept of damping bearings described in "Damping Seals and Bearings for a Turbomachine" (MFS-28345).

  17. Aerospace applications of magnetic bearings

    Science.gov (United States)

    Downer, James; Goldie, James; Gondhalekar, Vijay; Hockney, Richard

    1994-01-01

    Magnetic bearings have traditionally been considered for use in aerospace applications only where performance advantages have been the primary, if not only, consideration. Conventional wisdom has been that magnetic bearings have certain performance advantages which must be traded off against increased weight, volume, electric power consumption, and system complexity. These perceptions have hampered the use of magnetic bearings in many aerospace applications because weight, volume, and power are almost always primary considerations. This paper will review progress on several active aerospace magnetic bearings programs at SatCon Technology Corporation. The magnetic bearing programs at SatCon cover a broad spectrum of applications including: a magnetically-suspended spacecraft integrated power and attitude control system (IPACS), a magnetically-suspended momentum wheel, magnetic bearings for the gas generator rotor of a turboshaft engine, a vibration-attenuating magnetic bearing system for an airborne telescope, and magnetic bearings for the compressor of a space-rated heat pump system. The emphasis of these programs is to develop magnetic bearing technologies to the point where magnetic bearings can be truly useful, reliable, and well tested components for the aerospace community.

  18. Nanoprecipitation in bearing steels

    Energy Technology Data Exchange (ETDEWEB)

    Barrow, A.T.W. [SKF University Technology Centre, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom); Rivera-Diaz-del-Castillo, P.E.J., E-mail: pejr2@cam.ac.uk [SKF University Technology Centre, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom)

    2011-11-15

    {theta}-phase is the main hardening species in bearing steels and appears in both martensitically and bainitically hardened microstructures. This work presents a survey of the microstrucural features accompanying nanoprecipitation in bearing steels. Nanoprecipitate structures formed in 1C-1.5Cr wt.% with additions of Cr, Mn, Mo, Si and Ni are studied. The work is combined with thermodynamic calculations and neural networks to predict the expected matrix composition, and whether this will transform martensitically or bainitically. Martensite tetragonality, composition and the amount of retained austenite are related to hardness and the type of nanoprecipitate structures in martensitic grades. The {theta}-phase volume fraction, the duration of the bainite to austenite transformation and the amount of retained austenite are related to hardness and a detailed quantitative description of the precipitate nanostructures. Such description includes compositional studies using energy-dispersive spectroscopy, which shows that nanoprecipitate formation takes place under paraequilibrium. Special attention is devoted to a novel two-step bainite tempering process which shows maximum hardness; we prove that this is the most effective process for incorporating solute into the precipitates, which are finer than those resulting from one-step banitic transformation processes.

  19. Computational design of rolling bearings

    CERN Document Server

    Nguyen-Schäfer, Hung

    2016-01-01

    This book comprehensively presents the computational design of rolling bearings dealing with many interdisciplinary difficult working fields. They encompass elastohydrodynamics (EHD), Hertzian contact theory, oil-film thickness in elastohydrodynamic lubrication (EHL), bearing dynamics, tribology of surface textures, fatigue failure mechanisms, fatigue lifetimes of rolling bearings and lubricating greases, Weibull distribution, rotor balancing, and airborne noises (NVH) in the rolling bearings. Furthermore, the readers are provided with hands-on essential formulas based on the up-to-date DIN ISO norms and helpful examples for computational design of rolling bearings. The topics are intended for undergraduate and graduate students in mechanical and material engineering, research scientists, and practicing engineers who want to understand the interactions between these working fields and to know how to design the rolling bearings for automotive industry and many other industries.

  20. Application of a non-coaxial constitutive model in the FEM analysis of the suction buckets bearing capacity%非共轴本构模型在吸力桶地基承载力有限元分析中应用

    Institute of Scientific and Technical Information of China (English)

    罗强; 栾茂田; 杨蕴明

    2012-01-01

    When the direction of soil principal stress rotates during the shearing process, there is a non-coaxial phenomenon between the direction of principal strain rate and the direction of principal stress, bill the conventional elastoplastic constitutive mode! could not take this phenomenon into consideration. In order to reflect the non-coaxial phenomenon, a non-coaxial plastic strain rate term is added on the tangential direction of conventional constitutive model's yield surface. Based on the material subroutine UMAT of FEM software ABAQUS, the non-coaxial model is numerically implemented into the application of FEM analysis using automatic substepping scheme with explicit integral algorithm. Firstly, a numerical simulation of sand's simple shear test is carried out to predict the relationship between the direction of principal stress and the direction of principal strain rate, and the conclusion is in good agreement with the experimental results. Secondly, the problem of interaction between suction bucket and sand foundation is taken into the elasto-plastic FEM a-nalysis, the rotation law of the direction of principal stress and the variation trend of resistance of the bucket' s top, tip and side walls are researched. And then, the influence of the non-coaxial phenomenon on the numerical result of the foundation' s bearing capacity is checked. It can be concluded that the non-coaxial model used in this paper has a good predictive ability of the non-coaxial phenomenon.%土体在剪切变形过程中产生主应力方向的旋转时,主应变率方向与主应力方向之间存在若非共轴现象,然而,传统的弹塑性本构模型并不能考虑该现象的影响.通过在传统本构模型屈服面的切线方向增加一项非共轴塑性应变率,即可实现对非共轴现象的反映.利用有限元软件ABAQUS的材料子程序接口UMAT,通过显式积分算法和自动分步方法实现了非共轴模型在有限元分析中的应用.首先,对砂土的

  1. Study on Bearing Capacity of Circular Tubular T-Joints with Collar-Plate Reinforcement Loaded by In-Plane Bending Load%平面内弯矩作用下环口板加强T型圆钢管节点的承载力分析

    Institute of Scientific and Technical Information of China (English)

    陈德胜; 杨冬平; 蔡艳青; 龙凤乐; 牛更奇; 邵永波

    2014-01-01

    环口板加固管节点是一种比较新颖的加固方法,施工方便快捷而且加固效果显著。运用有限元方法对平面内弯矩作用下的环口板加固 T 型圆钢管节点的极限承载力进行了研究。对环口板加固 T 型圆钢管节点的面内弯曲承载力进行了参数分析,参数包括支管直径与主管直径比β,主管直径与2倍主管壁厚的比γ,环口板厚度与主管管壁厚之比τc 和环口板长度与支管直径之比 lc/d1等计算。结果表明,采用适当尺寸的环口板加固后的 T 型管节点的承载力相对于未加固 T 型管节点的承载力得到显著提高。改变环口板的厚度相对于改变环口板的长度对静力强度的提高更有效。最后,在参数分析的基础上提出了环口板加强型 T 型圆钢管节点在平面内弯矩作用下的承载力计算公式。%Collar plate reinforcement is a new method for reinforcing tubular joints, and it is of fast fabrication and effective. Finite element method is used to investigate the static strength of collar plate reinforced circular hollow section (CHS) T-joints subjected to in-plane bending load. A study is conducted to analyze the effect of geometrical parameters, i.e. brace-to-chord diameter ratio β, collar-plate to chord wall thickness ratio τc, and collar-plate length to brace diameter ratio lc/d1, on the static strength of tubular T-joints. It is found that significant strength enhancement can be achieved for a collar plate reinforced tubular joint through suitable size design comparing with the un-reinforced one. Compared to the length of the collar plate, the thicknesses of the collar plate is more effective for improving the static strength of the T-joints. Finally, a parametric equation for predicting the load bearing capacity of circular tubular T-joints with collar plate reinforcement subjected to in-plane bending load is presented.

  2. Grease lubrication in rolling bearings

    CERN Document Server

    Lugt, Piet M

    2012-01-01

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

  3. Cyanines Bearing Quaternary Azaaromatic Moieties

    OpenAIRE

    Sbliwa, Wanda; Matusiak, Grazyna; Bachowska, Barbara

    2006-01-01

    Selected cyanines bearing quaternary azaaromatic moieties are presented, showing their monomers, dimers and polymers, as well as their possible applications. Cyanines having NLO properties are also briefly described.

  4. Hydrostatic and hybrid bearing design

    CERN Document Server

    Rowe, W B

    1983-01-01

    Hydrostatic and Hybrid Bearing Design is a 15-chapter book that focuses on the bearing design and testing. This book first describes the application of hydrostatic bearings, as well as the device pressure, flow, force, power, and temperature. Subsequent chapters discuss the load and flow rate of thrust pads; circuit design, flow control, load, and stiffness; and the basis of the design procedures and selection of tolerances. The specific types of bearings, their design, dynamics, and experimental methods and testing are also shown. This book will be very valuable to students of engineering des

  5. Modeling and Development of RMD Configuration Magnetic Bearing

    Directory of Open Access Journals (Sweden)

    K.P. Lijesh

    2015-06-01

    Full Text Available The low load carrying capacity of Passive Magnetic Bearings (PMBs has restricted their use in many industrial applications. The Rotation Magnetized Direction (RMD configuration has emerged as a strong and viable method that is able to substantially enhance the load carrying capacity of passive magnetic bearings. It consists of both radially and axially polarized passive magnets. But the physical realization of a radially polarized magnet is difficult to achieve. In the present work, a RMD structure consisting of aluminum ring and cubical shaped magnets is proposed by developing the radially polarized magnets required for RMD structure. A theoretical model is derived by simulating the cuboid magnets in form of sector magnets by developing equivalent surface area. An experimental setup was designed and developed to conduct experimental verification. The theoretical model is validated by conducting experiments on RMD configuration magnetic bearing and axially magnetized full ring bearing. The comparison of the load carrying capacity by different configuration is performed and results are presented.

  6. Sensitivity analysis of size effect on the performance of hydrostatic bearing

    Directory of Open Access Journals (Sweden)

    Dongju Chen

    2016-01-01

    Full Text Available For size effect on solid-liquid interface of hydrostatic bearing oil film gap flow in two-dimension, fluid dynamic method is applied to investigate the influence of size effect on bearing capacity, dynamic stiffness and other performances. With the consideration of size effect, Reynolds equation is modified by adopting velocity slip boundary condition into Reynolds equation. The sensitivity factors are used to make a quantitative and qualitative analysis. Numerical simulation results show that size effect will affect bearing performances to a certain degree and the effect curve of size effect on bearing performances are given. The four maximum oil film pressures reduce with the increase of slip length. The maximum sensitivity of bearing capacity is 81.94%.

  7. Studying fluid squeeze characteristics for aerostatic journal bearing

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Rahman, Gamal M. [Department of Mathematics, Faculty of Science, Benha University, Benha 13518 (Egypt)], E-mail: gamalm60@yahoo.com

    2008-07-01

    The Reynolds equation for studying fluid squeeze of aerostatic journal bearing is solved numerically by considering the quasi-steady behavior of the air film. The radial displacement can influence the air film thickness modifying the pressure distribution in the journal-bearing gap. Also, the variations in the seal characteristics with eccentricity, time, squeeze number, length-to-diameter and supply pressure are presented. The numerical results for the squeeze load-carrying capacity are given in a non-dimensional for000.

  8. Permanent-Magnet Meissner Bearing

    Science.gov (United States)

    Robertson, Glen A.

    1994-01-01

    Permanent-magnet meissner bearing features inherently stable, self-centering conical configuration. Bearing made stiffer or less stiff by selection of magnets, springs, and spring adjustments. Cylindrical permanent magnets with axial magnetization stacked coaxially on rotor with alternating polarity. Typically, rare-earth magnets used. Magnets machined and fitted together to form conical outer surface.

  9. High-Performance Ball Bearing

    Science.gov (United States)

    Bursey, Roger W., Jr.; Haluck, David A.; Olinger, John B.; Owen, Samuel S.; Poole, William E.

    1995-01-01

    High-performance bearing features strong, lightweight, self-lubricating cage with self-lubricating liners in ball apertures. Designed to operate at high speed (tens of thousands of revolutions per minute) in cryogenic environment like liquid-oxygen or liquid-hydrogen turbopump. Includes inner race, outer race, and cage keeping bearing balls equally spaced.

  10. Superconducting bearings for flywheel applications

    DEFF Research Database (Denmark)

    Abrahamsen, A.B.

    2001-01-01

    A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found onthe applications of superconducting bearings...

  11. What about the Javan Bear?

    NARCIS (Netherlands)

    Jentink, F.A.

    1898-01-01

    The other day I read in a dutch popular periodical a paper dealing with the different species of Bears and their geographical distribution. To my great surprise the Malayan Bear was mentioned from Java: the locality Java being quite new to me I wrote to the author of that paper and asked him some in

  12. Geophagy by yellowstone grizzly bears

    Science.gov (United States)

    Mattson, D.J.; Green, G.I.; Swalley, R.

    1999-01-01

    We documented 12 sites in the Yellowstone ecosystem where grizzly bears (Ursus arctos horribilis) had purposefully consumed soil (an activity known as geophagy). We also documented soil in numerous grizzly bear feces. Geophagy primarily occurred at sites barren of vegetation where surficial geology had been modified by geothermal activity. There was no evidence of ungulate use at most sites. Purposeful consumption of soil by bears peaked first from March to May and again from August to October, synchronous with peaks in consumption of ungulate meat and mushrooms. Geophageous soils were distinguished from ungulate mineral licks and soils in general by exceptionally high concentrations of potassium (K) and high concentrations of magnesium (Mg) and sulphur (S). Our results do not support the hypotheses that bears were consuming soil to detoxify secondary compounds in grazed foliage, as postulated for primates, or to supplement dietary sodium, as known for ungulates. Our results suggest that grizzly bears could have been consuming soil as an anti-diarrheal.

  13. Body and diet composition of sympatric black and grizzly bears in the Greater Yellowstone Ecosystem

    Science.gov (United States)

    Schwartz, Charles C.; Fortin, Jennifer K.; Teisberg, Justin E.; Haroldson, Mark A.; Servheen, Christopher; Robbins, Charles T.; van Manen, Frank T.

    2013-01-01

    The Greater Yellowstone Ecosystem (GYE) has experienced changes in the distribution and availability of grizzly bear (Ursus arctos) food resources in recent decades. The decline of ungulates, fish, and whitebark pine seeds (Pinus albicaulis) has prompted questions regarding their ability to adapt. We examined body composition and diet of grizzly bears using bioelectrical impedance and stable isotopes to determine if 1) we can detect a change in diet quality associated with the decline in either ungulates or whitebark pine, and 2) the combined decline in ungulates, fish, and pine seeds resulted in a change in grizzly bear carrying capacity in the GYE. We contrasted body fat and mass in grizzly bears with a potential competitor, the American black bear (Ursus americanus), to address these questions. Grizzly bears assimilated more meat into their diet and were in better body condition than black bears throughout the study period, indicating the decline in ungulate resources did not affect grizzly bears more than black bears. We also found no difference in autumn fat levels in grizzly bears in years of good or poor pine seed production, and stable isotope analyses revealed this was primarily a function of switching to meat resources during poor seed-producing years. This dietary plasticity was consistent over the course of our study. We did not detect an overall downward trend in either body mass or the fraction of meat assimilated into the diet by grizzly bears over the past decade, but we did detect a downward trend in percent body fat in adult female grizzly bears after 2006. Whether this decline is an artifact of small sample size or due to the population reaching the ecological carrying capacity of the Yellowstone ecosystem warrants further investigation.

  14. 模拟失重对大鼠承重骨骨髓基质细胞数量及体外成骨能力的影响%Effects of simulated weightlessness on bone marrow stromal cell count and osteogentic capacity of weight bearing bone in rats

    Institute of Scientific and Technical Information of China (English)

    付崇建; 郁冰冰; 杨连甲; 曹新生; 张立藩

    2007-01-01

    of simulated weightlessness on bone marrow stromal cell count and osteogentic capacity of weight bearing bone in rats so as to reveal the mechanism of bone loss.DESIGN : Randomized pairing and controlled study.SETTING: College of Aerospace Medicine and Department of Pathology of Stomatology College, the Fourth Military Medical University of Chinese PLA.MATERIALS: A total of 20 adult healthy male SD rats were selected in this study. At the beginning of experiment, rats based on their body mass were randomly divided into control group and suspension group with 10 in each group. Alkaline phosphatase kit was provided by Beijing Zhongsheng Bioengineering High-technological Company.METHODS: The experiment was carried out in the Department of Pathology, Collage of Stomatology, the Fourth Military Medical University of Chinese PLA from November 1999 to July 2000. Rats were randomly divided into tail suspension group and control group with 10 in each group. Rats in the tail suspension group were given tail suspension for 28 days. Their heads maintained 30° low position, and their hindlimbs freely suspended and were not given weight loading. While, rats in the control group were fed normally. At the end of experiment, bone marrow stromal cells were obtained from femur for primary and transferring cultures.MAIN OUTCOME MEASURES: Cell counting and methylthianolyldiphenyl-tetrazolium bromide (MTT) assay were used to draw growth curve of cells in primary and transferring cultures and to measure activity of alkaline phosphatase and forming quantity of mineralized nodules in vitro.RESULTS : ① Activity of alkaline phosphatase: Activity of alkaline phosphatase of cells in the primary and transferring cultures in the suspension group was lower than that in the control group, and there was significant difference between them (P<0.05). ② Forming quantity of mineralized nodules: Forming quantity of mineralized nodules in the suspension group was less than that in the control group

  15. Discontinuous symplectic capacities

    NARCIS (Netherlands)

    Zehmisch, K.; Ziltener, F.J.

    2014-01-01

    We show that the spherical capacity is discontinuous on a smooth family of ellipsoidal shells. Moreover, we prove that the shell capacity is discontinuous on a family of open sets with smooth connected boundaries.

  16. Eastern slopes grizzly bear project

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-01-01

    The cumulative effects of human activities on the grizzly bears in the central Canadian Rockies are not well known. As a result, a project was initiated in 1994 to address the urgent requirement for accurate scientific information on the habitat and populations of grizzly bears in the area of the Banff National Park and Kananaskis Country. This area is probably the most heavily used and developed area where the grizzly still survives. The information gathered throughout the course of this study will be used to better protect and manage the bears and other sensitive carnivores in the region. Using telemetry, researchers are monitoring 25 grizzly bears which were radio-collared in a 22,000 square-kilometer area in the upper Bow Valley drainage of the eastern Alberta slopes. The researchers involved in the project are working with representatives from Husky Oil and Talisman Energy on the sound development of the Moose Mountain oil and gas field without adversely affecting the grizzly bear population. Information collected over seven years indicated that the grizzly bears have few and infrequent offspring. Using the information gathered so far, the location of the Moose Mountain to Jumping Pound pipeline was carefully selected, since the bears recover very slowly from high mortality, and also considering that the food and cover had already been compromised by the high number of roads, trails and other human activities in the area. The status of the population and habitat of the grizzly bear will be assessed upon the conclusion of the field research phase in 2001. Models will be updated using the data obtained during eight years and will assist in the understanding of complex variables that affect grizzly bears.

  17. EFFECT OF BEARING MACROGEOMETRY ON BEARING PERFORMANCE IN ELASTOHYDRODYNAMIC LUBRICATION

    Directory of Open Access Journals (Sweden)

    Emin GÜLLÜ

    2000-01-01

    Full Text Available During manufacturing, ideal dimension and mutual positioning of machine elements proposed in project desing can be achieved only within certain range of tolerances. These tolerances, being classified in two groups, related to micro and macro geometry of machine elements, don't have to effect the functioning of these elements. So, as for all machine elements, investigation of the effects of macro and micro tolerances for journal bearings is important. In this study, we have investigated the effect of macro geometric irregularities of journal bearings on performance characteristics. In this regard, we have studied the change of bearing performance in respect to deviation from ideal circle for an elliptic shaft with small ovality rolling in circular journal bearing.

  18. Bears, Big and Little. Young Discovery Library Series.

    Science.gov (United States)

    Pfeffer, Pierre

    This book is written for children 5 through 10. Part of a series designed to develop their curiosity, fascinate them and educate them, this volume describes: (1) the eight species of bears, including black bear, brown bear, grizzly bear, spectacled bear, sun bear, sloth bear, polar bear, and giant panda; (2) geographical habitats of bears; (3)…

  19. CDMA systems capacity engineering

    CERN Document Server

    Kim, Kiseon

    2004-01-01

    This new hands-on resource tackles capacity planning and engineering issues that are crucial to optimizing wireless communication systems performance. Going beyond the system physical level and investigating CDMA system capacity at the service level, this volume is the single-source for engineering and analyzing systems capacity and resources.

  20. Dynamic force response of spherical hydrostatic journal bearing for cryogenic applications

    Science.gov (United States)

    Sanandres, Luis

    1994-01-01

    Hydrostatic Journal Bearings (HJB's) are reliable and resilient fluid film rotor support elements ideal to replace roller bearings in cryogenic turbomachinery. HJB' will be used for primary space-power applications due to their long lifetime, low friction and wear, large load capacity, large direct stiffness, and damping force coefficients. An analysis for the performance characteristics of turbulent flow, orifice compensated, spherical hydrostatic journal bearings (HJB's) is presented. Spherical bearings allow tolerance for shaft misalignment without force performance degradation and have also the ability to support axial loads. The spherical HJB combines these advantages to provide a bearing design which could be used efficiently on high performance turbomachinery. The motion of a barotropic liquid on the thin film bearing lands is described by bulk-flow mass and momentum equations. These equations are solved numerically using an efficient CFD method. Numerical predictions of load capacity and force coefficients for a 6 recess, spherical HJB in a LO2 environment are presented. Fluid film axial forces and force coefficients of a magnitude about 20% of the radial load capacity are predicted for the case analyzed. Fluid inertia effects, advective and centrifugal, are found to affect greatly the static and dynamic force performance of the bearing studied.

  1. Active Displacement Control of Active Magnetic Bearing System

    Directory of Open Access Journals (Sweden)

    Kertész Milan

    2014-12-01

    Full Text Available The worldwide energy production nowadays is over 3400 GW while storage systems have a capacity of only 90 GW [1]. There is a good solution for additional storage capacity in flywheel energy storage systems (FES. The main advantage of FES is its relatively high efficiency especially with using the active magnetic bearing system. Therefore there exist good reasons for appropriate simulations and for creating a suitable magneto-structural control system. The magnetic bearing, including actuation, is simulated in the ANSYS parametric design language (APDL. APDL is used to create the loops of transient simulations where boundary conditions (BC are updated based upon a “gap sensor” which controls the nodal position values of the centroid of the shaft and the current density inputs onto the copper windings.

  2. Active Displacement Control of Active Magnetic Bearing System

    Science.gov (United States)

    Kertész, Milan; Kozakovič, Radko; Magdolen, Luboš; Masaryk, Michal

    2014-12-01

    The worldwide energy production nowadays is over 3400 GW while storage systems have a capacity of only 90 GW [1]. There is a good solution for additional storage capacity in flywheel energy storage systems (FES). The main advantage of FES is its relatively high efficiency especially with using the active magnetic bearing system. Therefore there exist good reasons for appropriate simulations and for creating a suitable magneto-structural control system. The magnetic bearing, including actuation, is simulated in the ANSYS parametric design language (APDL). APDL is used to create the loops of transient simulations where boundary conditions (BC) are updated based upon a "gap sensor" which controls the nodal position values of the centroid of the shaft and the current density inputs onto the copper windings.

  3. Myrmecophagy by Yellowstone grizzly bears

    Science.gov (United States)

    Mattson, D.J.

    2001-01-01

    I used data collected during a study of radio-marked grizzly bears (Ursus arctos horribilis) in the Yellowstone region from 1977 to 1992 to investigate myrmecophagy by this population. Although generally not an important source of energy for the bears (averaging 8 mm long) nested in logs over small ants (6 mm long) nested under stones. Optimal conditions for consumption of ants occurred on the warmest sites with ample substrate suitable for ant nests. For ants in mounds, this occurred at low elevations at non-forested sites. For ants in logs, this occurred at low elevations or on southerly aspects where there was abundant, large-diameter, well-decomposed woody debris under an open forest canopy. Grizzly bears selected moderately decomposed logs 4a??5 dm in diameter at midpoint. Ants will likely become a more important food for Yellowstone's grizzly bears as currently important foods decline, owing to disease and warming of the regional climate.

  4. Segmented Hybrid Gasostatic Bearing Optimization

    Directory of Open Access Journals (Sweden)

    Prodan Nikolay Vasilevich

    2014-07-01

    Full Text Available The purpose of research-development of methods of numerical optimization rotatable support pads gasostatic hybrid bearing. In the world‘s aerospace engineering the gas-dynamic bearings are currently most common. They are characterized by the supporting layer of different designs, which ensures the workability of the rotors during starts and stops. The main problem of this bearing type, apart from the construction complexity is the wear of this supporting layer. Gas-static bearing has no such defect, since there is no physical contact between solid surfaces. This study presents the results of the hybrid bearing’s calculation, combining both technologies. The slotted nozzle of non-conventional shape that mirrors the solution of Reynolds equation’s isoline is studied. The dependences of the main parameters on the speed of the shaft’s rotation are discussed. The aerodynamic resistance of pads for different regimes of operation is investigated.

  5. Gas bearing operates in vacuum

    Science.gov (United States)

    Perkins, G. S.

    1975-01-01

    Bearing has restrictions to reduce air leaks and is connected to external pumpout facility which removes exhausted air. Token amount of air which is lost to vacuum is easily removed by conventional vacuum pump.

  6. Mixed-mu superconducting bearings

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL); Mulcahy, Thomas M. (Western Springs, IL)

    1998-01-01

    A mixed-mu superconducting bearing including a ferrite structure disposed for rotation adjacent a stationary superconductor material structure and a stationary permanent magnet structure. The ferrite structure is levitated by said stationary permanent magnet structure.

  7. Capacity Statement for Railways

    DEFF Research Database (Denmark)

    Landex, Alex

    2007-01-01

    The subject “Railway capacity” is a combination of the capacity consumption and how the capacity is utilized. The capacity utilization of railways can be divided into 4 core elements: The number of trains; the average speed; the heterogeneity of the operation; and the stability. This article...... describes how the capacity consumption for railways can be worked out and analytical measurements of how the capacity is utilized. Furthermore, the article describes how it is possible to state and visualize railway capacity. Having unused railway capacity is not always equal to be able to operate more...... trains. This is due to network effects in the railway system and due to the fact that more trains results in lower punctuality....

  8. Nonlinear Control of Magnetic Bearings

    Institute of Scientific and Technical Information of China (English)

    Khac Duc Do; Dang Hoe Nguyen; Thanh Binh Nguyen

    2010-01-01

    In this paper, recent results controling nonlinear systems with output tracking error constraints are applied to the design of new tracking controllers for magnetic bearings. The proposed controllers can force the rotor to track a bounded and sufficiently smooth refer-ence trajectory asymptotically and guarantee non-contactedness be-tween the rotor and the stator of the magnetic bearings. Simulation results are included to illustrate the effectiveness of the proposed con-trollers.

  9. 77 FR 70423 - Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC...

    Science.gov (United States)

    2012-11-26

    ... Energy Regulatory Commission Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC; Notice of Application for Partial Transfer of Licenses, and Soliciting Comments and Motions To Intervene On October 25, 2012, Black Bear Hydro Partners, LLC, sole licensee (transferor)...

  10. Evaluation of railway capacity

    DEFF Research Database (Denmark)

    Landex, Alex; Kaas, Anders H.; Schittenhelm, Bernd

    2006-01-01

    This paper describes the relatively new UIC 406 method for calculating capacity consumption on railway lines. The UIC 406 method is an easy and effective way of calculating the capacity consumption, but it is possible to expound the UIC 406 method in different ways which can lead to different...... of a railway network. Some of the aspects which have to be paid attention to making annual capacity statements are presented too....

  11. Capacity Building in Vietnam

    OpenAIRE

    Adam McCarty

    2001-01-01

    This report is the outcome of a study commissioned to examine the capacity building needs in Vietnam, and is a supplementary document to the Asian Development Bank's Country Operational Strategy for Vietnam. Vietnam's needs in terms of capacity building are particularly important given that is it a transitional economy and also one with little institutional experience in dealing with the international donor community. This paper examines the international awareness of capacity building and ca...

  12. The Effect of Computerized Testing on Sun Bear Behavior and Enrichment Preferences.

    Science.gov (United States)

    Perdue, Bonnie M

    2016-09-22

    The field of comparative cognition investigates species' differences and similarities in cognitive abilities, and sheds light on the evolutionary origins of such capacities. Cognitive testing has been carried out in a variety of species; however, there are some taxa that are underrepresented in this field. The current work follows on a recent increase in cognitive research in the order Carnivora with a specific focus on sun bears. Sun bears are the smallest existing bear species and live in tropical regions of Southeast Asia. They have an omnivorous diet and use their tongues to forage for insects and sap. Little is known about sun bear cognition, although much like other bear species, anecdotes suggest a high level of intelligence. The current work explored training sun bears to use a touchscreen computer. This effort allows for insight into cognitive abilities as well as providing a complex source of enrichment for the bears. The bears use their tongues to respond to a touchscreen computer, and the effects on stereotypic behaviors on exhibit and preference for this over other forms of enrichment were examined. Overall, bears performed well on the task and showed a preference for the computer.

  13. The Effect of Computerized Testing on Sun Bear Behavior and Enrichment Preferences

    Directory of Open Access Journals (Sweden)

    Bonnie M. Perdue

    2016-09-01

    Full Text Available The field of comparative cognition investigates species’ differences and similarities in cognitive abilities, and sheds light on the evolutionary origins of such capacities. Cognitive testing has been carried out in a variety of species; however, there are some taxa that are underrepresented in this field. The current work follows on a recent increase in cognitive research in the order Carnivora with a specific focus on sun bears. Sun bears are the smallest existing bear species and live in tropical regions of Southeast Asia. They have an omnivorous diet and use their tongues to forage for insects and sap. Little is known about sun bear cognition, although much like other bear species, anecdotes suggest a high level of intelligence. The current work explored training sun bears to use a touchscreen computer. This effort allows for insight into cognitive abilities as well as providing a complex source of enrichment for the bears. The bears use their tongues to respond to a touchscreen computer, and the effects on stereotypic behaviors on exhibit and preference for this over other forms of enrichment were examined. Overall, bears performed well on the task and showed a preference for the computer.

  14. Visual attention capacity

    DEFF Research Database (Denmark)

    Habekost, Thomas; Starrfelt, Randi

    2009-01-01

    Psychophysical studies have identified two distinct limitations of visual attention capacity: processing speed and apprehension span. Using a simple test, these cognitive factors can be analyzed by Bundesen's Theory of Visual Attention (TVA). The method has strong specificity and sensitivity...... to patient testing, and review existing TVA-based patient studies organized by lesion anatomy. Lesions in three anatomical regions affect visual capacity: The parietal lobes, frontal cortex and basal ganglia, and extrastriate cortex. Visual capacity thus depends on large, bilaterally distributed anatomical...... networks that include several regions outside the visual system. The two visual capacity parameters are functionally separable, but seem to rely on largely overlapping brain areas....

  15. Flywheel energy storage using superconducting magnetic bearings

    Science.gov (United States)

    Abboud, R. G.; Uherka, K.; Hull, J.; Mulcahy, T.

    Storage of electrical energy on a utility scale is currently not practicable for most utilities, preventing the full utilization of existing base-load capacity. A potential solution to this problem is Flywheel Energy Storage (FES), made possible by technological developments in high-temperature superconducting materials. Commonwealth Research Corporation (CRC), the research arm of Commonwealth Edison Company, and Argonne National Laboratory are implementing a demonstration project to advance the state of the art in high temperature superconductor (HTS) bearing performance and the overall demonstration of efficient Flywheel Energy Storage. Currently, electricity must be used simultaneously with its generation as electrical energy storage is not available for most utilities. Existing storage methods either are dependent on special geography, are too expensive, or are too inefficient. Without energy storage, electric utilities, such as Commonwealth Edison Company, are forced to cycle base load power plants to meet load swings in hourly customer demand. Demand can change by as much as 30% over a 12-hour period and result in significant costs to utilities as power plant output is adjusted to meet these changes. HTS FES systems can reduce demand-based power plant cycling by storing unused nighttime capacity until it is needed to meet daytime demand.

  16. Superconductor bearings, flywheels and transportation

    Science.gov (United States)

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

    2012-01-01

    This paper describes the present status of high temperature superconductors (HTS) and of bulk superconducting magnet devices, their use in bearings, in flywheel energy storage systems (FESS) and linear transport magnetic levitation (Maglev) systems. We report and review the concepts of multi-seeded REBCO bulk superconductor fabrication. The multi-grain bulks increase the averaged trapped magnetic flux density up to 40% compared to single-grain assembly in large-scale applications. HTS magnetic bearings with permanent magnet (PM) excitation were studied and scaled up to maximum forces of 10 kN axially and 4.5 kN radially. We examine the technology of the high-gradient magnetic bearing concept and verify it experimentally. A large HTS bearing is tested for stabilizing a 600 kg rotor of a 5 kWh/250 kW flywheel system. The flywheel rotor tests show the requirement for additional damping. Our compact flywheel system is compared with similar HTS-FESS projects. A small-scale compact YBCO bearing with in situ Stirling cryocooler is constructed and investigated for mobile applications. Next we show a successfully developed modular linear Maglev system for magnetic train operation. Each module levitates 0.25t at 10 mm distance during one-day operation without refilling LN2. More than 30 vacuum cryostats containing multi-seeded YBCO blocks are fabricated and are tested now in Germany, China and Brazil.

  17. The Effect of Additives on The Performance of HydrostaticThrust Bearings

    Directory of Open Access Journals (Sweden)

    Muhammed Abdul Sattar

    2008-01-01

    Full Text Available The paper is concerned with, the behavior of the hydrostatic thrust bearings lubricated with liquid-solid lubricants using Einstein viscosity formula, and taking into account the centrifugal force resulting from high speed. Also studied is the effect of the bearing dimensions on the pressure, flow rate, load capacity, shear stress, power consumption and stiffness. The theoretical results show an increase in load capacity by (8.3% in the presence of solid graphite particles with concentration of (16% by weight as compared with pure oil, with increasing shear stress. . In general the performance of hydrostatic thrust bearings improve for load carrying capacity, volume flow rate, pumping power subjected to centrifugal parameter (S, recess position (r1, film thickness ratio (, particle concentration (.

  18. Magnetic bearings with zero bias

    Science.gov (United States)

    Brown, Gerald V.; Grodsinsky, Carlos M.

    1991-01-01

    A magnetic bearing operating without a bias field has supported a shaft rotating at speeds up to 12,000 rpm with the usual four power supplies and with only two. A magnetic bearing is commonly operated with a bias current equal to half of the maximum current allowable in its coils. This linearizes the relation between net force and control current and improves the force slewing rate and hence the band width. The steady bias current dissipates power, even when no force is required from the bearing. The power wasted is equal to two-thirds of the power at maximum force output. Examined here is the zero bias idea. The advantages and disadvantages are noted.

  19. Dynamic Performance Characteristics of a Curved Slider Bearing Operating with Ferrofluids

    Directory of Open Access Journals (Sweden)

    Udaya P. Singh

    2012-01-01

    Full Text Available In the present theoretical investigation, the effect of ferrofluid on the dynamic characteristics of curved slider bearings is presented using Shliomis model which accounts for the rotation of magnetic particles, their magnetic moments, and the volume concentration in the fluid. The modified Reynolds equation for the dynamic state of the bearing is obtained. The results of dynamic stiffness and damping characteristics are presented. It is observed that the effect of rotation of magnetic particles improves the stiffness and damping capacities of the bearings.

  20. Static, Dynamic, and Thermal Properties of Compressible Fluid Film Journal Bearings

    DEFF Research Database (Denmark)

    Paulsen, Bo Terp; Morosi, Stefano; Santos, Ilmar

    2011-01-01

    fluid film journal bearing, in order to identify when this type of analysis should be of concern. Load capacity, stiffness, and damping coefficients are determined by the solution of the standard Reynolds equation coupled to the energy equation. Numerical investigations show how bearing geometry......Modern turbo-machinery applications, high-speed machine tools, and laboratory equipment require ever-growing rotational speeds and high degree of precision and reliability. Gas journal bearings are often employed because they meet the demands of high-speed performance, in a clean environment...

  1. Liquid heat capacity lasers

    Science.gov (United States)

    Comaskey, Brian J.; Scheibner, Karl F.; Ault, Earl R.

    2007-05-01

    The heat capacity laser concept is extended to systems in which the heat capacity lasing media is a liquid. The laser active liquid is circulated from a reservoir (where the bulk of the media and hence waste heat resides) through a channel so configured for both optical pumping of the media for gain and for light amplification from the resulting gain.

  2. The Chevron Foil Thrust Bearing: Improved Performance Through Passive Thermal Management and Effective Lubricant Mixing

    Science.gov (United States)

    Bruckner, Robert

    2013-01-01

    An improved foil thrust bearing is described that eliminates or reduces the need for forced cooling of the bearing foils while at the same time improves the load capacity of the bearing, enhances damping, provides overload tolerance, and eliminates the high speed load capacity drop-off that plagues the current state of the art. The performance improvement demonstrated by the chevron foil thrust bearing stems from a novel trailing edge shape that splays the hot lubricant in the thin film radially, thus preventing hot lubricant carry-over into the ensuing bearing sector. Additionally, the chevron shaped trailing edge induces vortical mixing of the hot lubricant with the gas that is naturally resident within the inter-pad region of a foil thrust bearing. The elimination of hot gas carry-over in combination with the enhanced mixing has enabled a completely passive thermally managed foil bearing design. Laboratory testing at NASA has confirmed the original analysis and reduced this concept to practice.

  3. Optimization of Spherical Roller Bearing Design Using Artificial Bee Colony Algorithm and Grid Search Method

    Science.gov (United States)

    Tiwari, Rajiv; Waghole, Vikas

    2015-07-01

    Bearing standards impose restrictions on the internal geometry of spherical roller bearings. Geometrical and strength constraints conditions have been formulated for the optimization of bearing design. The long fatigue life is one of the most important criteria in the optimum design of bearing. The life is directly proportional to the dynamic capacity; hence, the objective function has been chosen as the maximization of dynamic capacity. The effect of speed and static loads acting on the bearing are also taken into account. Design variables for the bearing include five geometrical parameters: the roller diameter, the roller length, the bearing pitch diameter, the number of rollers, and the contact angle. There are a few design constraint parameters which are also included in the optimization, the bounds of which are obtained by initial runs of the optimization. The optimization program is made to run for different values of these design constraint parameters and a range of the parameters is obtained for which the objective function has a higher value. The artificial bee colony algorithm (ABCA) has been used to solve the constrained optimized problem and the optimum design is compared with the one obtained from the grid search method (GSM), both operating independently. Both the ABCA and the GSM have been finally combined together to reach the global optimum point. A constraint violation study has also been carried out to give priority to the constraint having greater possibility of violations. Optimized bearing designs show a better performance parameter with those specified in bearing catalogs. The sensitivity analysis of bearing parameters has also been carried out to see the effect of manufacturing tolerance on the objective function.

  4. Designing functionally graded materials with superior load-bearing properties.

    Science.gov (United States)

    Zhang, Yu; Sun, Ming-Jie; Zhang, Denzil

    2012-03-01

    Ceramic prostheses often fail from fracture and wear. We hypothesize that these failures may be substantially mitigated by an appropriate grading of elastic modulus at the ceramic surface. In this study, we elucidate the effect of elastic modulus profile on the flexural damage resistance of functionally graded materials (FGMs), providing theoretical guidelines for designing FGMs with superior load-bearing property. The Young's modulus of the graded structure is assumed to vary in a power-law relation with a scaling exponent n; this is in accordance with experimental observations from our laboratory and elsewhere. Based on the theory for bending of graded beams, we examine the effect of n value and bulk-to-surface modulus ratio (E(b)/E(s)) on stress distribution through the graded layer. Theory predicts that a low exponent (0.15graded materials with various n values and E(b)/E(s) ratios can be fabricated by infiltrating alumina and zirconia with a low-modulus glass. Flexural tests show that graded alumina and zirconia with suitable values of these parameters exhibit superior load-bearing capacity, 20-50% higher than their homogeneous counterparts. Improving load-bearing capacity of ceramic materials could have broad impacts on biomedical, civil, structural, and an array of other engineering applications.

  5. Characteristics analysis and dynamic responses of micro-gas-lubricated journal bearings with a new slip model

    Science.gov (United States)

    Zhang, Wen-Ming; Meng, Guang; Huang, Hai; Zhou, Jian-Bin; Chen, Jie-Yu; Chen, Di

    2008-08-01

    In this paper, a new slip model based on kinetic theory of gases for gas-lubricated journal bearings in micro-electro-mechanical systems (MEMS) is applied using a physical approach. The corresponding modified governing equation and mathematic model are presented and the flow rate is plotted versus the inverse Knudsen number. Pressure distributions along the gas bearing at various Knudsen numbers and bearing numbers are plotted and the load carrying capacities are also obtained. A numerical analysis of a rigid rotor supported by gas-lubricated journal bearings is presented for dynamic behaviour. The slip flow effect on the properties, including pressure distribution, load carrying capacity and dynamic coefficients, of the micro-gas-lubricated journal bearings and dynamic responses of the micro rotor-bearing system are estimated and analysed in detail. It is shown that the dynamic coefficients increase with increasing bearing number except for two damping coefficients and the rotor-bearing system runs at a much higher rotating speed to keep stable when slip flow occurs. Moreover, the oscillation period of the rotor operating with the slip model is longer than that with the continuum flow. In addition, the whirl frequency is reduced from 0.422 to 0.079 under the slip effect. Therefore, the results of this study contribute to a further understanding of the characteristics and nonlinear dynamics of gas-film rotor-bearing systems in MEMS.

  6. The correct "ball bearings" data.

    Science.gov (United States)

    Caroni, C

    2002-12-01

    The famous data on fatigue failure times of ball bearings have been quoted incorrectly from Lieblein and Zelen's original paper. The correct data include censored values, as well as non-fatigue failures that must be handled appropriately. They could be described by a mixture of Weibull distributions, corresponding to different modes of failure.

  7. Losses of Superconductor Journal Bearing

    Science.gov (United States)

    Han, Y. H.; Hull, J. R.; Han, S. C.; Jeong, N. H.; Oh, J. M.; Sung, T. H.

    2004-06-01

    A high-temperature superconductor (HTS) journal bearing was studied for rotational loss. Two HTS bearings support the rotor at top and bottom. The rotor weight is 4 kg and the length is about 300 mm. Both the top and bottom bearings have two permanent magnet (PM) rings with an iron pole piece separating them. Each HTS journal bearing is composed of six pieces of superconductor blocks of size 35×25×10 mm. The HTS blocks are encased in a cryochamber through which liquid nitrogen flows. The inner spool of the cryochamber is made from G-10 to reduce eddy current loss, and the rest of the cryochamber is stainless steel. The magnetic field from the PM rings is < 10 mT on the stainless part. The rotational drag was measured over the same speed range at several chamber pressures. Results indicate that a chamber pressure of 0.4 mtorr is sufficiently low to minimize windage loss, and the 10 mT design criterion for the magnetic field on the stainless part of the cryochamber is too high.

  8. Vedr.: Military capacity building

    DEFF Research Database (Denmark)

    Larsen, Josefine Kühnel; Struwe, Lars Bangert

    2013-01-01

    Kühnel Larsen and researcher Lars Bangert Struwe of CMS had organized a seminar in collaboration with Royal Danish Defense Colleg and the East African Security Governance Network. The seminar focused on some of the risks involved in Military capacity building and how these risks are dealt with from......Military capacity building has increasingly become an integral part of Danish defence. Military capacity is a new way of thinking Danish defence and poses a new set of challenges and opportunities for the Danish military and the Political leadership. On the 12th of december, PhD. Candidate Josefine...

  9. 带栓钉型钢混凝土组合构件受力性能及承载力计算方法研究%RESEARCH ON MECHANICAL BEHAVIOR AND BEARING CAPACITY CALCULATION METHOD OF STEEL REINFORCED RECYCLE AGGREGATE CONCRETE COMBINED COMPONENT WITH STUD CONNECTERS

    Institute of Scientific and Technical Information of China (English)

    郑华海; 陈宗平; 苏益声

    2016-01-01

    Displacement controlled loading method was used to conduct push-out test of 7 SRC combined component specimens with studs and 1 specimen without studs.By considering stud diameter,stud positions and concrete compressive strength,SRC specimens'failure pattern,bond behaviour and stud shear capacity were investigated.The results showed that stud shear capacity was enhanced by increasing concrete compressive strength or stud diameter;studs set in web specimens 'shear performance was more effective than studs set in flange;while studs were set in flange and web,specimens'carrying performance was the best,and the free end slid could be effectively limited.This paper made a comparison of several formulas given by different countries for calculating shear capacity,and pointed out the rational application range of different design methods.At last,the shear capacity calculation method for steel no-buried stud was put forward based on analyzing the test results.%采用位移控制的加载方法对7个设置栓钉的型钢混凝土组合构件和1个未设置栓钉的对比试件进行推出试验.以栓钉直径、栓钉设置位置以及混凝土强度等为变化参数,研究型钢混凝土组合构件的破坏形态、黏结性能和极限受剪承载力.试验结果表明:栓钉受剪承载力随栓钉直径的增大、混凝土强度的提高而提高;腹板设置栓钉的试件抗剪性能优于翼缘的;翼缘和腹板均设置栓钉的试件承载性能最好,且能有效地限制滑移向自由端发展.分别对国内外不同技术标准建议的栓钉受剪承载力计算式进行分析比较,指出不同设计方法的合理应用范围.最后,在分析试验结果基础上提出型钢非埋入式栓钉受剪承载力的计算方法.

  10. A Novel Noncontact Ultrasonic Levitating Bearing Excited by Piezoelectric Ceramics

    Directory of Open Access Journals (Sweden)

    He Li

    2016-10-01

    Full Text Available A novel ultrasonic levitating bearing excited by three piezoelectric transducers is presented in this work. The transducers are circumferentially equispaced in a housing, with their center lines going through the rotation center of a spindle. This noncontact bearing has the ability to self-align and carry radical and axial loads simultaneously. A finite element model of the bearing is built in ANSYS, and modal analysis and harmonious response analysis are conducted to investigate its characteristics and driving parameters. Based on nonlinear acoustic theory and a thermodynamic theory of ideal gas, the radical and lateral load-carrying models are built to predict the bearing’s carrying capacity. In order to validate the bearing’s levitation force, a test system is established and levitating experiments are conducted. The experimental data match well with the theoretical results. The experiments reveal that the maximum radical and axial levitating loads of the proposed bearing are about 15 N and 6 N, respectively, when the piezoelectric transducers operate at a working frequency of 16.11 kHz and a voltage of 150 Vp-p.

  11. Fatigue Damage Mechanism of Oil Film Bearing Sleeve

    Institute of Scientific and Technical Information of China (English)

    HUANG Qing-xue; WANG Jian-mei; MA Li-feng; ZHAO Chun-jiang

    2007-01-01

    With the rapid development of the steel industry, to keep pace with the current trend of high speed, continuous, and large-scale production that focuses on automation and high levels of efficiency, many state-owned steel companies are being equipped with oil film bearings. Through long-term on-spot inspection and research on the fatigue failure of oil film bearing, three segments of annulated fatigue breakage were found axially along the inner surface of the bearing sleeve. In order to elucidate the reason for the three-segment annulated damage under rolling load, numerical boundary element method was adopted to analyze the contact behaviors between the sleeve and rollneck. Failure mechanism was discussed in detail, the distributions of contact stress were analyzed, and the service lives of the sleeve for different positions on the inner surface were quantitatively described, which provided an effective means to decrease wear and adhesive damage of the sleeve and to increase the load capacity of oil film bearing and its service life as well.

  12. Novel Super-Elastic Materials for Advanced Bearing Applications

    Science.gov (United States)

    Dellacorte, Christopher

    2014-01-01

    Tribological surfaces of mechanical components encounter harsh conditions in terrestrial, marine and aerospace environments. Brinell denting, abrasive wear and fatigue often lead to life-limiting bearing and gear failures. Novel superelastic materials based upon Ni-Ti alloys are an emerging solution. Ni-Ti alloys are intermetallic materials that possess characteristics of both metals and ceramics. Ni-Ti alloys have intrinsically good aqueous corrosion resistance (they cannot rust), high hardness, relatively low elastic modulus, are chemically inert and readily lubricated. Ni-Ti alloys also belong to the family of superelastics and, despite high hardness, are able to withstand large strains without suffering permanent plastic deformation. In this paper, the use of hard, resilient Ni-Ti alloys for corrosion-proof, shockproof bearing and gear applications are presented. Through a series of bearing and gear development projects, it is demonstrated that Ni-Tis unique blend of materials properties lead to significantly improved load capacity, reduced weight and intrinsic corrosion resistance not found in any other bearing materials. Ni-Ti thus represents a new materials solution to demanding tribological applications.

  13. Active control of multi-input hydraulic journal bearing system

    Science.gov (United States)

    Chuang, Jen-Chen; Chen, Chi-Yin; Tu, Jia-Ying

    2016-09-01

    Because of the advantages of high accuracy, high capacity, and low friction, the development of hydrostatic bearing for machine tool receives significant attention in the last decades. The mechanics and mechanical design of hydrostatic journal bearing with capillary restrictors has been discussed in literature. However, pragmatically, the undesired loading effects of cutting force tend to result in resonance and instability of the rotor and damage the shaft during operation. Therefore, multi-input, active flow control using state feedback design is proposed in this paper. To this purpose, the proportional pressure valves are added to the hydraulic system as active control devices, and the linearised models of the bearing and valve are discussed and identified. Simulation and experimental work is conducted to verify the proposed active control and parameter identification techniques. The results show that the unbalance responses of the rotor are reduced by the proposed state feedback controller, which is able to regulate the flow pressure effectively, thus enhancing the stability and accuracy of the hydraulic journal bearing.

  14. Performance characteristics in hydrodynamic water cooled thrust bearings

    Directory of Open Access Journals (Sweden)

    Farooq Ahmad Najar

    2016-09-01

    Full Text Available This paper deals with the study of the influence on performance characteristics of a thrust bearing with the introduction of cooling circuit and flow velocity of coolant within the designed thrust bearings is described. New method of cooling circuit configuration is taken into consideration and water has been chosen as a coolant here in the present work. Flow velocity of coolant, ranging from 0.5m/s to 2.0m/s is proposed. The Finite difference based numerical model has been developed in order to notice the effect on the heat transfer on a large hydrodynamic lubrication thrust bearing in-terms of its performance characteristics. In the present work, the solution of Reynolds equation, an energy equation with viscosity variation and Fourier heat conduction equations, applied with appropriate boundary conditions. From the present investigation, it is observed significant amount of heat content is removed from the bearing with the increase of flow velocity of coolant in an embedded cooling duct within the pad. An important parameter among performance characteristics has prevailed a significant increase in hydrodynamic pressure generation which in turn subsequently increases the load carrying capacity which has been never ever documented in the background literature.

  15. Characterization of Fault Size in Bearings

    Science.gov (United States)

    2014-12-23

    0.3 and 1.2 mm into the outer-race of the bearing, which simulates realistic faults that often can be found in damaged bearings. A 3D dynamic model ...3 4. MODEL DESCRIPTION A 3D dynamic ball bearing model was developed to study the effect of faults on the bearing dynamic behavior. The aim of the...understanding of the effects of fault size on the bearing dynamics. The research methodology combines dynamic modeling of the faulty bearing with

  16. Cavitation Estimates by Orbit Prediction of a Journal Bearing - Finite Element Modelling and Experimental Studies Cavitation Estimates by Orbit Prediction of a Journal Bearing - Finite Element Modelling and Experimental Studies

    DEFF Research Database (Denmark)

    Christiansen, Christian Kim; Klit, Peder; Walther, Jens Honore;

    2015-01-01

    The paper presents a two-sided approach to establish understanding of the cavitation phenomenon in dynamically loaded journal bearings, more specifically the engine bearings of large two-stroke marine diesel engines. One disadvantage of the journal bearing is the converging-diverging geometry...... making it prone to cavitation which again affects the load carrying capacity of the bearing. In combustion engines the journal bearing plays a vital role especiallyas main and crosshead bearings transmitting the combustion forces. Those forces vary highly during one combustion cycle which is further....... Validation of the results is done against the Ruston and Hornsby 6VEB-X Mk III engine. Besides the numerical investigations a cavitation test rig has been developed. With this rig it is possible to generate cavitation under controlled conditions in terms ofload/eccentricity and rotational speed...

  17. Simulation of Plain Bearings in Turbo-Generators Using the Stand ISO7902

    Directory of Open Access Journals (Sweden)

    Alejandra Elena García Toll

    2011-02-01

    Full Text Available The study of plain bearings is fundamental in guaranteeing the full running and maintenance of machines. Due to the fluctuations in working conditions, the simulation of plain bearing in turbines and generators has become increasingly necessary. The procedure used to obtain data is based on ISO Standards 7902:1998 which involves the calculation of the load capacity of plain bearings under hydrodynamic lubricant conditions. This method can be used to determine if the plain bearing under load and working conditions will be able to form and maintain a film of lubricant which is important to separate completely the shaft and bearing sliding surfaces in order to prevent friction between these two. Also, with this method it is possible to determine the ideal working conditions and limiting factors in the functioning of plain bearing. Some of these factors are: relative bearing clearance, shaft velocity, lubricant viscosity, diameter and width of bearing, average peak-to-valley height of sliding surfaces and nominal radial. Additionally, a calculation sample is presented

  18. Journal and Wave Bearing Impedance Calculation Software

    Science.gov (United States)

    Hanford, Amanda; Campbell, Robert

    2012-01-01

    The wave bearing software suite is a MALTA application that computes bearing properties for user-specified wave bearing conditions, as well as plain journal bearings. Wave bearings are fluid film journal bearings with multi-lobed wave patterns around the circumference of the bearing surface. In this software suite, the dynamic coefficients are outputted in a way for easy implementation in a finite element model used in rotor dynamics analysis. The software has a graphical user interface (GUI) for inputting bearing geometry parameters, and uses MATLAB s structure interface for ease of interpreting data. This innovation was developed to provide the stiffness and damping components of wave bearing impedances. The computational method for computing bearing coefficients was originally designed for plain journal bearings and tilting pad bearings. Modifications to include a wave bearing profile consisted of changing the film thickness profile given by an equation, and writing an algorithm to locate the integration limits for each fluid region. Careful consideration was needed to implement the correct integration limits while computing the dynamic coefficients, depending on the form of the input/output variables specified in the algorithm.

  19. CO diffusion capacity

    Energy Technology Data Exchange (ETDEWEB)

    Mielke, U.

    1979-01-01

    We measured in 287 persons the pulmonary CO diffusion capacity with the steady-state and the single breath methods, applying apnoeic periods of 4 and 10 seconds duration. The aspects methodical significance, polyclinical applicability and pathognostic relevance with respect to other approved pulmonary functional tests are discussed. Differing pulmonary diffusion capacity values found in normal persons or in patients suffering from silicosis, pulmonary fibrosis, Boeck's disease or rheumatoid arthritis, were investigated and critically evaluated.

  20. Revisiting Absorptive Capacity

    DEFF Research Database (Denmark)

    de Araújo, Ana Luiza Lara; Ulhøi, John Parm; Lettl, Christopher

    Absorptive capacity has mostly been perceived as a 'passive' outcome of R&D investments. Recently, however, a growing interest into its 'proactive' potentials has emerged. This paper taps into this development and proposes a dynamic model for conceptualizing the determinants of the complementary...... learning processes of absorptive capacity, which comprise combinative and adaptive capabilities. Drawing on survey data (n=169), the study concludes that combinative capabilities primarily enhance transformative and exploratory learning processes, while adaptive capabilities strengthen all three learning...

  1. Hybrid Superconducting Magnetic Bearing (HSMB) for high load devices

    Science.gov (United States)

    McMichael, C. K.; Ma, K. B.; Lamb, M. A.; Lin, M. W.; Chow, L.; Meng, R. L.; Hor, P. H.; Chu, W. K.

    1992-05-01

    Lifting capacities greater than 41 N/cm(exp 2) (60 psi) at 77 K have been achieved with a new type of levitation (hybrid) using a combination of permanent magnets and high quality melt-mixtured YBa2Cu3O(7-delta) (YBCO). The key concept of the hybrid superconducting magnetic bearing (HSMB) is the use of strong magnetic repulsion and attraction from permanent magnets for high levitation or suspension forces in conjunction with a superconductor's flux pinning characteristics to counteract the inherent instabilities in a system consisting of magnets only. To illustrate this concept, radial and axial forces between magnet/superconductor, magnet/magnet, and magnet/superconductor/magnet, were measured and compared for the thrust bearing configuration

  2. Brown bear telemetry and trapping: Special report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Brown bear studies were continued during the 1967 field season with emphasis on development of techniques for instrumenting bears with radio transmitters and...

  3. Live-trapping and handling brown bear

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This paper reports techniques developed to live trap and handle brown bears on the Kodiak National Wildlife Refuge. The brown bears (Ursus middendorffi) on the...

  4. Rolling Element Bearing Stiffness Matrix Determination (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Y.; Parker, R.

    2014-01-01

    Current theoretical bearing models differ in their stiffness estimates because of different model assumptions. In this study, a finite element/contact mechanics model is developed for rolling element bearings with the focus of obtaining accurate bearing stiffness for a wide range of bearing types and parameters. A combined surface integral and finite element method is used to solve for the contact mechanics between the rolling elements and races. This model captures the time-dependent characteristics of the bearing contact due to the orbital motion of the rolling elements. A numerical method is developed to determine the full bearing stiffness matrix corresponding to two radial, one axial, and two angular coordinates; the rotation about the shaft axis is free by design. This proposed stiffness determination method is validated against experiments in the literature and compared to existing analytical models and widely used advanced computational methods. The fully-populated stiffness matrix demonstrates the coupling between bearing radial, axial, and tilting bearing deflections.

  5. Goose Eggs Could Save Polar Bears

    Institute of Scientific and Technical Information of China (English)

    孙淑敏

    2009-01-01

    Polar bears could avoid extinction despitemany starving to death in coming years, ac-cording to scientists and other observers whohave discovered that some of the bears havefound a new food source--goose and duckeggs.

  6. Stable isotopes to detect food-conditioned bears and to evaluate human-bear management

    Science.gov (United States)

    Hopkins, John B.; Koch, Paul L.; Schwartz, Charles C.; Ferguson, Jake M.; Greenleaf, Schuyler S.; Kalinowski, Steven T.

    2012-01-01

    We used genetic and stable isotope analysis of hair from free-ranging black bears (Ursus americanus) in Yosemite National Park, California, USA to: 1) identify bears that consume human food, 2) estimate the diets of these bears, and 3) evaluate the Yosemite human–bear management program. Specifically, we analyzed the isotopic composition of hair from bears known a priori to be food-conditioned or non-food-conditioned and used these data to predict whether bears with an unknown management status were food-conditioned (FC) or non-food-conditioned (NFC). We used a stable isotope mixing model to estimate the proportional contribution of natural foods (plants and animals) versus human food in the diets of FC bears. We then used results from both analyses to evaluate proactive (population-level) and reactive (individual-level) human–bear management, and discussed new metrics to evaluate the overall human–bear management program in Yosemite. Our results indicated that 19 out of 145 (13%) unknown bears sampled from 2005 to 2007 were food-conditioned. The proportion of human food in the diets of known FC bears likely declined from 2001–2003 to 2005–2007, suggesting proactive management was successful in reducing the amount of human food available to bears. In contrast, reactive management was not successful in changing the management status of known FC bears to NFC bears, or in reducing the contribution of human food to the diets of FC bears. Nine known FC bears were recaptured on 14 occasions from 2001 to 2007; all bears were classified as FC during subsequent recaptures, and human–bear management did not reduce the amount of human food in the diets of FC bears. Based on our results, we suggest Yosemite continue implementing proactive human–bear management, reevaluate reactive management, and consider removing problem bears (those involved in repeated bear incidents) from the population.

  7. Grease lubrication mechanisms in bearing seals

    OpenAIRE

    2011-01-01

    Rolling bearings contain seals to keep lubricant inside and contaminants outside the bearing system. These systems are often lubricated with grease; the grease acts as a lubricant for the bearing and seal and improves the sealing efficiency. In this thesis, the influence of lubricating grease on bearing seal performance is studied. Rheological properties of the grease, i.e. shear stress and normal stress difference, are evaluated and related to the lubricating and sealing performance of the s...

  8. Thin film superconductor magnetic bearings

    Science.gov (United States)

    Weinberger, Bernard R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

  9. Cryptosporidiosis in a black bear in Virginia.

    Science.gov (United States)

    Duncan, R B; Caudell, D; Lindsay, D S; Moll, H D

    1999-04-01

    Cryptosporidiosis has not been previously reported in black bears in North America, either free-roaming or captive. However, oocysts have been documented in two captive Malayan sun bears (Helarctos malayanus) located in zoological parks in Taiwan. Developmental stages of Cryptosporidium parvum were observed in tissue sections from the small intestine of a black bear cub found dead in Virginia (USA).

  10. Bearing-Mounting Concept Accommodates Thermal Expansion

    Science.gov (United States)

    Nespodzany, Robert; Davis, Toren S.

    1995-01-01

    Pins or splines allow radial expansion without slippage. Design concept for mounting rotary bearing accommodates differential thermal expansion between bearing and any structure(s) to which bearing connected. Prevents buildup of thermal stresses by allowing thermal expansion to occur freely but accommodating expansion in such way not to introduce looseness. Pin-in-slot configuration also maintains concentricity.

  11. Analysis of the Journal Bearing Performance of a Reciprocating Compressor Using Methane

    Directory of Open Access Journals (Sweden)

    Oghenevwaire, Ogheneovo Emmanuel

    2014-04-01

    Full Text Available The performance of the journal bearing of a reciprocating compressor is crutial in industrial applications utilizing reciprocating compressors systems. This study analyzes a system utilizing EXXCOLUB SLG 190 as lubricant and methane, as the compressed gas. Numerical method, specifically the finite element method, is utilized in this study. Reynolds equation is analyzed using the half sommerfield boundary condition. The analysis encompasses a study of the effect of viscosity thinning with solubility of the methane at various operating pressures on the pressure profile and the load capacity of the bearing. The effect of vibration on the performance of the journal bearing is also analyzed by considering the effect of vertical flow. It was observed that the maximum pressure reduced by 50% as well as the load capacity of the journal bearing, when the operating pressure was increased from 0 to 5000 psi (3.447×107 N/m2. The pressure profile flattens out as the operating pressure increases. Increase in vibration (vertical flow effect results in the reduction of load capacity of the journal bearing.

  12. Nano-level instrumentation for analyzing the dynamic accuracy of a rolling element bearing

    Science.gov (United States)

    Yang, Z.; Hong, J.; Zhang, J.; Wang, M. Y.; Zhu, Y.

    2013-12-01

    The rotational performance of high-precision rolling bearings is fundamental to the overall accuracy of complex mechanical systems. A nano-level instrument to analyze rotational accuracy of high-precision bearings of machine tools under working conditions was developed. In this instrument, a high-precision (error motion spindle was applied to spin the test bearing. Operating conditions could be simulated effectively because of the large axial loading capacity. An air-cylinder, controlled by a proportional pressure regulator, was applied to drive an air-bearing subjected to non-contact and precise loaded axial forces. The measurement results on axial loading and rotation constraint with five remaining degrees of freedom were completely unconstrained and uninfluenced by the instrument's structure. Dual capacity displacement sensors with 10 nm resolution were applied to measure the error motion of the spindle using a double-probe error separation method. This enabled the separation of the spindle's error motion from the measurement results of the test bearing which were measured using two orthogonal laser displacement sensors with 5 nm resolution. Finally, a Lissajous figure was used to evaluate the non-repetitive run-out (NRRO) of the bearing at different axial forces and speeds. The measurement results at various axial loadings and speeds showed the standard deviations of the measurements' repeatability and accuracy were less than 1% and 2%. Future studies will analyze the relationship between geometrical errors and NRRO, such as the ball diameter differences of and the geometrical errors in the grooves of rings.

  13. Study on water lubricated bearings of high speed pump based on numerical simulation

    Science.gov (United States)

    Bai, Y. X.; Kong, F. Y.; Sun, J. R.; Yuan, X.

    2016-05-01

    A method is presented for calculating and analyzing the performance of water lubricated bearing of high speed pump under different structure. In present work, six kinds of bearings in different radial clearance(C), which are 0.02, 0.04, 0.06, 0.08, 0.10and0.12 respectively, under the same minimum water film thickness, have been designed. The models are built by CREO and numerical simulated by ansys. The main content of the present work is to analyze the relationship between the pressure and the load carrying capacity with different radial clearance(C) by ansys workbench based on Fluid-Solid coupling through ansys workbench.The stress deformations of bearings are also acquired through thermal-structure coupling. From the comparing result among the numerical analysis under the six different model of water lubricated bearing, the relationship between radial clearance(C) and load carrying capacity, as well as the deformation of bearing under different radial clearance(C), are obtained. Further, results indicates that, a proper selection of radial clearance(C) is essential to enhance the bearing performance.

  14. Geothermal Plant Capacity Factors

    Energy Technology Data Exchange (ETDEWEB)

    Greg Mines; Jay Nathwani; Christopher Richard; Hillary Hanson; Rachel Wood

    2015-01-01

    The capacity factors recently provided by the Energy Information Administration (EIA) indicated this plant performance metric had declined for geothermal power plants since 2008. Though capacity factor is a term commonly used by geothermal stakeholders to express the ability of a plant to produce power, it is a term frequently misunderstood and in some instances incorrectly used. In this paper we discuss how this capacity factor is defined and utilized by the EIA, including discussion on the information that the EIA requests from operations in their 923 and 860 forms that are submitted both monthly and annually by geothermal operators. A discussion is also provided regarding the entities utilizing the information in the EIA reports, and how those entities can misinterpret the data being supplied by the operators. The intent of the paper is to inform the facility operators as the importance of the accuracy of the data that they provide, and the implications of not providing the correct information.

  15. Capacity Maximizing Constellations

    Science.gov (United States)

    Barsoum, Maged; Jones, Christopher

    2010-01-01

    Some non-traditional signal constellations have been proposed for transmission of data over the Additive White Gaussian Noise (AWGN) channel using such channel-capacity-approaching codes as low-density parity-check (LDPC) or turbo codes. Computational simulations have shown performance gains of more than 1 dB over traditional constellations. These gains could be translated to bandwidth- efficient communications, variously, over longer distances, using less power, or using smaller antennas. The proposed constellations have been used in a bit-interleaved coded modulation system employing state-ofthe-art LDPC codes. In computational simulations, these constellations were shown to afford performance gains over traditional constellations as predicted by the gap between the parallel decoding capacity of the constellations and the Gaussian capacity

  16. Dual capacity reciprocating compressor

    Science.gov (United States)

    Wolfe, Robert W.

    1984-01-01

    A multi-cylinder compressor 10 particularly useful in connection with northern climate heat pumps and in which different capacities are available in accordance with reversing motor 16 rotation is provided with an eccentric cam 38 on a crank pin 34 under a fraction of the connecting rods, and arranged for rotation upon the crank pin between opposite positions 180.degree. apart so that with cam rotation on the crank pin such that the crank throw is at its normal maximum value all pistons pump at full capacity, and with rotation of the crank shaft in the opposite direction the cam moves to a circumferential position on the crank pin such that the overall crank throw is zero. Pistons 24 whose connecting rods 30 ride on a crank pin 36 without a cam pump their normal rate with either crank rotational direction. Thus a small clearance volume is provided for any piston that moves when in either capacity mode of operation.

  17. Capacity at Railway Stations

    DEFF Research Database (Denmark)

    Landex, Alex

    2011-01-01

    special focus when conducting UIC 406 capacity analyses.This paper describes how the UIC 406 capacity method can be expounded for stations. Commonly for the analyses of the stations it is recommended to include the entire station including the switch zone(s) and all station tracks. By including the switch...... zone(s) the possible conflicts with other trains (also in the opposite direction) are taken into account leading to more trustworthy results. Although the UIC 406 methodology proposes that the railway network should be divided into line sections when trains turn around and when the train order...... is changed, this paper recommends that the railway lines are not always be divided. In case trains turn around on open (single track) line, the capacity consumption may be too low if a railway line is divided. The same can be the case if only few trains are overtaken at an overtaking station. For dead end...

  18. Weather and road capacity

    DEFF Research Database (Denmark)

    Jensen, Thomas Christian

    2014-01-01

    The paper presents estimations of the effect of bad weather on the observed speed on a Danish highway section; Køge Bugt Motorvejen. The paper concludes that weather, primarily precipitation and snow, has a clear negative effect on speed when the road is not in hypercongestion mode. Furthermore......, the capacity of the highway seems to be reduced in bad weather and there are indications that travel time variability is also increased, at least in free-flow conditions. Heavy precipitation reduces speed and capacity by around 5-8%, whereas snow primarily reduces capacity. Other weather variables......-parametrically against traffic density and in step 2 the residuals from step 1 are regressed linearly against the weather variables. The choice of a non-parametric method is made to avoid constricting ties from a parametric specification and because the focus here is not on the relationship between traffic flow...

  19. Cannibalism and predation on black bears by grizzly bears in the Yellowstone ecosystem, 1975-1990

    Science.gov (United States)

    Mattson, D.J.; Knight, R.R.; Blanchard, B.M.

    1992-01-01

    We documented one instance of an adult male grizzly bear preying upon a black bear and four instances where circumstantial evidence suggested that grizzly bears (two cubs-of-the-year, one yearling female that was injured, and one adult male) had been preyed upon by conspecifics. We also examined feces of grizzly bears for bear remains. Remains of bears tended to be more common in spring feces and did not differ in frequency between early and late years of the study. Our observations generally support existing hypotheses concerning cannibalism among bears.

  20. Improvement of journal bearing operation at heavy misalignment using bearing flexibility and compliant liners

    DEFF Research Database (Denmark)

    Thomsen, Kim; Klit, Peder

    2012-01-01

    A flexure journal bearing design is proposed that will improve operational behaviour of a journal bearing at pronounced misalignment. Using a thermoelastohydrodynamic model, it is shown that the proposed flexure journal bearing has vastly increased the hydrodynamic performance compared to the stiff...... bearing when misaligned. The hydrodynamic performance is evaluated on lubricant film thickness, pressure and temperature. Furthermore, the influence of a compliant bearing liner is investigated and it is found that it increases the hydrodynamic performance when applied to a stiff bearing, whereas...... the liner has practically no influence on the flexure journal bearing's performance....

  1. Shaft Center Orbit in Dynamically Loaded Bearings

    DEFF Research Database (Denmark)

    Klit, Peder

    The aim of this work is to demonstrate how to utilize the bearings damping coefficients to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker in 1965 and described further in 1972. Several authors have refined this method over...... Jorgen W. Lund pointed out in lecture notes that the dynamic damping coefficients of the bearing could be used to find the shaft orbit for dynamically loaded bearings. For simplicity the "Short-Width-Journal-Bearing Theory" is used as a basis for finding the damping coefficients in this work...

  2. Optimal design of Tilting-Pad Thrust Bearings with High Pressure Injection Pockets

    DEFF Research Database (Denmark)

    Heinrichson, Niels; Santos, Ilmar

    2006-01-01

    A thermo-elasto-hydrodynamic(TEHD) model based on the Reynolds equation has been used to study the effect of oil injection pockets on the performance of tilting pad thrust bearings. The optimal position of the pivot both with respect to load carrying capacity and minimal power consumption is seen...

  3. Simulation on Mechanical Behaviors of Oil-film Bearing Sleeve by Elastic Interference Fit

    Institute of Scientific and Technical Information of China (English)

    HUANG Qingxue; WANG Jianmei; ZHAO Chunjiang; MA Lifeng

    2006-01-01

    Oil film bearing, which works on thin film between sleeve and bush, is widely used in steel industry due to the characteristics of high efficiency and low noise, etc. The backup roll of 1 580PC hot strip mill invested by some steel corporation has been equipped with such bearing. During the process of setup&disassembly and usage period, the sleeve has been dramatically damaged, which results in production accidents and decreases its service life, thus heavily influencing steel production. Aimed at such puzzles, under specific loadcase, mechanical properties of bearing sleeve, as well as estimation of contact status and adhesive force of sleeve by interference fit, are quantitatively simulated by finite element method, which establishes an mechanical foundation for improving the load capacity of bearing and decreasing its wear and adhesion damages. Finally, some measures and conclusions are drawn.

  4. Chromatographic (TLC) differentiation of grizzly bear and black bear scats

    Science.gov (United States)

    Picton, Harold D.; Kendall, Katherine C.

    1994-01-01

    While past work concluded that thin-layer chromatography (TLC) was inadequate for the separation of grizzly (Ursus arctos horribilis) and black bear (U. americanus) scats, our study found differences adequate for species separation. A key was constructed using 19 of 40 data points recorded on each(N)=356 profiles of 178) know-species scat. Accuracy was best for late summer scats (94%). Methods for specimen preparation, analysis, and reading the TLC profiles are discussed. Factors involved in scat variation were tested.

  5. Pratt and Whitney cryogenic turbopump bearing experience

    Science.gov (United States)

    Poole, W. E.; Bursey, R. W., Jr.

    1988-01-01

    Successful, reusable bearings require lubrication, traditionally, a transfer film from sacrificial cage wear. Early testing included materials screening programs to identify suitable cryogenic cage materials. A specially developed element tester that simulated the function of a ball bearing cage was used. Suitable materials must provide lubrication with an acceptably low wear rate, without abrading contacting surfaces. The most promising materials were tested in full scale bearings at speeds up to 4 MDN. Teflon, filled with 40 percent bronze powder, was the best performing material. A variety of bearings were designed and successfully tested in LH2 and LOX. Bearings with bronze filled Teflon cages were successfully tested for 150 hrs. In overload tests, the same design was tested for 5 hrs at maximum Hertz stresses above 450 ksi and an additional 5 hrs with a maximum Hertz stress exceeding 500 ksi. Four bearings were tested in LOX for 25 hrs, with a maximum time per bearing of 10 hrs.

  6. Flood Bypass Capacity Optimization

    Science.gov (United States)

    Siclari, A.; Hui, R.; Lund, J. R.

    2015-12-01

    Large river flows can damage adjacent flood-prone areas, by exceeding river channel and levee capacities. Particularly large floods are difficult to contain in leveed river banks alone. Flood bypasses often can efficiently reduce flood risks, where excess river flow is diverted over a weir to bypasses, that incur much less damage and cost. Additional benefits of bypasses include ecosystem protection, agriculture, groundwater recharge and recreation. Constructing or expanding an existing bypass costs in land purchase easements, and levee setbacks. Accounting for such benefits and costs, this study develops a simple mathematical model for optimizing flood bypass capacity using benefit-cost and risk analysis. Application to the Yolo Bypass, an existing bypass along the Sacramento River in California, estimates optimal capacity that economically reduces flood damage and increases various benefits, especially for agriculture. Land availability is likely to limit bypass expansion. Compensation for landowners could relax such limitations. Other economic values could affect the optimal results, which are shown by sensitivity analysis on major parameters. By including land geography into the model, location of promising capacity expansions can be identified.

  7. Influence of unbalance levels on nonlinear dynamics of a rotor-backup rolling bearing system

    Science.gov (United States)

    Fonseca, Cesar A.; Santos, Ilmar F.; Weber, Hans I.

    2017-04-01

    Rotor drops in magnetic bearing and unbalance in rotors have been objective of study for many years. The combination of these two well-known phenomena led to an interesting chaotic response, when the rotor touches the inner race of the back-up bearing. The present work explores the nonlinear rotor backup bearing dynamics both theoretically and experimentally using a fully instrumented test rig, where the position of shaft, its angular velocity and the contact forces between the shaft and the backup bearing are sampled at 25 kHz. The test rig is built by a removable passive magnetic bearing, which allows for simulation of magnetic bearing failure (loss of carrying capacity and rotor fall). The rotor is studied numerically as well as experimentally. A theoretical approach is given beforehand and supplies the basis of the study. Finally the presented results are commented on the point of view of nonlinear dynamics applied to the practical use. The theoretical and numerical analyses are shown through orbit plots, phase plans, Poincaré maps, force response in time and double sided spectrum. The latter is important to characterize the condition at different levels of unbalance between forward and backward whirl. Our preliminary results indicate that for smaller amount of unbalance the rotor swings at the bottom of the bearing, the more the unbalance increases, other dynamical behavior occur and some can be extremely harmful, since the rotor can be lifted from the contact state and return, starting to impact innumerable times without reaching a steady state.

  8. Effects of operation temperature on thermal expansion and main parameters of radial ball bearings

    Directory of Open Access Journals (Sweden)

    Mitrović Radivoje M.

    2015-01-01

    Full Text Available The research of influence of operation temperature on the thermal expansion and main parameters of radial ball bearings is presented in this paper. The main bearing parameters are identified in accordance with the increasing requests concerning stability and load capacity. A series of Finite Element Analyses is performed for quasi-static analysis of all identified bearing parameters during contact period in referent temperature. Then, the dependence of bearing material characteristics on the operation temperature is discussed. Few series of Finite Element Analyses are performed for a particular radial ball bearing type, with characteristics in accordance with manufacturer specifications, for several operation temperatures. These two problems analyses include consideration of relation between the initial radial clearance, thermal expansion strains and contact deformations of the parts of the bearing assembly. The results for radial ball bearing parameters are monitored during a ball contact period for different temperatures and the appropriate discussion and conclusions are given. The conclusions about the contribution of developed procedure in defining the optimum operation temperature range are shown. [Projekat Ministarstva nauke Republike Srbije, br. TR 35029 i br. OI 174001

  9. An AC-electromagnetic bearing for flywheel energy storage in space

    Science.gov (United States)

    Nikolajsen, Jorgen L.

    1993-01-01

    A repulsive type AC-electromagnetic bearing was developed and tested. It was conceived on the basis of the so-called Magnetic River suspension for high-speed trains. The appearance of the bearing is similar to the traditional DC-type electromagnetic bearing but the operating principle is different. The magnets are fed with alternating current instead of direct current and the rotor is fitted with a conducting sleeve (e.g. aluminum) instead of a ferromagnetic sleeve. The repulsion is due to induction of eddy-currents in the conducting sleeve. The bearing is inherently stable and requires no feedback control. It provides support in five degrees of freedom such that a short rotor may be fully supported by a single bearing. These capabilities were demonstrated experimentally. On the down side, the load carrying capacity and the damping obtained so far were quite low compared to the DC-type bearing. Also, significant heating of the conducting sleeve was experienced. The AC-bearing is essentially a modified induction motor and there are strong indications that it can be run both as a motor and as a generator with no commutator requirements. It is therefore considered to be a good candidate for support of energy storage flywheels in space.

  10. The role of superconductivity in magnetic bearings for high-load applications

    Science.gov (United States)

    Downer, James; Eisenhaure, David

    1993-01-01

    Slewing of large payloads will require control torque and angular momentum storage capacities that are large in comparison to the capabilities of available control moment gyros (CMG's). SatCon Technology Corporation is currently designing a CMG which may be employed as a slew actuator for large spacecraft or other payloads. The slew actuator employs a type of magnetic bearing which may be used in high load applications. The magnetic bearing is also used to fully gimbal the suspended rotor of the slew actuator. The use of magnetic bearings in angular momentum exchange actuators has the primary advantage that physical contact between the rotor and stator is eliminated. This leads to greatly extended life, increased reliability, and reduced vibrations. Several actuators operating on magnetic bearings have been demonstrated in previous research efforts. These were sized for use in small satellites. For conventional magnetic bearings, which employ magnetic cores, high torsional loading may require that the magnetic structure be excessively massive. An alternative magnetic bearing design which employs a superconducting coil and eliminates conventional magnetic structures is discussed. The baseline approach is to replace the field coil of a conventional magnetic bearing with the superconducting coil.

  11. Synthesis and characterization of porous microspheres bearing pyrrolidone units

    Energy Technology Data Exchange (ETDEWEB)

    Maciejewska, M., E-mail: mmacieje@umcs.pl; Kołodyńska, D.

    2015-01-15

    Porous microspheres of glycydyl methacrylate (GMA) cross-linked with trimethylolpropane trimethacrylate (TRIM) were prepared with toluene as porogen by suspension-emulsion polymerization. With increasing molar ratio of the functional monomer to cross-linker, the epoxy group content increases significantly whereas the parameters of porous structure (specific surface area and total pore volume) decreases. In order to obtain adsorbents bearing functional groups the porous methacrylate network was modified by subsequent reaction with pyrrolidone. The materials were studied using elemental analysis, infrared spectroscopy, atomic force microscopy (AFM), attenuated total reflection (ATR) spectroscopy, Raman spectroscopy, thermal gravimetry. Additionally, polymers sorption capacity towards Cu(II) was investigated. - Highlights: • Porous microspheres with reactive epoxy group were synthesized. • Highly developed porous structure was created. • Pyrrolidone units were incorporated during ring–opening reaction. • Polymers sorption capacity towards Cu (II) was investigated.

  12. Current leads and magnetic bearings

    Science.gov (United States)

    Hull, J. R.

    1993-10-01

    Since the discovery of high temperature superconductors (HTS's), Argonne National Laboratory (ANL) has been active in a broad spectrum of activities in developing these materials for applications. Work at every stage of development has involved industrial collaboration in order to accelerate commercialization. While most of the development work has been devoted to improving the properties of current-carrying wires, some effort has been devoted to applications that can utilize HTS's with properties available now or in the near future. In this paper, advances made in the area of current leads and magnetic bearings are discussed.

  13. Value for railway capacity

    DEFF Research Database (Denmark)

    Sameni, Melody Khadem; Preston, John M.

    2012-01-01

    Growth in rail traffic has not been matched by increases in railway infrastructure. Given this capacity challenge and the current restrictions on public spending, the allocation and the utilization of existing railway capacity are more important than ever. Great Britain has had the greatest growth...... DEA work on the economic efficiency of railways by considering a new combination of input-output that also incorporates quality of service. The constant and variable returns to scale models are applied to the case study of franchised passenger operators in Great Britain. The follow-up Tobit regression...... model shows positive correlation between serving London and the efficiency scores. There is negative correlation between offering regional services (average length of journeys less than 40 mi) and the efficiency scores. The overall study and the results can provide helpful insights for railway...

  14. Understanding adaptive capacity and capacity to innovate in social-ecological systems: Applying a gender lens.

    Science.gov (United States)

    Cohen, Philippa J; Lawless, Sarah; Dyer, Michelle; Morgan, Miranda; Saeni, Enly; Teioli, Helen; Kantor, Paula

    2016-12-01

    Development policy increasingly focuses on building capacities to respond to change (adaptation), and to drive change (innovation). Few studies, however, focus specifically on the social and gender differentiation of capacities to adapt and innovate. We address this gap using a qualitative study in three communities in Solomon Islands; a developing country, where rural livelihoods and well-being are tightly tied to agriculture and fisheries. We find the five dimensions of capacity to adapt and to innovate (i.e. assets, flexibility, learning, social organisation, agency) to be mutually dependant. For example, limits to education, physical mobility and agency meant that women and youth, particularly, felt it was difficult to establish relations with external agencies to access technical support or new information important for innovating or adapting. Willingness to bear risk and to challenge social norms hindered both women's and men's capacity to innovate, albeit to differing degrees. Our findings are of value to those aspiring for equitable improvements to well-being within dynamic and diverse social-ecological systems.

  15. Markets and Institutional Capacity

    DEFF Research Database (Denmark)

    Ingemann, Jan Holm

    2010-01-01

    Adequate explanations concerning the introduction of production and consumption of organic food in Denmark imply the necessity to engage a certain understanding of markets. Markets should subsequently not be seen as entities nor places but as complex relations between human actors. Further, the e......, the establishment, maintenance and development of markets are depending on the capacity of the actors to enter into continuous and enhancing interplay....

  16. Building Partner Capacity

    Science.gov (United States)

    2015-02-01

    In a similar manner, globalization has also created new realities, such as in the case of food production where choice now affects demand as much as...quantity did in the past. “Two major factors drive food requirements [and market prices]: a growing global population and prosperity that expands...argued earlier, to expend effort in other nations without consideration of building capacity and resiliency risks strategic failure and wastage of

  17. Stability and Load Bearing Capacity of a Bars with Built up Cross Section and Elastic Supports / Badania Stateczności I Nosności Prętów Złożonych Z Podporami Sprężystymi

    Science.gov (United States)

    Krajewski, Marcin

    2015-03-01

    The present paper is devoted to the numerical analysis and experimental tests of compressed bars with built-up cross section which are commonly used as a top chord of the roof trusses. The significant impact on carrying capacity for that kind of elements in case of out-of-plane buckling is appropriate choice of battens which are used to provide interaction between separate members. Linear buckling analysis results and nonlinear static analysis results, with material and geometrical nonlinearity, are presented for the bar with built-up cross section which was used as the top chord of the truss made in reality. Diagonals and verticals which are supports for the top chord between marginal joints were replaced by the elastic supports. The threshold stiffness (minimum stiffness) for the intermediate elastic supports which ensures maximum buckling load was appointed for the beam and shell model of the structure. The magnitude of limit load depended on length of the battens was calculated for models with initial geometric imperfections. The experimental tests results for the axially compressed bars with builtup cross section and elastic support are presented. Niniejsza praca poświecona jest analizom numerycznym i badaniom doświadczalnym ściskanych prętów złożonych, które są często stosowane, jako pasy górne kratownic dachowych. Istotny wpływ na nośność tego typu elementów, przy założeniu wyboczenia z płaszczyzny układu, ma odpowiedni dobór przewiązek zapewniający współpracę poszczególnych gałęzi. W pracy przedstawiono rezultaty liniowych analiz stateczności oraz fizycznie i geometrycznie nieliniowych analiz statycznych dla pręta złożonego, z którego zbudowany jest pas górny kratownicy wykonanej w rzeczywistości. Słupki i krzyżulce podpierające pas między węzłami skrajnymi zastąpiono podporami sprężystymi. Wyznaczono graniczną (minimalna) sztywność sprężystych podpór pośrednich zapewniającą maksymalną wartość obci

  18. Bearing Health Assessment Based on Chaotic Characteristics

    Directory of Open Access Journals (Sweden)

    Chen Lu

    2013-01-01

    Full Text Available Vibration signals extracted from rotating parts of machinery carry a lot of useful information about the condition of operating machine. Due to the strong non-linear, complex and non-stationary characteristics of vibration signals from working bearings, an accurate and reliable health assessment method for bearing is necessary. This paper proposes to utilize the selected chaotic characteristics of vibration signal for health assessment of a bearing by using self-organizing map (SOM. Both Grassberger-Procaccia algorithm and Takens' theory are employed to calculate the characteristic vector which includes three chaotic characteristics, such as correlation dimension, largest Lyapunov exponent and Kolmogorov entropy. After that, SOM is used to map the three corresponding characteristics into a confidence value (CV which represents the health state of the bearing. Finally, a case study based on vibration datasets of a group of testing bearings was conducted to demonstrate that the proposed method can reliably assess the health state of bearing.

  19. Competence building capacity shortage

    Energy Technology Data Exchange (ETDEWEB)

    Doorman, Gerard; Wangensteen, Ivar; Bakken, Bjoern

    2005-02-01

    The objective of the project 'Competence Building Capacity Shortage' has been 'to increase knowledge about central approaches aimed at solving the peaking capacity problem in restructured power systems'. With respect to reserve markets, a model was developed in the project to analyze the relations between reserve requirements and prices in the spot and reserve markets respectively. A mathematical model was also developed and implemented, which also includes the balance market, and has a good ability to predict the relations between these markets under various assumptions. With some further development, this model can be used fore realistic analyses of these markets in a Nordic context. It was also concluded that certain system requirements with respect to frequency and time deviation can be relaxed without adverse effects. However, the requirements to system bias, Frequency Activated Operating Reserves and Frequency Activated Contingency Reserves cannot be relaxed, the latter because they must cover the dimensioning fault in the system. On the other hand, Fast Contingency Reserves can be reduced by removing requirements to national balances. Costs can furthermore be reduced by increasingly adapting a Nordic as opposed to national approach. A model for stepwise power flow was developed in the project, which is especially useful to analyze slow power system dynamics. This is relevant when analysing the effects of reserve requirements. A model for the analysis of the capacity balance in Norway and Sweden was also developed. This model is useful for looking at the future balance under various assumptions regarding e.g. weather conditions, demand growth and the development of the generation system. With respect to the present situation, if there is some price flexibility on the demand side and system operators are able to use reserves from the demand side, the probability for load shedding during the peak load hour is close to zero under the weather

  20. Investigations of Slip Effect on the Performance of Micro Gas Bearings and Stability of Micro Rotor-Bearing Systems

    Directory of Open Access Journals (Sweden)

    Jieyu Chen

    2007-08-01

    Full Text Available Incorporating the velocity slip effect of the gas flow at the solid boundary, theperformance and dynamic response of a micro gas-bearing-rotor system are investigated inthis paper. For the characteristic length scale of the micro gas bearing, the gas flow in thebearing resides in the slip regime rather than in the continuum regime. The modifiedReynolds equations of different slip models are presented. Gas pressure distribution and loadcarrying capacity are obtained by solving the Reynolds equations with finite differentmethod (FDM. Comparing results from different models, it is found that the second orderslip model agrees reasonably well with the benchmarked solutions obtained from thelinearized Boltzmann equation. Therefore, dynamic coefficients derived from the secondorder slip model are employed to evaluate the linear dynamic stability and vibrationcharacteristics of the system. Compared with the continuum flow model, the slip effectreduces dynamic coefficients of the micro gas bearing, and the threshold speed for stableoperation is consequently raised. Also, dynamic analysis shows that the system responseschange with variation of the operating parameters including the eccentricity ratio, therotational speed, and the unbalance ratio.

  1. Electromechanical properties of radial active magnetic bearings

    OpenAIRE

    Antila, Matti

    1998-01-01

    Nonideal properties of the electromagnetic actuators in radial active magnetic bearings are studied. The two dimensional nonlinear stationary finite element method is used to determine the linearised parameters of a radial active magnetic bearing. The method is verified on two test machines. The accuracy is 10-15 % in the magnetic saturation region. The effect of magnetic saturation on the bearing dynamics is studied based on the root locus diagrams of the closed loop system. These diagrams s...

  2. Powder-Metallurgical Bearings For Turbopumps

    Science.gov (United States)

    Bhat, B. N.; Humphries, T. S.; Thom, R. L.; Moxson, V.; Friedman, G. I.; Dolan, F. J.; Shipley, R. J.

    1993-01-01

    Bearings fabricated by powder metallurgy developed for use in machines subjected to extremes of temperature, rolling-contact cyclic stresses, and oxidizing or otherwise corrosive fluids. Bearings also extend operating lives of other machines in which bearings required to resist extreme thermal, mechanical, and chemical stresses. One alloy exhibiting outstanding properties was MRC-2001. Resistance to fatigue, stress corrosion cracking, and wear found superior to that of 440C stainless steel.

  3. Are organohalogen contaminants a bears (Ursus maritimus)?

    DEFF Research Database (Denmark)

    Sonne, Christian; Dietz, Rune; Leifsson, PS

    2006-01-01

    Tissues of polar bears (Ursus maritimus) from East Greenland contain the highest concentrations of organohalogen contaminants (OHCs) among subpopulations of any mammalian species in the Arctic. Negative associations also have been found between OHC concentrations and bone mineral density and liver...... histology parameters for this subpopulation of polar bears. The present study examined the OHC concentrations and adverse effects on renal tissue for 75 polar bears collected during 1999 to 2002. Specific lesions were diffuse glomerular capillary wall thickening, mesangial glomerular deposits, tubular...

  4. Numerical modelling of the flow in the annular multi-recess hydrostatic thrust bearing using CFD methods

    Directory of Open Access Journals (Sweden)

    Drbáková S.

    2013-04-01

    Full Text Available The current research of hydrostatic bearings and hydrostatic slide-ways is far from being over. The topic is constantly evolving, creating new geometries of the sliding bearings, developing new types of friction materials and lubricants. The control elements of hydraulic mechanisms that serve to regulation of the hydrostatic bearings tipping are still in progress. Almost every application has different requirements for the bearings, whether in terms of loading capacity, speed rotation, and also the price. All these aspects should be included in the design of hydrostatic thrust bearings. Thanks to great advances in the development of computer technology and software for numerical modelling, we can simulate real movement of viscous fluids. To create a numerical model of hydrostatic thrust bearing, Ansys Fluent 14.0 software package has been applied. The article describes the basic methods of numerical modelling of the given problem and evaluates the pressure field and the loading capacity of annular multi-recess hydrostatic thrust bearing and its dependence on the change in static pressure.

  5. Nano-level instrumentation for analyzing the dynamic accuracy of a rolling element bearing

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Z.; Hong, J.; Zhang, J.; Wang, M. Y. [State Key Laboratory for Manufacturing Systems Engineering, Xi' an Jiaotong University, Xi' an (China); Zhu, Y. [Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, Xi' an Jiaotong University, Xi' an (China)

    2013-12-15

    The rotational performance of high-precision rolling bearings is fundamental to the overall accuracy of complex mechanical systems. A nano-level instrument to analyze rotational accuracy of high-precision bearings of machine tools under working conditions was developed. In this instrument, a high-precision (error motion < 0.15 μm) and high-stiffness (2600 N axial loading capacity) aerostatic spindle was applied to spin the test bearing. Operating conditions could be simulated effectively because of the large axial loading capacity. An air-cylinder, controlled by a proportional pressure regulator, was applied to drive an air-bearing subjected to non-contact and precise loaded axial forces. The measurement results on axial loading and rotation constraint with five remaining degrees of freedom were completely unconstrained and uninfluenced by the instrument's structure. Dual capacity displacement sensors with 10 nm resolution were applied to measure the error motion of the spindle using a double-probe error separation method. This enabled the separation of the spindle's error motion from the measurement results of the test bearing which were measured using two orthogonal laser displacement sensors with 5 nm resolution. Finally, a Lissajous figure was used to evaluate the non-repetitive run-out (NRRO) of the bearing at different axial forces and speeds. The measurement results at various axial loadings and speeds showed the standard deviations of the measurements’ repeatability and accuracy were less than 1% and 2%. Future studies will analyze the relationship between geometrical errors and NRRO, such as the ball diameter differences of and the geometrical errors in the grooves of rings.

  6. Gearbox Reliability Collaborative Bearing Calibration

    Energy Technology Data Exchange (ETDEWEB)

    van Dam, J.

    2011-10-01

    NREL has initiated the Gearbox Reliability Collaborative (GRC) to investigate the root cause of the low wind turbine gearbox reliability. The GRC follows a multi-pronged approach based on a collaborative of manufacturers, owners, researchers and consultants. The project combines analysis, field testing, dynamometer testing, condition monitoring, and the development and population of a gearbox failure database. At the core of the project are two 750kW gearboxes that have been redesigned and rebuilt so that they are representative of the multi-megawatt gearbox topology currently used in the industry. These gearboxes are heavily instrumented and are tested in the field and on the dynamometer. This report discusses the bearing calibrations of the gearboxes.

  7. Quantum reading capacity

    Science.gov (United States)

    Pirandola, Stefano; Lupo, Cosmo; Giovannetti, Vittorio; Mancini, Stefano; Braunstein, Samuel L.

    2011-11-01

    The readout of a classical memory can be modelled as a problem of quantum channel discrimination, where a decoder retrieves information by distinguishing the different quantum channels encoded in each cell of the memory (Pirandola 2011 Phys. Rev. Lett. 106 090504). In the case of optical memories, such as CDs and DVDs, this discrimination involves lossy bosonic channels and can be remarkably boosted by the use of nonclassical light (quantum reading). Here we generalize these concepts by extending the model of memory from single-cell to multi-cell encoding. In general, information is stored in a block of cells by using a channel-codeword, i.e. a sequence of channels chosen according to a classical code. Correspondingly, the readout of data is realized by a process of ‘parallel’ channel discrimination, where the entire block of cells is probed simultaneously and decoded via an optimal collective measurement. In the limit of a large block we define the quantum reading capacity of the memory, quantifying the maximum number of readable bits per cell. This notion of capacity is nontrivial when we suitably constrain the physical resources of the decoder. For optical memories (encoding bosonic channels), such a constraint is energetic and corresponds to fixing the mean total number of photons per cell. In this case, we are able to prove a separation between the quantum reading capacity and the maximum information rate achievable by classical transmitters, i.e. arbitrary classical mixtures of coherent states. In fact, we can easily construct nonclassical transmitters that are able to outperform any classical transmitter, thus showing that the advantages of quantum reading persist in the optimal multi-cell scenario.

  8. Enhancing human capacities

    CERN Document Server

    Savulescu, Julian; Kahane, Guy

    2011-01-01

    Enhancing Human Capacities is the first to review the very latest scientific developments in human enhancement. It is unique in its examination of the ethical and policy implications of these technologies from a broad range of perspectives. Presents a rich range of perspectives on enhancement from world leading ethicists and scientists from Europe and North America The most comprehensive volume yet on the science and ethics of human enhancement Unique in providing a detailed overview of current and expected scientific advances in this area Discusses both general conceptual and ethical issues

  9. Evaluation of bearing configurations using the single bearing tester in liquid nitrogen

    Science.gov (United States)

    Jett, T.; Hall, P.; Thom, R.

    1991-01-01

    Various bearing configurations were tested using the Marshall Space Flight Center single bearing tester with LN2 as the cryogenic coolant. The baseline was one Rocketdyne phase one high pressure oxidizer turbopump (HPOTP) pump end 45-mm bore bearing. The bearing configurations that were tested included a Salox/M cage configuration, a silicon nitride ball configuration, an elongated cage configuration, and a Bray 601 grease configuration.

  10. Rotor-Bearing Dynamics Technology Design Guide. Part 4. Cylindrical Roller Bearings

    Science.gov (United States)

    1979-12-01

    ýbluck ,,lb.,mb i Tapered Roller Bearings Roller Beating Stiffness Tapered Roller Bearing Stiffness Turbine Bearings VRoller Bearings Rotordynamics ...input for rotordynamic response programs. The complete stiffness matrix is calculated including centrifugal effects. Considerations such as elastohydro...those parts directly connected with preparation of input for the rotordynamic response programs (Part 1(5) of the revised series) were retained. The

  11. Non-Newtonian Effects of Second-Order Fluids on the Hydrodynamic Lubrication of Inclined Slider Bearings.

    Science.gov (United States)

    Apparao, Siddangouda; Biradar, Trimbak Vaijanath; Naduvinamani, Neminath Bhujappa

    2014-01-01

    Theoretical study of non-Newtonian effects of second-order fluids on the performance characteristics of inclined slider bearings is presented. An approximate method is used for the solution of the highly nonlinear momentum equations for the second-order fluids. The closed form expressions for the fluid film pressure, load carrying capacity, frictional force, coefficient of friction, and centre of pressure are obtained. The non-Newtonian second order fluid model increases the film pressure, load carrying capacity, and frictional force whereas the center of pressure slightly shifts towards exit region. Further, the frictional coefficient decreases with an increase in the bearing velocity as expected for an ideal fluid.

  12. Practice and design of the self-purification system for heavy metals-bearing contaminants

    Institute of Scientific and Technical Information of China (English)

    Qian Guangren

    2008-01-01

    Many minerals in nature have self-purification capacity to hold and stabilize deleterious contaminants into their lattice structures,which can be used for treatment of heavy metals-bearing contaminants.Hydrotalcite Layer Double Hy-droxide(LDH),tobermorite Calcium Silicate Hydrate(CSH)and apatite are ubiquitous minerals in nature,having higher geochemical stability and potential for binding and stabilizing heavy metals.Based on the elucidation of crystal structure property and self-purification principles of the three minerals above,this article discussed how to design the self-purification system of heavy metal-bearing contaminants.

  13. Mechanical Parameters of the Squeeze Film Curvilinear Bearing Lubricated with a Prandtl Fluid

    Science.gov (United States)

    Walicka, A.; Walicki, E.

    2016-12-01

    Based upon a Prandtl fluid flow model, a curvilinear squeeze film bearing is considered. The equations of motion are given in a specific coordinate system. After general considerations on the Prandtl fluid flow these equations are used to derive the Reynolds equation. The solution of this equation is obtained by a method of successive approximation. As a result one obtains formulae expressing the pressure distribution and load-carrying capacity. The numerical examples of the Prandtl fluid flow in gaps of two simple bearings are presented.

  14. ANALYSIS ON MOTION STABILITY OF A HIGH-SPEED ROTOR-BEARING SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Zhang Junhong; Sun Shaojun

    2005-01-01

    A non-linear dynamic model of one type of high-speed rotor system with gas supporting system is set up. The laws between the capacity force and the parameters of bearing, the static equilibrium position and rotating speed are studied on the basis of above model. Then, the failure rotating speed is given in the working state, and the relation between the minimum failure rotating speed and clearance of bearing is also studied. At last, the stability and failure condition are discussed in different working conditions.

  15. An Analytical Approach for Analysis of Slider Bearings with Non-Newtonian Lubricants

    Directory of Open Access Journals (Sweden)

    Li-Ming Chu

    2014-01-01

    Full Text Available In this study, a regular perturbation technique is utilized to derive the modified Reynolds equation which is applicable to power-law lubricant. The performance of slider bearings including pressure distributions, velocity distributions, film thickness, load capacity, flow rate, shear force, and friction coefficient is also derived analytically for various ξ, flow indices (n, and outlet film thicknesses (H0. These analytical solutions are clear to find the effects of the operation parameters rather than numerical methods. It can be simply and fast used for engineers. Subsequently, these proposed analytical solutions are used to analyze the lubrication performance of slider bearing with the power-law fluids.

  16. State Space Formulation of Nonlinear Vibration Responses Collected from a Dynamic Rotor-Bearing System: An Extension of Bearing Diagnostics to Bearing Prognostics

    Directory of Open Access Journals (Sweden)

    Peter W. Tse

    2017-02-01

    Full Text Available Bearings are widely used in various industries to support rotating shafts. Their failures accelerate failures of other adjacent components and may cause unexpected machine breakdowns. In recent years, nonlinear vibration responses collected from a dynamic rotor-bearing system have been widely analyzed for bearing diagnostics. Numerous methods have been proposed to identify different bearing faults. However, these methods are unable to predict the future health conditions of bearings. To extend bearing diagnostics to bearing prognostics, this paper reports the design of a state space formulation of nonlinear vibration responses collected from a dynamic rotor-bearing system in order to intelligently predict bearing remaining useful life (RUL. Firstly, analyses of nonlinear vibration responses were conducted to construct a bearing health indicator (BHI so as to assess the current bearing health condition. Secondly, a state space model of the BHI was developed to mathematically track the health evolution of the BHI. Thirdly, unscented particle filtering was used to predict bearing RUL. Lastly, a new bearing acceleration life testing setup was designed to collect natural bearing degradation data, which were used to validate the effectiveness of the proposed bearing prognostic method. Results show that the prediction accuracy of the proposed bearing prognostic method is promising and the proposed bearing prognostic method is able to reflect future bearing health conditions.

  17. Integration of Shape Memory Alloys into Low-Damped Rotor-Bearing Systems

    DEFF Research Database (Denmark)

    Enemark, Søren

    2015-01-01

    Rotor-bearing systems are key components in a variety of industrial equipment, as turbines, compressors, pumps etc. They are often subjected to strict requirements with respect to cost of energy and stability. Solutions that meet the requirements often involve: low friction between rotor and bear......Rotor-bearing systems are key components in a variety of industrial equipment, as turbines, compressors, pumps etc. They are often subjected to strict requirements with respect to cost of energy and stability. Solutions that meet the requirements often involve: low friction between rotor...... and bearing, high damping of lateral vibrations and high load-carrying capacity. Gas bearings and passive magnetic bearings are examples with very low friction. However, both examples also have a drawback with respect to very low damping and therefore prone to instability. To increase damping it is relevant...... to use passive adaptive control through smart materials. Shape Memory Alloys (SMAs) are interesting candidates in that relation, because of their highly temperature sensitive stiffness and mechanical hysteresis, which can be used for damping purposes. The thesis focuses on three main aspects related...

  18. Detection and Quantization of Bearing Fault in Direct Drive Wind Turbine via Comparative Analysis

    Directory of Open Access Journals (Sweden)

    Wei Teng

    2016-01-01

    Full Text Available Bearing fault is usually buried by intensive noise because of the low speed and heavy load in direct drive wind turbine (DDWT. Furthermore, varying wind speed and alternating loads make it difficult to quantize bearing fault feature that indicates the degree of deterioration. This paper presents the application of multiscale enveloping spectrogram (MuSEnS and cepstrum to detect and quantize bearing fault in DDWT. MuSEnS can manifest fault modulation information adaptively based on the capacity of complex wavelet transform, which enables the weak bearing fault in DDWT to be detected. Cepstrum can calculate the average interval of periodic components in frequency domain and is suitable for quantizing bearing fault feature under varying operation conditions due to the logarithm weight on the power spectrum. Through comparing a faulty DDWT with a normal one, the bearing fault feature is evidenced and the quantization index is calculated, which show a good application prospect for condition monitoring and fault diagnosis in real DDWT.

  19. Performance of a continuous flow ventricular assist device: magnetic bearing design, construction, and testing.

    Science.gov (United States)

    Allaire, P; Hilton, E; Baloh, M; Maslen, E; Bearnson, G; Noh, D; Khanwilkar, P; Olsen, D

    1998-06-01

    A new centrifugal continuous flow ventricular assist device, the CFVAD III, which is fully magnetic bearing suspended, has been developed. It has only one moving part (the impeller), has no contact (magnetic suspension), is compact, and has minimal heating. A centrifugal impeller of 2 inch outer diameter is driven by a permanent magnet brushless DC motor. This paper discusses the design, construction, testing, and performance of the magnetic bearings in the unit. The magnetic suspension consists of an inlet side magnetic bearing and an outlet side magnetic bearing, each divided into 8 pole segments to control axial and radial displacements as well as angular displacements. The magnetic actuators are composed of several different materials to minimize size and weight while having sufficient load capacity to support the forces on the impeller. Flux levels in the range of 0.1 T are employed in the magnetic bearings. Self sensing electronic circuits (without physical sensors) are employed to determine the impellar position and provide the feedback control signal needed for the magnetic bearing control loops. The sensors provide position sensitivity of approximately 0.025 mm. A decentralized 5 axis controller has been developed using modal control techniques. Proportional integral derivative controls are used for each axis to levitate the magnetically supported impeller.

  20. Hydrodynamic and hydrostatic modelling of hydraulic journal bearings considering small displacement condition

    Science.gov (United States)

    Chen, Chi-Yin; Chuang, Jen-Chen; Tu, Jia-Ying

    2016-09-01

    This paper proposes modified coefficients for the dynamic model of hydraulic journal bearing system that integrates the hydrodynamic and hydrostatic properties. In recent years, design of hydraulic bearing for machine tool attracts worldwide attention, because hydraulic bearings are able to provide higher capacity and accuracy with lower friction, compared to conventional bearing systems. In order to achieve active control of the flow pressure and enhance the operation accuracy, the dynamic model of hydraulic bearings need to be developed. Modified coefficients of hydrostatic stiffness, hydrodynamic stiffness, and squeeze damping of the dynamic model are presented in this work, which are derived referring to small displacement analysis from literature. The proposed modified coefficients and model, which consider the pressure variations, relevant geometry size, and fluid properties of the journal bearings, are able to characterise the hydrodynamic and hydrostatic properties with better precision, thus offering the following pragmatic contribution: (1) on-line prediction of the eccentricity and the position of the shaft in the face of external force that results in vibration; (2) development of active control system to regulate the supply flow pressure and to minimize the eccentricity of the shaft. Theoretical derivation and simulation results with different vibration cases are discussed to verify the proposed techniques.

  1. Deficiency of employability capacity

    Directory of Open Access Journals (Sweden)

    Pelse I.

    2012-10-01

    Full Text Available Young unemployed people have comprised one of the significantly largest groups of the unemployed people in Latvia in recent years. One of the reasons why young people have difficulty integrating into the labour market is the “expectation gap” that exists in the relations between employers and the new generation of workers. Employers focus on capacity-building for employability such individual factors as strength, patience, self-discipline, self-reliance, self-motivation, etc., which having a nature of habit and are developed in a long-term work socialization process, which begins even before the formal education and will continue throughout the life cycle. However, when the socialization is lost, these habits are depreciated faster than they can be restored. Currently a new generation is entering the labour market, which is missing the succession of work socialization. Factors, such as rising unemployment and poverty in the background over the past twenty years in Latvia have created a very unfavourable employability background of “personal circumstances” and “external factors”, which seriously have impaired formation of the skills and attitudes in a real work environment. The study reveals another paradox – the paradox of poverty. Common sense would want to argue that poverty can be overcome by the job. However, the real state of affairs shows that unfavourable coincidence of the individual, personal circumstances and external factors leads to deficit of employability capacity and possibility of marked social and employment deprivation.

  2. Heat Capacity in Proteins

    Science.gov (United States)

    Prabhu, Ninad V.; Sharp, Kim A.

    2005-05-01

    Heat capacity (Cp) is one of several major thermodynamic quantities commonly measured in proteins. With more than half a dozen definitions, it is the hardest of these quantities to understand in physical terms, but the richest in insight. There are many ramifications of observed Cp changes: The sign distinguishes apolar from polar solvation. It imparts a temperature (T) dependence to entropy and enthalpy that may change their signs and which of them dominate. Protein unfolding usually has a positive ΔCp, producing a maximum in stability and sometimes cold denaturation. There are two heat capacity contributions, from hydration and protein-protein interactions; which dominates in folding and binding is an open question. Theoretical work to date has dealt mostly with the hydration term and can account, at least semiquantitatively, for the major Cp-related features: the positive and negative Cp of hydration for apolar and polar groups, respectively; the convergence of apolar group hydration entropy at T ≈ 112°C; the decrease in apolar hydration Cp with increasing T; and the T-maximum in protein stability and cold denaturation.

  3. Precision instrumentation for rolling element bearing characterization

    Science.gov (United States)

    Marsh, Eric R.; Vigliano, Vincent C.; Weiss, Jeffrey R.; Moerlein, Alex W.; Vallance, R. Ryan

    2007-03-01

    This article describes an instrument to measure the error motion of rolling element bearings. This challenge is met by simultaneously satisfying four requirements. First, an axial preload must be applied to seat the rolling elements in the bearing races. Second, one of the races must spin under the influence of an applied torque. Third, rotation of the remaining race must be prevented in a way that leaves the radial, axial/face, and tilt displacements free to move. Finally, the bearing must be fixtured and measured without introducing off-axis loading or other distorting influences. In the design presented here, an air bearing reference spindle with error motion of less than 10 nm rotates the inner race of the bearing under test. Noninfluencing couplings are used to prevent rotation of the bearing outer race and apply an axial preload without distorting the bearing or influencing the measurement. Capacitive displacement sensors with 2 nm resolution target the nonrotating outer race. The error motion measurement repeatability is shown to be less than 25 nm. The article closes with a discussion of how the instrument may be used to gather data with sufficient resolution to accurately estimate the contact angle of deep groove ball bearings.

  4. Can polar bear hairs absorb environmental energy?

    OpenAIRE

    He Ji-Huan; Wang Qing-Li; Sun Jie

    2011-01-01

    A polar bear (Ursus maritimus) has superior ability to survive in harsh Arctic regions, why does the animal have such an excellent thermal protection? The present paper finds that the unique labyrinth cavity structure of the polar bear hair plays an important role. The hair can not only prevent body temperature loss but can also absorb energy from the environment.

  5. Can polar bear hairs absorb environmental energy?

    Directory of Open Access Journals (Sweden)

    He Ji-Huan

    2011-01-01

    Full Text Available A polar bear (Ursus maritimus has superior ability to survive in harsh Arctic regions, why does the animal have such an excellent thermal protection? The present paper finds that the unique labyrinth cavity structure of the polar bear hair plays an important role. The hair can not only prevent body temperature loss but can also absorb energy from the environment.

  6. Movie Director Bags a Silver Bear

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Chinese director and film writer Wang Xiaoshuai has walked away with the Silver Bear award at the 58th Berlin International Film Festival for best script of Zuo You, or In Love We Trust. Back in 2001, Wang won his first Silver Bear award for directing Beijing

  7. Big Change in PF Capacity

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Paraformaldehyde (PF) production in China has grown to a considerable scale today. The total capacity was around 90 thousand t/a in 2006. Since 2007, the production capacity of PF has increased drastically.

  8. Workshop on moisture buffer capacity

    DEFF Research Database (Denmark)

    2003-01-01

    Summary report of a Nordtest workshop on moisture buffer capacity held at Copenhagen August 21-22 2003......Summary report of a Nordtest workshop on moisture buffer capacity held at Copenhagen August 21-22 2003...

  9. Shaft Center Orbit in Dynamically Loaded Bearings

    DEFF Research Database (Denmark)

    Klit, Peder

    2005-01-01

    The aim of this work is to demonstrate how to utilize the bearings damping coe±cients to estimate the orbit for a dynamically loaded journal bearing. The classical method for this analysis was developed by Booker in 1965 [1]and described further in 1972 [2]. Several authors have re¯ned this method...... seventies Jorgen W. Lund pointed out in lecture notes that the dynamic damping coe±cients of the bearing could be used to ¯nd the shaft orbit for dynamically loaded bearings. For simplicity the "Short-Width-Journal-Bearing Theory" is used as a basis for ¯nding the damping coe±cients in this work...

  10. Trends in Controllable Oil Film Bearings

    DEFF Research Database (Denmark)

    Santos, Ilmar

    2011-01-01

    This work gives an overview about the theoretical and experimental achievements of mechatronics applied to oil film bearings, with the aim of: controlling the lateral vibration of flexible rotating shafts; modifying bearing dynamic characteristics, as stiffness and damping properties; increasing...... the rotational speed ranges by improving damping and eliminating instability problems, for example, by compensating cross-coupling destabilizing effects; reducing startup torque and energy dissipation in bearings; compensating thermal effects. It is shown that such controllable bearings can act as "smart......" components and be applied to rotating machines with the goal of avoiding unexpected stops of plants, performing rotordynamic tests and identifying model parameters "on site". Emphasis is given to the controllable lubrication (active lubrication) applied to different types of oil film bearings, i...

  11. 径向磁轴承的力学特性%Mechanical Characteristics of Radial Magnetic Bearing

    Institute of Scientific and Technical Information of China (English)

    张钢; 虞烈; 谢友柏

    2001-01-01

    This paper is based on the example of a radial magnetic bearing possessed of eight-pole, and derives the calculation formulas of static and dynamic mechanical characteristics of the bearing, in which the shape and curvature of surface, eccentricity and tilt of the journal are taken into account. Variations of the static and dynamic characteristics of the radial magnetic bearing versus static tilt parameters of journal are discussed. The outcomes show that the static tilt of the journal has influence on the mechanical characteristics of radial magnetic bearing, and change the static load capacity between two radial magnetic bearings and exert coupling effect between them. To study the dynamics of a practical rotor-magnetic bearing system, at least six stiffness coefficients in each radial magnetic bearing must be considered in ideal case, and twelve stiffness coefficients must be considered in general case of tilting journal. Such a find can be used for the coupled electromechanical dynamics analysis of rotor system equipped with magnetic bearings.

  12. 径向磁轴承的力学特性%Mechanical Characteristics of Radial Magnetic Bearing

    Institute of Scientific and Technical Information of China (English)

    张钢; 虞烈; 谢友柏

    2000-01-01

    This paper is based on the example of a radial magnetic bearing possessed of eight-pole, and derives the calculation formulas of static and dynamic mechanical characteristics of the bearing, in which the shape and curvature of surface, eccentricity and tilt of the journal are taken into account. Variations of the static and dynamic characteristics of the radial magnetic bearing versus static tilt parameters of journal are discussed. The outcomes show that the static tilt of the journal has influence on the mechanical characteristics of radial magnetic bearing, and change the static load capacity between two radial magnetic bearings and exert coupling effect between them. To study the dynamics of a practical rotor-magnetic bearing system, at least six stiffness coefficients in each radial magnetic bearing must be considered in ideal case, and twelve stiffness coefficients must be considered in general case of tilting journal. Such a find can be used for the coupled electromechanical dynamics analysis of rotor system equipped with magnetic bearings.

  13. Geology and geomorphology of Bear Lake Valley and upper Bear River, Utah and Idaho

    Science.gov (United States)

    Reheis, M.C.; Laabs, B.J.C.; Kaufman, D.S.

    2009-01-01

    Bear Lake, on the Idaho-Utah border, lies in a fault-bounded valley through which the Bear River flows en route to the Great Salt Lake. Surficial deposits in the Bear Lake drainage basin provide a geologic context for interpretation of cores from Bear Lake deposits. In addition to groundwater discharge, Bear Lake received water and sediment from its own small drainage basin and sometimes from the Bear River and its glaciated headwaters. The lake basin interacts with the river in complex ways that are modulated by climatically induced lake-level changes, by the distribution of active Quaternary faults, and by the migration of the river across its fluvial fan north of the present lake. The upper Bear River flows northward for ???150 km from its headwaters in the northwestern Uinta Mountains, generally following the strike of regional Laramide and late Cenozoic structures. These structures likely also control the flow paths of groundwater that feeds Bear Lake, and groundwater-fed streams are the largest source of water when the lake is isolated from the Bear River. The present configuration of the Bear River with respect to Bear Lake Valley may not have been established until the late Pliocene. The absence of Uinta Range-derived quartzites in fluvial gravel on the crest of the Bear Lake Plateau east of Bear Lake suggests that the present headwaters were not part of the drainage basin in the late Tertiary. Newly mapped glacial deposits in the Bear River Range west of Bear Lake indicate several advances of valley glaciers that were probably coeval with glaciations in the Uinta Mountains. Much of the meltwater from these glaciers may have reached Bear Lake via groundwater pathways through infiltration in the karst terrain of the Bear River Range. At times during the Pleistocene, the Bear River flowed into Bear Lake and water level rose to the valley threshold at Nounan narrows. This threshold has been modified by aggradation, downcutting, and tectonics. Maximum lake

  14. Landfill Construction and Capacity Expansion

    NARCIS (Netherlands)

    Andre, F.J.; Cerda, E.

    2003-01-01

    We study the optimal capacity and lifetime of landfills taking into account their sequential nature.Such an optimal capacity is characterized by the so-called Optimal Capacity Condition.Particular versions of this condition are obtained for two alternative settings: first, if all the landfills are t

  15. Random Access Transport Capacity

    CERN Document Server

    Andrews, Jeffrey G; Kountouris, Marios; Haenggi, Martin

    2009-01-01

    We develop a new metric for quantifying end-to-end throughput in multihop wireless networks, which we term random access transport capacity, since the interference model presumes uncoordinated transmissions. The metric quantifies the average maximum rate of successful end-to-end transmissions, multiplied by the communication distance, and normalized by the network area. We show that a simple upper bound on this quantity is computable in closed-form in terms of key network parameters when the number of retransmissions is not restricted and the hops are assumed to be equally spaced on a line between the source and destination. We also derive the optimum number of hops and optimal per hop success probability and show that our result follows the well-known square root scaling law while providing exact expressions for the preconstants as well. Numerical results demonstrate that the upper bound is accurate for the purpose of determining the optimal hop count and success (or outage) probability.

  16. Power optimization for maximum channel capacity in MIMO relay system

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Introducing multiple-input multiple-output (MIMO) relay channel could offer significant capacity gain.And it is of great importance to develop effective power allocation strategies to achieve power efficiency and improve channel capacity in amplify-and-forward relay system.This article investigates a two-hop MIMO relay system with multiple antennas in relay node (RN) and receiver (RX).Maximizing capacity with antenna selection (MCAS) and maximizing capacity with eigen-decomposition (MCED) schemes are proposed to efficiently allocate power among antennas in RN under first and second hop limited scenarios.The analysis and simulation results show that both MCED and MCAS can improve the channel capacity compared with uniform power allocation (UPA) scheme in most of the studied areas.The MCAS bears comparison with MCED with an acceptable capacity loss, but lowers the complexity by saving channel state information (CSI) feedback to the transmitter (TX).Moreover, when the RN is close to RX, the performance of UPA is also close to the upper bound as the performance of first hop is limited.

  17. THE STRUCTURAL ANALYSIS OF STEEL SILOS WITH CYLINDRICAL-WALL BEARING AND PROFILE-STEEL BEARING

    Directory of Open Access Journals (Sweden)

    Zhengjun Tang

    2015-04-01

    Full Text Available The silos are widely used in bulk material in many fields such as agriculture, mining, chemical, electric power storage, etc. Thin metal cylindrical silo shells are vulnerable to buckling failure caused by the compressive wall friction force. In this paper, the structural analysis of two types of steel silo with cylindrical-wall bearing and profile-steel bearing is implemented by Abaqus finite element analysis. The results indicate that under the same loading conditions, steel silos with profile-steel bearing and cylindrical-Wall bearing have similar values in Mises stress, but the steel silo with profile-steel bearing has a smaller radial displacement and a better capability of buckling resistance. Meanwhile, the total steel volumes reduced 8.0% comparing to the steel silo with cylindrical-wall bearing. Therefore, steel soil with profile-steel bearing not only has a less steel volumes but also a good stability.

  18. Radiation tolerance in water bears.

    Science.gov (United States)

    Horikawa, D. D.; Sakashita, T.; Katagiri, C.; Watanabe, M.; Nakahara, Y.; Okuda, T.; Hamada, N.; Wada, S.; Funayama, T.; Kobayashi, Y.

    Tardigrades water bears are tiny invertebrates forming a phylum and inhabit various environments on the earth Terrestrial tardigrades enter a form called as anhydrobiosis when the surrounding water disappears Anhyydrobiosis is defined as an ametabolic dry state and followed by recovering their activity when rehydrated Anhydrobiotic tardigrades show incredible tolerance to a variety of extreme environmental conditions such as temperatures -273 r C to 151 r C vacuum high pressure 600 MPa and chemicals that include alcohols and methyl bromide In these views there have been some discussions about their potential for surviving outer space In the present study we demonstrated the survival limit not merely against gamma-rays but against heavy ions in the tardigrade Milnesium tardigradum in order to evaluate the effects of radiations on them The animals were exposure to 500 to 7000 Gy of gamma-rays or 500 to 8000 Gy of heavy ions 4 He in their hydrated or anhydrobiotic state The results showed that both of hydrated and anhydrobiotic animals have high radio-tolerance median lethal dose LD50 48 h of gamma-rays or heavy ions in M tardigradum was more than 4000 Gy indicating that this species is categorized into the most radio-tolerant animals We suggest that tardigrades will be suitable model animals for extremophilic multicellular organisms and may provide a survival strategy in extraterrestrial environments

  19. Conservation Strategy for Brown Bear and Its Habitat in Nepal

    Directory of Open Access Journals (Sweden)

    Achyut Aryal

    2012-08-01

    Full Text Available The Himalaya region of Nepal encompasses significant habitats for several endangered species, among them the brown bear (Ursus arctos pruinosus. However, owing to the remoteness of the region and a dearth of research, knowledge on the conservation status, habitat and population size of this species is lacking. Our aim in this paper is to report a habitat survey designed to assess the distribution and habitat characteristics of the brown bear in the Nepalese Himalaya, and to summarize a conservation action plan for the species devised at a pair of recent workshops held in Nepal. Results of our survey showed that brown bear were potentially distributed between 3800 m and 5500 m in the high mountainous region of Nepal, across an area of 4037 km2 between the eastern border of Shey Phoksundo National Park (SPNP and the Manasalu Conservation Area (MCA. Of that area, 2066 km2 lie inside the protected area (350 km2 in the MCA; 1716 km2 in the Annapurna Conservation Area and 48% (1917 km2 lies outside the protected area in the Dolpa district. Furthermore, 37% of brown bear habitat also forms a potential habitat for blue sheep (or bharal, Pseudois nayaur, and 17% of these habitats is used by livestock, suggesting a significant potential for resource competition. Several plant species continue to be uprooted by local people for fuel wood. Based on the results of our field survey combined with consultations with local communities and scientists, we propose that government and non-government organizations should implement a three-stage program of conservation activities for the brown bear. This program should: (a Detail research activities in and outside the protected area of Nepal; (b support livelihood and conservation awareness at local and national levels; and (c strengthen local capacity and reduce human-wildlife conflict in the region.

  20. Capacity Utilization in European Railways

    DEFF Research Database (Denmark)

    Khadem Sameni, Melody; Landex, Alex

    2013-01-01

    At the strategic level, railways currently use different indices to estimate how ‘value’ is generated by using railway capacity. However, railway capacity is a multidisciplinary area, and attempts to develop various indices cannot provide a holistic measure of operational efficiency. European...... railways are facing a capacity challenge which is caused by passenger and freight demand exceeding the track capacity supply. In the absence of a comprehensive railway capacity manual, methodologies are needed to assess how well railways use their track capacity. This paper presents a novel...... and unprecedented approach for this aim. Relative operational efficiency of 24 European railways in capacity utilization is studied for the first time by data envelopment analysis (DEA). It deviates from previous applications of DEA in the railway industry that are conducted to analyze cost efficiency of railways...

  1. Bearing Capacity of Circular Footings on a Hoek–Brown Material

    DEFF Research Database (Denmark)

    Clausen, Johan

    2013-01-01

    spatial development processes. The reasoning behind this argument stems from the case of Denmark, where a structural reform that changed the country’s geographies of inter-governmental arrangements significantly transformed the configuration and functioning of the national spatial planning system. Once...... designed to pursue ‘equal development’ as a result of a structural reform of a different nature implemented during the 1970s, Danish planning as a whole and national and regional planning policies, in particular, currently seem to have become less ‘spatial’ in the sense that the latter only tend to exhibit...... and integration of sectors and policies within and across different levels. Based on an analysis regarding the evolution of planning policies and an examination of the current governance landscape that influences planning practice at national and regional levels, the paper attempts to generate an understanding...

  2. A numerical assessment of the load bearing capacity of externally pressurized moderately thick tubes

    Energy Technology Data Exchange (ETDEWEB)

    Corradi, Leone [Politecnico di Milano - Department of Energy, Enrico Fermi Center for Nuclear Studies (CeSNEF), via Ponzio 34/3 - 20133 Milano (Italy)], E-mail: leone.corradi@polimi.it; Di Marcello, Valentino; Luzzi, Lelio; Trudi, Fulvio [Politecnico di Milano - Department of Energy, Enrico Fermi Center for Nuclear Studies (CeSNEF), via Ponzio 34/3 - 20133 Milano (Italy)

    2009-08-15

    The collapse behavior of cylindrical shells pressurized from outside is examined. Attention is focused on tubes of moderate thickness, as required by very deep water pipelines or some innovative nuclear power plant proposals. Their collapse is expected to be dominated by yielding but, because of the decreasing nature of the post-collapse evolution, interaction with instability is likely to be significant enough to demand consideration. At present, no quantitative assessment of such effect is available, because little study has been devoted to tubes in this thickness range. Plasticity-instability interaction is activated by imperfections and to assess their influence on a systematic numerical study is undertaken. Computations produce a meaningful measure of the collapse pressure and it is proposed that the allowable pressure be determined on its basis, by introducing a suitable safety factor. This is chosen so that results reproduce those provided by presently accepted procedures in the well explored and reliable range of medium-thin tubes. When the same factor is applied to thicker tubes, the resulting allowable pressure is significantly higher than the values suggested by codes, which apparently react to the present lack of knowledge by assuming an extremely conservative attitude.

  3. Why a mosquito leg possesses superior load-bearing capacity on water: Experimentals

    Science.gov (United States)

    Kong, Xiang-Qing; Liu, Jian-Lin; Wu, Cheng-Wei

    2016-04-01

    Mosquitoes possess the striking ability to walk on water because each of their legs has a huge water supporting force (WSF) that is 23 times their body weight. Aiming at a full understanding of the origins of this extremely large force, in this study, we concentrate on two aspects of it: the intrinsic properties of the leg surface and the active control of the initial stepping angle of the whole leg. Using a measurement system that we developed ourselves, the WSFs for the original leg samples are compared with those whose surface wax and microstructures have been removed and with those of a different stiffness. The results show that leg flexibility plays a dominant role over surface wax and microstructures on the leg surface in creating the supporting force. Moreover, we discuss the dependence relationship between the maximum WSF and the initial stepping angle, which indicates that the mosquito can regulate this angle to increase or decrease the WSF during landing or takeoff. These findings are helpful for uncovering the locomotion mechanism of aquatic insects and for providing inspiration for the design of microfluids, miniature boats, biomimetic robots, and microsensors.

  4. Effects of wheel damage on peat grasslands at low bearing capacity at high ditch levels

    NARCIS (Netherlands)

    Holshof, G.; Houwelingen, van K.M.

    2012-01-01

    From the 1960s onwards in the Netherlands, many relatively wet peat lands were deep(er) dewatered to a ditch water level of 50 to 60 cm below the surface to improve dairy agriculture. As a consequence of this deeper drainage, peat degradation took place due to mineralisation, resulting in a relative

  5. Analysis of Bearing Capacity of Suction Bucket Foundation Subjected to Horizontal and Moment Loadings

    OpenAIRE

    W.U. Ke; M.A. Mingyue

    2013-01-01

    The suction bucket foundation is not only supporting the vertical loading such as the sea platform and weight itself, but also subjecting to horizontal and moment loading due to wind and wave. The response of bucket foundation to combined Horizontal (H) and Moment (M) loading has been studied using 3D finite element analysis Then the proposed method is numerically implemented in the framework of the general-purpose FEM software ABAQUS. Relationship curve between the coefficient of ultimate be...

  6. Inertially stabilized line-of-sight control system using a magnetic bearing with vernier gimbaling capacity

    Science.gov (United States)

    Lin, Zhuchong; Liu, Kun

    2014-11-01

    Line of sight stabilization and control system is widely used in pointing and stabilizing the line of sight of optical sensors. Multi-axis gimbals configurations are commonly used for isolating disturbance from the angular motion of the base where the stabilization platform is mounted. However, in the case of large payload, nonlinear friction and the bandwidth limit of the servo loop can greatly diminish the performance of the whole system. Magnetic actuators, because of their high force per mass capability and non-friction characteristic, are promising means of achieving high-accuracy stabilization. Nevertheless, the gap between magnetic actuators and the payload is very small, which limits the slewing range of the line of sight as well as the angular motion range of the base that can be isolated. A novel two-stage stabilization configuration is developed, which combines multi-axis gimbals configuration and magnetic actuators as well as both of their advantages. At the first stage, a multi-axis gimbals configuration is adopted to isolate the large angular motion of the base while at the second stage magnetic actuators are utilized to perform high-accuracy stabilization. A so-called "stabilizing inside and tracking outside" scheme is carried out to perform two-stage stabilization control. The advantage of this configuration compared with conventional configuration is analyzed through analytical method. Finally, the effectiveness of the design is investigated through simulation studies.

  7. 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 ...

  8. Very High Load Capacity Air Bearing Spindle for Large Diamond Turning Machines Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Diamond turning is able to produce highly aspheric visible quality optics which can be easily aligned. Very large optical systems such as OWL and EUSO are impossible...

  9. Lateral Bearing Capacity of Single Connectors in Parallel Loaded Battens used for Truss Bracing

    DEFF Research Database (Denmark)

    Nielsen, Jacob

    In order to analyse the stiffness and the strength of joints used for battens in bracing of trusses 70 tests have been made. The joint was made by a single nail or screw located perpendicular to or at an angle to the grain direction. The single fastener joints did not fulfil the requirements for ...

  10. Grizzly bear diet shifting on reclaimed mines

    Directory of Open Access Journals (Sweden)

    Bogdan Cristescu

    2015-07-01

    Full Text Available Industrial developments and reclamation change habitat, possibly altering large carnivore food base. We monitored the diet of a low-density population of grizzly bears occupying a landscape with open-pit coal mines in Canada. During 2009–2010 we instrumented 10 bears with GPS radiocollars and compared their feeding on reclaimed coal mines and neighboring Rocky Mountains and their foothills. In addition, we compared our data with historical bear diet for the same population collected in 2001–2003, before extensive mine reclamation occurred. Diet on mines (n=331 scats was dominated by non-native forbs and graminoids, while diets in the Foothills and Mountains consisted primarily of ungulates and Hedysarum spp. roots respectively, showing diet shifting with availability. Field visitation of feeding sites (n=234 GPS relocation clusters also showed that ungulates were the main diet component in the Foothills, whereas on reclaimed mines bears were least carnivorous. These differences illustrate a shift to feeding on non-native forbs while comparisons with historical diet reveal emergence of elk as an important bear food. Food resources on reclaimed mines attract bears from wilderness areas and bears may be more adaptable to landscape change than previously thought. The grizzly bear’s ready use of mines cautions the universal view of this species as umbrella indicative of biodiversity.

  11. Genomic sequencing of Pleistocene cave bears

    Energy Technology Data Exchange (ETDEWEB)

    Noonan, James P.; Hofreiter, Michael; Smith, Doug; Priest, JamesR.; Rohland, Nadin; Rabeder, Gernot; Krause, Johannes; Detter, J. Chris; Paabo, Svante; Rubin, Edward M.

    2005-04-01

    Despite the information content of genomic DNA, ancient DNA studies to date have largely been limited to amplification of mitochondrial DNA due to technical hurdles such as contamination and degradation of ancient DNAs. In this study, we describe two metagenomic libraries constructed using unamplified DNA extracted from the bones of two 40,000-year-old extinct cave bears. Analysis of {approx}1 Mb of sequence from each library showed that, despite significant microbial contamination, 5.8 percent and 1.1 percent of clones in the libraries contain cave bear inserts, yielding 26,861 bp of cave bear genome sequence. Alignment of this sequence to the dog genome, the closest sequenced genome to cave bear in terms of evolutionary distance, revealed roughly the expected ratio of cave bear exons, repeats and conserved noncoding sequences. Only 0.04 percent of all clones sequenced were derived from contamination with modern human DNA. Comparison of cave bear with orthologous sequences from several modern bear species revealed the evolutionary relationship of these lineages. Using the metagenomic approach described here, we have recovered substantial quantities of mammalian genomic sequence more than twice as old as any previously reported, establishing the feasibility of ancient DNA genomic sequencing programs.

  12. Space Telescope Fine Guidance Sensor Bearing Anomaly

    Science.gov (United States)

    Loewenthal, S.; Esper, J.; Pan, J.; Decker, J.

    1996-01-01

    Early in 1993, a servo motor within one of three Fine Guidance Sensors (FGS) aboard the Hubble Space Telescope (HST) reached stall torque levels on several occasions. Little time was left to plan replacement during the first servicing mission, scheduled at the end of '93. Accelerated bearing life tests confirmed that a small angle rocking motion, known as Coarse Track (CT), accelerated bearing degradation. Saturation torque levels were reached after approximately 20 million test cycles, similar to the flight bearings. Reduction in CT operation, implemented in flight software, extended FGS life well beyond the first servicing mission. However in recent years, bearing torques have resumed upward trends and together with a second, recent bearing torque anomaly has necessitated a scheduled FGS replacement during the upcoming second servicing mission in '97. The results from two series of life tests to quantify FGS bearing remaining life, discussion of bearing on-orbit performance, and future plans to service the FGS servos are presented in this paper.

  13. Genetics Home Reference: Beare-Stevenson cutis gyrata syndrome

    Science.gov (United States)

    ... Health Conditions Beare-Stevenson cutis gyrata syndrome Beare-Stevenson cutis gyrata syndrome Enable Javascript to view the ... Download PDF Open All Close All Description Beare-Stevenson cutis gyrata syndrome is a genetic disorder characterized ...

  14. Capacity building for HIA

    Directory of Open Access Journals (Sweden)

    Gabriel Gulis PhD

    2007-09-01

    Full Text Available

    Background: To integrate health impact assessment (HIA into existing decision-making processes requires not only methods and procedures but also well-trained experts, aware policy makers and appropriate institutions. Capacity building is the assistance which is provided to entities, which have a need to develop a certain skill or competence, or for general upgrading of performance ability. If a new technique is planned to be introduced there is a need for capacity building with no respect to levels (local, regional, national, international or sectors (health, environment, finance, social care, education, etc.. As such, HIA is a new technique for most of the new Member States and accession countries of the European Union.

    Methods: To equip individuals with the understanding and skills needed to launch a HIA or be aware of the availability of this methodology and to access information, knowledge and training, we focused on the organization of workshops in participating countries. The workshops served also as pilot events to test a “curriculum” for HIA; a set of basic topics and presentations had been developed to be tested during workshops. In spite of classical in-class workshops we aimed to organize e-learning events as a way to over come the “busyness” problem of decision makers.

    Results: Throughout March – October 2006 we organized and ran 7 workshops in Denmark, Turkey, Lithuania, Poland, Bulgaria, Slovak Republic and Hungary. Participants came from the public health sector (141, non-public health decision makers (113 and public health students (100. A concise curriculum was developed and tested during these workshops. Participants developed a basic understanding of HIA, skills to develop and use their own screening tools as well as scoping.Within the workshop in Denmark we tested an online, real-time Internet based training method; participants highly welcomed this

  15. Eastern slopes grizzly bear project : project update

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-01-01

    This report updates a study to examine the cumulative effects of human activities on the grizzly bears in the central Canadian Rockies. The project was initiated in 1994 to acquire accurate scientific information on the habitat and populations of grizzly bears in the area of the Banff National Park and Kananaskis Country. This area is probably the most heavily used and developed area where the grizzly still survives. The information gathered throughout the course of the study is used to better protect and manage the bears and other sensitive carnivores in the region. Using telemetry, researchers monitored 25 grizzly bears which were radio-collared in a 22,000 square-kilometer area in the upper Bow Valley drainage of the eastern Alberta slopes. The researchers worked with representatives from Husky Oil and Rigel Energy on the development of the Moose Mountain oil and gas field without adversely affecting the grizzly bear population. Information collected over eight years indicates that the grizzly bears have few and infrequent offspring. Using the information gathered thus far, the location of the Moose Mountain to Jumping Pound pipeline was carefully selected, since the bears suffer from high mortality, and the food and cover had already been compromised by the high number of roads, trails and other human activities in the area. The research concluded in November 2001 provides sufficient information to accurately asses the status of the grizzly bear population and habitat. The data will be analyzed and integrated in 2002 into models that reflect the variables affecting grizzly bears and a final report will be published.

  16. 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

    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...

  17. Titanium carbide coatings for aerospace ball bearings

    Science.gov (United States)

    Boving, Hans J.; Haenni, Werner; Hintermann, HANS-E.

    1988-01-01

    In conventional ball bearings, steel to steel contacts between the balls and the raceways are at the origin of microwelds which lead to material transfer, surface roughening, lubricant breakdown, and finally to a loss in the bearing performances. To minimize the microwelding tendencies of the contacting partners it is necessary to modify their surface materials; the solid to solid collisions themselves are difficult to avoid. The use of titanium carbide coated steel balls can bring spectacular improvements in the performances and lifetimes of both oil-grease lubricated and oil-grease free bearings in a series of severe applications.

  18. Hydrostatic, aerostatic and hybrid bearing design

    CERN Document Server

    Rowe, W Brian

    2012-01-01

    Solve your bearing design problems with step-by-step procedures and hard-won performance data from a leading expert and consultant Compiled for ease of use in practical design scenarios, Hydrostatic, Aerostatic and Hybrid Bearing Design provides the basic principles, design procedures and data you need to create the right bearing solution for your requirements. In this valuable reference and design companion, author and expert W. Brian Rowe shares the hard-won lessons and figures from a lifetime's research and consultancy experience. Coverage includes: Clear e

  19. Microeconomic analysis of military aircraft bearing restoration

    Science.gov (United States)

    Hein, G. F.

    1976-01-01

    The risk and cost of a bearing restoration by grinding program was analyzed. A microeconomic impact analysis was performed. The annual cost savings to U.S. Army aviation is approximately $950,000.00 for three engines and three transmissions. The capital value over an indefinite life is approximately ten million dollars. The annual cost savings for U.S. Air Force engines is approximately $313,000.00 with a capital value of approximately 3.1 million dollars. The program will result in the government obtaining bearings at lower costs at equivalent reliability. The bearing industry can recover lost profits during a period of reduced demand and higher costs.

  20. Active magnetic bearings applied to industrial compressors

    Science.gov (United States)

    Kirk, R. G.; Hustak, J. F.; Schoeneck, K. A.

    1993-01-01

    The design and shop test results are given for a high-speed eight-stage centrifugal compressor supported by active magnetic bearings. A brief summary of the basic operation of active magnetic bearings and the required rotor dynamics analysis are presented with specific attention given to design considerations for optimum rotor stability. The concerns for retrofits of magnetic bearings in existing machinery are discussed with supporting analysis of a four-stage centrifugal compressor. The current status of industrial machinery in North America using this new support system is presented and recommendations are given on design and analysis requirements for successful machinery operation of either retrofit or new design turbomachinery.

  1. Rotor Vibration Reduction via Active Hybrid Bearings

    DEFF Research Database (Denmark)

    Nicoletti, Rodrigo; Santos, Ilmar

    2002-01-01

    The use of fluid power to reduce and control rotor vibration in rotating machines is investigated. An active hybrid bearing is studied, whose main objective is to reduce wear and vibration between rotating and stationary machinery parts. By injecting pressurised oil into the oil film, through...... orifices machined in the bearing pads, one can alter the machine dynamic characteristics, thus enhancing its operational range. A mathematical model of the rotor-bearing system, as well as of the hydraulic system, is presented. Numerical results of the system frequency response show good agreement...

  2. On Controllable Elastohydrodynamic Fluid Film Bearings

    DEFF Research Database (Denmark)

    Haugaard, Martin Asger

    This thesis gives a theoretical description of the active tilting-pad journal bearing (ATPJB). It provides the qualified reader with the tools to model an ATPJB, while staying clear of pitfalls. The model is based on well known techniques and allows for local stability analyses, harmonic stationary...... are performed for a tilting-pad journal bearing (TPJB) and an ATPJB under static conditions, followed by a generalisation to dynamic conditions (transient as well as stationary harmonic). These analyses will be of interest to experimentalists, since they permit experiments performed on scaled down test rigs...... the addition of a control system may just as well harm rotor-bearing performance as improve it....

  3. Wireless Connectivity and Capacity

    CERN Document Server

    Halldorsson, Magnus M

    2011-01-01

    Given $n$ wireless transceivers located in a plane, a fundamental problem in wireless communications is to construct a strongly connected digraph on them such that the constituent links can be scheduled in fewest possible time slots, assuming the SINR model of interference. In this paper, we provide an algorithm that connects an arbitrary point set in $O(\\log n)$ slots, improving on the previous best bound of $O(\\log^2 n)$ due to Moscibroda. This is complemented with a super-constant lower bound on our approach to connectivity. An important feature is that the algorithms allow for bi-directional (half-duplex) communication. One implication of this result is an improved bound of $\\Omega(1/\\log n)$ on the worst-case capacity of wireless networks, matching the best bound known for the extensively studied average-case. We explore the utility of oblivious power assignments, and show that essentially all such assignments result in a worst case bound of $\\Omega(n)$ slots for connectivity. This rules out a recent cla...

  4. Quantum Reading Capacity

    CERN Document Server

    Pirandola, Stefano; Giovannetti, Vittorio; Mancini, Stefano; Braunstein, Samuel L

    2011-01-01

    The readout of a classical memory can be modelled as a problem of quantum channel discrimination, where a decoder retrieves information by distinguishing the different quantum channels encoded in each cell of the memory [S. Pirandola, Phys. Rev. Lett. 106, 090504 (2011)]. In the case of optical memories, such as CDs and DVDs, this discrimination involves lossy bosonic channels and can be remarkably boosted by the use of nonclassical light (quantum reading). Here we generalize these concepts by extending the model of memory from single-cell to multi-cell encoding. In general, information is stored in a block of cells by using a channel-codeword, i.e., a sequence of channels chosen according to a classical code. Correspondingly, the readout of data is realized by a process of "parallel" channel discrimination, where the entire block of cells is probed simultaneously and decoded via an optimal collective measurement. In the limit of an infinite block we define the quantum reading capacity of the memory, quantify...

  5. Integrated flexible capacity and inventory management under flexible capacity uncertainty

    OpenAIRE

    Paç, Mehmet Fazıl

    2006-01-01

    Cataloged from PDF version of article. In a manufacturing environment with volatile demand, inventory management can be coupled with dynamic capacity adjustments for handling the fluctuations more effectively. In this study we consider the integrated management of inventory and flexible capacity management under seasonal stochastic demand and uncertain labor supply. The capacity planning problem is investigated from the workforce planning perspective. We consider a manufactu...

  6. Temperature control of transfer roller's bearing based on finite element analysis

    Institute of Scientific and Technical Information of China (English)

    Peng ZHANG; Yourong LI; Han XIAO

    2009-01-01

    After a heat preservation cover is installed on the main rolling line, the heat dissipation environment of the transfer roller working on the heat preservation cover is changed. To ensure the normal production, a reasonable working jet capacity of the roller neck is derived. First, a globe model of the transfer roller is built for finite element analysis. Second, the sub-model of the fixed end bearing is built and the boundary condition of the sub-model is supplied by the results of the globe model. The analysis result of the sub-model shows that the temperature of the transfer roller bearing exceeds 85℃ a rolling periodicity later. With finite element analysis, the heat flux is obtained and the minimum working jet capacity is derived.

  7. Cavitation Estimates by Orbit Prediction of a Journal Bearing - Finite Element Modelling and Experimental Studies Cavitation Estimates by Orbit Prediction of a Journal Bearing - Finite Element Modelling and Experimental Studies

    DEFF Research Database (Denmark)

    Christiansen, Christian Kim; Klit, Peder; Walther, Jens Honore;

    2015-01-01

    influencing the load carrying capacity and ultimately the chances of fatal shaft-sleeve contact. By solving Reynolds equation numerically using finite elements and incorporating a cavitation algorithm, the dynamic coefficients can be used to establish the journal orbit for a given bearing and load pattern...

  8. Vibration Characteristics of Hydrodynamic Fluid Film Pocket Journal Bearings

    Directory of Open Access Journals (Sweden)

    N. S. Feng

    2010-01-01

    Full Text Available Theoretical analyses of hydrodynamic fluid film bearings with different bearing profiles rely on solutions of the Reynolds equation. This paper presents an approach used for analysing the so-called pocket bearings formed from a combination of offset circular bearing profiles. The results show that the variation of the dynamic bearing characteristics with different load inclinations for the pocket bearings is less than that for the elliptic bearing counterpart. It is shown that the natural frequencies as well as the critical speeds, and hence the vibrational behaviour, can also be significantly different for an industrial rotor supported by the different bearings.

  9. Flywheel Energy Storage System Suspended by Hybrid Magnetic Bearing

    Science.gov (United States)

    Owusu-Ansah, Prince; Hu, Yefa; Misbawu, Adam

    This work presents a prototype flywheel energy storage system (FESS) suspended by hybrid magnetic bearing (HMB) rotating at a speed of 20000rpm with a maximum storage power capacity of 30W with a maximum tip speed of 300m/s. The design presented is an improvement of most existing FESS, as the design incorporates a unique feature in that the upper and the lower rotor and stator core are tapered which enhances larger thrust and much lower radial force to be exerted on the system. Without any adverse effect being experienced by the model. The work also focuses on the description of developing a prototype FESS suspended by HMB using solid works as a basis of developing in the nearer future a more improved FESS suspended by HMB capable of injecting the ever increasing high energy demand situation in the 21st century and beyond.

  10. Development of superconducting magnetic bearing for flywheel energy storage system

    Science.gov (United States)

    Miyazaki, Yoshiki; Mizuno, Katsutoshi; Yamashita, Tomohisa; Ogata, Masafumi; Hasegawa, Hitoshi; Nagashima, Ken; Mukoyama, Shinichi; Matsuoka, Taro; Nakao, Kengo; Horiuch, Shinichi; Maeda, Tadakazu; Shimizu, Hideki

    2016-12-01

    We have been developing a superconducting magnetic bearing (SMB) that has high temperature superconducting (HTS) coils and bulks for a flywheel energy storage system (FESS) that have an output capability of 300 kW and a storage capacity of 100 kW h (Nagashima et al., 2008, Hasegawa et al., 2015) [1,2]. The world largest-class FESS with a SMB has been completed and test operation has started. A CFRP flywheel rotor that had a diameter of 2 m and weight of 4000 kg had a capability to be rotated at a maximum speed of 6000 min-1. The SMB using superconducting material both for its rotor and stator is capable of supporting the flywheel that had the heavy weight and the high seed rotation mentioned above. This paper describes the design of the SMB and results of the cooling test of the SMB.

  11. Test equipment for a flywheel energy storage system using a magnetic bearing composed of superconducting coils and superconducting bulks

    Science.gov (United States)

    Ogata, M.; Matsue, H.; Yamashita, T.; Hasegawa, H.; Nagashima, K.; Maeda, T.; Matsuoka, T.; Mukoyama, S.; Shimizu, H.; Horiuchi, S.

    2016-05-01

    Energy storage systems are necessary for renewable energy sources such as solar power in order to stabilize their output power, which fluctuates widely depending on the weather. Since ‘flywheel energy storage systems’ (FWSSs) do not use chemical reactions, they do not deteriorate due to charge or discharge. This is an advantage of FWSSs in applications for renewable energy plants. A conventional FWSS has capacity limitation because of the mechanical bearings used to support the flywheel. Therefore, we have designed a superconducting magnetic bearing composed of a superconducting coil stator and a superconducting bulk rotor in order to solve this problem, and have experimentally manufactured a large scale FWSS with a capacity of 100 kWh and an output power of 300 kW. The superconducting magnetic bearing can levitate 4 tons and enables the flywheel to rotate smoothly. A performance confirmation test will be started soon. An overview of the superconducting FWSS is presented in this paper.

  12. Available transmission capacity assessment

    Directory of Open Access Journals (Sweden)

    Škokljev Ivan

    2012-01-01

    Full Text Available Effective power system operation requires the analysis of vast amounts of information. Power market activities expose power transmission networks to high-level power transactions that threaten normal, secure operation of the power system. When there are service requests for a specific sink/source pair in a transmission system, the transmission system operator (TSO must allocate the available transfer capacity (ATC. It is common that ATC has a single numerical value. Additionally, the ATC must be calculated for the base case configuration of the system, while generation dispatch and topology remain unchanged during the calculation. Posting ATC on the internet should benefit prospective users by aiding them in formulating their requests. However, a single numerical value of ATC offers little for prospect for analysis, planning, what-if combinations, etc. A symbolic approach to the power flow problem (DC power flow and ATC offers a numerical computation at the very end, whilst the calculation beforehand is performed by using symbols for the general topology of the electrical network. Qualitative analysis of the ATC using only qualitative values, such as increase, decrease or no change, offers some new insights into ATC evaluation, multiple transactions evaluation, value of counter-flows and their impact etc. Symbolic analysis in this paper is performed after the execution of the linear, symbolic DC power flow. As control variables, the mathematical model comprises linear security constraints, ATC, PTDFs and transactions. The aim is to perform an ATC sensitivity study on a five nodes/seven lines transmission network, used for zonal market activities tests. A relatively complicated environment with twenty possible bilateral transactions is observed.

  13. A new self-propelled magnetic bearing with helical windings

    Science.gov (United States)

    Shayak, B.

    2016-12-01

    In this work, a design is proposed for an active, permanent magnet based, self-propelled magnetic bearing, i.e. levitating motor having the following features: (i) simple winding structure, (ii) high load supporting capacity, (iii) no eccentricity sensors, (iv) stable confinement in all translational dimensions, (v) stable confinement in all rotational dimensions, and (vi) high efficiency. This design uses an architecture consisting of a helically wound three-phase stator, and a rotor with the magnets also arranged in a helical manner. Active control is used to excite the rotor at a torque angle lying in the second quadrant. This torque angle is independent of the rotor's position inside the stator cavity; hence the control algorithm is similar to that of a conventional permanent magnet synchronous motor. It is motivated through a physical argument that the bearing rotor develops a lift force proportional to the output torque and that it remains stably confined in space. These assertions are then proved rigorously through a calculation of the magnetic fields, forces and torques. The stiffness matrix of the system is presented and a discussion of stable and unstable operating regions is given.

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

    Directory of Open Access Journals (Sweden)

    Castiglione Roberto

    2015-01-01

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

  15. Prospects for application of robotic mechano-hydraulical excavation of gas-bearing coal layers at great depths

    Science.gov (United States)

    Fryanov, V. N.; Pavlova, L. D.

    2016-10-01

    In the paper the scientific basis for robotic technology of excavation prone to gas- dynamic phenomena of a coal layer with high gas-bearing capacity at great depths is developed. The constructive scheme of automated remote-controlled mining robot, that fractures coal by high-pressure hydraulic jets in the gas polluted environment, is proposed.

  16. North Cascades Grizzly Bear Ecosystem Evaluation

    Data.gov (United States)

    Oak Ridge National Laboratory — We conducted a 6-year evaluation of the North Cascades Grizzly Bear Ecosystem (NCGBE) in north-central Washington to determine the suitability of the area to support...

  17. Polar bear research in Alaska, spring 1982

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — An investigation of the ecology and population dynamics of Alaskan polar bears has continued since 1967. As part of that program, U.S. Fish and Wildlife Service...

  18. Telemetry techniques used on Kodiak brown bear

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report summarizes the results of a study on the techniques used to monitor the movements of Kodiak brown bears instrumented with radio transmitters. Methods...

  19. Mercury biomagnification in polar bears ( Ursus maritimus)

    Science.gov (United States)

    Horton, T. W.; Blum, J. D.; Xie, Z.; Hren, M.; Chamberlain, C. P.

    2007-12-01

    Mercury biomagnification occurs in a variety of ecosystems resulting in greater potential for toxicological effects in higher-level trophic feeders. However, Hg transport pathways through different foodweb channels are not well known, particularly in high-latitude systems affected by atmospheric Hg deposition associated with snow and ice. Stable carbon and nitrogen isotope ratios and Hg concentrations determined for 26 late 19th and early 20th century polar bear hair specimens collected from cataloged museum collections elucidate relationships between high latitude marine foodweb structure and Hg transport pathways. Nitrogen and carbon isotopic compositions suggest that polar bears derive nutrition from both open water (pelagic) and ice associated (sympagic) foodweb channels. Correlation between Hg concentrations and nitrogen isotope compositions indicate mercury biomagnification occurred in most of the polar bears investigated. Interpretation of stable isotope based foodweb structure in concert with Hg concentrations further suggests that Hg biomagnification occurred to a greater degree in polar bears participating in pelagic foodweb channels.

  20. Bear Lake-Minidoka - Phragmites Control

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Bear Lake: Phragmites patches were sprayed on the refuge & north of the lake proper. Minidoka: patches along the Snake River & Lake Walcott were treated with...

  1. Polar bear research in Alaska, spring 1981

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — An investigation of the ecology and population dynamics of Alaskan polar bears has continued since 1967. As part of that program, U.S. Fish and Wildlife Service...

  2. AX-5 space suit bearing torque investigation

    Science.gov (United States)

    Loewenthal, Stuart; Vykukal, Vic; Mackendrick, Robert; Culbertson, Philip, Jr.

    1990-01-01

    The symptoms and eventual resolution of a torque increase problem occurring with ball bearings in the joints of the AX-5 space suit are described. Starting torques that rose 5 to 10 times initial levels were observed in crew evaluation tests of the suit in a zero-g water tank. This bearing problem was identified as a blocking torque anomaly, observed previously in oscillatory gimbal bearings. A large matrix of lubricants, ball separator designs and materials were evaluated. None of these combinations showed sufficient tolerance to lubricant washout when repeatedly cycled in water. The problem was resolved by retrofitting a pressure compensated, water exclusion seal to the outboard side of the bearing cavity. The symptoms and possible remedies to blocking are discussed.

  3. Cavitation Peening of Aerospace Bearings Project

    Data.gov (United States)

    National Aeronautics and Space Administration — High-value bearings are a critical part of the safety, reliability, cost and performance of modern aircraft. A typical passenger jet will have 100 to 175 high-valve...

  4. The polar bear and its protection

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — No census has been made of the polar bear population and indeed the general movements of the animals within their range are poorly known. At present it is not...

  5. LIGHT-WEIGHT LOAD-BEARING STRUCTURE

    DEFF Research Database (Denmark)

    2009-01-01

    The invention relates to a light-weight load-bearing structure (1) with optimized compression zone (2), where along one or more compression zones (2) in the structure (1) to be cast a core (3) of strong concrete is provided, which core (3) is surrounded by concrete of less strength (4) compared...... to the core (3) of strong concrete. The invention also relates to a method of casting of light-weight load-bearing structures (1) with optimized compression zone (2) where one or more channels, grooves, ducts, pipes and/or hoses (5) formed in the load-bearing structure (1) serves as moulds for moulding one...... or more cores (3) of strong concrete in the light-weight load-bearing structure (1)....

  6. Active Magnetic Bearings – Magnetic Forces

    DEFF Research Database (Denmark)

    Kjølhede, Klaus

    2006-01-01

    Parameter identification procedures and model validation are major steps towards intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model...... validation and leads to novel approaches in identifying crucial rotor parameters. This is the main focus of this paper, where an intelligent AMB is being developed with the aim of aiding the accurate identification of damping and stiffness coefficients of journal bearings and seals. The main contribution...... of the magnetic forces are led by using different experimental tests: (I) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor; (II) by measuring the input current and bearing...

  7. Active magnetic bearings used as exciters for rolling element bearing outer race defect diagnosis.

    Science.gov (United States)

    Xu, Yuanping; Di, Long; Zhou, Jin; Jin, Chaowu; Guo, Qintao

    2016-03-01

    The active health monitoring of rotordynamic systems in the presence of bearing outer race defect is considered in this paper. The shaft is assumed to be supported by conventional mechanical bearings and an active magnetic bearing (AMB) is used in the mid of the shaft location as an exciter to apply electromagnetic force to the system. We investigate a nonlinear bearing-pedestal system model with the outer race defect under the electromagnetic force. The nonlinear differential equations are integrated using the fourth-order Runge-Kutta algorithm. The simulation and experimental results show that the characteristic signal of outer race incipient defect is significantly amplified under the electromagnetic force through the AMBs, which is helpful to improve the diagnosis accuracy of rolling element bearing׳s incipient outer race defect.

  8. Effects of fluid inertia and bearing flexibility on the performance of finite length journal bearing

    Science.gov (United States)

    Javorova, Juliana; Alexandrov, Vassil

    2017-02-01

    The paper describes the theoretical study concerning the effect of lubricant inertia forces and deformability of the bearing elastic layer on the performance of a plane journal bearing. The problem is investigated for a Newtonian lubricant under isothermal and isoviscous conditions. The analysis considers the generalized Reynolds equation governing the flow of lubricant in the clearance space and the linear elasticity equation governing the displacement field in the bearing shell. An iterative numerical procedure with successive over relaxation is used to pressure distribution within the lubricated conjunction. Bearing performance characteristics have been presented for typically selected values of generalized Reynolds number Re* and elasticity parameters of the elastic liner. It has been observed that the combined effect of fluid inertia forces and bearing flexibility affects the performance characteristics of dynamically loaded journal bearing.

  9. Passive magnetic bearings for vehicular electromechanical batteries

    Energy Technology Data Exchange (ETDEWEB)

    Post, R

    1996-03-01

    This report describes the design of a passive magnetic bearing system to be used in electromechanical batteries (flywheel energy storage modules) suitable for vehicular use. One or two such EMB modules might, for example, be employed in a hybrid-electric automobile, providing efficient means for power peaking, i.e., for handling acceleration and regenerative braking power demands at high power levels. The bearing design described herein will be based on a ''dual-mode'' operating regime.

  10. Silicon Nitride Balls For Cryogenic Bearings

    Science.gov (United States)

    Butner, Myles F.; Ng, Lillian W.

    1990-01-01

    Resistance to wear greater than that of 440C steel. Experiments show lives of ball bearings immersed in liquid nitrogen or liquid oxygen increased significantly when 440C steel balls (running on 440C steel races) replaced by balls of silicon nitride. Developed for use at high temperatures, where lubrication poor or nonexistent. Best wear life of any bearing tested to date and ball material spalls without fracturing. Plans for future tests call for use of liquid oxygen as working fluid.

  11. Flywheel energy storage with superconductor magnetic bearings

    Energy Technology Data Exchange (ETDEWEB)

    Weinberger, Bernard R. (Avon, CT); Lynds, Jr., Lahmer (Glastonbury, CT); Hull, John R. (Hinsdale, IL)

    1993-01-01

    A flywheel having superconductor bearings has a lower drag to lift ratio that translates to an improvement of a factor of ten in the rotational decay rate. The lower drag results from the lower dissipation of melt-processed YBCO, improved uniformity of the permanent magnet portion of the bearings, operation in a different range of vacuum pressure from that taught by the art, and greater separation distance from the rotating members of conductive materials.

  12. Active magnetic bearings for optimum turbomachinery design

    Science.gov (United States)

    Hustak, J.; Kirk, R. G.; Schoeneck, K. A.

    1985-01-01

    The design and shop test results are given for a high speed eight stage centrifugal compressor supported by active magnetic bearings. A brief summary of the rotor dynamics analysis is presented with specific attention given to design considerations for optimum rotor stability. The concerns for retrofit of magnetic bearings in existing machinery are discussed with supporting analysis of a four stage centrifugal compressor. Recommendations are given on design and analysis requirements for successful machinery operation of either retrofit or new design turbomachinery.

  13. Peak capacity in unidimensional chromatography.

    Science.gov (United States)

    Neue, Uwe Dieter

    2008-03-14

    The currently existing knowledge about peak capacity in unidimensional separations is reviewed. The majority of the paper is dedicated to reversed-phase gradient chromatography, covering specific techniques as well as the subject of peak compression. Other sections deal with peak capacity in isocratic chromatography, size-exclusion chromatography and ion-exchange chromatography. An important topic is the limitation of the separation power and the meaning of the concept of peak capacity for real applications.

  14. On Cellular MIMO Channel Capacity

    Science.gov (United States)

    Adachi, Koichi; Adachi, Fumiyuki; Nakagawa, Masao

    To increase the transmission rate without bandwidth expansion, the multiple-input multiple-output (MIMO) technique has recently been attracting much attention. The MIMO channel capacity in a cellular system is affected by the interference from neighboring co-channel cells. In this paper, we introduce the cellular channel capacity and evaluate its outage capacity, taking into account the frequency-reuse factor, path loss exponent, standard deviation of shadowing loss, and transmission power of a base station (BS). Furthermore, we compare the cellular MIMO downlink channel capacity with those of other multi-antenna transmission techniques such as single-input multiple-output (SIMO) and space-time block coded multiple-input single-output (STBC-MISO). We show that the optimum frequency-reuse factor F that maximizes 10%-outage capacity is 3 and both 50%- and 90%-outage capacities is 1 irrespective of the type of multi-antenna transmission technique, where q%-outage capacity is defined as the channel capacity that gives an outage probability of q%. We also show that the cellular MIMO channel capacity is always higher than those of SIMO and STBC-MISO.

  15. Optimization of residual heat removal pump axial thrust and axial bearing

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, F.

    1996-12-01

    The residual heat removal (RHR) pumps of German 1300 megawatt pressurized-water reactor (PWR) power plants are of the single stage end suction type with volute casing or with diffuser and forged circular casing. Due to the service conditions the pumps have to cover the full capacity range as well as a big variation in suction static pressure. This results in a big difference in the axial thrust that has to be borne by the axial bearing. Because these pumps are designed to operate without auxiliary systems (things that do not exist can not fail), they are equipped with antifriction bearings and sump oil lubrication. To minimize the heat production within the bearing casing, a number of PWR plants have pumps with combined axial/radial bearings of the ball type. Due to the fact that the maximum axial thrust caused by static pressure and hydrodynamic forces on the impeller is too big to be borne by that type of axial bearing, the impellers were designed to produce a hydrodynamic axial force that counteracts the static axial force. Thus, the resulting axial thrust may change direction when the static pressure varies.

  16. Rotordynamics and bearing design of turbochargers

    Science.gov (United States)

    Chen, Wen Jeng

    2012-05-01

    Turbochargers have gained significant attention in recent years. They are already widely used in automotive, locomotive, and marine applications with diesel engines. They are also applied in the aerospace application to increase the engine performance now. The turbochargers used in automotive and aerospace industry are very light-weight with operating speeds above 100,000 rpm. The turbochargers used in locomotive and marine applications are relatively heavy in size and power compared to the automotive and aerospace applications, and the maximum continuous operating speeds are around 30,000 rpm depending on the diesel engine power rating. Floating ring bushings, semi-floating dampers, ball bearings, and ball bearings with dampers are commonly used in automotive applications for small turbochargers. However, these bearings may not be appropriate for large turbochargers in locomotive and marine applications. Instead, multi-lobed bearings with and without squeeze film dampers are commonly used in these heavy-duty turbochargers. This paper deals with the rotordynamic characteristics of larger turbochargers in locomotive and marine applications. Various bearing designs are discussed. Bearing design parameters are studied and optimal values are suggested. Test results are also presented to support the analytical simulation.

  17. Bearing and gear steels for aerospace applications

    Science.gov (United States)

    Zaretsky, Erwin V.

    1990-01-01

    Research in metallurgy and processing for bearing and gear steels has resulted in improvements in rolling-element bearing and gear life for aerospace application by a factor of approximately 200 over that obtained in the early 1940's. The selection and specification of a bearing or gear steel is dependent on the integration of multiple metallurgical and physical variables. For most aerospace bearings, through-hardened VIM-VAR AISI M-50 steel is the material of preference. For gears, the preferential material is case-carburized VAR AISI 9310. However, the VAR processing for this material is being replaced by VIM-VAR processing. Since case-carburized VIM-VAR M-50NiL incorporates the desirable qualities of both the AISI M-50 and AISI 9310 materials, optimal life and reliability can be achieved in both bearings and gears with a single steel. Hence, this material offers the promise of a common steel for both bearings and gears for future aerospace applications.

  18. Capacity Measurement with the UIC 406 Capacity Method

    DEFF Research Database (Denmark)

    Landex, Alex; Schittenhelm, Bernd; Kaas, Anders H.;

    2008-01-01

    This article describes the fast and effective UIC 406 method for calculating capacity consumption on railway lines. It is possible to expound the UIC 406 method in different ways which can lead to different capacity consumptions. Therefore, this article describes how the methodology is expounded ...

  19. Combined Effects of Gravity, Bending Moment, Bearing Clearance, and Input Torque on Wind Turbine Planetary Gear Load Sharing: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Y.; Keller, J.; LaCava, W.

    2012-09-01

    This computational work investigates planetary gear load sharing of three-mount suspension wind turbine gearboxes. A three dimensional multibody dynamic model is established, including gravity, bending moments, fluctuating mesh stiffness, nonlinear tooth contact, and bearing clearance. A flexible main shaft, planetary carrier, housing, and gear shafts are modeled using reduced degrees-of-freedom through modal compensation. This drivetrain model is validated against the experimental data of Gearbox Reliability Collaborative for gearbox internal loads. Planet load sharing is a combined effect of gravity, bending moment, bearing clearance, and input torque. Influences of each of these parameters and their combined effects on the resulting planet load sharing are investigated. Bending moments and gravity induce fundamental excitations in the rotating carrier frame, which can increase gearbox internal loads and disturb load sharing. Clearance in carrier bearings reduces the bearing load carrying capacity and thus the bending moment from the rotor can be transmitted into gear meshes. With bearing clearance, the bending moment can cause tooth micropitting and can induce planet bearing fatigue, leading to reduced gearbox life. Planet bearings are susceptible to skidding at low input torque.

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

    Science.gov (United States)

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

    2002-01-01

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

  1. Polar bears: the fate of an icon.

    Science.gov (United States)

    Fitzgerald, Kevin T

    2013-11-01

    Polar bears are one of the most iconic animals on our planet. Worldwide, even people who would never see one are drawn to these charismatic arctic ice hunters. They are the world's largest terrestrial carnivore, and despite being born on land, they spend most of their lives out on the sea ice and are considered a marine mammal. Current global studies estimate there are around 20,000 animals in some 19 discrete circumpolar populations. Aside from pregnant females denning in the winter months to give birth, the white bears do not hibernate. They spend their winters on the sea ice hunting seals, an activity they are spectacularly adapted for. Research on these animals is incredibly difficult because of the inhospitable surroundings they inhabit and how inaccessible they make the bears. For many years, the sum of our understanding of the natural history of polar bears came from tracks, scats, the remains of their kills, abandoned dens, and anecdotal observations of native hunters, explorers, and early biologists. Nonetheless, the last 40 years have seen a much better picture of their biology emerge thanks to, first, dedicated Canadian researchers and, later, truly international efforts of workers from many countries. Veterinarians have contributed to our knowledge of the bears by delivering and monitoring anesthesia, obtaining blood samples, performing necropsies, investigating their reproduction, conducting radiotelemetry studies, and examining their behavior. Recently, new technologies have been developed that revolutionize the study of the lives and natural history of undisturbed polar bears. These advances include better satellite radiotelemetry equipment and the development of remote-controlled miniature devices equipped with high-definition cameras. Such new modalities provide dramatic new insights into the life of polar bears. The remarkable degree of specialized adaptation to life on the sea ice that allowed the bears to be successful is the very reason that

  2. Checking Capacity for MIMO Configurations

    DEFF Research Database (Denmark)

    Thaysen, Jesper; Jakobsen, Kaj Bjarne

    2007-01-01

    Wireless system capacity can be added by increasing the number of antennas in a MIMO setup or by carefully optimizing the performance of a smaller number of antennas.......Wireless system capacity can be added by increasing the number of antennas in a MIMO setup or by carefully optimizing the performance of a smaller number of antennas....

  3. Fiscal Capacity Equalisation in Tanzania

    NARCIS (Netherlands)

    Allers, Maarten A.; Ishemoi, Lewis J.

    2010-01-01

    Fiscal equalisation aims at enabling decentralised governments to supply similar services at similar tax rates. In order to equalise fiscal disparities, differences in both fiscal capacities and in fiscal needs have to be measured. This paper focuses on the measurement of fiscal capacity in a develo

  4. Improving African health research capacity

    DEFF Research Database (Denmark)

    Lazarus, Jeff; Wallace, Samantha A; Liljestrand, Jerker

    2010-01-01

    The issue of strengthening local research capacity in Africa is again high on the health and development agenda. The latest initiative comes from the Wellcome Trust. But when it comes to capacity development, one of the chief obstacles that health sectors in the region must confront is the migrat...

  5. Information capacity of quantum observable

    CERN Document Server

    Holevo, A S

    2011-01-01

    In this paper we consider the classical capacities of quantum-classical channels corresponding to measurement of observables. Special attention is paid to the case of continuous observables. We give the formulas for unassisted and entanglement-assisted classical capacities $C,C_{ea}$ and consider some explicitly solvable cases which give new examples of entanglement-breaking channels with $C_{ea}>C.$

  6. Capacity Building in Land Administration

    DEFF Research Database (Denmark)

    Enemark, Stig; Williamson, I

    2004-01-01

    Capacity building increasingly seen as a key component of land administration projects in developing and countries in transition undertaken by the international development banks and individual country development assistance agencies. However, the capacity building concept is often used within...... infrastructures for implementing land policies in a sustainable way. Where a project is established to create land administration infrastructures in developing or transition countries, it is critical that capacity building is a mainstream component, not as an add-on, which is often the case. In fact such projects...... should be dealt with as capacity building projects in themselves.    The article introduces a conceptual analytical framework that provides some guidance when dealing with capacity building for land administration in support of a broader land policy agenda....

  7. Wear numbers for ball cup and journal bearings

    NARCIS (Netherlands)

    Ligterink, D.J.; Moes, H.

    1980-01-01

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

  8. 49 CFR 230.102 - Tender plain bearing journal boxes.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Tender plain bearing journal boxes. 230.102... Locomotives and Tenders Running Gear § 230.102 Tender plain bearing journal boxes. Plain bearing journal boxes... expected to damage the bearing; or have a detrimental effect on the lubrication of the journal and...

  9. Nonlinear vibrations and stability of aerostatic bearing

    Directory of Open Access Journals (Sweden)

    Kozánek J.

    2008-12-01

    Full Text Available Bearings based on aerostatic principle belong to the new machine elements advantageous for low- and high-speed applications, but their dynamic and stability properties are not yet sufficiently known. This paper presents a new elaborated method and gained results of theoretical investigation of dynamic properties of aerostatic bearing in general dimensionless form. It is aimed also as a supporting tool for diagnostic and identification methods used at developing of new bearings proposed by TECHLAB, Prague for industrial applications. Mathematical model expresses nonlinear and evolutive properties in the entire area of bearing clearance, contains sufficient number of free parameters in functions of restoring and damping forces and can therefore describe all types of motions occurring in gas bearings as periodic, quasi-periodic, including beats and instability, which can leads to chaotic and self-excited vibrations. The influence of non-diagonal elements of stiffness and damping matrices of linearized model on the spectral properties and the stability of system is investigated, too.

  10. Oxford phase III meniscal bearing fracture: case report.

    Science.gov (United States)

    Lim, Hong-Chul; Shon, Won-Yong; Kim, Seung-Ju; Bae, Ji-Hoon

    2014-01-01

    Meniscal bearing fracture is a rare complication of phase III Oxford unicompartmental knee replacement (UKR). We report a case of a meniscal bearing fracture that occurred 7 years after phase III Oxford medial UKR. The meniscal bearing showed uneven delamination of the polyethylene in the thinnest articular surface and an impingement lesion. This lesion initiated a fatigue crack that propagated to cause failure of the meniscal bearing. This is the first report of a meniscal bearing fracture without a posterior marker wire.

  11. Wear numbers for ball cup and journal bearings

    OpenAIRE

    Ligterink, D.J.; Moes, H.

    1980-01-01

    A wear number is defined for ball cup bearings and for journal bearings where the cup and the cylindrical bearing are made of soft material. This dimensionless wear number provides a relation between the following five quantities: the radius of the ball or the length of the journal bearing in millimetres, the wear modulus in newtons per square millimetre, the maximum wear depth rate of the cup or the cylindrical bearing in millimetres per second, the force between the mating surfaces in newto...

  12. Bearing tester data compilation, analysis and reporting and bearing math modeling, volume 1

    Science.gov (United States)

    Marshall, D. D.; Montgomery, E. E.; New, L. S.; Stone, M. A.; Tiller, B. K.

    1984-01-01

    Thermal and mechanical models of high speed angular contact ball bearings operating in LOX and LN2 were developed and verified with limited test data in an effort to further understand the parameters that determine or effect the SSME turbopump bearing operational characteristics and service life. The SHABERTH bearing analysis program which was adapted to evaluate shaft bearing systems in cryogenics is not capable of accommodating varying thermal properties and two phase flow. A bearing model with this capability was developed using the SINDA thermal analyzer. Iteration between the SHABERTH and the SINDA models enable the establishment of preliminary bounds for stable operation in LN2. These limits were established in terms of fluid flow, fluid inlet temperature, and axial load for a shaft speed of 30,000 RPM.

  13. Bear bile: dilemma of traditional medicinal use and animal protection

    Directory of Open Access Journals (Sweden)

    Nagamatsu Tadashi

    2009-01-01

    Full Text Available Abstract Bear bile has been used in Traditional Chinese Medicine (TCM for thousands of years. Modern investigations showed that it has a wide range of pharmacological actions with little toxicological side effect and the pure compounds have been used for curing hepatic and biliary disorders for decades. However, extensive consumption of bear bile made bears endangered species. In the 1980's, bear farming was established in China to extract bear bile from living bears with "Free-dripping Fistula Technique". Bear farming is extremely inhumane and many bears died of illness such as chronic infections and liver cancer. Efforts are now given by non-governmental organizations, mass media and Chinese government to end bear farming ultimately. At the same time, systematic research has to be done to find an alternative for bear bile. In this review, we focused on the literature, laboratory and clinical results related to bear bile and its substitutes or alternative in English and Chinese databases. We examined the substitutes or alternative of bear bile from three aspects: pure compounds derived from bear bile, biles from other animals and herbs from TCM. We then discussed the strategy for stopping the trading of bear bile and issues of bear bile related to potential alternative candidates, existing problems in alternative research and work to be done in the future.

  14. Powder metallurgy bearings for advanced rocket engines

    Science.gov (United States)

    Fleck, J. N.; Killman, B. J.; Munson, H.E.

    1985-01-01

    Traditional ingot metallurgy was pushed to the limit for many demanding applications including antifriction bearings. New systems require corrosion resistance, better fatigue resistance, and higher toughness. With conventional processing, increasing the alloying level to achieve corrosion resistance results in a decrease in other properties such as toughness. Advanced powder metallurgy affords a viable solution to this problem. During powder manufacture, the individual particle solidifies very rapidly; as a consequence, the primary carbides are very small and uniformly distributed. When properly consolidated, this uniform structure is preserved while generating a fully dense product. Element tests including rolling contact fatigue, hot hardness, wear, fracture toughness, and corrosion resistance are underway on eleven candidate P/M bearing alloys and results are compared with those for wrought 440C steel, the current SSME bearing material. Several materials which offer the promise of a significant improvement in performance were identified.

  15. Robust Bearing Estimation for 3-Component Stations

    Energy Technology Data Exchange (ETDEWEB)

    Claassen, John P.

    1999-06-03

    A robust bearing estimation process for 3-component stations has been developed and explored. The method, called SEEC for Search, Estimate, Evaluate and Correct, intelligently exploits the in- herent information in the arrival at every step of the process to achieve near-optimal results. In particular, the approach uses a consistent framework to define the optimal time-frequency windows on which to make estimates, to make the bearing estimates themselves, to construct metrics helpful in choosing the better estimates or admitting that the bearing is immeasurable, andjinally to apply bias corrections when calibration information is available to yield a single final estimate. The method was applied to a small but challenging set of events in a seismically active region. The method demonstrated remarkable utility by providing better estimates and insights than previously available. Various monitoring implications are noted fiom these findings.

  16. Robust bearing estimation for 3-component stations

    Energy Technology Data Exchange (ETDEWEB)

    CLAASSEN,JOHN P.

    2000-02-01

    A robust bearing estimation process for 3-component stations has been developed and explored. The method, called SEEC for Search, Estimate, Evaluate and Correct, intelligently exploits the inherent information in the arrival at every step of the process to achieve near-optimal results. In particular the approach uses a consistent framework to define the optimal time-frequency windows on which to make estimates, to make the bearing estimates themselves, to construct metrics helpful in choosing the better estimates or admitting that the bearing is immeasurable, and finally to apply bias corrections when calibration information is available to yield a single final estimate. The algorithm was applied to a small but challenging set of events in a seismically active region. It demonstrated remarkable utility by providing better estimates and insights than previously available. Various monitoring implications are noted from these findings.

  17. Trace fossils in coal-bearing sequences

    Energy Technology Data Exchange (ETDEWEB)

    Pollard, J.E.

    1988-03-01

    In the past decade trace fossils have been recorded extensively from coal-bearing sediments, differing widely in facies, age and location. Westphalian or Stephanian 'coal-measures' in Britain, Europe and Eastern Canada contain an ichnofauna produced by invertebrates and/or vertebrates in upper delta plain sediments. This contrasts with the marine-related lower delta plain ichnofaunas known from Pennsylvanian rocks of the United States and Permian Gondwana 'coal-measures' of South Africa. Deltaic complexes of Middle Jurassic age in the North Sea basin and Upper Cretaceous age in North America contain marine trace fossils and dinosaur footprints in coastal coal- bearing facies. These case histories illustrate the importance of trace fossils both in facies analysis of coal-bearing sequences and in recording the presence of animals rarely known as body fossils in such clastic sediments. 80 refs., 5 figs.

  18. Demography of the Yellowstone grizzly bears

    Science.gov (United States)

    Pease, C.M.; Mattson, D.J.

    1999-01-01

    We undertook a demographic analysis of the Yellowstone grizzly bears (Ursus arctos) to identify critical environmental factors controlling grizzly bear vital rates, and thereby to help evaluate the effectiveness of past management and to identify future conservation issues. We concluded that, within the limits of uncertainty implied by the available data and our methods of data analysis, the size of the Yellowstone grizzly bear population changed little from 1975 to 1995. We found that grizzly bear mortality rates are about double in years when the whitebark pine crop fails than in mast years, and that the population probably declines when the crop fails and increases in mast years. Our model suggests that natural variation in whitebark pine crop size over the last two decades explains more of the perceived fluctuations in Yellowstone grizzly population size than do other variables. Our analysis used demographic data from 202 radio-telemetered bears followed between 1975 and 1992 and accounted for whitebark pine (Pinus albicaulis) crop failures during 1993-1995. We used a maximum likelihood method to estimate demographic parameters and used the Akaike Information Criteria to judge the significance of various independent variables. We identified no independent variables correlated with grizzly bear fecundity. In order of importance, we found that grizzly bear mortality rates are correlated with season, whitebark pine crop size (mast vs. nonmast year), sex, management-trapping status (never management-trapped vs. management-trapped once or more), and age. The mortality rate of bears that were management-trapped at least once was almost double that of bears that were never management-trapped, implying a source/sink (i.e., never management-trapped/management-trapped) structure. The rate at which bears move between the source and sink, estimated as the management-trapping rate (h), is critical to estimating the finite rate of increase, I>I?. We quantified h by

  19. STABILITY OF ROTOR-BEARING SYSTEMS

    Directory of Open Access Journals (Sweden)

    Uğur YÜCEL

    2003-03-01

    Full Text Available In various industrial applications there is a need for higher speed, yet reliably operating rotating machinery. A key factor in achieving this type of machinery continues to be the ability to accurately predict the dynamic response and stability of a rotor-bearing system. This paper introduces and explains the nature of rotordynamic phenomena from comparatively simple analytic models. Starting with the most simple rotor model that is supported in two rigid bearings at its ends, the more realistic and more involved cases are considered by incorporating the effects of flexible bearings. Knowledge of these phenomena is fundamental to an understanding of the behavior of complex models, which corresponds to the real rotors of turbomachines.

  20. Hydrolyzable polyureas bearing hindered urea bonds.

    Science.gov (United States)

    Ying, Hanze; Cheng, Jianjun

    2014-12-10

    Hydrolyzable polymers are widely used materials that have found numerous applications in biomedical, agricultural, plastic, and packaging industrials. They usually contain ester and other hydrolyzable bonds, such as anhydride, acetal, ketal, or imine, in their backbone structures. Here, we report the first design of hydrolyzable polyureas bearing dynamic hindered urea bonds (HUBs) that can reversibly dissociate to bulky amines and isocyanates, the latter of which can be further hydrolyzed by water, driving the equilibrium to facilitate the degradation of polyureas. Polyureas bearing 1-tert-butyl-1-ethylurea bonds that show high dynamicity (high bond dissociation rate), in the form of either linear polymers or cross-linked gels, can be completely degraded by water under mild conditions. Given the simplicity and low cost for the production of polyureas by simply mixing multifunctional bulky amines and isocyanates, the versatility of the structures, and the tunability of the degradation profiles of HUB-bearing polyureas, these materials are potentially of very broad applications.

  1. High Performance Magnetic Bearings for Aero Applications

    Science.gov (United States)

    Allaire, P. E.; Knospe, C. R.; Williams, R. D.; Lewis, D. W.; Barrett, L. E.; Maslen, E. H.; Humphris, R. R.

    1997-01-01

    Several previous annual reports were written and numerous papers published on the topics for this grant. That work is not repeated here in this final report. Only the work completed in the final year of the grant is presented in this final report. This final year effort concentrated on power loss measurements in magnetic bearing rotors. The effect of rotor power losses in magnetic bearings are very important for many applications. In some cases, these losses must be minimized to maximize the length of time the rotating machine can operate on a fixed energy or power supply. Examples include aircraft gas turbine engines, space devices, or energy storage flywheels. In other applications, the heating caused by the magnetic bearing must be removed. Excessive heating can be a significant problem in machines as diverse as large compressors, electric motors, textile spindles, and artificial heart pumps.

  2. Experimental investigations of active air bearings

    DEFF Research Database (Denmark)

    Santos, Ilmar; Morosi, Stefano

    2012-01-01

    Along with traditional oil lubrication, increasing demand for high-speed applications has renewed attention to gas bearings technology. Traditional aerostatic and aerodynamic gas lubrication has been widely used in a variety of applications, ranging from high-speed spindles to micro and meso......-scale turbomachinery. The present paper deals with experimental rotordynamic testing of a flexible rotor supported by hybrid aerostaticaerodynamic gas journal bearing equipped with an electronic radial air injection system. From a rotordynamic point of view there are two phenomena that limit the widespread...... of traditional gas lubrication: 1) Low damping makes operation across critical speed dangerous, as even low level of unbalance can generate large vibration responses. This is especially problematic for gas bearing applications, which often operate in the supercritical region. Moreover, 2) An upper bound...

  3. Grizzly bear habitat selection is scale dependent.

    Science.gov (United States)

    Ciarniello, Lana M; Boyce, Mark S; Seip, Dale R; Heard, Douglas C

    2007-07-01

    The purpose of our study is to show how ecologists' interpretation of habitat selection by grizzly bears (Ursus arctos) is altered by the scale of observation and also how management questions would be best addressed using predetermined scales of analysis. Using resource selection functions (RSF) we examined how variation in the spatial extent of availability affected our interpretation of habitat selection by grizzly bears inhabiting mountain and plateau landscapes. We estimated separate models for females and males using three spatial extents: within the study area, within the home range, and within predetermined movement buffers. We employed two methods for evaluating the effects of scale on our RSF designs. First, we chose a priori six candidate models, estimated at each scale, and ranked them using Akaike Information Criteria. Using this method, results changed among scales for males but not for females. For female bears, models that included the full suite of covariates predicted habitat use best at each scale. For male bears that resided in the mountains, models based on forest successional stages ranked highest at the study-wide and home range extents, whereas models containing covariates based on terrain features ranked highest at the buffer extent. For male bears on the plateau, each scale estimated a different highest-ranked model. Second, we examined differences among model coefficients across the three scales for one candidate model. We found that both the magnitude and direction of coefficients were dependent upon the scale examined; results varied between landscapes, scales, and sexes. Greenness, reflecting lush green vegetation, was a strong predictor of the presence of female bears in both landscapes and males that resided in the mountains. Male bears on the plateau were the only animals to select areas that exposed them to a high risk of mortality by humans. Our results show that grizzly bear habitat selection is scale dependent. Further, the

  4. Wear Analysis of Wind Turbine Gearbox Bearings

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Peter Julian [ORNL; Walker, Larry R [ORNL; Xu, Hanbing [ORNL; Parten, Randy J [ORNL; Qu, Jun [ORNL; Geer, Tom [ORNL

    2010-04-01

    The objective of this effort was to investigate and characterize the nature of surface damage and wear to wind turbine gearbox bearings returned from service in the field. Bearings were supplied for examination by S. Butterfield and J. Johnson of the National Wind Technology Center (NREL), Boulder, Colorado. Studies consisted of visual examination, optical and electron microscopy, dimensional measurements of wear-induced macro-scale and micro-scale features, measurements of macro- and micro-scale hardness, 3D imaging of surface damage, studies of elemental distributions on fracture surfaces, and examinations of polished cross-sections of surfaces under various etched and non-etched conditions.

  5. Coated Conductors for the Magnetic Bearing Application

    Science.gov (United States)

    Sass, Felipe; Dias, Daniel Henrique Nogueira; Sotelo, Guilherme Gonçalves; Júnior, Rubens de Andrade

    The second generation (2G) of superconductor wires have been considered for several applications lately. This work presents a preliminary study of superconducting magnetic bearings (SMB) using 2G wires as passive levitators. A superconducting block using stacked 2G wires was built to evaluate the magnetic bearing behavior, thought levitation force measurements, when a permanent magnet cylinder approaches or moves away from the block. The superconducting block was compared with an YBCO bulk with nearly the same dimensions and the results show a promising potential for this application.

  6. Cavitation wear resistance of engine bearing materials

    Science.gov (United States)

    Rac, Aleksandar

    1994-04-01

    The resistance to cavitation erosion of aluminum alloy, and cast and sinte-red lead-bronze, materials which are most frequently used for engine bearings, has been evaluated. The tests were carried out in motor oil at a temperature of 80 C, using a magnetostrictive vibratory tester (20 kHz). The results showed that the cavitation erosion resistance was the greatest in cast lead-bronze. On the contrary, sintered lead-bronze, though of the same chemical composition, had the greatest erosion rate. Additionally, the investigation of the overlay plated bearings showed the overlay was nonresistive to this type of wear.

  7. Heat capacities of lanthanide and actinide monazite-type ceramics

    Science.gov (United States)

    Kowalski, Piotr M.; Beridze, George; Vinograd, Victor L.; Bosbach, Dirk

    2015-09-01

    (Ln, An)xPO4 monazite-type ceramics are considered as potential matrices for the disposal of nuclear waste. In this study we computed the heat capacities and the standard entropies of these compounds using density functional perturbation theory. The calculations of lanthanide monazites agree well with the existing experimental data and provide information on the variation of the standard heat capacities and entropies along the lanthanide series. The results for AnPO4 monazites are similar to those obtained for the isoelectronic lanthanide compounds. This suggests that the missing thermodynamic data on actinide monazites could be similarly computed or assessed based on the properties of their lanthanide analogs. However, the computed heat capacity of PuPO4 appear to be significantly lower than the measured data. We argue that this discrepancy might indicate potential problems with the existing experimental data or with their interpretation. This shows a need for further experimental studies of the heat capacities of actinide-bearing, monazite-type ceramics.

  8. Capacity-achieving CPM schemes

    CERN Document Server

    Perotti, Alberto; Benedetto, Sergio; Montorsi, Guido

    2008-01-01

    The pragmatic approach to coded continuous-phase modulation (CPM) is proposed as a capacity-achieving low-complexity alternative to the serially-concatenated CPM (SC-CPM) coding scheme. In this paper, we first perform a selection of the best spectrally-efficient CPM modulations to be embedded into SC-CPM schemes. Then, we consider the pragmatic capacity (a.k.a. BICM capacity) of CPM modulations and optimize it through a careful design of the mapping between input bits and CPM waveforms. The so obtained schemes are cascaded with an outer serially-concatenated convolutional code to form a pragmatic coded-modulation system. The resulting schemes exhibit performance very close to the CPM capacity without requiring iterations between the outer decoder and the CPM demodulator. As a result, the receiver exhibits reduced complexity and increased flexibility due to the separation of the demodulation and decoding functions.

  9. Quantum channel capacities - multiparty communication

    CERN Document Server

    Demianowicz, M; Demianowicz, Maciej; Horodecki, Pawel

    2006-01-01

    We analyze different aspects of multiparty communication over quantum memoryless channels and generalize some of key results known from bipartite channels to that of multiparty scenario. In particular, we introduce multiparty versions of minimal subspace transmission fidelity and entanglement transmission fidelity. We also provide alternative, local, versions of fidelities and show their equivalence to the global ones in context of capacity regions defined. The equivalence of two different capacity notions with respect to two types of the fidelities is proven. In analogy to bipartite case it is shown, via sufficiency of isometric encoding theorem, that additional classical forward side channel does not increase capacity region of any quantum channel with $k$ senders and $m$ receivers which represents a compact unit of general quantum networks theory. The result proves that recently provided capacity region of multiple access channel ([M. Horodecki et al, Nature {\\bf 436} 673 (2005)], [J.Yard et al, quant-ph/0...

  10. Capacity Building in Land Management

    DEFF Research Database (Denmark)

    Enemark, Stig; Ahene, Rexford

    2003-01-01

    There is a significant need for capacity building in the interdisciplinary area of land management especially in developing countries and countries in transition, to deal with the complex issues of building efficient land information systems and sustainable institutional infrastructures. Capacity...... building in land management is not only a question of establishing a sufficient technological level or sufficient economic resources. It is mainly a question of understanding the interdisciplinary and cross-sectoral nature of land administration systems, and understanding the need for human resource...... development in this area. Furthermore, capacity building should ensure that the focus is on building sound institutions and governance rather than just high-level IT-infrastructures.    This overall approach to capacity building in land management is used for implementing a new land policy reform in Malawi...

  11. Capacity Analysis on Multi-Lane Roundabouts: An Evaluation With Highway Capacity Manual 2010 Capacity Model

    Directory of Open Access Journals (Sweden)

    Melike Ersoy

    2014-06-01

    Full Text Available In this study, capacity estimations with the incorporation of Highway Capacity Manual (HCM 2010 method are evaluated. Parameter based sensitivity analysis on calculations with the new HCM formula and a comparative evaluation of the new methodology with two most common capacity analysis methods, i.e., the method of critical gap acceptance and the method of regression analysis, are performed. Maximum and minimum headway intervals of follow up time and critical gap parameters are alternated within the sensitivity analysis. The Transport Research Laboratory formula for regression and Australian formula for gap acceptance method are considered in comparison. Relative comparisons of predictions on capacity by HCM2010 method, regression analysis and gap acceptance method are presented considering field data obtained by observations at two roundabouts in Izmir, Turkey. The results of the study show that the HCM2010 formula led to lower capacity estimates than regression analysis and higher estimates than the gap acceptance method. Regarding the real capacity observations under high circulating flow-rates the HCM2010 method yielded to more appropriate results than the regression method. In addition to comparisons, studies on the sensitivity analysis show that entry capacity estimates possess sharper changes as smaller follow up headways are accepted.

  12. Carrying Capacity:An Overview

    Institute of Scientific and Technical Information of China (English)

    Chen Shaofeng

    2004-01-01

    The concept of carrying capacity is derived from ecology, with widespread contentions of its theoretical connotations and applications in the international academic community, especially the impact of human activities on the environment.Disputes on carrying capacity have been occurring not only among biologists and ecologists, but also among mainstream economists. Based on their efforts,the author makes an attempt to describe its origin,connotations, problems, measurement, and at the same time note the latest international progress in this field.

  13. Impact of Fixed-Bearing and Mobile-Bearing Tibial Insert in Unicondylar Knee Arthroplasty

    Directory of Open Access Journals (Sweden)

    Mehmet Faruk Çatma

    2016-06-01

    Full Text Available INTRODUCTION: The aim of the study is to investigate the impact of fixed or mobile-bearing tibial inserts on patellofemoral arthrosis and evaluate which one to be preferred for patients with patellofemoral arthrosis. METHODS: Operated in our clinic between January 2009 and February 2013, 33 with patellofemoral arthritis together with anteromedial compartment arthritis were included in the study. Patellofemoral joints of patients were evaluated according to the scoring system defined by Fulkerson-Shea. RESULTS: Unicondylar knee arthroplasty with fixed-bearing tibial insertsand 22 (66,6% (male: 3, female: 19 and unicondylar knee arthroplasty with mobile-bearing tibial inserts 11 (33,9 % (male: 2, female: 9 were implanted.Average knee flexion was found to be 116,5 (100-135 degrees in 22 patients with mobile-bearing tibial inserts, and 114,5 (95-135 in 11 patients with fixed-bearing tibial inserts. DISCUSSION AND CONCLUSION: Patellofemoral arthrosis is an important factor for unicondylar knee arthroplasty prognosis and one of the determinants of patient satisfaction. Significantly less patellofemoral complaints were seen with UKA with fixed-bearing tibial insert compared to mobile-bearing tibial insert.

  14. Dynamic Analysis of a Rotor-Bearing-SFD System with the Bearing Inner Race Defect

    Directory of Open Access Journals (Sweden)

    Junhong Zhang

    2017-01-01

    Full Text Available In this paper, the dynamic behavior of a rotor-bearing-SFD system with the inner race defect of bearing is investigated. The contact force between the rolling element and the race is calculated in Hertzian contact and elastohydrodynamic lubrication condition. The supporting force of the SFD is simulated by integrating the pressure distribution derived from Reynolds’s equation. The equations of motion of the rotor-bearing-SFD system are derived and solved using the fourth-order Runge-Kutta method. The dynamic behavior and the fault characteristics are analyzed with two configurations of the SFD: (1 mounted on the unfaulted bearing and (2 mounted on the faulty bearing. According to the analysis of time-frequency diagram, waterfall plot, and spectral diagram, the results show that the characteristics of inner race defects on bearing frequencies are related to the characteristic multiple frequency of the inner race defect and the fundamental frequency. The speed and defect width have different influence on the distribution and amplitude of frequency. The SFD can enhance the system stability under the bearing fault but the enhancement decreases with the increasing speed. Meanwhile, the beneficial effect of the SFD varies according to the mounted position in the rotor system.

  15. Local Attitudes towards Bear Management after Illegal Feeding and Problem Bear Activity

    Directory of Open Access Journals (Sweden)

    David Fraser

    2013-09-01

    Full Text Available The “pot bears” received international media attention in 2010 after police discovered the intentional feeding of over 20 black bears during the investigation of an alleged marijuana-growing operation in Christina Lake, British Columbia, Canada. A two-phase random digit dialing survey of the community was conducted in 2011 to understand local perspectives on bear policy and management, before and after a summer of problem bear activity and government interventions. Of the 159 households surveyed in February 2011, most had neutral or positive attitudes towards bears in general, and supported the initial decision to feed the food-conditioned bears until the autumn hibernation. In contrast to wildlife experts however, most participants supported relocating the problem bears, or allowing them to remain in the area, ahead of killing; in part this arose from notions of fairness despite the acknowledged problems of relocation. Most locals were aware of the years of feeding but did not report it, evidently failing to see it as a serious form of harm, even after many bears had been killed. This underscores the importance of preventive action on wildlife feeding and the need to narrow the gap between public and expert opinion on the likely effects of relocation versus killing.

  16. Lubricant replacement in rolling element bearings for weapon surety devices

    Energy Technology Data Exchange (ETDEWEB)

    Steinhoff, R.; Dugger, M.T.; Varga, K.S. [Sandia National Laboratories, Albuquerque, NM (United States)

    1996-05-01

    Stronglink switches are a weapon surety device that is critical to the nuclear safety theme in modem nuclear weapons. These stronglink switches use rolling element bearings which contain a lubricant consisting of low molecular weight polytetrafluoroethylene (PTFE) fragments. Ozone-depleting solvents are used in both the manufacture and application of this lubricant. An alternate bearing lubrication for stronglink switches is needed that will provide long-term chemical stability, low migration and consistent performance. Candidates that were evaluated include bearings with sputtered MoS{sub 2} on the races and retainers, bearings with TiC-coated balls, and bearings with Si{sub 3}N{sub 4} balls and steel races. These candidates were compared to the lubricants currently used which are bearings lubricated with PTFE fragments of low molecular weight in a fluorocarbon solvent. The candidates were also compared to bearings lubricated with a diester oil which is representative of bearing lubricants used in industrial applications. Evaluation consisted of cycling preloaded bearings and subjecting them to 23 gRMS random vibration. All of the candidates are viable substitutes for low load application where bearing preload is approximately 1 pound. For high load applications where the bearing preload is approximately 10 pounds, bearings with sputtered MoS{sub 2} on the races and retainers appear to be the best substitutes. Bearings with TiC-coated balls also appear to be a viable candidate but these bearings did not perform as well as the sputtered MoS{sub 2}.

  17. NANO-BEARING: THE DESIGN OF A NEW TYPE OF AIR BEARING WITH FLEXURE STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    KO Pui Hang; DU Ruxu

    2007-01-01

    A new type of air bearing with flexure structure is introduced. The new bearing is designed for precision mechanical engineering devices such as mechanical watch movement. The new design uses the flexure structure to provide 3D damping to absorb shocks from all directions. Two designs are presented: one has 12 T-shape slots in the radian direction while the other has 8 spiral slots in the radian direction. Both designs have flexure mountings on the axial directions. Based on the finite element analysis (FEA), the new bearing can reduce the vibration (displacement) by as much as 8.37% and hence, can better protect the shafts.

  18. Thermal and tilt effects on bearing characteristics of hydrostatic oil pad in rotary table

    Institute of Scientific and Technical Information of China (English)

    刘志峰; 湛承鹏; 程强; 赵永胜; 李小燕; 王义达

    2016-01-01

    Hydrostatic pads are key components of a constant flow compensation hydrostatic rotary table. The tilt and thermal effects due to the partial load, the manufacturing errors and the friction must be considered. However, designers are more likely inclined to ignore these effects. In this work, the coupled characteristics of the tilt and thermal effects are studied. A coupled mathematical model to calculate the bearing properties of the pads is built. This model takes into consideration of tilt and thermal effects and is used to solve the flow problem by the finite difference method. The characteristics of the oil pad, including, the recess pressures, the load carrying capacity and the damping coefficients, are obtained and the tilt and thermal effects are analyzed. It is observed that the tilt has a tremendous impact on the bearing characteristics of the hydrostatic pad. The recess pressure, the load carrying capacity and the stiffness are reduced by 50% and the pressure distribution and the temperature distribution of the oil film also change significantly. When the pads work under a tilt operation, a larger land width is better for its bearing properties. It is also observed that the thermal effect is significant and cannot be ignored.

  19. The stiffness change and the increase in the ultimate capacity for a stiff pile resulting from a cyclic loading

    DEFF Research Database (Denmark)

    Lada, Aleksandra; Ibsen, Lars Bo; Nicolai, Giulio

    In the paper the experimental results of small-scale tests on a stiff monopile are presented to outline the change in stiffness during the cyclic loading and the change in the ultimate pile capacity. The results confirm the increase of stiffness and the increase in bearing capacity resulting from...... cyclic loading. Performed analysis provides a better understanding of the problem and reveals some correlations that can be useful in the future design of stiff monopiles....

  20. MAGNETIC FLUID BEARINGS OF MINING EQUIPMENT

    Directory of Open Access Journals (Sweden)

    I. Gorlov

    2012-01-01

    Full Text Available The paper considers a problem pertaining to selection friction pair materials for plain bearings of mining equipment which are lubricated with  nano-dispersed magnetic oil. Methodology for equipment tests, technology for obtaining new anti-friction materials (polymer, ceramic, amorphous and investigation results are presented in the paper.