Articoli di riviste: "Spherical air bearing"

1

Masters, M. F., C. Reynolds, H. Suedhoff e F. M. DeArmond. "Construction of a simple spherical air bearing". American Journal of Physics 77, n. 8 (agosto 2009): 764–66. http://dx.doi.org/10.1119/1.3050161.

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Kok Kiong Tan, Sunan Huang, Wenyu Liang, A. A. Mamun, Eng Kiat Koh e Huixing Zhou. "Development of a Spherical Air Bearing Positioning System". IEEE Transactions on Industrial Electronics 59, n. 9 (settembre 2012): 3501–9. http://dx.doi.org/10.1109/tie.2011.2171179.

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Arun, Kumar S., A. Sekar e K. V. Govinda. "Aerostatic Spherical Bearing Manufacturing Methods and Criticalities - An Approach". Applied Mechanics and Materials 592-594 (luglio 2014): 28–32. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.28.

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In general, aerostatic bearings are flat bearings and the stringent manufacturing tolerances in geometric dimensions and profile will make the bearing ideal for obtaining high stiffness during measurement. Aerostatic Spherical Bearing (ASB) on the contrary is a special bearing which provides a frictionless pivot and allows three degrees of rotational freedom. Methods involved in manufacturing and realizing a highly stiff ASB is discussed in this paper. ASB components viz. Stator and Rotor of hemi-spherical in geometry are the critical components to be machined, which are used in Mass properties and Dynamic Balancing Measurement machine (MaPDBM). MaPDBM is used to measure mass, center of gravity, moments of inertia and static & dynamic unbalance of spacecraft. An air film of 25-50 μm thickness separates the stator and rotor during measurement, thus forming an aerostatic bearing. Precise Machining, Thermal treatments to ensure crash-proof design, Special processes like lapping for profile correction, Geometrical and profile measurements during different stages in the sequence for controlling the bearing parameters using Coordinate Measurement Machine (CMM) are the challenges involved in the machining and realization of the ASB components and the same is discussed in this paper.

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Vahdati, Mehrdad, E. Azimi e Ali Shokuhfar. "Air Characteristics in Air Turbine Spindle of Ultra Precision Machines". Defect and Diffusion Forum 297-301 (aprile 2010): 396–401. http://dx.doi.org/10.4028/www.scientific.net/ddf.297-301.396.

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Air Spindles have been used in ultra precision machines for several years due to their advantages such as high speed rotation, low friction, and low vibration, [1]. Air spindles are widely used in these machines for producing precise work pieces. Although, spindles function on a very complicated theoretical basis, [2, 3], their structure is very simple and consists of mainly a rotor and a stator. The rotor/stator could be made of different shapes. A cylindrical shape is the one commonly in use. The spindle designed in this work has a spherical configuration. It has been designed so that it could be moved without application of electric motor and only by a wind turbine system, [4]. The spindle studied in this research uses compressed air for rotor suspension, and has an air turbine for rotating its shaft. A thin air film acts as bearing layer between rotor and stator. In design procedure, operation parameters such as air inlet pressure for turbine, air inlet pressure for bearing, diameter of turbine nuzzles, diameter of bearing nuzzles, clearance between rotor and stator and etc. have been considered, [5]. A prototype spindle has been manufactured using design criteria. The influence of above mentioned parameters have been recognized through experiments.

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Lu, Jie, Zhihua Chen, Hongbo Liu e Zimei Guo. "Behavior of eccentrically loaded welded hollow spherical joints after elevated-temperature exposure". Advances in Structural Engineering 22, n. 6 (29 novembre 2018): 1352–67. http://dx.doi.org/10.1177/1369433218815432.

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Welded hollow spherical joint is an extremely widely used connection pattern in space lattice structures. Understanding the behavior of the welded hollow spherical joint after elevated-temperature exposure is critical for the fire damage assessment of the entire space lattice structures. In this study, both experimental and numerical studies were conducted to reveal the mechanical behavior of eccentrically loaded welded hollow spherical joints subjected to eccentric loads after cooling from three elevated temperatures up to 1000°C, wherein two different methods were considered, namely, air and water cooling. Associate mechanical performance, such as load versus longitudinal displacement and load versus steel tube rotation responses, initial stiffness, load-bearing capacities, and strain development, were obtained and further analyzed. The results showed that the behavior of welded hollow spherical joints began to change when the exposure temperatures exceeded 600°C, with obvious reductions in both stiffness and strength. In addition, the influences of different cooling methods were significant. The joints cooled by water generally presented higher load-bearing capacities than those cooled by air. Furthermore, three-dimensional finite element analysis was conducted via ABAQUS software. After validating the finite element model against experimental results, parametric studies were performed and a practical formula was proposed to calculate the load-bearing capacity of welded hollow spherical joints subjected to eccentric load after elevated-temperature exposure.

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Costa, Rômulo Fernandes, Osamu Saotome e Elvira Rafikova. "Simulation and Validation of Satellite Attitude Control Algorithms in a Spherical Air Bearing". Journal of Control, Automation and Electrical Systems 30, n. 5 (23 luglio 2019): 716–27. http://dx.doi.org/10.1007/s40313-019-00497-4.

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7

Zorge, R. A. "Measurements on a miniature spherical air bearing by using its electrical gap capacitance". Measurement 11, n. 2 (aprile 1993): 159–72. http://dx.doi.org/10.1016/0263-2241(93)90015-a.

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Lee, Kok-Meng, Dan E. Ezenekwe e Tian He. "Design and control of a spherical air-bearing system for multi-d.o.f. ball-joint-like actuators". Mechatronics 13, n. 2 (marzo 2003): 175–94. http://dx.doi.org/10.1016/s0957-4158(01)00037-x.

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Dynich, R. A., A. D. Zamkovets, A. N. Ponyavina e E. М. Shpilevsky. "Dependence of a surface plasmon resonance absorption band on the concentration of gold nanoparticles in carbon-bearing matrixes". Proceedings of the National Academy of Sciences of Belarus. Physics and Mathematics Series 55, n. 2 (28 giugno 2019): 232–41. http://dx.doi.org/10.29235/1561-2430-2019-55-2-232-241.

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For fullerene matrixes doped by gold nanoparticles we have established experimentally a miss of a red concentration-induced shift of surface plasmon resonance absorption band maximum. Theoretical modeling has been made for spectral characteristics of carbon–bearing nanostructures. Numerical calculations of extinction factors for a spherical metallic particle in an absorbing surrounding medium were based on the Mie theory. Transmission spectra coefficients of densely packed plasmonic nanoparticles monolayers were calculated with the use of the single coherent scattering approximation modified for absorbing matrices. Thin-film Au-air and Au–C60 nanostructures have been fabricated on glass and quartz substrates by thermal evaporation and condensation in vacuum at an air pressure of 2 · 10–3 Pа. The surface mass density of Au into Au–C60 nanostructures was varied in the range (3.86–7.98) · 10–6 g/cm2. The comparison of theoretical and experimental data allowed making a conclusion that the absorbency in carbon-bearing matrix leads to the attenuation of lateral electrodynamics coupling and blocks collective plasmon resonance in densely packed gold nanostructures.

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Gopinath, K., K. Raghavendra, M. K. Behera, E. V. Subba Rao, M. Umakanth e S. Gopinath. "Product Design Aspects for Design of Accurate Mass Properties Measurement System for Aerospace Vehicles". Applied Mechanics and Materials 110-116 (ottobre 2011): 4712–18. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.4712.

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Mass properties of aerospace vehicle viz Weight, Center of Gravity (Xcg, Ycg, Zcg) & Mass Moment of Inertia (Ixx, Iyy & Izz) are critical inertial parameters which are vital to meet the intended mission objectives. Accurate mass properties measurement is needed for fast maneuvering aerospace vehicles to meet the Control and Guidance requirements within the tolerable limits generated by the System Designer. Mass properties estimation is vital during the configuration design phase of an aerospace vehicle. Assumptions and Constraints during the configuration design, limits the accuracy of estimations making the mass properties measurement mandatory. The mass properties of the aerospace vehicle can be measured by numerous methods, but for achieving high accuracies within the tolerable limits, the measurement system should have advanced technologies and measurement methodologies. Based on the experience, mass properties measurement systems were designed using Load Cells and Cross-Flexural Pivots in two different systems (Weight and CG in System-1, MOI in System-2), which have limited accuracy and also involves tedious external measurements. Adopting Air-Bearing (T / H / Spherical shape) supported with accurate sensors using Inverted Torsion Pendulum method, Multiple Point Weighing method and a proper measurement methodology, enhances the accuracy of the measurement system. Usage of spherical bearing yields a better accurate system but has the difficulty in realization of the system indigenously, whereas use of T or H-shape bearing is a feasible solution for achieving the desired accurate mass properties specifications. This paper gives an insight into to the product design aspects to be considered for realization of accurate mass properties measurement system.

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Waterhouse, R. B. "The Fretting Wear of Nitrogen-Bearing Austenitic Stainless Steel at Temperatures to 600°". Journal of Tribology 108, n. 3 (1 luglio 1986): 359–62. http://dx.doi.org/10.1115/1.3261201.

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The fretting behavior of the nitrogen-bearing austenitic stainless steel, Nitronic 60, has been studied at 20, 400, 500, and 600°C in air. A spherical ended rider was vibrated against a flat specimen, both machined from the steel. Normal load was 3N, frequency 50Hz and peak-to-peak amplitude 40 μm. Coefficient of friction after 106 cycles showed a decrease as the temperature was increased, falling from 0.62 at 20°C to 0.10 at 600°C. Wear volume also dropped dramatically at 400° and above, with no measurable wear at 600°C. A smooth protective oxide was formed at 400, 500, and 600°C, typical of the glaze oxide previously found on nickel-based alloys. The oxide layer was approximately 10 μm thick and had the spinel structure. The electron diffraction pattern most closely resembled that of the spinel NiO, Cr2O3 but chemical tests showed that it contained iron. It is thought to be a mixed spinel containing all three metal ions.

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Qiu, Ming, Zhi Lun Gao, Guo Feng Wang e Long Chen. "Tribological Properties of Spherical Plain Bearings with Self-Lubricating PTFE Woven Liners". Advanced Materials Research 338 (settembre 2011): 607–10. http://dx.doi.org/10.4028/www.scientific.net/amr.338.607.

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The friction and wear behaviors of three kinds of spherical plain bearings with PTFE fabric composite liners were investigated by a high oscillating frequency and heavy load tribo-tester. Dry sliding tests were carried out at different oscillating frequencies. With the help of SEM and EDS, the differences of worn surfaces of the three spherical bearings were investigated. The results indicate that the fiber woven with PTFE effects the friction and wear characteristics of bearing, the tribological properties of bearing with Kevlar/PTFE fiber woven liner is the best in the three kinds of bearing. The abrasive wear are appeared on the surface of wore liners of bearingⅠ,while bearingⅡappeared normal wear, bearing III showed serious adhesive wear and abrasive wear.

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Wang, Fu Sheng, e Gang Bao. "Research on a New Type of Center of Mass Measuring Instruments". Applied Mechanics and Materials 29-32 (agosto 2010): 1722–27. http://dx.doi.org/10.4028/www.scientific.net/amm.29-32.1722.

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The accurate measurement and control of center of mass (CM) in mass properties for satellite attitude control are the most important. In order to accurately measure CM, this paper describes a new type of CM measuring instruments which are particularly recommended for determining mass properties of rockets, satellite and ballistic objects. A spherical air-bearing supports a precision rotary table and acts as a frictionless pivot axis for measuring unbalance moments due to the displacement of the test part CM relative to the central axis of the bearing. This paper emphasizes the research on reasons and laws of the load table CM offset caused by the elastic deformation, and according to curve theory of thin plates derives the formulary for the element center of mass displacement of the finite element and for the platform structure center of mass elastic displacement, and calculates the CM elasticity offset and the unbalance moment caused by the deformation of loaded table. The research results provide bases for the structure design of rotary tables.

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Gude, Venkatesh. "Synthesis of hydrophobic photoluminescent carbon nanodots by using L-tyrosine and citric acid through a thermal oxidation route". Beilstein Journal of Nanotechnology 5 (11 settembre 2014): 1513–22. http://dx.doi.org/10.3762/bjnano.5.164.

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Hydrophobic photoluminescent carbon nanodots (CNDs) were fabricated by using citric acid and L-tyrosine precursor molecules through a simple, facile thermal oxidation process in air. These CNDs (less than 4 nm in size) exhibited a characteristic excitation wavelength dependent emission and upconversion emission properties and are insoluble in water, but soluble in organic solvents. FTIR and 1H NMR analyses showed a selective participation of L-tyrosine molecule during the carbonization process at 220 °C without a disturbance of its benzylic protons and aromatic phenyl ring bearing hydroxy group. TEM and XRD studies revealed a quasi-spherical morphology and poor-crystalline nature of CNDs. Because the presence of the hydroxy group of L-tyrosine is dominating at the surface, these CNDs are also soluble in water under basic conditions. The effects of base and silver nanoparticles on the luminescence properties of CNDs were studied and a quenching of fluorescence was observed. These tyrosine-passivated CNDs are applicable for both biologically and commercially.

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Qiu, Ming, Zhi Lun Gao, Guo Feng Wang e Long Chen. "Friction and Wear Characteristics of Spherical Plain Bearings with PTFE Woven Liners". Advanced Materials Research 199-200 (febbraio 2011): 763–66. http://dx.doi.org/10.4028/www.scientific.net/amr.199-200.763.

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The friction and wear behaviors of three kinds of spherical plain bearings with PTFE woven liners were investigated by a high oscillating frequency and heavy load tribo-tester. Dry sliding tests were carried out at an oscillating frequency of 1.2Hz and four different loads. With the help of SEM and EDS, the differences of worn surfaces of the three kinds were investigated. The results indicate that the wear depth and friction temperature for the three kinds of bearings show increasing trend with the increasing of load, while the friction coefficient is the opposite. The comprehensive performance of bearing II is the best in the whole course of experiment, while the bearing III is the worst. The adhesive and abrasive wear mechanisms are appeared on the surface of liners. The quality of boning influences the tribological property of the spherical plain bearing.

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Wang, Jing, Li Ying Yang, Shou Ren Wang, Guang Ji Xue e Chang Xiu Zhou. "Stress Distribution Behavior of Spherical Plain Bearing Fabricated by TiAl-Based Composite Materials Based on the Finite Element Analysis". Advanced Materials Research 1061-1062 (dicembre 2014): 649–52. http://dx.doi.org/10.4028/www.scientific.net/amr.1061-1062.649.

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Spherical plain bearing is a sliding bearing have a spherical contact surface,it can bear larger load and automatically adjusted to the self-alignin. TiAl-based composite material is a material that be used to lightweight spherical plain bearing. The Simulation used the finite element software Ansys for the bearing’s static analysis.The material of outer ring using normal bearing steel, one group used the TiAl-based composite materials as the material of the inner ring, Another group the inner ring material is bearing steel 9Cr18. The law of the stress and strain produced by the two groups is consistent,the deformation of the composite materials is bigger under the same load, its elasticity modulus and density is smaller compared to the ordinary bearing steel,the composite material has the advantages of high specific strength especially in the occasions have strict requirements of the bearing weight.

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Cao, Lei, Xue Jin Shen e Ru Yan Li. "Three-Dimensional Thermal Analysis of Spherical Plain Bearings with Self-Lubricating Fabric Liner". Advanced Materials Research 97-101 (marzo 2010): 3366–70. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.3366.

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Finite element analysis and corresponding experimental comparisons of temperature were performed to investigate the thermal behaviour of spherical plain bearings with self-lubricating fabric liner. Based on the theory of heat transfer, tribology and composite material mechanics, a sequentially coupled, 3D, thermo-mechanical finite element analysis model of the bearing system was built up, in which the steady-state temperature distribution from the thermal analysis was applied as a body load to the structural model. As a result, the maximum steady-state temperature of 78.1°C, von Mises stress of 299MPa, displacement of 0.0806mm along Z axis of the bearing are presented, together with the maximum contact pressure of 324MPa which are significant in the structural design and optimization of these bearings. The effect of temperature rise on the contact pressure distribution is discussed. The agreement of the temperature computation results with the experimental data indicates that this method could be used to analyze virtually any such bearing.

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YOSHIMOTO, Shigeka, Keita FUNATO e Kazuyuki YAGI. "Foil Air Thrust Bearings with Hemi-Spherical Bumps". Proceedings of the JSME annual meeting 2004.4 (2004): 93–94. http://dx.doi.org/10.1299/jsmemecjo.2004.4.0_93.

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Reinacher, Andreas, Friederike Graf, Benjamin Greiner, Holger Jakob, Yannick Lammen, Sarah Peter, Manuel Wiedemann, Oliver Zeile e Hans J. Kaercher. "The SOFIA Telescope in Full Operation". Journal of Astronomical Instrumentation 07, n. 04 (dicembre 2018): 1840007. http://dx.doi.org/10.1142/s225117171840007x.

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The SOFIA telescope is a 2.5[Formula: see text]m class Cassegrain telescope with Nasmyth focus. It is the largest telescope ever integrated into an aircraft. The telescope is exposed to the stratospheric environment during the observations and the fact that the telescope’s foundation, which is a Boeing 747 SP, is vibrating and moving in all degrees of freedom (DoF) requires a highly specialized and sophisticated design. Based on the telescope of its predecessor, the Kuiper Airborne Observatory (KAO), the SOFIA telescope design had to evolve to accommodate a telescope 2.5 times the size of KAO. In several hundred successful observation flights, the telescope proved that it performs not only as specified, but is also extremely reliable. Nevertheless, the telescope’s software and hardware are continuously upgraded to optimize its performance without interfering with the observation schedules to reach even more ambitious image size and pointing jitter goals to enable additional science cases. In addition, manufacturing of the line-replaceable units is in process to ensure that the SOFIA telescope can perform without any major interruptions for the envisioned 20 year lifetime. Some of the main features of the SOFIA telescope are its suspension assembly (SUA), which decouples the telescope from SOFIA’s fuselage with air springs and a spherical oil bearing, the extremely stiff Nasmyth tube (NT), which connects cavity and cabin mounted components of the dumbbell design, and the Secondary Mirror Assembly (SMA), which is used for chopping and fast pointing corrections. This paper aims to give an overview of these and all other major telescope subsystems in operation today. In addition, some of the upgrades, either implemented recently or slated for implementation shortly, are introduced.

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Garibaldi, A., A. Minuto, D. Bertetti e M. L. Gullino. "First Report of Peronospora arborescens as the Causal Agent of Downy Mildew on Papaver nudicaule in Italy". Plant Disease 87, n. 10 (ottobre 2003): 1265. http://dx.doi.org/10.1094/pdis.2003.87.10.1265b.

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Iceland poppy (Papaver nudicaule L.) is increasingly grown on the Italian Riviera for export as a cut flower. During the spring of 2003, leaves with irregular, brown, angular spots were collected from a commercial crop grown outdoors near Ventimiglia (northern Italy) with temperatures ranging from 3 to 14°C. Leaves of infected plants appeared curled and blistered; the infected portions of the leaves turned chlorotic. On both surfaces of infected leaves, a characteristic gray, furry growth was evident, particularly at the center of the necrotic areas. Infected leaves eventually died without dropping. Basal leaves with poor air circulation were the most severely affected by the disease. Microscopic observations revealed conidiophores branching dichotomically at least five times. Conidiophores ended with sterigmata bearing single conidia. Conidia measured 19 to 24 × 16 to 18 μm and were elliptical to near spherical and hyaline. Oospores were not present. The pathogen was identified as Peronospora arborescens based on the morphological characteristics (2). Pathogenicity was confirmed by inoculating 60-day-old healthy P. nudicaule plants with a conidial suspension (1 × 105 conidia per ml). Five plants were used as replicates. Inoculated and noninoculated plants were maintained in a growth chamber at 15°C and 90 to 95% relative humidity. After 7 to 10 days, typical symptoms of downy mildew developed oninoculated plants. Peronospora arborescens was observed on infected leaves. Noninoculated plants did not show symptoms. To our knowledge, this is the first report of Peronospora arborescens on P. nudicaule in Italy. Peronospora arborescens was previously reported on P. nudicaule and on many other species of Papaver (P. somniferum, P. dubium, P. caucasicum, P. rhoeas, P. setigerum, and P. argemone) in everal countries (1,2). References: (1) P. J. Cotteril and I. G. Pascoe. Australas. Plant Pathol. 27:263, 1998. (2) S. M. Francis. No. 686 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, U.K., 1981.

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Gu, Jing, Xiao Mei Huang e Jian Hua Sui. "Research on Performance of MPIA/PTFE Union Fabric Used as Self-Lubricating Bearings Liner". Advanced Materials Research 796 (settembre 2013): 225–28. http://dx.doi.org/10.4028/www.scientific.net/amr.796.225.

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Self-lubricating bearings liner is a fabric that can extend the period of use of spherical plain bearing. In this paper, the structural parameter of self-lubricating bearings liner was discussed. Taking MPIA as warp, respectively the MPIA/PTFE twisting yarn and PET/PTFE twisting yarn as weft, we obtained 12 fabrics by changing the weft surface effect of fabric structure, linear density and twist of weft. Then, the wear resistance and frictional property of the fabrics were tested, and the relationship between the factors was analyzed. The data shows that the wear resistance and frictional properties of the fabric with change of different factors. In comprehensive, more suitable self-lubricating bearings liner can be made by selecting MPIA and MPIA/PTFE twisting yarn intertwined, increasing weft surface effect, with moderate weft twist factor, and increasing weft linear density.

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Peng, Tian Bo, Zhen Nan Wang, Xun Tao Yu e Cheng Yu Yang. "Application of Expansion Double Spherical Seismic Isolation Bearing in Seismic Design of Continuous Girder Bridges". Advanced Materials Research 243-249 (maggio 2011): 1928–34. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.1928.

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The double spherical seismic isolation (DSSI for short) bearing has been adopted in seismic design of several important engineering projects since developed recently. It was used generally as fixed bearings in a continuous girder bridge in these projects, and only a few fixed piers, usually just one fixed pier would transmit the horizontal earthquake action to the foundation, which is uneconomical and results in the much larger seismic risk in the longitudinal direction of a continuous girder bridge than that in the transverse direction. In order to share the earthquake effect with all the piers and avoid relative vertical displacement among all the bearings under the normal traffic conditions, a new seismic design method of continuous girder bridges is introduced. The configuration and working mechanism of two kinds of DSSI bearings used to make the new seismic design possible are introduced. It’s shown that the method is preferable for the seismic design of continuous girder bridges by a numerical seismic analysis with a four-span continuous girder bridge.

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Chen, Wei Jing, Zheng Lin Liu, Sheng Dong Zhang, Liang Zhao e Peng Liu. "Study on Structure and Performance Optimization for Spherical Stern Bearing Based on ANSYS". Advanced Materials Research 744 (agosto 2013): 44–48. http://dx.doi.org/10.4028/www.scientific.net/amr.744.44.

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Spherical stern bearing is kind of new bearing, which combines ordinary water lubricated stern bearing with sphere bearing. It has function to adjust contact situation of stern bearing and stern shaft automatically, decreases pressure peak, leads to pressure distribution on the bearing being more uniform, helps to overcome the problem of local overload to avoid edge effect and improves damping performance. On the base of the ANSYS software, the contact deformation and pressure calculation of spherical stern bearing are carried out to compare with ordinary stern bearing and analyse the effectiveness of reducing pressure on bearing, optimization problems of the sphere position and sphere diameter are discussed, which shows that the contact pressure achieves a minimum when the sphere is located at intermediate position of bearing bush and the maximum contact pressure decreases with the increase of sphere diameter, and they have linear relation.

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CHOI, Woo Chun, Keun Hyung PARK, Jung Hwan CHOI, Kwonhee KIM e Byung Chun KOH. "Axial Impulse Performance of Self-Acting Semi-Spherical Air Bearings." JSME International Journal Series C 44, n. 1 (2001): 25–29. http://dx.doi.org/10.1299/jsmec.44.25.

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Wang, Fu-sheng, e Gang Bao. "Static characteristics of new type externally pressurized spherical air bearings". Journal of Central South University of Technology 18, n. 4 (10 luglio 2011): 1133–38. http://dx.doi.org/10.1007/s11771-011-0814-3.

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Yan, Bin, e Peng Liu. "Study on Seismic Performance of Double Spherical Bearing". Advanced Materials Research 255-260 (maggio 2011): 2488–91. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.2488.

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Continuous Beam Bridge was widely used, while seismic problem of it was prominent in meizoseismal area. According to mechanism of DSB, seismic performance of DSB was studied and the parameters of DSB were analyzed later, based on non-navigable bridge of Hong Kong-Zhuhai-Macau Bridge in deep water. It was found that DSB was an effective seismic-isolation device which could significantly reduce the seismic force although seismic displacement of bridge was increased. Yielding force and post-yielding stiffness were two main parameters of DSB.

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Peng, Tian Bo, Xun Tao Yu e Zhen Nan Wang. "Development of a Kind of Multi-Defense Seismic Spherical Bearing". Advanced Materials Research 255-260 (maggio 2011): 972–76. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.972.

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For continuous girder bridges, each bearing has different function requirements under normal traffic conditions and under earthquakes of different intensity levels. To meet the requirements of the three-level seismic design for continuous girder bridges presented in this paper, a new kind of multi-defense seismic spherical bearing is developed and its configuration and working mechanism are introduced in this paper. Then the results of mechanical properties test of the bearing are presented and it’s shown that the design requirements are all satisfied and the seismic performance of the bearing is effective and reliable.

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Wang, Jia Tao, Xiang Hong Song e Li Wen Zhang. "Research on Time Effect of Bearing Capacity of Jacked Pile in Soft Soil". Advanced Materials Research 403-408 (novembre 2011): 1896–99. http://dx.doi.org/10.4028/www.scientific.net/amr.403-408.1896.

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Through the study on the characteristics of bearing capacity of jacked pile in soft soil, it is found that the increment of ultimate bearing capacity of the single pile is mainly determined by pile side resistance. The end resistance has little influence on the time effect of bearing capacity of pile. The relationship between ultimate bearing capacity and time can be expressed with logarithmic curve. According to penetration mechanism of jacked pile, the expansion of a series of spherical cavities in semi-infinite space is used to simulate the process of pile installation. Soil is assumed as Mohr-Coulomb material. Based on the theory of spherical cavity expansion, estimating formulas were proposed to calculate the ultimate side frictional resistance. Then the ultimate bearing capacity of single pile in different time can be obtained. Analyses show that the calculation results are close to the measured data and the error between computed and measured value is little. So it is acceptable for the formula to forecast bearing capacity of jacked piles.

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Wang, Fu-sheng, e Gang Bao. "Characteristics of supersonic flow in new type externally pressurized spherical air bearings". Journal of Central South University 19, n. 1 (gennaio 2012): 128–34. http://dx.doi.org/10.1007/s11771-012-0981-x.

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Huang, Yu Feng, Xue Jin Shen, Shuai Lv e Lei Cao. "The Discussion about Thermal Stress Analysis of Spherical Plain Bearings". Advanced Materials Research 479-481 (febbraio 2012): 305–8. http://dx.doi.org/10.4028/www.scientific.net/amr.479-481.305.

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Spherical plain bearing was applied widely in industry. In the paper, with the finite element code Abaqus, a sequentially coupled, 3D, and thermal-mechanical finite element analysis model of the bearing system was built up based on the theories of heat transfer, tribology and composite material mechanics. The paper focused on effects of the mean sliding velocity and the load. In the end, the paper mentioned a simulation method of computing wear.

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31

Zhao, Xiu Ting. "FEM Simulation on Cold Rolling of Outer Spherical Bearing Ring". Advanced Materials Research 139-141 (ottobre 2010): 1088–92. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.1088.

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Abstract (sommario):

Ring rolling theory based on completion of the mold, rough and technical parameters of the design, application Abaqus software to build three-dimensional model of rolling, and the use of Abaqus / Explicit algorithm of external spherical bearing outer ring of cold ring rolling simulation and analysis come to different mold shape, size, structure and guide roller feed specifications on the forming process, reveals a spherical bearing outer ring of the mechanism of cold ring rolling, gets die structure is different, different size core roller, guide rollers with different combinations of cold rolling play a crucial role in forming quality. At the same time by rolling the solution results demonstrate the power of cold ring rolling of the nonlinear characteristics. Revealed the ring rolling process is a complex interaction of multi-parameter deformation coupling.

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32

REN, Di. "Effect of Manufacturing Errors on Static Characteristics of Externally Pressurized Spherical Air Bearings". Chinese Journal of Mechanical Engineering 22, n. 06 (2009): 896. http://dx.doi.org/10.3901/cjme.2009.06.896.

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33

Feng, Kai, Zheng Huang e Zhi-Yang Guo. "Design of Spherical Spiral Groove Bearings for a High-Speed Air-Lubricated Gyroscope". Tribology Transactions 58, n. 6 (settembre 2015): 1084–95. http://dx.doi.org/10.1080/10402004.2015.1045650.

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34

CHOI, Woo Chun, Keun Hyung PARK, Jung Hwan CHOI, Kwonhee KIM e Byung Chun KOH. "Study on the Performance of Spiral-Grooved Semi-Spherical Air Bearings Using Taguchi Method." JSME International Journal Series C 43, n. 1 (2000): 157–63. http://dx.doi.org/10.1299/jsmec.43.157.

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35

Yu, Jiang Tao, Ke Quan Yu e Bo Tang. "Experimental and Finite Element Analysis on the Ultimate Bearing Capacity of Hollow Spherical Joints with Ribbed Stiffener". Advanced Materials Research 163-167 (dicembre 2010): 670–75. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.670.

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Abstract (sommario):

Four groups (12 in total) of welded hollow spherical joints with ribbed stiffener were tested under uniaxial loads in this paper. With the adoption of elasto-plastic model and consideration of geometric and material nonlinearity, the whole loading process of the specimens was simulated by ABAQUS. Through combining the test data and computing results, two recommendations used to quantitatively determine the ultimate failure load of spherical joint in test are proposed. The relationships between bearing capacity and various influence factors, which include the thickness and diameter of hollow sphere, diameter of steel tube are analyzed and illustrated at the end of this paper.

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36

Li, Feng, e Xiang Bing Min. "Ultimate Bearing Capacity Analysis of Schwedler Suspendome". Advanced Materials Research 255-260 (maggio 2011): 4197–201. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.4197.

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Abstract (sommario):

Prestress suspendome structure is a new two-double space structure system, which is composed of single-layer spherical reticulated shells and cable-strut tensile structure, and taking full advantages of two systems. Compared to single-layer shells, stiffness and stability are improved effectively. Compared to cable dome, designing, constructing and joint treatments are simplified much more easily. In this paper, taking geometrical nonlinearity and material nonlinearity into account, the stable ultimate bearing capacity of Schwedler suspendome was analyzed theoretically by employing a nonlinear finite element method. Structural parameters of the suspendome, such as prestresses of cables, heights of struts, rise-span ratio and cable layout, which influence the structural stable ultimate load-carrying capacity, having been analyzed by employing the two-double computational mode of Schwedler suspendome of 40m span. Some valuable and reasonable conclusions are drawn for practical engineering design by theoretically analysis.

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37

TANAKA, Keita, Yuichi TSUDA, Takanao SAIKI, Yoji SHIRASAWA e Ryo JIFUKU. "The Development of Spherical Gas Bearings for the 3DRW Operated by a Small Air Supplier". TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN 10, ists28 (2012): Pd_93—Pd_99. http://dx.doi.org/10.2322/tastj.10.pd_93.

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38

Su, Na, Ivan Chen, Hou Bin Li, Xing Hai Liu e Xin Xin Zhu. "Preparation and Performance of Cationic Spherical Polyelectrolyte Brushes as Retention and Drainage Aid in Papermaking". Advanced Materials Research 174 (dicembre 2010): 333–36. http://dx.doi.org/10.4028/www.scientific.net/amr.174.333.

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Abstract (sommario):

Novel cationic spherical polyelectrolyte brushes (CSPBs) were prepared by photoemulsion polymerization. Dimethyl diallyl ammonium chloride was grafted onto the surface of polystyrene particles bearing a thin layer of photoinitiator that was prepared by Schotten-Baumann reaction of Darocur 1173 and Methacryloyl chloride. Transmission electron microscopy (TEM) was used to analyze the size and shape of CSPBs, the average diameter of these particles with uniform spherical structure was ca.170nm. A link to the use of this system as a model for retention and drainage aid in the papermaking process was described. Dynamic drainage experiment indicated that the shortest drainage time was 23.2s when the percentage of the aid was 0.04%(wt). The retention effect of the aid was tested that the highest of the first-pass retention was 70.89% when the percentage of aid was 0.035%(wt).

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39

Ma, Chun Rong, Yu Lin Yang, Ji Gang Chen, Lin Lin Cui e Xiao Tian Zhang. "Unconstrained Surface Directional Rolling Process Optimization of Self-Lubricating Spherical Plain Bearing’s Integral Outer Ring". Advanced Materials Research 968 (giugno 2014): 267–73. http://dx.doi.org/10.4028/www.scientific.net/amr.968.267.

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Abstract (sommario):

Self-lubricating bearings are the basic components of the aviation industry, and the precision forming process of bearings is one of the kernel technologies, which is urgent to be self-developed. A method called unconstrained surface directional rolling process was put forward, and then the flow chart of process optimization was designed. Based on the numerical analysis model of rolling process, Latin hypercube sampling method was used for the design-space analysis. By using BPF+NSGA-II and Kriging+PSO algorithms, the rolling process was simulated and optimized, and then the results were verified by experiments. Study shows that by the use of the new proposed process and the optimization methods, the products can get a higher quality; results of optimization and experiments are valid and consistent, comparing with BPF+NSGA-II algorithm, results of Kriging+PSO algorithm are slightly better.

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40

Zhang, Yu Lan, Zhi Hua Chen, Yong Jian Liu, Xie Jin Wei e Yi Du Bu. "Study on Mechanical Properties of Ribbed Cast Steel Spherical Joint in Complex Stress State". Advanced Materials Research 284-286 (luglio 2011): 1120–25. http://dx.doi.org/10.4028/www.scientific.net/amr.284-286.1120.

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Abstract (sommario):

Cast steel joints have been widely utilized in large-span spatial structures. Based on Ordos airport terminals engineering, the structure and design method of ribbed steel ball nodes is put forward in this essay, in which nonlinear finite element method is applied, bearing capacity and deformation capacity of ribbed steel ball nodes in the complex stress state is made a penetrating analysis to determine mechanical performance of the ribbed steel ball. Among other things, the manufacturing process and technical standards of cast steel ball nodes are elaborated.

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41

Zhang, Ji Wang, Kazuaki Shiozawa, Lian Tao Lu, W. Li e Wei Hua Zhang. "Fatigue Fracture Behavior of Bearing Steel GCr15 in Very High Cycle Regime". Advanced Materials Research 44-46 (giugno 2008): 119–26. http://dx.doi.org/10.4028/www.scientific.net/amr.44-46.119.

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Abstract (sommario):

In order to investigate the fatigue behaviors in very high cycle fatigue regime of bearing steel GCr15 (Chinese standard), cantilever-type rotary bending fatigue test was carried out, by using an hourglass-shaped specimen. As a result, the S-N data were classified into surface grinding flaw or inclusion induced fracture mode, subsurface inclusion without ‘granular-bright-facet’ (GBF) area induced fracture mode and subsurface inclusion with GBF area induced fracture mode. Formation of a GBF area was clearly observed in the vicinity of subsurface inclusion on the fracture surface ruptured at high- cycle fatigue regime. The cause of the S-N curves of GCr15 obtained by this experiment continuously decreased, which is different from the common ‘duplex S-N’ curve. Experiments on fracture surface was carried out based on the ‘dispersive decohesion of spherical carbide’ model aimed to clarify the mechanism of the formation of GBF area.

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42

Voronin, Nikolay A. "Abnormal Structural Strength of Topocomposites". Advanced Materials Research 560-561 (agosto 2012): 338–43. http://dx.doi.org/10.4028/www.scientific.net/amr.560-561.338.

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Abstract (sommario):

The mechanics of contact interaction of rigid spherical indenter with two-layer elastic - plastic half-space, simulating a surface of a solid body with a thin surface layer is considered. Analytical dependences of critical indentation and bearing capacity on mechanical characteristics of materials of a base and a coating, and as well as that for thickness of top layer (coating) in all region of possible thickness are received and analyzed. Existence of regions of the abnormal structural strength allowing the surface layered material to identify unequivocally as a topocomposite is shown. Theoretical dependences were verified by a final elements method.

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43

Liu, Zhao Lei, e Xue Jin Shen. "Study on the Elastic Properties of the Woven Fabric Liner of Spherical Plain Bearing with Self-Lubricating". Advanced Materials Research 139-141 (ottobre 2010): 190–93. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.190.

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Abstract (sommario):

The structure of the woven fabric liner of spherical plain bearing with self-lubricating is introduced, according to the microstructure and the actual weave pattern of the liners, the fibre yarns undulation and the distance between two fibre yarns are taken into account. A general elastic properties analysis model adjusting to the stain woven fabric liner is built. The elastic properties of the fabric liner are obtained using the method of micromechanical through getting the material and geometric parameters of the fiber yarns in the basis of stiffness average. The parameter expression of the compliance matrix and nine elastic constants are obtained and the theory model of fabric liner is validated by the experiment. The calculation results are in good agreement with the experimental data.

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44

Chang, Yu Zhen, e Ling Ling Wang. "The Influence of Different Restrained Boundary Conditions on the Stability of Steel-Concrete Composite Ribbed Shell". Advanced Materials Research 243-249 (maggio 2011): 7005–8. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.7005.

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Abstract (sommario):

The steel-concrete composite ribbed shell is a new type of spatial structure. Different restrained boundary conditions have a considerably influence on the ultimate bearing capacity and stability. Based on the nonlinear finite element method, a numerical model is made by finite element analysis software ANSYS, in which material and geometrical nonlinear are considered. A spherical composite ribbed shell with 40m span, three different section dimensions and two different vector heights is used as an example, in which 4 different restrained boundary conditions are considered, including all fixed, all hinged, node fixed and node hinged. The results show that when the section dimension and span height are the same, the ultimate bearing capacity will be greater as the boundary becoming rigid, and when the section dimension is larger, the ratio of ultimate bearing capacity under different restrained boundary conditions is increasing, while as the span height is greater, the ratio is decreasing. To the instable shape, the influence of different restrained boundary is minor, all the instable modes are extreme point instability, but the trend of load-displacement curves are almost similar, and when the cross-section dimension of composite rib increases, the composite ribbed shell under different boundary constraints has shown higher post-buckling strength.

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45

Wu, Wei Yu, e Guo Hua Liu. "A Modified Drucker-Prager Criterion for Transversely Isotropic Geomaterials and its Numerical Implementation". Advanced Materials Research 850-851 (dicembre 2013): 115–19. http://dx.doi.org/10.4028/www.scientific.net/amr.850-851.115.

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Abstract (sommario):

A failure criteria basing on Drucker-Prager yield criterion for geomaterials is modified in terms of the inherent anisotropy of the friction angle and the dilation angle. To implement the model in a numerical way, the corresponding consistent return mapping algorithm is formulated and by dividing the scalar product of the stress rate and the strain rate into the deviatoric and spherical parts, the consistent elastoplastic tangent modulus matrix is obtained. Then, the codes are introduced into finite element software ABAQUS via the UMAT. An example has been presented illustrating influence of the anisotropic degree on the bearing capacity and the pattern of strain localization.

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46

Jiang, Ren Hao, Wei Li, Yan Ping Shi e Jiang He. "Study on Interior Fracture Property of High Strength Steel in Very High Cycle Regime". Advanced Materials Research 482-484 (febbraio 2012): 1169–75. http://dx.doi.org/10.4028/www.scientific.net/amr.482-484.1169.

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Abstract (sommario):

Based on the fracture mechanics theory and fracture surface topography analysis (FRASTA) method, the interior fracture property of a bearing steel in very high cycle regime was studied by means of rotary bending fatigue test. As a result, this bearing steel represents the duplex S-N curves characteristic, where the interior inclusion-induced fracture is the predominant fracture mode in very high cycle regime. The rough granular bright facet (GBF) area corresponding to smaller inclusion is usually formed in the lifetime larger than 106 cycles, whose formation progress can be interpreted as the slow crack nucleation based on decohesion of spherical carbide from the matrix. The fatigue property in the fish-eye region outside of GBF can be interpreted as the stable crack propagation progress and that outside of fish-eye is instable crack propagation progress. The stress intensity factor ranges of GBF and fish-eye, ΔKGBF and ΔKfish-eye, can be regarded as the threshold values of controlling stable propagation and instable propagation of interior crack, respectively.

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47

Zhou, Yong, e Bing Liu. "Synthesis and Self-Assembly Behavior of Chiral Amphiphilic Diblock Copolymers Bearing L-Phenylalanine". Advanced Materials Research 345 (settembre 2011): 334–37. http://dx.doi.org/10.4028/www.scientific.net/amr.345.334.

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Abstract (sommario):

Novel chiral amphiphilic diblock copolymers bearing L-phenylalanine was synthesized using a “click” reaction of N3-L-phenylalanine and MPEO-b-PGPE. The structure and composition of copolymers were characterized by 1H-NMR and elemental analysis. Additionally, the self-assembly behavior of these chiral copolymers was investigated in sodium dihydrogen phosphate buffer (pH 4.5): the CMC of copolymer MPEO-b-PGTP determined by the measurement of surface tension was 2.1 mg/mL; the size and morphology of the micelles were studied using TEM; the specific optical rotation ([α]25D) of the micellar solutions was also measured; the result indicated that the copolymers can form chiral micelles in sodium dihydrogen phosphate buffer (pH =4.5).In recent years, the synthesis, structure and properties of optically active polymer have been paid attention by scientists owing to its potential applications in chiral separation, asymmetric adsorption, chiral synthesis[1]. The amphiphilic block polymers bearing amino acid possess not only the characteristics of the conventional amphiphilic block copolymer, but also good optically activity and biocompatibility. So it can be employed as nanoreactors for asymmetrical catalysis and materials for drug delivery. But there have been few reports published on the synthesis of chiral amphiphilic copolymers bearing amino acid. Sutthira Sutthasupa reported the synthesis of amino acid-based norbornene block copolymer with ester and carboxyl groups as hydrophobic and hydrophilic units[2]. O’Reilly group synthesized the amino acid-based chiral amphiphilic block copolymers using RAFT technique, and elucidated its self-assembly into spherical micelles with optically active hydrophobic core[3]. In the present work, chiral amphiphilic diblock copolymers bearing L-phenylalanine (L-Phe) pendants poly(ethylene oxide)-b-poly (glycidyl triazolyl-L-phenylalanine) (MPEO-b-PGTP) have been synthesized by the modification of poly(ethylene oxide)-b-poly (propargyl glycidyl ether) (MPEO-b-PGPE) with L-phenylalanine.

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48

Zhao, Zi Hao, e Hai Wang Li. "Analysis on Dynamic Failure of Steel Spherical Latticed Shell with Vibration Isolation Bearings under Strong Earthquake". Advanced Materials Research 838-841 (novembre 2013): 1566–70. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.1566.

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Abstract (sommario):

this paper uses SAP2000 structure analysis software, designed a span of 60 m, rise-span ratio 0.25 of the double-layer spherical reticulated shell, the presence of isolation bearing of two kinds of structure forms are studied, firstly analyzes the dynamic characteristics of the two, and then used in the program focus on plastic hinge theory considering the material nonlinear and geometry nonlinear effect. EL selected seismic waves along the structure of the three-input, two structures were carried out on the elastic-plastic time history analysis.The results show that the original structure and isolated structure failure mechanism are basically the same, belong to dynamic instability failure. Structure by reducing the overall level of structure stiffness to make structural natural vibration period increases, large extent reduce the seismic response of the upper structure; And isolation structure improves the structure damage boundary peak acceleration, delay the time the collapse of the structure.

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49

Ogar, P. M., V. A. Tarasov e D. B. Gorokhov. "The Influence of Coating Thickness on the Relative Area of Tribounits Contact". Advanced Materials Research 1061-1062 (dicembre 2014): 614–18. http://dx.doi.org/10.4028/www.scientific.net/amr.1061-1062.614.

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Abstract (sommario):

The contact of a rigid rough surface and an elastic layered half-space which consists of coating with thickness δ1 and the substrate. To determine the dependence of the relative contact area on dimensionless the force elastic geometrical parameter , the discrete roughness model presented by microasperities in the form of equal spherical segments with the height distribution corresponding to the bearing profile curve of the real surface is used. By using the stiffness model of layered half-space, the elastic characteristics for every each contacting asperity are determined. The system of transcendental equations which allow to determine the dependence of the relative contact areaη1 in case of contact through coating layer on the roughness parameters, material properties, coating thickness and applied load is given. The mutual influence of the microasperities is taken into account.

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50

Wang, Shang Bin, Xin Zhou Zhang, Kai Wu e Yu Sun. "Finite Element Analysis for Belt Conveyor's Drum". Advanced Materials Research 228-229 (aprile 2011): 764–70. http://dx.doi.org/10.4028/www.scientific.net/amr.228-229.764.

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Abstract (sommario):

A new finite element analysis method of driver drum is introduced in this paper, conveyor belt is introduced in analysis model, and the effect that bearing imposed on drum is treated as spherical constraints. The drum is analyzed under the coalition of assembly load and ultimate torque load using the paper method as well as the traditional method, and the results between two methods are compared. The analysis results show that the danger points are on the hub inner and the weld seam between spoke and hub, the comparison shows that the analysis results by the paper described method are smaller than the traditional method results by 10%. The load imposing ways described in this paper are more consistent with the actual work process, and the analysis results are more accurate and reliable.

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